JP7848083B2 - Binder for all-solid-state secondary batteries, binder composition for all-solid-state secondary batteries, slurry for all-solid-state secondary batteries, solid electrolyte sheet for all-solid-state secondary batteries and method for producing the same, and all-solid-state secondary batteries and method for producing the same. - Google Patents

Description

This invention relates to a binder for all-solid-state secondary batteries, a binder composition for all-solid-state secondary batteries, a slurry for all-solid-state secondary batteries, a solid electrolyte sheet for all-solid-state secondary batteries, and a method for producing the same, as well as an all-solid-state secondary battery and a method for producing the same.

In recent years, there has been a growing demand for energy storage devices with high voltage and high energy density to power electronic devices. Lithium-ion batteries and lithium-ion capacitors are among the promising candidates for such devices.

The electrodes used in such energy storage devices are manufactured by applying and drying a composition (slurry for energy storage device electrodes) containing an active material and a polymer that functions as a binder onto the surface of a current collector. The required properties of the polymer used as a binder include its ability to bond the active materials together and its ability to adhere to the active materials and the current collector. Furthermore, when cutting the applied and dried composition film (hereinafter also referred to as the "active material layer"), it should exhibit resistance to powder shedding, preventing fine particles of the active material from falling off the active material layer. By exhibiting good adhesion with such a binder material, the internal resistance of the battery caused by the binder material can be reduced, thereby providing the energy storage device with good charge and discharge characteristics.

Furthermore, empirically, it has been clearly established that the bonding ability between the active materials, the adhesion ability between the active materials and the current collector, and the resistance to powder shedding are roughly proportional to the performance of the materials. Therefore, in this specification, these factors may be collectively referred to as "adhesion."

Currently, research into large lithium-ion batteries is thriving for use in applications such as power sources for automobiles and home energy storage systems. While most currently available lithium-ion rechargeable batteries use a liquid electrolyte, development is progressing on all-solid-state rechargeable batteries, where all constituent materials are solid, by replacing the liquid electrolyte with a solid electrolyte.

All-solid-state rechargeable batteries utilize a solid electrolyte with high ionic conductivity, eliminating the risk of leakage or fire, thus offering superior safety and reliability. Furthermore, all-solid-state batteries are well-suited for achieving high energy density through electrode stacking. Specifically, they can be constructed with a series-connected structure of the active material layer and solid electrolyte layer, eliminating the need for metal packaging to seal the battery cells, as well as copper wires and busbars connecting the cells, significantly increasing the battery's energy density. Their compatibility with positive electrode materials capable of high potential is another advantage. Thus, all-solid-state rechargeable batteries are expected to be the ultimate battery, combining safety, high energy density, and long lifespan.

On the other hand, challenges in manufacturing all-solid-state secondary batteries have also become apparent. Specifically, when a mixture of solid electrolyte and active material is used as a pressure-molded body to increase the contact area between them, the resulting pressure-molded body becomes hard, brittle, and poorly processable. Furthermore, because the active material undergoes volume changes due to the intercalation and release of lithium ions, the aforementioned pressure-molded body suffers from problems such as the active material delaminating during charge-discharge cycles, leading to a significant decrease in capacity. Therefore, techniques are being investigated to improve moldability by adding binder components to the mixture (see, for example, Patent Documents 1-3).

Japanese Patent Application Publication No. 11-86899 Special Publication No. 7-87045 International Publication No. 2009/107784

It is believed that moldability can be improved by adding a binder component consisting of the polymer compounds disclosed in the above-mentioned Patent Documents 1 to 3. However, because the surface of the solid electrolyte is covered with the polymer compound, ion conduction between solid electrolytes is easily inhibited. Furthermore, it is not possible to satisfy the high level of cycle life characteristics required for modern all-solid-state secondary batteries, and further improvements have been requested.

Several aspects of the present invention provide a binder for all-solid-state secondary batteries that can produce all-solid-state secondary batteries with excellent adhesion and ionic conductivity, and that can improve the cycle life characteristics of the all-solid-state secondary batteries.

This invention was made to solve at least some of the above-mentioned problems and can be realized in any of the following embodiments.

One embodiment of the binder for all-solid-state secondary batteries according to the present invention is:
It has aromatic vinyl units based on aromatic vinyl compounds and conjugated diene units based on conjugated diene compounds,
The compound, represented by the following general formula (1), contains a functional group derived from a denaturing initiator, which is a reaction product of an organometallic compound.
It contains a conjugated diene copolymer (A).
(In formula (1) above, _R1 to _R3 are each independently hydrogen, a C1-C30 alkyl group, a C2-C30 alkenyl group, a C2-C30 alkynyl group, a C1-C30 heteroalkyl group, a C2-C30 heteroalkenyl group, a C2-C30 heteroalkynyl group, a C5-C30 cycloalkyl group, a C6-C30 aryl group, or a C3-C30 heterocyclic group. _R4 is a single bond, a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C5-C20 arylene group. Here, the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. ₅ is an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, a heteroalkyl group having 1 to 30 carbon atoms, a heteroalkenyl group having 2 to 30 carbon atoms, a heteroalkynyl group having 2 to 30 carbon atoms, a cycloalkyl group having 5 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heterocyclic group having 3 to 30 carbon atoms, or a functional group represented by the following general formula (1a) or general formula (1b). n is an integer from 1 to 5, and at least one of R ₅ is a functional group represented by the following general formula (1a) or general formula (1b). If n is an integer from 2 to 5, the multiple R _5s may be the same or different from each other.
(In the above general formula (1a), R ₆ is a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C6-C20 arylene group. Here, the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. _{R 7} and R ₈ are each independently a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group substituted with or unsubstituted C1-C20 alkylene group. ₉ is hydrogen, a C1-C30 alkyl group, a C2-C30 alkenyl group, a C2-C30 alkynyl group, a C1-C30 heteroalkyl group, a C2-C30 heteroalkenyl group, a C2-C30 heteroalkynyl group, a C5-C30 cycloalkyl group, a C6-C30 aryl group, or a C3-C30 heterocyclic group. X is an N, O, or S atom; if X is O or S, _R9 does not exist.
(In the above general formula (1b), R ₁₀ is a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C6-C20 arylene group. Here, the substituents are C1-C10 alkyl groups, C5-C10 cycloalkyl groups, or C6-C20 aryl groups. _{R 11} and R ₁₂ are, independently, C1-C30 alkyl groups, C2-C30 alkenyl groups, C2-C30 alkynyl groups, C1-C30 heteroalkyl groups, C2-C30 heteroalkenyl groups, C2-C30 heteroalkynyl groups, C5-C30 cycloalkyl groups, C6-C30 aryl groups, or C3-C30 heterocyclic groups.)

In one embodiment of the binder for the all-solid-state secondary battery,
The conjugated diene copolymer (A) may further contain a functional group derived from a modifying agent represented by the following general formula (2) or the following general formula (3).
(In formula (2) above, R ₂₀ is a single bond or an alkylene group having 1 to 10 carbon atoms. _{R 21} and R ₂₂ are each independently an alkyl group having 1 to 10 carbon atoms. _{R 23} is a single bond or an alkylene group having 1 to 10 carbon atoms. _{R 24} is a divalent, trivalent, or tetravalent alkylsilyl group substituted with hydrogen, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms. a is an integer between 2 and 3. c is an integer between 1 and 3, b is an integer between 0 and 2, and b + c = 3.)
(In formula (3) above, _A1 and _A2 are each independently an alkylene group having 1 to 20 carbon atoms. _R25 to _R28 are each independently an alkyl group having 1 to 20 carbon atoms. _L1 to _L4 are each independently a divalent, trivalent, or tetravalent alkylsilyl group substituted with an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 20 carbon atoms.)

In one embodiment of the binder for the all-solid-state secondary battery,
The conjugated diene copolymer (A) may have a bound styrene content of 5 to 50%.

In one embodiment of the binder for the all-solid-state secondary battery,
The functional group content in the conjugated diene copolymer (A) can be 0.0005 mol/kg or more and 0.2 mol/kg or less.

In one embodiment of the binder for the all-solid-state secondary battery,
The ratio (Mw/Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the conjugated diene copolymer (A) can be 3 or less.

One embodiment of the binder composition for all-solid-state secondary batteries according to the present invention is:
The invention comprises a binder for all-solid-state secondary batteries according to any of the above embodiments, and a liquid medium (B),
The liquid medium (B) is at least one selected from the group consisting of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ketones, esters, and ethers.

In one embodiment of the binder composition for all-solid-state secondary batteries,
The conjugated diene copolymer (A) may be dissolved in the liquid medium (B).

One embodiment of the slurry for all-solid-state secondary batteries according to the present invention is:
The present invention contains a binder composition for all-solid-state secondary batteries according to the above embodiment, and a solid electrolyte.

In one embodiment of the slurry for the all-solid-state secondary battery,
The solid electrolyte may contain a sulfide-based solid electrolyte or an oxide-based solid electrolyte.

One embodiment of the all-solid-state secondary battery according to the present invention is:
It comprises at least a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer,
At least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is a layer formed by applying and drying the slurry for an all-solid-state secondary battery according to the above embodiment.

One embodiment of the solid electrolyte sheet for all-solid-state secondary batteries according to the present invention is:
The substrate has a layer formed by applying and drying the slurry for all-solid-state secondary batteries according to the above embodiment.

One embodiment of the all-solid-state secondary battery according to the present invention is:
It comprises at least a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer,
At least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is a layer formed from a solid electrolyte sheet for an all-solid-state secondary battery according to the above embodiment.

One embodiment of the method for manufacturing a solid electrolyte sheet for an all-solid-state secondary battery according to the present invention is:
The process includes applying the slurry for the all-solid-state secondary battery according to the above embodiment onto a substrate and drying it.

One aspect of the method for manufacturing an all-solid-state secondary battery according to the present invention is:
An all-solid-state secondary battery is manufactured by a method for manufacturing a solid electrolyte sheet for an all-solid-state secondary battery according to the above embodiment.

The binder for all-solid-state secondary batteries according to the present invention enables the fabrication of all-solid-state secondary batteries with excellent adhesion and ion conductivity, and provides all-solid-state secondary batteries with excellent cycle life characteristics.

The following describes preferred embodiments of the present invention in detail. It should be understood that the present invention is not limited to the embodiments described below, but also includes various modifications that do not alter the essence of the invention.

In this specification, "(meth)acrylic acid" refers to "acrylic acid" or "methacrylic acid."

In this specification, numerical ranges described as "X to Y" are interpreted as including the numerical value X as the lower limit and the numerical value Y as the upper limit.

1. Binder for All-Solid-State Secondary Batteries The binder for all-solid-state secondary batteries according to one embodiment of the present invention contains a conjugated diene copolymer (A) which has aromatic vinyl units based on an aromatic vinyl compound and conjugated diene units based on a conjugated diene compound, and contains functional groups derived from a modifying initiator which is a reaction product of a compound represented by the following general formula (1) and an organometallic compound.

The following describes the structure, manufacturing method, and physical properties of the conjugated diene copolymer (A).

1.1. Structure of Conjugated Diene Copolymer (A) The conjugated diene copolymer (A) has aromatic vinyl units based on an aromatic vinyl compound and conjugated diene units based on a conjugated diene compound, and contains a functional group at one end derived from a modifying initiator, which is a reaction product of a compound represented by the following general formula (1) and an organometallic compound.

In formula (1) above, _R1 to _R3 are each independently hydrogen, a C1-C30 alkyl group, a C2-C30 alkenyl group, a C2-C30 alkynyl group, a C1-C30 heteroalkyl group, a C2-C30 heteroalkenyl group, a C2-C30 heteroalkynyl group, a C5-C30 cycloalkyl group, a C6-C30 aryl group, or a C3-C30 heterocyclic group. _R4 is a single bond, a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C5-C20 arylene group. Here, the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. _R5 is an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, a heteroalkyl group having 1 to 30 carbon atoms, a heteroalkenyl group having 2 to 30 carbon atoms, a heteroalkynyl group having 2 to 30 carbon atoms, a cycloalkyl group having 5 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heterocyclic group having 3 to 30 carbon atoms, or a functional group represented by the following general formula (1a) or general formula (1b). n is an integer from 1 to 5, and at least one of _R5 is a functional group represented by the following general formula (1a) or general formula (1b). When n is an integer from 2 to 5, multiple _R5s may be the same or different from each other.

In the above general formula (1a), R ₆ is a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C6-C20 arylene group. Here, the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. R ₇ and R ₈ are each independently a C1-C20 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group, or an unsubstituted C1-C20 alkylene group. _R9 is hydrogen, a C1-C30 alkyl group, a C2-C30 alkenyl group, a C2-C30 alkynyl group, a C1-C30 heteroalkyl group, a C2-C30 heteroalkenyl group, a C2-C30 heteroalkynyl group, a C5-C30 cycloalkyl group, a C6-C30 aryl group, or a C3-C30 heterocyclic group. X is an N, O, or S atom, and if X is O or S, _R9 does not exist.

In the above general formula (1b), R ₁₀ is a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C6-C20 arylene group. Here, the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. _{R 11} and R ₁₂ are, independently, a C1-C30 alkyl group, a C2-C30 alkenyl group, a C2-C30 alkynyl group, a C1-C30 heteroalkyl group, a C2-C30 heteroalkenyl group, a C2-C30 heteroalkynyl group, a C5-C30 cycloalkyl group, a C6-C30 aryl group, or a C3-C30 heterocyclic group.

The conjugated diene copolymer (A) preferably further contains a functional group derived from a modifying agent represented by the following general formula (2) or general formula (3) at another end.

In formula (2) above, R ₂₀ is a single bond or an alkylene group having 1 to 10 carbon atoms. _{R 21} and R ₂₂ are each independently an alkyl group having 1 to 10 carbon atoms. _{R 23} is a single bond or an alkylene group having 1 to 10 carbon atoms. R ₂₄ is a divalent, trivalent, or tetravalent alkylsilyl group substituted with hydrogen, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms. a is an integer between 2 and 3. c is an integer between 1 and 3, b is an integer between 0 and 2, and b + c = 3.

In formula (3) above, _A1 and _A2 are each independently an alkylene group having 1 to 20 carbon atoms. _R25 to _R28 are each independently an alkyl group having 1 to 20 carbon atoms. _L1 to _L4 are each independently a divalent, trivalent, or tetravalent alkylsilyl group substituted with an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 20 carbon atoms.

Examples of aromatic vinyl compounds include styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, 1-vinyl-5-hexylnaphthalene, 3-(2-pyrrolidinoethyl)styrene, 4-(2-pyrrolidinoethylethyl)styrene, and 3-(2-pyrrolidino-1-ethylmethylethyl)-α-methylstyrene, and one or more selected from these can be used.

Examples of conjugated diene compounds include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1,3-butadiene, and 2-halo-1,3-butadiene. One or more of these can be used.

Furthermore, the conjugated diene copolymer (A) may also be a copolymer further comprising aromatic vinyl units based on an aromatic vinyl compound, conjugated diene units based on a conjugated diene compound, and repeating units derived from a diene monomer having 1 to 10 carbon atoms. The repeating units derived from the diene monomer may be repeating units derived from a diene monomer different from the conjugated diene compound. An example of a diene monomer different from the conjugated diene compound is 1,2-butadiene. When the conjugated diene copolymer (A) is a copolymer further comprising a diene monomer, the content of repeating units derived from the diene monomer is preferably greater than 0 to 1% by mass, more preferably greater than 0 to 0.1% by mass, even more preferably greater than 0 to 0.01% by mass, and particularly preferably greater than 0 to 0.001% by mass. When the content of repeating units derived from the diene monomer is within the above range, gel formation may be prevented.

The conjugated diene copolymer (A) is preferably a random copolymer. When the conjugated diene copolymer (A) is a random copolymer, it has the effect of having an excellent balance between its various physical properties. Here, a random copolymer means one in which the repeating units constituting the copolymer are arranged in a disordered manner.

The conjugated diene copolymer (A) may exhibit a unimodal molecular weight distribution curve obtained by gel permeation chromatography (GPC). This means that the conjugated diene copolymer (A) has a uniform molecular weight distribution, as shown by the polymer polymerized by continuous polymerization.

Generally, when a conjugated diene copolymer (A) is produced by a batch polymerization method and subjected to a modification reaction, the molecular weight distribution curve of the modified conjugated diene copolymer produced has a multi-peak molecular weight distribution curve of bimodal or greater. Specifically, in the case of batch polymerization, the polymerization reaction starts after all the raw materials have been added, and chain growth can occur simultaneously from starting points generated by multiple initiators. Therefore, the growth of each chain is generally uniform, and the molecular weight of the polymer chain produced is constant, resulting in a unimodal form with a considerably narrow molecular weight distribution. However, when a modification agent is added to cause a modification reaction, two types of cases can occur: "no modification occurs" and "modification and coupling occur." As a result, two groups with large differences in molecular weight are formed between the polymer chains, so the molecular weight distribution curve forms a multi-peak molecular weight distribution curve with two or more peaks. On the other hand, in the case of continuous polymerization, unlike batch polymerization, the start of the reaction and the addition of raw materials occur continuously, so the starting point where the reaction begins and the point at which the product is formed are different. As a result, polymerization can begin at various stages of the reaction, including the early stages, intermediate stages, and final stages. Therefore, upon completion of the polymerization reaction, polymer chains with diverse molecular weights are produced. Consequently, no single dominant peak appears in the molecular weight distribution curve; instead, a broad, single peak is represented. Even if chains whose polymerization began at the final stage are coupled, their molecular weight can be similar to that of chains whose polymerization began at the early stages, thus maintaining the diversity of molecular weight distribution.

However, even when a conjugated diene copolymer (A) is produced and modified using a batch polymerization method, the modification conditions can be adjusted to achieve a unimodal form. However, in this case, the entire polymer must either be uncoupled or entirely coupled; otherwise, a unimodal molecular weight distribution curve cannot be observed.

Furthermore, as mentioned above, even if the conjugated diene copolymer (A) is produced by a batch polymerization method, if the molecular weight distribution curve of the conjugated diene copolymer (A) shows a unimodal distribution, and the entire polymer is coupled, the processability may be poor because only polymers with similar molecular weights exist, and the compounding properties may be poor because the number of interacting functional groups decreases due to coupling. On the other hand, if the entire polymer is not coupled, the interaction between the polymer terminal functional groups becomes dominant during processing, which can result in very poor processability. Therefore, when adjusting the polymer to have a unimodal molecular weight distribution curve while producing it by a batch polymerization method, there is a problem of reduced processability and compounding properties of the produced conjugated diene copolymer (A), and the processability in particular may decrease significantly.

The coupling ability of a conjugated diene copolymer (A) can be determined by its coupling number (C.N.). Here, the coupling number is a value that depends on the number of functional groups that the polymer can bond to in the modifying agent after the polymer has been modified. That is, it represents the ratio of polymers with no coupling between polymer chains (only terminal modification) to polymers with multiple polymer chains coupled to a single modifying agent, and can have a range of 1 ≤ C.N. ≤ F. Here, F represents the number of functional groups in the modifying agent that can react with the active polymer ends. In other words, a conjugated diene copolymer (A) with a coupling number of 1 means that not all polymer chains are coupled, while a conjugated diene copolymer (A) with a coupling number of F means that all polymer chains are coupled.

Therefore, the conjugated diene copolymer (A) may have a unimodal molecular weight distribution curve, but its coupling number may be greater than 1 and less than the number of functional groups of the modifier used (1 < C.N. < F).

The Si content of the conjugated diene copolymer (A) is preferably 50 ppm or more by weight, more preferably 100 ppm or more, even more preferably 100 ppm to 10,000 ppm, and particularly preferably 100 ppm to 5,000 ppm. Conjugated diene copolymers (A) with a Si content within the above range may exhibit excellent mechanical properties such as tensile and viscoelastic properties. The Si content refers to the content of Si atoms present in the conjugated diene copolymer (A). These Si atoms may originate from functional groups derived from the modifier.

Furthermore, the nitrogen content of the conjugated diene copolymer (A) is preferably 50 ppm or more by weight, more preferably 100 ppm or more, even more preferably 100 ppm to 10,000 ppm, and particularly preferably 100 ppm to 5,000 ppm. Conjugated diene copolymers (A) with an nitrogen content within the above range may exhibit excellent mechanical properties such as tensile and viscoelastic properties. The nitrogen content refers to the content of nitrogen atoms present in the conjugated diene copolymer (A). These nitrogen atoms may originate from functional groups derived from the modifying agent.

The Si content was measured via ICP analysis. This ICP analysis can be performed using an inductively coupled plasma emission spectrometer (ICP-OES; Optima 7300DV). The measurement method is as follows:
First, approximately 0.7 g of the sample was placed in a platinum crucible, approximately 1 mL of concentrated sulfuric acid (98% by weight) was added, and the mixture was heated at 300°C for 3 hours. The sample was then subjected to ashing in an electric furnace using the program described in steps 1 to 3 below.
1) Step 1: Initial temperature 0°C, heating rate 180°C/hour, holding time 180°C for 1 hour. 2) Step 2: Initial temperature 180°C, heating rate 85°C/hour, holding time 370°C for 2 hours. 3) Step 3: Initial temperature 370°C, heating rate 47°C/hour, holding time 510°C for 3 hours.
Next, 1 mL of concentrated nitric acid (48% by weight) and 20 μL of concentrated hydrofluoric acid (50% by weight) were added to the residue. The platinum crucible was sealed and shaken for at least 30 minutes. Then, 1 mL of boric acid was added to the sample and stored at 0°C for at least 2 hours. After that, the sample was diluted with 30 mL of ultrapure water, and the resulting ashing was measured.

The nitrogen content was measured via the NSX analytical method. This NSX analytical method can be performed using a trace nitrogen quantitative analyzer (NSX-2100H). The measurement method is as follows:
A trace nitrogen quantitative analyzer (Horizontal Furnace, PMT & Nitrogen Detector) was attached, and the carrier gas flow rates were set to Ar at 250 mL/min, _O2 at 350 mL/min, and ozonizer at 300 mL/min. After setting the heater to 800°C, the analyzer was allowed to stabilize for approximately 3 hours. After the analyzer stabilized, calibration curves were created using Nitrogen Standard (AccuStandard S-22750-01-5 ml) for calibration ranges of 5 ppm, 10 ppm, 50 ppm, 100 ppm, and 500 ppm. After obtaining the Area corresponding to each concentration, a straight line was created using the concentration-to-Area ratio. Subsequently, a ceramic boat containing 20 mg of sample was placed on the AutoSampler of the analyzer and measured to obtain the Area. The N content was calculated using the Area of the obtained sample and the calibration curve.

The sample used in the NSX analysis method is a sample of a conjugated diene copolymer (A) obtained by placing it in steam-heated hot water, stirring, and removing the solvent. This sample may also be one from which residual monomers and residual modifiers have been removed. Furthermore, if oil has been added to the sample, the sample may be one from which the oil has been extracted (removed).

Furthermore, the Mooney relaxation rate of the conjugated diene copolymer (A), measured at 100°C, is preferably 0.7 or higher, more preferably 0.7 to 3.0, even more preferably 0.7 to 2.5, and particularly preferably 0.7 to 2.0.

Here, the Mooney relaxation rate represents the change in stress expressed in response to the same amount of modification, and was measured using a Mooney viscometer. Specifically, the Mooney relaxation rate was obtained by using a Monsanto MV2000E Large Rotor at 100°C and a Rotor Speed of 2 ± 0.02 rpm. After leaving the polymer at room temperature (23 ± 5°C) for 30 minutes or more, 27 ± 3 g was taken and filled into the die cavity. The platen was operated to apply torque, and the Mooney viscosity was measured. Subsequently, the slope value of the change in Mooney viscosity that appeared as the torque decreased was measured and obtained as the absolute value.

The Mooney relaxation rate can be used as an indicator of the branched structure of a conjugated diene copolymer (A). For example, when comparing polymers with equivalent Mooney viscosity, a higher degree of branching results in a lower Mooney relaxation rate, thus it can be used as an indicator of the degree of branching.

The Mooney viscosity of the conjugated diene copolymer (A) is preferably 30 or higher, more preferably 40 to 150, and particularly preferably 40 to 140 at 100°C. When the Mooney viscosity of the conjugated diene copolymer (A) falls within this range, it may exhibit excellent processability and productivity.

Furthermore, the shrinkage factor (g') of the conjugated diene copolymer (A), as determined by gel transmission chromatography light scattering measurement with a viscosity detector, is preferably 1.0 or higher, more preferably 1.0 to 3.0, and particularly preferably 1.0 to 1.3.

The shrinkage factor (g') determined by gel transmission chromatography light scattering is the ratio of the intrinsic viscosity of a branched polymer to the intrinsic viscosity of a linear polymer with the same absolute molecular weight. It can be used as an indicator of the branching structure of a branched polymer, i.e., an indicator of the proportion of branching. For example, the number of branches in a polymer tends to increase as the shrinkage factor decreases. Therefore, when comparing polymers with equivalent absolute molecular weights, a higher branching ratio results in a lower shrinkage factor, and thus it can be used as an indicator of the degree of branching.

The shrinkage factor was calculated based on solution viscosity and light scattering by measuring chromatograms using a gel chromatography light scattering analyzer equipped with a viscosity detector. Specifically, using a GPC light scattering analyzer with two connected columns packed with polystyrene gel, the absolute molecular weight and the intrinsic viscosity corresponding to each absolute molecular weight were obtained. After calculating the intrinsic viscosity of the linear polymer corresponding to the absolute molecular weight, the shrinkage factor was determined as the ratio of the intrinsic viscosities corresponding to each absolute molecular weight. The shrinkage factor was determined by injecting a sample into a GPC light scattering analyzer (Viscotec TDAmax, Malvern), which was equipped with a light scattering detector and a viscometer, with two columns packed with polystyrene gel connected as a packing material. The absolute molecular weight was obtained from the light scattering detector, and the intrinsic viscosity [η] for the absolute molecular weight was obtained from the light scattering detector and the viscometer. Then, the intrinsic viscosity [η] ₀ of the linear polymer for the absolute molecular weight was calculated from the following formula (4), and the average value of the ratio of the intrinsic viscosities corresponding to each absolute molecular weight ([η]/[η] ₀ ) was shown as the shrinkage factor. At this time, the eluent was a mixed solution of tetrahydrofuran and N,N,N',N'-tetramethylethylenediamine (prepared by mixing 20 mL of N,N,N',N'-tetramethylethylenediamine with 1 L of tetrahydrofuran), the column was a PLOlexix (Agilent), and the measurement was performed under conditions of an oven temperature of 40°C and a THF flow rate of 1.0 mL/min. The sample was prepared by dissolving 15 mg of polymer in 10 mL of THF.

[η] ₀ = 10 ^-3.883 M ^0.771 ...(4)
(In formula (4) above, M is the absolute molecular weight.)

The 1,2-vinyl bond content of the conjugated diene copolymer (A) is preferably 5% to 60% by mass, more preferably 10% to 55% by mass, and particularly preferably 15% to 50% by mass. Here, the 1,2-vinyl bond content refers to the content of 1,2-added conjugated diene monomers (not 1,4-added) per 100% by mass of the conjugated diene copolymer (A), which has aromatic vinyl units based on an aromatic vinyl compound and conjugated diene units based on a conjugated diene compound.

On the other hand, the modification initiator is preferably one produced by reacting a compound represented by the general formula (1) with an organometallic compound, and which can initiate polymerization while simultaneously introducing a functional group to one end of the polymer chain formed by polymerization.

In the compound represented by the general formula (1) above, _R1 to _R3 are preferably each independently hydrogen, a C1-C10 alkyl group, a C2-C10 alkenyl group, or a C2-C10 alkynyl group. _R4 is preferably a single bond or an unsubstituted C1-C10 alkylene group. _R5 is preferably a C1-C10 alkyl group, a C2-C10 alkenyl group, a C2-C10 alkynyl group, or a functional group represented by the general formula (1a) or (1b) above.

In the above general formula (1a), R ₆ is preferably an unsubstituted alkylene group having 1 to 10 carbon atoms. _{R 7} and R ₈ are each preferably unsubstituted alkylene groups having 1 to 10 carbon atoms. _{R 9} is preferably an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heterocyclic group having 3 to 20 carbon atoms.

In the above general formula (1b), R ₁₀ is preferably an unsubstituted alkylene group having 1 to 10 carbon atoms. _{R 11} and R ₁₂ are each preferably independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heterocyclic group having 3 to 20 carbon atoms.

The compound represented by the above general formula (1) is more preferably a compound represented by the following formulas (1-1) to (1-3).

The organometallic compound is preferably an organoalkali metal compound. Examples of organoalkali metal compounds include organolithium compounds, organosodium compounds, organotassium compounds, organorubidium compounds, and organocesium compounds, and one or more selected from these can be used.

Specific examples of organometallic compounds include methyllithium, ethyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, n-decyllithium, tert-octyllithium, phenyllithium, 1-naphthyllithium, n-eicolithium, 4-butylphenyllithium, 4-tolylllithium, cyclohexyllithium, 3,5-di-n-heptylcyclohexyllithium, and 4-cyclopentyllithium, and one or more selected from these can be used.

Furthermore, the modifying agent is used to modify the remaining end of the conjugated diene copolymer (A). A specific example of a modifying agent is a silica affinity modifying agent. A silica affinity modifying agent may contain a silica affinity functional group within the compound used as the modifying agent. Since the silica affinity functional group exhibits excellent affinity for fillers, particularly silica-based fillers, it may be a functional group that allows interaction between the silica-based filler and the functional group derived from the modifying agent.

The denaturing agent may be a compound represented by the general formula (2) above. In formula (2) above, R ₂₀ is preferably a single bond or an alkylene group having 1 to 5 carbon atoms. _{R 21} and R ₂₂ are each preferably an alkyl group having 1 to 5 carbon atoms independently. R ₂₃ is preferably a single bond or an alkylene group having 1 to 5 carbon atoms. R ₂₄ is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a tetravalent alkylsilyl group substituted with an alkyl group having 1 to 5 carbon atoms. a is preferably an integer of 2 or 3. c is preferably an integer of 1 to 3, and b is preferably an integer of 0 to 2, in which case b + c = 3 is preferred.

Specific examples of compounds represented by the above general formula (2) include N,N-bis(3-(dimethoxy(methyl)silyl)propyl)-methyl-1-amine, N,N-bis(3-(diethoxy(methyl)silyl)propyl)-methyl-1-amine, N,N-bis(3-(trimethoxysilyl)propyl)-methyl-1-amine, N,N-bis(3-(triethoxysilyl)propyl)-methyl-1-amine, and N,N-diethyl-3-(trimethoxysilyl)propane Examples include -1-amine, N,N-diethyl-3-(triethoxysilyl)propane-1-amine, tri(trimethoxysilyl)amine, tri(3-(trimethoxysilyl)propyl)amine, N,N-bis(3-(diethoxy(methyl)silyl)propyl)-1,1,1-trimethylsilaneamine, and 3-(dimethoxy(methyl)silyl)-N,N-diethylpropane-1-amine, and one or more selected from these can be used.

Furthermore, the modifying agent may be a compound represented by the above general formula (3). In formula (3), _A1 and _A2 are preferably each independently an alkylene group having 1 to 10 carbon atoms. _R25 to _R28 are preferably each independently an alkyl group having 1 to 10 carbon atoms. _L1 to _L4 are preferably each independently a tetravalent alkylsilyl group substituted with an alkyl group having 1 to 5 carbon atoms, or an alkyl group having 1 to 10 carbon atoms.

Specific examples of compounds represented by the above general formula ( 3 ) include 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3'-( 1,1,3,3-Tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine),3,3'-(1,1,3,3-Tetramethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1-amine),3,3'-(1,1,3,3-Tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine),3,3'-(1,1,3,3-Tetrapropoxydisiloxane-1,3- Diyl)bis(N,N-diethylpropane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1-amine) ,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1-amine),3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1-amine),3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine),3,3'-(1,1,3,3-tetramethoxydisiloxane-1 ,3-diyl)bis(N,N-dipropylmethane-1-amine),3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine),3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethane-1-amine),3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine) ), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethane-1-amine), N,N'-((1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(1,1,1-trimethyl-N-(trimethylsilyl)silaneamine), N,N'-((1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis Bis(1,1,1-trimethyl-N-(trimethylsilyl)silaneamine), N,N'-((1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(1,1,1-trimethyl-N-(trimethylsilyl)silaneamine), N,N'-((1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(1,1,1-trimethyl-N-phenylsilaneamine Examples include N,N'-((1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(1,1,1-trimethyl-N-phenylsilaneamine), and N,N'-((1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(1,1,1-trimethyl-N-phenylsilaneamine), and one or more selected from these can be used.

As described above, the conjugated diene copolymer (A) may have a specific structure and a unique molecular weight distribution and morphology. The structure of such a conjugated diene copolymer (A) may be expressed in terms of physical properties such as shrinkage factor, Mooney relaxation rate, and coupling number. The molecular weight distribution and its morphology may be expressed in terms of molecular weight distribution values, the morphology of the molecular weight distribution curve, and the coupling number. Modification of both ends by a denaturing agent and a denaturing initiator can affect the structure, molecular weight distribution, and its morphology. The parameters and molecular weight distribution characteristics that describe the structure of such a polymer can be satisfied by the manufacturing method described later.

1.2. Method for producing conjugated diene copolymer (A) The method for producing conjugated diene copolymer (A) will be described below.

The method for producing a conjugated diene copolymer (A) includes the steps of: (S1) polymerizing a conjugated diene compound and an aromatic vinyl compound in a hydrocarbon solvent in the presence of a modifying initiator to produce an active polymer into which functional groups derived from the modifying initiator have been introduced; and (S2) reacting or coupling the active polymer produced in step (S1) with a modifying agent represented by the general formula (2) or (3). Step (S1) is carried out continuously in two or more polymerization reactors, and the polymerization conversion rate in the first of the polymerization reactors is 50% or less. The modifying initiator is a reaction product produced by reacting a compound represented by the general formula (1) with an organometallic compound.

Examples of hydrocarbon solvents include n-pentane, n-hexane, n-heptane, isooctane, cyclohexane, toluene, benzene, and xylene, and one or more selected from these can be used. The same applies to conjugated diene compounds and aromatic vinyl compounds as described above.

The denaturation initiator can be used in a ratio of preferably 0.01 mmol to 10 mmol, more preferably 0.05 mmol to 5 mmol, even more preferably 0.1 mmol to 2 mmol, even more preferably 0.1 mmol to 1 mmol, and particularly preferably 0.15 mmol to 0.8 mmol, per 100 g of total monomers.

The polymerization in step (S1) is preferably anionic polymerization. For example, living anionic polymerization, where an anionic active site is present at the polymerization end due to an anionic growth polymerization reaction, is one such example. Furthermore, the polymerization in step (S1) may be temperature-increasing polymerization, isothermal polymerization, or constant-temperature polymerization (adiabatic polymerization). Constant-temperature polymerization is a polymerization method that includes a step in which polymerization is carried out using the reaction heat of the material itself without adding any additional heat after the modification initiator has been added. Temperature-increasing polymerization is a polymerization method in which the temperature is increased by adding heat after the modification initiator has been added, or by removing heat to maintain a constant temperature of the polymer.

Furthermore, in step (S1), a diene compound having 1 to 10 carbon atoms may be added in addition to the conjugated diene compound for polymerization. In this case, it may be possible to prevent gel formation on the reactor walls during prolonged operation. 1,2-butadiene is preferred as the diene compound.

The polymerization in step (S1) is preferably carried out at a temperature range of 80°C or lower, more preferably -20°C to 80°C, even more preferably 0°C to 80°C, even more preferably 0°C to 70°C, and particularly preferably 10°C to 70°C. Narrowing the molecular weight distribution of the polymer within this temperature range can result in superior improvement of its physical properties.

The active polymer produced by step (S1) is a polymer in which a polymer anion and an organometallic cation are bonded.

This manufacturing method is carried out by a continuous polymerization method using multiple reactors, including two or more polymerization reactors and modification reactors. Specifically, step (S1) may be carried out continuously in two or more polymerization reactors, including the first reactor, and the number of polymerization reactors may be appropriately determined depending on the reaction conditions and environment. A continuous polymerization method refers to a reaction process in which reactants are continuously supplied to the reactors and the generated reaction products are continuously discharged. Continuous polymerization methods offer excellent productivity and processability, and the resulting polymer may exhibit excellent uniformity.

When continuously producing an active polymer in a polymerization reactor, the polymerization conversion rate in the first reactor is preferably 50% or less, more preferably 10% to 50%, and particularly preferably 20% to 50%. When the polymerization conversion rate in the first reactor is within this range, side reactions occurring during polymer formation are suppressed, and a linear polymer structure can be induced during polymerization. This allows for a narrower molecular weight distribution of the polymer, which can lead to improved physical properties. The polymerization conversion rate can be adjusted by the reaction temperature, the residence time in the reactor, and other factors.

The polymerization conversion rate can be determined by measuring the solid concentration of the polymer solution phase containing the polymer during polymerization. Specifically, a cylindrical container is attached to the outlet of each polymerization reactor to secure the polymer solution, and a certain amount of polymer solution is filled into the cylindrical container. Then, the cylindrical container is separated from the reactor, and the weight of the cylinder filled with the polymer solution (A) is measured. The polymer solution in the cylindrical container is then transferred to an aluminum container, and the weight of the cylindrical container from which the polymer solution has been removed (B) is measured. Finally, the aluminum container containing the polymer solution is dried in an oven at 140°C for 30 minutes, and after measuring the weight of the dried polymer (C), the polymerization conversion rate can be calculated using the following formula (5).

Polymerization conversion rate (%) = weight (C) / [(weight (A) - weight (B)) × total solids content of each reactor (weight %), TSC)] ..... (5)

The polymerized product in the first reactor may be sequentially transferred to the polymerization reactor before the modification reactor, and polymerization may proceed until the polymerization conversion rate reaches 95% or higher. Furthermore, the polymerization conversion rates in each reactor, from the first reactor to the second reactor, or from the second reactor to the polymerization reactor before the modification reactor, may be appropriately adjusted for each reactor to control the molecular weight distribution.

In step (S1) above, when producing the active polymer, the polymer residence time in the first reactor is preferably 1 to 40 minutes, more preferably 1 to 30 minutes, and particularly preferably 5 to 30 minutes. When the polymer residence time in the first reactor is within the above range, it becomes easier to adjust the polymerization conversion rate. This makes it possible to narrow the molecular weight distribution of the polymer, which can lead to excellent improvement in physical properties.

In this specification, “polymer” means an intermediate polymer in which polymerization is being carried out in each reactor during step (S1) prior to the completion of step (S1) or step (S2) and the acquisition of the active polymer or conjugated diene copolymer (A), and means a polymer with a polymerization conversion rate of less than 95% that is being polymerized in the reactor.

The molecular weight distribution (Mw/Mn) of the active polymer produced in step (S1) is preferably less than 1.5, more preferably 1.0 or more and less than 1.5, and particularly preferably 1.1 or more and less than 1.5. When the molecular weight distribution of the active polymer falls within this range, the molecular weight distribution of the conjugated diene copolymer (A) produced via a modification reaction or coupling with a modification agent becomes narrower, which can result in superior improvement of physical properties.

The polymerization in step (S1) may be carried out with the inclusion of a polar additive. The polar additive can be added in a ratio of preferably 0.001 g to 50 g, more preferably 0.001 g to 10 g, and particularly preferably 0.005 g to 0.1 g, per 100 g of total monomers. Alternatively, the polar additive can be added in a ratio of preferably 0.001 g to 10 g, more preferably 0.005 g to 5 g, and particularly preferably 0.005 g to 4 g, per 1 mmol of total modification initiator.

Examples of polar additives include tetrahydrofuran, 2,2-di-(2-tetrahydrofurfuryl)propane, diethyl ether, cycloamal ether, dipropyl ether, ethylene methyl ether, ethylene dimethyl ether, diethyl glycol, dimethyl ether, tert-butoxyethoxyethane, bis(3-dimethylaminoethyl) ether, (dimethylaminoethyl) ethyl ether, trimethylamine, triethylamine, tripropylamine, N,N,N',N'-tetramethylethylenediamine, sodium mentholate, and 2-ethyltetrahydrofurfuryl ether. One or more of these can be selected and used. Among these, triethylamine, tetramethylethylenediamine, sodium mentholate, or 2-ethyltetrahydrofurfuryl ether are preferred. When polar additives are included, the difference in reaction rates between the conjugated diene compound and the aromatic vinyl compound during copolymerization can be compensated for, potentially leading to the easy formation of a random copolymer.

The reaction or coupling in step (S2) may be carried out in a denaturing reactor. In this case, the denaturing agent can be used in an amount of 0.01 mmol to 10 mmol per 100 g of total monomers. Furthermore, the denaturing agent can be used in a molar ratio of preferably 1:0.1 to 10, more preferably 1:0.1 to 5, and particularly preferably 1:0.1 to 3, per mole of the denaturing initiator in step (S1).

Furthermore, the denaturing agent may be introduced into the denaturing reactor. Step (S2) may be carried out in the denaturing reactor. Alternatively, the denaturing agent may be introduced into a transfer section for transferring the active polymer produced in step (S1) to the denaturing reactor for carrying out step (S2). Furthermore, a reaction or coupling may proceed within the transfer section by mixing the active polymer and the denaturing agent.

1.3. Physical properties of conjugated diene copolymer (A) <Conjugated styrene content>
The lower limit of the bound styrene content of the conjugated diene copolymer (A) is preferably 5%, more preferably 8%, and particularly preferably 10%.
The upper limit of the bound styrene content is preferably 50%, more preferably 45%, and particularly preferably 40%. When the bound styrene content of the conjugated diene copolymer (A) is within the above range, both good adhesion and flexibility of the electrode can be achieved. The bound styrene content can be measured by ^1H -NMR measurement.

<Functional group>
The conjugated diene copolymer (A) may have a functional group containing at least one atom selected from the group consisting of nitrogen, oxygen, silicon, germanium, and tin atoms (hereinafter also referred to as the "specific atom"). The presence of a functional group in the conjugated diene copolymer (A) may enable the resulting all-solid-state secondary battery binder to exhibit excellent adhesion to current collectors and solid electrolyte materials.

Functional groups containing specific atoms are not particularly limited, as long as they contain at least one atom selected from the group consisting of nitrogen, oxygen, silicon, germanium, and tin atoms. Specific examples of functional groups are shown below. Functional groups containing multiple atoms from the group consisting of nitrogen, oxygen, silicon, germanium, and tin atoms are illustrated only as examples of functional groups containing one of these atoms.

Specific examples of functional groups containing nitrogen atoms include unsubstituted amino groups, monoalkylamino groups, monoarylamino groups, dialkylamino groups, diarylamino groups, alkylarylamino groups, cyclic amino groups, bis(trialkylsilyl)amino groups, cyano groups, aminocarbonyl groups, alkylaminocarbonyl groups, arylaminocarbonyl groups, imino groups, pyridyl groups, and imidazolyl groups. Among these, from the viewpoint of the adhesion of the resulting binder, amino groups are preferred, unsubstituted amino groups, monoalkylamino groups, dialkylamino groups, cyclic amino groups, and bis(trialkylsilyl)amino groups are more preferred, unsubstituted amino groups, dialkylamino groups, and cyclic amino groups are even more preferred, and unsubstituted amino groups, dimethylamino groups, and N-piperidinyl groups are particularly preferred.

Specific examples of functional groups containing oxygen atoms include hydroxyl groups, epoxy groups, carboxyl groups, ether groups, alkoxy groups, aryloxy groups, carbonyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, acid anhydride groups, and lactone groups. Among these, hydroxyl groups, epoxy groups, carboxyl groups, and acid anhydride groups are preferred from the viewpoint of the adhesion of the resulting binder, with hydroxyl groups and carboxyl groups being more preferred.

Specific examples of functional groups containing silicon atoms include, for example, alkoxysilyl groups such as unsubstituted silyl groups, alkoxysilyl groups, dialkoxysilyl groups, and trialkoxysilyl groups, and aryloxysilyl groups such as aryloxysilyl groups, diaryloxysilyl groups, and triaryloxysilyl groups. Among these, from the viewpoint of the adhesion of the resulting binder, alkoxysilyl groups are preferred, monoalkoxysilyl groups, dialkoxysilyl groups, and trialkoxysilyl groups are more preferred, and monomethoxysilyl groups, monoethoxysilyl groups, dimethoxysilyl groups, diethoxysilyl groups, trimethoxysilyl groups, and triethoxysilyl groups are particularly preferred.

Specific examples of functional groups containing germanium atoms include, for example, alkoxygelmyl groups such as unsubstituted gelmyl groups, alkoxygelmyl groups, dialkoxygelmyl groups, and trialkoxygelmyl groups, and aryloxygelmyl groups such as aryloxygelmyl groups, diaryloxygelmyl groups, and triaryloxygelmyl groups. Among these, from the viewpoint of the adhesion of the resulting binder, alkoxygelmyl groups are preferred, monoalkoxygelmyl groups, dialkoxygelmyl groups, and trialkoxygelmyl groups are more preferred, and monomethoxygelmyl groups, monoethoxygelmyl groups, dimethoxygelmyl groups, diethoxygelmyl groups, trimethoxygelmyl groups, and triethoxygelmyl groups are particularly preferred.

Specific examples of functional groups containing a tin atom include, for example, alkoxystanyl groups such as unsubstituted staniyl groups, alkoxystanyl groups, dialoxystanyl groups, and trialoxystanyl groups, and aryloxystanyl groups such as aryloxystanyl groups, diaryloxystanyl groups, and triaryloxystanyl groups. Among these, from the viewpoint of the adhesion of the resulting binder, alkoxystanyl groups are preferred, monoalkoxystanyl groups, dialoxystanyl groups, and trialoxystanyl groups are more preferred, and monomethoxystanyl groups, monoethoxystanyl groups, dimethoxystanyl groups, diethoxystanyl groups, trimethoxystanyl groups, and triethoxystanyl groups are particularly preferred.

The method for introducing a functional group containing the specific atom into the conjugated diene copolymer (A) is not particularly limited, and known methods can be used. For example, (i) a method of forming a bond by reacting a modifying agent containing the specific atom with the active end of the polymer after polymerization; (ii) a method of carrying out a polymerization reaction using a polymerization initiator containing the specific atom; (iii) a method of copolymerizing monomers containing the specific atom; and (iv) a method of reacting a compound containing the specific atom with a part of the polymer. These modifying agents, polymerization initiators, monomers, and compounds containing the specific atom either have a functional group or a group that can be converted into a functional group.

The functional group content in the conjugated diene copolymer (A) is preferably 0.0005 mol/kg or more and 0.2 mol/kg or less, more preferably 0.001 mol/kg or more and 0.15 mol/kg or less, and particularly preferably 0.005 mol/kg or more and 0.1 mol/kg or less. When the functional group content in the conjugated diene copolymer (A) is within the above range, it may exhibit an excellent balance of mechanical properties such as tensile and viscoelastic properties.

<Weight average molecular weight (Mw)>
The weight-average molecular weight (Mw) of the conjugated diene copolymer (A) is preferably 1.0 × ^10⁵ to 2.0 × ^10⁶ , more preferably 1.0 × ^10⁵ to 1.5 × ^10⁶ , and particularly preferably 1.5 × ^10⁵ to 1.0 × ^10⁶ . When the weight-average molecular weight (Mw) is above the lower limit, the adhesion of the electrode tends to improve. When the weight-average molecular weight (Mw) is below the upper limit, the flexibility of the electrode tends to be maintained. In this specification, "weight-average molecular weight (Mw)" refers to the weight-average molecular weight in polystyrene terms measured by gel permeation chromatography (GPC).

<Number average molecular weight (Mn)>
The number-average molecular weight (Mn) of the conjugated diene copolymer (A) is 1.0 × ^10⁵ to 1.5 × ^10⁶ , more preferably 1.0 × ^10⁵ to 1.0 × ^10⁶ , and particularly preferably 1.5 × ^10⁵ to 5.0 × ^10⁵ . When the number-average molecular weight (Mn) is above the lower limit, the adhesion of the electrode tends to improve. When the number-average molecular weight (Mn) is below the upper limit, the flexibility of the electrode tends to be maintained. In this specification, "number-average molecular weight (Mn)" refers to the number-average molecular weight in polystyrene terms measured by gel permeation chromatography (GPC).

<Mw/Mn>
The ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the conjugated diene copolymer (A) (Mw/Mn) is preferably 3.0 or less, more preferably 1.0 to 2.0, and particularly preferably 1.1 to 1.7. When the Mw/Mn value is within the above range, the copolymer may exhibit excellent tensile and viscoelastic properties, as well as a good balance of various physical properties.

2. Binder Composition for All-Solid-State Secondary Batteries The binder composition for all-solid-state secondary batteries according to one embodiment of the present invention contains the above-described binder for all-solid-state secondary batteries and a liquid medium (B). Hereinafter, each component contained in the binder composition for all-solid-state secondary batteries according to this embodiment will be described in detail. Note that the binder for all-solid-state secondary batteries has been described above, so a detailed explanation will be omitted.

2.1. Liquid media (B)
The liquid medium (B) is not particularly limited, but can be aliphatic hydrocarbons such as hexane, heptane, octane, decane, and dodecane; alicyclic hydrocarbons such as cyclohexane, cycloheptane, cyclooctane, and cyclodecane; aromatic hydrocarbons such as toluene, xylene, mesitylene, naphthalene, and tetralin; ketones such as 3-pentanone, 4-heptanone, methylhexyl ketone, and diisobutyl ketone; esters such as butyl acetate, butyl butyrate, methyl butanoate, butyl pentanoate, butyl hexanoate, pentyl butyrate, pentyl pentanoate, pentyl hexanoate, hexyl butyrate, hexyl pentanoate, and hexyl hexanoate; and ethers such as dibutyl ether, tetrahydrofuran, and anisole. These solvents can be used individually or in combination of two or more.

The content of the liquid medium (B) is preferably 100 to 10,000 parts by mass, more preferably 150 to 5,000 parts by mass, even more preferably 200 to 4,000 parts by mass, and particularly preferably 300 to 3,000 parts by mass, per 100 parts by mass of the conjugated diene copolymer (A). By setting the content of the liquid medium (B) within the above range, the workability when using the binder composition for all-solid-state secondary batteries and the slurry for all-solid-state secondary batteries obtained therefrom can be improved.

In the binder composition for all-solid-state secondary batteries according to this embodiment, it is preferable that the conjugated diene copolymer (A) is dissolved in the liquid medium (B). "The conjugated diene copolymer (A) is dissolved in the liquid medium (B)" means that the solubility of the conjugated diene copolymer (A) in the liquid medium (B) is 1 g or more per 100 g of the liquid medium (B). Because the conjugated diene copolymer (A) is dissolved in the liquid medium (B), the surface of the active material is easily coated by the conjugated diene copolymer (A), which has excellent flexibility and adhesion. This effectively suppresses the shedding of the active material due to expansion and contraction during charging and discharging, making it easier to obtain an all-solid-state secondary battery exhibiting good charge-discharge durability characteristics. Furthermore, this is preferable because it improves the stability of the slurry and the applicability of the slurry to the current collector.

2.2 Other Additives The binder composition for all-solid-state secondary batteries according to this embodiment may contain additives such as antioxidants and thickeners, as needed.

<Anti-aging agent>
Examples of anti-aging agents include phenolic anti-aging agents, amine anti-aging agents, quinone anti-aging agents, phosphorus anti-aging agents, sulfur anti-aging agents, and phenothiazine anti-aging agents. Among these, phenolic anti-aging agents and amine anti-aging agents are preferred. These anti-aging agents may be used individually or in combination of two or more types.

Examples of phenolic antioxidants include p-methoxyphenol, 2,6-di-tert-butyl-p-cresol, phenol, hydroquinone, p-cresol, butylhydroxyanisole, propyl gallate, chlorogenic acid, catechin, caffeic acid, genkwanin, luteolin, tocopherol, catechol, resorcinol, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, pyrogallol, 4,4'-butylidenebis(6-tert-butyl-m-cresol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), and 2,2'-methylenebis(6-tert-butyl-4-ethyl Examples include methylphenol, 4,4'-thiobis(6-tert-butyl-m-cresol), 2,5-di-tert-amylhydroquinone, styrene-phenol, 2,5-di-tert-butylhydroquinone, 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, 2,4-bis(dodecylthiomethyl)-6-methylphenol, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, and 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate.

Examples of amine-based antioxidants include aromatic amines such as 1-naphthylamine, 2-naphthylamine, phenylenediamine, 4,4'-diaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, N-isopropyl-N'-phenylbenzene-1,4-diamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline. Furthermore, other suitable amine-based antioxidants include light stabilizers (HALS), hindered amine compounds, and nitroxyl radicals (2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)).

Phosphate compounds are examples of phosphorus-based antioxidants. Sulfide compounds such as thiol compounds and pentaerythrityltetrakis (3-laurylthiopropionate) can be used as sulfide antioxidants.

When the binder composition for all-solid-state secondary batteries according to this embodiment contains an antioxidant, the content ratio of the antioxidant is preferably 0.05 to 2 parts by mass, more preferably 0.1 to 1 part by mass, and particularly preferably 0.2 to 0.8 parts by mass, based on 100 parts by mass of the total solid content of the binder composition for all-solid-state secondary batteries.

<Thickening agent>
The binder composition for all-solid-state secondary batteries according to this embodiment may contain a thickening agent, which may further improve its applicability and the charge-discharge characteristics of the resulting all-solid-state secondary battery.

Examples of thickening agents include cellulosic polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose, and hydroxypropylcellulose; poly(meth)acrylic acid; ammonium salts or alkali metal salts of the aforementioned cellulose compounds or poly(meth)acrylic acid; modified polyvinyl alcohol, polyethylene oxide; polyvinylpyrrolidone, polycarboxylic acid, starch oxide, starch phosphate, casein, various modified starches, chitin, and chitosan derivatives. Among these, cellulosic polymers are preferred.

When the binder composition for all-solid-state secondary batteries according to this embodiment contains a thickening agent, the proportion of the thickening agent is preferably 5 parts by mass or less, and more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the total solid content of the binder composition for all-solid-state secondary batteries.

2.3. Method for Preparing Binder Composition for All-Solid-State Secondary Batteries The binder composition for all-solid-state secondary batteries according to this embodiment can be prepared by adding a liquid medium (B) to a conjugated diene copolymer (A), adding other additives as necessary, and stirring as appropriate to dissolve or disperse the conjugated diene copolymer (A) in the liquid medium (B).

The binder composition for all-solid-state secondary batteries according to this embodiment can form a binder that exhibits high adhesion not only to the current collector of the electrode but also to the solid electrolyte material. Furthermore, since the binder composition for all-solid-state secondary batteries according to this embodiment can improve the conductivity of the solid electrolyte layer while reducing the amount used, it can be suitably used for all-solid-state batteries.

The method for preparing a binder composition for an all-solid-state secondary battery according to this embodiment may include a step of removing particulate metal components from the binder composition (hereinafter also referred to as the "particulate metal removal step"). In the particulate metal removal step, "particulate metal components" refers to those present in particulate form in the binder composition and does not include those present in a dissolved metal ion state.

The method for removing particulate metal components from the binder composition for all-solid-state secondary batteries in the particulate metal removal process is not particularly limited. Examples include removal by filtration using a filter, removal by vibrating sieve, removal by centrifugal separation, and removal by magnetic force. Among these, removal by magnetic force is preferred because the target of removal is metal components.

While the method of removal using magnetism is not particularly limited as long as it can remove the metal components, considering productivity and removal efficiency, a method of removing the components by placing a magnetic filter in the manufacturing line of the binder composition for all-solid-state secondary batteries and passing the polymer solution through it is preferred.

The step of removing particulate metal components from the polymer solution using a magnetic filter is preferably carried out by passing the solution through a magnetic filter that forms a magnetic field with a magnetic flux density of 100 gauss or more. Since a lower magnetic flux density reduces the efficiency of metal component removal, a magnetic flux density of 1000 gauss or more is preferable, more preferably 2000 gauss or more, and most preferably 5000 gauss or more, considering the removal of weakly magnetic stainless steel.

When placing magnetic filters in a manufacturing line, it is preferable to include a process upstream of the magnetic filter to remove coarse foreign matter or metal particles using a filter such as a cartridge filter. This is because coarse metal particles may pass through the magnetic filter depending on the filtration flow rate.

Furthermore, while a magnetic filter is effective even with a single filtration, a circulating system is preferable. This is because a circulating system improves the efficiency of removing metal particles.

When a magnetic filter is placed in the manufacturing line for a binder composition for all-solid-state secondary batteries, its placement is not particularly limited. However, it is preferable to place the magnetic filter immediately before filling the container with the binder composition for all-solid-state secondary batteries. If a filtration process using a filter exists before filling the container, it is preferable to place the magnetic filter before the filtration filter. This is to prevent contamination of the product if metal components detach from the magnetic filter.

Specific examples of particulate metal components include metals such as Fe, Ni, and Cr, or compounds thereof. In the binder composition for all-solid-state secondary batteries according to this embodiment, the above-mentioned particulate metal components may remain, but it is preferable to remove the particulate metal components in a particulate metal removal step so that the content of particulate metal components with a particle size of 20 μm or more is 10 ppm or less. The content of particulate metal components with a particle size of 20 μm or more can be determined by further filtering the obtained binder composition for all-solid-state secondary batteries with a mesh corresponding to a mesh opening of 20 μm, elemental analysis of the metal particles on the mesh using an X-ray microanalyzer (EPMA), and measurement of the metal dissolved in an acid capable of dissolving it using ICP (Inductively Coupled Plasma).

3. Slurry for All-Solid-State Secondary Battery A slurry for an all-solid-state secondary battery according to one embodiment of the present invention contains the above-described binder composition for all-solid-state secondary batteries and a solid electrolyte. The slurry for an all-solid-state secondary battery according to this embodiment can be used as a material for forming either the positive electrode active material layer or the negative electrode active material layer, or it can be used as a material for forming the solid electrolyte layer.

The slurry for forming the positive electrode active material layer of an all-solid-state secondary battery contains the above-mentioned binder composition for all-solid-state secondary batteries, a solid electrolyte, and an active material for the positive electrode (hereinafter also referred to as "positive electrode active material"). Similarly, the slurry for forming the negative electrode active material layer of an all-solid-state secondary battery contains the above-mentioned binder composition for all-solid-state secondary batteries, a solid electrolyte, and an active material for the negative electrode (hereinafter also referred to as "negative electrode active material"). Furthermore, the slurry for forming the solid electrolyte layer of an all-solid-state secondary battery contains the above-mentioned binder composition for all-solid-state secondary batteries and a solid electrolyte. The components that may be included in the slurry for all-solid-state secondary batteries according to this embodiment will be described below.

3.1. Active material <positive electrode active material>
Examples of positive electrode active materials include MnO ₂ , MoO ₃ , V ₂ O ₅ , V ₆ O ₁₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , Li _(1-x) CoO ₂ , Li _(1-x) NiO ₂ , Li _x Co _y Sn _z O ₂ , Li _(1-x) Co _(1-y) Ni _y O ₂ , Li _(1+x) Ni _1/3 Co _1/3 Mn _1/3 O ₂ , TiS ₂ , TiS ₃ , MoS ₃ , FeS ₂ , CuF ₂ , NiF Inorganic compounds of _{the second} class; carbon materials such as carbon fluoride, graphite, vapor-grown carbon fibers and/or their pulverized products, PAN-based carbon fibers and/or their pulverized products, pitch-based carbon fibers and/or their pulverized products; conductive polymers such as polyacetylene and poly-p-phenylene can be used. These positive electrode active materials may be used individually or in combination of two or more types.

The average particle size of the positive electrode active material is not particularly limited, but it is preferably 0.1 μm to 50 μm because it increases the contact area of the solid-solid interface. To obtain the desired average particle size of the positive electrode active material, grinders such as mortars, ball mills, sand mills, vibrating ball mills, satellite ball mills, and swirling airflow jet mills, or classifiers such as sieves and wind classifiers may be used. During grinding, wet grinding with water or a solvent such as methanol may be performed as needed. Classification can be performed using either dry or wet methods. Furthermore, the positive electrode active material obtained by the calcination method may be used after washing with water, acidic aqueous solution, alkaline aqueous solution, or organic solvent.

The average particle size of the active material refers to the volume-average particle diameter measured using a particle size distribution analyzer that employs laser diffraction as its measurement principle. Examples of such laser diffraction particle size distribution analyzers include the HORIBALA-300 series and the HORIBALA-920 series (both manufactured by Horiba, Ltd.).

In a slurry for all-solid-state secondary batteries used to form a positive electrode active material layer, the content of the positive electrode active material is preferably 20 to 90 parts by mass, and more preferably 40 to 80 parts by mass, when the total amount of solid components is 100 parts by mass.

<Negative electrode active material>
The negative electrode active material is not particularly limited as long as it can reversibly intercept and release lithium ions, etc., but examples include carbonaceous materials, metal oxides such as tin oxide and silicon oxide, lithium alloys such as elemental lithium and lithium aluminum alloy, and metals that can form alloys with lithium such as Sn, Si, or In. Among these, carbonaceous materials are preferred in terms of reliability, and silicon-containing materials are preferred in terms of being able to increase battery capacity.

Carbonaceous materials are not particularly limited as long as they are substantially composed of carbon, but examples include petroleum pitch, natural graphite, artificial graphite such as vapor-grown graphite, and carbonaceous materials obtained by firing various synthetic resins such as PAN-based resins and furfuryl alcohol resins. Furthermore, examples include various carbon fibers such as PAN-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA-based carbon fibers, lignin-based carbon fibers, glassy carbon fibers, and activated carbon fibers, as well as mesophase microspheres, graphite whiskers, and plate-shaped graphite.

Silicon-containing materials can absorb more lithium ions than commonly used graphite or acetylene black. This means that the amount of lithium ions absorbed per unit weight increases, allowing for a larger battery capacity. As a result, it offers the advantage of longer battery life, and its use in automotive batteries and other applications is expected in the future. On the other hand, silicon-containing materials are known to exhibit significant volume changes due to lithium ion absorption and release. While graphite and acetylene black experience volume expansion of approximately 1.2 to 1.5 times due to lithium ion absorption, silicon-containing negative electrode active materials can experience expansion of up to approximately 3 times. Repeated expansion and contraction (charging and discharging) can lead to insufficient durability of the negative electrode active material layer, potentially causing issues such as poor contact or a shortened cycle life (battery life). The negative electrode active material layer formed using the all-solid-state secondary battery slurry according to this embodiment exhibits high durability (strength) even with repeated expansion and contraction because the binder component follows the changes, resulting in excellent cycle life characteristics.

The average particle size of the negative electrode active material is not particularly limited, but it is preferably between 0.1 μm and 60 μm, as this increases the contact area of the solid-solid interface. To obtain the desired average particle size of the negative electrode active material, the pulverizers and classifiers exemplified above can be used.

In a slurry for all-solid-state secondary batteries used to form the negative electrode active material layer, the content of the negative electrode active material is preferably 20 to 90 parts by mass, and more preferably 40 to 80 parts by mass, when the total amount of solid components is 100 parts by mass.

3.2. Solid Electrolyte The slurry for the all-solid-state secondary battery according to this embodiment contains a solid electrolyte. As the solid electrolyte, any solid electrolyte commonly used in all-solid-state secondary batteries can be appropriately selected and used, but a sulfide-based solid electrolyte or an oxide-based solid electrolyte is preferred.

The lower limit of the average particle size of the solid electrolyte is preferably 0.01 μm, and more preferably 0.1 μm. The upper limit of the average particle size of the solid electrolyte is preferably 100 μm, and more preferably 50 μm.

In the slurry for all-solid-state secondary batteries according to this embodiment, the lower limit of the solid electrolyte content is preferably 50 parts by mass, more preferably 70 parts by mass, and particularly preferably 90 parts by mass, when the total amount of solid components is 100 parts by mass, in order to achieve both battery performance and the effect of reducing and maintaining interfacial resistance. The upper limit of the solid electrolyte content is preferably 99.9 parts by mass, more preferably 99.5 parts by mass, and particularly preferably 99.0 parts by mass, when the total amount of solid components is 100 parts by mass, for a similar effect. However, when used together with the positive electrode active material or the negative electrode active material, it is preferable that the sum of them falls within the above concentration range.

<Sulfide solid electrolyte>
Sulfide-based solid electrolytes are preferably those that contain a sulfur atom (S) and a metal element of Group 1 or Group 2 of the periodic table, and that are ionic conductive and electronically insulating. Examples of such sulfide-based solid electrolytes include sulfide-based solid electrolytes with compositional formulas represented by the following general formula (6).
Li _a M _b P _c S _d ...(6)
(In formula (6), M represents an element selected from B, Zn, Si, Cu, Ga, and Ge. a to d represent the composition ratio of each element, satisfying a:b:c:d = 1 to 12:0 to 1:1:2 to 9.)

In the above general formula (6), the composition ratio of Li, M, P, and S is preferably b = 0. More preferably, b = 0 and a:c:d = 1 to 9:1:3 to 7. Even more preferably, b = 0 and a:c:d = 1.5 to 4:1:3.25 to 4.5. The composition ratio of each element can be controlled by adjusting the amount of raw material compounds used when producing sulfide-based solid electrolytes.

The sulfide-based solid electrolyte may be amorphous (glass), crystalline (glass ceramic), or partially crystalline.

In Li-P-S based glass and Li-P-S based glass ceramics, the ratio of _Li₂S to _P₂S₅ is preferably 65:35 to 85:15, and more preferably 68:32 to 80:20, in terms of the molar ratio of _{Li₂S to P₂S₅} . By setting the ratio of _Li₂S to _P₂S₅ within _this range, the lithium ion conductivity can be increased. The lithium ion conductivity of the sulfide-based solid electrolyte is preferably 1 × ^10⁻⁴ S/ _cm or higher, and more preferably 1 × ^10⁻³ S/cm or higher.

Examples of such compounds include those derived from a raw material composition containing _Li₂S and sulfides of elements from groups 13 to 15. Specific examples include Li ₂ S-P ₂ S ₅ , Li ₂ S-GeS ₂ , Li ₂ S-GeS ₂ -ZnS, Li ₂ S-Ga ₂ S ₃ , Li ₂ S-GeS ₂ -Ga ₂ S ₃ , Li ₂ S-GeS ₂ -P ₂ S _{5 , Li2S} -GeS2 _{-Sb2S5 , Li2S} - _{GeS2 - Al2S3} , _Li2S - _SiS2 , _Li2S - _Al2S3 , _Li2S - _{SiS2 - Al2S3} , _{Li2S -} SiS ₂ -P ₂ S ₅ , Li ₂ S-SiS Examples include ₂ -LiI, _Li2S - _{SiS2-Li4SiO4 , Li2S} -SiS2- _Li3PO4 , _{and Li10GeP2S12} . Among these, crystalline and _/ or _{amorphous raw material compositions consisting of Li2S-P2S5, Li2S-GeS2-Ga2S3, Li2S-GeS2-P2S5 , Li2S - SiS2 - P2S5 , Li2S - SiS2 - Li4SiO4 , and Li2S - SiS2 - Li3PO4 are preferred because} they have high lithium _ion conductivity.

One method for synthesizing sulfide-based solid electrolytes using such raw material compositions is the amorphous process. Examples of amorphous processes include mechanical milling and quenching. Among these, the mechanical milling method is preferred because it allows processing at room temperature and simplifies the manufacturing process.

For example, see T. Ohtomo, A. Hayashi, M. Tatsumisago, Y. Tsuchida, S. Hama, K. Kawamoto, Journal of Power Sources, 233, (2013), pp231-235.
Alternatively, it can be synthesized by referring to literature such as A. Hayashi, S. Hama, H. Morimoto, M. Tatsumisago, T. Minami, Chem. Lett., (2001), pp. 872-873.

<Oxide-based solid electrolyte>
The oxide-based solid electrolyte preferably contains an oxygen atom (O) and a metal element from Group 1 or Group 2 of the periodic table, and is ionic conductive and electronically insulating. Examples of such oxide-based solid electrolytes include Li _xa La _ya TiO ₃ [xa = 0.3 to 0.7, ya = 0.3 to 0.7] (LLT), Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ), Li _3.5 Zn _0.25 GeO ₄ having a LISICON (Lithium Super Ionic Conductor) type crystal structure, LiTi ₂ P ₃ O ₁₂ having a NASICON (Natrium Super Ionic Conductor) type crystal structure, Li _{(1 + xb + yb)} (Al,Ga) _xb (Ti,Ge) _(2-xb) Si _yb P _(3-yb) O ₁₂ (where 0 ≤ xb ≤ 1, 0 ≤ yb ≤ 1), and Li ₇ La ₃ having a garnet type crystal structure. _Zr₂O₁₂ is _one example.

Furthermore, phosphorus compounds containing Li, P, and O are also preferred as oxide-based solid electrolytes. Examples include lithium phosphate ( _Li₃PO₄ ), LiPON and LiPOD (where D represents _at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au), in which some of the oxygen atoms of lithium phosphate are replaced with nitrogen atoms. LiAON (where A represents at least one selected from Si, B, Ge, Al, C, and Ga) can also be preferably used.

Among these, Li _{(1 + xb + yb)} (Al, Ga) _xb (Ti, Ge) _{(2 - xb)} Si _yb P _{(3 - yb)} O ₁₂ (where 0 ≤ xb ≤ 1 and 0 ≤ yb ≤ 1) is preferred because it has high lithium ion conductivity, is chemically stable, and is easy to handle. These may be used individually or in combination of two or more.

The lithium ion conductivity of the oxide-based solid electrolyte is preferably 1 × ^10⁻⁶ S/cm or higher, more preferably 1 × ^10⁻⁵ S/cm or higher, and particularly preferably 5 × ^10⁻⁵ S/cm or higher.

3.3 Other Additives The slurry for the all-solid-state secondary battery according to this embodiment may contain other additives as needed, in addition to the components described above. Examples of other additives include conductive additives, thickeners, and liquid media (excluding those introduced from the binder composition for the all-solid-state secondary battery).

<Conductive additive>
Conductive additives are added to the slurry for all-solid-state secondary batteries to form the positive electrode active material layer or the negative electrode active material layer, as they have the effect of assisting the conduction of electrons. Specific examples of conductive additives include activated carbon, acetylene black, Ketjen black, furnace black, graphite, carbon fiber, and carbon such as fullerene. Among these, acetylene black and furnace black are preferred. When the slurry for all-solid-state secondary batteries according to this embodiment contains a conductive additive, the content ratio of the conductive additive is preferably 20 parts by mass or less, more preferably 1 to 15 parts by mass, and particularly preferably 2 to 10 parts by mass, per 100 parts by mass of active material.

<Thickening agent>
Specific examples of thickeners include those exemplified in the section "Thickeners" under "2.2. Other Additives" above. When the slurry for all-solid-state secondary batteries according to this embodiment contains a thickener, the content ratio of the thickener is preferably 5 parts by mass or less, and more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the total solid content of the slurry for all-solid-state secondary batteries.

<Liquid media>
Specific examples of liquid media include the liquid media exemplified in section "2.1. Liquid Media (B)" above. When adding a liquid media to the slurry for all-solid-state secondary batteries according to this embodiment, the same liquid media as the liquid media (B) contained in the binder composition for all-solid-state secondary batteries may be added, or a different liquid media may be added, but it is preferable to add the same liquid media. The proportion of liquid media in the slurry for all-solid-state secondary batteries according to this embodiment can be adjusted to any proportion in order to improve its coatability and to suppress the concentration gradient of the conjugated diene copolymer (A) and active material during the drying process after coating.

3.4. Method for preparing slurry for all-solid-state secondary batteries The slurry for all-solid-state secondary batteries according to this embodiment may be manufactured by any method, as long as it contains the above-described binder composition for all-solid-state secondary batteries and a solid electrolyte.

To produce a slurry with better dispersibility and stability more efficiently and inexpensively, it is preferable to add a solid electrolyte and optional additives as needed to the above-mentioned binder composition for all-solid-state secondary batteries and mix them together. Mixing the binder composition for all-solid-state secondary batteries with the other components can be done by stirring using known methods.

For manufacturing slurries for all-solid-state secondary batteries, it is necessary to select a mixer capable of stirring the slurry to the extent that no aggregates of solid electrolyte particles remain, and to choose necessary and sufficient dispersion conditions. While the degree of dispersion can be measured by a particle gauge, it is preferable to mix and disperse the material so that aggregates larger than at least 100 μm are eliminated. Examples of mixers suitable for these conditions include ball mills, bead mills, sand mills, defoamers, pigment dispersers, grinders, ultrasonic dispersers, homogenizers, planetary mixers, and Hobart mixers.

The preparation of the slurry for all-solid-state secondary batteries (mixing of each component) is preferably carried out under reduced pressure for at least part of the process. This prevents the formation of air bubbles in the resulting positive electrode active material layer, negative electrode active material layer, or solid electrolyte layer. The degree of reduced pressure is preferably around 5.0 × ^10³ to 5.0 × ^10⁵ Pa in absolute pressure.

4. Solid Electrolyte Sheet A solid electrolyte sheet according to one embodiment of the present invention has a layer formed by coating and drying the above-mentioned slurry for all-solid-state secondary batteries on a substrate.

The solid electrolyte sheet according to this embodiment can be manufactured, for example, by applying the above-mentioned all-solid-state secondary battery slurry onto a base film using a blade method (e.g., doctor blade method), calendering method, spin coating method, dip coating method, inkjet method, offset method, die coating method, or spray method, drying to form a layer, and then peeling off the film. As such a film, a general-purpose film such as a release-treated PET film can be used.

Alternatively, a solid electrolyte sheet can be formed by directly applying and drying a slurry for all-solid-state secondary batteries containing a solid electrolyte onto the surface of the green sheet to which the solid electrolyte sheet is laminated, or onto the surface of other components of an all-solid-state secondary battery.

In this embodiment, it is preferable to coat the solid electrolyte sheet with the above-mentioned all-solid-state secondary battery slurry so that the layer thickness is preferably in the range of 1 to 500 μm, more preferably 1 to 100 μm. When the layer thickness is within this range, conductive ions such as lithium ions move more easily, resulting in higher battery output. Furthermore, when the layer thickness is within this range, the overall thickness of the battery can be reduced, thereby increasing the capacity per unit volume.

The drying method for the slurry of all-solid-state secondary batteries is not particularly limited, and any method such as heating drying, vacuum drying, or heating-vacuum drying can be used. The drying atmosphere is not particularly limited, and can be carried out, for example, under an atmospheric environment.

In the solid electrolyte sheet according to this embodiment, the polymer distribution coefficient of the solid electrolyte layer is preferably 0.60 to 1.00, more preferably 0.70 to 0.95, and even more preferably 0.75 to 0.90. The "polymer distribution coefficient" in this embodiment is a coefficient defined by the following measurement method.
(1) A solid electrolyte layer is formed on one side of the substrate using the method described above. This is then divided into two to create two solid electrolyte sheets, each having the same solid electrolyte layer.
(2) Attach double-sided tape (manufactured by Nichiban Co., Ltd., product number "NW-25") to the aluminum plate that has been prepared in advance, and then attach Kapton tape (manufactured by Teraoka Co., Ltd., product number "650S") on top of the double-sided tape with the adhesive side facing up.
(3) The solid electrolyte layer side of one of the solid electrolyte sheets prepared in (1) is attached to the adhesive side of the Kapton tape prepared in (2), and then pressed down with a roller.
(4) With the substrate facing upwards, fix the aluminum plate created in (3) to the horizontal surface, then pull the substrate upwards at a constant speed so that the angle with the aluminum plate is 90°, and peel the substrate away from the adhesive surface between the substrate and the solid electrolyte layer.
(5) Scrap off the solid electrolyte layer from both sides of the peeled interface, that is, the solid electrolyte layer remaining on the substrate up to a depth of 1.5 μm from the surface (or the entire remaining layer if less than 1.5 μm in thickness remains) and the solid electrolyte layer remaining on the adhesive tape up to a depth of 1.5 μm from the surface, and this will be designated as "Measurement Sample A".
(6) Scrap off the entire solid electrolyte layer from the other solid electrolyte sheet prepared in (1), and this will be designated as "measurement sample B".
(7) For each of the sample A and sample B, analysis is performed using pyrolysis gas chromatography with a high-frequency induction heating pyrolizer, and the polymer content (mass%) per unit weight of each sample is calculated. The polymer distribution coefficient is calculated by substituting the obtained values into the following formula (7).
Polymer distribution coefficient = (polymer content of sample A: mass%) / (polymer content of sample B: mass%) ..... (7)

According to equation (7) above, a polymer distribution coefficient of 1 indicates that the polymer components in the solid electrolyte layer are uniformly distributed. Furthermore, a polymer distribution coefficient greater than 1 indicates that the polymer components are unevenly distributed near the peeling interface between the substrate and the solid electrolyte layer, while a value less than 1 indicates that the polymer components near the peeling interface are sparsely distributed.

Therefore, when the polymer distribution coefficient of the solid electrolyte layer is 0.60 to 1.00, sufficient polymer components are present near the interface between the substrate and the solid electrolyte layer, resulting in good adhesion between the substrate and the solid electrolyte layer, and a solid electrolyte sheet for all-solid-state secondary batteries with excellent electrical properties can be obtained. If the polymer distribution coefficient of the solid electrolyte layer is below the above range, there are fewer polymer components that function as a binder at the interface between the substrate and the solid electrolyte layer, which tends to reduce the adhesion between the substrate and the solid electrolyte layer. In addition, such bleeding (migration) tends to impair the smoothness of the solid electrolyte layer surface. On the other hand, if the polymer distribution coefficient exceeds the above range, the binder components, which are insulators, become localized at the interface between the substrate and the solid electrolyte layer, which tends to increase the internal resistance of the solid electrolyte sheet and impair its electrical properties.

If the solid electrolyte sheet contains both a positive electrode active material and a solid electrolyte, the solid electrolyte sheet functions as a positive electrode active material layer. If the solid electrolyte sheet contains both a negative electrode active material and a solid electrolyte, the solid electrolyte sheet functions as a negative electrode active material layer. Furthermore, if the solid electrolyte sheet does not contain positive or negative electrode active materials but contains a solid electrolyte, the solid electrolyte sheet functions as a solid electrolyte layer.

5. Electrodes for All-Solid-State Secondary Batteries and All-Solid-State Secondary Batteries An electrode for an all-solid-state secondary battery according to one embodiment of the present invention comprises a current collector and an active material layer formed by applying and drying the above-mentioned slurry for all-solid-state secondary batteries on the surface of the current collector. Such an electrode for an all-solid-state secondary battery can be manufactured by applying the above-mentioned slurry for all-solid-state secondary batteries to the surface of a current collector such as metal foil to form a coating film, and then drying the coating film to form an active material layer. The electrode for an all-solid-state secondary battery manufactured in this manner has an active material layer containing the above-mentioned conjugated diene copolymer (A), solid electrolyte, and active material, as well as optional components added as needed, bonded to the current collector, and therefore exhibits excellent flexibility, abrasion resistance, and powder shedding resistance, as well as good charge-discharge durability characteristics.

For the positive and negative electrode current collectors, it is preferable to use electron conductors that do not undergo chemical changes. For the positive electrode current collector, aluminum, stainless steel, nickel, titanium, and their alloys are preferred, as are aluminum or stainless steel treated with carbon, nickel, titanium, or silver on its surface. Among these, aluminum and aluminum alloys are more preferred. For the negative electrode current collector, aluminum, copper, stainless steel, nickel, titanium, and their alloys are preferred, with aluminum, copper, and copper alloys being more preferred.

While film sheets are typically used as the shape of the current collector, nets, punched materials, lath materials, porous materials, foams, and molded fiber bundles can also be used. The thickness of the current collector is not particularly limited, but 1 μm to 500 μm is preferred. Furthermore, it is preferable to create a textured surface on the current collector through surface treatment.

Methods for applying the slurry for all-solid-state secondary batteries onto the current collector include the doctor blade method, reverse roll method, comma bar method, gravure method, or air knife method. For drying the coated film of the all-solid-state secondary battery slurry, the processing temperature is preferably 20 to 250°C, more preferably 50 to 150°C, and the processing time is preferably 1 to 120 minutes, more preferably 5 to 60 minutes.

Alternatively, the active material layer formed on the current collector may be compressed by press processing. Suitable press processing methods include high-pressure super presses, soft calenders, and 1-ton presses. The press processing conditions can be appropriately set depending on the processing machine used.

The active material layer formed on the current collector in this manner has, for example, a thickness of 40 to 100 μm and a density of 1.3 to 2.0 g/ ^cm³ .

The electrodes for all-solid-state secondary batteries manufactured in this manner are suitably used as electrodes in an all-solid-state secondary battery, specifically as the positive and/or negative electrodes, which are configured in which a solid electrolyte layer is sandwiched between a pair of electrodes. Furthermore, the solid electrolyte layer formed using the above-described slurry for all-solid-state secondary batteries is suitably used as the solid electrolyte layer for all-solid-state secondary batteries.

The all-solid-state secondary battery according to this embodiment can be manufactured using known methods. Specifically, the following manufacturing methods can be used.

First, a slurry for the positive electrode of a solid-state secondary battery, containing a solid electrolyte and positive electrode active material, is applied to a current collector and dried to form a positive electrode active material layer, thereby creating a positive electrode for a solid-state secondary battery. Next, a slurry for the solid electrolyte of a solid-state secondary battery, containing a solid electrolyte, is applied to the surface of the positive electrode active material layer of the positive electrode and dried to form a solid electrolyte layer. Furthermore, a slurry for the negative electrode of a solid-state secondary battery, containing a solid electrolyte and negative electrode active material, is applied to the surface of the solid electrolyte layer and dried in the same manner to form a negative electrode active material layer. Finally, by placing a current collector (metal foil) on the negative electrode side on the surface of the negative electrode active material layer, the desired structure of a solid-state secondary battery can be obtained.

Furthermore, a solid electrolyte sheet can be fabricated on a release PET film and bonded to a pre-fabricated positive electrode or negative electrode for a solid-state secondary battery. The desired solid-state secondary battery structure can then be obtained by peeling off the release PET film. The application method for each of the above compositions may be a conventional method. In this case, it is preferable to perform heat treatment after the application of the slurry for the positive electrode of the solid-state secondary battery, the slurry for the solid electrolyte layer of the solid-state secondary battery, and the slurry for the negative electrode of the solid-state secondary battery. The heating temperature is preferably above the glass transition temperature of the conjugated diene copolymer (A). Specifically, 30°C or higher is preferred, 60°C or higher is more preferred, and 100°C or higher is most preferred. The upper limit is preferably 300°C or lower, and more preferably 250°C or lower. Heating within this temperature range softens the conjugated diene copolymer (A) while maintaining its shape. This allows for good adhesion and lithium-ion conductivity in the solid-state secondary battery.

Furthermore, it is also preferable to pressurize while heating. The pressurized pressure is preferably 5 kN/ ^cm² or higher, more preferably 10 kN/ ^cm² or higher, and particularly preferably 20 kN/ ^cm² or higher. In this specification, discharge capacity refers to the value per unit weight of the electrode's active material, and in the case of a half-cell, it refers to the value per unit weight of the negative electrode's active material.

6. Examples The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

6.1. Measurement Methods for Each Physical Property In the following examples and comparative examples, the measurement methods for each physical property are as follows.

(1) Measurement of 1,2-vinyl bond content The 1,2-vinyl bond content (unit: mol%) in the polymer was determined by ^1H -NMR at 500 MHz using deuterated chloroform as the solvent.

(2) Bound Styrene Content The bound styrene content (in %) in the polymer was determined by ^1H -NMR at 500 MHz using deuterated chloroform as the solvent.

(3) Weight-average molecular weight (Mw), number-average molecular weight (Mn), and Mw/Mn
The weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined from the retention time corresponding to the peak of the maximum peak of the GPC curve obtained using gel permeation chromatography (GPC) (product name "HLC-8120GPC", manufactured by Tosoh Corporation), and the Mw/Mn ratio was calculated.
(GPC conditions)
• Columns: Two "GMHXL" columns (manufactured by Tosoh Corporation) • Column temperature: 40°C
Mobile phase: Tetrahydrofuran; Flow rate: 1.0 mL/min; Sample concentration: 10 mg/20 mL

6.2. Manufacturing Examples of Denaturation Initiators [Manufacturing Example 1]
Two 4L stainless steel pressure vessels, vacuum-dried, were prepared. 985g of cyclohexane, 120g of the compound represented by formula (1-3) below, and 86g of tetramethylethylenediamine were added to the first pressure vessel to produce the first reaction solution. Simultaneously, 318g of 20% by weight liquid n-butyllithium and 874g of cyclohexane were added to the second pressure vessel to produce the second reaction solution. At this time, the molar ratio of the compound represented by formula (1-3), n-butyllithium, and tetramethylethylenediamine was 1:1:1. While maintaining the pressure in each pressure vessel at 7 bar, the first reaction solution was injected into the first continuous channel at an injection rate of 1.0 g/min, and the second reaction solution into the second continuous channel at an injection rate of 1.0 g/min, using a mass flow meter. During this time, the temperature of the continuous reactor was maintained at -10°C, the internal pressure was maintained at 3 bar using a back pressure regulator, and the residence time in the reactor was adjusted to be within 10 minutes. The reaction was terminated to obtain the denaturing initiator.

[Manufacturing Example 2]
Two 4L stainless steel pressure vessels, vacuum-dried, were prepared. In the first pressure vessel, 944g of cyclohexane, 161g of the compound represented by formula (1-1) below, and 86g of tetramethylethylenediamine were added to prepare the first reaction solution. Simultaneously, in the second pressure vessel, 318g of 20% by weight of liquid n-butyllithium and 874g of cyclohexane were added to prepare the second reaction solution. At this time, the molar ratio of the compound represented by formula (1-1), n-butyllithium, and tetramethylethylenediamine was 1:1:1. While maintaining the pressure in each pressure vessel at 7 bar, the first reaction solution was injected into the first continuous channel of the continuous reactor at an injection rate of 1.0 g/min, and the second reaction solution was injected into the second continuous channel at an injection rate of 1.0 g/min, using a mass flow meter. During this time, the temperature of the continuous reactor was maintained at -10°C, the internal pressure was maintained at 3 bar using a back pressure regulator, and the residence time in the reactor was adjusted to be within 10 minutes. The reaction was terminated to obtain the denaturing initiator.

[Manufacturing Example 3]
Two 4L stainless steel pressure vessels, vacuum-dried, were prepared. In the first pressure vessel, 898g of cyclohexane, 207g of the compound represented by formula (1-2) below, and 86g of tetramethylethylenediamine were added to prepare the first reaction solution. Simultaneously, in the second pressure vessel, 318g of 20% by weight of liquid n-butyllithium and 874g of cyclohexane were added to prepare the second reaction solution. At this time, the molar ratio of the compound represented by formula (1-2), n-butyllithium, and tetramethylethylenediamine was 1:1:1. While maintaining the pressure in each pressure vessel at 7 bar, the first reaction solution was injected into the first continuous channel of the continuous reactor at an injection rate of 1.0 g/min, and the second reaction solution was injected into the second continuous channel at an injection rate of 1.0 g/min, using a mass flow meter. During this time, the temperature of the continuous reactor was maintained at -10°C, the internal pressure was maintained at 3 bar using a back pressure regulator, and the residence time in the reactor was adjusted to be within 10 minutes. The reaction was terminated to obtain the denaturing initiator.

6.3. Synthesis Example of Conjugated Diene Copolymer (A) <Synthesis Example 1>
In the first reactor of a continuous reactor consisting of three reactors connected in series, 3.08 kg/h of styrene solution (60% by weight of styrene dissolved in n-hexane), 12.90 kg/h of 1,3-butadiene solution (60% by weight of 1,3-butadiene dissolved in n-hexane), 47.66 kg/h of n-hexane, 10 g/h of 1,2-butadiene solution (2.0% by weight of 1,2-butadiene dissolved in n-hexane), 10.0 g/h of a polar additive (10% by weight of 2,2-(di-2(tetrahydrofuryl)propane dissolved in n-hexane), and 292.50 g/h of the modification initiator produced in Production Example 1 were injected. At this time, the temperature of the first reactor was maintained at 50°C, and when the polymerization conversion rate reached 43%, the polymer was transferred from the first reactor to the second reactor via a transfer pipe.

Next, a 1,3-butadiene solution, in which 1,3-butadiene was dissolved in n-hexane at a rate of 60% by weight, was injected into the second reactor at a rate of 0.68 kg/h. During this time, the temperature of the second reactor was maintained at 65°C. When the polymerization conversion rate reached 95% or higher, the polymer was transferred from the second reactor to the third reactor via a transfer pipe.

The polymer was transferred from the second reactor to the third reactor, and a solution containing N,N-bis(3-(diethoxy(methyl)silyl)propyl)-methyl-1-amine was added to the third reactor as a denaturing agent [denaturing agent: act. Li = 1:1 mol]. The temperature of the third reactor was maintained at 65°C.

Subsequently, a solution of IR1520 (manufactured by BASF), dissolved at 30% by weight as an antioxidant, was injected into the polymerization solution discharged from the third reactor at a rate of 170 g/h and stirred. The resulting polymer was then placed in steam-heated hot water, stirred to remove the solvent, and a conjugated diene copolymer (A-1) was produced.

<Synthesis Example 2>
The procedure was carried out in the same manner as in Synthesis Example 1, except that a solution containing 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine) was continuously supplied to the third reactor as a denaturing agent instead of N,N-bis(3-(diethoxy(methyl)silyl)propyl)-methyl-1-amine, to produce a conjugated diene copolymer (A-2) [denaturing agent: aca. Li = 1:1 mol].

<Synthesis Example 3>
In Synthesis Example 1, the process was carried out in the same manner as in Example 1, except that the denaturing initiator produced in Production Example 2 was continuously supplied to the first reactor at a rate of 292.5 g/h instead of the denaturing initiator produced in Production Example 1, to produce a conjugated diene copolymer (A-3).

<Synthesis Example 4>
In Synthesis Example 1, the process was carried out in the same manner as in Synthesis Example 1, except that the denaturing initiator produced in Production Example 3 was continuously supplied to the first reactor at a rate of 292.5 g/h instead of the denaturing initiator produced in Production Example 1, to produce a conjugated diene copolymer (A-4).

<Synthesis Example 5>
In Synthesis Example 1, the procedure was carried out in the same manner as in Synthesis Example 1, except that a solution containing 3-(dimethoxy(methyl)silyl)-N,N-diethylpropane-1-amine was continuously supplied to the third reactor as a denaturing agent instead of N,N-bis(3-(diethoxy(methyl)silyl)propyl)-methyl-1-amine, to produce a conjugated diene copolymer (A-5) [denaturing agent: aca. Li = 1:1 mol].

<Synthesis Example 6>
In the first reactor of a continuous reactor consisting of three reactors connected in series, 6.58 kg/h of styrene solution (60% by weight of styrene dissolved in n-hexane), 9.58 kg/h of 1,3-butadiene solution (60% by weight of 1,3-butadiene dissolved in n-hexane), 47.66 kg/h of n-hexane, 10 g/h of 1,2-butadiene solution (2.0% by weight of 1,2-butadiene dissolved in n-hexane), 10.0 g/h of a polar additive (10% by weight of 2,2-(di-2(tetrahydrofuryl)propane dissolved in n-hexane), and 292.5 g/h of the denaturation initiator produced in Production Example 1 were injected. At this time, the temperature of the first reactor was maintained at 50°C, and when the polymerization conversion rate reached 43%, the polymer was transferred from the first reactor to the second reactor via a transfer pipe.

Next, a 1,3-butadiene solution, in which 1,3-butadiene was dissolved in n-hexane at a rate of 60% by weight, was injected into the second reactor at a rate of 0.50 kg/h. During this time, the temperature of the second reactor was maintained at 65°C. When the polymerization conversion rate reached 95% or higher, the polymer was transferred from the second reactor to the third reactor via a transfer pipe.

The polymer was transferred from the second reactor to the third reactor, and a solution containing N,N-bis(3-(diethoxy(methyl)silyl)propyl)-methyl-1-amine was added to the third reactor as a denaturing agent [denaturing agent: act. Li = 1:1 mol]. The temperature of the third reactor was maintained at 65°C.

Subsequently, a solution of IR1520 (manufactured by BASF), dissolved at 30% by weight as an antioxidant, was injected into the polymerization solution discharged from the third reactor at a rate of 167 g/h and stirred. The resulting polymer was then placed in steam-heated hot water, stirred to remove the solvent, and a conjugated diene copolymer (A-6) was produced.

<Synthesis Example 7>
In Synthesis Example 6, when the polymerization conversion rate reached 41%, the polymer was transferred from the first reactor to the second reactor via a transfer pipe, and a solution containing 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine) as a modifying agent was added to the third reactor [modifying agent: act. Li = 1:1 mol]. The procedure was carried out in the same manner as in Synthesis Example 6, except that a conjugated diene copolymer (A-7) was produced.

<Synthesis Example 8>
In Synthesis Example 1, the procedure was carried out in the same manner as in Synthesis Example 1, except that the solution containing N,N-bis(3-(diethoxy(methyl)silyl)propyl)-methyl-1-amine was not added to the third reactor, and a conjugated diene copolymer (A-8) was produced.

<Synthesis Example 9>
In the first reactor of a continuous reactor consisting of three reactors connected in series, the following were added: 3.08 kg/h of styrene solution (60% by weight of styrene dissolved in n-hexane), 12.90 kg/h of 1,3-butadiene solution (60% by weight of 1,3-butadiene dissolved in n-hexane), 47.66 kg/h of n-hexane, 10 g/h of 1,2-butadiene solution (2.0% by weight of 1,2-butadiene dissolved in n-hexane), and as a polar additive... A solution in which 2,2-(di-2(tetrahydrofuryl)propane was dissolved in n-hexane at a rate of 10.0 g/h was injected, and as a polymerization initiator, an n-butyllithium solution in which n-butyllithium was dissolved in n-hexane at a rate of 15% by weight was injected at a rate of 39.0 g/h. At this time, the temperature of the first reactor was maintained at 55°C, and when the polymerization conversion rate reached 48%, the polymer was transferred from the first reactor to the second reactor via a transfer pipe.

Next, a 1,3-butadiene solution, in which 1,3-butadiene was dissolved in n-hexane at a rate of 60% by weight, was injected into the second reactor at a rate of 0.68 kg/h. During this time, the temperature of the second reactor was maintained at 65°C. When the polymerization conversion rate reached 95% or higher, the polymer was transferred from the second reactor to the third reactor via a transfer pipe.

The polymer was transferred from the second reactor to the third reactor, and a solution containing dissolved dichlorodimethylsilane was added to the third reactor as a coupling agent [coupling agent: act. Li = 1:1 mol]. The temperature of the third reactor was maintained at 65°C.

Subsequently, a 30% by weight solution of IR1520 (manufactured by BASF) was added to the polymerization solution discharged from the third reactor at a rate of 170 g/h as an antioxidant, and the mixture was stirred. The resulting polymer was then placed in steam-heated hot water, stirred to remove the solvent, and a conjugated diene copolymer (A-9) was produced.

<Synthesis Example 10>
In the first reactor of a continuous reactor consisting of three reactors connected in series, 6.58 kg/h of styrene solution (60% by weight of styrene dissolved in n-hexane) and 9.58 kg/h of 1,3-butadiene solution (60% by weight of 1,3-butadiene dissolved in n-hexane) were administered.
At a rate of 47.66 kg/h, n-hexane, 10 g/h of a 1,2-butadiene solution (in which 1,2-butadiene is dissolved at 2.0 wt% in n-hexane), 10.0 g/h of a polar additive (in which 2,2-(di-2(tetrahydrofuryl)propane is dissolved at 10 wt% in n-hexane), and 39.0 g/h of an n-butyllithium solution (in which n-butyllithium is dissolved at 15 wt% in n-hexane) was injected as a polymerization initiator. During this time, the temperature of the first reactor was maintained at 55°C, and when the polymerization conversion rate reached 48%, the polymer was transferred from the first reactor to the second reactor via a transfer pipe.

Next, a 1,3-butadiene solution, in which 1,3-butadiene was dissolved in n-hexane at a rate of 60% by weight, was injected into the second reactor at a rate of 0.50 kg/h. During this time, the temperature of the second reactor was maintained at 65°C. When the polymerization conversion rate reached 95% or higher, the polymer was transferred from the second reactor to the third reactor via a transfer pipe.

The polymer was transferred from the second reactor to the third reactor, and a solution containing dissolved dichlorodimethylsilane was added to the third reactor as a coupling agent [coupling agent: act. Li = 1:1 mol]. The temperature of the third reactor was maintained at 65°C.

Subsequently, a solution of IR1520 (manufactured by BASF), dissolved at 30% by weight, was added to the polymerization solution discharged from the third reactor at a rate of 167 g/h as an antioxidant, and the mixture was stirred. The resulting polymer was then placed in steam-heated hot water, stirred to remove the solvent, and a conjugated diene copolymer (A-10) was produced.

<Synthesis Example 11>
In Synthesis Example 1, the procedure was carried out in the same manner as in Synthesis Example 1, except that an n-butyllithium solution in which n-butyllithium is dissolved at 15% by weight in n-hexane was continuously added to the first reactor at a rate of 39.0 g/h, instead of the denaturation initiator produced in Production Example 1. A conjugated diene copolymer (A-11) was produced.

6.4. Example 1
6.4.1. Preparation of Binder Composition for All-Solid-State Secondary Batteries The conjugated diene copolymer (A-1) obtained in Synthesis Example 1 above and Smirizer GM 500 ppm as an antioxidant were added to diisobutyl ketone, which is a liquid medium (B), and the mixture was stirred at 90°C for 3 hours to dissolve the conjugated diene copolymer (A-1) and the antioxidant in the diisobutyl ketone. Then, this solution was transferred to a three-necked flask, and while maintaining a reduced pressure of 100 Torr, a bubbling of dry nitrogen gas with a water vapor content of 25.0 mg/L or less was performed at 90°C for 4 hours to reduce the residual moisture content to 55 ppm, thereby preparing a binder composition for all-solid-state secondary batteries. Next, this binder composition was passed through a cartridge filter (Advantec Co., Ltd., all-fluororesin cartridge filter, product name "TCF-300-H5MF") having a filter membrane with an average pore size of 3.00 μm, and filled into a 1 L Clean Barrier® bottle (barrier container for ultra-high purity solvents) commercially available from Aicello Chemical Co., Ltd. The total solid content of this binder composition, when considered as 100% by mass, is 10.1%. This preparation was carried out in a dry room with a cleanliness class of ISO 14644-1 Class 7 and an indoor dew point of -40°C DP or lower.

6.4.2. Preparation and Evaluation of Slurries for All-Solid-State Secondary Batteries <Preparation of Slurry for the Positive Electrode of All-Solid-State Secondary Batteries>
A slurry for a positive electrode of an all-solid-state secondary battery was prepared by mixing 70 parts by mass of _LiCoO₂ (average particle size: 10 μm) as the positive electrode active material, 30 parts by _mass of sulfide glass consisting of _Li₂S and _P₂S₅ as the solid electrolyte ( _{Li₂S / P₂S₅} = 75 mol%/25 mol%, average particle size: 5 μm), 2 parts by mass of acetylene black as a conductive additive, and 2 parts by mass of the binder composition prepared above in terms of solid content. Diisobutyl ketone was then added to adjust the solid content concentration to 75%, and the mixture was then mixed for 10 minutes in a rotation-orbit mixer (THINKY Co., Ltd., Awatori Rentaro ARV-310) to prepare a slurry for a positive electrode of an all-solid-state secondary battery.

<Preparation of slurry for the solid electrolyte layer of all-solid-state secondary batteries>
_{A slurry for the solid electrolyte layer of an all-solid-state secondary battery was prepared by mixing 100 parts by mass of sulfide glass (Li₂S/P₂S₅ = 75 mol %} /25 mol%, average particle size 5 μm) consisting of _Li₂S and P₂S₅ as a solid electrolyte with 2 parts by mass of the binder composition prepared above in terms of solid content, and then adding diisobutyl ketone to adjust the solid content concentration to 55%, and then mixing for 10 minutes in a rotation-orbit mixer (THINKY Co., Ltd., Awatori Rentaro ARV-310).

<Preparation of slurry for negative electrode of all-solid-state secondary battery>
A slurry for the negative electrode of an all _- solid-state secondary battery was _{prepared by mixing 65 parts by mass of artificial graphite (average particle size: 20 μm) as the negative electrode active material, 35 parts by mass of sulfide glass consisting of Li₂S and P₂S₅ (Li₂S/P₂S₅ = 75 mol %} /25 mol%, average particle size: 5 μm) as the solid electrolyte, and 2 parts by mass of the binder composition prepared above in terms of solid content. Diisobutyl ketone was then added to adjust the solid content concentration to 65%, and the mixture was then mixed for 10 minutes in a rotation-orbit mixer (THINKY Co., Ltd., Awatori Rentaro ARV-310).

<Evaluation of dispersion stability of slurry>
The slurry for the solid electrolyte layer of the all-solid-state secondary battery obtained above was measured for viscosity at 25°C using a 50 rpm B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) within 5 minutes of preparation, and this viscosity was set to _η0 . This slurry for the solid electrolyte layer of the all-solid-state secondary battery was stored for 48 hours in a constant temperature bath maintained at 25°C, and the viscosity of the stored slurry was measured again at 25°C using a 50 rpm B-type viscometer (manufactured by Toki Sangyo Co., Ltd.), and this viscosity was set to _η1 . The viscosity change rate Δη (%) = ( _η1 / _η0 ) × 100 was calculated and evaluated according to the following criteria. The results are shown in Table 1 below. A smaller viscosity change rate Δη indicates better dispersion stability of the slurry.
(Evaluation criteria)
AA: Δη is between 80% and 120%.
A: Δη is 70% or more but less than 80%, or 120% or more but less than 130%.
B: Δη is 60% or more but less than 70%, or 130% or more but less than 140%.
C: Δη is less than 60% or 140% or more.

6.4.3. Fabrication and Evaluation of Positive and Negative Electrodes and Solid Electrolyte Layers of All-Solid-State Secondary Batteries <Fabrication of Positive Electrode of All-Solid-State Secondary Batteries>
The slurry for the positive electrode of a solid-state secondary battery prepared as described above was applied to aluminum foil using the doctor blade method, and the diisobutyl ketone was evaporated under reduced pressure at 120°C and dried for 3 hours to produce a positive electrode positive electrode with a positive electrode active material layer with a thickness of 0.1 mm.

<Preparation of the solid electrolyte layer>
The slurry for the solid electrolyte of the all-solid-state secondary battery prepared above was applied onto a release PET film using the doctor blade method, and a solid electrolyte layer with a thickness of 0.1 mm was fabricated by evaporating the diisobutyl ketone under reduced pressure at 120°C and drying for 3 hours.

<Fabrication of a negative electrode for all-solid-state secondary batteries>
The slurry for the negative electrode of a solid-state secondary battery prepared as described above was applied to a stainless steel foil using the doctor blade method, and the diisobutyl ketone was evaporated under reduced pressure at 120°C and dried for 3 hours to produce a negative electrode negative electrode with a thickness of 0.1 mm.

<Peel Strength Test of All-Solid-State Rechargeable Battery Cathode>
For the positive electrode active material layer formed on the aluminum foil of the positive electrode of the all-solid-state secondary battery obtained above, the peel strength was measured when a 20 mm wide tape was applied to the positive electrode active material layer and peeled off under conditions of a peel angle of 90° and a peel speed of 50 mm/min. The evaluation criteria are as follows. The results are shown in Table 1 below.
(Evaluation criteria)
AA: Peel strength of 20 N/m or more.
A: Peel strength is 10 N/m or more and less than 20 N/m.
B: Peel strength of 5 N/m or more and less than 10 N/m.
C: Peel strength is less than 5 N/m.

<Polymer distribution coefficient of the cathode of an all-solid-state secondary battery>
For the positive electrode active material layer formed on the aluminum foil of the positive electrode of the all-solid-state secondary battery obtained above, the polymer distribution coefficient in the thickness direction of the positive electrode active material layer was calculated as follows.
First, the obtained all-solid-state secondary battery positive electrode was divided into two. Next, a fixing stage was created by attaching 120 mm of double-sided tape (manufactured by Nichiban Co., Ltd., product number "NW-25") to a pre-prepared 70 mm x 150 mm aluminum plate, and then attaching Kapton tape (manufactured by Teraoka Co., Ltd., product number "650S") on top of the double-sided tape with the adhesive side facing up. On this fixing stage, the active material layer side of a test piece cut to a size of 20 mm x 100 mm from the obtained all-solid-state secondary battery positive electrode was attached and pressed down with a roller. The fixing stage with this test piece attached was placed on a horizontal surface, and the test piece was pulled up at a constant speed so that the angle with the fixing stage was 90°, and the current collector was peeled off from the adhesive surface. After that, the active material layer remaining on the current collector side to a depth of 1.5 μm from the surface and the active material layer remaining on the adhesive tape side to a depth of 1.5 μm from the surface were scraped off, and this was designated as measurement sample A. Meanwhile, the entire active material layer was scraped off from the other electrode that had been separated, and this was designated as sample B. Both sample A and sample B were analyzed using pyrolysis gas chromatography with a high-frequency induction heating pyrolizer, and the polymer content (mass%) per unit weight of each sample was calculated. The polymer distribution coefficient was calculated by substituting the obtained values into the following formula (7), and evaluated according to the following criteria. The results are shown in Table 1 below.
Polymer distribution coefficient = (polymer content of sample A: mass%) / (polymer content of sample B: mass%) ..... (7)
(Evaluation criteria)
AA: Polymer distribution coefficient is 0.85 or higher and less than 1.0.
A: Polymer distribution coefficient is 0.7 or higher and less than 0.85.
B: Polymer distribution coefficient is 0.55 or higher and less than 0.7.
C: Polymer distribution coefficient is less than 0.55.

<Flexibility Test of All-Solid-State Rechargeable Battery Cathode>
The aluminum foil side of the positive electrode test specimen was placed along a 1.0 mm diameter metal rod, and the specimen was wrapped around this rod to evaluate whether the positive electrode active material layer cracked and whether there was any damage to the wrapped end. The evaluation criteria are as follows. The results are shown in Table 1 below. Specimens that show no damage to the positive electrode active material layer indicate high flexibility of the specimen and good suitability for the all-solid-state secondary battery assembly process.
(Evaluation criteria)
A: No cracks in the positive electrode active material layer, and no damage to the winding ends.
B: No cracks in the positive electrode active material layer, but damage to the winding end.
C: Cracks present in the positive electrode active material layer.

<Measurement of lithium ion conductivity of the solid electrolyte layer>
The solid electrolyte layer, peeled from a PET film, was sandwiched between two stainless steel plates to form a cell. An impedance analyzer was used to measure the lithium-ion conductivity, and the Nyquist plot was used to calculate the lithium-ion conductivity. The evaluation criteria are as follows. The results are shown in Table 1 below. A higher lithium-ion conductivity indicates that a better-performing all-solid-state secondary battery can be obtained.
(Evaluation criteria)
AA: Lithium-ion conductivity of 0.8 × ^10⁻⁴ S/cm or more and 1.0 × ^10⁻⁴ S/cm or less.
A: Lithium-ion conductivity is 0.5 × ^10⁻⁴ S/cm or higher and less than 0.8 × ^10⁻⁴ S/cm.
B: Lithium-ion conductivity is 0.2 × ^10⁻⁴ S/cm or more and less than 0.5 × ^10⁻⁴ S/cm.
C: Lithium-ion conductivity is less than 0.2 × ^10⁻⁴ S/cm.

6.4.4. Fabrication and Evaluation of All-Solid-State Secondary Batteries <Fabrication of All-Solid-State Secondary Batteries>
The positive electrode of the all-solid-state secondary battery prepared as described above was cut into a disc shape with a diameter of 13 mm, and the negative electrode of the all-solid-state secondary battery and the solid electrolyte layer peeled from the PET film were cut into a disc shape with a diameter of 15 mm. Next, the positive electrode of the all-solid-state secondary battery was bonded to one side of the solid electrolyte layer so that the surface of the positive electrode active material layer of the positive electrode was in contact with the solid electrolyte layer. The negative electrode of the all-solid-state secondary battery was bonded to the other side of the solid electrolyte layer so that the surface of the negative electrode active material layer of the negative electrode was in contact with the solid electrolyte layer. Using a heat press machine, the materials were heated (120°C) and pressurized (600 MPa, 1 minute) to produce a laminate for the all-solid-state secondary battery having a laminated structure of aluminum foil/positive electrode active material layer/solid electrolyte layer/negative electrode active material layer/stainless steel foil. Next, the laminate for the all-solid-state secondary battery thus produced was placed in a stainless steel 2032 type coin case incorporating spacers and washers, and the 2032 type coin case was crimped to produce the all-solid-state secondary battery.

<Cycle life characteristics (capacity retention rate)>
Using the all-solid-state secondary battery prepared as described above, charge-discharge tests were conducted at 30°C. Charge and discharge measurements were performed at a rate of 0.1C within a potential range of 4.2V to 3.0V. This 0.1C rate charge-discharge was repeated, and when the discharge capacity after the first cycle was A (mAh/g) and the discharge capacity after the 20th cycle was B (mAh/g), the capacity retention rate after 20 cycles was calculated using the following formula (8). The evaluation criteria are as follows. The results are shown in Table 1 below.
Capacity retention rate after 20 cycles (%) = (B/A) × 100 ・・・・・(8)
In C-rate, C stands for time rate, and is defined as (1/X)C = rated capacity (Ah) / X (h). X represents the time it takes to charge or discharge electricity up to the rated capacity. For example, 0.1C means that the current value is rated capacity (Ah) / 10 (h).
(Evaluation criteria)
AA: Capacity retention rate is between 95% and 100%.
A: The capacity retention rate is between 90% and 95%.
B: Capacity retention rate is 85% or more but less than 90%.
C: Capacity retention rate is less than 85%.

6.5. Examples 2-8, Comparative Examples 1-3
Except for the types and amounts of components used as shown in Table 1 below, a binder composition for an all-solid-state secondary battery, a slurry for an all-solid-state secondary battery, positive and negative electrodes and solid electrolyte layers for an all-solid-state secondary battery, and an all-solid-state secondary battery were prepared and evaluated in the same manner as in Example 1 above.

Table 1 below summarizes the types of initiators and modifiers used in Examples 1-8 and Comparative Examples 1-3, their respective physical properties, and the evaluation results.

The abbreviations in Table 1 above represent the following compounds, respectively.
<Initiator>
Initiator a: Modified initiator synthesized in Production Example 1 Initiator b: Modified initiator synthesized in Production Example 2 Initiator c: Modified initiator synthesized in Production Example 3 Initiator d: n-butyllithium <modifier>
• Denaturing agent A: N,N-bis(3-(diethoxy(methyl)silyl)propyl)-methyl-1-amine • Denaturing agent B: 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine)
• Denaturing agent C: 3(dimethoxy(methyl)silyl)-N,N-diethylpropane-1-amine • Coupling agent D: Dichlorodimethylsilane

From the results in Table 1 above, it was confirmed that when using the binders for all-solid-state secondary batteries in Examples 1 to 8 and the binder compositions containing these binders, it is possible to produce all-solid-state secondary batteries with excellent lithium-ion conductivity and good cycle life characteristics.

Furthermore, in Examples 1 to 8, the slurry used for the all-solid-state secondary battery contained the binder composition for the all-solid-state secondary battery according to the present invention, along with an active material and a solid electrolyte. It was confirmed that this slurry exhibited better dispersion stability compared to Comparative Examples 1 to 3. In the active material layer formed by this slurry, during the measurement of peel strength, the active material layer itself did not become brittle, resulting in the detachment of the active material or solid electrolyte, or cracking. Sufficient bonding to the polymer was confirmed between both the active material and the solid electrolyte. It was also confirmed that it possessed good flexibility. This is presumed to be because the conjugated diene copolymer (A) contained in the binder compositions for the all-solid-state secondary battery in Examples 1 to 8 shown in Table 1 maintained high bonding strength, resulting in sufficient adhesion of the formed solid electrolyte to the active material layer.

The present invention is not limited to the embodiments described above, and various modifications are possible. The present invention encompasses configurations that are substantially identical to those described in the embodiments (for example, configurations with the same function, method, and result, or configurations with the same purpose and effect). The present invention also encompasses configurations in which non-essential parts of the configurations described in the embodiments are replaced with other configurations. Furthermore, the present invention also encompasses configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention also encompasses configurations that add known technology to the configurations described in the embodiments.

Claims (14)

It has aromatic vinyl units based on aromatic vinyl compounds and conjugated diene units based on conjugated diene compounds,
The compound, represented by the following general formula (1), contains a functional group derived from a denaturing initiator, which is a reaction product of an organometallic compound.
A binder for all-solid-state secondary batteries containing a conjugated diene copolymer (A).
(In formula (1) above, _R1 to _R3 are each independently hydrogen, a C1-C30 alkyl group, a C2-C30 alkenyl group, a C2-C30 alkynyl group, a C1-C30 heteroalkyl group, a C2-C30 heteroalkenyl group, a C2-C30 heteroalkynyl group, a C5-C30 cycloalkyl group, a C6-C30 aryl group, or a C3-C30 heterocyclic group. _R4 is a single bond, a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C5-C20 arylene group. Here, the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. ₅ is an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, a heteroalkyl group having 1 to 30 carbon atoms, a heteroalkenyl group having 2 to 30 carbon atoms, a heteroalkynyl group having 2 to 30 carbon atoms, a cycloalkyl group having 5 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heterocyclic group having 3 to 30 carbon atoms, or a functional group represented by the following general formula (1a) or general formula (1b). n is an integer from 1 to 5, and at least one of R ₅ is a functional group represented by the following general formula (1a) or general formula (1b). If n is an integer from 2 to 5, the multiple R _5s may be the same or different from each other.
(In the above general formula (1a), R ₆ is a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C6-C20 arylene group. Here, the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. _{R 7} and R ₈ are each independently a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group substituted with or unsubstituted C1-C20 alkylene group. ₉ is hydrogen, a C1-C30 alkyl group, a C2-C30 alkenyl group, a C2-C30 alkynyl group, a C1-C30 heteroalkyl group, a C2-C30 heteroalkenyl group, a C2-C30 heteroalkynyl group, a C5-C30 cycloalkyl group, a C6-C30 aryl group, or a C3-C30 heterocyclic group. X is an N, O, or S atom; if X is O or S, _R9 does not exist.
(In the above general formula (1b), R ₁₀ is a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C5-C20 cycloalkylene group, or a substituted or unsubstituted C6-C20 arylene group. Here, the substituents are C1-C10 alkyl groups, C5-C10 cycloalkyl groups, or C6-C20 aryl groups. _{R 11} and R ₁₂ are, independently, C1-C30 alkyl groups, C2-C30 alkenyl groups, C2-C30 alkynyl groups, C1-C30 heteroalkyl groups, C2-C30 heteroalkenyl groups, C2-C30 heteroalkynyl groups, C5-C30 cycloalkyl groups, C6-C30 aryl groups, or C3-C30 heterocyclic groups.) The binder for an all-solid-state secondary battery according to claim 1, wherein the conjugated diene copolymer (A) further comprises a functional group derived from a modifying agent represented by the following general formula (2) or the following general formula (3).
(In formula (2) above, R ₂₀ is a single bond or an alkylene group having 1 to 10 carbon atoms. _{R 21} and R ₂₂ are each independently an alkyl group having 1 to 10 carbon atoms. _{R 23} is a single bond or an alkylene group having 1 to 10 carbon atoms. _{R 24} is a divalent, trivalent, or tetravalent alkylsilyl group substituted with hydrogen, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms. a is an integer between 2 and 3. c is an integer between 1 and 3, b is an integer between 0 and 2, and b + c = 3.)
(In formula (3) above, _A1 and _A2 are each independently an alkylene group having 1 to 20 carbon atoms. _R25 to _R28 are each independently an alkyl group having 1 to 20 carbon atoms. _L1 to _L4 are each independently a divalent, trivalent, or tetravalent alkylsilyl group substituted with an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 20 carbon atoms.) The binder for an all-solid-state secondary battery according to claim 1, wherein the conjugated diene copolymer (A) has a bound styrene content of 5 to 50%. The binder for an all-solid-state secondary battery according to claim 1, wherein the content of functional groups in the conjugated diene copolymer (A) is 0.0005 mol/kg or more and 0.2 mol/kg or less. The binder for all-solid-state secondary batteries according to claim 1, wherein the ratio (Mw/Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the conjugated diene copolymer (A) is 3 or less. A binder for all-solid-state secondary batteries according to any one of claims 1 to 5, and a liquid medium (B) are included.
A binder composition for all-solid-state secondary batteries, wherein the liquid medium (B) is at least one selected from the group consisting of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ketones, esters, and ethers. The binder composition for an all-solid-state secondary battery according to claim 6, wherein the conjugated diene copolymer (A) is dissolved in the liquid medium (B). A slurry for an all-solid-state secondary battery, comprising the binder composition for an all-solid-state secondary battery described in claim 6 and a solid electrolyte. The slurry for an all-solid-state secondary battery according to claim 8, wherein the solid electrolyte contains a sulfide-based solid electrolyte or an oxide-based solid electrolyte. In an all-solid-state secondary battery comprising at least a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer,
An all-solid-state secondary battery in which at least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is a layer formed by applying and drying the slurry for all-solid-state secondary batteries described in claim 8. A solid electrolyte sheet for an all-solid-state secondary battery, having a layer formed by coating and drying the all-solid-state secondary battery slurry described in claim 8 on a substrate. In an all-solid-state secondary battery comprising at least a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer,
An all-solid-state secondary battery in which at least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is a layer formed from the solid electrolyte sheet for all-solid-state secondary batteries described in claim 11. A method for producing a solid electrolyte sheet for an all-solid-state secondary battery, comprising the steps of applying and drying the slurry for an all-solid-state secondary battery described in claim 8 onto a substrate. A method for manufacturing an all-solid-state secondary battery, comprising manufacturing an all-solid-state secondary battery via the method for manufacturing a solid electrolyte sheet for an all-solid-state secondary battery described in claim 13.