JP6123333B2 - Non-aqueous secondary battery negative electrode active material, negative electrode using the same, and non-aqueous secondary battery - Google Patents

Description

  The present invention relates to a nonaqueous secondary battery negative electrode active material, a nonaqueous secondary battery negative electrode formed using the active material, and a nonaqueous secondary battery including the negative electrode.

  In recent years, with the development of electric vehicles and the like, lithium ion secondary batteries, which are non-aqueous secondary batteries, have been actively studied as high energy density type batteries. For lithium ion secondary batteries, it is known to use a carbon material such as graphite as the negative electrode active material. Among them, graphite having a high degree of graphitization, when used as an active material for a negative electrode for a lithium ion secondary battery, has a capacity close to 372 mAh / g, which is the theoretical capacity for lithium occlusion of graphite. Since it is excellent also in the property, it is known that it is preferable as an active material for negative electrodes.

  When such a carbon material is used as an active material for a negative electrode of a lithium ion secondary battery, the surface of the carbon material is usually reacted with a polymer compound used as a binder or a non-aqueous electrolyte. A protective coating called SEI (Solid Electrolyte Interface) is formed. SEI prevents contact between the carbon material and the electrolyte, and suppresses decomposition of the electrolyte by the active carbon material. It is also known that the chemical stability of the negative electrode surface is maintained.

  However, in a lithium ion secondary battery using a carbon material as an active material for a negative electrode, the charge / discharge irreversible capacity during the initial cycle increases due to the generation of SEI film and the generation of gas as a side reaction product. There was a problem that the capacity could not be increased. In addition, the formation of a stable SEI film increases the interfacial resistance of the negative electrode, resulting in a decrease in input / output characteristics of the battery.

  In order to solve the above problem, a technique for coating a carbon material, which is a negative electrode active material, with a polymer or the like is known. Patent Document 1 discloses a non-aqueous lithium secondary battery in which a coating layer made of an ion conductive polymer or a water-soluble polymer is provided on the surface of a carbon material. According to Patent Document 1, a coating layer made of an ion conductive polymer such as polyethylene oxide or a water-soluble polymer such as polyvinyl alcohol (hydrolyzate of styrene-maleic anhydride copolymer) is formed of a non-aqueous electrolyte layer. It describes that it contributes to the improvement of the initial charge and discharge efficiency and the improvement of the cycle characteristics by fulfilling functions such as the suppression of decomposition or the suppression of the deposition of the decomposition products of the components of the nonaqueous electrolyte layer on the negative electrode surface. .

However, the polymers as described above have insufficient adhesion to the carbon material substrate, and initial discharge efficiency, cycle characteristics, and stability are still insufficient.
Therefore, amino groups have attracted attention as functional groups having good adhesiveness, and Patent Document 2 discloses a carbon material obtained by attaching an organic polymer having an aliphatic amino group in a side chain to a carbon material substrate. According to Patent Document 2, polyallylamine is most preferable as an organic polymer, and as an effect, irreversible capacity when used as an active material for a nonaqueous secondary battery negative electrode by adhering the organic polymer and modifying the surface is effective. It is described that can be reduced.

Patent Document 3 discloses an electrode material composed of a carbon material and an organic polymer having at least a tertiary nitrogen atom covering the carbon material in the main chain. In this document, polyethyleneimine is most preferable as an organic polymer, and as an effect, improvement in discharge characteristics is described by reducing the specific surface area of the carbon material.
Further, in Patent Document 4, at least a part of the surface is coated with a water-soluble polymer substance (polystyrene sulfonic acid in which polystyrene sulfonic acid or maleic acid is copolymerized) that is negatively charged in water in the production of the negative electrode. A non-aqueous secondary battery characterized by using a material containing carbon as an active material for a negative electrode and a non-aqueous electrolyte containing a compound reduced at a higher potential than propylene carbonate has been proposed. .

JP-A-11-129992 JP 2002-117851 A JP 2007-95494 A JP 2002-134171 A

  However, according to the study by the present inventors, the polymer disclosed in Patent Document 1 is an ion conductive polymer or a water-soluble polymer, and by coating such a polymer on a carbon material, an initial Although it is described that the charge / discharge efficiency and cycle characteristics are improved, the polymer is actually swollen by the electrolyte, and there is still room for improvement due to insufficient adhesion of the polymer film to the carbon material. It was a certain technology.

  On the other hand, Patent Document 2 discloses a carbon material in which a polymer having an amino group, which is a functional group having good adhesion to the surface of the carbon material, is attached to the carbon material. It has been found that when used as an active material, the initial charge / discharge efficiency is improved, but the interface resistance (negative electrode resistance) of the negative electrode tends to increase due to insufficient polymer ion conductivity. In the techniques described in Patent Documents 3 and 4, although the initial charge and discharge efficiency is somewhat improved as compared with the carbon material without any coating, the increase in the negative electrode resistance due to the coating and the reductive decomposition of the electrolyte cannot be sufficiently suppressed. Therefore, suppression of gas generation and sufficient improvement of cycle characteristics were not obtained.

  The present invention has been made in view of such background art, and in a non-aqueous secondary battery, the initial charge / discharge efficiency can be further improved while suppressing an increase in negative electrode resistance, and the capacity loss accompanying the charge / discharge cycle is also reduced. It is an object of the present invention to provide a reduced negative electrode material for a non-aqueous secondary battery.

  As a result of intensive studies to solve the above-described problems, the present inventors have found that an active material (A) capable of inserting / extracting lithium ions (hereinafter also referred to as “active material (A)”), In the active material for a non-aqueous secondary battery negative electrode containing the organic compound (B), by applying a compound different from the conventional one as the organic compound (B), initial charge / discharge is suppressed while suppressing an increase in negative electrode resistance. The present inventors have found that a non-aqueous secondary battery that can improve efficiency and gas generation suppression effect and has excellent cycle characteristics can be obtained, and the present invention has been completed.

Specifically, the organic compound (B) in the present invention is a compound that satisfies the condition that it has at least a π-conjugated structure and has a basic group.
Here, the details of the effect of the active material for a non-aqueous secondary battery negative electrode according to the present invention containing the organic compound (B) are unknown, but as a result of investigations by the inventors, excellent battery characteristics are as follows. It is thought that it is due to the effect.

That is, by including the organic compound (B) having the characteristics as described above and the active material (A), the π-conjugated structure of the organic compound (B) acts specifically on the surface of the active material (A). By doing so, there is an effect of suppressing the activity of the surface of the active material (A). In addition to the effect, high adsorptivity can be imparted between the surface of the active material (A) and the organic compound (B).
Moreover, the basic group which an organic compound (B) has acts on functional groups, such as a carboxyl group and an aldehyde group which exist in the surface of an active material (A), and an active material (A) and an organic compound (B) By improving the adsorptivity and suppressing peeling, there is an effect of suppressing cycle deterioration. Here, as an example, when the characteristic effect of the organic compound (B) on the carbon active material is given, since a π-conjugated structure exists on the basal plane which is the hexagonal network plane of the carbon active material, the organic compound (B) It is possible to adsorb specifically by the π-conjugated structure. In addition, since many functional groups exist on the edge surface, which is the end surface of the carbon active material, the basic group of the organic compound (B) works specifically and can be efficiently adsorbed to the carbon active material. . By such a function, reductive decomposition due to the reaction between the active material surface and the electrolytic solution is suppressed, and the initial charge / discharge efficiency can be improved.

The organic compound (B) has only to have at least a π-conjugated structure and a basic group for the reasons described above, and therefore the organic compound (B) may be a single compound. Two or more kinds of compounds may be mixed.
That is, the gist of the present invention is as follows.
<1> An active material for a negative electrode of a non-aqueous secondary battery containing an active material (A) capable of inserting and removing lithium ions and an organic compound (B), wherein the organic compound (B) is π-conjugated. It exists in the active material for nonaqueous secondary battery negative electrodes which has a structure and a basic group.
<2> The <1>, wherein the organic compound (B) is a mixture of an organic compound (X) having a π-conjugated structure and an organic compound (Y) having a basic group, and / or a reaction product thereof. It exists in the active material for non-aqueous secondary battery negative electrodes described in the above.
<3> The nonaqueous secondary battery according to <1> or <2>, wherein the π-conjugated structure is at least one selected from the group consisting of a benzene ring, a condensed aromatic ring, and an aromatic heterocycle. It exists in the active material for negative electrodes.
<4> Any of the above <1> to <3>, wherein the basic group is at least one selected from the group consisting of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group. It exists in the active material for non-aqueous secondary battery negative electrodes as described in any one.
<5> The organic compound (X) and / or the organic compound (Y) is an organic compound having a weight average molecular weight of 500 or more and 1,000,000 or less, according to any one of <1> to <4>. It exists in the active material for non-aqueous secondary battery negative electrodes.
<6> The non-aqueous secondary battery negative electrode active material according to any one of <1> to <5>, wherein the organic compound (B) further has an ion conductive group.
<7> The organic compound (B) is the non-aqueous secondary battery negative electrode active material according to <6> or <7>, including the following (1) and / or (2).
(1) A mixture of an organic compound (X) having a π-conjugated structure, an organic compound (Y) having a basic group, and an organic compound (Z) having an ion conductive group.
(2) At least two kinds of reaction products selected from the group consisting of an organic compound (X) having a π-conjugated structure, an organic compound (Y) having a basic group, and an organic compound (Z) having an ion conductive group .
<8> The ion conductive group of the organic compound (Z) is at least one selected from the group consisting of an oxyalkylene group, a sulfonyl group, boron, fluorine, a carboxyl group, a carbonyl group, a carbonate group, and a cyano group. The active material for a non-aqueous secondary battery negative electrode described in <7>.
<9> The organic compound (Z) is represented by the following general formula (1):

Wherein R ¹ and R ² are each independently a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, a glycidyl group or an epoxy group, and AO is an oxyalkylene group having 2 to 5 carbon atoms. And n is an integer from 1 to 50)
It exists in the active material for nonaqueous secondary battery negative electrodes as described in said <7> or <8> which is a compound represented by these.
<10> Any one of <7> to <9>, wherein the content of the organic compound (Z) in the active material with respect to the organic compound (Y) is 1% by mass or more and 300% by mass or less. It exists in the active material for non-aqueous secondary battery negative electrodes described in the above.

Another gist of the present invention includes a <11> current collector and an active material layer formed on the current collector, wherein the active material layer is any one of <1> to <10>. It exists in the negative electrode for non-aqueous secondary batteries containing the active material for non-aqueous secondary battery negative electrodes described in 1.
Another gist of the present invention is a nonaqueous secondary battery comprising a <12> positive electrode and a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for a nonaqueous secondary battery according to <11>. Exist.

  The non-aqueous secondary battery negative electrode active material according to the present invention, when used as a negative electrode material in a non-aqueous secondary battery, has an effect of suppressing initial charge / discharge efficiency and gas generation while suppressing an increase in negative electrode resistance. A nonaqueous secondary battery that can be improved and has excellent cycle characteristics can be provided.

Hereinafter, the contents of the present invention will be described in detail. In addition, the following description is an example of the embodiment of this invention, and this invention is not limited to these forms.
Here, “wt%” and “mass%” are synonymous, and “ppm” simply means “mass ppm”.
The non-aqueous secondary battery negative electrode active material of the present invention is a non-aqueous secondary battery negative electrode active material containing an active material (A) capable of inserting and removing lithium ions and an organic compound (B). The organic compound (B) has a π-conjugated structure and has a basic group.

<Active material (A)>
The active material (A) in the present invention is not particularly limited as long as it is a substance capable of occluding and releasing lithium ions, and examples thereof include graphite, amorphous carbon, a carbonaceous material having a low graphitization degree, and silicon. Graphite is preferred. Further, those coated with amorphous carbon or graphitized material may be used. These can be used alone or in combination of two or more.

  Graphite is easily available commercially, theoretically has a high charge / discharge capacity of 372 mAh / g, and further has a high current density compared to the case where other negative electrode active materials are used. This is preferable because the effect of improving the discharge characteristics can be expected greatly. Among them, graphite is preferably one having few impurities, and can be used after being subjected to various known purification treatments, if necessary. Examples of the type of graphite include natural graphite and artificial graphite, and natural graphite is more preferable.

  As artificial graphite, for example, coal tar pitch, coal heavy oil, atmospheric residue, petroleum heavy oil, aromatic hydrocarbon, nitrogen-containing cyclic compound, sulfur-containing cyclic compound, polyphenylene, polyvinyl chloride, polyvinyl Examples include those obtained by baking and graphitizing organic substances such as alcohol, polyacrylonitrile, polyvinyl butyral, natural polymer, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin. The firing temperature can be in the range of 2500 ° C. or more and 3200 ° C. or less, and a silicon-containing compound, a boron-containing compound, or the like can be used as a graphitization catalyst during firing.

  Examples of natural graphite include highly purified flaky graphite and spheroidized graphite. Among these, natural graphite subjected to spheroidizing treatment is more preferable from the viewpoint of particle filling properties and charge / discharge load characteristics. As an apparatus used for the spheronization treatment, for example, an apparatus that repeatedly gives mechanical effects such as compression, friction, shearing force, etc. including the interaction of graphite carbonaceous particles, mainly to impact force, to the particles can be used.

Specifically, it has a rotor with a large number of blades installed inside the casing, and when the rotor rotates at high speed, mechanical action such as impact compression, friction, shearing force, etc. is applied to the carbon material introduced inside. An apparatus that provides a surface treatment is preferable. Moreover, it is preferable to have a mechanism that repeatedly gives mechanical action by circulating graphite.
As a preferable apparatus for giving a mechanical action to the carbon material, for example, a hybridization system (manufactured by Nara Machinery Co., Ltd.), a kryptron (manufactured by Earth Technica), a CF mill (manufactured by Ube Industries), a mechano-fusion system (manufactured by Hosokawa Micron) ), Theta Composer (manufactured by Deoksugaku Kosakusha). Among these, a hybridization system manufactured by Nara Machinery Co., Ltd. is preferable.

When processing using the said apparatus, it is preferable that the peripheral speed of the rotating rotor is usually 30-100 m / sec, 40-100 m / sec, and more preferably 50-100 m / sec, for example. Further, the treatment that gives a mechanical action to the carbon material can be performed simply by passing graphite. However, it is preferable that the graphite is circulated or retained in the apparatus for 30 seconds or more, and is preferably treated for 1 minute or more in the apparatus. More preferably, the treatment is performed by circulation or retention.
Examples of the amorphous carbon include particles obtained by baking a bulk mesophase and particles obtained by infusibilizing and baking a carbon precursor.

  Examples of the carbonaceous material having a low graphitization degree include those obtained by firing an organic material at a temperature of usually less than 2500 ° C. Organic substances include coal-based heavy oil such as coal tar pitch and dry distillation liquefied oil; straight-run heavy oil such as atmospheric residual oil and vacuum residual oil; ethylene tar produced as a by-product during thermal decomposition of crude oil, naphtha, etc. Heavy oils such as cracked heavy oils; aromatic hydrocarbons such as acenaphthylene, decacyclene and anthracene; nitrogen-containing cyclic compounds such as phenazine and acridine; sulfur-containing cyclic compounds such as thiophene; and aliphatic cyclics such as adamantane Compounds: Polyphenylene such as biphenyl and terphenyl, polyvinyl esters such as polyvinyl chloride, polyvinyl acetate, and polyvinyl butyral, and thermoplastic polymers such as polyvinyl alcohol.

Depending on the degree of graphitization of the carbonaceous material, the firing temperature is usually 600 ° C. or higher, preferably 900 ° C. or higher, more preferably 950 ° C. or higher, usually less than 2500 ° C., preferably 2000 ° C. or lower, more preferably It is a range of 1400 ° C. or lower. At the time of baking, acids such as phosphoric acid, boric acid and hydrochloric acid, alkalis such as sodium hydroxide and the like can be mixed with the organic matter.
As the active material (A), particles obtained by coating the above natural graphite or artificial graphite with amorphous carbon and / or a graphite material having a low graphitization degree can also be used. Moreover, an oxide and other metals may be included. Other metals include metals that can be alloyed with Li, such as Sn, Si, Al, Bi.
The carbon material which comprises an active material (A) can also be used in combination with 1 type, or 2 or more types of another carbon material.

The active material (A) in the present invention preferably has the following physical properties.
The average particle diameter (d50) of the active material (A) is usually 1 μm or more and 50 μm or less. If it is within this range, it is possible to prevent inconveniences in processes such as striping when the negative electrode is produced, and on the other hand, the surface area is kept within an appropriate range, and the activity with the electrolyte solution can be prevented. Can be easily controlled. The average particle diameter (d50) is preferably 4 μm or more, more preferably 10 μm or more, and preferably 30 μm or less, more preferably 25 μm or less. In the present specification, the average particle diameter (d50) means a volume-based median diameter. Specifically, 0.01 g of a sample is suspended in 10 mL of a 0.2% by mass aqueous solution of polyoxyethylene sorbitan monolaurate, which is a surfactant, and introduced into a commercially available laser diffraction / scattering particle size distribution analyzer. After irradiating a 28 kHz ultrasonic wave with an output of 60 W for 1 minute, it can be obtained as a value measured as a volume-based median diameter in a measuring apparatus.

The specific surface area (BET specific surface area) measured by the BET method of the active material (A) of the present invention is usually 1 m ² / g or more and 11 m ² / g or less. If it is within this range, the part where lithium ions enter and exit is sufficient, good high-speed charge / discharge characteristics and output characteristics are obtained, the activity of the active material against the electrolyte is controlled, the initial irreversible capacity is reduced, and the capacity is increased. Can be easily achieved.
The BET specific surface area is preferably 1.2 m ² / g or more, more preferably 1.5 m ² / g.
In addition, it is preferably 10 m ² / g or less, more preferably 9 m ² / g or less, and still more preferably 8 m ² / g or less. In the specification of the present application, the BET specific surface area is a value measured by a BET 5-point method by a nitrogen gas adsorption flow method using a specific surface area measuring device.

When graphite is used as the active material (A) of the present invention, the (002) plane spacing d ₀₀₂ according to the X-ray wide angle diffraction method is usually 0.335 nm or more and less than 0.340 nm, preferably 0.339 nm or less. More preferably, it is 0.337 nm or less. When the d ₀₀₂ value is less than 0.340 nm, appropriate crystallinity can be obtained, and an increase in initial irreversible capacity can be suppressed. Note that 0.335 nm is a theoretical value of graphite.

<Organic compound (B)>
The organic compound (B) of the present invention is characterized by having at least a π-conjugated structure and a basic group, and further having an ion conductive group. 1) Electrolytic solution and solvent Promotes desolvation from hydrated lithium ions, reduces reductive decomposition of the electrolyte and improves initial charge / discharge efficiency, 2) promotes diffusion of lithium ions in the coating, Since an increase can be suppressed, it is preferable.

As long as the organic compound (B) of the present invention has at least a π-conjugated structure and a basic group, the organic compound (B) is a single compound, but two or more kinds of compounds are mixed. You may do it.
In the case of a single compound, the organic compound (B) is constituted by a single molecule having both a group having a π-conjugated structure and a basic group in the molecule, and preferably π It is constituted by a single molecule having a group having a conjugated structure, a basic group and an ion conductive group.

This single compound may be a compound having a π-conjugated structure (hereinafter sometimes referred to as organic compound (X)) and a compound having a basic group (hereinafter referred to as organic compound (Y)). )) (Hereinafter may be referred to as reaction product (XY)), preferably organic compound (X), organic compound (Y), and ionic conductivity. It is a reaction product (hereinafter sometimes referred to as a reaction product (XYZ)) with a compound having a group (hereinafter sometimes referred to as an organic compound (Z)).

The single compound described above may be a low molecular compound or a high molecular compound, but is preferably a high molecular compound (polymer) from the viewpoint of effectively suppressing gas generation. .
The weight average molecular weight when the organic compound (B) is a polymer compound is not particularly limited, but is usually 500 or more, preferably 1000 or more, more preferably 2000 or more, and further preferably 2500 or more. On the other hand, the weight average molecular weight is usually 1,000,000 or less, preferably 500,000 or less, more preferably 300,000 or less, and still more preferably 200,000 or less.

  In the present specification, the weight average molecular weight is a weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the solvent, or the solvent is aqueous or N, N-dimethylformamide. It is a weight average molecular weight in terms of standard polyethylene glycol measured by GPC of (DMF) or dimethyl sulfoxide (DMSO).

  When two or more kinds of compounds are mixed as the organic compound (B), the organic compound (B) is 1) a mixture containing the organic compound (X) and the organic compound (Y); 2) the organic compound ( X), mixture containing organic compound (Y) and organic compound (Z); 3) mixture containing reaction product (XY) and organic compound (Z); 4) organic compound (X) and organic compound (Z) reaction product (hereinafter sometimes referred to as reaction product (X-Z)) and organic compound (Y); 5) organic compound (Y) and organic compound (Z ) And a reaction product (hereinafter sometimes referred to as reaction product (YZ)) and organic compound (X); 6) reaction product (XZ) and reaction product Mixture containing (YZ); 7) Reaction product (XY) and reaction product (YZ) A mixture containing the reaction product (XY) and the reaction product (XZ); 9) a mixture containing the reaction product (XY) and the organic compound (X); 10) Mixture containing reaction product (XY) and organic compound (Y); 11) Mixture containing reaction product (XY), organic compound (X) and organic compound (Y); 12) In any one of the above 9) to 11), a configuration including a mixture further containing an organic compound (Z);

  In the specification of the present application, the mixture of the organic compound (X) and the organic compound (Y) includes the organic compound (X) and the organic compound (Y) in the non-aqueous secondary battery negative electrode active material. It is not always necessary to be mixed in the production process of the non-aqueous secondary battery negative electrode active material. Even when the mixture is used as the main organic compound (B), the organic compounds in the mixture may react with each other in producing the active material of the present invention. In that case, the content ratio of the mixture of the organic compound and the reaction product in the organic compound (B) is usually 50% with respect to the total amount of the organic compound (B) (content relative to the active material (A)). % By mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 99% by mass or more. The same applies when the organic compound (Z) and / or various reaction products are mixed.

  For example, when the reaction product (XY) of the organic compound (X) and the organic compound (Y) is used, the reaction product (XY) is added to the active material (A) as the organic compound (X) and the organic compound. After attaching (Y), a heating operation may be performed to react the organic compound (X) with the organic compound (Y). Alternatively, the organic compound (X) and the organic compound (Y) may be reacted to obtain a reaction product (XY), and then attached to the active material (A).

The former is preferred from the viewpoints of adhesion to the active material (A) and suppression of surface activity.
The form of the organic compound (B) is preferably composed of 1) a mixture containing the organic compound (X) and the organic compound (Y). 2) The organic compound (X), the organic compound (Y), and the organic It is more preferable that it is comprised from the mixture containing a compound (Z) from the reason which can ensure high adsorptivity to the active material surface, lithium ion conductivity, and productivity.

(1. π-conjugated structure)
The organic compound (B) of the present invention includes a π-conjugated structure. In this specification, a compound in which an organic compound has a π-conjugated structure is a structure in which π electrons are conjugated to form a resonance structure,
More specifically, an unsaturated cyclic compound having a structure in which atoms having π electrons are arranged in a ring, satisfying the Hückel rule, π electrons are delocalized on the ring, and the ring has a planar structure Define.

  As the π-conjugated structure, a benzene ring, a condensed aromatic ring and an aromatic heterocycle (hereinafter, collectively referred to as “aromatic ring”) are preferable from the viewpoint of the above-mentioned effects. Examples of such a ring structure include , Furan, pyrrole, imidazole, thiophene, phosphole, pyrazole, oxazole, isoxazole, thiazole, monocyclic 6-membered benzene, pyridine, pyrazine, pyrimidine, pyridazine, triazine, bicyclic Benzofuran, isobenzofuran, indole, isoindole, benzothiophene, benzophosphole, benzimidazole, purine, indazole, benzoxazole, benzoisoxazole, benzothiazole, bicyclic 6-membered ring +6 Member ring naphthalene, quinoline, isoquinolyl , Quinoxaline, quinazoline, cinnoline, anthracene polycyclic include rings having a skeleton of pyrene.

Among these, at least one selected from the group consisting of benzene, a condensed aromatic ring, and an aromatic heterocycle is preferable from the viewpoint of suppressing gas generation when a nonaqueous secondary battery is used. As the condensed aromatic ring, naphthalene is preferable.
By having such a structure, the organic compound (B) is adsorbed and / or bonded to the basal surface of the active material (A) to suppress the peeling of the film formed on the basal portion, resulting in a basal portion defect. It is considered that the reductive decomposition of the electrolyte solution in is reduced. As a result, the non-aqueous secondary battery obtained using the non-aqueous secondary battery negative electrode active material of the present invention has a reduced initial charge / discharge capacity loss and good initial charge / discharge efficiency. It is considered that gas generation due to side reaction with the aqueous electrolyte is also suppressed.

As a method for confirming the form in which the organic compound (B) is adsorbed and / or bonded to the π-conjugated structure portion of the non-aqueous secondary battery negative electrode active material, argon, nitrogen, hexane, toluene, 2, 2, 3 -Method of calculating the adsorption and / or binding amount of organic compound (B) by measuring various gas adsorption amounts such as trimethylbutane, field emission scanning electron microscope-energy dispersive X-ray (SEM-EDX) analysis, transmission And a method such as a scanning electron microscope-energy dispersive X-ray (TEM-EDX) analysis.

Hereinafter, the organic compound (X) having the π-conjugated structure will be described.
The organic compound (X) may be a low molecular compound or a high molecular compound as long as it has a π-conjugated structure. From the viewpoint of effectively suppressing gas generation, the high molecular compound (Polymer) is preferable.
In addition, since the resistance of the active material for the non-aqueous secondary battery negative electrode of the present invention to the electrolytic solution is improved, and the coating of the negative electrode active material (A) layer is difficult to elute into the electrolytic solution, the organic compound (X) is non-organic. What is hardly soluble in an aqueous electrolyte solution is more preferable. In addition, when it is immersed in a solvent in which the organic compound (X) is mixed in a volume ratio of 3: 7 with an organic compound (X) for 24 hours, it is the rate of decrease in dry weight before and after immersion. Means 10% by mass or less.

  The organic compound that is hardly soluble in the non-aqueous electrolyte preferably has an ionic group. The ionic group is a group capable of generating an anion or cation in water, and examples thereof include a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and salts thereof. Examples of the salt include lithium salt, sodium salt, potassium salt and the like. Among these, a sulfonic acid group and a lithium salt or a sodium salt thereof are preferable from the viewpoint of the initial irreversible capacity in the case of a non-aqueous secondary battery.

When the organic compound (X) is a low molecular compound, the organic compound (X) includes naphthalene sulfonic acid, lithium naphthalene sulfonate, sodium naphthalene sulfonate, benzene sulfonic acid, sodium benzene sulfonate, anthracene sulfonic acid, anthracene sulfone. Examples thereof include sodium acid, dimer, trimer and the like.
When the organic compound (X) is a polymer compound, the weight average molecular weight is not particularly limited, but is usually 500 or more, preferably 1000 or more, more preferably 2000 or more, and further preferably 2500 or more. On the other hand, the weight average molecular weight is usually 1,000,000 or less, preferably 500,000 or less, more preferably 300,000 or less, and still more preferably 200,000 or less.

When the organic compound (X) is a polymer compound (polymer), a polymer having an ionic group and an aromatic ring is preferable. Examples of the monomer from which the structural unit constituting the polymer is derived include a monomer having an ionic group and a monomer having an aromatic ring. Moreover, the monomer which has both an ionic group and an aromatic ring may be sufficient.
In this case, the polymer may be a copolymer of a monomer having an ionic group and not having an aromatic ring and a monomer having an aromatic ring and not having an ionic group. A polymer of monomers having both a functional group and an aromatic ring may be used. Further, it may be a mixture of a monomer polymer having an ionic group and a monomer polymer having an aromatic ring.

Among these, from the viewpoint of the stability of the organic compound (X) coated with the non-aqueous secondary battery negative electrode active material in the electrolyte, the organic compound (X) is a monomer having both an ionic group and an aromatic ring. A polymer is preferred.
The ionic group possessed by the monomer is the same as the ionic group in the organic compound (B) described above. Among them, a carboxylic acid group, a sulfonic acid group, or a salt thereof has stability and resistance in the battery. It is preferable from the viewpoint of suppression of increase.

Examples of monomers having an ionic group and an aromatic ring include styrene sulfonic acid, lithium styrene sulfonate, sodium styrene sulfonate, styrene aniline sulfonic acid, salts of styrene aniline sulfonic acid, vinyl benzoate and vinyl benzoate. Etc.
Furthermore, examples of the monomer having an ionic group and not having an aromatic ring include vinyl sulfonic acid, lithium vinyl sulfonate, sodium vinyl sulfonate, acrylic acid, sodium acrylate, lithium acrylate, etc., methacrylic acid Examples of the monomer having an aromatic ring and not having an ionic group include styrene, benzyl acrylate, and benzyl methacrylate.

  Specific examples of the polymer containing a structural unit derived from such a monomer include a styrene-vinyl sulfonic acid copolymer, a styrene-vinyl sulfonic acid sodium copolymer, a styrene-vinyl sulfonic acid lithium copolymer, and polystyrene. Sulfonic acid, lithium polystyrene sulfonate, sodium polystyrene sulfonate, polyaniline sulfonic acid, lithium polyaniline sulfonate, sodium polyaniline sulfonate, styrene-styrene sulfonate copolymer, styrene-lithium sulfonate lithium copolymer, styrene-styrene sulfone Acid sodium copolymer, polyvinyl benzoic acid, polyvinyl lithium benzoate, sodium polyvinyl benzoate, styrene-vinyl benzoic acid copolymer, styrene-vinyl lithium benzoate copolymer, Len - Sodium copolymer vinyl benzoate, and the like.

From the viewpoint of effectively suppressing gas generation, polystyrene sulfonic acid, polystyrene lithium sulfonate, sodium polystyrene sulfonate, styrene-styrene sulfonic acid copolymer, styrene-lithium sulfonic acid copolymer, styrene-styrene sulfonic acid Sodium copolymers, polyvinyl benzoic acid, lithium polyvinyl benzoate, sodium polyvinyl benzoate, styrene-vinyl benzoic acid copolymers, styrene-vinyl lithium benzoate copolymers and styrene-sodium vinyl vinyl copolymers are preferred.

Further, polystyrene sulfonic acid, lithium polystyrene sulfonate, sodium polystyrene sulfonate, styrene-lithium sulfonate lithium copolymer and styrene-sodium styrene sulfonate copolymer are more preferable, among which lithium polystyrene sulfonate, sodium polystyrene sulfonate, A styrene-lithium styrene sulfonate copolymer and a styrene-sodium styrene sulfonate copolymer are particularly preferred because of their high adsorptivity to the active material surface, particularly the graphite basal surface.
As the organic compound (X) described above, a commercially available one may be used, or it can be synthesized by a known method. In the present invention, the organic compound (X) can be used alone or in combination of two or more compounds, regardless of whether the compound is a low molecular compound or a high molecular compound.

(2. Basic group)
The basic group in the organic compound (B) of the present invention acts on the functional group on the surface of the active material (A) and suppresses the activity on the surface of the active material (A). Moreover, since the high adsorptivity between the surface of the active material (A) and the organic compound (B) is improved, the decomposition of the electrolytic solution is suppressed, and further excellent cycle characteristics are exhibited. .

The basic group in the organic compound (B) of the present invention is defined as a group that donates an electron pair, and is not particularly limited as long as it satisfies this definition. For example, a primary amino group Secondary amino group, tertiary amino group, and quaternary ammonium group.
Among these, a primary amino group, a secondary amino group, and a tertiary amino group are preferable, and a primary amino group and a secondary amino group are particularly preferable in terms of high adhesiveness or reactivity with the active material surface functional group.

The form in which the organic compound (B) is adsorbed and / or bonded to the edge surface of the carbonaceous material substrate can be confirmed by the method described above for the π-conjugated structure.
Hereinafter, an organic compound (Y) will be described as an example of a preferable organic compound having a basic group.
For example, what has a unit derived from an ethylenically unsaturated group containing amine as an organic compound (Y) is mentioned. Specifically, what has a unit represented by following formula (2) or (3) is mentioned.

(In the formula ^(2), R 3 ~R ⁵ are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, ^{R 6} is absent atom single bond or a 1 to 6 carbon atoms An alkylene group, and R ⁷ and R ⁸ are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.)

In (Equation ^{(3), R} 9 ~R ¹² are each independently hydrogen atom or an alkyl group having 1 to 6 carbon ^{atoms, R 13} and ^{R 14} are each independently, 1 to 6 carbon atoms R ¹⁵ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.)
The alkyl group having 1 to 6 carbon atoms in the formulas (2) and (3) may be linear or branched. For example, methyl, ethyl, propyl, isopropyl, butyl Group, isobutyl group, tert-butyl group, pentyl group, hexyl group, and the like, and a methyl group is preferable.

The alkylene group having 1 to 6 carbon atoms in the formulas (2) and (3) may be linear or branched, and examples thereof include a methylene group and an ethylene group, preferably methylene. It is a group.
In the formula (2), R ^{3 to} R ⁵ are each independently preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom, and R ⁶ is preferably a single bond or a methylene group in which no atom exists. R ⁷ and R ⁸ are each independently preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.

Among them, R ^{3 to} R ⁵ are all hydrogen atoms, R ⁶ is a single bond or a methylene group in which no atom is present, and R ⁷ and R ⁸ are hydrogen atoms, and the unit represented by the formula (2) Is more preferable. When R ⁷ and R ⁸ are hydrogen atoms and the organic compound (Y) has a primary amino group, it is preferable because of high adhesion or reactivity with the surface of the active material (A).
In the formula (3), R ^{9 to} R ¹² are each independently preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom, R ¹³ and R ¹⁴ are preferably a methylene group, ¹⁵ is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.

Among these, a unit represented by the formula (3), in which R ^{9 to} R ¹² are all hydrogen atoms, R ¹³ and R ¹⁴ are methylene groups, and R ¹⁵ is a hydrogen atom, is more preferable. In the case where R ¹⁵ is a hydrogen atom and the organic compound (Y) has a secondary amino group, it is preferable because of high adhesiveness or reactivity with the active material surface.
The organic compound (Y) should just contain either the unit of Formula (2) or the unit of Formula (3), and may contain both the unit of Formula (2) and Formula (3).

Furthermore, the organic compound (Y) may contain units other than the units of the formulas (2) and (3), and is derived from, for example, maleic acid, acrylamide, sulfur dioxide, vinyl sulfonic acid, or styrene. Units.
The organic compound (Y) may be a low molecular compound or a high molecular compound (polymer) as long as it has a basic group, but from the viewpoint of effectively suppressing gas generation, A polymer compound is preferred.

When the organic compound (Y) is a low molecular compound, a compound composed of vinylamine, allylamine or a derivative thereof is preferable.
Examples of vinylamine, allylamine and derivatives thereof include vinylamine, N-alkyl-substituted vinylamine (N-methylvinylamine etc.), N, N-dialkyl-substituted vinylamine (N, N-dimethylvinylamine etc.), divinylamine, N -Alkyl-substituted divinylamine (N-methyldivinylamine etc.), allylamine, N-alkyl-substituted allylamine (N-methylallylamine etc.), N, N-dialkyl-substituted allylamine (N, N-dimethylallylamine etc.), diallylamine, N- Examples thereof include alkyl-substituted diallylamine (N-methyldiallylamine and the like), dimers or trimers thereof.

The organic compound (Y) may be in the form of a salt such as acetate, hydrochloride, sulfate, amide sulfate, or ammonium salt. Further, the amine moiety may be modified such as partially ureated.
When the organic compound (Y) is a polymer compound, the weight average molecular weight is not particularly limited, but is usually 500 or more, preferably 1000 or more, more preferably 2000 or more, and further preferably 2500 or more. On the other hand, the weight average molecular weight is usually 1,000,000 or less, preferably 500,000 or less, more preferably 300,000 or less, and still more preferably 200,000 or less.

When the organic compound (Y) is a polymer compound, the organic compound (Y) is preferably at least one of an amine homopolymer and a copolymer containing an ethylenically unsaturated group. Specifically, it is preferably at least one of homopolymers and copolymers of vinylamine, allylamine or derivatives thereof.
When the organic compound (Y) is a polymer compound, as the organic compound (Y), any one of the above-mentioned vinylamine, allylamine or a homopolymer of any of their derivatives, any of the above-mentioned vinylamine, allylamine or their derivatives Any one or more of the above copolymers, or one or more of the above-mentioned vinylamine, allylamine or derivatives thereof and one or more copolymers of other components can be used.

Furthermore, maleic acid, acrylamide, sulfur dioxide, etc. may be used as other components. Examples of the copolymer containing other components include diallylamine-maleic acid copolymer.
From the viewpoint of the initial charge / discharge efficiency, preferably, vinylamine, allylamine, N-alkyl-substituted allylamine (N-methylallylamine, etc.), N, N-dialkyl-substituted allylamine (N, N-dimethylallylamine, etc.) or diallylamine homopolymer or copolymer More preferably, it is polyvinylamine, polyallylamine, poly-N-methylallylamine, poly-N, N-dimethylallylamine, polydiallylamine, polyN-methyldiallylamine, most preferably polyvinylamine or polyallylamine. .
In addition, in this invention, if an organic compound (Y) has a basic group, it can be used individually by 1 type or in combination of 2 or more types.

(3. Ion conductive group)
In the non-aqueous secondary battery manufactured using the non-aqueous secondary battery negative electrode active material of the present invention, the organic compound (B) further has an ion conductive group from the viewpoint of suppressing an increase in negative electrode resistance. Is preferred.

The ion conductive group in the present invention is defined as a group having a non-conjugated electron pair, and is not particularly limited to the following description, but includes an oxyalkylene group, a sulfonyl group, a sulfo group, It is preferably at least one selected from the group consisting of a boron functional group, a carbonyl group, a carbonate group, a phosphorus-containing functional group, an amide group, and an ester group. These ion-conducting groups can be expected to promote the effect of desolvation from the solvent for lithium ions solvated with the electrolyte, thereby reducing the reductive decomposition of the electrolyte and improving the initial charge / discharge efficiency. can do.

In addition, since the ion conductive group promotes the diffusion of lithium ions in the film of the active material (A) on which the film is formed, it is possible to suppress an increase in negative electrode resistance.
Hereinafter, the organic compound (Z) having an ion conductive group will be described.
The organic compound (Z) may be a low molecular compound or a high molecular compound as long as it has an ion conductive group. From the viewpoint of effectively suppressing gas generation, the organic compound (Z) may be a high molecular compound. A compound is preferred.

The organic compound (Z) can be used alone or in combination of two or more as long as it is an organic compound having an ion conductive group.
When the organic compound (Z) is a low molecular weight compound, ethylene glycol, diethylene glycol, triethylene glycol, succinic acid, succinic anhydride, sultone, taurine, monosaccharide, oligosaccharide, cyclodextrin, crown ether, benzenesulfonic acid and their Salts, naphthalenesulfonic acid and salts thereof, acetic acid and salts thereof, benzoic acid and salts thereof, amino acids and salts thereof, boric acid and salts thereof, lactic acid and salts thereof, dibutyl carbonate and the like. Among them, succinic acid, succinic anhydride, sultone, taurine, monosaccharide, oligosaccharide, cyclodextrin, benzenesulfonic acid and salts thereof, naphthalenesulfonic acid and salts thereof, acetic acid and Their salts, benzoic acid and their salts, amino acids and their salts, boric acid and their salts, dibutyl carbonate are preferred.

  The polymer compound which is a preferable embodiment when the organic compound (Z) in the present invention is a polymer compound is represented by the following formula (1).

(In the formula, R ¹ and R ² are each independently a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, a glycidyl group or an epoxy group. AO is an oxyalkylene group having 2 to 5 carbon atoms. And n is an integer from 1 to 50.)
In addition, a glycidyl group is a functional group represented by following formula (4), and an epoxy group is a functional group represented by following formula (5).

The alkyl group in the above formula (1) may be linear or branched, and examples thereof include an alkyl group having 1 to 20 carbon atoms, from the viewpoint of suppressing increase in negative electrode resistance. Preferably, it is a C1-C15 alkyl group, Most preferably, it is a C1-C10 alkyl group.
Examples of the aryl group in the above formula (1) include an unsubstituted or alkyl group-substituted phenyl group. From the viewpoint of easy availability of the material, the unsubstituted or alkyl group having 1 to 4 carbon atoms is preferable. And is particularly preferably an unsubstituted phenyl group.

Examples of the aralkyl group in the above formula (1) include an unsubstituted or alkyl-substituted benzyl group. From the viewpoint of easy availability of the material, an unsubstituted or alkyl group having 1 to 4 carbon atoms is preferable. And particularly preferably an unsubstituted benzyl group.
R ¹ and R ² in the above formula (1) are preferably a hydrogen atom, an alkyl group, an epoxy group, or a glycidyl group, more preferably an alkyl group, an epoxy group, or a glycidyl group from the viewpoint of initial charge / discharge efficiency. More preferred is a glycidyl group.

AO in the above formula (1) is an oxyalkylene group having 2 to 5 carbon atoms, and is preferably an oxyethylene group or an oxypropylene group from the viewpoint of suppressing an increase in negative electrode resistance.
As a preferable combination of R ¹ and R ² and AO, R ¹ and R ² are each independently a hydrogen atom, an alkyl group, an epoxy group, or a glycidyl group, and AO is an oxyalkylene group having 2 to 5 carbon atoms. Is preferred. More preferably, R ¹ and R ² are each independently an alkyl group, an epoxy group, or a glycidyl group, and AO is an oxyalkylene group having 2 to 5 carbon atoms. More preferably, R ¹ and R ² are each independently an alkyl group, an epoxy group, or a glycidyl group, and AO is an oxyethylene group or an oxypropylene group. Most preferably, R ¹ and R ² are both glycidyl groups, and AO is a combination of oxyethylene groups or oxypropylene groups.

In the above formula (1), n represents the number of oxyalkylene groups, and is preferably an integer of 1 to 25 from the viewpoint of suppressing increase in negative electrode resistance. When n is 2 or more, a plurality of oxyalkylene groups AO may be the same as or different from each other.
Specific examples of the organic compound (Z) include polyoxyethylene glycol diglycidyl ether, polyoxypropylene glycol diglycidyl ether, butoxypolyethylene glycol glycidyl ether, and the like.

The weight average molecular weight of the organic compound (Z) is not particularly limited, but is usually 50 or more, preferably 150 or more, more preferably 300 or more, and further preferably 350 or more. On the other hand, the weight average molecular weight is usually 1 million or less, preferably 500,000 or less, more preferably 10,000 or less, and still more preferably 5000 or less.
The composition ratio of the organic compound (Z) to the organic compound (Y) in the active material for a non-aqueous secondary battery negative electrode of the present invention is such that a sufficient amount of the organic compound (Y) acts on the active material (A), and From the point which can suppress a negative electrode resistance increase, it is 1 mass% or more and 300 mass% or less normally, Preferably it is 2 mass% or more and 150 mass% or less, More preferably, it is 3 mass% or more and 100 mass% or less, More preferably, they are 4 mass% or more and 50 mass% or less, Especially preferably, they are 5 mass% or more and 40 mass% or less.

<Method for producing active material for negative electrode of non-aqueous secondary battery>
The active material for a non-aqueous secondary battery negative electrode of the present invention is not particularly limited in the production method as long as it contains the active material (A) and the organic compound (B) described above as essential components. The organic compound (B) is preferably a mixture and / or reaction product of an organic compound (X) having at least a π-conjugated structure and an organic compound (Y) having a basic group, and further having an ion conductive group. The organic compound (Z) and other components may be mixed and / or reacted.

Further, in this specification, “containing the active material (A) and the organic compound (B)” means a state where the active material (A) and the organic compound (B) are mixed, on the surface of the active material (A). The state in which the organic compound (B) is adhered, the state in which the organic compound (B) is adhered in the pores of the active material (A), and the like are shown, and the state of the active material (A) and the organic compound (B) It does not depend on the relationship.
The state of the active material (A) and the organic compound (B) is, for example, a technique such as field emission scanning electron microscope-energy dispersive X-ray (SEM-EDX) analysis, X-ray photoelectron spectroscopy (XPS) analysis, etc. It can confirm by observing the particle | grain cross section of the active material for nonaqueous secondary battery negative electrodes using. These confirmation methods may be performed at the time when the non-aqueous secondary battery negative electrode active material is manufactured, or the negative electrode containing the non-aqueous secondary battery negative electrode active material according to the present invention, or the non-aqueous secondary battery May be performed on the manufactured product.

The active material for a nonaqueous secondary battery negative electrode according to the present invention can be produced, for example, by the following method.
The organic compound (X) and the organic compound (Y) are added to an organic solvent, water or a mixed solvent thereof, and the solution is mixed with the active material (A) and then dried by heating or / and reduced pressure. Thus, an active material for a non-aqueous secondary battery negative electrode containing the organic compound (B) in the active material (A) can be obtained. For example, the solution of the organic compound (X) and the solution of the organic compound (Y) may be prepared separately, or the solution is prepared by adding the organic compound (X) and the organic compound (Y) to the same solvent. May be prepared. From the viewpoint of the initial charge / discharge efficiency of the lithium ion secondary battery, it is preferable to separately prepare a solution of the organic compound (X) and a solution of the organic compound (Y).

  The solvent to be used is not particularly limited as long as the organic compound (X) and the organic compound (Y) are dissolved. Preferably, water, ethyl methyl ketone, toluene, acetone, methyl isobutyl ketone, ethanol, methanol, and the like can be given. It is done. Among these, water, ethyl methyl ketone, acetone, methyl isobutyl ketone, ethanol, and methanol are more preferable because of cost and ease of drying.

When a solution of the organic compound (X) and a solution of the organic compound (Y) are separately prepared, these solutions and the active material (A) may be mixed at the same time. The substance (A) may be mixed, or the active material (A) is mixed with either the organic compound (X) solution or the organic compound (Y) solution, and then the other solution is added to the obtained mixture. May be added.
Further, it is preferable to add a solution of the organic compound (X) and a solution of the organic compound (Y) when preparing the slurry in which the active material (A) is dispersed. This can also be achieved by improving the initial charge / discharge efficiency and suppressing gas generation by drying the organic compound (X) and the organic compound (Y) solvent after applying the negative electrode active material for the negative electrode to the negative electrode plate. This is because the manufacturing process can be simplified.

The slurry in which the active material (A) is dispersed is a step of applying the non-aqueous secondary battery negative electrode active material according to the present invention to the electrode surface for the negative electrode in order to produce a negative electrode for the non-aqueous secondary battery. Is one of the embodiments used in the above.
Among them, in terms of initial charge / discharge efficiency and gas generation suppression effect, after mixing the solution of the organic compound (X) or any solution of the organic compound (Y) with the active material (A), It is preferable to add a solution of

  Moreover, from the point which can coat the active material surface uniformly, after mixing the solution of organic compound (Y) and active material (A), what mixed or filtered the dried liquid and organic compound (X) are mixed. More preferably, after the organic compound (Y) solution, the organic compound (Z), and the active material (A) are mixed, the mixture is filtered or dried, and then the organic compound (X) is mixed. Particularly preferred.

The concentration of the organic compound (X) or the organic compound (Y) in the solvent when mixed with the active material (A) is usually 0.01% by mass or more and 70% by mass or less, respectively. If it is this range, it can be expected that the organic compound (X) and the organic compound (Y) are uniformly present on the surface of the active material (A) in the active material for the negative electrode of the non-aqueous secondary battery. Is obtained.
The concentration of the organic compound (X) or the organic compound (Y) in the solution is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and preferably 60% by mass or less. More preferably, it is 40 mass% or less.

  However, the above solution concentration is the concentration of the solution in contact with the active material (A), and the organic compound (X) solution and the organic compound (Y) solution are mixed simultaneously with the active material (A). Or when mixing these solutions with the active material (A), the concentration of the organic compound (B) is the sum of the organic compound (X) and the organic compound (Y). When adding the other solution after mixing either the solution of (X) or the solution of organic compound (Y) and the active material (A), each of the solution of organic compound (X) and the solution of organic compound (Y) Concentration.

Moreover, the addition amount of the organic compound (X) and the organic compound (Y) can be appropriately adjusted, and the blending amount is set so as to be a preferable content in the above-described active material for a non-aqueous secondary battery negative electrode of the present invention. It is preferable to adjust.
When drying with heating about the solution of organic compound (X) and / or organic compound (Y), temperature is 50 to 300 degreeC normally. Within this range, the drying efficiency is sufficient, battery performance deterioration due to the remaining solvent is avoided, the organic compound (X) and the organic compound (Y) are prevented from being decomposed, and the active material (A) and the organic compound. It is possible to easily prevent the effect from being reduced due to weak interaction with (X) and the organic compound (Y). The temperature is preferably 250 ° C. or lower, and preferably 100 ° C. or higher.

When drying the solution of the organic compound (X) and / or the organic compound (Y) under reduced pressure, the pressure is usually 0 MPa or less and −0.2 MPa or more in gauge pressure notation. If it is this range, it can dry comparatively efficiently. The pressure is preferably −0.03 MPa or less, and preferably −0.15 MPa or more.
Prior to drying, a solution containing the active material (A), the organic compound (X), and the organic compound (Y) may be filtered. Thereby, the removal effect of the organic compound (X) and the organic compound (Y) which are not attached to the active material (A) can be expected.

In addition, when the active material for a non-aqueous secondary battery negative electrode of the present invention contains other components such as the organic compound (Z), this is also similar to the organic compound (X) and the organic compound (Y). It adds to an organic solvent, water, or these mixed solvents, and is set as a solution, After mixing the active material (A), the solution is dried by heating or / and pressure reduction.
When other components such as the organic compound (Z) are added, a solution of the other components may be prepared separately from the solution of the organic compound (X) or the organic compound (Y), or these compounds May be added to the same solvent as the solution of the organic compound (X) or the organic compound (Y) to prepare a solution.

<Content of organic compound (B)>
The active material for a non-aqueous secondary battery negative electrode of the present invention is not particularly limited as long as it contains the active material (A) and the organic compound (B), but the content of the organic compound (B) is the active material ( It is 0.01 mass% or more and 10 mass% or less normally with respect to A). Within this range, the addition of the organic compound (B) can easily avoid the situation where the negative electrode resistance is increased and the charging rate is slowed or charging / discharging is impossible. The effect of reducing the specific surface area of the active material (A) due to the addition of (B) is sufficient, and good cycle characteristics and charging speed can be easily obtained.

The content of the organic compound (B) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and preferably 8% by mass or less, more preferably with respect to the active material (A). Is 5% by mass or less, more preferably 3% by mass or less, more preferably 1% by mass or less, particularly preferably 0.5% by mass or less, and most preferably 0.2% by mass or less.
When a mixture of the organic compound (X) and the organic compound (Y) is used as the organic compound (B), the content of the organic compound (X) is usually 0. It is 01 mass% or more and 10 mass% or less. Within this range, the addition of the organic compound (X) can easily avoid a situation in which the negative electrode resistance is increased and the charging rate is slowed or charging / discharging becomes impossible. The effect of reducing the specific surface area of the active material (A) by the addition of (X) is sufficient, and good cycle characteristics and charging speed can be easily obtained. The content of the organic compound (X) is preferably 0.06% by mass or more, more preferably 0.07% by mass or more, further preferably 0.08% by mass or more, particularly preferably 0.09% by mass or more, especially It is preferably 0.1% by mass or more, preferably 8% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, particularly preferably 2% by mass or less, and particularly preferably 1.5%. It is not more than mass%, most preferably not more than 1 mass%.

  Content of an organic compound (Y) is 0.01 mass% or more normally 10 mass% or less with respect to an active material (A). Within this range, the addition of the organic compound (Y) can easily avoid a situation in which the negative electrode resistance increases and the charging rate is slowed or charging / discharging becomes impossible. The effect of reducing the specific surface area of the active material (A) due to the addition of (Y) is sufficient, and good cycle characteristics and charging speed can be easily obtained. The content of the organic compound (Y) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, further preferably 0.12% by mass or more, and particularly preferably 0.14% by mass or more. Also, it is preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 1% by mass or less, particularly preferably 0.8% by mass or less, particularly preferably 0.5% by mass or less, and most preferably 0%. .3% by mass or less.

  Furthermore, when using an organic compound (Z), content of an organic compound (Z) is 0.005 mass% or more normally 10 mass% or less with respect to an active material (A). Within this range, the addition of the organic compound (Z) can easily avoid a situation in which the negative electrode resistance increases and the charging rate becomes slow or charging / discharging becomes impossible. The effect of reducing the specific surface area of the active material (A) due to the addition of (Z) is sufficient, and good cycle characteristics and charging speed can be easily obtained. The content of the organic compound (Z) is preferably 0.006% by mass or more, more preferably 0.007% by mass or more, further preferably 0.008% by mass or more, and particularly preferably 0.01% by mass or more. Also, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 1% by mass or less, particularly preferably 0.5% by mass or less, particularly preferably 0.3% by mass or less, and most preferably 0%. .1% by mass or less.

  When the solution containing the organic compound (B) is dried at the time of production, the content of the organic compound (B) can in principle be the amount of the organic compound (B) added at the time of production. When the organic compound (B) not attached to the active material (A) is removed, the weight loss of the obtained carbon material in the TG-DTA analysis, or the amount of the organic compound (B) contained in the filtrate Can be calculated.

The non-aqueous secondary battery negative electrode active material according to the present invention may contain any organic compound in addition to the organic compound (B). The type of the arbitrary organic compound is not particularly limited, but is preferably a polymer from the viewpoint that the adsorption to the active material (A) is stably maintained, and the mutual relationship with the organic compound (Y) having a basic group. Polyanionic organic compounds are particularly preferred in that the action is formed.
Although content of the said arbitrary organic compound is not specifically limited, 0.01 mass% or more and 10 mass% or less are preferable with respect to an active material (A).

<Physical properties of non-aqueous secondary battery negative electrode active material>
The active material for a non-aqueous secondary battery negative electrode of the present invention preferably has the following physical properties.
The average particle diameter (d50) of the active material for a nonaqueous secondary battery negative electrode of the present invention is usually 1 μm or more and 50 μm or less. Within this range, it is possible to prevent inconveniences in processes such as striping when the negative electrode is produced, and on the other hand, the surface area is kept within an appropriate range, and the electrolyte and The activity of can be easily controlled. The average particle diameter (d50) is preferably 3 μm or more, more preferably 5 μm or more, and preferably 30 μm or less, more preferably 25 μm or less.

The specific surface area measured by the BET method of the active material for a non-aqueous secondary battery negative electrode of the present invention is usually 1 m ² / g or more and 11 m ² / g or less. If it is within this range, the portion where Li enters and exits is sufficient, good high-speed charge / discharge characteristics and output characteristics are obtained, the activity of the active material with respect to the electrolyte is controlled, the initial irreversible capacity is reduced, and the capacity is increased. It can be easily achieved. The specific surface area is preferably 1.2 m ² / g or more, more preferably 1.5 m ² / g or more, and preferably 10 m.
² / g or less, more preferably ^9m 2 / g, more preferably not more than ^8m 2 / g. In the specification of the present application, the BET specific surface area is a value measured by a BET 5-point method by a nitrogen gas adsorption flow method using a specific surface area measuring device.

  The elution property of the organic compound (B) in the non-aqueous secondary battery negative electrode active material of the present invention is 5% of the non-aqueous secondary battery negative electrode active material at room temperature (25 ° C.) in a non-aqueous salt-free solvent. It can be evaluated by measuring the elution amount of the organic compound (B) into the solution when immersed for a period of time. The elution amount can be usually 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass, based on the total amount of the organic compound (B) contained in the non-aqueous secondary battery negative electrode active material. It is as follows. From the viewpoint of the strength of the electrode plate, it is particularly preferably 5% by mass or less.

  The non-aqueous solvent used in the elution evaluation can be appropriately selected from known non-aqueous solvents as the solvent for the non-aqueous electrolyte solution. For example, chain carbonates such as diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate; cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate; chain ethers such as 1,2-dimethoxyethane; tetrahydrofuran, 2-methyl Examples include cyclic ethers such as tetrahydrofuran, sulfolane, and 1,3-dioxolane; chain esters such as methyl formate, methyl acetate, and methyl propionate; and cyclic esters such as γ-butyrolactone and γ-valerolactone.

A non-aqueous solvent may be individual or may use 2 or more types together. In the case of a mixed solvent, a combination of a mixed solvent containing a cyclic carbonate and a chain carbonate is preferable, and the cyclic carbonate is more preferably ethylene carbonate.
As a method for quantifying the elution amount of the organic compound (B), after immersing the non-aqueous secondary battery negative electrode active material in the non-aqueous solvent component, the supernatant is recovered and dried to drive off the solvent, and the NMR or GPC 100 The method of calculating by the ratio of the peak intensity of the eluted component to the peak intensity in the case of% elution is mentioned.

<Negative electrode for non-aqueous secondary battery>
The present invention also relates to a negative electrode for a non-aqueous secondary battery formed using the active material for a negative electrode for a non-aqueous secondary battery according to the present invention. Examples of the negative electrode include a negative electrode for a lithium ion secondary battery. The method for producing the negative electrode for non-aqueous secondary battery and the selection of materials other than the non-aqueous secondary battery negative electrode active material of the present invention constituting the negative electrode for non-aqueous secondary battery are not particularly limited.

The negative electrode for a non-aqueous secondary battery of the present invention includes a current collector and an active material layer formed on the current collector, and the active material layer is at least an active for the negative electrode of the non-aqueous secondary battery of the present invention. It can contain a substance. The active material layer preferably further contains a binder.
The binder is not particularly limited, but a binder having an olefinically unsaturated bond in the molecule is preferable. Specific examples include styrene-butadiene rubber, styrene / isoprene / styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, and ethylene / propylene / diene copolymer. By using such a binder having an olefinically unsaturated bond, the swellability of the active material layer with respect to the electrolytic solution can be reduced. Of these, styrene-butadiene rubber is preferred because of its availability.

By using such a binder having an olefinically unsaturated bond in the molecule and the non-aqueous secondary battery negative electrode active material of the present invention in combination, the mechanical strength of the negative electrode plate can be increased. When the mechanical strength of the negative electrode plate is high, deterioration of the negative electrode due to charge / discharge is suppressed, and the cycle life can be extended.
The binder having an olefinically unsaturated bond in the molecule preferably has a high molecular weight and / or a high proportion of unsaturated bonds. As the molecular weight of the binder, the weight average molecular weight is usually 10,000 or more and 1,000,000 or less. If it is this range, both mechanical strength and flexibility can be controlled to a favorable range. The weight average molecular weight is preferably 50,000 or more, and preferably 300,000 or less.

As the ratio of olefinically unsaturated bonds in the binder molecule, the number of moles of olefinically unsaturated bonds per 1 g of the total binder can be usually 2.5 × 10 ⁻⁷ mol or more, and usually 5 × It can be 10 <^-6> mol or less. If it is this range, the intensity | strength improvement effect will be acquired sufficiently and flexibility will also be favorable. The number of moles is preferably 8 × 10 ⁻⁷ mol or more, and preferably 1 × 10 ⁻⁶ mol or less.

Moreover, about the binder which has an olefinically unsaturated bond, the unsaturation degree is 15 to 90% normally. The degree of unsaturation is preferably 20% or more, more preferably 40% or more, and preferably 80% or less. In the present specification, the degree of unsaturation represents the ratio (%) of the double bond to the repeating unit of the polymer.
As the binder, a binder having no olefinically unsaturated bond can also be used. By using a binder having no olefinically unsaturated bond in combination with a binder having an olefinically unsaturated bond in the molecule, an improvement in coating properties can be expected. When the binder having an olefinically unsaturated bond is 100% by mass, the mixing ratio of the binder having no olefinically unsaturated bond is usually 150% by mass or less in order to suppress a decrease in the strength of the active material layer. Preferably it is 120 mass% or less.

  Examples of binders having no olefinically unsaturated bond include thickening polysaccharides such as methylcellulose, carboxymethylcellulose, starch, carrageenan, pullulan, guar gum, xanthan gum (xanthan gum); polyethers such as polyethylene oxide and polypropylene oxide; Vinyl alcohols such as polyvinyl alcohol and polyvinyl butyral; polyacids such as polyacrylic acid and polymethacrylic acid or metal salts thereof; fluorine-containing polymers such as polyvinylidene fluoride; alkane polymers such as polyethylene and polypropylene; Examples include coalescence.

The active material layer may contain a conductive additive in order to improve the conductivity of the negative electrode. The conductive aid is not particularly limited, and examples thereof include carbon black such as acetylene black, ketjen black, and furnace black, fine powder made of Cu, Ni having an average particle size of 1 μm or less, or an alloy thereof. It is preferable that the addition amount of a conductive support agent is 10 mass% or less with respect to the active material for non-aqueous secondary battery negative electrodes of this invention.

The negative electrode for a non-aqueous secondary battery of the present invention is a slurry obtained by dispersing the active material for a non-aqueous secondary battery negative electrode of the present invention, and optionally a binder and / or a conductive auxiliary agent in a dispersion medium. It can be formed by coating and drying. As the dispersion medium, an organic solvent such as alcohol or water can be used.
It does not specifically limit as a collector which apply | coats a slurry, A well-known thing can be used. Specific examples include metal thin films such as rolled copper foil, electrolytic copper foil, and stainless steel foil. The thickness of the current collector is usually 4 μm or more and 30 μm or less. The thickness is preferably 6 μm or more, and preferably 20 μm or less.

The thickness of the non-aqueous secondary battery negative electrode active material layer (hereinafter sometimes simply referred to as “active material layer”) obtained by applying and drying the slurry is practical as a negative electrode and has a high-density current. From the point of sufficient lithium ion occlusion / release function with respect to the value, it is usually 5 μm or more and 200 μm or less. The thickness is preferably 20 μm or more, more preferably 30 μm or more, and preferably 100 μm or less, more preferably 75 μm or less.
You may adjust the thickness of an active material layer so that it may become the thickness of the said range by pressing after application | coating of a slurry and drying.

Although the density of the active material for the non-aqueous secondary battery negative electrode in the active material layer varies depending on the application, for example, in applications in which input / output characteristics such as in-vehicle applications and power tool applications are important, usually 1.10 g / cm ³ or more, 1.65 g / cm ³ or less. Within this range, it is possible to avoid an increase in contact resistance between particles due to the density being too low, and it is also possible to suppress a decrease in rate characteristics due to the density being too high. Density is preferably 1.20 g / cm ³ or more, more preferably 1.25 g / cm ³ or more. In applications where capacity is important, such as mobile devices such as mobile phones and personal computers, it is usually 1.45 g / cm ³ or more and 1.90 g /
cm ³ or less. If it is this range, the capacity | capacitance fall of the battery per unit volume by a density being too low can be avoided, On the other hand, the fall of the rate characteristic by a density being too high can also be suppressed. Density is preferably 1.55 g / cm ³ or more, more preferably 1.65 g / cm ³ or more, and particularly preferably 1.70 g / cm ³ or more.

<Non-aqueous secondary battery>
The basic configuration of the nonaqueous secondary battery according to the present invention can be the same as, for example, a known lithium ion secondary battery, and usually includes a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and an electrolyte. The negative electrode is a negative electrode for a non-aqueous secondary battery according to the present invention described above.

<Positive electrode>
The positive electrode can include a current collector and an active material layer formed on the current collector. The active material layer preferably contains a binder in addition to the positive electrode active material.
Examples of the positive electrode active material include metal chalcogen compounds that can occlude and release alkali metal cations such as lithium ions during charge and discharge. Of these, metal chalcogen compounds capable of inserting and extracting lithium ions are preferred.

Examples of metal chalcogen compounds include transition metal oxides such as vanadium oxide, molybdenum oxide, manganese oxide, chromium oxide, titanium oxide, and tungsten oxide; vanadium sulfide, molybdenum sulfide, titanium sulfide, CuS, and the like transition metal _sulfides; NIPS 3, phosphorus transition metals such as FEPS ₃ - sulfur _compounds; VSe 2, selenium compounds of transition metals such as _{NbSe 3; Fe 0.25 V 0.75 S} 2, Na 0.1 CrS Composite oxides of transition metals such as ₂ ; composite sulfides of transition metals such as LiCoS ₂ and LiNiS ₂ .

Among them, from the viewpoint of occlusion / release of lithium ions, V ₂ O ₅ , V ₅ O ₁₃ , VO ₂ , Cr ₂ O ₅ , MnO ₂ , TiO ₂ , MoV ₂ O ₈ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , TiS ₂ , V ₂ S ₅ , Cr _0.25 V _0.75 S ₂ , Cr _0.5 V _0.5 S _2, etc. are preferable, and LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and some of these transition metals are used as other metals. The lithium transition metal composite oxide substituted with is particularly preferable. These positive electrode active materials may be used alone or in combination.

  The binder for positive electrodes is not specifically limited, A well-known thing can be selected arbitrarily and can be used. Examples include inorganic compounds such as silicate and water glass, and resins having no unsaturated bond such as Teflon (registered trademark) and polyvinylidene fluoride. Among them, a resin having no unsaturated bond is preferable because it is difficult to decompose during the oxidation reaction. The weight average molecular weight of the binder can usually be 10,000 or more and 3 million or less. The weight average molecular weight is preferably 100,000 or more, and preferably 1,000,000 or less.

The positive electrode active material layer may contain a conductive additive in order to improve the conductivity of the positive electrode. The conductive aid is not particularly limited, and examples thereof include carbon powders such as acetylene black, carbon black, and graphite, various metal fibers, powders, and foils.
The positive electrode of the present invention is prepared by dispersing an active material, optionally a binder and / or a conductive auxiliary agent in a dispersion medium in the same manner as the above-described negative electrode manufacturing method, and applying this to a current collector. Can be formed. The current collector for the positive electrode is not particularly limited, and examples thereof include aluminum, nickel, and stainless steel (SUS).

<Electrolyte>
The electrolyte (sometimes referred to as “electrolyte”) is not particularly limited, and a non-aqueous electrolyte obtained by dissolving a lithium salt as an electrolyte in a non-aqueous solvent, or an organic polymer compound or the like is added to the non-aqueous electrolyte. By doing so, a gel-like, rubber-like, or solid sheet-like shape can be mentioned.
The non-aqueous solvent used for the non-aqueous electrolyte is not particularly limited, and a known non-aqueous solvent can be used. For example, chain carbonates such as diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate; cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain ethers such as 1,2-dimethoxyethane; tetrahydrofuran, 2-methyl Examples include cyclic ethers such as tetrahydrofuran, sulfolane, and 1,3-dioxolane; chain esters such as methyl formate, methyl acetate, and methyl propionate; and cyclic esters such as γ-butyrolactone and γ-valerolactone. A non-aqueous solvent may be individual or may use 2 or more types together. In the case of a mixed solvent, a combination of a mixed solvent containing a cyclic carbonate and a chain carbonate is preferable from the balance of conductivity and viscosity, and the cyclic carbonate is preferably ethylene carbonate.

The lithium salt used in the non-aqueous electrolyte is not particularly limited, and a known lithium salt can be used. For example, halides such as LiCl and LiBr; perhalogenates such as LiClO ₄ , LiBrO ₄ and LiClO ₄ ; inorganic lithium salts such as inorganic fluoride salts such as LiPF ₆ , LiBF ₄ and LiAsF ₆ ; LiCF ₃ SO ₃ , Examples include perfluoroalkane sulfonates such as LiC ₄ F ₉ SO ₃ ; fluorine-containing organic lithium salts such as perfluoroalkane sulfonic acid imide salts such as Li trifluoromethanesulfonyl imide ((CF ₃ SO ₂ ) ₂ NLi), and the like. . Of these, LiClO ₄ , LiPF ₆ , and LiBF ₄ are preferable.
A lithium salt may be used independently or may use 2 or more types together. The concentration of the lithium salt in the non-aqueous electrolyte can be in the range of 0.5 mol / L or more and 2.0 mol / L or less.

  When the organic polymer compound is included in the non-aqueous electrolyte solution described above and used in the form of a gel, rubber, or solid sheet, specific examples of the organic polymer compound include polyethylene oxide, polypropylene oxide, and the like. Polyether polymer compounds; Cross-linked polymers of polyether polymer compounds; Vinyl alcohol polymer compounds such as polyvinyl alcohol and polyvinyl butyral; Insolubilized vinyl alcohol polymer compounds; Polyepichlorohydrin; Polyphosphazene; Siloxane; Vinyl polymer compounds such as polyvinyl pyrrolidone, polyvinylidene carbonate, polyacrylonitrile; poly (ω-methoxyoligooxyethylene methacrylate), poly (ω-methoxyoligooxyethylene methacrylate-co-methyl methacrylate) And polymer copolymers such as poly (hexafluoropropylene-vinylidene fluoride).

The non-aqueous electrolyte solution described above may further contain a film forming agent.
Specific examples of the film forming agent include carbonate compounds such as vinylene carbonate, vinylethyl carbonate, and methylphenyl carbonate; alkene sulfides such as ethylene sulfide and propylene sulfide; and sultone compounds such as 1,3-propane sultone and 1,4-butane sultone. And acid anhydrides such as maleic acid anhydride and succinic acid anhydride.

Further, an overcharge inhibitor such as diphenyl ether or cyclohexylbenzene may be added to the non-aqueous electrolyte.
When using the above-mentioned various additives, the total content of the additives is the total amount of the non-aqueous electrolyte so as not to adversely affect other battery characteristics such as an increase in initial irreversible capacity, low temperature characteristics, and deterioration in rate characteristics. In general, it can be 10% by mass or less, in particular, 8% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

  Further, as the electrolyte, a polymer solid electrolyte which is a conductor of an alkali metal cation such as lithium ion can be used. Examples of the polymer solid electrolyte include a polymer in which a salt of Li is dissolved in the aforementioned polyether polymer compound, and a polymer in which the terminal hydroxyl group of the polyether is substituted with an alkoxide.

<Others>
In order to prevent a short circuit between the electrodes, a porous separator such as a porous membrane or a nonwoven fabric can usually be interposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte is impregnated into the porous separator. It is convenient to use it. As a material for the separator, polyolefin such as polyethylene and polypropylene, polyethersulfone, and the like are used, and polyolefin is preferable.

  The form of the non-aqueous secondary battery is not particularly limited. For example, a cylinder type in which a sheet electrode and a separator are spiraled; a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined; a coin type in which a pellet electrode and a separator are stacked Etc. Further, by storing batteries of these forms in an optional outer case, the battery can be used in an arbitrary shape and size such as a coin shape, a cylindrical shape, and a square shape.

  The procedure for assembling the non-aqueous secondary battery is not particularly limited, and can be assembled by an appropriate procedure according to the structure of the battery. For example, a negative electrode can be placed on an outer case, an electrolyte and a separator can be provided thereon, and a positive electrode can be placed so as to face the negative electrode, and can be caulked together with a gasket and a sealing plate to form a battery.

<Battery performance>
The non-aqueous secondary battery produced as described above exhibits the following performance.
About the non-aqueous secondary battery of this invention, initial stage charge / discharge efficiency can be normally made into 80% or more. If the initial charge / discharge efficiency is too low, there is a tendency to cause deterioration of cycle characteristics and gas generation. About the non-aqueous secondary battery of this invention, initial stage charge / discharge efficiency becomes like this. Preferably it is 85% or more, More preferably, it is 90% or more.
In the specification of the present application, the initial charge / discharge efficiency is obtained by calculating the respective charge capacity and discharge capacity from the energization amounts in the second, third, and fourth cycles in the charge / discharge program shown in Table 1 below. Calculated.

    Initial charge / discharge efficiency (%) = discharge capacity in the fourth cycle / (discharge capacity in the fourth cycle + capacity loss in the second, third, and fourth cycles (= charge capacity−discharge capacity)) × 100 (%)

In the table, “CC-CV charging” means charging after a certain amount of charge at a constant current until charging reaches a termination condition at a constant voltage. “CC discharge” means discharging at a constant current to the end condition.
About the non-aqueous secondary battery of this invention, capacity | capacitance loss can be normally 35.0 mAh / g or less. If the capacity loss is too large, the cycle characteristics tend to deteriorate. For the non-aqueous secondary battery of the present invention, the capacity loss is preferably 32.0 mAh / g or less, more preferably 31.5 mAh / g or less, more preferably 30.0 mAh / g or less, and most preferably 28.0 mAh / g. g or less.

In this specification, the capacity loss is obtained by calculating the charge capacity and discharge capacity from the energization amount at the first step of the second, third and fourth cycles in the charge / discharge program shown in the following table, and calculating from the following formula. It is.
Capacity loss (mAh / g) = second cycle (charge capacity-discharge capacity) + third cycle (charge capacity-discharge capacity) + fourth cycle (charge capacity-discharge capacity)
About the non-aqueous secondary battery of this invention, negative electrode resistance can be normally made into 24.5 or less. If the negative electrode resistance is too large, the charge / discharge rate tends to be slow. For the nonaqueous secondary battery of the present invention, the negative electrode resistance is preferably 20.0Ω or less, more preferably 15Ω or less, and most preferably 12Ω or less. In addition, although mentioned later, negative electrode resistance can be calculated | required based on a well-known method. Specifically, a coin cell battery is produced, a Cole-Cole plot is produced from the result of impedance measurement, and the diameter of an arc appearing in the plot can be read to obtain the interface resistance value.

Next, specific embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
The average particle size (d50) in the following is measured by laser diffraction / scattering particle size distribution measurement by suspending 0.01 g of a sample in 10 mL of a 0.2 mass% aqueous solution of polyoxyethylene sorbitan monolaurate as a surfactant. This is a value measured as a volume-based median diameter in a measuring apparatus after being introduced into an apparatus (trade name: LA-920 manufactured by HORIBA) and irradiated with an ultrasonic wave of 28 kHz for 1 minute at an output of 60 W.

<Example 1>
(1) Preparation of non-aqueous secondary battery negative electrode active material A 50 g of spheroidized natural graphite (average particle size (d50) 17 μm) was used as the active material (A), and the graphite and an aqueous solution as an organic compound (X) ( Aldrich lithium polystyrene sulfonate (weight average molecular weight: 75000, 30% aqueous solution) diluted to 0.8333 g with addition of 49.1667 g of distilled water and methyl ethyl ketone solution as organic compound (Y) (PAA- manufactured by Nittobo) 03-E (polyallylamine, weight average molecular weight 3000, 20% ethanol solution) 0.375 g diluted with 49.625 g of methyl ethyl ketone) and methyl ethyl ketone solution (made by NOF Corporation) as the organic compound (Z) Epiol E-400 (polyoxyethylene glycol diglycidyl ether, oxye And Ren radix 9) 0.025g to what has been diluted by the addition of methyl ethyl ketone 49.975g) was stirred into the flask. The composition ratio of the organic compound (Z) to the organic compound (Y) at this time was 33% by mass. The solvent was distilled off by heating to obtain a powdered non-aqueous secondary battery negative electrode active material A.
Next, a coin cell was produced according to the following procedure, and charge / discharge evaluation was performed.

(2) Slurry preparation 20 g of the non-aqueous secondary battery negative electrode active material A prepared above and 20.2 g of an aqueous solution of carboxymethyl cellulose (1% by mass) were mixed and mixed by a kneader (Awatori Kentaro, manufactured by Shinky Co., Ltd.). After kneading (kneading: 2000 rpm, 5 min; defoaming: 2200 rpm, 1 min), 0.5 g of styrene-butadiene rubber (SBR) -aqueous dispersion (40% by mass) is added, and kneading is performed again under the same conditions as above. Thus, an anode active material slurry A was prepared.

(3) Electrode plate preparation A copper foil (thickness: 18 μm) was placed on an Auto Film Applicator manufactured by Tester Sangyo Co., Ltd. and adsorbed by negative pressure. The slurry A was applied by placing an appropriate amount of the negative electrode active material slurry A in a copper foil shape and sweeping a film applicator (gap 255 μm) manufactured by Tester Sangyo at a speed of 10 mm / sec.

The copper foil coated with the negative electrode active material slurry A was dried in an inert oven (EPEC-75, manufactured by Isuzu Seisakusho Co., Ltd.) to obtain an electrode plate A ′ (90 ° C., 50 min, nitrogen flow 10 L /
min).
Thereafter, the electrode plate A ′ was passed through a press machine (3-ton mechanical precision roll press) to obtain an electrode plate A in which the active material layer was compressed. The portion of the copper foil coated with the negative electrode active material slurry is punched into a punch (φ =
12.5 mm, SNG, manufactured by Nogami Giken Co., Ltd.), weight measurement and film thickness measurement by a film thickness meter (IDS-112, manufactured by Mitutoyo Corporation) were performed, and basis weight and electrode plate density were calculated.

(4) Coin Cell Production The electrode plate A produced by the above method was punched into a disk shape having a diameter of 12.5 mm to form an electrode, and the lithium metal foil was punched into a disk shape having a diameter of 14 mm to form a counter electrode. A separator (made of a porous polyethylene film) impregnated with an electrolytic solution was placed between both electrodes, and a 2016 coin-type battery (coin cell) using the electrolytic solution was produced. As the electrolytic solution, a solution obtained by dissolving LiPF ₆ in a mixed solution of ethylene carbonate / dimethyl carbonate / ethyl methyl carbonate = 15/80/5 (volume ratio) to 1.2 mol / L was used. .

All the operations were performed in a glove box (OMNI-LAB, manufactured by Vacuum atoms, filled with Ar, oxygen concentration 0.2 ppm or less, moisture concentration 0.5 ppm). Further, the coin cell members and the like were dried for 12 hours or more using a vacuum dryer (Vos-451SD, manufactured by Tokyo Rika Kikai Co., Ltd.) and then carried into the glove box.
(5) Charging / discharging evaluation of coin cell Charging / discharging evaluation was performed using the charging / discharging program shown in the said Table-1.

The initial charge / discharge efficiency (%) was calculated from the following formula.
Initial charge / discharge efficiency (%) = discharge capacity in the fourth cycle / (discharge capacity in the fourth cycle + capacity loss in the second, third, and fourth cycles (= charge capacity−discharge capacity)) × 100 (%) capacity loss ( mAh / g) = second cycle (charge capacity-discharge capacity) + third cycle (charge capacity-discharge capacity) + fourth cycle (charge capacity-discharge capacity)
Negative electrode resistance was measured as follows.
Impedance measurement was performed using the electrode of the coin cell battery which was subjected to the charge / discharge test using the charge / discharge program shown in Table-1. A Cole-Cole plot was prepared from the measurement results, and the diameter of the arc appearing in the plot was read as the interface resistance value.

<Example 2>
As an active material (A), 50 g of spheroidized natural graphite (average particle size (d50) 17 μm) is used, and the graphite and an organic compound (X) aqueous solution (Aldrich polystyrene sulfonate lithium (weight average molecular weight: 75000, 30%). Aqueous solution) Diluted by adding 49.1667 g of distilled water to 0.8333 g) and methyl ethyl ketone solution (Nittobo PAA-03-E (polyallylamine, weight average molecular weight 3000, 20% ethanol) as organic compound (Y) Solution) 0.5 g of diluted ethyl ethyl ketone 49.500 g) was placed in a flask and stirred, and the solvent was distilled off by heating to obtain a powdery non-aqueous secondary battery negative electrode active material B. Obtained. Moreover, the electrode plate B was obtained by the same procedure as Example 1, and the charge / discharge evaluation of the coin cell was performed.

<Comparative Example 1>
Without adding the organic compound (X), the organic compound (Y), and the organic compound (Z), only the spherical natural graphite (average particle size (d50) 17 μm) particles of the active material (A) are non-aqueous secondary batteries. The electrode plate C was obtained by the same procedure as in Example 1 except that it was used as the negative electrode active material, and charge / discharge evaluation of the coin cell was performed.

<Comparative example 2>
The methyl ethyl ketone solution as the organic compound (Y) was changed to Nittobo PAA-03-E, 20% ethanol solution 2.5 g diluted with 47.5 g of methyl ethyl ketone, and the organic compound (X) and the organic compound Except not adding (Z), it carried out similarly to Example 1, obtained the powdery nonaqueous secondary battery negative electrode active material D, and performed charge-and-discharge evaluation of the coin cell.

<Comparative Example 3>
The methyl ethyl ketone solution as the organic compound (Y) was changed to a solution obtained by adding 48.75 g of methyl ethyl ketone to 1.25 g of Nittobo PAA-03-E, 20% ethanol solution, and the organic compound (X) and the organic compound Except not adding (Z), it carried out similarly to Example 1, and obtained the powdery active material E for nonaqueous secondary battery negative electrodes, and performed charging / discharging evaluation of a coin cell.

<Comparative example 4>
The methyl ethyl ketone solution as the organic compound (Y) was changed to a solution obtained by adding 47.5 g of methyl ethyl ketone to 0.25 g of Nittobo PAA-03-E, 20% ethanol solution, and diluting the organic compound (X) and the organic compound. Except not adding (Z), it carried out similarly to Example 1, obtained the powdery active material F for nonaqueous secondary battery negative electrodes, and performed charging / discharging evaluation of the coin cell.

  As mentioned above, the charging / discharging evaluation result of the coin cell in Examples 1-2 and Comparative Examples 1-4 is shown in following Table-2.

  The non-aqueous secondary battery negative electrode active material (Examples 1 and 2) containing the active material (A) and the organic compound (B) was used for the non-aqueous secondary battery negative electrodes of Comparative Examples 1, 2, 3, and 4. It can be seen that the initial charge / discharge efficiency (%) is improved and the capacity loss is reduced as compared with the active material. This is because the organic compound (B) having a π-conjugated structure and a basic group suppresses reductive decomposition of the electrolytic solution generated on the active material surface and suppresses gas generation compared to an organic compound having neither. It is thought that.

When the non-aqueous secondary battery negative electrode active material according to the present invention is used as a non-aqueous secondary battery negative electrode active material in a non-aqueous secondary battery, the initial charge and discharge efficiency is reduced while suppressing an increase in negative electrode resistance. It has been found that a well-balanced negative electrode material for a non-aqueous secondary battery can be obtained that can be further improved and that can suppress the capacity loss accompanying the charge / discharge cycle.
Therefore, the non-aqueous secondary battery negative electrode active material according to the present invention is useful for non-aqueous secondary batteries such as in-vehicle applications and power tool applications that emphasize input / output characteristics, and at the same time, It is also useful for non-aqueous secondary batteries for portable devices such as personal computers.

Claims (11)

A non-aqueous secondary battery negative electrode active material comprising an active material (A) capable of inserting / extracting lithium ions and an organic compound (B),
The active material (A) is graphite,
The organic compound (B) has a π-conjugated structure, and at least one ionic group selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and a salt thereof, and an aromatic ring A mixture of an organic compound (X) having a basic group derived from an ethylenically unsaturated group-containing amine and / or a reaction product thereof.
And the organic compound (X) and the organic compound (Y) are polymers having a weight average molecular weight of 1,000 or more and 1,000,000 or less,
Active material for non-aqueous secondary battery negative electrode. The active material for a nonaqueous secondary battery negative electrode according to claim 1 , wherein the π-conjugated structure is at least one selected from the group consisting of a benzene ring, a condensed aromatic ring, and an aromatic heterocycle. The non-aqueous secondary battery according to claim 1 or 2 , wherein the basic group is at least one selected from the group consisting of a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group. Active material for negative electrode. The non-aqueous system according to any one of claims 1 to 3, wherein the organic compound (Y) having a basic group has a unit represented by the following formula (2) or (3). Active material for secondary battery negative electrode.

(In Formula (2), R ³ ~ R ⁵ Each independently represents a hydrogen atom or an atom having 1 to 6 carbon atoms.
Rukiru group, R ⁶ Is a single bond in which no atom exists or an alkylene group having 1 to 6 carbon atoms, and R ⁷ And R ⁸ Are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. )

(In Formula (3), R ⁹ ~ R ¹² Are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; ¹³ And R ¹⁴ Are each independently an alkylene group having 1 to 6 carbon atoms, R ¹⁵ Is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ) The active material for a nonaqueous secondary battery negative electrode according to any one of claims 1 to 4 , wherein the organic compound (B) further has an ion conductive group. The active material for a non-aqueous secondary battery negative electrode according to claim 5 , wherein the organic compound (B) includes the following (1) and / or (2).
(1) A mixture of an organic compound (X) having a π-conjugated structure, an organic compound (Y) having a basic group, and an organic compound (Z) having an ion conductive group.
(2) At least two kinds of reaction products selected from the group consisting of an organic compound (X) having a π-conjugated structure, an organic compound (Y) having a basic group, and an organic compound (Z) having an ion conductive group . 7. The nonion according to claim 5 , wherein the ion conductive group is at least one selected from the group consisting of an oxyalkylene group, a sulfonyl group, boron, fluorine, a carboxyl group, a carbonyl group, a carbonate group, and a cyano group. Active material for negative electrode of water-based secondary battery. The organic compound (Z) is represented by the following general formula (1):

Wherein R ¹ and R ² are each independently a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, a glycidyl group or an epoxy group, and AO is an oxyalkylene group having 2 to 5 carbon atoms. And n is an integer from 1 to 50)
The active material for nonaqueous secondary battery negative electrodes of Claim 6 or 7 which is a compound represented by these. The non-aqueous two according to any one of claims 6 to 8 , wherein a content of the organic compound (Z) in the active material with respect to the organic compound (Y) is 1% by mass or more and 300% by mass or less. Active material for secondary battery negative electrode. A current collector and an active material layer formed on the current collector, wherein the active material layer contains the active material for a non-aqueous secondary battery negative electrode according to any one of claims 1 to 9. A negative electrode for a non-aqueous secondary battery. A nonaqueous secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for a nonaqueous secondary battery according to claim 10 .