JP6895988B2 - Materials for lithium-ion secondary batteries, positive electrode mixture, positive electrodes for lithium-ion secondary batteries and lithium-ion secondary batteries - Google Patents

Description

The present invention relates to a material for a lithium ion secondary battery, a positive electrode mixture, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery.

Lithium-ion secondary batteries are secondary batteries with high energy density, and are widely used as power sources for electronic devices such as portable information terminals such as notebook computers and smartphones by taking advantage of their characteristics.

In general, a lithium ion secondary battery mainly comprises a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and an electrolytic solution containing an electrolyte. ..

In recent years, with the increasing functionality of portable information terminals, there is a strong demand for the development of lithium ion secondary batteries having an excellent capacity retention rate after a charge / discharge cycle.

In order to suppress a decrease in the capacity retention rate, (1) a method using a fluorine-based salt and a phosphonoacetate compound as an electrolyte and a zirconium-containing lithium cobalt composite oxide as a positive electrode active material (see, for example, Patent Document 1). (2) A method using a fluorinated cyclic carbonate and a fluorinated chain ester as an electrolytic solution (see, for example, Patent Document 2), (3) Lithium cobalt oxide in which a rare earth compound is fixed on a part of the surface as a positive electrode active material. (For example, see Patent Document 3) and the like have been proposed.

Japanese Unexamined Patent Publication No. 2014-127256 Japanese Unexamined Patent Publication No. 2014-110122 Japanese Unexamined Patent Publication No. 2013-179095

However, it has been clarified by the studies by the present inventors that it is difficult to sufficiently suppress the decrease in the capacity retention rate even with the methods described in Patent Documents 1 to 3 when used at a high voltage. For example, the following two causes can be considered. First, hydrogen fluoride (HF) generated when the water contained in the lithium ion secondary battery _{reacts with a fluorine-containing electrolyte such as lithium hexafluorophosphate (LiPF 6} ) is caused by the positive electrode active material. It is conceivable that metal ions such as cobalt are eluted. Secondly, it is conceivable that the eluted metal ions such as cobalt are reprecipitated on the negative electrode or the like.

The present invention has been made in view of the above circumstances, and is a material for a lithium ion secondary battery and a positive electrode mixture having an excellent ability to adsorb metal ions and hydrogen fluoride, and a thium ion secondary battery manufactured by using these. It is an object of the present invention to provide a positive electrode for use and a lithium ion secondary battery.

In view of the above circumstances, the specific means for solving this problem are as follows.
<1> A lithium ion secondary battery which is an aluminum silicate compound composite containing an aluminum silicate compound having an element molar ratio (Si / Al ratio) of silicon and aluminum of 1.0 to 5.0 and carbon. Material for.

<2> The material for a lithium ion secondary battery according to <1>, wherein the chlorine ratio (RCL) calculated by the following formula is 1% or less.
RCl (%) = (Cl ratio (mass%)) / (Al ratio (mass%) + Si ratio (mass%)) x 100

<3> and the peak area A of the oxidation point in the vicinity of 1490cm ^-1, which derived from pyridine adsorption IR spectrum, the ratio of the oxidation point which is calculated by the following equation from the peak area B of the hydrogen bonds in the vicinity of 1446cm ^-1 (RA) is The material for a lithium ion secondary battery according to <1> or <2>, which is less than 25%.
RA (%) = A / B x 100

<4> The mass loss rate between 350 ° C. and 850 ° C. measured using a differential thermal-thermogravimetric analyzer (TG-DTA) is 0.5% to 30%, <1> to <3. > The material for a lithium ion secondary battery according to any one of the items.

<5> The material for a lithium ion secondary battery according to any one of <1> to <4>, wherein the volume average particle diameter measured by a laser diffraction type particle size distribution measuring device is 0.1 μm to 50 μm.

<6> The material for a lithium ion secondary battery according to any one of <1> to <5>, wherein the element molar ratio (Si / Al) of silicon to aluminum is 1.5 to 3.0.

<7> A positive electrode mixture containing the lithium ion secondary battery material according to any one of <1> to <6> and a positive electrode active material.

<8> The content of the lithium ion secondary battery material is 0.01 wt% to 10 wt% based on the total amount of the positive electrode material, positive electrode according to <7>.

<9> A positive electrode for a lithium ion secondary battery containing the material for a lithium ion secondary battery according to any one of <1> to <6>.

<10> A lithium ion secondary battery comprising the positive electrode for the lithium ion secondary battery according to <9>.

According to the present invention, a material and a positive electrode mixture for a lithium ion secondary battery having an excellent ability to adsorb metal ions and hydrogen fluoride, and a positive electrode and a lithium ion secondary battery for a thium ion secondary battery manufactured by using these. The purpose is to provide.
Since the material for a lithium ion secondary battery of the present invention is excellent in the ability to adsorb metal ions and hydrogen fluoride, the lithium ion secondary battery using the material for a lithium ion secondary battery of the present invention has a reduced capacity retention rate. Tends to be suppressed.

It is sectional drawing which shows typically an example (cylindrical type) of the shape of a lithium ion secondary battery. It is a graph which shows the relationship between the adsorption amount of Co ion, and the Si / Al ratio of the prepared aluminum silicate compound complex. It is a graph which shows the relationship between the adsorption amount of hydrogen fluoride and the Si / Al ratio of the prepared aluminum silicate compound complex.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including element steps and the like) are not essential unless otherwise specified. The same applies to the numerical values and their ranges, and does not limit the present invention.

In the present specification, the term "process" includes not only a process independent of other processes but also the process if the purpose of the process is achieved even if the process cannot be clearly distinguished from the other process. Is done.
In the numerical range indicated by using "~" in the present specification, the numerical values before and after "~" are included as the minimum value and the maximum value, respectively.
In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. Good. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
In the present specification, the content or content of each component in the composition refers to the content of each component in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. It means the total content or content of substances.
In the present specification, the particle size of each component in the composition is a mixture of the plurality of particles existing in the composition unless otherwise specified, when a plurality of particles corresponding to each component are present in the composition. Means a value for.
In the present specification, the term "layer" or "membrane" refers to a part of the region in addition to the case where the layer or the membrane is formed in the entire region when the region where the layer or the membrane exists is observed. The case where only is formed is also included.
As used herein, the term "laminated" refers to stacking layers, and two or more layers may be bonded or the two or more layers may be removable.

<Material for lithium-ion secondary battery>
The material for a lithium ion secondary battery of the present embodiment contains an aluminum silicate compound having an element molar ratio (Si / Al ratio) of silicon and aluminum of 1.0 to 5.0 and carbon (hereinafter, aluminum). Also referred to as a silicate compound complex).

In the lithium ion secondary battery manufactured by using the material for the lithium ion secondary battery of the present embodiment, a decrease in the capacity retention rate is suppressed. The reason is not necessarily clear, but it is considered that the aluminum silicate compound complex adsorbs hydrogen fluoride generated by the reaction between the water contained in the battery and the fluorine-containing electrolyte in the electrolytic solution. It is presumed that this is because the precipitation of lithium fluoride, which is a resistance component, and the change in the crystal structure of the positive electrode active material are suppressed. It is also presumed that by adsorbing metal ions such as cobalt eluted from the positive electrode active material due to hydrogen fluoride, reprecipitation of the metal ions at the negative electrode and the like is suppressed.

Further, according to the studies by the present inventors, it was found that the above effect is more remarkable when the Si / Al ratio of the aluminum silicate compound complex is in the range of 1.0 to 5.0. The reason is not necessarily clear, but it is presumed that when the Si / Al ratio is within the above range, the adsorption capacity of hydrogen fluoride and metal ions is superior.

The state (arrangement relationship, etc.) of the aluminum silicate compound and carbon in the aluminum silicate compound complex is not particularly limited. For example, it is preferable to provide carbon on the aluminum silicate compound, and it is more preferable to provide carbon on the surface of the aluminum silicate compound. The carbon may be provided in part or in whole on the aluminum silicate compound.
Examples of the aluminum silicate compound complex include those in which all or part of the surface of the particulate aluminum silicate compound is coated with carbon.
The presence or absence of carbon in the aluminum silicate compound complex can be confirmed by, for example, laser Raman spectroscopy with an excitation wavelength of 532 nm.

Examples of the aluminum silicate compound in the aluminum silicate compound complex include allophane, kaolin, zeolite, saponite and imogolite, which are aluminum silicates. Among these, an amorphous aluminum silicate compound having an easily adjustable specific surface area is preferable from the viewpoint of improving cycle characteristics.

The amorphous aluminum silicate compound is an aluminum silicate having an elemental molar ratio Si / Al in the range of 0.3 to 5.0. Examples of the amorphous aluminum silicic acid compound include those having a composition represented by nSiO ₂ , Al ₂ O ₃ , mH ₂ O [n = 0.6 to 10.0, m = 0 or more].

The amorphous aluminum silicate compound does not have a clear peak showing a mullite structure in the powder X-ray diffraction spectrum using CuKα ray as an X-ray source, and has a broad peak in the vicinity of 2θ = 10 ° to 30 °. .. As the X-ray diffractometer, for example, Geigerflex RAD-2X (manufactured by Rigaku Co., Ltd.) can be used. The specific measurement conditions are as follows.
-Measurement conditions-
Divergence slit: 1 °
Scattering slit: 1 °
Light receiving slit: 0.30 mm
X-ray output: 40kV, 40mA

The amorphous aluminum silicate compound may be synthesized or a commercially available product may be used. When synthesizing an amorphous aluminum silicate compound, a step of mixing a solution containing silicate ions and a solution containing aluminum ions to obtain a reaction product, and the reaction product in an aqueous medium in the presence of an acid. It has a step of heat treatment, and can have other steps if necessary. From the viewpoint of the yield of the obtained reaction product, the formation of a structure, and the like, a washing step of desalting and solid separation is performed at least after the heat treatment step, preferably both before and after the heat treatment step. It is preferable to have.

By desalting and removing coexisting ions from the solution containing the reaction product and then heat-treating in the presence of an acid, an amorphous aluminum silicate compound having excellent adsorption capacity for metal ions and hydrogen fluoride can be efficiently produced. Can be manufactured. Examples of coexisting ions include sodium ion, chloride ion, perchlorate ion, nitrate ion, sulfate ion and the like.

The method of adding carbon to the amorphous aluminum silicate compound is not particularly limited. For example, a method of coating an amorphous aluminum silicate compound with an organic compound (carbon precursor) that changes to carbon by heat treatment and changing this carbon precursor to carbon can be mentioned.

As a method of coating the amorphous aluminum silicic acid compound with the carbon precursor, a wet method in which the amorphous aluminum silicic acid compound is added to the carbon precursor dissolved or dispersed in the solvent and then the solvent is removed by heating or the like. , A dry method, a vapor phase method such as a CVD method, etc., in which a mixture obtained by mixing a carbon precursor and an amorphous aluminum silicic acid compound with each other and kneading the mixture while applying a shearing force can be mentioned. From the viewpoint of cost and reduction of manufacturing process, a dry method or a vapor phase method that does not use a solvent is preferable.

The type of carbon precursor is not particularly limited. For example, ethylene heavy end pitch, crude oil pitch, coal tar pitch, asphalt decomposition pitch, pitch generated by thermal decomposition of polyvinyl chloride and the like, synthetic pitch obtained by polymerizing naphthalene and the like in the presence of super strong acid, and the like can be mentioned. Further, polyvinyl chloride, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral and the like can be used as the thermoplastic carbon precursor, and phenol resin, furan resin and the like can be used as the thermosetting carbon precursor.

Examples of the method for converting the carbon precursor into carbonaceous material include a method of heating in an inert atmosphere. The heating conditions in this case are not particularly limited, and can be determined in consideration of the carbonization rate of the carbon precursor and the like. For example, it is preferable to heat in the range of 800 ° C. to 1300 ° C. in an inert atmosphere. When the heating temperature is 800 ° C. or higher, the carbonization of the carbon precursor progresses sufficiently, the specific surface area of the aluminum silicate compound composite does not become too large, and the initial irreversible capacity tends to be difficult to increase. When the heating temperature is 1300 ° C. or lower, the specific surface area does not become too low, and the resistance tends to be less likely to increase. Examples of the inert atmosphere include nitrogen, argon, helium, and a mixed gas thereof.

The element molar ratio (Si / Al ratio) of silicon and aluminum of the aluminum silicate compound complex is preferably 1.0 to 5.0, and more preferably 1.5 to 3.0.

The Si / Al ratio of the aluminum silicate compound complex can be calculated from the values obtained for silicon and aluminum by performing elemental analysis of the measurement sample. Elemental analysis can be performed by inductively coupled plasma (ICP) emission spectroscopy.

Examples of the apparatus used for elemental analysis by ICP emission spectroscopic analysis include "P-4010" manufactured by Hitachi, Ltd.

The aluminum silicate compound complex preferably has a chlorine ratio (RCl) of 1% or less, more preferably 0.1% or less, and further preferably less than 0.1%. When the chlorine ratio (RCl) is 1% or less, the decrease in life due to deterioration (elution, film formation, etc.) of the positive electrode active material caused by a chlorine-derived compound (hydrogen chloride, etc.) tends to be suppressed. Further, when the chlorine ratio (RCl) is less than 0.1%, the expansion of the battery due to the gas generated by the reaction between chlorine and the electrolytic solution tends to be suppressed.

In the present specification, the chlorine ratio (RCl) means the ratio (%) of the Cl content in the aluminum silicate compound complex to the total content of Al and Si. Specifically, it is a value calculated by the following formula (1) from the value obtained for each element by performing elemental analysis in the measurement sample. Elemental analysis can be measured using the same methods and equipment as the Si / Al ratio.

RCl (%) = (Cl ratio (mass%)) / (Al ratio (mass%) + Si ratio (mass%)) × 100 ... (1)

Aluminum silicate compound complex is calculated and the peak area A of the oxidation point in the vicinity of 1490cm ^-1, which derived from pyridine adsorption IR spectrum, the following equation from the peak area B of the hydrogen bonds in the vicinity of 1446cm ^-1 (2) The oxidation point ratio (RA) is preferably less than 25%.
RA (%) = A / B x 100 ... (2)
The ratio of oxidation points (RA) is preferably less than 25%, more preferably less than 20%. When the ratio of oxidation points is less than 25%, it becomes difficult to adsorb water, and the decrease in life tends to be suppressed. Further, when the ratio of oxidation points (RA) is less than 20%, the expansion of the battery caused by the reaction between the functional group and the electrolytic solution tends to be suppressed.

The oxidation point of the aluminum silicate compound complex can be measured from the pyridine adsorption IR spectrum obtained by infrared spectroscopy. The pyridine-adsorbed IR spectrum can be obtained using, for example, a Fourier transform infrared spectrophotometer (for example, "Cary670" from Agilent Technologies).

Specifically, the oxidation point of the aluminum silicate compound complex is measured as follows.
The cell filled with the sample is evacuated at 500 ° C. for 1 hour and then cooled to 30 ° C. Next, pyridine gas is introduced into the cell while being heated to 100 ° C. and adsorbed for 5 minutes. Then, the pyridine is physically adsorbed by heating to 150 ° C. and exhausting for 60 minutes. Then, the mixture is cooled to 30 ° C. and the IR spectrum is measured.

From the obtained IR spectrum, the peak area A of the oxidation point and the peak area B of the hydrogen bond are calculated by the following method, and the value calculated by the formula (2) is calculated using each of the calculated peak areas. Ratio (RA).

<Calculation of peak area A of oxidation point>
Draw a straight baseline in the region ^{from 1485 cm -1} to 1500 cm ^{-1 of the IR spectrum.} The maximum peak near 1490 cm ^{-1 in the} meantime is separated into peaks using a Gaussian function, and the area of the portion surrounded by the baseline is obtained.
<Calculation of peak area B of hydrogen bond>
Draw a straight baseline in the region ^{from 1430 cm -1} to 1460 cm ^{-1 of the IR spectrum.} The largest peak near 1446 cm ^{-1 in the} meantime is separated into peaks using the Gaussian function, and the area of the part surrounded by the baseline is obtained.

From the viewpoint of input / output characteristics and cycle characteristics, the mass loss rate between 350 ° C. and 850 ° C. measured using differential thermal-thermogravimetric analysis (TG-DTA) of the aluminum silicate compound complex is 0. 5% to 30% is preferable, 2% to 25% is more preferable, and 5% to 20% is further preferable. When the mass reduction rate of 350 ° C. to 850 ° C. is within the above range, the resistance increase due to the reaction between the surface of the aluminum silicate compound complex and the electrolytic solution tends to be suppressed, and the adsorption of hydrogen fluoride or the like tends to be suppressed. It tends to be superior to the ability.

The mass reduction rate of the aluminum silicate compound complex at 350 ° C. to 850 ° C. is the value obtained by the following formula (3).

Mass reduction rate (%) = {(W1-W2) / W1} x 100 ... (3)

In the formula (3), W1 is the mass (g) of the object to be measured after the temperature is raised from 25 ° C. to 350 ° C. at a heating rate of 10 ° C./min under the flow of dry air and held at 350 ° C. for 20 minutes. , W2 is the mass (g) of the object to be measured after the temperature is raised from 350 ° C. to 850 ° C. at a heating rate of 10 ° C./min under the flow of dry air and held at 850 ° C. for 20 minutes.

Examples of the apparatus used for the analysis by TG-DTA include "TG-DTA-6200 type" of SII Nanotechnology Co., Ltd.

When the aluminum silicate compound composite is a particle, the volume average particle diameter (D50) measured by the laser diffraction type particle size distribution measuring device is selected according to the desired size of the aluminum silicate compound composite and is 0. It is preferably 1 μm to 50 μm, more preferably 0.2 μm to 20 μm, and even more preferably 0.5 μm to 10 μm.

When the volume average particle diameter (D50) of the aluminum silicate compound composite is 0.1 μm or more, the viscosity of the positive electrode mixture does not become too high when producing a positive electrode using the positive electrode mixture described later, and the work The sex tends to be well maintained. When the volume average particle size (D50) of the aluminum silicate compound composite is 50 μm or less, it tends to be difficult to draw streaks when the positive electrode mixture is applied onto the current collector.

The volume average particle size (D50) of the aluminum silicate compound complex is preferably 0.5 μm or more from the viewpoint of cost reduction required for pulverization, and 10 μm or less from the viewpoint of the efficiency of adsorption of hydrogen fluoride or the like. Is preferable.

The volume average particle size (D50) of the aluminum silicate compound complex is measured using a laser diffraction method. The measurement by the laser diffraction method can be performed using, for example, a laser diffraction type particle size distribution measuring device (SALD3000J, Shimadzu Corporation). Specifically, an aluminum silicate compound complex is dispersed in a dispersion medium such as water to prepare a dispersion, and a volume cumulative distribution curve is obtained from the small diameter side of this dispersion using a laser diffraction type particle size distribution measuring device. When drawn, the particle size (D50) when the cumulative volume is 50% is calculated as the volume average particle size.

The BET specific surface area of the aluminum silicate compound complex ^{is preferably 80 m 2} / g or less, ^{more preferably 40 m 2} / g or less, and 20 m ² / g or less from the viewpoint of cycle characteristics and storage characteristics. It is more preferable to have. The lower limit of the BET specific surface area is not particularly limited, but from the viewpoint of improving the adsorption capacity for hydrogen fluoride and metal ions ^{, it is preferably 1 m 2} / g or more, and more preferably 2 m ² / g or more. It is more preferably 3 m ² / g or more.

The BET specific surface area of the aluminum silicate compound complex is measured from the nitrogen adsorption capacity according to JIS Z 8830 (2001). As the evaluation device, for example, a nitrogen adsorption measuring device (AUTOSORB-1, QUANTACHROME) or the like can be used. When measuring the BET specific surface area, it is assumed that the water adsorbed on the sample surface and structure affects the gas adsorption capacity. Therefore, first, a pretreatment for removing water by heating is performed. ..

In the pretreatment, the measurement cell containing 0.05 g of the measurement sample is depressurized to 10 Pa or less with a vacuum pump and then heated at 110 ° C. After holding in this state for 3 hours or more, the mixture is naturally cooled to room temperature (25 ° C.) while maintaining the reduced pressure. After this pretreatment, the evaluation temperature is set to 77K, and the evaluation pressure range is measured as a relative pressure (equilibrium pressure with respect to saturated vapor pressure) of less than 1.

<Positive electrode mixture>
The positive electrode mixture of the present embodiment contains the material for the lithium ion secondary battery of the present embodiment and the positive electrode active material. The lithium ion secondary battery having a positive electrode formed by using the positive electrode mixture of the present embodiment suppresses a decrease in the capacity retention rate even when used at a high voltage.

The details and preferred embodiments of the lithium ion secondary battery material contained in the positive electrode mixture are the same as those described for the lithium ion secondary battery material of the present embodiment. The details and preferred embodiments of the positive electrode active material contained in the positive electrode mixture are the same as those described for the lithium ion secondary battery described later.

The content of the lithium ion secondary battery material in the positive electrode mixture may be, for example, 0.01% by mass to 10% by mass, and 0.05% by mass to 5% by mass, based on the total amount of the positive electrode mixture. Is preferable. The mass ratio of the lithium ion secondary battery material to the positive electrode active material (lithium ion secondary battery material / positive electrode active material) in the positive electrode mixture may be, for example, 0.009 to 9.8. It is preferably 0.045 to 4.9.

<Positive electrode for lithium-ion secondary battery>
The positive electrode for a lithium ion secondary battery of the present embodiment contains the material for a lithium ion secondary battery of the present embodiment. For example, it can be produced by a known method using the positive electrode mixture of the present embodiment.
<Lithium-ion secondary battery>
The lithium ion secondary battery of the present embodiment includes the positive electrode for the lithium ion secondary battery of the present embodiment. In the lithium ion secondary battery of the present embodiment, a decrease in the capacity retention rate is suppressed.

First, the outline of the lithium ion secondary battery of the present embodiment will be briefly described. The lithium ion secondary battery has a positive electrode and a negative electrode, and a separator through which lithium ions can pass is usually arranged between the positive electrode and the negative electrode.

When charging a lithium ion secondary battery, a charger is connected between the positive electrode and the negative electrode. During charging, the lithium ions inserted in the positive electrode active material of the positive electrode are desorbed and released into the electrolytic solution. Lithium ions released into the electrolytic solution move in the electrolytic solution, pass through the separator, and reach the negative electrode. The lithium ions that reach the negative electrode are inserted into the negative electrode active material of the negative electrode.

When discharging the lithium ion secondary battery, an external load is connected between the positive electrode and the negative electrode. At the time of discharge, the lithium ions inserted in the negative electrode active material of the negative electrode are desorbed and released into the electrolytic solution. At this time, electrons are emitted from the negative electrode. Then, the lithium ions released into the electrolytic solution move in the electrolytic solution, pass through the separator, and reach the positive electrode. Lithium ions that reach the positive electrode are inserted into the positive electrode active material of the positive electrode. By inserting lithium ions into the positive electrode active material, electrons flow into the positive electrode. In this way, electrons move from the negative electrode to the positive electrode, so that discharge is performed.

As described above, charging and discharging are performed by inserting or removing lithium ions between the positive electrode active material and the negative electrode active material. An actual configuration example of the lithium ion secondary battery will be described later (see, for example, FIG. 1). Hereinafter, the positive electrode, the negative electrode, the electrolytic solution, the separator and other constituent members of the lithium ion secondary battery will be described.

1. 1. Positive electrode The positive electrode includes the material for the lithium ion secondary battery of the present embodiment and the positive electrode active material. Specifically, for example, the positive electrode has a current collector and a positive electrode mixture layer provided on both sides or one side of the current collector, and the positive electrode mixture layer is for the lithium ion secondary battery of the present embodiment. Includes material and positive electrode active material. The positive electrode may contain other materials such as a conductive material, a binder, a thickener, and a dispersion solvent, if necessary.

(Positive electrode active material)
The positive electrode active material contained in the positive electrode may be only one type or two or more types. From the viewpoint of improving the energy density, it is preferable to contain a lithium-containing composite metal oxide or a lithium-containing phosphoric acid compound. The lithium-containing composite metal oxide or lithium-containing phosphoric acid compound is a metal oxide or phosphoric acid compound containing lithium and a metal other than lithium. The metal other than lithium contained in the lithium-containing composite metal oxide or the lithium-containing phosphoric acid compound may be only one kind or two or more kinds.

The lithium-containing composite metal oxide or lithium-containing phosphoric acid compound is preferably a metal oxide or lithium-containing phosphoric acid compound containing lithium and a transition metal. In the metal oxide containing lithium and the transition metal or the lithium-containing phosphoric acid compound, a part of the transition metal may be replaced with an element (dissimilar element) different from the transition metal. Specific examples of the dissimilar elements include Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, B and the like, and include Mn, Al, Co, Ni and At least one selected from the group consisting of Mg is preferable.

The lithium-containing composite metal oxide, for _{example, Li x CoO 2, Li x} NiO 2, Li x MnO 2, Li x Co y Ni 1-y O 2, Li x Co y M 1 1-y O z (Li _{In x} Co _y M ¹ _{1-y Oz} , M ¹ is at least one selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Cu, Zn, Al, Cr, Pb, Sb, V and B. (Indicates the element of the species.), Li _x Ni _1-y M ² _{y Oz} (in Li _x Ni _1-y M ² _{y Oz} , M ² is Na, Mg, Sc, Y, Mn, Fe, Co, Indicates at least one element selected from the group consisting of Cu, Zn, Al, Cr, Pb, Sb, V and B), Li _x Mn ₂ O ₄ and Li _x Mn _2-y M ³ _y O ₄ ( In Li _x Mn _2-y M ³ _y O ₄ , M ³ is at least selected from the group consisting of Na, Mg, Sc, Y, Fe, Co, Cu, Zn, Al, Cr, Pb, Sb, V and B. It indicates one kind of element.). Here, x is in the range of 0 <x ≦ 1.2, y is in the range of 0 to 0.9, and z is in the range of 2.0 to 2.3. Further, the x value indicating the molar ratio of lithium increases or decreases depending on charging and discharging.

Examples of the lithium-containing phosphoric acid compound include LiMPO ₄ and Li ₂ MPO ₄ F (in each of the above formulas, M is Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, etc. It represents at least one element selected from the group consisting of Pb, Sb, V and B). As the lithium-containing phosphoric acid compound, an olivine-type lithium salt is preferable, and LiFePO ₄ is more preferable.

The positive electrode active material may contain a compound other than the lithium-containing composite metal oxide or the lithium-containing phosphoric acid compound. Examples of such a compound include chalcogen compounds and manganese dioxide. Examples of the chalcogen compound include titanium disulfide and molybdenum disulfide.

The positive electrode active material may be in the form of particles, and is preferably in the state of secondary particles formed by aggregating primary particles. When the positive electrode active material is in the state of secondary particles, the expansion and contraction of the positive electrode active material due to charging and discharging are relaxed as compared with the case where the positive electrode active material is only primary particles, and the positive electrode activity due to the stress generated by the expansion and contraction is relaxed. Deterioration such as destruction of substances and cutting of conductive paths tends to occur less easily.

When the positive electrode active material is in the form of particles, its shape is not particularly limited, and examples thereof include a massive shape, a polyhedral shape, a spherical shape, an elliptical spherical shape, a plate shape, a needle shape, and a columnar shape. Of these, spherical or elliptical spherical shapes are preferable. When the shape of the positive electrode active material is spherical or elliptical spherical, the degree of orientation of the positive electrode active material in the electrode is smaller than in the case of a shape having a large aspect ratio such as a plate shape, and the electrode expands during charging and discharging. Shrinkage tends to be suppressed. In addition, when preparing a positive electrode mixture, it tends to be easily mixed with other materials such as a conductive material.

The positive electrode active material is preferably in the state of secondary particles formed by aggregating primary particles, and the shape of the secondary particles is preferably spherical or elliptical.

The volume average particle size (D50) measured by the laser diffraction type particle size distribution measuring device of the positive electrode active material is not particularly limited. From the viewpoint that the desired tap density can be easily obtained, the volume average particle diameter (D50) of the positive electrode active material may be 0.1 μm or more, preferably 0.5 μm or more, and more preferably 1 μm or more. It is preferably 3 μm or more, and more preferably 3 μm or more. From the viewpoint of electrode formability and improvement of battery performance, the volume average particle size (D50) of the positive electrode active material may be 20 μm or less, preferably 18 μm or less, more preferably 16 μm or less, and 15 μm or less. The following is more preferable.

The volume average particle size (D50) of the positive electrode active material means the volume average particle size (D50) of the secondary particles when the positive electrode active material is in the state of secondary particles. The volume average particle size (D50) of the positive electrode active material is measured in the same manner as the volume average particle size (D50) of the lithium ion secondary battery material (aluminum silicate compound composite) of the present embodiment.

When the positive electrode active material is in the state of secondary particles, the average particle size of the primary particles forming the secondary particles is not particularly limited. From the viewpoint of improving the reversibility of charge / discharge, the average particle size of the primary particles may be 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.08 μm or more, and 0. It is more preferably 1. μm or more. From the viewpoint of improving battery performance such as output characteristics, the average particle size of the primary particles may be 3 μm or less, preferably 2 μm or less, more preferably 1 μm or less, and 0.6 μm or less. Is even more preferable.

When the positive electrode active material is in the state of secondary particles, the average particle size of the primary particles is, for example, scanning electron microscope / energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscope / energy dispersive X. It can be measured by line spectroscopy (TEM-EDX) or the like.

The BET specific surface area of the positive electrode active material is not particularly limited. From the viewpoint of improving the battery performance, it is preferable that the BET specific surface area of the positive electrode active material is 0.1 m ² / g or more, more preferably 0.2 m ² / g or more, 0.3 m ² / g The above is more preferable. From the viewpoint of electrode formation, the BET specific surface area of the positive electrode active material ^{is preferably 4.0 m 2} / g or less, ^{more preferably 2.5 m 2} / g or less, and 1.5 m ² / g or less. Is more preferable.

The BET specific surface area of the positive electrode active material is measured by the same method as the method for measuring the BET specific surface area of the aluminum silicate compound complex described above.

(Conductive material)
The positive electrode preferably contains a conductive material from the viewpoint of improving battery performance. Examples of the conductive material include natural graphite, artificial graphite, graphite such as fibrous graphite (graphite), and carbon black. From the viewpoint of improving input / output characteristics, acetylene black is preferable among carbon blacks.

When carbon black is used as the conductive material, the carbon black preferably has an average particle size of 20 nm to 100 nm, and the average particle size is preferably 20 nm to 100 nm, from the viewpoint of dispersibility in the positive electrode mixture and the input / output characteristics of the battery. The particles are more preferably 30 nm to 80 nm, and further preferably the particles having an average particle size of 40 nm to 60 nm.

When graphite is contained as the conductive material, the graphite is preferably particles having an average particle size of 1 μm to 10 μm. Further, it is preferable that the carbon network layer (d002) of graphite in the X-ray wide-angle diffraction method is 0.3354 nm to 0.337 nm.

When the conductive material is a particle, the shape of the particle includes a granular shape, a flake shape, a spherical shape, a columnar shape, an irregular shape, and the like. Here, "granular" is not an irregular shape but a shape having substantially the same dimensions (JIS Z2500: 2000). The flake-like (fragmentary) shape is a plate-like shape (JIS Z2500: 2000), and is also called a scale-like shape because it is a thin plate-like shape like scales. In this embodiment, a scanning electron microscope is used. Analysis is performed from the result of the observation by, and the particles having an aspect ratio (particle diameter a / average thickness t) in the range of 2 to 100 are made into flakes. The particle size a referred to here is defined as the value of the square root of the area S when the flake-shaped particles are viewed in a plane. “Spherical” is a shape that is almost spherical (see JIS Z2500: 2000). Further, the shape does not necessarily have to be spherical, and the ratio (DL) / (DS) (sometimes referred to as spherical coefficient or sphericity) of the major axis (DL) and minor axis (DS) of the particles is 1. Those in the range of 0 to 1.2 are included in the "sphere". When the particles are spherical, the major axis (DL) is the particle size. Examples of the columnar shape include a substantially cylindrical shape and a substantially polygonal prism shape. When the particles are columnar, the height of the column is the particle size.

The average particle size of the conductive material is an arithmetic mean value of values measured for all of the particle images in the image taken by a scanning electron microscope taken at 200,000 times.

When a conductive material is used, its content is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and 0.5% by mass or more with respect to the total amount of the positive electrode mixture. Is more preferable. The upper limit of the content of the conductive material is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less. When the content of the conductive material is within the above range, the battery capacity and input / output characteristics tend to be superior.

(Bundling material)
The positive electrode preferably contains a binder from the viewpoint of obtaining adhesiveness between the positive electrode mixture, the current collector, and the positive electrode active material. The type of binder is not particularly limited. Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethylmethacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluorine. Rubber-like polymers such as rubber, isoprene rubber, butadiene rubber, and ethylene-propylene rubber; styrene / butadiene / styrene block copolymer or hydrogen additive thereof, EPDM (ethylene / propylene / diene ternary copolymer), styrene / Thermoplastic elastomeric polymers such as ethylene / butadiene / ethylene copolymer, styrene / isoprene / styrene block copolymer or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate Soft resin-like polymer such as copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, polytetra Fluorine-based polymers such as fluoroethylene / vinylidene fluoride copolymers; polymer compositions having ionic conductivity of alkali metal ions (particularly lithium ions) and the like can be mentioned.

As the binder, one type may be used alone, or two or more types may be used in combination. From the viewpoint of the stability of the positive electrode, it is preferable to use a fluorine-based polymer such as polyvinylidene fluoride (PVdF) or a polyvinylidene fluoride / vinylidene fluoride copolymer. When the positive electrode mixture layer is formed on the current collector by a wet method, it is preferable to select a binder having good solubility or dispersibility in the dispersion solvent contained in the positive electrode mixture.

When the positive electrode mixture contains a binder, the content thereof is preferably 0.5% by mass or more, more preferably 1% by mass or more, and 2% by mass, based on the total amount of the positive electrode mixture. The above is more preferable. The upper limit of the content of the binder is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and preferably 10% by mass or less. Especially preferable. By setting the content of the binder in the above range, the battery performance such as cycle characteristics tends to be superior.

(Dispersion solvent)
When the positive electrode mixture is in the state of a slurry, it may contain a dispersion solvent.
The dispersion solvent is not particularly limited as long as it can dissolve or disperse the material contained in the positive electrode mixture, and may be an aqueous solvent or an organic solvent.
Examples of the aqueous solvent include water, a mixed solvent of alcohol and water, and the like, and examples of the organic solvent include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, and acrylic. Methyl acid, diethyltriamine, N, N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethylsulfoxide, benzene, xylene, quinoline, pyridine, methyl Examples thereof include naphthalene and hexane.

If the positive electrode mixture is in the form of a slurry, a thickener may be included to adjust the viscosity. The thickener is not particularly limited, and examples thereof include polymer compounds such as carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein, and salts of these polymer compounds. The thickener may be used alone or in combination of two or more.

When the positive electrode mixture contains a thickener, the content thereof is not particularly limited. From the viewpoint of coatability of the positive electrode mixture, it is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and 0.5% by mass or more with respect to the total amount of the positive electrode mixture. Is more preferable. The content of the thickener is preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass or less, based on the total amount of the positive electrode mixture.

(Current collector)
The material of the current collector is not particularly limited, and examples thereof include metal materials such as aluminum, stainless steel, nickel-plated steel, titanium, and tantalum, and carbonaceous materials such as carbon cloth and carbon paper. Among them, a metal material is preferable, and aluminum is more preferable.

The shape of the current collector is not particularly limited, and materials processed into various shapes can be used. Examples of the shape when the current collector is a metal material include a metal foil, a metal column, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, and a foamed metal. Examples of the shape when the current collector is a carbonaceous material include a carbon plate, a carbon thin film, and a carbon cylinder. Of these, a metal thin film is preferable. The thin film may be in the form of a mesh.

When the shape of the current collector is a thin film, its thickness is not particularly limited. From the viewpoint of obtaining sufficient strength as a current collector, the thickness of the current collector may be 1 μm or more, preferably 3 μm or more, and more preferably 5 μm or more. From the viewpoint of obtaining sufficient flexibility and workability, the thickness of the current collector may be 1 mm or less, preferably 100 μm or less, and more preferably 50 μm or less.

As a method of forming a positive electrode mixture layer on a current collector using a positive electrode mixture, a method of forming a positive electrode mixture into a sheet and crimping the positive electrode mixture to the current collector (dry method), a slurry-like positive electrode Examples thereof include a method of applying a mixture to a current collector and drying it (wet method).

The positive electrode mixture layer formed on the current collector is preferably consolidated by a hand press, a roller press, or the like in order to improve the packing density of the positive electrode active material.

From the viewpoint of output characteristics, it is preferable density of the positive-electrode mixture layer is ^{3.0g / cm 3 ~4.0g / cm 3} . Further, the single-side coating of the current collector (in the case of wet process sided coating amount after drying) is preferably ^{100g / m 2 ~300g / m 2} .

2. Negative electrode The negative electrode contains a negative electrode active material. Specifically, for example, the negative electrode has a current collector and a negative electrode mixture layer provided on both sides or one side of the current collector, and the negative electrode mixture layer contains a negative electrode active material. The negative electrode may contain other materials such as a conductive material, a binder, a thickener, and a dispersion solvent, if necessary.

(Negative electrode active material)
The negative electrode active material is not particularly limited as long as it is a substance that can occlude and release lithium ions. For example, carbonaceous materials, metal composite oxides, oxides or nitrides of Group 4 elements such as tin, germanium, and silicon, lithium alone, lithium alloys such as lithium aluminum alloys, and lithium alloys such as Sn and Si are formed. Possible metals and the like. From the viewpoint of safety, at least one selected from the group consisting of carbonaceous materials and metal composite oxides is preferable. One type of negative electrode active material may be used alone, or two or more types may be used in combination. The negative electrode active material may be in the form of particles, for example.

Examples of the carbonaceous material include amorphous carbon material, natural graphite, composite carbonaceous material in which a film of amorphous carbon material is formed on natural graphite, artificial graphite (resin raw material such as epoxy resin and phenol resin, or petroleum). It is obtained by firing a graphite-based raw material obtained from coal or the like).

From the viewpoint of high current density charge / discharge characteristics, the metal composite oxide preferably contains one or both of titanium and lithium, and more preferably contains lithium.

Among the negative electrode active materials, the carbonaceous material has high conductivity, and is particularly excellent in low temperature characteristics and cycle stability. Among the carbonaceous materials, graphite is preferable from the viewpoint of increasing the capacity. For graphite, the carbon network layer (d002) in the X-ray wide-angle diffraction method is preferably less than 0.34 nm, and more preferably 0.3354 nm or more and 0.337 nm or less. A carbonaceous material satisfying such conditions may be referred to as pseudoanisotropic carbon.

(Conductive material)
The negative electrode mixture containing the negative electrode active material may further contain a conductive material. As the conductive material, a highly conductive carbonaceous material such as a graphitic carbon material, an amorphous carbon material, or activated carbon can be used. Specific examples thereof include graphite (graphite) such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon materials such as needle coke. One type of conductive material may be used alone, or two or more types may be used in combination. When the negative electrode mixture contains a conductive material, there is a tendency to obtain effects such as reducing the resistance of the electrode.

When a carbonaceous material is used as the negative electrode active material and a carbonaceous material is used as the conductive material, the conductive material is a carbonaceous material having different properties from the carbonaceous material (first carbonaceous material) used as the negative electrode active material (1). (Second carbonaceous material) is preferable. Examples of the above-mentioned properties include X-ray diffraction parameters, median diameter, aspect ratio, BET specific surface area, orientation ratio, Raman R value, tap density, true density, pore distribution, circularity, ash content, and the like. Shows one or more properties.

When the negative electrode mixture contains a conductive material, the content thereof is not particularly limited. From the viewpoint of the effect of improving the conductivity, the content of the conductive material may be 1% by mass or more, preferably 2% by mass or more, and 3% by mass or more with respect to the total amount of the negative electrode mixture. Is more preferable. From the viewpoint of suppressing an increase in the initial irreversible capacity, the content of the conductive material may be 45% by mass or less, preferably 40% by mass or less, based on the total amount of the negative electrode mixture.

(Bundling material)
The negative electrode mixture may contain a binder. The binder is not particularly limited, and examples of the binder may be included in the positive electrode mixture. One type of binder may be used alone, or two or more types may be used in combination.

When the negative electrode mixture contains a binder, the content thereof is not particularly limited. From the viewpoint of suppressing a decrease in the strength of the negative electrode mixture, the content of the binder is preferably 0.1% by mass or more, preferably 0.2% by mass or more, based on the total amount of the negative electrode mixture. More preferably, it is more preferably 0.5% by mass or more. From the viewpoint of suppressing an increase in the proportion of the binder that does not contribute to the battery capacity and a decrease in the battery capacity, the content of the binder is 20% by mass or less with respect to the total amount of the negative electrode mixture. It is often 15% by mass or less, more preferably 10% by mass or less, and further preferably 8% by mass or less.

When a rubber-like polymer typified by styrene-butadiene rubber (SBR) is used as the main component of the binder, the content of the binder is 0.1% by mass or more with respect to the total amount of the negative mixture. It is preferable that it is 0.2% by mass or more, and more preferably 0.5% by mass or more. Further, it may be 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less with respect to the total amount of the negative electrode mixture.

When a fluorine-based polymer typified by polyvinylidene fluoride is used as the main component of the binder, the content of the binder may be 1% by mass or more with respect to the total amount of the negative electrode mixture, and is 2% by mass. It is preferably 3% by mass or more, and more preferably 3% by mass or more. Further, it may be 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less with respect to the total amount of the negative electrode mixture.

(Thickening material)
The negative electrode mixture may contain a thickener to adjust the viscosity. The thickener is not particularly limited, and examples thereof include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. As the thickener, one type may be used alone, or two or more types may be used in combination.

When the negative electrode mixture contains a thickener, its content is not particularly limited. From the viewpoint of coatability of the negative electrode mixture, the content of the thickener may be 0.1% by mass or more, preferably 0.2% by mass or more, and 0.5% by mass or more. Is more preferable. From the viewpoint of suppressing a decrease in battery capacity or an increase in resistance between negative electrode active materials, the content of the thickener may be 5% by mass or less, preferably 3% by mass or less, and 2% by mass or less. Is more preferable.

(Current collector)
The material of the current collector used for the negative electrode is not particularly limited, and examples thereof include metal materials such as copper, nickel, stainless steel, and nickel-plated steel. Of these, copper is preferable from the viewpoint of ease of processing and cost.

The shape of the current collector is not particularly limited, and materials processed into various shapes can be used. Specific examples include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, foamed metal and the like. Among them, a metal thin film is preferable, and a copper foil is more preferable. The copper foil includes a rolled copper foil formed by a rolling method and an electrolytic copper foil formed by an electrolytic method, both of which are preferably used as a current collector.

The thickness of the current collector is not particularly limited, but if the thickness is less than 25 μm, it is stronger to use a strong copper alloy (phosphor bronze, titanium copper, Corson alloy, Cu—Cr—Zr alloy, etc.) than pure copper. It is preferable from the viewpoint of.

No particular method is formed for producing a negative electrode using a negative electrode mixture and a current collector. For example, it can be produced by forming a negative electrode mixture layer on a current collector using a negative electrode mixture in the same manner as the above-mentioned positive electrode.

3. 3. Electrolyte The electrolyte contains an electrolyte and a non-aqueous solvent that dissolves it. The electrolytic solution may contain an additive if necessary. As the electrolyte, one type may be used alone, or two or more types may be used in combination. Further, as the electrolytic solution, one containing a fluorine-containing electrolyte is preferable.

The electrolyte preferably contains a lithium salt, and more preferably contains _{lithium hexafluorophosphate (LiPF 6).} When the electrolyte comprises a LiPF _6, even using only LiPF _6, it may be used in combination of a lithium salt other than LiPF _6.

Lithium salts other than LiPF ₆ include inorganic fluoride salts such as _{LiBF 4} , _{LiAsF 6} , LiSbF _{6 ; perhalogenates such as LiClO 4} , LiBrO ₄ , LiIO ₄ ; inorganic chloride salts such as _{LiAlCl 4 ; LiCF 3} Perfluoroalcan sulfonates such as SO ₃ ; perfluoro such as LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₉ ) Alcan sulfonylimide salt; perfluoroalkanesulfonylmethide salt _{such as LiC (CF 3} SO ₂ ) ₃ ; Li [PF ₅ (CF ₂ CF ₂ CF ₃ )], Li [PF ₄ (CF ₂ CF ₂ CF ₃ ) ₂ ], Li [PF ₃ (CF ₂ CF ₂ CF ₃ ) ₃ ], Li [PF ₅ (CF ₂ CF ₂ CF ₂ CF ₃ )], Li [PF ₄ (CF ₂ CF ₂ CF ₂ CF ₃ ) ₂ ], Fluoroalkyl fluoride phosphates such as Li [PF ₃ (CF ₂ CF ₂ CF ₂ CF ₃ ) ₃ ]; lithium bis (oxalate) bolate, lithium difluorooxalate bolate and the like can be mentioned.

When the electrolyte contains LiPF ₆ and other lithium salts, _{the content of LiPF 6} is preferably 10% by mass or more, preferably 50% by mass or more, of the total lithium salt from the viewpoint of battery performance. More preferred.

The concentration of the electrolyte in the electrolytic solution is not particularly limited. From the viewpoint of sufficiently obtaining the electric conductivity of the electrolytic solution, it may be 0.5 mol / L or more, preferably 0.6 mol / L or more, and more preferably 0.7 mol / L or more. From the viewpoint of suppressing a decrease in electrical conductivity due to an increase in the viscosity of the electrolytic solution, it may be 2 mol / L or less, preferably 1.8 mol / L or less, and more preferably 1.7 mol / L or less. preferable.

The non-aqueous solvent is not particularly limited as long as it can be used as an electrolyte solvent for a lithium ion secondary battery. For example, cyclic carbonate, chain carbonate, chain ester, cyclic ether, chain ether and the like can be mentioned.

As the cyclic carbonate, those having 2 to 6 carbon atoms in the alkylene group constituting the cyclic carbonate are preferable, and those having 2 to 4 carbon atoms are more preferable. Specific examples thereof include ethylene carbonate, propylene carbonate and butylene carbonate. Of these, ethylene carbonate and propylene carbonate are preferable.

As the chain carbonate, a dialkyl carbonate is preferable, and the two alkyl groups preferably have 1 to 5 carbon atoms, and more preferably 1 to 4 carbon atoms, respectively. Specifically, symmetric chain carbonates such as dimethyl carbonate, diethyl carbonate and di-n-propyl carbonate, asymmetric chain carbonates such as methyl ethyl carbonate, methyl-n-propyl carbonate and ethyl-n-propyl carbonate and the like. Can be mentioned. Of these, dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate are preferable.

Examples of the chain ester include methyl acetate, ethyl acetate, propyl acetate, methyl propionate and the like. Of these, methyl acetate is preferable from the viewpoint of improving low temperature characteristics.

Examples of the cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran and the like. Of these, tetrahydrofuran is preferable from the viewpoint of improving input / output characteristics.

Examples of the chain ether include dimethoxyethane and dimethoxymethane.

One type of non-aqueous solvent may be used alone, or two or more types may be used in combination. Examples of the combined use of the two or more types include a combination of a solvent having a high dielectric constant such as cyclic carbonate and a solvent having a low viscosity such as a chain carbonate and a chain ester. One of the preferred combinations is a combination mainly composed of cyclic carbonate and chain carbonate. In this case, the total of the cyclic carbonate and the chain carbonate in the whole non-aqueous solvent may be 80% by volume or more, preferably 85% by volume or more, and more preferably 90% by volume or more. The volume of the cyclic carbonate with respect to the total of the cyclic carbonate and the chain carbonate may be 5% by volume or more, preferably 10% by volume or more, and more preferably 15% by volume or more. The volume of the cyclic carbonate with respect to the total of the cyclic carbonate and the chain carbonate may be 50% by volume or less, preferably 35% by volume or less, and more preferably 30% by volume or less. By using such a combination of non-aqueous solvents, the cycle characteristics and storage characteristics of the battery tend to be further improved.

Specific examples of preferable combinations of cyclic carbonates and chain carbonates include ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and methyl ethyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate. And methyl ethyl carbonate, ethylene carbonate, diethyl carbonate and methyl ethyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate and the like.

The additive is not particularly limited as long as it is an additive for a non-aqueous electrolyte solution of a lithium ion secondary battery. Examples thereof include heterocyclic compounds containing at least one of nitrogen and sulfur, cyclic carbonates having a double bond in the molecule such as cyclic carboxylic acid ester and vinylene carbonate, and cyclic carbonates containing halogen atoms such as fluoroethylene carbonate. ..
In addition to the above additives, other additives such as an overcharge prevention material, a negative electrode film forming material, a positive electrode protective material, and a high input / output material may be used depending on the required function.

From the viewpoint of cycle characteristics, it is preferable to contain vinylene carbonate as an additive. When the electrolytic solution contains vinylene carbonate, the content thereof is preferably 0.3% by mass to 2.0% by mass with respect to the entire electrolytic solution. When the content of vinylene carbonate is 0.3% by mass or more, a film can be sufficiently formed on the negative electrode, and the decomposition of the electrolytic solution tends to be suppressed. When the content of vinylene carbonate is 2.0% by mass or less, the increase in internal pressure under high temperature and high voltage tends to be suppressed. The content of vinylene carbonate is more preferably 0.5% by mass to 1.5% by mass with respect to the entire electrolytic solution. When the content of vinylene carbonate is 0.5% by mass or more, vinylene carbonate tends to be suppressed from being decomposed and consumed and depleted. When the content of vinylene carbonate is 1.5% by mass or less, the decomposition of vinylene carbonate during high-temperature storage tends to suppress the generation of gas.

4. Separator The separator is particularly long as it has ion permeability while electronically insulating between the positive electrode and the negative electrode, and has sufficient resistance to oxidizing property on the positive electrode side and reducing property on the negative electrode side. Not limited. Examples of the material (material) of the separator satisfying such characteristics include resins, inorganic substances, and glass fibers.

Examples of the resin include olefin polymers, fluoropolymers, cellulosic polymers, polyimides, nylons and the like. Specifically, it is preferable to select from materials that are stable against non-aqueous electrolytes and have excellent liquid retention properties, and porous sheets, non-woven fabrics and the like made from polyolefins such as polyethylene and polypropylene are more preferable.

Examples of the inorganic substance include oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate. Examples of the separator using an inorganic substance include those in which a fiber-shaped or particle-shaped inorganic substance is attached to a thin-film-shaped substrate such as a non-woven fabric, a woven fabric, or a microporous film. As the thin film-shaped base material, those having a pore diameter of 0.01 μm to 1 μm and a thickness of 5 μm to 50 μm are preferably used. As another example, a fiber-shaped or particle-shaped inorganic substance is used as a composite porous layer using a binder such as a resin. Further, a separator obtained by forming this composite porous layer on the surface of a positive electrode or a negative electrode may be used as a separator. For example, a composite porous layer in which alumina particles having a 90% particle size of less than 1 μm are bound to a fluororesin as a binder may be formed on the surface of the positive electrode to serve as a separator.

5. Other components The lithium ion secondary battery may be provided with a cleavage valve as other components. By opening the cleavage valve, it is possible to suppress an increase in pressure inside the battery and improve safety.

In addition, a component that releases an inert gas (for example, carbon dioxide) as the temperature rises may be provided. By providing such a component, when the temperature inside the battery rises, the cleavage valve can be opened quickly due to the generation of an inert gas, and safety can be improved. Examples of the material used for the constituent parts include lithium carbonate, polyalkylene carbonate resin and the like.

(Lithium-ion secondary battery)
First, an example of the embodiment when the lithium ion secondary battery is a laminated type will be described. The laminated lithium ion secondary battery can be manufactured, for example, as follows. First, the positive electrode and the negative electrode are cut into a square shape, and tabs are welded to the respective electrodes to prepare positive and negative electrode terminals. Next, the positive electrode, the separator (insulating layer), and the negative electrode are laminated in this order to prepare a laminate, which is housed in the laminate pack, and the positive and negative electrode terminals are taken out of the laminate pack. The non-aqueous electrolyte is then injected into the laminate pack to seal the openings in the laminate pack. Examples of the material of the laminate pack include aluminum and the like.

Next, an example of the embodiment in the case where the lithium ion secondary battery has a columnar shape of 18650 type will be described with reference to the drawings. As shown in FIG. 1, the lithium ion secondary battery 1 has a battery container 6 made of nickel-plated steel and having a bottomed cylindrical shape. The battery container 6 houses an electrode group 5 formed by winding a strip-shaped positive electrode plate 2 and a negative electrode plate 3 via a separator 4. The separator 4 may be, for example, a polyethylene porous sheet having a width of 58 mm and a thickness of 30 μm. On the upper end surface of the electrode group 5, a ribbon-shaped positive electrode tab terminal made of aluminum whose one end is fixed to the positive electrode plate 2 is led out. The other end of the positive electrode tab terminal is located above the electrode group 5 and is ultrasonically bonded to the lower surface of the disk-shaped battery lid that serves as the positive electrode external terminal. On the other hand, on the lower end surface of the electrode group 5, a ribbon-shaped negative electrode tab terminal made of copper whose one end is fixed to the negative electrode plate 3 is led out. The other end of the negative electrode tab terminal is joined to the inner bottom of the battery container 6 by resistance welding. Therefore, the positive electrode tab terminal and the negative electrode tab terminal are led out to both end faces of the electrode group 5, respectively. The entire circumference of the outer peripheral surface of the electrode group 5 is provided with an insulating coating (not shown). The battery lid is caulked and fixed to the upper part of the battery container 6 via an insulating resin gasket. Therefore, the inside of the lithium ion secondary battery 1 is sealed. Further, a non-aqueous electrolytic solution (not shown) is injected into the battery container 6.

In the present embodiment, the capacity ratio of the negative electrode to the positive electrode (negative electrode capacity / positive electrode capacity) is preferably 1.03 to 1.8, preferably 1.05 to 1.4, from the viewpoint of safety and energy density. Is more preferable.
Here, the negative electrode capacity indicates [discharge capacity of the negative electrode], and the positive electrode capacity indicates [initial charge capacity of the positive electrode-irreversible capacity of the negative electrode or the positive electrode, whichever is larger]. Here, the [discharge capacity of the negative electrode] is defined as being calculated by the charging / discharging device when the lithium ions inserted in the negative electrode active material are desorbed. Further, [initial charge capacity of the positive electrode] is defined as being calculated by the charging / discharging device when lithium ions are desorbed from the positive electrode active material.
The capacity ratio of the negative electrode to the positive electrode can also be calculated from, for example, "discharge capacity of the lithium ion secondary battery / discharge capacity of the negative electrode". The discharge capacity of the lithium ion battery is, for example, 4.4 V, 0.1 C to 0.5 C, and 0.1 C to 0 after performing constant current constant voltage (CCCV) charging with an end time of 2 to 15 hours. It can be measured under the condition when a constant current (CC) is discharged to 2.5V at .5C.
For the discharge capacity of the negative electrode, a negative electrode obtained by measuring the discharge capacity of the lithium ion secondary battery is cut into a predetermined area, a lithium metal is used as a counter electrode, and a unipolar cell is produced via a separator impregnated with an electrolytic solution. Then, after charging with a constant current constant voltage (CCCV) at 0V, 0.1C to 0.5C, and a final current of 0.01C, the constant current (CC) was discharged to 1.5V at 0.1C to 0.5C. It can be calculated by measuring the discharge capacity per predetermined area under the above conditions and converting it into the total area when used as the negative electrode of the lithium ion battery. In this unipolar cell, the direction in which lithium ions are inserted into the negative electrode active material is defined as charging, and the direction in which the lithium ions inserted in the negative electrode active material are desorbed is defined as discharging.
In addition, C means "current value (A) / battery discharge capacity (Ah)".

<Aluminum silicate compound complex>
The aluminum silicate compound composite of the present embodiment contains an aluminum silicate compound having an element molar ratio (Si / Al ratio) of silicon and aluminum of 1.0 to 5.0, and carbon.
The details and preferred embodiments of the aluminum silicate compound composite of the present embodiment are the same as the details and preferred embodiments of the aluminum silicate compound composite used as the material for the lithium ion secondary battery described above.

The aluminum silicate compound composite of the present embodiment is preferably used as a material for a lithium ion secondary battery, and is used as a material for a lithium ion secondary battery of a lithium ion secondary battery containing a fluorine-containing electrolyte in an electrolytic solution. Is more preferable.
The application of the aluminum silicate compound composite of the present embodiment is not limited to the material for the lithium ion secondary battery, and since it exhibits excellent adsorption ability to metal ions and the like, for example, an air purification filter. It can be used as a component of water treatment materials, light absorption films, electromagnetic wave shield films, organic solvents, non-aqueous solvent ion exchange filters, semiconductor encapsulants and electronic materials.

Hereinafter, the present embodiment will be described in more detail based on the examples. The present invention is not limited to the following examples.

[Manufacturing Example 1]
_{Water glass (sodium silicate No. 3, Na 2} O · nSiO ₂ · mH ₂ O) (500 mL) having a Si concentration of 2 mol / L was added to an aqueous solution of aluminum sulfate (500 mL) having an Al concentration of 1 mol / L, and stirred for 30 minutes. did. A 1 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 7. The pH-adjusted solution was stirred for 30 minutes and then desalted by pressure filtration. To the precipitate after desalting, 1 mol / L sulfuric acid was added to adjust the pH to 4, and the mixture was stirred for 30 minutes. The solution was then placed in a dryer and heated at 98 ° C. for 48 hours. A 1 mol / L sodium hydroxide aqueous solution was added to the heated solution to adjust the pH to 9. The salt in the solution was aggregated by adjusting the pH, the aggregate was precipitated by the same pressure filtration as above, and then the supernatant was discharged to perform desalting. The precipitate obtained after the desalting treatment was dried at 110 ° C. for 16 hours to recover the particle agglomerates. The recovered particle agglomerates were pulverized with a jet mill to obtain particulate aluminum silicate compounds.
Next, the obtained aluminum silicate compound and polyvinyl alcohol powder (Wako Pure Chemical Industries, Ltd.) were mixed at a mass ratio of 100:70 and baked at 1000 ° C. for 1 hour in a nitrogen atmosphere to be derived from polyvinyl alcohol. A particulate aluminum silicate compound complex was prepared in which the carbon silicate compound was provided on the aluminum silicate compound.

[Manufacturing Example 2]
_{Water glass (sodium silicate No. 3, Na 2} O · nSiO ₂ · mH ₂ O) (429 mL) having a Si concentration of 2 mol / L was added to an aqueous aluminum sulfate solution (571 mL) having an Al concentration of 1 mol / L, and stirred for 30 minutes. did. Then, the same operation as in Production Example 1 (pH adjustment, desalting, 98 ° C. aging, drying, pulverization, etc.) was carried out to obtain a particulate aluminum silicate compound. Next, a particulate aluminum silicate compound complex was prepared in the same manner as in Production Example 1.

[Manufacturing Example 3]
_{Water glass (sodium silicate No. 3, Na 2} O · nSiO ₂ · mH ₂ O) (600 mL) having a Si concentration of 2 mol / L was added to an aqueous aluminum sulfate solution (400 mL) having an Al concentration of 1 mol / L, and stirred for 30 minutes. did. Then, the same operation as in Production Example 1 (pH adjustment, desalting, 98 ° C. aging, drying, pulverization, etc.) was carried out to obtain a particulate aluminum silicate compound. Next, a particulate aluminum silicate compound complex was prepared in the same manner as in Production Example 1.

[Manufacturing Example 4]
_{Water glass (sodium silicate No. 3, Na 2} O · nSiO ₂ · mH ₂ O) (333 mL) having a Si concentration of 2 mol / L was added to an aqueous solution of aluminum sulfate (667 mL) having an Al concentration of 1 mol / L, and stirred for 30 minutes. did. Then, the same operation as in Production Example 1 (pH adjustment, desalting, 98 ° C. aging, drying, pulverization, etc.) was carried out to obtain a particulate aluminum silicate compound. Next, a particulate aluminum silicate compound complex was prepared in the same manner as in Production Example 1.

[Manufacturing Example 5]
To an aqueous solution of aluminum sulfate (286 mL) having an Al concentration of 1 mol / L, water glass having a Si concentration of 2 mol / L (sodium silicate No. 3, Na ₂ O · nSiO ₂ · mH ₂ O) (714 mL) was added and stirred for 30 minutes. did. Then, the same operation as in Production Example 1 (pH adjustment, desalting, 98 ° C. aging, drying, pulverization, etc.) was carried out to obtain a particulate aluminum silicate compound. Next, a particulate aluminum silicate compound complex was prepared in the same manner as in Production Example 1.

[Manufacturing Example 6]
A particulate aluminum silicate compound complex was produced in the same manner as in Production Example 1 except that the firing conditions in the carbon adhesion step were set to 900 ° C. for 1 hour.

[Manufacturing Example 7]
A particulate aluminum silicate compound complex was produced in the same manner as in Production Example 1 except that the firing conditions in the carbon adhesion step were set to 850 ° C. for 1 hour.
[Manufacturing Example 8]
Particle-like aluminum silicate in the same manner as in Production Example 1 except that the aluminum silicate compound described in Production Example 1 and polyvinyl alcohol powder (Wako Pure Chemical Industries, Ltd.) were mixed at a mass ratio of 100:45. A compound complex was prepared.
[Manufacturing Example 9]
Particle-like aluminum silicate in the same manner as in Production Example 1 except that the aluminum silicate compound described in Production Example 1 and polyvinyl alcohol powder (Wako Pure Chemical Industries, Ltd.) were mixed at a mass ratio of 100: 100. A compound complex was prepared.

[Manufacturing Example 10]
_{Water glass (sodium silicate No. 3, Na 2} O · nSiO ₂ · mH ₂ O) (91 mL) having a Si concentration of 2 mol / L was added to an aqueous aluminum sulfate solution (909 mL) having an Al concentration of 1 mol / L, and stirred for 30 minutes. did. Then, the same operation as in Production Example 1 (pH adjustment, desalting, 98 ° C. aging, drying, pulverization, etc.) was carried out to obtain a particulate aluminum silicate compound. Next, a particulate aluminum silicate compound complex was prepared in the same manner as in Production Example 1.

[Manufacturing Example 11]
_{Water glass (sodium silicate No. 3, Na 2} O · nSiO ₂ · mH ₂ O) (833 mL) having a Si concentration of 2 mol / L was added to an aqueous aluminum sulfate solution (167 mL) having an Al concentration of 1 mol / L, and stirred for 30 minutes. did. Then, the same operation as in Production Example 1 (pH adjustment, desalting, 98 ° C. aging, drying, pulverization, etc.) was carried out to obtain a particulate aluminum silicate compound. Next, a particulate aluminum silicate compound complex was prepared in the same manner as in Production Example 1.

[Manufacturing Example 12]
An aqueous sodium orthosilicate aqueous solution (500 mL) having a Si concentration of 350 mmol / L was added to an aqueous aluminum chloride solution (500 mL) having an Al concentration of 700 mmol / L, and the mixture was stirred for 30 minutes. 330 mL of a 1 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 6.1. After stirring the pH-adjusted solution for 30 minutes, centrifuge for 5 minutes at a rotation speed of 3,000 rpm using a centrifuge (Tomy Seiko Co., Ltd .: Suprema23 and standard rotor NA-16). went. After centrifugation, the supernatant solution was discharged, and the gel-like precipitate was redistributed in pure water to return to the volume before centrifugation. The desalting treatment by such centrifugation was performed three times.
To the gel-like precipitate obtained after the discharge of the supernatant for the third desalting treatment, 135 mL of 1 mol / L hydrochloric acid was added to adjust the pH to 3.5, and the mixture was stirred for 30 minutes. The solution was then placed in a dryer and heated at 98 ° C. for 48 hours. To the heated solution (salt concentration 47 g / L), 188 mL of a 1 mol / L sodium hydroxide aqueous solution was added to adjust the pH to 9.1. The salts in the solution were aggregated by adjusting the pH, the aggregates were precipitated by the same centrifugation as described above, and then the supernatant was discharged. The desalting treatment of adding pure water to the precipitate after discharging the supernatant liquid and returning the volume to the volume before centrifugation was performed three times. The gel-like precipitate obtained after the discharge of the supernatant for the third desalting treatment was dried at 60 ° C. for 16 hours to recover 30 g of a particle mass. The particle mass was pulverized with a jet mill to prepare a particulate aluminum silicate compound.
Next, the particulate aluminum silicate compound and polyvinyl alcohol powder (Wako Pure Chemical Industries, Ltd.) were mixed at a mass ratio of 100:70 (aluminum oxide: polyvinyl alcohol powder), and 1 at 850 ° C. under a nitrogen atmosphere. It was fired for a long time to prepare a particulate aluminum silicate compound complex in which carbon derived from polyvinyl alcohol was provided on the aluminum silicate compound.

[Calculation of Si / Al ratio]
The elemental molar ratios of Si and Al of the aluminum silicic acid compound composites obtained in Production Examples 1 to 12 were subjected to conventional ICP emission spectroscopic analysis (ICP emission spectroscopic apparatus: P-4010 (Hitachi Co., Ltd.)). (Si / Al) was determined. The results are shown in the table.

[Evaluation of crystal structure]
The crystal structures of the aluminum silicate compound composites obtained in Production Examples 1 to 12 were evaluated using an X-ray diffractometer (Geigerflex RAD-2X, manufactured by Rigaku Co., Ltd.). As a result of the measurement, the aluminum silicate compound composites obtained in Production Examples 1 to 12 did not have a clear peak showing a mullite structure, and had an amorphous peak in the vicinity of 2θ = 10 ° to 30 °. It was confirmed that it was an aluminum silicate compound. The measurement conditions are shown below.

-Measurement conditions-
Divergence slit: 1 °
Scattering slit: 1 °
Light receiving slit: 0.30 mm
X-ray output: 40kV, 40mA

[Evaluation of metal ion adsorption capacity]
The metal ion adsorption ability of the aluminum silicate compound composites obtained in Production Examples 1 to 5 and 10 to 10 to 12 was evaluated as follows.
An electrolytic solution containing 1 M of LiPF ₆ (ethylene carbonate: dimethyl carbonate: diethyl carbonate by volume ratio 1: 1: 1) was prepared, and Co (BF ₄ ) ₂ was dissolved therein to prepare a 500 ppm Co solution. did. To this Co solution (5 g), 0.05 g of each of the aluminum silicate compound complexes was added, and the mixture was stirred for 30 minutes and then allowed to stand overnight at room temperature.
The Co solution before the addition of the aluminum silicate compound complex and the supernatant of the Co solution after standing were filtered using a filter with a pore size of 0.45 μm, and the Co ion concentration (ppm) was obtained using an ICP emission spectroscope. ) Was measured respectively.
The difference between the Co ion concentration (500 ppm) of the initial Co solution (before the addition of the aluminum silicate compound complex) and the Co ion concentration (ppm) of the supernatant after adsorption (after standing) was determined. The Co adsorption capacity (mg / g) was calculated by multiplying the difference value by the amount of the Co solution (5 g) and dividing by the mass (0.05 g) of the aluminum silicate compound complex. The relationship between the measurement result and the Si / Al ratio of the aluminum silicate compound complex is shown in FIG.

[Evaluation of hydrogen fluoride adsorption capacity]
The hydrogen fluoride adsorbing ability of the aluminum silicate compound composites obtained in Production Examples 1 to 5 and 12 was evaluated as follows.
_{First, 1 mol / L of lithium hexafluorophosphate (LiPF 6} ) and 0.5% by mass of vinylene carbonate (VC) were added to a mixed solvent having an ethylene carbonate (EC): ethyl methyl carbonate (EMC) volume ratio of 3: 7. A dissolved electrolytic solution (40 g) was prepared. Then, the aluminum silicate compound complex (0.4 g) vacuum-dried at 120 ° C. for 10 hours was added to the electrolytic solution, stirred for 10 minutes, and then allowed to stand at room temperature for 3 hours.
Regarding the supernatant of the electrolytic solution before the addition of the aluminum silicate compound complex and the electrolytic solution after standing, the hydrogen fluoride concentration (ppm) was determined by using ion chromatography (ICS-2000, manufactured by Thermo Fisher SCIENTIFIC). It was measured.
The difference between the hydrogen fluoride concentration of the initial electrolytic solution (before the addition of the aluminum silicate compound complex) and the hydrogen fluoride concentration (ppm) of the supernatant after adsorption (after standing) was determined. The hydrogen fluoride adsorption capacity (mg / g) was calculated by multiplying the difference value by the amount of the electrolytic solution (40 g) and dividing by the mass (0.4 g) of the aluminum silicate compound complex. The relationship between the measurement result and the Si / Al ratio of the aluminum silicate compound complex is shown in FIG.

[Calculation method of chlorine ratio (RCl)]
The chlorine ratio (RCl) of the aluminum silicate compound complex obtained in Production Examples 1 to 12 is the ratio of each element detected from the SEM-EDX (S-4800, manufactured by Hitachi High-Technologies Corporation) measurement. Therefore, it was calculated by the above-mentioned formula (1).

[Calculation method of oxidation point ratio (RA)]
The oxidation points of the aluminum silicate compound composites obtained in Production Examples 1 to 12 were measured using a Fourier transform infrared spectrophotometer (Cary 670, manufactured by Agilent Technologies). Specifically, the cell filled with the sample was exhausted at 500 ° C. for 1 hour and then cooled to 30 ° C. Next, pyridine gas was introduced into the cell while being heated to 100 ° C. and adsorbed for 5 minutes. Then, the pyridine was physically adsorbed by heating to 150 ° C. and exhausting for 60 minutes. Finally, it was cooled to 30 ° C. and the IR spectrum was measured. Also, the IR spectrum, A; calculated 1446cm analyzed peak area of the hydrogen bonds in the vicinity of ^-1 by the ratio equation described above the (RA) (2); and the peak area of the oxidation point in the vicinity of 1490cm ^-1, B did.

[Evaluation of mass reduction rate]
The mass reduction rate of the aluminum silicate compound complex obtained in Production Examples 1 to 12 at 350 ° C. to 850 ° C. was calculated by the above formula (3).

(Example 1)
[Preparation of positive electrode]
Lithium cobalt oxide (94% by mass), which is a positive electrode active material, fibrous graphite (1% by mass) and acetylene black (AB) (1% by mass) as conductive materials, and the aluminum silicic acid compound produced in Production Example 1 The composite (1% by mass) and polyvinylidene fluoride (PVDF) (3% by mass) as a binder were sequentially added and mixed. The composition of the mixture is shown in Table 1. The content of the conductive material in Table 1 is the total of fibrous graphite (1% by mass) and acetylene black (1% by mass).
Further, N-methyl-2-pyrrolidone (NMP) as a dispersion solvent was added to the above mixture and kneaded to prepare a slurry-like positive electrode mixture. This positive electrode mixture was applied to an aluminum foil having a thickness of 20 μm, which is a current collector for the positive electrode, substantially evenly and uniformly. Then, it was dried and compacted by pressing to a predetermined density. The density of the positive electrode mixture after drying was 3.6 g / cm ^3, and the single-sided coating amount of the positive electrode mixture after drying was 202 g / m ² .

[Preparation of negative electrode]
SBR (styrene-butadiene rubber) as a binder and carboxymethyl cellulose (trade name: CMC # 2200, manufactured by Daicel FineChem Co., Ltd.) as a binder are added to artificial graphite having an average particle diameter of 22 μm, which is a negative electrode active material. Added. These mass ratios were negative electrode active material: binder: thickener = 98: 1: 1. Water was added to this as a dispersion solvent and kneaded to prepare a slurry-like negative electrode mixture. A predetermined amount of this negative electrode mixture was applied to both surfaces of a rolled copper foil having a thickness of 10 μm, which is a current collector for the negative electrode, substantially evenly and uniformly. The density of the negative electrode mixture after drying was 1.65 g / cm ^3, and the one-side coating amount of the negative electrode mixture after drying was 113 g / m ² .

[Manufacturing of lithium-ion secondary battery]
The positive electrode cut into a 13.5 cm ² square is sandwiched between a polyethylene porous sheet (trade name: Hypore, manufactured by Asahi Kasei Co., Ltd., thickness 30 μm, “Hypore” is a registered trademark), and further 14.3 cm. ^A laminated body was prepared by superimposing the negative electrodes cut into 2 squares. This laminate is placed in an aluminum laminate container (trade name: aluminum laminate film, manufactured by Dai Nippon Printing Co., Ltd.), 1 mL of electrolytic solution is added, the laminate container is heat welded, and a lithium ion secondary battery for evaluation is used. Made. As the electrolytic solution, _{a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate containing 1 mol / L LiPF 6} to which 1% by mass of vinylene carbonate (VC) was added to the total amount of the mixed solution was used.

(Examples 2 to 9)
The same as in Example 1 except that the aluminum silicate compound composites obtained in Production Examples 2 to 9 were added to the positive electrode mixture instead of the aluminum silicate compound composites obtained in Production Example 1. , A lithium ion secondary battery for evaluation was prepared. The composition and evaluation results are shown in Table 1.

(Comparative Example 1)
Same as Example 1 except that the proportion of lithium cobalt oxide, which is the positive electrode active material, was 95% by mass, the single-sided coating amount of the positive electrode mixture ^{was changed to 200 g / m 2 without adding the aluminum silicate compound composite.} Then, a lithium ion secondary battery for evaluation was manufactured. The composition and evaluation results are shown in Table 1.

(Comparative Examples 2 to 4)
In the same manner as in Example 1 except that the aluminum silicate compound composites obtained in Production Examples 10 to 12 were added to the positive electrode mixture instead of the aluminum silicate compound composites obtained in Production Example 1. A lithium ion secondary battery for evaluation was produced. The composition and evaluation results are shown in Table 1.

[Evaluation of battery capacity]
The battery characteristics of the produced lithium-ion battery were evaluated by the method shown below.
First, in an environment of 25 ° C., constant current charging was performed at a current value of 0.1 C up to an upper limit voltage of 4.4 V, and then constant voltage charging was performed at 4.4 V. The charging termination condition was a current value of 0.01C. Then, a constant current discharge with a final voltage of 2.5 V was performed with a current value of 0.1 C. This charge / discharge cycle was repeated 3 times. (“C” used as a unit of current value means “current value (A) / battery capacity (Ah)”.) Further, constant current charging of 0.2 C is performed up to an upper limit voltage of 4.4 V. Subsequently, after constant voltage charging at 4.4 V (the charge termination condition was a current value of 0.02 C), constant current discharge with a termination voltage of 2.5 V was performed at a current value of 0.2 C, and this discharge was performed. The capacity at the time was taken as the battery capacity.

[Evaluation of output characteristics]
The output characteristics were calculated as follows.
After measuring the above battery capacity, constant current charging at 0.2 C was performed up to an upper limit voltage of 4.4 V, and then constant voltage charging was performed at 4.4 V. The charging termination condition was a current value of 0.02C. Then, a constant current discharge with a final voltage of 2.5 V was performed with a current value of 0.2 C, and the capacity at the time of this discharge was defined as the discharge capacity at a current value of 0.2 C. Next, 0.2C constant current charging was performed up to an upper limit voltage of 4.4V, and then constant voltage charging was performed at 4.4V (the charge termination condition was a current value of 0.02C), and then 3C. A constant current discharge with a final voltage of 2.5 V was performed with the current value, and the capacity at the time of this discharge was defined as the discharge capacity at the current value of 3C, and the output characteristics were calculated by the following formula. The results are shown in Table 1.

Output characteristics (%) = (Discharge capacity at current value 3C / Discharge capacity at current value 0.2C) x 100

[Evaluation of cycle characteristics]
The cycle characteristics were calculated as follows.
After evaluating the output characteristics under the conditions shown above, the cycle characteristics were evaluated by a cycle test in which charging and discharging were repeated. As for the charging pattern, each lithium battery was subjected to constant current charging at a current value of 1C up to an upper limit voltage of 4.4V in an environment of 45 ° C., and then constant voltage charging was performed at 4.4V. The charging termination condition was a current value of 0.1C. The discharge was 1C and constant current discharge was performed up to 2.5V. The cycle characteristics were calculated by the following formula. The results are shown in Table 1.

Cycle characteristics (%) = (Discharge capacity after 200 cycles at current value 1C / Discharge capacity after 1 cycle at current value 1C) x 100

[Evaluation of high temperature storage characteristics]
The high temperature storage characteristic (battery expansion) was calculated as follows.
After evaluating the output characteristics under the conditions shown above, the volume of the lithium ion secondary battery was measured with a high-precision electronic gravity meter (MDS-300, manufactured by Alpha Mirage Co., Ltd.). Then, at 25 ° C., constant current charging was performed at a current value of 0.1 C up to an upper limit voltage of 4.4 V, and then constant voltage charging was performed at 4.4 V. The charging termination condition was a current value of 0.01C. In the charged state, the lithium ion secondary battery was left in a constant temperature bath at 80 ° C. for 48 hours, and a high temperature storage test was carried out. After the test, the lithium ion secondary battery was taken out from the constant temperature bath, cooled to 25 ° C., and then the volume was measured with a high-precision electronic gravity meter, and the expansion rate of the lithium ion secondary battery was calculated from the following formula. The results are shown in Table 1.

Battery expansion (%) = (volume of lithium battery after high temperature storage test / volume of lithium battery before high temperature storage test) x 100

[Evaluation of Co precipitation amount]
The lithium ion secondary battery after the cycle test was disassembled, the negative electrode was washed with dimethyl carbonate, and dried. After that, the negative electrode mixture layer is peeled off from the copper foil which is the current collector, and the amount of Co precipitation (mass basis, ppm) in the negative electrode mixture layer is analyzed by ICP emission spectroscopic analysis (ICP emission spectroscopic device: P-4010 (Hitachi, Ltd.) )) Obtained from. The results are shown in Table 1.

As shown in the results of Table 1, the lithium ion secondary batteries of Examples 1 to 9 produced using the aluminum silicate compound complex were the lithium of Comparative Example 1 produced without using the aluminum silicate compound complex. The evaluation of output characteristics and cycle characteristics was better than that of the ion secondary battery. The reason for this is not always clear, but the aluminum silicate compound complex contained in the positive electrode adsorbs hydrogen fluoride in the electrolytic solution to precipitate lithium fluoride as a resistance component and the crystal structure of the positive electrode active material. It is considered that the change and the like were suppressed, and the capacity decrease and the deterioration of the output characteristics after the cycle test were suppressed. In addition, by adsorbing metal ions such as cobalt eluted from the positive electrode active material by the aluminum silicic acid compound complex located on the positive electrode, metal precipitation on the negative electrode is suppressed, resulting in volume reduction and output characteristics after the cycle test. It is considered that the deterioration of the metal was suppressed.

Among Examples 1 to 9, the lithium ion secondary batteries of Examples 1 to 6 and 8 and 9 had suppressed expansion of the batteries as compared with the lithium ion secondary batteries of Example 7. The reason for this is not necessarily clear, but since the oxidation point ratio of the aluminum silicic acid compound complex used in Examples 1 to 6 is lower than that in Example 7, less gas is generated due to the reaction with the electrolytic solution, and the solution is contained in the electrolytic solution. It is probable that due to the adsorption of hydrogen fluoride in the above, less gas such as carbon dioxide was generated by the reaction between hydrogen fluoride and lithium carbonate on the electrode.

In the lithium ion secondary batteries of Comparative Examples 2 to 4 produced by using the aluminum silicate compound composite whose Si / Al ratio is not in the range of 1.0 to 5.0, the Si / Al ratio is 1.0 to 1.0 to 5.0. Compared with the lithium ion secondary batteries of Examples 1 to 9 produced using the aluminum silicate compound composite in the range of 5.0, sufficient effects were found in improving output characteristics and cycle characteristics and suppressing battery expansion. I couldn't. The reason for this is not always clear, but the adsorption capacity of hydrogen fluoride or metal ions of the aluminum silicate compound complex is related to the Si / Al ratio, and it is sufficient when the Si / Al ratio deviates from the appropriate value. It is possible that the adsorption capacity cannot be exhibited.

1 Lithium-ion secondary battery 2 Positive electrode
3 Negative electrode 4 Separator 5 Electrode group
6 Battery container

Claims (9)

And aluminum silicate compounds elemental molar ratio of silicon to aluminum (Si / Al ratio) is 1.0 to 5.0, Ri complexes der aluminum silicate compound containing carbon, chlorine which is calculated by the following formula A material for a lithium ion secondary battery having a ratio (RCl) of 1% or less.
RCl (%) = (Cl ratio (mass%)) / (Al ratio (mass%) + Si ratio (mass%)) x 100 It is an aluminum silicate compound complex containing an aluminum silicate compound having an element molar ratio (Si / Al ratio) of silicon and aluminum of 1.0 to 5.0 and carbon, and is 1490 cm obtained from a pyridine adsorption IR spectrum. ^-1 Peak area A of the nearby oxidation point and 1446 cm ^-1 A material for a lithium ion secondary battery in which the ratio of oxidation points (RA) calculated from the peak area B of hydrogen bonds in the vicinity by the following formula is less than 25%.
RA (%) = A / B x 100 It is an aluminum silicate compound complex containing an aluminum silicate compound having an element molar ratio (Si / Al ratio) of silicon and aluminum of 1.0 to 5.0 and carbon, and is a differential heat-thermal weight analysis (TG). A material for a lithium ion secondary battery, which has a mass loss rate of 0.5% to 30% between 350 ° C. and 850 ° C. as measured using −DTA). The material for a lithium ion secondary battery according to any one of claims 1 to 3 , wherein the volume average particle diameter measured by a laser diffraction type particle size distribution measuring device is 0.1 μm to 50 μm. The material for a lithium ion secondary battery according to any one of claims 1 to 4 , wherein the elemental molar ratio (Si / Al) of silicon to aluminum is 1.5 to 3.0. A positive electrode mixture containing the lithium ion secondary battery material according to any one of claims 1 to 5 and a positive electrode active material. The content of the lithium ion secondary battery material is 0.01 wt% to 10 wt% based on the total amount of the positive electrode material, positive electrode of claim 6. A positive electrode for a lithium ion secondary battery containing the material for a lithium ion secondary battery according to any one of claims 1 to 5. A lithium ion secondary battery comprising the positive electrode for the lithium ion secondary battery according to claim 8.

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