JP2014041716A - Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative electrode material for a lithium ion secondary battery arranged so that excellent cycle characteristics can be achieved even when silicon is used, and to provide a negative electrode for a lithium ion secondary battery arranged by use of the negative electrode material, and a lithium ion secondary battery having the negative electrode.SOLUTION: A negative electrode material for a lithium ion secondary battery comprises: a solid content consisting of dispersoid produced by dispersing one or both of silicon and silicon monoxide, and transition metal chalcogenide with solvent coexisting therewith; and a conductive assistant; and a binder. A negative electrode for a lithium ion secondary battery comprises: a current collector; and a negative electrode active material layer formed on the current collector by use of such a negative electrode material for a lithium ion secondary battery. A lithium ion secondary battery comprises such a negative electrode for a lithium ion secondary battery.

Description

  The present invention relates to a negative electrode material for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery using the negative electrode material, and a lithium ion secondary battery including the negative electrode.

  A lithium ion secondary battery includes a positive electrode, a negative electrode, and an electrolyte. And a positive electrode and a negative electrode, ie, an electrode, are comprised by mix | blending an electrode active material, and normally a conductive support agent and a binder are further mix | blended. Among them, the electrode active material is an important factor related to the capacity of the lithium ion secondary battery, and conventionally, graphite (graphite) is mainly used as the negative electrode active material.

  On the other hand, silicon attracts attention as a negative electrode active material that can realize a higher capacity lithium ion secondary battery. For example, when graphite is used, the capacity is about 375 mAh / g, whereas when silicon is used, a capacity of about 4200 mAh / g can be realized.

On the other hand, when a negative electrode is formed using silicon, it is known that the negative electrode expands and contracts in the process of occluding and releasing lithium ions during charge and discharge. In the negative electrode, four lithium ions can be occluded and released with respect to one silicon atom, and when the secondary battery operates, the negative electrode can expand and contract four times. Due to this expansion and contraction during charging / discharging, the atomization of silicon proceeds in the negative electrode, current collecting performance is reduced, and the discharge capacity is greatly reduced. Thus, the lithium ion secondary battery using silicon as the negative electrode active material has a problem that the cycle characteristics are low.
On the other hand, the negative electrode comprised combining silicon oxide as a negative electrode active material and the specific metal which can occlude and discharge | release lithium ion is disclosed (refer patent document 1).

Japanese Patent No. 3157209

  However, even when the negative electrode disclosed in Patent Document 1 is used, the cycle characteristics of the lithium ion secondary battery are not always sufficient, and even when silicon is used, a lithium ion secondary battery having excellent cycle characteristics can be configured. Development of a negative electrode was desired.

  The present invention has been made in view of the above circumstances, and a negative electrode material for a lithium ion secondary battery excellent in cycle characteristics even when silicon is used, a negative electrode for a lithium ion secondary battery using the negative electrode material, and the negative electrode It is an object to provide a lithium ion secondary battery including

To solve the above problem,
In the present invention, one or both of silicon and silicon monoxide, and a solid content of a dispersion obtained by dispersing a transition metal chalcogenide in the presence of a solvent, a conductive assistant, and a binder are blended. A negative electrode material for a lithium ion secondary battery is provided.

In the negative electrode material for a lithium ion secondary battery of the present invention, the transition metal chalcogenide is preferably a transition metal sulfide.
In the negative electrode material for a lithium ion secondary battery of the present invention, the transition metal chalcogenide is preferably a chalcogenide of molybdenum, copper, tungsten, or titanium.
In the negative electrode material for a lithium ion secondary battery of the present invention, the transition metal chalcogenide is preferably molybdenum (IV) sulfide.

The present invention also provides a negative electrode for a lithium ion secondary battery comprising a negative electrode active material layer formed using the negative electrode material for a lithium ion secondary battery of the present invention on a current collector. provide.
The negative electrode for a lithium ion secondary battery according to the present invention is a liquid composition in which the negative electrode material for a lithium ion secondary battery is blended with at least one of the solvent of the dispersion and a solvent different from the solvent. The active material layer is preferably formed by applying and drying the liquid composition.

The present invention also provides a lithium ion secondary battery comprising the negative electrode for a lithium ion secondary battery of the present invention.
The lithium ion secondary battery of the present invention comprises (A) a lithium carboxylate and (B) boron trifluoride and / or boron trifluoride complex, or (E) a lithium carboxylate-boron trifluoride complex, (C) What provided the electrolyte solution with which an organic solvent is mix | blended is preferable.

  According to the present invention, a negative electrode material for a lithium ion secondary battery excellent in cycle characteristics even when silicon is used, a negative electrode for a lithium ion secondary battery using the negative electrode material, and a lithium ion secondary battery including the negative electrode Is provided.

<Anode material for lithium ion secondary battery>
The negative electrode material for lithium ion secondary batteries of the present invention (hereinafter sometimes abbreviated as “negative electrode material”) is either or both of silicon (silicon) and silicon monoxide (hereinafter abbreviated as “silicon etc.”). And a solid content of a dispersion obtained by dispersing the transition metal chalcogenide in the presence of a solvent, a conductive assistant, and a binder.
Such a negative electrode material uses the solid content in which silicon or the like and a transition metal chalcogenide are used in combination, so that the negative electrode uses silicon or the like, but the lithium ion secondary battery described later is charged and discharged (lithium). The effects of expansion and contraction are alleviated during ion storage and release. As a result, the lithium ion secondary battery has excellent cycle characteristics in which a decrease in discharge capacity is suppressed even when the charge / discharge cycle is repeated.
In this specification, “solid content” means the solid content of the dispersion unless otherwise specified.

The solid content is not particularly limited as long as it is in a dispersion obtained by dispersing silicon and the like and a transition metal chalcogenide in the presence of a solvent, and the dispersion includes silicon and the like, the transition metal chalcogenide and the solvent. What is necessary is just what was obtained by mix | blending.
In the dispersion, a part of the components other than the solvent may be dissolved in the solvent.

Silicon or the like used for the preparation of the dispersion is preferably in the form of powder, more preferably in the form of particles, for example, the average particle diameter is preferably 300 nm or less, and more preferably 200 nm or less. . By using such fine powdery silicon or the like, the solid content can be obtained in which the effects of the present invention can be obtained more remarkably.
The average particle diameter of silicon or the like can be obtained, for example, by measuring the particle diameter of about 100 arbitrary particles of silicon or the like using an electron microscope and calculating the average value.
For example, silicon can be pulverized by a known method using a ball mill or the like to adjust the average particle diameter to a desired value.

The transition metal chalcogenide used for the preparation of the dispersion contains transition metal and chalcogen as constituent elements.
The transition metal is an element from Group 3 to Group 11 of the periodic table, preferably an element in the fourth period, the fifth period, or the sixth period, and is molybdenum, copper, tungsten, or titanium. More preferred. That is, the transition metal chalcogenide is more preferably a chalcogenide of molybdenum, copper, tungsten or titanium.

  Chalcogen is an element belonging to Group 16 of the periodic table, and examples thereof include oxygen, sulfur, selenium, and tellurium. In the present invention, sulfur or oxygen is preferable, and sulfur is more preferable. That is, the transition metal chalcogenide is preferably a transition metal sulfide or oxide, and more preferably a transition metal sulfide.

Preferred examples of the transition metal chalcogenide include molybdenum sulfide (IV) (MoS ₂ ), copper sulfide (II) (CuS), tungsten sulfide (IV) (WS ₂ ), and titanium sulfide (IV) (TiS ₂ ).
The transition metal chalcogenide is preferably one that can form a layered structure such as graphite between molecules.

  The transition metal chalcogenides may be used singly or in combination of two or more. When two or more are used in combination, the combination and ratio may be appropriately selected according to the purpose. .

  In the dispersion, the ratio of the total blending amount of silicon and silicon monoxide (total blending ratio) in the total blending amount of silicon, silicon monoxide and transition metal chalcogenide is preferably 5 to 95% by mass, More preferably, it is 10-90 mass%. By being more than the lower limit, the lithium ion secondary battery has a further improved discharge capacity, and the negative electrode active material layer described later can be made thinner. Moreover, the cycle characteristics of the lithium ion secondary battery are further improved by being below the upper limit.

The solvent used for the preparation of the dispersion is one that disperses or dissolves silicon or the like and the transition metal chalcogenide (dispersion medium), and can be arbitrarily selected according to the type of the transition metal chalcogenide. Preferred examples include water, organic A solvent can be illustrated.
Preferred examples of the organic solvent in the dispersion include alcohols such as methanol, ethanol, 1-propanol and 2-propanol; linear or cyclic such as N-methylpyrrolidone (NMP) and N, N-dimethylformamide (DMF). Amides; ketones such as acetone can be exemplified.
The solvent in the dispersion may be used singly or in combination of two or more. When two or more are used in combination, the combination and ratio may be appropriately selected according to the purpose. Good.

In addition to the transition metal chalcogenide and the solvent such as silicon, the dispersion is not mixed with these (silicon, the transition metal chalcogenide and the solvent), and the conductive auxiliary agent and binder described later, and other components are blended. What was obtained may be sufficient. The said other component in a dispersion is not specifically limited, According to the objective, it can select arbitrarily.
In the case of blending other components, the ratio of the blended amount of the other components in the total amount of the blended components excluding the solvent (mixing ratio) is preferably 5% by mass or less, and preferably 2% by mass or less. It is more preferable that

The dispersion is obtained by blending and dispersing the transition metal chalcogenide such as silicon, a solvent, and other components as necessary.
Each component may be mixed and dispersed while sequentially adding them, or may be mixed and dispersed after all the components have been added. The compounding components are uniformly mixed and the dispersoid is uniformly dispersed. It only has to be done.
For example, at least a part of the solvent may be premixed with one or more selected from the group consisting of the silicon, transition metal chalcogenide, and other components, and blended as a solution or dispersion of these components. Good. The total amount of the solvent used for preparing such a solution or dispersion may be sufficient.

The mixing method of each component is not particularly limited as long as a dispersion is obtained. For example, a known method using a stirrer, a stirring blade, a ball mill, a stirrer, an ultrasonic disperser, an ultrasonic homogenizer, a revolving mixer, etc. Apply. A plurality of methods may be combined.
What is necessary is just to set suitably mixing conditions, such as mixing temperature and mixing time, according to various methods. Usually, the temperature during mixing is preferably 10 to 50 ° C, more preferably 15 to 35 ° C. The mixing time is preferably 1 to 48 hours, and more preferably 5 to 36 hours.

  The negative electrode material of the present invention is obtained by blending the solid content of the dispersion obtained above, a conductive additive, and a binder. The solid content may be, for example, taken out from the dispersion and dried, and only this (solid content) may be blended alone, for example, wet from which a part of the solvent (dispersion medium) is taken out from the dispersion. You may mix | blend in a state and may mix | blend with said dispersion | distribution as it is, without taking out from a dispersion | distribution.

  The solid content is composed of a plurality of components derived from compounding components other than the solvent at the time of preparing the dispersion, such as a mixture of silicon or the like and a transition metal chalcogenide or a component derived therefrom (hereinafter, from this viewpoint). The solid content may be abbreviated as “composite”), and it is assumed that other solid components are not included. Examples of preferable solid content include those in which the surface of silicon or the like is coated with a transition metal chalcogenide or a component derived therefrom.

The solid content is preferably in the form of powder, more preferably in the form of particles, for example, the average particle diameter is preferably 320 nm or less, and more preferably 220 nm or less. By using such a fine powdery solid, the cycle characteristics of the lithium ion secondary battery are further improved.
The average particle size of the solid content is determined by the same method as that for silicon or the like.
Moreover, solid content can adjust an average particle diameter to a desired value by the method similar to the case of said silicon | silicone.

  In the negative electrode material, the ratio (mixing ratio) of the solid content in the total content of the solid content, the conductive additive and the binder is preferably 15 to 90 mass%, and preferably 30 to 85 mass%. It is more preferable that When it is at least the lower limit value, the cycle characteristics and discharge capacity of the lithium ion secondary battery are further improved, and when it is at most the upper limit value, stable maintenance of the negative electrode structure is facilitated.

The conductive auxiliary agent may be a known one, and preferred examples thereof include graphite (graphite); carbon black such as ketjen black and acetylene black; carbon nanotubes; graphene; fullerene and the like.
The conductive auxiliary may be used alone or in combination of two or more. When two or more are used in combination, the combination and ratio may be appropriately selected depending on the purpose. .

  In the negative electrode material, the ratio (mixing ratio) of the conductive auxiliary agent in the total amount of the solid content, conductive auxiliary agent and binder is preferably 3 to 35% by mass, and 5 to 25% by mass. It is more preferable that By being more than the lower limit value, the effect by using the conductive auxiliary agent is more remarkably obtained. By being less than the upper limit value, the cycle characteristics and discharge capacity of the lithium ion secondary battery are improved, and the negative electrode structure is improved. Stable maintenance becomes easy.

The binder may be a known one, and preferable examples thereof include polyacrylic acid (PAA), lithium polyacrylate (PAALi), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF- Examples thereof include HFP), styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), polyethylene oxide (PEO), polyethylene glycol (PEG), carboxymethyl cellulose (CMC), polyacrylonitrile (PAN), and polyimide (PI).
The binder may be used alone or in combination of two or more. When two or more are used in combination, the combination and ratio may be appropriately selected according to the purpose.

  In the negative electrode material, the ratio (blending ratio) of the binder in the total blending amount of the solid content, the conductive additive and the binder is preferably 3 to 35% by mass, and preferably 5 to 25% by mass. It is more preferable. By being above the lower limit value, the negative electrode structure is more stably maintained, and by being below the upper limit value, the cycle characteristics and discharge capacity of the lithium ion secondary battery can be easily improved.

The negative electrode material may be formed by blending other components not corresponding to these in addition to the solid content, the conductive additive and the binder.
The other components in the negative electrode material are not particularly limited and can be arbitrarily selected according to the purpose, and preferably include those for dissolving or dispersing the above-described essential components (the solid content, the conductive assistant, and the binder). A solvent can be illustrated.
Such a negative electrode material further mixed with a solvent is preferably a liquid composition having fluidity at the time of use.

The solvent can be arbitrarily selected according to the type of the essential component, and preferable examples include water and organic solvents.
Preferred examples of the organic solvent in the negative electrode material include alcohols such as methanol, ethanol, 1-propanol and 2-propanol; chain or cyclic such as N-methylpyrrolidone (NMP) and N, N-dimethylformamide (DMF). Amides; ketones such as acetone can be exemplified.
The said solvent in a negative electrode material may be used individually by 1 type, may use 2 or more types together, and when using 2 or more types together, the combination and ratio may be suitably selected according to the objective. Good.

As the solvent in the negative electrode material, for example, the solvent of the dispersion can be used. That is, at the time of producing the negative electrode material, as described above, the solid content in the wet state taken out from the dispersion, or the solvent in which the solid content coexists in the dispersion, such as mixing the dispersion as it is. By blending with the (dispersion medium), a negative electrode material in which the solvent of the dispersion is blended is obtained.
Further, as the solvent in the negative electrode material, a solvent different from the solvent of the dispersion can be used. That is, a negative electrode material in which a solvent different from the solvent of the dispersion is blended by blending a solvent separately from the solvent of the dispersion, regardless of whether or not the dispersion solvent is blended, at the time of manufacturing the negative electrode material Is obtained. Here, “a solvent different from the solvent of the dispersion” means a solvent that is not brought from the dispersion, and does not necessarily mean that the solvent is different from the solvent of the dispersion. The same kind may be sufficient.
Thus, the negative electrode material in which a solvent such as the liquid composition is blended can be produced by blending at least one of the solvent of the dispersion and a solvent different from the solvent.

  The amount of the solvent in the negative electrode material is not particularly limited, and may be adjusted as appropriate according to the purpose. For example, when a negative electrode material, which is a liquid composition containing a solvent, is applied and dried to form a negative electrode active material layer to be described later, the liquid composition has a viscosity suitable for coating. What is necessary is just to adjust the compounding quantity of a solvent. Specifically, in the negative electrode material, the ratio of the total blending amount of the blending components other than the solvent in the total amount of the blending components (total blending ratio) is preferably 5 to 60% by mass, more preferably 10 to 35% by mass. It is good to adjust the compounding quantity of a solvent so that it may become.

  When blending a component other than the solvent (other solid component) as the other component at the time of producing the negative electrode material, the ratio of the blended amount of the other solid component in the total amount of the blended component other than the solvent in the negative electrode material ( The blending ratio) is preferably 10% by mass or less, and more preferably 5% by mass or less.

The said negative electrode material can be manufactured by mix | blending the said solid content, a conductive support agent, a binder, and another component as needed.
At the time of blending each component, it is preferable to add these components and thoroughly mix them by various means.
Each component may be mixed while sequentially adding them, or may be mixed after all components have been added, as long as the blended components are mixed uniformly.

  When the solvent is blended as the other component during the production of the negative electrode material, the solvent is at least partly selected from the group consisting of the solid content, a conductive additive, a binder, and other solid components. You may mix beforehand and mix | blend as a solution or dispersion liquid of these components. The total amount of the solvent used for preparing such a solution or dispersion may be sufficient.

The mixing method of each component is not specifically limited, For example, the well-known method using a stirring bar, a stirring blade, a ball mill, a stirrer, an ultrasonic disperser, an ultrasonic homogenizer, a self-revolving mixer etc. may be applied. A plurality of methods may be combined.
What is necessary is just to set suitably mixing conditions, such as mixing temperature and mixing time, according to various methods. Usually, the temperature during mixing is preferably 10 to 50 ° C, more preferably 15 to 35 ° C. Moreover, it is preferable that mixing time is 3 to 40 minutes, and it is more preferable that it is 5 to 20 minutes.

  The composition obtained by adding and mixing each component may be used as a negative electrode material as it is, or, for example, by removing a part of the blended solvent by distillation or the like, What was obtained by performing additional operations may be used as the negative electrode material.

<Anode for lithium ion secondary battery>
The negative electrode for a lithium ion secondary battery of the present invention (hereinafter sometimes abbreviated as “negative electrode”) comprises a negative electrode active material layer formed using the negative electrode material of the present invention as a current collector (negative electrode current collector). Body).
Such a negative electrode can be produced in the same manner as a known negative electrode except that the negative electrode material of the present invention is used.

The current collector may be a known one, and preferable materials include those having conductivity such as copper (Cu), aluminum (Al), titanium (Ti), nickel (Ni), and stainless steel. it can.
Moreover, it is preferable that the said electrical power collector is a sheet form, and it is preferable that the thickness is 5-20 micrometers.

  Although the thickness of a negative electrode active material layer is not specifically limited, It is preferable that it is 5-100 micrometers, and it is more preferable that it is 10-60 micrometers.

The negative electrode active material layer may be formed on the current collector using the negative electrode material.
For example, when a liquid composition containing a solvent is used as the negative electrode material, the negative electrode active material layer can be formed by coating and drying the liquid composition.

  Examples of the coating method of the liquid composition include various coating methods such as a method using various coaters such as a gravure coater, a comma coater, and a lip coater; a doctor blade method; a dipping method.

  The liquid composition may be dried by a known method under normal pressure or reduced pressure. And it is preferable that drying temperature is 40-180 degreeC. By being more than a lower limit, it can be dried in a short time, and the effect which suppresses the oxidation of a collector etc. becomes high by being less than an upper limit. The drying time may be appropriately adjusted according to the drying temperature, and can be, for example, 12 to 48 hours.

  The negative electrode active material layer may be formed directly on the current collector, or may be formed on another base material and then moved to the current collector, and may be crimped on the current collector. Good. And also when forming a negative electrode active material layer directly on a collector, you may make it crimp on a collector.

The negative electrode of the present invention uses a negative electrode material in which the solid content (composite) is blended, so that charging and discharging of a lithium ion secondary battery (lithium ion occlusion and During release), the effects of expansion and contraction are mitigated. As a result, the lithium ion secondary battery has excellent cycle characteristics.
The transition metal chalcogenide can occlude and release lithium ions, and can also act as a lithium ion conductive material. Furthermore, some transition metal chalcogenides have conductivity, such as copper (II) sulfide (CuS). Therefore, it is speculated that the negative electrode of the present invention does not hinder the insertion and release of lithium ions. Molybdenum sulfide (IV) (MoS ₂ ) has low lubricity but has lubricity, which remarkably relieves the influence of expansion and contraction of the negative electrode during charge and discharge, and is a lithium ion secondary battery It is estimated that this contributes to the improvement of the cycle characteristics.

<Lithium ion secondary battery>
A lithium ion secondary battery according to the present invention includes the negative electrode according to the present invention.
Such a lithium ion secondary battery can have the same configuration as a conventional lithium ion secondary battery except that it includes the negative electrode of the present invention. For example, in addition to the negative electrode, a positive electrode, an electrolytic solution, and a gel electrolyte Or it comprises a solid electrolyte. Furthermore, a separator may be provided between the negative electrode and the positive electrode as necessary.

  Examples of the positive electrode include a positive electrode active material layer formed using a positive electrode material in which a positive electrode active material, a conductive additive, a binder, and the like are blended on a current collector (positive electrode current collector). it can. As the positive electrode, a commercially available product may be used.

  The current collector, conductive additive, and binder in the positive electrode may all be the same as the current collector, conductive aid, and binder in the negative electrode.

As the positive electrode active material, a lithium metal acid compound represented by the general formula “LiM _x O _y (wherein M is a metal; x and y are composition ratios of metal M and oxygen O)” Can be illustrated.
Examples of such a metal acid lithium compound include lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), and the like, and olivine iron phosphate having a similar composition. Lithium (LiFePO ₄ ) can also be used.
In the above general formula, M may be a plurality of types of the lithium metal acid compound. As such a metal acid lithium compound, the general formula “LiM ¹ _p M ² _q M ³ _r O _y (formula Where M ¹ , M ² and M ³ are different types of metals; p, q, r and y are the composition ratios of the metals M ¹ , M ² and M ³ and oxygen O). What is represented can be exemplified. Here, p + q + r = x.
Examples of such a metal acid lithium compound include LiNi _0.33 Mn _0.33 Co _0.33 O ₂ .
A positive electrode active material may be used individually by 1 type, may use 2 or more types together, and when using 2 or more types together, the combination and ratio may be suitably selected according to the objective.

  Although the thickness of a positive electrode active material layer is not specifically limited, It is preferable that it is 20-60 micrometers.

  The positive electrode can be produced in the same manner as the negative electrode except that the positive electrode material is used instead of the negative electrode material.

  As the electrolytic solution, (A) lithium carboxylate, (B) boron trifluoride and / or boron trifluoride complex, and (C) an organic solvent (hereinafter referred to as “first electrolysis”). (It may be abbreviated as “liquid”).

  (A) The carboxylic acid lithium salt is an electrolyte, and the carboxy group only needs to form a lithium salt (—C (═O) —OLi). The number of carboxy groups constituting the lithium salt is as follows: There is no particular limitation. For example, when the number of carboxy groups is 2 or more, all the carboxy groups may constitute a lithium salt, or only some of the carboxy groups may constitute a lithium salt.

(A) Preferred lithium carboxylate is lithium formate (HCOOLi), lithium acetate (CH ₃ COOLi), lithium propionate (CH ₃ CH ₂ COOLi), lithium butyrate (CH ₃ (CH ₂ ) ₂ COOLi) , Lithium isobutyrate ((CH ₃ ) ₂ CHCOOLi), lithium valerate (CH ₃ (CH ₂ ) ₃ COOLi), lithium isovalerate ((CH ₃ ) ₂ CHCH ₂ COOLi), lithium caproate (CH ₃ (CH _{2) 4} COOLi) 1 monovalent lithium salts of carboxylic acids such as, lithium oxalate _((COOLi) 2), lithium malonate _(LiOOCCH 2 COOLi), lithium succinate _{((CH 2 COOLi) 2)} , lithium glutarate ( LiOOC (CH ₂ ) ₃ COOLi), adipine Lithium salt of a divalent carboxylic acid such as lithium acid ((CH ₂ CH ₂ COOLi) ₂ ); lithium salt of a monovalent carboxylic acid having a hydroxyl group such as lithium lactate (CH ₃ CH (OH) COOLi); lithium tartrate (( CH (OH) COOLi) ₂ ), lithium salt of a divalent carboxylic acid having a hydroxyl group such as lithium malate (LiOOCCH ₂ CH (OH) COOLi); lithium maleate (LiOOCCH = CHCOOLi, cis body), lithium fumarate ( Lithium salt of unsaturated monovalent carboxylic acid such as LiOOCCH = CHCOOLi, trans form); Lithium salt of trivalent carboxylic acid such as lithium citrate (LiOOCCH ₂ C (COOLi) (OH) CH ₂ COOLi) (3 having a hydroxyl group) Lithium salt of divalent carboxylic acid), and lithium formate More preferred are lithium acetate, lithium oxalate, and lithium succinate.

  (A) Lithium carboxylate may be used individually by 1 type, and may use 2 or more types together. When two or more kinds are used in combination, the combination and ratio may be appropriately selected according to the purpose.

(B) Boron trifluoride and boron trifluoride complex are those that undergo a complex formation reaction with (A) lithium carboxylate, and boron trifluoride complex is different from boron trifluoride (BF ₃ ). Coordinated to the component.

Preferred examples of the boron trifluoride complex include boron trifluoride dimethyl ether complex (BF ₃ .O (CH ₃ ) ₂ ), boron trifluoride diethyl ether complex (BF ₃ .O (C ₂ H ₅ ) ₂ ), three Boron fluoride di n-butyl ether complex (BF ₃ · O (C ₄ H ₉ ) ₂ ), boron trifluoride di tert-butyl ether complex (BF ₃ · O ((CH ₃ ) ₃ C) ₂ ), trifluoride Boron trifluoride alkyl ether complexes such as boron tert-butyl methyl ether complex (BF ₃ .O ((CH ₃ ) ₃ C) (CH ₃ )), boron trifluoride tetrahydrofuran complex (BF ₃ .OC ₄ H ₈ ) Boron trifluoride methanol complex (BF ₃ · HOCH ₃ ), boron trifluoride propanol complex (BF ₃ · HOC ₃ H ₇ ), boron trifluoride phenol A boron trifluoride alcohol complex such as a complex (BF ₃ .HOC ₆ H ₅ ) can be exemplified.
(B) As boron trifluoride and / or boron trifluoride complex, it is preferable to use the boron trifluoride complex from the viewpoint that it is easy to handle and the complex formation reaction proceeds more smoothly.

  (B) As boron trifluoride and / or a boron trifluoride complex, 1 type may be used independently and 2 or more types may be used together. When two or more kinds are used in combination, the combination and ratio may be appropriately selected according to the purpose.

  The blending amount of (B) boron trifluoride and / or boron trifluoride complex is not particularly limited, and (B) boron trifluoride and / or boron trifluoride complex or (A) lithium carboxylate type What is necessary is just to adjust suitably according to. Usually, the molar ratio of [(B) Boron trifluoride and / or boron trifluoride complex (mole number)] / [Mixed (A) moles of lithium atoms in carboxylic acid lithium salt] Is preferably 0.5 or more, and more preferably 0.7 or more. By setting it as such a range, the solubility of (A) lithium carboxylic acid salt with respect to the (C) organic solvent improves more. The upper limit of the molar ratio is not particularly limited as long as the effect of the present invention is not hindered, but is preferably 2.0, and more preferably 1.5.

(C) Although the organic solvent is not particularly limited, specific examples of preferable organic solvents include carbonate compounds such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, vinylene carbonate; γ-butyrolactone, etc. Lactone compounds; carboxylic acid ester compounds such as methyl formate, methyl acetate, and methyl propionate; ether compounds such as tetrahydrofuran and dimethoxyethane; nitrile compounds such as acetonitrile; and sulfone compounds such as sulfolane.
(C) An organic solvent may be used individually by 1 type, and may use 2 or more types together. When two or more kinds are used in combination, the combination and ratio may be appropriately selected according to the purpose.

  (C) Organic solvents are ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, vinylene carbonate, γ-butyrolactone, tetrahydrofuran, dimethoxyethane, methyl formate, methyl acetate, methyl propionate, acetonitrile and It is preferably at least one selected from the group consisting of sulfolane.

  The blending amount of the (C) organic solvent in the electrolytic solution is not particularly limited, and may be appropriately adjusted according to, for example, the type of the electrolyte. Usually, the blending amount may be adjusted so that the concentration of lithium atoms (Li) is preferably 0.2 to 3.0 mol / kg, more preferably 0.4 to 2.0 mol / kg. preferable.

Examples of the first electrolytic solution include a mixture of (E) a carboxylic acid lithium salt-boron trifluoride complex and (C) an organic solvent.
The (E) carboxylic acid lithium salt-boron trifluoride complex contains, for example, (A) a lithium carboxylic acid salt, (B) boron trifluoride and / or boron trifluoride complex, and (C ′) a solvent. (A) a carboxylic acid lithium salt and (B) boron trifluoride and / or boron trifluoride complex are reacted (hereinafter abbreviated as “reaction process”), and the reaction after the reaction. A step of removing (C ′) solvent and (B) impurities derived from boron trifluoride and / or boron trifluoride complex from the liquid (hereinafter abbreviated as “removal step”). It can be manufactured by a manufacturing method. The (E) carboxylic acid lithium salt-boron trifluoride complex obtained by such a production method is such that (A) lithium carboxylic acid salt and (B) boron trifluoride and / or boron trifluoride complex are complexed. It has been formed by reaction.

  In this production method, (A) lithium carboxylate, (B) boron trifluoride and / or boron trifluoride complex are the same as described above.

  (E) A lithium carboxylate-boron trifluoride complex may be used alone or in combination of two or more. When two or more kinds are used in combination, the combination and ratio may be appropriately selected according to the purpose.

  The (C ′) solvent does not interfere with the complex formation reaction of (A) lithium carboxylic acid salt with (B) boron trifluoride and / or boron trifluoride complex in the reaction step, and can dissolve these. Although it will not specifically limit if it is a thing, An organic solvent is preferable and what can be distilled off under a normal pressure or pressure reduction is preferable.

  The boiling point of (C ′) solvent is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, and particularly preferably 35 ° C. or higher. The boiling point of the (C ′) solvent is preferably 180 ° C. or lower, more preferably 150 ° C. or lower, and particularly preferably 120 ° C. or lower. By setting it to the lower limit value or more, the reaction solution in the reaction step can be stirred at room temperature, so that the reaction step can be performed more easily. Moreover, by setting it as the upper limit value or less, the (C ′) solvent can be more easily removed by distillation in the removing step.

Preferred examples of the organic solvent include chain carbonate compounds such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate (compounds having a carbonate ester bond in the chain structure); nitrile compounds such as acetonitrile; and cyclic ether compounds such as tetrahydrofuran. (Compounds having an ether bond in the cyclic structure); Chain ether compounds such as diethyl ether and 1,2-dimethoxyethane (compounds having an ether bond in the chain structure); Carboxylic acid esters such as ethyl acetate and isopropyl acetate A compound can be illustrated.
Among these, as the organic solvent, a chain carbonate compound, a nitrile compound, and a cyclic ether compound are preferable.

  (C ') A solvent may be used individually by 1 type and may use 2 or more types together. When two or more kinds are used in combination, the combination and ratio may be appropriately selected according to the purpose.

  In the removal step, as the impurities, (A) an excessive amount of (B) boron trifluoride and / or boron trifluoride complex remaining without reacting with the carboxylic acid lithium salt, and by-products generated therefrom More specifically, as the by-product, in the boron trifluoride complex which is the component (B), a component that was originally coordinated to boron trifluoride before the reaction can be exemplified. These impurities can be distilled off.

  (E) The 1st electrolyte solution using the lithium carboxylate-boron trifluoride complex is, for example, (A) lithium carboxylate and (B) boron trifluoride and / or boron trifluoride complex. Instead of blending, (E) by mixing a carboxylic acid lithium salt-boron trifluoride complex, (A) a carboxylic acid lithium salt, and (B) boron trifluoride and / or boron trifluoride complex. Can be obtained by the same method as the above-described first electrolytic solution. For example, the amount of (C) the organic solvent is not particularly limited, but the concentration of lithium atoms (Li) is preferably 0.2 to 3.0 mol / kg, more preferably 0.4 to 2.0 mol / kg. It is preferable to adjust the blending amount so as to be kg.

Further, as the electrolyte, lithium hexafluorophosphate as an electrolyte (LiPF _6), boron tetrafluoride lithium (LiBF _4), lithium bisfluorosulfonylimide (LiFSI), bis (trifluoromethanesulfonyl) imide (LiN (SO ₂ CF ₃ ) ₂ , LiTFSI) or other known lithium salt other than (A) carboxylic acid lithium salt dissolved in an organic solvent (hereinafter abbreviated as “second electrolyte solution”) There are also examples).

  The said electrolyte in a 2nd electrolyte solution may be used individually by 1 type, and may use 2 or more types together. When two or more kinds are used in combination, the combination and ratio may be appropriately selected according to the purpose.

Examples of the organic solvent in the second electrolytic solution are the same as the organic solvent (C) in the first electrolytic solution.
The concentration of lithium atoms (Li) in the second electrolytic solution is the same as that in the first electrolytic solution.

The first and second electrolytic solutions are both the above-mentioned essential components ((A) lithium carboxylic acid salt, (B) boron trifluoride and / or boron trifluoride complex in the first electrolytic solution, (E In addition to (a) a carboxylic acid lithium salt-boron trifluoride complex, (C) an organic solvent; a lithium salt in the second electrolytic solution, an organic solvent), an optional component is blended within the range not impairing the effects of the present invention. It may be.
The arbitrary component may be appropriately selected according to the purpose and is not particularly limited.

  The 1st and 2nd electrolyte solution can be manufactured by mix | blending the said essential component and an arbitrary component as needed. The compounding method of each component is the same as the compounding method of each component at the time of manufacture of the said negative electrode material.

  Although the material of the separator is not particularly limited, it can be exemplified by a microporous polymer film, a nonwoven fabric, glass fiber, and the like, and is preferably at least one selected from the group consisting of these materials.

  As the gel electrolyte, (A) lithium carboxylate, (B) boron trifluoride and / or boron trifluoride complex, (C) an organic solvent, and (D) a matrix polymer are blended; E) A mixture of a lithium carboxylate-boron trifluoride complex, (C) an organic solvent, and (D) a matrix polymer can be exemplified, and if necessary, in the first and second electrolytic solutions An arbitrary component may be blended. Moreover, as said gel electrolyte, what further mix | blended (D) matrix polymer with the 1st electrolyte solution can be illustrated. Here, (A) carboxylic acid lithium salt, (B) boron trifluoride and / or boron trifluoride complex, (E) carboxylic acid lithium salt-boron trifluoride complex, and (C) organic solvent are any Is the same as in the first electrolyte solution.

The gel electrolyte may be molded into a desired shape using a mold.
In the gel electrolyte, components (electrolytic solution) other than (D) the matrix polymer are retained in the matrix polymer.

  The gel electrolyte may be one in which a part of the blended (C) organic solvent is removed by drying or the like, and an organic solvent (for dilution) different from the (C) organic solvent mainly remaining in the gel electrolyte at the time of production. Organic solvent) may be blended separately, and the organic solvent for dilution may be removed during the drying.

(D) A matrix polymer is not specifically limited, A well-known thing can be used suitably in the solid electrolyte field | area.
Preferred (D) matrix polymers include polyether polymers such as polyethylene oxide and polypropylene oxide (polymers having a polyether skeleton); polyvinyl fluoride, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyfluoride. Fluorine-based polymers (polymers having fluorine atoms) such as vinylidene fluoride-hexafluoroacetone copolymer, polytetrafluoroethylene; poly (meth) methyl acrylate, poly (meth) ethyl acrylate, polyacrylamide, ethylene oxide units Examples include polyacrylic polymers such as polyacrylates (polymers having structural units derived from (meth) acrylates or acrylamides); polyacrylonitriles; polyphosphazenes; polysiloxanes Kill.

  (D) A matrix polymer may be used individually by 1 type, and may use 2 or more types together. When two or more kinds are used in combination, the combination and ratio may be appropriately selected according to the purpose.

  (D) The matrix polymer is polyethylene oxide, polypropylene oxide, polyvinyl fluoride, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-hexafluoroacetone copolymer, polytetrafluoroethylene, It is preferably at least one selected from the group consisting of polyacrylonitrile, polyphosphazene and polysiloxane.

  In the gel electrolyte, the blending amount of the (D) matrix polymer is not particularly limited, and may be appropriately adjusted according to the type, but the blending amount of the (D) matrix polymer in the total amount of blending components is 2 to 50 mass. % Is preferred. By setting it to the lower limit or higher, the strength of the gel electrolyte is further improved, and by setting it to the upper limit or lower, the lithium ion secondary battery shows more excellent battery performance.

The organic solvent for dilution is preferably one that can sufficiently dissolve or disperse any of the components. Specifically, nitrile compounds such as acetonitrile; ether compounds such as tetrahydrofuran: amide compounds such as dimethylformamide It can be illustrated.
The organic solvent for dilution may be used individually by 1 type, and may use 2 or more types together. When two or more kinds are used in combination, the combination and ratio may be appropriately selected according to the purpose.

  The gel electrolyte is preferably one that does not exhibit fluidity in an environment of 40 ° C. or lower where a lithium ion secondary battery is normally used.

The blending method of each component at the time of manufacturing the gel electrolyte may be the same as in the case of the electrolytic solution.
The drying method for removing the diluting organic solvent is not particularly limited, and for example, a known method using a dry box, a vacuum desiccator, a vacuum dryer or the like may be applied.

  As the solid electrolyte, a composition obtained by blending (A) a lithium carboxylate, (B) boron trifluoride and / or boron trifluoride complex, an organic solvent for dilution, and (D) a matrix polymer. And (E) a composition obtained by blending a lithium carboxylate-boron trifluoride complex, an organic solvent for dilution, and (D) a matrix polymer, the organic solvent for dilution is removed by drying. And may be formed by blending arbitrary components in the first and second electrolytic solutions as necessary. Here, (A) carboxylic acid lithium salt, (B) boron trifluoride and / or boron trifluoride complex, (E) carboxylic acid lithium salt-boron trifluoride complex, and (C) organic solvent are any Are the same as those in the first electrolyte solution, and the organic solvent for dilution and (D) the matrix polymer are the same as those in the gel electrolyte.

  The solid electrolyte may be molded into a desired shape using a mold.

  In the solid electrolyte, the blending amount of the (D) matrix polymer is not particularly limited, and may be appropriately adjusted according to the type, but the blending amount of the (D) matrix polymer in the total amount of blending components is 2 to 65 mass. % Is preferred. By setting it to the lower limit value or more, the strength of the solid electrolyte (electrolyte membrane) is further improved, and by setting the upper limit value or less, the lithium ion secondary battery shows more excellent battery performance.

The blending method of each component during the production of the solid electrolyte may be the same as in the case of the electrolytic solution.
The drying method for removing the diluting organic solvent may be the same as that for the gel electrolyte.

  The shape of the lithium ion secondary battery is not particularly limited, and can be adjusted to various shapes such as a cylindrical shape, a square shape, a coin shape, and a sheet shape.

  What is necessary is just to manufacture the said lithium ion secondary battery according to a well-known method using the said electrolyte solution, a gel electrolyte, or a solid electrolyte, and an electrode, for example in a glove box or dry air atmosphere.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples.

The chemical substances used in this example are shown below.
Transition metal chalcogenide Molybdenum sulfide (IV) (MoS ₂ ) (Aldrich)
・ Conductive auxiliary agent Acetylene black (manufactured by Denki Kagaku Kogyo)
・ (A) Lithium carboxylate Lithium oxalate (Aldrich)
・ (B) Boron trifluoride complex Boron trifluoride diethyl ether complex (BF ₃ · O (C ₂ H ₅ ) ₂ ) (manufactured by Aldrich)
Organic solvent ethylene carbonate (hereinafter abbreviated as “EC”) (manufactured by Kishida Chemical Co., Ltd.)
Dimethyl carbonate (hereinafter abbreviated as “DMC”) (manufactured by Kishida Chemical Co., Ltd.)
・ Others Lithium hydroxide ・ Monohydrate (LiOH ・ H ₂ O) (Aldrich)
Lithium hexafluorophosphate (LiPF ₆ ) (Kishida Chemical Co., Ltd.)

<Manufacture of lithium ion secondary batteries>
[Example 1]
(Manufacture of composites)
A silicon scrap wafer (manufactured by Shin-Etsu Semiconductor Co., Ltd.) (150 g) and φ20 mm zirconia balls were put into a dedicated zirconia container, and the silicon scrap wafer was coarsely pulverized with a planetary ball mill (P-6: FRITSCH) at 400 rpm for 30 minutes.
The obtained coarsely pulverized silicon (100 g), 2-propanol (120 g), and φ1 mm zirconia beads are put into a dedicated zirconia container, and the coarsely pulverized silicon is pulverized with a planetary ball mill (P-6: FRITSCH) at 400 rpm for 60 minutes. Then, a 2-propanol dispersion of fine powder silicon having an average particle diameter of about 150 nm was obtained.
The obtained 2-propanol dispersion of fine powder silicon was subjected to separation and recovery by a centrifuge, and a 2-propanol wet cake (solid content 66 mass%) of fine powder silicon was obtained.
Water (35 g) and ethanol (5 g) were added to the obtained fine powder silicon wet cake (2.4 g, 1.6 g as fine powder silicon), and molybdenum (IV) sulfide (MoS ₂ ) as a transition metal chalcogenide. ) (0.4 g) was added and dispersed with vigorous stirring at 25 ° C. for 24 hours using a magnetic stirrer. Table 1 shows the blending amount of each component other than the solvent and the ratio (blending ratio) of the blending amount of each component in the total blending amount of the components other than the solvent. In Table 1, for example, “MoS ₂ 0.4 g (20% by mass)” means that the compounding amount of MoS ₂ is 0.4 g and the compounding ratio is 20% by mass.
The obtained dispersion was dried in an oven at 70 ° C. to remove the liquid component to obtain a dried product.
Put the total amount of the dried product, 2-propanol (2g) and φ1mm zirconia beads in a special zirconia container, and grind the dried product in a planetary ball mill (P-6: FRITSCH) at 400 rpm for 60 minutes. Then, a 2-propanol dispersion of a fine powdery composite (1) having an average particle diameter of about 150 nm was obtained.

(Manufacture of negative electrode materials)
Lithium hydroxide monohydrate (1.63 g) was weighed into a bottle, and water (7 g) was added thereto and mixed for 1 hour. And 35 mass% polyacrylic acid aqueous solution (PAA aqueous solution, the product made by Aldrich) (3.5g) is added to LiOH aqueous solution of all obtained, and it stirs for 24 hours, Polyacrylic acid lithium (PAALi) is used as a binder. A PAALi aqueous solution containing 20% by mass was obtained.
The obtained PAALi aqueous solution (1.5 g, 0.3 g as PAALi), 2-propanol dispersion of the above composite (1) (1.5 g as composite (1)), acetylene black (0 .2 g) is weighed into each container, and water is further added thereto, and the ratio of the total blending amount of the blending components (PAALi, composite (1) and acetylene black) other than the solvent in the total amount of the blending components is It adjusted so that it might become 20 mass%.
Next, the ingredients were mixed for 3 minutes at 25 ° C. using a rotating / revolving mixer (“ARE-250” manufactured by Shinky Corporation), and then dispersed for 5 minutes using a homogenizer (“VCX-130PB” manufactured by Tokyo Rika Kikai Co., Ltd.). Furthermore, the slurry-like negative electrode material (1) is obtained by stirring at 25 ° C. for 1 minute using a rotation / revolution mixer (“ARE-250” manufactured by Sinky) and then degassing at 25 ° C. for 1 minute. Obtained.
Table 2 shows the blending amount of each component other than the solvent in the obtained negative electrode material (1) and the ratio (blending ratio) of the blending amount of each component in the total blending amount of the components other than the solvent. In Table 2, for example, “acetylene black 0.3 g (15 mass%)” means that the compounding amount of acetylene black is 0.3 g and the compounding ratio is 15 mass%. “-” Means that the component is not blended. The “total blending amount of components other than the solvent” means the total blending amount of the composite, the conductive additive and the binder in Examples 1 to 3, and in Comparative Examples 1 and 2, silicon and transition metal chalcogenide. , And means the total amount of conductive assistant and binder.

(Manufacture of negative electrode)
The obtained negative electrode material (1) was used on a current collector made of copper foil with a thickness of 18 μm using a mini coater (“MC20” manufactured by Hosensha) so that the thickness after drying was 30 μm. The negative electrode material (1) was applied and dried for 2 hours using a 50 ° C. hot plate, and further vacuum dried for 24 hours at 100 ° C. using a vacuum dryer.
Next, the dried negative electrode material (1) on the current collector was pressed at a pressure of 1500 N using a roll press machine (manufactured by Tester Sangyo Co., Ltd.), and then heated at 100 ° C. in a glove box drying furnace. By drying for a time, the negative electrode (1) in which the negative electrode active material layer was formed on the current collector was obtained.

(Manufacture of electrolyte)
Lithium oxalate (0.153 g), boron trifluoride diethyl ether complex (0.426 g), and a mixed solvent of EC and DMC (2.42 g) as an organic solvent (EC: DMC = 30: 70 (volume ratio)) Was weighed into a sample bottle and mixed at 25 ° C. so that the concentration of lithium atoms was 1.0 mol / kg, to obtain an electrolyte solution (1) which is a non-aqueous electrolyte solution.

  Lithium hexafluorophosphate (0.455 g) and a mixed solvent of EC and DMC (2.545 g) (EC: DMC = 30: 70 (volume ratio)) as an organic solvent were weighed into a sample bottle, By mixing at 25 ° C. so that the concentration becomes 1.0 mol / kg, an electrolytic solution (2) which is a nonaqueous electrolytic solution was obtained.

(Manufacture of lithium ion secondary batteries)
The negative electrode obtained above and a commercially available ternary positive electrode (manufactured by Hosensha Co., Ltd.) were each punched into a disk shape having a diameter of 16 mm. Further, a separator made of glass fiber was used as a separator, and this was punched into a disk shape having a diameter of 17 mm. The obtained positive electrode, separator, and negative electrode were laminated in this order in a battery container (CR2032) made of SUS, and the electrolytic solution (1) obtained above was impregnated into the separator, the negative electrode, and the positive electrode. A lithium-ion secondary battery (1) -1, which is a coin-type cell, was manufactured by placing a SUS plate (thickness 1.2 mm, diameter 16 mm) and covering it.

  Moreover, it replaced with electrolyte solution (1), and the lithium ion secondary battery (1) -2 which is a coin type cell by the method similar to the above except having used electrolyte solution (2) obtained above. Manufactured.

[Examples 2-3]
The negative electrode materials (2) to (3) and the negative electrodes (2) to (3) were prepared in the same manner as in Example 1 except that the compounding amounts of the respective compounding components at the time of producing the composite were as shown in Table 1. ), And lithium ion secondary batteries (2) -1 to (3) -1 and (2) -2 to (3) -2. Table 3 shows the correspondence from the negative electrode material to the lithium ion secondary battery.

[Comparative Example 1]
The same as in Example 1 except that silicon (1.5 g) was blended in place of the 2-propanol dispersion of the composite (1) (1.5 g as the composite (1)) during the production of the negative electrode material. The negative electrode material (R1), the negative electrode (R1), and the lithium ion secondary batteries (R1) -1 and (R1) -2 were manufactured by the method.

[Reference Example 1]
At the time of production of the negative electrode material, silicon (1.2 g) and molybdenum sulfide (IV) (0.3 g) were blended in place of the 2-propanol dispersion of the composite (1) (1.5 g as the composite (1)) A negative electrode material (0), a negative electrode (0), and lithium ion secondary batteries (0) -1 and (0) -2 were produced in the same manner as in Example 1 except that.

<Evaluation of charge / discharge characteristics of lithium ion secondary battery>
The lithium ion secondary battery obtained above was charged at a constant current and constant voltage of 0.2 C at 25 ° C. until the current value converged to 0.1 C with an upper limit voltage of 4.2 V. Constant current discharge was performed to 2.0V. Thereafter, the charge / discharge cycle was repeated in the same manner at a charge / discharge current of 1C, and the capacity retention rate at 50 cycles ((discharge capacity at the 50th cycle (mAh) / discharge capacity at the 1st cycle (mAh)) × 100) (%) was calculated. The results are shown in Table 3.

  As is clear from the above results, the lithium ion secondary batteries of Examples 1 to 3 using the composite (1) in the negative electrode material are the same as those in Comparative Example 1 using silicon instead of the composite (1) in the negative electrode material. The capacity retention rate was higher than that of the lithium ion secondary battery, and the cycle characteristics were excellent. The lithium ion secondary battery of Reference Example 1 that uses silicon and a transition metal chalcogenide instead of the composite (1) in the negative electrode material also has a higher capacity retention rate and cycle characteristics than the lithium ion secondary battery of Comparative Example 1. It was excellent. In any of Examples 1 to 3 and Reference Example 1, the capacity retention rate was higher when the electrolytic solution (1) was used than when the electrolytic solution (2) was used.

  The present invention can be used in the field of lithium ion secondary batteries.

Claims (8)

  One or both of silicon and silicon monoxide, and a transition metal chalcogenide dispersed in the presence of a solvent, a solid content of the dispersion, a conductive auxiliary agent, and a binder are blended. A negative electrode material for a lithium ion secondary battery.   The negative electrode material for a lithium ion secondary battery according to claim 1, wherein the transition metal chalcogenide is a sulfide of a transition metal.   3. The negative electrode material for a lithium ion secondary battery according to claim 1, wherein the transition metal chalcogenide is a chalcogenide of molybdenum, copper, tungsten, or titanium.   The said transition metal chalcogenide is molybdenum sulfide (IV), The negative electrode material for lithium ion secondary batteries as described in any one of Claims 1-3 characterized by the above-mentioned.   A lithium ion secondary battery comprising a negative electrode active material layer formed using the negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 4 on a current collector. Negative electrode. The negative electrode material for a lithium ion secondary battery is a liquid composition in which at least one of the solvent of the dispersion and a different solvent is blended,
The negative electrode for a lithium ion secondary battery according to claim 5, wherein the negative electrode active material layer is formed by coating and drying the liquid composition.   A lithium ion secondary battery comprising the negative electrode for a lithium ion secondary battery according to claim 5 or 6.   (A) lithium carboxylate and (B) boron trifluoride and / or boron trifluoride complex, or (E) lithium carboxylate-boron trifluoride complex, and (C) an organic solvent are blended. The lithium ion secondary battery according to claim 7, comprising: