WO2020067108A1

WO2020067108A1 - Composition for negative electrodes of all-solid-state secondary batteries, negative electrode sheet for all-solid-state secondary batteries, all-solid-state secondary battery, method for producing negative electrode sheet for all-solid-state secondary batteries, and method for producing all-solid-state secondary battery

Info

Publication number: WO2020067108A1
Application number: PCT/JP2019/037485
Authority: WO
Inventors: 陽串田; 智則三村; 宏顕望月
Original assignee: 富士フイルム株式会社
Priority date: 2018-09-27
Filing date: 2019-09-25
Publication date: 2020-04-02
Also published as: JPWO2020067108A1

Abstract

The present invention provides a composition for negative electrodes of all-solid-state secondary batteries, which contains an inorganic solid electrolyte, a binder that is composed of a polymer, a negative electrode active material, and a dispersion medium. This composition for negative electrodes is configured such that the polymer contains a polymer that has a specific bond such as a urethane bond in the main chain, while having a constituent which has a side chain containing a specific group such as a carbonyl group in a chain structure site that is at a distance of 4 atoms or more from the atoms that constitute the main chain. The present invention also provides: a negative electrode sheet for all-solid-state secondary batteries, which uses this solid electrolyte composition; an all-solid-state secondary battery; a method for producing a negative electrode sheet for all-solid-state secondary batteries; and a method for producing an all-solid-state secondary battery.

Description

Composition for negative electrode of all-solid secondary battery, negative electrode sheet and all-solid secondary battery for all-solid secondary battery, and method for producing negative-electrode sheet for all-solid secondary battery and all-solid secondary battery

The present invention relates to a composition for an anode of an all-solid secondary battery, an anode sheet for an all-solid secondary battery and an all-solid secondary battery, and a method for producing an anode sheet for an all-solid secondary battery and an all-solid secondary battery. .

(4) In the all-solid secondary battery, the negative electrode, the electrolyte, and the positive electrode are all made of a solid, and can greatly improve safety and reliability, which are issues of a battery using an organic electrolyte. In addition, an inorganic solid electrolyte used for a solid electrolyte layer or the like of an all-solid secondary battery has been shown to have a high ionic conductivity approaching that of an organic electrolyte, and is expected as a promising electrolyte. Furthermore, it is said that the all-solid-state secondary battery can have a long life. Therefore, research and development of all-solid-state secondary batteries have been actively conducted.

(4) The all-solid-state secondary battery can have a structure in which the electrodes and the solid electrolyte are directly arranged side by side and arranged in series, so that high energy density can be achieved. In recent years, development and commercialization of electric vehicles have been rapidly progressing in consideration of environmental issues, and all-solid-state batteries are required to have higher energy density. When the constituent layers of an all solid state secondary battery are laminated, it is usual to perform pressure bonding in order to secure adhesion between the layers. At this time, if the strength of the constituent layer (the binding force between the solid particles forming the constituent layer) is not sufficient, defects (cracks, chips or breaks, or interface peeling between the solid particles (poor contact)) may occur in the constituent layer. Occur.

As a technique for improving the strength of the constituent layer, a material using a binder for binding solid particles such as an inorganic solid electrolyte has been studied. For example, Patent Document 1 discloses that a polymer (a (meth) acrylic polymer as a suitable polymer) having a macromonomer having a number average molecular weight of 1,000 or more as a side chain component has an average particle size of 10 nm or more, A solid electrolyte composition containing 000 nm or less binder particles, an inorganic solid electrolyte, and a dispersion medium is described.
Patent Document 2 describes a solid electrolyte composition containing an inorganic solid electrolyte, polymer particles composed of various organic polymers, and a specific dispersion medium.

JP 2015-88486 A JP 2016-139511 A

However, since the binder does not usually exhibit ionic conductivity, if the content of the binder in the above material is too large, the battery resistance increases (the ionic conductivity decreases) and the battery performance decreases. Therefore, when a binder is used, it is required to achieve both a reduction in battery resistance and a suppression of the occurrence of the defect.
By the way, the defects of the constituent layers are generated not only when the all-solid secondary battery is manufactured (when the constituent layers are pressed and pressed), but also when the all-solid secondary battery is used (charge / discharge). This is because, when the all-solid secondary battery is charged and discharged, the active material layer contracts and expands, and the film strength (the binding force between the solid particles) gradually decreases. The change in volume due to the contraction and expansion is large in the negative electrode active material layer, and defects are likely to occur in the negative electrode active material layer.
Furthermore, in recent years, with the aim of increasing the battery capacity of the all-solid secondary battery and extending the driving time, a negative electrode active material capable of absorbing more Li ions than a carbon-based material and capable of being alloyed with lithium (for example, Application of Si) is being considered. This negative electrode active material usually has a larger degree of contraction and expansion associated with charging and discharging of the all-solid secondary battery than conventional carbon-based materials. Therefore, when such a negative electrode active material is used, it is required to further increase the strength of the negative electrode active material layer.

The present invention provides a negative electrode composition that can achieve a high level of suppression of resistance rise and improvement in film strength of the obtained negative electrode active material layer by using as a material constituting the negative electrode active material layer of an all solid state secondary battery. The task is to provide things. Further, the present invention provides a method for producing an all-solid secondary battery negative electrode sheet and an all-solid secondary battery, and an all-solid secondary battery negative electrode sheet and an all-solid secondary battery using the solid electrolyte composition. The task is to provide.

The present inventors have made various studies and found that a binder formed of a polymer having a main chain containing a specific bond and a component having a side chain containing a specific group at a specific position is made of an inorganic material. A solid electrolyte, a negative electrode composition prepared in combination with a negative electrode active material and a dispersion medium can form a negative electrode active material layer in which solid particles are firmly bound while suppressing an increase in interface resistance between solid particles, Was found. Furthermore, they have found that an all-solid secondary battery provided with this negative electrode active material layer exhibits high ionic conductivity and can maintain a high discharge capacity even after repeated charging and discharging. The present invention has been further studied based on these findings, and has been completed.

That is, the above problem was solved by the following means.
<1> An all-solid secondary containing an inorganic solid electrolyte having ion conductivity of a metal belonging to

Group

1 or 2 of the periodic table, a binder made of a polymer, a negative electrode active material, and a dispersion medium. A composition for a negative electrode of a battery,
The polymer has at least one bond selected from the group consisting of an amide bond, a urea bond and a urethane bond in the main chain, and
The following conditions A and B:
[Condition A] At least one group selected from the group consisting of a carbonyl group, a thiocarbonyl group and a phosphoryl group is provided in a chain structure at least four atoms away from the atoms constituting the main chain. [Condition B] A composition for a negative electrode, comprising a polymer having a constituent component having a side chain that is not bonded to a hydroxy group.
<2> The composition for a negative electrode according to <1>, wherein the content of the above constituent components in the polymer is 5 to 40% by mass.
<3> In the above components, the proportion of the total weight ^{W G} of the base relative to the total weight ^{W S} of the chain structure portion ^{^[W} G / W ^S] is 0.05 or more, according to <1> or <2> A composition for a negative electrode.
<4> The composition for a negative electrode according to any one of <1> to <3>, wherein the negative electrode active material is an active material that can be alloyed with lithium.
<5> The negative electrode composition according to <4>, wherein the active material that can be alloyed with lithium is a silicon-based negative electrode active material containing a Si element as a constituent element.

<6> The negative electrode composition according to any one of <1> to <5>, wherein the side chain has a partial structure represented by any of the following formulas (I) to (III).

In the formula, L ¹ to L ⁴ represent a linking group, and R ¹ and R ² represent a substituent.

<7> The composition for a negative electrode according to any one of <1> to <6>, wherein the binder is dispersed in a dispersion medium.
<8> The composition for a negative electrode according to any one of <1> to <7>, further comprising a conductive additive.
<9> The composition for a negative electrode according to any one of <1> to <8>, wherein the inorganic solid electrolyte is a sulfide-based solid electrolyte.
<10> A negative electrode sheet for an all-solid secondary battery having a negative electrode active material layer composed of the composition for a negative electrode according to any one of the above <1> to <9>.
<11> An all-solid secondary battery including a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order,
An all-solid secondary battery in which the negative electrode active material layer is a negative electrode active material layer composed of the composition for a negative electrode according to any one of <1> to <9>.
<12> A method for producing a negative electrode sheet for an all-solid secondary battery, wherein the negative electrode composition according to any one of <1> to <9> is formed.
<13> A method for manufacturing an all-solid secondary battery, which manufactures an all-solid secondary battery via the manufacturing method according to <12>.

ADVANTAGE OF THE INVENTION The composition for negative electrodes of this invention can form the negative electrode active material layer which suppressed the increase in resistance and improved the film | membrane strength at a high level. The negative electrode composition of the present invention, and the negative electrode sheet for an all-solid secondary battery of the present invention provided with a negative electrode active material layer formed of the negative electrode composition of the present invention are used for the negative electrode active material layer of the all-solid secondary battery. By using the material as a forming material, it is possible to provide the all-solid secondary battery with a reduction in battery resistance and a property capable of maintaining a high discharge capacity. The all-solid-state secondary battery of the present invention exhibits low battery resistance and characteristics capable of maintaining a high discharge capacity. Further, the method for producing an all-solid secondary battery negative electrode sheet and the all-solid secondary battery of the present invention produces the all-solid secondary battery negative electrode sheet and the all-solid secondary battery of the present invention exhibiting the above-described excellent characteristics. be able to.
The above and other features and advantages of the present invention will become more apparent from the following description, appropriately referring to the accompanying drawings.

FIG. 1 is a longitudinal sectional view schematically illustrating an all solid state secondary battery according to a preferred embodiment of the present invention. It is a longitudinal cross-sectional view which shows typically the test body for ion conductivity measurement produced in the Example.

In this specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit.
In this specification, when simply described as “acryl” or “(meth) acryl”, it means acryl and / or methacryl.
In the present specification, the expression of a compound (for example, when the compound is referred to as a suffix) is used to include the compound itself, its salt, and its ion. Further, it is meant to include a derivative partially changed by introducing a substituent within a range in which a desired effect is exhibited.
In the present specification, a substituent, a linking group, and the like (hereinafter, referred to as a substituent, etc.) which is not specified as substituted or unsubstituted means that the group may have an appropriate substituent. Therefore, in the present specification, even when simply referred to as a YYY group, the YYY group also includes an embodiment having a substituent in addition to an embodiment having no substituent. This is synonymous with a compound for which no substitution or no substitution is specified. Preferred substituents are not particularly limited, for example, the substituent which may take as R ^M2 or R ¹ described later.
In the present specification, when there are a plurality of substituents and the like indicated by a specific symbol, or when defining a plurality of substituents simultaneously or alternatively, each substituent and the like may be the same or different from each other Means good. Further, even when not otherwise specified, when a plurality of substituents and the like are adjacent to each other, it means that they may be connected to each other or condensed to form a ring.

In the present invention, a composition containing an inorganic solid electrolyte is referred to as a solid electrolyte composition or an inorganic solid electrolyte-containing composition, and when a composition containing a negative electrode active material or a positive electrode active material is further distinguished from a solid electrolyte composition. Are respectively referred to as a negative electrode composition and a positive electrode composition.
In the present invention, the negative electrode active material and the positive electrode active material may be collectively referred to as an active material, and the negative electrode composition and the positive electrode composition may be collectively referred to as an electrode composition.

[Composition for negative electrode]
The composition for a negative electrode of the present invention contains an inorganic solid electrolyte, a binder made of a polymer, a dispersion medium, and a negative electrode active material. The polymer forming the binder includes a polymer having at least one bond selected from the group consisting of an amide bond, a urea bond and a urethane bond in the main chain. Further, this polymer has a component having a side chain satisfying the following conditions A and B.
Condition A: at least one group selected from the group consisting of a carbonyl group, a thiocarbonyl group, and a phosphoryl group (> P (ＯO) —) is provided on a chain structure portion at least four atoms away from the atoms constituting the main chain. Have.
Condition B: none of the carbonyl group, thiocarbonyl group and phosphoryl group are bonded to the hydroxy group. That is, the carbonyl group, thiocarbonyl group, and phosphoryl group do not form a carboxy group, thiocarboxy group, or hydroxyphosphoryl, respectively.

This polymer binds solid particles (for example, an inorganic solid electrolyte, a negative electrode active material, and a negative electrode active material) to each other in the negative electrode composition and the negative electrode active material layer formed of the negative electrode composition, and further collects the particles. It functions as a binding agent (binder) for binding the electric body and the solid particles.
It is considered that when the composition for a negative electrode of the present invention having the above composition is used as a negative electrode active material layer, an increase in interface resistance can be suppressed and solid particles can be firmly bound. As a result, the negative electrode sheet for an all-solid secondary battery and the all-solid secondary battery provided with the negative electrode active material layer formed using the negative electrode composition of the present invention have low battery resistance (high ionic conductivity) and sufficient charge. The characteristics (excellent cycle characteristics) that can maintain a high discharge capacity even after repeated discharges. Although the details of the reason are not yet clear, it is considered as follows.

That is, since the main chain of the polymer is configured to include the specific bond described above, the specific bond forms a hydrogen bond (interaction), whereby the polymers are strongly connected to each other (intramolecular or molecular). (Establishment or integration of a polymer network by hydrogen bonding between them), and the film strength of the negative electrode active material layer can be enhanced. In addition, this polymer contains a component having a specific group such as a carbonyl group in a chain structure of a side chain. Therefore, the specific group interacts with a functional group (for example, a silanol group or a siloxy group) present on the surface of the negative electrode active material, and further on the surface of solid particles such as an inorganic solid electrolyte, so that the above-mentioned polymer becomes negative electrode active material. It exhibits high adsorption power to solid particles such as substances. As a result, the solid particles can be firmly bound together, and furthermore, the solid particles and the negative electrode current collector can be firmly bound. Thus, not only during pressure bonding of the negative electrode active material layer and the like but also during charging and discharging of the all-solid-state secondary battery, resistance to stress (and stress concentration) acting on the negative electrode active material layer is exhibited. Generation of defects in the material layer is suppressed. This defect generation can be effectively suppressed even when the negative electrode active material layer contains a negative electrode active material that can be alloyed with lithium.
In the present invention, the interaction between the specific group of the polymer and the solid particle may be a chemical interaction or a physical interaction, and is not unique due to the functional group present on the surface of the solid particle. , Hydrogen bond, acid-base ionic bond, covalent bond, aromatic ring π-π interaction, hydrophobic-hydrophobic interaction, and the like.

{Circle around (2)} The binder made of the polymer is adsorbed on the solid particles by the above-mentioned group located at a specific position away from the main chain, and partially covers the surface of the solid particles, not the whole. Therefore, the solid particles can directly contact each other, and an ion conduction path and an electron conduction path are constructed. The construction of the conduction path and the strong binding force of the solid particles by the polymer can suppress an increase in (battery) resistance of the negative electrode active material layer and the all-solid secondary battery.

From these, it is considered that the negative electrode composition of the present invention can form a high-strength negative electrode active material layer in which solid particles such as a negative electrode active material are firmly bound while suppressing an increase in interface resistance between solid particles. Can be The composition for a negative electrode of the present invention exhibiting such a function and effect can impart high ionic conductivity and excellent cycle characteristics to an all-solid secondary battery, and can be used as a negative electrode sheet or an all-solid secondary battery for an all-solid secondary battery. Can be preferably used as a material for forming the negative electrode active material layer.

In the composition for a negative electrode of the present invention, the mixing mode of the inorganic solid electrolyte, the binder, the negative electrode active material, and the dispersion medium is not particularly limited, but at least, from a polymer having a constituent component having a side chain satisfying the above conditions A and B. The binder is preferably a slurry in which the inorganic solid electrolyte and the negative electrode active material are dispersed in a dispersion medium.

The composition for a negative electrode of the present invention is not particularly limited, but preferably has a water content (also referred to as a water content) of 500 ppm or less, more preferably 200 ppm or less, further preferably 100 ppm or less. It is particularly preferably at most 50 ppm. When the water content of the negative electrode composition is low, the deterioration of the inorganic solid electrolyte can be suppressed. The water content indicates the amount of water (mass ratio based on the composition for the negative electrode) contained in the composition for the negative electrode. Specifically, the water content is filtered through a 0.02 μm membrane filter, and measured by Karl Fischer titration. The measured value.

Hereinafter, components contained in the composition for a negative electrode of the present invention and components that may be contained will be described.

<Inorganic solid electrolyte>
The composition for a negative electrode of the present invention contains an inorganic solid electrolyte.
In the present invention, the inorganic solid electrolyte is an inorganic solid electrolyte, and the solid electrolyte is a solid electrolyte in which ions can move inside. Since it does not contain an organic substance as a main ion conductive material, an organic solid electrolyte (a polymer electrolyte represented by polyethylene oxide (PEO), etc .; an organic represented by lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), etc.) Electrolyte salt). Further, since the inorganic solid electrolyte is a solid in a steady state, it is not usually dissociated or released into cations and anions. In this respect, the electrolyte solution or the inorganic electrolyte salt (LiPF ₆ , LiBF ₄ , lithium bis (fluorosulfonyl) imide (LiFSI), LiCl, etc.) dissociated or released into cations and anions in the polymer is clearly distinguished. Is done. The inorganic solid electrolyte is not particularly limited as long as it has ion conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and generally does not have electron conductivity. When the all solid state secondary battery of the present invention is a lithium ion battery, the inorganic solid electrolyte preferably has lithium ion ionic conductivity.

As the inorganic solid electrolyte, a solid electrolyte material usually used for an all-solid secondary battery can be appropriately selected and used. Examples of the inorganic solid electrolyte include (i) a sulfide-based inorganic solid electrolyte, (ii) an oxide-based inorganic solid electrolyte, (iii) a halide-based inorganic solid electrolyte, and (iv) a hydride-based solid electrolyte. In the present invention, a sulfide-based inorganic solid electrolyte is preferably used from the viewpoint that a better interface can be formed between the active material and the inorganic solid electrolyte.

(I) Sulfide-based inorganic solid electrolyte The sulfide-based inorganic solid electrolyte contains a sulfur atom, has ionic conductivity of a metal belonging to

Group

1 or 2 of the periodic table, and has electronic insulation. Those having properties are preferred. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S, and P as elements and has lithium ion conductivity, but depending on the purpose or case, other than Li, S, and P, It may contain an element.

Examples of the sulfide-based inorganic solid electrolyte include a lithium ion conductive inorganic solid electrolyte satisfying a composition represented by the following formula (1).

_{_{_{_{L a1 M b1 P c1 S d1}}}} A e1 (1)

In the formula, L represents an element selected from Li, Na and K, and Li is preferable. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al and Ge. A represents an element selected from I, Br, Cl and F. a1 to e1 indicate the composition ratio of each element, and a1: b1: c1: d1: e1 satisfies 1 to 12: 0 to 5: 1: 2 to 12: 0 to 10. a1 is preferably 1 to 9, and more preferably 1.5 to 7.5. b1 is preferably 0 to 3, more preferably 0 to 1. d1 is preferably from 2.5 to 10, and more preferably from 3.0 to 8.5. e1 is preferably from 0 to 5, more preferably from 0 to 3.

組成 The composition ratio of each element can be controlled by adjusting the compounding amount of the raw material compound when producing the sulfide-based inorganic solid electrolyte as described below.

The sulfide-based inorganic solid electrolyte may be non-crystalline (glass) or crystallized (glass-ceramic), or may be partially crystallized. For example, Li-PS-based glass containing Li, P and S, or Li-PS-based glass ceramic containing Li, P and S can be used.
Examples of the sulfide-based inorganic solid electrolyte include lithium sulfide (Li ₂ S), phosphorus sulfide (for example, diphosphorus pentasulfide (P ₂ S ₅ )), elemental phosphorus, elemental sulfur, sodium sulfide, hydrogen sulfide, and lithium halide (for example, LiI, LiBr, LiCl) and at least two or more of sulfides (for example, SiS ₂ , SnS, GeS ₂ ) of the element represented by M can be produced.

In Li-P-S based glass and Li-P-S based glass ceramics, the ratio of Li ₂ S and _P 2 _{S 5} _is, Li 2 _S: at a molar ratio of P 2 _{S 5,} preferably 60: 40 ~ 90:10, more preferably 68:32 to 78:22. By setting the ratio of Li ₂ S and P ₂ S ₅ to this range, the lithium ion conductivity can be increased. Specifically, the lithium ion conductivity can be preferably 1 × 10 ⁻⁴ S / cm or more, more preferably 1 × 10 ⁻³ S / cm or more. Although there is no particular upper limit, it is practical that it is 1 × 10 ⁻¹ S / cm or less.

As examples of specific sulfide-based inorganic solid electrolytes, combinations of raw materials are shown below. For example, Li ₂ S—P ₂ S ₅ , Li ₂ S—P ₂ S ₅ —LiCl, Li ₂ S—P ₂ S ₅ —H ₂ S, Li ₂ S—P ₂ S ₅ —H ₂ S—LiCl, Li ₂ S—LiI—P ₂ S ₅ , Li ₂ S—LiI—Li ₂ O—P ₂ S ₅ , Li ₂ S—LiBr—P ₂ S ₅ , Li ₂ S—Li ₂ O—P ₂ S ₅ , Li ₂ S—Li ₃ PO ₄ —P ₂ S ₅ , Li ₂ SP—P ₂ S ₅ —P ₂ O ₅ , Li ₂ SP—P ₂ S ₅ —SiS ₂ , Li ₂ SP—P ₂ S ₅ —SiS _{_{_{_{2 -LiCl, Li 2 S-P}}}} 2 S 5 -SnS, Li 2 S-P 2 S 5 -Al 2 S 3, Li 2 S-GeS 2, Li 2 S-GeS 2 -ZnS, Li 2 S-Ga _{_{_{_{2 S 3, Li 2 S-}}}} GeS 2 -Ga 2 S 3, Li 2 S-GeS 2 -P 2 S 5 _{_{_{_{Li 2 S-GeS 2 -Sb 2}}}} S 5, Li 2 S-GeS 2 -Al 2 S 3, Li 2 S-SiS 2, Li 2 S-SiS 5, Li 2 S-Al 2 S 3, Li 2 S —SiS ₂ —Al ₂ S ₃ , Li ₂ S—SiS ₂ —P ₂ S ₅ , Li ₂ S—SiS ₂ —P ₂ S ₅ —LiI, Li ₂ S—SiS ₂ —LiI, Li ₂ S—SiS ₂ —Li ₄ SiO ₄ , Li ₂ S—SiS ₂ —Li ₃ PO ₄ , Li ₁₀ GeP ₂ S _{12 and the} like. However, the mixing ratio of each raw material does not matter. As a method for synthesizing a sulfide-based inorganic solid electrolyte material using such a raw material composition, for example, an amorphization method can be mentioned. Examples of the amorphization method include a mechanical milling method, a solution method, and a melt quenching method. This is because processing at normal temperature becomes possible, and the manufacturing process can be simplified.

(Ii) Oxide-based inorganic solid electrolyte The oxide-based inorganic solid electrolyte contains an oxygen atom, has ionic conductivity of a metal belonging to

Group

1 or 2 of the periodic table, and has electronic insulation. Those having properties are preferred.
The oxide-based inorganic solid electrolyte has an ionic conductivity of preferably 1 × 10 ⁻⁶ S / cm or more, more preferably 5 × 10 ⁻⁶ S / cm or more, and more preferably 1 × 10 ⁻⁵ S / cm. / Cm or more is particularly preferable. The upper limit is not particularly limited, but is practically 1 × 10 ⁻¹ S / cm or less.

Specific compounds, for example _Li xa _La ya TiO ₃ [xa satisfies 0.3 ≦ xa ≦ 0.7, ya satisfies 0.3 ≦ ya ≦ 0.7. ] _{_{_{^{(LLT); Li xb La yb}}}} Zr zb M bb mb O nb (M bb is Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, one or more elements selected from In and Sn Xb satisfies 5 ≦ xb ≦ 10, yb satisfies 1 ≦ yb ≦ 4, zb satisfies 1 ≦ zb ≦ 4, mb satisfies 0 ≦ mb ≦ 2, and nb satisfies 5 ≦ nb ≦ 20. _{_{^{_{met);. Li xc B yc M}}}} cc zc O nc (M cc is C, S, Al, Si, Ga, Ge, is .xc is one or more elements selected from in and Sn 0 <xc ≦ 5 , Yc satisfies 0 <yc ≦ 1, zc satisfies 0 <zc ≦ 1, and nc satisfies 0 <nc ≦ 6.); Li _xd (Al, Ga) _yd (Ti, Ge) _zd Si _ad P _md O _nd (xd satisfies 1 ≦ xd ≦ 3, yd Satisfies 0 ≦ yd ≦ 1, zd satisfies 0 ≦ zd ≦ 2, ad satisfies 0 ≦ ad ≦ 1, md satisfies 1 ≦ md ≦ 7, and nd satisfies 3 ≦ nd ≦ 13.) _{^{_{; Li (3-2xe) M ee xe}}} D ee O (xe represents a number of 0 to ^{0.1, M ee} is ^{.D ee} halogen atom or two or more halogen atoms representing a divalent metal atom Li _xf Si _yf O _zf (xf satisfies 1 ≦ xf ≦ 5, yf satisfies 0 <yf ≦ 3, and zf satisfies 1 ≦ zf ≦ 10); Li _xg S _yg O _zg (xg satisfies 1 ≦ xg ≦ 3, yg satisfies 0 <yg ≦ 2, zg satisfies 1 ≦ zg ≦ 10); Li ₃ BO ₃ ; Li ₃ BO ₃ -Li ₂ SO ₄ ; _{_{_{_{Li 2 O-B 2 O 3}}}} -P 2 O 5; Li 2 O-SiO 2 _{_{_{_{Li 6 BaLa 2 Ta 2 O 12}}}} ; Li 3 PO (4-3 / 2w) N w (w is _{w <1); LISICON Li 3.5} Zn 0.25 GeO with (Lithium super ionic conductor) type crystal structure ₄ ; La _0.55 Li _0.35 TiO ₃ having a perovskite crystal structure; LiTi ₂ P ₃ O ₁₂ having a NASICON (Natrium superionic conductor) crystal structure; Li _{1 + xh + yy} (Al, Ga) _xh (Ti, _eG ) ) _2-xh Si _yh P _3-yh O ₁₂ (xh satisfies 0 ≦ xh ≦ 1 and yh satisfies 0 ≦ yh ≦ 1). ); Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ) having a garnet-type crystal structure.
Further, a phosphorus compound containing Li, P and O is also desirable. For example, lithium phosphate (Li ₃ PO ₄ ); LiPON in which a part of oxygen of lithium phosphate is substituted with nitrogen; LiPOD ¹ (D ¹ is preferably Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au).
Further, LiA ¹ ON (A ¹ is at least one element selected from Si, B, Ge, Al, C and Ga) can also be preferably used.

(Iii) Halide-based inorganic solid electrolyte A halide-based inorganic solid electrolyte is generally used and contains a halogen atom and has an ionic conductivity of a metal belonging to

Group

1 or 2 of the periodic table. And a compound having electronic insulating properties.
The halide-based inorganic solid electrolyte is not particularly limited, and examples thereof include compounds such as LiCl, LiBr, LiI, and Li ₃ YBr ₆ and Li ₃ YCl ₆ described in ADVANCED MATERIALS, 2018, _30, 1803075. Among them, Li ₃ YBr ₆ and Li ₃ YCl ₆ are preferable.

(IV) Hydride-based inorganic solid electrolyte A hydride-based inorganic solid electrolyte is generally used, and contains a hydrogen atom and has an ionic conductivity of a metal belonging to

Group

1 or 2 of the periodic table. And a compound having electronic insulating properties.
The hydride-based inorganic solid electrolyte is not particularly limited, and examples thereof include LiBH ₄ , Li ₄ (BH ₄ ) ₃ I, 3LiBH ₄ -LiCl, and the like.

The inorganic solid electrolyte is preferably particles. In this case, the average particle size (volume average particle size) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.1 μm or more. The upper limit is preferably 100 μm or less, more preferably 50 μm or less. The measurement of the average particle size is performed according to the following procedure. The inorganic solid electrolyte particles are diluted with water (heptane in the case of a substance unstable to water) to prepare a 1% by mass dispersion liquid in a 20 mL sample bottle. The dispersion sample after dilution is irradiated with 1 kHz ultrasonic wave for 10 minutes and used immediately after the test. Using this dispersion liquid sample, data was taken 50 times at a temperature of 25 ° C. using a laser diffraction / scattering type particle size distribution analyzer LA-920 (trade name, manufactured by HORIBA) using a quartz cell for measurement. Obtain the volume average particle size. For other detailed conditions and the like, refer to the description of JIS Z 8828: 2013 “Particle Size Analysis-Dynamic Light Scattering Method” as necessary. Five samples are prepared for each level, and the average value is adopted.

The composition for a negative electrode may contain one kind of inorganic solid electrolyte, or may contain two or more kinds.
When the negative electrode active material layer is formed, the total mass (mg) (weight per unit area) of the inorganic solid electrolyte and the negative electrode active material described later per unit area (cm ² ) of the negative electrode active material layer is not particularly limited. . It can be appropriately determined according to the designed battery capacity, for example, 1 to 100 mg / cm ² .

The total content of the inorganic solid electrolyte and the negative electrode active material in the negative electrode composition is 50% by mass or more at a solid content of 100% by mass in terms of dispersibility, reduction of interface resistance, and binding properties. Is preferably 70% by mass or more, and particularly preferably 90% by mass or more. From the same viewpoint, the upper limit is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and particularly preferably 99% by mass or less.
In the present specification, the solid content (solid component) refers to a component that does not disappear by volatilization or evaporation when the composition for a negative electrode is dried at 170 ° C. for 6 hours under a nitrogen atmosphere under a pressure of 1 mmHg. Typically, it refers to components other than the dispersion medium described below.

<Binder>
The binder contained in the composition for a negative electrode of the present invention contains a binder comprising the following polymer.
This polymer has a main chain containing at least one bond selected from the group consisting of an amide bond, a urea bond, and a urethane bond. Further, this polymer has a component having a side chain that satisfies the conditions A and B described later as a component forming the polymer.

において In the present invention, the main chain of the polymer refers to a linear molecular chain in which all other molecular chains constituting the polymer can be regarded as branched or pendant to the main chain. Typically, the longest chain among the molecular chains constituting the polymer is the main chain. However, the functional groups of the polymer terminals are not included in the main chain. The side chain of the polymer refers to a molecular chain other than the main chain, and includes a short molecular chain and a long molecular chain.

(Polymer main chain)
The main chain of the polymer has at least one bond selected from the group consisting of an amide bond, a urea bond, and a urethane bond. These bonds contained in the main chain form hydrogen bonds, thereby contributing to an improvement in the film strength of the negative electrode active material layer as described above. Therefore, the hydrogen bond formed by these bonds may be the above-mentioned bonds or other partial structures of the above-mentioned bond and the main chain. The bond preferably has a hydrogen atom that forms a hydrogen bond (the nitrogen atom of each bond is unsubstituted) in that a hydrogen bond can be formed with each other.

The above-mentioned bond is not particularly limited as long as it is contained in the main chain of the polymer, and may be any of a form included in a structural unit (repeating unit) and / or a form included as a bond connecting different structural units. . Further, the number of the bonds contained in the main chain is not limited to one type, and may be two or more types. In this case, the bonding mode of the main chain is not particularly limited, and the main chain may have two or more types of bonds at random, and may be a segmented main chain of a segment having a specific bond and a segment having another bond. It may be a chain.

The main chain having the above bond is not particularly limited, but is preferably a main chain having at least one segment selected from polyamide, polyurea and polyurethane, and more preferably a main chain made of polyamide, polyurea or polyurethane. Specifically, the main chain having the above-mentioned bond is formed by combining two or more (preferably 2 to 8) components represented by any of the following formulas (I-1) to (I-4). A backbone is preferred. The combination of each component is appropriately selected according to the above-mentioned binding.

In the formula, R ^P1 and R ^P2 each represent a hydrocarbon group or a molecular chain having a mass average molecular weight of 200 to 200,000.
R ^P1 is preferably a hydrocarbon group, more preferably an aromatic hydrocarbon group. R ^P2 is preferably an aliphatic hydrocarbon group or the above-mentioned molecular chain, and more preferably an embodiment containing each of the aliphatic hydrocarbon group and the above-mentioned molecular chain. In this embodiment, the component represented by the formula (I-3) or (I-4) includes a component in which R ^P2 is an aliphatic hydrocarbon group and a component in which R ^P2 is the above-mentioned molecular chain. Contains two of the components.

The hydrocarbon group that can be taken as R ^P1 and R ^P2 is a hydrocarbon group having a mass average molecular weight of less than 200, and includes, for example, an aliphatic or aromatic hydrocarbon group. Examples of the hydrocarbon group include an alkylene group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 and still more preferably 1 to 3), and an arylene group (preferably having 6 to 14 carbon atoms and more preferably 6 to 10). Or a group consisting of a combination thereof. The hydrocarbon group can take as R ^P2, and more preferably an alkylene group, more preferably an alkylene group having 2 to 6 carbon atoms, particularly preferably an alkylene group having 2 or 3 carbon atoms.
The hydrocarbon group that can be taken as R ^P1 and R ^P2 is, for example, a hydrocarbon group represented by the following formula (M2), and an oxygen atom in the group such as N, N′-bis (2-hydroxyethyl) oxamide. , A sulfur atom or a group containing an imino group.

The aliphatic hydrocarbon group is not particularly limited, and may be a hydrogen reduced form of an aromatic hydrocarbon group represented by the following formula (M2), a partial structure (for example, an isophoronyl group) of a known aliphatic diisosonate compound, or the like. Is mentioned.
The aromatic hydrocarbon group is preferably a hydrocarbon group represented by the following formula (M2).

In the formula (M2), X represents a single bond, —CH ₂ —, —C (CH ₃ ) ₂ —, —SO ₂ —, —S—, —CO—, or —O—; In the formula, —CH ₂ — or —O— is preferable, and —CH ₂ — is more preferable. The alkylene group exemplified here may be substituted with a halogen atom (preferably a fluorine atom).
R ^M2 to R ^M5 each represent a hydrogen atom or a substituent, and a hydrogen atom is preferable. The substituents that can be taken as R ^M2 to R ^M5 are not particularly limited. For example, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, —OR ^M6 , —N (R ^M6 ) ₂ , —SR ^M6 (R ^M6 represents a substituent, preferably an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 10 carbon atoms), a halogen atom (eg, a fluorine atom, a chlorine atom, a bromine atom) Is mentioned. —N (R ^M6 ) ₂ is an alkylamino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 6) or an arylamino group (having a carbon number of preferably 6 to 40, and 6 to 20 is preferable) More preferred).

The molecular chain which can be taken as R ^P1 and R ^P2 is preferably a hydrocarbon group, a polyalkylene oxide chain, a polycarbonate chain or a polyester chain, more preferably a hydrocarbon group or a polyalkylene oxide chain, and is preferably a hydrocarbon group or a polyalkylene oxide chain. Ethylene oxide chains or polypropylene oxide chains are more preferred.
The hydrocarbon group is not particularly limited, but preferably has 18 or more, more preferably 30 or more, and still more preferably 50 or more carbon atoms. The upper limit is not particularly limited, and may be, for example, 90. The hydrocarbon chain may have a carbon-carbon unsaturated bond, and may have a ring structure of an aliphatic ring and / or an aromatic ring. That is, the hydrocarbon chain may be a hydrocarbon chain composed of a hydrocarbon group selected from an aliphatic hydrocarbon group and an aromatic hydrocarbon group, and may be a hydrocarbon chain composed of an aliphatic hydrocarbon group. Base chains are preferred. The hydrocarbon chain is preferably an aliphatic saturated hydrocarbon group or aliphatic unsaturated hydrocarbon group or a polymer (preferably an elastomer) that satisfies the above-mentioned number of carbon atoms. Specific examples of the polymer include a diene polymer having a double bond in the main chain and a non-diene polymer having no double bond in the main chain. Examples of the diene polymer include a styrene-butadiene copolymer, a styrene-ethylene-butadiene copolymer, a copolymer of isobutylene and isoprene (preferably butyl rubber (IIR)), a butadiene polymer, an isoprene polymer, and ethylene. -Propylene-diene copolymer and the like. Examples of the non-diene polymer include olefin polymers such as an ethylene-propylene copolymer and a styrene-ethylene-butylene copolymer, and hydrogen reduced products of the diene polymer.

Examples of the polyalkylene oxide chain include a chain composed of a known polyalkylene oxide. The alkyleneoxy group as a constituent component preferably has 1 to 8 carbon atoms, more preferably 1 to 6, and even more preferably 2 or 3 (polyethylene oxide chain or polypropylene oxide chain).
Examples of the polycarbonate chain or the polyester chain include a chain composed of a known polycarbonate or polyester.

When the molecular chain is a polyalkylene oxide chain, a polycarbonate chain or a polyester chain, it preferably has an alkyl group (having preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms) at the terminal.
In the alkyl group contained in the molecular chain, an ether group (—O—), a thioether group (—S—), a carbonyl group (> C ＝ O), an imino group (> NR ^N : ^RN is a hydrogen atom, and has 1 carbon atom) (Alkyl group of 6 to 6 or aryl group of 6 to 10 carbon atoms).
The mass average molecular weight of the molecular chain is preferably 250 or more, more preferably 500 or more, still more preferably 700 or more, and particularly preferably 1,000 or more. The upper limit is preferably 100,000 or less, more preferably 10,000 or less. The mass average molecular weight of the molecular chain is measured for the raw material compound before being incorporated into the main chain of the polymer.

The starting compound (diisocyanate compound) for deriving the component represented by the above formula (I-1) is not particularly limited, and for example, a diisocyanate represented by the formula (M1) described in WO2018 / 020827 Compounds and specific examples thereof are given. The starting compound (such as a carboxylic acid or an acid chloride thereof) for deriving the component represented by the above formula (I-2) is not particularly limited, and for example, a compound represented by the formula ( The compound represented by M1) and specific examples thereof are exemplified.
The raw material compound (diol compound or diamine compound) for deriving the component represented by the above formula (I-3) or (I-4) is not particularly limited, and is described in, for example, International Publication No. WO2018 / 020827. Each of the compounds described above and specific examples thereof are exemplified, and further, dihydroxyoxamide is exemplified.

R ^P1 and R ^P2 may each have a substituent. Examples of the substituent group is not particularly limited, for example, an above substituents can take as R ^M2, also also include groups corresponding to the side chain will be described later.

(Components with side chains)
The polymer forming the binder has a component having a specific side chain described later. This side chain may be incorporated into any component as long as it is a component forming a polymer. For example, this side chain is incorporated into any one of the above formulas (I-1) to (I-4). You may. Above all, it is preferable that it is incorporated in the component represented by the above formula (I-3) or (I-4), and the structure represented by the above formula (I-3) or (I-4) it is more preferred that R ^P2 among components are incorporated in component a hydrocarbon group having aliphatic. When these constituents have a specific side chain, they easily interact with the negative electrode active material.

－ Side chain －
The side chain of the polymer forming the binder satisfies the following conditions A and B.
Condition A: at least one group selected from the group consisting of a carbonyl group, a thiocarbonyl group, and a phosphoryl group (> P (ＯO) —) is provided in a chain structure portion at least four atoms away from atoms constituting the main chain. Have.
Condition B: none of the carbonyl group, thiocarbonyl group and phosphoryl group are bonded to a hydroxy group.

In the condition A, the chain structure part in the side chain is a side chain (a molecular chain composed of a group of atoms bonded in a chain), which is located at a terminal side of the side chain that is at least 4 atoms away from atoms constituting the main chain molecular chain. Refers to the structural part. For example, when the molecular chain of the main chain contains an alkylene group, and the side chain is bonded to a carbon atom constituting the alkylene group (carbon atom forming the main chain), the chain structure part is attached to the carbon atom forming the main chain. A portion where the number of connected atoms is 4 or more in the longest molecular chain starting from the bonding atom. However, when the end of the molecular chain is a hydrogen atom, this hydrogen atom is not included in the number of connected atoms.
More specifically, in the component A-1 in Examples described later, the longest molecular chain (−) starts from the carbon atom bonded to the carbon atom forming the main chain molecular chain (ethylene dioxide chain). In a C—S—C—C (tertiary carbon atom) —C (carbonyl carbon atom) —O—C (carbon chain of a methyl group), the number of connected atoms is 4 or more. (C (tertiary carbon atom) -C (carbonyl carbon atom) -OC (carbon atom of methyl group)) becomes the chain structure.

The side chain has at least one group selected from the group consisting of a carbonyl group, a thiocarbonyl group and a phosphoryl group (> P (= O)-) in the above-mentioned chain structure. As a result, a strong interaction with the negative electrode active material occurs in combination with the ease of molecular movement of the side chain.
From the viewpoint of interaction with the negative electrode active material, it is preferable that these groups are incorporated at the end of the above-mentioned chain structure. The group closest to the atoms that make up the molecular chain of the chain is preferably incorporated into a chain structure that is at least 6 atoms away from the atoms that make up the main chain molecular chain, More preferably, it is incorporated. On the other hand, among the above-mentioned groups incorporated in the chain structure, the most terminal group is preferably incorporated within 2 to 4 atoms from the end of the chain structure (excluding the hydrogen atom). More preferably, it is incorporated within 2 or 3 atoms.

The above group contained in the chain structure is preferably a carbonyl group.
The carbonyl group, thiocarbonyl group, and phosphoryl group (> P (（O) —) do not have a hydroxy group as an end of the chain structure (condition B). Further, it is preferable that none of these groups is bonded to a hydrogen atom. That is, these groups are preferably incorporated in the chain structure. Two of the bonds of the phosphoryl group are used for incorporation into the chain structure, and the other one bonds to a substituent other than a hydrogen atom and a hydroxy group. The substituent is not particularly limited, and examples thereof include the following substituents that can be taken as R ¹ and R ² .

The number of the groups included in the chain structure portion may be at least one in one chain structure portion (constituent component), for example, 1 to 10, and 1 to 5 in terms of interaction with the negative electrode active material. Is preferable, and 1-3 are more preferable. The group chain structure has, when defining the mass ratio, the ratio of the total mass W ^G of the base relative to the total weight W ^S of the chain structure portion ^[W G ^/ W ^S] is not less than 0.05 Preferably, it is more preferably 0.1 or more, further preferably 0.2 or more, and particularly preferably 0.3 or more. The upper limit is not particularly limited, and can be, for example, 0.7 or less, and preferably 0.5 or less.
When the chain structure has a branched chain (such as a substituent), the mass of the branched structure and the mass of the hydrogen atom at the end of the molecular chain are also included in the total mass of the chain structure.
The number of the above groups in one molecule of the polymer is not particularly limited as long as the number of the above constituent components is satisfied, and is appropriately set.
The type of the group contained in the chain structure portion may be at least one type, and may be two or more types.

The side chain preferably has a partial structure represented by any of the following formulas (I) to (III), and more preferably has a partial structure represented by the following formula (II) or (III). More preferably, it has a partial structure represented by the following formula (III).
The position at which these partial structures are incorporated into the side chain is not particularly limited, but it is preferable that the carbonyl group in each structure be incorporated at a position at least four atoms away from the atoms constituting the main chain.

In the formula, L ¹ to L ⁴ each represent a linking group.
The linking group that can be taken as L ¹ to L ⁴ is not particularly limited, and examples thereof include an alkylene group (preferably having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 3), and an arylene group. (The number of carbon atoms is preferably 6 to 24, more preferably 6 to 14, and particularly preferably 6 to 10.) A heteroarylene group having 3 to 12 carbon atoms, an ether group (—O—), and a sulfide group (—S— ), A carbonyl group, an imino group (—NR ^N —: R ^N is a bonding site, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms), or two or more of these (preferably Is 2 to 10). Above all, as the linking group that can be taken as L ¹ to L ⁴ , an alkylene group is preferable, and as the linking group that can be taken as L ⁴ , methylene is more preferable. The number of members of the ring formed by L ² and L ³ together with the two carbon atoms in the formula is not particularly limited, but is preferably a 4- to 8-membered ring, more preferably a 5- or 6-membered ring.

In the above formulas (I) and (III), R ¹ and R ² each represent a substituent. However, R ¹ does not take “—L ⁴ —CO—R ² ” in the formula (III).
The substituents that can be taken as R ¹ and R ² are not particularly limited, and include an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 3), and an aryl group (having a carbon number of 1 to 3). 6 to 22, preferably 6 to 14, and more preferably 6 to 10), and a group containing a hetero atom. The hetero atom is not particularly limited, but is preferably an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, or the like. Examples of the group containing a hetero atom include a group containing a hetero atom in the group, a group bonded to the carbonyl carbon atom in each formula by the above hetero atom, and the like. For example, a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms, preferably a 5- or 6-membered heterocyclic group having at least one oxygen atom, sulfur atom and nitrogen atom. Includes an aromatic heterocyclic group and an aliphatic heterocyclic group.), An alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, and a substituted or unsubstituted amino group. No.
The substituent which can be taken as R ¹ is preferably a group containing a hetero atom, and the substituent which can be taken as R ² is preferably an alkyl group.
The carbon number of each of the alkoxy group and the alkylthio group is preferably 1 to 10, more preferably 1 to 6, and particularly preferably 1 to 3. Each of the aryloxy group and the arylthio group preferably has 6 to 24 carbon atoms, more preferably has 6 to 14 carbon atoms, and particularly preferably has 6 to 10 carbon atoms.

The substituents that can be taken as R ¹ and R ² may further have a substituent, such as an alkyl group, an aryl group, an amino group, a (diamino) phosphoryl group, an ether group, or A group in which two or more (preferably 2 to 10) are combined is exemplified.
The substituents that can be taken as R ¹ and R ² are L ¹ or L ⁴ , or a linking group that links the structure represented by each of the above-mentioned formulas and the main chain of the polymer to form a cyclohexane ring, cyclohexene It may form a ring such as a ring.

In each of the above formulas, ** indicates a bonding portion to the main chain (atom constituting the polymer) of the polymer.
The partial structure represented by each of the above formulas may be directly bonded to the main chain of the polymer, but is preferably bonded via a linking group. The linking group that bonds the partial structure represented by each formula to the main chain of the polymer is not particularly limited, and examples thereof include linking groups that can be taken as L ¹ to L ⁴ , and among them, an alkylene group, an arylene group , A heteroarylene group, an ether group, a sulfide group, a carbonyl group or an imino group, or a linking group obtained by combining two or more (preferably 2 to 10) thereof, and is preferably an alkylene group, an ether group, a sulfide group or a carbonyl group. Alternatively, a linking group in which two or more (preferably 2 to 10) of them are combined is more preferable, and -alkylene-S-, -C (= O) -O-, or -alkylene-S-alkylene-C ( = O) -O-alkylene-O- groups are more preferred.

において In the present invention, the number of atoms constituting the linking group is preferably 1 to 30, more preferably 3 to 20, and still more preferably 5 to 15. The number of linking atoms of the linking group is preferably from 1 to 15, more preferably from 5 to 12. The number of connected atoms means the minimum number of atoms connecting predetermined structural parts. For example, in the case of —C (＝ O) —O—, the number of atoms constituting the linking group is 3, but the number of linking atoms is 2.

In the polymer having a component having a side chain satisfying the above conditions A and B, the content of the component can be appropriately set.
It is preferable that the content of each component relative to the total number of moles of all components forming the polymer be determined from the following range so as to be 100 mol% in total.
Among the components represented by the formula (I-1) or (I-2), the content of the component (RP1 in the examples described later) in which R ^P1 is a hydrocarbon group is determined by the hydrogen bond formation. From the viewpoint of film strength due to, for example, the amount is preferably 50 to 10 mol%, more preferably 50 to 20 mol%, and more preferably 50 to 30 mol%, based on all the constituent components forming the polymer. Is more preferred.
Further, among the components represented by the above formula (I-3) or (I-4), the content of the component (RP M2 in Examples described later) in which R ^P2 is a hydrocarbon group is hydrogen. From the viewpoint of film strength due to bond formation and the like, the content is preferably 50 to 1 mol%, more preferably 40 to 2 mol%, and more preferably 30 to 3 mol%, based on all constituent components forming the polymer. It is even more preferred.
The content of each of the above components is the content of the components that do not contain the above-mentioned side chains and do not have the above-mentioned side chains.

The content of the component represented by the formula (I-1) or (I-2) in which ^RP2 is the above-mentioned molecular chain depends on the content of the polymer formed from the viewpoint of improving the flexibility of the film. The content is preferably 50 to 10 mol%, more preferably 50 to 20 mol%, even more preferably 50 to 30 mol%, based on all the constituent components.
Further, among the components represented by the above formula (I-3) or (I-4), the content of a component (RP M1 in Examples described later) in which R ^P1 is the above molecular chain is determined by the film. From the viewpoint of improving the flexibility of the polymer, it is preferably from 50 to 1 mol%, more preferably from 40 to 2 mol%, and more preferably from 20 to 3 mol%, based on all constituent components forming the polymer. Is more preferred.
The content of each of the above components is the content of the components that do not contain the above-mentioned side chains and do not have the above-mentioned side chains.

The content of the component having the side chain (component M3 in Examples described later) is 80 to 5 mol% with respect to all components forming the polymer in terms of interaction with the negative electrode active material. Preferably, it is 80 to 10 mol%, more preferably 60 to 15 mol%, and particularly preferably 40 to 15 mol%.
When the polymer has other components other than the above components, the content of the other components is preferably 15 mol% or less based on all the components forming the polymer.

It is preferable that the content of each component relative to the total mass of all components forming the polymer is determined so as to be 100% by mass in total from the following range.
Among the components represented by the formula (I-1) or (I-2), the content of the component in which R ^P1 is a hydrocarbon group depends on the polymer strength in terms of film strength due to hydrogen bond formation and the like. The amount is preferably from 80 to 20% by mass, more preferably from 70 to 30% by mass, even more preferably from 60 to 35% by mass, based on the total mass of all constituent components to be formed.
Further, among the components represented by the above formula (I-3) or (I-4), the content of the component in which R ^P2 is a hydrocarbon group is determined in terms of film strength due to hydrogen bond formation and the like. The amount is preferably from 80 to 20% by mass, more preferably from 70 to 30% by mass, even more preferably from 60 to 35% by mass, based on the total mass of all the constituent components forming the polymer.
The content of each of the above components is the content of the components that do not contain the above-mentioned side chains and do not have the above-mentioned side chains.

The content of the component represented by the above formula (I-1) or (I-2) in which ^RP1 is the above-mentioned molecular chain is determined from the viewpoint of improving the flexibility of the film. It is preferably from 80 to 20% by mass, more preferably from 70 to 30% by mass, even more preferably from 60 to 35% by mass, based on the total mass of all the constituent components.
In addition, among the components represented by the above formula (I-3) or (I-4), the content of the component in which ^RP2 is the above molecular chain is determined from the viewpoint of improving the flexibility of the film. Is preferably from 80 to 20% by mass, more preferably from 70 to 30% by mass, even more preferably from 60 to 35% by mass, based on the total mass of all the constituent components forming the polymer.
The content of each of the above components is the content of the components that do not contain the above-mentioned side chains and do not have the above-mentioned side chains.

The content of the component having the side chain is preferably 41 to 1% by mass, and more preferably 40 to 1% by mass with respect to the total mass of all the components constituting the polymer in terms of interaction with the negative electrode active material. The content is more preferably 5% by mass, further preferably 20 to 5% by mass, and particularly preferably 10 to 5% by mass.
When the polymer has other components other than the above components, the content of the other components is preferably 15% by mass based on all the components forming the polymer.

Since the polymer has a component having the above-described side chain, the polymer may not have a known group having an adsorptivity to solid particles such as a negative electrode active material, a positive electrode active material, an inorganic solid electrolyte, and the like. May further have a group exhibiting an adsorptivity in order to further improve the binding property with the compound. The group exhibiting adsorptivity is not particularly limited, and examples thereof include groups included in “functional group (II)” described in WO2018 / 020827.

The polymer can be synthesized by polycondensation of a raw material compound by a known method according to the type of the bond in the main chain. As the synthesis method, for example, “<(B) Method for synthesizing polymer>” described in WO2018 / 020827 can be referred to.

(Physical properties of polymer, etc.)
The above-mentioned polymer (binder made of a polymer) may be soluble in the dispersion medium, but is preferably insoluble (particles) in the dispersion medium particularly from the viewpoint of ion conductivity.
In the present invention, the term “insoluble in a dispersion medium” means that a polymer is added to a dispersion medium at 30 ° C. (the amount used is 10 times the mass of the polymer) and left standing for 24 hours. Means 3% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less. The amount of dissolution is defined as the ratio of the mass of the polymer obtained from the dispersion medium that has been solid-liquid separated after 24 hours to the mass of the polymer added to the dispersion medium.

The polymer (binder) may be present in the negative electrode composition, for example, dissolved in a dispersion medium, or may be present (preferably dispersed) in a solid state without being dissolved in the dispersion medium (solid). Binders that are present in the form of particles are referred to as particulate binders). In the present invention, the polymer (binder) is preferably a particulate binder in the negative electrode composition and further in the negative electrode active material layer (coating dried layer), from the viewpoint of battery resistance and cycle characteristics.

When the binder is a particulate binder, its shape is not particularly limited and may be flat, amorphous, or the like, but is preferably spherical or granular.
The average particle size of the particulate binder is not particularly limited, but is preferably 1,000 nm or less, more preferably 500 nm or less, and even more preferably 300 nm or less. The lower limit is 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 50 nm or more. The average particle size can be measured in the same manner as the above-mentioned average particle size of the inorganic solid electrolyte.

-Weight average molecular weight-
The weight average molecular weight of the polymer is not particularly limited. For example, it is preferably 3,000 or more, more preferably 5,000 or more, still more preferably 7,000 or more, and particularly preferably 10,000 or more. The upper limit is substantially 1,000,000 or less, preferably 300,000 or less, more preferably 200,000 or less, and even more preferably 100,000 or less.
-Measurement of molecular weight-
In the present invention, the mass average molecular weight is measured by gel permeation chromatography (GPC) in terms of standard polystyrene. The measurement method is basically a value measured by the method of the following condition 1 or condition 2 (priority). However, an appropriate eluent may be appropriately selected and used depending on the type of the polymer (polymer or the like) to be measured.
(Condition 1)
Column: connect two TOSOH TSKgel Super AWM-H carriers: 10 mM LiBr / N-methylpyrrolidone Measurement temperature: 40 ° C.
Carrier flow rate: 1.0 ml / min
Sample concentration: 0.1% by mass
Detector: RI (refractive index) detector (Condition 2)
Column: Use a column connected with TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, and TOSOH TSKgel Super HZ2000 Carrier: Tetrahydrofuran Measurement temperature: 40 ° C.
Carrier flow rate: 1.0 ml / min
Sample concentration: 0.1% by mass
Detector: RI (refractive index) detector

This polymer may be a non-crosslinked polymer or a crosslinked polymer. When the crosslinking of the polymer proceeds by heating or application of voltage, the molecular weight may be higher than the above molecular weight. Preferably, the polymer has a weight average molecular weight in the above range at the start of use of the all solid state secondary battery.

－ Moisture concentration －
The water concentration of the polymer is preferably 100 ppm (by mass) or less. The polymer may be crystallized and dried, or the polymer dispersion may be used as it is.

- Glass-transition temperature -
The glass transition temperature of the polymer is not particularly limited, but is preferably 30 ° C. or lower, more preferably 25 ° C. or lower, further preferably 15 ° C. or lower, and particularly preferably 5 ° C. or lower. . The lower limit of the glass transition temperature is not particularly limited and can be set, for example, to -200 ° C, is preferably -150 ° C or higher, and more preferably -120 ° C or higher.

The glass transition temperature (Tg) is measured using a differential scanning calorimeter: X-DSC7000 (trade name, manufactured by SII Nanotechnology Co., Ltd.) on a dry sample of the polymer under the following conditions. The measurement is performed twice with the same sample, and the result of the second measurement is adopted.
Atmosphere in measurement room: Nitrogen gas (50 mL / min)
Heating rate: 5 ° C / min
Measurement start temperature: -100 ° C
Measurement end temperature: 200 ° C
Sample pan: Aluminum pan Mass of sample: 5mg
Calculation of Tg: Tg is calculated by rounding the decimal point of the intermediate temperature between the descent start point and descent end point of the DSC chart.
In the case of using an all-solid secondary battery, for example, after disassembling the all-solid secondary battery and putting the active material layer or solid electrolyte layer in water to disperse the material, filtration is performed, and the remaining solid Can be collected and the glass transition temperature can be measured by the above-mentioned measuring method.

The binder included in the composition for a negative electrode of the present invention may include a binder other than the binder including the polymer having the constituent component having the side chain satisfying the above conditions A and B. Examples of such a binder include a binder contained in a solid electrolyte composition described later (a binder composed of various polymers described in the solid electrolyte composition). When the binder contains a binder other than a binder having a component having a side chain that satisfies the above conditions A and B, all of the binder having a polymer having a side chain that satisfies the above conditions A and B, The content in the binder is not particularly limited, but is preferably, for example, 10 to 100% by mass.
The negative electrode composition may contain one kind of binder or two or more kinds of binders.

The content of the binder in the negative electrode composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and more preferably 0.3% by mass or more in the solid content. It is particularly preferred that there is. The upper limit is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

<Negative electrode active material>
The composition for a negative electrode of the present invention contains a negative electrode active material as an active material capable of inserting and releasing ions of a metal belonging to

Group

1 or 2 of the periodic table.
As the negative electrode active material, those capable of reversibly inserting and / or releasing lithium ions are preferable. The material is not particularly limited as long as it has the above characteristics. Carbonaceous materials, metal oxides, metal composite oxides, lithium alone, lithium alloys, alloyable with lithium (forming alloys with lithium) Negative electrode active material and the like. Among them, a carbonaceous material, a metal composite oxide or lithium alone is preferably used from the viewpoint of reliability. An active material that can be alloyed with lithium is preferable in that the capacity of the all-solid secondary battery can be increased. In the negative electrode active material formed using the negative electrode composition of the present invention, the solid particles are firmly bound to each other, and thus the above-described active material that can be alloyed with lithium can be used as the negative electrode active material.

炭素 A carbonaceous material used as a negative electrode active material is a material substantially composed of carbon. For example, various synthetics such as petroleum pitch, carbon black such as acetylene black (AB), graphite (artificial graphite such as natural graphite and vapor-grown graphite), and PAN (polyacrylonitrile) -based resin or furfuryl alcohol resin. A carbonaceous material obtained by firing a resin can be used. Further, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol) -based carbon fiber, lignin carbon fiber, glassy carbon fiber, and activated carbon fiber. , Mesophase microspheres, graphite whiskers, flat graphite, and the like.

These carbonaceous materials can be classified into non-graphitizable carbonaceous materials (also referred to as hard carbon) and graphite-based carbonaceous materials according to the degree of graphitization. Further, the carbonaceous material preferably has a plane spacing or a density and a crystallite size described in JP-A-62-22066, JP-A-2-6856 and JP-A-3-45473. The carbonaceous material does not need to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, or the like may be used. Can also.
As the carbonaceous material, hard carbon or graphite is preferably used, and graphite is more preferably used.

The oxide of the metal or metalloid element applied as the negative electrode active material is not particularly limited as long as it is an oxide capable of occluding and releasing lithium. An oxide of the metal element (metal oxide), a composite of the metal element An oxide or a composite oxide of a metal element and a metalloid element (collectively, a metal composite oxide) and an oxide of a metalloid element (metalloid oxide) are given. As these oxides, amorphous oxides are preferable, and chalcogenite which is a reaction product of a metal element and an element of Group 16 of the periodic table is also preferable. In the present invention, the term “metalloid element” refers to an element having an intermediate property between a metal element and a nonmetalloid element, and usually includes six elements of boron, silicon, germanium, arsenic, antimony, and tellurium, and further includes selenium. , Polonium and astatine. The term “amorphous” means an X-ray diffraction method using CuKα rays having a broad scattering band having an apex in a range of 20 ° to 40 ° in 2θ value. May have. The strongest intensity of the crystalline diffraction lines observed at 40 ° to 70 ° in the 2θ value is 100 times or less the intensity of the diffraction line at the apex of the broad scattering band observed at 20 ° to 40 ° in the 2θ value. It is more preferably 5 times or less, particularly preferably no crystalline diffraction line.

Among the compound group consisting of the above-mentioned amorphous oxide and chalcogenide, an amorphous oxide of a metalloid element or the above-mentioned chalcogenide is more preferable, and an element of group 13 (IIIB) to group 15 (VB) of the periodic table (for example, , Al, Ga, Si, Sn, Ge, Pb, Sb and Bi), a (composite) oxide composed of one or a combination of two or more thereof, or a chalcogenide is particularly preferred. Specific examples of preferable amorphous oxides and chalcogenides include, for example, Ga ₂ O ₃ , GeO, PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₈ Bi ₂ O ₃ , Sb ₂ O ₈ Si ₂ O ₃ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , GeS, PbS, PbS ₂ , Sb ₂ S ₃ or Sb ₂ S ₅ is a preferred example.
Examples of the negative electrode active material that can be used in combination with an amorphous oxide centering on Sn, Si, and Ge include a carbonaceous material that can occlude and / or release lithium ions or lithium metal, simple lithium, a lithium alloy, and lithium. An active material that can be alloyed with is preferably used.

An oxide of a metal or metalloid element, particularly a metal (composite) oxide and the above-described chalcogenide preferably contain at least one of titanium and lithium as a component from the viewpoint of high current density charge / discharge characteristics. Examples of the lithium-containing metal composite oxide (lithium composite metal oxide) include, for example, a composite oxide of lithium oxide and the metal (composite) oxide or the chalcogenide, more specifically, Li ₂ SnO _2. No.
The negative electrode active material, for example, a metal oxide also preferably includes a titanium atom (titanium oxide). Specifically, Li ₄ Ti ₅ O ₁₂ (lithium titanate [LTO]) is excellent in rapid charge / discharge characteristics due to small volume fluctuation at the time of occlusion and release of lithium ions. This is preferable in that the life of the battery can be improved.

リチウム The lithium alloy as the negative electrode active material is not particularly limited as long as it is an alloy generally used as a negative electrode active material of a secondary battery, and examples thereof include a lithium aluminum alloy.

The active material that can be alloyed with lithium is not particularly limited as long as it is commonly used as a negative electrode active material of a secondary battery. Such an active material has a large expansion and contraction due to charge and discharge of the all-solid secondary battery, and accelerates a decrease in cycle characteristics.However, since the negative electrode composition of the present invention contains the binder described above, a decrease in cycle characteristics is caused. Can be suppressed. Examples of such an active material include (negative electrode) active materials (alloys and the like) having a silicon element or a tin element, and metals such as Al and In, which include a silicon element that enables higher battery capacity as a constituent element. A silicon-based negative electrode active material (silicon element-containing active material) is preferable, and a silicon element-containing active material having a silicon element content of 50 mol% or more of all constituent elements is more preferable.
Generally, a negative electrode containing such a negative electrode active material (a Si negative electrode containing a silicon element-containing active material, a Sn negative electrode containing a tin element-containing active material) is used as a carbon negative electrode (eg, graphite and acetylene black). In comparison, more Li ions can be stored. That is, the storage amount of Li ions per unit mass increases. Therefore, the battery capacity can be increased. As a result, there is an advantage that the battery driving time can be extended.
Examples of the silicon element-containing active material include silicon materials such as Si and SiOx (0 <x ≦ 1), and silicon-containing alloys including titanium, vanadium, chromium, manganese, nickel, copper, and lanthanum (for example, LaSi ₂ , VSi ₂ , La—Si, Gd—Si, Ni—Si), or an organized active material (eg, LaSi ₂ / Si), as well as silicon and tin elements such as SnSiO ₃ and SnSiS ₃ And the like. Note that SiOx itself can be used as a negative electrode active material (semi-metal oxide). Further, since Si is generated by the operation of an all-solid secondary battery, a negative electrode active material that can be alloyed with lithium (the Precursor material).
Examples of the negative electrode active material having a tin element include Sn, SnO, SnO ₂ , SnS, SnS ₂ , and an active material containing the above silicon element and tin element. Further, a composite oxide with lithium oxide, for example, Li ₂ SnO ₂ can also be used.

In the present invention, the above-described negative electrode active material can be used without any particular limitation.However, in terms of battery capacity, a negative electrode active material that can be alloyed with lithium is a preferable embodiment. The above-mentioned silicon material or silicon-containing alloy (alloy containing a silicon element) is more preferable, and silicon (Si) or a silicon-containing alloy is further preferable.

In the present invention, the chemical formula of the compound obtained by the calcination method can be calculated from inductively coupled plasma (ICP) emission spectroscopy as a measuring method, and from the mass difference of powder before and after calcination as a simple method.

(Coating of negative electrode active material)
The surface of the negative electrode active material may be coated with another metal oxide. Examples of the surface coating agent include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si or Li. Specific examples include titanate spinel, tantalum-based oxide, niobium-based oxide, lithium niobate-based compound, and the like. Specifically, Li ₄ Ti ₅ O ₁₂ , Li ₂ Ti ₂ O ₅ , and LiTaO ₃ , LiNbO ₃ , LiAlO ₂ , Li ₂ ZrO ₃ , Li ₂ WO ₄ , Li ₂ TiO ₃ , Li ₂ B ₄ O ₇ , Li ₃ PO ₄ , Li ₂ MoO ₄ , Li ₃ BO ₃ , LiBO ₂ , Li ₂ CO ₃ , Li ₂ SiO ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , B ₂ O _{3 and the} like.
The surface of the electrode containing the negative electrode active material may be surface-treated with sulfur or phosphorus.
Further, the surface of the particles of the negative electrode active material may be subjected to a surface treatment before or after the above-mentioned surface coating with an active ray or an active gas (plasma or the like).

形状 The shape of the negative electrode active material is not particularly limited, but is preferably in the form of particles. The average particle size of the negative electrode active material is not particularly limited, but is preferably 0.1 to 60 μm. The average particle size of the negative electrode active material particles can be measured in the same manner as the average particle size of the inorganic solid electrolyte. In order to make the negative electrode active material have a predetermined particle size, an ordinary pulverizer or a classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air jet mill, or a sieve is preferably used. At the time of pulverization, wet pulverization in the presence of water or an organic solvent such as methanol can also be performed. Classification is preferably performed to obtain a desired particle size. Classification is not particularly limited, and can be performed using a sieve, an air classifier, or the like. Classification can be performed both in a dry process and in a wet process.

The composition for the negative electrode may contain one kind of the negative electrode active material or may contain two or more kinds of the negative electrode active material.

The content of the negative electrode active material in the negative electrode composition is not particularly limited, and is preferably 10 to 90% by mass, more preferably 20 to 85% by mass, and more preferably 30 to 80% by mass at a solid content of 100% by mass. %, More preferably 40 to 75% by mass.

<Dispersion medium>
The composition for a negative electrode of the present invention contains a dispersion medium (dispersion medium).
The dispersing medium may be any as long as it disperses or dissolves the above-mentioned components, but preferably disperses at least without dissolving the binder. Examples of the dispersion medium contained in the negative electrode composition include various organic solvents. Examples of the organic solvent include alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic compounds, aliphatic compounds, nitrile compounds, ester compounds, and other solvents. Specific examples of the dispersion medium include the following. One.

Examples of the alcohol compound include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, -Methyl-2,4-pentanediol, 1,3-butanediol and 1,4-butanediol.

Examples of the ether compound include alkylene glycol (diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, etc.), alkylene glycol alkyl ether (ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl). Ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether, etc., dialkyl ether (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), cyclic ether ( Tetrahydrofuran, dioxane (1,2, including 1,3- and 1,4-isomers of), etc.).

Examples of the amide compound include N, N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidinone, ε-caprolactam, formamide, N- Examples include methylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropanamide, hexamethylphosphoric triamide and the like.

Examples of the amine compound include triethylamine, diisopropylethylamine, tributylamine and the like.
Examples of the ketone compound include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diisobutyl ketone, and the like.
Examples of the aromatic compound include benzene, toluene, xylene and the like.
Examples of the aliphatic compound include hexane, heptane, octane, decane and the like.
Examples of the nitrile compound include acetonitrile, propylonitrile, isobutyronitrile and the like.
Examples of the ester compound include ethyl acetate, butyl acetate, propyl acetate, butyl butyrate, and butyl pentanoate.
Examples of the non-aqueous dispersion medium include the above aromatic compounds and aliphatic compounds.

において In the present invention, among them, ketone compounds, aromatic compounds, aliphatic compounds and ester compounds are preferable, and ketone compounds, aliphatic compounds and ester compounds are more preferable. In the present invention, it is preferable to further select the above specific organic solvent using a sulfide-based inorganic solid electrolyte. By selecting this combination, a sulfide-based inorganic solid electrolyte can be stably handled because a functional group active with respect to the sulfide-based inorganic solid electrolyte is not included. Particularly, a combination of a sulfide-based inorganic solid electrolyte and an aliphatic compound is preferable.

The dispersion medium preferably has a boiling point at normal pressure (1 atm) of 50 ° C or higher, more preferably 70 ° C or higher. The upper limit is preferably 250 ° C or lower, more preferably 220 ° C or lower.
The composition for a negative electrode may contain one type of dispersion medium or two or more types.

において In the present invention, the content of the dispersion medium in the negative electrode composition is not particularly limited and can be appropriately set. For example, in the composition for a negative electrode, the amount is preferably 20 to 99% by mass, more preferably 25 to 70% by mass, and particularly preferably 30 to 60% by mass.

<Conduction aid>
The composition for a negative electrode of the present invention may appropriately contain a conductive additive used for improving the electronic conductivity of the active material. As the conductive assistant, a general conductive assistant can be used. For example, electron conductive materials such as natural graphite, graphite such as artificial graphite, carbon black such as acetylene black, Ketjen black, furnace black, amorphous carbon such as needle coke, vapor grown carbon fiber or carbon nanotube Carbon fibers such as graphene or fullerene; metal powders such as copper and nickel; metal fibers; and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives. May be used. One of these may be used, or two or more thereof may be used. The shape of the conductive additive is not particularly limited, but is preferably in the form of particles.
When the composition for a negative electrode of the present invention contains a conductive additive, the content of the conductive additive in the composition for a negative electrode is preferably 0 to 10% by mass based on 100% by mass of solid content.
In the present invention, when an active material and a conductive auxiliary are used in combination, of the above conductive auxiliary, ions of a metal belonging to the first or second group of the periodic table (preferably Li) when the battery is charged and discharged. A substance that does not cause insertion and release of ions and does not function as an active material is defined as a conductive assistant. Therefore, among the conductive assistants, those that can function as an active material in the active material layer when the battery is charged and discharged are classified as active materials rather than conductive assistants. Whether or not the battery functions as an active material when charged and discharged is not unique and is determined by a combination with the active material.

<Lithium salt>
The composition for a negative electrode of the present invention also preferably contains a lithium salt (supporting electrolyte).
As the lithium salt, a lithium salt usually used for this kind of product is preferable, and there is no particular limitation. For example, lithium salts described in paragraphs 0082 to 0085 of JP-A-2015-088486 are preferable.
When the composition for a negative electrode of the present invention contains a lithium salt, the content of the lithium salt is preferably at least 0.1 part by mass, more preferably at least 5 parts by mass, based on 100 parts by mass of the solid electrolyte. As a maximum, 50 mass parts or less are preferred, and 20 mass parts or less are more preferred.

<Dispersant>
The composition for a negative electrode of the present invention may contain a dispersant. As the dispersant, those commonly used in all solid-state secondary batteries can be appropriately selected and used. Generally, compounds intended for particle adsorption and steric repulsion and / or electrostatic repulsion are preferably used.

<Other additives>
The composition for a negative electrode of the present invention may further include, if desired, an ionic liquid, a thickener, a crosslinking agent (such as one that undergoes a cross-linking reaction by radical polymerization, condensation polymerization, or ring-opening polymerization) as a component other than the above-described components. It may contain an initiator (such as one that generates an acid or a radical by heat or light), an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant and the like. The ionic liquid is contained for further improving the ionic conductivity, and a known ionic liquid can be used without any particular limitation.

<Preparation of composition for negative electrode>
The composition for a negative electrode of the present invention, an inorganic solid electrolyte, a binder, a negative electrode active material, a dispersion medium, and any other components, for example, by mixing with various commonly used mixers, as a mixture, preferably as a slurry Can be prepared.
The mixing method is not particularly limited, and they may be mixed at once or may be mixed sequentially. The mixing environment is not particularly limited, and examples thereof include under dry air or under an inert gas.
When the composition for the negative electrode is prepared as a dispersion, the method for dispersing the binder is not particularly limited, and a known emulsification method such as a method for synthesizing the polymer (for example, an emulsion polymerization method) and a phase inversion emulsification method can be applied.

[Negative electrode sheet for all solid state secondary batteries]
The negative electrode sheet for an all-solid secondary battery of the present invention has a negative electrode active material layer composed of the above-described negative electrode composition of the present invention. Therefore, the negative electrode active material layer of the negative electrode sheet for an all solid state secondary battery of the present invention has both a high resistance and a high film strength. Further, the negative electrode active material layer is firmly bound to the negative electrode current collector. The negative electrode sheet for an all-solid secondary battery of the present invention having such a negative electrode active material layer can provide the all-solid secondary battery with characteristics of reducing battery resistance and maintaining a high discharge capacity, It can be preferably used as a material for forming a negative electrode active material layer of a battery.

The negative electrode sheet for an all-solid secondary battery of the present invention (may be simply referred to as a negative electrode sheet) may be a sheet having the above-described negative electrode active material layer. ) May be a sheet formed thereon or a sheet having no base material and formed from a negative electrode active material layer. The substrate is not particularly limited as long as it can support the negative electrode active material layer, and includes a sheet (plate-like body) such as a material described below for an anode current collector, an organic material, and an inorganic material. . Examples of the organic material include various polymers, and specific examples include polyethylene terephthalate, polypropylene, polyethylene, and cellulose. Examples of the inorganic material include glass and ceramic.
The negative electrode sheet for an all-solid-state secondary battery of the present invention is generally a sheet having a negative electrode current collector and a negative electrode active material layer, and has a negative electrode current collector, a negative electrode active material layer and a solid electrolyte layer in this order, In addition, an embodiment having a negative electrode current collector, a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer in this order is also included. This negative electrode sheet may have other layers such as a protective layer (release sheet), a current collector, and a coat layer.
The layer thickness of each layer constituting the negative electrode sheet is the same as the layer thickness of each layer described in the all solid state secondary battery described later. The content of each component in the negative electrode active material layer of the negative electrode sheet is not particularly limited, but is preferably the same as the content of each component in the solid content of the electrolyte composition (composition for negative electrode) of the present invention. .

[Method for producing negative electrode sheet for all-solid secondary battery]
The method for producing the negative electrode sheet for an all-solid secondary battery of the present invention is not particularly limited, and the negative electrode sheet can be produced by forming the negative electrode composition of the present invention into a film to form a negative electrode active material layer. For example, the negative electrode composition of the present invention is preferably formed (coated and dried) on a substrate (may be via another layer) to form a negative electrode active material layer (coated and dried layer). Method. Thereby, a negative electrode sheet for an all-solid secondary battery having a substrate and a coating and drying layer can be produced. Here, the coating dry layer is a negative electrode active material layer formed by applying the negative electrode composition of the present invention and drying the dispersion medium (that is, the negative electrode active material layer formed using the negative electrode composition of the present invention. Negative electrode active material layer having a composition obtained by removing the dispersion medium from the negative electrode composition of the present invention). The dried coating layer may contain a dispersion medium even after drying, as long as the effect of the present invention is not impaired. For example, the coating medium is contained (remaining) in a content of 1% by mass or less based on the total mass of the dried coating layer. Is also good.
In the method for producing a negative electrode sheet for an all-solid secondary battery of the present invention, each step of coating and drying will be described in the following method for producing an all-solid secondary battery.

In the method for producing a negative electrode sheet for an all-solid secondary battery of the present invention, the coated and dried layer obtained as described above may be pressed. As the pressing conditions and the like, the conditions in the method for manufacturing an all-solid secondary battery described below can be applied, but the pressing force may be, for example, 3 to 2000 MPa.
Further, in the method for producing a negative electrode sheet for an all-solid secondary battery of the present invention, the base material, the protective layer (particularly, a release sheet), and the like can be peeled off.

[All-solid secondary battery]
The all solid state secondary battery of the present invention includes a positive electrode active material layer, a negative electrode active material layer opposed to the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. Have. The positive electrode active material layer is preferably formed on a positive electrode current collector and forms a positive electrode. The negative electrode active material layer is preferably formed on a negative electrode current collector to form a negative electrode.
In the all solid state secondary battery of the present invention, the negative electrode active material layer is preferably formed of the composition for a negative electrode of the present invention, and the positive electrode active material layer and the solid electrolyte layer are made of a known material, for example, a positive electrode active material described later. Alternatively, it is formed of a positive electrode composition, a solid electrolyte composition, or the like. The negative electrode active material layer formed of the composition for a negative electrode of the present invention has both a high level of suppression of resistance increase and an improvement in film strength, and the all-solid secondary battery has a low battery resistance and a high discharge capacity. It contributes to achieving maintainable characteristics. The negative electrode active material layer formed of the composition for a negative electrode of the present invention is preferably the same as the solid component of the composition for a negative electrode of the present invention with respect to the types of components contained and the content ratio thereof.
The thicknesses of the negative electrode active material layer, the solid electrolyte layer, and the positive electrode active material layer are not particularly limited. The thickness of each layer is preferably 10 to 1,000 μm, more preferably 20 μm or more and less than 500 μm, in consideration of the dimensions of a general all solid state secondary battery. In the all solid state secondary battery of the present invention, it is more preferable that at least one of the positive electrode active material layer and the negative electrode active material layer has a thickness of 50 μm or more and less than 500 μm.

(Housing)
The all-solid-state secondary battery of the present invention may be used as an all-solid-state secondary battery with the above structure depending on the application. Is preferred. The housing may be made of metal or resin (plastic). When a metallic material is used, for example, an aluminum alloy or a stainless steel material can be used. It is preferable that the metallic casing is divided into a casing on the positive electrode side and a casing on the negative electrode side, and electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. It is preferable that the housing on the positive electrode side and the housing on the negative electrode side are joined and integrated via a gasket for preventing short circuit.

Hereinafter, an all-solid secondary battery according to a preferred embodiment of the present invention will be described with reference to FIG. 1, but the present invention is not limited to this.

FIG. 1 is a cross-sectional view schematically illustrating an all solid state secondary battery (lithium ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 of the present embodiment includes a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in this order as viewed from the negative electrode side. . Each layer is in contact with each other and has an adjacent structure. By employing such a structure, at the time of charging, electrons (e ⁻ ) are supplied to the negative electrode side, and lithium ions (Li ⁺ ) are accumulated therein. On the other hand, at the time of discharging, lithium ions (Li ⁺ ) accumulated in the negative electrode are returned to the positive electrode side, and electrons are supplied to the operating portion 6. In the example shown in the figure, a light bulb is employed as a model for the operating part 6, and this is turned on by discharge.

When the all-solid secondary battery having the layer configuration shown in FIG. 1 is placed in a 2032 type coin case, this all-solid secondary battery is referred to as an all-solid secondary battery electrode sheet, and the all-solid secondary battery electrode sheet is referred to as an all-solid secondary battery electrode sheet. A battery manufactured in a 2032 type coin case is sometimes referred to as an all solid state secondary battery.

(Positive electrode active material layer, solid electrolyte layer, negative electrode active material layer)
In the all-solid secondary battery 10, the negative electrode active material layer is formed of the negative electrode composition of the present invention. The positive electrode active material layer and the solid electrolyte layer are formed of a positive electrode active material sheet or a positive electrode composition described later, or a solid electrolyte composition. The all-solid-state secondary battery 10 including the negative electrode active material layer exhibits excellent battery performance (characteristics capable of maintaining low battery resistance and high discharge capacity).

The positive electrode current collector 5 and the negative electrode current collector 1 are preferably electronic conductors.
In the present invention, one or both of the positive electrode current collector and the negative electrode current collector may be simply referred to as a current collector.
As the material for forming the positive electrode current collector, in addition to aluminum, aluminum alloy, stainless steel, nickel and titanium, a material obtained by treating a surface of aluminum or stainless steel with carbon, nickel, titanium or silver (forming a thin film) Are preferred, and among them, aluminum and an aluminum alloy are more preferred.
As materials for forming the negative electrode current collector, in addition to aluminum, copper, copper alloy, stainless steel, nickel and titanium, etc., the surface of aluminum, copper, copper alloy or stainless steel is treated with carbon, nickel, titanium or silver. Preferably, aluminum, copper, copper alloy and stainless steel are more preferred.

As the shape of the current collector, a film sheet is usually used, but a net, a punched material, a lath, a porous material, a foam, a molded product of a fiber group, and the like can also be used.
The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm. In addition, it is preferable that the surface of the current collector be provided with irregularities by surface treatment.

In the present invention, a functional layer, a member, or the like is appropriately interposed or provided between or outside each layer of the negative electrode current collector, the negative electrode active material layer, the solid electrolyte layer, the positive electrode active material layer, and the positive electrode current collector. May be. Each layer may be composed of a single layer, or may be composed of multiple layers.

[Manufacture of all solid state secondary battery]
The all-solid-state secondary battery can be manufactured by a conventional method, and can be preferably manufactured through a method of manufacturing a negative-electrode sheet for an all-solid-state secondary battery. More specifically, it can be manufactured by forming a negative electrode active material layer using the composition for a negative electrode of the present invention and the like, and forming a positive electrode active material layer and a solid electrolyte layer using known materials.
The composition for the negative electrode or the negative electrode sheet for the all-solid secondary battery used in the production of the all-solid secondary battery is as described above. Hereinafter, a material (composition or sheet) used for forming the positive electrode active material layer and the solid electrolyte layer in the method for manufacturing an all-solid secondary battery will be briefly described.

(Composition for positive electrode)
The positive electrode active material layer of the all solid state secondary battery can be formed of, for example, a positive electrode composition, a sheet made of the positive electrode active material, or the like.
As the composition for the positive electrode, a known composition can be used without any particular limitation. For example, a positive electrode active material, preferably an inorganic solid electrolyte, a binder, further a dispersion medium, a composition for a positive electrode containing other additives as appropriate, preferably, an inorganic solid electrolyte, a positive electrode active material, a binder and a dispersion And a composition for a positive electrode containing a solvent.
The composition for the positive electrode contains, as the inorganic solid electrolyte, the binder, the dispersion medium and the other additives, each can be used without particular limitation, and those in the negative electrode composition of the present invention May be the same or different. Among the binders contained in the composition for the positive electrode, a binder different from the binder containing the constituent component having the side chain that satisfies the above conditions A and B contained in the composition for the negative electrode of the present invention (hereinafter referred to as the composition for the negative electrode) And a binder different from the above.) May be a binder contained in a solid electrolyte composition described later. The contents of the binder, the dispersion medium and the other additives in the positive electrode composition can be set in the same ranges as the contents in the negative electrode composition of the present invention.
For example, the dispersed state and the water content of the positive electrode composition are preferably the same as those of the negative electrode composition of the present invention.
The composition for the positive electrode can be prepared in the same manner as the composition for the negative electrode.

－ Positive electrode active material －
The positive electrode composition contains a positive electrode active material as an active material capable of inserting and releasing ions of a metal belonging to

Group

1 or 2 of the periodic table.
It is preferable that the positive electrode active material be capable of reversibly inserting and / or releasing lithium ions. The material is not particularly limited as long as it has the above characteristics, and may be a transition metal oxide, an element such as sulfur, which can be combined with Li, or the like.
Among them, a transition metal oxide is preferably used as the positive electrode active material, and a transition metal oxide containing a transition metal element M ^a (at least one element selected from Co, Ni, Fe, Mn, Cu, and V). Are more preferred. In addition, the transition metal oxide includes an element M ^b (an element of the first (Ia) group, an element of the second (IIa) group, Al, Ga, In, Ge, Sn, Pb, Elements such as Sb, Bi, Si, P and B). The mixing amount is preferably 0 ~ 30 mol% relative to the amount of the transition metal element ^{M a (100mol%).} That the molar ratio of li / ^{M a} was synthesized were mixed so that 0.3 to 2.2, more preferably.
Specific examples of the transition metal oxide include (MA) a transition metal oxide having a layered rock salt type structure, (MB) a transition metal oxide having a spinel type structure, (MC) a lithium-containing transition metal phosphate compound, (MD) And (ME) lithium-containing transition metal silicate compounds.

(MA) As specific examples of the transition metal oxide having a layered rock salt type structure, LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate), LiNi _0.85 Co _0.10 Al 0.1 _{. 05} O ₂ (lithium nickel cobalt aluminum oxide [NCA]), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (lithium nickel manganese cobalt oxide [NMC]), LiNi _0.5 Mn _0.5 O ₂ ( Lithium manganese nickelate).
(MB) As specific examples of the transition metal oxide having a spinel structure, LiMn ₂ O ₄ (LMO), LiCoMnO ₄ , Li ₂ FeMn ₃ O ₈ , Li ₂ CuMn ₃ O ₈ , Li ₂ CrMn ₃ O _8, and Li 2 ₂ NiMn ₃ O ₈ .
Examples of (MC) lithium-containing transition metal phosphate compounds include olivine-type iron phosphates such as LiFePO ₄ and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as LiFeP ₂ O ₇ , and LiCoPO _4. And monoclinic nasicon-type vanadium phosphate salts such as Li ₃ V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate).
(MD) as the lithium-containing transition metal halogenated phosphate compound, for _example, Li 2 FePO ₄ F such fluorinated phosphorus iron _salt, Li 2 MnPO ₄ hexafluorophosphate manganese salts such as F and _Li 2 CoPO ₄ F And the like, such as cobalt fluorophosphates.
(ME) Examples of the lithium-containing transition metal silicate compound include Li ₂ FeSiO ₄ , Li ₂ MnSiO ₄ , and Li ₂ CoSiO ₄ .
In the present invention, a transition metal oxide having a (MA) layered rock salt type structure is preferable, and LCO or NMC is more preferable.

The shape of the positive electrode active material is not particularly limited, but is preferably particulate. The average particle size (sphere-converted average particle size) of the positive electrode active material is not particularly limited. For example, it can be 0.1 to 50 μm. The average particle diameter of the positive electrode active material particles can be measured in the same manner as the above-mentioned average particle diameter of the inorganic solid electrolyte. In order to make the positive electrode active material have a predetermined particle size, an ordinary pulverizer or a classifier is used as in the case of the negative electrode active material.
The positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

(4) The positive electrode active material may be surface-coated with the above-mentioned surface coating agent, sulfur or phosphorus, and further with the above-mentioned actinic ray or the like, similarly to the negative electrode active material.

The positive electrode composition may contain one kind of positive electrode active material, or may contain two or more kinds.
When the positive electrode active material layer is formed, the total mass (mg) (weight per unit area) of the positive electrode active material and the inorganic solid electrolyte per unit area (cm ² ) of the positive electrode active material layer is not particularly limited. It can be appropriately determined according to the designed battery capacity, for example, 1 to 100 mg / cm ² .

The content of the positive electrode active material in the positive electrode composition is not particularly limited, and is preferably from 10 to 97% by mass, more preferably from 30 to 95% by mass, and still more preferably from 40 to 93% by mass at a solid content of 100% by mass. , 50 to 90% by mass is particularly preferred.
When the positive electrode composition contains an inorganic solid electrolyte, the total content of the inorganic solid electrolyte and the positive electrode active material in the positive electrode composition is, in the negative electrode composition, the inorganic solid electrolyte and the negative electrode active material. It is preferable that it is in the same range as the total content.

(Positive electrode sheet for all solid state secondary batteries)
A positive electrode sheet for an all solid state secondary battery capable of forming a positive electrode active material layer of an all solid state secondary battery includes a positive electrode active material layer instead of a negative electrode active material layer, and further includes a positive electrode collector instead of a negative electrode current collector. It is the same as the negative electrode sheet for an all-solid secondary battery of the present invention, except that an electric conductor is appropriately provided. The layer thickness of each layer constituting the positive electrode sheet for an all-solid secondary battery is the same as the layer thickness of each layer described in the all-solid secondary battery described later. The content of each component in the positive electrode active material layer of the positive electrode sheet is not particularly limited, but is preferably synonymous with the content of each component in the solid content of the solid electrolyte composition (composition for positive electrode) of the present invention. is there.
The method for producing a positive electrode sheet for an all-solid secondary battery is also the same as the method for producing a negative electrode sheet for an all-solid secondary battery of the present invention, except that the above-mentioned composition for a positive electrode is appropriately used with a positive electrode current collector.

(Solid electrolyte composition)
The inorganic solid electrolyte layer of the all solid state secondary battery can be formed of, for example, a solid electrolyte composition or the like.
As the solid electrolyte composition, a known composition can be used without any particular limitation. For example, an inorganic solid electrolyte, preferably a binder, further a dispersion medium, a solid electrolyte composition containing other additives as appropriate, preferably, a solid electrolyte composition containing an inorganic solid electrolyte, a binder and a dispersion medium Is mentioned. The solid electrolyte composition usually does not contain an active material.
The solid electrolyte composition contains, as the inorganic solid electrolyte, the binder, the dispersion medium and the other additives, each can be used without particular limitation, and those in the negative electrode composition of the present invention. May be the same or different.

Among the binders contained in the solid electrolyte composition, as the binder different from the composition for the negative electrode of the present invention, various binders usually used for the solid electrolyte composition for an all-solid secondary battery can be applied without any particular limitation. For example, fluoropolymers, hydrocarbon-based thermoplastic polymers, (meth) acrylic polymers, copolymers with other vinyl monomers, polyurethane, polyurea, polyamide, polyimide, polyester, polyether, polycarbonate, cellulose Examples of the binder include various polymers such as derivative polymers.
Examples of the fluorine-containing polymer include polytetrafluoroethylene (PTFE), polyvinylene difluoride (PVdF), and a copolymer of polyvinylene difluoride and hexafluoropropylene (PVdF-HFP).
Examples of the hydrocarbon group-based thermoplastic polymer include polyethylene, polypropylene, styrene butadiene rubber (SBR), hydrogenated styrene butadiene rubber (HSBR), butylene rubber, acrylonitrile butadiene rubber, polybutadiene, and polyisoprene.
Examples of the (meth) acrylic polymer include various (meth) acrylic monomers, (meth) acrylamide monomers, and copolymers of two or more of these monomers (preferably, copolymers of acrylic acid and methyl acrylate). No.
In addition, copolymers with other vinyl monomers are also preferably used. Examples include a copolymer of methyl (meth) acrylate and styrene, a copolymer of methyl (meth) acrylate and acrylonitrile, and a copolymer of butyl (meth) acrylate, acrylonitrile and styrene. In the present specification, the copolymer may be any of a statistical copolymer and a periodic copolymer, and is preferably a block copolymer.
Examples of the (meth) acrylic polymer include a polymer described in JP-A-2015-088486. Examples of the polyurethane, polyurea, polyamide, and polyimide polymers include, for example, a polymer having a urethane bond, a polymer having a urea bond, a polymer having an amide bond, and a polymer having an imide bond described in JP-A-2015-088480. Polymers and the like.

The content of the binder, the dispersion medium, and the other additives in the solid electrolyte composition can be set in the same range as the content in the negative electrode composition of the present invention. The content of the inorganic solid electrolyte in the solid electrolyte composition is preferably 50% by mass or more and 100% by mass or more, and more preferably 70% by mass or more at a solid content of 100% by mass in view of dispersibility, reduction of interface resistance, and binding property. Is more preferable, and it is particularly preferable that it is 90 mass% or more. From the same viewpoint, the upper limit is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and particularly preferably 99% by mass or less.
For example, the solid electrolyte composition preferably has the same dispersion state and water content as the negative electrode composition of the present invention.
The solid electrolyte composition can be prepared in the same manner as the negative electrode composition.

(Solid electrolyte sheet for all-solid secondary battery)
The solid electrolyte sheet for an all-solid secondary battery capable of forming a solid electrolyte layer of an all-solid secondary battery may be a sheet having a solid electrolyte layer, even if the solid electrolyte layer is formed on a substrate, A sheet having no base material and formed from a solid electrolyte layer may be used. The solid electrolyte layer of the solid electrolyte sheet for an all-solid secondary battery can be obtained by forming the above-described solid electrolyte composition into a film in the same manner as the negative electrode composition. The configuration and thickness of the solid electrolyte layer of the sheet for an all-solid secondary battery are the same as the configuration and thickness of the solid electrolyte layer described in the all-solid secondary battery of the present invention. The solid electrolyte layer of the solid electrolyte sheet for an all-solid secondary battery is preferably formed of the solid electrolyte composition of the present invention. The content of each component in the solid electrolyte layer is not particularly limited, but preferably has the same meaning as the content of each component in the solid content of the solid electrolyte composition of the present invention. The solid electrolyte sheet for an all-solid secondary battery may have another layer described above in addition to the solid electrolyte layer.

(Manufacture of all-solid secondary batteries)
The all solid state secondary battery of the present invention includes a step of applying the composition for a negative electrode of the present invention on a base material (for example, a metal foil serving as a negative electrode current collector) and forming a coating film (forming a film). (Intermediate) method (the method for producing the sheet for an all solid state secondary battery of the present invention).
For example, the above-described composition for a positive electrode layer is applied on a metal foil as a positive electrode current collector to form a positive electrode active material layer, thereby producing a positive electrode sheet for an all-solid secondary battery. Next, for example, the solid electrolyte composition is applied on the positive electrode active material layer to form a solid electrolyte layer. Further, the composition for a negative electrode layer of the present invention is applied on the solid electrolyte layer to form a negative electrode active material layer. Obtaining an all-solid secondary battery with a structure in which a solid electrolyte layer is sandwiched between a positive electrode active material layer and a negative electrode active material layer by stacking a negative electrode current collector (metal foil) on the negative electrode active material layer Can be. This can be sealed in a housing to form a desired all-solid secondary battery.
In addition, by reversing the method of forming each layer, a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer are formed on the negative electrode current collector, and the positive electrode current collector is stacked to manufacture an all-solid secondary battery. You can also.

Another method is as follows. That is, as described above, the positive electrode sheet for an all-solid secondary battery and the negative electrode sheet for an all-solid secondary battery of the present invention are produced. Next, a solid electrolyte layer is formed on one of the active material layers of these sheets as described above. Further, the other of the positive electrode sheet for an all-solid secondary battery and the negative electrode sheet for an all-solid secondary battery of the present invention is laminated on the solid electrolyte layer so that the solid electrolyte layer and the active material layer are in contact with each other. Thus, an all-solid secondary battery can be manufactured.

Another method is as follows. That is, as described above, the positive electrode sheet for an all-solid secondary battery and the negative electrode sheet for an all-solid secondary battery of the present invention are produced. Separately, a solid electrolyte composition is applied on a substrate to prepare a solid electrolyte sheet for an all-solid secondary battery. Further, the positive electrode sheet for an all-solid secondary battery and the negative electrode sheet for an all-solid secondary battery are laminated so as to sandwich the solid electrolyte layer peeled off from the base material. Thus, an all-solid secondary battery can be manufactured.
Further, a positive electrode sheet for an all-solid secondary battery, a negative electrode sheet for an all-solid secondary battery, and a solid electrolyte sheet for an all-solid secondary battery are prepared as described above. Subsequently, the all-solid secondary battery positive electrode sheet or the all-solid secondary battery negative electrode sheet and the all-solid secondary battery solid electrolyte sheet were brought into contact with the positive electrode active material layer or the negative electrode active material layer and the solid electrolyte layer. In the state, it overlaps and pressurizes. Thus, the solid electrolyte layer is transferred to the positive electrode sheet for an all-solid secondary battery or the negative electrode sheet for an all-solid secondary battery. Thereafter, the solid electrolyte layer from which the base material of the solid electrolyte sheet for an all-solid secondary battery was peeled off and the negative electrode sheet for an all-solid secondary battery or the positive electrode sheet for an all-solid secondary battery were added (a negative electrode active material layer or The positive electrode active material layer is contacted (in a state of being in contact with the positive electrode active material layer) and pressurized. Thus, an all-solid secondary battery can be manufactured.

In the above manufacturing method, the composition for a negative electrode of the present invention or the negative electrode sheet for an all-solid secondary battery of the present invention is used for forming a negative electrode active material layer.
The solid electrolyte layer or the like can be formed by, for example, pressing a solid electrolyte composition or the like under pressure conditions described below on a substrate or an active material layer, or forming a sheet formed body of the solid electrolyte or the active material. It can also be used.

<Formation of each layer (film formation)>
The method for applying each composition such as the composition for a negative electrode of the present invention is not particularly limited and can be appropriately selected. Examples include coating (preferably wet coating), spray coating, spin coating, dip coating, slit coating, stripe coating, and bar coating.
At this time, each composition may be subjected to a drying treatment after being applied, or may be subjected to a drying treatment after being applied in a multilayer manner. The drying temperature is not particularly limited. The lower limit is preferably 30 ° C. or higher, more preferably 60 ° C. or higher, even more preferably 80 ° C. or higher. The upper limit is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and further preferably 200 ° C. or lower. By heating in such a temperature range, the dispersion medium can be removed, and a solid state (coated dry layer) can be obtained. Further, it is preferable because the temperature is not set too high and each member of the all solid state secondary battery is not damaged.

(4) As described above, when the composition for a negative electrode of the present invention is applied and dried, solid particles are firmly bound, and further, an applied dry layer having low interface resistance between solid particles can be formed.

It is preferable that each layer or the all-solid secondary battery is pressurized after preparing the applied composition or the all-solid secondary battery. It is also preferable to apply pressure in a state where the respective layers are stacked. Examples of the pressurizing method include a hydraulic cylinder press. The pressure is not particularly limited, and can be generally 5 MPa or more, preferably in the range of 50 to 1500 MPa.
Each of the applied compositions may be heated simultaneously with the application of pressure. The heating temperature is not particularly limited, and is generally in the range of 30 to 300 ° C. Pressing can be performed at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. On the other hand, when the inorganic solid electrolyte and the binder coexist, pressing can be performed at a temperature higher than the glass transition temperature of the polymer forming the binder. However, it is generally a temperature not exceeding the melting point of the polymer.
Pressurization may be performed in a state where the coating solvent or the dispersion medium is dried in advance, or may be performed in a state where the solvent or the dispersion medium remains.
In addition, each composition may be applied simultaneously, and the application and drying press may be performed simultaneously and / or sequentially. After coating on separate substrates, they may be laminated by transfer.

The atmosphere during pressurization is not particularly limited, and may be any of air, dry air (dew point −20 ° C. or less), inert gas (eg, argon gas, helium gas, and nitrogen gas).
As for the pressing time, a high pressure may be applied in a short time (for example, within several hours), or a medium pressure may be applied for a long time (one day or more). In the case of an all-solid secondary battery other than the all-solid secondary battery sheet, for example, in the case of an all-solid secondary battery, an all-solid secondary battery restraint (such as a screw tightening pressure) can be used to keep applying a moderate pressure.
The pressing pressure may be uniform or different with respect to a pressure-receiving portion such as a sheet surface.
The pressing pressure can be changed according to the area or the layer thickness of the pressed portion. The same part can be changed stepwise with different pressures.
The press surface may be smooth or rough.

In the method of transferring the solid electrolyte layer to the active material layer, the transfer conditions are not particularly limited, and the conditions described in the above “Formation of Each Layer (Film Formation)” can be applied.

<Initialization>
It is preferable that the all-solid-state secondary battery manufactured as described above be initialized after manufacturing or before use. The initialization is not particularly limited. For example, the initialization can be performed by performing initial charge and discharge in a state where the press pressure is increased, and then releasing the pressure until the general use pressure of the all solid state secondary battery is reached.

[Use of all-solid-state secondary battery]
The all solid state secondary battery of the present invention can be applied to various uses. There is no particular limitation on the application mode. For example, when mounted on an electronic device, a notebook computer, pen input computer, mobile computer, electronic book player, mobile phone, cordless phone handset, pager, handy terminal, mobile fax, mobile phone Copy, portable printer, headphone stereo, video movie, liquid crystal television, handy cleaner, portable CD, mini disk, electric shaver, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, etc. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game machines, road conditioners, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder fir machines, etc.). Furthermore, it can be used for various military purposes and space applications. Further, it can be combined with a solar cell.

本 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention should not be construed as being limited thereto. In the following examples, “parts” and “%” representing compositions are based on mass unless otherwise specified. In the present invention, “room temperature” means 25 ° C.

Each polymer having the composition shown in Table 1 was synthesized as follows.
1. Preparation example of binder dispersion or binder solution (Synthesis example of polymer)
[Synthesis Example 1: Preparation of binder dispersion S-1]
In a 200 mL three-necked flask, 1.33 g of a diol compound leading to the following component A-1 and 12.6 g of NISSO-PB GI-1000 (trade name, manufactured by Nippon Soda Co., Ltd.) were added, and dissolved in 71 g of THF (tetrahydrofuran). did. To this solution, 3.8 g of diphenylmethane diisocyanate was added, stirred at 60 ° C., and uniformly dissolved. 270 mg of Neostan U-600 (trade name, manufactured by Nitto Kasei Co., Ltd.) was added to the obtained solution, followed by stirring at 60 ° C. for 5 hours to obtain a viscous polymer solution. 0.6 g of methanol was added to the polymer solution to seal the terminal of the polymer, and the polymerization reaction was stopped to obtain a 20% by mass THF solution (polymer solution) of the polymer S-1.
Next, 96 g of heptane was added dropwise over 1 hour while stirring the polymer solution obtained above at 350 rpm to obtain an emulsion of the polymer S-1. This emulsion was heated at 85 ° C. for 120 minutes while flowing nitrogen. After the obtained residue, 50 g of heptane was added, and the mixture was further heated at 85 ° C for 60 minutes. This operation was repeated four times to remove THF. Thus, a 10% by mass heptane dispersion of a binder composed of the polymer S-1 was obtained.

[Synthesis Examples 2 to 16: Preparation of binder dispersions S-1 to S-15 and S-17]
In Synthesis Example 1, polymers S-1 to S-15 and polymers S-1 to S-15 were synthesized in the same manner as in Synthesis Example 1 except that the starting compounds for deriving the components shown in Table 1 were used in the amounts (mol%) shown in Table 1. Dispersions S-1 to S-15 and S-17 of a binder composed of S-17 were respectively prepared.

[Synthesis Example 17: Preparation of binder solution S-16]
In Synthesis Example 1, a solution S-16 of a polymer S-16 was prepared in the same manner as in Synthesis Example 1 except that the starting compounds for deriving the components shown in Table 1 were used in the amounts (mol%) shown in Table 1. Was prepared.

[Synthesis Examples 18 to 21: Preparation of Binder Dispersions T-1 to T-4]
In Synthesis Example 1, polymers T-1 to T-4 were prepared in the same manner as in Synthesis Example 1 except that the starting compounds for deriving the components shown in Table 1 were used in the amounts (mol%) shown in Table 1. Dispersions T-1 to T-4 were prepared respectively.

<Measurement of average particle size of particulate binder in binder dispersion>
For the binder dispersion, the average particle size of the particulate binder was measured in the same manner as in the method for measuring the average particle size of the inorganic solid electrolyte. Table 1 shows the results.
In the binder solution S-16, since the binder was dissolved in the dispersion, the average particle size could not be measured, and the result was described as "dissolved" in the table.

<Measurement of mass average molecular weight of polymer>
The mass average molecular weight of the synthesized polymer was measured by the above method (condition 2). Table 1 shows the results.

The constituent components of each of the above polymers are shown below, and a method for synthesizing a compound that leads to the constituent components will be described. In each structural formula, Me represents methyl.

[Reference Synthesis Example 1: Synthesis of diol compound leading to component A-6]
In a 200 mL three-necked flask, 35.3 g of α-thioglycerol (manufactured by Tokyo Chemical Industry) and 50.0 g of ethylene glycol monoacetoacetate monomethacrylate (manufactured by Tokyo Chemical Industry) were added and mixed. To this solution, 0.50 g of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred at room temperature for 4 hours to obtain a solution. This solution was diluted with 80 g of ethyl acetate, and washed once with 100 mL of water and five times with 150 mL of saturated saline. Sodium sulfate was added to the washed solution and dried, and after removing sodium sulfate by fold-fold filtration, the solvent was distilled off under reduced pressure. Thus, a diol compound leading to the component A-6 was obtained. The yield was 81%.

[Reference Synthesis Examples 2 to 7: Synthesis of Compounds Leading to Components A-1, A-2, A-4, A-5, A-7 and T-1]
In Reference Synthesis Example 1, component A- Diol compounds leading to 1, A-2, A-4, A-5, A-7 and T-1 were synthesized respectively.

[Reference Synthesis Example 8: Synthesis of diol compound leading to component A-3]
In a 3 L three-necked flask, 140 g of 2,2-bis (hydroxymethyl) butyric acid (manufactured by Tokyo Chemical Industry), 1400 g of acetone (manufactured by Wako Pure Chemical Industries), and pyridinium paratoluenesulfonate (manufactured by Wako Pure Chemical Industries) 1. 4 g was added to prepare a solution. The solution was heated at 60 ° C. with stirring for 1 hour. After cooling to room temperature, the solvent was distilled off to obtain a protected acetal of 2,2-bis (hydroxymethyl) butyric acid. The yield was 98%.
In a 500 mL three-necked flask, 20 g of the protected acetal, 45 g of methyl 12-hydroxystearate (manufactured by Wako Pure Chemical Industries), 23 g of dicyclohexylcarbodiimide (manufactured by Wako Pure Chemical Industries), and 4-dimethylaminopyridine (manufactured by Wako Pure Chemical Industries) 0.4 g was added and dissolved in 200 g of dichloromethane (manufactured by Wako Pure Chemical Industries, Ltd.). After heating this solution for 4 hours while stirring at room temperature, 200 mL of a 1M hydrochloric acid solution was added and stirred for 1 hour. This solution was washed twice with 100 mL of water and once with 150 mL of saturated saline. Sodium sulfate was added to the washed solution and dried, and after removing sodium sulfate by fold-fold filtration, the solvent was distilled off under reduced pressure. Thus, a diol compound leading to the component A-3 was obtained. The yield was 88%.

[Reference Synthesis Example 9: Synthesis of diol compound leading to constituent component T-3]
To a 1 L three-necked flask were added 50 g of glycerol (manufactured by Tokyo Chemical Industry), 500 g of acetone (manufactured by Wako Pure Chemical Industries), and 0.5 g of pyridinium paratoluenesulfonate (manufactured by Wako Pure Chemical Industries) to prepare a solution. The solution was heated at 60 ° C. with stirring for 1 hour. After cooling to room temperature, the solvent was distilled off to obtain a protected glycerol acetal. The yield was 99%.
In a 500 mL three-necked flask, 20 g of the above protected acetal, 32 g of methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 25 g of dicyclohexylcarbodiimide (manufactured by Wako Pure Chemical Industries, Ltd.), and 0.4 g of 4-dimethylaminopyridine (manufactured by Wako Pure Chemical Industries, Ltd.) In addition, it was dissolved in 200 g of dichloromethane (manufactured by Wako Pure Chemical Industries, Ltd.). After heating this solution for 4 hours while stirring at room temperature, 200 mL of a 1M hydrochloric acid solution was added and stirred for 1 hour. This solution was washed twice with 100 mL of water and once with 150 mL of saturated saline. Sodium sulfate was added to the washed solution and dried, and after removing sodium sulfate by fold-fold filtration, the solvent was distilled off under reduced pressure. Thus, a diol compound leading to the component T-3 was synthesized. The yield was 68%.

市販 A commercially available product (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used as the diol compound (methyl 2,2-bis (hydroxymethyl) butyrate) leading to the component T-2.

[Reference Synthesis Example 10: Synthesis of Macromonomer Leading to Component D-1]
190 parts by mass of toluene was added to a 1 L three-necked flask equipped with a reflux condenser and a gas introduction cock, nitrogen gas was introduced at a flow rate of 200 mL / min for 10 minutes, and the temperature was raised from room temperature to 80 ° C. A liquid (formulation α described below) prepared in a separate container was dropped into stirring toluene over 2 hours, and the mixture was stirred at 80 ° C for 2 hours. Thereafter, 0.2 parts by mass of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred at 95 ° C. for 2 hours. 0.025 parts by mass of 2,2,6,6-tetramethylpiperidine-1-oxyl (manufactured by Tokyo Chemical Industry Co., Ltd.) and glycidyl methacrylate (manufactured by Wako Pure Chemical Industries) were added to the solution kept at 95 ° C. after stirring. 13 parts by mass and 2.5 parts by mass of tetrabutylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, followed by stirring at 120 ° C. for 3 hours. After the obtained mixture was cooled to room temperature, it was added to methanol for precipitation. The precipitate was collected by filtration, washed twice with methanol, and dissolved by adding 300 parts by mass of heptane. The obtained solution was distilled off under reduced pressure to obtain a solution of macromonomer D-1. The solid content concentration was 40.1%, and the mass average molecular weight was 10,000. The structure of the obtained macromonomer D-1 is shown below.
(Prescription α)
Dodecyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 150 parts by mass Methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 59 parts by mass 3-mercaptopropionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) 2 parts by mass V-601 (Wako Pure Chemical Industries, Ltd.) 2.5 mass parts

The composition of each polymer in the binder dispersion or solution prepared as described above is shown in Table 1 below.
The components M1 to M4 shown in Table 1 are as follows.
The constituent component M1 is a constituent component represented by the above formula (I-1).
The constituent component M2 is a constituent component represented by the above formula (I-3) or (I-4), wherein ^RP2 is an aliphatic hydrocarbon group.
The constituent component M3 is a constituent component represented by the above formula (I-3) and has a specific side chain.
The constituent component M4 is a constituent component represented by the above formula (I-3), in which ^RP2 has the above-mentioned molecular chain.

In Table 1, “position” indicates the position of a carbon atom or a phosphorus atom of a carbonyl group, a thiocarbonyl group or a phosphoryl group in a side chain of the polymer. Specifically, in the longest molecular chain forming the side chain of the polymer, the number of connected atoms starting from an atom bonded to an atom constituting the main chain is shown. In the case where the compound has a plurality of the above carbonyl groups and the like, the number of the plurality of the bonds is also described through “/”.
In the column of “Component M4” in Table 1, “NISSO-PB GI1000 / PEG200” and “20/10” indicate that NISSO-PB GI1000 and PEG200 are used in combination at a content of 20 mol% and 10 mol%. Indicates that you were.
The binder dispersion T-3 uses an acrylic polymer as a polymer forming the binder. The components of the polymer are those corresponding to “Component M1” to “Component M4” in Table 1. Although not shown, for convenience, it is described in each component column of Table 1 in order.

<Abbreviation of table>
In the table, columns of the constituent components M1, M2 and M4 are represented by abbreviations of the names of the compounds that lead to the respective constituent units.
MDI: diphenylmethane diisocyanate H12 MDI: dicyclohexylmethane-4,4′-diisocyanate DGMEM: diethylene glycol monomethyl ether methacrylate HEOA: N, N′-bis (2-hydroxyethyl) oxamide DAB: 1,4-diaminobutane AEHS: monosuccinic acid (2-acryloyloxyethyl)
EGMEM: ethylene glycol monoacetoacetate monomethacrylate NISSO-PB GI1000: hydroxyl-terminated polybutadiene at both ends (mass average molecular weight: 1500, manufactured by Nippon Soda Co., Ltd.)
EPOL: hydroxyl-terminated liquid polyolefin (hydrogenated product of hydroxyl-terminated liquid polyisoprene, mass average molecular weight: 3300, manufactured by Idemitsu Kosan Co., Ltd.)
ODD: 1,18-octadecanediol PEG200: polyethylene glycol 200 (mass average molecular weight: 200, manufactured by Wako Pure Chemical Industries, Ltd.)
D-1: Macromonomer D-1 synthesized above

2. Synthesis of sulfide-based inorganic solid electrolyte Ohtomo, A .; Hayashi, M .; Tatsusumisago, Y .; Tsuchida, S .; Hama, K .; Kawamoto, Journal of Power Sources, 233, (2013), pp 231-235; Hayashi, S .; Hama, H .; Morimoto, M .; Tatsusumisago, T .; Minami, Chem. Lett. , (2001), pp872-873.
Specifically, in a glove box under an argon atmosphere (dew point -70 ° C.), 2.42 g of lithium sulfide (Li ₂ S, manufactured by Aldrich, purity> 99.98%) and diphosphorus pentasulfide (P ₂ S) were used. _5, Aldrich Co., purity> 99%) 3.90 g were weighed, charged into an agate mortar, using an agate pestle and mixed for 5 minutes. The mixing ratio of Li ₂ S and P ₂ S ₅ was Li ₂ S: P ₂ S ₅ = 75: 25 in molar ratio.
66 g of zirconia beads having a diameter of 5 mm were charged into a 45-mL zirconia container (manufactured by Fritsch), and the entire mixture of lithium sulfide and diphosphorus pentasulfide was charged therein, and the container was completely sealed under an argon atmosphere. A container was set in a planetary ball mill P-7 (trade name, manufactured by Fritsch), and mechanical milling was performed at a temperature of 25 ° C. and a rotation speed of 510 rpm for 20 hours to obtain a sulfide-based inorganic solid electrolyte (Li / P / S glass, hereinafter sometimes referred to as LPS.) 6.20 g was obtained. The average particle size was 2 μm.

[Example]
In this example, a negative electrode sheet for an all-solid secondary battery and an all-solid secondary battery having the layer configuration shown in FIG. 1 were prepared using the negative electrode composition prepared using the binder dispersion or the binder solution. To evaluate its performance. Table 2 shows the results.

<Preparation of composition for negative electrode>
(Preparation of Anode Active Material Layer Nos. 11 to 31 and c11 to c14)
180 zirconia beads having a diameter of 5 mm were put into a 250-mL zirconia container (manufactured by Fritsch), 20 g of the synthesized LPS, 2.0 g of a binder dispersion (binder solution) shown in Table 2 (in terms of solid content mass), And 48 g of the dispersion medium shown in Table 2. The container was set on a planetary ball mill P-7 (trade name) manufactured by Fritsch Inc., and stirred at 25 ° C. for 10 minutes at a rotation speed of 150 rpm. After that, 27 g of the negative electrode active material shown in Table 2 and further, carbon nanotubes VGCF (trade name, fiber diameter: 150 nm, manufactured by Showa Denko KK) as the conductive assistant were added at the contents (amount used) shown in Table 2, and again. The container was set in a planetary ball mill P-7, and mixing was continued at 25 ° C. and a rotation number of 100 rpm for 5 minutes. Thus, the composition for negative electrode No. 11 to 31 and c11 to c14 were prepared respectively.

(Preparation of Negative Electrode Active Material Layer Nos. 32 to 34)
Composition No. for negative electrode In the preparation of negative electrode composition No. 11, the content (use amount) of the solid electrolyte layer, the binder dispersion, the negative electrode active material and the conductive additive was changed to the values shown in Table 2. 11 in the same manner as in the preparation of negative electrode active material layer No. 11 32-34 were prepared respectively.

<Preparation of negative electrode sheet for all-solid secondary battery>
Each of the negative electrode compositions obtained above was applied on a copper foil (negative electrode current collector) having a thickness of 20 μm using a baker-type applicator (trade name: SA-201, manufactured by Tester Sangyo Co., Ltd.). The mixture was heated for a period of time to dry the negative electrode composition (removing the dispersion medium). Thereafter, the dried negative electrode composition (the dried layer coated with the negative electrode composition) was pressed at 25 ° C. (10 MPa, 1 minute) using a heat press machine to form a negative electrode active material layer having a layer thickness of 80 μm. Negative electrode sheet for all solid state secondary batteries 11 to 34 and c11 to c14 were produced, respectively.

<Preparation of solid electrolyte composition>
180 zirconia beads having a diameter of 5 mm were put into a 45 mL zirconia container (manufactured by Fritsch), and 4.85 g of LPS synthesized above, 0.15 g of polyvinylidene fluoride (PVdF, solid content conversion), and a dispersion medium And 16.0 g of heptane was charged. Thereafter, the container was set in a planetary ball mill P-7 (trade name) manufactured by Fritsch, and mixing was continued at a temperature of 25 ° C. and a rotation speed of 150 rpm for 10 minutes to prepare a solid electrolyte composition.
<Preparation of solid electrolyte sheet for all-solid secondary battery>
Next, each of the obtained solid electrolyte compositions was applied on a 20-μm-thick aluminum foil by the above-mentioned baker-type applicator, and heated at 80 ° C. for 2 hours to dry the solid electrolyte compositions. Thereafter, using a heat press machine, the dried solid electrolyte composition (the dried layer coated with the solid electrolyte composition) is heated and pressed at a temperature of 120 ° C. and a pressure of 600 MPa for 10 seconds, and the all solid secondary battery is heated. A solid electrolyte sheet for use was produced. The layer thickness of the solid electrolyte layer was 50 μm.

<Preparation of negative electrode sheet for solid-state secondary battery provided with solid electrolyte layer>
On the negative electrode active material layer of each of the prepared all-solid secondary battery negative electrode sheets, the above-prepared all-solid secondary battery solid electrolyte sheet was stacked so that the solid electrolyte layer was in contact with the negative electrode active material layer, and a press was used. After applying (pressing) at a temperature of 25 ° C. and a pressure of 50 MPa to transfer (stack) the solid electrolyte layer to the negative electrode sheet for an all-solid secondary battery, the pressure was further increased at a temperature of 25 ° C. and a pressure of 600 MPa. Thereafter, the aluminum foil of the solid electrolyte sheet was peeled off, and a negative electrode sheet for an all-solid secondary battery provided with a solid electrolyte layer having a layer thickness of 50 μm (a negative electrode sheet for an all-solid secondary battery with a solid electrolyte layer) No. 1 was obtained. 11 to 34 and c11 to c14 were produced, respectively. The thickness of the negative electrode active material layer of each sheet was 55 μm.

<Manufacture of all-solid secondary batteries>
Each of the prepared negative electrode sheets for an all-solid secondary battery with a solid electrolyte layer (the aluminum foil of the solid electrolyte sheet for an all-solid secondary battery was peeled off) was cut into a disc shape having a diameter of 14.5 mm, and FIG. As shown in the figure, the sheet is placed in a stainless steel 2032 type coin case 11 incorporating a spacer and a washer (not shown in FIG. 2), and a sheet-shaped NMC (LiNi _1/3 Co _1/3 Mn) is placed on the solid electrolyte layer. _1/3 O ₂ ) positive electrode layer (positive electrode active material layer, layer thickness 70 μm) was stacked. A stainless steel foil (positive electrode current collector) is further laminated thereon, and a laminate 12 for an all-solid-state secondary battery (a laminate composed of stainless steel foil-NMC positive electrode layer-solid electrolyte layer-negative electrode active material layer-copper foil) ) Formed. After that, by caulking the 2032 type coin case 11, the sample No. Test solid-state secondary batteries (coin batteries) 13 shown in FIG. 2 of Nos. 11 to 34 and c11 to c14 were produced, respectively. The test all solid state secondary battery 13 manufactured in this way has the layer configuration shown in FIG.

[Test Example 1: Evaluation of discharge capacity retention ratio]
The all-solid-state secondary battery No. produced as described above. With respect to 11 to 34 and c11 to c14, the discharge capacity retention ratio was measured to evaluate the cycle characteristics.
Specifically, the discharge capacity retention ratio of each all solid state secondary battery was measured by a charge / discharge evaluation device: TOSCAT-3000 (trade name, manufactured by Toyo System Co., Ltd.). Charging was performed at a current density of 0.1 mA / cm ² until the battery voltage reached 3.6 V. The discharge was performed at a current density of 0.1 mA / cm ² until the battery voltage reached 2.5 V. This one charge and one discharge was defined as one charge / discharge cycle, and three cycles of charge / discharge were repeated to initialize the all solid state secondary battery.
The initialized all-solid-state secondary battery was repeatedly charged and discharged under the same charging and discharging conditions as described above. When the discharge capacity (initial discharge capacity) in the first charge / discharge cycle after initialization is 100%, the number of charge / discharge cycles when the discharge capacity retention ratio (discharge capacity with respect to the initial discharge capacity) reaches 80% is as follows. The cycle characteristics were evaluated according to which of the following evaluation ranks was included.
In this test, the larger the number of charge / discharge cycles, the stronger the solid particles in the negative electrode active material layer were bonded to each other, and moreover, the solid particles and the negative electrode current collector were bonded. Is expressed), and the evaluation rank “D” or higher is a pass.

-Discharge capacity maintenance rate evaluation rank-
A: 500 cycles or more B: 300 cycles or more and less than 500 cycles C: 200 cycles or more and less than 300 cycles D: 100 cycles or more and less than 200 cycles E: 50 cycles or more and less than 100 cycles F: Less than 50 cycles
In addition, all solid-state secondary battery No. Each of the initial discharge capacities of 11 to 34 showed a value sufficient to function as an all-solid secondary battery.

[Test Example 2: Ion conductivity measurement]
Each of the negative electrode sheets for an all-solid secondary battery with a solid electrolyte layer prepared above (the aluminum foil of the solid electrolyte sheet for an all-solid secondary battery has been peeled off) is cut into two discs each having a diameter of 14.5 mm. Was. The solid electrolyte layers of the two disc-shaped sheets cut out are attached to each other to form a laminate for an all-solid-state secondary battery (copper foil-negative electrode active material layer-solid electrolyte layer-negative electrode active material layer-copper laminate ) 12 was produced. This all-solid-state secondary battery laminate 12 was placed in a stainless steel 2032 type coin case 11 incorporating a spacer and a washer (not shown in FIG. 2) as a test body for ion conductivity measurement. By caulking the 2032 type coin case 11, a test all-solid secondary battery 13 having a configuration shown in FIG. 2 and having been tightened with a force of 8 Newton (N) was produced.

The ionic conductivity was measured using the test all-solid secondary battery 13 obtained as the ionic conductivity measurement test body. Specifically, the AC impedance of the test all solid secondary battery 13 was measured in a thermostat at 30 ° C. using a 1255B FREQUENCY RESPONSE ANALYZER (trade name, manufactured by SOLARTRON) at a voltage amplitude of 5 mV and a frequency of 1 MHz to 1 Hz. did. Thereby, the resistance in the layer thickness direction of the bonded negative electrode sheet for an all-solid secondary battery with a solid electrolyte layer was obtained, and the ion conductivity was calculated by the following equation (1).

Formula (1): Ion conductivity σ (mS / cm) =
1000 × sample layer thickness (cm) / [resistance (Ω) × sample area (cm ² )]

In the formula (1), the sample layer thickness is measured before the all-solid-state rechargeable battery laminate 12 is put in the 2032-type coin case 11, and the value obtained by subtracting the thickness of the two copper foils (the solid electrolyte layer and the negative electrode). (Total thickness of active material layers). The sample area is the area of a disc-shaped sheet having a diameter of 14.5 mm.

It was determined which of the following evaluation ranks contained the obtained ion conductivity.
Regarding the ionic conductivity in this test, an evaluation rank “D” or higher passes.

-Ion conductivity evaluation rank-
A: 0.60 ≦ σ
B: 0.50 ≦ σ <0.60
C: 0.40 ≦ σ <0.50
D: 0.30 ≦ σ <0.40
E: 0.20 ≦ σ <0.30
F: σ <0.20

<Notes in the table>
In Table 2, "content" indicates the content (% by mass) of each component in the negative electrode composition, and the numerical value in parentheses indicates the content (% by mass) relative to 100% by mass of the solid component in the negative electrode composition. %).
<Abbreviation of table>
LPS: Li / P / S glass synthesized above LLT: Li _0.33 La _0.55 TiO ₃ (average particle size 3.25 μm, manufactured by Toshima Seisakusho)
Si: Si powder (APS: 1 to 5 μm, manufactured by Alfa Aesar)
Graphite: CGB20 (trade name, average particle size 20 μm, manufactured by Nippon Graphite Co., Ltd.)
Sn: Tin powder (average particle size 10 μm, manufactured by Aldrich)
VGCF: carbon nanotube (manufactured by Showa Denko KK)

The following can be seen from the results shown in Table 2.
Sample No. The binder used in c11 to c14 is a binder made of a polymer other than the polymer specified in the present invention. When these binders are used as the binder of the composition for the negative electrode, the ionic conductivity is low and the cycle characteristics are not sufficient.
Sample No. The binder used for c11 to c14 is, in order, a binder composed of a polymer having a structural unit having a carbonyl group (carboxy group) bonded to a hydroxy group, and a polymer having a structural unit having a carbonyl group bonded directly to the main chain. A binder made of a binder, a binder made of an acrylic polymer, and a binder made of a polymer containing a constituent unit having a carbonyl group at a position three atoms away from the atoms constituting the main chain.
On the other hand, when a binder made of the polymer specified in the present invention is used as a binder of the composition for a negative electrode, high ion conductivity is exhibited and cycle characteristics are excellent. Therefore, an all-solid-state secondary battery including the negative electrode active material layer formed using the negative electrode composition has characteristics of low battery resistance and high discharge capacity. In particular, even when silicon powder is used as the negative electrode active material, the discharge capacity retention rate can be significantly improved while effectively suppressing an increase in battery resistance.

Although the present invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and contradict the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted broadly without.

This application claims the priority based on Japanese Patent Application No. 2018-182798 filed in Japan on September 27, 2018, which is hereby incorporated by reference. Capture as a part.

DESCRIPTION OF SYMBOLS 1 Negative electrode current collector 2 Negative electrode active material layer 3 Solid electrolyte layer 4 Positive electrode active material layer 5 Positive electrode current collector 6 Operating part 10 All-solid secondary battery 11 Coin case 12 All-solid secondary battery laminate 13 All solids for test Secondary battery (Test body for measuring ion conductivity)

Claims

A negative electrode of an all-solid secondary battery including an inorganic solid electrolyte having ion conductivity of a metal belonging to Group 1 or 2 of the periodic table, a binder made of a polymer, a negative electrode active material, and a dispersion medium. A composition for
The polymer has at least one bond selected from the group consisting of an amide bond, a urea bond, and a urethane bond in a main chain, and
The following conditions A and B:
[Condition A] At least one group selected from the group consisting of a carbonyl group, a thiocarbonyl group, and a phosphoryl group is provided in a chain structure at least four atoms away from the atoms constituting the main chain. [Condition B] The group is A composition for a negative electrode, comprising a polymer having a constituent component having a side chain that is not bonded to a hydroxy group.
負極 The negative electrode composition according to claim 1, wherein the content of the constituent component in the polymer is 5 to 40% by mass.
In the components, the proportion of the total weight W G of the base relative to the total weight W S of the chain structure portion [W G / W S] is 0.05 or more, the composition for a negative electrode according to claim 1 or 2 Stuff.
負極 The negative electrode composition according to any one of claims 1 to 3, wherein the negative electrode active material is an active material that can be alloyed with lithium.
The negative electrode composition according to claim 4, wherein the active material capable of being alloyed with lithium is a silicon-based negative electrode active material containing a Si element as a constituent element.
The negative electrode composition according to any one of claims 1 to 5, wherein the side chain has a partial structure represented by any of the following formulas (I) to (III).

In the formula, L 1 to L 4 represent a linking group, and R 1 and R 2 represent a substituent.
The negative electrode composition according to any one of claims 1 to 6, wherein the binder is dispersed in the dispersion medium.
(8) The composition for a negative electrode according to any one of (1) to (7), further comprising a conductive additive.
The composition for a negative electrode according to any one of claims 1 to 8, wherein the inorganic solid electrolyte is a sulfide-based solid electrolyte.
A negative electrode sheet for an all-solid secondary battery having a negative electrode active material layer composed of the negative electrode composition according to any one of claims 1 to 9.
An all-solid secondary battery including a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order,
An all-solid secondary battery in which the negative electrode active material layer is a negative electrode active material layer composed of the negative electrode composition according to any one of claims 1 to 9.
A method for producing a negative electrode sheet for an all-solid secondary battery, comprising forming the negative electrode composition according to any one of claims 1 to 9 into a film.
A method for manufacturing an all-solid secondary battery, which manufactures an all-solid secondary battery through the manufacturing method according to claim 12.