JP6969004B2 - Solid electrolyte composition, solid electrolyte-containing sheet, electrode sheet for all-solid-state secondary battery and all-solid-state secondary battery - Google Patents

Description

The present invention relates to a solid electrolyte composition, a solid electrolyte-containing sheet, an electrode sheet for an all-solid-state secondary battery, and an all-solid-state secondary battery.

The lithium ion secondary battery is a storage battery having a negative electrode, a positive electrode, and an electrolyte sandwiched between the negative electrode and the positive electrode, and can be charged and discharged by reciprocating lithium ions between the two electrodes. Conventionally, an organic electrolytic solution has been used as an electrolyte in a lithium ion secondary battery. However, the organic electrolytic solution is liable to leak, and there is a possibility that a short circuit may occur inside the battery due to overcharging or overdischarging, resulting in ignition, and further improvement in safety and reliability is required.
Under such circumstances, an all-solid-state secondary battery using an inorganic solid electrolyte instead of the organic electrolyte has attracted attention. In the all-solid-state secondary battery, the negative electrode, the electrolyte, and the positive electrode are all solid, and the safety and reliability of the battery using the organic electrolytic solution can be greatly improved.

In such an all-solid secondary battery, an inorganic solid electrolyte, an active material, a binder (binder) and the like are contained as materials for forming a constituent layer such as a negative electrode active material layer, a solid electrolyte layer and a positive electrode active material layer. The material has been proposed.
For example, Patent Document 1 describes an inorganic solid electrolyte, an organic solvent, an average diameter of 0.001 to 1 μm, an average length of 0.1 to 150 μm, and a ratio of the average length to the average diameter. Contains a linear structure (specifically, cellulose, carbon, zinc oxide or titanium oxide nanofibers) having an electric conductivity of 10 to 100,000 and an electric conductivity of 1 × 10 ^{-6 S / m or less.} The solid electrolyte composition to be used is described. Further, in Patent Document 2, a lithium ion conductive solid electrolyte synthesized from a plurality of compounds containing at least lithium sulfide and a polymer elastic body (specifically, a fluororesin and a polyester resin) are dry-kneaded to obtain the obtained product. A solid electrolyte molded body obtained by molding the obtained mixture is described.

Patent Document 3 describes a non-aqueous secondary battery having an electrode as a negative electrode formed by adhering metal particles having an average particle size of 1 μm or less on a current collector with a binder (specifically, polyvinylidene fluoride). ing. It is described that the non-aqueous secondary battery using this electrode as a negative electrode has a higher capacity than the conventional graphite-based electrode material, and the decrease in capacity due to charging and discharging is small.

International Publication No. 2016/199805 Japanese Unexamined Patent Publication No. 6-76828 Japanese Unexamined Patent Publication No. 2000-12014

Since the constituent layer of the all-solid secondary battery is formed of solid particles such as an inorganic solid electrolyte, an active material if necessary, and a binder when a particulate binder is contained, a good interface state is maintained between the solid particles. Hard to form. For example, if the interfacial contact between the inorganic solid electrolyte and the active material is not sufficient, the interfacial resistance increases (ion conductivity and battery capacity decrease). Further, if the binding property between the solid particles is weak, the constituent layer does not have sufficient strength. Further, poor contact between solid particles occurs due to shrinkage and expansion of the constituent layer, particularly the active material layer, which accompanies the charging / discharging (release / absorption of lithium ions) of the all-solid-state secondary battery. In this way, the electrical resistance increases, and the battery performance rapidly decreases, resulting in a shortened battery life.
Moreover, in recent years, the development of all-solid-state secondary batteries has been rapidly progressing, and in addition to overcoming the above problems, further improvement of battery performance such as discharge capacity and discharge capacity density is required.

INDUSTRIAL APPLICABILITY The present invention suppresses an increase in interfacial resistance between solid particles in the obtained all-solid secondary battery by using it as a material for forming a constituent layer of the all-solid secondary battery, and firmly binds the solid particles. An object of the present invention is to provide a solid electrolyte composition capable of maintaining an excellent discharge capacity and discharge capacity density even after repeated charging and discharging. Another object of the present invention is to provide a solid electrolyte-containing sheet, an electrode sheet for an all-solid-state secondary battery, and an all-solid-state secondary battery having a layer composed of the solid electrolyte composition.

As a result of various studies, the present inventors have made a polymer satisfying a specific elastic modulus and elastic deformation rate, and have a specific size (average diameter D, average length L, and ratio of average length L to average diameter D). A solid electrolyte composition prepared by combining a fibrous binder forming the above) with an inorganic solid electrolyte and a dispersion medium has a high strength in which the solid particles are firmly bonded while suppressing the interfacial resistance between the solid particles. We have found that layers can be formed. Moreover, it has been found that an all-solid-state secondary battery provided with this layer as a constituent layer can maintain a high discharge capacity and a discharge capacity density even after repeated charging and discharging, and exhibits a good battery life. 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> Periodic table Inorganic solid electrolytes with ionic conductivity of metals belonging to Group 1 or Group 2
A binder made of a polymer satisfying the following properties (P1) and (P2), and a fibrous binder satisfying the following properties (B1) to (B3).
A solid electrolyte composition comprising a dispersion medium.
(P1) Elastic modulus: 0.1 to 1,000 MPa
(P2) Elastic deformation rate: 0.01 to 10,000%
(B1) Average diameter D: 0.001 to 10 μm
(B2) Average length L: 0.1 μm to 1,000 mm
(B3) Ratio of average length L to average diameter D L / D: 10 to 100,000
<2> The solid electrolyte composition according to <1>, wherein the polymer has at least one component containing an aliphatic hydrocarbon group having 5 or more carbon atoms.
<3> The solid electrolyte composition according to <1> or <2>, wherein the polymer has at least one functional group selected from the following functional group group (a).
Functional group (a)
Acidic functional group, basic functional group, hydroxy group, cyano group, alkoxysilyl group, aryl group, heteroaryl group, aliphatic hydrocarbon ring group having 3 or more rings condensed.

式中、Ｒ^１及びＲ^２は、水素原子；アルキル基；ポリエチレンオキシド鎖、ポリプロピレンオキシド鎖、ポリカーボネート鎖若しくはポリエステル鎖を含有する質量平均分子量が５０以上２００，０００以下の置換基；アルコール性水酸基、フェノール性水酸基、スルファニル基、カルボキシ基、スルホン酸基、リン酸基、ニトリル基、アミノ基、双性イオン含有基、若しくは、ヒドロキシ基若しくはアルコキシド基を有する金属化合物からなる基を有する１価の置換基；又は；炭素−炭素不飽和基を有する置換基を示す。
Ｒ^３は、炭化水素鎖；ポリエチレンオキシド鎖、ポリプロピレンオキシド鎖、ポリカーボネート鎖若しくはポリエステル鎖を含有する質量平均分子量が５０以上２００，０００以下の連結基；アルコール性水酸基、フェノール性水酸基、スルファニル基、カルボキシ基、スルホン酸基、リン酸基、ニトリル基、アミノ基、双性イオン含有基、若しくは、ヒドロキシ基若しくはアルコキシド基を有する金属化合物からなる基を有する連結基；又は；炭素−炭素不飽和基を有する連結基を示す。
Ｒ^４は芳香族若しくは脂肪族の連結基を示す。<4> The solid electrolyte composition according to any one of <1> to <3>, wherein the polymer has a constituent component represented by any of the following formulas (1-1) to (1-6).

In the formula, R ¹ and R ² are hydrogen atoms; an alkyl group; a substituent containing a polyethylene oxide chain, a polypropylene oxide chain, a polycarbonate chain or a polyester chain and having a mass average molecular weight of 50 or more and 200,000 or less; an alcoholic hydroxyl group. A monovalent substitution having a phenolic hydroxyl group, a sulfanyl group, a carboxy group, a sulfonic acid group, a phosphoric acid group, a nitrile group, an amino group, a twin ion-containing group, or a group consisting of a metal compound having a hydroxy group or an alkoxide group. Group; or; Indicates a substituent having a carbon-carbon unsaturated group.
R ³ is a hydrocarbon chain; a linking group containing a polyethylene oxide chain, a polypropylene oxide chain, a polycarbonate chain or a polyester chain and having a mass average molecular weight of 50 or more and 200,000 or less; an alcoholic hydroxyl group, a phenolic hydroxyl group, a sulfanyl group, a carboxy group. A linking group having a group consisting of a group, a sulfonic acid group, a phosphoric acid group, a nitrile group, an amino group, a twin ion-containing group, or a metal compound having a hydroxy group or an alkoxide group; or; a carbon-carbon unsaturated group. The linking group having is shown.
R ⁴ represents an aromatic or aliphatic linking group.

<5> The solid electrolyte composition according to any one of <1> to <4>, which contains an active material.
<6> The solid electrolyte composition according to <5>, wherein the active material is an active material that can be alloyed with lithium.
<7> The solid electrolyte composition according to any one of <1> to <6>, wherein the polymer has a glass transition temperature of −120 to 80 ° C.
<8> The solid electrolyte composition according to any one of <1> to <7>, wherein the inorganic solid electrolyte is a sulfide-based solid electrolyte.
<9> A solid electrolyte-containing sheet having a layer composed of the solid electrolyte composition according to any one of <1> to <8> above.
<10> An electrode sheet for an all-solid-state secondary battery having an active material layer composed of the solid electrolyte composition according to <5> or <6> above.
<11> An all-solid-state secondary battery including a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order.
The all-solid secondary layer in which at least one layer of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer is a layer composed of the solid electrolyte composition according to any one of <1> to <8>. battery.
<12> The all-solid-state secondary battery according to <11>, wherein the negative electrode active material layer is a layer composed of the solid electrolyte composition according to <5> or <6>.

The solid electrolyte composition of the present invention suppresses an increase in interfacial resistance between solid particles to firmly bind the solid particles, and provides a solid electrolyte layer capable of achieving excellent discharge capacity and discharge capacity density even after repeated charging and discharging. Can be formed. Therefore, the present invention suppresses an increase in interfacial resistance between solid particles in the obtained all-solid secondary battery by using it as a material for forming a constituent layer of the all-solid secondary battery, and firmly binds the solid particles. It is possible to provide a solid electrolyte composition capable of achieving an excellent discharge capacity and discharge capacity density even after repeated charging and discharging. It is possible to provide a solid electrolyte-containing sheet, an electrode sheet for an all-solid-state secondary battery, and an all-solid-state secondary battery having a layer composed of the solid electrolyte composition.
The above and other features and advantages of the present invention will become more apparent from the description below, with reference to the accompanying drawings as appropriate.

FIG. 1 is a vertical sectional view schematically showing an all-solid-state secondary battery according to a preferred embodiment of the present invention. FIG. 2 is a vertical sectional view schematically showing an all-solid-state secondary battery (coin battery) produced in the examples.

In the present invention, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
In the present invention, the term "acrylic" or "(meth) acrylic" simply means acrylic and / or methacryl.
In the present invention, the indication of a compound (for example, when referred to as a compound at the end) is used to mean that the compound itself, its salt, and its ion are included. In addition, it is meant to include a derivative which has been partially changed, such as by introducing a substituent, within the range of exhibiting a desired effect.
Substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) for which substitution or non-substitution is not specified in the present invention mean that the group may have an appropriate substituent. Therefore, even if it is simply described as a YYY group in the present specification, this YYY group includes a mode having a substituent in addition to a mode having no substituent. This is also synonymous with compounds that do not specify substitution or no substitution. Preferred substituents include substituent T, which will be described later.
In the present invention, when there are a plurality of substituents or the like designated by a specific reference numeral, or when a plurality of substituents or the like are specified simultaneously or selectively, the respective substituents or the like may be the same or different from each other. Means that. Further, even if it is not particularly specified, it means that when a plurality of substituents or the like are adjacent to each other, they may be linked to each other or condensed to form a ring.

In the present invention, the molecular weights of polymers and oligomers (including polymerized chains) refer to the mass average molecular weight in terms of standard polystyrene by gel permeation chromatography (GPC) unless otherwise specified. As the measuring method, the value measured by the method of the following condition 1 or condition 2 (priority) is basically used. However, an appropriate eluent can be appropriately selected depending on the type of polymer or the like.
(Condition 1)
Column: Connect two TOSOH TSKgel Super AWM-H (trade name, manufactured by Tosoh Corporation).
Carrier: 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: A column connected with TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, and TOSOH TSKgel Super HZ2000 (all trade names, manufactured by Tosoh Corporation) is used.
Carrier: Tetrahydrofuran Measurement temperature: 40 ° C
Carrier flow rate: 1.0 ml / min
Sample concentration: 0.1% by mass
Detector: RI (refractive index) detector

[Solid electrolyte composition]
The solid electrolyte composition of the present invention contains an inorganic solid electrolyte, the following fibrous binder, and a dispersion medium. This solid electrolyte layer composition is also referred to as an inorganic solid electrolyte-containing composition in that it contains an inorganic solid electrolyte described later.
The fibrous binder is a binder composed of a polymer satisfying the following properties (P1) and (P2), and has a fibrous shape satisfying the following properties (B1) to (B3) (in the present invention, simply , Sometimes called a fibrous binder.)
(P1) Elastic modulus: 0.1 to 1,000 MPa
(P2) Elastic deformation rate: 0.01 to 10,000%
(B1) Average diameter D: 0.001 to 10 μm
(B2) Average length L: 0.1 μm to 1,000 mm
(B3) Ratio of average length L to average diameter D: 10 to 100,000

In the solid electrolyte composition of the present invention, the inorganic solid electrolyte and the fibrous binder are in a dispersed state in which they are dispersed in a dispersion medium in a solid state.
When the fibrous binder is used as a constituent layer or a coated dry layer of a solid electrolyte composition described later, it connects solid particles such as an inorganic solid electrolyte, and further adjacent layers (for example, a current collector) to the solid particles. It suffices as long as it can be attached, and the solid particles do not necessarily have to be attached to each other in the above-mentioned dispersed state of the solid electrolyte composition. Further, the dispersed state (existing state) of the fibrous binder in the solid electrolyte composition is not particularly limited. For example, the dispersed state includes a state in which the fibrous binder is present (dispersed) alone in the solid electrolyte composition, a mode in which a plurality of fibrous binders are agglomerated or aggregated as a fibrous film, an inorganic solid electrolyte, and the like. Any of the states existing as a complex may be used, and these two or more states may be mixed. The fiber film preferably has a (three-dimensional) network structure, and examples thereof include a non-woven fabric (thin cotton-like, web-like) formed by overlapping or entwining a plurality of fibrous binders. The composite is not particularly limited, and for example, an embodiment in which the fibrous binder or the fibrous membrane is incorporated between the inorganic solid electrolytes (gap or interface), the fibrous binder or the fibrous membrane covers or surrounds the inorganic solid electrolyte. Examples thereof include an embodiment in which these coexist. When the solid electrolyte composition contains an active material or a conductive auxiliary agent, it is considered that the active material and the conductive auxiliary agent also form a complex in the same manner as the inorganic solid electrolyte.
The fibrous binder is formed of a polymer satisfying the above-mentioned properties (P1) and (P2), and may be formed of one molecule of the polymer, but usually several molecules of the polymer are bundled and formed into a fibrous form. ing.

When the solid electrolyte composition of the present invention contains an inorganic solid electrolyte, a fibrous binder, and a dispersion medium, the constituent layer formed of the solid electrolyte composition has an increase in interfacial resistance between solid particles (between solid particles). The contact resistance) can be suppressed and solid particles can be firmly bound, and the all-solid secondary battery having this constituent layer can maintain excellent discharge capacity and discharge capacity density even after repeated charging and discharging. The details of the reason are not clear yet, but it can be considered as follows.

As will be described later, the fibrous binder contained in the solid electrolyte composition of the present invention is a polymer satisfying the above-mentioned properties (P1) and (P2), and has a fibrous shape satisfying the above-mentioned properties (B1) to (B3). I am doing. Therefore, a structure (for example, the above-mentioned composite) in which a binder made of a polymer satisfying a specific elastic modulus and elastic deformation rate is bridged (bonded) between solid particles or between solid particles and a current collector is formed in the solid electrolyte composition. It is thought that it is formed by. As a result, in the constituent layer formed of this solid electrolyte composition, the solid particles are firmly bonded to each other, and when the constituent layer is formed on the current collector, the current collector and the solid particles are firmly bonded to each other. To wear. The all-solid-state secondary battery having the constituent layer with the improved film strength is formed of a polymer satisfying the above-mentioned characteristics (P1) and (P2) even if the constituent layer, particularly the active material layer, shrinks and expands due to charging and discharging. The resulting fibrous binder can follow this volume change well or absorb the volume change to maintain the bound state of the solid particles. It is considered that this can suppress an increase in electrical resistance and further shorten the battery life.
On the other hand, it is considered that the fibrous binder has an elongated shape as a fiber and also forms the above-mentioned complex with the above-mentioned fiber film and the solid particles even in the solid electrolyte layer. Therefore, it is possible to secure contact between the solid particles without excessively covering (adhering) the surface of the solid particles while maintaining the above-mentioned strong binding property. As a result, it is considered that the ion conduction path is maintained, the interfacial resistance between the solid particles can be suppressed low, and the discharge capacity (discharge capacity density) can be increased.
As described above, in the constituent layer composed of the solid electrolyte composition of the present invention, the contact state between the solid particles (the amount of the ionic conduction path constructed) and the binding force between the solid particles are improved in a well-balanced manner, and sufficient ions are obtained. It is considered that the solid particles and the like are bound to each other with strong binding property while constructing the conduction path, and the interfacial resistance between the solid particles is reduced. Each sheet or all-solid-state secondary battery provided with a constituent layer exhibiting such excellent characteristics exhibits a high discharge capacity (discharge capacity density) by suppressing an increase in electrical resistance, and further fills this high discharge capacity. Even if the discharge is repeated, it can be maintained.

The solid electrolyte composition of the present invention also includes an embodiment in which, as a dispersoid, an active material and, if necessary, a conductive auxiliary agent are contained in addition to the inorganic solid electrolyte (the composition of this embodiment is also referred to as an electrode composition. ). The solid electrolyte composition of the present invention follows or absorbs the volume change of the negative electrode active material (negative electrode active material layer) even if it contains a negative electrode active material having a large volume change due to charge and discharge, and is a solid particle. It is possible to maintain the bound state and the contact state of the above-mentioned, and exhibit the above-mentioned excellent action and effect. Therefore, the solid electrolyte composition of the present invention is one of the preferred embodiments containing the negative electrode active material.

The solid electrolyte composition of the present invention is a non-aqueous composition. In the present invention, the non-aqueous composition includes not only a water-free embodiment but also a water content (also referred to as a water content) of 50 ppm or less. In the non-aqueous composition, the water content is preferably 20 ppm or less, more preferably 10 ppm or less, and further preferably 5 ppm or less. The water content indicates the amount of water contained in the solid electrolyte composition (mass ratio to the solid electrolyte composition). The water content can be determined by filtering the solid electrolyte composition with a 0.45 μm membrane filter and performing Karl Fischer titration.

Hereinafter, the components contained in the solid electrolyte composition of the present invention and the components that can be contained will be described.

<Inorganic solid electrolyte>
In the present invention, the inorganic solid electrolyte is an inorganic solid electrolyte, and the solid electrolyte is a solid electrolyte capable of transferring ions inside the solid electrolyte. Since it does not contain organic substances as the main ionic conductive material, it is an organic solid electrolyte (polyelectrolyte represented by polyethylene oxide (PEO), organic represented by lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), etc.). It is clearly distinguished from (electrolyte salt). Further, since the inorganic solid electrolyte is a solid in a steady state, it is usually not dissociated or liberated into cations and anions. _{In this respect, it is also clearly distinguished from an electrolytic solution or an inorganic electrolyte salt (LiPF 6} , LiBF ₄ , LiFSI, LiCl, etc.) in which cations and anions are dissociated or released in the polymer. The inorganic solid electrolyte is not particularly limited as long as it has the ionic conductivity of a metal belonging to the first group or the second group of the periodic table, and generally does not have the electron conductivity.

In the present invention, the inorganic solid electrolyte has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table. As the inorganic solid electrolyte, a solid electrolyte material applicable to this type of product can be appropriately selected and used. For example, 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. Therefore, a sulfide-based inorganic solid electrolyte is preferable in terms of high ionic conductivity and ease of interparticle interface bonding.
When the all-solid-state secondary battery of the present invention is an all-solid-state lithium-ion secondary battery, it is preferable that the inorganic solid electrolyte has lithium ion ionic conductivity.

(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 Group 2 of the Periodic Table, and is electronically insulated. A compound having a property is preferable. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S and P as elements and has lithium ion conductivity, but other than Li, S and P may be used depending on the purpose or case. It may contain an element.

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

L _a1 M _b1 P _c1 S _d1 A _e1 equation (I)

In the formula, L represents an element selected from Li, Na and K, with Li being preferred. 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 satisfy 1 to 12:00 to 5: 1: 2 to 12:00 to 10. a1 is preferably 1 to 9, more preferably 1.5 to 7.5. b1 is preferably 0 to 3, more preferably 0 to 1. d1 is preferably 2.5 to 10 and more preferably 3.0 to 8.5. e1 is preferably 0 to 5, more preferably 0 to 3.

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

The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystallized (glass-ceramic), or only a part thereof may be crystallized. For example, Li-P-S-based glass containing Li, P and S, or Li-P-S-based glass ceramics containing Li, P and S can be used.
Sulfide-based inorganic solid electrolytes include, for example, lithium sulfide (Li ₂ S), phosphorus sulfide (for example, diphosphorus pentasulfide (P ₂ S ₅ )), simple phosphorus, simple sulfur, sodium sulfide, hydrogen sulfide, and lithium halide (eg, lithium halide). It can be produced by the reaction of at least two or more raw materials in the sulfides of the elements represented by LiI, LiBr, LiCl) and M (for example, SiS ₂ , SnS, GeS _2).

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 in this range, the lithium ion conductivity can be made high. Specifically, the lithium ion conductivity can be preferably 1 × 10 ^-4 S / cm or more, and more preferably 1 × 10 ^-3 S / cm or more. There is no particular upper limit, but it is practical that it is ^{1 × 10 -1 S / cm or less.}

As an example of a specific sulfide-based inorganic solid electrolyte, an example of combination of raw materials is 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 S-P ₂ S ₅ -P ₂ O ₅ , Li ₂ S-P ₂ S _5- SiS ₂ , Li ₂ S-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-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, such as _{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 room temperature is 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 Group 2 of the Periodic Table, and is electronically insulated. A compound having a property is preferable.
The oxide-based inorganic solid electrolyte preferably has an ionic conductivity of 1 × 10 ^-6 S / cm or more, more preferably 5 × 10 ^-6 S / cm or more, and 1 × 10 ^-5 S. It is particularly preferable that it is / cm or more. The upper limit is not particularly limited, but it is practical that it is ^{1 × 10 -1 S / cm or less.}

Specific examples of the compound include, for example, Li _xa La _ya TiO ₃ [xa = 0.3 to 0.7, ya = 0.3 to 0.7] (LLT), Li _xb La _yb Zr _zb M ^bb _mb O. _nb (M ^bb is at least one element of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, xb satisfies 5 ≦ xb ≦ 10, and yb is 1 ≦ yb. ≦ 4 is satisfied, zb is 1 ≦ zb ≦ 4, mb is 0 ≦ mb ≦ 2, nb is 5 ≦ nb ≦ 20), Li _{xc Byc} M ^cc _{zc Onc} (M ^cc is). At least one element of C, S, Al, Si, Ga, Ge, In, and Sn, xc satisfies 0 <xc ≦ 5, yc satisfies 0 <yc ≦ 1, and zc satisfies 0 <zc ≦. met 1, nc satisfies _{0 <nc ≦ 6.),} Li xd (Al, Ga) yd (Ti, Ge) zd Si ad P md O nd ( provided that, 1 ≦ xd ≦ 3,0 ≦ yd ≦ 1 , 0 ≦ zd ≦ 2,0 ≦ ad ≦ 1,1 ≦ md ≦ 7,3 ≦ nd ≦ 13), the number of ^{_{Li (3-2xe) M ee xe D}} ee O (xe 0 to 0.1 ^{represents, M ee} is ^{.D ee} representing the divalent metal atom represent a combination of halogen atom or two or more halogen _{atoms.), Li xf Si yf O} zf (1 ≦ xf ≦ 5,0 <yf ≦ 3 _{, 1 ≦ zf ≦ 10),} Li xg S yg O zg (1 ≦ xg ≦ 3,0 <yg ≦ 2,1 ≦ zg ≦ 10), 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), LISION (Lithium superionic compound) ) Li _3.5 Zn _0.25 GeO _{4 with} a perovskite type crystal structure, La _0.55 Li _0.35 TiO _{3 with a perovskite type crystal structure, LiTi 2} P ₃ with a NASICON (Naturium super ionic compound) type crystal structure. O ₁₂ , Li _{1 + xh + yh} (Al, Ga) _xh (Ti, Ge) _2-xh Si _yh P _3-yh O ₁₂ (however, 0 ≦ xh ≦ 1, 0 ≦ yh ≦ 1), Li having a garnet-type crystal structure ₇ La ₃ Zr ₂ O ₁₂ (LLZ) and the like can be mentioned. Phosphorus compounds containing Li, P and O are also desirable. For example, lithium phosphate (Li ₃ PO ₄ ), LiPON in which a part of oxygen of lithium phosphate is replaced with nitrogen, LiPOD ¹ (D ¹ is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr. , Nb, Mo, Ru, Ag, Ta, W, Pt, Au and the like (at least one selected from) and the like. Further, LiA ¹ ON (A ¹ is at least one selected from Si, B, Ge, Al, C, Ga and the like) and the like can also be preferably used.

(Iii) Halide-based inorganic solid electrolyte The halide-based inorganic solid electrolyte contains a halogen atom, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and is electronically insulated. A compound having a property is preferable.
The halide-based inorganic solid electrolyte is not particularly limited, and examples thereof include compounds such as Li 3 YBr ₆ and Li ₃ YCl ₆ described in LiCl, LiBr, LiI, ADVANCED MATERIALS, 2018, _{30, 1803075.} Of these, Li ₃ YBr ₆ and Li ₃ YCl ₆ are preferable.

(IV) Hydrogenated Inorganic Solid Electrolyte The hydride-based inorganic solid electrolyte contains a hydrogen atom, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and is electronically insulated. A compound having a property is preferable.
The hydride-based inorganic solid electrolyte is not particularly limited, and examples thereof include LiBH ₄ , Li ₄ (BH ₄ ) ₃ I, and 3LiBH _4- LiCl.

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, and more preferably 50 μm or less. The average particle size of the inorganic solid electrolyte is measured by the following procedure. Inorganic solid electrolyte particles are prepared by diluting a 1% by mass dispersion in a 20 mL sample bottle with water (heptane in the case of a water-unstable substance). The diluted dispersion sample is irradiated with 1 kHz ultrasonic waves for 10 minutes, and immediately after that, it is used for the test. Using this dispersion sample, data was captured 50 times using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA) using a measuring quartz cell at a temperature of 25 ° C. Obtain the volume average particle size. For other detailed conditions, etc., 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.

As the inorganic solid electrolyte, one type may be used alone, or two or more types may be used in combination.
The content of the inorganic solid electrolyte in the solid electrolyte composition is not particularly limited, but may be 50% by mass or more at 100% by mass of the solid content in terms of dispersibility, reduction of interfacial resistance and binding property. It is more preferably 70% by mass or more, and even more 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. However, when the solid electrolyte composition contains an active material described later, the content of the inorganic solid electrolyte in the solid electrolyte composition is the total content of the inorganic solid electrolyte and the active material.
In the present invention, the solid content (solid component) refers to a component that does not disappear by volatilizing or evaporating when the solid electrolyte composition is dried under a pressure of 1 mmHg and a nitrogen atmosphere at 150 ° C. for 6 hours. .. Typically, it refers to a component other than the dispersion medium described later.

<Fibrous binder>
The fibrous binder contained in the solid electrolyte composition of the present invention is a fibrous (high aspect ratio wire material) binder satisfying the following properties (B1) to (B3). When such a fibrous binder is used as the binder contained in the solid electrolyte composition, a layer having excellent contact state and binding force between solid particles can be formed, and excellent battery performance is maintained even after repeated charging and discharging. The effect that it can be an all-solid-state secondary battery can be obtained.
(B1) Average diameter D: 0.001 to 10 μm
(B2) Average length L: 0.1 μm to 1,000 mm
(B3) Ratio of average length L to average diameter D L / D: 10 to 100,000

The average diameter D of the fibrous binder is 0.001 to 10 μm, which is a higher level of the above effects (improvement of contact state and binding force between solid particles, and excellent battery performance when charging and discharging are repeated). It is preferably 0.005 to 5 μm, preferably 0.01 to 1 μm, more preferably 0.02 to 0.8 μm, and 0.1 to 0.5 μm. It is particularly preferable to have.
The average length L of the fibrous binder is 0.1 μm to 1,000 mm, and is preferably 0.5 μm to 100 mm, preferably 1 μm to 10 mm, in that the above effects can be achieved at a higher level. It is preferably 5 μm to 1 mm, more preferably 10 to 200 μm, and particularly preferably 10 to 200 μm.
The ratio L / D of the average length L to the average diameter D of the fibrous binder is 10 to 100,000, preferably 20 to 50,000 in that the above effect can be achieved at a higher level. , 30 to 10,000, more preferably 35 to 8,000, and particularly preferably 40 to 2,000.
In the present invention, the average diameter D, the average length L, and the ratio L / D may be independently within the ranges specified in the present invention, but the above ranges of the average diameter D and the average length L are the same. Each of the above ranges or each of the above ranges of the ratio L / D can be appropriately combined. Above all, in that the above effect can be achieved at a higher level, a combination of an average diameter D of 0.1 to 0.5 μm, an average length L of 10 to 200 μm, or a ratio L / D of 40 to 2000 μm is suitable. preferable.

The average diameter D and the average length L of the fibrous binder are measured as follows, and the ratio L / D is calculated from the obtained measured values.
That is, the average diameter D and the average length L are obtained by image processing an electron microscope image or an optical microscope image according to the size of the fibrous binder as follows. This measurement (observation) should be performed with the entire fibrous binder visible. Therefore, in addition to the measurement (observation) using an electron microscope, for example, when the average length L of the fibrous binder exceeds 100 μm, the measurement (observation) may be performed using an optical microscope or the like.
An aggregate of fibrous binders prepared from a polymer solution described later is observed in any three fields of view using a scanning electron microscope (SEM, XL30 (trade name), manufactured by PHILIPS) to obtain an SEM image. Each of these three field SEM images is converted into a BMP (bitmap) file, and 50 fibrous binders are used with "A-image-kun," which is an integrated application of IP-1000PC (trade name) manufactured by Asahi Engineering Co., Ltd. The fiber width (fiber diameter) and fiber length of each fibrous binder are read in a state where the entire fibrous binder is visible without overlapping in the image. Here, the fiber width of the fibrous binder is the average value of the fiber widths at five locations obtained by dividing the fiber length of one fibrous binder into four equal parts. Of the fibrous diameters of the 50 fibrous binders, the average value of 40 points excluding the upper and lower 5 points (5 points in order from the largest fiber diameter and 5 points in order from the smallest fiber diameter, totaling 10 points) was calculated. This average value is defined as the average diameter D of the fibrous binder. Similarly, out of the fiber lengths of the 50 fibrous binders, the average value of 40 points excluding the upper and lower 5 points is obtained, and this average value is defined as the average length L of the fibrous binder. The average length L thus obtained is divided by the average diameter D to calculate the ratio L / D of the average length L to the average diameter D.

When measuring the average diameter D, the average length L and the ratio L / D of the fibrous binder in the solid electrolyte composition or the constituent layer, it was taken out (extracted) from these compositions or the constituent layer as follows. The fibrous binder is the measurement target. The method for taking out the fibrous binder may be any method (condition) that does not cause a change in the size of the fibrous binder, and for example, a method of washing the composition or the constituent layer with a solvent used as a dispersion medium can be applied. At this time, a solvent that does not dissolve the fibrous binder is used.

The fibrous binder is formed of a polymer that satisfies the following properties (P1) and (P2). As described in Patent Documents 1 and 2, a binder made of a resin, an inorganic compound, or the like has usually been used in the solid electrolyte composition used in the all-solid-state secondary battery. However, as described above, solid particles can be obtained by using a polymer satisfying the following properties (P1) and (P2), which is not usually used as a material for forming a binder, and by using a fibrous binder having a specific size. It is possible to form an all-solid-state secondary battery that maintains a high discharge capacity (discharge capacity density) with low resistance even after repeated charging and discharging, by suppressing the increase in interfacial resistance between them to form a layer in which solid particles are firmly bonded. The effect is obtained.
A polymer satisfying the following properties (P1) and (P2) (in the present invention, it may be referred to as a binder-forming polymer for convenience) is difficult to be fibrous, and the binder for the solid particles is a polymer having a rigid structure such as cellulose. It is usually formed by. However, in the present invention, contrary to this, a binder-forming polymer satisfying the following characteristics (P1) and (P2) is used to form a fibrous material satisfying the above-mentioned characteristics (B1) to (B3).
(P1) Elastic modulus: 0.1 to 1,000 MPa
(P2) Elastic deformation rate: 0.01 to 10,000%

The elastic modulus of the binder-forming polymer is 0.1 to 1,000 MPa, preferably 0.5 to 800 MPa, and more preferably 1 to 600 MPa in that the above effects can be achieved at a higher level. , 10 to 500 MPa is more preferable, and 100 to 400 MPa is particularly preferable.
The elastic deformation rate of the binder-forming polymer is 0.01 to 10,000%, preferably 0.1 to 1,000%, preferably 1 to 100%, in that the above effects can be achieved at a higher level. It is more preferably 10 to 80%, and particularly preferably 15 to 50%.
In the present invention, the elastic modulus and the elastic deformation rate may be independently within the ranges specified in the present invention, but each of the above ranges of the elastic modulus and each of the above ranges of the elastic deformation rate may be appropriately combined. It is possible, and above all, a combination of an elastic modulus of 100 to 400 MPa and an elastic deformation rate of 15 to 50% is preferable.

The elastic modulus and elastic deformation rate of the binder-forming polymer are measured by performing a tensile test using the prepared test pieces as follows.
First, a test piece is prepared. That is, a solution of the binder-forming polymer, for example, a solution of the binder-forming polymer obtained by the synthesis method described later is applied onto a Teflon (registered trademark) sheet using a baker-type applicator (manufactured by Partech), and a blower dryer (manufactured by Paltec) is used. Let it stand in Yamato Kagaku) and dry at 200 ° C for 40 hours. Next, the polymer film after drying is specified by JIS K 7127 "Plastic-Test method for tensile properties Part 3: Test conditions for film and sheet" using a shopper type sample punching machine (manufactured by Yasuda Seiki Seisakusho). The standard test piece type 5 to be used is prepared.
Using the standard test piece type 5 thus obtained as a test piece, a tensile test is performed using a digital force gauge ZTS-5N and a vertical electric measuring stand MX2 series (both are trade names, manufactured by Imada Co., Ltd.). Two parallel marking lines 50 mm apart are attached to the center of the test piece, and the test piece is stretched at a speed of 10 mm per minute. JIS K 7161-1: 2014 "Plastic-How to determine tensile properties-First. The tensile elastic modulus (referred to as elastic modulus in the present invention) and the tensile yield strain (referred to as elastic deformation ratio in the present invention) are calculated based on "Part: General rule".

When measuring the elastic modulus and elastic deformation rate of the binder-forming polymer for the fibrous binder in the solid electrolyte composition or the constituent layer, the following is performed. That is, it can be measured by the above method by dissolving the fibrous binder in a solvent in which the binder-forming polymer is dissolved after taking out the fibrous binder according to the above-mentioned method for taking out the fibrous binder.

The glass transition temperature of the binder-forming polymer is not particularly limited, but is preferably −120 to 80 ° C., preferably −100 to 60 ° C. in terms of forming a shape according to the shape of the solid particles or the unevenness of the surface. Is more preferable, and the temperature is even more preferably −80 to 40 ° C.
The glass transition temperature (Tg) is measured using a dry sample and a differential scanning calorimeter "X-DSC7000" (trade name, manufactured by SII Nanotechnology) under the following conditions. The measurement is performed twice with the same sample, and the result of the second measurement is adopted.
Atmosphere in the measurement room: Nitrogen (50 mL / min)
Temperature rise rate: 5 ° C / min
Measurement start temperature: -100 ° C
Measurement end temperature: 200 ° C
Sample pan: Aluminum pan Weight of measurement sample: 5 mg
Calculation of Tg: Tg is calculated by rounding off the decimal point of the intermediate temperature between the descending start point and the descending end point of the DSC chart.
Regarding the fibrous binder in the solid electrolyte composition or the constituent layer, the glass transition temperature of the binder-forming polymer is, for example, put the composition or the constituent layer in water to disperse the contained components, and then filter. The remaining solid can be collected and measured by the above measurement method.

The mass average molecular weight of the binder-forming polymer is not particularly limited, but is preferably 5,000 or more, more preferably 10,000 or more, and particularly preferably 30,000 or more. The upper limit is preferably 1,000,000 or less, and more preferably 200,000 or less.

The binder-forming polymer is not particularly limited as long as it is a polymer satisfying the elastic modulus and elastic deformation rate, and various polymers can be applied. For example, sequential polymerization (hypercondensation, polyaddition or addition condensation) polymers such as polyurethane, polyurea, polyamide, polyimide, polyester, polyether, polycarbonate, etc., as well as fluoropolymers, hydrocarbon-based thermoplastic resins, vinyl polymers. , (Meta) acrylic polymer and the like. Examples of the hydrocarbon polymer include natural rubber, polybutadiene, polyisoprene, polystyrene butadiene, and hydrogenated (hydrogenated) polymers thereof. Of these, step-growth polymerization polymers are preferable, polyurethane, polyurea, polyamide or polyimide polymers are more preferable, polyurethane or polyurea are even more preferable, and polyurethane is particularly preferable.

In the present invention, the main chain of a polymer means a linear molecular chain in which all other molecular chains constituting the polymer can be regarded as a branched chain or a pendant with respect to the main chain. Although it depends on the mass average molecular weight of the molecular chain regarded as a pendant, the longest chain among the molecular chains constituting the polymer is typically the main chain. However, the functional group possessed by the polymer terminal is not included in the main chain. Further, the side chain of the polymer means a molecular chain other than the main chain, and includes a short molecular chain and a long molecular chain.

The above-mentioned polymers as the binder-forming polymer are not particularly limited as long as the above-mentioned properties (P1) and (P2) are satisfied, and each known polymer can be used, or an appropriately synthesized polymer can also be used.
The binder-forming polymer preferably has a constituent component represented by any of the following formulas (1-1) to (1-6), and is selected from the constituent components represented by the following formula according to the type of polymer. It may have two or more kinds (preferably 2 to 8 kinds) of constituents. The preferred combination of the constituents is not particularly limited, and examples thereof include combinations capable of forming the above-mentioned preferred type of binder-forming polymer. One kind of constituent in the combination of constituents means the number of kinds of constituents represented by any one of the following formulas, and has two kinds of constituents represented by one of the following formulas. However, it is not interpreted as two kinds of constituents.

In the formula (1-1), R ¹ and R ² are hydrogen atoms, alkyl groups (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 3 carbon atoms), and specific chains, respectively. Indicates a substituent having a mass average molecular weight of 50 or more and 200,000 or less, a substituent having a specific group (heteroatom-containing group), or a substituent having a carbon-carbon unsaturated group.
Substituents containing a specific chain and having a mass average molecular weight of 50 or more and 200,000 or less are substituents containing a polyethylene oxide chain, polypropylene oxide chain, polycarbonate chain or polyester chain having a mass average molecular weight of 50 or more and 200,000 or less. Is. The mass average molecular weight of this substituent is preferably 500 or more, more preferably 700 or more, still more preferably 1,000 or more. The upper limit is preferably 100,000 or less, more preferably 10,000 or less. Examples of the polycarbonate chain or the polyester chain include known chains made of polycarbonate or polyester.
The substituent preferably has an alkyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms) at the terminal. Further, the alkyl group may have an ether group (-O-), a thioether group (-S-), a carbonyl group (> C = O) or an imino group (> NR ^N ). ^RN represents a hydrogen atom or an alkyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 3 carbon atoms).

The monovalent substituent having a specific group, alcoholic hydroxyl group, phenolic hydroxyl group, a sulfanyl group, a carboxy group, a sulfonic acid group (sulfo group: _-SO 3 H), phosphoric acid group (phospho group: -OPO (OH ) ₂ etc.), a monovalent substituent having a group consisting of a nitrile group, an amino group, a twin ion-containing group, or a metal compound having a hydroxy group or an alkoxide group. In the present invention, the substituent having a specific group may be a substituent consisting of only a specific group or a substituent having a specific group and a linking group. The linking group is not particularly limited, and examples thereof include a group obtained by removing a predetermined number of hydrogen atoms from the substituent T described later.
Amino group is represented by -N ^(R _{N) 2,} is ^{R N} is as described above. Specifically, the zwitterion-containing group has a betaine structure (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms), and the cation portion includes each cation such as quaternary ammonium, sulfonium, or phosphonium. The anion portion includes each anion such as carboxylate or sulfonate. The group composed of a metal compound having a hydroxy group is not particularly limited, and examples thereof include a hydroxylsilyl group and a hydroxyltitanyl group. The group composed of a metal compound having an alkoxydo group is not particularly limited, and for example, an alkoxysilyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms) and an alkoxytitanyl group (1 to 12 carbon atoms are preferable). 1 to 6 are more preferable), and more specifically, a trimethoxysilyl group, a methyldimethoxysilyl group, a triethoxysilyl group, a methyldiethoxysilyl group, and a trimethoxytitanyl group can be mentioned.
The substituent having an alcoholic hydroxyl group is not particularly limited, and examples thereof include a hydroxyalkyl group (preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms). The substituent having a phenolic hydroxyl group is not particularly limited, and examples thereof include a hydroxyphenyl group.

Examples of the carbon-carbon unsaturated group in the substituent having a carbon-carbon unsaturated group include a carbon-carbon double bond or a carbon-carbon triple bond. Specific examples of the substituent having a carbon-carbon double bond include an acrylic group, a methacrylic group, a vinyl group, an allyl group, a maleimide group and the like. Specific examples of the substituent having a carbon-carbon triple bond include an ethynyl group and a propargyl group.

R ³ is a hydrocarbon chain, a specific weight average molecular weight containing chains 50 200,000 The following linking groups, linking group having a specific group (hetero atom-containing group), or a carbon - carbon unsaturated group Indicates a linking group having.

The ^{hydrocarbon chain that can be taken as R 3} means a chain of hydrocarbons (preferably oligomers or polymers) composed of carbon atoms and hydrogen atoms, and more specifically, a compound composed of carbon atoms and hydrogen atoms. It means a structure in which at least two atoms (for example, a hydrogen atom) or a group (for example, a methyl group) are desorbed. Terminal groups that may have at the end of the hydrocarbon chain shall not be included in the hydrocarbon chain. The hydrocarbon chain is preferably a chain having a structure in which at least two repeating units are connected (including an alkylene group, an alkynylene group, and the like). Further, the hydrocarbon chain is preferably composed of 50 or more carbon atoms. The mass average molecular weight of the hydrocarbon chain is not particularly limited, but is preferably 100 or more and less than 1,000,000, more preferably 300 or more and less than 100,000, and further preferably 500 or more and less than 10,000.
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, examples of the hydrocarbon chain include hydrocarbon chains composed of hydrocarbons selected from aliphatic hydrocarbons and aromatic hydrocarbons, and hydrocarbon chains composed of aliphatic hydrocarbons are preferable. The hydrocarbon chain preferably does not have a ring structure in its main chain, and more preferably a straight chain or a branched chain of an aliphatic hydrocarbon. The hydrocarbon chain is preferably a chain made of an elastomer, specifically, each chain of a diene-based elastomer having a double bond in the main chain and a non-diene-based elastomer having no double bond in the main chain. Can be mentioned. Examples of the diene-based elastomer include styrene-butadiene rubber (SBR), styrene-ethylene-butadiene rubber (SEBR), butyl rubber (IIR), butadiene rubber (BR), isoprene rubber (IR), and ethylene-propylene-diene rubber. Can be mentioned. Examples of the non-diene-based elastomer include olefin-based elastomers such as ethylene-propylene rubber and styrene-ethylene-butylene rubber, and hydrogen-reduced elastomers of the above-mentioned diene-based elastomers.
The hydrocarbon to be a hydrocarbon chain preferably has a reactive group at its terminal, and more preferably has a polycondensable terminal reactive group. The polycondensation or polyaddition-capable terminal reactive group forms a group bonded to ^{R 3} or R ⁴ of each of the above formulas by polypolymerization or polyaddition. Examples of such a terminal reactive group include an isocinate group, a hydroxy group, a carboxy group, an amino group, an acid anhydride and the like, and a hydroxy group is preferable.
Hydrocarbons having terminal reactive groups include, for example, NISSO-PB series (manufactured by Nippon Soda), Claysol series (manufactured by Tomoe Kosan), PolyVEST-HT series (manufactured by Ebonic), all of which have trade names. Poly-bd series (manufactured by Idemitsu Kosan Co., Ltd.), poly-ip series (manufactured by Idemitsu Kosan Co., Ltd.), EPOL (manufactured by Idemitsu Kosan Co., Ltd.), Polytail series (manufactured by Mitsubishi Chemical Corporation) and the like are preferably used.

A specific chain having a linking group containing a specific chain and having a mass average molecular weight of 50 or more and 200,000 or less, which can be taken as R ^{3, has a valence of divalent (removes one more hydrogen atom).} Is synonymous with a substituent containing a specific chain and having a mass average molecular weight of 50 or more and 200,000 or less, which can be taken as ^{R 1} and R ^{2, and the preferred range is also the same.}
The linking group having a specific group, which can be taken as ^{R 3} , is a substituent having a specific group (heteroatom-containing group), which can be taken as ^{R 1} and R ^{2, except that the valence is divalent.} It is synonymous and the preferred range is the same.
The linking group having a carbon-carbon unsaturated group, which can be taken as ^{R 3} , is the substituent having a carbon-carbon unsaturated group, which can be taken as ^{R 1} and R ^{2, except that the valence is divalent.} It is synonymous and the preferred range is the same.

The constituent component represented by any of the formulas (1-1) to (1-5) is preferably a constituent component having a long-chain linear group or a long-chain branched group, and is preferably a component having a long-chain linear group or a long-chain branched group, and is preferably the component having a long-chain linear group or a long-chain branched group. in to formula (1-5), the weight average molecular weight containing the aforementioned specific chain as ^{R 3} is more preferably a component take a linking group of 50 or more to 200,000 or less.

The constituent component represented by each of the above formulas may be a constituent component consisting of only the partial structure represented by each of the above formulas, or may be a constituent component including the partial structure represented by each of the above formulas. For example, when the binder-forming polymer is polyurethane or the like, it has a constituent component in which a carbonyl group is bonded to both nitrogen atoms of the partial structure represented by the above formula (1-4) or formula (1-5).

Wherein (1-6), ^{R 4} represents an aromatic or aliphatic linking group (tetravalent), preferred linking group represented by any one of the following formulas (i) ~ (iix).

In formulas (i) to (iix), X ¹ represents a single bond or a divalent linking group. As the divalent linking group, an alkylene group having 1 to 6 carbon atoms (for example, methylene, ethylene, propylene) is preferable. As propylene, 1,3-hexafluoro-2,2-propanediyl is preferable. L indicates −CH ₂ = CH ₂ − or −CH ₂ −. ^RX and ^RY represent hydrogen atoms or substituents, respectively. In each formula, * indicates the binding site with the carbonyl group in the formula (1-6). The substituents can take as R ^X and ^{R Y,} but is not particularly limited, and a substituted group T which will be described later, the number of alkyl group (carbon, preferably 1 to 12, more preferably 1 to 6, 1-3 More preferably) or an aryl group (preferably 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, still more preferably 6 to 10 carbon atoms).

The (total) content of the constituents represented by the above formula in the binder-forming polymer is not particularly limited, but is preferably 5 to 100% by mass, more preferably 10 to 100% by mass, and 50. It is more preferably ~ 100% by mass. The upper limit of the content may be, for example, 90% by mass or less regardless of the above 100% by mass.

The binder-forming polymer has a constituent component containing an aliphatic hydrocarbon group having 5 or more carbon atoms, which exhibits hydrophobicity and exhibits high affinity for solid particles, and disperses the solid particles in the solid electrolyte composition. It is preferable in that it can improve the properties. As the aliphatic hydrocarbon group, a group obtained by removing a hydrogen atom from an alkane (alkyl group or alkylene group) or a group obtained by removing a hydrogen atom from an alkene (alkenyl group or alkenylene group) is preferable, and a hydrocarbon having an ethylenically unsaturated bond is preferable. A group (hydrocarbon polymer chain) from which a hydrogen atom has been removed from a hydrogen polymer is more preferable. The aliphatic hydrocarbon group may be incorporated into the main chain of the binder-forming polymer or may be incorporated as a side chain. When incorporated into the main chain, this component is a component derived from a compound having a functional group at the end of an aliphatic hydrocarbon group, and is, for example, of the above formulas (1-2) to (1-6). Examples include the constituents represented by either.
The aliphatic hydrocarbon group may have 5 or more carbon atoms, but 8 or more is preferable and 10 or more is more preferable in terms of affinity with solid particles. The upper limit is not particularly limited and may be, for example, 100,000 or less. When the aliphatic hydrocarbon group is a hydrocarbon polymer chain, its mass average molecular weight is not particularly limited as long as it satisfies the above carbon number.
The constituent component containing the aliphatic hydrocarbon group having 5 or more carbon atoms may be different from the constituent component represented by any of the formulas (1-1) to (1-6). Those corresponding to the constituents represented by any of the formulas (1-1) to (1-6) are also preferable.
The 5 or more aliphatic hydrocarbon group having a carbon monovalent group obtained by removing one hydrogen atom from the hydrocarbon constituting the hydrocarbon chain can take as R ³ above are preferably exemplified.

The component containing an aliphatic hydrocarbon group having 5 or more carbon atoms preferably has at least one in the binder-forming polymer molecule, more preferably 2 to 1,000, and 3 to 1,000. It is more preferable to have 500 pieces. The (total) content in the binder-forming polymer is not particularly limited, but is preferably 0 to 80% by mass, more preferably 0.5 to 70% by mass, and 1 to 60% by mass. Is even more preferable. When the binder-forming polymer is polyurethane, the lower limit of this content can be 30% by mass regardless of the above values. Regardless of the above description, the upper limit of the content may be 100% by mass.

The binder-forming polymer may have components other than the above-mentioned components. In this case, the content in the binder-forming polymer is not particularly limited, but is preferably 80% by mass or less.

Examples of the constituent components other than the above-mentioned constituent components include appropriate constituent components capable of forming a polymer depending on the polymer type of the binder-forming polymer. For example, the components represented by the following formula (2), the above equation (1-2) to (1-5) Each component was changed ^{R 3} to ^{R P1} in formula (2) in such Can be mentioned. The content of these constituents in the binder-forming polymer is not particularly limited, and is appropriately determined according to the content of the constituents represented by the above formulas. For example, it can be 80% by mass or less, preferably 20 to 70% by mass, and is set to a content of 100% by mass in total with the content of the constituents represented by the above formulas. You can also.

In the formula, ^RP1 represents a hydrocarbon chain having a molecular weight of 20 or more. The molecular weight of the hydrocarbon chain cannot be uniquely determined because it depends on the type and the like, but for example, 30 or more is preferable, 50 or more is more preferable, 100 or more is further preferable, and 150 or more is particularly preferable. The upper limit is not particularly limited and can be set as appropriate, for example, 10,000 or less. The molecular weight of the hydrocarbon chain is measured for the raw material compound before it is incorporated into the main chain of the polymer.

Hydrocarbon chain which can be taken as R ^P1 denotes a chain of formed hydrocarbons from carbon and hydrogen atoms, more specifically, at least two atoms of a compound composed of carbon and hydrogen atoms (e.g. It means a structure in which a hydrogen atom) or a group (for example, a methyl group) is desorbed. However, in the present invention, the hydrocarbon chain also includes a chain having a group containing an oxygen atom, a sulfur atom or a nitrogen atom in the chain, for example, a hydrocarbon group represented by the following formula (M2). Terminal groups that may have at the end of the hydrocarbon chain shall not be included in the hydrocarbon chain. This 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 selected from an aliphatic hydrocarbon and an aromatic hydrocarbon.

Such a hydrocarbon chain is a chain composed of a normal (non-polymerizable) hydrocarbon group, and examples of the hydrocarbon group include an aliphatic or aromatic hydrocarbon group, and specific examples thereof. The alkylene group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, further preferably 1 to 6 carbon atoms) and the arylene group (preferably 6 to 22 carbon atoms, preferably 6 to 14 carbon atoms, 6 to 6 to 6). 10 is more preferable), or a group consisting of a combination thereof is preferable.

The aliphatic hydrocarbon group is not particularly limited, and is, for example, from a hydrogen-reduced product of an aromatic hydrocarbon group represented by the following formula (M2), or a partial structure of a known aliphatic diisosoane compound (for example, from isophorone). Narumoto) and the like.
As the aromatic hydrocarbon group, for example, a phenylene group or a hydrocarbon group represented by the following formula (M2) is preferable.

In the formula (M2), X represents a single bond, −CH ₂ −, −C (CH ₃ ) ₂ −, −SO ₂ −, −S−, −CO− or −O−, and is a viewpoint of binding property. Therefore, -CH _2- or -O- is preferable, and -CH _2- is more preferable. The above-mentioned alkylene group and alkylene group exemplified here may be substituted with a substituent T, preferably a halogen atom (more preferably a fluorine atom).
R ^M2 to R ^M5 each represents a hydrogen atom or a substituent, preferably a hydrogen atom. Examples of the substituent that can be taken as R ^M2 to R ^M5, is 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 or an aryl group having 6 to 10 carbon atoms having 1 to 20 carbon atoms.), a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom) Can be mentioned. The −N ( ^RM6 ) ₂ is an alkylamino group (preferably 1 to 20 carbon atoms, more preferably 1 to 6 carbon atoms) or an arylamino group (preferably 6 to 40 carbon atoms, 6 to 20 carbon atoms). More preferred).
Examples of the constituent component represented by the above formula (2) include a constituent component derived from the "diisocyanate compound" described in JP-A-2015-08480, which is incorporated herein by reference.

The binder-forming polymer has the above-mentioned formulas (1-1) to (1-6), components containing an aliphatic hydrocarbon group having 5 or more carbon atoms, and components other than these (for example, the following formula (2). ) Is appropriately contained. For example, polyurethanes, components represented by the following formula (2), the components were changed ^{R 3} to ^{R P1} in formula (2) in the above equation (1-2), the above equation (1 -2) Appropriately has the constituent components represented by 2). Further, the polyimide has a component represented by the following formula (1-5), a component represented by the following formula (1-6), and the like (however, 2 of the components represented by one of the formulas). Exclude one N). Polycarbonate has a configuration component represented by the above formula (1-2) as a constituent or R ³ is represented by the above formula of introducing oxygen atom at both ends of the R ³ (1-3) Formula ( It has a component represented by 1-3), a component represented by the above formula (1-2), a component obtained ^{by changing R 3} to RP ¹ , and the like.

The polyurethane, polyurea, polyamide, and polyimide polymers that can be used as the binder-forming polymer are not particularly limited as long as they satisfy the above-mentioned properties (P1) and (P2), but are described in, for example, JP-A-2015-08480. Examples thereof include a polymer having a urethane bond, a polymer having a urea bond, a polymer having an amide bond (polyamide resin), and a polymer having an imide bond.

When the binder-forming polymer has at least one functional group selected from the following functional group group (a), it can exhibit high binding property to solid particles and can bond solid particles to each other more firmly. In that respect, it is preferable. This functional group may be contained in the main chain or the side chain.
Functional group (a)
Acidic functional group, basic functional group, hydroxy group, cyano group, alkoxysilyl group, aryl group, heteroaryl group, aliphatic hydrocarbon ring group having 3 or more rings condensed.

The functional groups (adsorbable functional groups on the surface of the inorganic particles) of the binder-forming polymer are chemically or physically mutual with the surface of the inorganic solid electrolyte in the solid electrolyte composition, optionally coexisting active material or conductive auxiliary agent. It works. This interaction is not particularly limited, but is, for example, due to a hydrogen bond, an acid-base ionic bond, a covalent bond, a π-π interaction due to an aromatic ring, or a hydrophobic-hydrophobic interaction. Things etc. can be mentioned. When the functional groups interact, the chemical structure of the functional groups may or may not change. For example, in the above-mentioned π-π interaction or the like, the functional group usually does not change and the structure as it is is maintained. On the other hand, in an interaction due to a covalent bond or the like, an active hydrogen such as a carboxylic acid group is usually released as an anion (the functional group is changed) to bond with a solid electrolyte or the like. This interaction contributes to the adsorption of the fibrous binder with the solid particles during or during the preparation of the solid electrolyte composition. The functional groups also interact with the surface of the current collector.

Examples of the acidic functional group is not particularly limited, a carboxylic acid group (-COOH), a sulfonic acid group (sulfo group: _-SO 3 H) and phosphate groups (phospho group: -OPO _{(OH) 2,} etc.) is preferably mentioned Be done. The acidic functional group may be a salt thereof or an ester. Examples of the salt include sodium salt, calcium salt and the like. Examples of the ester include an alkyl ester and an aryl ester. In the case of an ester, the number of carbon atoms is preferably 1 to 24, more preferably 1 to 12, and particularly preferably 1 to 6.
The basic functional group is not particularly limited, but an amino group is preferably mentioned. The amino group is not particularly limited, and examples thereof include an amino group having 0 to 20 carbon atoms. Amino groups include alkylamino groups and arylamino groups. The number of carbon atoms of the amino group is preferably 0 to 12, more preferably 0 to 6, and even more preferably 0 to 2. Examples of the amino group include amino, N, N-dimethylamino, N, N-diethylamino, N-ethylamino, anilino and the like.
Those capable of forming a salt, such as a hydroxy group and an amino group, may be a salt.
The alkoxysilyl group is not particularly limited, and preferably includes an alkoxysilyl group having 1 to 20 carbon atoms, for example, monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl and the like.

The aryl group may be a monocyclic ring or a fused ring. The number of carbon atoms is preferably 6 to 26, more preferably 6 to 20. Specifically, benzene, naphthalene, anthrene, phenanthrene, pyrene, tetracene, tetraphen, chrysen, triphenylene, pentacene, pentaphen, perylene, benzo [a] pyrene, coronene, anthanthrene, colannelen, ovalene, graphene, cyclo. Examples include a ring group consisting of paraphenylene, polyparaphenylene or cyclophen.
The heteroaryl group is not particularly limited, and examples thereof include a 5- or 6-membered heteroaryl group having at least one selected from an oxygen atom, a sulfur atom, and a nitrogen atom as a ring-constituting atom. The heteroaryl group may be a monocyclic ring or a fused ring, and preferably has 2 to 20 carbon atoms. For example, a heteroaryl group of the substituent T described later can be mentioned.

The aliphatic hydrocarbon ring group in which three or more rings are fused is not particularly limited as long as the aliphatic hydrocarbon ring is fused in three or more rings. Examples of the aliphatic hydrocarbon ring to be condensed include a saturated aliphatic hydrocarbon ring and an unsaturated aliphatic hydrocarbon ring. The aliphatic hydrocarbon ring is preferably a 5-membered ring or a 6-membered ring. In the aliphatic hydrocarbon ring group in which 3 or more rings are fused, the number of rings to be condensed is not particularly limited, but 3 to 5 rings are preferable, and 3 or 4 rings are more preferable.
The ring group in which the saturated aliphatic hydrocarbon ring or the unsaturated aliphatic hydrocarbon ring has three or more rings is not particularly limited, and examples thereof include a ring group made of a compound having a steroid skeleton. Compounds having a steroid skeleton include, for example, cholesterol, ergosterol, testosterone, estradiol, aldosterone, hydrocortisone, stigmasterol, thymosterol, lanosterol, 7-dehydrodesmosterol, 7-dehydrocholesterol, cholaneric acid, cholic acid, and lithocholic acid. Examples thereof include acids, deoxycholic acid, sodium deoxycholic acid, lithium deoxycholic acid, hyodeoxycholic acid, chenodeoxycholic acid, ursodeoxycholic acid, dehydrocholic acid, hokecholic acid, hyocholic acid, and compounds containing a skeleton thereof. Of these, a ring group composed of a compound having a cholesterol skeleton is more preferable.

The functional group selected from the functional group group (a) is appropriately selected, but is acidic when the solid electrolyte composition contains an inorganic solid electrolyte or a positive electrode active material in terms of binding property to the active material. A functional group, a basic functional group, a hydroxy group, a cyano group or an alkoxysilyl group is preferable, and a carboxylic acid group is more preferable. On the other hand, when the solid electrolyte composition contains a negative electrode active material or a conductive auxiliary agent, an aryl group, a heteroaryl group or an aliphatic hydrocarbon ring group having 3 or more rings fused is preferable, and a fat having 3 or more rings condensed. Group hydrocarbon ring groups are more preferred.
As the functional group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and an aryl group are preferable, and a carboxylic acid group is more preferable, in that they show high binding property regardless of the active material.

The number of functional groups in one molecule of the binder-forming polymer may be one or more, and it is preferable that the binder-forming polymer has a plurality of functional groups. Further, the number of types of functional groups is not particularly limited as long as it has at least one functional group, and may be one type or two or more types. When having two or more kinds of functional groups, two or more kinds of functional groups selected from the functional group group (a) can be separately and appropriately combined. Further, two or more functional groups selected from the functional group group (a) may be appropriately combined to form one composite functional group. The composite functional group comprises, for example, an aryl group, a heteroaryl group or an aliphatic hydrocarbon ring group having three or more fused rings, and an acidic functional group, a basic functional group, a hydroxy group, a cyano group or an alkoxysilyl group. The group is mentioned.

The binder-forming polymer (each constituent) may have a substituent. Examples of the substituent include a group selected from the following substituent T. Substituents T are listed below, but are not limited thereto.
Alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, for example, methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl group. (Preferably an alkenyl group having 2 to 20 carbon atoms, for example, vinyl, allyl, oleyl, etc.), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, for example, ethynyl, butadynyl, phenylethynyl, etc.), a cycloalkyl group. (Preferably a cycloalkyl group having 3 to 20 carbon atoms, for example, cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably an aryl group having 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl). , 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms, preferably having at least one oxygen atom, sulfur atom and nitrogen atom. It is a 5- or 6-membered heterocyclic group. The heterocyclic group includes an aromatic heterocyclic group (heteroaryl group) and an aliphatic heterocyclic group, for example, a tetrahydropyran ring group, a tetrahydrofuran ring group, 2-pyridyl. , 4-Pyridyl, 2-imidazolyl, 2-benzoimidazolyl, 2-thiazolyl, 2-oxazolyl, etc.), alkoxy group (preferably alkoxy group having 1 to 20 carbon atoms, for example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.) , Aryloxy group (preferably aryloxy group having 6 to 26 carbon atoms, for example, phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy group (-O to the above heterocyclic group). -A group to which a group is bonded), an alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc.), an aryloxycarbonyl group (preferably having 6 to 26 carbon atoms). Aryloxycarbonyl groups such as phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc., amino groups (preferably amino groups 0-20 carbon atoms, alkylamino groups, arylaminos, etc.) It contains a group, for example, amino (-NH ₂ ), N, N-dimethylamino, N, N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl group (preferably carbon number of carbons). 0 to 20 sulfamoyl groups such as N, N-dimethylsulfamoyl, N-phenylsulfomoyl, etc., acyl groups (alkylcarbonyl group, alkenylcarbonyl group, alkynylcarbonyl group, arylcarbonyl group, heterocyclic carbonyl group) , Preferably acyl groups having 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotinoyyl, etc., acyloxy groups (alkylcarbonyloxy groups, etc.) It contains an alkenylcarbonyloxy group, an alkynylcarbonyloxy group, an arylcarbonyloxy group, and a heterocyclic carbonyloxy group, preferably an acyloxy group having 1 to 20 carbon atoms, for example, acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadeca. Noyloxy, acryloyloxy, methacryloyloxy, crotonoyloxy, benzoyloxy, naphthoyloxy, nicotinoyyloxy, etc.), allylloyloxy groups (preferably allylloyloxy groups having 7 to 23 carbon atoms, for example, benzoyloxy, etc.) , Carbamoyl group (preferably a carbamoyl group having 1 to 20 carbon atoms, for example, N, N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), an acylamino group (preferably an acylamino group having 1 to 20 carbon atoms, for example, acetylamino, Benzoylamino, etc.), alkylthio groups (preferably alkylthio groups having 1 to 20 carbon atoms, such as methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio groups (preferably arylthio groups having 6 to 26 carbon atoms, such as phenylthio, etc.) 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), heterocyclic thio group (group in which -S- group is bonded to the above heterocyclic group), alkylsulfonyl group (preferably having 1 to 20 carbon atoms). Alkylsulfonyl groups such as methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl groups (preferably arylsulfonyl groups having 6 to 22 carbon atoms, such as benzenesulfonyl), alkylsilyl groups (preferably alkyls having 1 to 20 carbon atoms). Cyril groups such as monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl, etc.), arylsilyl groups (preferably arylsilyl groups having 6 to 42 carbon atoms, such as triphenylsilyl), phosphoryl groups (preferably). Is properly phosphate group 0 to 20 carbon atoms, for ^{example, -OP (= O) (R} P) 2), a phosphonyl group (preferably a phosphonyl group having 0 to 20 carbon atoms, for example, -P (= O) ( R ^P) _2), a phosphinyl group (preferably a phosphinyl group having 0 to 20 carbon atoms, for example, ^-P (R _P) 2), a sulfo group (sulfonic acid group), a carboxy group, hydroxy group, sulfanyl group, a cyano group , Halogen atoms (eg, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). ^RP is a hydrogen atom or a substituent (preferably a group selected from the substituent T).
Further, each of the groups listed in these substituents T may be further substituted with the above-mentioned substituent T.

When a compound, a substituent, a linking group or the like contains an alkyl group, an alkylene group, an alkenyl group, an alkenylene group, an alkynyl group and / or an alkynylene group, etc., they may be cyclic or chain-like, and may be branched in a straight line. May be good.

The content of the fibrous binder in the solid electrolyte composition can form a layer having excellent film strength, contact state between solid particles and binding force, and maintains excellent battery performance even after repeated charging and discharging. In terms of being able to be a solid secondary battery, 0.01% by mass or more is preferable, 0.05% by mass or more is more preferable, and 0.1% by mass or more is further preferable in 100% by mass of the solid component. From the viewpoint of battery capacity, the upper limit is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.
In the solid electrolyte composition of the present invention, the mass ratio of the total mass (total mass) of the inorganic solid electrolyte and the active material to the mass of the binder [(mass of the inorganic solid electrolyte + mass of the active material) / (mass of the binder)] is , 1,000 to 1 is preferable. This ratio is more preferably 500 to 2, and even more preferably 100 to 5.

The solid electrolyte composition of the present invention may contain one type of fibrous binder alone or two or more types.

The fibrous binder is a binder-forming polymer that satisfies the above-mentioned properties (P1) and (P2), and can be produced by forming the fibrous binder that satisfies the above-mentioned properties (B1) to (B3). Such a production method is not particularly limited, and examples thereof include a method of synthesizing a binder-forming polymer and forming the binder into a predetermined fibrous form.

The binder-forming polymer may be sequentially polymerized or sequentially polymerized in the presence of a catalyst (including a polymerization initiator, a chain transfer agent, etc.), if necessary, by arbitrarily combining a raw material compound for deriving a predetermined constituent component according to the type of main chain. It can be synthesized by chain polymerization (additional polymerization). The method and conditions for sequential polymerization or chain polymerization (addition polymerization) are not particularly limited, and known methods and conditions can be appropriately selected. Properties of the binder-forming polymer (P1) Elastic modulus and (P2) Elastic modulus are the type of the binder-forming polymer, the type of the constituent (raw material compound), the bonding mode or the content, the molecular weight of the polymer or the glass, respectively. It can be adjusted by the transition temperature and the like.
As the raw material compound, a known compound is appropriately selected depending on the type of the binder-forming polymer. For example, the raw material compounds described in JP-A-2015-08480 that form a polymer having a urethane bond, a polymer having a urea bond, a polymer having an amide bond (polyamide resin), a polymer having an imide bond, and the like can be mentioned. ..

The method for forming the synthesized binder-forming polymer into a predetermined fibrous form is not particularly limited, and examples thereof include an electrospinning method (electrospinning method). The electrospinning method is a method that utilizes an electrofluid phenomenon that occurs when a high voltage is applied between a spinning nozzle and an electrode installed facing the spinning nozzle, and is suitably applied to the production of nanofibers and the like. More specifically, by applying a high voltage to the spinning nozzle and injecting the polymer or polymer solution (to which the high voltage is applied) toward the electrode (earth or negatively charged target) from the spinning nozzle. , A method of spinning a polymer into fibers. By such an electrospinning method, a polymer formed in a fibrous form on an electrode is produced alone or in a deposited state (nonwoven fabric form). The electrospinning method can be performed by appropriately selecting a known device and method (condition). In the electrospinning method, the average diameter D and average of the fibrous binder are obtained by appropriately setting the solid content concentration or injection amount of the polymer solution to be used, the applied voltage, the injection distance (distance from the injection nozzle to the electrode), and the like. The length L and the ratio L / D can be adjusted, and the binder-forming polymer can be formed into a predetermined fibrous form.
For example, in some examples of the present invention, the average diameter D and the average length L of the fibers can be increased by increasing the solid content concentration or the injection amount of the polymer solution or shortening the injection distance. When the applied voltage is increased, the average diameter D of the fibers can be increased, while the average length L can be decreased.

<Active material>
The solid electrolyte composition of the present invention may also contain an active material. This active material is a substance capable of inserting and releasing ions of metal elements belonging to Group 1 or Group 2 of the Periodic Table. Examples of such an active material include a positive electrode active material and a negative electrode active material.
In the present invention, the solid electrolyte composition containing the positive electrode active material (the composition for the electrode) may be referred to as the composition for the positive electrode, and the solid electrolyte composition containing the negative electrode active material may be referred to as the composition for the negative electrode.

(Positive electrode active material)
The positive electrode active material is preferably one capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above-mentioned characteristics, and may be a transition metal oxide, an organic substance, an element that can be composited with Li such as sulfur, or a composite of sulfur and a metal.
Among them, as the positive electrode active material, a transition metal oxide having preferably used a transition metal oxide, a transition metal element ^{M a (Co, Ni, Fe} , Mn, 1 or more elements selected from Cu and V) the The thing is more preferable. Further, the 1 (Ia) group elements of the transition metal oxide to elemental ^{M b} (Table metal periodic other than lithium, the elements of the 2 (IIa) group, Al, Ga, In, Ge , Sn, Pb, Elements such as Sb, Bi, Si, P or B) may be mixed. The mixing amount, 0~30mol% is preferred for the amount of the transition metal element ^{M a (100mol%).} That the molar ratio of li / ^{M a} is synthesized by mixing so that 0.3 to 2.2 is more preferable.
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 phosphoric acid compound, and (MD). ) Lithium-containing transition metal halide phosphoric acid compound, (ME) lithium-containing transition metal silicic acid compound and the like can be mentioned.

(MA) Specific examples of the transition metal oxide having a layered rock salt structure include LiCoO ₂ (lithium cobalt oxide [LCO]), LiNi ₂ O ₂ (lithium nickel oxide), LiNi _0.85 Co _0.10 Al _{0. 05} O ₂ (Nickel Lithium Cobalt Lithium Aluminate [NCA]), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (Nickel Manganese Lithium Cobalt Oxide [NMC]) and LiNi _0.5 Mn _0.5 O ₂ ( Lithium manganese nickel oxide).
(MB) 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 Nimn ₃ O ₈ may be mentioned.
Examples of the (MC) lithium-containing transition metal phosphate compound include olivine-type iron phosphate salts such as _{LiFePO 4} and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as _{LiFeP 2} O _{7 , LiCoPO 4, and the} like. Examples thereof include cobalt phosphates of Li ₃ V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate) and other monoclinic pyanicon-type vanadium phosphate salts.
(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 Examples thereof include cobalt fluoride phosphates such as.
Examples of the (ME) lithium-containing transition metal silicic acid 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 in the form of particles. The average particle size (sphere-equivalent 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 size of the positive electrode active material particles can be measured in the same manner as the average particle size of the inorganic solid electrolyte. A normal crusher or classifier is used to make the positive electrode active material a predetermined particle size. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling airflow type jet mill, a sieve, or the like is preferably used. At the time of pulverization, wet pulverization in which an organic solvent such as water or methanol coexists can also be performed, if necessary. It is preferable to perform classification in order to obtain a desired particle size. The classification method is not particularly limited, and a sieve, a wind power classifier, or the like can be used as needed. Both dry and wet classifications can be used.
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.

The positive electrode active material may be used alone or in combination of two or more.
When forming the positive electrode active material layer, the mass (mg) (grain amount) of the positive electrode active material 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.

The content of the positive electrode active material in the composition for the electrode is not particularly limited, and is preferably 10 to 95% by mass, more preferably 30 to 90% by mass, and further preferably 50 to 85% by mass in terms of solid content of 100% by mass. It is preferable, and 55 to 80% by mass is particularly preferable.

(Negative electrode active material)
The negative electrode active material is preferably one capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above-mentioned characteristics, and examples thereof include a carbonaceous material, a metal oxide, a metal composite oxide, a lithium simple substance, a lithium alloy, and a negative electrode active material capable of forming an alloy with lithium. .. Of these, carbonaceous materials, metal composite oxides or elemental lithium are preferably used from the viewpoint of reliability.
A negative electrode active material that can be alloyed with lithium is preferable in that the capacity of the all-solid-state secondary battery can be increased. Although the details will be described later, the solid electrolyte layer formed of the solid electrolyte composition of the present invention maintains a strong bonded state and a contact state between the solid particles even if the volume changes, and therefore, in the present invention, the negative electrode activity is maintained. As the material, an active material that can be alloyed with the above lithium, which has a large expansion and contraction due to charging and discharging and has room for improvement in terms of battery life, can be used. This makes it possible to increase the capacity of the all-solid-state secondary battery and extend the life of the battery.

The carbonaceous material used as the negative electrode active material is a material substantially composed of carbon. For example, various synthesis of 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 mentioned. Further, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, gas phase-grown carbon fiber, dehydrated PVA (polyvinyl alcohol) -based carbon fiber, lignin carbon fiber, glassy carbon fiber and activated carbon fiber. Kind, mesophase microspheres, graphite whiskers, flat plates and the like can also be mentioned.
These carbonaceous materials can also be divided into non-graphitizable carbonaceous materials (also referred to as hard carbon) and graphite-based carbonaceous materials depending on the degree of graphitization. Further, the carbonaceous material preferably has the plane spacing or density and the crystallite size described in JP-A-62-22066, JP-A-2-6856, and JP-A-3-45473. The carbonaceous material does not have 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, and the like should be used. You can also.
As the carbonaceous material, hard carbon or graphite is preferably used, and graphite is more preferably used.

The metal or semi-metal element oxide applied as the negative electrode active material is not particularly limited as long as it is an oxide capable of storing and releasing lithium, and is a composite of a metal element oxide (metal oxide) and a metal element. Examples thereof include oxides or composite oxides of metal elements and semi-metal elements (collectively referred to as metal composite oxides) and oxides of semi-metal elements (semi-metal oxides). As these oxides, amorphous oxides are preferable, and chalcogenides, which are reaction products of metal elements and elements of Group 16 of the Periodic Table, are also preferable. In the present invention, the metalloid element means an element exhibiting properties intermediate between a metalloid element and a non-metalloid element, and usually contains six elements of boron, silicon, germanium, arsenic, antimony and tellurium, and further selenium. , Polonium and Asstatin. Further, "amorphous" means an X-ray diffraction method using CuKα rays, which has a broad scattering zone having an apex in a region of 20 ° to 40 ° at a 2θ value, and a crystalline diffraction line is used. You may have. The strongest intensity of the crystalline diffraction lines seen at the 2θ value of 40 ° to 70 ° is 100 times or less the diffraction line intensity of the apex of the broad scattering zone seen at the 2θ value of 20 ° to 40 °. It is preferable that it is 5 times or less, and it is particularly preferable that it does not have a crystalline diffraction line.

Among the compound group consisting of the amorphous oxide and the chalcogenide, the amorphous oxide of the metalloid element or the chalcogenide is more preferable, and the elements of the Group 13 (IIIB) to 15 (VB) of the Periodic Table (for example). , Al, Ga, Si, Sn, Ge, Pb, Sb and Bi) alone or a (composite) oxide consisting of two or more combinations thereof, or chalcogenide is particularly preferable. 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 may preferably be mentioned.
Negative negative active materials that can be used in combination with amorphous oxides such as Sn, Si, and Ge include carbonaceous materials that can occlude and / or release lithium ions or lithium metals, lithium alone, lithium alloys, and lithium. A negative electrode active material that can be alloyed with is preferably mentioned.

It is preferable that the oxide of a metal or a metalloid element, particularly a metal (composite) oxide and the chalcogenide, contains at least one of titanium and lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics. Examples of the lithium-containing metal composite oxide (lithium composite metal oxide) include a composite oxide of lithium oxide and the metal (composite) oxide or the chalcogenide, and more specifically, Li ₂ SnO _2. Can be mentioned.
It is also preferable that the negative electrode active material, for example, a metal oxide, contains a titanium atom (titanium oxide). Specifically, Li ₄ Ti ₅ O ₁₂ (lithium titanate [LTO]) has excellent rapid charge / discharge characteristics because the volume fluctuation during occlusion and release of lithium ions is small, and deterioration of the electrodes is suppressed and lithium ion secondary. It is preferable in that the life of the battery can be improved.

The lithium alloy as the negative electrode active material is not particularly limited as long as it is an alloy usually used as the negative electrode active material of the 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 usually used as a negative electrode active material for a secondary battery. In such an active material, the expansion and contraction due to charging and discharging becomes large, so that the bound state and the contact state of the solid particles are impaired, but in the present invention, the strong bound state and the contact state can be maintained by the binder. Examples of such an active material include a (negative electrode) active material having a silicon element or a tin element (alloy, etc.), and metals such as Al and In, and a negative electrode active material having a silicon element that enables a higher battery capacity. (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 these negative electrode active materials (Si negative electrode containing a silicon element-containing active material, Sn negative electrode containing an active material having a tin element, etc.) is used as a carbon negative electrode (graphite, acetylene black, etc.). In comparison, more Li ions can be stored. That is, the occluded 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 drive time can be lengthened.
Examples of the silicon element-containing active material include silicon materials such as Si and SiOx (0 <x≤1), and silicon-containing alloys containing titanium, vanadium, chromium, manganese, nickel, copper, lanthanum, and the like (for example,). LaSi ₂ , VSi ₂ , La-Si, Gd-Si, Ni-Si) or organized active material (eg LaSi ₂ / Si), as well as silicon and tin elements such as _{SnSiO 3} , SnSiS _{3 and the like.} Examples include active materials containing the above. The SiOx itself can be used as a negative electrode active material (metalloid oxide), and since Si is generated by the operation of an all-solid-state secondary battery, the negative electrode active material that can be alloyed with lithium (its). It can be used as a precursor substance).
Examples of the negative electrode active material having a tin element include Sn, SnO, SnO ₂ , SnS, SnS ₂ , and the above-mentioned active material containing a silicon element and a tin element. Further, a composite oxide with lithium oxide, for example, Li ₂ SnO ₂ can also be mentioned.

In the present invention, the above-mentioned negative electrode active material can be used without particular limitation, but in terms of battery capacity, a negative electrode active material that can be alloyed with silicon is a preferred embodiment as the negative electrode active material. , The above silicon material or a silicon-containing alloy (an alloy containing a silicon element) is more preferable, and it is further preferable to contain silicon (Si) or a silicon-containing alloy.

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 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 obtain a predetermined particle size, a normal crusher or classifier is used as in the case of the positive electrode active material.

The chemical formula of the compound obtained by the above calcination can be calculated from the inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method and the mass difference of the powder before and after the calcination as a simple method.

The negative electrode active material may be used alone or in combination of two or more.
When the negative electrode active material layer is formed, the mass (mg) (grain amount) of the negative electrode active material 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.

The content of the negative electrode active material in the composition for the electrode is not particularly limited, and is preferably 10 to 80% by mass, more preferably 20 to 80% by mass, based on 100% by mass of the solid content.

In the present invention, when the negative electrode active material layer is formed by charging the secondary battery, instead of the negative electrode active material, a metal belonging to Group 1 or Group 2 of the periodic table generated in the all-solid secondary battery is used. Ions can be used. By combining these ions with electrons and precipitating them as a metal, a negative electrode active material layer can be formed.

(Coating of active material)
The surfaces of the positive electrode active material and the negative electrode active material may be surface-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 thereof include spinel titanate, tantalum oxide, niobate oxide, lithium niobate compound and the like, and specific examples thereof include 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 can be mentioned.
Further, the surface of the electrode containing the positive electrode active material or the negative electrode active material may be surface-treated with sulfur or phosphorus.
Further, the particle surface of the positive electrode active material or the negative electrode active material may be surface-treated with active light rays or an active gas (plasma or the like) before and after the surface coating.

<Conductive aid>
The solid electrolyte composition of the present invention may also contain a conductive auxiliary agent. The conductive auxiliary agent is not particularly limited, and those known as general conductive auxiliary agents can be used. For example, graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black and furnace black, atypical carbon such as needle coke, gas phase growth carbon fiber or carbon nanotubes, which are electron conductive materials. It may be a carbon fiber such as graphite, a carbonaceous material such as graphite or fullerene, a metal powder such as copper or nickel, or a metal fiber, and a conductive polymer such as polyaniline, polypyrrole, polythiophene, polyacetylene or a polyphenylene derivative. You may use it.
In the present invention, when the active material and the conductive auxiliary agent are used in combination, among the above conductive auxiliary agents, the ion of a metal belonging to the Group 1 or Group 2 of the periodic table when the battery is charged and discharged (preferably Li). A conductive auxiliary agent is one that does not insert and release ions) and does not function as an active material. Therefore, among the conductive auxiliary agents, 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 auxiliary agents. Whether or not the battery functions as an active material when it is charged and discharged is not unique and is determined by the combination with the active material.

As the conductive auxiliary agent, one kind may be used, or two or more kinds may be used.
The total content of the conductive auxiliary agent in the composition for the electrode is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass, based on 100% by mass of the solid content.

The shape of the conductive auxiliary agent is not particularly limited, but is preferably in the form of particles. The median diameter D50 of the conductive auxiliary agent is not particularly limited, and is preferably 0.01 to 1 μm, preferably 0.02 to 0.1 μm, for example.

<Dispersion medium>
The solid electrolyte composition of the present invention contains a dispersion medium. When this solid electrolyte composition contains a dispersion medium, in addition to the usual effects as a dispersion medium (improvement of composition uniformity, improvement of handleability, etc.), an effect of controlling the cohesiveness of the fibrous binder can be obtained.
The dispersion medium may be any one that disperses each component contained in the solid electrolyte composition of the present invention, and preferably one that disperses the above-mentioned fibrous binder (polymer constituting this binder) in the form of particles is selected. Will be done.

Examples of the dispersion medium used in the present invention include various organic solvents, and examples of the organic solvent include alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic compounds, aliphatic compounds, nitrile compounds, and esters. Examples thereof include each solvent such as a compound.

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, and 2 -Methyl-2,4-pentanediol, 1,3-butanediol, 1,4-butanediol can be mentioned.

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, monobutyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, etc.). 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 (tetratetra, dioxane (1,2-, (Including each isomer of 1,3- and 1,4-), etc.).

Examples of the amide compound include N, N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, formamide, N-methylformamide and acetamide. , N-Methylacetamide, N, N-dimethylacetamide, N-methylpropaneamide, 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 (MEK), methyl isobutyl ketone, cyclohexanone, and diisobutyl ketone (DIBK).
Examples of the aromatic compound include aromatic hydrocarbon compounds such as benzene, toluene and xylene.
Examples of the aliphatic compound include aliphatic hydrocarbon compounds such as hexane, heptane, octane, and decane.
Examples of the nitrile compound include acetonitrile, propionitrile, isobutyronitrile and the like.
Examples of the ester compound include ethyl acetate, butyl acetate, propyl acetate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, butyl pentanate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, isobutyl isobutyrate, and pivalic acid. Examples thereof include carboxylic acid esters such as propyl, isopropyl pivalate, butyl pivalate, and isobutyl pivalate.
Examples of the non-aqueous dispersion medium include the above aromatic compounds and aliphatic compounds.

In the present invention, the dispersion medium is preferably a ketone compound, an ester compound, an aromatic compound or an aliphatic compound, and more preferably contains at least one selected from a ketone compound, an ester compound, an aromatic compound and an aliphatic compound. ..
The dispersion medium contained in the solid electrolyte composition may be one kind or two or more kinds, and it is preferable that there are two or more kinds.

The total content of the dispersion medium in the solid electrolyte composition is not particularly limited, and is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and particularly preferably 40 to 60% by mass.

<Other additives>
The solid electrolyte composition of the present invention has, as desired, lithium salts, ionic liquids, thickeners, cross-linking agents (such as those that undergo a cross-linking reaction by radical polymerization, condensation polymerization or ring-opening polymerization) as components other than the above-mentioned components. ), Polymerization initiators (such as those that generate acids or radicals by heat or light), defoaming agents, leveling agents, dehydrating agents, antioxidants and the like.
The solid electrolyte composition of the present invention includes both an embodiment containing a binder other than the above-mentioned fibrous binder and an embodiment not containing the above-mentioned fibrous binder. The aspect of not containing a binder other than the fibrous binder means that the content of the binder other than the fibrous binder in the solid electrolyte composition is 1% by mass or less with respect to 100% by mass of the solid content. Examples of the binder other than the fibrous binder include those usually used for solid electrolyte compositions, for example, a particulate or fibrous binder formed of a resin or an inorganic material, and a dispersion medium formed of a resin or an inorganic material. Examples include binders that dissolve in.
In the embodiment containing a binder other than the fibrous binder, the content of the binder in the solid electrolyte composition is 0.02 to 0.02 to 100% by mass of the solid component in total of the fibrous binder and the binder other than the fibrous binder. It is preferably 30% by mass, more preferably 0.05 to 20% by mass. The content of the fibrous binder is as described above, but is preferably 20 to 100% by mass, preferably 30 to 100% by mass, based on the total content of the fibrous binder and the binder other than the fibrous binder. Is more preferable. The content of the binder other than the fibrous binder is not particularly limited, but is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, based on 100% by mass of the solid component.

[Manufacturing method of solid electrolyte composition]
The solid electrolyte composition of the present invention can be prepared as a slurry, preferably by mixing an inorganic solid electrolyte, a fibrous binder, a dispersion medium, and if necessary, other components with various commonly used mixers, for example. ..
The mixing method is not particularly limited, and they may be mixed all at once or sequentially. The fibrous binder is usually used as a dispersion liquid of the fibrous binder, but is not limited thereto. The mixing environment is not particularly limited, and examples thereof include under dry air or under an inert gas.
In the production of the solid electrolyte composition of the present invention, the fibrous binder can be used as it is obtained. That is, it may be used in a state where it is not entangled with other fibrous binders (a state in which the non-woven fabric is defibrated by a normal defibration method), or it may be used in the form of a fibrous film (nonwoven fabric). When used in the form of a fibrous film, it may be defibrated in the dispersion medium by a shearing force or the like in addition to the dispersion medium, and a composition containing a component other than the fibrous binder is impregnated into the fibrous binder. May be good.

[Solid electrolyte-containing sheet]
The solid electrolyte-containing sheet of the present invention is a sheet-like molded body capable of forming a constituent layer of an all-solid secondary battery, and includes various aspects depending on its use. For example, a sheet preferably used for a solid electrolyte layer (also referred to as a solid electrolyte sheet for an all-solid secondary battery), an electrode, or a sheet preferably used for a laminate of an electrode and a solid electrolyte layer (an electrode for an all-solid secondary battery). Sheet) and the like.

The solid electrolyte sheet for an all-solid secondary battery of the present invention may be a sheet having a solid electrolyte layer, and even a sheet having a solid electrolyte layer formed on a base material does not have a base material and is a solid electrolyte layer. It may be a sheet formed of. The solid electrolyte sheet for an all-solid secondary battery may have another layer in addition to the solid electrolyte layer. Examples of the other layer include a protective layer (release sheet), a current collector, a coat layer, and the like.
As the solid electrolyte sheet for an all-solid secondary battery of the present invention, for example, a sheet having a layer composed of the solid electrolyte composition of the present invention, a normal solid electrolyte layer, and a protective layer if necessary, in this order on a substrate. Can be mentioned. The solid electrolyte layer formed of the solid electrolyte composition of the present invention contains an inorganic solid electrolyte and a fibrous binder, and as described above, the contact state between the inorganic solid electrolytes and the binding force between the solid particles and the like. And are improved in a well-balanced manner. In the solid electrolyte layer, the inorganic solid electrolyte and the fibrous binder may be in a state where the inorganic solid electrolyte is bound by the fibrous binder. For example, the inorganic solid electrolyte and the fibrous binder may interact with each other or have a structure. It is a complex. The complex is not particularly limited, and examples thereof include the embodiments described in the above-mentioned solid electrolyte composition. The solid electrolyte layer is the same as the solid electrolyte layer in the all-solid-state secondary battery described later, and usually does not contain an active material. The solid electrolyte sheet for an all-solid-state secondary battery can be suitably used as a material constituting the solid electrolyte layer of the all-solid-state secondary battery.

The base material is not particularly limited as long as it can support the solid electrolyte layer, and examples thereof include a material described in the current collector described later, a sheet body (plate-shaped body) such as an organic material and an inorganic material. Examples of the organic material include various polymers, and specific examples thereof include polyethylene terephthalate, polypropylene, polyethylene, and cellulose. Examples of the inorganic material include glass, ceramic and the like.

The electrode sheet for an all-solid-state secondary battery of the present invention (also simply referred to as “the electrode sheet of the present invention”) may be an electrode sheet having an active material layer, and the active material layer is on a base material (collector). It may be a sheet formed in the above, or a sheet having no base material and formed from an active material layer. This electrode sheet is usually a sheet having a current collector and an active material layer, but has an embodiment having a current collector, an active material layer and a solid electrolyte layer in this order, and a current collector, an active material layer and a solid electrolyte. An embodiment having a layer and an active material layer in this order is also included. The electrode sheet of the present invention may have the other layers described above. Each layer constituting the electrode sheet of the present invention is the same as each layer described in the all-solid-state secondary battery described later.
The electrode sheet of the present invention is a negative electrode active material in that when used as a negative electrode active material layer of an all-solid secondary battery, the discharge capacity (discharge capacity density) is further increased while maintaining low resistance and long battery life. A negative electrode sheet for an all-solid secondary battery containing an active material that can be alloyed with lithium is a preferred embodiment.
The active material layer of the electrode sheet is preferably formed of the solid electrolyte composition (composition for an electrode) of the present invention containing an active material, and in particular, the negative electrode sheet contains a negative electrode active material that can be alloyed with lithium. It is preferably formed of the solid electrolyte composition of the present invention. Similar to the solid electrolyte layer formed of the solid electrolyte composition of the present invention, the active material layer of the electrode sheet is a composite of solid particles containing an active material and a conductive auxiliary agent and a fibrous binder, and is a solid particle. The contact state between the solid particles and the binding force between the solid particles are improved in a well-balanced manner. This electrode sheet can be suitably used as a material constituting the (negative electrode or positive electrode) active material layer of the all-solid-state secondary battery.

[Manufacturing method of solid electrolyte-containing sheet]
The method for producing the solid electrolyte-containing sheet is not particularly limited. The solid electrolyte-containing sheet can be produced using the solid electrolyte composition of the present invention. For example, the solid electrolyte composition of the present invention is prepared as described above, and the obtained solid electrolyte composition is formed into a film (coating and drying) on a substrate (may be via another layer). , A method of forming a solid electrolyte layer (coating dry layer) on a substrate can be mentioned. Thereby, if necessary, a solid electrolyte-containing sheet having a base material (current collector) and a coating dry layer can be produced. Here, the coating dry layer is a layer formed by applying the solid electrolyte composition of the present invention and drying the dispersion medium (that is, the solid electrolyte composition of the present invention is used, and the solid of the present invention is used. A layer having a composition obtained by removing a dispersion medium from an electrolyte composition). This coated dry layer contains the above-mentioned complex of an inorganic solid electrolyte and a fibrous binder. In the active material layer and the coating dry layer, the dispersion medium may remain as long as the effect of the present invention is not impaired, and the residual amount may be, for example, 3% by mass or less in each layer.
In the above production method, the solid electrolyte composition of the present invention is preferably used as a slurry, and if desired, the solid electrolyte composition of the present invention can be made into a slurry by a known method. Each step of the solid electrolyte composition of the present invention, such as application and drying, will be described in the following method for manufacturing an all-solid-state secondary battery.

In the method for producing a solid electrolyte-containing sheet of the present invention, the coating dry layer obtained as described above can also be pressurized. The pressurizing conditions and the like will be described later in the method for manufacturing an all-solid-state secondary battery.
Further, in the method for producing a solid electrolyte-containing sheet of the present invention, the base material, the protective layer (particularly the release sheet) and the like can be peeled off.

[All-solid-state secondary battery]
The all-solid secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer facing the positive electrode active material layer, and a solid electrolyte layer arranged between the positive electrode active material layer and the negative electrode active material layer. Have. The positive electrode active material layer is formed on the positive electrode current collector, if necessary, and constitutes the positive electrode. The negative electrode active material layer is formed on the negative electrode current collector, if necessary, and constitutes the negative electrode.
At least one layer of the solid electrolyte layer, the positive electrode active material layer and the negative electrode active material layer of the all-solid secondary battery is preferably formed of the solid electrolyte composition of the present invention, and the negative electrode active material layer is alloyed with lithium. It is more preferably formed of the solid electrolyte composition of the present invention containing a convertible active material, and comprises an embodiment in which all layers are formed of the solid electrolyte composition of the present invention. The all-solid-state secondary battery of the present invention exhibits a large discharge capacity (discharge capacity density) with low resistance, and can maintain a large discharge capacity (achieve a long battery life) even after repeated charging and discharging. The all-solid secondary battery formed of the solid electrolyte composition of the present invention in which the negative electrode active material layer contains an active material that can be alloyed with lithium has a higher discharge capacity (a larger discharge capacity while achieving low resistance and long battery life. Discharge capacity density) is shown.
The positive electrode active material layer and the negative electrode active material layer contain an inorganic solid electrolyte, an active material, an appropriate binder, a conductive auxiliary agent, and each of the above components. When the negative electrode active material layer is not formed of the solid electrolyte composition of the present invention, the negative electrode active material layer is a layer containing the inorganic solid electrolyte, the active material and each of the above components as appropriate, and a layer made of the metal or alloy described as the negative electrode active material (lithium metal). Layers and the like), and further, layers (sheets) made of the carbonaceous material described above as the negative electrode active material are adopted. The layer made of a metal or an alloy includes, for example, a layer formed by depositing or molding a powder of a metal or an alloy such as lithium, a metal foil or an alloy foil, a vapor-deposited film, and the like. The thickness of the layer made of a metal or an alloy and the layer made of a carbonaceous material are not particularly limited, and can be, for example, 0.01 to 100 μm. The solid electrolyte layer contains a solid electrolyte having ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, an appropriate binder, and each of the above components.

(Positive electrode active material layer, solid electrolyte layer, negative electrode active material layer)
In the all-solid-state secondary battery of the present invention, as described above, the solid electrolyte composition or the active material layer can be formed of the solid electrolyte composition of the present invention or the solid electrolyte-containing sheet. The solid electrolyte layer and the active material layer to be formed are preferably the same as those in the solid content of the solid electrolyte composition with respect to each component contained and the content thereof, unless otherwise specified.
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 5 to 1,000 μm, more preferably 10 μm or more and less than 500 μm, respectively, considering 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 the thickness of at least one of the positive electrode active material layer, the solid electrolyte layer and the negative electrode active material layer is 20 μm or more and less than 500 μm.

The positive electrode active material layer and the negative electrode active material layer may each have a current collector on the opposite side of the solid electrolyte layer.

(Case)
Depending on the application, the all-solid-state secondary battery of the present invention may be used as an all-solid-state secondary battery with the above structure, but in order to form a dry battery, it should be further enclosed in a suitable housing. Is preferable. The housing may be made of metal or resin (plastic). When metallic materials are used, for example, those made of aluminum alloy and stainless steel can be mentioned. It is preferable that the metallic housing is divided into a positive electrode side housing and a negative electrode side housing, 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 a short circuit.

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

FIG. 1 is a schematic sectional view showing an all-solid-state secondary battery (lithium ion secondary battery) according to a preferred embodiment of the present invention. The all-solid secondary battery 10 of the present embodiment has 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 when viewed from the negative electrode side. .. Each layer is in contact with each other and has a laminated structure. By adopting such a structure, during charging, electrons (e ⁻ ) are supplied to the negative electrode side, and lithium ions (Li ⁺ ) are accumulated there. On the other hand, at the time of discharge, the lithium ion (Li ⁺ ) accumulated in the negative electrode is returned to the positive electrode side, and electrons are supplied to the operating portion 6. In the illustrated example, a light bulb is used for the operating portion 6, and the light bulb is turned on by electric discharge.
The solid electrolyte composition of the present invention can be preferably used as a material for forming a solid electrolyte layer, a negative electrode active material layer or a positive electrode active material layer. Further, the solid electrolyte-containing sheet of the present invention is suitable as a solid electrolyte layer, a negative electrode active material layer or a positive electrode active material layer.
In the present invention, the positive electrode active material layer (hereinafter, also referred to as a positive electrode layer) and the negative electrode active material layer (hereinafter, also referred to as a negative electrode layer) may be collectively referred to as an electrode layer or an active material layer.

When an all-solid secondary battery having the layer structure shown in FIG. 1 is placed in a 2032 type coin case, the all-solid secondary battery is referred to as an all-solid secondary battery laminate, and the all-solid secondary battery laminate is referred to as an all-solid secondary battery laminate. Batteries manufactured in a 2032 type coin case are sometimes referred to as all-solid-state secondary batteries.

(Positive electrode active material layer, solid electrolyte layer, negative electrode active material layer)
In the all-solid-state secondary battery 10, any one of the solid electrolyte layer and the active material layer is formed by using the solid electrolyte composition of the present invention or the solid electrolyte-containing sheet. In a preferred embodiment, all layers are formed using the solid electrolyte composition of the present invention or the solid electrolyte-containing sheet, and in another preferred embodiment, the negative electrode active material layer contains an active material that can be alloyed with lithium. It is formed of the solid electrolyte composition of No. 1 or the negative electrode sheet for an all-solid secondary battery.
When at least one of the solid electrolyte layer and the positive electrode active material layer is formed by using the solid electrolyte composition of the present invention or the solid electrolyte-containing sheet, the negative electrode active material layer is a layer made of a metal or an alloy as the negative electrode active material. It can also be formed by using a layer made of a carbonaceous material as a negative electrode active material, and further by precipitating a metal belonging to Group 1 or Group 2 of the Periodic Table on a negative electrode current collector or the like during charging. ..
The components contained in the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 may be of the same type or different from each other.

The positive electrode current collector 5 and the negative electrode current collector 1 are preferably electron conductors.
In the present invention, either or both of the positive electrode current collector and the negative electrode current collector may be collectively referred to as a current collector.
As a material for forming a positive electrode current collector, in addition to aluminum, aluminum alloy, stainless steel, nickel and titanium, the surface of aluminum or stainless steel is treated with carbon, nickel, titanium or silver (a thin film is formed). Of these, aluminum and aluminum alloys are more preferable.
As a material for forming the negative electrode current collector, in addition to aluminum, copper, copper alloy, stainless steel, nickel and titanium, carbon, nickel, titanium or silver is treated on the surface of aluminum, copper, copper alloy or stainless steel. Preferably, aluminum, copper, copper alloy and stainless steel are more preferable.

The shape of the current collector is usually a film sheet, but a net, a punched body, a lath body, a porous body, a foam body, a molded body of a fiber group, or the like can also be used.
The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm. Further, it is also preferable that the surface of the current collector is made uneven by surface treatment.

In the present invention, a functional layer, a member, or the like is appropriately interposed or arranged between or outside each 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. You may. Further, each layer may be composed of a single layer or a plurality of layers.

[Manufacturing method of all-solid-state secondary battery]
The all-solid-state secondary battery of the present invention is not particularly limited, and can be produced (including) through the method for producing the solid electrolyte composition of the present invention. Focusing on the raw materials used, it can also be produced using the solid electrolyte composition of the present invention. Specifically, for the all-solid-state secondary battery, the solid electrolyte composition of the present invention is prepared as described above, and the obtained solid electrolyte composition or the like is used to prepare the solid electrolyte layer of the all-solid-state secondary battery and the solid electrolyte layer. / Or can be produced by forming an active material layer. This makes it possible to manufacture an all-solid-state secondary battery that maintains a high battery capacity even after repeated charging and discharging. Since the method for preparing the solid electrolyte composition of the present invention is as described above, it will be omitted.

The all-solid-state secondary battery of the present invention includes a step of applying the solid electrolyte composition of the present invention on a base material (for example, a metal foil serving as a current collector) to form a coating film (form a film). It can be manufactured via a (via) method.
For example, the solid electrolyte composition (composition for electrodes) of the present invention is applied as a composition for a positive electrode on a metal foil which is a positive electrode current collector to form a positive electrode active material layer, and a positive electrode for an all-solid secondary battery is formed. Make a sheet. Next, the solid electrolyte composition of the present invention for forming the solid electrolyte layer is applied onto the positive electrode active material layer to form the solid electrolyte layer. Further, the solid electrolyte composition (composition for an electrode) of the present invention is applied as a composition for a negative electrode on the solid electrolyte layer to form a negative electrode active material layer. By superimposing a negative electrode current collector (metal leaf) on the negative electrode active material layer, an all-solid secondary battery having a structure in which a solid electrolyte layer is sandwiched between the positive electrode active material layer and the negative electrode active material layer can be obtained. Can be done. If necessary, this can be enclosed in a housing to obtain a desired all-solid-state secondary battery.
Further, by reversing the forming method of 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 superposed to manufacture an all-solid-state secondary battery. You can also do it.

Another method is as follows. That is, as described above, a positive electrode sheet for an all-solid-state secondary battery is manufactured. Further, the solid electrolyte composition of the present invention is applied as a composition for a negative electrode on a metal foil which is a negative electrode current collector to form a negative electrode active material layer, and a negative electrode sheet for an all-solid secondary battery is produced. Next, the solid electrolyte layer forming composition of the present invention is applied onto the active material layer of any one of these sheets as described above to form a solid electrolyte layer. Further, the other of the positive electrode sheet for the all-solid-state secondary battery and the negative electrode sheet for the all-solid-state secondary battery is laminated on the solid electrolyte layer so that the solid electrolyte layer and the active material layer are in contact with each other. In this way, an all-solid-state secondary battery can be manufactured.
As another method, the following method can be mentioned. That is, as described above, a positive electrode sheet for an all-solid-state secondary battery and a negative electrode sheet for an all-solid-state secondary battery are manufactured. Separately from this, the solid electrolyte composition is applied onto the substrate to prepare a solid electrolyte sheet for an all-solid secondary battery composed of a solid electrolyte layer. Further, the positive electrode sheet for the all-solid-state secondary battery and the negative electrode sheet for the all-solid-state secondary battery are laminated so as to sandwich the solid electrolyte layer peeled off from the base material. In this way, an all-solid-state secondary battery can be manufactured.

Each of the above manufacturing methods is a method for forming a solid electrolyte layer, a negative electrode active material layer and a positive electrode active material layer with the solid electrolyte composition of the present invention, but in the method for manufacturing an all-solid secondary battery of the present invention. Formes at least one of a solid electrolyte layer, a negative electrode active material layer, and a positive electrode active material layer with the solid electrolyte composition of the present invention. When the solid electrolyte layer is formed of a composition other than the solid electrolyte composition of the present invention, examples of the material thereof include commonly used solid electrolyte compositions. When the negative electrode active material layer is formed of a material other than the solid electrolyte composition of the present invention, a known negative electrode active material composition, a metal or alloy (metal layer) as the negative electrode active material, or a carbonaceous material as the negative electrode active material ( Carbon material layer) and the like. In addition, it belongs to the first or second group of the periodic table, which is accumulated in the negative electrode current collector by the initialization or charging during use, which will be described later, without forming the negative electrode active material layer at the time of manufacturing the all-solid secondary battery. A negative electrode active material layer can also be formed by binding metal ions with electrons and precipitating them as a metal on a negative electrode current collector or the like.
The solid electrolyte layer or the like can also be formed, for example, on a substrate or an active material layer by pressure molding a solid electrolyte composition or the like under pressure conditions described later.

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

When the solid electrolyte composition of the present invention is applied and dried as described above, the above-mentioned composite with the inorganic solid electrolyte, the fibrous binder, and the active material or the conductive auxiliary agent can be formed, and the solid particles and the like are strongly bonded to each other. It is possible to form a coating dry layer having a small interfacial resistance between solid particles.

It is preferable to pressurize the applied composition or each layer or the all-solid-state secondary battery after producing the all-solid-state secondary battery. It is also preferable to pressurize the layers in a laminated state. Examples of the pressurizing method include a hydraulic cylinder press machine and the like. The pressing force is not particularly limited, and is generally preferably in the range of 10 MPa or more, for example, 50 to 1500 MPa.
Further, the applied composition may be heated at the same time as pressurization. The heating temperature is not particularly limited and is generally in the range of 30 to 300 ° C. It can also be pressed at a temperature higher than the glass transition temperature of the inorganic solid electrolyte.
The 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 coating solvent or the dispersion medium remains.
In addition, each composition may be applied at the same time, and the application drying press may be performed simultaneously and / or sequentially. It may be laminated by transfer after being applied to different substrates.

The atmosphere during pressurization is not particularly limited, and may be any of air, dry air (dew point −20 ° C. or lower), inert gas (for example, argon gas, helium gas, nitrogen gas) and the like. Since the inorganic solid electrolyte reacts with moisture, the atmosphere during pressurization is preferably under dry air or in an inert gas.
The pressing time may be short (for example, within several hours) and high pressure may be applied, or medium pressure may be applied for a long time (1 day or more). In the case of an all-solid-state secondary battery other than the solid-state electrolyte-containing sheet, for example, a restraining tool (screw tightening pressure, etc.) for the all-solid-state secondary battery can be used in order to continue applying a medium pressure.
The press pressure may be uniform or different with respect to the pressed portion such as the sheet surface.
The press pressure can be changed according to the area and film thickness of the pressed portion. It is also possible to change the same part step by step with different pressures.
The pressed surface may be smooth or roughened.

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

[Use of all-solid-state secondary battery]
The all-solid-state secondary battery of the present invention can be applied to various uses. The application mode is not particularly limited, but for example, when it is mounted on an electronic device, it is a notebook computer, a pen input computer, a mobile computer, an electronic book player, a mobile phone, a cordless phone handset, a pager, a handy terminal, a mobile fax, or a mobile phone. Examples include copying, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, mini discs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, memory cards, etc. Other consumer products include automobiles (electric vehicles, etc.), electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.). .. Furthermore, it can be used for various military demands and space. It can also be combined with a solar cell.

Hereinafter, the present invention will be described in more detail based on examples. It should be noted that the present invention is not limited thereto. In the following examples, "parts" and "%" representing the composition are based on mass unless otherwise specified.

The fibrous binder and the inorganic solid electrolyte used in Examples and Comparative Examples were synthesized as follows.

<Synthesis Example 1: Synthesis of binder-forming polymer B-1 (preparation of polymer solution B-1)>
2.5 g of 2,2-bis (hydroxymethyl) butyric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 22.5 g of polycarbonate diol (trade name: Duranol T5650J, manufactured by Asahi Kasei Co., Ltd.) and 4,4'in a 500 mL three-necked flask. -Add 15.0 g of dicyclohexylmethane diisocyanate (manufactured by Wako Pure Chemical Industries, Ltd.) and 10.0 g of polybutadiene GI-1000 modified with hydroxyl groups at both ends (trade name: NISSO PB GI-1000, manufactured by Nippon Soda Co., Ltd.). , N-Methylpyrrolidone (NMP) in 117 g. To this solution, 100 mg of Neostan U-600 (trade name, manufactured by Nitto Kasei Co., Ltd.) was added and stirred at 80 ° C. for 4 hours. 1 g of methanol was added to this solution, and stirring was continued at 80 ° C. for 30 minutes to synthesize a binder-forming polymer B-1 to obtain a polymer solution B-1.

<Synthesis Examples 2-4: Synthesis of Binder Forming Polymers B-2 to B-4 (Preparation of Polymer Solutions B-2 to B-4)>
In the synthesis of the above-mentioned polymer B-1, the above-mentioned polymer B- except that the compound for guiding the constituents shown in Table 1 below was used as the compound for guiding each constituent in the amount used which is the content shown in the same table. Polymers B-2 to B-4 (polymer solutions B-2 to B-4) were synthesized (prepared) in the same manner as in the synthesis of 1.
All of the polymers B-1 to B-4 are polyurethane polymers having a carboxy group in the side chain among the functional groups contained in the functional group group (a).

<Synthesis Example 5: Synthesis of Binder Forming Polymer B-5 (Preparation of Polymer Solution B-5)>
3.3 g of diphenyl-3,3', 4,4'-tetracarboxylic dianhydride (DPTCA, manufactured by Tokyo Kasei Co., Ltd.) was placed in a 200 mL three-necked flask and dissolved in 50 mL of NMP. To this was added a 50 mL solution of NMP in which 6.7 g of polyetheramine (trade name: Jeffermin ED-600, manufactured by Huntsman) was dissolved in NMP (the NMP solution was added by dropping). This was heated and stirred at 40 ° C. for 2 hours to synthesize a polyamic acid.
Next, 2 g of acetic anhydride and 0.2 g of pyridine were added, and the mixture was further heated and stirred at 65 ° C. for 6 hours to carry out an imidization reaction to obtain a polymer solution B-5.
Polymer B-5 is a polyimide polymer having an aryl group (phenyl group) of a functional group contained in the functional group group (a) in its main chain.

<Preparation of binder-forming polymer B-6 (preparation of polymer solution B-6)>
As the polymer B-6, hydrogenated styrene-butadiene rubber (DYNARON1321P (trade name), manufactured by JSR Corporation) was dissolved in toluene to prepare a polymer solution B-6.
Polymer B-6 is a hydrocarbon-based polymer having an aryl group (phenyl group) of the functional group contained in the functional group group (a) in the side chain.

<Synthesis Example 6: Synthesis of Binder Forming Polymer CB-1 (Preparation of Polymer Solution CB-1)>
In the synthesis of the above-mentioned polymer B-5, the above-mentioned polymer B- except that the compound for guiding the constituents shown in Table 1 below was used as the compound for guiding each constituent in the amount used which is the content shown in the same table. Polymer CB-1 (polymer solution CB-1) was synthesized (prepared) in the same manner as in the synthesis of 5.
Polymer CB-1 is a polyimide polymer having an aryl group (phenyl group) of a functional group contained in the functional group group (a) in its main chain.

<Preparation of polymer CB-2 (preparation of polymer solution CB-2)>
As the polymer CB-2, the hydrogenated styrene-butadiene rubber (DYNARON1321P (trade name)) was dissolved in toluene to prepare a polymer solution CB-2.

<Measurement of polymer mass average molecular weight, elastic modulus, elastic deformation rate and glass transition temperature>
The mass average molecular weight (Mw) of each polymer synthesized or prepared was measured by the method described above. The results are shown in Table 1. The elastic modulus, elastic deformation rate and glass transition temperature (Tg) of each polymer were measured by the above-mentioned methods, and the results are shown in Table 2. The elastic modulus, elastic deformation rate, and Tg measured for each solid electrolyte composition and the binder-forming polymer taken out from the electrode sheet for an all-solid-state secondary battery described later by the above method are almost the same as the values shown in Table 2. I am doing it.

<Table abbreviation>
HMDI: 4,4'-dicyclohexylmethane diisocyanate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
MDI: Diphenylmethane diisocyanate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
DPTCA: Diphenyl-3,3', 4,4'-tetracarboxylic dianhydride (manufactured by Tokyo Kasei Co., Ltd.)
DMBA: 2,2-bis (hydroxymethyl) butyric acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
ED-600: Polyetheramine (Jeffamine ED-600 (trade name), manufactured by Huntsman, Mw600)
T5650J: Polycarbonate diol (Duranol T5650J (trade name), manufactured by Asahi Kasei Corporation, Mw2,000)
G3450J: Polycarbonate diol (Duranol G3450J (trade name), manufactured by Asahi Kasei Corporation, Mw800)
PPG400: Polypropylene glycol (Aldrich, Mw400)
EDA: Ethylenediamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
GI-1000: Hydroxyl-terminated polybutadiene with double-ended hydroxyl groups (NISSO PB GI-1000 (trade name), manufactured by Nippon Soda, Mw 1,500)
EPOL: Hydroxyl-terminated polyisoprene at both ends (Epol (trade name), manufactured by Idemitsu Kosan Co., Ltd., Mw2,500)
HSBR: Hydrogenated styrene-butadiene rubber (DYNARON1321P (trade name), manufactured by JSR Corporation)
ST: Styrene BD: (hydrogenated) butadiene Of the above components, the components containing an aliphatic hydrocarbon group having 5 or more carbon atoms are raw materials of HMDI, DMBA, T5650J, GI-1000, EPOL and ST. It is a component derived from a compound.
The components represented by any of the above formulas (1-1) to (1-6) are DPTCA, DMBA, PPG400, ED-600, EDA, T5650J, G3450J, GI-1000, EPOL, BD. It is a constituent component derived from each raw material compound of.
The constituent component represented by the above formula (2) is a constituent component derived from each of the raw material compounds of HMDI and MDI.

<Preparation of fibrous binders F-1 to F-15, CF-1, CF-3 and CF-4 (shape control)>
Using each polymer solution prepared above, fibrous binders F-1 to F-15, CF-1, CF-3 and CF-4 were prepared by electrospinning with each polymer in fiber shape. Specifically, in the electrospinning method, using the polymer solution shown in Table 1, the solid content concentration (0.5 to 30% by mass) of this polymer solution, the applied voltage (2 to 50 kV), and the spinning section (spinning). The injection distance (10 to 300 mm) from the nozzle) to the electrode was controlled (within the range described in parentheses above) to obtain each fibrous binder.

<Preparation of fibrous binder CF-2>
A dispersion of the particulate binder CF-2 was prepared using the polymer solution B-1. Specifically, while stirring the polymer solution B-1, toluene was added as a poor solvent and precipitated to obtain a dispersion liquid of the particulate binder CF-2. The average particle size of the particulate binder CF-2 in the dispersion was 1,000 nm. As the measuring method, the method described in International Publication No. 2017/131093A1 can be applied.

<Preparation of fibrous binder CF-5>
As the fibrous binder CF-5, the polymer solution CB-2 was used as it was without making the binder-forming polymer CB-2 fibrous.

<Measurement and calculation of average diameter D, average length L, and ratio L / D of fibrous binder>
The average diameter D and the average length L of each fibrous binder were measured by the above method, and the ratio L / D was calculated from the obtained results. The results are shown in Table 2.
The average diameter D, average length L, and ratio L / D measured or calculated for each solid electrolyte composition and the fibrous binder taken out from the electrode sheet for an all-solid secondary battery described later by the above method are , The values shown in Table 2 are almost the same.

<Synthesis Example 7: Synthesis of sulfide-based inorganic solid electrolyte Li-PS-based glass>
As a sulfide-based inorganic solid electrolyte, T.I. Ohtomo, A. Hayashi, M. et al. Tatsumisago, Y. et al. Tsuchida, S.A. Hama, K.K. Kawamoto, Journal of Power Sources, 233, (2013), pp231-235 and A.M. Hayashi, S.A. Hama, H. Morimoto, M.D. Tatsumi sago, T. et al. Minami, Chem. Let. , (2001), pp872-873, Li-PS-based glass was synthesized with reference to the non-patent literature.

Specifically, in a glove box under an argon atmosphere (dew point -70 ° C.), lithium sulfide _(Li 2 S, Aldrich Corp., purity> 99.98%) 2.42 g, diphosphorus pentasulfide _(P 2 S _5. Aldrich, purity> 99%) 3.90 g was weighed, placed in an agate mortar, and mixed for 5 minutes using an agate mortar. The mixing ratio of Li ₂ S and P ₂ S _{5 was Li 2} S: P ₂ S ₅ = 75: 25 in terms of molar ratio.
66 zirconia beads having a diameter of 5 mm were put into a 45 mL container made of zirconia (manufactured by Fritsch), the whole amount of the mixture of lithium sulfide and diphosphorus pentasulfide was put into the container, and the container was sealed under an argon atmosphere. This container was set on a planetary ball mill P-7 (trade name) manufactured by Frichchu, and mechanical milling was performed at a temperature of 25 ° C. and a rotation speed of 510 rpm for 20 hours. S-based glass, LPS) 6.20 g was obtained. The ionic conductivity was 0.28 mS / cm. The average particle size of the Li-P-S-based glass by the above measuring method was 15 μm.

Example 1
Using the obtained binder-forming polymer, a solid electrolyte composition, an all-solid-state secondary battery electrode sheet, and an all-solid-state secondary battery are manufactured, respectively, for an all-solid-state secondary battery electrode sheet and an all-solid-state secondary battery. The following characteristics were evaluated. The results are shown in Table 5.

<Preparation of solid electrolyte composition>
180 zirconia beads having a diameter of 5 mm were put into a zirconia 45 mL container (manufactured by Fritsch), 4.85 g of Li-PS-based glass synthesized in the above synthesis example 7, and a fibrous binder (particulate) shown in Table 3. In the case of the binder CF-2, 0.15 g (converted to solid content mass) and 8.0 g of heptane as a dispersion medium were added. After that, this container was set in a planetary ball mill P-7 (trade name) manufactured by Fritsch, and mixing was continued for 60 minutes at a temperature of 25 ° C. and a rotation speed of 250 rpm to prepare the solid electrolyte compositions S-1 to S-3, respectively. Prepared.
The solid electrolyte composition S-3 is a solid electrolyte composition for comparison.

<Manufacturing of electrode sheet for all-solid-state secondary battery (negative electrode sheet for all-solid-state secondary battery)>
(Preparation of composition a-1 for negative electrode)
180 zirconia beads having a diameter of 5 mm were placed in a 45 mL container made of zirconia (manufactured by Fritsch), 4.6 g of Li-PS-based glass synthesized in Synthesis Example 7 and 12.3 g of heptane as a dispersion medium (made by Fritsch). Total amount) was put in. This container was set on a planetary ball mill P-7 (trade name) manufactured by Fritsch, and stirred at 25 ° C. at a rotation speed of 200 pm for 30 minutes. After that, 4.6 g of Si (manufactured by Aldrich) as a negative electrode active material, 0.5 g of acetylene black (AB) as a conductive auxiliary agent, and 0.3 g of a fibrous binder F-1 were put into this container, and a planetary ball mill was added. A container was set in P-7, and mixing was continued for 30 minutes at a temperature of 25 ° C. and a rotation speed of 200 rpm to prepare a negative electrode composition a-1.
(Preparation of Compositions a-2 to a-24 for Negative Electrodes)
In the preparation of the negative electrode composition a-1, the negative electrode composition a-, except that the types and amounts of the inorganic solid electrolyte, the negative electrode active material, the fibrous binder and the conductive auxiliary agent were changed as shown in Table 4. The negative electrode compositions a-2 to a-24 were prepared in the same manner as in the preparation of 1.
In the preparation of the negative electrode compositions a-22 and a-23, 2.3 g each of graphite and Si was used as the negative electrode active material.
The negative electrode compositions a-17 to a-21 and a-24 are negative electrode compositions for comparison.

(Manufacture of negative electrode sheets A-1 to A-24 for all-solid-state secondary batteries)
The negative electrode composition prepared above was applied to a stainless steel (SUS) foil having a thickness of 15 μm as a negative electrode current collector, and a baker-type applicator (trade name: SA-201, manufactured by Tester Sangyo Co., Ltd.) was used to form the amount shown in Table 4. The negative electrode composition was dried by applying the mixture, heating at 80 ° C. for 1 hour, and further heating at 110 ° C. for 1 hour. Then, using a heat press machine, the dried composition for the negative electrode (coating and drying layer) is pressurized (20 MPa, 1 minute) while heating at 120 ° C. to form a laminated structure of the negative electrode active material layer and the SUS foil. Negative electrode sheets A-1 to A-24 for all-solid-state secondary batteries were prepared.
The negative electrode sheets A-17 to A-21 and A-24 for all-solid-state secondary batteries are negative electrode sheets for comparison.

<Manufacturing of electrode sheet for all-solid-state secondary battery (positive electrode sheet for all-solid-state secondary battery)>
(Preparation of composition c-1 for positive electrode)
180 zirconia beads having a diameter of 5 mm were placed in a 45 mL container made of zirconia (manufactured by Fritsch), 1.7 g of Li-PS-based glass synthesized in Synthesis Example 7 and 12.3 g of heptane as a dispersion medium (). Total amount) was put in. This container was set on a planetary ball mill P-7 (trade name) manufactured by Fritsch, and stirred at 25 ° C. at a rotation speed of 200 pm for 30 minutes. Then, in this container, _{8.0 g of LiNi 1/3} Co _1/3 Mn _1/3 O ₂ (NMC, manufactured by Aldrich) as the positive electrode active material and 0.2 g of acetylene black (AB) as the conductive auxiliary agent were added. 0.1 g of the fibrous binder F-2 was added, a container was set in the planetary ball mill P-7, and mixing was continued for 30 minutes at a temperature of 25 ° C. and a rotation speed of 200 rpm to prepare a positive electrode composition c-1.
(Preparation of Negative Electrode Compositions c-2 to c-5)
In the preparation of the negative electrode composition c-1, the composition for the positive electrode is the same as the preparation of the positive electrode composition c-1, except that the types of the positive electrode active material and the fibrous binder are changed as shown in Table 4. Objects c-2 to c-5 were prepared respectively.
The positive electrode composition c-5 is a negative electrode composition for comparison.

(Manufacturing of positive electrode sheets C-1 to C-5 for all-solid-state secondary batteries)
The positive electrode composition prepared above is applied to an aluminum foil (positive electrode current collector) having a thickness of 20 μm as a current collector with a baker-type applicator (trade name: SA-201, manufactured by Tester Sangyo Co., Ltd.). The composition was applied in an amount, heated at 80 ° C. for 1 hour, and further heated at 110 ° C. for 1 hour to dry the positive electrode composition. Then, using a heat press machine, the dried positive electrode composition (coated dry layer) is pressurized (20 MPa, 1 minute) while being heated at 120 ° C. to form a laminated structure of the positive electrode active material layer and the aluminum foil. C-1 to C-5 positive electrode sheets for all-solid-state secondary batteries were prepared.
The positive electrode sheet C-5 for an all-solid-state secondary battery is a positive electrode sheet for comparison.

<Table abbreviation>
Si: Silicon Sn: Tin SiO: Silicon monoxide C: Graphite NMC: LiNi _1/3 Co _1/3 Mn _1/3 O ₂
LCO: LiCoO ₂
L-P-S: Sulfide-based inorganic solid electrolyte (Li-P-S-based glass) synthesized in Synthesis Example 7.
LLZ: Li ₇ La ₃ Zr ₂ O ₁₂
AB: Acetylene Black PTFE: Polytetrafluoroethylene (manufactured by Aldrich)

<Manufacturing of all-solid-state secondary batteries>
(Preparation of electrode sheet)
An all-solid-state secondary battery was manufactured using the electrode sheet subjected to the following bending test.
In the bending test, the diameter of each of the manufactured negative electrode sheet for all-solid-state secondary battery and the positive electrode sheet for each all-solid-state secondary battery is described in <Evaluation 1: Film strength test of negative electrode sheet for all-solid-state secondary battery> described later. It was carried out in the same manner as in <Evaluation 1: Film strength test of negative electrode sheet for all-solid-state secondary battery> except that it was repeatedly bent three times using a 10 mm mandrel.

(Manufacturing of all-solid-state secondary batteries)
The solid electrolyte composition S-1 prepared above is applied on the negative electrode active material layer of each negative electrode sheet for an all-solid-state secondary battery subjected to the above bending test by an applicator so as to have the amount shown in Table 5. Then, it was heated at 80 ° C. for 1 hour and then dried at 110 ° C. for 6 hours. The sheet having the coated dry layer formed on the negative electrode active material layer is pressurized (30 MPa, 1 minute) while heating (120 ° C.) using a heat press machine to obtain a solid electrolyte layer, a negative electrode active material layer, and stainless steel. A sheet having a structure in which foils were laminated in this order was produced and cut into a disk shape having a diameter of 15 mm (referred to as a disk-shaped negative electrode sheet).
The positive electrode sheet for an all-solid-state secondary battery shown in Table 5 in which the bending test was performed was cut out in the shape of a disk having a diameter of 13 mm. After arranging (laminating) the disk-shaped negative electrode sheet and the disk-shaped positive electrode sheet so that the positive electrode active material layer of the disk-shaped positive electrode sheet and the solid electrolyte layer of the disk-shaped sheet face each other, a heat press machine is used. , Pressurized (40 MPa, 1 minute) while heating (120 ° C.). In this way, a laminated body for an all-solid-state secondary battery having a laminated structure shown in FIG. 1, that is, a structure in which an aluminum foil, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a SUS foil are laminated in this order was produced. .. The layer thickness of each layer is shown in Table 5.
As shown in FIG. 2, the laminate 12 for an all-solid-state secondary battery thus produced is placed in a stainless steel 2032-inch coin case 11 incorporating a spacer and a washer (not shown in FIG. 2), and 2032. By crimping the type coin case 11, No. All-solid-state secondary batteries 13 of 101 to 123 and c01 to c06 were manufactured.

<Evaluation 1: Film strength test of negative electrode sheet for all-solid-state secondary battery>
The film strength of the negative electrode active material layer in the negative electrode sheets A-1 to A-24 for all-solid-state secondary batteries was evaluated by a bending resistance test (based on JIS K5600-5-1) using a mandrel tester. The results are shown in the "Membrane Strength" column of Table 5.
Specifically, using a test piece cut out from a negative electrode sheet for an all-solid-state secondary battery into a strip shape having a width of 50 mm and a length of 100 mm, the negative electrode active material layer is placed on the opposite side of the mandrel (SUS foil is on the mandrel side). , And after setting the test piece so that the width direction is parallel to the axis of the mandrel and bending it 180 ° (once) along the outer peripheral surface of the mandrel, the presence or absence of cracks or cracks on the surface of the negative electrode active material layer. Was visually observed. This bending test is first performed using a mandrel with a diameter of 32 mm, and if no cracks or cracks have occurred, the diameter (mm) of the mandrel is 25, 20, 16, 12, 10, 8, 6, 5, The diameter was gradually reduced to 4, 3 and 2, and the diameter of the mandrel where the crack or crack first occurred was recorded.
The evaluation was made based on which of the following evaluation criteria included the diameter of the mandrel in which the crack or crack peeling first occurred (defect generation diameter). In this test, it is shown that the smaller the defect generation diameter, the stronger the solid particles are bound, and the better the film strength is, which follows the bending of the negative electrode active material, and the evaluation standard C or higher is the pass level.
-Evaluation criteria-
A: 5 mm or less B: 6 mm or 8 mm
C: 10 mm
D: 12 mm or 16 mm
E: 20 mm or 25 mm
F: 32 mm

When the film strength of the positive electrode sheets C-1 to C-5 for the all-solid-state secondary battery was evaluated in the same manner as in the above <Evaluation 1: Film strength test of the negative electrode sheet for the all-solid-state secondary battery>, the all-solid-state secondary battery was evaluated. The positive electrode sheets C-1 to C-4 for batteries were evaluated as A, and the positive electrode sheets C-5 for all-solid-state secondary batteries were evaluated as E.

<Evaluation 2: Battery performance test (discharge capacity) of all-solid-state secondary battery>
The discharge capacity of the all-solid-state secondary battery manufactured above was measured by a charge / discharge evaluation device "TOSCAT-3000" (trade name, manufactured by Toyo System Co., Ltd.). Specifically, the all-solid-state secondary battery was charged with a current value of 0.2 mA until the battery voltage reached 4.2 V, and then discharged at a current value of 0.2 mA until the battery voltage reached 3.0 V. This one charge and one discharge were charged and discharged as one cycle, and charging and discharging were repeated for three cycles. The discharge capacity in the third cycle was determined. This discharge capacity was converted into a surface area of the positive electrode active material layer ^{per 100 cm 2} , and evaluated according to which of the following evaluation criteria was included as the discharge capacity of the all-solid-state secondary battery. In this test, evaluation criteria C or higher is the passing level.
-Evaluation criteria-
A: 200mAh or more B: 160mAh or more, less than 200mAh C: 100mAh or more, less than 160mAh D: 60mAh or more, less than 100mAh E: less than 60mAh

<Evaluation 3: Battery performance test of all-solid-state secondary battery (discharge capacity density)>
For each all-solid secondary battery, the discharge capacity ( ^{converted value per 100 cm 2} surface area) measured in the above evaluation 2 is the total volume of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer (volume of both current collectors). The discharge capacity density was calculated by dividing by). In this test, evaluation criteria C or higher is the passing level.
-Evaluation criteria-
A: 180Ah / L or more B: 130Ah / L or more, less than 180Ah / L C: 90Ah / L or more, less than 130Ah / L D: 60Ah / L or more, less than 90Ah / L E: less than 60Ah / L

<Evaluation 4: Resistance measurement of all-solid-state secondary battery>
The resistance of each all-solid-state secondary battery manufactured above was measured by a charge / discharge evaluation device "TOSCAT-3000" (trade name, manufactured by Toyo System Co., Ltd.). Specifically, the all-solid-state secondary battery was charged with a current value of 0.2 mA until the battery voltage reached 4.2 V, and then discharged at a current value of 2.0 mA until the battery voltage reached 3.0 V. The battery voltage 10 seconds after the start of discharge was read and evaluated according to which of the following evaluation criteria was included. In this test, the higher the battery voltage, the smaller the resistance of the all-solid-state secondary battery, and the evaluation standard C or higher is the pass level.
-Evaluation criteria-
A: 4.1V or more B: 4.0V or more and less than 4.1V C: 3.8V or more and less than 4.0V D: 3.6V or more and less than 3.8V E: less than 3.6V

<Evaluation 5: Evaluation of battery life of all-solid-state secondary battery>
Each sample No. 10 samples of all-solid-state secondary batteries were manufactured, and the discharge capacity of 10 samples of all-solid-state secondary batteries was measured by the charge / discharge evaluation device "TOSCAT-3000" (trade name, manufactured by Toyo System Co., Ltd.). Life was evaluated. Specifically, each all-solid-state secondary battery is charged with a current value of 0.2 mA until the battery voltage reaches 4.2 V, and then discharged at a current value of 2.0 mA until the battery voltage reaches 3.0 V. bottom. This one charge and one discharge were set as one charge / discharge cycle, and charging / discharging was repeated for 100 cycles under the same conditions. The discharge capacity in the 5th charge / discharge cycle and the discharge capacity in the 100th charge / discharge cycle were obtained as follows. The average discharge capacity of the 5th cycle and the 100th cycle of the 6 samples of all-solid-state secondary batteries excluding the 2 samples above and below the performance of the 10 samples of batteries was calculated, respectively, and the average discharge capacity of the 5th cycle was obtained. The ratio of the average discharge capacity at the 100th cycle to the average discharge capacity at the 100th cycle ([average discharge capacity at the 100th cycle / average discharge capacity at the 5th cycle] × 100 (%)) was calculated. The evaluation was made according to which of the following evaluation criteria this ratio was included in. In this test, the higher the ratio, the longer the battery life, and the initial battery performance (discharge capacity and discharge capacity density) can be maintained even after repeated charging and discharging (even in long-term use). In this test, evaluation criteria C or higher is the passing level.
-Evaluation criteria-
A: 85% or more B: 75% or more, less than 85% C: 65% or more, less than 75% D: 55% or more, less than 65% E: less than 55%

The following can be seen from the results shown in Table 5.
The electrode sheets A-17 to A-21, A-24 and C-5 formed of the solid electrolyte composition (composition for electrodes) containing no fibrous binder specified in the present invention all have sufficient film strength. Does not show. Moreover, all-solid secondary batteries c01 to c06 provided with a positive electrode active material layer, a solid electrolyte layer and a negative electrode active material layer formed of a solid electrolyte composition or an electrode composition that does not contain the fibrous binder specified in the present invention. In each case, the discharge capacity, the discharge capacity density and the resistance are not sufficient, and the battery life is also inferior.
On the other hand, the electrode sheets A-1 to A-16, A-22 and A23 and C-1 to C formed of the solid electrolyte composition (composition for electrodes) containing the fibrous binder specified in the present invention. -4 indicates sufficient film strength. Further, an all-solid secondary battery 101- in which at least one layer of the positive electrode active material layer, the solid electrolyte layer and the negative electrode active material layer is formed of a solid electrolyte composition or an electrode composition containing the fibrous binder specified in the present invention. All of 123 are excellent in discharge capacity, discharge capacity density and resistance, and exhibit a long battery life.
As described above, the solid electrolyte composition containing the fibrous binder specified in the present invention suppresses an increase in interfacial resistance between solid particles in an all-solid secondary battery, firmly binds the solid particles, and has a small resistance. Moreover, excellent discharge capacity and discharge capacity density can be maintained even after repeated charging and discharging.

Further, the all-solid-state secondary batteries 106 and 109 to 112 and the like using Si, Sn or SiO as the negative electrode active material all have a discharge capacity as compared with the all-solid-state secondary battery 116 using graphite as the negative electrode active material layer. The density is increasing. Moreover, these all-solid-state secondary batteries maintain strong film strength and long battery life even though the volume change of the negative electrode active material layer becomes large. As described above, according to the preferred embodiment of the present invention, it is possible to solve the problems (bonding property of solid particles and battery life) peculiar to the negative electrode active material layer having a large volume change. On the other hand, the all-solid-state secondary battery c06 using a fluororesin as the binder and the all-solid-state secondary batteries c02 and c05 using a particulate binder or a solution binder all have the binding property of solid particles and the binding property of solid particles. It can be seen that the problem peculiar to the negative electrode active material layer, which is inferior in battery life and has a large volume change, cannot be solved.

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

This application claims priority based on Japanese Patent Application No. 2018-152285, which was filed in Japan on August 13, 2018, which is referred to herein and is described herein. Take in as a part.

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 Working part 10 All-solid secondary battery 11 2032 type coin case 12 All-solid secondary battery laminate 13 All-solid Secondary battery

Claims (12)

Inorganic solid electrolytes with ionic conductivity of metals belonging to Group 1 or Group 2 of the Periodic Table
A binder made of a polymer satisfying the following properties (P1) and (P2), and a fibrous binder satisfying the following properties (B1) to (B3).
A solid electrolyte composition comprising a dispersion medium.
(P1) Elastic modulus: 0.1 to 1,000 MPa
(P2) Elastic deformation rate: 0.01 to 10,000%
(B1) Average diameter D: 0.001 to 10 μm
(B2) Average length L: 0.1 μm to 1,000 mm
(B3) Ratio of average length L to average diameter D L / D: 10 to 100,000 The solid electrolyte composition according to claim 1, wherein the polymer has at least one component containing an aliphatic hydrocarbon group having 5 or more carbon atoms. The solid electrolyte composition according to claim 1 or 2, wherein the polymer has at least one functional group selected from the following functional group group (a).
Functional group (a)
Acidic functional group, basic functional group, hydroxy group, cyano group, alkoxysilyl group, aryl group, heteroaryl group, aliphatic hydrocarbon ring group having 3 or more rings condensed. The solid electrolyte composition according to any one of claims 1 to 3, wherein the polymer has a constituent component represented by any of the following formulas (1-1) to (1-6).

In the formula, R ¹ and R ² are hydrogen atoms; an alkyl group; a substituent containing a polyethylene oxide chain, a polypropylene oxide chain, a polycarbonate chain or a polyester chain and having a mass average molecular weight of 50 or more and 200,000 or less; an alcoholic hydroxyl group. A monovalent substitution having a phenolic hydroxyl group, a sulfanyl group, a carboxy group, a sulfonic acid group, a phosphoric acid group, a nitrile group, an amino group, a twin ion-containing group, or a group consisting of a metal compound having a hydroxy group or an alkoxide group. Group; or; Indicates a substituent having a carbon-carbon unsaturated group.
R ³ is a hydrocarbon chain; a linking group containing a polyethylene oxide chain, a polypropylene oxide chain, a polycarbonate chain or a polyester chain and having a mass average molecular weight of 50 or more and 200,000 or less; an alcoholic hydroxyl group, a phenolic hydroxyl group, a sulfanyl group, a carboxy group. A linking group having a group consisting of a group, a sulfonic acid group, a phosphoric acid group, a nitrile group, an amino group, a twin ion-containing group, or a metal compound having a hydroxy group or an alkoxide group; or; a carbon-carbon unsaturated group. The linking group having is shown.
R ⁴ represents an aromatic or aliphatic linking group. The solid electrolyte composition according to any one of claims 1 to 4, which contains an active material. The solid electrolyte composition according to claim 5, wherein the active material is an active material that can be alloyed with lithium. The solid electrolyte composition according to any one of claims 1 to 6, wherein the polymer has a glass transition temperature of −120 to 80 ° C. The solid electrolyte composition according to any one of claims 1 to 7, wherein the inorganic solid electrolyte is a sulfide-based solid electrolyte. A solid electrolyte-containing sheet having a layer composed of the solid electrolyte composition according to any one of claims 1 to 8. An electrode sheet for an all-solid-state secondary battery having an active material layer composed of the solid electrolyte composition according to claim 5 or 6. An all-solid-state secondary battery including a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order.
The all-solid-state rechargeable battery is a layer in which at least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer is composed of the solid electrolyte composition according to any one of claims 1 to 8. Next battery. The all-solid-state secondary battery according to claim 11, wherein the negative electrode active material layer is a layer composed of the solid electrolyte composition according to claim 5 or 6.

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