Inorganic solid electrolyte-containing composition, sheet for all-solid-state secondary batteries, all-solid-state secondary battery, method for producing sheet for all-solid-state secondary batteries, and method for producing all-solid-state secondary battery

Abstract

Provided are: an inorganic solid electrolyte-containing composition; a sheet for all-solid-state secondary batteries; an all-solid-state secondary battery; a method for producing the sheet; and a method for producing the all-solid-state secondary battery. The inorganic solid electrolyte-containing composition contains an inorganic solid electrolyte, a polymer binder, and a dispersion medium, wherein the polymer binder contains a polymer having: a structural unit (A) derived from a disubstituted vinyl monomer having a homopolymer Tg of lower than 50°C; and at least one structural unit (B) selected from structural units derived from (meth)acrylamide having a homopolymer Tg of 50°C or higher, the total content of the structural unit (A) and the structural unit (B) being 80 mass% or more, and the polymer binder being soluble in the dispersion medium.

Description

Inorganic solid electrolyte-containing composition, sheet for all-solid-state secondary battery, all-solid-state secondary battery, and method for manufacturing sheet for all-solid-state secondary battery and all-solid-state secondary battery

[0001] The present invention relates to an inorganic solid electrolyte-containing composition, a sheet for an all-solid-state secondary battery, an all-solid-state secondary battery, and a method for producing the sheet for an all-solid-state secondary battery and the all-solid-state secondary battery.

[0002] All-solid-state secondary batteries, in which the negative electrode, electrolyte, and positive electrode are all solid, can significantly improve the safety and reliability that are issues with secondary batteries that use organic electrolytes. It is also believed that they can achieve longer life. Furthermore, all-solid-state secondary batteries can be configured with electrodes and electrolytes directly arranged in series. This allows for higher energy density than secondary batteries that use organic electrolytes, and they are expected to be used in electric vehicles, large-scale storage batteries, and other applications.

[0003] In such all-solid-state secondary batteries, inorganic solid electrolytes, active materials, conductive additives, etc. are used as materials for forming constituent layers (such as a solid electrolyte layer, a negative electrode active material layer, and a positive electrode active material layer). In recent years, inorganic solid electrolytes, particularly oxide-based inorganic solid electrolytes and sulfide-based inorganic solid electrolytes, have been expected as electrolyte materials with high ionic conductivity approaching that of organic electrolyte solutions. In consideration of improving productivity, constituent layers using inorganic solid electrolytes are typically formed using a material (constituent layer-forming material) containing an inorganic solid electrolyte and a binder. For example, Patent Document 1 describes "an inorganic solid electrolyte-containing composition containing an inorganic solid electrolyte having ionic conductivity for a metal belonging to Group 1 or Group 2 of the periodic table, a polymer binder, and a dispersion medium, wherein the inorganic solid electrolyte-containing composition has an adsorption rate of the polymer binder to the inorganic solid electrolyte in the dispersion medium of less than 60%."

[0004] International Publication No. 2021 / 039468

[0005] Because the constituent layers of all-solid-state secondary batteries are formed from solid particles (inorganic solid electrolytes, active materials, conductive additives, etc.), the interfacial contact between the solid particles and the current collector is constrained. As a result, the interfacial resistance is likely to increase, and the solid particles cannot be firmly bonded to each other. This increase in interfacial resistance not only increases the battery resistance (decreased ionic conductivity) of all-solid-state secondary batteries, but also leads to a deterioration in cycle performance. Furthermore, the insufficient adhesion between the solid particles leads to a further deterioration in cycle performance. The increase in resistance at interfaces, batteries, etc., which is a cause of battery performance degradation, is due not only to the interfacial contact between the solid particles, but also to the uneven distribution (arrangement) of the solid particles in the constituent layers and the surface flatness of the constituent layers. Therefore, when forming a constituent layer using a constituent layer-forming material, the constituent layer-forming material is required to have the property of stably maintaining excellent dispersibility of solid particles immediately after preparation (initial dispersibility) (dispersion stability), and the property of having a moderate viscosity and being able to form a good coating film with high fluidity (handleability). Moreover, in recent years, research and development into improving the performance and practical application of electric vehicles has progressed rapidly, and the performance required of all-solid-state secondary batteries has also increased. To realize high-performance all-solid-state secondary batteries, the property of maintaining battery capacity even when repeatedly charged at a higher potential than usual (e.g., 4.4 to 4.5 V) (also referred to in the present invention as "high-potential cycling characteristic") has become necessary. However, Patent Document 1 does not consider the polymer binder used in combination with the inorganic solid electrolyte and the dispersion medium in inorganic solid electrolyte-containing compositions from the above-mentioned perspective.

[0006] An object of the present invention is to provide an inorganic solid electrolyte-containing composition that exhibits excellent dispersion stability and handleability, and that, when used as a material for forming a constituent layer of an all-solid-state secondary battery, enables the realization of an all-solid-state secondary battery that has low resistance and also excellent high-potential cycle characteristics. Another object of the present invention is to provide a sheet for an all-solid-state secondary battery, an all-solid-state secondary battery, and a method for producing the sheet for an all-solid-state secondary battery and the all-solid-state secondary battery, using this inorganic solid electrolyte-containing composition.

[0007] The present inventors have conducted extensive research into polymer binders used in combination with inorganic solid electrolytes and dispersion media in inorganic solid electrolyte-containing compositions. As a result, they have found that by constructing the polymer binder from a polymer containing a specific content of a structural unit (A) derived from a disubstituted vinyl monomer having a homopolymer glass transition temperature of less than 50°C and at least one structural unit (B) selected from structural units derived from styrene, structural units derived from vinyl ethers, and structural units derived from (meth)acrylamide having a homopolymer glass transition temperature of 50°C or higher, and then imparting the polymer binder with the property of dissolving in a dispersion media, excellent dispersion stability and handleability can be achieved. Furthermore, they have found that by using this inorganic solid electrolyte-containing composition as a constituent layer-forming material, it is possible to realize a sheet for an all-solid-state secondary battery having a low-resistance constituent layer in which solid particles are firmly adhered (bound), and further an all-solid-state secondary battery having low resistance and excellent high-potential cycle characteristics. The present invention was completed through further research based on these findings.

[0008] That is, the above-mentioned problems have been solved by the following means: [1] An inorganic solid electrolyte-containing composition containing an inorganic solid electrolyte having ionic conductivity for a metal belonging to Group 1 or 2 of the periodic table, a polymer binder, and a dispersion medium, wherein the polymer binder has structural units (A) derived from a disubstituted vinyl monomer having a homopolymer glass transition temperature of less than 50°C, and at least one structural unit (B) selected from structural units derived from styrene, structural units derived from vinyl ether, and structural units derived from (meth)acrylamide having a homopolymer glass transition temperature of 50°C or higher, the total content of structural units (A) and (B) being 80 mass% or more, and the inorganic solid electrolyte-containing composition is soluble in the dispersion medium. [2] The inorganic solid electrolyte-containing composition according to [1], wherein the polymer has at least one polar functional group selected from the following functional group group (a): <Functional Group (a)> Sulfonic acid group, phosphoric acid group, phosphonic acid group, hydroxyl group, carboxyl group, dicarboxylic acid group, thiol group, ether group, ester group, amide group, urethane group, urea group, imide group, fluoroalkyl group, and salts thereof. [3] The inorganic solid electrolyte-containing composition according to [1] or [2], wherein the polymer has a structural unit having at least one polar functional group selected from the following functional group group (a): <Functional Group (a)> Sulfonic acid group, phosphoric acid group, phosphonic acid group, hydroxyl group, carboxyl group, dicarboxylic acid group, thiol group, ether group, ester group, amide group, urethane group, urea group, imide group, fluoroalkyl group, and salts thereof. [4] The inorganic solid electrolyte-containing composition according to any one of [1] to [3], wherein the structural unit (B) comprises a structural unit derived from (meth)acrylamide. [5] The inorganic solid electrolyte-containing composition according to any one of [1] to [4], wherein the glass transition temperature of the polymer is -20°C or higher. [6] The inorganic solid electrolyte-containing composition according to any one of [1] to [5], wherein the structural unit (A) comprises a structural unit derived from a 1,1-disubstituted vinyl monomer. [7] The inorganic solid electrolyte-containing composition according to any one of [1] to [6], wherein the structural unit (A) comprises a structural unit derived from a methacrylic acid ester monomer.[8] The inorganic solid electrolyte-containing composition according to any one of [1] to [7], wherein the total content of the structural unit (A) and the structural unit (B) in the polymer is 95% by mass or more. [9] The inorganic solid electrolyte-containing composition according to any one of [1] to [8], which contains an active material.

[10] The inorganic solid electrolyte-containing composition according to any one of [1] to [9], wherein the inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.

[11] A sheet for an all-solid-state secondary battery, having a layer formed using the inorganic solid electrolyte-containing composition according to any one of [1] to

[10] above.

[12] An all-solid-state secondary battery comprising, in this order, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, wherein at least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is a layer formed using the inorganic solid electrolyte-containing composition according to any one of [1] to

[10] above.

[13] A method for producing a sheet for an all-solid-state secondary battery, which comprises forming a film from the inorganic solid electrolyte-containing composition according to any one of [1] to

[10] above.

[14] A method for producing an all-solid-state secondary battery, which comprises producing an all-solid-state secondary battery via the method according to

[13] above.

[0009] The present invention provides an inorganic solid electrolyte-containing composition that exhibits excellent dispersion stability and handleability, and that, when used as a material for forming a constituent layer of an all-solid-state secondary battery, enables the realization of an all-solid-state secondary battery that has low resistance and excellent high-potential cycle characteristics. The present invention also provides a sheet for an all-solid-state secondary battery and an all-solid-state secondary battery that use this inorganic solid electrolyte-containing composition, as well as methods for manufacturing the sheet for an all-solid-state secondary battery and the all-solid-state secondary battery. The above and other features and advantages of the present invention will become more apparent from the following description, with reference to the accompanying drawings, as appropriate.

[0010] Fig. 1 is a longitudinal sectional view schematically showing an all-solid-state secondary battery according to a preferred embodiment of the present invention, and Fig. 2 is a longitudinal sectional view schematically showing a coin-type all-solid-state secondary battery fabricated in Examples.

[0011] In the present invention, when describing the content, physical properties, etc. of a component by indicating a numerical range, if the upper and lower limits of the numerical range are described separately, any of the upper and lower limits can be appropriately combined to form a specific numerical range. On the other hand, when describing multiple numerical ranges expressed using "to", the upper and lower limits forming the numerical range are not limited to the combination of the specific upper and lower limits written before and after "to" as a specific numerical range, but can be a numerical range obtained by appropriately combining the upper and lower limits of each numerical range. Note that in the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the upper and lower limits.

[0012] In the present invention, the expression "compound" (for example, when referring to a compound by adding "compound" to the end of the name) refers to the compound itself, as well as its salts and ions. It also includes derivatives that have been partially modified, such as by introducing a substituent, as long as the effects of the present invention are not impaired. In the present invention, for substituents, linking groups, etc. (hereinafter referred to as "substituents, etc.") that are not specified as substituted or unsubstituted, it means that the group may have an appropriate substituent. Therefore, even when simply referring to a YYY group in the present invention, this YYY group encompasses not only an embodiment in which it has no substituent, but also an embodiment in which it has a substituent. This also applies to compounds in which substituted or unsubstituted is not specified. A preferred substituent is, for example, the substituent Z described below. In the present invention, when there are multiple substituents, etc., designated by a specific symbol, or when multiple substituents, etc. are specified simultaneously, it means that the respective substituents, etc., may be the same or different from each other. Furthermore, unless otherwise specified, when multiple substituents, etc., are adjacent, they may be linked to each other or fused to form a ring. In the present invention, "(meth)acrylic" means one or both of acrylic and methacrylic. The same applies to (meth)acrylates.

[0013] In the present invention, the term "polymer binder" (sometimes simply referred to as "binder") refers to a binder composed of a polymer, and includes both the polymer itself and binders composed (formed) containing a polymer. In the present invention, "polymer" refers to a polymer, but is synonymous with the term "polymer compound." In the present invention, the main chain of a polymer (including a polymer chain) refers to a linear molecular chain in which all other molecular chains constituting the polymer can be considered as branched chains or pendant groups relative to the main chain. While this depends on the weight-average molecular weight of the branched chains considered as branched chains or pendant groups, typically, the longest chain among the molecular chains constituting the polymer is the main chain. However, terminal groups at the polymer ends are not included in the main chain. In contrast, the side chain of a polymer refers to a branched chain other than the main chain, and includes short chains and long chains (graft chains). The terminal group of a polymer is not particularly limited and can be an appropriate group depending on the polymerization method, etc. Examples of terminal groups include hydrogen atoms, alkyl groups, aryl groups, hydroxy groups, and even residues of polymerization initiators.

[0014] [Inorganic Solid Electrolyte-Containing Composition] The inorganic solid electrolyte-containing composition of the present invention contains an inorganic solid electrolyte having ionic conductivity for a metal belonging to Group 1 or 2 of the Periodic Table, a polymer binder, and a dispersion medium. This polymer binder is formed by containing a polymer having specific contents of the structural unit (A) and the structural unit (B) described below, and exhibits the property of dissolving in the dispersion medium. An inorganic solid electrolyte-containing composition containing the above components exhibits excellent dispersion stability and handleability. The excellent dispersion stability and handleability are maintained even when the solid content in the inorganic solid electrolyte-containing composition is increased. Furthermore, by using the inorganic solid electrolyte-containing composition of the present invention as a material for forming a constituent layer of an all-solid-state secondary battery, solid particles can be firmly adhered (bound), thereby realizing an all-solid-state secondary battery that has low resistance and excellent high-voltage cycle characteristics.

[0015] Although the details of the reason are not yet clear, it is thought to be as follows. A binder containing a polymer (sometimes referred to as the "polymer of the present invention") having a specific content of the structural unit (A) and the structural unit (B) described below is dissolved in the dispersion medium in the inorganic solid electrolyte-containing composition, and the binder particles are less likely to aggregate and adhere to each other, improving dispersibility. Furthermore, the binder can be appropriately adsorbed to the solid particles, suppressing (re)aggregation and precipitation of the solid particles in the dispersion medium and thereby highly dispersing them. Therefore, even if the solid content is increased, excellent initial dispersibility can be maintained over time, and even solid particles that have once aggregated or precipitated can reproduce the excellent initial dispersibility immediately after preparation, and it is thought that it exhibits appropriate fluidity. When a constituent layer is formed from such an inorganic solid electrolyte-containing composition, uneven distribution of the solid particles can be suppressed, and the solid particles can be firmly adhered (bonded) to form sufficient conductive paths (ionic conductive paths and electronic conductive paths), and it is also thought that the occurrence of surface roughness due to insufficient or excessive flow, as well as surface roughness due to clogging of the discharge part during application, can be suppressed. Such a constituent layer can suppress the generation of overcurrent during charge and discharge of an all-solid-state secondary battery and prevent degradation of the solid particles. Furthermore, a polymer binder containing the polymer of the present invention solidifies while maintaining excellent dispersibility in the inorganic solid electrolyte-containing composition when dried after application, and is resistant to degradation even when the all-solid-state secondary battery is charged at a high voltage. As a result, it is believed that the adhesion state of the solid particles can be maintained for a long period of time. Therefore, the inorganic solid electrolyte-containing composition of the present invention can be used to produce an all-solid-state secondary battery sheet having a constituent layer with low resistance that can exhibit excellent high-voltage cycle characteristics when incorporated into an all-solid-state secondary battery, and can also produce an all-solid-state secondary battery that also exhibits low resistance and excellent high-voltage cycle characteristics. The all-solid-state secondary battery of the present invention also has an excellent characteristic of maintaining battery capacity even when repeatedly charged at a normal potential (e.g., less than 4.4 V) (this characteristic is referred to as "normal potential cycle characteristic" when distinguished from the high-potential cycle characteristic). In the present invention, "cycle characteristic" includes both normal potential cycle characteristic and high-potential cycle characteristic.

[0016] The inorganic solid electrolyte-containing composition of the present invention is preferably a slurry, particularly a high-concentration slurry, in which solid particles are dispersed in a dispersion medium. Furthermore, the inorganic solid electrolyte-containing composition of the present invention is preferably a non-aqueous composition. In the present invention, the non-aqueous composition includes not only an embodiment that does not contain water, but also an embodiment in which the water content (also referred to as water content) is preferably 500 ppm or less. In a non-aqueous composition, the water content is more preferably 200 ppm or less, even more preferably 100 ppm or less, and particularly preferably 50 ppm or less. When the inorganic solid electrolyte-containing composition is a non-aqueous composition, deterioration of the inorganic solid electrolyte can be suppressed. The water content refers to the amount of water contained in the inorganic solid electrolyte-containing composition (mass ratio relative to the inorganic solid electrolyte-containing composition), and is specifically a value measured by filtering through a 0.02 μm membrane filter and using Karl Fischer titration.

[0017] The inorganic solid electrolyte-containing composition of the present invention exhibits the above-mentioned excellent properties and can therefore be preferably used as a material for forming a sheet for an all-solid-state secondary battery and a constituent layer of the all-solid-state secondary battery. Among the constituent layers, it can be preferably used as a material for forming an active material layer, particularly a positive electrode active material layer and a negative electrode active material layer containing a negative electrode active material that expands and contracts greatly due to charge and discharge.

[0018] The inorganic solid electrolyte-containing composition of the present invention also includes an embodiment containing an active material and the like in addition to the inorganic solid electrolyte (the composition of this embodiment is referred to as an "electrode composition"). Hereinafter, the components contained in the inorganic solid electrolyte-containing composition of the present invention and the components that can be contained therein will be described.

[0019] [Inorganic Solid Electrolyte] The inorganic solid electrolyte-containing composition of the present invention contains an inorganic solid electrolyte. In the present invention, the inorganic solid electrolyte refers to an inorganic solid electrolyte, and the solid electrolyte refers to a solid electrolyte capable of moving ions therein. Since the inorganic solid electrolyte does not contain an organic substance as the main ion-conducting material, it is clearly distinguished from organic solid electrolytes (polymer electrolytes typified by polyethylene oxide (PEO) and the like, and organic electrolyte salts typified by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and the like). In addition, since the inorganic solid electrolyte is solid in a steady state, it is not usually dissociated or liberated into cations and anions. In this respect, the inorganic solid electrolyte salt (LiPF ) dissociated or liberated into cations and anions in an electrolytic solution or a polymer is not dissociated or liberated into cations and anions. ６ , LiBF ４ , lithium bis(fluorosulfonyl)imide (LiFSI), LiCl, etc.). The inorganic solid electrolyte is not particularly limited as long as it has ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and generally does not have electronic conductivity. When the all-solid-state secondary battery of the present invention is a lithium-ion battery, the inorganic solid electrolyte preferably has ionic conductivity of lithium ions. The inorganic solid electrolyte can be appropriately selected from solid electrolyte materials commonly used in all-solid-state secondary batteries. Examples of inorganic solid electrolytes include (i) sulfide-based inorganic solid electrolytes, (ii) oxide-based inorganic solid electrolytes, (iii) halide-based inorganic solid electrolytes, and (iv) hydride-based inorganic solid electrolytes. In the present invention, a sulfide-based inorganic solid electrolyte, which is generally prone to deterioration and decomposition, can be used, and a better interface can be formed between solid particles, effectively suppressing an increase in interfacial resistance.

[0020] (i) Sulfide-based inorganic solid electrolyte The sulfide-based inorganic solid electrolyte preferably contains sulfur atoms, has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S, and P as elements and has lithium ion conductivity, but may contain elements other than Li, S, and P as appropriate.

[0021] Examples of sulfide-based inorganic solid electrolytes include lithium ion conductive inorganic solid electrolytes having a composition represented by the following formula (S1): ａ１ M ｂ１ P ｃ１ S ｄ１ A ｅ１ (S1) In formula (S1), L represents an element selected from Li, Na, and K, and Li is 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 represent the composition ratio of each element, and a1:b1:c1:d1:e1 satisfies the ratio of 1-12:0-5:1:2-12:0-10. a1 is preferably 1-9, and more preferably 1.5-7.5. b1 is preferably 0-3, and more preferably 0-1. d1 is preferably 2.5-10, and more preferably 3.0-8.5. e1 is preferably 0-5, and more preferably 0-3.

[0022] The composition ratio of each element can be controlled by adjusting the blending amounts of raw material compounds when producing the sulfide-based inorganic solid electrolyte, as described below.

[0023] The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystallized (glass-ceramic), or may be only partially crystallized. For example, Li-P-S-based glass containing Li, P, and S, or Li-P-S-based glass-ceramic containing Li, P, and S can be used. The sulfide-based inorganic solid electrolyte may be, for example, lithium sulfide (Li ２ S), phosphorus sulfide (e.g., diphosphorus pentasulfide (P ２ S ５)), elemental phosphorus, elemental sulfur, sodium sulfide, hydrogen sulfide, lithium halides (e.g., LiI, LiBr, LiCl), and sulfides of the elements represented by M (e.g., SiS ２ , SnS, GeS ２ ) can be produced by reacting at least two or more raw materials.

[0024] Li in Li-P-S glass and Li-P-S glass ceramics ２ S and P ２ S ５ The ratio of Li ２ S:P ２ S ５ The molar ratio of Li is preferably 60:40 to 90:10, more preferably 68:32 to 78:22. ２ S and P ２ S ５ By setting the ratio to this range, the lithium ion conductivity can be made high. Specifically, the lithium ion conductivity is preferably set to 1×10 －４ S / cm or more, more preferably 1×10 －３ There is no particular upper limit, but it can be 1 × 10 －１ It is practical to have a viscosity of 200 S / cm or less.

[0025] As a specific example of a sulfide-based inorganic solid electrolyte, a 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-P２ 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 ２S ３ , Li ２ S-SiS ２ -P ２ S ５ , Li ２ S-SiS ２ -P ２ S ５ - LiI, Li ２ S-SiS ２ - LiI, Li ２ S-SiS ２ -Li ４ SiO ４ , Li ２ S-SiS ２ -Li ３ P.O. ４ , Li １０ GeP ２ S １２ However, the mixing ratio of each raw material is not important. 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 becomes possible, and the manufacturing process can be simplified.

[0026] (ii) Oxide-based inorganic solid electrolyte The oxide-based inorganic solid electrolyte preferably contains oxygen atoms, has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation. The oxide-based inorganic solid electrolyte preferably has an ionic conductivity of 1×10 －６ S / cm or more, and 5×10 －６ S / cm or more is more preferable, and 1×10 －５ The upper limit is not particularly limited, but it is preferably 1 × 10 －１ It is practical to have a viscosity of 200 S / cm or less.

[0027] Specific examples of the compound include Li ｘａ La ｙａ TiO ３ [xa satisfies 0.3≦xa≦0.7, and ya satisfies 0.3≦ya≦0.7.] (LLT); Li ｘｂ La ｙｂ Zr ｚｂ Mｂｂ ｍｂ O ｎｂ (M ｂｂ is one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn. xb satisfies 5≦xb≦10, yb satisfies 1≦yb≦4, zb satisfies 1≦zb≦4, mb satisfies 0≦mb≦2, and nb satisfies 5≦nb≦20; Li ｘｃ B ｙｃ M ｃｃ ｚｃ O ｎｃ (M ｃｃ is one or more elements selected from C, S, Al, Si, Ga, Ge, In, and Sn. xc satisfies 0<xc≦5, yc satisfies 0<yc≦1, zc satisfies 0<zc≦1, and nc satisfies 0<nc≦6; Li ｘｄ (Al, Ga) ｙｄ (Ti, Ge) ｚｄ Si ａｄ P ｍｄ O ｎｄ (xd satisfies 1≦xd≦3, yd satisfies 0≦yd≦1, zd satisfies 0≦zd≦2, ad satisfies 0≦ad≦1, md satisfies 1≦md≦7, and nd satisfies 3≦nd≦13); Li （３－２ｘｅ） M ｅｅ ｘｅ D ｅｅ O(xe represents a number between 0 and 0.1, and M ｅｅ represents a divalent metal atom. ｅｅ represents a halogen atom or a combination of two or more halogen atoms; Li ｘｆ Si ｙｆ O ｚｆ (xf satisfies 1≦xf≦5, yf satisfies 0<yf≦3, and zf satisfies 1≦zf≦10); Li ｘｇ S ｙｇ O ｚｇ (xg satisfies 1≦xg≦3, yg satisfies 0<yg≦2, and zg satisfies 1≦zg≦10); Li ３ BO ３ Li ３ BO ３ -Li ２ SO ４ Li ２ Alumni２ O ３ -P ２ O ５ Li ２ O—SiO ２ Li ６ BaLa ２ Ta ２ O １２ Li ３ P.O. （４－３／２ｗ） N ｗ (w is w<1); Li having a LISICON (Lithium super ionic conductor) type crystal structure ３．５ Zn ０．２５ GeO ４ La having a perovskite crystal structure ０．５５ Li ０．３５ TiO ３ LiTi having a NASICON (sodium super ionic conductor) type crystal structure ２ P ３ O １２ Li １＋ｘｈ＋ｙｈ (Al, Ga) ｘｈ (Ti, Ge) ２－ｘｈ Si ｙｈ P ３－ｙｈ O １２ (xh satisfies 0≦xh≦1, and yh satisfies 0≦yh≦1); Li having a garnet-type crystal structure ７ La ３ Zr ２ O １２ (LLZ), etc. Phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li ３ P.O. ４ ) LiPON, in which part of the oxygen element of lithium phosphate is replaced with nitrogen element; LiPOD １ (D １ is preferably one or more elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au. １ ON (A １ is one or more elements selected from Si, B, Ge, Al, C and Ga.) can also be preferably used.

[0028] (iii) Halide-based inorganic solid electrolyte The halide-based inorganic solid electrolyte is preferably a compound containing a halogen atom, having ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and having electronic insulation. The halide-based inorganic solid electrolyte is not particularly limited, but examples thereof include LiCl, LiBr, LiI, and Li described in ADVANCED MATERIALS, 2018, 30, 1803075. ３ YBr ６ , Li ３ YCl ６ Among them, Li ３ YBr ６ , Li ３ YCl ６ is preferred.

[0029] (iv) Hydride-based inorganic solid electrolyte The hydride-based inorganic solid electrolyte is preferably a compound that contains hydrogen atoms, has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation. The hydride-based inorganic solid electrolyte is not particularly limited, but examples thereof include LiBH ４ , Li ４ (BH ４ ) ３ I, 3LiBH ４ -LiCl, etc.

[0030] The inorganic solid electrolyte is preferably in a particulate form in the inorganic solid electrolyte-containing composition. In this case, the particle diameter (volume average particle diameter) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.1 μm or more. The upper limit is preferably 100 μm or less, more preferably 50 μm or less. The particle diameter of the inorganic solid electrolyte is measured by the following procedure. Particles of the inorganic solid electrolyte are diluted with water (heptane in the case of substances unstable in water) in a 20 mL sample bottle to prepare a 1 mass % dispersion. The diluted dispersion sample is irradiated with 1 kHz ultrasound for 10 minutes and used for testing immediately thereafter. Using this dispersion sample, data is acquired 50 times using a quartz measurement cell at a temperature of 25°C using a laser diffraction / scattering particle size distribution analyzer LA-920 (trade name, manufactured by HORIBA Corporation), to obtain the volume average particle diameter. For other detailed conditions, etc., refer to the description in Japanese Industrial Standards (JIS) Z 8828:2013 "Particle size analysis - dynamic light scattering method." Five samples are prepared for each level, and the average value is used.

[0031] The method for adjusting the particle size is not particularly limited, and known methods can be applied, such as a method using a conventional pulverizer or classifier. Suitable pulverizers or classifiers include, for example, a mortar, a ball mill, a sand mill, a vibration ball mill, a satellite ball mill, a planetary ball mill, a swirling airflow jet mill, or a sieve. Wet pulverization can be performed in the presence of a dispersion medium such as water or methanol. Classification is preferably performed to obtain the desired particle size. Classification is not particularly limited, and can be performed using a sieve, an air classifier, or the like. Both dry and wet classification methods can be used.

[0032] The inorganic solid electrolyte-containing composition may contain one or more inorganic solid electrolytes. The content of the inorganic solid electrolyte in the inorganic solid electrolyte-containing composition is not particularly limited, but in terms of the dispersion state of the solid particles and resistance, it is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of the solid content. 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 inorganic solid electrolyte-containing composition contains an active material described below, the content of the inorganic solid electrolyte in the inorganic solid electrolyte-containing composition is preferably such that the total content of the active material and the inorganic solid electrolyte is within the above range. In the present invention, the solid content (solid component) refers to components that do not volatilize or evaporate when the inorganic solid electrolyte-containing composition is dried at 150°C under a nitrogen atmosphere at an atmospheric pressure of 1 mmHg for 6 hours. Typically, it refers to components other than the dispersion medium described below.

[0033] [Polymer Binder] The polymer binder contained in the inorganic solid electrolyte-containing composition of the present invention contains the polymer of the present invention described below and has the property of dissolving in a dispersion medium as described below. The polymer binder may contain one or more types of polymer of the present invention. In the present invention, when a polymer binder contains the polymer of the present invention, this encompasses both a binder consisting of the polymer of the present invention itself and a binder containing the polymer of the present invention and other components. Other components that may be contained in the binder are not particularly limited, but include polymers other than the polymer of the present invention, synthesis by-products of the polymer of the present invention, decomposition products (residues) of polymerization catalysts, etc., and remaining synthetic solvents. Examples of polymers other than the polymer of the present invention include polymer binders commonly used as binders for all-solid-state secondary batteries (sometimes referred to as "other polymer binders" in the present invention), and details will be described below. The content of the polymer of the present invention in the polymer binder is appropriately set within a range that achieves the effects of the present invention, and can be, for example, 90% by mass or more. On the other hand, the total content of other components in the polymer binder is appropriately set within a range that does not impair the effects of the present invention, and can be, for example, 10% by mass or less.

[0034] In the inorganic solid electrolyte-containing composition of the present invention, the polymer binder (the polymer of the present invention contained in the polymer binder) is believed to exhibit the function of dispersing the solid particles in the dispersion medium by adsorbing to the solid particles and interposing between the solid particles. Here, the adsorption of the polymer binder to the solid particles is not particularly limited, but includes not only physical adsorption but also chemical adsorption (adsorption by chemical bond formation, adsorption by electron transfer, etc.). The dispersion stability and handleability exhibited by the polymer binder are also exhibited even when the solid content concentration is increased. The solid content concentration of the inorganic solid electrolyte-containing composition of the present invention is not particularly limited and can typically be 20 to 80 mass%, preferably 30 to 75 mass%, and more preferably 40 to 70 mass% at 25°C. On the other hand, the inorganic solid electrolyte-containing composition of the present invention can also be a high-concentration composition in which the solid content concentration is set higher than conventional compositions. For example, the lower limit of the solid content concentration of the high-concentration composition can be set to 50 mass% or more at 25°C, for example, 60 mass% or more. The upper limit is less than 100% by mass, for example, 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0035] On the other hand, the polymer binder (the polymer of the present invention) functions as a binder that firmly binds solid particles together in a constituent layer formed from the inorganic solid electrolyte-containing composition. It also functions as a binder that firmly binds solid particles to a substrate such as a current collector. In the inorganic solid electrolyte-containing composition, the polymer binder may or may not have the function of binding solid particles together.

[0036] <Polymer of the Invention> The polymer contained in the polymer binder (polymer of the invention) has, as essential structural units (also referred to as structural components), a structural unit (A) derived from a disubstituted vinyl monomer whose homopolymer has a glass transition temperature of less than 50°C, and at least one structural unit (B) selected from a structural unit derived from styrene, a structural unit derived from a vinyl ether, and a structural unit derived from (meth)acrylamide whose homopolymer has a glass transition temperature of 50°C or higher. Furthermore, the polymer of the invention has a total content of the structural unit (A) and the structural unit (B) of 80 mass% or more of the total mass of the polymer. The polymer of the invention only needs to have the structural unit (A) and the structural unit (B) in specific contents, and may also have a structural unit that does not correspond to either the structural unit (A) or the structural unit (B) (referred to as "structural unit (C)" in the invention).

[0037] The polymer of the present invention preferably has a polar functional group (sometimes referred to as "polar functional group (a)" for convenience) selected from functional group (a) in its molecular structure, preferably in a side chain, in terms of initial dispersibility and dispersion stability (collectively referred to as "dispersion characteristics"), handleability, and adhesion of solid particles. The polar functional group (a) of the polymer of the present invention is the same as the polar functional group (a) of the structural unit (C2) described below, and the preferred polar functional groups are also the same. The content (% by mass) and number of polar functional groups (a) of the polymer of the present invention are not particularly limited and are determined appropriately depending on the type and content of each structural unit, the weight-average molecular weight of the polymer of the present invention, etc.

[0038] (Structural Unit (A)) The structural unit (A) contained in the polymer of the present invention is a structural unit derived from a disubstituted vinyl monomer having a homopolymer glass transition temperature (Tg) of less than 50°C. The structural unit (A) contained in the polymer of the present invention may be one type or two or more types. The disubstituted vinyl monomer from which the structural unit (A) is derived has a glass transition temperature of less than 50°C when made into a homopolymer. This makes it possible to allow the polymer of the present invention to exhibit the desired function and to adjust the glass transition temperature of the polymer of the present invention to a suitable range described below. The glass transition temperature of the homopolymer of the disubstituted vinyl monomer is preferably less than 35°C, more preferably less than 20°C, and even more preferably less than 0°C. The glass transition point is a value measured using a homopolymer (dry sample) of the disubstituted vinyl monomer by the method described below.

[0039] The disubstituted vinyl monomer is not particularly limited as long as it is a monomer containing an ethylenically unsaturated bond having two substituents, and suitable compounds can be used. Examples of the disubstituted vinyl monomer include: disubstituted monomers of (meth)acrylic compounds (M1) such as (meth)acrylic acid compounds, (meth)acrylic acid ester compounds, (meth)acrylamide compounds, and (meth)acrylonitrile compounds; disubstituted monomers of vinyl compounds (M2) such as vinyl aromatic compounds (e.g., vinyl naphthalene compounds and vinyl carbazole compounds), allyl compounds, vinyl ester compounds, cyclic olefin compounds, diene compounds, and vinyl carboxylic acid ester compounds; itaconic acid dialkyl ester monomers; disubstituted monomers of maleimide compounds, N-vinyl-substituted imide compounds, and vinyl succinimide compounds; and disubstituted monomers obtained by introducing a substituent or a polar functional group (a) described below into each of the above compounds. Another aspect of the present invention is to include disubstituted monomers of styrene compounds and disubstituted monomers of vinyl ether compounds as long as the glass transition temperature of the homopolymer is less than 50°C. As the di-substituted vinyl monomer, a di-substituted monomer of a (meth)acrylic compound (M1) is preferred, a di-substituted monomer of a methacrylic compound is more preferred, a methacrylic acid ester monomer is further preferred, and a methacrylic acid alkyl ester monomer is particularly preferred.

[0040] Examples of (meth)acrylic acid ester compounds include (meth)acrylic acid alkyl ester compounds and (meth)acrylic acid aryl ester compounds, with (meth)acrylic acid alkyl ester compounds being preferred. The alkyl group constituting the (meth)acrylic acid alkyl ester compound may be any of a linear alkyl group, a branched alkyl group, and a cyclic alkyl group, with a linear alkyl group or a branched alkyl group being preferred. The number of carbon atoms in the alkyl group constituting the (meth)acrylic acid alkyl ester compound is not particularly limited and can be, for example, 1 to 24, but is preferably determined taking into consideration the glass transition temperature, the solubility of the polymer of the present invention in the dispersion medium, and the like. The number of carbon atoms in the alkyl group is, for example, preferably 3 to 24, more preferably 6 to 20, and even more preferably 8 to 18. Note that when the alkyl group is a cyclic alkyl group, the lower limit of the carbon number is preferably 6. The number of carbon atoms in the aryl group constituting the aryl ester is not particularly limited and can be, for example, 6 to 24, with 6 to 10 being preferred.

[0041] The monomer into which a substituent has been introduced into each of the above compounds is not particularly limited as long as it satisfies the above glass transition temperature. For example, a disubstituted monomer in which a group selected from the substituent Z described below (excluding the polar functional group (a) described below) has been introduced into a (meth)acrylic acid ester compound, preferably a (meth)acrylic acid alkyl ester compound, is mentioned. The (meth)acrylic acid ester compound into which a substituent is preferably introduced is as described above. However, the alkyl group constituting the (meth)acrylic acid alkyl ester compound is preferably a linear alkyl group, and the number of carbon atoms therein is not particularly limited, but can be, for example, 1 to 24, preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4. Examples of the substituent to be introduced include an alkoxy group, an aryloxy group, a heterocyclic group, an amino group, etc., with an aryloxy group, a heterocyclic group (particularly an epoxy group), and an amino group being preferred. The above-mentioned substituents are as described for the corresponding group of the substituent Z described below.

[0042] The monomer in which the polar functional group (a) is introduced into each of the above compounds is not particularly limited as long as it satisfies the above glass transition temperature. For example, a disubstituted monomer in which the polar functional group (a) is introduced into a (meth)acrylic acid ester compound, preferably a (meth)acrylic acid alkyl ester compound, is mentioned. The (meth)acrylic acid ester compound into which the polar functional group (a) is preferably introduced is as described above. However, the alkyl group constituting the alkyl ester compound is preferably a linear alkyl group. The number of carbon atoms therein is not particularly limited, but can be, for example, 1 to 24, preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4. Furthermore, as a monomer in which the polar functional group (a) is introduced into each of the above compounds, a suitable embodiment of the present invention also includes a monomer in which the polar functional group (a) is introduced into a (meth)acrylic acid (polyalkylene glycol) ester compound, which is an example of a (meth)acrylic acid ester compound. The alkylene glycol is not particularly limited, but is preferably an alkylene glycol having 1 to 4 carbon atoms. The degree of polymerization of the alkylene glycol is not particularly limited, and can be, for example, 2 to 10. The polar functional group (a) to be introduced is the same as the polar functional group (a) contained in the structural unit (C2) described below, and the preferred groups are also the same.

[0043] In terms of dispersion properties, handleability, and solid particle adhesion, the polymer of the present invention preferably has a structural unit (A) (for convenience, referred to as "structural unit (Aa)") derived from a disubstituted vinyl monomer into which a polar functional group (a) has been introduced. Note that, in the present invention, among structural units derived from a compound having a polar functional group (a), a structural unit derived from a compound whose homopolymer has a glass transition temperature of less than 50°C is considered to be a structural unit (A) (structural unit (Aa)) rather than a structural unit (C2) described below, even if it has a polar functional group (a).

[0044] Although the disubstituted vinyl monomer may contain a polymer chain in its structure, a preferred embodiment is a compound that does not contain a polymer chain. That is, a preferred embodiment is one in which both of the two substituents possessed by the disubstituted vinyl monomer are substituents that do not contain a polymer chain. The polymer chain is usually incorporated into the interior or end of the molecular chain that will become the side chain of the polymer of the present invention. Here, the molecular chain that will become the side chain of the polymer of the present invention refers to the molecular chain that constitutes the side chain of the polymer of the present invention in which the disubstituted vinyl monomer is incorporated, and is a molecular chain other than the molecular chain that constitutes the main chain of the polymer of the present invention, usually a molecular chain that is bonded to the molecular chain (atomic group) that constitutes the main chain. The polymer chain refers to a molecular chain in which two or more repeating units of one or more types are bonded, and specifically includes chains made of ordinary polymers, such as step-polymerized polymers or chain-polymerized polymers. Examples of step-polymerized polymers include polyurethane, polyurea, polyamide, polyimide, polyester, polyether, polycarbonate, polysiloxane, and copolymers thereof. Examples of chain-polymerized polymers include hydrocarbon polymers, vinyl polymers, (meth)acrylic polymers, and copolymers thereof. Among these, polymer chains that disubstituted vinyl monomers do not preferably have include polymer chains made of polyester, polymer chains made of polyether, polymer chains made of polysiloxane, and polymer chains made of (meth)acrylic polymer. Even if the partial structure connecting the molecular chains and polymer chains that constitute the main chain of the polymer of the present invention contains a polar functional group corresponding to the polar functional group (a), this polar functional group does not fully exhibit the function of adsorbing or adhering to solid particles, and therefore is not included in the structural unit (Aa).

[0045] Disubstituted vinyl monomers include 1,1-disubstituted vinyl monomers and 1,2-disubstituted vinyl monomers in terms of the positional relationship of the two substituents on the ethylenically unsaturated bond, but in the present invention, 1,1-disubstituted vinyl monomers are preferred. Suitable 1,1-disubstituted vinyl monomers are preferably disubstituted monomers of methacrylic compounds, more preferably methacrylic acid ester monomers, and even more preferably methacrylic acid alkyl ester monomers.

[0046] Specific examples of the disubstituted vinyl monomer include the monomers listed in Table 1 below.

[0047] (Structural Unit (B)) The structural unit (B) contained in the polymer of the present invention is at least one type of structural unit selected from structural units derived from styrene, structural units derived from vinyl ether, and structural units derived from (meth)acrylamide having a homopolymer glass transition temperature of 50°C or higher. In particular from the standpoints of dispersion properties, handleability, and solid particle adhesion, the structural unit (B) contained in the polymer of the present invention preferably contains a structural unit derived from (meth)acrylamide having a homopolymer glass transition temperature of 50°C or higher, and is more preferably a structural unit derived from such (meth)acrylamide. The structural unit (B) contained in the polymer of the present invention may be one type or two or more types.

[0048] The styrene (compound) from which the structural unit (B) is derived is not particularly limited, and examples thereof include unsubstituted styrene and substituted styrene compounds in which a substituent selected from the substituent Z described below (excluding the polar functional group (a) described below) is introduced into unsubstituted styrene. Examples of the substituent introduced into unsubstituted styrene include alkyl groups, aryl groups, amino groups, acyl groups, alkylthio groups, arylthio groups, alkylsulfonyl groups, arylsulfonyl groups, alkylsilyl groups, arylsilyl groups, alkoxysilyl groups, aryloxysilyl groups, and cyano groups. Each of the above substituents is as described for the corresponding group of the substituent Z described below.

[0049] The vinyl ether (compound) from which the structural unit (B) is derived is not particularly limited, and examples thereof include vinyl ether groups (CH ２═CH—O— group) to which a substituent selected from the substituent Z described below (excluding the polar functional group (a) described below) is bonded. Examples of the substituent bonded to the vinyl ether group include an alkyl group, an aralkyl group, an aryl group, a heterocyclic group, an amino group, an acyl group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, an alkylsilyl group, an arylsilyl group, an alkoxysilyl group, an aryloxysilyl group, and a cyano group, with an alkyl group being preferred. Each substituent bonded to the vinyl ether group is as described for the corresponding group of the substituent Z described below. However, the alkyl group may be any of a linear alkyl group, a branched alkyl group, and a cyclic alkyl group, but a linear alkyl group or a cyclic alkyl group is preferred. The number of carbon atoms in the alkyl is more preferably 1 to 12, and even more preferably 1 to 6. Note that when the alkyl group is a cyclic alkyl group, the lower limit of the carbon number is preferably 3.

[0050] The glass transition temperatures of the styrene and vinyl ether are not particularly limited, but preferably the glass transition temperature when made into a homopolymer is 50°C or higher. The glass transition temperatures of styrene and vinyl ether are more preferably within the range described below for the glass transition temperature of (meth)acrylamide. The glass transition point is a value measured by the method described below using a styrene homopolymer (dry sample) or a vinyl ether homopolymer (dry sample). Furthermore, although the styrene and vinyl ether are not particularly limited, one preferred embodiment is that they are not disubstituted, and in a more preferred embodiment they are monosubstituted.

[0051] The (meth)acrylamide (compound) from which the structural unit (B) is derived is a (meth)acrylamide having a homopolymer glass transition temperature of 50°C or higher. This allows the polymer of the present invention to exhibit the desired function, and also allows the glass transition temperature of the polymer of the present invention to be adjusted to a suitable range described below. The glass transition temperature of the (meth)acrylamide homopolymer is preferably 65°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. The glass transition point is a value measured using a (meth)acrylamide homopolymer (dry sample) by the method described below.

[0052] Examples of (meth)acrylamides include N-unsubstituted (meth)acrylamide compounds, N-monosubstituted (meth)acrylamide compounds, and N,N-disubstituted (meth)acrylamide compounds. The substituent substituting the nitrogen atom is not particularly limited, and examples include groups selected from the substituent Z described below (excluding the polar functional group (a) described below). Examples of the substituent include alkyl groups, aralkyl groups, aryl groups, heterocyclic groups, amino groups, acyl groups, alkylthio groups, arylthio groups, alkylsulfonyl groups, arylsulfonyl groups, alkylsilyl groups, arylsilyl groups, alkoxysilyl groups, aryloxysilyl groups, and cyano groups, with alkyl groups being preferred. Each of the above substituents is as described for the corresponding group of the substituent Z described below. The alkyl group may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, but a linear alkyl group or a branched alkyl group is preferred. The number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 12, and even more preferably 1 to 6. More specifically, preferred (meth)acrylamides include N-unsubstituted (meth)acrylamide compounds, N-alkyl(meth)acrylamide compounds, N,N-dialkyl(meth)acrylamide compounds, N-aryl(meth)acrylamide compounds, and N,N-diaryl(meth)acrylamide compounds. In N,N-disubstituted (meth)acrylamide compounds, two substituents may be bonded to each other to form a ring structure, and the ring structure may contain at least one heteroatom (e.g., a nitrogen atom, an oxygen atom, a sulfur atom, or a phosphorus atom) in addition to the nitrogen atom that forms the amide bond. An example of such an N,N-disubstituted (meth)acrylamide compound is (meth)acryloylmorpholine.

[0053] The styrene, vinyl ether, and (meth)acrylamide from which the structural unit (B) is derived each include compounds having a polar functional group (a) selected from the functional group group (a) described below introduced as a substituent. The styrene, vinyl ether, and (meth)acrylamide into which the polar functional group (a) is preferably introduced are as described above, and the polar functional group (a) is introduced into a substituent bonded to a benzene ring, a vinyl ether group, or a substituent substituting a nitrogen atom, respectively. The polar functional group (a) to be introduced is the same as the polar functional group (a) possessed by the structural unit (C2) described below, and the preferred groups are also the same. In terms of dispersion properties, handleability, and solid particle adhesion, the polymer of the present invention is one preferred embodiment having a structural unit (B) (conveniently referred to as "structural unit (Ba)") derived from at least one selected from styrene into which the polar functional group (a) has been introduced, vinyl ether into which the polar functional group (a) has been introduced, and (meth)acrylamide into which the polar functional group (a) has been introduced. In the present invention, among the structural units (B) derived from a compound having a polar functional group (a), structural units derived from styrene or vinyl ether and structural units derived from (meth)acrylamide whose homopolymer has a glass transition temperature of 50°C or higher are considered to be structural units (B) (structural units (Ba)) rather than structural units (C2) described below, even if they have a polar functional group (a).

[0054] Styrene, vinyl ether, and (meth)acrylamide may contain a polymer chain in their structure, but a compound that does not contain a polymer chain is one of the preferred embodiments. The polymer chain is usually incorporated into the interior or end of the molecular chain that becomes the side chain of the polymer of the present invention, as in the structural unit (A). The polymer chain is the same as the polymer chain described for the structural unit (A). Note that even if a polar functional group corresponding to the polar functional group (a) is contained in the partial structure that connects the molecular chain and the polymer chain that constitutes the main chain of the polymer of the present invention, this polar functional group does not sufficiently exhibit the function of adsorbing or adhering to solid particles, and therefore is not included in the structural unit (Ba).

[0055] Styrene, vinyl ether, and (meth)acrylamide may have a plurality of substituents bonded to the vinyl group, but one of the preferred embodiments is that they have one substituent (monosubstituted).

[0056] Specific examples of styrene, vinyl ether, and (meth)acrylamide include the respective monomers shown in Table 1 below.

[0057] (Structural Unit (C)) The polymer of the present invention may have, as an optional structural unit, one or more structural units (C) that do not correspond to either the structural unit (A) or the structural unit (B). The structural unit (C) is not particularly limited, but examples include the following. Structural unit (C1): a structural unit (C1A) derived from a vinyl monomer (excluding styrene, vinyl ether, and (meth)acrylamide) whose homopolymer has a glass transition temperature of 50°C or higher, and a structural unit (C1B) derived from a mono-substituted vinyl monomer whose homopolymer has a glass transition temperature of less than 50°C. Structural unit (C2): a structural unit having at least one polar functional group selected from the group of polar functional groups (a) described below.

[0058] - Structural Unit (C1) - A vinyl monomer which, when converted into a homopolymer, has a glass transition temperature of 50°C or higher, and which derives this structural unit (C1A), has a glass transition temperature of 50°C or higher, preferably 75°C or higher, more preferably 100°C or higher, and even more preferably 120°C or higher. The glass transition point is a value measured using a homopolymer (dry sample) of the vinyl monomer, using the method described below.

[0059] The vinyl monomer having a glass transition temperature of 50°C or higher when forming a homopolymer is not particularly limited as long as it is a monomer having an ethylenically unsaturated bond and is a monomer other than styrene, vinyl ether, and (meth)acrylamide that leads to the structural unit (B), and suitable compounds can be used. Examples of such vinyl monomers include (meth)acrylic compounds (M1C) such as (meth)acrylic acid ester compounds and (meth)acrylonitrile compounds; vinyl compounds (M2) such as vinyl aromatic compounds such as vinyl naphthalene compounds and vinyl carbazole compounds, allyl compounds, vinyl ester compounds, cyclic olefin compounds, diene compounds, and vinyl carboxylic acid ester compounds; itaconate dialkyl ester monomers; maleimide compounds, N-vinyl-substituted imide compounds, and vinyl succinimide compounds; and monomers in which a substituent has been introduced into any of the above compounds. As the vinyl monomer, (meth)acrylic compounds (M1C) are preferred, (meth)acrylic acid ester compounds are more preferred, and (meth)acrylic acid alkyl ester compounds are even more preferred.

[0060] Examples of (meth)acrylic acid ester compounds include (meth)acrylic acid alkyl ester compounds and (meth)acrylic acid aryl ester compounds, with (meth)acrylic acid alkyl ester compounds being preferred. The alkyl group constituting the (meth)acrylic acid alkyl ester compound may be any of a linear alkyl group, a branched alkyl group, and a cyclic alkyl group. The number of carbon atoms in the alkyl group constituting the (meth)acrylic acid alkyl ester compound is not particularly limited and can be, for example, 1 to 24. The alkyl group is preferably a short-chain alkyl group having 1 to 3 carbon atoms or a long-chain alkyl group having 4 to 20 carbon atoms. In terms of the solubility of the polymer of the present invention in a dispersion medium, the number of carbon atoms in the long-chain alkyl group is more preferably 6 to 20, and even more preferably 8 to 14. When the alkyl group is a cyclic alkyl group, the lower limit of the carbon number is preferably 6. The number of carbon atoms in the aryl group constituting the aryl ester is not particularly limited and can be, for example, 6 to 24, preferably 6 to 10, and more preferably 6.

[0061] The monomer into which a substituent has been introduced into each of the above compounds is not particularly limited as long as it satisfies the above glass transition temperature, and examples thereof include monomers into which a group selected from the substituent Z described below (excluding the polar functional group described below) has been introduced into a (meth)acrylic acid ester compound, preferably a (meth)acrylic acid alkyl ester compound. The (meth)acrylic acid ester compound into which a substituent is preferably introduced is as described above. Examples of the substituent to be introduced include a phenyl group, a heterocyclic group, an amino group, an acyl group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, an alkylsilyl group, an arylsilyl group, an alkoxysilyl group, an aryloxysilyl group, and a cyano group. Each of the above substituents is as described for the corresponding group of the substituent Z described below.

[0062] Vinyl monomers having a homopolymer glass transition temperature of 50°C or higher include mono-substituted vinyl monomers, di-substituted vinyl monomers, and tri- or higher-substituted vinyl monomers, with mono-substituted and di-substituted vinyl monomers being preferred. The di-substituted vinyl monomer may be a 1,2-disubstituted vinyl monomer, but is preferably a 1,1-disubstituted vinyl monomer. Preferred mono-substituted vinyl monomers are monomers of acrylic compounds, more preferably acrylate monomers, and even more preferably acrylate alkyl ester monomers. Preferred di-substituted vinyl monomers are di-substituted monomers of methacrylic compounds, more preferably methacrylate ester monomers, and even more preferably methacrylate alkyl ester monomers.

[0063] The mono-substituted vinyl monomer that derives the structural unit (C1B) and whose homopolymer has a glass transition temperature of less than 50°C is not particularly limited as long as it is a mono-substituted monomer having an ethylenically unsaturated bond and is a monomer other than styrene and vinyl ether that derives the structural unit (B), and suitable compounds can be used. Examples of such mono-substituted vinyl monomers include: mono-substituted monomers of the above-mentioned (meth)acrylic compound (M1); mono-substituted monomers of the above-mentioned vinyl compound (M2); N-vinyl-substituted imide compounds, vinyl succinimide compounds; and further, monomers in which a substituent has been introduced into each of the above compounds. As the mono-substituted vinyl monomer, a mono-substituted monomer of the (meth)acrylic compound (M1) is preferred, a mono-substituted monomer of an acrylic ester compound is more preferred, and a mono-substituted monomer of an acrylic acid alkyl ester compound is even more preferred.

[0064] The (meth)acrylic acid ester compound is the same as the (meth)acrylic acid ester compound described above for the vinyl monomer from which the structural unit (C1A) is derived, except that it is a monosubstituted compound.

[0065] The mono-substituted monomer obtained by introducing a substituent into each of the above compounds is not particularly limited, and examples thereof include a mono-substituted monomer of an acrylic ester compound, preferably a mono-substituted monomer of an acrylic acid alkyl ester compound, into which a group selected from the substituent Z described below (excluding the polar functional group described below) has been introduced. The acrylic ester compound into which a substituent is preferably introduced is as described above. The substituent to be introduced is the same as the substituent in the structural unit (C1A) above.

[0066] Specific examples of vinyl monomers from which the structural unit (C1) is derived include the monomers listed in Table 1 below.

[0067] - Structural Unit (C2) - The structural unit (C2) is a structural unit that has at least one polar functional group (a) selected from the following functional group group (a). In the structural unit (C2), the polar functional group (a) is preferably present in the molecular chain that will serve as a side chain of the polymer of the present invention, and more preferably is incorporated, for example, into the interior or terminal of the molecular chain that will serve as a side chain of the polymer of the present invention. In the present invention, the molecular chain that will serve as a side chain of the polymer of the present invention refers to the molecular chain that constitutes the side chain of the polymer of the present invention into which the structural unit (C2) has been incorporated, and is a molecular chain other than the molecular chain that constitutes the main chain of the polymer of the present invention, and typically a molecular chain that is bonded to the molecular chain (group of atoms) that constitutes the main chain.

[0068] The structural unit (C2) may have at least one polar functional group (a), and typically preferably has one to three polar functional groups. The number of polar functional groups (a) possessed by the polymer of the present invention is not particularly limited and is determined appropriately depending on the number of polar functional groups possessed by the structural unit (C2) itself, the content of the structural unit (C2), the molecular weight of the polymer of the present invention, and the like. The structural unit (C2) may have a polar functional group (a), and examples thereof include structural units derived from a polymerizable compound having at least one polar functional group selected from the functional group group (a). Examples of the polymerizable compound include compounds having a polymerizable group, a polar functional group (a) or a substituent having a polar functional group (a), and an appropriate linking group connecting the polymerizable group and the substituent, as well as polymerizable cyclic carboxylic acid anhydrides as described below. More specifically, such polymerizable compounds include compounds in which a carbon-carbon unsaturated bond as a polymerizable group is directly bonded to a polar functional group (a); compounds in which a carbon-carbon unsaturated bond and a polar functional group (a) are bonded via a linking group; and compounds in which the polar functional group (a) itself contains a carbon-carbon unsaturated bond (e.g., polymerizable cyclic carboxylic acid anhydrides, as described below). Compounds having a polar functional group (a) include compounds capable of introducing the polar functional group (a) into a polymer structural unit after polymerization through various reactions (e.g., alcohol, amino, mercapto, or epoxy compounds (including polymers) capable of undergoing addition reactions or condensation reactions with components derived from carboxylic acid anhydrides or structural units having a carbon-carbon unsaturated bond). The polymerizable group may be any group copolymerizable with the structural unit (C2), etc., and is preferably an ethylenically unsaturated group (carbon-carbon unsaturated bond). The substituent forming the substituent having a polar functional group is not particularly limited, and examples include groups selected from the substituent Z, as described below. The linking group is not particularly limited, but examples thereof include an alkylene group, an alkenylene group, an arylene, an oxygen atom, a sulfur atom, an imino group (—NR Ｎ -:R Ｎrepresents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. ), a carbonyl group, a phosphate linking group (-O-P(OH)(O)-O-), a phosphonate linking group (-P(OH)(O)-O-), or a group relating to a combination thereof. The linking group is preferably an alkylene group, an arylene group, a carbonyl group, an oxygen atom, a sulfur atom, or an imino group, or a group relating to a combination thereof, more preferably a group containing an alkylene group or an arylene group, and even more preferably a -CO-O-alkylene group. The number of atoms constituting the linking group is preferably 1 to 36, more preferably 1 to 24, and even more preferably 1 to 12. The number of linking atoms of the linking group is preferably 12 or less, more preferably 10 or less, and particularly preferably 8 or less. The lower limit is 1 or more. The number of linking atoms refers to the minimum number of atoms connecting the predetermined structural moieties. For example, -CO-O-CH ２ In the case of a - group, the number of atoms constituting the linking group is 6, but the number of linking atoms is 3.

[0069] <Functional Group (a)> Sulfonic acid group (sulfo group), phosphoric acid group (phosphoryl group), phosphonic acid group, hydroxy group, carboxy group, dicarboxylic acid group, thiol group (sulfanyl group), ether group, ester group, amide group, urethane group, urea group, imide group, fluoroalkyl group, and salts thereof

[0070] The sulfonic acid group, phosphoric acid group, phosphonic acid group, etc. included in the functional group group (a) are not particularly limited, but each has the same meaning as the corresponding group of the substituent Z described below. The dicarboxylic acid group is not particularly limited, but includes a group obtained by removing one or more hydrogen atoms from a dicarboxylic acid or its anhydride, and a structural unit itself formed by copolymerization of a polymerizable dicarboxylic acid or its anhydride as a polymerizable compound, and further includes a group obtained by reacting a dicarboxylic acid or its anhydride with an active hydrogen compound to cleave the anhydride group. As the group obtained by removing one or more hydrogen atoms from a dicarboxylic acid or its anhydride, a group obtained by removing one or more hydrogen atoms from an acyclic dicarboxylic acid or a cyclic dicarboxylic acid anhydride is preferred. Examples of dicarboxylic acid anhydrides include acyclic dicarboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and benzoic anhydride, and cyclic dicarboxylic acid anhydrides such as maleic anhydride, phthalic anhydride, fumaric anhydride, succinic anhydride, and itaconic anhydride. The polymerizable dicarboxylic acid or its anhydride is not particularly limited, but includes a dicarboxylic acid or its anhydride having an unsaturated bond in the molecule, preferably a polymerizable cyclic dicarboxylic acid anhydride. Examples of the polymerizable dicarboxylic acid include maleic acid and itaconic acid, and examples of the polymerizable cyclic dicarboxylic acid anhydride include maleic anhydride and itaconic acid anhydride. The active hydrogen compound is not particularly limited as long as it is a compound that reacts with a dicarboxylic acid anhydride group, and examples thereof include an alcohol compound, an amine compound, and a thiol compound.

[0071] Ether group (-O-), ester group (*-CO-O-**), amide group (*-CONR ＮＡ１ -**), urethane group (*-NR ＮＡ１ —CO—O—**), a urea group (—NR ＮＡ１ -CO-NR ＮＡ１ -), imide group (*-CO-NR ＮＡ２ -CO-**) each means the bond shown in the parentheses. Here, * and ** represent the bond, and R ＮＡ１ represents a hydrogen atom or a substituent, and R ＮＡ２ represents a bond, a hydrogen atom or a substituent. ＮＡ１ and R ＮＡ２The substituents that can be taken as R are not particularly limited, but examples thereof include groups selected from the substituent Z described below, and alkyl groups (including cycloalkyl groups), aryl groups, heterocyclic groups, etc. are preferred. The number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 12, and even more preferably 1 to 6. The number of carbon atoms in the aryl group is preferably 6 to 26, more preferably 6 to 20, and even more preferably 6 to 12. In addition, when two R ＮＡ１ may be the same or different. ＮＡ１ is preferably a hydrogen atom, and R ＮＡ２ is preferably a bonding moiety or a hydrogen atom. In each of the above groups, either of the two bonding moieties * and ** may be bonded to the main chain side of the polymer of the present invention, but it is preferable that the bonding moiety * is bonded to the main chain side of the polymer of the present invention.

[0072] The terminal group bonded to each of these groups is not particularly limited and represents a hydrogen atom or a substituent. Examples of the substituent that can be adopted as the terminal group include groups selected from the substituent Z described below. Among them, alkyl groups (including cycloalkyl groups), aryl groups, and heterocyclic groups are preferred, and alkyl groups or aryl groups are more preferred. In the present invention, the R ＮＡ１ When either the terminal group or the group has a hydrogen atom, this hydrogen atom is ＮＡ１ Interpret as follows.

[0073] The present invention includes an embodiment in which the ester group, ether group, and amide group are directly bonded to the polymer chain of the carbon-carbon double bond that forms the main chain of the polymer of the present invention when the structural unit (C2) is incorporated into the polymer of the present invention. In one embodiment of the present invention, the ester group, ether group, and amide group are preferably bonded via the linking group rather than directly to the partial structure that forms the main chain of the polymer of the present invention when the structural unit (C2) is incorporated into the polymer of the present invention.

[0074] Although ether groups are included in carboxy groups, hydroxy groups, dicarboxylic anhydride groups, ester groups, etc., the -O- groups contained in these groups are not considered to be ether groups. Furthermore, although ester groups are included in urethane groups, the -CO-O- groups contained therein are not considered to be ester groups. Furthermore, although amide groups are included in urethane groups, urea groups, imide groups, etc., the -CO-N groups contained therein are not considered to be ether groups. ＲＮ The - group is not interpreted as an amide group. The polar functional group may form a cyclic structure. For example, the imide group may form a cyclic imide group, specifically, a cyclic imide group derived from maleimide or phthalimide.

[0075] The fluoroalkyl group is a fluoroalkyl group in which at least one hydrogen atom in the alkyl group is substituted with a fluorine atom, and the molecular structure thereof may be linear, branched, or cyclic, with linear or branched being preferred. The number of carbon atoms in the fluoroalkyl group is not particularly limited, but is preferably 1 to 20, more preferably 1 to 12, still more preferably 2 to 8, and particularly preferably 2 to 7. In a preferred embodiment, the lower limit of the number of carbon atoms is 3 or more, and in the case where the fluoroalkyl group is linear, it is also preferred to set the lower limit to 4 or more. In the fluoroalkyl group, some or all of the hydrogen atoms may be substituted with fluorine atoms. In the present invention, a fluoroalkyl group in which some of the hydrogen atoms are substituted with fluorine atoms is preferred, and a methylene group (-CH) in which the carbon atom bonded to the main chain side of the polymer of the present invention is not substituted with a fluorine atom is preferred. ２ A fluoroalkyl group containing an ethylene group (—CH ) in which none of two or three consecutive carbon atoms, including the carbon atom bonded to the main chain side of the polymer of the present invention, is substituted with a fluorine atom is more preferred. ２ -CH ２ -) or propylene group (-CH ２ -CH ２ -CH ２-) is more preferred. In such a fluoroalkyl group in which some of the hydrogen atoms are substituted with fluorine atoms, the remaining alkyl group bonded to the carbon atom not substituted with fluorine atoms is preferably a perfluoroalkyl group in which all of the hydrogen atoms are substituted with fluorine atoms. The fluoroalkyl group may have a substituent other than a fluorine atom, and examples thereof include the substituent Z described below, and preferred examples include an alkyl group, an alkoxy group, an acyl group, an aryl group, an alkenyl group, a hydroxy group, a nitro group, a cyano group, a mercapto group, an amino group, an amide group, an acidic group (such as a carboxyl group, a phosphate group, or a sulfonic acid group), etc.

[0076] Groups capable of forming salts, such as sulfonic acid groups (sulfo groups), phosphate groups, phosphonic acid groups, hydroxy groups, carboxy groups, and dicarboxylic acid groups, may form salts with cations. Cations are not particularly limited and include various metal salts, ammonium or amine salts, etc. Amide groups, urethane groups, urea groups, imide groups, etc. may form salts with anions. Anions are not particularly limited and include anions of various inorganic or organic acids, etc.

[0077] The polar functional group possessed by the structural unit (C2) is preferably a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a hydroxy group, a carboxy group, a dicarboxylic acid group, an ether group, an amide group, or a salt thereof, and from the viewpoints of dispersion properties, resistance, and cycle properties, a carboxy group, a hydroxy group, a dicarboxylic acid group, etc. is more preferred.

[0078] The structural unit (C2) is not particularly limited, but is preferably a structural unit derived from the polymerizable compound described above, a structural unit derived from a compound obtained by introducing (substituting) the polar functional group into the polymerizable compound described above, or a structural unit derived from a maleimide compound, an N-vinyl-substituted imide compound, or a vinyl succinimide compound. A structural unit derived from a (meth)acrylic acid compound, a structural unit derived from a compound obtained by introducing the polar functional group into a (meth)acrylic acid ester compound, or a structural unit derived from a compound obtained by introducing the polar functional group into a (meth)acrylic acid alkyl ester is even more preferred. Examples of (meth)acrylic acid ester compounds into which a polar functional group has been introduced include (meth)acrylic acid alkyl ester compounds and (meth)acrylic acid aryl ester compounds, with (meth)acrylic acid alkyl ester compounds being preferred. The number of carbon atoms in the alkyl group constituting the (meth)acrylic acid alkyl ester compound is not particularly limited, but can be, for example, 1 to 24. The number of carbon atoms in the alkyl group is typically preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4. The number of carbon atoms in the aryl group that constitutes the aryl ester is not particularly limited, but can be, for example, 6 to 24, preferably 6 to 10, and more preferably 6. The structural unit (C2) is preferably a structural unit derived from a polymerizable compound in which at least one polar functional group selected from a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a hydroxy group, and a carboxy group has been introduced into the above-mentioned (meth)acrylic acid ester compound, preferably a (meth)acrylic acid alkyl ester compound, or a structural unit comprising a polymerizable dicarboxylic acid anhydride group (including a reaction product with an active hydrogen compound).

[0079] In the present invention, among the structural units contained in the structural unit (C), a structural unit that corresponds to both the structural unit (C1) and the structural unit (C2) is referred to as the structural unit (C2).

[0080] Specific examples of vinyl monomers from which the structural unit (C) is derived include the monomers shown in Table 1 below.

[0081] Specific examples of monomers or compounds from which each structural unit is derived are shown in Table 1 below, but the present invention is not limited to these. In Table 1, "Tg (°C)" indicates the glass transition temperature of the homopolymer of the monomer shown in the "Monomer Name" column, "Phosmer PP" indicates methacryloyloxypropylene glycol phosphate (molecular weight 460, manufactured by Unichemical Co., Ltd.), "p-" indicates "para-", and "t-" indicates "tert-".

[0082] In the polymer of the present invention, the combination of the structural unit (A) and the structural unit (B) is not particularly limited, and may be a combination of an appropriate structural unit (A) with an appropriate structural unit (B), and a combination of a preferred structural unit (A) with a preferred structural unit (B) is preferred. Specific examples of the polymer of the present invention include the polymers synthesized in the examples described below, but the present invention is not limited thereto.

[0083] The polymer of the present invention can be a commercially available product or a synthetic product. The polymer of the present invention can be synthesized by homopolymerizing or copolymerizing raw material compounds (monomers) using known methods. Specifically, the polymer can be synthesized by the method described in the Examples below. The method for incorporating the polar functional group (a) is not particularly limited, and examples thereof include a method of copolymerizing a monomer having the polar functional group (a), a method using a polymerization initiator or chain transfer agent that has (or generates) the polar functional group (a), a method utilizing a polymer reaction, an ene reaction to a double bond, an ene-thiol reaction, or an ATRP (atom transfer radical polymerization) polymerization method using a copper catalyst. Alternatively, the polar functional group (a) can be introduced by using a functional group present in the main chain, side chain, or terminal of the polymer of the present invention as a reaction site. For example, the polar functional group (a) can be introduced by various reactions with a dicarboxylic acid anhydride group in the polymer chain using a compound having a functional group.

[0084] The structural units (A) to (C) may each have a substituent (excluding the polar functional group (a)). The substituent that each structural unit may have is not particularly limited, but examples thereof include groups selected from the following substituent Z.

[0085] - Substituent Z - An 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.), an 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, butadiynyl, phenylethynyl, etc.), a cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, for example, cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), In the present invention, alkyl groups usually include cycloalkyl groups, but will be described separately here.), aryl groups (preferably aryl groups having 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl groups (preferably aralkyl groups having 7 to 23 carbon atoms, for example, benzyl, phenethyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, more preferably 5- or 6-membered heterocyclic groups having at least one oxygen atom, sulfur atom, or nitrogen atom. Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups.For example, a tetrahydropyran ring group, a tetrahydrofuran ring group, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, a pyrrolidone group, etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), an aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms, for example, phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), a heterocyclic oxy group (a group in which an -O- group is bonded to the above heterocyclic group), an alkoxycarbonyl group (preferably or an alkoxycarbonyl group having 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, etc.), an aryloxycarbonyl group (preferably an aryloxycarbonyl group having 7 to 26 carbon atoms, for example, phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), a heterocyclic oxycarbonyl group (a group in which an —O—CO— group is bonded to the above heterocyclic group), an amino group (preferably an amino group having 0 to 20 carbon atoms, an alkylamino group, or an arylamino group, for example, amino(—NH ２), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl group (preferably a sulfamoyl group having 0 to 20 carbon atoms, for example, N,N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyl group (including an alkylcarbonyl group, an alkenylcarbonyl group, an alkynylcarbonyl group, an arylcarbonyl group, or a heterocyclic carbonyl group, preferably an acyl group having 1 to 20 carbon atoms, for example, acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotinoyl, etc.), acyl Oxy groups (including alkylcarbonyloxy groups, alkenylcarbonyloxy groups, alkynylcarbonyloxy groups, and heterocyclic carbonyloxy groups, preferably acyloxy groups having 1 to 20 carbon atoms, for example, acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyloxy, acryloyloxy, methacryloyloxy, crotonoyloxy, and nicotinoyloxy), aryloyloxy groups (preferably aryloyloxy groups having 7 to 23 carbon atoms, for example, benzoyloxy and naphthoyloxy), carbamoyl groups (preferably carbamoyl groups having 1 to 20 carbon atoms, for example, N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), acylamino groups (preferably acylamino groups having 1 to 20 carbon atoms, for example, acetylamino, benzoylamino, etc.), alkylthio groups (preferably alkylthio groups having 1 to 20 carbon atoms, for example, methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio groups (preferably arylthio groups having 6 to 26 carbon atoms, for example, phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), heterocyclic thio groups (groups in which an -S- group is bonded to the above heterocyclic group), alkylsulfonyl groups (preferably alkylsulfonyl groups having 1 to 20 carbon atoms, for example, methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl groups (preferably an arylsulfonyl group having 6 to 22 carbon atoms, for example, benzenesulfonyl; an alkylsilyl group (preferably an alkylsilyl group having 1 to 20 carbon atoms, for example, monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl; an arylsilyl group (preferably an arylsilyl group having 6 to 42 carbon atoms, for example, triphenylsilyl; an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 20 carbon atoms, for example, monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl; an aryloxysilyl group having 6 to 42 carbon atoms, for example, triphenyloxysilyl; an aryloxysilyl group having 6 to 42 carbon atoms, for example, triphenyloxysilyl; a phosphoryl group (preferably a phosphoric acid group having 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 phosphonic acid group (preferably a phosphonic acid group having 0 to 20 carbon atoms, for example, —PO(OR Ｐ ) ２ ), sulfo group (sulfonic acid group), carboxy group, hydroxy group, sulfanyl group, cyano group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). Ｐis a hydrogen atom or a substituent (preferably a group selected from the substituent Z). Each of the groups listed as the substituent Z may be further substituted with the substituent Z. The alkyl group, alkylene group, alkenyl group, alkenylene group, alkynyl group and / or alkynylene group may be cyclic or chain-like, and may be linear or branched.

[0086] In the polymer of the present invention, the total content of the structural units (A) and (B) in the polymer of the present invention is 80% by mass or more. When this total content in the polymer of the present invention is 80% by mass or more, the inorganic solid electrolyte-containing composition of the present invention has excellent dispersion stability and handleability, and the solid particles can be firmly adhered, resulting in an all-solid-state secondary battery with low resistance and excellent high-voltage cycle characteristics. In terms of dispersion stability, handleability, solid particle adhesion, and further resistance and high-voltage cycle characteristics, this total content in the polymer of the present invention is preferably 90% by mass or more, more preferably 95% by mass or more. On the other hand, the upper limit of this total content in the polymer of the present invention can be 100% by mass, but is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 96% by mass or less.

[0087] In the polymer of the present invention, the content of the structural unit (A) and the content of the structural unit (B) in the polymer of the present invention can each be appropriately determined taking into consideration the above-mentioned total content. The content of the structural unit (A) in the polymer of the present invention is preferably 10 to 95% by mass, more preferably 30 to 90% by mass, and even more preferably 50 to 80% by mass, from the viewpoints of, for example, dispersion stability, handleability, adhesion of solid particles, and further resistance and high-voltage cycle characteristics. When the structural unit (A) includes a structural unit (Aa) having the polar functional group (a), the content of the structural unit (Aa) in the polymer of the present invention is not particularly limited and can be appropriately determined. For example, from the viewpoints of dispersion stability, handleability, adhesion of solid particles, and further resistance and high-voltage cycle characteristics, it is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and even more preferably 3 to 20% by mass. Furthermore, the content of the structural unit (Aa) in the structural unit (A) is not particularly limited and can be determined as appropriate. For example, when the total mass of the structural unit (A) is taken as 100 mass%, the content of the structural unit (Aa) is preferably 1 to 100 mass%, more preferably 3 to 60 mass%, and even more preferably 5 to 40 mass%, in terms of dispersion stability, handleability, adhesion of solid particles, and further resistance and high-voltage cycle characteristics.

[0088] The content of the structural unit (B) in the polymer of the present invention is preferably 1 to 50% by mass, more preferably 2 to 40% by mass, and even more preferably 3 to 25% by mass, from the viewpoints of, for example, dispersion stability, handleability, adhesion of solid particles, and further resistance and high-voltage cycle characteristics. When the structural unit (B) contains a structural unit (Ba) having the polar functional group (a), the content of the structural unit (Ba) in the polymer of the present invention is not particularly limited and can be determined as appropriate. For example, from the viewpoints of dispersion stability, handleability, adhesion of solid particles, and further resistance and high-voltage cycle characteristics, it is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and even more preferably 3 to 20% by mass. Furthermore, the content of the structural unit (Ba) in the structural unit (B) is not particularly limited and can be determined as appropriate. For example, when the total mass of the structural unit (B) is taken as 100 mass%, the content of the structural unit (Ba) is preferably from 5 to 100 mass%, more preferably from 10 to 60 mass%, and even more preferably from 20 to 40 mass%, in terms of dispersion stability, handleability, adhesion of solid particles, and further resistance and high-voltage cycle characteristics.

[0089] In the present invention, the mass ratio of the content of the structural unit (A) to the content of the structural unit (B) [(content of the structural unit (A)) / (content of the structural unit (B)]] can be determined appropriately. For example, from the viewpoints of dispersion stability, handleability, adhesion of solid particles, and further resistance and high-voltage cycle characteristics, the mass ratio [(content of the structural unit (A)) / (content of the structural unit (B)]] is preferably 1 to 50, more preferably 2 to 20, and even more preferably 3 to 10.

[0090] In the polymer of the present invention, the content of the structural unit (C) in the polymer of the present invention is appropriately determined taking into consideration the total content of the structural unit (A) and the structural unit (B), and is, for example, preferably 0 to 50% by mass, more preferably 2 to 30% by mass, and even more preferably 3 to 15% by mass. In the polymer of the present invention, the content of the structural unit (C1) in the polymer of the present invention is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and even more preferably 0 to 10% by mass, from the viewpoint of increasing the solubility in the dispersion medium and further improving the dispersion properties and handleability. In the polymer of the present invention, the content of the structural unit (C2) in the polymer of the present invention is preferably 0 to 50% by mass, more preferably 2 to 30% by mass, and even more preferably 3 to 15% by mass, from the viewpoint of particularly improving the dispersion properties and adhesion of solid particles.

[0091] When the polymer of the present invention has a plurality of structural units corresponding to the structural unit, the content of each structural unit mentioned above refers to the total content of the plurality of structural units.

[0092] The polymer of the present invention may contain the structural unit (A) and the structural unit (B), but is typically preferably a polymer having a polymer chain of a carbon-carbon double bond in its main chain. In the present invention, the polymer chain of a carbon-carbon double bond refers to a polymer chain formed by polymerization of a carbon-carbon double bond (ethylenically unsaturated group), and specifically refers to a polymer chain formed by polymerization (homopolymerization or copolymerization) of a monomer having a carbon-carbon unsaturated bond. Examples of polymers having a polymer chain of a carbon-carbon double bond in their main chain include chain-polymerized polymers such as fluoropolymers (fluorine-containing polymers), hydrocarbon polymers, vinyl polymers, and (meth)acrylic polymers. Here, the term "(meth)acrylic polymer" refers to, for example, a polymer made of a (co)polymer containing 50% by mass or more of structural units derived from a (meth)acrylic compound (M1), and the term "vinyl polymer" refers to, for example, a copolymer containing 50% by mass or more of structural units derived from a vinyl-based compound (M2) (provided that the content of structural units derived from the (meth)acrylic compound (M1) is less than 50% by mass). The polymer of the present invention is preferably a vinyl polymer or a (meth)acrylic polymer, more preferably a (meth)acrylic polymer.

[0093] The molecular structure of the polymer of the present invention is not particularly limited as long as it contains the above-mentioned structural units (A) and (B), and can have various molecular structures such as a linear polymer (straight-chain polymer), a graft polymer, a dendrimer, a star polymer, or a core-shell polymer. The polymer of the present invention is preferably not a multi-branched polymer such as a dendrimer or a star polymer, or a core-shell polymer. Specifically, a linear polymer or a graft polymer is preferred, with a linear polymer being more preferred. In the present invention, a linear polymer includes not only a polymer having no completely branched structure, but also a substantially linear polymer having a short molecular chain (non-polymerizable molecular structure) in addition to the main chain. A graft polymer refers to a polymer having a polymerizable graft chain as a side chain.

[0094] (Physical properties or characteristics of the polymer or polymer binder of the present invention) The polymer binder (polymer of the present invention) exhibits the property of dissolving in the dispersion medium contained in the inorganic solid electrolyte-containing composition (solubility, solubility). That is, the polymer binder in the inorganic solid electrolyte-containing composition exists in a state dissolved in the dispersion medium in the inorganic solid electrolyte-containing composition, depending on its content. When the polymer binder is dissolved in the dispersion medium, it stably exhibits the function of dispersing solid particles in the dispersion medium, thereby improving the dispersion state of the solid particles in the inorganic solid electrolyte-containing composition. In the present invention, the polymer binder being dissolved in the dispersion medium is not limited to an embodiment in which all of the polymer binder is dissolved in the dispersion medium. For example, as long as the solubility in the dispersion medium is 50% or more, a portion of the polymer binder may be insoluble in the inorganic solid electrolyte-containing composition. Note that when the polymer binder contains components other than the polymer of the present invention, it is sufficient that at least the polymer of the present invention satisfies the above solubility. The solubility is measured as follows. That is, approximately 0.1 g of the binder constituent component (solid) was precisely weighed, and the weighed mass was designated as W0. Next, the binder constituent component and 10 g of the dispersion medium were placed in a container and mixed for 48 hours at 25°C and 100 rpm using a mix rotor (model number VMR-5, manufactured by AS ONE Corporation). Thereafter, the insoluble matter was filtered from the solution, and the obtained solid was vacuum-dried at 120°C for 3 hours, and the mass W1 of the insoluble matter was precisely weighed. Then, the solubility (%) in the dispersion medium was calculated according to the following formula: Solubility (%) = (W0 - W1) / W0 × 100

[0095] In the present invention, the solubility of the polymer binder in the dispersion medium can be appropriately imparted by the structure, composition (type and content of structural units), weight average molecular weight, and further combination with the dispersion medium of the polymer of the present invention.

[0096] The polymer or polymer binder of the present invention preferably has the following physical properties or characteristics. The glass transition temperature (Tg) of the polymer of the present invention is not particularly limited, but in terms of resistance and high-voltage cycle characteristics, it is preferably −60° C. or higher, more preferably −20° C. or higher, even more preferably −10° C. or higher, particularly preferably −5° C. or higher, and most preferably 0° C. or higher. The upper limit of the glass transition temperature is not particularly limited, but is preferably 55° C. or lower, more preferably 25° C. or lower. When the glass transition temperature of the polymer of the present invention is −60° C. or higher, particularly −20° C. or higher, the strength of the polymer itself is increased, which can strengthen the adhesion of solid particles. It is also thought that the polymer itself is less likely to deteriorate even when the all-solid-state secondary battery is charged at a high potential, and as a result, the resistance and high-voltage cycle characteristics of the all-solid-state secondary battery can be further improved.

[0097] - Measurement of Glass Transition Temperature - The glass transition temperature (Tg) of a polymer is measured under the following conditions using a dried sample of the polymer and a differential scanning calorimeter (DSC7000, manufactured by Hitachi High-Tech Science Corporation). The measurement is performed twice using the same sample, and the result of the second measurement is used. - Atmosphere in the measurement chamber: Nitrogen (50 mL / min) - Heating rate: 5°C / min - Measurement start temperature: -100°C - Measurement end temperature: 350°C - Sample pan: Aluminum pan - Mass of measurement sample: 5 mg - Calculation of Tg: Tg is calculated by rounding off the decimal point of the midpoint between the start and end points of the decline on the DSC chart.

[0098] The weight average molecular weight of the polymer of the present invention is not particularly limited. For example, ３ More than 3.0 × 10 ４ More preferably, 1.0 × 10 ５ More preferably, 2.0 × 10 ５ The upper limit is 5.0 × 10 ６ The following is practically true: 2.0 x 10 ６ Preferably, the value is 1.0 x 10 or less. ６ More preferably, 6.0 x 10 ５The following is more preferred: The weight average molecular weight of the polymer of the present invention can be appropriately adjusted by changing the type and content of the polymerization initiator, etc., the polymerization time, the polymerization temperature, etc.

[0099] - Molecular Weight Measurement - In the present invention, unless otherwise specified, the molecular weight of a polymer or polymer chain refers to a weight-average molecular weight or number-average molecular weight measured by gel permeation chromatography (GPC) in terms of standard polystyrene. The measurement method can be basically the method under Condition 1 or Condition 2 below, with Condition 2 being preferred. However, depending on the type of polymer or polymer chain, an appropriate eluent may be selected and used. (Condition 1) Column: Two TOSOH TSKgel Super AWM-H (trade name, manufactured by Tosoh Corporation) connected together Carrier: 10 mM LiBr / N-methylpyrrolidone Measurement temperature: 40°C Carrier flow rate: 1.0 ml / min Sample concentration: 0.1 mass% Detector: RI (refractive index) detector (Condition 2) Column: A column connected together 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 mass% Detector: RI (refractive index) detector

[0100] The polymer of the present invention may be a non-crosslinked polymer or a crosslinked polymer. Furthermore, when crosslinking of the polymer of the present invention progresses due to heating or application of voltage, the molecular weight may be larger than the above-mentioned molecular weight. Preferably, the polymer of the present invention has a weight-average molecular weight within the above-mentioned range at the start of use of the all-solid-state secondary battery.

[0101] The polymer of the present invention is preferably amorphous. In the present invention, a polymer being "amorphous" typically means that no endothermic peak due to crystalline melting is observed when measuring the glass transition temperature. The water concentration of the polymer binder (polymer of the present invention) is preferably 100 ppm (by mass) or less. The polymer binder (polymer of the present invention) may be crystallized and dried, or the dispersion may be used as is.

[0102] <Other Polymers> The polymer binder may contain one or more other polymers to reinforce the function of the polymer of the present invention. As such other polymers, those that function as binders commonly used in all-solid-state secondary batteries can be appropriately selected and used. The content of the other polymers in the polymer binder is not particularly limited, but is preferably, for example, 0.01 to 4 mass% relative to 100 mass% of the polymer binder.

[0103] The content of the polymer binder in the inorganic solid electrolyte-containing composition is not particularly limited, but is preferably 0.1 to 5.0% by mass, more preferably 0.2 to 4.0% by mass, and even more preferably 0.3 to 2.0% by mass, particularly in terms of dispersion stability, handleability, adhesion of solid particles, and further resistance and high-voltage cycle characteristics. Furthermore, for the same reasons, the content of the polymer binder in 100% by mass of the solid content of the inorganic solid electrolyte-containing composition (solid content equivalent) is preferably 0.1 to 6.0% by mass, more preferably 0.3 to 5.0% by mass, and even more preferably 0.4 to 2.5% by mass. In the present invention, the mass ratio of the total mass (total amount) of the inorganic solid electrolyte and the active material to the mass of the polymer binder in 100% by mass of the solid content [(mass of inorganic solid electrolyte + mass of active material) / (total mass of polymer binder)] is preferably in the range of 1000 to 1. This ratio is more preferably 500 to 2, and even more preferably 100 to 10.

[0104] [Dispersion Medium] The inorganic solid electrolyte-containing composition of the present invention contains a dispersion medium that disperses or dissolves the above-mentioned components. Such a dispersion medium may be any organic compound that is liquid in the usage environment, and examples thereof include various organic solvents, specifically alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, nitrile compounds, ester compounds, etc. The dispersion medium may be a non-polar dispersion medium (hydrophobic dispersion medium) or a polar dispersion medium (hydrophilic dispersion medium), but a non-polar dispersion medium is preferred in terms of its excellent dispersibility. A non-polar dispersion medium generally refers to a dispersion medium that has low affinity for water. In the present invention, examples thereof include ester compounds, ketone compounds, ether compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, etc.

[0105] Examples of alcohol compounds include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, 2-methyl-2,4-pentanediol, 1,3-butanediol, and 1,4-butanediol.

[0106] Examples of the ether compound include alkylene glycols (diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, etc.), alkylene glycol monoalkyl ethers (ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, etc.), alkylene glycol dialkyl ethers (ethylene glycol dimethyl ether, etc.), dialkyl ethers (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), and cyclic ethers (tetrahydrofuran, dioxane (including 1,2-, 1,3-, and 1,4-isomers), etc.).

[0107] 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, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropanamide, and hexamethylphosphoric triamide.

[0108] Examples of amine compounds include triethylamine, diisopropylethylamine, and tributylamine. Examples of ketone compounds include acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone, cyclohexanone, cycloheptanone, dipropyl ketone, dibutyl ketone, diisopropyl ketone, diisobutyl ketone (DIBK), isobutyl propyl ketone, sec-butyl propyl ketone, pentyl propyl ketone, and butyl propyl ketone. Examples of aromatic hydrocarbon compounds include benzene, toluene, xylene, and perfluorotoluene. Examples of aliphatic hydrocarbon compounds include hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane, decalin, paraffin, gasoline, naphtha, kerosene, and diesel. Examples of nitrile compounds include acetonitrile, propionitrile, and isobutyronitrile. Examples of the ester compound include ethyl acetate, propyl acetate, butyl acetate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, butyl pentanoate, pentyl pentanoate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, isobutyl isobutyrate, propyl pivalate, isopropyl pivalate, butyl pivalate, and isobutyl pivalate.

[0109] In the present invention, among these, ether compounds, ketone compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, and ester compounds are preferred, and ester compounds, ketone compounds, aromatic hydrocarbon compounds, and ether compounds are more preferred.

[0110] The number of carbon atoms in the compound constituting the dispersion medium is not particularly limited, and is preferably 2 to 30, more preferably 4 to 20, even more preferably 6 to 15, and particularly preferably 7 to 12.

[0111] The boiling point of the dispersion medium at normal pressure (1 atmosphere: 101,325 Pa) is preferably 50° C. or higher, more preferably 70° C. or higher. The upper limit is preferably 250° C. or lower, more preferably 220° C. or lower.

[0112] The inorganic solid electrolyte-containing composition may contain one or more dispersion media. Examples of dispersion media containing two or more dispersion media include xylene (a mixture of xylene isomers in which the molar ratio of the isomers is ortho-isomer:para-isomer:meta-isomer = 1:5:2), mixed xylenes (a mixture of o-xylene, p-xylene, m-xylene, and ethylbenzene), etc. The content of the dispersion media in the inorganic solid electrolyte-containing composition is not particularly limited and is set within a range that satisfies the above solid content concentration.

[0113] [Active Material] The inorganic solid electrolyte-containing composition of the present invention preferably contains an active material capable of inserting and releasing ions of a metal belonging to Group 1 or Group 2 of the periodic table. Examples of the active material include a positive electrode active material and a negative electrode active material, as described below. In the present invention, an inorganic solid electrolyte-containing composition containing an active material (positive electrode active material or negative electrode active material) may be referred to as an electrode composition (positive electrode composition or negative electrode composition).

[0114] <Positive Electrode Active Material> The positive electrode active material is an active material capable of inserting and releasing ions of a metal belonging to Group 1 or Group 2 of the periodic table, and is preferably one that can insert and release lithium ions reversibly. The material is not particularly limited as long as it has the above-mentioned properties, and may be a transition metal oxide, or an element that can be composited with Li, such as an organic substance or sulfur. Among these, it is preferable to use a transition metal oxide as the positive electrode active material, and the transition metal element M ａ A transition metal oxide containing one or more elements selected from Co, Ni, Fe, Mn, Cu, and V is more preferred. ｂ(Elements of Group 1 (Ia) of the periodic table other than lithium, elements of Group 2 (IIa), Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, etc.) may be mixed. ａ The amount of Li / M is preferably 0 to 30 mol % relative to the amount of Li / M (100 mol %). ａ More preferably, the transition metal oxides are synthesized by mixing them so that the molar ratio of the above is 0.3 to 2.2. Specific examples of the transition metal oxide include (MA) a transition metal oxide having a layered rock salt structure, (MB) a transition metal oxide having a spinel structure, (MC) a lithium-containing transition metal phosphate compound, (MD) a lithium-containing transition metal halide phosphate compound, and (ME) a ​​lithium-containing transition metal silicate compound.

[0115] (MA) Specific examples of transition metal oxides 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 cobalt lithium aluminum oxide [NCA]), LiNi １／３ Co １／３ Mn １／３ O ２ (Lithium nickel manganese cobalt oxide [NMC]) and LiNi ０．５ Mn ０．５ O ２ (Lithium manganese nickel oxide). (MB) Specific examples of transition metal oxides having a spinel structure include 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 ８Examples of the (MC) lithium-containing transition metal phosphate compound include LiFePO ４ and Li ３ Fe ２ (P.O. ４ ) ３ Olivine-type iron phosphate salts such as LiFeP ２ O ７ Iron pyrophosphates such as LiCoPO ４ Cobalt phosphates such as Li ３ V ２ (P.O. ４ ) ３ (MD) Examples of lithium-containing transition metal halide phosphate compounds include, for example, Li ２ FePO ４ Fluorophosphate iron salts such as F, Li ２ MnPO ４ Fluorophosphate manganese salts such as F and Li ２ CoPO ４ Examples of the (ME) lithium-containing transition metal silicate compound include cobalt fluoride phosphates such as Li ２ FeSiO ４ , Li ２ MnSiO ４ , Li ２ CoSiO ４ In the present invention, transition metal oxides having a layered rock salt structure (MA) are preferred, and LCO or NMC are more preferred.

[0116] The shape of the positive electrode active material is not particularly limited, but it is preferably particulate in the inorganic solid electrolyte-containing composition. When the positive electrode active material is particulate, the particle size (volume average particle size) of the positive electrode active material is not particularly limited. For example, it can be 0.1 to 50 μm. The particle size of the positive electrode active material particles can be prepared in the same manner as the particle size of the inorganic solid electrolyte, and the measurement method is the same as the measurement method for the particle size of the inorganic solid electrolyte. The positive electrode active material obtained by the calcination method may be used after washing with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0117] The inorganic solid electrolyte-containing composition may contain one or more positive electrode active materials. The content of the positive electrode active materials in the inorganic solid electrolyte-containing composition is not particularly limited, and is preferably 10 to 97 mass %, more preferably 30 to 95 mass %, even more preferably 40 to 93 mass %, and particularly preferably 50 to 90 mass %, based on 100 mass % of the solid content.

[0118] <Negative Electrode Active Material> The negative electrode active material is an active material capable of inserting and releasing ions of a metal belonging to Group 1 or 2 of the periodic table, and is preferably one that can reversibly insert and release lithium ions. The material is not particularly limited as long as it has the above-mentioned properties, and examples thereof include carbonaceous materials, metal oxides, metal composite oxides, lithium alone, lithium alloys, and negative electrode active materials that can form an alloy (can be alloyed) with lithium. Among these, carbonaceous materials, metal composite oxides, and lithium alone are preferably used from the viewpoint of reliability. Active materials that can be alloyed with lithium are preferred in terms of enabling the capacity of all-solid-state secondary batteries to be increased.

[0119] The carbonaceous material used as the negative electrode active material is a material essentially composed of carbon. Examples include carbon black such as petroleum pitch and acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor-grown graphite, etc.), and carbonaceous materials obtained by calcining various synthetic resins such as PAN (polyacrylonitrile)-based resins or furfuryl alcohol resins. Further examples include various carbon fibers such as PAN-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polyvinyl alcohol)-based carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers, as well as mesophase microspheres, graphite whiskers, and flat graphite. These carbonaceous materials can also be divided into difficult-to-graphitize carbonaceous materials (also called hard carbon) and graphite-based carbonaceous materials depending on the degree of graphitization. Furthermore, the carbonaceous material preferably has the interplanar spacing or density and crystallite size described in JP-A-62-22066, JP-A-2-6856, and JP-A-3-45473. The carbonaceous material does not need to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, etc. can also be used. As the carbonaceous material, hard carbon or graphite is preferably used, and graphite is more preferably used.

[0120] The oxide of a metal or metalloid element used as the negative electrode active material is not particularly limited as long as it is an oxide capable of absorbing and releasing lithium, and examples thereof include oxides of metal elements (metal oxides), composite oxides of metal elements, or composite oxides of metal elements and metalloid elements (collectively referred to as metal composite oxides), and oxides of metalloid elements (metalloid oxides). Among these oxides, amorphous oxides are preferred, and chalcogenides, which are reaction products of metal elements and elements of Group 16 of the periodic table, are also preferred. In the present invention, the term "metalloid element" refers to an element that exhibits properties intermediate between metal elements and non-metalloid elements, and typically includes six elements: boron, silicon, germanium, arsenic, antimony, and tellurium, and three elements: selenium, polonium, and astatine. Furthermore, "amorphous" refers to an oxide having a broad scattering band with a peak in the 2θ range of 20° to 40° in an X-ray diffraction method using CuKα radiation, and may also have crystalline diffraction lines. The strongest intensity of the crystalline diffraction lines observed at 2θ values ​​of 40° to 70° is preferably 100 times or less, more preferably 5 times or less, the diffraction line intensity at the apex of a broad scattering band observed at 2θ values ​​of 20° to 40°, and it is particularly preferable that the crystal has no crystalline diffraction lines.

[0121] Among the compound group consisting of the amorphous oxides and chalcogenides, amorphous oxides or chalcogenides of metalloid elements are more preferred, and (composite) oxides or chalcogenides consisting of one element selected from Groups 13 (IIIB) to 15 (VB) of the periodic table (e.g., Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) alone or in combination of two or more elements thereof are particularly preferred. Specific examples of preferred 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 ８Bi 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 Suitable examples of negative electrode active materials that can be used in combination with amorphous oxides mainly containing Sn, Si, or Ge include carbonaceous materials that can occlude and / or release lithium ions or lithium metal, lithium alone, lithium alloys, and negative electrode active materials that can be alloyed with lithium.

[0122] From the viewpoint of charge-discharge characteristics, it is preferable that the oxides of metal or semimetal elements, particularly the metal (composite) oxides and the chalcogenides contain at least one of titanium and lithium as a constituent unit. Examples of the lithium-containing metal composite oxide (lithium composite metal oxide) include composite oxides of lithium oxide and the metal (composite) oxides or the chalcogenides, more specifically, Li ２ SnO ２ The negative electrode active material, for example, a metal oxide, preferably contains titanium element (titanium oxide). Specifically, Li ４ Ti ５ O １２ Lithium titanate (LTO) is preferred because it has small volume fluctuations during absorption and desorption of lithium ions, has excellent rapid charge and discharge characteristics, suppresses electrode deterioration, and can improve the life of the lithium ion secondary battery.

[0123] The lithium alloy used as the negative electrode active material is not particularly limited as long as it is an alloy that is commonly used as a negative electrode active material for secondary batteries, and examples thereof include lithium-aluminum alloys, specifically lithium-aluminum alloys having lithium as the base metal and 10 mass % of aluminum added thereto.

[0124] The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is one commonly used as a negative electrode active material for secondary batteries. Such active materials undergo large expansion and contraction during charging and discharging of all-solid-state secondary batteries, accelerating the deterioration of cycle characteristics. However, the inorganic solid electrolyte-containing composition of the present invention contains the above-mentioned polymer binder, thereby suppressing the deterioration of cycle characteristics (including high-voltage cycle characteristics). Examples of such active materials include (negative electrode) active materials (alloys, etc.) containing silicon or tin, and metals such as Al and In. Negative electrode active materials containing silicon (silicon-containing active materials) that enable higher battery capacity are preferred, and silicon-containing active materials with a silicon content of 50 mol% or more of the total constituent elements are more preferred. Generally, negative electrodes containing these negative electrode active materials (e.g., Si negative electrodes containing silicon-containing active materials, Sn negative electrodes containing tin-containing active materials, etc.) can absorb more Li ions than carbon negative electrodes (e.g., graphite and acetylene black). That is, the amount of Li ions absorbed per unit mass is increased. Therefore, the battery capacity (energy density) can be increased, which has the advantage of extending the battery operating time. Examples of silicon-containing active materials include Si, SiO ｘ Silicon materials such as silicon (0<x≦1), as well as silicon-containing alloys containing titanium, vanadium, chromium, manganese, nickel, copper, lanthanum, etc. (e.g., LaSi ２ , VSi ２ , La—Si, Gd—Si, Ni—Si), or textured active materials (e.g., LaSi ２ / Si), and also SnSiO ３ , SnSiS ３ Examples of the active material include silicon and tin-containing active materials such as SiO ｘ can be used as an anode active material (semi-metal oxide) by itself, and can also be used as an anode active material (precursor material) that can be alloyed with lithium because it produces Si during operation of an all-solid-state secondary battery. Examples of anode active materials containing tin include Sn, SnO, and SnO ２ , SnS, SnS ２and active materials containing the above silicon and tin elements. Also, composite oxides with lithium oxide, for example, Li ２ SnO ２ The following can also be mentioned.

[0125] In the present invention, the above-mentioned negative electrode active material can be used without any particular limitation. However, in terms of battery capacity, a negative electrode active material that can be alloyed with lithium is a preferred embodiment. Among these, the above-mentioned silicon material or silicon-containing alloy (alloy containing silicon element) is more preferred, and it is even more preferred that the negative electrode active material contains silicon (Si) or a silicon-containing alloy.

[0126] The chemical formula of the compound obtained by the above calcination method can be measured by inductively coupled plasma (ICP) emission spectroscopy, or simply calculated from the difference in mass of the powder before and after calcination.

[0127] The shape of the negative electrode active material is not particularly limited, but is preferably particulate in the inorganic solid electrolyte-containing composition. When the negative electrode active material is particulate, the particle diameter of the negative electrode active material is not particularly limited, but is preferably 0.1 to 60 μm. The particle diameter of the negative electrode active material particles can be prepared in the same manner as the particle diameter of the inorganic solid electrolyte, and the measurement method is also the same as the method for measuring the particle diameter of the inorganic solid electrolyte.

[0128] The inorganic solid electrolyte-containing composition may contain one or more negative electrode active materials. The content of the negative electrode active materials in the inorganic solid electrolyte-containing composition is not particularly limited, and is preferably 10 to 90 mass %, more preferably 20 to 85 mass %, even more preferably 30 to 80 mass %, and still more preferably 40 to 75 mass %, based on 100 mass % of the solid content.

[0129] In the present invention, when the negative electrode active material layer is formed by charging the secondary battery, ions of a metal belonging to Group 1 or 2 of the periodic table that are generated in the all-solid-state secondary battery can be used instead of the above-mentioned negative electrode active material. The negative electrode active material layer can be formed by bonding these ions with electrons and precipitating them as a metal.

[0130] (Coating of active material) The surfaces of the positive electrode active material and the negative electrode active material may be coated with another metal oxide. Examples of the surface coating agent include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specific examples include titanate spinel, tantalum-based oxides, niobium-based oxides, and lithium niobate-based compounds. ４ Ti ５ O １２ , Li ２ Ti ２ O ５ , 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 P.O. 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 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. Furthermore, the particle surfaces of the positive electrode active material or the negative electrode active material may be surface-treated with actinic rays or an active gas (plasma, etc.) before or after the surface coating.

[0131] [Conductive Aid] The inorganic solid electrolyte-containing composition of the present invention preferably contains a conductive aid. For example, a silicon-containing active material as a negative electrode active material is preferably used in combination with a conductive aid. The conductive aid is not particularly limited, and any commonly known conductive aid can be used. For example, the conductive aid may be an electron conductive material such as graphites (e.g., natural graphite, artificial graphite), carbon blacks (e.g., acetylene black, ketjen black, furnace black), amorphous carbon (e.g., needle coke), carbon fibers (e.g., vapor-grown carbon fibers or carbon nanotubes), carbonaceous materials (e.g., graphene or fullerene), metal powders (e.g., copper, nickel), metal fibers, or conductive polymers (e.g., polyaniline, polypyrrole, polythiophene, polyacetylene, polyphenylene derivatives). In the present invention, when an active material and a conductive aid are used in combination, the conductive aid is one of the above conductive aids that does not insert or release ions (preferably Li ions) of a metal belonging to Group 1 or Group 2 of the periodic table during battery charging and discharging, and does not function as an active material. Therefore, among the conductive additives, 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 as conductive additives. Whether or not a conductive additive functions as an active material when the battery is charged and discharged is not uniquely determined, but is determined by the combination with the active material.

[0132] The conductive assistant is preferably in particulate form in the inorganic solid electrolyte-containing composition. When the conductive assistant is particulate, the particle size (volume average particle size) of the conductive assistant is not particularly limited, but is preferably, for example, 0.02 to 1.0 μm. The particle size of the conductive assistant can be adjusted in the same manner as the particle size of the inorganic solid electrolyte, and the measurement method is the same as the method for measuring the particle size of the inorganic solid electrolyte. The inorganic solid electrolyte-containing composition may contain one or two types of conductive assistant. When the inorganic solid electrolyte-containing composition of the present invention contains a conductive assistant, the content of the conductive assistant in the inorganic solid electrolyte-containing composition is preferably 0 to 10 mass %, more preferably 1 to 5 mass %, based on 100 mass % of the solid content.

[0133] [Lithium Salt] The inorganic solid electrolyte-containing composition of the present invention also preferably contains a lithium salt (supporting electrolyte). The lithium salt is preferably a lithium salt typically used in this type of product, and is not particularly limited. For example, the lithium salts described in paragraphs 0082 to 0085 of JP 2015-088486 A are preferred. When the inorganic solid electrolyte-containing composition of the present invention contains a lithium salt, the content of the lithium salt is preferably 0.1 parts by mass or more, more preferably 5 parts by mass or more, per 100 parts by mass of the inorganic solid electrolyte. The upper limit is preferably 50 parts by mass or less, more preferably 20 parts by mass or less.

[0134] [Dispersant] The inorganic solid electrolyte-containing composition of the present invention does not need to contain any dispersant other than the polymer binder (referred to as "other dispersant") because the above-mentioned polymer binder also functions as a dispersant, but it may contain other dispersants. As the other dispersant, one that is commonly used in all-solid-state secondary batteries can be appropriately selected and used. Generally, compounds intended for particle adsorption and steric and / or electrostatic repulsion are preferably used. The inorganic solid electrolyte-containing composition of the present invention may contain one or more other dispersants. When the inorganic solid electrolyte-containing composition of the present invention contains other dispersants, the content of the other dispersants can be appropriately determined and can be, for example, 3 mass% or less based on 100 mass% of the solid content of the inorganic solid electrolyte-containing composition.

[0135] [Other Additives] The inorganic solid electrolyte-containing composition of the present invention may contain, as appropriate, other components in addition to the above components, an ionic liquid, a thickener, a crosslinking agent (such as one that undergoes a crosslinking reaction by radical polymerization, condensation polymerization, or ring-opening polymerization), a polymerization initiator (such as one that generates an acid or radical by heat or light), an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, etc. The ionic liquid is contained to further improve ionic conductivity, and any known ionic liquid can be used without particular limitation. In addition, a polymer other than the above-mentioned binder-forming polymer, a commonly used binder, etc. may be contained.

[0136] <Preparation of Inorganic Solid Electrolyte-Containing Composition> The inorganic solid electrolyte-containing composition of the present invention can be prepared as a mixture, preferably as a slurry, by mixing an inorganic solid electrolyte, the above-mentioned polymer binder, a dispersion medium, preferably a conductive additive, and optionally a lithium salt and other components, for example, using various commonly used mixers. In the case of an electrode composition, an active material is further mixed. The mixing method is not particularly limited, and can be performed using known mixers such as a ball mill, a bead mill, a planetary mixer, a blade mixer, a roll mill, a kneader, a disk mill, a planetary mixer, a narrow-gap disperser, etc. The mixing conditions are also not particularly limited. For example, the components may be mixed all at once or sequentially. As mixing conditions, for example, the mixing temperature can be 15 to 50°C. Furthermore, the rotation speed of the planetary mixer or the like can be 200 to 3,000 rpm. The mixing atmosphere may be any of air, dry air (dew point -20°C or lower), and inert gas (e.g., argon gas, helium gas, nitrogen gas). Since inorganic solid electrolytes readily react with moisture, mixing is preferably carried out in dry air or an inert gas. The inorganic solid electrolyte-containing composition of the present invention has excellent solid particle dispersion properties, so it can be stored after preparation and does not need to be prepared each time it is used.

[0137] The inorganic solid electrolyte-containing composition of the present invention has excellent dispersion stability (redispersibility) of solid particles, and therefore can be stored after preparation, and does not need to be prepared every time it is used.

[0138] [Sheet for All-Solid-State Secondary Battery] The sheet for an all-solid-state secondary battery of the present invention is a sheet-like molded article capable of forming a constituent layer of an all-solid-state secondary battery, and includes various embodiments depending on its application. Examples include a sheet preferably used for a solid electrolyte layer (also referred to as a solid electrolyte sheet for an all-solid-state secondary battery), a sheet preferably used for an electrode, or a laminate of an electrode and a solid electrolyte layer (electrode sheet for an all-solid-state secondary battery), and the like. In the present invention, these various sheets are collectively referred to as a sheet for an all-solid-state secondary battery. In the present invention, each layer constituting the sheet for an all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

[0139] In the sheet for an all-solid-state secondary battery, the solid electrolyte layer or active material layer is formed from the inorganic solid electrolyte-containing composition of the present invention. Therefore, the layer formed from the inorganic solid electrolyte-containing composition of the present invention is formed from components derived from the inorganic solid electrolyte-containing composition (excluding the dispersion medium), and typically, solid particles (inorganic solid electrolyte, conductive additive, and active material) are adhered (bound) in a mixed state with a polymer binder. The sheet for an all-solid-state secondary battery can be incorporated into an all-solid-state secondary battery by appropriately peeling off the substrate or as is, thereby achieving low resistance (improved conductivity) and excellent high-voltage cycle characteristics of the all-solid-state secondary battery.

[0140] The solid electrolyte sheet for an all-solid-state secondary battery of the present invention may be any sheet having a solid electrolyte layer. It may be a sheet in which the solid electrolyte layer is formed on a substrate, or a sheet formed from the solid electrolyte layer without a substrate (a sheet from which the substrate has been peeled off). The solid electrolyte sheet for an all-solid-state secondary battery may have other layers in addition to the solid electrolyte layer. Examples of such other layers include a protective layer (release sheet), a current collector, and a coating layer. The solid electrolyte layer of the solid electrolyte sheet for an all-solid-state secondary battery is preferably formed from the inorganic solid electrolyte-containing composition of the present invention. The content of each component in the solid electrolyte layer is not particularly limited, but is preferably the same as the content of each component in the solid content of the inorganic solid electrolyte-containing composition of the present invention. The thickness of each layer constituting the solid electrolyte sheet for an all-solid-state secondary battery is the same as the thickness of each layer described in the all-solid-state secondary battery described below. The solid electrolyte sheet for an all-solid-state secondary battery of the present invention may be, for example, a sheet having, on a substrate, a layer composed of the inorganic solid electrolyte-containing composition of the present invention, a typical solid electrolyte layer, and a protective layer, in this order.

[0141] The substrate is not particularly limited as long as it can support the solid electrolyte layer, and examples thereof include sheets (plates) of materials described below in relation to the current collector, organic materials, inorganic materials, etc. Examples of organic materials include various polymers, specifically polyethylene terephthalate, polypropylene, polyethylene, cellulose, etc. Examples of inorganic materials include glass, ceramics, etc.

[0142] The electrode sheet for an all-solid-state secondary battery of the present invention (also simply referred to as "electrode sheet") may be an electrode sheet having an active material layer. It may be a sheet in which the active material layer is formed on a substrate (current collector), or a sheet formed from the active material layer without a substrate (a sheet from which the substrate has been peeled off). This electrode sheet typically has a current collector and an active material layer, but embodiments including a current collector, an active material layer, and a solid electrolyte layer in this order, as well as an electrode sheet having a current collector, an active material layer, a solid electrolyte layer, and an active material layer in this order, are also included. The solid electrolyte layer and active material layer of the electrode sheet are preferably formed from the inorganic solid electrolyte-containing composition of the present invention. The content of each component in this solid electrolyte layer or active material layer is not particularly limited, but is preferably synonymous with the content of each component in the solid content of the inorganic solid electrolyte-containing composition (electrode composition) of the present invention. The layer thickness of each layer constituting the electrode sheet of the present invention is the same as the layer thickness of each layer described in the all-solid-state secondary battery described below. The electrode sheet may also have other layers as described above. When the solid electrolyte layer or the active material layer is not formed from the inorganic solid electrolyte-containing composition of the present invention, it is formed from a normal constituent layer forming material.

[0143] In the sheet for an all-solid-state secondary battery of the present invention, at least one of the solid electrolyte layer and the active material layer is formed from the inorganic solid electrolyte-containing composition of the present invention. Therefore, the sheet for an all-solid-state secondary battery of the present invention has a flat surface layer in which uniformly arranged solid particles are firmly bound together while suppressing an increase in the interfacial resistance of the solid particles. Therefore, by using this layer as a constituent layer of an all-solid-state secondary battery, the all-solid-state secondary battery can achieve excellent high-potential cycle characteristics and low resistance (high conductivity). Furthermore, an electrode sheet for an all-solid-state secondary battery in which the active material layer on a current collector is formed from the inorganic solid electrolyte-containing composition of the present invention can firmly adhere the active material layer to the current collector. Thus, the sheet for an all-solid-state secondary battery of the present invention is suitable for use as a sheet-like member forming a constituent layer of an all-solid-state secondary battery.

[0144] [Method for Manufacturing Sheet for All-Solid-State Secondary Battery] The method for manufacturing the sheet for an all-solid-state secondary battery of the present invention is not particularly limited, and the sheet can be manufactured by forming each of the above-mentioned layers using the inorganic solid electrolyte-containing composition of the present invention. For example, a method is preferably used in which a layer (coated and dried) of the inorganic solid electrolyte-containing composition is formed on a substrate or a current collector (optionally via another layer) by film formation (coating and drying). This method allows for the production of a sheet for an all-solid-state secondary battery having a substrate or a current collector and a coated and dried layer. In particular, when a sheet for an all-solid-state secondary battery is produced by forming a film of the inorganic solid electrolyte-containing composition of the present invention on a current collector, the adhesion between the current collector and the active material layer can be strengthened. Here, the coated and dried layer refers to a layer formed by coating the inorganic solid electrolyte-containing composition of the present invention and drying the dispersion medium (i.e., a layer formed using the inorganic solid electrolyte-containing composition of the present invention and having a composition obtained by removing the dispersion medium from the inorganic solid electrolyte-containing composition of the present invention). The active material layer and the coated and dried layer may contain residual dispersion medium as long as it does not impair the effects of the present invention. The residual amount can be, for example, 3 mass% or less in each layer. In the method for producing a sheet for an all-solid-state secondary battery of the present invention, each step such as coating and drying will be described in the method for producing an all-solid-state secondary battery below.

[0145] In the method for producing a sheet for an all-solid-state secondary battery of the present invention, the coated and dried layer obtained as described above can also be pressed. The pressing conditions and the like will be explained in the method for producing an all-solid-state secondary battery described below. In addition, in the method for producing a sheet for an all-solid-state secondary battery of the present invention, the substrate, the protective layer (particularly the release sheet), and the like can also be peeled off.

[0146] [All-Solid-State Secondary Battery] The all-solid-state secondary battery of the present invention has a positive electrode active material layer, a negative electrode active material layer facing the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The all-solid-state secondary battery of the present invention is not particularly limited in its configuration as long as it has a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer, and for example, a known configuration related to all-solid-state secondary batteries can be adopted. The positive electrode active material layer is preferably formed on a positive electrode current collector to constitute a positive electrode. The negative electrode active material layer is preferably formed on a negative electrode current collector to constitute a negative electrode. In the present invention, each constituent layer (including the current collector, etc.) constituting the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

[0147] It is preferred that at least one of the negative electrode active material layer, positive electrode active material layer, and solid electrolyte layer be formed from the inorganic solid electrolyte-containing composition of the present invention. Another preferred embodiment is that at least one of the negative electrode active material layer and the positive electrode active material layer be formed from the inorganic solid electrolyte-containing composition of the present invention. Another preferred embodiment of the present invention is that all layers be formed from the inorganic solid electrolyte-containing composition of the present invention. In the present invention, forming the constituent layers of an all-solid-state secondary battery from the inorganic solid electrolyte-containing composition of the present invention includes forming the constituent layers from the all-solid-state secondary battery sheet of the present invention (provided that, if a layer other than the layer formed from the inorganic solid electrolyte-containing composition of the present invention is present, the sheet is formed from this layer). The all-solid-state secondary battery of the present invention, in which at least one constituent layer is formed from the inorganic solid electrolyte-containing composition of the present invention, exhibits low resistance (high conductivity) and excellent high-voltage cycle characteristics. The all-solid-state secondary battery of the present invention exhibits low resistance and high ionic conductivity, allowing for the extraction of large currents. If the active material layer or solid electrolyte layer is not formed from the inorganic solid electrolyte-containing composition of the present invention, known materials can be used. In the present invention, each of the constituent layers (including the current collector and the like) constituting the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

[0148] [Positive Electrode Active Material Layer, Solid Electrolyte Layer, Negative Electrode Active Material Layer] The active material layer or solid electrolyte layer formed from the inorganic solid electrolyte-containing composition of the present invention preferably has the same component types and their contents as those of the solid content of the inorganic solid electrolyte-containing composition of the present invention. The thicknesses of the negative electrode active material layer, solid electrolyte layer, and positive electrode active material layer are not particularly limited. The thickness of each layer is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm, taking into account the dimensions of a typical 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 and the negative electrode active material layer is 50 μm or more and less than 500 μm. The constituent layer having the above thickness may be a single layer (one application of the inorganic solid electrolyte-containing composition) or a multilayer (multiple applications of the inorganic solid electrolyte-containing composition). However, from the viewpoints of resistance reduction and productivity, it is preferable to form a single thick constituent layer using the inorganic solid electrolyte-containing composition of the present invention, which can be thickened by increasing the concentration. The thickness of the thickened single layer active material that can be preferably formed using the inorganic solid electrolyte-containing composition of the present invention can be, for example, 70 μm or more, and can also be 100 μm or more.

[0149] [Current Collector] The positive electrode active material layer and the negative electrode active material layer may each have a current collector on the side opposite to the solid electrolyte layer. The positive electrode current collector and the negative electrode current collector are preferably electronic conductors. In the present invention, either the positive electrode current collector or the negative electrode current collector, or both of them together, may be simply referred to as a current collector. Materials for forming the positive electrode current collector include aluminum, aluminum alloys, stainless steel, nickel, titanium, etc., as well as aluminum or stainless steel surfaces treated with carbon, nickel, titanium, or silver (thin films formed thereon), with aluminum and aluminum alloys being more preferred. Materials for forming the negative electrode current collector include aluminum, copper, copper alloys, stainless steel, nickel, titanium, etc., as well as aluminum, copper, copper alloys, or stainless steel surfaces treated with carbon, nickel, titanium, or silver, with aluminum, copper, copper alloys, and stainless steel being more preferred.

[0150] The current collector is usually in the form of a film sheet, but nets, punched materials, lath materials, porous materials, foamed materials, and molded fiber bodies can also be used. The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm. It is also preferable to make the surface of the current collector uneven by surface treatment.

[0151] [Other Configurations] In the present invention, functional layers or members may be appropriately interposed or disposed between or on the outside of the negative electrode current collector, negative electrode active material layer, solid electrolyte layer, positive electrode active material layer, and positive electrode current collector.

[0152] [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 as it is, but it is preferable to further encapsulate it in an appropriate case to make it into a dry battery. The case may be made of metal or resin (plastic). When a metal case is used, examples include aluminum alloys and stainless steel. The metal case is preferably divided into a positive electrode side case and a negative electrode side case, and is electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. The positive electrode side case and the negative electrode side case are preferably joined and integrated via a gasket to prevent short circuits.

[0153] Hereinafter, an all-solid-state secondary battery according to a preferred embodiment of the present invention will be described with reference to FIG. 1, but the present invention is not limited thereto.

[0154] FIG. 1 is a cross-sectional view schematically illustrating an all-solid-state secondary battery (lithium ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 of this embodiment has, as viewed from the negative electrode side, 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. Each layer is in contact with each other and has an adjacent structure. By adopting such a structure, electrons (e － ) is supplied to the battery, and lithium ions (Li ＋ On the other hand, during discharge, the lithium ions (Li ＋) is returned to the positive electrode side, and electrons are supplied to the operating part 6. In the illustrated example, a light bulb is used as a model for the operating part 6, and it is lit by discharge.

[0155] When an all-solid-state secondary battery having the layer structure shown in FIG. 1 is placed in a 2032-type coin case 11 (see, for example, FIG. 2 ), this all-solid-state secondary battery is referred to as a laminated body 12 for an all-solid-state secondary battery, and a battery produced by placing this laminated body 12 for an all-solid-state secondary battery in a 2032-type coin case 11 is sometimes referred to as a (coin-type) all-solid-state secondary battery 13.

[0156] <Positive Electrode Active Material Layer, Solid Electrolyte Layer, Negative Electrode Active Material Layer> In the all-solid-state secondary battery 10, the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 are all formed from the inorganic solid electrolyte-containing composition of the present invention. The inorganic solid electrolytes and polymer binders contained in the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 may be the same or different from each other. Furthermore, the conductive additives contained in the positive electrode active material layer 4 and the negative electrode active material layer 2 may be the same or different from each other. In the present invention, either the positive electrode active material layer or the negative electrode active material layer, or both together, may be simply referred to as the active material layer or the electrode active material layer. Furthermore, either the positive electrode active material or the negative electrode active material, or both together, may be simply referred to as the active material or the electrode active material.

[0157] The solid electrolyte layer contains an inorganic solid electrolyte having conductivity for metal ions belonging to Group 1 or 2 of the periodic table, a polymer binder, and the optional components described above within the scope of the present invention, and typically does not contain a positive electrode active material and / or a negative electrode active material. The positive electrode active material layer contains an inorganic solid electrolyte having conductivity for metal ions belonging to Group 1 or 2 of the periodic table, a polymer binder, a positive electrode active material, and the optional components described above within the scope of the present invention ... The thickness of the lithium metal layer can be, for example, 1 to 500 μm, regardless of the thickness of the negative electrode active material layer.

[0158] In the present invention, when the constituent layers are formed from the inorganic solid electrolyte-containing composition of the present invention, an all-solid-state secondary battery having excellent high-voltage cycle characteristics and low resistance can be realized.

[0159] <Current Collector> The positive electrode current collector 5 and the negative electrode current collector 1 are as described above. When the all-solid-state secondary battery 10 has a constituent layer other than the constituent layer formed from the inorganic solid electrolyte-containing composition of the present invention, a layer formed from a known constituent layer-forming material can also be applied. Furthermore, each layer may be composed of a single layer or multiple layers.

[0160] [[Manufacturing of All-Solid-State Secondary Battery]] All-solid-state secondary batteries can be manufactured by conventional methods. Specifically, all-solid-state secondary batteries can be manufactured by forming the above-mentioned layers using the inorganic solid electrolyte-containing composition of the present invention. Specifically, the all-solid-state secondary battery of the present invention can be manufactured by a method (a manufacturing method for an all-solid-state secondary battery sheet of the present invention) that includes (intervenes through) a step of applying the inorganic solid electrolyte-containing composition of the present invention to a suitable substrate (e.g., a metal foil serving as a current collector) and forming a coating film. More specifically, an inorganic solid electrolyte-containing composition containing a positive electrode active material is applied as a positive electrode material (positive electrode composition) to a metal foil serving as a positive electrode current collector to form a positive electrode active material layer, thereby producing a positive electrode sheet for an all-solid-state secondary battery. Next, an inorganic solid electrolyte-containing composition for forming a solid electrolyte layer is applied on this positive electrode active material layer to form a solid electrolyte layer. Furthermore, an inorganic solid electrolyte-containing composition containing a negative electrode active material is applied as a negative electrode material (negative electrode composition) to form a negative electrode active material layer on the solid electrolyte layer. By overlaying a negative electrode current collector (metal foil) on the negative electrode active material layer, an all-solid-state secondary battery can be obtained in which a solid electrolyte layer is sandwiched between a positive electrode active material layer and a negative electrode active material layer. This can also be enclosed in a case to form a desired all-solid-state secondary battery. Alternatively, the method of forming each layer can be reversed, and an all-solid-state secondary battery can be produced by forming a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer on the negative electrode current collector, and then overlaying the positive electrode current collector.

[0161] Another method includes the following. That is, a positive electrode sheet for an all-solid-state secondary battery is prepared as described above. Furthermore, an inorganic solid electrolyte-containing composition containing a negative electrode active material is applied as a negative electrode material (negative electrode composition) to a metal foil serving as a negative electrode current collector to form a negative electrode active material layer, thereby preparing a negative electrode sheet for an all-solid-state secondary battery. Next, a solid electrolyte layer is formed on the active material layer of either of these sheets as described above. Furthermore, the other of the positive electrode sheet for an all-solid-state secondary battery and the negative electrode sheet for an 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 manner, an all-solid-state secondary battery can be manufactured. Another method includes the following. That is, a positive electrode sheet for an all-solid-state secondary battery and a negative electrode sheet for an all-solid-state secondary battery are prepared as described above. Separately from this, an inorganic solid electrolyte-containing composition is applied to a substrate to prepare a solid electrolyte sheet for an all-solid-state secondary battery comprising a solid electrolyte layer. Furthermore, the solid electrolyte layer peeled from the substrate is sandwiched between the positive electrode sheet for an all-solid-state secondary battery and the negative electrode sheet for an all-solid-state secondary battery. In this way, an all-solid-state secondary battery can be manufactured.

[0162] Furthermore, a positive electrode sheet for an all-solid-state secondary battery or a negative electrode sheet for an all-solid-state secondary battery, and a solid electrolyte sheet for an all-solid-state secondary battery are produced as described above. Next, the positive electrode sheet for an all-solid-state secondary battery or the negative electrode sheet for an all-solid-state secondary battery and the solid electrolyte sheet for an all-solid-state secondary battery are overlapped with each other in a state in which the positive electrode active material layer or the negative electrode active material layer is in contact with the solid electrolyte layer, and pressurized. In this way, the solid electrolyte layer is transferred to the positive electrode sheet for an all-solid-state secondary battery or the negative electrode sheet for an all-solid-state secondary battery. Thereafter, the solid electrolyte layer from which the substrate of the solid electrolyte sheet for an all-solid-state secondary battery has been peeled is overlapped with the negative electrode sheet for an all-solid-state secondary battery or the positive electrode sheet for an all-solid-state secondary battery (in a state in which the negative electrode active material layer or the positive electrode active material layer is in contact with the solid electrolyte layer) and pressurized. In this way, an all-solid-state secondary battery can be produced. The pressurization method and pressurization conditions in this method are not particularly limited, and the method and pressurization conditions described in the pressurization step below can be applied.

[0163] The solid electrolyte layer or the like can also be formed, for example, by pressure molding an inorganic solid electrolyte-containing composition or the like on a substrate or an active material layer under pressure conditions described below. In the above-mentioned manufacturing method, the inorganic solid electrolyte-containing composition of the present invention may be used for any one of the positive electrode composition, the inorganic solid electrolyte-containing composition, and the negative electrode composition. It is preferable to use the inorganic solid electrolyte-containing composition of the present invention for the inorganic solid electrolyte-containing composition or at least one of the positive electrode composition and the negative electrode composition, and the inorganic solid electrolyte-containing composition of the present invention can be used for either composition. When forming a solid electrolyte layer or an active material layer with a composition other than the inorganic solid electrolyte-containing composition of the present invention, examples of the material include commonly used compositions. Alternatively, instead of forming a negative electrode active material layer during the production of an all-solid-state secondary battery, the negative electrode active material layer can be formed by bonding ions of a metal belonging to Group 1 or Group 2 of the periodic table that have accumulated on the negative electrode current collector during initialization or charging during use, as described below, with electrons and depositing the metal on the negative electrode current collector or the like.

[0164] [Formation of Each Layer (Film Formation)] The coating method of the inorganic solid electrolyte-containing composition is not particularly limited and can be selected appropriately. Examples include coating (preferably wet coating), spray coating, spin coating, dip coating, slit coating, stripe coating, and bar coating. The coating temperature is not particularly limited, and examples thereof include a temperature range of about room temperature (e.g., 15 to 30°C) without heating. In this case, the inorganic solid electrolyte-containing composition may be subjected to a drying treatment after each coating, or may be subjected to a drying treatment after multilayer coating. 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. Heating within this temperature range can remove the dispersion medium and create a solid state (coated, dried layer). In addition, it is preferable not to raise the temperature too high, as this avoids damaging the components of the all-solid-state secondary battery. This allows the all-solid-state secondary battery to exhibit excellent overall performance, and to obtain good binding properties and good ionic conductivity.

[0165] After applying the inorganic solid electrolyte-containing composition, after stacking the constituent layers, or after fabricating the all-solid-state secondary battery, it is preferable to pressurize each layer or the all-solid-state secondary battery. It is also preferable to pressurize each layer in a stacked state. Examples of pressurizing methods include a hydraulic cylinder press. The pressure is not particularly limited, and is generally in the range of 5 to 1500 MPa. The applied inorganic solid electrolyte-containing composition may be heated simultaneously with pressing. 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. It can also be pressed at a temperature higher than the glass transition temperature of the polymer contained in the polymer binder. However, the temperature generally does not exceed the melting point of the polymer. Pressing may be performed after the application solvent or dispersion medium has been dried in advance, or while the solvent or dispersion medium remains. The compositions may be applied simultaneously, or application, drying, and pressing may be performed simultaneously and / or sequentially. After being applied to separate substrates, the compositions may be laminated by transfer.

[0166] The atmosphere in the film-forming method (coating, drying, and pressurization (under heating)) is not particularly limited, and may be any of the following: atmospheric air, dry air (dew point -20°C or lower), and inert gas (e.g., argon gas, helium gas, nitrogen gas). High pressure may be applied for a short period of time (e.g., within a few hours), or moderate pressure may be applied for a long period of time (one day or more). In the case of a sheet other than an all-solid-state secondary battery sheet, for example, an all-solid-state secondary battery, a restraining device for the all-solid-state secondary battery (e.g., screw tightening pressure) may be used to continuously apply moderate pressure. The pressing pressure may be uniform or may vary across the pressed portion, such as the sheet surface. The pressing pressure may be varied depending on the area or film thickness of the pressed portion. The same portion may also be subjected to different pressures in stages. The pressing surface may be smooth or roughened.

[0167] The inorganic solid electrolyte-containing composition of the present invention can maintain excellent dispersion stability and handleability, as well as initial dispersibility, even when the solid content concentration is increased. Therefore, the inorganic solid electrolyte-containing composition can be applied at a high solid content concentration.

[0168] [Initialization] The all-solid-state secondary battery produced as described above is preferably initialized after production or before use. The initialization is not particularly limited, and can be performed, for example, by carrying out initial charge and discharge under an elevated pressure, and then releasing the pressure until the pressure reaches the general operating pressure of an all-solid-state secondary battery.

[0169] [[Uses of All-Solid-State Secondary Battery]] The all-solid-state secondary battery of the present invention can be used in a variety of applications. While there are no particular limitations on the application mode, examples of applications include electronic devices such as notebook computers, pen-input PCs, mobile PCs, e-book players, mobile phones, cordless phone handsets, pagers, handheld terminals, portable fax machines, portable copiers, portable printers, headphone stereos, video movie players, LCD televisions, handheld vacuum cleaners, portable CD players, mini-discs, electric shavers, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, and backup power supplies. Other consumer applications include automobiles (e.g., electric vehicles), electric vehicles, motors, lighting fixtures, toys, game consoles, road conditioners, clocks, flash devices, cameras, and medical devices (e.g., pacemakers, hearing aids, and shoulder massagers). Furthermore, the all-solid-state secondary battery can be used for various military and space applications. It can also be combined with solar cells.

[0170] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited thereto. In the following examples, "parts" and "%" representing compositions are based on mass unless otherwise specified. In the present invention, "room temperature" means 25°C.

[0171] Synthesis Example: Polymer Synthesis and Binder Solution Preparation. The polymers shown in the following chemical formulas and in Table 2 were synthesized as follows, and binder solutions or dispersions were prepared. Synthesis Example B-1: Synthesis of Polymer B-1 and Preparation of Binder Solution B-1. 0.2 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to a 200 mL graduated cylinder and dissolved in 10 g of butyl butyrate to prepare an initiator solution. 30 g of butyl butyrate, 6.0 g of isopropylacrylamide, 42 g of 2-ethylhexyl methacrylate, and 12 g of dodecyl acrylate were added to a 500 mL three-neck flask and stirred at 80°C under a nitrogen stream. The initiator solution was then added dropwise over 3 hours. After the addition was completed and the mixture was stirred for 2 hours, a solution of 0.1 g of polymerization initiator V-601 dissolved in 2 g of butyl butyrate was added and stirred for another 2 hours. The temperature was then raised to 95° C., and the mixture was stirred for 3 hours, and 100 g of butyl butyrate was added to dilute the mixture. Thus, polymer B-1 was synthesized, and binder solution B-1 (concentration 30% by mass) made of this polymer was obtained.

[0172] [Synthesis Examples B-2 to B-14: Synthesis of Polymers B-2 to B-14, and Preparation of Binder Solutions B-2 to B-14] Polymers B-2 to B-14 were synthesized in the same manner as in Synthesis Example B-1, except that compounds were used to induce each structural unit so that polymers B-2 to B-14 would have the following chemical formulas and compositions (types and contents of structural units) shown in Table 2, and the amount of polymerization initiator was adjusted so that the weight-average molecular weight would be as shown in Table 2, and binder solutions B-2 to B-14 composed of each polymer were obtained, respectively.

[0173] Synthesis Examples T-1, T-2, T-5, and T-6: Synthesis of Polymers T-1, T-2, T-5, and T-6, and Preparation of Binder Solutions T-1, T-2, T-5, and T-6 Polymers T-1, T-2, T-5, and T-6 were synthesized in the same manner as in Synthesis Example B-1, except that in Synthesis Example B-1, compounds were used that lead to each structural unit so that polymers T-1, T-2, T-5, and T-6 would have the following chemical formulas and compositions (types and contents of structural units) shown in Table 2, and the amount of polymerization initiator was adjusted so that the weight-average molecular weight would be as shown in Table 2, and binder solutions T-1, T-2, T-5, and T-6 composed of each polymer were obtained, respectively.

[0174] [Synthesis Example T-3: Synthesis of Polymer T-3, and Preparation of Binder Liquid T-3] Polymer T-3 was synthesized in the same manner as in Synthesis Example B-1, except that in Synthesis Example B-1, compounds were used that would lead to each structural unit so that Polymer T-3 would have the following chemical formula and the composition (types and contents of structural units) shown in Table 2, and the amount of polymerization initiator was adjusted so that the weight average molecular weight would be as shown in Table 2. This Polymer T-3 was insoluble in the dispersion medium, and binder liquid T-3 could not be prepared.

[0175] [Synthesis Example T-4: Synthesis of Polymer T-4, and Preparation of Binder Dispersion T-4] 269.0 g of toluene was charged into a 1-liter three-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, and the temperature was raised to 80 ° C. under a nitrogen stream. Next, a monomer solution consisting of 150.2 g of methyl methacrylate, 381.6 g of lauryl methacrylate, 5.3 g of V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 4.7 g of mercaptopropionic acid was added dropwise to the three-neck flask at a constant rate so that the dropwise addition was completed within 2 hours. After completion of the dropwise addition of the monomer solution, the mixture was stirred for 2 hours, then heated to 95 ° C., and stirred for another 2 hours. Subsequently, 0.3 g of p-methoxyphenol, 31.8 g of glycidyl methacrylate, and 6.4 g of tetrabutylammonium bromide were added to the resulting reaction mixture, and the mixture was heated to 120 ° C. and stirred for 3 hours. The reaction solution was then cooled to room temperature, poured into 2 L of stirred methanol, and allowed to stand for a while. The supernatant was decanted, and the resulting solid was dissolved in 1,200 g of xylene. The solvent was distilled off under reduced pressure until the solid content reached 40%, yielding a macromonomer solution. The weight-average molecular weight of the macromonomer was 2.0 × 10 ４ The result was: 225 g of butyl butyrate and 300 g of the macromonomer solution (solid content 40.0%) were then placed in a 2-liter three-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, and the temperature was raised to 80°C under a nitrogen stream. Next, 200.0 g of methyl methacrylate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 80.0 g of diethylacrylamide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), and 2.40 g of polymerization initiator V-601 (trade name, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were added to the three-neck flask, and the monomer solution dissolved in 155.8 g of butyl butyrate was added dropwise over 2 hours. After completion of the dropwise addition, the temperature was raised to 90°C and the mixture was stirred for 2 hours. In this way, a binder dispersion T-4 (concentration 30% by mass) containing polymer T-4 was obtained. In this binder dispersion T-4, the particle size of polymer T-4 was measured by the same method as above for inorganic solid electrolytes, and was found to be 150 nm.

[0176] The chemical formula of each synthesized polymer is shown below: In the chemical formula, "Me" represents a methyl group.

[0177]

[0178]

[0179] Table 2 shows the glass transition temperature (Tg) of the homopolymer and the glass transition temperature (Tg) of each polymer for each structural unit. Table 2 also shows the weight-average molecular weight of each synthesized polymer. The weight-average molecular weight was measured by the above-mentioned method. Furthermore, the "Polar Functional Group (a)" column in Table 2 shows the type of polar functional group (a) possessed by the polymer. The "State" column in Table 2 shows the state of the polymer binder in each composition described below, as determined by measuring its solubility in the dispersion medium using the above-mentioned method, and determining whether it was "dissolved" or "particulate" (not dissolved but dispersed in particulate form). Polymer T-3 was labeled "insoluble" because it neither dissolved nor dispersed in the dispersion medium. The "content" listed in Table 2 is a value calculated from the charge ratio of each compound during preparation.

[0180]

[0181] In the tables, a "-" in the structural unit column indicates that the corresponding structural unit is not present. The abbreviations indicating the type of each structural component (the compound name from which each structural component is derived) in Table 2 are as shown in Table 1. CHVE represents cyclohexyl vinyl ether, HBVE represents 4-hydroxybutyl vinyl ether, and MM-1 represents the macromonomer MM-1 synthesized in Synthesis Example T-4.

[0182] [Synthesis Example A: Synthesis of sulfide-based inorganic solid electrolyte] The sulfide-based inorganic solid electrolyte was synthesized with reference to the non-patent literature of T. Ohtomo, A. Hayashi, M. Tatsumisago, Y. Tsuchida, S. Hama, K. Kawamoto, Journal of Power Sources, 233, (2013), pp. 231-235, and A. Hayashi, S. Hama, H. Morimoto, M. Tatsumisago, T. Minami, Chem. Lett., (2001), pp. 872-873. Specifically, lithium sulfide (Li ２S, manufactured by Aldrich, purity >99.98%) 2.42 g and diphosphorus pentasulfide (P ２ S ５ 3.90 g of Li, manufactured by Aldrich, purity >99%) was weighed out and placed in an agate mortar and mixed for 5 minutes using an agate pestle. ２ S and P ２ S ５ The mixing ratio is Li in molar ratio. ２ S:P ２ S ５ = 75:25. Next, 66 g of zirconia beads having a diameter of 5 mm was added to a 45 mL zirconia container (manufactured by Fritsch), and the entire amount of the mixture of lithium sulfide and diphosphorus pentasulfide was added, and the container was completely sealed under an argon atmosphere. The container was set in a planetary ball mill P-7 (trade name, manufactured by Fritsch), and mechanical milling was performed for 20 hours at a temperature of 25 ° C. and a rotation speed of 510 rpm to obtain 6.20 g of a yellow powder sulfide-based inorganic solid electrolyte (Li-P-S-based glass, hereinafter sometimes referred to as LPS). The particle diameter of the Li-P-S-based glass was 15 μm.

[0183] [Example 1] Each composition shown in Tables 3-1 to 3-4 (collectively referred to as Table 3) was prepared as follows. Note that, since binder solution T-3 could not be prepared, Example 1 was not performed. <Preparation of Inorganic Solid Electrolyte-Containing Composition> 2.8 g of the inorganic solid electrolyte LPS synthesized in Synthesis Example A, 0.08 g (solid content by mass) of binder solution or binder dispersion, and butyl butyrate as the dispersion medium described below so that the content of the dispersion medium in the composition was 48 mass% were added to a container for a planetary mixer (ARE-310, manufactured by Thinky Corporation). Thereafter, this container was set in the planetary mixer ARE-310 (trade name). The mixture was mixed for 5 minutes under conditions of 25°C and a rotation speed of 2000 rpm to prepare inorganic solid electrolyte-containing compositions (slurries) K-1 to K-14, respectively. In addition, in the preparation of inorganic solid electrolyte-containing composition K-1, the binder solution or dispersion was changed to the binder solution or dispersion shown in Table 3-4, and the content of each component was set to the content shown in the same table. Inorganic solid electrolyte-containing compositions (slurries) Kc11 to Kc16 (excluding Kc13) were prepared in the same manner.

[0184] <Preparation of Positive Electrode Composition> 2.8 g of the inorganic solid electrolyte LPS synthesized in Synthesis Example A and xylene as a dispersion medium were placed in a container for a planetary mixer (ARE-310, manufactured by Thinky Corporation) so that the content of the dispersion medium in the positive electrode composition was 30 mass %. Thereafter, this container was set in the planetary mixer ARE-310 (trade name) and mixed for 2 minutes at a temperature of 25°C and a rotation speed of 2000 rpm. Thereafter, LiNi as a positive electrode active material was added to this container in the proportions shown in Table 3-2. １／３ Co １／３ Mn １／３ O ２ (NMC, manufactured by Aldrich), acetylene black (AB) as a conductive additive, and the binder solution shown in Table 3-2 below were added, and the mixture was set in a planetary mixer ARE-310 (trade name) and mixed for 2 minutes at 25°C and 2000 rpm to prepare positive electrode compositions (slurries) PK-1 to PK-14. Furthermore, in the preparation of positive electrode composition PK-1, the binder solution or dispersion was changed to the binder solution or dispersion shown in Table 3-4, and the contents of each component were set to the contents shown in the same table. Positive electrode compositions (slurries) PKc21 to PKc26 (excluding PKc23) were prepared in the same manner.

[0185] <Preparation of Negative Electrode Composition> 2.8 g of the inorganic solid electrolyte LPS synthesized in Synthesis Example A, 0.06 g (solid content by mass) of the binder solution or dispersion shown in Table 3-3 below, and xylene as a dispersion medium so that the content of the dispersion medium in the negative electrode composition was 48 mass% were placed in a container for a planetary planetary mixer (ARE-310). This container was then set in a planetary planetary mixer (ARE-310) manufactured by Thinky Corporation, and the mixture was mixed for 2 minutes at 25°C and a rotation speed of 2000 rpm. Thereafter, 3.36 g of graphite (Gr, manufactured by Aldrich) as the negative electrode active material shown in Table 3-3 below (Examples NK-4, NK-10, and NK-13 contain 3.11 g of graphite and 0.25 g of carbon nanotubes (VGCF) as a conductive additive) was added, and the mixture was similarly set in a planetary mixer ARE-310 (trade name) and mixed for 2 minutes at 25 ° C. and 2000 rpm to prepare negative electrode compositions (slurries) NK-1 to NK-14, respectively. In addition, in the preparation of negative electrode composition NK-1, the binder solution or dispersion was changed to the binder solution or dispersion shown in Table 3-4, and the content of each component was set to the content shown in the same table. In the same manner, negative electrode compositions (slurries) NKc21 to NKc26 (excluding NKc23) were each prepared.

[0186] In Table 3, the composition content is the content (mass%) relative to the total mass of the composition, and the solid content is the content (mass%) relative to 100 mass% of the solid content of the composition, and units are omitted in the table.

[0187]

[0188]

[0189]

[0190]

[0191] LPS: LPS synthesized in Synthesis Example A NMC: LiNi １／３ Co １／３ Mn １／３ O ２ Gr: graphite (manufactured by Aldrich) AB: acetylene black VGCF: carbon nanofiber

[0192] <Preparation of Solid Electrolyte Sheets for All-Solid-State Secondary Batteries> Each of the inorganic solid electrolyte-containing compositions shown in the "Solid Electrolyte Composition No." column of Table 4-1 or Table 4-4 obtained above was applied to a 20 μm-thick aluminum foil using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.) and heated at 80°C for 2 hours to dry the inorganic solid electrolyte-containing composition (removing the dispersion medium). Thereafter, using a heat press, the dried inorganic solid electrolyte-containing composition was heated and pressed at a temperature of 120°C and a pressure of 10 MPa for 10 seconds to prepare solid electrolyte sheets for all-solid-state secondary batteries (referred to as solid electrolyte sheets in Tables 4-1 and 4-4) 101 to 114 and c11 to c16 (excluding c13), respectively. The film thickness of the solid electrolyte layer was 50 μm.

[0193] <Preparation of Positive Electrode Sheet for All-Solid State Secondary Battery> Each of the positive electrode compositions shown in the "Electrode Composition No." column in Table 4-2 or Table 4-4 obtained above was applied to a 20 μm thick aluminum foil using a Baker-type applicator (product name: SA-201), heated at 80 ° C. for 1 hour, and further heated at 110 ° C. for 1 hour to dry the positive electrode composition (to remove the dispersion medium). Thereafter, using a heat press, the dried positive electrode composition was pressed (10 MPa, 1 minute) at 25 ° C. to prepare positive electrode sheets for all-solid state secondary batteries (referred to as positive electrode sheets in Tables 4-2 and 4-4) 201 to 214 and c21 to c26 (excluding c23) having a positive electrode active material layer with a film thickness of 100 μm.

[0194] <Preparation of negative electrode sheets for all-solid-state secondary batteries> Each of the negative electrode compositions shown in the "Electrode composition No." column in Table 4-3 or Table 4-4 obtained above was applied to a copper foil having a thickness of 20 μm using a Baker-type applicator (product name: SA-201), heated at 80 ° C. for 1 hour, and further heated at 110 ° C. for 1 hour to dry the negative electrode composition (to remove the dispersion medium). Thereafter, using a heat press, the dried negative electrode composition was pressed (10 MPa, 1 minute) at 25 ° C. to prepare negative electrode sheets for all-solid-state secondary batteries (referred to as negative electrode sheets in Tables 4-3 and 4-4) 301 to 314 and c31 to c36 (excluding c33) having a negative electrode active material layer with a film thickness of 70 μm.

[0195] <Evaluation 1: Storage Stability Test (Redispersibility)> For each composition prepared as described above, LPS, polymer binder, dispersion medium, active material, and conductive additive were mixed in the same proportions as the composition content and solid content ratios shown in Table 3 under the same preparation conditions as for each composition to prepare a dispersibility evaluation composition (slurry). For each prepared composition, the occurrence (presence or absence) of solid particle aggregates was confirmed using a grind meter (manufactured by Asahi Research Institute Co., Ltd.). The size of the aggregates at this time was designated X (μm) and used as an index of initial dispersibility. Meanwhile, each prepared composition was left at 25°C for 24 hours and then remixed at a temperature of 25°C using a planetary ball mill P-7 (trade name). The rotation speed and time during remixing were the same as those for the preparation conditions for each composition (25°C, 2000 rpm, 2 minutes in the case of electrode compositions). For the remixed composition, the occurrence (presence or absence) of solid particle aggregates was confirmed using the grind meter. The size of the aggregates at this time was designated Y (μm) and used as an index of redispersibility after storage. The size of the aggregates was determined by the point at which the applied product on the grindmeter showed noticeable spots (see JIS K-5600-2-5 6.6). The tendency for aggregates to form (aggregation or sedimentation) was evaluated as the storage stability (redispersibility of solid particles) of the composition based on whether the aggregate sizes X and Y fell within the following evaluation criteria. In this test, the smaller the aggregate size X, the better the initial dispersibility, and the smaller the aggregate size Y, the better the storage stability. If a composition can effectively inhibit (re)aggregation or precipitation of solid particles over time (excellent dispersion stability), the composition can reproduce the excellent dispersibility immediately after preparation even for solid particles that have once aggregated or precipitated, demonstrating excellent storage stability. In this test, an evaluation of aggregate size Y of "C" or higher was considered acceptable, and if size Y was 8 μm or less (evaluation criterion "C" or higher), aggregate size X was also included in the evaluation. The results are shown in Tables 4-1 to 4-4. Hereinafter, Tables 4-1 to 4-4 are collectively referred to as Table 4.- Evaluation criteria - A: Y≦5 μm and X≦5 μm B: 5 μm<Y≦8 μm and 5 μm<X≦8 μm C: 5 μm<Y≦8 μm and 8 μm<X≦12 μm D: 8 μm<Y≦10 μm E: 10 μm<Y≦20 μm F: 20 μm<Y.

[0196] <Evaluation 2: Handling Test> A slurry with a solid content concentration of 75% by mass was prepared in the same manner as each of the prepared compositions, except for the dispersion medium, with the same mixing ratio. A 2 mL plastic dropper (manufactured by Atect Co., Ltd.) was placed vertically so that the tip 10 mm was below the interface of the slurry, and the slurry was sucked at 25°C for 10 seconds, and the mass W of the plastic dropper containing the sucked slurry was measured. The tare weight (weight) of the plastic dropper was W ０ When this is done, the slurry mass W-W ０ If the amount of solids in the slurry was less than 0.1 g, it was determined that the slurry could not be sucked up with a dropper. If the slurry could not be sucked up with a dropper, the upper limit of the solids concentration that could be sucked up with a dropper was determined by gradually adding the dispersion medium. The handleability of the composition (whether the composition had a viscosity appropriate for forming a flat, well-formed layer) was evaluated based on whether the obtained upper limit of the solids concentration fell within any of the following evaluation criteria. The solids concentration was calculated by placing 0.30 g of the prepared slurry on an aluminum cup, heating it at 120°C for 2 hours, and distilling off the dispersion medium. In this test, the higher the upper limit of the solids concentration, the better the handleability, and a rating of "C" or higher was considered a passing level. The results are shown in Table 4. - Evaluation criteria - A: Upper limit solid concentration ≧ 70% B: 70% > upper limit solid concentration ≧ 60% C: 60% > upper limit solid concentration ≧ 50% D: 50% > upper limit solid concentration ≧ 40% E: 40% > upper limit solid concentration ≧ 30% F: 30% > upper limit solid concentration

[0197] <Evaluation 3: Adhesion Test> The adhesion of the solid particles and the current collector to each of the obtained all-solid-state secondary battery sheets was evaluated. Each prepared all-solid-state secondary battery sheet was cut into a rectangle measuring 3 cm wide x 14 cm long. Using a cylindrical mandrel tester (product code 056, mandrel diameter 10 mm, manufactured by Allgood), one longitudinal end of the cut-out sheet specimen was fixed to the tester, and the sheet specimen was positioned so that the cylindrical mandrel was in contact with the center of the sheet specimen. The other longitudinal end of the sheet specimen was pulled along the length with a force of 5 N while being bent 180° around the periphery of the mandrel (with the mandrel as the axis). The sheet specimen was set with the solid electrolyte layer or active material layer facing away from the mandrel (the substrate or current collector facing the mandrel) and the width direction parallel to the axis of the mandrel. The test was performed by gradually decreasing the mandrel diameter from 32 mm. The evaluation was performed by measuring the minimum diameter at which defects (cracks, breaks, chips, etc.) due to breakdown of the solid particle adhesion in the solid electrolytic layer or active material layer, and separation of the solid electrolytic layer or active material layer from the current collector were not observed when the solid electrolytic layer or active material layer was wound around a mandrel and when the solid electrolytic layer or active material layer was unwound and restored to a sheet shape, and determining which of the following evaluation criteria this minimum diameter fell under. In this test, the smaller the minimum diameter, the stronger the adhesion strength of the solid particles constituting the solid electrolytic layer or active material layer and the stronger the adhesion strength between the solid electrolytic layer or active material layer and the current collector, and an evaluation criterion of "C" or higher is a pass level. - Evaluation Criteria - A: Minimum diameter < 5 mm B: 5 mm ≦ minimum diameter < 6 mm C: 6 mm ≦ minimum diameter < 8 mm D: 8 mm ≦ minimum diameter < 10 mm E: 10 mm ≦ minimum diameter < 14 mm F: 14 mm ≦ minimum diameter < 25 mm G: 25 mm ≦ minimum diameter

[0198]

[0199]

[0200]

[0201]

[0202] <Production of All-Solid State Secondary Battery> First, a positive electrode sheet for an all-solid state secondary battery having a solid electrolyte layer and a negative electrode sheet for an all-solid state secondary battery having a solid electrolyte layer were produced, to be used in the production of an all-solid state secondary battery.

[0203] - Preparation of cathode sheets for all solid state secondary batteries having solid electrolyte layer - On the cathode active material layer of each of the cathode sheets for all solid state secondary batteries shown in the "Electrode active material layer (sheet No.)" column of Table 5, the solid electrolyte sheet prepared above shown in the "Solid electrolyte layer (sheet No.)" column of Table 5 was superimposed so that the solid electrolyte layer was in contact with the cathode active material layer, and the sheets were transferred (laminated) by applying a pressure of 50 MPa at 25°C using a press, and then applying a pressure of 600 MPa at 25°C to prepare cathode sheets for all solid state secondary batteries Nos. 201 to 214 and c21 to c26 (excluding c23) having a solid electrolyte layer with a thickness of 25 μm (cathode active material layer thickness of 50 μm).

[0204] - Preparation of negative electrode sheets for all solid state secondary batteries having solid electrolyte layer - On the negative electrode active material layer of each negative electrode sheet for all solid state secondary batteries shown in the "Electrode active material layer (sheet No.)" column of Table 5, the solid electrolyte sheet prepared above shown in the "Solid electrolyte layer (sheet No.)" column of Table 5 was superimposed such that the solid electrolyte layer was in contact with the negative electrode active material layer, and a press was used to transfer (laminate) the sheets at 25°C and a pressure of 50 MPa, followed by pressure at 25°C and 600 MPa to prepare negative electrode sheets for all solid state secondary batteries 301 to 314 and c31 to c36 (excluding c33) each having a solid electrolyte layer with a thickness of 25 μm (negative electrode active material layer thickness of 40 μm).

[0205] All-solid-state secondary battery No. 101 having the layer structure shown in FIG. 1 was fabricated as follows. The all-solid-state secondary battery positive electrode sheet No. 201 (the aluminum foil of the solid electrolyte-containing sheet had already been peeled off) provided with the solid electrolyte layer obtained above was cut into a disk shape with a diameter of 14.5 mm and placed in a stainless steel 2032-type coin case 11 incorporating a spacer and a washer (not shown in FIG. 2 ) as shown in FIG. 2 . Next, a lithium foil cut into a disk shape with a diameter of 15 mm was placed on top of the solid electrolyte layer. Stainless steel foil was then placed on top of that, and the 2032-type coin case 11 was then crimped to fabricate all-solid-state secondary battery No. 101 shown in FIG. 2 . The all-solid-state secondary battery fabricated in this manner had the layer structure shown in FIG. 1 (where the lithium foil corresponds to the negative electrode active material layer 2 and the negative electrode current collector 1).

[0206] All solid state secondary batteries Nos. 102 to 114 and c101 to c106 (excluding c103) were produced in the same manner as in the production of all solid state secondary battery No. 101, except that in the production of all solid state secondary battery No. 101, positive electrode sheets for all solid state secondary batteries having a solid electrolyte layer, represented by the numbers shown in the "Electrode active material layer (sheet No.)" column in Table 5, were used instead of positive electrode sheet No. 201 for all solid state secondary batteries having a solid electrolyte layer.

[0207] All-solid-state secondary battery No. 115 having the layer structure shown in FIG. 1 was fabricated as follows. The solid electrolyte-containing negative electrode sheet No. 301 for all-solid-state secondary batteries obtained above (the aluminum foil of the solid electrolyte-containing sheet had already been peeled off) was cut into a disk shape with a diameter of 14.5 mm and placed in a stainless steel 2032-type coin case 11 incorporating a spacer and a washer (not shown in FIG. 2 ), as shown in FIG. 2 . Next, a positive electrode sheet (positive electrode active material layer) punched to a diameter of 14.0 mm from the positive electrode sheet for all-solid-state secondary batteries fabricated below was placed on top of the solid electrolyte layer. A stainless steel foil (positive electrode current collector) was further placed on top of this to form an all-solid-state secondary battery laminate 12 (a laminate consisting of stainless steel foil-aluminum foil-positive electrode active material layer-solid electrolyte layer-negative electrode active material layer-copper foil). The 2032-type coin case 11 was then crimped to produce all-solid-state secondary battery No. 115 shown in FIG. 2 .

[0208] The positive electrode sheet for a solid secondary battery used in the production of all-solid-state secondary battery No. 115 was prepared as follows. - Preparation of positive electrode composition - 180 zirconia beads with a diameter of 5 mm were placed in a 45 mL zirconia container (manufactured by Fritsch), and 2.7 g of the LPS synthesized in Synthesis Example A above, 0.3 g of KYNAR FLEX 2500-20 (trade name, PVdF-HFP: polyvinylidene fluoride hexafluoropropylene copolymer, manufactured by Arkema) as a solid content mass, and 22 g of butyl butyrate were added. This container was placed in a Fritsch planetary ball mill P-7 (trade name) and stirred at 25°C at 300 rpm for 60 minutes. Thereafter, LiNi was added as a positive electrode active material. １／３ Co １／３ Mn １／３ O ２ 7.0 g of (NMC) was added, and in the same manner, the container was set in a planetary ball mill P-7, and mixing was continued for 5 minutes at 25 ° C. and 100 rpm, to prepare a positive electrode composition. - Preparation of a positive electrode sheet for a solid secondary battery - The positive electrode composition obtained above was applied to a 20 μm thick aluminum foil (positive electrode current collector) using a Baker applicator (trade name: SA-201, manufactured by Tester Sangyo Co., Ltd.), heated at 100 ° C. for 2 hours, and the positive electrode composition was dried (dispersion medium removed). Thereafter, using a heat press, the dried positive electrode composition was pressurized (10 MPa, 1 minute) at 25 ° C. to prepare a positive electrode sheet for an all-solid-state secondary battery having a positive electrode active material layer with a film thickness of 80 μm.

[0209] All solid state secondary batteries Nos. 116 to 128 and c201 to c206 (excluding c203) were produced in the same manner as in the production of all solid state secondary battery No. 115, except that in the production of all solid state secondary battery No. 115, negative electrode sheets for all solid state secondary batteries having a solid electrolyte layer, represented by the numbers shown in the "Electrode active material layer (sheet No.)" column in Table 5, were used instead of negative electrode sheet No. 301 for all solid state secondary batteries having a solid electrolyte layer.

[0210] <Evaluation 4: Ion Conductivity Measurement (Resistance Measurement)> The ionic conductivity of each manufactured all-solid-state secondary battery was measured. Specifically, for each all-solid-state secondary battery, AC impedance was measured at a voltage amplitude of 5 mV and a frequency of 1 MHz to 1 Hz using a 1255B FREQUENCY RESPONSE ANALYZER (trade name, manufactured by SOLARTRON) in a thermostatic bath at 25°C. The resistance in the layer thickness direction of the ion conductivity measurement sample was determined, and the ionic conductivity was calculated using the following formula (C1). The results are shown in Table 5. Formula (C1): Ion conductivity σ (mS / cm) = 1000 × sample layer thickness (cm) / [resistance (Ω) × sample area (cm)] ２ ) In formula (C1), the sample layer thickness is the value measured before placing the laminate 12 in the 2032-type coin case 11, and is the value obtained by subtracting the thickness of the current collector (total layer thickness of the solid electrolyte layer and the electrode active material layer). The sample area is the area of ​​a disk-shaped sheet with a diameter of 14.5 mm. It was determined whether the obtained ionic conductivity σ fell within any of the following evaluation criteria. In this test, an ionic conductivity σ of evaluation criterion "C" or higher is considered to be pass level. - Evaluation Criteria - A: 0.30≦σ B: 0.25≦σ<0.30 C: 0.20≦σ<0.25 D: 0.15≦σ<0.20 E: 0.10≦σ<0.15 F: σ<0.10

[0211] <Evaluation 5: High-potential cycle characteristics> The discharge capacity retention rate of each of the manufactured all-solid-state secondary batteries was measured using a charge-discharge evaluation device TOSCAT-3000 (trade name, manufactured by Toyo Systems Co., Ltd.). Specifically, each all-solid-state secondary battery was charged and discharged at a current density of 0.1 mA / cm in an environment of 25°C. ２ The battery was charged at a current density of 0.1 mA / cm until the battery voltage reached 4.5 V. ２The battery was discharged at 100°C until the battery voltage reached 2.5 V. This one charge and one discharge constituted one charge / discharge cycle, and three charge / discharge cycles were repeated under the same conditions to initialize the battery. The above charge / discharge cycles were then repeated, and the discharge capacity of each all-solid-state secondary battery was measured after each charge / discharge cycle using a charge / discharge evaluation device: TOSCAT-3000 (trade name). The high-potential cycle characteristics were evaluated based on whether the number of charge / discharge cycles at which the discharge capacity retention rate (discharge capacity relative to the initial discharge capacity) reached 80%, when the discharge capacity (initial discharge capacity) at the first charge / discharge cycle after initialization was taken as 100%, was included in the following evaluation criteria. In this test, the higher the evaluation criteria, the better the high-potential cycle characteristics, and the initial battery performance can be maintained even after multiple high-potential charge / discharge cycles (even during long-term use). In this test, a rating of "D" or higher is considered acceptable for the high-potential cycle characteristics. The results are shown in Table 5. All-solid-state secondary battery No. The initial discharge capacities of Nos. 101 to 128 all showed values ​​sufficient to function as all-solid-state secondary batteries. -Evaluation criteria- A: 600 cycles or more B: 450 cycles or more and less than 600 cycles C: 300 cycles or more and less than 450 cycles D: 150 cycles or more and less than 300 cycles E: 80 cycles or more and less than 150 cycles F: 40 cycles or more and less than 80 cycles

[0212] <Evaluation 6: Normal Potential Cycle Characteristics> The cycle characteristics at normal potential were evaluated in the same manner as in the "High Potential Cycle Characteristics" test described above in <Evaluation 5: High Potential Cycle Characteristics>, except that the potential during charging was changed to 4.3 V. The results are shown in Table 5.

[0213]

[0214] The results shown in Tables 2 to 5 reveal the following. Comparative examples of inorganic solid electrolyte-containing compositions (electrode compositions) that do not contain the polymer binder specified in the present invention are inferior in storage stability, handling properties, and adhesion, or are unable to produce all-solid-state secondary batteries with low resistance and excellent high-potential cycle characteristics. In contrast, inorganic solid electrolyte-containing compositions (electrode compositions) that contain the polymer binder specified in the present invention are excellent in dispersion stability and can strengthen the adhesion of solid particles, even at high concentrations. All-solid-state secondary batteries of the present invention that include solid electrolyte layers or active material layers formed from these compositions not only exhibit high ionic conductivity (low resistance), but also achieve excellent high-potential cycle characteristics.

[0215] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0216] This application claims priority based on Japanese Patent Application No. 2024-147109, filed on August 29, 2024, the contents of which are incorporated herein by reference as part of the present specification.

[0217] REFERENCE SIGNS LIST 1 negative electrode current collector 2 negative electrode active material layer 3 solid electrolyte layer 4 positive electrode active material layer 5 positive electrode current collector 6 operating part 10 all-solid-state secondary battery 11 2032-type coin case 12 laminate for all-solid-state secondary battery 13 coin-type all-solid-state secondary battery

Claims

1. An inorganic solid electrolyte-containing composition comprising an inorganic solid electrolyte having ionic conductivity for a metal belonging to Group 1 or 2 of the periodic table, a polymer binder, and a dispersion medium, wherein the polymer binder has a structural unit (A) derived from a disubstituted vinyl monomer having a homopolymer glass transition temperature of less than 50°C, and at least one structural unit (B) selected from a structural unit derived from styrene, a structural unit derived from a vinyl ether, and a structural unit derived from (meth)acrylamide having a homopolymer glass transition temperature of 50°C or higher, and the inorganic solid electrolyte-containing composition contains a polymer in which the total content of the structural units (A) and (B) is 80 mass% or more, and the inorganic solid electrolyte-containing composition is soluble in the dispersion medium.

2. The inorganic solid electrolyte-containing composition according to claim 1, wherein the polymer has at least one polar functional group selected from the following functional group group (a): <Functional group group (a)> sulfonic acid group, phosphoric acid group, phosphonic acid group, hydroxyl group, carboxyl group, dicarboxylic acid group, thiol group, ether group, ester group, amide group, urethane group, urea group, imide group, fluoroalkyl group, and salts thereof 3. The inorganic solid electrolyte-containing composition according to claim 1, wherein the polymer has a structural unit having at least one polar functional group selected from the following functional group group (a): <Functional group group (a)> sulfonic acid group, phosphoric acid group, phosphonic acid group, hydroxyl group, carboxyl group, dicarboxylic acid group, thiol group, ether group, ester group, amide group, urethane group, urea group, imide group, fluoroalkyl group, and salts thereof.

4. The inorganic solid electrolyte-containing composition according to claim 1, wherein the structural unit (B) includes a structural unit derived from the (meth)acrylamide.

5. The inorganic solid electrolyte-containing composition according to claim 1, wherein the glass transition temperature of the polymer is −20° C. or higher.

6. The inorganic solid electrolyte-containing composition according to claim 1, wherein the structural unit (A) comprises a structural unit derived from a 1,1-disubstituted vinyl monomer.

7. The inorganic solid electrolyte-containing composition according to claim 1, wherein the structural unit (A) includes a structural unit derived from a methacrylic acid ester monomer.

8. The inorganic solid electrolyte-containing composition according to claim 1, wherein the total content of the structural unit (A) and the structural unit (B) in the polymer is 95 mass % or more.

9. The inorganic solid electrolyte-containing composition according to claim 1, which contains an active material.

10. The inorganic solid electrolyte-containing composition according to claim 1, wherein the inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.

11. A sheet for an all-solid-state secondary battery having a layer formed using the inorganic solid electrolyte-containing composition according to any one of claims 1 to 10.

12. An all-solid-state secondary battery comprising a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order, wherein at least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is formed using the inorganic solid electrolyte-containing composition according to any one of claims 1 to 10.

13. A method for producing a sheet for an all-solid-state secondary battery, comprising forming a film from the inorganic solid electrolyte-containing composition according to any one of claims 1 to 10.

14. A method for producing an all-solid-state secondary battery, comprising the steps of: producing an all-solid-state secondary battery through the method according to claim 13;

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