Electrode composition, all-solid-state secondary battery electrode sheet, all-solid-state secondary battery, production method for all-solid-state secondary battery electrode sheet, and production method for all-solid-state secondary battery

Abstract

Provided are an electrode composition, an all-solid-state secondary battery electrode sheet and an all-solid-state secondary battery containing the electrode composition, and production methods for an all-solid-state secondary battery electrode sheet and an all-solid-state secondary battery. The electrode composition contains a dispersion medium, and contains 10-35% by mass of an inorganic solid electrolyte, 60-88% by mass of an electrode active material, 0.1-5% by mass of a conductive additive, and 0.2-5% by mass of a binder with respect to 100% by mass of solid components. The binder contains a polymer binder that is composed of a polymer containing 30-99.9% by mass of a constituent unit represented by a specific formula and that dissolves in the dispersion medium. The polymer binder has a 180° peel strength of 250 N / m or greater between the polymer binder and a current collector.

Description

Electrode composition, electrode sheet for all-solid-state secondary battery, and all-solid-state secondary battery, as well as a method for manufacturing an electrode sheet for an all-solid-state secondary battery and a method for manufacturing an all-solid-state secondary battery.

[0001] The present invention relates to an electrode composition, an electrode sheet for an all-solid-state secondary battery, and an all-solid-state secondary battery, as well as a method for manufacturing an electrode sheet for an all-solid-state secondary battery and a method for manufacturing an all-solid-state secondary battery.

[0002] All-solid-state rechargeable batteries consist entirely of solid negative electrodes, electrolytes, and positive electrodes, significantly improving the safety and reliability issues associated with batteries using organic electrolytes. They are also expected to offer longer lifespans. Furthermore, all-solid-state rechargeable batteries can be constructed with electrodes and electrolytes directly arranged in series. Therefore, they enable higher energy density compared to rechargeable batteries using organic electrolytes, and are expected to have applications in electric vehicles and large-scale storage batteries.

[0003] In all-solid-state secondary batteries, the constituent layers (solid electrolyte layer, negative electrode active material layer, positive electrode active material layer, etc.) are usually formed as layers of solid particles using a slurry composition (constituent layer forming material) in which solid particles such as inorganic solid electrolyte, active material, and conductive additive are dispersed in a dispersion medium. However, if solid particles are localized or aggregated within the constituent layer, resulting in a non-uniform state (uneven distribution), current concentration and / or ion concentration occur locally in the inorganic solid electrolyte and / or active material during charging and discharging, making the inorganic solid electrolyte and / or active material more susceptible to degradation. As a result, this leads to a decrease in battery performance (also called battery characteristics), such as charge / discharge characteristics and life characteristics. Therefore, various constituent layer forming materials have been proposed that improve the dispersibility of solid particles by mixing a binder containing a polymer with the solid particles. For example, Patent Document 1 describes the electrode composition shown below. According to Patent Document 1, the following electrode composition exhibits excellent dispersion stability even when the solid content concentration is increased, and when used as an active material layer forming material for all-solid-state secondary batteries, it is possible to suppress the increase in battery resistance and achieve excellent cycle characteristics. "An electrode composition containing an inorganic solid electrolyte (SE) having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, an active material (AC), a conductive additive (CA), a polymer binder (B), and a dispersion medium (D), and satisfying the following conditions (1) to (4): (1) The polymer binder (B) is dissolved in the dispersion medium (D) (2) The adsorption rate of the polymer binder (B) to the conductive additive (CA) in the dispersion medium (D) [A ＣＡ (3) The mass-average molecular weight of the polymer constituting the polymer binder (B) is 6,000 or more. (4) The average particle size of the conductive additive (CA) present in the active material layer formed with the electrode composition is less than 1.0 μm.

[0004] Furthermore, Patent Document 2 describes the following inorganic solid electrolyte-containing composition. According to Patent Document 2, the following inorganic solid electrolyte-containing composition exhibits excellent dispersion stability and handling properties. "An inorganic solid electrolyte-containing composition comprising an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a polymer binder, and a dispersion medium, wherein the polymer binder comprises a polymer binder made of a styrene-ethylene-butylene-styrene copolymer having a styrene component content greater than 0 mol% and less than 50 mol%, and the SP value of the dispersion medium is 15 to 21 MPa １／２ "An inorganic solid electrolyte-containing composition wherein the adsorption rate of the polymer binder, which is made of the copolymer, to the inorganic solid electrolyte in the dispersion medium is less than 60%."

[0005] International Publication No. 2023 / 282333, International Publication No. 2021 / 039949

[0006] In materials forming constituent layers, development of high-concentration compositions (concentrated slurries) with increased solid content is progressing, with the aim of improving the dispersibility of solid particles while also considering recent trends such as reducing environmental impact, improving manufacturability or reducing manufacturing costs, and enabling thicker constituent layers. However, as the solid content concentration of the constituent layer forming material increases, the dispersibility of solid particles and binders deteriorates significantly. As a result, solid particles and binders become localized within the constituent layer, and the surface flatness of the constituent layer also tends to decrease. This leads to a decrease in battery performance. Therefore, constituent layer forming materials are required to exhibit excellent dispersibility of each component, such as solid particles and binders, even at high concentrations.

[0007] On the other hand, with the recent advancements in the performance and practical application of electric vehicles, there is a growing demand for higher performance in all-solid-state secondary batteries. For example, improving the energy density of all-solid-state secondary batteries is being considered. One effective way to improve energy density is to increase the thickness of the active material layer. However, when attempting to increase the thickness of the active material layer of the electrode sheet, the active material layer tends to peel off from the current collector, and parts of the active material layer are prone to being lost. From the standpoint of productivity and industrial manufacturing, all-solid-state secondary batteries are typically manufactured by laminating the active material layer with a current collector to create the electrode sheet, which is then used in the production of the all-solid-state secondary battery. For example, one method involves continuously supplying (transporting) a long current collector (base sheet) wound on a roll to a production line, forming an active material layer on the current collector, and then manufacturing the electrode sheet using a continuous manufacturing method such as the roll-to-roll method, which winds the resulting electrode sheet into a roll. This electrode sheet is then used in the production of the all-solid-state secondary battery. Therefore, when attempting to increase the thickness of the active material layer of an electrode sheet, problems such as delamination of the active material layer from the current collector and partial loss of the active material layer (reduced handling) become particularly pronounced in continuous manufacturing methods such as the roll-to-roll method, which are widely used as industrial manufacturing methods. When such handling problems occur, it leads to a decrease in productivity, and in particular, it undermines the advantages of continuous manufacturing methods that can achieve high productivity. Moreover, if the active material layer is made from a high-concentration composition, the deterioration of the dispersibility of the high-concentration composition leads to a further decrease in handling. However, in Patent Documents 1 and 2, in addition to resolving the problem by increasing the concentration of the constituent layer forming material, the problem of thickening the active material layer and the resulting decrease in handling has not been considered.

[0008] The present invention aims to provide an electrode composition that exhibits excellent dispersibility even when the solid content concentration is increased, and which, when used as a material for forming an active material layer (electrode sheet for all-solid-state secondary batteries) on the surface of a current collector, achieves excellent handling even when the active material layer is made thick. Furthermore, the present invention aims to provide an electrode sheet for all-solid-state secondary batteries and an all-solid-state secondary battery using this electrode composition, as well as a method for manufacturing an electrode sheet for an all-solid-state secondary battery and a method for manufacturing an all-solid-state secondary battery.

[0009] The inventors of the present invention have diligently studied electrode compositions for forming the active material layer of all-solid-state secondary batteries, aiming to solve both problems: deterioration of dispersibility due to high concentration of solid components and decreased handling performance due to thicker active material layers. They discovered that by setting the content of each component in the electrode composition within a specific range and by making the polymer binder used as a binder soluble in the dispersion medium, the binder itself disperses well even when the electrode composition is highly concentrated, thereby improving the dispersibility of solid particles. Furthermore, since the breakdown of the active material layer due to external stress etc. is more likely to occur on the current collector side and causes the aforementioned decrease in handling performance, in addition to the conventional development trend of focusing on strengthening the adhesion force between solid particles to suppress the breakdown of the active material layer, the inventors have also focused on strengthening the adhesion force of the polymer binder itself to the current collector, and have proceeded with the study of a binder that can strengthen both adhesion forces in a balanced manner. As a result, we discovered that by using a polymer that incorporates a specific structural unit represented by a specific formula into its molecule at a specific content and exhibits a specific peel strength against the current collector, as a binder used in combination with the components constituting the electrode composition, it is possible to realize an active material layer that adheres firmly to the current collector even when thickened, while maintaining the above-mentioned dispersibility-improving effect in the electrode composition, thereby solving both of the above problems at once. This invention was completed after further investigation based on these findings.

[0010] In other words, the above problems were solved by the following means: <1> An electrode composition comprising an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, an electrode active material, a conductive additive, a binder, and a dispersion medium, wherein the inorganic solid electrolyte accounts for 10 to 35% by mass, the electrode active material accounts for 60 to 88% by mass, the conductive additive accounts for 0.1 to 5% by mass, and the binder accounts for 0.2 to 5% by mass, and the binder consists of a polymer containing 30 to 99.9% by mass of constituent units represented by the following formula A, and includes a polymer binder that dissolves in the dispersion medium, wherein the polymer binder has a 180° peel strength with respect to a current collector of 250 N / m or more. In equation A, R１ represents a hydrogen atom or a methyl group, and R ２ represents an alkyl group having 6 to 24 carbon atoms or a group containing a siloxane bond.

[0011] <2> The electrode composition according to <1>, wherein the polymer contains 30 to 99.9% by mass of a structural unit represented by Formula A, and contains 0.1 to 65% by mass of at least one selected from a structural unit represented by the following Formula B, a structural unit represented by the following Formula C and a structural unit represented by the following Formula D. In Formula B, R ３ represents a hydrogen atom or a methyl group, and R ４ and R ５ each represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and R ４ and R ５ may be bonded to each other. In Formula C, R ６ and R ７ each represent a hydrogen atom or a methyl group, R ８ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, R ９ and R １０ each represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and R ９ and R １０ may be bonded to each other. In Formula D, R １１ and R １２ each represent a hydrogen atom or a methyl group, and R １３ represents a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, or a phenyl group. <3> The electrode composition according to <1> or <2>, wherein an adsorption rate A ＳＥ of the polymer binder to the inorganic solid electrolyte in a dispersion medium is more than 4% and 45% or less. ＳＥ The electrode composition according to any one of <1> to <4>, wherein the 180° peel strength is 350 N / m or more. The electrode composition according to any one of <1> to <4>, wherein the adsorption rate A is more than 15% and 40% or less. The electrode composition according to any one of <1> to <5>, wherein the polymer contains 30 to 82% by mass of a structural unit represented by the following Formula A1, and contains 18 to 45% by mass of a structural unit represented by the following Formula B. In Formula A1, R １ represents a hydrogen atom or a methyl group, and R ２R represents an alkyl group having 6 to 24 carbon atoms. In formula B, R ３ R represents a hydrogen atom or a methyl group. ４ and R ５ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ４ and R ５ The polymer may be bonded. <7> The electrode composition according to any one of <1> to <5>, wherein the polymer contains 45 to 99% by mass of a constituent unit represented by the following formula A2 and 1 to 50% by mass of a constituent unit represented by the following formula B. In equation A2, R １ R represents a hydrogen atom or a methyl group. ２ R indicates a group containing a siloxane bond. In formula B, R ３ R represents a hydrogen atom or a methyl group. ４ and R ５ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ４ and R ５ The polymer may be bonded. <8> The electrode composition according to any one of <1> to <5>, wherein the polymer contains 50 to 99.5% by mass of a constituent unit represented by the following formula A, and contains 0.5 to 40% by mass of at least one of a constituent unit represented by the following formula C and a constituent unit represented by the following formula D. In equation A, R １ R represents a hydrogen atom or a methyl group. ２ R represents an alkyl group having 6 to 24 carbon atoms, or a group containing a siloxane bond. In formula C, R ６ and R ７ R represents a hydrogen atom or a methyl group. ８ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ９ and R １０ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ９ and R １０ They may be combined. In equation D, R １１ and R １２ R represents a hydrogen atom or a methyl group. １３<1> represents a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, or a phenyl group. <9> An electrode sheet for an all-solid-state secondary battery having an electrode active material layer composed of the electrode composition described in any one of <1> to <8> above. <10> 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 and the negative electrode active material layer is a layer formed using the electrode composition described in any one of <1> to <8> above. <11> A method for manufacturing an electrode sheet for an all-solid-state secondary battery, comprising forming a film of the electrode composition described in any one of <1> to <8> above. <12> A method for manufacturing an all-solid-state secondary battery, comprising manufacturing an all-solid-state secondary battery via the manufacturing method described in <11> above.

[0012] The present invention provides an electrode composition that exhibits excellent dispersibility even when the solid content concentration is increased, and by using it as a material for forming an active material layer (electrode sheet for all-solid-state secondary batteries) on the surface of a current collector, it is possible to provide an electrode composition that achieves excellent handling even when the active material layer is made thick. Furthermore, the present invention can provide an electrode sheet for all-solid-state secondary batteries and an all-solid-state secondary battery using this electrode composition, as well as a method for manufacturing an electrode sheet for an all-solid-state secondary battery and a method for manufacturing an all-solid-state secondary battery. The above and other features and advantages of the present invention will become clearer from the following description with reference to the attached drawings as appropriate.

[0013] Figure 1 is a schematic longitudinal cross-sectional view showing an all-solid-state secondary battery according to a preferred embodiment of the present invention. Figure 2 is a schematic longitudinal cross-sectional view showing a coin-type all-solid-state secondary battery fabricated in the example.

[0014] In the present invention, when describing the content, physical properties, etc., of components by indicating numerical ranges, if the upper and lower limits of the numerical range are described separately, either upper or lower limit can be appropriately combined to form a specific numerical range. On the other hand, when multiple numerical ranges represented by "~" are set and described, the upper and lower limits that form the numerical range are not limited to the specific combination of upper and lower limits written before and after "~" as a specific numerical range, but can be a numerical range formed by appropriately combining the upper and lower limits of each numerical range. In the present invention, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits.

[0015] In this invention, the designation of a compound (for example, when referred to as a compound) includes not only the compound itself, but also its salts and ions. It also includes derivatives in which a part of the compound has been altered, such as by introducing substituents, to the extent that it does not impair the effects of this invention. In this invention, substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) that are not specified as substituted or unsubstituted mean that the group may have appropriate substituents. Therefore, in this invention, even when simply referred to as a YYY group, this YYY group includes not only the unsubstituted form but also the form with substituents. This is also true for compounds that are not specified as substituted or unsubstituted. A preferred substituent is, for example, substituent Z, which will be described later. In this invention, when there are multiple substituents, etc. indicated by a specific symbol, or when multiple substituents, etc. are specified simultaneously, it means that each substituent, etc. may be the same as or different from the others. Also, even if not specifically stated, when multiple substituents, etc. are adjacent, they may be linked to each other or fused to form a ring. In this invention, (meth)acrylic means either or both of acrylic and methacrylic. The same applies to (meth)acrylates.

[0016] In this invention, the binder (sometimes referred to as "binder") is specified for convenience, focusing on its function in the active material layer, and does not need to have binding properties as long as it achieves the effects of the present invention. For example, it can also be called a "dispersant" when focusing on its function in the electrode composition. In this invention, polymer means polymer, but is synonymous with so-called high-molecular-weight compound. In this invention, the main chain of a polymer refers to linear molecular chains in which all other molecular chains constituting the polymer can be considered as branched chains or pendant groups relative to the main chain. Although it depends on the weight-average molecular weight of the molecular chains considered as branched chains or pendant chains, typically the longest chain among the molecular chains constituting the polymer becomes the main chain. However, the end groups of the polymer ends are not included in the main chain. In contrast, the side chains of a polymer refer to molecular chains other than the main chain, and include short chains and long chains (graft chains). The end groups of the polymer are not particularly limited and can take on appropriate groups depending on the polymerization method, etc. Examples of terminal groups include hydrogen atoms, alkyl groups, aryl groups, hydroxyl groups, and residues such as polymerization initiators.

[0017] 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 electrode active material layer, and 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 electrode active material.

[0018] [Electrode Composition] The electrode composition of the present invention contains an inorganic solid electrolyte having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, an electrode active material, a conductive additive, a binder, and a dispersion medium, in specific amounts. Specifically, the inorganic solid electrolyte accounts for 10 to 35% by mass of 100% by mass of the solid content of the electrode composition, the electrode active material accounts for 60 to 88% by mass, the conductive additive accounts for 0.1 to 5% by mass, and the binder accounts for 0.2 to 5% by mass. Furthermore, the binder consists of a polymer containing 30 to 99.9% by mass of a constituent unit represented by formula A described later, and includes a polymer binder that dissolves in the dispersion medium. This polymer binder exhibits a 180° peel strength of 250 N / m or more when a binder layer formed with the polymer binder is bonded to a current collector.

[0019] Such electrode compositions allow for good dispersion of solid particles in the dispersion medium (electrode composition) by ensuring that the binder is well dispersed, preferably uniformly. The binder's ability to improve the dispersibility of solid particles is maintained even when the electrode composition is highly concentrated (high solid differentiation). In other words, the binder can be highly concentrated in the electrode composition while maintaining good dispersibility. As a result, the electrode active material layer formed with this electrode composition exists in a state where the binder and solid particles are well dispersed, preferably uniformly dispersed. Therefore, when the active material layer is formed on a current collector, segregation can be suppressed, allowing the binder to be present near the interface with the current collector, resulting in adhesion to the current collector in addition to adhesion to the solid particles. Furthermore, since the segregation of the binder and solid particles is suppressed, the active material layer is preferably considered to have a flat surface. Furthermore, if the binder contains the above-mentioned polymer binder, it is thought that it can exhibit good adsorption (adhesion) to solid particles while also exhibiting adhesion to the current collector, thereby strengthening both adhesions in a balanced manner. This allows the electrode composition to maintain its excellent dispersibility even at high concentrations, and enables the formation of an active material layer that adheres firmly to the current collector even when the film is thick.

[0020] By using the electrode composition of the present invention as a material for forming the active material layer (active material layer forming material), it is possible to manufacture an electrode sheet for all-solid-state secondary batteries that exhibits excellent handling properties even when made into a thick film. Furthermore, an all-solid-state secondary battery containing this electrode sheet exhibits excellent cycle characteristics and can also improve energy density.

[0021] The electrode composition of the present invention, with its increased solid content concentration, enables the efficient production of a thickened active material layer with high handling efficiency in the manufacture of electrode sheets for all-solid-state secondary batteries. Furthermore, the electrode composition of the present invention, with its increased solid content concentration, can be applied to continuous manufacturing methods such as the roll-to-roll method, which are widely used as industrial manufacturing methods for electrode sheets for all-solid-state secondary batteries. The electrode composition of the present invention, with its increased solid content concentration, offers manufacturing advantages (manufacturability) such as reduced environmental impact due to shorter drying times and reduced dispersant evaporation, as well as reduced manufacturing costs.

[0022] In the electrode composition of the present invention, the binder, particularly the polymer binder, is thought to exhibit the function of dispersing the solid particles in the dispersion medium by adsorbing onto solid particles and interposing between them. Here, the adsorption of the binder, particularly the polymer binder, onto 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 dispersibility of solid particles by the binder, particularly the polymer binder, is exhibited even when the solid content concentration is increased. Thus, the polymer binder of the present invention enables high solid content differentiation of the electrode composition. On the other hand, in the active material layer, the binder, particularly the polymer binder, exhibits the function of a binder that binds solid particles together, and also exhibits the function of a binder that binds the current collector to the solid particles. In the electrode composition, the polymer binder may or may not have the function of binding solid particles together.

[0023] The electrode composition of the present invention is an electrode composition for manufacturing all-solid-state secondary batteries (active material layer formation). In particular, a positive electrode composition for forming a positive electrode in which a current collector and a positive electrode active material layer are laminated is preferable in that it contributes to improving the energy density of the all-solid-state secondary battery. Therefore, the electrode composition of the present invention can be preferably used as a material for forming electrode sheets for all-solid-state secondary batteries (preferably positive electrode sheets for all-solid-state secondary batteries) and active material layers for all-solid-state secondary batteries (preferably positive electrode active material layers).

[0024] The electrode composition of the present invention containing the above components in the above-mentioned amounts exhibits excellent dispersibility, and more preferably exhibits low viscosity at 25°C in terms of handling ease and electrode active material layer formation. For example, the viscosity (at 25°C, shear rate 10 / s) in the examples described later is preferably 3500 cP or less, and more preferably 100 to 2000 cP or less.

[0025] The electrode composition of the present invention is preferably a non-aqueous composition. In the present invention, a non-aqueous composition includes not only a form that does not contain water, but also a form in which the water content (also called 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 electrode composition is a non-aqueous composition, the deterioration of the inorganic solid electrolyte can be suppressed. The water content indicates the amount of water contained in the electrode composition (mass ratio to the electrode composition), and specifically, it is the value measured by filtering with a 0.02 μm membrane filter and using Karl Fischer titration.

[0026] The electrode composition of the present invention will now be described. The electrode composition of the present invention contains an inorganic solid electrolyte, an electrode active material, a conductive additive, a binder, and a dispersion medium in the following proportions. That is, the content of the inorganic solid electrolyte relative to 100% by mass of the solid content of the electrode composition is 10 to 35% by mass. When the content of the inorganic solid electrolyte is within this range, the overall dispersibility of the solid particles can be improved even when the concentration is increased, and the binder, in particular the polymer binder used in the present invention (hereinafter, "binder" is synonymous), which will be described later, can also be present on the current collector side in the active material layer which exhibits excellent ionic conductivity. The above content of the inorganic solid electrolyte is preferably 10 to 30% by mass, and more preferably 10 to 25% by mass, in order to achieve a high level of balance between the overall dispersibility of the solid particles and the handling properties of the electrode sheet for all-solid-state secondary batteries, thereby realizing an all-solid-state secondary battery with excellent cycle characteristics and high energy density.

[0027] The content of the electrode active material relative to 100% by mass of the solid content of the electrode composition is 60 to 88% by mass. When the content of the electrode active material is within this range, the overall dispersibility of the solid particles can be improved even at high concentrations, and an active material layer exhibiting excellent capacitance can be formed. The above content of the electrode active material is preferably 72 to 88% by mass, and more preferably 75 to 87% by mass, in order to achieve a high level of both overall dispersibility of the solid particles and capacitance. The content of the positive electrode active material relative to 100% by mass of the solid content of the electrode composition can be appropriately determined within the above range of the content of the electrode active material, and is preferably the same as the above content of the electrode active material. On the other hand, the content of the negative electrode active material relative to 100% by mass of the solid content of the electrode composition can be appropriately determined considering the content of the electrode active material, and for example, it is preferably 60 to 80% by mass, more preferably 60 to 75% by mass, and even more preferably 65 to 75% by mass, in that it is possible to achieve a high level of both the overall dispersibility of the solid particles and the capacitance.

[0028] The total content of inorganic solid electrolyte and electrode active material relative to 100% by mass of solid content in the electrode composition can be appropriately determined considering the above individual content. The total content of inorganic solid electrolyte and electrode active material is preferably 70 to 99.5% by mass, more preferably 90 to 99% by mass, and even more preferably 93 to 98% by mass, in order to achieve a good balance between the overall dispersibility of solid particles, the handling of the electrode sheet for all-solid-state secondary batteries, and the ionic conductivity and electronic conductivity of the active material layer. The ratio of the content of inorganic solid electrolyte to the content of electrode active material [content of inorganic solid electrolyte: content of electrode active material] in 100% by mass of solid content in the electrode composition is not particularly limited, but for example, it is preferably 1:1 to 1:8.8, more preferably 1:1 to 1:8.7, and even more preferably 1:1.2 to 1:8.6.

[0029] The content of the conductive additive relative to 100% by mass of the solid content of the electrode composition is 0.1 to 5% by mass. When the content of the conductive additive is within this range, the overall dispersibility of the solid particles can be improved even at high concentrations, and an active material layer exhibiting excellent electronic conductivity can be formed. The above content of the conductive additive is preferably 0.1 to 4.5% by mass, more preferably 0.1 to 4% by mass, and even more preferably 0.5 to 4% by mass, in order to achieve a high level of both overall dispersibility of the solid particles and electronic conductivity.

[0030] The binder content relative to 100% by mass of the solid content of the electrode composition is 0.2 to 5% by mass. When the binder content is within this range, the overall dispersibility of the solid particles can be improved even at high concentrations, and the binder can also be dispersed on the current collector side within the active material layer. The binder content is preferably 0.3 to 4.5% by mass, more preferably 0.5 to 4% by mass, and even more preferably 0.5 to 3% by mass, in order to achieve a high level of balance between the overall dispersibility of the solid particles and the handling properties of the electrode sheet for all-solid-state secondary batteries, thereby realizing an all-solid-state secondary battery with excellent cycle characteristics and high energy density. In the electrode composition of the present invention, in 100% by mass of solid content, the mass ratio of the total content of inorganic solid electrolyte and electrode active material to the content of binder [(mass of inorganic solid electrolyte + total content of active material) / (content of binder)] is preferably 1000 to 5, more preferably 500 to 7, even more preferably 300 to 10, and still more preferably 200 to 10.

[0031] The solid content concentration in the electrode composition of the present invention is not particularly limited, and is usually 20 to 92% by mass at 25°C, preferably 30 to 88% by mass, and more preferably 45 to 85% by mass. On the other hand, the electrode composition of the present invention can also be a high-concentration composition with a higher solid content concentration than conventional compositions. For example, the lower limit of the solid content concentration of the high-concentration composition can be set to 50% by mass or more at 25°C, for example, 60% by mass or more. The upper limit is less than 100% by mass, for example, 95% by mass or less, preferably 92% by mass or less, more preferably 90% by mass or less, and even more preferably 88% by mass or less. In the present invention, solid content (solid components) refers to components that do not volatilize or evaporate when the electrode composition is dried at 150°C for 6 hours under a pressure of 1 mmHg and a nitrogen atmosphere. Typically, it refers to components other than the dispersion medium described later.

[0032] The content of the dispersion medium in the electrode composition is not particularly limited, but is set within a range that satisfies the above-mentioned solid content concentration.

[0033] If the electrode composition contains two or more of each component, the content of each component shall be the total content. The content of other components that the electrode composition may contain will be described later.

[0034] [Inorganic Solid Electrolyte] The electrode composition of the present invention contains an inorganic solid electrolyte. In the present invention, an inorganic solid electrolyte is an inorganic solid electrolyte, and a solid electrolyte is a solid electrolyte that can move ions within itself. Since it does not contain organic substances as the main ion-conducting material, it is clearly distinguished from organic solid electrolytes (polymer electrolytes such as polyethylene oxide (PEO), and organic electrolyte salts such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)). Furthermore, since inorganic solid electrolytes are solid in a steady state, they do not normally dissociate or become liberated into cations and anions. In this respect, inorganic electrolyte salts (LiPF) that dissociate or become liberated into cations and anions in the electrolyte or polymer are clearly distinguished from inorganic electrolyte salts (LiPFSI) that dissociate or become liberated into cations and anions in the electrolyte or polymer. ６ LiBF ４ It is also clearly distinguished from lithium bis(fluorosulfonyl)imide (LiFSI), LiCl, etc. Inorganic solid electrolytes are not particularly limited as long as they have conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, and generally do not have electronic conductivity.

[0035] The inorganic solid electrolyte described above can be appropriately selected from solid electrolytes commonly used in all-solid-state secondary batteries. For example, 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. From the viewpoint of forming a better interface between the active material and the inorganic solid electrolyte and effectively suppressing the increase in interfacial resistance, sulfide-based inorganic solid electrolytes are preferred. When the all-solid-state secondary battery of the present invention is a lithium-ion battery, the inorganic solid electrolyte preferably has lithium ion conductivity.

[0036] (i) Sulfide-based inorganic solid electrolytes The sulfide-based inorganic solid electrolytes preferably contain sulfur atoms, have ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and have electronic insulating properties. The sulfide-based inorganic solid electrolytes preferably contain at least Li, S, and P as elements and have lithium ion conductivity, but may optionally contain other elements other than Li, S, and P.

[0037] Examples of sulfide-based inorganic solid electrolytes include lithium-ion conductive inorganic solid electrolytes that satisfy the composition shown in 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, with Li being preferred. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. A represents an element selected from I, Br, Cl, and F. a1 to e1 represent the composition ratio of each element, where a1:b1:c1:d1:e1 satisfies 1 to 12:0 to 5:1:2 to 12:0 to 10. a1 is preferably 1 to 9, more preferably 1.5 to 7.5. b1 is preferably 0 to 3, more preferably 0 to 1. d1 is preferably 2.5 to 10, more preferably 3.0 to 8.5. e1 is preferably 0 to 5, more preferably 0 to 3.

[0038] The composition ratio of each element can be controlled by adjusting the amount of raw material compounds used when producing sulfide-based inorganic solid electrolytes, as shown below.

[0039] The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystalline (glass-ceramic), or partially crystalline. For example, Li-P-S glass containing Li, P, and S, or Li-P-S glass-ceramic containing Li, P, and S can be used. The sulfide-based inorganic solid electrolyte is, for example, lithium sulfide (Li ２ S), phosphorus sulfide (for example, 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 element represented by M above (e.g., SiS ２ , SnS, GeS ２ ) can be produced by reacting at least two or more of the raw materials.

[0040] In Li-P-S-based glass and Li-P-S-based glass-ceramics, the ratio of Li ２ S to P ２ S ５ in terms of molar ratio of Li ２ S: P ２ S ５ is preferably 60:40 to 90:10, more preferably 68:32 to 78:22. By setting the ratio of Li ２ S to P ２ S ５ within this range, high lithium ion conductivity can be achieved. Specifically, the lithium ion conductivity can be preferably 1×10 －４ S / cm or more, more preferably 1×10 －３ S / cm or more. There is no particular upper limit, but it is practically 1×10 －１ S / cm or less.

[0041] Examples of combinations of raw materials are shown below as specific examples of sulfide-based inorganic solid electrolytes. 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 PO ４ Li １０ GeP ２ S １２ These are some examples. However, the mixing ratio of each raw material is not specified. As a method for synthesizing sulfide-based inorganic solid electrolytes using such raw material compositions, one example is the amorphous method. Examples of amorphous methods include the mechanical milling method, the solution method, and the melt-quenching method. This is because processing at room temperature is possible, and the manufacturing process can be simplified.

[0042] (ii) Oxide-based inorganic solid electrolytes are preferably oxide-based inorganic solid electrolytes that contain oxygen atoms, have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and have electronic insulating properties. The oxide-based inorganic solid electrolyte has an ionic conductivity of 1 × 10⁻¹⁰. －６ It is preferable that the S / cm is greater than or equal to 5 × 10 －６ It is more preferable that the S / cm or higher is 1 × 10 －５ It is particularly preferable that the ratio be 1 / cm or higher. There is no particular upper limit, but 1 × 10 －１ It is practical for the ratio to be less than or equal to S / cm.

[0043] Specific examples of compounds include, for example, 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, M ｅｅ D 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 O-B２ O ３ -P ２ O ５ Li ２ O-SiO ２ Li ６ BaLa ２ Ta ２ O １２ Li ３ PO （４－３／２ｗ） N ｗ (where 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 (Natrium 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 Examples include (LLZ). Phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li ３ PO ４ LiPON; LiPOD １ (D １ The element 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. Other examples include LiA. １ ON (A １ (This is one or more elements selected from Si, B, Ge, Al, C, and Ga.) Other elements such as () can also be preferably used.

[0044] (iii) Halide-based inorganic solid electrolytes The halide-based inorganic solid electrolyte is preferably a compound that contains halogen atoms, has conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, and has electronic insulating properties. The halide-based inorganic solid electrolyte is not particularly limited, but for example, LiCl, LiBr, LiI, and Li as described in ADVANCED MATERIALS, 2018, 30, 1803075 ３ YBr ６ Li ３ YCl ６ Examples of such compounds include Li ３ YBr ６ Li ３ YCl ６ It is preferable.

[0045] (iv) Hydride-based inorganic solid electrolytes are preferably compounds that contain hydrogen atoms, have ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and have electronic insulating properties. There are no particular limitations on the hydride-based inorganic solid electrolyte, but for example, LiBH ４ Li ４ (BH ４ ) ３ I, 3LiBH ４ - Examples include LiCl, etc.

[0046] Inorganic solid electrolytes are preferably in particulate form in the electrode composition. In the present invention, when a specific component is in particulate form, the shape of the particles is not particularly limited and may be flattened, amorphous, etc., but spherical or granular is preferred. When the inorganic solid electrolyte is in particulate form, the particle diameter (volume average particle diameter) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or larger, more preferably 0.1 μm or larger, and more preferably 0.5 μm or larger. As an upper limit, it is preferably 100 μm or less, more preferably 50 μm or less, and more preferably 20 μm or less. In particular, when the particle diameter of the inorganic solid electrolyte is in the range of 0.3 to 15 μm, the dispersibility and handling of the electrode composition are excellent. The particle diameter of the inorganic solid electrolyte is measured by the following procedure. Dilute the particles of the inorganic solid electrolyte with water (heptane in the case of a substance unstable in water) in a 20 mL sample bottle to prepare a 1% by 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 laser diffraction / scattering particle size distribution analyzer LA-920 (product name, manufactured by HORIBA Corporation) at a temperature of 25°C using a quartz cell to obtain the volume-average particle size. For other detailed conditions, refer to the description in Japanese Industrial Standard (JIS) Z 8828:2013 "Particle size analysis - Dynamic light scattering method" as needed. Five samples are prepared for each level and their average value is adopted.

[0047] The method for adjusting the particle size is not particularly limited, and known methods can be applied, such as using a conventional grinder or classifier. Suitable grinders or classifiers include, for example, mortars, ball mills, sand mills, vibrating ball mills, satellite ball mills, planetary ball mills, swirling airflow jet mills, or sieves. Wet grinding can be performed with a dispersion medium such as water or methanol present during grinding. Classification is preferable to obtain the desired particle size. Classification is not particularly limited and can be performed using sieves, wind classifiers, etc. Classification can be performed both dry and wet.

[0048] The electrode composition may contain one or more types of inorganic solid electrolytes.

[0049] [Electrode Active Material] The electrode composition of the present invention contains an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the periodic table. Examples of active materials include positive electrode active materials and negative electrode active materials, which will be described below. As the electrode active material used in the electrode composition of the present invention, a positive electrode active material is preferred in that it contributes to increasing the energy density of all-solid-state secondary batteries.

[0050] <Positive Electrode Active Material> The positive electrode active material is an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the periodic table, and is preferably capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above characteristics, and may be a transition metal oxide, or an organic substance, sulfur, or other element that can be compounded with Li. Among these, it is preferable to use a transition metal oxide as the positive electrode active material, and a transition metal element M ａ A transition metal oxide having one or more elements selected from Co, Ni, Fe, Mn, Cu, and V is more preferable. ｂ Other elements of the periodic table of metals, such as elements from Group 1 (Ia), Group 2 (IIa), Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B, may be mixed. The amount of the transition metal element M may be used. ａ Li / M ａ A more preferable product is one synthesized by mixing the elements so that the molar ratio is 0.3 to 2.2. Specific examples of transition metal oxides include (MA) transition metal oxides having a layered rock salt structure, (MB) transition metal oxides having a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD) lithium-containing transition metal halogenated phosphate compounds, and (ME) lithium-containing transition metal silicate compounds.

[0051] (MA) As a specific example of a transition metal oxide having a layered rock salt structure, LiCoO ２ (Lithium cobalt oxide [LCO]), LiNi ２ O ２ (Lithium nickelate), LiNi ０．８５ Co ０．１０ Al ０．０５ O２ (Lithium nickel-cobalt aluminate [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 nickelate) is one example. (MB) LiMn is a specific example of a transition metal oxide having a spinel-type structure. ２ O ４ (LMO), LiCoMnO ４ Li ２ FeMn ３ O ８ Li ２ CuMn ３ O ８ Li ２ CrMn ３ O ８ and Li ２ NiMn ３ O ８ Examples include (MC) lithium-containing transition metal phosphate compounds, such as LiFePO ４ and Li ３ Fe ２ (PO ４ ) ３ Olivine-type iron phosphates such as LiFeP ２ O ７ Iron pyrophosphates such as LiCoPO ４ Cobalt phosphates such as Li ３ V ２ (PO ４ ) ３ Examples include monoclinic vanadium phosphate salts such as (lithium vanadium phosphate). Examples of (MD) lithium-containing transition metal halide phosphate compounds include Li ２ FePO ４ F, etc., iron fluoride phosphate, Li ２ MnPO ４ F and other manganese phosphate fluorides and Li ２ CoPO ４ Examples include cobalt fluoride phosphates such as F. (ME) Examples of lithium-containing transition metal silicate compounds include Li ２FeSiO ４ Li ２ MnSiO ４ Li ２ CoSiO ４ Examples include the above. In the present invention, transition metal oxides having a (MA) layered rock salt type structure are preferred, and LCO or NMC are more preferred.

[0052] The shape of the positive electrode active material is not particularly limited, but it is preferably particulate in the electrode 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, and preferably 0.5 to 20 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 also the same as the method for measuring 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.

[0053] The electrode composition may contain one or more types of positive electrode active materials.

[0054] <Negative Electrode Active Material> The negative electrode active material is an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the periodic table, and is preferably capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above characteristics, and examples include carbonaceous materials, metal oxides, metal composite oxides, elemental lithium, lithium alloys, and negative electrode active materials that can form alloys with lithium (can be alloyed). Among these, carbonaceous materials, metal composite oxides, or elemental lithium are preferred from the viewpoint of reliability. Active materials that can be alloyed with lithium are preferred in that they enable the production of high-capacity all-solid-state secondary batteries.

[0055] Carbonaceous materials used as negative electrode active materials are materials that consist substantially of carbon. Examples include petroleum pitch, carbon black such as acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor-grown graphite, etc.), and carbonaceous materials obtained by firing various synthetic resins such as PAN (polyacrylonitrile) resins or furfuryl alcohol resins. Furthermore, examples include various types of 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 plate-shaped graphite. These carbonaceous materials can also be divided into hard carbonaceous materials (also called hard carbon) and graphitic carbonaceous materials depending on the degree of graphitization. Furthermore, the carbonaceous material preferably has the interplanar spacing or density and crystallite size described in Japanese Patent Publication No. 62-22066, Japanese Patent Publication No. 2-6856, and Japanese Patent Publication No. 3-45473. The carbonaceous material does not need to be a single material; a mixture of natural graphite and artificial graphite described in Japanese Patent Publication No. 5-90844, graphite having a coating layer described in Japanese Patent Publication No. 6-4516, etc., can also be used. Hard carbon or graphite is preferably used as the carbonaceous material, and graphite is more preferably used.

[0056] The oxides of metals or metalloid elements used as negative electrode active materials are not particularly limited as long as they are oxides capable of intercalating and releasing lithium, and include metal oxides, composite oxides of metal elements or composite oxides of metal elements and metalloid elements (collectively referred to as metal composite oxides), and 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, metalloid elements refer to elements that exhibit properties intermediate between metal elements and nonmetal elements, and usually include the six elements boron, silicon, germanium, arsenic, antimony, and tellurium, and further include the three elements selenium, polonium, and astatine. Furthermore, amorphous means having a broad scattering band with peaks in the region of 20° to 40° at 2θ values ​​in X-ray diffraction using CuKα rays, and may have crystalline diffraction lines. Preferably, the strongest intensity of the crystalline diffraction lines observed at 40° to 70° 2θ is 100 times or less, more preferably 5 times or less, the intensity of the diffraction line at the peak of the broad scattering band observed at 20° to 40° 2θ, and it is particularly preferable that there are no crystalline diffraction lines.

[0057] Among the group of compounds consisting of amorphous oxides and chalcogenides described above, amorphous oxides of metalloid elements or the chalcogenides described above are more preferred, and oxides (compounds) consisting of one element selected from groups 13 (IIIB) to 15 (VB) of the periodic table (for example, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) or a combination of two or more such elements, or chalcogenides 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 Preferably, the following can be used in combination with amorphous oxides mainly composed of Sn, Si, and Ge: carbonaceous materials capable of intercalating and / or releasing lithium ions or lithium metal, elemental lithium, lithium alloys, and negative electrode active materials that can be alloyed with lithium.

[0058] From the viewpoint of high current density charge-discharge characteristics, oxides of metals or metalloid elements, particularly metal (composite) oxides and the above chalcogenides, preferably contain at least one of titanium and lithium as constituent components. Examples of lithium-containing metal composite oxides (lithium composite metal oxides) include composite oxides of lithium oxide and the above metal (composite) oxide or the above chalcogenide, more specifically Li ２ SnO ２ Examples include: The negative electrode active material, for example, a metal oxide, is also preferably one that contains titanium (titanium oxide). Specifically, Li ４ Ti ５ O １２ Lithium titanate (LTO) is preferable because it exhibits excellent rapid charge-discharge characteristics due to its small volume fluctuation during lithium ion intercalation and deintercalation, which suppresses electrode degradation and improves the lifespan of lithium-ion secondary batteries.

[0059] 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 the negative electrode active material for secondary batteries. For example, lithium aluminum alloy, specifically a lithium aluminum alloy in which lithium is the base metal and 10% by mass of aluminum is added, is an example.

[0060] The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is one that is commonly used as a negative electrode active material in secondary batteries. Such active materials expand and contract significantly due to charging and discharging of all-solid-state secondary batteries, accelerating the deterioration of cycle characteristics. However, because the electrode composition of the present invention contains the above-mentioned polymer binder, the deterioration of cycle characteristics (including high-voltage cycle characteristics) can be suppressed. Examples of such active materials include (negative electrode) active materials (alloys, etc.) having silicon or tin elements, and various metals such as Al and In. Negative electrode active materials having silicon elements (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 (for example, 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 (graphite and acetylene black, etc.). That is, the amount of Li ions absorbed per unit mass increases. Therefore, the battery capacity (energy density) can be increased. As a result, there is the advantage of being able to extend the battery life. Examples of silicon-containing active materials include Si and SiO. ｘ Silicon materials such as (0 < x ≤ 1), and also silicon-containing alloys containing titanium, vanadium, chromium, manganese, nickel, copper, lanthanum, etc. (for example, LaSi ２ , VSi ２ La-Si, Gd-Si, Ni-Si), or organized active material (e.g., LaSi ２ / Si), and also SnSiO ３ SnSiS ３ Examples include active materials containing silicon and tin elements. ｘ It can be used as a negative electrode active material (metallic oxide) itself, and since it generates Si through the operation of an all-solid-state secondary battery, it can be used as a negative electrode active material (its precursor material) that can be alloyed with lithium. Examples of negative electrode active materials containing the tin element include Sn, SnO, and SnO. ２ SnS, SnS ２Furthermore, active materials containing the above-mentioned silicon and tin elements are also mentioned. Also, composite oxides with lithium oxide, for example, Li ２ SnO ２ You could also list these.

[0061] In the present invention, the above-mentioned negative electrode active material can be used without particular limitation, but in terms of battery capacity, a negative electrode active material that can be alloyed with lithium is preferred as the negative electrode active material, and among these, the above-mentioned silicon material or silicon-containing alloy (alloy containing the element silicon) is more preferred, and it is even more preferred to contain silicon (Si) or a silicon-containing alloy.

[0062] The chemical formula of the compound obtained by the above calcination method can be calculated using inductively coupled plasma (ICP) emission spectroscopy as a measurement method, or, as a simpler method, from the mass difference of the powder before and after calcination.

[0063] The shape of the negative electrode active material is not particularly limited, but it is preferably particulate in the electrode composition. When the negative electrode active material is particulate, the particle size of the negative electrode active material is not particularly limited, but is preferably 0.1 to 60 μm. The particle size of the negative 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 also the same as the method for measuring the particle size of the inorganic solid electrolyte.

[0064] The electrode composition may contain one or more types of negative electrode active materials.

[0065] In the present invention, when the negative electrode active material layer is formed by charging a secondary battery, ions of metals belonging to Group 1 or Group 2 of the periodic table, which are generated within the all-solid-state secondary battery, can be used instead of the negative electrode active material. By bonding these ions with electrons and depositing them as a metal, the negative electrode active material layer can be formed.

[0066] (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 surface coating agents include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specifically, examples include spinel titanate, tantalum oxides, niobium oxides, lithium niobate compounds, and specifically Li ４ Ti ５ O１２ 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 PO ４ Li ２ MoO ４ Li ３ BO ３ LiBO ２ Li ２ CO ３ Li ２ SiO ３ SiO ２ , TiO ２ , ZrO ２ Al ２ O ３ , B ２ O ３ These are some examples. Furthermore, the electrode surface containing the positive electrode active material or negative electrode active material may be surface-treated with sulfur or phosphorus. In addition, the particle surface of the positive electrode active material or negative electrode active material may be surface-treated with active light or active gas (plasma, etc.) before or after the above surface coating.

[0067] [Conductive Additive] The electrode composition of the present invention contains a conductive additive. In particular, when a silicon-containing active material is used as the negative electrode active material, it is preferable to use it in combination with a conductive additive. There are no particular restrictions on the conductive additive, and any commonly known conductive additive can be used. For example, it may be an electronically conductive material such as graphite, artificial graphite, or other graphites; carbon blacks such as acetylene black, Ketjen black, or furnace black; amorphous carbon such as needle coke; carbon fibers such as vapor-grown carbon fibers or carbon nanotubes; or carbonaceous materials such as graphene or fullerene. Alternatively, it may be metal powders or metal fibers such as copper or nickel, or conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, or polyphenylene derivatives may be used. In the present invention, when the active material and the conductive additive are used in combination, the conductive additive is one of the above conductive additives that does not function as an active material because insertion and release of metal ions (preferably Li ions) belonging to Group 1 or Group 2 of the periodic table does not occur when the battery is charged or discharged. Therefore, among conductive additives, those that can function as active materials in the active material layer when the battery is charged and discharged are classified as active materials, not conductive additives. Whether or not a conductive additive functions as an active material when the battery is charged and discharged is not singular, but is determined by its combination with the active material.

[0068] The conductive additive is preferably in particulate form in the electrode composition. When the conductive additive is in particulate form, the particle size (volume average particle size) of the conductive additive is not particularly limited, but for example, 0.02 to 1.0 μm is preferred. The particle size of the conductive additive can be adjusted in the same way 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 electrode composition may contain one or two types of conductive additives.

[0069] [Binding Agent] The electrode composition of the present invention contains a binding agent. The binding agent is not particularly limited as long as it is a polymer binder made of a polymer (hereinafter sometimes referred to as "polymer used in the present invention" or "polymer of the present invention") containing 30 to 99.9% by mass of the constituent unit represented by formula A described later, and the electrode composition contains a polymer binder that dissolves in the dispersion medium described later. The polymer of the present invention contained in the polymer binder may be one type or two or more types.

[0070] In the present invention, "a polymer binder containing the polymer of the present invention" encompasses both forms: a binder consisting of the polymer of the present invention itself, and a binder comprising the polymer of the present invention and other components. Other components that may be included in the binder are not particularly limited, but include polymers other than the polymer of the present invention, by-products of the synthesis of the polymer of the present invention, decomposition products (residues) of polymerization catalysts, residual synthesis solvents, etc. 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), which will be described in detail later. 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.

[0071] The binder, or at least the polymer binder (the polymer of the present invention), exhibits the property of dissolving in the dispersion medium contained in the electrode composition (solubility). That is, the binder, or at least the polymer binder, in the electrode composition exists in a dissolved state in the dispersion medium, depending on its content. When the binder, or at least the polymer binder, is dissolved in the dispersion medium, it can stably exhibit the function of dispersing solid particles in the dispersion medium, thereby improving the dispersion state of solid particles in the electrode composition. Solubility will be explained below using the polymer binder as an example. In the present invention, the dissolution of the polymer binder in the dispersion medium is not limited to the state in which all (total amount) of the polymer binder is dissolved in the dispersion medium. For example, if the solubility in the dispersion medium is 50% or more, a portion of the polymer binder may exist insolublely in the electrode composition. If 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 requirement. The method for measuring solubility is as follows. Specifically, approximately 0.1 g of polymer binder (solid) is accurately weighed, and this weighed mass is defined as W0. Next, the polymer binder and 10 g of dispersion medium are placed in a container and mixed using a mix rotor (model VMR-5, manufactured by AS ONE Corporation) at 25°C and 100 rpm for 48 hours. After that, insoluble matter is filtered from the solution, and the resulting solid is vacuum-dried at 120°C for 3 hours, and the mass W1 of the insoluble matter is accurately weighed. Then, the solubility (%) in the dispersion medium is calculated according to the following formula: Solubility (%) = (W0 - W1) / W0 × 100

[0072] In the present invention, the solubility of the polymer binder in the dispersion medium can be appropriately imparted depending on the structure and composition (types and content of constituent units) of the polymer of the present invention, as well as the combination with the dispersion medium.

[0073] <Polymer of the Present Invention> The polymer of the present invention contains at least 30 to 99.9% by mass of constituent unit A represented by the following formula A in its molecular structure. (Constituent unit A)

[0074]

[0075] In equation A, R１ R represents a hydrogen atom or a methyl group. ２ The group comprises an alkyl group having 6 to 24 carbon atoms or a siloxane bond, and an alkyl group having 6 to 24 carbon atoms is preferred because it can improve the dispersibility of the polymer binder and solid particles, as well as the handling properties (adhesion to the current collector) of the electrode sheet for all-solid-state secondary batteries.

[0076] R ２ The alkyl group having 6 to 24 carbon atoms can be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, with linear alkyl groups or branched alkyl groups being preferred. When the alkyl group has 6 to 24 carbon atoms, the polymer of the present invention can exhibit solubility in the dispersion medium, and while maintaining excellent handling properties, the dispersibility of the polymer binder and solid particles can be improved. In terms of dispersibility of the polymer binder and solid particles, and handling properties, the alkyl group has 6 to 20 carbon atoms, more preferably 8 to 18, and even more preferably 10 to 14 carbon atoms. ２ The alkyl group that can be used may have substitution groups. Examples of substituents include groups selected from substituent Z described later, and may be polar functional groups (a) described later, but it is preferable that the substituent be something other than polar functional groups (a).

[0077] R ２ The group containing a siloxane bond (Si-O- bond) that can be used as is not particularly limited as long as it contains at least one siloxane bond, but it is preferable that it contains a group containing multiple siloxane bonds, i.e., a polymer chain made of polysiloxane, in terms of dispersibility, handling, etc. The content of siloxane bonds (degree of polymerization) in this polymer chain is not particularly limited and can be determined as appropriate, for example by considering the number-average molecular weight of the polymer chain and the molecular weight of the constituent unit represented by formula A, which will be described later, and is preferably as described later.

[0078] Groups containing a siloxane bond include -(Si(R Ｓ ２ )-O) ｎｓ A polymer chain having a structure represented by - is preferred.Ｓ represents a hydrogen atom or a substituent, and substituents are preferred. The substituent is not particularly limited and can be selected from substituent Z described later, and includes hydroxyl groups, alkyl groups (preferably 1 to 12 carbon atoms, more preferably 1 to 6, and particularly preferably 1 to 3 carbon atoms), alkenyl groups (preferably 2 to 12 carbon atoms, more preferably 2 to 6, and particularly preferably 2 or 3 carbon atoms), alkoxy groups (preferably 1 to 24 carbon atoms, more preferably 1 to 12, even more preferably 1 to 6, and particularly preferably 1 to 3 carbon atoms), aryl groups (preferably 6 to 22 carbon atoms, more preferably 6 to 14, and particularly preferably 6 to 10 carbon atoms), aryloxy groups (preferably 6 to 22 carbon atoms, more preferably 6 to 14, and particularly preferably 6 to 10 carbon atoms), aralkyl groups (preferably 7 to 23 carbon atoms, more preferably 7 to 15, and particularly preferably 7 to 11 carbon atoms), and groups represented by formula Z described later. Among these, alkyl groups with 1 to 3 carbon atoms, phenyl groups, or groups represented by formula Z described later are more preferred, and alkyl groups with 1 to 3 carbon atoms are even more preferred. ns represents the degree of polymerization (average number of repeats) of the siloxane structure, and is appropriately determined considering the number-average molecular weight of the polymerization chain and the molecular weight of the constituent unit (X), as described later, and is preferably as described later.

[0079] The polysiloxane structure has terminal groups attached to its ends. These terminal groups are not particularly limited and can be hydrogen atoms or substituents. Possible substituents as terminal groups include groups selected from substituent Z described later, for example, R Ｓ Possible substituents include:

[0080] The polysiloxane structure is preferably a polysiloxane structure having the chemical structure represented by the following formula 4A.

[0081] In formula 4A, R １５ and R １６ R represents an alkyl group or aryl group, and Z represents a group represented by formula (Z) described later. １５ , R １６ And Z are R in Equation 4, which will be described later. １５ , R １６And is the same as Z. In equation 4A, x1, x2, and x3 are integers greater than or equal to 0, and y1 is an integer from 1 to 30. x1, x2, x3, and y1 in equation 4A are the same as x1, x2, x3, and y1 in equation 4 described later.

[0082] R ２ As a structural unit represented by formula A having a group containing a siloxane bond, the structural unit represented by the following formula 4 is preferred.

[0083]

[0084] In formula 4, R １１ R represents a hydrogen atom or a methyl atom, and the above R represents a hydrogen atom or a methyl atom. １ It is the same as B. ２ indicates a linking group. B ２ The linking group that can be used is not particularly limited, and examples include linking groups that link polymerizable groups and terminal substituents, which will be described later. Specifically, alkylene groups, alkenylene groups, arylene groups, oxygen atoms, sulfur electrons, carbonyl groups, or combinations thereof are preferred, groups containing a -CO-O- group are more preferred, and -CO-O- or -CO-O-alkylene groups are particularly preferred.

[0085] R １５ R represents an alkyl group or an aryl group, with alkyl groups being preferred. １５ The alkyl and aryl groups that can be selected are, respectively, the R in the polysiloxane structure described above. Ｓ This is synonymous with alkyl and aryl groups that can be taken as, and the preferred ones are also the same. However, R １５ Methyl is particularly preferred. Two Rs bonded to the same silicon atom １５ These may be the same or different, but it is preferable that they are all methyl. １６ This represents an alkyl group or an aryl group, with alkyl groups being preferred. Two R groups bonded to the same silicon atom １６ These may be the same or different. １６ The alkyl and aryl groups that can be selected are, respectively, the R in the polysiloxane structure described above. ＳThis is synonymous with alkyl and aryl groups that can be taken as, and the preferred ones are also the same. However, R １６ Methyl is particularly preferred. １６Ａ R represents a hydrogen atom or substituent. １６Ａ The substituents that can be taken are not particularly limited, and include substituent Z described later, and the above R Ｓ A substituent that can be taken as is is preferred. However, R １６Ａ The substituents that can be taken are more preferably alkyl groups, alkenyl groups, aralkyl groups, aryl groups, alkoxy groups, and aryloxy groups, with alkyl groups being even more preferred.

[0086] Z represents the group shown by the following formula (Z).

[0087] In formula (Z), R １７ and R １８ Each represents either an alkyl group or an aryl group. １７ and R １８ The alkyl and aryl groups that can be selected are, respectively, the R in the polysiloxane structure described above. Ｓ This is synonymous with alkyl and aryl groups that can be taken as, and the preferred ones are also the same. １７ and R １８ They may be the same or different. １９ represents an unsubstituted alkyl group having 1 to 4 carbon atoms. y2 is an integer from 1 to 100, preferably an integer from 1 to 50, and more preferably an integer from 1 to 20.

[0088] In the constituent units represented by Equation 4, x1, x2, x3, y1, and y2 are appropriately determined considering the number-average molecular weight of the polymerization chain and the molecular weight of the constituent unit (X), as described later. The sum of x1, x2, x3, y1, and y2 (degree of polymerization) is as described later, and it is particularly preferable that the value of (x1 + x2 + x3) × y1 is the same as the degree of polymerization described later. For example, in Equation 4, x1, x2, and x3 are each integers of 0 or more. x1 is preferably an integer from 0 to 50, and more preferably an integer from 0 to 20. x2 is preferably an integer from 0 to 50, and more preferably an integer from 0 to 20. x3 is preferably an integer from 1 to 100, and more preferably an integer from 1 to 30. The sum of x1, x2, and x3 is an integer from 1 to 100, preferably an integer from 2 to 70, and more preferably an integer from 2 to 50. When x1 and x3 are integers greater than or equal to 2, in equation 4, two Z or R atoms bonded to the same silicon atom １５ These may be the same or different from each other. y1 is an integer from 1 to 30, preferably from 1 to 20, and more preferably from 1 to 10. It is preferable that x1, x2, x3, y1, and y2 are 0, x3 is an integer from 1 to 100, and y1 is an integer from 1 to 30.

[0089] When the group containing a siloxane bond in constituent unit A is a polymerization chain containing a polysiloxane bond, the number-average molecular weight of constituent unit A is not particularly limited, but is preferably 600 or more, and more preferably 800 or more, in terms of achieving a good balance between dispersibility and handling. The upper limit is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, particularly preferably 7,000 or less, and most preferably 5,000 or less. The number-average molecular weight of constituent unit A can be measured as the number-average molecular weight on a standard polystyrene basis, in the same way as the weight-average molecular weight of the polymer of the present invention. Furthermore, the degree of polymerization of all structural units forming the polymerization chain is not particularly limited, but is preferably 2 to 800, more preferably 2 to 200, and even more preferably 6 to 80.

[0090] In structural unit A, R １ and R ２ the combination is not particularly limited, and preferred R １ and preferred R ２ can be combined as appropriate.

[0091] The content of structural unit A represented by Formula A above, based on 100% by mass of all structural units constituting the polymer of the present invention, is 30 to 99.9% by mass. When the polymer of the present invention contains the structural unit A in the above content, the dispersibility of the polymer binder and solid particles, and further the handleability of an electrode sheet for an all-solid-state secondary battery can be improved. The content of structural unit A is preferably 55 to 99.5% by mass, and more preferably 65 to 99% by mass, from the viewpoint that dispersibility and handleability can be further enhanced.

[0092] In addition to structural unit A represented by Formula A above, it is preferable that the polymer of the present invention contains at least one selected from the group consisting of a structural unit represented by Formula B below, a structural unit represented by Formula C, and a structural unit represented by Formula D, from the viewpoint that dispersibility and handleability can be further enhanced.

[0093]

[0094] In Formula B, R ３ represents a hydrogen atom or a methyl group, R ４ and R ５ each represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and R ４ and R ５ may be bonded to each other. In Formula C, R ６ and R ７ each represents a hydrogen atom or a methyl group, R ８ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, R ９ and R １０ each represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and R ９ and R １０ may be bonded to each other. In Formula D, R １１ and R １２ each represents a hydrogen atom or a methyl group, and R １３ represents a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, or a phenyl group.

[0095] (Structural Unit B) In the structural unit B represented by Formula B, R ４ and R ５ examples of the alkyl group having 1 to 18 carbon atoms that can be used as include any of a straight-chain alkyl group, a branched alkyl group, or a cyclic alkyl group, with a straight-chain alkyl group or a branched alkyl group being preferred. When the alkyl group has 1 to 18 carbon atoms, the handleability of an electrode sheet for an all-solid-state secondary battery can be improved while maintaining the dispersibility of the polymer binder and solid particles. The number of carbon atoms in the alkyl group is preferably from 1 to 12, more preferably from 2 to 8, and even more preferably from 2 to 6, from the viewpoints of dispersibility and handleability. R ４ and R ５ as a combination, it is preferred that at least one of R ４ and R ５ is an alkyl group having 1 to 18 carbon atoms, and both R ４ and R ５ may both be alkyl groups having 1 to 18 carbon atoms. When both R ４ and R ５ are alkyl groups, the two alkyl groups may be the same or different, and a combination of short-chain alkyl groups having 1 to 4 carbon atoms is preferred from the viewpoint of handleability. Note that R ４ and R ５ may be bonded to each other to form a ring structure containing a nitrogen atom. In this ring structure, a carbon atom of the alkyl group may be substituted with a heteroatom (for example, each atom such as oxygen, sulfur, phosphorus, etc.). Examples of the ring structure that R ４ and R ５ may be bonded to each other to form include nitrogen-containing saturated heterocycles, such as a pyrrolidine ring, a piperidine ring, a piperazine ring, a morpholine ring, and a thiomorpholine ring.

[0096] As the structural unit B, a structural unit represented by the following formula (B1) is also preferred.

[0097] In the above formula (B1), X １ represents a hydrogen atom or a methyl group, and is the same as the above R ３ L１ This indicates a single bond. １ and Y ２ Each represents either a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. １ and Y ２ The alkyl group that can be taken as is R ４ and R ５ It is the same as an alkyl group having 1 to 18 carbon atoms that can be used as Y. １ and Y ２ Preferably, at least one of them is an alkyl group having 1 to 18 carbon atoms, Y １ and Y ２ Both may be alkyl groups having 1 to 18 carbon atoms. １ and Y ２ If both take alkyl groups, Y １ and Y ２ The combinations of alkyl groups that can be taken as are not particularly limited, as described above. ４ and R ５ This is the same combination as [the other combination].

[0098] Constituent unit B, for example, Y １ and Y ２ The alkyl group that can be used may have substituents. Examples of substituents include groups selected from substituent Z described later, with polar functional group (a), described later, being preferred in terms of adhesion, and hydroxyl groups being more preferred in that they also exhibit good adsorption to solid particles.

[0099] In constituent unit B, R ３ , R ４ and R ５ The combinations are not particularly limited, and each code R ３ ~R ５ The desirable elements can be combined as needed.

[0100] (Constituent unit C)

[0101] The constituent unit C represented by the above formula C is maleic anhydride or the ring-opened form of the imide ring of the constituent unit D described later. Examples include reaction products of maleic anhydride or constituent unit D with a compound containing active hydrogen (active hydrogen compound), or substituted products obtained by further substituting the reaction product of maleic anhydride or constituent unit D with an active hydrogen compound, particularly water, with another active hydrogen compound. The active hydrogen compound is not particularly limited as long as it is a compound that reacts with the succinic anhydride ring, which is the copolymer unit of maleic anhydride, or the imide ring of constituent unit D. Examples include water, alcohol compounds, amine compounds, thiol compounds, etc. These active hydrogen compounds are R in the above formula C. ８ or R ９ and R １０ Compounds corresponding to atoms or groups that can be taken as are appropriately selected and used, for example alkyl alcohols, monoalkylamines, dialkylamines, etc. In the constituent unit C, R ６ and R ７ Each of these represents either a hydrogen atom or a methyl group, with a hydrogen atom being preferred. ６ and R ７ The combinations are not particularly limited, but combinations in which at least one is a hydrogen atom are preferred, and combinations in which both are hydrogen atoms are more preferred.

[0102] R ８ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, with a hydrogen atom being preferred. ８ The alkyl group having 1 to 18 carbon atoms that can be used as R is not particularly limited, ４ and R ５ It is the same as an alkyl group having 1 to 18 carbon atoms that can be used as R. ９ and R １０ Each represents either a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ９ and R １０ The alkyl group having 1 to 18 carbon atoms that can be used as R is not particularly limited, ４ and R ５ It is the same as an alkyl group having 1 to 18 carbon atoms that can be used as R. ９ and R １０ As for combinations, R ９and R １０ Preferably, at least one of them is an alkyl group having 1 to 18 carbon atoms, R ９ and R １０ Both may be alkyl groups having 1 to 18 carbon atoms. ９ and R １０ When both are alkyl groups, the two alkyl groups may be the same or different, and a combination of short-chain alkyl groups having 1 to 4 carbon atoms is preferred in terms of handling. ９ and R １０ These may be bonded to each other to form a ring structure containing a nitrogen atom. ９ and R １０ The ring structures that may be formed by bonding with each other include R ４ and R ５ This is the same as a ring structure that may be formed by the bonding of these elements together.

[0103] Constituent unit C, for example R ９ and R １０ The alkyl group that can be used may have substituents. Examples of substituents include groups selected from substituent Z described later, with polar functional group (a), described later, being preferred in terms of adhesion, and a hydroxyl group being more preferred.

[0104] In constituent unit C, R ７ ~R １０ The combinations are not particularly limited, and each code R ７ ~R １０ The desirable elements of these can be combined as appropriate, R ６ ~R ８ Both are hydrogen atoms, R ９ and R １０ Preferred examples include constituent units that combine with preferred elements.

[0105] (Constituent unit D)

[0106] In constituent unit D, R １１ and R １２ Each of these represents either a hydrogen atom or a methyl group, with a hydrogen atom being preferred. １１ and R １２The combination is not particularly limited, but combinations in which at least one is a hydrogen atom are preferred, and combinations in which both are hydrogen atoms are more preferred. １３ R represents a hydrogen atom, a C1-C16 alkyl group, or a phenyl group. A C1-C16 alkyl group or a phenyl group is preferred because it can improve the handling properties of the electrode sheet for all-solid-state secondary batteries while maintaining the dispersibility of the polymer binder and solid particles. １３ The alkyl group having 1 to 16 carbon atoms can be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, with linear alkyl groups or branched alkyl groups being preferred. When the alkyl group has 1 to 16 carbon atoms, the handling properties of the electrode sheet for all-solid-state secondary batteries can be improved while maintaining the dispersibility of the polymer binder and solid particles. The alkyl group can also have 1 to 24 or 2 to 18 carbon atoms, but in terms of dispersibility and handling properties, it is preferably 2 to 12, more preferably 2 to 8, and even more preferably 2 to 6.

[0107] Constituent unit D, for example R １３ The alkyl or phenyl group that can be used may have substituents. Examples of substituents include groups selected from substituent Z described later, and the polar functional group (a) described later is preferred in terms of adhesion.

[0108] In constituent unit D, R １１ ~R １３ The combinations are not particularly limited, and each code R １１ ~R １３ The desirable elements of these can be combined as appropriate, R １１ and R １２ Both are hydrogen atoms, R １３ Preferred examples include constituent units that combine with preferred elements.

[0109] The polymer of the present invention preferably contains the above-mentioned structural unit A and at least one of the above-mentioned structural unit B, structural unit C, and structural unit D, and more preferably contains structural unit A and any one of structural unit B, structural unit C, and structural unit D. The polymer of the present invention may also contain structural units other than structural units A to D (which may be referred to as "other structural units" in the present invention). The total content of structural units B, structural unit C, and structural unit D in relation to 100% by mass of all structural units constituting the polymer of the present invention is not particularly limited and can be appropriately determined considering the content of structural unit A as described above, as well as dispersibility and handling properties. For example, the total content of structural units B, structural unit C, and structural unit D is preferably 0.1 to 65% by mass, more preferably 0.5 to 45% by mass, and even more preferably 1 to 35% by mass.

[0110] In one preferred embodiment of the present invention, the polymer is a (meth)acrylic polymer AB ((meth)acrylic polymer, (meth)acrylamide polymer) containing constituent unit A and constituent unit B. In this embodiment, the (meth)acrylic polymer is a constituent unit A1 (R) represented by the following formula A1. ２ A preferred form is a (meth)acrylic polymer AB1 containing a constituent unit A, which is an alkyl group having 6 to 24 carbon atoms, and a constituent unit B represented by the following formula B.

[0111]

[0112] In equation A1, R １ R in formula A represents a hydrogen atom or a methyl group. １ It is the same as R. ２ This represents an alkyl group having 6 to 24 carbon atoms, and R in formula A ２ It is the same as an alkyl group having 6 to 24 carbon atoms that can be taken as R. ３ R represents a hydrogen atom or a methyl group. ４ and R ５ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ４ and R ５ R in formula B may be combined.３ ~R ５ This is as stated above.

[0113] In (meth)acrylic polymer AB1, the content of constituent unit A1 is appropriately determined within the range of the above-mentioned content of constituent unit A, taking into consideration dispersibility and handling properties. The content of constituent unit A1 is preferably 30 to 82% by mass, more preferably 35 to 80% by mass, and even more preferably 45 to 78% by mass, in which dispersibility and handling properties can be further improved. In (meth)acrylic polymer AB1, the content of constituent unit B is appropriately determined within the range of the total content of constituent units B, C, and D, taking into consideration dispersibility and handling properties. The content of constituent unit B is preferably 18 to 45% by mass, more preferably 22 to 40% by mass, and even more preferably 25 to 33% by mass, in which dispersibility and handling properties can be further improved.

[0114] In a preferred embodiment of the polymer of the present invention, a (meth)acrylic polymer AB containing constituent unit A and constituent unit B is a constituent unit A2 (R ２ Another preferred form is a (meth)acrylic polymer AB2 containing a constituent unit A which is a group containing a siloxane bond, and a constituent unit B represented by the following formula B.

[0115]

[0116] In equation A2, R １ R in formula A represents a hydrogen atom or a methyl group. １ It is the same as R. ２ This indicates a group containing a siloxane bond, and R in formula A ２ It is the same as the group containing a siloxane bond that can be taken as R. ３ R represents a hydrogen atom or a methyl group. ４ and R ５ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ４ and R ５ R in formula B may be combined. ３ ~R５ This is as stated above.

[0117] In the (meth)acrylic polymer AB2, the content of constituent unit A2 is appropriately determined within the range of the content of constituent unit A described above, taking into consideration dispersibility and handling properties. The content of constituent unit A1 is preferably 45 to 99% by mass, more preferably 50 to 97% by mass, and even more preferably 50 to 94% by mass, in order to further improve dispersibility and handling properties. In the (meth)acrylic polymer AB2, the content of constituent unit B is appropriately determined within the range of the total content of constituent units B, C, and D described above, taking into consideration dispersibility and handling properties. The content of constituent unit B is preferably 1 to 50% by mass, more preferably 3 to 50% by mass, and even more preferably 6 to 50% by mass, in order to further improve dispersibility and handling properties.

[0118] Another preferred embodiment of the present invention is a (meth)acrylic polymer ((meth)acrylic polymer, maleimide polymer, ring-opened maleimide polymer) containing at least one of constituent unit A, constituent unit C, and constituent unit D.

[0119]

[0120] In equation A, R １ R represents a hydrogen atom or a methyl group. ２ R in formula A represents an alkyl group having 6 to 24 carbon atoms or a group containing a siloxane bond. １ and R ２ As stated above, in equation C, R ６ and R ７ R represents a hydrogen atom or a methyl group. ８ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ９ and R １０ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ９ and R １０ R in formula A may be combined. ６ ~R １０ As stated above, in equation D, R１１ and R １２ R represents a hydrogen atom or a methyl group. １３ R represents a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, or a phenyl group. １１ ~R １３ This is as stated above.

[0121] As a (meth)acrylic polymer containing at least one of constituent unit A, constituent unit C, and constituent unit D, a preferred form is a (meth)acrylic polymer AC containing constituent unit A and constituent unit C. In the (meth)acrylic polymer AC, the content of constituent unit A is appropriately determined within the range of the above-mentioned content of constituent unit A, taking into consideration dispersibility and handling properties. The content of constituent unit A is preferably 50 to 99.5% by mass, more preferably 30 to 99% by mass, and even more preferably 15 to 98% by mass, in order to further improve dispersibility and handling properties. In the (meth)acrylic polymer AC, the content of constituent unit C is appropriately determined within the range of the total content of constituent units B, C, and D, taking into consideration dispersibility and handling properties. The content of constituent unit C is preferably 0.5 to 40% by mass, more preferably 1 to 15% by mass, and even more preferably 2 to 10% by mass, in order to further improve dispersibility and handling properties.

[0122] As a (meth)acrylic polymer containing at least one of constituent units A, C, and D, another preferred form is (meth)acrylic polymer AD containing constituent units A and D. In (meth)acrylic polymer AD, the content of constituent unit A is appropriately determined within the range of the above-mentioned content of constituent unit A, taking into consideration dispersibility and handling properties. The content of constituent unit A is preferably 50 to 99.5% by mass, more preferably 70 to 99% by mass, and even more preferably 75 to 98% by mass, in which dispersibility and handling properties can be further improved. In (meth)acrylic polymer AD, the content of constituent unit D is appropriately determined within the range of the total content of constituent units B, C, and D, taking into consideration dispersibility and handling properties. The content of constituent unit D is preferably 0.5 to 40% by mass, more preferably 1 to 25% by mass, and even more preferably 2 to 15% by mass, in which dispersibility and handling properties can be further improved.

[0123] As a (meth)acrylic polymer containing at least one of constituent unit A, constituent unit C, and constituent unit D, another preferred form is (meth)acrylic polymer ACD containing constituent unit A, constituent unit C, and constituent unit D. In (meth)acrylic polymer ACD, the content of constituent unit A is appropriately determined within the range of the above-mentioned content of constituent unit A, taking into consideration dispersibility and handling properties. The content of constituent unit A is preferably 50 to 99.5% by mass, more preferably 70 to 99% by mass, and even more preferably 75 to 98% by mass, in which dispersibility and handling properties can be further improved. In (meth)acrylic polymer ACD, the total content of constituent unit C and constituent unit D is appropriately determined within the range of the above-mentioned total content of constituent unit B, constituent unit C, and constituent unit D, taking into consideration dispersibility and handling properties. The total content of constituent units C and D is preferably 0.5 to 40% by mass, more preferably 1 to 25% by mass, and even more preferably 2 to 15% by mass, in order to further improve dispersibility and handling properties. In (meth)acrylic polymer ACD, the content of constituent unit C is appropriately determined within the range of the total content of constituent units B, C and D, and the total content of constituent units C and D, as described above, taking into consideration dispersibility and handling properties. The content of constituent unit C is preferably 1 to 35% by mass, more preferably 1 to 25% by mass, and even more preferably 1 to 15% by mass, in order to further improve dispersibility and handling properties. In (meth)acrylic polymer ACD, the content of constituent unit D is appropriately determined within the range of the total content of constituent units B, C and D, and the total content of constituent units C and D, as described above, taking into consideration dispersibility and handling properties. The content of constituent unit D is preferably 1 to 35% by mass, more preferably 1 to 25% by mass, and even more preferably 1 to 15% by mass, in which dispersibility and handling properties can be further improved.

[0124] [Other Structural Units] The polymer of the present invention may contain other structural units in addition to the above structural units A to D. Examples of the other structural units include a structural unit E having at least one polar functional group selected from the following functional group group (a) in the molecular structure (which may be conveniently referred to as "polar functional group (a)"), a structural unit F derived from a short-chain alkyl (meth)acrylate compound, and the like.

[0125] <Structural Unit E> When the polymer of the present invention contains the structural unit E, the dispersibility and handling properties exhibited by the structural units A to D can be further reinforced, and furthermore, the adhesion of solid particles can also be reinforced. The above structural units A to D may have a polar functional group (a) as a substituent, and the structural units A to D having a polar functional group (a) shall be regarded as the structural units A to D instead of the structural unit E.

[0126] The structural unit (A) only needs to have a polar functional group (a), and examples thereof include structural units derived from a polycondensable compound having at least one polar functional group in the functional group group (a). Examples of the polycondensable compound include a compound having a polycondensable group, the polar functional group (a) or a terminal substituent having the polar functional group (a), and optionally a linking group that links a polymerizable group and a terminal substituent, and also include a polymerizable cyclic dicarboxylic anhydride described later. More specific examples of such polycondensable compounds include: a compound in which a carbon-carbon unsaturated bond as a polymerizable group is directly bonded to the polar functional group (a); a compound in which a carbon-carbon unsaturated bond is bonded to the polar functional group (a) via a linking group; and further, a compound in which the polar functional group (a) itself contains a carbon-carbon unsaturated bond (for example, the polymerizable cyclic dicarboxylic anhydride described later). In addition, the compound having a polar functional group (a) includes compounds capable of introducing the polar functional group (a) into the polymer structural unit after polymerization through various reactions (for example, various alcohol, amino, mercapto or epoxy compounds (including polymers) capable of addition reaction or condensation reaction with a structural unit derived from carboxylic anhydride, a structural unit having a carbon-carbon unsaturated bond, etc.).

[0127] The polycondensable group can be any group copolymerizable with each of the above-mentioned structural units, for example, a polymerizable group (ethylenically unsaturated group), specifically a vinyl group. The terminal substituent is not particularly limited, but for example, a group selected from substituent Z described later can be used. Examples of groups selected from substituent Z include alkyl groups, alkenyl groups, aryl groups, heterocyclic groups, etc., with alkyl groups being preferred. The number of carbon atoms in the alkyl group that can be used as a terminal substituent is not particularly limited, but is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4.

[0128] The linking group is not particularly limited, but examples include alkylene groups (preferably with 1 to 12 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3 carbon atoms), alkenylene groups (preferably with 2 to 6 carbon atoms, more preferably 2 to 3 carbon atoms), arylene groups (preferably with 6 to 24 carbon atoms, more preferably 6 to 10 carbon atoms), oxygen atoms, sulfur atoms, and imino groups (-NR Ｎ -: R Ｎ ) represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Examples include a carbonyl group, a phosphate linking group (-O-P(OH)(O)-O-), a phosphonic acid linking group (-P(OH)(O)-O-), or a group relating to a combination thereof. However, it is preferable that the linking group is not a group corresponding to each of the polar functional groups (a) described above. Preferred linking groups are groups formed by combining an alkylene group, an arylene group, a carbonyl group, an oxygen atom, a sulfur atom, and an imino group, more preferably a group formed by combining an alkylene group, an arylene group, a carbonyl group, an oxygen atom, a sulfur atom, and an imino group, and a -CO-O- group is preferred. When a terminal substituent into which the polar functional group (a) is introduced can also correspond to a linking group, this terminal substituent is interpreted not as a linking group, but as a terminal substituent into which the polar functional group (a) is introduced.

[0129] The number of atoms constituting the above linking group is preferably 1 to 36, more preferably 1 to 24, and even more preferably 1 to 12. The number of linked atoms in 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 above number of linked atoms refers to the minimum number of atoms that connect predetermined structural parts. For example, in the case of -O-C(=O)-, the number of atoms constituting the linking group is 3, but the number of linked atoms is 2.

[0130] The polar functional group (a) is preferably present in the molecular chain that forms the side chain of the polymer of the present invention, and more preferably incorporated, for example, inside or at the end of the molecular chain that forms the side chain of the polymer of the present invention. However, if the side chain of the polymer of the present invention has a polymerization chain, the polar functional group present in the substructure that connects this polymerization chain and the main chain of the polymer is not included in the polar functional group (a) because it does not sufficiently improve adhesion. In the present invention, the molecular chain that forms 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, and is a molecular chain other than the molecular chain that constitutes the main chain of the polymer of the present invention, and is usually a molecular chain that is bonded to the molecular chain (group of atoms) that constitutes the main chain.

[0131] Each constituent unit (A) only needs to have at least one polar functional group (a), and it is generally preferable that it has one to three polar functional groups. The content (mass%) and number of polar functional groups (a) in the polymer of the present invention are not particularly limited and are appropriately determined according to the type and content of each constituent unit, the number of polar functional groups in each constituent unit, the content of constituent units having polar functional groups, the weight-average molecular weight of the polymer of the present invention, etc. <Functional group group (a)> Sulfonic acid group (sulfo group), phosphoric acid group (phosphoryl group), phosphonic acid group, hydroxyl group, carboxyl group, dicarboxylic acid group, thiol group (sulfanyl group), ether group, ester group, urethane group, urea group, imide group, fluoroalkyl group and salts thereof

[0132] The sulfonic acid group, phosphoric acid group, phosphonic acid group, etc., included in functional group (a) are not particularly limited, but are synonymous with the corresponding group of substituent Z described later. The dicarboxylic acid group is not particularly limited, but includes groups obtained by removing one or more hydrogen atoms from a dicarboxylic acid or its anhydride, and the constituent unit itself obtained by copolymerizing a polymerizable dicarboxylic acid or its anhydride as a polymerizable compound, and further includes groups obtained by cleaving the anhydride group when a dicarboxylic acid or its anhydride reacts with an active hydrogen compound. As for the group obtained by removing one or more hydrogen atoms from a dicarboxylic acid or its anhydride, groups obtained by removing one or more hydrogen atoms from an acyclic dicarboxylic acid or a cyclic dicarboxylic acid anhydride are 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 examples include dicarboxylic acids or their anhydrides having an unsaturated bond in the molecule, and is preferably a polymerizable cyclic dicarboxylic acid anhydride. Examples of polymerizable dicarboxylic acids include maleic acid and itaconic acid, and examples of polymerizable cyclic dicarboxylic acid anhydrides include maleic acid and itaconic acid. The active hydrogen compound is not particularly limited as long as it is a compound that reacts with the dicarboxylic acid anhydride group, and examples include alcohol compounds, amine compounds, thiol compounds, and specifically, the active hydrogen compounds described above in the section on constituent unit C.

[0133] Ether group (-O-), ester group (*-CO-O-**), urethane group (*-NR ＮＡ１ -CO-O-**), urea group (-NR ＮＡ１ -CO-NR ＮＡ１ -), imide group (*-CO-NR ＮＡ２ -CO-**) represents the combination shown in parentheses. Here, * and ** indicate the joining part, R ＮＡ１ R represents a hydrogen atom or substituent. ＮＡ２ R represents a bond, hydrogen atom, or substituent. ＮＡ１ and R ＮＡ２The substituents that can be taken are not particularly limited, but for example, groups selected from substituent Z described later can be listed, 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. Note that the two R in the urea group ＮＡ１ They may be the same or different. ＮＡ１ A hydrogen atom is preferred, R ＮＡ２ The bond or hydrogen atom is preferred. In each of the above groups, either of the two bond portions * and ** may be bonded to the main chain side of the polymer of the present invention, but it is preferred that bond portion * is bonded to the main chain side of the polymer of the present invention. Note that the imide group does not include a form in which the two bond portions * and ** are bonded to the main chain side of the polymer of the present invention and form a ring structure together with the atom succeeding the main chain.

[0134] The terminal groups bonded to each of these groups are not particularly limited and represent a hydrogen atom or a substituent. Examples of substituents that can be taken as terminal groups include those selected from substituent Z described later. Among these, alkyl groups (including cycloalkyl groups), aryl groups, and heterocyclic groups are preferred, with alkyl groups or aryl groups being more preferred. In the present invention, the above R ＮＡ１ If either the terminal group or the other group takes a hydrogen atom, this hydrogen atom is R ＮＡ１ It is interpreted as follows.

[0135] In the present invention, the groups exhibiting the above-mentioned bonding, such as ether groups, include those that directly bond to the molecular chains constituting the main chain of the polymer of the present invention, for example, the carbon-carbon double bond polymerization chain described later. However, the ester groups are those that bond to the molecular chains constituting the main chain of the polymer of the present invention via a linking group, and do not include ester groups that directly bond to the molecular chains constituting the main chain of the polymer of the present invention. The linking group that links the molecular chain and the ester group is not particularly limited, and the linking groups described above are examples.

[0136] Note that ether groups are included in carboxyl groups, hydroxyl groups, dicarboxylic acid anhydride groups, ester groups, etc., but the -O- group contained in these is not considered an ether group. Also, ester groups are included in urethane groups, but the -CO-O- group contained in them is not considered an ester group. Polar functional groups may form cyclic structures. For example, ether groups may form cyclic ether groups, specifically epoxy groups, oxetane groups, and tetrahydrofuranyl groups.

[0137] A fluoroalkyl group is a fluoroalkyl group in which at least one hydrogen atom in the alkyl group is replaced with a fluorine atom, and its molecular structure 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, even more preferably 2 to 8, and particularly preferably 2 to 7. In a preferred embodiment, the lower limit of the number of carbon atoms may be 3 or more, and in a preferred embodiment, if the fluoroalkyl group is linear, it may be 4 or more. In the fluoroalkyl group, some of the hydrogen atoms may be replaced with fluorine atoms, or all of the hydrogen atoms may be replaced with fluorine atoms. In the present invention, a fluoroalkyl group in which some of the hydrogen atoms are replaced with fluorine atoms is preferred, and a methylene group (-CH₂) in which the carbon atoms bonded to the main chain side of the polymer of the present invention are not replaced with fluorine atoms is preferred. ２ More preferably, a fluoroalkyl group containing a fluorinated atom (-CH) is preferred, and an ethylene group (-CH) in which any of the two or three consecutive carbon atoms, including the carbon atom bonded to the main chain side of the polymer of the present invention, are not substituted with a fluorine atom. ２ -CH ２ -) or propylene group (-CH ２ -CH ２ -CH ２A fluoroalkyl group containing (-) is even more preferred. In such a fluoroalkyl group in which some of the hydrogen atoms are substituted with fluorine atoms, it is preferable that the remaining alkyl group bonded to the carbon atom not substituted with fluorine atoms is a perfluoroalkyl group in which all of its hydrogen atoms are substituted with fluorine atoms. The fluoroalkyl group may have substituents other than fluorine atoms, for example, substituent Z described later, and suitable examples include alkyl groups, alkoxy groups, acyl groups, aryl groups, alkenyl groups, hydroxyl groups, nitro groups, cyano groups, mercapto groups, amino groups, amide groups, acidic groups (carboxyl groups, phosphoric acid groups, sulfonic acid groups, etc.).

[0138] Groups that can form salts, such as sulfonic acid groups (sulfo groups), phosphate groups, phosphonic acid groups, hydroxyl groups, carboxyl groups, and dicarboxylic acid groups, may also form salts with cations. The cations are not particularly limited and include various metal salts, ammonium or amine salts, etc. Urethane groups, urea groups, imide groups, etc., may also form salts with anions. The anions are not particularly limited and include various inorganic or organic acid anions, etc.

[0139] The polar functional groups of the polymer of the present invention are preferably sulfonic acid groups, phosphoric acid groups, phosphonic acid groups, hydroxyl groups, carboxyl groups, dicarboxylic acid groups, ether groups, imide groups, or salts thereof, with hydroxyl groups, carboxyl groups, etc. being more preferred in terms of dispersibility and handling properties.

[0140] The constituent unit E is not particularly limited, but is preferably a constituent unit derived from the polymerizable compound described above, or a constituent unit derived from a compound obtained by introducing (substituting) the polar functional group into the polymerizable compound described above, more preferably a constituent unit derived from a (meth)acrylic acid compound, more preferably a constituent unit derived from a compound obtained by introducing the polar functional group into a (meth)acrylic acid ester compound, and even more preferably a constituent unit derived from a compound obtained by introducing the polar functional group into an alkyl (meth)acrylate ester. Examples of (meth)acrylic acid ester compounds into which the polar functional group is introduced include alkyl (meth)acrylate ester compounds and aryl (meth)acrylate ester compounds, with alkyl (meth)acrylate ester compounds being preferred. The number of carbon atoms in the alkyl group constituting the alkyl (meth)acrylate ester compound is not particularly limited, but can be, for example, 1 to 24. The number of carbon atoms in the alkyl group is usually 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 constituting the aryl ester is not particularly limited, but can be, for example, 6 to 24, more preferably 6 to 10, and more preferably 6.

[0141] The content of the above-mentioned constituent unit E in 100% by mass of all constituent units constituting the polymer of the present invention is not particularly limited and is appropriately determined considering dispersibility, handling properties, the content of each of the above-mentioned constituent units, etc. The above-mentioned content of constituent unit E can be, for example, 1% by mass or more, and is preferably 12 to 50% by mass, more preferably 15 to 50% by mass, and even more preferably 20 to 45% by mass, in terms of dispersion and handling properties.

[0142] <Constituent Unit F> In addition to the above constituent units A to D, the polymer of the present invention may also contain other constituent units, such as constituent units derived from (meth)acrylic acid short-chain alkylestellal compounds and constituent units derived from vinyl compounds (these constituent units are referred to as "constituent unit F"). The number of carbon atoms in the short-chain alkyl group in the (meth)acrylic acid short-chain alkylestellal compound is usually 1 to 5, and preferably 1 to 4. The constituent unit derived from the (meth)acrylic acid short-chain alkylestellal compound is a constituent unit that does not have the above-mentioned polar functional group (a) as a substituent. The vinyl compound can be any compound other than the compounds that become constituent units A to E above, and examples include vinyl aromatic compounds such as styrene compounds, vinylnaphthalene compounds, vinylcarbazole compounds, allyl compounds, vinyl ester compounds, vinyl ether compounds, vinylpyrrolidone compounds, cyclic olefin compounds, diene compounds, carboxylic acid vinyl ester compounds, etc. The content of the above-mentioned constituent unit F in 100% by mass of all constituent units constituting the polymer of the present invention is not particularly limited and is appropriately determined considering dispersibility, handling properties, the content of each of the above-mentioned constituent units, etc. The above-mentioned content of constituent unit F can be, for example, 40% by mass or less, preferably 5% by mass or less, and more preferably 0.1 to 3% by mass, in terms of dispersion and handling properties.

[0143] The polymer of the present invention may have one or more of the above-mentioned constituent units. The content of each constituent unit in the polymer of the present invention is set within the range described above, for example, so that the total content of all constituent units is 100% by mass. If the polymer contains two or more constituent units corresponding to a specific constituent unit, the total content of these constituent units is used.

[0144] 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 homopolymerization or copolymerization of raw material compounds (monomers) by known methods. Specifically, it can be synthesized by the method described in the examples below. There are no particular limitations on the method of incorporating the polar functional group (a), and examples include copolymerization of a polycondensable compound having the polar functional group (a), using a polymerization initiator or chain transfer agent having (or producing) the polar functional group (a), utilizing polymer reactions, ene reactions to double bonds, ene-thiol reactions, or ATRP (Atom Transfer Radical Polymerization) polymerization using a copper catalyst. In addition, the polar functional group (a) can also be introduced by using functional groups present in the main chain, side chains, or terminals of the polymer of the present invention as reaction sites. For example, the polar functional group (a) can be introduced by using a compound having a functional group and various reactions with dicarboxylic acid anhydride groups in the polymer chain.

[0145] The polymer and each constituent unit of the present invention may have substituents. The substituents that the polymer and each constituent unit of the present invention may have are not particularly limited, but include groups selected from the substituent Z listed below.

[0146] - Substituent Z - Alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, e.g., methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl group (preferably an alkenyl group having 2 to 20 carbon atoms, e.g., vinyl, allyl, oleyl, etc.), alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, e.g., ethynyl, butadiinyl, phenylethynyl, etc.), cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, e.g., cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.) In this invention, the term alkyl group usually includes cycloalkyl groups, but this is described separately here.), aryl groups (preferably aryl groups having 6 to 26 carbon atoms, e.g., phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl groups (preferably aralkyl groups having 7 to 23 carbon atoms, e.g., benzyl, phenethyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, more preferably heterocyclic groups of 5 or 6 members having at least one oxygen atom, a sulfur atom, or a nitrogen atom. Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups.For example, tetrahydropyran ring group, tetrahydrofuran ring group, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, pyrrolidone group, etc.), alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms, for example, phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy group (a group in which an -O- group is bonded to the above heterocyclic group), alkoxycarbonyl group (preferably Or, alkoxycarbonyl groups having 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, etc.), aryloxycarbonyl groups (preferably aryloxycarbonyl groups having 7 to 26 carbon atoms, for example, phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), heterocyclic oxycarbonyl groups (groups in which an -O-CO- group is bonded to the above heterocyclic group), amino groups (preferably amino groups having 0 to 20 carbon atoms, alkylamino groups, arylamino groups, 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 alkylcarbonyl group, alkenylcarbonyl group, alkynylcarbonyl group, arylcarbonyl group, 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, nicotinoyloxy, etc.), allyloxy groups (preferably allyloxy groups having 7 to 23 carbon atoms, for example, benzoyloxy, naphthoyloxy, etc.), carbamoyl groups (preferably carbamoyl groups having 1 to 20 carbon atoms, for example, N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), acylamino group (preferably an acylamino group having 1 to 20 carbon atoms, e.g., acetylamino, benzoylamino, etc.), alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms, e.g., methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio group (preferably an arylthio group having 6 to 26 carbon atoms, e.g., phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), heterocyclic thio group (a group in which an -S- group is bonded to the above heterocyclic group), alkylsulfonyl group (preferably an alkylsulfonyl group having 1 to 20 carbon atoms, e.g., methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl group (preferably carbon Arylsulfonyl groups with 6 to 22 carbon atoms, for example, benzenesulfonyl), alkylsilyl groups (preferably alkylsilyl groups with 1 to 20 carbon atoms, for example, monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl), arylsilyl groups (preferably arylsilyl groups with 6 to 42 carbon atoms, for example, triphenylsilyl), alkoxysilyl groups (preferably alkoxysilyl groups with 1 to 20 carbon atoms, for example, monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl), aryloxysilyl groups (preferably aryloxysilyl groups with 6 to 42 carbon atoms, for example, triphenyloxysilyl), phosphoryl groups (preferably phosphate groups with 0 to 20 carbon atoms, for example, -OP(=O)(R, Ｐ ) ２ ), phosphonyl group (preferably a phosphonyl group having 0 to 20 carbon atoms, for example, -P(=O)(R Ｐ ) ２ ), phosphenyl group (preferably a phosphenyl group having 0 to 20 carbon atoms, for example, -P(R Ｐ ) ２ ), phosphonic acid group (preferably a phosphonic acid group having 0 to 20 carbon atoms, for example, -PO(OR Ｐ ) ２ Examples include sulfo groups (sulfonic acid groups), carboxyl groups, hydroxyl groups, sulfanyl groups, cyano groups, and halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.). Ｐis a hydrogen atom or a substituent (preferably a group selected from substituent Z). Furthermore, each of the groups listed as substituent Z may be further substituted with substituent Z. The alkyl group, alkylene group, alkenyl group, alkenylene group, alkynyl group and / or alkynylene group, etc. may be cyclic or linear, and may be linear or branched.

[0147] The polymer of the present invention may have the above-mentioned structural unit A, preferably structural units B to D, structural unit E, and optionally structural unit F, and is generally preferably a chain polymer. Among chain polymers, (meth)acrylic polymers are preferred, and the above-mentioned (meth)acrylic polymers AB, AC, AD, or ACD are more preferred in that they can achieve a high level of both dispersibility and handling properties, the above-mentioned (meth)acrylic polymers AB1, AB2, AC, or AD are even more preferred, and (meth)acrylic polymer AC or AD are particularly preferred.

[0148] The polymer of the present invention may have the above-mentioned structural unit A, and examples include hydrocarbon polymers such as styrene-based thermoplastic elastomers or their hydrides, fluoropolymers, vinyl polymers, (meth)acrylic polymers, (meth)acrylamide polymers, maleimide polymers, ring-opened maleimide polymers, etc. In terms of dispersibility, handling properties and cyclic properties, (meth)acrylic polymers (including (meth)acrylamide polymers, maleimide polymers, and ring-opened maleimide polymers) are preferred. The (meth)acrylic polymer may have structural units derived from (meth)acrylamide compounds, maleimide compounds, etc., ring-opened maleimide structural units, etc., but the polymer should contain structural units derived from (meth)acrylic compounds at a rate of 50% by mass or more out of 100% by mass of the total structural units. (Meth)acrylamide polymer, maleimide polymer, and ring-opened maleimide polymer are polymers that each contain 50% by mass or more of constituent units derived from a (meth)acrylamide compound, a maleimide compound, and a ring-opened maleimide constituent unit, respectively, per 100% by mass of all constituent units. They may also contain constituent units derived from a (meth)acrylic compound if the content is less than 50% by mass per 100% by mass of all constituent units.

[0149] The polymer of the present invention is not particularly limited in its molecular structure as long as it has the above-mentioned structural unit A, and is usually a linear polymer (straight-chain polymer) or a graft polymer. In the present invention, a linear polymer includes not only polymers that do not have a completely branched structure, but also substantially straight-chain polymers that have short molecular chains (non-polymerizable molecular structures) in addition to the main chain. A graft polymer is a polymer that has polymerizable graft chains as side chains, for example, R ２ Examples include polymers containing a structural unit A having a polymerization chain made of the above-mentioned polysiloxane. Furthermore, when the polymer of the present invention contains multiple types of structural units, the polymer of the present invention may be a block polymer, an alternating polymer, etc., but it is preferably a random polymer.

[0150] Specific examples of the polymers of the present invention include the polymers synthesized in the examples described later, but the present invention is not limited to these.

[0151] (Physical properties or characteristics of the polymer or polymer binder of the present invention) The polymer binder of the present invention exhibits a peel strength of 250 N / m or more when a 180° peel test is performed on a test piece made by bonding a binder layer formed with the polymer binder of the present invention to a current collector, and the current collector is peeled off from the binder layer at a peeling angle of 180°. Here, the current collector to be bonded to the binder layer is not particularly limited as long as it is one that is normally used as a current collector for all-solid-state secondary batteries, and any of the current collectors described later can be used, and it may be the same as or different from the electrode sheet for all-solid-state secondary batteries or the current collector used for all-solid-state secondary batteries to be made using the electrode composition of the present invention. When the electrode composition of the present invention contains a polymer binder that exhibits such high peel strength, in combination with the above-mentioned excellent dispersibility, even if the electrode active material layer is made thick, it is possible to make an electrode sheet for all-solid-state secondary batteries that exhibits excellent handling properties by increasing the adhesion between the electrode active material layer and the current collector. The 180° peel strength is more preferably 350 N / m or higher, and even more preferably 400 N / m or higher, as this exhibits superior handling properties and imparts advanced cycle characteristics to all-solid-state secondary batteries. Although the 180° peel strength has been described as a property of the polymer binder of the present invention, the polymer of the present invention also exhibits the same high 180° peel strength. In the present invention, the above 180° peel strength is the value measured in the 180° peel strength test in the examples described later. However, the content of each component in the electrode composition is not limited to the content described in the examples, but can be appropriately selected from the range defined in the present invention. In the present invention, the 180° peel strength can be appropriately set depending on the type of polymer of the present invention (type and composition of constituent units), and further depending on the type or content of the above-mentioned polar functional group (a).

[0152] In polymer binders, the adsorption rate A of inorganic solid electrolytes in the dispersion medium. ＳＥAdsorption rate A ＳＥ This value is measured using the polymer binder, inorganic solid electrolyte, and dispersion medium contained in the electrode composition, and is an index indicating the degree to which the polymer binder is adsorbed onto the inorganic solid electrolyte in this dispersion medium. Here, the adsorption of the polymer binder onto the inorganic solid electrolyte includes not only physical adsorption but also chemical adsorption, as described above. If the electrode composition contains multiple types of polymer binders, the adsorption rate is taken for polymer binders having the same composition as the polymer binders (type and content) in the electrode composition. Similarly, if the electrode composition contains multiple types of dispersion mediums, the adsorption rate is taken for dispersion mediums having the same composition as the dispersion mediums (type and content) in the electrode composition. Similarly, if the electrode composition contains multiple types of inorganic solid electrolytes, the adsorption rate is taken for multiple types of inorganic solid electrolytes. Adsorption Rate A ＳＥ (%) is the value measured by the method described in the examples below. In the present invention, adsorption rate A ＳＥ This can be appropriately set depending on the type of polymer of the present invention (type and composition of constituent units), the weight-average molecular weight of the polymer of the present invention, and further depending on the type or content of the polar functional group (a) described above, the surface state of the inorganic solid electrolyte, etc.

[0153] The weight-average molecular weight of the polymer of the present invention is not particularly limited. For example, 3 × 10 ４ The above is preferable, 5 x 10 ４ The above is more preferable, 7 x 10 ４ The above is even more preferable, 1 × 10 ５ The above is particularly preferable. The upper limit is 4 x 10 ６ The following is the actual result, but 2 x 10 ６ The following is preferable: 1 × 10 ６ The following is more preferable: 8 x 10 ５The following is even more preferable. 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, polymerization time, polymerization temperature, etc.

[0154] - Measurement of Molecular Weight - In this invention, unless otherwise specified, the molecular weight of polymers and polymer chains refers to the weight-average molecular weight or number-average molecular weight on a standard polystyrene basis, measured by gel permeation chromatography (GPC). The basic measurement method is the method set in either condition 1 or condition 2 below, but condition 2 is given priority. However, depending on the type of polymer and polymer chain, an appropriate eluent may be selected and used as appropriate. (Condition 1) Column: Two TOSOH TSKgel Super AWM-H (product 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% by mass. Detector: RI (refractive index) detector. (Condition 2) Column: A column made by connecting TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, or TOSOH TSKgel Super HZ2000 (all product names, manufactured by Tosoh Corporation). Carrier: Tetrahydrofuran. Measurement temperature: 40°C. Carrier flow rate: 1.0 ml / min. Sample concentration: 0.1% by mass. Detector: RI (refractive index) detector.

[0155] The polymer of the present invention may be a non-crosslinked polymer or a crosslinked polymer. Furthermore, if crosslinking of the polymer of the present invention progresses due to heating or the application of voltage, the molecular weight may be greater than the molecular weight described above. Preferably, the polymer of the present invention has a weight-average molecular weight within the above range when the all-solid-state secondary battery is first put into use.

[0156] The polymer of the present invention is preferably amorphous. In the present invention, "amorphous" typically means that when the glass transition temperature is measured, no endothermic peak due to crystal melting is observed. The water content 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.

[0157] <Other Polymers> The polymer binder may contain one or more other polymers to reinforce the function of the polymer of the present invention as described above. Such other polymers can be appropriately selected and used if they function as binders commonly used in all-solid-state secondary batteries. The content of the other polymers in the polymer binder is not particularly limited, but is preferably 0.01 to 4% by mass of 100% by mass of the polymer binder.

[0158] [Dispersion Medium] The electrode composition of the present invention contains a dispersion medium that disperses or dissolves each of the above components. Such a dispersion medium can be any organic compound that is liquid in the environment of use, for example, 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 can be either a nonpolar dispersion medium (hydrophobic dispersion medium) or a polar dispersion medium (hydrophilic dispersion medium), but a nonpolar dispersion medium is preferred in that it can exhibit excellent dispersibility. A nonpolar dispersion medium generally refers to a substance with low affinity for water, and in the present invention, for example, ester compounds, ketone compounds, ether compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, etc.

[0159] 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.

[0160] Examples of ether compounds 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 the 1,2-, 1,3-, and 1,4- isomers), etc.).

[0161] Examples of amide compounds 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.

[0162] 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), isobutylpropyl ketone, sec-butylpropyl ketone, pentylpropyl ketone, and butylpropyl ketone. Examples of aromatic hydrocarbon compounds include benzene, toluene, xylene, mesitylene, 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 fuel. Examples of nitrile compounds include acetonitrile, propionitrile, and isobutyronitrile. Examples of ester compounds 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.

[0163] In the present invention, ether compounds, ketone compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, and ester compounds are preferred, and ester compounds, ketone compounds, aromatic hydrocarbon compounds, or ether compounds are more preferred.

[0164] The number of carbon atoms in the compounds constituting the dispersion medium is not particularly limited, but is preferably 2 to 30, more preferably 4 to 20, even more preferably 6 to 15, and particularly preferably 7 to 12.

[0165] The boiling point of the dispersion medium at normal pressure (1 atmosphere: 101325 Pa) is not particularly limited, but is preferably 50°C or higher, and more preferably 70°C or higher. The upper limit is preferably 250°C or lower, and even more preferably 220°C or lower.

[0166] The electrode composition may contain one or more dispersion media. Examples of compositions containing two or more dispersion media include xylene (a mixture of xylene isomers with a mixed molar ratio of ortho-isomer:para-isomer:meta-isomer = 1:5:2), mixed xylene (a mixture of o-xylene, p-xylene, m-xylene, and ethylbenzene), etc. The content of the dispersion media in the electrode composition is not particularly limited and is set within a range that satisfies the above-mentioned solid content concentration.

[0167] [Lithium Salt] The electrode composition of the present invention may also preferably contain a lithium salt (supporting electrolyte). The lithium salt is preferably a lithium salt commonly used in this type of product, and is not particularly limited. For example, the lithium salt described in paragraphs 0082 to 0085 of Japanese Patent Application Publication No. 2015-088486 is preferred. When the electrode composition of the present invention contains a lithium salt, the lithium salt content is preferably 0.1 parts by mass or more, and 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, and more preferably 20 parts by mass or less.

[0168] [Dispersant] The electrode composition of the present invention does not need to contain any other dispersants (referred to as "other dispersants") because the polymer binder described above also functions as a dispersant, but it may contain other dispersants. As other dispersants, those commonly used in all-solid-state secondary batteries can be appropriately selected and used. Generally, compounds intended for particle adsorption and steric repulsion and / or electrostatic repulsion are preferably used. The electrode composition of the present invention may contain one or more other dispersants. If the electrode composition of the present invention contains other dispersants, the content of the other dispersants can be appropriately determined, for example, it can be 3% by mass or less out of 100% by mass of the solid content of the electrode composition.

[0169] [Other Additives] The electrode composition of the present invention may optionally contain, in addition to the above-mentioned components, ionic liquids, thickeners, crosslinking agents (such as those that undergo crosslinking reactions by radical polymerization, condensation polymerization, or ring-opening polymerization), polymerization initiators (such as those that generate acids or radicals by heat or light), defoaming agents, leveling agents, dehydrating agents, antioxidants, etc. The ionic liquid is included to further improve ionic conductivity, and known ionic liquids can be used without particular limitation. It may also contain polymers other than the binder-forming polymers mentioned above, commonly used binders, etc.

[0170] <Preparation of Electrode Composition> The electrode composition of the present invention can be prepared by conventional methods. For example, an inorganic solid electrolyte, an electrode active material, a conductive additive, a binder, a dispersion medium, and optionally a lithium salt and other components can be mixed using various commonly used mixers to prepare a mixture, preferably a slurry. The mixing method is not particularly limited and can be carried out using known mixers such as ball mills, bead mills, planetary mixers, blade mixers, roll mills, kneaders, disc mills, revolving mixers, and narrow-gap dispersers. The mixing conditions are also not particularly limited. For example, each component may be mixed all at once or sequentially. As for the mixing conditions, for example, the mixing temperature can be 15 to 50°C. Also, the rotation speed of the revolving mixer, etc., can be 200 to 3000 rpm (rotation per minute). The mixing time is not particularly limited and can be appropriately determined according to the dispersibility of the solid particles, for example, it can be 1 to 180 minutes. The mixing atmosphere can be any of the following: air, dry air (dew point below -20°C), or an inert gas (e.g., argon, helium, or nitrogen). Since inorganic solid electrolytes readily react with moisture, mixing is preferably carried out in dry air or an inert gas.

[0171] The electrode composition of the present invention has excellent dispersion stability (redispersibility) of solid particles, so it can be stored after preparation and does not need to be prepared each time it is used.

[0172] [Electrode Sheet for All-Solid-State Secondary Battery] The electrode sheet for all-solid-state secondary battery of the present invention is a sheet-like molded body capable of forming an electrode active material layer (particularly a positive electrode active material layer) of an all-solid-state secondary battery, and includes various embodiments depending on its application. For example, examples include an electrode, or a sheet preferably used in a laminate of an electrode and a solid electrolyte layer. The electrode sheet for all-solid-state secondary battery of the present invention is preferably a positive electrode sheet for all-solid-state secondary batteries in that it can further improve the energy density of the all-solid-state secondary battery. In the present invention, each layer constituting the electrode sheet for all-solid-state secondary battery may be a single-layer structure or a multi-layer structure.

[0173] In an electrode sheet for an all-solid-state secondary battery, the electrode active material layer, preferably the positive electrode active material layer, on a substrate such as a current collector is formed from the electrode composition of the present invention. Therefore, the electrode active material layer formed from the electrode composition of the present invention is formed from components derived from the electrode composition (excluding the dispersion medium), and the solid particles are in close contact or bound to it. It is presumed that the electrode active material layer formed from the electrode composition of the present invention contains solid particles (inorganic solid electrolyte, positive electrode active material, conductive additive) and a binder, particularly a polymer binder, dispersed or present in a nearly uniform mixture, and the binder, particularly the polymer binder, is also present on the current collector side of the electrode active material layer. Furthermore, as described above, the polymer binder of the present invention exhibits high adhesion strength with respect to the current collector, with a 180° peel strength of 250 N / m or more. As a result, the electrode sheet for an all-solid-state secondary battery exhibits excellent handling properties, as the electrode active material and the substrate such as a current collector are in close contact with each other with high adhesion strength.

[0174] Since the electrode active material layer of the electrode sheet for all-solid-state secondary batteries is formed with the electrode composition of the present invention, which has excellent dispersibility, the occurrence of excessive irregularities is suppressed, resulting in a flat surface, which contributes to improving the cycle characteristics of the all-solid-state secondary battery. The surface flatness of the electrode active material layer is preferably such that, for example, the surface roughness Rc in the examples described later is less than 10 μm. However, the content of each component in the electrode composition is not limited to the content described in the examples, but can be appropriately selected from the range defined in the present invention. An all-solid-state secondary battery incorporating an electrode sheet for all-solid-state secondary batteries having the above-described excellent properties such as surface flatness as an electrode, particularly a positive electrode, can realize an all-solid-state secondary battery with excellent cycle characteristics and high energy density.

[0175] The electrode sheet for all-solid-state secondary batteries of the present invention has an electrode active material layer that is firmly adhered to a substrate such as a current collector. Therefore, in terms of cycle characteristics, it is preferable to incorporate it directly into an all-solid-state secondary battery without peeling off the substrate.

[0176] The substrate is not particularly limited as long as it can support the electrode active material layer, and examples include sheets (plate-like bodies) of materials such as current collectors, organic materials, and inorganic materials, as described later. Examples of organic materials include various polymers, specifically polyethylene terephthalate, polypropylene, polyethylene, and cellulose. Examples of inorganic materials include glass and ceramics. In the present invention, since the electrode active material layer is firmly attached to the substrate, the substrate is preferably one that functions as a current collector in an all-solid-state secondary battery, for example, the material described later in the current collector section.

[0177] Thus, the electrode sheet for all-solid-state secondary batteries of the present invention is suitably used as a sheet-like member for forming the electrode active material layer of an all-solid-state secondary battery. Taking advantage of its properties, the electrode sheet for all-solid-state secondary batteries is preferably incorporated into an all-solid-state secondary battery as an electrode (a laminate of a current collector and an active material layer) with a current collector as a base material.

[0178] The electrode sheet for the all-solid-state secondary battery of the present invention (also simply referred to as "electrode sheet") may be any electrode sheet having an electrode active material layer. The electrode active material layer may be formed on a substrate (current collector), or it may be a sheet without a substrate, formed solely from the active material layer (a sheet with the substrate peeled off). Preferably, this electrode sheet is a sheet having a current collector and an active material layer utilizing strong adhesion. For example, it may be a sheet having a current collector, an active material layer, and a solid electrolyte layer in that order, or a sheet having a current collector, an active material layer, a solid electrolyte layer, and an active material layer in that order. Preferably, the electrode active material layer of the electrode sheet is formed from the electrode composition of the present invention. The content of each component in this electrode active material layer is not particularly limited, but preferably it is synonymous with the content of each component in the solid content of the electrode composition of the present invention. The thickness of each layer constituting the electrode sheet of the present invention is the same as the thickness of each layer described later in the all-solid-state secondary battery. The electrode sheet may have other layers. Examples of other layers include a protective layer (release sheet), a current collector, a coating layer, etc. If the electrode active material layer is not formed with the electrode composition of the present invention, it will be formed with a conventional electrode active material layer forming material.

[0179] [Method for Manufacturing Electrode Sheets for All-Solid-State Secondary Batteries] The method for manufacturing electrode sheets for all-solid-state secondary batteries of the present invention is not particularly limited, and they can be manufactured by forming an active material layer on a current collector using the electrode composition of the present invention. For example, preferably, a method is used to form a layer (coated and dried layer) made of the electrode composition by forming a film (coated and dried layer) on a substrate or current collector (may be via other layers). This makes it possible to produce electrode sheets for all-solid-state secondary batteries having a substrate or current collector and a coated and dried layer. Here, the coated and dried layer refers to a layer formed by coating the electrode composition of the present invention and drying the dispersion medium (i.e., a layer made using the electrode composition of the present invention, and consisting of a composition obtained by removing the dispersion medium from the electrode composition of the present invention). The coated and dried layer and the constituent layer may have residual dispersion medium as long as it does not impair the effects of the present invention, and the residual amount can be, for example, 3% by mass or less in each layer. In the method for manufacturing electrode sheets for all-solid-state secondary batteries of the present invention, each step such as coating and drying will be explained in the method for manufacturing all-solid-state secondary batteries below.

[0180] In this way, an electrode sheet for an all-solid-state secondary battery having an electrode active material layer prepared by appropriately pressurizing the coated and dried layer can be manufactured. The pressurizing conditions and other details will be explained later in the section on the manufacturing method of the all-solid-state secondary battery. Furthermore, in the manufacturing method of the electrode sheet for an all-solid-state secondary battery of the present invention, protective layers (especially release sheets) can also be peeled off.

[0181] [All-Solid-State Secondary Battery] The all-solid-state secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer facing the positive electrode active material layer, and a solid electrolyte layer 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 other configurations, 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, known configurations relating to all-solid-state secondary batteries can be adopted. Preferably, the positive electrode active material layer has a positive electrode current collector laminated on the surface opposite to the solid electrolyte layer to constitute the positive electrode, and preferably the negative electrode active material layer has a negative electrode current collector laminated on the surface opposite to the solid electrolyte layer to constitute the negative electrode. In the present invention, each constituent layer (including current collectors, etc.) constituting the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

[0182] In the all-solid-state secondary battery of the present invention, at least one of the electrode active material layers is formed with the electrode composition of the present invention, and it is preferable that the positive electrode active material layer is formed with the electrode composition of the present invention in order to effectively improve the energy density. In the present invention, forming the electrode active material layer of an all-solid-state secondary battery with the electrode composition of the present invention includes the embodiment of forming the electrode active material layer with the electrode sheet for all-solid-state secondary batteries of the present invention (however, if there are layers other than the layer formed with the electrode composition of the present invention (excluding the current collector), then the sheet from which these layers have been removed). The all-solid-state secondary battery of the present invention in which the electrode active material layer is formed with the electrode composition of the present invention exhibits excellent battery performance (cycle characteristics and energy density) as described above. In the present invention, each constituent layer (including the current collector, etc.) constituting the all-solid-state secondary battery may be a single-layer structure or a multi-layer structure. If the electrode active material layer is not formed with the electrode composition of the present invention, this electrode active material layer can be formed using known materials. In the present invention, each constituent layer (including the current collector, etc.) constituting the all-solid-state secondary battery may be a single-layer structure or a multi-layer structure.

[0183] [Electrode Active Material Layer] The electrode material layer formed with the electrode composition of the present invention preferably contains the same types of components and their content as those in the solid content of the electrode composition of the present invention. The thickness of the electrode active material layer (positive electrode active material layer and negative electrode active material layer) is not particularly limited, but is preferably 10 to 1000 μm, and more preferably 20 μm or more and less than 500 μm. In the all-solid-state secondary battery of the present invention, it is even 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. In the present invention, the negative electrode active material layer may be a lithium metal layer. Examples of lithium metal layers include layers formed by depositing or molding lithium metal powder, lithium foil, and lithium vapor-deposited film. 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 described above. In this case, the positive electrode active material layer of the all-solid-state secondary battery of the present invention is formed with the electrode composition of the present invention. Furthermore, when the positive electrode active material layer is formed with the electrode composition of the present invention, the negative electrode active material layer may be formed with the electrode composition of the present invention, or it may be formed with a negative electrode composition containing the inorganic solid electrolyte, the negative electrode active material, a commonly used binder, a conductive additive as appropriate, and any of the above-mentioned components, or it may be formed by a metal film such as lithium foil, or by charging as described later. Preferably, the electrode active material layer formed with the electrode composition of the present invention contains the same types of components and their content as those in the solid content of the electrode composition of the present invention.

[0184] [Solid Electrolyte Layer] The solid electrolyte layer can be formed from known materials. Preferably, the solid electrolyte layer contains the inorganic solid electrolyte having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, and contains commonly used binders, any of the above-mentioned components, etc., and usually does not contain positive electrode active material and / or negative electrode active material.

[0185] The thicknesses of the negative electrode active material layer, the solid electrolyte layer, and the positive electrode active material layer are not particularly limited. The thickness of each layer is preferably 10 to 1000 μm, and more preferably 20 μm or more and less than 500 μm. The constituent layers having the above thicknesses may be single layers or multiple layers. It is preferable to form a single-layer constituent layer with a large layer thickness using the electrode composition of the present invention, which allows for thickening by increasing the concentration. The thickness of the thickened single-layer electrode active material that can be preferably formed with the electrode composition of the present invention can be, for example, 70 μm or more, and more preferably 100 μm or more.

[0186] [Current Collector] The positive electrode active material layer and the negative electrode active material layer each have a current collector on the side opposite to the solid electrolyte layer. Electron conductors are preferred as the positive electrode current collector and the negative electrode current collector. In this invention, either the positive electrode current collector or the negative electrode current collector, or both together, may be simply referred to as the current collector. As the material for forming the positive electrode current collector, in addition to aluminum, aluminum alloys, stainless steel, nickel, and titanium, a material in which carbon, nickel, titanium, or silver has been treated on the surface of aluminum or stainless steel (a thin film has been formed) is preferred, and aluminum and aluminum alloys are more preferred. As the material for forming the negative electrode current collector, in addition to aluminum, copper, copper alloys, stainless steel, nickel, and titanium, a material in which carbon, nickel, titanium, or silver has been treated on the surface of aluminum, copper, copper alloys, or stainless steel is preferred, and aluminum, copper, copper alloys, and stainless steel are more preferred.

[0187] While film sheets are typically used as the shape of the current collector, nets, punched materials, lath materials, porous materials, foams, and molded fiber bundles can also be used. The thickness of the current collector is not particularly limited, but 1 to 500 μm is preferred. It is also preferable to create an uneven surface on the current collector surface through surface treatment.

[0188] [Other configurations] In the present invention, functional layers or components may be appropriately interposed or arranged between or outside each layer of the negative electrode current collector, negative electrode active material layer, solid electrolyte layer, positive electrode active material layer, and positive electrode current collector.

[0189] [Housing] The all-solid-state secondary battery of the present invention may be used as an all-solid-state secondary battery with the above structure in place, depending on the application. However, to make it a dry cell, it is preferable to enclose it in a suitable housing. The housing may be made of metal or resin (plastic). When using a metal housing, examples include aluminum alloy or stainless steel. It is preferable that the metal housing be divided into a positive electrode housing and a negative electrode housing, and that these be electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. It is preferable that the positive electrode housing and the negative electrode housing are joined together and integrated via a gasket to prevent short circuits.

[0190] [Preferred Embodiment of All-Solid-State Secondary Battery] A preferred embodiment of the all-solid-state secondary battery of the present invention will be described below with reference to Figure 1, but the present invention is not limited thereto.

[0191] Figure 1 is a schematic cross-sectional view showing an all-solid-state secondary battery (lithium-ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 of this embodiment has, when 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 the others and has an adjacent structure. By adopting such a structure, during charging, electrons (e － ) is supplied, and lithium ions (Li ＋ ) accumulates. On the other hand, during discharge, lithium ions (Li) accumulated on the negative electrode ＋ The discharge is returned to the positive electrode side, and electrons are supplied to the working part 6. In the illustrated example, a light bulb is used as a model for the working part 6, and it is designed to light up when the discharge occurs.

[0192] When an all-solid-state secondary battery having the layer configuration shown in Figure 1 is placed in a 2032 type coin case 11 (see, for example, Figure 2), this all-solid-state secondary battery is sometimes referred to as the all-solid-state secondary battery laminate 12, and the battery produced by placing this all-solid-state secondary battery laminate 12 in the 2032 type coin case 11 is sometimes referred to as the (coin-type) all-solid-state secondary battery 13.

[0193] <Positive electrode active material layer and negative electrode active material layer> In the all-solid-state secondary battery 10, at least one of the positive electrode active material layer 4 and the negative electrode active material layer 2 is formed of the electrode composition of the present invention, and it is preferable that the positive electrode active material layer 4 is formed of the electrode composition of the present invention in order to contribute to further improvement of the energy density of the all-solid-state secondary battery. The inorganic solid electrolyte, conductive additive and binder contained in the positive electrode active material layer 4 and the negative electrode active material layer 2 may be of the same type or different types. Furthermore, the conductive additive and binder contained in the positive electrode active material layer 4 and the negative electrode active material layer 2 may be of the same type or different types.

[0194] When the positive electrode active material layer is formed with the electrode composition of the present invention, it contains an inorganic solid electrolyte having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a positive electrode active material, a conductive additive, the above-mentioned binder, and any of the above-mentioned components, etc., to the extent that they do not impair the effects of the present invention. Note that when the positive electrode active material layer is formed with a known material, the components constituting the positive electrode active material layer are not limited to the above-mentioned components. When the negative electrode active material layer is formed with the electrode composition of the present invention, it contains an inorganic solid electrolyte having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a negative electrode active material, a conductive additive, the above-mentioned binder, and any of the above-mentioned components, etc., to the extent that they do not impair the effects of the present invention. Note that when the negative electrode active material layer is formed with a known material or is formed retrospectively by charging, etc., the components constituting the negative electrode active material layer are not limited to the above-mentioned components. The negative electrode active material layer can be formed with a known lithium metal layer. Examples of lithium metal layers include layers formed by depositing or molding lithium metal powder, lithium foil, and lithium vapor-deposited films. 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.

[0195] <Solid Electrolyte Layer> The solid electrolyte layer 3 contains an inorganic solid electrolyte having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a binder, and any of the above-mentioned components, etc., to the extent that they do not impair the effects of the present invention, and usually does not contain a positive electrode active material and / or a negative electrode active material.

[0196] In the present invention, by forming the electrode active material layer with the electrode composition of the present invention, an all-solid-state secondary battery with excellent cycle characteristics and improved energy density can be realized.

[0197] <Current Collectors> The positive electrode current collector 5 and the negative electrode current collector 1 are as described above. In the case of an all-solid-state secondary battery 10 having constituent layers other than the electrode active material layer formed with the electrode composition of the present invention, layers formed with known constituent layer forming materials can also be used. Furthermore, each layer may consist of a single layer or multiple layers.

[0198] [Manufacturing of All-Solid-State Secondary Batteries] The all-solid-state secondary battery of the present invention can be manufactured by conventional methods using the electrode composition of the present invention. For example, the all-solid-state secondary battery can be manufactured by forming an electrode active material layer using the electrode composition of the present invention. Specifically, the all-solid-state secondary battery of the present invention can be manufactured by a method (method for manufacturing an electrode sheet for an all-solid-state secondary battery of the present invention) that includes a step of applying the electrode composition of the present invention to a substrate (preferably a metal foil that will serve as a current collector) to form a coating film (film formation). More specifically, the positive electrode composition of the present invention is applied and dried on a metal foil that serves as an 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 all-solid-state secondary battery composition (inorganic solid electrolyte-containing composition) for forming a solid electrolyte layer is applied and dried on this positive electrode active material layer to form a solid electrolyte layer. Furthermore, the negative electrode composition of the present invention is applied and dried on the solid electrolyte layer to form a negative electrode. This allows for the production of an all-solid-state secondary battery with a solid electrolyte layer sandwiched between a positive electrode active material layer and a negative electrode active material layer. This can then be enclosed in a housing to create a desired all-solid-state secondary battery. Alternatively, by reversing the formation method of each layer, the negative electrode active material layer, solid electrolyte layer, and positive electrode active material layer can be formed on a negative electrode current collector, and the positive electrode current collector can be stacked on top to manufacture an all-solid-state secondary battery.

[0199] Another method is as follows: A positive electrode sheet for an all-solid-state secondary battery is prepared as described above. A negative electrode composition containing a negative electrode active material (for example, the negative electrode composition of the present invention) is applied to a metal foil which serves as the 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 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. In this way, an all-solid-state secondary battery can be manufactured. Yet another method is as follows: A positive electrode sheet and a negative electrode sheet for an all-solid-state secondary battery are prepared as described above. Separately, an inorganic solid electrolyte-containing composition is applied to a substrate to prepare a solid electrolyte sheet for an all-solid-state secondary battery consisting of a solid electrolyte layer. Furthermore, the solid electrolyte layer peeled from the substrate is laminated between a positive electrode sheet and a negative electrode sheet for all-solid-state secondary batteries. In this way, an all-solid-state secondary battery can be manufactured.

[0200] Furthermore, a positive electrode sheet or negative electrode sheet for an all-solid-state secondary battery, and a solid electrolyte sheet for an all-solid-state secondary battery are manufactured as described above. Next, the positive electrode sheet or negative electrode sheet for an all-solid-state secondary battery and the solid electrolyte sheet for an all-solid-state secondary battery are stacked on top of each other with the positive electrode active material layer or negative electrode active material layer and the solid electrolyte layer in contact, and then pressurized. In this way, the solid electrolyte layer is transferred to the positive electrode sheet or negative electrode sheet for an all-solid-state secondary battery. After that, the solid electrolyte layer from which the substrate of the solid electrolyte sheet for an all-solid-state secondary battery has been peeled off is stacked on top of the negative electrode sheet or positive electrode sheet for an all-solid-state secondary battery (with the negative electrode active material layer or positive electrode active material layer in contact with the solid electrolyte layer), and pressurized. In this way, an all-solid-state secondary battery can be manufactured. The pressurizing method and pressurizing conditions in this method are not particularly limited, and the methods and pressurizing conditions described in the pressurizing process described later can be applied.

[0201] The electrode active material layer, etc., can also be formed, for example, by press-molding the electrode composition, etc., on a substrate or active material layer under the pressurized conditions described later. In the above manufacturing method, the electrode composition of the present invention may be used for either the positive electrode composition or the negative electrode composition, and it is preferable to use the electrode composition of the present invention for at least one of the positive electrode composition and the negative electrode composition, and the electrode composition of the present invention may be used for either composition. In the present invention, when forming a solid electrolyte layer or an active material layer (excluding the active material layer formed with the electrode composition of the present invention), the material can be a commonly used composition, etc. Furthermore, instead of forming a negative electrode active material layer during the manufacture of an all-solid-state secondary battery, the negative electrode active material layer can also be formed by bonding ions of metals belonging to Group 1 or Group 2 of the periodic table, which have been accumulated on the negative electrode current collector during initialization or charging during use, etc., with electrons and depositing them as metal on the negative electrode current collector, etc.

[0202] [Formation of each layer (film formation)] The method of coating the electrode composition of the present invention and known materials is not particularly limited and can be appropriately selected. For example, coating methods (preferably wet coating) include spray coating, spin coating, dip coating, slit coating, stripe coating, bar coating, etc. The coating temperature is not particularly limited and is usually in a temperature range of about room temperature (e.g., 15 to 30°C) without heating. The coated electrode composition of the present invention may be dried after coating, or after multi-layer coating. The drying temperature is not particularly limited and is usually in a temperature range of about room temperature (e.g., 15 to 30°C) without heating. The lower limit is preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. The upper limit is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. By heating in such a temperature range, the dispersion medium can be removed and the material can be made into a solid state (coated dried layer). Furthermore, this method is preferable because it avoids raising the temperature too high and thus avoids damaging the components of the all-solid-state secondary battery. As a result, excellent cycle characteristics and high energy density can be obtained in the all-solid-state secondary battery. The drying time of the applied electrode composition of the present invention is appropriately determined according to the amount applied, the area applied, etc., but in the case of the highly concentrated electrode composition of the present invention as described above, it can be dried in a short time, for example, 10 minutes or less.

[0203] It is preferable to pressurize each layer or the all-solid-state secondary battery after applying the electrode composition of the present invention, stacking the constituent layers, or after manufacturing the all-solid-state secondary battery. It is also preferable to pressurize each layer while it is stacked. Examples of pressurizing methods include hydraulic cylinder presses. The pressurizing pressure is not particularly limited, but is generally preferably in the range of 5 to 1500 MPa. The applied electrode composition of the present invention may also be heated at the same time as pressurizing. The heating temperature is not particularly limited, but is generally in the range of 30 to 300°C. It is also possible to press at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. Furthermore, it is also possible to press at a temperature higher than the glass transition temperature of the polymer contained in the polymer binder. However, generally, the temperature should not exceed the melting point of the polymer. Pressurizing may be performed after the coating solvent or dispersion medium has been dried beforehand, or while the solvent or dispersion medium remains. Each composition may be applied simultaneously, or the coating, drying, and pressing may be performed simultaneously and / or sequentially. After applying to separate substrates, they may be laminated by transfer.

[0204] The atmosphere used in the film formation method (coating, drying, and (heated) pressurization) is not particularly limited and may be air, dry air (dew point below -20°C), or an inert gas (e.g., argon, helium, nitrogen). The pressing time may be short (e.g., within a few hours) with high pressure, or long (more than a day) with moderate pressure. For applications other than electrode sheets for all-solid-state secondary batteries, such as all-solid-state secondary batteries, a restraint device for the all-solid-state secondary battery (e.g., screw tightening pressure) may be used to maintain moderate pressure. The pressing pressure may be uniform or varied across the pressed area, such as the sheet surface. The pressing pressure can be varied according to the area or film thickness of the pressed area. The same area may also be subjected to different pressures in stages. The pressed surface may be smooth or roughened.

[0205] The electrode composition of the present invention maintains excellent dispersion stability, handling properties, and initial dispersibility even when the solid content concentration is increased. Therefore, the electrode composition can be applied at a high solid content concentration.

[0206] [Initialization] When using the highly concentrated electrode composition of the present invention in the manufacture of electrode sheets for all-solid-state secondary batteries and all-solid-state secondary batteries, the drying time after coating can be shortened, and the amount of volatilization of the dispersion medium can be reduced. As a result, productivity can be improved, environmental impact can be reduced, and manufacturing costs can be reduced. Furthermore, the electrode active material layer formed on a current collector using the electrode composition of the present invention exhibits strong adhesion to the current collector and high handling properties, as described above. Therefore, the electrode composition of the present invention is also beneficial from the viewpoint of industrial manufacturing of electrode sheets for all-solid-state secondary batteries and all-solid-state secondary batteries.

[0207] [Applications of All-Solid-State Rechargeable Batteries] The all-solid-state rechargeable battery of the present invention can be applied to a variety of uses. There are no particular limitations on the application, but for example, when mounted on electronic devices, examples include notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, cordless phone handsets, pagers, handheld terminals, portable fax machines, portable copiers, portable printers, headphone stereos, video cameras, LCD televisions, handheld vacuum cleaners, portable CDs, MiniDiscs, electric shavers, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, and backup power supplies. Other consumer applications include automobiles (electric vehicles, etc.), electric vehicles, motors, lighting fixtures, toys, game consoles, road conditioners, clocks, strobes, cameras, and medical devices (pacemakers, hearing aids, shoulder massagers, etc.). Furthermore, it can be used for various military and space applications. It can also be combined with solar cells.

[0208] The present invention will be described in more detail below based on examples, but the present invention is not to be construed as being limited thereto. In the following examples, "parts" and "%" representing the composition are by mass unless otherwise specified. In the present invention, "room temperature" means 25°C.

[0209] 1. Polymer Synthesis The polymer shown in the above specific example (chemical formula) is synthesized as follows, and a binder solution is prepared.

[0210] [Synthesis Example A-1: ​​Synthesis of Polymer A-1 and Preparation of Binder Solution A-1] Add 70 g of octadecyl methacrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 30 g of 2-hydroxyethyl methacrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.5 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to a 200 mL volumetric flask and dissolve in 70 g of ethyl acetate to prepare a monomer solution. Next, add 40 g of ethyl acetate to a 500 mL three-necked flask and stir at 70°C under a nitrogen stream, then add the above monomer solution dropwise over 2 hours. After the dropwise addition is complete, raise the temperature to 77°C and stir for 2 hours. Pour this polymerization solution into 800 g of methanol, stir for 10 minutes, and then let stand for 10 minutes. Dissolve the precipitate obtained after removing the supernatant in 300 g of mesitylene and remove the methanol by distillation by heating at 30 hPa and 80°C for 1 hour. In this way, polymer A-1 is synthesized, and a binder solution A-1 (concentration 25% by mass) made of this polymer is obtained.

[0211] [Synthesis Examples A-2 to A-33: Synthesis of Polymers A-2 to A-33 and Preparation of Binder Solutions A-2 to A-33] Except for using compounds to derive each constituent unit so that polymers A-2 to A-33 have the chemical formulas and compositions (types and content of constituent units) shown in Table 1 below, and adjusting the amount of polymerization initiator so that the weight-average molecular weights shown in Tables 1 to 4, polymers A-2 to A-33 are synthesized in the same manner as in Synthesis Example A-1, and binder solutions A-2 to A-33 consisting of each polymer are obtained. Polymers A-18 to A-20 and A-25 are synthesized by cleaving maleic anhydride to be copolymerized as described below. Specifically, for A-18 to A-20 and A-25, maleic anhydride to which constituent component C is derived is copolymerized as described above to synthesize the corresponding maleic anhydride-containing precursor polymers. Next, each precursor polymer is subjected to a ring-opening reaction with cyclohexylamine, diethanolamine, n-hexylamine, or hydroxyethylamine (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in xylene at a temperature of 90°C for 20 hours while stirring, to obtain constituent units in which maleic anhydride is cleaved.

[0212] [Synthesis Examples B-1, B-2, B-4 to B-6: Synthesis of Polymers B-1, B-2, B-4 to B-6 and Preparation of Binder Solutions B-1, B-2, B-4 to B-6] Except for using compounds to derive each constituent unit so that polymers B-1, B-2, B-4 to B-6 have the chemical formulas and compositions (types and content of constituent units) shown in Table 1 below, and adjusting the amount of polymerization initiator so that the weight-average molecular weights shown in Tables 1 to 4, polymers B-1, B-2, B-4 to B-6 are synthesized in the same manner as in Synthesis Example A-1, and binder solutions B-1, B-2, B-4 to B-6, each consisting of the respective polymers, are obtained. Note that the maleic anhydride structure of B-4 and B-6 is cleaved by heating with methanol as described above.

[0213] [Synthesis Example B-3: Synthesis of Polymer B-3 and Preparation of Binder Solution B-3] Add 50 g of deionized water, 21.5 g of vinylidene fluoride, and 28.5 g of hexafluoropropylene to an autoclave, add 0.5 g of the polymerization initiator diisopropyl peroxydicarbonate, and stir at 30°C for 24 hours. After polymerization is complete, filter the precipitate and dry at 100°C for 10 hours. Dissolve this polymer in 450 g of butyl butyrate. Polymer B-3 is synthesized in this way, and binder solution B-3 (concentration 10% by mass) consisting of this polymer is obtained.

[0214] [Synthesis Example B-7: Synthesis of Polymer B-7 and Preparation of Binder Solution B-7] In a nitrogen-purged and dried autoclave, 300 g of cyclohexane was charged as the solvent and 0.3 mL of sec-butyllithium (1.3 M, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polymerization initiator. After raising the temperature to 50°C, 5.0 g of styrene was added and polymerization was carried out for 2 hours. Subsequently, 23.2 g of 1,3-butadiene and 0.13 g of maleic anhydride were added and polymerization was carried out for 3 hours, and then 5.0 g of styrene was added and polymerization was carried out for 2 hours. This solution was reprecipitated in methanol, and the resulting solid was dried to obtain the polymer. Then, the entire amount of the polymer obtained above was dissolved in 400 parts by mass of cyclohexane in a pressure vessel, and 5% by mass of palladium carbon (palladium loading: 5% by mass) was added to the polymer as a hydrogenation catalyst, and the reaction was carried out for 10 hours under conditions of hydrogen pressure of 2 MPa and 150°C. After cooling and depressurization, palladium carbon is removed by filtration, the filtrate is concentrated, and further vacuum-dried to obtain polymer B-7. 10 g of this polymer is dissolved in 90 g of mesitylene to obtain binder solution B-7 (concentration 10% by mass) consisting of this polymer.

[0215] [Synthesis Example B-8: Synthesis of Polymer B-8 and Preparation of Binder Solution B-8] 90 g of xylene and 10 g of polymer B-7 are placed in a 1 L three-necked flask equipped with a reflux condenser and a gas inlet stopcock, and dissolved. Then, 1.12 g of diethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.) is added, the temperature is raised to 90°C, and stirring is continued for 20 hours. After that, 1 N aqueous hydrochloric acid solution is added and the organic layer is separated to remove it. The organic layer is poured into 800 g of methanol, stirred for 10 minutes, and then allowed to stand for 10 minutes. After removing the supernatant, the resulting precipitate is dissolved in 90 g of mesitylene, and the methanol is removed by distillation by heating at 30 hPa and 80°C for 1 hour. Polymer B-8 is synthesized in this way, and binder solution B-8 (concentration 10% by mass) made of this polymer is obtained.

[0216] In the chemical formula below, R is bonded to the polymerization chain made of polysiloxane. Ｙ R indicates a linking group. ＺThe '' indicates a substituent, and the degree of polymerization of the siloxane structure in the polysiloxane polymerization chain is omitted. In addition, in the polymers below, the numerical value indicated in the lower right of each constituent unit indicates the content (mass%) of that constituent unit in the polymer. In each of the polymers below, the alkyl group of each constituent unit is a linear alkyl group unless otherwise specified. In the chemical formulas below, constituent unit M-1 is derived from KF-2012 (trade name, molecular weight 4600, manufactured by Shin-Etsu Chemical Co., Ltd.), constituent unit M-2 is derived from X-22-174BX (trade name, molecular weight 2300, manufactured by Shin-Etsu Chemical Co., Ltd.), and constituent unit M-3 is derived from X-22-174ASX (trade name, molecular weight 900, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0217]

[0218]

[0219]

[0220] <Measurement of Weight-Average Molecular Weight> The weight-average molecular weight of each prepared polymer is measured using the method described above. The results are shown in the "Mw" column of Tables 1 to 4.

[0221] <Adsorption rate A ＳＥ Measurement of the adsorption rate A of each binder (polymer binder) using the inorganic solid electrolyte, polymer binder, and dispersion medium used to prepare each electrode composition shown in Tables 1 to 4. ＳＥ The mass of polymer remaining in the filtrate (mass of polymer not adsorbed by the inorganic solid electrolyte) W is measured. Specifically, 0.05 g (solid content) of polymer (polymer binder) A-1, 2.05 g of inorganic solid electrolyte LPS-1 shown in Table 1, and 6.67 g of dispersion medium (mesitylene in Example 1-1) shown in Table 1 are added to a 60 mL ointment container, and the mixture is stirred for 1 hour at room temperature at a rotation speed of 40 rpm using a mixing roller. After that, the entire amount of the obtained filtrate is dried using a membrane filter with a pore diameter of 0.2 μm, and the mass of polymer remaining in the filtrate (mass of polymer not adsorbed by the inorganic solid electrolyte) W is measured. Ａ Measure this mass W. Ａ The mass W of the polymer used in the measurement ＢThe adsorption rate of the polymer binder to the inorganic solid electrolyte is calculated using the following formula. The average value (45%) of the adsorption rates obtained by performing the above measurement twice is used as the adsorption rate A of polymer binder A-1 to the inorganic solid electrolyte LPS-1 in Example 1-1 shown in Table 1. ＳＥ The adsorption rate A of the polymer binder in the above example 1-1. ＳＥ The adsorption rate A of the polymer binder in each example and comparative example shown in Tables 1 to 4 was measured in the same manner as above. ＳＥ Each was measured, and the results are shown in Tables 1 to 4. Adsorption rate (%) = [(W Ｂ -W Ａ ) / W Ｂ ] × 100

[0222] <Evaluation of Polymer Solubility> The solubility of the polymer (polymer binder) in each electrode composition prepared in the examples described below will be measured in relation to the dispersion medium used in each example using the method described above. As a result, the solubility of the polymers used in each example and comparative example is 50% or higher, and they dissolve in the dispersion solution used in each electrode composition. "Dissolved" is indicated in the "Form" column of Tables 1 to 4.

[0223] 2. Synthesis of Sulfide-Based Inorganic Solid Electrolytes <Synthesis Example A> Sulfide-based inorganic solid electrolytes are 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), pp231-235, and A. Hayashi, S. Hama, H. Morimoto, M. Tatsumisago, T. Minami, Chem. Lett., (2001), pp872-873. Specifically, in a glove box under an argon atmosphere (dew point -70°C), lithium sulfide (Li ２ S, Aldrich, purity >99.98%, 2.42g and phosphorus pentasulfide (P ２ S ５ 3.90 g each of Aldrich (purity >99%) was weighed out and placed in an agate mortar, and mixed for 5 minutes using an agate pestle. ２ S and P２ S ５ The mixing ratio is Li in molar ratio. ２ S:P ２ S ５ The ratio is set to 75:25. Next, 66 g of 5 mm diameter zirconia beads are placed in a 45 mL zirconia container (manufactured by Fritsch), and the entire amount of the above mixture of lithium sulfide and phosphorus pentasulfide is added. The container is then completely sealed under an argon atmosphere. The container is set in a planetary ball mill P-7 (trade name, manufactured by Fritsch), and mechanical milling is performed at a temperature of 25°C and a rotation speed of 510 rpm for 20 hours to obtain 6.20 g of yellow powder sulfide-based inorganic solid electrolyte (Li-P-S glass, hereinafter sometimes referred to as LPS). The particle size (volume average particle size) of this LPS is 15 μm.

[0224] <Particle Size Adjustment> The particle size of the obtained LPS is adjusted by wet dispersion under the following conditions. (Particle Size Adjustment Example A1) 160 zirconia beads with a diameter of 5 mm are placed in a 45 mL zirconia container (manufactured by Fritsch), and 4.0 g of synthesized LPS and 6.0 g of mesitylene as an organic solvent are added. Then the container is set in a planetary ball mill P-7, and wet dispersion is performed at 300 rpm for 30 minutes to obtain LPS-1 with a particle size (volume average particle size) of 1.0 μm. (Particle Size Adjustment Examples A2 and A3) Except for changing the rotation speed of the wet dispersion to 250 rpm or 100 rpm in particle size adjustment example A1, LPS-2 with a particle size of 2.0 μm and LPS-3 with a particle size of 5.0 μm are obtained in the same manner as in particle size adjustment example A1.

[0225] [Example 1 and Comparative Example 1] <Example 1-1> Add 7.5 g of positive electrode active material (particle size 5 μm), 2.1 g of inorganic solid electrolyte, 0.3 g of conductive additive (acetylene black, particle size 35 nm, manufactured by Denka Co., Ltd.), 0.1 g of binder A-1, and 2.5 g of mesitylene to a container and mix using a rotary-orbit mixer at a rotational speed of 2000 rpm and an orbital speed of 800 rpm for 20 minutes to prepare positive electrode composition 1-1 with a slurry solid content of 80% by mass. The prepared positive electrode composition 1-1 is applied to a 20 μm thick aluminum foil using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.), heated at 120°C for 1 hour, and then dried in a vacuum dryer AVO-200NS (product name, manufactured by AS ONE Corporation) at 120°C for 2 hours to dry the positive electrode composition 1-1 (remove the dispersion medium). Thus, the amount of the mixture is 26 mg / cm³. ２ A positive electrode sheet 1-1 for an all-solid-state secondary battery having a positive electrode active material layer is prepared. Here, the amount of composite material means the total mass of the inorganic solid electrolyte, positive electrode active material, and conductive additive per unit area.

[0226] Using the above-mentioned positive electrode sheet 1-1 for all-solid-state secondary batteries, an all-solid-state secondary battery 1-1 is manufactured as follows. The positive electrode sheet 1-1 for all-solid-state secondary batteries is punched out into a disc shape with a diameter of 10 mmφ and placed in a 10 mmφ polyethylene terephthalate (PET) cylinder. 60 mg of LPS-3 with adjusted particle size is placed on the surface of the positive electrode active material layer inside the cylinder, and 10 mmφ stainless steel rods are inserted from the openings at both ends of the cylinder. The positive electrode current collector side of the positive electrode sheet 1-1 for all-solid-state secondary batteries and the LPS-3 are pressurized with the stainless steel rods at a pressure of 350 MPa to form a solid electrolyte layer. Then, the stainless steel rods placed on the solid electrolyte layer side are temporarily removed, and a disc-shaped indium (In) sheet (thickness 20 μm) with a diameter of 9 mmφ and a disc-shaped lithium (Li) sheet (thickness 20 μm) with a diameter of 9 mmφ are inserted on top of the solid electrolyte layer inside the cylinder in this order. The removed SUS rod is reinserted into the cylinder and fixed in place under a pressure of 50 MPa. In this way, an all-solid-state secondary battery (half-cell) 1-1 having the following configuration is manufactured: aluminum foil (thickness 20 μm) - positive electrode active material layer (thickness 100 μm) - sulfide-based inorganic solid electrolyte layer (thickness 400 μm) - negative electrode active material layer (In / Li sheet, thickness 30 μm).

[0227] <Examples 1-2 to 1-7 and Comparative Examples 1-1 to 1-2> Positive electrode compositions 1-2 to 1-7 and c1-1 to c1-2 are prepared in the same manner as in Example 1-1, except that the binder solution shown in the "Polymer" column of Table 1 is used instead of binder solution A-1. Then, positive electrode sheets 1-2 to 1-7 and c1-1 to c1-2 for all-solid-state secondary batteries are prepared in the same manner as in Example 1-1, except that positive electrode compositions 1-2 to 1-7 and c1-1 to c1-2 are used instead of positive electrode composition 1-1. All-solid-state secondary batteries 1-2 to 1-7 and c1-1 to c1-2 are manufactured in the same manner as in Example 1-1.

[0228] <Evaluation 1: Evaluation of the dispersibility of the positive electrode composition> The dispersibility of the positive electrode composition prepared separately using the components used in the preparation of each electrode composition was evaluated in terms of viscosity and electrode manufacturability as described below, and the results are shown in Table 1. Specifically, 7.5 g of positive electrode active material, 2.1 g of inorganic solid electrolyte, 0.3 g of conductive additive, 0.1 g of binder, and 2.5 g of mesitylene were added to a 60 mL ointment container, and a positive electrode composition (composition for Evaluation 1) with a slurry solid content of 80% by mass was prepared using a rotary-orbit mixer at a rotation of 2000 rpm and a revolution of 800 rpm for 20 minutes. The viscosity of each positive electrode composition (composition for Evaluation 1) was measured using an E-type viscometer (TV-30 (product name), manufactured by Toki Sangyo Co., Ltd.) and measured at 25°C with a shear rate of 10 / s. In this test, the lower the viscosity, the more uniformly the positive electrode composition is dispersed, and it is judged to be a good slurry, with a viscosity of 2000 cP or less being considered to have excellent dispersibility. Furthermore, each positive electrode composition (composition for evaluation 1) is applied to a 20 μm thick aluminum foil using a doctor blade with a coating thickness of 300 μm, and dried on a hot plate at 120°C for 30 minutes to form a positive electrode active material layer. In this way, a positive electrode sheet for an all-solid-state secondary battery is manufactured. The average height surface roughness Rc of the roughness curve elements of each positive electrode sheet is measured using a roughness measuring instrument. The average height surface roughness Rc is measured in accordance with Japanese Industrial Standard (JIS) B 0601:2013. If the measured surface roughness Rc is less than 10 μm, it is determined that the electrode (active material layer) can be manufactured and is indicated as "○" in Table 1, and if the surface roughness Rc is 10 μm or more, it is indicated as "×". Note that the surface roughness Rc in Example 1-1 is 5 μm or less.

[0229] <Evaluation 2: Evaluation of 180° Peel Strength> Dissolve 1 g of the polymer binder used in the preparation of each cathode composition in 9 g of mesitylene to prepare 10 g of a binder solution with a solid content of 10% by mass. Apply the obtained binder solution to a 20 μm thick aluminum foil (150 mm × 200 mm) using a doctor blade with a coating thickness of 150 μm, and dry it on a hot plate at 120°C for 30 minutes to obtain aluminum foil having a coated and dried binder layer (binder layer). Cut this aluminum foil into strips of 25 mm × 70 mm, and place a 20 μm thick aluminum foil strip cut into 20 mm × 150 mm strips onto the surface of the binder layer at a surface pressure of 0.5 N / m ２ The aluminum foils were bonded together to create an evaluation sample. Here, a 25 mm x 70 mm aluminum foil and a 20 mm x 150 mm aluminum foil were bonded together so that the center lines connecting the centers of the shorter sides coincided. Using an IMADA force gauge, a 180° peel test was performed by peeling the 20 mm x 150 mm strip of aluminum foil from the binder layer at a peel angle of 180° in a direction parallel to the center line at a sweep speed of 100 mm / min. The 180° peel strength was defined as the average strength when the displacement was between 20 and 50 mm. The results are shown in Table 1. In this test, a 180° peel strength of 250 N / m or higher was considered acceptable. The 180° peel strength of polymer A-1 in Example 1-1 was 280 N / m.

[0230] <Evaluation 3: Adhesion (Handling) between Current Collector and Positive Electrode Active Material Layer> A test sheet cut from the positive electrode sheet for all-solid-state secondary batteries prepared in <Evaluation 1: Dispersibility Evaluation of Positive Electrode Composition> above into a rectangle 2 cm wide x 15 cm long is bent using a cylindrical mandrel tester (product code 056, Allgood Co., Ltd.) in accordance with Japanese Industrial Standard (JIS) K5600-5-1 (Bending resistance (test using cylindrical mandrel: type 2 test apparatus), same test as international standard (ISO) 1519). The test sheet is set with the positive electrode active material layer on the opposite side from the mandrel (aluminum foil on the mandrel side) and the width direction parallel to the axis of the mandrel. The test was conducted by changing the mandrel diameter in the following order: 32 mm, 25 mm, 21 mm, 20 mm, 19 mm, 16 mm, 13 mm, 12 mm, 10 mm, 8 mm, 6 mm, 5 mm, 4 mm, 3 mm, and 2 mm. The minimum diameter at which the positive electrode active material layer did not peel off from the aluminum foil was measured and evaluated. The results are shown in Table 1. In this test, a smaller minimum diameter indicates stronger adhesion between the positive electrode active material layer and the current collector. A minimum diameter of 20 mm or less indicates good adhesion and excellent handling. In Example 1-1, the minimum diameter was Φ19 mm.

[0231] <Evaluation 4: Evaluation of Cycle Characteristics> For all-solid-state secondary batteries (half-cells) manufactured in each example and comparative example, rate characteristic tests will be performed using the charge / discharge evaluation device TOSCAT-3000 (product name, manufactured by Toyo System Co., Ltd.) to evaluate the cycle characteristics. Specifically, each all-solid-state secondary battery will be tested at a current density of 1 mA / cm² in an environment of 40°C. ２ Charge the battery until the voltage reaches 3.68V, then set the current density to 1mA / cm². ２One cycle is defined as discharging the battery until the voltage reaches 1.88V, and this is performed for 200 cycles. The ratio of the discharge capacity in the first cycle to the discharge capacity in the 200th cycle is calculated using the following formula, and the cycle characteristics of the all-solid-state secondary battery are evaluated by applying the following evaluation criteria to the discharge capacity ratio (43%) of the all-solid-state secondary battery in Comparative Example 1-1 as the baseline. The results are shown in Table 1. Discharge capacity ratio (%): [Discharge capacity in the 200th cycle / Discharge capacity in the first cycle] × 100 (Evaluation criteria) A: Above baseline + 10% ≤ Discharge capacity ratio B: Above baseline + 7% ≤ Discharge capacity ratio < Above baseline + 10% C: Above baseline + 4% ≤ Discharge capacity ratio < Above baseline + 7% D: Above baseline - 5% ≤ Discharge capacity ratio < Above baseline + 4% E: Discharge capacity ratio < Above baseline - 5%

[0232]

[0233] <Explanation of symbols> NCM-1: LiNi ０．５ Co ０．２ Mn ０．３ O ２ (NCM523), Particle size (volume average particle size) 5 μm LPS-1 measured by the above method: LPS-1 with a particle size of 1.0 μm

[0234] [Examples 2 and Comparative Examples 2] <Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-3> Except that, in Example 1-1, instead of the positive electrode active material, inorganic solid electrolyte, conductive additive, binder solution A-1 and mesitylene, the binder solution shown in the "Polymer (Binder Solution)" column of Table 2, the positive electrode active material, conductive additive (acetylene black, particle size 35 nm, manufactured by Denka Co., Ltd.), and butyl butyrate (BB) as a dispersion medium are mixed in the mass ratios shown in the "Amount Mixed" column of Table 2 and the values ​​shown in the "Solid Content Concentration" column of Table 2, the positive electrode compositions 2-1 to 2-8 and c2-1 to c2-3 are prepared in the same manner as in Example 1-1, except that the binder solution shown in the "Polymer (Binder Solution)" column of Table 2, the positive electrode active material, conductive additive (acetylene black, particle size 35 nm, manufactured by Denka Co., Ltd.), and butyl butyrate (BB) as a dispersion medium are mixed in the mass ratios shown in the "Amount Mixed" column of Table 2 and the values ​​shown in the "Solid Content Concentration" column of Table 2. Next, in the same manner as in Example 1-1, except that positive electrode compositions 2-1 to 2-8 and c2-1 to c2-3 are used instead of positive electrode composition 1-1, all-solid-state secondary battery positive electrode sheets 2-1 to 2-8 and c2-1 to c2-3 are manufactured, and all-solid-state secondary batteries 2-1 to 2-8 and c2-1 to c2-3 are manufactured.

[0235] <Evaluation 1 to Evaluation 4> Each positive electrode composition prepared in Example 2 and Comparative Example 2, the positive electrode sheet for all-solid-state secondary batteries produced, and the all-solid-state secondary battery manufactured will be evaluated in the same manner as Evaluation 1 to Evaluation 4 in Example 1. The results are shown in Table 2. However, in Evaluation 1, the "Evaluation 1 composition," which is prepared separately by mixing the components used in each of Example 2 and Comparative Example 2 in the mixing ratios described in Evaluation 1, will be used as the subject of evaluation. Furthermore, in Evaluation 3, the positive electrode sheet for all-solid-state secondary batteries manufactured using the Evaluation 1 composition prepared in Evaluation 1 will be used as the subject of evaluation. The standard for Evaluation 4 will be Comparative Example 2-1.

[0236]

[0237] <Explanation of symbols> NCM-1: LiNi ０．５ Co ０．２ Mn ０．３ O ２ (NCM523), Particle size (volume average particle size) 5 μm according to the above measurement method. LPS-2: LPS-2 with a particle size of 2.0 μm. BB: Butyl butyrate (CAS No. 109-21-7)

[0238] [Example 3 and Comparative Example 3] <Examples 3-1 to 3-5 and Comparative Examples 3-1 to 3-2> Except that, in Example 1-1, instead of the positive electrode active material, inorganic solid electrolyte, conductive additive, binder solution A-1, and mesitylene, the binder solution shown in the "Polymer (Binder Solution)" column of Table 3, the positive electrode active material, conductive additive (VGCF-H, vapor-grown carbon fiber, average short axis diameter 0.15 μm, average long axis length 4.8 μm, ratio [average long axis length / average short axis diameter] 32, manufactured by Resonaq Corporation), and mesitylene as a dispersion medium are mixed in the same manner as in Example 1-1, in the mass ratios shown in the "Amount Mixed" column of Table 3 and the values ​​shown in the "Solid Content Concentration" column of Table 3. Next, in the same manner as in Example 1-1, except that positive electrode compositions 3-1 to 3-5 and c3-1 to c3-2 are used instead of positive electrode composition 1-1, all-solid-state secondary battery positive electrode sheets 3-1 to 3-5 and c3-1 to c3-2 are manufactured, and all-solid-state secondary batteries 3-1 to 3-5 and c3-1 to c3-2 are manufactured.

[0239] <Evaluation 1 to Evaluation 4> Each positive electrode composition prepared in Example 3 and Comparative Example 3, the positive electrode sheet for all-solid-state secondary batteries produced, and the all-solid-state secondary battery manufactured will be evaluated in the same manner as Evaluation 1 to Evaluation 4 in Example 1. The results are shown in Table 3. However, in Evaluation 1, the "Evaluation 1 composition," which is prepared separately by mixing the components used in each Example 3 and Comparative Example 3 in the mixing ratios described in Evaluation 1, will be used as the subject of evaluation. In Evaluation 3, the positive electrode sheet for all-solid-state secondary batteries manufactured using the Evaluation 1 composition prepared in Evaluation 1 will be used as the subject of evaluation. The standard for Evaluation 4 will be Comparative Example 3-1.

[0240]

[0241] <Explanation of symbols> NCM-1: LiNi ０．５ Co ０．２ Mn ０．３ O ２ (NCM523), Particle size (volume average particle size) 5 μm LPS-1 measured by the above method: LPS-1 with a particle size of 1.0 μm

[0242] [Example 4 and Comparative Example 4] <Examples 4-1 to 4-4 and Comparative Examples 4-1 to 4-2> Except that, in Example 1-1, instead of the positive electrode active material, inorganic solid electrolyte, conductive additive, binder solution A-1, and mesitylene, the binder solution shown in the "Polymer (Binder Solution)" column of Table 4, the positive electrode active material, conductive additive (acetylene black, particle size 35 nm, manufactured by Denka Co., Ltd.), and mesitylene as a dispersion medium are mixed in the mass ratios shown in the "Amount Mixed" column of Table 4 and the values ​​shown in the "Solid Content Concentration" column of Table 4, the same procedure as in Example 1-1, to prepare positive electrode compositions 4-1 to 4-4 and c4-1 to c4-2. Next, in the same manner as in Example 1-1, except that positive electrode compositions 4-1 to 4-4 and c4-1 to c4-2 are used instead of positive electrode composition 1-1, all-solid-state secondary battery positive electrode sheets 4-1 to 4-4 and c4-1 to c4-2 are manufactured, and all-solid-state secondary batteries 4-1 to 4-4 and c4-1 to c4-2 are manufactured.

[0243] <Evaluation 1 to Evaluation 4> Each positive electrode composition prepared in Example 4 and Comparative Example 4, the positive electrode sheet for all-solid-state secondary batteries produced, and the all-solid-state secondary battery manufactured will be evaluated in the same manner as Evaluation 1 to Evaluation 4 in Example 1. The results are shown in Table 4. However, in Evaluation 1, the "Evaluation 1 composition," which is prepared separately by mixing the components used in each Example 4 and Comparative Example 4 in the mixing ratios described in Evaluation 1, will be used as the subject of evaluation. Furthermore, in Evaluation 3, the positive electrode sheet for all-solid-state secondary batteries manufactured using the Evaluation 1 composition prepared in Evaluation 1 will be used as the subject of evaluation. The standard for Evaluation 4 will be Comparative Example 4-1.

[0244]

[0245] <Explanation of symbols> NCM-2: LiNi ０．６ Co ０．２ Mn ０．２ O ２ (NCM622), Particle size (volume average particle size) 8 μm LPS-3 measured by the above method: LPS-3 with a particle size of 5 μm

[0246] The results shown in Tables 1 to 4 indicate the following: Even when inorganic solid electrolyte, electrode active material, conductive additive, binder (polymer binder), and dispersion medium are contained in specific amounts, the comparative positive electrode composition in which the polymer binder does not contain 30 to 99.9% by mass of the constituent unit represented by formula A, and the comparative positive electrode composition in which the polymer binder has a 180° peel strength with respect to the current collector of less than 250 N / m, both do not exhibit sufficient dispersibility. Furthermore, the comparative positive electrode composition cannot be used to produce a positive electrode sheet in which the current collector and the positive electrode active material layer are in close contact with sufficient adhesion, nor an all-solid-state secondary battery exhibiting sufficient cycle characteristics. In contrast, the positive electrode compositions of the examples, which contain an inorganic solid electrolyte, electrode active material, conductive additive, binder (polymer binder), and dispersion medium in specific amounts, and in which the binder contains a polymer binder containing 30 to 99.9% by mass of the constituent units represented by the above formula A, and in which this polymer binder exhibits a 180° peel strength of 250 N / m or more against the current collector, all exhibit excellent dispersibility even when the solid content concentration is increased. Furthermore, all of the positive electrode compositions of the examples exhibit strong adhesion to the current collector even when the active material layer is made thick, enabling the production of positive electrode sheets for all-solid-state secondary batteries that achieve excellent handling. Therefore, positive electrode sheets for all-solid-state secondary batteries produced using the positive electrode compositions of the examples can be suitably applied to continuous manufacturing methods such as the roll-to-roll method, which are widely used as industrial manufacturing methods. Moreover, all of the positive electrode compositions of the examples exhibit excellent cycle characteristics, and enable the production of all-solid-state secondary batteries that can also improve energy density by making the electrode active material layer thicker. Thus, the electrode composition of the present invention can achieve improved productivity and battery performance for all-solid-state secondary batteries.

[0247] Although we have described the present invention along with its embodiments, we do not intend to limit our invention in any detail of the description unless specifically designated, and we believe that it should be interpreted broadly without contradicting the spirit and scope of the invention as set forth in the appended claims.

[0248] This application claims priority based on Japanese Patent Application No. 2025-055614, filed in Japan on 28 March 2025, the contents of which are incorporated herein by reference as part of this specification.

[0249] 1. Negative electrode current collector 2. Negative electrode active material layer 3. Solid electrolyte layer 4. Positive electrode active material layer 5. Positive electrode current collector 6. Working part 10. All-solid-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

An electrode composition comprising an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, an electrode active material, a conductive additive, a binder, and a dispersion medium, The content of the inorganic solid electrolyte is 10 to 35% by mass of the solid content of the electrode composition, the content of the electrode active material is 60 to 88% by mass, the content of the conductive additive is 0.1 to 5% by mass, and the content of the binder is 0.2 to 5% by mass. The binder comprises a polymer containing 30 to 99.9% by mass of a constituent unit represented by the following formula A, and includes a polymer binder that dissolves in the dispersion medium. The polymer binder is an electrode composition having a 180° peel strength with respect to the current collector of 250 N / m or more. In the above formula A, R １ R represents a hydrogen atom or a methyl group. ２ This indicates an alkyl group having 6 to 24 carbon atoms, or a group containing a siloxane bond. 　 The electrode composition according to claim 1, wherein the polymer contains 30 to 99.9% by mass of the constituent unit represented by formula A, and contains 0.1 to 65% by mass of at least one of the constituent unit represented by the following formula B, the constituent unit represented by the following formula C, and the constituent unit represented by the following formula D. In the above formula B, R ３ R represents a hydrogen atom or a methyl group. ４ and R ５ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ４ and R ５ They may be combined. 　 In the above formula C, R ６ and R ７ each represent a hydrogen atom or a methyl group, R ８ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, R ９ and R １０ each represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and R ９ and R １０ may be bonded to each other. 　 In the above formula D, R １１ and R １２ R represents a hydrogen atom or a methyl group. １３ This represents a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, or a phenyl group. 　 The adsorption rate A of the polymer binder to the inorganic solid electrolyte in the dispersion medium. ＳＥ The electrode composition according to claim 1, wherein the amount is greater than 4% and less than or equal to 45%. 　 The electrode composition according to claim 1, wherein the 180° peel strength is 350 N / m or more. 　 Adsorption rate A ＳＥ The electrode composition according to claim 1, wherein the amount is greater than 15% and less than or equal to 40%. 　 The electrode composition according to claim 1, wherein the polymer contains 30 to 82% by mass of a constituent unit represented by the following formula A1 and 18 to 45% by mass of a constituent unit represented by the following formula B. In the above formula A1, R １ R represents a hydrogen atom or a methyl group. ２ This represents an alkyl group having 6 to 24 carbon atoms. 　 In the above formula B, R ３ R represents a hydrogen atom or a methyl group. ４ and R ５ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ４ and R ５ They may be combined. 　 The electrode composition according to claim 1, wherein the polymer contains 45 to 99% by mass of a constituent unit represented by the following formula A2 and 1 to 50% by mass of a constituent unit represented by the following formula B. In the above formula A2, R １ R represents a hydrogen atom or a methyl group. ２ This indicates a group containing a siloxane bond. 　 In the above formula B, R ３ R represents a hydrogen atom or a methyl group. ４ and R ５ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ４ and R ５ They may be combined. 　 The electrode composition according to claim 1, wherein the polymer contains 50 to 99.5% by mass of a constituent unit represented by the following formula A, and contains 0.5 to 40% by mass of at least one of a constituent unit represented by the following formula C and a constituent unit represented by the following formula D. In the above formula A, R １ R represents a hydrogen atom or a methyl group. ２ This indicates an alkyl group having 6 to 24 carbon atoms, or a group containing a siloxane bond. 　 In the above formula C, R ６ and R ７ R represents a hydrogen atom or a methyl group. ８ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ９ and R １０ R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ９ and R １０ They may be combined. 　 In the above formula D, R １１ and R １２ R represents a hydrogen atom or a methyl group. １３ This represents a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, or a phenyl group. 　 An electrode sheet for an all-solid-state secondary battery having an electrode active material layer composed of the electrode composition according to any one of claims 1 to 8. 　 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, All-solid-state secondary battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer is a layer formed using the electrode composition described in any one of claims 1 to 8. 　 A method for manufacturing an electrode sheet for an all-solid-state secondary battery, comprising forming a film of the electrode composition described in any one of claims 1 to 8. 　 A method for manufacturing an all-solid-state secondary battery, comprising manufacturing an all-solid-state secondary battery via the manufacturing method described in claim 11.

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