Electrode composition, electrode sheet for all-solid-state secondary battery, and all-solid-state secondary battery, and method for manufacturing the electrode sheet for all-solid-state secondary battery and all-solid-state secondary battery.

Abstract

The present invention provides: an electrode composition which contains an inorganic solid electrolyte, an active material, a conductive assistant, a polymer binder and a dispersion medium, while satisfying the conditions (1) to (4) described below; an electrode sheet for all-solid-state secondary batteries; an all-solid-state secondary battery; a method for producing an electrode sheet for all-solid-state secondary batteries; and a method for producing an all-solid-state secondary battery. (1) The polymer binder is dissolved in the dispersion medium. (2) The adsorption rate of the polymer binder with respect to the conductive assistant is more than 0% but not more than 50%. (3) The mass average molecular weight of the polymer that constitutes the polymer binder is 6,000 or more. (4) The average particle diameter of the conductive assistant in an active material layer that is formed of the electrode composition is less than 1.0 µm.

Description

[Technical Field]

[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 the electrode sheet for an all-solid-state secondary battery and the all-solid-state secondary battery. [Background technology]

[0002] A secondary battery is a rechargeable battery that has a negative electrode, a positive electrode, and an electrolyte sandwiched between the negative and positive electrodes, and enables charging and discharging by moving specific metal ions, such as lithium ions, back and forth between the two electrodes. Non-aqueous electrolyte secondary batteries using organic electrolytes are widely used as such secondary batteries, but research is underway on electrodes and their forming materials with the aim of further improving battery performance such as rate characteristics. For example, Patent Document 1 describes a slurry containing an electrode active material, a conductive material, and a dispersant consisting of an ionic surfactant. In this slurry, it is stated that the conductive material uniformly coats the surface of the electrode active material by using a dispersant consisting of an ionic surfactant. Patent Document 2 describes a solution for forming a coated positive electrode active material, which is a solution obtained by mixing a conductive material with a coating polymer compound solution containing positive electrode active material powder, a coating polymer compound, and isopropanol. However, non-aqueous electrolyte secondary batteries using organic electrolytes are prone to leakage, and short circuits can easily occur inside the battery due to overcharging or over-discharging. Therefore, further improvements in safety and reliability are required.

[0003] Under these circumstances, all-solid-state secondary batteries, which use inorganic solid electrolytes instead of organic electrolytes, are attracting attention. In these all-solid-state secondary batteries, the negative electrode, electrolyte, and positive electrode are all made of solid material, which can greatly improve the safety and reliability of batteries using organic electrolytes. It is also said that a longer lifespan is possible. Furthermore, all-solid-state secondary batteries can be constructed by directly arranging the electrodes and electrolyte in series. Therefore, it is possible to achieve a higher energy density compared to non-aqueous electrolyte secondary batteries using organic electrolytes, and applications in electric vehicles and large-scale storage batteries are expected.

[0004] Whether it is a non-aqueous electrolyte secondary battery or an all-solid-state secondary battery, the constituent layers of a secondary battery are usually formed using a slurry composition in which the materials forming the constituent layers are dispersed or dissolved in a dispersion medium, as described in Patent Documents 1 and 2. However, in recent years, inorganic solid electrolytes, particularly oxide-based and sulfide-based inorganic solid electrolytes, have attracted attention as electrolyte materials with high ionic conductivity approaching that of organic electrolytes, as materials for forming the constituent layers (active material layer, solid electrolyte layer, etc.) of all-solid-state secondary batteries. Research and development of all-solid-state secondary batteries that take advantage of the properties of these inorganic solid electrolytes are rapidly progressing. However, regarding materials (electrode compositions) containing the above-mentioned inorganic solid electrolyte, active material, and conductive additives as materials for forming the active material layer of all-solid-state secondary batteries (active material layer forming materials), Patent Documents 1 and 2 do not discuss them at all. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-073687 [Patent Document 2] Japanese Patent Publication No. 2017-188455 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Because the constituent layers of an all-solid-state secondary battery are formed from solid particles (inorganic solid electrolyte, active material, conductive additive, etc.), the interfacial contact state between the solid particles, and furthermore, the interfacial contact state between the solid particles and the current collector, is constrained, making it easy for interfacial resistance to increase. This increase in interfacial resistance not only increases the battery resistance (decrease in ionic conductivity) of the all-solid-state secondary battery, but also causes a decrease in the cycle characteristics of the all-solid-state secondary battery. The increase in resistance, which is a factor in the deterioration of battery performance, is caused not only by the interfacial contact state of solid particles, but also by the non-uniform distribution (arrangement) of solid particles within the constituent layers. Therefore, when forming constituent layers with a constituent layer forming material, the constituent layer forming material is required to have the property (dispersion stability) to stably maintain the dispersibility of solid particles immediately after preparation. Furthermore, in recent years, from the perspective of reducing environmental impact and manufacturing costs, the use of high-concentration compositions (concentrated slurries) with increased solid content as constituent layer-forming materials has been considered. However, as the solid content concentration of a composition increases, the properties of the composition generally deteriorate significantly. The same applies to dispersion stability, etc., and it is not easy to achieve the required dispersion stability, etc., in high-concentration compositions.

[0007] The present invention aims to provide an electrode composition that exhibits excellent dispersion stability even when the solid content concentration is increased, and which, when used as an active material layer forming material for an all-solid-state secondary battery, can suppress the increase in battery resistance and achieve excellent cycle characteristics. Furthermore, the present invention aims to provide an electrode sheet for an all-solid-state secondary battery and an all-solid-state secondary battery using this electrode composition, as well as a method for manufacturing the electrode sheet for an all-solid-state secondary battery and an all-solid-state secondary battery. [Means for solving the problem]

[0008] The inventors diligently studied electrode compositions and found that while some improvement in dispersion stability can be expected for inorganic solid electrolytes through improvements to polymer binders, etc., in electrode compositions where conductive additives with poor dispersibility in the dispersion medium coexist, comprehensively improving the behavior of the polymer binder with respect to the conductive additive in the dispersion medium leads to improved dispersion stability. Based on this idea, the inventors further investigated and found that by forming the polymer binder used in combination with solid particles from a polymer with a specific molecular weight, imparting the property of dissolving in the dispersion medium, and exhibiting appropriate affinity to disperse the conductive additive as particles of a specific size in the dispersion medium, it is possible to achieve excellent dispersion stability in the electrode composition even when the solid content concentration is increased. Furthermore, they found that by using this electrode composition as an active material layer forming material, it is possible to manufacture an all-solid-state secondary battery that can suppress the increase in battery resistance and achieve excellent cycle characteristics. This invention was completed after further consideration based on these findings.

[0009] In other words, the above problems were solved by the following means. <1> An electrode composition comprising 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) Conductive additive (C) in the dispersion medium (D) of polymer binder (B) Adsorption rate for A) [A CA The percentage must be greater than 0% and less than or equal to 50%. (3) The mass-average molecular weight of the polymer constituting the polymer binder (B) is It must be 6,000 or more. (4) The ratio of conductive additives (CA) present in the active material layer formed by the electrode composition The uniform particle size must be less than 1.0 μm. <2> Adsorption rate [A CA] is between 5% and 30%. <1> The electrode composition described above. <3> Adsorption rate of polymer binder (B) to inorganic solid electrolyte (SE) in dispersion medium (D) [A SE ] is 45% or less. <1> or <2> The electrode composition described above. <4> The mass-average molecular weight is between 10,000 and 700,000. <1> ~ <3> An electrode composition as described in any one of the following. <5> The difference ΔSP between the SP value of the dispersion medium (D) and the SP value of the polymer constituting the polymer binder (B) is 3.0 MPa. 1 / 2 The following is: <1> ~ <4> An electrode composition as described in any one of the following. <6> The polymer forming the polymer binder (B) includes a component having a functional group selected from the following functional group group (a). <1> ~ <5> An electrode composition as described in any one of the following. <Functional group group (a)> Hydroxyl group, amino group, carboxyl group, sulfo group, phosphate group, phosphonic acid group, sulfanyl group, ether bond, imino group, ester bond, amide bond, urethane bond, urea bond, heterocyclic group, aryl group, carboxylic anhydride group <7> The inorganic solid electrolyte (SE) is a sulfide-based inorganic solid electrolyte. <1> ~ <6> An electrode composition as described in any one of the following. <8> the above <1> ~ <7> An electrode sheet for an all-solid-state secondary battery having an active material layer composed of any one of the electrode compositions described in one of the above. <9> The average particle size of the conductive additive (CA) in the active material layer is 0.5 μm or less. <8> Electrode sheets for all-solid-state secondary batteries as described above. <10> The electronic conductivity of the active material layer is 30 mS / cm or higher. <8> or <9> Electrode sheets for all-solid-state secondary batteries as described above. <11> 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, At least one layer of the positive electrode active material layer and the negative electrode active material layer <1> ~ <7> An all-solid-state secondary battery having an active material layer composed of an electrode composition described in any one of the above. <12> the above <1> ~ <7> 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 the above. <13> the 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 above. [Effects of the Invention]

[0010] The present invention provides an electrode composition that exhibits excellent dispersion stability even when the solid content concentration is increased, and by using it as an active material layer forming material for all-solid-state secondary batteries, it can provide an electrode composition that can suppress the increase in battery resistance and achieve excellent cycle characteristics. Furthermore, the present invention can provide an electrode sheet for all-solid-state secondary batteries and an all-solid-state secondary battery having an active material layer composed of this electrode composition. Moreover, the present invention can provide a method for manufacturing an electrode sheet for all-solid-state secondary batteries and an all-solid-state secondary battery using this electrode composition. The above and other features and advantages of the present invention will become more apparent from the following description, with reference to the accompanying drawings as appropriate. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic longitudinal cross-sectional view showing an all-solid-state secondary battery according to a preferred embodiment of the present invention. [Modes for carrying out the invention]

[0012] In this invention, a numerical range represented using "~" means a range that includes the values ​​written before and after "~" as the lower and upper limits. In this invention, when multiple numerical ranges are set and explained for the content of components, physical properties, etc., the upper and lower limits that form the numerical range are not limited to the specific combinations written before and after "~" as a specific numerical range, but can be numerical ranges that are appropriately combined from the upper and lower limits of each numerical range. In this invention, the designation of a compound (for example, when referring to it with "compound" at the end) includes not only the compound itself, but also its salts and ions. It also includes derivatives in which parts have been altered, such as by introducing substituents, to the extent that the effects of this invention are not impaired. In this invention, (meth)acrylic means either or both acrylic and methacrylic. The same applies to (meth)acrylate. In the present invention, substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) that are not explicitly stated as substituted or unsubstituted may have appropriate substituents. Therefore, even when simply referred to as a YYY group in the present invention, this YYY group includes not only the unsubstituted form but also the form with substituents. The same applies to compounds that are not explicitly stated as substituted or unsubstituted. A preferred substituent is, for example, substituent Z, which will be described later. In the present invention, when there are multiple substituents indicated by specific symbols, or when multiple substituents are specified simultaneously or alternatively, it means that each substituent may be the same as or different from the others. Furthermore, even if not specifically stated otherwise, when multiple substituents are adjacent to each other, they may be linked to each other or fused to form a ring. In this invention, "polymer" means a polymer and is synonymous with so-called high-molecular-weight compounds. Furthermore, "polymer binder" (also simply called "binder") means a binder composed of polymers and includes both the polymer itself and binders composed (formed) containing polymers.

[0013] In the present invention, a composition containing an inorganic solid electrolyte, an active material, a conductive additive, and a polymer binder, used as a material for forming the active material layer of an all-solid-state secondary battery (active material layer forming material), is called an electrode composition (also called an electrode composition for all-solid-state secondary batteries). On the other hand, a composition containing an inorganic solid electrolyte and a polymer binder as appropriate, used as a material for forming the solid electrolyte layer of an all-solid-state secondary battery, is called an inorganic solid electrolyte-containing composition, and this composition usually does not contain an active material and a conductive additive. In the present invention, the electrode composition includes a positive electrode composition containing a positive electrode active material and a negative electrode composition containing a negative electrode active material. Therefore, either or both of the positive electrode composition and the negative electrode composition may be simply referred to as the electrode composition, and either or both of the positive electrode active material layer and the negative electrode active material layer may be simply referred to as the active material layer or electrode active material layer. Furthermore, either or both of the positive electrode active material and the negative electrode active material may be simply referred to as the active material or electrode active material.

[0014] [Electrode composition] The electrode composition of the present invention contains 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 satisfies the conditions (1) to (4) described below. This electrode composition can maintain its excellent dispersibility immediately after preparation even when the solid content concentration is increased, and can stably maintain this dispersibility over time (excellent dispersion stability). By using this electrode composition as an active material layer forming material, an active material layer satisfying the physical properties described below can be formed, enabling the realization of an all-solid-state secondary battery that suppresses the increase in battery resistance and exhibits excellent cycle characteristics.

[0015] The exact reasons are not yet clear, but they can be considered as follows: Because the polymer binder (B) is composed of polymers with high molecular weights within a specific range (condition (3)) and is dissolved in the dispersion medium (D) (condition (1)), the molecular chains of the polymer binder (B) spread out widely in the dispersion medium (D). When such a polymer binder (B) exhibits appropriate adsorption (affinity) to the conductive additive (CA) (condition (2)), in the dispersion medium (D) and during the film formation process of the electrode composition, the polymer binder suppresses excessive adsorption to solid particles, especially the conductive additive (CA), while effectively suppressing (re)aggregation or sedimentation by causing the adsorbed solid particles to repel each other, allowing the conductive additive to exist as particles with an average particle size of 1 μm or less (condition (4)). Moreover, during the film formation process of the electrode composition, direct contact between solid particles in the active material layer becomes possible, allowing for the sufficient construction of conduction paths (electron conduction paths, ion conduction paths) containing the conductive additive (CA). In this way, the interfacial resistance between solid particles, and furthermore, the increase in resistance of the active material layer, can be suppressed. By forming an active material layer using such an electrode composition with excellent dispersion stability, direct contact between solid particles can be ensured while suppressing uneven distribution of solid particles and aggregation of conductive additives (CAs). In particular, the dispersibility of conductive additives (CAs), which are responsible for electronic conductivity, can be improved (uneven distribution of conductive additives (CAs) within the active material layer can be suppressed), and it is believed that excellent electronic conductivity (construction of sufficient conductive paths throughout the entire active material layer) can be achieved. Therefore, all-solid-state secondary batteries incorporating this active material layer exhibit excellent cycle characteristics by keeping battery resistance low, preventing overcurrents from occurring during charging and discharging, and preventing degradation of solid particles.

[0016] In the electrode composition of the present invention, the polymer binder (B) is thought to function by adsorbing at least the conductive additive (CA) and, as appropriate, also adsorbing to the inorganic solid electrolyte (SE) and active material (AC), and interposing between solid particles, thereby dispersing solid particles such as the conductive additive (CA) in the dispersion medium (D). Here, the adsorption of the polymer binder (B) to the solid particles is not particularly limited, but includes not only physical adsorption but also chemical adsorption (adsorption by chemical bond formation, adsorption by electron transfer, etc.). On the other hand, the polymer binder (B) functions as a binder that binds solid particles together in the active material layer. It may also function as a binder that binds the current collector to the solid particles.

[0017] As described above, the electrode composition of the present invention satisfies the following conditions (1) to (4). Each of these conditions can also be described as the conditions that the polymer binder (B) satisfies with respect to the inorganic solid electrolyte (SE), the active material (AC), the conductive additive (CA) solid particles, and the dispersion medium (D). The following explains each condition.

[0018] Condition (1): The polymer binder (B) is dissolved in the dispersion medium (D). The polymer binder (B) contained in the electrode composition of the present invention exhibits the property of dissolving in the dispersion medium (D) (solubility). In the electrode composition, the polymer binder (B) usually exists dissolved in the dispersion medium (D), although this depends on the content of the dispersion medium (D). In an electrode composition containing the above components, when condition (1) is combined with conditions (2) to (4), the molecular chains (molecular structure) of the polymer (b) constituting the polymer binder (B) spread out in the dispersion medium (D), repelling adsorbed or nearby solid particles and effectively suppressing aggregation. Therefore, not only excellent initial dispersibility but also high dispersion stability of the electrode composition can be achieved. In the present invention, the solubility of the polymer binder (B) in the dispersion medium (D) can be appropriately imparted by the type of polymer (b) forming the polymer binder (B) (structure and composition of the polymer chain), the mass-average molecular weight of the polymer (b), the type or content of functional groups selected from the functional group group (a) described later, and the combination with the dispersion medium (D) (for example, the difference in SP values ​​described later).

[0019] In the present invention, "the polymer binder is dissolved in the dispersion medium" means that the polymer binder is dissolved in the dispersion medium in the electrode composition, for example, that the solubility in a solubility measurement is 10% by mass or more. Conversely, "the polymer binder is not dissolved in the dispersion medium (insoluble)" means that the solubility in a solubility measurement is less than 10% by mass. The method for measuring solubility is as follows: A specified amount of the polymer binder to be measured is weighed into a glass bottle, 100 g of the same type of dispersion medium as that contained in the electrode composition is added, and the mixture is stirred at a rotation speed of 80 rpm on a mix rotor at a temperature of 25°C for 24 hours. The transmittance of the resulting mixture after 24 hours of stirring is measured under the following conditions. This test (transmittance measurement) is performed by changing the amount of polymer binder dissolved (the specified amount above), and the upper limit concentration X (mass%) at which the transmittance is 99.8% is defined as the solubility of the polymer binder in the above dispersion medium. <Transmittance measurement conditions> Dynamic light scattering (DLS) measurement Equipment: DLS-8000 DLS measuring device manufactured by Otsuka Electronics Laser wavelength, power output: 488nm / 100mW Sample cell: NMR tube

[0020] Condition (2): Conductive additive in the dispersion medium (D) of polymer binder (B) Adsorption rate for (CA) [A CA ] is greater than 0% and less than or equal to 50% Being In an electrode composition containing the above components, combining condition (2) with other conditions suppresses excessive adsorption of the polymer binder (B) to the conductive additive (CA), improving the initial dispersibility and dispersion stability (collectively referred to as dispersion characteristics) of the conductive additive (CA), and enabling the sufficient construction of electron conduction paths. In terms of improving dispersion characteristics, the adsorption rate [A CA ] is preferably 2% or more, more preferably 5% or more, and even more preferably 10% or more. On the other hand, the adsorption rate [A CAThe upper limit is preferably 40% or less, more preferably less than 30%, and even more preferably 25% or less in terms of enabling both high-level dispersion characteristics and construction of an electron conduction path. In the present invention, the adsorption rate [A CA with respect to the conductive auxiliary agent (CA) can be appropriately set according to the type of the polymer (b) forming the polymer binder (B) (structure and composition of the polymer chain), the mass average molecular weight of the polymer (b), the type or content of the functional group selected from the functional group group (a) described later, the surface state of the conductive auxiliary agent (CA), etc.

[0021] The adsorption rate [A CA is a value measured using the conductive auxiliary agent (CA), the polymer binder (B), and the dispersion medium (D) contained in the electrode composition, and is an index indicating the degree of adsorption of the polymer binder (B) to the conductive auxiliary agent (CA) in the dispersion medium (D). Here, the adsorption of the polymer binder to the conductive auxiliary agent includes not only physical adsorption but also chemical adsorption (adsorption by formation of chemical bonds, adsorption by electron transfer, etc.). When the electrode composition contains a plurality of types of conductive auxiliary agents, the adsorption rate is defined as that for the conductive auxiliary agent having the same composition as the conductive auxiliary agent (type and content) in the electrode composition. Similarly, when the electrode composition contains a plurality of types of dispersion media, the adsorption rate is defined as that for the dispersion medium having the same composition as the dispersion medium (type and content) in the electrode composition. Also, when the electrode composition contains a plurality of types of polymer binders (B), the adsorption rate is defined as that for the plurality of types of polymer binders.

[0022] The adsorption rate [A CA (%) is a value measured as follows. Specifically, a 1% by mass binder solution is prepared by dissolving polymer binder (B) in dispersion medium (D). The polymer binder (B) and conductive additive (CA) are then mixed in a 15 mL vial at a mass ratio of 3:1. The mixture is stirred with a mix rotor at 80 rpm for 1 hour at room temperature (25°C), and then allowed to stand. The supernatant obtained by solid-liquid separation is filtered through a 1 μm pore size filter, and the entire filtrate is allowed to dry. The mass of polymer binder (B) remaining in the filtrate (the mass of polymer binder (B) that was not adsorbed by the conductive additive (CA)) W is then determined. PA Measure this mass W. PA The mass W of polymer binder (B) contained in the binder solution used for measurement. PB The adsorption rate of the polymer binder (B) to the conductive additive (CA) is calculated using the following formula. The average of the adsorption rates obtained by performing this operation twice is used as the adsorption rate [A]. CA Let it be ](%). Adsorption rate (%)=[(W PB -W PA ) / W PB ]×100

[0023] Condition (3): The average mass of polymer (b) constituting polymer binder (B) The average molecular weight must be 6,000 or more. In an electrode composition containing the above components, when condition (3) is combined with other conditions, the molecular chains (molecular structure) of polymer (b) spread out greatly in the dispersion medium (D), which more effectively suppresses the aggregation of solid particles and further enhances the dispersion characteristics. The mass-average molecular weight of the polymer is preferably 7,000 or more, more preferably 10,000 or more, even more preferably 50,000 or more, and particularly preferably 200,000 or more, in order to achieve further improvement in dispersion characteristics. On the other hand, the mass-average fraction can be 2,000,000 or less, and is preferably 1,000,000 or less, more preferably 700,000 or less, and even more preferably 600,000 or less, in order to suppress excessive coating of the solid particle surface and construct sufficient conduction paths. The mass-average molecular weight of polymer (b) can be appropriately adjusted by changing the type and content of polymerization initiators, polymerization time, polymerization temperature, etc.

[0024] - Measurement of molecular weight - In this invention, unless otherwise specified, the molecular weight of polymers and macromonomers refers to the mass-average molecular weight or number-average molecular weight on a standard polystyrene basis, determined by gel permeation chromatography (GPC). The basic measurement method involves setting the measurement conditions to either Measurement Condition 1 or Measurement Condition 2 (preferred) below. However, depending on the type of polymer or macromonomer, an appropriate eluent may be selected and used as appropriate. (Measurement condition 1) Column: Two TOSOH TSKgel Super AWM-H columns (product name, manufactured by Tosoh Corporation) are connected together. Carrier: 10 mM LiBr / N-methylpyrrolidone Measurement temperature: 40℃ Carrier flow rate: 1.0 ml / min Sample concentration: 0.1% by mass Detector: RI (refractive index) detector (Measurement condition 2) Column: A column consisting of TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, and TOSOH TSKgel Super HZ2000 (all product names, manufactured by Tosoh Corporation) is used. Carrier: Tetrahydrofuran Measurement temperature: 40℃ Carrier flow rate: 1.0 ml / min Sample concentration: 0.1% by mass Detector: RI (refractive index) detector

[0025] Condition (4): Conductive additive (CA) present in the active material layer formed by the electrode composition The average particle size must be less than 1.0 μm. The above condition (4) means that when an active material layer is formed with the electrode composition of the present invention, the average particle size of the conductive additive (CA) present in this active material layer is less than 1.0 μm. When condition (4) is combined with the other conditions in an electrode composition containing the above components, direct contact between solid particles in the active material layer is made possible, and electron conduction paths containing the conductive additive can be sufficiently constructed. The average particle size of the conductive additive (CA) in condition (4) shall be the value measured by the method described in <Evaluation 3: Average particle size of conductive additive in the active material layer> in the examples described later. Note that the conditions for forming the active material layer are not particularly limited and include the conditions described in "Formation of each layer (film deposition)" described later, for example, the conditions for fabricating each electrode sheet in the examples. The average particle size of the conductive additive (CA) is preferably 0.8 μm or less, more preferably 0.6 μm or less, and even more preferably 0.5 μm or less, in terms of further improvement of dispersion characteristics and construction of electronically conductive paths. The lower limit of the average particle size is not particularly limited, but for example, 0.05 μm is practical, and 0.1 μm or more is preferable. It should also be noted that the "average particle size of the conductive additive (CA)" in the electrode sheet for the all-solid-state secondary battery of the present invention, as described later, is also one preferred form. The average particle size of the conductive additive (CA) can be appropriately adjusted by changing the particle size, content, and surface condition of the conductive additive (CA) used, as well as the type of dispersion medium or polymer binder (e.g., adjusting the difference with the SP value) and the content of the polymer binder. For example, increasing the content of the conductive additive (CA) tends to increase the average particle size. Conversely, increasing the content of the polymer binder tends to decrease the average particle size.

[0026] Condition (4) above can be achieved by making the average particle size of the conductive additive (CA) in a dispersion prepared by mixing the polymer binder (B), dispersion medium (D), and conductive additive (CA) in the same type and mass ratio as the electrode composition less than 1.0 μm (condition (4A)), thereby improving the dispersion characteristics of the conductive additive (CA) in the electrode composition. The average particle size of the conductive additive (CA) under condition (4A) is the average particle size measured in a dispersion liquid prepared separately using the polymer binder (B), dispersion medium (D), and conductive additive (CA) contained in the electrode composition, in the same mass ratio (content) as in the electrode composition. By using this separately prepared dispersion liquid as the measurement target, the dispersibility of the polymer binder (B) with respect to the conductive additive (CA) in the dispersion medium (D) can be evaluated. The average particle size of the conductive additive (CA) in the above dispersion liquid is the value measured by the method described in the examples below. The preferred range for the average particle size under condition (4A) is the same as the range under condition (4).

[0027] The electrode composition of the present invention is preferably a slurry in which an inorganic solid electrolyte (SE), an active material (AC), and a conductive additive (CA) are dispersed in a dispersion medium (D), particularly a high-concentration slurry.

[0028] The solid content concentration of the electrode composition of the present invention is not particularly limited and can be set as appropriate. For example, at 25°C, it can be 20 to 80% by mass, preferably 30 to 75% by mass, and more preferably 40 to 70% by mass. The electrode of the present invention exhibits excellent dispersion characteristics, and therefore, the electrode composition can be a high-concentration composition (slurry) 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, and can also be, for example, 60% by mass or more. The upper limit is less than 100% by mass, and can be, for example, 90% by mass or less, preferably 85% by mass or less, and more preferably 80% by mass or less. In this 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 (D) described later. Furthermore, the content in total solid content refers to the content in 100% by mass of the total mass of solid content.

[0029] 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 refers to the amount of water contained in the electrode composition (mass ratio to the electrode composition), and specifically, it is the value measured by filtering through a 0.02 μm membrane filter and using Karl Fischer titration.

[0030] Because the electrode composition of the present invention exhibits the above-mentioned excellent properties, it can be preferably used as an electrode sheet for all-solid-state secondary batteries and as a material for forming the active material layer of all-solid-state secondary batteries. In particular, it can be preferably used as a material for forming the positive electrode active material layer and as a material for forming the negative electrode active material layer containing a negative electrode active material that expands and contracts significantly due to charging and discharging.

[0031] The following describes the components contained in and potentially contained in the electrode composition of the present invention.

[0032] <Inorganic solid electrolyte (SE)> The electrode composition of the present invention contains an inorganic solid electrolyte (SE). In this invention, an inorganic solid electrolyte refers to an inorganic solid electrolyte, and a solid electrolyte is a solid electrolyte that can move ions within itself. Since it does not contain organic materials 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 usually dissociate or become liberated into cations and anions. In this respect, they are clearly distinguished from inorganic electrolyte salts (LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), LiCl, etc.) that dissociate or become liberated into cations and anions in the electrolyte or polymer. 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, they do not have electronic conductivity.

[0033] The inorganic solid electrolyte contained in the electrode composition of the present invention can be appropriately selected from solid electrolyte materials 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, sulfide-based inorganic solid electrolytes are preferred. In the case of a lithium-ion battery in the all-solid-state secondary battery of the present invention, it is preferable that the inorganic solid electrolyte has ionic conductivity for lithium ions.

[0034] (i) Sulfide-based inorganic solid electrolyte The sulfide-based inorganic solid electrolyte is preferably one that contains sulfur atoms, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and is also an electronic insulator. The sulfide-based inorganic solid electrolyte is preferably one that contains at least Li, S, and P as elements and has lithium ion conductivity, but may contain other elements other than Li, S, and P as appropriate.

[0035] Examples of sulfide-based inorganic solid electrolytes include lithium-ion conductive inorganic solid electrolytes that satisfy the composition shown in the following formula (S1). L 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.

[0036] 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.

[0037] The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystalline (glass-ceramic), or partially crystalline. For example, a Li-PS glass containing Li, P, and S, or a Li-PS glass-ceramic containing Li, P, and S can be used. Sulfide-based inorganic solid electrolytes can be produced by the reaction of at least two raw materials from among lithium sulfide (Li2S), phosphorus sulfide (e.g., diphosphorus pentasulfide (P2S5)), 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., SiS2, SnS, GeS2).

[0038] In Li-PS-based glass and Li-PS-based glass ceramics, the ratio of Li2S to P2S5 is preferably 60:40 to 90:10, more preferably 68:32 to 78:22, in terms of the molar ratio of Li2S:P2S5. By setting the ratio of Li2S to P2S5 within this range, the lithium ion conductivity can be increased. Specifically, the lithium ion conductivity is preferably 1 × 10⁻⁶. -4 S / cm or more, more preferably 1 × 10 -3 It can be S / cm or more. There is no particular upper limit, but 1 × 10 -1 It is practical for the rate to be less than or equal to S / cm.

[0039] Examples of specific sulfide-based inorganic solid electrolytes include the following combinations of raw materials: For example, Li2S-P2S5, Li2S-P2S5-LiCl, Li2S-P2S5-H2S, Li2S-P2S5-H2S-LiCl, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2O5, Li2S-P2S5-SiS2, Li2S-P2S5-SiS2-LiCl, Li2S-P2S5-SnS, and Li2S-P2S5-Al2S3. , Li2S-GeS2, Li2S-GeS2-ZnS, Li2S-Ga2S3, Li2S-GeS2-Ga2S3, Li2S-GeS2-P2S5, Li2S-GeS2-Sb2S5, Li2S-GeS2-Al2S3, Li2S-SiS2, L i2S-Al2S3, Li2S-SiS2-Al2S3, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li 10 GeP2S 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 electrolyte materials 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.

[0040] (ii) Oxide-based inorganic solid electrolyte The oxide-based inorganic solid electrolyte is preferably one that contains oxygen atoms, has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and also has electronic insulating properties. Oxide-based inorganic solid electrolytes have an ionic conductivity of 1 × 10⁻⁶. -6 Preferably S / cm or more, 5 × 10 -6 It is more preferable that the S / cm is greater than 1 × 10 -5 It is particularly preferable that the S / cm or higher. There is no particular upper limit, but 1 × 10 -1It is practical that it is below S / cm.

[0041] Specific compound examples include, for example, Li xa La ya TiO3 [xa satisfies 0.3 ≤ xa ≤ 0.7, and ya satisfies 0.3 ≤ ya ≤ 0.7.](LLT); Li xb La yb Zr zb M bb 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 [[ID=**45**]]] (3-2xe) [[ID=**46**]]]M[[ID=**47**]]] ee [[ID=**48**]]] xe [[ID=**49**]]]D[[ID=**50**]]] ee [[ID=**51**]]]O(xe represents a number from 0 or more to 0.1 or less, and M [[ID=**52**]]] ee [[ID=**53**]]]represents a divalent metal atom. D [[ID=**54**]]] ee [[ID=**55**]]]represents a halogen atom or a combination of two or more halogen atoms.); Li [[ID=**56**]]] xf [[ID=**57**]]]Si[[ID=**58**]]] yf [[ID=**59**]]]O[[ID=**60**]]] zf [[ID=**61**]]](xf satisfies 1 ≤ xf ≤ 5, yf satisfies 0 < yf ≤ 3, and zf satisfies 1 ≤ zf ≤ 10.); Lixg S yg O zg (xg satisfies 1 ≤ xg ≤ 3, yg satisfies 0 < yg ≤ 2, and zg satisfies 1 ≤ zg ≤ 10); Li3BO3; Li3BO3-Li2SO4; Li2O-B2O3-P2O5; Li2O-SiO2; Li6BaLa2Ta2O 12 ; Li3PO (4-3 / 2w) N w (w is w < 1); Li having a LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4; La having a perovskite type crystal structure 0.55 Li 0.35 TiO3; LiTi2P3O having a NASICON (Natrium super ionic conductor) type crystal structure 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); Li7La3Zr2O having a garnet type crystal structure 12 (LLZ), etc. can be mentioned. Also, phosphorus compounds containing Li, P, and O are desirable. For example, lithium phosphate (Li3PO4); LiPON in which part of the oxygen element of lithium phosphate is substituted with a nitrogen element; LiPOD 1 (D 1 is preferably one or more elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au.) etc. can be mentioned. Furthermore, LiA 1 ON (A 1 is one or more elements selected from Si, B, Ge, Al, C, and Ga.) etc. can also be preferably used.

[0042] (iii) Halide-based inorganic solid electrolyte Halide-based inorganic solid electrolytes are preferably compounds that contain halogen atoms, possess conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, and have electronic insulating properties. The halogenated inorganic solid electrolyte is not particularly limited, but examples include LiCl, LiBr, LiI, and compounds such as Li3YBr6 and Li3YCl6 as described in ADVANCED MATERIALS, 2018, 30, 1803075. Among these, Li3YBr6 and Li3YCl6 are preferred.

[0043] (iv) Hydride-based inorganic solid electrolytes Hydride-based inorganic solid electrolytes are preferably compounds that contain hydrogen atoms, possess ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and have electronic insulating properties. The hydride-based inorganic solid electrolyte is not particularly limited, but examples include LiBH4, Li4(BH4)3I, and 3LiBH4-LiCl.

[0044] The inorganic solid electrolyte contained in the electrode composition of the present invention is preferably 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 size of the inorganic solid electrolyte (volume average particle size: D 50 The particle size 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. The upper limit is preferably 100 μm or less, more preferably 50 μm or less, and more preferably 10 μm or less. The particle size of inorganic solid electrolytes is measured using the following procedure: Dilute the inorganic solid electrolyte particles with water (or heptane if the substance is unstable in water) in a 20 mL sample bottle to prepare a 1% by mass dispersion. Irradiate the diluted dispersion sample with 1 kHz ultrasound for 10 minutes and use it for testing immediately thereafter. Using this dispersion sample, acquire data 50 times using a laser diffraction / scattering particle size distribution analyzer LA-920 (product name, manufactured by HORIBA) at a temperature of 25°C with a quartz cell to obtain the volume-average particle size. For other detailed conditions, refer to the Japanese Industrial Standard (JIS) Z 8828:2013 "Particle Size Analysis - Dynamic Light Scattering Method" as needed. Prepare five samples for each level and use their average value.

[0045] 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.

[0046] The electrode composition may contain one or more types of inorganic solid electrolytes. The content of the inorganic solid electrolyte in the electrode composition is not particularly limited and can be determined as appropriate. In terms of dispersion characteristics, the total amount of the active material and the inorganic solid electrolyte is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of solid content. As an upper limit, from the same viewpoint, it is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and particularly preferably 99% by mass or less.

[0047] <Active material (AC)> The electrode composition of the present invention contains an active material capable of inserting and releasing ions of a metal belonging to Group 1 or Group 2 of the periodic table. Examples of the active material (AC) include a positive electrode active material and a negative electrode active material.

[0048] (Positive electrode active material) The positive electrode active material is an active material capable of inserting and releasing ions of a metal belonging to Group 1 or Group 2 of the periodic table, and preferably one 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 obtained by decomposing the battery and using a transition metal oxide or an element that can be complexed with Li such as sulfur. Among them, it is preferable to use a transition metal oxide as the positive electrode active material, and the transition metal element M a (One or more elements selected from Co, Ni, Fe, Mn, Cu, and V) is more preferably a transition metal oxide having. Further, an element M b (Elements such as elements of Group 1 (Ia) of the metal periodic table other than lithium, elements of Group 2 (IIa) of the metal periodic table, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B) may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the amount (100 mol%) of the transition metal element M a . Those synthesized by mixing so that the molar ratio of Li / M a [[ID=1第十八条]] becomes 0.3 to 2.2 are more preferable. Specific examples of the transition metal oxide include a transition metal oxide having a (MA) layered rock salt type structure, a transition metal oxide having a (MB) spinel type structure, a (MC) lithium-containing transition metal phosphate compound, a (MD) lithium-containing transition metal halogenophosphate compound, and a (ME) lithium-containing transition metal silicate compound.

[0049] (MA) Specific examples of the transition metal oxide having a layered rock salt type structure include LiCoO2 (lithium cobaltate [LCO]), LiNi2O2 (lithium nickelate), LiNi 0.85 Co 0.10 Al 0.05 O2 (lithium nickel cobalt aluminum oxide [NCA]), LiNi 1 / 3 Co1 / 3 Mn 1 / 3 O2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn 0.5 O2 (lithium manganese nickelate) is one example. (MB)Specific examples of transition metal oxides having a spinel-type structure include LiMn2O4(LMO), LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8, and Li2NiMn3O8. Examples of (MC) lithium-containing transition metal phosphate compounds include olivine-type iron phosphates such as LiFePO4 and Li3Fe2(PO4)3, iron pyrophosphates such as LiFeP2O7, cobalt phosphates such as LiCoPO4, and monoclinic vanadium phosphates such as Li3V2(PO4)3 (lithium vanadium phosphate). Examples of (MD) lithium-containing transition metal halide phosphoric acid compounds include iron phosphate fluorides such as Li2FePO4F, manganese phosphate fluorides such as Li2MnPO4F, and cobalt phosphate fluorides such as Li2CoPO4F. Examples of (ME) lithium-containing transition metal silicate compounds include Li2FeSiO4, Li2MnSiO4, and Li2CoSiO4. In the present invention, transition metal oxides having a (MA) layered rock salt type structure are preferred, and LCO or NMC are more preferred.

[0050] The positive electrode active material contained in the electrode composition of the present invention is preferably in particulate form within the electrode composition. The shape of the particles is not particularly limited and may be flattened, amorphous, etc., but spherical or granular is preferred. When the positive electrode active material is in particulate form, the particle diameter (volume average particle diameter) of the positive electrode active material is not particularly limited, but for example, 0.1 to 50 μm is preferred, and 0.5 to 10 μm is more preferred. The particle diameter of the positive electrode active material particles can be prepared in the same manner as the particle diameter of the inorganic solid electrolyte, and the measurement method can also be the same as that for the particle diameter of the inorganic solid electrolyte.

[0051] The positive electrode active material obtained by the calcination method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0052] The electrode composition of the present invention may contain one or more positive electrode active materials. The content of the positive electrode active material in the electrode composition is not particularly limited and can be determined as appropriate. For example, based on 100% by mass of solids, 10 to 97% by mass is preferred, 30 to 95% by mass is more preferred, 40 to 93% by mass is even more preferred, and 50 to 90% by mass is particularly preferred.

[0053] (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.

[0054] 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 classified into hard carbonaceous materials (also called hard carbon) and graphite-based carbonaceous materials depending on the degree of graphitization. Furthermore, it is preferable that the carbonaceous materials have 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 have to be a single material; a mixture of natural graphite and artificial graphite as described in Japanese Patent Publication No. 5-90844, graphite with a coating layer as described in Japanese Patent Publication No. 6-4516, etc., can also be used. As the carbonaceous material, hard carbon or graphite is preferably used, and graphite is more preferably used.

[0055] 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 oxides of metal elements (metal oxides), composite oxides of metal elements or composite oxides of metal elements and metalloid elements (collectively referred to as metal composite oxides), and oxides of metalloid elements (metalloid oxides). Among these oxides, amorphous oxides are preferred, and chalcogenides, which are reaction products of metal elements and elements of Group 16 of the periodic table, are also preferred. In the present invention, metalloid elements refer to elements that exhibit properties intermediate between metal elements and nonmetalloid 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° in 2θ values ​​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° in 2θ values, and it is particularly preferable that there are no crystalline diffraction lines.

[0056] Among the group of compounds composed of the above amorphous oxides and chalcogenides, amorphous oxides of semimetal elements or the above chalcogenides are more preferable, and (composite) oxides composed of one kind alone or a combination of two or more kinds selected from the elements of Group 13 (IIIB) to Group 15 (VB) of the periodic table (for example, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi), or chalcogenides are particularly preferable. Specific examples of preferable amorphous oxides and chalcogenides include, for example, Ga2O3, GeO, PbO, PbO2, Pb2O3, Pb2O4, Pb3O4, Sb2O3, Sb2O4, Sb2O8Bi2O3, Sb2O8Si2O3, Sb2O5, Bi2O3, Bi2O4, GeS, PbS, PbS2, Sb2S3, or Sb2S5. As the negative electrode active material that can be used in combination with amorphous oxides centered on Sn, Si, and Ge, carbonaceous materials capable of occluding and / or releasing lithium ions or lithium metal, lithium alone, lithium alloys, and negative electrode active materials capable of alloying with lithium are preferably mentioned.

[0057] It is preferable from the viewpoint of high current density charge / discharge characteristics that oxides of metal or semimetal elements, particularly metal (composite) oxides and the above chalcogenides contain at least one of titanium and lithium as constituent components. Examples of metal composite oxides containing lithium (lithium composite metal oxides) include, for example, composite oxides of lithium oxide and the above metal (composite) oxides or the above chalcogenides, and more specifically, Li2SnO2. It is also preferable that the negative electrode active material, for example, a metal oxide contains a titanium element (titanium oxide). Specifically, Li4Ti5O 12 (lithium titanate [LTO]) is preferable in that it has excellent rapid charge / discharge characteristics because of the small volume change during the occlusion and release of lithium ions, the deterioration of the electrode is suppressed, and the life of the lithium ion secondary battery can be improved.

[0058] The lithium alloy as the negative electrode active material is not particularly limited as long as it is an alloy commonly used as the negative electrode active material of a secondary battery. For example, a lithium aluminum alloy, specifically, a lithium aluminum alloy having lithium as a base metal and adding 10% by mass of aluminum can be mentioned.

[0059] The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is commonly used as the negative electrode active material of a secondary battery. Such an active material has a large expansion and contraction due to charge and discharge of an all-solid-state secondary battery, and accelerates the deterioration of cycle characteristics. However, since the electrode composition of the present invention contains the above components and satisfies the above conditions, the deterioration of cycle characteristics can be suppressed. Examples of such an active material include an active material (alloy, etc.) having a silicon element or a tin element, and each metal such as Al and In. A negative electrode active material having a silicon element (silicon element-containing active material) that enables a higher battery capacity is preferable, and a silicon element-containing active material having a silicon element content of 50 mol% or more of all constituent elements is more preferable. Generally, a negative electrode containing these negative electrode active materials (for example, a Si negative electrode containing a silicon element-containing active material, a Sn negative electrode containing an active material having a tin element, etc.) can occlude more Li ions than a carbon negative electrode (graphite and acetylene black, etc.). That is, the amount of Li ions occluded per unit mass increases. Therefore, the battery capacity (energy density) can be increased. As a result, there is an advantage that the battery driving time can be lengthened. Examples of the silicon element-containing active material include silicon materials such as Si and SiOx (0 < x ≦ 1), and further, silicon-containing alloys containing titanium, vanadium, chromium, manganese, nickel, copper, lanthanum, etc. (for example, LaSi2, VSi2, La-Si, Gd-Si, Ni-Si), or organized active materials (for example, LaSi2 / Si). In addition, active materials containing a silicon element and a tin element such as SnSiO3 and SnSiS3 can be mentioned. Note that SiOx can be used as a negative electrode active material (semimetal oxide) itself, and can also be used as a negative electrode active material (its precursor material) capable of alloying with lithium because Si is generated by the operation of an all-solid-state secondary battery. Examples of negative electrode active materials containing tin include Sn, SnO, SnO2, SnS, SnS2, and active materials containing the above-mentioned silicon and tin elements. Furthermore, composite oxides with lithium oxide, such as Li2SnO2, can also be used.

[0060] 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.

[0061] The negative electrode active material contained in the electrode composition of the present invention is preferably in particulate form within the electrode composition. The shape of the particles is not particularly limited and may be flattened, amorphous, etc., but spherical or granular is preferred. When the negative electrode active material is in particulate form, the particle diameter (volume average particle diameter) of the negative electrode active material is not particularly limited, but for example, 0.1 to 60 μm is preferred, and 0.5 to 10 μm is more preferred. The particle diameter of the negative electrode active material particles can be prepared in the same manner as the particle diameter of the inorganic solid electrolyte, and the measurement method can also be the same as that for the particle diameter of the inorganic solid electrolyte.

[0062] The electrode composition of the present invention may contain one or more negative electrode active materials. The content of the negative electrode active material in the electrode composition is not particularly limited and can be determined as appropriate. For example, it is preferably 10 to 90% by mass, more preferably 20 to 85% by mass, even more preferably 30 to 80% by mass, and still more preferably 40 to 75% by mass, based on 100% by mass of solid content.

[0063] 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.

[0064] (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 more specifically, Li4Ti5O 12 Examples include Li2Ti2O5, LiTaO3, LiNbO3, LiAlO2, Li2ZrO3, Li2WO4, Li2TiO3, Li2B4O7, Li3PO4, Li2MoO4, Li3BO3, LiBO2, Li2CO3, Li2SiO3, SiO2, TiO2, ZrO2, Al2O3, B2O3, etc. Furthermore, the electrode surface containing the positive electrode active material or the negative electrode active material may be surface-treated with sulfur or phosphorus. Furthermore, the particle surfaces of the positive electrode active material or negative electrode active material may be surface-treated with active light or an active gas (such as plasma) before or after the above-mentioned surface coating.

[0065] <Conductive additive (CA)> The electrode composition of the present invention contains 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. It may also be a metal powder or metal fiber such as copper or nickel, or a conductive polymer such as polyaniline, polypyrrole, polythiophene, polyacetylene, or polyphenylene derivatives. In this invention, when an active material and a conductive additive are used in combination, the conductive additive is defined as one which does not function as an active material because, when the battery is charged and discharged, insertion and release of ions of metals belonging to Group 1 or Group 2 of the periodic table (preferably Li ions) does not occur. Therefore, among the conductive additives, those which can function as an active material 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 unique, but is determined by the combination with the active material.

[0066] The conductive additive contained in the electrode composition of the present invention is preferably in particulate form within the electrode composition. The shape of the particles is not particularly limited and may be flattened, amorphous, etc., but spherical or granular is preferred. 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, 0.02 μm or more and less than 1.0 μm is more preferred, and 0.03 to 0.5 μm is even more preferred. The particle size of the conductive additive can be adjusted in the same manner as the particle size of the inorganic solid electrolyte, and the measurement method can also be the same as that for the particle size of the inorganic solid electrolyte. The electrode composition of the present invention may contain one or more conductive additives. The content of the conductive additive in the electrode composition is not particularly limited and can be determined as appropriate. For example, it is preferably more than 0% by mass and 10% by mass or less, more preferably 1.0 to 5.0% by mass, and even more preferably 1.0 to 2.0% by mass, based on 100% by mass of solid content.

[0067] <Polymer Binder (B)> The electrode composition of the present invention contains one or more polymer binders (B). The polymer binders (B) are not particularly limited in their other properties, as long as they satisfy conditions (1) to (4), and can be set as appropriate. The preferred properties or physical characteristics of the polymer binder (B) and the polymer (b) constituting the polymer binder (B) will be described.

[0068] (Preferred physical properties or characteristics of polymer binder (B) and polymer (b)) The polymer binder (B) has an adsorption rate of 45% or less to the inorganic solid electrolyte (SE) in the dispersion medium (D) contained in the electrode composition [A SE It is preferable to show ]. In an electrode composition containing the above components and satisfying the above conditions, the polymer binder (B) further has the above adsorption rate [A SE When the conditions are met, the adsorption rate [A] is moderately adsorbed not only on the conductive additive (CA) but also on the inorganic solid electrolyte (SE), thereby increasing the dispersibility of the inorganic solid electrolyte (SE) and further improving the dispersion characteristics of the electrode composition, allowing for the construction of sufficient conduction paths. In terms of further improvement of the dispersion characteristics of the electrode composition and construction of conduction paths, the adsorption rate [A] SE The adsorption rate [A SE The lower limit of ] is practically 0% or more, preferably 5% or more, and more preferably 10% or more. In the present invention, the adsorption rate [A] for inorganic solid electrolytes (SE) SE The ] can be appropriately set depending on the type of polymer (b) that forms the polymer binder (B) (structure and composition of the polymer chain), the mass-average molecular weight of polymer (b), the type or content of functional groups selected from the functional group group (a) described later, the surface state of the inorganic solid electrolyte (SE), etc.

[0069] Adsorption rate [A SE ] is the adsorption rate of polymer binder (B) to inorganic solid electrolyte (SE) in dispersion medium (D), and is a value measured using inorganic solid electrolyte (SE), polymer binder (B), and dispersion medium (D) contained in the electrode composition. It is an index indicating the degree to which polymer binder (B) adsorbs to inorganic solid electrolyte (SE) in dispersion medium (D). Here, the adsorption of polymer binder (B) to inorganic solid electrolyte (SE) includes not only physical adsorption but also chemical adsorption (adsorption by chemical bond formation, adsorption by electron transfer, etc.). If the electrode composition contains multiple types of inorganic solid electrolytes, the adsorption rate shall be defined as the adsorption rate for inorganic solid electrolytes having the same composition (type and content) as the inorganic solid electrolytes in the electrode composition. Similarly, if the electrode composition contains multiple types of dispersion media, the adsorption rate shall be defined as the adsorption rate for dispersion media having the same composition (type and content) as the dispersion media in the electrode composition. Furthermore, if the electrode composition uses multiple types of polymer binders, the adsorption rate shall be defined as the adsorption rate for multiple types of polymer binders.

[0070] Adsorption rate [A SE The % (%) is measured using the inorganic solid electrolyte (SE), polymer binder (B), and dispersion medium (D) used in the preparation of the electrode composition, as follows. Specifically, a 1% by mass binder solution is prepared by dissolving polymer binder (B) in dispersion medium (D). The polymer binder (B) and inorganic solid electrolyte (SE) are then mixed in a 15 mL vial at a mass ratio of 42:1. The mixture is stirred with a mix rotor at 80 rpm for 1 hour at room temperature (25°C), and then allowed to stand. The supernatant obtained by solid-liquid separation is filtered through a 1 μm pore size filter, and the entire filtrate is allowed to dry. The mass of polymer binder (B) remaining in the filtrate (the mass of polymer binder (B) that was not adsorbed by the inorganic solid electrolyte (SE)) W is then determined. A Measure this mass W. A The mass W of polymer binder (B) contained in the binder solution used for measurement. B The adsorption rate of the polymer binder (B) to the inorganic solid electrolyte (SE) is calculated using the following formula. The average of the adsorption rates obtained by performing this operation twice is used as the adsorption rate [A]. SE Let it be ](%). Adsorption rate (%)=[(W B -W A ) / W B ]×100

[0071] Polymer (b) improves the affinity between the polymer binder (B) and the dispersion medium (D), and the dispersion characteristics of solid particles, for example, its SP value is 10-24 MPa. 1 / 2 Preferably, the pressure is 14-22 MPa. 1 / 2 It is more preferable that the pressure be 16-20 MPa. 1 / 2 It is even more preferable that this be the case. This section explains how to calculate the SP value. (1) Calculate the SP value of the constituent unit. First, for polymer (b), we determine the constituent units that determine the SP value. For example, when calculating the SP value of polymer (b), if the polymer is a chain polymer, the same constituent units derived from the raw material compound are used.

[0072] Next, unless otherwise specified, the SP value for each constituent unit is determined by the Hoy method (HLHoy JOURNAL OF PAINT TECHNOLOGY Vol.42, No.541, 1970, 76-118, and POLYMER HANDBOOK 4 th (See Chapter 59, VII, page 686, Tables 5 and 6, and the formulas in Table 6 below).

[0073]

number

[0074] (2) SP value of polymer (b) Using the constituent units determined as described above and the obtained SP values, the SP value of polymer (b) is calculated from the following formula. Note that the SP values ​​of the constituent units obtained in accordance with the above-mentioned literature are used as SP values ​​(unit: MPa). 1 / 2 ) converted to (for example, 1 cal 1 / 2 cm -3 / 2 ≈2.05J 1 / 2 cm -3 / 2 ≈2.05MPa 1 / 2 ) and use. SP p 2 =(sp1 2×W1)+(SP2 2 ×W2)+··· In the formula, SP1, SP2, etc., represent the SP values ​​of the constituent units, and W1, W2, etc., represent the mass fractions of the constituent units. In this invention, the mass fraction of a constituent unit is the mass fraction of the constituent component (the raw material compound that derives this constituent component) in the polymer that corresponds to the constituent unit. The SP value of polymer (b) can be adjusted depending on the type or composition of polymer (b) (types and content of constituent components), etc.

[0075] It is preferable for polymer (b) to have an SP value that satisfies the difference (absolute value) between the SP value of the dispersion medium (D) and the SP value within the range described later, in order to achieve even more advanced dispersion characteristics.

[0076] The moisture content of polymer (b) is preferably 100 ppm (by mass) or less. Furthermore, this polymer may be obtained by crystallizing and drying the polymer, or the polymer solution may be used as is.

[0077] Polymer (b) is preferably amorphous. In the present invention, "amorphous" typically means that no endothermic peaks due to crystal melting are observed when measured at the glass transition temperature. Polymer (b) may be a non-crosslinked polymer or a crosslinked polymer. Furthermore, if crosslinking of polymer (b) proceeds by heating or application of voltage, it is preferable that polymer (b) before crosslinking has a mass-average molecular weight within the range specified in condition (3) above, and it is also preferable that polymer (b) at the start of use of the all-solid-state secondary battery has a mass-average molecular weight within the range specified in condition (3) above.

[0078] It is preferable that polymer (b) and polymer binder (B) do not react with the inorganic solid electrolyte during the heating process in the preparation of the electrode composition, the fabrication of electrode sheets for all-solid-state secondary batteries, or the manufacturing of all-solid-state secondary batteries, as this suppresses the deterioration of dispersion characteristics, coating suitability, and consequently, battery specificity. Specifically, it is preferable that the polymer does not have an ethylenically double bond in its molecule. In the present invention, the statement that the polymer does not have an ethylenically double bond in its molecule includes embodiments in which the polymer has an ethylenically double bond within a range that does not impair the effects of the present invention, for example, when the amount present in the molecule (by nuclear magnetic resonance spectroscopy (NMR)) is 0.1% or less.

[0079] (polymer(b)) Polymer (b) is a polymer that satisfies condition (3) above and is capable of forming a polymer binder (B) that satisfies conditions (1), (2), and (4) above. Its type and composition, as well as the bonding mode (arrangement) of the constituent components that make up the main chain, are not particularly limited, and various polymers can be used as binder polymers for all-solid-state secondary batteries. As polymer (b), for example, polymers having a polymer chain of at least one bond selected from urethane bonds, urea bonds, amide bonds, imide bonds, and ester bonds, or a polymer chain of carbon-carbon double bonds as the main chain, are preferred. More specifically, polymers having urethane bonds, urea bonds, amide bonds, imide bonds, or ester bonds as the main chain include, for example, step polymerization (polycondensation, polyaddition, or addition condensation) polymers such as polyurethane, polyurea, polyamide, polyimide, and polyester. As polymers having a polymer chain of carbon-carbon double bonds as the main chain, for example, chain polymerization polymers such as fluoropolymers (fluorinated polymers), hydrocarbon polymers, vinyl polymers, and (meth)acrylic polymers are preferred. The bonding mode of the main chain in these polymers is not particularly limited and may be random bonding (random polymer), alternating bonding (alternating polymer), block bonding (block polymer), or graft bonding (graft polymer). Among these, chain polymers are preferred, hydrocarbon polymers, vinyl polymers, and (meth)acrylic polymers are more preferred, and (meth)acrylic polymers are even more preferred. Furthermore, the bonding mode of the main chain is preferably random bonding or block bonding. The polymer (b) constituting the polymer binder (B) may be one type or two or more types. When the polymer binder (B) is composed of two or more types of polymers (b), it is preferable that at least one of the polymers is a chain polymer, and it is more preferable that all of the polymers are chain polymers.

[0080] 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 mass-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 terminal groups at the ends of the polymer are not included in the main chain. Furthermore, the side chains of a polymer refer to molecular chains other than the main chain, and include short molecular chains and long molecular chains.

[0081] The constituent components that form polymer (b) are not particularly limited, but include components having a functional group (a) selected from the functional group group (a), components having substituents with 8 or more carbon atoms as side chains, macromonomer components, and other components. If the polymerization chain of a macromonomer component contains a component having a functional group (a) as a polymerization chain component, then this macromonomer component corresponds to a component having a functional group selected from the functional group group (a). The constituent components of polymer (b) are described below.

[0082] (Component having a functional group selected from functional group (a)) The polymer (b) preferably contains one or more components having a functional group (including bonds) selected from the following functional group group (a). When the polymer (b) contains a component having this functional group (hereinafter sometimes referred to as a functional group-containing component), the polymer binder (B) can exhibit suitable adsorption force to solid particles such as conductive additives (CA), thereby improving the dispersion characteristics of the electrode composition. This component may be any component that forms polymer (b). The functional group may be incorporated into the main chain of the polymer or into the side chain. When incorporated into the side chain, the functional group may be directly bonded to the main chain or bonded via a linking group. There are no particular restrictions on the linking group, but linking group L described later may be used. F These are some examples.

[0083] <Functional group group (a)> Hydroxyl group, amino group, carboxyl group, sulfo group, phosphate group, phosphonic acid group, sulfanyl group, ether bond (-O-), imino group (=NR, -NR-), ester bond (-CO-O-), amide bond (-CO-NR-), urethane bond (-NR-CO-O-), urea bond (-NR-CO-NR-), heterocyclic group, aryl group, carboxylic anhydride group

[0084] The amino group, sulfo group, phosphate group (phosphoryl group), phosphonic acid group, heterocyclic group, and aryl group included in functional group (a) are not particularly limited, but are synonymous with the corresponding group of substituent Z described later. However, the number of carbon atoms in the amino group is more preferably 0 to 12, even more preferably 0 to 6, and particularly preferably 0 to 2. When an amino group, ether bond, imino group (-NR-), ester bond, amide bond, urethane bond, urea bond, etc. are included in the ring structure, it is classified as a heterocyclic group. Hydroxy groups, amino groups, carboxyl groups, sulfo groups, phosphate groups, phosphonic acid groups, sulfanyl groups, etc. may form salts. Examples of salts include various metal salts, ammonium or amine salts, etc.

[0085] In chain polymers, components having ester bonds (excluding ester bonds that form carboxyl groups) or amide bonds mean components in which ester bonds or amide bonds are not directly bonded to atoms constituting the main chain of the chain polymer, or to atoms constituting the main chain of polymerization chains incorporated into the chain polymer as branched chains or pendant chains (for example, polymerization chains possessed by macromonomers), and do not include, for example, components derived from alkyl (meth)acrylates.

[0086] The chemical formulas enclosed in parentheses after each bond name, such as an ether bond, indicate the chemical structure of that bond. The terminal groups bonded to these groups are not particularly limited and can be selected from substituent Z described later, for example, alkyl groups. R in each bond represents a hydrogen atom or a substituent, with a hydrogen atom being preferred. The substituent is not particularly limited and can be selected from substituent Z described later, with alkyl groups being preferred. Note that ether bonds are included in carboxyl groups, hydroxyl groups, etc., but the -O- groups included in these are not considered ether bonds.

[0087] The carboxylic acid anhydride group is not particularly limited, but includes groups obtained by removing one or more hydrogen atoms from a dicarboxylic acid anhydride (for example, a group represented by formula (2a) below), and also the constituent components themselves obtained by copolymerizing polymerizable dicarboxylic acid anhydrides as copolymerizable compounds (for example, a constituent component represented by formula (2b) below). As for the group obtained by removing one or more hydrogen atoms from a dicarboxylic acid anhydride, a group obtained by removing one or more hydrogen atoms from a cyclic dicarboxylic acid anhydride is preferred. Examples of dicarboxylic acid anhydrides include acyclic dicarboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and benzoic anhydride, and cyclic dicarboxylic acid anhydrides such as maleic anhydride, phthalic anhydride, fumaric anhydride, succinic anhydride, and itaconic anhydride. The polymerizable dicarboxylic acid anhydride is not particularly limited, but includes dicarboxylic acid anhydrides having an unsaturated bond in the molecule, and is preferably a polymerizable cyclic dicarboxylic acid anhydride. Specifically, examples include maleic anhydride and itaconic anhydride. Although the carboxylic anhydride group derived from a cyclic dicarboxylic anhydride is also a heterocyclic group, in this invention it is classified as a carboxylic anhydride group. Examples of carboxylic acid anhydride groups include the group represented by formula (2a) or the component represented by formula (2b) below, but the present invention is not limited to these. In each formula, * indicates a bond position.

[0088] [ka]

[0089] A single functional group-containing component may have one or more functional groups, and if it has two or more, they may or may not be bonded to each other. In terms of adsorption to solid particles, particularly conductive additives (CA), and furthermore, dispersion properties, carboxyl groups, hydroxyl groups, or carboxylic anhydride groups are preferred as functional groups. When a functional group-containing component has two or more functional groups, the two or more functional groups included in functional group group (a) can be appropriately combined, but in terms of adsorption and dispersion properties, combinations of ether bonds and aryl groups, combinations of carboxyl groups and hydroxyl groups, combinations of carboxyl groups and carboxylic anhydride groups, and combinations of carboxyl groups, hydroxyl groups, or carboxylic anhydride groups are preferred.

[0090] Preferably, the above-mentioned functional group is incorporated into the side chain of polymer (b). In this case, examples of functional group-containing components include a component having the above-mentioned functional group directly or via a linking group in a substructure incorporated into the main chain, or a component having a polymer chain in which the above-mentioned functional group is incorporated as a substituent directly or via a linking group in a substructure incorporated into the main chain of polymer (b). The following describes the components having the above-mentioned functional groups directly or via linking groups in the substructures incorporated into the main chain, and components having polymer chains will be described later. In a functional component, the substructure incorporated into the main chain is not uniquely determined by the type of polymer (B), but is selected as appropriate. For example, in the case of a chain polymer, a carbon chain (carbon-carbon bond) can be used.

[0091] Linking group L that connects the substructure incorporated into the main chain to the above functional group F The 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), alkenylene groups (preferably with 2 to 6 carbon atoms, more preferably 2 to 3), arylene groups (preferably with 6 to 24 carbon atoms, more preferably 6 to 10), oxygen atoms, sulfur atoms, and imino groups (-NR). N -:R NThe group is formed by combining an alkylene group, 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 (-OP(OH)(O)-O-), a phosphonic acid linking group (-P(OH)(O)-O-), or a group relating to a combination thereof. Preferably, the linking group is 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 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, such as a -CO-O- group or a -CO-N(R N )-group(R N The above is true. A group containing ) is more preferably a -CO-O- group or a -CO-N(R N )-group(R N As described above, a group formed by combining () and an alkylene group is particularly preferred.

[0092] In the present invention, linking group L F The number of atoms constituting it is preferably 1 to 36, more preferably 1 to 24, even more preferably 1 to 12, and particularly preferably 1 to 6. Linking group L F The number of linked atoms 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 connecting a given structural part. For example, in the case of -C(=O)-O-, the linking group L F The number of atoms that make up the structure is 3, but the number of linked atoms is 2.

[0093] Substructures and linking groups L incorporated into the main chain F Each of these may have substituents other than the functional groups described above. Such substituents are not particularly limited and include, for example, groups selected from substituent Z described later, and groups other than the functional groups selected from functional group (a) are preferred.

[0094] The compounds that lead to the functional group-containing components (also called compounds having functional groups) are not particularly limited, but examples include compounds having at least one carbon-carbon unsaturated bond and at least one of the above functional groups. For example, compounds in which a carbon-carbon unsaturated bond and the above functional group are directly bonded, and compounds in which a carbon-carbon unsaturated bond and the above functional group are linked by a linking group L F This includes compounds linked via a carbon-carbon unsaturated bond, and further, compounds in which the functional group itself contains a carbon-carbon unsaturated bond (for example, the polymerizable cyclic dicarboxylic acid anhydride mentioned above). Furthermore, compounds having the above functional group include compounds in which the functional group can be introduced into polymer components after polymerization through various reactions (for example, alcohol, amino, mercapto, or epoxy compounds (including polymers) that can undergo addition or condensation reactions with components derived from carboxylic anhydrides, components having carbon-carbon unsaturated bonds, etc.). Moreover, compounds having the above functional group include compounds in which a carbon-carbon unsaturated bond and a macromonomer incorporating a functional group as a substituent in the polymerization chain are directly or linked to a linking group L. F This also includes compounds that are bonded via [a specific linkage / mechanism].

[0095] The functional group-containing components described above are not particularly limited as long as they have the functional group, but examples include (meth)acrylic compounds (M1) or other polymerizable compounds (M2) described later, components represented by any of the formulas (b-1) to (b-3) described later, and components obtained by introducing the functional group into the component represented by formula (1-1) described later. Specific examples of the functional group-containing components include, for example, the components in the exemplary polymers and polymers synthesized in the examples described later, but the present invention is not limited to these. The compounds having the above-mentioned functional group are not particularly limited, but examples include polymerizable cyclic dicarboxylic acid anhydrides and compounds obtained by introducing the above-mentioned functional group into (meth)acrylic acid short-chain alkyl ester compounds (short-chain alkyl means alkyl group with 3 or fewer carbon atoms). Examples of compounds obtained by introducing the above-mentioned functional group into polymerizable cyclic dicarboxylic acid anhydrides include dicarboxylic acid monoester compounds obtained by an addition reaction (ring-opening reaction) between a maleic anhydride compound and an alcohol, etc.

[0096] The total content of the above-mentioned functional group-containing component in polymer (b) is preferably 0.01 to 40% by mass, more preferably 0.02 to 30% by mass, even more preferably 0.05 to 20% by mass, particularly preferably 0.1 to 10% by mass, and also particularly preferably 0.2 to 8% by mass, in terms of the dispersion characteristics and adsorption properties of the polymer binder (B). If polymer (b) has multiple functional group-containing components, the total content of functional group-containing components shall be the sum of the content of each component. Furthermore, even if a single component has multiple or multiple types of functional groups, the content of functional group-containing components usually refers to the content of that component. In addition, the total content of functional group-containing components also includes the content of components (macromonomer components) that have polymerization chains incorporating the above-mentioned functional groups as substituents, as described later. When polymer (b) has multiple functional group-containing components (including macromonomer components), the content of the functional group-containing components described below is appropriately determined considering the total content. For example, when polymer (b) has two types of functional group-containing components, the content of one functional group-containing component is preferably, for example, 0.005 to 30% by mass, more preferably 0.01 to 20% by mass, even more preferably 0.05 to 8% by mass, and particularly preferably 0.1 to 3% by mass. The content of the other functional group-containing component is preferably, for example, 0.005 to 10% by mass, more preferably 0.01 to 10% by mass, and even more preferably 0.05 to 2% by mass. Furthermore, the mass ratio of the content of one functional group-containing component to the content of the other functional group-containing component [content of one functional group-containing component / content of the other functional group-containing component] is preferably, for example, 0.001 to 5000, more preferably 0.01 to 1000, and even more preferably 0.02 to 200. When polymer (b) contains a functional group component having a carboxyl group and a functional group component having a carboxylic acid anhydride, the respective contents of the functional group component having a carboxyl group and the functional group component having a carboxylic acid anhydride in the polymer are appropriately determined considering the total contents. For example, in one preferred embodiment, the respective contents can be within the same range as when polymer (b) has two types of functional group components. However, the content of the functional group component having a carboxyl group may be the content of one of the functional group components or the content of the other functional group component.

[0097] (Components having substituents with 8 or more carbon atoms as side chains) The polymer (b) preferably contains one or more components having substituents with 8 or more carbon atoms as side chains. When polymer (b) contains these components, the polarity (SP value) of polymer (b) decreases, which can increase the solubility of the polymer binder (B) in the dispersion medium (D), leading to improved dispersion properties. This component may be any of the components forming polymer (b), and its substituent having 8 or more carbon atoms is introduced into the side chain of polymer (b) or as part thereof. This component has substituents having 8 or more carbon atoms directly or via linking groups in the substructure incorporated into the main chain of polymer (b).

[0098] The substructures incorporated into the main chain of polymer (b) are appropriately selected depending on the type of polymer, etc., as described above. Substituents having 8 or more carbon atoms are not particularly limited, and examples include the substituent Z described later, which has 8 or more carbon atoms. When a component includes a polymerization chain as a side chain, substituents having 8 or more carbon atoms include substituents having 8 or more carbon atoms on each component constituting this polymerization chain, but the polymerization chain as a whole is not considered a substituent with 8 or more carbon atoms. Examples of substituents having 8 or more carbon atoms include long-chain alkyl groups having 8 or more carbon atoms, cycloalkyl groups having 8 or more carbon atoms, aryl groups having 8 or more carbon atoms, aralkyl groups having 8 or more carbon atoms, and heterocyclic groups having 8 or more carbon atoms, with long-chain alkyl groups having 8 or more carbon atoms being preferred. The number of carbon atoms in this substituent may be 8 or more, preferably 10 or more, and more preferably 12 or more. There is no particular upper limit, but it is preferably 24 or less, more preferably 20 or less, and even more preferably 16 or less. The number of carbon atoms in the substituent indicates the number of carbon atoms constituting this substituent, and if this substituent has further substituents, the number of carbon atoms constituting those further substituents is also included.

[0099] The linking group that connects the substructure incorporated into the main chain with substituents having 8 or more carbon atoms is not particularly limited, and is the linking group L in the functional group-containing component described above. F The same as above, but particularly preferred are the -CO-O- group or -CO-N(R N )-group(R N As stated above.

[0100] The substructures, linking groups, and substituents having 8 or more carbon atoms incorporated into the main chain may each have substituents. Such substituents are not particularly limited and include, for example, groups selected from substituent Z described later, and groups other than functional groups selected from functional group (a) are preferred.

[0101] The constituent component having a substituent with 8 or more carbon atoms can be constructed by appropriately combining the substructure incorporated into the main chain, the substituent with 8 or more carbon atoms, and the linking group. For example, it is preferable that the constituent component is represented by the following formula (1-1). [ka]

[0102] In formula (1-1), R 1R represents a hydrogen atom or an alkyl group (the number of carbon atoms is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 3). 1 The alkyl group that can be selected may have substituents. The substituent is not particularly limited, but examples include substituent Z as described above, and groups other than the functional group selected from functional group (a) are preferred, for example, halogen atoms are preferred.

[0103] R 2 This indicates a group having a substituent with 8 or more carbon atoms. In the present invention, a group having a substituent is a group consisting of the substituent itself (where the substituent is R 1 It bonds directly to the carbon atom in the above formula. ) and R 2 A group consisting of a linking group that connects the carbon atom and substituent in the above formula to which the carbon atom is bonded, and a substituent (where the substituent is R 1 It is bonded to the carbon atom in the above formula via a linking group. ) and are included. R 2 substituents having 8 or more carbon atoms, and R 2 The linking groups that may be present are as described above. 2 As such, -C(=O)-O-long-chain alkyl groups with 8 or more carbon atoms are particularly preferred. In the above equation (1-1), R 1 The carbon atom adjacent to the carbon atom to which the substituent is bonded has two hydrogen atoms, but in the present invention, it may have one or two substituents. The substituent is not particularly limited, but examples include substituent Z described later, and a group other than the functional group selected from functional group (a) is preferred.

[0104] The constituent components having substituents with 8 or more carbon atoms are preferably, for example, constituent components derived from compounds having substituents with 8 or more carbon atoms among the (meth)acrylic compounds (M1) described later, and constituent components derived from compounds having substituents with 8 or more carbon atoms among the other polymerizable compounds (M2) described later, with long-chain alkyl ester compounds of (meth)acrylic acid (having 8 or more carbon atoms) being preferred. Specific examples of constituent components having substituents with 8 or more carbon atoms include the constituent components of the exemplary polymers and polymers synthesized in the examples described later, but the present invention is not limited to these.

[0105] The content of the constituent component having a substituent with 8 or more carbon atoms in polymer (b) is not particularly limited, but is preferably 20 to 99.9% by mass, more preferably 30 to 99.5% by mass, even more preferably 40 to 99% by mass, particularly preferably 60 to 98% by mass, and most preferably 80 to 95% by mass, in terms of the dispersion characteristics of binder (B).

[0106] (Other components) Polymer (b) may contain components other than the functional group-containing components and components other than those having substituents with 8 or more carbon atoms (referred to as "other components"). Other components are not particularly limited as long as they can constitute polymer (b), and can be appropriately selected depending on the type of polymer (b). For example, components derived from compounds among the (meth)acrylic compounds (M1) and other polymerizable compounds (M2) described later that do not have the functional group and substituents with 8 or more carbon atoms can be cited. Other preferred components include those having substituents with 7 or fewer carbon atoms. These components are the same as the components having substituents with 8 or more carbon atoms mentioned above, except that they have substituents with 7 or fewer carbon atoms instead of substituents with 8 or more carbon atoms. Specifically, components derived from alkyl ester compounds of (meth)acrylic acid having 7 or fewer carbon atoms are preferred, and examples include components derived from methyl (meth)acrylate and ethyl (meth)acrylate. The content of other components in polymer (b) is not particularly limited and is appropriately determined from the range of 0 to 100% by mass, taking into consideration the content of the above-mentioned components. If polymer (b) contains other components, for example, it is preferably 1 to 60% by mass, more preferably 2 to 40% by mass, and even more preferably 5 to 20% by mass.

[0107] (Macromonomer components) It is preferable that polymer (b) has a main chain composed of at least one of the above-mentioned components, and further, it is also preferable that polymer (b) contains macromonomer components in its main chain (i.e., polymer (b) corresponds to a graft polymer). That is, each of the above-mentioned components may be incorporated as a main chain component constituting the main chain of polymer (b), or as a polymerization chain component constituting the side chain of polymer (b), for example, the polymerization chain. When each component is incorporated as a polymer chain component constituting a side chain of polymer (b), for example, a polymerization chain, the main chain components constituting the main chain of polymer (b) can be components derived from macromonomers having polymerization chains (also called macromonomer components). Examples of macromonomers that lead to macromonomer components include those that have polymerization chains directly or via linking groups in the substructure incorporated into the main chain of polymer (b). The substructure incorporated into the main chain of polymer (b) is appropriately selected according to the type of polymer, etc., as described above. The linking group is not particularly limited, and is the linking group L in the functional group-containing component described above. FThe linking group is the same as above, but preferably includes a linking group containing a structural part (residue) derived from a chain transfer agent, polymerization initiator, etc., used in the synthesis of the polymer chain, and further preferably includes a linking group in which this structural part (residue) is bonded to a structural part derived from a (meth)acrylic compound (M1) that reacts with the chain transfer agent, for example, a structural part (glycidyl group) derived from a glycidyl (meth)acrylic acid ester compound. The chain transfer agent is not particularly limited, but examples include 3-mercaptopropionic acid, mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptoisobutyric acid, 2-mercaptoethanol, 6-mercapto-1-hexanol, 2-aminoethanethiol, 2-aminoethanethiol hydrochloride, etc. Examples of linking groups consisting of a structural part derived from a chain transfer agent and a structural part derived from a (meth)acrylic compound (M1) include a -CO-O-alkylene group and a -X-CO-(X)n-alkylene-S- group. Here, X represents an oxygen atom or -NH-, and n is 0 or 1. More specifically, the linking groups in the constituent component (X) of the polymer synthesized in the examples are mentioned. The number of atoms constituting the linking group in the macromonomer is preferably 1 to 36, more preferably 1 to 30, and even more preferably 1 to 24. The number of linked atoms in the linking group is preferably 16 or less, more preferably 12 or less, and even more preferably 10 or less.

[0108] The polymerization chain of a macromonomer is not particularly limited and includes polymerization chains having functional group-containing components, components having substituents with 8 or more carbon atoms, and other components as polymerization chain components. Specifically, this includes polymerization chains of chain polymers described later. When a polymerization chain contains the above-mentioned functional group-containing components as its polymerization chain components, this macromonomer component corresponds to the above-mentioned functional group-containing component (the "component having a polymerization chain") that constitutes polymer (b), regardless of the presence or absence of components having substituents with 8 or more carbon atoms and other components. However, even if a macromonomer component has a linking group having a functional group selected from the above-mentioned functional group group (a), it is considered a "macromonomer component" as long as the polymerization chain does not contain the above-mentioned functional group-containing component. The content of functional group-containing components, components having substituents with 8 or more carbon atoms, and other components in the polymerization chain is not particularly limited, but it is preferable that the content of each component in polymer (b) is within the range that satisfies the content of each component in polymer (b) as described above when converted to the content in polymer (b). To give an example of the content of each component, for example, the content of functional group-containing components incorporated into the macromonomer is preferably 1 to 100% by mass, more preferably 3 to 80% by mass, even more preferably 5 to 70% by mass, and particularly preferably 5 to 25% by mass. The content of components having substituents with 8 or more carbon atoms is preferably 0 to 90% by mass, more preferably 1 to 70% by mass, even more preferably 5 to 50% by mass in one embodiment, and more preferably 70 to 90% by mass in another embodiment. The content of other components is preferably 0 to 50% by mass, more preferably 0 to 30% by mass, and even more preferably 0 to 20% by mass.

[0109] The number-average molecular weight of the macromonomer is not particularly limited, but is preferably 500 to 100,000, more preferably 1,000 to 50,000, and even more preferably 2,000 to 20,000, in that it can further strengthen the binding force of the solid particles and their adhesion to the current collector while maintaining excellent dispersion properties. The content of macromonomer components in polymer (b) is set to a range that satisfies the respective content requirements when the macromonomer components are included in the content of each of the above-mentioned components. The content of macromonomer components alone in polymer (b) is preferably 0.1 to 70% by mass, more preferably 2 to 70% by mass, even more preferably 5 to 60% by mass, particularly preferably 8 to 50% by mass, and most preferably 10 to 40% by mass, in terms of the dispersion characteristics and adsorption properties of the polymer binder (B).

[0110] The following describes in detail chain polymerization polymers suitable for the present invention. (Hydrogen polymers) Examples of hydrocarbon polymers include polyethylene, polypropylene, natural rubber, polybutadiene, polyisoprene, polystyrene, polystyrene-butadiene copolymer, styrene-based thermoplastic elastomer, polybutylene, acrylonitrile-butadiene copolymer, or hydrogenated polymers thereof. Examples of styrene-based thermoplastic elastomers or their hydrogenated products are not particularly limited, but include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated SIS, styrene-butadiene-styrene block copolymer (SBS), hydrogenated SBS, styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), and random copolymers corresponding to the above block copolymers such as SEBS. In the present invention, hydrocarbon polymers that do not have unsaturated groups (e.g., 1,2-butadiene components) bonded to the main chain are preferred in that they can suppress the formation of chemical crosslinks. The above-mentioned hydrocarbon polymer preferably contains the functional group-containing components described above, and preferably contains components derived from polymerizable cyclic dicarboxylic acid anhydrides such as maleic anhydride. Furthermore, it is preferable to include the above-mentioned components having substituents with 8 or more carbon atoms. The content of constituent components in the hydrocarbon polymer is not particularly limited and can be appropriately selected considering conditions (1) to (4), as well as other physical properties, etc., and can be set to the range described above, for example.

[0111] (Vinyl polymer) Examples of vinyl polymers include polymers containing, for example, 50 mol% or more of vinyl monomers other than (meth)acrylic compounds (M1). Examples of vinyl monomers include vinyl compounds described later. Specifically, examples of vinyl polymers include polyvinyl alcohol, polyvinyl acetal, polyvinyl acetate, or copolymers containing these. This vinyl polymer preferably contains the above-mentioned functional group-containing components in addition to the components derived from vinyl monomers, and more preferably contains the above-mentioned components having substituents with 8 or more carbon atoms. The content of constituent components in a vinyl polymer is not particularly limited and is appropriately selected considering conditions (1) to (4), as well as other physical properties. For example, it is preferable that the content of constituent components derived from vinyl monomers in the total constituent components of a vinyl polymer is the same as the content of constituent components derived from (meth)acrylic compound (M1) in a (meth)acrylic polymer. Here, if constituent components having substituents with 8 or more carbon atoms and constituent components having functional groups are constituent components derived from vinyl monomers, the content of these constituent components is included in the content of constituent components derived from vinyl monomers. The content of constituent components having substituents with 8 or more carbon atoms and the content of constituent components having functional groups in the total constituent components of a vinyl polymer are as described above. The content of constituent components derived from (meth)acrylic compound (M1) is not particularly limited as long as it is less than 50 mol%, but it is preferably 0 to 30 mol%.

[0112] ((meth)acrylic polymer) As the (meth)acrylic polymer, a polymer obtained by copolymerizing at least one (meth)acrylic compound (M1) selected from (meth)acrylic acid compounds, (meth)acrylic acid ester compounds, (meth)acrylamide compounds, and (meth)acrylnitrile compounds is preferred. A polymer having at least one of the components derived from this (meth)acrylic compound (M1) and components having substituents with 8 or more carbon atoms and components having functional groups is preferred. A polymer containing components derived from other polymerizable compounds (M2) is also preferred.

[0113] Examples of (meth)acrylic acid ester compounds include alkyl (meth)acrylic acid ester compounds, aryl (meth)acrylic acid ester compounds, heterocyclic (meth)acrylic acid ester compounds, and polymer chain (meth)acrylic acid ester compounds, with alkyl (meth)acrylic acid ester compounds being preferred. The number of carbon atoms in the alkyl group constituting the alkyl (meth)acrylic acid ester compound is not particularly limited, but can be, for example, 1 to 24, preferably 3 to 20, more preferably 4 to 16, and even more preferably 8 to 14, in terms of dispersibility and adhesion. 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, preferably 6 to 10, and preferably 6. In the (meth)acrylamide compound, the nitrogen atom of the amide group may be substituted with an alkyl group or an aryl group. Other polymerizable compounds (M2) are not particularly limited and include vinyl compounds such as styrene compounds, vinylnaphthalene compounds, vinylcarbazole compounds, allyl compounds, vinyl ether compounds, vinyl ester compounds, dialkyl itaconates, and unsaturated carboxylic acid anhydrides, as well as fluorinated products thereof. Examples of vinyl compounds include the "vinyl monomers" described in Japanese Patent Application Publication No. 2015-88486. The (meth)acrylic compound (M1) and other polymerizable compounds (M2) may have substituents. The substituents are not particularly limited, and preferably include groups selected from substituent Z described later.

[0114] The content of constituent components in the (meth)acrylic polymer is not particularly limited and is appropriately selected considering conditions (1) to (4), as well as other physical properties. For example, the content of constituent components derived from the (meth)acrylic compound (M1) in the total constituent components of the (meth)acrylic polymer is not particularly limited and is appropriately set in the range of 0 to 100 mol%. The upper limit can be, for example, 90 mol%. Here, if constituent components having substituents with 8 or more carbon atoms and functional group-containing constituent components are constituent components derived from the (meth)acrylic compound (M1), the content of these constituent components is included in the content of constituent components derived from the (meth)acrylic compound (M1). The content of the constituent components having substituents with 8 or more carbon atoms, the functional group constituent components, and the other constituent components in the total constituent components of the (meth)acrylic polymer are as described above. The content of other polymerizable compounds (M2) in the total constituent components of the (meth)acrylic polymer is not particularly limited, but can be, for example, 50 mol% or less, preferably 1 to 30 mol%, more preferably 1 to 20 mol%, and even more preferably 2.5 to 20 mol%.

[0115] The (meth)acrylic compound (M1) and other polymerizable compounds (M2) that lead to the constituent components of (meth)acrylic polymers and vinyl polymers are preferably compounds represented by the following formula (b-1). These compounds are preferably compounds that lead to constituent components having 8 or more carbon atoms, or compounds that are different from the compounds that lead to the functional group-containing constituent components mentioned above.

[0116] [ka]

[0117] In the formula, R 1represents a hydrogen atom, a hydroxyl group, a cyano group, a halogen atom, an alkyl group (preferably with 1 to 24 carbon atoms, more preferably with 1 to 12 carbon atoms, and particularly preferably with 1 to 6 carbon atoms), an alkenyl group (preferably with 2 to 24 carbon atoms, more preferably with 2 to 12 carbon atoms, and particularly preferably with 2 to 6 carbon atoms), an alkynyl group (preferably with 2 to 24 carbon atoms, more preferably with 2 to 12 carbon atoms, and particularly preferably with 2 to 6 carbon atoms), or an aryl group (preferably with 6 to 22 carbon atoms, and more preferably with 6 to 14 carbon atoms). Among these, a hydrogen atom or an alkyl group is preferred, and a hydrogen atom or a methyl group is more preferred.

[0118] R 2 R represents a hydrogen atom or substituent. 2 The substituents that can be chosen are not particularly limited, but include alkyl groups (branched chains are also acceptable, but straight chains are preferred), alkenyl groups (2 to 12 carbon atoms are preferred, 2 to 6 carbon atoms are more preferred, and 2 or 3 carbon atoms are particularly preferred), aryl groups (6 to 22 carbon atoms are preferred, and 6 to 14 carbon atoms are more preferred), aralkyl groups (7 to 23 carbon atoms are preferred, and 7 to 15 carbon atoms are more preferred), and cyano groups. The number of carbon atoms in the alkyl group is the same as the number of carbon atoms in the alkyl group constituting the (meth)acrylate alkyl ester compound described above, but long-chain alkyl esters with 8 or more carbon atoms, or alkyl esters with 7 or fewer carbon atoms are preferred.

[0119] L 1 This is a linking group, and is not particularly limited, but examples include a linking group in the component having a substituent with 8 or more carbon atoms as described above. The above linking group may have any substituent. The number of atoms constituting the linking group and the number of linked atoms are as described above. Examples of arbitrary substituents include substituent Z, which will be described later, such as alkyl groups or halogen atoms.

[0120] n is 0 or 1, and 1 is preferred. However, -(L 1 ) n -R 2 If n represents one type of substituent (e.g., an alkyl group), then set n to 0, and R 2 Let this be a substituent (alkyl group). In the above formula (b-1), the carbon atom that forms the polymerizable group is R 1 Carbon atoms that are not bonded are represented as unsubstituted carbon atoms (H2C=), but they may have substituents. There are no particular restrictions on substituents, but for example, R 1 The above groups can be considered as such. Furthermore, groups that may have substituents, such as alkyl groups, aryl groups, alkylene groups, and arylene groups, may have substituents to the extent that they do not impair the effects of the present invention. The substituents are not particularly limited and include, for example, groups selected from substituent Z described later, specifically halogen atoms, etc.

[0121] As the (meth)acrylic compound (M1) mentioned above, compounds represented by the following formulas (b-2) or (b-3) are also preferred. This compound is preferably different from a compound that derives a component having a substituent with 8 or more carbon atoms, or a compound that derives a component having the above-mentioned functional group.

[0122] [ka]

[0123] R 1 , n is equivalent to the above equation (b-1). R 3 R 2 It is synonymous with [the above]. L 2 is a linking group, and the above L 1 The description can be preferably applied. L 3 is a linking group, and the above L 1 The description can be preferably applied, and an alkylene group having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms) is preferred. m is an integer between 1 and 200, preferably between 1 and 100, and more preferably between 1 and 50.

[0124] In the above formulas (b-1) to (b-3), the carbon atom that forms the polymerizable group is R 1Carbon atoms that are not bonded are represented as unsubstituted carbon atoms (H2C=), but they may have substituents. There are no particular restrictions on substituents, but for example, R 1 The above groups can be considered as such. Furthermore, in formulas (b-1) to (b-3), groups that may take substituents, such as alkyl groups, aryl groups, alkylene groups, and arylene groups, may have substituents to the extent that they do not impair the effects of the present invention. The substituents may be any substituents other than the functional groups selected from the functional group group (a), for example, groups selected from substituent Z described later, specifically halogen atoms, etc.

[0125] As described above, polymer (b) is preferably a random polymer or a block polymer. If polymer (b) is a block polymer, the number of blocks (segments) forming the block polymer is not particularly limited as long as it is 2 or more, and can be 2 to 5, with 2 or 3 being preferred. Examples of block polymers include AB type (a polymer in which one block A and one block B are bonded together to form one polymer chain (main chain)), ABA type (a polymer in which two block As are bonded to both ends of one block B to form one polymer chain (main chain)), and ABC type (a polymer in which one block A, one block B, and one block C are bonded in this order to form one polymer chain (main chain)). Among these, the ABA type is preferred. Here, blocks A, B, and C may each consist of one type of component, or they may each consist of two or more types of components. When there are two or more types of components, the combination (arrangement) of each component is not particularly limited and may be random, alternating, block, etc., but random is preferred.

[0126] In polymer (b), the components constituting block A are not particularly limited, but preferably include the other components mentioned above, and more preferably include components derived from alkyl ester compounds of (meth)acrylic acid having 7 or fewer carbon atoms. The components constituting block B are not particularly limited, but preferably include the functional group-containing components and components having substituents with 8 or more carbon atoms mentioned above. Polymer (b) having such blocks can have improved dispersion properties. The content of each block in the block polymer is not particularly limited and is set appropriately considering conditions (1) to (4), as well as other physical properties. For example, the content of block A containing the above components in polymer (b) is preferably 5 to 60% by mass, more preferably 8 to 50% by mass, and even more preferably 10 to 40% by mass. The content of block B containing the above functional group-containing components and components having substituents with 8 or more carbon atoms in polymer (b) is preferably 40 to 95% by mass, more preferably 50 to 92% by mass, and even more preferably 60 to 90% by mass. The content of each component in the block polymer is not particularly limited, and is set according to the type of polymer (b) and the total content of all components of polymer (b).

[0127] The terminal groups of polymer (b) are modified according to the polymerization method, polymerization termination method, etc., by introducing appropriate groups such as hydrogen atoms, chain transfer agent residues, initiator residues, etc.

[0128] The chain polymer (each component and raw material compound) may have substituents. The substituents are not particularly limited, and preferably include groups selected from substituent Z below, and groups other than the functional groups included in the above-mentioned functional group group (a) are preferred.

[0129] - Substituent Z - Alkyl groups (preferably C1-C20 alkyl groups, e.g., methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl groups (preferably C2-C20 alkenyl groups, e.g., vinyl, allyl, oleyl, etc.), alkynyl groups (preferably C2-C20 alkynyl groups, e.g., ethynyl, butadiinyl, phenylethynyl, etc.), cycloalkyl groups (preferably C3-C20 cycloalkyl groups, e.g., cyclopropyl, cyclopentyl) , cyclohexyl, 4-methylcyclohexyl, etc. In this invention, when we refer to alkyl groups, it usually means including cycloalkyl groups, but here it is described separately.), aryl groups (preferably aryl groups having 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl groups (preferably aralkyl groups having 7 to 23 carbon atoms, for example, benzyl, phenethyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, more preferably at least one oxygen atom, a sulfur atom, a nitrogen atom) It is a heterocyclic group having a 5 or 6 membered ring. 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) (Xy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy groups (groups in which an -O- group is bonded to the above heterocyclic group), alkoxycarbonyl groups (preferably alkoxycarbonyl groups having 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, etc.), aryloxycarbonyl groups (preferably aryloxycarbonyl groups having 6 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(-NH2), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl groups (preferably sulfamoyl groups having 0 to 20 carbon atoms, for example, N,N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyl groups (alkylcarbonyl groups, alkenylcarbonyl groups, alkynylcarbonyl groups, arylcarbonyl groups) The acyl group includes a heterocyclic carbonyl group, preferably a carbon 1 to 20 acyl group, for example, acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotinoyl, etc., and the acyloxy group includes alkylcarbonyloxy groups, alkenylcarbonyloxy groups, alkynylcarbonyloxy groups, and heterocyclic carbonyloxy groups, preferably a carbon 1 to 20 acyloxy group, for example, acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyl (e.g., noyloxy, acryloyloxy, methacryloyloxy, crotonoyloxy, nicotinoyloxy), allyloxy group (preferably allyloxy group having 7 to 23 carbon atoms, e.g., benzoyloxy, naphthoyloxy), carbamoyl group (preferably carbamoyl group having 1 to 20 carbon atoms, e.g., N,N-dimethylcarbamoyl, N-phenylcarbamoyl), acylamino group (preferably acylamino group having 1 to 20 carbon atoms, e.g., acetylamino, benzoylamino), alkylthio group (preferably alkylthio group having 1 to 20 carbon atoms) O groups (e.g., methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio groups (preferably arylthio groups having 6 to 26 carbon atoms, for example, phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), heterocyclic thio groups (groups in which an -S- group is bonded to the above heterocyclic group), alkylsulfonyl groups (preferably alkylsulfonyl groups having 1 to 20 carbon atoms, for example, methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl groups (preferably arylsulfonyl groups having 6 to 22 carbon atoms, for example, benzenesulfonyl, etc.),Alkylsilyl groups (preferably alkylsilyl groups having 1 to 20 carbon atoms, e.g., monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl, etc.), arylsilyl groups (preferably arylsilyl groups having 6 to 42 carbon atoms, e.g., triphenylsilyl, etc.), alkoxysilyl groups (preferably alkoxysilyl groups having 1 to 20 carbon atoms, e.g., monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl, etc.), aryloxysilyl groups (preferably aryloxysilyl groups having 6 to 42 carbon atoms, e.g., triphenyloxysilyl, etc.), phosphoryl groups (preferably phosphate groups having 0 to 20 carbon atoms, e.g., -OP(=O)(R, P 2) A phosphonyl group (preferably a phosphonyl group having 0 to 20 carbon atoms, for example, -P(=O)(R P 2) A phosphenyl group (preferably a phosphenyl group having 0 to 20 carbon atoms, for example, -P(R P 2) A phosphonic acid group (preferably a phosphonic acid group having 0 to 20 carbon atoms, for example, -PO(OR P 2) 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.). P is 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 the substituent Z mentioned above. The alkyl groups, alkylene groups, alkenyl groups, alkenylene groups, alkynyl groups and / or alkynylene groups mentioned above may be cyclic or linear, and may be linear or branched.

[0130] Chain polymers can be synthesized by selecting raw material compounds and polymerizing them using known methods. Similarly, the method for synthesizing block polymers is not particularly limited, and known methods can be employed. For example, living radical polymerization is one such method. Examples of living radical polymerization include atom transfer radical polymerization (ATRP), reversible irreversible chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP). There are no particular limitations on the method of incorporating functional groups. Examples include copolymerizing a compound having a functional group selected from functional group (a), using a polymerization initiator or chain transfer agent having (or producing) the above-mentioned functional group, utilizing polymer reactions, ene reactions to double bonds, ene-thiol reactions, or ATRP (Atom Transfer Radical Polymerization) polymerization using a copper catalyst. In addition, functional groups can be introduced by using functional groups present in the main chain, side chains, or terminals of the polymer as reaction sites. For example, a compound having a functional group can be used to introduce a functional group selected from functional group (a) through various reactions with carboxylic acid anhydride groups in the polymer chain.

[0131] Specific examples of polymers constituting the polymer binder include polymers C-1 to C-14 shown below, and each polymer synthesized in the examples, but the present invention is not limited to these. In the chemical formulas of the polymers below, if the blocks are A and B, "A-block-B" is a notation based on the basic nomenclature of copolymer raw materials, and "-block-" indicates that it is a block polymer consisting of a block of component A and a block of component B. In the chemical formulas below, the number in the lower right of each component represents the content (mass%) in the polymer, and Me represents a methyl group.

[0132] [ka]

[0133] The polymer binder (B) contained in the electrode composition of the present invention may be one type or two or more types.

[0134] The content of the polymer binder (B) in the electrode composition is preferably 0.1 to 10% by mass, more preferably 0.3 to 8% by mass, even more preferably 0.5 to 7% by mass, and particularly preferably 0.5 to 3% by mass, based on dispersion characteristics, adhesion of solid particles, and cycle characteristics. In the present invention, at a solid content of 100% by mass, the mass ratio of the total mass of inorganic solid electrolyte and active material (total amount) to the total content of polymer binder [(mass of inorganic solid electrolyte + mass of active material) / (total mass of polymer binder)] is preferably in the range of 1,000 to 1. This ratio is more preferably 500 to 2, and even more preferably 100 to 10.

[0135] (Other polymer binders) The electrode composition of the present invention may contain one or more polymer binders other than the polymer binder (B) described above, for example, polymer binders that do not satisfy any of the above conditions (1) to (4) (also referred to as other polymer binders). Other polymer binders include, for example, polymer binders that exist (disperse) in the electrode composition as particulate matter without dissolving in the dispersion medium (particulate binders), and polymer binders with a high adsorption rate to conductive additives [A CA Examples include polymer binders with a content exceeding 50% (high-adsorption binders). The particle size of this particulate binder is preferably 1 to 1,000 nm. The particle size can be measured in the same manner as the particle size of the inorganic solid electrolyte described above. As for other polymer binders, various polymer binders used in the manufacture of all-solid-state secondary batteries can be used without particular limitation. The content of other polymer binders in the electrode composition is not particularly limited, but is preferably, for example, 0.01 to 4% by mass of 100% by mass of solids.

[0136] <Dispersion medium (D)> The electrode composition of the present invention contains a dispersion medium (D) that disperses or dissolves each of the above components. Such dispersion media can be any organic compound that is liquid in the environment in which it is used. Examples include various organic solvents, specifically alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic compounds, aliphatic compounds, nitrile compounds, ester compounds, and the like. 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 because it can exhibit excellent dispersion characteristics. A nonpolar dispersion medium generally refers to a medium with low affinity for water, and in the present invention, examples include ester compounds, ketone compounds, ether compounds, aromatic compounds, aliphatic compounds, and the like.

[0137] 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.

[0138] 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, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, etc.), alkylene glycol dialkyl ethers (ethylene glycol dimethyl ether, etc.), dialkyl ethers (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), and cyclic ethers (tetrahydrofuran, dioxane (including 1,2-, 1,3-, and 1,4- isomers), etc.).

[0139] 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, hexamethylphosphoric triamide, and the like.

[0140] Examples of amine compounds include triethylamine, diisopropylethylamine, tributylamine, and the like. Examples of ketone compounds include acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone, cyclohexanone, cycloheptanone, dipropyl ketone, dibutyl ketone, diisopropyl ketone, diisobutyl ketone (DIBK), isobutyl propyl ketone, sec-butyl propyl ketone, pentyl propyl ketone, butyl propyl ketone, and the like. Examples of aromatic compounds include benzene, toluene, xylene, perfluorotoluene, and the like. Examples of aliphatic compounds include hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane, decalin, paraffin, gasoline, naphtha, kerosene, gas oil, and the like. Examples of nitrile compounds include acetonitrile, propionitrile, isobutyronitrile, and the like. 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, isobutyl pivalate, and the like.

[0141] In the present invention, among others, an ether compound, a ketone compound, an aromatic compound, an aliphatic compound, and an ester compound are preferable, and an ester compound, a ketone compound, or an ether compound is more preferable.

[0142] The number of carbon atoms of the compound constituting the dispersion medium is not particularly limited, preferably 2 to 30, more preferably 4 to 20, still more preferably 6 to 15, and particularly preferably 7 to 12.

[0143] The dispersion medium is preferably low in polarity (low-polarity dispersion medium) from the viewpoint of dispersion characteristics, and further from the viewpoint of preventing deterioration (decomposition) of the sulfide-based inorganic solid electrolyte when using a sulfide-based inorganic solid electrolyte as the inorganic solid electrolyte. For example, the SP value (unit: MPa 1 / 2 ) can usually be set in the range of 15 to 27, preferably 17 to 22, more preferably 17.5 to 21, and still more preferably 18 to 20. The difference in SP value (absolute value, unit: MPa 1 / 2 ) between the SP value of the polymer binder (B) and the SP value of the dispersion medium (D) is not particularly limited, but is preferably 3.0 or less, more preferably 0 to 2.5, still more preferably from the viewpoint of further improving the dispersion characteristics. 0 to 2.0 is more preferable, and 0 to 1.7 is particularly preferable. When the electrode composition contains a plurality of types of polymer binders (B), the difference in SP value (absolute value) preferably includes the smallest value (absolute value) within the above range. The SP value of the dispersion medium is the value obtained by converting the SP value calculated by the above-mentioned Hoy method into units of MPa 1 / 2 . When the electrode composition contains two or more types of dispersion media, the SP value of the dispersion medium (D) means the SP value of the entire dispersion medium, and is the sum of the products of the SP value of each dispersion medium and the mass fraction. Specifically, it is calculated in the same manner as the above-described method for calculating the SP value of the polymer, except that the SP value of each dispersion medium is used instead of the SP value of the constituent components. The SP value of the dispersion medium (unit omitted) is shown below. In the following compound names, unless otherwise specified, the alkyl group means a normal alkyl group. MIBK (18.4), diisopropyl ether (16.8), dibutyl ether (17.9), diisopropyl ketone (17.9), DIBK (17.9), butyl butyrate (18.6), butyl acetate (18.9), toluene (18.5), xylene (a mixture of xylene isomers with a mixed molar ratio of ortho-isomer:para-isomer:metha-isomer = 1:5:2) (18.7), octane (16.9), ethylcyclohexane (17.1), cyclooctane (18.8), isobutyl ethyl ether (15.3), N-methylpyrrolidone (NMP, SP value: 25.4), perfluorotoluene (SP value: 13.4)

[0144] The boiling point of the dispersion medium at normal pressure (1 atmosphere) is not particularly limited, but is preferably 90°C or higher, and more preferably 120°C or higher. The upper limit is preferably 230°C or lower, and more preferably 200°C or lower.

[0145] The electrode composition of the present invention may contain one or more dispersion media. Examples of compositions containing two or more dispersion media include mixed xylene (a mixture of o-xylene, p-xylene, m-xylene, and ethylbenzene). 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.

[0146] <Lithium salts> The electrode composition of the present invention may also contain a lithium salt (supporting electrolyte). The lithium salt is preferably one 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, 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.

[0147] <Dispersant> The electrode composition of the present invention does not need to contain any dispersants other than the polymer binder (B) because the polymer binder (B) also functions as a dispersant. If the electrode composition contains a dispersant other than the polymer binder (B), a dispersant 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.

[0148] <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 commonly used binders, etc.

[0149] (Preparation of electrode composition) The electrode composition of the present invention can be prepared by conventional methods. Specifically, an inorganic solid electrolyte (SE), an active material (AC), a conductive additive (CA), a polymer binder (B), and a dispersion medium (D), and optionally a lithium salt and other components, can be mixed, for example, in 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, self-rotating mixers, and narrow-gap dispersers. The mixing conditions are not particularly limited. For example, the above components may be mixed all at once or sequentially. As for the mixing conditions, for example, the mixing temperature can be 15 to 40°C. Also, the rotation speed of a self-rotating mixer, etc., can be 200 to 3,000 rpm. The mixing atmosphere can be any of the following: air, dry air (dew point below -20°C), or in an inert gas (e.g., argon gas, helium gas, nitrogen gas). Since inorganic solid electrolytes react readily with moisture, mixing is preferably carried out in dry air or an inert gas.

[0150] [Electrode sheets for all-solid-state secondary batteries] The electrode sheet for all-solid-state secondary batteries of the present invention (sometimes simply referred to as an electrode sheet) is a sheet-like molded body capable of forming an active material layer or electrode (a laminate of an active material layer and a current collector) of an all-solid-state secondary battery, and includes various embodiments depending on its application.

[0151] The electrode sheet of the present invention has an active material layer composed of the electrode composition of the present invention described above. This active material layer is formed of components derived from the electrode composition (excluding the dispersion medium (D)), and is typically composed of solid particles (inorganic solid electrolyte (SE), active material (AC), and conductive additive (CA)) and polymer binder (B) that are in close contact (bound) together. In the present invention, the conductive additive (CA) present in the active material layer may exist as individual particles or as aggregates. In either case, it is preferable that the conductive additive (CA) has an average particle size of 10 μm or less. In this embodiment, in terms of sufficient construction of electron conduction paths (further reduction of battery resistance) and further improvement of cycle characteristics, the average particle size of the conductive additive (CA) present in the active material layer is more preferably less than 1.0 μm, even more preferably 0.5 μm or less, and particularly preferably 0.4 μm or less. The lower limit of this average particle size is not particularly limited, but for example, 0.05 μm is practical, preferably 0.06 μm or more, and more preferably 0.08 μm or more. In another preferred embodiment, the average particle size of the conductive additive (CA) is the same as in condition (4) above. The average particle size of the conductive additive (CA) present in the active material layer is determined as the arithmetic mean of the area-equivalent diameter of individual CA particles or aggregates in an SEM image obtained by observing an arbitrary cross-section of the active material layer with, for example, a scanning electron microscope (SEM). Specifically, the value obtained by the measurement method described in the examples below is used.

[0152] In the present invention, it is preferable that the active material layer has an electronic conductivity of 10 mS / cm or more. When an active material layer with an electronic conductivity of 10 mS / cm or more is incorporated into an all-solid-state secondary battery, the battery resistance can be reduced. In terms of further reducing battery resistance, it is more preferable that the electronic conductivity of the active material layer be 20 mS / cm or more, even more preferable that be 30 mS / cm or more, and particularly preferable that be 40 mS / cm or more. There is no particular upper limit to this electronic conductivity, but for example it can be 1,000 mS / cm, preferably 500 mS / cm or less, and more preferably 100 mS / cm or less. The electronic conductivity of the active material layer shall be the value obtained by the measurement method described in the examples below.

[0153] The electrode sheet of the present invention may be any electrode sheet having an active material layer composed of the electrode composition of the present invention as described above. The 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. This electrode sheet is usually a sheet having a substrate (current collector) and an active material layer, but embodiments having a substrate (current collector), an active material layer, and a solid electrolyte layer in that order are also included, as well as embodiments having a substrate (current collector), an active material layer, a solid electrolyte layer, and an active material layer in that order. Furthermore, the electrode sheet may have other layers besides those described above. Examples of other layers include a protective layer (release sheet), a coating layer, and so on.

[0154] The substrate is not particularly limited as long as it can support the 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.

[0155] At least one of the active material layers of the electrode sheet is formed from the electrode composition of the present invention. The content of each component in the active material layer formed from the electrode composition of the present invention is not particularly limited, but preferably it is the same as 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. In the present invention, each layer constituting the sheet for the all-solid-state secondary battery may be a single-layer structure or a multi-layer structure. If the solid electrolyte layer or active material layer is not formed with the electrode composition of the present invention, it will be formed with a conventional constituent layer forming material.

[0156] The electrode sheet of the present invention has an active material layer formed of the electrode composition of the present invention, and has an active material layer to which solid particles containing a conductive additive (CA) with an average particle size of 10 μm or less, preferably less than 1.0 μm, are bound, while suppressing an increase in the interfacial resistance of the solid particles. Therefore, by using the electrode sheet for all-solid-state secondary batteries of the present invention as the active material layer of an all-solid-state secondary battery, it is possible to realize an all-solid-state secondary battery that exhibits low resistance and excellent cycle characteristics. Furthermore, in an electrode sheet for all-solid-state secondary batteries in which the active material layer is formed on a current collector, the active material layer and the current collector can be firmly adhered together. Thus, the electrode sheet for all-solid-state secondary batteries of the present invention is suitably used as a sheet-like member that forms the active material layer, preferably the electrode, of an all-solid-state secondary battery (it is incorporated as an active material layer or electrode).

[0157] [Manufacturing method for electrode sheets for all-solid-state secondary batteries] The manufacturing method of the electrode sheet for all-solid-state secondary batteries of the present invention is not particularly limited, and it can be manufactured by forming an active material layer using the electrode composition of the present invention. For example, a method of forming a layer (coating and drying layer) made of the electrode composition by film-forming (coating and drying) the electrode composition of the present invention on the surface of a base material such as a current collector (which may be via other layers) can be mentioned. Thereby, an electrode sheet for all-solid-state secondary batteries having a base material and a coating and drying layer can be produced. Here, the coating and drying layer refers to a layer formed by coating the electrode composition of the present invention and drying the dispersion medium (that is, a layer made of the electrode composition of the present invention and having a composition obtained by removing the dispersion medium from the electrode composition of the present invention). The active material layer and the coating and drying layer may have a residual dispersion medium as long as the effects of the present invention are not impaired, and the residual amount can be, for example, 3% by mass or less in the coating and drying layer. In the manufacturing method of the electrode sheet for all-solid-state secondary batteries of the present invention, each process such as coating and drying will be described in the manufacturing method of the following all-solid-state secondary batteries.

[0158] Thus, an electrode sheet for all-solid-state secondary batteries having an active material layer composed of a coating and drying layer or an active material layer produced by appropriately pressurizing the coating and drying layer can be produced. The pressurization conditions and the like will be described in the manufacturing method of all-solid-state secondary batteries, which will be described later. Also, in the manufacturing method of the electrode sheet for all-solid-state secondary batteries of the present invention, it is also possible to peel off a base material, a protective layer (especially a release sheet), etc.

[0159] [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. In a preferred all-solid-state secondary battery, 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 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.

[0160] In the all-solid-state secondary battery of the present invention, at least one layer of the negative electrode active material layer and the positive electrode active material layer is formed of the electrode composition of the present invention, and it is preferable that at least the positive electrode active material layer is formed of the electrode composition of the present invention. It is also a preferred embodiment that both the negative electrode active material layer and the positive electrode active material layer are formed of the electrode composition of the present invention. Furthermore, with respect to the negative electrode (a laminate of negative electrode current collectors and positive electrode current collectors) and the positive electrode (a laminate of positive electrode current collectors and positive electrode current collectors), it is preferable that either one, preferably the positive electrode, is formed of the electrode sheet for all-solid-state secondary batteries of the present invention, and it is also a preferred embodiment that both are formed of the electrode sheet for all-solid-state secondary batteries of the present invention. The active 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. If the active material layer is not formed using the electrode composition of the present invention, the active material layer and the solid electrolyte layer can be manufactured using known materials.

[0161] <Positive electrode active material layer and negative electrode active material layer> The thickness of the negative electrode active material layer and the positive electrode active material layer are not particularly limited. Considering the dimensions of a typical all-solid-state secondary battery, the thickness of each layer is preferably 10 to 1,000 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. The active material layer having the above thickness may be a single layer (single coating of the electrode composition) or a multi-layer layer (multiple coatings of the electrode composition). However, forming a single layer of active material with a large thickness using the electrode composition of the present invention, which allows for thickening by increasing the concentration, is preferable in terms of resistance reduction and productivity. The thickness of the thickened single layer of active material that can be preferably formed with the electrode composition of the present invention can be, for example, 70 μm or more, and can even be 100 μm or more. When the negative electrode active material layer or the positive electrode active material layer is formed of the electrode composition of the present invention, each active material layer is the same as the active material layer in the electrode sheet for all-solid-state secondary batteries of the present invention.

[0162] <Solid electrolyte layer> The solid electrolyte layer is formed using a known material capable of forming a solid electrolyte layer for an all-solid-state secondary battery, and is the same as the solid electrolyte of an all-solid-state secondary battery. Its thickness is not particularly limited, but is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm.

[0163] <Current collector> The positive electrode active material layer and the negative electrode active material layer are preferably each provided with a current collector on the side opposite to the solid electrolyte layer. Electron conductors are preferred as such positive electrode and negative electrode current collectors. 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 materials for forming the positive electrode current collector, in addition to aluminum, aluminum alloys, stainless steel, nickel, and titanium, materials in which carbon, nickel, titanium, or silver has been treated on the surface of aluminum or stainless steel (with a thin film formed) are preferred, and among these, aluminum and aluminum alloys are more preferred. As materials for forming the negative electrode current collector, in addition to aluminum, copper, copper alloys, stainless steel, nickel, and titanium, materials in which carbon, nickel, titanium, or silver has been treated on the surface of aluminum, copper, copper alloys, or stainless steel are preferred, and aluminum, copper, copper alloys, and stainless steel are more preferred.

[0164] While current collectors are typically made of film sheets, other forms such as nets, punched materials, laths, 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. Furthermore, it is preferable to create an uneven surface on the current collector surface through surface treatment.

[0165] <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.

[0166] <Enclosure> 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 its current form, depending on the application. However, to form 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 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.

[0167] <Preferred Embodiment of All-Solid-State Rechargeable 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.

[0168] 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. In this embodiment, the all-solid-state secondary battery 10 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 are released. + 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.

[0169] When an all-solid-state secondary battery having the layer configuration shown in Figure 1 is placed in a 2032-type coin case, this all-solid-state secondary battery is sometimes referred to as an all-solid-state secondary battery laminate, and the battery made by placing this all-solid-state secondary battery laminate in a 2032-type coin case is sometimes referred to as a (coin-type) all-solid-state secondary battery.

[0170] (Solid electrolyte layer) The solid electrolyte layer can be any of those used in conventional all-solid-state secondary batteries without any particular limitations. This solid electrolyte layer contains an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, and optionally any of the above-mentioned components, and usually does not contain an active material.

[0171] (Positive electrode active material layer and negative electrode active material layer) In the all-solid-state secondary battery 10, both the positive electrode active material layer and the negative electrode active material layer are formed from the electrode composition of the present invention. Preferably, the positive electrode, formed by laminating the positive electrode active material layer and the positive electrode current collector, and the negative electrode, formed by laminating the negative electrode active material layer and the negative electrode current collector, are formed from the electrode sheet of the present invention to which the current collector is applied as a substrate. The positive electrode active material layer contains an inorganic solid electrolyte (SE) having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a positive electrode active material, a polymer binder (B), a conductive additive (CA), and any of the above-mentioned components, to the extent that they do not impair the effects of the present invention. The negative electrode active material layer contains an inorganic solid electrolyte (SE) having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a negative electrode active material, a polymer binder (B), a conductive additive (CA), and any of the above-mentioned components, etc., within a range that does not impair the effects of the present invention. In the all-solid-state secondary battery 10, the negative electrode active material layer can be a lithium metal layer. Examples of the lithium metal layer include a layer 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 above-mentioned thickness of the negative electrode active material layer.

[0172] Each component contained in the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2, particularly the inorganic solid electrolyte, the conductive additive, and the polymer binder, may be of the same type or different types.

[0173] In the present invention, by forming the active material layer with the electrodes of the present invention, an all-solid-state secondary battery with low resistance and excellent cycle characteristics can be realized.

[0174] (Current collector) The positive electrode current collector 5 and the negative electrode current collector 1 are as described above.

[0175] In the above-described all-solid-state secondary battery 10, if it has constituent layers other than those formed with the electrode composition of the present invention, layers formed with known constituent layer forming materials can also be applied. Furthermore, each layer may consist of a single layer or multiple layers.

[0176] [Manufacturing of all-solid-state rechargeable batteries] All-solid-state secondary batteries can be manufactured by conventional methods. Specifically, all-solid-state secondary batteries can be manufactured by forming at least one active material layer using the electrode composition of the present invention, and forming a solid electrolyte layer, and optionally the other active material layer or electrodes, using known materials. 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 the step of applying the electrode composition of the present invention to the surface of a substrate (for example, a metal foil that will serve as a current collector) and drying it to form a coating film (film formation). For example, a positive electrode sheet for an all-solid-state secondary battery is fabricated by applying an electrode composition containing a positive electrode active material as the positive electrode material (positive electrode composition) onto a metal foil, which serves as the positive electrode current collector, to form a positive electrode active material layer. Next, an inorganic solid electrolyte-containing composition for forming a solid electrolyte layer is applied on top of this positive electrode active material layer to form a solid electrolyte layer. Furthermore, an electrode composition containing a negative electrode active material is applied on top of the solid electrolyte layer as the negative electrode material (negative electrode composition) to form a negative electrode active material layer. By stacking a negative electrode current collector (metal foil) on top of the negative electrode active material layer, an all-solid-state secondary battery can be obtained in which a solid electrolyte layer is sandwiched between the positive electrode active material layer and the negative electrode active material layer. This can also be enclosed in a housing to create a desired all-solid-state secondary battery. Furthermore, by reversing the formation method of each layer, a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer can be formed on a negative electrode current collector, and a positive electrode current collector can be stacked on top to manufacture an all-solid-state secondary battery.

[0177] Another method is as follows: A positive electrode sheet for an all-solid-state secondary battery is manufactured as described above. A negative electrode active material layer is formed by coating a metal foil, which is the negative electrode current collector, with an electrode composition containing a negative electrode active material (negative electrode composition) to form a negative electrode active material layer, thereby manufacturing 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 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. 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 positive electrode sheet and the negative electrode sheet for an all-solid-state secondary battery are laminated so as to sandwich the solid electrolyte layer peeled from the substrate. In this way, an all-solid-state secondary battery can be manufactured.

[0178] 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 and the solid electrolyte sheet 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 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.

[0179] The active material layer, etc., can be formed, for example, by pressurizing an electrode composition, etc., on a substrate or active material layer under the pressurizing conditions described later, or a sheet molded body of a solid electrolyte or active material can be used. 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, or it may be used for both the positive electrode composition and the negative electrode composition.

[0180] <Formation of each layer (film deposition)> The application method for each composition is not particularly limited and can be selected as appropriate. Examples of wet application methods include coating (preferably wet coating), spray coating, spin coating, dip coating, slit coating, stripe coating, and bar coating. The application temperature is not particularly limited and is typically in a temperature range of around room temperature (e.g., 15-30°C) under non-heating conditions. The coated composition is preferably subjected to a drying treatment (heat treatment). The drying treatment may be performed after each individual coating of the composition, or after multi-layer coating. The drying temperature is not particularly limited as long as the dispersion medium can be removed, and is set appropriately according to the boiling point of the dispersion medium, etc. For example, the lower limit of the drying temperature 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 within this temperature range, the dispersion medium can be removed, and the material can be converted into a solid state (coated and dried layer). This is also preferable because it avoids excessively high temperatures and thus prevents damage to each component of the all-solid-state secondary battery. When the electrode composition of the present invention is coated and dried in this manner, variations in the contact state can be suppressed, solid particles can be bound together, and a coated and dried layer with a flat surface can be formed.

[0181] It is preferable to apply pressure to each layer or to the all-solid-state secondary battery after applying each composition, stacking the constituent layers, or after manufacturing the all-solid-state secondary battery. It is also preferable to apply pressure to the layers while they are stacked. Examples of pressurizing methods include hydraulic cylinder presses. The applied pressure is not particularly limited, but is generally preferably in the range of 5 to 1500 MPa. Furthermore, each applied composition may be heated simultaneously with pressurization. The heating temperature is not particularly limited, but is generally in the range of 30 to 300°C. Pressing can also be done at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. It can also be done at a temperature higher than the glass transition temperature of the polymer constituting the polymer binder. However, generally, the temperature should not exceed the melting point of the polymer. Pressurization may be performed after the coating solvent or dispersion medium has been dried beforehand, or it may be performed while the solvent or dispersion medium is still present. The compositions may be applied simultaneously, or the application, drying, and pressing may be performed simultaneously and / or sequentially. They may also be applied to separate substrates and then laminated by transfer.

[0182] The atmosphere used in the film formation method (coating, drying, and pressurizing under heating) is not particularly limited and may be any of the following: open air, dry air (dew point below -20°C), or in an inert gas (e.g., argon, helium, or nitrogen). The pressing time may be short (e.g., within a few hours) and high pressure may be applied, or it may be long (more than a day) and moderate pressure may be applied. For applications other than electrode sheets for all-solid-state secondary batteries, such as all-solid-state secondary batteries, a restraining device for all-solid-state secondary batteries (such as screw tightening pressure) may be used to maintain moderate pressure. The pressing pressure may be uniform or uneven 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. It is also possible to apply different pressures to the same area in stages. The pressed surface may be smooth or roughened.

[0183] <Initialization> It is preferable to initialize the all-solid-state secondary battery manufactured as described above after manufacturing or before use. Initialization is not particularly limited and can be performed, for example, by performing the initial charge and discharge under increased press pressure, and then releasing the pressure until it reaches the general operating pressure of the all-solid-state secondary battery.

[0184] [Applications of all-solid-state rechargeable batteries] The all-solid-state secondary battery of the present invention can be applied to a variety of uses. There are no particular limitations on the applications, but examples of applications when mounted on electronic devices include laptop 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. [Examples]

[0185] 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 composition are by mass unless otherwise specified. In the present invention, "room temperature" means 25°C.

[0186] 1. Polymer synthesis Polymers B-1 to B-21, shown in the chemical formulas below, were synthesized as follows, and binder solutions or dispersions B-1 to B-21 containing each polymer were prepared.

[0187] [Synthesis Example B-1] Synthesis of polymer B-1 and preparation of binder solution B-1 In a 100 mL volumetric flask, 90 g of dodecyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 10 g of 2-methoxyethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 3.6 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in 36 g of butyl butyrate to prepare a monomer solution. In a 300 mL three-necked flask, 18 g of butyl butyrate was added and stirred at 80°C, to which the monomer solution was added dropwise over 2 hours. After the dropwise addition was complete, the temperature was raised to 90°C and stirred for 2 hours to synthesize polymer B-1 (acrylic polymer). The obtained solution was reprecipitated in methanol and redissolved in xylene. Thus, an acrylic polymer B-1 with a mass-average molecular weight of 400,000 was synthesized, and a binder solution B-1 (10% by mass) made from this polymer was prepared.

[0188] [Synthesis Example B-2] Synthesis of Polymer B-2 and Preparation of Binder Solution B-2 In a nitrogen-purged and dried pressure vessel, 300 g of cyclohexane was charged as the solvent and 1.0 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, 15.5 g of styrene was added and polymerization was carried out for 2 hours. Subsequently, 24.0 g of 1,3-butadiene and 45.0 g of ethylene were added and polymerization was carried out for 3 hours, and then 15.5 g of styrene was added and polymerization was carried out for 2 hours. The resulting solution was reprecipitation in methanol, and the resulting solid was dried to obtain 100 parts by mass of polymer. To this, 3 parts by mass of 2,6-di-t-butyl-p-cresol was added and the reaction was carried out at 180°C for 5 hours. The resulting solution was reprecipitation in acetonitrile, and the resulting solid was dried at 80°C to obtain the polymer (dry product). Subsequently, the entire amount of the polymer obtained above was dissolved in 400 parts by mass of cyclohexane in a pressure vessel. Then, 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 release of pressure, the palladium carbon was removed by filtration, the filtrate was concentrated, and further vacuum-dried to obtain hydrocarbon polymer B-2. Subsequently, binder solution B-2 (10% by mass) was prepared by dissolving it in xylene.

[0189] [Synthesis Example B-3] Synthesis of Polymer B-3 and Preparation of Binder Solution B-3 In an autoclave, 100 parts by mass of deionized water, 64 parts by mass of vinylidene fluoride, 17 parts by mass of hexafluoropropene, and 19 parts by mass of tetrafluoroethylene were added. Furthermore, 1 part by mass of the polymerization initiator perloyl IPP (trade name, chemical name: diisopropyl peroxydicarbonate, manufactured by Nippon Oil & Fats Co., Ltd.) was added, and the mixture was stirred at 40°C for 24 hours. After stirring, the precipitate was filtered and dried at 100°C for 10 hours. To 10 parts by mass of the obtained polymer, 150 parts by mass of toluene or N-methylpyrrolidone was added and dissolved. Thus, a random copolymer fluoropolymer B-3 was synthesized, and a binder solution B-3 (10% by mass) consisting of this polymer was prepared.

[0190] [Synthesis Example B-4] Synthesis of polymer B-4 and preparation of binder solution B-4 In a 100 mL volumetric flask, 9.9 g of methyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 90 g of dodecyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.07 g of maleic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.03 g of monomethyl maleate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 3.6 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in 36 g of butyl butyrate to prepare a monomer solution. In a 300 mL three-necked flask, 18 g of butyl butyrate was added and stirred at 80°C, to which the monomer solution was added dropwise over 2 hours. After the dropwise addition was complete, the temperature was raised to 90°C and stirred for 2 hours to synthesize polymer B-4 (acrylic polymer). The obtained solution was reprecipitation in acetonitrile and redissolved in xylene. Thus, an acrylic polymer B-4 with a mass-average molecular weight of 400,000 was synthesized, and a binder solution B-4 (concentration 10% by mass) made from this polymer was prepared.

[0191] [Synthesis Examples B-5~9, 11, 12, 14 and 19] Synthesis of polymers B-5~9, 11, 12, 14 and 19 and preparation of binder solutions B-5~9, 11, 12, 14 and 19 Acrylic polymers B-5 to 9, 11, 12, 14, and 19 were synthesized in the same manner as in Synthesis Example B-4, except that compounds were used to derive each component so that the structure and composition (content of constituent components) shown in the following structural formula were obtained. Binder solutions B-5 to 9, 11, 12, 14, and 19 (10% by mass concentration) consisting of each polymer were then prepared.

[0192] [Synthesis Example B-10] Synthesis of polymer B-10 and preparation of binder dispersion B-10 In a 1L graduated cylinder, 200g of n-butyl acrylate, 200g of methacrylic acid, 16.5g of 3-mercaptopropionic acid, and 7.8g of polymerization initiator V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred to dissolve uniformly and prepare a monomer solution. In a 2L three-necked flask, 465.5g of toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and stirred at 80°C, and the above monomer solution was added dropwise over 2 hours. After the dropwise addition was complete, the mixture was stirred at 80°C for 2 hours, then the temperature was raised to 90°C and stirred for 2 hours. Next, 275mg of 2,2,6,6-tetramethylpiperidine-1-oxyl (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 27.5g of glycidyl methacrylate (manufactured by Tokyo Chemical Industries, Ltd.), and 5.5g of tetrabutylammonium bromide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and stirred at 120°C for 3 hours. After allowing the solution to stand at room temperature, it was poured into 1800 g of methanol, and the supernatant was removed. Butyl butyrate was then added, and the methanol was removed under reduced pressure to obtain a butyl butyrate solution of macromonomer M-1 (number average molecular weight 12,000). The solid content concentration was 49% by mass. A monomer solution was prepared by adding 28.8 g of methoxyethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1.40 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to a 100 mL graduated cylinder and dissolving it in 28.8 g of butyl butyrate. In a 300 mL three-necked flask, 19.6 g of macromonomer M-1 solution and 36.0 g of butyl butyrate were added and stirred at 80°C. The monomer solution was then added dropwise over 2 hours. After the addition was complete, the temperature was raised to 90°C and stirred for 2 hours. Subsequently, the acrylic polymer B-10 was mixed with xylene and dispersed into particles to prepare a binder dispersion B-10 (concentration 10% by mass). The average particle size in the dispersion of acrylic polymer B-10 was 200 nm.

[0193] [Synthesis Example B-13] Synthesis of polymer B-13 and preparation of binder solution B-13 Acrylic polymer B-13 was synthesized in the same manner as in synthesis example B-1, except that 99.7 g of dodecyl acrylate and 0.3 g of methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) were used instead of 90 g of dodecyl acrylate and 2-methoxyethyl acrylate, and binder solution B-13 (concentration 10% by mass) was prepared.

[0194] [Synthesis Example B-15] Synthesis of polymer B-15 and preparation of binder solution B-15 Acrylic polymer B-15 was synthesized in the same manner as in Synthesis Example B-1, except that 0.5 g of AS-6 (trade name, styrene macromonomer, number average molecular weight 6000, manufactured by Toagosei Co., Ltd.) was used and 9.5 g of 2-methoxyethyl acrylate was added. A binder solution B-15 (concentration 10% by mass) made from this polymer was then prepared.

[0195] [Synthesis Example B-16] Synthesis of polymer B-16 and preparation of binder solution B-16 In a 100 mL volumetric flask, 2.7 g of 2-hydroxyethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.1 g of monomethyl maleate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.2 g of maleic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.), 77 g of dodecyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 1.8 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in 36 g of butyl butyrate to prepare a monomer solution. In a 300 mL three-necked flask, 18 g of butyl butyrate was added and stirred at 80°C, and the monomer solution was added dropwise over 2 hours. After the dropwise addition was complete, the temperature was raised to 90°C and stirred for 2 hours. Then, 20 g of methyl methacrylate and 1.8 g of polymerization initiator V-601 were added and stirred at 90°C for 2 hours. The resulting solution was reprecipitation in acetonitrile and redissolved in xylene. Thus, an ABA-type block polymer, acrylic polymer B-16, was synthesized, and a binder solution B-16 (10% by mass) made from this polymer was prepared.

[0196] [Synthesis Example B-17] Synthesis of polymer B-17 and preparation of binder solution B-17 Acrylic polymer B-17 was synthesized in the same manner as in synthesis example B-1, except that 97 g of dodecyl acrylate, 2.7 g of 2-hydroxyethyl methacrylate, 0.1 g of monomethyl maleate, and 0.2 g of maleic anhydride were used. A binder solution B-17 (10% by mass) consisting of this polymer was then prepared.

[0197] [Synthesis Example B-18] Synthesis of polymer B-18 and preparation of binder solution B-18 Macromonomer M-2 (number-average molecular weight 15,000) was synthesized in the same manner as in the synthesis example of macromonomer M-1, except that 420 g of dodecyl acrylate, 40 g of maleic anhydride, and 40 g of monomethyl maleate were used instead of n-butyl acrylate and methacrylic acid in the synthesis of macromonomer M-1 in synthesis example B-10. Acrylic polymer B-18 was synthesized in the same manner as in synthesis example B-10, except that 72 g of dodecyl acrylate and 3 g of 2-hydroxyethyl methacrylate were used instead of methoxyethyl methacrylate, and 25 g (solid content) of macromonomer M-2 was used instead of macromonomer M-1 solution. A binder solution B-18 (10% by mass) consisting of this polymer was then prepared.

[0198] [Synthesis Example B-20] Synthesis of polymer B-20 and preparation of binder solution B-20 Acrylic polymer B-20 was synthesized in the same manner as in synthesis example B-1, except that 90 g of dodecyl acrylate, 9.91 g of methyl methacrylate, and 0.09 g of monomethyl maleate were used. A binder solution B-20 (10% by mass) consisting of this polymer was then prepared.

[0199] [Synthesis Example B-21] Synthesis of polymer B-21 and preparation of binder solution B-21 Acrylic polymer B-21 was synthesized in the same manner as in synthesis example B-1, except that 84.7 g of dodecyl acrylate, 15 g of styrene, and 0.3 g of monomethyl maleate were used. A binder solution B-21 (10% by mass) consisting of this polymer was then prepared.

[0200] The synthesized polymers are shown below. Polymer B-16 is a block polymer and is denoted in the same way as above. The numbers in the lower right corner of each component indicate the content (mass %), and in polymer B-4, etc., x is the value that satisfies the "content of functional group (a)" described in Table 1, while in polymer B-16, it is a value to indicate the ratio of the content of both end blocks. In the structural formulas below, Me represents a methyl group.

[0201] [ka]

[0202] [ka]

[0203] [ka]

[0204] The mass-average molecular weight (Mw) and SP value of each synthesized polymer were calculated using the method described above. These results are shown in Table 1. The unit of the SP value is "MPa". 1 / 2 However, units are omitted in the table. In Table 1, "Content (mass%)" indicates the content of each functional group as the content of the functional group-containing component in polymer (b). Furthermore, since polymer B-18 has one functional group-containing component that contains both a carboxyl group and a carboxylic anhydride group as functional group (a), the content of functional group (a) is expressed as the content of the above-mentioned one functional group-containing component in polymer (b). In Table 1, the "x" in the above chemical formulas was added. However, since polymer B-16 is unknown, it is indicated with "-" in the corresponding column.

[0205] [Table 1]

[0206] 2. Synthesis of sulfide-based inorganic solid electrolytes [Synthesis example S] The sulfide-based inorganic solid electrolyte was synthesized with reference to non-patent literature: 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, 2.42 g of lithium sulfide (Li2S, Aldrich, purity >99.98%) and 3.90 g of phosphorus pentasulfide (P2S5, Aldrich, purity >99%) were weighed out in a glove box under an argon atmosphere (dew point -70°C), placed in an agate mortar, and mixed for 5 minutes using an agate pestle. The mixing ratio of Li2S to P2S5 was 75:25 molar ratio. Next, 66 g of 5 mm diameter zirconia beads were placed in a 45 mL zirconia container (manufactured by Fritsch), and the entire amount of the above-mentioned mixture of lithium sulfide and phosphorus pentasulfide was added. The container was then completely sealed under an argon atmosphere. The container was set in a planetary ball mill P-7 (trade name, manufactured by Fritsch), and mechanical milling (atomization) was performed at a temperature of 25°C and a rotation speed of 510 rpm for 24 hours to obtain 6.20 g of yellow powder sulfide-based inorganic solid electrolyte (Li-PS glass, hereinafter sometimes referred to as LPS). In this way, inorganic solid electrolyte LPS with a particle size of 5 μm was synthesized.

[0207] [Example 1] <Preparation of the positive electrode composition (slurry)> In a container for a rotary-rotating mixer (ARE-310, manufactured by Thinky Co., Ltd.), 2.8 g of the inorganic solid electrolyte (SE) shown in Table 2-1 below, and xylene in the following isomer mixing ratio as the dispersion medium (D) so that the dispersion medium (D) content in the positive electrode composition is 50% by mass were added. Then, this container was set in the rotary-rotating mixer ARE-310 (product name) and mixed for 2 minutes at a temperature of 25°C and a rotation speed of 2000 rpm. After that, LiNi was added to this container as the positive electrode active material (AC) in the proportions shown in Table 2-1. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NMC, manufactured by Aldrich), acetylene black (AB) as a conductive additive (CA), and a binder solution (B) or binder dispersion (referred to as "binder solution or dispersion" in Table 2-1) were added. The mixture was then placed in an ARE-310 (product name) rotary mixer and mixed for 2 minutes at 25°C and 2000 rpm to prepare positive electrode compositions (slurries) P-1 to P-24. The content of the binder solution or dispersion is the content in the solid content.

[0208] <Preparation of the negative electrode composition (slurry)> In a container for the ARE-310 rotary mixer, 2.8 g of the inorganic solid electrolyte (SE) shown in Table 3-1, 0.06 g (solid content mass) of the binder solution (B) or dispersion (referred to as "binder solution or dispersion" in Table 3-1) shown in Table 3-1, and xylene in the following isomer mixing ratio as the dispersion medium (D) so that the dispersion medium content in the negative electrode composition is 50% by mass were added. Then, this container was set in a ARE-310 rotary mixer (product name) manufactured by Thinky Co., Ltd., and mixed for 2 minutes at 25°C and a rotation speed of 2000 rpm. Subsequently, 3.11 g of silicon (Si, manufactured by Aldrich) was added as the negative electrode active material (AC) as shown in Table 3-1 below, and 0.25 g of acetylene black (AB) was added as the conductive additive (CA). These were then set in the ARE-310 (product name) autopilot mixer and mixed for 2 minutes at 25°C and 2000 rpm to prepare negative electrode compositions (slurries) N-1 to N-24, respectively. Furthermore, the negative electrode composition (slurry) N-19 uses 2.86 g of inorganic solid electrolyte (SE) and does not use binder solution (B).

[0209] The adsorption rate of the polymer binder (B) used in the preparation of the electrode composition to the conductive additive (CA) [A CA ] and adsorption rate to inorganic solid electrolytes (SE) [A SE The values ​​measured by the measurement methods described above are shown in Tables 2-2 and 3-2. Furthermore, the average particle size of the conductive additive (CA) when the polymer binder (B), dispersion medium (D), and conductive additive (CA) were mixed in the same mass ratio as the electrode composition (condition (4A)) was measured as follows. Specifically, the polymer binder (B), dispersion medium (D), and conductive additive (CA) used in the preparation of each electrode composition were mixed in the mass ratios shown in Table 2-1 or Table 3-1 to prepare the dispersion for measurement. The preparation conditions were a mix rotor (manufactured by AS ONE Corporation) at room temperature, a rotation speed of 50 rpm, and a stirring time of 3 hours. The obtained dispersion for measurement was subjected to 50 data acquisitions 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, and the obtained volume-average particle size was calculated. For other detailed conditions, etc., refer to the description in JIS Z 8828:2013 "Particle size analysis - Dynamic light scattering method" as needed. Five samples were prepared and measured for each level, and the average value was taken as the average particle size of the conductive additive (CA) (condition (4A)). The results are shown in the "Average Particle Size under Condition (4A)" column of Tables 2-2 and 3-2.

[0210] Furthermore, the SP value of the dispersion medium (D), and the difference ΔSP (absolute value) between the SP value of the dispersion medium (D) and the SP value of the polymer (b) forming the polymer binder (B) are calculated and shown in the respective tables. Furthermore, the solubility of polymers B-1 to B-9 and B-11 to B-21 synthesized above in the dispersion medium (D) was determined by measuring the transmittance for each combination of polymer binder (B) and dispersion medium (D) used in the preparation of the electrode compositions described in Tables 2-1 and 3-1 below. In all cases, the solubility was 10% by mass or more, and "Soluble" is indicated in the "Solubility" column of Tables 2-2 and 3-2. On the other hand, the solubility of polymer B-10 was less than 10% by mass, and "Particulate" is indicated in the "Solubility" column of Tables 2-2 and 3-2. Note that in each table, the units of content (mass%), SP value, and SP value difference ΔSP (MPa) are indicated. 1 / 2 The units for adsorption rate (%) and average particle size (μm) are omitted.

[0211] [Table 2-1]

[0212] [Table 2-2]

[0213] [Table 3-1]

[0214] [Table 3-2]

[0215] <Abbreviations in the table> NMC:LiLi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (manufactured by Aldrich, particle size 5 μm) LPS: LPS synthesized using synthesis example S AB: Acetylene Black (manufactured by Denka Co., Ltd., particle size 35 nm, bulk density 0.04 g / ml) AB2: Acetylene Black (manufactured by Denka Co., Ltd., particle size 48 nm, bulk density 0.15 g / ml) CB: Carbon Black SUPER-P Li (manufactured by IMERYS, particle size 40nm) Si: Silicon (manufactured by High Purity Chemical Laboratory Co., Ltd., particle size 5 μm) xylene isomer mixture with a molar ratio of ortho-isomer:para-isomer:meta-isomer = 1:5:2

[0216] <Fabrication of positive electrode sheets for all-solid-state secondary batteries> Each of the positive electrode compositions P-1 to P-24 obtained above was applied to a 20 μm thick aluminum foil using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.) at room temperature, and the positive electrode composition was dried (dispersion medium removed) by heating at 110°C for 1 hour. Subsequently, the dried positive electrode composition was pressurized at 25°C (10 MPa, 1 minute) using a heat press machine to produce positive electrode sheets P-1 to P-24 for all-solid-state secondary batteries, each having a positive electrode active material layer with a thickness of 100 μm.

[0217] <Fabrication of negative electrode sheets for all-solid-state secondary batteries> Each of the negative electrode compositions N-1 to N-24 obtained above was applied to a 20 μm thick copper foil using a Baker-type applicator (product name: SA-201) at room temperature, heated at 110°C for 1 hour, and then dried in a vacuum dryer AVO-200NS (product name, manufactured by AS ONE Corporation) at 110°C for 2 hours to dry the negative electrode composition (remove the dispersion medium). Subsequently, the dried negative electrode composition was pressurized at 25°C (10 MPa, 1 minute) using a heat press to produce negative electrode sheets N-1 to N-24 for all-solid-state secondary batteries, each having a negative electrode active material layer with a thickness of 70 μm.

[0218] Each manufactured composition and sheet was evaluated as described below, and the results are shown in Tables 4-1 and 4-2 (collectively referred to as Table 4).

[0219] <Evaluation 1: Dispersion Stability> Each prepared composition (slurry) was placed in a glass test tube with a diameter of 10 mm and a height of 4 cm, up to a height of 4 cm, and left to stand at 25°C for 24 hours. The percentage reduction in solid content of the top 25% (height) of the composition before and after standing was calculated using the following formula. The ease with which solid particles aggregate or settle over time was evaluated as the storage stability (dispersion stability) of the composition, based on which of the following evaluation criteria this percentage of solid content falls into. In this test, a smaller percentage of solid content reduction indicates better dispersion stability, and an evaluation of "F" or higher is considered a passing level. Solid content reduction rate (%) = [(Solid content concentration of the top 25% before standing - Solid content concentration of the top 25% after standing) / Solid content concentration of the top 25% before standing] × 100 - Evaluation Criteria - A: Solid content reduction rate <0.5% B: 0.5%≦Solid content reduction rate<2% C: 2%≦solid content reduction rate<5% D: 5%≦solid content reduction rate< 10% E: 10%≦solid content reduction rate< 15% F: 15%≦solid content reduction rate< 20% G: 20%≦solid content reduction rate

[0220] <Evaluation 2: Upper limit concentration for slurry formation> In preparing each of the above compositions (slurries), test compositions with a solid content concentration of 76% by mass were prepared by adjusting the amount of dispersion medium used. The prepared test composition with a solid content concentration of 76% by mass was placed in a container (a cylindrical container for a rotary mixer (product name: ARE-310, manufactured by Shinky Co., Ltd.) (diameter 5.0 cm, height 7.0 cm)) on a table to a height of approximately 1.0 cm. From this position, the container was tilted 60 degrees (relative to the vertical) and it was checked whether it had enough fluidity to sag (fluctuate) under its own weight within 10 seconds. If it did not sag (remained still) and did not have fluidity, the above dispersion medium was added to reduce the solid content concentration of the test composition by 1% by mass, and the mixture was dispersed in the above rotary mixer at 2,000 rpm for 1 minute. Then, the fluidity was checked again in the same manner as the test composition with a solid content concentration of 76% by mass. This process was repeated by decreasing the solid content concentration by 1% by mass increments. The maximum solid content concentration at which fluidity was maintained was defined as the upper limit concentration for slurry formation, and the maximum concentration of a concentrated slurry that could be prepared was evaluated. This test was conducted at 25°C. If the solid content concentration is increased beyond the upper limit for slurry formation, it becomes difficult to use the composition in the coating process. Therefore, the upper limit for slurry formation serves as an indicator of the upper limit for solid content concentration of a composition that can be used in the coating process, and a high value is preferable. In Table 4 below, the unit for the upper limit concentration for slurrying is mass%, but this is omitted here.

[0221] <Evaluation 3: Average particle size of conductive additive in the active material layer> The average particle size of the conductive additive in the active material layer of the fabricated positive electrode sheet and negative electrode sheet for all-solid-state secondary batteries was measured as follows, and the results are shown in Table 4. In Table 4, the unit of average particle size is μm, but it is omitted here. Specifically, the cross-sections obtained by vertically cutting the active material layer of each fabricated sheet were observed with a scanning electron microscope (SEM) at a magnification of 5,000x to obtain SEM images. Fifty conductive additives (single particles or aggregates) were arbitrarily selected from a 0.1 mm × 0.05 mm area in these SEM images, and the area equivalent diameter for each conductive additive was determined. The arithmetic mean of these values ​​was taken as the average particle size of the conductive additives (CA) present in the active material layer. In SEM images, the boundaries of conductive additives (CAs) can be identified by binarization. Note that if the conductive additives (CAs) form aggregates, the aggregates are treated as a single particle.

[0222] <Evaluation 4: Electronic conductivity of the active material layer> Table 4 shows the results of measuring the electronic conductivity in the active material layer of the fabricated positive electrode sheet and negative electrode sheet for all-solid-state secondary batteries, as described below. In Table 4, the unit of electronic conductivity is mS / cm, but it is omitted here. Specifically, an electrode sheet for a solid-state secondary battery was punched out into a 10mm diameter disc shape and placed in a PET cylinder with an inner diameter of 10mm. A 10mm SUS rod was inserted through the openings at both ends of the cylinder, and the current collector side and the active material layer side of the electrode sheet for the solid-state secondary battery were pressurized with the SUS rod at a pressure of 350MPa, and then fixed under a pressure of 50MPa. Constant voltage measurements were performed using an impedance analyzer (VMP-300, manufactured by Toyo Technica Co., Ltd.), and the current value I (mA) when a voltage of V = 5.0mV was applied was read, and the electron conductivity σ was calculated using the following formula. e The (mS / cm) value was calculated. The thickness of the active material layer was defined as D (μm). The thickness D of the positive electrode active material layer was 90 μm, and the thickness D of the negative electrode active material layer was 65 μm. σ e (mS / cm) = I / V / 0.0785 × D

[0223] [Table 4-1]

[0224] [Table 4-2]

[0225] <Manufacturing of all-solid-state rechargeable batteries> All-solid-state secondary batteries were manufactured using the combinations of constituent layers shown in Tables 5-1 and 5-2 (collectively referred to as Table 5) for the positive electrode sheet, the solid electrolyte sheet, and the negative electrode sheet. (Preparation of inorganic solid electrolyte-containing composition (slurry)) In a container for a rotary-rotating mixer (ARE-310, manufactured by Thinky Co., Ltd.), 2.8 g of LPS synthesized in the above synthesis example S, 0.08 g (solid content mass) of B-1 as a polymer binder, and butyl butyrate as the dispersion medium were added so that the dispersion medium content in the composition was 50% by mass. Then, this container was set in the rotary-rotating mixer ARE-310 (product name). Mixing was performed at 25°C and a rotation speed of 2000 rpm for 5 minutes to prepare an inorganic solid electrolyte-containing composition (slurry) S-1. The content of each component in the composition was 97.2% by mass for LPS and 2.8% by mass for the binder, based on 100% by mass of solids.

[0226] (Fabrication of solid electrolyte sheets for all-solid-state secondary batteries) Each inorganic solid electrolyte-containing composition S-1 obtained above was applied to a 20 μm thick aluminum foil using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.), and heated at 110°C for 2 hours to dry the inorganic solid electrolyte-containing composition (remove the dispersion medium). Subsequently, the dried inorganic solid electrolyte-containing composition was pressurized using a heat press machine at a pressure of 10 MPa at 25°C for 10 seconds to produce a solid electrolyte sheet S-1 for all-solid-state secondary batteries. The thickness of the solid electrolyte layer was 50 μm.

[0227] (Manufacturing of all-solid-state rechargeable batteries) The positive electrode sheet for all-solid-state secondary batteries shown in the "Positive Electrode Sheet No." column of Table 5 was punched out into a 10 mm diameter disc shape and placed in a PET cylinder with an inner diameter of 10 mm. A solid electrolyte sheet S-1 for all-solid-state secondary batteries was punched out into a 10 mm diameter disc shape and placed inside the cylinder on the positive electrode active material layer side, and 10 mm SUS rods were inserted from the openings at both ends of the cylinder (the positive electrode active material layer of the positive electrode sheet for all-solid-state secondary batteries and the solid electrolyte layer of the solid electrolyte sheet S-1 were in contact). The current collector side of the positive electrode sheet for all-solid-state secondary batteries and the aluminum foil side of the solid electrolyte sheet for all-solid-state secondary batteries were pressurized with a pressure of 350 MPa using the SUS rods. The SUS rod on the solid electrolyte sheet side for the all-solid-state secondary battery was temporarily removed, and the aluminum foil of the solid electrolyte sheet was gently peeled off. Then, the negative electrode sheet for the all-solid-state secondary battery shown in the "Negative Electrode Sheet No." column of Table 5 was punched out into a 10 mm diameter disc shape and inserted onto the solid electrolyte layer of the solid electrolyte sheet for the all-solid-state secondary battery inside the cylinder (the solid electrolyte layer of solid electrolyte sheet S-1 and the negative electrode active material layer of the negative electrode sheet for the all-solid-state secondary battery were in contact). The removed SUS rod was reinserted into the cylinder and fixed under a pressure of 50 MPa. In this way, all-solid-state secondary batteries No. C-1 to C-48 were obtained, having a laminated structure of aluminum foil (thickness 20 μm) - positive electrode active material layer (thickness 90 μm) - solid electrolyte layer (thickness 45 μm) - negative electrode active material layer (thickness 65 μm) - copper foil (thickness 20 μm).

[0228] <Evaluation 5: Cycle characteristics (discharge capacity retention rate) test> For each solid-state secondary battery manufactured, the discharge capacity retention rate was measured using the TOSCAT-3000 charge / discharge evaluation device (product name, manufactured by Toyo System Co., Ltd.). Specifically, each all-solid-state secondary battery was tested at a current density of 0.1 mA / cm² in an environment of 30°C. 2 The battery was charged until the voltage reached 3.6V. After that, the current density was 0.1mA / cm². 2 The battery was then discharged until the voltage reached 2.5V. This one charge and one discharge cycle was considered one charge-discharge cycle, and the same charge-discharge cycle was repeated three times under the same conditions to initialize the battery. After that, the current density was 3.0mA / cm². 2Charge the battery until the voltage reaches 3.6V, with a current density of 3.0mA / cm². 2 A high-speed charge-discharge cycle was defined as discharging until the battery voltage reached 2.5V, and this high-speed charge-discharge cycle was repeated 500 times. The discharge capacity of each all-solid-state secondary battery after the first high-speed charge-discharge cycle and after the 500th high-speed charge-discharge cycle was measured using a charge-discharge evaluation device: TOSCAT-3000 (product name). The discharge capacity retention rate was calculated using the following formula, and this discharge capacity retention rate was applied to the evaluation criteria below to evaluate the cycle characteristics of the all-solid-state secondary battery. In this test, an evaluation criterion of "F" or higher is considered a passing level. The results are shown in Table 5. Although all-solid-state secondary batteries C-4 and C-23 received an evaluation of F, their discharge capacity retention rate was 68%. Discharge capacity maintenance rate (%) = (Discharge capacity at 500 cycles / Discharge capacity at 1 cycle) × 100 In this test, a higher evaluation criterion indicates superior battery performance (cycle characteristics), and the ability to maintain initial battery performance even after multiple high-speed charge-discharge cycles (even during long-term use). Furthermore, the discharge capacity of the evaluation all-solid-state secondary battery of the present invention in the first cycle was sufficient for it to function as an all-solid-state secondary battery. In addition, even when performing a normal charge-discharge cycle under the same conditions as the initialization described above, rather than the high-speed charge-discharge described above, the evaluation all-solid-state secondary battery of the present invention maintained excellent cycle characteristics. - Evaluation Criteria - A: 90%≦Discharge capacity maintenance rate B: 85%≦Discharge capacity maintenance rate<90% C: 80%≦Discharge capacity maintenance rate<85% D: 75%≦Discharge capacity maintenance rate<80% E: 70%≦discharge capacity maintenance rate<75% F: 60%≦Discharge capacity maintenance rate<70% G: Discharge capacity maintenance rate<60%

[0229] [Table 5-1]

[0230] [Table 5-2]

[0231] The results shown in Tables 4 and 5 indicate the following: Electrode compositions P-19 and N-19 that do not contain the components specified in this invention, or electrode compositions that do not satisfy any of the conditions (1) to (4) specified in this invention, do not have sufficient storage stability. Therefore, the active material layer formed from these compositions has an average particle size of the conductive additive that is too large, or insufficient electronic conductivity, making it impossible to manufacture an all-solid-state secondary battery with excellent cycle characteristics. In contrast, electrode compositions containing an inorganic solid electrolyte (SE), an active material (AC), a conductive additive (CA), a dispersion medium (D), and a polymer binder (B), and satisfying conditions (1) to (4), all exhibit excellent dispersion stability even when the solid content concentration is increased. Active material layers using these electrode compositions contain small-particle conductive additives and exhibit high electronic conductivity, and all-solid-state secondary batteries equipped with this active material layer can achieve low resistance and excellent cycle characteristics.

[0232] 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.

[0233] This application claims priority based on Japanese Patent Application No. 2021-113028, filed in Japan on July 7, 2021, the contents of which are incorporated herein by reference as part of this specification. [Explanation of Symbols]

[0234] 1 Negative electrode current collector 2 Negative electrode active material layer 3 Solid electrolyte layer 4 Cathode active material layer 5 Positive electrode current collector 6. Operating parts 10 All-solid-state secondary battery

Claims

1. An electrode composition comprising 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), The polymer (b) constituting the polymer binder (B) is a (meth)acrylic polymer containing a functional group-containing component having at least one functional group (a1) selected from the following functional group group (a1), and a component having a substituent with 8 or more carbon atoms as a side chain, in the following amounts. An electrode composition in which the dispersion medium (D) is an ester compound, a ketone compound, an ether compound, an aromatic compound, or an aliphatic compound. (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 The percentage is greater than 0% and less than or equal to 50%. (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. <Total content of the functional group-containing component in the polymer (b)> 0.01 to 30% by mass, provided that the functional group-containing component does not include a component having a polymer chain incorporating a functional group (a1) selected from the following functional group group (a1) as a substituent, then 0.01 to 8% by mass. <Content of the constituent component having 8 or more carbon atoms in the polymer (b)> 60-99.9% by mass <Functional group (a1)> Hydroxyl group, carboxyl group, ether bond, aryl group and carboxylic anhydride group

2. The adsorption rate [A ＣＡ The electrode composition according to claim 1, wherein the amount of ] is 5% or more and less than 30%.

3. The adsorption rate of the polymer binder (B) to the inorganic solid electrolyte (SE) in the dispersion medium (D) [A ＳＥ The electrode composition according to claim 1, wherein 45% or less of ].

4. The electrode composition according to claim 1, wherein the mass-average molecular weight is 10,000 to 700,000.

5. The difference ΔSP between the SP value of the dispersion medium (D) and the SP value of the polymer (b) is 3.0 MPa. １／２ The electrode composition according to claim 1, which is as follows:

6. The electrode composition according to claim 1, wherein the inorganic solid electrolyte (SE) is a sulfide-based inorganic solid electrolyte.

7. An electrode sheet for an all-solid-state secondary battery having an active material layer formed from the electrode composition according to any one of claims 1 to 6.

8. The electrode sheet for an all-solid-state secondary battery according to claim 7, wherein the average particle size of the conductive additive (CA) in the active material layer is 0.5 μm or less.

9. The electrode sheet for an all-solid-state secondary battery according to claim 7, wherein the electronic conductivity of the active material layer is 30 mS / cm or more.

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, All-solid-state secondary battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer is an active material layer formed from the electrode composition described in any one of claims 1 to 6.

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 claims 1 to 6.

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 Claim 11.

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