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

Abstract

Provided are an electrode composition that can improve battery characteristics while suppressing the localization of a fibrous conductive auxiliary agent within an active material layer, even when the solid component concentration is increased above 75 mass%, an all-solid-state secondary battery electrode sheet and an all-solid-state secondary battery that use the electrode composition, a production method for the all-solid-state secondary battery electrode sheet, and a production method for the all-solid-state secondary battery.

Description

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

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

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

[0003] In all-solid-state secondary batteries, the constituent layers (solid electrolyte layer, negative electrode active material layer, positive electrode active material layer, etc.) are usually formed as layers of solid particles using a material in which solid particles such as inorganic solid electrolyte, active material, and conductive additive are dispersed in a dispersion medium. However, if solid particles in the constituent layers aggregate locally and exist in a non-uniform state (uneven distribution), current concentration and / or ion concentration occur locally in the inorganic solid electrolyte and / or active material during charging and discharging, making the inorganic solid electrolyte and / or active material more susceptible to degradation. As a result, this leads to a decrease in battery performance (also called battery characteristics), such as charge / discharge characteristics and life characteristics. Therefore, techniques to improve the dispersibility of solid particles in the materials forming the constituent layers have been studied. For example, Patent Document 1 specifically describes the positive electrode composition shown below. According to Patent Document 1, the following positive electrode composition exhibits excellent dispersion stability even when the solid content concentration is increased to 75% by mass, and when used as an active material forming material for all-solid-state secondary batteries, it is possible to suppress the increase in battery resistance and achieve excellent cycle characteristics. An electrode composition comprising an inorganic solid electrolyte (SE) having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a positive electrode active material (AC), acetylene black as a conductive additive (CA), a polymer binder (B), and a dispersion medium (D), satisfying the following conditions (1) to (4): (1) The polymer binder (B) is dissolved in the dispersion medium (D); (2) The adsorption rate of the polymer binder (B) to the conductive additive (CA) in the dispersion medium (D) [A ＣＡ (3) The mass-average molecular weight of the polymer constituting the polymer binder (B) is 6,000 or more. (4) The average particle size of the conductive additive (CA) present in the active material layer formed with the electrode composition is less than 1.0 μm.

[0004] In all-solid-state secondary batteries, the technique of using conductive additives in combination with the active material is widely used to sufficiently construct electron conduction paths in the active material layer and form a constituent layer with low resistance and high electron conductivity. Recently, in order to improve the electron conductivity of the active material layer and, consequently, improve the battery performance of all-solid-state secondary batteries, fibrous conductive additives have attracted attention among materials that function as conductive additives, and their use as conductive additives is being considered. However, conductive additives generally have inferior dispersibility in dispersion media compared to inorganic solid electrolytes, and the coexistence of conductive additives also adversely affects the overall dispersibility of the composition. Patent Document 2 specifically describes the negative electrode composition shown below. According to Patent Document 2, the negative electrode composition shown below exhibits excellent dispersion stability and handling properties even when containing a conductive additive, and when used as a material for forming the constituent layers of an all-solid-state secondary battery, it is said to enable the realization of an all-solid-state secondary battery with low resistance and excellent cycle characteristics. "A negative electrode composition having a solid content concentration of 52% by mass, comprising an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a negative electrode active material, carbon nanotubes as a conductive additive, a polymer binder, and a dispersion medium, wherein the polymer binder satisfies the following conditions [I] and [II]: [I] The polymer binder comprises a polymer having a component (A) having at least one functional group from a specific functional group group (a), and a component (X) having a polymer chain containing a polymer chain component (b) having at least one functional group from the following functional group group (a). [II] The polymer binder dissolves in the dispersion medium and has an adsorption rate of 50% or less to the conductive additive."

[0005] International Publication No. 2023 / 282333, International Publication No. 2023 / 282312

[0006] Incidentally, as described in Patent Document 1, in recent years, from the viewpoint 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 promoted. 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. Moreover, as mentioned above, among substances that function as conductive additives, fibrous conductive additives are strongly entangled (including entanglement within a single molecule and entanglement among multiple molecules) because of their fibrous nature. Therefore, it is difficult to untangle them and uniformly distribute (disperse) the fibrous conductive additive both within the composition and within the electrode, and localization is likely. Such localization due to aggregation of fibrous conductive additives is further worsened in high-concentration compositions.

[0007] As mentioned above, fibrous conductive additives are promising materials that can meet the demands of recent high-performance electric vehicles and the rapid progress of their practical application. However, they have a major problem in that they tend to aggregate and localize more easily than conventionally used particulate (spherical) conductive additives such as carbon black. Specifically, if the conductive additive aggregates and localizes in the active material layer of an all-solid-state secondary battery, even if the inorganic solid electrolyte and active material are uniformly distributed, localized current flow occurs in the active material layer during charging and discharging, leading to degradation of the active material and a decrease in battery performance such as charge-discharge characteristics and lifespan characteristics. However, Patent Documents 1 and 2 do not focus on the dispersibility of fibrous conductive additives in high-concentration compositions, and the improvement of battery performance due to the localization of fibrous conductive additives has not been investigated.

[0008] The present invention aims to provide an electrode composition that can improve battery characteristics while suppressing the localization of fibrous conductive additives within the active material layer, even when the solid content concentration is increased to more than 75% by mass. 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 an electrode sheet for an all-solid-state secondary battery and a method for manufacturing an all-solid-state secondary battery.

[0009] The present inventors have diligently pursued research on electrode compositions using a fibrous conductive additive instead of a particulate conductive agent as a material for forming the constituent layers of an all-solid-state secondary battery. Their objective was to achieve a composition in which the fibrous conductive additive is suitably dispersed (delocalization of the fibrous conductive additive is suppressed) by breaking down the entanglement of the fibrous conductive additive itself while suppressing the re-aggregation (re-entanglement) of the broken-down material (fibrous conductive additive in a broken-down state). As a result, they discovered that by using a linear polymer structure for the polymer used in combination with the fibrous conductive additive, and by combining the linear polymer, dispersion medium, and fibrous conductive additive in combinations that satisfy the conditions (1) to (4) described later, it is possible to highly disperse the fibrous conductive additive in addition to the inorganic solid electrolyte and active material, even when the solid content concentration is increased to over 75% by mass (condition (5)), far exceeding the 52% by mass described in Patent Document 2. Furthermore, we found that this high-concentration composition can suppress the re-aggregation, re-entanglement, and ultimately localization of the fibrous conductive additive even during the formation stage of the active material layer. As a result, it is possible to realize an all-solid-state secondary battery that exhibits excellent battery characteristics by taking advantage of the benefits of the fibrous conductive additive. This invention was completed after further investigation based on these findings.

[0010] In other words, the above problem was solved by the following means: <1> An electrode composition containing an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a positive electrode active material, a fibrous conductive additive, a linear polymer, and a dispersion medium, and satisfying the following conditions (1) to (5): (1) The linear polymer is dissolved in the dispersion medium; (2) The weight-average molecular weight of the linear polymer is 3.0 × 10 ３ (3) The average short axis diameter of the fibrous conductive additive is 1 to 300 nm, and the average long axis length is 500 nm to 50 μm. (4) The adsorption rate A of the linear polymer to the fibrous conductive additive in the dispersion medium. ＦＡ (5) The solid content in the electrode composition is greater than 4% and less than or equal to 45%. <2> Adsorption rate A ＦＡThe electrode composition according to <1>, wherein the amount is greater than 7% and less than or equal to 30%. <3> The electrode composition according to <1> or <2>, wherein the average short axis diameter of the fibrous conductive additive is 1 to 200 nm and the average long axis length is 500 nm to 10 μm. <4> The weight-average molecular weight of the linear polymer is 1.0 × 10 ４ ~7.0 x 10 ５ The electrode composition according to any one of <1> to <3>. <5> The electrode composition according to any one of <1> to <4>, wherein the solid content in the electrode composition is more than 80% by mass. <6> The electrode composition according to any one of <1> to <5>, wherein the linear polymer comprises a component having at least one functional group from the following functional group group (a). (Functional group group (a)) Sulfonic acid group, phosphoric acid group, phosphonic acid group, carboxyl group, hydroxyl group, oxetane group, epoxy group, carboxylic anhydride group, thiol group, ether group, thioether group, thioester group, thiocarbamate group, imino group, amide group, urethane group, urea group, thiourea group, heterocyclic group, aryl group, fluoroalkyl group, siloxane group, carbonate group, amino group, and salts thereof. <7> The electrode composition according to any one of <1> to <6>, wherein the linear polymer comprises a component having a substituent with 8 or more carbon atoms in its side chain. <8> An electrode composition according to any one of <1> to <7>, wherein the linear polymer comprises a (meth)acrylic polymer. <9> An electrode sheet for an all-solid-state secondary battery having a positive electrode active material layer made of the electrode composition according to any one of <1> to <8> above. <10> An all-solid-state secondary battery comprising a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order, wherein the upper positive electrode active material layer is a layer formed using the electrode composition according to any one of <1> to <8> above. <11> A method for manufacturing an electrode sheet for an all-solid-state secondary battery, comprising forming a film of the electrode composition according to any one of <1> to <8> above. <12> A method for manufacturing an all-solid-state secondary battery, comprising manufacturing an all-solid-state secondary battery via the manufacturing method described in <11> above.

[0011] The present invention provides an electrode composition that can improve battery characteristics while suppressing the localization of fibrous conductive additives within the active material layer, even when the solid content concentration is increased to over 75% by mass. Furthermore, the present invention provides 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 an electrode sheet for an all-solid-state secondary battery and a method for manufacturing an all-solid-state secondary battery. The above and other features and advantages of the present invention will become clearer from the following description with reference to the attached drawings as appropriate.

[0012] Figure 1 is a schematic longitudinal cross-sectional view showing an all-solid-state secondary battery according to a preferred embodiment of the present invention. Figure 2 is a schematic longitudinal cross-sectional view showing a coin-type all-solid-state secondary battery fabricated in the example.

[0013] In the present invention, when describing the content, physical properties, etc., of components by indicating numerical ranges, if the upper and lower limits of the numerical range are described separately, either upper or lower limit can be appropriately combined to form a specific numerical range. On the other hand, when multiple numerical ranges represented by "~" are set and described, the upper and lower limits that form the numerical range are not limited to the specific combination of upper and lower limits written before and after "~" as a specific numerical range, but can be a numerical range formed by appropriately combining the upper and lower limits of each numerical range. In the present invention, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits.

[0014] In this invention, the designation of a compound (for example, when referred to as a compound) includes not only the compound itself, but also its salts and ions. It also includes derivatives in which a part of the compound has been altered, such as by introducing substituents, to the extent that it does not impair the effects of this invention. In this invention, (meth)acrylic means either or both acrylic and methacrylic. The same applies to (meth)acrylate. In this invention, substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) that are not specified as substituted or unsubstituted mean that the group may have appropriate substituents. Therefore, in this invention, even when simply referred to as a YYY group, this YYY group includes not only the unsubstituted form but also the form with substituents. This is also true for compounds that are not specified as substituted or unsubstituted. A preferred substituent is, for example, substituent Z, which will be described later. In this invention, when there are multiple substituents, etc. indicated by a specific symbol, or when multiple substituents, etc. are specified simultaneously, it means that each substituent, etc. may be the same as or different from the others. Furthermore, even if not specifically stated otherwise, it means that when multiple substituents are adjacent to each other, they may be linked to each other or fused to form a ring.

[0015] In this invention, the polymer's main chain refers to a linear molecular chain in which all other molecular chains constituting the polymer can be considered as branched chains or pendant groups relative to the main chain. Depending on the weight-average molecular weight of the molecular chains considered as branched chains or pendant chains, typically the longest chain among the molecular chains constituting the polymer becomes the main chain. However, the end groups at the ends of the polymer are not included in the main chain. In contrast, the polymer's side chains refer to molecular chains other than the main chain, and include short molecular chains and long molecular chains (graft chains). Examples of end groups include hydrogen atoms, alkyl groups, aryl groups, hydroxyl groups, and residues such as polymerization initiators.

[0016] In the present invention, either the positive electrode active material layer or the negative electrode active material layer, or both together, may be simply referred to as the active material layer or electrode active material layer, and either the positive electrode active material or the negative electrode active material, or both together, may be simply referred to as the active material or electrode active material.

[0017] [Electrode Composition] This electrode composition contains an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a positive electrode active material, a fibrous conductive additive, a linear polymer, and a dispersion medium, and satisfies the conditions (1) to (5) described below. Even when the solid content concentration of this electrode composition is increased to more than 75% by mass, the fibrous conductive additive can be well dispersed in addition to the inorganic solid electrolyte and positive electrode active material. By using this electrode composition as an active material layer forming material, it is possible to form an active material layer that suppresses the re-aggregation and re-entanglement of the fibrous conductive additive (sometimes simply referred to as "re-aggregation"), preferably an active material layer that satisfies the physical properties described below, and an all-solid-state secondary battery with excellent battery performance, such as charge-discharge characteristics (discharge capacity characteristics) and life characteristics can be realized.

[0018] Although the details of the reason are not yet clear, as will be described later, it is thought that the combined effects of conditions (1) to (5) allow the linear polymer to specifically interact with, for example, adsorb to, a particular fibrous conductive additive, thereby exhibiting properties (adsorption state, adsorption force). This enhances the dispersibility of the fibrous conductive additive in the composition and maintains it even during the formation of the active material layer. As a result, the active material layer formed using the electrode composition of the present invention has a reduced amount of re-aggregated fibrous conductive additive (suppression of localization of the fibrous conductive additive by aggregates) and preferably has a flat surface. It is thought that an all-solid-state secondary battery having such an active material layer exhibits excellent battery characteristics, such as excellent charge-discharge characteristics and life characteristics, and preferably short-circuit suppression characteristics. This improvement in battery performance in the present invention is similarly exhibited even in high-temperature environments where battery performance tends to deteriorate significantly.

[0019] Furthermore, since the electrode composition of the present invention can increase the solid content concentration to more than 75% by mass, the drying time after coating of the electrode composition of the present invention can be shortened in the production of electrode sheets for all-solid-state secondary batteries, and it also has manufacturing advantages (manufacturability) such as reduced environmental impact due to reduced dispersant evaporation and reduced manufacturing costs.

[0020] In the electrode composition of the present invention, the linear polymer is thought to function as a dispersant that disperses solid particles such as the fibrous conductive additive in a dispersion medium by adsorbing at least to the fibrous conductive additive and, as appropriate, to the inorganic solid electrolyte and the positive electrode active material, and interposing between solid particles. Here, the adsorption of the linear polymer 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, in the active material layer, the linear polymer functions as a binder that binds solid particles together. It may also function as a binder that binds the current collector to the solid particles.

[0021] The electrode composition of the present invention is a positive electrode composition for all-solid-state secondary batteries (positive electrode active material layer formation) that includes a positive electrode active material. The positive electrode composition contains a fibrous conductive additive as a conductive additive, which has the advantage of achieving high electronic conductivity even with a smaller amount compared to a negative electrode composition containing a negative electrode active material. Furthermore, it has the advantage of achieving higher battery performance in high-temperature environments compared to a negative electrode composition.

[0022] As described above, the electrode composition of the present invention satisfies the following conditions (1) to (5). Each condition can also be described as a condition in which, in the presence of an inorganic solid electrolyte and a positive electrode active material, the linear polymer, the fibrous conductive additive, and the dispersion medium cooperate to disperse the fibrous conductive additive, preferably while suppressing aggregation. Each condition will be described below.

[0023] <Condition (1)> Linear polymer is dissolved in the dispersion medium. The linear polymer contained in the electrode composition of the present invention exhibits the property of dissolving in the dispersion medium contained in the electrode composition of the present invention (solubility). In the electrode composition, the linear polymer usually exists in a dissolved state in the dispersion medium, although this depends on the content of the dispersion medium. When condition (1) is combined with conditions (2) to (5) in the electrode composition containing the above components, the molecular chains (molecular structure) of the linear polymer are spread out in the dispersion medium and adsorbed appropriately to solid particles, especially fibrous conductive additives. This allows for good dispersion of the fibrous conductive additive by repelling solid particles, especially fibrous conductive additives, that are moderately adsorbed or nearby, and is also thought to effectively suppress re-aggregation and precipitation of the fibrous conductive additive during the formation stage of the active material layer. In the present invention, the solubility of the linear polymer in the dispersion medium can be appropriately imparted depending on the structure and composition (types and content of constituent components) of the linear polymer, the weight-average molecular weight of the linear polymer, and the combination with the dispersion medium.

[0024] In the present invention, "a linear polymer dissolved in the dispersion medium" means that the linear polymer is dissolved in the dispersion medium in the electrode composition, and is not limited to the embodiment in which all of the linear polymer is dissolved in the dispersion medium. For example, if the solubility in the dispersion medium is 80% or more, a portion of the linear polymer may be present in an insoluble state in the electrode composition. The method for measuring solubility is as follows. Specifically, a specified amount of the linear polymer 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 thereto, 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 mixture obtained after 24 hours of stirring is measured under the following conditions. This test (transmittance measurement) is performed by changing the amount of dissolved linear polymer (the specified amount above), and the upper limit concentration X (mass%) at which the transmittance is 99.8% is taken as the solubility of the linear polymer in the above dispersion medium. - Transmittance Measurement Conditions - Dynamic Light Scattering (DLS) Measurement Device: Otsuka Electronics DLS Measurement Device DLS-8000 Laser Wavelength, Output: 488 nm / 100 mW Sample Cell: NMR Tube

[0025] <Condition (2)> The weight average molecular weight of the linear polymer is 3.0×10 ３ or more. In the electrode composition containing the above components, when condition (2) is combined with the other four conditions, the molecular chains (molecular structures) of the linear polymer are greatly expanded in the dispersion medium, and it is considered that the aggregation and re-aggregation of solid particles, particularly fibrous conductive aids, can be more effectively suppressed and the dispersibility can be further enhanced. The weight average molecular weight of the linear polymer is 1.0×10 ４ or more, preferably 3.0×10 ４ or more, more preferably 5.0×10 ４ or more, and still more preferably 4.0×10 ６ or less, preferably 7.0×10 ５ or less, more preferably 5.0×10 ５ or less, still more preferably 4.0×10 ５ or less, and particularly preferably 4.0×10

[0026] - Measurement of Molecular Weight - In this invention, unless otherwise specified, the weight-average molecular weight of a polymer refers to the weight-average molecular weight on a standard polystyrene basis, measured by gel permeation chromatography (GPC). The measurement method basically involves setting the following conditions M1 or M2 (preferred). However, depending on the type of polymer, an appropriate eluent may be selected and used as appropriate. (Condition M1) Column: Two TOSOH TSKgel Super AWM-H (product name, manufactured by Tosoh Corporation) connected together. Carrier: 10 mM LiBr / N-methylpyrrolidone. Measurement temperature: 40°C. Carrier flow rate: 1.0 ml / min. Sample concentration: 0.1% by mass. Detector: RI (refractive index) detector. (Condition M2) Column: A column made by connecting TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, or TOSOH TSKgel Super HZ2000 (all product names, manufactured by Tosoh Corporation). Carrier: Tetrahydrofuran. Measurement temperature: 40°C. Carrier flow rate: 1.0 ml / min. Sample concentration: 0.1% by mass. Detector: RI (refractive index) detector.

[0027] <Condition (3)> The average short axis diameter of the fibrous conductive additive is 1 to 300 nm, and the average long axis length of the fibrous conductive additive is 500 nm to 50 μm. When condition (3) is combined with the other four conditions in an electrode composition containing the above components, it is thought that the linear polymer and the fibrous conductive additive exhibit a specific interaction, particularly an adsorption state, in the dispersion medium, thereby more effectively suppressing aggregation and re-aggregation of the fibrous conductive additive. The average short axis diameter (average diameter) of the fibrous conductive additive is preferably small in terms of the electrical conductivity of the active material layer (construction of electron conduction paths), more preferably 1 to 250 nm, even more preferably 1 to 200 nm, and particularly preferably 1 to 50 nm, in order to further improve the dispersibility of the fibrous conductive additive and further improve the battery characteristics of the all-solid-state secondary battery. On the other hand, the average major axis length (average length) of the fibrous conductive additive is preferably 500 nm to 50 μm, more preferably 500 nm to 20 μm, even more preferably 500 nm to 10 μm, particularly preferably 750 nm to 10 μm, and most preferably 1 to 10 μm, in order to further improve the dispersibility of the fibrous conductive additive and further improve the battery characteristics of the all-solid-state secondary battery. In the present invention, the average minor axis diameter and average major axis length of the fibrous conductive additive are values ​​measured by the method described in the examples below. The average minor axis diameter and average major axis length of the fibrous conductive additive can be adjusted as appropriate by crushing, classification, etc.

[0028] <Condition (4)> Adsorption rate A of linear polymer to fibrous conductive additive in dispersion medium ＦＡ The adsorption rate A is greater than 4% and less than or equal to 45%. In an electrode composition containing the above components, when condition (4) is combined with the other four conditions, the linear polymer in the dispersion medium exhibits a specific interaction with the fibrous conductive additive, particularly an adsorption state, to an appropriate extent, thereby more effectively suppressing aggregation and re-aggregation of the fibrous conductive additive, and enabling the construction of sufficient conduction paths (electron conduction paths, ion conduction paths), particularly electron conduction paths containing the fibrous conductive additive. ＦＡIn order to achieve further improvement in the dispersibility of the fibrous conductive additive and further improvement in the battery characteristics of the all-solid-state secondary battery, it is preferable that the adsorption rate A is greater than 7% and 40%, more preferably greater than 7% and 30%, even more preferably greater than 9% and 30%, and particularly preferably greater than 12% and 21%. In the present invention, the adsorption rate A for the fibrous conductive additive is ＦＡ This can be appropriately set depending on the type of linear polymer (structure and composition of the polymer chain), the weight-average molecular weight of the linear polymer, the type or content of functional groups selected from the functional group group (a) described later, the surface state of the fibrous conductive additive, etc.

[0029] Adsorption rate A ＦＡ This value is measured using a fibrous conductive additive, a linear polymer, and a dispersion medium contained in the electrode composition, and is an index indicating the degree to which the linear polymer interacts with, and particularly adsorbs, the fibrous conductive additive in the dispersion medium. Here, the adsorption of the linear polymer to the fibrous conductive additive is not particularly limited, but 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 fibrous conductive additives, the adsorption rate is taken for fibrous conductive additives having the same composition as the fibrous conductive additives (type and content) in the electrode composition. Similarly, if the electrode composition contains multiple types of dispersion mediums, the adsorption rate is taken for dispersion mediums having the same composition as the dispersion mediums (type and content) in the electrode composition. Similarly, if the electrode composition contains multiple types of linear polymers, the adsorption rate is taken for multiple types of linear polymers. Adsorption Rate A ＦＡ The (%) value shall be the value measured by the method described in the examples below.

[0030] The electrode composition of the present invention is a high-concentration slurry in which an inorganic solid electrolyte, a positive electrode active material, a fibrous conductive additive, and a linear polymer are dispersed in a dispersion medium. That is, the electrode composition of the present invention satisfies the following condition (5). <Condition (5)> The solid content (at 25°C) in the electrode composition is greater than 75% by mass and less than or equal to 95% by mass. In an electrode composition containing the above components, the dispersibility of the fibrous conductive additive can be improved in the electrode composition by combining each component and satisfying conditions (1) to (4), thereby improving the battery characteristics of the all-solid-state secondary battery. In particular, even when the solid content (solid content concentration) is increased to a high concentration of 75% by mass, the dispersibility of the fibrous conductive additive and the battery characteristics of the all-solid-state secondary battery can be maintained. The solid content in the electrode composition is preferably greater than 77% by mass, more preferably greater than 79% by mass, and even more preferably greater than 80% by mass at 25°C, in terms of maintaining or improving the dispersibility of the fibrous conductive additive and the battery characteristics of the all-solid-state secondary battery. The upper limit of the solid content is practically 95% by mass, but it is preferable to set it to 90% by mass or less, preferably 88% by mass or less, and preferably 86% by mass or less, in order to maintain the dispersibility of the fibrous conductive additive and the battery characteristics of the all-solid-state secondary battery. In the present invention, solid content (solid components) refers to components that do not volatilize or evaporate when the electrode composition is dried under a pressure of 1 mmHg and a nitrogen atmosphere at 150°C for 6 hours. Typically, it refers to components other than the dispersion medium described later.

[0031] The electrode composition of the present invention is preferably a non-aqueous composition. In the present invention, a non-aqueous composition includes not only a form that does not contain water, but also a form in which the water content (also called water content) is preferably 500 ppm or less. In a non-aqueous composition, the water content is more preferably 200 ppm or less, even more preferably 100 ppm or less, and particularly preferably 50 ppm or less. When the electrode composition is a non-aqueous composition, the deterioration of the inorganic solid electrolyte can be suppressed. The water content indicates the amount of water contained in the electrode composition (mass ratio to the electrode composition), and specifically, it is the value measured by filtering with a 0.02 μm membrane filter and using Karl Fischer titration.

[0032] The electrode composition of the present invention can be preferably used as an electrode sheet for all-solid-state secondary batteries and as a material for forming the positive electrode active material layer of an all-solid-state secondary battery.

[0033] The following describes the components contained in and potentially contained in the electrode composition of the present invention.

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

[0035] The inorganic solid electrolyte described above can be appropriately selected from solid 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 and effectively suppressing the increase in interfacial resistance, sulfide-based inorganic solid electrolytes are preferred. When the all-solid-state secondary battery of the present invention is a lithium-ion battery, the inorganic solid electrolyte preferably has lithium ion conductivity.

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

[0037] Examples of sulfide-based inorganic solid electrolytes include lithium-ion conductive inorganic solid electrolytes that satisfy the composition shown in the following formula (S1). ａ１ M ｂ１ P ｃ１ S ｄ１ A ｅ１ (S1) In formula (S1), L represents an element selected from Li, Na, and K, with Li being preferred. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. A represents an element selected from I, Br, Cl, and F. a1 to e1 represent the composition ratio of each element, where a1:b1:c1:d1:e1 satisfies 1 to 12:0 to 5:1:2 to 12:0 to 10. a1 is preferably 1 to 9, more preferably 1.5 to 7.5. b1 is preferably 0 to 3, more preferably 0 to 1. d1 is preferably 2.5 to 10, more preferably 3.0 to 8.5. e1 is preferably 0 to 5, more preferably 0 to 3.

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

[0039] The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystalline (glass-ceramic), or partially crystalline. For example, Li-P-S glass containing Li, P, and S, or Li-P-S glass-ceramic containing Li, P, and S can be used. The sulfide-based inorganic solid electrolyte is, for example, lithium sulfide (Li ２ S), phosphorus sulfide (for example, diphosphorus pentasulfide (P ２ S ５)), elemental phosphorus, elemental sulfur, sodium sulfide, hydrogen sulfide, lithium halides (e.g., LiI, LiBr, LiCl) and sulfides of the element represented by M above (e.g., SiS ２ SnS, GeS ２ It can be produced by the reaction of at least two or more raw materials in ).

[0040] In Li-P-S glass and Li-P-S glass ceramics, Li ２ S and P ２ S ５ The ratio to Li ２ S:P ２ S ５ The molar ratio is preferably 60:40 to 90:10, more preferably 68:32 to 78:22. Li ２ S and P ２ S ５ By setting the ratio within this range, the lithium ion conductivity can be increased. Specifically, the lithium ion conductivity is preferably set to 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 ratio to be less than or equal to S / cm.

[0041] As a specific example of a sulfide-based inorganic solid electrolyte, an example of raw material combinations is shown below. For example, Li ２ S-P ２ S ５ Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ -H ２ S, Li ２ S-P ２ S ５ -H ２ S-LiCl, Li ２ S-LiI-P ２ S ５ Li ２ S-LiI-Li ２ O-P ２ S ５ Li ２ S-LiBr-P２ S ５ 、Li ２ S-Li ２ O-P ２ S ５ 、Li ２ S-Li ３ PO ４ -P ２ S ５ 、Li ２ S-P ２ S ５ -P ２ O ５ 、Li ２ S-P ２ S ５ -SiS ２ 、Li ２ S-P ２ S ５ -SiS ２ -LiCl、Li ２ S-P ２ S ５ -SnS、Li ２ S-P ２ S ５ -Al ２ S ３ 、Li ２ S-GeS ２ 、Li ２ S-GeS ２ -ZnS、Li ２ S-Ga ２ S ３ 、Li ２ S-GeS ２ -Ga ２ S ３ 、Li ２ S-GeS ２ -P ２ S ５ 、Li ２ S-GeS ２ -Sb ２ S ５ 、Li ２ S-GeS ２ -Al ２ S ３ 、Li ２ S-SiS ２ 、Li ２ S-Al ２ S ３ 、Li ２ S-SiS ２ -Al ２S ３ Li ２ S-SiS ２ -P ２ S ５ Li ２ S-SiS ２ -P ２ S ５ -LiI, Li ２ S-SiS ２ -LiI, Li ２ S-SiS ２ -Li ４ SiO ４ Li ２ S-SiS ２ -Li ３ PO ４ Li １０ GeP ２ S １２ These are some examples. However, the mixing ratio of each raw material is not specified. As a method for synthesizing sulfide-based inorganic solid 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.

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

[0043] Specific examples of compounds include, for example, Li ｘａ La ｙａ TiO ３ [xa satisfies 0.3 ≤ xa ≤ 0.7, and ya satisfies 0.3 ≤ ya ≤ 0.7.] (LLT); Li ｘｂ La ｙｂ Zr ｚｂ Mｂｂ ｍｂ O ｎｂ (M ｂｂ is one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn. xb satisfies 5 ≤ ​​xb ≤ 10, yb satisfies 1 ≤ yb ≤ 4, zb satisfies 1 ≤ zb ≤ 4, mb satisfies 0 ≤ mb ≤ 2, and nb satisfies 5 ≤ ​​nb ≤ 20. ); Li ｘｃ B ｙｃ M ｃｃ ｚｃ O ｎｃ (M ｃｃ is one or more elements selected from C, S, Al, Si, Ga, Ge, In, and Sn. xc satisfies 0 < xc ≤ 5, yc satisfies 0 < yc ≤ 1, zc satisfies 0 < zc ≤ 1, and nc satisfies 0 < nc ≤ 6. ); Li ｘｄ (Al, Ga) ｙｄ (Ti, Ge) ｚｄ Si ａｄ P ｍｄ O ｎｄ (xd satisfies 1 ≤ xd ≤ 3, yd satisfies 0 ≤ yd ≤ 1, zd satisfies 0 ≤ zd ≤ 2, ad satisfies 0 ≤ ad ≤ 1, md satisfies 1 ≤ md ≤ 7, and nd satisfies 3 ≤ nd ≤ 13.) ; Li （３－２ｘｅ） M ｅｅ ｘｅ D ｅｅ O(xe represents a number between 0 and 0.1, M ｅｅ D represents a divalent metal atom. ｅｅ represents a halogen atom or a combination of two or more halogen atoms. ); Li ｘｆ Si ｙｆ O ｚｆ (xf satisfies 1 ≤ xf ≤ 5, yf satisfies 0 < yf ≤ 3, and zf satisfies 1 ≤ zf ≤ 10.) ; Li ｘｇ S ｙｇ O ｚｇ (xg satisfies 1 ≤ xg ≤ 3, yg satisfies 0 < yg ≤ 2, and zg satisfies 1 ≤ zg ≤ 10.) ; Li ３ BO ３ Li ３ BO ３ -Li ２ SO ４ Li ２ O-B２ O ３ -P ２ O ５ Li ２ O-SiO ２ Li ６ BaLa ２ Ta ２ O １２ Li ３ PO （４－３／２ｗ） N ｗ (where w < 1); Li having a LISICON (Lithium super ionic conductor) type crystal structure ３．５ Zn ０．２５ GeO ４ La having a perovskite crystal structure ０．５５ Li ０．３５ TiO ３ LiTi having a NASICON (Natrium super ionic conductor) type crystal structure ２ P ３ O １２ Li １＋ｘｈ＋ｙｈ (Al, Ga) ｘｈ (Ti, Ge) ２－ｘｈ Si ｙｈ P ３－ｙｈ O １２ (xh satisfies 0 ≤ xh ≤ 1, and yh satisfies 0 ≤ yh ≤ 1.) Li having a garnet-type crystal structure ７ La ３ Zr ２ O １２ Examples include (LLZ). Phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li ３ PO ４ LiPON; LiPOD １ (D １ The element is preferably one or more elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au. Other examples include LiA. １ ON (A １ (This is one or more elements selected from Si, B, Ge, Al, C, and Ga.) Other elements such as () can also be preferably used.

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

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

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

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

[0048] The electrode composition may contain one or more types of inorganic solid electrolytes. The amount of inorganic solid electrolyte in the electrode composition is not particularly limited and can be determined as appropriate. In terms of dispersibility and battery characteristics, the total amount of the inorganic solid electrolyte and positive electrode active material 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.

[0049] The content of inorganic solid electrolyte alone in the electrode composition is appropriately determined considering the total content with the positive electrode active material. For example, it is preferably 5 to 70% by mass, more preferably 10 to 50% by mass, and even more preferably 10 to 30% by mass, based on 100% by mass of solid content. The ratio of the content of inorganic solid electrolyte to the content of the positive electrode active material [content of inorganic solid electrolyte: content of positive electrode active material] in 100% by mass of solid content of the electrode composition is not particularly limited, but for example, it is preferably 1:1 to 1:6, and more preferably 1:1.2 to 1:5. When the electrode composition contains two or more types of inorganic solid electrolytes, the content of inorganic solid electrolytes is the total content.

[0050] <Positive Electrode Active Material> The electrode composition of the present invention contains a positive electrode active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the periodic table. The positive electrode active material is an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the periodic table, and is preferably capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above characteristics, and may be a transition metal oxide, an organic substance, or an element that can be compounded with Li such as sulfur.

[0051] In particular, a transition metal oxide is preferred as the positive electrode active material, and the transition metal element M ａ A transition metal oxide having one or more elements selected from Co, Ni, Fe, Mn, Cu, and V is more preferable. ｂOther elements of the periodic table of metals, such as elements from Group 1 (Ia), Group 2 (IIa), Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B, may be mixed. The amount of the transition metal element M may be used. ａ Li / M ａ A more preferable product is one synthesized by mixing the elements so that the molar ratio is 0.3 to 2.2. Specific examples of transition metal oxides include (MA) transition metal oxides having a layered rock salt structure, (MB) transition metal oxides having a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD) lithium-containing transition metal halogenated phosphate compounds, and (ME) lithium-containing transition metal silicate compounds.

[0052] (MA) As a specific example of a transition metal oxide having a layered rock salt structure, LiCoO ２ (Lithium cobalt oxide [LCO]), LiNi ２ O ２ (Lithium nickelate), LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ (Lithium nickel-cobalt aluminate [NCA]), LiNi １／３ Co １／３ Mn １／３ O ２ (Also known as lithium nickel manganese cobalt oxide [NMC], [NCM]) and LiNi ０．５ Mn ０．５ O ２ (Lithium manganese nickelate) is one example. (MB) LiMn is a specific example of a transition metal oxide having a spinel-type structure. ２ O ４ (LMO), LiCoMnO ４ Li ２ FeMn ３ O ８ Li ２ CuMn ３ O ８ Li ２ CrMn ３ O ８ and Li ２ NiMn ３ O ８Examples include (MC) lithium-containing transition metal phosphate compounds, such as LiFePO ４ and Li ３ Fe ２ (PO ４ ) ３ Olivine-type iron phosphates such as LiFeP ２ O ７ Iron pyrophosphates such as LiCoPO ４ Cobalt phosphates such as Li ３ V ２ (PO ４ ) ３ Examples include monoclinic vanadium phosphate salts such as (lithium vanadium phosphate). Examples of (MD) lithium-containing transition metal halide phosphate compounds include Li ２ FePO ４ F, etc., iron fluoride phosphate, Li ２ MnPO ４ F and other manganese fluoride phosphate salts and Li ２ CoPO ４ Examples include cobalt fluoride phosphates such as F. (ME) Examples of lithium-containing transition metal silicate compounds include Li ２ FeSiO ４ Li ２ MnSiO ４ Li ２ CoSiO ４ Examples include the above. In the present invention, transition metal oxides having a (MA) layered rock salt type structure are preferred, and LCO or NMC are more preferred.

[0053] The surface of the positive 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. Examples include spinel titanate, tantalum oxides, niobium oxides, lithium niobate compounds, and specifically Li ４ Ti ５ O １２ Li ２ Ti ２ O ５ , LiTaO ３ LiNbo ３ LiAlO ２ Li ２ZrO ３ Li ２ WO ４ Li ２ TiO ３ Li ２ B ４ O ７ Li ３ PO ４ Li ２ MoO ４ Li ３ BO ３ LiBO ２ Li ２ CO ３ Li ２ SiO ３ SiO ２ , TiO ２ , ZrO ２ Al ２ O ３ , B ２ O ３ These are some examples. Furthermore, the electrode surface containing the positive electrode active material may be surface-treated with sulfur or phosphorus. In addition, the particle surface of the positive electrode active material may be surface-treated with active light or an active gas (such as plasma) before or after the above surface coating.

[0054] 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.

[0055] 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 adjusted 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.

[0056] 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 solid content, 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. When the electrode composition contains two or more positive electrode active materials, the content of the positive electrode active materials is the total content.

[0057] <Fibrous Conductive Additive> The electrode composition of the present invention contains a fibrous conductive additive. The fibrous conductive additive is not particularly limited as long as it is fibrous having a specific average short axis diameter and average long axis length and functions as a conductive additive. In the present invention, a conductive additive refers to a material that 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, materials that 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 material functions as an active material when the battery is charged and discharged is not unique, but is determined by its combination with the active material.

[0058] The average minor axis diameter and average major axis length of the fibrous conductive additive are as described above. In the fibrous conductive additive, the ratio of the average major axis length to the average minor axis diameter [average major axis length / average minor axis diameter] is not particularly limited and can be determined as appropriate. In the present invention, the ratio [average major axis length / average minor axis diameter] is preferably 10 or more, and is 10 to 2.0 × 10, in that aggregation and re-aggregation of the fibrous conductive additive is more effectively suppressed. ４ It is more preferable that it be 20 to 1.0 × 10 ４ It is even more preferable that the values ​​be 25 to 2.0 × 10 ３ It is even more preferable that this is the case. In the present invention, the ratio [average major axis length / average minor axis diameter] can be determined from the average minor axis diameter and average major axis length of the fibrous conductive additive measured by the method described in the examples below.

[0059] The materials used to form the fibrous conductive additive are not particularly limited and include carbon materials such as vapor-grown carbon fibers or carbon nanotubes, metallic materials such as copper and nickel, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives. As for the fibrous conductive additive, fibers formed from carbon materials (carbon fibers) are preferred, and carbon nanotubes are more preferred, due to their excellent effect in suppressing aggregation and re-aggregation.

[0060] Carbon nanotubes (CNTs) are coaxial tube-like structures formed by winding a planar carbon film (graphene sheet) into single-layer or multi-layer structures, and are characterized by their high electrical conductivity. Examples of carbon nanotubes include single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Multi-walled carbon nanotubes contain vapor-grown carbon fibers, and those with a two-layer structure are specifically called double-walled carbon nanotubes (DWCNTs). Carbon nanotubes can be commercially available or synthesized as appropriate. For example, commercially available single-walled carbon nanotubes include TUBALL (trade name, manufactured by OCSiAl) and ZEONANO SG101 (trade name, manufactured by Nippon Zeon Co., Ltd.), while commercially available multi-walled carbon nanotubes include VGCF-H (trade name, manufactured by Resonac) and Genotube 10B (trade name, manufactured by JEIO). Carbon nanotubes can be synthesized using various synthesis methods, such as arc discharge, laser evaporation, and chemical vapor deposition, utilizing hydrocarbon gases, for example.

[0061] The electrode composition of the present invention may contain one or more types of fibrous conductive additives. The content of the fibrous conductive additives in the electrode composition is not particularly limited and can be determined as appropriate. For example, with respect to 100% of the solid content, 0.01 to 20% by mass is preferred, 0.05 to 10% by mass is more preferred, and 0.05 to 5% by mass is even more preferred.

[0062] <Linear Polymers> The electrode composition of the present invention contains linear polymers. In the present invention, linear polymers refer to so-called linear polymers, which are unbranched polymers having unbranched polymerization chains (main chains). Here, branched polymers include graft polymers, star polymers, dendritic polymers (dendrimers), comb polymers, etc. Linear polymers can be defined as polymers obtained by polymerizing or condensing non-polymerizable monomers that do not have polymerization chains, in particular non-polymerizable monomers that do not have polymerization chains in the substructure that becomes the side chain of the polymer when incorporated into the polymer. Linear polymers can also be defined as polymers obtained by polymerizing or condensing monomers that have a molecular weight of 800 or less and are not macromonomers (monomers that, in principle, do not have a molecular weight distribution). In the present invention, the linear polymer may contain monomers having polymerization chains or macromonomers with a molecular weight of more than 800 as monomer components, as long as they amount to 2% by mass or less of the linear polymer by mass.

[0063] The aforementioned polymerization chain refers to a molecular chain in which two or more repeating units derived from one or more compounds are bonded together. Examples include the polymerization chains of sequential polymerization polymers or chain polymerization polymers described later.

[0064] As a linear polymer, it is preferable that it be a non-crosslinked polymer that does not have intentional crosslinking, in terms of solubility and dispersibility in the dispersion medium. In the present invention, "intentional crosslinking" means crosslinking that is actively performed (introduced) for the purpose of improving the physical properties of the polymer, and does not include unavoidable crosslinking during synthesis or use.

[0065] Preferred linear polymers include, for example, polymers having a polymer chain of at least one bond selected from urethane bonds, urea bonds, amide bonds, imide bonds, ester bonds, or siloxane bonds, or a polymer chain of carbon-carbon double bonds as its main chain. In the present invention, a polymer chain of carbon-carbon double bonds refers to a polymer chain formed by the polymerization of carbon-carbon double bonds (ethylenically unsaturated groups), and more specifically, refers to a polymer chain obtained by polymerization (homopolymerization or copolymerization) of monomers having carbon-carbon unsaturated bonds. More specifically, polymers having urethane bonds, urea bonds, amide bonds, imide bonds, ester bonds, or siloxane bonds as their main chain include, for example, sequential polymers (polycondensation, polyaddition, or addition condensation) such as polyurethane, polyurea, polyamide, polyimide, polyester, polyether, polycarbonate, and polysiloxane. Furthermore, polymers having a carbon-carbon double bond polymerization chain as the main chain include, for example, chain polymerization polymers such as fluoropolymers (fluorine-containing polymers), hydrocarbon polymers, vinyl polymers, and (meth)acrylic polymers. The polymerization mode of these polymers is not particularly limited and may be block copolymers, alternating copolymers, or random copolymers. Among these, chain polymerization polymers are preferred, hydrocarbon polymers, vinyl polymers, and (meth)acrylic polymers are more preferred, and (meth)acrylic polymers are even more preferred.

[0066] (Component C1 having at least one functional group from functional group (a)) The linear polymer preferably contains one or more components C1 having at least one functional group selected from functional group (a) described later. This component C1 improves the adsorption capacity of the linear polymer to the fibrous conductive additive, and further to the inorganic solid electrolyte and / or positive electrode active material, thereby contributing to improved dispersibility and adhesion. This component C1 may be any component forming the linear polymer. The functional group selected from functional group (a) (sometimes referred to as "functional group (a)") may be incorporated into the main chain of the linear polymer or into the side chain. When incorporated into the side chain, the functional group (a) may be directly bonded to the main chain, or to a linking group L Ｃ１They may be bonded via L. This component C1 is directly incorporated into the substructure of the linear polymer's main chain or linked to L. Ｃ１ It is preferable that the functional group (a) is located via the linking group L. The substructure incorporated into the main chain of the linear polymer is appropriately selected depending on the type of linear polymer, etc. For example, if the linear polymer is a chain polymer, a carbon chain (carbon-carbon bond) can be cited. Ｃ１ There are no particular restrictions on this, and the linking group L described later is not limited to this. Ｃ２ Examples include the linking group L. Ｃ１ is a -CO-O- group or -CO-N(R) Ｎ )-group (R Ｎ As described above, it is a group formed by combining () and an alkylene group.

[0067] The method for incorporating functional group (a) into the polymer chain will be described later.

[0068] <Functional Groups (a)> Sulfonic acid group (sulfo group), phosphate group, phosphonic acid group, carboxyl group, hydroxyl group, oxetane group, epoxy group, carboxylic anhydride group, thiol group (sulfanyl group), ether group (-O-), thioether group (-S-), thioester group (-CS-O-, -CO-S-, -CS-S-), thiocarbamate group (-NR-CS-O-, -NRS-CO-S-), imino group (=NR, -NR-), amide group (-CO-NR-), urethane group (-NR-CO-O-), urea group (-NR-CO-NR-), thiourea group (-NR-CS-NR-), heterocyclic group, aryl group, fluoroalkyl group, siloxane group, carbonate group (-O-CO-O-), amino group, and salts thereof

[0069] The chemical formulas enclosed in parentheses after each group name, such as an ether group, indicate the chemical structure of that group (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 hydrogen atoms being preferred. The substituent is not particularly limited and can be selected from substituent Z described later, with alkyl groups being preferred. In the present invention, if either R or the terminal group takes a hydrogen atom, this hydrogen atom is interpreted as R. Note that ether groups are included in carboxyl groups, hydroxyl groups, etc., but the -O- contained in these is not interpreted as an ether group. Similarly, thioether groups are included in thioester groups, etc., but the -S- contained in these is not interpreted as a thioether group. It is preferable that ether groups, thioether groups, imino groups, etc. are not included as bonds constituting a substructure incorporated into the main chain of a linear polymer, and it is preferable that they are incorporated into a substructure corresponding to the side chain of the linear polymer. Furthermore, it is preferable that hydroxyl groups, thiol groups, amino groups, etc., are not bonded (as terminal groups) to the substructures incorporated into the main chain of the linear polymer, but are bonded (as terminal groups) to the substructures corresponding to the side chains of the linear polymer.

[0070] The sulfo group, phosphoryl group, phosphonic acid group, heterocyclic group, amino 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 group, thioether group, thioester group, thiocarbamate group, imino group (-NR-), amide group, urethane group, urea group, thiourea group, etc. are included in the ring structure, it is classified as a heterocyclic group.

[0071] The carboxylic acid anhydride group is not particularly limited, but includes groups obtained by removing one or more hydrogen atoms from a carboxylic acid anhydride (for example, a group represented by formula (2a) below), the constituent components themselves obtained by copolymerizing polymerizable carboxylic acid anhydrides as copolymerizable compounds (for example, a constituent component represented by formula (2b) below), and further, groups obtained by cleaving the anhydride group when a carboxylic acid anhydride reacts with an active hydrogen compound. As for groups obtained by removing one or more hydrogen atoms from a carboxylic acid anhydride, groups obtained by removing one or more hydrogen atoms from a cyclic carboxylic acid anhydride or a cyclic carboxylic acid anhydride are preferred. Carboxylic acid anhydride groups derived from cyclic carboxylic acid anhydrides also correspond to heterocyclic groups, but in this invention they are classified as carboxylic acid anhydrides. Examples include cyclic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and benzoic anhydride, and cyclic carboxylic acid anhydrides such as maleic anhydride, phthalic anhydride, fumaric anhydride, succinic anhydride, and itaconic anhydride. The polymerizable carboxylic acid anhydride is not particularly limited, but includes carboxylic acid anhydrides having an unsaturated bond in the molecule, and polymerizable cyclic carboxylic acid anhydride is preferred. Specifically, examples include maleic anhydride and itaconic anhydride. Examples of carboxylic acid anhydrides 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 the bond position. The active hydrogen compound is not particularly limited as long as it is a compound that reacts with the carboxylic acid anhydride group, and examples include alcohol compounds, amine compounds, thiol compounds, etc.

[0072]

[0073] A fluoroalkyl group is a group in which at least one hydrogen atom of an alkyl group or cycloalkyl group is replaced with a fluorine atom, and the number of carbon atoms is preferably 1 to 20, more preferably 1 to 12, and even more preferably 1 to 6. The number of fluorine atoms on the carbon atoms may be such that some of the hydrogen atoms are replaced, or all of them are replaced (perfluoroalkyl group).

[0074] The siloxane group is not particularly limited, for example, -(SiR ２ -O) ｎｓ - or -Si- (O-SiR) ３A group having the structure represented by is preferred. R is as described above. The number of repetitions ns is preferably an integer from 1 to 100, more preferably an integer from 5 to 50, and even more preferably an integer from 10 to 30. -(SiR ２ -O) ｎｓ The terminal group of the - is as described above, and there is also -Si-(O-SiR) ３ You can also take it.

[0075] Groups that can form salts, such as hydroxyl groups, amino groups, carboxyl groups, sulfo groups, phosphate groups, phosphonic acid groups, and sulfanyl groups, may form salts. Examples of salts include various metal salts, ammonium salts, or amine salts.

[0076] The functional group (a) of component C1 is particularly preferably a hydroxyl group, carboxyl group, amide group, carboxylic anhydride group or its addition reaction group (e.g., monoalkyl maleate), aryl group, or salts thereof, in terms of adsorption (adhesion) to solid particles and further dispersibility.

[0077] A single component C1 may have one or more functional groups (a), and if it has two or more, they may or may not be bonded to each other.

[0078] The compound that leads to component C1 (also called a polymerizable compound having functional group (a)) is not particularly limited, but examples include compounds having at least one carbon-carbon unsaturated bond and at least one functional group (a). For example, a compound in which a carbon-carbon unsaturated bond and functional group (a) are directly bonded, or a compound in which a carbon-carbon unsaturated bond and functional group (a) are linked by a linking group L Ｃ１ This includes compounds bonded via a link, and further, compounds in which the functional group itself contains a carbon-carbon unsaturated bond (for example, the polymerizable carboxylic acid anhydride mentioned above). In addition, compounds having functional group (a) include compounds in which a functional group can be introduced into polymer components after polymerization by various reactions (for example, alcohol, amino, mercapto, or epoxy compounds (including polymers) that can undergo addition reactions or condensation reactions with components derived from carboxylic anhydride, components having carbon-carbon unsaturated bonds, etc.).

[0079] Polymerizable compounds are not particularly limited as long as they have a functional group (a), and include raw material compounds that constitute linear polymers, or compounds in which a functional group (a) has been introduced into these raw material compounds. For example, examples include (meth)acrylic compounds (M1) or other polymerizable compounds (M2) described later, or compounds in which a functional group (a) has been introduced into these, and further, compounds in which a functional group (a) has been introduced into any of the components represented by formulas (b-1) to (b-3) described later, or components represented by formula (1-1) described later. Specifically, polymerizable compounds having a functional group (a) include vinyl aromatic compounds (preferably styrene compounds), polymerizable carboxylic acid anhydrides, fluorinated vinyl compounds (preferably hexafluoropropene), and compounds in which a functional group (a) has been introduced into (meth)acrylic acid short-chain alkyl ester compounds (short-chain alkyl means alkyl group with 3 or fewer carbon atoms). As for compounds in which a functional group (a) has been introduced into polymerizable carboxylic acid anhydrides, as described above, for example, dicarboxylic acid monoester compounds obtained by addition reaction (ring-opening reaction) of maleic anhydride compounds with alcohols, etc. Compounds that yield component C1 having an amide group include, in addition to the (meth)acrylamide compounds described later, vinyl compounds containing an amide group, (meth)acrylate compounds containing an amide group, and (meth)acrylamide compounds containing an amide group. It is preferable that component C1 does not have a polymerization chain.

[0080] Substructures and linking groups L incorporated into the main chain Ｃ１ Each of these may have substituents other than the functional group (a). Such substituents are not particularly limited and include, for example, groups selected from substituent Z described later.

[0081] Specific examples of component C1 include those found in the specific examples of linear polymers shown later, but the present invention is not limited to these.

[0082] The content of component C1 in the linear polymer is not particularly limited and is selected from the range of 0 to 100% by mass. The above content of component C1 is preferably 0.01 to 70% by mass, more preferably 0.01 to 50% by mass, and even more preferably 0.01 to 30% by mass, in terms of the dispersibility and binding properties of the linear polymer. The lower limit can be, for example, 0.3% by mass or more, or 1.5% by mass or more.

[0083] When the linear polymer is a (meth)acrylic polymer, the content of component C1 in the linear polymer can be as described above, but it is also preferable to set it to, for example, 0.1 to 10% by mass, and most preferably to 0.3 to 8% by mass.

[0084] When the linear polymer is a hydrocarbon polymer, the content of component C1 in the linear polymer can be as described above, but it is also preferable to set it to, for example, 20 to 85% by mass, and most preferably 40 to 80% by mass. However, regardless of the above range, the content of components other than those derived from styrene compounds in component C1 is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more. As an upper limit, it is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less of the total components constituting the hydrocarbon polymer.

[0085] When the linear polymer is a vinyl polymer, the content of component C1 in the linear polymer can be as described above, but it is also preferable to set it to, for example, 5 to 80% by mass, and most preferably 15 to 70% by mass. When the linear polymer is a fluoropolymer, the content of component C1 in the linear polymer can be as described above, but it is also preferable to set it to, for example, 20 to 90% by mass, and more preferably 50 to 75% by mass or 20 to 50% by mass. When the linear polymer has multiple components C1, the content of component C1 is the total amount. Furthermore, when a single component has multiple or multiple types of functional groups, the content of component C1 usually refers to the content of this component C1.

[0086] (Component C2 having substituents with 8 or more carbon atoms as side chains) The linear polymer preferably contains one or more components C2 having substituents with 8 or more carbon atoms as side chains. This component C2 contributes to improved dispersibility by reducing the polarity of the linear polymer and increasing its solubility in the dispersion medium. Note that if component C2 has the above functional group (a), it will be referred to as component C1 instead of component C2. This component C2 may be any of the components forming the linear polymer, and its substituents with 8 or more carbon atoms are introduced as a side chain of the linear polymer or as part thereof. This component C2 is directly incorporated into the substructure incorporated into the main chain of the linear polymer or into a linking group L Ｃ２ It is preferable that the substituent has 8 or more carbon atoms via a nucleotide.

[0087] The substructure incorporated into the main chain of the linear polymer is appropriately selected depending on the type of linear polymer, etc. For example, if the linear polymer is a chain polymer, a carbon chain (carbon-carbon bond) can be used. The substituents having 8 or more carbon atoms are not particularly limited, and for example, the substituent Z described later, which has 8 or more carbon atoms, can be used. The substituents having 8 or more carbon atoms are preferably non-polymerizable substituents, that is, substituents that do not have repeating units. Specifically, 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, heterocyclic groups having 8 or more carbon atoms, etc., 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. The upper limit is not particularly limited, but is preferably 24 or less, more preferably 20 or less, even more preferably 18 or less, and particularly preferably 16 or less. The carbon number of a substituent indicates the number of carbon atoms that make up that substituent. If this substituent has further substituents, the number of carbon atoms that make up those further substituents is also included in the count.

[0088] Linking group L Ｃ２ The elements are not particularly limited, but for example, alkylene groups (preferably with 1 to 12 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3 carbon atoms), alkenylene groups (preferably with 2 to 6 carbon atoms, more preferably 2 to 3 carbon atoms), arylene groups (preferably with 6 to 24 carbon atoms, more preferably 6 to 10 carbon atoms), oxygen atoms, sulfur atoms, imino groups (-NR Ｎ -: R Ｎ The group represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Examples include a carbonyl group, a phosphate linking group (-O-P(OH)(O)-O-), a phosphonic acid linking group (-P(OH)(O)-O-), or a group relating to a combination thereof. 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, 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 -CO-N(R Ｎ )-group (R Ｎ The above is true.) is particularly preferred, and the -CO-O- group is most preferred. Linking group L Ｃ２ The number of atoms constituting the group is preferably 1 to 36, more preferably 1 to 24, even more preferably 1 to 12, and particularly preferably 1 to 6. The number of linked atoms in the linking group is preferably 10 or less, and more preferably 8 or less. The lower limit is 1 or more. The above number of linked atoms refers to the minimum number of atoms that connect predetermined structural parts. For example, in the case of -C(=O)-O-, the number of atoms constituting the linking group is 3, but the number of linked atoms is 2.

[0089] Substructures incorporated into the main chain, linking group L Ｃ２ The substituents having 8 or more carbon atoms 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 the functional groups selected from functional group (a) are preferred.

[0090] 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).

[0091] In formula (1-1), R １ R represents a hydrogen atom or an alkyl group (preferably with 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms). 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 functional group (a) are preferred, such as halogen atoms.

[0092] 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 １It bonds directly to the carbon atom in the above formula. ) and R ２ Linking group L in the above formula to which the carbon atom and substituent are bonded. Ｃ２ A group consisting of a substituent (where the substituent is R １ The carbon atom in the above formula to which the linking group L is attached. Ｃ２ It is joined via R. ) and it includes R. ２ A substituent having 8 or more carbon atoms, and further R ２ The linking group L may have Ｃ２ As stated above, R ２ As such, a long-chain alkyl group having 8 or more carbon atoms, -C(=O)-O, is particularly preferred. In the above formula (1-1), R １ The carbon atom adjacent to the carbon atom to which the compound 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 groups other than functional group (a) are preferred.

[0093] The constituent component C2 is preferably, for example, a constituent component derived from a compound having eight or more carbon atoms among the (meth)acrylic compounds (M1) described later, or a constituent component derived from a compound having eight or more carbon atoms among the other polymerizable compounds (M2) described later, and a long-chain alkyl ester compound of (meth)acrylic acid (having eight or more carbon atoms) is preferred. Specific examples of constituent component C2 include those found in the specific examples of linear polymers described later, but the present invention is not limited to these.

[0094] The content of component C2 in the linear polymer is not particularly limited and is selected from the range of 0 to 100% by mass. The above content of component C2 is preferably 20 to 99.9% by mass, more preferably 30 to 99.5% by mass, and even more preferably 30 to 99% by mass, in terms of the dispersibility of the linear polymer. When the linear polymer is a (meth)acrylic polymer, the content of component C2 in the linear polymer is appropriately determined considering the above content, for example, it is particularly preferably 50 to 99% by mass, and most preferably 80 to 99% by mass. When the linear polymer is a hydrocarbon polymer, the content of component C2 in the linear polymer can be the above content, but for example, it is also preferable to set it to 1 to 80% by mass, most preferably 1 to 50% by mass, and can also be set to 20 to 50% by mass. When the linear polymer is a vinyl polymer, the content of component C2 in the linear polymer can be as described above, but it is also preferable to set it to, for example, 1 to 80% by mass, and most preferably 1 to 50% by mass. When the linear polymer has multiple components C2, the content of component C1 is the total amount.

[0095] (Other Components) The linear polymer may contain components that do not fall under either component C1 having the above-mentioned functional group (a) or component C2 having the above-mentioned substituent having 8 or more carbon atoms ("other components"). The other components are not particularly limited as long as they can constitute a linear polymer and can be appropriately selected depending on the type of linear polymer, etc. For example, among the (meth)acrylic compounds (M1) and other polymerizable compounds (M2) described later, examples include components derived from compounds that do not have substituents having 8 or more carbon atoms and the above-mentioned functional group (a). The content of the other components in the linear polymer 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. When the linear polymer contains other components, for example, it is preferably 1 to 99% by mass, more preferably 5 to 80% by mass, and even more preferably 8 to 60% by mass.

[0096] The following describes suitable chain polymerization polymers in detail. (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. The styrene-based thermoplastic elastomer or its hydrogenated product is not particularly limited, but examples 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 each of 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.

[0097] The hydrocarbon polymer may also preferably contain, in addition to the constituent components of the hydrocarbon polymer described above (e.g., styrene), the constituent components C1 and C2 mentioned above, for example, constituent components derived from polymerizable cyclic carboxylic acid anhydrides such as maleic anhydride. Furthermore, these constituent components also include, for example, constituent components obtained by introducing the functional group (a) mentioned above into copolymerized constituent components through various reactions. The content of constituent components in the hydrocarbon polymer is not particularly limited and can be appropriately selected and set within an appropriate range considering conditions (4) and other physical properties. The content of constituent component C1, constituent component C2 and the other constituent components in the total constituent components of the hydrocarbon polymer is as described above.

[0098] (Fluoropolymer) Examples of fluoropolymers include polytetrafluoroethylene (PTFE), polyvinyl difluoride (PVdF), copolymer of polyvinyl difluoride and hexafluoropropylene (PVdF-HFP), and copolymer of polyvinyl difluoride, hexafluoropropylene, and tetrafluoroethylene (PVdF-HFP-TFE). The content of the constituent components in the fluoropolymer is not particularly limited and is appropriately selected considering the conditions (4) and other physical properties, and can be set to the following range, for example. The content of the above constituent component C1, above constituent component C2, and above other constituent components in the total constituent components constituting the fluoropolymer is as described above. For example, in PVdF-HFP, the copolymerization ratio [PVdF:HFP] (mass ratio) of PVdF and HFP is not particularly limited, but 9:1 to 5:5 is preferred, and 9:1 to 7:3 is more preferred from the viewpoint of adhesion. In PVdF-HFP-TFE, the copolymerization ratio [PVdF:HFP:TFE] (mass ratio) of PVdF, HFP, and TFE is not particularly limited, but is preferably 20-90:5-50:5-30, and more preferably 25-80:10-35:5-25.

[0099] (Vinyl Polymer) Examples of vinyl polymers include polymers containing, for example, 50% by mass 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. In addition to the components derived from vinyl monomers, it is also preferable that this vinyl polymer has at least one of the above-mentioned components C1 and C2, and furthermore, components derived from the (meth)acrylic compound (M1) that forms the (meth)acrylic polymer described later. The content of components in the vinyl polymer is not particularly limited and is appropriately selected considering condition (4) and other physical properties, and can be set to, for example, the following range. It is preferable that the content of components derived from vinyl monomers in all components constituting the vinyl polymer is the same as the content of components derived from (meth)acrylic compounds (M1) in the (meth)acrylic polymer. Here, if components C1 and C2 are components derived from vinyl monomers, the content of these components is included in the content of components derived from vinyl monomers. The content of component C1, component C2, and the other components in the total components constituting the vinyl polymer is as described above. The content of the component derived from the (meth)acrylic compound (M1) is not particularly limited as long as it is 50% by mass or less in the polymer, but is preferably 10 to 45% by mass, and preferably 20 to 45% by mass.

[0100] ((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)acrylonitrile compounds is preferred. A polymer having a component derived from this (meth)acrylic compound (M1) and at least one of component C1 and component C2 is also preferred. A polymer containing a component derived from other polymerizable compounds (M2) is also preferred.

[0101] 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. The polymer chain of the (meth)acrylic acid ester compound is not particularly limited, but an alkylene oxide polymer chain is preferred, and a polymer chain consisting of an alkylene oxide with 2 to 4 carbon atoms is more preferred. The degree of polymerization of the polymer chain is not particularly limited and can be set as appropriate. The ends of the polymer chain are usually bonded to an alkyl group or an aryl group. Examples of (meth)acrylamide compounds include N-unsubstituted (meth)acrylamide compounds, N-mono or disubstituted (meth)acrylamide compounds, and more specifically, N-unsubstituted (meth)acrylamide compounds, N-alkyl (meth)acrylamide compounds, N,N-dialkyl (meth)acrylamide compounds, N-aryl (meth)acrylamide compounds, and N,N-diaryl (meth)acrylamide compounds are preferred. Substituents that replace the nitrogen atom in the acrylamide compound include R as described in component C1 above, or terminal groups bonded to the ends of the amide group, with alkyl groups or aryl groups being preferred.

[0102] Other polymerizable compounds (M2) are not particularly limited and include vinyl aromatic compounds such as styrene compounds, vinylnaphthalene compounds, and vinylcarbazole compounds, vinyl compounds such as allyl compounds, vinyl ether compounds, vinyl ester compounds, dialkyl itaconates, unsaturated carboxylic acid anhydrides, cyclic olefin compounds, diene compounds, vinyl carboxylic acid ester compounds, and 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. Substituents are not particularly limited and preferably include groups selected from substituent Z described later.

[0103] The content of the constituent components in the (meth)acrylic polymer is not particularly limited and can be appropriately selected according to condition (4), and for example, can be set within the following range. The content of the constituent component derived from the (meth)acrylic compound (M1) in all the constituent components constituting the (meth)acrylic polymer is not particularly limited and can be appropriately set in the range of 0 to 100% by mass. The upper limit can be, for example, 90% by mass. Here, if constituent components C1 and C2 are constituent components derived from the (meth)acrylic compound (M1), the content of these constituent components is included in the content of the constituent components derived from the (meth)acrylic compound (M1). The content of the above constituent component C1, the above constituent component C2, and the above other constituent components in all the constituent components constituting the (meth)acrylic polymer is 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 less than 50% by mass, preferably 1 to 30% by mass, more preferably 1 to 20% by mass, and even more preferably 2.5 to 20% by mass.

[0104] As the (meth)acrylic compound (M1) and other polymerizable compound (M2) that lead to the constituent components of (meth)acrylic polymers and vinyl polymers, compounds represented by the following formula (b-1) are preferred. This compound is preferably different from the compound that leads to constituent component C1 or the compound that leads to constituent component C2.

[0105]

[0106] In the formula, R １ This represents 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.

[0107] 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 groups with 8 or more carbon atoms or alkyl groups with 7 or fewer carbon atoms are preferred.

[0108] L １ This is a linking group, and is not particularly limited, but examples include linking groups in the above-mentioned constituent components having substituents with 8 or more carbon atoms. -CO-O- group, -CO-N(R Ｎ )-group (R ＮThe above is preferred. The above linking group may have any substituents. 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.

[0109] 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 This is used as a substituent (alkyl group).

[0110] 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 the compound that leads to component C1 or the compound that leads to component C2.

[0111]

[0112] R １ , n is equivalent to the above equation (b-1). R ３ R ２ This is synonymous with L. ２ is a linking group, and the above L １ The description below can be preferably applied. ３ is a linking group, and the above L １ The above description can be preferably applied, and an alkylene group having 1 to 6 carbon atoms (preferably 1 to 3) is preferred. m is an integer from 1 to 200, preferably an integer from 1 to 100, and more preferably an integer from 1 to 50.

[0113] In the above formulas (b-1) to (b-3), the carbon atom that forms the polymerizable group is R １ A carbon atom that is not bonded is an unsubstituted carbon atom (H ２ Although it is expressed as C=), it may have substituents. There are no particular restrictions on substituents, but for example, R １The above-mentioned groups are examples of groups that can take this property. 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. Substituents other than functional group (a) are acceptable, and examples include groups selected from substituent Z described later, specifically halogen atoms, etc.

[0114] 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, with groups other than the functional group (a) described above being preferred.

[0115] - Substituent Z - Alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, e.g., methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl group (preferably an alkenyl group having 2 to 20 carbon atoms, e.g., vinyl, allyl, oleyl, etc.), alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, e.g., ethynyl, butadiinyl, phenylethynyl, etc.), cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, e.g., cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.) In this invention, the term alkyl group usually includes cycloalkyl groups, but this is described separately here.), aryl groups (preferably aryl groups having 6 to 26 carbon atoms, e.g., phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl groups (preferably aralkyl groups having 7 to 23 carbon atoms, e.g., benzyl, phenethyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, more preferably heterocyclic groups of 5 or 6 members having at least one oxygen atom, a sulfur atom, or a nitrogen atom. Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups.For example, tetrahydropyran ring group, tetrahydrofuran ring group, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, pyrrolidone group, etc.), alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms, for example, phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy group (a group in which an -O- group is bonded to the above heterocyclic group), alkoxycarbonyl group (preferably Or, alkoxycarbonyl groups having 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, etc.), aryloxycarbonyl groups (preferably aryloxycarbonyl groups having 7 to 26 carbon atoms, for example, phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), heterocyclic oxycarbonyl groups (groups in which an -O-CO- group is bonded to the above heterocyclic group), amino groups (preferably amino groups having 0 to 20 carbon atoms, alkylamino groups, arylamino groups, for example, amino(-NH). ２), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl group (preferably a sulfamoyl group having 0 to 20 carbon atoms, for example, N,N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyl group (including alkylcarbonyl group, alkenylcarbonyl group, alkynylcarbonyl group, arylcarbonyl group, heterocyclic carbonyl group, preferably an acyl group having 1 to 20 carbon atoms, for example, acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotinoyl, etc.), acyl Oxy groups (including alkylcarbonyloxy groups, alkenylcarbonyloxy groups, alkynylcarbonyloxy groups, and heterocyclic carbonyloxy groups, preferably acyloxy groups having 1 to 20 carbon atoms, for example, acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyloxy, acryloyloxy, methacryloyloxy, crotonoyloxy, nicotinoyloxy, etc.), allyloxy groups (preferably allyloxy groups having 7 to 23 carbon atoms, for example, benzoyloxy, naphthoyloxy, etc.), carbamoyl groups (preferably carbamoyl groups having 1 to 20 carbon atoms, for example, N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), acylamino group (preferably an acylamino group having 1 to 20 carbon atoms, e.g., acetylamino, benzoylamino, etc.), alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms, e.g., methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio group (preferably an arylthio group having 6 to 26 carbon atoms, e.g., phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), heterocyclic thio group (a group in which an -S- group is bonded to the above heterocyclic group), alkylsulfonyl group (preferably an alkylsulfonyl group having 1 to 20 carbon atoms, e.g., methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl group (preferably carbon Arylsulfonyl groups with 6 to 22 carbon atoms, for example, benzenesulfonyl), alkylsilyl groups (preferably alkylsilyl groups with 1 to 20 carbon atoms, for example, monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl), arylsilyl groups (preferably arylsilyl groups with 6 to 42 carbon atoms, for example, triphenylsilyl), alkoxysilyl groups (preferably alkoxysilyl groups with 1 to 20 carbon atoms, for example, monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl), aryloxysilyl groups (preferably aryloxysilyl groups with 6 to 42 carbon atoms, for example, triphenyloxysilyl), phosphoryl groups (preferably phosphate groups with 0 to 20 carbon atoms, for example, -OP(=O)(R, Ｐ ) ２ ), phosphonyl group (preferably a phosphonyl group having 0 to 20 carbon atoms, for example, -P(=O)(R Ｐ ) ２ ), phosphenyl group (preferably a phosphenyl group having 0 to 20 carbon atoms, for example, -P(R Ｐ ) ２ ), phosphonic acid group (preferably a phosphonic acid group having 0 to 20 carbon atoms, for example, -PO(OR Ｐ ) ２ Examples include sulfo groups (sulfonic acid groups), carboxyl groups, hydroxyl groups, sulfanyl groups, cyano groups, and halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.). Ｐis a hydrogen atom or a substituent (preferably a group selected from substituent Z). Furthermore, each of the groups listed as substituent Z may be further substituted with substituent Z. The alkyl group, alkylene group, alkenyl group, alkenylene group, alkynyl group and / or alkynylene group, etc. may be cyclic or linear, and may be linear or branched.

[0116] Chain polymers can be synthesized by selecting raw material compounds and polymerizing them using known methods. The method for incorporating functional group (a) is not particularly limited and includes, for example, copolymerization of a compound having functional group (a), using a polymerization initiator or chain transfer agent having (or producing) the above-mentioned functional group (a), utilizing polymer reactions, ene reactions to double bonds, ene-thiol reactions, or ATRP (Atom Transfer Radical Polymerization) polymerization using a copper catalyst. Alternatively, functional group (a) can be introduced by using functional groups present in the main chain, side chains, or terminals of the polymer as reaction sites. For example, functional group (a) can be introduced by using a compound having functional group (a) and various reactions with carboxylic acid anhydride groups in the polymer chain.

[0117] Specific examples of linear polymers are listed below, but the present invention is not limited to these. In the linear polymers listed below, Me represents a methyl group, alkyl groups having 4 or more carbon atoms are linear alkyl groups, and the number in the lower right corner of each component indicates the content (mass%) of that component.

[0118]

[0119]

[0120]

[0121] (Physical properties or characteristics of linear polymers) Linear polymers preferably have the following physical properties or characteristics. The water content of the linear polymer is preferably 100 ppm (by mass) or less. The linear polymer may be obtained by crystallizing and drying the linear polymer, or a solution of the linear polymer may be used as is. Linear polymers are preferably amorphous. In the present invention, a linear polymer being "amorphous" typically means that no endothermic peak due to crystal melting is observed when measured at the glass transition temperature.

[0122] Adsorption rate A of linear polymer to active material ＡＣ (%) is not particularly limited, but if it is too small, the linear polymer will not adsorb to the active material and the active material will not be able to be dispersed in the dispersion medium. On the other hand, adsorption rate A ＡＣ If the adsorption rate is too high, the linear polymer will excessively adsorb to the active material, making it easier for the active material to aggregate. Adsorption rate A to positive electrode active material ＡＣ The adsorption rate A to the negative electrode active material is more preferably 3-40% and even more preferably 5-30% in terms of the dispersibility of the positive electrode active material. ＡＣ Adsorption rate A is more preferably 2-50% and even more preferably 3-40% in terms of the dispersibility of the negative electrode active material. ＡＣ This value is measured using the active material and dispersion medium contained in the electrode composition, and is an index indicating the degree to which the linear polymer is adsorbed onto the active material in this dispersion medium. Here, the adsorption of the linear polymer onto the active material includes not only physical adsorption but also chemical adsorption, as described above. Adsorption rate A of linear polymer onto the active material ＡＣ (%) indicates the adsorption rate of the linear polymer to the fibrous conductive additive, except when the active material is used instead of the fibrous conductive additive. ＦＡ It can be measured in the same manner. Adsorption rate A ＡＣ (%) represents the adsorption rate A ＦＡ It can be adjusted in the same way.

[0123] Adsorption rate A of linear polymers to inorganic solid electrolytes ＳＥ(%) is not particularly limited, but if it is too small, the linear polymer will not be adsorbed onto the inorganic solid electrolyte, and the inorganic solid electrolyte will not be able to be dispersed in the dispersion medium. On the other hand, adsorption rate A ＳＥ If the adsorption rate is too high, the linear polymer will excessively adsorb to the inorganic solid electrolyte, making it easier for the inorganic solid electrolyte to aggregate. ＳＥ Adsorption rate A is preferably 1-70% and more preferably 2-50% in terms of the dispersibility of the inorganic solid electrolyte. ＳＥ This value is measured using the inorganic solid electrolyte and dispersion medium contained in the electrode composition, and is an index indicating the degree to which the linear polymer is adsorbed onto the inorganic solid electrolyte in this dispersion medium. Here, the adsorption of the linear polymer onto the inorganic solid electrolyte includes not only physical adsorption but also chemical adsorption, as described above. Adsorption rate A of linear polymer onto inorganic solid electrolyte ＳＥ (%) indicates the adsorption rate of the linear polymer to the fibrous conductive additive, except when using an inorganic solid electrolyte instead of the fibrous conductive additive. ＦＡ It can be measured in the same way as [another method].

[0124] The electrode composition of the present invention may contain one or more linear polymers. The content of the linear polymer in the electrode composition is not particularly limited and can be set as appropriate. For example, 0.1 to 10% by mass is preferred, 0.5 to 8% by mass is more preferred, and 0.5 to 5% by mass is even more preferred, based on 100% by mass of solids. In the present invention, based on 100% by mass of solids, the mass ratio of the total mass of the inorganic solid electrolyte and positive electrode active material to the mass of the linear polymer [(mass of inorganic solid electrolyte + mass of positive electrode active material) / (mass of linear polymer)] is preferably in the range of 1,000 to 1. This ratio is further more preferably 500 to 2, and even more preferably 100 to 10. When the electrode composition contains two or more linear polymers, the content of the linear polymers is the total content.

[0125] <Dispersion Medium> The electrode composition of the present invention contains a dispersion medium that disperses or dissolves each of the above components. Such a dispersion medium can be any organic compound that is liquid in the environment in which it is used, for example, various organic solvents, specifically alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, nitrile compounds, ester compounds, etc. The dispersion medium can be either a nonpolar dispersion medium (hydrophobic dispersion medium) or a polar dispersion medium (hydrophilic dispersion medium), but a nonpolar dispersion medium is preferred in that it can exhibit excellent dispersibility. A nonpolar dispersion medium generally means a substance with low affinity for water, and in the present invention, for example, ester compounds, ketone compounds, ether compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, etc.

[0126] 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.

[0127] Examples of ether compounds include alkylene glycols (diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, etc.), alkylene glycol monoalkyl ethers (ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, etc.), alkylene glycol dialkyl ethers (ethylene glycol dimethyl ether, etc.), dialkyl ethers (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), and cyclic ethers (tetrahydrofuran, dioxane (including the 1,2-, 1,3-, and 1,4- isomers), etc.).

[0128] Examples of amide compounds include N,N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropanamide, and hexamethylphosphoric triamide.

[0129] Examples of amine compounds include triethylamine, diisopropylethylamine, and tributylamine. Examples of ketone compounds include acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone, cyclohexanone, cycloheptanone, dipropyl ketone, dibutyl ketone, diisopropyl ketone, diisobutyl ketone (DIBK), isobutylpropyl ketone, sec-butylpropyl ketone, pentylpropyl ketone, and butylpropyl ketone. Examples of aromatic hydrocarbon compounds include benzene, toluene, xylene, mesitylene, and perfluorotoluene. Examples of aliphatic hydrocarbon compounds include hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane, decalin, paraffin, gasoline, naphtha, kerosene, and diesel fuel. Examples of nitrile compounds include acetonitrile, propionitrile, and isobutyronitrile. Examples of ester compounds include ethyl acetate, propyl acetate, butyl acetate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, butyl pentanoate, pentyl pentanoate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, isobutyl isobutyrate, propyl pivalate, isopropyl pivalate, butyl pivalate, and isobutyl pivalate.

[0130] In the present invention, ether compounds, ketone compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, and ester compounds are preferred, and ester compounds, ketone compounds, aromatic hydrocarbon compounds, or ether compounds are more preferred.

[0131] The number of carbon atoms in the compounds constituting the dispersion medium is not particularly limited, but is preferably 2 to 30, more preferably 4 to 20, even more preferably 6 to 15, and particularly preferably 7 to 12.

[0132] The boiling point of the dispersion medium at normal pressure (1 atmosphere: 101325 Pa) is not particularly limited, but is preferably 50°C or higher, and more preferably 70°C or higher. The upper limit is preferably 250°C or lower, and more preferably 220°C or lower.

[0133] The electrode composition of the present invention may contain one or more dispersion media. Examples of compositions containing two or more dispersion media include xylene (a mixture of xylene isomers with a mixed molar ratio of ortho-isomer:para-isomer:meta-isomer = 1:5:2), mixed xylene (a mixture of o-xylene, p-xylene, m-xylene, and ethylbenzene), and the like. In the present invention, the content of the dispersion media in the electrode composition can be appropriately set within the range that satisfies the above-mentioned solid content (condition (5)). However, since the electrode composition of the present invention exhibits excellent dispersibility and battery characteristics even with a general range of solid content, it can also be set to a lower content than condition (5). For example, the content of the dispersion media in the electrode composition can be set to 30% by mass or more, 50% by mass or more, or 60% by mass or more.

[0134] <Lithium Salt> 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.

[0135] <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.

[0136] Furthermore, the electrode composition of the present invention may contain conductive additives other than fibrous conductive additives as other additives. Examples of such conductive additives include particulate or granular conductive additives (sometimes referred to as "particulate conductive additives" in the present invention). In the present invention, particulate conductive additives refer to those with an aspect ratio outside the above range, for example, 0.5 to 1.5. There are no particular restrictions on the particulate conductive additives, and those commonly known as particulate conductive additives can be used. Examples of materials that form particulate conductive additives include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, Ketjen black, and furnace black, amorphous carbon such as needle coke, carbonaceous materials such as graphene or fullerene, metallic materials such as copper and nickel, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives. The total content of particulate conductive additives in the electrode composition is not particularly limited and can be determined as appropriate. For example, it is preferable that the solid content is 20% by mass or less out of 100% by mass.

[0137] (Preparation of Electrode Composition) The electrode composition of the present invention can be prepared by conventional methods. For example, an inorganic solid electrolyte, a positive electrode active material, a fibrous conductive additive, a linear polymer, a dispersion medium, a lithium salt as appropriate, 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, orbital mixers, and narrow-gap dispersers. Each component may be mixed together or sequentially. The mixing environment is not particularly limited, but examples include dry air (dew point of -20°C or below) or in an inert gas (e.g., argon gas, helium gas, nitrogen gas). The mixing conditions are also not particularly limited and can be set as appropriate; for example, the mixing temperature can be 15 to 40°C. Furthermore, the rotation speed of the self-rotating mixer, etc., can be set to 200 to 3,000 rpm (rotation per minute). The mixing time is not particularly limited and can be appropriately determined according to the dispersibility of the solid particles, and can typically be 1 to 180 minutes.

[0138] [Electrode Sheet for All-Solid-State Secondary Battery] The electrode sheet for all-solid-state secondary battery of the present invention is a sheet-like molded body capable of forming the active material layer (particularly the positive electrode active material layer) of an all-solid-state secondary battery, and includes various embodiments depending on its application. For example, it is a sheet that is preferably used as an electrode, or as a laminate of an electrode and a solid electrolyte layer. In the present invention, each layer constituting the electrode sheet for all-solid-state secondary battery may be a single-layer structure or a multi-layer structure.

[0139] The electrode sheet for all-solid-state secondary batteries has a positive electrode active material layer on a substrate formed from the electrode composition of the present invention. Therefore, the layer formed from the electrode composition of the present invention is formed from components derived from the electrode composition (excluding the dispersion medium), and the solid particles are tightly adhered to or bound to it. The active material layer formed from the electrode composition of the present invention is presumed to be dispersed or present in a state in which solid particles (inorganic solid electrolyte, positive electrode active material, especially fibrous conductive additive) and linear polymer are almost uniformly mixed, and the presence of aggregates of fibrous conductive additive in the active material layer can be suppressed. Furthermore, the surface of this active material layer is flat, which can suppress the occurrence of short circuits in the all-solid-state secondary battery. It is preferable that the surface of the active material layer is about the same as the average height of the roughness curve elements in the examples described later (in the present invention, this may simply be referred to as "average height Rc"). By manufacturing an all-solid-state secondary battery using an electrode sheet for all-solid-state secondary batteries having such an active material layer, it is possible to realize an all-solid-state secondary battery with excellent battery performance such as charge / discharge characteristics and battery life, and furthermore, a high-output all-solid-state secondary battery that is less prone to short circuits. While all-solid-state secondary batteries tend to experience a decrease in performance in high-temperature environments depending on the type, dispersion, and aggregation of conductive additives, the all-solid-state secondary battery of the present invention has a positive electrode active material layer in which the fibrous conductive additive is dispersed almost uniformly with few aggregates, resulting in high electronic conductivity and enabling the realization of excellent battery performance even in high-temperature environments.

[0140] The substrate is not particularly limited as long as it can support the positive electrode active material layer, and examples include sheets (plate-like bodies) of materials such as current collectors, organic materials, and inorganic materials, as described later. Examples of organic materials include various polymers, specifically polyethylene terephthalate, polypropylene, polyethylene, and cellulose. Examples of inorganic materials include glass and ceramics.

[0141] Thus, the electrode sheet for all-solid-state secondary batteries of the present invention is suitably used as a sheet-like member for forming the active material layer of an all-solid-state secondary battery. The electrode sheet for all-solid-state secondary batteries can be incorporated into an all-solid-state secondary battery either as an active material layer after appropriately peeling off the substrate, or as an electrode (a laminate of a current collector and an active material layer) while still attached to the substrate.

[0142] The electrode sheet for all-solid-state secondary batteries of the present invention (also simply referred to as "electrode sheet") may be any electrode sheet having a positive electrode active material layer (positive electrode sheet), and may be a positive electrode sheet in which the positive electrode active material layer is formed on a substrate (current collector), or a positive electrode sheet without a substrate and formed from the positive electrode active material layer (positive electrode sheet with the substrate peeled off). This electrode sheet is usually a sheet having a current collector and a positive electrode active material layer, but it also includes embodiments having a current collector, a positive electrode active material layer and a solid electrolyte layer in this order, as well as embodiments having a current collector, a positive electrode active material layer, a solid electrolyte layer and a negative electrode active material layer in this order. The positive electrode active material layer of the electrode sheet is formed from the electrode composition of the present invention. The content of each component in the positive electrode active material layer formed from the electrode composition of the present invention is not particularly limited, but preferably it is synonymous with the content of each component in the solid content of the electrode composition of the present invention. The thickness of each layer constituting the electrode sheet of the present invention is the same as the thickness of each layer described later in the all-solid-state secondary battery. The electrode sheet may have other layers. Other layers include, for example, a protective layer (release sheet), a current collector, and a coating layer.

[0143] [Method for Manufacturing Electrode Sheets for All-Solid-State Secondary Batteries] The method for manufacturing electrode sheets for all-solid-state secondary batteries of the present invention is not particularly limited, and they can be manufactured by forming a positive electrode active material layer using the electrode composition of the present invention. For example, preferably, a method is used in which a film is formed (coated and dried) on a substrate or current collector (may be via other layers) to form a layer (coated and dried layer) made of the electrode composition. This makes it possible to produce electrode sheets for all-solid-state secondary batteries having a substrate or current collector and a coated and dried layer. Here, the coated and dried layer refers to a layer formed by coating the electrode composition of the present invention and drying the dispersion medium (i.e., a layer made using the electrode composition of the present invention, and consisting of a composition obtained by removing the dispersion medium from the electrode composition of the present invention). The coated and dried layer and the constituent layer may have residual dispersion medium as long as it does not impair the effects of the present invention, and the residual amount can be, for example, 3% by mass or less in each layer. In the method for manufacturing electrode sheets for all-solid-state secondary batteries of the present invention, each step such as coating and drying will be explained in the method for manufacturing all-solid-state secondary batteries below.

[0144] In this way, an electrode sheet for an all-solid-state secondary battery having a positive electrode active material layer prepared by appropriately pressurizing the coated and dried layer can be manufactured. The pressurizing conditions and other details will be explained later in the section on the manufacturing method of the all-solid-state secondary battery. Furthermore, in the manufacturing method of the electrode sheet for an all-solid-state secondary battery of the present invention, the substrate, protective layer (especially the release sheet), etc., can also be peeled off.

[0145] [All-Solid-State Secondary Battery] The all-solid-state secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer facing the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The all-solid-state secondary battery of the present invention is not particularly limited in its other configurations, as long as it has a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer, and for example, known configurations relating to all-solid-state secondary batteries can be adopted. Preferably, the positive electrode active material layer has a positive electrode current collector laminated on the surface opposite to the solid electrolyte layer to constitute the positive electrode, and preferably the negative electrode active material layer has a negative electrode current collector laminated on the surface opposite to the solid electrolyte layer to constitute the negative electrode. In the present invention, each constituent layer (including current collectors, etc.) constituting the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

[0146] In the all-solid-state secondary battery of the present invention, the positive electrode active material layer is formed with the electrode composition of the present invention. In the present invention, forming the positive electrode active material layer of an all-solid-state secondary battery with the electrode composition of the present invention includes the embodiment of forming the positive electrode active material layer with the electrode sheet for all-solid-state secondary batteries of the present invention (however, if the sheet has layers other than the layer formed with the electrode composition of the present invention (excluding the current collector), then the sheet from which these layers have been removed). The all-solid-state secondary battery of the present invention, in which the positive electrode active material layer is formed with the electrode composition of the present invention, exhibits excellent battery performance as described above. In the present invention, each constituent layer (including the current collector, etc.) constituting the all-solid-state secondary battery may be a single-layer structure or a multi-layer structure.

[0147] <Positive Electrode Active Material Layer> The positive electrode 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. The thickness of the positive electrode active material layer is not particularly limited, but is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm.

[0148] <Solid Electrolyte Layer, Negative Electrode Active Material Layer> The solid electrolyte layer and the negative electrode active material layer can be formed from known materials. The solid electrolyte layer preferably contains the inorganic solid electrolyte having conductivity for ions of metals belonging to Group 1 or Group 2 of the periodic table, and contains a binder such as the linear polymer or commonly used polymers mentioned above, and any of the above-mentioned components, and usually does not contain positive electrode active material and / or negative electrode active material. The negative electrode active material layer preferably contains the inorganic solid electrolyte having conductivity for ions of metals belonging to Group 1 or Group 2 of the periodic table, a negative electrode active material described later, and a conductive additive such as a fibrous conductive additive or a particulate conductive additive, and contains a binder such as the linear polymer or commonly used polymers mentioned above, and any of the above-mentioned components. In an all-solid-state secondary battery, the negative electrode active material layer can be a lithium metal layer. Examples of lithium metal layers include layers formed by depositing or molding lithium metal powder, lithium foil, and lithium vapor-deposited films. The thickness of the lithium metal layer can be, for example, 1 to 500 μm, regardless of the thickness of the negative electrode active material layer described above. The thicknesses of the negative electrode active material layer and the solid electrolyte layer are not particularly limited, but are preferably, for example, 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.

[0149] <Current Collector> The positive electrode active material layer and the negative electrode active material layer may each have a current collector on the side opposite to the solid electrolyte layer. Electron conductors are preferred as the positive electrode current collector and the negative electrode current collector. In the present invention, either the positive electrode current collector or the negative electrode current collector, or both together, may be simply referred to as the current collector. As the material for forming the positive electrode current collector, in addition to aluminum, aluminum alloys, stainless steel, nickel, and titanium, a material in which carbon, nickel, titanium, or silver has been treated on the surface of aluminum or stainless steel (a thin film has been formed) is preferred, with aluminum and aluminum alloys being more preferred among these. As the material for forming the negative electrode current collector, in addition to aluminum, copper, copper alloys, stainless steel, nickel, and titanium, a material in which carbon, nickel, titanium, or silver has been treated on the surface of aluminum, copper, copper alloys, or stainless steel is preferred, with aluminum, copper, copper alloys, and stainless steel being more preferred.

[0150] While film sheets are typically used as the shape of the current collector, nets, punched materials, lath materials, porous materials, foams, and molded fiber bundles can also be used. The thickness of the current collector is not particularly limited, but 1 to 500 μm is preferred. It is also preferable to create an uneven surface on the current collector surface through surface treatment.

[0151] <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.

[0152] <Housing> The all-solid-state secondary battery of the present invention may be used as an all-solid-state secondary battery with the above structure, depending on the application, but in order to take the form of 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 housing for the positive electrode side and a housing for the negative electrode side, and electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. It is preferable that the housing for the positive electrode side and the housing for the negative electrode side are joined and integrated via a gasket to prevent short circuits.

[0153] (Negative Electrode Active Material) The negative electrode active material that forms the negative electrode active material layer of an all-solid-state secondary battery is an active material that can insert and release ions of metals belonging to Group 1 or Group 2 of the periodic table, and is preferably one that can reversibly insert and release lithium ions. The material is not particularly limited as long as it has the above 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 increase in capacity of the all-solid-state secondary battery.

[0154] Carbonaceous materials used as negative electrode active materials are materials that consist substantially of carbon. Examples include petroleum pitch, carbon black such as acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor-grown graphite, etc.), and carbonaceous materials obtained by firing various synthetic resins such as PAN (polyacrylonitrile) resins or furfuryl alcohol resins. Furthermore, examples include various types of carbon fibers such as PAN-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polyvinyl alcohol)-based carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers, as well as mesophase microspheres, graphite whiskers, and plate-shaped graphite. These carbonaceous materials can also be divided into hard carbonaceous materials (also called hard carbon) and graphitic carbonaceous materials depending on the degree of graphitization. Furthermore, the carbonaceous material preferably has the interplanar spacing or density and crystallite size described in Japanese Patent Publication No. 62-22066, Japanese Patent Publication No. 2-6856, and Japanese Patent Publication No. 3-45473. The carbonaceous material does not need to be a single material; a mixture of natural graphite and artificial graphite described in Japanese Patent Publication No. 5-90844, graphite having a coating layer described in Japanese Patent Publication No. 6-4516, etc., can also be used. Hard carbon or graphite is preferably used as the carbonaceous material, and graphite is more preferably used.

[0155] The oxides of metals or metalloid elements used as negative electrode active materials are not particularly limited as long as they are oxides capable of intercalating and releasing lithium, and include metal oxides, composite oxides of metal elements, or composite oxides of metal elements and metalloid elements (collectively referred to as metal composite oxides), and metalloid oxides. Among these oxides, amorphous oxides are preferred, and chalcogenides, which are reaction products of metal elements and elements of Group 16 of the periodic table, are also preferred. In the present invention, metalloid elements refer to elements that exhibit properties intermediate between metal elements and 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° 2θ is 100 times or less, more preferably 5 times or less, the intensity of the diffraction line at the peak of the broad scattering band observed at 20° to 40° 2θ, and it is particularly preferable that there are no crystalline diffraction lines.

[0156] Among the group of compounds consisting of amorphous oxides and chalcogenides described above, amorphous oxides of metalloid elements or the chalcogenides described above are more preferred, and oxides (compounds) consisting of one element selected from groups 13 (IIIB) to 15 (VB) of the periodic table (for example, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) or a combination of two or more such elements, or chalcogenides are particularly preferred. Specific examples of preferred amorphous oxides and chalcogenides include, for example, Ga ２ O ３ , GeO, PbO, PbO ２ Pb ２ O ３ Pb ２ O ４ Pb ３ O ４ Sb ２ O ３ Sb ２ O ４ Sb ２ O ８Bi ２ O ３ Sb ２ O ８ Si ２ O ３ Sb ２ O ５ , Bi ２ O ３ , Bi ２ O ４ , GeS, PbS, PbS ２ Sb ２ S ３ or Sb ２ S ５ Preferably, the following can be used in combination with amorphous oxides mainly composed of Sn, Si, and Ge: carbonaceous materials capable of intercalating and / or releasing lithium ions or lithium metal, elemental lithium, lithium alloys, and negative electrode active materials that can be alloyed with lithium.

[0157] From the viewpoint of high current density charge-discharge characteristics, oxides of metals or metalloid elements, particularly metal (composite) oxides and the above chalcogenides, preferably contain at least one of titanium and lithium as constituent components. Examples of lithium-containing metal composite oxides (lithium composite metal oxides) include composite oxides of lithium oxide and the above metal (composite) oxide or the above chalcogenide, more specifically Li ２ SnO ２ Examples include: The negative electrode active material, for example, a metal oxide, is also preferably one that contains titanium (titanium oxide). Specifically, Li ４ Ti ５ O １２ Lithium titanate (LTO) is preferable because it exhibits excellent rapid charge-discharge characteristics due to its small volume fluctuation during lithium ion intercalation and deintercalation, which suppresses electrode degradation and improves the lifespan of lithium-ion secondary batteries.

[0158] The lithium alloy used as the negative electrode active material is not particularly limited as long as it is an alloy that is commonly used as the negative electrode active material for secondary batteries. For example, lithium aluminum alloy, specifically a lithium aluminum alloy in which lithium is the base metal and 10% by mass of aluminum is added, is an example.

[0159] The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is one that is commonly used as a negative electrode active material in secondary batteries. Examples of such active materials include (negative electrode) active materials (alloys, etc.) containing silicon or tin, and metals such as Al and In. Negative electrode active materials containing silicon (silicon-containing active materials) that enable higher battery capacity are preferred, and silicon-containing active materials in which the silicon content is 50 mol% or more of the total constituent elements are more preferred. Generally, negative electrodes containing these negative electrode active materials (for example, Si negative electrodes containing silicon-containing active materials, Sn negative electrodes containing tin-containing active materials, etc.) can absorb more Li ions than carbon negative electrodes (graphite and acetylene black, etc.). That is, the amount of Li ions absorbed per unit mass increases. Therefore, the battery capacity (energy density) can be increased. As a result, there is an advantage in that the battery operating time can be extended. Examples of silicon-containing active materials include Si, SiO ｘ Silicon materials such as (0 < x ≤ 1), and also silicon-containing alloys containing titanium, vanadium, chromium, manganese, nickel, copper, lanthanum, etc. (for example, LaSi ２ , VSi ２ La-Si, Gd-Si, Ni-Si), or organized active material (e.g., LaSi ２ / Si), and also SnSiO ３ SnSiS ３ Examples include active materials containing silicon and tin elements. ｘ It can be used as a negative electrode active material (metallic oxide) itself, and since it generates Si through the operation of an all-solid-state secondary battery, it can be used as a negative electrode active material (its precursor material) that can be alloyed with lithium. Examples of negative electrode active materials containing the tin element include Sn, SnO, and SnO. ２ SnS, SnS ２ Furthermore, active materials containing the above-mentioned silicon and tin elements are also mentioned. Also, composite oxides with lithium oxide, for example, Li ２ SnO ２ One could also list these.

[0160] 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.

[0161] When a negative electrode active material is used as a negative electrode composition, it is preferable that the negative electrode active material be 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 adjusted 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.

[0162] The negative electrode active material contained in the negative electrode active material layer and the negative electrode composition may be one type or two or more types. The content of the negative electrode active material in the negative electrode active material layer and the negative electrode composition is not particularly limited and can be determined as appropriate. For example, in 100% by mass of the solid content of the negative electrode composition or 100% by mass of the negative electrode active material layer, 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.

[0163] 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.

[0164] The surface of the negative electrode active material may be coated with another metal oxide. The surface coating agent described for the positive electrode active material can be used. Furthermore, the electrode surface containing the negative electrode active material may be surface-treated with sulfur or phosphorus. Additionally, the particle surface of the 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.

[0165] <Preferred Embodiment of All-Solid-State Secondary Battery> A preferred embodiment of the all-solid-state secondary battery of the present invention will be described below with reference to Figure 1, but the present invention is not limited thereto.

[0166] Figure 1 is a schematic cross-sectional view showing an all-solid-state secondary battery (lithium-ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 of this embodiment has, when viewed from the negative electrode side, a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in this order. Each layer is in contact with the others and has an adjacent structure. By adopting such a structure, during charging, electrons (e － ) is supplied, and lithium ions (Li ＋ ) accumulates. On the other hand, during discharge, lithium ions (Li) accumulated on the negative electrode ＋ The discharge is returned to the positive electrode side, and electrons are supplied to the working part 6. In the illustrated example, a light bulb is used as a model for the working part 6, and it is designed to light up when the discharge occurs.

[0167] When an all-solid-state secondary battery having the layer configuration shown in Figure 1 is placed in a 2032 type coin case 11 (see, for example, Figure 2), this all-solid-state secondary battery is sometimes referred to as the all-solid-state secondary battery laminate 12, and the battery produced by placing this all-solid-state secondary battery laminate 12 in the 2032 type coin case 11 is sometimes referred to as the (coin-type) all-solid-state secondary battery 13.

[0168] (Positive Electrode Active Material Layer) In the all-solid-state secondary battery 10, the positive electrode active material layer 4 is formed of the electrode composition of the present invention. This positive electrode active material layer 4 contains an inorganic solid electrolyte having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a positive electrode active material, a fibrous conductive additive, a linear polymer, and any of the above-mentioned components, etc., to the extent that they do not impair the effects of the present invention. The inorganic solid electrolyte, positive electrode active material, fibrous conductive additive, and linear polymer contained in the positive electrode active material layer 4 may be the same or different from the components contained in the solid electrolyte layer or the negative electrode active material layer, respectively.

[0169] (Solid electrolyte layer, negative electrode active material layer) In the all-solid-state secondary battery 10, the solid electrolyte layer 3 and the negative electrode active material layer 2 are formed from known materials, preferably as described above.

[0170] (Current Collectors) The positive electrode current collector 5 and the negative electrode current collector 1 are as described above. In the all-solid-state secondary battery 10, each layer may be composed of a single layer or multiple layers.

[0171] [Manufacturing of All-Solid-State Secondary Batteries] The all-solid-state secondary battery of the present invention can be manufactured by conventional methods using the electrode composition of the present invention. For example, the all-solid-state secondary battery can be manufactured by forming a positive electrode active material layer using the electrode composition of the present invention. Specifically, the all-solid-state secondary battery of the present invention can be manufactured by a method (method for manufacturing an electrode sheet for an all-solid-state secondary battery of the present invention) that includes a step of applying the electrode composition of the present invention to a substrate (for example, a metal foil that will serve as a current collector) to form a coating film (film formation). More specifically, the electrode composition of the present invention is applied and dried on a metal foil that serves as a positive electrode current collector to form a positive electrode active material layer and produce a positive electrode sheet for an all-solid-state secondary battery. Next, an all-solid-state secondary battery composition (inorganic solid electrolyte-containing composition) for forming a solid electrolyte layer is applied and dried on this positive electrode active material layer to form a solid electrolyte layer. Furthermore, an all-solid-state secondary battery composition containing a negative electrode active material is applied and dried on the solid electrolyte layer to form a negative electrode active material layer. By layering a negative electrode current collector (metal foil) on top of a 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 then be enclosed in a housing to create a desired all-solid-state secondary battery. Alternatively, by reversing the formation method of each layer, an all-solid-state secondary battery can be manufactured by forming the negative electrode active material layer, solid electrolyte layer, and positive electrode active material layer on top of the negative electrode current collector, and then stacking the positive electrode current collector on top.

[0172] Another method is as follows: A positive electrode sheet for an all-solid-state secondary battery is prepared as described above. A composition for an all-solid-state secondary battery containing a negative electrode active material is applied and dried onto a metal foil, which is the negative electrode current collector, to form a negative electrode active material layer and prepare an all-solid-state secondary battery negative electrode sheet. Next, a solid electrolyte layer is formed on the active material layer of either of these sheets as described above. Furthermore, the other of the positive electrode sheet and the negative electrode sheet for an all-solid-state secondary battery is laminated on the solid electrolyte layer so that the solid electrolyte layer and the active material layer are in contact. In this way, an all-solid-state secondary battery can be manufactured. Yet another method is as follows: A positive electrode sheet and a negative electrode sheet for an all-solid-state secondary battery are prepared as described above. Separately, a composition for an all-solid-state secondary battery is applied and dried onto a substrate to prepare a solid electrolyte sheet for an all-solid-state secondary battery consisting of a solid electrolyte layer. Furthermore, the solid electrolyte layer peeled from the substrate is laminated between a positive electrode sheet and a negative electrode sheet for an all-solid-state secondary battery. In this way, an all-solid-state secondary battery can be manufactured.

[0173] Furthermore, a positive electrode sheet or negative electrode sheet for an all-solid-state secondary battery, and a solid electrolyte sheet for an all-solid-state secondary battery are manufactured as described above. Next, the positive electrode sheet or negative electrode sheet for an all-solid-state secondary battery and the solid electrolyte sheet for an all-solid-state secondary battery are stacked on top of each other with the positive electrode active material layer or negative electrode active material layer and the solid electrolyte layer in contact, and then pressurized. In this way, the solid electrolyte layer is transferred to the positive electrode sheet or negative electrode sheet for an all-solid-state secondary battery. After that, the solid electrolyte layer from which the substrate of the solid electrolyte sheet for an all-solid-state secondary battery has been peeled off is stacked on top of the negative electrode sheet or positive electrode sheet for an all-solid-state secondary battery (with the negative electrode active material layer or positive electrode active material layer in contact with the solid electrolyte layer), and pressurized. In this way, an all-solid-state secondary battery can be manufactured. The pressurizing method and pressurizing conditions in this method are not particularly limited, and the methods and pressurizing conditions described in the pressurizing process described later can be applied.

[0174] The positive electrode active material layer, etc., can also be formed, for example, by pressurizing a composition for all-solid-state secondary batteries, etc., on a substrate or active material layer under the pressurized conditions described later. In the above manufacturing method, the electrode composition of the present invention is used as the positive electrode composition. When forming the solid electrolyte layer and the negative electrode active material layer, commonly used compositions, etc., can be used as materials. Furthermore, instead of forming the negative electrode active material layer during the manufacture of the all-solid-state secondary battery, the negative electrode active material layer can also be formed by bonding ions of metals belonging to Group 1 or Group 2 of the periodic table, which have accumulated on the negative electrode current collector during initialization or charging during use, etc., with electrons and depositing them as metal on the negative electrode current collector, etc.

[0175] <Formation of Each Layer (Film Formation)> The method of coating the electrode composition of the present invention and known materials is not particularly limited and can be appropriately selected. For example, coating methods (preferably wet coating) include spray coating, spin coating, dip coating, slit coating, stripe coating, bar coating, etc. The coating temperature is not particularly limited and is usually in a temperature range of about room temperature (e.g., 15 to 30°C) without heating. The coated electrode composition of the present invention, etc., is subjected to a drying treatment (heat treatment). The drying treatment may be performed after coating the composition, or after coating multiple compositions in layers. The drying temperature is not particularly limited. The lower limit is preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. The upper limit is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. By heating in such a temperature range, the dispersion medium can be removed and the material can be made into a solid state (coated dried layer). It is also preferable because the temperature is not raised too high and the individual components of the all-solid-state secondary battery are not damaged. As a result, all-solid-state secondary batteries exhibit excellent battery performance, good bonding properties, and good ionic conductivity. The drying time of the coated electrode composition of the present invention is appropriately determined according to the amount coated, the area coated, etc., but in the case of the highly concentrated electrode composition of the present invention as described above, it can be dried in a short time, for example, 10 minutes or less.

[0176] <Formation of Each Layer (Film Formation)> After coating and drying the electrode composition of the present invention, it is preferable to pressurize each layer or the all-solid-state secondary battery after stacking the constituent layers or after manufacturing the all-solid-state secondary battery. It is also preferable to pressurize the layers in a stacked state. Examples of pressurizing methods include hydraulic cylinder presses. The pressurizing pressure is not particularly limited, but is generally preferably in the range of 5 to 1500 MPa. The coated electrode composition of the present invention may also be heated at the same time as pressurizing. The heating temperature is not particularly limited, but is generally in the range of 30 to 300°C. It is also possible to press at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. It is also possible to press at a temperature higher than the glass transition temperature of the linear polymer. However, it is generally a temperature that does not exceed the melting point of the linear polymer. Pressurizing may be performed with the coating solvent or dispersion medium pre-dried, or with residual solvent or dispersion medium. The electrode composition of the present invention may be coated simultaneously, or the coating, drying, and pressing may be performed simultaneously and / or sequentially. It may also be coated onto separate substrates and then laminated by transfer.

[0177] The atmosphere used in the film formation method (coating, drying, and (heated) pressurization) is not particularly limited and may be air, dry air (dew point below -20°C), or an inert gas (e.g., argon, helium, nitrogen). The pressing time may be short (e.g., within a few hours) with high pressure, or long (more than a day) with moderate pressure. For applications other than electrode sheets for all-solid-state secondary batteries, such as all-solid-state secondary batteries, a restraint device for the all-solid-state secondary battery (e.g., screw tightening pressure) may be used to maintain moderate pressure. The pressing pressure may be uniform or varied across the pressed area, such as the sheet surface. The pressing pressure can be varied according to the area or film thickness of the pressed area. The same area may also be subjected to different pressures in stages. The pressed surface may be smooth or roughened.

[0178] In the manufacture of electrode sheets for all-solid-state secondary batteries and all-solid-state secondary batteries, using the highly concentrated electrode composition of the present invention allows for a shorter drying time after coating and reduces the amount of volatilization of the dispersion medium. As a result, productivity can be improved, environmental impact reduced, and manufacturing costs reduced. Therefore, the electrode composition of the present invention is also beneficial from the viewpoint of industrial manufacturing of electrode sheets for all-solid-state secondary batteries and all-solid-state secondary batteries.

[0179] <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 with increased press pressure, and then releasing the pressure until it reaches the general operating pressure of the all-solid-state secondary battery.

[0180] [Applications of All-Solid-State Rechargeable Batteries] The all-solid-state rechargeable battery of the present invention can be applied to a variety of applications. There are no particular limitations on the application, but for example, when mounted on electronic devices, examples include notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, cordless phone handsets, pagers, handheld terminals, portable fax machines, portable copiers, portable printers, headphone stereos, video cameras, LCD televisions, handheld vacuum cleaners, portable CDs, MiniDiscs, electric shavers, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, and backup power supplies. Other consumer applications include automobiles (electric vehicles, etc.), electric vehicles, motors, lighting fixtures, toys, game consoles, road conditioners, clocks, strobes, cameras, and medical devices (pacemakers, hearing aids, shoulder massagers, etc.). Furthermore, it can be used for various military and space applications. It can also be combined with solar cells.

[0181] The present invention will be described in more detail below based on examples, but the present invention is not to be interpreted as being limited thereto. In the following examples, "parts" and "%" representing composition are on a mass basis unless otherwise specified. In the present invention, "room temperature" means 25°C. In these examples, Tables 1-1 and 1-2 are collectively referred to as "Table 1," Tables 2-1 and 2-2 are collectively referred to as "Table 2," and Tables 3-1 and 3-2 are collectively referred to as "Table 3."

[0182] 1. Synthesis of Linear Polymers The following linear polymers were synthesized from the linear polymers shown in the above specific examples (chemical formulas) as follows.

[0183] [Synthesis Example A-1: ​​Synthesis of Linear Polymer A-1] 100 g of deionized water, 75 g of vinylidene fluoride, and 25 g of hexafluoropropene were added to an autoclave. 1 g of the polymerization initiator perloyl IPP (trade name, chemical name: diisopropyl peroxydicarbonate, manufactured by Nippon Oil & Fats Co., Ltd.) was then 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. In this way, linear polymer A-1 (fluoropolymer) was synthesized.

[0184] [Synthesis Example A-5: Synthesis of Linear Polymer A-5] In a nitrogen-purged and dried pressure vessel, 300 g of cyclohexane was charged as the solvent and 2.0 mL of sec-butyllithium (1.3 M, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the polymerization initiator. After raising the temperature to 50°C, 30 g of styrene was added and polymerization was carried out for 2 hours. Subsequently, 25 g of 1,3-butadiene and 45 g of ethylene were added and polymerization was carried out for 3 hours. The obtained solution was reprecipitated in methanol, and 100 parts by mass of the polymer obtained by drying the solid was added to 3 parts by mass of 2,6-di-t-butyl-p-cresol, and the reaction was carried out at 180°C for 5 hours. The obtained solution was reprecipitated in acetonitrile, and the obtained 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 then vacuum dried. In this way, linear polymer A-5 (hydrocarbon polymer) was synthesized.

[0185] [Synthesis Example A-6: Synthesis of Linear Polymer A-6] Linear polymer A-6 (hydrocarbon polymer) was synthesized in the same manner as in Synthesis Example A-5, except that compounds were used to derive each component to achieve the structure shown in the above chemical formula, and the amount of polymerization initiator was appropriately changed to adjust the molecular weight.

[0186] [Synthesis Example A-7: Synthesis of Linear Polymer A-7] In a nitrogen-purged and dried pressure vessel, 300 g of cyclohexane was charged as the solvent and 2.0 mL of sec-butyllithium (1.3 M, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the polymerization initiator. After raising the temperature to 50°C, 30 g of styrene, 25 g of 1,3-butadiene, 1 g of maleic anhydride, and 44 g of ethylene were added and polymerization was carried out for 5 hours. The obtained solution was reprecipitated in methanol, and 100 parts by mass of the polymer obtained by drying the solid was added to 3 parts by mass of 2,6-di-t-butyl-p-cresol, and the reaction was carried out at 180°C for 5 hours. The obtained solution was reprecipitated in acetonitrile, and the obtained 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 then vacuum-dried to synthesize linear polymer A-7 (hydrocarbon polymer).

[0187] [Synthesis Example A-8: Synthesis of Linear Polymer A-8] Linear polymer A-8 (hydrocarbon polymer) was synthesized in the same manner as in Synthesis Example A-7, except that compounds were used to derive each component to achieve the structure shown in the above chemical formula, and the amount of polymerization initiator was appropriately changed to adjust the molecular weight.

[0188] [Synthesis Example A-9: Synthesis of Linear Polymer A-9] Linear polymer A-9 (hydrocarbon polymer) was synthesized in the same manner as in Synthesis Example A-7, except that compounds were used to derive each component to achieve the structure shown in the above chemical formula, and the amount of polymerization initiator was appropriately changed to adjust the molecular weight.

[0189] [Synthesis Example A-10: Synthesis of Linear Polymer A-10] In a nitrogen-purged and dried pressure vessel, 300 g of cyclohexane was charged as the solvent and 1.7 mL of sec-butyllithium (1.3 M, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the polymerization initiator. After raising the temperature to 50°C, 30 g of styrene, 25 g of 1,3-butadiene, 1 g of maleic anhydride, and 44 g of ethylene were added and polymerization was carried out for 5 hours. To 100 parts by mass of the polymer obtained by drying the resulting solid, 3 parts by mass of 2,6-di-t-butyl-p-cresol were 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 synthesize linear polymer A-10 (hydrocarbon polymer).

[0190] [Synthesis Example A-11: Synthesis of Linear Polymer A-11] 50 g of butyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 50 g of styrene (manufactured by Tokyo Chemical Industry Co., Ltd.), and 4.0 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a 200 mL volumetric flask and dissolved in 70 g of diisobutyl ketone (DIBK) to prepare a monomer solution. Next, 40 g of DIBK was added to a 500 mL three-necked flask and stirred at 80°C under a nitrogen stream. The monomer solution was then added dropwise over 2 hours. After the dropwise addition was complete, the temperature was raised to 90°C and stirred for 2 hours. The resulting polymerization solution was poured into 800 g of methanol, stirred for 10 minutes, and then allowed to stand for 10 minutes. After removing the supernatant, the resulting precipitate was dissolved in 60 g of butyl butyrate and the methanol was removed by distillation by heating at 30 hPa and 80°C for 1 hour. In this way, linear polymer A-11 (vinyl polymer) was synthesized.

[0191] [Synthesis Example A-13: Synthesis of Linear Polymer A-13] 35 g of dodecyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 65 g of styrene (manufactured by Tokyo Chemical Industry Co., Ltd.), and 3.9 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Corporation) were added to a 200 mL volumetric flask and dissolved in 70 g of DIBK to prepare a monomer solution. Next, 40 g of DIBK was added to a 500 mL three-necked flask, stirred at 80 °C under a nitrogen stream, and the above monomer solution was added dropwise over 2 hours. After completion of the dropwise addition, the temperature was raised to 90 °C and stirred for 2 hours. The obtained polymerization solution was poured into 800 g of methanol, stirred for 10 minutes, and then allowed to stand for 10 minutes. The precipitate obtained after removing the supernatant was dissolved in 60 g of butyl butyrate, and methanol was distilled off by heating at 30 hPa and 80 °C for 1 hour. In this way, linear polymer A-13 (vinyl polymer) was synthesized.

[0192] [Synthesis Example A-14: Synthesis of Linear Polymer A-14] In Synthesis Example A-11, a linear polymer A-14 (vinyl polymer) was synthesized in the same manner as in Synthesis Example A-11, except that compounds leading to each constituent were used so that the structure shown in the above chemical formula was obtained, and the amount of the polymerization initiator was appropriately changed to adjust the molecular weight.

[0193] [Synthesis Example A-16: Synthesis of Linear Polymer A-16] 90 g of octadecyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 9.5 g of 2-ethylhexyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.5 g of maleic anhydride, and 3.6 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Corporation) were added to a 200 mL volumetric flask and dissolved in 70 g of diisobutyl ketone (DIBK) to prepare a monomer solution. Next, 40 g of DIBK was added to a 500 mL three-necked flask, stirred at 80 °C under a nitrogen stream, and the above monomer solution was added dropwise over 2 hours. After completion of the dropwise addition, the temperature was raised to 90 °C and stirred for 2 hours. The obtained polymerization solution was poured into 800 g of methanol, stirred for 10 minutes, and then allowed to stand for 10 minutes. The precipitate obtained after removing the supernatant was dissolved in 60 g of butyl butyrate, and methanol was distilled off by heating at 30 hPa and 80 °C for 1 hour. Thus, linear polymer A-16 ((meth)acrylic polymer) was synthesized.

[0194] [Synthesis Examples A-17, A-18, and A-21: Synthesis of Linear Polymers A-17, A-18, and A-21] In Synthesis Example A-16, linear polymers A-17, A-18, and A-21 ((meth)acrylic polymers) were synthesized in the same manner as in Synthesis Example A-16, except that compounds that lead to the structures shown in the above chemical formula were used and the amount of the polymerization initiator was appropriately changed to adjust the molecular weight.

[0195] [Synthesis Example A-20: Synthesis of Linear Polymer A-20] In a 200 mL volumetric flask, 95 g of dodecyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 5 g of 2-hydroxyethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.9 g of polymerization initiator V-601 (trade name, manufactured by Fuji Film Wako Pure Chemical Corporation) were added and dissolved in 70 g of DIBK to prepare a monomer solution. Next, 40 g of DIBK was added to a 500 mL three-necked flask, and the mixture was stirred at 80°C under a nitrogen stream. Then, the above monomer solution was added dropwise over 2 hours. After the dropwise addition was completed, the temperature was raised to 90°C and stirred for 2 hours. Thus, linear polymer A-20 ((meth)acrylic polymer) was synthesized.

[0196] [Synthesis Example A-22: Synthesis of Linear Polymer A-22] In Synthesis Example A-20, linear polymer A-22 ((meth)acrylic polymer) was synthesized in the same manner as in Synthesis Example A-20, except that the amount of the polymerization initiator was appropriately changed to adjust the molecular weight.

[0197] [Synthesis Examples A-25 to A-27, A-29, and A-30: Synthesis of Linear Polymers A-25 to A-27, A-29, and A-30] In Synthesis Example A-20, linear polymers A-25 to A-27, A-29, and A-30 ((meth)acrylic polymers) were synthesized in the same manner as in Synthesis Example A-20, except that compounds that lead to the structures shown in the above chemical formula were used and the amount of the polymerization initiator was appropriately changed to adjust the molecular weight.

[0198] The polymers shown in the following chemical formula were synthesized as follows. In the following chemical formula, the numbers described at the lower right of each constituent component indicate the content (mass%).

[0199]

[0200] [Synthesis Examples B-1 and B-2: Synthesis of Polymers B-1 and B-2] Polymers B-1 and B-2 (hydrocarbon polymers) were synthesized in the same manner as in Synthesis Example A-5, except that compounds were used to derive each component to achieve the structure shown in the above chemical formula, and the amount of polymerization initiator was appropriately changed to adjust the molecular weight.

[0201] [Synthesis Example B-3: Synthesis of Polymer B-3] Polymer B-3 ((meth)acrylic polymer) was synthesized in the same manner as in Synthesis Example A-20, except that compounds were used to derive each component so that the structure shown in the above chemical formula was obtained, and the amount of polymerization initiator was appropriately changed to adjust the molecular weight.

[0202] [Synthesis Example B-4: Synthesis of Polymer B-4] B-4 (vinyl polymer) was synthesized in the same manner as in Synthesis Example A-11, except that compounds were used to derive each component to achieve the structure shown in the above chemical formula, and the amount of polymerization initiator was appropriately changed to adjust the molecular weight.

[0203] [Synthesis Example C-1: Synthesis of Polymer C-1] In a 500 mL graduated cylinder, 200 g of styrene, 10.0 g of 3-mercaptopropionic acid, and 4.0 g 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 1 L three-necked flask, 230 g 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, 180 mg of 2,2,6,6-tetramethylpiperidine-1-oxyl (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 17.5 g of glycidyl methacrylate (manufactured by Tokyo Chemical Industries, Ltd.), and 3.5 g 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 1000 g of methanol, and the supernatant was removed. Butyl butyrate was added, and the methanol was removed under reduced pressure to obtain a butyl butyrate solution of macromonomer M-1 (number average molecular weight 9000). The solid content concentration was 50% by mass. In a 100 mL graduated cylinder, 20.0 g of hexyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1.0 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in 30.0 g of butyl butyrate to prepare a monomer solution. In a 300 mL three-necked flask, 40.0 g of macromonomer M-1 solution and 36.0 g of butyl butyrate were added and stirred at 80°C, and the above 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. The obtained polymerization solution was poured into 1000 g of methanol, stirred for 10 minutes, and then allowed to stand for 10 minutes. After removing the supernatant, the resulting precipitate was dissolved in 60 g of butyl butyrate and methanol was removed by distillation by heating at 30 hPa and 80°C for 1 hour. Graft polymer C-1 ((meth)acrylic polymer) was synthesized in this manner.

[0204] [Synthesis Examples C-2 and C-3: Synthesis of Polymers C-2 and C-3] Graft polymers C-2 and C-3 ((meth)acrylic polymers) were synthesized in the same manner as in Synthesis Example C-1, except that compounds were used to derive each component to achieve the structure shown in the above chemical formula, and the amount of polymerization initiator was appropriately changed to adjust the molecular weight.

[0205] [Preparation of SBR] The following styrene-butadiene rubber was prepared: SBR: Styrene-butadiene rubber, manufactured by Aldrich.

[0206] 2. Synthesis of Sulfide-Based Inorganic Solid Electrolytes <Synthesis Example A> Sulfide-based inorganic solid electrolytes were synthesized with reference to the non-patent literature of T. Ohtomo, A. Hayashi, M. Tatsumisago, Y. Tsuchida, S. Hama, K. Kawamoto, Journal of Power Sources, 233, (2013), pp. 231-235, and A. Hayashi, S. Hama, H. Morimoto, M. Tatsumisago, T. Minami, Chem. Lett., (2001), pp. 872-873. Specifically, in a glove box under an argon atmosphere (dew point -70°C), lithium sulfide (Li ２ S, Aldrich, purity >99.98%, 2.42g and phosphorus pentasulfide (P ２ S ５ 3.90 g each of Aldrich (purity >99%) was weighed out and placed in an agate mortar, and mixed for 5 minutes using an agate pestle. ２ S and P ２ S ５ The mixing ratio is Li in molar ratio. ２ S:P ２ S ５The ratio was set to 75:25. 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 was performed at a temperature of 25°C and a rotation speed of 510 rpm for 20 hours to obtain 6.20 g of yellow powder sulfide-based inorganic solid electrolyte (Li-P-S glass, hereinafter sometimes referred to as LPS). The particle size of the Li-P-S glass was 15 μm.

[0207] 3. Preparation of Fibrous Conductive Additives The following fibrous conductive additives 1 to 3 were prepared. Fibrous conductive additive 1: Vapor-grown carbon fiber (product name: VGCF-H, manufactured by Resonaq, average minor axis diameter 0.15 μm, average major axis length 4.8 μm, ratio [average major axis length / average minor axis diameter] 32) Fibrous conductive additive 2: Single-walled carbon nanotube (product name: TUBALL, manufactured by OCSiAl, average minor axis diameter 2 nm, average major axis length 0.8 μm, ratio [average major axis length / average minor axis diameter] 400) Fibrous conductive additive 3: Multi-walled carbon nanotube (manufactured by Sigma-Aldrich, average minor axis diameter 0.01 μm, average major axis length 12 μm, ratio [average major axis length / average minor axis diameter] 1200)

[0208] For each fibrous conductive additive, the average minor axis diameter and average major axis length were measured as follows, and the ratio [average major axis length / average minor axis diameter] was calculated from the measured values. Specifically, a dispersion of the fibrous conductive additive in a 1% by mass sodium dodecylsulfonate aqueous solution was scanned using a scanning electron microscope (SEM) at 5000 to 20000x magnification to acquire 10 fields of view. For the minor axis diameter, five fiber bundles were selected from one field of view of the obtained SEM image, and the width of each fiber bundle was measured at three points, and the average value (arithmetic mean) of these measurements was taken. For the major axis length, the arithmetic mean of the axial lengths of both ends of five fibers in one field of view of the obtained SEM image was taken.

[0209] <Measurement of Weight-Average Molecular Weight> The weight-average molecular weight of each prepared polymer was measured using the method described above. The results are shown in Tables 1 to 3.

[0210] <Adsorption rate A ＦＡMeasurement of the adsorption rate of polymers to fibrous conductive additives A ＦＡ The percentage (%) was measured using the fibrous conductive additive, polymer, and dispersion medium used in the preparation of the electrode compositions in each example and comparative example, as follows: 0.6 g of each polymer was dissolved in 9.4 g of butyl butyrate to prepare 10 g of each polymer solution with a solid content of 6% by mass. Next, 10 g of each prepared polymer solution, 0.3 g of fibrous conductive additive, and 10 g of butyl butyrate were added to a 60 mL ointment container and stirred in a rotary-orbit mixer at 2000 rpm rotation and 800 rpm revolution for 10 minutes. Each resulting mixture (solid content concentration 3% by mass) was filtered using a membrane filter with a pore size of 0.2 μm (a pore size that the fibrous conductive additive could not pass through). The mass of the filtrate was measured and designated as W1 (g). Next, the entire volume of the filtrate was dried at 120°C for 3 hours, and the mass of the polymer remaining in the filtrate (the mass of the polymer that was not adsorbed by the fibrous conductive additive) was measured and designated as W2 (g). The solid content X of each polymer solution in the filtrate was determined by W2 / W1 × 100 (%), and the adsorption rate of each polymer to the fibrous conductive additive was calculated using the following formula. The average of the adsorption rates obtained by performing this measurement twice for each polymer was used to determine the adsorption rate A of the polymer to the fibrous conductive additive in each example and comparative example. ＦＡ The results are shown in Tables 1 to 3. Adsorption rate A ＦＡ (%)=[(3-X) / 3]×100

[0211] <Evaluation of Polymer Solubility> The solubility of the polymer in each composition described later (condition (1)) was measured in the dispersion medium using the method described above. As a result, if the solubility was 80% or higher, the polymer was considered to dissolve in the dispersion medium and was indicated as "dissolved" in the "Form" column of Tables 1 to 3. If the solubility was less than 80%, the polymer did not dissolve in the dispersion medium and was dispersed as particulate matter and was indicated as "particles" in the "Form" column of Tables 1 to 3.

[0212] [Example 1 and Comparative Example 1] <Example 1-1> In a container, 8.0 g of NCM-1 as the positive electrode active material, 1.6 g of LPS synthesized in Synthesis Example A as the inorganic solid electrolyte, 0.3 g of VGCF-H (trade name) as a fibrous conductive additive, 0.1 g of linear polymer A-1 shown in the "Polymer" column of Table 1, and 3.15 g of butyl butyrate were added and mixed for 15 minutes using a rotary-revolving mixer at 2000 rpm rotation and 800 rpm revolution to obtain positive electrode composition 1-1 (solid content concentration 76% by mass). The prepared cathode composition 1-1 was applied onto a 20 μm thick aluminum foil using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.), heated at 120°C for 1 hour, and then dried in a vacuum dryer AVO-200NS (product name, manufactured by AS ONE Corporation) at 120°C for 2 hours to dry the cathode composition 1-1 (remove the dispersion medium). Thus, the amount of the mixture was 20 mg / cm³. ２ A positive electrode sheet 1-1 for an all-solid-state secondary battery having a positive electrode active material layer was fabricated. Here, the amount of composite material refers to the total mass of the inorganic solid electrolyte, positive electrode active material, and fibrous conductive additive per unit area.

[0213] Using the fabricated positive electrode sheet 1-1 for all-solid-state secondary batteries, an all-solid-state secondary battery 1-1 was constructed as follows: The positive electrode sheet 1-1 for all-solid-state secondary batteries was punched out into a disc shape with a diameter of 10 mmφ and placed in a 10 mmφ polyethylene terephthalate (PET) cylinder. 60 mg of LPS synthesized in the above synthesis example A was placed on the surface of the positive electrode active material layer inside the cylinder, and 10 mmφ stainless steel rods were inserted from the openings at both ends of the cylinder. The positive electrode current collector side of the positive electrode sheet for all-solid-state secondary batteries and the LPS were pressurized and formed using the stainless steel rods at a pressure of 350 MPa to form a solid electrolyte layer. Subsequently, the stainless steel rods placed on the solid electrolyte layer side were removed, and a 9 mmφ disc-shaped indium (In) sheet (thickness 20 μm) and a 9 mmφ disc-shaped lithium (Li) sheet (thickness 20 μm) were inserted in this order onto the solid electrolyte layer inside the cylinder. The SUS rod that had been removed was reinserted into the cylinder and fixed in place under a pressure of 50 MPa. In this way, an all-solid-state secondary battery (half-cell) 1-1 was manufactured, having the following configuration: aluminum foil (thickness 20 μm) - positive electrode active material layer (thickness 100 μm) - solid electrolyte layer (thickness 200 μm) - negative electrode active material layer (In / Li sheet, thickness 30 μm).

[0214] <Examples 1-2 to 1-9 and Comparative Examples c1-1 to c1-6> Cathode compositions 1-2 to 1-9 and c1-1 to c1-6 were prepared in the same manner as in Example 1-1, except that the polymer shown in the "Polymer" column of Table 1 was used instead of the linear polymer A-1, and the solid content concentration was appropriately changed to the value shown in the "Solid Content Concentration" column of Table 1. Next, all-solid-state secondary battery cathode sheets 1-2 to 1-9 and c1-1 to c1-6 were prepared in the same manner as in Example 1-1, except that the cathode compositions 1-2 to 1-9 and c1-1 to c1-6 were used instead of the cathode composition 1-1 in Example 1-1, and all-solid-state secondary batteries 1-2 to 1-9 and c1-1 to c1-6 were manufactured.

[0215] <Evaluation 1: Evaluation of the drying rate of the positive electrode active material layer> Each obtained positive electrode composition was coated onto a 20 μm thick aluminum foil using a 300 μm master blade, and dried on a hot plate at 40°C for 60 minutes to prepare test positive electrode sheets. The mass of a positive electrode piece P1 cut out from each positive electrode sheet to a 30 × 30 mm square was measured and designated as the 40°C positive electrode mass. Next, the positive electrode piece P1 was heated and dried in a vacuum dryer AVO-200NS (product name, manufactured by AS ONE Corporation) at 120°C for 2 hours, and its mass was measured and designated as the 120°C positive electrode mass. For evaluation, the mass ratio (%) of the 40°C positive electrode mass to the 120°C positive electrode mass was calculated, and if this mass ratio satisfied the following formula (if it was 105% or more), it was judged that positive electrode production was impossible. If positive electrode production was impossible, it was marked with "×", and if positive electrode production was possible, it was marked with "○", and this is shown in the "Drying Rate" column of Table 1. This evaluation (test) is for reference purposes only. Evaluation criteria: (40°C positive electrode mass / 120°C positive electrode mass) × 100 ≥ 105

[0216] <Evaluation 2: Evaluation of Surface Roughness of the Positive Electrode Active Material Layer> Each of the obtained positive electrode compositions was coated onto a 20 μm thick aluminum foil using a 200 μm master blade, and dried on a hot plate at 120°C for 30 minutes to prepare test positive electrode sheets. The average height Rc (Japanese Industrial Standard (JIS) B 0601:2013) of the roughness curve elements of each positive electrode sheet was measured using a roughness meter. For evaluation, if the average height Rc was 10 μm or more, it was judged that positive electrode production was impossible. Cases where positive electrode production was impossible were marked with "×", and cases where positive electrode production was possible were marked with "○", as shown in the "Average Height Rc" column of Table 1. This evaluation (test) is a reference evaluation (test).

[0217] <Evaluation 3: Evaluation of the state of presence (aggregates) of fibrous conductive additive in the positive electrode active material layer> A cross-section was formed for each positive electrode sheet for all-solid-state secondary batteries that was fabricated, using a cross-section polisher (manufactured by JEOL). The conditions for the cross-section polisher were: gas used: argon, acceleration voltage: 1.5 kV, 8 hours. This cross-section was observed with a scanning electron microscope (SEM) at a magnification of 2000x to obtain an SEM image. In the SEM image, the boundaries of the fibrous conductive additive particles could be identified by binarization with KID in ImageJ. Aggregates of fibrous conductive additive larger than 1 μm in a 0.1 mm × 0.05 mm area of ​​this SEM image were identified, and their area ratio was calculated. In Examples 1-1 to 1-9 and Comparative Examples c1-1 to c1-6, the area ratio of the fibrous conductive additive in Comparative Example c1-1 was 9%, and this area ratio of the fibrous conductive additive was used as the standard for evaluation based on the evaluation levels below. In this test, a score of "C" or higher is considered a pass. The results are shown in the "Agglutinations" column of Table 1. - Evaluation Criteria - A: Area ratio is 5% or less below the standard area ratio (5% or more smaller) B: Area ratio is 3% or more but less than 5% below the standard area ratio (3% or more but less than 5% smaller) C: Area ratio is 1% or more but less than 3% below the standard area ratio (1% or more but less than 3% smaller) D: Area ratio is the same as the standard area ratio and is less than 1% but 1% or more above (less than 1% smaller or 1% or less larger) E: Area ratio is 1% or more above the standard area ratio (1% or more larger)

[0218] <Evaluation 4: Evaluation of High-Temperature Load Characteristics> For each manufactured all-solid-state secondary battery, a rate characteristic test was performed using the charge / discharge evaluation device TOSCAT-3000 (product name, manufactured by Toyo System Co., Ltd.) to evaluate the high-temperature load characteristics. Specifically, each all-solid-state secondary battery was subjected to a current density of 1 mA / cm² in an environment of 65°C. ２ The battery was charged until the voltage reached 3.48V. After that, the current density was 1mA / cm². ２ The battery was discharged until the voltage reached 1.88V. After that, the current density was restored to 1mA / cm². ２ After charging until the battery voltage reaches 3.48V, the current density is 5mA / cm². ２The battery was discharged until the voltage reached 1.88V. The rate characteristics were determined using the following formula, and the high-temperature load characteristics (high-temperature rate characteristics) of the all-solid-state secondary battery were evaluated by applying them to the evaluation criteria below. In Examples 1-1 to 1-9 and Comparative Examples c1-1 to c1-6, the high-temperature rate characteristics of Comparative Example c1-1 were 66%, and this high-temperature rate characteristic was used as the standard for evaluation based on the evaluation levels below. In this test, "C" or higher is considered a pass. The results are shown in the "High-Temperature Load" column of Table 1. High-Temperature Rate Characteristics (%) = ((5mA / cm) ２ Discharge capacity at (1 mA / cm²) / (1 mA / cm²) ２ Discharge capacity (at) × 100 - Evaluation criteria - A: Above standard + 15% ≤ High temperature rate characteristics B: Above standard + 10% ≤ High temperature rate characteristics < Above standard + 15% C: Above standard + 5% ≤ High temperature rate characteristics < Above standard + 10% D: Above standard - 5% ≤ High temperature rate characteristics < Above standard + 5% E: High temperature rate characteristics < Above standard - 5%

[0219] <Evaluation 5: High-Temperature Life Evaluation> For each all-solid-state secondary battery manufactured, a rate characteristic test was performed using the charge / discharge evaluation device TOSCAT-3000 (product name, manufactured by Toyo System Co., Ltd.) to evaluate its high-temperature life. Specifically, each all-solid-state secondary battery was tested at a current density of 1 mA / cm² in an environment of 65°C. ２ Charge the battery until the voltage reaches 3.48V, then set the current density to 1mA / cm². ２One cycle was defined as discharging the battery until the voltage reached 1.88V, and this was performed 100 times. The capacity ratio (%) of the discharge capacity in the first cycle to the discharge capacity in the 100th cycle was calculated using the following formula, and the high-temperature life of the all-solid-state secondary battery was evaluated by applying it to the evaluation criteria below. In Examples 1-1 to 1-9 and Comparative Examples c1-1 to c1-6, the capacity ratio of Comparative Example c1-1 was 61%, and this capacity ratio was used as the standard for evaluation based on the evaluation levels below. In this test, a rating of "C" or higher is considered a pass. The results are shown in the "High-Temperature Life" column of Table 1. Capacity Ratio (%) = ((Discharge Capacity at 100 Cycles) / (Discharge Capacity at 1 Cycle)) × 100 - Evaluation Criteria - A: Above Criteria + 10% ≤ Capacity Ratio B: Above Criteria + 7% ≤ Capacity Ratio < Above Criteria + 10% C: Above Criteria + 4% ≤ Capacity Ratio < Above Criteria + 7% D: Above Criteria - 5% ≤ Capacity Ratio < Above Criteria + 4% E: Capacity Ratio < Above Criteria - 5%

[0220]

[0221]

[0222] <Explanation of symbols> NCM-1: LiNi ０．５ Co ０．２ Mn ０．３ O ２ (NCM523), Particle size (volume average particle size) 5 μm as measured by the above method LPS: Li-P-S glass synthesized in synthesis example A above BB: Butyl butyrate (CAS 109-21-7) Note that the weight-average molecular weight of the polymers shown in Table 1 should be given to two significant figures.

[0223] [Example 2 and Comparative Example 2] <Examples 2-1 to 2-6 and Comparative Examples c2-1 to c2-5> In Example 1-1, instead of the linear polymer, the positive electrode active material NCM-1, the fibrous conductive aid 1, and butyl butyrate, the polymer shown in the "Polymer" column of Table 2, NCM-2 as the positive electrode active material, the fibrous conductive aid 2, and xylene as the dispersion medium were mixed at the mass ratios shown in the respective "Mixing Amount" columns of Table 2 and the values shown in the "Solid Content Concentration" column of Table 2. Positive electrode compositions 2-1 to 2-6 and c2-1 to c2-5 were prepared in the same manner as in Example 1-1, except for this. Next, in Example 1-1, positive electrode sheets 2-1 to 2-6 and c2-1 to c2-5 for all-solid-state secondary batteries were produced in the same manner as in Example 1-1, except that positive electrode compositions 2-1 to 2-6 and c2-1 to c2-5 were used instead of positive electrode composition 1-1, and all-solid-state secondary batteries 2-1 to 2-6 and c2-1 to c2-5 were manufactured respectively.

[0224] <Evaluations 1 to 5>For each positive electrode composition prepared in Example 2 and Comparative Example 2, the positive electrode sheet for all-solid-state secondary batteries produced, and the all-solid-state secondary battery manufactured, evaluations were carried out in the same manner as Evaluations 1 to 5 of Example 1, and the results are shown in Table 2. However, the criteria for each of Evaluations 3 to 5 were as follows. In Evaluation 3, the area ratio of the fibrous conductive aid in Comparative Example c2-1 was 11%, and the evaluation was based on this area ratio. In Evaluation 4, the high-temperature rate characteristic of Comparative Example c2-1 was 59%, and the evaluation was based on this high-temperature rate characteristic. In Evaluation 5, the capacity ratio of Comparative Example c2-1 was 65%, and the evaluation was based on this capacity ratio.

[0225]

[0226]

[0227] <Explanation of Symbols>NCM-2: LiNi １／３ Co １／３ Mn １／３ O ２(NCM111), Particle size (volume average particle size) 3 μm as measured by the above method. LPS: Li-P-S glass xylene synthesized in the above synthesis example A: Xylene (CAS 1330-20-7). Note that the weight-average molecular weight of the polymers shown in Table 2 should be given to two significant figures.

[0228] [Example 3 and Comparative Example 3] <Examples 3-1 to 3-6 and Comparative Examples c3-1 to c3-5> Cathode compositions 3-1 to 3-6 and c3-1 to c3-5 were prepared in the same manner as in Example 1-1, except that the polymer shown in the "Polymer" column of Table 3, the fibrous conductive additive 1, and butyl butyrate were replaced with the polymer shown in the "Polymer" column of Table 3, the fibrous conductive additive 3, and mesitylene as a dispersion medium, mixed in the mass ratios shown in the "Amount Mixed" column of Table 3 and the values ​​shown in the "Solid Content Concentration" column of Table 3. Next, in the same manner as in Example 1-1, except that positive electrode compositions 3-1 to 3-6 and c3-1 to c3-5 were used instead of positive electrode composition 1-1, all-solid-state secondary battery positive electrode sheets 3-1 to 3-6 and c3-1 to c3-5 were manufactured, and all-solid-state secondary batteries 3-1 to 3-6 and c3-1 to c3-5 were manufactured, respectively.

[0229] <Evaluation 1 to Evaluation 5> The positive electrode compositions prepared in Example 3 and Comparative Example 3, the positive electrode sheets for all-solid-state secondary batteries prepared, and the manufactured all-solid-state secondary batteries were evaluated in the same manner as evaluations 1 to 5 in Example 1. The results are shown in Table 3. However, the criteria for each evaluation from evaluation 3 to evaluation 5 were as follows. In evaluation 3, the area ratio of the fibrous conductive additive in Comparative Example c3-1 was 10%, and this area ratio was used as the basis for evaluation. In evaluation 4, the high-temperature rate characteristic of Comparative Example c3-1 was 52%, and this high-temperature rate characteristic was used as the basis for evaluation. In evaluation 5, the capacity ratio of Comparative Example c3-1 was 50%, and this capacity ratio was used as the basis for evaluation.

[0230]

[0231]

[0232] <Explanation of symbols> NCM-1: LiNi １／３ Co １／３ Mn １／３ O２ NCM523 (average particle size 5 μm) LPS: Li-P-S glass mesitylene synthesized in the above synthesis example A: Mesitylene (CAS 108-67-8) Note that the weight-average molecular weight of the polymers shown in Table 3 should be given to two significant figures.

[0233] The results shown in Tables 1 to 3 indicate the following: Each cathode composition of the comparative examples that did not satisfy at least one of conditions (1) to (5) failed to achieve sufficient performance in terms of aggregate evaluation, high-temperature load, and high-temperature life. Furthermore, they were inferior in either drying speed or average height Rc, and did not show manufacturability. In contrast, each cathode composition of the examples that satisfied conditions (1) to (5) excelled in aggregate evaluation and exhibited sufficient performance in terms of high-temperature load and high-temperature life, even when containing fibrous conductive additives that are prone to aggregation and have poor dispersibility. This is thought to be because each cathode composition of the examples was able to suppress aggregation and re-aggregation of the fibrous conductive additive and disperse it without excessive localization. Needless to say, each cathode composition of the examples also excelled in evaluations 1 to 5 in a normal temperature environment (e.g., around 15 to 40°C). Furthermore, each of the cathode compositions in the examples exhibited excellent drying speed and average height Rc, demonstrating superior manufacturability while also enabling reduced drying time after coating and reduced environmental impact through reduced dispersant evaporation.

[0234] 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.

[0235] This application claims priority based on Japanese Patent Application No. 2024-170688, filed in Japan on 30 September 2024, the contents of which are incorporated herein by reference as part of this specification.

[0236] 1. Negative electrode current collector 2. Negative electrode active material layer 3. Solid electrolyte layer 4. Positive electrode active material layer 5. Positive electrode current collector 6. Working part 10. All-solid-state secondary battery 11. 2032 type coin case 12. Laminate for all-solid-state secondary battery 13. Coin-type all-solid-state secondary battery

Claims

1. An electrode composition comprising an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a positive electrode active material, a fibrous conductive additive, a linear polymer, and a dispersion medium, satisfying the following conditions (1) to (5): (1) The linear polymer is dissolved in the dispersion medium; (2) The weight-average molecular weight of the linear polymer is 3.0 × 10⁻⁶. ３ (3) The average short axis diameter of the fibrous conductive additive is 1 to 300 nm, and the average long axis length is 500 nm to 50 μm. (4) The adsorption rate A of the linear polymer to the fibrous conductive additive in the dispersion medium. ＦＡ (5) The solid content in the electrode composition is greater than 4% and less than or equal to 45%.

2. Adsorption rate A ＦＡ The electrode composition according to claim 1, wherein the amount is greater than 7% and less than or equal to 30%.

3. The electrode composition according to claim 1, wherein the fibrous conductive additive has an average short axis diameter of 1 to 200 nm and an average long axis length of 500 nm to 10 μm.

4. The weight-average molecular weight of the linear polymer is 1.0 × 10⁻⁶ ４ ~7.0 x 10 ５ The electrode composition according to claim 1.

5. The electrode composition according to claim 1, wherein the solid content in the electrode composition is more than 80% by mass.

6. The electrode composition according to claim 1, wherein the linear polymer comprises a component having at least one functional group from the following functional group group (a). <Functional group group (a)> Sulfonic acid group, phosphoric acid group, phosphonic acid group, carboxyl group, hydroxyl group, oxetane group, epoxy group, carboxylic anhydride group, thiol group, ether group, thioether group, thioester group, thiocarbamate group, imino group, amide group, urethane group, urea group, thiourea group, heterocyclic group, aryl group, fluoroalkyl group, siloxane group, carbonate group, amino group, and salts thereof 7. The electrode composition according to claim 1, wherein the linear polymer comprises a component having substituents with 8 or more carbon atoms in its side chains.

8. The electrode composition according to claim 1, wherein the linear polymer comprises a (meth)acrylic polymer.

9. An electrode sheet for an all-solid-state secondary battery having a positive electrode active material layer composed of the electrode composition described in any one of claims 1 to 8.

10. An all-solid-state secondary battery comprising a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order, wherein the positive electrode active material layer is a layer formed using the electrode composition described in any one of claims 1 to 8.

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 8.

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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