Composition, all-solid-state secondary battery, sheet, and manufacturing method for the latter two

Abstract

This invention provides a composition containing an inorganic solid electrolyte, a sheet for an all-solid-state secondary battery using the inorganic solid electrolyte composition, an all-solid-state secondary battery, and a method for manufacturing the sheet for an all-solid-state secondary battery and the all-solid-state secondary battery. The inorganic solid electrolyte composition is an inorganic solid electrolyte composition for an all-solid-state secondary battery containing an inorganic solid electrolyte, a dispersant, and a dispersion medium. The dispersant satisfies the requirements of (1) to (3) below, and the dispersion medium includes a dispersion medium with a boiling point of 120°C or higher. (1) The SP value is 17.0 to 22.0 MPa. 1 / 2 (2) The molecular weight is below 10,000, and (3) The adsorption rate of inorganic solid electrolyte in the dispersion medium is above 2%.

Description

Technical Field

[0001] This invention relates to a composition containing an inorganic solid electrolyte, a sheet for an all-solid-state secondary battery, an all-solid-state secondary battery, and a method for manufacturing the sheet for an all-solid-state secondary battery and the all-solid-state secondary battery. Background Technology

[0002] In all-solid-state secondary batteries, all the negative electrode, electrolyte, and positive electrode are made of solids, which can significantly improve the safety and reliability of batteries using organic electrolytes. It also extends battery life. Furthermore, all-solid-state secondary batteries can be configured with electrodes and electrolytes directly arranged and connected in series. Therefore, compared to secondary batteries using organic electrolytes, they can achieve higher energy density and are expected to be used in electric vehicles or large-capacity batteries.

[0003] In such all-solid-state secondary batteries, inorganic solid electrolytes and active materials can be cited as materials forming the constituent layers (solid electrolyte layer, negative electrode active material layer, positive electrode active material layer, etc.). In recent years, inorganic solid electrolytes, especially oxide-based and sulfide-based inorganic solid electrolytes, have attracted attention as electrolyte materials with high ionic conductivity approaching that of organic electrolytes.

[0004] As materials for forming the constituent layers of an all-solid-state secondary battery, all-solid-state secondary batteries containing the aforementioned inorganic solid electrolytes have been proposed. For example, Patent Document 1 describes an all-solid-state secondary battery in which at least one of the constituent layers of the all-solid-state secondary battery—namely, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer—contains an inorganic solid electrolyte. The dispersant contains a compound with a molecular weight of 180 or more and less than 3,000, and has at least one functional group selected from functional group (I): acidic groups, groups having a basic nitrogen atom, thiols, and hydroxyl groups, and an alkyl group with 8 or more carbon atoms or an aryl group with 10 or more carbon atoms. According to the description, the dispersant described in Patent Document 1 can suppress aggregation and form a uniform electrode layer and solid electrolyte layer even when the concentration of either the electrode active material or the inorganic solid electrolyte is high.

[0005] Furthermore, as a material for electrodes used in manufacturing secondary batteries that are not all-solid-state secondary batteries but have a positive electrode, a negative electrode, a separator, and an electrolyte, a slurry (composition) comprising an electrode active material, a conductive material (conductive additive), and a dispersant composed of an ionic surfactant is described. According to this patent document 2, the slurry can improve the dispersibility of the conductive material.

[0006] Previous technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2016-212990

[0009] Patent Document 2: Japanese Patent Application Publication No. 2006-302617 Summary of the Invention

[0010] The technical problem to be solved by the invention

[0011] When the constituent layer is formed by solid particle materials (inorganic solid electrolyte, active material, conductive additive, etc.), from the viewpoint of improving the battery performance (e.g., cycle characteristics) of all-solid-state secondary batteries, it is preferable to have excellent properties such as dispersibility and coating suitability of the constituent layer forming material.

[0012] In recent years, from the perspective of reducing environmental impact and thus manufacturing costs, high-concentration compositions (slurries) with solid component concentrations, for example, exceeding 50% by mass, have been investigated as constituent layer forming materials. However, as the solid component concentration of the composition increases, the properties of the composition typically deteriorate significantly. Therefore, even in high-concentration compositions, it is not easy to achieve constituent layer forming materials with excellent dispersion properties such as suppressing the aggregation of solid particle materials (also known as solid particles), easy formation of a flat coating film (surface properties), or even excellent coating suitability such as the property of close adhesion between solid particles or between solid particles and the substrate (adhesion). Even using the dispersants described in Patent Documents 1 or 2, it is difficult to sufficiently achieve compositions that combine both dispersibility and coating suitability, requiring further research.

[0013] Furthermore, the research and development of high-performance and practical electric vehicles is progressing rapidly, leading to increasingly higher requirements for the battery performance of all-solid-state secondary batteries. To meet these requirements, it is crucial to ensure that the composition and structure of the constituent layer materials exhibit superior properties in order to form the constituent layer.

[0014] The objective of this invention is to provide an inorganic solid electrolyte composition with excellent dispersion characteristics and coating adaptability, which, when used as a constituent layer forming material in an all-solid-state secondary battery, enables excellent cycle characteristics. Furthermore, the objective of this invention is to provide an all-solid-state secondary battery sheet using this inorganic solid electrolyte composition, an all-solid-state secondary battery, and a method for manufacturing the all-solid-state secondary battery sheet and the all-solid-state secondary battery.

[0015] means for solving technical problems

[0016] Based on repeated and in-depth research into the dispersion medium and dispersant used in compositions containing solid particles such as inorganic solid electrolytes, the inventors discovered that by combining inorganic solid electrolytes, using dispersants with SP values, molecular weights, and adsorption rates of inorganic solid electrolytes within specific ranges, and using dispersion media with boiling points within specific ranges, it is possible to suppress the aggregation or precipitation of inorganic solid electrolytes. Therefore, by using this composition containing inorganic solid electrolytes as a constituent layer forming material, they discovered a sheet material for all-solid-state secondary batteries that achieves a flat coating surface with good surface properties and excellent adhesion, as well as an all-solid-state secondary battery with excellent cycle characteristics. Based on these insights, the present invention was completed through further repeated research.

[0017] That is, the above-mentioned problems are solved through the following solutions.

[0018] <1>

[0019] An inorganic solid electrolyte composition for use in an all-solid-state secondary battery, comprising an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, a dispersant and a dispersion medium, wherein the dispersant satisfies the requirements of (1) to (3) below, and the dispersion medium comprises a dispersion medium with a boiling point of 120°C or higher.

[0020] (1) SP value is 17.0~22.0MPa 1 / 2 .

[0021] (2) The molecular weight is below 10,000.

[0022] (3) The adsorption rate of the inorganic solid electrolyte in the above dispersion medium is more than 2%.

[0023] <2>

[0024] According to the inorganic solid electrolyte composition described in <1>, the adsorption rate specified in (3) above is 40% or more.

[0025] <3>

[0026] According to the inorganic solid electrolyte composition described in <1> or <2>, the difference between the SP value of the dispersion medium and the SP value of the dispersant is 3.0 MPa. 1 / 2 the following.

[0027] <4>

[0028] The inorganic solid electrolyte composition according to any one of <1> to <3>, wherein,

[0029] The dispersant described above contains functional groups selected from the functional group (a) below.

[0030] <Functional Groups (a)>

[0031] Hydroxyl, amino, carboxyl, sulfonyl, phosphate, phosphonic acid, thioalkyl, heterocyclic, amide, aryl.

[0032] <5>

[0033] The inorganic solid electrolyte composition according to any one of <1> to <4> contains a polymer binder.

[0034] <6>

[0035] The inorganic solid electrolyte composition according to any one of <1> to <5> contains an active substance.

[0036] <7>

[0037] The inorganic solid electrolyte composition according to any one of <1> to <6> contains a conductive aid.

[0038] <8>

[0039] The inorganic solid electrolyte composition according to any one of <1> to <7>, wherein,

[0040] The aforementioned inorganic solid electrolytes are sulfide-based inorganic solid electrolytes.

[0041] <9>

[0042] A sheet for an all-solid-state secondary battery, having a layer composed of an inorganic solid electrolyte composition as described in any one of <1> to <8>.

[0043] <10>

[0044] A solid-state secondary battery comprises, sequentially, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, wherein...

[0045] At least one of the above-mentioned positive electrode active material layer, the above-mentioned negative electrode active material layer and the above-mentioned solid electrolyte layer has a layer formed by any one of <1> to <8> containing an inorganic solid electrolyte composition.

[0046] <11>

[0047] A method for manufacturing a sheet for an all-solid-state secondary battery, comprising forming a membrane containing an inorganic solid electrolyte composition as described in any one of <1> to <8>.

[0048] <12>

[0049] A method for manufacturing an all-solid-state secondary battery includes a step of assembling an all-solid-state secondary battery sheet obtained by the manufacturing method described in <11> onto an all-solid-state secondary battery.

[0050] Invention Effects

[0051] This invention provides an inorganic solid electrolyte composition with excellent dispersion characteristics (dispersion and stability) and coating suitability (surface properties and adhesion). This inorganic solid electrolyte composition, when used as a constituent layer forming material in an all-solid-state secondary battery, achieves excellent cycle characteristics. Furthermore, this invention provides an all-solid-state secondary battery sheet having a layer composed of this inorganic solid electrolyte composition and an all-solid-state secondary battery. Additionally, this invention provides a method for manufacturing the all-solid-state secondary battery sheet using this inorganic solid electrolyte composition and an all-solid-state secondary battery.

[0052] The above-described features and other features and advantages of the present invention will become more apparent from the accompanying drawings and from the following description. Attached Figure Description

[0053] Figure 1 This is a longitudinal sectional view illustrating a preferred embodiment of the all-solid-state secondary battery of the present invention. Detailed Implementation

[0054] In this invention, the numerical range represented by “~” refers to the range encompassed by the values ​​recorded before and after “~” as the lower limit and upper limit values.

[0055] In this invention, the designation of a compound (e.g., when referred to as a compound by appended terms) means, unless otherwise stated, that the compound includes its salt and its ions in addition to the compound itself. Furthermore, it includes derivatives that modify a portion such as the introduced substituents without impairing the effects of this invention.

[0056] In this invention, (meth)acrylic acid refers to one or both of acrylic acid and methacrylic acid. The same applies to (meth)acrylates.

[0057] In this invention, the term "substituent, linking group, etc." (hereinafter referred to as "substituent, etc.") that is not explicitly stated as substituted or unsubstituted means that the group may also have suitable substituents. Therefore, in this invention, even when simply referred to as a YYY group, the YYY group includes not only those without substituents but also those with substituents. For example, in the case of "alkyl," it refers to both unsubstituted alkyl and substituted alkyl groups. This meaning is the same for compounds where substitution or unsubstituted is not explicitly stated. As a preferred substituent, substituent Z, described later, can be cited as an example.

[0058] In this invention, when specifying the number of carbon atoms of a certain group, unless otherwise stated in this invention or this specification, the number of carbon atoms refers to the total number of carbon atoms in the entire group. That is, when the group also has a substituent, it refers to the total number of carbon atoms including the substituent.

[0059] In this invention, when multiple substituents, etc., are represented by specific symbols, or when multiple substituents, etc., are specified simultaneously or selectively, it means that each substituent, etc., may be the same as or different from each other. Furthermore, even without special explanation, when multiple substituents, etc., are adjacent, it means that they may be linked together or fused together to form a ring.

[0060] In this invention, unless otherwise stated, "polymer" refers to a polymer and is synonymous with "high molecular weight compound." Furthermore, "polymer adhesive" refers to an adhesive composed of polymers, including the polymer itself and adhesives formed containing polymers. However, in this invention, the polymer constituting the polymer adhesive has a mass-average molecular weight exceeding 10,000.

[0061] [Inorganic solid electrolyte composition]

[0062] The inorganic solid electrolyte composition of the present invention is an inorganic solid electrolyte composition for all-solid-state secondary batteries containing an inorganic solid electrolyte having ion conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, a dispersant, and a dispersion medium. The dispersant contained in this inorganic solid electrolyte composition has an SP value, molecular weight, and adsorption rate for the inorganic solid electrolyte that meets the requirements of (1) to (3) described below, and the dispersion medium contains a dispersion medium with a boiling point of 120°C or higher.

[0063] That is, the inorganic solid electrolyte composition of the present invention may contain the above-mentioned inorganic solid electrolyte, the above-mentioned dispersant and the above-mentioned dispersion medium, and there are no particular restrictions on their state or other aspects. However, in the inorganic solid electrolyte composition, the dispersant is preferably adsorbed on the inorganic solid electrolyte within the adsorption rate range specified in (3) above.

[0064] Preferably, the dispersant functions as a binder, that is, in a layer formed at least of an inorganic solid electrolyte composition, it binds solid particles such as inorganic solid electrolytes (and, in addition, coexisting active substances and conductive additives) to each other (e.g., inorganic solid electrolytes to each other, inorganic solid electrolytes and active substances, active substances to each other). Furthermore, it is also preferred to function as a binder for bonding current collectors and solid particles. In the inorganic solid electrolyte composition, the dispersant may or may not have the function of bonding solid particles to each other.

[0065] The aforementioned dispersant has the function of dispersing solid particles in a dispersion medium by adsorbing onto or between solid particles such as inorganic solid electrolytes. Therefore, the inorganic solid electrolyte composition of the present invention is a slurry formed by dispersing inorganic solid electrolytes in a dispersion medium. This improves the dispersion characteristics and coating suitability of the inorganic solid electrolyte composition. Here, the adsorption of solid particles by the dispersant includes not only physical adsorption but also chemical adsorption (adsorption through the formation of chemical bonds, adsorption through electron donation and acceptance, etc.). Furthermore, when the aforementioned dispersant (in a solid state) is dispersed in the dispersion medium, a portion of it can dissolve in the dispersion medium without impairing the effects of the present invention.

[0066] The inorganic solid electrolyte composition of the present invention exhibits excellent dispersion characteristics (dispersion and dispersion stability) and coating suitability (surface properties and adhesion). By using this inorganic solid electrolyte composition as a constituent layer forming material, it is possible to realize an all-solid-state secondary battery sheet with a constituent layer having a flat surface and excellent surface properties, excellent adhesion between solid particles, and excellent cycle characteristics.

[0067] In the manner in which the active material layer formed on the current collector by the inorganic solid electrolyte composition of the present invention is formed, a strong adhesion between the current collector and the active material layer can also be achieved, and the cycling characteristics can be further improved.

[0068] The detailed reasons are still unclear, but the following is believed.

[0069] That is, (1) the SP value is 17.0~22.0MPa 1 / 2 (2) A dispersant with a molecular weight of 10,000 or less and (3) an adsorption rate of 2% or more for inorganic solid electrolytes can exist uniformly around the inorganic solid electrolyte in a dispersion medium containing an inorganic solid electrolyte ...

[0070] If the inorganic solid electrolyte composition of the present invention, which exhibits such excellent dispersion characteristics, is used to form the constituent layer, the formation of inorganic solid electrolyte re-agglomerates or precipitates can be suppressed even during film formation of the constituent layer (e.g., during coating and drying). This suppresses deviations in the contact state between the inorganic solid electrolytes in the constituent layer. In particular, it is considered that when the inorganic solid electrolyte composition contains active materials, specific particles such as active materials are less likely to be unevenly distributed in the constituent layer. Therefore, the generation or enlargement of pores caused by charging and discharging can be suppressed, contributing to the improvement of the cycle characteristics of the all-solid-state secondary battery.

[0071] In addition, the inorganic solid electrolyte composition of the present invention can effectively express the interaction between the particles of the inorganic solid electrolyte, and during film formation, it can improve the dispersion characteristics, resulting in a film with suitable viscosity (flowability). As a result, the coated inorganic solid electrolyte composition flows moderately (leveling), suppressing the generation of severe unevenness caused by insufficient or excessive flow (excellent surface properties of the coated surface), and the interfacial contact state of the solid particles is good (high adhesion) and firmly bonded. Therefore, in the present invention, the concentration of the solid component in the inorganic solid electrolyte composition can be set higher than before, achieving the above-mentioned excellent dispersion characteristics and coating suitability.

[0072] When this inorganic solid electrolyte composition is used to form the constituent layer, the formation of voids is suppressed, while the adhesion between solid particles and even between solid particles and the substrate (current collector) is strengthened, and the current concentration (deterioration of solid particles) on the steep protrusions of the constituent layer surface is suppressed. Therefore, it is believed that an all-solid-state rechargeable battery with excellent cycle characteristics can be achieved without a significant decrease in battery characteristics even with repeated charge and discharge.

[0073] On the other hand, when the inorganic solid electrolyte composition does not contain a dispersion medium with a boiling point of 120°C or higher, even if a dispersant satisfying the requirements of (1) to (3) above is used, the dispersion chain of the compound constituting the dispersant cannot be sufficiently extended in the dispersion medium, resulting in a decrease in dispersion function. Therefore, it is impossible to suppress the aggregation of inorganic solid electrolytes, and sufficient dispersion characteristics cannot be obtained. In particular, the decrease in dispersion function becomes obvious in high-concentration compositions where the concentration of solid components is increased to, for example, 50% by mass or more. Furthermore, in the absence of a dispersion medium with a boiling point of 120°C or higher, rapid drying occurs after coating, thereby promoting the aggregation of inorganic solid electrolytes, and the surface properties and adhesion (coating suitability) are also insufficient.

[0074] There is no particular limitation on the concentration of the solid component in the inorganic solid electrolyte composition, and it can be set appropriately, for example, it can be set to 20-80% by mass, preferably 30-70% by mass, and more preferably 40-60% by mass.

[0075] In this invention, by preparing a composition containing a dispersant satisfying the requirements of (1) to (3) described below, a dispersion medium containing a dispersion medium with a boiling point of 120°C or higher, and an inorganic solid electrolyte, dispersion characteristics and coating suitability can be effectively improved. Therefore, as a composition containing an inorganic solid electrolyte, a high-concentration composition with a higher solid component concentration than before can be prepared. For example, the lower limit of the solid component concentration of the high-concentration composition can be set to 50% by mass or more. The upper limit is less than 100% by mass, for example, it can be set to 90% by mass or less, preferably 85% by mass or less, and more preferably 80% by mass or less.

[0076] In this invention, solid components refer to components other than the dispersion medium described later.

[0077] When the active material layer is formed from the inorganic solid electrolyte composition of the present invention, as described above, the constituent layer is formed while maintaining a highly (uniform) dispersion state immediately after preparation. Therefore, it is believed that by preferentially precipitating solid particles such as dispersants, the contact (adhesion) between the dispersant and the current collector surface is not hindered, and the dispersant can contact (adhere to) the current collector surface while dispersed with solid particles. Thus, the electrode sheet for an all-solid-state secondary battery, in which the active material layer of the inorganic solid electrolyte composition of the present invention is formed on the current collector, achieves a strong adhesion between the current collector and the active material. Furthermore, the all-solid-state secondary battery in which the active material layer of the inorganic solid electrolyte composition of the present invention is formed on the current collector exhibits a strong adhesion between the current collector and the active material and can achieve further improvements in cycle characteristics and conductivity.

[0078] The inorganic solid electrolyte composition of the present invention can be preferably used as a forming material (constituent layer forming material) for all-solid-state secondary battery sheets (including all-solid-state secondary battery electrode sheets) or for forming solid electrolyte layers or active material layers in all-solid-state secondary batteries. In particular, it can be preferably used as a forming material for solid electrolyte sheets or solid electrolyte layers in all-solid-state secondary batteries with an increased content of inorganic solid electrolyte in the solid components, in which high cycle characteristics can also be achieved.

[0079] The viscosity of the inorganic solid electrolyte composition of the present invention at 25°C (room temperature) is not particularly limited. However, from the perspective of improving dispersion characteristics and coating suitability, the viscosity at 25°C is preferably 200–15000 cP, more preferably 200–8000 cP, and even more preferably 400–6000 cP.

[0080] The viscosity of an inorganic solid electrolyte composition can be appropriately set, for example, by changing or adjusting the concentration of the solid components in the inorganic solid electrolyte composition, the type or content of solid particles or dispersants, the type of dispersion medium, and thus the dispersion conditions.

[0081] (Methods for determining slurry viscosity)

[0082] The viscosity of the inorganic solid electrolyte composition is determined by the following method.

[0083] Specifically, using an E-type viscometer (TV-35, manufactured by Toki Sangyo Co., Ltd.) and a standard conical rotor (1”34’×R24), 1.1 mL of the sample (containing an inorganic solid electrolyte composition) was added to a sample cup adjusted to 25°C and placed in the main body. The sample cup was maintained for 5 minutes until the temperature became constant. The measurement range was set to “U”, and the value obtained after 1 minute of rotation at a shear rate of 10 / s (rotation speed of 2.5 rpm) was taken as the viscosity.

[0084] The inorganic solid electrolyte composition of the present invention is preferably a non-aqueous composition. In the present invention, the non-aqueous composition, in addition to being free of water, also contains a water content (also referred to as moisture content) preferably of 500 ppm or less. In the non-aqueous composition, the water content is more preferably 200 ppm or less, further preferably 100 ppm or less, and particularly preferably 50 ppm or less. If the inorganic solid electrolyte composition is a non-aqueous composition, the degradation of the inorganic solid electrolyte can be suppressed. The water content refers to the amount of water contained in the inorganic solid electrolyte composition (mass ratio of the inorganic solid electrolyte composition), specifically, it is defined as the value obtained by filtration using a 0.02 μm membrane filter and determination using Karl Fischer titration.

[0085] The inorganic solid electrolyte composition of the present invention, in addition to containing an inorganic solid electrolyte, a dispersant, and a dispersion medium, also includes, in the form of, an active substance and a conductive additive (the composition in this form is referred to as an electrode composition).

[0086] The components contained in the inorganic solid electrolyte composition of the present invention and the components that may be contained therein will be described below.

[0087] <Inorganic Solid Electrolytes>

[0088] The inorganic solid electrolyte composition of the present invention contains an inorganic solid electrolyte (or, in the case of particulate form, inorganic solid electrolyte particles).

[0089] In this invention, inorganic solid electrolyte refers to an inorganic solid electrolyte, which is a solid electrolyte capable of allowing ions to move within it. It is clearly distinguished from organic solid electrolytes (such as polymeric electrolytes represented by polyethylene oxide (PEO) and organic electrolyte salts represented by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)) from the perspective of not containing organic materials as the primary ion-conducting material. Furthermore, since inorganic solid electrolytes are solid in their stable state, they generally do not dissociate or ionize into cations and anions. In this respect, they are clearly distinguished from inorganic electrolyte salts (such as LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), and LiCl) that dissociate or ionize into cations and anions in electrolytes or polymers. There are no particular limitations as long as the inorganic solid electrolyte possesses the ion conductivity of metals belonging to Group 1 or Group 2 of the periodic table; it generally does not possess electronic conductivity. In the case of the all-solid-state secondary battery of the present invention being a lithium-ion battery, it is preferable that the inorganic solid electrolyte has the ionic conductivity of lithium ions.

[0090] The aforementioned inorganic solid electrolyte can be appropriately selected from solid electrolyte materials commonly used in all-solid-state secondary batteries. For example, as inorganic solid electrolytes, (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 can be mentioned. From the viewpoint of forming a better interface between the active material and the inorganic solid electrolyte, sulfide-based inorganic solid electrolytes are preferred.

[0091] (i) Sulfide-based inorganic solid electrolytes

[0092] The preferred form is a sulfide-based inorganic solid electrolyte containing sulfur atoms, possessing ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and exhibiting electronic insulation properties. The preferred form is a sulfide-based inorganic solid electrolyte containing at least Li, S, and P as elements, and exhibiting lithium-ion conductivity; however, it may contain other elements besides Li, S, and P, depending on the purpose or circumstances.

[0093] As a sulfide-based inorganic solid electrolyte, for example, a lithium-ion conductive inorganic solid electrolyte that satisfies the composition represented by the following formula (S1) can be cited.

[0094] L a1 M b1 P c1 S d1 A e1 (S1)

[0095] In the formula, L represents an element selected from Li, Na, and K, preferably Li. 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 1–12:0–5:1:2–12:0–10. a1 is preferably 1–9, more preferably 1.5–7.5. b1 is preferably 0–3, more preferably 0–1. d1 is preferably 2.5–10, more preferably 3.0–8.5. e1 is preferably 0–5, more preferably 0–3.

[0096] As described below, the composition ratio of each element can be controlled by adjusting the amount of raw material compounds used in the manufacture of sulfide-based inorganic solid electrolytes.

[0097] Sulfide-based inorganic solid electrolytes can be amorphous (glass), crystallized (glass-ceramic), or partially crystallized. For example, Li-PS-based glasses or Li-PS-based glass-ceramics containing Li, P, and S can be used.

[0098] Sulfide-based inorganic solid electrolytes can be manufactured by reacting at least two of the following raw materials: lithium sulfide (Li2S), phosphorus sulfide (e.g., phosphorus pentasulfide (P2S5)), monomeric phosphorus, monomeric sulfur, sodium sulfide, hydrogen sulfide, lithium halides (e.g., LiI, LiBr, LiCl), and sulfides of the element represented by M above (e.g., SiS2, SnS, GeS2).

[0099] The ratio of Li₂S to P₂S₅ in Li-PS-based glasses and Li-PS-based glass ceramics is preferably 60:40 to 90:10, more preferably 68:32 to 78:22, in terms of the molar ratio of Li₂S:P₂S₅. Setting the Li₂S to P₂S₅ ratio within this range improves lithium-ion conductivity. Specifically, the lithium-ion conductivity is preferably set to 1 × 10⁻⁶. -4 S / cm or higher, more preferably 1×10 -3 S / cm or higher. Although no specific upper limit is set, it is actually 1×10⁻⁶. -1 Below S / cm.

[0100] As specific examples of sulfide-based inorganic solid electrolytes, combinations of raw materials are illustrated below. For example, Li₂S-P₂S₅, Li₂S-P₂S₅-LiCl, Li₂S-P₂S₅-H₂S, Li₂S-P₂S₅-H₂S-LiCl, Li₂S-LiI-P₂S₅, Li₂S-LiI-Li₂O-P₂S₅, Li₂S-LiBr-P₂S₅, Li₂S-Li₂O-P₂S₅, Li₂S-Li₃PO₄-P₂S₅, Li₂S-P₂S₅-P₂O₅, Li₂S-P₂S₅-SiS₂, Li₂S-P₂S₅-SiS₂-LiCl, Li₂S-P₂S₅-SnS, and Li₂S-P₂S₅-Al₂ can be cited. S3, Li2S-GeS2, Li2S-GeS2-ZnS, Li2S-Ga2S3, Li2S-GeS2-Ga2S3, Li2S-GeS2-P2S5, Li2S-GeS2-Sb2S5, Li2S-GeS2-Al2S3, Li2S-SiS2, Li2S-Al2S3, Li2S-SiS2-Al2S3, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li 10 GeP2S 12 And so on. The mixing ratio of each raw material is not limited. As a method for synthesizing sulfide-based inorganic solid electrolyte materials using this raw material composition, for example, an amorphization method can be mentioned. As an amorphization method, examples include mechanical polishing, solution processing, and melt quenching. Processing at room temperature is possible, thereby simplifying the manufacturing process.

[0101] (ii) Oxide-based inorganic solid electrolytes

[0102] Oxide-based inorganic solid electrolytes are preferably compounds containing oxygen atoms, possessing ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table, and having electronic insulation properties.

[0103] For oxide-based inorganic solid electrolytes, the preferred ionic conductivity is 1×10⁻⁶. -6 S / cm or higher, preferably 5×10 -6 S / cm or higher, especially preferably 1×10 -5 S / cm or higher. Although there is no specific upper limit, it is actually 1×10 -1 Below S / cm.

[0104] As a specific example of a compound, Li can be cited. xa La yaTiO3 [xa satisfies 0.3≤xa≤0.7, ya satisfies 0.3≤ya≤0.7.] (LLT); Li xb La yb Zr zb M bb mb O nb (M bb It consists of 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 It is an element 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, nd satisfies 3≤nd≤13.) ; Li (3-2xe) M ee xe D ee O(xe) represents a number greater than 0 and less than 0.1, M ee This represents a divalent metal atom. (D) ee This 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, zf satisfies 1 ≤ zf ≤ 10.) ; Li xg S yg O zg (xg satisfies 1≤xg≤3, yg satisfies 0<yg≤2, zg satisfies 1≤zg≤10.) ; Li3BO3; Li3BO3-Li2SO4; Li2O-B2O3-P2O5; Li2O-SiO2; Li6BaLa2Ta2O 12 Li3PO (4-3 / 2w) N w(w satisfies w < 1); Li has a LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4; La with a perovskite-type crystal structure 0.55 Li 0.35 TiO3; LiTi2P3O with a NASICON (Natrium super ionic conductor) crystal structure 12 Li 1+xh+yh (Al, Ga) xh (Ti, Ge) 2-xh Si yh P 3-yh O 12 (xh satisfies 0≤xh≤1, yh satisfies 0≤yh≤1); Li7La3Zr2O has a garnet-type crystal structure. 12 (LLZ) etc.

[0105] Furthermore, phosphorus compounds containing Li, P, and O are preferred. Examples include lithium phosphate (Li3PO4); LiPON, in which nitrogen element replaces a portion of the oxygen element in lithium phosphate; and LiPOD. 1 (D 1 Preferably, it contains one or more elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au.

[0106] Furthermore, LiA can be preferably used. 1 ON(A 1 It consists of one or more elements selected from Si, B, Ge, Al, C, and Ga.

[0107] (iii) Halogen-based inorganic solid electrolytes

[0108] The preferred inorganic solid electrolytes are compounds containing halogen atoms, possessing conductivity of ions belonging to Group 1 or Group 2 of the periodic table, and having electronic insulation properties.

[0109] There are no particular limitations on the type of inorganic solid electrolyte, such as LiCl, LiBr, LiI, and compounds like Li3YBr6 and Li3YCl6 described in ADVANCED MATERIALS, 2018, 30, 1803075. Among these, Li3YBr6 and Li3YCl6 are preferred.

[0110] (iv) Hydride-based inorganic solid electrolytes

[0111] Hydride-based inorganic solid electrolytes are preferably compounds containing hydrogen atoms, possessing ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table, and having electronic insulation properties.

[0112] There are no particular limitations as hydride-based inorganic solid electrolytes; examples include LiBH4, Li4(BH4)3I, and 3LiBH4-LiCl.

[0113] The inorganic solid electrolyte is preferably a particle. In this case, the particle size (volume average particle size) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.1 μm or more. As an upper limit, it is preferably 100 μm or less, more preferably 50 μm or less.

[0114] The particle size of the inorganic solid electrolyte was determined using the following steps. A 1% (w / w) dispersion of the inorganic solid electrolyte particles was prepared by diluting the particles with water (or heptane if water is unstable) in a 20 mL sample vial. The diluted dispersion sample was then irradiated with ultrasound at 1 kHz for 10 minutes and immediately used in the test. Using this dispersion sample, 50 data acquisitions were performed using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA, Ltd.) at 25°C using a measuring quartz cell to obtain the volume average particle size. Other detailed conditions were referenced as needed in Japanese Industrial Standard (JIS) Z8828:2013 "Particle Size Analysis - Dynamic Light Scattering Method". Five samples were prepared for each grade, and their average value was used.

[0115] The inorganic solid electrolyte composition may contain one or more types of inorganic solid electrolytes.

[0116] In the case of forming a solid electrolyte layer, the per unit area (cm²) of the solid electrolyte layer 2 There are no particular limitations on the mass (mg) (weight per unit area) of the inorganic solid electrolyte. It can be appropriately determined based on the designed battery capacity; for example, it can be set to 1–100 mg / cm³. 2 .

[0117] In the case where the inorganic solid electrolyte composition contains the active substance described later, the total amount of the active substance and the inorganic solid electrolyte is preferably within the above range regarding the unit area weight of the inorganic solid electrolyte.

[0118] There is no particular limitation on the content of inorganic solid electrolyte in the inorganic solid electrolyte composition. In terms of dispersion characteristics and coating suitability, it is preferable that the solid content is 50% or more out of 100% by mass, more preferably 70% or more by mass, and especially preferably 90% or more by mass. As an upper limit, from the same point of view, it is preferable that it is 99.9% or less by mass, more preferably 99.5% or less by mass, and especially preferably 99% or less by mass.

[0119] However, when the inorganic solid electrolyte composition contains the active substance described later, the total content of the active substance and the inorganic solid electrolyte in the inorganic solid electrolyte composition is preferably within the range described above.

[0120] <Dispersant>

[0121] The inorganic solid electrolyte composition of the present invention contains a dispersant that satisfies all the requirements of (1) to (3) described below.

[0122] The aforementioned dispersant is any chemical substance capable of dispersing solid particles (dispersion medium) such as inorganic solid electrolytes, active substances, and conductive additives in the dispersion medium described later, and capable of stabilizing the dispersion state (a chemical substance exhibiting a dispersing effect). When used in conjunction with solid particles such as inorganic solid electrolytes in the inorganic solid electrolyte composition of the present invention, the dispersion characteristics and coating suitability of the inorganic solid electrolyte composition (slurry) can be improved.

[0123] Furthermore, the dispersant described above can be a polymer (any polymer is acceptable, including oligomers) or a non-polymer compound (meaning it is not a polymer, hereinafter also referred to as a low molecular weight compound) as long as it meets all the requirements of (1) to (3) described below. In this invention, from the viewpoint that it can be uniformly adsorbed onto inorganic solid electrolytes, can more effectively suppress the aggregation of inorganic solid electrolytes, and further improve the dispersion characteristics and coating suitability of the composition containing inorganic solid electrolytes, a low molecular weight compound is preferred.

[0124] Regulation (1): SP value

[0125] In this invention, the dispersant (a chemical substance exhibiting a dispersing effect) has an SP value of 17.0–22.0 MPa. 1 / 2 Therefore, by allowing the molecular chains to extend around solid particles such as inorganic solid electrolytes and dispersing the solid particles in the presence of a dispersant, the dispersion characteristics and coating suitability of compositions containing inorganic solid electrolytes can be improved. From the viewpoint of dispersing solid particles by allowing the molecular chains to extend around them and in the presence of a dispersant, and further improving dispersion characteristics and coating suitability, the SP value of the dispersant is preferably 17.0 to 21.0 MPa. 1 / 2More preferably, it is 18.0–20.0 MPa. 1 / 2 The difference (absolute value) between the dispersant and the dispersion medium's SP value will be described later.

[0126] When the dispersant is a polymer, the SP value is set to the value obtained by the calculation methods (1) and (2) below. When the dispersant is a low molecular weight compound, the SP value is set to the value calculated by the Hoy method below and converted to MPa. 1 / 2 The value obtained.

[0127] (1) Calculate the SP value of the structural unit.

[0128] First, for polymers, determine the structural units with specified SP values.

[0129] That is, in this invention, when calculating the SP value of a polymer, if the polymer (segment) is a chain polymer, it is designated as a structural unit with the same constituent components as the source compound; if the polymer is a step-polymer (condensation, addition, or addition condensation) polymer such as polyurethane, polyurea, polyamide, polyimide, or polyester, it is designated as a unit with different constituent components from the source compound. For example, taking polyurethane as an example of a step-polymer polymer, the structural unit for specifying the SP value is defined as follows: As a structural unit derived from a polyisocyanate compound, it is a unit formed by bonding an -O- group to one -NH-CO- group and removing the remaining -NH-CO- group relative to the constituent components derived from the polyisocyanate compound (a unit having one urethane bond). On the other hand, as a structural unit derived from a polyol compound, it is a unit formed by bonding a -CO-NH- group to one -O- group and removing the remaining -O- group relative to the constituent components derived from the polyol compound (a unit having one urethane bond). In addition, the structural unit is determined in the same way as for polyurethane in the case of other step-polymer polymers.

[0130] Next, unless otherwise stated, the SP value for each structural element is determined using the Hoy method (refer to HL Hoy Journal of Paint Technology Vol. 42, No. 541, 1970, 76-118 and Polymer Handbook 4). th Chapter 59, VII, page 686 (Tables 5 and 6 and the formulas in Table 6).

[0131] [Formula 1]

[0132]

[0133] In the formula, δ t Indicates the SP value. F tThis represents the Molar attraction function.

[0134] (J×cm 3 ) 1 / 2 / mol, expressed by the following formula. V represents the molar volume (cm3 / mol), expressed by the following formula.

[0135] It is represented by the following formula.

[0136] F t =Σn i F t，i V=Σn i V i

[0137]

[0138] In the above formula, F t，i V represents the molar attraction function of each structural unit. i Δ represents the molar volume of each structural unit. (P) T，i表 This shows the correction values ​​for each structural unit, n. i This represents the number of each structural unit.

[0139] (2) SP value of polymer

[0140] Using the structural elements determined as described above and the calculated SP values, the following formula is used for calculation. Additionally, the SP values ​​of the structural elements obtained from the aforementioned literature are converted to SP values ​​(MPa). 1 / 2 (For example, 1cal) 1 / 2 cm -3 / 2 ≈2.05J 1 / 2 cm -3 / 2 ≈2.05MPa 1 / 2 And use it.

[0141] SP p 2 =(SP1) 2 ×W1)+(SP2 2 ×W2)+……

[0142] In the formula, SP1, SP2, ... represent the SP values ​​of the structural unit, and W1, W2, ... represent the mass fraction of the structural unit.

[0143] In this invention, the mass fraction of the structural unit is the mass fraction of the polymer corresponding to the constituent component (the raw material compound into which the constituent component is introduced) of the structural unit.

[0144] The SP value of a polymer can be adjusted according to the type or composition of the polymer (the types and contents of its constituent components).

[0145] In this invention, the SP value of the polymer is calculated for all structural units using the above formula. When the polymer contains components derived from macromonomers, the SP value calculated using the above formula (excluding MM) can also be set to exclude the structural units corresponding to components derived from macromonomers (MM). Based on the SP value (excluding MM) calculated in this way, the dispersion characteristics can be further improved. The SP value (excluding MM) can also be set to the same range as the SP value described above, preferably 13.0 to 22.5 MPa. 1 / 2 More preferably, it is 16.0–21.0 MPa. 1 / 2 More preferably, it is 17.5–20.5 MPa. 1 / 2 .

[0146] Regulation (2): Molecular weight

[0147] In this invention, the molecular weight of the dispersant is 10,000 or less. This allows the solid particles to be dispersed in the dispersion medium while the dispersant is uniformly present around the inorganic solid electrolyte or other solid particles, thereby improving the dispersion characteristics and coating suitability of the inorganic solid electrolyte-containing composition. Furthermore, from the viewpoint of functioning as a binder to evenly bond the inorganic solid electrolyte or other solid particles in the layer formed by the inorganic solid electrolyte composition of this invention, the molecular weight of the dispersant is preferably 150 or more.

[0148] When the above dispersant is a polymer, the molecular weight of the dispersant refers to the mass-average molecular weight of the polymer, which is determined by the following method.

[0149] From the viewpoint of further improving dispersion characteristics and coating suitability by dispersing the solid particles in a state where the dispersant is more uniformly present around the solid particles in the dispersion medium, the molecular weight of the dispersant is preferably 150 to 8000, more preferably 180 to 6000, even more preferably 200 to 5000, and particularly preferably 230 to 4000. The upper limit of the molecular weight of the dispersant is even more preferably 2000 or less, more preferably 1000 or less, and even more preferably 500 or less.

[0150] -Determination of molecular weight-

[0151] In this invention, the molecular weight of polymers, polymer chains, and macromonomers, unless otherwise specified, refers to the mass-average molecular weight converted from standard polystyrene obtained by gel permeation chromatography (GPC). As a method for determination, methods set to either condition 1 or condition 2 (preferred) can be cited. Appropriate eluents are selected and used according to the type of polymer or macromonomer.

[0152] (Condition 1)

[0153] Column: Connects 2 TOSOH TSKgel Super AWM-H (trade name, manufactured by TOSOH CORPORATION)

[0154] Charge carriers: 10 mM LiBr / N-methylpyrrolidone

[0155] Measurement temperature: 40℃

[0156] Carrier flow rate: 1.0 ml / min

[0157] Sample concentration: 0.1% by mass

[0158] Detector: RI (Refractive Index) Detector

[0159] (Condition 2)

[0160] Tubes: Tubes connected to TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, and TOSOH TSKgel Super HZ2000 (all trade names, manufactured by Tosoh Corporation) are used.

[0161] Support: Tetrahydrofuran

[0162] Measurement temperature: 40℃

[0163] Carrier flow rate: 1.0 ml / min

[0164] Sample concentration: 0.1% by mass

[0165] Detector: RI (Refractive Index) Detector

[0166] Regulation (3): Adsorption rate

[0167] In this invention, the adsorption rate (%) of the dispersant is a value determined using the inorganic solid electrolyte contained in the inorganic solid electrolyte composition and a specific dispersion medium, and is an indicator of the degree to which the dispersant in the dispersion medium is adsorbed onto the inorganic solid electrolyte. Here, the adsorption of the dispersant onto the inorganic solid electrolyte includes not only physical adsorption but also chemical adsorption (adsorption through the formation of chemical bonds, adsorption through electron donation and acceptance, etc.).

[0168] When the inorganic solid electrolyte composition contains multiple inorganic solid electrolytes, the adsorption rate is measured for inorganic solid electrolytes having the same composition (type and content) as the inorganic solid electrolytes in the composition. Similarly, when the inorganic solid electrolyte composition contains multiple specific dispersion media, the adsorption rate is measured using dispersion media having the same composition (type and content) as the specific dispersion media in the composition. Furthermore, when multiple dispersants are used, the adsorption rate is also measured for each dispersant.

[0169] In this invention, the adsorption rate of the dispersant is set as a value calculated by the method described in the examples.

[0170] The adsorption rate of the dispersant is 2% or more. If the dispersant exhibits the aforementioned adsorption rate, the solid particles can be dispersed in the dispersion medium while the dispersant is appropriately adsorbed onto solid particles such as inorganic solid electrolytes, thereby improving the dispersion characteristics and coating suitability of the composition containing inorganic solid electrolytes. From the viewpoint of achieving a higher balance between dispersion characteristics and coating suitability, the adsorption rate is preferably 20% or more, more preferably 40% or more, further preferably 60% or more, and particularly preferably 70% or more. On the other hand, the upper limit of the adsorption rate is not particularly limited, but is practically 90% or less. From the viewpoint of suppressing excessive adsorption of solid particles, the upper limit of the adsorption rate is preferably 95% or less, more preferably 90% or less, and further preferably 85% or less.

[0171] In this invention, the adsorption rate of inorganic solid electrolytes can be appropriately set by the characteristics of the dispersant (e.g., mass-average molecular weight), the type or content of functional groups possessed by the dispersant, and the form of the dispersant (the amount dissolved in the dispersion medium).

[0172] When the inorganic solid electrolyte composition of the present invention contains the active material described later (when an active material layer is formed from the inorganic solid electrolyte composition), the adsorption rate of the dispersant to the active material is not particularly limited. From the viewpoint of enhancing the dispersion characteristics, coating suitability, and adhesion of the solid particles in the inorganic solid electrolyte composition, it is preferably 90% or less, more preferably 0.1 to 60%, and even more preferably 1 to 30%. In the present invention, the adsorption rate of the dispersant to the active material is a value measured using the active material contained in the inorganic solid electrolyte composition and the dispersion medium, and is an indicator of the degree to which the dispersant in the dispersion medium is adsorbed onto the active material. Here, the adsorption of the active material by the dispersant includes not only physical adsorption but also chemical adsorption (adsorption by forming chemical bonds, adsorption by electron donation and acceptance, etc.).

[0173] When the inorganic solid electrolyte composition contains multiple active substances, multiple specific dispersion media, and thus multiple dispersants, the adsorption rate of the dispersant for the inorganic solid electrolyte is the same as that of the aforementioned dispersant. In this invention, the adsorption rate of the dispersant for the active substance is set to a value calculated in the same manner as described in the [Determination of the Adsorption Rate of the Dispersant for the Inorganic Solid Electrolyte] method in the examples, except that the active substance is used instead of the inorganic solid electrolyte. In this invention, the adsorption rate for the active substance can be appropriately set in the same way as the adsorption rate for the inorganic solid electrolyte.

[0174] The dispersant preferably contains functional groups selected from the functional group (a) below. The dispersant contains functional groups selected from the functional group (a) below, thereby allowing these functional groups to function as adsorption groups and improve the adsorption rate of inorganic solid electrolytes.

[0175] When there are two or more dispersants, it is preferred that at least one dispersant contains the functional group, and it is also a preferred method that all dispersants contain the functional group.

[0176] When the dispersant is a polymer, the constituent components of the polymer preferably include functional groups selected from the functional group group (a) below. The constituent components having functional groups have the function of improving the adsorption rate of the dispersant for inorganic solid electrolytes, and can be any constituent component forming the polymer. The functional groups can be incorporated into the main chain of the polymer or into the side chains. When incorporated into the side chains, the functional groups can be directly bonded to the main chain or bonded via a linker. There are no particular limitations on the linker; examples of linkers described in the functional group group (b) described later can be cited. A constituent component may have one or more functional groups, and when it has two or more, they may or may not be bonded to each other.

[0177] <Functional Groups (a)>

[0178] Hydroxyl, amino (-N(R)A 2) Carboxyl, sulfonyl, phosphate, phosphonic acid, thioalkyl, amide (-CO-NR-), heterocyclic, aryl

[0179] The amino, sulfonyl (-SO2(OH)), phosphate (-OPO(OH)2), heterocyclic, and aryl groups contained in functional group (a) are not specifically limited and have the same meaning as the corresponding groups of substituent Z described later. Among them, R in the amino group A R represents a hydrogen atom or an alkyl group. A The alkyl group has a more preferably 1 to 12 carbon atoms, more preferably 1 to 6, and particularly preferably 1 or 2. There are no particular limitations on the phosphonic acid group (-PO(OR)2), for example, phosphonic acid groups with 0 to 20 carbon atoms can be cited. When the ring structure includes an amino group, it is classified as a heterocycle. The aryl group has a more preferably 6 to 13 carbon atoms, more preferably 6 to 10. R in the amide group and phosphonic acid group represents a hydrogen atom or an alkyl group, and the alkyl group in R preferably has a 1 to 20 carbon atoms, more preferably 1 to 12, and even more preferably 1 to 6.

[0180] Among them, hydroxyl, amino, carboxyl, sulfonyl, phosphate, phosphonic acid and thioalkyl groups do not form salts.

[0181] The functional groups of the dispersant are preferably hydroxyl, amino, carboxyl, sulfonyl, phosphate, phosphonic acid, amide, or aryl, and more preferably hydroxyl, amino, carboxyl, amide, or aryl.

[0182] When the dispersant is a polymer, as a polymer component having the above-mentioned functional groups, a component having at least one of a carboxyl group and an aryl group is preferably mentioned, and a component derived from styrene and a component obtained by opening the cyclic anhydride structure in a component derived from a carboxylic anhydride (preferably maleic anhydride) with an alcohol such as methanol or ethanol are more preferably mentioned.

[0183] When the dispersant is a polymer, other constituent components that may be present besides the polymer constituent components having the above-mentioned functional groups include constituent components derived from compounds having carbon-carbon double bonds. For example, constituent components derived from any one of hydrocarbon compounds such as (meth)acrylonitrile, (meth)acrylate compounds, ethylene, propylene, isoprene, and butadiene are preferred.

[0184] The number of the aforementioned functional groups in the dispersant is not particularly limited as long as it achieves the effect of the present invention.

[0185] When the dispersant is a low-molecular-weight compound, it is preferable to have one or more, more preferably one. Furthermore, when a hydroxyl, amino, carboxyl, sulfonyl, phosphate, phosphonic acid, thioalkyl, or amide group from the functional group (a) described above is directly present as a substituent on a heterocyclic or aryl group, the number of functional groups is counted as one. For example, in the illustrative compound C-7 described later, since a hydroxyl group is directly present on the phenyl group, the number of the aforementioned functional groups is one.

[0186] When the dispersant is a polymer, there is no particular limitation on the content of the constituent components having the above functional groups in the polymer, as long as the adsorption rate of the dispersant to the inorganic solid electrolyte is set to 2% or more.

[0187] From the viewpoint of the adhesiveness of solid particles, the content of the constituent components having the above-mentioned functional groups in the polymer is preferably 0.01 to 80 mol%, more preferably 0.01 to 70 mol%, even more preferably 0.1 to 50 mol%, and particularly preferably 0.3 to 50 mol%. The lower limit of the content can also be set to 5 mol% or more or 20 mol% or more.

[0188] When there are two or more dispersants, it is preferable that all dispersants satisfy the above-mentioned number of functional groups in the molecule or the content of polymer components with functional groups.

[0189] When the above-mentioned dispersant is a low molecular weight compound, it is preferably composed of (1)R. X -A 1 (2)R Y -A 2 and (3)HA 3 The compound represented by any one of the above, more preferably, is composed of (1)R X -A 1 and (2)R Y -A 2 Any of the compounds represented in (1)R, more preferably, is a compound derived from (1)R X -A 1 The compound represented.

[0190] In (1) to (3) above, R X R represents an alkyl group. Y A represents an unsubstituted aryl group. 1 ~A 3 This indicates a functional group selected from the functional group (a) mentioned above.

[0191] (The compound mentioned in (1) above)

[0192] As R X The alkyl group can be unsubstituted or substituent. Regarding R... XThe alkyl group can have substituents, such as alkenyl groups and halogen atoms (preferably fluorine atoms). As R X The number of carbon atoms in the alkyl group (including the total number of carbon atoms including the substituents that may be present) is preferably 1 to 20, more preferably 1 to 16, even more preferably 3 to 16, and particularly preferably 8 to 16.

[0193] As A 1 The functional group selected from the functional group (a) above is preferably amino (-N(R) A 2) Carboxyl, sulfonyl, phosphate, phosphonic acid, amide (-CO-NR-) or aryl, more preferably amino, carboxyl, amide or aryl. The R in the amino group... A and R in the amide group and R in the functional group (a) above. A R has the same meaning as R, wherein it is preferably an alkyl group, and more preferably an alkyl group having 1 to 12 carbon atoms.

[0194] And, when A 1 When it is an aryl group, the aryl group can be unsubstituted or substituent, preferably an unsubstituted or substituted phenyl group. Regarding A... 1 The aryl group may have substituents, preferably selected from the functional groups (a) above, more preferably hydroxyl, amino, carboxyl, sulfonyl, phosphate, phosphonic acid or thioalkyl, and even more preferably hydroxyl, amino, carboxyl or thioalkyl.

[0195] From the perspective of further improving dispersion characteristics and coating suitability, A 1 Preferably, it is an aryl group, and more preferably an aryl group having a functional group selected from the functional group (a) above as a substituent.

[0196] (The compound mentioned in (2) above)

[0197] As R Y The unsubstituted aryl group is preferably phenyl.

[0198] A 2 For functional groups selected from the functional group (a) above, the above A can be applied. 2 The records involved.

[0199] (The compound mentioned in (3) above)

[0200] As A 3 The functional group selected from the functional group (a) above is preferably a carboxyl group.

[0201] Specific examples of dispersants include the compounds or polymers shown below, but the present invention is not limited to these. In the specific examples of polymers, the numbers indicated to the lower right of the constituent components indicate the content of the polymer, expressed in moles%.

[0202] [Chemical Formula 1]

[0203]

[0204] The inorganic solid electrolyte composition of the present invention may contain one dispersant or multiple dispersants.

[0205] The dispersant may or may not be soluble in the dispersion medium contained in the inorganic solid electrolyte composition, but it is preferred to be soluble in the dispersion medium. When two or more dispersants are contained, it is preferred that at least one dispersant is soluble, but it is also possible that all dispersants are soluble.

[0206] In this invention, the dispersant being dissolved in the dispersion medium means that the dispersant is dissolved in the dispersion medium containing the inorganic solid electrolyte composition; for example, it means that the solubility is 10% by mass or more in a solubility determination. The method for determining solubility is as follows.

[0207] Specifically, a specified amount of the dispersant to be tested is weighed into a glass bottle, and 100g of a dispersion medium of the same type as that contained in the inorganic solid electrolyte composition is added. The mixture is stirred for 24 hours at 80 rpm on a mixing rotor at 25°C. The transmittance of the mixture obtained after 24 hours of stirring is determined under the following conditions. This test (transmittance determination) is performed by varying the amount of dispersant dissolved (the specified amount mentioned above), and the upper limit concentration X (mass%) of 99.8% transmittance is defined as the solubility of the dispersant in the dispersion medium.

[0208] <Transmittance Measurement Conditions>

[0209] Dynamic light scattering (DLS) measurement

[0210] Apparatus: DLS-8000 DLS measuring device manufactured by Otsuka Electronics Co., Ltd.

[0211] Laser wavelength and output: 488nm / 100mW

[0212] Sample cell: NMR tube

[0213] The total content of dispersant in the inorganic solid electrolyte composition is not particularly limited, but from the viewpoint of improving dispersion characteristics and coating suitability, and further indicating strong adhesion, it is preferably 0.1 to 10.0% by mass, more preferably 0.2 to 5.0% by mass, and even more preferably 0.3 to 4.0% by mass. For the same reason, the total content of dispersant in the inorganic solid electrolyte composition (i.e., the content of dispersant in the inorganic solid electrolyte composition) in 100% by mass of the solid component is preferably 0.1 to 10.0% by mass, more preferably 0.3 to 8.0% by mass, and even more preferably 0.5 to 7.0% by mass.

[0214] When there are two or more dispersants, the content of each dispersant is appropriately set within the range that satisfies the above (total) content.

[0215] In addition, when the dispersant is a polymer, the polymer preferably has the following physical properties or characteristics.

[0216] The water concentration of the polymer is preferably below 100 ppm (by mass). Furthermore, the polymer can be crystallized and dried, or a polymer solution can be used directly.

[0217] The polymer is preferably amorphous. In this invention, "amorphous" typically means that no endothermic peak due to crystal melting is observed when measured at the glass transition temperature.

[0218] <Polymer Adhesives>

[0219] From the viewpoint of further improving dispersion characteristics and coating suitability, it is preferable that the inorganic solid electrolyte composition of the present invention contains a polymer binder in addition to the dispersant described above. It is believed that by using the dispersant and the polymer binder together, a synergistic effect can be achieved, which improves both the dispersion characteristics and coating suitability based on the dispersant and the coating suitability (adhesion) based on the polymer binder.

[0220] It is believed that when the inorganic solid electrolyte composition of the present invention contains a polymer binder, the dispersant with a molecular weight (weight average molecular weight) of 10,000 or less is more preferentially present around the inorganic solid electrolyte or active material and adsorbed compared to the polymer binder with a weight average molecular weight of more than 10,000. That is, it is believed that even when the dispersant and the polymer binder coexist in the composition, the dispersant that satisfies (1) to (3) above helps to improve the dispersion characteristics and coating suitability. On the other hand, it is believed that the polymer binder is preferentially present around the inorganic solid electrolyte or active material and further present around the adsorbed dispersant, further improving the dispersibility, thereby further providing dispersion characteristics and coating suitability.

[0221] As a polymer adhesive, there is no particular limitation as long as it achieves the effect of the present invention, and examples include polymer adhesives composed of fluorinated copolymers or acrylonitrile polymers described later.

[0222] The polymeric binder (also referred to simply as the binder) preferably has an adsorption rate of less than 60% for the inorganic solid electrolyte in the dispersion medium described later in the composition.

[0223] In this invention, the adsorption rate of the adhesive is a value measured using the inorganic solid electrolyte contained in the composition containing the inorganic solid electrolyte and the dispersion medium, and is an indicator of the degree to which the adhesive in the dispersion medium is adsorbed onto the inorganic solid electrolyte. Here, the adsorption of the inorganic solid electrolyte by the adhesive includes not only physical adsorption but also chemical adsorption (adsorption through the formation of chemical bonds, adsorption through electron donation and acceptance, etc.).

[0224] When the inorganic solid electrolyte composition contains multiple inorganic solid electrolytes, the adsorption rate is measured for inorganic solid electrolytes having the same composition (type and content) as the inorganic solid electrolytes in the composition. Similarly, when the inorganic solid electrolyte composition contains multiple dispersion media, the adsorption rate is measured using dispersion media having the same composition (type and content) as the dispersion media in the composition. Furthermore, when multiple binders are used, the adsorption rate is also measured for each binder.

[0225] In this invention, the adsorption rate of the adhesive is set to the value calculated in the same manner as described in the [Determination of the Adsorption Rate of Dispersant to Inorganic Solid Electrolyte] method in the examples, except that an adhesive is used instead of a dispersant.

[0226] If the adsorption rate of the polymer binder is less than 60%, excessive adsorption of the inorganic solid electrolyte can be suppressed, and the dispersion characteristics and coating suitability of the composition containing the inorganic solid electrolyte can be improved. From the viewpoint of achieving a higher balance between dispersion characteristics and coating suitability, the adsorption rate is preferably 50% or less, more preferably 40% or less, further preferably 30% or less, and especially preferably 20% or less. It is also preferably set to 10% or less, more preferably less than 5%. On the other hand, there is no particular limitation on the lower limit of the adsorption rate, and it can also be set to 0%. From the viewpoint of dispersion characteristics and coating suitability, the lower limit of the adsorption rate is preferably small; on the other hand, from the viewpoint of improving the adhesion of the inorganic solid electrolyte, it is preferably more than 0%, more preferably 0.1% or more, and even more preferably 0.5% or more.

[0227] In this invention, the adsorption rate of inorganic solid electrolytes can be appropriately set by the characteristics of the polymer forming the binder (e.g., the content of constituent components, mass-average molecular weight), the type or content of functional groups possessed by the polymer, the form of the binder (the amount dissolved in the dispersion medium), etc.

[0228] Polymer binders may be soluble (solubilizing binders) or insoluble in the dispersion medium contained in the inorganic solid electrolyte composition, but soluble binders that are soluble in the dispersion medium are preferred. In this invention, a binder being soluble in the dispersion medium means having a solubility of 80% by mass or more in a solubility determination. The solubility determination method is set to measure the value in the same manner as in the above-described method for determining the solubility of dispersants, except that a binder is used instead of a dispersant.

[0229] When the inorganic solid electrolyte composition of the present invention contains the active material described later (when an active material layer is formed from the inorganic solid electrolyte composition), the adsorption rate of the polymer binder on the active material is not particularly limited. From the viewpoint of enhancing the dispersion characteristics, coating suitability, and adhesion of the solid particles in the inorganic solid electrolyte composition, it is preferably 90% or less, more preferably 0.1% to 50%, and even more preferably 1% to 10%. In the present invention, the adsorption rate of the binder on the active material is a value measured using the active material contained in the inorganic solid electrolyte composition and the dispersion medium, and is an indicator of the degree to which the binder in the dispersion medium adsorbs the active material. Here, the adsorption of the active material by the binder includes not only physical adsorption but also chemical adsorption (adsorption through the formation of chemical bonds, adsorption through electron donation and acceptance, etc.).

[0230] When the inorganic solid electrolyte composition contains multiple active substances, multiple dispersion media, and consequently multiple binders, the adsorption rate of the inorganic solid electrolyte is the same as that of the aforementioned binders. In this invention, the adsorption rate of the binder for the active substance is set to the value calculated in the same manner as in the [determination of the adsorption rate of the dispersant for the inorganic solid electrolyte] method described in the examples, except that the binder is used instead of the dispersant and the active substance is used instead of the inorganic solid electrolyte. In this invention, the adsorption rate for the active substance can be appropriately set in the same way as the adsorption rate for the inorganic solid electrolyte.

[0231] (Fluoropolymers that constitute polymer adhesives)

[0232] As fluorinated copolymers, copolymers having vinylidene fluoride (VDF) and hexafluoropropylene (HFP) components are preferably examples, including copolymers further having components derived from polymerizable compounds that can copolymerize with VDF and HFP (sometimes referred to as other components). From the viewpoint of having such other components, for convenience, they are referred to as "fluorinated copolymers".

[0233] There are no particular limitations on the polymerizable compounds that can copolymerize with VDF and HFP. For example, polymerizable compounds having at least one carbon-carbon unsaturated bond can be cited. More specifically, polymerizable compounds containing fluorine atoms (fluorinated polymerizable compounds), polymerizable compounds not containing fluorine atoms, and polymerizable compounds having functional groups selected from functional group (b) described below can be cited.

[0234] Fluorinated copolymers include those having components derived from fluorinated polymeric compounds and those not having components derived from fluorinated polymeric compounds, but preferably those having vinylidene fluoride (VDF) and hexafluoropropylene (HFP) components and not having components derived from fluorinated polymeric compounds.

[0235] The VDF constituents that form fluorinated copolymers are derived from vinylidene fluoride and are represented by -CF2-CH2-. The HFP constituents are derived from hexafluoropropylene and are represented, for example, by -CF2-CF(CF3)-.

[0236] There are no particular restrictions on the constituent components of fluorinated polymeric compounds that can form fluorinated copolymers, as long as they are other than VDF and HFP constituent components. The fluorinated polymeric compound into which this constituent component is introduced refers, for example, a compound having fluorine atoms directly or indirectly (e.g., via a linker described later) bonded to carbon-carbon unsaturated bonds. There are no particular restrictions on fluorinated polymeric compounds; examples include fluorinated vinyl compounds such as tetrafluoroethylene, trifluoroethylene, monofluoroethylene, and trifluorochloroethylene, and perfluoroalkyl ether compounds such as trifluoromethyl vinyl ether and pentafluoroethyl vinyl ether.

[0237] Furthermore, the fluorinated polymeric compound comprises a polymeric compound (macromonomer) having a polymeric chain bonded directly or indirectly (e.g., via a linker described later) to a carbon-carbon unsaturated bond. For example, compounds obtained by replacing at least one hydrogen atom of the aforementioned fluorinated polymeric compound with a polymeric chain can be cited. There are no particular limitations on the polymeric chain; common polymer components can be used. Examples include chains of (meth)acrylic resin, chains of polyethylene resin, polysiloxane chains, polyalkylene ether chains, hydrocarbon chains, etc. An example of a fluorinated copolymer having components derived from a polymeric compound having a polymeric chain is shown below. In the copolymers described below, the numbers to the lower right of each component indicate the content (mol%) of the component in the copolymer.

[0238] [Chemical Formula 2]

[0239]

[0240] The constituent component derived from a polymeric compound that does not contain fluorine atoms is a constituent component capable of copolymerizing with vinylidene fluoride or hexafluoropropylene. There are no particular restrictions as long as the constituent component is derived from a compound that does not have fluorine atoms and functional groups selected from functional group (b) described later. Examples of polymeric compounds that do not contain fluorine atoms and are used to introduce this constituent component include polymeric compounds commonly used for chain polymerization, specifically vinyl compounds, diene compounds, etc.

[0241] The constituent components derived from polymerizable compounds that do not have functional groups selected from functional group (b) are not particularly limited as long as they have the aforementioned functional groups. Examples of polymerizable compounds with functional groups that derive such constituent components include polymerizable compounds with the aforementioned functional groups commonly used in chain polymerization. Specifically, examples include vinyl compounds or diene compounds with the aforementioned functional groups, which will be described in detail later.

[0242] The VDF constituent and other constituents forming the fluorinated copolymer may each have substituents. There are no particular restrictions on substituents as long as they do not deviate from the scope of each constituent; for example, groups selected from substituent Z described later, and functional groups selected from functional group (b) described later, can be cited. Furthermore, when the VDF constituent or the like has a functional group selected from functional group (b), it is classified as "a constituent derived from a polymeric compound having a functional group" as described above.

[0243] The aforementioned fluorinated copolymers can be any of the above-mentioned components, block copolymers, alternating copolymers, or random copolymers. From the viewpoint of solubility, random copolymers are preferred.

[0244] This fluorinated copolymer can be synthesized appropriately and can also be used in commercially available products.

[0245] The fluorinated copolymers constituting the polymer adhesive can be one or more types.

[0246] In fluorinated copolymers, the content of HFP (also known as HFP content) is preferably 10 to 70 mol%, more preferably 15 to 65 mol%, among all the components constituting the fluorinated copolymer. This weakens the effect of the polymer binder composed of the fluorinated copolymer on the inorganic solid electrolyte, reducing the aforementioned adsorption rate to less than 60%. From the viewpoint of improving dispersion characteristics and coating suitability, and thus enhancing current collector adhesion, the upper limit of the HFP content is more preferably 60 mol% or less, further preferably 50 mol% or less, particularly preferably 45 mol% or less, and most preferably 40 mol% or less. On the other hand, from the viewpoint of improving dispersion characteristics and coating suitability, and thus enhancing current collector adhesion, the lower limit of the HFP content is more preferably 15 mol% or more, further preferably 20 mol% or more, particularly preferably 30 mol% or more, and most preferably 35 mol% or more. The HFP content of the fluorinated copolymer can be determined by measuring the nuclear magnetic resonance (NMR) spectrum of the copolymer (NMR determination method). Furthermore, for fluorinated copolymers in the composition, for example, fluorinated copolymers extracted from tetrahydrofuran (THF) are used for determination. Also, for fluorinated copolymers in the constituent layers of all-solid-state secondary battery sheets or all-solid-state secondary batteries, for example, the constituent layers obtained by decomposing the sheet or battery and peeling off the constituent layers containing polymer binders using THF are determined using extracted fluorinated copolymers.

[0247] In fluorinated copolymers, the content of VDF components (also known as VDF amount) is not particularly limited. However, from the viewpoint of improving dispersion characteristics and coating suitability, and thus enhancing current collector adhesion, the VDF amount is preferably 30 to 90 mol%, more preferably 35 to 85 mol%, further preferably 40 to 80 mol%, and especially preferably 50 to 75 mol%. The VDF amount can be determined using fluorinated copolymers extracted in the same manner as the determination of HFP amount and according to NMR determination.

[0248] Furthermore, in fluorinated copolymers, the ratio of VDF to HFP (VDF amount / HFP amount) is not particularly limited. From the viewpoint of improving dispersion characteristics and coating suitability, and thus enhancing the adhesion of current collectors, it is preferably 0.5 to 5, and more preferably 1 to 3.

[0249] In fluorinated copolymers, there is no particular limitation on the total content of components derived from copolymerizable polymerizable compounds; for example, it can be set to less than 50 mol%.

[0250] In copolymerizable polymeric compounds, the content of components derived from fluorinated polymeric compounds or polymeric compounds without fluorine atoms is appropriately set within a range that does not impair excellent dispersion characteristics and coating suitability, taking into account factors such as the adsorption rate of the polymer binder, tensile fracture strain, and the adhesive force of solid particles. The content of components derived from fluorinated polymeric compounds is preferably 0 to 45 mol%, more preferably 2 to 40 mol%, among all components constituting the fluorinated copolymer. The content of components derived from polymeric compounds without fluorine atoms is preferably 0 to 30 mol%, more preferably 1 to 25 mol%, among all components constituting the fluorinated copolymer.

[0251] When the fluorinated copolymer has components derived from polymeric compounds having functional groups selected from functional group (b) (components having functional groups), their content can be appropriately determined taking into account the adsorption rate of the polymer binder, tensile fracture strain, and the bonding force of the solid particles. For example, from the viewpoint of maintaining excellent dispersion characteristics and coating suitability while making the bonding force of the solid particles and the adhesion to the current collector stronger, the content of all components constituting the fluorinated copolymer is preferably 0.01 to 10 mol%, more preferably 0.01 to 5 mol%, and even more preferably 0.02 to 2 mol%.

[0252] Fluorinated copolymers containing components having functional groups selected from group (b) below (components having functional groups) are also a preferred embodiment. Components having functional groups have the function of improving the adsorption rate of the adhesive for inorganic solid electrolytes. These components, in addition to components derived from polymerizable compounds having functional groups, also include components derived from polymerizable compounds constituting functional groups that are copolymerizable compounds. Examples of components derived from polymerizable compounds constituting functional groups include components derived from polymerizable carboxylic anhydrides such as maleic anhydride.

[0253] The aforementioned functional groups can be any constituent that forms a fluorinated copolymer, preferably other than VDF constituents, HFP constituents, and constituents derived from polymeric compounds that do not contain fluorine atoms. The functional groups can be incorporated into the polymer backbone or into the side chains.

[0254] In this invention, the polymer backbone refers to all other molecular chains constituting the polymer that can be considered branched or comb-like linear molecular chains relative to the backbone. While the weight-average molecular weight depends on the molecular chains considered branched or comb-like, typically the longest chain constituting the polymer becomes the backbone. However, terminal groups present at the ends of the polymer are not included in the backbone. Furthermore, the polymer side chains refer to molecular chains other than the backbone, including both short and long molecular chains.

[0255] <Functional Groups (b)>

[0256] Hydroxyl, amino, carboxyl, sulfonyl, phosphate, phosphonic acid (-PO(OR)2), thioalkyl, ether (-O-), imino (=NR, -NR-), ester (-CO-O-), amide (-CO-NR-), carbamate (-NR-CO-O-), urea (-NR-CO-NR-), heterocyclic, aryl, carboxylic anhydride, isocyanate (-NCO), alkoxysilyl

[0257] The amino, sulfonyl, phosphate, heterocyclic, aryl, and alkoxysilyl groups included in functional group (b) are not particularly limited, and have the same meaning as the corresponding groups of substituent Z described later. The amino group is more preferably 0 to 12 carbon atoms, further preferably 0 to 6, and especially preferably 0 to 2. There are no particular limitations on the phosphonic acid group; for example, phosphonic acid groups with 0 to 20 carbon atoms can be cited. Hydroxyl, amino, carboxyl, sulfonyl, phosphate, phosphonic acid, and thioalkyl groups can form salts. R in each bond represents a hydrogen atom or a substituent, preferably a hydrogen atom. There are no particular limitations on the substituents, which are selected from substituent Z described later, and preferably alkyl.

[0258] There are no particular limitations on the carboxylic anhydride group, including groups formed by removing one or more hydrogen atoms from a carboxylic anhydride (e.g., groups represented by formula (2a) below), and constituent components formed by copolymerizing polymerizable carboxylic anhydrides as copolymerizable compounds (e.g., constituent components represented by formula (2b) below). Groups formed by removing one or more hydrogen atoms from a carboxylic anhydride are preferably groups formed by removing one or more hydrogen atoms from a cyclic carboxylic anhydride. Carboxylic anhydride groups derived from cyclic carboxylic anhydrides are also equivalent to heterocyclic groups, but are classified as carboxylic anhydride groups in this invention. Examples include acyclic carboxylic anhydrides such as acetic anhydride, propionic anhydride, and benzoic acid rod, and cyclic carboxylic anhydrides such as maleic anhydride, phthalic anhydride, fumaric acid rod, and succinic anhydride. There are no particular limitations on the polymerizable carboxylic anhydride, and carboxylic anhydrides having intramolecular unsaturated bonds can be cited, with polymerizable cyclic carboxylic anhydrides being preferred. Specifically, maleic anhydride can be cited.

[0259] Examples of carboxylic anhydride groups include groups represented by formula (2a) or constituents represented by formula (2b), but the invention is not limited to these. In each formula, * indicates a bonding position.

[0260] [Chemical Formula 3]

[0261]

[0262] The functional group selected from functional group (b) is preferably a hydroxyl group, a carboxyl group, a phosphonic acid group, a heterocyclic group or a carboxylic anhydride group, and more preferably a carboxylic anhydride group.

[0263] There are no particular limitations on the methods for incorporating functional groups into polymer chains. Examples include methods for using polymerizable compounds that can copolymerize polymeric compounds having functional groups selected from group (b), methods using polymerization initiators or chain transfer agents having (generating) the aforementioned functional groups, and methods utilizing polymer reactions.

[0264] There are no particular limitations on the polymerizable compounds having the aforementioned functional groups. Examples include polymerizable compounds having at least one carbon-carbon unsaturated bond and the aforementioned functional group. Examples include compounds formed by direct bonding of carbon-carbon unsaturated bonds to the aforementioned functional groups, compounds formed by bonding carbon-carbon unsaturated bonds to the aforementioned functional groups via linking groups, and compounds in which the functional groups themselves contain carbon-carbon unsaturated bonds (e.g., the aforementioned polymerizable cyclic carboxylic anhydrides). Compounds in which the functional groups themselves contain carbon-carbon unsaturated bonds are preferred, and maleic anhydride is more preferred.

[0265] There are no particular limitations on carbon-carbon unsaturated bonds; examples include vinyl and (meth)acryloyl groups.

[0266] There are no particular limitations on the linking group connecting the carbon-carbon unsaturated bond and the above-mentioned functional group. Examples include alkylene groups (preferably 1 to 12 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3), alkenyl groups (preferably 2 to 6 carbon atoms, more preferably 2 to 3), aryl groups (preferably 6 to 24 carbon atoms, more preferably 6 to 10), oxygen atoms, sulfur atoms, and imino groups (-NR). N -), carbonyl, phosphate linker (-OP(OH)(O)-O-), phosphonic acid linker (-P(OH)(O)-O-), or groups related to combinations thereof. It is also possible to combine alkylene and oxygen atoms to form a polyalkoxide chain. Preferably, the linker is a group composed of at least two of alkylene, arylene, carbonyl, oxygen, sulfur, and imino groups; more preferably, it is a group composed of at least two of alkylene, arylene, carbonyl, oxygen, and imino groups; and even more preferably, it contains a -CO-O- group or a -CO-N(R) group. N )-base(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. Particularly preferred are -CO-O- or -CO-N(R) groups. N The linking group is a group formed by combining an alkylene group with a polyalkoxide chain. The linking group may have groups other than those selected from functional group (b). The number of atoms constituting the linking group and the number of linking atoms are described later. However, the polyalkoxide chain constituting the linking group is not limited to those described above. Examples of substituents other than the functional groups described above include the substituent Z described later, such as alkyl or halogen atoms.

[0267] In this invention, the number of atoms constituting the linking 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 linking atoms in the linking group is preferably 10 or less, more preferably 8 or less. A lower limit is 1 or more. The above-mentioned number of linking atoms refers to the minimum number of atoms connecting the defined structural parts. For example, in the case of -CH2-C(=O)-O-, the number of atoms constituting the linking group is 6, but the number of linking atoms is 3.

[0268] A constituent component may have one or more functional groups. When it has two or more functional groups, they may or may not bond with each other.

[0269] The following are specific examples of polymeric compounds with functional groups, but are not limited to these.

[0270] [Chemical Formula 4]

[0271]

[0272] -Substituent Z-

[0273] Examples of alkyl groups include alkyl groups (preferably alkyl groups with 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, tert-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl groups (preferably alkenyl groups with 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl groups (preferably alkynyl groups with 2 to 20 carbon atoms, such as ethynyl, butyrynyl, phenylethynyl, etc.), and cycloalkyl groups (preferably cycloalkyl groups with 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.). When the alkyl group is used, it usually indicates the presence of a cycloalkyl group, but it is described separately here. ), aryl (preferably an aryl group with 6 to 26 carbon atoms, such as phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl (preferably an aralkyl group with 7 to 23 carbon atoms, such as benzyl, phenethyl, etc.), heterocyclic group (preferably a heterocyclic group with 2 to 20 carbon atoms, more preferably a heterocyclic group having a 5 or 6-membered ring having at least one oxygen atom, sulfur atom, and nitrogen atom). Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups. For example, tetrahydropyran can be cited. Cycloyl group, tetrahydrofuran cycloyl group, 2-pyridyl group, 4-pyridyl group, 2-imidazolyl group, 2-benzimidazolyl group, 2-thiazolyl group, 2-oxazolyl group, pyrrolidone group, etc.), alkoxy group (preferably alkoxy group with 1 to 20 carbon atoms, such as methoxy group, ethoxy group, isopropoxy group, benzyloxy group, etc.), aryloxy group (preferably aryloxy group with 6 to 26 carbon atoms, such as phenoxy group, 1-naphthoxy group, 3-methylphenoxy group, 4-methoxyphenoxy group, etc.), heterocyclic oxy group (a group with a -O- group bonded to the above heterocyclic group), alkoxycarbonyl group (preferably alkoxycarbonyl group with 2 to 20 carbon atoms). Examples include ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, etc.; aryloxycarbonyl (preferably aryloxycarbonyl with 6 to 26 carbon atoms, such as phenoxycarbonyl, 1-naphthoxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.); amino (preferably containing amino, alkylamino, or arylamino with 0 to 20 carbon atoms, such as amino(-NH2), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, aniline, etc.); and aminosulfonyl (preferably aminosulfonyl with 0 to 20 carbon atoms, such as N,N-dimethylaminosulfonyl, N-phenylaminosulfonyl, etc.), acyl groups (including alkyl carbonyl, alkenyl carbonyl, alkynyl carbonyl, aryl carbonyl, heterocyclic carbonyl, preferably acyl groups with 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryl, methacryl, crotonyl, benzoyl, naphthoyl, nicotinyl, etc.), acyloxy groups (including alkyl carbonyloxy, alkenyl carbonyloxy, alkynyl carbonyloxy, heterocyclic carbonyloxy, preferably acyloxy groups with 1 to 20 carbon atoms, such as acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyl, etc.), Acryloyloxy, methacryloyloxy, crotonyloxy, nicotinoxy, etc.), aromatic acryloyloxy (preferably aromatic acryloyloxy with 7 to 23 carbon atoms, such as benzoyloxy, naphthyloxy, etc.), carbamoyl (preferably carbamoyl with 1 to 20 carbon atoms, such as N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), amide (preferably amide with 1 to 20 carbon atoms, such as acetamido, benzoylamino, etc.), alkylthio (preferably alkylthio with 1 to 20 carbon atoms, such as methylthio, ethylthio, isopropylthio, benzylthio, etc.) Arylthioyl (preferably arylthioyl with 6 to 26 carbon atoms, such as phenylthioyl, 1-naphthioyl, 3-methylphenylthioyl, 4-methoxyphenylthioyl, etc.), heterocyclic thioyl (a group with -S- group bonded to the above heterocyclic group), alkylsulfonyl (preferably alkylsulfonyl with 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl (preferably arylsulfonyl with 6 to 22 carbon atoms, such as benzenesulfonyl, etc.), alkylsilyl (preferably alkylsilyl with 1 to 20 carbon atoms, such as monomethylsilyl, dimethylsilyl, trimethylsilyl, etc.). alkylsilyl, triethylsilyl, etc.), arylsilyl (preferably arylsilyl with 6 to 42 carbon atoms, such as triphenylsilyl), alkoxysilyl (preferably alkoxysilyl with 1 to 20 carbon atoms, such as monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl, etc.), aryloxysilyl (preferably aryloxysilyl with 6 to 42 carbon atoms, such as triphenoxysilyl), phosphoryl (preferably phosphoric acid with 0 to 20 carbon atoms, such as -OP(=O)(R, P )2) Phosphonyl group (preferably a phosphonyl group with 0 to 20 carbon atoms, for example, -P(=O)(R P )2) Oxyphosphin group (preferably oxyphosphin group with 0 to 20 carbon atoms, for example, -P(R P 2) Sulfonate (sulfonic acid group), carboxyl group, hydroxyl group, thioalkyl group, cyano group, halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). R P It is a hydrogen atom or a substituent (preferably a group selected from substituent Z).

[0274] Furthermore, each of the groups listed in these substituents Z can be further replaced by the aforementioned substituents Z.

[0275] The aforementioned alkyl, alkylene, alkenyl, alkenylene, ynyl, and ynylene groups can be cyclic or chain-like, and can be straight-chain or branched.

[0276] When synthesizing fluorinated copolymers, there are no particular restrictions on the polymerization method of the raw material compounds (VDF, HFP and copolymerizable polymerizable compounds). Well-known methods can be selected and the conditions can be set appropriately.

[0277] (Acrylonitrile polymers (polymers) that constitute polymeric adhesives)

[0278] As an acrylonitrile polymer, it can be either a homopolymer or a copolymer, as long as it contains an acrylonitrile component. In the case of an acrylonitrile copolymer, the content of the acrylonitrile component in the copolymer is preferably 20 to 80 mol%, more preferably 30 to 75 mol%, and even more preferably 40 to 70 mol%. The acrylonitrile component can be a methacrylonitrile component or a mixture thereof.

[0279] Examples of copolymers that copolymerize with acrylonitrile include (meth)acrylic acid compounds, (meth)acrylate compounds and (meth)acrylamide compounds, vinyl alcohol, vinyl alcohol acetal, vinyl acetate, vinyl ester and vinyl ether, and hydrocarbon compounds such as styrene, ethylene, propylene, isoprene and butadiene.

[0280] Among them, acrylonitrile homopolymers are preferred.

[0281] (Physical properties or characteristics of polymer adhesives or fluorinated copolymers constituting polymer adhesives)

[0282] The polymer binder is not particularly limited, but its peel strength relative to the aluminum foil is preferably 0.1 N / mm or higher. This imparts strong current collector adhesion to the active material layer and helps to further improve the cycle characteristics of the all-solid-state secondary battery. From the viewpoint of further improving current collector adhesion and cycle characteristics, the peel strength of the fluorinated copolymer is more preferably 0.2 N / mm or higher, and even more preferably 0.3 N / mm or higher. There is no particular upper limit; for example, it is practically 10 N / mm or lower, and preferably 2.0 N / mm or lower. In this invention, the peel strength can be appropriately set by changing the composition of the polymer constituting the polymer binder, changing the physical properties of the polymer binder, etc.

[0283] A solution (solid content concentration: 10% by mass) of a polymer adhesive dissolved in an organic solvent (butyl butyrate) was dropped onto aluminum foil (trade name: A1N30, manufactured by Hohsen Corp.) and dried (temperature: 100°C, time: 180 minutes) to prepare a 50 μm thick dried film (width: 10 mm, length: 50 mm). This film was used as a test piece to determine the peel strength. Regarding the test methods and conditions, a tensile testing machine (ZTS-50N, manufactured by IMADA CO.,LTD.) was used to measure the peel force when the obtained dried film was peeled from the coated surface of the aluminum foil at a 90° angle at a speed of 30 mm / s. The average value of this value was taken as the peel strength (unit: N / mm).

[0284] The moisture concentration of the polymer binder is preferably below 100 ppm (by mass). Furthermore, this polymer binder can either crystallize and dry the polymer, or be used directly as a polymer binder dispersion.

[0285] The polymer constituting the polymer binder is preferably amorphous. In this invention, "amorphous" typically means that no endothermic peak due to crystal melting is observed when measured at the glass transition temperature.

[0286] When the polymer adhesive is in particulate form, its shape is not particularly limited and can be flat, amorphous, etc., but is preferably spherical or particulate. Its average primary particle size is not particularly limited, but is preferably 0.1 nm or more, more preferably 1 nm or more, further preferably 5 nm or more, especially preferably 10 nm or more, and most preferably 50 nm or more. As an upper limit, it is preferably 5.0 μm or less, more preferably 1.0 μm or less, further preferably 700 nm or less, and especially preferably 500 nm or less.

[0287] The average particle size of the polymer binder can be measured in the same manner as the average particle size of the aforementioned inorganic solid electrolyte.

[0288] In addition, the average particle size of the polymer binder in the constituent layer of the all-solid-state secondary battery can be determined, for example, by disassembling the battery and peeling off the constituent layer containing the polymer binder, measuring the constituent layer, and removing the measured values ​​of the particle size of particles other than the polymer binder that have been measured in advance.

[0289] For example, the average particle size of polymer adhesives can be adjusted by the type of dispersion medium and the content of constituent components in the polymer.

[0290] The tensile breaking strain of the fluorinated copolymer constituting the polymer binder is preferably 500% or more. If the aforementioned specific fluorinated copolymer exhibits a tensile breaking strain of 500% or more, then in the inorganic solid electrolyte composition, as described above, the interaction between solid particles can be maintained and the repulsive force between fluorine atoms on the solid particles can be effectively utilized, improving dispersion characteristics or coating suitability, resulting in strong adhesion of the solid particles and further improving cycle characteristics. In this invention, the tensile breaking strain is more preferably 600% or more, further preferably 700% or more, particularly preferably 750% or more, and most preferably 2500% or more. There is no particular upper limit to the tensile breaking strain; it is practically 10000%, preferably 6000% or less, and more preferably 3500% or less.

[0291] In this invention, the tensile fracture strain can be appropriately set by changing the molecular weight of the fluorinated copolymer, etc.

[0292] Tensile fracture strain was determined by preparing test pieces according to the methods and conditions described in Japanese Industrial Standard (JIS) K 7161 (2014), "Method for Determining Tensile Properties of Plastics." Specifically, a cast film with a thickness of approximately 200 μm was prepared using a solution obtained by dissolving a fluorinated copolymer in, for example, DIBK (diisobutyl ketone). This cast film was cut into 10 mm × 20 mm pieces and placed on a tensile testing machine with a clamp spacing (distance between clamps) of 10 mm. A tensile test (stress and strain line evaluation) was performed at a test speed of 30 mm / min, thereby determining the tensile fracture strain. The tensile fracture strain is the elongation at break obtained by subtracting 100% from the length of the test piece at fracture (% conversion value), with the length of the test piece before stretching set as 100%.

[0293] There is no particular limitation on the weight-average molecular weight of the polymer constituting the polymeric adhesive, provided it exceeds 10,000, but it is preferably between 10,000 and 1,500,000. If the polymer constituting the polymeric adhesive has a weight-average molecular weight within the above-mentioned range, the dispersion characteristics and coating suitability can be further improved, and the tensile breaking strain of the fluorinated copolymer can also be increased. From the viewpoint of dispersion characteristics and coating suitability, a weight-average molecular weight of 20,000 to 1,000,000 is more preferred, 20,000 to 500,000 is more preferably preferred, and 30,000 to 300,000 is particularly preferred. The molecular weight is set as a value obtained by the method described in the dispersant section above.

[0294] From the viewpoint of the dispersion stability of solid particles, the polymer constituting the polymer binder preferably has an SP value of 9 to 23, more preferably 10 to 18, and even more preferably 11 to 15. The difference (absolute value) between the SP value of the fluorinated copolymer and the dispersion medium will be described later. The SP value of the polymer constituting the polymer binder is set as a value obtained by the calculation and conversion method described above when the dispersant is a polymer. In addition, the SP value of the VDF component is 13.1, and the SP value of the HFP component is 9.5. In the above, the unit of SP value is MPa. 1 / 2 .

[0295] Fluorinated copolymers preferably satisfy the above-mentioned physical properties, but from the viewpoints of dispersion characteristics and coating suitability, as well as adhesion, current collector adhesion and resistance suppression, the polymers shown below are more preferred.

[0296] A fluorinated copolymer, wherein the HFP content is 30-40 mol%, a small amount of carboxylic anhydride groups (preferably maleic anhydride groups) are introduced as functional groups (as described above), the tensile fracture strain is 2500-3500%, and the adsorption rate of the polymer binder for inorganic solid electrolytes is greater than 0% and less than 5%.

[0297] The polymer constituting the polymer binder can be either a non-crosslinked polymer or a crosslinked polymer. Furthermore, when the polymer is crosslinked by heating or applying voltage, the molecular weight can be greater than the aforementioned molecular weight. Preferably, when starting to use an all-solid-state secondary battery, the mass-average molecular weight of the polymer is within the aforementioned range.

[0298] The inorganic solid electrolyte composition of the present invention may contain one polymer binder or multiple binders.

[0299] There is no particular limitation on the content of polymer binder in the composition containing inorganic solid electrolyte, but from the viewpoint of dispersion characteristics, coating suitability, and thus adhesion, it is preferred to be 0.1 to 10.0% by mass, more preferably 0.2 to 5.0% by mass, and even more preferably 0.3 to 4.0% by mass in 100% by mass of solid content.

[0300] When the inorganic solid electrolyte composition contains particulate binders (described later), the content of the polymer binder can be lower than the content of the particulate binder, but is preferably the same or higher. This further enhances adhesion without compromising excellent dispersion characteristics and coating suitability. The difference (absolute value) between the contents of the polymer binder and the particulate binder is not particularly limited; for example, it can be set to 0-8% by mass, more preferably 0-4% by mass, and even more preferably 0-2% by mass. Furthermore, the ratio of the contents of the polymer binder to the particulate binder (content of polymer binder / content of particulate binder) is not particularly limited; for example, it is preferably 0.01-10, more preferably 0.02-5.

[0301] In this invention, the mass ratio of the total mass of the inorganic solid electrolyte and the active material to the total mass of the binder [(mass of inorganic solid electrolyte + mass of active material) / (total mass of binder)] is preferably in the range of 1,000 to 1. Furthermore, this ratio is more preferably 500 to 2, and even more preferably 100 to 10.

[0302] (Particle-like adhesive)

[0303] In addition to the polymer binder described above, the inorganic solid electrolyte composition of the present invention preferably contains a particulate polymer binder (particulate binder) that is insoluble in the composition as a dispersion medium. The shape of the particulate binder is not particularly limited and can be flat, amorphous, etc., but is preferably spherical or granular. The average particle size of the particulate binder is preferably 1–1000 nm, more preferably 10–800 nm, further preferably 20–500 nm, and particularly preferably 40–300 nm. The average particle size can be measured in the same manner as the average particle size of the inorganic solid electrolyte described above.

[0304] The particulate adhesive is preferably an adhesive with an adsorption rate of 60% or higher for inorganic solid electrolytes. The adsorption rate can be measured in the same manner as that for polymer adhesives.

[0305] If the inorganic solid electrolyte composition contains particulate binders, the improvement in dispersion characteristics and coating suitability based on polymer binders is not impaired, and the adhesion of solid particles is enhanced while suppressing the increase in interfacial resistance. As a result, cycle characteristics can be further improved for all-solid-state secondary batteries, and preferably, further reduction in resistance can be achieved.

[0306] As particulate binders, various particulate binders for manufacturing all-solid-state secondary batteries can be used without particular limitations. For example, particulate binders composed of step-polymer or chain-polymer polymers can be cited. Furthermore, binders described in Japanese Patent Application Publication No. 2015-088486, International Publication No. 2018 / 020827, etc., can also be cited.

[0307] There are no particular limitations on step-polymers; examples include polyurethanes, polyureas, polyamides, polyimides, polyesters, and polycarbonates. There are also no particular limitations on chain polymers; examples include fluoropolymers (also known as fluoropolymers), hydrocarbon polymers, ethylene polymers, and (meth)acrylic acid polymers.

[0308] The content of the particulate binder in the inorganic solid electrolyte composition is not particularly limited. However, from the viewpoint of improving dispersion characteristics and coating suitability, and thus exhibiting adhesion, it is preferably 0.02 to 5.0% by mass, more preferably 0.05 to 3.0% by mass, and even more preferably 0.1 to 2.0% by mass in 100% by mass of the solid component. In addition, the content of the particulate binder can be appropriately set within the above range, but considering the solubility of the particulate binder, it is preferable to have a content that is insoluble in the inorganic solid electrolyte composition.

[0309] The inorganic solid electrolyte composition of the present invention may contain adhesives other than the polymer adhesives and particulate adhesives mentioned above.

[0310] <Dispersion Medium>

[0311] The dispersion medium contained in the inorganic solid electrolyte composition of the present invention is an organic compound that appears liquid in the environment of use. Any dispersion medium that disperses the solid particles, such as the inorganic solid electrolyte, contained in the composition is acceptable. Examples include various organic solvents, specifically alcohols, ethers, amides, amines, ketones, aromatics, aliphatic compounds, nitriles, and esters. The dispersion medium contained in the inorganic solid electrolyte composition of the present invention includes a dispersion medium with a boiling point of 120°C or higher. In the present invention, boiling point refers to the boiling point of the dispersion medium at atmospheric pressure (1 atmosphere).

[0312] The dispersant with a boiling point of 120°C or higher is preferably 130°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher. The upper limit of the boiling point is preferably 230°C or lower, more preferably 200°C or lower, and even more preferably 180°C or lower.

[0313] The inorganic solid electrolyte composition of the present invention may contain a dispersion medium that does not meet the above-mentioned boiling point, within the range that allows the effects of the present invention to be achieved. For example, in the inorganic solid electrolyte composition of the present invention, the proportion of the dispersion medium having a boiling point of 120°C or higher can be set to 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. There is no particular limitation on the upper limit, and all dispersion media can be set to dispersion media with a boiling point of 120°C or higher.

[0314] The boiling point of the dispersion medium that does not meet the above boiling point is not particularly limited, but is preferably 90°C or higher. The upper limit of the boiling point is appropriately determined according to the relationship with the dispersion medium with a boiling point of 120°C or higher, and can be set to a temperature lower than the boiling point of the dispersion medium with a boiling point of 120°C or higher.

[0315] The dispersion medium can be a nonpolar dispersion medium (hydrophobic dispersion medium) or a polar dispersion medium (hydrophilic dispersion medium). From the viewpoint of exhibiting excellent dispersibility, a nonpolar dispersion medium is preferred. A nonpolar dispersion medium generally refers to a medium with low affinity for water; however, in this invention, examples include ester compounds, ketone compounds, ether compounds, aromatic compounds, and aliphatic compounds.

[0316] In this invention, the dispersant and the substance in the dispersion medium that does not function as a dispersant for solid particles such as inorganic solid electrolytes are defined as the dispersion medium. Therefore, when a composition containing inorganic solid electrolytes contains two or more dispersion media, the substance in the dispersion medium that functions as a dispersant in the preparation of the inorganic solid electrolyte composition is classified as a dispersant, not a dispersion medium. Whether it functions as a dispersant in the preparation of the inorganic solid electrolyte composition is determined by its combination with the dispersant, rather than by a blanket determination.

[0317] Typically, in compositions containing inorganic solid electrolytes, the compound with the highest content, besides the inorganic solid electrolyte, active material, and conductive additives, becomes the dispersion medium.

[0318] Examples of alcohol compounds include, for example, methanol, ethanol, 1-propanol, 2-propanol, 2-butanol, ethylene glycol, propylene glycol, glycerol, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, 2-methyl-2,4-pentanediol, 1,3-butanediol, and 1,4-butanediol.

[0319] Examples of ether compounds include alkylene glycols (diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, etc.), alkylene glycol monoalkyl ethers (ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, etc.), alkylene glycol dialkyl ethers (ethylene glycol dimethyl ether, etc.), dialkyl ethers (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), and cyclic ethers (tetrahydrofuran, dioxanes (including 1,2-, 1,3- and 1,4- isomers, etc.)).

[0320] Examples of amide compounds include, for example, N,N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolinone, ε-caprolactam, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropaneamide, hexamethylphosphoric triamide, etc.

[0321] Examples of amine compounds include triethylamine, diisopropylethylamine, and tri-n-butylamine.

[0322] 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, butylpropyl ketone, etc.

[0323] Examples of aromatic compounds include, for example, benzene, toluene, and xylene.

[0324] Examples of aliphatic compounds include hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, decahydronaphthalene, paraffin wax, gasoline, naphtha, kerosine, kerosene, and light oil.

[0325] Examples of nitrile compounds include acetonitrile, propionitrile, and isobutyronitrile.

[0326] Examples of ester compounds include, for example, ethyl acetate, propyl acetate, butyl acetate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, butyl valerate, pentyl valerate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, isobutyl isobutyrate, propyl neovalerate, isopropyl neovalerate, butyl neovalerate, isobutyl neovalerate, etc.

[0327] In this invention, ether compounds, ketone compounds, aromatic compounds, aliphatic compounds, and ester compounds are preferred, and ester compounds, ketone compounds, or ether compounds are more preferred.

[0328] There is no particular limitation on the number of carbon atoms in the compound constituting the dispersion medium, but it is preferably 2 to 30, more preferably 4 to 20, even more preferably 6 to 15, and especially preferably 7 to 12.

[0329] From the perspective of dispersion characteristics, the SP value (unit: MPa) of the dispersion medium 1 / 2 The preferred concentration is 15.0–21.0, more preferably 16.0–20.0, and even more preferably 17.0–19.0. The difference in SP value between the above dispersant and the dispersion medium (absolute value, unit: MPa) 1 / 2 There are no particular limitations, but from the viewpoint of further improving dispersion characteristics and coating suitability, it is preferable to be 3.0 or less, more preferably 0 to 2.5, further preferably 0 to 2.0, particularly preferably 0 to 1.0, and most preferably 0 to 0.5. When multiple dispersants are contained, the difference (absolute value) of SP values ​​is preferably the minimum value (absolute value) included in the above range, or all differences (absolute values) may be included in the above range.

[0330] The SP value of the dispersion medium is set to be the SP value calculated by the Hoy method described above, converted to MPa. 1 / 2 The SP value is obtained as follows. When the inorganic solid electrolyte composition contains two or more dispersion media, the SP value of the dispersion media refers to the SP value of the entire dispersion media, and is set as the sum of the products of the SP value of each dispersion media and its mass fraction. Specifically, except that the SP value of each dispersion media is used instead of the SP value of the constituent components, it is calculated in the same way as the SP value of the polymer described above.

[0331] The SP values ​​(units omitted) of the dispersion medium are shown in parentheses after the specific compound name below.

[0332] MIBK (18.4), diisopropyl ether (16.8), dibutyl ether (17.9), diisobutyl ketone (17.9), DIBK (17.9), butyl butyrate (18.6), butyl acetate (18.9), toluene (18.5), ethylcyclohexane (17.1), cyclooctane (18.8), isobutyl ethyl ether (15.3), N-methylpyrrolidone (NMP, SP value: 25.4)

[0333] The inorganic solid electrolyte composition of the present invention may contain at least one dispersion medium, or more than two.

[0334] In this invention, the content of the dispersion medium in the inorganic solid electrolyte composition is not particularly limited, but is set within the range that satisfies the above-mentioned concentration of solid components.

[0335] <Active Substances>

[0336] The inorganic solid electrolyte composition of the present invention may also contain an active material capable of intercalating or deintercalating ions of metals belonging to Group 1 or Group 2 of the periodic table. Examples of active materials, including positive electrode active materials and negative electrode active materials, will be described below.

[0337] In this invention, an inorganic solid electrolyte composition containing an active material (positive electrode active material or negative electrode active material) is sometimes referred to as an electrode composition (positive electrode composition or negative electrode composition).

[0338] (Positive electrode active material)

[0339] The positive electrode active material is preferably a positive electrode active material capable of reversibly inserting and deintercalating lithium ions. There are no particular restrictions as long as the material has the above-mentioned characteristics, and it can be a transition metal oxide of the decomposition battery or an element that can recombine with Li, such as sulfur.

[0340] Among them, transition metal oxides are preferred as positive electrode active materials, and more preferably materials containing the transition metal element M. a A transition metal oxide (selected from one or more elements including Co, Ni, Fe, Mn, Cu, and V). Furthermore, element M may also be mixed into this transition metal oxide. b (Elements of Group 1(Ia) and Group 2(IIa) of the periodic table, excluding lithium, and elements such as Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B). As a mixing amount, it is preferable to be relative to the transition metal element M. a The amount (100 mol%) is 0-30 mol%. More preferably, it is Li / M a They are synthesized by mixing in a molar ratio of 0.3 to 2.2.

[0341] Specific examples of transition metal oxides include (MA) transition metal oxides with a layered rock salt structure, (MB) transition metal oxides with a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD) lithium-containing transition metal halophosphate compounds, and (ME) lithium-containing transition metal silicate compounds.

[0342] Specific examples of transition metal oxides (MA) with layered rock salt-type structures include LiCoO2 (lithium cobalt oxide [LCO]), LiNi2O2 (lithium nickel oxide), and LiNi 0.85 Co 0.10 Al 0.05 O2 (lithium nickel cobalt aluminum oxide [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn0.5 O2 (lithium manganese nickel oxide).

[0343] Specific examples of transition metal oxides (MB) with spinel-type structures include LiMn2O4 (LMO), LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8, and Li2NiMn3O8.

[0344] Examples of lithium-containing transition metal phosphates (MC) include olivine-type iron phosphates such as LiFePO4 and Li3Fe2(PO4)3, iron pyrophosphates such as LiFeP2O7, cobalt phosphates such as LiCoPO4, and monoclinic NASICON-type vanadium phosphates such as Li3V2(PO4)3 (lithium vanadium phosphate).

[0345] Examples of lithium-containing transition metal halophosphates (MD) include, for example, iron fluorophosphates such as Li2FePO4F, manganese fluorophosphates such as Li2MnPO4F, and cobalt fluorophosphates such as Li2CoPO4F.

[0346] Examples of lithium-containing transition metal silicate compounds include, for example, Li2FeSiO4, Li2MnSiO4, and Li2CoSiO4.

[0347] In this invention, (MA) is preferably a transition metal oxide having a layered rock salt structure, and more preferably LCO or NMC.

[0348] The shape of the positive electrode active material is not particularly limited, but particulate form is preferred. The particle size (volume average particle size) of the positive electrode active material is not particularly limited. For example, it can be set to 0.1–50 μm. The particle size of the positive electrode active material can be measured in the same manner as the particle size of the aforementioned inorganic solid electrolyte. To achieve the desired particle size, a conventional pulverizer or classifier is used. For example, a mortar, ball mill, sand mill, vibratory ball mill, satellite ball mill, planetary ball mill, and rotary airflow jet mill or sieve can be suitably used. During pulverization, wet pulverization with a dispersion medium such as water or methanol can also be appropriately performed. To achieve the desired particle size, classification is preferred. Classification is not particularly limited and can be performed using sieves, air classifiers, etc. Both dry and wet classification can be used.

[0349] Positive active materials obtained by sintering can also be used after being cleaned with water, acidic aqueous solutions, alkaline aqueous solutions, and organic solvents.

[0350] When the inorganic solid electrolyte composition of the present invention contains a positive electrode active material, the positive electrode active material may be one type or two or more types.

[0351] When a positive electrode active material layer is formed, the per unit area (cm²) of the positive electrode active material layer... 2 There is no particular limitation on the mass (mg) (weight per unit area) of the positive electrode active material. It can be appropriately determined according to the designed battery capacity, for example, it can be set to 1 to 100 mg / cm³. 2 .

[0352] The content of the positive electrode active material in the inorganic solid electrolyte composition is not particularly limited, but it is preferably 10-97% by mass, more preferably 30-95% by mass, further preferably 40-93% by mass, and especially preferably 50-90% by mass in 100% by mass of the solid component.

[0353] (Negative electrode active material)

[0354] The preferred negative electrode active material is one capable of reversibly inserting and deintercalating lithium ions. There are no particular limitations on the material as long as it possesses the aforementioned properties; examples include carbonaceous materials, metal oxides, metal composite oxides, lithium monomers, lithium alloys, and negative electrode active materials capable of forming alloys with lithium. From a reliability perspective, carbonaceous materials, metal composite oxides, or lithium monomers are preferred. From the perspective of maximizing the capacity of all-solid-state secondary batteries, negative electrode active materials capable of alloying with lithium are preferred.

[0355] Carbonaceous materials used as negative electrode active materials refer to materials that are essentially composed of carbon. Examples include carbonaceous materials produced by sintering petroleum asphalt, carbon black such as acetylene black (AB), graphite (natural graphite, vapor-grown graphite, and other artificial graphite), and 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 planar graphite.

[0356] These carbonaceous materials are classified into non-graphitized carbonaceous materials (also known as hard carbon) and graphite-based carbonaceous materials based on the degree of graphitization. Furthermore, the carbonaceous materials preferably possess the facet spacing or density and crystallite size described in Japanese Patent Application Publication Nos. 62-22066, 2-6856, and 3-45473. The carbonaceous material need not be a single material; mixtures of natural and artificial graphite as described in Japanese Patent Application Publication No. 5-90844, or coated graphite as described in Japanese Patent Application Publication No. 6-4516, etc., can also be used.

[0357] As a carbonaceous material, hard carbon or graphite is preferred, with graphite being more preferred.

[0358] As oxides of metals or half-metals suitable as negative electrode active materials, there are no particular limitations as long as they are oxides capable of absorbing and releasing lithium. Examples include oxides of metal elements (metal oxides), composite oxides of metal elements, or composite oxides of metal elements and half-metal elements (collectively referred to as metal composite oxides), and oxides of half-metal elements (half-metal oxides). Among these oxides, amorphous oxides are preferred, and further preferred are chalcogenides, products of the reaction between metal elements and elements of Group 16 of the periodic table. In this invention, a half-metal element refers to an element exhibiting intermediate properties between a metal element and a non-half-metal element, typically including six elements: boron, silicon, germanium, arsenic, antimony, and tellurium, and further including three elements: selenium, polonium, and astatine. Furthermore, amorphous refers to a material having a broad scattering band with vertices in the region of 20° to 40° at 2θ values ​​using X-ray diffraction with CuKα rays, and may also have crystalline diffraction lines. The strongest intensity of the crystalline diffraction lines appearing in the region of 40° to 70° at a 2θ value is preferably 100 times or less than the intensity of the diffraction line at the apex of the broad scattering band appearing in the region of 20° to 40° at a 2θ value, more preferably 5 times or less, and especially preferably a non-crystalline diffraction line.

[0359] Among the compounds comprising the aforementioned amorphous oxides and chalcogenides, amorphous oxides of half-metallic elements or the aforementioned chalcogenides are more preferred, and (composite) oxides or chalcogenides comprising one or more elements selected from groups 13(IIIB) to 15(VB) of the periodic table (e.g., Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) are particularly preferred. Specific examples of preferred amorphous oxides and chalcogenides include, for example, Ga₂O₃, GeO, PbO, PbO₂, Pb₂O₃, Pb₂O₄, Pb₃O₄, Sb₂O₄, Sb₂O₈Bi₂O₃, Sb₂O₈Si₂O₃, Sb₂O₅, Bi₂O₃, Bi₂O₄, GeS, PbS, PbS₂, Sb₂S₃, or Sb₂S₅.

[0360] As a negative electrode active material that can be used with amorphous oxides centered on Sn, Si, and Ge, carbonaceous materials, lithium monomers, lithium alloys, and negative electrode active materials that can be alloyed with lithium are preferred examples.

[0361] From the viewpoint of high current density charge and discharge characteristics, oxides of metal or half-metal elements, especially metal (composite) oxides and the aforementioned 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 with the aforementioned metal (composite) oxides or chalcogenides; more specifically, Li₂SnO₂ can be cited.

[0362] Negative electrode active materials, such as metal oxides, are preferably those containing titanium (titanium oxide). Specifically, due to Li4Ti5O 12 Lithium titanate (LTO) exhibits minimal volume change during lithium ion adsorption and deintercalation, resulting in excellent rapid charge and discharge characteristics. It is preferred in terms of both suppressing electrode degradation and improving the lifespan of lithium-ion secondary batteries.

[0363] There are no particular restrictions on the lithium alloy used as the negative electrode active material, as long as it is an alloy commonly used as the negative electrode active material in secondary batteries. For example, lithium-aluminum alloys can be cited. Specifically, lithium-aluminum alloys can be cited, which are made by adding 10% by mass of aluminum to lithium as the base metal.

[0364] There are no particular limitations on the negative electrode active material that can form an alloy with lithium, as long as it is a negative electrode active material commonly used in secondary batteries. Because such active materials experience large expansion and contraction during charging and discharging in all-solid-state secondary batteries, which accelerates the decline in cycle characteristics, the all-solid-state secondary battery of the present invention, in which a layer composed of the inorganic solid electrolyte composition of the present invention is assembled, can suppress the decline in cycle characteristics. Examples of such active materials include (negative electrode) active materials (alloys, etc.) containing silicon or tin, various metals such as Al and In, preferably negative electrode active materials containing silicon (silicon-containing active materials) that can achieve higher battery capacity, and more preferably silicon-containing active materials where the silicon content is 50 mol% or more of all constituent elements.

[0365] Generally, negative electrodes containing these active materials (such as Si negative electrodes containing silicon-containing active materials and Sn negative electrodes containing tin-containing active materials) can absorb more Li ions compared to carbon negative electrodes (such as graphite and acetylene black). That is, the amount of Li ions retained per unit mass increases. Therefore, the battery capacity can be increased. As a result, it has the advantage of extending battery operating time.

[0366] Examples of silicon-containing active materials include silicon materials such as Si and SiOx (0 < x ≤ 1), as well as silicon-containing alloys (e.g., LaSi2, VSi2, La-Si, Gd-Si, Ni-Si) or structured active materials (e.g., LaSi2 / Si) containing elements such as titanium, vanadium, chromium, manganese, nickel, copper, and lanthanum. Additionally, active materials containing silicon elements such as SnSiO3 and SnSiS3, and tin elements, are also included. Furthermore, SiOx can be used as a negative electrode active material (a half-metal oxide) itself, and since Si is generated 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.

[0367] Examples of anode active materials containing tin include those containing Sn, SnO, SnO2, SnS, SnS2, and the aforementioned silicon and tin elements. Furthermore, composite oxides with lithium oxide, such as Li2SnO2, can also be cited.

[0368] In this invention, the above-mentioned negative electrode active material can be used without particular limitation. However, from the viewpoint of battery capacity, it is preferable to use a negative electrode active material that can be alloyed with lithium. More preferably, it is the above-mentioned silicon material or silicon-containing alloy (an alloy containing silicon element). It is even more preferably to contain silicon (Si) or a silicon-containing alloy.

[0369] As a determination method, inductively coupled plasma (ICP) emission spectroscopy can be used. As a simple method, the chemical formula of the compound obtained by the above-mentioned firing method can be calculated from the mass difference of the powder before and after firing.

[0370] The shape of the negative electrode active material is not particularly limited, but particulate form is preferred. The particle size (volume average particle size) of the negative electrode active material is not particularly limited, but is preferably 0.1–60 μm. The particle size of the negative electrode active material can be measured in the same manner as that of the inorganic solid electrolyte described above. To achieve the specified particle size, a conventional pulverizer or classifier is used, similar to that used for the positive electrode active material.

[0371] When the inorganic solid electrolyte composition of the present invention contains a negative electrode active material, the negative electrode active material may be one type or two or more types.

[0372] When a negative electrode active material layer is formed, the per unit area (cm²) of the negative electrode active material layer... 2 There is no particular limitation on the mass (mg) (weight per unit area) of the negative electrode active material. It can be appropriately determined according to the designed battery capacity, for example, it can be set to 1 to 100 mg / cm³. 2 .

[0373] The content of the negative electrode active material in the inorganic solid electrolyte composition is not particularly limited, but is preferably 10-90% by mass, more preferably 20-85% by mass, more preferably 30-80% by mass, and even more preferably 40-75% by mass in 100% by mass of solid components.

[0374] In this invention, when the negative electrode active material layer is formed by charging a secondary battery, ions belonging to Group 1 or Group 2 of the periodic table metal generated within the all-solid-state secondary battery can be used instead of the aforementioned negative electrode active material. By bonding these ions with electrons and depositing them as metal, the negative electrode active material layer can be formed.

[0375] (Coating of active substances)

[0376] The surfaces of both the positive and negative electrode active materials can be coated with different metal oxides. Examples of surface coating agents include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specifically, examples include spinel titanate, tantalum oxides, niobium oxides, and lithium niobate compounds; for instance, Li₄Ti₅O₅ can be used. 12 , Li2Ti2O5, LiTaO3, LiNbO3, LiAlO2, Li2ZrO3, Li2WO4, Li2TiO3, Li2B4O7, Li3PO4, Li2MoO4, Li3BO3, LiBO2, Li2CO3, Li2SiO3, SiO2, TiO2, ZrO2, Al2O3, B2O3, etc.

[0377] Furthermore, the electrode surface containing positive or negative active materials can be surface-treated with sulfur or phosphorus.

[0378] Furthermore, the particle surface of the positive or negative active material can be surface-treated by photochemical rays or active gas (plasma, etc.) before and after the aforementioned surface coating.

[0379] <Conductive additives>

[0380] The inorganic solid electrolyte composition of the present invention preferably contains a conductive additive. For example, the silicon-containing active material as the negative electrode active material is preferably used in combination with the conductive additive.

[0381] There are no particular restrictions on the conductive additives used; any conductive additives known to be used as conductive additives can be used. For example, these can be graphite materials such as natural graphite and artificial graphite, carbon blacks such as acetylene black (AB), Ketjen black, and furnace black, amorphous carbon such as needle coke, carbon fibers such as vapor-grown carbon fibers or carbon nanotubes, carbonaceous materials such as graphene or fullerene, metal powders such as copper and nickel, metal fibers, or conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives.

[0382] In this invention, when active materials and conductive additives are used in combination, the conductive additives that do not produce the insertion and extraction of metal ions (preferably Li ions) belonging to Group 1 or Group 2 of the periodic table during battery charging and discharging, and do not function as active materials, are classified as conductive additives. Therefore, among conductive additives, those that can function as active materials in the active material layer during battery charging and discharging are classified as active materials rather than conductive additives. Whether an additive functions as an active material during battery charging and discharging is determined by its combination with active materials, rather than by a general rule.

[0383] There are no particular restrictions on the shape of the conductive additive, but it is preferably in particulate form.

[0384] When the inorganic solid electrolyte composition of the present invention contains a conductive additive, the conductive additive may be one type or two or more types.

[0385] When the inorganic solid electrolyte composition contains a conductive additive, the content of the conductive additive in the composition containing the inorganic solid electrolyte is preferably more than 0 and less than 10% by mass in 100% by mass of the solid component.

[0386] <Lithium Salts>

[0387] The inorganic solid electrolyte composition of the present invention preferably also contains a lithium salt (supporting electrolyte).

[0388] As a lithium salt, the lithium salt commonly used in this product is preferred, and there are no particular limitations. For example, the lithium salt described in paragraphs 0082 to 0085 of Japanese Patent Application Publication No. 2015-088486 is preferred.

[0389] When the inorganic solid electrolyte composition of the present invention contains a lithium salt, the content of the lithium salt relative to 100 parts by weight of the inorganic solid electrolyte is preferably 0.1 parts by weight or more, more preferably 5 parts by weight or more. As an upper limit, it is preferably 50 parts by weight or less, more preferably 20 parts by weight or less.

[0390] <Other Additives>

[0391] The inorganic solid electrolyte composition of the present invention can appropriately contain ionic liquids, thickeners, crosslinking agents (substances that undergo crosslinking reactions via free radical polymerization, condensation polymerization, or ring-opening polymerization, etc.), polymerization initiators (substances that generate acids or free radicals through heat or light, etc.), defoamers, homogenizers, dehydrating agents, antioxidants, etc., as other components besides those mentioned above. Ionic liquids are liquids contained to further improve ionic conductivity, and known liquids can be used without particular limitation. Furthermore, it can contain the aforementioned dispersants, polymers other than those constituting polymer binders, commonly used adhesives, etc.

[0392] (Preparation of inorganic solid electrolyte compositions)

[0393] The inorganic solid electrolyte composition of the present invention can be prepared by conventional methods. Specifically, it can be prepared, for example, by mixing an inorganic solid electrolyte, a dispersant and dispersion medium, preferably a polymer binder, a conductive agent, and a suitable lithium salt, and any other components, as a mixture, preferably as a slurry, using various commonly used mixers. In the case of the electrode composition, an active material is further mixed in.

[0394] There are no particular restrictions on the mixing method; any known mixer, such as a ball mill, bead mill, planetary mixer, scraper mixer, roller mill, kneader, disc pulverizer, rotation-revolution mixer, or narrow-gap disperser, can be used.

[0395] There are no particular limitations on the mixing conditions. For example, the rotation speed of a rotation-revolution mixer can be set to 200–3000 rpm. The mixing atmosphere can be any atmosphere, including atmospheric pressure, dry air (dew point below -20°C), and inert gases (e.g., argon, helium, nitrogen). Since inorganic solid electrolytes readily react with moisture, mixing under dry air or an inert gas is preferred.

[0396] [Sheets for all-solid-state rechargeable batteries]

[0397] The sheet material for all-solid-state secondary batteries of the present invention is a sheet-shaped molded body capable of forming the constituent layers of an all-solid-state secondary battery, and includes various forms depending on its application. For example, sheets preferably used for solid electrolyte layers (also called solid electrolyte sheets for all-solid-state secondary batteries) and sheets preferably used for electrodes or laminates of electrodes and solid electrolyte layers (electrode sheets for all-solid-state secondary batteries) are examples. In the present invention, these various sheets are collectively referred to as sheets for all-solid-state secondary batteries.

[0398] In this invention, each layer constituting the sheet for all-solid-state secondary batteries can be a single-layer structure or a multi-layer structure.

[0399] Solid electrolyte sheets for all-solid-state secondary batteries

[0400] The solid electrolyte sheet for all-solid-state secondary batteries of the present invention can be any sheet having a solid electrolyte layer. It can be a sheet with the solid electrolyte layer formed on a substrate, or it can be a sheet without a substrate, formed solely by the solid electrolyte layer. In addition to the solid electrolyte layer, the solid electrolyte sheet for all-solid-state secondary batteries may also have other layers. Examples of other layers include, for instance, a protective layer (release sheet), a current collector, and a coating.

[0401] As an example of the solid electrolyte sheet for an all-solid-state secondary battery according to the present invention, a sheet having, in sequence, a layer composed of the inorganic solid electrolyte composition of the present invention, a conventional solid electrolyte layer, and a protective layer on a substrate is exemplified. The layer thickness of each layer constituting the solid electrolyte sheet for an all-solid-state secondary battery is the same as the layer thickness described later in the description of all-solid-state secondary batteries.

[0402] The content of each component in the constituent layer is not particularly limited, and the preferred meaning is the same as the meaning of the content of each component in the solid component of the inorganic solid electrolyte composition of the present invention. However, during the fabrication of the layer or battery, at least a portion of the dispersant in the inorganic solid electrolyte composition may volatilize or evaporate. In this case, the content of each component other than the dispersant in the constituent layer is preferably the same as the meaning of the content of each component other than the dispersant in the dispersion medium of the inorganic solid electrolyte composition of the present invention.

[0403] As for the substrate, there are no particular limitations as long as it is a substrate capable of supporting the solid electrolyte layer. Examples include sheet-like materials (plate-like bodies) such as those described in the current collector section (described later), organic materials, and inorganic materials. Examples of organic materials include various polymers, specifically polyethylene terephthalate, polypropylene, polyethylene, and cellulose. Examples of inorganic materials include, for example, glass and ceramics.

[0404] <Electrode sheets for all-solid-state secondary batteries>

[0405] The electrode sheet for all-solid-state secondary batteries of the present invention (also simply referred to as "electrode sheet") can be any electrode sheet having an active material layer. It can be a sheet in which the active material layer is formed on a substrate (current collector), or it can be a sheet formed by the active material layer without a substrate. The electrode sheet is usually a sheet having a substrate (current collector) and an active material layer, but it also includes forms having a substrate (current collector), an active material layer and a solid electrolyte layer in sequence, as well as forms having a substrate (current collector), an active material layer, a solid electrolyte layer and an active material layer in sequence.

[0406] At least one of the solid electrolyte layer and the active material layer of the electrode sheet is formed from the inorganic solid electrolyte composition of the present invention. The content of each component in the solid electrolyte layer or the active material layer formed from the inorganic solid electrolyte composition of the present invention is not particularly limited, and the preferred meaning has the same meaning as the content of each component in the solid components of the inorganic solid electrolyte composition (electrode composition) of the present invention. The layer thickness of each layer constituting the electrode sheet of the present invention is the same as the layer thickness described later in the description of all-solid-state secondary batteries. The electrode sheet of the present invention may have the other layers described above.

[0407] In addition, when the solid electrolyte layer or active material layer is not formed by the inorganic solid electrolyte composition of the present invention, it is formed by a conventional constituent layer forming material.

[0408] In the all-solid-state secondary battery sheet of the present invention, at least one of the solid electrolyte layer and the active material layer is formed from the inorganic solid electrolyte composition of the present invention, and has a surface-flat constituent layer formed by firmly bonding solid particles together. Therefore, the all-solid-state secondary battery sheet of the present invention, when used as a constituent layer of an all-solid-state secondary battery, enables the achievement of excellent cycle characteristics of the all-solid-state secondary battery. In particular, in the all-solid-state secondary battery electrode sheet and the all-solid-state secondary battery in which the active material layer is formed from the inorganic solid electrolyte composition of the present invention, the active material layer and the current collector exhibit strong adhesion, which further improves the cycle characteristics. Therefore, the all-solid-state secondary battery sheet of the present invention is suitable for use as a sheet capable of forming a constituent layer of an all-solid-state secondary battery.

[0409] [Manufacturing Method of Sheets for All-Solid-State Secondary Batteries]

[0410] The manufacturing method of the all-solid-state secondary battery sheet of the present invention is not particularly limited, and it can be manufactured by forming the above-mentioned layers using the inorganic solid electrolyte composition of the present invention. For example, a method is preferably used to form a layer (coating-drying layer) composed of the inorganic solid electrolyte composition by film formation (coating-drying) on ​​a substrate or current collector (which may be via another layer). This allows the production of an all-solid-state secondary battery sheet having a substrate or current collector and a coating-drying layer. In particular, when the all-solid-state secondary battery sheet is produced by film formation of the inorganic solid electrolyte composition of the present invention on a current collector, the adhesion between the current collector and the active material layer becomes stronger. Here, the coating-drying layer refers to a layer formed by coating the inorganic solid electrolyte composition of the present invention and drying the dispersion medium (i.e., a layer formed using the inorganic solid electrolyte composition of the present invention, and composed of a composition from which the dispersion medium is removed). The dispersion medium may remain in the active material layer and the coating-drying layer as long as it does not impair the effects of the present invention; the residual amount can be, for example, 3% by mass or less in each layer.

[0411] In the manufacturing method of the all-solid-state secondary battery sheet of the present invention, each step such as coating and drying will be described in the following manufacturing method of the all-solid-state secondary battery.

[0412] In the method for manufacturing the sheet material for all-solid-state secondary batteries of the present invention, the coated and dried layer obtained in the above manner can also be pressurized. The pressurization conditions, etc., will be explained in the manufacturing method for all-solid-state secondary batteries described later.

[0413] Furthermore, in the manufacturing method of the all-solid-state secondary battery sheet of the present invention, it is also possible to peel off the substrate, protective layer (especially the sheet), etc.

[0414] [All-solid-state rechargeable battery]

[0415] The all-solid-state secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer opposite to 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 only required to have a structure with a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer; other structures are not particularly limited, for example, known structures related to all-solid-state secondary batteries can be used. In a preferred all-solid-state secondary battery, a positive electrode current collector is stacked on the surface of the positive electrode active material layer opposite to the solid electrolyte layer to form a positive electrode, and a negative electrode current collector is stacked on the surface of the negative electrode active material layer opposite to the solid electrolyte layer to form a negative electrode. In the present invention, each constituent layer (including the current collector, etc.) constituting the all-solid-state secondary battery can be a single-layer structure or a multi-layer structure.

[0416] In the all-solid-state secondary battery of the present invention, at least one of the negative electrode active material layer, the positive electrode active material layer, and the solid electrolyte layer is a layer formed by the inorganic solid electrolyte composition of the present invention, exhibiting excellent cycle characteristics. From the viewpoint of further improving cycle characteristics, it is preferable that at least two of the negative electrode active material layer, the positive electrode active material layer, and the solid electrolyte layer are formed by the inorganic solid electrolyte composition of the present invention; more preferably, all of the negative electrode active material layer, the positive electrode active material layer, and the solid electrolyte layer are formed by the inorganic solid electrolyte composition of the present invention. In the present invention, the constituent layer of the all-solid-state secondary battery formed by the inorganic solid electrolyte composition of the present invention refers to a constituent layer formed by a sheet for the all-solid-state secondary battery of the present invention (wherein, a sheet obtained by removing layers other than those formed by the inorganic solid electrolyte composition of the present invention). Regarding the types and contents of the components contained, the active material layer or solid electrolyte layer formed by the inorganic solid electrolyte composition of the present invention is preferably the same as the solid component in the inorganic solid electrolyte composition of the present invention.

[0417] <Active Material Layer and Solid Electrolyte Layer>

[0418] There are no particular limitations on the thickness of the negative electrode active material layer, the solid electrolyte layer, and the positive electrode active material layer. Considering the size of a typical all-solid-state secondary battery, the thickness of each layer is preferably 10 to 1,000 μm, more preferably 20 μm or more and less than 500 μm. In the all-solid-state secondary battery of the present invention, the thickness of at least one of the positive electrode active material layer and the negative electrode active material layer is further preferably 50 μm or more and less than 500 μm.

[0419] Furthermore, when the active material layer or solid electrolyte layer is not formed from the inorganic solid electrolyte composition of the present invention, known materials can be used.

[0420] <Current Collector>

[0421] The positive and negative current collectors are preferably electron conductors.

[0422] In this invention, either the positive current collector or the negative current collector, or both of them together, are sometimes referred to simply as a current collector.

[0423] In addition to aluminum, aluminum alloys, stainless steel, nickel, and titanium, materials in which carbon, nickel, titanium, or silver (materials forming thin films) are treated on the surface of aluminum or stainless steel are preferred as the material forming the positive current collector. Among these, aluminum and aluminum alloys are more preferred.

[0424] In addition to aluminum, copper, copper alloys, stainless steel, nickel, and titanium, materials that have been treated with carbon, nickel, titanium, or silver on the surface of aluminum, copper, copper alloys, or stainless steel are preferred as materials for forming the negative current collector. More preferably, aluminum, copper, copper alloys, and stainless steel are preferred.

[0425] Current collectors are typically in the form of a membrane, but can also be made of mesh, perforated material, lath, porous material, foam, or fiber assembly.

[0426] There is no particular limitation on the thickness of the current collector, but it is preferably 1 to 500 μm. Furthermore, it is also preferable to have irregularities on the surface of the current collector through surface treatment.

[0427] <Other Structures>

[0428] In this invention, functional layers or components may be appropriately inserted or disposed between or on the outside of the layers of the negative electrode current collector, the negative electrode active material layer, the solid electrolyte layer, the positive electrode active material layer, and the positive electrode current collector.

[0429] <Shell>

[0430] The all-solid-state secondary battery of the present invention can be used as an all-solid-state secondary battery in the above-described structural state depending on the application, but in order to make it into a dry cell form, it is preferable to further enclose it in a suitable casing. The casing can be a metallic casing or a resin (plastic) casing. When using a metallic casing, for example, a casing made of aluminum alloy or stainless steel can be cited. Preferably, the metallic casing is divided into a positive electrode side casing and a negative electrode side casing, which are electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. Preferably, the positive electrode side casing and the negative electrode side casing are joined together as one piece with a short-circuit prevention gasket.

[0431] The following is for reference. Figure 1 The preferred embodiments of the present invention will be described, but the present invention is not limited thereto.

[0432] Figure 1 This is a schematic cross-sectional view illustrating a preferred embodiment of the all-solid-state secondary battery (lithium-ion secondary battery) of the present invention. Viewed from the negative electrode side, the all-solid-state secondary battery 10 of this embodiment sequentially comprises 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. Each layer is in contact with the others and has an adjacent structure. By employing such a structure, electrons (electrons) are supplied to the negative electrode side during charging. - ), and accumulate lithium ions (Li) here. + On the other hand, during discharge, lithium ions (Li) accumulated at the negative electrode... + The electrons return to the positive side and supply electrons to the working part 6. In the illustrated example, a light bulb is used as a model in the working part 6, and the bulb is lit by discharging.

[0433] In having Figure 1 When the layered solid-state secondary battery shown is placed in a 2032-type button cell, the solid-state secondary battery is sometimes referred to as a laminate for solid-state secondary batteries. The battery made by placing the laminate for solid-state secondary batteries in a 2032-type button cell is called a (button-type) solid-state secondary battery.

[0434] (Positive electrode active material layer, solid electrolyte layer, negative electrode active material layer)

[0435] In the all-solid-state secondary battery 10, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are all formed from the inorganic solid electrolyte composition of the present invention. This all-solid-state secondary battery 10 exhibits excellent battery performance. The inorganic solid electrolyte and dispersant contained in the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 can be of the same type or different types.

[0436] In this invention, either or both of the positive electrode active material layer and the negative electrode active material layer are simply referred to as the active material layer or the electrode active material layer. Furthermore, either or both of the positive electrode active material and the negative electrode active material are collectively referred to as the active material or the electrode active material.

[0437] In this invention, when the constituent layer is formed by the inorganic solid electrolyte composition of this invention, an all-solid-state secondary battery with excellent cycle characteristics can be realized.

[0438] In the all-solid-state secondary battery 10, the negative electrode active material layer can be a lithium metal layer. Examples of lithium metal layers include layers formed by stacking or molding lithium metal powder, lithium foil, and lithium vapor-deposited films. The thickness of the lithium metal layer is independent of the thickness of the negative electrode active material layer, and for example, can be set to 1 to 500 μm.

[0439] (Current collector)

[0440] The positive current collector 5 and the negative current collector 1 are as described above.

[0441] In the all-solid-state secondary battery 10 described above, when it has a constituent layer other than the constituent layer formed by the inorganic solid electrolyte composition of the present invention, a layer formed by a known constituent layer forming material can also be used.

[0442] Furthermore, each layer can be a single layer or multiple layers.

[0443] [Manufacturing of all-solid-state rechargeable batteries]

[0444] All-solid-state secondary batteries can be manufactured using conventional methods. Specifically, all-solid-state secondary batteries can be manufactured by forming the aforementioned layers using the inorganic solid electrolyte composition of the present invention. This will be described in detail below.

[0445] The all-solid-state secondary battery of the present invention can be manufactured by performing a method (the method for manufacturing the sheet for all-solid-state secondary battery of the present invention) that includes a step of forming a coating film by appropriately coating the inorganic solid electrolyte composition of the present invention onto a substrate (e.g., a metal foil that serves as a current collector).

[0446] For example, a positive electrode active material layer is formed by coating an inorganic solid electrolyte composition containing a positive electrode active material as a positive electrode material (positive electrode composition) onto a metal foil serving as the positive electrode current collector to create a positive electrode sheet for an all-solid-state secondary battery. Next, an inorganic solid electrolyte composition for forming a solid electrolyte layer is coated onto this positive electrode active material layer to form a solid electrolyte layer. Furthermore, an inorganic solid electrolyte composition containing a negative electrode active material as a negative electrode material (negative electrode composition) is coated onto the solid electrolyte layer to form a negative electrode active material layer. By overlapping a negative electrode current collector (metal foil) onto the negative electrode active material layer, an all-solid-state secondary battery with a structure in which the solid electrolyte layer is sandwiched between the positive and negative electrode active material layers can be obtained. It can also be encapsulated in a casing to form a desired all-solid-state secondary battery.

[0447] Furthermore, in contrast to the methods for forming each layer, it is also possible to manufacture an all-solid-state secondary battery by forming a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer on the negative electrode current collector and then overlapping the positive electrode current collector.

[0448] As another method, the following approach can be used: The positive electrode sheet for an all-solid-state secondary battery is manufactured as described above. Furthermore, an inorganic solid electrolyte composition containing negative electrode active material is coated onto a metal foil serving as the negative electrode current collector to form a negative electrode active material layer, thereby manufacturing the negative electrode sheet for an all-solid-state secondary battery. Next, a solid electrolyte layer is formed on the active material layer of any one of these sheets, as described above. Then, the positive electrode sheet for an all-solid-state secondary battery and another negative electrode sheet for an all-solid-state secondary battery are stacked on the solid electrolyte layer in such a way 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.

[0449] Furthermore, as another method, the following can be cited: That is, to manufacture the positive electrode sheet and the negative electrode sheet for an all-solid-state secondary battery as described above. In addition, a solid electrolyte sheet for an all-solid-state secondary battery, consisting of a solid electrolyte layer, is manufactured by coating an inorganic solid electrolyte composition onto a substrate. Moreover, the solid electrolyte layer, which has been peeled off from the substrate, is stacked in a manner where the positive electrode sheet and the negative electrode sheet for an all-solid-state secondary battery hold it in place. In this way, an all-solid-state secondary battery can be manufactured.

[0450] Furthermore, as described above, a positive electrode sheet, a negative electrode sheet, and a solid electrolyte sheet for an all-solid-state secondary battery are manufactured. Next, the positive or negative electrode active material layer and the solid electrolyte sheet are overlapped and pressurized. This transfers the solid electrolyte layer onto the positive or negative electrode sheet. Then, the solid electrolyte layer obtained by peeling off the substrate of the solid electrolyte sheet is overlapped with the negative or positive electrode sheet (while the negative or positive electrode active material layer is in contact with the solid electrolyte layer) and pressurized. In this way, an all-solid-state secondary battery can be manufactured. The pressing method and conditions in this method are not particularly limited, and the methods and conditions described in the pressing process described later can be used.

[0451] Solid electrolyte layers, for example, can also be formed by pressure molding under pressure conditions described later on a substrate or active material layer to form an inorganic solid electrolyte composition, and sheet molded articles of solid electrolytes or active materials can also be used.

[0452] In the above manufacturing method, the inorganic solid electrolyte composition of the present invention can be used in any one of the positive electrode composition, the inorganic solid electrolyte composition, and the negative electrode composition, or the inorganic solid electrolyte composition of the present invention can be used in any composition.

[0453] When a solid electrolyte layer or active material layer is formed from a composition other than the inorganic solid electrolyte composition of the present invention, commonly used compositions can be cited as materials. Furthermore, in the manufacture of an all-solid-state secondary battery, instead of forming a negative electrode active material layer, ions and electrons of metals belonging to Group 1 or Group 2 of the periodic table accumulated in the negative electrode current collector during initialization or charging (described later) combine and are deposited as metal on the negative electrode current collector, thereby forming a negative electrode active material layer.

[0454] <Formation of each layer (film formation)>

[0455] There are no particular limitations on the coating method for the inorganic solid electrolyte composition, and appropriate methods can be selected. For example, wet coating methods such as spraying, spin coating, dip coating, slot coating, strip coating, and bar coating can be cited.

[0456] At this time, the inorganic solid electrolyte composition can be dried after separate coating (heat treatment) or after multi-layer coating. The drying temperature is not particularly limited as long as it removes the dispersion medium, and is appropriately set according to the boiling point of the dispersion medium. For example, the lower limit of the drying temperature is preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. The upper limit is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. By heating within this temperature range, the dispersion medium can be removed to obtain a solid state (coated drying layer). Furthermore, it avoids excessively high temperatures and damage to the components of the all-solid-state secondary battery, which is therefore preferable. As a result, the all-solid-state secondary battery exhibits excellent overall performance and achieves good coating adaptability (adhesion) and good ion conductivity even without pressure.

[0457] As described above, when the inorganic solid electrolyte composition of the present invention is coated and dried, deviations in the contact state can be suppressed and solid particles can be bonded together, and a coated and dried layer with a flat surface can be formed.

[0458] After coating with an inorganic solid electrolyte composition, the layers are overlapped to form a solid-state secondary battery, or after fabrication of an all-solid-state secondary battery, each layer or the all-solid-state secondary battery is pressurized. Examples of pressurization methods include hydraulic cylinder presses. There are no particular limitations on the pressurization pressure, but a range of 5 to 1500 MPa is generally preferred.

[0459] Furthermore, the coated inorganic solid electrolyte composition can be heated simultaneously with pressurization. There are no particular limitations on the heating temperature, which is generally in the range of 30 to 300°C. Pressing can also be performed at temperatures higher than the glass transition temperature of the inorganic solid electrolyte. Additionally, pressing can be performed at temperatures higher than the glass transition temperature of the dispersant or the polymer constituting the polymer binder. However, the temperature is generally no higher than the melting point of the polymer.

[0460] Pressurization can be performed either with the solvent or dispersion medium pre-dried or with residual solvent or dispersion medium remaining.

[0461] Alternatively, the various compositions can be coated simultaneously, or the coating, drying, and stamping can be performed simultaneously and / or sequentially. They can be laminated by transfer printing after being coated onto their respective substrates.

[0462] There are no particular restrictions on the environment used for coating or pressurization; it can be any environment, such as atmospheric pressure, dry air (dew point below -20°C), or inert gases (e.g., argon, helium, nitrogen).

[0463] The stamping time can be either a short period of time (e.g., within a few hours) to apply high pressure, or a long period of time (more than one day) to apply medium pressure. In the case of solid-state secondary batteries, except for sheets for all-solid-state secondary batteries, medium pressure can be continuously applied using the constraint tools of all-solid-state secondary batteries (such as screw tightening pressure).

[0464] Compared to the pressure-bearing parts such as the surface of the sheet, the stamping pressure can be uniform or varying.

[0465] The stamping pressure can be varied according to the area or film thickness of the pressed part. Furthermore, it is also possible to apply different pressures to the same part in stages.

[0466] The stamped surface can be smooth or rough.

[0467] <Initialization>

[0468] All-solid-state secondary batteries manufactured in the manner described above are preferably initialized after manufacturing or before use. There are no particular limitations on initialization; for example, initial charging and discharging can be performed under increased stamping pressure, followed by releasing the pressure until the normal operating pressure of the all-solid-state secondary battery is reached.

[0469] Applications of all-solid-state rechargeable batteries

[0470] The all-solid-state secondary battery of this invention is applicable to a wide variety of uses. There are no particular limitations on its application; for example, when incorporated into electronic devices, it can be used in laptops, pen-and-paper computers, mobile computers, e-book readers, mobile phones, cordless phones, pagers, handheld terminals, portable fax machines, portable copiers, portable printers, stereo headphones, camcorders, LCD TVs, portable vacuum cleaners, portable CD players, mini disk drives, electric shavers, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, etc. As other civilian products, it can be used in automobiles (electric vehicles), electric vehicles, motors, lighting fixtures, toys, game consoles, load conditioners, clocks, flashlights, cameras, and medical devices (pacemakers, hearing aids, and shoulder massagers, etc.). Furthermore, it can be used in various military and aerospace applications. It can also be combined with solar cells.

[0471] Example

[0472] The present invention will now be described in further detail with reference to embodiments, but the invention is not limited thereto. In the following embodiments, unless otherwise specified, "parts" and "%" of composition refer to mass. In the present invention, "room temperature" refers to 25°C.

[0473] The tensile fracture strain and mass-average molecular weight are values ​​obtained by the methods described above.

[0474] 1. Synthesis of polymer adhesives

[0475] The polymer adhesive shown in the following chemical formula was synthesized as follows.

[0476] [Synthesis Example 1-1: Synthesis of Fluorine Copolymer B-1]

[0477] A fluorinated copolymer B-1 was synthesized, and an adhesive solution B-1 (concentration 10% by mass) composed of this fluorinated copolymer was prepared.

[0478] Specifically, 200 parts by mass of ion-exchanged water, 126 parts by mass of vinylidene fluoride, and 74 parts by mass of hexafluoropropylene were added to an autoclave, along with 1 part by mass of diisopropyl peroxide. The mixture was stirred at 30°C for 24 hours. After polymerization, the precipitate was filtered and dried at 100°C for 10 hours to obtain polymer (adhesive) B-1. The obtained polymer was a random copolymer with a mass-average molecular weight of 70,000 and a tensile breaking strain of 3000%. The obtained polymer B-1 was dissolved in the dispersion medium (butyl butyrate, isobutyl ethyl ether, or heptane) shown in the table to obtain adhesive solution B-1.

[0479] [Synthetic Examples 1-2: Synthesis of Acrylonitrile Homopolymer B-2]

[0480] Acrylonitrile homopolymer B-2 was synthesized, and an adhesive solution B-2 (concentration 10% by mass) composed of this acrylonitrile homopolymer was prepared.

[0481] Specifically, 30.0 g of acrylonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.36 g of polymerization initiator V-601 (trade name, manufactured by FUJIFILM Wako Pure Chemical Corporation) were added to a 100 mL volumetric flask and dissolved in 36 g of butyl butyrate to prepare a monomer solution. 18 g of butyl butyrate was added to a 300 mL three-necked flask, and the monomer solution was added dropwise over 2 hours at 80 °C with stirring. After the addition was complete, the temperature was raised to 90 °C, stirred for 2 hours, and polymer B-2 was synthesized, yielding an adhesive solution B-2 (concentration 10% by mass) composed of polymer B-2. The mass-average molecular weight was 68,000.

[0482] The following shows the synthesized polymers. The numbers listed in the lower right corner of each component indicate the content (mol%).

[0483] Furthermore, the adsorption rate of polymer B-1 for inorganic solid electrolytes was 0% when the dispersion medium was butyl butyrate and 0% when the dispersion medium was isobutyl ethyl ether, while the adsorption rate of polymer B-2 for inorganic solid electrolytes was 18% when the dispersion medium was butyl butyrate.

[0484] In addition, the adsorption rate of the polymer binder for the inorganic solid electrolyte was also measured in the section on [Determination of the Adsorption Rate of the Dispersant for the Inorganic Solid Electrolyte], except that the binder was used instead of the dispersant.

[0485] [Chemical Formula 5]

[0486]

[0487] 2. Synthesis of sulfide-based inorganic solid electrolytes

[0488] [Synthesis Example A]

[0489] The sulfide-based inorganic solid electrolyte was synthesized with reference to non-patent literature, T. Ohtomo, A. Hayashi, M. Tatsumisago, Y. Tsuchida, S. Hama, K. Kawamoto, Journal of Power Sources, 233, (2013), pp231-235 and A. Hayashi, S. Hama, H. Morimoto, M. Tatsumisago, T. Minami, Chem. Lett., (2001), pp872-873.

[0490] Specifically, 2.42 g of lithium sulfide (Li₂S, manufactured by Aldrich, Inc., purity > 99.98%) and 3.90 g of phosphorus pentasulfide (P₂S₅, manufactured by Aldrich, Inc., purity > 99%) were weighed out in a glove box under an argon atmosphere (dew point -70°C) and placed into an agate mortar. The mixture was then mixed for 5 minutes using an agate pestle. The molar ratio of Li₂S to P₂S₅ was set as Li₂S:P₂S₅ = 75:25.

[0491] Next, 66g of 5mm diameter zirconia beads were added to a 45mL zirconia container (manufactured by Fritsch Co., Ltd.), along with the total amount of the aforementioned mixture of lithium sulfide and phosphorus pentasulfide. The container was then completely sealed under argon atmosphere. The container was placed in a planetary ball mill P-7 (trade name, manufactured by Fritsch Co., Ltd.), and mechanically ground at 25°C and 510 rpm for 36 hours, yielding 6.20g of a yellow powder sulfide-based inorganic solid electrolyte (Li-PS glass, hereinafter, sometimes labeled LPS). The Li-PS glass had a particle size of 4μm.

[0492] 3. Synthesis of dispersants

[0493] [Synthetic Example 2-1: Synthesis of Dispersant C-2 (C-2a, C-2b)]

[0494] A monomer solution was prepared by adding 5.4 g of styrene (manufactured by Tokyo Chemical Industry Co., Ltd.), 28.0 g of dodecyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.5 g of maleic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.), and polymerization initiator V-601 (trade name, manufactured by FUJIFILM WakoPure Chemical Corporation) to a 100 mL volumetric flask and dissolving them in 36 g of butyl butyrate. 18 g of butyl butyrate was added to a 300 mL three-necked flask, and the monomer solution was added dropwise over 2 hours at 80 °C with stirring. After the addition was complete, the temperature was raised to 90 °C, and the mixture was stirred for 2 hours to synthesize dispersants C-2 (C-2a, C-2b).

[0495] In addition, the amount of polymerization initiator V-601 added was 3.6 g in the synthesis of dispersant C-2a and 5.0 g in the synthesis of dispersant C-2b.

[0496] [Synthesis Example 2-2: Synthesis of Dispersant C-3]

[0497] In the synthesis example 1-2 of polymer adhesive (synthesis of acrylonitrile homopolymer), dispersant C-3 was synthesized in the same manner as in the synthesis example 1-2, except that the amount of polymerization initiator V-601 was changed to 3.6 g.

[0498] [Synthetic Example 2-3: Synthesis of Dispersant C-11]

[0499] In the synthesis examples 1-2 of polymer adhesives (synthesis of acrylonitrile homopolymer), except that the monomer composition was changed to 10.1 g of acrylonitrile and 19.9 g of styrene, and the amount of polymerization initiator V-601 was changed to 3.6 g, the dispersant C-11 was synthesized in the same manner as in the synthesis examples 1-2.

[0500] [Example 1]

[0501] <Preparation of Inorganic Solid Electrolyte Compositions (Slurries)>

[0502] In a container of a rotation-revolution mixer (ARE-310, manufactured by THINKY CORPORATION), 2.8 g of LPS synthesized in Synthesis Example A, 0.08 g of the binder solution prepared above (solid component mass), 0.03 g of dispersant, and the dispersion medium shown in the table were added to make the content of the dispersion medium in the composition 50% by mass. Then, the container was placed in a rotation-revolution mixer ARE-310 (trade name) manufactured by THINKY CORPORATION. Mixing was carried out at 25°C and 2000 rpm for 5 minutes to prepare inorganic solid electrolyte compositions (slurries) S-1 to S-21.

[0503] The composition comprises LPS 96% by mass, binder 3% by mass, and dispersant 1% by mass, excluding the dispersion medium, in a total content of 100% by mass. Additionally, LLZ (Li7La3Zr2O) is used instead of LPS. 12 Composition S-12 was prepared by using 2.8 g of the product (manufactured by TOYOSHIMA MFG Co,.Ltd.). Composition S-1 was prepared in the same manner except that no dispersant was used, and composition S-15 was prepared in the same manner except that no binder was used. In composition S-15, in a total content of 100% by mass excluding the dispersion medium, LPS was 98.9% by mass and the dispersant was 1.1% by mass.

[0504] <Preparation of the positive electrode composition (slurry)>

[0505] In a container made using a rotation-revolution mixer (ARE-310, manufactured by THINKY CORPORATION), 2.8 g of LPS synthesized in Synthesis Example A, 0.16 g of binder solution (solid content by mass), 0.16 g of dispersant, and the dispersion medium shown in the table were added to make the content of the dispersion medium in the positive electrode composition 50% by mass. The container was then placed in a THINKY CORPORATION ARE-310 rotation-revolution mixer (trade name) and mixed for 2 minutes at 25°C and 2000 rpm. Then, LiNi, as the positive electrode active material, was added to the container. 1 / 3 Co 1 / 3 Mn 1 / 3 13.2 g of O2 (made by Aldrich, CO.LTD.) and 0.32 g of acetylene black (AB) as a conductive additive were placed in a rotation-revolution mixer ARE-310 and mixed at 25°C and 2000 rpm for 2 minutes to prepare positive electrode compositions (slurries) P-1 to P-18.

[0506] The content of each component in the composition, excluding the dispersion medium, is as follows (100% by mass): LPS 17% by mass, NMC 79% by mass, binder 1% by mass, AB 2% by mass, and dispersant 1% by mass. Additionally, LLZ (Li7La3Zr2O) is used instead of LPS. 12 Composition P-10 was prepared by using 2.8 g of the product (manufactured by TOYOSHIMA MFG Co,.Ltd.). Composition P-1 was prepared in the same manner except that no dispersant was used, and composition P-13 was prepared in the same manner except that no binder was used. In composition P-13, in a total content of 100% by mass of components other than the dispersion medium, LPS was 17% by mass, NMC was 80% by mass, AB was 2% by mass, and the dispersant was 1% by mass.

[0507] <Preparation of the negative electrode composition (slurry)>

[0508] In a container of a rotation-revolution mixer (ARE-310, manufactured by THINKY CORPORATION), 2.8 g of LPS synthesized in Synthesis Example A, 0.08 g of binder solution (solid content mass), 0.08 g of dispersant, and the dispersion medium shown in the table were added to make the content of the dispersion medium in the composition 50% by mass. Then, the container was placed in a THINKY CORPORATION rotation-revolution mixer ARE-310 (trade name) and mixed at 25°C and 2000 rpm for 2 minutes. Then, 3.53 g of silicon (Si, manufactured by Aldrich) as the negative electrode active material and 0.27 g of VGCF (trade name, carbon nanotubes, manufactured by SHOWA DENKO KK) as the conductive additive were added and placed in the same rotation-revolution mixer ARE-310 (trade name) and mixed at 25°C and 2000 rpm for 2 minutes to prepare negative electrode compositions (slurries) N-1 to N-8.

[0509] The components in the composition, excluding the dispersion medium, are in the following proportions out of a total of 100% by mass: LPS 41% by mass, Si 52% by mass, binder 1% by mass, VGCF 4% by mass, and dispersant 1% by mass. Additionally, compositions N-5 to N-8 were prepared by using 3.53g of graphite (Gr, Hohsen Corp.) instead of silicon.

[0510] For each composition prepared, the types of active substances, inorganic solid electrolytes, binders, dispersants, and dispersion media used are shown in Table 1. Furthermore, Table 1 summarizes the SP values ​​of the dispersants and dispersion media calculated by the above methods, their differences, the molecular weight of the dispersants, and the adsorption rates of the inorganic solid electrolytes determined by the methods described below.

[0511] In addition, No. S-4, S-7 to S-15, S-18, S-19, S-21, P-6 to P-13, P-15 to P-18, N-3, N-4, N-7 and N-8 are inorganic solid electrolyte compositions of the present invention, and No. S-1 to S-3, S-5, S-6, S-16, S-17, S-20, P-1 to P-5, P-14, N-1, N-2, N-5 and N-6 are inorganic solid electrolyte compositions for comparison.

[0512] [Determination of the adsorption rate of dispersants for inorganic solid electrolytes]

[0513] The adsorption rate was determined using the inorganic solid electrolytes, dispersants, and dispersion media used to prepare the inorganic solid electrolyte compositions shown in Table 1.

[0514] Specifically, a 1% (w / w) dispersant solution was prepared by dissolving the aforementioned dispersant in a dispersion medium. With a dispersant-to-inorganic solid electrolyte mass ratio of 42:1, the dispersant solution and inorganic solid electrolyte were placed in a 15 mL vial and stirred for 1 hour at 80 rpm using a mixing rotor at room temperature (25°C). The mixture was then allowed to stand. The supernatant obtained from solid-liquid separation was filtered through a 1 μm filter. The filtrate was completely dried, and the mass of the dispersant remaining in the filtrate (the mass of the dispersant not adsorbed onto the inorganic solid electrolyte) W was measured. A The mass W A and the mass W of the dispersant contained in the dispersant solution used for measurement B The adsorption rate of the dispersant on the inorganic solid electrolyte can be calculated using the following formula.

[0515] The adsorption rate of the dispersant is set as the average value of the adsorption rates obtained by performing the above determination twice.

[0516] Adsorption rate (%) = [(W) B -W A ) / W B ]×100

[0517] In addition, the same value was obtained by measuring the adsorption rate using inorganic solid electrolyte and dispersant taken from the solid electrolyte layer formed by film, and the dispersion medium used to prepare the composition containing inorganic solid electrolyte.

[0518]

[0519]

[0520]

[0521] <Abbreviation for table>

[0522] LPS: LPS synthesized in Synthesis Example A

[0523] LLZ: Li7La3Zr2O 12

[0524] NMC: LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2

[0525] Si: Silicon

[0526] Gr: Graphite

[0527] Adhesives B-1 and B-2: Polymer adhesives B-1 and B-2 synthesized in the above synthesis examples

[0528] Dispersants C-1 to C-13 and C-21: The following dispersants C-1 to C-13 and C-21. C-2 (C-2a, C-2b), C-3, and C-11 refer to the dispersants synthesized in the above-described synthesis examples. Furthermore, the solubility of these dispersants in the dispersion medium constituting the composition was determined by measuring the transmittance as described above, and the results were all 10% by mass or more.

[0529] [Chemical Formula 6]

[0530]

[0531] The units for "SP value" and "SP value difference Δ" in the table are MPa. 1 / 2 The unit for "Adsorption rate of inorganic solid electrolytes" is %. "SP value difference Δ" is expressed as an absolute value, representing the difference between the SP value of the dispersion medium and the SP value of the dispersant.

[0532] Regarding the boiling points of the dispersion media, butyl butyrate is 164℃, isobutyl ethyl ether is 133℃, and heptane is 98℃.

[0533] <Fabrication of Solid Electrolyte Sheets for All-Solid-State Secondary Batteries>

[0534] The inorganic solid electrolyte compositions S-1 to S-21 obtained above were prepared. After 1 hour, they were coated onto 20 μm thick aluminum foil using a baking applicator (trade name: SA-201, manufactured by TESTER SANGYO CO,.LTD.). The coatings were then heated at 110°C for 2 hours and dried (to remove the dispersion medium). Next, the dried inorganic solid electrolyte compositions were pressurized for 10 seconds at 25°C and 10 MPa using a hot press to produce solid electrolyte sheets S-1 to S-21 for all-solid-state secondary batteries. The solid electrolyte layer thickness was 50 μm.

[0535] <Fabrication of Positive Electrode Sheets for All-Solid-State Secondary Batteries>

[0536] The above-obtained positive electrode compositions P-1 to P-18 were prepared. After 1 hour, they were coated onto 20 μm thick aluminum foil using a baking applicator (trade name: SA-201). The positive electrode compositions were then dried at 110°C for 1 hour (to remove the dispersion medium). Then, the dried positive electrode compositions were pressurized at 25°C (10 MPa, 1 minute) using a hot press to produce positive electrode sheets P-1 to P-18 for all-solid-state secondary batteries, each with a 100 μm thick positive electrode active material layer.

[0537] <Fabrication of negative electrode sheets for all-solid-state secondary batteries>

[0538] The aforementioned negative electrode compositions N-1 to N-8 were prepared. After 1 hour, they were coated onto a 20 μm thick copper foil using a baking applicator (trade name: SA-201). The coating was heated at 110°C for 1 hour, and then dried at 110°C for 2 hours using a vacuum dryer AVO-200NS (trade name, manufactured by AS ONE Corporation) to remove the dispersion medium. The dried negative electrode compositions were then pressurized at 25°C (10 MPa, 1 minute) using a hot press to fabricate all-solid-state secondary battery negative electrode sheets N-1 to N-8, each with a 70 μm thick negative electrode active material layer.

[0539] The various compositions and sheets manufactured were evaluated as follows, and the results are shown in Table 2.

[0540] <Evaluation 1: Dispersion Characteristics (Dispersion)>

[0541] In the following dispersibility test, samples were taken from the compositions coated on the substrate in the above-described sheet manufacturing methods.

[0542] Each sampled composition (slurry) was suspended in the tank of a particle size analyzer (grinding tester) type 232 / III (trade name, manufactured by AS ONE Corporation), and the value read from the position of the line appearing after scraping with a scraper was taken as the agglomeration size X. On the other hand, the agglomeration size X0 of the composition with the viscosity adjusted to 300 cP was measured in the same way as the agglomeration size X. The agglomeration size ratio [X / X0] was calculated using the obtained agglomeration sizes X and X0.

[0543] Furthermore, the composition with a viscosity of 300 cP was prepared by maintaining the proportions of components other than the dispersion medium relative to the sampled compositions (slurries) while adjusting the amount of dispersion medium. The viscosity, as described above, was obtained using an E-type viscometer.

[0544] The aggregation size ratio [X / X0] is included in any of the following evaluation criteria, which evaluate the ease with which solid particles aggregate as a measure of the dispersibility of the composition.

[0545] In this experiment, the smaller the agglomeration size ratio [X / X0], the more difficult it is for solid particles to agglomerate or precipitate, indicating excellent dispersibility. Evaluation standard "F" and above are considered qualified.

[0546] -Evaluation Criteria-

[0547] A: X / X0 < 1.1

[0548] B: 1.1 ≤ X / X0 < 1.2

[0549] C: 1.2 ≤ X / X0 < 1.3

[0550] D: 1.3 ≤ X / X0 < 1.4

[0551] E: 1.4 ≤ X / X0 < 1.5

[0552] F: 1.5 ≤ X / X0 < 1.6

[0553] G: 1.6 ≤ X / X0

[0554] <Evaluation 2: Dispersion Characteristics (Stability)>

[0555] In the following dispersion stability test, samples were taken from the compositions coated on the substrate in the above-mentioned sheet manufacturing methods.

[0556] Each sampled composition (slurry) was placed into a glass test tube with a diameter of 10 mm and a height of 4 cm until the height reached 4 cm, and allowed to stand at 25°C for 24 hours. The reduction rate of solids in the top 30% (height) of the composition before and after standing was calculated using the following formula. Based on whether this reduction rate of solids was included in any of the following evaluation criteria, the ease with which solid particles precipitated over time was evaluated as the dispersion stability (storage stability) of the composition. In this test, the smaller the reduction rate of solids, the better the dispersion stability; an evaluation criterion of "F" or higher is considered acceptable.

[0557] Solid content reduction rate (%) = [(Solid content concentration of the top 30% before settling - Solid content concentration of the top 30% after settling) / Solid content concentration of the top 30% before settling] × 100

[0558] -Evaluation Criteria-

[0559] A: Solid content reduction rate <1%

[0560] B: 1% ≤ reduction rate of solid content < 3%

[0561] C: 3% ≤ Solid content reduction rate < 5%

[0562] D: 5% ≤ Solid content reduction rate < 7%

[0563] E: 7% ≤ Solid content reduction rate < 9%

[0564] F: 9% ≤ Solid content reduction rate < 11%

[0565] G: 11% ≤ reduction rate of solid content

[0566] <Evaluation 3: Coating suitability (surface properties)>

[0567] To assess the coating suitability of each composition, the maximum height roughness Rz of the solid electrolyte layer surface or active material layer surface of each obtained sheet was measured and evaluated.

[0568] Specifically, the maximum height roughness Rz of the solid electrolyte layer surface or active material layer surface of each sheet was measured under the following measuring apparatus and conditions according to Japanese Industrial Standard (JIS) B 0601:2013.

[0569] The maximum height roughness Rz is included in any of the following evaluation criteria, and is used to evaluate the ease of forming a constituent layer with a flat surface and good surface properties as part of the coating suitability of the composition (surface properties). In this test, the smaller the above-mentioned maximum height roughness Rz, the better the coating suitability (surface properties), and the evaluation criterion "F" and above is considered acceptable.

[0570] -Measuring Apparatus and Conditions-

[0571] Measurement Apparatus: Three-dimensional micro-shape measuring instrument (Model ET-4000A, manufactured by Kosaka Laboratory Ltd.)

[0572] Analysis equipment: Three-dimensional surface roughness analysis system (model TDA-31)

[0573] Stylus: Tip radius 0.5μm, made of diamond

[0574] Needle pressure: 1μN

[0575] Measurement length: 5.0 mm

[0576] Measurement speed: 0.02 mm / s

[0577] Measurement interval: 0.62 μm

[0578] Cutoff value: None

[0579] Filtering method: Gaussian space type

[0580] Leveling: (with quadratic curve)

[0581] -Evaluation Criteria-

[0582] A: Rz < 1.0 μm

[0583] B: 1.0μm≤Rz<2.0μm

[0584] C: 2.0μm≤Rz<4.0μm

[0585] D: 4.0μm ≤ Rz < 6.0μm

[0586] E: 6.0μm≤Rz<8.0μm

[0587] F: 8.0μm≤Rz<10μm

[0588] G: 10μm≤Rz

[0589] <Evaluation 4: Coating Suitability (Adhesion)>

[0590] As for the coating suitability of each composition, the adhesion of solid particles in the solid electrolyte layer or active material layer of each obtained sheet and the adhesion between the active material layer and the current collector were evaluated.

[0591] Each sheet was cut into a rectangle 3cm wide x 14cm long. Using a cylindrical mandrel testing machine (product code 056, mandrel diameter 10mm, manufactured by Allgood), one end of the cut sheet was fixed in the machine along its length, and the central portion of the sheet was positioned to abut against the cylindrical mandrel. While stretching the other portion of the sheet along its length with a force of 5N, it was bent 180° along the circumference of the mandrel (with the mandrel as the axis). Furthermore, the solid electrolyte layer or active material layer of the sheet was placed on the side opposite to the mandrel (the substrate or current collector was placed on the mandrel side), and the width direction was set parallel to the axis of the mandrel. The test was conducted by gradually reducing the diameter of the mandrel from 32mm.

[0592] The evaluation is conducted under the following conditions: in the state of being wound on a mandrel and in the state of being unwound and restored to a sheet shape, the generation of defects (cracks, fissures, gaps, etc.) caused by the bonding collapse of solid particles on the solid electrolyte layer or active material layer is measured. For the active material layer, the minimum diameter at which the peeling between the active material layer and the current collector cannot be confirmed is further measured. This minimum diameter corresponds to any of the following evaluation criteria.

[0593] In this test, the smaller the minimum diameter, the stronger the adhesion of the solid particles constituting the solid electrolyte layer or active material layer, and the stronger the adhesion between the active material layer and the current collector. Evaluation standard "F" and above is considered qualified.

[0594] -Evaluation Criteria-

[0595] A: Minimum diameter < 5mm

[0596] B: 5mm ≤ minimum diameter < 6mm

[0597] C: 6mm ≤ minimum diameter < 8mm

[0598] D: 8mm ≤ minimum diameter < 10mm

[0599] E: 10mm ≤ minimum diameter < 14mm

[0600] F: 14mm ≤ minimum diameter < 25mm

[0601] G: 25mm ≤ minimum diameter

[0602] <Evaluation 5: Upper Limit Concentration of Pulping>

[0603] In the preparation of the above compositions (slurries), compositions with a solids concentration of 76% by mass were prepared by varying the amount of dispersion medium. The prepared compositions with a solids concentration of 76% by mass were placed in a container (a cylindrical container for a 5.0cm diameter, 7.0cm height rotary mixer (trade name: ARE-310, manufactured by THINKYCORPORATION) placed on a table until the volume reached approximately 1.0cm. The container was then tilted at a 60-degree angle to check for flowability to the extent that it would sag under its own weight. If the composition did not sag under its own weight and lacked flowability, butyl butyrate was added as the dispersion medium to reduce the solids concentration of the composition by 1% by mass. The mixture was then dispersed at 2000 rpm for 1 minute in the rotary mixer, and flowability was checked again in the same manner as with the composition with a solids concentration of 76% by mass. This operation was repeated by reducing the solids concentration by 1% by mass for each composition, and the maximum solids concentration exhibiting flowability was taken as the upper limit concentration for slurry preparation. The maximum concentration of a thick slurry that could be prepared was evaluated. When the concentration of solid components is increased to a level exceeding the upper limit of the slurry concentration, it becomes difficult to use the composition in the coating process. Therefore, the upper limit of the slurry concentration becomes an indicator of the upper limit of the solid component concentration of the composition that can be used in the coating process, and a higher level is preferred.

[0604] In the table below, the upper limit concentration of slurry is expressed in mass%.

[0605] [Table 2-1]

[0606]

[0607] [Table 2-2]

[0608]

[0609] [Table 2-3]

[0610]

[0611] <Manufacturing of All-Solid-State Secondary Batteries>

[0612] An all-solid-state secondary battery was manufactured by using the positive electrode sheet, the solid electrolyte sheet, and the negative electrode sheet for an all-solid-state secondary battery in the combination of the constituent layers shown in Table 3.

[0613] The positive electrode sheets P-1, P-4, or P-8 for the all-solid-state secondary battery are punched into 10mm diameter discs and placed in a PET cylinder with an inner diameter of 10mm. Inside the cylinder, solid electrolyte sheets S-1, S-5, or S-10 for the all-solid-state secondary battery are punched into 10mm diameter discs on the positive electrode active material layer side and placed inside the cylinder. 10mm SUS rods are inserted through openings at both ends of the cylinder. A pressure of 350MPa is applied to the current collector side of the positive electrode sheet and the aluminum foil side of the solid electrolyte sheet through the SUS rods. The SUS rods are temporarily removed from the solid electrolyte sheet side, and the aluminum foil of the solid electrolyte sheet is gently peeled off. Then, negative electrode sheets N-1, N-2, or N-4 are punched into 10mm diameter discs and inserted into the solid electrolyte layer of the solid electrolyte sheet inside the cylinder. The removed SUS rod was reinserted into the cylinder and fixed under a pressure of 50 MPa. This yielded all-solid-state secondary batteries No. C-1 to C-9 with a structure consisting of aluminum foil (20 μm thick), a positive electrode active material layer (90 μm thick), a solid electrolyte layer (45 μm thick), and a negative electrode active material layer (65 μm thick).

[0614] In addition, No. C-1 to C-4 and C-6 to C-8 are all-solid-state secondary batteries of the present invention, and No. C-5 and C-9 are all-solid-state secondary batteries used for comparison.

[0615] <Evaluation 5: Cyclic Characteristics>

[0616] For each of the manufactured all-solid-state secondary batteries, the discharge capacity retention was measured using the TOSCAT-3000 charge-discharge evaluation device (trade name, manufactured by TOYO SYSTEM Co., Ltd.).

[0617] Specifically, each all-solid-state secondary battery was charged at 25°C until the current density reached 0.1 mA / cm². 2 And continue discharging until the battery voltage reaches 3.6V. Then, discharge until the current density reaches 0.1mA / cm². 2The battery voltage was maintained until it reached 2.5V. One charge and one discharge cycle was considered one initial charge-discharge cycle, and this was repeated for three cycles under the same conditions to initialize the battery. Then, under the same conditions as the initial charge-discharge cycle, the charge-discharge cycle was repeated 1000 times. The discharge capacity of the first and 1000th cycles was measured using a TOSCAT-3000 (trade name) charge-discharge evaluation device. The discharge capacity retention rate was calculated using the following formula, and this rate was applied to the following evaluation criteria to evaluate the cycle characteristics of the all-solid-state secondary battery. In this test, a higher evaluation criterion indicates better battery performance (cycle characteristics), and the battery can maintain its initial performance even after repeated charge-discharge cycles (even with long-term use). In this test, an evaluation criterion of "F" or higher is considered acceptable.

[0618] Furthermore, the initial discharge capacity of the all-solid-state secondary batteries of the present invention all show values ​​sufficient for functioning as all-solid-state secondary batteries.

[0619] Discharge capacity retention (%) = (Discharge capacity in the 1000th cycle / Discharge capacity in the 1st cycle) × 100

[0620] -Evaluation Criteria-

[0621] A: 90% ≤ Discharge Capacity Maintenance Rate

[0622] B: 85% ≤ Discharge Capacity Retention < 90%

[0623] C: 80% ≤ Discharge capacity retention < 85%

[0624] D: 75% ≤ Discharge Capacity Retention < 80%

[0625] E: 70% ≤ Discharge capacity retention < 75%

[0626] F: 60% ≤ Discharge capacity retention < 70%

[0627] G: Discharge capacity retention rate < 60%

[0628] [Table 3]

[0629]

[0630] The following information can be obtained from the results shown in Tables 2 and 3.

[0631] The comparative inorganic solid electrolyte compositions No. S-1 and P-1 do not contain the dispersant specified in this invention; the comparative inorganic solid electrolyte compositions No. S-5, S-6, P-4, and P-5 do not contain dispersants with SP values ​​within the range specified in this invention; and the comparative inorganic solid electrolyte compositions No. S-3, P-3, N-2, and N-6 do not contain dispersants with molecular weights within the range specified in this invention. These compositions exhibit poor dispersion characteristics and coating suitability. Furthermore, the comparative inorganic solid electrolyte compositions No. S-2, S-16, P-2, P-14, N-1, and N-5 do not contain dispersants with adsorption rates within the range specified in this invention. These compositions exhibit poor dispersion characteristics (stability) and coating suitability (adhesion). Furthermore, the comparative inorganic solid electrolyte composition No. S-17 does not contain dispersants with SP values ​​and adsorption rates meeting the range specified in this invention, and the comparative inorganic solid electrolyte composition No. S-20 does not contain a dispersion medium exhibiting a boiling point within the range specified in this invention. These compositions have poor dispersion characteristics and coating suitability.

[0632] Furthermore, the comparative all-solid-state secondary batteries No. C-5 and C-9, which used these comparative inorganic solid electrolyte compositions to form the layers, did not exhibit sufficient cycling characteristics.

[0633] In contrast, the inorganic solid electrolyte compositions No. S-4, S-7 to S-15, S-18, S-19, S-21, P-6 to P-13, P-15 to P-18, N-3, N-4, N-7, and N-8 of the present invention contain a dispersant that satisfies any one of the ranges of SP value, molecular weight, and adsorption rate specified in the present invention, and a dispersion medium exhibiting a boiling point within the range specified in the present invention. These compositions possess both high levels of dispersion characteristics (dispersibility and stability) and coating suitability (surfaceability and adhesion). By using these inorganic solid electrolyte compositions to form any layer of the constituent layer of an all-solid-state secondary battery, as shown in No. C-1 to C-4 and C-6 to C-8, it is evident that all-solid-state secondary batteries exhibiting excellent cycle characteristics can be manufactured.

[0634] Furthermore, in the negative electrode composition, in addition to what has been shown above, when the dispersant used in the above-mentioned inorganic solid electrolyte composition or positive electrode composition is used, the same effect as that in the inorganic solid electrolyte composition or positive electrode composition can be obtained.

[0635] The invention has been described together with its embodiments, but unless otherwise specified, the invention is not limited in any detail of the description and should be interpreted broadly without departing from the spirit and scope of the invention as shown in the appended claims.

[0636] This application claims priority based on Japanese Patent Application 2020-166555, filed on September 30, 2020, the contents of which are incorporated herein by reference and are part of the description herein.

[0637] Symbol Explanation

[0638] 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.

Claims

1. A composition containing an inorganic solid electrolyte for use in an all-solid-state secondary battery, the composition comprising: an inorganic solid electrolyte having conductive ions of metals belonging to Group 1 or Group 2 of the periodic table, a dispersant, and a dispersion medium. The inorganic solid electrolyte includes at least one of sulfide-based inorganic solid electrolytes and oxide-based inorganic solid electrolytes. The dispersant comprises: It meets the requirements of (1) to (3) below and is selected from at least one of the following compounds and polymers. The compound is composed of R X -A 1 and R Y -A 2 The polymer is a polymer comprising any of the compounds represented in the group consisting of functional groups selected from the following functional group (a1). The dispersion medium comprises at least one compound selected from ester compounds, ketone compounds, ether compounds, aromatic compounds, and aliphatic compounds, having a boiling point above 120°C. (1) The SP value of the dispersant is 17.0~22.0MPa 1 / 2 , (2) The molecular weight of the dispersant is below 10,000. (3) The adsorption rate of the dispersant on the inorganic solid electrolyte in the dispersion medium is more than 2%. The above R X Represents an alkyl group, and the above R Y Indicating no substituted aryl group, the above A 1 and A 2 This indicates a functional group selected from the following functional group (a1). <Functional groups (a1)> Hydroxyl, amino, carboxyl, sulfonyl, phosphate, phosphonic acid, amide, aryl.

2. The inorganic solid electrolyte composition according to claim 1, wherein, The adsorption rate specified in (3) is 40% or higher.

3. The inorganic solid electrolyte composition according to claim 1 or 2, wherein, The difference between the SP value of the dispersion medium and the SP value of the dispersant is 3.0 MPa. 1 / 2 the following.

4. The inorganic solid electrolyte composition according to claim 1 or 2, wherein, The polymer is a chain polymer.

5. The inorganic solid electrolyte composition according to claim 1 or 2, wherein, The content of the aforementioned constituent components in the polymer is 5 to 70 mol%.

6. The inorganic solid electrolyte composition according to claim 1 or 2, wherein it contains a polymer binder.

7. The inorganic solid electrolyte composition according to claim 1 or 2, wherein it contains an active substance.

8. The inorganic solid electrolyte composition according to claim 1 or 2, wherein it contains a conductive additive.

9. The inorganic solid electrolyte composition according to claim 1 or 2, wherein, The inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.

10. A sheet for an all-solid-state secondary battery, having a layer formed from the inorganic solid electrolyte composition according to any one of claims 1 to 9.

11. An all-solid-state secondary battery, comprising sequentially a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, wherein, At least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer has a layer formed by the inorganic solid electrolyte composition according to any one of claims 1 to 9.

12. A method for manufacturing a sheet for an all-solid-state secondary battery, comprising forming a layer containing an inorganic solid electrolyte composition as described in any one of claims 1 to 9.

13. A method for manufacturing an all-solid-state secondary battery, comprising the step of assembling an all-solid-state secondary battery sheet obtained by the manufacturing method of claim 12 onto an all-solid-state secondary battery.

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