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

Abstract

Provided are: an inorganic solid electrolyte-containing composition that contains an inorganic solid electrolyte, a polymer binder, and a dispersion medium, wherein the polymer binder contains a polymer that contains 80 mass% or more of a constitutional unit (D) satisfying the relationships represented by specific formulae (1) to (3) and has at least one specific polar functional group; a sheet for an all-solid-state secondary battery; an all-solid-state secondary battery; and methods for manufacturing the sheet for an all-solid-state secondary battery and an all-solid-state secondary battery.

Description

Composition containing an inorganic solid electrolyte, a sheet for an all-solid-state secondary battery, and an all-solid-state secondary battery, as well as a method for manufacturing the sheet for an all-solid-state secondary battery and an all-solid-state secondary battery.

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

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

[0003] In such all-solid-state secondary batteries, inorganic solid electrolytes, active materials, conductive additives, etc., are used as materials to form the constituent layers (solid electrolyte layer, negative electrode active material layer, positive electrode active material layer, etc.). In recent years, inorganic solid electrolytes, particularly oxide-based inorganic solid electrolytes and sulfide-based inorganic solid electrolytes, have been expected to be electrolyte materials with high ionic conductivity approaching that of organic electrolytes. Constituent layers using inorganic solid electrolytes are usually formed using a material (constituent layer forming material) containing the inorganic solid electrolyte and a binder, taking into consideration the improvement of productivity, etc. For example, Patent Document 1 describes an inorganic solid electrolyte-containing composition containing an inorganic solid electrolyte having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a polymer binder, and a dispersion medium, wherein the polymer binder has a surface energy of 20 mN / m or less and an SP value of 14 to 21.5 MPa. １／２ The description includes "an inorganic solid electrolyte-containing composition that contains a polymer and dissolves in the dispersion medium."

[0004] International Publication No. 2022 / 059567

[0005] Because the constituent layers of an all-solid-state secondary battery are formed from solid particles (inorganic solid electrolyte, active material, conductive additive, etc.), the interfacial contact state between the solid particles, and furthermore, the interfacial contact state between the solid particles and the current collector, is constrained. As a result, interfacial resistance tends to increase, and it is not possible to firmly adhere the solid particles to each other. This increase in interfacial resistance not only increases the battery resistance (decrease in ionic conductivity) of the all-solid-state secondary battery, but also causes a decrease in cycle performance. Moreover, the adhesion force between the solid particles is insufficient, leading to a further decrease in cycle performance. The increase in resistance at the interface and in the battery, which is a factor in the decrease in battery performance, is due not only to the interfacial contact state of the solid particles, but also to the non-uniform distribution (arrangement) of the solid particles within the constituent layers, and furthermore, to the surface flatness of the constituent layers. Therefore, when forming a constituent layer with a constituent layer forming material, the constituent layer forming material is required to have the property of stably maintaining the excellent dispersibility (initial dispersibility) of solid particles immediately after preparation (dispersion stability), and the property of having an appropriate viscosity and high fluidity to form a good coating film (handling properties). Moreover, in recent years, research and development on the high performance and practical application of electric vehicles has been progressing rapidly, and the performance required of all-solid-state secondary batteries has also increased. In order to realize high-performance all-solid-state secondary batteries, the property of maintaining battery capacity even when repeatedly charged at a higher potential than usual (for example, 4.4 to 4.5 V) (also referred to as "high-potential cycle characteristics" in this invention) is also required. However, in Patent Document 1, regarding inorganic solid electrolyte-containing compositions, from the above viewpoint, there has been no study in particular on the relationship between high-potential cycle characteristics and the properties of the constituent components of the polymer that forms the polymer binder, for inorganic solid electrolytes and polymer binders used in combination with dispersion media.

[0006] The present invention aims to provide an inorganic solid electrolyte-containing composition that exhibits excellent dispersion stability and handling properties, and which, when used as a material for forming the constituent layers of an all-solid-state secondary battery, enables the realization of an all-solid-state secondary battery with low resistance and excellent high-potential cycle characteristics. Furthermore, the present invention aims to provide an all-solid-state secondary battery sheet and an all-solid-state secondary battery using this inorganic solid electrolyte-containing composition, as well as a method for manufacturing the all-solid-state secondary battery sheet and all-solid-state secondary battery.

[0007] The inventors of the present invention have conducted various studies on polymers that form polymer binders used in combination with inorganic solid electrolytes and dispersion media in inorganic solid electrolyte-containing compositions. As a result, they have found that by introducing specific polar functional groups into polymers, setting the energy level (eV) of the highest occupied orbital defined by formula (1) and the maximum value of the positive charge on the carbon atom defined by formula (2) within a specific range, and satisfying the specific relationship expressed by formula (3) between the energy level and the maximum value of the positive charge, excellent dispersion stability and handling properties can be achieved. Furthermore, they have found that by using an inorganic solid electrolyte-containing composition containing this polymer binder in combination with an inorganic solid electrolyte, etc., as a constituent layer forming material, it is possible to realize an all-solid-state secondary battery sheet with a low-resistance constituent layer in which solid particles are firmly adhered (bound), and furthermore, an all-solid-state secondary battery with low resistance and excellent high-potential cycle characteristics. The present invention was completed after further studies based on these findings.

[0008] In other words, the above problems were solved by the following means: [1] An inorganic solid electrolyte-containing composition comprising an inorganic solid electrolyte (A) having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a polymer binder (B), and a dispersion medium (C), wherein the polymer forming the polymer binder (B) contains 80% by mass or more of constituent units (D) that satisfy all of the following relationships represented by formulas (1) to (3), and has at least one polar functional group from the following functional group group (a): Formula (1): -8.3 ≤ E ≤ -6.3 Formula (2): 0.2 ≤ σ ≤ 1.2 Formula (3): σ ≤ 1.0 × E + 8.8 In the above formulas, E represents the energy level (eV) of the highest occupied orbital in the constituent unit, and σ represents the maximum value of the positive charge on the carbon atom calculated by Merz-Kollman electrostatic potential fitting in the constituent unit. <Functional group group (a)> Sulfonic acid group, phosphoric acid group, phosphonic acid group, hydroxyl group, carboxyl group, dicarboxylic acid group, thiol group, ether group, ester group, amide group, urethane group, urea group, imide group and salts thereof [2] The inorganic solid electrolyte-containing composition according to [1], wherein formula (3) is formula (3A): σ ≤ 1.0 × E + 8.5. [3] The inorganic solid electrolyte-containing composition according to [1] or [2], wherein formula (3) is the following formula (3B): σ ≤ 1.0 × E + 8.2. [4] The inorganic solid electrolyte-containing composition according to any one of [1] to [3], wherein formula (2) is the following formula (2A): 0.4 ≤ σ ≤ 1.2. [5] The inorganic solid electrolyte-containing composition according to any one of [1] to [4], wherein the polymer binder (B) is dissolved in the dispersion medium (C). [6] The inorganic solid electrolyte-containing composition according to any one of [1] to [5], wherein the constituent unit (D) has at least one polar functional group from the functional group group (a). [7] The inorganic solid electrolyte-containing composition according to any one of [1] to [6], wherein the constituent unit (A) has at least one polar functional group from the functional group group (a) and does not satisfy at least one of the relationships represented by the above formulas (1) to (3). [8] The inorganic solid electrolyte-containing composition according to any one of [1] to [7], wherein the constituent unit (D) comprises a constituent unit derived from a (meth)acrylamide compound or a constituent unit derived from a maleimide compound.[9] An inorganic solid electrolyte-containing composition according to any one of [1] to [8], wherein the acid value of the polymer is 0.20 mmol / g or less.

[10] An inorganic solid electrolyte-containing composition according to any one of [1] to [9], wherein the content of constituent unit (D) is 95% by mass or more.

[11] An inorganic solid electrolyte-containing composition according to any one of [1] to

[10] , containing an active material.

[12] An inorganic solid electrolyte-containing composition according to any one of [1] to

[11] , wherein the inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.

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

[12] .

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

[12] .

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

[12] above.

[16] A method for producing an all-solid-state secondary battery, comprising producing an all-solid-state secondary battery via the method described in

[15] above.

[0009] The present invention provides an inorganic solid electrolyte-containing composition exhibiting excellent dispersion stability and handling properties, which, when used as a constituent layer forming material for an all-solid-state secondary battery, enables the realization of an all-solid-state secondary battery with low resistance and excellent high-potential cycle characteristics. Furthermore, the present invention provides an all-solid-state secondary battery sheet and an all-solid-state secondary battery using this inorganic solid electrolyte-containing composition, as well as a method for manufacturing the all-solid-state secondary battery sheet and all-solid-state secondary battery. The above and other features and advantages of the present invention will become clearer from the following description with reference to the accompanying drawings as appropriate.

[0010] Figure 1 is a schematic longitudinal cross-sectional view showing an all-solid-state secondary battery according to a preferred embodiment of the present invention. Figure 2 is a schematic longitudinal cross-sectional view showing a coin-type all-solid-state secondary battery fabricated in the example. Figure 3 is a Cartesian coordinate system showing the energy level (eV) of the highest occupied orbital and the maximum value of the positive charge on the carbon atom for each constituent unit used in the example and comparative example.

[0011] In the present invention, when describing the content, physical properties, etc., of components by indicating numerical ranges, if the upper and lower limits of the numerical range are described separately, either upper or lower limit can be appropriately combined to form a specific numerical range. On the other hand, when multiple numerical ranges represented by "~" are set and described, the upper and lower limits that form the numerical range are not limited to the specific combination of upper and lower limits written before and after "~" as a specific numerical range, but can be a numerical range formed by appropriately combining the upper and lower limits of each numerical range. In the present invention, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits.

[0012] In this invention, the designation of a compound (for example, when referred to as a compound) includes not only the compound itself, but also its salts and ions. It also includes derivatives in which a part of the compound has been altered, such as by introducing substituents, to the extent that it does not impair the effects of this invention. In this invention, substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) that are not specified as substituted or unsubstituted mean that the group may have appropriate substituents. Therefore, in this invention, even when simply referred to as a YYY group, this YYY group includes not only the unsubstituted form but also the form with substituents. This is also true for compounds that are not specified as substituted or unsubstituted. A preferred substituent is, for example, substituent Z, which will be described later. In this invention, when there are multiple substituents, etc. indicated by a specific symbol, or when multiple substituents, etc. are specified simultaneously, it means that each substituent, etc. may be the same as or different from the others. Also, even if not specifically stated, when multiple substituents, etc. are adjacent, they may be linked to each other or fused to form a ring. In this invention, (meth)acrylic means either or both of acrylic and methacrylic. The same applies to (meth)acrylates.

[0013] In this invention, a polymer binder (sometimes simply referred to as "binder") means a binder composed of a polymer, and includes the polymer itself and binders composed (formed) containing a polymer. In this invention, "polymer" means a polymer, but is synonymous with so-called high-molecular-weight compounds. In this invention, the main chain of a polymer (including the polymerization chain) refers to a linear molecular chain in which all other molecular chains constituting the polymer can be considered as branched chains or pendant groups relative to the main chain. Depending on the weight-average molecular weight of the branched chains considered as branched chains or pendant groups, typically the longest chain among the molecular chains constituting the polymer becomes the main chain. However, the end groups of the polymer ends are not included in the main chain. In contrast, the side chains of a polymer refer to branched chains other than the main chain, and include short chains and long chains (graft chains). The end groups of a polymer are not particularly limited and can take on appropriate groups depending on the polymerization method, etc. Examples of end groups include hydrogen atoms, alkyl groups, aryl groups, hydroxyl groups, and residues such as polymerization initiators.

[0014] [Inorganic Solid Electrolyte-Containing Composition] The inorganic solid electrolyte-containing composition of the present invention contains an inorganic solid electrolyte (A) having the conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a polymer binder (B), and a dispersion medium (C). This polymer binder is formed by containing a polymer having a specific content of a constituent unit (D) described later, and a polar functional group described later. The inorganic solid electrolyte-containing composition containing the above components exhibits excellent dispersion stability and handling properties. The excellent dispersion stability and handling properties are maintained even when the solid content concentration in the inorganic solid electrolyte-containing composition is increased. Furthermore, by using the inorganic solid electrolyte-containing composition of the present invention as a material for forming the constituent layers of an all-solid-state secondary battery, solid particles can be firmly bonded together, making it possible to realize an all-solid-state secondary battery with low resistance and excellent high-potential cycle characteristics.

[0015] Although the details of the reason are not yet clear, it is thought to be as follows: A binder containing a polymer (sometimes referred to as "the polymer of the present invention") that has a specific content of the constituent unit (D) described later and has a specific polar functional group can be appropriately adsorbed to solid particles in an inorganic solid electrolyte-containing composition, thereby suppressing (re)aggregation and precipitation of solid particles in the dispersion medium and enabling high dispersion. Therefore, even if the solid content concentration is increased, excellent initial dispersibility can be maintained over time, and even solid particles that have aggregated or precipitated can reproduce the excellent initial dispersibility immediately after preparation, and are thought to exhibit appropriate fluidity. In particular, if the polymer binder (B) shows solubility in the dispersion medium, the polymer binder dissolves in the dispersion medium, making it less prone to aggregation and adhesion, and further improving dispersibility. As a result, the polymer binder (B) with improved dispersibility can further improve the initial dispersibility and dispersion stability (collectively referred to as "dispersion properties") of the inorganic solid electrolyte-containing composition.

[0016] When a constituent layer is formed with such an inorganic solid electrolyte-containing composition, the uneven distribution of solid particles can be suppressed, and the solid particles can be firmly adhered (bound) to each other to construct sufficient conduction paths (ion conduction paths and electron conduction paths). Furthermore, it is believed that surface roughness caused by insufficient or excessive flow, as well as surface roughness caused by clogging of the dispensing part during coating, can be suppressed. Such a constituent layer can suppress the generation of overcurrent during charging and discharging of the all-solid-state secondary battery and prevent the degradation of solid particles. In addition, the polymer binder containing the polymer of the present invention solidifies while maintaining excellent dispersibility in the inorganic solid electrolyte-containing composition during drying after coating. Moreover, since polymer binder (B) contains a polymer that contains constituent units that satisfy the relationship represented by formulas (1) to (3) described later in a specific content, as described later, the binder polymer and polymer binder (B) itself are less prone to degradation, and it is believed that the adherence of solid particles can be maintained, preferably for a long period of time, even when the all-solid-state secondary battery is charged at a high potential. Therefore, the inorganic solid electrolyte-containing composition of the present invention makes it possible to manufacture a sheet for an all-solid-state secondary battery having a low-resistance constituent layer that exhibits excellent high-potential cycle characteristics when incorporated into an all-solid-state secondary battery, and also makes it possible to manufacture an all-solid-state secondary battery that exhibits both low resistance and excellent high-potential cycle characteristics. Furthermore, the all-solid-state secondary battery of the present invention also has excellent characteristics in maintaining battery capacity even when repeatedly charged at normal potentials (e.g., less than 4.4V) (referred to as "normal potential cycle characteristics" when distinguishing it from the high-potential cycle characteristics mentioned above). In the present invention, the term "cycle characteristics" simply includes both normal potential cycle characteristics and high-potential cycle characteristics.

[0017] The inorganic solid electrolyte-containing composition of the present invention is preferably a slurry in which solid particles are dispersed in a dispersion medium, particularly a high-concentration slurry. Furthermore, the inorganic solid electrolyte-containing composition of the present invention is preferably a non-aqueous composition. In the present invention, a non-aqueous composition includes not only a form that does not contain water, but also a form in which the water content (also called water content) is preferably 500 ppm or less. In a non-aqueous composition, the water content is more preferably 200 ppm or less, even more preferably 100 ppm or less, and particularly preferably 50 ppm or less. When the inorganic solid electrolyte-containing composition is a non-aqueous composition, the deterioration of the inorganic solid electrolyte can be suppressed. The water content indicates the amount of water contained in the inorganic solid electrolyte-containing composition (mass ratio to the inorganic solid electrolyte-containing composition), and specifically, it is the value measured by filtering with a 0.02 μm membrane filter and using Karl Fischer titration.

[0018] Because the inorganic solid electrolyte-containing composition of the present invention exhibits the above-mentioned excellent properties, it can be preferably used as a material for forming sheets for all-solid-state secondary batteries and constituent layers of all-solid-state secondary batteries. Among the constituent layers, it can be preferably used as a material for forming active material layers, particularly positive electrode active material layers and negative electrode active material layers containing negative electrode active material that expands and contracts significantly due to charging and discharging.

[0019] The inorganic solid electrolyte-containing composition of the present invention also includes embodiments that contain an active material in addition to the inorganic solid electrolyte (this embodiment of the composition is referred to as the "electrode composition"). The components contained in and that may be contained in the inorganic solid electrolyte-containing composition of the present invention will be described below.

[0020] [Inorganic Solid Electrolytes] The inorganic solid electrolyte-containing composition of the present invention contains an inorganic solid electrolyte. In the present invention, an inorganic solid electrolyte is an inorganic solid electrolyte, and a solid electrolyte is a solid electrolyte that can move ions within itself. Since inorganic solid electrolytes do not contain organic substances as the main ion-conducting material, they are clearly distinguished from organic solid electrolytes (polymer electrolytes represented by polyethylene oxide (PEO), and organic electrolyte salts represented by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), etc.). Furthermore, since inorganic solid electrolytes are solid in a steady state, they do not normally dissociate or become liberated into cations and anions. In this respect, inorganic electrolyte salts (LiPFSI) that dissociate or become liberated into cations and anions in the electrolyte or polymer are clearly distinguished from inorganic electrolyte salts (LiPFSI) that dissociate or become liberated into cations and anions in the electrolyte or polymer. ６ LiBF ４ It is clearly distinguishable from lithium bis(fluorosulfonyl)imide (LiFSI), LiCl, etc. The inorganic solid electrolyte is not particularly limited as long as it has conductivity for ions of metals belonging to Group 1 or Group 2 of the periodic table, and generally does not have electronic conductivity. When the all-solid-state secondary battery of the present invention is a lithium-ion battery, it is preferable that the inorganic solid electrolyte has ionic conductivity for lithium ions. The above inorganic solid electrolyte can be appropriately selected from solid electrolytes that are normally used in all-solid-state secondary batteries. For example, examples of inorganic solid electrolytes include (i) sulfide-based inorganic solid electrolytes, (ii) oxide-based inorganic solid electrolytes, (iii) halide-based inorganic solid electrolytes, and (iv) hydride-based inorganic solid electrolytes. In the present invention, sulfide-based inorganic solid electrolytes, which are generally prone to degradation and decomposition, can be used, and a better interface can be formed between solid particles, effectively suppressing the increase in interfacial resistance.

[0021] (i) Sulfide-based inorganic solid electrolyte The sulfide-based inorganic solid electrolyte preferably contains a sulfur atom, has ion conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and has electronic insulating properties. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S, and P as elements and has lithium ion conductivity, but may appropriately contain other elements other than Li, S, and P.

[0022] Examples of the sulfide-based inorganic solid electrolyte include a lithium ion conductive inorganic solid electrolyte satisfying the composition represented by the following formula (S1). L ａ１ M ｂ１ P ｃ１ S ｄ１ A ｅ１ (S1) In formula (S1), L represents an element selected from Li, Na, and K, and Li is preferable. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. A represents an element selected from I, Br, Cl, and F. a1 to e1 represent the composition ratio of each element, and a1:b1:c1:d1:e1 satisfies 1 to 12:0 to 5:1:2 to 12:0 to 10. a1 is preferably 1 to 9, more preferably 1.5 to 7.5. b1 is preferably 0 to 3, more preferably 0 to 1. d1 is preferably 2.5 to 10, more preferably 3.0 to 8.5. e1 is preferably 0 to 5, more preferably 0 to 3.

[0023] The composition ratio of each element can be controlled by adjusting the blending amount of raw material compounds when producing the sulfide-based inorganic solid electrolyte as described below.

[0024] The sulfide-based inorganic solid electrolyte may be amorphous (glass), crystallized (formed into glass-ceramics), or may be partially crystallized. For example, Li-P-S-based glass containing Li, P, and S, or Li-P-S-based glass-ceramics containing Li, P, and S can be used. The sulfide-based inorganic solid electrolyte is, for example, lithium sulfide (Li ２ S), phosphorus sulfide (for example, diphosphorus pentasulfide (P ２ S ５)), elemental phosphorus, elemental sulfur, sodium sulfide, hydrogen sulfide, lithium halides (e.g., LiI, LiBr, LiCl) and sulfides of the element represented by M above (e.g., SiS ２ SnS, GeS ２ It can be produced by the reaction of at least two or more raw materials in ).

[0025] In Li-P-S glass and Li-P-S glass ceramics, Li ２ S and P ２ S ５ The ratio to Li ２ S:P ２ S ５ The molar ratio is preferably 60:40 to 90:10, more preferably 68:32 to 78:22. Li ２ S and P ２ S ５ By setting the ratio within this range, the lithium ion conductivity can be increased. Specifically, the lithium ion conductivity is preferably set to 1 × 10⁻⁶. －４ S / cm or more, more preferably 1 × 10 －３ It can be S / cm or more. There is no particular upper limit, but 1 × 10 －１ It is practical for the ratio to be less than or equal to S / cm.

[0026] As a specific example of a sulfide-based inorganic solid electrolyte, an example of raw material combinations is shown below. For example, Li ２ S-P ２ S ５ Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ -H ２ S, Li ２ S-P ２ S ５ -H ２ S-LiCl, Li ２ S-LiI-P ２ S ５ Li ２ S-LiI-Li ２ O-P ２ S ５ Li ２ S-LiBr-P２ S ５ 、Li ２ S-Li ２ O-P ２ S ５ 、Li ２ S-Li ３ PO ４ -P ２ S ５ 、Li ２ S-P ２ S ５ -P ２ O ５ 、Li ２ S-P ２ S ５ -SiS ２ 、Li ２ S-P ２ S ５ -SiS ２ -LiCl、Li ２ S-P ２ S ５ -SnS、Li ２ S-P ２ S ５ -Al ２ S ３ 、Li ２ S-GeS ２ 、Li ２ S-GeS ２ -ZnS、Li ２ S-Ga ２ S ３ 、Li ２ S-GeS ２ -Ga ２ S ３ 、Li ２ S-GeS ２ -P ２ S ５ 、Li ２ S-GeS ２ -Sb ２ S ５ 、Li ２ S-GeS ２ -Al ２ S ３ 、Li ２ S-SiS ２ 、Li ２ S-Al ２ S ３ 、Li ２ S-SiS ２ -Al ２S ３ Li ２ S-SiS ２ -P ２ S ５ Li ２ S-SiS ２ -P ２ S ５ -LiI, Li ２ S-SiS ２ -LiI, Li ２ S-SiS ２ -Li ４ SiO ４ Li ２ S-SiS ２ -Li ３ PO ４ Li １０ GeP ２ S １２ These are some examples. However, the mixing ratio of each raw material is not specified. As a method for synthesizing sulfide-based inorganic solid electrolytes using such raw material compositions, one example is the amorphous method. Examples of amorphous methods include the mechanical milling method, the solution method, and the melt-quenching method. This is because processing at room temperature is possible, and the manufacturing process can be simplified.

[0027] (ii) Oxide-based inorganic solid electrolytes are preferably oxide-based inorganic solid electrolytes that contain oxygen atoms, have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and have electronic insulating properties. The oxide-based inorganic solid electrolyte has an ionic conductivity of 1 × 10⁻¹⁰. －６ It is preferable that the S / cm is greater than or equal to 5 × 10 －６ It is more preferable that the S / cm or higher is 1 × 10 －５ It is particularly preferable that the ratio be 1 / cm or higher. There is no particular upper limit, but 1 × 10 －１ It is practical for the ratio to be less than or equal to S / cm.

[0028] Specific examples of compounds include, for example, Li ｘａ La ｙａ TiO ３ [xa satisfies 0.3 ≤ xa ≤ 0.7, and ya satisfies 0.3 ≤ ya ≤ 0.7.] (LLT); Li ｘｂ La ｙｂ Zr ｚｂ Mｂｂ ｍｂ O ｎｂ (M ｂｂ is one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn. xb satisfies 5 ≤ ​​xb ≤ 10, yb satisfies 1 ≤ yb ≤ 4, zb satisfies 1 ≤ zb ≤ 4, mb satisfies 0 ≤ mb ≤ 2, and nb satisfies 5 ≤ ​​nb ≤ 20. ); Li ｘｃ B ｙｃ M ｃｃ ｚｃ O ｎｃ (M ｃｃ is one or more elements selected from C, S, Al, Si, Ga, Ge, In, and Sn. xc satisfies 0 < xc ≤ 5, yc satisfies 0 < yc ≤ 1, zc satisfies 0 < zc ≤ 1, and nc satisfies 0 < nc ≤ 6. ); Li ｘｄ (Al, Ga) ｙｄ (Ti, Ge) ｚｄ Si ａｄ P ｍｄ O ｎｄ (xd satisfies 1 ≤ xd ≤ 3, yd satisfies 0 ≤ yd ≤ 1, zd satisfies 0 ≤ zd ≤ 2, ad satisfies 0 ≤ ad ≤ 1, md satisfies 1 ≤ md ≤ 7, and nd satisfies 3 ≤ nd ≤ 13.) ; Li （３－２ｘｅ） M ｅｅ ｘｅ D ｅｅ O(xe represents a number between 0 and 0.1, M ｅｅ D represents a divalent metal atom. ｅｅ represents a halogen atom or a combination of two or more halogen atoms. ); Li ｘｆ Si ｙｆ O ｚｆ (xf satisfies 1 ≤ xf ≤ 5, yf satisfies 0 < yf ≤ 3, and zf satisfies 1 ≤ zf ≤ 10.) ; Li ｘｇ S ｙｇ O ｚｇ (xg satisfies 1 ≤ xg ≤ 3, yg satisfies 0 < yg ≤ 2, and zg satisfies 1 ≤ zg ≤ 10.) ; Li ３ BO ３ Li ３ BO ３ -Li ２ SO ４ Li ２ O-B２ O ３ -P ２ O ５ Li ２ O-SiO ２ Li ６ BaLa ２ Ta ２ O １２ Li ３ PO （４－３／２ｗ） N ｗ (where w < 1); Li having a LISICON (Lithium super ionic conductor) type crystal structure ３．５ Zn ０．２５ GeO ４ La having a perovskite crystal structure ０．５５ Li ０．３５ TiO ３ LiTi having a NASICON (Natrium super ionic conductor) type crystal structure ２ P ３ O １２ Li １＋ｘｈ＋ｙｈ (Al, Ga) ｘｈ (Ti, Ge) ２－ｘｈ Si ｙｈ P ３－ｙｈ O １２ (xh satisfies 0 ≤ xh ≤ 1, and yh satisfies 0 ≤ yh ≤ 1.) Li having a garnet-type crystal structure ７ La ３ Zr ２ O １２ Examples include (LLZ). Phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li ３ PO ４ LiPON; LiPOD １ (D １ The element is preferably one or more elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au. Other examples include LiA. １ ON (A １ (This is one or more elements selected from Si, B, Ge, Al, C, and Ga.) Other elements such as () can also be preferably used.

[0029] (iii) Halide-based inorganic solid electrolytes The halide-based inorganic solid electrolyte is preferably a compound that contains halogen atoms, has conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, and has electronic insulating properties. The halide-based inorganic solid electrolyte is not particularly limited, but for example, LiCl, LiBr, LiI, and Li as described in ADVANCED MATERIALS, 2018, 30, 1803075 ３ YBr ６ Li ３ YCl ６ Examples of such compounds include Li ３ YBr ６ Li ３ YCl ６ It is preferable.

[0030] (iv) Hydride-based inorganic solid electrolytes are preferably compounds that contain hydrogen atoms, have ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and have electronic insulating properties. There are no particular limitations on the hydride-based inorganic solid electrolyte, but for example, LiBH ４ Li ４ (BH ４ ) ３ I, 3LiBH ４ - Examples include LiCl, etc.

[0031] Inorganic solid electrolytes are preferably in particulate form in the inorganic solid electrolyte-containing composition. In the present invention, particulate form may be flattened, amorphous, etc., but spherical or granular form is preferred. When the inorganic solid electrolyte is in particulate form, the particle size (volume average particle size) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or larger, and more preferably 0.1 μm or larger. The upper limit is preferably 100 μm or less, and more preferably 50 μm or less. The particle size of the inorganic solid electrolyte is measured by the following procedure. Dilute the inorganic solid electrolyte particles with water (or heptane in the case of water-unstable substances) in a 20 mL sample bottle to prepare a 1% by mass dispersion. Irradiate the diluted dispersion sample with 1 kHz ultrasound for 10 minutes and use it for testing immediately thereafter. Using this dispersion sample, data acquisition is performed 50 times at a temperature of 25°C using a quartz cell with a laser diffraction / scattering particle size distribution analyzer LA-920 (product name, manufactured by HORIBA Corporation) to obtain the volume-average particle size. For other detailed conditions, refer to the description in Japanese Industrial Standard (JIS) Z 8828:2013 "Particle size analysis - Dynamic light scattering method" as needed. Five samples are prepared for each level and their average value is adopted.

[0032] The method for adjusting the particle size is not particularly limited, and known methods can be applied, such as using a conventional grinder or classifier. Suitable grinders or classifiers include, for example, mortars, ball mills, sand mills, vibrating ball mills, satellite ball mills, planetary ball mills, swirling airflow jet mills, or sieves. Wet grinding can be performed with a dispersion medium such as water or methanol present during grinding. Classification is preferable to obtain the desired particle size. Classification is not particularly limited and can be performed using sieves, wind classifiers, etc. Classification can be performed both dry and wet.

[0033] The inorganic solid electrolyte-containing composition may contain one or more types of inorganic solid electrolytes. The content of the inorganic solid electrolyte in the inorganic solid electrolyte-containing composition is not particularly limited, but in terms of the dispersion state of solid particles and resistance, it is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of solid content. As an upper limit, from a similar viewpoint, it is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and particularly preferably 99% by mass or less. However, if the inorganic solid electrolyte-containing composition contains an active material described later, it is preferable that the total content of the inorganic solid electrolyte in the inorganic solid electrolyte-containing composition, including the active material and the inorganic solid electrolyte, is within the above range. In the present invention, solid content (solid components) refers to components that do not volatilize or evaporate when the inorganic solid electrolyte-containing composition is dried at 150°C for 6 hours under a pressure of 1 mmHg and a nitrogen atmosphere. Typically, it refers to components other than the dispersion medium described later.

[0034] [Polymer Binder] The polymer binder contained in the inorganic solid electrolyte-containing composition of the present invention contains the polymer of the present invention as described later, and preferably has the property of dissolving in a dispersion medium as described later. The polymer of the present invention contained in the polymer binder may be one type or two or more types. In the present invention, "containing the polymer of the present invention" includes both forms: a binder consisting of the polymer of the present invention itself, and a binder comprising the polymer of the present invention and other components. Other components that may be contained in the binder are not particularly limited, but include polymers other than the polymer of the present invention, synthesis by-products of the polymer of the present invention, decomposition products (residues) of polymerization catalysts, residual synthesis solvents, etc. Examples of polymers other than the polymer of the present invention include polymer binders that are commonly used as binders for all-solid-state secondary batteries (in the present invention, these may be referred to as "other polymer binders"), and details will be described later. The content of the polymer of the present invention in the polymer binder is appropriately set within a range that achieves the effects of the present invention, and can be, for example, 90% by mass or more. On the other hand, the total content of other components in the polymer binder can be appropriately set within a range that does not impair the effects of the present invention, and can be, for example, 10% by mass or less.

[0035] In the inorganic solid electrolyte-containing composition of the present invention, the polymer binder (the polymer of the present invention contained in the polymer binder) is thought to exhibit the function of dispersing solid particles in a dispersion medium by adsorbing onto solid particles and interposing between solid particles. Here, the adsorption of the polymer binder onto solid particles is not particularly limited, but includes not only physical adsorption but also chemical adsorption (adsorption by chemical bond formation, adsorption by electron transfer, etc.). The dispersion properties and handling properties exhibited by the polymer binder are also exhibited even when the solid content concentration is increased. The solid content concentration in the inorganic solid electrolyte-containing composition of the present invention is not particularly limited, and can usually be 20 to 80% by mass at 25°C, preferably 30 to 75% by mass, and more preferably 40 to 70% by mass. On the other hand, the inorganic solid electrolyte-containing composition of the present invention can also be a high-concentration composition with a higher solid content concentration than conventional compositions. For example, the lower limit of the solid content concentration of the high-concentration composition can be set to 50% by mass or more at 25°C, for example, 60% by mass or more. The upper limit is less than 100% by mass, for example, it can be 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0036] On the other hand, the polymer binder (the polymer of the present invention) functions as a binder that firmly binds solid particles together in a constituent layer formed from an inorganic solid electrolyte-containing composition. Furthermore, it also functions as a binder that firmly binds solid particles to a substrate such as a current collector. Note that in the inorganic solid electrolyte-containing composition, the polymer binder may or may not have the function of binding solid particles together.

[0037] <Polymer of the Present Invention> The polymer contained in the polymer binder (the polymer of the present invention) has at least one polar functional group (sometimes referred to as "polar functional group (a)" for convenience) selected from the following functional group (a) in its molecular structure. By having polar functional group (a) in the polymer of the present invention, the dispersion characteristics and handling properties of the inorganic solid electrolyte-containing composition can be improved without impairing the above-mentioned excellent improvement of cycle characteristics, and furthermore, the adhesion of solid particles in the solid electrolyte layer can also be improved.

[0038] The polar functional group (a) is preferably present in the molecular chain that forms the side chain of the polymer of the present invention, and more preferably incorporated into the interior or end of the molecular chain that forms the side chain of the polymer of the present invention. However, if the side chain of the polymer of the present invention has a polymerization chain, the polar functional group present in the substructure that connects this polymerization chain and the main chain of the polymer is not included in the polar functional group (a) because it does not sufficiently improve adhesion. In the present invention, the molecular chain that forms the side chain of the polymer of the present invention refers to the molecular chain that constitutes the side chain of the polymer of the present invention, and is a molecular chain other than the molecular chain that constitutes the main chain of the polymer of the present invention, and is usually a molecular chain that is bonded to the molecular chain (group of atoms) that constitutes the main chain.

[0039] The polymer of the present invention only needs to have at least one polar functional group (a), and it is generally preferable to have one to three polar functional groups. The content (mass%) and number of polar functional groups (a) in the polymer of the present invention are not particularly limited and can be appropriately determined depending on the type and content of each constituent unit, the number of polar functional groups in each constituent unit, the content of constituent units having polar functional groups, the weight-average molecular weight of the polymer of the present invention, etc.

[0040] <Functional group (a)> Sulfonic acid group (sulfo group), phosphate group (phosphoryl group), phosphonic acid group, hydroxyl group, carboxyl group, dicarboxylic acid group, thiol group (sulfanyl group), ether group, ester group, amide group, urethane group, urea group, imide group and salts thereof

[0041] The sulfonic acid group, phosphoric acid group, phosphonic acid group, etc., included in functional group (a) are not particularly limited, but are synonymous with the corresponding group of substituent Z described later. The dicarboxylic acid group is not particularly limited, but includes groups obtained by removing one or more hydrogen atoms from a dicarboxylic acid or its anhydride, and the constituent unit itself obtained by copolymerizing a polymerizable dicarboxylic acid or its anhydride as a polymerizable compound, and further includes groups obtained by cleaving the anhydride group when a dicarboxylic acid or its anhydride reacts with an active hydrogen compound. As for the group obtained by removing one or more hydrogen atoms from a dicarboxylic acid or its anhydride, groups obtained by removing one or more hydrogen atoms from an acyclic dicarboxylic acid or a cyclic dicarboxylic acid anhydride are preferred. Examples of dicarboxylic acid anhydrides include acyclic dicarboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and benzoic anhydride, and cyclic dicarboxylic acid anhydrides such as maleic anhydride, phthalic anhydride, fumaric anhydride, succinic anhydride, and itaconic anhydride. The polymerizable dicarboxylic acid or its anhydride is not particularly limited, but examples include dicarboxylic acids or their anhydrides having an unsaturated bond in the molecule, and is preferably a polymerizable cyclic dicarboxylic acid anhydride. Examples of polymerizable dicarboxylic acids include maleic acid and itaconic acid, and examples of polymerizable cyclic dicarboxylic acid anhydrides include maleic acid and itaconic acid. The active hydrogen compound is not particularly limited as long as it is a compound that reacts with the dicarboxylic acid anhydride group, and examples include alcohol compounds, amine compounds, and thiol compounds.

[0042] Ether group (-O-), ester group (*-CO-O-**), amide group (*-CONR ＮＡ１ -**), urethane group (*-NR ＮＡ１ -CO-O-**), urea group (-NR ＮＡ１ -CO-NR ＮＡ１ -), imide group (*-CO-NR ＮＡ２ -CO-**) represents the combination shown in parentheses. Here, * and ** indicate the joining part, R ＮＡ１ R represents a hydrogen atom or substituent. ＮＡ２ R represents a bond, hydrogen atom, or substituent. ＮＡ１ and R ＮＡ２The substituents that can be used are not particularly limited, but for example, groups selected from substituent Z described later can be listed, and alkyl groups (including cycloalkyl groups), aryl groups, heterocyclic groups, etc. are preferred. The number of carbon atoms in the alkyl group is preferably 1 to 20, and more preferably 1 to 12. The alkyl group can be a short-chain alkyl group or a long-chain alkyl group, as described later. The number of carbon atoms in the aryl group is preferably 6 to 26, more preferably 6 to 20, and even more preferably 6 to 12. Note that the two R groups in the urea group ＮＡ１ They may be the same or different. ＮＡ１ A hydrogen atom is preferred, R ＮＡ２ Hydrogen atoms or alkyl groups are preferred. In each of the above groups, either of the two bonding sites * and ** may be bonded to the main chain side of the polymer of the present invention, but it is preferable that bonding site * is bonded to the main chain side of the polymer of the present invention. In the case of the imide group, it is preferable that the two bonding sites * and ** are bonded to the main chain side of the polymer of the present invention and form a ring structure together with the atoms constituting the main chain. The ether group may also be an alkylene oxy group (for example, a 2-methoxyethoxy group) in which a plurality of alkylene groups are linked together via an alkylene group or the like. The number of carbon atoms in the alkylene group is not particularly limited, but for example, 1 to 20 is preferred, 1 to 12 is more preferred, 1 to 6 is even more preferred, and 1 to 3 is particularly preferred.

[0043] The terminal groups bonded to each of these groups are not particularly limited and represent hydrogen atoms or substituents. Examples of substituents that can be taken as terminal groups include those selected from substituent Z described later. Among these, alkyl groups (including cycloalkyl groups), aryl groups, and heterocyclic groups are preferred, with alkyl groups or aryl groups being more preferred. While there are no particular limitations on the substituents such as alkyl groups that can be taken as terminal groups, R ＮＡ１ It is preferable that it is synonymous with each substituent such as an alkyl group that can be taken as R. ＮＡ１ If either the terminal group or the other group takes a hydrogen atom, this hydrogen atom is R ＮＡ１ It is interpreted as follows.

[0044] In the present invention, the groups exhibiting the above-mentioned bonding, such as ether groups, include those that directly bond to the molecular chains constituting the main chain of the polymer of the present invention, for example, the carbon-carbon double bond polymerization chain described later. However, the ester group is bonded to the molecular chains constituting the main chain of the polymer of the present invention via a linking group, and does not include ester groups that directly bond to the molecular chains constituting the main chain of the polymer of the present invention. The linking group that connects the molecular chain and the ester group is not particularly limited, and any of the linking groups described later can be applied.

[0045] Note that ether groups are included in carboxyl groups, hydroxyl groups, dicarboxylic acid anhydride groups, ester groups, etc., but the -O- group contained in these is not considered an ether group. Also, ester groups are included in urethane groups, but the -CO-O- group contained in them is not considered an ester group. Furthermore, amide groups are included in urethane groups, urea groups, imide groups, etc., but the -CO-N group contained in these is not considered an ether group. ＲＮＡ１ - The group is not interpreted as an amide group. Polar functional groups may form cyclic structures. For example, an ether group may form a cyclic ether group, specifically an epoxy group, an oxetane group, or a tetrahydrofuranyl group. Also, an imide group may form a cyclic imide group, specifically a cyclic imide group derived from maleimide or phthalimide.

[0046] Groups that can form salts, such as sulfonic acid groups (sulfo groups), phosphoric acid groups, phosphonic acid groups, hydroxyl groups, carboxyl groups, and dicarboxylic acid groups, may also form salts with cations. The cations are not particularly limited and include various metal salts, ammonium or amine salts, etc. In addition, amide groups, urethane groups, urea groups, imide groups, etc., may also form salts with anions. The anions are not particularly limited and include various inorganic or organic acid anions, etc.

[0047] The polar functional groups of the polymer of the present invention are preferably sulfonic acid groups, phosphoric acid groups, phosphonic acid groups, hydroxyl groups, carboxyl groups, dicarboxylic acid groups, ether groups, amide groups, imide groups, or salts thereof. Hydroxyl groups, ether groups, amide groups, and imide groups are more preferred in terms of dispersion properties, adhesion, resistance, and cycling properties. In addition to dispersion properties, adhesion, resistance, and cycling properties, amide groups or imide groups are even more preferred because they tend to satisfy the relationships represented by the above formulas (1) to (3) and can also improve high-potential cycling properties.

[0048] A method for introducing the above polar functional groups into the polymer of the present invention will be described later.

[0049] (Constituent Unit (D)) The polymer of the present invention has constituent units (D) as essential constituent units (also called constituent components) that satisfy all the relationships expressed by the following formulas (1) to (3). Furthermore, the polymer of the present invention has a content of the above constituent units (D) of 80% by mass or more in relation to the total mass of the polymer. The polymer of the present invention only needs to have constituent units (D) in a specific content, and may have constituent units that do not correspond to constituent units (D). Formula (1): -8.3 ≤ E ≤ -6.3 Formula (2): 0.2 ≤ σ ≤ 1.2 Formula (3): σ ≤ 1.0 × E + 8.8 In the above formulas, E represents the energy level (eV) of the highest occupied orbital (HOMO) in the constituent unit, and σ represents the maximum value of the positive charge on the carbon atom calculated by Merz-Kollman electrostatic potential fitting in the constituent unit.

[0050] - Relationship expressed by formula (1): Energy level of the highest occupied orbital - The constituent unit (D) contained in the polymer of the present invention has an energy level of the highest occupied orbital (HOMO) that is in the range of -8.3 eV to -6.3 eV, according to the relationship expressed by formula (1). By satisfying the relationship expressed by formula (1), the constituent unit (D), in combination with the relationships expressed by formula (2) or formula (3) described later, can suppress the degradation of the binder polymer and the polymer binder (B) itself, and improve the cycle characteristics of the all-solid-state secondary battery, especially the high-potential cycle characteristics, while maintaining dispersion stability, handling properties, and adhesion. Specifically, when the energy level of the constituent unit (D) is -6.3 eV or lower, the oxidation resistance of the constituent unit (D) is increased, and the oxidative degradation of the polymer and polymer binder of the present invention can be suppressed, preferably over a long period of time. In order to highly suppress oxidative degradation of the polymer binder and further enhance the cycle characteristics, especially high-potential cycle characteristics, the energy level of the constituent unit (D) is preferably -6.6 eV or lower, and more preferably -6.9 eV or lower. On the other hand, if the energy level of the constituent unit (D) is -8.3 eV or higher, the dispersion characteristics are improved, and the handling properties of the inorganic solid electrolyte-containing composition are also improved. In order to exhibit a good balance of dispersion characteristics, handling properties, adhesion, and cycle characteristics, the energy level of the constituent unit (D) is preferably -8.0 eV or higher, and more preferably -7.7 eV or higher.

[0051] The energy levels of HOMO and the maximum positive charge of the carbon atom in equation (2) were calculated as follows. Specifically, they were calculated by performing a DFT calculation using the quantum chemistry calculation software Gaussian 16. The structure used for the calculation is the monomer structure, which is the smallest repeating unit in the polymer, in which the polymerizable double bond is opened and terminated with a methyl group. For example, for styrene monomer, the following structure is used for the calculation. If the constituent unit has a polymerization chain (a chain with a repeating structure) in its side chain, the structure used for the calculation is the structure in which the bond connecting to the polymerization chain is broken and replaced with a hydrogen atom (a structure in which the polymerization chain is replaced with a hydrogen atom). Specifically, this is as described in the section below regarding the constituent unit MM-1 in the comparative example polymer BT-5.

[0052]

[0053] Structural optimization is performed using the quantum chemistry calculation software Gaussian16 with DFT(B3LYP / 6-31+G(d,p) / scrf=(solvent=water)). The initial structure (conformation) used for structural optimization is such that the dihedral angles of atoms (excluding hydrogen atoms) in linear chain portions connected by single bonds, such as alkyl chains and ether chains, are 180°. For the structure obtained from the above structural optimization that yields the most stable total energy, point charges on atoms fitted to the HOMO energy calculated with DFT(B3LYP / 6-31+G(d,p) / scrf=(solvent=water)) and the Merz-Kollmann electrostatic potential obtained with the pop=mk option are acquired. The HOMO energy Ehartree (unit: Hartree) obtained from the above calculation is converted to E (unit: eV), which is used as the value of HOMO energy in this invention, using the following formula: E(eV) = 27.2114 × Ehartree

[0054] The energy level of the HOMO can be adjusted, for example, by the type of constituent unit (D), chemical structure, substituents, etc. For example, methacrylic acid ester compounds, acrylamide compounds, maleimide compounds, styrene compounds, etc., can lower (deepen) the energy level of the HOMO. In the case of methacrylic acid ester compounds, selecting an alkyl ester compound, preferably a long-chain alkyl ester compound, or an alkyl ester compound having at least one polar functional group from the functional group group (a) described later (preferably a short-chain alkyl ester compound described later) can lower the energy level of the HOMO. Here, the long-chain alkyl group that forms the long-chain alkyl ester compound and the short-chain alkyl group that forms the short-chain alkyl ester compound are as described later. On the other hand, if an acrylic acid ester compound is selected, or even if it is a methacrylic acid ester compound, if it is an alkyl ester compound having substituents such as an amino group or an ether group, the energy level of the HOMO tends to be higher (shallower). Acrylamide compounds tend to have a low HOMO energy level, but this tendency is even stronger when the nitrogen atom in the amide bond is monosubstituted or disubstituted, and the HOMO energy level is further lowered when the nitrogen atom in the amide bond is monosubstituted. The substituent that substitutes the nitrogen atom is not particularly limited. For example, selecting an alkyl group as the substituent can further lower the HOMO energy level. Maleimide compounds also tend to have a low HOMO energy level, but the HOMO energy level can be further lowered when the nitrogen atom in the imide bond has a substituent. The substituent is not particularly limited, but an alkyl group can further lower the HOMO energy level. In styrene compounds, the HOMO energy level tends to be low when unsubstituted.

[0055] - Relationship expressed by formula (2): Maximum value of positive charge of carbon atom - The constituent unit (D) contained in the polymer of the present invention has a maximum value of positive charge on a carbon atom calculated by Merz-Kollman electrostatic potential fitting (in the present invention, this may simply be referred to as "maximum positive charge of carbon atom") that is within the range of 0.2 to 1.2, as shown in formula (2). By satisfying the relationship expressed by formula (2), the constituent unit (D), in combination with the relationships expressed by formula (1) or formula (3) described later, can suppress the degradation of the binder polymer and the polymer binder (B) itself, and improve the cycle characteristics of the all-solid-state secondary battery, especially the high-potential cycle characteristics, while maintaining dispersion stability, handling properties, and adhesion. Specifically, if the maximum positive charge of the carbon atom of the constituent unit (D) is 1.2 or less, the constituent unit (D) becomes more resistant to nucleophilic attack (nucleophilic reaction), and the degradation of the polymer and polymer binder of the present invention can be suppressed, preferably over a long period of time. In order to highly suppress degradation of the polymer binder against nucleophilic attack and further enhance the cycle characteristics, especially high-potential cycle characteristics, the maximum positive charge of the carbon atom is preferably 1.0 or less, and more preferably 0.8 or less. On the other hand, if the maximum positive charge of the carbon atom is 0.2 or more, the dispersion characteristics improve, and the handling properties of the inorganic solid electrolyte-containing composition also tend to improve. In order to exhibit a good balance of dispersion characteristics, handling properties, adhesion, and cycle characteristics, the maximum positive charge of the carbon atom is preferably 0.3 or more, and more preferably 0.4 or more. The relationship expressed by formula (2) is preferably expressed by the following formula (2A). Note that if there are multiple maximum values ​​of positive charge on carbon atoms in the constituent unit, each value shall be considered the maximum value. Formula (2A): 0.4 ≤ σ ≤ 1.2

[0056] As described above, the maximum positive charge of a carbon atom is calculated using DFT calculations with the quantum chemistry software Gaussian 16. Specifically, the largest point charge on a carbon atom among the point charges obtained on atoms as described above is selected and designated as the "maximum positive charge of a carbon atom."

[0057] The maximum positive charge of a carbon atom can be adjusted by, for example, the type of constituent unit (D), chemical structure, substituents, etc. For example, methacrylic acid ester compounds, acrylamide compounds, maleimide compounds, styrene compounds, etc., can reduce the maximum positive charge of a carbon atom. In the case of methacrylic acid ester compounds, selecting an alkyl ester compound, preferably a long-chain alkyl ester compound described later, or an alkyl ester compound having at least one polar functional group from the functional group group (a) described later (preferably a short-chain alkyl ester compound described later) can reduce the maximum positive charge of a carbon atom. On the other hand, selecting an acrylic acid ester compound, or even a methacrylic acid ester compound, if it is an alkyl ester compound having substituents such as a cyclic alkyl group or a hydroxyl group near the carbon atom with the maximum positive charge, tends to reduce the maximum positive charge of a carbon atom. Acrylamide compounds tend to reduce the maximum positive charge of a carbon atom, but if the nitrogen atom in the amide bond is monosubstituted or disubstituted, the tendency to reduce the maximum positive charge of a carbon atom is stronger, and if the nitrogen atom in the amide bond is monosubstituted, the maximum positive charge of a carbon atom becomes even smaller. The substituents that substitute for the nitrogen atom are not particularly limited. For example, selecting an alkyl group as the substituent can further reduce the maximum positive charge of the carbon atom. In acrylamide compounds, introducing an electron-withdrawing group near the carbon atom with the maximum positive charge tends to increase the maximum positive charge of the carbon atom. Maleimide compounds tend to have a smaller maximum positive charge of the carbon atom, but if the nitrogen atom in the imide bond has a substituent, the maximum positive charge of the carbon atom can be further reduced. The substituent is not particularly limited, but if it is an alkyl group, the maximum positive charge of the carbon atom can be further reduced. In maleimide compounds, introducing an electron-withdrawing group near the carbon atom with the maximum positive charge tends to increase the maximum positive charge of the carbon atom. In styrene compounds, if unsubstituted, the maximum positive charge of the carbon atom tends to increase.

[0058] - Relationship expressed by equation (3): Relationship between the energy level of HOMO and the maximum positive charge of carbon atoms - As shown in Figure 3, the constituent unit (D) contained in the polymer of the present invention exhibits a linear relationship between the energy level of HOMO and the maximum positive charge of carbon atoms, which is expressed by equation (3), i.e., σ ≤ 1.0 × E + 8.8. By satisfying the relationship expressed by equation (3), the constituent unit (D), in combination with the relationships expressed by equation (1) or equation (2) above, can suppress the degradation of the binder polymer and the polymer binder (B) itself, and improve the cycle characteristics of the all-solid-state secondary battery, especially the high-potential cycle characteristics, while maintaining dispersion stability, handling properties, and adhesion. In terms of being able to greatly improve high-potential cycle characteristics while maintaining dispersion stability, handling properties, and adhesion, the relationship expressed by equation (3) is preferably the relationship expressed by the following equation (3A), and more preferably the relationship expressed by the following equation (3B). Formula (3A): σ≦1.0×E+8.5 Formula (3B): σ≦1.0×E+8.2

[0059] The relationship expressed by equation (3) was derived as follows, based on the results of the examples and comparative examples described later. First, as shown in Figure 3, the energy levels of HOMO and the maximum positive charge of carbon atoms in each constituent unit of the polymer used in each example and comparative example are plotted in a Cartesian coordinate system (XY coordinate system) with the energy level of HOMO as the X axis and the maximum positive charge of carbon atoms (simply referred to as "charge" in Figure 3) as the Y axis. Next, at least two constituent units that satisfy the objectives of the present invention, particularly the cycle properties, are selected, and a virtual straight line (proportional relationship) L1 is assumed to connect these plots. The slope of this virtual straight line L1 is determined and used as the slope of equation (3) above. In this invention, LMA (n-dodecyl methacrylate) and DMA (n-decyl methacrylate) were selected as constituent units to determine the slope. The reasons for selecting these two constituent units are as follows. First, in Figure 3, we selected LMA (n-dodecyl methacrylate), which is the nearest neighbor to Comparative Example LA (n-dodecyl acrylate) that does not satisfy the objectives of the present invention, from among the Examples that do satisfy the objectives of the present invention. We considered that the Examples and Comparative Examples could be distinguished by drawing a straight line with a positive slope that passes through the midpoint between these two points. In order to uniquely determine the slope of the straight line, we decided to select the plot with the maximum slope. That is, in Figure 3, from among the Examples that satisfy the objectives of the present invention, we selected DMA (n-decyl methacrylate) as the plot that passes through LMA and has the maximum slope.

[0060] Next, a virtual line L2 passing through the midpoint between an embodiment that satisfies the objectives of the present invention and a comparative example that does not satisfy the objectives of the present invention, and having the above-mentioned slope, is assumed, and the intercept of this virtual line L2 is found and used as the intercept of equation (3) above. That is, the virtual line L1 is translated along the X-axis to a position that passes through the above-mentioned midpoint to identify the virtual line L2. In this invention, the constituent unit LMA (n-dodecyl methacrylate) of polymer B-13 used in Example 13 and the constituent unit LA (lauryl acrylate) of polymer BT-5 used in Comparative Example 5 were selected as the embodiment and comparative example to find the intercept. The reason for selecting LMA (n-dodecyl methacrylate) is that, in Figure 3, it is the nearest embodiment plot to the plot of constituent unit LA (lauryl acrylate), which is a representative comparative example. For the intercept of formula (3A), the constituent unit CyHMA (cyclohexyl methacrylate) of polymer B-7 used in Example 7, which exhibits superior performance and is the problem that the present invention aims to solve, and the nearest constituent unit DMA (n-decyl methacrylate) to CyHMA were selected, and the intercept was determined according to the method described above. For the intercept of formula (3B), the constituent unit LAAm (N-dodecylacrylamide) of polymer B-9 used in Example 9, which exhibits even superior performance and is the problem that the present invention aims to solve, and the nearest constituent unit DEGMEM: 2-(2-methoxyethoxy)ethyl methacrylate to LAAm were selected, and the intercept was determined according to the method described above.

[0061] In a preferred embodiment of the present invention, the relationship represented by formula (3A) may also be represented by the following formula (3A1), and the relationship represented by formula (3B) may also be represented by the following formula (3B1). The intercept in the relationship represented by formula (3A1) is a virtual line having the above slope and passing through the plot of the constituent unit CyHMA of polymer B-7. The intercept in the relationship represented by formula (3B1) is a virtual line having the above slope and passing through the plot of the constituent unit LAAm of polymer B-9. Formula (3A1): σ ≤ 1.0 × E + 8.4 Formula (3B1): σ ≤ 1.0 × E + 8.0

[0062] The relationship in (3) above can be adjusted by appropriately selecting the method for adjusting the energy levels of HOMO in (1) above and the method for adjusting the maximum positive charge of the carbon atom in equation (2) above, and combining the appropriately selected adjustment methods.

[0063] The constituent unit (D) is not particularly limited as long as it satisfies the relationships represented by the above formulas (1) to (3), and for example, a constituent unit derived from a polycondensable compound can be cited. The polycondensable compound can be any compound having a polycondensable group, and may consist of a polycondensable group, a terminal substituent, and a linking group L that appropriately links the polycondensable group and the terminal substituent. Ａ２ It is preferable that the compound has the above characteristics, and it is more preferable that it is a low molecular weight compound or does not have a repeating structure (polymerization chain).

[0064] The polycondensing group is appropriately determined according to the main chain structure of the polymer of the present invention. For example, if the polymer of the present invention is a stepwise polymer, a condensing functional group is selected, and if the polymer of the present invention is a chain polymer, a polymerizable group (ethylenically unsaturated group) is selected. An example of an ethylenically unsaturated group is a vinyl group. Here, stepwise polymers include polymers obtained by polycondensation, polyaddition, or addition condensation of raw material compounds, such as polyurethanes, polyureas, polyamides, polyimides, polyesters, polysiloxanes, or copolymers thereof. For chain polymers, examples include polymers having a polymerization chain of carbon-carbon double bonds as the main chain, such as hydrocarbon polymers, vinyl polymers, (meth)acrylic polymers, or copolymers thereof, with (meth)acrylic polymers being preferred. In the present invention, (meth)acrylic polymer refers to a polymer consisting of a (co)polymer containing 50% by mass or more of structural units derived from, for example, the (meth)acrylic compound (M1) described later, and vinyl polymer refers to a copolymer containing 50% by mass or more of structural units derived from, for example, the vinyl compound (M2) described later (provided that the content of structural units derived from the (meth)acrylic compound (M1) is less than 50% by mass).

[0065] The terminal substituent is not particularly limited, but examples include a group selected from substituent Z described later, or the polar functional group (a) described above. Examples of groups selected from substituent Z include alkyl groups, alkenyl groups, aryl groups, heterocyclic groups, etc., with alkyl groups being preferred. Examples of alkyl groups that can be taken as terminal substituents include alkyl groups that constitute (meth)acrylate alkyl ester compounds. In the constituent unit (Da) described later, it is preferable that the terminal substituent is a polar functional group (a).

[0066] Linking group L Ａ２ The elements are not particularly limited, but include, for example, alkylene groups (preferably with 1 to 12 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3 carbon atoms), alkenylene groups (preferably with 2 to 6 carbon atoms, more preferably 2 to 3 carbon atoms), arylene groups (preferably with 6 to 24 carbon atoms, more preferably 6 to 10 carbon atoms), oxygen atoms, sulfur atoms, and imino groups (-NR Ｎ -: R Ｎ L represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Other examples include carbonyl groups, phosphate linking groups (-O-P(OH)(O)-O-), phosphonic acid linking groups (-P(OH)(O)-O-), or groups related to combinations thereof. However, linking group L Ａ２ It is preferable that the linking group L is not a group corresponding to each of the polar functional groups (a) described above. Ａ２ Preferably, the group is a combination of an alkylene group, an arylene group, a carbonyl group, an oxygen atom, a sulfur atom, and an imino group, and more preferably a combination of an alkylene group, an arylene group, a carbonyl group, an oxygen atom, a sulfur atom, and an imino group, such as a -CO-O- group or -CO-NR Ｎ - group, -NR Ｎ -CO-NR Ｎ - is preferable. R Ｎ This is as stated above.

[0067] The above connecting base L Ａ２ The number of atoms constituting it is preferably 1 to 36, more preferably 1 to 24, and even more preferably 1 to 12. Linking group L Ａ２The number of linked atoms is preferably 12 or less, more preferably 10 or less, and particularly preferably 8 or less. The lower limit is 1 or more. The above number of linked atoms refers to the minimum number of atoms connecting a given structural part. For example, -O-C(=O)-CH ２ -CH ２ - In this case, the number of atoms constituting the linking group becomes 9, but the number of linked atoms becomes 4. In the constituent unit (Da) described later, the terminal substituent into which the polar functional group (a) is introduced is the linking group L Ａ２ In cases where this can also be considered, this terminal substituent is a linking group L Ａ２ Instead, it should be interpreted as a terminal substituent into which a polar functional group (a) is introduced.

[0068] The polycondensable compounds that derive the constituent unit (D) include, specifically, the following groups of compounds: (meth)acrylic compounds (M1) such as (meth)acrylic acid compounds, (meth)acrylic acid ester compounds, (meth)acrylamide compounds, and (meth)acrylonitrile compounds; vinyl compounds (M2) such as styrene compounds, vinylnaphthalene compounds, vinylcarbazole compounds, allyl compounds, vinyl ester compounds, vinyl ether compounds, cyclic olefin compounds, diene compounds, and vinyl carboxylate ester compounds; dialkyl itaconic acid monomers; and; maleimide compounds, N-vinyl substituted imide compounds, and vinyl succimide compounds.

[0069] Among the polycondensable compounds used to derive the constituent unit (D), methacrylic acid ester compounds, (meth)acrylamide compounds, styrene compounds, maleimide compounds, etc. are preferred because they easily satisfy (and are easily adjusted to) the relationships represented by formulas (1) to (3). (Meth)acrylamide compounds and maleimide compounds are more preferred because they satisfy the relationships represented by formulas (1) to (3) and maintain excellent dispersion properties, handling properties, and adhesion properties while further enhancing high-potential cycling properties. In other words, it is more preferable that the constituent unit (D) includes a constituent unit derived from a (meth)acrylamide compound or a constituent unit derived from a maleimide compound.

[0070] Examples of (meth)acrylic acid ester compounds include (meth)acrylate alkyl ester compounds and (meth)acrylate aryl ester compounds, with (meth)acrylate alkyl ester compounds being preferred and methacrylate alkyl ester compounds being more preferred. The alkyl group constituting the (meth)acrylate alkyl ester compound may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, with linear alkyl groups or cyclic alkyl groups being preferred. The number of carbon atoms in the alkyl group constituting the (meth)acrylate alkyl ester compound is not particularly limited and can be, for example, 1 to 24, but it is preferable to determine it considering the satisfaction of the relationships represented by the above formulas, the solubility of the polymer of the present invention in the dispersion medium, and the adhesion to solid particles. Focusing on the satisfaction of the relationships represented by the above formulas and solubility, a long-chain alkyl group is preferred as the alkyl group, and the number of carbon atoms of the long-chain alkyl group is preferably 4 to 24, more preferably 6 to 20, and even more preferably 8 to 14. On the other hand, focusing on the satisfaction and adhesion of the relationships represented by the above formulas (particularly the constituent units (Da) described later), short-chain alkyl groups are preferred as alkyl groups, and the number of carbon atoms in the short-chain alkyl groups is preferably 1 to 3. When the alkyl group is a cyclic alkyl group, the lower limit of the number of carbon atoms is preferably 6. The number of carbon atoms in the aryl group constituting the aryl ester is not particularly limited, but can be, for example, 6 to 24, preferably 6 to 10, and more preferably 6.

[0071] The (meth)acrylamide compound is not particularly limited, and examples include (meth)acrylamide compounds such as N-unsubstituted (meth)acrylamide compounds and N-mono or disubstituted (meth)acrylamide compounds. Specifically, N-unsubstituted (meth)acrylamide compounds, N-alkyl (meth)acrylamide compounds, N,N-dialkyl (meth)acrylamide compounds, N-aryl (meth)acrylamide compounds, and N,N-diaryl (meth)acrylamide compounds are preferred. As substituents that substitute for the nitrogen atom in the acrylamide compound, R ＮＡ１Alternatively, terminal groups bonded to the ends of the amide bond included in the functional group group (a) are also included, and alkyl groups or aryl groups are preferred. As (meth)acrylamide compounds, compounds that derive a structural unit represented by the following formula (A1) are also preferred.

[0072]

[0073] In the above formula (A1), X １ X represents a hydrogen atom or substituent. １ The substituents that can be taken are not particularly limited, and can be selected from substituent Z described later, with alkyl groups being preferred. １ A hydrogen atom or a methyl group is preferred.

[0074] L １ L represents a single bond or a linking group, with a single bond being preferred. １ The linking group that can be adopted is not particularly limited, and the above linking group L Ａ２ It can be applied without any particular restrictions. However, L １ The linking groups that can be adopted as such will not form a urethane group, a urea group, or an imide group together with the amide group in formula (A1).

[0075] Y １ and Y ２ Each of these represents either a hydrogen atom or a substituent. １ and Y ２ The substituents that can be taken as are not particularly limited, and the above R ＮＡ１ Alternatively, it is synonymous with the terminal group attached to the end of the amide bond in the functional group (a), Y １ Hydrogen atoms are preferred, Y ２ It is preferable that Y is an alkyl group. However, Y １ and Y ２ The substituents that can be chosen as such will not form an imide group together with the amide group in formula (A1). １ and Y ２ They may be the same or different from each other. Y １ and Y ２ If both are alkyl groups, Y １ and Y ２ The alkyl group that can be taken as is the above RＮＡ１ Alternatively, an embodiment that is synonymous with an alkyl group that can be adopted as a terminal group bonded to the end of the amide bond included in the functional group (a) is preferred, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, a linear or branched octyl group, a linear or branched dodecyl group, etc. １ and Y ２ The alkyl group that can be used may have substituents. Examples of substituents include groups selected from substituent Z described later, and the polar functional group (a) is preferred in terms of adhesion. １ and Y ２ The combinations of alkyl groups that can be used are not particularly limited, and the alkyl groups listed above can be combined as appropriate.

[0076] The constituent unit represented by formula (A1) may have substituents. For example, in formula (A1), X １ A carbon atom bonded to a carbon atom having a methylene group is an unsubstituted carbon atom (methylene group: -CH ２ Although it is represented as -), it may have substituents. Such substituents are not particularly limited, but for example, X １ The above substituents can be adopted as such.

[0077] The styrene compound is not particularly limited and includes unsubstituted styrene and substituted styrene compounds. The substituent that substitutes the carbon atom of the benzene ring in the substituted styrene compound is not particularly limited and can be selected from substituent Z described later, for example, and the polar functional group (a) is preferred in terms of adhesion.

[0078] The maleimide compound is not particularly limited as long as it is a compound having a maleimide structure, and examples include N-unsubstituted maleimide compounds and N-substituted maleimide compounds, with N-substituted maleimide compounds being preferred. Specifically, N-alkylmaleimide compounds and N-arylmaleimide compounds are preferred, and N-alkylmaleimide compounds are more preferred. In N-alkylmaleimide compounds, the substituent that substitutes the nitrogen atom of the imide bond is the above R ＮＡ２Alternatively, examples include terminal groups bonded to the end of the imide bond in the functional group group (a), and alkyl groups are preferred. The alkyl group that substitutes the nitrogen atom is preferably the same as the alkyl group that constitutes the (meth)acrylate alkyl ester compound.

[0079] The constituent unit (D) may have substituents as long as it satisfies the relationships represented by formulas (1) to (3) above. There are no particular limitations on the substituents that the constituent unit (D) may have, and for example, groups selected from substituent Z described later can be mentioned. Furthermore, it is preferable that the constituent unit (D) has at least one polar functional group (a) as a substituent, in that it can improve the adhesion of solid particles while also satisfying the relationships represented by the above formulas and showing an effect of improving cycle characteristics. In this invention, a constituent unit (D) having at least one polar functional group (a) is sometimes referred to as constituent unit (Da), and when simply referred to as constituent unit (D), it means both a constituent unit without the polar functional group (a) and the constituent unit (Da).

[0080] The polar functional group (a) of the constituent unit (Da) is the same as the polar functional group (a) of the polymer of the present invention, and the preferred ones are also the same. In the constituent unit (Da), the polar functional group (a) may be present on any of the constituent units, but in the polymer of the present invention incorporating the constituent unit (D), it is preferable that it be located in a position corresponding to the interior or end of the molecular chain that becomes the side chain, and more preferably at the end. The polar functional group (a) of the constituent unit (D) may be at least one type, and usually preferably one to three types. The compound that leads to the constituent unit (D) is not particularly limited, and examples include the polycondensable compound that leads to the constituent unit (D) that does not have the polar functional group (a), and is the same as the polycondensable compound that leads to the constituent unit (D) that does not have the polar functional group (a), and the preferred ones are also the same. For example, the polycondensable group, the polar functional group (a) or the terminal substituent having the polar functional group (a), and the linking group L which appropriately links the polycondensable group and the terminal substituent. Ａ２Examples of compounds having the above bond include, for example, methacrylic acid ester compounds having a polar functional group attached to a terminal substituent, (meth)acrylamide compounds having a polar functional group attached to a substituent that substitutes the nitrogen atom of an amide bond, styrene compounds having a polar functional group attached to a carbon atom of a benzene ring, and maleimide compounds having a polar functional group attached to a substituent that substitutes the nitrogen atom of an imide bond. Furthermore, the group represented by the above bond among the polar functional group (a) forms a cyclic unsaturated compound together with the polycondensable group, and this cyclic unsaturated compound itself becomes a compound that gives rise to the constituent unit (Da). For example, maleimide compounds are cyclic unsaturated compounds consisting of a polycondensable group and an imide group as the polar functional group (a), and this compound itself becomes a compound that gives rise to the constituent unit (Da). Examples of compounds that give rise to the constituent unit (Da) include the compounds used in the examples, but the present invention is not limited to these compounds.

[0081] - Constituent Unit (A) - In addition to the above constituent unit (D), the polymer of the present invention may include a constituent unit (A) having the above polar functional group (a), which does not satisfy at least one of the relationships represented by formulas (1) to (3). The relationship that constituent unit (A) does not satisfy only needs to be at least one of the relationships represented by formulas (1) to (3), and may be two or three. Constituent unit (A) usually does not satisfy the relationship represented by formula (1) or formula (3). In the case where the relationship represented by formula (1) or formula (2) is not satisfied in constituent unit (A), the energy level (eV) of HOMO and the value of the maximum positive charge on the carbon atom are not particularly limited as long as they are outside the ranges defined by each of the above formulas. Furthermore, in the case where the relationship defined by formula (3) is not satisfied, the relationship between the energy level of HOMO and the maximum positive charge on the carbon atom is not particularly limited.

[0082] The polar functional group (a) of the constituent unit (A) is the same as the polar functional group of the polymer of the present invention, and the preferred ones are also the same. In the constituent unit (A), the polar functional group (a) is preferably contained in the molecular chain that forms the side chain of the polymer of the present invention, and more preferably incorporated, for example, inside or at the end of the molecular chain that forms the side chain of the polymer of the present invention.

[0083] The constituent unit (A) only needs to have at least one polar functional group (a), and it is generally preferable that it has one to three polar functional groups. This constituent unit (A) only needs to have a polar functional group (a), and examples include constituent units derived from polycondensable compounds having at least one polar functional group from the functional group group (a). Examples of polycondensable compounds include compounds having a polycondensable group, a polar functional group (a) or a terminal substituent having a polar functional group (a), and a polymerizable group and a linking group that appropriately links the terminal substituent, and further, the polymerizable cyclic dicarboxylic acid anhydride described above. More specifically, such polycondensable compounds include compounds in which a carbon-carbon unsaturated bond as a polymerizable group and a polar functional group (a) are directly bonded, compounds in which a carbon-carbon unsaturated bond and a polar functional group (a) are bonded via a linking group, and further, compounds in which the polar functional group (a) itself contains a carbon-carbon unsaturated bond (for example, the polymerizable cyclic dicarboxylic acid anhydride described above). Furthermore, compounds having a polar functional group (a) include compounds that can introduce a polar functional group (a) into polymer structural units after polymerization through various reactions (for example, alcohol, amino, mercapto, or epoxy compounds (including polymers) that can undergo addition or condensation reactions with structural units derived from carboxylic anhydrides, structural units having carbon-carbon unsaturated bonds, etc.). The polycondensable group can be any group copolymerizable with the above structural unit (D), and is synonymous with the polycondensable group in the above structural unit (D), and the preferred group is also the same. The terminal substituent into which the polar functional group is introduced is not particularly limited, and is synonymous with the terminal substituent in the above structural unit (D), and the preferred group is also the same.

[0084] The linking group is not particularly limited, but for example, the linking group L in the above-described constituent unit (D) Ａ２ This is synonymous, but a group containing a -CO-O- group is preferred, and a -CO-O- group and a -CO-O-alkylene- group are preferred. The number of carbon atoms in the alkylene group contained in the linking group is as described above, but it is more preferably 1 to 6, and even more preferably 1 to 3. Note that the terminal substituent to which the polar functional group (a) is introduced is the linking group L. Ａ２ In cases where this can also be considered, this terminal substituent is a linking group LＡ２ Instead, it should be interpreted as a terminal substituent into which a polar functional group (a) is introduced.

[0085] The polycondensable compounds that derive the constituent unit (A) include, specifically, the following groups of compounds: (meth)acrylic compounds such as acrylic acid compounds, acrylic acid ester compounds, and (meth)acrylonitrile compounds; vinyl aromatic compounds such as vinylnaphthalene compounds and vinylcarbazole compounds, allyl compounds, vinyl ester compounds, vinyl ether compounds, cyclic olefin compounds, diene compounds, vinyl carboxylate compounds, and other vinyl compounds; dialkyl itaconic acid monomers; and vinyl succimide compounds.

[0086] Among these, acrylic acid ester compounds are preferred because they do not satisfy at least one of the relationships represented by formulas (1) to (3) above.

[0087] Examples of acrylic acid ester compounds include alkyl acrylate compounds and aryl acrylate compounds, with alkyl acrylate compounds being preferred and alkyl acrylate compounds being more preferred. The alkyl group constituting the alkyl acrylate compound may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, with linear or branched alkyl groups being preferred. The number of carbon atoms in the alkyl group constituting the alkyl acrylate compound is not particularly limited and can be, for example, 1 to 24, but is preferably determined considering the insufficiency of the relationships represented by the above formulas, the solubility of the polymer of the present invention in the dispersion medium, and the adhesion to solid particles. Focusing on the insufficiency of the relationships represented by the above formulas and solubility, a long-chain alkyl group is preferred as the alkyl group, and the number of carbon atoms of the long-chain alkyl group is preferably 4 to 24, more preferably 6 to 20, and even more preferably 8 to 14. On the other hand, focusing on the insufficiency of the relationships represented by the above formulas and adhesion, a short-chain alkyl group is preferred as the alkyl group, and the number of carbon atoms of the short-chain alkyl group is preferably 1 to 3. When the alkyl group is a cyclic alkyl group, the lower limit of the number of carbon atoms is preferably 6. The number of carbon atoms in the aryl group constituting the aryl ester is not particularly limited, but can be, for example, 6 to 24, preferably 6 to 10, and more preferably 6.

[0088] The constituent unit (A) may have substituents other than the polar functional group (a), as long as it does not satisfy the relationships represented by formulas (1) to (3) above. The substituents that the constituent unit (A) may have are not particularly limited, and examples include groups selected from substituent Z described later (excluding the polar functional group (a)).

[0089] - Other constituent units - In addition to the above constituent units (D) and (A), the polymer of the present invention may have other constituent units. Other constituent units are those that do not fall under either of the above constituent units (D) or (A), and include constituent units that do not satisfy at least one of the relationships represented by formulas (1) to (3) and do not have the above polar functional group (a). The relationships that the other constituent units do not satisfy may be at least one of the relationships represented by formulas (1) to (3), and may be two or three. Other constituent units often do not satisfy the relationship represented by formula (1) or formula (3). In the case of other constituent units that do not satisfy the relationship represented by formula (1) or formula (2), the energy level (eV) of HOMO and the value of the maximum positive charge on the carbon atom are not particularly limited as long as they are outside the ranges specified by each of the above formulas. Also, in the case that the relationship specified by formula (3) is not satisfied, the relationship between the energy level of HOMO and the maximum positive charge on the carbon atom is not particularly limited.

[0090] Other constituent units include, for example, constituent units derived from polycondensable compounds having ethylenically unsaturated groups and no polar functional groups (preferably low molecular weight). More specifically, these include constituent units derived from the (meth)acrylic acid compound (M1) mentioned above, constituent units derived from vinyl compounds (M2), and constituent units derived from halogenated vinyl compounds such as difluoroethylene and hexafluoropropylene. Constituent units derived from styrene compounds, (meth)acrylic acid ester compounds, and (meth)acrylonitrile compounds are preferred, as are constituent units derived from unsubstituted alkyl ester compounds of (meth)acrylic acid and alkyl ester compounds of (meth)acrylic acid with aryl groups. Among other constituent units, those derived from acrylic acid ester compounds of long-chain unsubstituted alkyl groups are one of the more preferred embodiments in terms of the solubility of the polymer binder in the dispersion medium. Among other constituent units, those derived from acrylic acid ester compounds of short-chain unsubstituted alkyl groups and those derived from acrylic acid ester compounds of short-chain alkyl groups substituted with aryl groups are also among the more preferred embodiments. The number of carbon atoms in the long-chain alkyl group and the short-chain alkyl group are as described above.

[0091] The polymer of the present invention may have one or more of the above-mentioned constituent units. Preferably, the polymer of the present invention is a single polymer or copolymer containing one or two of the above-mentioned constituent units (D). The combination of two or more constituent units (D) is not particularly limited, and appropriate constituent units (D) can be combined. For example, combinations of two or more constituent units that do not have a polar functional group (a), combinations of a constituent unit (Da) having a polar functional group (a) and a constituent unit (D) that does not have a polar functional group (a), and combinations of constituent units (Da) having a polar functional group (a) can be mentioned. Specifically, when a constituent unit (Da) having an amide group or an imide group as the polar functional group (a) is included, it is preferable to have a polymer consisting of one or more of these constituent units (Da), or a polymer consisting of these constituent units (Da) and constituent units (D) that do not have a polar functional group (a). On the other hand, if the polymer includes a constituent unit (Da) having a polar functional group other than an amide group or imide group as the polar functional group (a), it is preferable that the polymer includes the constituent unit (D) and a constituent unit (D) that does not have the polar functional group (a).

[0092] In the polymer of the present invention, when a constituent unit (A) is included, the combination of constituent unit (D) and constituent unit (A) is not particularly limited, and examples include combinations of appropriate constituent unit (D) and appropriate constituent unit (A), with a preferred combination of a preferred constituent unit (D) and a preferred constituent unit (A). Specific examples of the polymer of the present invention include the polymer synthesized in the examples described later, but the present invention is not limited to these.

[0093] The polymer of the present invention can be a commercially available product or a synthetic product. The polymer of the present invention can be synthesized by homopolymerization or copolymerization of raw material compounds (monomers) by known methods. Specifically, it can be synthesized by the method described in the examples below. There are no particular limitations on the method of incorporating the polar functional group (a), and examples include copolymerization of a polycondensable compound having the polar functional group (a), using a polymerization initiator or chain transfer agent having (or producing) the polar functional group (a), utilizing polymer reactions, ene reactions to double bonds, ene-thiol reactions, or ATRP (Atom Transfer Radical Polymerization) polymerization using a copper catalyst. In addition, the polar functional group (a) can also be introduced by using functional groups present in the main chain, side chains, or terminals of the polymer of the present invention as reaction sites. For example, the polar functional group (a) can be introduced by using a compound having a functional group and various reactions with dicarboxylic acid anhydride groups in the polymer chain.

[0094] The polymer, constituent unit (D), constituent unit (A), and other constituent units of the present invention may have substituents (excluding the polar functional group (a) above). The substituents that the polymer and each constituent unit of the present invention may have are not particularly limited, but include groups selected from the substituent Z below (excluding the polar functional group (a) above).

[0095] - Substituent Z - Alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, e.g., methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl group (preferably an alkenyl group having 2 to 20 carbon atoms, e.g., vinyl, allyl, oleyl, etc.), alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, e.g., ethynyl, butadiinyl, phenylethynyl, etc.), cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, e.g., cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.) In this invention, the term alkyl group usually includes cycloalkyl groups, but this is described separately here.), aryl groups (preferably aryl groups having 6 to 26 carbon atoms, e.g., phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl groups (preferably aralkyl groups having 7 to 23 carbon atoms, e.g., benzyl, phenethyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, more preferably heterocyclic groups of 5 or 6 members having at least one oxygen atom, a sulfur atom, or a nitrogen atom. Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups.For example, tetrahydropyran ring group, tetrahydrofuran ring group, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, pyrrolidone group, etc.), alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms, for example, phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy group (a group in which an -O- group is bonded to the above heterocyclic group), alkoxycarbonyl group (preferably Or, alkoxycarbonyl groups having 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, etc.), aryloxycarbonyl groups (preferably aryloxycarbonyl groups having 7 to 26 carbon atoms, for example, phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), heterocyclic oxycarbonyl groups (groups in which an -O-CO- group is bonded to the above heterocyclic group), amino groups (preferably amino groups having 0 to 20 carbon atoms, alkylamino groups, arylamino groups, for example, amino(-NH). ２), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl group (preferably a sulfamoyl group having 0 to 20 carbon atoms, for example, N,N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyl group (including alkylcarbonyl group, alkenylcarbonyl group, alkynylcarbonyl group, arylcarbonyl group, heterocyclic carbonyl group, preferably an acyl group having 1 to 20 carbon atoms, for example, acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotinoyl, etc.), acyl Oxy groups (including alkylcarbonyloxy groups, alkenylcarbonyloxy groups, alkynylcarbonyloxy groups, and heterocyclic carbonyloxy groups, preferably acyloxy groups having 1 to 20 carbon atoms, for example, acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyloxy, acryloyloxy, methacryloyloxy, crotonoyloxy, nicotinoyloxy, etc.), allyloxy groups (preferably allyloxy groups having 7 to 23 carbon atoms, for example, benzoyloxy, naphthoyloxy, etc.), carbamoyl groups (preferably carbamoyl groups having 1 to 20 carbon atoms, for example, N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), acylamino group (preferably an acylamino group having 1 to 20 carbon atoms, e.g., acetylamino, benzoylamino, etc.), alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms, e.g., methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio group (preferably an arylthio group having 6 to 26 carbon atoms, e.g., phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), heterocyclic thio group (a group in which an -S- group is bonded to the above heterocyclic group), alkylsulfonyl group (preferably an alkylsulfonyl group having 1 to 20 carbon atoms, e.g., methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl group (preferably carbon Arylsulfonyl groups with 6 to 22 carbon atoms, for example, benzenesulfonyl), alkylsilyl groups (preferably alkylsilyl groups with 1 to 20 carbon atoms, for example, monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl), arylsilyl groups (preferably arylsilyl groups with 6 to 42 carbon atoms, for example, triphenylsilyl), alkoxysilyl groups (preferably alkoxysilyl groups with 1 to 20 carbon atoms, for example, monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl), aryloxysilyl groups (preferably aryloxysilyl groups with 6 to 42 carbon atoms, for example, triphenyloxysilyl), phosphoryl groups (preferably phosphate groups with 0 to 20 carbon atoms, for example, -OP(=O)(R, Ｐ ) ２ ), phosphonyl group (preferably a phosphonyl group having 0 to 20 carbon atoms, for example, -P(=O)(R Ｐ ) ２ ), phosphenyl group (preferably a phosphenyl group having 0 to 20 carbon atoms, for example, -P(R Ｐ ) ２ ), phosphonic acid group (preferably a phosphonic acid group having 0 to 20 carbon atoms, for example, -PO(OR Ｐ ) ２ Examples include sulfo groups (sulfonic acid groups), carboxyl groups, hydroxyl groups, sulfanyl groups, cyano groups, and halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.). Ｐis a hydrogen atom or a substituent (preferably a group selected from substituent Z). Furthermore, each of the groups listed as substituent Z may be further substituted with substituent Z. The alkyl group, alkylene group, alkenyl group, alkenylene group, alkynyl group and / or alkynylene group, etc. may be cyclic or linear, and may be linear or branched.

[0096] The content of each constituent unit in the polymer of the present invention is not particularly limited and can be determined as appropriate, for example, within the following range. The content of each constituent unit in the polymer of the present invention is set within the following range, for example, such that the total content of all constituent units is 100% by mass. If two or more constituent units corresponding to a specific constituent unit are included, the total content of these constituent units is used.

[0097] The polymer of the present invention has a total content of constituent unit (D) (including the content of constituent unit (Da)) of 80% by mass or more. When the total content of constituent unit (D) in the polymer of the present invention is 80% by mass or more, the inorganic solid electrolyte-containing composition of the present invention exhibits excellent dispersion stability and handling properties, and solid particles can be firmly adhered to it, resulting in the realization of an all-solid-state secondary battery with low resistance and excellent high-potential cycle characteristics. The total content of constituent unit (D) in the polymer of the present invention is preferably 90% by mass or more, and more preferably 95% by mass or more, in terms of dispersion stability, handling properties, adhesion of solid particles, and furthermore, resistance and high-potential cycle characteristics. On the other hand, the upper limit of the total content of constituent unit (D) in the polymer of the present invention can be 100% by mass. When the polymer of the present invention contains constituent unit (A) and / or other constituent units, the upper limit of the total content of constituent unit (D) is preferably, for example, 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less.

[0098] In the present invention, the content of constituent units (D) without polar functional groups (a) in the polymer of the present invention is appropriately determined considering the above total content, and is preferably 0 to 100% by mass, more preferably 0 to 80% by mass, even more preferably 0 to 70% by mass, and particularly preferably 0 to 50% by mass, in terms of maintaining dispersion stability, handling properties, resistance, and high potential cycle characteristics while exhibiting appropriate adhesion to solid particles. Furthermore, the content of constituent units (D) without polar functional groups (a) in the constituent units (D) is not particularly limited and can be appropriately determined. For example, when the total mass of constituent units (D) is 100% by mass, the content of constituent units (D) without polar functional groups (a) is preferably 0 to 100% by mass, more preferably 0 to 80% by mass, even more preferably 0 to 50% by mass, and particularly preferably 0 to 30% by mass, in terms of dispersion stability, handling properties, adhesion to solid particles, resistance, and high potential cycle characteristics.

[0099] In the present invention, the content of constituent units (Da) having polar functional groups (a) in the polymer of the present invention is appropriately determined considering the above total content, and is preferably 0 to 100% by mass, more preferably 30 to 100% by mass, and even more preferably 50 to 100% by mass, in terms of maintaining dispersion stability, handling properties, adhesion to solid particles, and resistance while further improving high-potential cycle characteristics. Furthermore, the content of constituent units (Da) in constituent units (D) is not particularly limited and can be appropriately determined. For example, when the total mass of constituent units (D) is 100% by mass, the content of constituent units (Da) is preferably 10 to 100% by mass, more preferably 20 to 100% by mass, even more preferably 30 to 100% by mass, and particularly preferably 50 to 100% by mass, in terms of dispersion stability, handling properties, adhesion to solid particles, resistance, and high-potential cycle characteristics. In the present invention, as described above, the amide group and imide group among the polar functional groups (a) tend to form polycondensable compounds that satisfy the relationships represented by formulas (1) to (3) above. Therefore, one preferred embodiment is to set the content of constituent units (Da) having an amide group and / or an imide group as the polar functional group (a) to the same range as the total content of constituent units (D). On the other hand, the content of constituent units (Da) having polar functional groups other than the amide group and imide group among the polar functional groups (a) is preferably set to a relatively low level in order to exhibit appropriate adhesion to solid particles, for example, preferably 1 to 50% by mass, more preferably 3 to 30% by mass, and even more preferably 5 to 20% by mass.

[0100] The content of constituent unit (A) in the polymer of the present invention can be appropriately determined considering the content of constituent unit (Da), etc. For example, if the polymer of the present invention contains constituent unit (Da), the content of constituent unit (A) in the polymer of the present invention may be 0% by mass. For example, it is preferable that the content be 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass, in order to further improve dispersion stability, handling, adhesion of solid particles, and resistance while maintaining excellent high-potential cycle characteristics. On the other hand, if the polymer of the present invention does not contain constituent unit (Da), the content of constituent unit (A) in the polymer of the present invention is set to a content greater than 0% by mass in terms of adhesion of solid particles. In this case, the content of constituent unit (A) is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and even more preferably 3 to 10% by mass, in order to further improve dispersion stability, handling, adhesion of solid particles, and resistance while maintaining excellent high-potential cycle characteristics.

[0101] In the present invention, the mass ratio of the total content of constituent unit (D) to the content of constituent unit (A) [(total content of constituent unit (D)) / (content of constituent unit (A))] can be determined as appropriate. For example, the mass ratio [(total content of constituent unit (D)) / (content of constituent unit (A)] is preferably 4 to 99, more preferably 5 to 50, and even more preferably 9 to 20, in terms of dispersion stability, handling properties, adhesion of solid particles, and further resistance and high-potential cycle characteristics.

[0102] The total content of other constituent units in the polymer of the present invention is not particularly limited, but is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass. When the polymer of the present invention contains constituent unit (A) and other constituent units, the total content of constituent unit (A) and other constituent units in the polymer of the present invention can be appropriately determined considering the total content of the above-mentioned constituent unit (D). The above total content is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, in terms of not impairing dispersion stability, handling properties, solid particle adhesion, resistance, and high-potential cycle characteristics.

[0103] The polymer of the present invention may be a stepwise polymer (polycondensation, polyaddition, or addition-condensation) as long as it has the above-mentioned polar functional group (a) and the above-mentioned structural unit (D), but it is preferable that the polymer has a polymerization chain of carbon-carbon double bonds as its main chain. In the present invention, a polymerization chain of carbon-carbon double bonds refers to a polymerization chain formed by the polymerization of carbon-carbon double bonds (ethylenically unsaturated groups), and specifically refers to a polymerization chain obtained by polymerizing (homopolymerization or copolymerization) monomers having carbon-carbon unsaturated bonds. Examples of polymers having a polymerization chain of carbon-carbon double bonds as its main chain include chain polymerization polymers such as fluoropolymers (fluorine-containing polymers), hydrocarbon polymers, vinyl polymers, and (meth)acrylic polymers. The polymer of the present invention is preferably a vinyl polymer or a (meth)acrylic polymer, and more preferably a (meth)acrylic polymer. As the (meth)acrylic polymer, polymers of (meth)acrylic acid ester compounds ((meth)acrylic acid ester polymers) are preferred, but among (meth)acrylic polymers, polymers containing 50% by mass or more of constituent units derived from methacrylic acid ester compounds, polymers containing at least one of constituent units derived from (meth)acrylamide compounds and polymers containing constituent units derived from maleimide compounds are preferred. A polymer containing 50% by mass or more of constituent units derived from methacrylic acid ester compounds may contain less than 50% by mass of constituent units derived from acrylic acid ester compounds, but does not contain constituent units derived from (meth)acrylamide compounds or polymers containing at least one of constituent units derived from maleimide compounds. On the other hand, a polymer containing at least one of constituent units derived from (meth)acrylamide compounds and polymers containing at least one of constituent units derived from maleimide compounds may further contain constituent units derived from (meth)acrylic acid ester compounds, and copolymers of (meth)acrylamide compounds and maleimide compounds, polymers consisting only of (meth)acrylamide compounds ((meth)acrylamide polymers), polymers consisting only of maleimide compounds (maleimide polymers), etc., are more preferred.

[0104] The content of each constituent unit in a polymer containing at least one of constituent units derived from a (meth)acrylamide compound and a maleimide compound is not particularly limited. For example, in a polymer containing constituent units derived from a (meth)acrylamide compound and constituent units derived from a maleimide compound, the content of constituent units derived from the (meth)acrylamide compound in the polymer can be 0 to 100% by mass, and is preferably 10 to 500% by mass. In a polymer containing constituent units derived from an acrylamide compound or a maleimide compound and constituent units derived from a (meth)acrylic acid ester compound, the content of constituent units derived from the (meth)acrylic acid ester compound in the polymer can be 1 to 80% by mass, and is preferably 50 to 80% by mass.

[0105] The polymer of the present invention is not particularly limited in its molecular structure as long as it has the above-mentioned constituent unit (D), and can take various molecular structures such as linear polymers (straight-chain polymers), graft polymers, dendrimers, star-shaped polymers, and core-shell polymers. The polymer of the present invention is preferably not a highly branched polymer such as a dendrimer or star-shaped polymer, or not a core-shell polymer. Specifically, linear polymers or graft polymers are preferred, and linear polymers are more preferred. In the present invention, linear polymers include not only polymers that do not have a completely branched structure, but also substantially straight-chain polymers that have short molecular chains (non-polymerizable molecular structures) in addition to the main chain. Graft polymers refer to polymers that have polymerizable graft chains as side chains. When the polymer of the present invention contains multiple types of constituent units, the polymer of the present invention may be a block polymer, an alternating polymer, etc., but it is preferably a random polymer.

[0106] (Physical properties or characteristics of the polymer or polymer binder of the present invention) The polymer binder (polymer of the present invention) exhibits the property of dissolving in the dispersion medium contained in the inorganic solid electrolyte-containing composition (solubility). That is, the polymer binder in the inorganic solid electrolyte-containing composition exists in a dissolved state in the dispersion medium, depending on its content. When the polymer binder is dissolved in the dispersion medium, it can stably exhibit the function of dispersing solid particles in the dispersion medium, thereby improving the dispersion state of solid particles in the inorganic solid electrolyte-containing composition. In the present invention, the state in which the polymer binder is dissolved in the dispersion medium is not limited to the state in which all of the polymer binder is dissolved in the dispersion medium. For example, if the solubility in the dispersion medium is 50% or more, a portion of the polymer binder may exist insoluble in the inorganic solid electrolyte-containing composition. If the polymer binder contains components other than the polymer of the present invention, it is sufficient that at least the polymer of the present invention satisfies the above solubility requirement. The method for measuring solubility is as follows. Specifically, approximately 0.1 g of the binder component (solid) was accurately weighed, and this weighed mass was defined as W0. Next, the binder component and 10 g of the dispersion medium were placed in a container and mixed using a mix rotor (model VMR-5, manufactured by AS ONE Corporation) at 25°C and 100 rpm for 48 hours. After that, insoluble matter was filtered from the solution, and the resulting solid was vacuum-dried at 120°C for 3 hours, and the mass W1 of the insoluble matter was accurately weighed. Then, the solubility (%) in the dispersion medium was calculated according to the following formula: Solubility (%) = (W0 - W1) / W0 × 100

[0107] In the present invention, the solubility of the polymer binder in the dispersion medium can be appropriately imparted depending on the structure and composition (types and content of constituent units) of the polymer of the present invention, as well as the combination with the dispersion medium.

[0108] The weight-average molecular weight of the polymer of the present invention is not particularly limited. For example, 0.5 × 10 ３ The above is preferable, 20 x 10 ３ The above is more preferable, 50 x 10 ３ The above is even more preferable, 100 x 10 ３The above is particularly preferable. The upper limit is 5 x 10 ６ The following is the actual result, but 2 x 10 ６ The following is preferable: 8.0 × 10 ５ The following is more preferable: 5.0 × 10 ５ The following is even more preferable. The weight-average molecular weight of the polymer of the present invention can be appropriately adjusted by changing the type and content of the polymerization initiator, polymerization time, polymerization temperature, etc.

[0109] - Measurement of Molecular Weight - In this invention, unless otherwise specified, the molecular weight of polymers and polymer chains refers to the weight-average molecular weight or number-average molecular weight on a standard polystyrene basis, measured by gel permeation chromatography (GPC). The basic measurement method is the method set in either condition 1 or condition 2 below, but condition 2 is given priority. However, depending on the type of polymer and polymer chain, an appropriate eluent may be selected and used as appropriate. (Condition 1) Column: Two TOSOH TSKgel Super AWM-H (product name, manufactured by Tosoh Corporation) connected together. Carrier: 10 mM LiBr / N-methylpyrrolidone. Measurement temperature: 40°C. Carrier flow rate: 1.0 ml / min. Sample concentration: 0.1% by mass. Detector: RI (refractive index) detector. (Condition 2) Column: A column made by connecting TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, or TOSOH TSKgel Super HZ2000 (all product names, manufactured by Tosoh Corporation). Carrier: Tetrahydrofuran. Measurement temperature: 40°C. Carrier flow rate: 1.0 ml / min. Sample concentration: 0.1% by mass. Detector: RI (refractive index) detector.

[0110] The polymer of the present invention is preferably 0.20 mmol / g or less in terms of suppressing excessive adsorption to solid particles. The acid value of the polymer of the present invention is preferably 0.10 mmol / g or less, and more preferably 0.05 mmol / g or less, in terms of maintaining high potential cycle characteristics while exhibiting appropriate adhesion to solid particles, thereby improving dispersion stability, handling properties, and resistance. The lower limit of the acid value of the polymer of the invention is not particularly limited and can be 0 mmol / g. The acid value of the polymer of the present invention was calculated as follows: 0.5 g of polymer solids was dissolved in 20 mL of toluene and 20 mL of tetrahydrofuran, and titrated with a 0.1 N potassium hydroxide ethanol solution using a potentiometric automatic titrator AT-510 (manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The acid value was calculated from the peak in the pH range of 2.0 to 9.0. The type of solvent and titration reagent (base) can be appropriately selected according to the solubility of the polymer.

[0111] The polymer of the present invention may be a non-crosslinked polymer or a crosslinked polymer. Furthermore, if crosslinking of the polymer of the present invention progresses due to heating or the application of voltage, the molecular weight may be greater than the molecular weight described above. Preferably, the polymer of the present invention has a weight-average molecular weight within the above range when the all-solid-state secondary battery is first put into use.

[0112] The polymer of the present invention is preferably amorphous. In the present invention, "amorphous" typically means that when the glass transition temperature is measured, no endothermic peak due to crystal melting is observed. The water content of the polymer binder (polymer of the present invention) is preferably 100 ppm (by mass) or less. The polymer binder (polymer of the present invention) may be crystallized and dried, or the dispersion may be used as is.

[0113] <Other Polymers> The polymer binder may contain one or more other polymers to reinforce the function of the polymer of the present invention as described above. Such other polymers can be appropriately selected and used if they function as binders commonly used in all-solid-state secondary batteries. The content of the other polymers in the polymer binder is not particularly limited, but is preferably 0.01 to 4% by mass of 100% by mass of the polymer binder.

[0114] The content of the polymer binder in the inorganic solid electrolyte-containing composition is not particularly limited, but is preferably 0.1 to 5.0% by mass, more preferably 0.2 to 4.0% by mass, and even more preferably 0.3 to 2.0% by mass, in terms of dispersion stability, handling properties, adhesion of solid particles, and furthermore, resistance and high-potential cycle characteristics. Similarly, the content of the polymer binder in 100% by mass of the solid content of the inorganic solid electrolyte-containing composition (equivalent to solid content) is preferably 0.1 to 6.0% by mass, more preferably 0.3 to 5.0% by mass, and even more preferably 0.4 to 2.5% by mass, for the same reasons. In the present invention, in 100% by mass of solid content, the mass ratio of the total mass of the inorganic solid electrolyte and active material (total amount) to the mass of the polymer binder [(mass of inorganic solid electrolyte + mass of active material) / (total mass of polymer binder)] is preferably in the range of 1000 to 1. This ratio is more preferably 500 to 2, and even more preferably 100 to 10.

[0115] [Dispersion Medium] The inorganic solid electrolyte-containing composition of the present invention contains a dispersion medium that disperses or dissolves each of the above components. Such a dispersion medium can be any organic compound that is liquid in the environment of use, for example, various organic solvents, specifically alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, nitrile compounds, ester compounds, etc. The dispersion medium can be either a nonpolar dispersion medium (hydrophobic dispersion medium) or a polar dispersion medium (hydrophilic dispersion medium), but a nonpolar dispersion medium is preferred in that it can exhibit excellent dispersibility. A nonpolar dispersion medium generally refers to a substance with low affinity for water, and in the present invention, for example, ester compounds, ketone compounds, ether compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, etc.

[0116] Examples of alcohol compounds include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, 2-methyl-2,4-pentanediol, 1,3-butanediol, and 1,4-butanediol.

[0117] Examples of ether compounds include alkylene glycols (diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, etc.), alkylene glycol monoalkyl ethers (ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, etc.), alkylene glycol dialkyl ethers (ethylene glycol dimethyl ether, etc.), dialkyl ethers (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), and cyclic ethers (tetrahydrofuran, dioxane (including the 1,2-, 1,3-, and 1,4- isomers), etc.).

[0118] Examples of amide compounds include N,N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropanamide, and hexamethylphosphoric triamide.

[0119] Examples of amine compounds include triethylamine, diisopropylethylamine, and tributylamine. Examples of ketone compounds include acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone, cyclohexanone, cycloheptanone, dipropyl ketone, dibutyl ketone, diisopropyl ketone, diisobutyl ketone (DIBK), isobutylpropyl ketone, sec-butylpropyl ketone, pentylpropyl ketone, and butylpropyl ketone. Examples of aromatic hydrocarbon compounds include benzene, toluene, xylene, mesitylene, and perfluorotoluene. Examples of aliphatic hydrocarbon compounds include hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane, decalin, paraffin, gasoline, naphtha, kerosene, and diesel fuel. Examples of nitrile compounds include acetonitrile, propionitrile, and isobutyronitrile. Examples of ester compounds include ethyl acetate, propyl acetate, butyl acetate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, butyl pentanoate, pentyl pentanoate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, isobutyl isobutyrate, propyl pivalate, isopropyl pivalate, butyl pivalate, and isobutyl pivalate.

[0120] In the present invention, ether compounds, ketone compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, and ester compounds are preferred, and ester compounds, ketone compounds, aromatic hydrocarbon compounds, or ether compounds are more preferred.

[0121] The number of carbon atoms in the compounds constituting the dispersion medium is not particularly limited, but is preferably 2 to 30, more preferably 4 to 20, even more preferably 6 to 15, and particularly preferably 7 to 12.

[0122] The boiling point of the dispersion medium at normal pressure (1 atmosphere: 101325 Pa) is not particularly limited, but is preferably 50°C or higher, and more preferably 70°C or higher. The upper limit is preferably 250°C or lower, and even more preferably 220°C or lower.

[0123] The inorganic solid electrolyte-containing composition may contain one or more dispersion media. Examples of compositions containing two or more dispersion media include xylene (a mixture of xylene isomers with a mixed molar ratio of ortho-isomer:para-isomer:meta-isomer = 1:5:2), and mixed xylene (a mixture of o-xylene, p-xylene, m-xylene, and ethylbenzene). The content of the dispersion media in the inorganic solid electrolyte-containing composition is not particularly limited and is set within a range that satisfies the above-mentioned solid content concentration.

[0124] [Active Material] One preferred embodiment of the inorganic solid electrolyte-containing composition of the present invention is that it contains an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the periodic table. Examples of the active material include positive electrode active material and negative electrode active material, which will be described below. In the present invention, the inorganic solid electrolyte-containing composition containing the 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).

[0125] <Positive Electrode Active Material> The positive electrode active material is an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the periodic table, and is preferably capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above characteristics, and may be a transition metal oxide, or an organic substance, sulfur, or other element that can be compounded with Li. Among these, it is preferable to use a transition metal oxide as the positive electrode active material, and a transition metal element M ａ A transition metal oxide having one or more elements selected from Co, Ni, Fe, Mn, Cu, and V is more preferable. ｂ Other elements of the periodic table of metals, such as elements from Group 1 (Ia), Group 2 (IIa), Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B, may be mixed. The amount of the transition metal element M may be used. ａ Li / M ａ A more preferable product is one synthesized by mixing the elements so that the molar ratio is 0.3 to 2.2. Specific examples of transition metal oxides include (MA) transition metal oxides having a layered rock salt structure, (MB) transition metal oxides having a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD) lithium-containing transition metal halogenated phosphate compounds, and (ME) lithium-containing transition metal silicate compounds.

[0126] (MA) As a specific example of a transition metal oxide having a layered rock salt structure, LiCoO ２ (Lithium cobalt oxide [LCO]), LiNi ２ O ２ (Lithium nickelate), LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ (Lithium nickel-cobalt aluminate [NCA]), LiNi １／３ Co １／３ Mn １／３ O ２ (Lithium nickel manganese cobalt oxide [NMC]) and LiNi ０．５ Mn ０．５ O ２(Lithium manganese nickelate) is one example. (MB) LiMn is a specific example of a transition metal oxide having a spinel-type structure. ２ O ４ (LMO), LiCoMnO ４ Li ２ FeMn ３ O ８ Li ２ CuMn ３ O ８ Li ２ CrMn ３ O ８ and Li ２ NiMn ３ O ８ Examples include (MC) lithium-containing transition metal phosphate compounds, such as LiFePO ４ and Li ３ Fe ２ (PO ４ ) ３ Olivine-type iron phosphates such as LiFeP ２ O ７ Iron pyrophosphates such as LiCoPO ４ Cobalt phosphates such as Li ３ V ２ (PO ４ ) ３ Examples include monoclinic vanadium phosphate salts such as (lithium vanadium phosphate). Examples of (MD) lithium-containing transition metal halide phosphate compounds include Li ２ FePO ４ F, etc., iron fluoride phosphate, Li ２ MnPO ４ F and other manganese phosphate fluorides and Li ２ CoPO ４ Examples include cobalt fluoride phosphates such as F. (ME) Examples of lithium-containing transition metal silicate compounds include Li ２ FeSiO ４ Li ２ MnSiO ４ Li ２ CoSiO ４ Examples include the above. In the present invention, transition metal oxides having a (MA) layered rock salt type structure are preferred, and LCO or NMC are more preferred.

[0127] The shape of the positive electrode active material is not particularly limited, but it is preferably particulate in the inorganic solid electrolyte-containing composition. When the positive electrode active material is particulate, the particle size (volume average particle size) of the positive electrode active material is not particularly limited. For example, it can be 0.1 to 50 μm. The particle size of the positive electrode active material particles can be prepared in the same manner as the particle size of the inorganic solid electrolyte, and the measurement method is also the same as the method for measuring the particle size of the inorganic solid electrolyte. The positive electrode active material obtained by the calcination method may be used after washing with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0128] The inorganic solid electrolyte-containing composition may contain one or more positive electrode active materials. The content of the positive electrode active material in the inorganic solid electrolyte-containing composition is not particularly limited, but is preferably 10 to 97% by mass, more preferably 30 to 95% by mass, even more preferably 40 to 93% by mass, and particularly preferably 50 to 90% by mass, based on 100% by mass of solid content.

[0129] <Negative Electrode Active Material> The negative electrode active material is an active material capable of inserting and releasing ions of metals belonging to Group 1 or Group 2 of the periodic table, and is preferably capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above characteristics, and examples include carbonaceous materials, metal oxides, metal composite oxides, elemental lithium, lithium alloys, and negative electrode active materials that can form alloys with lithium (can be alloyed). Among these, carbonaceous materials, metal composite oxides, or elemental lithium are preferred from the viewpoint of reliability. Active materials that can be alloyed with lithium are preferred in that they enable the production of high-capacity all-solid-state secondary batteries.

[0130] Carbonaceous materials used as negative electrode active materials are materials that consist substantially of carbon. Examples include petroleum pitch, carbon black such as acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor-grown graphite, etc.), and carbonaceous materials obtained by firing various synthetic resins such as PAN (polyacrylonitrile) resins or furfuryl alcohol resins. Furthermore, examples include various types of carbon fibers such as PAN-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polyvinyl alcohol)-based carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers, as well as mesophase microspheres, graphite whiskers, and plate-shaped graphite. These carbonaceous materials can also be divided into hard carbonaceous materials (also called hard carbon) and graphitic carbonaceous materials depending on the degree of graphitization. Furthermore, the carbonaceous material preferably has the interplanar spacing or density and crystallite size described in Japanese Patent Publication No. 62-22066, Japanese Patent Publication No. 2-6856, and Japanese Patent Publication No. 3-45473. The carbonaceous material does not need to be a single material; a mixture of natural graphite and artificial graphite described in Japanese Patent Publication No. 5-90844, graphite having a coating layer described in Japanese Patent Publication No. 6-4516, etc., can also be used. Hard carbon or graphite is preferably used as the carbonaceous material, and graphite is more preferably used.

[0131] The oxides of metals or metalloid elements used as negative electrode active materials are not particularly limited as long as they are oxides capable of intercalating and releasing lithium, and include metal oxides, composite oxides of metal elements or composite oxides of metal elements and metalloid elements (collectively referred to as metal composite oxides), and metalloid oxides. Among these oxides, amorphous oxides are preferred, and chalcogenides, which are reaction products of metal elements and elements of Group 16 of the periodic table, are also preferred. In the present invention, metalloid elements refer to elements that exhibit properties intermediate between metal elements and nonmetal elements, and usually include the six elements boron, silicon, germanium, arsenic, antimony, and tellurium, and further include the three elements selenium, polonium, and astatine. Furthermore, amorphous means having a broad scattering band with peaks in the region of 20° to 40° at 2θ values ​​in X-ray diffraction using CuKα rays, and may have crystalline diffraction lines. Preferably, the strongest intensity of the crystalline diffraction lines observed at 40° to 70° 2θ is 100 times or less, more preferably 5 times or less, the intensity of the diffraction line at the peak of the broad scattering band observed at 20° to 40° 2θ, and it is particularly preferable that there are no crystalline diffraction lines.

[0132] Among the group of compounds consisting of amorphous oxides and chalcogenides described above, amorphous oxides of metalloid elements or the chalcogenides described above are more preferred, and oxides (compounds) consisting of one element selected from groups 13 (IIIB) to 15 (VB) of the periodic table (for example, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) or a combination of two or more such elements, or chalcogenides are particularly preferred. Specific examples of preferred amorphous oxides and chalcogenides include, for example, Ga ２ O ３ , GeO, PbO, PbO ２ Pb ２ O ３ Pb ２ O ４ Pb ３ O ４ Sb ２ O ３ Sb ２ O ４ Sb ２ O ８Bi ２ O ３ Sb ２ O ８ Si ２ O ３ Sb ２ O ５ , Bi ２ O ３ , Bi ２ O ４ , GeS, PbS, PbS ２ Sb ２ S ３ or Sb ２ S ５ Preferably, the following can be used in combination with amorphous oxides mainly composed of Sn, Si, and Ge: carbonaceous materials capable of intercalating and / or releasing lithium ions or lithium metal, elemental lithium, lithium alloys, and negative electrode active materials that can be alloyed with lithium.

[0133] From the viewpoint of high current density charge-discharge characteristics, oxides of metals or metalloid elements, particularly metal (composite) oxides and the above chalcogenides, preferably contain at least one of titanium and lithium as constituent units. Examples of lithium-containing metal composite oxides (lithium composite metal oxides) include composite oxides of lithium oxide and the above metal (composite) oxide or the above chalcogenide, more specifically Li ２ SnO ２ Examples include: The negative electrode active material, for example, a metal oxide, is also preferably one that contains titanium (titanium oxide). Specifically, Li ４ Ti ５ O １２ Lithium titanate (LTO) is preferable because it exhibits excellent rapid charge-discharge characteristics due to its small volume fluctuation during lithium ion intercalation and deintercalation, which suppresses electrode degradation and improves the lifespan of lithium-ion secondary batteries.

[0134] The lithium alloy used as the negative electrode active material is not particularly limited as long as it is an alloy that is commonly used as the negative electrode active material for secondary batteries. For example, lithium aluminum alloy, specifically a lithium aluminum alloy in which lithium is the base metal and 10% by mass of aluminum is added, is an example.

[0135] The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is one that is commonly used as a negative electrode active material in secondary batteries. Such active materials expand and contract significantly due to charging and discharging of all-solid-state secondary batteries, accelerating the deterioration of cycle characteristics. However, the inorganic solid electrolyte-containing composition of the present invention contains the above-mentioned polymer binder, and therefore can suppress the deterioration of cycle characteristics (including high-potential cycle characteristics). Examples of such active materials include (negative electrode) active materials (alloys, etc.) having silicon or tin elements, and metals such as Al and In. Negative electrode active materials having silicon elements (silicon-containing active materials) that enable higher battery capacity are preferred, and silicon-containing active materials with a silicon content of 50 mol% or more of the total constituent elements are more preferred. Generally, negative electrodes containing these negative electrode active materials (for example, Si negative electrodes containing silicon-containing active materials, Sn negative electrodes containing tin-containing active materials, etc.) can absorb more Li ions than carbon negative electrodes (graphite and acetylene black, etc.). That is, the amount of Li ions absorbed per unit mass increases. Therefore, the battery capacity (energy density) can be increased. As a result, there is the advantage of being able to extend the battery life. Examples of silicon-containing active materials include Si and SiO. ｘ Silicon materials such as (0 < x ≤ 1), and also silicon-containing alloys containing titanium, vanadium, chromium, manganese, nickel, copper, lanthanum, etc. (for example, LaSi ２ , VSi ２ La-Si, Gd-Si, Ni-Si), or organized active material (e.g., LaSi ２ / Si), and also SnSiO ３ SnSiS ３ Examples include active materials containing silicon and tin elements. ｘ It can be used as a negative electrode active material (metallic oxide) itself, and since it generates Si through the operation of an all-solid-state secondary battery, it can be used as a negative electrode active material (its precursor material) that can be alloyed with lithium. Examples of negative electrode active materials containing the tin element include Sn, SnO, and SnO. ２ SnS, SnS ２Furthermore, active materials containing the above-mentioned silicon and tin elements are also mentioned. Also, composite oxides with lithium oxide, for example, Li ２ SnO ２ One could also list these.

[0136] In the present invention, the above-mentioned negative electrode active material can be used without particular limitation, but in terms of battery capacity, a negative electrode active material that can be alloyed with lithium is preferred as the negative electrode active material, and among these, the above-mentioned silicon material or silicon-containing alloy (alloy containing the element silicon) is more preferred, and it is even more preferred to contain silicon (Si) or a silicon-containing alloy.

[0137] The chemical formula of the compound obtained by the above calcination method can be calculated using inductively coupled plasma (ICP) emission spectroscopy as a measurement method, or, as a simpler method, from the mass difference of the powder before and after calcination.

[0138] The shape of the negative electrode active material is not particularly limited, but it is preferably particulate in the inorganic solid electrolyte-containing composition. When the negative electrode active material is particulate, the particle size of the negative electrode active material is not particularly limited, but it is preferably 0.1 to 60 μm. The particle size of the negative electrode active material particles can be prepared in the same manner as the particle size of the inorganic solid electrolyte, and the measurement method is also the same as the method for measuring the particle size of the inorganic solid electrolyte.

[0139] The inorganic solid electrolyte-containing composition may contain one or more types of negative electrode active materials. The content of the negative electrode active material in the inorganic solid electrolyte-containing composition is not particularly limited, but is preferably 10 to 90% by mass, more preferably 20 to 85% by mass, even more preferably 30 to 80% by mass, and still more preferably 40 to 75% by mass, based on 100% by mass of solid content.

[0140] In the present invention, when the negative electrode active material layer is formed by charging a secondary battery, ions of metals belonging to Group 1 or Group 2 of the periodic table, which are generated within the all-solid-state secondary battery, can be used instead of the negative electrode active material. By bonding these ions with electrons and depositing them as a metal, the negative electrode active material layer can be formed.

[0141] (Coating of Active Material) The surfaces of the positive electrode active material and the negative electrode active material may be coated with another metal oxide. Examples of surface coating agents include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. For example, spinel titanate, tantalum oxides, niobium oxides, lithium niobate compounds, etc. Specifically, Li ４ Ti ５ O １２ Li ２ Ti ２ O ５ , LiTaO ３ LiNbo ３ LiAlO ２ Li ２ ZrO ３ Li ２ WO ４ Li ２ TiO ３ Li ２ B ４ O ７ Li ３ PO ４ Li ２ MoO ４ Li ３ BO ３ LiBO ２ Li ２ CO ３ Li ２ SiO ３ SiO ２ , TiO ２ , ZrO ２ Al ２ O ３ , B ２ O ３ These are some examples. Furthermore, the electrode surface containing the positive electrode active material or negative electrode active material may be surface-treated with sulfur or phosphorus. In addition, the particle surface of the positive electrode active material or negative electrode active material may be surface-treated with active light or active gas (plasma, etc.) before or after the above surface coating.

[0142] [Conductive Additive] The inorganic solid electrolyte-containing composition of the present invention preferably contains a conductive additive. For example, the silicon-containing active material used as the negative electrode active material is preferably used in combination with a conductive additive. There are no particular restrictions on the conductive additive, and any commonly known conductive additive can be used. For example, it may be an electronically conductive material such as graphite, artificial graphite, or other graphites; carbon blacks such as acetylene black, Ketjen black, or furnace black; amorphous carbon such as needle coke; carbon fibers such as vapor-grown carbon fibers or carbon nanotubes; or carbonaceous materials such as graphene or fullerene. It may also be metal powders or metal fibers such as copper or nickel, or conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, or polyphenylene derivatives. In the present invention, when an active material and a conductive additive are used in combination, the conductive additive is one of the above conductive additives that does not function as an active material because insertion and release of metal ions (preferably Li ions) belonging to Group 1 or Group 2 of the periodic table does not occur when the battery is charged or discharged. Therefore, among conductive additives, those that can function as active materials in the active material layer when the battery is charged and discharged are classified as active materials, not conductive additives. Whether or not a conductive additive functions as an active material when the battery is charged and discharged is not singular, but is determined by its combination with the active material.

[0143] The conductive additive is preferably in particulate form in the inorganic solid electrolyte-containing composition. When the conductive additive is in particulate form, the particle size (volume average particle size) of the conductive additive is not particularly limited, but for example, 0.02 to 1.0 μm is preferred. The particle size of the conductive additive can be adjusted in the same way as the particle size of the inorganic solid electrolyte, and the measurement method is the same as the measurement method for the particle size of the inorganic solid electrolyte. The inorganic solid electrolyte-containing composition may contain one or two types of conductive additives. When the inorganic solid electrolyte-containing composition of the present invention contains a conductive additive, the content of the conductive additive in the inorganic solid electrolyte-containing composition is preferably 0 to 10% by mass, and more preferably 1 to 5% by mass, based on 100% by mass of solid content.

[0144] [Lithium Salt] The inorganic solid electrolyte-containing composition of the present invention may also preferably contain a lithium salt (supporting electrolyte). The lithium salt is preferably a lithium salt commonly used in this type of product, and is not particularly limited. For example, the lithium salt described in paragraphs 0082 to 0085 of Japanese Patent Application Publication No. 2015-088486 is preferred. When the inorganic solid electrolyte-containing composition of the present invention contains a lithium salt, the lithium salt content is preferably 0.1 parts by mass or more, and more preferably 5 parts by mass or more, per 100 parts by mass of the inorganic solid electrolyte. The upper limit is preferably 50 parts by mass or less, and more preferably 20 parts by mass or less.

[0145] [Dispersant] The inorganic solid electrolyte-containing composition of the present invention does not need to contain any other dispersants (referred to as "other dispersants") because the polymer binder described above also functions as a dispersant, but it may contain other dispersants. As other dispersants, those commonly used in all-solid-state secondary batteries can be appropriately selected and used. Generally, compounds intended for particle adsorption and steric repulsion and / or electrostatic repulsion are preferably used. The inorganic solid electrolyte-containing composition of the present invention may contain one or more other dispersants. When the inorganic solid electrolyte-containing composition of the present invention contains other dispersants, the amount of other dispersants can be appropriately determined, for example, it can be 3% by mass or less of 100% by mass of the solid content of the inorganic solid electrolyte-containing composition.

[0146] [Other Additives] The inorganic solid electrolyte-containing composition of the present invention may optionally contain, in addition to the above-mentioned components, ionic liquids, thickeners, crosslinking agents (such as those that undergo crosslinking reactions by radical polymerization, condensation polymerization, or ring-opening polymerization), polymerization initiators (such as those that generate acids or radicals by heat or light), defoaming agents, leveling agents, dehydrating agents, antioxidants, etc. The ionic liquid is included to further improve ionic conductivity, and known ionic liquids can be used without particular limitation. It may also contain polymers other than the binder-forming polymers mentioned above, commonly used binders, etc.

[0147] <Preparation of Inorganic Solid Electrolyte-Containing Composition> The inorganic solid electrolyte-containing composition of the present invention can be prepared as a mixture, preferably as a slurry, by mixing an inorganic solid electrolyte, the polymer binder mentioned above, a dispersion medium, preferably a conductive additive, and optionally a lithium salt and other components using various commonly used mixers. In the case of an electrode composition, an active material is further mixed. The mixing method is not particularly limited and can be carried out using known mixers such as ball mills, bead mills, planetary mixers, blade mixers, roll mills, kneaders, disc mills, revolving mixers, and narrow-gap dispersers. The mixing conditions are also not particularly limited. For example, each component may be mixed all at once or sequentially. As for the mixing conditions, for example, the mixing temperature can be 15 to 50°C. Also, the rotation speed of the revolving mixer, etc., can be 200 to 3000 rpm (rotation per minute). The mixing time is not particularly limited and can be appropriately determined according to the dispersibility of the solid particles, for example, it can be 1 to 180 minutes. The mixing atmosphere can be any of the following: air, dry air (dew point of -20°C or below), or in an inert gas (e.g., argon gas, helium gas, nitrogen gas). Since inorganic solid electrolytes readily react with moisture, mixing is preferably carried out in dry air or an inert gas. The inorganic solid electrolyte-containing composition of the present invention has excellent dispersion characteristics of solid particles, so it can be stored after preparation and does not need to be prepared each time it is used.

[0148] The inorganic solid electrolyte-containing composition of the present invention exhibits excellent dispersion stability (redispersibility) of solid particles, so it can be stored after preparation and does not need to be prepared each time it is used.

[0149] [Sheets for All-Solid-State Secondary Batteries] The sheets for all-solid-state secondary batteries of the present invention are sheet-like molded bodies capable of forming constituent layers of an all-solid-state secondary battery, and include various embodiments depending on their application. For example, these include sheets preferably used as solid electrolyte layers (also called solid electrolyte sheets for all-solid-state secondary batteries), electrodes, or sheets preferably used in laminates of electrodes and solid electrolyte layers (electrode sheets for all-solid-state secondary batteries). In the present invention, these various types of sheets are collectively referred to as sheets for all-solid-state secondary batteries. In the present invention, each layer constituting the sheet for all-solid-state secondary batteries may be a single-layer structure or a multi-layer structure.

[0150] The sheet for all-solid-state secondary batteries has a solid electrolyte layer or active material layer formed from the inorganic solid electrolyte-containing composition of the present invention. Therefore, the layer formed from the inorganic solid electrolyte-containing composition of the present invention is formed from components derived from the inorganic solid electrolyte-containing composition (excluding the dispersion medium), and is usually tightly bonded (bound) with solid particles (inorganic solid electrolyte and conductive additive, and furthermore, active material) and a polymer binder in a mixed state. By appropriately peeling off the substrate or incorporating the sheet as is into an all-solid-state secondary battery, it is possible to achieve low resistance (improved conductivity) and excellent high-potential cycle characteristics of the all-solid-state secondary battery.

[0151] The solid electrolyte sheet for all-solid-state secondary batteries of the present invention may be any sheet having a solid electrolyte layer, and may be a sheet in which the solid electrolyte layer is formed on a substrate, or a sheet without a substrate that is formed from the solid electrolyte layer (a sheet with the substrate peeled off). The solid electrolyte sheet for all-solid-state secondary batteries may have other layers in addition to the solid electrolyte layer. Examples of other layers include a protective layer (release sheet), a current collector, a coating layer, etc. The solid electrolyte layer of the solid electrolyte sheet for all-solid-state secondary batteries is preferably formed of the inorganic solid electrolyte-containing composition of the present invention. The content of each component in this solid electrolyte layer is not particularly limited, but is preferably the same as the content of each component in the solid content of the inorganic solid electrolyte-containing composition of the present invention. The thickness of each layer constituting the solid electrolyte sheet for all-solid-state secondary batteries is the same as the thickness of each layer described later in the all-solid-state secondary battery. An example of the solid electrolyte sheet for all-solid-state secondary batteries of the present invention is a sheet having, in this order, a layer composed of the inorganic solid electrolyte-containing composition of the present invention, a normal solid electrolyte layer, and a protective layer on a substrate.

[0152] The substrate is not particularly limited as long as it can support the solid electrolyte layer, and examples include sheets (plate-like bodies) of materials such as current collectors, organic materials, and inorganic materials, as described later. Examples of organic materials include various polymers, specifically polyethylene terephthalate, polypropylene, polyethylene, and cellulose. Examples of inorganic materials include glass and ceramics.

[0153] The electrode sheet for the all-solid-state secondary battery of the present invention (also simply referred to as "electrode sheet") may be any electrode sheet having an active material layer. This may be a sheet in which the active material layer is formed on a substrate (current collector), or a sheet without a substrate, formed solely from the active material layer (a sheet with the substrate peeled off). This electrode sheet is usually a sheet having a current collector and an active material layer, but it also includes embodiments having a current collector, an active material layer, and a solid electrolyte layer in this order, as well as embodiments having a current collector, an active material layer, a solid electrolyte layer, and an active material layer in this order. The solid electrolyte layer and active material layer of the electrode sheet are preferably formed from the inorganic solid electrolyte-containing composition of the present invention. The content of each component in this solid electrolyte layer or active material layer is not particularly limited, but is preferably synonymous with the content of each component in the solid content of the inorganic solid electrolyte-containing composition (electrode composition) of the present invention. The thickness of each layer constituting the electrode sheet of the present invention is the same as the thickness of each layer described later in the all-solid-state secondary battery. The electrode sheet may have other layers as described above. If the solid electrolyte layer or active material layer is not formed with the inorganic solid electrolyte-containing composition of the present invention, the solid electrolyte layer or active material layer can be formed using known materials.

[0154] The all-solid-state battery sheet of the present invention has at least one layer of the solid electrolyte layer and active material layer formed from the inorganic solid electrolyte-containing composition of the present invention. Therefore, the all-solid-state battery sheet of the present invention has a flat surface layer in which uniformly arranged solid particles are firmly bound together while suppressing an increase in the interfacial resistance of the solid particles. Therefore, by using this layer as a constituent layer of an all-solid-state battery, excellent high-potential cycle characteristics and low resistance (high conductivity) of the all-solid-state battery can be achieved. Furthermore, in an electrode sheet for an all-solid-state battery in which the active material layer on the current collector is formed from the inorganic solid electrolyte-containing composition of the present invention, the active material layer and the current collector can be firmly adhered to each other. Thus, the all-solid-state battery sheet of the present invention is suitably used as a sheet-like member for forming the constituent layers of an all-solid-state battery.

[0155] [[Method for Manufacturing All-Solid-State Secondary Battery Sheets]] The method for manufacturing the all-solid-state secondary battery sheet of the present invention is not particularly limited, and it can be manufactured by forming each of the above layers using the inorganic solid electrolyte-containing composition of the present invention. For example, preferably, a method is to form a layer (coated and dried layer) made of the inorganic solid electrolyte-containing composition by forming a film (coating and drying) on ​​a substrate or current collector (may be via other layers). This makes it possible to produce an all-solid-state secondary battery sheet having a substrate or current collector and a coated and dried layer. In particular, when the all-solid-state secondary battery sheet is manufactured by forming a film of the inorganic solid electrolyte-containing composition of the present invention on a current collector, the adhesion between the current collector and the active material layer can be strengthened. Here, the coated and dried layer refers to a layer formed by coating the inorganic solid electrolyte-containing composition of the present invention and drying the dispersion medium (i.e., a layer made using the inorganic solid electrolyte-containing composition of the present invention, and consisting of a composition obtained by removing the dispersion medium from the inorganic solid electrolyte-containing composition of the present invention). The active material layer and the coated and dried layer may have residual dispersion medium as long as it does not impair the effects of the present invention, and the residual amount can be, for example, 3% by mass or less in each layer. In the method for manufacturing a sheet for an all-solid-state secondary battery of the present invention, each step such as coating and drying will be explained in the method for manufacturing an all-solid-state secondary battery described below.

[0156] In the method for manufacturing a sheet for an all-solid-state secondary battery of the present invention, the coated and dried layer obtained as described above can also be pressurized. The pressurization conditions and other details will be explained later in the section on the method for manufacturing an all-solid-state secondary battery. Furthermore, in the method for manufacturing a sheet for an all-solid-state secondary battery of the present invention, the substrate, protective layer (especially the release sheet), etc., can also be peeled off.

[0157] [All-Solid-State Secondary Battery] The all-solid-state secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer facing the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The all-solid-state secondary battery of the present invention is not particularly limited in its other configurations, as long as it has a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer, and for example, known configurations relating to all-solid-state secondary batteries can be adopted. The positive electrode active material layer is preferably formed on a positive electrode current collector and constitutes the positive electrode. The negative electrode active material layer is preferably formed on a negative electrode current collector and constitutes the negative electrode. In the present invention, each constituent layer (including current collectors, etc.) constituting the all-solid-state secondary battery may be a single-layer structure or a multi-layer structure.

[0158] It is preferable that at least one of the negative electrode active material layer, positive electrode active material layer, and solid electrolyte layer is formed of the inorganic solid electrolyte-containing composition of the present invention. It is also preferable that at least one of the negative electrode active material layer and positive electrode active material layer is formed of the inorganic solid electrolyte-containing composition of the present invention. In the present invention, it is also preferable that all layers are formed of the inorganic solid electrolyte-containing composition of the present invention. In the present invention, forming the constituent layers of an all-solid-state secondary battery with the inorganic solid electrolyte-containing composition of the present invention includes the embodiment of forming the constituent layers with the sheet for the all-solid-state secondary battery of the present invention (provided that if the sheet has layers other than those formed of the inorganic solid electrolyte-containing composition of the present invention, these layers are removed). An all-solid-state secondary battery of the present invention, in which at least one of the constituent layers is formed of the inorganic solid electrolyte-containing composition of the present invention, exhibits low resistance (high conductivity) and excellent high-potential cycle characteristics. Because the all-solid-state secondary battery of the present invention exhibits low resistance and high ionic conductivity, it can also draw large currents. If the active material layer or solid electrolyte layer is not formed of the inorganic solid electrolyte-containing composition of the present invention, known materials can be used. In the present invention, each constituent layer (including current collectors, etc.) constituting the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

[0159] [Positive electrode active material layer, solid electrolyte layer, negative electrode active material layer] The active material layer or solid electrolyte layer formed with the inorganic solid electrolyte-containing composition of the present invention preferably contains the same types of components and their content as those in the solid content of the inorganic solid electrolyte-containing composition of the present invention. The thickness of the negative electrode active material layer, solid electrolyte layer, and positive electrode active material layer is not particularly limited. The thickness of each layer is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm, considering the dimensions of a typical all-solid-state secondary battery. In the all-solid-state secondary battery of the present invention, it is even more preferable that the thickness of at least one of the positive electrode active material layer and the negative electrode active material layer is 50 μm or more and less than 500 μm. The constituent layers having the above thickness may be single layers (one coating of the inorganic solid electrolyte-containing composition) or multi-layer layers (multiple coatings of the inorganic solid electrolyte-containing composition), but it is preferable to form a single-layer constituent layer with a large layer thickness using the inorganic solid electrolyte-containing composition of the present invention, which can be made into a thick layer by increasing the concentration, in terms of resistance reduction and productivity. The thickness of the thickened single layer of active material that can be preferably formed with the inorganic solid electrolyte-containing composition of the present invention can be, for example, 70 μm or more, and more preferably 100 μm or more.

[0160] [Current Collector] The positive electrode active material layer and the negative electrode active material layer may each have a current collector on the side opposite to the solid electrolyte layer. Electron conductors are preferred as the positive electrode current collector and the negative electrode current collector. In the present invention, either the positive electrode current collector or the negative electrode current collector, or both together, may be simply referred to as the current collector. As the material for forming the positive electrode current collector, in addition to aluminum, aluminum alloys, stainless steel, nickel, and titanium, a material in which carbon, nickel, titanium, or silver has been treated on the surface of aluminum or stainless steel (a thin film has been formed) is preferred, and aluminum and aluminum alloys are more preferred. As the material for forming the negative electrode current collector, in addition to aluminum, copper, copper alloys, stainless steel, nickel, and titanium, a material in which carbon, nickel, titanium, or silver has been treated on the surface of aluminum, copper, copper alloys, or stainless steel is preferred, and aluminum, copper, copper alloys, and stainless steel are more preferred.

[0161] While film sheets are typically used as the shape of the current collector, nets, punched materials, lath materials, porous materials, foams, and molded fiber bundles can also be used. The thickness of the current collector is not particularly limited, but 1 to 500 μm is preferred. It is also preferable to create an uneven surface on the current collector surface through surface treatment.

[0162] [Other configurations] In the present invention, functional layers or components may be appropriately interposed or arranged between or outside each layer of the negative electrode current collector, negative electrode active material layer, solid electrolyte layer, positive electrode active material layer, and positive electrode current collector.

[0163] [Housing] The all-solid-state secondary battery of the present invention may be used as an all-solid-state secondary battery with the above structure in place, depending on the application. However, to make it a dry cell, it is preferable to enclose it in a suitable housing. The housing may be made of metal or resin (plastic). When using a metal housing, examples include aluminum alloy or stainless steel. It is preferable that the metal housing be divided into a positive electrode housing and a negative electrode housing, and that these be electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. It is preferable that the positive electrode housing and the negative electrode housing are joined together and integrated via a gasket to prevent short circuits.

[0164] A preferred embodiment of the all-solid-state secondary battery of the present invention will be described below with reference to Figure 1, but the present invention is not limited thereto.

[0165] Figure 1 is a schematic cross-sectional view showing an all-solid-state secondary battery (lithium-ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 of this embodiment has, when viewed from the negative electrode side, a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in this order. Each layer is in contact with the others and has an adjacent structure. By adopting such a structure, during charging, electrons (e － ) is supplied, and lithium ions (Li ＋ ) accumulates. On the other hand, during discharge, lithium ions (Li) accumulated on the negative electrode ＋The discharge is returned to the positive electrode side, and electrons are supplied to the working part 6. In the illustrated example, a light bulb is used as a model for the working part 6, and it is designed to light up when the discharge occurs.

[0166] When an all-solid-state secondary battery having the layer configuration shown in Figure 1 is placed in a 2032 type coin case 11 (see, for example, Figure 2), this all-solid-state secondary battery is sometimes referred to as the all-solid-state secondary battery laminate 12, and the battery produced by placing this all-solid-state secondary battery laminate 12 in the 2032 type coin case 11 is sometimes referred to as the (coin-type) all-solid-state secondary battery 13.

[0167] <Positive electrode active material layer, solid electrolyte layer, negative electrode active material layer> In the all-solid-state secondary battery 10, the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 are all formed from the inorganic solid electrolyte-containing composition of the present invention. The inorganic solid electrolyte and polymer binder contained in the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 may be of the same type or different types. In addition, the conductive additives contained in the positive electrode active material layer 4 and the negative electrode active material layer 2 may be of the same type or different types. In the present invention, either the positive electrode active material layer or the negative electrode active material layer, or both together, may be simply referred to as the active material layer or electrode active material. In addition, either the positive electrode active material or the negative electrode active material, or both together, may be simply referred to as the active material or electrode active material.

[0168] The solid electrolyte layer contains an inorganic solid electrolyte having conductivity for metal ions belonging to Group 1 or Group 2 of the periodic table, a polymer binder, and any of the above-mentioned components, etc., to the extent that they do not impair the effects of the present invention, and usually does not contain a positive electrode active material and / or a negative electrode active material. The positive electrode active material layer contains an inorganic solid electrolyte having conductivity for metal ions belonging to Group 1 or Group 2 of the periodic table, a polymer binder, a positive electrode active material, and any of the above-mentioned components, etc., to the extent that they do not impair the effects of the present invention. The negative electrode active material layer contains an inorganic solid electrolyte having conductivity for metal ions belonging to Group 1 or Group 2 of the periodic table, a polymer binder, a negative electrode active material, and any of the above-mentioned components, etc., to the extent that they do not impair the effects of the present invention. In the all-solid-state secondary battery 10, the negative electrode active material layer can be a lithium metal layer. Examples of lithium metal layers include layers formed by depositing or molding lithium metal powder, lithium foil, and lithium vapor-deposited films. The thickness of the lithium metal layer can be, for example, 1 to 500 μm, regardless of the thickness of the negative electrode active material layer.

[0169] In the present invention, by forming the constituent layer with the inorganic solid electrolyte-containing composition of the present invention, an all-solid-state secondary battery with excellent high-potential cycle characteristics and low resistance can be realized.

[0170] <Current Collectors> The positive electrode current collector 5 and the negative electrode current collector 1 are as described above. In the case of an all-solid-state secondary battery 10 having constituent layers other than those formed from the inorganic solid electrolyte-containing composition of the present invention, layers formed from known constituent layer-forming materials may also be used. Furthermore, each layer may consist of a single layer or multiple layers.

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

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

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

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

[0175] [Formation of each layer (film formation)] The method of coating the inorganic solid electrolyte-containing composition is not particularly limited and can be selected as appropriate. Examples include coating (preferably wet coating), spray coating, spin coating, dip coating, slit coating, stripe coating, and bar coating. The coating temperature is not particularly limited and is typically in a temperature range of around room temperature (e.g., 15 to 30°C) without heating. At this time, the inorganic solid electrolyte-containing composition may be dried after each coating, or dried after multi-layer coating. The drying temperature is not particularly limited. The lower limit is preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. The upper limit is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. By heating within this temperature range, the dispersion medium can be removed and the mixture can be converted into a solid state (coated and dried layer). This is also preferable because it avoids excessively high temperatures and thus prevents damage to the components of the all-solid-state secondary battery. This makes it possible to achieve excellent overall performance, good bonding properties, and good ionic conductivity in all-solid-state secondary batteries.

[0176] It is preferable to pressurize each layer or the all-solid-state secondary battery after applying the inorganic solid electrolyte-containing composition, stacking the constituent layers, or after manufacturing the all-solid-state secondary battery. It is also preferable to pressurize the layers in a stacked state. Examples of pressurizing methods include hydraulic cylinder presses. The pressurizing pressure is not particularly limited, but is generally preferably in the range of 5 to 1500 MPa. The applied inorganic solid electrolyte-containing composition may also be heated simultaneously with pressurizing. The heating temperature is not particularly limited, but is generally in the range of 30 to 300°C. Pressing can also be performed at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. Furthermore, pressing can also be performed at a temperature higher than the glass transition temperature of the polymer contained in the polymer binder. However, generally, the temperature should not exceed the melting point of the polymer. Pressurizing may be performed with the coating solvent or dispersion medium pre-dried, or with residual solvent or dispersion medium. Each composition may be applied simultaneously, or the coating, drying, and pressing may be performed simultaneously and / or sequentially. The compositions may also be applied to separate substrates and then stacked by transfer.

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

[0178] The inorganic solid electrolyte-containing composition of the present invention maintains excellent dispersion stability, handling properties, and initial dispersibility even when the solid content concentration is increased. Therefore, the inorganic solid electrolyte-containing composition can be applied at a high solid content concentration.

[0179] [Initialization] It is preferable to initialize the all-solid-state secondary battery manufactured as described above after manufacturing or before use. Initialization is not particularly limited and can be performed, for example, by performing the initial charge and discharge with increased press pressure, and then releasing the pressure until it reaches the general operating pressure of the all-solid-state secondary battery.

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

[0181] The present invention will be described in more detail below based on examples, but the present invention is not to be construed as being limited thereto. In the following examples, "parts" and "%" representing the composition are by mass unless otherwise specified. In the present invention, "room temperature" means 25°C.

[0182] [Synthesis Example] Polymer Synthesis and Binder Solution Preparation The polymers shown in the following chemical formulas and Table 1 were synthesized as follows, and a binder solution or dispersion was prepared. [Synthesis Example B-1: Synthesis of Polymer B-1 and Preparation of Binder Solution B-1] 96 g of decyl methacrylate, 18 g of dodecyl acrylate, 6 g of 2-hydroxyethyl methacrylate, and 0.12 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a 200 mL graduated cylinder and dissolved in 10 g of butyl butyrate to prepare a monomer solution. 28 g of butyl butyrate was added to a 500 mL three-necked flask and stirred at 80°C under a nitrogen stream. A solution of 2 g of butyl butyrate with 0.08 g of polymerization initiator V-601 was added. After 10 minutes, the above monomer solution was added dropwise over 3 hours. After the dropwise addition was complete, the mixture was stirred for 2 hours. Then, a solution of 0.2 g of polymerization initiator V-601 dissolved in 11 g of butyl butyrate was added over 30 minutes, and the mixture was stirred for another 2 hours. After that, it was cooled to room temperature and left overnight. The next day, the mixture was stirred at 80°C under a nitrogen stream, and a solution of 0.2 g of polymerization initiator V-601 dissolved in 2 g of butyl butyrate was added. The mixture was stirred for another 2 hours. After that, a solution of 0.2 g of polymerization initiator V-601 dissolved in 2 g of butyl butyrate was added, and the mixture was stirred for another 2 hours. This procedure was repeated once more, and then 220 g of butyl butyrate was added to dilute the mixture. The temperature was then raised to 90°C and stirred for 3 hours, after which it was cooled to room temperature. In this way, polymer B-1 was synthesized, and a binder solution B-1 (concentration approximately 30% by mass) consisting of this polymer was obtained.

[0183] [Synthesis Examples B-2 to B-15: Synthesis of Polymers B-2 to B-15 and Preparation of Binder Solutions B-2 to B-15] Except that the compounds used to derive each constituent unit were used so that polymers B-2 to B-15 have the chemical formulas and compositions (types and content of constituent units) shown in Table 1 below, and the amount of polymerization initiator and polymerization concentration were adjusted so that the weight-average molecular weights shown in Table 1, polymers B-2 to B-15 were synthesized in the same manner as in Synthesis Example B-1, and binder solutions B-2 to B-15 consisting of each polymer were obtained.

[0184] [Synthesis Example BT-1: Synthesis of Polymer BT-1 and Preparation of Binder Solution BT-1] 200 g of deionized water, 166 g of vinylidene fluoride, and 34 g of hexafluoropropylene were added to an autoclave, and 2 g of diisopropyl peroxydicarbonate was added. The mixture was stirred at 30°C for 24 hours. After polymerization was complete, the precipitate was filtered and dried at 100°C for 10 hours to obtain polymer (binder) BT-1. The obtained polymer was dissolved in butyl butyrate to obtain a binder solution.

[0185] [Synthesis Examples BT-2 to BT-4 and BT-6: Synthesis of polymers BT-2 to BT-4 and BT-6, and preparation of binder solutions BT-2 to BT-4 and BT-6] Except that the polymers BT-2 to BT-4 and BT-6 were synthesized in the same manner as in Synthesis Example B-1, using compounds to derive each constituent unit so that polymers BT-2 to BT-4 and BT-6 have the chemical formulas and compositions (types and content of constituent units) shown in Table 1 below, and the amount of polymerization initiator was adjusted so that the weight-average molecular weight was as shown in Table 1, polymers BT-2 to BT-4 and BT-6 were synthesized in the same manner as in Synthesis Example B-1, and binder solutions BT-2 to BT-4 and BT-6, each consisting of the respective polymers, were obtained.

[0186] [Synthesis Example BT-5: Synthesis of Polymer BT-5 and Preparation of Binder Solution BT-5] <Synthesis of Macromonomer MM-1> In a 500 mL graduated cylinder, 73.4 g of dodecyl acrylate 136.6, 1H,1H,2H,2H-tridecafluorooctyl methacrylate, 3.9 g of 3-mercaptopropionic acid, and 4.2 g of polymerization initiator V-601 were added and dissolved in 57 g of butyl butyrate to prepare the monomer solution. 71 g of butyl butyrate was added to a 1 L three-necked flask and stirred at 80°C under a nitrogen stream. The monomer solution was then added dropwise over 2 hours and stirred for another 2 hours at 80°C. After adding another 0.42 g of polymerization initiator V-601, the temperature was raised to 95°C and stirred for another 2 hours. To the obtained solution, 6.2 g of glycidyl methacrylate, 0.2 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical, and 2.6 g of tetrabutylammonium bromide were added and the mixture was stirred at 100°C for 3 hours. The obtained reaction solution was reprecipitated with methanol to synthesize macromonomer MM-1. The number-average molecular weight of the obtained macromonomer MM-1 was 5000. <Synthesis of polymer BT-5> Next, polymer BT-5 was synthesized in the same manner as in synthesis example B-1, except that compounds were used to derive each constituent unit so that polymer BT-5 would have the chemical formula and composition (type and content of constituent units) shown in Table 1 below, and the amount of polymerization initiator was adjusted so that the weight-average molecular weight shown in Table 1, to obtain binder solution BT-5 consisting of each polymer.

[0187] The chemical formulas of each synthesized polymer are shown below. In the chemical formulas below, "Me" represents a methyl group, "Ph" represents a phenyl group, "LA" represents dodecyl acrylate, and "F13MA" represents 1H,1H,2H,2H-tridecafluorooctyl methacrylate.

[0188]

[0189] For each constituent unit, the values ​​calculated according to the above method for the HOMO energy level E (eV), the maximum positive charge σ on the carbon atom, and the relationship defined by formula (1) and formula (2), as well as formula (3), are listed in the "E (eV)", "σ", and "Formula (3)" columns of Table 1, respectively. For constituent units having a "polymerization chain" in the side chain, the calculations were performed using a structure in which the bond connecting to the repeating chain was broken and replaced with a hydrogen atom. Specifically, the constituent unit MM-1 in comparative example polymer BT-5 was converted to the following structure for calculation.

[0190]

[0191] In Table 1, the "Formula (3)" column indicates the satisfaction of Formula (3) for each constituent unit, with "○" indicating satisfaction and "×" indicating non-satisfaction. Furthermore, for each constituent unit, "○" indicates satisfaction of the relationships represented by Formulas (3A) and (3B), and "×" indicates non-satisfaction, as recorded in the "Formula (3A)" and "Formula (3B)" columns of the table. The total content of constituent unit (D) in each polymer is also recorded in the "Total Content (mass%)" column of Table 1. The "Content (mass%)" and "Total Content (mass%)" values ​​for each constituent unit listed in Table 1 are calculated from the input ratios of each compound during preparation. Additionally, the weight-average molecular weight of each polymer, measured according to the above method, is recorded in the "Mw (k)" column of Table 1. Note that "k" in this column represents "×10 ３ This means "dissolved". In the "State" column of Table 1, the state of the polymer binder in each composition described later is shown based on the results of measuring the solubility in the dispersion medium using the method described above, and is judged to be either "dissolved" or "particulate" (dispersed as particulate without dissolving). The acid values ​​of polymers B-1 to B-14 were all "0 mmol / g", and the acid value of B-15 was "0.23 mmol / g".

[0192]

[0193] <Abbreviations in the Table> In the table, "-" in the "Constituent Unit" column indicates that the corresponding constituent unit is not present. The abbreviations indicating the type of each constituent unit (the compound name that derives each constituent unit) in Table 1 are as follows: DMA: n-decyl methacrylate (synthesized by the method described in the following reference: Macromolecules 2006, 39, 1156-1159) MMA: methyl methacrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) CyHMA: cyclohexyl methacrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) LMA: n-dodecyl methacrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) St: styrene (Fujifilm Wako Pure Chemical Industries, Ltd.) MM-1: macromonomer MM-1 synthesized in synthesis example T-5 F13MA: 1H,1H,2H,2H-tridecafluoro-n-octyl methacrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) HEMA: 2-hydroxyethyl methacrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) PEMA: 2-phenoxyethyl methacrylate (manufactured by Tokyo Chemical Industries, Ltd.) THFA: Tetrahydrofurfuryl acrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) DEGMEM: 2-(2-methoxyethoxy)ethyl methacrylate (manufactured by Tokyo Chemical Industries, Ltd.) NIPAM: N-isopropylacrylamide (Fujifilm Wako Pure Chemical Industries, Ltd.) LAAm: N-dodecylacrylamide (manufactured by Tokyo Chemical Industries, Ltd.) DEAA: Diethylacrylamide (Fujifilm Wako Pure Chemical Industries, Ltd.) NLMI: N-dodecylmaleimide (synthesized by the method described in the following reference: Organic Chemistry Frontiers 2024, 11(22), 6503-6509) EtMI: N-ethylmaleimide (Fujifilm Wako Pure Chemical Industries, Ltd.) CyHMI: N-cyclohexylmaleimide (Fujifilm Wako Pure Chemical Industries, Ltd.) AA: Acrylic acid (Fujifilm Wako Pure Chemical Industries, Ltd.) LA: n-dodecyl acrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) VDF: Vinylidene fluoride (Nacalai Tesque Co., Ltd.) HFP: Hexafluoropropylene (Tokyo Chemical Industries, Ltd.) BA: n-butyl acrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) DMAEMA: 2-dimethylaminoethyl methacrylate (Fujifilm Wako Pure Chemical Industries, Ltd.) AN: Acrylonitrile (Fujifilm Wako Pure Chemical Industries, Ltd.) HEA: 2-hydroxyethyl acrylate (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0194] [Synthesis Example A: Synthesis of Sulfide-Based Inorganic Solid Electrolytes] Sulfide-based inorganic solid electrolytes were synthesized with reference to the non-patent literature of T. Ohtomo, A. Hayashi, M. Tatsumisago, Y. Tsuchida, S. Hama, K. Kawamoto, Journal of Power Sources, 233, (2013), pp. 231-235, and A. Hayashi, S. Hama, H. Morimoto, M. Tatsumisago, T. Minami, Chem. Lett., (2001), pp. 872-873. Specifically, in a glove box under an argon atmosphere (dew point -70°C), lithium sulfide (Li ２ S, Aldrich, purity >99.98%, 2.42g and phosphorus pentasulfide (P ２ S ５ 3.90 g each of Aldrich (purity >99%) was weighed out and placed in an agate mortar, and mixed for 5 minutes using an agate pestle. ２ S and P ２ S ５ The mixing ratio is Li in molar ratio. ２ S:P ２ S ５ The ratio was set to 75:25. Next, 66 g of 5 mm diameter zirconia beads were placed in a 45 mL zirconia container (manufactured by Fritsch), and the entire amount of the above-mentioned mixture of lithium sulfide and phosphorus pentasulfide was added. The container was then completely sealed under an argon atmosphere. The container was set in a planetary ball mill P-7 (trade name, manufactured by Fritsch), and mechanical milling was performed at a temperature of 25°C and a rotation speed of 510 rpm for 20 hours to obtain 6.20 g of yellow powder sulfide-based inorganic solid electrolyte (Li-P-S glass, hereinafter sometimes referred to as LPS). The particle size of the Li-P-S glass was 15 μm.

[0195] [Example 1] Each composition shown in Tables 2-1 to 2-4 (collectively referred to as Table 2) was prepared as follows. <Preparation of Inorganic Solid Electrolyte-Containing Compositions> 2.8 g of the inorganic solid electrolyte LPS synthesized in Synthesis Example A, 0.08 g (solid content mass) of the binder solution, and butyl butyrate as the dispersion medium were added to a container for a rotary mixer (ARE-310, manufactured by Thinky Co., Ltd.) so that the dispersion medium content in the composition was 48% by mass. Then, this container was set in the rotary mixer ARE-310 (product name). Mixing was performed at 25°C and a rotation speed of 2000 rpm for 5 minutes to prepare inorganic solid electrolyte-containing compositions (slurries) K-1 to K-15, respectively. Furthermore, inorganic solid electrolyte-containing compositions (slurries) Kc11 to Kc16 were prepared in the same manner as in the preparation of inorganic solid electrolyte-containing composition K-1, except that the binder solution was changed to the binder solution shown in Table 2-4 and the content of each component was set to the content shown in the same table.

[0196] <Preparation of Cathode Composition> 2.8 g of the inorganic solid electrolyte LPS synthesized in Synthesis Example A and xylene as a dispersion medium were added to a container for a rotary-rotating mixer (ARE-310, manufactured by Thinky Co., Ltd.) so that the dispersion medium content in the cathode composition was 30% by mass. Then, this container was set in the rotary-rotating mixer ARE-310 (product name) and mixed for 2 minutes at a temperature of 25°C and a rotation speed of 2000 rpm. Then, LiNi was added to this container as the cathode active material in the proportions shown in Table 2-2. １／３ Co １／３ Mn １／３ O ２ (NMC, manufactured by Aldrich Corporation), acetylene black (AB) as a conductive additive, and the binder solution shown in Table 2-2 below were added and set in a rotary-rotating mixer ARE-310 (product name). Mixing was carried out for 2 minutes at 25°C and a rotation speed of 2000 rpm to prepare positive electrode compositions (slurries) PK-1 to PK-15. Furthermore, positive electrode compositions (slurries) PKc21 to PKc26 were prepared in the same manner as in the preparation of positive electrode composition PK-1, except that the binder solution was changed to the binder solution shown in Table 2-4 and the content of each component was set to the content shown in the same table.

[0197] <Preparation of Negative Electrode Composition> Into a container for a rotation-revolution mixer (ARE-310), 2.8 g of the inorganic solid electrolyte LPS synthesized in Synthesis Example A, 0.06 g (by mass of solid content) of the binder solution shown in Table 2-3 below, and xylene as a dispersion medium were added so that the content of the dispersion medium in the negative electrode composition was 48% by mass. Thereafter, this container was set in a rotation-revolution mixer ARE-310 (trade name, manufactured by Thinky Corporation), and mixed for 2 minutes at 25°C and a rotation speed of 2000 rpm. Thereafter, 3.36 g of graphite (Gr, manufactured by Aldrich) as the negative electrode active material shown in Table 2-3 below (for Examples NK-4, NK-10, and NK-13, 3.11 g of graphite and 0.25 g of carbon nanotubes (VGCF) as a conductive aid) were added, and the mixture was similarly set in the rotation-revolution mixer ARE-310 (trade name), and mixed for 2 minutes at 25°C and a rotation speed of 2000 rpm, to prepare negative electrode compositions (slurries) NK-1 to NK-15, respectively. Further, in the preparation of negative electrode composition NK-1, negative electrode compositions (slurries) NKc21 to NKc26 were each prepared in the same manner except that the binder solution was changed to the binder solution shown in Table 2-4, and the content of each component was set to the content shown in the same table.

[0198] In Table 2, the composition content is the content (% by mass) relative to the total mass of the composition, and the solid content is the content (% by mass) relative to 100% by mass of the solid content of the composition. The unit is omitted in the table.

[0199]

[0200]

[0201]

[0202]

[0203] <Abbreviations in Table> LPS: LPS synthesized in Synthesis Example A NMC: LiNi １／３ Co １／３ Mn １／３ O ２ AB: acetylene black Gr: graphite (manufactured by Aldrich) VGCF: carbon nanofiber

[0204] <Preparation of Solid Electrolyte Sheet for All-Solid-State Secondary Battery> Each inorganic solid electrolyte-containing composition obtained above, as shown in the column "Solid Electrolyte Composition No." of Table 3-1 or Table 3-4, was coated on an aluminum foil with a thickness of 20 μm using a Baker-type applicator (trade name: SA-201, manufactured by Tester Sangyo Co., Ltd.), and heated at 80°C for 2 hours to dry the inorganic solid electrolyte-containing composition (remove the dispersion medium). Thereafter, using a heat press, the dried inorganic solid electrolyte-containing composition was heated and pressed at a temperature of 120°C and a pressure of 10 MPa for 10 seconds, to prepare solid electrolyte sheets for all-solid-state secondary batteries (referred to as solid electrolyte sheets in Tables 3-1 and 3-4) 101 to 115 and c11 to c16, respectively. The film thickness of the solid electrolyte layer was 50 μm.

[0205] <Preparation of Positive Electrode Sheet for All-Solid-State Secondary Battery> Each positive electrode composition obtained above, as shown in the column "Electrode Composition No." of Table 3-2 or Table 3-4, was coated on an aluminum foil with a thickness of 20 μm using a Baker-type applicator (trade name: SA-201), heated at 80°C for 1 hour, and further heated at 110°C for 1 hour to dry the positive electrode composition (remove the dispersion medium). Thereafter, using a heat press, the dried positive electrode composition was pressed at 25°C (10 MPa, 1 minute), to prepare positive electrode sheets for all-solid-state secondary batteries having a positive electrode active material layer with a film thickness of 100 μm (referred to as positive electrode sheets in Tables 3-2 and 3-4) 201 to 215 and c21 to c26, respectively.

[0206] <Preparation of Negative Electrode Sheet for All-Solid-State Secondary Battery> Each negative electrode composition obtained above, as shown in the column "Electrode Composition No." of Table 3-3 or Table 3-4, was coated on a copper foil with a thickness of 20 μm using a Baker-type applicator (trade name: SA-201), heated at 80°C for 1 hour, and further heated at 110°C for 1 hour to dry the negative electrode composition (remove the dispersion medium). Thereafter, using a heat press, the dried negative electrode composition was pressed at 25°C (10 MPa, 1 minute), to prepare negative electrode sheets for all-solid-state secondary batteries having a negative electrode active material layer with a film thickness of 70 μm (referred to as negative electrode sheets in Tables 3-3 and 3-4) 301 to 315 and c31 to c36, respectively.

[0207] <Evaluation 1: Storage Stability Test (Redispersibility)> For each composition prepared as described above, LPS, polymer binder, dispersion medium, active material, and conductive additive were mixed in the same proportions as the composition content and solid content shown in Table 2, under the same preparation conditions as for each composition, to prepare a composition (slurry) for dispersibility evaluation. For each prepared composition, the presence or absence of aggregates of solid particles was confirmed using a grindometer (manufactured by Asahi Research Institute Co., Ltd.). The size of the aggregates at this time was defined as X (μm) and used as an indicator of initial dispersibility. On the other hand, after leaving each prepared composition at 25°C for 24 hours, it was mixed again at a temperature of 25°C using a planetary ball mill P-7 (product name). The rotation speed and time during remixing were the same as the preparation conditions for each composition (25°C, 2000 rpm, 2 minutes for the electrode composition). For the remixed composition, the presence or absence of aggregates of solid particles was confirmed using the grindometer described above. The size of the aggregates at this time was defined as Y (μm) and used as an indicator of redispersibility after storage. The size of the aggregates was defined as the point at which a noticeable spot appeared on the grindometer (see JIS K-5600-2-5 6.6). The ease of aggregate formation (aggregation or sedimentation) was evaluated as the storage stability (redispersibility of solid particles) of the composition, depending on whether the aggregate sizes X and Y fell into any of the evaluation criteria below. In this test, a smaller aggregate size X indicates superior initial dispersibility, and a smaller size Y indicates superior storage stability. If a composition can effectively suppress (re)aggregation or sedimentation of solid particles over time (excellent dispersion stability), then even solid particles that have aggregated or settled can reproduce the excellent dispersibility immediately after preparation, demonstrating excellent storage stability. In this test, an evaluation criterion of "C" or higher for aggregate size Y was considered a passing level, and if size Y was 8 μm or less (evaluation criterion "C" or higher), aggregate size X was also included in the evaluation. The results are shown in Tables 3-1 to 3-4. Hereinafter, Tables 3-1 to 3-4 are collectively referred to as Table 3.- Evaluation Criteria - A: Y ≤ 5 μm and X ≤ 5 μm B: 5 μm < Y ≤ 8 μm and 5 μm < X ≤ 8 μm C: 5 μm < Y ≤ 8 μm and 8 μm < X ≤ 12 μm D: 8 μm < Y ≤ 10 μm E: 10 μm < Y ≤ 20 μm F: 20 μm < Y.

[0208] <Evaluation 2: Handling Test> In the same manner as the prepared compositions, a slurry with a solid content of 75% by mass was prepared by reducing the amount of dispersion medium, while maintaining the same mixing ratio except for the dispersion medium. A 2 mL poly pipette (manufactured by Atect Co., Ltd.) was positioned vertically so that the tip 10 mm was below the slurry interface, and the slurry was aspirated for 10 seconds at 25°C. The mass W of the poly pipette containing the aspirated slurry was measured. The tare weight (self-weight) of the poly pipette was W. ０ In this case, the slurry mass W - W ０ It was determined that the slurry could not be drawn up with a dropper if the solid content was less than 0.1 g. If the slurry could not be drawn up with a dropper, the upper limit solid content concentration that could be drawn up with a dropper was determined by gradually adding the dispersion medium. The handling properties of the composition (whether it has an appropriate viscosity to form a flat, good surface layer) were evaluated based on whether the obtained upper limit solid content concentration fell within one of the evaluation criteria below. The solid content concentration was calculated by placing 0.30 g of the prepared slurry on an aluminum cup and heating it at 120°C for 2 hours to remove the dispersion medium by distillation. In this test, a higher upper limit solid content concentration indicated better handling properties, and an evaluation criterion of "C" or higher was considered a passing level. The results are shown in Table 3. - Evaluation Criteria - A: Upper limit solid content concentration ≥ 70% B: 70% > Upper limit solid content concentration ≥ 60% C: 60% > Upper limit solid content concentration ≥ 50% D: 50% > Upper limit solid content concentration ≥ 40% E: 40% > Upper limit solid content concentration ≥ 30% F: 30% > Upper limit solid content concentration

[0209] <Evaluation 3: Adhesion Test> The adhesion of solid particles and adhesion to the current collector were evaluated for each obtained sheet for solid-state secondary batteries. Each prepared sheet for solid-state secondary batteries was cut into a rectangle measuring 3 cm wide x 14 cm long. Using a cylindrical mandrel tester (product code 056, mandrel diameter 10 mm, Allgood), one end of the cut sheet test piece in the longitudinal direction was fixed to the tester, and the cylindrical mandrel was positioned so that it touched the center of the sheet test piece. The other end of the sheet test piece in the longitudinal direction was pulled along the length direction with a force of 5 N, and bent 180° along the circumference of the mandrel (with the mandrel as the axis). The sheet test piece was set with the solid electrolytic layer or active material layer on the opposite side from the mandrel (the base material or current collector on the mandrel side), and the width direction parallel to the axis of the mandrel. The test was conducted by gradually decreasing the diameter of the mandrel from 32 mm. The evaluation was performed by measuring the minimum diameter at which no defects (cracks, fractures, chips, etc.) due to the breakdown of solid particles in the solid electrolytic layer or active material layer, and no separation between the solid electrolytic layer or active material layer and the current collector were observed, both when the material was wound around a mandrel and when it was unwound and restored to a sheet form. The evaluation was then conducted based on which of the following evaluation criteria this minimum diameter fell into. In this test, the smaller the minimum diameter, the stronger the bonding force of the solid particles constituting the solid electrolytic layer or active material layer, and the stronger the adhesion force between the solid electrolytic layer or active material layer and the current collector. An evaluation of "C" or higher is considered a passing level. - Evaluation Criteria - A: Minimum diameter < 5 mm B: 5 mm ≤ Minimum diameter < 6 mm C: 6 mm ≤ Minimum diameter < 8 mm D: 8 mm ≤ Minimum diameter < 10 mm E: 10 mm ≤ Minimum diameter < 14 mm F: 14 mm ≤ Minimum diameter < 25 mm G: 25 mm ≤ Minimum diameter

[0210]

[0211]

[0212]

[0213]

[0214] <Manufacturing of All-Solid-State Rechargeable Batteries> First, a positive electrode sheet for all-solid-state rechargeable batteries, equipped with a solid electrolyte layer, and a negative electrode sheet for all-solid-state rechargeable batteries, equipped with a solid electrolyte layer, were manufactured for use in the production of all-solid-state rechargeable batteries.

[0215] - Fabrication of positive electrode sheets for all-solid-state secondary batteries equipped with a solid electrolyte layer - On the positive electrode active material layer of each positive electrode sheet for all-solid-state secondary batteries shown in the "Electrode Active Material Layer (Sheet No.)" column of Table 4, the solid electrolyte sheet fabricated above, as shown in the "Solid Electrolyte Layer (Sheet No.)" column of Table 4, was placed so that the solid electrolyte layer was in contact with the positive electrode active material layer. After transferring (laminating) by applying pressure of 50 MPa at 25°C using a press machine, the sheets were then pressurized at 600 MPa at 25°C to produce positive electrode sheets for all-solid-state secondary batteries (positive electrode active material layer thickness of 50 μm) Nos. 201 to 215 and c21 to c26, each equipped with a solid electrolyte layer with a thickness of 25 μm.

[0216] - Fabrication of negative electrode sheets for all-solid-state secondary batteries equipped with a solid electrolyte layer - On the negative electrode active material layer of each negative electrode sheet for all-solid-state secondary batteries shown in the "Electrode Active Material Layer (Sheet No.)" column of Table 4, the solid electrolyte sheet fabricated above, shown in the "Solid Electrolyte Layer (Sheet No.)" column of Table 4, was placed so that the solid electrolyte layer was in contact with the negative electrode active material layer. After transferring (laminating) by applying pressure of 50 MPa at 25°C using a press, the sheets were then pressurized at 600 MPa at 25°C to produce negative electrode sheets for all-solid-state secondary batteries (negative electrode active material layer thickness 40 μm) 301 to 315 and c31 to c36, respectively, equipped with a solid electrolyte layer with a thickness of 25 μm.

[0217] A solid-state secondary battery No. 101 having the layer configuration shown in Figure 1 was fabricated as follows. The positive electrode sheet No. 201 for a solid-state secondary battery (with the aluminum foil removed from the solid electrolyte-containing sheet) obtained above, which has a solid electrolyte layer, was cut into a disc shape with a diameter of 14.5 mm and placed in a stainless steel 2032 type coin case 11 incorporating a spacer and a washer (not shown in Figure 2), as shown in Figure 2. Next, a lithium foil cut into a disc shape with a diameter of 15 mm was placed on top of the solid electrolyte layer. After further stacking of stainless steel foil on top of that, the 2032 type coin case 11 was crimped to produce the solid-state secondary battery No. 101 shown in Figure 2. The solid-state secondary battery produced in this way has the layer configuration shown in Figure 1 (wherein the lithium foil corresponds to the negative electrode active material layer 2 and the negative electrode current collector 1).

[0218] In the manufacture of the above-mentioned all-solid-state secondary battery No. 101, all-solid-state secondary batteries Nos. 102 to 115 and c101 to c106 were manufactured in the same manner as the manufacture of all-solid-state secondary battery No. 101, except that a positive electrode sheet for all-solid-state secondary batteries with a solid electrolyte layer, represented by the No. shown in the "Electrode Active Material Layer (Sheet No.)" column of Table 4, was used instead of the positive electrode sheet for all-solid-state secondary batteries with a solid electrolyte layer, No. 201, which has a solid electrolyte layer.

[0219] A solid-state secondary battery No. 201 having the layer configuration shown in Figure 1 was fabricated as follows. The negative electrode sheet No. 301 for solid-state secondary batteries (with the aluminum foil removed from the solid electrolyte-containing sheet) obtained above was cut into a disc shape with a diameter of 14.5 mm and placed in a stainless steel 2032 type coin case 11 incorporating a spacer and a washer (not shown in Figure 2), as shown in Figure 2. Next, a positive electrode sheet (positive electrode active material layer) punched out with a diameter of 14.0 mm from the positive electrode sheet for solid-state secondary batteries fabricated below was placed on top of the solid electrolyte layer. A stainless steel foil (positive electrode current collector) was further placed on top to form a laminate 12 for solid-state secondary batteries (a laminate consisting of stainless steel foil - aluminum foil - positive electrode active material layer - solid electrolyte layer - negative electrode active material layer - copper foil). After that, the 2032 type coin case 11 was crimped to manufacture the solid-state secondary battery No. 201 shown in Figure 2.

[0220] The positive electrode sheet for the solid-state secondary battery used in the manufacture of all-solid-state secondary battery No. 201 was prepared as follows: - Preparation of positive electrode composition - 180 zirconia beads with a diameter of 5 mm were placed in a 45 mL zirconia container (manufactured by Fritsch), and 2.7 g of LPS synthesized in the above synthesis example A, 0.3 g of KYNAR FLEX 2500-20 (trade name, PVdF-HFP: polyvinylidene hexafluoropropylene copolymer, manufactured by Arkema) as solid content, and 22 g of butyl butyrate were added. This container was set in a Fritsch planetary ball mill P-7 (trade name) and stirred at 25°C at a rotation speed of 300 rpm for 60 minutes. After that, LiNi was added as the positive electrode active material. １／３ Co １／３ Mn １／３ O ２ 7.0 g of (NMC) was added, and the container was set in a planetary ball mill P-7 in the same manner, and mixing was continued for 5 minutes at 25°C and a rotation speed of 100 rpm to prepare the positive electrode composition. - Preparation of positive electrode sheet for solid secondary battery - The positive electrode composition obtained above was applied onto a 20 μm thick aluminum foil (positive electrode current collector) using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.), and heated at 100°C for 2 hours to dry the positive electrode composition (remove the dispersion medium). Then, using a heat press machine, the dried positive electrode composition was pressurized at 25°C (10 MPa, 1 min) to prepare a positive electrode sheet for an all-solid-state secondary battery having a positive electrode active material layer with a thickness of 80 μm.

[0221] All-solid-state secondary batteries No. 202 to 215 and c201 to c206 were manufactured in the same manner as all-solid-state secondary batteries No. 201, except that, in the manufacture of all-solid-state secondary battery No. 202, a negative electrode sheet for all-solid-state secondary batteries equipped with a solid electrolyte layer, represented by the No. shown in the "Electrode Active Material Layer (Sheet No.)" column of Table 4, was used instead of negative electrode sheet No. 301 for all-solid-state secondary batteries equipped with a solid electrolyte layer.

[0222] <Evaluation 4: Ionic Conductivity Measurement (Resistance Measurement)> The ionic conductivity of each manufactured all-solid-state secondary battery was measured. Specifically, for each all-solid-state secondary battery, the AC impedance was measured in a constant temperature bath at 25°C using a 1255B FREEQUENCY RESPONSE ANALYZER (product name, manufactured by SOLARTRON) with a voltage amplitude of 5 mV and a frequency of 1 MHz to 1 Hz. From this, the resistance in the thickness direction of the sample for ionic conductivity measurement was determined, and the ionic conductivity was calculated using the following formula (C1). The results are shown in Table 4. Formula (C1): Ionic conductivity σ (mS / cm) = 1000 × Sample layer thickness (cm) / [Resistance (Ω) × Sample area (cm) ２ In equation (C1), the sample layer thickness is the value obtained by measuring the laminate 12 before placing it in the 2032 type coin case 11 and subtracting the thickness of the current collector (total layer thickness of the solid electrolyte layer and electrode active material layer). The sample area is the area of ​​a disc-shaped sheet with a diameter of 14.5 mm. It was determined which of the following evaluation criteria the obtained ionic conductivity σ falls into. In this test, an ionic conductivity σ of evaluation criterion "C" or higher is considered a passing level. - Evaluation Criteria - A: 0.30 ≤ σ B: 0.25 ≤ σ < 0.30 C: 0.20 ≤ σ < 0.25 D: 0.15 ≤ σ < 0.20 E: 0.10 ≤ σ < 0.15 F: σ < 0.10

[0223] <Evaluation 5: High-Potential Cycle Characteristics> For each all-solid-state secondary battery manufactured, the discharge capacity retention rate was measured using the TOSCAT-3000 charge / discharge evaluation device (product name, manufactured by Toyo System Co., Ltd.). Specifically, each all-solid-state secondary battery was subjected to a current density of 0.1 mA / cm² in an environment of 25°C. ２ The battery was charged until the voltage reached 4.5V. After that, the current density was 0.1mA / cm². ２The battery was discharged until the battery voltage reached 2.5V. This one charge and one discharge cycle was considered one charge-discharge cycle, and the same charge-discharge cycle was repeated three times under the same conditions to initialize the battery. After that, the above charge-discharge cycle was repeated, and the discharge capacity of each all-solid-state secondary battery was measured after each charge-discharge cycle using a charge-discharge evaluation device: TOSCAT-3000 (product name). When the discharge capacity of the first charge-discharge cycle after initialization (initial discharge capacity) is set to 100%, the high-potential cycle characteristics were evaluated based on which of the following evaluation criteria the number of charge-discharge cycles at which the discharge capacity retention rate (discharge capacity relative to initial discharge capacity) reached 80% fell into. In this test, the higher the evaluation criterion, the better the high-potential cycle characteristics, and the better the initial battery performance can be maintained even after multiple high-potential charge and discharge cycles (even in long-term use). In this test, an evaluation criterion of "D" or higher is considered a passing level for high-potential cycle characteristics. The results are shown in Table 4. Note that the all-solid-state secondary battery No. The initial discharge capacities of units 101-115 and 201-215 all showed values ​​sufficient for functioning as all-solid-state secondary batteries. - Evaluation Criteria - A: 600 cycles or more B: 450 cycles or more, less than 600 cycles C: 300 cycles or more, less than 450 cycles D: 150 cycles or more, less than 300 cycles E: 80 cycles or more, less than 150 cycles F: 40 cycles or more, less than 80 cycles

[0224] <Evaluation 6: Normal Potential Cycle Characteristics> In the <Evaluation 5: High Potential Cycle Characteristics> test described above, the cycle characteristics at normal potential were evaluated in the same manner as in the "High Potential Cycle Characteristics" test, except that the charging potential was changed to 4.3V. The results are shown in Table 4.

[0225]

[0226] The results shown in Tables 1 to 4 indicate the following: Comparative inorganic solid electrolyte-containing compositions (electrode compositions) that do not contain the polymer binder specified in the present invention are inferior in storage stability, handling properties, and adhesion, and cannot be used to manufacture all-solid-state secondary batteries with low resistance and excellent high-potential cycle characteristics. In contrast, inorganic solid electrolyte-containing compositions (electrode compositions) containing the polymer binder specified in the present invention exhibit excellent dispersion stability and handling properties, even at high concentrations, and enhance the adhesion of solid particles. All-solid-state secondary batteries of the present invention equipped with a solid electrolyte layer or active material layer formed from these compositions exhibit high ionic conductivity (low resistance) and can also achieve excellent high-potential cycle characteristics.

[0227] Although we have described the present invention along with its embodiments, we do not intend to limit our invention in any detail of the description unless specifically designated, and we believe that it should be interpreted broadly without contradicting the spirit and scope of the invention as set forth in the appended claims.

[0228] This application claims priority based on Japanese Patent Application No. 2025-055613, filed in Japan on 28 March 2025, the contents of which are incorporated herein by reference as part of this specification.

[0229] 1. Negative electrode current collector 2. Negative electrode active material layer 3. Solid electrolyte layer 4. Positive electrode active material layer 5. Positive electrode current collector 6. Working part 10. All-solid-state secondary battery 11. 2032 type coin case 12. Laminate for all-solid-state secondary battery 13. Coin-type all-solid-state secondary battery

Claims

1. An inorganic solid electrolyte-containing composition comprising an inorganic solid electrolyte (A) having conductivity of metal ions belonging to Group 1 or Group 2 of the periodic table, a polymer binder (B), and a dispersion medium (C), wherein the polymer forming the polymer binder (B) contains 80% by mass or more of constituent units (D) that satisfy all of the following relationships represented by formulas (1) to (3), and has at least one polar functional group from the following functional group group (a): Formula (1): -8.3 ≤ E ≤ -6.3 Formula (2): 0.2 ≤ σ ≤ 1.2 Formula (3): σ ≤ 1.0 × E + 8.8 In the above formulas, E represents the energy level (eV) of the highest occupied orbital in the constituent unit, and σ represents the maximum value of the positive charge on the carbon atom calculated by Merz-Kollman electrostatic potential fitting in the constituent unit. <Functional group (a)> Sulfonic acid group, phosphate group, phosphonic acid group, hydroxyl group, carboxyl group, dicarboxylic acid group, thiol group, ether group, ester group, amide group, urethane group, urea group, imide group and salts thereof 2. The inorganic solid electrolyte-containing composition according to claim 1, wherein formula (3) is formula (3A): σ ≤ 1.0 × E + 8.

5.

3. The inorganic solid electrolyte-containing composition according to claim 1, wherein formula (3) is the following formula (3B): σ ≤ 1.0 × E + 8.

2.

4. The inorganic solid electrolyte-containing composition according to claim 1, wherein formula (2) is the following formula (2A): 0.4 ≤ σ ≤ 1.

2.

5. The inorganic solid electrolyte-containing composition according to claim 1, wherein the polymer binder (B) is dissolved in the dispersion medium (C).

6. The inorganic solid electrolyte-containing composition according to claim 1, wherein the constituent unit (D) has at least one polar functional group from the functional group group (a).

7. The inorganic solid electrolyte-containing composition according to claim 1, having a constituent unit (A) which has at least one polar functional group from the functional group group (a) and does not satisfy at least one of the relationships represented by formulas (1) to (3).

8. The inorganic solid electrolyte-containing composition according to claim 1, wherein the constituent unit (D) comprises a constituent unit derived from a (meth)acrylamide compound or a constituent unit derived from a maleimide compound.

9. The inorganic solid electrolyte-containing composition according to claim 1, wherein the acid value of the polymer is 0.20 mmol / g or less.

10. The inorganic solid electrolyte-containing composition according to claim 1, wherein the content of the constituent unit (D) is 95% by mass or more.

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

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

13. A sheet for an all-solid-state secondary battery having a layer formed using an inorganic solid electrolyte-containing composition according to any one of claims 1 to 12.

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

15. A method for producing a sheet for an all-solid-state secondary battery, comprising forming a film of an inorganic solid electrolyte-containing composition according to any one of claims 1 to 12.

16. A method for manufacturing an all-solid-state secondary battery, comprising manufacturing an all-solid-state secondary battery via the manufacturing method described in claim 15.

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