Solid electrolyte composition, method for manufacturing solid electrolyte sheet, and method for manufacturing battery

Abstract

A solid electrolyte composition 1000 according to the present disclosure contains a solvent 102 and a solid electrolyte 101 dispersed in the solvent 102. The solid electrolyte 101 includes a halide solid electrolyte. The Hansen solubility parameter polarity term δp of the solvent 102 is greater than 0 and less than 5.9.

Description

[Technical Field]

[0001] The present disclosure relates to a solid electrolyte composition, a method for producing a solid electrolyte sheet, and a method for producing a battery. [Background technology]

[0002] Patent Document 1 discloses a solid electrolyte composition containing a sulfide solid electrolyte and a solvent. The solid electrolyte composition contains a solvent whose polar term Δp of the Hansen solubility parameter (HSP) is 1.6 or more and 5.6 or less. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-102412 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, it is desired to improve the surface smoothness of the solid electrolyte sheet in order to realize a battery with a high energy density. [Means for solving the problem]

[0005] In one embodiment of the present disclosure, the solid electrolyte composition comprises: A solvent; a solid electrolyte dispersed in the solvent; Including, the solid electrolyte includes a halide solid electrolyte, The polar term δp of the Hansen solubility parameter of the solvent is greater than 0 and less than 5.9. [Effects of the Invention]

[0006] The present disclosure can provide a solid electrolyte sheet having high surface smoothness and a battery using the solid electrolyte sheet and having high energy density. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a solid electrolyte composition 1000 according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing how to determine the yield stress. [Figure 3] FIG. 3 is a flowchart showing a method for manufacturing the solid electrolyte sheet 201 in the second embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the electrode 2001 according to the second embodiment. [Figure 5] FIG. 5 is a cross-sectional view of transfer sheet 2002 in the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view of a battery 3000 according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Findings that formed the basis of this disclosure) In the field of conventional secondary batteries, organic electrolytes obtained by dissolving electrolyte salts in organic solvents are mainly used. Secondary batteries using organic electrolytes have concerns about leakage and have also been pointed out as generating large amounts of heat in the event of a short circuit or other problem.

[0009] Meanwhile, all-solid-state secondary batteries, which use inorganic solid electrolytes instead of organic electrolytes, are gaining attention. All-solid-state secondary batteries do not leak. Because of the high thermal stability of inorganic solid electrolytes, they are expected to suppress heat generation in the event of a short circuit.

[0010] Known inorganic solid electrolytes include sulfide solid electrolytes, which contain sulfur as the main component, and oxide solid electrolytes, which contain metal oxides as the main component. However, sulfide solid electrolytes can generate toxic hydrogen sulfide when they react with water. Oxide solid electrolytes have low ionic conductivity. Therefore, the development of new solid electrolytes with high ionic conductivity is desired.

[0011] Halide solid electrolytes are expected to be a new type of solid electrolyte. Halide solid electrolytes are solid electrolytes containing halogen elements. For example, halide solid electrolytes contain lithium, a metal or metalloid element, and at least one halogen element.

[0012] In order to commercialize all-solid-state secondary batteries using solid electrolytes, it is necessary to prepare a solid electrolyte composition having fluidity containing the solid electrolyte. The solid electrolyte composition is applied to the surfaces of electrodes, substrates, etc. to form a solid electrolyte sheet. The solid electrolyte sheet serves as a separator in the battery. To improve the energy density of the battery, it is necessary to thin the solid electrolyte sheet serving as a separator while preventing contact between the positive and negative electrodes.

[0013] To thin the solid electrolyte sheet used in the diaphragm, the solid electrolyte sheet must have sufficient surface smoothness. High surface roughness of the solid electrolyte sheet results in large thickness variations. To reliably prevent contact between the positive and negative electrodes, the solid electrolyte sheet must have a consistent thickness at all positions. Therefore, if large thickness variations are expected, it is difficult to reduce the designed thickness from a safety perspective. Conversely, if the solid electrolyte sheet has excellent surface smoothness and small thickness variations, safety can be ensured even if the designed thickness is reduced. Furthermore, a smooth surface of the solid electrolyte sheet is expected to improve the adhesion between the electrodes and the solid electrolyte sheet, thereby improving battery performance. Therefore, a technology for forming a thin solid electrolyte sheet with excellent surface smoothness is needed.

[0014] To prepare a solid electrolyte composition with fluidity, it is necessary to mix a solid electrolyte with an organic solvent. The inventors prepared solid electrolyte compositions by mixing halide solid electrolytes with various organic solvents, and then fabricated solid electrolyte sheets using these solid electrolyte compositions and investigated their surface smoothness. As a result, it was found that mixing a specific organic solvent with a halide solid electrolyte impairs the fluidity of the solid electrolyte composition and reduces the surface smoothness of the solid electrolyte sheet. For example, an organic solvent suitable for a sulfide solid electrolyte may not be suitable for a halide solid electrolyte. From the above perspective, the configuration of the present disclosure has been conceived.

[0015] (Summary of one aspect of the present disclosure) The solid electrolyte composition according to the first aspect of the present disclosure comprises: A solvent; a solid electrolyte dispersed in the solvent; Including, the solid electrolyte includes a halide solid electrolyte, The polar term δp of the Hansen solubility parameter of the solvent is greater than 0 and less than 5.9.

[0016] When a solid electrolyte sheet is produced using the solid electrolyte composition according to the first embodiment, a solid electrolyte sheet with excellent surface smoothness can be obtained. The solid electrolyte sheet with excellent surface smoothness can improve the energy density of a battery.

[0017] In the second aspect of the present disclosure, for example, in the solid electrolyte composition according to the first aspect, the polar term Δp of the Hansen solubility parameter of the solvent may be 0.6 or more and 5.7 or less.

[0018] When a solid electrolyte sheet is produced using the solid electrolyte composition according to the second embodiment, a solid electrolyte sheet with more excellent surface smoothness can be obtained. A solid electrolyte sheet with excellent surface smoothness can improve the energy density of a battery.

[0019] In a third aspect of the present disclosure, for example, in the solid electrolyte composition according to the first or second aspect, the halide solid electrolyte may contain Li, M1, and X1, where M1 is at least one selected from the group consisting of metal elements and metalloid elements other than Li, and X1 is at least one selected from the group consisting of F, Cl, Br, and I. When the solid electrolyte contains a halide solid electrolyte containing lithium, a lithium secondary battery can be produced using the obtained solid electrolyte sheet.

[0020] In a fourth aspect of the present disclosure, for example, in the solid electrolyte composition according to the third aspect, the halide solid electrolyte may be represented by the following composition formula (1), where α, β, and γ are each independently a value greater than 0. According to the third aspect, the ionic conductivity of the halide solid electrolyte is improved, and therefore the ionic conductivity of a solid electrolyte sheet produced from the solid electrolyte composition can be improved.

[0021] Li α M1 β X1 γ ...Equation (1)

[0022] In a fifth aspect of the present disclosure, for example, in the solid electrolyte composition according to the third or fourth aspect, the M1 may contain yttrium. According to the fourth aspect, the ionic conductivity of the halide solid electrolyte is improved, and therefore the ionic conductivity of a solid electrolyte sheet produced from the solid electrolyte composition can be improved.

[0023] In a sixth aspect of the present disclosure, for example, the solid electrolyte composition according to any one of the first to fifth aspects may further contain a resin binder, which improves the dispersibility of the solid electrolyte in a solvent and the adhesion between particles of the solid electrolyte.

[0024] In a seventh aspect of the present disclosure, for example, in the solid electrolyte composition according to the sixth aspect, the resin binder may contain an elastomer. Elastomers have excellent flexibility and elasticity, and are therefore suitable as resin binders for solid electrolyte sheets.

[0025] In an eighth aspect of the present disclosure, for example, in the solid electrolyte composition according to the seventh aspect, the elastomer may contain a repeating unit derived from styrene. Elastomers containing repeating units derived from styrene are particularly suitable as a resin binder for a solid electrolyte sheet because they have excellent flexibility and elasticity.

[0026] A method for producing a solid electrolyte sheet according to a ninth aspect of the present disclosure includes: Applying the solid electrolyte composition according to any one of the first to eighth aspects to an electrode or a substrate to form a coating film; removing the solvent from the coating film; Includes.

[0027] According to the ninth embodiment, a solid electrolyte sheet having a homogeneous and uniform thickness can be produced.

[0028] A method for manufacturing a battery according to a tenth aspect of the present disclosure includes: A method for manufacturing a battery including a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, comprising: providing a solid electrolyte sheet manufactured by the method according to the ninth aspect; combining the positive electrode and the negative electrode such that the solid electrolyte sheet is disposed between the positive electrode and the negative electrode as the electrolyte layer; Includes.

[0029] According to the tenth embodiment, a battery having a high energy density can be manufactured.

[0030] A solid electrolyte sheet according to an eleventh aspect of the present disclosure includes: a halide solid electrolyte; a resin binder attached to the halide solid electrolyte; Including, The thickness of the solid electrolyte sheet is 1 μm or more and 20 μm or less, The solid electrolyte sheet has a main surface with an arithmetic mean height Sa of 0.37 μm or less.

[0031] The solid electrolyte sheet according to the eleventh embodiment has excellent surface smoothness. A solid electrolyte sheet with excellent surface smoothness can improve the energy density of a battery.

[0032] A battery according to a twelfth aspect of the present disclosure comprises: A positive electrode and a negative electrode; an electrolyte layer disposed between the positive electrode and the negative electrode; Equipped with The electrolyte layer includes a solid electrolyte sheet according to the eleventh embodiment.

[0033] The battery according to the twelfth embodiment can have a high energy density.

[0034] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

[0035] (Embodiment 1) FIG. 1 is a schematic diagram showing a solid electrolyte composition 1000 according to the first embodiment. The solid electrolyte composition 1000 includes a solid electrolyte 101 and a solvent 102. The solid electrolyte 101 is dispersed or dissolved in the solvent 102. The solid electrolyte 101 includes a halide solid electrolyte. In the solvent 102, the polar term Δp of the Hansen solubility parameter (HSP) of the solvent 102 is greater than 0 and less than 5.9.

[0036] When a solid electrolyte sheet is produced using the solid electrolyte composition 1000, a solid electrolyte sheet with excellent surface smoothness can be obtained. A solid electrolyte sheet with excellent surface smoothness can improve the energy density of a battery.

[0037] The solid electrolyte 101 includes a halide solid electrolyte. The halide solid electrolyte includes, for example, Li, M1, and X1. Here, M1 is at least one selected from the group consisting of metal elements and semimetal elements other than Li, and X1 is at least one selected from the group consisting of F, Cl, Br, and I. When the solid electrolyte 101 includes a halide solid electrolyte containing lithium, a lithium secondary battery can be manufactured using the obtained solid electrolyte sheet.

[0038] The present inventors have investigated solid electrolyte compositions containing a solid electrolyte and a solvent. As a result, the present inventors have found that when a halide solid electrolyte is mixed with a solvent having an HSP polarity term δp of 5.9 or more, the fluidity of the solid electrolyte composition is impaired, resulting in a problem of reduced surface smoothness of a solid electrolyte sheet manufactured from the solid electrolyte composition. This problem is thought to arise due to a strong interaction between the halide solid electrolyte and the highly polar solvent. More specifically, the halide solid electrolyte has a highly ionic bonding site such as M1-X1. A solvent having an HSP polarity term δp of 5.9 or more is a solvent with a relatively high charge imbalance. The above problem is thought to be manifested by a strong interaction between the highly ionic bonding site of the halide solid electrolyte and a solvent with a high charge imbalance.

[0039] The present inventors have found that even when a halide solid electrolyte is mixed with a solvent in which the polarity term δp of the HSP is 0, the fluidity of the solid electrolyte composition is impaired, resulting in a problem of reduced surface smoothness of a solid electrolyte sheet produced from the solid electrolyte composition. This problem is thought to be caused by strong interactions between particles of the halide solid electrolyte. More specifically, the halide solid electrolyte has binding sites with high ionic bonding properties, such as M1-X1. A solvent in which the polarity term δp of the HSP is 0 is a solvent in which the charge imbalance is relatively weak. The above problem is thought to become apparent because the strong interactions between particles due to the binding sites with high ionic bonding properties of the halide solid electrolyte cannot be alleviated in a solvent with weak charge imbalance.

[0040] This phenomenon is thought to be unlikely to occur in bonding sites with high covalent bonds, such as the PS bonds found in sulfide solid electrolytes and the MO bonds found in oxide solid electrolytes. In other words, the above issue is thought to be unique to halide solid electrolytes.

[0041] Based on the above findings, the present inventors have further investigated. As a result, they have found that the phenomenon of impairing the fluidity of a solid electrolyte composition containing a halide solid electrolyte can be suppressed by controlling the polarity of the solvent, specifically, by using a solvent whose HSP polarity term δp is greater than 0 and less than 5.9. As described above, in the solid electrolyte composition 1000, the HSP polarity term δp of the solvent 102 is greater than 0 and less than 5.9. This can improve the surface smoothness of a solid electrolyte sheet produced from the solid electrolyte composition 1000.

[0042] The polarity term Δp of the HSP of the solvent 102 may be 0.6 or more and 5.7 or less. This allows a solid electrolyte sheet with superior surface smoothness to be obtained when a solid electrolyte sheet is produced from the solid electrolyte composition 1000. A solid electrolyte sheet with superior surface smoothness can improve the energy density of a battery. The polarity term Δp may be 0.6 or more and 5.0 or less.

[0043] As long as the solid electrolyte has a highly ionic bonding site such as MX, the above-mentioned problems may become apparent. Therefore, the scope of application of the technology of the present disclosure is not limited to a halide solid electrolyte of a specific composition. The technology of the present disclosure can be widely applied to solid electrolyte compositions 1000 containing halide solid electrolytes.

[0044] The "solid electrolyte sheet" may be a self-supporting sheet member, or may be a solid electrolyte layer supported by an electrode or a substrate.

[0045] The solid electrolyte composition 1000 may be a slurry having fluidity. If the solid electrolyte composition 1000 has fluidity, it is possible to form a solid electrolyte sheet by a wet method such as a coating method.

[0046] The solid electrolyte 101 may contain a solid electrolyte other than a halide solid electrolyte, such as a sulfide solid electrolyte or an oxide solid electrolyte. Alternatively, the solid electrolyte 101 may be a halide solid electrolyte. In other words, the solid electrolyte 101 may contain only a halide solid electrolyte.

[0047] The solid electrolyte composition 1000 may further contain a resin binder 103. The resin binder 103 is dispersed or dissolved in a solvent 102. The resin binder 103 can improve the flexibility of the solid electrolyte sheet to be obtained. A solid electrolyte sheet with excellent flexibility easily adheres to electrodes. This can reduce the resistance between the solid electrolyte sheet and the electrodes.

[0048] In the present disclosure, "metalloid elements" are B, Si, Ge, As, Sb and Te.

[0049] In this disclosure, "metal element" refers to all elements in Groups 1 to 12 of the Periodic Table excluding hydrogen, and all elements in Groups 13 to 16 of the Periodic Table excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se.

[0050] In the present disclosure, "metalloid elements" and "metal elements" are a group of elements that can become cations when forming an inorganic compound with a halogen element.

[0051] The solid electrolyte composition 1000 according to the first embodiment will be described in detail below. Hereinafter, the solid electrolyte 101 may be referred to as a "halide solid electrolyte."

[0052] In this disclosure, the term "halide solid electrolyte" refers to a solid electrolyte that contains a halogen element but does not contain sulfur. In this disclosure, the term "sulfur-free solid electrolyte" refers to a solid electrolyte represented by a composition formula that does not contain sulfur. Therefore, a solid electrolyte containing only a trace amount of sulfur, for example, 0.1 mass% or less of sulfur, is classified as a sulfur-free solid electrolyte. The halide solid electrolyte may contain oxygen as an anion other than the halogen element.

[0053] [Solid electrolyte composition] Solid electrolyte composition 1000 in the first embodiment includes halide solid electrolyte 101, solvent 102, and resin binder 103. The halide solid electrolyte 101, solvent 102, and resin binder 103 will be described in detail below.

[0054] <Halide solid electrolyte> The halide solid electrolyte 101 is a material containing Li, M1, and X1. The element M1 and the element X1 are as described above. According to the above configuration, the ionic conductivity of the halide solid electrolyte 101 is further improved, and therefore the ionic conductivity of a solid electrolyte sheet manufactured from the solid electrolyte composition 1000 can be further improved. As a result, when the solid electrolyte sheet is used in a battery, the output characteristics of the battery can be improved. Furthermore, since the halide solid electrolyte 101 has high thermal stability, when the solid electrolyte sheet manufactured from the solid electrolyte composition 1000 is used in a battery, the safety of the battery can be improved. Furthermore, since the halide solid electrolyte 101 does not contain sulfur, the solid electrolyte sheet manufactured from the solid electrolyte composition 1000 can suppress the generation of hydrogen sulfide gas.

[0055] The halide solid electrolyte 101 may be a material represented by the following composition formula (1): In composition formula (1), α, β, and γ are each independently a value greater than 0. γ can be 4 or 6, for example.

[0056] Liα M1 β X1 γ ...Equation (1)

[0057] According to the above configuration, the ionic conductivity of the halide solid electrolyte 101 is improved, which can improve the ionic conductivity of a solid electrolyte sheet produced from the solid electrolyte composition 1000. As a result, when the solid electrolyte sheet is used in a battery, the output characteristics of the battery can be further improved.

[0058] In the above composition formula (1), the element M1 may contain Y (=yttrium). That is, the halide solid electrolyte 101 may contain Y as a metal element.

[0059] The Y-containing halide solid electrolyte 101 may be represented by, for example, the following composition formula (2).

[0060] Li a Me b Y c X6...Formula (2)

[0061] In composition formula (2), a, b, and c may satisfy a+mb+3c=6 and c>0. The element Me is at least one element selected from the group consisting of metal elements and metalloid elements other than Li and Y. m represents the valence of the element Me. When the element Me contains multiple elements, mb is the sum of the values ​​obtained by multiplying the composition ratio of each element by the valence of the element. For example, when Me contains the element Me1 and the element Me2, and the composition ratio of the element Me1 is b1 and the valence of the element Me1 is m1, and the composition ratio of the element Me2 is b2 and the valence of the element Me2 is m2, then mb = m1b1 + m2b2. In composition formula (2), the element X is at least one element selected from the group consisting of F, Cl, Br, and I.

[0062] The element Me may be, for example, at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, Gd, and Nb.

[0063] As the halide solid electrolyte 101, for example, the following materials can be used. According to the following materials, since the ionic conductivity of the halide solid electrolyte 101 is further improved, the ionic conductivity of the solid electrolyte sheet produced from the solid electrolyte composition 1000 in Embodiment 1 can be further improved. Thereby, when the solid electrolyte sheet is used in a battery, the output characteristics of the battery can be further improved.

[0064] The halide solid electrolyte 101 may be a material represented by the following composition formula (A1).

[0065] Li 6-3d Y d X16 ··· Formula (A1)

[0066] In the composition formula (A1), the element X1 is at least one selected from the group consisting of Cl, Br, and I. In the composition formula (A1), d satisfies 0 < d < 2.

[0067] The halide solid electrolyte 101 may be a material represented by the following composition formula (A2).

[0068] Li3YX16 ··· Formula (A2)

[0069] In the composition formula (A2), the element X1 is at least one selected from the group consisting of Cl, Br, and I.

[0070] The halide solid electrolyte 101 may be a material represented by the following composition formula (A3).

[0071] Li 3-3δ Y 1+δ Cl6 ··· Formula (A3)

[0072] In the composition formula (A3), δ satisfies 0 < δ ≤ 0.15.

[0073] The halide solid electrolyte 101 may be a material represented by the following composition formula (A4).

[0074] Li 3-3δ Y 1+δ Br6...Formula (A4)

[0075] In the composition formula (A4), δ satisfies the relationship 0<δ≦0.25.

[0076] The halide solid electrolyte 101 may be a material represented by the following composition formula (A5).

[0077] Li 3-3δ+a Y 1+δ-a Me a Cl 6-x-y Br x I y ...Formula (A5)

[0078] In the composition formula (A5), the element Me is at least one element selected from the group consisting of Mg, Ca, Sr, Ba, and Zn.

[0079] In addition, the composition formula (A5) is -1<δ<2, 0 <a<3、 0<(3-3δ+a), 0<(1+δ-a), 0≦x≦6, 0 ≤ y ≤ 6, and (x+y)≦6, Meet the following.

[0080] The halide solid electrolyte 101 may be a material represented by the following composition formula (A6).

[0081] Li 3-3δ Y 1+δ-a Me a Cl 6-x-y Br x I y ...Formula (A6)

[0082] In the composition formula (A6), the element Me is at least one element selected from the group consisting of Al, Sc, Ga, and Bi.

[0083] In addition, the composition formula (A6) is -1<δ<1, 0 <a<2、 0<(1+δ-a), 0≦x≦6, 0 ≤ y ≤ 6, and (x+y)≦6, Meet the following.

[0084] The halide solid electrolyte 101 may be a material represented by the following composition formula (A7).

[0085] Li 3-3δ-a Y 1+δ-a Me a Cl 6-x-y Br x I y ...Formula (A7)

[0086] In the composition formula (A7), the element Me is at least one element selected from the group consisting of Zr, Hf, and Ti.

[0087] In addition, the above composition formula (A7) is -1<δ<1, 0 <a<1.5、 0<(3-3δ-a), 0<(1+δ-a), 0≦x≦6, 0 ≤ y ≤ 6, and (x+y)≦6, Meet the following.

[0088] The halide solid electrolyte 101 may be a material represented by the following composition formula (A8).

[0089] Li 3-3δ-2a Y 1+δ-a Me a Cl 6-x-y Br x I y ...Formula (A8)

[0090] In the compositional formula (A8), the element Me is at least one selected from the group consisting of Ta and Nb.

[0091] Also, the above compositional formula (A8) is -1 < δ < 1, 0 < a < 1.2, 0 < (3 - 3δ - 2a), 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, and (x + y) ≤ 6, and satisfies.

[0092] The halide solid electrolyte may be a compound containing Li, M2, O (oxygen), and X2. The element M2 includes at least one selected from the group consisting of, for example, Nb and Ta. Also, X2 is at least one selected from the group consisting of F, Cl, Br, and I.

[0093] The compound containing Li, M2, X2, and O (oxygen) may be represented by, for example, the compositional formula: Li x M2O y X2 5+x―2y Here, x may satisfy 0.1 < x < 7.0. y may satisfy 0.4 < y < 1.9.

[0094] As the halide solid electrolyte 101, more specifically, for example, Li3YX36, Li2MgX34, Li2FeX34, Li(Al,Ga,In)X34, Li3(Al,Ga,In)X3 6、 Li3(Ca,Y,Gd)X36, Li3(Ti,Al)X36, Li 2.7(Ti,Al)X36, LiTaOCl4, etc. can be used. Here, in these materials, the element X3 is at least one selected from the group consisting of F, Cl, Br, and I. In this disclosure, when an element in a formula is expressed as "(Al,Ga,In)", this notation indicates at least one element selected from the group of elements in parentheses. In other words, "(Al,Ga,In)" is synonymous with "at least one selected from the group consisting of Al, Ga, and In." The same applies to other elements.

[0095] The shape of the halide solid electrolyte 101 is not particularly limited and may be, for example, needle-like, spherical, oval-spherical, etc. For example, the shape of the halide solid electrolyte 101 may be particulate.

[0096] When the halide solid electrolyte 101 is particulate (for example, spherical), the particle diameter (median diameter) of the solid electrolyte may be 1 μm or more and 100 μm or less, or 1 μm or more and 10 μm or less. When the particle diameter of the halide solid electrolyte 101 is 1 μm or more and 100 μm or less, the halide solid electrolyte 101 can be easily dispersed in the solvent 102.

[0097] When the halide solid electrolyte 101 is particulate (e.g., spherical), the particle diameter of the solid electrolyte may be 0.1 μm or more and 1 μm or less. When the particle diameter of the halide solid electrolyte 101 is 0.1 μm or more and 1 μm or less, the solid electrolyte sheet produced from the solid electrolyte composition 1000 can have higher surface smoothness and a denser structure.

[0098] The median diameter refers to the particle diameter at which the cumulative volume in the volume-based particle size distribution is 50%. The volume-based particle size distribution is determined, for example, by a laser diffraction scattering method. The same applies to the other materials described below.

[0099] Next, a description will be given of a method for producing the halide solid electrolyte 101. Here, a method for producing the halide solid electrolyte represented by the above composition formula (1) will be exemplified.

[0100] First, multiple types of binary halide raw material powders are prepared depending on the desired composition. A binary halide is a compound consisting of two elements, including a halogen element. For example, to produce Li3YCl6, raw material powders LiCl and YCl3 are prepared in a molar ratio of 3:1. By selecting the type of raw material powder, the elemental species of "M" and "X" in composition formula (1) can be determined. In addition, the values ​​of "α," "β," and "γ" in composition formula (1) can be adjusted by adjusting the type of raw material powder, the raw material powder blending ratio, and the synthesis process.

[0101] After mixing and pulverizing the raw material powders, the raw material powders are reacted with each other using a mechanochemical milling method. Alternatively, after mixing and pulverizing the raw material powders, the mixture may be fired in a vacuum or in an inert atmosphere. For example, firing may be performed at a temperature between 100°C and 550°C for one hour or more. By these methods, a halide solid electrolyte represented by the above composition formula (1) can be obtained.

[0102] <Solvent> The solvent 102 may have an HSP polarity term δp of 0.6 or more and 5.7 or less. When the polarity term δp is 5.7 or less, good fluidity of the solid electrolyte composition 1000 can be achieved, and the surface smoothness of the solid electrolyte sheet produced from the solid electrolyte composition 1000 can be improved. When the polarity term δp is 0.6 or more, good dispersibility of the solid electrolyte 101 can be achieved, and the surface smoothness of the solid electrolyte sheet produced from the solid electrolyte composition 1000 can be further improved.

[0103] The Hansen Solubility Parameter (HSP) is a method for defining the solubility parameters of a solvent. The HSP consists of a dispersion term δd, a polar term δp, and a hydrogen bonding term δh. The polar term δp is a parameter correlated with the dielectric constant and dipole moment of the solvent, and therefore indicates the degree of charge imbalance. HSP databases have been constructed, and the HSP value of a solvent can be obtained by referencing the database built into software such as Hansen Solubility Parameters in Practice (HSPiP). The HSP of a mixed solvent containing multiple solvents can be calculated by summing the values ​​obtained by multiplying the HSP of each solvent by the volumetric concentration of each solvent.

[0104] The solvent 102 may be an organic solvent, which is a compound containing carbon, such as carbon, hydrogen, nitrogen, oxygen, sulfur, or a halogen.

[0105] The solvent 102 may contain at least one selected from the group consisting of hydrocarbons, compounds having a halogen group, and compounds having an ether bond.

[0106] A hydrocarbon is a compound consisting only of carbon and hydrogen. The hydrocarbon may be an aliphatic hydrocarbon. The hydrocarbon may be a saturated hydrocarbon or an unsaturated hydrocarbon. The hydrocarbon may be linear or branched. The number of carbon atoms contained in the hydrocarbon is not particularly limited and may be 7 or more. By using a hydrocarbon, a solid electrolyte composition 1000 having excellent dispersibility of the solid electrolyte 101 can be obtained. Furthermore, a decrease in the ionic conductivity of the solid electrolyte 101 due to mixing with the solvent 102 can be suppressed.

[0107] The hydrocarbon may have a ring structure. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be a monocyclic or a polycyclic hydrocarbon. When the hydrocarbon has a ring structure, the halide solid electrolyte 101 can be easily dispersed in the solvent 102. From the viewpoint of improving the dispersibility of the halide solid electrolyte 101 in the solid electrolyte composition 1000, the hydrocarbon may contain an aromatic hydrocarbon. The hydrocarbon may be an aromatic hydrocarbon.

[0108] The compound having a halogen group may be composed only of carbon and hydrogen in the portion other than the halogen group. In other words, the compound having a halogen group refers to a compound in which at least one hydrogen atom contained in a hydrocarbon is substituted with a halogen group. Examples of the halogen group include F, Cl, Br, and I. The halogen group may be at least one selected from the group consisting of F, Cl, Br, and I. The compound having a halogen group may have high polarity. By using a compound having a halogen group in the solvent 102, the halide solid electrolyte 101 can be easily dispersed in the solvent 102, thereby obtaining a solid electrolyte composition 1000 with excellent dispersibility. As a result, the solid electrolyte sheet produced from the solid electrolyte composition 1000 can have excellent ionic conductivity and a denser structure.

[0109] The number of carbon atoms contained in the compound having a halogen group is not particularly limited and may be 7 or more. This makes the compound having a halogen group less likely to volatilize, allowing the solid electrolyte composition 1000 to be produced stably. Furthermore, the compound having a halogen group may have a large molecular weight. That is, the compound having a halogen group may have a high boiling point.

[0110] The compound having a halogen group may have a ring structure. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be a monocyclic or a polycyclic. When the compound having a halogen group has a ring structure, the halide solid electrolyte 101 can be easily dispersed in the solvent 102. From the viewpoint of improving the dispersibility of the halide solid electrolyte 101 in the solid electrolyte composition 1000, the compound having a halogen group may contain an aromatic hydrocarbon. The compound having a halogen group may be an aromatic hydrocarbon.

[0111] The compound having a halogen group may have only a halogen group as a functional group. In this case, the number of halogens contained in the compound having a halogen group is not particularly limited. At least one selected from the group consisting of F, Cl, Br, and I may be used as the halogen group. By using such a compound in the solvent 102, the halide solid electrolyte 101 can be easily dispersed in the solvent 102, thereby obtaining a solid electrolyte composition 1000 with excellent dispersibility. As a result, the solid electrolyte sheet produced from the solid electrolyte composition 1000 can have excellent ionic conductivity and a denser structure. By using such a compound in the solvent 102, the solid electrolyte sheet produced from the solid electrolyte composition 1000 can easily have a denser structure with fewer pinholes, irregularities, etc.

[0112] The compound having a halogen group may be a halogenated hydrocarbon. A halogenated hydrocarbon refers to a compound in which all hydrogen atoms contained in a hydrocarbon are substituted with halogen groups. By using a halogenated hydrocarbon as the solvent 102, the halide solid electrolyte 101 can be easily dispersed in the solvent 102, thereby obtaining a solid electrolyte composition 1000 with excellent dispersibility. As a result, a solid electrolyte sheet produced from the solid electrolyte composition 1000 can have excellent ionic conductivity and a denser structure. By using such a compound as the solvent 102, a solid electrolyte sheet produced from the solid electrolyte composition 1000 can easily have a denser structure with fewer pinholes, irregularities, and the like.

[0113] The compound having an ether bond may be composed only of carbon and hydrogen in the portion other than the ether bond. In other words, a compound having an ether bond refers to a compound in which at least one C-C bond contained in a hydrocarbon is replaced with a C-O-C bond. A compound having an ether bond may have high polarity. By using a compound having an ether bond as the solvent 102, the halide solid electrolyte 101 can be easily dispersed in the solvent 102. Therefore, a solid electrolyte composition 1000 with excellent dispersibility can be obtained. As a result, a solid electrolyte sheet manufactured from the solid electrolyte composition 1000 can have excellent ionic conductivity and a denser structure.

[0114] The compound having an ether bond may have a ring structure. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be a monocyclic or a polycyclic. When the compound having an ether bond has a ring structure, the halide solid electrolyte 101 can be easily dispersed in the solvent 102. From the viewpoint of improving the dispersibility of the halide solid electrolyte 101 in the solid electrolyte composition, the compound having an ether bond may contain an aromatic hydrocarbon. The compound having an ether bond may be an aromatic hydrocarbon.

[0115] Examples of the solvent 102 include ethylbenzene (δp=0.6), mesitylene (δp=0.6), pseudocumene (δp=1.0), o-xylene (δp=1.0), p-xylene (1.0), cumene (δp=1.2), toluene (δp=1.4), tetralin (δp=2.0), m-xylene (δp=2.6), dibutyl ether (δp=3.4), and 1,2,4-trichlorobenzene (δp=4.2). , chlorobenzene (δp=4.3), 2,4-dichlorotoluene (δp=4.3), anisole (δp=4.4), o-chlorotoluene (δp=4.9), m-dichlorobenzene (δp=5.1), p-chlorotoluene (δp=6.2), o-dichlorobenzene (δp=6.3), 1,4-dichlorobutane (δp=7.7), and 3,4-dichlorotoluene (δp=9.8). These may be used alone or in combination of two or more.

[0116] From the viewpoint of cost, commercially available xylene (mixed xylene) may be used as the solvent 102. For example, mixed xylene (Δp=1.6) in which o-xylene, m-xylene, p-xylene, and ethylbenzene are mixed in a mass ratio of 24:42:18:16 may be used.

[0117] The boiling point of the solvent 102 may be 100°C or higher and 250°C or lower. The solvent 102 may be liquid at room temperature (25°C). Such a solvent is less likely to volatilize at room temperature, allowing the solid electrolyte composition 1000 to be stably produced. Therefore, the solid electrolyte composition 1000 can be easily applied to the surface of an electrode or a substrate. Furthermore, the solvent 102 contained in the solid electrolyte composition 1000 can be easily removed by drying, which will be described later.

[0118] The water content of the solvent 102 may be 10 ppm by mass or less. Reducing the water content can suppress a decrease in ionic conductivity due to a reaction of the solid electrolyte 101. Methods for reducing the water content include a dehydration method using a molecular sieve and a dehydration method using bubbling with an inert gas such as nitrogen gas or argon gas. A dehydration method using bubbling with an inert gas is recommended from the viewpoint of being able to remove oxygen and water at the same time. The water content can be measured using a Karl Fischer water content analyzer.

[0119] The solvent 102 may be a liquid capable of dispersing the halide solid electrolyte 101. The halide solid electrolyte 101 does not have to be dissolved in the solvent 102. By not dissolving the halide solid electrolyte 101, it is possible to prepare a solid electrolyte composition 1000 in a state in which the ion-conducting phase formed during the production of the halide solid electrolyte 101 is maintained. Therefore, a decrease in the ion conductivity of a solid electrolyte sheet produced using the solid electrolyte composition 1000 can be suppressed.

[0120] The solvent 102 may partially or completely dissolve the halide solid electrolyte 101. Dissolving the halide solid electrolyte 101 can improve the density of a solid electrolyte sheet produced using the solid electrolyte composition 1000.

[0121] The polarity term δp of the HSP of the solvent 102 contained in the solid electrolyte composition 1000 may be determined by a chemical analysis method. For example, the composition and structure of the solvent 102 can be determined by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), mass spectrometry (MS), or elemental analysis, and the polarity term δp of the HSP can be determined. In addition, for a solid electrolyte sheet produced from the solid electrolyte composition 1000, the polarity term δp of the solid electrolyte composition 1000 used in the production can be determined by analyzing the remaining solvent by the above method.

[0122] <Resin binder> The solid electrolyte composition 1000 may contain a resin binder 103 for the purpose of improving the dispersibility of the solid electrolyte 101 in the solvent 102 and the adhesion between particles of the solid electrolyte 101. Examples of the resin binder 103 include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl ester of acrylic acid, polyethyl ester of acrylic acid, hexyl ester of polyacrylic acid, polymethacrylic acid, polymethyl ester of methacrylic acid, polyethyl ester of methacrylic acid, hexyl ester of polymethacrylic acid, polyvinyl acetate, polyvinylpyrrolidone, polyether, polycarbonate, polyethersulfone, polyetherketone, polyetheretherketone, polyphenylene sulfide, hexafluoropolypropylene, styrene-butadiene rubber, carboxymethyl cellulose, and ethyl cellulose. Furthermore, a copolymer containing two or more monomers selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, butadiene, styrene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid ester, acrylic acid, and hexadiene can also be used as the resin binder 103. These may be used alone or in combination of two or more.

[0123] The binder 103 may contain an elastomer from the viewpoint of excellent binding properties. An elastomer refers to a polymer having rubber elasticity. The elastomer used as the binder 103 may be a thermoplastic elastomer or a thermosetting elastomer. The binder 103 may contain a thermoplastic elastomer. Examples of elastomers include styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS), butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), styrene-butylene rubber (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated isoprene rubber (HIR), hydrogenated butyl rubber (HIIR), hydrogenated nitrile rubber (HNBR), hydrogenated styrene-butylene rubber (HSBR), etc. A mixture containing two or more selected from these may be used as the binder 103.

[0124] The elastomer contained in the binder 103 may contain a repeating unit derived from styrene. The repeating unit refers to a molecular structure derived from a monomer and is sometimes called a constituent unit. In this disclosure, an elastomer containing a repeating unit derived from styrene may be called a styrene-based elastomer. Styrene-based elastomers are more flexible and elastic, making them suitable as binders for solid electrolyte sheets.

[0125] Examples of styrene-based elastomers include styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS), styrene-butylene rubber (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-butylene rubber (HSBR). The binder 103 may contain SBR or SEBS as the styrene-based elastomer. A mixture containing two or more selected from these may also be used as the binder 103. Because styrene-based elastomers are flexible, the binder 103 containing a styrene-based elastomer can impart flexibility to a solid electrolyte sheet manufactured from the solid electrolyte composition 1000. As a result, the electrolyte layer of a battery using the solid electrolyte sheet can be made thinner, thereby further improving the energy density of the battery.

[0126] The resin binder 103 may contain a modified group. The modified group is a functional group that chemically modifies all of the repeating units of the polymer chain, some of the repeating units of the polymer chain, or the end of the polymer chain through substitution, addition, or the like. Examples of the modified group include functional groups containing elements such as O or N, which have relatively high electronegativity, or Si, which has relatively low electronegativity. The inclusion of such a functional group in the resin binder 103 can impart polarity to the resin binder 103. Examples of the modified group include a carboxylic acid group, a maleic anhydride group, an acyl group, a hydroxy group, a sulfo group, a sulfanyl group, a phosphate group, a phosphonate group, an isocyanate group, an epoxy group, a silyl group, an amino group, a nitrile group, and a nitro group. When the resin binder 103 contains a modified group, the dispersibility of the solid electrolyte 101 contained in the solid electrolyte composition 1000 can be further improved. The binder 103 may contain SBR into which a modified group has been introduced.

[0127] The weight average molecular weight (Mw ) may be, for example, 1,000 or more and 1,000,000 or less, or 10,000 or more and 500,000 or less. When the weight-average molecular weight of the polymer contained in the binder 103 is 1,000 or more, the particles of the solid electrolyte 101 can be bonded to each other with sufficient adhesive strength. When the weight-average molecular weight of the polymer contained in the binder 103 is 1,000,000 or less, the binder 103 is less likely to inhibit ion conduction between the particles of the solid electrolyte 101, thereby improving the charge / discharge characteristics of the battery. The weight-average molecular weight of the polymer contained in the binder 103 can be determined, for example, by gel permeation chromatography (GPC) measurement using polystyrene as a standard sample. In other words, the weight-average molecular weight is a value converted into polystyrene. In the GPC measurement, chloroform may be used as an eluent.

[0128] The ratio of the mass of the binder 103 to the mass of the solid electrolyte 101 is, for example, 0.5% by mass, and may be 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, or 8% by mass or more. The upper limit of the ratio of the mass of the binder 103 to the mass of the solid electrolyte 101 is, for example, 10% by mass.

[0129] The solid electrolyte composition 1000 may be in the form of a paste or a dispersion liquid. The solid electrolyte 101 is, for example, particles. In the solid electrolyte composition 1000, the particles of the solid electrolyte 101 are mixed with a solvent 102. The method for mixing the solid electrolyte 101, the solvent 102, and the resin binder 103 in producing the solid electrolyte composition 1000 is not particularly limited. Examples of the method include mixing methods using a mixing device such as a stirring type, a shaking type, or a rotating type. Examples of the method include mixing methods using a dispersion kneading device such as a high-speed homogenizer, a thin film rotary high-speed mixer, an ultrasonic homogenizer, a ball mill, a bead mill, a planetary mixer, a sand mill, a roll mill, or a kneader. These mixing methods may be used alone or in combination of two or more.

[0130] The solid electrolyte composition 1000 is produced, for example, by the following method. First, the solid electrolyte 101 and the solvent 102 are mixed, and then wet-pulverized and dispersed using a ball mill or a bead mill. This process allows the solid electrolyte 101 to be finely divided into particles with a particle diameter of 1 μm or less, and the solid electrolyte 101 to be uniformly dispersed in the solvent 102. Next, the obtained dispersion is dispersed by shear using a homogenizer or a high-speed shear mixer, while a resin binder solution is added to prepare the solid electrolyte composition 1000. This process allows the fine particles of the solid electrolyte 101 to be dispersed and stabilized in the solvent 102, and a solid electrolyte composition 1000 with excellent fluidity can be produced.

[0131] The resin binder solution is a solution containing a resin binder 103 and a solvent 102. The composition of the solvent contained in the resin binder solution may be the same as or different from the composition of the solvent contained in the dispersion of the solid electrolyte 101.

[0132] The solid content concentration of the solid electrolyte composition 1000 is determined appropriately depending on the particle size of the solid electrolyte 101, the type of solvent 102, and the type of resin binder 103. The solid content concentration may be 10% by mass or more and 60% by mass or less, or 20% by mass or more and 40% by mass or less. By setting the solid content concentration to 20% by mass or more, the viscosity of the solid electrolyte composition 1000 can be increased, and sagging of the solid electrolyte composition 1000 when applied to a substrate can be suppressed. By setting the solid content concentration to 40% by mass or less, the wet film thickness when the solid electrolyte composition 1000 is applied to a substrate to form a coating film can be increased, and a solid electrolyte sheet with a more uniform film thickness can be produced.

[0133] The rheology of the solid electrolyte composition 1000 can be quantified as the viscosity, yield stress, storage modulus G', and loss tangent tanδ using a viscosity / viscoelasticity measuring device. The viscosity, yield stress, storage modulus, and loss tangent of the solid electrolyte composition 1000 can be adjusted by controlling the solid electrolyte 101, solvent 102, resin binder 103, the composition ratio of each component, solid content concentration, and production method.

[0134] The viscosity of the solid electrolyte composition 1000, measured using a viscosity / viscoelasticity measuring device at 25°C and a shear rate of 1 / s, may be 1 Pa·s or more and 15 Pa·s or less. By setting the viscosity to 1 Pa·s or more, sagging when applying the solid electrolyte composition 1000 to a substrate can be suppressed. By setting the viscosity to 15 Pa·s or less, a coating film with a more uniform thickness can be produced. The viscosity, measured at 25°C and a shear rate of 1 / s, may be 2.4 Pa·s or more and 16.3 Pa·s or less.

[0135] The solid electrolyte composition 1000 may have a viscosity of 10 mPa·s or more measured at 25°C and a shear rate of 1000 / s using a viscosity / viscoelasticity measuring device. By setting the viscosity to 10 mPa·s or more, the affinity between the solid electrolyte 101 and the solvent 102 can be increased. As a result, separation between the solid electrolyte 101 and the solvent 102 is suppressed, and the solid electrolyte composition 1000 can be efficiently delivered and applied. The viscosity measured at 25°C and a shear rate of 1000 / s may be 21.6 mPa·s or more.

[0136] Ideally, the viscosity measured at a low shear rate of 1 / s is not too high, and the viscosity measured at a high shear rate of 1000 / s is not too low. Therefore, the viscosity range may be defined by combining the upper limit of the viscosity measured at a low shear rate of 1 / s and the lower limit of the viscosity measured at a high shear rate of 1000 / s.

[0137] The solid electrolyte composition 1000 may have a yield stress of 25 Pa or less, as measured at 25°C using a viscosity / viscoelasticity measuring device. By setting the yield stress to 25 Pa or less, a more uniform coating film can be produced. The yield stress may be 3.8 Pa or more and 22.0 Pa or less.

[0138] Figure 2 shows how to determine the yield stress. The amount of strain on the vertical axis is measured while controlling the shear stress on the horizontal axis. The intersection of the tangent line of the low-strain elastic deformation region and the tangent line of the high-strain plastic deformation region represents the yield stress.

[0139] The solid electrolyte composition 1000 may have a storage modulus G' of 1 Pa or more and 40 Pa or less, measured using a viscosity / viscoelasticity measuring device at 25°C, a frequency of 1 Hz, and a strain of 10% to 25%. The loss tangent tanδ measured under the same conditions may be 0.8 or more and 3.0 or less. By adjusting at least one of the storage modulus G' and the loss tangent tanδ to fall within the above ranges, the solid electrolyte composition 1000 can have good fluidity. This allows for the production of a more uniform coating film. The storage modulus G' may be 2.5 Pa or more and 32.4 Pa or less, and the loss tangent tanδ may be 0.80 or more and 2.99 or less.

[0140] (Embodiment 2) The following describes the second embodiment. Explanations that overlap with the first embodiment will be omitted where appropriate.

[0141] A method for manufacturing a solid electrolyte sheet will now be described with reference to Fig. 3. Fig. 3 is a flowchart showing the method for manufacturing a solid electrolyte sheet.

[0142] The method for manufacturing a solid electrolyte sheet may include steps S01, S02, and S03. Step S01 in FIG. 3 has been described in the first embodiment. The method for manufacturing a solid electrolyte sheet includes step S02 of applying solid electrolyte composition 1000 of the first embodiment and step S03 of drying. Steps S01, S02, and S03 may be performed in this order. Through these steps, a solid electrolyte sheet 201 with excellent surface smoothness can be manufactured using solid electrolyte composition 1000 of the first embodiment.

[0143] 4 is a cross-sectional view of electrode 2001 in embodiment 2. Electrode 2001 can be manufactured by including a step of applying solid electrolyte composition 1000 onto electrode 202 as step S02.

[0144] 5 is a cross-sectional view of transfer sheet 2002 in embodiment 2. Transfer sheet 2002 can be manufactured by including a step of applying solid electrolyte composition 1000 onto substrate 203 as step S02.

[0145] In step S02, the solid electrolyte composition 1000 is applied onto the electrode 202 or the substrate 203. As a result, a coating film of the solid electrolyte composition 1000 is formed on the electrode 202 or the substrate 203.

[0146] The electrode 202 may be a positive electrode or a negative electrode, or may be a member obtained by applying a solid electrolyte onto a positive electrode or a negative electrode. The positive electrode or negative electrode includes a current collector and an active material layer disposed on the current collector. By applying the solid electrolyte composition 1000 onto the electrode 202 and then performing step S03 described below, an electrode 2001 consisting of a laminate of the electrode 202 and the solid electrolyte sheet 201 is produced.

[0147] Materials used for the substrate 203 include metal foils and resin films. Materials for the metal foil include copper (Cu), aluminum (Al), iron (Fe), nickel (Ni), and alloys thereof. Materials for the resin film include polyethylene terephthalate (PET), polyimide (PI), and polytetrafluoroethylene (PTFE). By applying the solid electrolyte composition 1000 onto the substrate 203 and then performing step S03, which will be described later, a transfer sheet 2002 consisting of a laminate of the substrate 203 and the solid electrolyte sheet 201 is produced.

[0148] Examples of the coating method include die coating, gravure coating, doctor blade coating, bar coating, spray coating, electrostatic coating, etc. From the viewpoint of mass productivity, the die coating method may be used for coating.

[0149] In step S03, the solid electrolyte composition 1000 applied onto the substrate 203 is dried. By drying the solid electrolyte composition 1000, for example, the solvent 102 is removed from the applied film of the solid electrolyte composition 1000, and a solid electrolyte sheet is produced.

[0150] Examples of a drying method for removing the solvent 102 from the solid electrolyte composition 1000 include warm air / hot air drying, infrared heating drying, reduced pressure drying, vacuum drying, high frequency dielectric heating drying, and high frequency induction heating drying. These methods may be used alone or in combination of two or more.

[0151] The solvent 102 may be removed from the solid electrolyte composition 1000 by drying under reduced pressure. That is, the solvent 102 may be removed from the solid electrolyte composition 1000 in a pressure atmosphere lower than atmospheric pressure. The pressure atmosphere lower than atmospheric pressure may be, for example, −0.01 MPa or lower in gauge pressure. The drying under reduced pressure may be performed at a temperature of 50° C. or higher and 250° C. or lower.

[0152] The solvent 102 may be removed from the solid electrolyte composition 1000 by vacuum drying. That is, the solvent 102 may be removed from the solid electrolyte composition 1000 at a temperature lower than the boiling point of the solvent 102 and in an atmosphere at or below the equilibrium vapor pressure of the solvent 102.

[0153] From the viewpoint of production costs, the solvent 102 may be removed from the solid electrolyte composition 1000 by hot air drying. The set temperature of the hot air may be 50°C or higher and 250°C or lower, or 80°C or higher and 150°C or lower.

[0154] The removal of the solvent 102 can be confirmed by, for example, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), gas chromatography (GC), or gas chromatography mass spectrometry (GC / MS). It is sufficient that the dried solid electrolyte sheet 201 has ion conductivity, and the solvent 102 does not have to be completely removed. A portion of the solvent 102 may remain on the solid electrolyte sheet 201.

[0155] The ionic conductivity of the solid electrolyte sheet 201 may be 0.1 mS / cm or more. By increasing the ionic conductivity to 0.1 mS / cm or more, the output characteristics of the battery can be improved. In order to improve the ionic conductivity of the solid electrolyte sheet 201, the sheet may be pressure-molded using a press or the like.

[0156] (Embodiment 3) The following describes the third embodiment. Explanations that overlap with the first or second embodiment will be omitted as appropriate.

[0157] FIG. 6 is a cross-sectional view of a battery 3000 according to the third embodiment.

[0158] The battery 3000 in the third embodiment includes a positive electrode 301 , a negative electrode 303 , and an electrolyte layer 302 .

[0159] The electrolyte layer 302 is disposed between the positive electrode 301 and the negative electrode 303 .

[0160] The electrolyte layer 302 includes the solid electrolyte sheet 201 of the second embodiment.

[0161] The battery 3000 includes a solid electrolyte sheet 201 with excellent surface smoothness. A smooth surface of the solid electrolyte sheet 201 means that the thickness of the solid electrolyte sheet 201 has little variation. A solid electrolyte sheet 201 with little variation in thickness can have a thickness close to the design value at all positions within its surface. Therefore, even if the electrolyte layer 302 is made thinner, the possibility of contact (short circuit) between the positive electrode 301 and the negative electrode 303 can be reduced, and the energy density can be improved. Furthermore, the safety of the battery 3000 can be improved by including a solid electrolyte sheet 201 containing a solid electrolyte 101 with high thermal stability.

[0162] Battery 3000 can be manufactured, for example, by combining electrode 2001 in embodiment 2 with an electrode having a polarity opposite to that of electrode 2001. This method is advantageous in terms of reducing the number of parts. When electrode 2001 is a positive electrode, the electrode having a polarity opposite to that of electrode 2001 is a negative electrode. When electrode 2001 is a negative electrode, the electrode having a polarity opposite to that of electrode 2001 is a positive electrode. The positive electrode or negative electrode includes a current collector and an active material layer disposed on the current collector. A layer containing a solid electrolyte may be provided on the active material layer of the positive electrode or the active material layer of the negative electrode.

[0163] The battery 3000 may be manufactured using the transfer sheet 2002 in the second embodiment. That is, the battery 3000 may be manufactured by transferring the solid electrolyte sheet 201 from the transfer sheet 2002 to the first electrode and combining the first electrode and the second electrode so that the transferred solid electrolyte sheet 201 is disposed between the first electrode and the second electrode. To transfer the solid electrolyte sheet 201 from the transfer sheet 2002 to the first electrode, the transfer sheet is placed on the first electrode so that the solid electrolyte sheet 201 and the first electrode are in contact with each other, and then the base material 203 is removed. This results in the solid electrolyte sheet 201 being transferred to the first electrode. When the first electrode is a positive electrode, the second electrode is a negative electrode. When the first electrode is a negative electrode, the second electrode is a positive electrode. The positive electrode and the negative electrode each include a current collector and an active material layer disposed on the current collector. A layer containing a solid electrolyte may be provided on the active material layer of the positive electrode or the active material layer of the negative electrode.

[0164] According to the method using the transfer sheet 2002, the solid electrolyte sheet 201 is produced in a separate process from the positive and negative electrodes, so there is no need to consider the effect of the solvent used in producing the solid electrolyte sheet 201 on the positive or negative electrodes, which increases the range of solvent options.

[0165] The electrolyte layer 302 is a layer containing an electrolyte material. The electrolyte material is, for example, a solid electrolyte. That is, the electrolyte layer 302 may be a solid electrolyte layer. Examples of the solid electrolyte contained in the electrolyte layer 302 include a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte. The solid electrolyte may be, for example, a halide solid electrolyte.

[0166] In the present disclosure, the term "oxide solid electrolyte" refers to a solid electrolyte containing oxygen. Here, the oxide solid electrolyte may further contain anions other than sulfur and halogen elements as anions other than oxygen.

[0167] The "halide solid electrolyte" is as described in the first embodiment, and corresponds to the solid electrolyte 101 contained in the solid electrolyte composition 1000 in the first embodiment.

[0168] Sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, and Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 These can be used in addition to LiX, Li2O, MO q , and / or Li p MO q The element X in "LiX" is at least one element selected from the group consisting of F, Cl, Br, and I. q " and "Li p MO q "The element M is at least one element selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. q " and "Li p MO q " p and q in this expression are independent natural numbers.

[0169] Oxide solid electrolytes include NASICON-type solid electrolytes, such as LiTi2(PO4)3 and its elemental substitution products, (LaLi)TiO3-based perovskite-type solid electrolytes, and Li 14 ZnGeO 16 , Li4SiO4, LiGeO4 and their element-substituted LISICON-type solid electrolytes, Li7La3Zr2O 12 Garnet-type solid electrolytes, such as those substituted with these elements, Li3PO4 and its N-substituted compounds, and glasses or glass ceramics containing Li-BO compounds such as LiBO2 and Li3BO3 as base materials to which materials such as Li2SO4 and Li2CO3 have been added can be used.

[0170] The polymer solid electrolyte may be a compound of a polymer compound and a lithium salt. The polymer compound may have an ethylene oxide structure. A polymer compound having an ethylene oxide structure can contain a large amount of lithium salt. This can further increase ionic conductivity. Examples of the lithium salt that may be used include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), and LiC(SO2CF3)3. One type of lithium salt may be used alone, or two or more types may be used in combination.

[0171] As the complex hydride solid electrolyte, LiBH4-LiI, LiBH4-P2S5, etc. can be used.

[0172] The electrolyte layer 302 may contain a solid electrolyte as a main component. That is, the electrolyte layer 302 may contain a solid electrolyte in a mass ratio of, for example, 70% or more (70 mass % or more) of the solid electrolyte relative to the entire electrolyte layer 302.

[0173] According to the above configuration, the output characteristics of the battery 3000 can be further improved.

[0174] The electrolyte layer 302 contains a solid electrolyte as a main component, and may further contain unavoidable impurities, such as starting materials, by-products, and decomposition products used in synthesizing the solid electrolyte.

[0175] The electrolyte layer 302 may contain a solid electrolyte in a mass ratio of 100% relative to the entire electrolyte layer 302, excluding unavoidable impurities, for example.

[0176] According to the above configuration, the output characteristics of the battery 3000 can be further improved.

[0177] The electrolyte layer 302 may contain two or more of the materials listed as solid electrolytes. For example, the electrolyte layer 302 may contain a halide solid electrolyte and a sulfide solid electrolyte.

[0178] The electrolyte layer 302 may be a layer produced by laminating a layer using the solid electrolyte sheet 201 and a layer containing a solid electrolyte having a composition different from that of the solid electrolyte 101 contained in the solid electrolyte sheet 201. The electrolyte layer 302 may be a single layer made of the solid electrolyte sheet 201, or may be two or more layers made of other solid electrolytes.

[0179] The electrolyte layer 302 may be disposed between the layer using the solid electrolyte sheet 201 and the negative electrode 303, and may have a layer containing a solid electrolyte having a reduction potential lower than that of the solid electrolyte 101 contained in the solid electrolyte sheet 201. According to the above configuration, it is possible to suppress reductive decomposition of the solid electrolyte 101 that may occur due to contact between the solid electrolyte 101 and the negative electrode active material, thereby improving the output characteristics of the battery. An example of a solid electrolyte having a reduction potential lower than that of the solid electrolyte 101 is a sulfide solid electrolyte.

[0180] The thickness of the electrolyte layer 302 may be 1 μm or more and 300 μm or less. When the thickness of the electrolyte layer 302 is 1 μm or more, the possibility of short-circuiting between the positive electrode 301 and the negative electrode 303 is reduced. Furthermore, when the thickness of the electrolyte layer 302 is 300 μm or less, high-power operation is facilitated. In other words, if the thickness of the electrolyte layer 302 is appropriately adjusted, sufficient safety of the battery 3000 can be ensured, and the battery 3000 can be operated at high power.

[0181] The thickness of the solid electrolyte sheet 201 included in the electrolyte layer 302 may be 1 μm or more and 20 μm or less. When the thickness of the solid electrolyte sheet 201 is 1 μm or more, the possibility of short-circuiting between the positive electrode 301 and the negative electrode 303 is reduced. Furthermore, when the thickness of the electrolyte layer 302 is 20 μm or less, the internal resistance of the battery is reduced, enabling high-power operation and improving the energy density of the battery 3000. The thickness of the solid electrolyte sheet is defined, for example, by the average value of multiple arbitrary points (e.g., three points) on a cross section parallel to the thickness direction.

[0182] The surface smoothness of the solid electrolyte sheet 201 can be evaluated by at least one of the arithmetic mean height Sa and the maximum height Sz. For example, the arithmetic mean height Sa of the main surface of the solid electrolyte sheet 201, which can be measured using a shape analysis laser microscope (Keyence Corporation, VK-X1000) with an objective lens magnification of 50x, may be 0.40 μm or less. When the main surface of the solid electrolyte sheet 201 exhibits an arithmetic mean height Sa in this range, the above-described effects can be sufficiently obtained. The lower limit of the arithmetic mean height Sa is not particularly limited and is, for example, 0.20 μm. The "main surface" is the surface having the largest area.

[0183] The maximum height Sz of the main surface of the solid electrolyte sheet 201 may be 7.0 μm or less. There is no particular lower limit to the maximum height Sz, and it is, for example, 3.0 μm.

[0184] The arithmetic mean height Sa is a parameter that extends the arithmetic mean roughness Ra (arithmetic mean height of lines) to a surface. The maximum height Sz is a parameter that extends the maximum height Rz (maximum height of lines) to a surface. The arithmetic mean height Sa and the maximum height Sz are both specified in ISO 25178.

[0185] There are no limitations on the shape of the solid electrolyte contained in battery 3000. The shape of the solid electrolyte may be, for example, needle-like, spherical, oval-spherical, etc. The shape of the solid electrolyte may be, for example, particulate.

[0186] At least one of the positive electrode 301 and the negative electrode 303 may contain an electrolyte material, for example, a solid electrolyte. As the solid electrolyte, the solid electrolytes exemplified as materials constituting the electrolyte layer 302 can be used. With the above configuration, the ionic conductivity (e.g., lithium ion conductivity) inside the positive electrode 301 or the negative electrode 303 is increased, enabling high-power operation.

[0187] The positive electrode 301 includes, for example, a positive electrode active material having the property of absorbing and releasing metal ions (e.g., lithium ions). Examples of the positive electrode active material include lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal oxysulfides, and transition metal oxynitrides. Examples of the lithium-containing transition metal oxides include Li(NiCoAl)O2, Li(NiCoMn)O2, and LiCoO2. When a lithium-containing transition metal oxide is used as the positive electrode active material, the manufacturing cost of the electrode can be reduced and the average discharge voltage can be increased. Li(NiCoAl)O2 means that Ni, Co, and Al are contained in any ratio. Li(NiCoMn)O2 means that Ni, Co, and Mn are contained in any ratio.

[0188] When the solid electrolyte contained in the positive electrode 301 is in the form of particles (for example, spheres), the median diameter of the solid electrolyte may be 100 μm or less. When the median diameter of the solid electrolyte is 100 μm or less, the positive electrode active material and the solid electrolyte can be well dispersed in the positive electrode 301. This improves the charge / discharge characteristics of the battery 3000.

[0189] The median diameter of the solid electrolyte contained in the positive electrode 301 may be smaller than the median diameter of the positive electrode active material, which allows the solid electrolyte and the positive electrode active material to be dispersed well.

[0190] The median diameter of the positive electrode active material may be 0.1 μm or more and 100 μm or less. When the median diameter of the positive electrode active material is 0.1 μm or more, the positive electrode active material and the solid electrolyte can be well dispersed in the positive electrode 301. As a result, the charge / discharge characteristics of the battery 3000 are improved. When the median diameter of the positive electrode active material is 100 μm or less, the lithium diffusion rate within the positive electrode active material is improved. As a result, the battery 3000 can operate at high power.

[0191] When the volume fraction of the positive electrode active material and solid electrolyte contained in the positive electrode 301 is "v1:100-v1," the relationship 30≦v1≦95 may be satisfied. Here, v1 represents the volume fraction of the positive electrode active material when the total volume of the positive electrode active material and solid electrolyte contained in the positive electrode 301 is taken as 100. When 30≦v1 is satisfied, it is easy to ensure a sufficient energy density of the battery 3000. When v3≦95 is satisfied, it is easier for the battery 3000 to operate at high output.

[0192] The thickness of the positive electrode 301 may be 10 μm or more and 500 μm or less. When the thickness of the positive electrode 301 is 10 μm or more, it is easy to ensure a sufficient energy density of the battery 3000. When the thickness of the positive electrode 301 is 500 μm or less, it is easier for the battery 3000 to operate at high power.

[0193] The negative electrode 303 includes, for example, a material having the property of absorbing and releasing metal ions (e.g., lithium ions) as the negative electrode active material. Examples of the negative electrode active material include metal materials, carbon materials, oxides, nitrides, tin compounds, and silicon compounds. The metal material may be a single metal or an alloy. Examples of the metal material include lithium metal and lithium alloys. Examples of the carbon material include natural graphite, coke, partially graphitized carbon, carbon fiber, spherical carbon, artificial graphite, and amorphous carbon. The use of silicon (Si), tin (Sn), silicon compounds, or tin compounds can improve the capacity density of the battery. The use of an oxide compound containing titanium (Ti) or niobium (Nb) as the active material 112 can improve the safety of the battery.

[0194] The median diameter of the negative electrode active material may be 0.1 μm or more and 100 μm or less. When the median diameter of the negative electrode active material is 0.1 μm or more, the negative electrode active material and the solid electrolyte can be well dispersed in the negative electrode 303. This improves the charge / discharge characteristics of the battery 3000. When the median diameter of the negative electrode active material is 100 μm or less, the lithium diffusion rate within the negative electrode active material improves. This allows the battery 3000 to operate at high power.

[0195] The median diameter of the negative electrode active material may be larger than the median diameter of the solid electrolyte, which allows the solid electrolyte and the negative electrode active material to be dispersed well.

[0196] When the volume fraction of the negative electrode active material and solid electrolyte contained in the negative electrode 303 is "v2:100-v2," the relationship 30≦v2≦95 may be satisfied. Here, v2 represents the volume fraction of the negative electrode active material when the total volume of the negative electrode active material and solid electrolyte contained in the negative electrode 303 is taken as 100. When 30≦v2 is satisfied, it is easy to ensure a sufficient energy density of the battery 3000. When v2≦95 is satisfied, it is easier for the battery 3000 to operate at high output.

[0197] The thickness of the negative electrode 303 may be 10 μm or more and 500 μm or less. When the thickness of the negative electrode 303 is 10 μm or more, it is easy to ensure a sufficient energy density of the battery 3000. When the thickness of the negative electrode 303 is 500 μm or less, it is easier for the battery 3000 to operate at high power.

[0198] The positive electrode active material and the negative electrode active material may be coated with a coating material to reduce the interfacial resistance between each active material and the solid electrolyte. Materials with low electronic conductivity can be used as the coating material. Examples of the coating material include oxide materials and oxide solid electrolytes.

[0199] Examples of oxide materials used for the coating material include SiO2, Al2O3, TiO2, B2O3, Nb2O5, WO3, and ZrO2.

[0200] Examples of oxide solid electrolytes used in coating materials include Li-Nb-O compounds such as LiNbO3, Li-BO compounds such as LiBO2 and Li3BO3, Li-Al-O compounds such as LiAlO2, Li-Si-O compounds such as Li4SiO4, Li2SO4, and Li4Ti5O. 12 Examples of oxide solid electrolytes include Li-Ti-O compounds such as Li2ZrO3, Li-Zr-O compounds such as Li2MoO3, Li-VO compounds such as LiV2O5, and Li-WO compounds such as Li2WO4. Oxide solid electrolytes have high ionic conductivity and high potential stability. Therefore, using oxide solid electrolytes as coating materials can further improve the charge / discharge efficiency of batteries.

[0201] At least one selected from the group consisting of the positive electrode 301, the electrolyte layer 302, and the negative electrode 303 may contain a binder to improve adhesion between particles. Examples of the binder include those described above for the binder 103. When the binder contains an elastomer, each of the positive electrode 301, the electrolyte layer 302, and the negative electrode 303 included in the battery 3000 exhibits excellent flexibility and elasticity, thereby improving the durability of the battery.

[0202] At least one selected from the group consisting of the positive electrode 301, the electrolyte layer 302, and the negative electrode 303 may contain a non-aqueous electrolyte solution, a gel electrolyte, or an ionic liquid in order to facilitate the exchange of lithium ions and improve the output characteristics of the battery 3000.

[0203] The nonaqueous electrolyte contains a nonaqueous solvent and a lithium salt dissolved in the nonaqueous solvent. Examples of nonaqueous solvents that can be used include cyclic carbonate ester solvents, chain carbonate ester solvents, cyclic ether solvents, chain ether solvents, cyclic ester solvents, chain ester solvents, and fluorine-containing solvents. Examples of cyclic carbonate ester solvents include ethylene carbonate, propylene carbonate, and butylene carbonate. Examples of chain carbonate ester solvents include dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. Examples of cyclic ether solvents include tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane. Examples of chain ether solvents include 1,2-dimethoxyethane and 1,2-diethoxyethane. Examples of cyclic ester solvents include γ-butyrolactone. Examples of chain ester solvents include methyl acetate. Examples of fluorine-containing solvents include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate. As the non-aqueous solvent, one non-aqueous solvent selected from these may be used alone, or a mixture of two or more non-aqueous solvents selected from these may be used.

[0204] The non-aqueous electrolyte may contain at least one fluorine solvent selected from the group consisting of fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate.

[0205] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), and LiC(SO2CF3)3. As the lithium salt, one type of lithium salt selected from these may be used alone, or a mixture of two or more types of lithium salts selected from these may be used. The concentration of the lithium salt may be, for example, 0.5 mol / L or more and 2 mol / L or less.

[0206] The gel electrolyte may be a polymer material containing a non-aqueous electrolyte, such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.

[0207] The cations constituting the ionic liquid may be aliphatic chain quaternary cations such as tetraalkylammonium and tetraalkylphosphonium, aliphatic cyclic ammoniums such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, and piperidiniums, and nitrogen-containing heterocyclic aromatic cations such as pyridiniums and imidazoliums. The anion constituting the ionic liquid may be PF6 - , BF4 - , SbF 6- - , AsF6 - , SO3CF3 - , N(SO2F)2 - , N(SO2CF3)2 - , N(SO2C2F5)2 - , N(SO2CF3)(SO2C4F9) - , and C(SO2CF3)3 - The ionic liquid may contain a lithium salt.

[0208] At least one of the positive electrode 301 and the negative electrode 303 may contain a conductive additive to enhance electronic conductivity. Examples of conductive additives that can be used include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black and ketjen black, conductive fibers such as carbon fiber and metal fiber, conductive powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymers such as polyaniline, polypyrrole, and polythiophene. Using a carbon material as a conductive additive can reduce costs.

[0209] Examples of the shape of the battery include coin type, cylindrical type, square type, sheet type, button type, flat type, and laminate type. [Example]

[0210] The present disclosure will be described in detail below using examples and comparative examples. Note that the solid electrolyte composition, solid electrolyte sheet, and battery of the present disclosure are not limited to the following examples.

[0211] <Example 1-1> [Preparation of halide solid electrolytes] In an argon glove box with a dew point of -60°C or less, raw material powders of YCl3, LiCl, and LiBr were weighed out in a molar ratio of YCl3:LiCl:LiBr = 1:1:2. These raw material powders were then mixed. The resulting mixture was fired in an electric furnace at 520°C for 2 hours. This produced a halide solid electrolyte, Li3YBr2Cl4 (hereinafter referred to as "LYBC").

[0212] [solvent] In all of the following steps, a commercially available dehydrated solvent or a solvent dehydrated by nitrogen bubbling and having a water content of 10 mass ppm or less was used.

[0213] [Preparation of resin binder solution] A solvent was added to the resin binder so that the concentration of the resin binder was 5% by mass or more and 6% by mass or less, and the resin binder was dissolved or dispersed in the solvent. Thereafter, the resin binder solution was dehydrated by nitrogen bubbling until the water content was 10 ppm by mass or less.

[0214] In Example 1-1, mesitylene was used as the solvent for the resin binder solution. SEBS (Tuftec (registered trademark) N504, manufactured by Asahi Kasei Corporation), which is a hydrogenated styrene-based thermoplastic elastomer, was used as the resin binder.

[0215] [Preparation of solid electrolyte composition] In an argon glove box with a dew point of -60°C or less, mesitylene was added to LYBC so that the solid content concentration was 35% by mass. LYBC was wet-pulverized using a planetary ball mill (Fritsche, P-7 model) and dispersed in mesitylene. This resulted in a LYBC dispersion. The particle size (median diameter) of LYBC was 0.7 μm.

[0216] Next, a homogenizer (HG-200, manufactured by AS ONE Corporation) and a generator (K-20S, manufactured by AS ONE Corporation) were used to disperse the mixture by shearing, and the mixture was then heated for approximately 20 cm 3 A resin binder solution was added to the LYBC dispersion. This resulted in a mixed dispersion containing LYBC and the resin binder. The amount of the resin binder solution was adjusted so that the mass ratio of LYBC:SEBS was 100:3. Furthermore, mesitylene was added to the mixed dispersion so that the solid content concentration was 30 mass%, and the mixed dispersion was kneaded at 3000 rpm for 10 minutes. One day later, the mixed dispersion was kneaded using a planetary centrifugal mixer (ARE-310, manufactured by THINKY Corporation) at 1600 rpm for 3 minutes. This resulted in a solid electrolyte composition of Example 1-1.

[0217] In the solid electrolyte composition of Example 1-1, the halide solid electrolyte was LYBC, the solvent was mesitylene (δp=0.6), and the resin binder was SEBS.

[0218] The solid content concentration of the solid electrolyte composition of Example 1-1 was measured using a heat-drying moisture meter (MX-50, manufactured by A&D Co., Ltd.) and was found to be 32.2 mass %.

[0219] [Fabrication of solid electrolyte sheets] In an argon glove box with a dew point of -60°C or less, the solid electrolyte composition of Example 1-1 was applied onto a copper foil using a 70 μm thick metal mask and a squeegee. The applied film was dried in a vacuum at 100°C for 1 hour. This resulted in a solid electrolyte sheet of Example 1-1.

[0220] The polarity term Δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-1 was 0.6.

[0221] <Example 1-2> In preparing the solid electrolyte composition, mixed xylene was used as the solvent. Except for this, the solid electrolyte composition and solid electrolyte sheet of Example 1-2 were prepared in the same manner as in Example 1-1. The mixed xylene was a mixed solvent containing o-xylene, m-xylene, p-xylene, and ethylbenzene in a mass ratio of 24:42:18:16. The solid content concentration of the solid electrolyte composition of Example 1-2 was 31.2 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-2 was 1.6.

[0222] <Examples 1-3> In preparing the solid electrolyte composition, tetralin was used as the solvent. Except for this, the solid electrolyte composition and solid electrolyte sheet of Example 1-3 were prepared in the same manner as in Example 1-1. The solid content concentration of the solid electrolyte composition of Example 1-3 was 31.3 mass%. The polarity term Δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-3 was 2.0.

[0223] <Examples 1-4> Tetralin was used as the solvent when preparing the LYBC dispersion using a planetary ball mill. p-Chlorotoluene was used as the solvent in the resin binder solution. p-Chlorotoluene was used as the solvent when mixing the LYBC dispersion and the resin binder solution using a homogenizer. Except for these, the solid electrolyte composition and solid electrolyte sheet of Example 1-4 were prepared in the same manner as in Example 1-1. In the solvent contained in the solid electrolyte composition of Example 1-4, the ratio of tetralin to p-chlorotoluene was tetralin:p-chlorotoluene = 75:25 by mass. The solid content concentration of the solid electrolyte composition of Example 1-4 was 31.0 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-4 was 3.0.

[0224] <Examples 1-5> [Preparation of solid electrolyte composition] In an argon glove box with a dew point below -60°C, o-chlorotoluene was added to LYBC to a solids concentration of 35% by mass. LYBC was wet-pulverized using a bead mill wet-type fine grinding and dispersion machine (Ashizawa Finetech, LMZ015) and dispersed in a solvent to obtain a LYBC dispersion. The particle size of the LYBC was 0.4 μm.

[0225] Thereafter, a solid electrolyte composition and a solid electrolyte sheet of Example 1-5 were prepared in the same manner as in Example 1-1, except for the following differences. The differences were that mixed xylene was used as the solvent in the resin binder solution, and that mixed xylene was used as the solvent when mixing the LYBC dispersion and the resin binder solution using a homogenizer. The composition of the mixed xylene was as described in Example 1-2. In the solvent contained in the solid electrolyte composition of Example 1-5, the ratio of o-chlorotoluene to mixed xylene was o-chlorotoluene:mixed xylene = 78:22 by mass. The solid content concentration of the solid electrolyte composition of Example 1-5 was 30.9 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-5 was 4.0.

[0226] <Examples 1-6> When preparing the LYBC dispersion using a bead mill, p-chlorotoluene was used as the solvent. Toluene was used as the solvent in the resin binder solution. When mixing the LYBC dispersion and the resin binder solution using a homogenizer, toluene was used as the solvent. Except for these, the solid electrolyte compositions and solid electrolyte sheets of Examples 1-6 were prepared in the same manner as in Examples 1-5. In the solvent contained in the solid electrolyte compositions of Examples 1-6, the ratio of p-chlorotoluene to toluene was p-chlorotoluene:toluene = 74:26 by mass. The solid content concentration of the solid electrolyte composition of Examples 1-6 was 32.5 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Examples 1-6 was 4.7.

[0227] <Examples 1-7> When preparing the LYBC dispersion using a bead mill, p-chlorotoluene was used as the solvent. Mixed xylene was used as the solvent for the resin binder solution. When mixing the LYBC dispersion and the resin binder solution using a homogenizer, mixed xylene was used as the solvent. Except for these, the solid electrolyte composition and solid electrolyte sheet of Example 1-7 were prepared in the same manner as in Example 1-5. In the solvent contained in the solid electrolyte composition of Example 1-7, the ratio of p-chlorotoluene to mixed xylene was p-chlorotoluene:mixed xylene = 74:26 by mass. The solid content concentration of the solid electrolyte composition of Example 1-7 was 30.2 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-7 was 4.8.

[0228] <Example 1-8> When preparing the LYBC dispersion using a bead mill, o-chlorotoluene was used as the solvent. Chlorobenzene was used as the solvent in the resin binder solution. When mixing the LYBC dispersion and the resin binder solution using a homogenizer, chlorobenzene was used as the solvent. Except for these, the solid electrolyte composition and solid electrolyte sheet of Example 1-8 were prepared in the same manner as in Example 1-5. In the solvent contained in the solid electrolyte composition of Example 1-8, the ratio of o-chlorotoluene to chlorobenzene was o-chlorotoluene:chlorobenzene = 78:22 by mass. The solid content concentration of the solid electrolyte composition of Example 1-8 was 31.5 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-8 was 4.8.

[0229] <Examples 1-9> When preparing the LYBC dispersion using a bead mill, p-chlorotoluene was used as the solvent. Tetralin was used as the solvent in the resin binder solution. When mixing the LYBC dispersion and the resin binder solution using a homogenizer, tetralin was used as the solvent. Except for these, the solid electrolyte compositions and solid electrolyte sheets of Examples 1-9 were prepared in the same manner as Examples 1-5. In the solvent contained in the solid electrolyte compositions of Examples 1-9, the ratio of p-chlorotoluene to tetralin was p-chlorotoluene:tetralin = 74:26 by mass. The solid content concentration of the solid electrolyte compositions of Examples 1-9 was 31.3 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte compositions of Examples 1-9 was 5.0.

[0230] <Examples 1-10> [Preparation of solid electrolyte composition] In an argon glove box with a dew point of -60°C or less, p-chlorotoluene was added to LYBC to a solids concentration of 35% by mass. LYBC was wet-pulverized using a wet-type micro-pulverizer / disperser equipped with a bead mill and dispersed in a solvent to obtain a LYBC dispersion. The particle size of the LYBC was 0.4 μm.

[0231] Next, a tabletop quick homo mixer (manufactured by Mizuho Kogyo Co., Ltd., LR-1F) and a replacement blade (manufactured by Mizuho Kogyo Co., Ltd., Ultra φ36 mm) were used to disperse the mixture by shearing, and the mixture was stirred at a speed of approximately 200 cm 3 A resin binder solution was added to the LYBC dispersion. This resulted in a mixed dispersion containing LYBC and a resin binder. The amount of the resin binder solution was adjusted so that the mass ratio of LYBC:SEBS was 100:3. In the resin binder solution, tetralin was used as the solvent. Tetralin was further added to the mixed dispersion so that the solid content concentration was 30 mass%, and the mixed dispersion was kneaded at 1200 rpm for 60 minutes. One day later, the mixed dispersion was kneaded using a planet-rotation mixer at 1600 rpm for 3 minutes. This resulted in a solid electrolyte composition of Example 1-10. Using the solid electrolyte composition of Example 1-10, a solid electrolyte sheet of Example 1-10 was produced in the same manner as in Example 1-1.

[0232] In the solvent contained in the solid electrolyte composition of Example 1-10, the ratio of p-chlorotoluene to tetralin was p-chlorotoluene:tetralin=76:24 by mass. The solid content concentration of the solid electrolyte composition of Example 1-10 was 30.8 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-10 was 5.1.

[0233] <Example 1-11> When preparing the LYBC dispersion using a bead mill, p-chlorotoluene was used as the solvent. A mixed solvent containing tetralin and p-chlorotoluene in a mass ratio of 45:55 was used as the solvent for the resin binder solution. When mixing the LYBC dispersion and the resin binder solution using a homogenizer, no solvent was used. Except for these, the solid electrolyte composition and solid electrolyte sheet of Example 1-11 were prepared in the same manner as in Example 1-5. In the solvent contained in the solid electrolyte composition of Example 1-11, the mass ratio of p-chlorotoluene to tetralin was p-chlorotoluene:tetralin = 90:10. The solid content concentration of the solid electrolyte composition of Example 1-11 was 31.3 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-11 was 5.7.

[0234] <Example 1-12> When preparing the LYBC dispersion using a bead mill, p-chlorotoluene was used as the solvent. Anisole was used as the solvent in the resin binder solution. When mixing the LYBC dispersion and the resin binder solution using a homogenizer, anisole was used as the solvent. Except for these, the solid electrolyte composition and solid electrolyte sheet of Example 1-12 were prepared in the same manner as in Example 1-5. In the solvent contained in the solid electrolyte composition of Example 1-12, the ratio of p-chlorotoluene to anisole was p-chlorotoluene:anisole = 76:24 by mass. The solid content concentration of the solid electrolyte composition of Example 1-12 was 31.2 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 1-12 was 5.7.

[0235] <Comparative Example 1-1> In preparing the solid electrolyte composition, heptane was used as the solvent. Except for this, the solid electrolyte composition and solid electrolyte sheet of Comparative Example 1-1 were prepared in the same manner as in Example 1-1. The solid content concentration of the solid electrolyte composition of Comparative Example 1-1 was 35.8 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Comparative Example 1-1 was 0.

[0236] <Comparative Example 1-2> When preparing the LYBC dispersion using a bead mill, p-chlorotoluene was used as the solvent. o-chlorotoluene was used as the solvent for the resin binder solution. o-chlorotoluene was used as the solvent for mixing the LYBC dispersion and the resin binder solution using a homogenizer. Except for these, the solid electrolyte composition and solid electrolyte sheet of Comparative Example 1-2 were prepared in the same manner as in Example 1-5. In the solvent contained in the solid electrolyte composition of Comparative Example 1-2, the ratio of p-chlorotoluene to o-chlorotoluene was p-chlorotoluene:o-chlorotoluene = 74:26 by mass. The solid content concentration of the solid electrolyte composition of Comparative Example 1-2 was 31.8 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Comparative Example 1-2 was 5.9.

[0237] <Comparative Example 1-3> In preparing the solid electrolyte composition, p-chlorotoluene was used as the solvent. Except for this, the solid electrolyte composition and solid electrolyte sheet of Comparative Example 1-3 were prepared in the same manner as in Examples 1-5. The solid content concentration of the solid electrolyte composition of Comparative Example 1-3 was 32.2 mass%. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Comparative Example 1-3 was 6.2.

[0238] <Comparative Example 1-4> When preparing the LYBC dispersion using a bead mill, p-chlorotoluene was used as the solvent. o-Dichlorobenzene was used as the solvent for the resin binder solution. o-Dichlorobenzene was used as the solvent for mixing the LYBC dispersion and the resin binder solution using a homogenizer. Except for these, the solid electrolyte composition and solid electrolyte sheet of Comparative Example 1-4 were prepared in the same manner as in Examples 1-5. In the solvent contained in the solid electrolyte composition of Comparative Example 1-4, the ratio of p-chlorotoluene to o-dichlorobenzene was p-chlorotoluene:o-dichlorobenzene = 76:24 by mass. The solid content concentration of the solid electrolyte composition of Comparative Example 1-4 was 32.0% by mass. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Comparative Example 1-4 was 6.2.

[0239] <Comparative Example 1-5> When preparing the LYBC dispersion using a bead mill, p-chlorotoluene was used as the solvent. 3,4-Dichlorotoluene was used as the solvent for the resin binder solution. When mixing the LYBC dispersion and the resin binder solution using a homogenizer, 3,4-Dichlorotoluene was used as the solvent. Except for these, the solid electrolyte compositions and solid electrolyte sheets of Comparative Examples 1-5 were prepared in the same manner as Examples 1-5. In the solvent contained in the solid electrolyte compositions of Comparative Examples 1-5, the ratio of p-chlorotoluene to 3,4-dichlorotoluene was p-chlorotoluene:3,4-dichlorotoluene = 74:26 by mass. The solid content concentration of the solid electrolyte composition of Comparative Examples 1-5 was 31.9% by mass. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Comparative Examples 1-5 was 7.0.

[0240] <Reference example 1-1> [Preparation of solid electrolyte composition] In an argon glove box with a dew point of -60°C or less, p-chlorotoluene was added to the sulfide solid electrolyte Li2S-P2S5 (hereinafter referred to as "LPS") so that the solids concentration was 35% by mass. LPS was dispersed in p-chlorotoluene using a homogenizer (HG-200, manufactured by AS ONE Corporation) and a generator (K-20S, manufactured by AS ONE Corporation). This resulted in an LPS dispersion.

[0241] Next, a homogenizer was used to disperse the mixture by shearing, and the mixture was then mixed for about 20 cm. 3 The resin binder solution was added to the LPS dispersion. This resulted in a mixed dispersion containing LPS and the resin binder. The amount of the resin binder solution was adjusted so that the mass ratio of LPS:SEBS was 100:3. In the resin binder solution, tetralin was used as the solvent. Tetralin was further added to the mixed dispersion so that the solid content concentration was 30 mass%, and the mixed dispersion was kneaded at 3000 rpm for 10 minutes. After one day, the mixed dispersion was kneaded using a planet-revolution mixer at 1600 rpm for 3 minutes. This resulted in a solid electrolyte composition of Reference Example 1-1. Using the solid electrolyte composition of Reference Example 1-1, a solid electrolyte sheet of Reference Example 1-1 was produced in the same manner as in Example 1-1.

[0242] In the solvent contained in the solid electrolyte composition of Reference Example 1-1, the ratio of p-chlorotoluene to tetralin was p-chlorotoluene:tetralin=80:20 by mass. The polarity term Δp of the HSP of the solvent contained in the solid electrolyte composition of Reference Example 1-1 was 5.3.

[0243] <Reference example 1-2> In the preparation of the solid electrolyte composition, p-chlorotoluene was used as the solvent. Except for this, the solid electrolyte composition and solid electrolyte sheet of Reference Example 1-2 were prepared in the same manner as in Reference Example 1-1. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Reference Example 1-2 was 6.2.

[0244] <Evaluation of solid electrolyte composition> [Rheology measurement] Rheology measurements were carried out under the following conditions for the solid electrolyte compositions of Examples 1-1 to 1-11, Comparative Examples 1-1 to 1-5, Reference Examples 1-1 and 1-2.

[0245] Rheological measurements of solid electrolyte compositions were performed in a dry room with a dew point below -40°C. A viscosity and viscoelasticity measuring device (Thermo Fisher Scientific, HAAKE MARS40) and a 35 mm diameter, 2° angle cone-plate (Thermo Fisher Scientific, C35 / 2 Ti) were used. Viscosity measurements were performed at 25°C in rate control mode (CR) from shear rates of 0.1 / s to 1000 / s, and viscosities at shear rates of 1 / s and 1000 / s were obtained. Strain γ was measured at 25°C in stress control mode (CS) from shear stresses of 0.1 Pa to 200 Pa, and yield stress was calculated as described above. Storage modulus G' and loss tangent tanδ were measured at 25°C in strain control mode (CD) from 0.01% to 10,000% strain at a frequency of 1 Hz from 10% to 25% strain.

[0246] <Evaluation of solid electrolyte sheets> [Surface roughness measurement] The surface roughness of the solid electrolyte sheets of Examples 1-1 to 1-11, Comparative Examples 1-1 to 1-5, Reference Examples 1-1 and 1-2 was measured. The measurements were carried out in an argon glove box with a dew point of −60°C or less using a shape analysis laser microscope (Keyence Corporation, VK-X1000). Images of the surfaces of the solid electrolyte sheets were taken at a 50x objective lens magnification, and the images were analyzed to determine the arithmetic mean height Sa and maximum height Sz.

[0247] The results of the above measurements are shown in Table 1.

[0248] [Table 1]

[0249] As shown in Table 1, when LYBC was used as the solid electrolyte, a correlation was observed between the polarity term δp of HPS and the surface roughness of the solid electrolyte sheet. When a solid electrolyte composition containing a solvent with a polarity term δp of HPS greater than 0 and less than 5.9 was used, the surface roughness of the solid electrolyte sheet was small and the surface smoothness of the solid electrolyte sheet was high. When a solid electrolyte composition containing a solvent with a polarity term δp of HPS greater than 0.6 and less than 5.7 was used, the surface roughness of the solid electrolyte sheet was smaller and the surface smoothness of the solid electrolyte sheet was higher.

[0250] As can be seen from the results of Reference Examples 1-1 and 1-2, when LPS was used as the solid electrolyte, the surface roughness of the solid electrolyte sheet did not depend on the value of the polar term Δp of the HSP of the solvent.

[0251] <Example 2-1> [Preparation of solid electrolyte composition] In an argon glove box with a dew point below -60°C, p-chlorotoluene was added to LYBC to a solids concentration of 35% by mass. LYBC was wet-pulverized using a wet-type micro-pulverizer / disperser equipped with a bead mill and dispersed in a solvent to obtain a LYBC dispersion. The average particle size of LYBC was 0.4 μm.

[0252] A resin binder solution was prepared by mixing a resin binder and a solvent. Mixed xylene was used as the solvent for the resin binder solution. The mixed xylene was a mixed solvent containing o-xylene, m-xylene, p-xylene, and ethylbenzene in a mass ratio of 24:42:18:16. SEBS (Tuftec (registered trademark) N504, manufactured by Asahi Kasei Corporation), a hydrogenated styrene-based thermoplastic elastomer, was used as the resin binder.

[0253] Next, the mixture was dispersed by shear using a homogenizer and a generator, and the mixture was then mixed for about 20 cm 3The resin binder solution was added to the LYBC dispersion. This resulted in a mixed dispersion containing LYBC and the resin binder. The amount of the resin binder solution was adjusted so that the mass ratio of LYBC:SEBS was 100:3. Furthermore, mixed xylene was added to the mixed dispersion so that the solid content concentration was 30 mass%, and the mixed dispersion was kneaded at 3000 rpm for 10 minutes. After one day, the mixed dispersion was kneaded using a planetary centrifugal mixer at 1600 rpm for 3 minutes. This resulted in a solid electrolyte composition of Example 2-1.

[0254] The solid content of the solid electrolyte composition was measured using a heat-drying moisture meter. The solid content was 31.2% by mass. In the solvent contained in the solid electrolyte composition of Example 2-1, the ratio of p-chlorotoluene to mixed xylene was p-chlorotoluene:mixed xylene = 78:22 by mass. The polarity term δp of the HSP of the solvent contained in the solid electrolyte composition of Example 2-1 was 5.0.

[0255] [Fabrication of solid electrolyte sheets] In an argon glove box with a dew point of −60° C. or less, the solid electrolyte composition of Example 2-1 was applied to a carbon-coated aluminum foil using a four-sided applicator with a gap of 100 μm to form a coating film. The coating film was dried in a vacuum at 100° C. for 1 hour to produce a solid electrolyte sheet of Example 2-1.

[0256] <Example 2-2> In preparing the solid electrolyte composition, SEBS (Tuftec (registered trademark) H1053, manufactured by Asahi Kasei Corporation) was used as the resin binder. Except for this, the solid electrolyte composition and solid electrolyte sheet of Example 2-2 were prepared in the same manner as in Example 2-1. The solid content concentration of the solid electrolyte composition of Example 2-2 was 31.1 mass%.

[0257] <Example 2-3> In preparing the solid electrolyte composition, SEPS (Septon (registered trademark) 2005, manufactured by Kuraray Co., Ltd.) was used as the resin binder. Except for this, the solid electrolyte composition and solid electrolyte sheet of Example 2-3 were prepared in the same manner as in Example 2-1. The solid content concentration of the solid electrolyte composition of Example 2-3 was 31.2 mass%.

[0258] <Example 2-4> In preparing the solid electrolyte composition, SEEPS (Septon (registered trademark) 4099, manufactured by Kuraray Co., Ltd.) was used as the resin binder. Except for this, the solid electrolyte composition and solid electrolyte sheet of Example 2-4 were prepared in the same manner as in Example 2-1. The solid content concentration of the solid electrolyte composition of Example 2-4 was 31.9 mass%.

[0259] <Example 2-5> In preparing the solid electrolyte composition, a mixture containing SEEPS (Septon (registered trademark) 4099 manufactured by Kuraray Co., Ltd.) and PVDF (KYNAR (registered trademark) 761 manufactured by Arkema) in a mass ratio of 1:1 was used as the resin binder. Except for this, the solid electrolyte composition and solid electrolyte sheet of Example 2-5 were prepared in the same manner as in Example 2-1. The solid content concentration of the solid electrolyte composition of Example 2-5 was 31.2 mass%.

[0260] <Example 2-6> In preparing the solid electrolyte composition, SBR (Tufden (registered trademark) 2100R, manufactured by Asahi Kasei Corporation) was used as the resin binder. Except for this, the solid electrolyte composition and solid electrolyte sheet of Example 2-6 were prepared in the same manner as in Example 2-1. The solid content concentration of the solid electrolyte composition of Example 2-6 was 31.1 mass%.

[0261] <Evaluation of solid electrolyte sheets> [Ionic conductivity measurement] The ionic conductivity of the solid electrolyte sheets of Examples 2-1 to 2-6 was measured by the following method.

[0262] In an argon glove box with a dew point of -60°C or less, the solid electrolyte sheet was punched out together with the substrate using a 20mm x 20mm square punch. The substrate, solid electrolyte sheet, solid electrolyte sheet, substrate, and silicone rubber film were then stacked in this order in a mold to produce a laminate. The laminate was then pressure-molded at 100°C and a pressure of 620 MPa. The silicone rubber film was removed, and the peripheral edges of the laminate were cut off using a press cutter. Copper foil with tab leads was attached to each substrate. The laminate was vacuum-sealed in an aluminum laminate film to produce a sample for ionic conductivity measurement.

[0263] Next, the metal plate, silicone rubber sheet, sample, silicone rubber sheet, and metal plate were sandwiched in that order, and the sample was restrained by tightening four bolts (M6) with a torque of 1 N·m. The sample was then placed in a thermostatic chamber at 25°C. The ionic conductivity of each sample was determined by electrochemical AC impedance spectroscopy using a potentiostat / galvanostat (Solartron Analytical, 1470E) and a frequency response analyzer (Solartron Analytical, 1255B).

[0264] [Rheology measurement] The solid electrolyte sheets of Examples 2-1 to 2-6 were subjected to rheology measurements using the method described above.

[0265] [Surface roughness measurement] The surface roughness of the solid electrolyte sheets of Examples 2-1 to 2-6 was measured by the method described above.

[0266] The results of the above measurements are shown in Table 2. The resin binder types A to F in Table 2 correspond to the following resins, respectively. A: Hydrogenated styrene-based thermoplastic elastomer (SEBS) Tuftec N504 B: Hydrogenated styrene-based thermoplastic elastomer (SEBS) Tuftec H1053 C: Hydrogenated styrene thermoplastic elastomer (SEPS) Septon 2005 D: Hydrogenated styrene thermoplastic elastomer (SEEPS) Septon 4099 E: A mixture containing hydrogenated styrene-based thermoplastic elastomer (SEEPS) Septon 4099 and polyvinylidene fluoride (PVDF) KYNAR 761 in a 1:1 mass ratio. F: Solution polymerization styrene-butadiene rubber (SBR) Tufden 2100R

[0267] [Table 2]

[0268] As shown in Table 2, the solid electrolyte sheets produced from the solid electrolyte compositions containing a solvent with an HSP polarity term δp value greater than 0 and less than 5.9, or a solvent with an HSP polarity term δp value of 0.6 to 5.7 and an elastomer resin binder containing a repeating unit derived from styrene, had low surface roughness and high surface smoothness. All of the solid electrolyte sheets in Examples 2-1 to 2-6 exhibited high ionic conductivities of 0.1 mS / cm or more.

[0269] <Example 3-1> [Fabrication of solid electrolyte sheets] In an argon glove box with a dew point of -60°C or less, the solid electrolyte composition of Example 1-9 was applied to a polyimide film using a four-sided applicator with a gap of 100 μm to form a coating film. The coating film was dried in a vacuum at 100°C for 1 hour to produce the solid electrolyte sheet of Example 3-1. The thickness of the solid electrolyte sheet of Example 3-1 was 8 μm after pressing.

[0270] [Battery construction] The negative electrode mixture containing graphite, LPS, and SEBS was applied to a copper foil and dried, resulting in a negative electrode with a thickness of 90 μm after pressing.

[0271] A cathode mixture containing Li(Ni,Co,Mn)O2, LPS, and SEBS was applied to a copper foil and dried, resulting in a cathode with a thickness of 55 μm after pressing.

[0272] In an argon glove box with a dew point of -60°C or less, the solid electrolyte sheet was punched out together with the substrate using a 20 mm x 20 mm square punch. Next, a negative electrode, a sulfide solid electrolyte (LPS, 15 μm thick after pressing), a solid electrolyte sheet, a substrate, and a silicone rubber film were laminated in this order in a mold to produce a laminate. The laminate was pressed at 100°C and a pressure of 150 MPa to transfer the solid electrolyte sheet onto the negative electrode. After removing the substrate and silicone rubber film from the laminate, the negative electrode and solid electrolyte sheet laminate, a positive electrode, and a silicone rubber film were laminated in this order in a mold to produce a power generation element. The power generation element was pressure-molded at 100°C and a pressure of 620 MPa. The silicone rubber film was removed, and the thickness of the power generation element was measured using a micrometer. The thickness of the power generation element of Example 3-1 was found to be 190 μm. Next, the peripheral edges of the power generation element were cut off using a press cutter. Copper foil with tab leads was attached to each of the negative and positive electrodes. The power generating element was vacuum sealed in a container made of an aluminum laminate film to prepare a battery of Example 3-1.

[0273] <Example 3-2> [Fabrication of solid electrolyte sheets] In an argon glove box with a dew point of -60°C or less, the solid electrolyte composition of Example 1-10 was applied to a positive electrode using a die coater to form a coating film. The coating film was dried with hot air at a temperature of 80°C to 110°C to produce a solid electrolyte sheet of Example 3-2. The thickness of the solid electrolyte sheet of Example 3-2 was 6 μm after pressing.

[0274] [Battery construction] In an argon glove box with a dew point of -60°C or less, the solid electrolyte sheet was punched out together with the positive electrode using a 20 mm x 20 mm square punch. Next, the negative electrode, sulfide solid electrolyte (LPS, 15 μm thick after pressing), solid electrolyte sheet, positive electrode, and silicone rubber film were laminated in this order in a mold to produce a power generating element. The power generating element was pressure-molded at 100°C and a pressure of 620 MPa. The silicone rubber film was removed, and the thickness of the power generating element was measured using a micrometer. As a result, the thickness of the power generating element of Example 3-2 was found to be 186 μm. Next, the peripheral edges of the power generating element were cut off using a press cutter. Copper foil with tab leads was attached to each of the negative and positive electrodes. The power generating element was vacuum-sealed in a container made of aluminum laminate film to produce the battery of Example 3-2.

[0275] <Example 3-3> [Fabrication of solid electrolyte sheets] A negative electrode composite containing graphite, LPS, and SEBS was applied to copper foil and dried. This resulted in a negative electrode with a thickness of 90 μm after pressing. A layer of sulfide solid electrolyte (LPS) was laminated on the negative electrode to a thickness of 15 μm after pressing, producing a laminate.

[0276] In an argon glove box with a dew point of -60°C or less, the solid electrolyte composition of Example 1-10 was applied to a laminate using a die coater to form a coating film. The coating film was dried with hot air at a temperature of 80°C to 110°C to produce a solid electrolyte sheet of Example 3-3. The thickness of the solid electrolyte sheet of Example 3-3 after pressing was 5 μm.

[0277] [Battery construction] A cathode mixture containing Li(Ni,Co,Mn)O2, LPS, and SEBS was applied to a copper foil and dried, resulting in a cathode with a thickness of 55 μm after pressing.

[0278] In an argon glove box with a dew point of -60°C or less, the solid electrolyte sheet was punched out together with the negative electrode using a 20 mm x 20 mm square punch. Next, a laminate of the negative electrode, sulfide solid electrolyte, and solid electrolyte sheet, a positive electrode, and a silicone rubber film were stacked in this order in a mold to produce a power generating element. The power generating element was pressure-molded at 100°C and a pressure of 620 MPa. The silicone rubber film was removed, and the thickness of the battery was measured using a micrometer. As a result, the thickness of the power generating element of Example 3-3 was found to be 184 μm. Next, the peripheral edges of the power generating element were cut off using a press cutter. Copper foil with tab leads was attached to each of the negative and positive electrodes. The power generating element was vacuum-sealed in a container made of aluminum laminate film to produce the battery of Example 3-3.

[0279] <Comparative Example 3-1> In preparing the solid electrolyte sheet, the solid electrolyte composition of Comparative Example 1-3 was used as the solid electrolyte composition. Except for this, the solid electrolyte sheet and battery of Comparative Example 3-1 were prepared in the same manner as in Example 3-1. The thickness of the battery of Comparative Example 3-1 was 299 μm. The thickness of the solid electrolyte sheet of Comparative Example 3-1 after pressing was 90 μm.

[0280] <Battery evaluation> [Charge / discharge test] Charge and discharge tests were carried out on the batteries of Examples 3-1 to 3-3 and Comparative Example 3-1 under the following conditions.

[0281] The metal plate, silicone rubber sheet, battery, silicone rubber sheet, and metal plate were sandwiched in this order, and the battery was restrained by tightening four bolts (M6) with a torque of 1 N·m. The battery was then placed in a thermostatic chamber at 25°C. Next, the battery was charged to a voltage of 4.2 V at a current density of 0.05 C rate, which corresponds to the theoretical capacity of the positive electrode active material (Li(Ni,Co,Mn)O2). The battery was then discharged to a voltage of 2.5 V at a current density of 0.05 C rate. Next, the battery was charged to a voltage of 4.2 V at a current density of 0.05 C rate. The battery was then discharged to a voltage of 2.5 V at a current density of 0.3 C rate. From these measurements, the 0.3 C discharge capacity [Ah / cm] of each battery was calculated. 2 ], 0.3C average discharge voltage [V], and energy density were obtained. The energy density was calculated using the following formula.

[0282] Energy density = 1000 x (0.3C discharge capacity x 0.3C average discharge voltage) / (battery thickness [cm])

[0283] [Surface roughness measurement] The surface roughness of the solid electrolyte sheets of Examples 3-1 to 3-3 and Comparative Example 3-1 was measured by the method described above.

[0284] The results of the above measurements are shown in Table 3.

[0285] [Table 3]

[0286] As shown in Table 3, the batteries of Examples 3-1 to 3-3 had solid electrolyte sheets with thicknesses of 1 μm to 20 μm, and exhibited high energy densities. The thickness of the solid electrolyte sheet used in the battery of Comparative Example 3-1 was 90 μm. The battery of Comparative Example 3-1 had low energy density and a low 0.3 C discharge capacity.

[0287] Comparing Examples 3-1 to 3-3, good results were obtained in all of Examples 3-1 to 3-3, despite the fact that the coating methods and substrates used in producing the solid electrolyte sheets were different from each other. This indicates that the effects of the technology of the present disclosure can be obtained regardless of the coating method and the type of substrate.

[0288] The reason why the thickness of the solid electrolyte sheet in Comparative Example 3-1 was 90 μm is as follows: Since a solid electrolyte composition (Comparative Example 1-3) containing a solvent with a large polarity term Δp of HSP was used, it was difficult to produce a thin solid electrolyte sheet in Comparative Example 3-1. [Industrial Applicability]

[0289] The solid electrolyte composition of the present disclosure can be used, for example, in the production of all-solid-state lithium-ion secondary batteries. [Explanation of symbols]

[0290] 101 Solid electrolyte 102 Solvent 103 Resin binder 201 Solid electrolyte sheet 202 Electrode 203 Base material 301 Positive electrode 302 Electrolyte layer 303 Negative electrode 1000 solid electrolyte composition 2001 Electrode 2002 Transfer sheet 3000 batteries

Claims

1. A solvent; a solid electrolyte dispersed in the solvent; A solid electrolyte composition comprising: the solid electrolyte composition is a slurry having fluidity, the solid electrolyte includes a halide solid electrolyte, The polarity term δp of the Hansen solubility parameter of the solvent is greater than 0 and less than 5.9; the halide solid electrolyte comprises Li, M1, and X1; M1 is at least one selected from the group consisting of metal elements and metalloid elements other than Li, The solid electrolyte composition, wherein X1 is at least one selected from the group consisting of F, Cl, Br, and I.

2. The solid electrolyte composition according to claim 1, wherein the polar term δp of the Hansen solubility parameter of the solvent is 0.6 or more and 5.7 or less.

3. The halide solid electrolyte is represented by the following composition formula (1): Li α M1 β X1 γ ・・・Form (1) where α, β, and γ are each independently a value greater than 0. The solid electrolyte composition according to claim 1 or 2.

4. The M1 includes yttrium. The solid electrolyte composition according to claim 1 .

5. further comprising a resin binder; The solid electrolyte composition according to claim 1 .

6. The resin binder includes an elastomer. The solid electrolyte composition according to claim 5 .

7. The elastomer contains repeating units derived from styrene. The solid electrolyte composition according to claim 6.

8. Applying the solid electrolyte composition according to any one of claims 1 to 7 to an electrode or a substrate to form a coating film; removing the solvent from the coating film; A method for producing a solid electrolyte sheet, comprising:

9. A method for manufacturing a battery including a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, comprising: providing a solid electrolyte sheet manufactured by the method of claim 8; combining the positive electrode and the negative electrode such that the solid electrolyte sheet is disposed between the positive electrode and the negative electrode as the electrolyte layer; A method for manufacturing a battery, comprising:

10. A solid electrolyte sheet, a halide solid electrolyte; a resin binder attached to the halide solid electrolyte; Including, The thickness of the solid electrolyte sheet is 1 μm or more and 20 μm or less, the arithmetic mean height Sa of the main surface of the solid electrolyte sheet is 0.37 μm or less; Solid electrolyte sheet.

11. the halide solid electrolyte comprises Li, M1, and X1; M1 is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X1 is at least one selected from the group consisting of F, Cl, Br, and I. The solid electrolyte sheet according to claim 10.

12. The maximum height Sz of the main surface of the solid electrolyte sheet is 3.0 μm or more and 7.0 μm or less. The solid electrolyte sheet according to claim 10.

13. A positive electrode and a negative electrode; an electrolyte layer disposed between the positive electrode and the negative electrode; Equipped with The electrolyte layer includes the solid electrolyte sheet according to claim 10. battery.

Images