Composition and method for producing same, dried product and method for producing same, solid electrolyte, and power storage device

Abstract

In the present invention, a composition contains: a charge transfer complex formed from an electron-donating compound and an electron-receiving compound; and a non-aqueous solvent. The electron-donating compound has a phenylene oxide structure. The relative dielectric constant of the non-aqueous solvent is more than 2.0 and less than 40.

Description

Composition and manufacturing method thereof, dried body and manufacturing method thereof, solid electrolyte, and electricity storage device

[0001] [Cross-reference to related applications] This application claims priority to Japanese Patent Application No. 2023-107173, filed on June 29, 2023, the entire contents of which are incorporated herein by reference. The present disclosure relates to a composition and a method for producing the same, a dried body and a method for producing the same, a solid electrolyte, and an electricity storage device.

[0002] Various types of energy storage devices have been put to practical use, including various secondary batteries such as nickel-metal hydride secondary batteries and lithium-ion secondary batteries, as well as electric double-layer capacitors. Among these, lithium-ion secondary batteries are used in a wide range of applications due to their high energy density and battery capacity. In recent years, sodium-ion secondary batteries, potassium-ion secondary batteries, and magnesium-ion secondary batteries have been attracting attention as post-lithium-ion secondary batteries that use elements that replace the rare metal lithium.

[0003] Lithium-ion secondary batteries, which are widely used as energy storage devices, have a negative electrode, a positive electrode, and an electrolyte, and are charged and discharged by transferring lithium ions between the electrodes via the electrolyte. Organic electrolyte solutions have traditionally been used primarily as electrolytes. In recent years, solid or gel electrolytes using inorganic or organic materials have been proposed as a way to eliminate concerns about electrolyte leakage and short circuits within batteries due to overcharge and overdischarge.

[0004] As a solid electrolyte, a composite of a charge transfer complex obtained by doping polyphenylene sulfide, which is in a glassy state at room temperature, with an oxidizing agent and a compound (ionic compound) having an ion source that can serve as a carrier for ion conduction has been developed (see, for example, Patent Document 1).

[0005] US Patent Application Publication No. 2017 / 0005356

[0006] The inventors have found through their investigations that although the solid electrolyte disclosed in Patent Document 1 exhibits relatively high ionic conductivity at room temperature, when the ionic conductivity of the same solid electrolyte is measured multiple times under the same conditions, there is a large variation in the measured values ​​(hereinafter also referred to as "variation in ionic conductivity"). If the ionic conductivity of a solid electrolyte varies widely, there is a concern that secondary batteries manufactured using that solid electrolyte will have unstable battery performance and be inferior in terms of quality assurance.

[0007] The present disclosure has been made in view of the above circumstances, and has as its main object to provide a solid electrolyte that exhibits high ionic conductivity at room temperature and has small variations in ionic conductivity.

[0008] The present inventors have conducted extensive research to solve the above problems and have found that a charge-transfer complex formed by using an electron-donating compound having a phenylene oxide structure, an electron-accepting compound, and a specific solvent can provide a solid electrolyte that exhibits high ionic conductivity at room temperature and has small variability in ionic conductivity.The present disclosure provides the following compositions and methods for producing the same, dried bodies and methods for producing the same, solid electrolytes, and electricity storage devices.

[0009] [1] A composition comprising a charge-transfer complex formed from an electron-donating compound and an electron-accepting compound, and a non-aqueous solvent, wherein the electron-donating compound has a phenylene oxide structure, and the non-aqueous solvent has a relative dielectric constant of more than 2.0 and less than 40.

[0010] [2] The composition according to [1] above, which is for use in a solid electrolyte. [3] The composition according to [1] or [2] above, which has a Gardner color number of 13 or more as measured in accordance with JIS K 0071-2. [4] The composition according to any one of [1] to [3] above, in which the non-aqueous solvent has a relative dielectric constant of 35 or less. [5] The composition according to any one of [1] to [4] above, in which the non-aqueous solvent is a compound having an oxygen atom and / or an aromatic ring structure. [6] The composition according to any one of [1] to [5] above, in which the non-aqueous solvent is at least one selected from the group consisting of a chain ketone, a chain ether, a cyclic ether, a chain carboxylic acid ester, a chain carbonate ester, an aromatic hydrocarbon, and a lactam.

[0011] [7] The composition according to any one of [1] to [6] above, wherein the ratio of the molar amount of the electron-accepting compound to the molar amount of the electron-donating compound (on a monomer basis when the electron-donating compound is a polymer) is 0.1 or more and 1.0 or less. [8] The composition according to any one of [1] to [7] above, wherein the electron-donating compound is a polymer having a repeating unit represented by the following formula (1): (In formula (1), R １ and R ２ are the same or different and represent a hydrogen atom or an alkyl group.) [9] The composition according to any one of the above [1] to [8], wherein the electron-accepting compound comprises at least one selected from the group consisting of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil), 7,7,8,8-tetracyanoquinodimethane (TCNQ), o-benzoquinone, m-benzoquinone, and p-benzoquinone.

[0012]

[10] The composition according to any one of [1] to [9] above, further comprising an alkali metal-containing compound.

[11] The composition according to

[10] above, wherein the alkali metal-containing compound comprises an alkali metal salt.

[12] The composition according to

[10] or

[11] above, wherein the alkali metal-containing compound comprises a lithium-containing compound.

[13] A dried form of the composition according to any one of [1] to [9] above.

[0013]

[14] A dried product according to

[13] above, wherein the dried product is dissolved in a non-aqueous solvent having a dielectric constant of more than 2.0 and less than 40, and the resulting solution has a Gardner color number of 13 or more as measured in accordance with JIS K 0071-2.

[15] A composition comprising the dried product according to

[13] above and an alkali metal-containing compound.

[16] A method for producing the composition according to any of [1] to [9] above, comprising a step of mixing a first solution obtained by dissolving the electron-donor compound in a first solvent with a second solution obtained by dissolving the electron-accepting compound in a second solvent, wherein the first solvent and the second solvent are the same or different and are non-aqueous solvents having a dielectric constant of more than 2.0 and less than 40.

[17] A method for producing a dried body according to the above

[13] , comprising the steps of: mixing a first solution, which is a solution obtained by dissolving the electron-donor compound in a first solvent, with a second solution, which is a solution obtained by dissolving the electron-accepting compound in a second solvent; and removing the non-aqueous solvent from the mixed solution of the first solution and the second solution, wherein the first solvent and the second solvent are the same or different and are non-aqueous solvents having a relative dielectric constant greater than 2.0 and less than 40.

[0014]

[18] A solid electrolyte formed using the composition according to

[10] or

[15] above.

[19] An electricity storage device comprising the solid electrolyte according to

[18] above.

[0015] According to the present disclosure, a solid electrolyte can be obtained that exhibits high ionic conductivity at room temperature and has small ionic conductivity variations. By using such a solid electrolyte as an electrolyte for an electricity storage device such as a secondary battery or a capacitor, it is possible to obtain an electricity storage device that combines safety ensured by the solidification of the electrolyte with battery performance.

[0016] The present disclosure will be described in detail below.

[0017] <Composition> One form of the composition of the present disclosure (hereinafter also referred to as "the composition") is a charge-transfer complex solution containing a charge-transfer complex as component (A) and a non-aqueous solvent as component (B). The component (A) contained in the composition is a charge-transfer complex formed from an electron-donor compound having a phenylene oxide structure and an electron-acceptor compound. The component (B) is a non-aqueous solvent having a relative dielectric constant of greater than 2.0 and less than 40. By using the composition containing such components (A) and (B), a solid electrolyte with excellent ionic conductivity can be obtained. In other words, the composition is suitable for use in solid electrolytes. For convenience, the composition in a solution state containing the component (A) (charge-transfer complex) and the component (B) (non-aqueous solvent) will also be referred to simply as a "charge-transfer complex solution" or "the complex solution."

[0018] Charge-transfer complexes exhibit a deep color due to the strong absorption characteristic of each complex. Therefore, when a charge-transfer complex is formed between an electron-donating compound and an electron-accepting compound, the complex formation appears as a color change. Therefore, the degree of complex formation in the present complex solution can be evaluated by performing a color test on the present composition. For example, in the case of a color test using the Gardner color scale, the higher the Gardner color scale value, the higher the degree of complex formation in the charge-transfer complex solution.

[0019] Specifically, the present complex solution preferably has a Gardner color number of 13 or more as measured in accordance with JIS K 0071-2. When the Gardner color number of the present composition is 13 or more, the degree of complex formation of component (A) in the present complex solution is sufficiently high, and the ionic conductivity of a solid electrolyte obtained using the present complex solution can be further increased. From this perspective, the Gardner color number of the present complex solution is more preferably 14 or more, even more preferably 15 or more, and even more preferably 18 or more. Note that, in this specification, the Gardner color number of a charge-transfer complex solution is a value measured for a solution in which the total amount of the electron-donor compound and the electron-acceptor compound is 20 mass% relative to the total amount of the charge-transfer complex solution. The Gardner color number is measured in accordance with the method described in the Examples below.

[0020] <Component (A): Charge-Transfer Complex> Electron-Donor Compound The electron-donor compound constituting component (A) has a phenylene oxide structure. A molecule having a phenylene oxide structure (hereinafter also referred to as "phenylene oxide") is represented by the general formula: -(C ６ R ４ -O) ｎ - (wherein R is the same or different and is a hydrogen atom or an alkyl group, and n is an integer of 1 or more). When R is an alkyl group, the number of carbon atoms in the alkyl group is preferably 1 or 2, and more preferably 1. n is, for example, 1 to 600.

[0021] Specific examples of phenylene oxides when n in the above general formula is 1 include 2,6-dimethyl-1,4-phenylene oxide and 2,5-dimethyl-1,4-phenylene oxide. When n is 2 or more (hereinafter also referred to as "polyphenylene oxide"), examples of phenylene oxides include those represented by the general formula: -(C ６ R ４ -O) ｎ Among these, the electron donor compound is preferably polyphenylene oxide, and a polymer having a repeating unit represented by the following formula (1) is particularly preferred, in that it can increase the ionic conductivity of the solid electrolyte and can provide a solid electrolyte having excellent mechanical strength, durability, and heat resistance: (In formula (1), R １ and R ２ are the same or different and each represents a hydrogen atom or an alkyl group.

[0022] When the electron donating compound is a polyphenylene oxide having a repeating unit represented by the above formula (1), from the viewpoint of increasing the electron donating property of the polyphenylene oxide and promoting the formation of a complex with the electron accepting compound, R １ and R ２ is preferably an alkyl group. １ and R ２ From the viewpoint of availability of materials, is preferably a methyl group or an ethyl group, and more preferably a methyl group.

[0023] The number average molecular weight of polyphenylene oxide is, for example, 500 to 30,000, preferably 500 to 20,000, more preferably 1,000 to 20,000, even more preferably 1,000 to 15,000, and still more preferably 1,000 to 10,000. Polyphenylene oxide is commercially available from, for example, SABIC Corporation. The electron donor compound may be used alone or in combination of two or more.

[0024] Electron-Accepting Compound The electron-accepting compound may be any compound capable of forming a charge-transfer complex with the electron-donating compound. Specific examples of electron-accepting compounds include quinones, cyanides, oxygen, ozone, iodine, sulfur trioxide, and transition metal oxides (e.g., manganese dioxide). Specific examples of quinones include 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), o-benzoquinone, m-benzoquinone, and p-benzoquinone. Specific examples of cyanides include 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE). The electron-accepting compound may be used alone or in combination of two or more.

[0025] Among the above, the electron-accepting compound preferably includes at least one selected from the group consisting of quinones and cyanides, in that it is easy to form a charge-transfer complex with phenylene oxide and can provide a solid electrolyte with high ionic conductivity. Among these, it is particularly preferable to include at least one selected from the group consisting of 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ), o-benzoquinone, m-benzoquinone, and p-benzoquinone.

[0026] In component (A), the ratio of the molar amount of the electron-accepting compound to the molar amount of the electron-donating compound (on a monomer basis when the electron-donating compound is a polymer) (hereinafter also referred to as "(molar amount of electron-accepting compound) / (molar amount of electron-donating compound)") is preferably 0.1 or more and 1.0 or less. By setting the ratio (molar amount of electron-accepting compound) / (molar amount of electron-donating compound) within the above range, a solid electrolyte with superior ionic conductivity can be obtained. From this perspective, the ratio (molar amount of electron-accepting compound) / (molar amount of electron-donating compound) is more preferably 0.15 or more, even more preferably 0.2 or more, and even more preferably 0.25 or more. The upper limit of the ratio (molar amount of electron-accepting compound) / (molar amount of electron-donating compound) is more preferably 0.9 or less, even more preferably 0.8 or less, and even more preferably 0.7 or less.

[0027] <Component (B): Non-aqueous solvent> The relative dielectric constant (ε ｒ ) is more than 2.0 and less than 40. If the relative dielectric constant of the non-aqueous solvent is 2.0 or less or 40 or more, the degree of complex formation of component (A) is low, and when a solid electrolyte is produced, the ionic conductivity is poor. From the viewpoint of increasing the degree of complex formation of component (A) and obtaining a solid electrolyte with high ionic conductivity, the dielectric constant of the non-aqueous solvent is preferably 35 or less, more preferably 30 or less, and even more preferably 20 or less. The lower limit of the dielectric constant of the non-aqueous solvent is preferably 3 or more, more preferably 5 or more.

[0028] In this specification, the relative dielectric constant of the non-aqueous solvent is the value described in "Chemical Handbook: Basics," 5th revised edition, edited by the Chemical Society of Japan (Maruzen Co., Ltd.). The non-aqueous solvent may be used singly or in combination of two or more. When a mixed solvent of two or more non-aqueous solvents is used, the relative dielectric constant (ε ｒｍｉｘ ) is a value calculated by Wiener's limit formula shown in the following formula (1). ｒｍｉｘ = ε ｒ２ + (ε ｒ１ -ε ｒ２ ) Φ １ (1) In equation (1), ε ｒｍｉｘ: relative dielectric constant of mixed solvent ε ｒ１ : relative dielectric constant of solvent 1 ε ｒ２ : relative dielectric constant of solvent 2 Φ １ : Volume ratio of solvent 1

[0029] The non-aqueous solvent used as component (B) is not particularly limited as long as it has a relative dielectric constant greater than 2.0 and less than 40. Specific examples of non-aqueous solvents include at least one compound selected from the group consisting of hydrocarbons, alcohol compounds, ether compounds, ketone compounds, ester compounds, amide compounds, and nitrile compounds, which has a relative dielectric constant greater than 2.0 and less than 40.

[0030] Specific examples of these include hydrocarbons such as cyclohexane and toluene, and alcohol compounds such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, isopentyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 2-methoxyethanol, 2-ethoxyethanol, diethylene glycol, and triethylene glycol.

[0031] Examples of ether compounds include diethyl ether, diisopropyl ether, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, anisole, 1,2-dimethoxyethane, etc. Examples of ketone compounds include acetone, 2-butanone, cyclohexanone, etc.

[0032] Examples of ester compounds include ethyl acetate, butyl acetate, γ-butyrolactone, etc. Examples of amide compounds include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, hexamethylphosphoric triamide, etc. Examples of nitrile compounds include acetonitrile, propionitrile, benzonitrile, etc.

[0033] In terms of being able to obtain a solid electrolyte with high ion conductivity, the nonaqueous solvent is preferably a compound having an oxygen atom and / or an aromatic ring structure and having a relative dielectric constant of more than 2.0 and less than 40. Among these, a compound having a relative dielectric constant of 35 or less is more preferred, and a compound having a relative dielectric constant of 30 or less is even more preferred.

[0034] The non-aqueous solvent is preferably at least one selected from the group consisting of ketone compounds, ether compounds, ester compounds, amide compounds, and hydrocarbons, and more preferably at least one compound selected from the group consisting of chain ketones, chain ethers, cyclic ethers, chain carboxylic acid esters, chain carbonate esters, aromatic hydrocarbons, cyclic esters, and cyclic amides, in that a solid electrolyte having high ionic conductivity and small variation in ionic conductivity can be obtained.

[0035] Among these, the nonaqueous solvent is preferably at least one compound selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), a compound represented by the following formula (4), and a compound represented by the following formula (5), and the compound has a relative dielectric constant of more than 2.0 and less than 40. (In formula (2), R ３ are the same or different and are alkyl groups, or two R ３ represents a cyclic structure formed by bonding (In formula (3), X １ represents —CO—, —CO—O—, or —O—CO—O—. ４ are the same or different and each represents an alkyl group. (In formula (4), R ５ are the same or different and each represents a hydrogen atom or an alkyl group. (In formula (5), X ２ is -NR ６ - or -O-. ６ is a hydrogen atom or an alkyl group, and n is 2 to 4.

[0036] In the compounds represented by the above formulas (2) to (5), R ３ , R ４ , R ５ and R ６When is an alkyl group, examples of the alkyl group include a methyl group, an ethyl group, a 1-propyl group, a 2-propyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group.

[0037] The boiling point of the non-aqueous solvent is not particularly limited, but is preferably 50° C. or higher from the viewpoint of suppressing volatilization of the non-aqueous solvent during the production process, etc. Furthermore, the boiling point of the non-aqueous solvent is preferably 200° C. or lower, more preferably 180° C. or lower, and even more preferably 150° C. or lower, from the viewpoint of enabling desolvation of the solution of the complex by a simple operation (for example, heating at the lowest possible temperature). The boiling point indicates a value under atmospheric pressure.

[0038] The content of the nonaqueous solvent in the present complex solution is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more, based on the total amount of the charge-transfer complex solution, from the viewpoint of obtaining a solid electrolyte having high ionic conductivity at room temperature and small variability in ionic conductivity, and the content of the nonaqueous solvent is preferably 99% by mass or less, more preferably 90% by mass or less, based on the total amount of the charge-transfer complex solution.

[0039] <Other Components> The present complex solution may further contain components (hereinafter also referred to as "other components") different from the above-described component (A) and component (B) to the extent that the effects of the present disclosure are not impaired. Examples of other components include a non-aqueous solvent different from component (B), water, a binder, etc. When the present composition contains a non-aqueous solvent different from component (B) and / or water as other components, the total content of the non-aqueous solvent different from component (B) and / or water is, for example, 0.5 mass% or less, and preferably 0.1 mass% or less, relative to the mass of component (B).

[0040] <Method for producing charge-transfer complex solution> The present complex solution can be produced by a method (hereinafter also referred to as "the present production method") that includes a step of mixing a first solution, which is a solution obtained by dissolving phenylene oxide, an electron-donor compound, in a first solvent, with a second solution, which is a solution obtained by dissolving, in a second solvent, an electron-accepting compound, which is a compound capable of forming a charge-transfer complex with phenylene oxide.

[0041] From the viewpoint of increasing the degree of complex formation between phenylene oxide and the electron-accepting compound, the first solvent and the second solvent are preferably non-aqueous solvents having a relative dielectric constant of more than 2.0 and less than 40. Examples of non-aqueous solvents having a relative dielectric constant of more than 2.0 and less than 40 include the above-described component (B). The first solvent and the second solvent may be the same or different. In consideration of preventing a decrease in the degree of complex formation and ease of operation, it is preferable that the first solvent and the second solvent are the same, or, if the first solvent and the second solvent are different, they are compatible with each other.

[0042] The content of the electron donor compound in the first solution and the content of the electron acceptor compound in the second solution are each, for example, 0.05 to 60% by mass. From the viewpoint of efficiently removing the solvent when removing it from the solution, the content of the electron donor compound in the first solution and the content of the electron acceptor compound in the second solution are each preferably 1% by mass or more, more preferably 10% by mass or more. Furthermore, from the viewpoint of obtaining a mixed solution in which the electron donor compound and the electron acceptor compound are uniformly mixed, the upper limit of the content is preferably 55% by mass or less, more preferably 50% by mass or less.

[0043] The method for mixing the first solution and the second solution is not particularly limited, and any appropriate method can be used. For example, one of the first solution and the second solution may be added to the other, or the first solution and the second solution may be added simultaneously to a predetermined container. The first solution and the second solution may be added all at once or in portions. Furthermore, in order to uniformly mix the first solution and the second solution, the mixture of the first solution and the second solution may be appropriately subjected to a process such as stirring.

[0044] When mixing the first solution and the second solution, it is preferable to adjust the concentrations and amounts of the first solution and the second solution so that the ratio of the molar amount of the electron-accepting compound to the molar amount of the electron-donor compound (in terms of monomers when the electron-donor compound is a polymer) ([molar amount of electron-accepting compound] / [molar amount of electron-donor compound]) is 0.1 or more and 1.0 or less. [Molar amount of electron-accepting compound] / [molar amount of electron-donor compound] is more preferably 0.15 or more, even more preferably 0.2 or more, and even more preferably 0.25 or more. The upper limit of [molar amount of electron-accepting compound] / [molar amount of electron-donor compound] is more preferably 0.9 or less, even more preferably 0.8 or less, and even more preferably 0.7 or less.

[0045] It is not necessary for all of the electron donor compounds and electron acceptor compounds contained in the mixture of the first solution and the second solution to form a charge-transfer complex, and the complex solution may contain an electron donor compound and / or an electron acceptor compound. However, from the viewpoint of obtaining a solid electrolyte that exhibits high ionic conductivity and has small variability in ionic conductivity, it is preferable that the amount of the electron donor compound and / or the electron acceptor compound contained in the charge-transfer complex solution is as small as possible, that is, it is preferable that the degree of complex formation of the charge-transfer complex obtained using the electron donor compound and the electron acceptor compound as raw materials is high.

[0046] For specific examples and content ratios of components other than component (B) that may be contained in the mixed solution of the first solution and the second solution, the explanation for the other components that may be contained in the present complex solution applies.

[0047] According to this production method, the electron donor compound and the electron acceptor compound are mixed in solution, which allows for a more uniform mixture of the electron donor compound and the electron acceptor compound than dry blending. Therefore, the solid electrolyte obtained using this complex solution has a uniform composition, which is believed to have increased ionic conductivity at room temperature while reducing ionic conductivity variation. Furthermore, the use of component (B) as a solvent in forming a charge-transfer complex between the electron donor compound phenylene oxide and the electron acceptor compound increases the degree of complex formation of the charge-transfer complex, which is believed to have resulted in a solid electrolyte with high ionic conductivity at room temperature.

[0048] <Dried product> The dried product of the present complex solution (hereinafter also referred to as "the present dried product") is obtained by removing the solvent from the above-mentioned charge-transfer complex solution.

[0049] <Method for Producing the Dried Product> The dried product can be obtained by a method including the step of removing the non-aqueous solvent from the mixture of the first solution and the second solution in the method for producing the present composition described above.

[0050] There are no particular limitations on the method for removing the solvent from the mixture of the first solution and the second solution, and the method can be carried out by appropriately adopting a known desolvation method. For example, desolvation may be carried out by heating, or by appropriately combining one or more of natural drying, air blowing, freeze-drying, and the like. When removing the non-aqueous solvent by heating, the heating temperature can be appropriately set depending on the type of non-aqueous solvent, but can be, for example, 80 to less than 150°C. The heating time is, for example, 30 minutes to 2 hours. The desolvation process may be carried out under atmospheric pressure or under reduced pressure. When a non-aqueous solvent with a boiling point of 150°C or higher is used as the first solvent and / or the second solvent, the desolvation process is preferably carried out under reduced pressure and at a heating temperature of less than 150°C.

[0051] In this specification, the term "dry" refers to a state in which the nonaqueous solvent is completely removed, as well as a state in which the nonaqueous solvent remains during the drying process. The nonaqueous solvent content of the dried product obtained by the drying treatment is, for example, 10% by mass or less, and preferably 5% by mass or less.

[0052] <Characteristics of the Dried Body> The dried body obtained as described above is dissolved in a non-aqueous solvent having a dielectric constant of more than 2.0 and less than 40, and the Gardner color number measured in accordance with JIS K 0071-2 is preferably 13 or more, more preferably 14 or more, even more preferably 15 or more, and even more preferably 18 or more. When the Gardner color number of a solution obtained by dissolving the dried body in the non-aqueous solvent (hereinafter also referred to as the "dried body solution") is within the above range, the degree of complex formation of component (A) in the dried body is sufficiently high, and the ionic conductivity of a solid electrolyte obtained using the dried body can be further improved. Note that, in this specification, the Gardner color number of the dried body solution is a value measured for a solution in which the content of the dried body is 20 mass% relative to the total amount of the dried body solution. The Gardner color number is measured in accordance with the method described in the Examples below. Examples of non-aqueous solvents having a dielectric constant of more than 2.0 and less than 40 include the compounds described above as component (B).

[0053] <Electrolyte-forming composition> Another form of the present composition is a composition (hereinafter also referred to as "electrolyte-forming composition") containing the charge-transfer complex solution or its dried form according to the present disclosure and an alkali metal-containing compound. The electrolyte-forming composition can provide a solid electrolyte that exhibits high ionic conductivity at room temperature and has small variation in ionic conductivity.

[0054] <Component (C): Alkali Metal-Containing Compound> The alkali metal-containing compound is not particularly limited as long as it is a compound that generates alkali metal ions. Specific examples of the alkali metal-containing compound include lithium-containing compounds, sodium-containing compounds, and potassium-containing compounds. Among these, lithium-containing compounds and sodium-containing compounds are preferred, and lithium-containing compounds are more preferred, in that they can improve the ionic conductivity of the solid electrolyte.

[0055] Examples of alkali metal-containing compounds include oxides of alkali metals, hydroxides of alkali metals, and salts of alkali metals. Specific examples of these include oxides of alkali metals such as lithium oxide, sodium oxide, and potassium oxide. Hydroxides of alkali metals include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of alkali metal salts include Li. ２ CO ３ , LiBr, LiCl, LiI, LiSCN, LiBF ４ , LiAsF ６ , LiClO ４ , C.H. ３ COOLi, CF ３ COOLi, LiCF ３ SO ３ , LiPF ６ , LiC(CF ３ SO ２ ) ３ , lithium bis(fluorosulfonyl)imide (Li ＋ (FSO ２ ) ２ N － ), lithium bis(trifluoromethanesulfonyl)imide (Li ＋ (CF ３ SO ２ ) ２ N － and lithium salts such as lithium (fluorosulfonyl) (trifluoromethanesulfonyl) imide; and salts of the anions of these lithium salts with alkali metals other than lithium (for example, sodium and potassium).

[0056] Among the above-mentioned alkali metal-containing compounds, alkali metal salts are preferred, lithium salts or sodium salts are more preferred, and lithium salts are even more preferred, in terms of the ability to obtain solid electrolytes with small variations in ionic conductivity. Furthermore, among the lithium salts, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide are particularly preferred in terms of high ionic dissociation.

[0057] In the electrolyte-forming composition, the amount of the alkali metal-containing compound is preferably such that the ratio of the alkali metal-containing compound to the total molar amount of the electron donor compound (when the electron donor compound is a polymer, the amounts are calculated on a monomer basis) and the electron acceptor compound, which are the supply components of component (A), ([molar amount of component (C)] / [molar amount of electron donor compound + molar amount of electron acceptor compound]) is 0.03 or more and 1.0 or less. By having [molar amount of component (C)] / [molar amount of electron donor compound + molar amount of electron acceptor compound] in the above range, a solid electrolyte exhibiting better ion conductivity can be obtained. From this perspective, [molar amount of component (C)] / [molar amount of electron donor compound + molar amount of electron acceptor compound] is more preferably 0.05 or more, even more preferably 0.1 or more, even more preferably 0.2 or more, and even more preferably 0.3 or more. The upper limit of [molar amount of component (C)] / [molar amount of electron donor compound + molar amount of electron acceptor compound] is more preferably 0.9 or less, even more preferably 0.8 or less, even more preferably 0.7 or less, and even more preferably 0.6 or less. The alkali metal-containing compounds may be used alone or in combination of two or more.

[0058] The electrolyte-forming composition can be obtained by mixing the present complex solution or its dried form with the component (C). When the present complex solution or its dried form is mixed with the component (C), the component (C) may be in any state, such as a solid, a molten liquid, or a solution in which the component (C) is dissolved in a solvent. Examples of the solvent that dissolves the component (C) include the non-aqueous solvents exemplified above as the component (B).

[0059] The method for mixing the present complex solution or its dried form with component (C) is not particularly limited, and can be performed using any appropriate method. For example, component (C) may be added to the present complex solution or its dried form, or the present complex solution or its dried form and component (C) may be added simultaneously to a predetermined container. The present complex solution or its dried form and component (C) may be added all at once or in portions. Furthermore, for the purpose of uniformly mixing the present complex solution or its dried form with component (C), a treatment such as stirring may be appropriately performed on the mixture of the present complex solution or its dried form and component (C).

[0060] The complex solution or its dried form may be mixed with the component (C) by either a dry method or a wet method. Furthermore, heating may be performed when mixing the complex solution or its dried form with the component (C). For example, a grinding treatment may be performed in addition to the heating treatment when mixing the dried complex solution with the component (C), thereby obtaining an electrolyte-forming composition. When grinding and heating the dried complex solution and the component (C), the heat treatment may be performed after grinding the dried complex solution and the component (C), or the grinding treatment may be performed after heating the dried complex solution and the component (C). The method for grinding the dried complex solution and the component (C) is not particularly limited, but is preferably performed using a grinder such as a ball mill, a bead mill, or a blender. The grinding treatment to obtain the electrolyte-forming composition may be performed once or multiple times. The temperature at which the dried complex solution and the component (C) are heated is typically 100 to 300°C, preferably 100 to 250°C. The heating time is, for example, 5 to 30 minutes.

[0061] <Solid Electrolyte> The solid electrolyte of the present disclosure (hereinafter also referred to as "the present solid electrolyte") is a solid electrolyte formed from a composition containing the present complex solution or a dried form thereof and the component (C).

[0062] <Method for Producing Solid Electrolyte> The method for producing the present solid electrolyte is not particularly limited. A preferred embodiment of the method for producing the present solid electrolyte is the following method.

[0063] When the present solid electrolyte is produced using a composition containing the present complex solution and component (C), the composition is first placed in a container and the solvent is removed by heating or other treatment. This results in a solid product of the desired shape. When the present solid electrolyte is produced using a composition containing a dried form of the present complex solution and component (C), the composition is molded into the desired shape. The molding method for the present composition is not particularly limited, and known methods such as extrusion molding, injection molding, pressure molding, slip casting, mold casting, and tape casting can be used. Of these, it is preferable to obtain a molded product by pressure molding of the present composition. The shape of the molded product is not particularly limited and can be appropriately set depending on the shape of the applied power storage device. The shape of the molded product is, for example, rectangular or circular.

[0064] Subsequently, the solid or compact is preferably heated at a temperature equal to or higher than the melting point of the alkali metal-containing compound. This heat treatment (annealing treatment) relieves residual stress, thereby stabilizing the dimensional accuracy of the solid electrolyte and suppressing deformation such as distortion and cracking. The temperature during the annealing treatment is preferably higher than the melting point of the alkali metal-containing compound. The annealing time is, for example, 1 to 24 hours, preferably 2 to 24 hours.

[0065] After heating, the temperature of the solid electrolyte may be lowered by rapidly cooling the solid electrolyte (for example, by placing the solid electrolyte in a thermostatic bath at a low temperature (for example, 25°C or less) for about 2 hours or less), or by gradually cooling the solid electrolyte (for example, by slowly cooling to room temperature over 3 to 48 hours). From the viewpoint of suppressing crystallization of the alkali metal-containing compound, the temperature of the solid electrolyte is preferably lowered by the former method (rapid cooling). When the temperature of the solid electrolyte is lowered by rapid cooling, if the solid electrolyte is cooled by placing it in a thermostatic bath, the temperature of the thermostatic bath is preferably 0°C or lower, and more preferably -15°C or lower.

[0066] <Characteristics of the solid electrolyte> The present solid electrolyte exhibits high ionic conductivity at room temperature. Specifically, for a solid electrolyte having a thickness of about 300 μm (more specifically, 300±30 μm), the ionic conductivity measured at 25° C. using an AC impedance method is 3×10 －７ S.cm. －１ From the viewpoint of obtaining an electricity storage device with excellent performance, the ionic conductivity under the same conditions is preferably 5×10 or more. －7 S.cm. －１ More preferably, it is 8×10 or more. －7 S.cm. －１ More preferably, the above is the case. Details of the method for measuring ionic conductivity follow the method described in the Examples below. In this specification, the variation in ionic conductivity refers to the phenomenon in which, when the ionic conductivity of the same solid electrolyte is measured multiple times under the same conditions, the measured values ​​do not match between measurements and are distributed irregularly.

[0067] This solid electrolyte exhibits high ionic conductivity at room temperature with little variation in ionic conductivity, and therefore, by using this solid electrolyte as the electrolyte in an electricity storage device, electricity storage devices of stable quality can be obtained.

[0068] <Electricity Storage Device> The electricity storage device of the present disclosure (hereinafter also referred to as "the device") includes the solid electrolyte. Examples of the device include a secondary battery, a capacitor, etc. When the device is a secondary battery, one embodiment is an all-solid-state battery, and a lithium-ion secondary battery is preferred because of its excellent ionic conductivity.

[0069] An all-solid-state lithium-ion secondary battery, which is one embodiment of the device, will now be described. A lithium-ion secondary battery is a laminate comprising electrodes consisting of a positive electrode and a negative electrode, and a solid electrolyte, with the solid electrolyte being disposed between the positive electrode and the negative electrode so that the solid electrolyte is in contact with the electrode. The materials constituting the positive electrode and the negative electrode are not particularly limited, and can be appropriately selected from materials known as electrode materials for lithium-ion secondary batteries. For example, a metal foil such as aluminum or stainless steel can be used as the positive electrode current collector. A metal foil such as copper foil or lithium foil can be used as the negative electrode current collector.

[0070] In the lithium-ion secondary battery of the present disclosure, the solid electrolyte contains the above-described component (A) and component (C). The thickness of the solid electrolyte is not particularly limited and can be appropriately set depending on the application of the secondary battery, etc. The thickness of the solid electrolyte is, for example, 5 to 500 μm.

[0071] The method for producing a lithium ion secondary battery is not particularly limited, and known methods can be appropriately adopted depending on the battery structure, etc. For example, a laminate including a positive electrode, a solid electrolyte, and a negative electrode may be produced by sandwiching a solid electrolyte obtained by annealing a molded body of the present composition between a positive electrode and a negative electrode. Alternatively, a laminate including a positive electrode, a solid electrolyte, and a negative electrode may be produced by placing the present composition between a positive electrode and a negative electrode in a container and then annealing the container. A laminate including a positive electrode, a solid electrolyte, and a negative electrode is usually placed in a case and used as a secondary battery.

[0072] The device is not limited to the above-described configuration in which the carrier for ion conduction is lithium ions, and may be a secondary battery in which other ions, such as sodium ions, are used as carriers. The device may also be a capacitor. One embodiment of the capacitor includes an anode body, a cathode body, and a solid electrolyte, with the solid electrolyte disposed between the anode body and the cathode body so that the solid electrolyte is in contact with the electrode.

[0073] The power storage device including the solid electrolyte can be used for a variety of purposes, specifically as a power source for various mobile devices such as mobile phones, personal computers, smartphones, game consoles, and wearable devices; various moving objects such as electric vehicles, hybrid vehicles, robots, and drones; and various electric and electronic devices such as digital cameras, video cameras, music players, power tools, and home appliances.

[0074] The present disclosure will be specifically described below based on examples. However, the present disclosure is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0075] Example 1 (Preparation of Charge-Transfer Complex Solution) Poly(2,6-dimethyl-1,4-phenylene oxide) (SA90 manufactured by SABIC, hereinafter also referred to as "SA90") (100 mg) was added to 2-butanone (hereinafter also referred to as "MEK") to make a 20 mass % solution. 2,3-Dichloro-5,6-dicyano-p-benzoquinone (hereinafter also referred to as "DDQ") (47 mg) was added to MEK to make a 20 mass % solution. The obtained MEK mixed solution of SA90 and MEK mixed solution of DDQ were mixed to obtain charge-transfer complex solution DE-1 as a composition for a solid electrolyte.

[0076] (Measurement of Gardner Color Number of Charge-Transfer Complex Solution) In accordance with JIS K 0071-2:1998, the degree of complex formation of the charge-transfer complex solution was evaluated by visually comparing the charge-transfer complex solution with a Gardner color number standard solution. As a result, the Gardner color number of the charge-transfer complex solution DE-1 was "18+." Here, the Gardner color number was measured by using the charge-transfer complex solution as a sample, and the Gardner color number of the standard solution when the color of this sample matched that of the Gardner color number standard solution. Note that if the color of the sample did not match that of the Gardner color number standard solution, the Gardner color number that most closely matched the sample was determined, and cases where the color number was lighter than the determined color number were represented as "-," and cases where the color number was darker than the determined color number were represented as "+." In general, charge-transfer complexes have a unique strong absorption called the charge-transfer absorption band and exhibit a dark color. Therefore, the larger the Gardner color number of a charge-transfer complex solution, the higher the degree of complex formation.

[0077] (Production of Electrolyte-Forming Composition) Subsequently, a 20 mass % MEK solution of lithium (fluorosulfonyl) (trifluoromethanesulfonyl) imide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.; trade name (fluorosulfonyl) (trifluoromethanesulfonyl) imide = lithium, hereinafter also referred to as "LiFTFSI") (63 mg) was added to the charge-transfer complex solution obtained above, thereby obtaining a 20 mass % electrolyte-forming composition CE-1 as a composition for forming a solid electrolyte.

[0078] (Production of solid electrolyte) 240 mg of the electrolyte-forming composition CE-1 was filled into three sets of all-solid-state battery evaluation cells (KP-SolidCell manufactured by Hosen Co., Ltd.), dried at 100°C for 1 hour, and then sealed with a torque of 20 N m. SKD steel discs (diameter 1 cm) were used to sandwich the dried electrolyte-forming composition CE-1. The evaluation cell was heated (annealed) for 10 hours on a hot plate set at 110°C. Then, it was cooled at 25°C for 2 hours to obtain solid electrolyte SE-1.

[0079] (Measurement of ionic conductivity) For measurement, an AC impedance method was used in which an AC voltage (applied voltage of 100 mV) is applied between electrodes to measure the resistance component, and the ionic conductivity was calculated from the real impedance intercept of the obtained Cole-Cole plot. The measurement was performed using an impedance analyzer (SP-300 manufactured by Biologic) at 25°C. All of the above operations were performed in a dry room with a dew point of -60°C. The ionic conductivity (σ) was calculated using the following formula (2), and was found to be 5×10 －５ S.cm. －１ , 1×10 －５ S.cm. －１ , 5 x 10 －５ S.cm. －１ The ionic conductivity (σ) in Table 1 is the highest value of three measurements. σ=H / (R×S) (2) (In formula (2), σ is the ionic conductivity (unit: S cm －１ ), R is the resistance (unit: Ω), S is the cross-sectional area of ​​the solid electrolyte membrane at the time of measurement (unit: cm ２ ), H indicates the distance between the electrodes (unit: cm).

[0080] The value calculated from the three measurements of the ionic conductivity using the following formula (3) was evaluated based on the following criteria, and was judged to be "A." Note that A and B below mean that the variation in ionic conductivity is small and within an acceptable range, and C means that the variation in ionic conductivity is large to an unacceptable extent. s = σ(MAX) / σ(MIN) (3) (In formula (3), σ(MAX) is the ionic conductivity (unit: S cm －１) indicates the maximum value of the measured value, and σ(MIN) indicates the minimum value of the measured value.) A: s is less than 100 B: s is 100 or more but less than 1,000 C: s is 1,000 or more

[0081] The evaluation results of the solid electrolyte SE-1 are shown in Table 1. In Table 1, "molar ratio (electron-accepting compound) / (electron-donor compound)" represents the ratio of the molar amount of the electron-accepting compound to the molar amount of the electron-donor compound (in terms of monomer). "molar ratio (C) / [(electron-donor compound)+(electron-accepting compound)]" represents the ratio of the molar amount of the component (C) to the total amount of the molar amount of the electron-accepting compound (in terms of monomer) and the molar amount of the electron-donor compound.

[0082] Examples 2 to 10 and Comparative Examples 1 and 2 Charge-transfer complex solutions DE-2 to DE-12, electrolyte-forming compositions CE-2 to CE-12, and solid electrolytes SE-2 to SE-12 were obtained by the same procedure as in Example 1, except that the types and amounts of raw materials were changed as shown in Table 1. The Gardner color index of the charge-transfer complex solutions DE-2 to DE-12 and the ionic conductivity and variation thereof of the solid electrolytes SE-2 to SE-12 were measured by the same procedure as in Example 1. The results are shown in Table 1.

[0083]

[0084] Details of the compounds used in Table 1 are shown below. The relative dielectric constants of the non-aqueous solvents (component (B)) shown in Table 1 were quoted from the values ​​given in "Revised 5th Edition Chemistry Handbook, Basics I" edited by the Chemical Society of Japan (Maruzen Co., Ltd.). SA90: hydroxyl-terminated poly(2,6-dimethyl-1,4-phenylene oxide) [manufactured by SABIC, R in formula (1)] １ and R ２ are all methyl groups, number average molecular weight 1,600] SA9000: poly(2,6-dimethyl-1,4-phenylene oxide) having a terminal methacryloyl group (manufactured by SABIC, R in formula (1) １ and R ２are methyl groups, number average molecular weight 2,300)] DDQ: 2,3-dichloro-5,6-dicyano-p-benzoquinone [Fujifilm Wako Pure Chemical Industries, Ltd.] Chloranil: 2,3,5,6-tetrachloro-1,4-benzoquinone [Fujifilm Wako Pure Chemical Industries, Ltd.] TCNQ: 7,7,8,8-tetracyanoquinodimethane [Fujifilm Wako Pure Chemical Industries, Ltd.] BQ: p-benzoquinone [Fujifilm Wako Pure Chemical Industries, Ltd.] LiFTFSI: lithium (fluorosulfonyl) (trifluoromethanesulfonyl) imide [Fujifilm Wako Pure Chemical Industries, Ltd., trade name (fluorosulfonyl) (trifluoromethanesulfonyl) imide = lithium] LiTFSI: lithium bis(trifluoromethanesulfonyl) imide [Fujifilm Wako Pure Chemical Industries, Ltd.] LiFSI: Lithium bis(fluorosulfonyl)imide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) NaFSI: Sodium bis(fluorosulfonyl)imide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) MEK: 2-butanone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) THF: Tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) NMP: N-methyl-2-pyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) DMF: Dimethylformamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) DMSO: Dimethyl sulfoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0085] Example 11 The charge transfer complex solution DE-1 obtained in Example 1 was heated at 100°C for 1 hour to remove MEK, and a dried product was obtained. The dried product obtained above was dissolved in MEK to a concentration of 20% by mass, and the Gardner color score of the resulting solution measured in accordance with JIS K 0071-2:1998 was "18+". The dried product (147 mg) and LiFTFSI (63 mg) were ground using a ball mill (a mini mill PULVERISETTE 23 manufactured by FRITSCH; hereinafter, also referred to simply as "ball mill") at a frequency of 40 Hz for 60 minutes, and then heated on a hot plate set at 150°C for 10 minutes to melt the LiFTFSI. After cooling, the mixture was ground using a ball mill at 40 Hz for 60 minutes to obtain a solid electrolyte powder (referred to as electrolyte-forming composition CE-13). Furthermore, 30 mg of the electrolyte-forming composition CE-13 was filled into each of three sets of all-solid-state battery evaluation cells (KP-SolidCell manufactured by Hosen Co., Ltd.), and the cells were sealed with a torque of 20 N m. SKD steel discs (diameter 1 cm) were used to sandwich the electrolyte-forming composition CE-13. The evaluation cells were heated (annealed) for 10 hours on a hot plate set at 110°C. Thereafter, the cells were cooled at 25°C for 2 hours to obtain solid electrolyte SE-13. The ionic conductivity of solid electrolyte SE-13 was measured using the same procedure as in Example 1, and the ionic conductivity was found to be 4 x 10 －５ S.cm. －１ (the highest value of the results of three measurements), and the variation in ionic conductivity was judged to be "A."

[0086] [Evaluation Results] As is clear from the results of Examples 1 to 11, the compositions of the present disclosure have a high degree of complex formation, and the solid electrolytes obtained from these compositions exhibit high ionic conductivity even at room temperature, with little variation in the values.

[0087] Among these, focusing on the relative dielectric constant of the non-aqueous solvent, when Examples 1 to 5 and 11 are compared with Example 6, better ionic conductivity was exhibited when the relative dielectric constant was 35 or less (Examples 1 to 5 and 11).

[0088] The above results demonstrate that a solid electrolyte obtained from the composition of the present disclosure, which contains a charge-transfer complex formed from an electron-donor compound having a phenylene oxide structure and an electron-acceptor compound, and a non-aqueous solvent, wherein the non-aqueous solvent has a relative dielectric constant of more than 2.0 and less than 40, exhibits high ionic conductivity at room temperature and has small variation in ionic conductivity.

[0089] The present invention is not limited to the above-described embodiments, and encompasses various modifications and equivalent modifications within the scope of the spirit of the present invention. Therefore, in light of the above teachings, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are to be understood as falling within the scope and spirit of the present invention.

Claims

1. A composition comprising: a charge transfer complex formed from an electron donor compound and an electron accepting compound; and a non-aqueous solvent, wherein the electron donor compound has a phenylene oxide structure; and the non-aqueous solvent has a relative dielectric constant of more than 2.0 and less than 40.

2. The composition according to claim 1, which is for use as a solid electrolyte.

3. The composition according to claim 1, which has a Gardner color number of 13 or more as measured in accordance with JIS K 0071-2.

4. The composition according to claim 1, wherein the non-aqueous solvent has a relative dielectric constant of 35 or less.

5. The composition according to claim 1, wherein the non-aqueous solvent is a compound having an oxygen atom and / or an aromatic ring structure.

6. The composition according to claim 1, wherein the non-aqueous solvent is at least one selected from the group consisting of chain ketones, chain ethers, cyclic ethers, chain carboxylates, chain carbonates, aromatic hydrocarbons, and lactams.

7. The composition according to claim 1, wherein the ratio of the molar amount of the electron-accepting compound to the molar amount of the electron-donating compound (converted to a monomer when the electron-donating compound is a polymer) is 0.1 or more and 1.0 or less.

8. The composition according to claim 1, wherein the electron donating compound is a polymer having a repeating unit represented by the following formula (1): (In formula (1), R １ and R ２ are the same or different and each is a hydrogen atom or an alkyl group.

9. The composition according to claim 1, wherein the electron accepting compound comprises at least one selected from the group consisting of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil), 7,7,8,8-tetracyanoquinodimethane (TCNQ), o-benzoquinone, m-benzoquinone, and p-benzoquinone.

10. The composition of any one of claims 1 to 9, further comprising an alkali metal-containing compound.

11. The composition of claim 10, wherein the alkali metal-containing compound comprises an alkali metal salt.

12. The composition of claim 10, wherein the alkali metal-containing compound comprises a lithium-containing compound.

13. A dry form of the composition according to any one of claims 1 to 9.

14. A dried product according to claim 13, wherein the solution obtained by dissolving the dried product in a non-aqueous solvent having a relative dielectric constant of more than 2.0 and less than 40 has a Gardner color number of 13 or more as measured in accordance with JIS K 0071-2.

15. A composition comprising the dried body of claim 13 and an alkali metal-containing compound.

16. A method for producing a composition according to any one of claims 1 to 9, comprising a step of mixing a first solution, which is a solution obtained by dissolving the electron-donating compound in a first solvent, with a second solution, which is a solution obtained by dissolving the electron-accepting compound in a second solvent, wherein the first solvent and the second solvent may be the same or different and are non-aqueous solvents having a relative dielectric constant greater than 2.0 and less than 40.

17. A method for producing a dried body according to claim 13, comprising the steps of: mixing a first solution, which is a solution in which the electron donor compound is dissolved in a first solvent, with a second solution, which is a solution in which the electron accepting compound is dissolved in a second solvent; and removing the non-aqueous solvent from the mixture of the first solution and the second solution, wherein the first solvent and the second solvent are the same or different and are non-aqueous solvents having a relative dielectric constant greater than 2.0 and less than 40.

18. A solid electrolyte formed using the composition of claim 10.

19. A solid electrolyte formed using the composition of claim 15.

20. An electricity storage device comprising the solid electrolyte according to claim 18.

21. An electricity storage device comprising the solid electrolyte according to claim 19.