Solid composition and method for manufacturing solid composition

Abstract

To provide a new solid composition that has ionic conductivity, excellent film-forming properties, and is easily usable as a solid electrolyte, and a method for manufacturing the same.SOLUTION: A solid composition according to the present disclosure includes at least one metal cation selected from the group consisting of alkali metal ions and alkaline earth metal ions, a cyclic imide anion represented by the following formula (A), and a polymer having at least one functional group selected from the group consisting of a cyano group (-CN), an oxa group (-O-), and a fluoro group (-F).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a solid composition and a method for making the solid composition. [Background technology]

[0002] In recent years, the performance of energy storage devices such as small, lightweight, and high-power lithium-ion secondary batteries has been further improved, and studies are underway to replace liquid electrolytes (electrolyte solutions) with solid electrolytes (solid electrolytes) in order to improve safety and achieve further improvements in performance and weight reduction. Materials such as ceramics, glass, polymers, and molecular crystals, which are crystalline organic materials, are considered promising types of solid electrolytes.

[0003] As solid electrolytes containing molecular crystals, ion-conducting electrolytes containing anions with cyclic structures such as LiN(SOCF)CF and LiN(SOCF) have been reported to have characteristics such as high ionic conductivity at room temperature and low temperature conditions, high flexibility, and ease of ensuring adhesion to electrodes (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-214510 Summary of the Invention [Problem to be solved by the invention]

[0005] As solid electrolyte technology continues to advance, there is a demand for improved film formability while maintaining ionic conductivity compared to the above-mentioned conventional technology.

[0006] An object of one aspect of the present disclosure is to provide a new solid composition that has ionic conductivity, excellent film-forming properties, and is easily usable as a solid electrolyte, and a method for producing the same. [Means for solving the problem]

[0007] As a result of extensive research aimed at solving the above problems, the present inventors have found that a solid composition containing a cation such as an alkali metal ion, a specific cyclic imide anion, and a specific polymer can be used as a material that has ionic conductivity, excellent film-forming properties, and is easily usable as a solid electrolyte, and have completed the present invention.

[0008] One aspect of the present invention is as follows. (1) A solid composition comprising at least one metal cation selected from the group consisting of alkali metal ions and alkaline earth metal ions, a cyclic imide anion represented by the following formula (A), and a polymer having at least one functional group selected from the group consisting of a cyano group (-CN), an oxa group (-O-), and a fluoro group (-F):

[0009] [ka]

[0010] (In formula (A), each L independently represents a divalent group represented by formula (L1), formula (L2), or formula (L3). In formula (A), R 1 represents a divalent carbon atom-containing fluorocarbon group which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2), or a divalent carbon atom-containing hydrocarbon group which may contain at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2). In formula (L3), R 2 represents a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), or an alkoxy group having 1 to 12 carbon atoms. Two R 2 When they have the same group, they may be the same or different groups. (2) The solid composition according to (1), wherein the cyclic imide anion is at least one selected from the group consisting of cyclic imide anions represented by the following formulae (A-1) to (A-4):

[0011] [ka]

[0012] (In formulas (A-1) to (A-4), R 1 represents a divalent carbon atom-containing fluorocarbon group which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2), or a divalent carbon atom-containing hydrocarbon group which may contain at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2). In formulas (A-3) and (A-4), R 2 represents a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), or an alkoxy group having 1 to 12 carbon atoms. 2 may be the same group or different groups.) (3) The solid composition according to (1) or (2), further comprising at least one nitrogen-containing cation selected from the group consisting of a cation represented by the following formula (B-1), a cation represented by the following formula (B-2), and a cation represented by the following formula (B-3):

[0013] [ka]

[0014] (In formulas (B-1) to (B-3), R 3 R each independently represents a hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2). 4R represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and an aza group (-N<, -N=, -NH-). 5 represents a trivalent hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and an aza group (-N<, -N=, -NH-). (4) The solid composition according to any one of (1) to (3), wherein the content of the polymer is 0.1 to 75.0% by mass relative to the total amount of the solid composition (when the total amount of the solid composition is taken as 100% by mass). (5) The solid composition according to any one of (1) to (4), which is used as a cation-conducting electrolyte. (6) A method for producing a solid composition, comprising: a salt preparation step of preparing a salt containing at least one metal cation selected from the group consisting of alkali metal ions and alkaline earth metal ions and a cyclic imide anion represented by the following formula (A); a mixing step of mixing the salt prepared in the salt preparation step with a polymer having at least one functional group selected from the group consisting of a cyano group (-CN), an oxa group (-O-), and a fluoro group (-F) in a solvent to obtain a mixed solution; and a solvent removal step of removing the solvent from the mixed solution obtained in the mixing step to obtain a solid composition.

[0015] [ka]

[0016] (In formula (A), each L independently represents a divalent group represented by formula (L1), formula (L2), or formula (L3). In formula (A), R 1represents a divalent carbon atom-containing fluorocarbon group which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2), or a divalent carbon atom-containing hydrocarbon group which may contain at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2). In formula (L3), R 2 represents a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), or an alkoxy group having 1 to 12 carbon atoms. Two R 2 When they have the same group, they may be the same or different groups. [Effects of the Invention]

[0017] According to one aspect of the present disclosure, there is provided a new solid composition that has ionic conductivity, excellent film-forming properties, and is easily usable as a solid electrolyte, and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0018] In explaining the present invention, specific examples will be given, but the present invention is not limited to the following content and can be implemented with appropriate modifications without departing from the spirit of the present invention.

[0019] In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0020] In the present disclosure, in the numerical ranges described in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples.

[0021] In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0022] In the present disclosure, combinations of preferred aspects are more preferred aspects.

[0023] In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

[0024] <Solid composition> A solid composition according to one embodiment of the present invention (hereinafter sometimes referred to as "the solid composition") comprises at least one metal cation (hereinafter sometimes referred to as "metal cation") selected from the group consisting of alkali metal ions and alkaline earth metal ions, a cyclic imide anion (hereinafter sometimes referred to as "cyclic imide anion") represented by the following formula (A), and a polymer (hereinafter sometimes referred to as "polymer") having at least one functional group selected from the group consisting of a cyano group (-CN), an oxa group (-O-), and a fluoro group (-F).

[0025] [ka]

[0026] (In formula (A), each L independently represents a divalent group represented by formula (L1), formula (L2), or formula (L3). In formula (A), R 1represents a divalent carbon atom-containing fluorocarbon group which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2), or a divalent carbon atom-containing hydrocarbon group which may contain at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2). In formula (L3), R 2 each independently represents a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), or an alkoxy group having 1 to 12 carbon atoms. 2 When they have the same group, they may be the same or different groups.

[0027] The present inventors have conducted extensive research in search of a new solid composition having ionic conductivity, and as a result have found that a solid composition containing the above-mentioned metal cation, cyclic imide anion, and polymer has ionic conductivity, is excellent in film-forming properties, and is a material that can be easily used as a solid electrolyte.

[0028] The solid composition means a composition that is "solid" at 25°C, and does not necessarily have to be solid at other temperatures.

[0029] Furthermore, for example, when determining whether a compound falls within the present solid composition, it is not necessary to confirm whether the metal cation, the cyclic imide anion, or the cation represented by formula (B-1) described below are ionized within the compound. This is because it is clear that alkali metals, alkaline earth metals, cyclic imides represented by formula (A), etc. tend to form strong ionic bonds, and the metal cations in the present solid composition represent this. In other words, if the present solid composition contains an alkali metal, alkaline earth metal, cyclic imide represented by formula (A), etc., it falls within the present solid composition.

[0030] The "metal cation," "cyclic imide anion," "polymer," and the like will be explained in detail below.

[0031] (metal cation) The metal cation is at least one selected from the group consisting of alkali metal ions and alkaline earth metal ions, but lithium ions (Li + ), sodium ions (Na + ), potassium ions (K + ), magnesium ions (Mg 2+ ), calcium ions (Ca 2+ ), and lithium ion (Li + ) is particularly preferred. The solid composition may contain two or more types of metal cations.

[0032] The total content of metal cations in the present solid composition is typically 0.5 to 12.0% by mass relative to the total amount of the solid composition (when the total amount of the solid composition is taken as 100% by mass), with the lower limit preferably being 1.0% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2.0% by mass or more, and the upper limit preferably being 10.0% by mass or less, more preferably 9.0% by mass or less, even more preferably 8.0% by mass or less, and particularly preferably 7.0% by mass or less. When the total content of metal cations is within the above range, ionic conductivity is easily ensured.

[0033] (cyclic imide anion) The cyclic imide anion is a compound represented by the following formula (A): The solid composition may contain two or more types of cyclic imide anions.

[0034] [ka]

[0035] In formula (A), R 1represents a divalent carbon atom-containing fluorocarbon group which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2), or a divalent carbon atom-containing hydrocarbon group which may contain at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2).

[0036] Here, in the above formula (A), the "divalent fluorocarbon group" means a group having two bonding positions and in which all hydrogen atoms of a hydrocarbon group have been substituted with fluorine atoms, and is not limited to a fluorocarbon group having a linear structure, but may also be a fluorocarbon group having at least one structure selected from the group consisting of a branched structure, a cyclic structure, and a carbon-carbon unsaturated bond structure (a carbon-carbon double bond structure and a carbon-carbon triple bond structure). In the above formula (A), the "divalent hydrocarbon group" is not limited to an aliphatic hydrocarbon group having a straight-chain structure, but may also be a hydrocarbon group having at least one structure selected from the group consisting of a branched structure, a cyclic structure, and a carbon-carbon unsaturated bond structure (a carbon-carbon double bond structure and a carbon-carbon triple bond structure). Furthermore, the number of the above structures is not particularly limited, and acyclic aliphatic hydrocarbon groups, monocyclic aliphatic hydrocarbon groups, polycyclic aliphatic hydrocarbon groups, monocyclic aromatic hydrocarbon groups, and polycyclic aromatic hydrocarbon groups are all included in the "hydrocarbon group," and alkylene groups, alkenylene groups, alkynylene groups, arylene groups, and the like are all included in the above "divalent hydrocarbon group."

[0037] In the above formula (A), the phrase "a fluorocarbon group which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2)" means that some of the carbon atoms of the fluorocarbon group may be substituted with at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2), excluding groups in which two or more oxa groups (-O-), two or more carbonyl groups (>C=O), and two or more sulfonyl groups (>S(=O)2) are linked in tandem.

[0038] In the above formula (A), the phrase "a hydrocarbon group optionally containing at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2)" means that some of the hydrogen atoms in the hydrocarbon group may be substituted with at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), and a bromo group (-Br), and some of the carbon atoms in the hydrocarbon group may be substituted with at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2). However, this does not include groups in which two or more oxa groups (-O-), two or more carbonyl groups (>C=O), and two or more sulfonyl groups (>S(=O)2) are linked in tandem.

[0039] In the above formula (A), R 1may be a divalent fluorocarbon group in which the carbon atoms are not substituted with other functional groups, or may be a divalent fluorocarbon group in which one or more carbon atoms are substituted with at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2), or may be a divalent hydrocarbon group in which the carbon atoms and hydrogen atoms are not substituted with other functional groups, or may be a divalent hydrocarbon group in which one or more hydrogen atoms are substituted with at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), and a bromo group (-Br), It may be a divalent hydrocarbon group in which one or more carbon atoms are substituted with at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2), or it may be a divalent hydrocarbon group in which one or more hydrogen atoms are substituted with at least one functional group selected from the group consisting of a fluoro group (-F), a chloro group (-Cl), and a bromo group (-Br), and in which one or more carbon atoms are substituted with at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2).

[0040] In formula (A), L each independently represents a divalent group represented by formula (L1), formula (L2), or formula (L3). The "divalent group represented by formula (L1), formula (L2), or formula (L3)" in L means a group having two bonding positions, and the wavy lines in formulas (L1) to (L3) indicate that the ends of the wavy lines connect N and R of the cyclic imide anion represented by formula (A). 1 This means that they are bonded to each other.

[0041] In formula (L3), R 2 represents a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), or an alkoxy group having 1 to 12 carbon atoms. Two R 2 When they have the same structure, they may be the same or different groups.

[0042] In formula (A), at least one of the two Ls is preferably a divalent group represented by formula (L1).

[0043] The cyclic imide anion is preferably at least one selected from the group consisting of cyclic imide anions represented by the following formulas (A-1) to (A-4): 1 and R 2 are R in formula (A), respectively. 1 and R 2 is the same as

[0044] [ka]

[0045] The cyclic imide anion represented by formula (A-1) is a cyclic imide anion in which two Ls in formula (A) are each a divalent group represented by formula (L1). The cyclic imide anion represented by formula (A-2) is a cyclic imide anion in which one of the two Ls in formula (A) is a divalent group represented by formula (L1), and the other L is a divalent group represented by formula (L2). The cyclic imide anion represented by formula (A-3) is a cyclic imide anion in which one of the two Ls in formula (A) is a divalent group represented by formula (L1), and the other L is a divalent group represented by formula (L3). The cyclic imide anion represented by formula (A-4) is a cyclic imide anion in which two Ls in formula (A) are each a divalent group represented by formula (L3).

[0046] In the above formula (A) and formulas (A-1) to (A-4), R 1 When is a fluorocarbon group having 2 to 8 carbon atoms, the number of carbon atoms is preferably 7 or less, more preferably 6 or less, even more preferably 4 or less, and particularly preferably 3 or less. R 1 When is a fluorocarbon group having 2 to 8 carbon atoms, the functional group that may be contained is preferably an oxa group (—O—).

[0047] R 1 When is a hydrocarbon group having 2 to 8 carbon atoms, the number of carbon atoms is preferably 7 or less, more preferably 6 or less, even more preferably 4 or less, and particularly preferably 3 or less. R 1 When is a hydrocarbon group having 2 to 8 carbon atoms, the functional group that may be contained is preferably a fluoro group.

[0048] R 1 Examples of the alkyl group include a tetrafluoroethylene group (-CF2CF2-), a hexafluoropropylene group (-CF2CF2CF2-), a tetrafluoroethyleneoxy group (-CF2CF2O-), an ethylene group (-CH2CH2-), a propylene group (-CH2CH2CH2-), and an ethyleneoxy group (-CH2CH2O-). R 1 As the alkyl group, a tetrafluoroethylene group (-CF2CF2-), a hexafluoropropylene group (-CF2CF2CF2-), or a tetrafluoroethyleneoxy group (-CF2CF2O-) is preferred, and a hexafluoropropylene group (-CF2CF2CF2-) is more preferred.

[0049] In the above formula (A) and formulas (A-1) to (A-4), R 2 When is an alkoxy group, the number of carbon atoms is preferably 8 or less, more preferably 6 or less, even more preferably 4 or less, and particularly preferably 3 or less.

[0050] R 2 Examples include fluoro (-F), chloro (-Cl), bromo (-Br), methoxy (-OCH3), ethoxy (-OC2H5), and n-propoxy (-O n C3H7), i-propoxy group (-O i C3H7), n-butoxy group (-O n C4H9), t-butoxy group (-O t C4H9), phenoxy group (-OC6H5), etc. R 2 As the group, a fluoro group (-F) is preferred.

[0051] Examples of the cyclic imide anion in the present solid composition include a cyclic imide anion represented by the following formula (A-1-1), a cyclic imide anion represented by the following formula (A-1-2), a cyclic imide anion represented by the following formula (A-2-1), a cyclic imide anion represented by the following formula (A-3-1), and a cyclic imide anion represented by the following formula (A-4-1).

[0052] [ka]

[0053] The total content of cyclic imide anions in the present solid composition is typically 25.0 to 99.9% by mass relative to the total amount of the solid composition (when the total amount of the solid composition is taken as 100% by mass), with the lower limit preferably being 50.0% by mass or more, more preferably 75% by mass or more, and even more preferably 95% by mass or more, and the upper limit preferably being 99.9% by mass or less, more preferably 97% by mass or less, even more preferably 95.5% by mass or less, and particularly preferably 95% by mass or less. When the total content of cyclic imide anions is within the above range, ionic conductivity is easily ensured.

[0054] The molar ratio of cyclic imide anion to metal cation in the solid composition (molar amount of cyclic imide anion / molar amount of metal cation) is typically 1.00 to 0.01, with the lower limit preferably being 0.03 or more, more preferably 0.06 or more, and even more preferably 0.09 or more, and the upper limit preferably being 0.86 or less, more preferably 0.80 or less, and even more preferably 0.67 or less. When the molar ratio of cyclic imide anion is within the above range, ionic conductivity is easily ensured.

[0055] (polymer) The polymer has at least one functional group selected from the group consisting of a cyano group (-CN), an oxa group (-O-), and a fluoro group (-F). The phrase "having at least one functional group selected from the group consisting of a cyano group (-CN), an oxa group (-O-), and a fluoro group (-F)" refers to a polymer in which some hydrogen atoms in the hydrocarbon groups of the main chain, side chain, or main chain and side chain are substituted with a cyano group (-CN, also called a nitrile group), a fluoro group (-F), or the like, or some carbon atoms in the hydrocarbon groups of the main chain, side chain, or main chain and side chain are substituted with an oxa group (-O-, also called an ether group). The solid composition may contain two or more types of polymers.

[0056] Examples of polymers having a cyano group (-CN) include homopolymers or copolymers containing acrylonitrile as a monomer, and examples of monomers copolymerizable with acrylonitrile include styrene, butadiene, and (meth)acrylic acid esters such as butyl acrylate.

[0057] Examples of polymers having a cyano group (-CN) include polyacrylonitrile (PAN), poly(styrene-co-acrylonitrile) (SAN), poly(acrylonitrile-co-butadiene-co-styrene) (ABS), poly(acrylonitrile-co-styrene-co-acrylic acid ester) (ASA), and acrylonitrile butadiene rubber (NBR), with PAN being preferred.

[0058] Examples of polymers having an oxa group (-O-) include polymers in which some carbon atoms in the hydrocarbon group of the main chain are substituted with an oxa group (-O-), such as polyalkylene oxide (polyethylene oxide (PEO), polypropylene oxide (PPO), polyacetal (polyoxymethylene, POM)), polyphenylene oxide (PPO), and polyether ketone (PEEK), and homopolymers or copolymers containing an alkoxypolyalkylene oxide acrylate as a monomer, with PEO being preferred.

[0059] Examples of polymers having a fluoro group (-F) include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), and ethylenetetrafluoroethylene copolymer (ETFE), with PVDF being preferred.

[0060] The total polymer content in the present solid composition is typically 0.1 to 75.0% by mass relative to the total amount of the solid composition (when the total amount of the solid composition is taken as 100% by mass), with the lower limit preferably being 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 3.0% by mass or more, and the upper limit preferably being 50.0% by mass or less, more preferably 25.0% by mass or less, even more preferably 15.0% by mass or less, and particularly preferably 5.0% by mass or less. When the total polymer content is within the above range, ionic conductivity is easily ensured.

[0061] The ratio of the amount of polymer to the amount of metal cation in the solid composition (amount of polymer [mol] / amount of metal cation [mol]) is typically 5.0 × 10 -8 ~2.0×10 -2 The lower limit is preferably 6.0 × 10 -3 More preferably, 2.0 × 10 -3 More preferably, 3.0 × 10 -4 The upper limit is preferably 2.0 × 10 -7 or less, preferably 4.0 × 10 -7 or less, more preferably 1.0 × 10 -6 Below 2.0 × 10, particularly preferably -6 When the substance amount ratio of the polymer is within the above range, ionic conductivity can be easily ensured.

[0062] The solid composition may contain other components as long as it contains the metal cation, the cyclic imide anion, and the polymer. Examples of the other components include at least one nitrogen-containing cation (hereinafter sometimes abbreviated as "nitrogen-containing cation") selected from the group consisting of a cation represented by the following formula (B-1), a cation represented by the following formula (B-2), and a cation represented by the following formula (B-3). The inclusion of a nitrogen-containing cation facilitates the production of the solid composition and makes it easier to use as a solid electrolyte.

[0063] [ka]

[0064] (In formulas (B-1) to (B-3), R 3 R each independently represents a hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2). 4 R represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and an aza group (-N<, -N=, -NH-). 5 represents a trivalent hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and an aza group (-N<, -N=, -NH-).

[0065] In formula (B-1), R 3 The hydrocarbon group as R in the above formula (A) 1 It has the same meaning as the "hydrocarbon group" in the "divalent hydrocarbon group" as above.

[0066] R 3 The number of carbon atoms in the hydrocarbon group is preferably 7 or less, more preferably 6 or less, even more preferably 4 or less, and particularly preferably 3 or less.

[0067] R 3 The hydrocarbon groups are methyl (-CH3), ethyl (-CH2CH3), vinyl (-CH=CH2), n-propyl (-CH2CH2CH3), i-propyl (-CH(CH3)2), n-butyl (-CH2CH2CH2CH3), t-butyl (-C(CH3)2), cyclohexyl (-CH6H 11 ), a phenyl group (-C6H5), etc. Among these, a methyl group (-CH3) and an ethyl group (-CH2CH3) are preferred.

[0068] In formula (B-2), R 4 The hydrocarbon group as R in the above formula (A) 1 It has the same meaning as the "hydrocarbon group" in the "divalent hydrocarbon group" as above.

[0069] R 4 The number of carbon atoms in the hydrocarbon group is preferably 7 or less, more preferably 6 or less, even more preferably 4 or less, and particularly preferably 3 or less.

[0070] R 4 Examples of the hydrocarbon group include an ethylene group (-CH2CH2-), a vinylene group (-CH=CH-), an n-propylene group (-CH2CH2CH2-), an n-butylene group (-CH2CH2CH2CH2-), an n-heptylene group (-CH2CH2CH2CH2CH2-), etc. Among these, an n-butylene group (-CH2CH2CH2CH2-) and an n-heptylene group (-CH2CH2CH2CH2CH2-) are preferred.

[0071] In formula (B-3), R 5 The hydrocarbon group as R in the above formula (A) 1 It has the same meaning as the "hydrocarbon group" in the "divalent hydrocarbon group" as above.

[0072] R 5 The number of carbon atoms in the hydrocarbon group is preferably 7 or less, more preferably 6 or less, even more preferably 4 or less, and particularly preferably 3 or less.

[0073] Examples of nitrogen-containing cations include those represented by the following formulae (triethylmethylammonium cation, tri-t-butylmethylammonium cation, triphenylmethylammonium cation, tetramethylammonium cation, tetra-t-butylammonium cation, tetraphenylammonium cation, N-methylimidazolium cation, N,N-dimethylpyrrolidinium cation, N-methylpyridinium cation, and N,N-dimethylpiperidinium cation). In the following formulae, Me represents a methyl group (-CH3), Et represents an ethyl group (-CH2CH3), t Bu represents a t-butyl group (-C(CH3)2), and Ph represents a phenyl group (-C6H5).

[0074] [ka]

[0075] The total content of nitrogen-containing cations in the present solid composition is typically 0.0 to 25.0% by mass relative to the total amount of the solid composition (when the total amount of the solid composition is taken as 100% by mass), with the lower limit preferably being 3.0% by mass or more, more preferably 6.0% by mass or more, and even more preferably 12.2% by mass or more, and the upper limit preferably being 24.5% by mass or less, more preferably 24.0% by mass or less, even more preferably 23.5% by mass or less, and particularly preferably 23.0% by mass or less. When the total content of nitrogen-containing cations is within the above range, the solid composition is easy to produce and can be easily used as a solid electrolyte.

[0076] The ratio of the amount of substance of nitrogen-containing cations to metal cations in the present solid composition (amount of substance [mol] of nitrogen-containing cations / amount of substance [mol] of metal cations) is usually 0.0 to 100.0, with the lower limit preferably being 0.3 or more, more preferably 0.5 or more, and even more preferably 1.0 or more, and the upper limit preferably being 50.0 or less, more preferably 25.0 or less, even more preferably 10.0 or less, and particularly preferably 2.0 or less. When the ratio of the amount of substance of nitrogen-containing cations is within the above range, the solid composition is easy to produce and can be easily used as a solid electrolyte.

[0077] (Form of Existence in the Solid Composition) The solid composition is not particularly limited in terms of its form as long as it contains the metal cation, the cyclic imide anion, and the polymer. However, it is preferable that the solid composition contains a crystal (molecular crystal) formed by the metal cation and the cyclic imide anion. The presence of the crystal formed by the metal cation and the cyclic imide anion makes it easier to ensure ionic conductivity. The presence of the crystal formed by the metal cation and the cyclic imide anion in the solid composition can be confirmed by subjecting the solid composition to an X-ray diffraction (XRD) device.

[0078] When the present solid composition contains a nitrogen-containing cation, it preferably contains a crystal formed between the nitrogen-containing cation and the cyclic imide anion. The inclusion of a crystal formed between the nitrogen-containing cation and the cyclic imide anion facilitates the production of the solid composition and facilitates its use as a solid electrolyte. The presence of the crystal formed between the nitrogen-containing cation and the cyclic imide anion in the present solid composition can be confirmed by subjecting the solid composition to an X-ray diffraction (XRD) device.

[0079] (Ionic Conductivity of the Solid Composition) The ionic conductivity σ of the solid composition is typically 1.0 × 10 -5 mS / cm or more and 1.0 mS / cm or less, and the lower limit is preferably 1.0 × 10 -4 mS / cm or more, preferably 1.0 × 10 -3 mS / cm or more, more preferably 1.0 × 10 -2 mS / cm or more, particularly preferably 1.0 × 10 -1 mS / cm or more.

[0080] <Method of producing solid composition> A method for producing a solid composition according to one embodiment of the present invention (hereinafter sometimes abbreviated as "the method for producing the solid composition") includes a salt preparation step of preparing a salt containing at least one metal cation (hereinafter sometimes abbreviated as "metal cation") selected from the group consisting of alkali metal ions and alkaline earth metal ions and a cyclic imide anion represented by formula (A) (hereinafter sometimes abbreviated as "cyclic imide anion"), a mixing step of mixing the salt prepared in the salt preparation step with a polymer (hereinafter sometimes abbreviated as "polymer") having at least one functional group selected from the group consisting of a cyano group (-CN), an oxa group (-O-), and a fluoro group (-F) in a solvent to obtain a mixed solution, and a solvent removal step of removing the solvent from the mixed solution obtained in the mixing step to obtain a solid composition.

[0081] The metal cation, cyclic imide anion, and polymer in the method for producing the present solid composition are the same as the metal cation, cyclic imide anion, and polymer in the above <Solid Composition>.

[0082] The "salt preparation step," "mixing step," "solvent removal step," etc. will be described in detail below.

[0083] (Salt preparation process) The salt in the salt preparation step preferably further contains at least one nitrogen-containing cation (hereinafter sometimes abbreviated as "nitrogen-containing cation") selected from the group consisting of cations represented by the following formula (B-1), cations represented by the following formula (B-2), and cations represented by the following formula (B-3): The inclusion of a nitrogen-containing cation improves the flexibility of the solid composition, making it possible to improve the formability of the solid electrolyte and reduce the influence of grain boundaries on ion conduction inhibition.

[0084] [ka] (In formulas (B-1) to (B-3), R 3R each independently represents a hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and a sulfonyl group (>S(=O)2). 4 R represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and an aza group (-N<, -N=, -NH-). 5 represents a trivalent hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (-O-), a carbonyl group (>C=O), and an aza group (-N<, -N=, -NH-).

[0085] The nitrogen-containing cation in the method for producing the present solid composition is the same as the nitrogen-containing cation in the above <Solid Composition>.

[0086] The salt preparation step may include a salt mixing operation of mixing a salt containing a metal cation and a cyclic imide anion with a salt containing a nitrogen-containing cation and a cyclic imide anion, a heating operation of heating the mixed salts, and a drying operation of drying the mixed salts.

[0087] The heating temperature for the heating operation in the salt preparation step is typically 25 to 300°C, with the lower limit preferably being 50°C or higher, more preferably 100°C or higher, and even more preferably 150°C or higher, and the upper limit preferably being 275°C or lower, more preferably 250°C or lower, even more preferably 225°C or lower, and particularly preferably 200°C or lower.

[0088] The heating time for the heating operation in the salt preparation step is usually 1 to 168 hours, with the lower limit preferably being 12 hours or more, more preferably 24 hours or more, and the upper limit preferably being 96 hours or less, more preferably 72 hours or less, even more preferably 48 hours or less, and particularly preferably 24 hours or less.

[0089] (Mixing process) The mixing step is a step of mixing the salt prepared in the salt preparation step with a polymer in a solvent to obtain a mixed solution, and examples of the solvent include N-methylpyrrolidone, tetrahydrofuran, acetone, isopropyl alcohol, ethanol, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, N,N-dimethylacetamide, cyclohexanone, methyl ethyl ketone, etc. The mixing step may include a stirring operation of stirring the solvent containing the salt prepared in the salt preparation step and the polymer.

[0090] The stirring time for the stirring operation in the mixing step is usually 10 minutes to 168 hours, with the lower limit preferably being 1 hour or more, more preferably 6 hours or more, and even more preferably 12 hours or more, and the upper limit preferably being 96 hours or less, more preferably 72 hours or less, even more preferably 48 hours or less, and particularly preferably 24 hours or less.

[0091] (Solvent removal process) The solvent removal step is a step of removing the solvent from the mixed solution obtained in the mixing step to obtain a solid composition. The solvent removal step may include a heating operation of heating the mixed solution obtained in the mixing step.

[0092] The heating temperature for the heating operation in the solvent removal step is usually 20 to 200°C, with the lower limit being preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher, and the upper limit being preferably 175°C or lower, more preferably 150°C or lower, even more preferably 125°C or lower, and particularly preferably 100°C or lower.

[0093] The heating time for the heating operation in the solvent removal step is usually 5 minutes to 48 hours, with the lower limit preferably being 1 hour or more, more preferably 2 hours or more, and even more preferably 3 hours or more, and the upper limit preferably being 36 hours or less, more preferably 24 hours or less, even more preferably 12 hours or less, and particularly preferably 6 hours or less. [Example]

[0094] Examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples.

[0095] Example 1 (Preparation 1 of a solid composition containing polyacrylonitrile (PAN)) 2.7849 g of triethylmethylammonium chloride was dissolved in 8 mL of ion-exchanged water. + ·CPFSA - 5.4959 g of the lithium salt represented by the formula (2) was dissolved in 8 mL of ion-exchanged water, and the entire amount was added dropwise to an aqueous triethylmethylammonium chloride solution. The mixed solution was stirred at room temperature for 3 hours, and then filtered through a membrane filter (Millipore Corporation, product name "Omnipore", model number "JAWP04700"). The solid remaining on the membrane filter was collected in a Schlenk flask and dried in vacuum at approximately 100°C for 48 hours to obtain a sample.

[0096] [ka]

[0097] Next, the obtained sample was subjected to the following formula (N1222 + ·CPFSA - ) was added in an amount of 0.1 molar equivalent, and the mixture was heated and stirred at 270° C. The obtained salt was dried in vacuum at 150° C.

[0098] [ka]

[0099] Next, the obtained salt and PAN were each dissolved in N-methylpyrrolidone (NMP), and then the NMP solutions were weighed to a salt:polymer ratio of 95% by mass:5% by mass, and mixed for 2 hours using a magnetic stirrer. Finally, the resulting mixed solution was dried at 90°C under normal pressure for 5 hours to obtain Solid Composition 1.

[0100] Example 2 (Preparation 2 of a solid composition containing PAN) Solid composition 2 was obtained in the same manner as in Example 1, except that the salt:polymer ratio described in Example 1 was changed to salt:polymer = 85% by mass: 15% by mass.

[0101] Example 3 (Preparation 3 of a solid composition containing PAN) Solid composition 3 was obtained in the same manner as in Example 1, except that the salt:polymer ratio described in Example 1 was changed to salt:polymer = 75% by mass: 25% by mass.

[0102] Example 4 (Preparation of a solid composition containing polyethylene oxide (PEO)) Solid composition 4 was obtained in the same manner as in Example 1, except that the PAN used in Example 1 was changed to PEO.

[0103] Example 5 (Preparation of a solid composition containing polyvinylidene fluoride (PVDF)) Solid composition 5 was obtained in the same manner as in Example 1, except that the PAN used in Example 1 was changed to PVDF.

[0104] Comparative Example 1 (Preparation of Polymer-Free Solid Composition) Solid Composition 6 was obtained in the same manner as in Example 1, except that PAN was not mixed with the salt described in Example 1.

[0105] <Measurement of ionic conductivity> For each of the solid compositions 1 to 6, a disk-shaped pellet having a thickness of 1 cm was prepared using a hydraulic press. Next, both electrodes of the prepared pellet were sandwiched between gold plates and then sealed in a sealed cell, and the ionic conductivity was calculated by the AC impedance method. The AC impedance measurement conditions were as follows: DC voltage [V]: 0.1V Frequency [Hz]: 1MHz~1Hz ·Amplitude [mV]: 100mV ·Measurement temperature [℃]: 30℃ Measurement equipment: BioLogic VMP-potentiostat / galvanostat

[0106] The ionic conductivity was calculated by curve fitting the obtained impedance spectrum to calculate the resistance R (Ω) related to ionic conduction, and then calculating the ionic conductivity σ (mS / cm) based on the following formula. The results are shown in Table 1.

[0107] σ=1 / (R×A) 1: Pellet thickness [cm], A: Pellet area [cm 2 ]

[0108] <Winding test> Solid compositions 1 to 6 were each dissolved in N-methylpyrrolidone (NMP) to a concentration of 9% by mass, and then coated onto aluminum foil so that the resulting solid composition would be 80 μm thick after drying, and then wrapped around a metal rod with an inner diameter of 3 mm. Each solid composition was then visually inspected for the presence or absence of cracks or breaks. Those with no cracks or breaks were evaluated as "Good," and those with cracks or breaks were evaluated as "Poor." The results are shown in Table 1.

[0109] [Table 1]

[0110] The results in Table 1 reveal that polymer-containing solid compositions 1 to 5 (Examples 1 to 5) have improved film-forming properties while retaining ionic conductivity, compared to polymer-free solid composition 6 (Comparative Example 1). The addition of polymers to solid compositions containing polymers improves flexibility and density, which is thought to reduce resistance at particle-particle interfaces. In particular, PAN and PEO are thought to promote dissociation from cyclic imide anions by interacting with lithium cations via cyano groups (-CN) and oxa groups (-O-), thereby improving the ionic conductivity of lithium ions. [Industrial Applicability]

[0111] According to the present invention, it is possible to provide a new solid composition that has ionic conductivity, excellent film-forming properties, and is easily usable as a solid electrolyte, and a method for producing the same.

Claims

1. at least one metal cation selected from the group consisting of alkali metal ions and alkaline earth metal ions; A cyclic imide anion represented by the following formula (A): a polymer having at least one functional group selected from the group consisting of a cyano group (—CN), an oxa group (—O—), and a fluoro group (—F); A solid composition comprising: 【Chemical 1】 (In formula (A), each L independently represents a divalent group represented by formula (L1), formula (L2), or formula (L3). In formula (A), R １ represents an oxa group (—O—), a carbonyl group (>C═O), and a sulfonyl group (>S(═O) ２ a divalent fluorocarbon group having 2 to 8 carbon atoms, which may contain at least one functional group selected from the group consisting of a fluoro group (—F), a chloro group (—Cl), a bromo group (—Br), an oxa group (—O—), a carbonyl group (>C═O), and a sulfonyl group (>S(═O) ２ In formula (L3), R represents a divalent hydrocarbon group having 2 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of ２ represents a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), or an alkoxy group having 1 to 12 carbon atoms. ２ When they have the same group, they may be the same or different groups.)

2. 2. The solid composition according to claim 1, wherein the cyclic imide anion is at least one selected from the group consisting of cyclic imide anions represented by the following formulas (A-1) to (A-4): 【Chemistry 2】 (In formulas (A-1) to (A-4), R １ represents an oxa group (—O—), a carbonyl group (>C═O), and a sulfonyl group (>S(═O) ２ a divalent fluorocarbon group having 2 to 8 carbon atoms, which may contain at least one functional group selected from the group consisting of a fluoro group (—F), a chloro group (—Cl), a bromo group (—Br), an oxa group (—O—), a carbonyl group (>C═O), and a sulfonyl group (>S(═O) ２ In formula (A-3) and formula (A-4), R represents a divalent hydrocarbon group having 2 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of ２ represents a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), or an alkoxy group having 1 to 12 carbon atoms. ２ may be the same group or different groups.)

3. The solid composition according to claim 1, further comprising at least one nitrogen-containing cation selected from the group consisting of a cation represented by the following formula (B-1), a cation represented by the following formula (B-2), and a cation represented by the following formula (B-3): 【Chemistry 3】 (In formulas (B-1) to (B-3), R ３ are each independently an oxa group (—O—), a carbonyl group (>C═O), and a sulfonyl group (>S(═O) ２ R represents a hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of ４ represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (—O—), a carbonyl group (>C═O), and an aza group (—N<, —N═, —NH—). ５ represents a trivalent hydrocarbon group having 1 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of an oxa group (—O—), a carbonyl group (>C═O), and an aza group (—N<, —N═, —NH—).

4. 2. The solid composition according to claim 1, wherein the content of the polymer is 0.1 to 75.0% by mass relative to the total amount of the solid composition (when the total amount of the solid composition is taken as 100% by mass).

5. 10. The solid composition of claim 1 used as a cation-conducting electrolyte.

6. a salt preparation step of preparing a salt containing at least one metal cation selected from the group consisting of alkali metal ions and alkaline earth metal ions and a cyclic imide anion represented by the following formula (A); a mixing step of mixing the salt prepared in the salt preparation step with a polymer having at least one functional group selected from the group consisting of a cyano group (—CN), an oxa group (—O—), and a fluoro group (—F) in a solvent to obtain a mixed solution; and a solvent removal step of removing the solvent from the mixed solution obtained in the mixing step to obtain a solid composition; A method for producing a solid composition, comprising: 【Chemistry 4】 (In formula (A), each L independently represents a divalent group represented by formula (L1), formula (L2), or formula (L3). In formula (A), R １ represents an oxa group (—O—), a carbonyl group (>C═O), and a sulfonyl group (>S(═O) ２ a divalent fluorocarbon group having 2 to 8 carbon atoms, which may contain at least one functional group selected from the group consisting of a fluoro group (—F), a chloro group (—Cl), a bromo group (—Br), an oxa group (—O—), a carbonyl group (>C═O), and a sulfonyl group (>S(═O) ２ In formula (L3), R represents a divalent hydrocarbon group having 2 to 8 carbon atoms which may contain at least one functional group selected from the group consisting of ２ represents a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), or an alkoxy group having 1 to 12 carbon atoms. ２ When they have the same group, they may be the same or different groups.)

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