Lithium ion-conductive material and secondary battery

Abstract

A novel lithium ion-conductive material is disclosed. The lithium ion-conductive material according to the present disclosure comprises a perfluoropolyether represented by formula (1) and LiI dissolved in this perfluoropolyether. (1) E1-Rf1-RF-O-Rf2-E2 [In formula (1), Rf1 and Rf2 are each independently a C1-16 divalent alkylene group, which may be substituted by one or more fluorine atoms; E1 and E2 are each independently a monovalent group selected from the group consisting of a fluorine group, hydrogen group, hydroxyl group, aldehyde group, carboxylic acid group, C1-10 alkyl ester group, amide group possibly having one or more substituents, and amino group possibly having one or more substituents; and RF is a divalent fluoropolyether group.]

Description

Lithium ion conductive materials and secondary batteries

[0001] The present application discloses a lithium ion conducting material and a secondary battery.

[0002] Patent Document 1 discloses mixing a perfluoropolyether as a texturing agent into a solid polymer electrolyte. Patent Document 2 discloses a perfluoropolyether as an additive component of a non-aqueous electrolyte. Patent Document 3 discloses having a perfluoropolyether group-containing compound present on the surface of an electrode to improve the storage stability of the electrode.

[0003] JP-T-2018-513539 A JP-A-2018-200866 A JP-A-2018-147887 A

[0004] As disclosed in Patent Documents 1 to 3, perfluoropolyethers are used as various battery materials. However, since perfluoropolyether itself does not have lithium ion conductivity, when perfluoropolyether is used as a battery material, the resistance of the battery tends to increase. In this regard, a new technology that can impart lithium ion conductivity to perfluoropolyether is needed.

[0005] Furthermore, when considering applications to various uses such as batteries, lithium ion conductive materials are required to have low reactivity with lithium in addition to lithium ion conductivity.

[0006] The present application discloses the following embodiments as means for solving the above problems. <Embodiment 1> A lithium ion conductive material comprising a perfluoropolyether represented by the following formula (1), and LiI dissolved in the perfluoropolyether. １ -Rf １ -R Ｆ -O-Rf ２ -E ２ (1) [In formula (1), Rf １ and Rf ２ each independently represents a C1-16 divalent alkylene group optionally substituted by one or more fluorine atoms, １and E ２ are each independently a monovalent group selected from the group consisting of a fluorine group, a hydrogen group, a hydroxyl group, an aldehyde group, a carboxylic acid group, a C1-10 alkyl ester group, an amide group which may have one or more substituents, and an amino group which may have one or more substituents; R Ｆ is a divalent fluoropolyether group.] <Aspect 2> The R Ｆ is expressed by the formula (2): -(OC ６ F １２ ) ａ - (OC ５ F １０ ) ｂ - (OC ４ F ８ ) ｃ - (OC ３ R Ｆａ ６ ) ｄ - (OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2) [In formula (2), R Ｆａ are each independently a hydrogen atom, a fluorine atom, or a chlorine atom in each occurrence; a, b, c, d, e, and f are each independently an integer of 0 to 200; the sum of a, b, c, d, e, and f is 1 or more; the order of occurrence of each repeating unit enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula; provided that all R Ｆａ is a hydrogen atom or a chlorine atom, at least one of a, b, c, e, and f is 1 or more. Ｆａ The lithium ion conductive material of Aspect 2, wherein R is a fluorine atom. Ｆ each occurrence independently represents the following formula (2-1), (2-2), (2-3), (2-4) or (2-5): -(OC ３ F ６ ) ｄ - (OC ２ F ４ ) ｅ- (2-1) [In formula (2-1), d is an integer of 1 to 200, and e is 0 or 1.], -(OC ４ F ８ ) ｃ - (OC ３ F ６ ) ｄ - (OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2-2) [In formula (2-2), c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer of 1 to 200, the sum of c, d, e and f is an integer of 10 to 200, and the order of occurrence of each repeating unit enclosed in parentheses with the subscript c, d, e or f is arbitrary in the formula.], - (R ６ -R ７ ) ｇ - (2-3) [In formula (2-3), R ６ is OCF ２ or O.C. ２ F ４ and R ７ is O.C. ２ F ４ , O.C. ３ F ６ , O.C. ４ F ８ , O.C. ５ F １０ and O.C. ６ F １２ or a combination of two or three groups selected from these groups, and g is an integer of 2 to 100. ６ F １２ ) ａ - (OC ５ F １０ ) ｂ - (OC ４ F ８ ) ｃ - (OC ３ F ６ ) ｄ - (OC ２ F ４ ) ｅ -(OCF ２ ) ｆ- (2-4) [In formula (2-4), e represents an integer of 1 or more and 200 or less, a, b, c, d, and f each independently represent an integer of 0 or more and 200 or less, and the order of occurrence of each repeating unit enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula.] - (OC ６ F １２ ) ａ - (OC ５ F １０ ) ｂ - (OC ４ F ８ ) ｃ - (OC ３ F ６ ) ｄ - (OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2-5) [in formula (2-5), f is an integer of 1 or more and 200 or less, a, b, c, d, and e are each independently an integer of 0 or more and 200 or less, and the order of the repeating units enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula]. Ｆ is represented by the following formula (2-6): -(OCF ２ CF ２ CF ２ ) ａ -(OCF(CF ３ )CF ２ ) ｂ -(OCF ２ CF (CF ３ )) ｃ -(OCF ２ CF ２ ) ｄ -(OCF(CF ３ )) ｅ -(OCF ２ ) ｆ- (2-6) [in formula (2-6), a, b, c, d, e, and f each independently represent an integer of 0 to 200, the sum of a, b, c, d, e, and f is 1 or more, and the order of the repeating units enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula]. Ｆ is represented by the following formula (2-7): -(OCF ２ CF ２ ) ｄ -(OCF(CF ３ )) ｅ -(OCF ２ ) ｆ - (2-7) [in formula (2-7), d, e, and f each independently represent an integer of 0 to 200, the sum of d, e, and f is 1 or more, and the order of the repeating units enclosed in parentheses with d, e, or f is arbitrary in the formula]. １ -Rf １ and the above E ２ -Rf ２ are each independently -CF ３ , -CF ２ CF ３ , and -CF ２ CF ２ CF ３ The lithium ion conductive material of any one of Aspects 1 to 6, wherein the group is a group selected from the group consisting of: Aspect 8 A secondary battery having a positive electrode, an electrolyte layer, and a negative electrode, wherein at least one of the positive electrode, the electrolyte layer, and the negative electrode comprises the lithium ion conductive material of any one of Aspects 1 to 7.

[0007] According to the technology of the present disclosure, it is possible to impart lithium ion conductivity to perfluoropolyether. The lithium ion conductive material of the present disclosure has lithium ion conductivity but low reactivity with lithium.

[0008] 1 shows a schematic diagram of an example of the configuration of a secondary battery.

[0009] 1. Lithium ion conductive material Hereinafter, an embodiment of the technology of the present disclosure will be described, but the technology of the present disclosure is not limited to the following embodiment. The lithium ion conductive material of the present disclosure contains a perfluoropolyether represented by the following formula (1) and LiI dissolved in the perfluoropolyether.

[0010] 1.1 Perfluoropolyether (PFPE) Perfluoropolyether (PFPE) can be used as a texturing agent to change the mechanical properties of battery materials. According to the inventors' new findings, when solid battery materials (active materials, solid electrolytes, conductive materials, etc.) are mixed with PFPE, the lubricating effect of PFPE improves the fluidity of the battery material, which tends to increase the packing rate of the battery material when molded. Furthermore, since PFPE has many ether bonds, it is believed to have a high affinity for various battery materials and is likely to coexist appropriately with battery materials. Furthermore, because PFPE has insulating properties, for example, incorporating PFPE into a battery separator layer (electrolyte layer) can improve the voltage resistance of the separator layer.

[0011] The perfluoropolyether is represented by the following formula (1).

[0012] E １ -Rf １ -R Ｆ -O-Rf ２ -E ２ (1) [In formula (1), Rf １ and Rf ２ each independently represents a C1-16 divalent alkylene group optionally substituted by one or more fluorine atoms, １ and E ２ are each independently a monovalent group selected from the group consisting of a fluorine group, a hydrogen group, a hydroxyl group, an aldehyde group, a carboxylic acid group, a C1-10 alkyl ester group, an amide group which may have one or more substituents, and an amino group which may have one or more substituents; R Ｆ is a divalent fluoropolyether group.

[0013] In the above formula (1), Rf １and Rf ２ are each independently a C1-16 divalent alkylene group optionally substituted with one or more fluorine atoms.

[0014] In one aspect, the "C1-16 divalent alkylene group" in the above-mentioned C1-16 divalent alkylene group optionally substituted by one or more fluorine atoms may be straight-chain or branched-chain, and may preferably be a straight-chain or branched-chain C1-6 alkylalkylene group, particularly a C1-3 alkylene group, and more preferably a straight-chain C1-6 alkylene group, particularly a C1-3 alkylene group.

[0015] In one embodiment, the "C1-16 divalent alkylene" in the C1-16 divalent alkylene group optionally substituted by one or more fluorine atoms may be a straight chain or a branched chain, and is preferably a straight chain or branched chain C1-6 fluoroalkylene group, particularly a C1-3 fluoroalkylene group, and specifically, -CF ２ CH ２ - and -CF ２ CF ２ CH ２ -, and more preferably a linear C1-6 perfluoroalkylene group, particularly a C1-3 perfluoroalkylene group, specifically -CF ２ -, -CF ２ CF ２ - and -CF ２ CF ２ CF ２ - may be a group selected from the group consisting of

[0016] In the above formula (1), E １ and E ２ are each independently a monovalent group selected from the group consisting of a fluorine group, a hydrogen group, a hydroxyl group, an aldehyde group, a carboxylic acid group, a C1-10 alkyl ester group, an amide group which may have one or more substituents, and an amino group which may have one or more substituents.

[0017] The above-mentioned PFPE has low reactivity with lithium. In particular, when the PFPE has a non-polar group as a terminal group, the reactivity with lithium can be further suppressed. In this respect, the above-mentioned E １ and E ２ are each independently preferably a fluorine group. １ -Rf １ and E ２ -Rf ２ are each independently -CF ３ , -CF ２ CF ３ , and -CF ２ CF ２ CF ３ It may be a group selected from the group consisting of:

[0018] In the above formula (1), R Ｆ is independently at each occurrence a divalent fluoropolyether group.

[0019] R Ｆ is preferably represented by the formula (2): -(OC ６ F １２ ) ａ - (OC ５ F １０ ) ｂ - (OC ４ F ８ ) ｃ - (OC ３ R Ｆａ ６ ) ｄ - (OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2) [In formula (2): R Ｆａ are each independently a hydrogen atom, a fluorine atom, or a chlorine atom in each occurrence; a, b, c, d, e, and f are each independently an integer of 0 to 200; the sum of a, b, c, d, e, and f is 1 or more; the order of occurrence of each repeating unit enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula; provided that all R Ｆａis a hydrogen atom or a chlorine atom, then at least one of a, b, c, e and f is 1 or greater.]

[0020] R Ｆａ is preferably a hydrogen atom or a fluorine atom, and more preferably a fluorine atom.

[0021] a, b, c, d, e and f may preferably each independently be an integer of 0 to 100.

[0022] The sum of a, b, c, d, e, and f is preferably 5 or more, more preferably 10 or more, and may be, for example, 15 or more or 20 or more. The sum of a, b, c, d, e, and f is preferably 200 or less, more preferably 100 or less, and even more preferably 60 or less, and may be, for example, 50 or less or 30 or less.

[0023] These repeating units may be linear or branched. For example, -(OC ６ F １２ )- is -(OCF ２ CF ２ CF ２ CF ２ CF ２ CF ２ )-,-(OCF(CF ３ )CF ２ CF ２ CF ２ CF ２ ) -, -(OCF ２ CF (CF ３ )CF ２ CF ２ CF ２ ) -, -(OCF ２ CF ２ CF (CF ３ )CF ２ CF ２ ) -, -(OCF ２ CF ２ CF ２ CF (CF ３ )CF ２ )-, and -(OCF ２ CF ２ CF ２ CF ２ CF (CF ３))-. ５ F １０ )- is -(OCF ２ CF ２ CF ２ CF ２ CF ２ )-,-(OCF(CF ３ )CF ２ CF ２ CF ２ ) -, -(OCF ２ CF (CF ３ )CF ２ CF ２ ) -, -(OCF ２ CF ２ CF (CF ３ )CF ２ )-, and -(OCF ２ CF ２ CF ２ CF (CF ３ ))-. ４ F ８ )- is -(OCF ２ CF ２ CF ２ CF ２ )-,-(OCF(CF ３ )CF ２ CF ２ ) -, -(OCF ２ CF (CF ３ )CF ２ ) -, -(OCF ２ CF ２ CF (CF ３ )) -, -(OC(CF ３ ) ２ CF ２ ) -, -(OCF ２ C (CF ３ ) ２ )-,-(OCF(CF ３ )CF(CF ３ ))-,-(OCF(C ２ F ５ )CF ２ )-, and -(OCF ２ CF (C ２ F ５ ))-. ３ F ６) - (i.e., in the above formula (2), R Ｆａ is a fluorine atom), -(OCF ２ CF ２ CF ２ )-,-(OCF(CF ３ )CF ２ )-, and -(OCF ２ CF (CF ３ ))-. ２ F ４ )- is -(OCF ２ CF ２ )-, and -(OCF(CF ３ ))-.

[0024] In one embodiment, R Ｆ may be, independently in each occurrence, a group represented by any one of the following formulas (2-1) to (2-5):

[0025] - (OC ３ F ６ ) ｄ - (OC ２ F ４ ) ｅ - (2-1) [In formula (2-1), d is an integer of 1 to 200, and e is 0 or 1.]

[0026] - (OC ４ F ８ ) ｃ - (OC ３ F ６ ) ｄ - (OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2-2) [In formula (2-2), c and d each independently represent an integer of 0 or more and 30 or less, e and f each independently represent an integer of 1 or more and 200 or less, the sum of c, d, e, and f is 2 or more, and the order of occurrence of each repeating unit enclosed in parentheses with the subscript c, d, e, or f is arbitrary in the formula.],

[0027] - (R ６ -R ７ ) ｇ- (2-3) [In formula (2-3), R ６ is OCF ２ or O.C. ２ F ４ and R ７ is O.C. ２ F ４ , O.C. ３ F ６ , O.C. ４ F ８ , O.C. ５ F １０ and O.C. ６ F １２ or a combination of two or three groups selected from these groups, and g is an integer from 2 to 100;

[0028] - (OC ６ F １２ ) ａ - (OC ５ F １０ ) ｂ - (OC ４ F ８ ) ｃ - (OC ３ F ６ ) ｄ - (OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2-4) [In formula (2-4), e represents an integer of 1 or more and 200 or less, a, b, c, d, and f each independently represent an integer of 0 or more and 200 or less, and the order of the repeating units enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula.]

[0029] - (OC ６ F １２ ) ａ - (OC ５ F １０ ) ｂ - (OC ４ F ８ ) ｃ - (OC ３ F ６ ) ｄ - (OC ２ F ４ ) ｅ -(OCF２ ) ｆ - (2-5) [In formula (2-5), f represents an integer of 1 or more and 200 or less, a, b, c, d, and e each independently represent an integer of 0 or more and 200 or less, and the order of the repeating units enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula.]

[0030] In the above formula (2-1), d is preferably an integer of 5 to 200, more preferably 10 to 100, and even more preferably 15 to 50, for example, an integer of 25 to 35. The above formula (2-1) is preferably -(OCF ２ CF ２ CF ２ ) ｄ -, or -(OCF(CF ３ )CF ２ ) ｄ -, and more preferably -(OCF ２ CF ２ CF ２ ) ｄ In one embodiment, e is 0. In another embodiment, e is 1.

[0031] In the formula (2-2), e and f are each independently an integer of preferably 5 to 200, more preferably 10 to 200. The sum of c, d, e, and f is preferably 5 or more, more preferably 10 or more, and may be, for example, 15 or more or 20 or more. In one aspect, the formula (2-2) is preferably -(OCF ２ CF ２ CF ２ CF ２ ) ｃ -(OCF ２ CF ２ CF ２ ) ｄ -(OCF ２ CF ２ ) ｅ -(OCF ２ ) ｆ In another embodiment, formula (2-2) is a group represented by -(OC ２ F ４ ) ｅ -(OCF ２ )ｆ It may be a group represented by -.

[0032] In the above formula (2-3), R ６ is preferably OC ２ F ４ In the above (2-3), R ７ is preferably OC ２ F ４ , O.C. ３ F ６ and O.C. ４ F ８ or a combination of two or three groups independently selected from these groups, more preferably OC ３ F ６ and O.C. ４ F ８ is a group selected from ２ F ４ , O.C. ３ F ６ and O.C. ４ F ８ The combination of two or three groups independently selected from the group consisting of, but not limited to, —OC ２ F ４ O.C. ３ F ６ -, -OC ２ F ４ O.C. ４ F ８ -, -OC ３ F ６ O.C. ２ F ４ -, -OC ３ F ６ O.C. ３ F ６ -, -OC ３ F ６ O.C. ４ F ８ -, -OC ４ F ８ O.C. ４ F ８ -, -OC ４ F ８ O.C. ３ F ６ -, -OC ４ F ８ O.C. ２ F ４ -, -OC２ F ４ O.C. ２ F ４ O.C. ３ F ６ -, -OC ２ F ４ O.C. ２ F ４ O.C. ４ F ８ -, -OC ２ F ４ O.C. ３ F ６ O.C. ２ F ４ -, -OC ２ F ４ O.C. ３ F ６ O.C. ３ F ６ -, -OC ２ F ４ O.C. ４ F ８ O.C. ２ F ４ -, -OC ３ F ６ O.C. ２ F ４ O.C. ２ F ４ -, -OC ３ F ６ O.C. ２ F ４ O.C. ３ F ６ -, -OC ３ F ６ O.C. ３ F ６ O.C. ２ F ４ - and -OC ４ F ８ O.C. ２ F ４ O.C. ２ F ４ In the above formula (2-3), g is preferably an integer of 3 or more, more preferably an integer of 5 or more. The above g is preferably an integer of 50 or less. In the above formula (2-3), OC ２ F ４ , O.C. ３ F ６ , O.C. ４ F ８ , O.C. ５ F１０、 and O.C. ６ F １２ may be either a straight chain or a branched chain, and is preferably a straight chain. In this embodiment, the above formula (2-3) is preferably -(OC ２ F ４ -OC ３ F ６ ) ｇ -, or - (OC ２ F ４ -OC ４ F ８ ) ｇ - is.

[0033] In the above formula (2-4), e is preferably an integer of 1 or more and 100 or less, more preferably an integer of 5 or more and 100 or less. The sum of a, b, c, d, e, and f is preferably 5 or more, more preferably 10 or more, for example, 10 or more and 100 or less.

[0034] In the above formula (2-5), f is preferably an integer of 1 or more and 100 or less, more preferably an integer of 5 or more and 100 or less. The sum of a, b, c, d, e, and f is preferably 5 or more, more preferably 10 or more, for example, 10 or more and 100 or less.

[0035] In one embodiment, the R Ｆ is a group represented by the above formula (2-1).

[0036] In one embodiment, the R Ｆ is a group represented by the above formula (2-2).

[0037] In one embodiment, the R Ｆ is a group represented by the above formula (2-3).

[0038] In one embodiment, the R Ｆ is a group represented by the above formula (2-4).

[0039] In one embodiment, the R Ｆ is a group represented by the above formula (2-5).

[0040] R ＦIn the formula, the ratio of e to f (hereinafter referred to as the "e / f ratio") may be 0.5 to 4, preferably 0.6 to 3, more preferably 0.7 to 2, and even more preferably 0.8 to 1.4. By setting the e / f ratio to 4 or less, the lubricity and chemical stability are further improved. The smaller the e / f ratio, the more the lubricity is improved. On the other hand, by setting the e / f ratio to 0.5 or more, the stability of the compound can be further increased. The larger the e / f ratio, the more the stability of the fluoropolyether structure is improved. In this case, the value of f is preferably 0.8 or more.

[0041] In one embodiment, the R Ｆ is represented by the following formula (2-6): -(OCF ２ CF ２ CF ２ ) ａ -(OCF(CF ３ )CF ２ ) ｂ -(OCF ２ CF (CF ３ )) ｃ -(OCF ２ CF ２ ) ｄ -(OCF(CF ３ )) ｅ -(OCF ２ ) ｆ - (2-6) [In formula (2-6), a, b, c, d, e, and f each independently represent an integer of 0 to 200, the sum of a, b, c, d, e, and f is 1 or more, and the order of the repeating units enclosed in parentheses after a, b, c, d, e, or f is arbitrary in the formula.]

[0042] In one embodiment, the R Ｆ is represented by the following formula (2-7): -(OCF ２ CF ２ ) ｄ -(OCF(CF ３ )) ｅ -(OCF ２ ) ｆ- (2-7) [In formula (2-7), d, e, and f each independently represent an integer of 0 to 200, the sum of d, e, and f is 1 or more, and the order of the repeating units enclosed in parentheses with d, e, or f is arbitrary in the formula.]

[0043] R Ｆ In the formula, the ratio of d to f (hereinafter referred to as the "d / f ratio") may be 0.5 to 4, preferably 0.6 to 3, more preferably 0.7 to 2, and even more preferably 0.8 to 1.4. By setting the d / f ratio to 4 or less, the lubricity and chemical stability are further improved. The smaller the d / f ratio, the more the lubricity is improved. On the other hand, by setting the d / f ratio to 0.5 or more, the stability of the compound can be further increased. The larger the d / f ratio, the more the stability of the fluoropolyether structure is improved. In this case, the value of f is preferably 0.8 or more.

[0044] According to the findings of the present inventors, when the number of carbon atoms in the perfluorooxyalkylene unit in PFPE is 2 or less, the solubility of the lithium salt in PFPE is further increased. Ｆ When R is represented by the above formula (2-7), a higher effect can be expected. Ｆ is represented by the above formula (2-7), the number of ether bonds in PFPE increases. It is believed that a large number of ether bonds in PFPE makes it easier for lithium ions to coordinate with PFPE. This is believed to improve the solubility of lithium salts in PFPE.

[0045] In the above fluoropolyether group-containing compound, R Ｆ The number average molecular weight of the portion is not particularly limited, but is, for example, 500 to 30,000, preferably 1,500 to 30,000, and more preferably 2,000 to 10,000. Ｆ The number average molecular weight of １９ The value is measured by F-NMR.

[0046] 1.2 LiI dissolved in PFPE According to the findings of the present inventors, PFPE itself does not have lithium ion conductivity, so when PFPE is mixed with battery materials, PFPE tends to become a battery resistor. To address this issue, the present inventors thought that dissolving a lithium salt in PFPE might enable PFPE to exhibit lithium ion conductivity.

[0047] Examples of lithium salts that can be used as battery materials include halides (LiF, LiCl, LiBr, LiI) and imide salts (LiTFSI). According to the findings of the present inventors, among many lithium salts, LiI is particularly soluble in the above-mentioned PFPE and easily exhibits lithium ion conductivity in the PFPE. Iodine has a lower electronegativity than fluorine, chlorine, and bromine. That is, LiI has the property of easily dissociating lithium ions compared to LiF, LiCl, and LiBr, and is therefore thought to have a higher solubility in the above-mentioned PFPE.

[0048] The concentration of LiI in PFPE is not particularly limited and may be appropriately adjusted depending on the desired lithium ion conductivity. For example, the molar concentration of LiI in PFPE may be 0.01 M or more, 0.02 M or more, 0.03 M or more, 0.04 M or more, or 0.05 M or more, and may be less than or equal to the saturated concentration.

[0049] Whether LiI is dissolved in PFPE can be determined by analyzing the components (elements, ions) dissolved in PFPE. Here, LiI is not necessarily completely dissociated into lithium ions and iodine ions in PFPE, and may exist as some kind of association complex. In any case, dissolving LiI in PFPE can cause PFPE to exhibit lithium ion conductivity.

[0050] In this application, "LiI dissolved in PFPE" is not limited to a state in which LiI, a lithium salt, is added to PFPE and dissolved therein, but also includes a state in which LiI is dissolved in PFPE as a result of adding a Li source and an I source separately to PFPE and dissolving them.

[0051] 1.3 Other Components The lithium ion conductive material of the present disclosure may contain other additive components in addition to the above-mentioned PFPE and LiI. Various other additive components can be adopted depending on the desired performance.

[0052] 2. Secondary Battery The technology of the present disclosure also has an aspect of a secondary battery having the above-described lithium ion conductive material. That is, as shown in Fig. 1, a secondary battery 100 according to one embodiment has a positive electrode 10, an electrolyte layer 20, and a negative electrode 30, and at least one of the positive electrode 10, the electrolyte layer 20, and the negative electrode 30 contains the above-described lithium ion conductive material of the present disclosure.

[0053] 2.1 Positive Electrode The positive electrode 10 may be any electrode capable of functioning appropriately as a positive electrode for a secondary battery, and its configuration is not particularly limited. As shown in FIG. 1 , the positive electrode 10 may include a positive electrode active material layer 11 and a positive electrode current collector 12.

[0054] 2.1.1 Positive Electrode Active Material Layer The positive electrode active material layer 11 contains at least a positive electrode active material and may further contain, optionally, an electrolyte, a conductive additive, a binder, and the like. The positive electrode active material layer 11 may also contain various additives. The content of each component in the positive electrode active material layer 11 may be appropriately determined depending on the desired battery performance. For example, the content of the positive electrode active material may be 40% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more, or 100% by mass or less, or 90% by mass or less, where the total weight of the positive electrode active material layer 11 (total solid content) is taken as 100% by mass. The shape of the positive electrode active material layer 11 is not particularly limited, and may be, for example, a sheet-like positive electrode active material layer having a substantially flat surface. The thickness of the positive electrode active material layer 11 is not particularly limited, and may be, for example, 0.1 μm or more, 1 μm or more, or 10 μm or more, and may be 2 mm or less, 1 mm or less, or 500 μm or less.

[0055] As the positive electrode active material, any known positive electrode active material for secondary batteries may be used. Among known active materials, a material having a relatively noble potential (charge / discharge potential) for absorbing and releasing lithium ions can be used as the positive electrode active material, and a material having a relatively base potential can be used as the negative electrode active material described below. The positive electrode active material may be, for example, at least one selected from various lithium-containing compounds, elemental sulfur, sulfur compounds, etc. Examples of lithium-containing compounds as the positive electrode active material include lithium cobalt oxide, lithium nickel oxide, Li １±α Ni １／３ Co １／３ Mn １／３ O ２±δ , lithium manganate, spinel-based lithium compounds (Li １＋ｘ Mn ２－ｘ－ｙ M ｙ O ４ (wherein M is one or more selected from Al, Mg, Co, Fe, Ni, and Zn)), lithium titanate, lithium metal phosphate (LiMPO ４ and the like, where M is one or more selected from Fe, Mn, Co, and Ni). In particular, when the positive electrode active material contains a lithium-containing oxide containing at least Li, at least one of Ni, Co, and Mn, and O as constituent elements, a higher effect can be expected. Only one type of positive electrode active material may be used alone, or two or more types may be used in combination.

[0056] The shape of the positive electrode active material may be any shape commonly used for positive electrode active materials in batteries. The positive electrode active material may be, for example, particulate. The positive electrode active material may be hollow, voided, or porous. The positive electrode active material may be primary particles or secondary particles formed by aggregation of multiple primary particles. The average particle diameter D50 of the positive electrode active material may be, for example, 1 nm or more, 5 nm or more, or 10 nm or more, or 500 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. The average particle diameter D50 referred to in this application is the particle diameter (median diameter) at 50% of the integrated value in a volume-based particle size distribution determined by a laser diffraction / scattering method.

[0057] A protective layer containing an ion-conductive oxide may be formed on the surface of the positive electrode active material. This makes it easier to suppress the reaction between the positive electrode active material and a sulfide (for example, a sulfide solid electrolyte described later). Examples of the ion-conductive oxide include Li ３ BO ３ , LiBO ２ , Li ２ CO ３ , LiAlO ２ , Li ４ SiO ４ , Li ２ SiO ３ , Li ３ P.O. ４ , Li ２ SO ４ , Li ２ TiO ３ , Li ４ Ti ５ O １２ , Li ２ Ti ２ O ５ , Li ２ ZrO ３ , LiNbO ３ , Li ２ MoO ４ , Li ２ WO ４ Examples of the ion-conductive oxide include oxides in which some elements are substituted with doping elements such as P or B. The coverage (area ratio) of the protective layer with respect to the surface of the positive electrode active material may be, for example, 70% or more, 80% or more, or 90% or more. The thickness of the protective layer may be, for example, 0.1 nm or more or 1 nm or more, and may be 100 nm or less or 20 nm or less.

[0058] The electrolyte that can be contained in the positive electrode active material layer 11 may be a solid electrolyte, a liquid electrolyte (electrolytic solution), or a combination thereof. In particular, when the positive electrode active material layer 11 contains at least a solid electrolyte as the electrolyte, a high effect is likely to be obtained. Furthermore, when the positive electrode active material layer 11 contains at least a solid electrolyte and the lithium ion conductive material of the present disclosure as the electrolyte, an even higher effect is likely to be obtained.

[0059] The solid electrolyte may be any known solid electrolyte for secondary batteries. The solid electrolyte may be an inorganic solid electrolyte or an organic polymer electrolyte. In particular, inorganic solid electrolytes have excellent ionic conductivity and heat resistance. Examples of inorganic solid electrolytes include lithium lanthanum zirconate, LiPON, and Li １＋Ｘ Al Ｘ Ge ２－Ｘ (P.O. ４ ) ３ oxide solid electrolytes such as Li—SiO-based glass and Li—Al—S—O-based glass; Li ２ S-P ２ S ５ , Li ２ S-SiS ２ , LiI-Li ２ S-SiS ２ , LiI-Si ２ S-P ２ S ５ , Li ２ S-P ２ S ５ -LiI-LiBr, LiI-Li ２ S-P ２ S ５ , LiI-Li ２ S-P ２ O ５ , LiI-Li ３ P.O. ４ -P ２ S ５ , Li ２ S-P ２ S ５ -GeS ２ Examples of sulfide solid electrolytes include sulfide solid electrolytes such as those described above. In particular, sulfide solid electrolytes, especially sulfide solid electrolytes containing at least Li, S, and P as constituent elements, have high performance. The solid electrolyte may be amorphous or crystalline. The solid electrolyte may be, for example, particulate. Only one type of solid electrolyte may be used alone, or two or more types may be used in combination.

[0060] The electrolyte may contain a predetermined carrier ion (e.g., lithium ion). The electrolyte may be, for example, a non-aqueous electrolyte. The composition of the electrolyte may be the same as that of a known electrolyte for a secondary battery. For example, the electrolyte may be a solution in which a lithium salt is dissolved in a carbonate-based solvent at a predetermined concentration. Examples of carbonate-based solvents include fluoroethylene carbonate (FEC), ethylene carbonate (EC), and dimethyl carbonate (DMC). Examples of lithium salts include LiPF ６ etc.

[0061] Examples of conductive additives that can be contained in the positive electrode active material layer 11 include carbon materials such as vapor grown carbon fiber (VGCF), acetylene black (AB), ketjen black (KB), carbon nanotubes (CNT), and carbon nanofibers (CNF); and metal materials such as nickel, aluminum, and stainless steel. The conductive additive may be, for example, particulate or fibrous, and its size is not particularly limited. Only one type of conductive additive may be used alone, or two or more types may be used in combination.

[0062] Examples of binders that can be contained in the positive electrode active material layer 11 include butadiene rubber (BR)-based binders, butylene rubber (IIR)-based binders, acrylate butadiene rubber (ABR)-based binders, styrene butadiene rubber (SBR)-based binders, polyvinylidene fluoride (PVdF)-based binders, polytetrafluoroethylene (PTFE)-based binders, polyimide (PI)-based binders, etc. Only one type of binder may be used alone, or two or more types may be used in combination.

[0063] 2.1.2 Positive Electrode Current Collector As shown in FIG. 1 , the positive electrode 10 may include a positive electrode current collector 12 in contact with the positive electrode active material layer 11. Any common positive electrode current collector for batteries can be used as the positive electrode current collector 12. The positive electrode current collector 12 may be in the form of a foil, plate, mesh, punched metal, foam, or the like. The positive electrode current collector 12 may be composed of a metal foil or metal mesh. Metal foils are particularly advantageous in terms of ease of handling. The positive electrode current collector 12 may be composed of multiple foils. Examples of metals that may constitute the positive electrode current collector 12 include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, and the like. In particular, the positive electrode current collector 12 may contain Al from the viewpoint of ensuring oxidation resistance. The positive electrode current collector 12 may have some kind of coating layer on its surface for the purpose of adjusting the resistance, etc. Furthermore, the positive electrode current collector 12 may be a metal foil or a substrate on which the above-mentioned metal is plated or vapor-deposited. Furthermore, when the positive electrode current collector 12 is made of multiple sheets of metal foil, some kind of layer may be present between the multiple sheets of metal foil. The thickness of the positive electrode current collector 12 is not particularly limited. For example, it may be 0.1 μm or more or 1 μm or more, or may be 1 mm or less or 100 μm or less.

[0064] 2.2 Electrolyte Layer The electrolyte layer 20 is disposed between the positive electrode 10 and the negative electrode 30 and can function as a separator. The electrolyte layer 20 contains at least an electrolyte and may further contain, optionally, a binder or the like. The electrolyte layer 20 may also contain various other additives. The content of each component in the electrolyte layer 20 is not particularly limited and may be determined appropriately depending on the desired battery performance. The shape of the electrolyte layer 20 is not particularly limited and may be, for example, a sheet-like shape having a substantially flat surface. The thickness of the electrolyte layer 20 is not particularly limited and may be, for example, 0.1 μm or more or 1 μm or more, and may be 2 mm or less or 1 mm or less.

[0065] 2.2.1 Electrolyte The electrolyte contained in the electrolyte layer 20 may be appropriately selected from the electrolytes exemplified above as those that can be contained in the positive electrode active material layer. In particular, the electrolyte layer 20 containing a solid electrolyte, particularly a sulfide solid electrolyte, and even more particularly, a sulfide solid electrolyte containing at least Li, S, and P as constituent elements, exhibits high performance. Furthermore, when the electrolyte layer 20 contains at least a solid electrolyte and the lithium ion conductive material of the present disclosure as the electrolyte, even greater effects are likely to be obtained. When the electrolyte is a solid electrolyte, the solid electrolyte may be amorphous or crystalline. When the electrolyte is a solid electrolyte, the solid electrolyte may be, for example, particulate. Only one type of electrolyte may be used alone, or two or more types may be used in combination.

[0066] 2.2.2 Binder The binder that can be contained in the electrolyte layer 20 may be appropriately selected from, for example, the binders that can be contained in the positive electrode active material layer described above.

[0067] 2.3 Negative Electrode The negative electrode 30 may be any electrode capable of functioning appropriately as a negative electrode for a secondary battery, and its configuration is not particularly limited. As shown in FIG. 1 , the negative electrode 30 may include a negative electrode active material layer 31 and a negative electrode current collector 32.

[0068] 2.3.1 Negative Electrode Active Material Layer The negative electrode active material layer 31 contains at least a negative electrode active material and may further contain, optionally, an electrolyte, a conductive additive, a binder, and the like. The negative electrode active material layer 31 may also contain various additives. The content of each component in the negative electrode active material layer 31 may be appropriately determined depending on the desired battery performance. For example, the content of the negative electrode active material may be 40% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more, or 100% by mass or less, or 90% by mass or less, where the total weight of the negative electrode active material layer 31 (total solid content) is taken as 100% by mass. The shape of the negative electrode active material layer 31 is not particularly limited, and may be, for example, a sheet-like negative electrode active material layer having a substantially flat surface. The thickness of the negative electrode active material layer 31 is not particularly limited, and may be, for example, 0.1 μm or more, 1 μm or more, or 10 μm or more, and may be 2 mm or less, 1 mm or less, or 500 μm or less.

[0069] As the negative electrode active material, various materials can be used that have a lithium ion absorption / desorption potential (charge / discharge potential) that is lower than that of the above-mentioned positive electrode active material. For example, the negative electrode active material may be at least one selected from silicon-based active materials such as Si, Si alloys, and silicon oxide; carbon-based active materials such as graphite and hard carbon; various oxide-based active materials such as lithium titanate; metallic lithium, lithium alloys, etc. Only one type of negative electrode active material may be used alone, or two or more types may be used in combination.

[0070] The shape of the negative electrode active material may be any shape commonly used for negative electrode active materials in batteries. The negative electrode active material may be, for example, particulate. The negative electrode active material may be hollow, void-containing, or porous. The negative electrode active material may be primary particles or secondary particles formed by aggregation of multiple primary particles. The average particle diameter D50 of the negative electrode active material may be, for example, 1 nm or more, 5 nm or more, or 10 nm or more, and may be 500 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. Alternatively, the negative electrode active material may be in the form of a sheet (foil or film) such as lithium foil. That is, the negative electrode active material layer 31 may be made of a sheet of negative electrode active material.

[0071] The electrolyte that can be contained in the negative electrode active material layer 31 may be a solid electrolyte, a liquid electrolyte (electrolytic solution), or a combination thereof. In particular, when the negative electrode active material layer 31 contains at least a solid electrolyte as the electrolyte, a high effect is likely to be obtained. Furthermore, when the negative electrode active material layer 31 contains at least a solid electrolyte and the lithium ion conductive material of the present disclosure as the electrolyte, an even higher effect is likely to be obtained. The negative electrode active material layer 31 is preferably a solid electrolyte, particularly a sulfide solid electrolyte, and particularly a Li ２ S-P ２ S ５ The negative electrode active material layer 31 may contain a sulfide solid electrolyte containing the above-mentioned carbon material or metal material. The negative electrode active material layer 31 may contain a binder selected appropriately from the binders exemplified above as binders that can be contained in the positive electrode active material layer 11.

[0072] 2.3.2 Negative Electrode Current Collector As shown in FIG. 1 , the negative electrode 30 may include a negative electrode current collector 32 in contact with the negative electrode active material layer 31. Any of the negative electrode current collectors commonly used in batteries can be used as the negative electrode current collector 32. The negative electrode current collector 32 may be in the form of a foil, plate, mesh, punched metal, foam, or the like. The negative electrode current collector 32 may be a metal foil or metal mesh, or a carbon sheet. Metal foil is particularly advantageous in terms of ease of handling. The negative electrode current collector 32 may be composed of multiple foils or sheets. Examples of metals constituting the negative electrode current collector 32 include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. In particular, from the viewpoint of ensuring reduction resistance and being less likely to alloy with lithium, the negative electrode current collector 32 may contain at least one metal selected from Cu, Ni, and stainless steel. The negative electrode current collector 32 may have a coating layer on its surface for purposes such as adjusting resistance. The negative electrode current collector 32 may also be a metal foil or a substrate plated or vapor-deposited with the above metal. When the negative electrode current collector 32 is made of multiple sheets of metal foil, some layer may be present between the multiple sheets of metal foil. The thickness of the negative electrode current collector 32 is not particularly limited. For example, it may be 0.1 μm or more or 1 μm or more, or may be 1 mm or less or 100 μm or less.

[0073] 2.4 Lithium Ion Conductive Material In the secondary battery 100, the lithium ion conductive material of the present disclosure is contained in at least one of the positive electrode 10, the electrolyte layer 20, and the negative electrode 30. The lithium ion conductive material may, for example, fill at least a portion of the voids (gaps between solid materials) present in the positive electrode 10, the electrolyte layer 20, and the negative electrode 30. In the secondary battery 100, the sulfide solid electrolyte may be contained in at least one of the positive electrode 10, the electrolyte layer 20, and the negative electrode 30, and a portion of the lithium ion conductive material of the present disclosure may be in contact with a portion of the sulfide solid electrolyte. Here, since the secondary battery 100 employs PFPE, which has low reactivity with the sulfide solid electrolyte, even if the PFPE comes into contact with the sulfide solid electrolyte, alteration or deterioration of the sulfide solid electrolyte is unlikely to occur, and the high ionic conductivity of the sulfide solid electrolyte is likely to be maintained.

[0074] 2.5 Other Configurations The secondary battery 100 may have the above-described configurations housed inside an exterior body. Any known exterior body for a battery can be used as the exterior body. Furthermore, a plurality of secondary batteries 100 may be electrically connected and stacked in any manner to form an assembled battery. In this case, the assembled battery may be housed inside a known battery case. The secondary battery 100 may also have other obvious configurations such as necessary terminals. Examples of shapes of the secondary battery 100 include coin type, laminate type, cylindrical type, and square type.

[0075] 2.6 Method for Manufacturing Secondary Battery The secondary battery 100 can be manufactured by applying a known method. For example, it can be manufactured as follows. However, the manufacturing method of the secondary battery 100 is not limited to the method described below, and each layer may be formed by, for example, dry molding. (1) A negative electrode active material and the like that constitute the negative electrode active material layer are dispersed in a solvent to obtain a negative electrode slurry. The solvent used in this case is not particularly limited, and water or various organic solvents can be used. Thereafter, the negative electrode slurry is applied to the surface of the negative electrode current collector or the electrolyte layer described below using a doctor blade or the like, and then dried to form a negative electrode active material layer on the surface of the negative electrode current collector or the electrolyte layer, thereby forming a negative electrode. Here, the negative electrode active material layer may be press-molded. (2) A positive electrode slurry is obtained by dispersing a positive electrode active material and the like that constitute the positive electrode active material layer in a solvent. The solvent used in this case is not particularly limited, and water or various organic solvents can be used. The positive electrode slurry is then applied to the surface of a positive electrode current collector or an electrolyte layer (described later) using a doctor blade or the like, followed by drying to form a positive electrode active material layer on the surface of the positive electrode current collector or the electrolyte layer, thereby forming a positive electrode. The positive electrode active material layer may be press-molded. (3) The layers are stacked so that the electrolyte layer is sandwiched between the negative electrode and the positive electrode, thereby obtaining a laminate having the negative electrode current collector, the negative electrode active material layer, the electrolyte layer, the positive electrode active material layer, and the positive electrode current collector in this order. The electrolyte layer may be obtained, for example, by molding an electrolyte mixture containing an electrolyte and a binder, or by press-molding. Alternatively, when producing an electrolyte battery, a separator that will become the electrolyte layer may be sandwiched between the negative electrode active material layer and the positive electrode active material layer. The laminate may then be press-molded. Other components, such as terminals, may be attached to the laminate as needed. (4) The laminate, optionally together with an electrolyte solution, is housed in a battery case and sealed to obtain a secondary battery. The timing for incorporating the lithium ion conductive material of the present disclosure into at least one of the positive electrode, the electrolyte layer, and the negative electrode is not particularly limited, and may be, for example, one or more of the timings (1) to (3) above, or may be when the laminate is housed in a battery case or at any time thereafter.

[0076] The technology of the present disclosure will be described in more detail below with reference to examples, but the technology of the present disclosure is not limited to the following examples.

[0077] 1. Preparation of Lithium Ion Conductive Material A material for evaluation was prepared by mixing PFPE (I) or (II) as perfluoropolyether with one of lithium trifluoromethanesulfonylimide (LiTFSI), lithium fluoride (LiF), and lithium iodide (LiI) as a lithium salt. The concentration of the lithium salt relative to PFPE is as shown in Table 1 below. PFPE (I) is a compound represented by the following formula (I) (m / n is 1.2, number average molecular weight is 5120, terminal R is CF ３ and CF ２ CF ３ and PFPE(II) are liquids having a chemical structure represented by the following formula (II) (m / n is 1.3, number average molecular weight is 4238):

[0078]

[0079] 2. Measurement of Ion Conductivity The lithium ion conductivity of each evaluation material was confirmed by measuring the resistance using an AC impedance method.

[0080] 3. Evaluation of reactivity with lithium PFPE (I) or (II) was brought into contact with metallic lithium foil, and the presence or absence of discoloration was confirmed. If discoloration was confirmed, it can be said that PFPE reacted with lithium.

[0081] 4. Evaluation Results The evaluation results are shown in Table 1 below.

[0082]

[0083] The results shown in Table 1 reveal the following. (1) In Comparative Examples 1 to 4, because LiTFSI or LiF was used as the lithium salt, the lithium salt could not be properly dissolved in PFPE, and lithium ion conductivity could not be exhibited in PFPE. (2) In Examples 1 to 4, because LiI was used as the lithium salt, LiI could be dissolved in PFPE (I) or (II). As a result, lithium ion conductivity could be exhibited in PFPE. Furthermore, no reaction between PFPE and lithium was observed, and the PFPE was suitable as a lithium ion conductive material for, for example, secondary batteries.

[0084] In the above examples, PFPEs having specific chemical structures are exemplified, but the chemical structure of PFPE is not limited to this. Furthermore, the concentration of lithium salt in the lithium ion conductive material is not limited to the specific concentration described above.

[0085] As described above, a material containing a specific perfluoropolyether and LiI dissolved in the perfluoropolyether has lithium ion conductivity and low reactivity with lithium, and can be said to be suitable as a lithium ion conductive material in, for example, secondary batteries.

[0086] 10 Positive electrode 11 Positive electrode active material layer 12 Positive electrode current collector 20 Electrolyte layer 30 Negative electrode 31 Negative electrode active material layer 32 Negative electrode current collector 100 Secondary battery

Claims

1. A perfluoropolyether represented by the following formula (1), LiI dissolved in the perfluoropolyether; 1. A lithium ion conducting material comprising: E １ -Rf １ -R Ｆ -O-Rf ２ -E ２ (1) [In formula (1), Rf １ and Rf ２ each independently represents a C1-16 divalent alkylene group optionally substituted by one or more fluorine atoms, E １ and E ２ are each independently a monovalent group selected from the group consisting of a fluorine group, an aldehyde group, and a C1-10 alkyl ester group, R Ｆ is a divalent fluoropolyether group.

2. The R Ｆ is expressed by the formula (2): -(OC ６ F １２ ) ａ -(OC ５ F １０ ) ｂ -(OC ４ F ８ ) ｃ -(OC ３ R Ｆａ ６ ) ｄ -(OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2) [In formula (2), R Ｆａ is independently at each occurrence a hydrogen atom, a fluorine atom, or a chlorine atom; a, b, c, d, e, and f each independently represent an integer from 0 to 200; the sum of a, b, c, d, e, and f is greater than or equal to 1; The order of occurrence of each repeating unit enclosed in parentheses with a, b, c, d, e, or f in the formula is arbitrary. However, all R Ｆａ is a hydrogen atom or a chlorine atom, at least one of a, b, c, e and f is 1 or more. is a group represented by The lithium ion conducting material of claim 1.

3. The R Ｆａ is a fluorine atom, The lithium ion conductive material according to claim 2.

4. The R Ｆ each occurrence independently represents the following formula (2-1), (2-2), (2-3), (2-4) or (2-5): -(OC ３ F ６ ) ｄ -(OC ２ F ４ ) ｅ - (2-1) [In formula (2-1), d is an integer of 1 to 200, and e is 0 or 1.] -(OC ４ F ８ ) ｃ -(OC ３ F ６ ) ｄ -(OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2-2) [In formula (2-2), c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer from 1 to 200; The sum of c, d, e, and f is an integer from 10 to 200, The order of occurrence of each repeat unit enclosed in parentheses with the subscript c, d, e, or f is arbitrary in the formula. -(R ６ -R ７ ) ｇ - (2-3) [In formula (2-3), R ６ is O.C.F. ２ Or O.C. ２ F ４ and R ７ , O.C. ２ F ４ , O.C. ３ F ６ , O.C. ４ F ８ , O.C. ５ F １０ and O.C. ６ F １２ or a combination of two or three groups selected from these groups, g is an integer from 2 to 100. -(OC ６ F １２ ) ａ -(OC ５ F １０ ) ｂ -(OC ４ F ８ ) ｃ -(OC ３ F ６ ) ｄ -(OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2-4) [In formula (2-4), e represents an integer of 1 or more and 200 or less, a, b, c, d, and f each independently represent an integer of 0 to 200; The order of occurrence of each repeating unit enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula. -(OC ６ F １２ ) ａ -(OC ５ F １０ ) ｂ -(OC ４ F ８ ) ｃ -(OC ３ F ６ ) ｄ -(OC ２ F ４ ) ｅ -(OCF ２ ) ｆ - (2-5) [In formula (2-5), f represents an integer of 1 or more and 200 or less, a, b, c, d, and e each independently represent an integer of 0 to 200; The order of occurrence of each repeating unit enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula. is a group represented by The lithium ion conductive material according to claim 3.

5. The R Ｆ is expressed by the following formula (2-6): -(OCF ２ CF ２ CF ２ ) ａ -(OCF(CF ３ )CF ２ ) ｂ -(OCF ２ CF(CF ３ )) ｃ -(OCF ２ CF ２ ) ｄ -(OCF(CF ３ )) ｅ -(OCF ２ ) ｆ - (2-6) [In formula (2-6), a, b, c, d, e and f each independently represent an integer of 0 to 200, the sum of a, b, c, d, e, and f is greater than or equal to 1; The order of occurrence of each repeating unit enclosed in parentheses with a, b, c, d, e, or f is arbitrary in the formula. is a group represented by The lithium ion conductive material according to claim 4.

6. The R Ｆ is expressed by the following formula (2-7): -(OCF ２ CF ２ ) ｄ -(OCF(CF ３ )) ｅ -(OCF ２ ) ｆ - (2-7) [In formula (2-7), d, e and f each independently represent an integer of 0 to 200, the sum of d, e, and f is 1 or more; The order of occurrence of each repeating unit enclosed in parentheses with d, e, or f is arbitrary in the formula. is a group represented by The lithium ion conductive material according to claim 4.

7. The above E １ -Rf １ and the above E ２ -Rf ２ are each independently -CF ３ , -CF ２ CF ３ , and -CF ２ CF ２ CF ３ is a group selected from the group consisting of The lithium ion conductive material according to any one of claims 1 to 6.

8. A secondary battery having a positive electrode, an electrolyte layer, and a negative electrode, At least one of the positive electrode, the electrolyte layer and the negative electrode comprises the lithium ion conductive material according to any one of claims 1 to 7. Secondary battery.