Lithium ion conducting material and secondary battery

Abstract

Novel lithium ion conducting materials are disclosed. A lithium ion conducting material according to the present invention comprises a perfluoropolyether represented by formula (1) and LiI dissolved in the perfluoropolyether. E1-Rf1-RF-O-Rf2-E2 (1) [In formula (1), Rf1 and Rf2 each independently represent 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, 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, and RF is a divalent fluoropolyether group. ].

Description

Technical Field

[0001] The present application discloses a lithium ion conductive material and a secondary battery. Background Art

[0002] Patent Document 1 discloses that a perfluoropolyether is mixed as a texturing agent in a solid polymer electrolyte. In addition, Patent Document 2 discloses that a perfluoropolyether is an additive component of a non-aqueous electrolyte. Patent Document 3 discloses that a compound containing a perfluoropolyether group is present on the surface of an electrode in order to improve the storage property of the electrode.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2018-513539

[0006] Patent Document 2: Japanese Patent Application Publication No. 2018-200866

[0007] Patent Document 3: Japanese Patent Application Publication No. 2018-147887 Summary of the invention

[0008] Problems to be solved by the invention

[0009] As disclosed in Patent Documents 1 to 3, perfluoropolyether is used as various battery materials. However, perfluoropolyether itself does not have lithium ion conductivity, so when perfluoropolyether is used as a battery material, the resistance of the battery tends to increase. In this regard, a new technology that can make perfluoropolyether exhibit lithium ion conductivity is needed.

[0010] Furthermore, when using the lithium ion conductive material for various applications such as batteries is envisioned, the lithium ion conductive material is required to have low reactivity with lithium in addition to lithium ion conductivity.

[0011] Methods used to solve problems

[0012] The present application discloses the following multiple aspects as means for solving the above-mentioned problems.

[0013] <Method 1>

[0014] A lithium ion conductive material comprises a perfluoropolyether represented by the following formula (1) and LiI dissolved in the perfluoropolyether.

[0015] E1-Rf1-R F -O-Rf2-E2 (1)

[0016] [In formula (1), Rf1 and Rf2 are each independently a C1-16 divalent alkylene group which may be substituted with one or more fluorine atoms,

[0017] E1 and E2 are each independently a monovalent group selected from the group consisting of a fluoro 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,

[0018] R F is a divalent fluoropolyether group.]

[0019] <Method 2>

[0020] The lithium ion conductive material according to embodiment 1, wherein the R F It is a group represented by formula (2).

[0021] -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3R Fa 6) d -(OC2F4) e -(OCF2) f - (2)

[0022] [In formula (2), each occurrence of R Fa are each independently a hydrogen atom, a fluorine atom or a chlorine atom,

[0023] a, b, c, d, e and f are each independently an integer of 0 to 200,

[0024] The sum of a, b, c, d, e and f is greater than 1,

[0025] The order of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula.

[0026] Among them, in all R Fa When it is a hydrogen atom or a chlorine atom, at least one of a, b, c, e and f is 1 or more.]

[0027] <Method 3>

[0028] The lithium ion conductive material according to embodiment 2, wherein the R Fa A fluorine atom.

[0029] <Method 4>

[0030] The lithium ion conductive material according to Embodiment 3, wherein each occurrence of RF Each independently represents a group represented by the following formula (2-1), (2-2), (2-3), (2-4) or (2-5).

[0031] -(OC3F6) d -(OC2F4) e - (2-1)

[0032] [In formula (2-1), d is an integer of 1 to 200, and e is 0 or 1.]

[0033] -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-2)

[0034] [In formula (2-2), c and d are each independently an integer of 0 to 30,

[0035] e and f are each independently an integer of 1 to 200,

[0036] The sum of c, d, e and f is an integer from 10 to 200,

[0037] The order of presence of the repeating units marked with the subscript c, d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0038] -(R 6 -R 7 ) g - (2-3)

[0039] [In formula (2-3), R 6 For OCF2 or OC2F4,

[0040] R 7 is selected from OC2F4, OC3F6, OC4F8, OC5F 10 and OC6F 12 or a combination of two or three groups selected from these groups,

[0041] g is an integer from 2 to 100.]

[0042] -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-4)

[0043] [In formula (2-4), e is an integer of 1 to 200,

[0044] a, b, c, d and f are each independently an integer of 0 to 200,

[0045] The order of presence of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0046] -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-5)

[0047] [In formula (2-5), f is an integer of 1 to 200,

[0048] a, b, c, d and e are each independently an integer of 0 to 200,

[0049] The order of presence of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0050] <Method 5>

[0051] The lithium ion conductive material according to embodiment 4, wherein the R F It is a group represented by the following formula (2-6).

[0052] -(OCF2CF2CF2) a -(OCF(CF3)CF2) b -(OCF2CF(CF3)) c -(OCF2CF2) d -(OCF(CF3)) e -(OCF2) f - (2-6)

[0053] [In formula (2-6), a, b, c, d, e and f are each independently an integer of 0 to 200,

[0054] The sum of a, b, c, d, e and f is greater than 1,

[0055] The order of presence of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0056] <Method 6>

[0057] The lithium ion conductive material according to embodiment 4, wherein the R F It is a group represented by the following formula (2-7).

[0058] -(OCF2CF2) d -(OCF(CF3)) e -(OCF2) f - (2-7)

[0059] [In formula (2-7), d, e and f are each independently an integer of 0 to 200,

[0060] The sum of d, e and f is greater than 1,

[0061] The order of presence of the repeating units marked with d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0062] <Method 7>

[0063] The lithium ion conductive material according to any one of aspects 1 to 6, wherein the E1-Rf1 and the E2-Rf2 are each independently a group selected from the group consisting of -CF3, -CF2CF3 and -CF2CF2CF3.

[0064] <Method 8>

[0065] A secondary battery comprises 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 contains the lithium ion conductive material according to any one of aspects 1 to 7.

[0066] Effects of the Invention

[0067] According to the technology of the present invention, it is possible to make perfluoropolyether exhibit lithium ion conductivity. The lithium ion conductive material of the present invention has lithium ion conductivity, but has low reactivity to lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 An example of the configuration of a secondary battery is schematically shown. DETAILED DESCRIPTION

[0069] 1. Lithium ion conductive materials

[0070] Embodiments of the technology of the present invention will be described below, but the technology of the present invention is not limited to the following embodiments. The lithium ion conductive material of the present invention includes a perfluoropolyether represented by the following formula (1) and LiI dissolved in the perfluoropolyether.

[0071] 1.1 Perfluoropolyether (PFPE)

[0072] Perfluoropolyether (PFPE) can be a structural modifier that changes the mechanical properties of battery materials. According to the new insights of the inventors, when solid battery materials (active materials, solid electrolytes, conductive materials, etc.) are mixed with PFPE, for example, the fluidity of the battery material is improved by the lubricating effect produced by PFPE, and the filling rate of the battery material when the battery material is formed is easily increased. In addition, it is believed that PFPE has a high affinity for various battery materials due to its multiple ether bonds, and it is easy to exist appropriately with the battery material. In addition, PFPE has insulating properties, so for example, by including PFPE in the separator layer (electrolyte layer) of the battery, the voltage resistance of the separator layer can be improved.

[0073] The perfluoropolyether is represented by the following formula (1).

[0074] E1-Rf1-R F -O-Rf2-E2 (1)

[0075] [In formula (1), Rf1 and Rf2 are each independently a C1-16 divalent alkylene group which may be substituted with one or more fluorine atoms,

[0076] E1 and E2 are each independently a monovalent group selected from the group consisting of a fluoro 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,

[0077] R F is a divalent fluoropolyether group.]

[0078] In the above formula (1), Rf1 and Rf2 are each independently a C1-16 divalent alkylene group which may be substituted with one or more fluorine atoms.

[0079] In one embodiment, the "C1-16 divalent alkylene" in the above-mentioned C1-16 divalent alkylene which may be substituted with one or more fluorine atoms may be a linear or branched chain, preferably a linear or branched C1-6 alkyl alkylene, particularly a C1-3 alkylene, more preferably a linear C1-6 alkylene, particularly a C1-3 alkylene.

[0080] In one embodiment, the "C1-16 divalent alkylene group" in the above-mentioned C1-16 divalent alkylene group which may be substituted with one or more fluorine atoms may be a linear or branched group, and is preferably a linear or branched C1-6 fluoroalkylene group, in particular a C1-3 fluoroalkylene group, and specifically -CF2CH2- and -CF2CF2CH2-. In addition, a linear C1-6 perfluoroalkylene group, in particular a C1-3 perfluoroalkylene group, and specifically a group selected from the group consisting of -CF2-, -CF2CF2- and -CF2CF2CF2- is more preferred.

[0081] In the above formula (1), E1 and E2 are each independently a monovalent group selected from the group consisting of a fluoro 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.

[0082] The above PFPE has low reactivity to lithium. In particular, when the PFPE has a non-polar group as an end group, the reactivity to lithium can be further suppressed. In this regard, the above E1 and E2 are each independently preferably a fluoro group. In one embodiment, E1-Rf1 and E2-Rf2 are each independently a group selected from the group consisting of -CF3, -CF2CF3 and -CF2CF2CF3.

[0083] In the above formula (1), each occurrence of R F Each is independently a divalent fluoropolyether group.

[0084] R F Preferred is a group represented by formula (2).

[0085] -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3R Fa 6) d -(OC2F4) e -(OCF2) f - (2)

[0086] [In formula (2): Each occurrence of R Fa are each independently a hydrogen atom, a fluorine atom or a chlorine atom,

[0087] a, b, c, d, e and f are each independently an integer of 0 to 200,

[0088] The sum of a, b, c, d, e and f is greater than 1,

[0089] The order of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula.

[0090] Among them, in all R Fa When it is a hydrogen atom or a chlorine atom, at least one of a, b, c, e and f is 1 or more.]

[0091] R Fa It is preferably a hydrogen atom or a fluorine atom, and more preferably a fluorine atom.

[0092] Preferably, a, b, c, d, e and f are each independently an integer of 0 to 100.

[0093] The sum of a, b, c, d, e and f is preferably 5 or more, more preferably 10 or more, 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, further preferably 60 or less, for example, 50 or less or 30 or less.

[0094] These repeating units can be straight chain or branched chain. For example,

[0095] -(OC6F 12 )- can be any of -(OCF2CF2CF2CF2CF2CF2)-, -(OCF(CF3)CF2CF2CF2CF2)-, -(OCF2CF(CF3)CF2CF2CF2)-, -(OCF2CF2CF(CF3)CF2CF2CF2)-, -(OCF2CF2CF(CF3)CF2CF2)-, -(OCF2CF2CF2CF(CF3)CF2)-, -(OCF2CF2CF2CF(CF3)CF2)- and -(OCF2CF2CF2CF2CF(CF3))-.

[0096] -(OC5F 10 )- can be any of -(OCF2CF2CF2CF2CF2)-, -(OCF(CF3)CF2CF2CF2)-, -(OCF2CF(CF3)CF2CF2)-, -(OCF2CF2CF(CF3)CF2)-, -(OCF2CF2CF(CF3)CF2)- and -(OCF2CF2CF2CF(CF3))-.

[0097] -(OC4F8)- can be any one of -(OCF2CF2CF2CF2)-, -(OCF(CF3)CF2CF2)-, -(OCF2CF(CF3)CF2)-, -(OCF2CF2CF(CF3))-, -(OC(CF3)2CF2)-, -(OCF2C(CF3)2)-, -(OCF(CF3)CF(CF3))-, -(OCF(C2F5)CF2)- and -(OCF2CF(C2F5))-.

[0098] -(OC3F6)- (i.e., R Fa In the case of a fluorine atom), it may be any of -(OCF2CF2CF2)-, -(OCF(CF3)CF2)- and -(OCF2CF(CF3))-.

[0099] -(OC2F4)- can be any of -(OCF2CF2)- and -(OCF(CF3))-.

[0100] In one approach, each occurrence of R F Each independently may be a group represented by any one of the following formulae (2-1) to (2-5).

[0101] -(OC3F6) d -(OC2F4) e - (2-1)

[0102] [In formula (2-1), d is an integer of 1 to 200, and e is 0 or 1.]

[0103] -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-2)

[0104] [In formula (2-2), c and d are each independently an integer of 0 to 30,

[0105] e and f are each independently an integer of 1 to 200,

[0106] The sum of c, d, e and f is greater than 2,

[0107] The order of presence of the repeating units marked with the subscript c, d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0108] -(R 6 -R 7 ) g - (2-3)

[0109] [In formula (2-3), R 6 For OCF2 or OC2F4,

[0110] R 7 is selected from OC2F4, OC3F6, OC4F8, OC5F 10 and OC6F 12 or a combination of two or three groups selected from these groups,

[0111] g is an integer from 2 to 100.]

[0112] -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-4)

[0113] [In formula (2-4), e is an integer of 1 to 200,

[0114] a, b, c, d and f are each independently an integer of 0 to 200,

[0115] The order of presence of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0116] -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-5)

[0117] [In formula (2-5), f is an integer of 1 to 200,

[0118] a, b, c, d and e are each independently an integer of 0 to 200,

[0119] The order of presence of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0120] In the above formula (2-1), d is preferably 5 to 200, more preferably 10 to 100, further preferably 15 to 50, for example, an integer of 25 to 35. The above formula (2-1) is preferably -(OCF2CF2CF2) d -or-(OCF(CF3)CF2) d -, more preferably -(OCF2CF2CF2) d In one embodiment, e is 0. In another embodiment, e is 1.

[0121] In the above formula (2-2), e and f are each independently preferably an integer of 5 to 200, more preferably an integer of 10 to 200. In addition, the sum of c, d, e and f is preferably 5 or more, more preferably 10 or more, for example, 15 or more or 20 or more. In one embodiment, the above formula (2-2) is preferably -(OCF2CF2CF2CF2) c -(OCF2CF2CF2) d -(OCF2CF2) e -(OCF2) f In another embodiment, formula (2-2) may be -(OC2F4) e -(OCF2) f -represented group.

[0122] In the above formula (2-3), R 6 Preferably, it is OC2F4. In the above (2-3), R 7 It is preferably a group selected from OC2F4, OC3F6 and OC4F8 or a combination of two or three groups independently selected from these groups, and more preferably a group selected from OC3F6 and OC4F8. There is no particular limitation on the combination of two or three groups independently selected from OC2F4, OC3F6 and OC4F8, and examples thereof include: -OC2F4OC3F6-, -OC2F4OC4F8-, -OC3F6OC2F4-, -OC3F6OC3F6-, -OC3F6OC4F8-, -OC4F8OC4F8-, -OC4F8OC3F6-, -OC4F8OC2F4-, -OC2 F4OC2F4OC3F6-, -OC2F4OC2F4OC4F8-, -OC2F4OC3F6OC2F4-, -OC2F4OC3F6OC3F6-, -OC2F4OC4F8OC2F4-, -OC3F6OC2F4OC2F4-, -OC3F6OC2F4OC3F6-, -OC3F6OC3F6OC2F4- and -OC4F8OC2F4OC2F4-. In the above formula (2-3), g is preferably an integer greater than or equal to 3, and more preferably an integer greater than or equal to 5. The above g is preferably an integer less than or equal to 50. In the above formula (2-3), OC2F4, OC3F6, OC4F8, OC5F 10 and OC6F 12 It may be either a straight chain or a branched chain, preferably a straight chain. In this embodiment, the above formula (2-3) is preferably -(OC2F4-OC3F6) g -or-(OC2F4-OC4F8) g -.

[0123] In the above formula (2-4), e is preferably an integer of 1 to 100, more preferably an integer of 5 to 100. 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.

[0124] In the above formula (2-5), f is preferably an integer of 1 to 100, more preferably an integer of 5 to 100. 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.

[0125] In one embodiment, the above R F It is a group represented by the above formula (2-1).

[0126] In one embodiment, the above R F It is a group represented by the above formula (2-2).

[0127] In one embodiment, the above R F It is a group represented by the above formula (2-3).

[0128] In one embodiment, the above R F It is a group represented by the above formula (2-4).

[0129] In one embodiment, the above R F It is a group represented by the above formula (2-5).

[0130] In R F In the embodiment of the present invention, the ratio of e to f (hereinafter referred to as "e / f ratio") can 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, lubricity and chemical stability are further improved. The smaller the e / f ratio, the further 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 improved. The larger the e / f ratio, the further the stability of the fluoropolyether structure is improved. In this case, the value of f is preferably 0.8 or more.

[0131] In one embodiment, the above R F It may be a group represented by the following formula (2-6).

[0132] -(OCF2CF2CF2) a -(OCF(CF3)CF2) b -(OCF2CF(CF3)) c -(OCF2CF2) d -(OCF(CF3)) e -(OCF2) f- (2-6)

[0133] [In formula (2-6), a, b, c, d, e and f are each independently an integer of 0 to 200,

[0134] The sum of a, b, c, d, e and f is greater than 1,

[0135] The order of presence of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0136] In one embodiment, the above R F It may be a group represented by the following formula (2-7).

[0137] -(OCF2CF2) d -(OCF(CF3)) e -(OCF2) f - (2-7)

[0138] [In formula (2-7), d, e and f are each independently an integer of 0 to 200,

[0139] The sum of d, e and f is greater than 1,

[0140] The order of presence of the repeating units marked with d, e or f and enclosed in parentheses is arbitrary in the formula.]

[0141] In R F In the formula (hereinafter referred to as "d / f ratio"), the ratio of d to f can 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, lubricity and chemical stability are further improved. The smaller the d / f ratio, the further 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 improved. The larger the d / f ratio, the further the stability of the fluoropolyether structure is improved. In this case, the value of f is preferably 0.8 or more.

[0142] 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 improved. F When represented by the above formula (2-7), a higher effect can be expected. F In the case represented by the above formula (2-7), the number of ether bonds in PFPE increases. It is believed that when the number of ether bonds in PFPE is large, lithium ions are more easily coordinated to PFPE. Therefore, it is believed that the solubility of lithium salt in PFPE increases.

[0143] In the above-mentioned fluoropolyether group-containing compounds, RF The number average molecular weight of the part is not particularly limited, and 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 is 19 The value measured by F-NMR.

[0144] 1.2 LiI dissolved in PFPE

[0145] According to the inventors' understanding, PFPE itself does not have lithium ion conductivity, so when PFPE is mixed with battery materials, PFPE tends to become a battery resistor. In response to this problem, the inventors believe that PFPE can exhibit lithium ion conductivity by dissolving a lithium salt in PFPE.

[0146] As lithium salts that can be used as battery materials, for example, halides (LiF, LiCl, LiBr, LiI), imide salts (LiTFSI), etc. can be listed. According to the understanding of the present inventors, among various lithium salts, LiI is particularly easy to dissolve in the above-mentioned PFPE, and it is easy for PFPE to exhibit lithium ion conductivity. Compared with fluorine, chlorine and bromine, iodine has a lower electronegativity. That is, it is believed that LiI has the property of easily dissociating lithium ions compared with LiF, LiCl and LiBr, and therefore has high solubility in the above-mentioned PFPE.

[0147] The concentration of LiI in PFPE is not particularly limited and can be appropriately adjusted according to the target lithium ion conductivity. For example, the molar concentration of LiI in PFPE can 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 is below the saturation concentration.

[0148] 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 iodide ions in PFPE, but may exist in the form of some kind of association. In either case, PFPE can exhibit lithium ion conductivity by dissolving LiI in PFPE.

[0149] It should be noted that, in the present application, “LiI dissolved in PFPE” is not limited to a state in which LiI as a lithium salt is added to PFPE and dissolved, but also includes a state in which a Li source and an I source are separately added to PFPE and dissolved, resulting in LiI being dissolved in PFPE.

[0150] 1.3 Other ingredients

[0151] The lithium ion conductive material of the present invention may contain other additives in addition to the above-mentioned PFPE and LiI. As other additives, various additives may be used depending on the target performance.

[0152] 2. Secondary battery

[0153] The technology of the present invention also has an aspect as a secondary battery having the above-mentioned lithium ion conductive material. Figure 1 As shown, a secondary battery 100 according to one embodiment includes 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 lithium ion conductive material of the present invention.

[0154] 2.1 Positive Electrode

[0155] The structure of the positive electrode 10 is not particularly limited as long as it can properly function as the positive electrode of the secondary battery. Figure 1 As shown, the positive electrode 10 may include a positive electrode active material layer 11 and a positive electrode collector 12 .

[0156] 2.1.1 Positive electrode active material layer

[0157] The positive electrode active material layer 11 contains at least a positive electrode active material, and may optionally contain an electrolyte, a conductive aid, a binder, and the like. The positive electrode active material layer 11 may contain various additives in addition thereto. The content of each component in the positive electrode active material layer 11 can be appropriately determined according to the target battery performance. For example, the positive electrode active material layer 11 as a whole (solid component as a whole) is set to 100 mass%, and the content of the positive electrode active material can be 40 mass% or more, 50 mass% or more, 60 mass% or more, or 70 mass% or more, or 100 mass% or less or 90 mass% or less. The shape of the positive electrode active material layer 11 is not particularly limited, for example, it can be a sheet-shaped positive electrode active material layer having a roughly flat surface. The thickness of the positive electrode active material layer 11 is not particularly limited, for example, it can be 0.1 μm or more, 1 μm or more, or 10 μm or more, or it can be 2 mm or less, 1 mm or less, or 500 μm or less.

[0158] As the positive electrode active material, an active material known as a positive electrode active material for a secondary battery can be used. Among the known active materials, a material with a relatively high potential for absorbing and releasing lithium ions (charge and discharge potential) can be used as the positive electrode active material, and a material with a relatively low potential can be used as the negative electrode active material described later. The positive electrode active material can be, for example, at least one selected from various lithium-containing compounds, elemental sulfur, and sulfur compounds. The lithium-containing compound used as the positive electrode active material can be lithium cobalt oxide, lithium nickel oxide, Li 1±α Ni 1 / 3 Co 1 / 3 Mn1 / 3 O 2±δ , lithium manganate, spinel lithium compounds (composed of Li 1+ x Mn 2-x-y M y O4 (M is one or more selected from Al, Mg, Co, Fe, Ni and Zn) represented by heterogeneous element substitution Li-Mn spinel, etc.), lithium titanate, lithium metal phosphate (LiMPO4, etc., M is one or more selected from Fe, Mn, Co and Ni). In particular, in the case where the positive electrode active material includes a lithium-containing oxide containing at least one of Ni, Co and Mn, Li and O as constituent elements, a higher effect can be expected. The positive electrode active material can be used alone or in combination of two or more.

[0159] The shape of the positive electrode active material can be any shape generally used as a positive electrode active material for a battery. The positive electrode active material can be, for example, in a particle shape. The positive electrode active material can be hollow, can have voids, or can be porous. The positive electrode active material can be a primary particle, or a secondary particle obtained by agglomerating multiple primary particles. The average particle size D50 of the positive electrode active material can be, for example, greater than 1 nm, greater than 5 nm, or greater than 10 nm, and can also be less than 500 μm, less than 100 μm, less than 50 μm, or less than 30 μm. It should be noted that the average particle size D50 described in this application refers to the particle size (median particle size) when the cumulative value in the volume-based particle size distribution obtained by the laser diffraction / scattering method is 50%.

[0160] A protective layer containing an ion conductive oxide may be formed on the surface of the positive electrode active material. This makes it easy to suppress the reaction between the positive electrode active material and the sulfide (for example, the sulfide solid electrolyte described later). Examples of ion conductive oxides include: Li3BO3, LiBO2, Li2CO3, LiAlO2, Li4SiO4, Li2SiO3, Li3PO4, Li2SO4, Li2TiO3, Li4Ti5O 12 , Li2Ti2O5, Li2ZrO3, LiNbO3, Li2MoO4, Li2WO4, etc. The ion conductive oxide may also be a substance in which a part of the elements are replaced by doping elements such as P and B. The coverage rate (area rate) of the protective layer on 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 less, or 100 nm or less or 20 nm or less.

[0161] The electrolyte that can be included in the positive electrode active material layer 11 can be a solid electrolyte, a liquid electrolyte (electrolyte), or a combination thereof. In particular, when the positive electrode active material layer 11 contains at least a solid electrolyte as an electrolyte, a high effect is easily obtained. In addition, when the positive electrode active material layer 11 contains at least a solid electrolyte and the above-mentioned lithium ion conductive material of the present invention as an electrolyte, a higher effect is easily obtained.

[0162] The solid electrolyte can be a solid electrolyte known as a solid electrolyte for a secondary battery. The solid electrolyte can be an inorganic solid electrolyte or an organic polymer electrolyte. In particular, inorganic solid electrolytes have excellent ion conductivity and heat resistance. Examples of inorganic solid electrolytes include lithium lanthanum zirconate, LiPON, Li 1+ X Al X Ge 2-X (PO4)3, Li-SiO glass, Li-Al-SO glass and other oxide solid electrolytes; Li2S-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Si2S-P2S5, Li2S-P2S5-LiI-LiBr, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5-GeS2 and other sulfide solid electrolytes. 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, in a particle form. The solid electrolyte may be used alone or in combination of two or more.

[0163] The electrolyte may contain specified carrier ions (e.g., lithium ions). The electrolyte may be, for example, a non-aqueous electrolyte. The composition of the electrolyte may be the same as the composition known as the composition of the electrolyte of a secondary battery. For example, as the electrolyte, an electrolyte in which a lithium salt is dissolved in a carbonate solvent at a specified concentration may be used. Examples of carbonate solvents include: fluoroethylene carbonate (FEC), ethylene carbonate (EC), dimethyl carbonate (DMC), and the like. Examples of lithium salts include LiPF6, and the like.

[0164] As the conductive aid that can be included in the positive electrode active material layer 11, for example, carbon materials such as vapor grown carbon fiber (VGCF), acetylene black (AB), Ketjen black (KB), carbon nanotubes (CNT), and carbon nanofibers (CNF); metal materials such as nickel, aluminum, and stainless steel. The conductive aid can be, for example, in the form of particles or fibers, and its size is not particularly limited. The conductive aid can be used alone or in combination of two or more.

[0165] As the binder that can be included in the positive electrode active material layer 11, for example, there can be listed: butadiene rubber (BR) type binder, butylene rubber (IIR) type binder, acrylate butadiene rubber (ABR) type binder, styrene butadiene rubber (SBR) type binder, polyvinylidene fluoride (PVdF) type binder, polytetrafluoroethylene (PTFE) type binder, polyimide (PI) type binder, etc. The binder can be used alone or in combination of two or more.

[0166] 2.1.2 Positive electrode collector

[0167] like Figure 1 As shown, the positive electrode 10 may have a positive electrode collector 12 in contact with the above-mentioned positive electrode active material layer 11. The positive electrode collector 12 may be any of the collectors generally used as positive electrode collectors of batteries. In addition, the positive electrode collector 12 may be in the form of foil, plate, mesh, punched metal, foam, etc. The positive electrode collector 12 may be composed of a metal foil or a metal mesh. In particular, the metal foil has excellent operability. The positive electrode collector 12 may be composed of a plurality of foils. As metals constituting the positive electrode collector 12, there may be listed: Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, etc. In particular, from the viewpoint of ensuring oxidation resistance, etc., the positive electrode collector 12 may contain Al. The positive electrode collector 12 may have a coating on its surface for the purpose of adjusting resistance, etc. In addition, the positive electrode collector 12 may be plated or vapor-deposited with the above-mentioned metal on the metal foil or substrate. When the positive electrode current collector 12 is composed of a plurality of metal foils, some layers may be provided between the plurality of metal foils. 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 less, or 1 mm or less or 100 μm or less.

[0168] 2.2 Electrolyte layer

[0169] The electrolyte layer 20 is arranged 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 optionally contain a binder, etc. The electrolyte layer 20 may also contain various additives. The content of each component in the electrolyte layer 20 is not particularly limited, and can be appropriately determined according to the target battery performance. The shape of the electrolyte layer 20 is not particularly limited, for example, it can be a sheet with a roughly flat surface. The thickness of the electrolyte layer 20 is not particularly limited, for example, it can be 0.1μm or more or 1μm or less, or it can be 2mm or less or 1mm or less.

[0170] 2.2.1 Electrolyte

[0171] As the electrolyte contained in the electrolyte layer 20, it can be appropriately selected from the electrolytes exemplified as the electrolytes that can be contained in the above-mentioned positive electrode active material layer. In particular, the performance of the electrolyte layer 20 containing a solid electrolyte, especially a sulfide solid electrolyte, and further especially a sulfide solid electrolyte containing at least Li, S and P as constituent elements is high. In addition, when the electrolyte layer 20 contains at least a solid electrolyte and the lithium ion conductive material of the present invention as an electrolyte, it is easy to obtain a higher effect. In the case where the electrolyte is a solid electrolyte, the solid electrolyte can be amorphous or crystalline. In the case where the electrolyte is a solid electrolyte, the solid electrolyte can be, for example, in a particle form. The electrolyte can be used alone or in combination of two or more.

[0172] 2.2.2 Binder

[0173] The binder that can be contained in the electrolyte layer 20 can be appropriately selected from the binders exemplified as the binders that can be contained in the above-mentioned positive electrode active material layer.

[0174] 2.3 Negative electrode

[0175] The negative electrode 30 has no particular limitation on its structure as long as it can properly function as the negative electrode of the secondary battery. Figure 1 As shown, the negative electrode 30 may include a negative electrode active material layer 31 and a negative electrode collector 32 .

[0176] 2.3.1 Negative electrode active material layer

[0177] The negative electrode active material layer 31 contains at least a negative electrode active material, and may optionally contain an electrolyte, a conductive aid, a binder, etc. The negative electrode active material layer 31 may contain various additives in addition. The content of each component in the negative electrode active material layer 31 can be appropriately determined according to the target battery performance. For example, the entire negative electrode active material layer 31 (the entire solid component) is set to 100 mass%, and the content of the negative electrode active material can be 40 mass% or more, 50 mass% or more, 60 mass% or more, or 70 mass% or more, or it can be 100 mass% or less or 90 mass% or less. The shape of the negative electrode active material layer 31 is not particularly limited, for example, it can be a sheet-shaped negative electrode active material layer with a roughly flat surface. The thickness of the negative electrode active material layer 31 is not particularly limited, for example, it can be 0.1 μm or more, 1 μm or more, or 10 μm or more, or it can be 2 mm or less, 1 mm or less, or 500 μm or less.

[0178] As the negative electrode active material, various materials having a potential (charge and discharge potential) of absorbing and releasing lithium ions lower than that of the positive electrode active material can be used. For example, the negative electrode active material can 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. The negative electrode active material can be used alone or in combination of two or more.

[0179] The shape of the negative electrode active material can be any shape that is generally used as a negative electrode active material for a battery. The negative electrode active material can be, for example, in a particle shape. The negative electrode active material can be hollow, have voids, or be porous. The negative electrode active material can be a primary particle, or a secondary particle obtained by agglomerating multiple primary particles. The average particle size D50 of the negative electrode active material can be, for example, greater than 1 nm, greater than 5 nm, or greater than 10 nm, and can also be less than 500 μm, less than 100 μm, less than 50 μm, or less than 30 μm. Alternatively, the negative electrode active material can be in the form of a sheet (foil, film) such as lithium foil. That is, the negative electrode active material layer 31 can be composed of sheets of negative electrode active material.

[0180] The electrolyte that can be included in the negative electrode active material layer 31 can be a solid electrolyte, a liquid electrolyte (electrolyte), or a combination thereof. In particular, when the negative electrode active material layer 31 contains at least a solid electrolyte as an electrolyte, a high effect can be easily obtained. In addition, when the negative electrode active material layer 31 contains at least a solid electrolyte and the above-mentioned lithium ion conductive material of the present invention as an electrolyte, a higher effect can be easily obtained. The negative electrode active material layer 31 can contain a solid electrolyte, especially a sulfide solid electrolyte, and further especially a sulfide solid electrolyte containing Li2S-P2S5. As conductive aids that can be included in the negative electrode active material layer 31, the above-mentioned carbon materials, the above-mentioned metal materials, etc. can be listed. The binder that can be included in the negative electrode active material layer 31 can be appropriately selected from the binders exemplified as the binders that can be included in the above-mentioned positive electrode active material layer 11.

[0181] 2.3.2 Negative electrode collector

[0182] like Figure 1 As shown, the negative electrode 30 may have a negative electrode collector 32 in contact with the above-mentioned negative electrode active material layer 31. The negative electrode collector 32 may be any of the collectors generally used as negative electrode collectors of batteries. In addition, the negative electrode collector 32 may be in the form of foil, plate, mesh, punched metal, foam, etc. The negative electrode collector 32 may be a metal foil or a metal mesh, or may be a carbon sheet. In particular, the metal foil has excellent operability. The negative electrode collector 32 may be composed of a plurality of foils and sheets. As metals constituting the negative electrode collector 32, there may be listed: Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, etc. In particular, from the viewpoint of ensuring reduction resistance and the viewpoint of not being easily alloyed with lithium, the negative electrode collector 32 may contain at least one metal selected from Cu, Ni and stainless steel. The negative electrode collector 32 may have a coating on its surface for the purpose of adjusting resistance, etc. In addition, the negative electrode current collector 32 may be formed by plating or vapor-depositing the above metal on a metal foil or a substrate. In addition, when the negative electrode current collector 32 is composed of a plurality of metal foils, a certain layer may be provided between the plurality of metal foils. 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 less, or 1 mm or less or 100 μm or less.

[0183] 2.4 Lithium ion conductive materials

[0184] In the secondary battery 100, the lithium ion conductive material of the present invention 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 be filled in at least a part of the voids (gaps between solid materials) existing in the positive electrode 10, the electrolyte layer 20, and the negative electrode 30, for example. In addition, 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 part of the lithium ion conductive material of the present invention may be in contact with a part of the sulfide solid electrolyte. Here, in the secondary battery 100, PFPE having low reactivity with the sulfide solid electrolyte is used. Therefore, even if PFPE is in contact with the sulfide solid electrolyte, the sulfide solid electrolyte is not easily deteriorated and degraded, and the high ion conductivity of the sulfide solid electrolyte is easily maintained.

[0185] 2.5 Other components

[0186] In the secondary battery 100, each of the above-mentioned structures can be housed inside the outer casing. The outer casing can be any of the outer casings known as the outer casing of the battery. In addition, a plurality of secondary batteries 100 can be electrically connected arbitrarily, and can be arbitrarily overlapped to form a battery pack. In this case, the battery pack can be housed inside a known battery casing. The secondary battery 100 can have obvious structures such as necessary terminals in addition. As the shape of the secondary battery 100, for example, coin-shaped, laminated, cylindrical, and square shapes can be listed.

[0187] 2.6 Method for manufacturing secondary battery

[0188] 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 following method, and each layer can be formed by dry molding or the like, for example.

[0189] (1) A negative electrode active material constituting a negative electrode active material layer is 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. Then, the negative electrode slurry is coated on the surface of a negative electrode collector or an electrolyte layer described later using a doctor blade, and then dried to form a negative electrode active material layer on the surface of the negative electrode collector or the electrolyte layer to prepare a negative electrode. Here, the negative electrode active material layer can be pressed into shape.

[0190] (2) The positive electrode active material constituting the positive electrode active material layer is dispersed in a solvent to obtain a positive electrode slurry. The solvent used in this case is not particularly limited, and water or various organic solvents can be used. Then, the positive electrode slurry is coated on the surface of the positive electrode collector or the electrolyte layer described later using a doctor blade, and then dried to form a positive electrode active material layer on the surface of the positive electrode collector or the electrolyte layer to prepare a positive electrode. Here, the positive electrode active material layer can be pressed into shape.

[0191] (3) The layers are stacked in such a manner that the electrolyte layer is sandwiched between the negative electrode and the positive electrode to obtain a laminate having a negative electrode collector, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer and a positive electrode collector in sequence. The electrolyte layer can be, for example, an electrolyte layer obtained by molding an electrolyte mixture containing an electrolyte and a binder, or an electrolyte layer obtained by compression molding. Alternatively, in the case of manufacturing an electrolyte battery, a separator as an electrolyte layer can be sandwiched between the negative electrode active material layer and the positive electrode active material layer. Here, the laminate can be further compression molded. Other components such as terminals can be installed on the laminate as needed.

[0192] (4) A secondary battery is obtained by placing the laminate together with an optional electrolyte in a battery case and sealing the battery case. It should be noted that the timing of including the lithium ion conductive material of the present invention in 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 above (1) to (3), or when the laminate is placed in the battery case or thereafter.

[0193] Example

[0194] Hereinafter, the technology of the present invention will be described in further detail while showing examples, but the technology of the present invention is not limited to the following examples.

[0195] 1. Preparation of lithium ion conductive materials

[0196] The evaluation material is prepared by mixing PFPE (I) or (II) as a perfluoropolyether and at least one selected from lithium trifluoromethanesulfonyl imide (LiTFSI), lithium fluoride (LiF) and lithium iodide (LiI) as a lithium salt. The concentration of the lithium salt relative to PFPE is shown in Table 1 below. It should be noted that PFPE (I) is a liquid compound having a chemical structure represented by the following formula (I) (m / n is 1.2, the number average molecular weight is 5120, and the terminal R exists in an average ratio of 1:0.17 CF3 and CF2CF3), and PFPE (II) is a liquid compound having a chemical structure represented by the following formula (II) (m / n is 1.3, the number average molecular weight is 4238).

[0197]

[0198] 2. Determination of ionic conductivity

[0199] For each evaluation material, the lithium ion conductivity was confirmed by measuring the electrical resistance using an AC impedance method.

[0200] 3. Evaluation of reactivity to lithium

[0201] PFPE (I) or (II) is brought into contact with a metal lithium foil, and the presence or absence of color change is confirmed. If color change is confirmed, it can be said that PFPE reacts with lithium.

[0202] 4. Evaluation results

[0203] The evaluation results are shown in Table 1 below.

[0204] [Table 1]

[0205]

[0206] The results shown in Table 1 show the following.

[0207] (1) In Comparative Examples 1 to 4, since LiTFSI or LiF was used as the lithium salt, the lithium salt could not be appropriately dissolved in PFPE, and PFPE could not exhibit lithium ion conductivity.

[0208] (2) In Examples 1 to 4, since LiI is used as the lithium salt, LiI can be dissolved in PFPE (I) or (II). As a result, PFPE can exhibit lithium ion conductivity. In addition, no reaction between PFPE and lithium is confirmed, and PFPE is suitable as a lithium ion conductive material for secondary batteries, for example.

[0209] In addition, although PFPE having a specific chemical structure is exemplified in the above-mentioned embodiments, the chemical structure of PFPE is not limited thereto. In addition, the concentration of the lithium salt in the lithium ion conductive material is not limited to the above-mentioned specific concentration.

[0210] As described above, the material including a predetermined 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, a secondary battery.

[0211] Explanation of symbols

[0212] 10 Positive electrode

[0213] 11 Positive electrode active material layer

[0214] 12Positive electrode collector

[0215] 20 electrolyte layer

[0216] 30 negative electrode

[0217] 31 Negative electrode active material layer

[0218] 32 Negative electrode collector

[0219] 100 Secondary Batteries

Claims

1. A lithium ion conductive material comprising a perfluoropolyether represented by the following formula (1) and LiI dissolved in the perfluoropolyether, E1-Rf1-R F -O-Rf2-E2 (1) In formula (1), Rf1 and Rf2 are each independently a C1-16 divalent alkylene group which may be substituted with one or more fluorine atoms, E1 and E2 are each independently a monovalent group selected from the group consisting of a fluoro 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 It is a divalent fluoropolyether group.

2. The lithium ion conductive material according to claim 1, wherein The R F is a group represented by formula (2), -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3R Fa 6) d -(OC2F4) e -(OCF2) f - (2) In formula (2), each occurrence of R Fa are each independently a hydrogen atom, a fluorine atom or a chlorine atom, 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 greater than 1, The order of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula. Among them, in all R Fa When it is a hydrogen atom or a chlorine atom, at least one of a, b, c, e and f is 1 or more.

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

4. The lithium ion conductive material according to claim 3, wherein Each occurrence of R F are each independently a group represented by the following formula (2-1), (2-2), (2-3), (2-4) or (2-5), -(OC3F6) d -(OC2F4) e - (2-1) In formula (2-1), d is an integer of 1 to 200, e is 0 or 1, -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-2) In formula (2-2), c and d are each independently an integer of 0 to 30, e and f are each independently an integer of 1 to 200, The sum of c, d, e and f is an integer from 10 to 200, The order of the repeating units marked with the subscript c, d, e or f and enclosed in parentheses is arbitrary in the formula. -(R 6 -R 7 ) g - (2-3) In formula (2-3), R 6 For OCF2 or OC2F4, R 7 is selected from OC2F4, OC3F6, OC4F8, OC5F 10 and OC6F 12 or a combination of two or three groups selected from these groups, g is an integer from 2 to 100, -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-4) In formula (2-4), e is an integer of 1 to 200, a, b, c, d and f are each independently an integer of 0 to 200, The order of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses is arbitrary in the formula. -(OC6F 12 ) a -(OC5F 10 ) b -(OC4F8) c -(OC3F6) d -(OC2F4) e -(OCF2) f - (2-5) In formula (2-5), f is an integer greater than or equal to 1 and less than or equal to 200, a, b, c, d and e are each independently an integer of 0 to 200, The order of presence of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses in the formula is arbitrary.

5. The lithium ion conductive material according to claim 4, wherein The R F is a group represented by the following formula (2-6), -(OCF2CF2CF2) a -(OCF(CF3)CF2) b -(OCF2CF(CF3)) c -(OCF2CF2) d -(OCF(CF3)) e -(OCF2) f - (2-6) In formula (2-6), 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 greater than 1, The order of presence of the repeating units indicated by a, b, c, d, e or f and enclosed in parentheses in the formula is arbitrary.

6. The lithium ion conductive material according to claim 4, wherein The R F is a group represented by the following formula (2-7), -(OCF2CF2) d -(OCF(CF3)) e -(OCF2) f - (2-7) In formula (2-7), d, e and f are each independently an integer of 0 to 200, The sum of d, e and f is greater than 1, The order of presence of the repeating units indicated by d, e or f and enclosed in parentheses is arbitrary in the formula.

7. The lithium ion conductive material according to any one of claims 1 to 6, wherein The E1-Rf1 and the E2-Rf2 are each independently a group selected from the group consisting of -CF3, -CF2CF3 and -CF2CF2CF3. 8 . A secondary battery comprising 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 according to claim 1 .

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