Non-aqueous electrolyte, non-aqueous electrolyte energy storage element, and method for manufacturing a non-aqueous electrolyte energy storage element

Abstract

To provide: a nonaqueous electrolyte capable of suppressing corrosion of a positive electrode substrate as compared with a nonaqueous electrolyte for a nonaqueous electrolyte power storage element having the same imide salt content as that of the nonaqueous electrolyte; a nonaqueous electrolyte power storage element including such nonaqueous electrolyte; and a method of manufacturing a nonaqueous electrolyte power storage element.SOLUTION: A nonaqueous electrolyte according to one aspect of the present invention is a nonaqueous electrolyte for nonaqueous electrolyte power storage elements which contains an imide salt and a compound represented by the following formula (1). In formula (1), R1 is a C1-10 hydrocarbon group, a C1-10 alkoxy group, or a halogen atom, n is an integer of 0 or more and 6 or less, and if n is 2 or more, multiple R1s may be the same or different from each other.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a non-aqueous electrolyte, a non-aqueous electrolyte storage element, and a method for manufacturing a non-aqueous electrolyte storage element.

Background Art

[0002] Non-aqueous electrolyte secondary batteries typified by lithium ion non-aqueous electrolyte secondary batteries are widely used in electronic devices such as personal computers and communication terminals, and automobiles, etc. because of their high energy density. A non-aqueous electrolyte secondary battery generally includes an electrode body having a pair of electrodes electrically separated by a separator, and a non-aqueous electrolyte interposed between the electrodes, and is configured to charge and discharge by transferring charge-transporting ions between both electrodes. Further, as non-aqueous electrolyte storage elements other than non-aqueous electrolyte secondary batteries, capacitors such as lithium ion capacitors and electric double layer capacitors are also widely popular.

[0003] Generally, a non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent, and may further contain other components as necessary. As the electrolyte salts used in non-aqueous electrolyte storage elements, imide salts such as lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate (LiPF6), etc. are widely known (see Patent Documents 1 and 2). Further, as the base material of the positive electrode used in non-aqueous electrolyte storage elements, a foil made of metallic aluminum is widely used from the viewpoint of high conductivity, etc. (see Patent Document 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] When imide salts are used as electrolyte salts in non-aqueous electrolytes, the ionic conductivity of the non-aqueous electrolyte is increased compared to when LiPF6, etc. is used, resulting in advantages such as improved output of the non-aqueous electrolyte energy storage element. However, non-aqueous electrolyte energy storage elements equipped with non-aqueous electrolytes containing imide salts have the disadvantage of being more susceptible to corrosion of the positive electrode substrate (hereinafter, the positive electrode substrate is also referred to as the "positive electrode substrate") compared to non-aqueous electrolyte energy storage elements equipped with non-aqueous electrolytes containing LiPF6, etc. Corrosion of the positive electrode substrate is a factor that reduces the performance of the energy storage element, such as discharge capacity. Furthermore, the higher the imide salt content in the non-aqueous electrolyte, the more likely the positive electrode substrate is to corrode.

[0006] The object of the present invention is to provide a non-aqueous electrolyte that can suppress corrosion of the positive electrode substrate compared to non-aqueous electrolytes for non-aqueous electrolyte energy storage elements with the same imide salt content, as well as a non-aqueous electrolyte energy storage element equipped with such a non-aqueous electrolyte and a method for manufacturing a non-aqueous electrolyte energy storage element. [Means for solving the problem]

[0007] One aspect of the present invention relates to a non-aqueous electrolyte for a non-aqueous electrolyte energy storage element, which contains an imide salt and a compound represented by the following formula (1). [ka] In the above equation (1), R 1 R is a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. n is an integer between 0 and 6. If n is 2 or greater, multiple R 1 They may be the same or different.

[0008] A non-aqueous electrolyte energy storage element according to another aspect of the present invention comprises a positive electrode having a substrate containing metallic aluminum and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains an imide salt and at least one selected from the group consisting of a compound represented by the following formula (1) and a complex having the above compound as a ligand. [ka] In the above equation (1), R 1 R is a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. n is an integer between 0 and 6. If n is 2 or greater, multiple R 1 They may be the same or different.

[0009] A method for manufacturing a non-aqueous electrolyte energy storage element according to another aspect of the present invention comprises preparing a positive electrode having a substrate containing metallic aluminum, and preparing a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains an imide salt and a compound represented by the following formula (1). [ka] In the above equation (1), R 1 R is a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. n is an integer between 0 and 6. If n is 2 or greater, multiple R 1 They may be the same or different. [Effects of the Invention]

[0010] According to one aspect of the present invention, it is possible to provide a non-aqueous electrolyte that can suppress corrosion of the positive electrode substrate compared to non-aqueous electrolytes for non-aqueous electrolyte energy storage elements with the same imide salt content, as well as a non-aqueous electrolyte energy storage element equipped with such a non-aqueous electrolyte and a method for manufacturing a non-aqueous electrolyte energy storage element. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a perspective view showing one embodiment of a non-aqueous electrolyte energy storage element. [Figure 2] Figure 2 is a schematic diagram showing one embodiment of an energy storage device composed of multiple non-aqueous electrolyte energy storage elements. [Modes for carrying out the invention]

[0012] First, an overview of the non-aqueous electrolyte, non-aqueous electrolyte energy storage element, and method for manufacturing the non-aqueous electrolyte energy storage element disclosed herein will be described.

[0013] One aspect of the present invention relates to a non-aqueous electrolyte for a non-aqueous electrolyte energy storage element, which contains an imide salt and a compound represented by the following formula (1). [ka] In the above equation (1), R 1 R is a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. n is an integer between 0 and 6. If n is 2 or greater, multiple R 1 They may be the same or different.

[0014] The non-aqueous electrolyte in question can suppress corrosion of the positive electrode substrate compared to non-aqueous electrolytes for non-aqueous electrolyte energy storage elements with the same imide salt content. The reason for this is not entirely clear, but the following reasons are speculated. For example, in the case of a non-aqueous electrolyte energy storage element equipped with a non-aqueous electrolyte containing LiPF6 as the electrolyte salt, it is thought that a film of fluoride derived from LiPF6 (for example, AlF3 in the case of a positive electrode substrate containing metallic aluminum) is formed on the surface of the positive electrode substrate, protecting the surface of the positive electrode substrate and suppressing corrosion. In contrast, in the case of a non-aqueous electrolyte energy storage element equipped with a conventional non-aqueous electrolyte containing an imide salt as the electrolyte salt, a sufficient film of fluoride is not formed on the surface of the positive electrode substrate, making the positive electrode substrate more susceptible to corrosion, and causing metal ions to leach from the positive electrode substrate into the non-aqueous electrolyte. In a non-aqueous electrolyte energy storage element equipped with a non-aqueous electrolyte according to one aspect of the present invention, a compound represented by the above formula (1) and metal ions (for example, aluminum ions leached from a positive electrode substrate containing metallic aluminum) form a complex in the non-aqueous electrolyte. This complex is thought to be highly stable against the oxidation potential of the positive electrode, and it is presumed that the formation of a film of this complex on the surface of the positive electrode substrate suppresses corrosion of the positive electrode substrate.

[0015] The content of the above compound is 0.1 mol / dm 3 or more and 5 mol / dm 3 or less, which is preferable. In such a case, corrosion of the positive electrode substrate can be further suppressed by forming an appropriate amount of a film on the surface of the positive electrode substrate or the like. The content of the compound in this non-aqueous electrolyte is the content at 20°C and 1 atmospheric pressure.

[0016] The non-aqueous electrolyte storage element according to another aspect of the present invention includes a positive electrode having a substrate containing metal aluminum and a non-aqueous electrolyte. The non-aqueous electrolyte is a non-aqueous electrolyte storage element containing at least one selected from the group consisting of an imide salt, the compound represented by the above formula (1), and a complex having the above compound as a ligand.

[0017] According to this non-aqueous electrolyte storage element, corrosion of the substrate containing metal aluminum, which is the positive electrode substrate, is suppressed as compared with a non-aqueous electrolyte storage element having a non-aqueous electrolyte with an equal content of imide salt.

[0018] The manufacturing method of the non-aqueous electrolyte storage element according to another aspect of the present invention includes preparing a positive electrode having a substrate containing metal aluminum and preparing a non-aqueous electrolyte. The non-aqueous electrolyte is a manufacturing method of a non-aqueous electrolyte storage element containing an imide salt and the compound represented by the above formula (1).

[0019] According to the manufacturing method of this non-aqueous electrolyte storage element, a non-aqueous electrolyte storage element in which corrosion of the substrate containing metal aluminum, which is the positive electrode substrate, is suppressed can be manufactured as compared with a non-aqueous electrolyte storage element having a non-aqueous electrolyte with an equal content of imide salt.

[0020] The non-aqueous electrolyte, non-aqueous electrolyte storage element, power storage device, manufacturing method of the non-aqueous electrolyte storage element, and other embodiments according to an embodiment of the present invention will be described in detail. Note that the names of the respective constituent members (each constituent element) used in each embodiment may be different from the names of the respective constituent members (each constituent element) used in the background art.

[0021] <Non-aqueous electrolyte> A non-aqueous electrolyte according to one embodiment of the present invention is a non-aqueous electrolyte for a non-aqueous electrolyte energy storage element containing an imide salt and a compound represented by the above formula (1). This non-aqueous electrolyte is suitable for use in non-aqueous electrolyte energy storage elements, particularly in non-aqueous electrolyte secondary batteries such as lithium-ion secondary batteries. This non-aqueous electrolyte may also be a non-aqueous electrolyte solution. The non-aqueous electrolyte solution contains a non-aqueous solvent in which the imide salt and the compound represented by the above formula (1) are dissolved.

[0022] (Imido salt) Examples of imide salts include lithium imide salts, sodium imide salts, potassium imide salts, magnesium imide salts, and imide salts containing onium ions, but lithium imide salts are preferred.

[0023] Lithium imide salts include LiN(SO2F)2 (lithium bis(fluorosulfonyl)imide: LiFSI), LiN(CF3SO2)2 (lithium bis(trifluoromethanesulfonyl)imide: LiTFSI), LiN(C2F5SO2)2 (lithium bis(pentafluoroethanesulfonyl)imide: LiBETI), LiN(C4F9SO2)2 (lithium bis(nonafluorobutanesulfonyl)imide), CF3-SO2-N-SO2-N-SO2CF3Li, and FS. Examples of lithium sulfonylimide salts include O2-N-SO2-C4F9Li, CF3-SO2-N-SO2-C4F9Li, CF3-SO2-N-SO2-CF2-SO2-N-SO2-CF3Li2, CF3-SO2-N-SO2-CF2-SO3Li2, and CF3-SO2-N-SO2-CF2-SO2-C(-SO2CF3)2Li2; and lithium phosphonylimide salts such as LiN(POF2)2 (lithium bis(difluorophosphonyl)imide: LiDFPI). One or more lithium imide salts can be used.

[0024] The imide salt preferably has a fluorine atom, and more specifically, it preferably has a fluorosulfonyl group, a difluorophosphonyl group, a fluoroalkyl group, etc.

[0025] Furthermore, bis(fluorosulfonyl)imide salts, such as LiFSI, are preferred as imide salts. Bis(fluorosulfonyl)imide salts have a higher corrosion potential for metallic aluminum, which is commonly used as a material for positive electrode substrates, compared to, for example, bis(trifluoromethanesulfonyl)imide salts. Therefore, using bis(fluorosulfonyl)imide salts can further suppress corrosion of the positive electrode substrate. In particular, bis(fluorosulfonyl)imide salts can be suitably used in non-aqueous electrolyte energy storage elements in which the positive electrode substrate contains metallic aluminum.

[0026] The imide salt content in the non-aqueous electrolyte is 0.1 mol / dm³ at 20°C and 1 atm. 3 More than 2.5mol / dm 3 The following is preferred: 0.3 mol / dm 3 More than 2.0mol / dm 3 The following is more preferable: 0.5 mol / dm 3 More than 1.5mol / dm 3 The following may be even more preferable: 0.7 mol / dm 3 More than 1.2mol / dm 3 The following may be even more preferable: By setting the imide salt content within the above range, it is possible to increase the ionic conductivity of the non-aqueous electrolyte, etc.

[0027] (Other electrolyte salts, etc.) The non-aqueous electrolyte may or may not contain other electrolyte salts other than imide salts. Examples of other electrolyte salts include lithium salts such as LiPF6, LiPO2F2, LiBF4, LiClO4, lithium bis(oxalate) borate (LiBOB), lithium difluorooxalate borate (LiFOB), lithium bis(oxalate) difluorophosphate (LiFOP), and LiSO3CF3, with LiPF6 being preferred.

[0028] The lower limit of the imide salt content relative to the total electrolyte salts (imide salt and other electrolyte salts) in the non-aqueous electrolyte is preferably 20 mol%, more preferably 40 mol%, and even more preferably 60 mol%, 80 mol%, 90 mol%, or 99 mol%. By setting the imide salt content relative to the total electrolyte salts to above the above lower limit, the ionic conductivity of the non-aqueous electrolyte can be increased. On the other hand, the upper limit of the imide salt content relative to the total electrolyte salts may be 100 mol%, 99 mol%, 90 mol%, 80 mol%, 70 mol%, or 60 mol%. By setting the imide salt content relative to the total electrolyte salts to below the above upper limit, corrosion of the positive electrode substrate can be further suppressed. The imide salt content relative to the total electrolyte salts may be above any of the lower limits and below any of the upper limits.

[0029] The total electrolyte salt content in the non-aqueous electrolyte is 0.1 mol / dm³ at 20°C and 1 atm. 3 More than 2.5mol / dm 3 The following is preferred: 0.3 mol / dm 3 More than 2.0mol / dm 3 The following is more preferable: 0.5 mol / dm 3 More than 1.5mol / dm 3 The following is even more preferable: 0.7 mol / dm 3 More than 1.2mol / dm 3 The following is even more preferable: By setting the total electrolyte salt content within the above range, the ionic conductivity of the non-aqueous electrolyte can be increased.

[0030] (The compound represented by formula (1)) [ka]

[0031] In the above equation (1), R 1 R is a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. n is an integer between 0 and 6. If n is 2 or greater, multiple R 1 They may be the same or different.

[0032] R 1 The hydrocarbon group represented by may be either an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Examples of aliphatic hydrocarbon groups include linear hydrocarbon groups such as alkyl groups, alkenyl groups, and alkynyl groups, and alicyclic groups such as cycloalkyl groups. Examples of aromatic hydrocarbon groups include phenyl groups and naphthyl groups. 1 The number of carbon atoms in the hydrocarbon group represented by may be 1 to 6 or 1 to 3. Examples of hydrocarbon groups with 1 to 3 carbon atoms include the methyl group, ethyl group, n-propyl group, and isopropyl group.

[0033] R 1 Examples of alkoxy groups represented by include groups in which an oxygen atom is bonded to the hydrocarbon group described above. The alkoxy group is not limited to groups in which an oxygen atom is bonded to an alkyl group. The alkoxy group may also be called an oxyhydrocarbon group. 1 The number of carbon atoms in the alkoxy group represented by may be 1 to 6, or 1 to 3.

[0034] R 1 Examples of halogen atoms represented by this formula include fluorine atoms and chlorine atoms.

[0035] n is preferably 0 or greater and 2 or less, more preferably 0 or 1, and even more preferably 0.

[0036] A suitable example of the compound represented by the above formula (1) is one in which n is an integer between 0 and 2, and R 1 Examples include compounds in which the group has 1 to 3 carbon atoms, a hydrocarbon group, or a fluorine atom. Specific examples of such compounds include 8-quinolinol, 2-methyl-8-quinolinol, 5-methyl-8-quinolinol, 2,5-dimethyl-8-quinolinol, 5-fluoro-8-quinolinol, and 5,7-difluoro-8-quinolinol. The compounds represented by formula (1) above may be used individually or as a mixture of two or more.

[0037] The content of the compound represented by formula (1) in the non-aqueous electrolyte is 0.1 mol / dm³. 3 More than 5mol / dm 3 The following is preferred: 0.3 mol / dm 3 More than 4mol / dm 3 The following is more preferable: 0.5 mol / dm 3 More than 3mol / dm 3 The following is even more preferable: 1.0 mol / dm 3 More than 2.5mol / dm 3 The following may be even more preferable. Furthermore, the upper limit of this content is 2.0 mol / dm³ 3 It may also be 1.5 mol / dm 3 or 1.0 mol / dm 3 This may also be the case. When the content of the compound represented by formula (1) is within the above range, a suitable amount of coating is formed on the surface of the positive electrode substrate, thereby further suppressing corrosion of the positive electrode substrate. Note that the content of the compound represented by formula (1) is the content at 20°C and 1 atmosphere.

[0038] While not particularly limited, the ratio (B / A) of the content B of the compound represented by formula (1) to the content A of the imide salt in the non-aqueous electrolyte can be 0.1 or more in molar terms. From the viewpoint of suppressing corrosion of the positive electrode substrate, the ratio (B / A) of the content B of the compound represented by formula (1) to the content A of the imide salt is preferably 0.3 or more, more preferably 0.5 or more, and even more preferably 0.7 or more. In some embodiments, the content ratio (B / A) may be 1 or more (for example, 1.2 or more) or 1.5 or more (for example, 2 or more). Furthermore, the ratio (B / A) of the content B of the compound represented by formula (1) to the content A of the imide salt is appropriately 5 or less, preferably 4 or less, and more preferably 3 or less (for example, 2.5 or less).

[0039] (Non-aqueous solvent) As the non-aqueous solvent, it can be appropriately selected from known non-aqueous solvents. Examples of non-aqueous solvents include cyclic carbonates, linear carbonates, carboxylic acid esters, phosphate esters, sulfonic acid esters, ethers, amides, and nitriles. As the non-aqueous solvent, compounds in which some of the hydrogen atoms contained in these compounds are substituted with halogens may also be used.

[0040] Examples of cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinylethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), styrene carbonate, 1-phenylvinylene carbonate, and 1,2-diphenylvinylene carbonate. Among these, EC and PC are preferred.

[0041] Examples of linear carbonates include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diphenyl carbonate, trifluoroethyl methyl carbonate, and bis(trifluoroethyl) carbonate. Among these, EMC is preferred.

[0042] It is preferable to use a cyclic carbonate or a linear carbonate as the non-aqueous solvent, and it is more preferable to use a cyclic carbonate and a linear carbonate in combination. Using a cyclic carbonate can promote the dissociation of the electrolyte salt and improve the ionic conductivity of the non-aqueous electrolyte. Using a linear carbonate can keep the viscosity of the non-aqueous electrolyte low. When using a cyclic carbonate and a linear carbonate in combination, the volume ratio of the cyclic carbonate to the linear carbonate (cyclic carbonate:linear carbonate) is preferably in the range of 5:95 to 50:50.

[0043] The non-aqueous electrolyte may contain other additives in addition to imide salts and other electrolyte salts, the compound represented by formula (1) above, and a non-aqueous solvent. Other additives include, for example, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; partially halides of the aforementioned aromatic compounds such as 2-fluorobiphenyl, o-cyclohexylfluorobenzene, and p-cyclohexylfluorobenzene; halogenated anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole; vinylene carbonate, methylvinylene carbonate, ethylvinylene carbonate, succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, cyclohexanedicarboxylic acid anhydride; ethylene sulfite, propylene sulfite, and Examples include dimethyl sulfate, methyl methanesulfonate, busulfan, methyl toluenesulfonate, dimethyl sulfate, ethylene sulfate, sulfolane, dimethyl sulfone, diethylsulfone, dimethyl sulfoxide, diethylsulfoxide, tetramethylene sulfoxide, diphenyl sulfide, 4,4'-bis(2,2-dioxo-1,3,2-dioxathiolane), 4-methylsulfonyloxymethyl-2,2-dioxo-1,3,2-dioxathiolane, thioanisole, diphenyl disulfide, dipyridinium disulfide, 1,3-propensultone, 1,3-propanesultone, 1,4-butanesultone, 1,4-butensultone, perfluorooctane, tristrimethylsilyl borate, tristrimethylsilyl phosphate, tetrakithtrimethylsilyl titanate, lithium monofluorophosphate, and lithium difluorophosphate. These other additives may be used individually or in combination of two or more.

[0044] The content of other additives in the non-aqueous electrolyte is preferably 0.01% to 10% by mass, more preferably 0.1% to 7% by mass, even more preferably 0.2% to 5% by mass, and particularly preferably 0.3% to 3% by mass, relative to the total mass of the non-aqueous electrolyte. By setting the content of other additives within the above range, it is possible to improve the capacity retention performance or cycle performance after high-temperature storage, or to further improve safety.

[0045] <Non-aqueous electrolyte energy storage element> A non-aqueous electrolyte energy storage element (hereinafter also simply referred to as "energy storage element") according to one embodiment of the present invention comprises an electrode body having a positive electrode, a negative electrode, and a separator, a non-aqueous electrolyte, and a container for housing the electrode body and the non-aqueous electrolyte. The electrode body is usually a stacked type in which a plurality of positive electrodes and a plurality of negative electrodes are stacked with a separator in between, or a wound type in which the positive electrode and negative electrode are wound in a stacked state with a separator in between. The non-aqueous electrolyte exists contained within the positive electrode, negative electrode, and separator. As an example of a non-aqueous electrolyte energy storage element, a non-aqueous electrolyte secondary battery (hereinafter also simply referred to as "secondary battery") will be described.

[0046] (positive electrode) The positive electrode comprises a positive electrode substrate and a positive electrode active material layer disposed directly on the positive electrode substrate or via an intermediate layer.

[0047] The positive electrode substrate is conductive. Whether or not it is conductive is determined by the volume resistivity measured in accordance with JIS-H-0505 (1975), which is 10 7The determination is made using Ω·cm as the threshold. The positive electrode substrate contains metallic aluminum. That is, aluminum or an aluminum alloy is used as the material for the positive electrode substrate. Compared to non-aqueous electrolyte energy storage elements with the same imide salt content, this non-aqueous electrolyte energy storage element exhibits suppressed corrosion of the substrate containing metallic aluminum, which is the positive electrode substrate. For this reason, a positive electrode substrate containing metallic aluminum is preferably used in this non-aqueous electrolyte energy storage element. Furthermore, a positive electrode substrate containing metallic aluminum has excellent potential resistance and conductivity, and is also preferable from a cost standpoint. Examples of positive electrode substrates include foil, vapor-deposited film, mesh, porous material, etc., with foil being preferred from a cost standpoint. Therefore, aluminum foil or aluminum alloy foil is preferred as the positive electrode substrate. Examples of aluminum or aluminum alloys include A1085, A3003, A1N30, etc., as specified in JIS-H-4000 (2014) or JIS-H-4160 (2006). The positive electrode substrate may have a coating layer of carbon material or the like on its surface. In one preferred embodiment, the positive electrode substrate has a coating on its surface. Such a coating may contain a complex in which a compound represented by formula (1) is coordinated to an aluminum ion.

[0048] The average thickness of the positive electrode substrate is preferably 3 μm to 50 μm, more preferably 5 μm to 40 μm, even more preferably 8 μm to 30 μm, and particularly preferably 10 μm to 25 μm. By setting the average thickness of the positive electrode substrate within the above range, it is possible to increase the strength of the positive electrode substrate while increasing the energy density per unit volume of the secondary battery.

[0049] The intermediate layer is a layer placed between the positive electrode substrate and the positive electrode active material layer. The intermediate layer contains a conductive agent such as carbon particles to reduce the contact resistance between the positive electrode substrate and the positive electrode active material layer. The composition of the intermediate layer is not particularly limited and may include, for example, a binder and a conductive agent.

[0050] The positive electrode active material layer contains a positive electrode active material. The positive electrode active material layer may optionally contain conductive agents, binders, thickeners, fillers, and other optional components.

[0051] The positive electrode active material can be appropriately selected from known positive electrode active materials. For lithium-ion secondary batteries, materials capable of intercalating and releasing lithium ions are typically used as positive electrode active materials. Examples of positive electrode active materials include lithium transition metal composite oxides having an α-NaFeO2 crystal structure, lithium transition metal composite oxides having a spinel crystal structure, polyanionic compounds, chalcogen compounds, and sulfur. Examples of lithium transition metal composite oxides having an α-NaFeO2 crystal structure include Li[Li x Ni (1-x) ]O2(0≦x<0.5), Li[Li x Ni γ Co (1-x-γ) ]O2(0≦x<0.5, 0<γ<1, 0<1-x-γ), Li[Li x Co (1-x) ]O2(0≦x<0.5), Li[Li x Ni γ Mn (1-x-γ) ]O2(0≦x<0.5, 0<γ<1, 0<1-x-γ), Li[Li x Ni γ Mn β Co (1-x-γ-β) ]O2(0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1, 0<1-x-γ-β), Li[Li x Ni γ Co β Al (1-x-γ-β) Examples include ]O2 (0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1, 0<1-x-γ-β), etc. As a lithium transition metal composite oxide having a spinel-type crystal structure, Li x Mn2O4, Li x Ni γ Mn (2-γ)Examples include O4. Examples of polyanion compounds include LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, Li3V2(PO4)3, Li2MnSiO4, Li2CoPO4F, etc. Examples of chalcogen compounds include titanium disulfide, molybdenum disulfide, molybdenum dioxide, etc. Some atoms or polyanions in these materials may be substituted with atoms or anions of other elements. The surfaces of these materials may be coated with other materials. In the positive electrode active material layer, one of these materials may be used alone, or two or more may be used in mixture form.

[0052] In one embodiment of the present invention, a non-aqueous electrolyte energy storage element has a higher corrosion initiation potential for the positive electrode substrate (a substrate containing metallic aluminum) and suppresses corrosion of the positive electrode substrate compared to a non-aqueous electrolyte energy storage element having the same imide salt content. For this reason, positive electrode active materials with a high charge-discharge reaction potential are also suitably used in this non-aqueous electrolyte energy storage element. Examples of positive electrode active materials with a high charge-discharge reaction potential include lithium transition metal composite oxides having an α-NaFeO2 type crystal structure and lithium transition metal composite oxides having a spinel type crystal structure. As lithium transition metal composite oxides having an α-NaFeO2 type crystal structure, lithium transition metal composite oxides containing one or more, preferably three, elements from nickel, manganese, and cobalt are preferred. As lithium transition metal composite oxides having a spinel type crystal structure, lithium transition metal composite oxides in which a portion of the transition metal elements are substituted with other transition metal elements are preferred, and lithium transition metal composite oxides containing manganese are also preferred. By using such positive electrode active materials, it is possible to increase the energy density of the non-aqueous electrolyte energy storage element.

[0053] The positive electrode active material is usually in the form of particles (powder). The average particle size of the positive electrode active material is preferably, for example, 0.1 μm or more and 20 μm or less. Setting the average particle size of the positive electrode active material above the lower limit makes it easier to manufacture or handle the positive electrode active material. Setting the average particle size of the positive electrode active material below the upper limit improves the electronic conductivity of the positive electrode active material layer. When a composite material of the positive electrode active material and other materials is used, the average particle size of the composite material is used as the average particle size of the positive electrode active material. "Average particle size" refers to the value at which the volume-based integrated distribution calculated in accordance with JIS-Z-8819-2 (2001), based on the particle size distribution measured by laser diffraction / scattering method on a dilution of particles diluted with a solvent, in accordance with JIS-Z-8825 (2013), becomes 50%.

[0054] To obtain powder with a predetermined particle size, grinders and classifiers are used. Examples of grinding methods include using mortars, ball mills, sand mills, vibrating ball mills, planetary ball mills, jet mills, counter-jet mills, swirling airflow jet mills, or sieves. Wet grinding, which involves the coexistence of water or organic solvents such as hexane, can also be used during grinding. For classification, sieves and wind classifiers are used as needed, both dry and wet.

[0055] The content of the positive electrode active material in the positive electrode active material layer is preferably 50% to 99% by mass, more preferably 70% to 98% by mass, and even more preferably 80% to 95% by mass. By setting the content of the positive electrode active material within the above range, it is possible to achieve both high energy density and manufacturability in the positive electrode active material layer.

[0056] The conductive agent is not particularly limited as long as it is a conductive material. Examples of such conductive agents include carbonaceous materials, metals, and conductive ceramics. Examples of carbonaceous materials include graphite, non-graphitic carbon, and graphene-based carbon. Examples of non-graphitic carbon include carbon nanofibers, pitch-based carbon fibers, and carbon black. Examples of carbon black include furnace black, acetylene black, and Ketjen black. Examples of graphene-based carbon include graphene, carbon nanotubes (CNTs), and fullerenes. The conductive agent can take the form of powder or fiber. One of these materials may be used alone as the conductive agent, or two or more may be used in mixture form. These materials may also be used in composite form. For example, a composite material of carbon black and CNTs may be used. Among these, carbon black is preferred from the viewpoint of electronic conductivity and coating properties, and acetylene black is particularly preferred.

[0057] The content of the conductive agent in the positive electrode active material layer is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 9% by mass or less. By setting the content of the conductive agent within the above range, the energy density of the secondary battery can be increased.

[0058] Examples of binders include thermoplastic resins such as fluororesins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), polyethylene, polypropylene, polyacrylic, and polyimide; elastomers such as ethylene-propylene-diene rubber (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), and fluororubber; and polysaccharide polymers.

[0059] The binder content in the positive electrode active material layer is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 9% by mass or less. By keeping the binder content within the above range, the active material can be stably retained.

[0060] Examples of thickening agents include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose. If the thickening agent has a functional group that reacts with lithium or the like, this functional group may be deactivated beforehand by methylation or the like.

[0061] The filler is not particularly limited. Examples of fillers include polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, alumina, titanium dioxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, and aluminosilicates, hydroxides such as magnesium hydroxide, calcium hydroxide, and aluminum hydroxide, carbonates such as calcium carbonate, sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium sulfate, nitrides such as aluminum nitride and silicon nitride, mineral resource-derived materials such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof.

[0062] The positive electrode active material layer may contain typical nonmetallic elements such as B, N, P, F, Cl, Br, and I, typical metallic elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, and Ba, and transition metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Nb, and W as components other than the positive electrode active material, conductive agent, binder, thickener, and filler.

[0063] (Negative electrode) The negative electrode comprises a negative electrode substrate and a negative electrode active material layer disposed directly on the negative electrode substrate or via an intermediate layer. The configuration of the intermediate layer is not particularly limited and can be selected from, for example, the configurations exemplified in the positive electrode.

[0064] The negative electrode substrate is electrically conductive. Suitable materials for the negative electrode substrate include metals such as copper, nickel, stainless steel, nickel-plated steel, and aluminum, or alloys thereof, as well as carbonaceous materials. Among these, copper or copper alloys are preferred. Examples of negative electrode substrates include foil, vapor-deposited film, mesh, and porous materials, with foil being preferred from a cost perspective. Therefore, copper foil or copper alloy foil is preferred as the negative electrode substrate. Examples of copper foil include rolled copper foil and electrolytic copper foil.

[0065] The average thickness of the negative electrode substrate is preferably 2 μm to 35 μm, more preferably 3 μm to 30 μm, even more preferably 4 μm to 25 μm, and particularly preferably 5 μm to 20 μm. By setting the average thickness of the negative electrode substrate within the above range, it is possible to increase the strength of the negative electrode substrate while increasing the energy density per unit volume of the secondary battery.

[0066] The negative electrode active material layer contains a negative electrode active material. The negative electrode active material layer optionally contains conductive agents, binders, thickeners, fillers, and other optional components. These optional components can be selected from the materials exemplified above for the positive electrode.

[0067] The negative electrode active material layer may contain typical nonmetallic elements such as B, N, P, F, Cl, Br, and I, typical metallic elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, and Ba, and transition metallic elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ta, Hf, Nb, and W as components other than the negative electrode active material, conductive agent, binder, thickener, and filler.

[0068] The negative electrode active material can be appropriately selected from known negative electrode active materials. For lithium-ion secondary batteries, materials capable of intercalating and releasing lithium ions are typically used as negative electrode active materials. Examples of negative electrode active materials include: metallic Li; metals or metalloids such as Si and Sn; metal oxides or metalloid oxides such as Si oxide, Ti oxide, and Sn oxide; and Li4Ti5O 12 LiTiO 2、Examples of materials include titanium-containing oxides such as TiNb2O7; polyphosphate compounds; silicon carbide; and carbon materials such as graphite and non-graphitizable carbon (easily graphitizable carbon or poorly graphitizable carbon). Among these materials, graphite and non-graphitizable carbon are preferred. In the negative electrode active material layer, one of these materials may be used alone, or two or more may be used in mixture form.

[0069] "Graphite" refers to the average lattice plane spacing (d) of the (002) plane, determined by X-ray diffraction before charging or discharging, or during the discharge state. 002 ) refers to carbon materials with a n-scale between 0.33 nm and less than 0.34 nm. Examples of graphite include natural graphite and artificial graphite. Artificial graphite is preferred from the standpoint of obtaining materials with stable physical properties.

[0070] "Non-graphite carbon" refers to the average lattice plane spacing (d) of the (002) plane, which is determined by X-ray diffraction before charging or during the discharge state. 002 This refers to carbon materials with a nautical radius of 0.34 nm or more and 0.42 nm or less. Non-graphitized carbons include poorly graphitizable carbons and easily graphitizable carbons. Examples of non-graphitized carbons include resin-derived materials, petroleum pitch or materials derived from petroleum pitch, petroleum coke or materials derived from petroleum coke, plant-derived materials, and alcohol-derived materials.

[0071] Here, "discharge state" refers to a state in which sufficient lithium ions that can be absorbed and released during charging and discharging are released from the carbon material, which is the negative electrode active material. For example, in a half-cell using a negative electrode containing a carbon material as the negative electrode active material as the working electrode and metallic Li as the counter electrode, this is the state in which the open-circuit voltage is 0.7V or higher.

[0072] "Non-graphitizable carbon" refers to the above d 002 This refers to carbon materials with a wavelength between 0.36 nm and 0.42 nm.

[0073] "Easily graphitizable carbon" refers to the above d 002 This refers to carbon materials with a wavelength of 0.34 nm or more and less than 0.36 nm.

[0074] The negative electrode active material is usually in the form of particles (powder). The average particle size of the negative electrode active material can be, for example, between 1 nm and 100 μm. If the negative electrode active material is a carbon material, titanium-containing oxide, or polyphosphate compound, its average particle size may be between 1 μm and 100 μm. If the negative electrode active material is Si, Sn, Si oxide, or Sn oxide, its average particle size may be between 1 nm and 1 μm. Setting the average particle size of the negative electrode active material above the lower limit makes it easier to manufacture or handle. Setting the average particle size of the negative electrode active material below the upper limit improves the electronic conductivity of the negative electrode active material layer. To obtain powder with a predetermined particle size, a pulverizer or classifier is used. The pulverizing method and classification method can be selected from, for example, the methods exemplified above for the positive electrode. If the negative electrode active material is a metal such as metallic Li, the negative electrode active material layer may be in the form of foil.

[0075] The content of the negative electrode active material in the negative electrode active material layer is preferably 60% by mass or more and 99% by mass or less, and more preferably 90% by mass or more and 98% by mass or less. By setting the content of the negative electrode active material within the above range, it is possible to achieve both high energy density and manufacturability in the negative electrode active material layer.

[0076] (Separator) The separator can be appropriately selected from known separators. Examples of separators include a separator consisting only of a base layer, or a separator in which a heat-resistant layer containing heat-resistant particles and a binder is formed on one or both sides of the base layer. Examples of the base layer shape of the separator include woven fabric, nonwoven fabric, and porous resin film. Among these shapes, porous resin film is preferred from the viewpoint of strength, and nonwoven fabric is preferred from the viewpoint of liquid retention of non-aqueous electrolytes. As for the material of the base layer of the separator, polyolefins such as polyethylene and polypropylene are preferred from the viewpoint of shutdown function, and polyimide and aramid are preferred from the viewpoint of oxidative degradation resistance. A composite material of these resins may also be used as the base layer of the separator.

[0077] The heat-resistant particles contained in the heat-resistant layer preferably have a mass loss of 5% or less when heated from room temperature to 500°C in an air atmosphere of 1 atmosphere, and more preferably have a mass loss of 5% or less when heated from room temperature to 800°C. Inorganic compounds are examples of materials with a mass loss of less than the specified amount. Examples of inorganic compounds include oxides such as iron oxide, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, and aluminosilicates; nitrides such as aluminum nitride and silicon nitride; carbonates such as calcium carbonate; sulfates such as barium sulfate; sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium titanate; covalent crystals such as silicon and diamond; mineral resource-derived materials such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof. These inorganic compounds may be used individually or in combination, or two or more may be used as a mixture. Among these inorganic compounds, silicon dioxide, aluminum oxide, or aluminosilicates are preferred from the viewpoint of safety for non-aqueous electrolyte energy storage elements.

[0078] The porosity of the separator is preferably 80 volume% or less from the viewpoint of strength, and preferably 20 volume% or more from the viewpoint of discharge performance. Here, "porosity" refers to a volume-based value and means the measurement value obtained using a mercury porosimeter.

[0079] A polymer gel composed of a polymer and a non-aqueous electrolyte may be used as a separator. Examples of polymers include polyacrylonitrile, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, and polyvinylidene fluoride. Using a polymer gel has the effect of suppressing leakage. A polymer gel may also be used in combination with a porous resin film or nonwoven fabric as described above as a separator.

[0080] (Non-aqueous electrolytes) The non-aqueous electrolyte in the non-aqueous electrolyte energy storage element contains an imide salt and at least one selected from the group consisting of the compound represented by formula (1) and complexes using the compound as a ligand. The non-aqueous electrolyte may also be a non-aqueous electrolyte solution. The non-aqueous electrolyte solution contains a non-aqueous solvent, in which the imide salt and at least one selected from the group consisting of the compound represented by formula (1) and complexes using the compound as a ligand are dissolved.

[0081] The specific forms and preferred forms of the imide salt and other electrolyte salts, non-aqueous solvent, and other additives contained in the non-aqueous electrolyte energy storage element are the same as those of the components in the non-aqueous electrolyte according to the above-described embodiment.

[0082] The non-aqueous electrolyte in the non-aqueous electrolyte energy storage element contains at least one selected from the group consisting of the compound represented by formula (1) and complexes having the compound as a ligand. The specific form and preferred form of the compound represented by formula (1) are the same as those of the compound represented by formula (1) in the non-aqueous electrolyte according to the embodiment of the present invention described above. The non-aqueous electrolyte in the non-aqueous electrolyte energy storage element may contain a complex having the compound represented by formula (1) as a ligand, either together with the compound represented by formula (1) or in place of the compound represented by formula (1). Normally, when charging and discharging is performed in the non-aqueous electrolyte energy storage element, aluminum ions dissolve from the positive electrode substrate, and a complex having the compound represented by formula (1) as a ligand is formed. That is, the complex having the compound represented by formula (1) as a ligand may be a complex in which the compound represented by formula (1) is coordinated to aluminum ions. It is presumed that such a complex will become a component that forms a film on the positive electrode substrate and can suppress corrosion of the positive electrode substrate. The above complex may have another ligand coordinated to the compound represented by formula (1). Furthermore, the complex with the compound represented by formula (1) as a ligand may be other complexes (for example, a complex in which the compound represented by formula (1) is coordinated to a lithium ion).

[0083] The content of the compound represented by the above formula (1) (including the ligand when forming a complex as a ligand) in the non-aqueous electrolyte provided in the non-aqueous electrolyte storage element is 0.1 mol / dm 3 or more and 5 mol / dm 3 or less is preferable, 0.3 mol / dm 3 or more and 4 mol / dm 3 or less is more preferable, 0.5 mol / dm 3 or more and 3 mol / dm 3 or less is even more preferable, 1.0 mol / dm 3 or more and 2.5 mol / dm 3 or less may be even more preferable in some cases. Further, the upper limit of this content may be 2.0 mol / dm 3 or 1.5 mol / dm 3 or 1.0 mol / dm 3 or less.

[0084] <00…>(Positive electrode potential at the end-of-charge voltage during normal use) In the non-aqueous electrolyte storage element, the positive electrode potential (positive electrode reaching potential) at the end-of-charge voltage during normal use is not particularly limited, but is 3.5 V vs. Li / Li + or more and 5.0 V vs. Li / Li + or less is preferable, 4.0 V vs. Li / Li + or more and 4.8 V vs. Li / Li + or less is more preferable, 4.2 V vs. Li / Li + or more and 4.6 V vs. Li / Li + or less is even more preferable, 4.4 V vs. Li / Li + or more may be even more preferable in some cases. When the positive electrode potential at the end-of-charge voltage during normal use is within the above range, corrosion of the positive electrode substrate can be suppressed while increasing the energy density and the like. Particularly in the non-aqueous electrolyte storage element, since corrosion of the positive electrode substrate is suppressed, even if the positive electrode potential (positive electrode reaching potential) at the end-of-charge voltage during normal use is set relatively high, corrosion of the positive electrode substrate is suppressed and a good charge / discharge function can be exhibited.

[0085] Here, "normal use" refers to using the non-aqueous electrolyte energy storage element under the recommended or specified charge and discharge conditions for that element, and, if a charger for the non-aqueous electrolyte energy storage element is available, using that charger.

[0086] The shape of the non-aqueous electrolyte energy storage element in this embodiment is not particularly limited, and examples include cylindrical batteries, prismatic batteries, flat batteries, coin-type batteries, button-type batteries, and the like.

[0087] Figure 1 shows a non-aqueous electrolyte energy storage element 1 as an example of a rectangular battery. Note that the figure is a transparent view of the inside of the container. An electrode body 2 having a positive electrode and a negative electrode wound around a separator is housed in a rectangular container 3. The positive electrode is electrically connected to the positive electrode terminal 4 via a positive electrode lead 41. The negative electrode is electrically connected to the negative electrode terminal 5 via a negative electrode lead 51.

[0088] <Energy storage device> The non-aqueous electrolyte energy storage element of this embodiment can be mounted as an energy storage unit (battery module) composed of multiple non-aqueous electrolyte energy storage elements 1 in power supplies for automobiles such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), power supplies for electronic devices such as personal computers and communication terminals, or power storage power supplies. In this case, it is sufficient that the technology of the present invention is applied to at least one of the non-aqueous electrolyte energy storage elements included in the energy storage unit.

[0089] Figure 2 shows an example of an energy storage device 30 which is formed by further assembling energy storage units 20, each of which is an assembly of two or more electrically connected non-aqueous electrolyte energy storage elements 1. The energy storage device 30 may include busbars (not shown) that electrically connect two or more non-aqueous electrolyte energy storage elements 1, busbars (not shown) that electrically connect two or more energy storage units 20, etc. The energy storage unit 20 or the energy storage device 30 may include a condition monitoring device (not shown) that monitors the state of one or more non-aqueous electrolyte energy storage elements.

[0090] <Method for manufacturing a non-aqueous electrolyte energy storage element> A method for manufacturing a non-aqueous electrolyte energy storage element according to one embodiment of the present invention comprises preparing a positive electrode, preparing a negative electrode, and preparing a non-aqueous electrolyte.

[0091] In preparing the positive electrode, a positive electrode having a substrate (positive electrode substrate) containing metallic aluminum is prepared. Preparing the positive electrode may also mean manufacturing the positive electrode. Manufacturing the positive electrode can be done, for example, by applying a positive electrode mixture paste directly to the positive electrode substrate or via an intermediate layer and drying it. The positive electrode mixture paste contains a positive electrode active material and optional components such as a conductive agent and a binder, which constitute the positive electrode mixture (positive electrode active material layer). The positive electrode mixture paste may further contain a dispersion medium. The specific form and preferred form of the prepared positive electrode are the same as the positive electrode provided in the non-aqueous electrolyte energy storage element according to the above-described embodiment of the present invention.

[0092] Preparing a negative electrode may also mean fabricating a negative electrode. A negative electrode can be fabricated, for example, by applying a negative electrode mixture paste directly to a negative electrode substrate or via an intermediate layer, and then drying it. The negative electrode mixture paste contains a negative electrode active material and optional components such as a conductive agent and a binder, which constitute the negative electrode mixture (negative electrode active material layer). The negative electrode mixture paste may further contain a dispersion medium. The specific and preferred forms of the prepared negative electrode are similar to those of the negative electrode provided in the non-aqueous electrolyte energy storage element according to the above-described embodiment of the present invention.

[0093] In preparing a non-aqueous electrolyte, a non-aqueous electrolyte containing an imide salt and a compound represented by formula (1) above is prepared. Preparing a non-aqueous electrolyte may also be equivalent to preparing a non-aqueous electrolyte. The preparation of a non-aqueous electrolyte can be carried out, for example, by mixing the components such as an imide salt, a compound represented by formula (1) above, and a non-aqueous solvent. Specific examples and preferred examples of the prepared non-aqueous electrolyte are the same as those for the non-aqueous electrolyte according to the embodiment of the present invention described above.

[0094] The method for manufacturing the non-aqueous electrolyte energy storage element may include forming an electrode body in which positive and negative electrodes are alternately superimposed by stacking or winding them with a separator in between, housing the positive and negative electrodes (electrode body) in a container, and injecting a non-aqueous electrolyte into the container. After injection, the non-aqueous electrolyte energy storage element can be obtained by sealing the injection port.

[0095] <Other Embodiments> Furthermore, the non-aqueous electrolyte energy storage element of the present invention is not limited to the above embodiments, and various modifications may be made without departing from the spirit of the present invention. For example, the configuration of one embodiment may be added to the configuration of another embodiment, and a part of the configuration of one embodiment may be replaced with the configuration of another embodiment or known technology. In addition, a part of the configuration of one embodiment may be deleted. Also, known technology may be added to the configuration of one embodiment.

[0096] In the above embodiment, the case in which the non-aqueous electrolyte energy storage element is used as a rechargeable non-aqueous electrolyte secondary battery (e.g., a lithium-ion secondary battery) was described, but the type, shape, dimensions, capacity, etc. of the non-aqueous electrolyte energy storage element are arbitrary. The present invention can also be applied to various secondary batteries, electric double-layer capacitors, or capacitors such as lithium-ion capacitors.

[0097] In the above embodiment, an electrode body in which a positive electrode and a negative electrode are stacked with a separator in between has been described, but the electrode body does not need to have a separator. For example, the positive electrode and the negative electrode may be in direct contact with each other, with a non-conductive layer formed on the active material layer of either the positive electrode or the negative electrode.

[0098] Furthermore, the non-aqueous electrolyte of the present invention can also be used in non-aqueous electrolyte energy storage elements that have a positive electrode other than a positive electrode having a substrate containing metallic aluminum. [Examples]

[0099] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples.

[0100] [Example 1] (Preparation of non-aqueous electrolytes) A non-aqueous solvent was prepared by mixing EC, PC, and EMC in a volume ratio of 20:5:75. Lithium bis(fluorosulfonyl)imide (LiFSI) was added to this non-aqueous solvent at a concentration of 0.90 mol / dm³ as the electrolyte salt. 3 , and 8-quinolinol, which is the compound represented by the above formula (1), at a concentration of 0.7 mol / dm³ 3 The non-aqueous electrolyte of Example 1 was prepared by mixing the respective components according to their respective content.

[0101] [Examples 2 and 3, Comparative Examples 1 and 2, Reference Examples 1 to 3] Non-aqueous electrolytes were prepared in the same manner as in Example 1, except that the content of the electrolyte salts (LiFSI and LiPF6) and 8-quinolinol was as shown in Tables 1 to 3. In Tables 1 to 3, "-" indicates that the corresponding component was not included.

[0102] [evaluation] (Measurement of corrosion initiation potential) The corrosion initiation potential was determined by measuring linear sweep voltammetry (LSV) at a sweeping speed of 5 mV / sec in a trielectrode cell using the above-mentioned non-aqueous electrolytes, with metallic lithium as the counter electrode and reference electrode, and aluminum foil as the working electrode. The measured corrosion initiation potentials are shown in Tables 1 to 3. Regarding the corrosion inhibitory effect of each non-aqueous electrolyte in the examples, a corrosion inhibitory effect was considered "present" if the corrosion initiation potential was higher than that of a comparative example non-aqueous electrolyte that had the same imide salt content and did not contain the compound represented by formula (1) above. The presence or absence of a corrosion inhibitory effect in each example is shown in Tables 2 and 3.

[0103] [Table 1]

[0104] [Table 2]

[0105] [Table 3]

[0106] As shown in Table 1, in the case of a non-aqueous electrolyte containing only LiPF6 as the electrolyte salt, no corrosion of the substrate occurs. On the other hand, in the case of a non-aqueous electrolyte containing the imide salt LiFSI, corrosion of the substrate occurs, and as the imide salt content increases, the corrosion initiation potential decreases, making the substrate more susceptible to corrosion. Furthermore, as shown in Tables 2 and 3, when 8-quinolinol, a compound represented by formula (1) above, is added to a non-aqueous electrolyte containing an imide salt, the corrosion initiation potential increases compared to a comparative example of a non-aqueous electrolyte with the same imide salt content but without the compound represented by formula (1), indicating that corrosion of the substrate can be suppressed. [Industrial applicability]

[0107] The present invention is suitably used as a non-aqueous electrolyte energy storage element, including a non-aqueous electrolyte secondary battery used as a power source for electronic devices such as personal computers and communication terminals, and automobiles. [Explanation of symbols]

[0108] 1. Non-aqueous electrolyte energy storage element 2 Electrode body 3 containers 4 Positive terminal 41 Positive lead 5 Negative terminal 51 Negative lead 20 Energy storage units 30 Energy storage devices

Claims

1. Imide salts, The compound represented by the following formula (1) and A non-aqueous electrolyte for energy storage elements containing a non-aqueous electrolyte. 【Chemistry 1】 In the above formula (1), R １ R is a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. n is an integer between 0 and 6. If n is 2 or greater, multiple R １ They may be the same or different.

2. The content of the above compound is 0.1 mol / dm ３ More than 5mol / dm ３ The non-aqueous electrolyte according to claim 1, which is as follows:

3. A positive electrode having a substrate containing metallic aluminum, Non-aqueous electrolytes and Equipped with, The above non-aqueous electrolytes Imide salts, At least one selected from the group consisting of compounds represented by the following formula (1) and complexes having the above compound as a ligand, A non-aqueous electrolyte energy storage element containing [a specific component]. 【Chemistry 2】 In the above formula (1), R １ R is a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. n is an integer between 0 and 6. If n is 2 or greater, multiple R １ They may be the same or different.

4. To prepare a positive electrode having a substrate containing metallic aluminum, and Prepare a non-aqueous electrolyte. Equipped with, The above non-aqueous electrolytes Imide salts, The compound represented by the following formula (1) and A method for manufacturing a non-aqueous electrolyte energy storage element containing a specific electrolyte. 【Transformation 3】 In the above formula (1), R １ R is a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. n is an integer between 0 and 6. If n is 2 or greater, multiple R １ They may be the same or different.

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