Lithium-ion battery

Abstract

To suppress the elution of aluminum from an aluminum-containing current collector into an electrolyte in a lithium-ion battery.SOLUTION: A lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte. The electrolyte includes an organic solvent and a lithium amide salt dissolved in the organic solvent. The lithium amide salt includes LiCFSA. One or both of the positive electrode and the negative electrode have an aluminum-containing current collector. The aluminum-containing current collector has a coating on the surface in contact with the electrolyte. The coating includes Al(CFSA)x.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This application discloses a lithium ion battery. [Background technology]

[0002] Patent Document 1 discloses an electrolyte solution for an electricity storage device that contains a cyclic lithium sulfonylimide salt, a hydrofluoroether, and a carbonate-based solvent. Patent Document 1 also discloses a lithium ion secondary battery as an example of the electricity storage device. Patent Document 2 discloses a nonaqueous electrolyte solution that contains a carboxylate. Patent Document 3 discloses an electrolyte solution for a lithium ion secondary battery that contains a lithium imide salt, at least one solvent selected from carbonates, esters, ethers, and room temperature molten salts, and at least one of Group 1 elements and Group 2 elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2010 / 110388 [Patent Document 2] JP 2009-129719 A [Patent Document 3] JP 2019-096463 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to make full use of an aluminum-containing current collector in a lithium ion battery, it is necessary to suppress the elution of aluminum from the aluminum-containing current collector into an electrolyte. This application discloses a technology capable of suppressing the elution of aluminum from an aluminum-containing current collector into an electrolyte in a lithium ion battery. [Means for solving the problem]

[0005] The present application discloses the following aspects as means for solving the above problems. <Aspect 1> A lithium ion battery having a positive electrode, a negative electrode, and an electrolyte, The electrolyte solution is an organic solvent, and a lithium amide salt dissolved in said organic solvent; Including, The lithium amide salt comprises LiCFSA represented by the following formula (1): one or both of the positive electrode and the negative electrode has an aluminum-containing current collector; the aluminum-containing current collector has a coating on a surface that comes into contact with the electrolyte, The coating is Al(CFSA) x Including, Lithium-ion battery. [ka] <Aspect 2> 2. The lithium ion battery of embodiment 1, The electrolytic solution contains sulfolane as the organic solvent; Lithium-ion battery. <Aspect 3> 3. The lithium ion battery of embodiment 1 or 2, The electrolytic solution contains a carboxylic acid ester as the organic solvent. Lithium-ion battery. <Aspect 4> The lithium ion battery according to any one of aspects 1 to 3, The coating comprises aluminum fluoride. Lithium-ion battery. <Aspect 5> The lithium ion battery according to any one of aspects 1 to 4, At least the positive electrode has the aluminum-containing current collector. Lithium-ion battery. Effect of the Invention

[0006] According to the lithium ion battery of the present disclosure, it is possible to suppress the elution of aluminum from the aluminum-containing current collector into the electrolyte. [Brief description of the drawings]

[0007] [Figure 1] 1 illustrates a schematic diagram of an example of the configuration of a lithium ion battery. [Diagram 2] 4 shows the results of Al corrosion evaluation for Comparative Example 1. [Diagram 3] 4 shows the results of Al corrosion evaluation for Comparative Example 2. [Figure 4] 4 shows the results of Al corrosion evaluation for Comparative Example 3. [Diagram 5] 4 shows the results of Al corrosion evaluation for Comparative Example 4. [Figure 6] 4 shows the results of Al corrosion evaluation for Comparative Example 5. [Figure 7] 4 shows the results of Al corrosion evaluation for Example 1. [Figure 8] 4 shows the results of Al corrosion evaluation for Example 2. [Figure 9] 4 shows the results of Al corrosion evaluation for Example 3. [Figure 10] 1 shows the results of XPS analysis of a coating formed on the surface of an aluminum-containing current collector at 4 V (XPS spectrum for Al2p). [Figure 11] 1 shows the results of XPS analysis of a coating formed on the surface of an aluminum-containing current collector at 4 V (XPS spectrum for F1s). [Figure 12] 1 shows the results of XPS analysis (XPS spectrum for S2p) of a coating formed on the surface of an aluminum-containing current collector at 4 V. [Figure 13] 1 shows the results of XPS analysis of a coating formed on the surface of an aluminum-containing current collector at 6 V (XPS spectrum for Al2p). [Figure 14]1 shows the results of XPS analysis of a coating formed on the surface of an aluminum-containing current collector at 6 V (XPS spectrum for F1s). [Figure 15] 1 shows the results of XPS analysis (XPS spectrum for S2p) of a coating formed on the surface of an aluminum-containing current collector at 6 V. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, one embodiment of the lithium ion battery etc. of the present disclosure will be described, however, the lithium ion battery etc. of the present disclosure is not limited to the embodiment described below.

[0009] 1. Lithium-ion battery As shown in FIG. 1, a lithium ion battery 100 according to one embodiment includes a positive electrode 10, a negative electrode 20, and an electrolyte 30. The electrolyte 30 includes an organic solvent and a lithium amide salt dissolved in the organic solvent. The lithium amide salt includes LiCFSA represented by the following formula (1). One or both of the positive electrode 10 and the negative electrode 20 include an aluminum-containing current collector. The aluminum current collector includes a coating 50 on a surface that contacts the electrolyte 30. The coating 50 includes Al(CFSA) x Includes. [ka]

[0010] 1.1 Positive electrode As shown in FIG. 1, a positive electrode 10 according to an embodiment may include a positive electrode active material layer 11 and a positive electrode current collector 12. When a negative electrode current collector 22 described later is an aluminum-containing current collector, the positive electrode current collector 12 may or may not be an aluminum-containing current collector. When a negative electrode current collector 22 described later is not an aluminum-containing current collector, the positive electrode current collector 12 is an aluminum-containing current collector. In particular, the elution of aluminum from an aluminum-containing current collector into the electrolyte is likely to occur when the aluminum-containing current collector is at a high potential. However, according to the technology of the present disclosure, even when at least the positive electrode 10 has an aluminum-containing current collector, the elution of aluminum into the electrolyte 30 can be suppressed.

[0011] 1.1.1 Cathode active material layer The positive electrode active material layer 11 includes a positive electrode active material, and may further include an electrolyte, a conductive assistant, a binder, and various additives. The content of each of the positive electrode active material, electrolyte, conductive assistant, binder, and the like in the positive electrode active material layer 11 may be appropriately determined according to the target battery performance. For example, the content of the positive electrode active material may be 40 mass% or more, 50 mass% or more, or 60 mass% or more, or less than 100 mass% or 90 mass% or less, with the entire positive electrode active material layer 11 (total solid content) being 100 mass%. The shape of the positive electrode active material layer 11 is not particularly limited, and may be, for example, a sheet shape having a substantially flat surface. The thickness of the positive electrode active material layer 11 is not particularly limited, and may be, for example, 0.1 μm or more, 1 μm or more, 10 μm or more, or 30 μm or more, and may be 2 mm or less, 1 mm or less, 500 μm or less, or 100 μm or less.

[0012] The positive electrode active material may be a known positive electrode active material for a lithium ion battery. Among known active materials, a material whose potential (charge / discharge potential) for absorbing and releasing lithium ions is higher than that of the negative electrode active material described below may be used as the positive electrode active material. For example, various lithium-containing composite oxides such as lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium manganese nickel cobalt oxide, and spinel-based lithium compounds may be used as the positive electrode active material. Only one type of positive electrode active material may be used alone, or two or more types may be used in combination. The positive electrode active material may be, for example, particulate, and the size is not particularly limited. The particles of the positive electrode active material may be solid particles or hollow particles. The particles of the positive electrode active material may be primary particles or secondary particles formed by agglomeration of a plurality of primary particles. The average particle diameter (D50) of the particles of the positive electrode active material may be, for example, 1 nm or more, 5 nm or more, or 10 nm or more, and may be 500 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. The average particle diameter (D50) is the particle diameter (D50, median diameter) at an integrated value of 50% in a volume-based particle size distribution by a laser diffraction / scattering method.

[0013] The surface of the positive electrode active material may be covered with a protective layer containing a lithium ion conductive oxide. That is, the positive electrode active material layer 11 may include a composite having the above positive electrode active material and a protective layer provided on the surface thereof. The lithium ion conductive oxide may be, for example, Li 3 BO 3 , LiBO 2 , Li 2 CO 3 , LiAlO 2 , Li 4 SiO 4 , Li 2 SiO 3 , Li 3 PO 4 , Li 2 SO 4 , Li 2 TiO 3 , Li 4 Ti 5 O12 , Li 2 Ti 2 O 5 , Li 2 ZrO 3 , LiNbO 3 , Li 2 MoO 4 , Li 2 WO 4 The coverage (area ratio) of the protective layer may be, for example, 70% or more, 80% or more, or 90% or more. The thickness of the protective layer may be, for example, 0.1 nm or more or 1 nm or more, and may be 100 nm or less, or 20 nm or less.

[0014] The positive electrode active material layer 11 may contain an electrolyte solution 30, which will be described later. The positive electrode active material layer 11 may contain other electrolytes in addition to the electrolyte solution 30. The other electrolytes may be solid electrolytes, electrolyte solutions other than the electrolyte solution 30, or combinations thereof. The solid electrolyte may be any known solid electrolyte for lithium ion batteries. The solid electrolyte may be an inorganic solid electrolyte or an organic polymer electrolyte. In particular, inorganic solid electrolytes are excellent in ion conductivity and heat resistance. Examples of inorganic solid electrolytes include sulfide solid electrolytes and oxide solid electrolytes. In particular, sulfide solid electrolytes, particularly sulfide solid electrolytes containing at least Li, S, and P as constituent elements, have high performance, and Li 3 P.S. 4 The performance of a sulfide solid electrolyte based on a skeleton and containing at least one type of halogen is also high. The solid electrolyte may be amorphous or crystalline. The solid electrolyte may be, for example, particulate. Only one type of solid electrolyte may be used alone, or two or more types may be used in combination. An electrolyte solution other than the electrolyte solution 30 (other electrolyte solution) may contain, for example, lithium ions as carrier ions. The other electrolyte solution may be, for example, a non-aqueous electrolyte solution. For example, a carbonate-based solvent in which a lithium salt is dissolved at a predetermined concentration may be used as the other electrolyte solution.

[0015] Examples of the conductive assistant that may be included in the positive electrode active material layer 11 include carbon materials such as vapor grown carbon fiber (VGCF), acetylene black (AB), ketjen black (KB), carbon nanotubes (CNT), and carbon nanofibers (CNF); and metal materials such as nickel, aluminum, and stainless steel. The conductive assistant may be, for example, particulate or fibrous, and the size is not particularly limited. Only one type of conductive assistant may be used alone, or two or more types may be used in combination.

[0016] Examples of binders that can be included in the positive electrode active material layer 11 include butadiene rubber (BR)-based binders, butylene rubber (IIR)-based binders, acrylate butadiene rubber (ABR)-based binders, styrene butadiene rubber (SBR)-based binders, polyvinylidene fluoride (PVdF)-based binders, polytetrafluoroethylene (PTFE)-based binders, polyimide (PI)-based binders, polyacrylic acid-based binders, etc. Only one type of binder may be used alone, or two or more types may be used in combination.

[0017] 1.1.2 Positive electrode current collector As shown in FIG. 1, the positive electrode 10 may include a positive electrode collector 12 in contact with the positive electrode active material layer 11 and the electrolyte 30. The positive electrode collector 12 may be any of those commonly used as positive electrode collectors for lithium ion batteries. The positive electrode collector 12 may be in the form of a foil, a plate, a mesh, a punched metal, a foam, or the like. The positive electrode collector 12 may be made of a metal foil or a metal mesh. In particular, the metal foil is excellent in terms of ease of handling. The positive electrode collector 12 may be made of a plurality of foils. Examples of metals constituting the positive electrode collector 12 include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, and the like. As described above, the positive electrode 10 may include an aluminum-containing collector in contact with the positive electrode active material layer 11 and the electrolyte 30 as the positive electrode collector 12, in which case oxidation resistance and the like are easily ensured. The positive electrode current collector 12 may have some kind of coating layer on its surface for the purpose of adjusting the resistance, etc. Also, the positive electrode current collector 12 may be a metal foil or a base material on which the above metal is plated or vapor-deposited. Also, when the positive electrode current collector 12 is made of a plurality of metal foils, some kind of layer may be present 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 more, and may be 1 mm or less or 100 μm or less.

[0018] In addition to the above configuration, the positive electrode 10 may have a general configuration as a positive electrode of a lithium ion battery. For example, a tab, a terminal, etc. The positive electrode 10 can be manufactured by applying a known method. For example, the positive electrode active material layer 11 can be easily formed by forming a positive electrode mixture containing the above various components in a dry or wet manner. The positive electrode active material layer 11 may be formed together with the positive electrode current collector 12, or may be formed separately from the positive electrode current collector 12.

[0019] 1.2 Negative electrode 1, the negative electrode 20 according to one embodiment may include a negative electrode active material layer 21 and a negative electrode current collector 22. When the above-mentioned positive electrode current collector 12 is an aluminum-containing current collector, the negative electrode current collector 22 may or may not be an aluminum-containing current collector. When the above-mentioned positive electrode current collector 12 is not an aluminum-containing current collector, the negative electrode current collector 22 is an aluminum-containing current collector.

[0020] 1.2.1 Negative electrode active material layer The negative electrode active material layer 21 includes a negative electrode active material, and may further include an electrolyte, a conductive assistant, a binder, various additives, and the like. The contents of the negative electrode active material, electrolyte, conductive assistant, binder, and the like in the negative electrode active material layer 21 may be appropriately determined according to the target battery performance. For example, the content of the negative electrode active material may be 40 mass% or more, 50 mass% or more, or 60 mass% or more, or less than 100 mass% or 90 mass% or less, with the entire negative electrode active material layer 21 (total solid content) being 100 mass%. The shape of the negative electrode active material layer 21 is not particularly limited, and may be, for example, a sheet shape having a substantially flat surface. The thickness of the negative electrode active material layer 21 is not particularly limited, and may be, for example, 0.1 μm or more, 1 μm or more, 10 μm or more, or 30 μm or more, and may be 2 mm or less, 1 mm or less, 500 μm or less, or 100 μm or less.

[0021] The negative electrode active material may be any known material for a lithium ion battery. Of the known active materials, any material that has a potential (charge / discharge potential) for absorbing and releasing lithium ions that is lower than that of the positive electrode active material may be used as the negative electrode active material. For example, 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, and the like may be used as the negative electrode active material. Only one type of negative electrode active material may be used alone, or two or more types may be used in combination. The negative electrode active material may be, for example, particulate, and the size is not particularly limited. The particles of the negative electrode active material may be solid particles or hollow particles. The particles of the negative electrode active material may be primary particles, or may be secondary particles formed by agglomeration of a plurality of primary particles. The average particle diameter (D50) of the negative electrode active material particles may be, for example, 1 nm or more, 5 nm or more, or 10 nm or more, and may be 500 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. Alternatively, the negative electrode active material may be in a sheet form (foil form, film form) such as lithium foil. That is, the negative electrode active material layer 21 may be made of a sheet of the negative electrode active material.

[0022] The negative electrode active material layer 21 may contain an electrolyte solution 30 described later. The negative electrode active material layer 21 may contain other electrolytes in addition to the electrolyte solution 30. Examples of other electrolytes include the above-mentioned solid electrolyte, the electrolyte solution, or a combination of these. The conductive assistant that may be contained in the negative electrode active material layer 21 may be appropriately selected from, for example, those exemplified as the conductive assistant that may be contained in the above-mentioned positive electrode active material layer 11. The binder that may be contained in the negative electrode active material layer 21 may be appropriately selected from, for example, those exemplified as the binder that may be contained in the above-mentioned positive electrode active material layer 11. Each of the electrolyte, the conductive assistant, and the binder may be used alone or in combination of two or more kinds.

[0023] 1.2.2 Negative electrode current collector As shown in FIG. 1, the negative electrode 20 may include a negative electrode current collector 22 in contact with the negative electrode active material layer 21 and the electrolyte solution 30. The negative electrode current collector 22 may be any of those commonly used as a negative electrode current collector for a battery. The negative electrode current collector 22 may be in the form of a foil, a plate, a mesh, a punched metal, a foam, or the like. The negative electrode current collector 22 may be a metal foil or a metal mesh, or may be a carbon sheet. In particular, a metal foil is excellent in terms of ease of handling. The negative electrode current collector 22 may be made of a plurality of foils or sheets. Examples of metals constituting the negative electrode current collector 22 include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, and the like. From the viewpoint of ensuring reduction resistance and being difficult to alloy with lithium, the negative electrode current collector 22 may contain at least one metal selected from Cu, Ni, and stainless steel. Alternatively, as described above, the negative electrode 20 may include, as the negative electrode collector 22, an aluminum-containing current collector in contact with the negative electrode active material layer 21 and the electrolyte solution 30. The negative electrode collector 22 may have some kind of coating layer on its surface for the purpose of adjusting the resistance or the like. The negative electrode collector 22 may also be a metal foil or a base material on which the above metal is plated or vapor-deposited. When the negative electrode collector 22 is made of a plurality of metal foils, some kind of layer may be present between the plurality of metal foils. The thickness of the negative electrode collector 22 is not particularly limited. For example, it may be 0.1 μm or more or 1 μm or more, and may be 1 mm or less or 100 μm or less.

[0024] In addition to the above configuration, the negative electrode 20 may have a general configuration as a negative electrode of a lithium ion battery. For example, a tab, a terminal, etc. The negative electrode 20 can be manufactured by applying a known method. For example, the negative electrode active material layer 21 can be easily formed by forming a negative electrode mixture containing the above various components in a dry or wet manner. The negative electrode active material layer 21 may be formed together with the negative electrode current collector 22 or may be formed separately from the negative electrode current collector 22.

[0025] 1.3 Electrolyte The electrolyte solution 30 includes an organic solvent and a lithium amide salt dissolved in the organic solvent.

[0026] 1.3.1 Organic solvents The electrolytic solution 30 includes an organic solvent. Any of the known organic solvents used in the electrolytic solution of lithium ion batteries can be used as the organic solvent. In any case where any of the organic solvents is used, a coating 50 is formed on the surface of the aluminum-containing current collector by the lithium amide salt described below, and the elution of aluminum from the aluminum-containing current collector into the electrolytic solution 30 can be suppressed. The organic solvent may be, for example, a sulfone, a carbonate, a carboxylate, or a combination thereof.

[0027] Sulfones are sulfonyl groups (-S(=O) 2 -). The sulfones may be cyclic or chain sulfones. The sulfones may be liquid at a temperature at which lithium ion conductivity is desired to be exhibited and may dissolve the lithium amide salt. When the electrolyte solution 30 contains a sulfone as an organic solvent, it is considered that the transport number of the lithium ion is improved by a hopping-like conduction mechanism via the O site of the sulfonyl group. In addition, it is considered that the sulfones contribute to the formation of the coating 50 together with the lithium amide salt described later, and the stability of the coating 50 is improved. In particular, when the electrolyte solution 30 contains a cyclic sulfone as the organic solvent, and particularly when it contains sulfolane, the transport number is more likely to be improved. The sulfones as the organic solvent may be used alone as one type, or may be used in combination of two or more types. The amount of sulfones as the organic solvent contained in the electrolytic solution 30 may be 50 mol % or more, 60 mol % or more, 70 mol % or more, 80 mol % or more, 90 mol % or more, 95 mol % or more, 97 mol % or more, or 99 mol % or more, with the entire organic solvent being 100 mol %.

[0028] The carbonates have a carbonate group (-O-(C=O)-O-). The carbonates may be cyclic carbonates or chain carbonates. The carbonates may be liquid at a temperature at which lithium ion conductivity is desired to be exhibited and may dissolve lithium amide salt. In particular, cyclic carbonates have a higher dielectric constant than chain carbonates and are more likely to coordinate lithium ions. In other words, when the electrolyte solution 30 contains a cyclic carbonate as an organic solvent, the cyclic carbonate is less likely to be in a free state, and as a result, the thermal stability is more likely to be improved. Specific examples of cyclic carbonates include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), vinylene carbonate (VC), or derivatives thereof (e.g., halides, etc.). In particular, when the cyclic carbonate is at least one of propylene carbonate and ethylene carbonate, it is easy to ensure better lithium ion conductivity and thermal stability. Examples of the chain carbonate include dimethyl carbonate (DMC), diethyl carbonate (DEC), or derivatives thereof (e.g., halides, particularly those having a perfluoroalkyl group). However, the chain carbonate has a lower dielectric constant than the cyclic carbonate, and tends to be difficult for lithium ions to coordinate. As the organic solvent, only one type of carbonate may be used alone, or two or more types may be used in combination. The amount of the carbonate as the organic solvent contained in the electrolytic solution 30 may be 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more, based on the total amount of the organic solvent being 100 mol%.

[0029] The carboxylate ester has an ester group (-(C=O)-O-). The carboxylate ester as an organic solvent may have a function of dissociating lithium ions from the lithium amide salt described later by the action of the ester group. The carboxylate ester as an organic solvent may have a function of reducing the viscosity of the electrolyte solution 30. Therefore, when the electrolyte solution 30 contains a carboxylate ester as an organic solvent, the ionic conductivity of the electrolyte solution 30 is likely to be improved. The carboxylate ester may be a monocarboxylate ester or a polycarboxylate ester such as a dicarboxylate ester or a tricarboxylate ester. In particular, when the electrolyte solution 30 contains a monocarboxylate ester as an organic solvent, the ionic conductivity of the electrolyte solution 30 is likely to be improved more significantly. The carboxylate ester may be an aliphatic carboxylate ester or an aromatic carboxylate ester. In particular, when the electrolyte solution 30 contains an aliphatic carboxylate ester as an organic solvent, the ionic conductivity of the electrolyte solution 30 is likely to be improved more significantly. In particular, when the electrolyte solution 30 contains a carboxylate ester represented by the following formula (1) as an organic solvent, the ionic conductivity of the electrolyte solution 30 is likely to be increased more significantly.

[0030] R 1 -(C=O)-OR 2 (1) R 1 : a hydrocarbon group having 1 to 4 carbon atoms, for example, an alkyl group having 1 to 4 carbon atoms R 2 : a hydrocarbon group having 1 to 4 carbon atoms, for example, an alkyl group having 1 to 4 carbon atoms

[0031] In the above formula (1), R 1 When R is an alkyl group having 1 to 3 carbon atoms, particularly an alkyl group having 2 to 3 carbon atoms, the ionic conductivity of the electrolyte solution 30 is likely to be significantly improved. 2 When R is an alkyl group having 1 to 3 carbon atoms, particularly when R is an alkyl group having 1 to 2 carbon atoms, the ionic conductivity of the electrolyte solution 30 is likely to be significantly improved. 1 The number of carbon atoms and R 2The total number of carbon atoms may be, for example, 2 or more and 6 or less, 3 or more and 5 or less, or 3 or 4. Specific examples of the carboxylate ester include ethyl formate, methyl isobutyrate, methyl acetate, and methyl propionate. In particular, when the electrolytic solution 30 contains methyl propionate as an organic solvent, the ionic conductivity of the electrolytic solution 30 is likely to be significantly improved.

[0032] The electrolytic solution 30 may contain both the carbonates and the carboxylate ester. In this case, the ionic conductivity of the electrolytic solution 30 is likely to be further significantly increased. For example, the electrolytic solution 30 may contain carbonates as an organic solvent and carboxylate ester as an organic solvent, the ratio of carbonates to the total organic solvent contained in the electrolytic solution 30 may be 5% by volume or more and 95% by volume or less, 5% by volume or more and 50% by volume or less, or 10% by volume or more and 20% by volume or less, the ratio of carboxylate ester to the total organic solvent contained in the electrolytic solution 30 may be 5% by volume or more and 95% by volume or less, 50% by volume or more and 95% by volume or less, or 80% by volume or more and 90% by volume or less, and the total ratio of carbonates and carboxylate ester to the total organic solvent contained in the electrolytic solution 30 may be 50% by volume or more and 100% by volume or less, 75% by volume or more and 100% by volume or less, or 90% by volume or more and 100% by volume or less.

[0033] The electrolytic solution 30 may contain other organic solvents. Examples of other organic solvents include ethers. The amount of ethers as the organic solvent contained in the electrolytic solution 30 may be 5 mol % or less, 3 mol % or less, or 1 mol % or less, with the entire organic solvent being 100 mol %. Alternatively, the electrolytic solution 30 may not contain ethers.

[0034] 1.3.2 Lithium amide salts The electrolyte solution 30 contains a lithium amide salt dissolved in the organic solvent. In the electrolyte solution 30, the lithium amide salt may be dissolved in the organic solvent and ionized into a cation and an anion, or may form some kind of association. In the present application, the term "amide salt" includes the concept of "imide salt."

[0035] 1.3.2.1 LiCFSA The lithium amide salt contains LiCFSA (lithium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide) represented by the above formula (1). According to the new findings of the present inventors, when a lithium ion battery 100 is constructed using an electrolyte solution 30 in which LiCFSA is dissolved, and the lithium ion battery 100 is charged and discharged, a coating 50 derived from LiCFSA can be formed on the surface of the aluminum-containing current collector. For example, when the potential of the aluminum-containing current collector is 4.0 V (vs. Li / Li + When the CFSA anion is adsorbed on the surface of the aluminum-containing current collector to form a coating 50 derived from the CFSA anion, the coating 50 is an Al(CFSA) x Here, "Al(CFSA) x " means that Al derived from the aluminum-containing current collector and CFSA anion derived from LiCFSA are adsorbed and bonded to each other. The value of x is not particularly limited. Al(CFSA) x When the coating 50 containing Al(CFSA) is formed, the coating 50 functions as a protective film, and even if the aluminum-containing current collector is at a high potential, it is possible to suppress the elution of aluminum from the aluminum-containing current collector into the electrolyte 30. Note that when the coating formed on the surface of the aluminum-containing current collector is Al(CFSA), x Whether or not the compound contains the above can be confirmed by, for example, X-ray photoelectron spectroscopy (XPS).

[0036] LiPF as lithium salt in organic solvent as electrolyte for lithium-ion batteries 6 As far as the inventors have confirmed, LiPF 6Decomposes at a high potential, which can form a coating of fluoride on the surface of the current collector. 6 When a coating film derived from LiCFSA is formed, the electrolyte decomposes at the same time, which causes the generation of gas. In contrast, in the lithium-ion battery 100 of the present disclosure, the potential of the aluminum current collector is 4.0 V (vs. Li / Li + ), the CFSA anion is adsorbed on the surface of the aluminum-containing current collector to form the coating 50. + ), decomposition of the electrolyte solution 30 is unlikely to occur. That is, in the lithium-ion battery 100 of the present disclosure, it can be said that the coating 50 can be formed on the surface of the aluminum-containing current collector while suppressing decomposition of the electrolyte solution 30 and suppressing gas generation.

[0037] The concentration of LiCFSA in the electrolytic solution 30 is not particularly limited, and whether the concentration is low or high, the above-mentioned coating 50 is formed on the surface of the aluminum-containing current collector, and the aluminum elution suppression effect is exhibited. The molar ratio of LiCFSA to the organic solvent ([LiCFSA (mol)] / [organic solvent (mol)]) may be, for example, 0.01 to 0.50, 0.05 to 0.40, or 0.10 to 0.33. In other words, LiCFSA may be dissolved at a concentration of 0.01 mol to 0.50 mol, 0.05 mol to 0.40 mol, or 0.10 mol to 0.33 mol per mol of organic solvent. When the concentration of LiCFSA dissolved in the organic solvent is within this range, the above-mentioned aluminum elution suppression effect is further enhanced, and the electrolytic solution 30 is likely to have excellent ion conductivity. The molar ratio of LiCFSA to the organic solvent can be specified by analyzing ions, elements, and the like contained in the organic solvent.

[0038] 1.3.2.2 Other lithium amide salts The electrolyte 30 is sufficient if it contains the above-mentioned LiCFSA dissolved therein, and may contain a lithium amide salt other than LiCFSA in addition to the above-mentioned LiCFSA. The lithium amide salt other than LiCFSA may be a chain lithium amide salt or a cyclic lithium amide salt other than LiCFSA. Specific examples of chain lithium amide salts include lithium bisfluorosulfonylamide (LiFSA, LiN(SO 2 F) 2 ), lithium bistrifluoromethanesulfonylamide (LiTFSA, Li[N(CF 3 SO 2 ) 2 ]), lithium bisperfluoroethylsulfonylamide (Li[N(C 2 F 5 SO 2 ) 2 ]), lithium bisperfluorobutylsulfonylamide (Li[N(C 4 F 9 SO 2 ) 2 ]), lithium fluorosulfonyltrifluoromethanesulfonylamide (Li[N(FSO 2 )(C 2 F 5 SO 2)) and the like. Alternatively, a silylamide salt having Si instead of S may be employed. The chain lithium amide salt may be used alone or in combination of two or more. Specific examples of cyclic lithium amide salts other than LiCFSA include the above-mentioned sulfonylamide salts and silylamide salts in which sulfonylamide groups or silylamide groups form a ring via a perfluoroalkylene group or the like. The concentration of the other lithium amide salt in the electrolytic solution 30 is not particularly limited, and may be low or high. In the electrolytic solution 30, the proportion of LiCFSA in the lithium amide salt dissolved in the solvent may be high, and specifically, the proportion of LiCFSA in the entire lithium amide salt (100 mol%) may be 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, or 99 mol% or more. Alternatively, in electrolyte 30, the proportion of LiCFSA in the lithium amide salt dissolved in the solvent may be low; specifically, the proportion of LiCFSA in the entire lithium amide salt (100 mol%) may be 50 mol% or less, 40 mol% or less, 30 mol% or less, or 20 mol% or less.

[0039] 1.3.3 Lithium salts other than lithium amide salts In the electrolytic solution 30, the lithium salt dissolved in the organic solvent may be the lithium amide salt described above, or may be a combination of the lithium amide salt described above and a lithium salt other than the lithium amide salt (other lithium salt). In the electrolytic solution 30, the proportion of the lithium amide salt in the lithium salt dissolved in the solvent may be high, specifically, the proportion of the lithium amide salt in the total lithium salt (100 mol%) may be 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, or 99 mol% or more. Alternatively, in the electrolytic solution 30, the proportion of the lithium amide salt in the lithium salt dissolved in the solvent may be low, specifically, the proportion of the lithium amide salt in the total lithium salt (100 mol%) may be 50 mol% or less, 40 mol% or less, 30 mol% or less, or 20 mol% or less.

[0040] 1.3.4 Other optional ingredients The electrolyte solution 30 may contain various additives in addition to the organic solvent and the lithium amide salt to the extent that the above-mentioned problems can be solved. The type of additive may be appropriately selected according to the desired performance. The electrolyte solution 30 may also be combined with a solid material (e.g., a solid electrolyte).

[0041] 1.4 Coating As described above, in the lithium ion battery 100, one or both of the positive electrode 10 and the negative electrode 20 have an aluminum-containing current collector, and the aluminum-containing current collector has a composition of Al(CFSA) at the contact surface with the electrolyte 30. x As described above, the coating 50 has a potential of 4.0 V (vs. Li / Li + ) on the surface of the aluminum-containing current collector. According to the new findings of the present inventors, in the lithium-ion battery 100, the CFSA anion may be formed by adsorption of the CFSA anion on the surface of the aluminum-containing current collector until the potential of the aluminum-containing current collector reaches about 6.0 V (vs. Li / Li + ) on the surface of the aluminum-containing current collector. xIn other words, the coating 50 may contain aluminum fluoride. In this way, Al(CFSA) x The coating 50 containing aluminum fluoride can also suppress the elution of aluminum from the aluminum-containing current collector into the electrolyte 30. Alternatively, the coating 50 may be Al(CFSA) x As described above, the coating 50 may contain Al(CFSA) x By only containing Al(CFSA), it is possible to suppress the elution of aluminum from the aluminum-containing current collector into the electrolyte 30. x and aluminum fluoride (AlF x Whether or not a material contains .DELTA..DELTA..sub.1, .DELTA..sub.2, .DELTA..sub.3, .DELTA..sub.4, or .DELTA..sub.5 can be confirmed by, for example, X-ray photoelectron spectroscopy (XPS).

[0042] As shown in FIG. 1, the coating 50 may be formed on the surface of an aluminum-containing current collector as the positive electrode current collector 12. Alternatively, the coating 50 may be formed on the surface of an aluminum-containing current collector as the negative electrode current collector 22. Alternatively, the coating 50 may be formed on the surface of both the aluminum-containing current collector as the positive electrode current collector 12 and the aluminum-containing current collector as the negative electrode current collector 22. In particular, when the coating 50 is formed at least on the surface of the aluminum-containing current collector as the positive electrode current collector 12, a higher effect is likely to be obtained. The thickness of the coating 50 is not particularly limited. The thickness of the coating 50 may be, for example, more than 0 μm and 10 μm or less. Alternatively, the thickness of the coating 50 may be, for example, more than 10 μm. In particular, when the thickness of the coating 50 is more than 0 μm and 10 μm or less, the above-mentioned aluminum elution suppression effect is ensured, while other performance balance as a battery is likely to be good. The coating 50 may be formed on the entire contact surface between the aluminum-containing current collector and the electrolyte 30, or may be formed on only a part of the contact surface.

[0043] 1.4 Other matters The lithium ion battery 100 may have a separator 40 between the positive electrode 10 and the negative electrode 20, and the above-mentioned electrolyte 30 may be held in the separator 40. The separator 40 may be a separator known as a separator for the lithium ion battery 100. The lithium ion battery 100 may be one in which each of the above-mentioned components is housed inside an exterior body. Any known exterior body for a battery may be used as the exterior body. A plurality of lithium ion batteries 100 may be electrically connected and stacked in any manner to form an assembled battery. In this case, the assembled battery may be housed inside a known battery case. The lithium ion battery 100 may also have other obvious configurations such as necessary terminals. Examples of the shape of the lithium ion battery 100 include a coin type, a laminate type, a cylindrical type, and a square type. The lithium ion battery 100 may be a secondary battery. The lithium ion battery 100 can be manufactured by applying a known method. For example, it can be manufactured as follows. However, the method for manufacturing the lithium ion battery 100 is not limited to the following method, and each layer may be formed by, for example, dry molding or the like. (1) 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. The positive electrode slurry is applied to the surface of a positive electrode current collector using a doctor blade or the like, and then dried to form a positive electrode active material layer on the surface of the positive electrode current collector, thereby forming a positive electrode. (2) The negative electrode active material constituting the 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. The negative electrode slurry is applied to the surface of the negative electrode current collector using a doctor blade or the like, and then dried to form a negative electrode active material layer on the surface of the negative electrode current collector, thereby forming a negative electrode. (3) The layers are laminated so that the electrolyte layer (separator) is sandwiched between the negative electrode and the positive electrode to obtain a laminate having the negative electrode current collector, the negative electrode active material layer, the electrolyte layer, the positive electrode active material layer, and the positive electrode current collector in this order. Other members such as terminals are attached to the laminate as necessary. (4) The laminate is housed in a battery case, and the laminate is immersed in an electrolyte solution and sealed in the battery case to produce a lithium ion battery. Note that the electrolyte solution may be impregnated into the negative electrode active material layer, the separator, and the positive electrode active material layer in the above step (3).

[0044] 2. Lithium ion conductive materials The technology of the present disclosure has an aspect as a lithium ion conductive material. That is, the lithium ion conductive material of the present disclosure includes an organic solvent and a lithium amide salt dissolved in the organic solvent, and the lithium amide salt includes LiCFSA represented by the above formula (1). Details of each component constituting the lithium ion conductive material are as described above.

[0045] 3. Vehicles The lithium ion battery of the present disclosure can be suitably used in at least one vehicle selected from, for example, a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), and an electric vehicle (BEV). That is, the technology of the present disclosure is a vehicle equipped with a lithium ion battery, the lithium ion battery having a positive electrode, a negative electrode, and an electrolyte, the electrolyte containing an organic solvent and a lithium amide salt dissolved in the organic solvent, the lithium amide salt containing LiCFSA represented by the above formula (1), one or both of the positive electrode and the negative electrode having an aluminum-containing current collector, the aluminum-containing current collector having a coating on a surface in contact with the electrolyte, the coating being Al(CFSA) x It also has an aspect of including. EXAMPLES

[0046] The technology of the present disclosure will be described in more detail below with reference to examples, but the technology of the present disclosure is not limited to the following examples. All of the following experiments were carried out in an Ar atmosphere with a dew point of -80°C or less and an oxygen concentration of less than 3 ppm in a glove box or a similar environment not exposed to the atmosphere.

[0047] 1. Preparation of Electrolyte 1.1 Comparative Example 1 An LBG electrolyte solution manufactured by Kishida Chemical Co., Ltd. was prepared as the electrolyte solution according to Comparative Example 1. The electrolyte solution according to Comparative Example 1 was prepared by dissolving LiPF at a concentration of 1M in a mixed organic solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). 6 The above is dissolved.

[0048] 1.2 Comparative Example 2 The electrolyte solution of Comparative Example 2 was obtained by weighing out each of the propylene carbonate (PC) as an organic solvent and the lithium amide salt, lithium bis(fluorosulfonyl)amide (LiFSA), so that the molar ratio of the propylene carbonate (PC) as an organic solvent was 0.33 (PC:LiFSA=3:1), and mixing and stirring the mixture.

[0049] 1.3 Comparative Example 3 The electrolyte solution according to Comparative Example 3 was obtained by weighing out each component so that the molar ratio of lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) as a lithium amide salt to PC was 0.33 (PC:LiTFSA=3:1), mixing and stirring.

[0050] 1.4 Comparative Example 4 The organic solvent, sulfolane (SL, melting point 27.8° C.), was weighed out so that the molar ratio of LiFSA to the organic solvent was 0.10 (SL:LiFSA=10:1), and the mixture was mixed and stirred to obtain an electrolyte solution according to Comparative Example 4.

[0051] 1.5 Comparative Example 5 The SL and LiFSA were weighed out so that the molar ratio of LiFSA to SL was 0.33 (SL:LiFSA=3:1), and the mixture was mixed and stirred to obtain an electrolyte solution according to Comparative Example 5.

[0052] 1.6 Example 1 The electrolyte solution of Example 1 was obtained by weighing, mixing, and stirring each component so that the molar ratio of lithium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide (LiCFSA) as a lithium amide salt to SL was 0.10 (SL:LiCFSA=10:1).

[0053] 1.7 Example 2 The SL and LiCFSA were weighed, mixed and stirred so that the molar ratio of SL to LiCFSA was 0.33 (SL:LiCFSA=3:1), to obtain the electrolyte according to Example 2. The electrolyte according to Example 3 was a solid at room temperature (25° C.) but a liquid at 60° C., and could be used as an electrolytic solution.

[0054] 1.8 Example 3 The components were weighed, mixed and stirred so that the molar ratio of LiCFSA to PC was 0.10 (PC:LiCFSA=10:1), thereby obtaining an electrolyte solution according to Example 3.

[0055] 2. Evaluation of ionic conductivity and transport number A two-electrode symmetrical cell with fixed electrode area and electrode distance was prepared using Li metal for the electrode and the above-mentioned various electrolytes for the electrolyte, and the resistance was measured by AC impedance method at 25°C. The ionic conductivity was calculated from the obtained resistance value and the cell shape (electrode area, electrode distance). The transport number was calculated by Bruce method, which combines DC polarization and impedance method. The impedance measurement conditions and DC polarization conditions are as follows. Impedance measurement conditions: Temperature 25℃, Amplitude 10mV, Frequency 1M~10mHz DC polarization conditions: Temperature 25℃, applied voltage 10mV, retention time 10h

[0056] 3. Aluminum corrosion evaluation A half cell was prepared using Al foil as the working electrode, Li metal as the counter electrode, and each of the electrolyte solutions according to the above-mentioned Examples and Comparative Examples, and the presence or absence of Al dissolution into the electrolyte solution (Al corrosivity) was evaluated by cyclic voltammetry (CV measurement). The specific measurement conditions are as follows. Measurement conditions: Sweep speed 10mV / s, OCV→(6V→3V), Number of cycles: 5 cycles

[0057] 4. Analysis of the coating on Al foil by XPS 4.1 About the coating after holding 4V A half-cell was prepared using Al foil as a working electrode, Li metal as a counter electrode, and each of the electrolyte solutions according to the above-mentioned Examples 1 to 3 and Comparative Example 1. After the half-cell was held at 4 V, the Al foil was recovered from the half-cell and washed with dimethyl ether (DME), and then the Al foil surface was analyzed by XPS.

[0058] 4.2 Film after holding 6V A half-cell was prepared using Al foil as a working electrode, Li metal as a counter electrode, and each of the electrolytes according to Examples 1 and 3. The half-cell was held at 6 V, and then the Al foil was recovered from the half-cell and washed with dimethyl ether (DME), after which the Al foil surface was analyzed by XPS.

[0059] 5. Evaluation Results Table 1 below shows the composition of the electrolyte, ion conductivity and transport number, the presence or absence of Al corrosion behavior, and the components contained in the coating formed on the Al foil surface for each of Examples 1 to 3 and Comparative Examples 1 to 5. Figs. 2 to 9 show the CV measurement results for each of Comparative Examples 1 to 5 and Examples 1 to 3. Figs. 10 to 12 show the XPS analysis results for the coating formed on the Al foil surface after holding at 4 V for each of Comparative Example 1 and Examples 1 to 3. Figs. 13 to 15 show the XPS analysis results for the coating formed on the Al foil surface after holding at 6 V for each of Examples 1 and 3.

[0060] [Table 1]

[0061] The results shown in Table 1 and FIGS. 2 to 12 reveal the following.

[0062] 3 to 6, in the CV measurements of Comparative Examples 2 to 5, the current value increased when the potential was scanned in the less noble direction after turning back from 6 V, compared to when the potential was scanned in the more noble direction to 6 V. This means that the Al foil was corroded and Al was dissolved into the electrolyte.

[0063] 2 and 7 to 9, in the CV measurements of Comparative Example 1 and Examples 1 to 3, the current value was smaller during potential scanning in the less noble direction after turning back at 6 V than during potential scanning in the more noble direction to 6 V. This means that the dissolution of Al into the electrolyte was suppressed.

[0064] As shown in FIG. 6 In the comparative example 1 using LiPF, the current was confirmed to rise from about 3 V in the first cycle in the CV measurement, and it was confirmed that the current had a peak top at about 3.7 V. From the results of the film analysis on the Al foil by XPS shown in Figures 10 to 12, it was found that the peak top at about 3.7 V was due to LiPF 6 This is thought to correspond to the decomposition current of LiPF 6 The decomposition of aluminum fluoride (AlF x It can be seen that a coating containing LiPF was formed. 6 The decomposition of acetylene generates gas, and a process and mechanism are required to remove the gas from within the cell. If the gas remains within the cell, the performance of the cell may deteriorate due to a reduction in the conductive path and reaction area.

[0065] As shown in Figures 7 to 9, in Examples 1 to 3 using LiCFSA, in the CV measurement, no increase in current was confirmed up to about 3.7 V. From the results of the film analysis on the Al foil by XPS shown in Figures 10 to 12, it was found that AlF x 10, a coating film due to the adsorption of CFSA anion was confirmed on the surface of the Al foil in Examples 1 to 3. Specifically, as shown in FIG. x In FIG. 10, the Al film present on the surface of the Al foil (under the film) was 2 O 3 was also detected, and Al(CFSA) x It can be seen that the coating containing CF is a thin coating having a thickness of 10 μm or less. In addition, as shown in FIG. 11, in Examples 1 to 3, the coating on the surface of the Al foil is CF 2 The bonding was due to the CFSA anion. It can also be seen from FIG. 12 that in Examples 1 to 3, a coating due to the CFSA anion was formed on the surface of the Al foil. That is, when a lithium ion battery was constructed using the electrolyte solutions according to Examples 1 to 3, a coating (Al(CFSA)) due to the adsorption of the CFSA anion was formed on the surface of the Al foil at up to 4 V without substantially causing decomposition of the electrolyte solution (solvent and lithium salt). x It can be said that it is possible to form a coating containing Al(CFSA), which can suppress Al corrosion. x Since no decomposition reaction of the electrolyte occurs during the formation of the coating containing the electrolyte, it can be said that gas generation during the formation of the coating, which is an issue in Comparative Example 1, can be suppressed.

[0066] The results shown in Table 1 and Figures 13 to 15 reveal the following. That is, in Examples 1 to 3, the above-mentioned Al(CFSA) was applied to the surface of the Al foil up to 6 V. x Together with aluminum fluoride (AlF xAs described above, when only LiFSA or LiTFSA is used as in Comparative Examples 2 to 5, Al corrosion occurs, whereas when LiCFSA is used as in Examples 1 to 3, the coating suppresses the elution of Al even at a high potential of 6 V.

[0067] The results shown in Table 1 show that a better transference number can be ensured when a sulfone (eg, sulfolane) is used as the organic solvent than when a carbonate is used.

[0068] 6. Summary From the above results, it can be said that the lithium ion battery having the following configurations (1) to (3) can suppress the elution of aluminum from the aluminum-containing current collector into the electrolyte by the coating on the surface of the aluminum-containing current collector. Also, it can be said that when the coating is formed on the surface of the aluminum current collector, the decomposition of the electrolyte can be suppressed, and the generation of gas can be suppressed. (1) A lithium-ion battery has a positive electrode, a negative electrode, and an electrolyte. (2) The electrolyte solution contains an organic solvent and a lithium amide salt dissolved in the organic solvent, and the lithium amide salt contains LiCFSA represented by the above formula (1). (3) One or both of the positive electrode and the negative electrode have an aluminum-containing current collector, the aluminum-containing current collector has a coating on a surface in contact with the electrolyte, and the coating is Al(CFSA) x Includes.

[0069] 7. Further investigation into the organic solvents that make up the electrolyte 7.1 Preparation of electrolyte 7.1.1 Comparative example A Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 3:3:4 to obtain a mixed solvent. LiPF 6 The above were mixed and stirred to a concentration of 1.15 M to obtain an electrolyte solution according to Comparative Example A.

[0070] 7.1.2 Comparative example B Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1 to obtain a mixed solvent. Lithium bis(fluorosulfonyl)amide (LiFSA) as a lithium amide salt was mixed and stirred in the mixed solvent to a concentration of 1M to obtain an electrolyte solution according to Comparative Example B.

[0071] 7.1.3 Example A Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1 to obtain a mixed solvent. Lithium bis(fluorosulfonyl)amide (LiFSA) as a lithium amide salt and lithium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide (LiCFSA) were mixed and stirred in the mixed solvent in a molar ratio of 0.8:0.2 and a total concentration of 1M to obtain an electrolyte solution according to Example A.

[0072] 7.1.4 Example B Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1 to obtain a mixed solvent. Lithium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide (LiCFSA) as a lithium amide salt was mixed and stirred in the mixed solvent to a concentration of 1M to obtain an electrolyte solution according to Example B.

[0073] 7.1.5 Comparative Example C Ethylene carbonate (EC) and methyl propionate (MP) were mixed in a volume ratio of 15:85 to obtain a mixed solvent. Lithium bis(fluorosulfonyl)amide (LiFSA) as a lithium amide salt was mixed and stirred in the mixed solvent to a concentration of 1 M to obtain an electrolyte solution according to Comparative Example C.

[0074] 7.1.6 Example C Ethylene carbonate (EC) and methyl propionate (MP) were mixed in a volume ratio of 15:85 to obtain a mixed solvent. Lithium bis(fluorosulfonyl)amide (LiFSA) as a lithium amide salt and lithium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide (LiCFSA) were mixed and stirred in the mixed solvent in a molar ratio of 0.8:0.2 and a total concentration of 1M to obtain an electrolyte solution according to Example C.

[0075] 7.1.7 Example D Ethylene carbonate (EC) and methyl propionate (MP) were mixed in a volume ratio of 15:85 to obtain a mixed solvent. Lithium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide (LiCFSA) as a lithium amide salt was mixed and stirred in the mixed solvent to a concentration of 1M to obtain an electrolyte solution according to Example D.

[0076] 7.1.8 Example E Ethylene carbonate (EC) and methyl propionate (MP) were mixed in a volume ratio of 15:85 to obtain a mixed solvent. Lithium bis(fluorosulfonyl)amide (LiFSA) as a lithium amide salt and lithium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide (LiCFSA) were mixed and stirred in the mixed solvent in a molar ratio of 1.0:0.4 and a total concentration of 1.4M to obtain an electrolyte solution according to Example E.

[0077] 7.2 Aluminum corrosion evaluation A half cell was prepared using Al foil as the working electrode, Li metal as the counter electrode, and each of the electrolyte solutions according to the above-mentioned Examples A to E and Comparative Examples A to C, and the presence or absence of Al dissolution into the electrolyte solution (Al corrosivity) was evaluated by cyclic voltammetry (CV measurement). The specific measurement conditions were the same as those described above.

[0078] 7.3 Ionic conductivity evaluation A two-electrode symmetrical cell with fixed electrode area and electrode distance was prepared using Li metal for the electrodes and each of the electrolytes according to the above-mentioned Examples A to E and Comparative Examples A to C for the electrolyte, and the resistance value was measured by an AC impedance method at 25°C. The ionic conductivity was calculated from the obtained resistance value and the cell shape (electrode area, electrode distance). A two-electrode symmetrical cell with fixed electrode area and electrode distance was constructed, and the resistance value was measured by an AC impedance method at 25°. The ionic conductivity of the electrolyte was calculated from the obtained resistance value and the cell shape (electrode area and electrode distance). The impedance measurement conditions were the same as those described above.

[0079] 7.4 Evaluation Results Table 2 below shows the measurement results of the presence or absence of Al corrosion behavior and the ionic conductivity for each of the electrolyte solutions according to Examples A to E and Comparative Examples A to C.

[0080] [Table 2]

[0081] From the results shown in Table 2, it can be seen that the effect of inhibiting Al corrosion by adding LiCFSA to the electrolyte is exerted regardless of the type of organic solvent that constitutes the electrolyte. On the other hand, it can also be seen that the ionic conductivity of the electrolyte changes depending on the type of organic solvent. From the results shown in Table 2, it can be seen that when the electrolyte contains a carboxylate as an organic solvent, the ionic conductivity of the electrolyte is significantly improved. [Explanation of symbols]

[0082] 10 positive electrode 11 Cathode active material layer 12 Positive electrode current collector 20 negative electrode 21 Negative electrode active material layer 22 Negative electrode current collector 30 Electrolyte 40 Separator 50 Coating 100 Lithium-ion batteries

Claims

1. A lithium ion battery having a positive electrode, a negative electrode, and an electrolyte, The electrolyte solution is an organic solvent, and a lithium amide salt dissolved in said organic solvent; Including, The lithium amide salt includes LiCFSA represented by the following formula (1): one or both of the positive electrode and the negative electrode has an aluminum-containing current collector; the aluminum-containing current collector has a coating on a surface that comes into contact with the electrolyte, The coating is Al(CFSA) ｘ Including, Lithium-ion battery. 【Chemistry 1】

2. 2. The lithium ion battery of claim 1, The electrolytic solution contains sulfolane as the organic solvent; Lithium-ion battery.

3. 2. The lithium ion battery of claim 1, The electrolytic solution contains a carboxylic acid ester as the organic solvent. Lithium-ion battery.

4. 2. The lithium ion battery of claim 1, The coating comprises aluminum fluoride. Lithium-ion battery.

5. The lithium ion battery according to any one of claims 1 to 4, At least the positive electrode has the aluminum-containing current collector. Lithium-ion battery.

Images