A non-aqueous electrolyte and a battery

Abstract

To overcome the problem of poor high-temperature stability of the SEI film in existing lithium-ion batteries, the present invention provides a non-aqueous electrolyte, comprising a solvent, an electrolyte salt, and a compound shown in Structural Formula 1: wherein, A, G, and X are each independently selected from a cyclic sulfate group and its derivatives, a cyclic sulfonate group and its derivatives, a cyclic sulfite group and its derivatives, or Group D; and the number of Group D selected from A, G, and X is 0 or 1, and Group D is selected from an alkyl group with 1-4 carbon atoms, an unsaturated hydrocarbon group, a haloalkyl group, a nitrile group, an ether group, or a ketone group. The present invention also provides a battery comprising the above non-aqueous electrolyte. The non-aqueous electrolyte provided by the present invention uses the compound shown in Structural Formula 1 as an additive, which can effectively improve the film-forming quality on the surfaces of the positive and negative electrodes and improve the battery performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of secondary batteries, and particularly relates to a non-aqueous electrolyte and a battery. Background Art

[0002] During the charge and discharge process of a lithium-ion battery, chemical or electrochemical reactions will occur on the electrode surface to form a deposition film. On the negative electrode, it is called the SEI film, and on the positive electrode, it is often called the CEI film. In a graphite negative electrode, the SEI film is formed by the deposition of organic and inorganic decomposition products on the graphite surface during the reduction of the solvent and solute in the electrolyte. This film can maintain the kinetic stability of the electrolyte during subsequent charge and discharge processes, preventing the solvent and solute in the electrolyte from further decomposing. At the same time, the SEI film can prevent the solvent from embedding into the graphite layer and causing its peeling and decomposition, thereby improving the battery performance. However, the SEI film will have local losses during the charge and discharge processes. Therefore, an effective and stable SEI film has a crucial impact on the battery life and cycle performance, especially during high-rate and deep-discharge processes. The lithium-ion conductivity of the SEI film also has an important impact on the rate performance of the battery. High ionic conductivity can improve the rate performance and reduce the battery impedance. At the same time, the SEI film is very sensitive to temperature. Therefore, the high and low temperature performance of the battery is also closely related to the SEI film. More importantly, the SEI film also determines the safety performance of the battery. The CEI film has similar behaviors to the SEI film, and their compositions are very complex. Their thickness, composition, morphology, and compactness, etc., will all have a significant impact on the battery performance.

[0003] At present, the SEI film formed by additives, although it can improve the battery performance to a certain extent, still has disadvantages such as uneven thickness on the film surface and poor high-temperature stability, which have an adverse impact on the battery life and high-rate discharge. How to develop an additive that can further improve the quality of the SEI film is an urgent problem to be solved. Summary of the Invention

[0004] Aiming at the problem of poor high-temperature stability of the SEI film in existing lithium-ion batteries, the present invention provides a non-aqueous electrolyte and a battery.

[0005] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0006] On the one hand, the present invention provides a non-aqueous electrolyte, comprising a solvent, an electrolyte salt, and a compound shown in Structural Formula 1:

[0007]

[0008] Among them, A, G, and X are each independently selected from a cyclic sulfate group and its derivatives, a cyclic sulfonate group and its derivatives, a cyclic sulfite group and its derivatives, or group D; and the number of A, G, and X selected from group D is 0 or 1, and group D is selected from an alkyl group having 1 to 4 carbon atoms, an unsaturated hydrocarbon group, a haloalkyl group, a nitrile group, an ether group, or a ketone group.

[0009] Optionally, the cyclic sulfate group and its derivatives are selected from the groups shown in Structural Formula 2:

[0010]

[0011] Among them, * is the bonding position, R1 is selected from a single bond, an alkylene group having 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group, a, b, and c are natural numbers, and the sum of a, b, and c is any natural number from 0 to 5, R6, R7, and R8 are each independently selected from hydrogen, a halogen atom, or an alkyl group having 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is replaced by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or a halogen.

[0012] Optionally, the cyclic sulfonate group and its derivatives are selected from the groups shown in Structural Formula 3:

[0013]

[0014] Among them, * is the bonding position, R2 is selected from a single bond, an alkylene group having 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group, e, d, and f are natural numbers, and the sum of d, e, and f is any natural number from 0 to 5; R9, R 10 , R 11 are each independently selected from hydrogen, a halogen atom, or an alkyl group having 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is replaced by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or a halogen.

[0015] Optionally, the cyclic sulfite group and its derivatives are selected from the groups shown in Structural Formula 4:

[0016]

[0017] Among them, * is the bonding position, R4 is selected from a single bond, an alkylene group having 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group, g, h, and i are natural numbers, and the sum of g, h, and i is any natural number from 0 to 5; R 12 , R 13 , R 14Each independently selected from hydrogen, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is substituted by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or a halogen.

[0018] Optionally, the compound represented by Structural Formula 1 is selected from one or more of the following compounds:

[0019]

[0020]

[0021]

[0022]

[0023] Optionally, based on the total mass of the non-aqueous electrolyte being 100%, the addition amount of the compound represented by Structural Formula 1 is 0.001 to 10%.

[0024] Optionally, based on the total mass of the non-aqueous electrolyte being 100%, the addition amount of the compound represented by Structural Formula 1 is 0.1 to 3%.

[0025] Optionally, the lithium salt is selected from at least one of LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiBETI.

[0026] Optionally, the non-aqueous electrolyte further includes a functional additive, and the functional additive includes at least one of a cyclic sulfate compound, a sultone compound, a carbonate compound, an unsaturated phosphate compound, and a nitrile compound.

[0027] Optionally, the cyclic sulfate compound includes ethylene sulfate;

[0028] The sultone compound is selected from at least one of 1,3-propane sultone, 1,4-butane sultone, or 1,3-propene sultone;

[0029] The cyclic carbonate compound is selected from at least one of vinylene carbonate, ethylene vinylene carbonate, fluoroethylene carbonate, or the compound represented by Structural Formula 5,

[0030]

[0031] In Structural Formula 5, R 21 , R 22 , R23 , R 24 , R 25 , R 26 Each independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group;

[0032] The unsaturated phosphate compound is selected from at least one of the compounds shown in Structural Formula 6:

[0033]

[0034] In the Structural Formula 6, R 31 , R 32 , R 32 Each independently selected from a C1-C5 saturated hydrocarbon group, an unsaturated hydrocarbon group, a halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and at least one of R 31 , R 32 , R 33 is an unsaturated hydrocarbon group;

[0035] The nitrile compound includes one or more of succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexane trinitrile, adiponitrile, pimelonitrile, suberonitrile, azelaonitrile, and sebaconitrile.

[0036] The solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate.

[0037] On the other hand, the present invention provides a battery, including a positive electrode, a negative electrode, and the non-aqueous electrolyte as described above.

[0038] According to the non-aqueous electrolyte provided by the present invention, using the compound shown in Structural Formula 1 as an additive can play a greater improvement role in the film formation of the non-aqueous electrolyte on the positive and negative electrodes at a smaller addition amount. The passivation film formed by the compound shown in Structural Formula 1 has the advantages of high lithium ion conductivity and stability, improves the performance stability of the positive and negative electrode materials during long-term cycling, and extends the cycle life of the battery. At the same time, it is worth noting that compared with some existing conventional additives, the stability of this passivation film at high temperatures is particularly excellent. Therefore, using the non-aqueous electrolyte provided by the present invention, the obtained battery is particularly suitable for working under high temperature conditions, improving the environmental adaptability of the battery. Detailed Embodiments

[0039] In order to make the technical problems, technical solutions, and beneficial effects solved by the present invention clearer, the following further describes the present invention in detail with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] An embodiment of the present invention provides a non-aqueous electrolyte, comprising a solvent, an electrolyte salt, and a compound shown in Structural Formula 1:

[0041]

[0042] Wherein, A, G, and X are each independently selected from a cyclic sulfate group and its derivatives, a cyclic sulfonate group and its derivatives, a cyclic sulfite group and its derivatives, or group D; and the number of group D selected from A, G, and X is 0 or 1, and group D is selected from an alkyl group with 1-4 carbon atoms, an unsaturated hydrocarbon group, a haloalkyl group, a nitrile group, an ether group, or a ketone group.

[0043] Using the compound shown in Structural Formula 1 as an additive can greatly improve the film formation on the positive and negative electrodes of the non-aqueous electrolyte at a relatively small addition amount. The passivation film formed by the compound shown in Structural Formula 1 has the advantages of high lithium ion conductivity and stability, improving the performance stability of the positive and negative electrode materials during long-term cycling, and extending the cycle life of the battery. At the same time, it is worth noting that compared with some existing conventional additives, the stability of this passivation film at high temperatures is particularly excellent. Therefore, using the non-aqueous electrolyte provided by the present invention, the obtained battery is particularly suitable for working under high temperature conditions, improving the environmental adaptability of the battery.

[0044] Since the film formation mechanism on the positive and negative electrodes is relatively complex, the mechanism of the compound shown in Structural Formula 1 for improving the performance of the passivation film is not very clear. However, it can be understood that the central atom of the present invention is a boron atom, which is an electron-deficient center with empty orbitals and can interact with anions such as fluoride ions of inorganic lithium salts on the SEI or CEI film, thereby reducing the electrostatic interaction of the anions on the lithium ions, improving the lithium ion conductivity, reducing the overall impedance of the SEI or CEI, and thus improving the high-rate discharge efficiency; and the overall structure of the film formed by the compound shown in Structural Formula 1 is a cross-linked structure, with strong integrity after film formation, which is beneficial to reducing the solubility of the SEI film in the electrolyte, enhancing the high-temperature stability, and improving the battery life and cycling performance.

[0045] Examples of the above alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, etc.

[0046] Examples of the above unsaturated hydrocarbon group include vinyl, propenyl, butenyl, ethynyl, propynyl, butynyl, etc.

[0047] As the above haloalkyl group, at least one hydrogen atom in the above alkyl group is replaced by a halogen atom, and the halogen atom is selected from F, Cl, Br, I.

[0048] Examples of the nitrile group described above include cyanomethyl, cyanoethyl, cyanopropyl, cyanobutyl, etc.

[0049] As for the ether group described above, at least two adjacent carbon atoms in the above alkyl group are connected to each other by an oxygen atom.

[0050] As for the keto group described above, at least one carbon atom in the above alkyl group is connected to an oxygen atom by a double bond.

[0051] In some embodiments, the cyclic sulfate group and its derivatives are selected from the groups shown in Structural Formula 2:

[0052]

[0053] Wherein, * is the bonding position, R1 is selected from a single bond, an alkylene group with 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group, a, b, and c are natural numbers, and the sum of a, b, and c is any natural number from 0 to 5, R6, R7, and R8 are each independently selected from hydrogen, a halogen atom, an alkyl group with 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is replaced by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or halogen.

[0054] In the description of the present invention, examples of the heteroatom-containing group include nitrogen-containing groups such as amino, hydrazino, nitro, cyano, isocyano, and amidino groups; oxygen-containing groups such as alkanoyl, carboxyl, alkoxycarbonyl, hydroxyl, and alkoxy groups; sulfur-containing groups such as sulfo, sulfenyl, alkylsulfenyl, alkylsulfonyl, alkylsulfonylamino, alkylaminosulfonyl, alkylsulfinyl, alkylaminosulfinyl, alkylsulfinylamino, and thiocarboxyl groups; and halogen-containing groups such as fluorine atom, chlorine atom, bromine atom, and iodine atom.

[0055] In some embodiments, the cyclic sulfonate group and its derivatives are selected from the groups shown in Structural Formula 3:

[0056]

[0057] Wherein, * is the bonding position, R2 is selected from a single bond, an alkylene group with 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group, d, e, and f are natural numbers, and the sum of d, e, and f is any natural number from 0 to 5; R9, R 10 、R 11 are each independently selected from hydrogen, a halogen atom, an alkyl group with 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is replaced by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or halogen.

[0058] In some embodiments, the cyclic sulfite group and its derivatives are selected from the groups shown in Structural Formula 4:

[0059]

[0060] Among them, * is the bonding position, R4 is selected from a single bond, an alkylene group having 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is substituted by a heteroatom-containing group, g, h, and i are natural numbers, and the sum of g, h, and i is any natural number from 0 to 5; R 12 、R 13 、R 14 are each independently selected from hydrogen, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is substituted by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or halogen.

[0061] The present invention will be described below with specific compounds.

[0062] Compounds when A, G, and X are each independently selected from a cyclic sulfonate group and its derivatives or group D, and the number of group D is 0 or 1, including but not limited to the following structural formulas:

[0063]

[0064] Compounds when A, G, and X are each independently selected from a cyclic sulfate group and its derivatives or group D, and the number of group D is 0 or 1, including but not limited to the following structural formulas:

[0065]

[0066] Compounds when A, G, and X are each independently selected from a cyclic sulfite group and its derivatives or group D, and the number of group D is 0 or 1, including but not limited to the following structural formulas:

[0067]

[0068]

[0069] Compounds when A, G, and X are each independently selected from a cyclic sulfate group and its derivatives, a cyclic sulfite group and its derivatives, or group D, and the number of group D is 0 or 1, including but not limited to the following structural formulas:

[0070]

[0071] Compounds when A, G, and X are each independently selected from a cyclic sulfonate group and its derivatives, a cyclic sulfite group and its derivatives, or group D, and the number of group D is 0 or 1, including but not limited to the following structural formulas:

[0072]

[0073] When A, G, and X are respectively selected from cyclic sulfate groups and their derivatives, cyclic sulfonate groups and their derivatives, and cyclic sulfite groups and their derivatives, the compounds include, but are not limited to, the following structural formulas:

[0074]

[0075] The above compounds can be used alone or in combination of two or more.

[0076] Those skilled in the art can know the preparation methods of the above compounds based on the common general knowledge in the field of chemical synthesis when knowing the structural formulas of the compounds of Structural Formula 1. For example: The borate undergoes a transesterification reaction with the compounds shown in Structural Formulas I, II, and III to form the compound shown in Structural Formula 1. Or:

[0077] Boron trichloride undergoes a metathesis reaction with the compounds shown in Structural Formulas I, II, and III at low temperature to form the compound shown in Structural Formula 1.

[0078]

[0079] Among them, R1 is selected from a single bond, an alkylene group with 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group; a, b, and c are natural numbers, and the sum of a, b, and c is any natural number from 0 to 5; R6, R7, and R8 are each independently selected from hydrogen, a halogen atom, or an alkyl group with 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is replaced by a heteroatom-containing group, and the heteroatoms include one or more of O, N, S, or halogen.

[0080]

[0081] Among them, R2 is selected from a single bond, an alkylene group with 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group; e, d, and f are natural numbers, and the sum of e, d, and f is any natural number from 0 to 5; R9, R 10 、R 11 are each independently selected from hydrogen, a halogen atom, or an alkyl group with 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is replaced by a heteroatom-containing group, and the heteroatoms include one or more of O, N, S, or halogen.

[0082]

[0083] Among them, R4 is selected from a single bond, an alkylene group with 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group; g, h, and i are natural numbers, and the sum of g, h, and i is any natural number from 0 to 5; R12 , R 13 , R 14 Each independently selected from hydrogen, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is substituted with a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or a halogen.

[0084] In some embodiments, based on the total mass of the non-aqueous electrolyte being 100%, the addition amount of the compound represented by Structural Formula 1 is 0.001 to 10%.

[0085] In a preferred embodiment, based on the total mass of the non-aqueous electrolyte being 100%, the addition amount of the compound represented by Structural Formula 1 is 0.1 to 3%.

[0086] When the addition amount of the compound represented by Structural Formula 1 is within the above range, the battery impedance can be effectively reduced, and the cycle capacity retention rate and high-temperature cycle performance can be improved. If the addition amount of the compound represented by Structural Formula 1 is too small, it is difficult to produce an obvious improvement effect on the battery performance; if the addition amount of the compound represented by Structural Formula 1 is too large, it may affect the function of other substances in the electrolyte due to too many decomposition products.

[0087] In some embodiments, the electrolyte salt includes one or more of a lithium salt, a sodium salt, a potassium salt, a magnesium salt, a zinc salt, and an aluminum salt. In a preferred embodiment, the electrolyte salt is selected from lithium salts.

[0088] In a more preferred embodiment, the electrolyte salt is at least one of LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiBETI.

[0089] In some embodiments, in the non-aqueous electrolyte, the concentration of the electrolyte salt is 0.1 mol / L - 8 mol / L. In a preferred embodiment, in the non-aqueous electrolyte, the concentration of the electrolyte salt is 0.5 mol / L - 2.5 mol / L.

[0090] In some embodiments, the non-aqueous electrolyte further includes a functional additive, and the functional additive includes at least one of a cyclic sulfate compound, a sultone compound, a carbonate compound, an unsaturated phosphate compound, and a nitrile compound.

[0091] In some embodiments, the cyclic sulfate compound includes ethylene sulfate;

[0092] The sulfonic acid lactone compounds are selected from at least one of 1,3 - propane sultone, 1,4 - butane sultone or 1,3 - propene sultone;

[0093] The cyclic carbonate compounds are selected from at least one of vinylene carbonate, ethylene vinylene carbonate, fluoroethylene carbonate or the compound shown in Structural Formula 5,

[0094]

[0095] In the Structural Formula 5, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 each independently is selected from one of a hydrogen atom, a halogen atom, and a C1 - C5 group;

[0096] The unsaturated phosphate compounds are selected from at least one of the compounds shown in Structural Formula 6:

[0097]

[0098] In the Structural Formula 6, R 31 , R 32 , R 32 each independently is selected from a C1 - C5 saturated hydrocarbon group, an unsaturated hydrocarbon group, a halogenated hydrocarbon group, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and at least one of R 31 , R 32 , R 33 is an unsaturated hydrocarbon group.

[0099] In a preferred embodiment, the unsaturated phosphate compounds can be at least one of tri - propargyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl - 2,2,2 - trifluoroethyl phosphate, diallyl - 3,3,3 - trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate, tri - allyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl - 2,2,2 - trifluoroethyl phosphate, diallyl - 3,3,3 - trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate.

[0100] The nitrile compounds include one or more of succinonitrile, glutarodinitrile, ethylene glycol bis(propionitrile) ether, hexane trinitrile, adiponitrile, pimelonitrile, suberonitrile, azelaonitrile, sebaconitrile.

[0101] In a preferred embodiment, based on the total mass of the non-aqueous electrolyte being 100%, the addition amount of the functional additive is 0.001 to 10%.

[0102] In the non-aqueous electrolyte, when the compound shown in Structural Formula 1 is added together with the existing functional additives as compared to single addition or a combination of other existing additives, it shows an obvious synergistic improvement effect in enhancing the high-temperature cycle performance of the battery, indicating that the compound shown in Structural Formula 1 and the existing functional additives form a film together on the electrode surface, which can make up for the film-forming defects of single addition and obtain a more stable passivation film.

[0103] In some embodiments, the solvent includes one or more of an ether solvent, a nitrile solvent, a carbonate solvent, and a carboxylate solvent.

[0104] In some embodiments, the ether solvent includes a cyclic ether or a linear ether. The cyclic ether can specifically but not limited to be one or more of 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), 2-trifluoromethyltetrahydrofuran (2-CF3-THF); the linear ether can specifically but not limited to be one or more of dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (TEGDME). The nitrile solvent can specifically but not limited to be one or more of acetonitrile, glutaronitrile, and malononitrile. The carbonate solvent includes a cyclic carbonate or a linear carbonate. The cyclic carbonate can specifically but not limited to be one or more of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and butylene carbonate (BC); the linear carbonate can specifically but not limited to be one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dipropyl carbonate (DPC). The carboxylate solvent can specifically but not limited to be one or more of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate.

[0105] Another embodiment of the present invention provides a battery, including a positive electrode, a negative electrode, and the non-aqueous electrolyte as described above.

[0106] Since the battery adopts the non-aqueous electrolyte as described above, it can form a passivation film with excellent performance on the positive electrode and the negative electrode, thereby effectively improving the high-temperature storage performance and high-temperature cycle performance of the battery and enhancing the battery power characteristics.

[0107] In some embodiments, the battery is a secondary battery, and the secondary battery can be a lithium secondary battery, a potassium secondary battery, a sodium secondary battery, a magnesium secondary battery, a zinc secondary battery, an aluminum secondary battery, etc.

[0108] In a preferred embodiment, the battery is a lithium metal battery, a lithium ion battery or a lithium sulfur battery.

[0109] In some embodiments, the positive electrode includes a positive electrode active material. There is no particular limitation on the type of the positive electrode active material, as long as it is a positive electrode active material or a conversion type positive electrode material that can reversibly intercalate / deintercalate metal ions (such as lithium ions, sodium ions, potassium ions, magnesium ions, zinc ions, aluminum ions, etc.). Preferably, the positive electrode active material is selected from at least one of nickel cobalt manganese ternary materials, LiFePO4, LiCoO2, sulfur and its composites.

[0110] In some embodiments, the negative electrode includes a negative electrode active material, and the negative electrode active material includes one or more of a carbon-based negative electrode, a tin-based negative electrode, a lithium negative electrode, a sodium negative electrode, a potassium negative electrode, a magnesium negative electrode, a zinc negative electrode and an aluminum negative electrode. Among them, the carbon-based negative electrode may include graphite, hard carbon, soft carbon, graphene, mesophase carbon microspheres, etc.; the tin-based negative electrode may include tin, tin carbon, tin oxygen, tin metal compounds; the lithium negative electrode may include metallic lithium or a lithium alloy. The lithium alloy may specifically be at least one of a lithium-silicon alloy, a lithium-sodium alloy, a lithium-potassium alloy, a lithium-aluminum alloy, a lithium-tin alloy and a lithium-indium alloy.

[0111] In some embodiments, the battery further includes a separator, and the separator is located between the positive electrode and the negative electrode.

[0112] The separator may be a conventional existing separator, which may be a polymer separator, a non-woven fabric, etc., including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP, and three-layer PP / PE / PP separators.

[0113] The present invention is further illustrated by the following examples.

[0114] Table 1

[0115]

[0116]

[0117] Note: Compounds 1-6 used in the following examples and comparative examples are selected from Table 1.

[0118] Examples 1-13

[0119] This example is used to illustrate the preparation method of the non-aqueous electrolyte and the battery disclosed in the present invention, and includes the following operation steps:

[0120] 1) Preparation of the non-aqueous electrolyte:

[0121] Ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) were mixed at a mass ratio of EC:DEC:EMC = 1:1:1, and then lithium hexafluorophosphate (LiPF6) was added to a molar concentration of 1 mol / L. Based on the total weight of the non-aqueous electrolyte being 100%, additives with the mass percentages shown in Examples 1 to 13 of Table 2 were added.

[0122] 2) Preparation of the positive electrode plate:

[0123] The positive electrode active material lithium nickel cobalt manganese oxide LiNi 0.5 Co 0.2 Mn 0.3 O2, conductive carbon black Super-P, and binder polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 93:4:3, and then they were dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. The slurry was evenly coated on both sides of an aluminum foil, dried, calendered, and vacuum dried, and then an aluminum lead wire was welded with an ultrasonic welder to obtain a positive electrode plate, and the thickness of the plate was between 120 - 150 μm.

[0124] 3) Preparation of the negative electrode plate:

[0125] The negative electrode active material artificial graphite, conductive carbon black Super-P, binder styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed at a mass ratio of 94:1:2.5:2.5, and then they were dispersed in deionized water to obtain a negative electrode slurry. The slurry was coated on both sides of a copper foil, dried, calendered, and vacuum dried, and then a nickel lead wire was welded with an ultrasonic welder to obtain a negative electrode plate, and the thickness of the plate was between 120 - 150 μm.

[0126] 4) Preparation of the battery cell:

[0127] A three-layer separator with a thickness of 20 μm was placed between the positive electrode plate and the negative electrode plate, and then the sandwich structure composed of the positive electrode plate, the negative electrode plate, and the separator was wound. After the wound body was flattened, it was placed in an aluminum foil packaging bag and vacuum baked at 75°C for 48 h to obtain a battery cell to be filled with electrolyte.

[0128] 5) Filling and formation of the battery cell:

[0129] In a glove box with the dew point controlled below -40°C, the electrolyte prepared above was injected into the battery cell, vacuum packaged, and left to stand for 24 h.

[0130] Then, the first charge normalization is carried out according to the following steps: constant current charging at 0.05C for 180 min, constant current charging at 0.2C until 3.95V, secondary vacuum sealing, and then further constant current charging at 0.2C until 4.2V. After standing at room temperature for 24 hr, constant current discharging at 0.2C until 3.0V to obtain a LiNi 0.5 Co 0.2 Mn 0.3 O2 / artificial graphite lithium-ion battery.

[0131] Comparative Examples 1-5

[0132] This example is used to compare and illustrate the method of the non-aqueous electrolyte and battery disclosed in the present invention, including most of the operation steps in Example 1. The difference is that:

[0133] In the preparation of the non-aqueous electrolyte, additives with the mass percentage shown in Comparative Examples 1-5 in Table 2 are added.

[0134] Performance test

[0135] The following performance tests are carried out on the lithium-ion batteries prepared in Examples 1-13 and Comparative Examples 1-5: high-temperature cycle performance test

[0136] The prepared lithium-ion battery is placed in an oven at a constant temperature of 45°C, constant current charged at 1C until 4.2V, then constant current and constant voltage charged until the current drops to 0.05C, and then constant current discharged at 1C until 3.0V. Such a cycle is carried out, and the discharge capacity of the first time and the last time are recorded.

[0137] The capacity retention rate of the high-temperature cycle is calculated according to the following formula:

[0138] Capacity retention rate = the discharge capacity of the last time / the discharge capacity of the first time × 100%.

[0139] The test results are filled in Table 2.

[0140] Table 2

[0141]

[0142]

[0143] Comparing the test results of Examples 1-6 and Comparative Examples 1-4, it can be seen that compared with traditional vinylene carbonate (VC), divinyl sulfite (DTD), and 1,3-propane sultone (PS), using the compound shown in Structural Formula 1 provided in this application as an additive can more significantly improve the cycle of lithium-ion batteries at high temperature, indicating that the passivation film formed by the compound shown in Structural Formula 1 has more excellent high-temperature stability.

[0144] By comparing the test results of Example 1 and Examples 7 to 11, it can be seen that as the addition amount of the compound represented by Structural Formula 1 increases, the high temperature cycle performance of the lithium ion battery first increases and then decreases. In particular, when the addition amount of the compound represented by Structural Formula 1 is between 0.5% and 2%, the lithium ion battery has the best high temperature cycle performance.

[0145] From the test results of Comparative Example 12 and Comparative Example 5, it can be seen that compared with the traditional combination additives of vinylene carbonate (VC) and vinyl sulfate (DTD), the combination of the compound shown in Structural Formula 1 provided in the present application and vinyl sulfate (DTD) further improves the passivation film formed by the compound shown in Structural Formula 1 and has better high-temperature stability.

[0146] By comparing the test results of Example 13 and Example 1, it can be seen that compared with the single addition of the compound shown in Structural Formula 1, the combination of the compound shown in Structural Formula 1 and vinylene carbonate (VC) has a more obvious improvement in the high-temperature cycle performance of the battery, indicating that the passivation film formed by the compound shown in Structural Formula 1 and vinylene carbonate (VC) has good high-temperature stability.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-aqueous electrolyte, characterized in that, Comprising a solvent, an electrolyte salt, and a compound represented by Structural Formula 1: Structural Formula 1 Wherein, A, G, and X are each independently selected from a cyclic sulfate group and its derivatives, a cyclic sulfonate group and its derivatives, a cyclic sulfite group and its derivatives, or Group D; and the number of those selected from Group D among A, G, and X is 0 or 1, and Group D is selected from an alkyl group having 1 to 4 carbon atoms, an unsaturated hydrocarbon group, a haloalkyl group, a nitrile group, an ether group, or a ketone group.

2. The non-aqueous electrolyte according to claim 1, characterized in that, The cyclic sulfate group and its derivatives are selected from the groups represented by Structural Formula 2: Structural Formula 2 Wherein, * is the bonding position, R1 is selected from a single bond, an alkylene group having 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is substituted by a heteroatom-containing group, a, b, and c are natural numbers, and the sum of a, b, and c is any natural number from 0 to 5, R6, R7, and R8 are each independently selected from hydrogen, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is substituted by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or a halogen.

3. The non-aqueous electrolyte according to claim 1, characterized in that, The cyclic sulfonate group and its derivatives are selected from the groups represented by Structural Formula 3: Structural Formula 3 Among them, * is the bonding position, R2 is selected from a single bond, an alkylene group with 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is replaced by a heteroatom-containing group, e, d, and f are natural numbers, and the sum of d, e, and f is any natural number from 0 to 5; R9, R 10 , R 11 are each independently selected from hydrogen, a halogen atom, an alkyl group with 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is replaced by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or a halogen.

4. The non-aqueous electrolyte according to claim 1, characterized in that, The cyclic sulfite group and its derivatives are selected from the groups represented by Structural Formula 4: Structural Formula 4 Among them, * is the bonding position, R4 is selected from a single bond, an alkylene group having 1 to 4 carbon atoms, and a group in which at least one hydrogen atom in the alkylene group is substituted by a heteroatom-containing group, g, h, and i are natural numbers, and the sum of g, h, and i is any natural number from 0 to 5; R 12 , R 13 , R 14 are each independently selected from hydrogen, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and a group in which at least one hydrogen atom in the alkyl group is substituted by a heteroatom-containing group, and the heteroatom includes one or more of O, N, S, or halogen.

5. The non-aqueous electrolyte according to claim 1, characterized in that, The compound represented by Structural Formula 1 is selected from one or more of the following compounds: 。 6. The non-aqueous electrolyte according to claim 1, characterized in that, Based on the total mass of the non-aqueous electrolyte being 100%, the addition amount of the compound represented by Structural Formula 1 is 0.001 to 10%.

7. The non-aqueous electrolyte according to claim 1, characterized in that, Based on the total mass of the non-aqueous electrolyte being 100%, the addition amount of the compound represented by Structural Formula 1 is 0.1 to 3%.

8. The non-aqueous electrolyte according to claim 1, wherein The electrolyte salt is selected from lithium salts, and the lithium salts are selected from at least one of LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiBETI.

9. The non-aqueous electrolyte according to claim 1, characterized in that, The non-aqueous electrolyte further includes a functional additive, and the functional additive includes at least one of a cyclic sulfate compound, a sultone compound, a cyclic carbonate compound, an unsaturated phosphate compound, and a nitrile compound.

10. The non-aqueous electrolyte according to claim 9, characterized in that, The cyclic sulfate compound includes ethylene sulfate; The sultone compound is selected from at least one of 1,3-propane sultone, 1,4-butane sultone, or 1,3-propene sultone; The cyclic carbonate compound is selected from at least one of vinylene carbonate, ethylene vinylene carbonate, fluoroethylene carbonate, or the compound represented by Structural Formula 5, Structural Formula 5 In the said structural formula 5, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 are each independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group; The unsaturated phosphate compound is selected from at least one of the compounds represented by Structural Formula 6: Structural Formula 6 In the said structural formula 6, R 31 , R 32 , R 32 are each independently selected from saturated hydrocarbon groups, unsaturated hydrocarbon groups, halogenated hydrocarbon groups, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and at least one of R 31 , R 32 , R 33 is an unsaturated hydrocarbon group; The nitrile compound includes one or more of succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexane trinitrile, adiponitrile, pimelonitrile, suberonitrile, azelaonitrile, sebaconitrile.

11. The non-aqueous electrolyte according to claim 1, characterized in that, The solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate.

12. A battery, characterized in that, It includes a positive electrode, a negative electrode, and a non-aqueous electrolyte as described in any one of claims 1 to 11.

Images