Non-aqueous electrolyte and battery

Abstract

In order to overcome the problems of uneven thickness, poor high-temperature stability, low lithium ion conductivity and high impedance of the existing electrode surface passivation film, the application provides a non-aqueous electrolyte, which comprises at least one compound shown in structural formula 1: wherein n is a natural number of 0-4, A is selected from a cyclic sulfate group and its derivative, a cyclic sulfonate group and its derivative, a cyclic carbonate group and its derivative, or a cyclic sulfite group and its derivative. Meanwhile, the application also discloses a lithium ion battery comprising the non-aqueous electrolyte. The non-aqueous electrolyte provided by the application can occur electrochemical reaction on the electrode surface, and can form a relatively stable film structure by moderate cross-linking, thereby being beneficial to improving the quality of the electrode surface passivation film.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a non-aqueous electrolyte and battery. Background Technology

[0002] Lithium-ion batteries have been widely used in 3C digital products such as mobile phones and laptops, as well as new energy vehicles, due to their advantages such as high operating voltage, wide operating temperature range, high energy density and power density, no memory effect and long cycle life.

[0003] Current research indicates that during the formation and charge-discharge cycling of lithium-ion batteries, substances in the electrolyte decompose on the surface of the negative electrode to form an SEI film, while a CEI film is correspondingly formed on the surface of the positive electrode. The quality of the SEI and CEI film formation has a significant impact on various electrochemical performance characteristics of lithium-ion batteries. Adding additives to the electrolyte of lithium-ion batteries to improve the stability of SEI and CEI film formation, thereby enhancing the battery's cycle stability, is a common practice. However, the SEI and CEI films formed by additives still suffer from drawbacks such as uneven film thickness, poor high-temperature stability, low lithium-ion conductivity, and high impedance, all of which negatively affect battery life and high-rate discharge performance. Summary of the Invention

[0004] To address the problems of uneven thickness, poor high-temperature stability, low lithium-ion conductivity, and high impedance of existing electrode surface passivation films, this invention provides a non-aqueous electrolyte and battery.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] On one hand, the present invention provides a non-aqueous electrolyte comprising at least one of the compounds shown in structural formula 1:

[0007]

[0008]

[0009] Where n is a natural number from 0 to 4, and A is selected from cyclic sulfate groups and their derivatives, cyclic sulfonate groups and their derivatives, cyclic carbonate groups and their derivatives, or cyclic sulfite groups and their derivatives.

[0010] Optionally, the cyclic sulfate group and its derivatives are selected from groups shown in structural formula 2:

[0011]

[0012] Wherein, * represents the bonding position, a, b, and c are natural numbers, and the sum of a, b, and c is 0 or 1. R1, R2, and R3 are each independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens.

[0013] Optionally, the cyclic sulfonate group and its derivatives are selected from the groups shown in structural formula 3:

[0014]

[0015] Wherein, * represents the bonding position, d, e, and f are natural numbers, and the sum of d, e, and f is 0, 1, or 2. R4, R5, and R6 are each independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens.

[0016] Optionally, the cyclic carbonate group and its derivatives are selected from the groups shown in structural formula 4:

[0017]

[0018] Wherein, * represents the bonding position, l, o, and p are natural numbers, and the sum of l, o, and p is 0 or 1. R7, R8, and R9 are each independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens.

[0019] Optionally, the cyclic sulfite group and its derivatives are selected from the groups shown in structural formula 5:

[0020]

[0021] Where * represents the bonding position, g, h, and i are natural numbers, and the sum of g, h, and i is 0 or 1, R 10 R 11 R 12 Each of the following is independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens.

[0022] Optionally, the compound represented by structural formula 1 is selected from one or more of the following compounds:

[0023]

[0024]

[0025] Optionally, based on the total mass of the non-aqueous electrolyte as 100%, the amount of the compound represented by structural formula 1 added is 0.01 to 10%.

[0026] Optionally, the non-aqueous electrolyte further includes an electrolyte salt selected from LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiClO4, LiAlCl4, LiCF3SO3, and Li2B. 10 Cl 10 At least one of the following: lithium salts of lower aliphatic carboxylic acids.

[0027] Optionally, the non-aqueous electrolyte further includes auxiliary additives, which include at least one of cyclic sulfate compounds, sulfonyl lactone compounds, cyclic carbonate compounds, unsaturated phosphate compounds, and nitrile compounds.

[0028] Preferably, the cyclic sulfate compound is selected from at least one of vinyl sulfate, propylene sulfate, or methyl vinyl sulfate;

[0029] The sulfonyl lactone compound is selected from at least one of 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, or 1,3-propenesulfonyl lactone.

[0030] The cyclic carbonate compound is selected from at least one of vinylene carbonate, ethylene ethylene carbonate, fluoroethylene carbonate, or the compound shown in structural formula 6.

[0031]

[0032] In structural formula 6, R 21 R 22 R 23 R 24 R 25 R 26 Each is independently selected from one of the following: hydrogen atom, halogen atom, or C1-C5 group;

[0033] The unsaturated phosphate compound is selected from at least one of the compounds shown in structural formula 7:

[0034]

[0035] In structural formula 7, R 31R 32 R 32 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group;

[0036] The nitrile compounds include one or more of the following: succinic acid, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptacyanide, octadionitrile, nonadionitrile, and sebaconitol.

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

[0038] The non-aqueous electrolyte provided by this invention uses a compound represented by structural formula 1 as an additive, which can undergo an electrochemical reaction on the electrode surface and simultaneously form a relatively stable thin film structure through moderate cross-linking. Specifically, the central atom of the compound represented by structural formula 1 is a silicon atom, which has a good affinity for lithium. Its silicon-oxygen bonds connect multiple cyclic structures A. When one of the cyclic structures A of the compound represented by structural formula 1 undergoes an electrochemical reaction on the electrode surface to form a lithium salt, the remaining cyclic structures A are closely close to the electrode sheet due to the affinity between silicon and lithium, making it easier for them to undergo an electrochemical reaction on the electrode surface to form a lithium salt. This results in the formation of an SEI film or CEI film with strong integrity, uniform film thickness, and good lithium-ion permeability, thereby improving the high-temperature performance of the battery and enhancing its lifespan. Detailed Implementation

[0039] To make the technical problems solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the present invention.

[0040] This invention provides a non-aqueous electrolyte comprising at least one of a solvent, an electrolyte salt, and a compound represented by structural formula 1:

[0041]

[0042] Where n is a natural number from 0 to 4, and A is selected from cyclic sulfate groups and their derivatives, cyclic sulfonate groups and their derivatives, cyclic carbonate groups and their derivatives, or cyclic sulfite groups and their derivatives.

[0043] The inventors, through research and speculation, believe that the addition of the compound shown in Structural Formula 1 to the non-aqueous electrolyte allows the compound to undergo an electrochemical reaction on the electrode surface and simultaneously cross-link to form a relatively stable thin film structure. Specifically, the central atom of the compound shown in Structural Formula 1 is a silicon atom, which has a good affinity for lithium. Its silicon-oxygen bonds connect multiple cyclic structures A. When one of the cyclic structures A of the compound shown in Structural Formula 1 undergoes an electrochemical reaction on the electrode surface to form a lithium salt, the remaining cyclic structures A, due to the affinity between silicon and lithium, are closely close to the electrode sheet and are more likely to undergo an electrochemical reaction on the electrode surface to form a lithium salt. This results in the formation of a highly intact, uniformly thick, and lithium-ion permeable SEI or CEI film, thereby improving the battery's high-temperature performance and extending its lifespan.

[0044] In some embodiments, the cyclic sulfate group and its derivatives are selected from groups as shown in structural formula 2:

[0045]

[0046] Wherein, * represents the bonding position, a, b, and c are natural numbers, and the sum of a, b, and c is 0 or 1. R1, R2, and R3 are each independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens.

[0047] In some embodiments, the cyclic sulfonate group and its derivatives are selected from the groups shown in structural formula 3:

[0048]

[0049] Wherein, * represents the bonding position, d, e, and f are natural numbers, and the sum of d, e, and f is 0, 1, or 2. R4, R5, and R6 are each independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens.

[0050] In some embodiments, the cyclic carbonate groups and their derivatives are selected from the groups shown in structural formula 4:

[0051]

[0052] Wherein, * represents the bonding position, l, o, and p are natural numbers, and the sum of l, o, and p is 0 or 1. R7, R8, and R9 are each independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens.

[0053] In some embodiments, the cyclic sulfite group and its derivatives are selected from the groups shown in structural formula 5:

[0054]

[0055] Where * represents the bonding position, g, h, and i are natural numbers, and the sum of g, h, and i is 0 or 1, R 10 R 11 R 12 Each of the following is independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens.

[0056] In the description of this invention, the alkyl groups mentioned above can be exemplified by: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, etc.

[0057] Examples of halogen atoms mentioned above include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms being preferred.

[0058] Examples of heteroatom-containing groups mentioned above include: nitrogen-containing groups such as amino, hydrazine, nitro, cyano, isocyano, and amidine; oxygen-containing groups such as alkyl acyl, carboxyl, alkoxycarbonyl, hydroxyl, and alkoxy; sulfur-containing groups such as sulfonyl, oxythio, alkyloxythio, alkylsulfonyl, alkylsulfonylamino, alkylaminosulfonyl, alkylsulfinyl, alkylaminosulfinyl, alkylsulfinylamino, and thiocarboxyl; and halogen-containing groups such as fluorine, chlorine, bromine, and iodine atoms.

[0059] The compounds represented by structural formula 1 provided by this invention will be described below using specific examples:

[0060] When A is selected from the group shown in structural formula 4, the compound shown in structural formula 1 includes, but is not limited to, the following compounds:

[0061]

[0062] When A is selected from the group shown in structural formula 5, the compound shown in structural formula 1 includes, but is not limited to, the following compounds:

[0063]

[0064] When A is selected from the group shown in structural formula 2, the compound shown in structural formula 1 includes, but is not limited to, the following compounds:

[0065]

[0066] When A is selected from the group shown in structural formula 3, the compound shown in structural formula 1 includes, but is not limited to, the following compounds:

[0067]

[0068] The above compounds can be used alone or in combination of two or more.

[0069] Those skilled in the art, knowing the structural formula of the compound of formula 1, can understand the preparation method of the above-mentioned compound based on common knowledge in the field of chemical synthesis. For example, the compound of formula 1 can be prepared by the following method:

[0070] Silicon tetrachloride is reacted with the compound shown in structural formula 8 to undergo a metathesis reaction, producing the compound shown in structural formula 1.

[0071] HO-(CH2) n -A

[0072] Structural Formula 8

[0073] Where n = 0-4, and A is selected from cyclic sulfate groups and their derivatives, cyclic sulfonate groups and their derivatives, cyclic carbonate groups and their derivatives, or cyclic sulfite groups and their derivatives.

[0074] In some embodiments, the amount of compound represented by structural formula 1 added is 0.01 to 10% based on the total mass of the non-aqueous electrolyte being 100%.

[0075] In a preferred embodiment, the amount of the compound represented by structural formula 1 added is 0.1-5% based on the total mass of the non-aqueous electrolyte being 100%.

[0076] Specifically, the mass percentage of the compound represented by structural formula 1 can be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0077] When the amount of compound shown in structural formula 1 is within the above range, it can effectively maintain the stability of the film formed on the electrode surface and improve the battery performance. If the amount of compound shown in structural formula 1 is too small, it will be difficult to significantly improve the battery performance. If the amount of compound shown in structural formula 1 is too large, it may affect the function of other substances in the electrolyte due to the excessive decomposition products.

[0078] In some embodiments, the non-aqueous electrolyte further includes an electrolyte salt, which includes one or more of lithium, sodium, potassium, magnesium, zinc, and aluminum salts. In a preferred embodiment, the electrolyte salt is selected from lithium or sodium salts.

[0079] In a preferred embodiment, the electrolyte salt is selected from LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiClO4, LiAlCl4, LiCF3SO3, and Li2B. 10 Cl 10 At least one of the following: lower aliphatic carboxylic acid lithium salts. If the electrolyte salt is selected from other salts such as sodium salts, potassium salts, magnesium salts, zinc salts, or aluminum salts, the lithium in the above lithium salt can be replaced with sodium, potassium, magnesium, zinc, or aluminum, etc.

[0080] In a preferred embodiment, the sodium salt is selected from at least one of sodium perchlorate (NaClO4), sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium trifluoromethanesulfonate (NaFSI), and sodium bis(trifluoromethanesulfonate) (NaTFSI).

[0081] In some embodiments, the concentration of the electrolyte salt in the non-aqueous electrolyte is 0.1 mol / L to 8 mol / L. In a preferred embodiment, the concentration of the electrolyte salt in the non-aqueous electrolyte is 0.5 mol / L to 2.5 mol / L. Specifically, the concentration of the electrolyte salt can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, or 2.5 mol / L.

[0082] In some embodiments, the non-aqueous electrolyte further includes auxiliary additives, which include at least one of cyclic sulfate compounds, sulfonyl lactone compounds, cyclic carbonate compounds, unsaturated phosphate compounds, and nitrile compounds.

[0083] Preferably, the cyclic sulfate compound is selected from at least one of vinyl sulfate, propylene sulfate, or methyl vinyl sulfate;

[0084] The sulfonyl lactone compound is selected from at least one of 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, or 1,3-propenesulfonyl lactone.

[0085] The cyclic carbonate compound is selected from at least one of vinylene carbonate, ethylene ethylene carbonate, fluoroethylene carbonate, or the compound shown in structural formula 6.

[0086]

[0087] In structural formula 6, R 21 R 22 R 23 R 24 R 25 R 26 Each is independently selected from one of the following: hydrogen atom, halogen atom, or C1-C5 group.

[0088] The unsaturated phosphate compound is selected from at least one of the compounds shown in structural formula 7:

[0089]

[0090] In structural formula 7, R 31 R 32 R 32 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group. Specifically, the unsaturated phosphate ester compound may be at least one of the following: triargyl 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, triallyl 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, and diallyl hexafluoroisopropyl phosphate.

[0091] The nitrile compounds include one or more of the following: succinic acid, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptacyanide, octadionitrile, nonadionitrile, and sebaconitol.

[0092] It should be noted that, unless otherwise specified, the amount of any one of the optional substances in the auxiliary additives added to the non-aqueous electrolyte is generally less than 10%, preferably 0.1-5%, and more preferably 0.1% to 2%. Specifically, the amount of any one of the optional substances in the auxiliary additives can be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0093] In some embodiments, when the auxiliary additive is selected from fluoroethylene carbonate, the amount of fluoroethylene carbonate added is 0.05% to 30% based on 100% of the total mass of the non-aqueous electrolyte.

[0094] In the non-aqueous electrolyte, compared with single addition or combination of other existing additives, the compound shown in structural formula 1, when added together with the auxiliary additive, exhibits a significant synergistic effect in improving battery performance. This indicates that the compound shown in structural formula 1 and existing auxiliary additives can form a film together on the electrode surface to compensate for the film formation defects of single addition, resulting in a more stable passivation film.

[0095] In some embodiments, the non-aqueous electrolyte further includes a solvent, which includes one or more of ether solvents, nitrile solvents, carbonate solvents, carboxylic acid ester solvents, and sulfone solvents.

[0096] In some embodiments, the ether solvent includes cyclic ethers or chain ethers, preferably chain ethers with 3 to 10 carbon atoms and cyclic ethers with 3 to 6 carbon atoms. The cyclic ethers may be, but are not limited to, one or more of 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ethers, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), and 2-trifluoromethyltetrahydrofuran (2-CF3-THF). The chain ethers may be, but are not limited to, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether. Because chain ethers have high solvation ability with lithium ions and can improve ion dissociation, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane, which have low viscosity and can impart high ionic conductivity, are particularly preferred. Ether compounds can be used alone or in any combination and ratio of two or more. There are no particular restrictions on the amount of ether compounds added; it is arbitrary as long as it does not significantly impair the performance of the high-pressure lithium-ion battery of this invention. Typically, the volume ratio is 1% or more, preferably 2% or more, and more preferably 3% or more when the non-aqueous solvent volume ratio is 100%. Furthermore, the volume ratio is typically 30% or less, preferably 25% or less, and more preferably 20% or less. When using two or more ether compounds in combination, the total amount of ether compounds should meet the above-mentioned range. When the amount of ether compounds added is within the above-mentioned preferred range, it is easy to ensure the improved ionic conductivity resulting from the increased lithium-ion dissociation degree and reduced viscosity of the chain ethers. Additionally, when the negative electrode active material is a carbon material, the phenomenon of co-intercalation between the chain ethers and lithium ions can be suppressed, thus enabling the input / output characteristics and charge / discharge rate characteristics to reach an appropriate range.

[0097] In some embodiments, the nitrile solvent may be, but is not limited to, one or more of acetonitrile, glutaronitrile, and malononitrile.

[0098] In some embodiments, the carbonate solvent includes cyclic carbonates or chain carbonates. Cyclic carbonates may specifically be, but are not limited to, one or more of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and butylene carbonate (BC); chain carbonates may specifically be, but are not limited to, one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dipropyl carbonate (DPC). The content of cyclic carbonates is not particularly limited and is arbitrary within a range that does not significantly impair the performance of the high-pressure lithium-ion battery of this invention. However, when using a single type, its lower limit relative to the total volume of the non-aqueous electrolyte solvent is typically 3% or more, preferably 5% or more. By setting this range, a decrease in conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte can be avoided, making it easier to achieve good high-current discharge characteristics, stability relative to the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery. Furthermore, the upper limit is typically 90% or less, preferably 85% or less, and more preferably 80% or less. By setting this range, the oxidation / reduction resistance of the non-aqueous electrolyte can be improved, thereby contributing to enhanced stability during high-temperature storage. The content of the chain carbonate is not particularly limited, but relative to the total amount of solvent in the non-aqueous electrolyte, it is typically 15% or more by volume, preferably 20% or more, and more preferably 25% or more. Furthermore, it is typically 90% or less by volume, preferably 85% or less, and more preferably 80% or less. By keeping the chain carbonate content within the above range, it is easier to achieve an appropriate viscosity for the non-aqueous electrolyte, suppressing the decrease in ionic conductivity, and thus contributing to achieving a favorable range of output characteristics for the non-aqueous electrolyte battery. When using two or more chain carbonates in combination, it is sufficient to ensure that the total amount of chain carbonate meets the above range.

[0099] In some embodiments, fluorine-containing chain carbonates (hereinafter referred to as "fluorinated chain carbonates") are also preferably used. There is no particular limitation on the number of fluorine atoms in a fluorinated chain carbonate as long as it is 1 or more, but it is generally 6 or less, preferably 4 or less. When a fluorinated chain carbonate has multiple fluorine atoms, these fluorine atoms can be bonded to the same carbon atom or to different carbon atoms. Examples of fluorinated chain carbonates include dimethyl fluorinated carbonate derivatives, methyl ethyl fluorinated carbonate derivatives, and diethyl fluorinated carbonate derivatives.

[0100] In some embodiments, the carboxylic acid ester solvent includes cyclic carboxylic acid esters and / or chain carbonates. Examples of cyclic carboxylic acid esters include one or more of γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Examples of chain carbonates include one or more of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate.

[0101] In some embodiments, the sulfone solvent includes cyclic sulfones and chain sulfones, but preferably, in the case of cyclic sulfones, it is typically a compound with 3 to 6 carbon atoms, more preferably 3 to 5 carbon atoms, and in the case of chain sulfones, it is typically a compound with 2 to 6 carbon atoms, more preferably 2 to 5 carbon atoms. There are no particular limitations on the amount of sulfone solvent added, and it is arbitrary within a range that does not significantly impair the performance of the high-pressure lithium-ion battery of the present invention. Relative to the total amount of solvent in the non-aqueous electrolyte, it is typically 0.3% or more by volume, preferably 0.5% or more by volume, more preferably 1% or more by volume, and typically 40% or less by volume, preferably 35% or less by volume, more preferably 30% or less by volume. When using two or more sulfone solvents in combination, the total amount of sulfone solvent should satisfy the above range. When the amount of sulfone solvent added is within the above range, an electrolyte with excellent high-temperature storage stability is tended to be obtained.

[0102] In a preferred embodiment, the solvent is a mixture of cyclic carbonates and chain carbonates.

[0103] Another embodiment of the present invention provides a battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte as described above.

[0104] Because the battery uses the non-aqueous electrolyte described above, it can form a high-performance passivation film on the positive and negative electrodes, thereby effectively improving the battery's high-temperature storage performance and high-temperature cycle performance, and enhancing the battery's power characteristics.

[0105] In some embodiments, the battery is a secondary battery, which may be a lithium secondary battery, potassium secondary battery, sodium secondary battery, magnesium secondary battery, zinc secondary battery, aluminum secondary battery, etc.

[0106] In a preferred embodiment, the battery is a lithium metal battery, a lithium-ion battery, a lithium-sulfur battery, or a sodium-ion battery.

[0107] In some embodiments, the positive electrode includes a positive electrode active material layer, which includes a positive electrode active material. The type of positive electrode active material is not particularly limited and can be selected according to actual needs. It can be any positive electrode active material or conversion type positive electrode material that can reversibly insert / deintercalate metal ions (lithium ions, sodium ions, potassium ions, magnesium ions, zinc ions, aluminum ions, etc.).

[0108] In a preferred embodiment, the battery is a lithium-ion battery, and its positive electrode active material can be selected from LiFe. 1-x’ M' x’ PO4, LiMn 2-y’ M y’ O4 and LiNi x Co y Mn z M 1-x-y-z One or more of O2, wherein M' is selected from one or more of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V or Ti, and M is selected from one or more of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V or Ti, and 0≤x'<1, 0≤y'≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1. The positive electrode active material may also be selected from one or more of sulfides, selenides, and halides. More preferably, the positive electrode active material may be selected from LiCoO2, LiFePO4, LiFe 0.8 Mn 0.2 PO4, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.5 Co 0.2 Mn 0.2 Al 0.1 O2, LiMn2O4, LiNi 0.5 Co 0.2 Al 0.3 One or more of O2.

[0109] In a preferred embodiment, the battery is a sodium-ion battery, and its positive electrode active material is selected from one or more of metallic sodium, carbon materials, alloy materials, over-plated metal oxides, over-plated metal sulfides, phosphorus-based materials, titanate materials, and Prussian blue-based materials. The carbon material is selected from one or more of graphite, soft carbon, and hard carbon. The alloy material is selected from an alloy composed of at least two of Si, Ge, Sn, Pb, and Sb. The alloy material can also be selected from an alloy composed of at least one of Si, Ge, Sn, Pb, and Sb with C. The chemical formula of the over-plated metal oxide and the over-plated metal sulfide is M1. x N yM1 can be selected from one or more of Fe, Co, Ni, Cu, Mn, Sn, Mo, Sb, and V; N is selected from O or S; the phosphorus-based material can be selected from one or more of red phosphorus, white phosphorus, and black phosphorus; and the titanate material can be selected from Na2Ti3O7 and Na2Ti6O7. 13 Na4Ti5O 12 Li4Ti5O 12 One or more of NaTi2(PO4)3, wherein the molecular formula of the Prussian blue material is Na x M[M′(CN)6] y ·zH₂O, where M is a transition metal, M′ is a transition metal, and 0 <x≤2,0.8≤y<1,0<z≤20。

[0110] In some embodiments, the positive electrode further includes a positive electrode current collector, and the positive electrode material layer covers the surface of the positive electrode current collector.

[0111] The positive electrode current collector is selected from a metallic material that can conduct electrons. Preferably, the positive electrode current collector includes one or more of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the positive electrode current collector is selected from aluminum foil.

[0112] In some embodiments, the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent, and the positive electrode active material, the positive electrode binder and the positive electrode conductive agent are blended to obtain the positive electrode active material layer.

[0113] In some embodiments, the positive electrode binder includes one or more of the following: polyvinylidene fluoride (PVDF), copolymers of PVDF, polytetrafluoroethylene (PTFE), copolymers of PVDF-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of PVDF-tetrafluoroethylene, copolymers of PVDF-trifluoroethylene, copolymers of PVDF-trichloroethylene, copolymers of PVDF-fluorinated vinylidene, copolymers of PVDF-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene; acrylic resins; and styrene-butadiene rubber.

[0114] In some embodiments, the positive electrode conductive agent includes one or more of the following: metallic conductive agent, carbon-based material, metal oxide-based conductive agent, and composite conductive agent. Specifically, the metallic conductive agent can be metals such as copper powder, nickel powder, and silver powder; the carbon-based material can be carbon-based materials such as conductive graphite, conductive carbon black, conductive carbon fiber, or graphene; the metal oxide-based conductive agent can be tin oxide, iron oxide, zinc oxide, etc.; and the composite conductive agent can be composite powder, composite fiber, etc. More specifically, the conductive carbon black can be one or more of acetylene black, 350G, Ketjen black, carbon fiber (VGCF), and carbon nanotubes (CNTs).

[0115] In some embodiments, the negative electrode includes a negative electrode material layer, the negative electrode material layer includes a negative electrode active material, and the negative electrode active material includes one or more of silicon-based negative electrodes, carbon-based negative electrodes, tin-based negative electrodes, and lithium negative electrodes. Specifically, the silicon-based negative electrode includes one or more of silicon materials, silicon oxides, silicon-carbon composite materials, and silicon alloy materials; the carbon-based negative electrode includes one or more of graphite, hard carbon, soft carbon, graphene, and mesophase carbon microspheres; the tin-based negative electrode includes one or more of tin, tin-carbon, tin oxide, and tin metal compounds; and the lithium negative electrode includes one or more of metallic lithium or lithium alloys. The lithium alloy may specifically be at least one of lithium-silicon alloys, lithium-sodium alloys, lithium-potassium alloys, lithium-aluminum alloys, lithium-tin alloys, and lithium-indium alloys.

[0116] In some embodiments, the negative electrode further includes a negative electrode current collector, and the negative electrode material layer covers the surface of the negative electrode current collector. The material of the negative electrode current collector may be the same as that of the positive electrode current collector, and will not be described in detail here.

[0117] In some embodiments, the negative electrode material layer further includes a negative electrode binder and a negative electrode conductive agent, and the negative electrode active material, the negative electrode binder, and the negative electrode conductive agent are blended to obtain the negative electrode material layer. The negative electrode binder and the negative electrode conductive agent can be the same as the positive electrode binder and the positive electrode conductive agent, respectively, and will not be described in detail here.

[0118] In some embodiments, the battery further includes a separator located between the positive electrode and the negative electrode.

[0119] The diaphragm can be a conventional diaphragm, such as a ceramic diaphragm, a polymer diaphragm, a non-woven fabric, or an inorganic-organic composite diaphragm, including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP, and triple-layer PP / PE / PP diaphragms.

[0120] The present invention will be further illustrated by the following examples.

[0121] Table 1

[0122]

[0123]

[0124] Note: The compounds used in the following examples and comparative examples are selected from Table 1.

[0125] Examples 1-13

[0126] This embodiment illustrates the preparation method of the non-aqueous electrolyte and battery disclosed in this invention, including the following steps:

[0127] 1) Preparation of non-aqueous electrolyte:

[0128] Ethylene carbonate (EC), diethyl carbonate (DEC), and methyl ethyl carbonate (EC) were mixed in a mass ratio of EC:DEC:EC = 1:1:1. Then, lithium hexafluorophosphate (LiPF6) was added to a molar concentration of 1 mol / L. Based on the total weight of the non-aqueous electrolyte as 100%, additives were added in the mass percentages shown in Examples 1 to 13 of Tables 2 to 4.

[0129] 2) Preparation of the positive electrode plate:

[0130] The positive electrode active material, lithium nickel cobalt manganese oxide (LiNiO), was mixed in a mass ratio of 93:4:3. 0.5 Co 0.2 Mn 0.3 O2, conductive carbon black Super-P, and binder polyvinylidene fluoride (PVDF) are dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. The slurry is uniformly coated on both sides of an aluminum foil, dried, calendered, and vacuum dried, and then aluminum leads are welded on using an ultrasonic welder to obtain a positive electrode plate with a thickness between 12-15 μm.

[0131] 3) Preparation of the negative electrode plate:

[0132] Artificial graphite, conductive carbon black Super-P, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 94:1:2.5:2.5, and then 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 nickel leads were welded on using an ultrasonic welder to obtain a negative electrode plate with a thickness between 120-150 μm.

[0133] 4) Cell fabrication:

[0134] A three-layer separator with a thickness of 20 μm is placed between the positive and negative plates. Then, the sandwich structure composed of the positive plate, negative plate and separator is wound up, and the wound body is flattened and placed in an aluminum foil packaging bag. It is then vacuum baked at 75°C for 48 hours to obtain the cell to be injected with electrolyte.

[0135] 5) Electrolyte injection and formation of the battery cell:

[0136] In a glove box where the dew point is controlled below -40°C, the electrolyte prepared above is injected into the battery cell, vacuum sealed, and left to stand for 24 hours.

[0137] The initial formation was then performed as follows: constant current charging at 0.05C for 180 minutes, constant current charging at 0.2C to 3.95V, followed by a second vacuum sealing. Then, it was further charged at a constant current of 0.2C to 4.2V, left to stand at room temperature for 24 hours, and finally discharged at a constant current of 0.2C to 3.0V to obtain a LiNi alloy. 0.5 Co 0.2 Mn 0.3 O2 / artificial graphite lithium-ion battery.

[0138] Comparative Examples 1-5

[0139] This comparative example is used to illustrate the non-aqueous electrolyte and battery methods disclosed in this invention, including most of the operational steps in Example 1, with the following differences:

[0140] In the preparation of the non-aqueous electrolyte, additives are added in the mass percentages shown in Comparative Examples 1 to 5 in Tables 2 to 4.

[0141] Performance testing

[0142] The lithium-ion batteries prepared in Examples 1-13 and Comparative Examples 1-5 were subjected to the following performance tests: High-temperature storage performance test

[0143] The formed lithium-ion battery was charged at room temperature with a constant current of 1C to 4.2V, then charged with a constant current and constant voltage until the current dropped to 0.05C. It was then discharged at a constant current of 1C to 3.0V. The initial discharge capacity D1, initial battery volume V1, and initial impedance F1 were measured. After being fully charged, the battery was stored at 60℃ for 30 days, then discharged at 1C to 3V. The retention capacity D2, recovery capacity D3, impedance after storage F2, and battery volume V2 after storage were measured. The calculation formulas are as follows:

[0144] Battery capacity retention rate (%) = Retained capacity D2 / Initial capacity D1 × 100%;

[0145] Battery capacity recovery rate (%) = Recovered capacity D3 / Initial capacity D1 × 100%;

[0146] Volume expansion rate (%) = (Battery volume after storage V2 - Initial battery volume V1) / Initial battery volume V1 × 100%;

[0147] Internal resistance growth rate (%) = Impedance after storage F2 / Initial impedance F1 × 100%.

[0148] 1. Fill in Table 2 with the test results obtained from Examples 1-6 and Comparative Examples 1-4.

[0149] Table 2

[0150]

[0151] Comparing the test results of Examples 1-6 and Comparative Examples 1-4, it can be seen that, compared with traditional vinylene carbonate (VC), vinyl sulfate (DTD), and 1,3-propanesulfonate lactone (PS), using the compound shown in Structural Formula 1 provided in this application as an additive can more significantly improve the storage performance of lithium-ion batteries at high temperatures. This indicates that the silicon-containing groups connecting multiple cyclic structures A introduced in this application have a more stable structure in the passivation film obtained by decomposing them on the electrode surface. The silicon-oxygen bonds between multiple cyclic structures A have a cross-linking effect, ensuring the bonding effect between the decomposition products of multiple cyclic structures A. Therefore, the passivation film formed by the compound shown in Structural Formula 1 has better high-temperature stability and lower internal resistance.

[0152] 2. Fill the test results obtained in Examples 1, 7-12 into Table 3.

[0153] Table 3

[0154]

[0155]

[0156] Comparing the test results of Examples 1 and 7-12, it can be seen that as the amount of compound shown in Structural Formula 1 increases, the high-temperature storage performance of the lithium-ion battery first improves and then decreases. In particular, when the amount of compound shown in Structural Formula 1 is between 0.5% and 5%, the lithium-ion battery exhibits optimal high-temperature storage performance. That is, when the amount of compound shown in Structural Formula 1 is too low, the performance improvement of the lithium-ion battery is not significant. However, the amount of compound shown in Structural Formula 1 added is not necessarily better the more it is added. The reason is that as the content of compound shown in Structural Formula 1 increases, the composition of the passivation film on the electrode surface changes. Since the composition of the passivation film is relatively complex, including mixed products from the decomposition of electrolyte salts, solvents, and additives, its performance is the comprehensive performance of the combination of various components. If too much compound shown in Structural Formula 1 is added, the content of components from the decomposition products of compound shown in Structural Formula 1 in the passivation film becomes too high, which is detrimental to the suppression effect of gas generation under high-temperature storage and also leads to an increase in internal resistance.

[0157] 3. Fill the test results obtained from Example 1, Example 13, Comparative Example 3 and Comparative Example 5 into Table 4.

[0158] Table 4

[0159]

[0160] Comparing the test results in Table 4, it can be seen that compared with the traditional combination additives of vinylene carbonate (VC) and vinyl sulfate (DTD), or the addition of vinyl sulfate (DTD) alone, or the addition of the compound shown in Structural Formula 1 alone, the combination of the compound shown in Structural Formula 1 provided in this application with vinyl sulfate (DTD) can further improve the high-temperature storage performance of the battery. This indicates that the decomposition products of the compound shown in Structural Formula 1 have good affinity with the decomposition products of vinyl sulfate (DTD), and the combined product obtained by the two has higher stability at high temperatures than its individual decomposition products. Therefore, the passivation film formed by the compound shown in Structural Formula 1 and vinyl sulfate exhibits superior high-temperature stability.

[0161] 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 within the protection scope of the present invention.

Claims

1. A non-aqueous electrolyte, characterized in that, Including at least one of the compounds shown in structural formula 1: Structural Formula 1 Where n is a natural number from 0 to 4, and A is selected from cyclic sulfate groups and their derivatives, cyclic sulfonate groups and their derivatives, or cyclic sulfite groups and their derivatives. The cyclic sulfate groups and their derivatives are selected from groups shown in structural formula 2: Structural Formula 2 in, For the bonding positions, a, b, and c are natural numbers, and the sum of a, b, and c is 0 or 1. R1, R2, and R3 are each independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens. The cyclic sulfonate groups and their derivatives are selected from the groups shown in structural formula 3: Structural Formula 3 in, For the bonding position, d, e, and f are natural numbers, and the sum of d, e, and f is 0, 1, or 2. R4, R5, and R6 are each independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and groups in which at least one hydrogen atom of a C1-C5 alkyl group is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens. The cyclic sulfite group and its derivatives are selected from the groups shown in structural formula 5: Structural Formula 5 in, For the bonding position, g, h, and i are natural numbers, and the sum of g, h, and i is 0 or 1, R 10 R 11 R 12 Each of the following groups is independently selected from hydrogen, halogen atoms, C1-C5 alkyl groups, heteroatom-containing groups, and C1-C5 alkyl groups in which at least one hydrogen atom is replaced by a heteroatom-containing group, wherein the heteroatom includes one or more of O, N, S, or halogens. Based on the total mass of the non-aqueous electrolyte being 100%, the amount of the compound represented by structural formula 1 added is 0.01~10%.

2. 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: 。 3. The non-aqueous electrolyte according to claim 1, characterized in that, The non-aqueous electrolyte further includes an electrolyte salt selected from LiPF6, LiBOB, LiDFOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO2F)2, LiClO4, LiAlCl4, LiCF3SO3, and Li2B. 10 Cl 10 At least one of the following: lithium salts of lower aliphatic carboxylic acids.

4. The non-aqueous electrolyte according to claim 1, characterized in that, The non-aqueous electrolyte also includes auxiliary additives, which include at least one of cyclic sulfate compounds, sulfonyl lactone compounds, cyclic carbonate compounds, unsaturated phosphate compounds, and nitrile compounds.

5. The non-aqueous electrolyte according to claim 4, characterized in that, The cyclic sulfate compound is selected from at least one of vinyl sulfate, propylene sulfate, or methyl vinyl sulfate; The sulfonyl lactone compound is selected from at least one of 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, or 1,3-propenesulfonyl lactone. The cyclic carbonate compound is selected from at least one of vinylene carbonate, ethylene ethylene carbonate, fluoroethylene carbonate, or the compound shown in structural formula 6. Structural Formula 6 In structural formula 6, R 21 R 22 R 23 R 24 R 25 R 26 Each is independently selected from one of the following: hydrogen atom, halogen atom, or C1-C5 group; The unsaturated phosphate compound is selected from at least one of the compounds shown in structural formula 7: Structural Formula 7 In structural formula 7, R 31 R 32 R 32 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group; The nitrile compounds include one or more of the following: succinic acid, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptacyanide, octadionitrile, nonadionitrile, and sebaconitol.

6. 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 5.

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