Electrolyte and battery

Abstract

An electrolyte and a battery. The electrolyte is provided. The electrolyte comprises an additive, wherein the additive has a structure as shown in formula 1. The provided phosphate electrolyte additive has a three-dimensional skeleton structure as shown in formula 1, not only can participate in formation of an SEI film, but also can construct a cavity channel in the film forming process, thus improving the porosity of the SEI film, improving the ion transmission efficiency, reducing the impact of temperature on the ion transmission efficiency, and further improving the high and low temperature performance of batteries.

Description

Electrolyte and battery

[0001] This application claims priority to the Chinese patent applications filed with the China Patent Office on June 12, 2023, with application number 2023106913559 and application name “A kind of electrolyte and battery” and the Chinese patent application filed with the China Patent Office on June 12, 2023, with application number 2023106913544 and application name “A kind of electrolyte and battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to an electrolyte and a battery, and to the technical field of batteries. Background Art

[0003] Batteries are widely used as energy supply devices. As one of the key components of batteries, electrolytes include non-aqueous solvents, electrolytes, and additives. Suitable additives can effectively improve battery performance.

[0004] Phosphate compounds are widely recognized as electrolyte additives by those skilled in the art. For example, Chinese invention patent publication number CN114899490A provides a cyclic phosphate additive containing an unsaturated five-membered cyclic phosphate ester and its derivatives, which helps improve the room temperature cycling performance, high temperature cycling performance, and high temperature storage performance of lithium-ion batteries. Chinese invention patent publication number CN114824484A provides a cyclic phosphate electrolyte additive that helps improve the room temperature cycling performance and first coulombic efficiency of lithium-ion batteries. Chinese invention patent publication number CN115377495A provides a phosphate additive that helps improve the room temperature cycling stability of high-nickel ternary / silicon-carbon system lithium-ion batteries. Chinese patent publication number CN115832436A provides an electrolyte that can balance high and low temperature performance. Through the combined action of a triphenylphosphine compound and a compound having a carbonyl group, it improves the battery's low temperature rate discharge performance and room temperature and high temperature cycle life. How to improve the high and low temperature performance of batteries using a single-component phosphate compound is one of the research directions of those skilled in the art.

[0005] Summary of the Invention

[0006] The present application provides an electrolyte for improving the high and low temperature performance of a battery.

[0007] The present application also provides a battery comprising the above-mentioned electrolyte.

[0008] In a first aspect, the present application provides an electrolyte, wherein the electrolyte includes a first additive, wherein the first additive has a structure shown in Formula 1:

[0009] In Formula 1, R1 is selected from H, halogen, phenyl, alkylene-phenyl, substituted or unsubstituted C1-C10 saturated hydrocarbon group, substituted or unsubstituted C2-C10 olefin group, substituted or unsubstituted C2-C10 alkynyl group, and the substituent is selected from one or more of hydroxyl group and halogen; R2, R3, R4, R5, R6, and R7 are independently selected from one of H, halogen, C1-C10 saturated hydrocarbon group, C2-C10 olefin group, C2-C10 alkynyl group, C1-C10 halogenated saturated hydrocarbon group, C2-C10 halogenated olefin group, and C2-C10 halogenated alkynyl group.

[0010] In the electrolyte as described above, R1 is selected from alkylene-phenyl, substituted or unsubstituted C1-C10 saturated hydrocarbon group, substituted or unsubstituted C2-C10 olefin group, substituted or unsubstituted C2-C10 alkynyl group, and the substituent is selected from one or more of hydroxyl group and halogen.

[0011] In the electrolyte as described above, R1 is selected from a substituted or unsubstituted C2-C4 saturated hydrocarbon group, a C2-C4 olefin group, or a C2-C4 alkynyl group, and the substituent is selected from one or more of a hydroxyl group and a halogen.

[0012] In the electrolyte as described above, R2, R3, R4, R5, R6, and R7 are independently selected from one of H, a C1-C10 saturated hydrocarbon group, and a C1-C10 halogenated hydrocarbon group.

[0013] In the electrolyte described above, the first additive is one or more compounds represented by Formula 1-1 to Formula 1-13, wherein:

[0014] In the electrolyte as described above, the mass of the first additive is 0.1%-10% of the total mass of the electrolyte.

[0015] The electrolyte as described above further comprises a second additive, wherein the second additive is selected from one or more of vinylene carbonate, vinyl sulfate, vinyl ethylene carbonate, 1,3-propane sultone, and fluoroethylene carbonate.

[0016] In the electrolyte as described above, the mass ratio of the first additive to the second additive is 1:(0.1-3.0).

[0017] The electrolyte as described above further comprises a non-aqueous organic solvent and a lithium salt.

[0018] In the electrolyte as described above, the lithium salt is selected from one or more of inorganic lithium salts, lithium carboxylates, lithium sulfonates, lithium imides, lithium methylates, lithium borates, lithium oxalates, and fluorine-containing organic lithium salts.

[0019] In the electrolyte as described above, the concentration of the lithium salt is 0.5M-2M.

[0020] In the electrolyte as described above, the non-aqueous organic solvent includes one or more of carbonate compounds, carboxylate compounds, ether compounds, and sulfone compounds.

[0021] The electrolyte as described above further comprises a third additive, wherein the third additive is selected from one or more of a film-forming additive, a conductive additive, a flame retardant additive, an overcharge protection additive, and an additive for improving high and low temperature performance.

[0022] A second aspect of the present application provides a battery comprising any of the above-mentioned electrolytes.

[0023] The phosphate electrolyte additive provided in the present application has a three-dimensional skeleton structure as shown in Formula 1. It can not only participate in the formation of the SEI film, but also construct cavity channels during the film formation process, thereby increasing the porosity of the SEI film, which is beneficial to improving the ion transmission efficiency, reducing the impact of temperature on the ion transmission efficiency, and thus improving the high and low temperature performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] FIG1 is an H spectrum of the electrolyte additive shown in Formula 1-1 provided in Example 1 of the present application;

[0026] FIG2 is a P spectrum of the electrolyte additive shown in Formula 1-1 provided in Example 1 of the present application. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] In a first aspect, the present application provides an electrolyte solution comprising an additive having a structure shown in Formula 1:

[0029] In Formula 1, R1 is selected from H, halogen, phenyl, alkylene-phenyl, substituted or unsubstituted C1-C10 saturated hydrocarbon group, substituted or unsubstituted C2-C10 olefin group, substituted or unsubstituted C2-C10 alkynyl group, and the substituent is selected from one or more of hydroxyl group and halogen; R2, R3, R4, R5, R6, and R7 are independently selected from one of H, halogen, C1-C10 saturated hydrocarbon group, C2-C10 olefin group, C2-C10 alkynyl group, C1-C10 halogenated saturated hydrocarbon group, C2-C10 halogenated olefin group, and C2-C10 halogenated alkynyl group.

[0030] In this application, a saturated hydrocarbon group refers to an alkyl group having a corresponding number of carbon atoms and having the general structural formula -C n H 2n+1 When an alkyl group having a specific number of carbon atoms is specified, all geometric isomers having that number of carbon atoms are included. For example, a saturated hydrocarbon group is selected from methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, methylcyclopentyl, ethylcyclopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, octyl, cyclopropyl, cyclobutyl, etc. In addition, any H atom in the saturated hydrocarbon group may be substituted.

[0031] In the present application, alkene group refers to an unsaturated hydrocarbon group having a corresponding number of carbon atoms and containing one or more carbon-carbon double bonds. For example, alkene group is selected from vinyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, aromatic hydrocarbons, etc. In addition, any H atom in the alkene group may be substituted.

[0032] In the present application, an alkynyl group refers to an unsaturated hydrocarbon group having a corresponding number of carbon atoms and containing one or more carbon-carbon triple bonds. For example, the alkynyl group is selected from ethynyl, n-propynyl, isopropynyl, n-but-2-ynyl, but-3-ynyl, n-hex-3-ynyl, etc. In addition, any H atom in the alkene group may be substituted.

[0033] In the present application, alkylene refers to a saturated straight-chain or branched divalent group having the corresponding number of carbon atoms and derived from the corresponding alkane by removing two hydrogen atoms. Alkylene-phenyl refers to an alkylene group connected to an aryl group.

[0034] The phosphate electrolyte additive provided in the present application has a three-dimensional skeleton structure as shown in Formula 1. It can not only participate in the formation of the SEI film, but also construct cavity channels during the film formation process, thereby increasing the porosity of the SEI film, which is beneficial to improving the ion transmission efficiency, reducing the impact of temperature on the ion transmission efficiency, and thus improving the high and low temperature performance of the battery.

[0035] In a specific embodiment, R1 is selected from alkylene-phenyl, substituted or unsubstituted C1-C10 saturated hydrocarbon group, substituted or unsubstituted C2-C10 alkene group, substituted or unsubstituted C2-C10 alkynyl group, and the substituent is selected from one or more of hydroxyl group and halogen.

[0036] In a specific embodiment, R1 is selected from substituted or unsubstituted C2-C4 saturated hydrocarbon groups, C2-C4 olefin groups, C2-C4 alkyne groups, and the substituents are selected from one or more of hydroxyl groups, halogen groups,

[0037] In a specific embodiment, R2, R3, R4, R5, R6, and R7 are independently selected from one of H, a C1-C10 saturated hydrocarbon group, and a C1-C10 halogenated hydrocarbon group.

[0038] Furthermore, the additive is one or more compounds represented by Formula 1-1 to Formula 1-13, wherein:

[0039] The compounds represented by Formulas 1-1 to 1-13 provided herein have suitable substituent groups, which help to further improve the porosity and stability of the SEI film.

[0040] In a specific embodiment, taking into account the effect of the first additive, the content of the first additive is generally not less than 0.1%, but too much content of the first additive will increase the viscosity and ionic conductivity of the electrolyte, affecting the capacity and impedance of the battery. Therefore, in the electrolyte, the mass of the first additive is 0.1%-10% of the total mass of the electrolyte, specifically 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0% or within the range of any two thereof.

[0041] Furthermore, the mass of the first additive is 0.5%-5% of the total mass of the electrolyte.

[0042] In one embodiment, the electrolyte further includes a second additive, which is a film-forming additive selected from one or more of vinylene carbonate, vinyl sulfate, vinyl ethylene carbonate, 1,3-propane sultone, and fluoroethylene carbonate. The combination of the first additive shown in Formula 1 and the second additive further improves the high- and low-temperature performance of the battery.

[0043] Furthermore, the second additive produces more gas under high temperature conditions, affecting the high temperature storage performance and cycle performance of the battery. Therefore, the content of the second additive should not be too high. Specifically, the mass ratio of the first additive to the second additive is 1:(0.1-3.0), which can be 1:0.1, 1:0.2, 1:0.5, 1:1.0, 1:1.2, 1:1.5, 1:1.8, 1:2.5, 1:2.2, 1:2.5, 1:2.8 or 1:3.0 or within the range of any two thereof.

[0044] Furthermore, the mass ratio of the first additive to the second additive is 1:(0.1-1.0).

[0045] The electrolyte provided in the present application also includes a non-aqueous organic solvent and a lithium salt. The types of the non-aqueous organic solvent and the lithium salt can be conventional materials in the art. Specifically, the non-aqueous organic solvent includes one or more of carbonate compounds, carboxylate compounds, ether compounds, and sulfone compounds.

[0046] Specifically, the carbonate compounds include one or more of cyclic carbonates and linear carbonates. Cyclic carbonates include one or more of ethylene carbonate (EC) and propylene carbonate (PC); linear carbonates include one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and methylpropyl carbonate (MPC).

[0047] Carboxylate compounds include cyclic carboxylates and linear carboxylates. Cyclic carboxylates include one or more of γ-butyrolactone, γ-valerolactone, γ-caprolactone, and ε-caprolactone; linear carboxylates include one or more of methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate (PP), ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, tert-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, and isopropyl isobutyrate.

[0048] The ether compound can be a chain ether having 3 to 10 carbon atoms, or a cyclic ether having 3 to 6 carbon atoms. For example, the chain ether having 3 to 10 carbon atoms is selected from ethyl ether, di(2-fluoroethyl) ether, di(2,2-difluoroethyl) ether, di(2,2,2-trifluoroethyl) ether, ethyl(2-fluoroethyl) ether, ethyl(2,2,2-trifluoroethyl) ether, ethyl(1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl)(2,2,2-trifluoroethyl) ether, (2-fluoroethyl)(1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl)(1,1,2,2-tetrafluoroethyl) ether, ethyl-n-propyl ether, ethyl(3-fluoro-n-propyl) ether, ethyl(3, 3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-tetrafluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propyl ether, (2-fluoroethyl) (3-fluoro-n-propyl) ether, (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl-n-propyl ether, (2,2,2-trifluoroethyl) (3-fluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ) ether, (2,2,2-trifluoroethyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl)(3-fluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl)(3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl)(2,2,3,3-pentafluoro-n-propyl) ether, di-n-propyl ether, (n-propyl)(3-fluoro-n-propyl) ether, (n-propyl)(3,3,3-trifluoro-n-propyl) ether, (n-propyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (n-propyl)(2,2 ,3,3,3-pentafluoro-n-propyl) ether, bis(3-fluoro-n-propyl) ether, (3-fluoro-n-propyl)(3,3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (3-fluoro-n-propyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, bis(3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, bis(2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, bis(2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, methoxy(2-fluoroethoxy)methane, methoxy(2,2,2-trifluoroethoxy)methane, methoxy(1,1,2,2-tetrafluoroethoxy)methane, diethoxymethane, ethoxy(2-fluoroethoxy)methane, ethoxy(2,2,2-trifluoroethoxy)methane, ethoxy(1,1,2,2-tetrafluoroethoxy)methane, di(2-fluoroethoxy)methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy)methane, (2-fluoroethoxy)(1,1,2,2-tetrafluoroethoxy)methane, bis(2,2,2-trifluoroethoxy)methane, (2,2,2-trifluoroethoxy)(1,1,2,2-tetrafluoroethoxy)methane, bis(1,1,2,2-tetrafluoroethoxy)methane, dimethoxyethane, methoxyethoxyethane, methoxy(2-fluoroethoxy)ethane, methoxy(2,2,2-trifluoroethoxy)ethane, methoxy(1,1,2, 2-Tetrafluoroethoxy)ethane, Diethoxyethane, Ethoxy(2-fluoroethoxy)ethane, Ethoxy(2,2,2-trifluoroethoxy)ethane, Ethoxy(1,1,2,2-tetrafluoroethoxy)ethane, Di(2-fluoroethoxy)ethane, (2-fluoroethoxy)(2,2,2-trifluoroethoxy)ethane, (2-fluoroethoxy)(1,1,2,2-tetrafluoroethoxy)ethane, Di(2,2,2-trifluoroethoxy)ethane, (2,2,2-trifluoroethoxy)(1,1 One or more of 2,2-tetrafluoroethoxy)ethane, di(1,1,2,2-tetrafluoroethoxy)ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether; one or more of the cyclic ethers having 3 to 6 carbon atoms selected from tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, and 1,4-dioxolane.

[0049] Furthermore, some hydrogen atoms in the molecular structure of the ether compound are optionally replaced by fluorine.

[0050] When the ether compound is used as an auxiliary solvent, and the negative electrode active material is a carbonaceous material, it is easy to avoid the problem of co-intercalation of the ether compound and lithium ions, which leads to a decrease in capacity.

[0051] The sulfone compound is selected from one or more of dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, tert-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-tert-butyl sulfone, trifluoromethyl-n-butyl sulfone, and trifluoromethyl-tert-butyl sulfone. When the sulfone compound is present as an auxiliary solvent, the cycle performance and cycle retention performance of the battery can be improved, the solution viscosity can be reduced, and the electrochemical performance can be improved.

[0052] In a preferred embodiment, the solvent used in the present application includes both a cyclic organic solvent and a linear organic solvent. The following lists the optional solvent combinations:

[0053] The non-aqueous organic solvent includes ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC) and methyl propionate (PP), and the mass ratio of EC, PC, DEC and PP is 1-10:1-10:1-10:1-10. Further, the mass ratio of EC, PC, DEC and PP is 1-10:1:1-10:1-10.

[0054] The non-aqueous organic solvent includes ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC), and the mass ratio of EC, DEC and EMC is 1:0.1-10:0.1-10; further, the mass ratio of EC, DEC and EMC is 1:0.2-5:0.2-5; further, the mass ratio of EC, DEC and EMC is 1:0.5-2:0.5-2.

[0055] The non-aqueous organic solvent includes ethylene carbonate (EC), propylene carbonate (PC) and ethyl methyl carbonate (EMC), and the mass ratio of EC, PC and EMC is 1:0.1-10:0.1-10; further, the mass ratio of EC, PC and EMC is 1:0.2-5:0.2-5; further, the mass ratio of EC, PC and EMC is 1:0.5-2:0.5-2.

[0056] The non-aqueous organic solvent includes ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), and the mass ratio of EC, DMC and EMC is 1:0.1-10:0.1-10; further, the mass ratio of EC, DMC and EMC is 1:0.2-5:0.2-5; further, the mass ratio of EC, DMC and EMC is 1:0.5-2:0.5-2.

[0057] In the present application, the lithium salt may be selected from one or more of inorganic lithium salts, lithium carboxylates, lithium sulfonates, lithium imides, lithium methylates, lithium borates, lithium oxalates, and fluorine-containing organic lithium salts. Specifically, the inorganic lithium salt is selected from one or more of LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, LiTaF6, and LiWF7; the lithium carboxylates are selected from one or more of HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2C One or more of O2Li, CF3CF2CF2CO2Li, CF3CF2CF2CF2CO2Li; lithium sulfonate salts selected from one or more of FSO3Li, CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li; lithium imide salts selected from LiN(FCO)2, LiN(FCO)(FSO2), bis(fluorosulfonyl)imide lithium LiN(FSO2) 2. One or more of LiN(FSO2)(CF3SO2), lithium bis(trifluoromethanesulfonyl)imide LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, and LiN(CF3SO2)(C4F9SO2); one or more of a methylated lithium salt selected from LiC(FSO2)3, LiC(CF3SO2)3, and LiC(C2F5SO2)3; one or more of a lithium borate salt selected from lithium difluorooxalatoborate and lithium bisoxalatoborate or two; lithium oxalate salt is selected from one or more of lithium tetrafluorooxalatophosphate, lithium difluorobisoxalatophosphate, and lithium trioxalato)phosphate; fluorine-containing organic lithium salt is selected from one or more of LiPF4(CF3)2, LiPF4(C2F5)2, LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, and LiBF2(C2F5SO2)2.

[0058] Furthermore, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorooxalatophosphate, lithium tetrafluorooxalatophosphate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide.

[0059] Further, the concentration of the lithium salt is 0.5M-2M, further, the concentration of the lithium salt is 0.5M-1.5M, further, the concentration of the lithium salt is 0.7M-1.5M.

[0060] In addition, the electrolyte provided in this application also includes other additives, which are selected from one or more of film-forming additives, conductive additives, flame retardant additives, overcharge protection additives, and additives for improving high and low temperature performance. The specific types and addition amounts can be set as needed.

[0061] In a specific embodiment, the additive for improving the high and low temperature performance is selected from one or more of vinylene carbonate, vinyl sulfate, vinyl ethylene carbonate, 1,3-propane sultone, and fluoroethylene carbonate. The compound represented by Formula 1 is used in combination with the above additives to help further optimize the high and low temperature performance of the battery.

[0062] A second aspect of the present application provides a battery comprising any of the above-mentioned electrolytes.

[0063] Based on the electrolyte provided in the first aspect of the present application, the battery provided in the present application has good high and low temperature performance.

[0064] In a specific embodiment, the battery is a lithium-ion battery, which, in addition to the electrolyte provided in the first aspect of the present application, further comprises a positive electrode sheet, a negative electrode sheet, and a separator. Specifically:

[0065] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, a conductive agent and a binder. The positive electrode current collector is generally an aluminum foil, and the positive electrode active material is selected from lithium transition metal oxides, such as LiCoO2, LiMn2O4, LiMnO2, Li2MnO4, LiFePO4, Li 1+a Mn 1-x M x O2、LiCo 1-x M x O2、LiFe 1-x M x PO4, Li2Mn 1-x O4, M is selected from one or more of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B, and F, 0≤a<0.2, 0≤x<1.

[0066] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer arranged on the surface of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, a conductive agent and a binder. Among them, the negative electrode current collector is generally copper foil, and the negative electrode active material is selected from one or more of carbonaceous materials, silicon-carbon materials, alloy materials, and lithium-containing metal composite oxides.

[0067] The conductive agent and the binder in the positive electrode active material layer and the negative electrode active material layer can be conventional materials in the art.

[0068] The diaphragm includes one or more of polyolefin, aromatic polyamide, polytetrafluoroethylene, and polyethersulfone, and can be specifically configured according to needs.

[0069] The solution provided by this application is described in detail below with reference to specific embodiments:

[0070] Example 1

[0071] The electrolyte provided in this embodiment includes a non-aqueous organic solvent, a lithium salt and an additive, wherein the non-aqueous organic solvent includes ethylene carbonate (EC), propylene carbonate (PC), methyl propionate (PP), and diethyl carbonate (DEC), and the mass ratio of EC:PC:PP:DEC is 3:2:5:5; the lithium salt is LiPF6, and its concentration is 1 mol / L; the additive has the structure shown in Formula 1-1, and its mass accounts for 1.0% of the total mass of the electrolyte.

[0072] The preparation method of the compound represented by Formula 1-1 is as follows: 5 g of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol is added to a three-necked flask, and then 25 mL of 1,4-dioxane is added. The mixture is heated to 95° C. under a nitrogen atmosphere and reacted with an excess of phosphorus oxychloride for 4 hours. After the reaction is completed, the solvent is evaporated and the resulting crude product is recrystallized with distilled water and then dried in vacuo at 70° C. to obtain a white solid. The white solid is subjected to nuclear magnetic resonance analysis. The H spectrum and P spectrum obtained by the analysis are shown in FIG1-2, which proves that the compound represented by Formula 1-1 has indeed been synthesized. The reaction formula involved is as follows:

[0073] The electrolyte formulas provided in Examples 2 to 16 and Comparative Examples 1 to 6 are basically the same as those in Example 1, except that: the types of the first additives used in Examples 2 to 9 are different; the volume ratio of the non-aqueous organic solvent in Example 10 is different; the composition of the non-aqueous organic solvent in Example 11 is different; the types of lithium salts in Example 12 are different; the contents of the first additives used in Examples 13 to 16 are different, no additive having the structure shown in Formula 1 is added in Comparative Examples 1 to 2; and the additives used in Comparative Examples 3 to 6 are compounds shown in Formulas 2 to 4. The specific differences are listed in Table 1.

[0074] Examples 17 to 20 also include a second additive; Examples 21 to 45 and Comparative Examples 7 to 9 provide electrolyte formulations that are substantially the same as Example 17, except that: the contents of the first additive and the second additive are different in Examples 21 to 33; the volume ratio of the non-aqueous organic solvent is different in Example 34; the types of the first additive are different in Examples 35 to 45, and Comparative Examples 7 to 9 include only the second additive and do not include the first additive. The specific differences are listed in Table 2.

[0075] Table 1 Electrolyte compositions provided in Examples 1 to 16 and Comparative Examples 1 to 6

[0076] Table 2 Electrolyte compositions provided in Examples 17 to 45 and Comparative Examples 7 to 9

[0077] The electrolytes provided in Examples 1 to 45 and Comparative Examples 1 to 9 were assembled with the positive electrode sheet, the separator, and the negative electrode sheet to obtain a lithium-ion battery, and the preparation method thereof was as follows:

[0078] The positive electrode material (NCM523), the conductive agent SuperP (conductive carbon black) and CNT (carbon nanotube), and the adhesive PVDF (polyvinylidene fluoride) were mixed uniformly in a mass ratio of 96.3:2:0.5:1.2 to prepare a positive electrode active material layer slurry, which was then coated on the surface of aluminum foil, dried at 85°C, and cold pressed. The slurry was then trimmed, cut, and striped. After stripping, it was dried at 95°C under vacuum for 12 hours, and the tabs were welded to obtain a surface density of 33 mg / cm 2 The positive electrode.

[0079] Graphite, conductive agent SuperP, thickener CMC, and adhesive SBR (styrene-butadiene rubber emulsion) were mixed in a mass ratio of 95:1.5:1.0:2.5 to prepare a negative electrode active material layer slurry, mixed evenly, and coated on the surface of copper foil. After drying at 85°C, cold pressing was performed. The slurry was then trimmed, cut, and striped. After stripping, it was dried at 85°C under vacuum for 12 hours and the tabs were welded to obtain a surface density of 20.3 mg / cm 2 The negative electrode.

[0080] The positive electrode, separator and negative electrode are laminated to form a lithium-ion battery with a thickness of 4.7mm, a width of 55mm and a length of 60mm. The theoretical capacity is 1600mAh. The battery is vacuum baked at 75℃ for 10 hours and the electrolyte is injected. After standing for 24 hours, the battery is charged at a constant current of 0.1C for 6 hours under a pressure of 3kg / cm2, and then aged at 45℃ for 2 days. The battery is charged to 4.4V at 0.1C and charged at a constant voltage until the current drops to 0.05C (80mA). The battery is then discharged to 3.0V at 0.1C to obtain the first effect. The battery is then charged and discharged at 0.5C and 1C for 1 week respectively. Finally, the battery is charged to 3.8V at 1C for storage to complete the battery production.

[0081] The prepared lithium-ion battery was subjected to high and low temperature performance tests. The test method is as follows. The test results are shown in Table 3:

[0082] 25℃ cycle test: Charge at 25℃ at a constant current of 1.0C to 4.4V, charge at a constant voltage of 4.4V to a cutoff current of 0.05C, and then discharge the battery at a constant current of 1.0C. The discharge capacity is recorded as C0. Repeat the charge and discharge steps for 500 cycles to obtain the discharge capacity at the 500th cycle C500. The capacity retention rate = C500 / C0*100.

[0083] 45℃ cycle test: Charge at 45℃ at a constant current of 1.0C to 4.4V, charge at constant voltage to a cutoff current of 0.05C, and then discharge the battery at a constant current of 1.0C. The discharge capacity is recorded as C0. Repeat the charge and discharge steps for 300 cycles to obtain the discharge capacity at the 300th cycle, C300. The capacity retention rate = C300 / C0*100%.

[0084] Capacity retention test after 14 days of storage at 60°C: At 25°C, charge to 4.4V at a constant current of 1.0C, charge to a cutoff current of 0.05C at a constant voltage of 4.4V, then discharge the battery at a constant current of 1.0C, and record the discharge capacity as C0. At 25°C, charge to 4.4V at a constant current of 1.0C, charge to a cutoff current of 0.05C at a constant voltage of 4.4V, then transfer the battery to 60°C and let it sit for 14 days, then discharge the battery at a constant current of 1.0C, and record the discharge capacity as C1. Capacity retention after 14 days of storage at 60°C = C1 / C0*100%.

[0085] -20℃ low temperature discharge test: At 25℃, charge the battery to 4.4V at 1.0C constant current, charge at 4.4V constant voltage to a cutoff current of 0.05C, then discharge the battery at 0.5C constant current. The discharge capacity is recorded as C0. At 25℃, charge the battery to 4.4V at 1.0C constant current, charge at 4.4V constant voltage to a cutoff current of 0.05C, then transfer the battery to -20℃ and let it sit for 240 minutes. Then discharge the battery at 0.5C constant current. The discharge capacity is recorded as C1. -20℃ discharge rate = C1 / C0*100%.

[0086] Table 3 Performance test results of batteries provided by Examples 1 to 45 and Comparative Examples 1 to 9

[0087] According to Table 3, the high and low temperature performance of the lithium ion batteries provided by Examples 1 to 9 and Comparative Examples 3 to 6 are better than those of Comparative Examples 1 to 2, indicating that the additives help improve the high and low temperature performance of the battery, especially the low temperature discharge performance; According to Examples 1 to 9, it can be seen that additives with different structures will affect the performance of the lithium ion battery. For example, when the electrolyte includes the compound of the structure shown in Formula 1-4, the high temperature performance of the lithium ion battery is significantly improved, which is related to the high electronegativity of the F element and the high stability of the interface film formed; when the electrolyte includes the compounds of the structures shown in Formulas 1-7 and 1-8, the cycle storage performance of the lithium ion battery is significantly improved, which is related to the double bond or triple bond being electropolymerized to form a dense interface film. Different numbers of carbon atoms will also affect the performance of lithium-ion batteries. For example, the compounds with structures shown in formulas 1-1 to 1-3 have better battery performance than the compounds shown in formulas 4 to 5. This should be related to the excessive or excessive porosity of the interface film caused by the R1 carbon chain being too short or too long. For example, for hydroxymethyl, the chain length is too short, the gap formed is larger, so that more electrolyte is exposed to the surface for oxidation and decomposition, resulting in electrode polarization. In addition, the HF produced by the decomposition of the electrolyte under high voltage will corrode the electrode more easily, causing damage to the electrode structure, thereby leading to a decrease in room temperature, high temperature cycling and high temperature storage performance; for example, for pentyl, the chain length is too long, the porosity formed is small, and it is difficult for Li+ to be transmitted at the interface, resulting in a decrease in low temperature performance.

[0088] According to Examples 10 to 12 and Example 34, when the composition of the non-aqueous organic solvent and the type of lithium salt in the basic electrolyte are different, the high and low temperature performance of the battery has similar effects, indicating that the compound represented by Formula 1 provided in the present application has good adaptability and is suitable for use in different electrolytes.

[0089] According to Examples 13 to 16, it can be seen that as the content of the additive represented by Formula 1-1 in the electrolyte gradually increases, the high and low temperature performance of the battery is improved, but when the content of the additive is increased to 5%, the performance of the battery decreases. Therefore, the preferred content of the additive represented by Formula 1 is 0.5% to 2%, and more preferably 1%.

[0090] According to Examples 17 to 20 and Comparative Examples 7 to 9, the additive represented by Formula 1-1 has good compatibility with the second additive, which helps to further improve the high and low temperature performance of the battery, and the second additive is preferably vinylene carbonate VC.

[0091] According to Examples 21 to 33, when the content ratio of the first additive to the second additive is about 1:1, it helps to further improve the high and low temperature performance of the lithium-ion battery.

[0092] According to Examples 35 to 37, in the presence of the second additive, compared with the first additive shown in Formula 1-1, although the low-temperature performance will be affected to a certain extent, the room temperature / high temperature performance of the lithium-ion battery is improved.

[0093] According to Examples 38 to 45, other first additives have similar effects to the compound represented by Formula 1-1.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrolyte, wherein The electrolyte includes a first additive having a structure shown in Formula 1: In Formula 1, R1 is selected from H, halogen, phenyl, alkylene-phenyl, substituted or unsubstituted C1-C10 saturated hydrocarbon group, substituted or unsubstituted C2-C10 olefin group, substituted or unsubstituted C2-C10 alkynyl group, and the substituent is selected from one or more of hydroxyl and halogen; R2, R3, R4, R5, R6, and R7 are independently selected from one of H, halogen, C1-C10 saturated hydrocarbon group, C2-C10 olefin group, C2-C10 alkynyl group, C1-C10 halogenated saturated hydrocarbon group, C2-C10 halogenated olefin group, and C2-C10 halogenated alkynyl group.

2. The electrolyte according to claim 1, wherein R1 is selected from alkylene-phenyl, substituted or unsubstituted C1-C10 saturated hydrocarbon group, substituted or unsubstituted C2-C10 olefin group, substituted or unsubstituted C2-C10 alkynyl group, and the substituent is selected from one or more of hydroxyl group and halogen.

3. The electrolyte according to claim 1 or 2, wherein R1 is selected from substituted or unsubstituted C2-C4 saturated hydrocarbon groups, C2-C4 olefin groups, C2-C4 alkynyl groups, and the substituents are selected from one or more of hydroxyl groups and halogen groups.

4. The electrolyte according to any one of claims 1 to 3, wherein The R2, R3, R4, R5, R6 and R7 are independently selected from one of H, a C1-C10 saturated hydrocarbon group and a C1-C10 halogenated hydrocarbon group.

5. The electrolyte according to any one of claims 1 to 4, wherein The first additive is one or more compounds represented by Formula 1-1 to Formula 1-13, wherein:

6. The electrolyte according to any one of claims 1 to 5, wherein The mass of the first additive is 0.1%-10% of the total mass of the electrolyte.

7. The electrolyte according to any one of claims 1 to 6, wherein: The electrolyte further includes a second additive, which is selected from one or more of vinylene carbonate, vinyl sulfate, vinyl ethylene carbonate, 1,3-propane sultone, and fluoroethylene carbonate.

8. The electrolyte according to claim 7, wherein The mass ratio of the first additive to the second additive is 1:(0.1-3.0).

9. The electrolyte according to any one of claims 1 to 8, wherein: The electrolyte also includes a non-aqueous organic solvent and a lithium salt.

10. The electrolyte according to claim 9, wherein The lithium salt is selected from one or more of inorganic lithium salts, carboxylic acid lithium salts, sulfonic acid lithium salts, imide lithium salts, methylated lithium salts, boric acid lithium salts, lithium oxalate salts, and fluorine-containing organic lithium salts.

11. The electrolyte according to claim 9 or 10, wherein The concentration of the lithium salt is 0.5M-2M.

12. The electrolyte according to claim 9, wherein The non-aqueous organic solvent includes one or more of carbonate compounds, carboxylate compounds, ether compounds, and sulfone compounds.

13. The electrolyte according to any one of claims 1 to 12, wherein: The electrolyte further includes a third additive, and the third additive is selected from one or more of a film-forming additive, a conductive additive, a flame retardant additive, an overcharge protection additive, and an additive for improving high and low temperature performance.

14. A battery, wherein: The electrolyte comprising any one of claims 1 to 13.

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