CN-116344941-B - Electrolyte and battery

CN116344941BCN 116344941 BCN116344941 BCN 116344941BCN-116344941-B

Abstract

The invention discloses an electrolyte and a battery, wherein the electrolyte comprises electrolyte salt, a solvent, a first additive and a second additive, the first additive is shown in a structural formula (1), and the second additive is selected from at least one of the structural formulas (2) and (3). The first additive can form a film on the interface of the positive electrode and the negative electrode, the interface of the positive electrode is oxidized to generate a stable fluorine-phosphorus-based interface film, the interface film has low impedance and high stability, the surface stability of the positive electrode is improved, the side reaction between electrolyte and active materials is restrained, the film formed on the negative electrode side of the first additive is lagged compared with the conventional additive, the second additive has lower LUMO orbit, the stable interface film is easy to generate on the negative electrode, more conjugated double bonds are more abundant than the interface film generated by the conventional anhydride structure, the thermal polymerization is easy to generate under high temperature and limit working conditions, the interface stability is protected, and the difluoro phosphoric acid compound generated on the surface of the vinyl anhydride film has the characteristics of low impedance and high stability, and improves the cycle and low temperature performance while improving the high temperature safety performance of the battery.

Inventors

WANG HAI
LI SULI

Assignees

珠海冠宇电池股份有限公司

Dates

Publication Date: 20260508
Application Date: 20230428

Claims (6)

1. An electrolyte solution, which is used for the electrolytic solution, characterized by comprising the following steps: Electrolyte salt, solvent, first additive and second additive, The structural formula of the first additive is at least one selected from structural formulas (A1) to (A4), and the structural formulas (A1) to (A4) are as follows: A structural formula (A1), A structural formula (A2), A structural formula (A3), Structural formula (A4); the structural formula of the second additive is at least one selected from structural formulas (B1) to (B4), and the structural formulas (B1) to (B4) are as follows: a structural formula (B1), A structural formula (B2), A structural formula (B3), Structural formula (B4); The content of the first additive is 0.1-10% of the total mass of the electrolyte; The content of the second additive is 0.2-3% of the total mass of the electrolyte.
2. The electrolyte of claim 1, further comprising: And a third additive comprising at least one of fluoroethylene carbonate, ethylene carbonate, 1, 3-propane sultone, ethylene sulfate, methylene methane disulfonate, acrylonitrile, maleic anhydride, diethanol anhydride, succinic anhydride, succinonitrile, hexanedinitrile, ethylene glycol bis (propionitrile) ether, and hexane trinitrile.
3. The electrolyte of claim 2, wherein the third additive is present in an amount of 0.1-15% of the total mass of the electrolyte.
4. The electrolyte of claim 1 wherein the electrolyte salt comprises: at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis-oxalato-phosphate, lithium tetrafluorooxalato-phosphate, lithium bis-oxalato-borate, lithium difluorooxalato-borate, lithium tetrafluoroborate and lithium bis-fluorosulfonyl imide.
5. The electrolyte of claim 1, wherein the solvent comprises at least one of a carbonate and a carboxylate, the carbonate comprising at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate; the carboxylic acid ester comprises at least one of ethyl propionate, propyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, isopentyl acetate, ethyl acetate, methyl butyrate, ethyl n-butyrate and gamma-butyrolactone.
6. A battery, comprising: the electrolyte of any one of claims 1-5.

Description

Electrolyte and battery Technical Field The invention belongs to the technical field of batteries, and particularly relates to electrolyte and a battery. Background The lithium ion battery has the remarkable advantages of high energy density, long cycle life, wide use temperature range, high charging speed and the like, and is widely applied to the fields of 3C numbers, new energy automobiles, energy storage power stations, aerospace and the like. The electrolyte, as the blood of the lithium ion battery, plays a role in transporting ions in the lithium ion battery, and belongs to a crucial part. The current lithium ion battery basically uses carbonate organic solvent, has low stability at high temperature, has failed in thermal shock and overcharge and overdischarge environments, and causes serious combustion and even explosion of the battery, so that the high-temperature safety performance of the battery is reduced. Disclosure of Invention The embodiment of the invention aims to provide an electrolyte and a battery, which are used for solving the problem of low high-temperature safety performance of the battery. In a first aspect, an embodiment of the present invention provides an electrolyte, including: electrolyte salt, solvent, first additive and second additive, the structural formula of the first additive is structural formula (1): Wherein X is selected from alkyl of 1-5 carbon atoms, alkenyl of 1-5 carbon atoms, alkynyl of 1-5 carbon atoms, haloalkyl of 1-5 carbon atoms, haloalkenyl of 1-5 carbon atoms, haloalkynyl of 1-5 carbon atoms, nitrile of 1-5 carbon atoms or halonitrile of 1-5 carbon atoms; The structural formula of the second additive is at least one selected from structural formulas (2) and (3), and the structural formulas (2) and (3) are as follows: r1, R2, R3 and R4 are independently selected from one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 1 to 10 carbon atoms, an alkynyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 1 to 10 carbon atoms, a fluoroalkynyl group having 1 to 10 carbon atoms, a nitrile group having 1 to 4 carbon atoms or a fluoronitrile group having 1 to 4 carbon atoms. Optionally, the structural formula of the first additive is at least one selected from structural formulas (A1) to (A4), and structural formulas (A1) to (A4) are: optionally, the structural formula of the second additive is at least one selected from structural formulas (B1) to (B4), and structural formulas (B1) to (B4) are: optionally, the content of the first additive is 0.1-10% of the total mass of the electrolyte. Optionally, the content of the second additive is 0.2-3% of the total mass of the electrolyte. Optionally, the electrolyte further comprises: And a third additive comprising at least one of fluoroethylene carbonate, ethylene carbonate, 1, 3-propane sultone, ethylene sulfate, methylene methane disulfonate, acrylonitrile, maleic anhydride, diethanol anhydride, succinic anhydride, succinonitrile, hexanedinitrile, ethylene glycol bis (propionitrile) ether, and hexane trinitrile. Optionally, the content of the third additive is 0.1-15% of the total mass of the electrolyte. Optionally, the electrolyte salt comprises: at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis-oxalato-phosphate, lithium tetrafluorooxalato-phosphate, lithium bis-oxalato-borate, lithium difluorooxalato-borate, lithium tetrafluoroborate and lithium bis-fluorosulfonyl imide. Optionally, the solvent comprises at least one of a carbonate and a carboxylate, wherein the carbonate comprises at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate; the carboxylic acid ester comprises at least one of ethyl propionate, propyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, isopentyl acetate, ethyl acetate, methyl butyrate, ethyl n-butyrate and gamma-butyrolactone. In a second aspect, an embodiment of the present invention provides a battery including: the electrolyte described in the above examples. The electrolyte comprises electrolyte salt, a solvent, a first additive and a second additive, wherein the structural formula of the first additive is shown as a structural formula (1), and the structural formula of the second additive is at least one selected from the structural formulas (2) and (3). The first additive is a difluorophosphazene compound, the second additive is a vinyl anhydride compound, the difluorophosphazene compound can form a film at the interface of a positive electrode and a negative electrode, the interface of the positive electrode is oxidized to generate a stable fluorophosphoric base interface film, the interface film has the characteristics of low impedance, high stability and the like, cyano and P element can inhibit excessive metal from dissolving out, the surface stab