Lithium-ion battery electrolyte for high-voltage ternary positive electrode material system

Abstract

The invention provides a lithium-ion battery electrolyte for a high-voltage ternary positive electrode material system. The lithium-ion battery electrolyte comprises a non-aqueous solvent, lithium hexafluorophate and a functional additive; the functional additive comprises a cyclic anhydride compound, a lithium salt type additive and methylene methanedisulfonate; the general structural formula of the cyclic anhydride compound is as shown in the description, wherein R1, R2, R3 and R4 are independently selected from any one of hydrogen atom, fluorine atom, or straight chain or branched chain alkyl with the number of carbon atoms of 1-4. The cyclic anhydride compound used in the lithium-ion battery electrolyte is higher in reduction potential (the reduction potential of succinic anhydride is 1.50 V vs Li+ / Li) on the negative electrode surface, so that other components in the electrolyte can be preferably reduced into films in the first charging process of the battery, the formed SEI film is high in stability. The cyclic anhydride compound used in the lithium-ion battery electrolyte is capable of effectively improving the cycle performance and high-temperature performance of the battery; and compared with fluoroethylene carbonate, the cyclic anhydride compound has excellent high-temperature performance as well as capability of improving the cycle performance.

Description

Technical field [0001] The present invention relates to the field of lithium ion battery electrolyte, more specifically, the present invention relates to a high-voltage ternary cathode material system lithium ion battery electrolyte. Background technique [0002] In recent years, with the development of portable electronic equipment, power tools and electric vehicles, higher requirements have been put forward for the energy density of lithium-ion batteries. The current commercial lithium iron phosphate batteries and lithium cobalt oxide batteries are either restricted by energy density, or by cost and safety performance, and cannot meet the needs of large quantities of electric tools and electric vehicles for battery use. [0003] LiNi x Mn y Co 1-x-y O 2 Ternary cathode materials are considered to be the mainstream cathode materials for the new generation of lithium-ion batteries due to their advantages of low cost, good safety, and high gram capacity, and are a major research foc...

AI Technical Summary

Problems solved by technology

[0005] Among the commonly used high-temperature additives for lithium-ion battery electrolytes at this stage: 1,3-propane sultone (1,3-PS) and 1,4-butane sultone (1,4-BS) Additives still cannot effectively inhibit the gas production of high-voltage ternary batteries under high-temperature conditions; 1,3-propene sultone (1,3-PST) significantly inhibits high-temperature gas production, but it has too thick a film, the first charge and discharge The problem of large irreversible capacity and poor cycle performance

The Chinese patent with the publication number CN104332650A adopts the technical route of "methylene disulfonate + fluoroethylene carbonate" to prepare a high-voltage electrolyte for lithium-ion batteries with a high-nickel ternary cathode material system, fluoroethylene carbonate It has good negative electrode film-forming performance and can effectively improve the battery cycle, but its instability under high temperature conditions can easily cause battery gas production and serious loss of battery reversible capacity

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