Electrolyte and lithium-ion battery using the same

Abstract

The invention discloses an electrolyte and a lithium-ion battery using the same. The electrolyte comprises a non-aqueous solvent, a lithium salt and additives, wherein the additives comprise vinylenecarbonate, vinylethylene carbonate and fluoroethylene carbonate, and further comprises sulfonate and / or sulfate compounds containing silane functional groups, wherein the alkyl groups in the silane functional groups are independently selected from alkanes or olefins of which the number of carbon atoms is 1-3, or the alkanes or olefins of which the number of halogen-substituted carbon atoms is 1-3.The sulfonate or sulfate compounds can generate a dense and tough passivation film on the surface of a positive electrode material, effectively suppress the oxidation reaction in the system, and playa positive electrode protection role. And meanwhile, the compounds can synergize with other additives to form a dense and stable SEI film on the surface of a negative electrode, effectively prevent the reduction reaction of the electrolyte on the surface of the negative electrode and the deposition of transition metal, improve the interface between the negative electrode and the electrolyte, slowdown the secondary reaction of the electrode interface in a storage or circulation process, and further improve the battery performance.

Description

Technical field [0001] The invention belongs to the technical field of lithium ion batteries, and particularly relates to an electrolyte and a lithium ion battery using the electrolyte. Background technique [0002] With the increasingly serious environmental problems and energy crisis, new energy vehicles are increasingly sought after by the market and policies. However, consumer anxiety caused by insufficient cruising range has seriously hindered the promotion of new energy vehicles. In order to solve the problem of insufficient cruising range, the development of high-energy density power batteries is imminent. [0003] The application of high energy density active materials is one of the important directions for the development of high energy density power batteries. At present, the cathode materials used in lithium-ion batteries mainly include lithium cobalt oxide, lithium iron phosphate, and ternary materials. Lithium cobalt oxide has superior electrochemical performance an...

AI Technical Summary

Problems solved by technology

[0004] However, as the nickel content in the ternary material increases, the lattice stability of the material gradually decreases, and the lattice collapse is prone to occur at high temperature or during cycling, accompanied by the release of oxygen and the dissolution of transition metals.

This not only leads to the destruction of the structure of the positive electrode material itself, but also brings a series of side reactions

The released oxygen reacts with the electrolyte, consumes the electrolyte and causes the battery to bulge and deform

After the transition metal dissolves, it will migrate and deposit on the surface of the negative electrode, resulting in an increase in the surface resistance of the negative electrode and a decrease in the utilization rate, thereby deteriorating the performance of the battery

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