A lithium ion battery electrolyte and a lithium ion battery

Abstract

A lithium ion battery electrolyte comprise a non-aqueous organic solvent, a lithium salt and an additive, wherein that additive comprises dicyclohexylcarbodiimide, amino compound and isocyanate compounds. In the technical scheme provided by the invention, the additive of the electrolyte of the lithium ion battery comprises dicyclohexyl carbodiimide, amino compounds and isocyanates, wherein dicyclohexyl carbodiimide assists amino compounds and isocyanate compounds to participate in film formation, By forming a chain or network polymer film on the surface of the positive and negative electrodesof the lithium ion battery which is insoluble in the electrolyte and has strong oxidation resistance and good toughness, the impedance of the battery is reduced, and the high-temperature cycling performance and the rate performance of the lithium ion battery are improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery electrolyte and a lithium ion battery. Background technique [0002] With the development of society and the advancement of science and technology, people have higher and higher requirements for the capacity per unit volume of lithium-ion batteries. A series of new high-capacity positive electrode materials such as modified lithium cobaltate, high-nickel ternary, and lithium-rich manganese have emerged. Health, high specific capacity is also accompanied by high battery operating voltage, the battery operating voltage ≥ 4.35V, even as high as 4.8V. However, for the conventional decorative film additives VC (vinylene carbonate) and PS (1,3-propane sultone), the film formation is unstable under the condition of ≥4.35V high voltage, and the SEI film (solid electrolyte Interface, SEI film, is a passivation layer covering the surface of the electrod...

AI Technical Summary

Problems solved by technology

The theoretical specific capacity of silicon anode material is 3572mAh / g, which has the advantages of high specific capacity, low working voltage and abundant reserves, etc. However, there is a crystal phase transition of silicon in the process of lithium deintercalation and accompanied by drastic volume change (greater than 300%) , leading to particle crushing and poor cycle stability, it is often used in combination with carbon

The stability of silicon-carbon composite materials is better than that of pure silicon, but with the increase of silicon content and the increase of unit gram capacity, its volume effect in the cycle process is gradually obvious, and repeated shrinkage and expansion cause the surface film of the electrode to rupture and regenerate, constantly consuming Lithium salts, solvents, thereby reducing the high-temperature cycle performance and rate performance of lithium-ion batteries

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