Lithium-ion battery and its electrolyte

Abstract

The invention provides a lithium ion battery and electrolyte thereof. The electrolyte of the lithium ion battery comprises a lithium salt, a non-aqueous organic solvent and a combined additive, wherein the combined additive is a cyclotriphosphazene derivative, ethylene sulfate (DTD) and fluoroethylene carbonate (FEC); the general molecular formula of the cyclotriphosphazene derivative is as shown in the specification; R1 and R2 are -NH2, -NHR, -N(R)2 or -OR respectively; R is alkyl; the lithium ion battery comprises a positive plate, a negative plate, an isolating membrane and the electrolyte; the isolating membrane is spaced between the positive plate and the negative plate; and the electrolyte is the electrolyte of the lithium ion battery. The lithium ion battery provided by the invention has good safety performance, high-temperature storage performance, high-temperature cycle performance and low-temperature discharge performance at high voltage.

Description

technical field [0001] The invention relates to the field of batteries, in particular to a lithium ion battery and its electrolyte. Background technique [0002] Studies in recent years have found that reactions also occur at the interface between the positive electrode active material of lithium-ion batteries and the electrolyte, which has a great impact on the electrochemical performance, thermal stability and safety performance of lithium-ion battery positive electrode active materials. etc. will have an important impact. Selecting excellent film-forming additives and using them in combination with lithium-ion battery electrolytes such as ethylene sulfate, propane sultone, and fluoroethylene carbonate can not only show the advantages of a single additive in some aspects, but also Improve its deficiencies in other aspects. However, once the electrolyte containing the above additives is used in a high-voltage (4.4V and above) system, it will show poor cycle performance an...

AI Technical Summary

Problems solved by technology

However, the Chinese patent application publication number CN102420340A published on April 18, 2012 discloses that hexa-trifluoroethyltrimeric phosphazene will participate in the formation of the SEI film on the surface of the negative electrode, which makes the formed SEI film unstable. In turn, the capacity of the lithium-ion battery decreases and the rate performance decreases, and in the subsequent cycle of the lithium-ion battery, the electrolyte components can be continuously reduced, resulting in a decrease in the cycle performance of the lithium-ion battery

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