Electrolyte of lithium ion battery

Abstract

The invention discloses an electrolyte of a lithium ion battery for improving the safety performance of the battery. The electrolyte comprises an organic solvent, a lithium salt dissolved in the organic solvent and an additive, the additive is dithiocyano alkane, the corresponding molecular formula of the additive is CNR1SSR2CN, R1 and R2 are alkane with the carbon atom number ranging from 0 to 4,or hydrogen atoms on the alkane are replaced by fluorine atoms, and the number of the replaced fluorine atoms is within 1-5. In the actual experiment process, the added dithiocyano alkane additive can form surface protective films on the surfaces of the positive electrode and the negative electrode of the lithium ion battery as a sulfur-containing substance, so that the co-intercalation of solvents is prevented under the conditions of battery formation, circulation and the like, and the side reactions are reduced. Meanwhile, the nitrile substance can inhibit gas production of the battery under a high-voltage condition, and can effectively solve the problem of gas expansion of the battery under high voltage when being used as an additive of the electrolyte of the lithium ion battery.

Description

Technical field: [0001] The invention relates to the technical field of electrolytes for lithium-ion batteries, in particular to an electrolyte for lithium-ion batteries that improves battery safety performance. Background technique: [0002] In order to increase the energy density of lithium-ion batteries, the charging voltage is constantly required to be increased. However, in the process of voltage boosting, materials such as positive electrodes, negative electrodes, and electrolytes will be abused, requiring continuous technical improvement and improvement. For the electrolyte, it is necessary to use special additives to protect the positive and negative electrodes, so as to ensure that the cycle performance of the battery will not be affected under the condition of voltage increase. [0003] Common additives such as succinonitrile SN, tris(trimethylsilane) phosphate TMSP, 1,3-propene sultone PST, 1,2-bis(2-cyanoethoxy)ethane DENE, etc. Membrane additives, common lithi...

AI Technical Summary

Problems solved by technology

However, although the above-mentioned additives have a certain film-forming effect in the use of the electrolyte, they still cannot solve the gas production, internal resistance, flatulence, and compatibility with the negative electrode during the battery cycle under high voltage (≧4.30V), or cannot Solve the problem of increasing the nickel content of the positive electrode and the compatibility of the positive electrode with the electrolyte, such as flatulence, the inability to exert the gram capacity, and fast cycle attenuation, etc.

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