Synthesis Of Fluorine-Containing Ester Additive And Application In Lithium Ion Batteries

Lithium-ion batteries as a hot spot in new energy field, it has great significance to improve its performance. Currently, Synthesis and electrochemical properties of cathode and anode materials have been relatively mature and perfect, but electrolyte has few studies relatively. The electrolyte is an important part of the lithium ion battery, it is the ions conductor in the cathode and anode materials, it is also the bridge to connect cathode and anode materials. Its own performance and its relationship with the cathode and anode materials have significantly affect battery performance.In this paper, we used 1mol·L-1LiPF6/(EC+DMC +EMC)(1:1:1 by volume) as basic electrolyte, adding 5%(v/v) fluorine-containing ester into it as additive. The performance of lithium-ion battery and the effects of additive on electrode/electrolyte interface were researched by charge- discharge of constant current, cycle performance test of batteries, CV, EIS, SEM, FTIR, and so on. The results showed, adding 5%(v/v) fluorine-containing ester can control the resolve of the solvents in the electrolyte, because the formation of an excellent performance solid electrolyte interface(SEI) film on the surface of electrode which can decrease the impedance of the battery. As a result, the battery got satisfactory electrochemical property and cycle performance. Also, we raised one decomposition mechanism according to the component and structure analysis of SEI film. In a word, fluorine-containing esters can be used as a film-forming additive of lithium-ion battery.