Preparation Of Lithium-ion Batteries Novel Electrolytes And Its Electrochemical Performance

Currently, LiPF6in a blend of alkyl carbonates is used as the electrolyte system in lithium-ion batteries, but LiPF6is easy decomposition. Therefore, exploring new salts is still a challenge.In this report, lithium salts, LiODFB and LiBF4, are simultaneously synthesized by an improved method, which is cheaper, simpler, more productive and more environmentally friendly than any previous method. The stability against oxidative decomposition for this novel electrolyte,0.9mol/L LiODFB-SL/DMS, is higher than5.5V, suggesting that it would be an alternative electrolyte for5V high-voltage lithium-ion batteries. When used in Li/MCMB and LiFePO4/Li cells,0.9mol L-1LiODFB-SL/DMS electrolyte exhibits not only excellent film-forming characteristics, but also stable cycle performance and rate performance.As the extension of the above research results, the oxalic acid groups in LiODFB iεreplaced by a sulfur-containing group,we report for the first time the preparation of novel lithium difluoro(sulfato)borale (LiBF2SO4) as a salt for the electrolyte of lithium-ion batteries. The key electrochemical properties of LiBF:SO4were systematically evaluated and comparatively studied with LiPF6. The electrolyte with1.0mol L-1LiBF2SO4in a mixed solvent of EC and DMC (1:1) showed good electrochemical stability, stable cycle performance, and satisfactory rate performance. Especially, it can help the formation of an effective and conductive SEI film. LiBF2SO4-EC/DMC electrolyte shows good thermal stability, excellent film-forming characteristic, stable cycling performance, and good rate performance at80℃.These work, set up practical application prospect of new electrolyte system, and provides guidance for the design, research and development of new lithium salt.