Study On The Synthetic Process Of Several Electrolyte Additives For Lithium-Ion Batteries

Use of electrolyte additives is one of the most economic and effective methods for the improvement of li-ion battery performance. With the rapid development of the lithium battery industry, the research and development of new additives has become one of the most active fields in the lithium-ion battery research. In this paper, vinylene carbonate(1), fluoroethylene carbonate(2), prop-1-ene-1,3-sultone(3) and2,5-di-tert-butyl-1,4-dimethoxybenzene(4) were screened by according to the relevant literature, the sources of raw materials and the degree of difficulty of synthesis. The synthesis process of the above additives was studied from reaction temperature, reaction time, ratio of raw materials, and other aspects.The synthesis of vinylene carbonate was accomplished by chlorination of ethylene carbonate with chlorine gas to chloroethylene carbonate, which was dehydrochlorinated by means of triethylamine to1. The chlorination was carried under solvent-free conditions. The dehydrochlorination reaction was carried in dimethyl carbonate which was commonly used as the electrolyte solvent, that can prevent residual solvent cause harmful effects to the additive.2,3,4-tri-t-butylphenol was used as inhibitor, the yield of above two reactions was75.0%, higher than published in literature.The fluoroethylene carbonate was obtained by substitution of chloroethylene carbonate with anhydrous potassium fluoride. The security costs was reduced, and the production process was easy to control. PEG-800was used as phase-transfer catalyst, the yield was82.5%.The synthesis of prop-1-ene-1,3-sultone was accomplished by chlorination of1,3-propane sultone with chlorine gas to2-chloro-1,3-propane sultone, which was dehydrochlorinated by means of triethylamine to3. The reaction route was greatly shortened, the yield of above two reactions was72.7%.The2,5-di-tert-butyl-1,4-dimethoxybenzene was obtained by methylation of hydroquinone with dimethyl sulfate to1,4-dimethoxybenzene, which was alkylated by means of tert-butyl, the yield of above two reactions was77.1%.The above compounds were determined by GC or HPLC, and structures confirmed by IR, GC-MS, LC-MS and1H NMR.