Studies on electrochemical performances of novel electrolytes for wide-temperature-range lithium-ion batteries.

Wide-temperature electrochemical behaviors of sulfolane (SL) with lithium difluoro(oxalato)borate (LiODFB) are studied using dimethyl sulfite (DMS) and diethyl sulfite (DES) as mixed solvents, respectively. In LiFePO4/Li cells, LiODFB-SL/DMS and LiODFB-SL/DES electrolytes always exert several advantages over a wide temperature range, such as stable cycling performance and good rate performance. Besides, in Li/mesophase carbon microbead cells, these novel electrolytes respectively exhibit excellent film-forming characteristics at both +60 and -20 °C, such as the formation of a stable and conductive SEI layer. It suggests that LiODFB-SL/DMS and LiODFB-SL/DES electrolytes are alterative candidate electrolytes for wide-temperature-range lithium-ion batteries.