Nonflammable LiTFSI-Ethylene Carbonate/1,2-Dimethoxyethane Electrolyte for High-Safety Li-ion Batteries

Developing a nonflammable electrolyte is an efficient strategy to eliminate fire hazards and improve battery safety. Electrolytes containing nonflammable phosphate solvents enhance battery safety to a certain extent, but their compatibility with electrodes remains an obstacle. Here, a nonflammable electrolyte based on carbonate solvent is designed to resolve this dilemma while guaranteeing battery performance. We demonstrate that a nonflammable electrolyte employing the popular film-forming solvent ethylene carbonate (EC) and 1,2-dimethoxyethane (DME) with 2.3 mol kg−1 lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) has excellent thermal stability owing to the unique solution molecule structure. What's more, the nonflammable electrolyte possesses excellent compatibility with both LiNi0.6Co0.2Mn0.2O2 and graphite electrode. The initial specific capacity and capacity retention rate of graphite/LiNi0.6Co0.2Mn0.2O2 punch cells employing this electrolyte are 169.3 mAh g−1 and 98.7% (after 50 cycles), respectively, which are comparable to those of cells employing traditional carbonate electrolytes. Besides, short-circuit test of the pouch cell suggests that the release of gases accompanied by decomposition of electrolyte under abuse conditions is effectively suppressed. All of these results show a promising prospect of this nonflammable electrolyte for application in high-safety Li-ion batteries.