A nonflammable liquid electrolyte for lithium-metal battery

Lithium-metal batteries with high-energy density have been widely studied in the field of electric vehicles in recent years. However, the hazard of the conventional flammable liquid electrolyte causes serious safety concern and impedes their wide applications. New liquid electrolytes with improved safety-level, in terms of the ability to restrict the Li dendrite growth and the nonflammability are strongly desired. In this work, a new trimethyl phosphate (TMP)-based liquid electrolyte with lithium difluoro(oxalato)borate (LiDFOB) as additives is developed. The results show that this electrolyte can effectively restrict the Li dendrite growth and avoid catching fire. The Li//Li symmetric cell using such an electrolyte can be stably cycled over 200 h with a low overpotential as small as 0.02 V at a current density of 0.5 mA cm(-2) and an aerial capacity of 0.5 mAh cm(-2). The capacity retention of the LiFePO4//Li cell could reach similar to 100% after 160 cycles at 0.5 C.