Sulfone-based electrolytes for high-voltage Li-ion batteries

Sulfone-based electrolytes have been investigated as electrolytes for lithium-ion cells using high-voltage positive electrodes, such as LiMn2O4 and LiNi0.5Mn1.5O4 spinels, and Li4Ti5O12 spinel as negative electrode. In the presence of imide salt (LiTFSI) and ethyl methyl sulfone or tetramethyl sulfone (TMS) electrolytes, the Li4Ti5O12/LiMn2O4 cell exhibited a specific capacity of 80 mAh g−1 with an excellent capacity retention after 100 cycles. In a cell with high-voltage LiNi0.5Mn1.5O4 positive electrode and 1 M LiPF6 in TMS as electrolyte, the capacity reached 110 mAh g−1 at the C/12 rate. When TMS was blended with ethyl methyl carbonate, the Li4Ti5O12/LiNi0.5Mn1.5O4 cell delivered an initial capacity of 80 mAh g−1 and cycled fairly well for 1000 cycles under 2C rate. The exceptional electrochemical stability of the sulfone electrolytes and their compatibility with the Li4Ti5O12 safer and stable anode were the main reason behind the outstanding electrochemical performance observed with high-potential spinel cathode materials. These electrolytes could be promising alternative electrolytes for high-energy density battery applications such as plug-in hybrid and electric vehicles that require a long cycle life.