Fluoroethylene carbonate as co-solvent for Li(Ni_0.8Mn_0.1Co_0.1)O₂ lithium-ion cells with enhanced high-voltage and safety performance

In the present work, a non-flammable electrolyte using fluoroethylene carbonate (FEC) and dimethyl carbonate (DMC) as solvent is investigated for high-voltage lithium-ion cells with Li(Ni_0.8Mn_0.1Co_0.1)O₂ cathode. The cells containing 1 M LiPF₆ in FEC/DMC (3:7, volume ratio, named FD37) perform significantly better cycling features than those with the traditional electrolyte under high voltages, i.e., 3.0–4.6 V. This may ascribe to the robust cathode electrolyte interphase layer formed by FD37 on the cathode surface, which effectively inhibits the decomposition of electrolytes and improves the stability of the electrode/electrolyte interface at high voltages. Furthermore, the cells addicted with FD37 show superior performance to the traditional electrolyte-based cells during the high-temperature cycling and storage. In addition, more advanced safety features are revealed by FD37 cells in several typical safety tests including as accelerating rate calorimetry (ARC) tests, nail tests, overcharge tests, etc. To summarize, the fluorinated electrolyte presented herein may bring fresh inspiration for the design of high-voltage and high-safety lithium-ion cells, more concern into it is warranted to complete a deeper understanding.