A Safe Electrolyte Based on Propylene Carbonate and Non-Flammable Hydrofluoroether for High-Performance Lithium Ion Batteries

In this work, a safe electrolyte was formulated by mixing propylene carbonate with 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, in which fluoroethylene carbonate was used to improve the compatibility of electrolyte with graphite anode. It was found that this electrolyte showed high safety and good wettability to separator and electrodes, and its conductivity reached 5.04 mS cm−1 at 25°C. In particular, this safe electrolyte could well support graphite/LiCo1/3Mn1/3Ni1/3O2 full cells. Its rate and cycle performances at room temperature were close to those of a conventional electrolyte, and better cycle performance at elevated temperature (60°C) was obtained. Moreover, it also showed excellent low-temperature performance, and the cell could even operate at −40°C.