Study on synergistic effect and high temperature performance of dual-salts of LiTFSI and LiODFB in LiCoO2-based batteries

The strong corrosion behavior at the Al current collector restricts the application range of LiTFSI, despite its high stability against water and thermal. The adding LiODFB into LiTFSI-based electrolytes as a co-salt can successfully suppress the Al corrosion. However, the mechanism of the synergistic effect and electrochemical performance at high temperatures remains unclear. In this work, electrochemical tests and physical characterization of mixed lithium salts in different proportions were carried out at a high temperature of 45 °C, and it was concluded that LiODFB0.2-LiTFSI0.8-based electrolyte had the best electrochemical performance at 45 °C. The capacity retention rate of the battery after 200 cycles is 95%, that's due to the good film-forming property of LiODFB and the high thermal stability of LiTFSI. This work provides a universal electrolyte design strategy for designing stable and safe high-temperature electrolytes for the LiCoO2 cathode.