A fluorinated carbonate-based electrolyte for high-voltage Li(Ni0.8Mn0.1Co0.1)O2 lithium-ion cells

This work performed a comprehensive investigation on a fluorinated electrolyte (1 M LiPF6 in a 1:9 solvent blend, by mass, of fluoroethylene carbonate (FEC) and methyl (2,2,2-trifluoroethyl) carbonate (FEMC)) proposed by Im et al. [1]. The fluorinated electrolyte addicted with 3 wt% lithium difluorophosphate (LFO), named FF19+3LFO is found to demonstrate better cycling performance in high-voltage Li(Ni0.8Mn0.1Co0.1)O2 lithium-ion cells over the other researched electrolytes. The improvement of cells’ performance under high-voltage conditions is revealed to benefit from the robust CEI layers formed by FF19+3LFO, which can significantly enhance the electrode/electrolyte interface and restrain the side reactions between cathode materials and electrolytes. Moreover, the FF19+3LFO cells also illustrate more competitive performance than the conventional non-aqueous electrolyte based cells in the high-temperature storage tests, accelerating rate calorimetry (ARC) tests, nail tests, overcharge tests, and so on. In short, the electrochemical and safety features of high-voltage cells are effectively improved by FF19+3LFO. More concern into the fluorinated electrolyte is warranted for achieving the high-capacity and high-safety lithium-ion cells. •A robust CEI layer was formed by FF19+3LFO on the surface of cathode materials.•FF19+3LFO improves the cycling performance of NMC811 cells under high voltages.•FF19+3LFO improves the safety performance of NMC811 cells under abusive conditions.