Nonflammable Electrolytes for Lithium Ion BatteriesEnabled by Ultraconformal Passivation Interphases

The approaches enhancing the energy density of lithium (Li)-ion batteries (LIBs) often push the batteries to their safety limit. Therefore, electrolytes that not only enhance electrochemical performances but also improve safety properties of LIBs are urgently needed for further development of LIBs. Although organic phosphorus-containing solvents have been used with organic carbonates to form flame-retarding or nonflammable electrolytes, their poor compatibility with the graphite anodes leads to fast capacity fade of LIBs. Herein we report a promising approach by formulating a nonflammable localized high-concentration electrolyte based on triethyl phosphate, ethylene carbonate, and a partially fluorinated ether. This electrolyte readily generates a robust solid electrolyte interphase on the graphite anode and a cathode electrolyte interphase on the LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode. As a result, this electrolyte shows good compatibility with both the graphite anode and the high-voltage cathode and enables long-term cycling stability of the graphite parallel to NMC811 cells. This work sheds new light in the development of nonflammable electrolytes for high-energy-density LIBs.