Non-flammable fluorobenzene-diluted highly concentrated electrolytes enable high-performance Li-metal and Li-ion batteries

Lithium-ion batteries with Ni-rich cathode and flammable carbonate electrolytes are breeding severe safety concerns which hinds their application in electric vehicles. Herein, by introducing the fluorobenzene (FB) with low-density and low-cost as a cosolvent and bridge solvents in triethyl phosphate (TEP)-based diluted high-concentration electrolytes (DHCEs) system, we design a non-flammable electrolyte with a special solvation structure containing internal-external flame retardants. This non-flammable electrolyte not only solves successfully the incompatibility problem of TEP-based electrolyte to the Li-metal anode (LMA) and the graphite (Gr) anode, but also ensures the stable cycling of Li||LiNi0.7Co0.1Mn0.2O2 (86% capacity retention after 120 cycles) and Gr|| LiNi0.7Co0.1Mn0.2O2 (75% capacity retention after 200 cycles) full cells. Such design opens up a new window for developing new electrolyte systems and building safer high-energy-density batteries.