A Halogen‐Free and Flame‐Retardant Sodium Electrolyte Compatible with Hard Carbon Anodes

For sodium-ion batteries, two pressing issues concerning electrolytes are flammability and compatibility with hard carbon anode materials. Non-flammable that sufficiently stable against have—to the authors’ knowledge—previously only been obtained by either use of high salt concentrations or additives. Herein, authors present a simple, fluorine-free, flame-retardant electrolyte which is compatible carbon: 0.38 m sodium bis(oxalato)borate (NaBOB) in triethyl phosphate (TEP). A variety techniques employed to characterize physical properties electrolyte, evaluate electrochemical performance full-cell batteries. The results reveal conductivity sufficient for battery operation, no significant self-discharge occurs, satisfactory passivation enabled electrolyte. In fact, mean discharge capacity 107 ± 4 mAh g−1 achieved at 1005th cycle, using Prussian white cathodes anodes. Hence, studied promising candidate