Using Triethyl Phosphate to Increase the Solubility of LiNO₃ in Carbonate Electrolytes for Improving the Performance of the Lithium Metal Anode

The investigation of novel electrolytes for lithium metal anodes has been conducted. Incorporation of LiNO 3 into lithium difluoro(oxalato) borate (LiDFOB) in ethylene carbonate (EC) and dimethyl carbonate (DMC) electrolytes results in a significant improvement in capacity retention and Coulombic efficiency. While the solubility of LiNO 3 is very low in common carbonate solvents (∼0.03 M), the use of triethyl phosphate (TEP) significantly increases the solubility of LiNO 3 and improves the capacity retention and Coluombic efficiency of lithium metal anodes. Ex-situ surface analysis of the cycled electrodes suggests that incorporation of LiNO 3 results in nitrogen containing species (NO 3 − , NO 2 − , and N 3 − ) in the solid electrolyte interphase (SEI) which is likely responsible for the performance enhancement.