Non-Flammable Ester Electrolyte with Boosted Stability Against Li for High-Performance Li metal Batteries

Abstract

In traditional non-flammable electrolytes a trade-off always exists between non-flammability and battery performance. Previous research focused on reducing free solvents and forming anion-derived solid-electrolyte interphase. However, the contribution of solvated anions in boosting the stability of electrolyte has been overlooked. Here, we resolve this via introducing anions into Li+ solvation sheaths using anions with similar Gutmann donor number (DN) to that of solvent. Taking trimethyl phosphate fire-retardant (DN = 23.0 kcal mol-1) and NO3- (DN = 22.2 kcal mol-1) as an example, NO3- is readily involved in the Li+ solvation sheath and reduces the polarity of solvent. This results in boosted stability of electrolyte against Li. The developed non-flammable electrolyte has low viscosity, high ionic conductivity and is low cost. The reversibility of Li-Cu cell was improved to 99.49% and the lifespan of practical LMBs was extended by > 100%.