Marrying a Non‐Flammable Phosphate Solvent with Lithium Nitrate: Novel Electrolyte for Intrinsically Safe and High Performance Lithium Metal Batteries

Abstract

Abstract The formation of lithium (Li) dendrites and deterioration of the mechanical integrity of Nickel (Ni)‐rich cathodes directly hinder the commercialization of high‐voltage Li metal batteries (LMBs) with Ni‐rich cathodes. Herein, a novel electrolyte was tailored by combining non‐flammable triethyl phosphate (TEP) solvent with easily‐synthesized lithium nitrate (LiNO 3 ) as the main salt and fluoroethylene carbonate (FEC) additive. The preferential electrochemical decomposition of LiNO 3 and FEC provides robust and conductive solid/cathode electrolyte interphase (SEI/CEI) layer on the surface of the anode/cathode, which can protect both electrodes effectively during long‐term cycling. Benefiting from the synergetic effect of LiNO 3 and FEC, NFE−LiNO 3 exhibited outstanding performances in the cells with LiNi 0.6 Mn 0.2 Co 0.2 O 2 (Li||NMC622) under high voltage (4.3 V), achieving an extremely high average efficiency of ∼100 % with an exceptional capacity retention of 90 % after 250 cycles. This study provides useful insights into the rational design of highly efficient, non‐flammable, and low‐cost electrolyte for long‐lasting high‐voltage LMBs.