A Hybrid‐Salt Strategy for Modulating the Li+ Solvation Sheathes and Constructing Robust SEI in Non‐Flammable Electrolyte Lithium Metal Batteries

The electrode interface determines the performance of an electrochemical energy storage system. Using traditional electrolyte organic additives and high‐concentration electrolyte emerging recently are two generally strategies for improving the electrode interface. Here, a hybrid‐salt electrolyte strategy is proposed for constructing the stable electrode interface. Through the solubilization effect of phosphate ester on LiNO3, a hybrid‐salts‐based non‐flammable phosphate ester electrolyte system (HSPE) with LiPF6 and LiNO3 as Li salts has been developed. By the strong interaction between NO3− and Li+, the Li+ solvation sheath and solvent behaviors have been modulated, thus the undesirable effects of phosphate ester are eliminated and a robust SEI is formed. Experimental results and theoretical calculations illustrate that NO3− as a kind of strongly coordinating anion can reduce the number of TEP molecules and lower the reduction reactivity of TEP. The reconfigured Li+ solvation structure allows the formation of an inorganic‐rich SEI on the electrode surface. As a result, in the designed HSPE, the average coulombic efficiency of lithium plating/stripping is increased to 99.12 %. This work explored a new approach to construct the electrode interface and addressing the poor interface performance issue of phosphate esters. A hybrid‐salt electrolyte strategy is proposed for constructing the stable electrode interface in non‐flammable electrolyte by modulating the Li+ solvation sheathes. Through introducing strongly coordinating anions, the Li+ solvation sheathes and solvent behaviors have been regulated, thus the undesirable effects of solvents are eliminated and a robust SEI is formed, which lead to the stable cycling of safe lithium metal battery.