Toward the Sustainable Lithium Metal Batteries with a New Electrolyte Solvation Chemistry

Abstract

AbstractHerein, a new solvation strategy enabled by Mg(NO3)2 is introduced, which can be dissolved directly as Mg2+ and NO3− ions in the electrolyte to change the Li+ ion solvation structure and greatly increase interfacial stability in Li‐metal batteries (LMBs). This is the first report of introducing Mg(NO3)2 additives in an ester‐based electrolyte composed of ternary salts and binary ester solvents to stabilize LMBs. In particular, it is found that NO3− efficiently forms a stable solid electrolyte interphase through an electrochemical reduction reaction, along with the other multiple anion components in the electrolyte. The interaction between Li+ and NO3− and coordination between Mg2+ and the solvent molecules greatly decreases the number of solvent molecules surrounding the Li+, which leads to facile Li+ desolvation during plating. In addition, Mg2+ ions are reduced to Mg via a spontaneous chemical reaction on the Li metal surface and subsequently form a lithiophilic Li–Mg alloy, suppressing lithium dendritic growth. The unique solvation chemistry of Mg(NO3)2 enables long cycling stability and high efficiency of the Li‐metal anode and ensures an unprecedented lifespan for a practical pouch‐type LMB with high‐voltage Ni‐rich NCMA73 cathode even under constrained conditions.