Recent Progress in Liquid Electrolytes for High‐Energy Lithium–Metal Batteries: From Molecular Engineering to Applications

Abstract

Lithium–metal batteries (LMBs) have garnered significant interests for their promising high gravimetric energy density (Eg) ∼ 750 Wh kg−1. However, the practical application of the LMBs is plagued by the high reactivity and large volume change during charging–discharging of the lithium–metal anode (LMA), seriously deteriorating the battery safety and cycle life. Great efforts have been devoted to tailoring the electrolytes to favor the Li–metal electroplating by uniformizing the deposition morphology and by suppressing the side reactions between electrolytes and LMA. The aggressive chemistries of both the LMA and its high‐voltage counterpart give new electrolyte components more opportunities, especially designing via molecular engineering. Here, a comprehensive and in‐depth overview of the scientific challenges, fundamental mechanisms, and particularly historical strategies of designing new molecules for electrolyte components including solvents, salts, and additives. Their important roles in tuning the Li+ solvation structure, interface composition, decomposition pathways, and the resultant electrochemical performance of LMBs are also presented. Finally, novel insights and promising research directions from the practical application viewpoints are proposed for future electrolyte designs for high‐voltage LMBs.