Perspective on Recent Advances of Functional Electrolytes for Lithium Metal Batteries

Lithium metal batteries (LMBs) have attracted extensive research interest because of their unparalleled electrochemical performances. Electrolytes, a critical component of batteries, play a pivotal role in promoting ionic and charge transport and forming a solid–electrolyte interphase (SEI). The solvation chemistry of electrolytes is closely related to the performance of LMBs and can be effectively manipulated by adjusting their components and structures. However, electrolytes with undesirable electrochemical properties can lead to fast capacity decay and even pose severe safety hazards in LMBs. Therefore, the development of high-performance electrolytes is critical for the advancement of LMBs. Typical electrolyte strategies for LMBs include high-concentration electrolytes (HCEs) and localized high-concentration electrolytes (LHCEs). In this review, we primarily focus on recent advancements in functional electrolyte design strategies. We provide a brief overview of the characteristics and commonalities of different electrolyte formulations. Additionally, electrolytes prepared on the basis of novel solvents are also summarized, which is a key method of achieving high performance for LMBs. Finally, inspiring methods to further optimize electrolyte compositions and structures for practical LMBs are also proposed.