The Effect of Ionic Liquid-Based Electrolytes for Dendrite-Inhibited and Performance-Boosted Lithium Metal Batteries

Lithium (Li) metal battery (LMB) has become closely watched in recent years due to its high energy density. However, uncontrolled Li dendrites growth can bring about a series of problems, leading to reduced battery life and safety issues. In this work, we discover that an Ionic liquid (IL)-based additive, composed of N-methyl, propyl pyrrolidinium bis(fluorosulfonyl)imide ([PMP][FSI]) and Vinylene Carbonate (VC), can significantly improve electrochemical performances of LMBs when added into ether-based electrolytes. Compared with LMBs with electrolytes containing no additive, those containing the IL-based additives experience an increase in the cycle number by more than 200%, presenting high and stable coulombic efficiency (CE), low and stable polarization, suppressed Li dendrites, thin dead Li layer, and low resistance. We also carry out first-principles calculations to elucidate the synergistic effects of [PMP][FSI] and VC, which may enhance the cohesion between the Li and Oxygen (O) and improve the stability and flexibility of the solid electrolyte interface (SEI) film, leading to a significantly enhanced cycling performance. This study provides an important strategy for the future development of ionic liquid-based electrolytes for high performance LMBs.