The effect of ionic liquid-based electrolytes for dendrite-inhibited and performance-boosted lithium metal batteries

Abstract

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.