Tailoring the Electrolyte/Electrode Interface with 18-Crown-6 and fluoroethylene carbonate for Controlled and Uniform Lithium Deposition

Abstract

Lithium metal is considered the top choice for anode materials due to its exceptionally high energy density (3860 mAh g-1). However, its practical use in lithium metal anodes (LMAs) is limited by significant dendrite growth and unstable interface between the anode and electrolyte. Herein, 18-crown-6 and fluoroethylene carbonate (FEC) were introduced as combined additives to improve the stability of the electrode/electrolyte interface and enhance long-term cycling performance. The presence of FEC promotes the formation of a LiF-rich solid electrolyte interphase (SEI), which guides lithium deposition and accelerates the transport of Li+ ions. Additionally, 18-crown-6 can eliminate “hotspots” during the lithium deposition and dissolution processes, leading to superior electrochemical performance. By incorporating 1wt% 18-crown-6 and 10vol% FEC, Li||Cu half-cells achieved an impressive average coulombic efficiency of 97%, while Li||Li symmetric cells demonstrated excellent stability for over 800 hours. When paired with LiFePO4, the Li||LFP full cell retained approximately 98% of its capacity and maintained a high average coulombic efficiency of 99% after 100 cycles at 0.5 C. This research underscores the vital role of 18-crown-6 and FEC in electrolytes, revealing a fresh strategy to reduce lithium dendrite formation in lithium-based energy storage systems.