Fluoroethylene Carbonate Additives to Render Uniform Li Deposits in Lithium Metal Batteries

TLDR

Lithium metal is a promising alternative to graphite anodes for higher energy density, but dendrite growth during plating/stripping raises safety and lifespan concerns. The authors employ fluoroethylene carbonate additives to create a LiF‑rich solid electrolyte interphase that protects the lithium metal anode. The resulting FEC‑induced SEI is compact and stable, enabling uniform lithium deposition. The FEC‑protected anode achieves 98 % Coulombic efficiency over 100 cycles and, when paired with a high‑loading LiNi₀.₅Co₀.₂Mn₀.₃O₂ cathode, delivers an initial capacity of 154 mAh g⁻¹, demonstrating a high‑energy‑density Li metal battery.

Abstract

Lithium (Li) metal has been considered as an important substitute for the graphite anode to further boost the energy density of Li‐ion batteries. However, Li dendrite growth during Li plating/stripping causes safety concern and poor lifespan of Li metal batteries (LMB). Herein, fluoroethylene carbonate (FEC) additives are used to form a LiF‐rich solid electrolyte interphase (SEI). The FEC‐induced SEI layer is compact and stable, and thus beneficial to obtain a uniform morphology of Li deposits. This uniform and dendrite‐free morphology renders a significantly improved Coulombic efficiency of 98% within 100 cycles in a Li | Cu half‐cell. When the FEC‐protected Li metal anode matches a high‐loading LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NMC) cathode (12 mg cm −2 ), a high initial capacity of 154 mAh g −1 (1.9 mAh cm −2 ) at 180.0 mA g −1 is obtained. This LMB with conversion‐type Li metal anode and intercalation‐type NMC cathode affords an emerging energy storage system to probe the energy chemistry of Li metal protection and demonstrates the material engineering of batteries with very high energy density.