A New Strategy of Constructing a Highly Fluorinated Solid‐Electrolyte Interface towards High‐Performance Lithium Anode

Abstract Lithium fluoride (LiF)‐rich solid‐electrolyte interface (SEI) layers are reported as an effective method to suppress lithium dendrites growth and capacity fading for Li‐plating/Li‐stripping. Herein, a new pre‐fluorination strategy is proposed by constructing an MgF2 thin film on pristine copper foil via the magnetron sputtering. This MgF2 film proves a lithiophilic substrate and shows highly irreversible conversion reaction to LiF in the first cycle. The resulting uniform LiF‐rich dual‐layered SEI layer helps homogenize lithium ions flux, and remaining magnesium metal particles help reduce the overpotential of lithium nucleation, which regulates the behavior of Li‐plating/Li‐stripping. As a result, the half‐cells (with a fixed plating capacity of 0.5 mAh cm−2 at 0.5 mA cm−2) with the electrode after 3 min sputtering treatment show a long cycle life and a high average Coulombic efficiencies (98.3% for 600 cycles). This pre‐fluorination strategy paves an effective and facile way for the application of lithium metal batteries.