One-pot solution coating of high quality LiF layer to stabilize Li metal anode

The high reactivity of Li metal anodes towards liquid electrolytes leads to an unstable and accumulated solid electrolyte interphase (SEI) film, which results in dendrite growth and low Coulombic efficiency (CE). Lithium fluoride (LiF) coating is considered as a reliable and dense SEI film to protect the reactive anode, however, the chemistry to form uniform, conformal and high quality LiF protection layer on Lithium metals remains as a major challenge. Here we develop a simple solution method to obtain LiF coating on Li metal anodes. We have discovered a chemical method to fabricate LiF coating via the in-situ reaction between metallic Li and polyvinylidene fluoride (PVDF)-dimethyl formamide (DMF) solution. Owing to the chemically and mechanically stable artificial SEI film, the LiF-coated Li anode delivers a better cycling performance than bare Li anode under various current densities in symmetrical cells. Stable cycling over 300 plating/striping cycles was achieved with LiF-coated Li electrodes under a high current density of 3 mA cm−2. The LiF coating also effectively suppresses dendrite formation and reduces side reactions between the metallic Li and the carbonate-based electrolyte. Therefore, this simple and low-cost method may benefit the future applications of the next generation Li metal batteries.