In Situ Surface Film Formed by Solid-State Anodic Oxidation for Stable Lithium Metal Anodes

Surface protection has drawn increasing attention in lithium (Li) metal batteries by simultaneously taking advantage of the uniform potential distribution and high conductivity, whereas tuning the composition of the protective film and improving the resistance at the interface of protective film/Li metal remain the challenges. Herein, a solid-state anodic oxidation strategy for preparing an in situ protective film for enhanced cycle life of Li metal anode is illustrated. The solid-state anodic oxidation of lithium metal is realized for the first time, and the method can be further modified for tuning the composition of the protective film for highly ionic conductive fluorine-rich interface. Surface electrodeposition simulations indicate the important role of the conductive protective film in increasing the uniform potential distribution on the Li surface. The as-prepared in situ fluorinated protective film efficiently suppresses the dendrite growth and promotes the cycling performance of the Li metal full cell in commercial ester electrolyte without any additive. This work opens up a new avenue for fabricating unique in situ protective films with controlled composition on Li surface for energy storage applications.