Ultrathin Al₂O₃-coated reduced graphene oxide membrane for stable lithium metal anode

Abstract: Lithium (Li) metal has been considered as the most attractive anode materials for Li-ion batteries (LIBs) due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase (SEI) and dendritic Li on the metal anode, however, hindered its practical application. Herein, to address the issues, a Li-free electrode with ultrathin Al₂O₃ coated on reduced graphene oxide (rGO) membrane that covers a Cu foil current collector was developed. The composite electrode exhibits excellent interfacial protection of lithium metal deposited between Cu foil and rGO electrochemically. Firstly, it affords good Li⁺ permeability from the electrolyte. Secondly, the ultrathin Al₂O₃ has sufficient mechanical strength to inhibit the penetration of Li dendrite. Li metal was observed uniformly deposited between rGO membrane and Cu collector, and stable cycle performance of Li plating/stripping with Coulombic efficiency of ~ 91.75% at the 100th cycle is achieved in organic carbonate electrolyte without any additives.