Electrically conductive metal oxide-Assisted multifunctional separator for highly stable Lithium-Metal batteries

[Display omitted] •A niobium oxide is employed as a separator coating material against Li metal.•The niobium oxide coated separator can redistribute the localized Li ion.•Nitridation was performed on niobium dioxide to improve the electrical conductivity.•A nitrided niobium dioxide coated separator leads to the high cycle stability in LMB. Lithium (Li) metal anodes have received intensive attention owing to its high specific capacity and low redox potential. However, chronic issues related to dendritic Li growth have hindered the pragmatic use of Li-metal batteries (LMBs). As one of feasible approaches, depositing a functional material on the separator is an efficient strategy for improving the electrochemical stability of LMBs. In this paper, we report a functionalized separator, comprising a nitrided niobium dioxide (named as n-NbO2) and a polypropylene (PP) separator. It is identified that niobium oxide interact with metallic Li, resulting in redistributing the localized Li ion. The n-NbO2-coated separator with enhanced electrical conductivity promotes Li plating/stripping process, reinforcing the Li ion redistribution effect. Due to these properties, Li-Cu cells with the n-NbO2-coated separator show the most outstanding cycle stability with high Coulombic efficiency (CE) over 200 cycles.