Mechanistics of Lithium-Metal Battery Performance by Separator Architecture Design

Lithium (Li)-metal anode has attracted renewed research interest due to its high specific capacity and the lowest negative potential. However, Li-metal batteries have safety issues and severe capacity fading. In this study, we demonstrate a facile and effective technique by adding an anodic aluminum oxide nanostructured interlayer onto the commercial polypropylene separator (PP) to create a novel architecture (AP). It is found that AP-based symmetric Li-Li cells and Li-NCM523 cells exhibit enhanced cycling performance and delayed capacity decay. Furthermore, compared with the cells with PP, the cells with AP show reduced overpotentials and improved cycle stability at low temperatures and various current densities, implying the wide applications of the designed architecture. The superior performance of AP is ascribed to its high electrolyte retention, high mechanical strength, and precisely ordered architecture, which contribute to uniform Li nucleation and growth. This unique separator architecture provides mechanistic insights into the design of rechargeable lithium-metal batteries, which are aimed at high energy density and cycling stability.