Lithium metal has long been considered as an attractive anode material in lithium metal batteries due to its superior specific capacity compared to the existing graphite-based anode. However, stabilizing the lithium-metal anodes from uncontrollable lithium dendrite growth is still a critical challenge that limiting their practical applications. In this presentation, I will introduce an asymmetric design of polymer membrane with tailored pore structure in order to restrict the lithium dendrite growth while promoting the transport of lithium ions. Under the optimal conditions, we successfully fabricated polymer membranes with a bi-continuously nanoporous top layer with increasing pore sizes toward bottom surface. This unique structure provides the membranes exciting transporting properties including high ionic conductivity and high transference number. Additionally, the Li/LiFePO₄ battery tests demonstrate that the cell with asymmetric membrane outperforms the cell with commercial separator and symmetric membrane in terms of specific capacity, rate capability, and cycling stability, revealing a promising potential for applications in high-energy-density lithium metal batteries.