Lithium metal has been considered to be the most promising anode material for the new generation of energy-storage system. However, challenges still stand in protecting lithium metal from spontaneous reactions with electrolytes and preventing the dendritic propagation, both of which would lead to undesirable decrease in Coulombic efficiency. Polysulfone (PSf) membrane with high rigidity and free-volume cavities of approximately 0.3 nm was employed to provide a stable interface on the surface of anodic electrode. The isotropic channels were constructed by the interconnected and uniformly distributed free volumes in the polymer matrix, and were expected to be swelled by solvent molecules and anions of lithium salt and to allow Li+ ions to pass through onto the electrode surface. As a result, dendrite-free morphology of deposited lithium was observed. The stabilized interface arose from the PSf film was verified by the promoted performances of Cu|Li cells and steady voltage polarization of Li|Li cells. The full cell with PSf coated anode exhibited excellent cyclability (85% capacity retention rate over 400 cycles at 1 C) and an outstanding rate capability (117 mAh g− 1 at 5 C). The beneficial performances were further verified by the EIS results. This work provides a new strategic idea to settle the dendritic problems of Li metal anodes.