Keywords Lithium metal battery Separator Polybenzimidazole membrane Spongy morphology 1. Introduction Nowadays, lithium-ion batteries (LIBs) have been widely applied in portable electronic devices, electric vehicles, and smart grids [1], [2]. The rapid development of LIBs puts forward higher request of the energy density. Lithium metal with high specific capacity and low reduction potential is considered the most promising anode and has been used in Li-S and Li-O2 batteries [3], [4], [5], [6], [7].