A novel hot-pressed electrospun polyimide separator for lithium-sulfur batteries

In this study, a novel electrospun polyimide (PI) nanofiber membrane used as the separator for lithium-sulfur battery was prepared successfully by different preparation processes. Compared with the polyolefin membranes, the PI nanofiber separator prepared via a hot pressing process in polyamic acid (PAA) membrane has outstanding thermal stability, high strength, and good ability to absorb and store liquid electrolyte. Importantly, benefiting from interconnected pore structure and abundant polar functional groups of polyimide macromolecule, the diffusion and loss of intermediate polysulfides in electrolyte can be suppressed from physical and strong chemical adsorption and interaction. In cycle testing, the capacity fade rate is only 0.08% per cycle and the discharge capacity remains 680 mAh g−1 after 200 cycles at 0.5 C, which indicates the special hot-pressed electrospun PI separators have a good cycle stability and a broad application prospect in lithium-sulfur batteries.