Stability Enhancement of Lithium–Sulfur Batteries Using Electrospun Separator/Electrolyte Membranes

To enhance the electrochemical utilization and stability of lithium–sulfur batteries, the cell components and configuration must be optimized. In particular, the cell must be designed to improve the unique conversion-type battery chemistry of lithium–sulfur batteries and address challenges related to material characteristics and engineering aspects, such as rapid active-material loss and severe sulfide deposition in cells with high-loading sulfur cathodes. Therefore, in this study, electrospinning technology is used to prepare a series of polymeric membranes with polyacrylonitrile (PAN) to block the fast diffusion of polysulfides and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to facilitate stable lithium-ion transfer, thereby enhancing the electrochemical performance. According to this progress, we use PAN as a backbone in a designed composite membrane to slow polysulfide diffusion, and PVDF-HFP is electrospun on both sides of the PAN module to improve the lithium-ion transfer and redox stability. This develops a novel sandwiched PVDF-HFP/PAN/PVDF-HFP (PH/P/PH) separator/electrolyte membrane that exhibits enhanced electrochemical utilization of 82%, efficiency of over 95%, and retention of 60% at a C/10 rate, along with long-term rate performance with charge/discharge rates of C/10 to C/3. These promising materials, electrochemical, and cell performances highlight the potential of the proposed electrospun separator/electrolyte membrane in promoting the development of optimized lithium–sulfur batteries and cell components.