A Bilayer Modified Separator of Polysulfone-Polyethylene Glycol Block Copolymer and Conductive Carbon Black for Use in Lithium-Sulfur Batteries

Highly efficient electrochemical energy storage systems are attracting increasing attention. Lithium-sulfur batteries are considered a promising next-generation rechargeable battery, with advantages of high theoretical energy density, high theoretical specific capacity, and low cost. Sulphated polyacrylonitrile (SPAN) cathode lithium-sulfur batteries solve the problem of polysulfide shuttle in traditional lithium-sulfur batteries through a unique “solid-solid” conversion mecha-nism. However, SPAN cathode lithium-sulfur batteries still have problems of poor conductivity, cathode volume expansion, and slow reaction kinetics. This paper designs a composite separator modified with a double layer of polysulfone polyethylene glycol block copolymer (PSF-b-PEG) and conductive car-bon black (Super P) for use in SPAN cathode lithium-sulfur batteries to homogenize lithium-ion transport, enhance ion migration, improve the utilization rate of active materials, and enhance the electrochemical performance of the battery. The battery equipped with a SPAN cathode and an SP/PSF-b-PEG/PVDF compo-site separator achieved a discharge specific capacity of 423 mAh g−1, and retained 82.2% of its capacity after 500 cycles, with a single-cycle decay of only 0.0356%. At a high temperature of 60 °C, the battery also achieved 500 cycles at 1 C, with an initial dis-charge specific capacity of 447 mAh g−1, cycle retention rate of 75.3%, and a single-cycle decay of only 0.049%.