Polar Mesoporous Carbon-Coated Hybrid Separator Enabling Reversible Anchoring of Polysulfides in Li-S Cells

Despite tremendous efforts to develop lithium-sulfur (Li-S) batteries as next-generation energy-storage systems, their commercialization has been hindered by critical challenges such as the polysulfide shuttle effect and poor cycling stability.In this study, polar mesoporous carbon (p-MC) featuring abundant polar functional groups and high porosity is synthesized via pyrolysis at 400 , and a functional hybrid separator is then fabricated by uniformly coating p-MC onto the surface of a polyethylene (PE) membrane to mitigate polysulfide diffusion toward the lithium anode.A Li-S cell incorporating p-MC-coated PE separator (p-MC/PE) is systematically compared with two control cells: one employing a conventional PE separator and the other utilizing a nonpolar mesoporous carbon-coated separator (n-MC/PE).Remarkably, the p-MC/PE cell exhibits twice the capacity retention, enhanced rate capability, and reduced self-discharge after 300 cycles compared with the control PE cell.In addition, the p-MC/PE cell retains 83.1% of its initial capacity after 300 cycles, significantly outperforming the n-MC/PE cell.The exceptional performance of the p-MC/PE separator is attributed to the strong polar-polar interactions between the lithium polysulfides and functional groups on the p-MC surface.The synergy between polar functional groups and well-interconnected mesopores facilitates the capture of polysulfides through both chemical interactions and physical confinement.