Synergistic catalysis and confinement in clay MMT-based Fe₃O₄/C composite for ultra-stable Lithium-sulfur batteries

With the rising demand for high-energy-density storage, traditional lithium-ion batteries face limitations in meeting future performance requirements. Lithium‑sulfur batteries (LSBs), renowned for their high theoretical energy density and low cost, have emerged as a promising next-generation energy storage system. However, their commercialization is severely hindered by the shuttle effect, caused by the dissolution and migration of polysulfides (PS). In this context, functionalizing separators with abundant, environmentally benign clay minerals presents a low-cost and sustainable solution. To further enhance performance, this study focuses on a composite of montmorillonite (MMT), a typical layered clay, integrated with a Fe₃O₄-C system. This Fe₃O₄-C-MMT composite was coated on the surface of a polypropylene (PP) separator to create a multifunctional barrier. Leveraging the synergistic effects of MMT's dispersion, Fe₃O₄'s catalytic activity, and carbon's conductivity, the modified separator significantly improves battery performance. The resulting LSB delivered a high initial discharge capacity of 1207.7 mAh g^-1 at a current density of 0.2C and maintained 973.2 mAh g^-1 after 100 cycles, demonstrating significant enhancements in specific capacity and long-term cycling stability. This work provides a novel and efficient approach for the rational and targeted design of high-performance LSBs.