CeSe₂@TiSe₂-C Coated Separators for Mitigating the Shuttle Effect in Lithium-Sulfur Batteries

Lithium–sulfur batteries (LSBs) present a promising alternative to lithium-ion battery technologies due to their high theoretical energy density and multielectron redox chemistry. However, their commercialization is hindered by challenges such as the polysulfide shuttle effect, sluggish redox kinetics, and rapid capacity degradation. In this study, we introduce a CeSe₂@TiSe₂-C composite, synthesized from Ti₃C₂Tₓ MXene, as an advanced separator coating to address these limitations. The composite incorporates catalytically active CeSe₂ and TiSe₂ within a conductive carbon framework, enhancing sulfur utilization, suppressing polysulfide diffusion, and accelerating electrochemical reaction kinetics. Under high sulfur loading (5 mg cm⁻²) and lean electrolyte conditions, the coated separator enables stable capacity retention of 404 mAh g⁻¹ after 100 cycles with nearly 100% Coulombic efficiency. These findings underscore the potential of CeSe₂@TiSe₂-C as a multifunctional separator coating, offering a viable pathway toward high-performance and long-cycle-life LSBs.