V 2 CT x MXene/Porous Carbon Nanofiber Composite Interlayer for Enhanced Polysulfide Redox Kinetics in Lithium-Sulfur Batteries

The commercialization of lithium-sulfur batteries (LSBs) is severely hindered by the polysulfide shuttle effect and inherently slow sulfur redox processes. To address these challenges, we develop a V 2 CT x MXene/porous carbon nanofiber (PCNF) composite interlayer that simultaneously suppresses the shuttle phenomenon and promotes electrocatalytic activity. The V 2 CT x MXene/PCNFs heterostructure facilitates efficient interfacial electron transport, thereby enhancing conductivity and accelerating charge-transfer processes. In addition, V 2 CT x acts as an effective electrocatalyst for sulfur conversion, promoting reversible reaction pathways across both the liquid-solid transition of long-chain Li 2 S x species and the solid-phase conversion from Li 2 S 2 to Li 2 S. The synergistic combination of strong polysulfide anchoring and accelerated catalytic conversion enables the interlayer to regulate both the chemical confinement and kinetic pathways of LiPSs. Additionally, the interlayer induces a favorable three-dimensional Li 2 S nucleation behavior, preventing surface passivation and improving active-material utilization. Theoretical analyses further reveal the electronic interactions and catalytic pathways responsible for these improvements. As a result, LSBs incorporation the V 2 CT x /PCNF interlayer supports an initial discharge capacity of 1319.4 mAh g -1 at 0.1C and maintains 707.5 mAh g -1 at a high rate of 5C, showing markedly improved long-term cycling. Moreover, stable operation under high sulfur loading and low electrolyte conditions highlights the practical applicability of the designed interlayer. These results highlight an effective strategy to advance LSB performance and offer guidance for designing multifunctional interlayers for future high-energy storage technologies. KEYWORDS V 2 CT x MXene, Porous carbon nanofiber, Interlayer, Li-S battery, Sulfur redox kinetics Acknowledgement This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT)(No. RS-2023-00217581) and the Commercialization Promotion Agency for R&D Outcomes(COMPA) grant funded by the Korean Government(Ministery of Science and ICT). (RS-2023-00304768). Figure 1