Synergy of MXene with Se Infiltrated Porous N-Doped Carbon Nanofibers as Janus Electrodes for High-Performance Sodium/Lithium–Selenium Batteries

Metal–selenium (M–Se) batteries are considered promising candidates for next-generation battery technologies owing to their high energy density and high-rate capability. However, Se cathode suffers from poor cycling performance and low Coulombic efficiency, owing to the shuttle effect of polyselenides. Herein, it is reported the incorporation of Ti₃C₂T_x MXene onto Se infiltrated porous N-doped carbon nanofibers (PNCNFs) to construct free-standing Janus PNCNFs/Se@MXene cathodes for high-performance Na–Se and Li–Se batteries. The increase of pyrrolic-N content and the porous structure of the PNCNFs is conducive to enhancing the adsorption of Na₂Se and alleviating the shuttle effect. Meanwhile, density functional theory (DFT) calculations have proven that 2D Ti₃C₂T_x MXene with polar interfaces enables the effective chemical immobilization and physical blocking of polyselenides to suppress the shuttle effect. The unique architecture with Ti₃C₂T_x MXene built on top of interlinked nanofiber ensures the continuous electron transfer for redox reaction. As a result, the novel Janus PNCNFs/Se@MXene electrodes deliver robust rate capabilities and superior long-term cycling stability in both Na–Se and Li–Se batteries. The incorporation of 2D MXene to construct Janus electrodes provides a competitive advantage for selenium-based cathode materials and highlights a new strategy for developing high-performance batteries.