A Hierarchical Hybrid MXenes Interlayer with Triple Function for Room‐Temperature Sodium‐Sulfur Batteries

Abstract Room temperature sodium sulfur (RT Na‐S) batteries with high theoretical energy density and low cost have recently gained extensive attention for potential large‐scale energy storage applications. However, the shuttle effect of sodium polysulfides is still the main challenge that leads to poor cycling stability, which hinders the practical application of RT Na‐S batteries. Herein, a multifunctional hybrid MXene interlayer is designed to stabilize the cycling performance of RT Na‐S batteries. The hybrid MXene interlayer comprises a large‐sized Ti 3 C 2 T x nanosheets inner layer followed by a small‐sized Mo 2 Ti 2 C 3 T x nanoflake outer layer on the surface of the glass fiber (GF) separator. The large‐sized Ti 3 C 2 T x nanosheet inner layer provides an effective physical block and chemical confinement for the soluble polysulfides. The small‐sized Mo 2 Ti 2 C 3 T x outer layer offers an excellent polysulfide trapping capability and accelerates the reaction kinetics of polysulfide conversion, due to its superior electronic conductivity, large specific surface area, and Mo‐rich catalytic surfaces. As a result, RT Na‐S batteries with this hybrid MXene interlayer modified glass fiber separator deliver a stable cycling performance over 200 cycles at 1 C with an enhanced capacity retention of 71%. This unique structure design provides a novel strategy to develop 2D material‐based functional interlayer for high‐performance metal‐sulfur batteries.