Synergistic enhancement of sodium-ion storage performance in WSe₂/Ti₃C₂T_x@C heterostructure anode via improved electronic conductivity and structural stability

AbstractDeveloping high-capacity conversion anode materials for sodium-ion batteries (SIBs) remains a challenging task for commercial application. Herein, we report a multicomponent composite electrode for SIBs by integrating WSe₂ nanosheets with Ti₃C₂T_x@C conductive framework. The structural analysis validates the successful fabrication of hierarchical WSe₂/Ti₃C₂T_x@C and strong interfacial coupling between each component. The fabricated ternary composite demonstrates significant improvement in its physiochemical properties and makes it highly desirable for promoting fast Na+ ion diffusion. The as-synthesized WSe₂/Ti₃C₂T_x@C composite delivered a high initial discharge capacity of 521.4 mAh g−1 with a coulombic efficiency of 89% and maintained an attractive discharge capacity of 390.8 mAh g−1 after 500 consecutive charge-discharge cycles at 0.1 A g−1, outperforming pristine WSe₂. Moreover, the composite maintained a remarkable rate capability of 256.2 mAh g−1 (5 A g−1) and regained nearly the same discharge capacity when the current density was reverted to 0.1 A g−1. Kinetics study confirms reduced charge transfer resistance (R_ct) and improved ion diffusion behaviour of WSe₂/Ti₃C₂T_x@C composite. Furthermore, the DFT calculation demonstrates the narrowing of the band gap and improved density of states near the Fermi level, complementing the notable electrochemical performance of the composite. The superior electrochemical performance of WSe₂/Ti₃C₂T_x@C demonstrates that the combination of different working mechanism electroactive materials is a feasible approach to design a composite electrode with synergistically improved electrochemical properties for next-generation SIBs applications.