Abstract: Structural degradation of anodes and imbalanced reaction kinetics at cathode interfaces have persistently constrained the advancement of sodium-ion hybrid capacitors (SIHCs). This study addresses these challenges by rationally designing a CNT@CoN_x/Ti₃C₂T_x heterostructured composite, engineered via an interfacial energy band engineering strategy to amplify synergistic charge storage mechanisms. The nitrogen-doped bamboo-like CNT@CoN_x architecture, when integrated with two-dimensional Ti₃C₂T_x nanosheets, optimizes electrode/electrolyte interfacial dynamics by simultaneously enhancing electronic conductivity, establishing rapid Na⁺ diffusion pathways, and mitigating structural pulverization. Electrochemical evaluation in a three-electrode configuration demonstrates a specific capacity of 428 C/g at 0.5 A/g, with 83 % capacity retention after 8000 cycles at 5 A/g. The full SIHC device (CNT@CoN_x/Ti₃C₂T_x//AC) achieves an energy density of 120 Wh/kg and power density of 160 W/kg, maintaining 83.5 % capacitance retention through 10,000 cycles at 2.5 A/g. First-principles calculations corroborate these findings, revealing enhanced density of states near the Fermi level, strengthened adsorption energetics (-1.72 eV), and reduced Na⁺ diffusion barriers (0.30 eV), collectively validating the interfacial charge transfer superiority of the heterostructure. This work provides cutting-edge insights and ideas for developing high-performance SIHC anode composites prepared with interfacially enhanced effects.

Key words: Sodium-ion hybrid capacitors, Bamboo-like CNTs, Band engineering, Ti₃C₂T_x