Single Atom‐Substituted Chalcogenides with Anion Vacancy Bonded on Graphene Nanotubes for Achieving “1+1+1>3” Synergistic Enhanced Sodium Storage

Abstract Developing distinctive composite anodes with multiple active components is critical for enhancing the charge storage capability of sodium‐ion hybrid capacitors (SIHCs). Herein, In single atom‐substituted SnS 2 with moderate sulfur vacancies in situ bonded on N‐doped graphene nanotubes (In─SnS 2−x @NG) is ingeniously engineered as a superior anode. Theoretical calculations and in situ/ex situ characterizations illustrate that the introduced Sn(In)─N interfacial bonds immensely strengthen composites integration and boost charge transfer, then In single atom substitution effectively elevates d band center and enhances Na + adsorption. Moreover, the sulfur vacancies reveal the bifunctional roles in accelerating Na + diffusion and reinforcing structural thermodynamics. These merits guarantee deeply reversible conversion‐alloying reaction and yield additional surface capacitive behavior of the In─SnS 2−x @NG anode, further realizing “1+1+1>3” synergistic enhanced sodium storage with ultrahigh reversible capacity (∼1211.8 mAh g −1 at 0.1 A g −1 ) and prominent rate performance of 417 mAh g −1 at 5 A g −1 . Additionally, a SIHC device with the In─SnS 2−x @NG anode and the activated carbon cathode exhibits the high energy/power density of 278 Wh kg −1 /10.0 kW kg −1 and long cycle lifespan, showing promising practical application. This work not only offers in‐depth insights for designing SIHCs anodes, but also paves the way on practical applications for Na + storage systems.