High‐Performance Sodium‐Ion Capacitors With Kinetics‐Matched Characteristics Enabled by N/O/S‐Doped Homologous Carbon Electrodes Derived From a Single Precursor

ABSTRACT Sodium‐ion capacitors (SICs) offer high energy and power density with long cycle life, but developing kinetically compatible electrodes remains challenging. This work developed a simple and sustainable strategy to synthesize homologous carbon electrodes from the inner shells of durian husks (ISDH) for high‐performance SICs. Through a controlled carbonization process, the derived hard carbon anode (ISDHC) exhibits expanded interlayer spacing. N/O/S co‐doping effectively enhances the storage of sodium‐ions. Density functional theory (DFT) calculations reveal that the introduction of N/O/S modulates the adsorption energy of Na + at defect sites, reducing irreversible Na + adsorption by optimizing ion desorption. In situ electrochemical impedance spectroscopy (EIS), Raman spectroscopy, and X‐ray diffraction (XRD) characterizations confirm the structural stability of ISDHC‐800 and reveal a reversible Na + storage mechanism involving surface adsorption, intercalation, and pore filling, supported by favorable kinetics showing lower resistance during desodiation. After activation, the obtained ISDHAC material exhibits a high specific surface area and hierarchical pore structure. The assembled ISDHC‐800//ISDHAC SIC achieves an energy density of 107.1 Wh kg −1 and a power density of 11,343.6 W kg −1 , along with superior cycling stability. This work presents an eco‐friendly and cost‐effective approach to fabricate electrode materials for SICs from waste biomass, contributing to the development of advanced energy storage systems.