Sulfur‐Induced Lattice Modulation and Charge‐Transport Enhancement in MnO 2 Nanowires for Hybrid Energy Storage

ABSTRACT In this study, sulfur‐modified MnO 2 nanowires (MnO 2 ‐S) were synthesized via a two‐step hydrothermal and solid‐state process and evaluated as battery‐type electrodes for hybrid supercapacitors. Transmission electron microscopy (TEM) and high‐resolution TEM confirmed morphological integrity, while structural changes induced by sulfur inclusion were observed at the atomic scale, suggesting surface reconstruction and altered interplanar spacing. Electrochemical studies demonstrated that the 70% MnO 2 ‐S electrode achieved a high specific capacitance of 807.5 F g −1 at 1 A g −1 and retained 52.6% of its capacitance at 10 A g −1 . The hybrid supercapacitor assembled with 70% MnO 2 ‐S as the cathode and activated carbon as the anode displayed a mixed pseudocapacitive/electric double‐layer capacitance behavior, delivering an energy density of 35.81 Wh k g −1 and a power density of 934.17 W kg −1 . Notably, the device showed good cycling stability up to 8000 cycles. Here, we managed to demonstrate how controlled sulfur incorporation simultaneously modulates the MnO 2 lattice, enhances ion/electron transport through defect‐assisted pathways, and stabilizes long‐term electrochemical performance, revealing a tunable structure–property relationship that has not been previously established for MnO 2 ‐S heterostructures. Thus, the synergistic effects between sulfur and MnO 2 nanostructures support their application as high‐capacity electrodes for next‐generation supercapatteries, combining Faradaic energy storage with fast charge–discharge kinetics.