High‐Entropy Engineering Reinforced Surface Electronic States and Structural Defects of Hierarchical Metal Oxides@Graphene Fibers toward High‐Performance Wearable Supercapacitors

Abstract Construction advanced fibers with high Faradic activity and conductivity are effective to realize high energy density with sufficient redox reactions for fiber‐based electrochemical supercapacitors (FESCs), yet it is generally at the sacrifice of kinetics and structural stability. Here, a high‐entropy doping strategy is proposed to develop high‐energy‐density FESCs based on high‐entropy doped metal oxide@graphene fiber composite (HE‐MO@GF). Due to the synergistic participation of multi‐metal elements via high‐entropy doping, the HE‐MO@GF features abundant oxygen vacancies from introducing various low‐valence metal ions, lattice distortions, and optimized electronic structure. Consequently, the HE‐MO@GF maintains sufficient active sites, a low diffusion barrier, fast adsorption kinetics, improved electronic conductivity, enhanced structural stability, and Faradaic reversibility. Thereinto, HE‐MO@GF presents ultra‐large areal capacitance (3673.74 mF cm −2 ) and excellent rate performance (1446.78 mF cm −2 at 30 mA cm −2 ) in 6 M KOH electrolyte. The HE‐MO@GF‐based solid‐state FESCs also deliver high energy density (132.85 µWh cm −2 ), good cycle performance (81.05% of capacity retention after 10,000 cycles), and robust tolerance to sweat erosion and multiple washing, which is woven into the textile to power various wearable devices (e.g., watch, badge and luminous glasses). This high‐entropy strategy provides significant guidance for designing innovative fiber materials and highlights the development of next‐generation wearable energy devices.