Fast Supercapacitors Based on Graphene‐Bridged V2O3/VOx Core–Shell Nanostructure Electrodes with a Power Density of 1 MW kg−1

Transition metal oxides (TMOs), with their very large pseudocapacitance effect, hold promise for next generation high‐energy‐density electrochemical supercapacitors (ECs). However, the typical high resistivity of TMOs restricts the reported ECs to work at a low charge–discharge (C–D) rate of 0.1–1 V s^?1. Here, a novel vanadium oxides core/shell nanostructure‐based electrode to overcome the resistivity challenge of TMOs for rapid pseudocapacitive EC design is reported. Quasi‐metallic V₂O₃ nanocores are dispersed on graphene sheets for electrical connection of the whole structure, while a naturally formed amorphous VO₂ and V₂O₅ (called as VO_x here) thin shell around V₂O₃ nanocore acts as the active pseudocapacitive material. With such a graphene‐bridged V₂O₃/VO_x core–shell composite as electrode material, ECs with a C–D rate as high as 50 V s^?1 is demonstrated. This high rate was attributed to the largely enhanced conductivity of this unique structure and a possibly facile redox mechanism. Such an EC can provide 1000 kW kg^?1 power density at an energy density of 10 Wh kg^?1. At the critical 45° phase angle, these ECs have a measured frequency of 114 Hz. All these indicate the graphene‐bridged V₂O₃/VO_x core–shell structure is promising for fast EC development.