Hierarchical NiCo2O4@NiO core–shell hetero-structured nanowire arrays on carbon cloth for a high-performance flexible all-solid-state electrochemical capacitor

Abstract

A hierarchical NiCo₂O₄@NiO core–shell nanowire hetero-nanostructure has been successfully anchored on a carbon cloth conductive substrate by the stepwise design to fabricate the NiCo₂O₄@NiO/CC composite for a high-performance flexible all-solid-state electrochemical capacitor. The assembled capacitor exhibits improved pseudocapacitive performance because of the synergetic effect of each component. Impressively, based on the total mass of active material on both electrodes, a high gravimetric capacitance of 1792 F g⁻¹ at 5 mA cm⁻² is achieved for the final NiCo₂O₄@NiO/CC flexible capacitor, along with excellent rate capability and cycle performance (with the capacity retention of 87.5% after 5000 cycling). The outstanding electrochemical performances are attributed to its superstructure with significantly enhanced active-surface area, favorable morphological stability and convenient ion transport paths. These results clearly present a cost-effective and alterable method for fabrication of various core–shell nanostructures on flexible conductive substrates, which may bring new design opportunities of device configuration for energy-storage applications in future wearable electronics.