Nano-Nest Type Porous NiCo₂S₄@polyindole Core–Shell Array: Efficient Energy Storage Supercapacitor Device

Designing materials in appropriate nanoarchitectures can improve several electrochemical properties to yield power storage devices. Here an inorganic–organic core–shell nanostructure in an appropriate morphology has been designed to improve ion-transportation as well as ion diffusion mechanism for possible application in supercapacitor materials and eventually in a solid state supercapacitor. The NiCo₂S₄@PI core/shell electrode material shows high specific capacitance with a 92% contribution from surface-controlled process, due to the presence of dual active metal sites for ion adsorption. Consequently, the fabricated prototype asymmetric supercapacitor delivered a high specific capacitance with high energy density and power density. Additionally, the device exhibits an exceptionally high capacitance retention of 100%. The device’s performance under real-life conditions has also been demonstrated. This work significantly shows that surface morphology modification by adopting a core–shell architecture can substantially enhance the ion transport process and is an effective strategy to improve the overall electrochemical energy storage performance.