Hierarchical core-shell electrode with NiWO₄ nanoparticles wrapped MnCo₂O₄ nanowire arrays on Ni foam for high-performance asymmetric supercapacitors

Rational construction of MnCo₂O₄-based core-shell nanomaterials with distinctive and desirable architectures possesses great potential in the advanced electrode material of high-performance supercapacitors. Here, a new class of hierarchical core-shell nanowire arrays (NWAs) with a shell of NiWO₄ nanoparticles and a core of MnCo₂O₄ nanowires is reported, which can significantly improve the electrochemical energy storage properties of supercapacitors. The unique core-shell structure endows the MnCo₂O₄@NiWO₄ NWAs electrode with a high areal specific capacitance of 5.09 F cm⁻² at a current density of 1 mA cm⁻² and a superior cyclic retention of 96% after 5000 charge-discharge cycles, which are more preferable than those of MnCo₂O₄ NWAs electrode. More importantly, an aqueous electrochemical energy storage device (core-shell MnCo₂O₄@NiWO₄ NWAs as the positive electrode and active carbon as the negative electrode, MnCo₂O₄@NiWO₄//AC ASC) was assembled and shows a high energy density of 0.23 mWh cm⁻² at a power density of 2.66 mW cm⁻², and 0.09 mWh cm⁻² at 16.00 mW cm⁻², indicating hopeful potential for practical applications. This work highlights the significance of NiWO₄ as a shell for hierarchical core-shell nanostructures, which can further improve the electron transport characteristic of the electrode material, thereby achieving performance breakthroughs in energy storage devices.