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.