Design and Fabrication of Petal-Like NiCo₂O₄@NiMoO₄Core/Shell Nanosheet Arrys Electrode for Asymmetric Supercapacitors

Abstract

The integrated design and fabrication of novel petal-like NiCo2O4@NiMoO4 core/shell nanosheet arrys electrode through two-step different hydrothermal and annealing process, the unique core-shell structure is beneficial to the diffusion of ion and the transport of charge, furthermore, the integrated structure electrode fully utilizes the synergistic effect of NiCo2O4 as a core material and NiMoO4 as a shell material and exhibits excellent electrochemical performance. The optimized NiCo2O4@NiMoO4 electrode (4h) delivers 6.91 F cm−2 and 1974 F g−1 at 5 mA cm−2, the capacitance maintains 76% after 5000 cycles at 40 mA cm−2, Moreover, an asymmetric supercapacitor was assembled by utilizing NiCo2O4@NiMoO4 electrode (4h) and activated carbon (AC) as the positive and negative electrodes, the viable operating voltage can expand to 1.6 V and energy density can reach 47 Wh kg−1 at the power density of 0.4 kW kg−1, the asymmetric supercapacitor shows outstanding cycling stability since the capacitance maintains 87% after 4000 cycles at 5 A g−1. This prominent electrochemical performance mean NiCo2O4@NiMoO4 core/shell nanosheet arrays electrode will has a lot of potential applications in energy storage.