3D heterogeneous ZnCo2O4@NiMoO4 nanoarrays grown on Ni foam as a binder-free electrode for high-performance energy storage

Abstract

3D heterogeneous ZnCo2O4@NiMoO4 core-shell nanowire/nanosheets nanoarrays (3D ZnCo2O4@NiMoO4 NAs) grown on the conductive Ni foam substrate was successfully synthesized by a two-step simple water bath heating method. The prepared composites were characterized by XRD, FESEM, and TEM and were found to ZnCo2O4 nanowires acted as the core and the NiMoO4 nanosheets covered as the shell. Using as a supercapacitor electrode, 3D ZnCo2O4@NMioO4 NAs/Ni foam demonstrate a high specific capacitance 1912 F g−1 (at the current density of 1 A g−1) and excellent rate capability (55% initial capacity retention at 20 A g−1). Furthermore, the asymmetric supercapacitors constructed with the anode (carbon nanotubes/Ni foam) and the cathode (3D ZnCo2O4@NiMoO4 NAs/Ni foam) exhibit excellent performances in energy storage. This solid-state device shows high specific energy 57.5 Wh∙Kg−1(at specific power density of 900 W∙Kg−1) and high specific power 18000 W∙Kg−1(at specific energy of 30 Wh∙Kg−1) by broaden the potentials range from 0 V to 1.8 V. These superior results of 3D ZnCo2O4@NiMoO4 NAs mainly comes from the synergistic effect of 3D array microstructure of the conductive ZnCo2O4/Ni foam and the nanosheet structure of NiMoO4. The ZnCo2O4/Ni foam can provide facial routes for the transfer of the ions and electrons and the nanosheet structure is benefit for the intercalation-deintercalation processes of OH− ions in the NiMoO4. This work provides a new strategy for the preparation of high-performance supercapacitor electrode.