Rationally designed hierarchical ZnCo2O4/Ni(OH)2 nanostructures for high-performance pseudocapacitor electrodes

Abstract

Hierarchical ZnCo₂O₄/Ni(OH)₂ nanostructures on Ni foam were rationally designed and successfully fabricated through a facile two-step growth method. The ZnCo₂O₄ nanowires grown on Ni foam served as backbones to improve the electrical conductivity of redox active Ni(OH)₂ electrode materials, enhance the surface areas of electrode materials, and solidify the Ni(OH)₂ electrode materials onto Ni foam as a current collector. Ni(OH)₂ nanosheets were electrodeposited on ZnCo₂O₄ nanowires. The electrochemical performances of the hierarchical ZnCo₂O₄/Ni(OH)₂ nanostructures were measured. Their specific capacitance is 2826 F g⁻¹ at a current density of 2 mA cm⁻², the rate capability is 71.4% when the current density increases from 2 to 20 mA cm⁻², the cycling stability is 72% after 2000 cycles at a high current density of 10 mA cm⁻², and the high specific energy density is 166.7 W h kg⁻¹ at a current density of 2 mA cm⁻² in a two-electrode system.