Abstract:
Supercapacitors have received considerable attention in energy storage devices over the past ten years due to their fast recharge capability, high power performance, long cycle life and environmental benign. Electrode material is one of the crucial factors defining the electrochemical performance of supercapacitors. Rational design and optimization of the structure of electrode materials is an effective approach to enhance their electrochemical performance. In this study, a simple galvanostatic electrodeposition method is developed to grow ZnO nanorod arrays on the carbon cloth(CC). A thin layer of metal-organic framework (MOF) is coated on the surface of ZnO via hydrothermal method, followed by carbonization in N
2 atmosphere at a high temperature for porous carbon layer to obtain ZnO/C composite nanorods. Subsequently, Ni(OH)
2 nanoflakes are deposited on the surface of ZnO/C to form three-dimensional ZnO/C/Ni(OH)
2 core-shell composite nanorod arrays on carbon cloth. The structure of Ni(OH)
2 is adjusted by changing electrodeposition time and the optimal time is determined. The structural, morphological and electrochemical properties of ZnO/C/Ni(OH)
2 are investigated. The hierarchical composite arrays may provide more electroactive sites, facilitate ion and electron transfer and thus result in remarkable electrochemical performance of the ternary composite electrode. The experimental results indicate that the ternary composite electrode material exhibites a high specific capacitance of 1 051.9 F/g at a current density of 1.0 A/g and still remains 644.5 F/g as the current density is increased up to 10 A/g, and good cycling stability (87.1% capacitance retention after 5 000 cycles at 5.0 A/g), demonstrating excellent electrochemical performance of ZnO/C/Ni(OH)
2 composite electrode. This facile method provides a new strategy for the design and application of metal oxides/porous carbon/metal hydroxides deposited on various substrates for advanced energy storage devices.