Preparation And Properties Of Nickel Hydroxide/nickel Oxide-based Materials For Supercapacitor Electrodes

The realization of high-efficiency energy storage is one of the greatest scientific and engineering challenges in the 21st century. In recent years, supercapacitors have attracted significant attention because of their high power density, long lifecycle (>100,000 cycles) and simple principle. However, low energy density and high cost have limited the further development of supercapacitors. To achieve a high energy density, one promoting approache is the development of new materials for supercapacitor electrodes. Metal hydroxide/oxide materials are promising electrode materials because of their high specific capacity, typically 2-3 times higher than that of carbon materials. In the paper, the effect of reaction time and ethylenediamine concentration to β-Ni(OH)2 morphology and electrochemical properties were studied,ZnCo2O4/NiO composites with high-performance were prepared by a two-step solution-based method, the formation mechanisms and capacitive behaviors of CRG/NCFH composites were investigated.β-Ni(OH)2 self-assembled microspheres with hierarchical structure were successfully prepared by a complexing-precipitation process at 100℃ for 3 h. Each microsphere was constructed with dozens of flakes, which are connected with each other. At the same time, we explored the influences of reaction time and ethylenediamine concentration to p-Ni(OH)2 morphology. A maximum specific capacitance of β-Ni(OH)2 was 892 F/g at the current density of 10 mA/cm2. Furthermore, β-Ni(OH)2 displayed a wonderful long cycle life with 9.8% specific capacitance decreased after 1000 cycles and superior power density of 8.9 kW/kg.We present a two-step solution-based method for the fabrication of ZnCo2O4/NiO composites on 3D macroporous nickel foam. The obtained ZnCo2O4/NiO composites displayed a max specific capacitance of 1180 F/g and outstanding cycling stability with 91%specific capacitance retained after 1000 cycles. The enhanced electrochemical properties can be attributed to the unique hierarchical architecture and a rational combination of two electrochemically active materials. Our growth approach offers a new and efficient technique for the design and synthesis of metal hydroxide/oxide composites that are promising for electrochemical energy storage.Evaporation-induced nickel-cobalt-Manganese hydroxide (NCMH) and Nickle-Cobalt-Ferric hydroxide (NCFH) hetero-oriented nanocrystalline walls on chemically reduced graphene oxide/nickel foams were presented by a feasible dip-dry method. The surface morphology, structure and capacitive behaviors of NCMH composites and NCFH composites were well investigated. Results revealed that electrochemical properties of CRG/NCFH composites were better than CRG/NCMH composites. CRG/NCFH composites had a high specific capacitance of 964 F/g at the current density of 5mA/cm2 and an excellent long cycle life with 82.2% specific capacitance retained after 1000 cycles.