Co_3O_4-induced area-selective growth of Ni(OH)_2 cellular arrays for high-capacity supercapacitor electrode

摘要

Three-dimensional (3D) hybrids are very valuable in the construction of supercapacitor electrodes. Ni(OH)(2) cellular arrays were in-situ grown on nickel foam using Co3O4 nanosheets (NSs) as nucleating agent. The formation, microstructure and supercapacitance performance of the Co3O4/Ni(OH)(2) cellular arrays are systematically investigated. The Co3O4/Ni(OH)(2) arrays present an open cellular nanostructure with ultrathin Ni(OH)(2) walls. The Co3O4/Ni(OH)(2) prepared by hydrothermal reaction of 12 h delivers a super-high specific capacitance of 4396 F g(-1) at 1 A g(-1), above the theoretical capacitances of both the Ni(OH)(2) and Co3O4. Additionally, the Co3O4/Ni(OH)(2) electrode shows an excellent cycle performance by retaining 80.1 after 5000 cycles and a stable rate capability by decreasing 21.1 from 1 to 10 A g(-1). The assembled asymmetric supercapacitor reaches a large energy density of 32 Wh kg(-1) at 7999 W kg(-1) by Co3O4/Ni(OH)(2) as anode and reduced graphene oxides as cathode. The prominent high-capacity performance can be attributed to the cellular arrays, ultrathin hybrid NSs and synergetic reactions of the Ni(OH)(2 )and Co3O4. The proposed technology is also suitable for producing other multi-component oxide/hydroxide arrays as electroactive materials for energy storage devices.