A sol-gel process for fabrication of NiO/NiCo2O4/Co3O4 composite with improved electrochemical behavior for electrochemical capacitors.

Transition metal oxides possess multiple oxidation states that enable rich redox reactions for pseudo capacitanc. They have been investigated as promising electrode materials to achieve high energy density. In this study, NiO/NiCo(2)O(4)/Co(3)O(4) composite with high specific surface and mesoporous structure is fabricated by a sol-gel process then calcined at 250 °C. Benefits from the improved electron conductivity and effective mesoporous structure, the fabricated composite exhibits high specific capacitance (1717 F g(-1)), enhanced rate capability, and excellent electrochemical stability (94.9% retention after 1000 cycles). Interestingly, the specific capacitance of the composite is higher than that of NiO, NiCo(2)O(4), and Co(3)O(4), which indicates a synergistic effect of the composite on improvement of electrochemical performance. The findings demonstrate the importance and great potential of NiO/NiCo(2)O(4)/Co(3)O(4) composite in development of high-performance energy-storage systems.