Mixed Nickel-Cobalt-Molybdenum Metal Oxide Nanosheet Arrays for Hybrid Supercapacitor Applications

Mixed metal oxide nanomaterials have been demonstrated to be promising positive electrodes for energy storage applications because of the synergistic enhancement effects. In this work, nickel-cobalt-molybdenum metal oxide (NCMO) nanosheets with hierarchical, porous structures were directly developed on nickel foam (NF) through a hydrothermal method and ensuing annealing treatment. Electrochemical tests in three-electrode configurations revealed that the as-prepared NCMO nanosheets possessed high specific capacitance (1366 F g−1 at the current density of 2 A g−1), good rate capability (71.3% at the current density of 40 A g−1), as well as excellent cycling stability (89.75% retention after 5000 cycles). Additionally, a hybrid supercapacitor was assembled and achieved an energy density of 46.2 Wh kg−1 at a power density of 713 W kg−1. Based on the systematic analysis of microstructure, morphology, and element compositions, the excellent electrochemical performance of the NCMO nanosheets could be attributed to the mesoporous feature, desirable compositions, excellent mechanical and electrical contacts, and fast ion/electron transportation rates. This study shows that the NCMO nanosheets offer great potentials for application in supercapacitors.