Porous petal-like Ni(OH)2−MnOx nanosheet electrodes grown on carbon fiber paper for supercapacitors

Petal-like Ni(OH)2−MnOx nanosheets were fabricated by electrochemical cathodic co-deposition on carbon fiber paper from Mn2+/Ni2+ solutions. For the nanosheet electrode incorporating 25% nickel, the specific capacitance of 344 F g−1 at a current density of 0.5 A g−1 with a cycling stability of 92.5% after 10,000 cycles was obtained in 0.5 M Na2SO4 electrolyte. A symmetric supercapacitor device assembled from this as-fabricated electrode demonstrated the energy density of 17.36 Wh kg−1 at the power density of 249 W kg−1 and 1.8 Wh kg−1 at 5.01 kW kg−1, respectively. It showed an excellent cycling stability with a loss of only 3.3% after 10,000 cycles at the current density of 5 A g−1. These remarkable electrochemical performances are attributed to that the nickel enhanced the robustness of the porous structure and the conductivity of the pristine MnOx, which facilitates the charge transfer and ion diffusion during the long time cycling. Our results suggest a great potential in developing energy storage devices from manganese oxide based electrodes by incorporating nickel in the lattice.