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

Petal-like Ni(OH) 2 −MnO x nanosheets were fabricated by electrochemical cathodic co-deposition on carbon fiber paper from Mn 2+ /Ni 2+ 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 Na 2 SO 4 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 MnO x , 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.