Construction of MnO 2 /micro-nano Ni-filled Ni foam for high-performance supercapacitors application

The MnO 2 /Micro-nano Ni-filled Ni foam (MNFNF) hybrids were systematically studied as supercapacitor electrodes. Micro-nano Ni-filled Ni foam (MNFNF) was prepared via a facile NiC 2 O 4· 2H 2 O coating process on foam, followed by sintering treatment, and then employed as substrate for electrodeposition of MnO 2 . The morphology of the MNFNF substrate exhibited an obviously second-porous structure, deriving from dehydration, decarboxylation, and the lattice contraction occurred in the sintering treatment process of NiC 2 O 4· 2H 2 O. The structure of pores was irregular with 0.05~2 μm in diameter, and the pore walls were composed of nanoparticles with 200~500 nm in diameter. Such porous MNFNF not only provided a conductive network to enhance the charge transport and mass transfer in the electrochemical process but also achieved a large MnO 2 mass loading capacity. Electrochemical test showed the MnO 2 /MNFNF electrode exhibited a mass specific capacitance (SC) of 723.7 F g −1 and an areal specific capacitance of 1.16 F cm −2 at a current rate of 0.25 A g −1 . The asymmetric supercapacitor device based on the MnO 2 /MNFNF electrode and active carbon electrode could supply an energy density of 24.5 Wh kg −1 at the maximum power density of 4.4 kW kg −1 . Meanwhile, the supercapacitor device also exhibited a good cycling stability along with 93.2% specific capacitance retained after 5000 cycles. These results demonstrated that the MnO 2 /MNFNF electrode could be one of the potential electrode material for energy storage applications.