One-pot synthesis of Cu-doped Ni3S2 nano-sheet/rod nanoarray for high performance supercapacitors

Cu-doped Ni3S2 nano-sheet/rod array was directly grown on Ni foam by one-pot hydrothermal method. The density functional theory calculations demonstrated that Cu doping could introduce defect energy levels near Fermi level to enhance intrinsic electronic conductivity and electrochemical activity. The unique structure integrated the advantages of 1D nanorod for effective charge transport, 2D nanosheet for abundant active sites and mechanical stability. The results can contribute to the high rate performance and long cycle stability in the charge/discharge process. Additionally, the Cu doping content have important effects on morphology, structure, and electrochemical performances. The optimized Cu-doped Ni3S2 electrode exhibited about 3 times higher specific capacitance compared with the pristine Ni3S2 electrode at 10 A/g, and it showed capacitance retention of about 94.0% after 5000 cycles at 5 A/g. Further, the all-solid-state supercapacitor based on Cu-doped Ni3S2 electrode and an activated carbon electrode achieved a high energy density of 33.7 Wh/g at a power density of 850.1 W/kg.