Preparation of porous cadmium sulphide on nickel foam: a novel electrode material with excellent supercapacitor performance

Abstract

Large surface area, high electrical conductivity, and abundant channels have been recognized to favor faradic capacitors, but their realization at the same time by a facile preparation process is still a great challenge. Here, we synthesized porous cadmium sulphide freely standing on nickel foam (CdS/NF) via a one-step hydrothermal method which possesses high specific capacitance, good rate capability and outstanding cycling stability. The CdS/NF microspheres present pores with a mean size of ∼3 nm, resulting in fast diffusion of ions, facile transportation of electrons and high activity, which make great synergistic contributions to reversible redox reactions. In the resulting supercapacitors, a specific capacitance of 909 F g⁻¹ is achieved at a current density of 2 mA cm⁻² with excellent rate capability that 88% of the original capacitance is retained at 50 mA cm⁻². After 5000 charge–discharge cycles at current densities as large as 50 mA cm⁻², 104% of initial capacitance is maintained. Finally, asymmetric supercapacitors with a high energy density of 28 W h kg⁻¹ at a power density of 160 W kg⁻¹ were obtained.