High performance asymmetric supercapacitor based on hierarchical flower-like NiCo2S4@polyaniline

Supercapacitors attract people's much attention nowadays due to the growing demand for high performance energy storage devices. As one of the most important components in supercapacitors, electrodes with high specific capacitance are extensively studied to obtain high energy density supercapacitor devices. In this work, NiCo2S4@polyaniline hierarchical structures on nickel foam are fabricated through proper amount of polyaniline deposit on the surface of NiCo2S4 using a facile electrochemical deposition method. The recombination of polyaniline shell provides additional reactive sites and enhances electron transportation. Therefore, the specific capacitance of NiCo2S4@polyaniline is significantly higher than that of bare NiCo2S4. The as-prepared sample demonstrates an outstanding areal capacitance of 9.28 F cm−2 at 5 mA cm−2 and great cycling stability at a high current density (61.64% capacitance retention at current density of 20 mA cm−2). Asymmetric supercapacitor device is fabricated with the NiCo2S4@ polyaniline as positive electrode and activated carbon as negative electrode. The device provides an energy density of 32.47 Wh kg−1 at a power density of 129.02 W kg−1 and the areal energy density achieves 1.01 mWh cm−2 at 4.01 mW cm−2.