NiCo2S4 nanoparticles anchoring on polypyrrole nanotubes for high-performance supercapacitor electrodes

To solve the inevitable aggregation and the low cycling stability of NiCo2S4 electrode materials, herein NiCo2S4 nanoparticles anchoring onto polypyrrole nanotubes were synthesized by a hydrothermal method. The obtained NiCo2S4/polypyrrole nanotubes composites exhibit a high specific capacitance of 1705 F g(-1) at 1 A g(-1), and remarkable rate performance of 747.6 F g(-1) at 20 A g(-1). Furthermore, the assembled asymmetric super capacitor using NiCo2S4/polypyrrole nanotubes as a positive electrode and activated carbons as a negative electrode delivers a high energy density of 52.5 Wh kg(-1) at a power density of 562.5 W kg(-1), and excellent cycling stability with 83.3% retention after 5000 cycles. The excellent electrochemical performance of NiCo2S4/polypyrrole nanotubes can be attributed to the high conductivity of polypyrrole nanotubes, and the key assistant effects of polypyrrole nanotubes which impede the aggregation of NiCo2S4 and improve the exposed active sites for redox reaction. The results demonstrate that NiCo2S4/polypyrrole nanotubes are a promising electrode material for supercapacitors.