Core–shell structured CoNi2S4@polydopamine nanocomposites as advanced electrode materials for supercapacitors

Novel core–shell structured CoNi2S4@polydopamine nanocomposites have been successfully developed as advanced electrode materials for supercapacitors. The CoNi2S4 nanoparticles are tightly wrapped by polydopamine, forming a hierarchical core/shell network, which benefits the improvement of the electrochemical properties. The electrochemical performance of the as-prepared materials had been investigated by cyclic voltammetry and galvanostatic charge/discharge tests. Specific capacitances of CoNi2S4 and CoNi2S4@polydopamine are 425 and 725 F g−1 at 10 A g−1 respectively. Electrochemical impedance spectroscopy results suggest that the coating of polydopamine can reduce the charge transfer resistance and increase the diffusion rate of the electrolytic ion efficiently. The superior pseudocapacitive performance of CoNi2S4@polydopamine can be ascribed to the unique core–shell heterostructure and the combined contribution of the electrochemical active CoNi2S4 and the conductive polydopamine.