Improving supercapacitive performance of CNTs/NiCo2S4 composites by interface regulation

Abstract Integrating metal sulfides with carbon materials is considered as one of effective approaches to meet the demand of high-performance electrochemical energy storage materials. In this paper, we emphasize the critical role of interface between NiCo2S4 and CNTs for supercapacitive performance of the hybrid structures. The CNTs/NiCo2S4 nanocomposites with three kinds of interfaces are prepared using a one-step hydrothermal method by adding the pristine CNTs, surface-oxidized CNTs and nickel-coated CNTs, respectively. Benefiting from the unique nickel interface structure that adequately realizes the effective utilization of the conductive CNTs owing to the homogeneous dispersion of CNTs throughout the matrix as well as the strong interface adhesion by a bridging role, the CNTs:Ni@NiCo2S4 nanocomposite exhibits a high specific capacity of 224.0 mAh g−1 at a current density of 1 A g−1. An asymmetric supercapacitor assembled by the CNTs:Ni@NiCo2S4 nanocomposite and activated carbon as positive electrode and negative electrode, respectively, exhibits a high energy density of 60.7 Wh kg−1 at a power density of 800 W kg−1 and an excellent cycling stability of 88% capacitance retention after 10,000 cycles at 10 A g−1. This work described herein provides a new strategy for development of high-performance energy storage materials.