NiCo2S4/carbon nanotube nanocomposites with a chain-like architecture for enhanced supercapacitor performance

Abstract

A novel type of NiCo₂S₄/carbon nanotube (NCS/CNT) nanocomposite has been successfully prepared via a simple refluxing route without any surfactant and template. SEM and TEM observations confirm that the as-obtained NiCo₂S₄/CNT nanocomposites exhibit a necklace-like architecture, in which the NiCo₂S₄ particles are threaded with CNTs. As electrode materials for supercapacitors, the nanocomposites deliver an obviously pseudocapacitive behavior enhanced by a synergistic effect. When the loaded amount of CNTs is 10 mg (NCS/CNT-10), the maximum specific capacitance reaches up to 2210 F g⁻¹ at 1 A g⁻¹ and the specific capacitance can be maintained at 1949 F g⁻¹ at 1 A g⁻¹ after 14 000 multi-rate charge–discharge cycles. By applying the NCS/CNT-10 composite as the positive electrode and activated carbon as the negative electrode, an asymmetric supercapacitor was fabricated with excellent electrochemical performance. Such a large enhancement of the electrochemical performance is attributed to the strong necklace-like architectures, which possess advantages such as high electric conductivity, good mechanical stability and excellent strain accommodation.