Facile solvothermal synthesis of Co1−xS@CNTs/AC nanocomposite as integrated electrode for high-performance hybrid supercapacitors

Abstract

Transition metal sulfides are considered attractive electrode materials for energy storage and conversion devices due to their excellent electrochemical activity, especially for cobalt-based sulfide with low-cost, high stability and high specific capacity. Herein, we successfully synthesized a novel nanocomposite of carbon nanotube and activated carbon co-modified non-stoichiometric cobalt sulfide (Co1−xS@CNTs/AC) by a facile solvothermal method. Benefiting from the positive effects of CNTs and AC materials on the growth and nucleation of Co1−xS materials, as well as the construction of carbon materials that facilitate fast ion/electron diffusion and transport channels, the as-fabricated optimal Co1−xS@CNTs/AC electrode exhibits a high specific capacitance of 656.51 F g−1 at 0.6 A g−1 and an excellent rate capability, showing significantly better electrochemical properties than bare Co1−xS, Co1−xS@CNTs, and Co1−xS@AC electrodes. Besides, the assembled Co1−xS@CNTs/AC//AC hybrid supercapacitor delivers an excellent energy density of 20.50 Wh kg−1 at a power density of 241.26 W kg−1, and a satisfactory cycling stability of 95.96% capacitance retention after 16,000 cycles at 80 mV s−1. These excellent electrochemical properties demonstrate that the integrated electrode material modified with carbon material is a promising candidate for desiring high-performance green energy storage devices.