Structural and chemical synergistic effect of NiCo2S4 nanoparticles and carbon cloth for high performance binder-free asymmetric supercapacitors

Abstract A facial solvothermal method is used to synthesize NiCo2S4 nanoparticles on carbon cloth (CC) to investigate the synergistic effect of transition metal sulfide and carbon substrates on the electrochemical performance in supercapacitors. The results demonstrate that the integrated binder-free NiCo2S4/CC electrode achieved a specific capacitance of 1379 F g−1 at 1 A g−1, and high rate capability of 82% when the current density increase to 50 A g−1, which is 13% and 35% higher than that of pristine NiCo2S4 counterpart. Detailed electrochemical kinetic analysis reveals that the proportion of surface capacitive effect of the hybrid electrode is higher than that of NiCo2S4 electrode at various scan rates due to the introduction of CC. CC substrate can provide a highway for electrolyte ions and electrons, facilitate the reaction kinetics, and shorten the diffusion distances for redox reaction, leading to improved performance of pseudocapacitive NiCo2S4. In addition, the as-fabricated asymmetric supercapacitors (ASC) based on NiCo2S4/CC//CNF electrodes demonstrate a high energy density of 41.28 W h kg−1 at a power density of 1564 W kg−1, along with long-term cycling performance and high rate stability.