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

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.