Facile synthesis of CoNi2S4 nanoparticles grown on carbon fiber cloth for supercapacitor application

A facile one-step hydrothermal route has been developed to directly synthesize CoNi2S4 nanoparticles on carbon fiber cloth (CC) to study the synergistic effect of bimetallic sulfides and carbon substrate on the electrochemical performance of supercapacitor electrode. The integrated binder-free CoNi2S4/CC electrode possesses an outstanding specific capacitance of 1165 F g(-1) at 1 A g(-1), and excellent rate capacitance (75.3% retention at 10 A g(-1)) in a three-electrode system, which is 27.2% and 32.2% higher than that of pure CoNi2S4 electrode. Detailed electrochemical tests and results showed that the surface capacitance effect ratio of the CoNi2S4/CC electrode is higher than that of pure CoNi2S4 electrode because of the introduction of CC. The CC substrates can provide a channel for electrolyte electrons and ions to promote reaction kinetics and shorten the diffusion distance of the redox reaction, thereby improving the performance of the pseudocapacitor CoNi2S4. Besides, the assembled asymmetric supercapacitors based on CoNi2S4/CC electrode and reduced graphene oxide electrode displayed a high specific energy density of 33.2 Wh kg(-1) at 800 W kg(-1), remarkable electrochemical stability (87.1% retention after 10,000 circulations) and high rate stability.