Distinctive flower-like CoNi2S4 nanoneedle arrays (CNS-NAs) for superior supercapacitor electrode performances

It is imperative to develop new and efficient electrode materials intended for electrochemical energy storage to accomplish increasing energy demand. Ternary cobalt-nickel-sulfides have gained more attention for energy storage owing to their superior redox chemistry and higher electronic conductivity as electrode materials. Herein, distinctive flower-like CoNi2S4 nanoneedle arrays (CNS-NAs) have been efficiently synthesized on Ni-foam by a very simple hydrothermal method for superior supercapacitors (SCs) electrode performances. The formation of CNS-NAs was depended upon an anion-exchange reaction mechanism relating to the pseudo-Kirkendall effect. The morphology, structure, and physical/chemical properties of the resulting material were analyzed by SEM, TEM/HRTEM, BET, XRD, and XPS. The electrochemical performances in the three-electrode system were evaluated by CV, GCD, and EIS measurements. The as-synthesized CNS-NAs exhibited a higher specific capacitance value of 2300 F/g at a current density of 1 mA/g and excellent cyclic stability with 93.8% capacitive retention after 5000 charge-discharge cycles. Larger surface area, outstanding electrical conductivity, abundant active cites, and distinctive flower-like morphology with the outstanding structural stability of CNS-NAs could be the reasons for its significant effect on the charge transfer and storage which consequences the superior electrochemical performances. In brief, this work offers a cost-effective and facile method to synthesize a promising electrode material for the potential application of high-performance SCs.