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.