Hydrothermal induced novel CuCo2O4 electrode for high performance supercapacitor applications

A facile hydrothermal method has been used to synthesis of cubic CuCo2O4 nanoparticles by using two types of precipitate agents like oxalic acid and NaOH. XRD and TEM results suggest that spinel cubic structure of CuCo2O4 with space group of Fd(3)m. The N-2 adsorption-desorption results confirms that oxalic acid assisted CuCo2O4 sample shows high surface area (133 m(2)g(-1)) and lower pore size 8-10 nm compared with NaOH assisted CuCo2O4 sample (surface area = 110 m(2)g(-1) and pore size = 10-15 nm). The valance state of the sample was analyzed through XPS and the result suggests that the presence of mixed Co2+ and Co3+ in the CuCo2O4 spinel cubic system. Impressively, the electrochemical performance of the oxalic acid assisted CuCo2O4 electrode exhibits a maximum capacity of 765 mAhg(-1) at a specific current of 2 A/g and results in good long term cyclic stability of 95% capacitance retention after 2000 cycles. Moreover, it delivers a high energy density of 25 W h/kg at a power density of 450 W/kg. This could be due to more electroactive sites for faradic reactions emerging from the two metal ions, higher electronic/ionic conductivity and fast electrolyte transportation kinetics promoted by unique morphology.