Facile solvothermal synthesis and high supercapacitor performance of NiCo2O4 nanorods

NiCo2O4 nanorod arrays were synthesized employing a facile low-temperature solvothermal approach, followed by post-calcination treatment. The structural, morphological and elemental characterizations were done by diffraction, microscopic and spectroscopic techniques. The prepared sample was studied as an active electrode material for supercapacitor application in 2 M KOH aqueous electrolyte. The cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectral (EIS) studies were carried out to know the electrochemical activity of the prepared material. From the CV study, a high capacitance value of 440 F g−1 was obtained at a scan rate of 5 mV s−1 in a 3-electrode method. Apart from high capacitance value, the prepared electrode depicted 94% initial capacitance retention value after 2000 charge-discharge cycles at a current density of 8 A g−1. The fabricated symmetrical supercapacitor depicted a high energy density of 12.6 Wh kg−1 and a high power density of 4003 W kg−1. This was attributed to the better electrical conductivity of NiCo2O4 nanorods.