Hexagonal-like NiCo2O4 nanostructure based high-performance supercapacitor electrodes

A novel approach of double hydroxide-mediated synthesis of nickel cobaltite (NiCo 2 O 4 ) electro-active material by the hydrothermal method is reported. The obtained NiCo 2 O 4 electro-active material displays the spinel cubic phase and hexagonal-like morphology. Thermogravimetry analysis confirms the thermal stability of the electrode material. The functional groups and phase formation of NiCo 2 O 4 have been confirmed by FT-IR and Raman spectral analysis. The modified NiCo 2 O 4 electrode exhibits the highest specific capacitance of 767.5 F g −1 at a current density of 0.5 A g −1 in 3 M KOH electrolyte and excellent cyclic stability (94 % capacitance retention after 1000 cycles at a high current density of 5 A g −1 ). The excellent electrochemical performance of the electrode is attributed to the hexagonal-like morphology, which contributes to the rich surface electro-active sites and easy transport pathway for the ions during the electrochemical reaction. The attractive Faradic behavior of NiCo 2 O 4 electrode has been ascribed to the redox contribution of Ni 2+ /Ni 3+ and Co 2+ /Co 3+ metal species in the alkaline medium. The symmetrical two-electrode cell has been fabricated using the NiCo 2 O 4 electro-active material with excellent electrochemical properties for supercapacitor applications.