Facile synthesis and capacitive properties of nickel-cobalt binary metal oxide nanoaggregates via oxalate route
Nickel cobalt binary metal oxide (NiCo2O4) aggregates were synthesized by simple chemical co-precipitation technique using oxalic acid for supercapacitor electrodes. Additionally, bare nickel oxide (NiO) and cobalt oxide (Co3O4) were synthesized by the same technique and their electrochemical behavior was studied comparatively along with two different combination of NiCo2O4. The structural and morphological studies revealed the formation of NiCo2O4 with cubic crystal structure and micron sized porous aggregates with spherical nanoparticles of 20-100 nm diameters. The electrochemical characterization was performed using cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopy in 6 M KOH aqueous electrolyte. The fabricated NiCo2O4 (Ni 0.5: Co 1) electrode showed maximum specific capacitance value of 475 Fg-1 at 0.25 Ag-1 discharge current density and showed better energy density of 16.49 Whkg-1 and power density 10.6 kWkg-1 than other electrodes. Moreover, the NiCo2O4 (Ni 0.5: Co 1) electrode exhibited good capacitance retention (∼81.5%) after 4000 charge/discharge cycles.