Facile synthesis and capacitive properties of nickel–cobalt binary metal oxide nanoaggregates via oxalate route

Abstract Nickel cobalt binary metal oxide (NiCo 2 O 4 ) aggregates were synthesized by simple chemical co-precipitation technique using oxalic acid for supercapacitor electrodes. Additionally, bare nickel oxide (NiO) and cobalt oxide (Co 3 O 4 ) were synthesized by the same technique and their electrochemical behavior was studied comparatively along with two different combination of NiCo 2 O 4 . The structural and morphological studies revealed the formation of NiCo 2 O 4 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 NiCo 2 O 4 (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 NiCo 2 O 4 (Ni 0.5: Co 1) electrode exhibited good capacitance retention (∼81.5%) after 4000 charge/discharge cycles.