Synthesis and electrochemical supercapacitive performance of nickel–manganese ferrite composite films

• Here first time, nickel–manganese ferrite NixMn1−xFe2O4 (x = 0.2, 0.4, 0.6, 0.8) were synthesized onto stainless-steel substrate using spray technique.
• NixMn1−xFe2O4 explored as electrode material for supercapacitor application.
• Maximum specific capacitance obtained is about 147.27 F g−1.

Thin films of sprayed nickel–manganese ferrite i.e. NixMn1−xFe2O4 (x = 0.2, 0.4, 0.6, 0.8) were synthesized onto stainless-steel substrate and envisaged for electrochemical supercapacitor application where surface morphology was influenced by ‘x’ factor; confirmed from the scanning electron microscopy digital photo-images and energy dispersive X-ray analysis, respectively. The spinel-type rice-like crystallites of NixMn1−xFe2O4 were 70–80 nm in lengths and 20–30 nm in diameters. Cyclic-voltammograms of NixMn1−xFe2O obtained for different ‘x’ values i.e. morphologies, were used to figure-out the change of the specific capacitance (SC) for different scan rates in 1 M KOH electrolyte. The 147, 120, 131, 185 F g−1 SC values for 0.2, 0.4, 0.6, 0.8 ‘x’ values were obtained at 5 mV s−1 scan rate. Electrochemical impedance spectroscopy measurements of NixMn1−xFe2O4 film electrodes were performed for knowing the charge transport kinetics where composite i.e. 0.4 and 0.6 ‘x’ valued electrodes confirmed least performance than 0.2 and 0.8 ‘x’ values which could be attributed to availability of number of the surface charges.