Effect of phosphate (anion) precursor on structural and morphology behavior of nickel phosphate thin films and its supercapacitive performance

Abstract In present work, reproducible and economic chemical bath deposition method is used to deposit nickel phosphate thin films on stainless steel substrate for supercapacitor application and effect of anion precursors on structure and morphology of prepared thin film is studied. Change in structure from crystalline to amorphous is observed in prepared thin films due to precursor variation. Also, microplate to microsphere like morphological alteration is observed with the same. The microsphere like morphology of amorphous nickel phosphate thin film electrode exhibits the highest specific capacitance of ~1031 F g−1 (specific capacity 114.6 mAh g−1) at 0.5 mA cm−2 current density. Its practical application is tested by preparing asymmetric supercapacitor device comprasing amorphous nickel phosphate thin film as positive electrode and reduced graphene oxide as negative electrode. Asymmetric device delivers highest specific capacitance of ~100 F g−1 at 6 mA cm−2 current density with energy density of 45.33 Wh kg−1 at a high power density of 1.5 kW kg−1 and offers 80% capacitance retention over 3000 cycles.