Electrodeposited endeavour: Concentration-tuned nickel oxide nanostructures for high-performance supercapacitors

Herein we focused on synthesis of concentration modulated nickel oxide (NiO) nanosheets by simple and straightforward electrodeposition technique to investigate physicochemical properties and eventually electrochemical performance. Cubic and hydrophilic NiO nanosheets with optimum crystallite size, porosity and mixed Ni 2+ / Ni 3+ states show pseudocapacitive nature with excellent performance. It is observed that, 956.22 F/g specific capacitance at 5 mV/s scan rate. The diffusion controlled reaction kinetics during charging and discharging process shows 25.04 Wh/kg and 3.41 kW/kg energy and power density respectively. The optimized sample exhibits lower values for series and charge transfer resistance due to the conducting channel developed through interconnected nanoparticles. Moreover, electrochemical performance of liquid state symmetric supercapacitor device is measured. The overall study reveals electrodeposited NiO nanostructures are an ideal candidate for energy storage applications. • Electrodeposited NiO nanosheets with optimized structure. • Showcased 956.22 F/g at 5 mV/s, reflecting excellent pseudocapacitive behaviour. • Achieved 25.04 Wh/kg energy and 3.41 kW/kg power densities. • Low R S and R CT values enhance conductivity and improve electrochemical efficiency. • Symmetric device showed 266.86 F/g and 10.24 Wh/kg energy density.