Hierarchical spinel NiMn₂O₄ nanostructures anchored on 3-D nickel foam as stable and high-performance supercapacitor electrode material

A simple hydrothermal route has been used to synthesize NiMn₂O₄ nanostructures (NSs) on nickel foam. The electrochemical investigation shows how annealing temperature affects its supercapacitive properties. The NMO@500-Ni-foam electrode shows a high specific capacitance of 930 Fg⁻¹ at a constant scan rate of 5 mVs⁻¹ in 1 M KOH electrolyte. Additionally, the corresponding symmetric supercapacitor device (SSCs) has a superior cyclic span with 93.7 % capacitance retention even after 5000 cycles, excellent electrochemical performance with a specific capacitance of 72.9 Fg⁻¹, specific energy of 11 Whkg⁻¹, and specific power of 857 Wkg⁻¹. The exceptional results suggest that NiMn₂O₄ grown on Ni-foam might be a promising candidate for electrochemical energy storage applications.