Effects of Electrolyte Substitution on the Electrochemical Performance of Spinel Nickel Manganese Oxide Nanostructures for Supercapacitor Applications

A facile hydrothermal method was employed to synthesize NiMn ₂ O ₄ (NMO) nanostructures (NSs) for application as electrode materials in high-performance supercapacitors. The synthesised NMO-NSs were characterised by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Electrochemical performance was evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 4 M KOH and 4 M LiOH aqueous electrolytes. The NMO@NF electrode exhibited a high specific capacity of 511 C g ^− 1 at a scan rate of 5 mV s ^− 1 in 4 M LiOH electrolyte. Furthermore, the electrode demonstrated excellent cyclic stability with less than 1% degradation after 2000 cycles. These results highlight the significant influence of electrolyte selection on the electrochemical performance of NiMn ₂ O ₄ -based supercapacitors.