Comparative Study of Individual and Mixed Aqueous Electrolytes with ZnFe₂O₄ Nano–flakes Thin Film as an Electrode for Supercapacitor Application

In the present work, ZnFe₂O₄ nano-flakes thin films are grown on stainless steel substrate using mechanochemical approach. The prepared thin films are characterized and used as working electrodes for supercapacitor application. Investigation for an ideal electrolyte is systematically carried out by comparing three aqueous electrolytes such as LiOH, NaOH, KOH (1 M) and their binary mixtures (1:1 v/v of 1 M each electrolyte) on the basis of their supercapacitive performances. Among the electrolytes, 1 M KOH is found to be an ideal electrolyte, which demonstrates higher specific capacitance (433 F g⁻¹), cycle stability (91 % retention up to 4000 cycles), energy density (86 Wh kg⁻¹), respectively. The binary mixtures of LiOH-NaOH, NaOH-KOH and LiOH-KOH electrolytes show relatively less specific capacitance of 106, 146 and 180 F g⁻¹, respectively. The use of mixed electrolytes and underlying factors affecting the performance are investigated in detail for the first time. The physical parameters such as conductivity, density, viscosity, contact angle and hydrated ionic radius of aqueous electrolytes influencing the specific capacitance of the ZnFe₂O₄ nano-flakes based electrode is studied.