A comprehensive investigation of the mixed electrolyte's role in the fabrication NiCoZn-LDH@Ni-Foam based asymmetric supercapacitor

Supercapacitors stand out due to their high specific capacitance, power density, longevity, and environmental friendliness. Nowadays, LDH is one of the most researched and used electrode materials for supercapacitors. This paper describes the one-step hydrothermal synthesis of Nickel-Cobalt-Zinc layered double hydroxide (NiCoZn-LDH) at 150 °C for 15 h. The XRD analysis verified the formation of the NiCoZn-LDH structure while the SEM investigation revealed the surface morphology. The electrochemical behavior of the NiCoZn-LDH was evaluated in a three-electrode configuration to study the performance of the half-cell. For elucidating the practical applications, a two-electrode system was constructed with activated carbon (AC) as the anode material and NiCoZn-LDH as the cathode material to create the asymmetric supercapacitor (ASC). The ASC has been studied in a mixed electrolyte of 6 M potassium hydroxide (KOH) and 0.01 M Potassium ferricyanide (K₃[Fe(CN)₆]), which showed better results compared to pristine 6 M KOH. With the highest energy and power densities of 24.51 W h/kg and 121.53 W/kg, the two-electrode system produces the maximum specific capacitance of 176.5 F/g at a current density of 0.3 mA/cm². Additionally, the electrodes show a remarkable coulombic efficiency of 100 % after 1000 cycles at the high current density of 5 mA/cm².