NiF2 as an efficient electrode material with high window potential of 1.8 V for high energy and power density asymmetric supercapacitor

We investigated NiF2 as an energy storage material in asymmetric supercapacitor together with activated carbon (AC) as the counter electrode. Cyclic voltammetry and galvanostatic charge-discharge profile are carried out to investigate the oxidation-reduction process and capacitive behavior of the NiF2 sample. The interfacial electron transport properties of the sample are also explored using Nyquist plots in two and three electrodes configurations of electrochemical impedance spectroscopy. A very high specific capacitance of 751 F/g is achieved at 1 A/g current density in three electrode system. Further, the asymmetric supercapacitor device based on NiF2//AC structure reveals high capacitance of 175 F/g at 1 A/g in the high window potential of 1.8 V. The fabricated device retained 93% of its initial capacitance after 1000 cycles at 3 A/g current density affirms high electrochemical stability of the device. Ragone plot depicts high energy density of 79.65 Wh/kg with power density of 1727.35 W/kg for 1.8 V window potential at 1 A/g current density. High electrochemical stability of NiF2 sample endures the tetragonal phase even after electrochemical measurement which can be more useful in recycling the electrode material for future recycled supercapacitor devices.