Development of a symmetric supercapacitor using a novel NiCo2S4/CNT composite electrode with ultrahigh energy density

The study revolves around the fabrication of a symmetric solid-state supercapacitor device using a novel NiCo₂S₄/PVDF/CNT composite electrode. This device yielded a wide potential window of 1.5 V (-1.6 V to 0 or 0 to 1.5 V), an exceptional power density (PD) of 0.54 KW/Kg, an energy density (ED) of 64.53 Wh/Kg at 1 A/g, and a specific capacitance of 206.5 F/g. Additionally, a test of the device's longevity after 2500 cycles revealed a 54% capacitive retention. The reduction in stability is attributed to the depletion in active sites due to volume expansion of amorphous NiCo₂S₄, as observed from the EIS analysis.