X-Ray Irradiation-Induced Enhancement of Supercapacitive Properties of Bio-derived Activated Carbon

The rising global energy demand calls for the development of highly efficient energy storage devices, particularly supercapacitors with remarkable power density. Because of its high surface area, activated carbon (AC) is crucial as a supercapacitor electrode material. X-ray irradiation of AC leads to modifications in its surface chemistry by altering the sp2 hybridization of the surface carbons. In the current work, we present x-ray irradiation studies on the supercapacitive properties of AC prepared by adopting an oil wick lamp method using soot derived from waste soybean oil. The activated soot is irradiated at a dose rate of 16 mGy/s under a 60 kV x-ray source and investigated as an electrode active mass for an electric double-layer capacitor (EDLC). The device studies reveal that x-ray irradiation is crucial in determining the sample’s physisorption and energy storage properties. The irradiated sample demonstrates high specific power density (135.9 W kg−1) and specific energy density (3.2 Wh kg−1). The energy density of the irradiated AC soot electrode sample is nearly double that of AC, i.e., 3.2 Wh kg−1 versus 1.6 Wh kg−1, respectively, making it a potential candidate for efficient electrodes in EDLC devices. The internal resistance of the supercapacitor shows a reduction from 25.5 Ω to 24.1 Ω after irradiation, thereby increasing the electrode conductivity. The investigations in the current work reveal a significant enhancement of the energy storage capacity of x-ray-irradiated AC for high-performance supercapacitor devices. Moreover, the environmentally friendly methodology adopted to synthesize AC soot can help reduce environmental pollution and contribute to the development of sustainable energy storage devices.