FeCl 3 -modified carbon as an electrode material for supercapacitors: preparation, analysis, and electrochemical properties

The necessity to combat the effects of global warming has made the use of renewable energy sources essential. Much attention has been focused on utilizing various types of biomass that can provide high energy productivity and serve as an alternative to traditional fossil fuels. This study specifically aims to investigate the electrochemical properties of carbon materials obtained from plant-based raw materials after biofuel production by the carbonization of melon and citrus peels at 300 °C and chemical activation using FeCl3. It is established that chemical activation with FeCl3 at 700 °C has led to dehydration, degradation of the carbon matrix, and the development of a microporous surface. For a two-electrode electrochemical cell, the specific capacitance values at a discharge current of 50 mA are 196 F/g in an aqueous KOH solution and 78 F/g in TEABF4. Based on the impedance spectroscopy results, an equivalent electrical circuit has been modeled, revealing the energy storage mechanism at the carbon electrode-electrolyte interface, with a physical interpretation of each circuit element provided. Most importantly, the device remains stable with no capacitance loss after 1000 cycles. The research findings may contribute to expanding the use of biomass as a cost-effective electrode component for supercapacitors.