Highly Porous Carbon Materials Based on Cicada Slough for Outstanding Supercapacitor Performance

The development of fast charging and discharging energy storage devices that are environmentally friendly has become the key to addressing both the issue of diminishing energy sources and the increasing demand for energy storage for societal development. Cicada slough (CS)-based porous carbon (CSC) with microporous and mesoporous coexistence was prepared using CS as a precursor material and KOH as an activator, which was activated at high temperature. The materials were characterized using scanning electron microscopy, x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, and N₂ adsorption–desorption test, and the electrochemical properties were tested under two-electrode and three-electrode setups, respectively. The synthesized CSC material grew in oxygen content, resulting in a specific surface area of 1013.49 m² g⁻¹ and an average pore size of 2.17 nm. Furthermore, this porous carbon material had rich pore structures and good electrical conductivity. Three-electrode tests were performed in a 6 M KOH electrolyte, and the materials presented a specific capacitance of 127.2 F g⁻¹ at a current density of 0.5 A g⁻¹, with a capacitance retention of 82.54% when the current density was increased to 5 A g⁻¹. The symmetric supercapacitor was fabricated using two pieces loaded with the same mass of CSC and 6 M KOH electrolyte, and achieved an energy density of 10.85 Wh kg⁻¹ at a power density of 500 W kg⁻¹, and the specific capacitance retention was 100% after 10,000 cycles at 5 A g⁻¹.