Pseudocapacitance-Enhanced Mesoporous Carbon Produced by Stepwise Pyrolysis of Discarded Oil-Absorbing Aerogels

A significant quantity of oil absorbents is annually used for addressing oil spill incidents, yet limited attention has been devoted to repurposing these discarded materials in a high-value manner. Within this study, a waste utilization method was proposed for fabricating supercapacitor (SC) electrodes using recycled biomass-based aerogel oil absorbents. Biomass-based aerogels exhibited a three-dimensional cross-linked network architecture characterized by high porosity and large pore size, which enhanced electron conduction and provided sufficient channels for rapid ion transport, thereby ensuring effective contact between the carbon electrode and electrolyte. The crude oil adhering to the aerogel pore surfaces facilitated the disorder, enhanced surface wettability, promoted the mesopore formation during carbonization and activation, and induced pseudocapacitance of the carbon electrode through the effective oxygen-containing groups. Resultantly, the synthesized carbon electrodes demonstrated a substantial specific surface area (>2600 m2 g–1) and pore volume (>1.35 cm3 g–1). The electrode exhibited a specific capacitance of 323.9 F g–1 at 1 A g–1 in a three-electrode system. The assembled symmetric SC attained a specific energy density of 17.3 W h kg–1 at 350.2 W kg–1 in 6 M KOH and 48.8 W h kg–1 at 350.4 W kg–1 in 1 M tetraethylammonium tetrafluoroborate/propylene carbonate. The specific capacitance remained stable at 99% after 30,000 cycles in an all-solid-state electrolyte. In addition, the high-mass loading electrode retained its capacitance by up to 96.6% after 10,000 cycles in 6 M KOH. This study delivers an innovative approach for electrode material preparation for advanced energy storage devices utilizing discarded oil absorbents.