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

A significant\nquantity of oil absorbents is annually used for addressing\noil spill incidents, yet limited attention has been devoted to repurposing\nthese discarded materials in a high-value manner. Within this study,\na waste utilization method was proposed for fabricating supercapacitor\n(SC) electrodes using recycled biomass-based aerogel oil absorbents.\nBiomass-based aerogels exhibited a three-dimensional cross-linked\nnetwork architecture characterized by high porosity and large pore\nsize, which enhanced electron conduction and provided sufficient channels\nfor rapid ion transport, thereby ensuring effective contact between\nthe carbon electrode and electrolyte. The crude oil adhering to the\naerogel pore surfaces facilitated the disorder, enhanced surface wettability,\npromoted the mesopore formation during carbonization and activation,\nand induced pseudocapacitance of the carbon electrode through the\neffective oxygen-containing groups. Resultantly, the synthesized carbon\nelectrodes demonstrated a substantial specific surface area (>2600\nm<sup>2</sup> g<sup>–1</sup>) and pore volume (>1.35 cm<sup>3</sup> g<sup>–1</sup>). The electrode exhibited a specific\ncapacitance of 323.9 F g<sup>–1</sup> at 1 A g<sup>–1</sup> in a three-electrode system. The assembled symmetric SC attained\na specific energy density of 17.3 W h kg<sup>–1</sup> at 350.2\nW kg<sup>–1</sup> in 6 M KOH and 48.8 W h kg<sup>–1</sup> at 350.4 W kg<sup>–1</sup> in 1 M tetraethylammonium tetrafluoroborate/propylene\ncarbonate. The specific capacitance remained stable at 99% after 30,000\ncycles in an all-solid-state electrolyte. In addition, the high-mass\nloading electrode retained its capacitance by up to 96.6% after 10,000\ncycles in 6 M KOH. This study delivers an innovative approach for\nelectrode material preparation for advanced energy storage devices\nutilizing discarded oil absorbents.