Universal FeCl₃-Activating Strategy for Green and Scalable Fabrication of Sustainable Biomass-Derived Hierarchical Porous Nitrogen-Doped Carbons for Electrochemical Supercapacitors

Cost-efficiency utilization of value-added, biomass-based carbon materials is essential for versatile electrochemical energy-related applications. Herein, we smartly devised a universal and ecofriendly FeCl3-activating methodology for scalable, high-yield fabrication of biomass-derived hierarchical porous N-doped carbons for supercapacitors. The underlying FeCl3-involved activating mechanism was reasonably put forward. The mushroom-derived porous N-doped carbon, as a typical FeCl3-activating example, was endowed with a large surface area of ∼1143.6 m2 g–1, high-fraction (∼66.3%) mesopores, high-content (∼3.1 at. %) N doping, and good wettability and exhibited even better electrochemical behaviors when compared to those activated by KOH and/or without activation, thanks to its innately structural/componental/surfacial superiorities. The resultant carbon electrode with a high loading of 5 mg cm–2 displayed competitive gravimetric/volumetric capacitances of ∼307.4 F g–1 (∼212.1 F cm–3) at 1 A g–1 in 1 M H2SO4, much better than those in KOH, mainly owing to extra pseudocapacitance. Moreover, the assembled symmetric devices yielded high energy densities of ∼6.6 (1 M H2SO4) and ∼62.6 Wh kg–1 (1 M (TEA)BF4/PC) at a high rate of 1.5 kW kg–1, and ultralong cycling performance. More significantly, the FeCl3-involved synthetic protocol is highly promising and general for other biomass-derived porous carbon materials toward advanced supercapacitors.