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Fast one-pot microwave preparation and plasma modification of porous carbon from waste lignin for energy storage application

Chen, Weimin, Wang, Xin, Luo, Min, Yang, Pei, Zhou, Xiaoyan
Waste management 2019 v.89 pp. 129-140
capacitance, carbon, carbonization, cost effectiveness, energy, energy density, lignin, microwave treatment, oxygen, porosity, porous media, surface area, waste management, wastes, water vapor
Because the commonly used two-step approach (carbonization followed by activation) usually produces microporous carbons and requires a long production duration, obtaining a low-cost porous-carbon-based supercapacitor with both high energy density and rate capability is a challenge. Herein, a more cost-effective one-pot approach via microwave heating in humidified N2 combined with water vapor plasma modification is proposed to obtain lignin-based porous carbon with a hierarchical and oxygen-enriched structure. Humidified microwave heating can produce hierarchical porous carbon with a high specific surface area (SBET) of 2866 m2 g−1 and high mesopore content of 68.16%. Water vapor plasma modification not only results in a further development of the porosity with an increase in SBET by 11.6% but also results in the doping of oxygen (up to 33.43%). These characteristics ensure a high energy storage capacity and an excellent rate capability for the prepared supercapacitor, which exhibits the highest specific capacitance of 254.6 F g−1 at 0.5 A g−1 with a retention rate of 75.6% at 10 A g−1. The results of this study confirm the good feasibility of the one-pot preparation approach combined with plasma modification for the effective use of waste lignin for advanced energy storage applications.