Biomass-derived microporous carbon with large micropore size for high-performance supercapacitors

Large micropore with a pore size of 1-2 nm can allow high charge storage capability while ensure fast ions transport, which serves to improve the energy density of supercapacitors without sacrificing high power density. Herein, we report a large micropore dominant microporous carbon derived from a biomass waste, flaxseed residue from the edible oil industry, for high-performance supercapacitors. The reported material exhibits a large specific surface area of up to 3230 m(2) g(-1), and more than 70.1% of micropore volume is contributed by large micropores. The specific capacitance of the obtained material reaches up to 369 and 398 F g(-1) in KOH and H2SO4 electrolyte, respectively. Meanwhile, the assembled supercapacitor device based on the obtained material exhibits excellent rate and cycle performance. Over 92.7% of the initial capacitance is retained even under a large current density of 20 A g(-3) and the capacitance retention is more than 98.1% after 10000 times cycle in KOH electrolyte. The energy density of the assembled supercapacitor device reaches 61.2 Wh k g(-1) at a power density of 468.8 W k g(-1), and a high energy density of 43.5 Wh kg(-1) is retained at a large power density of 13.3 kW kg(-1) in ionic liquid EMIMBF4 electrolyte.