Rational Synthesis of Highly Porous Carbon from Waste Bagasse for Advanced Supercapacitor Application

The development of ultrahigh-surface-area biomass-based carbonaceous electrode materials is a major science and engineering challenge for high-performance supercapacitors. Here we present a type of highly porous carbon material derived from waste bagasse by the purposeful combination of hydrothermal carbonization with chemical activation. The obtained waste bagasse-based carbon materials not only exhibit a valuable hierarchically porous structure with a honeycomb-like texture but also have a very high specific surface area. The highest specific surface area reaches 3151 m2 g–1, which is superior to those of other bagasse-based porous carbons reported so far. Benefiting from the combination of hierarchical pore structure and well-developed porosity, such a type of carbon materials serves very well when used as electrodes in both 1.0 and 1.8 V aqueous supercapacitors. For example, the as-prepared carbon electrode gives a high capacitance of 413 F g–1 at 1 A g–1 and a satisfied cycling stability of 93.4% capacitance retention after 10000 cycles in 1.0-V aqueous supercapacitors. A remarkably high energy density of 22.3 Wh kg–1 at a power density of 220.9 W kg–1 can be achieved in 1.8-V aqueous symmetrical supercapacitors. These very attractive electrochemical performances enable this highly porous carbon to go far beyond many previously reported carbonaceous electrodes, which presents a great potential for bridging the electrochemical performance gap between conventional nonaqueous and aqueous supercapacitors and opens up new avenues to high-value materials from waste bagasse