High electrochemical cycling performance through accurately inheriting hierarchical porous structure from bagasse

Nature provides perfect varying models of hierarchical porous structures, but it remains a great challenge to accurately transfer these models intact to laboratory through carbonization during processing. In this study we report a new class of carbon materials whose hierarchical porous structure is accurately inherited from bagasse through a process consisting of a hydrothermal treatment with thiourea at 180 degrees C and then carbonization at 800 degrees C. The resulting composite structure consists of nanopores, supermicropores and ultramicropores with a high specific surface area of 2419 m(2) g(-1). The treatment with thiourea not only results in N and S doping but creates many papillae of a few hundreds of nanometer in diameter on the tubular wall. As a supercapacitor electrode working at 1 A g(-1) in aqueous electrolyte, it shows a capacitance of 312 F g(-1) (125 F cm(-3)), with 69% retention even at a very high current density of 20 A g(-1). The material renders a good energy density of 11 Wh kg(-1) at a power density of 125W kg(-1) and shows good cycling stability, 99.7% of initial capacitance remained after 10,000 charge/discharge cycles. As a lithium ion battery anode, it exhibited capacity of 621 mA h g(-1) at 100 mA g(-1) and the capacity remained at 310 mA h g(-1) at 1000 mA g(-1).