▎ 摘　　要

Poplar powder is a common natural biomass material, while graphite is recognized as a vital natural mineral. In this study, poplar powder was modified and blended with graphene oxide, then the blended sample was codoped with boron and nitrogen atoms. Subsequently, an electrode material for supercapacitors was prepared by one-step carbonization. By intercalating, carbonizing, and activating the modified biomass-graphene oxide composites, a supercapacitor electrode material with prominent electrochemical performance was obtained. The current density reached 0.5 A g(-1), the specific capacitance exceeded 437 F g(-1), the specific surface area and total pore volume reached 1186.1667 m(2) g(-1) and 1.347904 cm(3) g(-1), respectively, and the capacitance retention rate exceeded 97.8% after 3000 charge-discharge cycles. Moreover, symmetrical ultracapacitor assemblies could achieve relatively high energy densities of 8.6 Wh kg(-1) at 498 W kg(-1) and 6.9 Wh kg(-1) at 3096 W kg(-1).