The rational construction of heterostructured electrode materials that deliver superior performances to their individual counterparts offers an attractive strategy for supercapacitors. Herein, we anchor low-crystalline nanostructured MnO2 onto soybean stalk-derived carbon matrix through chemical activation and subsequent hydrothermal reaction. The highly porous and conductive matrix can effectively enhance pseudocapacitive kinetics of nanostructured MnO2. Therefore, the obtained nanocomposite exhibits high specific capacitance (384.9 F g(-1) at a current density of 0.5 A g(-1)), great rate capability (185.0 F g(-1) at 20 A g(-1)), and superior cyclability (90.7% capacitance retention after 5000 cycles). Using this nanocomposite as the positive electrode material, an asymmetric supercapacitor (ASC) is assembled, and achieves high specific energy of 34.2 Wh kg(-1) and high specific power of 9.58 kW kg(-1). The results of this study demonstrate great potential of combining biomass-derived porous carbon with metal oxides. (C) 2018 Elsevier B.V. All rights reserved.