Interconnected and hierarchical porous carbon derived from soybean root for ultrahigh rate supercapacitors

Suffering from the stable intrinsic structure and strong cross-linking between cellulose, hemicellulose, and lignin, the strategy of directional editing of biomass pore structure is rare. Here, we develop a simple hydrothermal strategy to reconstruct the macroporous biomass precursor to obtain interconnected and hierarchical porous carbon. Benefiting from its interconnected and hierarchical micro/meso/macroporous structure, high mesopore ratio of 74%, large surface area of 2690 m2 g−1, and abundant surface heteroatom (O, N, S), the resulting carbon performs an ultrahigh capacitance of 328 F g−1 at 1 A g−1, outstanding rate performance with a high capacitance retention of 60% at 100 A g−1, as well as good cycle stability in two-electrode system in 6 M KOH. Importantly, the resulting carbon also exhibits high areal capacitance of 4.1 F cm−2 at 1 A g−1 under a high mass loading of 20 mg cm−2 due to the robust ion-transfer kinetics. Furthermore, superior energy densities of 46.7 Wh kg−1 at 622 W kg−1 and 25.8 Wh kg−1 at 27.3 kW kg−1 are achieved in neat EMIM BF4.