A long/short-range interconnected carbon with well-defined mesopore for high-energy-density supercapacitors

Amorphous carbon derived from biomass unusually combines the merits of large specific surface area and abundant micropores, offering massive anchoring points for ion adsorption in electrolyte. Nevertheless, the short-range ordered structure in amorphous carbon hinders the fast electron transfer. Conversely, graphitic carbon with long-range ordered structure is beneficial for electron transfer. Thus, a low-cost strategy is required to marry hierarchical porous structure with long-range ordered structure, resulting in a long/short-range interconnected porous carbon and then leading to fast ion and electron transfer. Herein, we modified the solid-phase conversion process of biomass by employing the features of liquid-phase carbonization for petroleum asphalt. With the assistance of asphalt, the large specific surface area (> 2,000 m²·g^-1), high ratio of mesopores (ca. 60%) together with long-range ordered structure are in-situ created in as-made porous carbon. Thanks to the well configured structure in small scale, the as-made co-converted carbon can be operated in high-viscosity EMIMBF₄ electrolyte with a superior capacitance (315 F·g^-1@1 A·g^-1). Besides, the as-assembled symmetric supercapacitor can deliver a super-high specific energy of 174 Wh·kg^-1@2.0 kW·kg^-1. This work provides a new version for designing highly porous biomass-derived carbon with long/short-range alternating structure at molecular level.