Regulating the specific surface area and porous structure of carbon for high performance supercapacitors

Abstract

The porous structure and specific surface area (SSA) of porous carbon are important factors affecting the performance of supercapacitors. However, it is still a great challenge to leverage the tradeoff between the SSA and mesopores to achieve both excellent capacitive and rate performance. Herein, we develop a facile pore- regulating strategy to integrate interconnected porous structure, large SSA and suitable mesopore volume in porous carbons. The co-pyrolysis of cotton stalks and oxidized coal can generate more defect sites, which is conducive to form a honeycomb-like morphology and reasonable porous structures in the following activation process. The integration of large SSA (1510 m2 g−1) and abundant mesopore volume (0.24 cm3 g−1) endow the optimal sample with a high capacitance (345 F g−1 @ 1 A/g), superior rate performance (69 % capacitance retention @ 50 A/g), and excellent long cyclic stability in 6 M KOH electrolyte. Moreover, the assembled symmetric supercapacitor exhibits a high energy density of 56 Wh kg−1 @ 741 W kg−1 in EMIM BF4. This work provides a simple strategy to tailor the morphology and structure of coal and biomass-derived porous carbon, and offers new insights into the tradeoff between SSA and mesopores for high performance supercapacitors.