Constructing the Interconnected and Hierarchical Nanoarchitectonics in Coal-Derived Carbon for High-Performance...

Because of the deep and zigzag microporous structure, porous carbon materials exhibit inferior capacitive performance and sluggish electrochemical kinetics for supercapacitor electrode materials. Herein, a single-step carbonation and activation approach was utilized to synthesize coal-based porous carbon with an adjustable pore structure, using CaO as a hard template, KOH as an activator, and oxidized coal as precursors to carbon. The obtained sample possesses an interconnected and hierarchical porous structure, higher SSA (1060 m² g^-1), suitable mesopore volume (0.25 cm³ g^-1), and abundant surface heteroatomic functional groups. Consequently, the synthesized carbon exhibits an exceptionally high specific capacitance of 323 F g^-1 at 1 A g^-1, along with 80.3% capacitance retention at 50 A g^-1. The assembled two-electrode configuration demonstrates a remarkable capacitance retention of up to 95% and achieves Coulombic efficiency of nearly 100% with 10,000 cycles in a 6 M KOH electrolyte. Furthermore, the Zn-ion hybrid capacitor also exhibits a specific capacity of up to 139.1 mA h g^-1 under conditions of 0.2 A g^-1. This work offers a simple method in preparation of coal-based porous carbon with controllable pore structure.