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

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.