Enhanced Performance of Electrical Double-Layer Capacitor by Controlling the Specific Surface Area and Pore Structure of ZIF-67

Electrical double-layer capacitance can be enhanced by developing carbon materials with elevated specific surface area, porosity, and electrical conductivity. In this study, we demonstrate a facile approach for synthesizing carbon materials with a meticulously controlled pore structure of ZIF-67 by a precise manipulation of the precursor solution quantities. The concentration of the precursor solution affected the crystal size of ZIF-67 due to the different nucleation rates. After the carbonization of the crystals, smaller cobalt nanoparticles were formed within the carbon materials derived from the larger ZIF-67 crystal. The removal of the nanoparticles by acid treatment induced the formation of porous carbon, resulting in the enhanced performance of the electrical double-layer capacitors. The nanoporous carbon derived from the largest-sized ZIF-67 template exhibited a remarkable specific capacitance of 157 F/g at a current density of 1 A/g, retaining an impressive 85% of this value after 30,000 charging/discharging cycles at 16 A/g.