Insights into Gas-Exfoliation and the In-Situ Template Mechanism of Zinc Compound for Lignin-Derived Supercapacitive Porous Carbon

The large-scale production of porous activated carbon is plagued by the overuse of corrosive activators, so developing a green and mild activation strategy is technologically urgent and meaningful. Herein, two gentle activators (ZnCO 3 and ZnC 2 O 4 ) and a traditional corrosive agent (ZnCl 2 ) are utilized to activate lignin for porous carbons, and the microstructures and electrochemical properties of the carbons are systematically investigated. By tracking the evolution of the carbonized products through TG-MS, in-situ FT-IR, and other characterization methods, the gas-exfoliation and in-situ template functions of ZnCO 3 and ZnC 2 O 4 are proposed. It was found that the pyrolysis synergistic effect between ZnC 2 O 4 and lignin boosts the decomposition of oxygen-containing groups, playing a pivotal role in the fabrication of hierarchical porous carbon with crumpled nanosheets. The electrochemical properties of the carbons are closely correlated to their porous structures. Benefiting from the well-developed crumpled lamellar units, the hierarchical porous carbon activated by ZnC 2 O 4 has a high specific surface area and good conductivity. Consequently, it exhibits a higher capacitance than the microporous carbon activated by ZnCl 2 and the mesoporous carbon activated by ZnCO 3 .