ZnCl 2 -KOH modulation of biomass-derived porous carbon for supercapacitors

With the implementation of carbon neutrality, more and more researchers are devoted to the development of biomass-based porous carbon materials using agricultural and forestry wastes for energy storage applications. However, biomass-derived carbon materials are still suffering from structural instability and difficult to regulate the pore structure, so it is very essential to study the regulation of pore structure in activation process of biochar. Therefore, this work developed an approach to modulate the pore structure of biomass porous carbon. The pyrolyzed biochar was primary activated by ZnCl₂ to form the intermediate FC, and the FC was secondary activated by the impregnation method with the addition of trace KOH to form the graded porous carbon FCK-x. The prepared porous carbon exhibited a large specific surface area (2845 m²g⁻¹) and a large pore volume (1.43 cm³g⁻¹), which is very favorable for efficient ion transport in the three-electrode system, FCK-0.6 exhibited a specific capacitance of 321.7 F/g at 1A/g and the assembled supercapacitor exhibited high capacitance retention (95.17%) and charge retention (85%). This work provides a feasible way to modulate biomass pore structure.