Lignin-derived carbon aerogels with high surface area for supercapacitor applications

Abstract

Carbon materials are attracting increasing interest in the field of supercapacitors because of their well-developed porous structures, large specific surface areas, long cycle life, good conductivity, and environmental friendliness. In this study, Kraft lignin extracted from black liquor was used to synthesize a lignin precursor via the sol–gel method. Under well-controlled pyrolysis conditions, this precursor produces lignin-based carbon aerogels (LECAs) with well-developed textural structures that exhibit excellent supercapacitor performance. A LECA with a specific surface area of 3742 m2 g−1 exhibits a saturated adsorption capacity of up to 3442 mg g−1 for methylene blue. As a supercapacitor electrode material, the LECA shows an excellent specific capacitance (504.7F g−1 at 0.2 A g−1) and a high stability (87.7% capacity retention after 10,000 cycles). In addition, a symmetric LECA-based supercapacitor exhibits high energy and power densities with maximum values of 18.1 Wh kg−1 and 16000 W kg−1, respectively. This excellent energy-storage ability may be attributable to the LECA electrode, which has an ultrahigh specific surface area, suitable pore size distribution, and trace amounts of heteroatoms such as O and S. Thus, this study provides a simple, scalable approach for improving the performance of lignin-based energy-storage materials and offers a route for the high-quality utilization of lignin derived from the pulp and paper industry toward the alleviation of environmental pollution.