Nanostructured Carbon Materials Derived from Lignin via Flame-Induced Oxidation for Supercapacitors

The development of high-performance, low-cost supercapacitors holds significant importance for the use of renewable energy. However, enhancing their energy density without compromising their inherent properties remains a formidable challenge. In this study, the method of flame-induced oxidation is introduced to enhance the wettability and porosity of lignin-based carbon nanomaterial. The results of FTIR, XRD, XPS, and Raman spectroscopy confirmed the effectiveness of flame-induced oxidation. The finally obtained carbon nanomaterial possesses a specific surface area of 497.84 m2 g–1 and abundant heteroatom content (O: 7.3%, N: 6.9%, and S: 1.5%). As a result, the assembled supercapacitors demonstrated an energy density of 26.45 W h kg–1 at a power density of 800 W kg–1. The Trasatti method and ion diffusion analysis reveal that the outstanding energy storage properties are attributed to the synergistic effect of enriched heteroatom content and developed nanopore structure. This work introduces an approach for designing carbon material with appropriate pore size and heteroatom content to develop high-performance supercapacitors.