Lignin and its carbon derivatives: Synthesis techniques and their energy storage applications

Lignin, a complex phenolic polymer abundantly present in the papermaking and biofuel industries, stands out as a cost-effective, plentiful, and non-toxic material. In recent years, there has been significant interest in utilizing this green biopolymer for energy storage devices. This review thoroughly examines lignin structure, chemistry, and classification based on separation techniques. It then explores the most recent breakthroughs in creating carbon materials (nanosheets, nanofibers, spheres, composites, and 3D hierarchical porous carbon) from lignin, discussing its versatility in supercapacitors and batteries. Finally, this study highlights future materials and their prospects, the critical challenges which must be addressed while suggesting future research avenues for lignin-derived carbon materials in energy storage. By combining insights from different studies, this review aims to offer readers a thorough understanding of how lignin-derived carbon materials could play a crucial role in promoting sustainable energy solutions.