Lignin as a renewable carbon platform for electrochemical energy storage: structural insights, conversion pathways, and performance perspectives

Abstract

The rapid growth in global energy demand has increased the need for sustainable energy storage technologies. Electrochemical devices such as batteries and supercapacitors play an important role in modern energy storage systems. However, electrode materials, the main component of these devices, are often associated with high costs, limited supply, and geopolitical risks. In this context, lignin, an abundant and renewable plant-derived biopolymer, has attracted growing interest as a potential electrode material owing to its high carbon content, aromatic structure, and diverse functional groups. This review summarizes recent advances in the use of lignin as a carbon precursor and functional additive for electrochemical energy storage. It covers lignin chemistry, biomass-dependent structural diversity, isolation technologies, chemical modification strategies, and their applications in supercapacitors, lithium-ion batteries, and sodium-ion batteries. Beyond providing a descriptive overview, the review critically examines lignin-derived energy-storage materials through a continuous structure-process-property-performance framework. Particular attention is given to how biomass origin and lignin isolation chemistry determine molecular characteristics, including monomer composition, interunit linkage distribution, molecular condensation, and functional-group chemistry. These precursor characteristics are subsequently linked to carbonization and activation behavior, pore development, graphitic ordering, heteroatom retention, and surface chemistry. The resulting physicochemical properties are then correlated with ion transport, electrical conductivity, charge-storage mechanisms, electrochemical performance, and device-level relevance in supercapacitors, lithium-ion batteries, and sodium-ion batteries. By integrating these interconnected stages, this review provides mechanistic design principles for the rational development of sustainable lignin-derived electrode materials for next-generation energy storage technologies.