Multiscale wood-derived materials for advanced supercapacitors: from macro to micro and nano

Abstract

The investigation of sustainable and renewable energy sources, coupled with the advancement of innovative energy storage technologies, represents a vital strategy for mitigating the present-day energy crisis. Among various techniques, supercapacitors (SCs) own great potential for future energy storage given their high-power density and long cycle life. However, conventional SCs are generally constructed based on fossil-derived products, which calls for sustainable materials in functionalization. Wood-derived materials, known for their hierarchically porous structures, robust mechanical strength, and tunable multifunctionality, are considered as ideal candidates for integration into SCs. While existing literature reviews have shed light on the advanced applications of wood or cellulose-based materials in SCs, there remains a notable gap in comprehensively exploring wood-derived materials across multiple scales − from macro (bulk wood) to micro (cellulose microfibers) and nano (cellulose nanofibers and cellulose nanocrystals). This review, therefore, undertakes a thorough investigation into the design and characteristics of multiscale wood-derived materials for advanced SCs. Initially, we provide a concise overview of the energy storage mechanism, the structural composition of SCs, the key factors influencing the properties of electrode materials in SCs, and the structural properties and constituents of wood. Subsequent sections uncover the latest advancements in the fabrication of electrode materials from wood, including carbonized wood, modified wood-derived carbon, and binary and ternary composite electrode involving cellulose and its derivatives. Furthermore, we address the challenges encountered in these processes and outline prospective directions for future research in electrode and device design, thus contributing to the advancement of SC applications in the field of energy storage.