Recent Progress in Biomass-Derived Electrode Materials for High Volumetric Performance Supercapacitors

Tremendous efforts have been spent on the development of electrical energy storage (EES) systems with high volumetric performance in the past few years due to the evergrowing demand of miniaturized, portable electronic devices, and electric vehicles. Among all the EES devices, supercapacitors with electrode materials derived from biosources have attracted special attention due to their eco-friendliness, natural abundance, their intrinsic porous structures as well as their renewable and sustainable features. However, the relatively low packing densities make their specific volumetric capacitance intrinsically low, which has largely limited their further application in the supercapacitors. To address these issues, various promising approaches ranging from structural manufacture to compositional design are applied and significant breakthroughs are witnessed in recent years. In this progress report, key factors influencing the volumetric performance of biomass-derived electrode materials are systematically discussed with a particular focus spanning from fundamental to operational aspects. This work provides insights into the development of high-volumetric-performance biomass-derived supercapacitors by comprehensively summarizing recent advances in the rational structural design and fabrication. Perspectives regarding the future challenges and promising research directions on the design of next-generation EES devices are also provided.