Recent Progress in Biomass‐Based Materials for Rechargeable Batteries ^†

Comprehensive Summary Biomass‐based materials (BBMs), derived from renewable natural resources such as cellulose, hemicellulose, lignin, chitin, and proteins, have recently attracted great attention in the field of sustainable energy storage owing to their intrinsic abundance, structural diversity, and environmental compatibility. BBMs can be transformed into advanced carbon materials and other derivatives through functional design, demonstrating promising applications in various components of rechargeable batteries, including electrode materials, solid‐state electrolytes, separators, current collectors, and electrolyte additives. Their tunable pore structures, abundant functional groups, and heteroatom doping enable efficient ion transport, enhanced conductivity, and stable framework. Recent research progress has revealed that biomass derived carbon materials exhibit controllable micro‐structures and hierarchical porosity suitable for Li + , Na + , and K + storage. The introduction of BBMs into solid‐state electrolytes has improved ionic conductivity and mechanical robustness through hydrogen‐bond networks and inter‐molecular forces. Meanwhile, cellulose and chitosan‐ based separators provide excellent wettability, mechanical strength, and dendrite suppression ability, which promote the development of long‐ term batteries. However, the poor batch‐to‐batch repeatability, unsatisfactory oxidation stability at high voltages of BBMs still restrained their practical applications in secondary batteries. This review systematically summarizes the molecular structure and functional groups of different types of biomasses. Then, the influence of nano/micro structures on determining specific utilization of BBMs in different battery systems is mainly discussed. Following this, the key scientific challenges of modulating the structures of BBMs and the gap in their functional realization for high‐performance batteries are emphatically discussed. Finally, we provide an outlook on potential structural design strategies and chemical treatment approaches for biomass materials to enhance their electrochemical performance in various roles, which will accelerate the development of these green resources and their practical applications in energy storage. Key Scientists