The Past, Present, and Future of Biomass‐Derived Hard Carbon for Sodium‐Ion Batteries

Given the cost-effectiveness, renewability, and environmental friendliness features, biomass-derived hard carbon has attracted significant attention in sodium-ion batteries (SIBs). However, the macroproperties of the resultant hard carbon highly depend on the resources and components of the biomass precursors. And the structure-property relationship remains complicated, which brings huge challenges for subsequent research. To clarify such intrinsic correlation, this review systematically elucidates the physicochemical propert ies, multiscale mechanisms, as well as isolation approaches of the cellulose, hemicellulose, and lignin first, with special focus on the differential evolution behavior and its synergistic transformation mechanism of these three main components during the pyrolysis-carbonization process. Then, the key regulation effects on microstructure and sodium storage performance have also been illuminate d based on the structural evolution of these component s. Subsequently, by comparing different modification methods, an innovative precursor pretreatment strategy for component matching and correlation with sodium storage characteristics has been proposed, which can control the path of degradation and reconstruction of components and thus optimize the electrochemical behaviors of the resulting hard carbons. Finally, multi-dimensional solutions are raised in order to target the industrialization bottlenecks. These solutions provide a theoretical foundation and technical roadmap for the development of high-performance, low-cost SIBs anode materials.