<p>Biomass-derived carbons show promise as sustainable anode materials for lithium-ion batteries, but there is a lack of understanding of how different biomass molecular and chemical structures influence graphitization processes and electrochemical behavior. Here, we investigate the structural properties and lithium storage behavior of carbons produced via iron-catalyzed pyrolysis of three different biomass precursors (lignin, cellulose, and dextrin). Spectroscopic signatures reveal differences in functional group chemistry and iron binding between the glucose-based polymers and lignin. Iron-catalyzed graphitization was effective for cellulose and dextrin precursors at temperatures as low as 1000°C, whereas lignin exhibited minimal graphitization. Following pyrolysis at 1400°C, cellulose produced the highest degree of graphitic ordering and delivered an average reversible lithium storage capacity of 278 mAh g⁻¹, while lignin showed the lowest (155 mAh g⁻¹). Pre-oxidation of the lignin prior to pyrolysis revealed a strong correlation between enriched carbonyl functionalities and the extent of graphitization, and it enabled improvement of the reversible capacity to 216 mAh g⁻¹. Overall, this work demonstrates that precursor molecular architecture and functional group chemistry dictate graphitization pathways, and it provides design guidelines for engineering biomass-derived precursors for high-performance anode materials.</p> Graphical abstract <p></p>