Advancing Energy Storage Technologies Beyond Lithium With Cellulose‐Derived Sustainable Carbon Materials

The transition to sustainable, high‐performance alternatives to lithium‐ion systems is accelerating research progress in electrochemical energy storage. Cellulose‐derived carbons, made from abundant, renewable biomass, are emerging as promising candidates, offering natural environmental friendliness, adjustable structure, and functional versatility. This review examines the hierarchical architecture of cellulose, its carbonization pathways, and the influence of extraction and processing methods on precursor properties. Advances in synthetic techniques, from heteroatom doping to creating composite hybrids, are discussed for their role in controlling porosity, conductivity, and electrochemical behavior. Structure‐property relationships and function of these carbons are analyzed in the context of sodium‐, potassium‐, zinc‐, and magnesium‐ion batteries, as well as hybrid supercapacitors. Important material properties, including electrical conductivity, mechanical strength, thermal stability, and morphological control, are analyzed in relation to device performance. Challenges related to scalability, electrolyte compatibility, and cycle life are addressed, with a focus on sustainable synthesis and integration routes. This review uniquely integrates cellulose‐derived carbon across multiple postlithium energy storage systems with a focus on scalable synthesis and electrochemical optimization.