Hard Carbon Anodes for Sodium-Ion Batteries: Industrial Precursors, Structural Regulation, and Future Prospects

Hard carbon is widely regarded as the most promising anode material for commercializing sodium-ion batteries. However, the successful industrial application of hard carbon requires not only the proper selection of cost-effective precursors but also precise regulation of the structures. This review aims to provide a comprehensive summary of advanced hard carbons by using commercial raw materials as precursors and the corresponding structural engineering strategies for the industrialization process. Specifically, we systematically summarize three representative and industrially feasible precursors-(resins, biomass, and needle coke)-with particular emphasis on their origins, synthesis pathways, structural optimization, and corresponding sodium-ion storage performance. In addition, we discuss the remaining challenges associated with the large-scale deployment of hard carbon and provide perspectives on future directions, including economic efficiency through low-cost precursors, environmentally friendly synthetic routes, and the implementation of recyclable manufacturing technologies. This review is expected to offer clear insights and practical guidance for the rational design and preparation of commercial hard carbon anode materials.