From biomass to batteries: Cutting-edge advances in hard carbon anodes for sustainable sodium-ion energy storage

Sodium-ion batteries (SIBs) have emerged as a highly promising large-scale energy storage technology following lithium-ion batteries (LIBs), due to their remarkable cost-effectiveness and safety advantages. The development of electrode materials that combine excellent electrochemical performance with low-cost benefits is crucial for driving the commercialization of this technology. Among anode materials, biomass-derived hard carbon has attracted significant attention for its low cost, abundance, and simple preparation process. However, the structural design and scalable, controllable synthesis of high-performance hard carbon still encounter systematic technical challenges. This review comprehensively sums up the significant progress made by researchers in hard carbon microstructure, sodium storage mechanisms, and modification strategies. Moreover, it delves into the intrinsic connections between the structure, performance, and processing of hard carbon materials. Additionally, the challenges in the mass production of hard carbon and future research directions are underscored. This review aims to offer valuable insights for the research, development, and industrialization of high-quality hard carbon anodes