Recent advances in presodiation strategies for hard carbon anodes in sodium-ion batteries

Hard carbon (HC) has emerged as a promising anode material for sodium-ion batteries (SIBs) owing to its low cost, abundant renewable resources, and high specific capacity. However, its practical application is significantly hindered by the severe initial irreversible capacity loss resulting from sodium consumption during the first cycle. To address this issue, a variety of presodiation strategies have been developed to compensate for the sodium loss and improve the initial coulombic efficiency. In this review, recent advances in presodiation techniques for HC anodes are systematically summarized, including physical, short-circuit, electrochemical, and chemical presodiation approaches. The advantages and limitations of each method are also analyzed from the perspectives of safety, operability, and presodiation efficiency. Finally, the current challenges are outlined and future development directions are proposed to guide the development of efficient and scalable presodiation strategies for hard carbon anodes in practical Na-ion batteries.