Recent Advances in Presodiation Strategies for Hard Carbon in Sodium-Ion Batteries: Mechanisms of SEI Regulation and Electrochemical Performance.

Sodium-ion batteries (SIBs) have emerged as promising candidates for large-scale energy storage, while the practical application of hard carbon (HC) anodes is hindered by their low initial coulombic efficiency (ICE) caused by irreversible Na consumption during solid electrolyte interphase (SEI) formation. Presodiation compensates for irreversible Na loss, yet its effects on interphase formation and evolution remain poorly resolved across processing routes. In this review, we summarize physical, chemical, electrochemical, and sacrificial-additive strategies through the lens of SEI formation and evolution, relating the timing, composition, morphology, and spatial distribution of the interphase to its reconstruction during post-treatment, electrolyte exposure, and cycling. We further connect these interfacial features with ICE, interfacial resistance, rate capability, energy density, and cycling stability, thereby identifying how presodiation conditions govern SEI development in HC anodes. Finally, the remaining challenges and future opportunities for SEI-oriented presodiation design are discussed to accelerate the practical development of better SIBs.