Research Progress on Pre‐Sodiation Strategies for Non‐Aqueous and Aqueous Sodium‐Ion Batteries

ABSTRACT Sodium ion batteries (SIBs) are emerging as promising candidates for large‐scale energy storage owing to the natural abundance and low cost of sodium resources. However, irreversible capacity loss during initial solid electrolyte interphase formation and subsequent cycling remains a major challenge, fundamentally limiting energy density and cycle life. Pre‐sodiation strategies have been developed to compensate for irreversible sodium loss, thereby remarkably improving reversible capacity and cycling stability. In this review, we systematically summarize recent advances in pre‐sodiation approaches for both non‐aqueous and aqueous SIBs, categorized into anode‐based, cathode‐based, and electrolyte‐based strategies. The underlying mechanisms are examined, and remaining challenges and future research directions toward the rational design of high‐performance SIBs are discussed.