Recent Progress in Hard Carbon Anodes for Sodium‐Ion Batteries

With the rapid development of renewable energy and the growth of energy demand, sodium‐ion batteries (SIBs) have attracted much attention from researchers as a promising energy storage technology. Hard carbon anodes are considered to be the most promising anodes of SIBs because of their low sodium storage potential, high capacity, wide range of raw materials, and environmental friendliness. However, the rate capability and initial coulombic efficiency of hard carbon hinder the further commercialization of hard carbon. This review provides a concise overview of the three microstructures and four sodium storage mechanisms of hard carbon and comprehensively introduces the latest research progress on strategies to effectively improve the electrochemical performance of hard carbon anodes, which are categorized into structural and morphology design, precursors selection, electrolyte optimization, surface engineering, and pre‐sodiation as modification strategies. In addition, the current research progress on sodium‐ion full batteries is also encapsulated and the developmental prospects of hard carbon anodes in SIBs is looked forward to.