Zinc Single‐Atom Regulated Hard Carbons for High Rate and Low Temperature Sodium Ion Batteries

Hard carbons, as one of the most commercializable anode materials for sodium‐ion batteries (SIBs), have to deal with the trade‐off between the rate capability and specific capacity or initial Columbic efficiency (ICE), and the fast performance decline at low temperature (LT) remains poorly understood. Here, a comprehensive regulation on the interfacial/bulk electrochemistry of hard carbons through atomic Zn doping is reported, which demonstrates a record‐high reversible capacity (546 mAh g⁻¹), decent ICE (84%), remarkable rate capability (140 mAh g⁻¹ @ 50 A g⁻¹), and excellent LT capacity (443 mAh g⁻¹ @ −40 °C), outperforming the state‐of‐the‐art literature. This work reveals that the Zn doping can generally induce a local electric field to enable fast bulk Na⁺ transportation, and meanwhile catalyze the decomposition of NaPF₆ to form a robust inorganic‐rich solid‐electrolyte interphase, which elaborates the underlying origin of the boosted electrochemical performance. Importantly, distinguished from room temperature, the intrinsic Na⁺ migration/desolvation ability of the electrolyte is disclosed to be the crucial rate‐determining factors for the SIB performance at LT. This work provides a fundamental understanding on the charge‐storage kinetics at varied temperatures.