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

Hard carbons (HCs) 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, we report a comprehensive regulation on the interfacial/bulk electrochemistry of hard carbons through atomic Zn doping, 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 low-temperature (LT) capacity (443 mAh g -1 @ -40°C), outperforming the state-of-the-art literature. We unveil that the Zn doping can generally induce a local electric field to enable the fast bulk Na + transportation, and meanwhile catalyze the decomposition of NaPF 6 to form a robust inorganic-rich solid-electrolyte interphase (SEI), 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. This article is protected by copyright. All rights reserved.