P-Band Center Engineering of Sulfur to Weaken Fe─S Bond Toward Superior Sodium-Ion Storage.
basic_science · Level V
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- Record sourced from PubMed, PMID 40391639.
- Also identified by DOI 10.1002/adma.202506071.
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Abstract
Iron-based sulfides are appealing anodes of sodium-ion batteries (SIBs) due to the high theoretical capacity, low-cost, and excellent mechanical/thermal stability. However, achieving high electrochemical performances in such anodes is hindered by the strong Fe─S bonds and sluggish kinetics. Here, a unique carbon-coated iron sulfide composite with abundant S vacancies (v-FeS<sub>2</sub>@C) is designed, the spin polarization and S vacancy lift the p-band center (ɛ <sub>p</sub>) of S and then decouple it from the d-band center (ɛ<sub>d</sub>) of Fe, which weakens Fe─S bond and strengthens Na─S interaction. The obtained v-FeS<sub>2</sub>@C anode exhibits ultrahigh rate capability of 438.0 mAh g<sup>-1</sup> at 70 A g<sup>-1</sup> and remarkable long-life cycle performance (512.5 mAh g<sup>-1</sup> after 8000 cycles at 40 A g<sup>-1</sup>). Particularly, the sodium-ion full cell composed of v-FeS<sub>2</sub>@C anode and Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> cathode delivers the best specific capacity (211.5 mAh g<sup>-1</sup> at 40 A g<sup>-1</sup>) and long cyclic stability (459.5 mAh g<sup>-1</sup> after 2000 cycles at 5 A g<sup>-1</sup>). Such performances are much more superior to those of the other iron-based sulfides. This work provides a new paradigm for boosting SIBs' performances of iron-based sulfides by regulating p-band center (ɛ<sub>p</sub>) of S and weakening Fe─S bonds.