ABSTRACT High‐performance cathode materials are essential for the commercialization of sodium‐ion batteries (SIBs) in large‐scale energy storage. However, the NASICON‐type Na 3.12 Fe 2.44 (P 2 O 7 ) 2 cathode with promising structural stability and electrochemical properties has been plagued by sluggish electronic and ionic kinetics. To address this, we develop a series of superior rate and ultra‐stable Na 3.12‐2x Fe 2.44+x (P 2 O 7 ) 2 (NFPO) cathodes through a deliberate bulk defect‐engineering strategy that enables precise control of iron vacancies (V Fe ) and oxygen vacancies (V O ). Structural characterizations confirm that the material retains phase‐pure triclinic P ‐1 framework and the introduction of V Fe –V O divacancies, which induce an upshift of the valence band. Remarkably, density functional theory (DFT) calculations elucidate a dual‐functional mechanism, as V Fe and V O not only narrow the band gap but also drastically reduce the Na + migration barrier by 1.317 eV. Benefiting from this dual kinetic enhancement, the optimized NFPO@C (x = −0.1) cathode exhibits superior rate capability with a reversible capacity of 129.6 mAh g −1 at 1C, and exceptional cycling stability, retaining 99.6% of its capacity (100.8 mAh g − 1 ) after 12 000 cycles at 20C. This study establishes rational Fe and O divacancy engineering as an effective strategy to synergistically boost electronic/ionic transport, offering a generalizable paradigm for advanced polyanionic compounds in next‐generation energy storage.
Xie et al. (Wed,) studied this question.
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