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High-voltage Na3V2(PO4)2F3 cathodes enabled by low-valence metal cations
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DOI：10.1126/sciadv.aed1452.png)
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Abstract
En 中文
Na3V2(PO4)2F3 (NVPF) is regarded as a highly promising cathode material for sodium-ion batteries. Here, we propose a general strategy for modulating the local electronic structure of vanadium (V) by introducing low-valence metal ions, such as Cu2+, Cd2+, and Ag+. This approach microscopically shortens the length of the suspended V─F2 bonds within the NVPF framework, effectively mitigating the loss of fluorine and the formation of undesirable Na3V2(PO4)3 (NVP). Consequently, this intervention indirectly enhances the overall working voltage and energy density of the battery. Density functional theory (DFT) is used to verify and deeply investigate the intrinsic mechanism of fluorine stabilization in the NVPF system. The experimental results show that NVPF with 2.5% of doped Cu exhibits a higher mid-working voltage (3.69 volts), higher energy density (447.7 watt-hours per kilogram), and excellent cycling stability (83.3% capacity retention at 20 C after 10,000 cycles).
Keywords:
Na3V2(PO4)2F3
sodium-ion batteries
low-valence metal doping
fluorine stabilization
density functional theory
Journal
IF:
12.5
Papers:
2.0W
Citations:
18.1W