A combined first principles and experimental study on Al-doped Na3V2(PO4)2F3 cathode for rechargeable Na batteries

Aluminum-doped Na3V2-xAlx(PO4)2F3 cathode materials were successfully synthesized using a sol-gel method for sodium ion batteries. Rietveld refinement results for pristine Na3V2(PO4)2F3 and Na3V1.93Al0.07(PO4)2F3 confirmed that no phase change occurred after Al doping. Composition-optimized Na3V1.93...

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Bibliographic Details
Published in:Surface & coatings technology 2022-03, Vol.434, p.128184, Article 128184
Main Authors: Zhuang, Shu-Han, Yang, Chun-Chuen, Zheng, Mingtao, Rengapillai, Subadevi, Marimuthu, Sivakumar, Chiang, Yu-Shen, Chang, Bor Kae, Huang, Chia-Hung, Liu, Wei-Ren
Format: Article
Language:English
Subjects:
Aluminum
Cathode
Cathodes
Doping
Electrochemical impedance spectroscopy
Electrode materials
First principles
Mathematical analysis
Na3V2(PO4)2F3
Rechargeable batteries
Sodium
Sodium ion batteries
Sol-gel processes
Theoretical calculations
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Summary:Aluminum-doped Na3V2-xAlx(PO4)2F3 cathode materials were successfully synthesized using a sol-gel method for sodium ion batteries. Rietveld refinement results for pristine Na3V2(PO4)2F3 and Na3V1.93Al0.07(PO4)2F3 confirmed that no phase change occurred after Al doping. Composition-optimized Na3V1.93Al0.07(PO4)2F3 delivered the highest discharge capacity (121.3 mAh g−1 at 0.1C) and retained 75% capacity after 400 cycles at 5C. Rate capability testing indicates that Na3V1.93Al0.07(PO4)2F3 exhibits rates as high as 57 mAh g−1 at 10C, which was much higher (150%) than that of pristine Na3V2(PO4)2F3 (38 mAh g−1). Electrochemical impedance spectroscopy results showed that the diffusion coefficients of sodium ions could be enhanced from 3.8 × 10−14 cm2/s to 4.14 × 10−14 cm2/s after Al doping. Theoretical calculations on Na3V2(PO4)2F3 and doped material were also compared by first principle calculations in terms of bang gaps and density of states. The findings indicate that optimal Al doping makes NVPF as a promising cathode material for sodium-ion batteries. [Display omitted] •The composition-optimized Na3V1.93Al0.07(PO4)2F3 cathode deliver 121 mAh g−1 at 0.1C.•Excellent cycle stability of 75% retention after 400 cycles at 5C is demonstrated.•Impedance and rate capability are greatly enhanced by Al doping.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2022.128184