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Revisiting of Tetragonal NaVPO4F: A High Energy Density Cathode for Sodium-Ion Batteries

Authors
  • Ling, Moxiang
  • Lv, Zhiqiang
  • Li, Fan
  • Zhao, Junmei
  • Zhang, Huamin
  • Hou, Guangjin
  • Zheng, Qiong
  • Li, Xianfeng
Publication Date
Jul 08, 2020
Source
Institutional Repository of Institute of Process Engineering, CAS (IPE-IR)
Keywords
License
Unknown
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Abstract

Tetragonal NaVPO4F has been regarded as an ideal cathode for sodium-ion batteries because of its high average plateau (3.8 V) and theoretical specific capacity (143 mA h g(-1)). However, the Na-storage performance is still hindered by unsatisfying thermal stability and poor conductivity. Herein, a stable tetragonal NaVPO4F has been synthesized by a novel solvent thermal method using a carbon coating precursor. The as-prepared [email protected] nanocomposite delivers a capacity of 133 mA h g(-1) at 0.2 C, corresponding to an excellent energy density of 509 W h kg(-1) ; when coupled with an HC anode, the full cell still displays an outstanding performance of 124 mA h g(-1) at 0.05 C. Fast Na+ diffusion kinetics (DNa+ = 10(-12) to 10(-10) cm(2) s(-1)) and small volume change (4.4%) are exploited, which ensures good rate trait and cycling stability of tetragonal NaVPO4F. Further, the Na+ extraction-insertion mechanism has been explored by analyzing the crystal structure change during in situ X-ray powder diffraction cycles.

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