Electrochemical and Structural Investigation of the Mechanism of Irreversibility in Li3V2(PO4)3 Cathodes

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• 作者：Soojeong Kim ; Zhengxi Zhang ; Senlin Wang ; Li Yang ; Elton J. Cairns ; James E. Penner-Hahn ; Aniruddha Deb
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：April 7, 2016
• 年：2016
• 卷：120
• 期：13
• 页码：7005-7012
• 全文大小：454K
• ISSN：1932-7455

文摘

Lithium-ion batteries dominate the battery field, particularly for electric and hybrid vehicles. Monoclinic Li₃V₂(PO₄)₃ has emerged as one of the most promising candidates for the cathode in lithium-ion batteries, offering better environmental safety and lower cost than competing materials. We have used in situ X-ray absorption spectroscopy to characterize the evolution of the vanadium in a Li₃V₂(PO₄)₃ cathode as it is cycled electrochemically. These data demonstrate the presence of significant kinetic effects such that the measured electrochemical behavior does not represent the bulk vanadium. When the cell is cycled between 3 and 4.5 V, there are two distinct vanadium species. When the potential is raised above 4.5 V, a third species is observed, consistent with formation of V⁵⁺. XANES data for the cathode after 3–4.8 V cycling are consistent with a severely distorted vanadium site, suggesting that lithium–vanadium antisite mixing may be responsible for the electrochemical irreversibility that is seen above 4.5 V.