The phase transition behaviors of Li1−xMn0.5Fe0.5PO4 during lithium extraction studied by in situ X-ray absorption and diffraction techniques
The phase transition behaviors of Li1−xMn0.5Fe0.5PO4 during lithium extraction studied by in situ X-ray absorption and diffraction techniques
复制标题
DOI：
10.1016/j.elecom.2009.08.044
复制
发表时间：
2009-10
影响因子：
5.4
通讯作者：
K. Nam;W. Yoon;K. Zaghib;K. Chung;Xiao‐Qing Yang
中科院分区：
文献类型：
--
作者：
K. Nam;W. Yoon;K. Zaghib;K. Chung;Xiao‐Qing Yang
LiMnyFe 1 − yPO 4型正极材料在锂提取/嵌入过程中如何发生结构变化是一个重要的问题，特别是如果它们经历单相反应（即，固溶体反应）或两相反应区。本文采用X射线吸收光谱（XAS）和X射线衍射（XRD）技术研究了碳包覆Li 1 − xMn0.5Fe0.5PO4（CLi 1 −xMn0.5Fe0.5PO4，0.0 μ x 1.0）样品在首次充电过程中的相变行为。结合XAS和XRD的结果，在3.6V（Fe 2 +/Fe 3+）和4.2V（Mn 2 +/Mn 3+）的两个电压平台处清楚地确定了两个两相共存区域，以及在两个两相区域之间通过单相反应进行的窄的中间区域。此外，首次报道并讨论了在窄单相区Fe ~（2+）/Fe ~（3+）和Mn ~（2+）/Mn ~（3+）的同时氧化还原反应。
How the structural changes take place in LiMnyFe1−yPO4-type cathode materials during lithium extraction/insertion is an important issue, especially on if they go through the single-phase reaction (i.e., solid solution reaction) or the two-phase reaction regions. Here we report the studies on the phase transition behaviors of a carbon coated Li1−xMn0.5Fe0.5PO4(CLi1−xMn0.5Fe0.5PO4, 0.0⩽x⩽1.0) sample during the first charge using in situ X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques. The combination of in situ XAS and XRD results clearly identify two two-phase coexistence regions at two voltage plateaus of 3.6 (Fe2+/Fe3+) and 4.2V (Mn2+/Mn3+) and a narrow intermediate region which proceeds via single-phase reaction in between two two-phase regions. In addition, simultaneous redox reactions of Fe2+/Fe3+and Mn2+/Mn3+in the narrow single-phase region are reported and discussed for the first time.