Understanding the High Capacity of Li2FeSiO4: In Situ XRD/XANES Study Combined with First-Principles Calculations
Understanding the High Capacity of Li2FeSiO4: In Situ XRD/XANES Study Combined with First-Principles Calculations
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了解 Li2FeSiO4 的高容量：原位 XRD/XANES 研究与第一原理计算相结合
DOI：
10.1021/cm303685p
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发表时间：
2013-05-28
影响因子：
8.6
通讯作者：
Yang, Yong
中科院分区：
文献类型：
--
作者：
Lv, Dongping;Bai, Jingyu;Yang, Yong
用同步辐射X射线近边结构(XANES)和X射线衍射仪(X射线衍射仪)研究了正极材料Li2FeSiO4中Li+的可逆提取/插入的电化学机理。这些先进的技术为解决传统非原位方法表征的局限性提供了有效的解决方案。原位Fe Kedge XANES研究表明，Li2FeSiO4中的Fe离子在从开路电位到4.8V的充电过程中不断被氧化到高价，这有助于材料具有较高的可逆容量。用原位X射线衍射法和第一性原理理论研究揭示了Li2FeSiO4在充放电过程中的结构演化。实验和理论研究的结果是一致的，表明Li2FeSiO4在4.8V的高充电电压下发生了两个两相反应。
The electrochemical mechanism of the cathode material Li2FeSiO4 with reversible extraction/insertion of more than one Li+ from/into the structure has been studied by techniques of in situ synchrotron X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD). These advanced techniques provide effective solutions to address the limitations of characterization by traditional ex situ methods. The study of in situ Fe Kedge XANES indicates that the Fe ion in the Li2FeSiO4 is oxidized continuously to high valence during the charging process from open circuit potential to 4.8 V, which contributes to the high reversible capacities of the materials. In situ XRD and theoretical study from first-principles calculations have been employed to reveal the structural evolution of the Li2FeSiO4 underlying the high capacity during the charge/discharge process. The results of both experimental and theoretical studies are consistent and indicate that Li2FeSiO4 undergoes two two-phase reactions when the electrode is charged to a high voltage of 4.8 V.