Tailoring the Composition of a Mixed Anion Iron-Based Fluoride Compound: Evidence for Anionic Vacancy and Electrochemical Performance in Lithium Cells
Tailoring the Composition of a Mixed Anion Iron-Based Fluoride Compound: Evidence for Anionic Vacancy and Electrochemical Performance in Lithium Cells
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DOI：
10.1021/cm501396n
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发表时间：
2014-07
影响因子：
8.6
通讯作者：
M. Duttine;D. Dambournet;N. Penin;D. Carlier;L. Bourgeois;A. Wattiaux;K. Chapman;P. Chupas;H. Groult;E. Durand;A. Demourgues
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文献类型：
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作者：
M. Duttine;D. Dambournet;N. Penin;D. Carlier;L. Bourgeois;A. Wattiaux;K. Chapman;P. Chupas;H. Groult;E. Durand;A. Demourgues
微波辅助合成允许稳定具有六方钨青铜（HTB）网络的铁基氟化物化合物。化学成分的确定，即，FeF2.2（OH）0.8·（H2O）0.33，与纯氟化物组成有很大差异，OH取代氟离子的含量较高。Rietveld精修的X射线衍射数据和穆斯堡尔谱表明，部分OH/F取代对铁的结构（原子间距离、角度等）和局域环境（异构体位移和四极分裂分布）产生影响。对氟羟基化合物的热行为进行了深入研究。从室温到350 °C，在Ar气流下，HTB型结构保持稳定，没有任何氟损失，只有水离开。在T > 350 °C时，结构开始崩溃，阴离子分配导致α-FeF 3和α-Fe 2 O3。在200 °C ≤ T ≤ 350 °C范围内，化学成分可以通过不同的温度进行调节。
Microwave-assisted synthesis allows stabilizing Fe-based fluoride compounds with hexagonal tungsten bronze (HTB) network. The determination of the chemical composition, i.e., FeF2.2(OH)0.8·(H2O)0.33, revealed a significant deviation from the pure fluoride composition, with a high content of OH groups substituting fluoride ions. Rietveld refinement of the X-ray diffraction data and Mossbauer spectroscopy showed that the partial OH/F substitution impact on the structure (interatomic distances, angles, and so on) and the local environment of iron (isomer shift and quadrupole splitting distribution). The thermal behavior of the hydroxyfluoride compound has been thoroughly investigated. From room temperature to 350 °C under Ar flow, the HTB-type structure remains stable without any fluorine loss and only water departure. At T > 350 °C, the structure started to collapse with a partitioning of anions leading to α-FeF3 and α-Fe2O3. Within 200 °C ≤ T ≤ 350 °C, the chemical composition can be tuned with different c...