Iron trifluoride synthesized via evaporation method and its application to rechargeable lithium batteries
Iron trifluoride synthesized via evaporation method and its application to rechargeable lithium batteries
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DOI：
10.1016/j.jpowsour.2012.09.027
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发表时间：
2013-02
影响因子：
9.2
通讯作者：
Seung‐Taek Myung;Shuhei Sakurada;H. Yashiro;Yang‐Kook Sun
中科院分区：
文献类型：
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作者：
Seung‐Taek Myung;Shuhei Sakurada;H. Yashiro;Yang‐Kook Sun
介绍了通过两个连续步骤合成菱面体型FeF 3的方法：i）将Fe 2 O3酸处理，然后在80 °C下热蒸发，得到水合β-FeF 3·3 H2O; ii）在Ar气氛下，在400 °C下对所得到的β-FeF 3·3 H2O进行简单的热分解。合成后的FeF 3的X射线衍射数据的Rietveld精修表明形成了具有R3 <$c空间群的高度结晶的FeF 3结构。为了克服高离子性和提高扩散率，FeF 3在碳（乙炔黑）的辅助下进行球磨。纳米FeF 3的电化学性能在1.5-4.5 V的电压范围内不受欢迎，因为重复的嵌入-转化反应在几个循环内加速了结构破坏，尽管在Fe 3 +/0的三电子氧化还原的辅助下观察到了高容量（518 mAh（g-氟化物）-1，20 mA g-1）。将下限截止电压提高到2 V（仅允许嵌入反应），FeF 3可提供224 mAh g− 1的高容量，并显著提高容量保持率（第100次循环时为71%）。
Facile synthesis of rhombohedral type FeF3introduced via two consecutive steps is introduced: i) acidic treatment of Fe2O3followed by thermal evaporation at 80 °C resulting in hydrated β-FeF3·3H2O and ii) a simple thermal decomposition of the as-received β-FeF3·3H2O at 400 °C under an Ar atmosphere. A Rietveld refinement of x-ray diffraction data for the as-synthesized FeF3indicates the formation of a highly crystalline FeF3structure with a R3¯c space group. To overcome the high ionicity and improve the diffusivity, FeF3is ball-milled with the aid of carbon (acetylene black). The electrochemical performance of nanosized FeF3is not favored in voltage range of 1.5–4.5 V because the repetitive intercalation–conversion reaction accelerates the structural disruption within a few cycles, although a high capacity (518 mAh (g-fluoride)−1at 20 mA g−1) is observed, assisted by the three-electron redox of Fe3+/0. Raising the lower cut-off voltage to 2 V, which allows only intercalation reaction, the FeF3delivers a high capacity of 224 mAh g−1with significantly improved capacity retention (71% at 100th cycle).