Mechanically alloyed Sn-Fe(-C) powders as anode materials for Li-ion batteries -: I.: The Sn2Fe-C system
Mechanically alloyed Sn-Fe(-C) powders as anode materials for Li-ion batteries -: I.: The Sn2Fe-C system
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DOI：
10.1149/1.1391622
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发表时间：
1999-02-01
影响因子：
3.9
通讯作者：
Dahn, JR
中科院分区：
文献类型：
--
作者：
Mao, O;Dunlap, RA;Dahn, JR
我们已经通过机械合金化方法或通过直接熔化元素粉末制备了Sn-Fe-C吉布斯三角形中的金属间化合物相和这些相的混合物。这是三部分系列中的第一篇文章，重点关注落在收集Sn 2Fe和C的两相线上的材料。使用原位X射线衍射，穆斯堡尔谱和电化学方法，我们表明，在Li/Sn 2Fe电池中，Sn 2Fe与Li反应形成锂锡合金和非常小的金属铁颗粒。该反应的实验容量为约800 mAh/g，如预期的那样。在这种电池的第一次充电期间，可以提取约650 mAh/g的Li，直到相对于Li为1.5V。这些材料的密度接近7 g/cm（3），因此已经获得了接近4500 Ah/L的首次循环容量。我们希望所形成的铁将充当导电的非活性基质以支撑Li-Sn合金晶粒，并且将产生良好的循环行为。然而，这些材料在1.5和0.0V之间的延长的循环寿命是差的。另一方面，如果将循环范围限制在0.0和0.55V之间，则获得合理的循环寿命，但是在这种情况下，不可逆容量为约600 mAh/g，可逆容量仅为约200 mAh/g。我们将在本系列的下一篇文章中展示克服这些困难的策略。(C)1999年电化学学会。S0013-4651（98）04-052-X。All rights reserved.
We have prepared intermetallic phases and mixtures of such phases in the Sn-Fe-C Gibbs' triangle by mechanical alloying methods or by direct melting of elemental powders. This first paper in a three-part series focuses on the materials which fall on the two-phase line collecting Sn2Fe and C. Using in situ X-ray diffraction, Mossbauer spectroscopy, and electrochemical methods, we show that Sn2Fe reacts with Li in Li/Sn2Fe cells to form lithium-tin alloys and very small metallic iron grains. The experimental capacity for this reaction is about 800 mAh/g, as expected. During the first charge of such cells about 650 mAh/g of Li can be extracted up to 1.5 V vs. Li. The density of these materials is near 7 g/cm(3), so first-cycle volumetric capacities near 4500 Ah/L have been attained. It was our hope that the formed iron would act as an electrically conductive, inactive matrix to support the Li-Sn alloy grains and that good cycling behavior would result. However, the extended cycling life of these materials between 1.5 and 0.0 V is poor. On the other hand, reasonable cycle life is obtained if the cycling range is restricted to between 0.0 and 0.55 V, but in this case, the irreversible capacity is about 600 mAh/g and the reversible capacity only about 200 mAh/g. We show strategies to overcome these difficulties in the next papers in this series. (C) 1999 The Electrochemical Society. S0013-4651(98)04-052-X. All rights reserved.