LiF/Fe nanocomposite as a lithium-rich and high capacity conversion cathode material for Li-ion batteries
LiF/Fe nanocomposite as a lithium-rich and high capacity conversion cathode material for Li-ion batteries
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DOI：
10.1016/j.jpowsour.2012.05.111
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发表时间：
2012-11
影响因子：
9.2
通讯作者：
Ting Li;Zhong X. Chen;X. Ai;Y. L. Cao;Hanxi Yang
中科院分区：
文献类型：
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作者：
Ting Li;Zhong X. Chen;X. Ai;Y. L. Cao;Hanxi Yang
以刚性纳米TiN为研磨粉，采用机械球磨法制备了富锂LiF/Fe纳米复合材料，以满足当前锂离子电池技术的需要。结构表征表明，该纳米复合材料是由高能球磨生成的LiF和Fe粒子分散紧密接触形成的，为LiF和Fe的可逆转化反应形成了合适的电极活性纳米结构域。电化学测试表明，含有50wt%LiF和Fe活性物质的LiF/Fe纳米复合材料在20mAg−1时的可逆容量为568mAhg−1(仅以LiF和Fe的重量计算)，接近复合材料的理论容量(600mAhg−1)，而且在室温下也表现出很强的功率容量，即使在500mAg∼1的很高的倍率下也可以达到−300mAhg−1。循环伏安和X射线衍射分析证实，LiF/Fe纳米复合材料几乎可以通过LiF/Fe电化学转化为FeF3实现三电子转移，反之亦然。这些结果表明，通过电化学转化，可以将廉价的氟化锂和金属组成的富锂复合材料用作下一代锂离子电池的大容量正极材料。
Lithium-rich LiF/Fe nanocomposite is prepared by a simple route of mechanical ball-milling of lithium fluoride and iron using rigid TiN nanoparticles as the grinding powders, and studied as a lithium-rich cathode material for satisfying the present Li-ion battery technology. The structural characterizations reveal that the nanocomposite is composed of well-dispersed and intimately contacted LiF and Fe particles created by high-energy ball-milling, forming appropriate electrode-active nanodomains for the reversible conversion reaction of LiF and Fe. Electrochemical measurements demonstrate that the LiF/Fe nanocomposite containing 50wt% active materials of LiF and Fe can deliver a high reversible capacity of 568mAhg−1at 20mAg−1(calculated using the weight of LiF and Fe only), approaching the theoretical capacity of the composite (600mAhg−1), and also show a strong power capability with a reversible capacity of ∼300mAhg−1even at a very high rate of 500mAg−1at room temperature. CV and XRD analyses confirm that the LiF/Fe nanocomposite can nearly realize a three-electron transfer through electrochemical conversion of LiF/Fe to FeF3and vice versa. These results suggest the possibility to utilize the inexpensive lithium-rich composites of lithium fluoride and metals as high-capacity cathode materials for future-generation Li-ion batteries through the electrochemical conversion.