Lithium Insertion into Anatase Nanotubes
Lithium Insertion into Anatase Nanotubes
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DOI：
10.1021/cm302912f
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发表时间：
2012-11-27
影响因子：
8.6
通讯作者：
Bruce, P. G.
中科院分区：
文献类型：
--
作者：
Gentili, V.;Brutti, S.;Bruce, P. G.
采用水热法合成了锐钛矿型纳米管，并通过FE-SEM、TEM、XRD和N2吸附等手段对其进行了表征。优化的合成路线允许仔细控制最终产品的晶体结构和形态，从而得到迄今为止报道的任何纳米管的最高相和形态纯度（>90%）。在锂电池中以不同的电流速率测试了纳米碳管，并将其性能与本体和纳米颗粒纳米碳管进行了比较。锂电池中纳米管的Li吸收达到0.98/分子量单位。此外，纳米管显示出更好的可逆性和循环性相比，无论是散装和纳米颗粒的结晶。优异的速率性能与介观结构的纳米粉末报道的最佳文献值相当。结合中子衍射和拉曼显微镜的实验数据，研究了锂嵌入纳米管的机理。非原位中子衍射实验进行了原始的，部分锂化，和完全锂化的碳纳米管。同时，通过原位拉曼显微镜研究了与电化学锂插入相关的结构变化。该分析表明，与Wagemaker等人先前对小于7 nm的纳米颗粒观察到的类似，Li-贫四方晶系/正交晶系/Li-富四方晶系双相变机制。
Anatase nanotubes were synthesized by a hydrothermal route and characterized by FE-SEM, TEM, XRD, and N-2 adsorption. The optimized synthesis route permits careful control of the crystal structure and morphology of the final product, thus giving the highest phase and morphological purities (>90%) of any anatase nanotubes reported to date. The anatase nanotubes were tested in lithium cells at various current rates and their performances compared with bulk and nanoparticulate anatase. The Li uptake of the nanotubes in lithium cells reaches 0.98 per formula unit. Moreover the nanotubes show better reversibility and cyclability compared to both bulk and nanoparticulate anatase. The excellent rate performance is comparable with the best literature values reported for mesostructured anatase nanopowders. By combining experimental data from neutron diffraction and Raman microscopy the lithium insertion mechanism into the anatase nanotubes was investigated. Ex situ neutron diffraction experiments were carried out on pristine, partially lithiated, and fully lithiated anatase nanotubes. In parallel, the structural changes associated with electrochemical lithium insertion were investigated by in situ Raman microscopy. This analysis suggests a Li-poor tetragonal/orthorhombic/Li-rich tetragonal double phase transition mechanism analogous to that previously observed by Wagemaker et al. for anatase nanoparticles smaller than 7 nm.