Lithium storage in nanostructured TiO2 made by hydrothermal growth
Lithium storage in nanostructured TiO2 made by hydrothermal growth
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DOI：
10.1021/cm035046g
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发表时间：
2004-02-10
影响因子：
8.6
通讯作者：
Graetzel, M
中科院分区：
文献类型：
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作者：
Kavan, L;Kalbác, M;Graetzel, M
以TiCl4为原料，在250℃的10M氢氧化钠中高压灭菌，然后在水和/或酸性介质中处理，制备了纳米二氧化钛材料。X-射线衍射谱和拉曼光谱证实了主相为锐钛矿的存在，但大多数材料中也含有少量的X射线衍射物相。锂的循环伏安曲线显示，除了扩散控制的锂插入锐钛矿晶格的普通峰外，还有两对可逆伪电容峰(S峰)。S峰的出现与材料的纳米片状和/或纳米管状形貌有关。这种结构是在水热条件下通过层状Na+/H+钛酸盐前驱体的剥离形成的。S峰被认为是二氧化钛纳米片量子尺寸限制的特征。含有纳米片状的材料可以用正丁基锂还原成立方LiTiO2时(在普通纳米晶锐钛矿只得到正交Li0.5TiO2时)。因此，与晶态锐钛矿相比，其电化学储锂容量更大。所制备的材料也表现出较好的插入动力学，因此它们在锂离子电池中有很好的应用前景。根据施加的电压，它们既可以作为普通的锂离子插入主机进行充放电，也可以作为超级电容器进行充放电。
Nanostructured titania materials were prepared from TiCl4 via autoclaving in 10 M NaOH at 250 degreesC and subsequent treatment in aqueous and/or acidic media. XRD and Raman spectroscopy evidenced the presence of anatase as the main phase, but most materials contained also some XRD-silent component. Cyclic voltammograms of lithium insertion demonstrate two pairs of reversible pseudocapacitive peaks (S-peaks) in addition to the ordinary peaks of diffusion-controlled Li insertion into the anatase lattice. The occurrence of S-peaks is associated with the nanosheet- and/or nanotubular morphology of the materials. This structure developed at hydrothermal conditions via exfoliation of the layered Na+/H+ titanate precursors. The S-peaks were suggested to be the signatures of quantum-size confinement in titania nanosheets. The nanosheet-containing materials are reducible by n-butyllithium to cubic LiTiO2 (at conditions when the ordinary nanocrystalline anatase gives only the orthorhombic Li0.5TiO2). Consequently, the electrochemical Li-storage capacity is larger compared to that of crystalline anatase. The prepared materials also show better insertion kinetics; hence, they are promising for applications in Li-ion batteries. Depending on the applied voltage, they can be charged/discharged either as ordinary Li-insertion hosts or as supercapacitors.