α-Fe2O3 nanoflakes as an anode material for Li-ion batteries
α-Fe2O3 nanoflakes as an anode material for Li-ion batteries
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DOI：
10.1002/adfm.200601186
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发表时间：
2007-10-15
影响因子：
19
通讯作者：
Chowdari, B. V. R.
中科院分区：
文献类型：
--
作者：
Reddy, M. V.;Yu, Ting;Chowdari, B. V. R.
采用热处理方法在铜箔上制备了α - Fe₂O₃纳米片。通过X射线衍射、扫描电子显微镜、高分辨率透射电子显微镜和拉曼光谱对纳米片进行了表征。在环境温度下，以锂金属作为对电极和参比电极，通过循环伏安法、恒电流充放电循环和阻抗谱测量，对α - Fe₂O₃纳米片的可逆锂循环性能进行了评估。结果表明，在65 mA g⁻¹（0.1C倍率）下，在0.005 - 3.0 V的电压范围内循环时，Fe₂O₃纳米片表现出（680 ± 20）mA h g⁻¹的稳定容量，相当于每摩尔Fe₂O₃对应（4.05 ± 0.05）摩尔的锂，在80次循环内没有明显的容量衰减，并且在循环过程中（第15次循环之后）库仑效率> 98%。平均放电电压和充电电压分别为1.2 V和2.1 V。根据涉及纳米相Fe - 0 - Li₂O的“转换反应”，对观察到的循环伏安图和阻抗谱进行了分析和解释。通过与文献中报道的Fe₂O₃纳米颗粒和纳米管的结果进行比较，明确了Fe₂O₃纳米片的优越性能。
Nanoflakes of alpha-Fe2O3 were prepared on Cu foil by using a thermal treatment method. The nanoflakes were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. The reversible Li-cycling properties of the alpha-Fe2O3 nanoflakes have been evaluated by cyclic voltammery, galvanostatic discharge-charge cycling, and impedance spectral measurements on cells with Li metal as the counter and reference electrodes., at ambient temperature. Results show that Fe2O3 nanoflakes exhibit a stable capacity of (680 +/- 20) mA h g(-1), corresponding to (4.05 +/- 0.05) moles of Li per mole of Fe2O3 with no noticeable capacity fading up to 80 cycles when cycled in the voltage range 0.005-3.0 V at 65 mA g(-1) (0.1 C rate), and with a coulombic efficiency of > 98 % during cycling (after the 15th cycle). The average discharge and charge voltages are 1.2 and 2.1 V, respectively. The observed cyclic voltammograms and impedance spectra have been analyzed and interpreted in terms of the 'conversion reaction' involving nanophase Fe-0-Li2O. The superior performance of Fe2O3 nanoflakes is clearly established by a comparison of the results with those for Fe2O3 nanoparticles and nanotubes reported in the literature.