Nanosize effect on high-rate Li-ion intercalation in LiCoO2 electrode
Nanosize effect on high-rate Li-ion intercalation in LiCoO2 electrode
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DOI：
10.1021/ja0681927
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发表时间：
2007-06-13
影响因子：
15
通讯作者：
Honma, Itaru
中科院分区：
文献类型：
--
作者：
Okubo, Masashi;Hosono, Eiji;Honma, Itaru
最近，电池技术要求更高的速率能力。高倍率充放电实验的主要难点是锂离子在电极中的缓慢扩散所引起的动力学问题。纳米化是一种流行的方法，可以实现更高的表面积和更短的锂离子扩散长度，以实现快速扩散。然而，虽然已经合成了各种具有优异的高速率性能的纳米电极，但由于尺寸控制困难，尚未进行纳米晶LiCoO2的尺寸控制合成和系统研究。通过水热反应建立了尺寸控制的纳米晶LiCoO2的合成方法，并首次阐明了这种嵌入阴极材料的结构和电化学性质。通过粉末x射线衍射测量和拉曼光谱分析，发现纳米晶LiCoO2中存在晶格膨胀现象。对纳米晶LiCoO2的电化学测量和理论分析表明，在大多数应用中，小于15 nm的极端尺寸减小是不利的。在合适的粒径为17 nm的纳米晶LiCoO2中，观察到优异的高倍率性能（100℃时1c倍率性能的65%）。
Recently, battery technology has come to require a higher rate capability. The main difficulty in high-rate charge-discharge experiments is kinetic problems due to the slow diffusion of Li-ions in electrodes. Nanosizing is a popular way to achieve a higher surface area and shorter Li-ion diffusion length for fast diffusion. However, while various nanoelectrodes that provide excellent high-rate capability have been synthesized, a size-controlled synthesis and a systematic study of nanocrystalline LiCoO2 have not been carried out because of the difficulty in controlling the size. We have established the size-controlled synthesis of nanocrystalline LiCoO2 through a hydrothermal reaction and, for the first time, clarified the structural and electrochemical properties of this intercalation cathode material. Lattice expansion in nanocrystalline LiCoO2 was found from powder X-ray diffraction measurements and Raman spectroscopy. Electrochemical measurements and theoretical analyses on nanocrystalline LiCoO2 revealed that extreme size reduction below 15 nm was not favorable for most applications. An excellent high-rate capability (65% of the 1 C rate capability at 100 C) was observed in nanocrystalline LiCoO2 with an appropriate particle size of 17 nm.