Effect of LiCoO2 Cathode Nanoparticle Size on High Rate Performance for Li-Ion Batteries
Effect of LiCoO2 Cathode Nanoparticle Size on High Rate Performance for Li-Ion Batteries
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DOI：
10.1149/1.3111031
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发表时间：
2009-01-01
影响因子：
3.9
通讯作者：
Cho, Jaephil
中科院分区：
文献类型：
--
作者：
Jo, Minki;Hong, Young-Sik;Cho, Jaephil
使用在200 ℃下获得的具有50 nm粒度的水热制备的油胺封端的LiCoO 2纳米颗粒，研究了LiCoO 2阴极纳米颗粒尺寸对Li离子电池中的高倍率性能的影响。在500、700和900 ℃下退火后，所制备的LiCoO 2的粒径分别增加到100 nm、300 nm和1 μ m。非原位透射电子显微镜和X射线衍射结果表明，固体电解质界面（SEI）的厚度影响粒子的电化学性能在高速率。具有较小粒度的LiCoO 2阴极具有较厚的SEI层，其充当Li离子扩散的屏障，导致在较高C倍率下的倍率性能劣化。然而，无论颗粒尺寸如何，循环后没有结构降解。在两种不同的电极密度（3.4和2.8 g/cm（3））下进行倍率性能测试，并且具有300 nm粒度的LiCoO 2在较高的C倍率下表现出最佳的倍率性能。在7 C倍率下长时间循环时，粒径为300 nm的LiCoO 2在3.4和2.8 g/cm（3）下分别表现出87和150 mAh/g的电流密度。
The effect of LiCoO2 cathode nanoparticle size on high-rate performance in Li-ion batteries was investigated using hydrothermally prepared oleylamine-capped LiCoO2 nanoparticles with a particle size of 50 nm obtained at 200 degrees C. Upon annealing as-prepared LiCoO2 at 500, 700, and 900 degrees C, the particle size increased to 100 nm, 300 nm, and 1 mu m, respectively. Ex situ transmission electron microscopy and X-ray diffraction results indicated that the thickness of the solid electrolyte interface (SEI) affected the particle's electrochemical properties at high rates. A LiCoO2 cathode with a smaller particle size had a thicker SEI layer, which acted as a barrier for Li-ion diffusion, resulting in deteriorated rate capabilities at higher C rates. However, irrespective of the particle size, there was no structural degradation after cycling. Rate capability tests were performed under two different electrode densities (3.4 and 2.8 g/cm(3)), and LiCoO2 with a particle size of 300 nm demonstrated the best rate capability at higher C rates. Upon extended cycling at the 7 C rate, LiCoO2 with a particle size of 300 nm exhibited 87 and 150 mAh/g under 3.4 and 2.8 g/cm(3), respectively.