在阳极材料Li12Si7中离子扩散:超快速的准1D扩散和两个不同的快速3D跳跃过程,分别通过7Li NMR放松度学揭示
Alexander Kuhn1, Puravankara Sreeraj, Rainer Pöttgen
1Institute of Physical Chemistry and Electrochemistry, and ZFM-Center for Solid State Chemistry and New Materials, Leibniz University Hannover, Callinstr. 3-3a, 30167 Hannover, Germany. kuhn@pci.uni-hannover.de
Journal of the American Chemical Society
|June 1, 2011
概括
研究人员使用核磁共振研究了Li(12) Si(7) 中的离子扩散. 他们发现了一个快速的,一维的扩散过程,在低温下在固体中观察到的最快的过程之一.
科学领域:
- 材料科学 材料科学 材料科学
- 固态化学 固态化学
- 电化学 电化学 电化学
背景情况:
- -金属间化合物是离子电池的有希望的阳极材料.
- 晶体Li-Si相作为模型系统,用于研究复杂固体结构中的快速离子扩散.
研究的目的:
- 通过使用先进的NMR技术,研究晶体Li(12) Si(7) 中的Li自我扩散性.
- 描述Li(12) Si(7) 结构中的扩散机制和动力学.
主要方法:
- 使用了 (7) Li 核磁共振 (NMR) 旋转放松 (SLR) 测量.
- 在实验室和旋转参考框架中进行了可变温度和可变频率的NMR实验.
主要成果:
- 在Li(12) Si(7) 内部确定了三种不同的扩散过程.
- 观察到一个高度移动的,一维的扩散过程,在低温下异常快速的离子运动.
- 量化的跳跃率遵循阿雷尼乌斯的行为,从150K的10~5s~-1到425K的10~9s~-1之间.
结论:
- 该研究揭示了一个非常快的,低激活能 (0.18 eV) 一维的Li扩散机制在Li(12)Si(7).
- 这些发现有助于理解复杂固体中的离子运输,并为先进电池材料的设计提供信息.
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