Study of local structure and Li dynamics in () using ⁶Li and ⁷Li NMR spectroscopy

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• 作者：Holger Hain ; Marco Scheuermann ; Ralf Heinzmann ; Linda W&uuml ; nsche ; Horst Hahn ; Sylvio Indris ; ^{sylvio.indris@kit.edu}
• 关键词：Li-ion batteries ; Anode materials ; Intercalation mechanism ; Li ion dynamics ; Spin diffusion
• 刊名：Solid State Nuclear Magnetic Resonance
• 出版年：2012
• 期刊代码：83_09262040
• 类别：ce
• 出版时间：April, 2012
• 卷：42
• 期：Complete
• 页码：9-16
• 文件大小：477 K

摘要

We studied the local structure and the Li ion dynamics in electrochemically and chemically prepared with . We used magic-angle spinning ⁷Li NMR on samples with different Li contents to investigate the sites that are occupied/emptied during Li insertion/removal. While the electrochemical measurements show a lithium insertion in two steps, 1D MAS NMR as a function of the lithium content shows that the overall spectral evolution observed during lithium insertion is inverted during lithium removal. Thereby the second insertion step is associated with an increased structural disorder. For samples with x=0, 2, 3, and about 5, we performed temperature-dependent measurements of the ⁷Li NMR relaxation rates , , and to study the dynamics of the Li ions. For the samples with x=0, 2, and 3, activation energies of (0.45卤0.1) eV were obtained. The highest mobility of the Li ions is observed for the samples with x=2 and 3. Results from ⁶Li and ⁷Li 2D exchange MAS NMR spectroscopy on samples with x=2 and 4 show that magnetization transfer for ⁷Li below 323 K is dominated by spin diffusion.