NMR relaxometry as a versatile tool to study Li ion dynamics in potential battery materials

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• 作者：A. Kuhn^a ; ^{kuhn@pci.uni-hannover.de} ; M. Kunze^b ; P. Sreeraj^c ; H.-D. Wiemhö ; fer^c ; V. Thangadurai^d ; M. Wilkening^a ; ^e ; ^{wilkening@pci.uni-hannover.de} ; ^{wilkening@tugraz.at} ; P. Heitjans^a ; ^e ; ^{heitjans@pci.uni-hannover.de}
• 关键词：Li ion dynamics ; NMR spin&ndash ; lattice relaxation ; Battery materials ; Li7La3Zr2O12 ; Li12Si7
• 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：2-8
• 文件大小：383 K

摘要

NMR spin relaxometry is known to be a powerful tool for the investigation of Li⁺ dynamics in (non-paramagnetic) crystalline and amorphous solids. As long as significant structural changes are absent in a relatively wide temperature range, with NMR spin-lattice (as well as spin-spin) relaxation measurements information on Li self-diffusion parameters such as jump rates and activation energies are accessible. Diffusion-induced NMR relaxation rates are governed by a motional correlation function describing the ion dynamics present. Besides the mean correlation rate of the dynamic process, the motional correlation function (i) reflects deviations from random motion (so-called correlation effects) and (ii) gives insights into the dimensionality of the hopping process. In favorable cases, i.e., when temperature- and frequency-dependent NMR relaxation rates are available over a large dynamic range, NMR spin relaxometry is able to provide a comprehensive picture of the relevant Li dynamic processes. In the present contribution, we exemplarily present two recent variable-temperature ⁷Li NMR spin-lattice relaxation studies focussing on Li⁺ dynamics in crystalline ion conductors which are of relevance for battery applications, viz. Li₇ La₃Zr₂O₁₂ and Li₁₂Si₇.