Ion Dynamics in Li2CO3 Studied by Solid-State NMR and First-Principles Calculations

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• 作者：Matthew T. Dunstan ; John M. Griffin ; Fr茅d茅ric Blanc ; Michal Leskes ; Clare P. Grey
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：October 29, 2015
• 年：2015
• 卷：119
• 期：43
• 页码：24255-24264
• 全文大小：497K
• ISSN：1932-7455

文摘

Novel lithium-based materials for carbon capture and storage (CCS) applications have emerged as a promising class of materials for use in CO₂ looping, where the material reacts reversibly with CO₂ to form Li₂CO₃, among other phases depending on the parent phase. Much work has been done to try and understand the origin of the continued reactivity of the process even after a layer of Li₂CO₃ has covered the sorbent particles. In this work, we have studied the lithium and oxygen ion dynamics in Li₂CO₃ over the temperature range of 293鈥?73 K in order to elucidate the link between dynamics and reactivity in this system. We have used a combination of powder X-ray diffraction, solid-state NMR spectroscopy, and theoretical calculations to chart the temperature dependence of both structural changes and ion dynamics in the sample. These methods together allowed us to determine the activation energy for both lithium ion hopping processes and carbonate ion rotations in Li₂CO₃. Importantly, we have shown that these processes may be coupled in this material, with the initial carbonate ion rotations aiding the subsequent hopping of lithium ions within the structure. Additionally, this study shows that it is possible to measure dynamic processes in powder or crystalline materials indirectly through a combination of NMR spectroscopy and theoretical calculations.