Al/Ga 掺杂的 Li7La3Zr2O12 (LLZO) 石榴石作为锂离子固态电池电解质：局部配位环境的原子洞察及其对 17O、27Al 和 71Ga 核磁共振谱的影响,Journal of the American Chemical Society

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Al/Ga 掺杂的 Li7La3Zr2O12 (LLZO) 石榴石作为锂离子固态电池电解质：局部配位环境的原子洞察及其对 17O、27Al 和 71Ga 核磁共振谱的影响
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-01-17 , DOI: 10.1021/jacs.9b12685
Bora Karasulu ₁ , Steffen P Emge ₂ , Matthias F Groh ₂ , Clare P Grey ₂ , Andrew J Morris ₃

Affiliation

Li7La3Zr2O12 (LLZO) 石榴石由于其高稳定性和离子电导率，是下一代全固态锂离子电池应用中最有前途的固体电解质之一。为了帮助确定不同超价掺杂剂对晶体结构和位点偏好的影响，我们结合了固态 17O、27Al 和 71Ga 魔角旋转 (MAS) NMR 光谱和密度泛函理论 (DFT) 计算。对未掺杂和 Al 和/或 Ga 掺杂 LLZO 变体的基于 DFT 的缺陷配置分析揭示了原子的局部网络与观察到的 NMR 信号之间的相互作用。具体来说，在 27Al 和 71Ga NMR 谱中观察到的两个特征是由 4 倍配位 Li1/24d 位点（而不是其他 Li2/96h 或 La 位点的掺杂）内的多面体配位/位点对称性的偏差引起的以及与这些掺杂位点共享氧原子的相邻 Li2 位点的数量。尖锐的 27Al 和 71Ga 共振来自位于高度对称四面体 24d 位点的掺杂剂，该位点具有四个共享角的 LiO4 邻居，而更广泛的特征源自高度扭曲的掺杂剂位点，其相邻的 LiO4 较少或没有。建立了 27Al/71Ga 四极耦合尺寸与掺杂位点畸变（即 XO4/XO5/XO6，其中 X = {Al/Ga}）之间的相关性。

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Al/Ga-doped Li7La3Zr2O12 (LLZO) Garnets as Li-ion Solid-State Battery Electrolytes: Atomistic Insights into Local Coordination Environments and their Influence on 17O, 27Al and 71Ga NMR Spectra

Li7La3Zr2O12 (LLZO) garnets are among the most promising solid electrolytes for next-generation all-solid-state Li-ion battery applications due to their high stabilities and ionic conductivities. To help determine the influence of different supervalent dopants on the crystal structure and site preferences, we combine solid-state 17O, 27Al, and 71Ga magic angle spinning (MAS) NMR spectroscopy and density-functional theory (DFT) calculations. DFT-based defect configuration analysis for the undoped and Al and/or Ga-doped LLZO variants uncovers an interplay between the local network of atoms and the observed NMR signals. Specifically, the two characteristic features observed in both 27Al and 71Ga NMR spectra result from both the deviations in the polyhedral coordination/site-symmetry within the 4-fold coordinated Li1/24d sites (rather than the doping of the other Li2/96h or La sites) and with the number of occupied adjacent Li2 sites that share oxygen atoms with these dopant sites. The sharp 27Al and 71Ga resonances arise from dopants located at a highly symmetric tetrahedral 24d site with four corner-sharing LiO4 neighbors, whereas the broader features originate from highly distorted dopant sites with fewer or no immediate LiO4 neighbors. A correlation between the size of the 27Al/71Ga quadrupolar coupling and the distortion of the doping sites (viz. XO4/XO5/XO6 with X = {Al/Ga}) is established. 17O MAS NMR spectra for these systems provide insights into the oxygen connectivity network: 17O signals originating from the dopant-coordinating oxygens are resolved and used for further characterization of the microenvironments at the dopant and other sites.

更新日期：2020-01-17

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