Sebti Elias, Evans Hayden A, Chen Hengning, Richardson Peter M, White Kelly M, Giovine Raynald, Koirala Krishna Prasad, Xu Yaobin, Gonzalez-Correa Eliovardo, Wang Chongmin, Brown Craig M, Cheetham Anthony K, Canepa Pieremanuele, Clément Raphaële J
Materials Department, University of California, Santa Barbara, California 93106, United States.
Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States.
J Am Chem Soc. 2022 Apr 6;144(13):5795-5811. doi: 10.1021/jacs.1c11335. Epub 2022 Mar 24.
In the pursuit of urgently needed, energy dense solid-state batteries for electric vehicle and portable electronics applications, halide solid electrolytes offer a promising path forward with exceptional compatibility against high-voltage oxide electrodes, tunable ionic conductivities, and facile processing. For this family of compounds, synthesis protocols strongly affect cation site disorder and modulate Li mobility. In this work, we reveal the presence of a high concentration of stacking faults in the superionic conductor LiYCl and demonstrate a method of controlling its Li conductivity by tuning the defect concentration with synthesis and heat treatments at select temperatures. Leveraging complementary insights from variable temperature synchrotron X-ray diffraction, neutron diffraction, cryogenic transmission electron microscopy, solid-state nuclear magnetic resonance, density functional theory, and electrochemical impedance spectroscopy, we identify the nature of planar defects and the role of nonstoichiometry in lowering Li migration barriers and increasing Li site connectivity in mechanochemically synthesized LiYCl. We harness paramagnetic relaxation enhancement to enable Y solid-state NMR and directly contrast the Y cation site disorder resulting from different preparation methods, demonstrating a potent tool for other researchers studying Y-containing compositions. With heat treatments at temperatures as low as 333 K (60 °C), we decrease the concentration of planar defects, demonstrating a simple method for tuning the Li conductivity. Findings from this work are expected to be generalizable to other halide solid electrolyte candidates and provide an improved understanding of defect-enabled Li conduction in this class of Li-ion conductors.
在寻求用于电动汽车和便携式电子设备应用的急需的、能量密度高的固态电池时，卤化物固体电解质提供了一条有前景的前进道路，它与高压氧化物电极具有出色的兼容性、可调的离子电导率以及易于加工。对于这类化合物，合成方案强烈影响阳离子位点无序性并调节锂的迁移率。在这项工作中，我们揭示了超离子导体LiYCl中存在高浓度的堆垛层错，并展示了一种通过在特定温度下进行合成和热处理来调节缺陷浓度从而控制其锂电导率的方法。利用可变温度同步加速器X射线衍射、中子衍射、低温透射电子显微镜、固态核磁共振、密度泛函理论和电化学阻抗谱的互补见解，我们确定了平面缺陷的性质以及非化学计量在降低锂迁移势垒和增加机械化学合成的LiYCl中锂位点连通性方面的作用。我们利用顺磁弛豫增强来实现钇的固态核磁共振，并直接对比不同制备方法导致的钇阳离子位点无序性，展示了一种对研究含钇成分的其他研究人员来说很有效的工具。通过在低至333 K（60°C）的温度下进行热处理，我们降低了平面缺陷的浓度，展示了一种调节锂电导率的简单方法。这项工作的发现有望推广到其他卤化物固体电解质候选物，并增进对这类锂离子导体中由缺陷实现的锂传导的理解。
