School of Materials Science and Engineering, Materials Genome Institute, Shanghai University , Shanghai 200444, China.
Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China.
ACS Appl Mater Interfaces. 2018 Feb 14;10(6):5978-5983. doi: 10.1021/acsami.7b17276. Epub 2018 Jan 30.
The garnet ionic conductor is one of the promising candidate electrolytes for all-solid-state secondary lithium batteries, thanks to its high lithium ion conductivity and good thermal and chemical stability. However, its microstructure is difficult to approach because it is very sensitive to the inquisitive electron beam. In this study based on a scanning electron microscope (SEM), we found that the electron beam expulses the lithium out of LiLaZrTaO (LLZTO), and the expulsed zone expands to where a stationary beam could extend and penetrate. The expulsion of metallic lithium was confirmed by its oxidation reaction after nitrogen inflow into the SEM. This phenomenon may provide us an effective probe to peer into the conductive nature of this electrolyte. A frame-scan scheme is employed to measure the expulsion rate by controllable and more uniform incidence of electrons. Lithium accumulation processes are continuously recorded and classified into four modes by fitting its growth behaviors into a dynamic equation that is mainly related to the initial ion concentration and ion migration rate in the electrolyte. These results open a novel possibility of using the SEM probe to gain dynamic information on ion migration and lithium metal growth in solid materials.
石榴石型离子导体由于其高锂离子电导率、良好的热稳定性和化学稳定性，成为全固态二次锂电池有前途的候选电解质之一。然而，由于其对电子束非常敏感，因此很难接近其微观结构。在这项基于扫描电子显微镜（SEM）的研究中，我们发现电子束会将锂离子从 LiLaZrTaO（LLZTO）中逐出，逐出区域会扩展到固定电子束可以延伸和穿透的位置。氮气流入 SEM 后，通过其氧化反应证实了金属锂的逐出。这种现象可能为我们提供了一种有效的探针，以深入了解这种电解质的导电性质。采用逐行扫描方案，通过可控和更均匀的电子入射来测量逐出率。通过将其生长行为拟合到主要与电解质中初始离子浓度和离子迁移率相关的动力学方程中，连续记录并将锂积累过程分类为四种模式。这些结果为使用 SEM 探针获取固态材料中离子迁移和金属锂生长的动态信息开辟了新的可能性。
