Hu Xiangchen, Chen Shaojie, Wang Zeyu, Chen Yu, Yuan Biao, Zhang Yue, Liu Wei, Yu Yi
School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China.
Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, People's Republic of China.
Nano Lett. 2023 Feb 8;23(3):887-894. doi: 10.1021/acs.nanolett.2c04135. Epub 2023 Jan 17.
The microstructure of the LiLaZrO (LLZO) garnet solid electrolyte is critical for its performance in all-solid-state lithium-ion battery. During conventional high-temperature sintering, second phases are generated at the grain boundaries due to the reaction between sintering aids and LLZO, which have an enormous effect on the performances of LLZO. However, a detailed structure study of the second phases and their impact on physical properties is lacking. Here, crystal structures of the second phases in LLZO pellets are studied in detail by transmission electron microscopy. Three different crystal structures of Li-Al-O second phases, γ-LiAlO, α-LiAlO, and β-LiAlO were identified, and atomic-scale lattice information was obtained by applying low-dose high-resolution imaging for these electron-beam-sensitive second phases. On this basis, the structure-property relationship of these structures was explored. It was found that sintering aids with a higher Li/Al ratio are beneficial to form Li-rich second phases, which result in more highly ionic conductive LLZO.
LiLaZrO（LLZO）石榴石固态电解质的微观结构对其在全固态锂离子电池中的性能至关重要。在传统高温烧结过程中，由于烧结助剂与LLZO之间的反应，在晶界处会生成第二相，这对LLZO的性能有巨大影响。然而，目前缺乏对第二相的详细结构研究及其对物理性能影响的研究。在此，通过透射电子显微镜对LLZO颗粒中第二相的晶体结构进行了详细研究。鉴定出了Li-Al-O第二相的三种不同晶体结构，即γ-LiAlO、α-LiAlO和β-LiAlO，并通过对这些对电子束敏感的第二相应用低剂量高分辨率成像获得了原子尺度的晶格信息。在此基础上，探索了这些结构的结构-性能关系。发现具有较高Li/Al比的烧结助剂有利于形成富锂第二相，从而导致LLZO具有更高的离子导电性。
