Hood Zachary D, Chen Xi, Sacci Robert L, Liu Xiaoming, Veith Gabriel M, Mo Yifei, Niu Junjie, Dudney Nancy J, Chi Miaofang
School of Chemistry and Biochemistry, Georgia Institute of Technology Atlanta, Georgia 30332-0400, United States.
Department of Materials Science and Engineering, CEAS, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States.
Nano Lett. 2021 Jan 13;21(1):151-157. doi: 10.1021/acs.nanolett.0c03438. Epub 2020 Dec 18.
Li phosphorus oxynitride (LiPON) is one of a very few solid electrolytes that have demonstrated high stability against Li metal and extended cyclability with high Coulombic efficiency for all solid-state batteries (ASSBs). However, theoretical calculations show that LiPON reacts with Li metal. Here, we utilize electron microscopy to observe the dynamic evolutions at the LiPON-Li interface upon contacting and under biasing. We reveal that a thin interface layer (∼60 nm) develops at the LiPON-Li interface upon contact. This layer is composed of conductive binary compounds that show a unique spatial distribution that warrants an electrochemical stability of the interface, serving as an effective passivation layer. Our results explicate the excellent cyclability of LiPON and reconcile the existing debates regarding the stability of the LiPON-Li interface, demonstrating that, though glassy solid electrolytes may not have a perfect initial electrochemical window with Li metal, they may excel in future applications for ASSBs.
锂磷氮氧化物（LiPON）是极少数对锂金属具有高稳定性且在所有固态电池（ASSB）中具有高库仑效率的长循环稳定性的固体电解质之一。然而，理论计算表明LiPON会与锂金属发生反应。在此，我们利用电子显微镜观察LiPON与锂接触及偏置时LiPON-锂界面的动态演变。我们发现接触时LiPON-锂界面会形成一个薄的界面层（约60纳米）。该层由导电二元化合物组成，其独特的空间分布确保了界面的电化学稳定性，起到了有效的钝化层作用。我们的结果解释了LiPON出色的循环稳定性，并调和了关于LiPON-锂界面稳定性的现有争议，表明尽管玻璃态固体电解质与锂金属可能没有完美的初始电化学窗口，但它们在未来ASSB应用中可能表现出色。
