AVS 63rd International Symposium & Exhibition
    Applied Surface Science Thursday Sessions
       Session AS+SS-ThM

Paper AS+SS-ThM6
In Situ Liquid SIMS Investigation of Chemical Components of the Solid-Electrolyte Interface in Li Ion Batteries

Thursday, November 10, 2016, 9:40 am, Room 101B

Session: Depth Profiling, Buried Interfaces, and 3D Analyses
Presenter: Zihua Zhu, Pacific Northwest National Laboratory
Authors: Z. Zhu, Pacific Northwest National Laboratory
C. Wang, Pacific Northwest National Laboratory
Y. Zhou, Pacific Northwest National Laboratory
D.R. Baer, Pacific Northwest National Laboratory
W. Xu, Pacific Northwest National Laboratory
R. Cao, Pacific Northwest National Laboratory
X. Yu, Pacific Northwest National Laboratory
P. Yan, Pacific Northwest National Laboratory
R. Zhao, Pacific Northwest National Laboratory
Correspondent: Click to Email
Since the birth of Li-ion battery, Solid-Electrolyte Interface (SEI) has been a hot research topic, and numerous efforts have led to some information about its chemical composition, formation mechanism and degradation process. However, critical questions that can enable the design of advance battery systems remain unanswered because it has been very difficult to molecularly examine the SEI layer during battery operation. For example, in situ TEM has been used to study the formation process of the SEI layer in Li ion batteries; however, mostly morphological information, but very limited chemical information is obtained. In situ liquid SIMS was developed in Pacific Northwest National Laboratory (PNNL) in the last several years, and it has proven a very promising new technique to provide both elemental and molecular information at solid-liquid interfaces. In this work, a model Li-ion battery was designed for in situ liquid SIMS analysis of SEI layer. A ~70 nm thick Cu film was deposited onto a SiN membrane, which served as anode. Cathode was traditional LiCoO2. 1.0M LiPF6 in EC (ethylene carbonate)/DMC (dimethyl carbonate) was used as electrolyte. Li2O and LiOH are found in the SEI layer, while very little LiF is observed, indicating LiF is not an important component in the SEI layer. More interestingly, solvent molecules are found in the SEI layer, and the major component is DMC but not EC. In addition, very little PF6- is found in SEI layer. This is the first time that molecular information of the SEI layer is obtained, and the new information will greatly advance understanding formation mechanism and degradation process of SEI layer.