AVS 63rd International Symposium & Exhibition
    In-Situ and Operando Spectroscopy and Microscopy for Catalysts, Surfaces, & Materials Focus Topic Friday Sessions
       Session IS-FrM

Paper IS-FrM7
In Situ Molecular Characterization of the Solid-Electrolyte Interface on Lithium Metal Anode

Friday, November 11, 2016, 10:20 am, Room 101C

Session: In situ Characterization of Nanomaterials
Presenter: Xiaofei Yu, Pacific Northwest National Laboratory
Authors: Y. Zhou, Pacific Northwest National Laboratory
X. Yu, Pacific Northwest National Laboratory
R. Cao, Pacific Northwest National Laboratory
W. Xu, Pacific Northwest National Laboratory
M. Su, Pacific Northwest National Laboratory
Z. Xu, Pacific Northwest National Laboratory
D.R. Baer, Pacific Northwest National Laboratory
C. Wang, Pacific Northwest National Laboratory
Z. Zhu, Pacific Northwest National Laboratory
Correspondent: Click to Email
Currently, the main stream anode material in Li ion battery industry is graphite. Though it has been a great commercial success, the energy density of graphite-based Li-ion batteries will reach their limit soon. Li metal is an ideal anode material for next generation rechargeable Li batteries because of its extremely high theoretical specific capacity and very low negative electrochemical potential. It has been over 40 years since the first attempt of using Li metal as an anode; however, large-scale commercial applications are still not achieved due to a few challenges, such as dendritic Li growth and limited Columbic efficiency. Recent years, it has been reported that highly concentrated electrolytes, such as 4.0 M lithium bis(fluorosulfonyl)imide (LiFSI ) in 1,2-dimethoxyethane (DME), can result in the dendrite-free plating of Li metal and with high Columbic efficiency. However, the detailed mechanism is not clear. In this research, in situ liquid SIMS was used to molecularly characterize the structure of the Solid-Electrolyte Interfaces (SEI) formed in 1.0 M and 4.0 M LiFSI in DME. The thickness of the SEI in 4.0 M electrolyte is thinner than that in 1.0 M electrolyte. More importantly, less solvent molecules (DME) and Li metal residuals were found in the SEI layer formed in 4.0 M electrolyte. In addition, more F- was found in the SEI layer formed in 4.0 M electrolyte, indicating that more LiF stays in the SEI layer formed in 4.0 M electrolyte. Our data suggest that the residual solvent molecules (DME) in the SEI layer may play an important role in formation of dendrite and decreasing of Columbic efficiency.