Quantification of the Mass and Viscoelasticity of Interfacial Films on Tin Anodes Using EQCM-D

Journal Article · Mon Nov 23 23:00:00 EST 2015 · ACS Applied Materials and Interfaces

DOI:https://doi.org/10.1021/acsami.5b07966· OSTI ID:1371014

Yang, Zhenzhen ^[1]; Dixon, Matthew C. ^[2]; Erck, Robert A. ^[1]; Trahey, Lynn ^[1]

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1. Argonne National Lab. (ANL), Argonne, IL (United States)
2. Biolin Scientific, Inc., Linthicum Heights, MD (United States)

Electrochemical quartz crystal microbalance coupled with dissipation (EQCM-D) is employed to explore the solid electrolyte interphase (SEI) formation and Li insertion/deinsertion into thin film electrodes of tin. Due to the frequency change we find that the initial SEI formation process is rapid before Li insertion but varies significantly with increasing concentration of the additive fluoroethylene carbonate (FEC) in the electrolyte. The extent of dissipation, which represents the film rigidity, increases with cycle number, reflecting film thickening and softening. Dissipation values are almost twice as large in the baseline electrolyte (1.2 M LiPF₆ in 3:7 wt % ethylene carbonate:ethyl methyl carbonate), indicating the film in baseline electrolyte is roughly twice as soft as in the FEC-containing cells. More importantly, we detail how quantitative data about mass, thickness, shear elastic modulus, and shear viscosity in a time-resolved manner can be obtained from the EQCM-D response. These parameters were extracted from the frequency and dissipation results at multiple harmonics using the Sauerbrey and Voigt viscoelastic models. From these modeled results we show the dynamic mass changes for each half cycle. We also demonstrate that different amounts of FEC additive influence the SEI formation behavior and result in differences in the estimated mass, shear modulus and viscosity. After three cycles, the film in baseline electrolyte exhibits a 1.2 times larger mass change compared with the film in the FEC-containing electrolyte. The shear elastic modulus of films formed in the presence of FEC is larger than in the baseline electrolyte at early stages of lithiation. Also with lithiation is a marked increase in film viscosity, which together point to a much stiffer and more homogeneous SEI formed in the presence of FEC.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Center for Electrical Energy Storage (CEES)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1371014
• Journal Information: ACS Applied Materials and Interfaces, Journal Name: ACS Applied Materials and Interfaces Journal Issue: 48 Vol. 7; ISSN 1944-8244
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
EQCM-D
FEC additive
SEI viscoelasticity
Voigt model
electrochemical quartz crystal microbalance
tin anode