TY - JOUR
T1 - Elastic-Plastic Deformation of a Solid Electrolyte Interface Formed by Reduction of Fluoroethylene Carbonate
T2 - A Nanoindentation and Finite Element Analysis Study
AU - Kamikawa, Yuki
AU - Amezawa, Koji
AU - Terada, Kenjiro
N1 - Publisher Copyright:
©
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/10/15
Y1 - 2020/10/15
N2 - The precise mechanical property evaluation of a solid electrolyte interface (SEI) is crucial for the mechanical stability of the SEI on silicon anodes, which significantly expand during lithiation. Herein, cyclic loading tests and numerical methods were used to quantify the elastoplasticity and viscoelasticity of SEIs and the effects of the stress field in a silicon anode material below the SEI to precisely evaluate the elastic modulus of the SEI. Instrumented nanoindentation was used to quantitatively observe the indentation force response on the heterogeneous surface of composite electrodes. The mechanical properties of the SEI with a nanothin film structure probed by a simple analytical model assuming perfect elastic and homogeneous mechanical properties in a domain subjected to the indentation force resulted in significant elastic modulus overestimation. The substrate effect was significant, especially for reduced SEI thickness, and could cause an "apparently"mechanically bilayered structure of the SEI with a hard inorganic inner layer and a soft outer polymeric layer. The elastic modulus of the SEI formed in fluoroethylene carbonate (FEC) electrolyte (3.7 GPa) agreed with that previously predicted from the mechanical properties of cross-linked polymers in the SEI formed from a FEC electrolyte and supported the recent solid-state NMR results reporting the existence of polymeric species on the interfacial region of the FEC-SEI and the silicon anode.
AB - The precise mechanical property evaluation of a solid electrolyte interface (SEI) is crucial for the mechanical stability of the SEI on silicon anodes, which significantly expand during lithiation. Herein, cyclic loading tests and numerical methods were used to quantify the elastoplasticity and viscoelasticity of SEIs and the effects of the stress field in a silicon anode material below the SEI to precisely evaluate the elastic modulus of the SEI. Instrumented nanoindentation was used to quantitatively observe the indentation force response on the heterogeneous surface of composite electrodes. The mechanical properties of the SEI with a nanothin film structure probed by a simple analytical model assuming perfect elastic and homogeneous mechanical properties in a domain subjected to the indentation force resulted in significant elastic modulus overestimation. The substrate effect was significant, especially for reduced SEI thickness, and could cause an "apparently"mechanically bilayered structure of the SEI with a hard inorganic inner layer and a soft outer polymeric layer. The elastic modulus of the SEI formed in fluoroethylene carbonate (FEC) electrolyte (3.7 GPa) agreed with that previously predicted from the mechanical properties of cross-linked polymers in the SEI formed from a FEC electrolyte and supported the recent solid-state NMR results reporting the existence of polymeric species on the interfacial region of the FEC-SEI and the silicon anode.
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U2 - 10.1021/acs.jpcc.0c06420
DO - 10.1021/acs.jpcc.0c06420
M3 - Article
AN - SCOPUS:85096614900
VL - 124
SP - 22488
EP - 22495
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 41
ER -