Actions for Electrochemical Charge Transfer Reaction Kinetics at the Silicon-Liquid Electrolyte Interface [electronic resource].

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Electrochemical Charge Transfer Reaction Kinetics at the Silicon-Liquid Electrolyte Interface [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description
pages A7,129-A7,134 : digital, PDF file
Additional Creators
United States. Department of Energy. Office of Basic Energy. Energy Frontier Research Centers (EFRC), United States. Department of Energy. Office of Basic Energy Sciences, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Since the gravimetric lithiation capacity of silicon is roughly ten times that of graphite, while their mass densities are comparable, for the same particle size the current density required to cycle a silicon electrode at a given C-rate is about ten times greater than that of graphite. Depending on the magnitude of the corresponding Butler-Volmer exchange current density, jo, such high current densities may cause the charge transfer kinetics at the silicon-electrolyte interface to become rate limiting. Previously reported values of jo for Si differ by about 10 orders of magnitude. Here we report jo measurements using electrochemical impedance spectroscopy (EIS) for single crystal electronically conductive silicon wafers with well-defined (100) and (111) orientations and active surface areas. The electrochemical cycling regime was designed to avoid artifacts due to stress-induced surface cracking of Si upon lithiation. The exchange current density of the silicon-electrolyte interface is found to be 0.1 ± 0.01 mA/cm2 when using electrolyte consisting of 1 M LiPF6 in EC/DMC (1/1 by wt) + FEC (10 wt%) + VC (2 wt%). Furthermore, these results are then used to illustrate the dependence of kinetic overpotential on particle size and C-rate for silicon compared to lower volumetric capacity compounds such as graphite.
Report Numbers
E 1.99:1387333
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Note
Published through SciTech Connect.
10/02/2015.
Journal of the Electrochemical Society 162 13 ISSN 0013-4651 AM
Tushar Swamy; Yet -Ming Chiang.
Funding Information
SC0001294
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