Electrochemical Charge Transfer Reaction Kinetics at the Silicon-Liquid Electrolyte Interface
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
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.
- Research Organization:
- Energy Frontier Research Centers (EFRC), Washington, D.C. (United States). Northeastern Center for Chemical Energy Storage (NECCES)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0001294
- OSTI ID:
- 1387333
- Journal Information:
- Journal of the Electrochemical Society, Vol. 162, Issue 13; Related Information: NECCES partners with Stony Brook University (lead); Argonne National Laboratory; Binghamton University; Brookhaven National University; University of California, San Diego; University of Cambridge, UK; Lawrence Berkeley National Laboratory; Massachusetts Institute of Technology; University of Michigan; Rutgers University; ISSN 0013-4651
- Publisher:
- The Electrochemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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