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Title: In Situ Potentiodynamic Analysis of the Electrolyte/Silicon Electrodes Interface Reactions - A Sum Frequency Generation Vibrational Spectroscopy Study

The key factor in long-term use of batteries is the formation of an electrically insulating solid layer that allows lithium ion transport but stops further electrolyte redox reactions on the electrode surface, hence solid electrolyte interphase (SEI). In this paper, we have studied a common electrolyte, 1.0 M LiPF 6/ethylene carbonate (EC)/diethyl carbonate (DEC), reduction products on crystalline silicon (Si) electrodes in a lithium (Li) half-cell system under reaction conditions. We employed in situ sum frequency generation vibrational spectroscopy (SFG-VS) with interface sensitivity in order to probe the molecular composition of the SEI surface species under various applied potentials where electrolyte reduction is expected. We found that, with a Si(100)-hydrogen terminated wafer, a Si-ethoxy (Si-OC 2H 5) surface intermediate forms due to DEC decomposition. Our results suggest that the SEI surface composition varies depending on the termination of Si surface, i.e., the acidity of the Si surface. We provide the evidence of specific chemical composition of the SEI on the anode surface under reaction conditions. This supports an electrochemical electrolyte reduction mechanism in which the reduction of the DEC molecule to an ethoxy moiety plays a key role. Finally, these findings shed new light on the formation mechanism of SEImore » on Si anodes in particular and on SEI formation in general.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 138; Journal Issue: 3; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Office (EE-3F); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 25 ENERGY STORAGE
OSTI Identifier:
1379048