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Title: Chemical Evolution in Silicon–Graphite Composite Anodes Investigated by Vibrational Spectroscopy

Abstract

Silicon–graphite composites are under development for the next generation of high-capacity lithium-ion anodes, and vibrational spectroscopy is a powerful tool to identify the different mechanisms that contribute to performance loss. With alloy anodes, the underlying causes of cell failure are significantly different in half-cells with lithium metal counter electrodes compared to full cells with standard cathodes. However, most studies which take advantage of vibrational spectroscopy have only examined half-cells. In this work, a combination of FTIR and Raman spectroscopy describes several factors that lead to degradation in full pouch cells with LiNi 0.5Mn 0.3Co 0.2O 2 (NMC532) cathodes. The spectroscopic signatures evolve after longer term cycling compared to the initial formation cycles. Several side-reactions that consume lithium ions have clear FTIR signatures, and comparison to a library of reference compounds facilitates identification. Raman microspectroscopy combined with mapping shows that the composite anodes are not homogeneous but segregate into graphite-rich and silicon-rich phases. Lithiation does not proceed uniformly either. A basis analysis of Raman maps identifies electrochemically inactive regions of the anodes. In conclusion, the spectroscopic results presented here emphasize the importance of improving electrode processing and SEI stability to enable practical composite anodes with high silicon loadings.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
OSTI Identifier:
1440831
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 10; Journal Issue: 22; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; anode; composite; FTIR; graphite; heterogeneity; lithium-ion battery; Raman; silicon

Citation Formats

Ruther, Rose E., Hays, Kevin A., An, Seong Jin, Li, Jianlin, Wood, III, David L., and Nanda, Jagjit. Chemical Evolution in Silicon–Graphite Composite Anodes Investigated by Vibrational Spectroscopy. United States: N. p., 2018. Web. doi:10.1021/acsami.8b02197.
Ruther, Rose E., Hays, Kevin A., An, Seong Jin, Li, Jianlin, Wood, III, David L., & Nanda, Jagjit. Chemical Evolution in Silicon–Graphite Composite Anodes Investigated by Vibrational Spectroscopy. United States. doi:10.1021/acsami.8b02197.
Ruther, Rose E., Hays, Kevin A., An, Seong Jin, Li, Jianlin, Wood, III, David L., and Nanda, Jagjit. Thu . "Chemical Evolution in Silicon–Graphite Composite Anodes Investigated by Vibrational Spectroscopy". United States. doi:10.1021/acsami.8b02197.
@article{osti_1440831,
title = {Chemical Evolution in Silicon–Graphite Composite Anodes Investigated by Vibrational Spectroscopy},
author = {Ruther, Rose E. and Hays, Kevin A. and An, Seong Jin and Li, Jianlin and Wood, III, David L. and Nanda, Jagjit},
abstractNote = {Silicon–graphite composites are under development for the next generation of high-capacity lithium-ion anodes, and vibrational spectroscopy is a powerful tool to identify the different mechanisms that contribute to performance loss. With alloy anodes, the underlying causes of cell failure are significantly different in half-cells with lithium metal counter electrodes compared to full cells with standard cathodes. However, most studies which take advantage of vibrational spectroscopy have only examined half-cells. In this work, a combination of FTIR and Raman spectroscopy describes several factors that lead to degradation in full pouch cells with LiNi0.5Mn0.3Co0.2O2 (NMC532) cathodes. The spectroscopic signatures evolve after longer term cycling compared to the initial formation cycles. Several side-reactions that consume lithium ions have clear FTIR signatures, and comparison to a library of reference compounds facilitates identification. Raman microspectroscopy combined with mapping shows that the composite anodes are not homogeneous but segregate into graphite-rich and silicon-rich phases. Lithiation does not proceed uniformly either. A basis analysis of Raman maps identifies electrochemically inactive regions of the anodes. In conclusion, the spectroscopic results presented here emphasize the importance of improving electrode processing and SEI stability to enable practical composite anodes with high silicon loadings.},
doi = {10.1021/acsami.8b02197},
journal = {ACS Applied Materials and Interfaces},
number = 22,
volume = 10,
place = {United States},
year = {Thu May 24 00:00:00 EDT 2018},
month = {Thu May 24 00:00:00 EDT 2018}
}

Journal Article:
Free Publicly Available Full Text
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