Multi-Modal Characterization Methods of Solid-Electrolyte Interphase in Silicon-Graphite Composite Electrodes

Zoey Huey, Yeyoung Ha, Sarah Frisco, Andrew Norman, Glenn Teeter, Chun Sheng Jiang, Steven C. DeCaluwe

Research output: Contribution to journalArticlepeer-review

4 Scopus Citations

Abstract

Composite silicon-graphite (Si-Gr) anodes can improve battery energy density, due to Si's high gravimetric capacity, while mitigating mechanical degradation of the anode and solid-electrolyte interphase (SEI) caused by Si volumetric expansion. Optimizing these anodes is challenging, in part due to difficulty characterizing the SEI structure and composition. In this work, we present multi-modal characterization of the SEI on composite Si-Gr anodes to relate SEI chemical composition and structure to functional properties. Discrepancies in elemental concentrations from X-ray photoelectron spectroscopy, Auger electron spectroscopy, and energy-dispersive X-ray spectroscopy (EDS) are attributed to varying information depth and lateral resolution of the individual probes. However, by combining quantitative composition information with spatially resolved element mapping from scanning transmission electron microscopy, EDS, and electron energy loss spectroscopy, a holistic picture of the SEI emerges. We observe the bilayer SEI structure and a direct correlation between elemental Li and F, suggesting that most Li in the SEI exists as lithium fluoride (LiF). Further, LiF concentration is directly proportional to the maximum SEI resistivity, as determined by scanning spreading resistance microscopy. Lastly, there is an inverse relationship between lithium carbonate and LiF concentration in the SEI, providing insight into the detailed chemistry of SEI formation and evolution.

Original languageAmerican English
Article number232804
Number of pages10
JournalJournal of Power Sources
Volume564
DOIs
StatePublished - 30 Apr 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors

NREL Publication Number

  • NREL/JA-5K00-84226

Keywords

  • Lithium ion batteries
  • Silicon electrodes
  • Solid electrolyte interphase
  • Surface characterization

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