In Situ ATR-FTIR Study of the Cathode–Electrolyte Interphase: Electrolyte Solution Structure, Transition Metal Redox, and Surface Layer Evolution

Bertrand J. Tremolet de Villers, Seong Min Bak, Junghoon Yang, Sang Don Han

Research output: Contribution to journalArticlepeer-review


We present a study of the lithium nickel manganese cobalt oxide (LiNi0.6Mn0.2Co0.2O2, NMC622) cathode-electrolyte interphase (CEI) during galvanostatic charging and discharging using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) methods to investigate the voltage dependent electrolyte solution structure changes at the interface, transition metal (TM) redox chemistry, and cathode/electrolyte interfacial layer evolution. Our in situ cell design provides both reliable electrochemical device testing and strong FTIR vibrational absorption signals near the cathode surface. Specifically, advanced spectral analysis elucidates changes of near-surface Li+ ion (de)solvation by solvent molecules during galvanostatic cycling. Moreover, cathode metal-oxygen vibrational absorptions, sensitive to TM redox behaviors and subsequent local structural variations, were correlated to cathode de-lithiation (and lithiation) and electrolyte solution structure changes. In addition, we have detected the formation and evolution of a CEI surface layer on the NMC622 cathode that contributes to the cell's capacity fade.

Original languageEnglish
Pages (from-to)778-784
Number of pages7
JournalBatteries and Supercaps
Issue number5
Publication statusPublished - 2021 May

Bibliographical note

Funding Information:
This work was authored in part by Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory (NREL) for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Support from the Vehicle Technologies Office (VTO), Hybrid Electric Systems Program, David Howell (Manager), Battery R&D, Peter Faguy (Technology Manager), at the U.S. DOE, Office of Energy Efficiency and Renewable Energy, is gratefully acknowledged. The electrode active materials used in this article were synthesized at Argonne's Cell Analysis, Modeling and Prototyping (CAMP) Facility. Funding for in situ ATR-FTIR characterization provided in part by the Laboratory Directed Research and Development (LDRD) Program at NREL. The XAS research used beamline 7-BM (QAS) of the National Synchrotron Light Source II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory (BNL) under Contract No. DE-SC0012704. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.

Publisher Copyright:
© 2020 Wiley-VCH GmbH

All Science Journal Classification (ASJC) codes

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering
  • Electrochemistry


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