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Multicycle operando Raman spectroscopy reveals reversible and irreversible transitions in LiNiO2 electrodes
Eva Del Campo Ortiz1, Alex R Neale2, Manel Sonni3,4
1Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland. marek.marcinek@pw.edu.pl.
Physical Chemistry Chemical Physics : PCCP
|December 5, 2025
Summary
Operando Raman spectroscopy reveals irreversible changes in lithium nickel oxide (LiNiO2) electrodes during the first cycle, with subsequent reversible shifts indicating phase transitions and lithiation states in lithium-ion cells.
Area of Science:
- Materials Science
- Electrochemistry
- Spectroscopy
Background:
- Lithium nickel oxide (LiNiO2) is a key cathode material for lithium-ion batteries.
- Understanding electrode behavior during cycling is crucial for improving battery performance and longevity.
- Operando techniques are essential for real-time monitoring of electrochemical processes.
Purpose of the Study:
- To investigate the delithiation and lithiation processes of LiNiO2 electrodes during the initial three cycles using operando Raman spectroscopy.
- To correlate observed spectral changes with electrode structural and chemical evolution.
- To optimize the operando electrochemical Raman cell for practical Li-ion battery chemistry.
Main Methods:
- Utilized operando Raman spectroscopy to monitor LiNiO2 electrodes during electrochemical cycling.
- Optimized an electrochemical Raman cell for in-situ characterization of composite electrodes.
- Tracked specific Raman modes (Eg and A1g) to identify changes in electrode structure and composition.
Main Results:
- Localized irreversible changes were observed in LiNiO2, particularly during the first cycle, correlating with initial inefficiencies.
- Subsequent cycles showed reversible band shifts and intensity changes in Raman spectra.
- Trends in band position and intensity were linked to the state of lithiation (Li content) and phase transitions (H1, M, H2, H3).
Conclusions:
- Operando Raman spectroscopy provides valuable insights into the dynamic behavior of LiNiO2 electrodes during cycling.
- First-cycle inefficiencies in LiNiO2 are associated with localized irreversible structural changes.
- The study demonstrates the capability of operando Raman spectroscopy for characterizing Li-ion battery materials and understanding their phase transformations.
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