A recent publication in Scientific Data introduces a comprehensive vibrational spectroscopy and X-ray diffraction (XRD) database. This library encompasses data for ten compounds identified as key interphase components in lithium-ion batteries (LIBs) and emerging battery technologies. The dataset includes measurements from attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, and XRD.
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Background
Lithium-ion batteries are widely used in consumer electronics, electric vehicles, and energy storage systems due to their energy density, power output, longevity, and cost efficiency. Their potential applications could expand further by improving safety, recyclability, and performance while addressing cost and supply chain challenges.
The solid-electrolyte interphase (SEI) at the anode/electrolyte interface is a key factor influencing battery performance. Similarly, the cathode-electrolyte interphase (CEI) at the cathode/electrolyte interface has become increasingly relevant, particularly when pursuing higher energy densities. Given the overlapping chemical constituents of SEIs and CEIs, the researchers refer to them collectively as electrode-electrolyte interphases (EEIs).
Importantly, the composition of EEIs varies significantly based on manufacturing processes, cycling conditions, and other non-standard physical factors. This variability can complicate the identification of interphase components, which this database aims to address.
Methods
The study investigated ten compounds commonly found in battery interphases: lithium acetate, lithium hydride, lithium carbonate, lithium hexafluorophosphate, lithium fluoride, lithium oxide, nickel(II) fluoride, manganese(II) fluoride, and polyethylene oxide (PEO).
Raman Spectroscopy: Raman spectra were collected using a custom-designed polyether ketone (PEEK) sample chamber with an optical window. This setup minimized external interferences such as fluorescence, glass effects, and surface roughness. The raw Raman data were processed using Gaussian and polynomial fitting to eliminate these background contributions.
X-Ray Diffraction (XRD) Analysis: Samples for XRD were prepared in an argon-filled glovebox to prevent exposure to air and moisture. XRD patterns were recorded across a 2θ range of 10–90 degrees. Data processing involved removing instrumental noise and unwanted background signals, with Gaussian fits used to subtract amorphous contributions from the Kapton overlay.
To ensure consistency and usability, the database incorporates existing information on vibrational modes and diffraction peaks for the analyzed compounds. Each data point was annotated with standardized labels, detailing the type of vibrational mode, the bond or functional group involved, the symmetry of the vibration (for FTIR and Raman), and the Miller indices associated with crystal planes (for XRD).
Data Validation
The experimental protocols were designed to ensure that the compounds remained in their unreacted states during measurements. This was validated by comparing the collected data with results from the literature for both pristine and reacted compounds.
A direct comparison of the ATR-FTIR spectrum for lithium hexafluorophosphate (LiPF6) with existing references demonstrated the effectiveness of the measurement procedures in preventing sample degradation. However, for many other compounds, reference data for pristine and reacted forms were unavailable.
The Raman measurement protocols were similarly validated. For example, the spectrum of lithium hydride showed no peaks at 523 cm−1 (characteristic of Li2O) or in the 250–350 cm-1 range (attributed to LiOH). This confirmed that the oxygen- and water-sensitive compound remained unreacted during the experiments.
The quality of the XRD methods was confirmed using lithium oxide as a test case. The Li2O peaks were clearly identifiable, with only minimal contributions near approximately 33 degrees from the 101 plane of LiOH (likely due to minor impurities in the as-delivered powder). No peaks were observed near approximately 36 degrees from the 110 plane of LiOH·H2O, indicating that the sample was effectively shielded from oxygen and water.
Further confirmation came from lithium hydride data, where the absence of peaks at approximately 33 and approximately 56 degrees in the XRD pattern verified that there was no contamination from LiOH. This reinforced the reliability of the XRD protocols in preserving sample integrity under sensitive conditions.
Data Availability
All presented data can be found in the Dryad data library associated with this work. The online data library contains the final and raw data and the fits subtracted from the raw data during processing. Additionally, a .txt file explaining the complete structure of the database is provided in the repository folder.
The data files are in a .xlsx format, which can be opened using various applications, including Excel and Google Sheets. Additionally, these files can be exported as a .csv or other desirable formats for use in data processing and plotting software.
One Excel workbook is provided for each characterization method (Raman, ATR-FTIR, and XRD). Within each workbook, individual sheets correspond to specific compounds, identified by their chemical formula and name.
For ATR-FTIR and XRD data, an additional sheet compiles all final results, aligned with a common x-axis for easier comparison. In contrast, the raw and final Raman data retain separate wavenumber axes to reflect the differences in measurement scales. Additionally, the XRD file includes a dedicated column listing d-spacing values, calculated using Bragg’s law, to support further analysis.
Journal Reference
Karapin-Springorum, L. et al. (2025). An infrared, Raman, and X-ray database of battery interphase components. Scientific Data. DOI: 10.1038/s41597-024-04236-6, https://www.nature.com/articles/s41597-024-04236-6
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