Cryogenic X-ray photoelectron spectroscopy for battery interfaces.
basic_science · Level V
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- Record sourced from PubMed, PMID 41125775.
- Also identified by DOI 10.1038/s41586-025-09618-3.
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Abstract
Understanding the chemical environment of pristine interfaces is a long-sought goal in electrochemistry, materials science and surface science. A substantial understanding of one such interface, the solid electrolyte interphase (SEI) in lithium anodes, originates from X-ray photoelectron spectroscopy (XPS)<sup>1,2</sup>. However, room temperature (RT) combined with ultrahigh vacuum (UHV) can induce major SEI evolution from reactions and volatilization during XPS<sup>1,2</sup>. Thus, a technique is necessary for SEI stabilization. Here we develop cryogenic (cryo)-XPS with immediate plunge freezing and demonstrate SEI preservation. We discover substantially different SEI speciation and a thicker pristine SEI with cryo-XPS, free from RT-associated thickness reduction and alterations to important species, including LiF and Li<sub>2</sub>O, in UHV. This new access to pristine SEI composition enables performance correlations across diverse electrolyte chemistries. Primarily, we highlight the necessity of studying sensitive interfaces under cryogenic conditions.