Cryogenic X-ray photoelectron spectroscopy for battery interfaces
Article metadata
Article Date = 22 October 2025
Article URL = https://www.nature.com/articles/s41586-025-09618-3
Article Title = Cryogenic X-ray photoelectron spectroscopy for battery interfaces
Article Image = https://www.nature.com/articles/s41586-025-09618-3
Summary
This Nature paper describes the development and application of cryogenic X-ray photoelectron spectroscopy (cryo-XPS) and an associated cryo-transfer process to analyse battery electrode|electrolyte interphases (SEI/CEI) while preserving volatile and temperature-sensitive species. The authors compare cryo-XPS with conventional room-temperature XPS (RT-XPS) and with cryo-(S)TEM EELS, showing that cryo workflows greatly reduce X-ray- and temperature-induced chemical changes. Time-resolved spectra and control experiments (re-heating, re-cooling, sputtering) demonstrate that cryo-XPS reveals different compositions — including labile Li‑containing compounds — that are lost or transformed during RT analysis. The paper provides experimental protocols, extended data, and source data to support reproducibility.
Key Points
- Cryo-XPS preserves temperature- and X-ray-sensitive species in the SEI/CEI that RT-XPS often alters or eliminates.
- The team developed a cryo-transfer workflow to move samples from electrochemical cells to the XPS instrument without warming, limiting artefacts.
- Time-resolved cryo-XPS shows compositional evolution (F, Li, N, C, O, S regions) and demonstrates which species are stable vs. labile under analysis conditions.
- Comparisons with cryo-STEM EELS corroborate thickness and species assignments, strengthening the compositional interpretation.
- Ar+ sputtering is shown to be destructive; cryo-XPS reduces the need for aggressive sample treatment that can misrepresent interphase chemistry.
- They report correlations between SEI fluorine-to-carbon ratio (F/C) and Coulombic efficiency across multiple electrolytes — linking surface chemistry to electrochemical performance.
Content summary
The authors outline experimental design, including electrochemical formation of SEIs, cryo-preservation, and XPS acquisition at cryogenic temperatures. High-resolution spectra across elemental regions (F 1s, Li 1s, N 1s, C 1s, O 1s, S 2p) are collected time-resolved at 0 and 60 minutes to track evolution under the beam and during controlled warming. Control experiments include cryo-heated-to‑RT-XPS, gradual re-cooling, and unwashed vs rinsed SEI samples to isolate temperature effects.
The main finding is that RT-XPS can induce transformations (including X-ray-induced LiF formation and loss/alteration of volatile or low-binding-energy species), whereas cryo-XPS retains a truer snapshot of the interphase. The paper ties these spectroscopic observations to electrochemical metrics (Coulombic efficiency) and cross-validates some assignments with cryo-(S)TEM EELS. Extensive extended data figures and source data are provided, plus a clear statement that all data required to evaluate conclusions are included in the paper and supplementary information.
Context and relevance
Accurate surface characterisation of battery interphases underpins understanding of lithium metal and high-energy electrodes. XPS is widely used, but RT measurements can misrepresent the real interphase because many SEI components are sensitive to temperature, vacuum and X-ray exposure. By applying cryogenic preservation and transfer, this work reduces measurement-induced artefacts and challenges some prior XPS-based interpretations. The approach is highly relevant to researchers working on lithium metal anodes, electrolyte formulation, interphase engineering and anyone using surface-sensitive spectroscopy to infer mechanisms in electrochemical systems. It also has implications for re-evaluating legacy XPS datasets where labile species may have been lost during analysis.
Author note (punchy)
Punchy: If you study battery interphases or use XPS to claim what’s on a lithium surface, this paper matters. The authors show that a lot of what we thought we ‘saw’ can change just because of the measurement. Read the detailed methods — they give a practical cryo-transfer recipe and cross-checks that could save you from drawing the wrong chemical conclusions.
Why should I read this?
Short version: you want the real chemistry, not the chemistry the X-ray beam or warm vacuum made up. This paper shows how cryo-XPS keeps fragile SEI species intact so you can link what’s actually on the surface to battery performance — and it gives practical steps to do it. If you care about accurate interphase chemistry (or avoiding chasing artefacts), skim the figures and methods — they’ve done the tedious work so you don’t have to.