arXiv subjects

Stéphanie Belin

Publications and source records attributed to Stéphanie Belin.

5 recordsLinked to original sources

arXiv2026

Spatially inhomogeneous delithiation in LiNiO2 positive electrode: the effect of X-rays dose

Operando synchrotron X-ray techniques have become essential tools for investigating rechargeable batteries as they provide real-time insights into electrochemical processes. However, the high brilliance of synchrotron radiation can alter the electrochemical mechanisms within the battery, thereby compromising the reliability and reproducibility of operando measurements. In this study, we introduce a novel methodology that directly correlates the local X-ray dose with the Ni4+/Ni3+ redox activity in a LiNiO2 positive electrode. Full-field transmission X-ray absorption spectroscopy imaging (FFI-XAS) is employed to probe the charge-compensation mechanism during lithium extraction at the micrometre scale, using two beam configurations with different focal distances (far-focus and near-focus). While the spatially averaged XAS spectra exhibit sluggish reaction, regions exposed to lower dose rates exhibit the expected electrochemical evolution. This contrast enables the identification of a dose threshold for reliable operando measurements. This approach establishes a practical dose limit and provides spatially resolved insight into beam-induced effects, offering both a diagnostic framework and a pathway toward more reliable operando experiments.

cond-mat.mtrl-sci↗

arXiv2026

A large scale multi-modal workflow for battery characterization: from concept to implementation

The development of material acceleration platforms in battery research requires integrating complementary techniques and correlating heterogeneous experimental datasets. Here, this challenge is tackled in a large-scale multimodal program involving fifteen laboratories and facilities across Europe. Coordinated multi-site experiments are performed on state-of-the-art graphite / LiNiO2 Li-ion full cells to address two archetypal scientific questions: is the electrolyte composition impacting electrode properties, and how do electrode materials evolve when cells are cycled to their end-of-life? A fully standardized and centralized workflow is demonstrated, from sample production and delivery, to metadata and data handling, generating seventy-five concatenated datasets shared among all partners. Their integrated analysis shows that scientific conclusions depend critically on both the observable chosen to describe electrode properties, and the measurement technique employed. Individual experiments provide detailed information into specific aspects, such as crystal structures, redox activity, surface processes, morphology, etc., but can also function as binary diagnostic tool. Two-dimensional observable-technique patterns are introduced, in which each pixel encodes a yes, no or uncertain answer to a given scientific question. These patterns serve as multi-property metaviews, e.g. visual genotypes, enabling to classify material behavior and technique suitability according to predefined user demand and criteria, highlighting the interdependencies between measurement choices, extracted parameters and scientific interpretation. This multimodal workflow establishes a proof-of-concept for correlative analysis and underscores challenges toward fully integrated, automated and holistic approaches in energy material science.

physics.app-ph↗

arXiv2020

Edmond Becquerel's colour photographic process involves a Ag/AgCl-based sensitized layer

Edmond Becquerel invented in 1848 the first colour photographic process. The "photochromatic images" he produced raised several questions, among which the photochromic nature of the sensitized layer. Here, we present the first characterization of the sensitized layer created at the surface of a silver plate or a silver foil according to Becquerel's process, which XIX$^{\text{th}}$ century scientists called "silver photochloride". It is constituted by silver nanoparticles dispersed in a micrometric silver chloride grains matrix. It is thus similar to the widely studied Ag/AgCl composites, which suggests new synthesis routes for these photocatalysts. The chemical composition of the sensitized layer has been identified by complementary spectroscopies (EDX, XPS, HAXPES and EXAFS), while its morphology has been studied by electron microscopies (SEM and STEM). These techniques involve X-ray or electron beams, which can have an impact on the silver chloride-based sensitized layer; a large part of this article hence introduces a study of the beam effects and of the way of reducing them.

physics.app-ph↗

arXiv2020

Spectroscopies and electron microscopies unravel the origin of the first colour photographs

The first colours photographs were created by a process introduced by Edmond Becquerel in 1848. The nature of these photochromatic images colours motivated a debate between scientists during the 19th century, which is still not settled. We present the results of chemical analysis (EDX, HAXPES and EXAFS) and morphology studies (SEM, STEM) aiming at explaining the optical properties of the photochromatic images (UV-visible spectroscopy and low loss EELS). We rule out the two hypotheses (pigment and interferences) that have prevailed since 1848, respectively based on variations in the oxidation degree of the compound forming the sensitized layer and periodically spaced photolytic silver planes. A study of the silver nanoparticles dispersions contained in the coloured layers showed specific localizations and size distributions of the nanoparticles for each colour. These results allow us to formulate a plasmonic hypothesis on the origin of the photochromatic images colours.

physics.app-ph↗

arXiv2016

Local motifs in GeS$_2$-Ga$_2$S$_3$ glasses

The structure of (GeS$_2$)$_{0.75}$(Ga$_2$S$_3$)$_{0.25}$ and (GeS$_2$)$_{0.83}$(Ga$_2$S$_3$)$_{0.17}$ glasses was investigated by Raman scattering, high energy X-ray diffraction and extended X-ray absorption fine structure (EXAFS) measurements at the Ga and Ge K-edges. The reverse Monte Carlo simulation technique (RMC) was used to obtain structural models compatible with diffraction and EXAFS datasets. It was found that the coordination number of Ga is close to four. While Ge atoms have only S neighbors, Ga binds to S as well as to Ga atoms showing a violation of chemical ordering in GeS$_2$-Ga$_2$S$_3$ glasses. Analysis of the corner- and edge-sharing between [GeS$_{4/2}$] units revealed that about 30% of germanium atoms participate in the edge-shared tetrahedra.

cond-mat.dis-nn↗