Beyond Conventional Synchrotron-based X-ray Spectroscopy: Fundamental Insights and Application to Positive Electrodes for Metal-ion Batteries
Jazer Jose TOGONON
(Ligne CRISTAL, Synchrotron SOLEIL & Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Université de Bordeaux)
Lundi 25 novembre 2024 – 14h00
ICMCB Amphitheatre, 87 Avenue du Dr Albert Schweitzer, 33600 Pessac
Visio : https://u-bordeaux-fr.zoom.us/j/81829884909?pwd=MW2lVANV5vQs5GDE9LyTOjFnKB9jfQ.1
The design of positive electrode materials for metal-ion batteries has been driven towards the goal of having enhanced safety and achieving high capacity and energy density. These targets mainly rely on the capacity of the electrode material to exchange Li+ ions (or Na+ and K+ ions) quickly and reversibly while operational at larger potential windows. The control of the composition and stoichiometry, as well as the crystal structure, of these electrode materials is a crucial point in design to manifest improved electrochemical properties and higher structural stability. Hence, a holistic understanding of the structure and property relationship is essential.
Various positive electrode materials, including polyanionic compounds and layered transition metal oxides, are investigated using novel characterization techniques utilizing synchrotron radiation sources. This study presents a comprehensive approach to explain the structure-property relationships of the materials by combining structural analysis through X-ray diffraction measurements with hard X-ray spectroscopy studies. Mainly, the project explores the electronic structure of various battery chemistries using beyond conventional X-ray spectroscopic techniques like, high-energy resolution fluorescence-detected X-ray absorption near-edge structure (HERFD-XANES) spectroscopy, non-resonant X-ray emission spectroscopy (XES), and X-ray Raman scattering (XRS).
Specifically, the geometric and electronic distinctions between Tavorite-type LiVPO4F and KTP-type KVPO4F are analyzed using HERFD-XANES and XES. Additionally, the ligand and electronic environment in the mixed polyanionic compound KVPO4F1-xOx (x = 0, 0.25, 0.5, 0.75, 1) are investigated using valence-to-core XES. Meanwhile, a combination of hard X-ray spectroscopy techniques is employed to probe the strong covalent nature of Ni-O bonds in layered LiNiO2. Finally, both ex situ and operando X-ray spectroscopy measurements are used to examine the cationic and anionic redox present in Li/Mn-rich layered oxides.
Overall, the application of multiple synchrotron-based X-ray spectroscopy techniques is intended broadly to improve fundamental material understanding and future development strategies.
Jury members :
Mme LYONNARD Sandrine - Directrice de recherche, CNRS-CEA-IRIG - Rapporteure
M. ARČON Iztok - Professor, University of Nova Gorica - Rapporteur
M. STIEVANO Lorenzo - Professeur, Université de Montpellier - Examinateur
M. AYMONIER Cyril - Directeur de recherche, CNRS-ICMCB - Examinateur
M. LONGO Alessandro - Senior Researcher, ISMN-CNR, OUS Palermo - Examinateur
Mme CROGUENNEC - Laurence Directrice de recherche, CNRS-ICMCB - Directrice
Mme IADECOLA Antonella - Ingénieure de recherche, HDR, CNRS-PHENIX - Co-directrice
M. CHOTARD Jean-Noël - Maître de conférences, LRCS-UPJV - Co-encadrant