Description du sujet de thèse

All-solid-state lithium batteries offer enhanced safety and energy density. Solid electrolytes, such as argyrodites, can achieve high lithium-ion conductivities through controlled chemical substitutions. Understanding their disordered local structure is essential. Solid-state NMR, combined with DFT, enables probing of such structural disorder and Li⁺ dynamics. This project first aims to accurately assign the ³¹P and ⁷Li NMR signals in substituted argyrodites (Li₆₋ₓPS₅₋ₓBrXₓ, X = Cl, I), by combining experimental spectroscopy with ab initio calculations (VASP, CASTEP), supported by machine learning potentials to efficiently model structural disorder. Particular attention will be given to identifying structures that promote ionic conductivity. The second part of the project focuses on ion dynamics at interfaces between electrolytes and electrodes (argyrodite/LNMO, argyrodite/halide, halide/LNMO), studied using 2D NMR (EXSY) and isotopic labeling. These experimental investigations will be complemented by advanced modeling of interfacial ion transport, using molecular dynamics simulations based on machine-learning interatomic potentials. This integrated approach will help elucidate the key mechanisms driving the performance of all-solid-state batteries.

Contexte de travail

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Created in 1995, the Bordeaux Institute of Condensed Matter Chemistry (ICMCB) focuses its research on Solid State Chemistry, Materials Science and Process Chemistry: designing, preparing, shaping and characterizing materials to discover, control and optimize specific functions. The ICMCB carries out fundamental research on model materials and/or materials with potential applications.
The ICMCB is a UMR with an average staff of 280 (permanent and non-permanent), with 3 tutelles, hosted by the CNRS and in total ZRR.
The position is located in a sector covered by the protection of scientific and technical potential (PPST), and therefore requires, in accordance with regulations, that the arrival of the agent be authorized by the competent authority of the MESR.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

CEMHTI and ICMCB, both active members of the RS2E network, combine their complementary expertise in synthesis, characterization, and modeling of materials for all-solid-state batteries. CEMHTI is a leading laboratory in advanced solid-state NMR, particularly applied to battery materials, with Elodie Salager, an expert in NMR and ion dynamics, leading since 2023 the characterization part of the LIMASSE project focused on solid electrolytes. ICMCB is internationally recognized for its work on electrode materials and the development of innovative experimental approaches, such as NMR spectroscopy combined with DFT calculations, led by Dany Carlier. The recent arrival of Aurélie Champagne, a CNRS researcher specializing in ab initio calculations of complex systems, strengthens the laboratory's expertise in modeling. Her research aims to understand and model ionic transport mechanisms in solids and interfaces to guide the discovery and optimization of new materials. The PhD project includes significant experimental work and analysis within both laboratories, ensuring strong synergy between experimental studies and theoretical modeling.