Molecular characterization and imaging of the solid electrolyte interphase from high resolution mass spectrometry

Scientific context: A fully funded PhD position is available for candidates with a strong background in chemistry, physics, or materials science. The successful candidate will join the IPREM institute (https://iprem.univ-pau.fr/) at the University of Pau and Pays de l'Adour (UPPA). The current offer lies in the context of the REACTIF joint research program between IPREM, the iC2MC joint laboratory, and Saft (https://saft.com/), a pioneering company specializing in innovative electrochemical storage devices.

The REACTIF project, Deciphering REACtion Mechanisms at Electrode/Electrolyte Interfaces: a Key Step toward High-PerFormance Lithium-Ion Batteries, focuses on developing advanced and transdisciplinary methods integrating analytical chemistry, computer simulations, and chemical-physics surface characterizations to investigate and improve the performance and durability of lithium-ion batteries (LIBs). A key challenge in LIB technology is the formation and evolution of interfacial layers along battery charge and discharge operations. More precisely, the Solid Electrolyte Interphase (SEI) at the anode and the Cathode Electrolyte Interphase (CEI) at the cathode. These nanometric layers, formed during electrochemical cycling, play a crucial role in battery stability but are also central to aging phenomena and performance loss. Within the REACTIF project, this PhD work will focus on deciphering at the molecular level the chemical processes that govern the formation and composition of SEI and CEI.

Description of the research project: This PhD offer focuses on the instrumental and methodological development required to couple high-resolution mass spectrometry (HRMS) techniques such as FT-ICR-MS with surface-sensitive techniques including ToF-SIMS, XPS, and AES for the analysis of complex interfaces in lithium-ion batteries.

The candidate will first work on model battery samples previously studied in the lab, with the goal of later extending the methods to more advanced materials. The IPREM laboratory has strong expertise in coupling surface techniques (ToF-SIMS, XPS, AES) for spatially resolved chemical imaging. The integration of FT-ICR-MS will significantly enhance molecular resolution and analytical accuracy, particularly for the identification of organic/inorganic species involved in interfacial degradation mechanisms.

Initial work will involve the development of experimental protocols. The project will then focus on establishing cross-calibration methods between ToF-SIMS and FT-ICR-MS data, leveraging the high mass resolution of FT-ICR to refine ToF-SIMS peak assignments. An in-house software tool will assist with spectral alignment and mass recalibration. Combined interpretation with XPS and AES will integrate previous knowledge and validate chemical assignments. The combination of complementary spatial resolutions, from nanometer-scale with ToF-SIMS and AES to micrometer-scale with MALDI-FT-ICR-MS, will enable a multi-scale mapping of organic/inorganic species.

The candidate will also be in charge of selecting the systems of interest (i.e., electrode and electrolyte compositions), preparing lab Li-ion cells, conducting electrical tests (cycling, performance analysis), and disassembling cells for post-mortem analyses. These tasks will be performed at Saft, Bordeaux. The final objective will be to understand the impact of the electrode and electrolyte compositions on the system's performance, which is directly correlated with the SEI and CEI compositions.

L’IPREM  est une Unité Mixte de Recherche CNRS / UPPA (UMR 5254).

L'IPREM regroupe plus de 300 personnes qui s’intéressent au développement de connaissances fondamentales en physico-chimie, chimie analytique et microbiologie, en relation avec des applications concernant la structure du vivant, la gestion de l’environnement et les propriétés fonctionnelles de différentes classes de matériaux.

Candidate profile: The successful candidate should old a Master degree (Maste 2 in France) or equivalent in Chemistry, Analytical Chemistry, material sciences or Chemical-Physics. S/he should be particularly motivated to work in an environment with national and international collaborations, in contact with industrial partners and at the interface of several disciplines. English speaking is required. A previous experience in surface characterization and/or mass spectrometry would be appreciated.