Description du sujet de thèse

Context: To maximize the performance and lifespan of batteries, it is crucial to understand and monitor the mechanisms governing their operation throughout their lifecycle. Particularly, the transport phenomena of Li(Na) ions in the electrolyte cause heterogeneities in the intercalation rates of the electrodes, leading to polarization phenomena and a reduction in capacity. Furthermore, they can also lead to the electrodeposition of metallic lithium on the surface of the negative electrode, thus posing risks of short circuits. Consequently, the concentration gradients of ions in the electrodes and the electrolyte (orientated across the plane, as illustrated in the figure) have been extensively studied using various techniques such as radiography, Raman spectroscopy, and NMR spectroscopy. However, it is only recently that researchers have begun to study the motion of the electrolyte and its impact on lithium concentration in the planar direction (see Figure). In particular, Solchenbach et al., using pore volume calculations and moment of inertia measurements, were able to observe the movement of the electrolyte and concentration gradients in a commercial cylindrical battery[1]. This previously unidentified phenomenon, called "electrolyte motion induced salt inhomogeneity" (EMSI), has been directly correlated with battery degradation. Although this study has highlighted this new degradation phenomenon, it is limited by the absence of real-time and real-condition (operando) experimental data, necessary to evaluate the dynamic aspect of ion transport. In this context, the CSE laboratory has been using optical fiber sensors for several years to monitor various physical and chemical parameters in batteries[2]. For example, tilted fiber Bragg grating (TFBG) sensors have been used to monitor the kinetics of mass transport and the growth of lithium dendrites at lithium anode interfaces[3]. Additionally, evanescent wave infrared spectroscopy (IR-FEWS) has been employed to observe lithium concentration gradients and desolvation processes across different cell models[4].

Objective: Building on these preliminary research efforts, the thesis aims to exploit the combined capabilities of these optical fiber spectroscopic techniques to explore the dynamics of the electrolyte across and within the plane orientation of the cell. By applying these optical techniques, we will explore the impact of various parameters that might influence the movement of the electrolyte and ions, as well as their effect on battery performance. The charging and discharging regimes of the cell, the volume of electrolyte, and the proportion of silicon in the anode will be studied. 3D visualizations by synchrotron X-ray tomography will also be performed, to observe the volume changes at the electrode level that induce electrolyte movement.

Candidate profile: Degree in engineering or a master's in physics or chemistry. The candidate must have a strong aptitude for experimentation and be capable of adapting to problems from different fields. Proficiency in English and programming skills in Python are required.


[1] S. Solchenbach, C. Tacconis, A.G. Martin, V. Peters, L. Wallisch, A. Stanke, J. Hofer, D. Renz, B. Lewerich, G. Bauer, M. Wichmann, D. Goldbach, A. Adam, M. Spielbauer, P. Lamp, J. Wandt, Electrolyte motion induced salt inhomogeneity – a novel aging mechanism in large-format lithium-ion cells, Energy Environ. Sci. 17 (2024) 7294–7317.

[2] J. Huang, L. Albero Blanquer, J. Bonefacino, E.R. Logan, D. Alves Dalla Corte, C. Delacourt, B.M. Gallant, S.T. Boles, J.R. Dahn, H.-Y. Tam, J.-M. Tarascon, Operando decoding of chemical and thermal events in commercial Na(Li)-ion cells via optical sensors, Nat. Energy 5 (2020) 674–683.

[3] X. Han, H. Zhong, K. Li, X. Xue, W. Wu, N. Hu, X. Lu, J. Huang, G. Xiao, Y. Mai, T. Guo, Operando monitoring of dendrite formation in lithium metal batteries via ultrasensitive tilted fiber Bragg grating sensors, Light Sci. Appl. 13 (2024) 24.

[4] C. Gervillié-Mouravieff, C. Boussard-Plédel, J. Huang, C. Leau, L.A. Blanquer, M.B. Yahia, M.-L. Doublet, S.T. Boles, X.H. Zhang, J.L. Adam, J.-M. Tarascon, Unlocking cell chemistry evolution with operando fibre optic infrared spectroscopy in commercial Na(Li)-ion batteries, Nat. Energy 7 (2022) 1157–1169.

Contexte de travail

The CSE lab is a renowned expert in the field of batteries, with its major achievements including the search for new Li reactivity mechanisms, the mastery of interfaces, the assembly of cells, and the exploration of chemistries beyond Li-ion such as Na-ion and all-solid-state batteries. The laboratory is also pioneer in integrating optical fibers into batteries for monitoring physicochemical processes under real conditions.

The doctoral work is part of the SENSIGA project, which is part of the Battery2030 initiative.

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.