Effet des hétérogénéités de contraintes mécaniques appliquées sur une batterie Li-ion sur le vieillissement et la sécurité

The Li-ion battery is the technology shared by all automakers to provide the energy storage required for the deployment of electrified vehicles. During its life cycle, a battery may encounter a wide range of operating conditions. Certain operating conditions can accelerate battery degradation, leading to an accelerated loss of capacity and potentially to safety problems. One of these operating conditions is linked to the preparation of the battery pack itself, which mechanically constrains the battery.
During battery operation, successive phases of lithiation/delithiation of battery materials cause changes in thickness during cycling. This is known as battery swelling. This phenomenon is actually a combination of mechanical, electrochemical and thermal phenomena. These changes in thickness can lead to irreversible thickness heterogeneities on the surface of the negative electrode, subsequently leading to stress heterogeneities during cycling.
The aim of the proposed PhD work is to use an experimental and modeling approach to address the effect of heterogeneous mechanical stresses applied to a Li-ion battery during operation, and their consequences on battery aging and safety.

This thesis topic is in line with the work undertaken within IFPEN and Stellantis on this theme, and will benefit from multiphysics skills, previous experience and tools developed in both structures. In fact, the PhD student will be able to draw on recent theses on ageing and safety issues, as well as recent work combining electrochemistry and thermomechanics.