Though my research work, I explore different problems with a focus on multi-scale and multi-physics modeling with the intention of developing an accurate theoretical understanding of the phenomena at hand.
Chemo-mechanical couplings in batteries. In this work, I collaborate with electrochemists from the Condensed Matter Physics (PMC) lab of Ecole polytechique in a combined experimental/theoretical project aiming at understanding the effect of mechanical stress on the diffusion of lithium in silicon. This question finds applications in the development of new negative electrode materials for lithium-ion batteries such as silicon or methylated silicon. Historically, the question of the contribution of mechanical stresses to a species diffusion in a solid has been addressed on thermodynamic grounds and in the setting of elasticity in the seminal work of Larché & Cahn "A linear theory of thermochemical equilibrium of solids under stress". Here, we aim at characterizing quantitatively this effect in the setting of lithium diffusion in silicon, which involves irreversible elasto-visco-plastic deformation and therefore requires a more sophisticated modeling.
The understanding of the behavior of ferroelectric ceramics require both a multi-scale approach and a proper modeling of the electro-mechanical couplings. To investigate the phenomenon of ferroelectric switching, I currently develop with D. Kochmann at ETH Zurich a mesoscale model that accounts for the kinetics of the evolution of microstructure happening in ferroelectrics at the micrometer scale. Experiments of polarization reversal at different rates help us capturing the essential kinetics features missing from current mesoscale models.
The fracture of polycrystalline graphene is an example of a purely mechanical problem at the microscale which ultimately lies on the atomic structure. I investigate that phenomenon through atomic-scale simulations as part of a multi-scale model of indentation experiments on graphene sheets.
The electric properties of semiconductors are coupled in a non-trivial fashion to their mechanical deformation, which plays a role in, among others, deformable solar cells. From the theoretical perspective, I explore these couplings through a modeling based on thermodynamics (energy and entropy being ultimately where the different physics meet). Experimental measurements of the electric response of solar cells under mechanical loading confirmed the significance of that coupling.
Morphological instabilities observed on crystal surfaces is another phenomenon that involves simultaneously elasticity, diffusion of chemical species and electrostatics. By means of stability analysis of the phenomenon of crystal growth, I question the fundamental mechanism responsible for the appearance of complex surface morphologies.