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 elasticty in the seminal work of Larché & Cahn "A linear theory of thermochemical equilibrium of solids under stress". Here, we aim at characterizing quantititatively 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 a mesoscale model that account 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.