DRF : Sujet de thèse SL-DRF-17-0512
Etude par des techniques de diffusion in-situ et operando des mécanismes de vieillissement dans les batteries Lithium-ion à base de Silicium
Silicon, due to its great capacity (3576 mAh/g), is one of the best candidates to substitute graphite in the new generation of Lithium-ion batteries. Yet, Silicon anodes present large volume expansion during the lithiation which induces a large irreversible capacity. Silicon based nanostructured materials (nanoparticles, nanowires, nanocomposites) attract considerable attention because they can mitigate volume expansion effects, increase the surface area and allow innovative architectures. Understanding the basic mechanisms of lithiation and delithiation in these materials is critical to improve the performance and lifetime of Li-ion batteries. Although post-mortem investigations at various states of (dis)charges are invaluable, there is a growing interest in operando methods to continuously diagnose the battery components in the course of device cycling.
In this subject, we propose a combination of cutting-edge in-situ and operando scattering techniques to address the problematic of ageing in Lithium-ion batteries with nanoSilicon-based electrodes more particularly focusing on critical processes such as Solid Electrolyte Interphase (SEI) formation, structural deformations and size variations of the nano-objects. X-rays reflectivity, X-rays diffraction, Small Angle Neutron and X-rays scattering are ideal tools to probe the electrode-electrolyte interface, the size, shape, organization and internal structure of Si nano-objects. These techniques will be coupled with electrochemical characterizations, with the aim of providing a detailed understanding of complex mechanisms occurring during the charge and the discharge of the Lithium battery, which are critical for improving the performances of these energy storage devices.
Modélisation et Exploration des Matériaux
Groupe Service Général de Rayons X
Centre : Grenoble
Date souhaitée pour le début de la thèse : 01/10/2017
Ecole Doctorale de Physique de Grenoble