Understanding and Optimizing of Electrophoretic Deposition Process in Pulsed Mode in Aqueous Medium of Model Nanoparticles and of Nanomaterials of Industrial Interest ; Compréhension et Optimisation du Procédé de Dépôt par Électrophorèse en Mode Pulsé en Milieu Aqueux de Nanoparticules Modèles et d'Intérêt Industriel

This thesis work is part of an industrial issue aiming to achieve micrometer-thick deposits of lithium battery electrode materials by electrophoretic deposition. Due to constraints related to the large-scale use of organic solvent suspensions of ceramic materials, the EPD (ElectroPhoretic Deposition) process considered in the context of this work involves colloidal suspensions of nanoparticles in an aqueous medium, as well as pulsed polarization to limit the harmful water electrolysis phenomenon in obtaining dense deposits.The objective of this study is to optimize the EPD process in terms of deposition yield and quality, using model suspensions of silica nanoparticles. Thus, the synthesis conditions of these particles obtained by the Stöber approach, were optimized to get geometric and physico-chemical characteristics (zeta potential, isoelectric point) very similar to the industrial materials of interest.The deposition kinetics by EPD were simulated through a first finite element model and compared to experimental data on both monodisperse silica nanoparticle suspensions and polydisperse suspensions of industrial electrode materials.A second electrochemical model allowed simulating the evolution of pH at the electrode surface in pulsed mode and providing a better understanding of the process. The hypothesis of an extended mechanism of the DLVO theory including a decrease in pH resulting from water oxidation was highlighted in the low-frequency range of the pulsed regime. Furthermore, it was shown that this acidification can be limited by decreasing the duty cycle, thus increasing the relaxation period of the potential in pulsed mode, and operating at high frequencies (f > 1000 Hz).Finally, particular attention was focused on the cracking of deposits that occurs during the drying stage. The use of polydisperse model suspensions or drying conditions at high relative humidity improved the quality of the deposits without eliminating the cracks. However, incorporating an anionic polyelectrolyte (xanthan gum) ...