Description du sujet de thèse

Redox flow battery (RFB) is considered as a low-cost alternative for stationary energy storage, which is essential for keeping the green energy (e.g. wind, solar) that have intermittent nature. The energy storage in RFB is achieved by changing the redox state of the electrolytes in the tanks, which is governed by electrochemical reactions. To increase the current density for charging/discharging of RFB, three strategies are spotted: (1) Increase the charge transfer kinetics on the electrode. This depends on the chosen electrolyte and electrode material. (2) Increase the active surface area of the electrode. This is usually achieved by using porous electrodes such as carbon felt. (3) Improve the mass transport of electrolyte by flow management. This is a key issue in RFB. On one hand, the flow may accelerate the mass transport of the electrolyte to increase the current density of charging/discharging, but on the other hand the flow is also intrinsically a source of loss of energy. The high pressure in the flow may also induce technical challenges, such as the leakage of electrolyte. It should be noted that (2) and (3) are sensitively dependent on the geometry of the electrode, which clearly sees high importance in the battery design.
This PhD work will target at optimizing the performance of redox flow batteries by managing the above-mentioned aspects. It will be intensively based on numerical simulations of the electrochemistry and the flow. The general workflow would be: design of electrode geometry - Simulation of flow by CFD - Simulate electrochemical processes with charge transfer kinetics, and mass transport from the flow - Experimental validation of simulation results (in close collaboration with experimentalists). Eventually, heat management will also be considered. Moreover, risk analysis based on the heterogeneity of the battery will be explored for the evaluation of the durability of the batteries.
Requirement for candidate:
Solid background in engineering, especially on the finite element method for solving partial differential equations.
Good knowledge in electrochemistry and fluid dynamics.
Oral and written communication in English.
Experiences in using COMSOL is a bonus.

Contexte de travail

This work is supported by PEPR Project “Radical approach for achieving high stability aqueous organic redox flow batteries” (RADICAL), which aims at developing aqueous organic redox flow batteries without critical resources and stable for long-term. The Ph.D. student will be co-supervised by CNRS researcher Dr. Liang Liu from Laboratoire de Chimie Physique et Microbiologie pour les Matériaux et l'Environnement (LCPME), and Prof. Sophie Didierjean from Laboratoire Energies & Mécaniques Théorique et Appliquée (LEMTA). Dr. Liang Liu is interested in spatially localized electrochemistry. The research activities are on the development of instrumentation, experimental methodology and physical model-based quantitative analysis. Prof. Sophie Didierjean is expert on electrochemical engineering of fuel cells, electrolyzers and redox flow batteries. Both laboratoires are located in Nancy. The Ph.D. student will register in Université de Lorraine, France.

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Contraintes et risques

No particular risk identified.