Description du sujet de thèse

Though aqueous Zn/air batteries are promising (low storage cost, high recyclability, high energy density, safety), their technological maturity remains low. Current systems suffer from a low energy density, a low power density and a low energy efficiency. These issues are related to the sluggish kinetics of oxygen evolution (charge reaction - OER) and reduction reactions (discharge reaction – ORR) involved at the positive electrode. Designing a stable and truly reversible air electrode could revolutionize electrical performances and cyclability of these systems. The commonly used research strategy consists in designing ever more efficient materials. Nevertheless, it has been recently demonstrated that beyond this classical approach, applying a magnetic field can strongly improve reactions kinetics. This is the reason why, during the PhD project the focus will be on understanding the effects induced by the interaction between the magnetic field and the catalytic material. These will be correlated with the magnetic properties of the materials. Particular attention will also be paid to the study of changes in the mass transfer within the electrolyte under a magnetic field. The catalysts studied will be mainly synthesized by a partner laboratory (Institut de Chimie de la Matière Condensée de Bordeaux - ICMCB). These original composite materials will consist of an active phase (sulfide or oxide) composed of 3d transition metals and supported on a two-dimensional material of the MXene type.

Contexte de travail

The work will be carried out as part of the ANR MAFIA project at the Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), an internationally recognized laboratory in electrocatalysis and materials science.
In this thesis, the candidate will be required to:
- Perform a literature review on the subject. A bibliographic report must be completed and submitted at the end of the first year of the thesis.
- Contribute to the development of electrochemical cells used to study the effect of a magnetic field on the kinetics of OER and ORR.
- Assess the activity and stability of materials using electrochemical techniques such as cyclic voltammetry, chronopotentiometry, or electrochemical impedance spectroscopy.
- Perform in situ vibrational spectroscopy studies (Raman and FTIR) to evaluate the dynamics of the electrode/electrolyte interface under operating conditions.
- Develop a new methodology combining different characterization techniques (XPS, DRX, SEM, in situ MET, etc.) and allowing the characterization of surface reconstruction and degradation phenomena affecting catalytic materials (active phase and support) under operating conditions.

Contraintes et risques

Standard chemical hazard