Description du sujet de thèse

Development of light metal hydrides as negative electrode for proton batteries with ionic liquid electrolyte.

Background and objectives
Batteries are the devices of choice for mobility and represent a major lock for energy transition, their continue improvement is demanded by increasing energy storage requirements. Among the families of batteries, nickel-metal hydride (Ni-MH) devices find their main applications in hybrid vehicles, trams and portable tools. These batteries use concentrated KOH as the electrolyte, which makes them competitive in term of safety and low cost. However, this electrolyte limits the choice of materials for this type of battery due to the corrosion it causes , and the energy density through the electrochemical window of water.
Protic ionic liquids provide wider electrochemical window, of the order of 3 to 4 V. Their ionic conductivity over 8 mS.cm-1 at 25°C, thanks to mobile protons, make them interesting candidates as electrolytes in batteries. Finally, their thermal stability above 100°C guarantees the safety of systems .
Previous studies, both in the literature and within the laboratory as part of the ANR H-BAT project (https://anr.fr/Projet-ANR-21-CE50-0030), have demonstrated the proof of concept of using AB5-type hydrides (A: lanthanides; B: transition metals) with a protic ionic liquid electrolyte. However, this intermetallic contains lanthanides, a strategic and critical raw material, and has a limited specific capacity due to their high molar mass. The aim of this thesis will therefore be to develop other families of materials that meet the following criteria: i) lanthanide-free; ii) high specific capacity; iii) capable of electrochemical cycling in a protic ionic liquid medium.
Methodology and tasks of doctoral students
The proposed thesis focuses on the studies of negative electrode part and the electrode-electrolyte interaction. The aim will be to find the alloys with a high specific capacity, which may be impossible to use in KOH medium due to the corrosion, and are able to work as negative electrodes in a protic ionic liquid medium. The work of the thesis will therefore initially consist of developing alloys capable of absorbing hydrogen and characterising them from a structural, physico-chemical and thermodynamic point of view. Their electrochemical behaviour will then be studied in a protic ionic liquid medium: cycling capacity, interactions and ageing.
The tasks of the PhD candidate will be as follows:
- Synthesise light hydride alloys (for example in the TiNi system or in the YB3 (B = Ni, Fe, Mn) system) by metallurgical processing (powder metallurgy, induction melting, etc., depending on the family of alloys)
- Characterise the synthesized alloys from a structural and physico-chemical point of view (XRD, EPMA, SEM, TEM if necessary) and measure their hydrogen sorption properties.
- Test the electrochemical behaviour by galvanostatic cycling measurements, in an electrolyte based on a protic ionic liquid, by optimising the experimental conditions; and in alkaline electrolyte as reference. The ionic liquid electrolytes are being developed by the LRS (Laboratoire de Réactivité de Surface - https://lrs.sorbonne-universite.fr), partners in the ANR H-BAT, and will be synthesised in this laboratory.
- Study the interactions between the ionic liquid and the negative electrode materials showing interesting cycling results (characterisation of the electrode and electrolyte after cycling, study of calendar corrosion of the alloy in storage in the electrolyte without electrochemical cycling, study of hydrogen absorption mechanisms in the material, etc.).
Study the integration of the materials developed into a complete battery prototype by coupling the developed negative electrode, an ionic liquid electrolyte and a positive electrode material developed by the third ANR H-BAT partner, the ICMCB (Institut de Chimie de la Matière Condensée de Bordeaux - https://www.icmcb-bordeaux.cnrs.fr).
Interest in the subject
The aim of the proposed thesis is to establish a new battery concept. It is therefore a major scientific challenge, with the long-term aim of responding to a major challenge facing society: the increasing need for energy storage as part of the energy transition. It is also an opportunity to acquire a wide range of skills: mastery of experimental tools in both materials science and electrochemistry, communication in communities of experts and scientific population, management of a long-term project (the thesis) and finally participation in a collaborative project between several research teams.
Profile required
• 5 years' higher education (engineering degree or Master 2 in research) with a major in materials science (or metallurgy) and an excellent track record. A background in electrochemistry and/or materials for energy (batteries, etc.) would be a plus.
• Like experimental work, curiosity, autonomy, rigour and initiative
• Fluency spoken and written English.

To apply, send a CV, covering letter, transcripts of your Master's and/or engineering school grades and two references (internship or study project supervisors) via the CNRS jobs portal

Contexte de travail

The thesis will be carried out at the Institut de Chimie et des Matériaux Paris-Est (Thiais, https://www.icmpe.cnrs.fr) and is funded as part of the ANR-France 2030 HTASE project (Hydrogen and Advanced Energy Systems Technologies for Sustainable Energy in the Île-De-France region, ANR-23-CMAS-0030).
The ICMPE is a joint research unit (UMR 7182) of the CNRS and the Université Paris-Est Créteil (UPEC). Our laboratory develops original and innovative research in the fields of chemistry and materials science, as well as at the interfaces with physics, engineering and biology, in order to respond to major societal challenges in the cross-disciplinary areas of energy, transport, the environment, sustainable development and health.
Within the M2I (Metallurgy and Inorganic Materials) department, the thesis will be carried out in the HMI (Hydrogen Matter Interaction) group. It will be co-directed by Judith Monnier (Pr UPEC) and Junxian Zhang (IR CNRS) and co-supervised by Valérie Paul-Boncour (DR CNRS).

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

Ce poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST) et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Informations complémentaires

This position is located in a sector covered by the protection of scientific and technical potential (PPST) and therefore requires, in accordance with the regulations, that your arrival be authorized by the competent authority of the MESR.