The proposed PhD thesis focuses on the development of innovative polymer electrolytes for next-generation batteries, aimed at improving the safety and performance of energy storage systems.

Polymer electrolytes represent a promising solution to replace traditional liquid electrolytes. However, their development is limited by challenges related to ionic conductivity and low ion transport numbers. The addition of Deep Eutectic Solvents (DES) into the polymer matrix enhances ionic conductivity. Furthermore, the "single-ion" approach, based on grafting the counter-ion onto the polymer chain, leads to unipolar conduction.

CEA has recently developed "single-ion eutectogel" electrolytes, obtained by polymerizing a DES composed of a single-ion monomer and a hydrogen bond donor (HBD). These electrolytes exhibit very promising performance, achieving unipolar ionic conductivities greater than 0.1 mS/cm at room temperature. However, it is essential to further explore the relationships between formulation, structure, and properties, as well as the conduction mechanisms within these materials, in order to continue their development.

The thesis will be structured in three main phases:

Study of the reference system: Establish a research methodology to link polymerizable formulations, polymer structure, and their electrochemical properties. This will include the study of the starting DES and the electrolyte resulting from its polymerization. The study of conduction mechanisms within these electrolytes will be a central focus of this phase.

Optimization of properties: Based on the results from the previous phase, optimize the properties of the electrolytes through formulation work to select the most promising electrolyte for the next phase.

Integration into a complete system: Explore the integration of the electrolyte into a battery cell, using the in situ polymerization process to synthesize the electrolyte directly within the cell.

Physicochemical techniques (NMR, DSC, TGA, FTIR, RAMAN, SEC, SAXS, ...) and electrochemical techniques (EIS, CV, GCPL, ...) will be used throughout the project.

The PhD will be carried out in collaboration with CEA and LEPMI, providing access to state-of-the-art infrastructures and recognized expertise in formulation, polymer chemistry, and polymer electrolyte electrochemistry.