Compatibility between solid state polymer electrolytes and high voltage cathode materials in lithium-ion batteries, characterization and interface engineering

In a context of a technological shift towards electric mobility, the main current technological solution is the lithium-ion battery. However, state of the art lithium-ion batteries still lack a sufficient energy density to compete with the internal combustion engine on autonomy. Lithium-ion batteries also pose a serious safety risk due to the phenomenon of thermal runaway that limits their acceptance by the market.
Today, IFPEN is researching solutions to increase the energy density and the safety of lithium-ion batteries, the most promising solution are the solid-state electrolytes to replace the currently used liquid ones. Thus, a solid-state electrolyte based on a crosslinked polymer network has been developed by IFPEN, this electrolyte has been tested in full cells. However, the material in its current state is not compatible with high voltage cathode materials like nickel-manganese-cobalt oxides (NMC), the source of the problem has been narrowed to the formation of a passivating layer on the cathode during the first charge.
The aim of this PhD project is first to study the formation of this passivating layer and determine both its chemical structure and its formation mechanism. This will be done by combining electrochemical techniques and micro scale characterization techniques (TEM, XPS, …) to observe the passivation layer. Once this information has been acquired, solutions will be proposed and tested to prevent its formation (innovative coatings, additives, …). The final aim of the project being the manufacturing of full cells with a high voltage cathode and the crosslinked polymer electrolyte in mono-layer pouch cells.

Keywords: Lithiu-ion batteries, polymer electrolytes, electron microscopy, electrochemistry

• Academic supervisor    Dr. Virgile ROUCHON, IFPEN, ORCID : 0000-0001-8520-1378
• Doctoral School    ED206, école doctorale de chimie de l’université de Lyon
• IFPEN supervisor    Dr. Niki HALTTUNEN, ORCID : 0000-0002-1625-3753
• PhD location    IFPEN, Solaize, France
• Duration and start date    3 years, starting in the fourth quarter 2024 (Novembre 4th)
• Employer    IFPEN
• Academic requirements    University Master degree in  Chemistry of inorganic and polymer materials, analytical sciences, electrochemistry 
• Language requirements    English level B2 (CEFR)     

To apply, please send your cover letter and CV to the IFPEN supervisor indicated below.