PH'D defense Mme Delphine Yetim

Mme Delphine Yetim will present her thesis "Development of an innovative process for the closed-loop valorization of used cathode materials from lithium-ion batteries battery".
Abstract : Identifying the technologies available on the market, developing more ecological hydrometallurgical processes, reusing recycled battery materials in a closed loop... The problems and challenges raised by the recycling of lithium-ion batteries are numerous and represent today a crucial issue for the energy transition. This thesis aimed to proposing an innovative process of recovery and reuse in closed loop of used cathode materials from the drone activity. To build this solution, a rigorous analysis protocol to identify and study a large and representative panel of batteries present on the drone market have been develop. Then, it was chosen to use innovative organic solvents, called "deep eutectic solvent", to recover by hydrometallurgy the critical metals (cobalt and lithium) contained in the cathode materials. However, little information on the dissolution mechanisms of used cathode materials in DES medium is provided in the literature. A first study has been therefore carried out, by UV-visible spectroscopy, on the interactions between metal salts and DES solvents, and allowed to better understanding the reaction mechanisms. Leaching tests have been carried out using both model materials (LCO and NMC) and real used cathode materials (Al current collector covered with LCO active material). Several DES have been tested, but the ethylene glycol – choline chlorine mixture has been selected. In order to enhance the dissolution kinetics, a small proportion of HCl has been added to the system. The leaching protocol have been optimized using the Design of Experiments methodology. At the optimum conditions: ChCl: EG (1:2) with 0.8 mol.L-1 of HCl, with a ratio(wt.) S/L of 1/50, heated to 87.5 °C, for 2 h. After being completely dissolved, the metals have been then recovered from the DES by precipitation, calcined and reused as active materials of button cells batteries prepared in the laboratory. Using this method, the DES solvent has been recovered and reused in a closed loop without suffering any damage. Furthermore, this work has also shown that the recovered battery materials can be reused into the battery manufacturing cycle without changing their electrochemical performance. Indeed, this process allowed to obtain a homogeneous powder with a morphology similar to the initial materials (particle size <1 μm), presenting good capacities in cycling (154 mAh.g-1).

Thesis Supervisors : Jean-Claude LEPRETRE, Lenka SVECOVA

Jury composition :
Jean-Claude LEPRETRE PROFESSEUR DES UNIVERSITES Université Grenoble Alpes Directeur de thèse
Marie LEPAGE MOSTEFA MAITRE DE CONFERENCE Université de Lorraine Examinateur
Corine  BAS PROFESSEUR DES UNIVERSITES Université Savoie Mont Blanc Examinateur
Alexandre CHAGNES PROFESSEUR DES UNIVERSITES Université de Lorraine Rapporteur
François TRAN VAN PROFESSEUR DES UNIVERSITES Université de Tours Rapporteur


Date infos
Thesis Defense : January 26, 2022 at 9h30
Address of the thesis defense : Amphi MJK