Maelle MARCHAND-NOWAK PhD defense

Glasses and Ceramics (V&C) team

Abstract
The energy transition and the increasing electrification of transportation are driving a growing demand for safe and high-performance energy storage solutions. Liquid-electrolyte Li-ion batteries, which have dominated the market for the past thirty years, have now reached their limits in terms of energy density and still present safety concerns. All-solid-state batteries with sulfide electrolytes offer a promising alternative, particularly through the emerging concept of diffusion dependent cathodes. These cathodes, composed entirely of active material, minimize the number of interfaces while enhancing energy density. In this context, titanium disulfide (TiS2), the first cathode material used in Li-ion batteries, is regaining interest due to its high electronic conductivity, compatibility with sulfide electrolytes, and excellent lithium diffusion properties. Recent studies have demonstrated that high-energy ball milling of TiS2 can significantly improve its electrochemical performance. This PhD work first investigates the structural and morphological modifications induced by ball milling that lead to such enhancements. It then explores three optimization strategies: partial substitution of sulfur with selenium (TiS2-xSex), the synthesis of anion-rich and potentially amorphous compounds (TiS2+x), and the design of TiS2:FeS2 composite materials. Together, these approaches aim to strengthen the potential of TiS2 as an active material for diffusion dependent cathodes in all-solid- state batteries with sulfide electrolytes.
Jury
Marie Guignard, Chargée de recherche CNRS, ICMCB, Université de Bordeaux / Reporter
Cristel Laberty-Robert, Professeure des Universités, LCMCP, Sorbonne Université / Reporter
Jean-René Duclère, Professeur des Universités, IRCER, Université de Limoges / Examiner
Xavier Rocquefelte, Professeur des Universités, ISCR, Université de Rennes / Examiner
David Le Coq, Professeur des Universités, ISCR, Université de Rennes / PhD Supervisor
Laurent Calvez, Professeur des Universités, Université de Rennes / PhD Co-Supervisor

Contacts
Laurent Calvez, laurent.calvez@univ-rennes.fr
Maelle Marchand-Nowak, maelle.marchand-nowak@univ-rennes.fr