Mlle Juliette Charbonnel Defense

Abstract : Today, all-solid-state battery technology arouses à great enthusiasm, because it represents one of the credible way to cross the barrier of 400Wh/kg. By improving the safety, this technology allows to integrate Li metal and the most energetic cathode materials. Commonly mentioned arguments are:
As the electrolyte is solid, there is not SEI and without SEI there is not reaction to initiate the thermal runaway
Solid electrolyte can be considered as thermally inert, which decreases considerably the reaction energy of the battery.
To be efficient, solid electrolyte must be very little porous, which eliminates passageways of the dendrites during fast charge. To be efficient, solid electrolyte must be very little porous, which cancelled passageways of the dendrites since fast charge.
Unfortunately these arguments are mainly hypothesis low verified. Moreover, although very attractive, all-solid-state battery technology poses important technical issues, as implementation of very low porous electrolyte and very fine (5 to 20 µm). Furthermore, it exists a lot 7of solid electrolyte famillies as polymer conductors, oxides or sulfide. Thereby, it is hard to identify already the winning material, especially since to estimate the safety of a solution, it is currently necessary to test cells with représentative dimesions as 18650. Thus, the goal of this PhD will be to determine the level of safety of new battery technology by estimating the potential of each material and to compare them with technologies more classical.
It has been demonstrated that thermal runaway energy is egal to the sum of energies of chimical and electrochemical reactions contained in the cell. By leaning on this methodology, the thesis will identify the security potential of new all-solid-state battery technologies. For that, from a methodology point of view, characterizations as DSC, TGA-MS and calorimetry will enforce to identify the reactivity of materials of a cell and their interactions. From these values and from models developed in-house by the CEA, the PhD will propose a change of scale to predict the kinetic reaction and thus to to predict the security potential of a technology before to manufacture a reel cell, which will allow to bring elements to the emergence of a new technology.
Ultimately, the PhD will propose a methodology allowing to assess new materials for all Li-ion battery technologies such as, for example, gel technologies or new coating of active materials.