PhD position H/F "Operando investigation of chemo-mechanical degradation in sulfide-based solid...

In a joint ANR project between LEPMI (CNRS), CEA-IRIG and ILL in Grenoble, we are looking for a PhD student to work on the characterisation of solid-state batteries using thiosulfates solid electrolyte and to improve the electrochemical performance of the system studied. Understanding the reactivity of the solid electrolyte (sulphide based) and the Li-ion transport properties in the electrochemical cell by means of advanced characterisation techniques at laboratory scale and large-scale facilities will help to design better solid-state batteries. Several techniques such as impedance spectroscopy coupled to dilatometric measurement and acoustic emission are planned to improve the knowledge about bulk/interfacial phenomena, whereas operando neutron diffraction should help addressing the bulk stability. The applicant should hold a master degree or engineering degree in Material Science, Chemistry, Physics or related field. Knowledge in electrochemistry and batteries is required and knowledge on solid state batteries would be an asset. We are offering 3 years contract obtained from an ANR project “OpInSolid”. The PhD student will work on close collaboration with a postdoc also hired for this project.

Since the commercialization of the first Li-ion battery in the early 90s', drastic progresses have been made in improving the energy density and power density of the batteries. Unfortunately, and despite all the efforts made to improve the Li-ion batteries, this technology starts to reach its limitations owing to several factors like i) the recent concerns about the availability of Li, ii) the issues regarding safety and finally, iii) the difficulty to replace the Li host negative electrode by Li metal. One alternative for making safer and high energetic batteries is to substitute the flammable organic- based liquid electrolyte with a solid one and to replace the Li host material by Li metal. Several families of solid electrolytes (SE) are reported in the literature, among them oxides, thiophosphates, polymers, sulfides and many others. Based on their ease of synthesis/manufacturing, we investigate sulfide-based solid electrolytes and propose to thoroughly characterize them in an operando multiscale approach using laboratory experiment and large-scale facilities. To date, no commercially viable solution has been realized because of the multiple drawbacks suffered by these materials, mostly related to chemo-mechanical degradation and interfacial issues. Indeed, in solid-state batteries, the very narrow potential window (less than 1 V) coupled to multiple interfaces, generate a lot of local chemical degradations. Mechanical degradation may arise from i) the sintering process and ii) the “breathing” of the electrode materials during cycling. Finally, the intrinsic instability between the cathode materials (made of lithiated oxides) and the sulfides-based solid electrolyte leads to enhanced chemical decomposition generating insulating products and mechanical issues.The combination of those chemo-mechanical degradations makes the solid-state batteries based on sulfide solid electrolytes an engineering challenge to improve and stabilize the electrochemical performance for a future commercialization.