The Postdoctoral position will be part of the PEPR Battery Hipohybat project. This project aims to develop high-power Na-ion batteries in close collaboration with academic partners such as Collège de France and IS2M. The Na+ ion conductivity in the bulk of the electrolyte, as well as at the electrode-electrolyte interface (EEI), are the two major criteria that need to be optimized in electrolytes to enable the development of fast-charging Na-ion cells.

The first strategy to increase bulk conductivity will be to use less viscous co-solvents, such as ethers or nitriles. However, these solvents exhibit poor electrochemical stability. Therefore, as a first step, the impact of adding such co-solvents to the state-of-the-art Na-ion electrolyte in various proportions will be studied to (i) determine their electrochemical stability windows and (ii) analyze their solvation/desolvation behavior, which is critical for their power rate capabilities. The fluorinated counterparts of the most promising co-solvents will also be investigated to improve oxidative stability and enable the formation of a stable solid electrolyte interphase at the negative electrode.

The second approach will focus on identifying additives that lead to ‘non-resistive’ interphases. Both commercial and in-house synthesized additives will be explored for this purpose. By tuning the three electrolyte components together, new formulations will be developed to achieve a better compromise between fast Na?-ion kinetics and stable cycling performance of Na-ion cells.