Electrochemistry of Lithium against ionic liquids; modelling the influence of “dielectric” solvents as additives

Here at imec, we are evaluating various ionic liquid-based electrolytes (ILEs) for successfully mitigating the issues faced by Li anodes. Of importance here is the electrical double layer (EDL) that is formed at the vicinity of the reactive Li metal, which dictates the formation of the so-called solid electrolyte interphase (SEI). The nature and properties of the EDL and the SEI can be controlled by changing the composition of the ILEs (concentration of the salt, cosolvent) as well as by chemical/electrochemical preconditioning. In this project, the effect of various cosolvents and their concentration will be evaluated. Cosolvents change the coordinating structure around Li+ and hence the effective charge in its solvation environment in the electrolyte. This in turn affects structure of the interphase layer and Li0 plating (deposition) potential. During stripping (dissolution) cycle, Li+ ions move through this interphase layer and hence, the entire process of deposition/dissolution is changed by addition of cosolvents. 

The prospective student will examine the effect of variation cosolvent concentration in ILE’s and systematically study the resulting changes in physical and electrochemical properties of Li deposition/dissolution process. Such fundamental knowledge can be a starting point to successfully engineer superior functioning Li anodes.