Electrochemical Impedance Spectroscopy: High-energy Battery Interphases - Prof Jelena Popovic-Neuber

Continuous solid #electrolyte interphase (SEI) and dendrite growth, as well as formation of ion blocking interfaces are some of the crucial issues preventing the commercialization of high energy density batteries depending on the implementation of alkali and alkaline earth metal anodes. Electrochemical impedance spectroscopy is a powerful tool to study processes in full #battery #cells, but also ion transport in naturally formed and artificial SEIs, and its evolution in time from model symmetric cells. The technique can be successfully used in batteries containing liquid, solid-state or hybrid electrolytes. In this talk, an overview on the recent studies on ion transport and evolution of SEIs on Li, Na, K, Mg, Al and most recently silicon anodes will be given. In natural SEIs formed in contact with liquid electrolytes such as carbonates, glymes, Grignards and ionic liquids close to open circuit voltage, main findings include changes from surface to diffusion controlled growth mechanism (Li), high porosity and predominant liquid transport pathways (Na), inherent mechanical instabilities (Mg) and large charge transfer resistances (Mg, Al). Artificial sulfide and Al2O3-based SEIs on Li and Na metal are also porous and reactive in contact with liquid and thiosulphate solid-state electrolytes. These findings are not only important in terms of optimization of metal anode behavior, but also in terms of understanding half-cell behavior when testing novel cathode materials.