Deformation of Lithium-Ion Battery Anodes during SEI Formation: a Probe for the Structure of the SEI
In this presentation, we present a new method to probe the structure of the SEI that is formed on lithium-ion battery anodes. A custom battery cell employs an unconstrained (i.e. not on a current collector) graphite composite electrode and allows optical access to the electrode during electrochemical cycling. Electrolyte is reduced on the electrode surface potentiostatically, and the resulting deformation of the electrode is measured using digital image correlation (DIC), an optical, full-field strain measurement technique. The amount of deformation of the electrode induced during SEI formation is related to the structure of the SEI layer. The strain measurements are then compared to galvanostatic cycling results, and the effects of different electrolyte salts, solvents, and additives on the SEI structure and battery capacity retention are evaluated.