Probing the morphological influence on solid electrolyte interphase and impedance response in intercalation electrodes

Abstract

Solid electrolyte interphase (SEI) formation, due to the electrochemical reaction between the salt and solvent in the electrolyte, is a key contributor to the electrode performance decay in lithium-ion batteries. The active particle morphology and electrode microstructure affect the side reaction rate and hence the SEI induced interfacial transport and impedance behavior. The change resistance due to the variation of SEI thickness can be inferred from electrochemical impedance spectroscopy. In this study, we proposed a microstructure-aware impedance model to predict the effect of electrode microstructure on impedance response. Our model successfully captures the influence of active particle morphology on the SEI formation and corresponding impedance characteristics. Different electrode realizations with microstructural and compositional variations have been considered. The critical influence of active material morphology, mean particle size, binder and electrolyte volume fractions on the SEI formation and impedance behavior reveals the underlying interdependences of the interfacial and transport resistance modes.