Impedance of Lithium Electrodes in a Propylene Carbonate Electrolyte

Abstract

Different models of compact, porous, composite, and stratified surface layers have been investigated for the interpretation of impedance measurements of lithium electrodes in organic electrolytes.The surface layers are assumed to consist of organic and inorganic compounds with the properties of solid and polymer electrolytes.Comparison of predicted impedance spectra with those measured for surface layers formed in a molar solution of lithium perchlorate in propylene carbonate shows that two interphase models can be used to derive from the impedance measurements the thickness of surface layers in agreement with previous ellipsometric measurements.In a compact-stratified layer (CSL) model, the surface layer is assumed to consist of two sublayers of solid electrolyte with different conductivities; in a solid-polymer interphase (SPI) model, the surface layer is assumed to consist of a mixture of solid and polymer electrolytes. I. .