The Electro-Chemo-Mechanical Coupling in Lithium Alloy Electrodes and Its Origins

Abstract

A method to identify and separate the influence of changes in the surface stress from the bulk stress in a model lithium-ion battery electrode during electrochemical cycling was developed. The strategy for this separation is based on the different influence of surface and bulk stresses on the coupling between electrode potential and mechanical strain as measured by dynamic electro-chemo-mechanical analysis and the coupling between the transferred electric charge and the elastic strain as determined by wide angle X-ray scattering. Using both methods, it was possible to uncover the behavior of an apparent surface stress evoked by the bulk stress due to grain boundary alloying of lithium in a gold film. Additionally, the analysis allowed for a determination of a range in surface stress due to underpotential deposition of one monolayer of lithium as the interval between −3.1 to −1.9 N/m.