Modeling of Electrochemical Performance and its Relation to Mechanical Responses of Li Metal Batteries

Abstract

The development and commercialization of Li metal batteries are hindered by safety challenges. Accordingly, significant efforts have been made to improve the stability of Li anodes. However, only a few studies have focused on the impact of mechanical deformation caused by Li deposition at the cell level. The strain changes are considerably large and should be further investigated for their mechanical impact. Therefore, in this study, we focused on the development of a physics-based model for Li metal batteries. To the best of our knowledge, this is the first attempt to develop a model that can describe the electrochemical and mechanical responses of a full Li metal cell with different material properties, external pressures, and boundary conditions. The Young's modulus and higher expansion ratio of the negative electrode increase overall stress generation. However, overall cell pressure decreases with an increasing expansion ratio of the positive electrode. This is because the positive electrode contracts in response to the significant expansion of the lithium metal. The current model provides insights into the mechanisms by which these factors affect the electrochemical and mechanical behaviors of Li metal cells. This model provides guidance for battery design and management of Li metal cells.