Multi-scale mechanical-electrochemical coupled modeling of stress generation and its impact on different battery cell geometries

Abstract

Lithium-ion batteries are available in three primary configurations: cylindrical, prismatic, and pouch cells. The distinct shapes of these formats introduce variations in electrochemical performance and mechanical response. This study extensively investigates the influence of cell format on electrochemical and mechanical responses, expanding investigations with higher C-rates and next-generation battery materials exhibiting significantly larger expansion ratios. To the best of our knowledge, no simulation studies on large-scale cell format comparisons comprehensively considering the electrochemical and mechanical responses of the electrode design currently exist, especially for high expansion ratio materials. A physics-based 2D model integrating particles, electrodes, and cell levels was employed to achieve this, unraveling the interplay between mechanical and electrochemical reactions. Although stress improved electrochemical performance, the impact of geometric differences appeared minimal. However, significant volume expansion reduces the electrochemical performance and highlights format-driven variations, with pouch cells demonstrating superior electrochemical performance, followed by prismatic and cylindrical cells at 1C. The stress and strain patterns mimicked the concentration distributions, while the circular regions introduced uneven stress and deformation. Therefore, ensuring cell safety requires thicker separators in high-strain circular areas. This study presents a safe cell design, encompassing considerations of electrochemical and mechanical responses in current lithium-ion batteries and next-generation technologies.