Underpinnings of Multiscale Interactions and Heterogeneities in Li‐Ion Batteries: Electrode Microstructure to Cell Format

Lithium‐ion batteries exhibit a coupled set of electrochemical, thermal, and mechanical interactions ranging over different length scales. Microstructure‐scale electrode characteristics govern the intrinsic and kinetic processes and lead to distinct signatures in electrochemical performance and degradation (e.g., lithium plating). Accurate prediction of cell response relies on advanced physics‐based models that can analyze the spatial heterogeneity in pore‐scale and electrode‐scale features. Herein, a hierarchical modeling framework that captures the mechanistic interactions stemming from electrode microstructure and systematically connects this to the lithium‐ion pouch cell performance/degradation response is developed. In conjunction with the microstructural arrangement, the roles of cell format on spatiotemporal heterogeneity in intercalation/plating dynamics, internal heat generation, and mechanical stresses across the pouch cell that are important aspects for fast charging are analyzed. Based on the cell design and operating conditions, unique attributes with respect to the location of plating onset, presence of thermal/mechanical hotspots, and the manifestation of temperature gradients across the pouch cell. are delineated. This study provides a mechanistic understanding of the multiscale interactions and heterogeneity underlying the electrochemical–thermal–mechanical response of lithium‐ion batteries, critical for operational extremes such as fast charging.