Heterogeneities affect solid-state battery cathode dynamics

Solid-state batteries hold the promise to improve energy and power densities compared to conventional lithium-ion batteries. Among myriad interface and mechanistic challenges plaguing the solid-state batteries, the composite cathode architecture owing to the underlying microstructural heterogeneity poses a critical bottleneck. The spatial variability of solid-solid point contacts and ionic/electronic percolation pathways govern the underlying reaction-transport dichotomy, and ultimately affect the spatio-temporal dynamics. In this work, we postulate the inherent role of mesoscale interactions and delineate how heterogeneities profoundly affect the spatio-temporal evolution of thermo-electrochemical dynamics subject to physical and operational extremes. This study critically examines the importance of solid-solid point contacts manifesting as singularities in thermo-electrochemical hotspot formation, intercalation cascade, and reaction current localization and establishes these as mechanistic pain points for consideration in the future development of improved solid-state battery cathode architectures.