Atomic Origin of Chemomechanical Failure of Layered Cathodes in All-Solid-State Batteries.

The ever-increasing demand for safety has thrust all-solid-state batteries (ASSBs) into the forefront of next-generation energy storage technologies. However, the atomic mechanisms underlying the failure of layered cathodes in ASSBs, as opposed to their counterparts in liquid electrolyte-based lithium-ion batteries (LIBs), have remained elusive. Here, leveraging artificial intelligence-enhanced super-resolution electron microscopy, we unravel the atomic origins dictating the chemomechanical degradation of technologically crucial high-Ni layered oxide cathodes in ASSBs. We reveal that the coupling of surface frustration and interlayer-shear-induced phase transformation exacerbates the chemomechanical breakdown of layered cathodes. Surface frustration, a phenomenon previously unobserved in liquid electrolyte-based LIBs, emerges through electrochemical processes involving surface nanocrystallization coupled with rock salt transformation. Simultaneously, delithiation-induced interlayer shear yields the formation of chunky O1 phases and intricate interfaces/transition motifs, distinct from scenarios observed in liquid electrolyte-based LIBs. Bridging the knowledge gap between the failure mechanisms of layered cathodes in solid-state electrolytes and conventional liquid electrolytes, our study provides unprecedented atomic-scale insights into the degradation pathways of layered cathodes in ASSBs.