Solid-state batteries with a lithium–metal anode are energy-storage devices that promise increased energy density and improved safety compared with liquid systems. Despite significant developments, the chemomechanical degradation of solid-state batteries represents a significant challenge to their widespread adoption. Specifically, Li-filled cracks (called “dendrites”) and electronically isolated Li inclusions (“dead” Li) are key defects resulting from coupled electrochemical and mechanical degradation during cycling. In this study, we use a symmetrical Li|LLZO|Li cell with a single-crystal electrolyte and demonstrate that an electronically isolated Li-metal inclusion exhibits bipolarity under an external electrical field, which leads to further crack expansion. We suggest that this process of “dead” metal activation accelerates chemomechanical degradation in solid-state batteries with alkali anodes.

These data correspond to the publication with the DOI: https://doi.org/10.1021/acsenergylett.5c00101. The data represent .txt files corresponding to electrochemical measurements and images of cell assembly and disassembly as stated in the Methods section. The data also comprise operando measurements corresponding to the Supplementary Materials submission.