Mechanical Failure of Solid-State Electrolyte Rooted in Synergy of Interfacial and Internal Defects

The mechanical failure of solid-state electrolytes induced by the growth of the lithium metal anode hinders the development of solid-state Li metal batteries with good safety and high energy density, and thus the understanding of the failure mechanism is of high importance for the application of solid-state lithium-metal batteries. Herein, a modified electro-chemo-mechanical model is built to bridge the dynamic relationship between the mechanical failure of solid-state electrolytes and the electrodeposition of lithium metal. The results, visualize evolution of local stress fields and the corresponding relative damage, and indicate that the generation of damage inside the solid-state electrolyte is rooted in a synergy of interfacial and internal defects. Compression by electrodeposited lithium inside interfacial defects and further transmission of stress inward in the electrolyte causes catastrophic damage, which is determined by the geometry of interfacial defects. Moreover, the internal defects of the solid-state electrolyte from sintering can influence the pathway of damage and work as the inner fountainhead for further damage propagation, and as such, the position and amount of the internal voids exhibit a more competitive role in the mechanical failure of solid-state electrolyte. Thus, the synergetic failure mechanism of solid-state electrolytes raised in this work provides a modeling framework to design effective strategies for state-of-the-art solid-state lithium-metal batteries.