Chemo-electro-mechanics of nanodefects in solid-state batteries: A phase-field simulation

Abstract

Abstract Solid electrolytes (SEs) encompass various types of nanodefects, including grain boundaries (GBs) and nanovoids at the Li metal/SE interface, where lithium dendrite penetration has been extensively observed. Despite the importance of ion transport near GBs with different anisotropy and the combinatorial effects with interfacial nanovoids, a comprehensive understanding of these phenomena has remained elusive. This study develops an electro-chemo-mechanical phase-field model to elucidate how Li penetrates Li7La3Zr2O12 (LLZO) in the co-presence of GBs and interfacial nanovoids. The investigation unveils a GB-anisotropy-dependent behavior for Li-ion transport correlated with the presence of interfacial nanovoids. Notably, the Σ1 GB exhibits faster Li dendrite growth, particularly in the co-presence of interfacial nanovoids. The model quantitatively reveals whether interfacial electronic properties dominate Li deposit morphology and penetration, providing a strategy for designing stable Li/SE interfaces. These findings help prioritize approaches for optimally tailoring nanodefects and exploiting synergetic effects at the interface to prevent dendrite formation.