Chemo-electro-mechanical phase-field simulation of interfacial nanodefects and nanovoids in solid-state batteries

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