A Chemo-Mechanical Grain Boundary Model and Its Application to Understand the Damage of Li-Ion Battery Materials
15 Pages Posted: 22 Dec 2019 First Look: Under Review
Although the unique mechanical and transport features of grain boundary (GB) in polycrystalline ion conductors have been recognized, the study on the chemo-mechanical interplay and its impact is insufficient. We present a coupled GB model, which includes both the damage-dependent across-grain transport and the mechanical cohesive zone law. 3D simulations on LiNixMnyCozO2 demonstrate that the chemical process and the mechanical degradation go hand-in-hand: the enhanced intergranular chemical inhomogeneity challenges the GB mechanical strength, while the GB damage influences or even blocks the across grain transport. Results explain well the experimentally observed features including chemical hot spots and surface layer delamination.
Keywords: grain boundary, fragmentation, ion transport, NMC particles, crack propagation
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