Boundary effect on the plasticity and stress of lithiated silicon: First-principles calculations

Silicon anode experiences large volumetric change (∼400) during lithiation in lithium ion batteries, which induces fracture and plasticity. In this paper, the boundary effect of silicon nanofilms on the structural evolution, plasticity, stress, and strain during lithiation is studied by first-principles calculations. It is found that rigid boundary induces compression stress and structural disruption during lithiation, as well as voids and plastic deformation during delithiation. In contrast, free boundary allows silicon to expand freely and release the stress during lithiation. Moreover, the volume expansion of the lithiated Si is totally recoverable during delithiation and thus the deformation is entirely elastic.