Atomic-scale observation of lithiation reaction front in nanoscale SnO ₂ materials

In the present work, taking advantage of aberration-corrected scanning transmission electron microscopy, we show that the dynamic lithiation process of anode materials can be revealed in an unprecedented resolution. Atomically resolved imaging of the lithiation process in SnO₂ nanowires illustrated that the movement, reaction, and generation of b = [1Ì...1Ì...1] mixed dislocations leading the lithiated stripes effectively facilitated lithium-ion insertion into the crystalline interior. The geometric phase analysis and density functional theory simulations indicated that lithium ions initial preference to diffuse along the [001] direction in the {200} planes of SnO₂ nanowires introduced the lattice expansion and such dislocation behaviors. At the later stages of lithiation, the Li-induced amorphization of rutile SnO₂ and the formation of crystalline Sn and Li_xSn particles in the Li₂O matrix were observed.