Effect of bottleneck size on lithium migration in lithium garnets Li7La3Zr2O12 (LLZO)

Molecular dynamic simulations were performed on element-screened Li7La3Zr2O12 (LLZO)-equivalent doping system to reveal the effect of bottleneck (surface between the polyhedron of 24d and 96h site in cubic LLZO) size on lithium ion diffusion in this garnet-type solid electrolyte. The relationship between lithium ion diffusivity, lattice constant (volume), and bottleneck size were further studied. Herein, we found unneglectable discreteness between lattice constant (volume) and lithium ion diffusivity; beyond that, a quasi-linear relationship between bottleneck size and lithium ion diffusivity under high temperature (1000~1400 K) was unveiled. Our results show that by simply regulating the bottleneck size, the diffusion properties of lithium garnets can be further improved.