Elucidating the Nature of Grain Boundary Resistance in Lithium Lanthanum Titanate

Symington, A. R.; Molinari, M.; Dawson, J. A.; Statham, J. M.; Purton, J.; Canepa, P.; Parker, S. C.

doi:10.1039/D0TA11539H

Elucidating the Nature of Grain Boundary Resistance in Lithium Lanthanum Titanate

A. R. Symington, M. Molinari, J. A. Dawson, J. M. Statham, J. Purton, P. Canepa, and S. C. Parker; J. Mater. Chem. A 9, 6487–6498 (2021).

BibTeX

@article{Symington2021elucidating,
  author  = {Symington, A. R. and Molinari, M. and Dawson, J. A. and Statham, J. M. and Purton, J. and Canepa, P. and Parker, S. C.},
  title   = {{Elucidating the Nature of Grain Boundary Resistance in Lithium Lanthanum Titanate}},
  journal = {Journal of Materials Chemistry A},
  volume  = {9},
  pages   = {6487--6498},
  year    = {2021},
  doi     = {10.1039/D0TA11539H}
}

Brief summary

Solid electrolytes are made of many small grains, and the boundaries between them matter. Molecular dynamics of the perovskite lithium lanthanum titanate (LLTO) show that its grain boundaries cut lithium conductivity by ten to a hundred times compared with the crystal, because their structure is strongly distorted.

Full abstract

Solid electrolytes for all-solid-state batteries are generating remarkable research interest as a means to improve safety, stability and performance of rechargeable batteries. Solid electrolytes are often polycrystalline and the effect that grain boundaries have on the material properties is often not fully characterised. Here, we present a comprehensive molecular dynamics study that quantifies the effect of grain boundaries on Li-ion transport in perovskite Li_3xLa_(2/3)-xTiO₃ (0 < x < 0.16) (LLTO). Our results predict that grain boundaries hinder Li-ion conductivity by 1 to 2 orders of magnitude compared to the bulk. We attribute the poor Li-ion conductivity of the grain boundaries to significant structural alterations at the grain boundaries. Our detailed analysis provides important insight into the influence of grain boundary structure on transport of Li-ions in solid electrolyte materials.