Li sublattice and diffusive response to uniaxial loads in the solid electrolyte, Li7La2Zr3O12 (LLZO)

Scott Monismith, Jianmin Qu

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The polymorphism of the garnet solid electrolyte, Li7La3Zr2O12 (LLZO), is a critical facet of the material's performance and viability as an electrolyte candidate. Indeed, the cubic polymorph has an ionic conductivity several orders of magnitude higher than the tetragonal polymorph. While the transition from tetragonal to cubic LLZO has been reported over a range of temperatures, the response of the material to asymmetrical mechanical loads is not fully understood. To fill the knowledge gap, this paper conducted classical molecular dynamics (MD) simulations to investigate the diffusive response of LLZO under uniaxial stress conditions at 1000 K. It is found that the transition from cubic to tetragonal LLZO occurs around 500 MPa in compression and 750 MPa in tension. Near these threshold stresses, the Li sublattice undergoes a smooth transition from a cubic-like arrangement of interstitial occupancies to a tetragonal-like arrangement, with the occupancies of 24d and 96h interstitial sites decreasing and increasing respectively as the stress increases. The activation energy for diffusion increases with both tension and compression, increasing at a rate of 39 × 10−6 and 7 × 10−6 eV/MPa in compression and tension respectively.

Original languageEnglish
Article number101671
JournalExtreme Mechanics Letters
Volume52
DOIs
StatePublished - Apr 2022

Keywords

  • Batteries
  • Computational science
  • Energy storage
  • Materials science
  • Solid electrolytes
  • Transport

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