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Atomic-scale origin of the low grain-boundary resistance in perovskite solid electrolyte Li0.375Sr0.4375Ta0.75Zr0.25O3

The main achievement of this research is revealing the atomic-scale origin of the low grain-boundary (GB) resistance in Li0.375Sr0.4375Ta0.75Zr0.25O3 (LSTZ0.75) perovskite solid electrolyte and providing insights on overcoming the ubiquitous bottleneck of high GB resistance in other oxide solid electrolytes.

Significance of this scientific achievement 

  • Aberration-corrected scanning transmission electron microscopy and spectroscopy, along with an active learning moment tensor potential, were used to reveal the atomic scale structure and composition of LSTZ0.75 GBs.
  • Li depletion, which is a major cause for the low GB ionic conductivity of Li3xLa2/3-xTiO3(LLTO), was found to be absent for the GBs of LSTZ0.75.
  • A unique defective cubic perovskite interfacial structure that contained abundant vacancies was discovered at the GBs of LSTZ0.75. The authors attributed the low GB resistance of LSTZ0.75 to this microstructure.
  • Based on these results, the authors conclude vacancy and defect engineering can effectively improve GB ionic conductivity of solid Li-ion conductors, given that the material’s original structural framework should be maintained.

Contribution to IRG 1
This study provides new insights into the atomic-scale mechanisms of low GB resistance and sheds light on possible paths for designing compositionally complex oxide solid electrolytes with high total ionic conductivity.