Doping Implications of Li Solid State Electrolyte Li7La3Zr2O12

04 March 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Solid-state electrolytes, like Li7La3Zr2O12 (LLZO), can enable safer, more energy dense and longer lasting batteries. However, there are still challenges concerning dendrite formation and poor Li-ion conductivity. Here we investigate the effect of Al, Ga, Nb, Ta, and Y doping of LLZO using hybrid density functional theory calculations. The inferred site preferences of Al, Ga, Nb, and Ta result in donor defects that stabilise additional Li vacancies. More Li vacancies lead to increased disorder on the Li sublattice, thus predicting a stabilisation of the more ionic conducting cubic phase. Furthermore, our calculations indicate that the effect of the dopants on the sintering process is even more important than the ability to induce more ionic charge carriers. Finally, differences in Li vacancy formation energies suggest a new possible explanation for the two orders of magnitude increase in ionic conductivity upon stabilising the cubic phase.

Keywords

LLZO
solid state electrolyte
SSE
battery
Li-ion
hybrid dft
defects
doping
Li7La3Zr2O12
Al-doping

Supplementary materials

Title
Description
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Title
Doping Implications of Li Solid State Electrolyte Li7La3Zr2O12 - Supporting Information
Description
Contains: HSE06 optimised lattice parameters for LLZO, HSE06 optimised atomic positions for LLZO, Calculated dielectric tensor for LLZO, Structure figures, chemical potential stability region, Kröger-Vink equations for dopants, Formation energies and kpoints for limiting phases with both PBEsol and HSE06, PBEsol transition level diagrams, HSE06 density of states, x/0 transition levels above the VBM.
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