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In solid-state battery devices, the ceramic solid electrolytes (SE) are promising replacements to the existing liquid electrolytes due to their higher thermal stability. There are several SE studied in CMC group such as LLZO (Li7La3Zr2O12), NASICON (Na1+xZr2SixP3-xO12) and LATP (Li₁₊ₓAlₓTi₂₋ₓ(PO₄)₃).
Our recent studies show that the Li and Na ions redistribution during synthesis and working conditions strongly varies based upon:
- Doping: Ta, Nb, Ga or Al doping can have a drastic impact on Li redistribution and conductivity in the SE.
- Microstructure: polycrystalline SEs exhibit higher Li or Na inhomogeneities in the bulk than in monocrystalline SEs.
- Synthesis conditions: for example higher is the temperature during the crystal growth higher is the Li inhomogeneity in the SE (proved for LLZO case doped with Nb).
The Li inhomogeneity can be mapped down to the atomic level and in 3D as schematized below. The bigh advantage of this study is that, contrary to other characterization techniques, both ultra-light atoms (such as Li) and ultra-heavy elements (such as Ta) are detected with equal sensitivity by atom probe tomography. The 3D map on the right clearly shows the strong Li accumulation at the grain boundary of a polycrystalline Ta-doped LLZO.
