Garnet solid-state electrolyte: A new single-step elaboration by electric arc-melting

The garnet Li7-xLa3Zr2-xTaxO12 (LLZTO) has attracted a real scientific interest in the last decade as it is one of the safest solid-state electrolytes for next generation high energy lithium batteries. However, its elaboration requires several steps from phase stabilization to densification of the part. This final step, with long and high temperature treatment induces lithium loss due to sublimation. Electric arc-melting allows short time elaboration of dense parts in one-step, eventually minimizing Li sublimation. Thus, the synthesis by arc-melting of LLZTO is exposed here. Stabilized phases and microstructures are studied depending on chemical composition and casting parameters. The direct obtaining of dense parts instead of powder allows better moisture stability thanks to fast growth of protective layer preventing in-depth penetration of the H+/Li+ exchange. Finally, ionic conductivity of fused parts is in a similar range to sintered pellets produced using Spark Plasma Sintering with powdered fused parts. Those results confirm the interest of electric arc-melting synthesis as an alternative LLZTO elaboration. •Fused raw powders are cast to obtain dense cubic LLZO with only 0.4 Ta pfu.•Thickness of cast samples can be tuned.•Grains >50 μm in diameter are stabilized with homogeneous repartition of elements.•Ground powder can be processed by SPS.