Investigations on electrical conductivity and chemical compatibility between fast lithium ion conducting garnet-like Li₆BaLa ₂Ta₂O₁₂ and lithium battery cathodes

Garnet-like metal oxide with the nominal chemical composition Li ₆BaLa₂Ta₂O₁₂ was prepared by conventional solid-state reaction method. It shows mainly bulk contribution to the total lithium ion conductivity. The thick and thin Li₆BaLa ₂Ta₂O₁₂ pellets exhibit similar lithium ion conductivity over the investigated temperature range (RT-370 °C). The chemical compatibility between garnet-like Li₆BaLa₂Ta ₂O₁₂ and several potential lithium battery positive (cathode) electrodes that includes LiCoO₂, LiNiO₂, LiMn₂O₄ and Li₂MMn₃O₈ (M = Fe, Co) was investigated by powder X-ray diffraction (XRD). 1:1 wt.% Li ₆BaLa₂Ta₂O₁₂ and electrode powders were mixed and heated in the temperature range 400-900 °C for 24 h in air. The powder XRD data reveals that Li₆BaLa₂Ta ₂O₁₂ is stable against chemical reaction with layered structure LiCoO₂ over the investigated temperature range, while the Mn, (Co, Mn), (Fe, Mn) and Ni containing electrodes were found to react above 400 °C. Accordingly, LiCoO₂ electrode may be considered as potential positive electrode with Li₆BaLa₂Ta ₂O₁₂ electrolyte for galvanic cell applications (e.g., batteries).