Investigations on electrical conductivity and chemical compatibility between fast lithium ion conducting garnet-like Li6BaLa2Ta2O12 and lithium battery cathodes

Garnet-like metal oxide with the nominal chemical composition Li6BaLa2Ta2O12 was prepared by conventional solid-state reaction method. It shows mainly bulk contribution to the total lithium ion conductivity. The thick and thin Li6BaLa2Ta2O12 pellets exhibit similar lithium ion conductivity over the investigated temperature range (RT-370 °C). The chemical compatibility between garnet-like Li6BaLa2Ta2O12 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.% Li6BaLa2Ta2O12 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 Li6BaLa2Ta2O12 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 Li6BaLa2Ta2O12 electrolyte for galvanic cell applications (e.g., batteries).