The influence of lithium sources on properties of perovskite-type lithium ion conductor

Highlights: • Li_0.33La_0.56TiO₃ was prepared by using different lithium sources. • Li₂CO₃-sourced LLTO achieved the highest total conductivity. • Higher conductivity was attributed to larger grains and higher ratio of cubic phase. -- Abstract: Perovskite-type lithium-ion conductor Li_0.33La_0.56TiO₃ was prepared via microwave sintering. The influence of lithium sources on the properties of the samples prepared and the compensation of lithium loss were investigated. XRD patterns, exhibiting a mixture of tetragonal and cubic phase, were all similar for the samples made with different lithium sources. The total conductivity of the sample made with Li₂CO₃ achieved 0.51 × 10⁻⁴ S/cm, which was the highest among all the samples made with different sources. The highest total conductivity of the sample made with Li₂CO₃ was attributed to the largest grains, which would result in a smaller concentration of less-conductive grain boundaries. The total conductivity of the sample compensated with 5% Li₂O was 38% higher than the sample made stoichiometrically. Given that grain sizes were similar for the samples compensated with a varied amount of Li₂O and the relative density of the sample compensated with 5% Li₂O was even the lowest among these samples, the highest total conductivity was rooted in the highest ratio of cubic phase. These results indicated that lithium sources could influence the properties of the LLTO samples greatly by resulting in a variation on crystalline phase, grain size, and relative density, which collectively determine the migration of lithium ions in polycrystalline Li_0.33La_0.56TiO₃.