Room-temperature ionic conductivity of Ba, Y, Al co-doped Li₇La₃Zr₂O₁₂ solid electrolyte after sintering

Abstract

The Ba, Y and Al co-doped Li₇La₃Zr₂O₁₂ (LLZO) was prepared by the solid-state reaction method. Effect of sintering on the crystallographic structure, morphology, total conductivity, relative density and contractibility rate of the prepared solid electrolyte was studied, respectively. The sintered samples were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), electrochemical impedance spectra (EIS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) techniques, respectively. The cubic garnet phase Ba, Y and Al co-doped LLZO is obtained, and the room-temperature total conductivity of the Ba, Y and Al co-doped LLZO solid electrolyte is improved significantly by eliminating the grain boundary resistances and improving the densifications with controlling sintering temperature (T) and time (t), respectively. Sintering at 1160–1190 °C for 12 h and at 1190 °C for 6–15 h, respectively, the Ba, Y and Al co-doped LLZO solid electrolytes are cubic garnet phase. Sintering at 1180–1190 °C for 12 h and at 1190 °C for 12–18 h, respectively, SEM images of the cross section of the Ba, Y and Al co-doped LLZO solid electrolytes exhibit the distinctively flattened morphology without any noticeable grain boundaries. The total conductivity, relative density and contractibility rate of Li_6.52La_2.98Ba_0.02Zr_1.9Y_0.1Al_0.2O₁₂ solid electrolyte are 2.96 × 10⁻⁴ S·cm⁻¹, 94.19% and 18.61%, respectively.