Influence of sintering aid on the microstructure and conductivity of the garnet-type W-doped Li₇La₃Zr₂O₁₂ ceramic electrolyte

Li_6.4La₃Zr_1.7W_0.3O₁₂ (LLZWO) garnet-type structure was prepared with SiO₂ as sintering aid via solid-state reaction method. The prepared ceramic samples were characterized by X-ray diffraction and Raman spectra to judge the structure. Microstructure, lithium-ion conductivity and electronic conductivity of all components were investigated by means of scanning electron microscopy, electrochemical impedance spectroscopy and potentiostatic polarization measurement, respectively. These investigations show that SiO₂ was found to be a better additive to reduce the porosity and improve conductivity. The relative density and ionic conductivity increase first and then decrease with increasing SiO₂ content. The relative density of 93.8% and ionic conductivity of 9.11 × 10⁻⁴ S cm⁻¹ in the sample with 0.2 wt% SiO₂ were obtained. In contrast, the activation energy reaches a minimum value of 0.38 eV.