Microstructure evolution and transport properties of garnet-type Li_6.5La_2.5Ba_0.5TaZrO₁₂ electrolyte for all-solid-state Li-ion batteries

The garnet-type Li_6.5La_2.5Ba_0.5TaZrO₁₂ (LLBTZO) electrolyte for Li-ion battery was synthesized by doping tantalum (Ta) and barium (Ba) in Li₇La₃Zr₂O₁₂ (LLZO) via solid-state method at different sintering temperatures (1100, 1150 and 1200 °C). The as-prepared sintered compositions were characterized for their physical properties using X-ray diffraction (XRD) which confirmed the formation of desired cubic phase of LLBTZO. The material was further investigated by using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and He-pycnometer to study morphological and electrochemical properties. Increasing the sintering temperature from 1100 to 1200 °C led to more than 60-fold increase in the ionic conductivity at 26 °C from 1.07 × 10⁻⁶ to 6.62 × 10⁻⁵ S/cm, which can be attributed to evolution of microstructures. With increasing sintering temperature, more of the powder surface is eliminated, the density of the resulting pellet was increased, and thus the total conductivity was enhanced.