Microstructure evolution and transport properties of garnet-type Li6.5La2.5Ba0.5TaZrO12 electrolyte for all-solid-state Li-ion batteries

The garnet-type Li6.5La2.5Ba0.5TaZrO12 (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 degrees 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 degrees C led to more than 60-fold increase in the ionic conductivity at 26 degrees C from 1.07 x 10(-6) to 6.62 x 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.