Influence of annealing conditions on the ionic conductivity of Li3PO4-Li2SiO3 thin films prepared by magnetron sputtering

Li3PO4-Li2SiO3 thin films were prepared on the surface of Al2O3 fine ceramic substrates by radio frequency (RF) magnetron sputtering. The thin films were treated at different annealing temperatures (400-800 degrees C) and for various time (0.5 h, 1 h,1.5 h, and 2 h) to investigate the influence of annealing conditions on the ionic conductive properties. The as -deposited and annealed thin films were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) to study the physical and structural features. Electrochemical impedance spectra (EIS) was carried out from 25 degrees C to 500 degrees C to analyze the temperature dependence of ionic conductivity. The results indicate that the crystalized Li3PO4-Li2SiO3 thin films possess an enhanced ionic conductivity compared with crystallized single Li3PO4 and Li2SiO3 thin films. Moreover, the Li3PO4-Li2SiO3 compound thin films exhibit a negative correlation between the ionic conductivity and annealing temperature, while the annealing time also showed similar passive effect on the conductivity. The Li3PO4-Li2SiO3 compound thin films with enhanced ionic conductivity are suggested to exert good performance in lithium ion batteries and other lithium dominated conductors.