Improvement of the conductivity of sol-gel derived Li-La-Zr-O thin films by the addition of surfactant

Li–La–Zr–O thin films were successfully fabricated using the sol-gel spin coating method and the effects of the addition of surfactant in the solution were studied. X-ray diffraction, scanning electron microscopy and Atomic Force Microscope were used to investigate the characteristics of these films and an amorphous structure and smooth surface on the films were revealed. The ionic conductivity of the film was investigated by impedance analysis. The results showed that the room-temperature ionic conductivity of the film increases with the content of surfactant, from 1.8 × 10 −6   S/cm for 0.5   wt% to 3.9 × 10 −6   S/cm for 1.5   wt%. However, further increasing the content of surfactant can deteriorate the property of the thin film on the contrary. The improvement of the property can be attributed to the improvement of the morphology of the film. We propose that this Li–La–Zr–O thin film is a promising solid electrolyte for thin-film lithium-ion batteries.