Solid electrolytes for lithium batteries

Abstract

The use of solid electrolytes to produce an all-solid-state lithium battery is regarded as one promising alterative for improved safety. In this work, the researchers synthesized cubic garnet-type ceramic electrolyte Li6.75La3Zr1.75Ta0.25O12 (LLZTO) via the coprecipitation method. For the characterization, the phase content was determined using X-ray diffraction (XRD), morphology was obtained by using a scanning electron microscope (SEM), and conductivity was measured by AC impedance spectroscopy using a frequency response analyzer. The results showed that the room temperature total conductivity and activation energies of LLZTO were 7.2 × 10-6 S/cm and 0.31 - 0.46 eV, respectively. Composite electrolytes were prepared by mixing LLZTO with a ceramic (Li1.4Al0.4Ti1.6(PO4)) (NASICON) or a polymer polyethylene oxide (PEO) with LiClO4 salt. The LLZTO-NASICON composite showed a higher total conductivity of 1.2 × 10-5 S/cm and activation energies of 0.23 - 0.58 eV. Compared to LLZTO, the LLZTO-PEO(LiClO4) composite showed a similar room temperature total conductivity of 1.2 × 10-6 S/cm, but a higher activation energy of 0.59 - 0.85 eV.