Fabrication and electrochemical properties of Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes by sol-gel method

Sodium super ionic conductor (NASICON)-type solid electrolytes, Li1.3Al0.3Ti1.7(PO4)3 (LATP), have high lithium ion conductivity and chemical/electrochemical stability. In this study, we proposed a new sol-gel route to synthesize LATP precursor powder. The LATP powder was prepared from lithium nitrate (LiNO3), aluminum phosphate (AlPO4), ammonium phosphate (NH3PO4), and titanium isopropoxide (Ti-(OCH(CH3)2)4). The LATP electrolyte with high relative density (99%) and lithium ion conductivity (4.2 × 10−4 S/cm at 30 °C) could be fabricated by sintering the precursor powder at 1000 °C for 6 h. XRD analysis results revealed that the electrolyte sample sintered at 1000 °C for 6 h was impurity-free single phase LATP. FE-SEM observations showed that the grain size and density increased with increasing sintering temperature. AC impedance spectra and SEM observations suggest that the enhanced lithium ion conductivity was due to an increase in grain size and density of the LATP electrolyte.