Sol-Gel-Derived Lithium Superionic Conductor Li1.5Al0.5Ge1.5(PO4)3 Electrolyte for Solid-State Lithium-Oxygen Batteries

Lithium aluminium germanium phosphate (LAGP) is attracting a great deal of attention as a solid electrolyte for lithium-oxygen (Li-O-2) batteries due to its high ionic conductivity. In this study, LAGP is prepared by a sol-gel process using comparatively low-cost GeCl2 as one of the reactants. The final product (LAGP) is obtained by sintering the dry precursor gel at 900 degrees C for 6 h. The influence of the duration of water evaporation during polymerization on the microstructure of LAGP has been examined. The structure, morphology, and electrochemical properties of LAGP are investigated by employing X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption analysis, and electrochemical impedance spectroscopy. XRD studies confirm the formation of Li1.5Al0.5Ge1.5(PO4)(3) as a primary phase along with small amounts of AlPO4 and Li2O as impurity phases. LAGP specimens have ionic conductivities in the range of 10(-4) to 10(-5) Scm(-1) at room temperature. In addition, LAGP also exhibits electrocatalytic activity towards the oxygen-reduction and evolution reactions. These results demonstrate the potential of LAGP prepared by sol-gel processes as a solid electrolyte for lithium-ion conduction in solid-state lithium-oxygen batteries.