Production of Li1.5Al0.5Ge1.5(PO4)3 ionic conductor from liquid-phase precursors

Abstract

Abstract The synthesis of lithium-conducting solid electrolyte Li1.5Al0.5Ge1.5(PO4)3 (LAGP) from liquid-phase precursors using available water-soluble salts (LiNO3·3H2O, Al(NO3)3·9H2O, (NH4)2HPO4) and a stable citrate [Ge(C6H5O7)3]5– or oxalate [Gе(С2О4)3]2– germanium complex was studied. Germanium complexes were obtained by dissolving the hexagonal modification of GeO2 in citric or oxalic acid. As a result of the transfer of all initial components to the solution with the formation of a true collective solution, the subsequent interaction proceeded with the formation of a single-phase LAGP product in one stage from an oxalate precursor at 650°C, from a citrate precursor — at 800°C. The synthesized LAGP was studied by XRD, TG-DSC, IR spectroscopy, chemical analysis and impedance spectroscopy. The total ionic conductivity at room temperature was 8·10–4 S/cm and 2.5·10–4 S/cm for LAGP synthesized from oxalate and citrate precursor respectively. LAGP synthesis from oxalate precursor is preferred over synthesis from citrate precursor.