Production of Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3 ionic conductor from liquid-phase precursors

摘要

The synthesis of lithium-conducting solid electrolyte Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3 (LAGP) from liquid-phase precursors using available water-soluble salts (LiNO_3·3H_2O, Al(NO_3)_3·9H_2O, (NH_4)_2HPO_4) and a stable citrate [Ge(C_6H_5O_7)_3]~(5-) or oxalate [Ge(C_2O_4)_3]~(2-) germanium complex was studied. Germanium complexes were obtained by dissolving the hexagonal modification of GeO_2 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.