High lithium-ion conducting NASICON-type Li1 + x − yAlxNbyTi2 - x − y(PO4)3 solid electrolytes

A water-stable lithium-ion conducting solid electrolyte with high conductivity and excellent mechanical properties has potential application for aqueous lithium-air batteries. In this study, a water-stable NASICON-type lithium-ion conducting solid electrolyte with a nominal composition of Li1 + x − yAlxNbyTi2 − x − y(PO4)3 was synthesized with variation of the Al and Nb contents using a conventional solid-state reaction method, and the electrical conductivity and mechanical properties were examined. The highest lithium-ion conductivity of 7.5 × 10− 4 S cm− 1 at 25 °C and the highest three-point bending strength of 110 N mm− 2 at room temperature were observed for Li1.30Al0.5Nb0.2Ti1.30(PO4)3 and Li1.35Al0.55Nb0.2Ti1.25(PO4)3, respectively. Li1.30Al0.5Nb0.2Ti1.30(PO4)3 was stable in a saturated LiOH aqueous solution with saturated LiCl.