Improving the Ionic Conductivity of Li1+xAlxTi2−x(PO4)3 in a Solid-State Synthesis by Regulating Li–O Bond with B3+ and Y3+

Abstract

Li1+xAlxTi2−x(PO4)3 (LATP) is a promising solid electrolyte owing to its high stability and ionic conductivity. But the ionic conductivity of LATP prepared by a conventional solid-phase method is usually one order of magnitude lower than the one prepared by the liquid-phase method. Herein, we achieve a high ionic conductivity of 1.2 mS·cm−1 by doping B3+ and Y3+ ions in LATP in a solid-state synthesis, and the roles of the dopants are revealed. The incorporation of B3+ and Y3+ in the lattice broadens the ion migration path and mitigates the Li+ migration energy barrier. On the other hand, the strong electrostatic interaction between B–O and Y–O bond weakens the electrostatic attraction between the Li–O bond, which makes the Li–O bond easier to break, and greatly improves the ion conductivity of LATP. This study sheds light on the facile solid-state synthesis of LATP with a high ion conductivity and accelerates the incoming practical application in the solid-state battery.