Structural properties of LATP ceramic pellets sintered at 900°C and modified by a novel solution-immersion densification process

Abstract

The high temperature sintered ceramic pellets of solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP), obtained in the absence of any sintering aids, should contain a large amount of interparticle gaps, which is one of the main bottlenecks in developing LATP-based all-solid-state Li-metal batteries. In this study, a facile solution (LiCl in ethanol) immersion method is adopted to soak the already 900℃-sintered LATP ceramic pellets, and the resulting series of LATP-xLiCl (x denotes the weight fraction of LiCl, 0.0 ≤ x ≤ 3.7) are assayed to address the high-performance mechanism of lithium-graphite (Li-C) symmetric cells. At the optimal x value of 2.3, the grain-boundary resistance of the ceramic pellet can be significantly reduced from 1772 to 28 Ω·cm² at room temperature, which endows the Li-C symmetrical cells of LATP-2.3LiCl with a high critical current density of 3.00mAcm² at 60°C. Especially, the enhanced ionic conductivity of LATP-2.3LiCl (4.7×10-4 S cm-1, at 20℃; 1.1×10-3Scm-1, at 60℃) indicates an effective strategy of utilizing capillary force to densify LATP-based ceramic pellets for potential application purposes.