Structural Properties of the 900°C-Sintered Latp Ceramic Pellets Modified by a New Kind of Solution-Immersion Densification Processing

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 inter-particle 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 900°C-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, it is a significant decrease of the ceramic pellet’s grain-boundary resistance (4378 → 71 Ω) at room temperature that makes the Li-C symmetric cells of LATP-2.3LiCl to endow with a high critical current density of 3.00 mA cm−2 at 60°C. Especially, the enhanced ionic conductivity of LATP-2.3LiCl (4.7×10-4 S cm-1, at 20°C; 1.5×10-3 S cm-1, at 60°C) indicates an effective strategy of utilizing capillary force to densify LATP-based ceramic pellets for potential application purposes.

Keywords: Solid electrolyte, Ionic conductivity, Grain boundaries, Porosity, Solution immersion