Stable LATP/LAGP double-layer solid electrolyte prepared via a simple dry-pressing method for solid state lithium ion batteries

In this paper, a NASICON-type Li1.3Al0.3Ti1.7(PO4)(3) (LATP)/Li1.3Al0.3Ge1.7(PO4)(3) (LAGP) bi-layer structured solid state electrolyte was successfully prepared via a simple dry pressing and post-calcination method. By adjusting the sintering temperature for LAGP starting materials, a dense and smooth LATP/LAGP double-layer solid state electrolyte with no defects was obtained. This electrolyte sample exhibits a high electrical conductivity of 3.4 x 10(-4) S cm(-1) and a negligible electronic conductivity of 9.6 x 10(-9) S cm(-1) at room temperature. In addition, the LATP/LAGP electrolyte also shows an excellent stability in air as well as chemical stability against Li. Moreover, an assembled LiFePO4/LATP-LAGP/Li coin-type battery employing LATP/LAGP as the solid state electrolyte can be suitably charged and discharged at a current rate of 0.1C at room temperature, and its low charge-discharge capacities are mainly attributed to the high electrolyte/electrode interfacial resistance of the cell. These results suggest that the LATP/LAGP bilayer electrolyte can be an alternative electrolyte for all-solid-state lithium-ion batteries.