Self-consolidation mechanism and its application in the preparation of Al-doped cubic Li7La3Zr2O12

Abstract

For the preparation of high-density ceramic electrolytes, researchers prefer cold or hot isostatic pressing method, which is not cost effective because of the ultra-high pressure and poor productivity. In this paper, we present a novel “self-consolidation” method to prepare dense cubic Al-doped Li7La3Zr2O12 (LLZO) without the assist of pressing. The relative density of LLZO bulk sample is about 93–96%, and the 0.10 mol Al-doped sample with the purest cubic structure possesses the highest total ionic conductivity of 1.41 × 10− 4 S cm− 1 at 30 °C, which is comparable to the conductivities of the samples prepared by traditional high-pressure methods. Furthermore, a LLZO crystal unit cell model is constructed and the self-consolidation mechanism for LLZO from crystal unit cell to bulk is explored. The surface tension of the molten Li compounds acts as the intrinsic power for the self-consolidation. This work demonstrates a facile, productive and reliable route for the preparation of dense cubic LLZO, and provides an important insight into the microscopic consolidation mechanism of ceramic electrolytes.