ENGINEERING THE PERFORMANCE OF GARNET-TYPE Li7La3Zr2O12 CERAMIC ELECTROLYTES FOR SOLID STATE BATTERIES

Abstract

Solid state batteries employing lithium solid electrolytes emerge as a promising alternative to conventional lithium ion batteries owing to its potential high energy density and improved safety. Among various solid electrolytes, Garnet-type Li7La3Zr2O12 (LLZO) ceramic electrolyte is one of the most promising candidates. However, the realization of LLZO-based solid state batteries is still hindered by several issues, i.e., low ionic conductivity, poor sinter ability and interfacial incompatibility with electrodes. Therefore, the objective of this thesis is to optimize the ionic conductivity, understand the sintering mechanism of LLZO and enable solid garnet batteries. Specifically, dual substitution strategy is firstly adopted to optimize the ionic conductivity of LLZO. Afterwards, the microstructural and electrochemical properties, and the sintering mechanism of Al- and Ga-doped LLZO are studied in detail. Finally, solid garnet batteries are fabricated at room temperature with the incorporation of ionic liquids.