Fabrication and Characterization of Fine-Grained Nasicon-Structured Li Electrolyte for Solid State Batteries Applications

Abstract

Rechargeable batteries using inorganic ionic conductors as solid electrolytes have been proposed over decades. Due to their improved safety features, solid state batteries have received great attention recently. Among several inorganic ionic conductors, NASICON-structured Li1+xAlxTi2-x(PO4)3 (LATP) show excellent ionic conduction and adequate structural stability when used as the solid electrolyte for Li battery applications. However, the physical properties of solid electrolyte may be affected by their chemical composition and processing parameters. Thus, the objective of this study is (i) to investigate the effect of grain size on the electrical properties, (ii) to lower interface polarization of layered oxide cathode/electrolyte, (iii) to examine the effect of microstructure variation on cathode/solid electrolyte performance. In this study, the ceramic self-standing thick films of Li- NASICON with composition Li1.3Ti1.7Al0.3(PO4)3 by tape casting were prepared. A full cell using layered oxide/graphite (or Li metal) as the cathode/anode separated by LATP were assembled and tested A complete characterization of the samples including structural, microstructural, impedance as well as the electrochemical testing were conducted. Due to dependence of grain-size on ionic conduction, more discussion will focus on the contribution of both the grain boundary and the "bulk" conductivity. Microstructure will be varied by creation of different pore size and porosity in order to search for better electrode configuration.