Perovskite-Type Electrolyte for Ceramic Lithium Batteries: Enhanced Microstructure and Bulk Ionic Conductivity

Solid-state lithium batteries (SSLBs) have shown great potential in energy storage applications, having the potential to enhance energy densities, while providing superior safety compared to conventional liquid electrolyte-based lithium batteries. Perovskite-type LLTO electrolytes are a promising candidate for SSLBs, due to their excellent ionic conductivities with values in excess of 10-3 S cm-1 at room temperature. However, their application in SSLBs is hindered by catastrophic dendrite formation and unstable interfaces during cycling with Lithium metal. It is also difficult to formulate electrolytes with desirable mechanical properties and high bulk ionic conductivity. Herein, in order to understand the microstructure, bulk ionic conductivity and mechanical properties of the most studied LLTO (Li0.3La0.5TiO3), cold-press sintering was used to prepare pellets with different thicknesses using a mixture of coarse and fine LLTO powders: D50=~40μm, and D50=~1μm, respectively. This significantly enhanced the compactness and density achieved in the cold pressing stage. The sintered pellets showed a modified grain boundary pattern with an enhanced bulk ionic conductivity of 10-4-10-6 S cm-1 between 20˚C and 60˚C and a low activation energy of ~0.21eV. Symmetric cells and half-cells using the as-prepared pellets are currently being assembled for further electrochemical characterization.