The effect of Y doping on the bottleneck size, microstructure and ionic conductivity of Li6.4Fe0.2La3-xYxZr2O12 solid electrolytes

The potential of Li7La3Zr2O12 (LLZO) as a solid electrolyte material for all-solid-state batteries is widely recognized. The bottleneck size of Li ion migration and the microstructure greatly affect the ionic conductivity of LLZO. This study aims to examine the impact of Y doping on the crystal structure, microstructure, and ionic conductivity of Fe-modified LLZO ceramic. X-ray diffraction analysis reveals that Y doping shrinks the bottleneck size and lattice constant. SEM results demonstrate that the incorporation of Y not only suppresses the abnormal grain growth but also improves the densification of Fe modified LLZO ceramic. The optimal bottleneck size (1.8441 Å) and a dense microstructure (relative density of 94.02 %) Li6.4Fe0.2La2.925Y0.075Zr2O12 result in an ionic conductivity of 5.56 × 10−4 S/cm and an activation energy of 0.258 eV at 30 °C.