253: Effect of Ti on ionic conductivity in Al and Ga substituted high entropy lithium garnet

Abstract: High-entropy garnet electrolytes are promising solid-state lithium conductors due to their thermal robustness, yet their ionic transport is highly sensitive to Li-site chemistry and dopant-induced defect formation. In this work, we investigate the effect of Ti content as well as Al and Ga substation Li6+xLa3Zr1Hf0.2TiyTa1-yO12 (y = 0.2 and 0.4) high-entropy Li-garnet to establish conductivity trends as a function of dopant type and Li content. Across both compositional sets, Ga substitution results in the lowest ionic conductivity (3.17- 4.22 ×10-5 S/cm), whereas Al substitution increases conductivity to 1.63 × 10-4- 2.23 × 10-4 S/cm. The Li-rich undoped compositions show the highest conductivities, reaching 3.43 × 10-4 S/cm. Overall, the results indicate that (1) the inclusion of Ti can improve conductivity, (2) Al substitution and Li excess more effectively promote Li-ion migration, (3) Ga likely improves structural stability at the expense of Li-ion mobility. These findings identify dopant selection and Li stoichiometry as key design parameters for optimizing transport in high-entropy garnet solid electrolytes.