Synthesis and Ionic Conductivity Studies of In- and Y-Doped Li6Hf2O7 as Solid-State Electrolyte for All-Solid State Li-Ion Batteries

The development of all solid-state lithium batteries is reliant on suitable high performance solid state electrolytes. Here, we present the synthesis and ionic conductivity of the In- and Y-doped Li6Hf2O7 materials; Li6+xHf2-xMxO7 (M = In3+, Y3+). Microwave-assisted synthesis was used to give phase pure material after heating for 4 hours at 850°C. The ionic conductivity of the materials is increased with the insertion of interstitial lithium ion within the structure from 0.02 to 0.25 mS cm−1 at 174°C and the activation energy for ionic conduction is lowered from 0.97(4) eV to 0.42(3) eV with respect to the undoped material.