The influence of co-doping strontium and zirconium on structure and ionic conductivities of Li6+yLa3−ySryNbZrO12 solid electrolytes

Abstract

To enhance the ionic conductivity of lithium garnets, a co-doping strategy was adopted with both strontium and zirconium for [Formula: see text] ([Formula: see text], 0.25, 0.5, 0.75 and 1.0) (LLSNZO). By increasing the content of Sr, lithium garnet ceramics maintain cubic structure when [Formula: see text] is in the range of 0–0.75. A secondary phase of [Formula: see text] appeared in the ceramic when [Formula: see text]. We also studied the cross-section of lithium garnets with silver electrode. Results showed that the density of LLSNZO ceramics increased continuously against the increase of Sr content, while their total ionic conductivity enhanced initially and then reduced, with the maximum reached when [Formula: see text]. It is indicated that ionic conductivity of lithium garnets is not only decided by the density but also decided by the concentration and the mobility of [Formula: see text].