Lithium ion transport properties of high conductive tellurium substituted Li7La3Zr2O12 cubic lithium garnets

In this paper synthesis, structure and Li+ transport process of Li7−2xLa3Zr2−xTexO12 (x = 0.125 and 0.25) lithium garnets are reported. Preparation of high Li+ conductive Li7La3Zr2O12 (LLZ) in cubic phase by conventional solid state method demands sintering it around 1200 °C for 36 h in Al2O3 crucible. Cubic phase lithium garnet is successfully obtained at lower sintering temperature around 750 °C with the substitution of Zr4+ by Te6+ in the garnet lattice over the investigated composition range. Among the investigated compounds Li6.5La3Zr1.75Te0.25O12 sintered at 1100 °C exhibits a maximum room temperature total (bulk + grain boundary) ionic conductivity of 1.02 × 10−3 S cm−1. The present studies reveal the stabilization of the cubic garnet phase relatively at lower sintering temperature along with an enhancement in Li+ conductivity with lithium content lesser than 7 by suitable doping in Li7La3Zr2O12.