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

Abstract In this paper synthesis, structure and Li + transport process of Li 7−2 x La 3 Zr 2− x Te x O 12 ( x = 0.125 and 0.25) lithium garnets are reported. Preparation of high Li + conductive Li 7 La 3 Zr 2 O 12 (LLZ) in cubic phase by conventional solid state method demands sintering it around 1200 °C for 36 h in Al 2 O 3 crucible. Cubic phase lithium garnet is successfully obtained at lower sintering temperature around 750 °C with the substitution of Zr 4+ by Te 6+ in the garnet lattice over the investigated composition range. Among the investigated compounds Li 6.5 La 3 Zr 1.75 Te 0.25 O 12 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 Li 7 La 3 Zr 2 O 12 .