High Li ion conductivity in strontium doped Li7La3Zr2O12 garnet

• Pellets of strontium doped Li7 La3Zr2O12 with cubic garnet structure were processed through solid state reaction.
• 1.7 wt% Sr added LLZ displayed high ionic conductivity up to 4.95 × 10− 4 S/cm.
• 1.7 wt% Sr added LLZ displayed a low activation energy of 0.31 eV.
• Sr was substituted to La in the lattice and excess SrCO3 acted as a sintering agent.

Strontium doped lithium ion garnets Li7La3Zr2O12 (LLZ) with 0.9 wt% to 8.4 wt% content of added Sr were synthesized via conventional solid-state reaction. X-ray diffraction patterns confirmed the cubic garnet structure of the sintered samples. A small amount of strontium was substituted to lanthanum in LLZ lattice. Further analysis showed SrCO3 acted as a sintering aid for cubic LLZ ceramics and significantly increased the grain size of the sintered pellets. A conductivity of 2.10 × 10− 4 S/cm at 297 K was obtained for the undoped LLZ. The total ionic conductivity reached a maximum of about 5 × 10− 4 S/cm at 297 K with an activation energy of about 0.31 eV for 1.7 wt% Sr added LLZ sintered for 20–24 h in alumina crucible.