Transparent cubic garnet-type solid electrolyte of Al2O3-doped Li7La3Zr2O12

•Garnet-type solid electrolyte of HIP treated LLZ.•Bulk conductivity of 9.9 × 10− 4 S cm− 1 at room temperature.•Light transmittance is 30%.•Li/transparent LLZ/Li showed no short-circuit.

A transparent garnet-type lithium-ion conducting solid electrolyte of 1.0 wt% Al2O3-doped Li7La3Zr2O12 (A-LLZ) was prepared using hot isostatic pressing (HIP). The A-LLZ pellet sintered at 1180 °C for 36 h was followed by HIP treatment at 127 MPa and 1180 °C under an Ar atmosphere. The bulk conductivity of the HIP treated A-LLZ was 9.9 × 10− 4 S cm− 1 at 25 °C. The Li/HIP treated A-LLZ/Li cell showed no short-circuit due to lithium dendrite formation at 0.5 mA cm− 2.