Low temperature synthesis of Al-doped Li7La3Zr2O12 solid electrolyte by a sol–gel process
Abstract Al-doped Li 7 La 3 Zr 2 O 12 (LLZ) was prepared by a sol–gel process using lithium nitrate, lanthanum nitrate hexahydrate, zirconium propoxide and aluminum tri-sec-butoxide as starting materials. Single phase of cubic LLZ was obtained by a heat treatment at 700 °C, which is lower than that in the solid state reaction process. The LLZ powders were sintered at 900 °C using LiBO 2 or Li 3 BO 3 to form composite solid electrolyte. In the composite sintered with LiBO 2 , La 2 Zr 2 O 7 was formed as an impurity phase. On the other hand, in the composite sintered with Li 3 BO 3 , single phase of cubic LLZ was obtained. The composite of Al-doped LLZ and Li 3 BO 3 sintered at 900 °C showed the total electrical conductivity of 1.9 × 10 − 5  S cm − 1 , while Al-doped LLZ pellet without additives showed 1.6 × 10 − 6  S cm − 1 .