Reduced synthesis temperature and significantly enhanced ionic conductivity for Li6.1Ga0.3La3Zr2O12 electrolyte prepared with sintering aid CuO

Garnet-type Li7La3Zr2O12 (LLZO) is considered as a promising solid electrolyte. However, the synthesis of LLZO often requires a high temperature, which may lead to the evaporation of the lithium and result in a decrease in ionic conductivity. Therefore, it is an important issue how to reduce the synthesis temperature of LLZO and simultaneously increase its ionic conductivity. Herein, we synthesized garnet-type solid electrolytes of Li6.1Ga0.3La3Zr2O12 (LLZO-Ga) with x wt% CuO (x = 0, 0.2, 0.5, 1, 2) by the traditional solid-state reaction method, in which CuO was introduced as a sintering aid to reduce the sintering temperature of LLZO-Ga and increase its Li-ion conductivity. It is found that adding a small amount of CuO as an additive can reduce the sintering temperature from 1100 ℃ to about 1000 ℃. As a result, when the amount of CuO is 0.5 wt%, LLZO-Ga shows the highest room-temperature ionic conductivity and the lowest activation energy, which are 1.111 mS/cm and 0.27 eV, respectively.