Study on the role of Li2O–Ga2O3-GeO2-Gd2O3 glass doped into Li7La3Zr2O12 solid-state electrolyte

In this study, Li2O–Ga2O3-GeO2-Gd2O3 (LGGG) glass is doped into Li7La3Zr2O12 (LLZO) ceramic in proportions of 1, 2, 3, 4, and 5 wt% by a conventional solid-state reaction method. The main crystalline phase that existed in this composite electrolyte is proved to be cubic phase LLZO by XRD patterns. With a dosage of 3 wt% LGGG glass, the composite electrolyte has the highest ionic conductivity of 3.26 × 10−4 S cm−1, a maximum relative density of about 96.79%, and minimum activation energy of 0.276 eV at room temperature. This work also verifies that doping the same amount of identified elements into LLZO ceramics in the form of glass can obtain higher ionic conductivity and relative density than in the form of oxides (2.40 × 10−4 S cm−1 and 92.03%). A symmetric cell composed of this electrolyte reveals a good cycling performance and low overpotential in a total of 230 cycles at a current density of 0.125 mA cm−2. These results confirm the potential of this LGGG-LLZO composite electrolyte for applicating in new generation all-solid-state lithium-ion batteries. •Li2O–Ga2O3-GeO2-Gd2O3 (LGGG) glass was doped into Li7La3Zr2O12 for the first time.•The LGGG-doped LLZO sample G3 exhibited the highest room-temperature ionic conductivity density of 3.26 × 10−4 S cm−1.•The LGGG-doped LLZO sample G3 exhibited the highest relative density of 96.79%.•The activation energy of LGGG-doped LLZO sample G3 was as low as 0.276 eV.•The LGGG-doped LLZO sample G3 exhibited a low electronic conductivity of 5.58 × 10−7 S cm−1.•The Li + ions transference numbers of sample G3 were calculated to be 0.875.•The symmetric cell composed of G3 had a critical current density as high as 0.5 mA cm−2.