Electrochemical properties of Li6+yLa3−yBayNbZrO12 lithium garnet oxide solid-state electrolytes with co-doping barium and zirconium

In this work, we co-doped barium (Ba) and zirconium (Zr) in a lithium garnet oxide , to improve its electrochemical properties . In the doping range of y = 0–1.0, the Li 6+y La 3−y Ba y NbZrO 12 (LLBNZO) oxides maintain a cubic crystal structure. A secondary phase of BaZrO 3 emerges when y ≥ 0.75. The ionic conductivity of the developed garnet oxides first increases with Ba-doping in the low doping range and then decreases in the high doping range. It reaches the maximum value in Li 6.5 La 2.5 Ba 0.5 NbZrO 12 when y = 0.5. Cyclic voltammetry shows that the garnet oxides have a wide electrochemical voltage window up to 6 V. The constant-current polarization results on the symmetric cells assembled from Li 6.5 La 2.5 Ba 0.5 NbZrO 12 reveal that this garnet oxide is chemically stable against metallic lithium and has stable cycling performance.