Excellent electrochemical response of Ce stabilized cubic Li7La3Zr2O12

Garnet-based Li7La3Zr2O12 is a promising solid-state electrolyte for lithium (Li) metal batteries owing to its broad electrochemical window and fantastic stability against Li anode. However, pure Li7La3Zr2O12 crystallizes in a tetragonal phase resulting in poor Li-ion conductivity. In this study, the conductive cubic phase was successfully stabilized by substituting Zr4+ (0.72 & Aring;) with a like-valent and larger-sized Ce4+ (0.87 & Aring;) using a ball-milling and a two-step sintering process. The resulting compound, Li7La3Zr1.75Ce0.25O12, exhibited significantly enhanced Li-ion conductivity (similar to 2.2 x 10(-4) S cm(-1)), one order of magnitude higher than the un-doped sample (similar to 2.3 x 10(-5) S cm(-1)), with negligible electronic conduction (similar to 10(-11) S cm(-1)). Consequently, symmetric cell Li| Li7La3Zr1.75Ce0.25O12|Li demonstrated remarkable cycling performance, maintaining stable polarization over 600 h at 25 degrees C and a current density of 70 mu A cm(-2). Thus, Ce-doped Li7La3Zr2O12 emerges as an innovative solid electrolyte for the next generation all-solid-state Li metal batteries.