Sr2+ and Mo6+ co-doped Li7La3Zr2O12 with superior ionic conductivity

Abstract Li7La3Zr2O12 (LLZO), a kind of solid-state electrolyte possessing the potential to realize an all-solid-state battery, attracts lots of attention. The Sr2+ and Mo6+ are co-doped into LLZO to obtain Li6.6+xLa3−xSrxZr1.8Mo0.2O12, in which x varies from 0 to 0.2. The strategy of doping Mo6+ into Zr4+-site can effectively ensure the formation of the cubic phase. On the basis of Zr4+-site doping method, doping appropriate Sr2+ can further improve the ionic conductivity and the relative density of the sample. A low temperature of 1100 °C and the cold pressing sintering method are applied. Through X-ray diffraction (XRD), Raman spectrum, inductively coupled plasma-optical emission spectroscopy (ICP-OES) and scanning electron microscope (SEM), we further discuss the mechanism of doping elements into lattice of LLZO. When x = 0.05, the sample Li6.65La2.95Sr0.05Zr1.8Mo0.2O12 exhibits the ionic conductivity of 6.43 × 10−4 S cm−1 (the highest among the works which used single Sr2+ or Mo6+ to dope LLZO) and the relative density of 95%.