Sintering mechanism and greatly enhanced ionic conductivity of Mo-doped Li7La3Zr2O12 ceramics via a novel covered sintering

Due to the increasingly urgent safety and energy density concerns of lithium-ion batteries, more and more attention has been attracted by the Li 7 La 3 Zr 2 O 12 (LLZO)-based solid electrolytes with high ion conductivity and chemical stability against Li-metal. However, to prepare the high-quality LLZO ceramic electrolyte with high-ion conductivity and density, there is still a big challenge of the serious “Li-loss” and the abnormal grain growth during the long-time high-temperature sintering process. A novel covered sintering method is put forward to prepare the high-quality Mo-doped LLZO (LLZMO) ceramic electrolyte. The sintering strategy effectively suppresses the Li-loss to obtain the LLZMO dense ceramics with cubic garnet phase and tight grain boundaries. The LLZMO ceramics sintered at lower temperature of 1050 °C for 2 h via the novel covered sintering exhibit high density ( ρ r  = 92.3%) and high-ionic conductivity of 6.08 × 10 –4  S cm −1 at 25 °C, which are close to those of LLZO-based ceramics prepared by hot pressing sintering, ultrafast high-temperature sintering (UHS). The novel covered sintering provides an energy-saving, low-cost and high-efficient strategy to prepare the high-quality LLZO-based ceramics electrolyte.