Effects of excess lithium salt on properties of perovskite-type solid electrolyte Li_3/8Sr_7/16Ta_3/4Hf_1/4O₃

A new perovskite-type electrolyte "Li_3/8Sr_7/16Ta_3/4Hf_1/4O₃" (LSTH) was prepared by conventional solid-state reaction with different excess lithium carbonate (from 0 to 30 %). XRD, SEM, ICP-OES and AC impedance were used to determine the phase formation, microstructure, and room tempertature Li-ion conductivity. The results indicate that the impurity phase SrTa₂O₆ is significantly reduced, the density and room-temperature ionic conductivity of the LSTH pellet were improved with excess lithium salt. The LSTH pellets with 20 % excess lithium salt sintered at 1 300 ℃ for 10 h has a density of 6.56 g/cm³ and a room-temperature ionic conductivity to 3.12×10^-4 S/cm.