Effect of Nb Doping on Phase, Microstructure and Lithium-ion Conductivity of Li7La3Zr2O12 Solid Electrolyte

Abstract

Li 7 La 3 Zr 2 O 12 (LLZO) solid electrolyte with garnet structure is expected to become an important development direction of lithium-ion batteries in the future due to its large electrochemical window, good heat resistance and high safety. Since the lithium ions in c-LLZO are easier to diffuse than those in t-LLZO, the ionic conductivity of c-LLZO is two orders of magnitude higher than that of t-LLZO. Element doping is an important way to improve its ionic conductivity. Nb doping in LLZO stabilizes the cubic phase structure of LLZO by Zr doping, which will improve the ionic conductivity of LLZO at room temperature. Therefore, in this study, we studied the phase composition, microstructure and room temperature ionic conductivity of LLZO electrolyte doped with different contents of Nb by solid state reaction. Through comparative analysis, the electrolyte prepared by doping Y = 0.4 niobium element content has the best relative density (89.1 %) and room temperature ionic conductivity (2.05×10 -4 S cm -1 ).