High lithium ionic conductivity in the garnet-type oxide Li_(7_x) La_3(Zr_(2_x), Nb_x)O_12(X=0-2)

摘要

Lithium garnet-type oxides Li_(7-x)La_3(Zr_(2-x). Nb_x)O_12 (X=0-2) were synthesized by a solid-state reaction, and their lithium ion conductivity was measured using an AC impedance method at temperatures ranging from 25 to 150℃ in air. The lithium ion conductivity increased with increasing Nb content, and reached a maximum of ~0.8 mS cm~(-1) at 25 ℃. By contrast, the activation energy reached a minimum of -~30 kj moH at the same point with X = 0.25. The potential window was examined by cyclic voltammetry (CV), which showed lithium deposition and dissolution peaks around OV vs. Li+/Li, but showed no evidence of other reactions up to 9 V vs. Li+/Li.