Influence of Li2O-B2O3 glass on ionic migration and interfacial properties of La2/3-xLi3xTiO3 solid electrolyte

This work is devoted to coating perovskite-type La(2/3-x)Lia(x)TiO(3) (LLTO) grains with a Li2O-B2O3 (LIB) glass, considering good wetting properties, low melting point, and no grain boundary of LIB, to obtain novel LLTO/LIB composite electrolytes used for all-solid-state batteries. Perspectives with regard to the effect of LIB glass on mitigating the LLTO-related issues, such as low grain boundary conductivity, have been illustrated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and other techniques. From the characterization observations, the LLTO/LIB composites with the LIB phase filling at grain boundaries of LLTO show great densification, local lattice distortion and Li-ion redistribution. Obvious improvement on conduction properties both along LLTO grains and across LLTO electrolyte/LiCoO2 (LCO) electrode interface occurs by using appropriate amount of LIB materials. Specifically, LLTO/1.5 w06 LIB composite electrolytes achieve a grain boundary conductivity of 1.06 x 10(-4) S/cm at room temperature, which is more than one order of magnitude higher than that for pure LLTO. The favorable conduction behaviors have been also discussed on the basis of microstructure and Li-ion distribution of the composites, as well as intrinsic attributes of LIB glass, such as isotropic homogeneity and existence of non-bridging oxygens. (C) 2017 Elsevier B.V. All rights reserved.