Grain boundary resistance of fast lithium ion conductors: Comparison between a lithium-ion conductive Li-Al-Ti-P-O-type glass ceramic and a Li(1.5)A(10.5)Ge(1.5)P(3)O(12) ceramic

The structure and ionic conductivity of a lithium-ion conductive Li-Al-Ti-P-O-type glass ceramic (LATP) was studied by means of powder X-ray diffraction, transmission electron microscopy, and broadband impedance spectroscopy. The results were compared to a Li1.5Al0.5Ge1.5P3O12 (LAGP) ceramic. While the grain conductivity of LATP is higher than that of LAGP, the total conductivity of LATP is lower due to a large grain boundary resistance. The grain boundary resistance of LATP is characterized by a slightly higher activation energy and a slightly higher pre-exponential factor than the grain resistance. Our results indicate that the origin of the grain boundary resistance in these fast lithium ion conductors is clearly distinct from oxide ion conductors. (C) 2011 Elsevier B.V. All rights reserved.