Space-Charge-Mediated Superionic Transport in Lithium Ion Conducting Glass-Ceramics

This paper describes an investigation of the properties of superionic glass-ceramic specimens synthesized from the lithium aluminum-germanium-phosphate system. The specimens were characterized using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and impedance spectroscopy. The concentration of lithium oxide in the glass-ceramic formulations was the primary variable investigated. It is shown that the ionic conductivity of the specimens was dependent on the lithium oxide concentration. An optimized composition exhibited a conductivity approaching 10(-2) S cm(-1) at around room temperature. The superionic conductivity in these specimens is attributed to the space-charge-mediated effect resulting from the presence of the dielectric Li2O phase. The specimens also displayed different conductivities during heating and cooling scans, referred to in this paper as hysteresis effect. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3122903] All rights reserved.