Lesson Learned from NMR: Characterization and Ionic Conductivity of LGPS-like Li7SiPS8

Harm, Sascha; Hatz, Anna-Katharina; Moudrakovski, Igor; Eger, Roland; Kuhn, Alexander; Hoch, Constantin and Lotsch, Bettina V. (2019): Lesson Learned from NMR: Characterization and Ionic Conductivity of LGPS-like Li7SiPS8. In: Chemistry of Materials, Vol. 31, No. 4: pp. 1280-1288

Abstract

We report on the facile solid-state synthesis and characterization of Li7SiPS8, a new member of the tetragonal Li10GeP2S12 (LGPS)-type family of ultrafast Li+ solid electrolytes. We analyze the structure, phase stability, and Li+ conductivity of tetragonal and orthorhombic LSiPS by pulsed field gradient NMR and impedance spectroscopy, which show conductivities at room temperature of up to 2 mS cm(-1). Although ranking tetragonal LiSiPS as an ultrafast solid electrolyte, the observed conductivity is unexpectedly low compared to other members of this solid-solution system. Utilizing solid-state NMR, quantitative phase analysis, and impedance spectroscopy, we identify an amorphous thiophosphate side phase with low Si content, which limits the intergrain conductivity and, hence, a potentially higher total conductivity. This case study thus highlights the need for comprehensive structural analysis of LGPS-type materials beyond the crystalline fractions to fully characterize the structure-property relationships in these glass-ceramic compounds.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Subjects: 500 Science > 540 Chemistry
• ISSN: 0897-4756
• Language: English