Interfacial phenomena between lithium ion conductors and cathodes

Abstract

Nanocomposites of a lithium ion conductor Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 and electrode materials (TiO 2 and FePO 4 ) were prepared to investigate interfacial structure and ionic conductivity at the interface between the solid electrolyte and electrode materials. It was revealed that lithium ions in the solid electrolyte were attracted to the cathode materials with increasing electrode potential, which increases lithium vacancies in the solid electrolyte. For the FePO 4 containing composites, due to the high electrode potential, lithium transfer across the interface and ionic conduction through the cathode materials was remarkable. The results suggest that severe lithium depletion occurs and interfacial resistance is large at the interface of high ionic conductors and cathode materials. The space charge layer thickness is also discussed. • Nanocomposites of lithium ion conductors and electrode materials were fabricated. • Conductivity enhancement depended on charge carriers and cathode potentials. • High potential cathodes cause lithium depletion in high ionic conductors. • All the results were well explained with the space charge layer model.