Preparation and characteristics of (NayAg1−y)2V4O11 for lithium secondary battery cathodes

Abstract Layered vanadium oxides, (Na y Ag 1− y ) 2 V 4 O 11 ( y =0.77–0.98) are prepared by substituting part of the silver ions in Ag 2 V 4 O 11 with sodium ions using an ion-exchange reaction in molten nitrate salts. These oxides exhibit less capacity loss during repeated cycling than non-substituted oxide, Ag 2 V 4 O 11 . This is mainly because the structural change into an amorphous state upon lithiation is restricted by the pillar effect in which unextractable sodium ions connect adjacent layers during lithium insertion/extraction.