Electrode properties of amorphous material of Li–Co–V–O system prepared by chemical lithium insertion in CoV 3O 8

Abstract

CoV 3O 8 exhibits a reversible discharge–charge after the second cycle, although it has an irreversible capacity in the first cycle. Our previous study proved that such reversible cycles were caused by an amorphous substance that was generated in the first discharge process. In this study, we attempted to synthesize the amorphous substance directly by means of the chemical lithiation of CoV 3O 8 and investigated its structure. n-Butyllithium reacted with CoV 3O 8 such that the Li/Co ratio became 2.76. Based on the change in the unit cell parameters, lithium intercalation was observed at a low lithium content. Further lithium insertion induced the formation of an amorphous and a crystalline material. Since these results were similar to those obtained in the case of electrochemical lithium insertion, we concluded that chemically lithiated CoV 3O 8 was the same as the electrochemically obtained sample. The samples were examined as an electrode material for a lithium-ion battery and exhibited a smaller irreversible capacity in the first cycle as compared to that of the original CoV 3O 8.