Structural Change Induced by Electrochemical Lithium Insertion in Cobalt Vanadium Oxide

Abstract

We investigated the open-circuit potentials (OCPs) and structure of in the first discharge and charge processes. The OCPs in the discharge and charge processes traced different routes. In the discharge process, the OCPs declined slowly at and reduced more slowly at . From the change in the cell parameters, lithium was found to be intercalated in the tunnel space of at low lithium contents. Further lithium insertion induced an amorphous material and a crystalline one. The generation reaction of these substances containing lithium ions resulted in an irreversible capacity in the first cycle. Considering that the observed OCPs were distributed over a wide range of potentials in the charge process, it was probable that lithium was extracted dominantly from the newly generated amorphous substance. We concluded that the amorphous substance exhibited a reversible discharge-charge cycle performance after the second cycle.