MECHANISTIC STUDIES ON THE ELECTROCHEMICALLY LITHIATED SPINEL LICUVO4

The lithiation mechanism of the spinel LiCuVO4 was studied by X-ray diffraction, XPS, and electrochemical measurements using the lithium cell with the spinel cathode. The lithiation proceeded by the following steps: (1) in the multiphasic reaction for x < 1.5 in Li1+xCuVO4, the LiCuVO4 spinel transforms to a new phase, Li2.5Cu0.5VO4, and Cu metal; (2) in the monophasic electrochemical displacement reaction for 1.5 < x < 2.0, the copper ions extrude from Li2.5Cu0.5VO4 with lithium intercalation, which forms Li3VO4 and Cu metal; (3) in the intercalation reaction for 2.0 < x < 5.0, lithium ions intercalate into Li3VO4 with several reaction steps. The new phase, Li2.5Cu0.5VO4, lithiated reversibly with the electrochemical displacement between copper and lithium ions. © 1991.