New amorphous oxides as high capacity negative electrodes for lithium batteries: the Li_xMVO_4 (M = Ni, Co, Cd, Zn; 1 < x <= 8) series

摘要

The crystallized precursors LiMVO_4 (M = Co, Ni, Cd, Zn) are irreversibly transformed to lithiated amorphous oxides Li_xMVO_4 (x close to 8) during the first Li insertion in a lithium battery. Under low rate, these amorphous oxides cycle large amounts of Li per formula unit in the 0.02-3 V range (versus Li), with an average voltage in the order of 0.6 V for Li insertion and 1.4 V for Li extraction. In the case of Li_xNiVO_4 at first Li extraction, for example, △x= 6.6 and Q=980 Ah/kg (active material alone) or 900 Ah/kg (calculated with respect to the total mass: material + carbon black) or 4230 Ah/l (active material alone), more than 5.5 times the volumic capacity of graphite.