Preparation by a 'chimie douce' route and characterization of LiNizMn1-zO2(0.5<=z<=1) cathode materials

LiNi(x)Mn(1-x)ZO(2) cathode materials have been prepared using a 'chimie douce' route for 0.5 less than or equal to z less than or equal to 1. Coprecipitation of hydroxides is followed by drying and heating at 700 degrees C for 5 h under oxygen ow. Because of the high reactivity of the coprecipitates, the preparation time is shorter than for the classical powder mixing and heating methods used generally, and materials with 0.5 less than or equal to z less than or equal to 1 are obtained easily. DTA-TG and XRD studies hive been performed for each composition. The LiNixMn1-zO2 crystallinity deteriorates progressively when the manganese content is increased, but in contrast to the pure LiNiO2 compound, partial manganese substitution removes the lithium deficiency, Moreover, owing to the ease of oxidation of manganese ions, partially substituted compounds can be obtained at lower temperature than for pure LiNiO,. However, manganese substitution in LiNiO2 deteriorates the electrochemical capacity and reversibility of this compound. This is probably due to the large difference between the structures of nickel and manganese lithium oxides, which produces increasing disorder between layers when the Mn content is increased.