PREPARATION BY A CHIMIE DOUCE ROUTE AND CHARACTERIZATION OF 5-LESS-THAN-OR-EQUAL-TO-Z-LESS-THAN-OR-EQUAL-TO-1) CATHODE MATERIALS

LiNi(x)Mn(1-x)ZO(2) cathode materials have been prepared using a 'chim ie 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 cl assical powder mixing and heating methods used generally, and material s with 0.5 less than or equal to z less than or equal to 1 are obtaine d easily. DTA-TG and XRD studies hive been performed for each composit ion. The LiNixMn1-zO2 crystallinity deteriorates progressively when th e manganese content is increased, but in contrast to the pure LiNiO2 c ompound, partial manganese substitution removes the lithium deficiency , Moreover, owing to the ease of oxidation of manganese ions, partiall y substituted compounds can be obtained at lower temperature than for pure LiNiO,. However, manganese substitution in LiNiO2 deteriorates th e 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 betw een layers when the Mn content is increased.