Positive electrode active material for nonaqueous secondary cells and a

Abstract

The mixed powders of a lithium compound and a transition metal based compound are formed into shaped parts, which are packed to form a bed 6 on a porous plate 5 in the bottom of a reaction vessel 7 placed on a support 10 in a firing furnace 8 equipped with an electric heater; the packed parts are fired with an oxidizing gas such as air being forced through the bed 6 at a superficial velocity higher than a specified value via a gas feed pipe 3 connecting an air pump 1, a flow regulator 2 and a preheater 4 and the gas emerging from the bed 6 is discharged into the air atmosphere through a ventilation port 9. Even if increased amounts of the mixed powders have to be fired, the invention process enables the production of a lithium complex oxide as an active material that is homogeneous and which features excellent cell characteristics. If the manufacturing conditions are controlled such that the media diameter as a powder characteristic of the lithium complex oxide is within an appropriate range while, at the same time, the ratio of the median diameter to the specific surface area diameter is adjusted to lie within an appropriate range, one can produce an active material that has not only high initial capacity but also improved cycle characteristics.