Preparation of particulate positive electrode material for lithium ion cells

A particulate positive electrode material for lithium ion cells is prepared by dispersing manganese(II) sulfate, iron(II) sulfate, and lithium phosphate and/or lithium hydrogenphosphate in water to form a slurry, effecting hydrothermal reaction in an autoclave to synthesize a lithium compound: LiMnFePOwherein x = 0.05 to 0.5 as primary particles, preparing a dispersion comprising the primary particles and an organic substance, spraying the dispersion, granulating, and drying to form aggregated particles having an average particle size of 0.5-4 µm, and firing the aggregated particles at 600-780°C for carbonizing the organic substance therein, yielding secondary particles having a reduced carbon content.