Methods of preparing cathode active materials for lithium secondary

Abstract

The Li.sub.x Mn.sub.2 O.sub.4 powder for cathode active material of a lithium secondary battery of the present invention is prepared by a method of comprising the steps of mixing an acetate aqueous solution using Li acetate and Mn acetate as metal precursors, and a chelating agent aqueous solution using PVB, GA, PAA or GC as a chelating agent; heating the mixed solution at 70.about.90.degree. C. to form a sol; further heating the sol at 70.about.90.degree. C. to form a gel precursor; calcining the produced gel precursor at 200 .about.900.degree. C. for 5.about.30 hours under atmosphere. The cathode active material, Li.sub.x Mn.sub.2 O.sub.4 powder for a lithium secondary battery in accordance with the present invention has a uniform particle size distribution, a high crystallinity and a pure spinel-phase, and a particle size, a specific surface area, a lattice of a cubic structure and the like can be controlled upon the preparing conditions. The present invention also provides a method of preparing LiNi.sub.1-x Co.sub.x O.sub.2 powder, which comprises the steps of providing a gel precursor using PAA as a chelating agent and hydroxide, nitrate or acetate of Li, Co and Ni as metal precursors; heating the gel precursor at 200.about.900.degree. C. for 5.about.30 hours to form a powder. The Li.sub.x Mn.sub.2 O.sub.4 and LiNi.sub.1-x Co.sub.x O.sub.2 powder of the present invention can be used for a cathode active material of a lithium secondary battery such as a lithium ion battery or lithium polymer battery.