Patent ID: 8211397

Claim:
A method for preparing spheric complex manganese carbonate for cathode active materials of a lithium secondary battery, the cathode active materials having a spinel crystal structure, the method comprising: a) mixing distilled water and an aqueous hydrazine (H 2 NNH 2 ) solution in a reactor, the aqueous hydrazine (H 2 NNH 2 ) solution being used in an amount from 0.5 to 4-vol % based on the total volume of the distilled water, b) feeding into the reactor a metal salt solution together with an aqueous ammonia solution having a concentration from 0.1 to 0.8 M., wherein the metal salt solution contains an Mn salt and a metal salt at a molar ratio represented by Mn 1-x M x , wherein M is a metal selected from the group consisting of Ni, Co, Mg, Zn, Ca, Sr, Cu, Zr, P, Fe, Al, Ga, In, Cr, Ge and Sn, and x is between 0.01 and 0.25 inclusive, and c) adding a mixture of a carbonate solution and a hydrazine solution to the reactor to cause a coprecipitation reaction.