Process of precipitation for spheric manganese carbonate and the products produced thereby
View Patent ↗Disclosed herein are a manganese carbonate useful as a material for spinel-type LiMn 2 O 4 , having a spherical morphology, and a method of preparing the same. The spheric manganese carbonate has a high packing density and shows superior lifetime characteristics, leading to spinel-type LiMn 2 O 4 resistant to structural changes and having superior lifetime characteristics.
1. 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.
2. The method as set forth in claim 1 , wherein the metal salt solution of step b) has a concentration from 0.5 to 3 M.
3. The method as set forth in claim 1 , wherein the carbonate solution of step c) has a concentration from 1 to 3 M.
4. The method as set forth in any one of claims 1 or 2 , wherein the coprecipitation reaction is conducted at a pH from 6.5 to 8.
5. The method as set forth in claim 1 , wherein the carbonate salt of step c) is selected from among ammonium hydrogen carbonate, sodium carbonate, ammonium carbonate and sodium hydrogen carbonate.