Process for producing lithium-containing composite oxide
To provide a process for a lithium-containing composite oxide for a positive electrode for a lithium secondary battery, which has a large volume capacity density and high safety, and is excellent in the charge and discharge cyclic durability and low temperature characteristics. A process for producing a lithium-containing composite oxide represented by the formula Li p N x M y O z F a (wherein N is at least one element selected from the group consisting of Co, Mn and Ni, M is at least one element selected from the group consisting of Al, alkaline earth metal elements and transition metal elements other than N, 0.9≦p≦1.2, 0.95≦x≦2.00, 0<y≦0.05, 1.9≦z≦4.2 and 0≦a≦0.05), which comprises firing a mixture of a lithium source, an N element source, an M element source and if necessary, a fluorine source, characterized in that an aqueous solution having an M element source dissolved therein is mixed with an N element source powder or its pulverized product to form a slurry; if necessary after being pulverized, the slurry is dried for granulation to obtain a granulated product, which is mixed with a lithium source powder and if necessary, a fluorine source powder to obtain a mixture; and the mixture is fired at from 700 to 1,100° C. in an oxygen-containing atmosphere.
1. A process for producing a lithium-containing composite oxide represented by the formula Li p N x M y O z F a , wherein N is at least one element selected from the group consisting of Co, Mn and Ni, M is at least one element selected from the group consisting of Al, alkaline earth metal elements and transition metal elements other than N, 0.9≦p≦1.2, 0.95≦x≦2.00, 0≦y≦0.05, 1.9≦z≦4.2 and 0≦a≦0.05, which comprises firing a mixture of a lithium source, an N element source, an M element source and when a is greater than 0, a fluorine source, wherein a slurry is formed by mixing an aqueous solution having an M element source dissolved therein with (1) either an N element source powder or (2) a pulverized product of the N element source powder; optionally after being pulverized, the slurry is dried for granulation to obtain a granulated product, which is mixed with a lithium source powder and when a is greater than 0, a fluorine source powder to obtain a mixture; and the mixture is fired at from 700 to 1,100° C. in an oxygen-containing atmosphere,
wherein the aqueous solution having an M element source dissolved therein is an aqueous solution comprising a salt of a carboxylic acid which has at least one carboxyl group, and at least one hydroxyl group, at least one carbonyl group, or at least one hydroxyl group and one carbonyl group, and the slurry is dried for granulation by spray-drying.
2. The process according to claim 1 , wherein the N element source powder in the slurry before drying for granulation has an average particle size (D50) of from 0.1 to 3 μm, and the granulated product has an average particle size (D50) of from 5 to 25 μm.
3. The process according to claim 1 , wherein the M element source is an ammonium zirconium carbonate, an ammonium zirconium halide, or an ammonium zirconium carbonate and an ammonium zirconium halide.
4. The process according to claim 1 , wherein the aqueous solution having an M element source dissolved therein has a pH of from 2 to 12.
5. The process according to claim 1 , wherein the N element source is at least one member selected from the group consisting of cobalt hydroxide, cobalt oxyhydroxide, tricobalt tetroxide and cobalt carbonate.
6. The process according to claim 1 , wherein the N element source is at least one member selected from the group consisting of a nickel salt, a cobalt salt, a manganese salt, a nickel-cobalt coprecipitate, a nickel-manganese coprecipitate and a nickel-cobalt-manganese coprecipitate.
7. A positive electrode for a lithium secondary battery containing a lithium-containing composite oxide produced by the process as defined in claim 1 .
8. A lithium secondary battery comprising the positive electrode for a lithium secondary battery as defined in claim 7 .
9. The process according to claim 1 , wherein M comprises Al and Mg.
10. The process according to claim 1 , wherein M comprises Zr and Mg.
11. The process according to claim 1 , wherein M comprises Mg, Al and Zr.