Method for preparing lithium manganese oxide positive active material for lithium ion secondary battery, positive active material prepared thereby, and lithium ion secondary battery including the same
A method for preparing a lithium manganese oxide positive active material for a lithium ion secondary battery, which has spherical spinel-type lithium manganese oxide particles having two or more different types of sizes, the method including uniformly mixing manganese oxide having two or more different types of sizes with a lithium containing compound, and heat treating the resultant mixture to obtain lithium manganese oxide.
1. A method for preparing a lithium manganese oxide positive active material for a lithium ion secondary battery including spherical spinel-type lithium manganese oxide particles having two or more different sizes, the method comprising:
performing a pre-treatment process by dissolving manganese oxide in an acidic or basic solution and heat treating to obtain a first manganese oxide having particles of a first size;
mixing said first manganese oxide with a second manganese oxide having particles of a second size, different from said first size, to obtain a first mixture;
uniformly mixing said first mixture with a lithium containing compound to obtain a second mixture; and
heat treating said second mixture to obtain the lithium manganese oxide positive active material comprising a first lithium manganese oxide having particles of a third size, and a second lithium manganese oxide having particles of a forth size, different from said third size.
2. The method of claim 1 , wherein a particle size ratio of the first lithium manganese oxide to the second lithium manganese oxide is 1:0.2 to 1:0.4.
3. The method of claim 1 , wherein the first lithium manganese oxide and the second lithium manganese oxide are mixed in a ratio of 1:1 to 1:3 by weight.
4. The method of claim 1 , wherein the larger of said third size and said fourth size is in a range of 10 to 20 μm.
5. The method of claim 1 , wherein the acidic solution includes a sulfuric acid or hydrochloric acid solution, and the basic solution includes an ammonia or sodium hydroxide solution.
6. The method of claim 1 , wherein the heat treating in the pre-treatment process is performed at a temperature ranging from 300° to 600° C. for 4 to 6 hours.
7. A lithium manganese oxide positive active material for a lithium ion secondary battery, the positive active material prepared by the method claimed in any one of claims 1 to 4 , 5 and 6 .
8. A lithium ion secondary battery including the lithium manganese oxide positive active material prepared by the method claimed in any one of claims 1 to 4 , 5 and 6 , the lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator, and an organic electrolyte.