| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To efficiently recover and produce cobalt sulfate from a positive electrode active material for a lithium ion secondary battery or the like. <P>SOLUTION: A lithium cobaltate-containing substance is dissolved with sulfuric acid diluted in the weight ratio of 1.47-1.67 of sulfuric acid to 0.67 to 4.0 of water to 1 of lithium cobaltate, and the dissolution solution is held at≥60°C till the completion of the dissolution. Hydrogen peroxide is added to the dissolution solution, and the electric potential of the dissolution solution is held to 0.4 to 0.8 volts. As a result, the reaction between the sulfuric acid and lithium cobaltate is progressed. Further, sulfuric acid is added to the dissolution solution, and the pH of the dissolution solution is held at 0.4 to 0.8. Then, the dissolution solution is cooled to≤30°C to crystallize cobalt sulfate. Thereafter, cobalt is recovered from the cobalt sulfate. Namely, in the dissolution of the lithium cobaltate, by using the hydrogen peroxide as a reducing agent, the electric potential of the dissolution solution is lowered without performing the mixing of metal salts, and the reaction between the sulfuric acid and lithium cobaltate is promoted. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
