Method for removing impurity element Na and S in precursor cobalt salts of cobaltosic oxide

Abstract

The invention relates to a method for removing impurity elements Na and S from the precursor cobalt salt of cobaltosic oxide. The method comprises the steps of adding proper a washing assistant in the process of washing cobalt salt with pure water so as to wash impurity ions Na, SO4<2 minus> contained in the cobalt salt and enable the impurity ions to enter waste washing water, thereby obtaining high purity precursor cobalt salt; calcinating to obtain the high purity cobaltosic oxide. The method has the advantages of simple operation, good impurity removing effect, and less cobalt loss. Both the weight ratio and the content ratio of Na and S to Co in the processed cobalt salt are lower than 1:15000, thereby ensuring the electrochemical activity and building a foundation for promoting the electrochemical properties of lithium cobalt oxide in lithium ion battery anode.

Description

technical field [0001] The invention relates to a method for removing sodium ions and sulfate ions in the preparation process of cobalt trioxide precursor cobalt salt, so as to obtain a pure cobalt salt intermediate, which is used to prepare tricobalt tetroxide as the positive core material of lithium batteries and other electronic materials. technical background [0002] Lithium-ion battery is a new kind of energy, which has many advantages such as high voltage, large capacity, safety and environmental protection, and has been widely accepted and used by people. Cobalt tetroxide is the core positive electrode material of lithium-ion batteries. It is mainly cobalt precursor cobalt salts such as cobalt carbonate or cobalt oxalate made from cobalt solution, and then processed by calcination to produce cobalt tetroxide. If there are more impurity elements in the precursor cobalt salt, especially Na and S, the electrochemical activity of tricobalt tetroxide will be reduced, whic...

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Problems solved by technology

[0004] Since the impurity elements Na and S are mostly Na + and SO 4 2- It exists in a water-soluble form. Therefore, the existing methods can only remove metal elements such as Fe, Cu, Ca, and Mg, but cannot effectively remove sodium and sulfur therein. Although when synthesizing the precursor cobalt salt, the cobalt salt Part of Na and S can be removed during the washing process, but as the amount of washing water increases, the hydrolysis and dissolution of cobalt salts intensify, and the loss of cobalt also increases, thereby increasing the treatment capacity of cobalt-containing wastewater

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