KR19980059081A - Anode Active Material Composition of Nickel-Metal Hydride Battery and Manufacturing Method Thereof - Google Patents

Abstract

By using the positive electrode active material composition of the nickel-metal hydride battery containing cobaltoxy hydride, cobalt compound, and nickel hydroxide, a battery having a negative electrode capacity smaller than that of a conventional battery can be manufactured. Can be prepared.

Description

Positive Electrode Active Material Composition of Nickel-Metal Hydride Battery and Manufacturing Method Thereof

[Industrial use]

The present invention relates to a positive electrode active material composition of a nickel-metal hydride battery, and more particularly, to a positive electrode active material composition of a nickel-metal hydride battery capable of greatly increasing the capacity of a battery, and a method of manufacturing a positive electrode using the same.

[Prior art]

Recently, with the trend toward miniaturization and lightening of new portable electronic devices such as camera-integrated VTRs, audio, laptop personal computers, portable telephones, and the like, there is a need for a technology for increasing the performance and capacity of batteries used as power sources for these devices. In particular, efforts are being made to develop technologies that reduce manufacturing costs of these batteries, particularly in economic terms. In general, batteries include primary batteries used for single use, such as manganese batteries, alkaline batteries, mercury batteries, and silver oxide batteries, Ni-MH (nickel-metal hydride) batteries using lead-acid batteries, and metal hydrides as negative active materials, and sealed nickel. Rechargeable batteries such as cadmium batteries, lithium-metal batteries, lithium-ion batteries (LIB: Lithium Ion Battery), lithium-ion batteries such as Lithium Polymer Battery (LPB), and the like; It can be divided into fuel cell, solar cell and the like.

Among them, primary batteries have a small capacity, short lifespan, and cannot be recycled, causing environmental pollution. On the other hand, secondary batteries can be recharged and used for a long time, and voltage is much higher than that of primary batteries. It is excellent in terms of efficiency and efficiency, and generates less waste, which is also excellent in environmental protection.

Among such secondary batteries, the cylindrical nickel-hydrogen battery uses hydrogen, which is clean energy, and is a type of secondary battery that is expected to play a role in the future as a secondary battery that is commercially available and commercially distributed.

The above-described nickel-hydrogen battery is a battery in which the negative electrode active material is a hydrogen storage alloy, the positive electrode active material is Ni (OH) ₂ , and an alkaline aqueous solution is used as the electrolyte, and is represented by Ni-MH (nickel-metal hydride). ) It is a battery. The electrochemical scheme of such a nickel-hydrogen battery is as follows.

In the above scheme, M represents a hydrogen storage alloy capable of absorbing and releasing hydrogen ions.

However, when the positive electrode of the nickel-hydrogen battery is manufactured using the positive electrode active material composition consisting of nickel hydroxide only, there is a problem that the conductivity of the positive electrode is poor. In order to solve this problem, a positive electrode active material composition in which cobalt (Co) or cobalt oxide (CoO) is added to a composition for manufacturing a positive electrode of a nickel-hydrogen battery is used. Thus, the positive electrode manufactured using the cobalt and cobalt oxide-added composition is electrochemically oxidized in the initial charging process of the battery and is converted into cobaltoxyhydride (CoOOH) on the nickel hydroxide surface, and these are present in the conductive properties of the positive electrode. This improves the utilization of nickel hydroxide, which is a cathode active material.

However, in the case of using the positive electrode to which the cobalt compound is added, hydrogen is generated in the negative electrode and accumulates in the negative electrode by the amount of charge generated by the conversion process of the cobalt compound. For this reason, when the battery is recharged, excess hydrogen is generated and reacts with the hydrogen storage alloy of the negative electrode due to the accumulated hydrogen, and the excess hydrogen is generated as hydrogen gas on the surface of the negative electrode. The generated hydrogen gas reacts with the oxygen gas generated from the nickel anode, causing a risk of explosion of the battery, and causing a rapid temperature rise inside the battery, thereby causing damage to electronic devices in which the battery is used. In order to solve this problem, a hydrogen storage capacity of the nickel-hydrogen battery negative electrode was designed to allow a margin, and a battery capable of preventing hydrogen gas generation at the negative electrode was manufactured and used. However, because the negatively designed negative electrode, which is excessively larger than the positive electrode, to increase the hydrogen storage capacity of the negative electrode of the battery, results in a smaller capacity of the positive electrode, which falls into a certain volume, the final designed battery has a problem that the capacity of the final battery is less than that of the original design. have.

The present invention is to solve the above problems, an object of the present invention is to provide a positive electrode active material composition of a nickel-hydrogen battery that can produce a battery of high capacity by reducing the negative electrode capacity while excellent in the conductivity of the positive electrode It is to provide a manufacturing method.

In order to achieve the above object, the present invention is cobalt oxyhydride; Cobalt compounds; A positive electrode active material composition and a cobalt compound of a nickel-hydrogen battery including nickel hydroxide are aged at room temperature in an aqueous alkali solution to obtain a cobaltoxyhydride compound; The cobaltoxyhydride compound is washed with deionized water and dried to obtain a cobaltoxyhydride powder.

In addition, the cobalt oxyhydride powder and cobalt oxide powder is mixed; It provides a method for producing a positive electrode active material composition of a nickel-hydrogen battery comprising the step of mixing the mixture with nickel hydroxide powder.

In the present invention described above, the cobalt compound is preferably selected from the group consisting of Co, CoO, CoOOH, Co ₂ O ₃ , Co ₃ O _4, Co (OH) ₂ .

In addition, in the present invention described above, the aqueous alkali solution is preferably 5% by weight KOH aqueous solution.

In the present invention, the aging step is preferably carried out for 24 hours.

EXAMPLE

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only one preferred embodiment of the present invention and the present invention is not limited to the following examples.

(Example 1)

Cobalt was aged in a 5% potassium hydroxide solution at room temperature for 24 hours to obtain a cobaltoxyhydride solution. The solution was analyzed by XRD to confirm that Co was converted to CoOOH. In order to remove potassium hydroxide from this cobalt oxyhydride solution, the resultant was washed with deionized water and dried in an oven at 60 ° C. to prepare cobalt oxyhydride powder.

(Example 2)

Cobaltoxyhydride powder was prepared in the same manner as in Example 1, except that cobalt oxide was used instead of cobalt.

(Example 3)

Cobalt oxyhydride powder and cobalt (Co) powder prepared according to the method of Example 1 was mixed, and then mixed with nickel hydroxide powder, to prepare a slurry.

(Example 4)

Cobalt oxyhydride powder and cobalt (CoO) powder prepared according to the method of Example 2 was mixed, and then mixed with nickel hydroxide powder to prepare a slurry.

(Comparative Example 1)

A slurry was prepared by mixing cobalt (Co) powder and nickel hydroxide powder.

(Comparative Example 2)

A slurry was prepared by mixing cobalt oxide (CoO) powder and nickel hydroxide powder.

As described above, when the battery is manufactured using the slurry of the present invention, the capacity ratio of the positive electrode and the negative electrode can be reduced by 20%, and the negative electrode capacity of the battery can be designed less than before, and as a result, the volume of the positive electrode This can increase the capacity of the final cell by 15%.

Claims (10)

A positive electrode active material composition of a nickel-hydrogen battery containing cobaltoxyhydride, a cobalt compound, and nickel hydroxide. The cathode active material composition of claim 1, wherein the cobalt compound is selected from the group consisting of Co, CoO, CoOOH, Co ₂ O ₃ , Co ₃ O _{4, and} Co (OH) ₂ . A method of producing cobalt oxyhydride, comprising the step of aging a cobalt compound in an aqueous alkali solution to obtain a cobalt oxyhydride compound and washing the cobalt oxyhydride compound with deionized water and drying to obtain a cobalt oxyhydride powder. The method of claim 3, wherein the aqueous alkali solution is a 5% by weight aqueous KOH solution. The method of claim 3, wherein the aging step is carried out for 24 hours. The method of claim 3, wherein the cobalt compound is selected from the group consisting of Co, CoO, CoOOH, Co ₂ O ₃ , Co ₃ O _4, Co (OH) ₂ . The cobalt compound is aged in a potassium hydroxide solution at room temperature to obtain a cobaltoxyhydride compound, and the cobaltoxyhydride compound is washed with deionized water and dried to obtain a cobaltoxyhydride powder, followed by the cobaltoxyhydride powder and cobalt oxide. A method of producing a positive electrode active material composition of a nickel-metal hydride battery comprising mixing a powder and mixing the mixture with a nickel hydroxide powder. The method of claim 7, wherein the cobalt compound is selected from the group consisting of Co, CoO, CoOOH, Co ₂ O ₃ , Co ₃ O _4, Co (OH) ₂ to prepare a positive electrode active material composition of a nickel-metal hydride battery Way. The method of claim 7, wherein the concentration of potassium hydroxide is 5%. The method of claim 7, wherein the aging step is performed for 24 hours.