KR19980059073A - Activation method of nickel-based secondary battery - Google Patents

Abstract

A part of the cobalt compound added as a conductive agent to the positive electrode of the nickel-based secondary battery is included in the negative electrode to increase the dissolution area of the cobalt compound in the battery, thereby increasing the solubility of the cobalt compound and the amount of the positive electrode active material, thereby increasing the capacity of the nickel hydride battery. And also to improve the porosity of the plate.

Description

Activation method of nickel-based secondary battery

[Industrial use]

The present invention relates to a nickel-based secondary battery, and more particularly, to include a portion of the cobalt compound added to the nickel positive electrode as a conductive agent in the negative electrode to increase the amount of the positive electrode active material to increase the capacity of the battery to increase the porosity of the electrode plate It also relates to an activation method of a nickel-based secondary battery to be improved.

[Private Technology]

As portable electronic devices such as cameras, camcorders, portable CD players, portable radio / recorders, laptops, computers, pagers, or mobile phones become more popular, batteries required for their operation require higher capacity and longer life. It is becoming.

Generally, a battery converts chemical energy into electrical energy by using a difference of contact potentials between suitable materials. The technical classification of the battery is that the primary battery is discharged only to convert chemical energy into electrical energy, the secondary battery can be repeatedly discharged and charged, and the fuel that converts combustion heat of hydrocarbons into electrical energy as it is. It can be classified into a battery and a solar cell that converts light energy into electrical energy. Moreover, according to the structure of electrolyte solution, it can classify into alkaline battery, solid electrolyte battery, non-aqueous solution battery, etc. According to the appearance of a battery, it can be classified into cylindrical battery, button type battery, and coin type battery.

Among them, secondary batteries can be repeatedly discharged and charged, have low temperature characteristics, easy to discharge large currents, and can be easily downsized. As a typical example of the secondary battery, a nickel cadmium battery of (-) Cd | KOH (LiOH) (aq) | NiOOH (+) is mentioned. In the nickel cadmium battery, a negative electrode is prepared by filling a cadmium into a porous body prepared by molding and sintering carbonyl nickel powder. After charging nickel hydroxide (Ni (OH) ₂ ) as a positive electrode and forming an electrode group together with a separator, which is an alkali polymer nonwoven fabric, a lithium hydroxide (LiOH) is included. Prepared potassium hydroxide (KOH) solution and prepared by closing the container.

The nickel cadmium battery produced by the above method has excellent low temperature characteristics and heavy load characteristics, and has a characteristic of long life due to charging and discharging. However, there is a critical disadvantage that the weight and volume are large, and the filling capacity is reduced by the memory effect and environmentally harmful due to the pollutant cadmium.

Other secondary batteries include nickel zinc batteries: (-) Zn | KOH (LiOH) (aq) | NiOOH (+), silver zinc batteries: (-) Zn | KOH (LiOH) (aq) | AgO (carbon) ( +) Or nickel iron battery: (-) Fe | KOH (LiOH) (aq) | NiOOH (+). These secondary batteries have a relatively large electrical capacity and excellent discharge characteristics, but have a disadvantage in that they take a lot of charging time and have a short lifespan.

Thus, a new type of battery has been developed called a nickel-metal hydride battery that uses a hydrogen storage alloy that is environmentally safe, compatible with nickel cadmium batteries, and has the same voltage and excellent electrical characteristics. Recently, attention has been focused on nickel hydride batteries having a charge capacity of 30 to 50% or more and using non-polluting hydrogen storage alloys as compared with conventional nickel cadmium batteries.

Ni-MH batteries use a negative electrode active material as a hydrogen storage alloy, a positive electrode active material as the same nickel hydroxide as a nickel cadmium battery, and an aqueous potassium hydroxide (KOH) solution as an electrolyte to decompose water in the electrolyte. It is a type of secondary battery that uses hydrogen storage alloy to store the generated hydrogen and discharges the necessary hydrogen into the electrolyte during discharge and charges and discharges. The terminal voltage is 1.2V and has the same voltage as the nickel cadmium battery. It has the advantage of being compatible, high in energy density and free from pollution. As the cathode material, LaNi ₅ , MmNi ₅ , Ti-Fe, or Ti-Ni alloys are used to store hydrogen generated during charging and to release stored hydrogen during discharge.

The electrochemical scheme of a nickel hydrogen battery is as follows.

In the above reaction formula, M represents a hydrogen storage alloy capable of absorbing and releasing hydrogen ions, and there are AB ₅ system using rare earth elements and AB ₂ system using Ti, Zr, V and the like. In the above formula, the positive electrode and the negative electrode of the nickel-metal hydride battery can be charged and discharged hundreds of times or more according to the above reaction formula.

On the other hand, in a nickel hydride battery, a cobalt additive is added to a nickel positive electrode to improve the conductivity of the positive electrode, thereby improving the utilization rate of nickel hydroxide as the positive electrode active material. Cobalt compounds added to the positive electrode include cobalt (Co), cobalt oxide (CoO), and cobalt hydroxide (Co (OH) ₂ ). These cobalt compounds are potassium hydroxide during the initial charging process of the battery. After dissolving in an aqueous solution of hydroxide, it undergoes an electrochemical oxidation process to convert cobaltoxy hydroxide (CoOOH) into the nickel hydroxide surface of the anode. However, when these cobalt compounds are dissolved in an alkaline electrolyte solution, the amount and the maturation time of a certain electrolyte solution injected into the battery are limited, and the dissolution area that can be in contact with the electrolyte solution is limited. All of these 100% is not converted and there is a problem that the battery utilization cannot be increased by the amount added. In addition, when the amount of the cobalt compound added to the positive electrode increases, the amount of nickel hydroxide of the positive electrode, which determines the capacity of the battery, is relatively decreased, thereby reducing the capacity of the battery.

The present invention has been made to solve the above problems of the prior art, an object of the present invention is to provide a nickel-based secondary battery with improved capacity of the battery by increasing the capacity of the battery positive electrode and at the same time improve the battery utilization have.

[Means for solving the problem]

In order to achieve the above object of the present invention, the present invention has the following configuration in the case of a nickel hydrogen battery.

In the present invention, it comprises a positive electrode plate, a negative electrode plate, an electrolyte, a positive electrode terminal, a negative electrode terminal, the electrode plate includes a support and an active material and / or a conductive agent applied to the support, the conductive agent is a conductive agent dissolved in the electrolyte In the battery, the capacity of reducing the amount of the conductive material of the one electrode plate of the electrode plate to increase the amount of active material of the electrode plate by the amount of the conductive agent decrease, and to increase the amount of the conductive agent to the other electrode plate by approximately the amount of conductive agent decrease of the electrode plate It provides an increased cell.

It is preferable that a positive electrode plate active material contains a nickel type compound.

The conductive agent is selected from the group consisting of cobalt, cobalt oxide and cobalt hydroxide, and the conductive agent is preferably mixed with 5 to 50% by weight with respect to the total amount of the conductive agent included in the conventional electrode plate.

And it is preferable that the negative electrode plate active material further contains a thickener and a binder.

[Action]

The present invention is to include a part or all of the cobalt compound added to the nickel anode to improve the conductivity in the negative electrode to impart conductivity to the positive electrode and the negative electrode through the aging process and after the charging and discharging process for the initial activation after fabricating the battery Increased solubility and utilization of cobalt compounds by increasing the dissolution area of cobalt compounds in the battery, thereby reducing the amount of cobalt compounds added to the positive electrode to increase the amount of nickel hydroxide as a positive electrode active material by a certain volume of the positive electrode As a result, the capacity of the battery can be increased. In addition, the added cobalt compounds contained in the negative electrode were eluted to secure additional pores in the electrode plate, thereby improving the porosity, thereby improving battery performance and consequently improving the utilization of the negative electrode.

The following presents a preferred embodiment of the present invention. However, the following examples are provided only to more easily understand the present invention, and the present invention is not limited to these examples.

EXAMPLE

Example 1

MmNi ₅ and Mm having an average particle diameter of 60 µm are all of the so-called mismetal-based alloy powders containing a predetermined amount of Al, Mn, Co, or Ni in an alloy composed mainly of about 50% Ce, about 30% La, and about 15% Nd. 1 wt% and 2 wt% of carbon black and PTFE (Polypron TFE) and 5 wt% of cobalt were mixed in the form of a slurry, and the slurry was coated on a plate nickel collector and dried. A nickel hydrogen negative electrode was prepared by the process described above.

Example 2

MmNi ₅ and Mm having an average particle diameter of 60 µm are all of the so-called mismetal-based alloy powders containing a predetermined amount of Al, Mn, Co or Ni in an alloy composed mainly of about 50% Ce, about 30% La, and about 15% Nd. 1 wt% and 2 wt% of carbon black and 10 wt% of cobalt oxide were mixed with a binder to prepare a slurry, and the slurry was coated on a plate-shaped nickel current collector and dried. To prepare a nickel hydrogen cathode.

Example 3

MmNi ₅ and Mm having an average particle diameter of 60 µm are all of the so-called mismetal-based alloy powders containing a predetermined amount of Al, Mn, Co or Ni in an alloy composed mainly of about 50% Ce, about 30% La, and about 15% Nd. 1 wt% and 2 wt% of carbon black and PTFE were mixed with a binder and 15 wt% of cobalt hydroxide to prepare a slurry, and the slurry was coated on a plate nickel collector and dried. The nickel hydrogen cathode was manufactured by the process.

Comparative example

Carbonyl nickel powder was molded and calcined to prepare a porous body, and MmNi ₅ and Mm having an average particle diameter of 60 μm were selected from Al, Mn, Co, or Ni in an alloy composed mainly of about 50% Ce, about 30% La, and about 15% Nd. 100 parts by weight of a so-called Mischmetal-based alloy powder containing a predetermined amount and 1% by weight and 2% by weight of carbon black and PTFE were mixed for the hydrogen storage alloy, respectively, to prepare a slurry, and the slurry was plate-shaped nickel current collector. Nickel hydrogen cathode was prepared by the process of coating on and drying.

Each electrode manufactured in the above Examples and Comparative Examples was used as a cathode, a porous body made by molding and sintering carbonyl nickel powder was filled with nickel oxyhydride as a cathode, an alkali resistant polymer as a separator, and thickened. A nickel hydride battery was produced according to a conventional secondary battery manufacturing method using potassium hydroxide as an electrolyte. The battery is initially activated at 3 cycles with 150% charge at 0.1C, 0.9V cut-off at 0.2C, and 200 times charge and discharge with 1C 150% charge and 1C 0.9V cut-off. It was repeated.

The battery characteristics were measured and shown in Table 1 below.

Including a part of the cobalt compound added to the positive electrode of the nickel-metal hydride battery in the negative electrode to increase the solubility of the cobalt compound in the battery, reduce the amount of cobalt compound added to the positive electrode and increase the amount of the positive electrode active material to increase the capacity of the battery It improves the porosity of the electrode plate and consequently improves the performance of the nickel metal hydride battery.

Claims (5)

In a battery comprising a positive electrode plate, a negative electrode plate, an electrolyte, a positive electrode terminal, a negative electrode terminal, the electrode plate includes a support and an active material and / or a conductive agent applied to the support, the conductive agent is a conductive agent dissolved in an electrolyte, wherein A battery having an increased capacity by reducing the amount of conductive material of the one electrode plate in the electrode plate to increase the amount of active material in the electrode plate by the amount of the conductive agent decrease, and increasing the amount of the conductive agent in the other electrode plate by approximately the amount of the conductive agent decrease in the electrode plate. The battery of claim 1, wherein the positive electrode plate active material comprises a nickel-based compound. The battery of claim 1, wherein the conductive agent is selected from the group consisting of cobalt, cobalt oxide, and cobalt hydroxide. The battery according to claim 1, wherein the conductive agent is mixed in an amount of 5 to 50% by weight with respect to the total amount of the conductive agent contained in the first electrode plate. The battery of claim 1, wherein the negative electrode active material further comprises a thickener and a binder.