JPH08124595A - Activating method for alkaline secondary battery - Google Patents

Abstract

PURPOSE: To provide an activating method increasing a degree of activating positive/negative electrodes by controlling a temperature in a vessel to a prescribed value during a charging process. CONSTITUTION: An alkaline secondary battery is formed by receiving a positive electrode 1, negative electrode 2, separator 4, etc., in a vessel 4. During a charging process for activating this battery, a temperature inside the vessel 4 is controlled to 0 to 40 deg.C. By this temperature control, increasing a heating value due to a temperature rise according to internal resistance is suppressed, and decreasing a degree of activating the positive/negative electrodes, caused by decreasing charging efficiency of the positive/negative electrode 1, 2 based on the temperature rise, is prevented so as to obtain an activating method for the alkaline secondary battery increasing a degree of activating the positive/ negative electrodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for activating an alkaline secondary battery having an improved charging process.

[0002]

2. Description of the Related Art A nickel-hydrogen secondary battery, which is an example of an alkaline secondary battery, is manufactured by interposing a separator between a positive electrode containing nickel oxide as an active material and a negative electrode containing a hydrogen storage alloy as an active material. It is manufactured by housing the prepared electrode group in a container, injecting an alkaline electrolyte into the container, and sealing the opening of the container. After charging the secondary battery assembled in this way, the positive electrode and the negative electrode are activated by carrying out one or more cycles of discharging.

As the above-mentioned charge / discharge cycle, for example, there is known a method of charging at a temperature of 20 ° C. with a current of 0.1 CmA for 15 hours and then discharging with a current of 1 CmA until the battery operating voltage becomes 1V. . In this method, the current of the charging process is set to 0.5 CmA or more to shorten the time of the charging process and improve the productivity of the secondary battery.

By the way, the capacity of the nickel-hydrogen secondary battery has been improved in response to the recent demand for high-performance and high-capacity batteries. As a result, the current flowing through the secondary battery in the charging step increases in proportion to this, and the heat generated by the internal resistance of the secondary battery increases accordingly, so that the temperature inside the container of the secondary battery increases. Rises. However, since the charging efficiency of the positive electrode and the negative electrode of the secondary battery decreases as the temperature in the container rises, the degree of activation of the positive electrode and the negative electrode decreases, There is a problem that the discharge capacity is reduced.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems, and an object thereof is to provide a method for activating an alkaline secondary battery in which the degree of activation of the positive electrode and the negative electrode is improved. Is.

[0006]

SUMMARY OF THE INVENTION The present invention is an alkaline secondary battery having a structure in which an electrode group made by interposing a separator between a positive electrode and a negative electrode and an alkaline electrolyte are housed in a container. The activation method of the alkaline secondary battery, wherein the temperature in the container is controlled at 0 ° C. to 40 ° C. during the charging step.

The temperature inside the container during the charging process is controlled within the above range for the following reasons. When the temperature is lower than 0 ° C., the temperature inside the container of the secondary battery becomes too low, and the activation efficiency of the positive electrode and the negative electrode decreases. On the other hand, if the temperature exceeds 40 ° C., the temperature inside the container of the secondary battery is too high, and the charging efficiency of the positive electrode and the negative electrode decreases. In order to further improve the activation efficiency of the positive electrode and the negative electrode, the temperature is 20 ° C. to 3 ° C.
More preferably, the temperature is 0 ° C.

The temperature inside the container can be controlled by blowing air into the container, reducing the charging current, or applying either or both to the secondary battery. It is preferable to start the reduction of the blowing air and the charging current when the temperature of the container reaches 30 ° C to 40 ° C.

The temperature of the gas blown to the container is 0 ° C.
A temperature of 40 ° C is desirable, and a more preferable temperature is 20
The temperature is 30 ° C to 30 ° C. Examples of the gas include air, argon gas, nitrogen and the like.

Activation of the alkaline secondary battery is carried out, for example, by the following method. First, the secondary battery is subjected to standing aging. Subsequently, charging is performed with a constant voltage of 1.3 V or less or with a current of 0.05 CmA to 0.1 CmA, and then with a current of 0.05 CmA to 1.2 CmA. In this charging process, the temperature of the container is 3
When the temperature reaches 0 ° C. to 40 ° C., air blowing to the container is started, or the charging current is reduced, or either one or both are performed to control the temperature in the container within the above range. At this time, it is desirable that the charging current be small within the range of 0.05 CmA or more. After that, the secondary battery is activated by discharging and performing one or more such charging / discharging cycles.

The alkaline secondary battery activated by the method of the present invention will be described in detail with reference to FIG. The positive electrode 1 is
It is spirally wound with a separator 3 made of a synthetic resin fiber non-woven fabric interposed between the negative electrode 2 and the negative electrode 2 and is housed in a bottomed cylindrical container 4. The negative electrode 2 is arranged on the outermost periphery of the prepared electrode group and is in electrical contact with the container 4. The alkaline electrolyte is contained in the container 4. A circular sealing plate 6 having a hole 5 in the center is arranged in the upper opening of the container 4. The ring-shaped insulating gasket 7 is arranged between the peripheral edge of the sealing plate 6 and the inner surface of the upper opening of the container 4, and the sealing plate is attached to the container 4 by caulking to reduce the diameter of the upper opening inward. 6 is airtightly fixed via the gasket 7. One end of the positive electrode lead 8 is connected to the positive electrode 1, and the other end is the sealing plate 6.
Is attached to the underside of. Hat-shaped positive terminal 9
Is mounted on the sealing plate 6 so as to cover the hole 5. The rubber safety valve 10 is arranged so as to close the hole 5 in the space surrounded by the sealing plate 4 and the positive electrode terminal 9.

The positive electrode 1 is manufactured by preparing a paste containing nickel hydroxide powder, a cobalt compound, and a binder, filling the current collector with the paste, drying it, and then roller pressing.

Examples of the cobalt compound include cobalt monoxide, dicobalt trioxide, cobalt hydroxide and the like. Examples of the binder include carboxymethyl cellulose, methyl cellulose, sodium polyacrylate, polytetrafluoroethylene and the like.

The current collector is, for example, a net-like, sponge-like or fibrous material made of an alkali-resistant material such as nickel, stainless steel or a resin plated with nickel.
Examples thereof include a metallic porous body having a felt shape.

For the negative electrode 2, for example, a conductive agent such as carbon black is added to hydrogen storage alloy powder, and the mixture is kneaded with a binder and water to prepare a paste, and the paste is filled in a current collector and dried. After that, it is manufactured by molding. Examples of the binder and the current collector may be the same as those of the positive electrode 1. Further, as the negative electrode 2, one prepared by filling the current collector with a paste containing a powder of a cadmium compound in place of the hydrogen storage alloy powder can be used.

As the alkaline electrolyte, for example, a mixed solution of potassium hydroxide, sodium hydroxide and lithium hydroxide, a mixed solution of potassium hydroxide and lithium hydroxide and the like can be used.

[0017]

According to the method for activating an alkaline secondary battery of the present invention, during the charging process, the temperature in the container of the secondary battery is 0 ° C to
By controlling the temperature to 40 ° C., the activation efficiency of the positive electrode and the negative electrode of the secondary battery can be improved, so that the discharge capacity of the secondary battery can be improved. Further, by blowing air into the container during the charging process, the temperature inside the container can be controlled more easily.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. Examples 1 to 8 First, 10 parts by weight of cobalt monoxide as a conductive agent was added to 90 parts by weight of nickel hydroxide powder, and 0.3% by weight of carboxymethyl cellulose as a binder and 0.175 of sodium polyacrylate were added to this mixture. %, Polytetrafluoroethylene 0.5% by weight and water 45% by weight were added and kneaded to prepare a paste. A nickel fiber substrate was filled with the paste, dried, and molded to prepare a positive electrode.

On the other hand, LmNi _4.0 Co _0.4 Mn _0.3 Al
100 parts by weight of hydrogen storage alloy powder having a composition of _0.3 ,
0.5 parts by weight of polyacrylate, 0.125 parts by weight of carboxymethyl cellulose, 1.5 parts by weight of polytetrafluoroethylene, 1.0 part by weight of carbon and 50 parts by weight of pure water were kneaded to prepare a paste. The paste was applied to a nickel net serving as a current collector, dried, and roller pressed to produce a negative electrode.

Next, a separator made of, for example, a non-woven fabric made of polyolefin fiber, which has been subjected to hydrophilic treatment, is interposed between the positive electrode and the negative electrode and wound in a spiral to form an electrode group. This electrode group is, for example, 7N KOH and 1N Li
A container with a bottomed cylindrical container together with an alkaline electrolyte consisting of OH and having the structure shown in FIG.
A 4 / 5A type cylindrical nickel-hydrogen secondary battery was assembled with Ah.

25 ° C. for 100 obtained secondary batteries
After leaving it to stand for aging, it was stored in a 30 cm square tray so that 10 trays in each length and width. 1. While measuring the temperature of the side surface of the container of the secondary battery, at a temperature of 25 ° C.
After charging at a constant voltage of 2 V for 8 hours, charging was performed at a constant current of 1 CmA for 80 minutes. In this constant current charging, when the temperature of the side surface of the container reaches 30 ° C., air is blown to the side surface of the container under the conditions shown in Table 1 below, or constant current charging with a reduced charging current is performed. Did one or both. Then, the secondary battery was discharged with a current of 1 CmA until the battery operating voltage became 1V. Comparative Example 1 100 secondary batteries having the same configuration as in Examples 1 to 8 were activated under the same conditions as in Examples 1 to 8 except that the temperature control was not performed during the charging process.

Examples 1 to 8 thus activated
Also, the maximum temperature during charging was obtained for each of the secondary batteries of Comparative Example 1, and the maximum value and the minimum value thereof are shown in Table 1 below.
Also described in. In addition, the initial capacities of the secondary battery having the highest maximum temperature during charging and the secondary battery having the lowest maximum temperature were measured. In the secondary battery of Comparative Example 1, although the maximum temperature during charging was the smallest, the initial capacity was set to 1.00, and the initial capacity ratio was determined based on this, and the results are also shown in Table 1 below.

[0023]

[Table 1]

As is clear from Table 1, the secondary batteries of Examples 1 to 8 which were activated during the charging process to control the temperature in the container to 0 ° C to 40 ° C had a high initial capacity, Moreover, it can be seen that the variation is small. On the other hand, in the secondary battery of Comparative Example 1 that was activated without performing temperature control during the charging process, the temperature in the container during the charging process was 35 ° C to 82 ° C.
It can be seen that the initial capacity varies as well.

[0025]

As described in detail above, according to the method for activating an alkaline secondary battery of the present invention, the degree of activation of the alkaline secondary battery can be improved and the discharge capacity can be improved. Has a remarkable effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing an alkaline secondary battery activated by the method of the present invention.

[Explanation of symbols]

1 ... Positive electrode, 2 ... Negative electrode, 3 ... Separator, 4 ... Container, 6 ...
Seal plate.

Claims (2)

[Claims] 1. A method of activating an alkaline secondary battery, which has a structure in which an electrode group made by interposing a separator between a positive electrode and a negative electrode and an alkaline electrolyte are housed in a container. In the method for activating an alkaline secondary battery, the temperature in the container is controlled to 0 ° C to 40 ° C. 2. The method for activating an alkaline secondary battery according to claim 1, wherein the temperature inside the container is controlled by blowing air into the container.