JPH05283071A - Activation of metal hydride storage battery - Google Patents

Abstract

PURPOSE:To restrict the decrease of charge reserve (increase of discharge reserve) at the time of charge. CONSTITUTION:In the activation of sealed alkaline battery provided with nickel hydroxide positive electrodes 1, at least, which include metal cobalt or cobalt compound, and a negative electrode 2 using hydrogen storage alloy, after assembling a battery, the battery is charged with the high current so that the nickel hydroxide is charged immediately, and after finishing the charge with the high current, the battery is charged with the current lower than this high current.

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 a metal hydride storage battery using a hydrogen storage alloy electrode as a negative electrode.

[0002]

2. Description of the Related Art Generally, in a normal battery, the negative electrode capacity is
It is configured to be larger than the positive electrode capacity, thereby forming a charge reserve portion and a discharge reserve portion. Here, the charge reserve is an uncharged portion remaining in the negative electrode when the positive electrode is fully charged during charging. As described above, by providing the charge reserve, the oxygen gas can be preferentially generated from the positive electrode during charging, so that the hydrogen gas can be prevented from being generated from the negative electrode. Also, when the battery is repeatedly charged and discharged, the negative electrode deteriorates,
Since the charge reserve portion is charged in place of such a non-chargeable portion, there is an advantage that a decrease in charge amount can be prevented.

On the other hand, the above-mentioned discharge reserve is a charged portion which remains in the negative electrode when the positive electrode is completely discharged. For example, when the charge and discharge efficiency of the negative electrode is not so high as in a nickel-cadmium storage battery, the presence of the discharge reserve can prevent the battery capacity from being limited by the capacity of the negative electrode during discharging, and the battery capacity can be sufficiently increased. There is an advantage that it can be taken out.

The charge reserve and the discharge reserve have a relation that the discharge reserve increases when the charge reserve decreases, and conversely the discharge reserve decreases when the charge reserve increases.

In the nickel-cadmium storage battery, as described above, the charge / discharge efficiency of the negative electrode is not very high. Therefore,
In order to secure the discharge reserve in advance, an activation method has been proposed in which the battery is assembled and sealed, and then the first charge is performed with a low current (see Japanese Patent Laid-Open No. 64-21864). With such an activation method, the charging potential of the metallic cobalt or cobalt compound added to the positive electrode is lower than the oxidizing potential of nickel hydroxide, which is the active material of the positive electrode, during charging. Initially, metallic cobalt or cobalt compound is preferentially oxidized, and the start of charging nickel hydroxide is delayed. In the meantime, the cadmium electrode is charged to form metal cadmium for the discharge reserve. In addition, charging with a low current has a higher charging efficiency than charging with a high current, and the activation effect is high.

By the way, in recent years, as an alkaline storage battery which is lightweight, has a high capacity, and has a high energy density, a negative electrode made of a hydrogen storage alloy that electrochemically absorbs and releases hydrogen instead of the above-mentioned paste type cadmium electrode. Attention has been paid to a hydrogen storage alloy storage battery using a battery.

[0007]

However, since the hydrogen storage alloy storage battery itself is a new battery, the method for activating the storage battery is not established at present. Therefore, for example, a method of activating the storage battery by the low-current charging method used for the nickel-cadmium storage battery can be considered. However, this method has the following problems.

That is, the negative electrode using the hydrogen storage alloy has a high discharge efficiency and does not require much charge reserve. Moreover, the activation method in which a large amount of discharge reserve is generated is not preferable because the charge reserve is reduced and the cycle life is shortened. The present invention has been made in view of the above problems, and an object of the present invention is to suppress a decrease in the charge reserve (increase in the discharge reserve) during charging.

[0009]

In order to achieve the above object, activation of a sealed alkaline battery using a nickel hydroxide positive electrode plate containing at least metallic cobalt or a cobalt compound and a negative electrode plate using a hydrogen storage alloy. In the method, immediately after assembling the battery, the first step of charging the battery with a high current such that nickel hydroxide is charged, and after finishing the charging with the high current, charge the battery with a lower current. And a second step of performing.

[0010]

When the first charge is performed at a high current as in the above structure, the battery voltage immediately rises to a potential at which nickel hydroxide is oxidized. Therefore, unlike the above-mentioned low current charging method, oxidation of metallic cobalt or cobalt compound does not occur preferentially, and nickel hydroxide starts charging immediately. As a result, it is possible to prevent only the negative electrode active material from being charged prior to the positive electrode active material, and thus it is possible to prevent a decrease in the charge reserve (increase in the discharge reserve).

After that, even if the charging current is reduced and the battery is charged, the battery voltage does not become the battery voltage at which the metallic cobalt or the cobalt compound is oxidized. Therefore, metallic cobalt or the like is not charged preferentially over nickel hydroxide. As a result, charging can be performed at a low current, and an activation effect that is almost the same as that when charging is performed at a low current from the beginning can be obtained, and as a result, almost the same battery capacity can be obtained.

In addition, recent battery-using equipment is set to stop discharging when the battery voltage becomes lower than a certain value, so that the battery will not be completely discharged or over-discharged. Is becoming In such a state of use, even if repeated charge and discharge are repeated, the discharge ends at a voltage higher than the battery voltage at which the metal cobalt and cobalt compounds oxidize, and at the time of discharge, charging starts from this battery voltage. The compound is not preferentially oxidized. Therefore, similarly to the above, it is possible to prevent a decrease in the charge reserve (an increase in the discharge reserve).

[0013]

【Example】

[Embodiment] FIG. 1 is a cross-sectional view of a cylindrical sealed nickel-hydrogen storage battery according to an example of the present invention, in which a paste-type nickel positive electrode 1, a negative electrode 2 having a hydrogen storage alloy, and positive and negative electrodes 1 and 2 are interposed. Electrode group 4 consisting of inserted separator 3
Is wound in a spiral shape. The electrode group 4 is arranged in an outer can 6 that also serves as a negative electrode terminal, and the outer can 6 and the negative electrode 2 are connected by a negative electrode conductive tab 5. A sealing body 8 is attached to the upper opening of the outer can 6 via a packing 7, and a coil spring 9 is provided inside the sealing body 8. The coil spring 9 is configured to be pressed in the direction of arrow A when the internal pressure inside the battery is abnormally increased, and the gas inside is released into the atmosphere. Further, the sealing body 8 and the positive electrode 1 are connected by a conductive tab 10 also serving as a positive electrode.

Here, the cylindrical hermetic nickel-containing type having the above-mentioned structure
A hydrogen storage battery was manufactured as follows. Preparation of Positive Electrode An active material consisting of 94 parts of nickel hydroxide, 3 parts of metallic cobalt, and 3 parts of cobalt hydroxide and having an average particle diameter of 15 μm was mixed with a paste solution to prepare a paste. Next, this paste was filled in sponge-like nickel (average pore size 170 μm) as a base for holding the active material.

Next, the holding substrate after filling is dried to form an active material layer, a fluororesin dispersion is applied onto the active material layer, further dried and pressed, and then cut into a predetermined size. It was produced by. Manufacture of Negative Electrode Hydrogen absorbing alloy (MmNi ₅ type alloy) was pulverized into fine powder, 95 parts and 5 parts of fluororesin as a binder were added, and the mixture was uniformly mixed to form a fiber of the fluororesin. Made into Next, water was added to this fibrous material to prepare a paste, and the paste was pressed onto both surfaces of a nickel-plated punching metal current collector, and then cut into a predetermined size.

After that, the positive and negative electrode plates 1 and 2 produced as described above are wound around a separator 3 having alkali resistance to produce a spiral electrode group 4, and then the electrode group 4 is It was inserted into the outer can 6. Then, the electrolytic solution was injected into the outer can 6, and the outer can 6 was sealed with the sealing body 8 to produce a cylindrical sealed nickel-hydrogen storage battery having a nominal capacity of 1200 mAH.

After this, the cylindrical sealed nickel-hydrogen storage battery produced as described above was applied with a current of 1.0 C (1200 m).
A) for 10 minutes, 0.25C (300 mA) for 6 hours,
After initial charging, discharging was performed at 1.0 C to complete the initial activation. The battery that has been initially activated under the above conditions is hereinafter referred to as (a) battery. [Comparative Example] The same procedure as in the above Example except that the initial charging of the cylindrical sealed nickel-hydrogen storage battery produced in the same manner as in the Example was performed at 0.25 C for 7 hours. Initial activation was performed.

The battery which has been initially activated under the above-mentioned conditions is hereinafter referred to as (x) battery. [Experiment] The discharge characteristics and the battery capacity, the capacity of the negative electrode plate, the discharge reserve, and the charge reserve were measured using the battery (a) of the present invention and the battery (x) of the comparative example. The results are shown in Table 1. And shown in FIG.

The values in Table 1 are expressed as percentages with respect to the negative electrode capacity when the negative electrode capacity is 100. First, as is clear from FIG. 2, in the battery (a) of the present invention, a flat portion due to the oxidation of metallic cobalt and a cobalt compound is not recognized around the battery voltage of 0.9 V to 1.1 V. As a result, it can be confirmed that the positive electrode is being charged without delaying the charging of the negative electrode, so that the reduction of the charge reserve of the negative electrode can be suppressed.

[0020]

[Table 1]

Further, as is clear from Table 1, it was confirmed that the battery (a) of the present invention has a smaller discharge reserve and a larger charge reserve than the battery (x) of the comparative example. It is considered that this makes it possible to suppress a decrease in the cycle life of the battery. At the same time, it can be seen that the characteristics of the negative electrode hydrogen storage alloy with high charging efficiency are fully utilized.

Further, the battery capacity has almost the same value as that when the charging is performed at a low current, and the charging efficiency does not change even when the charging is performed at a high current at the beginning of charging from here. Can be confirmed.

[0023]

As described above, according to the present invention,
Since charging of nickel hydroxide is started and progressed without delay, it is possible to set an appropriate discharge reserve and charge reserve, and it is possible to effectively use the negative electrode having good discharge efficiency.

In addition, since charging is performed with a high current at the beginning of activation, the initial activation time is shortened. From these facts, there is an excellent effect that the battery performance can be dramatically improved while improving the workability.

[0025]

[Simple Drawing Description]

[0026]

FIG. 1 is a cross-sectional view of a cylindrical sealed nickel-hydrogen storage battery according to the present invention.

[0027]

FIG. 2 is a graph showing charge curves of the battery (a) of the present invention and the battery (x) of a comparative example.

[0028]

[Explanation of symbols]

 1 positive electrode 2 negative electrode

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[Procedure amendment]

[Submission date] November 16, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art Generally, in a normal battery, the negative electrode capacity is
It is configured to be larger than the positive electrode capacity, thereby forming a charge reserve portion and a discharge reserve portion. Here, the charge reserve is an uncharged portion remaining in the negative electrode when the positive electrode is fully charged during charging. As described above, by providing the charge reserve, it is possible to preferentially generate oxygen gas from the positive electrode and prevent generation of hydrogen gas from the negative electrode during charging. Also, when the battery is repeatedly charged and discharged, the negative electrode deteriorates, but since the charge reserve part is charged instead of such a part that cannot be charged, there is an advantage that the decrease in charge amount can be prevented. There is.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009]

In order to achieve the above object, activation of a sealed alkaline battery using a nickel hydroxide positive electrode plate containing at least metallic cobalt or a cobalt compound and a negative electrode plate using a hydrogen storage alloy. In the method, after assembling the battery, the first step is to charge the battery at a high current such that nickel hydroxide is immediately charged, and after finishing the charging at the high current, charge the battery at a lower current. And a second step.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

After that, even if the battery is charged with a smaller charging current, the battery voltage is superior to metallic cobalt and cobalt compounds.
The cell voltage does not oxidize first . Therefore, metallic cobalt or the like is not preferentially oxidized over nickel hydroxide. As a result, charging can be performed at a low current, and an activation effect that is almost the same as that when charging is performed at a low current from the beginning can be obtained, and as a result, almost the same battery capacity can be obtained.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

In addition, recent battery-using equipment is set to stop discharging when the battery voltage becomes lower than a certain value, so that the battery will not be completely discharged or over-discharged. Is becoming In such use, even when repeatedly charged and discharged repeatedly, metal cobalt or a cobalt compound discharge is completed at a higher than the battery voltage to oxidize preferentially voltage, during charging because the charge from the battery voltage begins, Metallic cobalt and cobalt compounds are not preferentially oxidized. Therefore, similarly to the above, it is possible to prevent a decrease in the charge reserve (an increase in the discharge reserve).

[Procedure Amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

After this, the cylindrical sealed nickel-hydrogen storage battery produced as described above was applied with a current of 1.0 C (1200 m).
A) for 15 minutes, 0.25C (300mA) for 6 hours,
After initial charging, discharging was performed at 1.0 C to complete the initial activation. The battery that has been initially activated under the above conditions is hereinafter referred to as (a) battery. [Comparative Example] The same procedure as in the above Example except that the initial charging of the cylindrical sealed nickel-hydrogen storage battery produced in the same manner as in the Example was performed at 0.25 C for 7 hours. Initial activation was performed.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

The values in Table 1 are expressed as percentages with respect to the negative electrode capacity when the negative electrode capacity is 100. First, as is clear from FIG. 2, in the battery (a) of the present invention, a flat portion due to the oxidation of metallic cobalt and a cobalt compound is not recognized around the battery voltage of 0.9 V to 1.1 V. As a result, it can be confirmed that the nickel hydroxide of the positive electrode is being charged without delaying the charging of the negative electrode, so that the reduction of the charge reserve of the negative electrode can be suppressed.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

Further, as is clear from Table 1, it was confirmed that the battery (a) of the present invention has a smaller discharge reserve and a larger charge reserve than the battery (x) of the comparative example. It is considered that this makes it possible to suppress a decrease in the cycle life of the battery. This also see that the high characteristics discharge collection efficiency of the negative electrode hydrogen absorbing alloy is fully utilized at the same time.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

Furthermore, for the battery capacity, and almost the same value as when subjected to charging with a low current, even when subjected to charging at a high current from here to the initial charge, charge and
It can be confirmed that sufficient activation can be performed .

Claims (1)

[Claims] 1. A method for activating a sealed alkaline battery using a nickel hydroxide positive electrode plate containing at least metallic cobalt or a cobalt compound and a negative electrode plate using a hydrogen storage alloy. It has a first step of charging the battery with a high current such that nickel oxide is charged, and a second step of charging the battery with a lower current after completion of the charging with the high current. And method for activating a metal hydride storage battery.