JPH05174869A - Processing method for sealed type nickel-hydrogen battery - Google Patents

Abstract

PURPOSE:To suppress the inner pressure of the generated gas, to reduce the charge and discharge cycle number until the initial activation, and to realize a formation at a high efficiency and a high ecconomy, by carrying out a preliminary charging process prior to applying an initial charging process after the assembly of a battery is completed. CONSTITUTION:After leaving a sealed battery whose assembly is completed but the formation is not yet finished for one hour at a room temperature, a charging is carried out for one hour at 0.2 deg.C (the charging of 20% of the rating capacity of the battery). After that, it is left for 15 hours, and then the initial charging process is carried out at 0.2 deg.C for charging 150% of the rating capacity, a discharge is carried at 0.2 deg.C to one V, and by carrying out three rounds of charge and discharge at a room temperature, this battery is obtained. That is, by carrying out a preliminary charging process at the capacity less than 100% of the rating capacity, the oxidization of the alloy surface of the negative electrode is prevented even though the battery is left thereafter, the inner pressure can be reduced in the initial charging process, and the charge and discharge cycle for the initial activation can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a sealed nickel hydrogen battery.

[0002]

2. Description of the Related Art Conventionally, the manufacture of a sealed nickel-hydrogen battery of the type that uses a hydrogen storage alloy as a negative electrode active material as a negative electrode active material and absorbs and releases hydrogen by charging and discharging has not yet been completed at the completion of assembly of the sealed nickel-hydrogen battery. In many cases, neither the positive electrode nor the negative electrode has been formed, and then the initial charging process has formed.

[0003]

In the production of the above-mentioned conventional sealed nickel-hydrogen battery, there are several hours to several tens of hours between the completion of the assembly of the sealed nickel-hydrogen battery and the start of the initial charging step. Therefore, during that time, the unformed sealed battery is often left unattended. When the sealed battery is subjected to the initial charging process after being left in this way, the internal pressure increases due to the gas generated inside, and it is charged until a predetermined initial activation is obtained, that is, a predetermined battery capacity is obtained. There are inconveniences such as a tendency that the number of discharge cycles tends to increase.
It is considered that this inconvenience occurs because the unformed negative electrode, that is, the surface of the hydrogen storage alloy, is adversely affected by oxidation or the like during the standing. Therefore, even if the assembled battery is left to stand until it is subjected to the initial charging process, it is less likely to be adversely affected by the above-mentioned oxidation and the like, and the gas internal pressure generated during the initial charging process is reduced. It is desirable to reduce the number of charge / discharge cycles for initial activation so that a highly efficient sealed battery can be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a method for treating a sealed nickel-hydrogen battery that satisfies the above-mentioned needs. A feature of the hydrogen battery is that the battery is charged to 100% or less of the rated capacity before the initial charging process after the assembly is completed.

[0005]

As described above, the unformed sealed battery is charged to 100% or less of the rated capacity before the initial charge, so that the amount of oxygen gas generated is small and the negative electrode is shifted to the base side. You can Therefore, the sealed nickel-metal hydride battery once subjected to the charging process in this way is less likely to be adversely affected by oxidation or the like even if left for a while.
When the initial charging process is performed after that, the internal pressure due to the generated gas can be kept low, and the number of charge and discharge cycles until the initial activation can be reduced, and the sealed type is highly efficient and economically formed. A nickel hydrogen battery is obtained.

[0006]

EXAMPLES Examples of the present invention will be described below. A positive electrode plate and a negative electrode plate are manufactured in the same manner as in the conventional method. That is,
As the positive electrode plate, for example, a conductive material and a thickening agent are added to and mixed with a nickel hydride powder at a predetermined mixing ratio, the resulting slurry is filled into a foamed nickel substrate, dried, and rolled,
A given nickel electrode plate was cut into a given size to obtain a positive electrode plate. On the other hand, as the negative electrode plate, for example, SLmNi _4.0 Co _0.5 Al _0.5 which is a hydrogen storage alloy is mechanically crushed, and PVdF (polyvinylidene fluoride) powder is used as a binder in the obtained alloy powder. 0.3 wt. %, Ni powder 1
5 wt. % Of CMC as a thickener.
% And mixed to obtain a slurry negative electrode active material mixture,
This is filled and applied on both sides of a porous sheet such as expanded metal, dried and rolled, and then heat-treated at 180 ° C. for 1 hour in a vacuum atmosphere and cut to form a hydrogen storage alloy electrode plate, that is, a negative electrode plate. Obtained. These positive electrode plate and negative electrode plate are laminated via a nylon separator and wound to form a wound electrode plate group, which is housed in a cylindrical battery can and injected with a predetermined amount of an alkaline electrolyte of a predetermined concentration. , With battery cover, AA
-Assembly of Type 1000 mAh cylindrical sealed nickel-hydrogen battery. Thus, a large number of such unformed sealed batteries were prepared for the comparative test. A dedicated sensor was set in each sealed battery for measuring the battery internal pressure.

Regarding such an unformed sealed battery,
According to the conventional manufacturing method, after leaving for between numbers or tens of hours,
Perform the initial charging process. For example, after leaving the assembled sealed battery at room temperature for 15 hours, the initial charging treatment shown in Table 1 below was performed to manufacture a sealed nickel-hydrogen battery.
This battery is hereinafter referred to as a conventional battery. On the other hand, according to the present invention, the sealed battery thus assembled is left at room temperature for 1 hour and then charged at 0.2 C for 1 hour (that is, 20% of the rated capacity of the battery). After that, the battery was left for 15 hours, and then the initial charging treatment shown in Table 1 below was performed to manufacture a sealed nickel-hydrogen battery. This battery is hereinafter referred to as Battery A of the invention. Separately, the assembled battery is left at room temperature for 14 hours, charged at 0.2 C for 1 hour (that is, 20% of its rated capacity), and then left for 15 hours. Then, the initial charging treatment shown in Table 1 below was performed to manufacture a sealed nickel-hydrogen battery. This battery is hereinafter referred to as Battery B of the invention. The first charging process above is
The battery was charged to 150% at 0.2 C, and discharged at 0.2 C to 1 V by performing three charge / discharge cycles at room temperature. However, after two charge / discharge cycles, the sample was left at 40 ° C. for 24 hours and then the third charge / discharge cycle was performed. The battery capacity, the average discharge voltage, and the internal pressure of each of the above conventional battery, the present invention battery A, and the present invention battery B were measured after each charge / discharge cycle. The results are shown in Table 1 below.

[0008]

[Table 1]

As can be seen from Table 1, when the sealed battery was assembled for 15 hours according to the conventional method and then left to stand for 15 hours, the battery capacity at the time of one charge / discharge cycle 1.02Kgf is only in the following 990mAh 1000mAh, not only does not reach the rated capacity, the internal pressure is, in the charge-discharge cycle the first time in 0.80Kgf / ^cm 2, 2 time in 0.92Kgf / ^cm 2, 3 time / C
A large internal pressure of m ² was generated. On the other hand, after completion of the sealed battery assembly according to the present invention, the battery is left for 15 hours before the above-mentioned charging process (hereinafter referred to as precharging process) before the initial charging process
After that, even after being left for 15 hours and 14 hours respectively, the battery capacity already reached 1000 mAh or more at the first charge / discharge cycle in each initial charge treatment, while the internal pressure was changed to charge / discharge. cycle 1st at 0.4 kgf / cm ² or less and low and the third time also 0.45Kgf / cm ² or less in the Isuzu words, compared to the case without precharge process, the internal pressure was significantly reduced. Also, the average discharge voltage was improved.

As described above, depending on the presence or absence of the precharge process,
The reason why the battery capacity, the internal pressure, and the like differ as described above in the initial charging process is considered as follows. That is, as in the conventional case, the unformed negative electrode is at least oxidized during the standing period after completion of the sealed battery assembly and before the transfer to the initial charging step. As a result, if the subsequent initial charging process is performed, oxygen gas is remarkably generated in the process, the internal pressure increases, and the initial activation takes time. On the other hand, if the unformed sealed battery is subjected to the pre-charging process before the initial charging process, the unformed and noble side negative electrode is subjected to the reducing action and becomes the base side. As a result, in the initial charging process,
It is presumed that the generation of oxygen gas is small, the internal pressure is reduced, and the initial activation is obtained early.

In this case, the precharge treatment is performed within 100% or less of the rated capacity of the battery to be treated, usually within the range of 5 to 100%, so that the precharge treatment is performed to the extent that the battery is not completely charged. Oxidation of the negative electrode due to the precharge treatment can be prevented in advance by preventing the generation of _two gases. In the above-described specific example, the precharge process is performed after leaving the closed battery for a long time after completion of the assembly, but the precharge process may be performed immediately after the completion of the assembly. In short, the above-mentioned effects of the present invention can be brought about by carrying out the above-mentioned charging treatment before entering the initial charging step, and the object can be achieved.

[0012]

As described above, according to the present invention, when precharging treatment is performed at 100% or less of the rated capacity of the sealed nickel-metal hydride battery after completion of assembly and before initial charging treatment. The effect is that the oxidation of the alloy surface of the negative electrode is prevented even if it is left unattended after that, the internal pressure can be reduced in the initial charge treatment, and the charge / discharge cycle for initial activation can be reduced. Have.

Claims (1)

[Claims] 1. An unformed hermetically sealed nickel-hydrogen battery that has been assembled is charged to 100% or less of its rated capacity before the initial charging after the assembly is completed. Treatment method of sealed nickel-hydrogen battery.