JP3308325B2 - Method for manufacturing nickel-hydrogen secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a nickel-hydrogen secondary battery, and more particularly to a method of manufacturing a secondary battery having an improved activation step.

[0002]

2. Description of the Related Art In the manufacture of an alkaline secondary battery typified by a nickel cadmium secondary battery, a positive electrode and a negative electrode are activated by chemical conversion treatment and incorporated into an outer can, and then subjected to a desired aging and a charge / discharge process. A method of selecting the capacity by passing through the process.

On the other hand, in the case of a nickel-metal hydride secondary battery, the hydrogen storage alloy negative electrode is not subjected to a chemical conversion treatment before being incorporated in the outer can, but is incorporated into the outer can in an inactive state and activated by the first charge / discharge. It can be performed. However,
Since the degree of activation of the negative electrode cannot be sufficiently increased by the formation in the battery, there is a problem that the discharge voltage and the discharge capacity are low in the initial stage of use. Therefore, when the capacity of the secondary battery is selected in the charging / discharging process, the secondary battery has a reduced discharge capacity due to a low degree of activation, or has a reduced discharge capacity due to a defective product. It was difficult to determine whether the battery was a secondary battery. In other words,
It becomes difficult to perform a high-accuracy capacity selection inspection. Further, the secondary battery is activated as the charge / discharge cycle is repeated to be activated and the discharge capacity is improved.However, since each of the secondary batteries subjected to the chemical conversion in the battery has a different degree of improvement, when the battery is an assembled battery, There is a problem that the discharge capacity of the unit cell varies.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the conventional problems, and is intended to provide a nickel-hydrogen secondary battery capable of sufficiently improving a discharge capacity and a discharge voltage before a capacity screening test. It is intended to provide a manufacturing method.

[0005]

Means for Solving the Problems Nickel water according to the present invention
A method of manufacturing a nickel-metal hydride secondary battery includes a positive electrode including nickel oxide as an active material, a negative electrode including a hydrogen storage alloy as an active material, a separator, and a step of assembling a nickel-metal hydride secondary battery including an electrolyte . when at least one cycle facilities charge-discharge cycle to the secondary battery, standing before aging
The discharge of the secondary battery was performed at a discharge rate of 0.2 C or more.
It is performed until the remaining capacity reaches 20% or less of the total discharge capacity.
That step and said the step of subjecting the remaining capacity release <br/> location aging on standing secondary battery having a step of subjecting the capacitance selection test by full charge and discharge <br/> electric operation in the secondary battery and it is characterized in the this <br/> comprising and.

The leaving aging is performed to sufficiently activate the hydrogen storage alloy negative electrode. For this reason, it is desirable that the standing aging is performed at a temperature of 25 ° C to 60 ° C.

The state in which the remaining capacity is small means a capacity obtained by discharging the battery to a predetermined voltage at a discharge rate of 0.2 C or more to 20% or less of the total discharge capacity. .

[0008]

According to the present invention, a charge / discharge cycle is performed on a nickel-metal hydride secondary battery including a positive electrode containing nickel oxide as an active material, a negative electrode containing a hydrogen storage alloy as an active material, a separator, and an electrolyte. After at least one cycle, the storage battery is subjected to standing aging with a small remaining capacity, whereby the negative electrode can be sufficiently activated and the capacity of the negative electrode can be improved. As a result, the discharge voltage and the discharge capacity can be sufficiently improved, so that the quality of the battery itself can be determined without being affected by the degree of activation in the capacity selection after the leaving aging. Therefore,
Since the number of batteries determined to be defective is reduced, the yield is improved. Further, when a battery pack is manufactured from the secondary batteries selected by the test, a battery pack with reduced variation in discharge capacity due to the unit cells can be obtained.

[0009]

An embodiment of the present invention will be described below with reference to FIG. Examples 1 to 5

First, a step portion 2 was formed by expanding an opening of a metal-made bottomed rectangular cylindrical outer can 1 also serving as a negative electrode terminal. Subsequently, an electrode body 6 is formed by laminating a positive electrode 4 containing nickel oxide as an active material and a negative electrode 5 containing a hydrogen storage alloy as an active material, sandwiched between two-folded separators 3. 6 was stored in the outer can 1. Subsequently, an alkaline electrolyte was accommodated in the outer can 1.

Next, a group of sealing lids 9 having both an explosion-proof function and a positive electrode terminal was placed on an insulating gasket 8 having a rectangular hole with a rectangular opening at the bottom. The sealing lid group 9
Is a sealing plate 11 having a gas vent hole 10 opened in the center,
A cap which is placed on the sealing plate 11 so as to cover the gas vent hole 10 and is made of, for example, synthetic rubber; and a cap which is welded to the sealing plate 11 so as to surround the safety valve 12 and has a gas vent hole 13 And a terminal board 14 having the same shape. Subsequently, the other end of the positive electrode lead 15 having one end connected to the positive electrode 4 was connected to the lower surface of the sealing plate 11. Subsequently, the insulating gasket 8 on which the sealing lid group 9 was placed was placed on the step 2 of the outer can 1. Next, the sealing lid group 9 was airtightly attached to the outer can 1 by caulking and fixing the opening of the outer can 1.

Thereafter, the secondary battery assembled by the above-described method was charged at 0.1 CmA to 150%. Then,
Discharge and standing aging were performed under the conditions shown in Table 1 below, and the negative electrode was activated to produce a secondary battery having a capacity of 600 mAh. In addition, the remaining capacity at the time of the discharge is as follows:
The ratio was calculated as a percentage of the total discharge capacity of the secondary battery, and is shown in Table 1. Table 1 Discharge conditions before leaving aging Conditions for leaving aging Discharge current Cut-off Remaining capacity Temperature Time Voltage (CmA) (V) (%) (° C) (h) Example 1 1 1.0 20 25 72 Example 21 1.0 20 45 24 Example 3 1 0.8 13 25 72 Example 4 1 0.8 13 45 24 Example 5 0.2 1.0 4 25 72 Comparative Example 1, Comparative Example 2 Table 2 below shows A secondary battery was manufactured in the same manner as in Examples 1 to 5, except that discharge and standing aging were performed under such conditions. Table 2 Discharge conditions before leaving aging Conditions for leaving aging Discharge current Cut-off Remaining capacity Temperature Time Voltage (CmA) (V) (%) (° C) (h) Comparative Example 1 1 1.0 20 Not implemented Comparative Example 21 1.1 29 25 72

The batteries produced in Examples 1 to 5 and Comparative Examples 1 and 2 were charged at 130% at 1 CmA and then discharged to 1.0 V at 1 CmA, the discharge capacity was measured, and a capacity selection test was performed. After that, charge 150% at 0.2C and cut off voltage to 1V
The discharge capacity and average discharge voltage at the time of performing the 1C discharge described above were measured.

Among these results, regarding the discharge capacity at the time of the capacity screening and the discharge capacity at the next cycle, the discharge capacity at the time of the screening test of the battery of Example 1 was set to 100, and the discharge capacity ratio was calculated based on this. This is shown in the graph of FIG. Table 3 below shows the average discharge voltage in the next cycle.
It was shown to.

According to FIG. 2 and Table 3, the batteries of Examples 1 to 5 are:
The discharge capacity and the average discharge voltage at the time of the screening test and at the next cycle can be sufficiently improved, and since the capacity difference between the discharge capacities is small, the accuracy of the screening test is good.

On the other hand, in the batteries of Comparative Examples 1 and 2, the discharge capacity and the average discharge voltage during the screening test were extremely low due to the insufficient degree of activation. Since the difference between the discharge capacity in the next cycle and the discharge capacity is large, the accuracy of the screening test may be reduced.

Further, the batteries manufactured in Examples 1 to 5 and Comparative Examples 1 and 2 were charged at 125% with 1C, and 90 cycles of 1C discharge with a cut-off voltage of 1 V were performed for 90 cycles to measure the change in discharge capacity. did. With respect to the measured discharge capacity, the discharge capacity at the time of the capacity selection test of the battery of Example 1 was set to 100, and the discharge capacity ratio was calculated based on the discharge capacity. The result is shown in the graph of FIG.

FIG. 3 shows that the batteries of Examples 1 to 5 maintain a high discharge capacity from the beginning of the charge / discharge cycle test, and the tendency does not change even after the completion of 90 cycles. on the other hand,
The batteries of Comparative Examples 1 and 2 had an extremely low discharge capacity at the beginning of the charge / discharge cycle test as compared with Examples 1 to 5, and when they were subjected to 90 cycles, the batteries of Examples 1 to 5 improved to the discharge capacity level at the start of the charge / discharge cycle However, it can be seen that the discharge capacity is significantly different between the start of the charge / discharge cycle and the end of the 90 cycle.

The current value in the charging / discharging process performed in the first to fifth embodiments is not limited to the above-mentioned condition, and step charging / discharging in which the current value is changed stepwise may be used. Can be. In Examples 1 to 5,
Although the present invention has been described with reference to a prismatic nickel-metal hydride secondary battery, the present invention can be similarly applied to a cylindrical nickel-metal hydride secondary battery.

[0020]

As described above in detail, according to the present invention, nickel having an effect that the discharge capacity and discharge voltage before the screening test can be sufficiently improved and the screening test accuracy can be improved. A method for manufacturing a hydrogen secondary battery can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a nickel-metal hydride secondary battery manufactured by the manufacturing method of the present invention.

FIG. 2 is a diagram showing a discharge capacity ratio at the time of a capacity selection test and at the next cycle.

FIG. 3 is a diagram showing a change in a discharge capacity ratio with a change in the number of cycles.

[Explanation of Symbols] 3 ... separator, 4 ... positive electrode, 5 ... negative electrode.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Taguchi, the inventor 3- 4-10 Minamishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Battery Co., Ltd. (72) Tomoyuki Ono 3-4-1, Minamishinagawa, Shinagawa-ku, Tokyo No. Toshiba Battery Co., Ltd. (72) Inventor Hideaki Kitazume 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Co., Ltd. (56) Reference JP-A-2-267872 (JP, A) JP JP-A-4-126370 (JP, A) JP-A-5-303981 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/24-10/34

Claims (1)

(57) [Claims] A positive electrode containing a 1. A nickel oxide as an active material, assembly and the negative electrode containing a hydrogen absorbing alloy as an active material, a separator, a nickel-hydrogen secondary battery comprising an electrolyte solution
And teru step, when to at least one cycle <br/> facilities discharge cycle to the secondary battery, standing before aging discharge, release of more than 0.2C
At the power rate, the remaining capacity of the secondary battery is 2% of the total discharge capacity.
A step performed to reach 0% or less, a step of performing left aging to leave a rechargeable battery having the remaining capacity, and a step of subjecting the capacitor screening test by the operation of full charge and discharge to the battery comprises A method for manufacturing a nickel-metal hydride secondary battery.