JP2000215882A - Nickel-metal hydride battery and method of using the same - Google Patents

Abstract

(57) [Summary] A liquid container that can be opened and closed is provided in a battery container. When the internal resistance of the battery is greater than 1.5 times the initial internal resistance of the battery, replacement is performed until the internal resistance of the battery becomes 1.5 times or less the initial internal resistance of the battery. [Effect] The life of the battery can be substantially extended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel-metal hydride storage battery which can be used after returning its capacity and a method of using the same.

[0002]

2. Description of the Related Art In recent years, nickel-metal hydride batteries have been used for applications requiring high output, such as electric vehicles and electric tools.

This nickel-metal hydride storage battery has a structure in which a positive electrode using nickel oxide and a negative electrode using a hydrogen storage alloy are separated by a synthetic resin separator and housed in a sealed battery container together with an alkaline electrolyte. The battery has excellent charge-discharge cycle characteristics, such as maintaining a capacity of 80% or more even when charge and discharge are repeated 500 times or more.

[0004]

As described above, the nickel-metal hydride storage battery is a closed type and has a long charge / discharge cycle life.
If the capacity has been significantly reduced after using the specified number of times,
Judging that the life of the battery had expired, he disposed of it. The batteries that have been disposed of are collected for recycling, and the usable materials are extracted and reused. However, one of the materials that make up the battery
It is difficult to reuse 00%, and there has been a demand for creating an effective method of using a battery whose life has expired.

In recent years, nickel-metal hydride storage batteries have been used for EVs (for HEVs).
Longer life, such as over cycles, is being required.

The present invention has been made in view of the above.

[0007]

The nickel-metal hydride storage battery of the present invention has been conceived by finding that the battery characteristics can be restored by injecting a new electrolyte into a nickel-metal hydride storage battery whose life has expired. In addition, the battery container is provided with an openable and closable liquid injection section.
Further, the method of using the nickel-metal hydride storage battery of the present invention is a method capable of efficiently extending the battery life, and is used when the internal resistance of the battery is larger than 1.5 times the initial internal resistance of the battery. The replacement is performed until the internal resistance of the battery becomes 1.5 times or less the initial internal resistance of the battery.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The nickel-metal hydride storage battery of the present invention
It is characterized by having a liquid injection part that can be opened and closed, for example, the liquid injection part comprises a threaded circular hole provided in the battery container, and a threaded stopper. It is preferable that the plug is screwed to the hole in an airtight state, and in this case, in order to easily maintain the airtightness, the diameter of the hole is three times or less the thickness of a member constituting the periphery of the hole. Good to do.

The position of the liquid injection section is not particularly limited. However, in the case of a screwed structure including a hole and a plug as described above, the liquid injection section is a flat portion of a battery container, for example, a cylindrical battery. In this case, it is preferable to provide it on the bottom or lid of the container.

[0010] Further, it is preferable that the liquid injection section is configured to maintain an airtight state. When a safety valve is provided in the battery, the battery is always kept airtight below the operating pressure of the safety valve. It is good to configure. In this case, for example,
In the case of a screwed structure including a hole and a plug as described above, it is preferable to form a sealing material on the threaded surface of the plug to maintain an airtight state.

As the sealing material, a material resistant to an alkaline electrolyte, for example, Teflon or nylon is preferable.

The method of using the nickel-metal hydride storage battery of the present invention is, for example, a method of use suitable for the nickel-metal hydride storage battery of the present invention described above, and is a method capable of restoring the performance of the battery when its life has expired. The performance is restored by performing rehydration.

[0013] The timing of the replacement fluid is not particularly limited, but is, for example, when the battery reaches the end of its life or when the performance of the battery before that has deteriorated. One of the causes of the life of nickel-metal hydride batteries is that the internal resistance increases due to the exhaustion of the electrolyte in the separator due to the swelling of the positive electrode or the pulverization of the hydrogen storage alloy. You can also judge to some extent by looking at the change in. Therefore, for example, the time when the internal resistance is twice as large as the initial internal resistance can also be used as a guide for replacement fluid, especially in the case of a battery such as an EV battery which requires a large and large output. Suitable as a guide.

Further, although the performance of the battery is recovered by the replacement fluid, it is difficult to completely return the battery to its original state. When the degree of return is measured by using the internal resistance as a guide, the reliable return is 1.5 times the initial internal resistance. Up to double the value. Therefore, even if rehydration is performed at a point in time when the internal resistance does not exceed 1.5 times the initial value, the effect is not so large and it is not efficient. For this reason, it is preferable to perform the replacement when the internal resistance of the battery is greater than 1.5 times the initial internal resistance of the battery.

It is preferable that the replenishing is performed while observing the internal resistance of the battery. Since the reliable return is 1.5 times the initial internal resistance, the internal resistance of the battery is one of the initial internal resistance of the battery. It is efficient and efficient to perform rehydration until the value becomes 0.5 times or less. In addition, if the rehydration is interrupted at a point where the return of the internal resistance is small, for example, 1.8 times, the life after the rehydration is shortened.

As a liquid component used for the replacement fluid, pure water is most preferable, but a solution having the same composition as the electrolyte solution of the battery may be used.

EXAMPLES (Production of a positive electrode plate) Nickel hydroxide powder 1 having an average particle size of 10 μm in which small amounts of cobalt and zinc were coprecipitated.
A paste was prepared by dispersing 00 parts by weight, 10 parts by weight of cobalt hydroxide powder, and 5 parts by weight of zinc oxide powder in a 0.4 wt% carboxymethyl cellulose aqueous solution. A paste-type nickel hydroxide positive electrode plate was prepared by filling, drying, and pressing a paste into 95% porosity nickel foam (manufactured by Sumitomo Electric, trade name: Celmet). (Production of negative electrode plate) The composition is MmNi _3.55 Co _0.75 Mn _0.4
A hydrogen absorbing alloy powder 100 parts by weight consisting al _0.3, the carbon black 3 parts by weight as a conductive agent is dispersed in a 1 wt% aqueous solution of polyvinyl alcohol was prepared a paste. This paste was applied to a perforated steel plate, dried and pressed to produce a paste-type hydrogen storage alloy negative electrode plate. (Production of Battery) An alkaline aqueous solution having a molar ratio of potassium hydroxide, sodium hydroxide and lithium hydroxide of 6: 1: 0.5 was prepared and used as an electrolyte. The separator was manufactured by graft-polymerizing acrylic acid onto a polypropylene nonwoven fabric having a thickness of 0.18 mm and a weight per unit area of 70 g / m ² , and performing a hydrophilic treatment. The nickel hydroxide positive electrode plate, the hydrogen storage alloy negative electrode plate, and the separator are wound to form a spiral cylindrical electrode plate group, which is inserted into a cylindrical battery can, and then the electrolyte is poured. After the liquid was sealed, a cylindrical nickel-hydrogen storage battery was produced.

FIG. 1 is a perspective view showing the external appearance of a cylindrical nickel-metal hydride battery according to this embodiment, and FIG. 2 is a partial cross-sectional view of a liquid injection section having a screwed structure. In the present battery, the liquid injection section 1 is provided in a lid portion of the container, and as shown in FIG.
And the threaded plug 4 and the reinforcing plate 5, the diameter of the thread of the plug 4 is 2 mm, the wall pressure of the battery container 2 is 0.5 mm,
The wall pressure of the reinforcing plate is 1.0 mm.

FIG. 3 is a partial cross-sectional view of a liquid injection section having another screwing structure. The liquid injection section 1 has a threaded circular hole 3 provided in a battery container 2 and a screw cutting section. The diameter of the screw portion of the plug 4 is 3 mm, and the wall pressure of the battery container 2 is 1.2 mm. When the thickness of the container is increased, such a structure can be adopted.

The nominal voltage of this battery is 1.2 V, and its internal resistance is 1 mΩ. Also, at a current value of 10 A, 0.8
The capacity when discharged to V is 50 Ah. Using this battery, charge at 25 A for 100 minutes and 48 A at 50 A
The discharge was repeated for minutes. When the time when the voltage at the time of discharging became lower than 0.8 V was defined as the cycle life of this battery, the life was 400 cycles. At this time, the internal resistance of the battery was 2 mΩ.

The stopper 4 of the filling part 1 of the battery which has reached the end of its life is opened, pure water of 5% of the volume of the initially injected electrolyte is replenished, the stopper 4 is closed and left for 12 hours. . Thereafter, the battery was charged at a current value of 8 A for 5 hours, and then charged at a current value of 8 A of 1.0 V
Until discharge. By this processing, the internal resistance of the battery becomes 1.
It decreased to 4 mΩ. This battery was charged at a current value of 10 A for 6 hours, and then discharged at 10 A to 0.8 V to measure the capacity. As a result, the capacity was 48 Ah.
And, for this battery, 100
The battery was revived when charging for 50 minutes and discharging for 48 minutes at 50 A were repeated, and the life was 200 cycles. The internal resistance of the battery at this time is
It was 2.1 mΩ. That is, the above processing further extended the life of 200 cycles.

Further, the liquid injection section 1 of the battery which has reached the end of its service life.
Was opened, and 4% of the volume of the electrolyte initially injected was replenished with pure water, and the stopper 4 was closed and left for 12 hours. Thereafter, the battery was charged at a current value of 8 A for 5 hours, and then discharged to 1.0 V at a current value of 8 A. The internal resistance of this battery is 1.6
Because it was mΩ, it was charged again at a current value of 8 A for 5 hours,
Next, when the battery was discharged to 1.0 V at a current value of 8 A, the internal resistance of the battery became 1.5 mΩ. 10A for this battery
After charging for 6 hours at a current value of 0.8 V at 10 A
The capacity was measured by discharging to 46
Ah. Then, for the battery,
When the battery was repeatedly charged at 5 A for 100 minutes and discharged at 50 A for 48 minutes, it was found that the battery was restored again, and the battery had a life of 180 cycles. At this time, the internal resistance of the battery was 2.2 mΩ. That is, the above processing further extended the 180 cycle life.

As described above, when the internal resistance of the battery is larger than 1.5 times the initial internal resistance of the battery, the internal resistance of the battery is less than 1.5 times the initial internal resistance of the battery. It was found that the use of the method of the present invention, in which replenishment was performed until the value reached, was able to substantially extend the life of the battery.

As shown in the present embodiment, in the method of use of the present invention, when performing rehydration, the replenisher is left for a predetermined time after the rehydration, charged with a current value of 0.2 C or less, and then charged with 0.2 C or less. It is preferable to discharge at a current value of Further, charging is preferably limited to 80% or less of the initial capacity, and is preferably repeated until the internal resistance becomes 1.5 times or less of the initial internal resistance.

[0024]

According to the present invention, a nickel-metal hydride battery which can be used repeatedly by performing replacement fluid can be realized. According to the method of use of the present invention, the battery of the present invention can be used efficiently.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the external appearance of a cylindrical nickel-metal hydride battery of the present embodiment.

FIG. 2 is a partial cross-sectional view of a liquid injection section having a screw fastening structure.

FIG. 3 is a partial cross-sectional view of a liquid injection unit having another screwing structure.

[Explanation of symbols]

1: Injection part 2: Battery container 3: Hole 4:
Plug 5: Reinforcement plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H011 AA03 GG05 KK01 KK02 5H023 AA03 AS02 AS10 CC11 CC15 CC19 CC30

Claims (4)

[Claims] 1. A nickel-metal hydride storage battery comprising a battery container provided with a liquid inlet that can be opened and closed. 2. The liquid injection part comprises a threaded circular hole provided in a battery container, and a threaded stopper.
The nickel-metal hydride storage battery according to claim 1, wherein the diameter of the hole is three times or less the thickness of a member forming the periphery of the hole, and the plug is screwed to the hole in an airtight state. . 3. The battery is provided with a safety valve, and a sealing material is formed on a threaded surface of the plug so that the plug is kept airtight at an operating pressure of the safety valve or less. 3. The nickel-metal hydride storage battery according to claim 2, wherein the battery is screwed in an airtight state. 4. When the internal resistance of the battery is larger than 1.5 times the initial internal resistance of the battery, the internal resistance of the battery becomes 1.5 times or less the initial internal resistance of the battery. A method of using a nickel-metal hydride storage battery, characterized in that replenishment is performed until the battery is replaced.