JPH11238530A - Cooling method for modular battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the temperature rise of a battery effectively, during charging and discharging by having a liquid coolant flow through a space part formed between cells and arranging the battery in a tank storing the coolant such that the battery immerses the upper ends of its ribs in the coolant. SOLUTION: Respective cells are connected electrically together in series through connecting members, ribs 6 of the respective cells adjacent to each other are abutted against each other, and a space part opened at its upper and lower part is formed in a part between them. Water used as a coolant is filled in an inside tank 21, a modular battery 10 is installed in it, the height of the opening part of the inside tank 21 is set so as to be higher than the upper end of the rib 6 of each cell and lower than the upper surface of a lid. When a chiller 26 is started, the water in a cooling device 20 is circulated. That is, the water cooled by the chiller 26 flows into the space part through a via water supplying part 23, passes through the space part while absorbing the heat generated in each of the cells, overflows from the inside tank 21, and is supplied to the chiller 26 again by way of an outside tank 22 and a drain pipe 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling method and a manufacturing method for a module battery, and more particularly to a cooling method for charging and discharging the module battery.

[0002]

2. Description of the Related Art Conventionally, alkaline storage batteries typified by nickel-hydrogen storage batteries and nickel-cadmium storage batteries have been used for various electric appliances. In particular, in recent years, nickel-cadmium storage batteries using toxic cadmium have been replaced by nickel-hydrogen storage batteries, which are clean energy, due to increasing environmental problems. Nickel-metal hydride storage batteries use nickel hydroxide as the positive electrode and a hydrogen storage alloy that reversibly stores and releases hydrogen for the negative electrode.Because of their high energy density and high output, It is also attracting attention as a power supply for driving electric vehicles. Since a high voltage of 200 to 300 V is required as a power supply for driving an electric vehicle, it is necessary to connect about 200 cells in series. Therefore, a module battery in which a plurality of unit cells are combined has been proposed. In such a unit cell, a battery case made of a resin such as polypropylene is used in a rectangular parallelepiped housing for weight reduction. Further, in order to maintain heat radiation and mechanical strength, the thickness of the battery case is reduced, and a plurality of ribs are arranged on the outer surface as a reinforcing material. In particular, nickel-metal hydride storage batteries have a high internal pressure, and generate a large amount of heat because the negative electrode reaction that absorbs oxygen at the end of charging is an exothermic reaction.
There is a high need to balance the mechanical strength and heat dissipation of the battery.
Therefore, in order to prevent a temperature rise of the battery during use, a plurality of ribs are arranged in the same direction on the surface of the battery case of the unit cell, and a space is formed between the unit cells by abutting the adjacent unit cell and the rib with each other. Thus, a method of circulating air through the space has been proposed.

In general, an alkaline storage battery is initially charged under conditions that can bring out the performance of the battery prior to shipment, because the condition of the initial activation cycle greatly affects the performance of the battery. Conventionally, such initial charge / discharge has been performed by immersing each cell in cooling water. Initial charging and discharging of single cells one by one is a very time-consuming task and one of the factors that lowers production efficiency. In addition, in order to improve the work efficiency of the initial charge and discharge, it is desired to increase the charge and discharge rate. Internal pressure rises sharply. Therefore, it was difficult to perform charging at a high rate.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a method of cooling a module battery which can be rapidly charged and discharged, particularly a module battery of a nickel hydrogen storage battery. And Further, the present invention provides
An object of the present invention is to provide a method of manufacturing a module battery with high production efficiency.

[0005]

According to the present invention, a battery case having a plurality of ribs vertically arranged on an outer surface thereof, and a positive electrode plate and a negative electrode plate housed in the battery case are alternately sandwiched by a separator. A plurality of unit cells each including a stacked electrode plate group and a pair of electrode columns respectively connected to the positive electrode and the negative electrode, A liquid refrigerant is circulated in the space formed between the cells to cool each cell.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The method for cooling a module battery according to the present invention is directed to a module battery comprising a plurality of rectangular cells having a plurality of ribs vertically arranged on a side surface of a battery case and having the ribs butted against each other. On the other hand, a liquid refrigerant is circulated through a space formed between the cells to cool the cells. In a preferred embodiment of the method for cooling a module battery of the present invention, the module battery is immersed in a coolant up to the upper end of a rib and placed in a tank, and the coolant is circulated through a space between the ribs to be cooled. However, it is preferable that the poles connected to the positive electrode plate and the negative electrode plate are respectively exposed from the liquid level of the refrigerant. Also, so that the refrigerant does not adhere to the pole,
It is preferable to arrange the shield member on the pole.

[0007] More preferably, the module battery is disposed in a tank containing the refrigerant, and the refrigerant is supplied to the tank excessively and overflows from the tank, and the refrigerant is circulated in the space between the cells.
By causing the refrigerant to overflow from the tank, the height of the liquid level of the refrigerant can be stabilized by matching the height of the opening of the tank. Therefore, the battery can be stably brought into contact with the refrigerant, and the cooling efficiency of the battery can be stabilized. In particular, the refrigerant is circulated with the space facing upward. When the refrigerant absorbs heat from the battery, it expands and tends to rise toward the liquid level. When the direction of the convection and the direction in which the refrigerant flows are made to match, the refrigerant circulates smoothly, and more efficient cooling becomes possible. It is preferable to use water as the refrigerant from the viewpoint of cost and handling. The cooling method of the module battery described above can be applied to initial charging and discharging in addition to normal charging. Conventionally, single cells were charged and discharged one by one, but according to the present invention, a plurality of cells can be simultaneously charged and discharged after assembling into a module battery, and more rapid charging and discharging is possible. Therefore, the production efficiency is greatly improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as an embodiment of the present invention, a method for initially charging a nickel-metal hydride storage battery will be described in detail with reference to the drawings.

FIG. 1 shows a nickel-hydrogen storage battery cell used in this embodiment. The nominal capacity of the cell 1 is 100 Ah
It is. Inside the battery case 2 made of polypropylene, an electrode group 7 configured by alternately stacking positive and negative plates with a separator interposed therebetween is accommodated. Here, the positive electrode plate is obtained by mixing nickel hydroxide powder and cobalt hydroxide powder at a weight ratio of 100: 10, and then filling the mixture into a foamed nickel plate. On the other hand, the negative electrode plate had a composition of MmNi _3.6
A mixed powder obtained by adding an appropriate amount of carbon powder, carboxymethylcellulose, and styrene-butadiene rubber to a hydrogen-absorbing alloy powder of Co _0.7 Mn _0.4 Al _0.4 is filled in an iron punching metal whose surface is nickel-plated. Note that a polypropylene nonwoven fabric was used for the separator. An electrolytic solution composed of an aqueous solution of potassium hydroxide to which an appropriate amount of lithium hydroxide has been added is injected into the battery case 2.

The opening of the battery case 2 is sealed by a polypropylene lid 3 fixed by heat welding.
The cover 3 is provided with a safety valve 9 having an operating pressure of 4 × 10 ² kPa in order to prevent an abnormal increase in battery internal pressure. The cover 3 is further provided with pole columns 4 and 5 connected to the positive electrode plate and the negative electrode plate, respectively. The wide side wall of the battery case 2
The height is 160 mm, the width is 110 mm, and on the surface,
A plurality of ribs 6 each having a height of 1.5 mm and a width of 5 mm are arranged in the vertical direction at intervals of 12 mm. Five unit cells 1 were stacked with the side walls provided with the ribs 6 facing each other to produce a module battery 10 as shown in FIG. The unit cells 1 are fixed to each other by crimping aluminum end plates 11 arranged on both end surfaces in the stacking direction with a rod-shaped connecting member 12 made of aluminum. These unit cells 1 are electrically connected in series by a connecting member 14. As shown in FIG. 3, the ribs 6 of these adjacent unit cells 1 are abutted with each other, and a space 13 is formed between the two to open up and down.

The above-described module battery 10 was initially charged using the cooling device 20 shown in FIG. First, a waterproof cap 19 made of polypropylene was covered so as to cover the poles 4 and 5 of the unit cell 1 and the connecting member 14 to protect them from the cooling water. Next, the module battery 10 was placed in the cooling device 20. The cooling device 20
An inner tank 21 and an outer tank 22 that houses the inner tank 21 are provided. A cooling water supply unit 23 is provided at the bottom of the inner tank 21.
The cooling water supply unit 23 has a plurality of holes 23a on its upper surface. The module battery 10 is disposed on the cooling water supply unit 23 of the cooling device 20. The cooling water supply unit 23 is provided with the supply pipe 2
7 is connected to the chiller 26. In addition, the outer tank 22
Are connected by a chiller 26 and a discharge pipe 28. The chiller 26 cools the liquid refrigerant supplied from the outer tank 22 through the discharge pipe 28 to a predetermined temperature, and then supplies the liquid refrigerant to the cooling water supply unit 23 of the inner tank 21 through the supply pipe 27.

First, the inner tank 21 is filled with water as a refrigerant, and the module battery 10 is disposed therein. Here, the height of the opening of the inner tank 21 is set so as to be higher than the upper end of the rib 6 of the unit cell 1 and lower than the upper surface of the lid 2. When the chiller 26 is started, water circulates in the device 20 as shown by the arrow in the figure. That is, chiller 2
The water cooled in 6 is supplied to the cooling water supply unit 23 and flows into the space 13 of the module battery 10 through the hole 23a. The water that has flowed into the space 13 passes through the space 13 while absorbing heat generated in the unit cells 1 while flowing upward. The cooling water that has passed through the space 13 is then
It overflows and flows into the outer tank 22. The water that has flowed into the outer tub 22 is again supplied to the chiller 26 from the discharge pipe 28 and cooled. Here, since the liquid level of the cooling water in the inner tank 21 is higher than the upper end of the rib 6 of the unit cell 1, the cooling water flows smoothly through the space 13 between the unit cells 1. Further, since the liquid level of the cooling water is lower than the upper surface of the lid 2, the poles 4 and 5 are prevented from being immersed in the cooling water. Needless to say, the poles and the connecting members 14 of the module battery 10 are waterproofed by the waterproof cap 19 so that water does not adhere thereto as described above.

Using the above cooling device, initial charging was performed at a current of 50 A, that is, 0.5 CA. At this time, chiller 2
The temperature of the water circulated through 6 was adjusted to 25 ° C. and the flow rate was adjusted to 6.0 liters / minute.

Comparative Example 1 Air having a temperature of 25.degree.
The battery was similarly charged while supplying at m / s.

<< Comparative Example 2 >> A module battery 10 was placed in a tank having the same volume as the inner tank used in the above-described embodiment, and water was poured into the module battery 10 so that the water level was about the same as in the above-described embodiment. did. Then, the water was circulated at a flow rate of 6.0 liter / min while cooling to 25 ° C. with a chiller. That is,
The module battery 10 was cooled without performing the overflow and forced circulation of the cooling water in the space as in the example.

In the cooling methods of the above Examples and Comparative Examples, temperature changes during charging were observed. The result is shown in FIG. As is clear from FIG. 5, according to the cooling methods of Comparative Example 1 and Comparative Example 2, the temperature of the battery greatly increases as charging progresses. In particular, according to the air-cooled Comparative Example 1, the internal pressure of the battery reached the operating pressure of the safety valve during charging, and further charging was impossible. On the other hand, according to the cooling method of the example, although the temperature of the battery gradually increased, it was constant at approximately 30 ° C. That is, according to the cooling method of the embodiment, it can be understood that the temperature of the battery can be prevented from rising even when rapid charging is performed, and that efficient charging is possible.

As described in the above embodiment, in the module battery having the ribs on the surface where the unit cells overlap,
By circulating the refrigerant through the space formed between the cells, the cells can be effectively cooled. In particular, by providing the ribs in the vertical direction and circulating the refrigerant upward from below, the refrigerant can be efficiently circulated and effective cooling can be achieved. Also, by causing the refrigerant to overflow from the inner tank, the liquid level of the refrigerant can be made constant, and stable cooling can be performed. The cooling method as described above is effective not only for initial charging and discharging but also for cooling during normal use. In particular, rapid cooling is possible because effective cooling is possible. Of course, the present invention
The present invention is not limited to cooling of a nickel-metal hydride storage battery, but may be applied to other storage batteries, for example, a nickel-cadmium storage battery or a module battery of a lead-acid storage battery.

[0018]

According to the present invention, it is possible to provide a module battery cooling method capable of effectively suppressing a rise in battery temperature during charging and discharging. This also gives
It is possible to provide a method of manufacturing a module battery capable of efficiently performing initial charging and discharging of a unit cell.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a structure of a unit cell used in an example of the present invention.

FIG. 2 is a perspective view showing a structure of a module battery used in the example.

FIG. 3 is a cross-sectional view of a main part showing a state of a joint of the unit cells of the module battery.

FIG. 4 is a longitudinal sectional view showing a structure of a cooling device used in the embodiment.

FIG. 5 is a characteristic diagram showing a relationship between a charge amount and a battery temperature in the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 unit cell 2 battery case 3 lid 4, 5 pole 6 rib 9 safety valve 10 module battery 11 end plate 12 connecting member 13 space portion 14 connecting member 19 waterproof cap 20 cooling device 21 inner tank 22 outer tank 23 cooling water supply part 23a Hole 25 Coupling member 26 Chiller 27 Supply pipe 28 Discharge pipe

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noriyuki Fujioka 555 Sakaijuku, Kosai-shi, Shizuoka Prefecture Inside Panasonic Eve Energy Co., Ltd. (72) Inventor Munehisa 555 Sakaijuku, Kosai-shi, Shizuoka Prefecture Inside Panasonic Eve Energy Co., Ltd.

Claims (7)

[Claims] 1. A method for cooling a module battery in which a plurality of unit cells are stacked, wherein the module battery includes a plurality of square unit cells having a plurality of ribs arranged vertically on a side surface of a battery case. A method for cooling a module battery, wherein ribs are abutted against each other, and wherein a liquid refrigerant flows through a space formed between the unit cells. 2. The cooling of the module battery according to claim 1, wherein the module battery is disposed in a tank containing the refrigerant so that an upper end of the rib is immersed in the refrigerant, and the refrigerant flows through the space. Method. 3. The method for cooling a module battery according to claim 2, wherein the refrigerant is supplied while overflowing the tank from the outside. 4. The method for cooling a module battery according to claim 1, wherein the cooling medium is circulated with the space facing upward. 5. The method according to claim 1, wherein the refrigerant is water. 6. The method for cooling a module battery according to claim 1, wherein the pole of the unit cell includes a shield member for preventing the attachment of the refrigerant. 7. A method for manufacturing a module battery in which a plurality of unit cells are stacked, wherein the initial charging and discharging of the unit cells are performed while cooling by the module battery cooling method according to claim 1. .