JPH0737606A - Manufacture of thin lead-acid battery - Google Patents

Abstract

PURPOSE:To provide a thin lead-acid battery with high capacity and long cycle life by realizing an active material producing no cracks in aging and drying processes. CONSTITUTION:A positive active material 2 is printed on the surface of an interdigital positive current collector 1 and a negative active material 3 on the surface of an interdigital negative current collector 3. A semi-completed part 5 is put into a square plastic box 6, which is treated for preventing air and drying, in aging and drying processes, and a front door 7 is closed, then the box 6 is placed in a constant temperature-constant humidity container 8 controlled at, for example, 50 deg.C-95%RH for 2 days. Then the semi-completed part 5 is moved to a plastic box, similar to the above plastic box, placed in a constant temperature-constant humidity container controlled at 25 deg.C-90%RH for one day. The plastic box, in which the semi-completed part 5 is put, is taken out of the constant temperature-constant humidity container, and placed in a constant temperature-constant humidity container controlled at 25 deg.C-35%RH for 4 days for aging and drying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin lead acid battery having high capacity and long life.

[0002]

2. Description of the Related Art A conventional thin lead-acid battery (JP-A-1-132)
No. 064), a foil-shaped positive and negative comb-shaped current collectors are fixed to face each other on the same surface inside a rectangular sheet upper case substrate. The active material is formed by a screen printing method, etc., and then subjected to general aging / drying treatment and chemical conversion treatment, followed by washing with water /
After drying, each gap between the two active materials facing each other is filled with an electrolyte, and the other similar case having the function of a lid and the above-mentioned case substrate are overlapped and the peripheral part is sealed by thermocompression bonding. Manufactured as a finished product.

In order to increase the capacity of the thin lead acid battery by using the current collector having the same shape and size as the conventional one, it is necessary to further increase the thickness of the active material layer. The thick coating method of the active material is shown in Japanese Patent Application No. 2-403209 by the present applicant. The semi-finished product, in which the active material is thickly coated on the surface of the comb-shaped current collector, is immediately transferred to the drying step called the next aging. The main purpose of the aging / drying process is to completely release the pre-mixed water when forming the active material on the surface of the current collector without causing cracking of the active material or peeling / falling off from the current collector. In addition, by combining substances such as lead oxide and lead sulfate in the active material with oxygen in a dry atmosphere to change them to substances such as water-containing basic lead sulfate, and increase the binding force between particles of the substance. Or to increase the adhesion between the substance and the current collector.

As a conventional aging / drying method, the semi-finished product is dried by leaving it in a constant temperature and humidity chamber kept at a temperature of room temperature to 85 ° C. and a humidity of 50 to 95% RH for several days. Heating / humidifying drying method, heating / drying method for drying for several days in a constant temperature bath kept at several tens of degrees Celsius in the air, normal temperature,
A natural drying method in which the surface of the active material is left to stand in normal humidity for 10 or more days to be dried, or dilute sulfuric acid or ammonium sulfate is applied to the surface of the active material immediately after printing, or it is immersed in these solutions for a short time to form cracks on the surface of the active material. After forming a difficult film,
There has been a solution treatment / drying method for performing any one of the above drying treatments. However, neither method is effective for semi-finished products in which the active material is thickly coated on the surface of the comb-shaped collector,
A problem that cracks frequently occur in the active material occurs, which has been a fundamental obstacle that significantly reduces the manufacturing yield of the battery when it is a finished product. These cracks are randomly generated at the base of the comb-shaped active material and in the direction perpendicular to the lengthwise direction of the stripe-shaped active material, and some of them have a crepe shape and reach the surface of the current collector. Was given.

Such cracks generated in the aging / drying process deteriorate the adhesion between the current collector and the active material.
Not only will this cause a major hindrance to handling, but the probability that the active material will be peeled off or dropped off from the current collector during subsequent chemical conversion treatment will also increase, and when assembled as a battery, the initial capacity will vary greatly. It had a drawback that satisfactory results could not be obtained. Further, during practical use, the active material expands and contracts with the progress of charging and discharging, so that the active material peels and falls off from the current collector more and more, which is a fatal drawback of extremely short life.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a thin lead acid battery having a high capacity and a long life, which enables elimination of the above-mentioned drawbacks to realize an active material free from cracks during aging and drying. With the goal.

[0007]

According to the present invention, an active material is applied on the surface of a lead or lead alloy current collector fixed to a case substrate to form a positive electrode and a negative electrode, and an electrolyte is provided between both electrodes. In the method for manufacturing a thin lead acid battery with the interposition of, the active material for the positive electrode and the negative electrode is applied on the surface of the current collector, and then aged.
It is characterized in that the positive electrode and the negative electrode are formed by performing heating and humidification in the drying stage and then gradually lowering the temperature and humidity of the atmosphere in each step.

[0008]

According to the present invention, after the active material is applied on the surface of the comb-shaped current collector, the temperature and humidity of the atmosphere during the aging and drying of the active material are gradually lowered to evaporate the water in the active material. By delaying it compared with the conventional method, it is possible to realize an active material that does not crack during aging and drying.

[0009]

EXAMPLES Examples of the present invention will be described below. Example 1 A positive electrode active material 2 having a thickness of about 2 mm was provided on the surface of the positive electrode comb-shaped current collector 1 shown in FIG. 1, and a negative electrode having a thickness of about 1.5 mm was provided on the surface of the negative electrode comb-shaped current collector 3. The semi-finished product 5 on which the active material 4 is printed is first subjected to the aging / drying step.
In the case of -1, it was placed in a square plastic box 6 which was subjected to windproof and dryproof treatment shown in FIG. 2, the front door 7 was closed, and this was controlled at a constant condition of, for example, 50 ° C. and 95% RH. It was placed in a constant temperature and constant humidity tank 8 and left for 2 days. The semi-finished product 5 in this case is obtained by laying a thin cloth 10 impregnated with deionized water on each surface of a net-shaped shelf plate 9 made of stainless steel and provided in a plastic box 6 at several stages at equal intervals. Two pieces were arranged on each stage in the central portion on the upper side. For the plastic box 6 (hexahedral), 44 holes 11 each having a diameter of 2 mm were formed on each surface at regular intervals, as holes 11 having a diameter of 2 mm. By using such a plastic box 6, the direct influence on the active material of the wind generated by the rotation of the stirring motor used to keep the temperature and humidity in the constant temperature and humidity chamber 8 uniform is reduced. Further, by arranging the wet cloth 10 on each shelf 9, rapid aging and drying of the positive electrode active material 2 and the negative electrode active material 4 can be avoided.

Next, in STEP-II, 25 ° C., 90%
The semi-finished product 5 was transferred into a previously prepared plastic box similar to the above into a constant temperature and humidity chamber kept under RH conditions, and left for 1 day. In the plastic box in this case, a semi-finished product 5 was placed on the surface of the plastic box without using a water-containing thin cloth and using only the same shelf plate as above. further,
In the final STEP-III, the plastic box containing the semi-finished product 5 was taken out from the constant temperature and humidity chamber of STEP-II and placed in the constant temperature and humidity chamber kept at 25 ° C and 35% RH for 4 days. It was left to stand, aged and dried to complete the whole process. The results obtained by the above method for a total of about 30 semi-finished products 5 were very good, with no cracks being observed in any of the positive electrode and negative electrode active materials 2 and 4.

FIG. 3 shows an example of changes over time in the weight of the active material in the semi-finished product 5 according to this method. As is clear from this figure, STEP- in this method (1)
Approximately + 1% / 2 days at 1 (50 ° C, 95% RH), STE
About -2% / 1 day for P-II (25 ° C, 90% RH) and about -8 for STEP-III (25 ° C, 35% RH).
% / 4 days, and the change in weight with time shows a gradual decrease.

[Embodiment 2] Final STE by this method (1)
About 20 semi-finished products 5 were aged and dried in the same manner as in Example 1, with P-III being one day. The results are shown as the present method (2), and an example of changes over time in the weight of the active material at this time is also shown in FIG. As is clear from FIG. 3, in this case also, STEP-I to STEP
Up to −III, the weight change of the active material shows a gradual decrease tendency. The rate of change in STEP-III was about -9% / day. There were no cracks in the semi-finished product 5 even by the method (2).

Comparative Example In the conventional method (1), the semi-finished product 5
Was aged and dried in an atmosphere of constant conditions of 65 ° C. and 90% RH. As shown in FIG. 3 above, the change with time in weight shows a sharp decrease until 5 hours, reaches about −11% at that time, and then gradually increases thereafter. In the conventional method (2), the results of aging and drying under the constant conditions of 25 ° C. and 90% RH are similarly shown, and in this case as well, the change with time in weight tends to decrease drastically. It shows about -10% at the lapse of time, and then gradually increases.
The conventional method has obtained the result that cracks frequently occur in all cases. As described above, the present methods (1) and (2) can reduce the decrease in water content in the active material with time during the aging / drying treatment more slowly than the conventional methods (1) and (2). As a result, it was possible to completely prevent the frequent occurrence of cracks that occurred in any of the conventional methods.

On the other hand, the above plastic box 6 is left to stand at room temperature, and the semifinished product 5 is placed on the water-containing thin cloth 10 on the shelf 9 in the box 6 in the same manner as described above, and then placed in the box 6. By supplying a moistened oxygen gas and controlling the flow rate thereof, the humidity in the vicinity of the semi-finished product 5 is changed to STEP-I (25 ° C., 95% RH, 2 days), as in the above case.
STEP-II (25 ℃, 90% RH, 1 day) and ST
Even with the method of gradually reducing it to EP-III (25 ° C., 35% RH, 1 day), the result that the occurrence of cracks can be completely eliminated is obtained. Further, even when the temperature and humidity are divided into 4 STEP or more from the atmosphere of 65 ° C. and 95% RH, and the temperature and humidity are gradually lowered to aging and drying, the result that cracks are not generated at all is obtained. As described above, when the positive and negative electrode active materials 2 and 4 are aged and dried, the temperature and humidity gradual drying method described above is applied, so that no cracks are generated in the positive and negative electrode active materials 2 and 4. I was able to

Under the conditions of the present method (1), aging and drying treatments were carried out, followed by chemical conversion treatment, and as shown in FIG. 1, each gap between the two active materials 2 and 4 facing each other was filled with the electrolyte 12,
The film case 13 having the function of a lid and the case substrate 14 of the semi-finished product 5 were superposed and the peripheral portion was sealed by a thermocompression bonding method to complete 30 thin lead acid batteries. When the batteries produced in this manner were evaluated, a good initial capacity was obtained in which all the batteries sufficiently satisfied the designed values. Furthermore, the total number of charge / discharge cycle life characteristics is 300.
Even after the cycle, the initial capacity was maintained at 50% or more (end of life), and extremely good results were obtained. On the other hand,
The 15 batteries that were aged and dried under the conditions of this method (2) and manufactured and evaluated by the same method as above all satisfied the design value of the initial capacity, and the charge and discharge cycle life characteristics The rate of change in capacity after 300 cycles
In all cases, extremely good results of 50% or more were obtained.

[0016]

As described above, the method for manufacturing a thin lead-acid battery of the present invention can significantly improve the yield during the aging / drying treatment of the active material and during the chemical conversion carried out immediately thereafter. It has the advantage of being effective. Further, the present invention is more useful than a conventional thin lead acid battery for a battery in which an active material is formed thick, and thus has a very great advantage that a thin lead acid battery having a high capacity and a long life can be realized. There is.

[Brief description of drawings]

FIG. 1 is a perspective view of a semi-finished battery for explaining the method of the present invention, as seen from the upper surface direction.

FIG. 2 is a schematic front view of a plastic box according to an embodiment of the present invention.

FIG. 3 is a diagram showing a comparison of changes in weight of an active material obtained according to the present invention and a weight of the active material obtained by a conventional method over time.

[Explanation of symbols]

1 is a positive electrode current collector, 2 is a positive electrode active material, 3 is a negative electrode current collector, 4 is a negative electrode active material, 5 is a semi-finished product, 6 is a plastic box, 7 is a front door, 8 Is a constant temperature and humidity chamber, 9
Is a shelf board, 10 is a wet cloth, 11 is a vent, 12 is an electrolyte, 13 is a film case, and 14 is a case substrate.

Front page continuation (72) Inventor Tsutomu Ogata 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Toshio Horie 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Nihon Telegraph Telephone Co., Ltd. (72) Shinji Saito, Shinji Saito, Shinjuku-ku, Tokyo 1-1-1 Shinshinto Electric Co., Ltd. (72) Inventor, Hayakawa, etc. No. 1 in Shinjin Todenki Co., Ltd. (72) Inventor Akio Komaki 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Inside Shinjindo Denki Co., Ltd.

Claims (1)

[Claims] 1. A thin lead storage battery in which an active material is applied to the surface of a current collector made of lead or a lead alloy fixed to a case substrate to form a positive electrode and a negative electrode, and an electrolyte is interposed between both electrodes. In the manufacturing method, the active material for the positive electrode and the negative electrode is applied on the surface of the current collector, and heating and humidification are performed at the stage of aging and drying, and then the temperature and humidity of the atmosphere are gradually decreased in each step. A method of manufacturing a thin lead-acid battery, characterized in that a positive electrode and a negative electrode are formed by going forward.