JPH0782876B2 - Thin lead acid battery manufacturing method - 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 thin lead acid battery having a long life and a high capacity.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 1-132064 discloses a thin lead-acid battery by the present applicant. This thin lead acid battery is of an electrode parallel type in which a comb-shaped positive electrode plate and negative electrode plate are arranged on the same plane.

In such a conventional thin lead-acid battery, foil-shaped positive and negative comb-shaped current collectors are made to face each other on the same surface inside a rectangular sheet-shaped case substrate while keeping a predetermined distance therebetween. After fixing, form the positive electrode and negative electrode active materials on the surface of each current collector by, for example, the screen printing method, then perform general aging treatment and chemical conversion treatment, wash with water and dry, and then between both active materials facing each other. Fill the space with electrolyte with another similar shaped case that has the function of a lid and the above case substrate, and then seal the peripheral parts of both case substrates by thermocompression bonding. It is manufactured by the method.

[0004]

By the way, in order to increase the capacity of a thin lead-acid battery using a current collector having the same shape and size as the conventional one, it is necessary to form the active material thicker. Conventionally, when it is attempted to print an active material thicker than ever on a current collector by screen printing, it is technically extremely difficult to thicken the material of the screen mask and increase its pattern accuracy. For some reason, thick coating of the active material was not feasible.

As an alternative method, a method using a so-called metal mask in which a pattern is opened in a flat metal having a thickness comparable to that of the active material to be printed has been used. However, when an active material is printed on the surface of a current collector using such a metal mask, the thickness of the active material is generally larger than the width of the current collector. When removed, the active material locally adheres to the inner wall of the pattern opening. For this reason, printing defects such as missing parts, spots and irregularities of the active material often occur on the surface of the current collector, which causes a significant decrease in manufacturing yield.

In addition, when the initial characteristics and the life characteristics of a battery assembled through a predetermined manufacturing process are evaluated in the state where such a printing defect occurs, in many cases, unsatisfactory results are obtained. The poor condition was the fundamental obstacle.

Further, as a method for improving defective printing of the active material, a method of printing after adjusting the water content and the viscosity of the active material has been used. However, even this measure has not been sufficiently effective to suppress the occurrence of print defects.

On the other hand, as a method for solving this problem, the width of the comb-shaped current collector is made wider than that of the conventional one, and the adhesion of the active material to the surface of the current collector is increased to the inner wall of the pattern opening of the metal mask. A method of forming the active material only on the surface of the current collector by making it stronger than the adhesion of the active material is conceivable, but when it is completed as a thin lead acid battery, there is a drawback that the area becomes large.

An object of the present invention is to solve the above-mentioned technical problems and to manufacture a thin lead storage battery capable of forming an active material having a shape accurately reproducing the opening shape of a pattern opening of a mask on a current collector. To provide a method.

[0010]

In order to achieve the above-mentioned object, a method of manufacturing a thin lead-acid battery of the present invention comprises an active material on a lead or lead alloy current collector fixed to a case substrate. In a method for manufacturing a thin lead-acid battery in which a positive electrode plate and a negative electrode plate are closely adhered to each other and an electrolyte is filled between the both electrode plates, a mask having an opening portion having the same planar shape as the current collector is formed. A step of stacking the active material on the current collector and rubbing the active material on the current collector through the opening of the mask; and a convex portion having the same planar shape as the current collector on the mask. A pressing jig is overlapped and the convex portion of the pressing jig is pressed against the active material in the opening portion of the mask, and the pressing jig is applied with a downward load to form the case substrate. At least one of the masks away from the other It is moving, characterized in that it comprises a step of die-cutting the active material from the opening of the mask.

[0011]

In the present invention, the active material is rubbed on the current collector through the opening of the mask superposed on the current collector, and then the convex portion of the pressing jig superposed on the mask is removed. The active material is pressed against the surface of the active material, and in a state where a downward load is applied to the pressing jig, at least one of the case substrate and the mask is moved in a direction away from the other, so that the active material is opened in the opening portion of the mask. The active material having a thickness comparable to the thickness of the mask can be quickly and surely stamped from the thick mask opening to form it on the current collector. It is possible to prevent defects and improve the adhesion of the active material on the current collector.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, as shown in FIG. 1, a negative electrode current collector having the same shape and the same material as the positive electrode current collector 2 made of lead or lead alloy is formed on the main surface of a sheet-like case substrate 1. The body 3 and the body 3 are fixed so as to face each other while keeping a predetermined distance. Here, as the case substrate, those having various structures can be used, but it is preferable that the surface of the case substrate which is in close contact with the current collector is a polypropylene layer satisfying thermocompression bonding. In particular, considering the strength required for thin storage battery products and the ability to block water vapor, the case substrate is made of polypropylene, polyethylene terephthalate, polyvinylidene chloride, aluminum, etc. It is preferably a structure.

Next, as shown in FIG. 2, a negative electrode metal mask 5 having a pattern opening 4 having the same shape and dimensions as the planar shape and dimensions of the negative electrode current collector 3.
Are superposed on both current collectors 2 and 3 so that the pattern openings 4 and the negative electrode current collector 3 are aligned with each other. The thickness of the metal mask 5 is about 1.6 mm in this embodiment, but is not limited to this.

Next, the negative electrode active material 6 is formed on the metal mask 5.
Then, the negative electrode active material 6 is rubbed on the negative electrode current collector 3 through the pattern opening 4 of the metal mask 5 using the spatula 7 for printing. Pattern opening 4 of metal mask 5
The negative electrode active material other than that rubbed through the metal mask 5
From the surface of the.

Next, as shown in FIG. 3, the negative electrode active material 6 is demolded from the metal mask 5 using a pressing jig 8. As shown in the plan view of FIG. 4 and the perspective view of FIG. 5, the pressing jig 8 in this embodiment is provided with a flat plate-shaped jig body 9 and a lower surface of the jig body 9 and a negative electrode current collector. The pressing convex portion 10 has the same planar shape and dimensions as those of No. 3 and a handle portion 11 provided at the center of the upper surface of the jig body 9.

First, the pressing die convex portion 10 of the pressing die jig 8 is formed.
The bottom surface of the negative electrode active material 6 rubbed into the pattern opening portion 4 of the metal mask 5 so that the pressing jig 8
Load downwards against. While maintaining this state, the position of the case substrate 1 is fixed and the metal mask 5 is pushed upward, whereby the negative electrode active material in the pattern opening 4 is die-cut from the pattern opening 4. Then
By removing the pressing jig 8 and the metal mask 5, the negative electrode active material 6 having a thickness of about 1.6 mm is formed on the surface of the negative electrode current collector 3.

Next, as in the case of the metal mask 5 for the negative electrode, as shown in FIG. 6, a pattern opening 12 having the same shape and size as the planar shape and size of the current collector 2 for the positive electrode is formed. After stacking the formed positive electrode metal mask 13 having a thickness of about 2 mm on the positive electrode current collector 2,
By placing the positive electrode active material 14 on the metal mask 13 and performing the same procedure as in printing the negative electrode active material 6, the positive electrode active material having a thickness of about 2 mm is formed on the surface of the positive electrode current collector 2. 14 is formed, and the printing is completed.

As the material of the pressing jig 8 used here, a transparent acrylic resin is suitable. This jig 8
The size of each part is determined by the capacity of the thin storage battery to be manufactured. In this embodiment, the push-type convex portion 10 has a width of about 1.8 mm, a height of about 3 to 40 mm, and a length of about 40 mm.
Is. The weight to be applied to the pressing jig 8 is 35 to 60 g
It is preferably in the range of / cm ² . Further, by sticking a Teflon-based film on the entire surface of the pressing die convex portion of the pressing die jig 8 of this example or by applying wax to the inside of the pattern opening portion of the metal mask, the metal mask, the active material and the pressing die It is possible to improve the so-called mold release between the convex tip and the active material.

As described above, by using the pressing jig as described above at the time of printing the active material, the active material is completely free of defects, spots, and abnormal shapes, and the defective rate at the time of printing is almost zero. We were able to.

After printing under these conditions, followed by general aging and chemical conversion treatment, washing with water and drying, the electrolyte was placed in the space between the two active materials 6 and 14 facing each other as shown in FIG. 15 is injected, and finally, the other similarly shaped case substrate 16 having a lid function and the case substrate 1 are overlapped, and the peripheral portions of both cases 1 and 16 are sealed by thermocompression bonding. Complete a thin lead-acid battery.

When the thin lead-acid battery thus manufactured was evaluated, the initial capacity was a good value satisfying the design value. A charge / discharge test was conducted to examine the life characteristics of the capacity. As a result, after 140 cycles, 50% or more of the initial capacity (life end point) was maintained and extremely stable results were obtained. On the other hand, after performing the printing process without using the pressing jig as described above, the life characteristics of the capacity of the conventional thin lead acid battery assembled as a battery through a predetermined process were examined. After 30 cycles, the capacity decreased to 50% or less of the initial capacity.

The charging / discharging conditions were 2.40 V constant voltage charging, 100 mA current limitation, 10 hours charging, 1 hour rest after charging, 200 mA discharge current and 1.75 V final discharge voltage.

In the above embodiment, the pattern jig 4 or 12 of the metal mask 5 or 13 is formed by the pressing jig 8.
When the negative electrode active material 6 or the positive electrode active material 14 is die-cut from the case, the case substrate 1 is fixed and the metal mask 5 or 13
Was pushed upward, but on the contrary, while fixing the metal mask 5 or 13 and pushing down the pressing jig 8,
The case substrate 1 may be lowered downward. Furthermore, the active material 6 or 14 may be die-cut from the pattern opening 4 or 12 of the metal mask 5 or 13 by moving both the case substrate 1 and the metal mask 5 or 13 in a direction away from each other.

Further, in the above-mentioned embodiment, an example of the method of manufacturing the thin electrode storage battery of the electrode parallel type in which the positive electrode plate and the negative electrode plate are arranged on the same case substrate is shown. It is also possible to apply the present invention to a method of manufacturing an electrode laminated type which is arranged on different case substrates.

[0026]

As described above, according to the present invention,
Since the active material can be quickly and reliably die-cut from the pattern opening portion of the mask having a desired thickness, printing defects can be prevented, and thus the yield at the time of printing the active material can be remarkably improved, which is extremely effective. There is an advantage. Further, according to the present invention, since a thicker mask can be used than the conventional thin lead acid battery, it is possible to increase the amount of the active material, and it is possible to realize a thin lead acid battery having a high capacity and a long life. Also has

Further, according to the present invention, since the die can be removed from the mask while pressing the active material on the current collector by the pressing die, the adhesion of the active material on the current collector can be improved. It is also possible to prevent the active material from falling off during long-term use.

[Brief description of drawings]

FIG. 1 is a plan view showing one step in one embodiment of the present invention.

FIG. 2 is a plan view showing a metal mask for a negative electrode used in the present invention.

FIG. 3 is a partial cross-sectional front view showing a step of die-cutting an active material according to an embodiment of the present invention.

FIG. 4 is a plan view showing a pressing jig used in the present invention.

5 is a perspective view showing the pressing jig shown in FIG. 4. FIG.

FIG. 6 is a plan view showing a metal mask for a positive electrode used in the present invention.

FIG. 7 is an exploded perspective view showing a final assembling step in one embodiment of the present invention.

[Explanation of symbols]

 1 sheet-shaped case substrate 2 positive electrode current collector 3 negative electrode current collector 4 pattern opening of metal mask for negative electrode 5 metal mask for negative electrode 6 negative electrode active material 7 spatula for rubbing active material 8 push-type jig 9 jig body 10 push-type convex part 11 handle part 12 pattern opening of metal mask for positive electrode 13 metal mask for positive electrode 14 positive electrode active material 15 electrolyte 16 sheet-like case substrate having a lid function

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinori Hasuda 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (56) Reference JP-A-2-199771 (JP, A)

Claims (1)

[Claims] 1. A thin lead-acid battery in which a positive electrode plate and a negative electrode plate are formed by closely adhering an active material onto a lead or lead alloy current collector fixed to a case substrate, and an electrolyte is filled between both electrode plates. In the manufacturing method, the mask having an opening having the same planar shape as that of the current collector is overlaid on the current collector, and the active material is provided on the current collector through the opening of the mask. A step of rubbing and a pressing jig having a convex portion having the same planar shape as that of the current collector are superposed on the mask, and the convex portion of the pressing jig is overlapped with the opening portion of the mask. While pressing the active material, at least one of the case substrate and the mask is moved in a direction away from the other while the downward load is applied to the pressing jig to move the active material to the opening of the mask. Characterized by including a step of die-cutting from Method for manufacturing thin lead acid battery.