JPH09293500A - Manufacture of electrode plate for use in storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations of a thickness of an electrode plate so as to provide the uniform electrode plate of a high quality by linearly tapering an active material slurry filling electrode plate from the center toward both ends, followed by rolling by means of rolls having a radius at both ends smaller than that at the center. SOLUTION: Active material slurry serving as an electrode mixture is filled into a current collector of a band-like foamed nickel base having a width of 500mm, followed by drying, thereby forming a filling electrode plate 5. At this time, the foamed nickel base has a porosity of 95%, a thickness of 2mm and an active material filling density after rolling of 2.9g/cc. The filling electrode plate 5 is made to pass rolls 6, which is annealed in a depth of 10mm in radius from the surface, followed by rolling. Each of the pair of rolls 6 for rolling the filling electrode plate 5 while holding it therebetween has a diameter of 450mm at the center and a whole length of 600mm. Furthermore, the roll 6 is tapered linearly toward the both ends from the center, wherein a radius at both ends is less by 10μm than a radius at the center. Consequently, it is possible to remarkably reduce variations of a thickness of the fabricated electrode plate, thus efficiently manufacturing the electrode plate of a high quality having a uniform thickness.

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 an electrode plate used in a storage battery, and more particularly to a method of manufacturing an electrode plate by rolling a filled electrode plate having an electrode mixture adhering to a current collector with a roll. .

[0002]

2. Description of the Related Art A method of manufacturing an electrode plate by filling an electrically conductive current collector with an electrode mixture and rolling it with a roll is important in order to increase the packing density and increase the thickness of the electrode plate. To be uniform. When the thickness of the electrode plate is not uniform, for example, when the electrode plate is thicker than a predetermined value, the dimension becomes larger than the predetermined value when the electrode group is configured, which causes a problem that it cannot be inserted into the battery can. On the other hand, if it is thin, the packing density becomes too high, so that the permeability of the electrolytic solution deteriorates, and as a result, the battery life varies due to the variation in the amount of the electrolytic solution.

A technique for rolling the electrode plate to a uniform thickness is described in, for example, Japanese Patent Laid-Open No. 5-21055. The method described in this publication is that a current collector is filled with an electrode mixture containing an active material and a binder to form a filled electrode plate, and the filled electrode plate is passed between rolling rolls to obtain a uniform thickness. Have been rolled into. In order to increase the packing density of the electrode plate and to make the thickness uniform, the manufacturing method described in this publication is not shown in FIG.
As shown in (1), the filled electrode plate 5 is first rolled by the large-diameter rolling roll 1 and finally rolled by the small-diameter rolling roll 2 to form the electrode plate 4.

[0004]

The method described in the above publication is characterized in that the packing density can be increased by finally rolling with the rolling roll 2 having a small diameter. However, in this method, since the auxiliary roll 3 is disposed on the small-diameter rolling roll 2 and the auxiliary roll 3 presses the small-diameter rolling roll 2, the manufacturing apparatus becomes complicated. In addition, the gap between the small-diameter rolling rolls 2 is adjusted while the auxiliary roll 3 is in contact with the small-diameter rolling rolls 2.
There is a drawback that it becomes difficult to adjust the gap. In addition, if the auxiliary roll 3 cannot press the entire rolling roll 2 having a small diameter with a uniform pressure, the electrode plate 4 cannot be rolled to a uniform thickness.

Further, the electrode plate 4 manufactured by the method shown in FIG. 1 has the disadvantage that both sides are thinner than the central portion, so that the entire plate cannot be manufactured to have a uniform thickness.

[0006] The present invention has been developed for the purpose of further solving this drawback. An important object of the present invention is to provide a method of manufacturing an electrode plate used for a storage battery, which can roll the electrode plate to a uniform thickness with a very simple device.

[0007]

According to the method of manufacturing an electrode plate used in a storage battery of the present invention, an electrode mixture containing an active material and a binder is attached to a conductive current collector to fill the electrode plate 5. Is prepared, and the filled electrode plate 5 is rolled by a rolling roll 6 to obtain an electrode plate having a predetermined thickness, which is an improved manufacturing method.

Since the present inventors use an extremely thick metal rolling roll having a diameter of 450 mm for rolling the filled electrode plate, the gaps between the rolling rolls that pass through the filled electrode plate are uniformly maintained. I was convinced that the electrode plate that passed through was rolled to a uniform thickness. However, it was clarified that an error of several% in thickness occurs in the width direction when many electrode plates were actually manufactured and the thickness thereof was measured. Initially, the present inventors considered that the error in the thickness was due to the error in the thickness of the rolling roll, and accurately ground the surface of the rolling roll to make the outer diameter into a precise dimension with high accuracy. However, no matter how high the precision rolling roll is used to roll the filled electrode plate, it is not possible to reduce the variation in the thickness of the electrode plate to be manufactured in the width direction. The present inventors have been unable to determine the cause,
It was not possible to reduce the thickness error of the electrode plate in the width direction. However, for the rolling of the filled electrode plate, by using a rolling roll having a unique shape in which the thickness is partially different, instead of a rolling roll having the same thickness as a whole, the thickness of the electrode plate to be rolled is We succeeded in significantly reducing the error in the width direction.

Therefore, the method of manufacturing the electrode plate used in the storage battery of the present invention is characterized in that the rolling of the filled electrode plate 5 uses the rolling rolls 6 whose ends are gradually thinner than the central part. To do.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify a method for manufacturing an electrode plate used for a storage battery for embodying the technical idea of the present invention, and the present invention describes a method for manufacturing an electrode plate as follows. No specific method.

Further, in this specification, for easy understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as "the claims column" and "to solve the problems. It is added to the members shown in the column of "means". However, the members described in the claims are not limited to the members of the embodiments.

In the method for producing the electrode plate used in the storage battery of the present invention, the current collector is filled with an electrode mixture to obtain a filled electrode plate, and the filled electrode plate is rolled with a rolling roll to give a predetermined thickness. Manufactures electrode plates. The production method of the present invention does not specify the current collector and the electrode mixture of the electrode plate to be produced, but in the following, an implementation using a foamed nickel substrate as the current collector and an electrode mixture as the positive electrode mixture An example will be described in detail.

Example 1 [Step of Preparing Active Material Slurry as Electrode Mixture] The following powders (1) to (4) are added and mixed to prepare an active material slurry. 2.5% by weight of zinc and 1% of cobalt as coprecipitation components
90 parts by weight of nickel hydroxide powder containing wt% (average particle size measured by laser method is about 10 μm) 10 parts by weight of cobalt hydroxide 3 parts by weight of zinc oxide powder 50 parts by weight of a 0.2 wt% aqueous solution of hydroxypropyl cellulose Parts by weight

[Step of Filling Current Collector with Active Material Slurry as Electrode Mixture to Produce Filled Electrode Plate] The obtained active material slurry is a strip-shaped foamed nickel substrate having a width of about 500 mm. Fill an electric body and dry. The nickel foam substrate has a porosity of 95% and a thickness of about 2 mm. The filling amount of the active material slurry is such that the active material filling density after rolling is 2.9 g.
/ Cc.

[Step of rolling the filled electrode plate] As shown in FIG. 2, the filled electrode plate 5 is passed through a rolling roll 6 for rolling. The material of the rolling roll 6 is JIS SUJ-2,
It is quenched to a depth of about 10 mm from the surface of the roll. As shown in FIG. 3, the two rolling rolls 6 that sandwich and roll the filled electrode plate 5 have a diameter of 450 m at the center.
m, and the total length is 600 mm. Furthermore, rolling roll 6
Reduces the diameter linearly from the center toward both ends, and makes the radii at both ends 10 μm smaller than the radius at the center. The pressure with which the rolling roll 6 rolls the filled electrode plate 5 is adjusted so that the center portion in the width direction of the electrode plate to be rolled has a predetermined thickness.

(Embodiment 2) As shown in FIG. 3, the rolling roll 6 for rolling the filled electrode plate 5 has a diameter linearly reduced from the center toward both ends, and the radius of both ends is the radius of the center. An electrode plate is manufactured in the same manner as in Example 1 except that the electrode plate is made smaller by 20 μm.

(Embodiment 3) As shown in FIG. 3, the rolling roll 6 for rolling the filled electrode plate 5 has a diameter linearly reduced from the center to both ends, and the radius of both ends is the radius of the center. The electrode plate is manufactured in the same manner as in Example 1 except that the electrode plate is reduced by 30 μm.

(Embodiment 4) The rolling roll 6 for rolling the filled electrode plate 5 has a size of 200 m from both ends as shown in FIG.
The electrode plate is manufactured in the same manner as in Example 1 except that the diameter of the portion m is linearly reduced from the center toward both ends and the radius of both ends is smaller than the radius of the center by 10 μm.

(Embodiment 5) The dimension of the rolling roll 6 for rolling the filled electrode plate 5 is 200 m from both ends as shown in FIG.
An electrode plate is manufactured in the same manner as in Example 1 except that the diameter of the portion m is linearly reduced from the center toward both ends and the radius of both ends is smaller than the radius of the center by 20 μm.

(Embodiment 6) The dimension of the rolling roll 6 for rolling the filled electrode plate 5 is 200 m from both ends as shown in FIG.
An electrode plate is manufactured in the same manner as in Example 1 except that the diameter of the portion m is linearly reduced from the center toward both ends and the radius of both ends is smaller than the radius of the center by 30 μm.

(Comparative Example) As shown in FIG.
Of the rolling roll 6 for rolling
An electrode plate is manufactured in the same manner as in Example 1 except that the thickness is set to mm.

When the thickness of the electrode plate manufactured as described above is measured at intervals of 50 mm in the axial direction of the rolling roll,
The maximum value, minimum value, average value and standard deviation are shown in Table 1 below.

[0023]

[Table 1]

As shown in this table, Examples 1 to 1 of the present invention
The electrode plate manufactured by the method No. 6 has a very small standard deviation of 0.0008 to 0.0046 indicating the variation in thickness. On the other hand, the standard deviation of the electrode plate manufactured by the method of the comparative example was as large as 0.0104. The standard deviation of the electrode plate manufactured by the method of Example 2 was 0.0008, which was 1/10 or less of that of the comparative example.

Further, in the electrode plates of the comparative examples, the difference between the maximum thickness and the minimum thickness was about 5% of the total thickness, but the electrode plates manufactured in Examples 1 to 6 of the present invention were thick. The difference in thickness was 2% or less, and particularly the electrode plate manufactured in Example 2 was 0.5%, which was 1/10 of the comparative example.

Further, the thicknesses of the electrode plates manufactured in Examples 1 to 6 were measured at 25 mm intervals in the axial direction of the rolling roll, and the results are shown in graphs in FIGS. 6 and 7.
As is clear from these figures, the electrode plate manufactured by the method of the comparative example is thick in the central portion and thin at both end portions, but the electrode plate manufactured by the method of the example of the present invention is The thickness error between the central portion and both end portions was extremely small, and the thickness unevenness was reduced as a whole.

The method of manufacturing the electrode plate used in the storage battery of the present invention is a method for adjusting the thickness of the rolling roll, particularly the thickness of both ends, in consideration of the material of the electrode plate to be manufactured. The thickness error in the width direction of is minimized. To determine how thin the thickness of both ends of the rolling roll is compared to the central part, prototype a plate with a rolling roll that has the same overall diameter and measure the thickness of the plate in the width direction. Then you can easily guess.

For example, the electrode plate prototyped in the comparative example has a thickness of about 33 μm thinner on both sides as compared with the central portion.
In order to correct this thickness error, as shown in FIG. 8, the diameter of the rolling roll that presses both ends of the filled electrode plate is set to about 3 mm.
3 μm, that is, the radius is reduced by 33/2 μm. In other words, pressing the center of the electrode plate, which becomes thicker after rolling, narrows the gap between the central portions of the rolling rolls, and widens the gap at both ends of the rolling roll, where the electrode plate becomes thinner. The rolling roll 6 of FIG. 8 has a total length of 600 mm. With this rolling roll 6,
The filled electrode plate 5 having a width of 500 mm is rolled. Therefore, the rolling roll 6 rolls both end edges of the electrode plate at a position 250 mm from the center. The radius of this part is 33
Since the thickness is reduced to / 2 μm, it is necessary to reduce the thickness to about 20 μm at both ends of the rolling roll 6 which is 300 mm away from the center.

Example 2 shows that the radius of both ends of the rolling roll 6 can be reduced by about 20 μm to minimize the error in the thickness of the electrode plate. Therefore, the filled electrode plate is rolled with a rolling roll that makes the entire thickness the same to form an electrode plate, and the thickness of the center part and both end parts of this electrode plate is measured, and it can be rolled in an ideal state. The size of the roll can be easily estimated.

As shown in FIGS. 3 and 4, the above embodiment shows an embodiment in which two rolling rolls 6 for rolling the filled electrode plate 5 have the same shape. However, as shown in FIG. 9, the manufacturing method of the electrode plate used for the storage battery of the present invention is as follows.
One rolling roll 6 for rolling the filled electrode plate 5 may have the same thickness as a whole, and the other rolling roll 6 may be a taper roll having both ends thinner than the central portion. As shown in this figure, the method of rolling the filled electrode plate is such that the radius of the both ends of the taper roll is reduced as compared with the one using the rolls of the same shape as shown in FIGS. 3 and 4. To double (40 μm).

Furthermore, in the above-mentioned embodiment, the filled electrode plate 5 is rolled by using the rolling rolls 6 which linearly narrow the radius toward the end portion. However, the electrode plate of the present invention is manufactured. The method uses a rolling roll 6 whose radius decreases non-linearly toward the end as shown in FIG. 10 or a rolling roll 6 which becomes stepwise narrower toward the end as shown in FIG. Then, the filled electrode plate 5 can be rolled to produce an electrode plate.

[0032]

The method for producing the electrode plate used in the storage battery of the present invention is a method of using a unique shape of the rolling roll, which also uses a rolling roll having a slightly thin end. With a simple method, it is possible to significantly reduce the variation in the thickness of the electrode plate that is manufactured. In this way, the manufacturing method of the present invention, which can make the thickness of the electrode plate uniform, changes the rolling roll into a unique shape with almost no change in the conventional manufacturing method and apparatus, and is extremely uniform. A thick plate can be manufactured. Therefore, it is possible to realize the feature that high-quality electrode plates can be mass-produced at low cost. Further, since the electrode plate manufacturing method of the present invention can make the thickness of the electrode plate in the width direction uniform, a wide electrode plate is continuously manufactured, and the electrode plate is cut and assembled into a storage battery, Achieve the features that enable efficient and high-quality production of electrode plates.

[Brief description of drawings]

FIG. 1 is a side view showing a method for manufacturing an electrode plate by rolling according to a conventional method.

FIG. 2 is a perspective view showing a state where the filled electrode plate is rolled by a rolling roll according to the method of the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a rolling roll that rolls a filled electrode plate by the method of Examples 1 to 3.

FIG. 4 is a cross-sectional view showing a rolling roll that rolls a filled electrode plate by the method of Examples 4 to 6.

FIG. 5 is a sectional view showing a conventional method in which a rolling roll rolls a filled electrode plate.

FIG. 6 is a graph showing the thickness error in the width direction of the electrode plates manufactured by the methods of Examples 1 to 3 and Comparative Example.

FIG. 7 is a graph showing an error in thickness in the width direction of electrode plates manufactured by the methods of Examples 4 to 6 and Comparative Example.

FIG. 8 is a cross-sectional view showing a rolling roll used in the method of the embodiment of the present invention and showing dimensions for narrowing the end portion.

FIG. 9 is a sectional view of a rolling roll used in another embodiment of the present invention.

FIG. 10 is a sectional view of a rolling roll used in another embodiment of the present invention.

FIG. 11 is a sectional view of a rolling roll used in another embodiment of the present invention.

[Explanation of symbols]

 1 ... Large diameter rolling roll 2 ... Small diameter rolling roll 3 ... Auxiliary roll 4 ... Pole plate 5 ... Filled electrode plate 6 ... Rolling roll

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Oshita 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (1)

[Claims] 1. An electrode mixture containing an active material and a binder,
A filled electrode plate (5) is prepared by adhering to a current collector having conductivity, and the filled electrode plate (5) is rolled by a rolling roll (6) to form an electrode plate (7) having a predetermined thickness. In a method of manufacturing an electrode plate used for a storage battery, used for a storage battery characterized by using a rolling roll (6) whose end part is gradually thinner than the central part for rolling the filled electrode plate (5). Method for manufacturing an electrode plate.