JP2002075380A - Expand grid body for lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expand grid for a lead-acid battery having superior mechanical strength and hardly deformed. SOLUTION: The minimum curvature radius of a shape of a part surrounded by a frame, which is formed by the development of the expand grid for the lead-acid battery manufactured by developing a lead alloy sheet, is set to 0.1 mm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a lead storage battery, and more particularly to an improvement in the life performance of a lead storage battery using an expanded grid.

[0002]

2. Description of the Related Art At present, a method for producing a grid for a lead-acid battery is as follows.
The casting method or the expanding method has become mainstream.

[0003] An advantage of the casting method is that a frame (hereinafter referred to as a frame) surrounding the periphery of the grid can be formed, which can form a grid of an arbitrary shape including a shape having a small electric resistance. For example, it is possible to make a grid that is difficult to deform. Disadvantages are poor productivity due to the batch type, difficult to make an integrated line connected to the subsequent process such as paste, and difficult to cast in the case of low strength alloy such as lead-calcium alloy. There are things.

[0004] On the other hand, in the expanding method, a lead alloy sheet produced by rolling or the like is developed to form a mesh grid. There are two main types of unfolding systems: a rotary system that cuts the sheet with a blade that rotates on the sheet and simultaneously forms a mesh, and a reciprocating system that cuts the sheet with a V-shaped blade that moves up and down and simultaneously forms a mesh. is there. Both can be manufactured continuously, and a consistent line can be set up from the paste filling and drying process.
It has the feature of extremely high productivity compared to the casting method. Further, even with a lead-calcium alloy or a lead-calcium-tin alloy, a lead alloy sheet can be easily produced. Disadvantages are that the grid shape that can be formed by expansion is limited to some extent, and that the grid cannot be formed with a vertical frame, resulting in poor mechanical strength and easy deformation. In particular, when used for a positive electrode grid of a lead-acid battery, Pb on the grid surface changes to PbO _{2 having} a large volume, so a tensile force is applied to the grid, and the grid is likely to elongate and deform.

[0005]

In the conventional expanded lattice, at any corner of a diamond-shaped portion surrounded by a bar formed by expansion, a portion having an inner radius of curvature close to 0 (a point of a sharp split). Because of this, stress corrosion caused by the change of Pb on the lattice surface to PbO _{2 having} a large volume in this portion is promoted, easily deformed in the vertical direction, and the battery life is shortened early. There is a point.

[0006]

SUMMARY OF THE INVENTION The present invention provides an expanded grid that can suppress deformation of the grid even when used in a lead-acid battery and improve the life performance. That is,
The expanded lattice body for a lead storage battery according to the present invention is configured so that the minimum radius of curvature of the shape inside the portion surrounded by the bar formed by expansion is 0.1 mm or more. When the sheet is developed into a lattice shape, of the blade portion that cuts the sheet, the vicinity of a portion that cuts the sharpest part of the lattice opening is cut and developed by using an R-shaped blade. Alternatively, it is characterized in that it is punched into an elliptical shape as a slit formed in a lead alloy sheet, and is developed and processed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the expanded grid for a lead-acid battery according to the present invention, the minimum radius of curvature of the shape inside the portion surrounded by the bars is set to 0.1 mm or more. When the sheet is developed into a lattice shape, of the blade portion that cuts the sheet, the vicinity of a portion that cuts the sharpest part of the lattice opening is cut and developed by using an R-shaped blade. By the above or by developing a slit punched into an oval as a slit formed in the lead alloy sheet, the minimum radius of curvature is 0.1
mm or more. If the minimum radius of curvature is 0.1 mm or more, regardless of the grid expansion method,
It is possible to provide an expanded grid that can suppress deformation of the grid and improve life performance.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the expanded grid for a lead storage battery according to the present invention will be described below.

Most of the life of a battery using an expanded grid is due to deformation of the positive grid, and therefore various studies have been made on a grid structure to prevent this.

[0010] The present invention and a conventional expanded grating are:
As shown in the schematic views of FIGS. 1 and 7, a grid development part (net-like part) 5 formed by developing a lead sheet is provided below the upper frame 4. Reference numeral 6 denotes a rhombus portion formed in the developed portion, and reference numeral 7 denotes a portion provided with a circular arc on the inner surface of the rhombus portion. FIG. 2 is an enlarged view of the grid developing section in FIG. 1, and FIG. 8 is an enlarged view of the grid developing section in FIG. Since the radius of curvature of the portion of the normal expanded grid surrounded by the bar formed by deployment is substantially zero, when the grid is corroded in this portion, stress corrosion occurs and the grid is easily deformed. .

[0011] In order to confirm the effect of suppressing the deformation of the expanded lattice, a test was performed by changing the radius of curvature of the corner after the expansion of the expanded lattice. In addition, we examined the difference in the effect of preventing spread due to the difference in deployment method.

In order to examine the performance of these grids, an automobile battery (36B20, 12V, 28A) as shown in the schematic diagram of FIG.
h / 5hR) were prepared and tested. In FIG.
Is a collecting ear, 2 is a strap, and 3 is a connection portion between cells.
Hereinafter, a method for manufacturing the lattice and the battery will be described.

[0013]

[Table 1]

Battery No. Nos. 1 to 4 are for comparing the minimum radii of curvature of the corners. Reference numerals 4 and 5 are for comparing manufacturing methods.

The alloy composition of the lead sheet used for the expanded lattice of the positive electrode is Pb-0.06 wt% Ca-1.5 wt
% Sn, the alloy composition of the lead sheet for the negative electrode is Pb-0.06
wt% Ca-0.5wt% Sn. Each was produced by a cold rolling method, and the thickness was 1.1 mm for the positive electrode and 0.7 mm for the negative electrode. The amount of Ca in the lead sheet is 0.1
It is generally known that, when the amount is less than about 2 wt%, the tensile strength increases as the amount of Sn increases up to about 2 wt%. The reason why the amount of Sn and the thickness of the lead sheet for the positive electrode are increased is to increase the strength and corrosion resistance of the sheet.

These lead sheets were formed into slits having the shape shown in FIG. 4 so that the shape after development became rhombic, or punched into an oval shape as shown in FIG. 5, and then developed to form a lattice. . The minimum radius of curvature of the diamond after the development was changed by changing the minimum radius of curvature of the oval to be punched. In addition, No. In the grid used for the battery of No. 5, the sheet in which the slit shown in FIG. 4 was generated was developed with a blade having the shape shown in FIG. In the figure, reference numeral 8 denotes an R-shaped portion of the developing blade.

When the sheet is left at room temperature, its strength increases by age hardening within several days to several tens of days after production.
In general, it is known that processing before completion is better in strength and corrosion resistance than processing after completion of age hardening, but this tends to cause strain when processing with increased strength That's why. For this reason, development was completed within 5 days after sheet production.

In an actual lattice, an accurate rhombus is not formed due to a point of intersection or a cutting tool, but these are considered to be substantially rhombic.

Both surfaces of the lead sheet have been roughened by brushing before development. In general, since the surface of a rolled sheet is smooth, the adhesiveness between the grid and the active material becomes poor when the rolled sheet is used as an electrode plate. By performing the surface roughening treatment, the adhesion is improved, and an expanded lattice from which the active material is less likely to fall can be obtained.

The expanded grid was filled with a general paste for automotive lead-acid batteries, and aged in a usual manner to produce a positive electrode plate. A general negative electrode plate was also used.

Next, the positive electrode plate was placed in a bag-shaped microporous polyethylene separator. Ribs are formed on the inner side, which is the surface in contact with the positive electrode plate. The separator was formed by folding a polyethylene sheet in two and pressing both sides by a pair of gears. In this case, the positive electrode plate is placed in the bag-shaped separator, but the negative electrode plate may be placed in such a case so that the ribs are on the outside.

Five positive plates and six negative plates placed in a separator
The elements were alternately overlapped to form an element, and the six elements were inserted into a battery case, then connected between cells, and the lid was welded to obtain a battery. Inject sulfuric acid as electrolyte into this battery,
The battery case formation was performed by a usual method. The specific gravity of the electrolytic solution after the formation was 1.280.

Next, these batteries were subjected to a high temperature overcharge life test. The battery was placed in a 75 ° C water bath,
Continuous energization was performed for 0 days. A comparison was made between the 5-hour rate capacity after the completion of the energization and the initial 5-hour rate capacity (the initial capacity was set to 100), and the deformation of the positive electrode plate was measured. Table 2 shows the results
It was shown to.

[0024]

[Table 2]

Battery No. 1 using a conventional positive electrode expanded grid was used. In No. 1, the positive electrode plate was significantly deformed and short-circuited.
Battery No. Although some deformation was seen in 2, 3, and 4,
No short circuit was observed.

In a normal expanded lattice, the minimum radius of curvature of the portion surrounded by the bar formed by the expansion is substantially zero, so that when stress is applied, corrosion occurs at the portion where the radius of curvature is minimum. While it was severely deformed easily in the vertical and horizontal directions, the product of the present invention had a minimum radius of curvature of 0.
Since it was 1 mm or more, deformation in the vertical and horizontal directions was structurally suppressed.

From these results, if the minimum radius of curvature of the portion surrounded by the crosspiece formed by the unfolding has a minimum radius of curvature of 0.1 mm or more, the deformation of the electrode plate can be suppressed, thereby improving the battery performance. I understood.

[0028]

As described in detail above, according to the present invention, a battery having excellent life performance can be obtained even when an expanded lattice is used, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic view of an expanded grating according to the present invention.

FIG. 2 is an enlarged view of a grid developing unit in FIG. 1;

FIG. 3 is a schematic diagram of a battery.

FIG. 4 is a view showing a shape of a slit formed in a lead alloy sheet.

FIG. 5 is a view showing a shape of a slit formed in a lead alloy sheet.

FIG. 6 is an explanatory view of a developing blade for developing a lead sheet.

FIG. 7 is a schematic view of a conventional expanded grating.

FIG. 8 is an enlarged view of a grid developing unit in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current collection ear 2 Strap 3 Connection part between cells 4 Upper frame 5 Grid development part (net-like part) 6 Diamond part 7 Part provided with arc 8 R shape part

Continuation of the front page (71) Applicant 500413294 Masao Sakane 27-2, Kamigamo Higashigoto-cho, Kita-ku, Kyoto-shi, Kyoto 2 (72) Inventor Megumi Ameyama 4-4 Seiwa-cho, Otsu-shi, Oga, Shiga Prefecture (72) Inventor Japan Shimo Takayuki 1-9-30 Asahigaoka, Otsu City, Shiga Prefecture (72) Inventor Masao Sakane 27-2, Goto-cho, Kamigamo Higashi, Kita-ku, Kyoto-shi, Kyoto, Japan 2 (72) Inventor Ken Sawai Nishino, Kichijo-in, Minami-ku, Kyoto, Kyoto Shoinobamabacho No. 1 Nippon Battery Co., Ltd. F-term (reference) 5H017 AA01 BB07 BB14 BB19 CC07 EE02 HH03

Claims (3)

[Claims] 1. An expanded grid body for a lead-acid battery manufactured by developing a lead alloy sheet, wherein a minimum radius of curvature of a shape inside a portion surrounded by a crosspiece formed by the expansion is 0.
An expanded lattice body for a lead storage battery, which is 1 mm or more. 2. A blade which cuts the lead alloy sheet into a grid shape when cutting the sheet at the sharpest angle of the grid opening is formed into an R-shape. The expanded lattice body for a lead-acid battery according to claim 1, which is obtained by cutting and expanding the same. 3. The expanded lattice body for a lead storage battery according to claim 1, wherein the expanded lattice body is obtained by punching and developing an elliptical shape as a slit formed in a lead alloy sheet.