JPH11354112A - Electrode plate for lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of a problem at the formation or at the dis charging and thereby provide an electrode plate having initial performance excellent in stability, by coating surfaces of the electrode plate with a thin film and providing pass-through parts in the thin film. SOLUTION: An expanded sheet is made by forming a net-like expanded part in a continuous band-like rolled sheet by an expanding machine. When the expanded sheet is introduced into a filling machine, paper is simultaneously introduced thereinto under the expanded sheet, and after the net-like expanded part is filled with a paste-like active material comprising lead powder and dilute sulfuric acid, the paper is stuck over an upper surface of the paste. After roll-pressed by rollers, the expanded sheet is cut to a fixed size to make electrode plates. Half of the electrode plates are provided with pass-through parts 13 in portions 12 on one side thereof where the paper is relatively easily peeled off. By using the electrode plate as an electrode plate for a lead-acid battery, insufficient formation due to gas accumulation at the time of the formation and hindered diffusion of water or sulfuric acid at the time of discharging can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an electrode plate for a lead storage battery.

[0002]

2. Description of the Related Art At present, lead-acid batteries are used in various fields including those for automobiles and industries, and further cost reduction is required. Conventionally, a cast grid made by gravity casting has been used as a grid body in a lead-acid battery, but an expanded grid has been used for cost reduction. As shown in FIG. 1, the expanded lattice is a lattice body including an upper forehead 1 which is a non-expanded portion and an expanded portion constituted by a large number of rhombic cells 4 formed by nodes 2 and ridges 3. . The expanded lattice is a lattice body produced by expanding a rolled sheet made of a lead alloy and is excellent in productivity. Therefore, the cost can be reduced as compared with the casting grid.

[0003] However, the expanded lattice has a large rhombic cell constituting the developed portion and has no picture frame on both sides, so that the active material may fall off during production. It is common practice to coat the electrode surface with a thin film when or after filling the active material into the lattice.

After filling, the expanded electrode plate is dried,
Although the electrode plate surface and the thin film are easily separated from each other at the center of the electrode plate after the drying, a phenomenon in which the electrode plate is firmly adhered to the upper, lower, and both side edges is observed. The reason for this is not clear, but is presumed as follows.

[0005] One of the problems in the production of the expanded grating is that the expanded portion is warped during the expanding process. This warpage is usually corrected by a guide or a roll press. However, since this correction is insufficient, a relatively large pressure is applied to the upper and lower portions of the electrode plate by the roll press after filling, which causes the thin film and the electrode plate to adhere firmly. In addition, when cutting the electrode plate after the roll pressing, a relatively large pressure is applied to both end portions, which causes the thin film and the electrode plate to firmly adhere to each other.

Next, a battery is assembled using the positive electrode plate, and after dilute sulfuric acid is injected, the battery case is formed. At that time, the following reaction occurs in the positive electrode plate. Theoretically, (a), (b),
Although only the reaction (c) occurs, the reaction (d) occurs simultaneously as a competitive reaction. (A) PbO + H
₂ SO ₄ → PbSO ₄ + H ₂ O (b) PbSO ₄ + 2H ₂ O → PbO ₂ + H ₂ SO ₄
^{+ 2H + + 2e - (c} ) PbO + H 2 O → PbO 2 + 2H + + 2e - (d) H 2 O → 1 / 2O 2 + 2H + + 2e - oxygen gas generated here can not easily diffuse in the film . In addition, oxygen gas accumulates between the surface of the electrode plate and the thin film because the electrode plate and the thin film are firmly adhered to each other at the top, bottom, and both ends of the electrode plate. With the progress of chemical formation,
Due to the permeation of the sulfuric acid aqueous solution into the thin film and the buoyancy of the oxygen gas rising in the liquid, the thin film and the electrode plate surface of the relatively weakly adhered portion of the thin film at the upper end are separated. After that, the gas gradually passes through the separated part,
The accumulated oxygen gas decreases.

[0007]

However, since the generation of oxygen occurs continuously during chemical formation, this gas pool always exists unless the above-mentioned thin film peeling occurs over a wide area. This gas reservoir impedes the diffusion of sulfuric acid and water into the plates,
Suppress the chemical reaction. As a result, there is a problem in that the amount of lead dioxide in the gas reservoir is reduced with a normal amount of conversion electricity, resulting in poor initial performance.

[0008] In a battery having a structure in which the distance between the electrode plates is narrow, the tendency is more remarkable because the range of the gas reservoir portion is increased. Furthermore, since the peeling between the thin film and the surface of the electrode plate occurs irregularly, there is also a problem that the initial performance varies greatly and a battery with stable performance cannot be supplied.
Increasing the amount of formation electricity to solve this problem increases the amount of electricity used for the decomposition reaction of water, resulting in an increase in the amount of reduction in the electrolytic solution and an excessive formation in portions where formation has normally progressed. When the current flows, the active material softens,
It could cause another problem of dropout.

At the time of discharging, P generated by formation or charging
bO ₂ reacts as follows.

(E) PbO ₂ + H ₂ SO ₄ + 2H ⁺ +2
e ⁻ → PbSO ₄ + 2H ₂ O, that is, diffusion of sulfuric acid into the electrode plate and diffusion of water into the bulk must occur promptly. Normally, paper soluble in sulfuric acid is used as the thin film, but it remains undissolved for a certain period of time after chemical formation, which inhibits the diffusion of sulfuric acid and water. Therefore, there is a problem that the initial discharge characteristics are inferior.

Here, the above-mentioned problem does not occur unless the thin film is used. However, a thin film is usually indispensable for the expanded lattice, and in order to eliminate the need for the thin film, the rhombic cells in the expanded portion are extremely finely divided. In addition, picture frames must be provided at both ends. However, in the former case, the grid weight increases, which leads to an increase in battery weight and cost. If the increase in the grid weight is suppressed, the ridges become thinner and the grid strength is reduced, which adversely affects the life performance. Further, many methods for providing a frame at both end portions on the latter side have been devised, but none of them is practical. Therefore, even when a thin film is used, there has been a demand for an electrode plate for a lead storage battery which does not cause the above-described problems during formation and discharge and has stable and excellent initial performance.

[0012]

The lead plate for a lead storage battery according to the present invention is characterized in that the thin film covering the surface of the plate has a penetrating portion.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An electrode plate for a lead storage battery according to the present invention has a thin film covering the surface of the electrode plate having a penetrating portion.
By using such an electrode plate, even if gas is generated from the electrode plate during chemical formation, it does not form a gas reservoir, has excellent chemical conversion properties, and does not hinder the diffusion of sulfuric acid and water during discharge and is stable and excellent. A lead storage battery having improved initial performance can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 2 shows a manufacturing process of filling the expanded lattice with the paste-like active material. (A) is its top view, (b) is its side view, 5 is a development sheet, 6 is a filling machine, 7 is paper, 8
Denotes a roller, 9 denotes an electrode plate cutting machine, and 10 denotes an electrode plate.

First, a continuous strip-shaped rolled sheet made of a lead-calcium-tin-based alloy and having a thickness of 1.1 mm was prepared, and this was used to form a net-like developed portion as an active material holding portion by an expanding machine. . Next, a paste-like active material obtained by kneading lead powder and dilute sulfuric acid was filled in the net-like developed portion by a filling machine. At this time, the surface of the electrode plate is covered with a thin film. As the thin film, a paper having a thickness of about 30 μm and containing pulp as a main component and soluble in sulfuric acid was used.

As shown in FIG. 2, when the spread sheet 5 is introduced into the filling machine 6, the paper 7 is simultaneously introduced into the lower surface of the spread sheet 5. Further, after filling, the paper 7 is attached to the upper surface of the paste. Next, in order to make the thickness of the electrode plate uniform and to make the surface of the electrode plate smooth, roll pressing was performed by the roller 8. The spread sheet filled with the paste-like active material was cut into a predetermined width by the electrode plate cutting machine 9.

As described above, the electrode plate 10 having both sides covered with paper was produced. The paper supply method differs depending on the filling machine. Here, a method in which the paper is supplied to the lower surface of the spread sheet before filling and the upper surface is supplied after filling has been described. However, there is a filling machine in which both upper and lower surfaces are pasted after filling.

The obtained positive plates were stacked 50 by 50 to form a block, and the paste-like active material was dried. After drying, the paper stuck to the positive electrode plate was firmly adhered to the top, bottom, and both ends of the positive electrode plate as shown in FIG. Numeral 11 indicates this strongly adhered portion. As shown in FIG. 3B, a half of the positive electrode plate was provided with a slit 13 at a central portion 12 on one side of the positive electrode plate where the paper was relatively easily peeled off, as shown in FIG. That is, two types of electrode plates were prepared, a positive electrode plate having a slit in the paper and a positive electrode plate having no slit.

Using each of the above-mentioned electrode plates and a normal negative electrode plate, 55 liquid type batteries each having a capacity of about 55 Ah were manufactured. Here, the negative electrode plate was placed in a bag-shaped microporous polyethylene separator. These batteries were formed in a battery case under ordinary conditions, and were discharged at a rate of 5 hours (final voltage: 1.70 V / cell). FIG. 4 shows the results. The electrode plate provided with the slit had a larger initial battery capacity and less variation than the electrode plate provided with no slit.

Further, when each battery was disassembled after forming five battery containers and the positive electrode plate was observed, the positive electrode plate provided with slits was formed uniformly and sufficiently, while the positive electrode plate provided with no slit was provided. It was confirmed that white spots were observed in the upper part of the electrode plate where the paper was easily peeled off, and that the part was in an insufficiently converted state.

In this embodiment, the description has been made of the electrode plate having a portion penetrating through the paper on one side of the electrode plate. However, if this penetrating portion is provided on both sides, a battery having a larger initial capacity and a small variation can be obtained. Needless to say. In addition, the present invention does not define the shape of the penetrating portion, has a function of preventing the active material from falling off during manufacturing, and if the diffusion of gas or the like is not hindered, for example, FIGS. The same effect can be obtained even with the shape shown in d). Needless to say, a mesh or mesh structure may be used.

Furthermore, although the positive electrode plate has been described here, the same negative paper as the positive electrode plate inhibits the discharge reaction. Therefore, if a penetrating portion is provided, a battery having a large initial capacity and a small variation can be obtained. Obtainable.

In this embodiment, the case where a paper soluble in sulfuric acid is used as the thin film has been described. However, various thin films can be used by using the present invention. For example, even in the case of a thin film insoluble in sulfuric acid such as a synthetic thin film or a glass fiber thin film, the advantage that the charge / discharge reaction becomes uniform can be obtained.

[0024]

As described above, according to the present invention, even when a thin film for an electrode plate of a lead storage battery is used, insufficient formation due to gas accumulation during formation and diffusion of water and sulfuric acid during discharge are possible. A lead plate for a lead-acid battery having excellent stable initial performance can be obtained without causing a problem such as obstruction of the lead-acid battery.

[Brief description of the drawings]

FIG. 1 shows the shape of an expanded lattice body.

FIG. 2 is a diagram showing a manufacturing process for filling an expanded lattice body with a paste-like active material.

FIG. 3 is a diagram showing a shape of a penetrating portion of a thin film.

FIG. 4 is a distribution diagram of the initial discharge capacity of the product of the present invention and the conventional product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper forehead 2 Sections 3 Jewel 4 Cell 5 Deployment sheet 6 Filling machine 7 Paper 8 Roller 9 Electrode plate cutting machine 10 Electrode plate 11 Strongly adhered part 12 Easy peeling part 13 Penetrating part

Claims (1)

[Claims] 1. A lead-acid battery electrode plate in which the surface of the electrode plate is covered with a thin film, wherein the thin film has a penetrating portion.