JP2002164080A - Lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid insufficient charging of positive electrode plates which may shorten in an early stage service life of a lead-acid battery having equal numbers of positive and negative electrode plates. SOLUTION: A fine-mesh grating, which is formed by expanding a lead-alloy sheet comprising a Pb-Ca-Sn lead alloy with an Sb-containing thin film formed on each side thereof, is used as the positive electrode, and the negative electrode plates are wrapped with separators and bagged to constitute a group of electrode plates. The group of electrode plates has equal numbers of positive and negative electrode plates for each cell of the lead-acid battery.

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 provides a lead storage battery in which the cost, weight, and productivity of a product are reduced.

[0002]

2. Description of the Related Art A lead-acid battery using a Pb-Ca-Sn alloy for a lattice body is known as Pb-Sb-As, which was mainly used before that.
Compared to lead-acid batteries using alloys, they are widely used because they have features such as less electrolyte reduction and self-discharge and excellent storage characteristics. Further, a technique of forming a thin film containing Sn or Sb on the surface of a lattice body has been proposed in order to improve charge acceptability after overdischarge standing and cycle life characteristics of performing deep charge / discharge. On the other hand, in the configuration of a normal lead-acid battery, the number of negative plates is generally one more than the number of positive plates with respect to the number of positive plates. This is because the amount of negative electrode active material is increased by increasing the number of negative electrode plates, and the gas generation (polarization) at the negative electrode during charging is delayed by increasing the amount of negative electrode active material. In order to sufficiently charge the positive electrode plate. However, in recent years, in order to improve the energy density and weight of the battery, reduce the cost of the product and improve the productivity, the charge acceptability is improved even with a small amount of active material by increasing the additive of the negative electrode. There has been proposed a technology of a configuration in which the number of positive and negative plates is the same.

[0003]

However, in a lead-acid battery using a calcium-based alloy, if the number of positive and negative plates is the same, it is advantageous in terms of cost reduction and productivity, but the cycle under a certain condition is improved. It has become clear that the capacity is reduced in the service life and the service life is reached early. Furthermore, a separator made of a synthetic resin, which is widely used in recent years, generally has a shape in which the electrode plate is wrapped around in a bag shape in order to prevent an internal short circuit due to falling off of the active material. When the negative electrode plate is packed in a bag in a number of lead storage batteries, the life is more significantly reduced. The reason for this is that a lead-acid battery having a configuration in which a negative electrode plate is packaged has a smaller current value at the end of charging than a lead-acid battery in which a positive electrode plate is packaged, and in particular insufficient charging of the positive electrode plate is likely to occur.

[0004] The present invention is to solve the above problems,
An object of the present invention is to overcome the problems when the number of electrode plates is reduced and when the negative electrode plate is packed in a bag with a separator, and to suppress a decrease in the life of a lead storage battery.

[0005]

Means for Solving the Problems As means for solving the above-mentioned problems, the invention described in claim 1 of the present invention is as follows.
Pb-Ca-Sn-based lead-acid battery in which a grid body obtained by expanding a lead alloy sheet in which a thin film of an alloy containing Sb is formed on both surfaces of both surfaces is used as a positive electrode, and the number of positive and negative plates is equal. It is what it was.

[0006] The invention described in claim 2 is the invention according to claim 1.
In the described invention, the alloy containing Sb is a Pb-Sb-based alloy or a Pb-Sn-Sb-based alloy.

The invention according to claim 3 has the structure according to claim 1 or 2, wherein the negative electrode plate is wrapped with a bag-shaped separator.

[0008] The invention described in claim 4 is the first invention.
In the lead-acid battery having the configuration described in any one of (3) to (3), the opening area per square constituting the mesh part of the positive grid is made smaller than the opening area per square of the negative grid.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a grid used for a positive electrode plate of a lead-acid battery according to the present invention is formed by laminating a thin film of an alloy containing Sb on both sides of a continuous cast body of a Pb-Ca-Sn alloy. The lead alloy sheet integrated by cold rolling and cold rolling is expanded to form a mesh-like lattice as shown in FIG. After filling the active material paste into the meshes of the lattice, a positive electrode plate is obtained through an aging and drying process. The separator is a microporous polyethylene sheet, and forms an electrode group so as to enclose the negative electrode plate. From the separator in which the positive electrode plate and the negative electrode plate are packed in a bag, an electrode plate group having the same number of positive electrode plates and negative electrode plates as shown in FIG. 3 is obtained. The battery according to the configuration of the present invention eliminates the above-mentioned problems of early capacity reduction due to insufficient charging at the positive electrode during the life cycle and short-circuit between the positive electrode and the negative electrode due to separator breakage, and contributes to excellent life performance. It is. Furthermore, in order to obtain the effect of improving the insufficient charge of the present invention particularly remarkably, the amount of Sb contained in the Sb layer formed on the surface of the positive electrode lattice must be 2.0% by mass to 1%.
0.0% by mass, layer thickness 0.01 mm to 0.05 mm
It is preferable that

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the grid alloy of the lead-acid battery according to the present invention comprises Pb-0.07% by weight Ca-1.3% by weight Sn.
A Pb-Ca-Sn alloy sheet 1 having a thickness of about 0.2 mm and a Pb-Sb alloy sheet 2 having a thickness of about 0.2 mm Pb are superimposed on both surfaces of a continuous cast Pb-Ca-Sn alloy sheet 1 having a thickness of about 15 mm. Rolled by the rolling roller 3 produced a rolled lead sheet 4. The lead rolled sheet 4 is expanded to form a mesh as shown in FIG. 2, the active material paste is filled in grids formed by the mesh, and then cut into a single electrode plate to form a positive electrode plate. Was prepared. At this time, larger ones and the opening area of the opening area of about 2.5 cm ² squares constituting the mesh portion of the grid was prepared as small about 1 cm ^2. FIG. 2 shows the grids constituting the mesh portion of the lattice.

On the other hand, the negative electrode plate is made of Pb-0.07 mass% Ca.
A grid of approximately 0.8 mm, which is a -0.3 mass% Sn alloy, is rolled and expanded in the same manner as the positive electrode, and a grid is produced.
It was obtained by filling this with an active material paste. As the separators, two types of bag-shaped separators were prepared using a microporous polyethylene sheet having a thickness of about 0.3 mm to enclose the positive electrode plate or the negative electrode plate.

Each of the above two types of positive plates and a pair of positive plates packed in a separator are combined to form a positive electrode plate 5 per cell.
Plate group consisting of the same number of bipolar plates and five negative plates,
A 5D23 type lead acid battery for automobiles (12V48Ah) was manufactured. In FIG. 3, 6 indicates a positive electrode plate, 7 indicates a negative electrode plate, and 8 indicates a bag-shaped separator. Table 1 shows the opening areas of the grids of the grids of the positive and negative plates and the conditions for bagging by the separator.

Further, for comparison with the group C of the present invention, lead rolling was carried out by rolling a Pb-Sb alloy sheet 2 on only one side of a Pb-Ca-Sn alloy sheet 1 according to a conventional manufacturing method and similarly rolling. A sheet was prepared, and this lead rolled sheet was expanded to form a mesh-like lattice. As shown in Table 1, a lead-acid battery using this lattice body was produced under the same conditions as those of the present invention, and used as a lead-acid battery B group of a comparative example. further,
As shown in Table 1, a lead-acid battery in which the number of the negative electrode plates was increased by one was formed, and this was designated as a lead-acid battery A group of the conventional example.

[0015]

[Table 1]

The lead storage batteries having different configurations shown in Table 1 were evaluated by performing the following life tests in the following patterns. This life test is a test pattern assuming the use of a discharge tendency in which deep discharge enters. In the JISD5301 light load life test, discharge during a cycle was performed for 8 minutes and charging was performed for 16 minutes. Table 1 shows the test results.
The above-described life test evaluation was performed using a lead-acid battery A having a conventional configuration.
The life characteristics of the group were set to 100, and the lead storage batteries having the respective configurations were compared.

A comparative example, in which a lead storage battery A having a group configuration in which the number of negative electrode plates is one greater than the number of positive electrode plates and a configuration in which the number of positive electrode plates and negative electrode plates is the same as that of the conventional lead storage battery group A, is a feature. Comparing the lead storage battery B, the life characteristics of B are considerably lower than that of A.

Further, it can be seen that the batteries B and B in which the number of the positive electrode plates and the number of the negative electrode plates are the same and the separator encloses only the negative electrode plate have a markedly reduced life as compared with the conventional group A. This is because, when the number of the negative electrode plates is not larger than the number of the positive electrode plates, the charging reaction of the negative electrode active material having higher charging efficiency than the positive electrode at the time of constant voltage charging is completed, and the charging is terminated at the end of charging without sufficiently charging the positive electrode. Has reached
It is considered that this undercharge reaction was accumulated by repeating the cycle, and the life was shortened.

It is also considered that a separator in which only the negative electrode plate is packed is an important factor. Normal,
Since the volume expansion and lattice expansion due to the life cycle of the positive electrode plate give stress to the separator, it is ideal to pack only the negative electrode plate instead of packing the positive electrode plate with the separator. As can be seen from the result of the battery B having the same number of the positive electrode plate and the negative electrode plate when the plates are bagged with the separator, the insufficient charging of the positive electrode is more accelerated. This could be confirmed by the remarkable accumulation of lead sulfate in the positive electrode active material. Also, one of the lattice meshes like B or B
Although a slight improvement in service life was observed by improving the conductivity inside the electrode plate by using a grid in which the positive electrode was smaller than the negative electrode in the opening area per cell, the improvement in charging efficiency was incomplete. Was.

Group C, which is the lead storage battery of the present invention, is a lead storage battery having the same number of positive and negative plates as the lead storage battery of Group B, but the Group B is greatly deteriorated in life characteristics. In contrast, the life characteristics of the group C were slightly reduced. This shows that the effect of forming the Sb thin film on both surfaces of the positive electrode grid is great. By providing the Sb layer on both surfaces of the positive electrode grid, the charge acceptability of the positive electrode is improved and the positive electrode is sufficiently charged. It can be assumed that the accumulation of insufficient charging of the positive electrode, which has been performed, has been eliminated.

The effect of this is that as the cycle progresses, Sb elutes from the Sb layer on the surface of the positive electrode grid into the electrolytic solution, passes through the separator and deposits on the negative electrode, thereby lowering the hydrogen overvoltage (polarization) of the negative electrode. This is due to As a result, it is considered that the polarization of the positive electrode was increased, and the positive electrode could secure a sufficient amount of charged electricity, leading to an improvement in charging efficiency. By providing the Sb layer on both sides of the positive electrode grid, it can be said that the Sb action effect appears earlier than in the case where the Sb layer is provided only on one side, and at the same time, more Sb worked effectively.

Further, in order to pursue the effects of the Sb layers on both surfaces of the positive electrode, a life test was performed on a lead storage battery using a grid body in which the same amount of Sb layers was formed on only one surface as a positive electrode plate. The life characteristics were almost the same as those of the conventional lead storage battery group B having an Sb layer on one side, and only the amount of liquid reduction was increased. For this reason, the Sb action leading to the improvement of the life characteristics is not effective simply by increasing the Sb content in the Sb layer on the surface of the positive electrode grid, and is different from the case where the Sb layers are provided on both surfaces of the positive electrode. It can be said that it is important that the sulfuric acid interface be present on the lattice surface over a wide area. In addition, in the case of the lead storage batteries C and C in which the separator encloses only the negative electrode plate, the life of the lead storage battery provided with the Sb layer on one side was remarkably decreased, whereas the life of the lead storage battery provided with the Sb layer was marked on both sides.
It can be said that the life of the lead storage battery having the layer is slightly reduced, and there is no problem of insufficient charging of the positive electrode.

Next, a life test was conducted on the assumption that a lead storage battery is used due to an overcharge tendency, in addition to the life test in which deep discharge enters. This test condition is an overcharge life test in which 1 cycle of charging at 13.8 V for 120 hours in a 75 ° C. atmosphere is one cycle. The test results are also shown in Table 1. From the results shown in Table 1, it can be seen that the lead storage battery in which the separator encloses only the positive electrode plate has poor characteristics regardless of the lead storage batteries of the conventional example and the present invention. This is because the cycle of the positive electrode grid was extended by the cycle, a hole was formed in the bottom of the separator, and the positive electrode and the negative electrode were short-circuited, and the life was extended. On the other hand, the lead storage battery in which the negative electrode plate was wrapped by the separator exhibited good life characteristics without short circuit.

As described above, Sb is applied to both sides of the lead alloy sheet.
A lead-acid battery C composed of the same number of positive plates and negative plates in which a grid body having layers formed therein and having a small opening area of a grid constituting a grid mesh portion is used as a positive electrode, and a negative electrode is packaged with a separator. In both the deep discharge test pattern and the overcharge test pattern, it was found that among the lead storage batteries having the respective configurations, particularly excellent life characteristics were exhibited.

[0025]

As described above, a positive electrode plate per cell is used in a positive electrode plate group in which a mesh-like lattice body obtained by expanding a lead alloy sheet having a Pb-Ca-Sn lead alloy and Sb thin films formed on both surfaces thereof on both sides is expanded. The lead storage battery of the present invention having the same number of negative electrode plates and negative electrode plates can have excellent overcharge life characteristics while preventing early capacity reduction due to insufficient charging of the positive electrode in a deep discharge cycle. The present invention has a great effect that leads to cost reduction and productivity improvement.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing steps of a lead alloy sheet of a positive electrode.

FIG. 2 is a front view showing a grid of electrode plates;

FIG. 3 is a perspective view showing a partial cross section showing the configuration of an electrode plate group;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pb-Ca-Sn alloy sheet 2 Pb-Sb alloy sheet 3 Rolling roller 4 Lead rolling sheet 5 Square 6 Positive electrode plate 7 Negative electrode plate 8 Bag-shaped separator

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Yoshihiro Murata Inventor 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term (reference) in Matsushita Electric Industrial Co., Ltd. CC08 EE01 HH05

Claims (4)

[Claims] A lead alloy sheet formed by superimposing and rolling a thin film of an alloy containing Sb on both surfaces of a cast body of a Pb—Ca—Sn alloy; A lead-acid battery comprising a group of electrode plates having the same number of positive and negative electrode plates per cell. 2. The lead-acid battery according to claim 1, wherein the alloy containing Sb is a Pb-Sb-based alloy or a Pb-Sn-Sb-based alloy. 3. The lead-acid battery according to claim 1, wherein the negative electrode plate is wrapped in a microporous bag-shaped separator mainly composed of a synthetic resin. 4. The negative electrode grid according to claim 1, wherein an opening area per square constituting the mesh portion of the positive grid is smaller than an opening area per square of the negative grid. Lead storage battery.