JPS5987755A - Paste-type lead storage battery - Google Patents

Abstract

PURPOSE:To improve the initial performance and life performance of a lead storage battery by making a glass mat that is made of glass fiber of 3mu or less in diameter and is provided with a number of permeation holes contact the surface of a positive electrode plate and combining the positive electrode plate with a negative electrode plate, pressing them, and forming the lead storage battery. CONSTITUTION:A porous body 3 with the degree of air ventilation of 20-200cc/ cm<2>.sec is made to contact both ends of a positive electrode plate 1 by providing a number of permeation holes 5 in a glass mat made of glass fiber of 3mu or less in diameter and in a porous body with a small hole diameter such as synthetic resin unwoven fabric. In addition, a paste-type lead storage battery is formed by combining the positive electrode plate with a negative electrode plate 2 through a separator 4 and housing them in a container while pressing the surface of the positive electrode plate 1 at a force of 30-120kg/cm<2>. As a result, the positive electrode plate 1 is pressed uniformly and the softening and slipping off of an active material can be prevented. Simultaneously, the diffusion of an electrolyte is improved and the life performance is also improved without reducing the discharge capacity of the plate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of a paste-type lead-acid battery, and an object of the present invention is to provide a lead-acid battery that has excellent initial performance and good life performance.

The lifespan of paste-type lead-acid batteries is generally determined by the lifespan of the positive electrode plate, and factors that cause deterioration of the positive electrode plate include shedding and softening of the positive electrode active material due to structural changes in the active material during charging and discharging, and corrosion of the grid. . Therefore, in order to improve life performance, it is necessary to prevent the positive electrode active material from softening or falling off, and to use a lead alloy with good corrosion resistance. However, corrosion of lead alloy grids occurs more when the active material falls off and the bare grid is exposed, that is, when it comes into direct contact with the electrolyte and is oxidized, than when the grid is covered with active material. Since this is more severe, it is important to first prevent the cathode active material from softening, falling off, or otherwise collapsing.

Conventional paste-type lead-acid batteries have a structure in which a glass mat made of glass fiber with a diameter of approximately 19μ is in contact with the positive electrode plate, so the electrode plate gradually expands due to structural changes in the active material layer during charging and discharging. At the same time, as the bonding force between the PbO2 particles decreases, the active material easily penetrates into the large gaps and pores between the glasses. The active material that has penetrated between the glass fibers has a poor electrical connection with the electrode plate body, so the effectiveness of the active material gradually begins to deteriorate and the material falls off, reaching the end of its life.

For this reason, a porous material such as a glass mat made of thinner glass fibers or a woven or non-woven fabric made of synthetic resin with a dense microstructure is brought into contact with the surface of the paste-type positive electrode plate to prevent the active material from penetrating or falling off. Proposals have been made to prevent this, and it has been confirmed that it actually improves life performance. However, such a method does not prevent the structural change of the active material, which is the essential cause of softening and falling off, and therefore it has not been possible to significantly improve the life performance.

On the other hand, as a method for essentially preventing structural changes in the active material, a method is known in which the surface of the positive electrode plate is uniformly pressed. This method uniformly presses the surface of the positive electrode plate to suppress changes in the microstructure due to expansion and contraction of the active material during charging and discharging, thereby preventing a decrease in the bonding force between PbO2 particles and extending the lifespan of the positive electrode plate. This is an attempt to improve performance.

The important point in this method is whether or not the surface of the positive electrode plate can be pressed uniformly. In fact, when a conventional glass mat is pressed against the positive electrode plate, the fiber diameter of the glass mat is thick and the mesh of the glass mat is wide, so it cannot be pressed evenly. It begins to soften and fall off, and the effect of pressing is not fully exerted. However, dense porous bodies with small pores, for example 3μ in diameter,
When a glass mat made of glass fiber or a nonwoven fabric or woven fabric made of synthetic resin is brought into contact with the positive electrode plate and pressed, the life performance is significantly improved.

This is because the surface of the positive electrode plate is pressed uniformly, which prevents it from softening and falling off, and at the same time prevents the active material from penetrating into the porous body. However, this method has the disadvantage that the amount of discharge is significantly reduced. This is because a porous body with a small pore diameter that has poor electrolyte diffusion is in contact with the positive electrode plate, and presses the surface of the positive electrode plate, which further inhibits electrolyte diffusion. Therefore, in a paste type lead-acid battery having a structure in which the surface of the positive electrode plate is compressed, it is particularly necessary to take care so that the diffusion of the electrolyte solution is not inhibited by the porous body itself that comes into contact with the positive electrode plate. As a measure of the quality of diffusion of the porous material itself,
Generally, a value called air permeability is adopted. This value is usually J
According to this method, the air permeability of a 1 mm thick glass mat made of glass fibers with a diameter of 3 μ or less is 1.0-10 cc/cm. sec.

Compared to the air permeability of a conventionally used glass mat made of glass fibers with a diameter of 19 μm, this value is extremely small.

As mentioned above, this means that a glass mat made of glass fibers with a diameter of 3 μm or less significantly inhibits the diffusion of the electrolyte and reduces the discharge capacity.

The present invention is intended to eliminate the above-mentioned drawbacks in paste type lead-acid batteries in which a porous body with a small pore diameter, that is, a porous body with poor air permeability, is pressed against a positive electrode plate. is 20~200cc/cm・see
By adjusting it so that the electrolyte can diffuse well, the life span can be significantly improved without reducing the discharge capacity.

Next, one embodiment of the present invention will be described in detail. Figure 1 shows the basic constituent units of the elements of a paste-type lead-acid battery. (1) is a positive electrode plate, (2) is a negative electrode plate, and (3) is a diameter of 3 μm.
A glass mat with a small pore diameter made of the following glass fibers is brought into contact with the positive electrode plate (1).

(4) is a severator. The glass mat (3) has a diameter of 02 to 2,0 as shown in Figure 2 and (II).
A through hole (5) of mm is formed in advance.This through hole (51
is formed by punching the glass mat (3) or pressing it with a roll provided with needle-like protrusions, and is provided so that the air permeability is 20-200 cc/cmsec. An element having such a structure is prepared by a known method, for example, by pressing rigid resin plates against both sides of the element with a force of 30 to 120 #/I1,
After attaching the positive and negative electrode straps, etc., the element is made by tying the resin plate together with a polypropylene or polyethylene band, and then inserted into the battery case. After that, a battery case lid is attached and chemical formation is performed to complete the paste type lead-acid battery according to the present invention.

The discharge amount and life performance of the present research crystal (Δ) obtained in this way, the conventional paste type lead-acid battery (B), and the 10+ battery in which a porous body with a small pore size without through holes is pressed against the positive electrode plate. A comparison is shown in Table 1. For comparison, the performance of a conventional paste type lead-acid battery (B) is 100%.
It is expressed as a ratio.

As seen in Table 1, the air permeability of the porous body is 20 to 2.
The 5hR capacity of the product (A) of the present invention, which is adjusted to 00cc/cm・sec, is almost the same as that of the conventional product, and the lifespan is approximately twice that of the conventional product. There is almost no decrease in life performance.

In addition, in the product of the present invention, the air permeability is set to 20 to 200 cc/
The reason for limiting C-sec is that below that, the electrolyte cannot diffuse well and the discharge capacity decreases, and above that the effect of uniformly pressing the positive electrode plate is lost. This is because the life performance does not improve. In addition, in this example, through holes are provided as a method of adjusting the air permeability, but by using glass mats with large pore diameters, the air permeability can be adjusted by reducing the thickness of the porous body. It's okay. Furthermore, in this example, a case was described in which a glass mat made of glass fiber with a diameter of 3μ or less was used as the porous body in contact with the positive electrode plate, but of course, even when a porous body made of synthetic resin with a small pore diameter is used, the air permeability can be improved. 20~200cc/cm・sec
The effect of the present invention is the same if the adjustment is made to .

As described above, according to the present invention, the life performance of the electrode plate can be precisely improved without substantially reducing the discharge capacity of the electrode plate, and its industrial value is extremely high.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the basic constituent units of the element of the paste-type lead-acid battery according to the present invention, and Figure 2 (1) is an enlarged plan view of a glass mat made of glass fiber with a diameter of 3 μm or less. FIG. 2(II) is an enlarged cross-sectional view taken along line A-A in FIG. 2(1). (1)...Positive plate, (2)...Negative plate, (3)...Glass mat, (4)...
・Separator, (5)...Through hole,

Claims (1)

[Claims] A porous body with a small pore diameter, such as a glass mat made of glass fiber with a diameter of 3μ or less, a woven fabric made of synthetic resin, or a non-woven fabric, is arranged so as to come into contact with the surface of the positive electrode plate, and
A lead-acid battery in which the surface of the positive electrode plate is pressed with a force of kg/dm, characterized in that the permeability of the porous body is adjusted to 20 to 200 cc/cm・scc by providing through holes in the porous body. Paste type lead acid battery.