JPS6388753A - Cathode plate of lead storage battery - Google Patents

Abstract

PURPOSE:To improve a discharge capacity by using polyolefin type synthetic pulp sheets, which are addition polymerized with a multifunctional hydrophilic monomer, as an inner-layer material of a cathode plate or a surface-layer material of the cathode plate. CONSTITUTION:By coating with a paste-like active substance 3 containing lead oxide and sulfuric acid on both sides and holding at a pressed state from both sides, an inner-layer material 2 with sandwich structure adhering to a grid type skeleton 1 made of lead is prepared. Since the inner-layer material 2 is made of polyethylene synthetic pulp sheets with hydrophilic treatment, sulfuric acid solution-holding properties thereof are extraordinarily excellent and effective as an electrolyte supplying source structure. Also, this fibrillated pulp structure and the hydrophilic treatment improve the adhesion with paste as well as the liquid holding properties, which increases availability of the inner-layer material.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention Industrial Application Field The present invention relates to an anode plate for a paste type lead-acid battery.

Conventional technology and its problems The anode plate of a paste-type lead-acid battery is made by coating a lead lattice frame with a paste-like active material whose main components are lead oxide, sulfuric acid, and water. However, in low rate discharge, there is no problem because the discharge capacity is determined by the active material, but in high rate discharge where the discharge current is large, the discharge capacity is significantly reduced.

The reason for this is that in high-rate discharge, the rate of sulfuric acid diffusion is limited, and the discharge capacity is limited by the amount of sulfuric acid inside and near the electrode. It is required to be done.

As a means to improve this, for example, increasing the amount of sulfuric acid or water in the paste, or using a foaming agent to make it porous, are being considered, but highly porous electrodes tend to fall off more easily and have a shorter cycle life. This results in a drawback.

As a method to solve these drawbacks,
No. 373 is disclosed.

In this Japanese Patent Application Laid-Open No. 56-91373, a non-woven fabric or woven fabric is first combined with a lattice-like skeleton, and a paste-like active substance is applied to both surfaces of the lattice-like skeleton, and the non-woven fabric or woven fabric is used as the inner layer material of the anode plate. By burying it, the liquid retention of sulfuric acid is improved and the supply of electrolyte to the interior is increased.

However, Japanese Patent Application Publication No. 1983. In the published patent No. 91373, glass fiber or polyester #a is used as the material for the non-woven fabric or woven fabric, and these have insufficient wood affinity, poor liquid retention, and poor paste adhesion. inferior,
This cannot be said to be a satisfactory electrolyte supply structure.

On the other hand, in the anode plate of a lead-acid battery, a paste-like active material is applied to the lattice-like framework, and a protective film is provided on the surface of the active material in order to protect the active material from expansion/contraction or softening. Although the technology has existed for a long time,
When the water in the paste-like active substance is removed, gaps are created between the paste and the protective film, resulting in poor adhesion and the active substance falling off.
It has the disadvantage of causing leakage.

As a means to solve this problem, JP-A-60-1406
No. 51 is disclosed.

In JP-A-60-140651, the above problem is solved by interposing a woven or non-woven fabric between the active substance and the protective film.

In other words, by using a woven fabric or non-woven fabric made of the same material as the resin frame used as part of the lattice frame as the surface layer material of the active substance, and providing a protective film on this surface, the bonding with the frame is good and the fiber layer The elasticity protects the surface of the active substance under pressure, improves adhesion, prevents gaps from forming, and prevents the active substance from falling off or flowing out.

However, in this Japanese Patent Application Laid-Open No. 60-140651, polyethylene nonwoven fabric is mainly used because it is a nonwoven fabric of the same quality as the resin frame, and it has poor wood affinity and poor wettability, so it has ion diffusivity and φ electric resistance. becomes a negative factor,
Due to its battery properties, it cannot be said to be completely satisfactory.

The object of the present invention is to provide a polyolefin-based synthetic valve sheet such as polyethylene, which is a fiber sheet suitable for the above-mentioned anode plate inner layer material and the above-described anode plate surface layer material, and which is combined with a polyfunctional wood-based knob. This study aims to solve the problems mentioned above by considering the use of a material made of solid wood.

Structure of the Invention The structure of the present invention is such that in a lead electrode formed by applying a paste-like active substance to a lattice-like skeleton, a polyolefin-based synthetic valve sheet in which a polyfunctional hydrophilic polymer is attached and M-polymerized is used as an anode. The gist of the present invention is an anode plate for a lead-acid battery, which is characterized in that it is used as an inner layer material or a surface layer material of an anode plate.

Means for Solving the Problems An inner layer material as an electrolyte supply source structure of the anode plate or a surface adhesion improving structure of the active substance of the anode plate;
The use of a polyolefin-based synthetic valve made of fibrillated branched fibers, which has improved wettability through treatment with a multifunctional parent tree [this has an extremely excellent effect. They found that it was possible to obtain

By the way, in the present invention, the wettability-improved product of polyolefin-based synthetic valve seats such as polyethylene by treatment with polyfunctional parent wood monomers refers to the "poly 1 mefin-based wet process" for which the present applicant applied for a patent in May 1988. It is the same as "Nonwoven Fabric" (Japanese Patent Application No. 115488/1988).

Therefore, for more details about this synthetic valve seat −
This is as described in the specification of the above-mentioned application, and only a summary thereof will be explained here.

First, a synthetic valve using a polyolefin such as polyethylene as a raw material is manufactured by a known method, and an aqueous solution containing a polymerization catalyst and a polyfunctional hydrophilic monomer (7) is added to 100+tffi parts of the synthetic valve. So 2
It is deposited in a proportion of ~30 parts by weight, and heated and polymerized by steaming or the like.

At least 50% of the hydrophilic synthetic pulp obtained in this way was
0% or more, and suitably blend acid-resistant glass fibers, polyester fibers, acrylonitrile fibers, thin/saya composite fibers of polypropylene and polyethylene, etc., and use a wet papermaking method to produce fabrics with a basis weight of 50 to 150 g/ln' and a thickness of 0. 1
It is made into a nonwoven fabric sheet with a thickness of ~1 mm.

As a result, the resulting synthetic valve seat has fibrillated fibers, so unlike a simple fibrous material, it has extremely high liquid retention properties, and the hydrophobicity of the polyolefin is due to the polymerization of the polyfunctional parent wood monomer. Since it has been made hydrophilic through treatment, its liquid retention properties are further improved.

Examples of the polyfunctional hydrophilic monomer which is a wood-loving agent for this synthetic valve seat include polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, etc., and the average number of segments of this polyethylene oxide is 2 to 30. The one that can be suitably used is one that is.

In addition, as this hydrophilic agent, in addition to the multifunctional wood-loving monomer, acrylic acid, acrylamide, itaconic acid, vinylpyrrolidone, maleic acid, etc., which are well-known wood-loving monomers, are appropriately used in combination for copolymerization. Of course, it is okay to do so.

The greatest feature of the present invention is that the hydrophilized polyolefin synthetic valve sheet as described above is used as an inner layer material or surface layer material for an anode plate of a lead-acid battery.

FIG. 1 is a longitudinal sectional view of one embodiment of the anode plate of the present invention, showing a case where a polyethylene synthetic valve seat is used as the inner layer material.

As shown in this figure, the inner layer material (2) is closely attached to the lead lattice framework (1), and a paste-like active material (3) containing lead oxide or sulfuric acid is applied from both sides. The material (2) is sandwiched and held in place.

Since this inner layer material (2) is a polyethylene synthetic valve seat treated with wood as described above, it has excellent liquid retention properties for sulfuric acid solution, making it extremely effective as an electrolyte supply source structure. It will become. In addition, the fibrillated pulp structure and wood-filtering treatment not only improve liquid retention but also improve adhesion to paste, making it even more useful as an inner layer material.

FIG. 2 is a cross-sectional view of another embodiment of the anode plate of the present invention, in which a polyethylene synthetic valve seat is used as the surface layer material.

As shown in this figure, a paste-like active substance (3) similar to that described above is applied to a lead lattice structure (1), and a surface layer material (4) is adhered to the outside to further protect the surface. A membrane (5) is provided.

Since this surface layer material (4) is the aforementioned hydrophilic treated polyethylene synthetic valve seat, it has good wettability and does not have a negative effect on ion diffusivity or electrical resistance, and the elasticity of this sheet allows it to withstand expansion and contraction. This improves the adhesion with the paste and prevents the active substance from falling off or flowing out.

Example 1 To 100 parts by weight of polyethylene synthetic pulp, 12 parts by weight of an aqueous solution of polyethylene glycol diacrylate monomer having 15 ethylene glycol segments to which an appropriate amount of supersulfurized ammonium catalyst was added as a heptamer component was deposited. A hydrophilic synthetic pulp with 9.8% polymer adhesion was obtained by heating and polymerizing in a steamer at 100° C. for 1 hour.

Next, 75% by weight of this hydrophilic synthetic pulp and! iV
25 wt.
A sheet material used in the present invention was prepared by making paper to a thickness of 0.3 mm.

The size of the obtained sheet material is 50mm x 601II1
The lead electrode is laminated on the lead grid of No. 1, and the lead paste is applied from above, and then the grid is turned over and the lead paste is applied from the opposite side, and the sheet material is arranged in the center as the inner layer material. It was created.

In order to investigate the performance of this electrode, we investigated the discharge capacity when varying the discharge current and repeated 5 ampere discharges.1. The effective discharge cycles were measured and the results are shown in Tables 1 and 2.

In addition, for comparison with these, the same test as in Example 1 was conducted for the case where the sheet material used in the present invention was not used. The results were shown in

As is clear from these tables, the lead electrode of the present invention has
Compared to the comparative example, the reduction in discharge capacity due to high rate discharge was small, and the battery had excellent performance such as a long life with a large charge/discharge cycle.

Table 1 Table 2 Example 2 Lead paste was applied to both sides of the same lead grid used in Example 1, and a sheet material of -. A lead electrode of the present invention was created by stacking the layers to form a sandwich structure, and then layering a protective film on top of the layer to create a one-layer structure different from that of Example 1, using a sheet material as the surface layer material. did.

In order to investigate the performance of this electrode, the electrical resistance was measured117 according to JIS-C2313, and the impression during charging and discharging was also investigated, and the results are shown in Table 3.

For comparison, the same tests as in Example 2 were carried out on sheet materials that were the same as those used in the present invention but were not subjected to the parent wood treatment. The results are shown in the table.

As is clear from this table, the lead electrode of the present invention has lower electrical resistance than that of the comparative example, and has excellent performance with no bubbles or short circuits during charging and discharging. Ta.

C. Effects of Civilization The present invention is as described above, and when treated to make it hydrophilic and used as the inner layer material of a polyolefin synthetic valve sheath HL anode plate, this layer has an extremely excellent preservation ability, so it can withstand sulfuric acid solution. In addition, as an electrolyte supply source, it is possible to easily supply sulfuric acid even during high rate discharge, and to improve the discharge capacity. In addition, since it has good adhesion with the active substance, it exhibits drop-off prevention properties and has a good cycle life and condensation.
It becomes something that makes you feel better.

In addition, when a polyolefin-based synthetic valve sheet that has been treated with wood is used as the surface layer of the anode plate, it has excellent wettability and the valve structure. The elasticity of this synthetic pulp sheet prevents the anode active material from expanding or contracting. This has the effect of maintaining the adhesion of the peach and preventing the active substance from falling off or flowing out.

[Brief explanation of the drawing]

Figure $1 is a longitudinal cross-sectional view of one embodiment of the anode plate of the present invention, in which a polyethylene synthetic valve seat is used as the inner layer material. FIG. 2 is a cross-sectional view of another embodiment of the anode plate of the present invention, in which a polyethylene synthetic valve seat is used as the surface layer material. (1)... Lattice skeleton, (2)... Inner layer material, (3)
...Paste active substance. (4)...Surface material, (5)...Protective film 2nd
figure

Claims (1)

[Claims] 1. In a lead electrode formed by coating a paste-like active substance on a lattice-like skeleton, a polyolefin-based synthetic valve sheet on which a polyfunctional hydrophilic monomer is attached and polymerized is used as an anode inner layer material or an anode plate. An anode plate for a lead-acid battery, characterized in that it is used as a surface layer material.