JPH05299094A - Composite grid for lead-acid battery - Google Patents

Abstract

PURPOSE:To increase the corrosion resistance of a grid and extend the service life thereof by covering the surface of a battery composite grid of such a structure as stacked via a rein sheet laid between the lead sheets of the predetermined thickness, with a coating material of acid resistant polymer blended with a conductivity adding agent. CONSTITUTION:The stacked structure of a gird is such that a resin sheet 38 of thickness between 0.3 and 1.2mm as a core material is stacked between two thin lead sheets 36 of thickness between 0.1 and 0.4mm. Olefin resin such as polyethylene and polypropylene having resistance against acid, reduction and oxidation, good adhesion to an active material, allowing service at high temperature and further having good expansion quality is suitable for the material of the sheet 38. Also, an adhesive capable of resisting the separation of both layers due to the repetition of discharging and charging is selected for stacking the layers. Epoxy resin blended with a conductivity adding agent such as Ketjen black and acid resistant polymer such as chlorofsulfonated polyethylene can be used as the coating material of a covering layer 40.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composite grid for a lead storage battery, and more particularly to a structure of a composite grid having high corrosion resistance and long service life.

[0002]

BACKGROUND ART Lead acid batteries have been conventionally known as secondary batteries and are widely used in power sources for automobiles, households, and industrial fields. In the background of the rapid progress of cordless devices due to the progress of the electronics field, it is required to reduce the weight of heavy lead-acid batteries.

Above all, there is a great demand for reducing the weight of a heavy grid made of a lead plate having a thickness of about 0.5 to 2.0 mm. That is, as a grid in such a lead storage battery, a lead grid of a cast product or an expanded grid or the like is used, but these are usually a plurality of grids as shown in FIG. The positive electrode plate 10 and the plurality of negative electrode plates 12 are alternately combined in the electrode plate main body portion (lattice-shaped portion) with the separator 14 interposed therebetween, thereby forming the electrode plate group 1
6, the ear portion 18 of each positive electrode plate 10 is connected to the positive electrode conductive portion 20, while the ear portion 22 of each negative electrode plate 12 is connected to the negative electrode conductive portion 24 for use. Is becoming Therefore, the weight of the electrode plate group 16 is
This is because it accounts for about 30% of the total weight of the storage battery.

In order to meet the demand for weight reduction and higher performance of the grid in such a lead storage battery, 0.1
Between two thin lead plates of ~ 0.4mm, 0.3 ~ 1.2
A lattice of a composite structure (hybrid structure) in which a resin sheet having a thickness of about mm is interposed and integrally laminated and bonded is considered.

However, in a lead storage battery, when an overcharged state continues for a long time, the oxidation reaction accelerates the oxidative corrosion of the lead plate. In addition to being thin, sulfuric acid gradually penetrates into the interior from the interface between the lead plate and the resin sheet, and corrosion progresses from both sides of the lead plate.
There is a problem that the lead plate is easily peeled off or broken. As a result, poor conduction is caused, or the active material falls off, which causes a problem that the useful life of the lattice is reduced. Further, because of such low corrosion resistance, such a hybrid structure lattice can be used as a negative electrode plate in which the oxidation reaction is relatively mild, but it is difficult to apply it to a positive electrode plate in which the oxidation reaction is intense. The effect of reducing the weight of the electrode plate group was halved.

Further, since the grid having the hybrid structure has the resin sheet interposed between the lead plates, it has a drawback that the conductivity as a whole is lowered, and it is necessary to increase the capacity of the grid by that amount. It was

[0007]

The present invention has been made in view of such circumstances, and the problem to be solved is to provide a grid for a lead storage battery having a composite structure (hybrid structure) of a lead plate and a resin sheet. In order to improve its corrosion resistance,
The purpose of this is to prevent the lead plate from peeling or breaking and to extend the service life of the grid. It is also to enhance the conductivity of such a lattice.

[0008]

In order to solve the above problems, in the present invention, in a storage battery composite grid having a laminated structure in which a resin sheet is interposed between lead plates having a predetermined thickness,
The surface was coated with a coating material made of an acid resistant polymer and a conductivity-imparting agent.

[0009]

[Operation / Effect] In short, in the present invention, the surface of the lead-acid battery composite grid, including the lead plate and the resin sheet, is coated with a coating material having acid resistance (sulfuric acid resistance) and conductivity. is there. Therefore, the coating material can effectively suppress both the corrosion from the outer surface of the lead plate and the corrosion from the interface between the lead plate and the resin sheet, and thus the life extension of the lattice is extremely effective. Can be achieved. And since it has such excellent corrosion resistance, the grid can be used for both the negative electrode plate and the positive electrode plate, and the electrode plate group,
As a result, the total weight of the lead acid battery can be significantly reduced. Further, in the lattice, since the corrosion resistance is enhanced by the coating material, the thickness of the lead plate can be made thinner, and the weight can be further reduced.

Since the coating material also has excellent conductivity, the charge / discharge reaction in the lattice is not hindered. Furthermore, since the resin sheet is interposed between the lead plates, the electrical conductivity of the lattice, which is reduced by forming a composite structure, is advantageously increased based on the excellent conductivity of the coating material. The capacity loss of the grating can be advantageously reduced.

[0011]

EXAMPLES In order to clarify the present invention more specifically, representative examples of the lead-acid battery composite grid according to the present invention will be described in detail with reference to the drawings.

First, FIG. 2 shows a grid 30 having a structure according to the present invention, which constitutes an electrode plate group (see FIG. 1) housed in a battery case of a lead storage battery. The lattice 30 has a substantially rectangular plate shape, and has an expanded portion 32 formed by expanding to form a lattice, and an upper portion 34 of the lattice. As shown in the side view on the left side of FIG. 2, the grid 30 has a laminated structure and is provided between two thin lead plates 36 having a thickness of 0.1 to 0.4 mm. As a core material, it has a structure in which resin sheets 38 having a thickness of 0.3 to 1.2 mm are laminated, and thereby the weight of the lattice 30 is significantly reduced.

The resin sheet 38 generally has acid resistance (sulfuric acid resistance), reduction resistance and oxidation resistance,
Good adhesion to the active material, high temperature use (-30 ℃ ~ +10
Characteristics such as being capable of about 0 ° C are required. Further, when the lattice 30 is formed by the expanding process as in the present embodiment, it is required that the expanding property is good and there is no deformation or shrinkage after the expanding.

Examples of the resin material satisfying such requirements include olefin resins, and various known polyolefins such as polyethylene, polypropylene and chlorosulfonated polyethylene, and modified products thereof are preferably used. You can Further, a modified resin such as a polyolefin in which a polar group such as a carboxylic acid anhydride group or a carboxyl group is introduced by addition of maleic anhydride or the like can also be used. Among them, polypropylene is preferable.

The lead plate 36 and the resin sheet 38 are laminated according to a conventional method to form an integrated laminated board. Normally, the lead plate 36 and the resin sheet 38 are bonded to each other,
The adhesive is applied to the lead plate 36 side. As this adhesive, it is necessary to select one that withstands peeling of the lead plate layer-core material layer due to repeated discharge and charge. Further, in the case where the laminated substrate is expanded and formed into a lattice shape as in the present embodiment, it is preferable that the laminated substrate has a flexible characteristic that follows the expansion.

For example, as disclosed in JP-A-2-256160, 2,4,6-trimercaptotriazine or 2-mercaptobenzothiazole dicyclohexylamine salt or both of them are added to a halogen-containing polymer or elastomer. It is possible to use an adhesive obtained by blending at least a cross-linking agent consisting of and a lead oxide-based cross-linking aid. Epoxy adhesives are also suitable, and for example, an adhesive in which soluble nylon is mixed as a curing agent in a bisphenol type epoxy resin can be used. Further, in order to increase the adhesive strength, the bonding surface of the lead plate 36 may be appropriately sanded or primer-treated.

The lattice 30 having such a laminated structure is covered with a coating material having acid resistance (sulfuric acid resistance) and conductivity from the lattice upper portion 34 to the expanded portion 32. Depending on the lead plate 36
And the coating layer 40 that integrally covers the resin sheet 38 is formed (see FIG. 3). That is, such a lattice 3
At 0, the coating layer 40 suppresses corrosion from the outer surface of the lead plate 36, and the lead plate 36 and the resin sheet 38
Sulfuric acid is prevented from entering the interface and corrosion from the interface is also suppressed, so that peeling and breakage of the lead plate 36 are effectively prevented, and thus the life of the lattice 30 is extended. It has been done. Further, the active material with which the expanded portion 32 of the lattice 30 is filled is applied onto the coating layer 40, but since the coating layer 40 has excellent conductivity, The charge / discharge reaction is not hindered.

By the way, the coating material for providing the coating layer 40 is made of a polymer having acid resistance (sulfuric acid resistance) and a conductivity-imparting agent. As the acid-resistant polymer therein, various conventionally known polymers can be used, and one having good adhesiveness to the lattice 30 is preferably selected. For example, epoxy resin, chlorosulfonated polyethylene, chlorinated polyethylene and the like can be mentioned. On the other hand, various known conductivity-imparting agents can be used, and one having high electric conductivity is preferably selected. Examples thereof include carbon such as Ketjen black, graphite, metal oxides such as PbO, and metal powder.

If the content of the conductivity-imparting agent in the coating material is too small, the conductivity cannot be obtained. On the other hand, if the content is too large, the mixing becomes non-uniform, and the conductivity-imparting agent is removed. Since there is a problem that occurs, the conductivity imparting agent is usually
The amount is 15 to 50 parts by weight based on 100 parts by weight of the polymer. However, a more specific blending amount will be appropriately determined according to the degree of conductivity of the conductivity-imparting agent used, and in the case of highly conductive Ketjen Black or the like, even if about 10 parts by weight, good conductivity can be obtained. However, PbO or the like needs to be mixed in an amount of about 20 parts by weight or more in order to obtain good conductivity. The volume resistivity of the coating material is preferably 10 Ω · cm or less.

In order to crosslink the acid-resistant polymer, the coating material may include a cross-linking agent such as tetramethyl-2-sulfide and tetramethyl-tetrasulfide, or a cross-linking agent such as PbO, litharge and Pb ₃ O _4. Auxiliary agents, and further crosslinking accelerators and the like will be appropriately blended.

When coating the grating 30 with such a coating material, the compound of the coating material is usually dissolved in a solvent such as toluene to be used as a liquid agent having a solid content of about 30%. Therefore, the dipping method or the spray method is preferably adopted. Further, the coating of the coating material can be continuously performed by the following method, whereby
The manufacturing cost can be advantageously reduced. That is, the lead plate 36 and the resin sheet 38 are continuously laminated to produce a long laminated substrate, which is continuously expanded,
The coating layer 4 is dipped in a coating material tank or sprayed with a coating material, and then continuously heat-cured.
0 is formed. The heat-curing treatment is performed under the condition that the crosslinking reaction of the coating material is sufficiently performed, and is usually at a temperature of 120 ° C to 170 ° C for 3 minutes to 10 minutes.
It is heated for about a minute. After that, the shape of the lattice 30 may be punched out from the long laminated substrate and the expanded processed portion 32 may be filled with the active material.

The grid 30 thus obtained has a covering layer 40.
Since it has excellent acid resistance and conductivity, it can be used as both a negative electrode plate and a positive electrode plate, and the weight of the lead acid battery as a whole can be advantageously reduced. Further, in the lattice 30, depending on the acid resistance of the coating layer 40, the lead plate 3
The thickness of 6 can be made thinner, and the weight reduction can be achieved more effectively. Furthermore, the coating layer 4
Depending on the conductivity of 0, the conductivity of the lattice 30, which is reduced by interposing the resin sheet 38, is advantageously increased, so that the capacity loss of the lattice 30 can be reduced.

Further, in Table 1 below, regarding the conventional two types of expanded lattices (lead lattice and hybrid lattice) and the expanded lattice of the present invention specifications having the above-mentioned structure, the lattice weight, the 5HR capacity, and the The results of measuring the service life are shown. In addition, all the measured values are shown as a ratio with the data of the conventional lead grid as 100%, and the evaluation is ⊚ for the case of 120% or more with respect to the data of the conventional lead grid, and 100 to 120% The case was marked with ◯, and the case of 80% or less was marked with x. As is clear from the results, the expanded lattice of the present invention has a lightweight structure based on a hybrid structure, and is provided with a coating layer excellent in acid resistance and conductivity, so that it has a long service life. long.

[0024]

[Table 1] (Note) * 1: Cycle at 40 ° C, SAE charge / discharge life test. * 2: The performance of the lead grid is the standard (100%).

Although the typical embodiments of the present invention have been described in detail above, it is needless to say that the present invention is not limited by the description of such embodiments. Further, in the present invention, in addition to the above-mentioned embodiments, unless departing from the gist of the present invention,
It should be understood that various changes, modifications, improvements, etc. can be made based on the knowledge of those skilled in the art.

For example, in the above-mentioned embodiment, the example in which the present invention is applied to the expanded grid has been described, but the present invention is not limited thereto and the present invention is applied to various kinds of lead-acid battery composite grids. Can be done.

[Brief description of drawings]

FIG. 1 is a perspective view showing a typical configuration of an electrode plate group used in a lead storage battery.

FIG. 2 is a left side view and a front view showing an embodiment of a grid according to the present invention.

FIG. 3 is an enlarged explanatory view showing an expanded portion of the lattice of FIG.

[Explanation of symbols]

 30 Lattice 32 Expanding part 34 Lattice upper part 36 Lead plate 38 Resin sheet 40 Coating layer

Claims (1)

[Claims] 1. A lattice having a laminated structure in which a resin sheet is interposed between lead plates of a predetermined thickness, the surface of which is a coating material prepared by mixing an acid resistant polymer with a conductivity-imparting agent. A composite grid for a lead storage battery, which is covered.