JPH03105855A - Manufacture of pole plate for lead-acid battery - Google Patents

Abstract

PURPOSE:To continuously process the cut face of an expanded metal grating so as to prevent elution of copper or copper alloy therefrom by forming a band portion prior to filling of paste, and then filling the band portion with paste, and cutting the band portion and then melting a thermoplastic resin to cover the cut face of the expanded metal grating with resin. CONSTITUTION:A rolled sheet of copper is developped to fabricate an expanded metal grating, and then an ear portion 5 and a leg portion 6 are both formed in that portion of the grating which is not expanded. The surface of the grating is plated with a thin film to fabricate a continuous grating body 1, and, ABS resin 3, which is one kind of thermoplastic resin, is applied to that portion 2 of the grating body 1 which is to be cut. After the continuous grating body 1 is filled with paste using a filling machine, the grating body 1 is cut into predetermined size and its resin-applied portion is pressed by a press and its copper grating portion which is exposed when cutting the expanded metal grating is completey covered with resin. Thus the cut face of copper or copper alloy is completely covered with thermoplastic resin so that elution of copper and self-discharge are avoided when the expanded metal grating is immersed in a dilute sulfuric acid.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a method for producing electrode plates for lead-acid batteries, and in particular, to continuously produce electrodes for lead-acid batteries by expanding thin plates made of copper or feed alloy. This paper concerns improvements in the method of manufacturing plates. Conventional technology and its challenges Lead-acid batteries are widely used as power sources for power, transportation, and stationary use, and are widely used for starting automobiles due to their low cost and excellent high-rate discharge. Currently, there are several demands on lead-acid batteries for starting motor vehicles, such as longer lifespan and improved high-temperature resistance due to their usage conditions, and one of these is a demand for higher output.

In general, methods for increasing the output of lead-acid batteries for starting automobiles, which have a 6-cell monoblock structure, include improving the inter-cell connection method to reduce the resistance at the inter-cell connections, and reducing the spacing between the electrode plates. Possible options include reducing the interelectrode resistance and increasing the concentration of dilute sulfuric acid as the electrolyte. However, these improvements have already reached their limits. Another method is to use a lattice body with excellent voltage characteristics, and by optimizing the shape, such as a case f body with diagonal lattice or a lattice body with radial lattice, One possibility is to use a material with good conductivity. Considering the cost, copper and copper alloys are the most suitable materials with good electrical conductivity. When copper or copper alloy is used for the grid, if its surface is exposed, that is, if the surface of the copper or copper alloy is in direct contact with dilute sulfuric acid, which is the electrolyte, copper will be removed when used for the positive electrode. is eluted and deposited on the negative electrode plate, and when used as a negative electrode, reactions other than the charging and discharging reactions of lead-acid batteries occur in the exposed part. That is, during charging, a hydrogen gas generation reaction occurs, resulting in insufficient charging of the negative electrode active material, and when left unused, the negative electrode active material forms a local battery with metal lead, increasing self-discharge. Therefore, it is necessary to use lead or lead alloy coatings on the surface of copper or copper alloy grids by electroplating or immersing them in molten metal. Grids made of copper and copper alloys are already used in large-scale batteries, such as lead-acid batteries for submarines, but the manufacturing process is extremely complex, and as is, they are used in large quantities to produce low-cost automobiles. This method cannot be applied to lead-acid batteries for commercial use. Therefore, as a manufacturing method that can be applied to lead-acid batteries for starting automobiles, a thin plate made of copper or copper alloy is expanded, ears and feet are formed on the unexpanded parts, and then the surface is covered with lead or! We have been studying a continuous method for producing electrode plates for lead-acid batteries by forming a coating layer of 9 alloy, filling it with paste, and cutting it into predetermined dimensions to obtain electrode plates. However, this manufacturing method has a problem in that new exposed surfaces of copper or copper alloy appear when the paste is filled and cut into predetermined dimensions.

Means for Solving the Problems The present invention first expands a thin plate made of copper or copper alloy, then forms ears or ears and feet on the unexpanded portions, and then molds the ears and feet on the surface. Forms a coating layer made of lead or lead alloy. Thereafter, a band-shaped portion made of acid-resistant thermoplastic resin, such as BS resin, is formed on the part to be cut in a subsequent process by means of applying such resin. Next, the paste is filled in the usual manner, and then the strip of mature plastic resin is cut at a predetermined position approximately in the center, and the thermoplastic resin is pressed in a press machine heated to a high temperature until it is completely melted. The thermoplastic resin portions at both ends are melted using the method described above, and the cut surfaces of the expanded lattice are coated with the resin. With this method, the cut surface of copper or feed alloy is completely covered with a mature plastic resin, and there is no copper elution or self-discharge even when immersed in fb sulfuric acid. EXAMPLES The present invention will be explained below based on examples. FIG. 1 is a diagram showing a state in which a band made of thermoplastic resin is formed near the cutting position of a continuous expanded grid.

First, the thickness is 0. An expanded lattice was made by rolling out a 2 mm rolled copper sheet. Ear portions 5 and foot portions 6 were formed on the portions that were not expanded. Then,
A continuous lattice body 1 was fabricated by plating a thin layer of a metal alloy on the lattice surface. Next, cut part 2 of the grid.
ABS @ Resin 3, which is a thermoplastic resin with acid resistance, was applied to the width of about 3 mm. 4 is the expansion part, 7
is the lower frame, and 8 is the upper frame. After this continuous grid was mechanically filled with paste, it was cut into a predetermined size.

After this, the area coated with resin was pressed using a press machine, and the copper lattice part exposed when cutting the expanded lattice was completely covered with resin. Figure 2 shows the completed electrode plate. Sealed lead-acid battery A, which uses the electrode plate produced by the method described above as the negative electrode plate, and Sealed lead-acid battery B, which has the same structure as battery A but uses a negative electrode plate whose cut surface is not coated with resin and the copper remains exposed. Furthermore, a sealed lead-acid battery C was prototyped by filling the same paste used in battery A into a conventional cast-alpha alloy grid as a negative electrode plate. For these three types of batteries, we conducted an overdischarge storage test in which copper elution is the most problematic issue. For the over discharge test, connect a 10W lamp to the test battery and leave it for one month, then 2.5
After charging at a constant voltage of V/cell, a 5hR capacity test was performed. After that, we conducted a life test as specified by SAE. The results are shown in Table 1. From the test results in Table 1, the 5hR capacity after constant voltage charging is:
Battery A using the negative electrode grid according to the present invention had almost no difference from Battery C using the conventional negative electrode grid or Battery B using the negative electrode grid with no coating on the cut surface, but after the capacity test @ In the SAE life test, battery A had a life expectancy of 4,500
Battery B, which used the expanded copper lattice as it was and had no coating on the cut surface, had a lifespan of only 500 °C.
'@ Pond B had a large amount of liquid loss, and the current at the end of charging during the life test was large, so it is thought that copper was eluted. Battery A, which uses the copper grid of the present invention, does not have this problem, and it can be seen that the effect of coating the cut surfaces of the copper grid with thermoplastic resin is remarkable. Note that similar results were obtained with batteries using copper alloy as an expanded grid instead of copper, so the method of coating the cut surface with thermoplastic resin according to the present invention is effective not only for copper but also for copper alloy. I found out something. Effects of the Invention As detailed above, according to the present invention, when a thin plate made of copper or copper alloy is expanded and a grid coated with lead or lead alloy is used as a negative electrode plate, the cut surface can be continuously and inexpensively processed. This makes it possible to prevent the elution of copper or copper alloys, which is extremely effective.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which a band made of thermoplastic resin is formed near the cutting position of a continuous expanded grid;
Figure 2 shows the completed electrode plate.

Claims (1)

[Claims] 1. Expanding a thin plate made of copper or copper alloy,
After forming ears or ears and feet on the part that has not been expanded, a coating layer made of lead or lead alloy is formed on the surface, and this is filled with paste and cut to a specified size to form the electrode. In a continuous method for manufacturing electrode plates for lead-acid batteries, a strip made of thermoplastic resin is formed in advance at the part to be cut to a predetermined size in the process before filling the paste, and then cut at a predetermined position after filling the paste. A method for manufacturing an electrode plate for a lead-acid battery, which comprises the steps of heat pressing to melt a thermoplastic resin and coating the cut surfaces of the expanded lattice with the resin.