JPS63174276A - Grid for use in lead battery - Google Patents

Abstract

PURPOSE:To obtain a lead plating layer with good adhesion to copper by forming a hot-dipped plating layer of lead alloy on the surface of a copper collector and forming an electroplating layer of lead thereon. CONSTITUTION:After a hot-dipped plating layer 2 of lead alloy is formed on the surface of an expanded copper collector 1 immersed in molten lead alloy, an electroplating layer 3 of pure lead is formed on foregoing layer in a lead plating solution as a grid. Using such a grid for a negative electrode, life tests of a lead battery composed of 4 plates of positive electrode and 5 plates of negative electrode are carried out. At a point of time elapsed 1800 cycles, the amount of gas generated during standing is almost same as the initial value indicating a good result in itself. By such arrangement of forming a hot-dipped plating layer of lead alloy and an electroplating layer of lead upon the copper or copper alloy collector, a lead coating layer with good adhesion to copper can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to improvements in negative electrode plates for improving the performance of lead-acid batteries, and in particular to improvements in which copper is used for the negative electrode grid.

Conventional technology and its problems Lead or a lead alloy has traditionally been used for the positive and negative electrode grids of lead batteries, regardless of whether they are a paste type or a clad type. This is due to the fact that its electrochemical and chemical properties, such as corrosion resistance and acid resistance in dilute sulfuric acid, are suitable for lead batteries, and its mechanical strength is almost sufficient, as well as being easy and inexpensive to manufacture. This is because it has excellent characteristics.

On the other hand, the drawbacks of lead alloy grids are that the density is quite high at about 11g/-, and the electrical resistance is about 20μΩ・], which is about 12~
It has a value as high as 13 times. Therefore, when it comes to large lead batteries, especially tall lead batteries, the resistance of the electrode plates increases significantly, and the further away from the electrode plate terminals the less it contributes to the charge/discharge reaction, resulting in a significant drop in charge/discharge performance. The disadvantage was that it decreased. In order to prevent this, it is necessary to use a large amount of lead alloy in the grid to reduce the voltage drop, but on the other hand, lead batteries are extremely heavy, and their volume increases, resulting in lower energy efficiency.
Wh /KljSWh /K) is extremely poor, making it impractical.

As mentioned above, copper as a lattice material has significantly lower electrical resistance than lead, and has a lower density of about 8.9 g/-, so when compared with the same weight, the electrical resistance is about 1/16th that of lead, and the same. When compared in terms of resistance, the weight is reduced to about 1/16. In addition, copper is a fairly stable metal in dilute sulfuric acid, and unless it is electrochemically oxidized by anodic polarization from the immersion potential, it will not be eluted into the electrolyte, so it cannot be used as a grid for the positive electrode plate. Although it cannot be used, it may be fully applicable as a negative electrode grid. For this reason, attempts have been made to use copper in the negative electrode grid instead of the lead alloy, but this has not yet been put to practical use because of the problem of increased self-discharge.

This is because the hydrogen overvoltage in dilute sulfuric acid is significantly lower than that in lead or lead alloys, so the amount of hydrogen gas generated from the negative electrode plate increases and the accompanying discharge reaction of the active material progresses.

Therefore, when using copper as a negative electrode grid,
The grid was coated with pure lead electroplating to prevent hydrogen overvoltage from decreasing in dilute sulfuric acid. However, the copper used for the grid, whether expanded or hammered, has many lead angle parts, so plating on such areas will increase the current density and cause dendrites to form. Easy to form and also? 1! This method has drawbacks such as the formation of a plating layer with poor adhesion to copper due to variations in flow distribution.

FIG. 2 is an enlarged cross-sectional view of a conventional copper grid, in which 1 is a copper expanded mesh collection, and 3 is a lead electroplated layer formed on the surface of the copper current collector 1.

Means for Solving the Problems The present invention eliminates the above-mentioned drawbacks when copper is used for the negative electrode grid of a lead-acid battery. Forms a layer)
Furthermore, an electroplated layer of lead is formed thereon. In other words, when hot-dip plating of lead alloy is performed on the surface of a copper current collector, the lead alloy is plated so that the acute corners of the copper lattice surface are rounded, so the current distribution during electroplating becomes uniform, and the copper and The lead plating layer has excellent adhesion.

Example The details of the present invention will be explained below with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view showing an example of a lead battery grid according to the present invention. In the figure, 1 is a copper expanded mesh. 2 is a lead alloy hot dip plating layer formed on the surface of the copper current collector 1, and 3 is a lead electroplating layer further formed thereon.

The lattice body according to the present invention is obtained by dipping an expanded copper current collector into a molten lead alloy to form a hot-dip plating layer of a lead alloy on the copper surface, and then electroplating pure lead in a lead plating solution. It is something. An example of the composition of a plating bath and plating conditions in hot-dip plating is shown below.

Hot-dip plating bath composition: Pb-0.1%) Hot-dip plating conditions: Temperature: 350-450°C Immersion time: 3-5 seconds Also, an example of the plating bath composition and plating conditions for lead electroplating is as follows. It is.

Plating bath composition: Pb<BFa )2 205 (+1/1
) HBF4 60 (') H2SO440 (/F) Gelatin 0.2 (!) Re-plating conditions: Temperature: 20-35°C Current: 60 mΔ/d Time: 30 minutes Using the lattice body according to the present invention as the negative electrode, 4 positive electrode plates and 4 negative electrode plates 5
A lead-acid battery with a capacity of approximately 170 Ah (5 hR) was manufactured and subjected to a life test. The test conditions were a charge-discharge cycle test of ambient humidity [30° C., discharge of 43A for 3 hours, charge of 31A for 5 hours. For comparison, a battery using a conventional copper grid with only a lead electroplated surface as the negative electrode was also tested. Figure 3 shows the change in the amount of hydrogen gas generated when the battery was left unused during the life test. In battery B using a conventional copper lattice body, the amount of hydrogen gas generated when left standing increases from around 1400.

This is considered to be because the adhesion between the copper and lead plating layer was poor and the plating layer peeled off, exposing the copper.

On the other hand, if 1 = battery A using the grid according to the present invention, then 18
After 00 or more, the amount of gas generated when left is almost unchanged from the initial value, showing a good transition.

Effects of the Invention As described above, the present invention provides a lead coating with excellent adhesion to copper by forming a lead alloy hot-dip plating layer and a lead electroplating layer on a current collector made of copper or a copper alloy. It forms layers, and its collective value is extremely great.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view showing an example of a lead battery grid according to the present invention;
Figure 2 is an enlarged cross-sectional view of a conventional example of a copper lattice body, and Figure 3 is a diagram comparing the transition in the amount of hydrogen gas generated when a lead battery using the lattice body of the present invention is left unused during a life test with a conventional battery. It is. 1... Copper current collector, 2... Hot dip plating layer, 3...
・Engraving of the lead electroplated layer (no changes to the content)
1. Indication of the case 1988 Patent Application No. 003856 2. Name of the invention Grid for lead batteries 3. Person making the amendment Relationship to the incident Patent applicant 〒601

Claims (1)

[Claims] 1. A grid for a lead battery, characterized in that a hot-dip plating layer made of a lead alloy is formed on the surface of a current collector made of copper or a copper alloy, and an electroplated layer of lead is further formed.