JP4274873B2 - Lead-acid battery substrate and lead-acid battery using the same - Google Patents

Description

  The present invention relates to a lead-acid battery substrate and a lead-acid battery using the same.

  In recent years, the engine compartment of automobiles has increased in temperature due to the increase in equipment and the design that eliminates wasted space, etc., and coupled with being constantly overcharged, automotive lead-acid batteries are among the lead-acid batteries. Used in the most severe conditions. For this reason, deformation due to elongation called substrate corrosion of the positive electrode or gloss of the substrate is likely to occur, and since it reaches the end of its life, there is a strong demand for improvement. On the other hand, maintenance-free is also strongly demanded from the viewpoint of convenience, and the alloy composition of the substrate is Ca 0.06-0.10 mass%, Sn 1.0-2.0 mass%, Al 0.005-0. The lead-calcium alloy of 04 mass% and the balance Pb was used, but a sufficient effect was not obtained for improving the life of the lead-acid battery, that is, improving the corrosion resistance and suppressing the gloss.

  These conventional substrate alloys are improved and mechanical strength is maintained by a lead alloy in which 0.05% by mass or more of Ca, Sn, and Al is added to less than 0.02% by mass of Ba (Patent Document 1) And a lead alloy to which Ca 0.025 to 0.06% by mass, Sn 0.3 to 0.7% by mass, and Ag 0.015 to 0.045% by mass have a long life even at high temperatures (patent document) 2) is known.

  However, more essentially, it causes elongation deformation caused by the elongation stress generated by the corrosive material generated when using the lead storage battery, that is, gloss, impairs the electrical connection between the substrate and the active material, lowers the lead storage battery capacity, and Is to cause problems such as short-circuiting due to electrode plate deformation, and improvement in strength can reduce gloss, but since gloss is a joint phenomenon of both factors of corrosion and strength, its effect is effective unless the corrosion reaction can be sufficiently reduced. It is clear that is limited. In this respect, it cannot be said that both of the improved lead alloys are sufficient.

  On the other hand, the present inventors previously proposed a completely new lead alloy (Japanese Patent Application No. 2002-116593). This lead alloy is calcium 0.02 mass% or more and less than 0.05 mass%, tin 0.4 mass% or more and 2.5 mass% or less, aluminum 0.005 mass% or more and 0.04 mass% or less, barium 0.002 % By mass or more and 0.014% by mass or less, the balance being composed of lead and inevitable impurities, or further 0.005% by mass to 0.07% by mass of silver, 0.01% by mass or more and 0.10% by mass % Or less of bismuth and 0.001% by mass or more and 0.05% by mass or less of at least one element selected from the group consisting of thallium. According to this lead alloy, both the corrosion resistance and the mechanical strength can be improved and the essential problems can be solved, and a long-life lead-acid battery can be provided as compared with the above lead alloys.

JP 2000-504783 A (refer to page 6, line 1 to line 11) U.S. Pat. No. 5,298,350 (see column 4, line 38 to column 5, line 25)

  Improvements in corrosion resistance and mechanical strength due to the alloy composition of the above-mentioned lead alloy substrate are effective in extending the life of lead-acid batteries, but in recent years, automobiles require hybrid functions such as idling stop and start assist to improve fuel economy. In addition, improvement of discharge characteristics at a large current has been demanded. However, since the above alloys have extremely excellent corrosion resistance, it is difficult to bring the substrate surface into close contact more than before in the aging process in which the adhesion between the substrate and the active material paste is enhanced by oxidation of the substrate surface, which improves the high current discharge characteristics. I cannot respond to the request.

  The present invention is characterized in that calcium in the substrate alloy is less than 0.05 mass%, and the surface roughness of the substrate (Rz: 10-point average roughness defined in JIS B0601) is 15 μm or more. Is.

  The corrosion resistance of the alloy tends to be improved when the Ca content in the alloy is small, and is remarkably improved particularly at less than 0.05% by mass. On the other hand, it is difficult to improve the adhesion between the substrate and the active material, but by increasing the surface roughness (Rz) of the substrate to 15 μm or more, the adhesion can be improved and the discharge characteristics at a large current can be improved. it can.

  The present invention is considered to be achieved by the interaction between the surface roughness of the substrate and the alloy composition. When the surface roughness is increased, the adhesion is improved by mechanical bonding due to the anchor effect. However, the adhesiveness between the active material paste and the substrate is not sufficient by itself, and chemical bonding must be sufficient. That is, in the present invention, the chemical bond between the substrate surface and the active material acts more than the anchor effect. In general, a substrate filled with an active material paste has a high pH on the surface during the aging process in a high temperature and high humidity environment, and lead ions are generated. However, although the reason is not clear, when the roughness (Rz) of the substrate surface is greater than 15 μm, the valley of the cross-sectional curve of the surface of the substrate filled with the active material paste has a higher pH than the peak, Dissolution of the substrate surface is further promoted. This is considered to be because when the surface roughness (Rz) is 15 μm or more, the valley portion has a higher moisture content than the mountain portion. As a result, the dissolved lead ions can form an appropriate corrosion layer on the active material and the substrate surface, thereby improving adhesion and improving discharge characteristics at a large current.

  On the other hand, when the amount of calcium in the alloy is 0.05% by mass or more, this corrosive layer is porous, and the thickness increases remarkably due to repeated charge and discharge, causing cracks and increasing the electrical resistance between the substrate and the active material. On the other hand, if the calcium content is less than 0.05% by mass, the corrosion layer becomes dense, and deterioration due to repeated charge and discharge is almost eliminated. Therefore, when the surface roughness (Rz) of the substrate using an alloy having a calcium amount of 0.05% by mass or more is set to 15 μm or more, a porous corrosion layer develops and adhesion is not improved, but also at a large current. Discharge characteristics will deteriorate. On the other hand, it is considered that an alloy having a calcium content of less than 0.05% by mass forms a dense corrosion layer, exhibits good adhesion and low electrical resistance, and improves discharge characteristics at a large current.

  According to the present invention, large current discharge characteristics can be improved, and further effects such as contribution to expansion of applications can be achieved.

As shown in FIG. 1 by gravity casting with a book mold using 0.04% Ca-1.00% Sn-0.020Al-0.008% Ba- Pb (% is mass%, the same applies hereinafter) lead alloy. A lattice substrate in which a plurality of vertical lattices 1 and horizontal lattices 2 orthogonal to each other are surrounded by a frame lattice 3 was cast. 4 is an ear. Casting was performed at a rate of 15 sheets per minute. Then, a cork powder dispersed in water is used as a release material to be applied to the mold, and the surface roughness (Rz) of the lattice substrate is set to 10 μm by using the cork powder having different particle sizes.
m, 15 μm, 25 μm, and 45 μm. The lattice substrate was heat-treated at 100 ° C. for 1 hour and age hardened.

  The obtained lattice substrate was coated with an active material paste prepared by kneading lead powder with dilute sulfuric acid, then aged in an atmosphere of a temperature of 40 ° C. and a humidity of 95% for 24 hours, and dried. The obtained electrode plate was used as a positive electrode, and this was combined with a negative electrode manufactured by a conventionally known method and a polyethylene separator, housed in a battery case, covered, and diluted with sulfuric acid having a specific gravity of 1.200 as an electrolyte. A 6-cell monoblock lead-acid battery having a 5-hour rate capacity of 48 Ah was produced. This lead-acid battery is a liquid-type lead-acid battery provided with a large amount of electrolytic solution that is liberated.

  After this lead storage battery was left in an atmosphere of −15 ° C. for 16 hours, it was discharged at a current of 300 A until the storage battery voltage reached 6 V, and the voltage at 30 seconds at this time was measured. The results are shown in Table 1.

  Furthermore, the same test was conducted by changing the alloy composition of the lattice substrate and its surface roughness (Rz) as shown in Table 1. The results are shown in Table 1.

  As is apparent from Table 1, when the battery numbers are 1-1 to 1-4, the voltage at 30 seconds is as low as 9.72 V in the case of 1-1 where the surface roughness (Rz) of the substrate is 10 μm. However, in 1-2 to 1-4 where the surface roughness (Rz) is 15 μm or more, the voltage at 30 seconds is as high as 9.93 to 9.99 V, and the large current discharge characteristics are more excellent. I understand that. Further, in the storage battery numbers 2-1 and 2-2 using the lattice substrate with the calcium amount increased to 0.048%, the surface roughness (Rz) is 25 μm as compared with the case where the surface roughness (Rz) is 10 μm (2-1). In the case of (2-2), it can be seen that the voltage at the 30th second is high and has the same tendency.

  Further, the alloy composition ranges from 0.02 to less than 0.05% for Ca, 0.4 to 2.5% for Sn, 0.005 to 0.04% for Al, and 0.002 to 0.014% for Ba. When the surface roughness (Rz) was 15 μm or more, the voltage at the 30th second was high and there was almost no change. Further, even if one or more elements are added in the range of 0.005 to 0.07% Ag, 0.01 to 0.10% Bi, and 0.001 to 0.05% of Tl, almost no results are obtained. There was no change and good results were obtained. Further, even if inevitable impurities are contained in the lead alloy, the results are similarly good, and those in the alloy composition range are particularly excellent in corrosion resistance and mechanical strength, and are preferable.

  On the other hand, as shown by storage battery numbers 3-1 to 4-2, a storage battery using a lattice substrate with a calcium amount of 0.050% or 0.070% has a substrate surface roughness (Rz) of 15 μm or more. However, the voltage at the 30th second has no change or is low, and it can be seen that it is effective when a lead alloy containing less than 0.05% of calcium is used.

  Note that the lattice substrate can be obtained by a method such as continuous casting or rolling, and in order to further roughen the surface, there is a method such as spraying sandblast, and either method may be used.

  In addition, according to the present invention, a lead storage battery with improved large current discharge characteristics can be obtained, such as a high-voltage type lead storage battery such as a hybrid storage battery or a 36V storage battery for an automobile, or a UPS (uninterruptible power supply). ) For lead storage batteries, and its uses are diverse.

  In addition, even if it uses the lead alloy which remove | excluded Al from the lead alloy used in the said embodiment as a lead alloy, there exists the same effect, for example, the same result is obtained even if it uses each alloy of Table 2. It was confirmed. In addition, when casting an alloy excluding Al, it is preferable to cast in a non-oxidized state, for example, in a vacuum state or an inert gas state, thereby preventing Ca oxidation loss and easily controlling the Ca amount. .

Front view of a lattice substrate according to an embodiment of the present invention

Explanation of symbols

1 Vertical lattice 2 Horizontal lattice 3 Frame lattice

Claims (3)

Substrate is calcium 0.02 mass% or more and less than 0.05 mass%, tin 0.4 mass% or more 2.5 mass% or less, aluminum 0.005 mass% or more 0.04 mass%
Hereinafter, lead characterized in that barium is 0.002% by mass or more and 0.014% by mass or less, the balance is made of a lead alloy composed of lead and inevitable impurities, and the surface roughness (Rz) of the substrate is 15 μm or more. Storage battery substrate. The substrate is calcium 0.02 mass% or more and less than 0.05 mass%, tin 0.4 mass% or more and 2.5 mass% or less, barium 0.002 mass%
A lead-acid battery substrate , wherein the balance is 0.014% by mass or less, the balance is made of a lead alloy consisting of lead and inevitable impurities, and the surface roughness (Rz) of the substrate is 15 μm or more. Lead-acid battery, characterized in that using the substrate for one of lead-acid battery according to claim 1 or 2.

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