JP5236228B2 - Lead alloy for lead-acid battery and lead-acid battery using the same - Google Patents

Description

  The present invention relates to a lead alloy for a lead storage battery and a lead storage battery.

  Conventionally, lead parts such as straps of lead-acid batteries, inter-cell connections, and pole poles contain 3.5 to 6.0% Sb in pure lead which is inherently very soft and unsuitable for lead-acid battery lead parts. Pb—Sb alloys or Pb—Sn alloys containing 1.0 to 5.0% Sn are used. Pb—Sb alloys are very effective for improving the mechanical strength, but have the disadvantage that the amount of liquid reduction during charging is large in order to reduce the hydrogen overvoltage. On the other hand, the Pb—Sn alloy containing no Sb is a Pb—Sb alloy containing 3.5 to 6.0% Sb in the pure lead, or 1.0 to 5.0% Sn. Since it is higher than the contained Pb—Sn alloy, the amount of liquid reduction during charging is small, but the mechanical strength and corrosion resistance are inferior.

  As a method for solving these problems, a technique in which an appropriate amount of As or Ag is contained in a Pb—Sn alloy has been proposed.

  In Patent Document 1, at least one of the positive electrode lattice and the negative electrode lattice is made of a lead alloy not containing Sb, and the As content of the lead component such as the strap / cell connection portion / pole column is 0.02 to 0.5. %, Sn content of 1.0 to 5.0%, Ag content of 0.02 to 0.3%, and the balance being Pb, Pb-Sn system is proposed by adding these trace elements. The mechanical strength and corrosion resistance issues associated with alloys are improved.

  Included in lead-battery Pb-Sn-As alloys used in lead parts such as straps, inter-cell connection parts, and poles of lead-acid batteries due to the recent increase in consideration of the work environment of factories that manufacture lead-acid batteries and their surroundings It has been demanded to reduce the concentration of As.

  Since the As content contained in the Pb-Sn-As alloy is about 0.5%, the absolute value of the As content is very small when viewed from a lead storage battery (product), and its impact on the environment is negligible. It is believed that.

  However, As and its inorganic compounds are designated as “Specified Class I Designated Chemical Substances”, and if the As content in the Pb—Sn—As alloy can be reduced, the lead storage battery has a lower environmental impact. It is thought that it becomes.

However, as in Patent Document 1, if the As content is 0.15%, the Sn content is 3.0%, and the Ag content is 0.02%, both mechanical strength and corrosion resistance can be achieved. When the As content is less than 0.1%, the problem is that the mechanical strength and corrosion resistance of the lead alloy are reduced even when these trace elements are added.
Japanese Patent Laid-Open No. 01-189860

The present invention is, from the growing concern for the working environment and around the plant for manufacturing the lead-acid battery, a Pb-S n alloy having a reduced concentration of As between strap cell connecting portion, the terminal post and the like of the lead storage battery lead The present invention provides a lead alloy for a lead storage battery that ensures mechanical strength and corrosion resistance even when used in a component, and a lead storage battery using the lead alloy.

The invention according to claim 1 of the present invention is a lead storage battery strap, an inter-cell connector or a lead alloy for a pole pole, having a chemical composition of mass%, Sn of 1.0 to 5.0%, Bi Represents a lead alloy composed of 0.001 to 0.02%, As is 0.095% or less (including 0), and the balance is Pb .

The invention according to claim 2 of the present invention is characterized by further containing 0.001 to 0.02% of Ag. The lead storage battery excellent in durability can be obtained by using the lead alloy of Claim 1 or 2 for a strap, a connection body between cells, or a pole pole .

According to the configuration of the present invention described above, it is sufficient to actually use the Pb—Sn-based alloy in spite of reducing the As content which has been added to increase mechanical strength and corrosion resistance. It is possible to ensure high mechanical strength, corrosion resistance, and productivity (castability). Therefore, equivalent while significantly reduces impact on the As environmental, Pb-Sn-As alloy containing conventional about 0.2 wt% to 0.5 wt% As by reducing the As content The above mechanical strength and corrosion resistance can be obtained. Furthermore, by reducing the amount of addition of elements other than Pb and Sn to the minimum necessary, it is possible to obtain a lead storage battery that has almost no adverse effects on cost and battery characteristics.

The lead storage battery of the present invention has a chemical composition of mass%, Sn of 1.0 to 5.0%, Bi of 0.001 to 0.02%, As of 0.095% or less (including 0), the balance A lead alloy made of Pb is used for the strap, the inter-cell connector or the pole column .

Lead-acid battery of the present invention for the purpose of reducing the influence on As environmental, As content is 0.095 mass% or less of Pb-Sn- Bi alloys, also it is properly P b-Sn -Bi-Ag alloy Is used.

Lead-acid battery for a lead alloy of the present invention is the conventional Pb-S n alloy in order to maintain the added mechanical strength equal to or higher than the level that was obtained by the As, the Sn 1.0 to 5. While containing 0 mass%, Bi is contained 0.001-0.02 mass%. On the other hand, even if Bi is contained in an amount exceeding 0.02% by mass, a further improvement in corrosion resistance and mechanical strength cannot be expected, and a reduction in self-discharge characteristics and liquid reduction characteristics is also manifested.

In the form status of the present invention, the Ag content in addition to Sn and Bi in the Pb-Sn -Bi alloy 0. It is to be 02% by mass or less . By containing Ag, crystal growth of the alloy is inhibited, and mechanical strength and corrosion resistance increase. However, when the Ag content is more than 0.02% by mass in order to suppress the crystal growth of the lead alloy as a nucleating agent, the self-discharge characteristics and the liquid reduction characteristics are significantly deteriorated.

  Hereinafter, the effects of the present invention will be described with reference to examples.

In this example, as shown in Table 1, the As content was 0 to 0.15 mass %, the Sn content was 1.0 to 5.0 mass %, the Bi content was 0 to 0.02 mass %, and the Ag content was Lead components for lead-acid batteries were cast with a lead alloy having an amount of 0 to 0.02 mass % and the balance being Pb, and mechanical strength, corrosion resistance, and productivity were evaluated.

  About the lead alloys shown in Table 1, their mechanical strength was evaluated by a micro Vickers hardness test in which the load at the time of measurement was 10 gf in the Vickers hardness measurement specified in JIS Z2244 “Vickers hardness-test method”. did.

  Further, the corrosion resistance of the lead alloys shown in Table 1 was evaluated by the following method. For each lead alloy, a plate-shaped test piece having a width of 80 mm, a height of 80 mm, and a thickness of 1 mm is cast, and a working electrode, a pure lead plate having a width of 80 mm, a height of 80 mm, and a thickness of 1 mm is used as a counter electrode, and the working electrode is 1 mm. Bagged with a microporous separator. After that, the model cell was manufactured by sandwiching the working electrode with the counter electrode.

  Into this model cell, dilute sulfuric acid with a density of 1.30 g / cm3 (converted at 25 ° C) was injected, and the current was passed for 2 months at an apparent density of 0.5 A / cm2 between the working electrode and the counter electrode in a 75 ° C air tank. Thus, the weight loss of the working electrode was evaluated. During the experiment, when the dilute sulfuric acid liquid level in the model cell decreased due to gas generation or moisture evaporation, ion exchange water was appropriately supplemented.

  After two months of continuous energization, the working electrode is washed with water, the corrosive material on the working electrode surface is removed with a mannitol solution, washed again with water, dried, and then the mass of the working electrode with the corroded material removed (W1) Weighed. The percentage of the weight (W0) of the difference (W0-W1) between the mass (W0) of the working electrode measured in advance before the experiment and the mass (W1) of the working electrode after the experiment is calculated as the corrosion weight loss. The corrosion resistance was evaluated by The smaller the corrosion weight loss of the lead alloy, the better the corrosion resistance.

  Furthermore, a grid for a lead storage battery was cast using each lead alloy shown in Table 1. The castability of each alloy was evaluated based on the occurrence rate of casting defects such as broken bones in the casting lattice and defective defects. In addition, the bone defect was implemented by visually confirming the lattice body in which the frame bone and the middle bone of the lattice became discontinuous. Further, when the lattice after visual confirmation was folded into a V-shape, the lattice body cut at the bent portion and the lattice body where cracks of a level that can be visually confirmed occurred at the bent portion were regarded as burned.

Table 2 shows the mechanical strength (Vickers hardness), corrosion resistance (corrosion weight loss) and castability (casting failure rate) of various lead alloys shown in Table 1.

Lead alloys 19 to 22 are lead alloys according to comparative examples having an As content of 0.15% by mass . The lead alloys 19 and 21 containing Sn in addition to 0.15% by mass of As and containing no Bi and the lead alloys 20 and 22 containing Bi are not significantly different from each other in Vickers hardness, corrosion weight loss, and casting defect rate. . Moreover, these lead alloys have a track record in the market as lead alloys for lead-acid batteries, and are practical as lead alloys for lead-acid batteries except that they have a high As content.

In addition, it is in the tendency for the Vickers hardness to improve the lead alloys 20 and 22 which made As content 0.15 mass % and contained Sn and Bi compared with the lead alloys 19 and 21 which contained only Sn.

On the other hand, with regard to lead alloys 1 to 18 having an As content of 0, 0.01, 0.095% by mass , the presence or absence of Bi is particularly significant in the Vickers hardness, corrosion weight loss, and defective rate during casting. It has an influence.

In the lead alloys 1, 6, 7, 12, 13, and 18 not containing Bi, the Vickers hardness is lower than the lead alloys 19 to 22 having the As content of 0.15% by mass regardless of the Sn content. However, corrosion weight loss and the defective rate during casting are increasing. When the As content is reduced to 0.095 mass % or less, simply increasing the Sn content has practical mechanical strength and corrosion resistance compared to conventional lead alloys 19 to 22 for lead acid batteries. It is not suitable as a lead alloy for lead-acid batteries.

On the other hand, even when the As content is reduced to 0.095% by mass or less, lead alloys containing Sn in an amount of 1.0 to 5.0% by mass and Bi in an amount of 0.001 to 0.02% by mass 2,4 , 8, 10, 14, and 16 have the same Vickers hardness as a lead alloy with an As content of 0.15% by mass in the conventional example that has a proven track record in the market. A reduction effect was observed.

Furthermore, in the lead alloy in which the As content is 0.095% by mass or less, Sn is 1.0 to 5.0% by mass , and Bi is 0.001 to 0.02% by mass , Ag is 0.001%. Lead alloy 3,5,9,11,15,17 contained at ~ 0.02% by mass tends to have a Vickers hardness higher than that of lead alloys 2, 4, 8, 10, 14, 16 containing no Ag It can be seen that the weight loss of corrosion tends to decrease, and that a predetermined amount of Ag is more preferable as a lead alloy for a lead storage battery.

Further, the Bi content should be 0.001 to 0.02 mass %. When the content is less than 0.001% by mass, the improvement of mechanical strength and corrosion resistance due to the Bi content and the effect of reducing the casting defect rate are not recognized. Further, even if the Bi content exceeds 0.02% by mass , there is no effect of improving the mechanical strength and corrosion resistance, and the self-discharge characteristics and the liquid reduction characteristics are also lowered. Therefore, the Bi content is 0.02%. Should be less than mass %.

Also, the Ag content, preferably in the 0.001 to 0.02 wt%. When Ag content is less than 0.001 mass%, the improvement effect of mechanical strength and corrosion resistance cannot be expected. On the other hand, when the Ag content is increased from 0.02% by mass, there is no further effect of improving the mechanical strength and corrosion resistance, but rather there is a concern about an increase in cost due to an increase in Ag.

  According to the configuration of the present invention, it is possible to reduce the As content in a lead alloy for a lead storage battery that does not contain Sb, and to provide a lead alloy that uses an environment-friendly lead alloy and the lead alloy. It becomes.

  According to the configuration of the present invention, the alloy is obtained by making these various characteristics more preferable for the lead storage battery without deteriorating the mechanical strength, corrosion resistance and productivity required for the lead storage battery substantially free of Sb. As the content of As can be reduced, a lead-acid battery that is more favorable to the environment can be obtained, which is extremely useful industrially.

Claims (3)

Lead alloy for lead-acid battery straps, inter-cell connectors or pole poles,
Chemical composition is mass%,
Sn is 1.0 to 5.0%,
Bi is 0.001 to 0.02%,
As is 0.095% or less (including 0),
Lead alloy with the balance being Pb. Furthermore, 0.001-0.02% of Ag is contained, The lead alloy of Claim 1 characterized by the above-mentioned. The lead acid battery which has a strap using the lead alloy of Claim 1 or 2, a connection body between cells, or a pole column.