JP2005044760A - Manufacturing method of lead-acid storage battery positive electrode plate lattice - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Pb-Ca-Sn-Ba group alloy electrode plate lattice suitable for a lead-acid storage battery for an automobile or various kinds of lead-acid storage batteries for a backup use, excellent in mechanical strength and corrosion resistance. <P>SOLUTION: On the manufacturing method of the lead-acid storage battery electrode plate lattice, a rolling process with a total draft ratio of 50 to 97%, an expanding process, and an age-hardening process adding heat for 0.5 hours or longer at 80 to 160°C are applied in this order to a lead alloy material containing Ca by not less than 0.02 mass% and less than 0.05 mass%, Ba by not less than 0.002 mass% and not more than 0.014 mass%, Sn by not less than 0.4 mass% and not more than 2.5 mass%, with the rest part concsisting of Pb and inevitable impurities. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an electrode plate grid (hereinafter referred to as an expanded plate grid) that is suitable for an automotive lead storage battery or various backup lead storage batteries.

  A lead storage battery is configured by alternately arranging positive and negative electrode grids filled with an active material in an electrolyte. The plate grid plays the role of holding the conductive mechanism and active material during charge and discharge, and cast products have been used in the past, but in recent years, it has been expanded by the expansion process for the purpose of reducing the weight and improving the performance of the electrodes. Thin plate grids are being put into practical use.

  Since the expanded electrode plate lattice is manufactured by a process of casting → rolling → expanding, the lead alloy constituting the electrode plate lattice is required to have castability, rolling workability, and expandability. Requires mechanical strength that does not deform when filled with an active material or during handling.

  Conventionally, lead alloy containing 0.06 to 0.10 mass% of Ca, 1.0 to 2.0 mass% of Sn and 0.005 to 0.04 mass% of Al is used for the expanded electrode plate lattice. However, this lead alloy electrode grid has not been sufficiently compatible with lead-acid batteries used under severe conditions such as for automobiles in terms of mechanical strength, growth resistance and corrosion resistance.

  As an electrode plate lattice with improved mechanical strength and corrosion resistance, for example, Patent Document 1 discloses that Ca is 0.05 to 0.12 mass%, Sn is 3 mass% or less, and Al is 0.002 to 0.04 mass. An electrode plate lattice made of a lead alloy containing 0.02% by mass of Ba and Ba and having a high mechanical strength stably maintained by the specific structure of Ca and Ba is disclosed.

  Furthermore, the present applicant has improved Ca by 0.02 mass% or more and less than 0.05 mass%, Ba by 0.002 mass% or more and 0.014 mass% or less, and Sn by 0.4 mass% or more. Lead alloys containing 5% by mass or less, the balance being Pb and inevitable impurities, and these alloys are further added to Ag 0.005% by mass to 0.07% by mass, Bi 0.01% by mass to 0.10% by mass, Tl0.001 The lead alloy which added at least 1 sort (s) of the mass% or more and 0.05 mass% or less was proposed.

International Publication No. 97/30183 Pamphlet

Since the expanded electrode plate lattice is thin, the influence of corrosion on the life is large, and there is a problem that growth is likely to occur in the positive electrode lattice.

  The growth is elongation deformation (creep) caused by corrosive substances generated when the battery is used, and the growth is more likely as the strength of the electrode plate lattice is lower. When the gloss occurs, the electrical connection between the electrode plate lattice and the active material deteriorates and the battery capacity decreases, and the electrode plate may be deformed to cause a serious accident such as a short circuit. For this reason, the expanded electrode plate lattice is strongly required to improve mechanical strength and corrosion resistance.

  On the other hand, lead-acid batteries for automobiles are placed in the engine room where the temperature rises rapidly due to the increase in equipment and the elimination of extra space, and they are always overcharged. For lead-acid batteries for hybrid vehicles that can cope with environmental problems and fuel economy, a high voltage from 12V to 36V is planned to improve energy density, so that large currents can be charged and discharged at high temperatures. It has been studied to further reduce the thickness of the plate to increase the surface area. In addition, maintenance-free is also required for convenience.

  Under such circumstances, the expanded electrode plate grid for lead-acid batteries for automobiles has been required to further improve mechanical strength and corrosion resistance. However, these problems are related to backup lead-acid batteries for IT and energy storage. This is common to lead-acid batteries.

  However, the electrode plate lattice made of Pb—Ca—Ba—Sn—Al-based lead alloy shown in Patent Document 1 is good as a cast electrode plate lattice obtained by casting, but this is used as an expanded electrode plate lattice. In such a case, the above problem has not been sufficiently solved, and further improvement is desired.

  An object of the present invention is to produce an expanded electrode plate lattice excellent in mechanical strength and corrosion resistance that can be satisfactorily applied to lead-acid batteries for automobiles and the like.

  The invention according to claim 1 is a Pb—Ca—Ba—Sn based lead alloy or a lead alloy material containing an appropriate amount of at least one of Ag, Bi, and Tl in the lead alloy. % Rolling processing, expanding processing, and age hardening treatment in which heating is performed at 80 to 160 ° C. for 0.5 hours or more in this order.

  The invention according to claim 2 is such that Ca is 0.02 mass% or more and less than 0.05 mass%, Ba is 0.002 mass% or more and 0.014 mass% or less, and Sn is 0.4 mass% or more and 2.5 mass% or less. Including the following, the lead alloy material consisting of Pb and inevitable impurities is subjected to rolling processing with a total rolling reduction of 50 to 97%, expansion processing, and age hardening treatment in which heating is performed at 80 to 160 ° C. for 0.5 hours or more in this order. A method for manufacturing a lead-acid battery plate grid characterized by the following.

  According to a third aspect of the present invention, Ca is 0.02 mass% or more and less than 0.05 mass%, Ba is 0.002 mass% or more and 0.014 mass% or less, and Sn is 0.4 mass% or more and 2.5 mass% or less. In addition, it contains at least one of Ag 0.005 mass% to 0.07 mass%, Bi 0.01 mass% to 0.10 mass%, and Tl 0.001 mass% to 0.05 mass%. In addition, the lead alloy material consisting of Pb and inevitable impurities in the balance is subjected to rolling processing with a total rolling reduction of 50 to 97%, expanding processing, and age hardening treatment in which heating is performed at a temperature of 80 to 160 ° C. for 0.5 hours or more in this order. A method for manufacturing a lead-acid battery plate grid characterized by the following.

  As described above, according to the present invention, a thin-walled expanded electrode plate grid excellent in filling and holding properties of active material, growth resistance, corrosion resistance, etc. is obtained, and a lead-acid battery using this electrode plate grid is , Light weight, high voltage, high current charging / discharging at high temperature, etc., so it is enough for lead-acid batteries for automobiles (especially hybrid vehicles), UPS (uninterruptible power supply), IT industry etc. Applicable. Therefore, there is an industrially significant effect.

  According to the first aspect of the present invention, a lead alloy material containing an appropriate amount of Ca, Ba, Sn, or a lead alloy material (such as an ingot) containing an appropriate amount of at least one of Ag, Bi, and Tl in the lead alloy is rolled or expanded. , A lead-acid battery plate grid manufacturing method in which the age hardening treatment is performed in this order, and the alloy element enhances the manufacturing processability of processing a lead alloy material into a plate grid and is required for the electrode grid Strength, corrosion resistance, electrical conductivity, fillability of active material, retention, quality, etc. are enhanced, thereby improving the battery life.

  In the first aspect of the present invention, the reason why the total rolling reduction in the rolling process of the lead alloy material is defined as 50 to 97% is that the mechanical strength of the lead alloy strip is not limited even if the total rolling reduction is less than 50% or more than 97%. As a result, the flatness is lowered, and as a result, the lattice is deformed. If the total rolling reduction is 50 to 97%, the strip has an appropriate mechanical strength, the expanded material has a flat shape, and the lattice is formed in a uniform shape. Thereby, a short circuit accident due to deformation of the electrode plate grid is prevented, and the active material is satisfactorily filled in the electrode plate grid.

  In the present invention, the reason why the expanded material is subjected to age hardening treatment is that the mechanical strength is increased by age hardening treatment, and the electrode plate lattice is deformed at the time of filling or handling the active material, causing a short circuit accident or holding the active material. This is to prevent the performance from deteriorating. The reason for prescribing the age-hardening treatment condition to 80 to 160 ° C. is that sufficient mechanical strength necessary for preventing deformation cannot be obtained even when the temperature is less than 80 ° C. or exceeds 160 ° C.

  In the present invention, the reason for setting the aging treatment time to 0.5 hours or more is that when the aging treatment time is less than 0.5 hours, the mechanical strength varies greatly and the stability is lacking. The upper limit of the aging treatment time is preferably about 5 hours from the viewpoint of productivity.

A second aspect of the present invention is a method for manufacturing a lead grid for a lead storage battery in which the composition of the Pb-Ca-Ba-Sn alloy of the first aspect of the invention is defined.
Ca contributes to improvement of mechanical strength.
If the Ca content is less than 0.02% by mass, the effect is not sufficiently obtained, and if it is 0.05% by mass or more, the corrosion resistance is lowered. For this reason, the content of Ca is preferably 0.02% by mass or more and less than 0.05% by mass.
The more desirable content of Ca is 0.03 to 0.045% by mass.

Ba contributes to improvement of mechanical strength.
If the content of Ba is less than 0.002% by mass, the effect cannot be sufficiently obtained, and if it exceeds 0.014% by mass, the corrosion resistance decreases. Therefore, 0.002 to 0.014 mass% is desirable.

  The coexistence of Ca and Ba improves the corrosion resistance, and the interface between the electrode plate lattice and the active material is densified, so that the conductivity between the electrode plate lattice and the active material through the corroded layer is stable for a long time. A new effect of being maintained is developed and the battery life is further improved.

  Sn improves the molten metal flow and improves the quality of the ingot, and improves the mechanical strength of the electrode plate lattice. Furthermore, Sn elutes at the lattice interface during charge and discharge and is doped into the corrosion layer, causing a semiconductor effect in the corrosion layer, increasing the conductivity of the electrode plate lattice, and improving the battery life. If the Sn content is less than 0.4% by mass, the effect cannot be sufficiently obtained. If the Sn content exceeds 2.5% by mass, the crystal grains become coarse and intergranular corrosion proceeds more than apparent corrosion. Accordingly, the Sn content is preferably 0.4 to 2.5 mass%. A more desirable content of Sn is 0.6 to 2.5% by mass.

  According to a third aspect of the present invention, an appropriate amount of at least one of Ag, Bi, and Tl is contained in the lead alloy according to the second aspect. Ag, Bi, and Tl all have the effect of remarkably improving mechanical strength, particularly creep resistance (growth resistance) at high temperatures.

If the content of Ag is less than 0.005% by mass, the effect cannot be sufficiently obtained, and if it exceeds 0.07% by mass, cracks are likely to occur in the ingot during casting.
Therefore, the content of Ag is preferably 0.005 to 0.07% by mass.
A more desirable content of Ag is 0.01 to 0.05% by mass.

If the Bi content is less than 0.01% by mass, the effect cannot be sufficiently obtained. If the Bi content exceeds 0.10% by mass, the corrosion resistance decreases. Accordingly, the Bi content is preferably 0.01 to 0.10% by mass.
The more desirable content of Bi is 0.03 to 0.05% by mass.

If the content of Tl is less than 0.001% by mass, the effect is not sufficiently obtained, and if it exceeds 0.05% by mass, the corrosion resistance is lowered. Therefore, the content of Tl is preferably 0.001 to 0.05% by mass.
A more desirable content of Tl is 0.005 to 0.05% by mass.
Bi and Tl are cheaper and more economical than Ag.

  In the inventions according to claims 2 and 3, the reason for prescribing the total reduction ratio of the lead alloy material to 50 to 97% and the age hardening treatment condition applied to the expanded material are prescribed to 80 to 160 ° C. for 0.5 hour or more. The reason is the same as the case of the first aspect of the invention (see paragraphs 0014 to 0016).

Hereinafter, the present invention will be described in detail with reference to examples.
(Example 1)
The lead alloy having the composition defined in the inventions according to claims 2 and 3 shown in Table 1 is melt-cast by an ordinary method to form an ingot, and the ingot is rolled at a total rolling reduction of 75% to a thickness of 0.9 mm. It was made into a strip. Next, the strip was expanded, and this was cut into an electrode plate lattice having a predetermined size.

  The tensile strength of the raw strip was examined. Further, the flatness and the lattice shape of the electrode plate lattice were visually observed to determine whether they were good (◯) or defective (×). Further, the tensile strength and creep resistance characteristics after age-hardening treatment at 140 ° C. for 1 hour were examined for the strips, and the characteristics after age-hardening treatment of the electrode plate lattice were estimated.

  In the tensile test, a No. 13 B test piece was cut out from the strip and examined in accordance with ISO6892. For the creep resistance, a test piece with a width of 15 mm and a length of 150 mm was cut out from the strip and tested under the conditions of a distance between gauge points of 80 mm, a load of 16.4 MPa, and a temperature of 100 ° C. did.

(Comparative Example 1)
For the conventional Pb—Ca—Sn—Al-based lead alloy, strips and electrode plate lattices were produced under the same conditions as in Example 1, and the same investigation as in Example 1 was performed.
The results are shown in Table 2.

  As is apparent from Table 2, all of the strips of Example 1 (examples of the present invention, Nos. 1 to 10) have high tensile strength, and thus the electrode plate lattice has good flatness and lattice shape. The strip (electrode plate lattice) after the age hardening treatment was excellent in tensile strength and creep resistance. Among them, those containing any of Ag, Bi, or Tl (Nos. 8 to 10) were excellent in creep resistance (growth resistance).

  On the other hand, Comparative Example 1 (conventional material, No. 11) has a low tensile strength of the strip, so that the electrode plate lattice has poor flatness and lattice shape, and the strip after the age hardening treatment has a tensile strength. Inferior in thickness and creep resistance.

(Example 2)
No. of the composition prescribed in the present invention shown in Table 1. The lead alloy of G was melt-cast by an ordinary method to form an ingot, and this ingot was subjected to the steps of rolling → expanding → electrode grid cutting. The total rolling reduction in the rolling was variously changed within the specified values of the present invention. The tensile strength of the rolled material (strands) was examined, and the flatness and lattice shape of the electrode plate lattice were examined by the same method as in Example 1 to determine whether it was good (◯) or defective (×).

(Comparative Example 2)
A rolled material (strand) and an electrode plate lattice were manufactured under the same conditions as in Example 2 except that the total rolling reduction in the rolling was outside the specified value of the present invention (40, 98%). Investigation and judgment were performed.
The results are shown in Table 3.

  As is clear from Table 3, all the strips of Example 2 (examples of the present invention, Nos. 21 to 24) had a tensile strength of 37 to 40 MPa, and the flatness and grid shape of the electrode plate grid were good. became.

  In Comparative Example 2 (Nos. 25 and 26), the total rolling reduction was outside the specified value of the present invention, so that the tensile strength of the strip was lowered, and the electrode plate lattice was poor in flatness and lattice shape.

(Example 3)
No. used in Example 2 The electrode plate lattice cut material of No. 22 was subjected to age hardening treatment under the conditions specified in the present invention, and the tensile strength, creep resistance and active material filling property were examined, and the quality was judged.

The active material filling property was determined by the presence or absence of deformation of the electrode plate lattice after filling the active material.
That is, it was determined that a material that was not deformed at all was very good (）), a material that was deformed somewhat but that did not interfere with practical use was good (○), and a material that was deformed to an unusable level was defective (×).

(Comparative Example 3)
The same investigation and determination as in Example 3 were performed, except that the age hardening treatment was performed under conditions outside the scope of the present invention.
The results are shown in Table 4.

  As is apparent from Table 4, the electrode plate lattice after the aging treatment of Example 3 (Examples of the present invention, Nos. 31 to 34) was excellent in tensile strength, creep resistance and active material filling.

  On the other hand, the comparative example 3 No. Nos. 35 and 37 were inferior in tensile strength, creep resistance and active material filling because the age-hardening treatment temperature deviated from the specified value of the present invention. No. Since the age hardening treatment time of 36 was short, the variation in characteristics became large.

(Example 5)
No. of the composition prescribed in the present invention shown in Table 1. The lead alloy of G is melt-cast by a conventional method to form an ingot, and the ingot is rolled within a range of a total rolling reduction of 50 to 97% to obtain a strip having a thickness of 0.9 mm. It is expanded, cut into a plate grid of a predetermined size, subjected to age hardening (140 ° C. × 1.0 hour), and a positive electrode paste (active material) is applied to the plate grid by a conventional method. This was filled and aged in an atmosphere of 40 ° C. and 95% humidity for 24 hours, and then dried to obtain a positive electrode unformed sheet. Next, the negative electrode unformed plate produced by the conventional method is combined with the positive electrode unformed plate through a polyethylene separator, and further, a dilute sulfuric acid having a specific gravity of 1.200 is added to form a battery case, and D23 size, 5 hour rate A liquid lead-acid battery with a capacity of 40 Ah was manufactured.

  A life test (light load test) according to JIS D 5301 was conducted on this lead storage battery under accelerated conditions at a test temperature of 75 ° C.

(Comparative Example 5)
The lead storage battery was manufactured by the same method as in Example 5 except that the total rolling reduction was outside the scope of the present invention, and the same life test as in Example 5 was performed.

(Comparative Example 6)
No. 1 of the conventional composition shown in Table 1. The lead storage battery was manufactured by the same method as in Example 5 except that a lead alloy electrode grid of K was used, and the same life test as in Example 5 was performed.
The results are shown in Table 5.

  As is apparent from Table 5, the lead-acid battery (Nos. 41 to 45) using the electrode grid produced by the method of the present invention had a high cycle life of 5450 to 6000 times.

  On the other hand, the lead storage battery (No. 46, 47) of Comparative Example 5 has a total rolling reduction outside the specified value of the present invention, and the lead storage battery (No. 48) of Comparative Example 6 has an alloy composition of Ba. As a result, the tensile strength decreased, and as a result, expand processability, active material filling, retention, growth resistance, and the like deteriorated, resulting in a low cycle life.

  The lead storage battery after the life test was disassembled and the corrosion state of the electrode plate grid was examined, but the electrode plate grid (No. 41 to 45) manufactured by the method of the present invention showed no evidence of corrosion. Since the lead storage battery (No. 48) of Comparative Example 6 did not contain Ba in the alloy composition, the corrosion resistance decreased and partial corrosion was observed.

(Example 6)
No. of the composition prescribed in the present invention shown in Table 1. The lead alloy of I is melt-cast by a conventional method to form an ingot, and this ingot is rolled at a total reduction ratio of 86% to form a strip having a thickness of 0.9 mm, and then the strip is expanded. Is cut into an electrode plate lattice of a predetermined size, and the electrode plate lattice is subjected to age hardening (140 ° C. × 1.0 hour), and this electrode plate lattice is filled with a positive electrode paste in a usual manner, and then 40 ° C. and humidity 95 % Atmosphere for 24 hours, and then dried to obtain a positive electrode unformed sheet. Next, the negative electrode non-formed plate manufactured by the conventional method is combined with the positive electrode non-formed plate through a polyethylene separator, and further a dilute sulfuric acid having a specific gravity of 1.200 is added to form a battery case. A 36V sealed lead-acid battery with a capacity of 20 Ah was manufactured.

  The lead storage battery was subjected to a life test simulating a usage pattern in a hybrid vehicle under accelerated conditions at a test temperature of 60 ° C.

(Comparative Example 7)
No. 1 of the conventional composition shown in Table 1. The lead storage battery was manufactured by the same method as in Example 6 except that a lead alloy of K was used, and the same life test as in Example 6 was performed.
The results are shown in Table 6.

  As is clear from Table 6, the lead-acid battery (No. 51) using the electrode plate lattice produced by the method of the present invention had a high cycle life of 85,000 times.

  On the other hand, since the lead storage battery (No. 52) of Comparative Example 7 does not contain Ba in the alloy composition, the tensile strength of the electrode plate lattice is lowered, so that the retention of the active material is deteriorated or the growth is increased. The cycle life decreased due to the occurrence of corrosion or corrosion.

Claims (3)

Pb-Ca-Ba-Sn based lead alloy or a lead alloy material containing an appropriate amount of at least one of Ag, Bi, and Tl in the lead alloy is rolled and expanded with a total rolling reduction of 50 to 97%. , A method for producing a lead-acid battery electrode plate grid, comprising performing age hardening treatment in this order by heating at 80 to 160 ° C. for 0.5 hour or more. The lead alloy material is Ca 0.02 mass% or more and less than 0.05 mass%, Ba is 0.002 mass% or more and 0.014 mass% or less, and Sn is 0.4 mass% or more and 2.5 mass% or less. The method for producing a lead-acid battery plate grid according to claim 1, wherein the balance is comprised of Pb and inevitable impurities. The lead alloy material is Ca 0.02 mass% or more and less than 0.05 mass%, Ba is 0.002 mass% or more and 0.014 mass% or less, and Sn is 0.4 mass% or more and 2.5 mass% or less. Further including at least one of Ag 0.005 mass% to 0.07 mass%, Bi 0.01 mass% to 0.10 mass%, Tl 0.001 mass% to 0.05 mass%, The method for manufacturing a lead-acid battery plate grid according to claim 1, wherein the balance is made of Pb and inevitable impurities.