JP2009200020A - Lead-acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current collector of a lead-acid battery, which can enhance resistance against corrosion elongation, can suppress an early capacity drop, and can simplify a manufacturing method. <P>SOLUTION: A powder rolling current collector is used as a current collector instead of a conventional casting rolling material using a lead-calcium-tin alloy. The current collector obtained by arranging antimony powder or lead-antimony powder on the powder rolling current collector and rolling again is used. The loadings of the antimony powder or the lead-antimony powder are 0.5-5.0% to the lead powder or the lead alloy powder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to lead-acid batteries for uses such as automobile batteries, electric vehicles such as forklifts, and uninterruptible power supplies, and more particularly to a current collector for lead-acid batteries.

Lead storage batteries are inexpensive and highly reliable storage batteries, and are used in various applications such as automobile batteries, electric vehicles such as forklifts, and power supplies for uninterruptible power supplies. One of the problems that this lead storage battery has is an early capacity drop (PCL: Preliminary Capacity Loss). The early capacity reduction occurs when a passive film having no electrical conductivity such as lead sulfate (PbSO ₄ ) is formed on the surface of the current collector of the positive electrode. The early capacity reduction occurs even if lead monoxide (PbO) is generated at the contact interface between the positive electrode current collector and the reaction active material. This will be described.

In general, the surface oxide of the current collector and the reactive active material are in contact with each other at the contact interface between the positive electrode current collector and the reactive active material of the lead storage battery. Therefore, in order to improve the adhesion between the positive electrode current collector and the reaction active material, the same lead dioxide (PbO ₂ ) as the reaction active material lead dioxide (PbO ₂ ) is densely formed on the current collector surface. It is desirable.

When lead monoxide (PbO) is generated on the surface of the current collector, the adhesion (electron conductivity) between the positive electrode current collector and the reaction active material decreases. Furthermore, lead monoxide (PbO) has a high electrical resistance unlike lead dioxide (PbO ₂ ). Thus, when lead monoxide (PbO) is generated at the contact interface between the positive electrode current collector and the reaction active material, the charging current does not flow and an early capacity decrease occurs.

Therefore, it is desirable that the surface of the current collector be rapidly oxidized from lead oxide (PbO) which is a divalent (II) oxide to lead dioxide (PbO ₂ ) which is a tetravalent (IV) oxide. . That is, the current collector surface needs to be covered with lead dioxide (PbO ₂ ) as quickly as possible.

  It is known that it is effective to use an antimony-containing lead-based alloy for the positive electrode current collector as an early capacity reduction measure, and there are several research reports. For example, see Non-Patent Document 1.

According to the knowledge so far, there are mainly the following two effects of the antimony-containing lead-based alloy.
(1) Formation of α-PbO _{2 When} an antimony-containing lead-based alloy is used for the positive electrode current collector, antimony ions are eluted from the antimony-containing lead-based alloy of the current collector by the high potential of the positive electrode, and the reaction active material is dioxide dioxide. Penetration into lead (PbO ₂ ). Thereby, at the contact interface between the current collector and the reaction active material, β-PbO ₂ that is the reaction active material changes to α-PbO ₂ having a low discharge potential. Thus, when α-PbO ₂ is generated at the contact interface between the current collector and the reaction active material, the reaction active material is unlikely to discharge, and the formation of a passive film is suppressed.

(2) Electroconductive oxide, adhesion at the interface When antimony ions are eluted from the antimony-containing lead-based alloy of the current collector, lead antimony complex oxide (PbxSbyOz) at the contact interface between the current collector and the reactive active material Is generated. Since this composite oxide electronically improves the adhesion at the contact interface between the current collector and the reaction active material, the electron conductivity is increased.

  Thus, when antimony-containing lead-based alloys (Pb—Sb, Pb—Sb—Sn) are used for the positive electrode current collector, it is effective as a measure against early capacity reduction. However, since the hydrogen overvoltage of antimony is lower than the hydrogen overvoltage of lead, there is a weakness that promotes the water decomposition reaction of the electrolyte. That is, since water is reduced by the self-discharge reaction, there is a maintenance problem that the frequency of water supply must be increased in proportion to the amount of antimony added.

  A positive electrode current collector of a lead storage battery needs strength and corrosion resistance. Lead-tin-calcium (Pb-Sn-Ca) -based alloys are among the lead-based alloys having excellent strength and corrosion resistance. The lead-tin-calcium (Pb-Sn-Ca) -based alloy has less self-discharge reaction than the antimony-containing lead-based alloys (Pb-Sb, Pb-Sb-Sn), and is advantageous in terms of maintenance. However, when a lead-tin-calcium (Pb-Sn-Ca) -based alloy is used instead of the antimony-containing lead (Pb-Sb, Pb-Sb-Sn) -based alloy as the positive electrode lattice, there is a problem of early capacity reduction.

As a countermeasure against early capacity reduction, Patent Document 1 describes a lead-based alloy in which a thin film of lead-tin-antimony alloy is superposed on the surface of a lead-tin-calcium alloy that is a base material and integrated by cold rolling. The use of an alloy sheet as a current collector is described. In this technology, a lead-antimony alloy thin film is superimposed on a base material of lead-tin-calcium alloy and cold-rolled to obtain a current collector sheet of a two-layer structure. is there. In such a two-layer structure, the elution of antimony ions from the antimony-containing lead-based alloy thin film on the surface causes the generation of (1) α-PbO ₂ described above at the interface between the current collector and the reactive active material ( 2) Formation of lead antimony composite oxide (PbxSbyOz) occurs. The shape of the current collector is a so-called expanded lattice in which an incision is made in a two-layer structure alloy sheet and pulled from the left and right to form a mesh.

Patent Document 2 discloses a method in which carbon particles and an oxide (SiO ₂ , Al ₂ O ₃ , ZrO ₂ , SnO ₂ , BaPbO ₃ ) are mixed in a lead powder, and a positive electrode current collector is produced by powder metallurgy technology. It is shown.

  Patent Document 3 describes that corrosion elongation is suppressed by producing a lead-tin-antimony alloy collector that is an antimony alloy using a powder rolling technique.

T.A. Laitinen and 4 others. “The Effect of Antimony on The Anodical Behavior of Lead in Sulfur Acid Solutions I. Voltammetric Measurements. 36, No 3/4, pp. 605-614, (1991) Japanese Patent No. 3156333 JP 2005-32532 A JP 2006-66173 A

  As described above, when an antimony-containing lead-based alloy is used for the positive electrode current collector, it is effective for an early capacity reduction measure. However, an antimony-containing lead-based alloy reduces hydrogen overvoltage in proportion to the amount of antimony added and promotes self-decomposition. For this reason, it is necessary to reduce the addition amount of antimony as much as possible.

  On the other hand, in the prior art, a thin film of an antimony-containing lead-based alloy such as a lead-antimony alloy or a lead-tin-antimony alloy is laminated on an alloy containing no antimony as a so-called cladding. A current collector is formed. In this case, the corrosion elongation performance of the current collector results from the performance of the base material. In addition, it is necessary to cold-roll in order to produce an alloy thin film such as lead-antimony once and bond it again.

  An object of the present invention is to provide a current collector for a lead-acid battery that has improved corrosion elongation performance compared to the prior art, suppresses early capacity reduction, and can simplify the manufacturing method.

In the present invention, an antimony powder or a lead-antimony alloy powder is arranged on the surface of a powder rolling current collector using a lead-based alloy powder, and re-rolled to produce a positive electrode current collector.

  According to the present invention, it is an object of the present invention to provide a lead-acid battery current collector that has improved corrosion elongation performance compared to the prior art, suppresses early capacity reduction, and can simplify the manufacturing method.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples unless it exceeds the gist of the invention.
The basic configuration of the lead storage battery is shown in FIG. The lead acid battery has a negative electrode terminal 11, a positive electrode terminal 12, a positive electrode plate 13, a negative electrode plate 14, a separator 15, a battery case 16, and a battery case cover 17. In the battery case 16, sulfuric acid is stored as an electrolytic solution. Yes. A positive electrode active material paste is applied to the current collector of the positive electrode plate 13. A well-known thing may be used for a positive electrode active material, and after filling with the active material paste for positive electrodes containing lead powder, red lead, lead sulfate, an additive, etc., this can be obtained by aging and drying. The positive electrode active material becomes lead dioxide (PbO ₂ ) at the interface with the current collector due to chemical conversion.
Hereinafter, a method for manufacturing the current collector of the positive electrode plate 13 will be described. First, the material of the positive electrode current collector according to the present invention will be described. According to the present invention, lead powder or lead alloy powder is used as the lead-containing powder.
The lead-based alloy powder contains at least one alloy element of tin, calcium, antimony, barium, silver, and bismuth based on lead. The lead-based alloy powder may be a lead-tin-calcium (Pb-Sn-Ca) -based alloy, or may be a lead-tin (Pb-Sn) -based alloy powder. The lead-based alloy powder can be produced by a gas atomization method in which a molten metal is sprayed into dry air to produce a rapidly solidified powder. The lead-containing powder is formed by powder rolling into a sheet. The rolled sheet thus formed has a structure composed of crystal grains oriented in a specific direction with an aspect ratio of 3 to 13. The rolled sheet is cut into a predetermined size to form a current collector. A current collector having a lattice structure may be formed by expanding a rolled sheet.

  FIG. 2A shows a basic configuration of a powder rolling apparatus used for manufacturing a current collector according to the present invention. The powder rolling apparatus of this example includes a first hopper 21, a first belt conveyor 22, a second hopper 23, horizontally opposed first rolling rolls 24a and 24b, a third hopper 25, vertically opposed second rolling rolls 26a and 26b, and And a rolled sheet winder (not shown).

  A method for producing a rolled sheet that is a material for the current collector of the positive electrode plate 13 will be described below. In this example, the raw material powder 20 becomes a rolled sheet having a thickness of 100 μm by passing through the horizontally opposed first rolling rolls 24a and 24b. On the rolled sheet 29, antimony powder or lead-antimony powder as the second powder is supplied from the third hopper 25 and passed through the vertically opposed second rolling rolls 26a and 26b. Thereby, a rolled sheet 30 for a current collector having a thickness of 0.5 mm is obtained. The rolled sheet 30 is formed by rolling and integrating a second powder on a base material. The rolled sheet 30 thus produced is stored in a roll shape by a winder (not shown).

  With reference to FIG. 3, the manufacturing method of the positive electrode electrical power collector for lead acid batteries by this invention is demonstrated. In step S101, a lead-containing powder that is a first powder is prepared. The lead-containing powder is composed of lead powder or lead-based alloy powder. In step S102, antimony powder or lead-antimony powder which is the second powder is prepared. The lead-based alloy powder can be produced by a gas atomization method. The gas atomization method is a method of generating rapidly solidified powder by spraying molten metal into dry air.

  In step S103, a rolled sheet is generated by powder rolling the first powder. In step S104, the antimony powder or lead-antimony powder, which is the second powder, is placed on the rolled sheet generated in step S103 and re-rolled to produce a rolled sheet in which the second powder is rolled on the sheet surface. To do. The rolled sheet is produced using the powder rolling apparatus shown in FIG.

  In step S105, a current collector is formed from the rolled sheet. When producing a flat positive plate, the rolled sheet is cut into a rectangle. When creating a grid-like positive electrode plate, a rolled sheet cut into a rectangle is cut with a cutter, and both ends are pulled evenly. A positive electrode plate is formed by applying a paste of a positive electrode active material to the current collector manufactured in this manner and then aging and drying the paste.

  FIG. 4 is a photograph showing an example of the structure of a rolled sheet. Such a structure image is obtained by cutting the rolled sheet in parallel to the rolling direction and imaging the cut surface after immersing the cut surface in an etching solution. As shown in FIG. 4, the structure of the rolled sheet is composed of fine particles of gas atomized powder, which is a raw material for powder rolling, and the aspect ratio, which is the aspect ratio of the particle diameter, is 3 to 13. This is an example in which antimony powder or lead-antimony powder particles as the second powder are present near the surface of the rolled sheet.

  With reference to FIG. 5, the procedure of the experiment performed in order to evaluate the electrical power collector for lead acid batteries by this invention is demonstrated. In step S201, a positive electrode current collector was produced. In step S202, the positive electrode, the negative electrode, the separator, and the like were assembled to produce a single cell. In step S203, positive and negative electrodes were formed. In step S204, a deep discharge cycle and an overcharge test were performed. The conditions of the deep discharge cycle are shown in Table 1, the conditions of the overcharge test are shown in Table 2, and the results of the deep discharge cycle and the overcharge test are shown in Table 3.

  FIG. 6 shows an example of the structure of the current collector of the positive electrode plate used in the experiment. The flat positive electrode plate has a positive electrode active material application part 62 coated with a reaction active material and a masking part 61 masked with a sulfuric acid resistant adhesive insulating tape. The positive electrode active material application part 62 is provided with five through holes 63 having a diameter of 5 mm. This is to increase the adhesion between the positive electrode active material and the current collector during aging and to keep the coating amount constant. A lead wire 64 made of lead is soldered to the masking portion 61. The lead wire 64 serves as a connection portion with a test external power source (not shown).

Hereinafter, an example of implementation will be described.
Air-cooled gas atomized powder of lead-0.05% calcium-1.5% tin alloy with a particle size under 75 μm is prepared as the first powder, and lead by the gas atomization method with particle size of under 75 μm as the second powder— 5% antimony powder was prepared. From these powders, a rolled sheet was produced using a powder rolling apparatus shown in FIG. Further, as a comparison, a cast-rolled two-layer structure rolled sheet conventionally used was used.

The current collector of the present invention is a plate-like current collector shown in FIG. First, a rolled sheet was produced by the method shown in FIG. As described above, a gas atomized powder of lead-0.05% calcium-1.5% tin alloy as the first powder is passed through the horizontally opposed first rolling rolls 24a, 24b, thereby rolling the sheet 29 having a thickness of 1 mm. Is made. Subsequently, as a second powder, a lead-5% antimony powder having a particle size of under 75 μm is supplied to the third hopper 25 so as to be 3.0% (mass ratio) with respect to the first powder. A fixed amount of lead-antimony alloy powder is supplied from the third hopper 25 and re-rolled by the vertically opposed second rolling rolls 26a and 26b to produce a rolled sheet 30 having a thickness of 0.5 mm. Take up in a roll.
The feeding speed of the rolled sheet can be appropriately changed from 0.5 to 10 m / sec by adjusting with the post-process. Next, it cut out into plate shape from the said roll-shaped rolling sheet 30, and produced the electrical power collector shown in FIG.
The second powder may be an antimony powder by a gas atomizing method in addition to the lead-antimony alloy powder.

  The second powder is 0.5% to 5.0% (mass ratio) with respect to the first powder. This is because if the amount is less than 5.0%, the desired effect is not seen. If the amount exceeds 5.0%, the effect is saturated, and if added more than this, the maintenance performance of the lead storage battery containing antimony is lowered. It is.

  The positive electrode current collector for comparison is a current collector conventionally used, and uses lead-0.05% calcium-1.5% tin as a base material. Using the rolling device of FIG. 2 (B), a lead-5% antimony cast rolled material 32 is bonded to the base material 31 to produce a current collector 33 having a thickness of 0.5 mm, and the plate-like shape shown in FIG. A current collector was produced.

  Table 1 shows the conditions of the deep discharge cycle and the overcharge test of the experiment of this example. In the deep discharge cycle, both charging and discharging are performed at a temperature of 25 ° C. and a current of 36 mA. In the overcharge test, the temperature is 75 ° C. and the current is 3.6 mA.

  Table 2 shows the results of the product of the present invention and the comparative example in the test of Table 1. From this result, the product of the present invention exhibits superior performance in the deep discharge cycle test and the overcharge test as compared with the comparative example. In the present invention product, by rolling and integrating the lead-antimony powder into the base powder rolling current collector, the early capacity reduction is suppressed, and the active material falling off due to the corrosion deformation of the current collector is also suppressed. Thus, the deep discharge cycle test performance was improved, and the overcharge life performance was considered to be improved by the small corrosion deformation of the base powder rolling current collector.

  In this embodiment, the antimony powder or the lead-antimony powder is rolled only on one side of the rolled sheet 29. This is because only one side has a sufficient effect. Although the number of manufacturing steps is increased, when the antimony powder or the lead-antimony powder is rolled on both surfaces of the rolled sheet 29, a more remarkable effect is obtained.

It is a figure which shows the structure of a lead acid battery. (A) It is a figure which shows the structure of the powder rolling apparatus used for manufacture of the positive electrode electrical power collector by this invention. (B) It is a figure which shows the structure of the rolling apparatus used for manufacture of the conventional positive electrode electrical power collector. It is a figure explaining the manufacturing method of the positive electrode electrical power collector by this invention. It is a figure which shows the structure | tissue of the rolled sheet by this invention. It is a figure which shows the procedure of the evaluation experiment of the positive electrode electrical power collector by this invention. It is a figure which shows the positive electrode electrical power collector for evaluation by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Negative electrode terminal, 12 ... Positive electrode terminal, 13 ... Positive electrode plate, 14 ... Negative electrode plate, 15 ... Separator, 16 ... Battery case, 17 ... Battery case cover, 21 ... First hopper, 22 ... First belt conveyor, 23 ... 2nd hopper, 24a, 24b ... Horizontally opposed first rolling roll, 25 ... 3rd hopper, 26a, 26b ... Vertically opposed 2nd rolling roll, 29, 31 ... Rolled sheet, 61 ... Masking part, 62 ... Positive electrode active material application 63, through hole, 64 ... lead wire

Claims (2)

In a current collector for a positive electrode of a lead storage battery formed by powder rolling of a lead powder or a lead-based alloy powder and having a structure composed of crystal particles oriented in a specific direction with an aspect ratio of 3 to 13, an antimony is formed on the surface layer A lead storage battery characterized in that a structure obtained by rolling powder or lead-antimony powder exists. 2. The addition amount of antimony powder or lead-antimony powder forming the surface layer is 0.5% or more and 5.0% or less with respect to lead powder or lead-based alloy powder. Lead acid battery.

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