JP2018060615A - Lead-acid battery and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead-acid battery preventing a strap from being corroded.SOLUTION: A lead-acid battery of an embodiment of the present invention includes: an electrode plate group including a plurality of positive electrode plates and a plurality of negative electrode plates alternately stacked with a separator interposed therebetween; and a strap welded to ear portions of a plurality of electrode plates of the same polarity in the electrode plate group. At least a part of the surface of the strap is covered by a porous body containing lead as a main component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lead storage battery and a method for manufacturing the same.

  A lead-acid battery includes a group of electrode plates in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately stacked via separators, and a plurality of same polarity electrode plates in the electrode plate group are members called straps. Is electrically connected. With respect to this strap, there has been reported a problem that it corrodes while using a lead storage battery (for example, Patent Documents 1 and 2).

  Patent Document 1 discloses a technique for preventing corrosion of a negative electrode strap by providing a gel-like body obtained by mixing silica in an electrolytic solution from the upper surface of the negative electrode strap to the electrode plate group. Further, Patent Document 2 is provided with an electrode plate group in which the outer surface of the sulfuric acid holding layer adhered to at least the upper surface of the negative electrode strap is covered with a synthetic resin cover having a U-shaped cross section that covers the negative electrode strap. Technology is disclosed. All of these are techniques for preventing the strap of the negative electrode from being oxidized and corroded by oxygen gas generated from the positive electrode when the amount of the electrolyte is small.

JP 2002-134159 A JP 2001-273882 A

  However, the inventor of the present application has found that even if the techniques disclosed in Patent Documents 1 and 2 are employed, corrosion of the strap of the negative electrode may not be prevented.

  This invention is made | formed in view of this point, The place made into the objective is to provide the lead storage battery which prevents the corrosion of a strap.

  A lead storage battery according to an aspect of the present invention includes an electrode plate group in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately stacked via a separator, and a plurality of electrode plates of the same polarity in the electrode plate group. A strap welded to the ear portion, and at least a part of the surface of the strap is covered with a porous body mainly composed of lead. To have lead as a main component means that the content of lead is 50% by mass or more.

  A method for producing a lead-acid battery according to one aspect of the present invention includes a group of electrode plates in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately stacked via separators, and a plurality of the same polarity in the electrode plate group. A lead-acid battery manufacturing method comprising a strap welded to an ear portion of an electrode plate, wherein the electrode plate group is formed, and the ear portion of each of the electrode plates of the same polarity is It comprises a structure including welding the strap and covering at least a part of the surface of the strap with a porous body mainly composed of lead after the welding.

  In the lead-acid battery according to one embodiment of the present invention, since at least a part of the surface of the strap is covered with a porous body mainly composed of lead, corrosion of the strap caused by minute cracks can be prevented. .

It is an exploded view showing typically the internal structure of a lead acid battery concerning an embodiment. It is a typical perspective view of the strap concerning an embodiment. It is a graph showing the result of the corrosion acceleration test which concerns on embodiment.

  Before describing the embodiment, the background to the present invention will be described.

  When welding a strap and an ear | edge part, a micro crack may arise in a strap depending on conditions. Since the cracks are minute and rarely occur, it is difficult to find the cracks. However, corrosion progresses from this crack, and the strap may break. Since cracks rarely occur, the countermeasures against such corrosion have not been sufficiently taken, and the inventors of the present invention have found that the techniques of Patent Documents 1 and 2 cannot prevent this corrosion.

  The inventor of the present application infers the phenomenon of corrosion caused by cracks as follows. When micro cracks exist in the strap inside the battery, since the sulfuric acid concentration and the oxygen concentration are low in the internal space of the crack, the passive state such as lead sulfate is difficult to be generated, and metallic lead dissolves and lead ions are generated. In other words, cracks expand and corrosion spreads. And the lead ion produced | generated inside the crack moves to the crack entrance vicinity, reacts with sulfuric acid, and becomes lead sulfate. This phenomenon cannot be suppressed by the techniques disclosed in Patent Documents 1 and 2, and the progress of corrosion in which cracks expand cannot be stopped.

  Therefore, as a result of various investigations to suppress this corrosion, the present inventor has come up with the present invention.

  One aspect of the present invention is to weld a plate group formed by alternately laminating a plurality of positive electrode plates and a plurality of negative electrode plates via separators, and a plurality of same polarity electrode plates in the electrode plate group. A lead storage battery in which at least a part of the surface of the strap is covered with a porous body mainly composed of lead. The porous body retains the electrolytic solution and can suppress the progress of corrosion of cracks.

  Here, the average pore diameter of the porous body may be configured to be 0.1 μm or more and 20 μm or less. With such a configuration, the electrolyte can be sufficiently retained in the porous body.

  The surface of the strap may be provided with a roughened surface. With such a configuration, the porous body is firmly held by the strap.

  Another aspect of the present invention is an electrode plate group formed by alternately laminating a plurality of positive electrode plates and a plurality of negative electrode plates with separators interposed therebetween, and an ear portion of a plurality of the same polarity electrode plates in the electrode plate group. A method of manufacturing a lead-acid battery comprising a welded strap, wherein the strap is welded to each ear of each of the plurality of same polarity plates, and after the welding, Covering at least a part of the surface of the strap with a porous body mainly composed of lead.

  In the case as described above, since the porous body mainly composed of lead covers at least a part of the surface of the strap, the electrolytic solution is held in the pores of the porous body.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

(Embodiment)
FIG. 1 is a schematic exploded view in which internal members are taken out and separated to show the internal structure of the lead-acid battery according to the embodiment. In the lead storage battery according to the present embodiment, an electrode plate group 4 formed by alternately laminating a plurality of positive electrode plates 1 and a plurality of negative electrode plates 2 via separators 3 is accommodated in a battery case 11. The opening is sealed with a lid 12. An electrolytic solution (not shown) is placed in the battery case 11.

  In the electrode plate group 4, each positive electrode plate 1 is provided with an ear portion 1 a that is a protruding portion, and these ear portions 1 a are welded to and connected to a strap 5. A pole 5a is provided on the surface of the strap 5 opposite to the surface connected to the ear 1a. The pole 5a is electrically connected to a positive terminal provided on the lid 12. Further, each of the negative electrode plates 2 is also provided with ear portions 2 a as in the case of the positive electrode plate 1, and these ear portions 2 a are welded to the strap 6 and connected to each other. Also in the negative electrode, the pole 6a is provided on the surface of the strap 6 opposite to the surface connected to the ear 2a, and the pole 6a is electrically connected to the negative terminal provided on the lid 12. Connected. A porous body 30 (shown by cross-hatching) is provided on a part of the surface of the strap 6.

  As shown in FIG. 2, the upper surface (surface opposite to the surface connected to the ear portion 2 a), the side surface, and the lower surface of the portion connected to the ear portion 2 a of the negative strap 6 are formed by the porous body 30. It is covered. Since the lower surface is a surface that cannot be seen in FIG. 2, the porous body 30 on the lower surface is not shown. Here, the negative electrode plate existing below the ear 2a is omitted and not shown. The porous body 30 is made of a substance containing lead as a main component.

  In the method for manufacturing a lead-acid battery according to the present embodiment, a plurality of positive electrode plates 1, a plurality of negative electrode plates 2, and a plurality of separators 3 are prepared to form an electrode plate group 4. The positive strap 5 is welded, and the negative strap 6 is welded to the ear portion 2a of each negative electrode plate 2. Thereafter, the upper surface, the side surface, and the lower surface of the strap 6 are covered with a porous body 30 mainly composed of lead. It has a process called.

  The lead storage battery according to this embodiment will be described more specifically below.

  In the present embodiment, lead powder is used as the positive electrode active material. Lead powder, which is a powder containing lead metal oxide as a main component and containing metallic lead, is prepared by an appropriate method such as a ball mill method, a harding method, or a Burton pot method. The lead powder may contain red lead. The lead powder is filled in a Pb—Sb-based positive electrode grid, immersed in dilute sulfuric acid, and then dried in air to obtain an unformed positive electrode plate 1. The kind of the lead powder is arbitrary, and a known additive such as a synthetic fiber reinforcing agent or Sn may be added to the lead powder.

  The negative electrode according to this embodiment is prepared as follows. Lead powder, barium sulfate, carbon black, and synthetic fiber reinforcing material are kneaded with water and sulfuric acid to form a negative electrode active material paste, and this negative electrode active material paste is filled into a cast lattice made of a Pb-Sb alloy, and dried. Aging is performed to obtain an unformed negative electrode plate. The negative electrode active material paste may contain components other than those described above.

  After alternately laminating the plurality of positive electrode plates 1 and negative electrode plates 2 produced as described above, the respective ear portions 1a of the plurality of unformed positive electrode plates 1 are connected to the strap 5 made of lead by welding, A combined body of the positive electrode plates 1 is produced. And each ear | edge part 2a of several sheets of unformed negative electrode plates 2 is connected to the strap 6 which consists of lead by welding, and the assembly body of the unformed negative electrode plates 2 is produced.

  Further, a paste prepared by adding lead powder, water and sulfuric acid to the surface of the strap 6 and applying the paste is dried. When the moisture disappears, the surface of the strap 6 is covered with the porous body 30 mainly composed of lead. Various other additives such as a synthetic fiber reinforcing material and lignin may be added to the paste.

  The porous body preferably covers at least a portion of the surface of the strap that is welded to the ear portion. Since cracks are likely to occur in places where stress is applied or where the heat capacity is large when the strap is welded to the ear portion and cooled, it is preferable to cover at least a place where such cracks are likely to occur with a porous body. Moreover, it is preferable that the thickness of the said porous body in the surface of a strap is 0.5 mm or more. When a paste prepared by adding water and sulfuric acid to kneaded lead powder and synthetic fiber reinforcing material as a raw material of the porous body 30 is used, this paste is originally a substance that can be put inside the lead storage battery. Is less likely to adversely affect Moreover, the intensity | strength of the porous body 30 improves by adding a synthetic fiber reinforcement to a paste.

  The surface of the strap 6 may be roughened by pressing a rough member against the strap surface after welding, or by scrubbing with a metal having high hardness. Due to the roughening, the adhesion between the porous body 30 and the strap 6 is increased. The average pore diameter of the porous body 30 covering the surface of the strap 6 is preferably 0.1 μm or more and 20 μm or less. When the average pore diameter is 0.1 μm or more, the electrolyte solution is likely to enter the pores of the porous body 30, so that the possibility that the amount of the electrolyte solution held in the porous body 30 becomes insufficient can be reduced. Further, when the average pore diameter is 20 μm or less, the electrolyte does not come out as soon as the electrolyte enters the pores of the porous body 30, and the amount of the electrolyte retained in the porous body 30 is insufficient. This is preferable because it can reduce the risk of becoming.

  Next, in a composite of a plurality of unformed negative electrode plates, the negative electrode plate is wrapped in a microporous separator, set in a battery case together with a composite of unformed positive electrode plates, and an electrolytic solution made of sulfuric acid is added to the battery. The tank is formed into a clad lead-acid battery with 2 V output and a 5-hour rate capacity of 565 Ah. The electrolytic solution may contain known additives such as aluminum ions, sodium ions, and lithium ions.

  In the lead storage battery according to the present embodiment, most of the porous body 30 covering the strap 6 is converted to lead by chemical conversion. Then, when the lead storage battery is used, the electrolytic solution is held in the porous body 30 and oxygen is consumed in the porous body 30 portion. Even if cracks exist in the strap 6, the thickness of the porous body 30 prevents the movement of oxygen and ions to the crack side, so that corrosion due to charge / discharge reaction inside the cracks is prevented. Furthermore, the formation of lead sulfate at the opening of the crack is also suppressed.

  In order to suppress crack corrosion, it is important that the electrolyte is sufficiently retained in the porous body 30. Therefore, the average pore diameter of the porous body 30 is preferably 0.1 μm or more and 20 μm or less. Further, it is preferable that the thickness of the porous body is 0.5 mm or more because oxygen is sufficiently consumed in the porous body 30 and oxygen and ions are prevented from moving to the crack side.

  What is necessary is just to measure the average hole diameter of the porous body 30 by the pore distribution by the mercury intrusion method etc., for example. The mercury intrusion method uses a phenomenon in which mercury is intruded from a large pore to a small pore by applying pressure. This measurement is performed using a pore distribution measuring device. In addition, when measurement is difficult by the mercury intrusion method, a method of measuring the pore diameter using SEM or the like can be considered. In this case, it is difficult to know the average pore diameter, but the approximate pore diameter can be known. Specifically, the average pore diameter of the porous body 30 was measured in a pore diameter range of 170 to 0.0055 μm using an automatic porosimeter manufactured by Shimadzu Corporation, Autopore IV9505 at a contact angle of 130 ° and a surface tension of 484 dyn / cm. .

(Example)
Synthetic resin fibers were added to the lead powder produced by the ball mill method, and water and dilute sulfuric acid were added to make a paste, which was then filled into a positive electrode grid made of a lead alloy and aged and dried to obtain an unformed positive electrode plate. In addition, synthetic resin fibers, barium sulfate, carbon black, and lignin are added to the lead powder produced by the ball mill method, and water and dilute sulfuric acid are added to form a paste. To give an unformed negative electrode plate.

  Prepare 11 unformed negative electrode plates and 10 unformed positive electrode plates, wrap the negative electrode plate with a separator made of polyethylene, store it in the battery case, and weld the ears of the upper part of the negative electrode plate to the straps A negative electrode plate group was formed, and the ears at the upper part of the positive electrode plate were welded to a strap to form an unformed positive electrode plate group. In preparing the negative electrode plate group, a part of the strap of the negative electrode was quenched to cause fine cracks in the strap.

  On the surface of the negative electrode strap, a synthetic resin fiber, barium sulfate, carbon black, and lignin are added to lead powder produced by the ball mill method, and a paste prepared by adding water and dilute sulfuric acid is applied. Formed body. The porous body is adjusted by changing the average pore size by changing the moisture content and drying speed of the paste. The average pore size is as follows: Example 1: 0.1 μm, Example 2: 1 μm, Example 3: 10 μm, Example 4: 20 μm, Comparative Example 1: 0 (no porous body), Comparative Example 2: 0.05 μm, and Comparative Example 3: 50 μm. The thickness of the porous body was 1 mm.

  The battery case was covered, the pole column and the electrode terminal were connected, dilute sulfuric acid was poured into the battery case as an electrolyte, and the battery case was formed in a 25 ° C. water tank to obtain a lead storage battery. The material and manufacturing method of the positive and negative grids are arbitrary, and the lead powder is not limited to the one based on the ball mill method, but may be one based on the Barton method or the like, and the content of the lead tan is arbitrary. Further, the amount and type of additives to the lead powder, the content of impurities, etc. are arbitrary. Each sample was produced under the same conditions except for the porous body covering the negative strap.

  The following corrosion acceleration test was performed on the manufactured lead acid battery.

  Simulates running of a real vehicle, repeats 317 times a discharge pattern of 0.7 seconds for 5 seconds, 0.25 CA for 8 seconds, and rest 9 seconds, then charges about 120% of the discharged electricity The discharge-charging cycle of performing was repeated until the lead-acid battery could not be charged / discharged.

  Thereafter, the lead storage battery was disassembled, and it was confirmed that charging / discharging could not be performed due to the breaking of the strap.

  As shown in FIG. 3, when the average pore diameter of the porous body is 0.1 μm, the period until the strap breaks is increased by 10% compared to Comparative Example 1 in which the porous body is not formed, and the average pore diameter is 10 μm (Comparative Example 1 Up to 35%), the period until fracture increased as the average pore size increased. When the average pore diameter exceeded 10 μm, the period until rupture gradually decreased, and when the average pore diameter reached 20 μm, the period until rupture of the strap increased by 15% of Comparative Example 1. And when the average hole diameter was 50 μm, the strap broke in the same period as in Comparative Example 1. When the average pore diameter exceeds 10 μm and reaches 20 μm, the period until the strap breaks is an increase of 10% or more of Comparative Example 1.

(Other embodiments)
The above-described embodiment is an exemplification of the present invention, and the present invention is not limited to these examples, and these examples may be combined or partially replaced with known techniques, common techniques, and known techniques. Also, modified inventions easily conceived by those skilled in the art are included in the present invention.

  The lead storage battery may be a liquid type, a control valve type, or any type. The method of the positive electrode plate is not particularly limited, and may be a paste type instead of a clad type.

  There may be a plurality of electrode plate groups. That is, a plurality of electrode plate groups may be accommodated in one battery case, and in that case, it is preferable to divide the inside of the battery case for each electrode plate group.

  The shape of each member of the lead storage battery is not limited to the shape of the above-described embodiment, and may be, for example, a known lead storage battery member shape and a modified shape easily conceived by those skilled in the art.

  The method of creating the strap is not limited to that of the above-described embodiment, and may be a method of cooling by immersing the ear in molten lead, for example.

  Further, when the porous body is provided on the lower surface of the strap, the porous body may cover part of the ears of the electrode plate at the same time.

  The porous body may be formed on the surface of the positive strap.

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 1a Ear part 2 Negative electrode plate 2a Ear part 3 Separator 4 Electrode board group 5 Strap 6 Strap 30 Porous body

Claims (4)

An electrode plate group formed by alternately laminating a plurality of positive electrode plates and a plurality of negative electrode plates via separators;
A strap welded to the ears of a plurality of electrodes of the same polarity in the electrode group,
A lead acid battery, wherein at least a part of the surface of the strap is covered with a porous body mainly composed of lead.   The lead acid battery according to claim 1, wherein an average pore diameter of the porous body is 0.1 µm or more and 20 µm or less.   The lead acid battery according to claim 1 or 2, wherein a surface of the strap is roughened. A plate group formed by alternately laminating a plurality of positive plates and a plurality of negative plates via separators, and a strap welded to the ears of a plurality of the same polarity plates in the plate group. A method for producing a lead-acid battery,
Welding the strap to each ear of the plurality of polar plates of the same polarity;
A method of manufacturing a lead-acid battery, comprising: covering at least a part of the surface of the strap with a porous body mainly composed of lead after the welding.

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