JP2015185478A - Sealed lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed lead-acid battery capable of suppressing occurence of dendrite short circuit of a base end side portion in the ear part of an electrode plate.SOLUTION: A sealed lead-acid battery 1 includes a battery case 2, and an electrode plate group 3 which is formed so that positive and negative electrode plates 4 having ear parts 5 each formed on the one side thereof are alternately laminated with a separator 7 held therebetween and the ear parts 5 of respective electrode plates 4 having the same polarity are connected to straps 8, and which is housed in the battery case 2 in a compressed state. As to the separator 7, a portion where density of the separator 7 is higher than density of other portions 7b of the separator 7 is formed at least in a portion facing the base end part of the ear part 5 of the electrode plate among portions on the same side as the side of the electrode plate 4 on which the ear part 5 is formed, in a portion of the separator 7 held between respective electrode plates 4, 4.

Description

  The present invention relates to a sealed lead-acid battery.

  Conventionally, the battery case and the positive and negative electrode plates having ears formed on one side are alternately laminated with the separator interposed therebetween, and the ears of each electrode plate of the same polarity are connected to the strap, In a sealed lead-acid battery including an electrode plate group accommodated in a compressed state in the battery case, an attempt is made to improve battery performance. For example, in Patent Document 1, a covering portion that covers the ear portion by extending the retainer (separator) to contact with the negative electrode strap is provided integrally with the retainer, and oxygen gas generated from the positive electrode side during charging is used. It is described that the abnormal corrosion of the ear portion of the negative electrode plate is suppressed.

JP-A-8-162149

  The sealed lead-acid battery of Patent Document 1 is mainly improved in battery performance from the viewpoint of extending the life, and further improved in battery performance from the viewpoint of charge acceptance performance. In order to improve the battery performance, it is common to thin the electrode plate to increase the number of sheets and pack the active material to the limit. However, the lead-acid battery has a short distance between the positive and negative electrode plates at high temperatures. It is easy to cause a dendrite short circuit by using the battery or leaving it discharged. Since the sealed lead-acid battery has a smaller amount of electrolyte than the liquid type, the amount of sulfuric acid is reduced, and the danger of a dendrite short circuit is high. In addition, in the sealed lead-acid battery, the ears of each electrode plate of the electrode plate group are integrally welded by COS (cast on strap), and at the same time, a strap, or a strap and a pole column are formed. And COS further reduces the distance between the positive and negative electrode plates from the front end side to the base end side of the ear. In addition, the base end side part of the ear | edge part is an upper lattice part of the lattice board | substrate which comprises an electrode plate. The lattice substrate is composed of an outer lattice formed from a thick lattice and an intermediate lattice formed from a thin lattice. The upper lattice portion indicates the upper portion of the outer lattice, and the upper lattice portion is a current collecting portion of electricity. In addition, since the lead dissolution and precipitation reaction is active, there is a problem that a dendrite short circuit is likely to occur at the proximal end portion of the ear portion of the electrode plate.

  The present invention has been made in view of the circumstances as described above, and an object thereof is to provide a sealed lead-acid battery capable of suppressing the occurrence of a dendrite short in the proximal end portion of the ear portion of the electrode plate. Yes.

In order to solve the above-mentioned problems, the sealed lead-acid battery of the present invention has a battery case and positive and negative electrode plates having ears formed on one side and are alternately stacked with a separator interposed between them. Each electrode plate is connected to a strap, and the electrode plate group is housed in a compressed state in the battery case. The separator is provided in a portion sandwiched between the electrode plates. The density of the separator is higher than that of the other part of the separator at least in the part facing the base end side part of the ear part of the electrode plate among the parts on the same side as the electrode plate side. It is characterized by being formed.
According to this configuration, it is possible to suppress the occurrence of a dendrite short at the base end side portion of the ear portion of the electrode plate.
In this sealed lead-acid battery, the separator has a glass fiber mat as a separator forming member, and the glass fiber mat has a base portion having a uniform thickness and a thickened portion having a thickness larger than the base portion. Preferably, the separator is formed at a high density by sandwiching the thickened portion between the electrode plates with higher compression than the base portion.
According to this configuration, the high-density portion of the separator can be easily formed.
In this sealed lead-acid battery, the thickened portion of the glass fiber mat is preferably formed by folding a glass fiber mat having a uniform thickness.
According to this structure, the glass fiber mat conventionally used as a separator formation member can be utilized as it is, and a thickened part can be formed at low cost.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the dendrite short of the base end side part of the ear | edge part of an electrode plate can be suppressed.

It is sectional drawing which showed one Embodiment of the state before the lid | cover was given of the sealed lead acid battery of this invention. It is the side view which showed the outline | summary of the structure of the electrode group of the sealed lead acid battery of FIG. It is a perspective view of the separator formation member used for the separator of the electrode group of the sealed lead acid battery of FIG. It is the perspective view which showed another embodiment of the separator formation member. It is a side view of one structural member of the electrode group of the sealed lead-acid battery of FIG.

  FIG. 1 is a cross-sectional view showing an embodiment of the sealed lead-acid battery according to the present invention before a lid is applied. FIG. 2 is a side view showing an outline of the configuration of the electrode plate group of the sealed lead-acid battery of FIG.

  As shown in FIG. 1, the sealed lead-acid battery 1 includes a synthetic resin battery case 2 and an electrode plate group 3 accommodated in the battery case 2 in a compressed (pressed) state.

  The electrode plate group 3 includes a positive and negative electrode plate 4 having an ear 5 formed on one side, a separator 7 and a strap 8, and the positive and negative electrode plates 4 are alternately sandwiched between the separators 7. It is constituted by a strap 8 formed by integrally connecting the ear portions 5 of the electrode plates 4 which are stacked and have the same polarity.

  More specifically, in FIG. 1, the positive electrode plate 4 a has ears 5 a that protrude upward on the upper left side, and the paper plates penetrate so that the ears 5 a of each positive electrode plate 4 a face each other. A plurality of sheets are arranged in the direction. The negative electrode plate 4b has an ear portion 5b protruding upward at the upper right portion, and a plurality of negative electrode plates 4b are arranged in the through-plane direction so that the ear portions 5b of each negative electrode plate 4b face each other. Each of the positive electrode plate 4a and the negative electrode plate 4b is formed by filling a positive and negative electrode active material paste on a lattice substrate containing lead as a main component. As shown in FIG. 2, a protruding portion protruding upward is formed on the upper lattice 6 of the lattice substrate, and this protruding portion constitutes an ear portion 5 of the electrode plate 4.

  The ears 5 of each electrode plate 4 of the same polarity of the electrode plate group 3 are welded together by COS (cast on strap) to form a strap 8 at the same time. The strap 8 has a positive electrode strap 8a and a negative electrode strap 8b. Each strap 8 extends in the stacking direction of the electrode plates 4 (in the drawing direction in FIG. 1), and the ear portion 5a of each positive electrode plate 4a is connected to the positive electrode strap 8a. And the ear | edge part 5b of each negative electrode plate 4b is connected to the negative electrode strap 8b. A positive pole 9a is provided on the positive strap 8a, and a negative pole 9b is provided on the negative strap 8b. The sealed lead-acid battery 1 has a single cell structure and is connected to a pole column, but may have a structure having a plurality of cells. If it is not a single cell structure, the pole columns are not necessarily connected.

  The separator 7 uses a porous member as a separator forming member, absorbs and holds the electrolyte, and prevents a short circuit between the positive electrode plate 4a and the negative electrode plate 4b. In this embodiment, it is set as the structure which has the part 7a formed in high density in part. That is, the separator 7 is at least the base end side of the ear part 5 of the electrode plate 4 among the parts on the same side as the electrode plate 4 side where the ear part 5 is formed in the part sandwiched between the electrode plates 4 and 4. The density of the separator 7 is formed at a higher density than the other part 7 b of the separator 7 in the part facing the part. Here, “density” refers to bulk density. The “other part 7b” refers to a part of the separator 7 other than the part 7a formed with high density. The separator 7 is formed of a porous member made of the same material in the portion 7a and the other portion 7b that are formed with high density. Therefore, “formed with high density” means that the bulk density is high, the density is high, and the porosity is low.

  As a porous member which is a separator formation member, what was conventionally used as a separator of a sealed lead acid battery is employable. For example, a glass fiber mat in which fibers mainly composed of glass fibers are formed in a mat shape can be given. Such a separator using a glass fiber mat is also called an AGM (Absorbed Glass Mat) separator. Examples of materials other than glass fiber mats include porous synthetic resins.

  A portion 7 a formed at a high density in the separator 7 is a portion facing the proximal end portion of the ear portion 5 of the electrode plate 4. The base end side portion of the ear portion 5 is a portion where a protruding portion is formed in the upper lattice 6 of the lattice substrate (a boundary portion between the ear portion 5 and the upper lattice 6) or a portion including the periphery thereof. Therefore, the portion 7a formed at a high density in the separator 7 is a portion facing a portion where the protruding portion is formed in the upper lattice 6 of the lattice substrate or a portion including the periphery thereof. In FIG. 1, a portion of the electrode plate 4 that faces the proximal end portion of the ear portion 5 is indicated by a symbol A.

  The portion 7a formed with high density may extend over the entire portion on the same side as the side of the electrode plate 4 on which the ear portion 5 is formed in the portion sandwiched between the electrode plates 4 and 4. In FIG. 1, the portions indicated by reference characters A and B are portions 7 a formed with high density, and the upper portion of the separator 7 sandwiched between the electrode plates 4, 4 is the width direction (left and right direction on the paper). ) It is formed with high density over the entire length. The portion 7a formed at such a high density may be formed from the upper end of the separator 7 to a middle position in the height direction (the vertical direction in the drawing in FIG. 1).

  The density of the other portion 7b of the separator 7 is approximately the same as that of the separator of the conventional sealed lead-acid battery. Therefore, the density of the portion 7a formed in the separator 7 at a high density is higher than that of the separator of the conventional sealed lead-acid battery. The upper limit value of the density of the portion 7a formed at a high density can be set to twice the density of the other portion 7b from the viewpoint of manufacturing and the amount of electrolyte retained. In addition, the glass fiber mat conventionally used as the separator forming member in the sealed lead-acid battery has a fiber density of 0.12 to 0.19 g / cm 3.

  Since the portion 7a formed at a high density has a higher density and a lower porosity than the other portion 7b formed of the same material, a dendrite short at the proximal end portion of the ear portion 5 of the electrode plate 4 Can be suppressed. Since the other part 7b of the separator 7 has a density comparable to that of a conventional lead-acid battery separator, the electrolyte can be sufficiently retained and battery performance such as discharge capacity and cycle life can be ensured. it can.

  The sealed lead-acid battery 1 of this embodiment can be obtained, for example, as follows. A sealed lead-acid battery using a glass fiber mat as a separator forming member will be described below.

First, as shown in FIG. 3, a glass fiber mat 10 a configured to have a base portion 12 having a uniform thickness and a thickened portion 11 thicker than the base portion 12 is used as the separator forming member 10. prepare. This glass fiber mat 10a is long, and the end portions on both sides in the longitudinal direction are thick. The thick portion is the thickened portion 11, and the other thin portion is the base portion 12. The base portion 12 has a basis weight (fiber density) comparable to that of a glass fiber mat conventionally used as a separator forming member in a sealed lead-acid battery. The thickened portion 11 can be formed by setting the fiber density higher than that of the base portion 12. Before the electrode plate group 3 is formed, the thickened portion 11 can be pressure-bonded so as to have the same thickness as the base portion 12.
Note that the thickness of the thickened portion 11 is preferably about 1.5 to 2 times the thickness of the base portion 12 because the insertability of the electrode plate group into the battery case decreases.

  In order to form the thickened portion 11 more simply, as shown in FIG. 4, the end portions on both sides in the longitudinal direction of the glass fiber mat 10a having a uniform thickness that have been used in the past are folded and the folded portions are overlapped. It is preferable to form the thickened portion 11 together. A glass fiber mat piece obtained by cutting a glass fiber mat that has been used in the past into a slender shape is prepared separately, and the glass fiber mat pieces are end portions on both sides in the longitudinal direction of a glass fiber mat having a uniform thickness that has been conventionally used. The thickened portion may be formed so as to overlap the portion. These methods are low in cost because a glass fiber mat conventionally used as a separator forming member can be used. After the glass fiber mats 10a are overlapped, the overlapped portion can be integrally formed by pressure bonding or adhesion.

Next, as shown in FIG. 5, the glass fiber mat 10 a prepared as described above is folded in two so that the thickened portion 11 comes outside, and is wrapped from the lower end of the electrode plate 4 so as to be covered on both sides. It arranges in. The thickened portion 11 of the glass fiber mat 10 a is disposed at a position facing the upper portion of the electrode plate 4 including the proximal end portion of the ear portion 5. In this way, one constituent member of the electrode plate group 3 is obtained. In FIG. 5, the thickened portion 11 is folded in two so that it comes to the outside, but it can also be folded in half so that this thickened portion 11 comes inward. Further, in this embodiment, the glass fiber mat 10a whose end portions on both sides in the longitudinal direction are the thickened portions 11 is folded in half to wrap the electrode plate 4, but the leaf whose one end portion is the thickened portion. Alternatively, the electrode plate 4 may be sandwiched between two glass fiber mats. In addition, either the positive electrode plate or the negative electrode plate is accommodated in the glass fiber mat 10a folded in half.
Finally, positive and negative electrode plates 4 are alternately laminated via glass fiber mats 10a, and the ears 5 of each electrode plate 4 of the same polarity are connected together to form a strap 8 to form FIG. An electrode plate group 3 as shown in FIG.

  Next, the electrode plate group is housed in the battery case in a state compressed (squeezed) with a predetermined pressure in the stacking direction. FIG. 1 shows a sealed lead-acid battery in this state. Since the thickened portion of the glass fiber mat is thicker than the base portion, the thickened portion is sandwiched between the electrode plates at a higher compression than the base portion in the electrode plate group in a compressed (compressed) state. . The compressed (pressed) thickened portion is formed at a higher density than the base portion, and this portion constitutes a portion formed at a higher density in the separator of the sealed lead-acid battery. The base part of the glass fiber mat constitutes another part in the separator of the sealed lead-acid battery. In this case, since it is not necessary to press-press the thickened portion in advance, this step can be omitted. On the other hand, when the pressure bonding is performed so that the thickened portion of the glass fiber mat has the same thickness as the base portion before forming the electrode plate group, the electrode plate group is accommodated in the battery case. In this case, the thickened portion is not subjected to higher pressure than the base portion, and the group insertion property to the battery case of the electrode plate group can be improved.

  Next, the lid is attached to the battery case by welding or adhesion. Thereafter, a dilute sulfuric acid electrolyte solution having a predetermined concentration is poured into the battery case from the opening provided in the lid, and the battery case is formed, and a valve is covered over the opening to obtain a sealed lead-acid battery.

  The separator of the sealed lead-acid battery obtained as described above has at least the ear portion of the electrode plate in the portion on the same side as the electrode plate side where the ear portion is formed in the portion sandwiched between the electrode plates. Since the density of the separator is formed higher in the part facing the base end part than in the other part of the separator, the occurrence of a dendrite short in the base end part of the ear part of the electrode plate is suppressed. Can do.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, the separator can be shaped and sized to cover the ears of the electrode plate. Thereby, abnormal corrosion of the ear portion of the negative electrode plate can be suppressed.

DESCRIPTION OF SYMBOLS 1 Sealed lead acid battery 2 Battery case 3 Electrode plate group 4 Electrode plate 5 Ear | edge part 7 Separator 7a The part formed in high density 7b Other parts (parts other than the part formed in high density)
8 Strap 10 Separator forming member 10a Glass fiber mat 11 Thickened portion 12 Base portion

Claims (3)

A battery case and positive and negative electrode plates each having an ear formed on one side are alternately stacked with a separator interposed therebetween, and the ears of each electrode plate having the same polarity are connected to a strap, and the battery case An electrode plate group accommodated in a compressed state therein,
The separator is a portion facing at least a base end side portion of the ear portion of the electrode plate among portions on the same side as the electrode plate side where the ear portion is formed in a portion sandwiched between the electrode plates. Further, the sealed lead-acid battery is characterized in that the density of the separator is higher than that of the other part of the separator.   The separator includes a glass fiber mat as a separator forming member, and the glass fiber mat includes a base portion having a uniform thickness and a thickened portion thicker than the base portion. 2. The sealed lead-acid battery according to claim 1, wherein the separator is formed at a high density by being sandwiched between the electrode plates with higher compression than the base portion. The sealed lead-acid battery according to claim 2, wherein the thickened portion of the glass fiber mat is formed by folding a glass fiber mat having a uniform thickness.

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