JP2005044675A - Sealed type lead-acid storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed type lead-acid storage battery in which life prolongation can be achieved, in which sulfation which occurs at a negative electrode plate surface is suppressed, and in which a low temperature rapid discharge characteristic is maintained for a long time, by preventing the generation of a short circuit due to the growth of dendrite possessed by the sealed type lead-acid storage battery. <P>SOLUTION: In the sealed type lead-acid storage battery having a group of electrode plates in which the negative electrode plate, a separator, and a positive electrode plate are laminated, the separator is the laminated type separator which has such a structure that a porous synthetic resin film is pinched from both sides by a felt state separator of which the main component is glass fiber, in which a space volume of the felt state separator contacted with the positive electrode plate of the laminated type separator is smaller than that of the felt state separator contacted with the negative electrode plate, and in which the space volume of the positive electrode plate is larger than that of the negative electrode plate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sealed lead-acid battery that has excellent short-circuit resistance and maintains low-temperature rapid discharge characteristics over a long period of time.

  In recent years, sealed lead-acid batteries that do not require maintenance and have a long service life are expected to be applied to HEV (42V system) main power supplies, auxiliary equipment, backup power supplies, and the like in in-vehicle applications such as automobiles. In industrial applications, demand is increasing in the fields of IT-related cycle use and standby use.

  Such a sealed lead-acid battery has a structure in which an electrolytic solution is impregnated into a felt-like separator mainly composed of glass fiber, and an electrode plate group is formed by combining it with a negative electrode plate and a positive electrode plate, and sealed in a sealed container. It has become. The felt separator is made of a glass fiber having a diameter of several microns processed into a mat having a thickness of about 1 to several mm from the viewpoint of wettability with the electrolyte and retention of the electrolyte.

  However, in the sealed lead-acid battery using the felt separator, first, dendrite due to lead deposition is generated in the negative electrode plate, and the dendrite grows and penetrates the felt separator. As a result, there is a problem of short-circuiting the positive electrode plate and shortening the life of the sealed lead-acid battery. Secondly, the discharge capacity of the sealed lead-acid battery depends largely on the diffusibility of sulfate ions in the electrolyte. However, in the sealed lead-acid battery, the electrolyte is retained in the separator, so It is difficult to move, and in the latter half of the discharge, sulfate ions are depleted and the discharge voltage is reduced.

  For this first problem, a sealed lead-acid battery as in Patent Document 1 with an improved separator structure has been proposed. The separator has a three-layer structure in which a microporous film made of polyethylene resin or polypropylene resin is disposed at the center, and separators for retaining the electrolyte solution are disposed on both sides thereof. And the liquid retention amount of the separator in contact with the negative electrode plate is larger than that of the separator on the positive electrode side.

  For the second problem, a sealed lead-acid battery of Patent Document 2 has been proposed. In the sealed lead-acid battery, the problem is solved by increasing the amount of electrolyte held in the positive electrode plate and the negative electrode plate by holding the positive electrode plate more than the negative electrode plate.

JP 2001-68086 A JP 11-339843 A

  However, despite the improvement by the prior art, (1) Osmotic short circuit due to dendrite growth, (2) Oxygen gas generated in the positive electrode during charging moves in the separator and is reduced on the negative electrode plate surface. Further solutions to essential problems in sealed lead-acid batteries such as the progress of sulfation that occurs in the surface layer of the negative electrode plate due to the recombination reaction are desired.

  The occurrence of the two problems is reciprocal. That is, in the process in which oxygen gas generated on the surface of the positive electrode plate during charging moves inside the separator, the pressure causes the distribution of glass fibers in the separator to become dense, which also affects the distribution of the electrolyte and creates a bias. Let As a result, a local increase in current density promotes polarization and causes sulfation in the surface layer of the negative electrode plate. As a result, the rapid charge / discharge characteristics at a low temperature are significantly deteriorated. In addition, this local bias in current density also encourages the formation of dendrites and induces the occurrence of short circuits.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a sealed lead-acid battery that prevents short-circuiting due to dendrite growth, extends its life, and maintains low-temperature rapid discharge characteristics over a long period of time.

  According to the first aspect of the present invention, in the sealed lead-acid battery having an electrode plate group in which a negative electrode plate, a separator, and a positive electrode plate are laminated, the separator has a porous synthetic resin film on the core, and glass is formed from both sides thereof. A laminated separator having a laminated structure sandwiched between felt-like separators mainly composed of fibers, wherein the spatial volume of the felt-like separator in contact with the positive electrode plate of the laminated separator is such that the felt-like separator in contact with the negative electrode plate It is a sealed lead-acid battery characterized in that it is smaller than the space volume and the space volume of the positive electrode plate is larger than the space volume of the negative electrode plate.

  The invention according to claim 2 is characterized in that two or more felt separators sandwiching a porous synthetic resin film from both sides are arranged on at least one side of the porous synthetic resin film. The sealed lead-acid battery according to 1.

  The invention according to claim 3 is the sealed lead-acid battery according to claim 1 or 2, wherein the felt-like separator includes a heat-fusible synthetic fiber.

  The invention according to claim 4 is characterized in that the porous synthetic resin film is made of polyethylene or polypropylene, has a pore diameter of 0.1 μm or less, and a film thickness of 0.03 to 0.5 mm. The sealed lead-acid battery according to any one of 1 to 3.

  According to the present invention, a short-circuit phenomenon that is fatal to a sealed lead-acid battery is suppressed, and low-temperature rapid discharge performance is maintained for a long period of time. The sealed lead-acid battery used in the transport field of automobiles and the industrial field such as IT Greatly improve. Therefore, there is an industrially remarkable effect.

  In the present invention, a laminated separator having a laminated structure in which a porous synthetic resin film is sandwiched between felt separators mainly composed of glass fibers from both sides thereof is used, and the space of the felt separator in contact with the positive electrode plate of the laminated separator is used. The above problem is solved by providing an electrode plate group configuration in which the volume is made smaller than the space volume of the felt-shaped separator in contact with the negative electrode plate and the space volume of the positive electrode plate is made larger than the space volume of the negative electrode plate.

  In other words, sandwiching a porous synthetic resin film with a felt-like separator limits the permeation amount of oxygen gas generated in the positive electrode plate, thereby preventing the glass fiber from being biased and thus suppressing the uneven distribution of current density. The

  Furthermore, the spatial volume of the felt separator in contact with the positive electrode plate in the multilayer separator according to the present invention is smaller than the spatial volume of the felt separator in contact with the negative electrode plate, and the spatial volume of the positive electrode plate is larger than the spatial volume of the negative electrode plate. In order to charge and discharge efficiently, the electrolyte solution is distributed. That is, since the surface of the positive electrode plate is covered with lead sulfate that is generated during discharge and the electrolyte solution outside the positive electrode plate cannot be used, it is necessary to hold a large amount of electrolyte solution in the positive electrode plate. This is not the case with the negative electrode plate, and discharge is performed using the outer electrolyte. Therefore, it is necessary to hold a lot of electrolyte in the felt separator on the negative electrode plate side.

  The porous synthetic resin film shows the effect of preventing the occurrence of short circuits by preventing the growth of lead dendrite by fine pores, and the average pore size is particularly preferably 0.1 μm or less, and the average pore size is 0.1 μm. When it exceeds, the effect will fall. Moreover, if the film thickness is thin, the growth of dendrites cannot be suppressed, and if it is too thick, the discharge performance is impaired, so a thickness of 0.03 to 0.5 mm is good. As the material, polyethylene, hydrophilic polypropylene, or the like is used. Note that the provision of the porous synthetic resin film has a great effect of suppressing a short circuit caused by punctures such as irregularities on the surface of the electrode plate and fragments of the active material.

  A felt-type separator sandwiching a porous synthetic resin film is usually composed of two sheets of one sheet on each side, but may be configured by stacking two or more felt-shaped separators on at least one side. In particular, by stacking two or more felt separators on the side of the negative electrode plate where dendrites are generated, the generation and growth of dendrites can be further suppressed, which is more effective. Further, when the felt-like separator contains heat-fusible synthetic fibers, the felt-like separator and the porous synthetic resin film are heat-sealed in a laminated state, and the above-mentioned effects can be further enhanced and the manufacturing process can be performed. Handleability can be improved.

Hereinafter, the present invention will be described in detail with reference to examples.
A positive electrode plate and a negative electrode plate for a sealed lead-acid battery that has been subjected to chemical conversion treatment; 1-No. 10 and Comparative Example No. 11-No. An electrode plate group was constructed by combining the laminated separators shown in FIG. 14, and a 12-V sealed lead-acid battery having a 5-hour capacity ratio of 6 Ah was produced.
In addition, the space volume of a positive electrode plate and a negative electrode plate used the thing of Table 1, respectively.

  The electrode plate group consists of four 2.0 mm-thick positive plates and five 1.3 mm-thick negative plates on the felt separator A, porous synthetic resin film B, and negative electrode plate in contact with the positive electrode plate. A laminated separator C having a laminated structure in which the felt-like separator C on the side in contact is positioned at the center of the porous synthetic resin film B and sandwiched between the felt-like separators A and C at a temperature of 120 ° C. and 20 kPa. A positive electrode plate was sandwiched in a diaper shape by a laminated separator produced by heat fusion, and a negative electrode plate was superimposed on the positive electrode plate to produce an alternating laminate. The produced electrode plate group is adjusted with a spacer so that the compression degree is 40-60 kPa and the total thickness of the felt separators A and B of the stacked separators is about 0.7 mm. did. In addition, No. of the present invention example. In No. 8, the same felt-shaped separator on the side in contact with the negative electrode plate was overlapped.

The felt separator includes glass fiber as a main component and 20% by mass of polyethylene fiber as a heat-sealing fiber. In Table 1, No. of the present invention example. The felt-like separator used in No. 6 does not contain heat-sealing fibers, so it was used without heat-sealing.
The porous synthetic resin film was made of polyethylene.

A sealed lead-acid battery was assembled by attaching a lid to the battery case into which the electrode plate group had been inserted by heat sealing. These sealed lead-acid batteries were injected with 50 cm ³ of dilute sulfuric acid having a specific gravity of 1.30, subjected to initial charge and a 5-hour rate capacity test, and confirmed that the 5-hour capacity rate was about 6 Ah.

  The produced sealed lead-acid battery was used as a test material, and the low temperature rapid discharge characteristics and short circuit resistance were measured. The results are shown in Table 2.

  For the low temperature rapid discharge characteristics, a fully charged specimen was held at −30 ° C. for 16 hours, then discharged at −30 ° C. with a current corresponding to 5 C, and the voltage after 10 seconds of discharge was measured. After that, the battery was fully charged again, and the 40 ° C light load life test specified in JIS D5301 was conducted for one week. After that, the fully charged specimen was held at -30 ° C for 16 hours, and the equivalent of 5C at -30 ° C. The battery was discharged with current, and the voltage after 10 seconds of discharge was measured.

The short circuit resistance is No. of the present invention example in Table 1. 1-No. 10 and Comparative Example No. 11-No. A test cell prepared by sandwiching 14 laminated separators between a positive electrode plate and a negative electrode plate and pressurizing at 50 kPa is immersed in a saturated lead sulfate aqueous solution and energized at a current density of 5 mA / cm ² , resulting in a potential difference of 0V. The time until was measured.

  Tables 1 and 2 show examples of the present invention. 1-No. As can be seen from FIG. 10, the sealed lead-acid battery according to the present invention in which the laminated separator is defined and the space volume of the positive electrode plate and the negative electrode plate is specified is excellent in low-temperature rapid discharge characteristics after the life test and is resistant to Short circuiting is also good.

  On the other hand, No. of the comparative example using the separator comprised only with the felt-like separator. No. 11, both low temperature rapid discharge characteristics and short circuit resistance are reduced, and a short circuit occurs particularly in a short time. Comparative Example No. 1 in which the space volume of the felt separator in contact with the positive electrode plate and the negative electrode plate was the same. In No. 12, the low temperature rapid discharge characteristics after the life test are deteriorated, and the short circuit resistance is also inferior. No. of the example of the present invention. No. 2 of the comparative example in which the laminated separator having the same structure as that of No. 2 is used but the space volume of the positive electrode plate and the negative electrode plate is the same. No. 13 and Comparative Example No. 1 in which the space volume of the negative electrode plate is larger than that of the positive electrode plate. In 14, the low-temperature rapid discharge characteristics are degraded.

Claims (4)

In a sealed lead-acid battery having a negative electrode plate, a separator, and an electrode plate group in which positive electrode plates are laminated, the separator has a felt-like shape in which a porous synthetic resin film is arranged in the center and glass fiber is a main component from both sides. A laminated separator having a laminated structure sandwiched between separators, wherein the spatial volume of the felt separator in contact with the positive electrode plate of the laminated separator is smaller than the spatial volume of the felt separator in contact with the negative electrode plate, and the positive electrode A sealed lead-acid battery, wherein the space volume of the plate is larger than the space volume of the negative electrode plate. 2. The sealed lead-acid battery according to claim 1, wherein two or more felt-like separators sandwiching the porous synthetic resin film from both sides are arranged on at least one side of the porous synthetic resin film. The sealed lead-acid battery according to claim 1 or 2, wherein the felt-like separator includes a heat-fusible synthetic fiber. The porous synthetic resin film is made of polyethylene or polypropylene, and has a pore diameter of 0.1 μm or less and a film thickness of 0.03 to 0.5 mm. The sealed lead-acid battery described in 1.