JP2008171701A - Lead acid storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead acid storage battery superior in reliability in which deformation of a strap and an electrode plate ear and resultant disconnection and short circuit are suppressed, even if deformation of the positive electrode plate and vibration of the battery are brought about. <P>SOLUTION: An insulation member 8 of a thermoplastic resin such as polyolefin system resin or the like is arranged at the lower part of a strap 5 which connects the ears of same polarity. This insulation member covers the whole face of the surface of the ears 6, 7 connected to the strap and a portion opposed to the lower face of the strap of a separator and an electrode plate having a different polarity from the strap. Then, a space part 9 in which the insulation member is not arranged is provided between the lower face of the strap and the electrode plate having the different polarity from the strap. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lead-acid battery.

With a long-term use of a lead-acid battery, a phenomenon occurs in which the positive electrode grid is oxidatively corroded and the positive electrode plate extends upward. For this reason, the upper end of the positive electrode plate and the negative electrode ear or the strap come into contact with each other, causing an internal short circuit and extending the life. As a method for preventing this, a method of inserting a comb-like resin molded body into the lower part of the negative strap is employed. Patent Document 1 discloses a configuration in which an electrically insulating material is fixedly disposed on a portion corresponding to a negative electrode strap of an electrode plate group.
JP 2003-197252 A

  Patent Document 1 discloses a configuration in which the positive electrode plate and the negative electrode plate are fixed to each other using an electrically strong thermosetting resin such as an epoxy resin. When the corrosion of the positive electrode plate is mild, the elongation of the positive electrode plate due to the corrosion is suppressed.

  However, when the corrosion of the positive electrode plate further progresses, the negative electrode plate ear fixed to the positive electrode plate with a high-strength epoxy resin is pushed upward along with the upward extension of the positive electrode plate. Furthermore, the strap that connects the ears will be pushed up. As a result, the strap of the negative electrode may be bent in an inverted V shape and disconnected. Epoxy resin is excellent in tensile yield strength and compressive yield strength, but when the deformation of the positive electrode plate proceeds and the deformation exceeds a certain value, the resin suddenly cracks and the fixing effect by the resin is greatly increased. In some cases, it was damaged.

  In addition, in lead storage batteries that are used in an environment subject to vibration, such as a lead storage battery for starting, especially for vehicles, stress due to vibration is concentrated at the connection between the strap and the ear, and the ear breaks at this part, The strap could be deformed.

  Furthermore, with liquid lead-acid batteries, the liquid level of the liquid lead-acid battery decreases when the liquid is reduced, and if the negative-electrode strap and ears are exposed, corrosion occurs in the straps and ears and this progresses. Lead to corrosion disconnection.

  The above-mentioned disconnection of the ears and deformation and disconnection of the strap not only reduce the capacity of the battery, but also cause a discharge spark inside the battery due to an internal short circuit due to the disconnection or deformation, and lead discharge battery There was a problem that the battery was damaged by igniting the hydrogen gas generated during charging.

  In order to solve the above-described problems, the present invention has a plurality of positive plates and negative plates that are alternately stacked via separators, and each of the positive plates and the negative plates has a current collecting ear. And an insulating member made of a thermoplastic resin such as a polyolefin resin is disposed below the strap, and the insulating member is connected to the strap. Covering the entire surface of the surface, a portion of the separator facing the lower surface of the strap, and a portion of the electrode plate having a polarity different from that of the strap, facing the lower surface of the strap, and the lower surface of the strap and the The lead storage battery which provided the space part in which the said insulating member is not arrange | positioned between the pole plate which has a different polarity from a strap is shown.

  In the present invention, more preferably, at least a portion of the lower surface of the strap adjacent to the base of the ear is covered with the insulating member.

  In the present invention, more preferably, at least one of the positive electrode plate and the negative electrode plate has an expanded electrode plate.

  According to the present invention, the short circuit between the electrode plate and the strap, the disconnection of the ear, the deformation of the strap, and the disconnection inside the lead storage battery are suppressed. Moreover, the battery damage by the discharge spark which generate | occur | produces by these disconnection can be suppressed, and it has the remarkable effect that the lead storage battery excellent in reliability can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG.1 and FIG.2 is a figure which shows the electrode group 1 used for the lead acid battery of this invention. The lead storage battery of the present invention is characterized by the structure of the electrode group 1, and the electrode group 1 is housed in a battery case and the battery is assembled by a known structure such as mounting a lid on the battery case. Thus, the lead storage battery of the present invention can be obtained. Therefore, the configuration other than the electrode plate group 1 will not be described in detail.

  The electrode plate group 1 of the lead storage battery of the present invention has a structure in which a plurality of positive electrode plates 2 and negative electrode plates 3 are laminated via separators 4. The positive electrode plate 2 and the negative electrode plate 3 are provided with a positive electrode ear 6 and a negative electrode ear 7 for current collection, respectively.

  The negative electrode ear 7 is connected by a negative electrode strap 5. The positive electrode ear 6 is connected by a positive electrode strap 10.

  As shown in FIG. 1, the lead storage battery of the present invention has an insulating member 8 disposed below the negative strap 5. As shown in FIG. 2, the insulating member 8 covers the entire surface 7 a of the negative electrode ear 7 connected to the negative electrode strap 5. Further, the insulating member 8 covers a portion corresponding to the lower surface 5 a of the negative electrode strap 5 of the positive electrode plate 2 and the separator 4.

  Further, in the present invention, the electrode plate having a polarity different from that of the negative electrode strap 5, that is, the space portion 9 in which the insulating member 8 is not disposed is provided between the positive electrode plate 2 and the lower surface 5 a of the negative electrode strap 5.

  In the present invention, a thermoplastic resin such as a polyolefin resin such as a polypropylene resin or a polyethylene resin is used as the insulating member 8. After the negative electrode strap 5 is formed, the insulating member 8 is formed by filling the lower part of the negative electrode strap 5 with a thermoplastic resin that is heated and has fluidity, and cooling and solidifying it. In this respect, a thermosetting resin such as an epoxy resin is not preferable in terms of productivity because it takes time to cure.

  There are also room temperature curing type epoxy resins that can be cured in a relatively short time. However, it is necessary to fill a space having a complicated three-dimensional shape, such as the lower part of the negative electrode strap 5, so that curing occurs during the filling operation. Since it progresses, it is not preferable. On the other hand, the thermoplastic resin is most preferable because it can control the fluidity of the resin depending on the temperature and is suitable for the purpose of filling a complex three-dimensional space as in the present invention.

  In the present invention, even when the positive electrode plate 2 is deformed due to corrosion and the insulating member 8 is pushed upward, the space portion 9 exists between the lower surface 5a of the negative electrode strap 5 and the positive electrode plate 2, and thus the negative electrode strap 2 The lower surface 5 a of 5 does not push up the positive electrode plate 2 via the insulating member 8.

  On the other hand, when the space 9 is not provided, the positive electrode plate 2 is stretched by pushing the negative strap 5 upward from below through the insulating member 8 so that the negative strap 5 is deformed into an inverted V shape or is broken. Occurs.

  Furthermore, the insulating member 8 covers the surface 7a of the negative electrode ear 7 to suppress disconnection of the negative electrode ear 7 when vibration is applied to the battery. When there is a portion that is not covered with the insulating member 14 on the surface 7a of the negative electrode ear 7 as in the conventional electrode plate group 13 shown in FIG. 3, the portion that is not covered with the insulating member 14 of the negative electrode ear 7 is caused by vibration. It will deform intensively and eventually break. As shown in FIG. 2, in the present invention, since the insulating member 8 is present on the entire surface 7a, such deformation of the negative electrode ear 7 and disconnection due to this can be suppressed.

  Moreover, since the insulating member 8 is disposed between the positive electrode plate 2 and the negative electrode strap 5, a short circuit between the positive electrode plate 2 and the negative electrode strap 5 can be suppressed. In order to further improve the vibration resistance of the negative electrode ear 7, the insulating member 8 that covers the surface 7a of the negative electrode ear 7 is a negative electrode adjacent to the surface 7a, as in the electrode plate group 1 'shown in FIG. It is preferable to cover the lower surface 5 a of the strap 5.

  2 and 4 show an example in which the space portion 9 is arranged in contact with the lower surface 5a of the negative electrode strap 5, the space portion 9 is made of the insulating member 8 as in the electrode plate group 1 ″ shown in FIG. 2, 4, and 5, the insulating member 8 is deformed by receiving stress in the direction of the negative strap 5 due to the corrosion deformation of the positive electrode plate 2. By accommodating the deformed portion of the member 8 in the space 9, the stress on the insulating member 8 is relieved by the deformation of the insulating member 8. As a result, even if the positive electrode plate 2 is deformed, the negative strap 5 deformation is suppressed.

  Furthermore, in the present invention, since the surface 7a of the negative electrode ear 7 is entirely covered with the insulating member 8, the disconnection due to corrosion of the negative electrode ear 7 that is likely to occur when the negative electrode ear 7 is exposed from the electrolyte is suppressed. You can also.

  According to the present invention, it is possible to suppress disconnection of the negative electrode ear 7 and the negative electrode strap 5 or a short circuit between the negative electrode strap 5 and the positive electrode plate 2 that occurs when the positive electrode plate 2 is corroded or when vibration is applied to the battery. Can do.

  When a disconnection or a short circuit occurs at such a portion exposed from the electrolytic solution surface, an electric spark is generated, which may ignite hydrogen gas accumulated in the battery and may damage the battery. According to the present invention, disconnection of electrode plate ears and straps and internal short-circuiting, which can be a factor of rupture, are suppressed, and as a result, it is possible to prevent the occurrence of electrical sparks that cause battery damage.

  In the present embodiment, the example in which the insulating member 8 is disposed below the negative strap 5 has been described. The positive electrode plate 2 is an electrode plate that is elongated due to corrosion deformation when the lead storage battery is charged and discharged. Moreover, the negative electrode ear 7 is subject to corrosion from exposure from the electrolyte surface, and disconnection is likely to occur. Therefore, it is necessary to dispose the insulating member 8 below the negative electrode strap 5 for the purpose of preventing these phenomena.

  However, in order to prevent deformation of the electrode plate ear, breakage, and internal short circuit between the strap and the electrode plate when vibration is applied to the battery, in addition to the arrangement of the insulating member 8 below the negative electrode strap 5, FIG. As shown in FIG. 5, it is more preferable to dispose the insulating member 8 ′ below the positive strap 10. The positive electrode side insulating member 8 ′ can be made of the same material as the negative electrode side insulating member 8.

  The arrangement of the positive electrode strap 10 at the lower portion of the insulating member 8 ′ has the same configuration as that of the insulating member 8 arranged at the lower portion of the negative electrode strap 5. That is, the insulating member 8 ′ covers the surface corresponding to the surface of the positive electrode ear 6, the lower portion of the negative electrode plate 3 and the positive electrode strap 10 of the separator 4.

  Furthermore, a space portion 9 ′ can be provided between the negative electrode plate 3 and the positive electrode strap 10. In addition, since the negative electrode plate 3 hardly deforms due to charging / discharging, the space 9 ′ is not essential only on the positive electrode strap 10 side.

  As shown in FIGS. 2, 4 and 5, in the example where the negative electrode plate 3 is located at the end of the electrode plate group 1, 1 ′, 1 ″, the negative electrode ear 7 of the negative electrode plate 3 located at this end. The surface 7a on the outer side of the electrode plate group 1, 1 ', 1 "does not necessarily need to be covered with the insulating member 8, and the effect of the present invention can be obtained without being covered.

  When using an expandable electrode plate having an expanded lattice (not shown) as the positive electrode plate 2 and the negative electrode plate 3, compared to a cast electrode plate having a cast lattice in which all frame frames are arranged around the lattice. Electrode plate deformation due to vibration is likely to occur. Therefore, the present invention is suitable for a lead storage battery using an expanded electrode plate for at least one of a positive electrode and a negative electrode.

  As shown below, lead-acid batteries (hereinafter referred to as batteries) according to the present invention and comparative examples were prepared, and life evaluation and vibration resistance performance evaluation were performed. In each of the batteries of the present invention and the comparative example, a positive electrode plate, a negative electrode plate, and a separator, which will be described later, were used, and an electrode plate group composed of five positive electrode plates and six negative electrode plates per cell was prepared. The positive and negative straps were made of Pb-2.5 mass% Sb alloy.

  The positive electrode plate is formed by expanding a lead alloy sheet made of a Pb-alloy of Pb-0.07 mass% Ca-1.3 mass% Sn to form a lattice, and lead powder (metal lead, lead monoxide and After filling a predetermined amount of paste kneaded with water and dilute sulfuric acid, a positive electrode plate was produced by aging and drying.

  For the negative electrode plate, a Pb-0.07 mass% Ca-0.25 mass% Sn alloy sheet was expanded in the same manner as the positive electrode, and expanded to lead powder (a mixed powder of metal lead and lead monoxide) (barium sulfate). And lignin) and carbon were added, and a negative electrode active material paste prepared by kneading with water and dilute sulfuric acid was filled in a lattice and aged and dried to obtain a negative electrode plate.

  As a separator, a microporous polyethylene sheet having a thickness of 0.3 mm was folded in a U shape, and both sides were heat-sealed to prepare a bag-like separator having only an upper portion opened. The microporous polyethylene sheet used had micropores with a maximum pore diameter of 10 μm. A positive electrode plate was accommodated in this bag-like separator.

  Various insulative synthetic resins are arranged in various forms on the lower surface of the negative electrode strap of the electrode plate group, and using these electrode plate groups, a battery according to the present invention and a comparative example (55D23 type start lead in JIS D5301). A storage battery (nominal voltage 12V, rated capacity 48Ah) was prepared.

(Battery A1 of the present invention example)
The battery A1 of the present invention uses the electrode plate group 1 shown in FIG. The insulating member 8 disposed below the negative electrode strap 5 covers the entire surface 7 a of the negative electrode ear 7, and the portions corresponding to the lower side of the negative electrode strap 5 of the positive electrode plate 2 and the separator 4. A space portion 9 is provided in contact with the lower surface 5a of the negative electrode strap 5 in which the insulating member 8 is not disposed. However, the insulating member 8 is not disposed on the surface 7 a located outside the electrode plate group 1 among the negative electrode ears 7 of the negative electrode plate 3 at both ends of the electrode plate group 1.

  The insulating member 8 in the battery A1 is a polypropylene resin and has physical properties of a tensile yield stress of 30 Mpa and a compressive yield stress of 60 MPa.

(Battery A2 of the present invention example)
The battery A2 of the present invention uses the electrode plate group 1 'shown in FIG. That is, the insulating member 8 covers a part of the lower surface 5 a of the negative electrode strap 5 in the vicinity of the negative electrode ear 7. Other configurations are the same as the battery A1 of the present invention. Of the negative electrode ears 7 of the negative electrode plate 3 at both ends of the electrode plate group 1 ′, the insulating member 8 is not disposed on the surface 7 a located outside the electrode plate group 1 ′.

(Battery A3 of the present invention example)
The battery A3 of the present invention uses the electrode plate group 1 ″ shown in FIG. 5. That is, the insulating member 8 covers the lower surface 5a of the negative electrode strap 5, and the insulating member 8 includes the space 9 therein. The other configuration is the same as that of the battery A1 of the example of the present invention. Of the negative electrode ears 7 of the negative electrode plate 3 at both ends of the electrode plate group 1 ″, the structure is located outside the electrode plate group 1 ″. The insulating member 8 is not disposed on the surface 7a.

(Battery B1 of the present invention example)
In the battery B1 of the present invention example, the material of the insulating member 8 in the battery A1 of the present invention example is a polyethylene resin having physical properties of a tensile yield stress of 30 Mpa and a compressive yield stress of 25 MPa.

(Battery B2 of the present invention example)
In the battery B2 of the present invention example, the material of the insulating member 8 in the battery A2 of the present invention example is a polyethylene resin having the same physical properties as those used in the battery B1.

(Battery B3 of the present invention example)
In the battery B3 of the present invention example, the polyethylene resin having the same physical properties as those used in the battery B1 is used as the material of the insulating member 8 in the battery A3 of the present invention example.

(Comparative battery A4)
As shown in FIG. 7, the battery A <b> 4 of the comparative example uses the electrode plate group 11 in which the entire space located below the negative electrode strap 5 is filled with the insulating member 12. The insulating member 12 is a polypropylene resin having the same physical properties as the insulating member 8 used in the battery A1.

(Comparative battery B4)
In the battery B4 of the comparative example, the insulating member 12 in the battery A4 of the comparative example is a polyethylene resin having the same physical properties as the insulating member 8 used in the battery B1.

(Comparative battery A5)
As shown in FIG. 3, the battery A5 of the comparative example insulates the base portion of the negative electrode ear 7 with the negative electrode plate 3 below the negative electrode strap 5 and the portion located below the separator 4 and the negative electrode strap 5 of the positive electrode plate 2. The electrode group 13 covered with the member 14 is used. The insulating member 14 does not cover a portion of the negative electrode ear 7 adjacent to the negative electrode strap 5. The insulating member 14 is a polypropylene resin having the same physical properties as those used in the battery A1.

(Comparative battery C1)
The battery C1 of the comparative example is the same as the battery A1 of the present invention, in which the material of the insulating member 8 is a thermosetting epoxy resin having a tensile yield stress of 50 MPa and a compressive yield stress of 100 MPa.

(Comparative battery C2)
The battery C2 of the comparative example is the same as the battery A2 of the present invention example, in which the insulating member 8 is made of the same epoxy resin as that used for the battery C1.

(Comparative battery C3)
The battery C3 of the comparative example is the same as the battery A3 of the example of the present invention in which the insulating member 8 is made of the same epoxy resin as that used for the battery C1.

(Comparative battery C4)
The battery C4 of the comparative example is the same as the battery A4 of the comparative example, except that the insulating member 12 is made of the same epoxy resin as that used for the battery C1.

(Comparative battery C5)
The battery C5 of the comparative example is the same epoxy resin as that used for the battery C1 in the battery A5 of the comparative example.

(Comparative battery D)
As shown in FIG. 8, the battery D of the comparative example is a battery that includes the positive electrode plate 2, the negative electrode plate 3, the separator 4, and the negative electrode strap 5, and has an electrode plate group 15 that does not have an insulating member.

  The above-described battery of the present invention and the battery of the comparative example were subjected to a life test and a vibration test under the following conditions, and the state of the electrode plate ear and the strap (presence of deformation, disconnection, short circuit, etc.) was confirmed.

(Life test)
In the life test, each battery is charged at a constant voltage of 13.8 V for 144 hours (6 days), and then left for 24 hours (1 day), and then a confirmation discharge is performed at 300 A for 5 seconds. Repeat the discharge cycle. When the end-of-discharge voltage at the time of the confirming discharge has dropped to 7.2V, the life ends. The life test was performed in a gas phase atmosphere at 75 ° C. In addition, during the life test, the electrolyte level decreased, but each battery was not refilled at all.

(Vibration test)
In the vibration test, each battery (test number n = 3) was subjected to vibration for 2 hours in the left-right direction (perpendicular to the internal electrode plate surface) at a frequency of 30 Hz and an acceleration of 3G. In addition, after vibration, the battery was disassembled and the internal state was confirmed. For batteries with no abnormality inside the battery, three batteries were added, acceleration was increased to 5G, and a vibration test was performed. The vibration test of acceleration 5G was made by changing only the acceleration, and the vibration frequency and vibration time were the same as the vibration test of acceleration 3G at 30 Hz and 2 hours, respectively.

  Table 1 shows the number of life cycles in the above life test and the observation results of the state of the electrode plate ear and the strap after the life test.

  From the results shown in Table 1, the batteries A1 to A3, the batteries B1 to B3 of the example of the present invention, and the batteries A5 and C5 of the comparative example are not seen from the negative electrode strap, the deformation of the negative electrode ear, and the disconnection. There is no short circuit. As a result, the life cycle number was as good as 16 cycles. Although the positive electrode plate extended upward, no short circuit with the negative electrode strap was observed. Further, the upward deformation of the positive electrode plate was absorbed in the space 9 provided close to or including the insulating member 8.

  On the other hand, with respect to the battery A4 of the comparative example, the negative electrode strap was deformed into an inverted V shape by the expansion deformation of the positive electrode plate pushing up the negative electrode strap through the insulating member. Further, along with the deformation of the negative electrode strap, tensile stress was generated in the negative electrode ear, and the negative electrode ear was disconnected at the joint base with the negative electrode strap, and the life was significantly shorter than that of the battery of the present invention example.

  Regarding the batteries C1 to C4 using an epoxy resin as an insulating member, although upward deformation of the positive electrode plate was suppressed, a crack penetrating the insulating member vertically occurred due to the stress. As a result of the cracks being generated, the gap between the negative electrode ears 7 was expanded, and as a result, the negative electrode strap 5 was deformed into a U shape, causing a disconnection in a part of the negative electrode ears, and the batteries C1 to C4 had a short life.

  Such a phenomenon is that the compressive yield stress of the epoxy resin used in this example is 100 Mpa, which is very high compared to the values of the polypropylene resin and polyethylene resin (60 MPa, 25 MPa) used in other examples. It can be inferred that there is something. From this, it is considered that a range not exceeding 50 MPa is preferable as the compressive yield stress of the insulating member.

  As a result of the positive electrode plate extending upward, the battery D not using an insulating member was short-circuited with the negative electrode strap and had a short life.

  Next, Table 2 shows the vibration test results of the respective batteries.

  From the results shown in Table 2, with respect to the battery A5 and the battery C5 of the comparative example, stress during vibration was concentrated on a portion of the negative electrode ear that was not covered with the insulating member, and this portion was bent. Some negative electrode ears were disconnected.

  Moreover, about the battery D which does not have an insulating member, the positive electrode plate floated upwards and was short-circuited with the negative electrode strap.

  Regarding the batteries A1 to A4, the batteries B1 to B3, and the batteries C1 to C4, no abnormality was found in the negative electrode strap or the negative electrode ear at the acceleration 3G. About these batteries, the vibration test which increased acceleration to 5G using the new battery was additionally done. As a result, for battery A1 and battery B2, some deformation of the negative electrode ear was observed, but no disconnection or short circuit occurred, and there was no practical problem. On the other hand, regarding the batteries A2 to A4, the batteries B2 to B3, and the batteries C1 to C4, no abnormality was recognized even at the acceleration 5G.

  When the life test and vibration test results are combined, the batteries A2 to A4 and the batteries B2 to B3 of the example of the present invention are compared to the batteries of the other comparative examples. It can be understood that the deformation, disconnection or short circuit of the plate ear is remarkably suppressed.

  Regarding the battery A1 and the battery B2 of the present invention, a slight deformation of the negative electrode ear was observed in a region where the acceleration of vibration was high, but the deformation did not affect the battery life, and there was no practical problem. It was a thing.

  However, it is preferable to use the battery A2 to A3 or the battery B2 to B3 according to the example of the present invention particularly for agricultural machinery and construction machinery that requires vibration resistance.

  From the above, according to the present invention, it is possible to suppress deformation of the strap and electrode plate ears and disconnection and short circuit due to deformation of the positive electrode plate and vibration of the battery. In addition, since it is possible to prevent the occurrence of electrical spark due to disconnection or short circuit, the remarkable effect of suppressing the ignition of hydrogen gas staying in the battery of such an electrical spark and the resulting battery damage. Can be obtained.

  In this embodiment, the case where the insulating member is disposed only at the lower part of the negative strap has been described. However, the effect of the present invention can be obtained even when the insulating member is disposed at the lower part of the positive strap in addition to the lower part of the negative strap. Is clear. In particular, with respect to the battery A1 and the battery B1 of the present invention, as shown in FIG. 5, the insulating member 8 provided under the negative strap 5 is similarly provided as the insulating member 8 'under the positive strap 10 to accelerate the battery. It was possible to prevent the deformation of the negative electrode ear, which was slightly generated in the vibration test at 5G.

  Therefore, for the purpose of further improving the vibration resistance, it is more preferable to provide an insulating member 8 ′ below the positive strap 10.

  The lead storage battery of the present invention has a remarkable effect that it can suppress deformation, disconnection, or short-circuit of the electrode plate ear or the strap due to the extension of the positive electrode plate or battery vibration. It is useful for lead storage batteries for various purposes.

The figure which shows the outline of the electrode group of the lead acid battery of this invention The figure which shows the cross section of the electrode group of the lead acid battery of this invention The figure which shows the cross section of the electrode group of the conventional lead acid battery The figure which shows the cross section of the electrode plate group of the other lead acid battery of this invention. The figure which shows the cross section of the electrode plate group of the other lead acid battery of this invention. The figure which shows the other cross section of the electrode group of the lead acid battery of this invention The figure which shows the cross section of the electrode group of the lead acid battery of a comparative example The figure which shows the cross section of the electrode group of the lead acid battery of a comparative example

Explanation of symbols

1, 1 ′, 1 ″ electrode plate group 2 positive electrode plate 3 negative electrode plate 4 separator 5 negative electrode strap 5a bottom surface 6 positive electrode ear 7 negative electrode ear 7a surface 8, 8 ′ insulating member 9, 9 ′ space 10 positive electrode strap 11 electrode plate group 12 Insulating member 13 Electrode plate group 14 Insulating member 15 Electrode plate group

Claims (3)

Each has a plurality of positive plates and negative plates stacked alternately via separators, each of the positive plates and the negative plates having current collecting ears, and straps for connecting the ears of the same polarity. An insulating member made of a thermoplastic resin such as a polyolefin-based resin is disposed below the strap, and the insulating member covers the entire surface of the ear surface connected to the strap, the separator, and the strap. A portion facing the lower surface and a portion of the electrode plate having a polarity different from that of the strap, covering a portion facing the lower surface of the strap, and between the lower surface of the strap and the electrode plate having a polarity different from that of the strap, The lead acid battery which provided the space part in which the said insulating member is not arrange | positioned. The lead acid battery according to claim 1, wherein at least a portion of the lower surface of the strap adjacent to the base of the ear is covered with the insulating member. The lead acid battery according to claim 1 or 2, wherein at least one of the positive electrode plate and the negative electrode plate is an expandable electrode plate.

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