JP2005285638A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery in which an internal short-circuit can be prevented. <P>SOLUTION: A first electrode plate 24 of the battery that pinches a separator 28 between a second electrode plate 26 and the electrode plate is wound up in a spiral form. The first electrode plate 24 has an conductive plate board 42 of a porous structure in a belt form, and the conductive plate board 42 is filled up with an active material. The conductive plate board 42 has an area of a non-filled part 44 at the edge of one side that is not filled with the active material, and a metal thin sheet 48 is fixed to the non-filled part 44 from one face side of the conductive plate board 42. The non-filled part 44 and the metal sheet 48 are pinched by two protection members 50, 52 from both sides of the conductive plate board 42, and in the protection members 50, 52, the protection member 50 on the side of the non-filled part 44 is thicker than the protection member 52 on the side of the metal sheet 48. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery.

In recent years, alkaline storage batteries such as batteries, particularly nickel metal hydride secondary batteries, have been used as power sources for electric tools, assist bicycles, electric vehicles, etc., and further increases in capacity, output, or improvement in high rate discharge characteristics are desired. It is rare.
For example, Patent Document 1 discloses a battery excellent in high rate discharge characteristics. In this battery, a current collecting plate is provided on one end side of a spiral electrode group including a first electrode, and this current collecting plate is welded to the first electrode. More specifically, the first electrode includes a substrate made of a metal porous body, and this substrate is formed with an active material filling portion and a strip-shaped connecting portion to be welded to the current collector plate. The portion extends along one side edge of the first electrode as viewed in the winding direction of the electrode group. And in the 1st electrode shown by FIG. 9 of patent document 1, the current collector plate and the metal thin plate which should be welded are piled up and welded to one side of a strip | belt-shaped connection part, and this metal thin plate is welded. A protective tape having the same thickness is attached to the outer surface of the belt and the other surface of the belt-like connecting portion.
JP 2000-21435 A

  By the way, since the positive electrode plate which is the first electrode described above has protective tapes on both sides thereof, when the positive electrode plate is wound together with the separator and the negative electrode plate to form an electrode group, The thickness of the positive electrode plate is shifted due to the thickness, and the side edge of the positive electrode plate, that is, the metal thin plate is not flush with one end surface side of the electrode group. When the current collector plate is pressed and welded to one end face of such an electrode group, the protruding portion of the thin metal plate or the strip-like connecting portion is bent by the current collector plate, causing an internal short circuit. For this reason, the one where the thickness of these masking tapes is thin is preferable.

However, the skeleton forming the porous metal body is easily broken, and when the positive electrode plate is wound, the skeleton is locally broken, and a part of the broken skeleton protrudes from the belt-like connecting portion. For this reason, when the thickness of these protective tapes is thin, a part of the fractured skeleton breaks through the protective tape and the separator on the side of the belt-like connecting portion, and also causes an internal short circuit.
The present invention has been made based on the above-described circumstances and provides a battery in which an internal short circuit is prevented.

  In order to achieve the above object, according to the present invention, the first electrode plate and the second electrode plate are provided with an electrode group in which a separator is sandwiched and wound in a spiral shape. In a battery including a strip-shaped conductive substrate having a porous structure of a porous plate and an active material filled in the conductive substrate, the conductive substrate of the first electrode plate is a winding of the electrode group. A non-filled portion not filled with the active material is provided on one side edge along the direction, and the thin metal plate superimposed on the non-filled portion, and the non-filled portion and the thin metal plate are sandwiched from both sides of the conductive substrate. And a protective member on the non-filled portion side of the protective member is thicker than the protective member on the thin metal plate side (Claim 1). .

According to this configuration, the thickness of the protective member on the metal thin plate side is made thinner than the protective member on the non-filling portion side, so that the first electrode plate, the second electrode plate, and the separator are swirled by the reduced thickness. When winding in a shape, it is possible to suppress winding deviation of the first electrode plate. On the other hand, since the protective member on the non-filled portion side is thicker than the protective member on the conductive thin plate side, the skeleton of the conductive substrate is locally broken when the first electrode plate is wound, and a part of the skeleton is Even if it protrudes from the non-filling portion, it does not penetrate the protective tape and the separator.
As a preferred embodiment, the protective member is made of an adhesive tape (Claim 2).

  As described above, according to the batteries of claims 1 and 2, while preventing the winding displacement at the first electrode plate, the skeleton of the broken conductive substrate may penetrate the protective tape and the separator. No internal short circuit can be prevented. For this reason, this battery is of high quality and can be manufactured with high productivity.

Hereinafter, a nickel-hydrogen secondary battery will be described as a battery according to an embodiment of the present invention.
This battery is an AA size cylindrical battery, and as shown in FIG. 1, includes an outer can 10 having a bottomed cylindrical shape with an open upper end, and the bottom wall of the outer can 10 has a conductive negative electrode. Functions as a terminal. In the opening of the outer can 10, a disc-shaped cover plate 14 having conductivity is arranged via a ring-shaped insulating packing 12, and the cover plate 14 and the insulating packing 12 caulk the opening edge of the outer can 10. It is being fixed to the opening edge of the armored can 10 by processing.

The cover plate 14 has a gas vent hole 16 in the center, and a rubber valve element 18 is disposed on the outer surface of the cover plate 14 so as to close the gas vent hole 16. Further, a flanged cylindrical positive electrode terminal 20 covering the valve element 18 is fixed on the outer surface of the cover plate 14, and the positive electrode terminal 20 presses the valve element 18 against the cover plate 14. The body 18 and the positive terminal 20 form a safety valve.
The outer can 10 accommodates a substantially cylindrical electrode group 22. The electrode group 22 includes a belt-like positive electrode plate 24, a negative electrode plate 26, and a separator 28. The separator 28 is sandwiched between the positive electrode plate 24 and the negative electrode plate 26 wound in a spiral shape.

A predetermined amount of an alkaline electrolyte (not shown) is injected into the outer can 10, and charging / discharging is performed between the positive electrode plate 24 and the negative electrode plate 26 through the alkaline electrolyte contained in the separator 28. The reaction proceeds.
Further, in the outer can 10, a circular metal negative electrode current collector plate 30 is disposed between the bottom wall and the electrode group 22, and the negative electrode plate 26 is disposed via the negative electrode current collector plate 30. The outer can 10 is electrically connected. More specifically, the negative electrode plate 26 includes a negative electrode substrate 32 made of, for example, punching metal, and a negative electrode active material layer 34 containing a hydrogen storage alloy is held on both surfaces of the negative electrode substrate 32. The negative electrode substrate 32 is provided with a connecting portion 36 that protrudes from the negative electrode active material layer 34 toward the negative electrode current collector plate 30, and the connecting portion 36 is welded to the negative electrode current collector plate 30.

Further, in the outer can 10, a circular metal positive electrode current collector plate 38 is also disposed between the electrode group 22 and the lid plate 14. The positive electrode current collector plate 38 is integrally formed with a strip-like lead portion 40, and the leading end of the lead portion 40 is welded to the cover plate 14. The positive electrode plate 24 is electrically connected to the positive electrode terminal 20.
More specifically, the positive electrode plate 24 is a non-sintered electrode and includes a conductive positive electrode substrate 42 having a strip shape as shown in FIG. The positive electrode substrate 42 has a porous structure and includes innumerable holes formed by a skeleton having a three-dimensional network structure. The voids of the positive electrode substrate 42 are filled with nickel hydroxide particles as a positive electrode active material except for the side edge portion 44 positioned on the positive electrode current collector plate 38 side in the winding direction of the electrode group 22.

  The side edge portion 44 of the positive electrode substrate 42 is compressed from both sides in the thickness direction and is thinner than a portion (main body portion 46) filled with the positive electrode active material, and a strip-shaped metal thin plate 48 is welded to one surface thereof. ing. The thin metal plate 48 is wider than the side edge portion 44 and protrudes from the side edge portion 44 when viewed in the width direction of the positive electrode plate 24, while its thickness matches the step between the side edge portion 44 and the main body portion 46. The main body 46 is substantially flush with the main body 46.

Protective tapes 50 and 52 are bonded to both surfaces of the positive electrode plate 24 so as to sandwich the side edge portion 44 and the metal thin plate 48 therebetween, and these protective tapes 50 and 52 are arranged in the longitudinal direction (winding direction) of the positive electrode plate 24. While extending over the entire region, the portion of the main body 46 adjacent to the side edge 44 across the step is also sandwiched.
The protective tapes 50 and 52 are made of, for example, an adhesive tape made of polypropylene and polyethylene. The protective tape 50 on the side edge 44 side has a thickness of, for example, 60 to 100 μm, while the protective tape 52 on the metal thin plate 48 side. Has a thickness of, for example, 20 to 50 μm. Therefore, the protective tape 50 on the side edge side is thicker than the protective tape 52 on the metal thin plate 48 side.

  FIG. 3 schematically shows an enlarged connection region between the positive electrode plate 24 and the positive electrode current collector plate 38 described above. In the electrode group 22, the positive electrode plate 24 is wound so that the thin metal plate 48 is on the outer side, and the protective tape 50 is positioned on the radially inner side and the protective tape 52 is positioned on the radially outer side. Further, when viewed in the axial direction of the electrode group 22, the side edge portion 44, the metal thin plate 48, and the protective tapes 50 and 52 of the positive electrode plate 24 protrude from the corresponding side edge portion 54 of the negative electrode plate 26. A thin metal plate 48 is welded to the plate 38. Therefore, the positive electrode plate 24 is electrically connected to the positive electrode terminal 20 through the metal thin plate 48.

The side edge portions 54 and 54 of the negative electrode plate 26 protrude from the main body portion 46 of the positive electrode plate 24 in the axial direction of the electrode group 22, and the positive electrode plate 24 is interposed via the separator 28 and the protective tapes 50 and 52. The side edge portion 44 and a part of the metal thin plate 48 are sandwiched.
The battery described above is good because the positive electrode plate 24 and the negative electrode plate 26 are electrically connected to the positive electrode terminal 24 and the negative electrode terminal (the outer can 10) via the positive electrode current collector plate 38 and the negative electrode current collector plate 30. High rate discharge characteristics.

  On the other hand, in the battery described above, when the positive electrode current collector plate 38 is pressed against the metal thin plate 48 and welded, the positive electrode plate 24 is bent near the step between the side edge portion 44 and the main body portion 46 due to stress concentration. However, since the vicinity of the step is covered with the protective tapes 50 and 52, the positive electrode plate 24 does not penetrate the separator 28 and contact the negative electrode plate 26. For this reason, in this battery, an internal short circuit between the positive electrode plate 24 and the negative electrode plate 26 is prevented.

  In the battery described above, since the thickness of the protective tape 52 is made thinner than that of the protective tape 50, the surface of the positive electrode plate 24 on the metal thin plate 48 side can be made even a little flat. When winding the positive electrode plate 24 and the negative electrode plate 26, the winding deviation of the positive electrode plate 24 can be suppressed. For this reason, since the side edge of the metal thin plate 48 is flush with the end face of the electrode group 22, when the positive electrode current collector plate 38 is pressed against the metal thin plate 48 for welding, the positive electrode plate 24 is bent near the step. Bending is suppressed. As a result, an internal short circuit can be further prevented.

  Furthermore, in the battery described above, the internal tape can be further prevented by making the protective tape 50 thicker than the protective tape 52. More specifically, when the positive electrode plate 24 and the negative electrode plate 26 are wound via the separator 28, the skeleton of the positive electrode substrate 24 is locally broken, but the side edge portion 44 is not filled with the positive electrode active material. Therefore, a part of the fractured skeleton is likely to protrude from the side edge portion 44. Therefore, in this battery, by thickening the protective tape 50 directly attached to the side edge portion 44, even if a part of the fractured skeleton protrudes from the side edge portion 44, it does not penetrate the protective tape 52 and the separator 28. The protective tape 52 and the separator 28 prevent a part of the fractured skeleton from coming into contact with the negative electrode plate 26.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the type of battery is not limited to a nickel-hydrogen secondary battery, but a nickel-cadmium secondary battery, lithium ion A secondary battery etc. may be sufficient, and also a primary battery may be sufficient.
In the above-described embodiment, the side edge portion 44 of the positive electrode substrate 42 is not filled with the positive electrode active material over the entire longitudinal direction, but a portion of the side edge portion 44 is filled with the positive electrode active material. May be. In this case, only the remaining portion of the side edge portion 44 is compressed, and the thin metal plate 48 may be welded to the compressed portion.

  Further, in the above-described embodiment, although the adhesive tape is used for the protective tapes 50 and 52, a heat welding tape may be used. However, the pressure-sensitive adhesive tape is preferable because its thickness can be easily adjusted and a welding step is not required when adhering to the side edge portion 44 or the metal thin plate 48. In addition, a protective tape made of polyolefin resin such as polypropylene and polyethylene has excellent alkali resistance and is suitable for an alkaline battery.

In the above-described embodiment, the outer can 10 is a negative electrode terminal, but the outer can 10 may be a positive electrode terminal. That is, the electrode group 22 may be accommodated in the outer can 10 such that the side edge portion 44 of the positive electrode plate 24 protrudes toward the bottom wall of the outer can 10.
In the above-described embodiment, the metal thin plate 48 protrudes from the side edge portion 44. However, the side edge portion and the conductive thin plate are flush with each other at the end face of the electrode group, and both the side edge portion and the conductive thin plate are provided. May be welded to the positive electrode current collector plate 38.

In the above-described embodiment, a metal porous body may be used as the negative electrode substrate of the negative electrode plate 26. In this case, similarly to the positive electrode plate 24, an unfilled portion is formed in the negative electrode substrate, and this non-filling is performed. A metal thin plate may be fixed to the portion, and a protective tape may be bonded so as to sandwich the non-filled portion and the metal thin plate.
In the above-described embodiment, the shape of the electrode group 22 is substantially cylindrical. However, the end face shape of the electrode group may be elliptical by pressing and deforming from both sides in the radial direction.

In the above-described embodiment, when the electrode group 22 is manufactured, the number of turns of the positive electrode plate 24 is not particularly limited, but is preferably in the range of 5 or less. This is because as the number of windings increases, it becomes difficult to suppress winding deviation. On the other hand, when the electrode group 22 is manufactured, the positive electrode plate 24 may be wound so that the metal thin plate 48 is positioned radially inside the electrode group with respect to the conductive substrate.
Further, in the above-described embodiment, the metal thin plate 48 is fixed to the side edge portion 44 by welding, but may be fixed using a conductive adhesive.

Example 1, Comparative Examples 1 and 2
1. Production of Battery (1) Production of Positive Electrode A sponge-like organic porous body, which is an open-cell polyurethane foam, was subjected to a conductive treatment, and then immersed in a plating solution in an electrolytic bath and plated with nickel. The plated organic porous body was roasted at a temperature of 750 ° C. for a predetermined time to remove the resin component of the organic porous body, and further sintered in a reducing atmosphere to obtain a metallic porous body made of nickel. The obtained metal porous body had a basis weight of about 600 g / m ² , a porosity of 95%, and a thickness of about 2.0 mm.

  On the other hand, 10 parts by weight of cobalt powder and 3 parts by weight of zinc oxide powder were added to 90 parts by weight of nickel hydroxide powder containing 2.5% by weight of zinc and 1% by weight of cobalt as a coprecipitation component. The whole was mixed, 50 parts by mass of an aqueous hydroxypropylcellulose solution (solid content: 0.2% by weight) was added to the mixture, and the whole was kneaded to obtain a paste-like positive electrode active material slurry.

  The obtained positive electrode active material slurry was filled in a metal porous body. The filling amount was adjusted so that the active material density after rolling was about 2.91 g / cc-void. After drying the active material slurry, the metal porous body was roll-rolled so as to have a thickness of about 0.70 mm. And the rolled metal porous body was cut | disconnected in strip shape, and the active material of the one side edge part was removed by ultrasonic peeling. Then, this side edge was roll-rolled again to a thickness of about 0.5 mm.

  Thereafter, a nickel ribbon having a thickness of 0.1 mm and a width of 3 mm was connected to one surface of the side edge portion by resistance electric welding, and the protective tape (Nichiban Co., Ltd.) having the thickness shown in Table 1 was attached to the nickel ribbon and the side edge portion. A positive electrode plate was made by bonding a polypropylene adhesive tape manufactured by company. However, no protective tape was bonded to the positive electrode plate of Comparative Example 2.

(2) Battery assembly The positive electrode plate produced as described above and the negative electrode plate containing a hydrogen storage alloy were wound through a separator made of polypropylene nonwoven fabric to obtain a spiral electrode group. After welding the positive electrode current collector plate and the negative electrode current collector plate to both ends of the spiral electrode group, the electrode group is inserted into the outer can, and the negative electrode current collector plate is spot welded to the bottom wall of the outer can and the positive electrode current collector. The lead portion of the plate was welded to the lid plate. Thereafter, an electrolytic solution composed of a 7.5N potassium hydroxide aqueous solution containing lithium hydroxide and sodium hydroxide was poured into the outer can. Then, the opening edge is caulked in a state where the cover plate is disposed in the opening of the outer can through the insulating packing, and as Example 1, Comparative Examples 1 and 2, a cylindrical nickel hydrogen secondary having a nominal capacity of 1200 mAh 1000 batteries were manufactured.

2. Short-circuit evaluation test The inter-terminal voltage of the batteries of the obtained examples and comparative examples was measured, and when this inter-terminal voltage was 0.1 V or less, it was determined that an internal short circuit occurred, and an internal short circuit occurred among 1000 pieces. The number of batteries was counted. Table 1 shows the results.

  As apparent from Table 1, in the battery of Example 1 in which the protective tape on the side edge side is thicker than the protective tape on the metal thin plate side, the protective tape on the side edge side is thinner than the protective tape on the metal thin plate side. Internal short-circuiting is prevented compared to Comparative Example 1 and Comparative Example 2 in which no protective tape was bonded. This is because when the positive electrode plate is wound, the skeleton of the positive electrode substrate is locally broken, and even if it protrudes from the side edge part, the protective tape on the side edge part side is thickened, so that part of the broken skeleton This is thought to be because it did not penetrate the protective tape and the separator.

It is a fragmentary sectional view of the battery of one embodiment of the present invention. It is an expanded view of the positive electrode plate used for the battery of FIG. It is the figure which showed typically the connection area | region of the positive electrode plate and positive electrode current collecting plate in the battery of FIG.

Explanation of symbols

22 Electrode group 24 Positive electrode plate (first electrode plate)
26 Negative electrode plate (second electrode plate)
28 Separator 42 Positive substrate (conductive substrate)
44 Side edge (unfilled part)
50,52 Protection member (protective tape)

Claims (2)

A strip-shaped conductive substrate comprising a group of electrodes in which a separator is sandwiched between a first electrode plate and a second electrode plate and these are spirally wound, and the first electrode plate has a porous structure; In a battery having an active material filled in the conductive substrate,
The conductive substrate of the first electrode plate has a non-filled portion that is not filled with the active material on one side edge along the winding direction of the electrode group,
A thin metal plate superimposed on the unfilled portion;
Two protective members sandwiching the unfilled portion and the metal thin plate from both sides of the conductive substrate,
Of the protective members, the non-filled portion side protective member is thicker than the thin metal plate side protective member.   The battery according to claim 1, wherein the protective member is made of an adhesive tape.

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