JP2007242394A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery in which interior short circuit is surely prevented by a simple constitution. <P>SOLUTION: The battery is provided with an electrode group 22 formed by winding around a positive electrode plate and a negative electrode plate 28 in a spiral state via a separator 28, a connecting part 49 for current collection including a metal porous body 44 leading to the end part of the positive electrode plate positioned at one end side of the electrode group 22 and a metal thin plate 48 joined to one face of the metal porous body 44, a first protection tape 50 contacted with the inside face of the diameter direction of the connecting part 49 for current collection, and a second protection tape 52 which is contacted with the outside face of the diameter direction of the connecting part 49 for current collection and which has a length of nearly the same or more as the length of the outside face of the diameter direction of the connecting part 49 for current collection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery.

An alkaline storage battery such as a nickel metal hydride secondary battery used for a power source of an electric tool, an assist bicycle, an electric vehicle or the like requires excellent high rate discharge characteristics.
For example, Patent Document 1 discloses a battery excellent in this type of high-rate discharge characteristic, and the battery includes an electrode group in which a first electrode plate and a second electrode plate are wound in a spiral shape. A current collecting plate is disposed on one end side of the electrode group, and the current collecting plate is electrically connected to the first electrode plate of the electrode group.

More specifically, a current collector connection portion welded to the current collector plate is formed at the end portion of the first electrode plate located on one end side of the electrode group. The current collecting connection part is composed of a metal porous body (band-like connecting part) connected to the end of the first electrode plate and a metal thin plate joined to one side of the metal porous body. The protective tape is affixed. The protective tape prevents the strip-like connecting portion or the metal thin plate from breaking and breaking through the separator, and coming into contact with the second electrode plate to cause an internal short circuit. In addition, since these protective tapes are affixed on the connection part for current collection before winding, the length of the protection tape is matched with the length of the connection part for current collection before winding.
Japanese Unexamined Patent Publication No. 2000-21435

By the way, since the first electrode plate described above has a predetermined thickness, the surface on the radially outer side is stretched when wound in a spiral shape, and the surface on the radially outer side is more spirally oriented than the surface on the radially inner side. It gets longer. Similarly, in the current collector connection portion formed at the end of the first electrode plate, the radially outer surface is stretched, and the radially outer surface is longer.
For this reason, if the length of the current collecting connection portion is the same as the length of the protective tape attached to the radially outer surface of the current collecting connection portion before winding, The protective tape is shorter than the radially outer surface of the connecting part. In this case, the part of the current collecting connection part on the winding end side is not covered with the protective tape, and the thin metal plate or the metal porous body forming the current collecting connection part breaks through the separator and directly with the negative electrode plate. There is a risk of contact and an internal short circuit.

  The present invention has been made based on the above-described circumstances, and it is an object of the present invention to provide a battery in which an internal short circuit is reliably prevented with a simple configuration.

  In order to achieve the above object, according to the present invention, an electrode group formed by spirally winding a first electrode plate and a second electrode plate via a separator, and one end side of the electrode group are positioned. A current collector connecting portion including a metal porous body connected to an end portion of the first electrode plate and a metal thin plate joined to one surface of the metal porous body; and a first surface in contact with a radially inner surface of the current collector connecting portion. 1 is in contact with the outer surface in the radial direction of the current collector connection portion and has a length substantially equal to or greater than the length of the outer surface in the radial direction of the current collector connection portion in the spiral direction. A battery comprising the second protective member is provided (claim 1).

As a preferred aspect, before being wound, the second protective member is longer than the current collecting connection portion (Claim 2).
As a preferred embodiment, the protective member is made of an adhesive tape (Claim 3).

  According to the battery of claim 1 of the present invention, in the electrode group, the length of the second protective member is approximately equal to or greater than the length of the radially outer surface of the current collecting connection portion, whereby the current collecting connection The radially outer surface of the portion is covered with the second protective member over the entire area. As a result, in this battery, even if the metal porous body or the metal thin plate of the current collecting connection portion is broken, the broken portion is prevented from breaking through the separator by the second protective member, and the occurrence of an internal short circuit is ensured. To be prevented.

According to the battery of claim 2, before winding, the length of the second protective member after winding is made longer by making the length of the second protective member longer than the connecting portion for collecting current. It can be as simple and reliable as the length of the radially outer surface of the connecting portion.
According to the battery of claim 3, productivity is improved by using an adhesive tape as the protective member.

Hereinafter, a nickel-hydrogen secondary battery will be described as a battery according to an embodiment of the present invention.
This battery is, for example, an AA size cylindrical battery, and includes an outer can 10 having a bottomed cylindrical shape with one end opened as shown in FIG. 1, and the bottom wall of the outer can 10 has conductivity. Functions as a negative 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 is formed by spirally winding a strip-like positive electrode plate 24, a negative electrode plate 26 and a separator 28, and the separator 28 is sandwiched between the positive electrode plate 24 and the negative electrode plate 26.

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. A strip-shaped lead portion 40 is integrally formed on the positive electrode current collector plate 38, and the leading end of the lead portion 40 is welded to the lid plate 14, and the lid plate 14, the positive electrode current collector plate 38, and the lead portion 40 are interposed therebetween. 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 nickel electrode and has a conductive positive electrode substrate 42 with reference to FIG. The positive electrode substrate 42 is made of a metal porous body having 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 strip-shaped connecting portion 44 positioned on the cover plate 14 side of the electrode group 22. In other words, the positive electrode plate 24 is composed of a portion (main body portion 46) of the positive electrode substrate 42 excluding the belt-like connecting portion 44 and the positive electrode active material filled in the main body portion 46, and is connected to the end portion of the positive electrode plate 24 in a belt-like manner. The part 44 is connected continuously.

  The belt-like connecting portion 44 is compressed from both sides in the thickness direction and is thinner than the main body portion 46. For example, a strip-shaped metal thin plate 48 is welded to a radially outer surface of the strip-shaped connecting portion 44, and the metal thin plate 48 is wider than the strip-shaped connecting portion 44. The metal thin plate 48 extends beyond the separator 28 in the axial direction of the electrode group 22, and the end of the metal thin plate 48 is welded to the positive electrode current collector plate 38. Therefore, the strip-shaped connecting portion 44 and the metal thin plate 48 form a current collecting connection portion 49 for connecting the positive electrode plate 24 to the positive electrode current collecting plate 38.

The thickness of the thin metal plate 48 matches the level difference between the strip-shaped connecting portion 44 and the main body portion 46, and the outer surface of the thin metal plate 48 is substantially flush with the main body portion 46, that is, the radially outer surface of the positive electrode plate 24. There is no.
Protective tapes 50 and 52 are adhered to both surfaces of the current collecting connection portion 49, and these protective tapes 50 and 52 are also attached to the main body portion 46 adjacent to the current collecting connection portion 49 across the steps. It adheres over the entire length direction (spiral direction) of the electrical connection portion 49.

That is, as shown in the circle of FIG. 3, the radial inner surface and the radial outer surface of the current collecting connection portion 49 are the protective tape 50 up to the winding end end of the current collecting connection portion 49 as viewed in the spiral direction. , 52.
The protective tapes 50 and 52 are preferably made of an adhesive tape made of polypropylene or polyethylene, and the protective tape 50 on the side of the belt-like connecting portion 44 has a thickness of, for example, 60 to 100 μm, while the protective tape on the side of the metal thin plate 48 For example, 52 has a thickness of 20 to 50 μm. Therefore, the protective tape 50 on the belt-like connecting portion 44 side is thicker than the protective tape 52 on the metal thin plate 48 side.

Note that the end portions 54 and 54 of the negative electrode plate 26 positioned on the cover plate 14 side of the electrode group 22 protrude from the main body portion 46 of the positive electrode substrate 42 in the axial direction of the electrode group 22, and the separator 28 and the protection A part of the belt-like connecting portion 44 and the metal thin plate 48 is sandwiched between the tapes 50 and 52.
The electrode group 22 described above is formed by winding a belt-like positive electrode plate 24, a negative electrode plate 26, and a separator 28 in a spiral shape. Here, FIG. 4 shows the positive electrode plate 24 immediately before winding, and a current collecting connection portion 49 is already formed on the side of the positive electrode plate 24.

  Further, band-shaped protective tapes 50 and 52 are already attached to both sides of the current collecting connection portion 49, and the protective tape 52 is longer than the current collecting connection portion 49 and the protective tape 50 before winding. . More specifically, before winding, the position of the end portion on the winding start side is aligned between the current collecting connection portion 49 and the protective tape 50, 52, but the position of the end portion on the winding end side is They are arranged only between the current collecting connection portion 49 and the protective tape 50. The end of the protective tape 52 on the winding end side extends beyond the current collecting connection portion 49 and the end of the protective tape 50 on the winding end side.

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 20 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.
In the battery described above, in the electrode group 22, the length of the protective tape 52 is substantially the same as the length of the outer surface in the radial direction of the current collecting connection portion 49, and The surface is covered with the protective tape 52 over the entire area. As a result, in this battery, even if the metal thin plate 48 of the current collecting connection portion 49 is broken, the broken portion is prevented from breaking through the separator 28 by the protective tape 52, and the occurrence of an internal short circuit is surely prevented. Is done.

In the battery described above, before winding, the length of the protective tape 52 is made longer than that of the current collecting connection portion 49, so that the radially outer surface of the current collecting connection portion 49 extends during winding. Even so, the length of the protective tape 52 after winding can be easily and reliably made substantially equal to or more than the length of the radially outer surface of the current collecting connection portion 49.
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 one embodiment, the belt-like connecting portion 44 of the positive electrode substrate 42 is not filled with the positive electrode active material over the entire longitudinal direction, but a part of the belt-like connecting portion 44 may be filled with the positive electrode active material. . In this case, it is only necessary to compress only the remaining portion of the belt-like connecting portion 44 and weld the metal thin plate 48 to the compressed portion.
In one embodiment, the position of the end portion of the protective tape 52 on the winding end side is aligned with the position of the end portion of the current collecting connection portion 49, but the end portion of the protective tape 52 is connected to the current collecting connection portion 49. It may be beyond the end in the spiral direction.

  In one 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 belt-like connecting 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 one 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 strip-shaped connecting portion 44 of the positive electrode plate 24 protrudes toward the bottom wall of the outer can 10.
In one embodiment, the metal thin plate 48 protrudes from the separator 28 rather than the belt-like connecting portion 44. May be welded to the positive electrode current collector plate 38.

In the embodiment, the thin metal plate 48 is joined to the outer side in the radial direction of the strip-shaped connecting portion 44, but the thin metal plate 48 may be joined to the inner side in the radial direction of the strip-shaped connecting portion 44.
In one 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, a strip-shaped connecting portion is formed on the negative electrode substrate, and a thin metal plate is formed on the strip-shaped connecting portion. And a protective tape may be adhered 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 electrode group may have an elliptical cross-sectional shape by pressing and deforming from both sides in the radial direction.

Example 1 and Comparative Example 1
1. Production of Battery (1) Production of Positive Electrode After conducting a conductive treatment on a sponge-like organic porous body which is an open-cell polyurethane foam, it was immersed in a plating solution in an electrolytic bath and nickel-plated. 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.

  Meanwhile, 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 mixture was mixed, 50 parts by mass of an aqueous hydroxypropylcellulose solution (solid content: 0.2% by mass) 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 the active material slurry was dried, 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. Thereafter, the side edge portion was rolled again to form a strip-like connecting portion having a thickness of about 0.5 mm.
Thereafter, a nickel ribbon having a thickness of 0.1 mm and a width of 3 mm is connected to one surface of the belt-like connecting portion by resistance electric welding to form a current collecting connection portion. Table 1 is formed on both surfaces of the current collecting connection portion. A protective tape (Nichiban Co., Ltd., polypropylene adhesive tape) having the length before winding shown in FIG.

(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 aqueous potassium hydroxide 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 a first example and a comparative example 1, a cylindrical nickel-metal hydride secondary battery having a nominal capacity of 1200 mAh is obtained. 1000 pieces were manufactured.

2. Short-circuit evaluation test Measure the inter-terminal voltage of the batteries of the obtained examples and comparative examples. If the inter-terminal voltage is 0.1 V or less, it is judged that an internal short circuit has occurred, and out of 1,000 batteries that have an internal short circuit. I counted the number. Table 1 shows the results.

  As is apparent from Table 1, the length before winding of the protective tape positioned on the radially outer side is longer than the length before winding of the protective tape positioned on the current collecting connection portion and radially inside. In the battery, the occurrence of an internal short circuit is prevented as compared with Comparative Example 1 in which the length of the current collector connection portion and the length of the protective tape before winding are the same.

It is a fragmentary sectional view of the battery of one embodiment of the present invention. It is the figure which expanded and showed roughly the connection part of the positive electrode plate and positive electrode current collecting plate in the battery of FIG. FIG. 2 is a cross-sectional view of an electrode group used in the battery of FIG. 1, and the inside of a circle schematically shows an enlarged vicinity of a winding end end portion of a positive electrode plate. It is a perspective view which shows schematically the positive electrode plate just before winding.

Explanation of symbols

22 Electrode group 24 Positive electrode plate (first electrode plate)
26 Negative electrode plate (second electrode plate)
28 Separator 44 Band-shaped connecting part (metal porous body)
48 Thin metal plate 49 Current collector connection 50 Protective tape
52 protective tape (second protective member)

Claims (3)

An electrode group formed by spirally winding the first electrode plate and the second electrode plate via a separator;
A current collector connecting portion including a metal porous body connected to an end portion of the first electrode plate located on one end side of the electrode group, and a metal thin plate bonded to one surface of the metal porous body;
A first protective member in contact with a radially inner surface of the current collecting connection portion;
A second protective member that is in contact with the radially outer surface of the current collecting connection portion and has a length substantially equal to or greater than the length of the radially outer surface of the current collecting connection portion in the spiral direction. A battery comprising:   The battery according to claim 1, wherein the second protective member is longer than the current collecting connection portion before being wound.   The battery according to claim 1, wherein the protective member is made of an adhesive tape.

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