JP2005294010A - Alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkaline battery which makes a capacity higher and can surely prevent an electrode core body from rupturing when winding/forming an electrode group. <P>SOLUTION: The alkaline battery has the electrode group composed of a negative electrode, a positive electrode, and a separator. The negative electrode has a core body 16, over which a number of holes 18 are distributed, where an aperture ratio in surface of the core body 16 is 0.4 or more, and an aperture ratio in cross-section is reduced to 1.2 or less times the aperture ratio in surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an alkaline storage battery such as a nickel-cadmium battery or a nickel-hydrogen battery, and more particularly to a cylindrical alkaline storage battery.

  This type of alkaline storage battery includes an electrode group housed in its outer can, and this electrode group is formed by winding a negative electrode and a positive electrode in a spiral shape with a separator interposed therebetween. In order to increase the capacity of such an alkaline storage battery, the amount of the active material of the positive electrode and the negative electrode may be increased, but the outer can is limited by its size, so the diameter of the electrode group, that is, It is difficult to increase the volume of the whole positive electrode and negative electrode.

Therefore, it is conceivable to reduce the volume of the negative electrode core as much as possible and increase the amount of the active material that can be supported on the core, and an alkaline storage battery in which the negative electrode core is formed from a thin sheet of punched metal. Known (for example, Patent Documents 1 and 2).
Moreover, the punching metal of Patent Documents 1 and 2 has an array pattern of holes in which the centers of three adjacent holes are the vertices of an equilateral triangle or an isosceles triangle. It is considered that it is wound in a state close to a perfect circle and can secure the winding property.
Japanese Patent Laid-Open No. 3-141554 JP 7-73874 A

  In order to increase the amount of active material supported on the core, the value obtained by dividing the total opening area of the holes by the core surface area (the sum of the total opening area and the non-porous area), that is, the surface opening ratio of the core However, if the surface area ratio is 0.4 or more, the tensile strength of the core is insufficient, and when the negative electrode (electrode group) is wound, a part of the core is broken, particularly at the end thereof. It becomes easy to invite. For this reason, the surface area ratio of the core must be made smaller than 0.4, and the active material cannot be sufficiently increased.

  The present invention has been made based on the above-mentioned circumstances, and the object thereof is a high capacity type that can ensure a sufficiently large surface opening ratio of the core body and that does not cause breakage of the core body when the electrode group is wound. It is to provide an alkaline storage battery.

  In order to achieve the above object, the core of the negative or positive electrode of the alkaline storage battery of the present invention is exposed intermittently along the width direction of the core when viewed in a cross section intersecting with the winding direction. It has a cross-sectional pattern, and the cross-sectional opening ratio of the core body is defined by the maximum value of the value obtained by dividing the total length of the exposed portions of the holes along the width direction of the core body by the cross-sectional pattern by the width of the core body When this is done, the core body includes at least a cross-sectional pattern in which the surface aperture ratio is 0.4 or more and the cross-section aperture ratio is 1.2 times or less of the surface aperture ratio (Claim 1).

Here, when the holes are distributed in one arrangement pattern as shown in FIG. 5, the surface opening ratio is the area (B region) having the holes in FIG. It is defined by a value divided by the body surface area (the total of the total area of the opening and the total area of the non-porous part).
On the other hand, when the holes are distributed in a plurality of arrangement patterns as shown in FIG. 6, the sections are arranged for each section (that is, B, D, F areas) having a continuous arrangement of holes having the same period. Divided by a line intersecting the winding direction of the core body, the surface opening ratio for each section, the total opening area of the holes in the section, the surface area of the core body in the section (the total area of the opening and the non-porous) What is necessary is just to define by the value which remove | divided by the sum total of a part total area.

If a part of the core body, that is, a portion that is easily broken at the time of winding has the above-described cross-sectional pattern of the surface opening ratio and the cross-sectional opening ratio, even if the surface opening ratio is larger than 0.4, Since a non-porous region is sufficiently secured in the cross section, the core body is reliably prevented from being broken. The surface aperture ratio is more preferably 0.45 or more.
The core is a negative electrode core (Claim 2), and the thickness thereof is preferably 15 to 65 μm in order to reduce the volume of the core (Claim 3). Further, the core is formed of a nickel-plated sheet-like punching metal or a perforated nickel sheet.

  Further, the holes can be substantially circular or substantially elliptical, and the distribution of the holes is such that the center between the holes adjacent to each other in the winding direction of the core body is the base of an isosceles triangle and the cores with respect to these holes. It has an arrangement pattern in which the centers of holes adjacent in the width direction of the body are the vertices of the isosceles triangle, and the apex angle of the isosceles triangle is larger than the base angle. Having such a hole arrangement pattern is advantageous in obtaining a cross-sectional aperture ratio of 1.2 times or less of the surface aperture ratio.

Specifically, in the case of the above arrangement pattern, when the length of the base of the isosceles triangle is represented by d and the average diameter of the holes is represented by l,
d = 3 ^1/2 × l × σ
0.96 ≦ σ ≦ 1.04
(Claim 6), and the apex angle of the isosceles triangle is in the range of 75 ° to 105 ° (Claim 7).

  More specifically, the average diameter l of the hole is in the range of 0.5 mm ≦ l ≦ 2.5 mm (Claim 8), and the side edge of the core body along the winding direction is formed by a part of the hole. It is desirable to have an uneven shape.

  According to the alkaline storage battery of claims 1 to 9, at least a part of the core of the negative electrode or the positive electrode has a surface opening ratio of 0.4 or more and a cross-sectional opening ratio of 1.2 times or less of the surface opening ratio. Since the given cross-sectional pattern is provided, it is possible to prevent breakage at the time of winding while sufficiently ensuring the surface opening ratio of the core, and the core greatly contributes to the increase in capacity of the alkaline storage battery.

FIG. 1 shows a sealed cylindrical alkaline storage battery such as a nickel-cadmium battery or a nickel-hydrogen battery. This battery includes a metal outer can 2, and one end of the outer can 2 is open. In the outer can 2, an electrode group 4 is accommodated together with an electrolytic solution, and the electrode group 4 is formed by interposing a separator 10 between a negative electrode 6 and a positive electrode 8 and winding them in a spiral shape.
As is apparent from FIG. 1, the opening end of the outer can 2 is closed by a sealing body 12, and the sealing body 12 has a positive terminal 14 at the center thereof, and the negative terminal forming a pair with the positive terminal 14 is the outer can 2. Is formed at the bottom.

FIG. 2 shows a core 16 of the negative electrode 6, and the core 16 is made of a nickel-plated sheet-like punching metal or a perforated nickel sheet. Therefore, the core body 16 has a large number of holes 18, and these holes 18 are preferably circular or oval, or have a shape close to these circles and ellipses. In the illustrated embodiment, the hole 18 is substantially a perfect circle.
The holes 18 described above are distributed in a predetermined arrangement pattern over the entire area of the core body 16 or a part thereof. Specifically, the arrangement pattern is formed from a plurality of hole rows extending in parallel with each other in the winding direction of the negative electrode 6, and the holes 18 of the adjacent hole rows are shifted from each other in the winding direction. Accordingly, as seen from the aa, bb, and cc cross sections of the core body 16 in FIG. The body 16 is exposed intermittently in the width direction, and the exposed pattern of the holes 18, that is, the cross-sectional pattern, differs depending on the position of the cross section of the core body 16.

In FIG. 3, reference symbol T indicates the thickness of the core body 16, and the thickness T is 15 μm to 65 μm.
Here, the surface opening ratio R ₁ of the core body 16 is defined by a value obtained by dividing the total opening area of the hole 18 by the core body surface area (the sum of the total opening area and the total non-hole area), and the core body. When the sectional opening ratio R ₂ of 16 is defined by the maximum value of the value obtained by dividing the total length of the exposed portions of the holes 18 along the width direction of the core body 16 by the width of the core body 16 in the cross-sectional pattern, The aperture ratio R ₁ is 0.4 or more, preferably 0.45 or more, and the cross-section aperture ratio R ₂ is suppressed to 1.2 times or less of the surface aperture ratio R1 at any cross-sectional position. .

  Specifically, as shown in FIG. 4, the distribution of the holes 18 is such that a line segment connecting the centers of two holes 18 adjacent to each other in the winding direction of the core body 16 is the base of the isosceles triangle A, and These holes 18 have an array pattern in which the center of one hole 18 adjacent in the width direction of the core body 16 is an apex of an isosceles triangle A. The apex angle α of the isosceles triangle A is larger than the base angle β, and is in the range of 75 ° to 105 °.

Furthermore, when the diameter (average diameter) of the hole 18 and the length of the base of the isosceles triangle A are respectively represented by l and d, the base length d satisfies the relationship of the following equation.
d = 3 ^1/2 × l × σ
0.69 ≦ σ ≦ 1.04
The diameter l of the hole 18 is in the range of 0.5 mm to 2.5 mm. Here, when the diameter l is smaller than 0.5 mm, the interval between the holes 18 defining the hypotenuse of the isosceles triangle A becomes too narrow, and these holes 18 may be connected when the core body 16 is drilled. On the other hand, when the diameter l is larger than 2.5 mm, it becomes difficult to hold the active material in the hole 18, and the active material is dropped when the negative electrode 6 is wound.

  Table 1 below shows the core group 16 of Examples E1 to E10 and the core bodies of Comparative Examples C1 to C10, respectively, and the electrode group 100 when winding the negative electrode (electrode group) using these core bodies. The result of having measured the fracture | rupture number N of the core body per piece is shown.

In Table 1, H indicates the height of the isosceles triangle A (see FIG. 4), M indicates the amount of mass loss before and after activation when the battery is assembled using the wound electrode group, and the larger the value, Battery life is shortened.
As is clear from Table 1, the core body 16 of Examples E1 to E10 has a cross-sectional aperture ratio R ₂ that is suppressed to 1.2 times or less of the surface aperture ratio R ₁ , so when the negative electrode 6 is wound, Breakage of the core body 16 can be prevented almost certainly. On the other hand, the cores of Comparative Examples C1, C2, C5 to C7 have a cross-sectional opening ratio R ₂ exceeding 1.2 times the surface opening ratio R ₁ , so that the core body is easily broken during winding. I understand that.

When the core is its winding of Comparative Example C3,4,8～10, although not subject to breakage, less than all the surface open area ratio R ₁ of the Comparative Examples 0.4, a high-capacity alkaline storage batteries I can't plan.
On the other hand, unlike the other examples, the core body 16 of Example E8 shows a slight breakage, which seems to be caused by the surface opening ratio R ₁ being too large. Therefore, in order to increase the capacity of the alkaline storage battery and reliably prevent the core body 16 from being broken, the surface opening ratio R ₁ is preferably in the range of about 0.45 to about 0.60.

The present invention is not limited to the above-described embodiments, and various modifications can be made.
In the case of the core body 16 shown in FIG. 2, a part of the hole 18 does not exist on both side edges along the winding direction. However, the both side edges are located at the positions indicated by the one-dot chain line in FIG. For example, the amount of the active material carried by the core body 16 can be further increased, which is preferable for increasing the capacity of the alkaline storage battery.

The core body 16 of the example has a portion having a surface opening ratio R ₁ of 0.4 or more and a cross-sectional opening ratio R ₂ of 1.2 times or less of the surface opening ratio R ₁ over the entire winding direction. However, the said part may be provided only in the area | region of the core 16 which is easy to fracture | rupture at the time of winding, specifically, the both ends of the core 16.
Furthermore, the present invention can be similarly applied to a positive electrode core of an alkaline storage battery.

It is the perspective view which fractured | ruptured and showed a part of alkaline storage battery. It is the figure which showed a part of core in the negative electrode of FIG. 2A and 2B are cross-sectional views taken along line aa in FIG. 2, FIG. 2B is a cross-sectional view taken along line bb in FIG. 2, and FIG. It is sectional drawing which follows the cc line in 2. FIG. It is a figure for demonstrating the arrangement pattern of the hole which the core of FIG. 2 has. It is a figure for demonstrating the definition of a surface aperture ratio. It is a figure for demonstrating the definition of a surface aperture ratio.

Explanation of symbols

2 exterior can 4 electrode group 6 negative electrode 8 positive electrode 10 separator 16 core 18 hole A isosceles triangle T thickness α apex angle β base angle l diameter (average diameter)
d Base length H Height of isosceles triangle A

Claims (9)

An electrode group is housed in an outer can, and the electrode group is formed by winding them in a spiral shape with a separator interposed between the negative electrode and the positive electrode, and at least one of the negative electrode and the positive electrode is an active material thereof In an alkaline storage battery having a core made of a perforated sheet in which a large number of holes are formed to support
The core body has a cross-sectional pattern in which holes are intermittently exposed along the width direction of the core body when viewed in a cross section intersecting with the winding direction;
When the cross-sectional opening ratio of the core body is defined by the maximum value of the value obtained by dividing the total length of the exposed portions of the holes along the width direction of the core body by the cross-sectional pattern by the width of the core body, The alkaline storage battery according to claim 1, wherein the core includes at least a cross-sectional pattern having a surface aperture ratio of 0.4 or more and a cross-section aperture ratio of 1.2 times or less of the surface aperture ratio.   The alkaline storage battery according to claim 1, wherein the core is a core of the negative electrode.   The alkaline storage battery according to claim 2, wherein the core has a thickness of 15 μm to 65 μm.   The alkaline storage battery according to claim 2, wherein the core is made of one of a nickel-plated sheet-like punching metal and a perforated nickel sheet. The hole has a substantially circular or substantially elliptical shape,
The distribution of the holes is such that the interval between the centers of the holes adjacent to each other in the winding direction of the core is an isosceles triangle base, and the center of the hole adjacent to the holes in the width direction of the core is the isosceles triangle. Has an array pattern as the vertex of
The alkaline storage battery according to any one of claims 2 to 4, wherein an apex angle of the isosceles triangle is larger than a base angle. When the length of the base of the isosceles triangle is d and the average diameter of the holes is l, the following formula is given: d = 3 ^1/2 × l × σ
0.96 ≦ σ ≦ 1.04
The alkaline storage battery according to claim 5, wherein:   The alkaline storage battery according to claim 5 or 6, wherein an apex angle of the isosceles triangle is not less than 75 ° and not more than 105 °.   The alkaline storage battery according to claim 5, wherein an average diameter l of the holes is in a range of 0.5 mm ≦ l ≦ 2.5 mm.   The alkaline storage battery according to any one of claims 1 to 8, wherein a side edge of the core body along the winding direction has an uneven shape due to a part of the hole.

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