JP2000323117A - Cylindrical storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage battery having improved efficient discharge characteristic by collecting electricity from plates of all parts of an electrode group even in the case where a positive electrode collector or a negative electrode collector are formed at a degree of dimension capable of avoiding contact with a metal outer can or without using collectors. SOLUTION: This spiral electrode is formed by bending core exposed parts 11a of positive plates 12 projected in an upper part of a spiral electrode group 10 in order from the inner peripheral part toward the peripheral part at a right angle against the direction of the inner peripheral part of the spiral electrode group 10, and overlapping the core exposed parts 11a of the outer peripheral part with the core exposed parts 11a of the inner peripheral part. These overlapped core exposed parts 11a are flattened by pressurization, and the positive collectors are welded to the top surface of each core exposed part 11a, and the negative collectors are welded to a lower surface of each core exposed part 13a of the negative plates 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive connection structure for a nickel-hydrogen battery, a nickel-cadmium battery, a lithium ion battery, and the like.

[0002]

2. Description of the Related Art Conventionally, a storage battery such as a nickel-hydrogen storage battery, a nickel-cadmium storage battery, and a lithium-ion storage battery has a positive electrode plate and a negative electrode plate which are vertically displaced from each other and spirally wound through a separator. After forming the electrode group, a positive electrode current collector is welded to the exposed core body at the upper edge of the positive electrode plate of the spiral electrode group, and the negative electrode current collector is welded to the exposed core body at the lower edge of the negative electrode plate of the spiral electrode group. A spiral electrode body is formed by welding. Thereafter, the spiral electrode body is inserted into a metal outer can also serving as the negative electrode terminal, the negative electrode current collector is electrically connected to the bottom of the metal outer can, and the positive electrode current collector is also sealed with the positive electrode terminal. It was designed to be electrically connected to the body.

As described above, when the negative electrode current collector of the spiral electrode body is electrically connected to the bottom of the metal outer can and the positive electrode current collector of the spiral electrode body is welded to the sealing body, the positive electrode plate is removed from the positive electrode plate. Since the current distribution to the terminal (sealing body) and the current distribution from the negative electrode plate to the negative electrode terminal (metal outer can) become uniform, a storage battery with improved high-rate discharge characteristics can be obtained.

[0004]

In the storage battery constructed as described above, the metal outer can also serves as the negative electrode terminal. Causes a short circuit. For this reason, it is necessary that the positive electrode current collector be large enough not to come into contact with the metal outer can. In addition, even if the negative electrode current collector contacts the metal outer can, no internal short circuit occurs.However, if the outer diameter of the negative electrode current collector is equal to the inner diameter of the metal outer can, the spiral electrode body is Not only is it difficult to insert into the outer can, but if the negative electrode current collector is not welded to the spiral electrode group at the correct position, the spiral electrode body will not be inserted into the outer can, so the negative electrode current collector will not be inserted. Also had to be of such a size that it did not come into contact with the metal outer can.

However, if the positive electrode current collector or the negative electrode current collector is made small enough not to contact the metal outer can, the positive electrode plate and the positive electrode current collector or the positive electrode current collector or the negative electrode plate and the negative electrode current collector are welded to each other. There is a portion where the current collector or the negative electrode current collector is not welded. If a portion that is not welded to the positive electrode current collector or the negative electrode current collector occurs, the current distribution in the current collecting path from the positive electrode plate to the positive electrode current collector or the current distribution in the current collecting path from the negative electrode plate to the negative electrode current collector may be impaired. Uniformity occurs and a voltage drop occurs due to an increase in contact resistance of a portion not welded to the positive electrode current collector or the negative electrode current collector.

[0006] Such a voltage drop is not so problematic when charging / discharging with a small current, but when charging / discharging with a large current of several tens to several hundreds of amps, the above-described connection portion is not used. However, there is a problem that a large voltage drop occurs due to an increase in the contact resistance and the operating voltage decreases. If the operating voltage decreases, a high voltage cannot be obtained,
There also arises a problem that the high-rate discharge characteristics deteriorate. Therefore,
The present invention has been made in view of the above-described problems, and has a size such that the positive electrode current collector or the negative electrode current collector is not in contact with the metal outer can, or the positive electrode current collector or the negative electrode current collector The purpose of the present invention is to make it possible to obtain a storage battery excellent in high-rate discharge characteristics by using a current collecting structure capable of collecting current from the electrode plates of all the parts of the spiral electrode group without using the electrode. is there.

[0007]

Means for Solving the Problems and Action / Effects Therefor, according to the present invention, the storage battery according to the present invention includes a core exposed portion at the edge of the positive electrode plate or a core exposed portion at the edge of the negative electrode plate of the spiral electrode group. At least one exposed portion of the core is bent. In this way, if the exposed core is bent, the bent exposed cores come into contact with each other. Without using the electrode, current can be collected from the electrode plates at all portions of the spiral electrode group. For this reason, the current distribution from the positive electrode plate or the negative electrode plate to the external terminal (sealing body or outer can) becomes uniform, and the high-rate discharge characteristics are improved.

The bent core exposed portion is bent toward the inner circumferential direction of the spiral electrode group, and the bent core exposed portion is bent in the inner circumferential direction of the spiral electrode group. When the exposed core portion overlaps with the exposed portion and is formed substantially flat, the exposed core portion does not protrude from the spiral electrode group, so that the current collector contacts the metal outer can. The current collection from the electrode plate of the spiral electrode group to the external terminal is performed well, and the electrode group can be easily inserted into the outer can, even if the size is not large or the current collector is not used. Becomes

If the current collectors are welded to the exposed core portions overlapping each other, current can be collected from all the exposed core portions and the current can be uniformly collected. The current distribution from the plate to the external terminal (sealing body or outer can) becomes more uniform, and the high-rate discharge characteristics are improved.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment in which a cylindrical storage battery according to the present invention is applied to a nickel-metal hydride storage battery. FIG. 1 is a cross-sectional view showing a cross section of an electrode group of an example, and FIG. 2 is a cross-sectional view showing a cross section of an electrode group of a comparative example (conventional example).

1. 1. Fabrication of Spiral Electrode Body (1) Example As shown in FIG. 1, a nickel sintered substrate formed by sintering nickel powder on a core body 11 was impregnated with a positive electrode active material mainly composed of nickel hydroxide. , Dried, and rolled to a predetermined thickness to form a nickel positive plate (for example,
8.5 mm) 12 was produced. On the other hand, a punched metal (core) 13 is filled with a paste-like negative electrode active material made of a hydrogen storage alloy, dried, and then rolled to a predetermined thickness to form a hydrogen storage alloy negative plate (for example, having a height of 4 mm).
8.5 mm) 14 was produced.

The nickel positive electrode plate 12 and the hydrogen storage alloy negative electrode plate 14 manufactured as described above are separated from the nickel positive electrode plate 12 and the hydrogen storage The negative electrode plate 14 is slightly shifted in the vertical direction, that is,
The upper end of the nickel positive electrode plate 12 projects upward and the lower end of the hydrogen-absorbing alloy negative electrode plate 14 projects downward, and the spirally wound electrode group (height: Is 51.1 to 51.2 mm and the diameter is about 30 mm) 10. Therefore,
At the upper part of the spiral electrode group 10 manufactured in this manner, a core exposed part (for example, having a width of about 1 mm) 11a from which the core 11 of the nickel positive electrode plate 12 is exposed, and hydrogen is formed under the exposed part. A core-exposed portion (for example, about 1 mm in width) 13a of the storage alloy negative electrode plate 14 from which the core 13 is exposed protrudes.

Next, the core exposed portion 11a of the nickel positive electrode plate 12 protruding above the spiral electrode group 10 is sequentially moved from the inner peripheral portion to the outer peripheral portion of the spiral electrode group 10. After being bent at a substantially right angle in the direction of the peripheral portion, the core exposed portion 11a of the outer peripheral portion is folded on the core exposed portion 11a of the inner peripheral portion, and then these folded core exposed portions 11a are folded.
a was pressed and flattened. Thereafter, a positive electrode current collector (not shown) is welded to the upper surface of the flattened core exposed portion 11a, and the core exposed portion 13a of the hydrogen storage alloy negative electrode plate 14 is welded.
A negative electrode current collector (not shown) was welded to the lower surface of the spirally wound electrode body of Example.

(2) Comparative Example Similarly, as shown in FIG. 2, a nickel sintered substrate formed by sintering nickel powder on a core 21 is impregnated with a positive electrode active material containing nickel hydroxide as a main component. , After drying, rolling to a predetermined thickness and nickel positive plate (for example,
22 with a height of 48.5 mm). On the other hand, a punched metal (core) 23 is filled with a paste-like negative electrode active material made of a hydrogen storage alloy, dried, and then rolled to a predetermined thickness to form a hydrogen storage alloy negative plate (for example, having a height of 48 mm). 0.5 mm) 24 was produced.

The nickel positive electrode plate 22 and the hydrogen storage alloy negative electrode plate 24 produced in this way are interposed between the nickel positive electrode plate 22 and the hydrogen storage alloy The negative electrode plate 24 is slightly shifted in the vertical direction, that is,
The spirally wound electrode group (having a height of 51.1 to 51.2) is wound so that the core body 21 projects upward and the core body 23 projects downward, and the outermost periphery is wound as the separator 25.
mm, having a diameter of about 30 mm) 20. A core exposed portion (eg, about 1 mm in width) 21a from which the core 21 of the nickel positive electrode plate 22 is exposed projects above the spiral electrode group 20 manufactured in this manner, and hydrogen is exposed below the core exposed portion 21a. A core exposed portion 23a (for example, having a width of about 1 mm) where the core 23 of the storage alloy negative electrode plate 24 is exposed protrudes. Then, similarly to the above-described embodiment, the core exposed portion 21 of the positive electrode plate 22 slightly protruding from the spiral electrode group 20 is formed.
a and the positive electrode current collector were welded, and at the same time, the core exposed portion 23a of the negative electrode plate 24 and the negative electrode current collector were welded to produce a spiral electrode body of a comparative example.

The positive electrode current collector has a substantially circular main body,
A substantially rectangular current collecting lead extending from the main body, and having an opening for liquid injection at the center of the main body, and a plurality of openings around the opening for liquid injection. And each of the openings has a projecting edge projecting below the opening at a side edge thereof. Further, the negative electrode current collector includes a substantially circular main body, which has a large number of openings, and a protruding edge protruding above the opening at a side edge of each opening. Here, the diameters of the substantially circular main body portions of the positive electrode current collector and the negative electrode current collector are formed slightly smaller than the inner diameter of the bottomed cylindrical metal outer can, and the diameter of each of the spiral electrode groups 10 and 20 is reduced. (About 30mm)
Less than.

2. Preparation of nickel-metal hydride storage battery
The spirally wound electrode bodies of the above-described Examples and Comparative Examples are inserted into a metal outer can, and a welding electrode is inserted through an opening provided at the center of the positive electrode current collector to make contact with the negative electrode current collector. At the same time, the welding electrode was brought into contact with the bottom of the metal outer can to spot-weld the negative electrode current collector and the bottom of the metal outer can.

On the other hand, a sealing body (not shown) composed of a positive electrode cap and a lid (a pressure valve is disposed between the positive electrode cap and the lid) was prepared and provided on the positive electrode current collector. The current collecting lead is brought into contact with the bottom of the lid of the sealing body, and the bottom of the lid and the current collecting lead are welded. Then, an electrolytic solution made of a 30% by weight aqueous solution of potassium hydroxide (KOH) is placed in a metal outer can. Inject the liquid and seal the sealing body with an insulating gasket (insulator)
And placed on the opening of the outer can through the opening, and the opening is caulked toward the sealing body and sealed to form a nominal capacity of 6.5 Ah.
Then, each nickel-hydrogen storage battery of Example and Comparative Example of D size was produced.

3. Working voltage test The nickel and nickel alloys of Examples and Comparative Examples produced as described above were used.
After activating each of the three hydrogen storage batteries, each of the batteries was charged with a charging current of 0.2 C (1.3 A) for 8 hours (160% charging). Then
Each of these batteries was charged at 0.2C (1.3A), 1C (6.5A).
A) and 4C (26A) with a discharge current of 1.
The battery was discharged until the voltage reached 0 V, the voltage (operating voltage) at a discharge capacity of 50% was measured, and the average value of the operating voltages of the three nickel-metal hydride storage batteries was determined. The result was as follows.

[0020]

[Table 1]

As is apparent from Table 1, the nickel-hydrogen storage battery of the embodiment has an improved operating voltage at a higher rate of discharge than the nickel-hydrogen storage battery of the comparative example.
This is because in the nickel-hydrogen storage battery of the comparative example, the core exposed portion 2 of the positive electrode plate 22 at the outermost periphery of the spiral electrode group 20
1a is not connected to the positive electrode current collector,
It is considered that the operating voltage in the high-rate discharge was lowered because the current collection from each part could not be performed uniformly.

On the other hand, in the nickel-metal hydride storage battery of the embodiment, the core exposed portion 11a of the positive electrode plate 12 at the outermost periphery of the spiral electrode group 10 is bent at substantially a right angle to form the core at the inner periphery. Since it is connected to the exposed portion 11a and is connected to the positive electrode current collector, current collection from each portion of the positive electrode plate 12 becomes uniform, and the contact area between the core exposed portion 11a and the positive electrode current collector increases. It is considered that the operating voltage in the high-rate discharge was improved because of this.

As described in detail above, in the present invention, since the core exposed portion 11a of the positive electrode plate 12 is bent, the current collector is made small enough not to come into contact with the metal outer can. Positive electrode plates 1 in all parts of spiral electrode group 10
2, the current can be collected, and the current distribution from the positive electrode plate 12 to the external terminal (sealing body) becomes uniform. In addition, since the bent core exposed portions 11a overlap each other, the contact area between the core exposed portion 11a and the positive electrode current collector increases, and the contact resistance decreases, so that the high-rate discharge characteristics are improved. .

In the above-described embodiment, the core exposed portion 11a of the positive electrode plate 12 extending above the spiral electrode group 10 is bent, and these are sequentially folded toward the inner peripheral portion of the spiral. Has been described, but the spiral electrode group 10
The same effect can be expected even if the core exposed portion 13a of the negative electrode plate 14 extending to the lower portion of the spiral is bent and these are sequentially folded toward the inner peripheral portion of the spiral.

Further, both the core exposed portion 11a of the positive electrode plate 12 extending above the spiral electrode group 10 and the core exposed portion 13a of the negative electrode plate 14 extending below are bent, and these are successively spiraled. If you fold it towards the inner circumference,
Since current collection from both the positive electrode plate 12 to the positive electrode terminal and from the negative electrode plate 14 to the negative electrode terminal becomes uniform and the contact resistance of both decreases, high-rate discharge characteristics are further improved.

Further, in the above-described embodiment, an example has been described in which all the core exposed portions 11a extending from the spiral electrode group 10 are bent and these are sequentially folded toward the inner peripheral portion of the spiral. Even if only the outermost peripheral portion of the core exposed portion 11a extending from the spiral electrode group 10 is bent and the bent core exposed portion 11a is connected to the current collector, substantially the same effect can be obtained. Can be expected.

Further, in the above-described embodiment, all of the core exposed portions 11a extending from the spiral electrode group 10 are bent, and these are sequentially folded toward the inner peripheral portion of the spiral, and then the upper portion is bent. Although the example in which the positive electrode current collector is welded is described above, almost the same effect can be expected without using the positive electrode current collector.

In the above-described embodiment, an example in which the present invention is applied to a nickel-metal hydride storage battery has been described. However, the present invention can be applied to nickel-cadmium storage batteries, lithium-ion storage batteries, and the like in addition to nickel-metal hydride storage batteries. It is clear that the same effect can be obtained by applying to a sealed storage battery.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a cross section of an electrode group according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a cross section of an electrode group of a conventional example (comparative example).

[Explanation of symbols]

Reference numeral 10: spiral electrode group, 11: core, 11a: core exposed part, 12: positive electrode plate, 13: punching metal (core),
13a: core exposed portion, 14: negative electrode plate, 15: separator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigekazu Yasuoka 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Takaaki Ikemachi 2-chome Keihanhondori, Moriguchi-shi, Osaka No.5-5 Sanyo Electric Co., Ltd. F-term (reference) 5H022 AA04 AA09 AA18 BB02 BB16 CC08 CC13 CC19 KK03 5H028 AA01 AA05 BB01 BB04 BB05 CC07 CC08 CC12 5H029 AJ02 BJ02 BJ14 CJ01 CJ04 DJ05 DJ02 DJ02

Claims (3)

[Claims] A spirally wound electrode group in which a positive electrode plate and a negative electrode plate are vertically shifted from each other and spirally wound through a separator is provided in a metal outer can also serving as an external terminal of one of the electrodes. What is claimed is: 1. A cylindrical storage battery comprising a sealing body serving also as an external terminal of the other electrode for sealing an opening of an outer can with an insulator interposed therebetween, wherein a core exposed portion of the positive electrode plate or the negative electrode plate of the spiral electrode group Wherein at least one of the core exposed portions is bent. 2. The bent core exposed portion is bent toward the inner circumferential direction of the spiral electrode group, and the bent core exposed portion is bent in the inner circumferential direction of the spiral electrode group. Overlap with each other on the exposed part of the core,
2. The cylindrical storage battery according to claim 1, wherein the core exposed portions overlapping each other are formed substantially flat. 3. The cylindrical storage battery according to claim 1, wherein a current collector is welded to the exposed core portions overlapping each other.