JP4610395B2 - battery - Google Patents

Description

  The present invention relates to an alkaline storage battery such as a nickel-cadmium storage battery or a nickel-hydrogen storage battery, or a battery such as a lithium ion battery, and in particular, a positive electrode and a negative electrode which are arranged to face each other with a separator interposed between them. The present invention relates to a battery in which an electrode group is housed in an outer can together with an electrolyte, and an opening of the outer can is sealed with a sealing body.

  Alkaline storage batteries such as nickel-cadmium storage batteries and nickel-hydrogen storage batteries have come to be used as batteries for large current applications such as electric vehicles, electric motorcycles, assist bicycles, and electric tools. Alkaline storage batteries used for this type of application are required to have high output characteristics and high energy density. In order to achieve high output characteristics, it is necessary to reduce the resistance of the current collecting component, and it is necessary to close contact between the current collector and the electrode substrate at the end of the electrode plate. In addition, since the current collector may come off due to vibration or the like, it is necessary to increase the welding strength between the current collector and the electrode substrate.

  In this type of alkaline storage battery, a positive electrode plate and a negative electrode plate are usually spirally wound through a separator to form an electrode group, and then the electrode substrate of the negative electrode plate of this electrode group is welded to the negative electrode current collector. The electrode substrate of the positive electrode plate is welded to the positive electrode current collector. Next, the electrode group is inserted into a metal outer can that also serves as a negative electrode terminal, the negative electrode current collector is welded to the bottom of the metal outer can, and the current collector lead portion extending from the positive electrode current collector is connected to the positive electrode terminal. After being welded to the bottom of the sealing body that also serves as the sealing member, an electrolytic solution is injected, and the sealing body is attached to the opening of the outer can through an insulating gasket and sealed.

  In recent years, nickel nickel foam has been used as a positive electrode substrate in order to further improve the energy density of these alkaline storage batteries. However, when a positive electrode using nickel foam as an electrode substrate is welded to the positive electrode current collector, it is difficult to weld this directly to the positive electrode current collector because the nickel foam is highly porous and has a low density. It was. For this reason, it is proposed in Patent Document 1 (Japanese Patent Laid-Open No. 11-149914) to weld a ribbon-like tab to the end of the foamed nickel and weld this tab to the positive electrode current collector. It was.

However, welding a ribbon-shaped tab to the end of foamed nickel requires a ribbon-shaped tab separately from the foamed nickel, which increases the number of parts and further requires a welding process, so this type of positive electrode is expensive. The problem of becoming. Therefore, in order to weld the current collector directly to the electrode substrate made of nickel foam, the present inventors have made various studies. As a result, for example, using a current collector provided with a substantially V-shaped groove proposed in Patent Document 2 (JP-A-60-72160), for example, Patent Document 3 (JP-A 56-56). When the welding method proposed in JP-A-67166 is applied, it was found that the current collector can be directly welded to the electrode substrate made of foamed nickel.
Japanese Patent Laid-Open No. 11-149914 JP-A-60-72160 JP-A-56-67166

  However, when the current collector is directly welded to the electrode substrate made of foamed nickel by combining the techniques proposed in Patent Documents 2 and 3 described above, the welded portion between the electrode substrate and the current collector is used. There was a problem that sufficient strength could not be obtained. Here, if the welded portion between the electrode substrate and the current collector is welded without obtaining sufficient strength, the electrical resistance at the welded portion increases, increasing the internal resistance value as a battery, The problem was that the output characteristics could not be obtained. In addition, there is a possibility that the current collector may come off due to vibration or the like, and there is a problem that good current collection cannot be maintained.

  Accordingly, the present invention has been made to solve the above-described problems, and even when a current collector is directly welded to an electrode substrate made of foamed nickel, these welds can obtain sufficient strength. Thus, it is an object of the present invention to provide a battery in which the electrical resistance at the welded portion is reduced and the internal resistance is reduced and high output characteristics can be obtained.

In the alkaline storage battery of the present invention, an electrode group formed by spirally winding a positive electrode and a negative electrode arranged to face each other via a separator is accommodated in an outer can together with an alkaline electrolyte. The opening is sealed with a sealing body. And at least one electrode substrate of the positive electrode and the negative electrode of the electrode group is foamed nickel, and a plate-like current collector is welded to the end of the electrode substrate, and between the positive electrode and the negative electrode of the electrode group An end portion of the separator disposed in the portion extends to the position of the current collector, and the end portion is welded to the current collector.

Thus, the end of the separator disposed between the positive electrode and the negative electrode of the electrode group extends to the position of the current collector welded to the end of one electrode substrate of the electrode group. When the end of the electrode is welded to the current collector, in addition to the joining force by welding the end of the electrode substrate and the current collector, the joining force by welding the separator and the current collector is added. The bonding force between the electrode and the current collector increases. Thereby, even if it receives a vibration, the welding part of an electrical power collector becomes difficult to remove | deviate, and favorable electrical power collection property will be maintained.

  Hereinafter, an embodiment in which the present invention is applied to a nickel-cadmium storage battery will be described with reference to FIGS. 1 to 3, but the present invention is not limited to this and the scope does not change the gist thereof. And can be implemented with appropriate changes. 1 is a cross-sectional view schematically showing a nickel-cadmium storage battery of Example 1. FIG. FIG. 2 is a cross-sectional view schematically showing a nickel-cadmium storage battery of Comparative Example 1 (conventional example). FIG. 3 is a plan view schematically showing a state in which the positive electrode and the positive electrode current collector of the electrode group are welded.

1. Electrode (1) Nickel positive electrode plate First, a positive electrode active material slurry 11b (21b) comprising a positive electrode active material mainly composed of nickel hydroxide and a binder on a positive electrode substrate (electrode substrate) 11a (21a) made of foamed nickel. Filled. At this time, an active material unfilled portion 11c (21c) that is not filled with an active material is formed in a portion to be welded to the positive electrode current collector 15 later. Next, after drying, the sheet is rolled to a predetermined thickness (for example, 0.5 mm) and cut to have predetermined dimensions (for example, a length of 200 mm and a width of 33 mm). The nickel positive electrode plate 11 (21) as shown in FIG.

(2) Cadmium negative electrode plate Also, negative electrode active material slurry 12b (22b) composed of a negative electrode active material mainly composed of cadmium oxide and a binder is applied to both surfaces of a plate core 12a (22a) composed of punching metal. did. At this time, an active material uncoated portion 12c (22c) to which the active material is not applied is formed in a portion to be welded to the negative electrode current collector 14 later. Next, after drying, the sheet is rolled to a predetermined thickness (for example, 0.6 mm) and cut to have predetermined dimensions (for example, a length of 240 mm and a width of 33 mm). The cadmium negative electrode plate 12 (22) as shown in FIG.

2. Battery (1) Example 1
Next, a nylon separator (for example, a length of 550 mm and a width of 34 mm) 13 was overlapped between the obtained nickel positive electrode plate 11 and cadmium negative electrode plate 12. In this case, the upper end portion of the nickel positive electrode plate 11 and the upper end portion of the separator 13 were located at the same position, and the upper end portion of the cadmium negative electrode plate 12 was overlapped with each other. Subsequently, these were wound in a spiral shape to produce a spiral electrode group a1. In the spiral electrode group a1 thus manufactured, the active material unfilled portion 11c is exposed on the upper portion of the nickel positive electrode plate 11, as shown in FIG. The active material uncoated part 12c is exposed at the lower part.

  Next, the positive electrode current collector 15 was placed on the active material unfilled portion 11c of the nickel positive electrode plate 11 and the upper end portion of the separator 13 exposed at the upper end surface of the spiral electrode group a1 obtained. As a result, the upper end portion of the separator 13 comes into contact with the positive electrode current collector 15. As shown in FIG. 3, the positive electrode current collector 15 has a central opening 15b in the center of the substantially circular main body 15a and a lead having a substantially rectangular planar shape extending from the main body 15a. A portion 15c is formed.

  Next, as shown in FIG. 3, a pair of welding electrodes R1, R2 are mounted on the positive electrode current collector 15, respectively, and a first welding current is applied from the power source V between the pair of welding electrodes R1, R2. Washed away. Thereby, the positive electrode current collector 15 and the active material unfilled portion 11c of the nickel positive electrode 11 are resistance-welded. At this time, the positive electrode current collector 15 is heated by welding heat, so that the upper end portion of the separator 13 disposed so as to be in contact with the positive electrode current collector 15 is also heated. Thereafter, welding was similarly performed at 90 °, 180 °, and 270 ° from this welding position.

  As a result, the positive electrode current collector 15 is welded to the upper end surface of the spiral electrode group a1. At the same time, the upper end portion of the separator 13 disposed so as to be in contact with the positive electrode current collector 15 is welded to the positive electrode current collector 15. On the other hand, a disc-shaped negative electrode current collector 14 is placed under the spiral electrode group a1, and a pair of welding electrodes are similarly brought into contact with each other to apply the active material uncoated 12c of the cadmium negative electrode plate 12 and the negative electrode collector. The contact portion with the electric body 14 was resistance-welded to produce a spiral electrode body a.

  Next, after the electrode body a produced as described above was inserted into the outer can 16, the negative electrode current collector 14 and the bottom of the outer can 16 were welded. Further, a sealing body 17 composed of a positive electrode lid 17 a and a positive electrode cap 17 b was prepared, and a lead portion 15 c extending from the positive electrode current collector 15 was welded to the bottom of the positive electrode lid 17 a provided on the sealing body 17. Thereafter, the upper outer peripheral surface of the outer can 16 was grooved to form the annular groove 16a. Thereafter, an electrolytic solution (for example, 30 mass% potassium hydroxide (KOH) aqueous solution) is injected into the metal outer can 16, and the sealing gasket 18 attached to the outer peripheral portion of the sealing body 17 is attached to the outer can 16. The nickel-cadmium storage battery 10 (A) of Example 1 was assembled by placing it on the annular groove 16 a and caulking and sealing the tip 16 b of the outer can 16 toward the sealing body 17.

(2) Comparative Example 1
In the same manner as described above, a nylon separator (for example, a length of 550 mm and a width of 33 mm) 23 was overlapped between the nickel positive electrode plate 21 and the cadmium negative electrode plate 22. In this case, the separator 23 was overlaid so that the upper end portion of the separator 23 was located below the upper end portion of the nickel positive electrode plate 21 and the upper end portion of the cadmium negative electrode plate 22 was located below the upper end portion of the separator 23. Subsequently, these were wound in a spiral shape to produce a spiral electrode group x1. In the spiral electrode group x1 produced in this way, as shown in FIG. 2, the active material unfilled portion 21c is exposed on the upper portion of the nickel positive electrode plate 21, and the cadmium negative electrode plate 22 The active material uncoated part 22c is exposed at the lower part.

  Subsequently, the positive electrode current collector 15 described above was placed on the upper end portion of the active material unfilled portion 21c of the nickel positive electrode plate 21 exposed at the upper end surface of the spiral electrode group x1 obtained. Next, as shown in FIG. 3, a pair of welding electrodes R1 and R2 were placed on the positive electrode current collector 15, and a welding current was passed. Thereby, the positive electrode current collector 15 and the active material unfilled portion 21c of the nickel positive electrode 21 are resistance-welded. Thereafter, welding was similarly performed at 90 °, 180 °, and 270 ° from this welding position. As a result, the positive electrode current collector 15 is welded to the upper end surface of the spiral electrode group x1. On the other hand, a disc-shaped negative electrode current collector 14 is placed below the spiral electrode group, and a pair of welding electrodes are similarly brought into contact with each other to prevent the active material uncoated portion 22c of the cadmium negative electrode plate 22 and the negative electrode current collector. The contact portion with the electric body 14 was resistance-welded to produce a spiral electrode body x.

  Next, after the electrode body x produced as described above was inserted into the outer can 26, the negative electrode current collector 24 and the bottom of the outer can 26 were welded. Further, a sealing body 27 composed of a positive electrode lid 27 a and a positive electrode cap 27 b was prepared, and a lead portion 15 c extending from the positive electrode current collector 15 was welded to the bottom of the positive electrode lid 27 a provided on the sealing body 27. Thereafter, the upper outer peripheral surface of the outer can 26 was grooved to form an annular groove 26a. Thereafter, an electrolytic solution (for example, 30 mass% potassium hydroxide (KOH) aqueous solution) is injected into the metal outer can 26, and the sealing gasket 28 attached to the outer periphery of the sealing body 27 is attached to the outer can 26. The nickel-cadmium storage battery 20 (X) of Comparative Example 1 was assembled by placing on the annular groove 26 a and caulking and sealing the tip 26 b of the outer can 26 to the sealing body 27 side.

3. Test (1) Strength Test Next, when each battery A, X is manufactured as described above, 10 electrode bodies a, x are respectively manufactured, and the welding strength of the positive electrode current collector 15 after welding is measured. The relative strength was measured when the value of the electrode body x was 100. As a result, the relative strength of the electrode body x is 100, whereas the relative strength of the electrode body a is 250, indicating that the welding strength is improved by 2.5 times the strength of the electrode body x. It was. This is because in the electrode body a, the upper end portion of the separator 13 disposed so as to be in contact with the positive electrode current collector 15 is welded to the positive electrode current collector 15, thereby improving the bonding strength.

(2) Vibration Test Next, a vibration test was performed using 10 batteries A and X produced as described above, and the change in internal resistance before and after the vibration test was determined. In this case, a vibration test machine (VC-081DAFX32PSR manufactured by Emic Co., Ltd.) was prepared, and five batteries A and X were arranged in this vibration test machine, respectively, and a vibration test was performed. Specifically, the maximum acceleration was 30 G, the frequency was 17 Hz, the amplitude was 5 mm, and the vibration time was set to 10 hours. When the internal resistance before and after the vibration test was measured, the results shown in Table 1 below were obtained.

 As is clear from the results of Table 1 above, in battery A, the change in internal resistance before and after the vibration test is 0.1 mΩ, whereas in battery X, the internal resistance before and after the vibration test. The change of is 7.6 mΩ, and it can be seen that the internal resistance is increased more than double that before the vibration test. In the battery X, it is considered that a part of the welded portion between the positive electrode current collector 15 and the active material unfilled portion 21c of the nickel positive electrode 21 is removed by the vibration test and the internal resistance is increased.

  On the other hand, in the battery A, the upper end portion of the separator 13 disposed so as to be in contact with the positive electrode current collector 15 is welded to the positive electrode current collector 15. For this reason, since the joint strength at the welded portion between the positive electrode current collector 15 and the active material unfilled portion 11c of the nickel positive electrode 11 is large, it does not come off by the vibration test. As a result, it is considered that the internal resistance did not increase regardless of the vibration test.

  As described in detail above, in the present invention, the current collector 15 in which the end portion of the separator 13 disposed between the positive electrode 11 and the negative electrode 12 of the electrode group a1 is welded to the upper end portion of the electrode group a1. Since the end of the separator 15 is welded to the current collector 15, the coupling force between the electrode group a1 and the current collector 15 is increased. Thereby, even if it gives a vibration, the electrical power collector 15 will not remove | deviate from the electrode group a1, but favorable electrical power collection property will be maintained.

  In the above-described embodiment, the example in which the present invention is applied to a nickel-cadmium storage battery has been described. However, the present invention is not limited to a nickel-cadmium storage battery, but an alkaline storage battery such as a nickel-hydrogen storage battery, a lithium ion battery, or the like. It is clear that the same effect can be obtained even when applied to the above battery.

It is sectional drawing which shows typically the nickel-cadmium storage battery of the Example of this invention. It is sectional drawing which shows typically the nickel-cadmium storage battery of a comparative example. It is a top view which shows typically the state which welds the positive electrode and positive electrode electrical power collector of an electrode group.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Nickel-cadmium storage battery, 11 ... Nickel positive electrode plate, 11a ... Positive electrode core, 11b ... Positive electrode active material, 11c ... Active material unfilled part, 12 ... Cadmium negative electrode plate, 12a ... Electrode plate core, 12b ... Negative electrode active Substance, 12c ... Active material uncoated part, 13 ... Separator, 14 ... Negative electrode current collector, 15 ... Positive electrode current collector, 15a ... Main body part, 15b ... Center opening, 15c ... Lead part, 16 ... Exterior can, 16a ... annular groove part, 16b ... tip part, 17 ... sealing body, 17a ... positive electrode lid, 17b ... positive electrode cap, 18 ... sealing gasket

Claims (2)

A group of electrodes formed by spirally winding a positive electrode and a negative electrode, which are arranged to face each other via a separator, are accommodated in an outer can together with an electrolyte, and the opening of the outer can is sealed with a sealing body. Batteries,
At least one electrode substrate of the positive electrode and the negative electrode of the electrode group is foamed nickel, and a plate-like current collector is welded to an end of the electrode substrate ,
A battery, wherein an end of a separator disposed between a positive electrode and a negative electrode of the electrode group extends to a position of the current collector, and the end is welded to the current collector.   The battery according to claim 1, wherein the current collector is a positive electrode current collector, and the positive electrode current collector is welded to an upper end portion of the electrode group.

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