JPH05190199A - Cylindrical secondary battery - Google Patents

Abstract

PURPOSE:To provide a cylindrical secondary battery which surely prevents the leak of liquid caused by a positive electrode lead and the internal short circuit due to the contact between a positive electrode lead and a negative electrode plate. CONSTITUTION:An electrode group 5 is constituted of a positive electrode plate 1 having a lead 2 for collecting electricity, negative electrode plate 6 and a separator 7 which is interposed between these electrode plates and wound in swirl form. The positive electrode lead 2 is welded on a sealing port plate 10 formed integrally with a positive electrode cap 11, and a reinforcing rib 3 is installed in the upper part, and an insulating cover 4 is installed in the lower part from the upper edge of the electrode group 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical secondary battery.

[0002]

2. Description of the Related Art Conventionally, in a cylindrical secondary battery using a positive electrode plate with a lead, short circuit due to contact between the positive electrode lead and the negative electrode plate or between the positive electrode lead and an outer case is prevented, and the strength of the positive electrode lead is improved. Therefore, most of the positive electrode lead except the tip and the lead mounting portion of the positive electrode plate have been covered with an insulating tape.

However, in such a structure, the distance between the positive electrode lead and the valve opening portion of the sealing plate is short, and the electrolytic solution adheres to the portion directly below the valve opening due to surface tension at the time of charging, and the electrolytic solution acts as a safety valve. Since it goes out together with the gas at the time of operation, it has a drawback of leaking liquid. Therefore, in order to suppress the adhesion due to the surface tension of the electrolytic solution, it is conceivable to shorten the coating of the insulating tape, but this reduces the strength of the positive electrode lead and increases the bending and twisting of the positive electrode lead. Defects in the spot welding process of the lead and the sealing plate increase. Moreover, since the metal surface of the positive electrode lead is exposed over most of the area, an internal short circuit easily occurs due to the contact between the positive electrode lead and the negative electrode plate or the contact between the positive electrode lead and the outer case. In order to prevent these drawbacks, it is most effective to shorten the length of the lead itself, but this has a drawback that assembly becomes difficult.

[0004]

The problem with the prior art is that if the portion of the insulating tape that covers the positive electrode lead is long, the surface tension of the electrolyte tends to cause liquid leakage, and if the portion is short, the strength of the positive electrode lead is low. It was low, there were many defects in the welded portion with the sealing plate, and the metal surface of the positive electrode lead was largely exposed, so that an internal short circuit was likely to occur.

The present invention solves the above-mentioned problems of the prior art, and has a cylindrical secondary battery having a positive electrode lead that causes little leakage of electrolyte, has a large strength of itself, and has less risk of internal short circuit. It is intended to provide.

[0006]

In order to achieve the above object, the present invention has an electrode group in which a positive electrode plate, a negative electrode plate and a separator interposed between these electrode plates are spirally wound. , The upper end is welded to the sealing plate integrated with the positive electrode cap, and the lower end is fixed to the positive electrode.The positive electrode lead has a reinforcing rib on the upper part, and an insulating coating is applied to the lower part below the upper end of the electrode group. Is what

[0007]

In such a cylindrical secondary battery, by shortening the insulating coating portion by the insulating tape, the electrolytic solution does not adhere to the portion directly below the valve opening due to the surface tension, and the leakage resistance is improved. There are two effects of preventing an internal short circuit caused by the protrusion of the negative electrode plate penetrating the separator.
Further, by attaching the reinforcing rib to the portion not covered with the insulating coating, the strength of the positive electrode lead is improved, and no defect occurs in the spot welding process of the positive electrode lead and the sealing plate. And since the positive electrode lead always bends at the base of the reinforcing rib,
The bending position is constant. As a result, short circuit due to contact between the positive electrode lead and the outer case and between the positive electrode lead and the upper portion of the negative electrode plate can be prevented. Furthermore, since it is possible to make a gap between the positive electrode lead and the valve opening of the sealing plate, there is an effect that the liquid leakage resistance is improved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a positive electrode plate, and a positive electrode lead 2 thereof is provided with a reinforcing rib 3 for improving strength and an insulating coating 4 made of an insulating tape. 5 is a positive electrode plate 1 and a negative electrode plate 6
And an electrode group composed of a separator 7 interposed between these electrode plates, on which an insulating ring 8 is installed. After the electrode group 5 is grooved in the battery outer case 9, the tip of the positive electrode lead 2 is welded to the back surface of the sealing plate 10, and the battery outer case 9 is closed by the sealing plate 10. 1
Reference numeral 1 is a positive electrode cap integrated with the sealing plate 10. 12 is an insulating plate installed on the electrode group 5, and 13 is a valve port.

An example in which such a lead structure for a positive electrode plate is applied to a nickel-cadmium storage battery will be described below. The annealed positive electrode lead 2 for current collection having a width of 3 mm and a length of 22 mm is welded to the positive electrode plate 1 made of an active material containing nickel hydroxide as a main component shown in FIG. A reinforcing rib 3 having a depth of 0.5 mm is applied from a position of 3 mm to a width of 1 mm and a length of 7 mm, and further, a width of 6 mm,
The insulating coating 4 made of polypropylene insulating tape having a length of 12 mm was prepared by adhering the insulating coating 4 on both surfaces so that the portion without the tape coating had a length of 10 mm. The positive electrode plate 1 thus prepared, the paste type negative electrode plate 6 made of an active material containing cadmium oxide as a main component, and a 6.6 nylon separator 7 inserted between these electrode plates are spirally wound. It was wound into a shape and housed in the battery outer case 9. The reinforcing ribs 3 of the positive electrode lead 2 are arranged so that the convex portions of the reinforcing ribs 3 of the positive electrode lead 2 and the valve opening 13 of the sealing plate 10 are opposed to each other, and the width thereof is 1/2 or less of the diameter of the sealing plate. Is desirable. Also, a plurality of reinforcing ribs 3 may be provided. Then, the positive electrode lead 2 and the back surface of the sealing plate 10 were welded. The results of evaluating the defect rate in the process are shown in (Table 1).

[0011]

[Table 1]

Next, an aqueous potassium hydroxide solution having a concentration of 15% by weight was added to prepare an A size nickel cadmium storage battery having a nominal capacity of 1400 mAh. The results of evaluating the liquid leakage of the obtained battery with a CR test paper when it was charged at 2 CmA for 1 hour in an atmosphere of 0 ° C are shown in (Table 1). As is clear from (Table 1), there were no defects during assembly and the liquid leakage resistance was excellent. An insulating plate 12 made of polyvinyl chloride having a diameter of 16 mm, a width of 8 mm, a thickness of 0.4 mm, and a diameter of the central liquid injection hole of 2 mm was placed on the electrode group 5, and further, a diameter of 16 mm was provided thereon. , Thickness 0.4m
When the insulating ring 8 made of polyvinyl chloride and having a diameter of the central through hole of 12 mm is installed at m, the electrode group 5 and the positive electrode lead 2 are completely separated, so that the insulating plate 12 and the insulating ring 8, The reliability is further improved by combining the reinforcing ribs 3 with each other.

In Comparative Example 1, instead of the positive electrode lead of the example, 4 m from the tip of the positive electrode lead 22 as shown in FIG.
It was prepared in the same manner as in the example except that the insulation coating 24 made of polypropylene insulating tape having a width of 6 mm and a length of 23 mm from both sides of m was attached to both sides, and ribs were omitted. The results of evaluation of the number and liquid leakage are shown in (Table 1). In addition, 21 shows a positive electrode. Comparative Example 2 was prepared in the same manner as in Example 1 except that the rib was omitted and the tape was shortened as shown in FIG. That is, in FIG. 3, 31 is a positive electrode, 32 is a positive electrode lead, and 34.
Is an insulating coating with an insulating tape, 35 is an electrode group composed of the positive electrode plate 31, the negative electrode plate 36, and the separator 37, 40 is a sealing plate integrated with the positive electrode cap 41 and has a valve opening 42, and 39 is a battery outer case .. Then, the results of evaluating the number of defects and liquid leakage during battery assembly are shown in (Table 1).
As is clear from Table 1, it is clearly understood that Comparative Example 1 is inferior to the Examples of the present invention in terms of liquid leakage and internal short circuit, and Comparative Example 2 in terms of defective rate and internal short circuit during assembly. did it.

[0014]

As is apparent from the above description of the embodiments, in the cylindrical secondary battery of the present invention, the length of the insulating coating by the insulating tape of the positive electrode lead is shortened and the uncoated portion is reinforced. By providing the rib, it is possible to reliably prevent liquid leakage due to the positive electrode lead, and internal short circuit due to contact between the positive electrode lead and the negative electrode plate and between the positive electrode lead and the outer case.

[Brief description of drawings]

FIG. 1A is a plan view of a positive electrode plate according to an embodiment of the present invention. FIG. 1B is a longitudinal sectional view of a cylindrical secondary battery according to an embodiment of the present invention.

FIG. 2 is a plan view of a conventionally used positive electrode plate of Comparative Example 1.

FIG. 3 is a vertical cross-sectional view of a conventional cylindrical secondary battery of Comparative Example 2.

[Explanation of symbols]

 1, 21, 31 Positive electrode plate 2, 22, 32 Positive electrode lead 3 Reinforcing rib 4, 24, 34 Insulating coating 5, 35 Electrode group 6, 36 Negative electrode plate 7, 37 Separator 8 Insulating ring 9, 39 Battery outer case 10, 40 Sealing plate 11, 41 Positive electrode cap 12 Insulation plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motohide Masui 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A cylindrical two-body structure in which an electrode group formed by spirally winding a positive electrode plate, a negative electrode plate, and a separator between them is loaded in a battery outer case and sealed with a sealing plate having a valve port. In the secondary battery, the lower end is fixed to the positive electrode plate, the upper end is welded to the sealing plate, a reinforcing rib is provided on the upper part of the positive electrode lead, and a cylindrical secondary having an insulating coating on the lower part located below the upper end of the electrode group. battery. 2. A cylindrical secondary battery in which an insulating plate for preventing contact between a positive electrode lead and a negative electrode of the electrode group is provided on the electrode group according to claim 1.