JP2001256935A - Sealed-type alkali storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed-type alkali storage battery with superior property of high-rate charge and discharge by depositing positive pole cap and sealing plate more reliably to cut down internal resistance of the battery. SOLUTION: The sealed-type alkali storage battery is accommodated in an interior of a battery armored can 30 of a bottomed cylinder shape, and equipped with a sealing plate 40 electrically connected to an electrode body 12 formed by interposing a separator 18 between a positive pole plate 14 and a negative pole plate 16, a safety valve unit 60 to close a degassing hole 42 provided on the sealing plate 40, and a sealing body 80 consisting of a positive pole cap 70 that accommodates the safety valve unit 60 between it and the sealing plate 40 in a compressed state. The sealing plate 40 is formed by means of a material with electroconductivity higher than the positive pole cap 70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a sealed body of a sealed alkaline storage battery.

[0002]

2. Description of the Related Art A sealed alkaline storage battery such as a nickel-cadmium storage battery or a nickel-hydride storage battery is a secondary battery using an aqueous alkaline solution as an electrolyte. As shown in FIG. 1, the alkaline storage battery (10) includes a negative electrode current collector (22), an electrode body (12), and a positive electrode current collector (20) in a bottomed cylindrical metal battery outer can (30). Is accommodated together with the electrolytic solution L, and the opening (32) of the outer can (30) is sealed with a sealing body (80). As shown in FIG. 1, the electrode body (12) includes a positive electrode plate (14) and a negative electrode plate (1).
6), a gas permeable separator (18) is interposed therebetween, and it is wound in a spiral shape. Positive electrode plate (14) and negative electrode plate (1
6) is formed by filling a conductive electrode plate with nickel oxide and a cadmium compound as active materials, respectively. Sealing body (80)
Has a vent hole (42) in the center and a positive electrode current collector (20)
Side sealing plate (40), a safety valve device (60) that closes the gas vent hole (42), and a positive electrode cap (50) housed between the sealing plate (40) with the safety valve device (60) compressed. 70).
The sealing plate (40) is connected to the outer can (30) via an insulating gasket (76).
Is crimped to the end of the opening (32) to seal the outer can (30). The negative electrode current collector (22) and the negative electrode plate (16) are electrically connected, and the positive electrode plate (14), the positive electrode current collector (20), the sealing plate (40), and the positive electrode cap (70) are also electrically connected. It is connected to the.

[0003] Conventionally, the sealing body (80) has been previously assembled before connection to the positive electrode current collector (20). As an example of a method for manufacturing the sealing body (80), as shown in FIG.
Safety valve device (60) between sealing plate (40) and positive electrode cap (70)
After being stored in a compressed state, the sealing plate (40) and the positive electrode cap (7
The electrode rods (50) and (50) are arranged on both sides of (0), and a current is applied to the electrode rods (50) and (50) to perform resistance welding between the sealing plate (40) and the positive electrode cap (70), thereby electrically There is a way to connect.

After assembling the sealing body (80), as shown in FIG. 7, a lead tab (82) formed on the positive electrode current collector (20) is welded to the sealing plate (40) to form a positive electrode current collector. After electrically connecting (20) and the sealing plate (40), the sealing body (80) was attached to the outer can (30) by bending the lead tab (82).

In recent years, in applications such as electric tools and electric vehicles,
Alkaline storage batteries are required to have high rate charge / discharge performance.
To increase the high-rate charge / discharge performance, it is necessary to reduce the internal resistance of the battery, and in particular, to reduce the electrical resistance at the positive-side electrical junction, which controls the current inside the battery during high-rate charging. Is valid.

[0006]

However, the lead tab (82) must be formed thin because it needs to be bent, and the lead tab (82) must be formed thinly in order to improve workability at the time of welding with the sealing plate (40). However, there is a problem that the electric resistance must be increased to some extent, and the electric resistance increases accordingly. Therefore, it is important to electrically connect the sealing plate (40) and the positive electrode current collector (20) without using the lead tab (82) in order to reduce the internal resistance of the battery.

Therefore, the inventors do not assemble the sealing body (80) in advance and attach it to the outer can (30), but first, as shown in FIG. 2, the electrode housed in the outer can (30). Only the sealing plate (40) is placed on the body (12), and the positive electrode current collector (20) and the sealing plate (40)
After the safety valve device (60) is attached to the sealing plate (40) so that the gas vent hole (42) is closed (see FIG. 3), the safety valve device (60) is closed with the positive electrode cap (70). Put on the sealing plate (40) so as to be sandwiched between them, and as shown in FIG.
Place a pair of electrode rods (50) (50) on the side of the electrode rod (50) (50)
A method for manufacturing a sealed alkaline storage battery (10) has been proposed in which an electric current is passed therebetween to perform resistance welding and electrically connect the sealing plate (40) and the positive electrode cap (70).

However, when resistance welding is performed from the side of the positive electrode cap (70), a large amount of reactive current flows through the positive electrode cap (70), and there is a possibility that welding cannot be performed sufficiently. If the state of welding between the positive electrode cap (70) and the sealing plate (40) is not good, the electrical resistance at that portion increases, causing an increase in the internal resistance of the battery.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sealed alkaline storage battery excellent in high rate charge / discharge characteristics by further securely welding a positive electrode cap and a sealing plate to further reduce the internal resistance of the battery. It is.

[0010]

In order to solve the above-mentioned problems, a sealed alkaline storage battery of the present invention is housed inside a bottomed cylindrical battery outer can (30), and comprises a positive electrode plate (14) and a negative electrode. Board (16)
A sealing plate (40) electrically connected to the electrode body (12) with a separator (18) interposed therebetween, and a gas vent hole (42) opened in the sealing plate (40) are closed. In a sealed alkaline storage battery having a sealing body (80) comprising a positive electrode cap (70) for accommodating the safety valve device (60) in a compressed state between the safety valve device (60) and the sealing plate (40), a sealing plate is provided. (40) with the positive electrode cap (70)
It is formed of a material having higher conductivity than that of the first embodiment.

The sealed alkaline storage battery (10) is an outer can.
The sealing plate (40) is placed on the electrode body (12) housed in the (30), the positive electrode current collector (20) and the sealing plate (40) are welded, and the safety valve device (60)
Is attached to the sealing plate (40) so that the gas vent hole (42) is closed, and then the positive electrode cap (70) is placed on the sealing plate (40) so that the safety valve device (60) is sandwiched between the positive electrode cap and the positive electrode cap. A pair of electrode rods (50) and (50) are arranged on the side of (70), resistance welding is performed by passing current between the electrode rods (50) and (50), and the sealing plate (40) and the positive electrode cap (70) Can be produced by electrically connecting

[0012]

According to the sealed alkaline storage battery (10) of the present invention, the conductivity of the sealing plate (40) is made higher than the conductivity of the positive electrode cap (70). For this reason, when the electrode rods (50) and (50) are arranged on the side of the positive electrode cap (70) and resistance welding is performed, the welding current is lower than that of the positive electrode cap (70) having a large resistance but a small resistance. A lot flows into the sealing plate (40). Therefore,
Reactive current flowing through the positive electrode cap (70) can be reduced, and a large amount of welding current flows at the junction between the positive electrode cap (70) and the sealing plate (40), ensuring reliable welding and improving welding strength. it can.

By improving the welding strength between the positive electrode cap (70) and the sealing plate (40), the electric resistance between the positive electrode cap (70) and the sealing plate (40) decreases. In addition, the sealed alkaline storage battery (10) of the present invention does not require a lead tab, which has conventionally caused an increase in the internal resistance of the battery.Therefore, the synergistic effects of these can further reduce the internal resistance of the battery. ,
Battery performance such as high-rate charge / discharge characteristics of the battery can be improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be suitably applied to a sealed alkaline storage battery such as a nickel-cadmium storage battery or a nickel-hydride storage battery.

FIG. 1 is a longitudinal sectional view of a storage battery (10) manufactured by the method of the first embodiment, and FIGS.
FIG. 4 is an explanatory view showing a method for producing the battery of FIG. The electrode body (12)
Positive electrode active material on core of conductive electrode plate such as punching metal,
It is manufactured by spirally winding a positive electrode plate (14) and a negative electrode plate (16) each filled with a negative electrode active material with a gas-permeable separator (18) interposed therebetween (see FIG. 1). A part (14a) of the electrode plate of the positive electrode plate (14) is exposed from the upper end of the electrode body (12), and the electrode body (1) is exposed.
A part of the electrode plate (14b) of the negative electrode plate (16) is exposed from the lower end of 2).

A positive electrode current collector (20) is provided on the upper end surface of the electrode body (12).
Are provided, and the electrode plate exposed portion (14) of the positive electrode plate (14) is
It is electrically connected to a). A negative electrode current collector (22) is provided on the lower end surface of the electrode body (12), and is similarly electrically connected to the electrode plate exposed portion (14b) of the negative electrode plate (16) by welding or the like.

The electrode body (12) to which the current collectors (20) and (22) are connected,
The negative electrode current collector (22) is on the bottom (34) side, and the positive electrode current collector (20) is open (3
2) It is housed in a bottomed cylindrical battery outer can (30) so as to be on the side. After storing the electrode assembly (12) in the outer can (30), the outer can (3
A welding electrode is arranged on the bottom surface (34) of the (0), and an elongated welding electrode rod is inserted into the center of the electrode body (12) to contact the negative electrode current collector (22). An electric current is applied, and the bottom surface (34) of the outer can (30) and the negative electrode current collector (22) are welded and electrically connected.

Next, a sealing plate (40) is placed on the positive electrode current collector (20), and these are electrically connected. The sealing plate (40)
It is made of a material having higher conductivity than a positive electrode cap (70) described later, and has a concave portion (44) in which a gas vent hole (42) is opened in the center as shown in FIG. On the outer periphery of 44), a step (46) into which the positive electrode cap (70) fits, and the step (46)
An edge (48) of the outer can (30) is formed on the outer periphery of the outer can (30). In addition, desirable materials for forming the sealing plate (40) will be described in detail at the end of the embodiment. Sealing plate (4
0) is placed on the positive electrode current collector (20), and the concave portion (4) of the sealing plate (40) is placed.
4) is brought into contact with the positive electrode current collector (20), and as shown in FIG.
The pair of electrode rods (50) and (50) are arranged above the concave portion (44) of the sealing plate (40), and a current is applied to the electrode rods (50) and (50), whereby the concave portion ( 44) and the positive electrode current collector (20) are resistance welded,
Electrically connected. Welding is performed at a plurality of locations.

After welding the sealing plate (40) and the positive electrode current collector (20), the electrolyte L is injected into the outer can (30) through the gas vent hole (42) of the sealing plate (40). . As the electrolytic solution, a potassium hydroxide (KOH) aqueous solution can be exemplified.

After the electrolyte solution L is injected into the outer can (30), a safety valve device (60) is attached to the concave portion (44) of the sealing plate (40). The safety valve device (60) includes a sealing plate (40) and a positive electrode cap (70) described later.
And a valve device that is disposed in a compressed state between and closes the gas vent hole (42), such as a rubber valve plate (62) as shown in FIG.
One that includes a valve plate and a spring can be exemplified.

After the safety valve device (60) is accommodated in the concave portion (44) of the sealing plate (40), the positive electrode cap (70) is covered, and the sealing plate (40) and the positive electrode cap (70) are welded. The positive electrode cap (70)
It is made of a material having lower conductivity than the sealing plate (40).
As shown in the figure, the center projects upward, and the convex portion (7
An edge (74) that fits into the step (46) of the sealing plate (40) is formed on the outer periphery of (2). In addition, desirable materials for forming the positive electrode cap (70) will be described in detail at the end of the embodiment. While compressing the safety valve device (60) on the inner surface of the convex portion (72) of the positive electrode cap (70), the edge portion (74) is fitted to the step (46) of the sealing plate (40), and FIG. As shown in FIG. 5, a pair of electrode rods (50) and (50) is arranged above the edge (74), and resistance welding is performed by flowing a current between the electrode rods (50) and (50). The welding current is passed from one electrode rod (50) through the positive electrode cap (70) to the sealing plate.
(40), pass through the sealing plate (40), and again
0) and flows to the other electrode rod (50). With this welding current, the positive electrode cap (70) and the sealing plate (40) are welded and electrically connected. It is desirable that the electrode rods (50) and (50) are not arranged close to each other, but are arranged so that the distance between the electrode rods (50) and (50) is as large as possible. Most preferably, as shown in FIG. 5, the electrode rods (50) (50) are arranged on the diameter of the positive electrode cap (70). By disposing the electrode rods (50) and (50) apart, the welding current flows more to the sealing plate (40) rather than to the positive electrode cap (70) having high electric resistance, so that the generation of reactive current can be suppressed. It is. Further, it is desirable that the resistance welding be performed at a plurality of locations on the edge portion (74) of the positive electrode cap (70). By increasing the number of joints,
Not only is the welding strength increased, but also the conductivity between the positive electrode cap (70) and the sealing plate (40) can be increased, and the electric resistance can be reduced.

After attaching the positive electrode cap (70) to the sealing plate (40), an insulating gasket (76) is attached to the outer periphery of the sealing plate (40), and the end of the opening (32) of the outer can (30) is bent. By sealing the sealing plate (40), the sealed alkaline storage battery (10) shown in FIG. 1 is manufactured.

In the above embodiment, the sealing plate (40) is welded after the electrode body (12) is housed in the outer can (30). However, the positive electrode current collector (20) of the electrode body (12) is ), The sealing plate (40) may be welded and then housed in the outer can (30). By performing welding before housing in the outer can (30), the welding state between the positive electrode current collector (20) and the sealing plate (40) can be easily confirmed visually.

In the above embodiment, the positive electrode current collector (20) is interposed between the electrode body (12) and the sealing body (80).
The positive electrode plate (14) and the sealing body (80) can be directly connected. In this case, the formation of the positive electrode current collector (20) can be omitted.

<< Desirable Materials >> Materials for the sealing plate (40) and the positive electrode cap (70) are selected such that the conductivity of the sealing plate (40) is higher than that of the positive electrode cap (70). conventionally,
For example, the sealing plate (40) and the positive electrode cap (70) were both made of Ni-plated Fe. In this case, the material of the positive electrode cap (70) was not changed, and the material of the sealing plate (40) was changed to N.
By using i or Ni-containing Fe, the conductivity of the sealing plate (40) can be increased. In addition, if the combination of the conductivity of the sealing plate (40) is higher than the conductivity of the positive electrode cap (70), a material is selected from Fe, Ni, Al, Cu, Zn, and alloys thereof. can do.

[0026]

EXAMPLE A nickel-cadmium storage battery (inventive example) in which a sealing plate (40) is made of a material having higher conductivity than the positive electrode cap (70) (see Table 1), a sealing plate (40) and a positive electrode cap (70). ) Were manufactured from the same material, and 20 nickel-cadmium storage batteries (comparative examples) were produced, and the welding strengths were compared. The welding between the sealing plate (40) and the positive electrode cap (70) was carried out by applying a voltage between the electrode rods or between the welding electrodes and applying an electric current of 8 kA for 20 msec.

The welding strength was measured by a tensile tester and is shown as a ratio with the comparative example being 100%. Sealing plate
Table 1 shows the materials using the measurement results of (40) and the positive electrode cap (70).

[0028]

[Table 1]

Referring to Table 1, it can be seen that the inventive example has higher welding strength than the comparative example. This is because, in the invention example, the conductivity of the sealing plate (40) was made higher than the conductivity of the positive electrode cap (70), so that the resistance of the positive electrode cap (7
This is because the reactive current flowing through 0) can be reduced, the welding current can be increased, and a good welding connection state can be obtained. on the other hand,
In the comparative example, since the sealing plate (40) and the positive electrode cap (70) are made of the same material, a large amount of reactive current flows toward the positive electrode cap (70), and the sealing plate (40) and the positive electrode cap (70) As a result, a sufficient welding current did not flow through the joint with (), and it was found that sufficient welding strength could not be obtained. The invention examples increase the welding strength between the positive electrode cap (70) and the sealing plate (40) as compared with the comparative example, and can secure a favorable welding state, so that the positive electrode cap (70) and the sealing plate (40) Can be reduced, and as a result, the internal resistance of the battery can be further reduced.

The description of the above embodiments is for the purpose of illustrating the present invention, and should not be construed as limiting the invention described in the appended claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a sealed alkaline storage battery of the present invention.

FIG. 2 is an explanatory view illustrating a method for manufacturing a battery of the present invention.

FIG. 3 is an explanatory view showing a method for producing a battery of the present invention.

FIG. 4 is an explanatory view showing a method for producing a battery of the present invention.

FIG. 5 is an explanatory diagram showing an arrangement of electrode rods at the time of resistance welding between a positive electrode cap and a sealing plate.

FIG. 6 is an explanatory view showing a conventional method for manufacturing a sealing body.

FIG. 7 is a cross-sectional view of a conventional sealed alkaline storage battery in which a positive electrode current collector and a sealing body are connected using a lead tab.

[Explanation of symbols]

 (10) Sealed alkaline storage battery (20) Positive electrode current collector (40) Sealing plate (50) Electrode rod (60) Safety valve device (70) Positive electrode cap (80) Sealing body

Continued on the front page F-term (reference)

Claims (3)

[Claims] 1. A separator (18) housed inside a bottomed cylindrical battery outer can (30) and disposed between a positive electrode plate (14) and a negative electrode plate (16).
A sealing plate (40) electrically connected to the electrode body (12) interposed therebetween, a safety valve device (60) for closing a gas vent hole (42) opened in the sealing plate (40), In a sealed alkaline storage battery comprising a sealing body (80) consisting of a positive electrode cap (70) for accommodating a safety valve device (60) in a compressed state with the plate (40), the sealing plate (40) has a positive electrode cap ( A sealed alkaline storage battery characterized by being formed of a material having higher conductivity than that of (70). 2. The sealing body (80) includes a sealing plate (40) and a positive electrode plate (14).
After electrically connecting the safety valve device (60) to the sealing plate (40), the positive valve cap (70) is attached to the sealing plate (40) so that the safety valve device (60) is sandwiched therebetween. , Positive electrode cap (7
2. The sealed alkaline storage battery according to claim 1, wherein the sealed alkaline storage battery is manufactured by performing resistance welding from the 0) side. A positive electrode current collector (20) is provided between the sealing plate (40) and the positive electrode plate (14), and the sealing plate (40) is connected to the positive electrode current collector (2).
The sealed alkaline storage battery according to claim 2, wherein the sealed alkaline storage battery is electrically connected to the positive electrode plate (14) via the positive electrode (0).