JPH064535Y2 - Electrode plate for alkaline storage battery - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial field of application The present invention relates to an electrode plate for an alkaline storage battery using a three-dimensional porous body such as a foam metal or a metal fiber sintered body, and in particular, a tab for collecting current. It is related to the mounting structure of.

(B) Conventional Technique An electrode plate used in an alkaline storage battery is generally formed by using an active material holder filled with an active material as an electrode plate and resistance-welding a current collecting tab to the electrode plate.

By the way, a sintered nickel substrate is generally employed as the active material holder, and an electrode plate is manufactured by filling the active material by the chemical impregnation method using the sintered nickel substrate. The sintered nickel electrode plate produced by such a method exhibits excellent characteristics in many aspects such as discharge characteristics and cycle characteristics, but its manufacturing method is complicated,
Further, there is a drawback that it takes a long time to manufacture it.

On the other hand, in order to solve such a drawback, an electrode plate has been proposed in which an active material holder made of a three-dimensional porous body such as a foam metal or a metal fiber sintered body is directly filled with the active material. (See, for example, JP-A-56-145668). The metal fiber sintered body is a three-dimensional porous body having a fiber diameter of 5 to 50 μm, a pore diameter of 2 to 20 μm, and a porosity of 90 to 95%, and the powdered active material can be directly filled inside the electrode plate. The manufacturing process can be simplified, and the time required for the manufacturing can be shortened.

The active material holder constituting the electrode plate is a three-dimensional porous body, because its metal density is low, in the case of producing an alkaline storage battery welding electrode plate by resistance welding a current collecting tab on the surface,
Since the area of the welded portion was extremely small, the adhesive strength and the current collecting property at the welded portion of the obtained electrode plate and the current collecting tab were insufficient.

Further, when nickel hydroxide, which is an active material, adheres to the welded portion, there are many problems such as tab failure due to detonation due to explosion or welding fatigue of the porous body during resistance welding.

In order to solve such a problem, Jitsuko Sho 63-517
Japanese Patent Laid-Open Publication No. 6-68242 discloses that a reinforcing member welded so as to sandwich the current collecting tab mounting portion has an opening through which the current collecting tab penetrates, thereby strengthening the mounting of the current collecting tab. ing. When a nickel plate is used as the reinforcing member used here and the electrode plate is wound to form a spirally wound electrode body, the nickel plate has no flexibility, and the edge portion sticks to the separator and causes an internal short circuit. Further, when a heat-fusible resin plate is used as the reinforcing member, since the resin plate does not have conductivity, it is not possible to expect an increase in current collection efficiency.

(C) Problems to be Solved by the Invention The present invention has been made in view of the above problems, and a three-dimensional porous body such as a foam metal or a metal fiber sintered body is used as an electrode substrate to collect a current collecting tab. When the is attached, the mounting strength of the current collecting tab is increased and the current collecting efficiency is improved.

(D) Means for Solving the ProblemsThe electrode plate for an alkaline storage battery of the present invention is a plate in which a three-dimensional porous body is filled with an active material, a collector tab welded to the plate, and the electrode. And a conductive tape covering at least one entire surface of the current collecting tab on the plate, the conductive tape,
It is in contact with the current collecting tab and the electrode plate and welded together with the current collecting tab on the electrode plate.

Further, it is preferable that the conductive tape is an alkali resistant metal foil.

(E) Action With the configuration of the present invention, the fixing strength of the current collecting tab to the three-dimensional porous body can be increased. Further, since the current collecting tab is covered with the conductive tape and welded together with the current collecting tab on the electrode plate so as to be in contact with the electrode plate, it is possible to improve the current collecting efficiency. Further, the conductive tape has higher flexibility than a nickel plate, and even if the spirally wound electrode body is configured, there is no fear that the conductive tape will stick to the separator or blow.

(C) Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(Example 1) FIG. 1 is a front view showing an example of an electrode plate for an alkaline storage battery according to the present invention, and FIG. 2 is a vertical cross-sectional view of the electrode plate shown in FIG. 1 shows an electrode plate in which an active material holder, which is a body, is filled with an active material. The electrode plate 1 is formed by filling a nickel fiber felt-like sintered body (metal fiber sintered body) with paste-form nickel hydroxide as a main active material,
After adding a binder, after performing each treatment of drying and compression molding,
It is cut into a predetermined shape. The active material is removed from the welded portion 1a of the current collecting tab of the electrode plate 1.

The current collecting tab 2 is placed on the welded portion 1a of the electrode plate 1, and the conductive tape 3 made of nickel foil and having a thickness of 70 μm is used.
b is bonded from the opposite surface on which the current collecting tab is placed to fix the current collecting tab, and resistance welding is performed. In addition, 4 in a figure shows a spot welding point. Then, the conductive tape 3a is attached from the side on which the conductive tab facing the tape is placed, and resistance welding is performed again. Here, since the adhesive of the conductive tape has a large welding current and the adhesive layer is thin, the dielectric breakdown occurs, and as a result, the conductive tape can be welded. The electrode plate thus obtained was used as an electrode plate A of the present invention.

In this embodiment, the electrode plate and the current collecting tab are attached to one side surface of the electrode plate or a conductive tape by a conductive tape before the current collecting tab is directly resistance-welded to the three-dimensional porous body (electrode plate) filled with the active material. After attaching to both sides and fixing the current collecting tab, resistance welding is performed. As a result, the current collecting tab can be easily positioned, the conductive area is expanded due to the increased metal density, and the welding current is stabilized, so that welding defects are reduced.

(Comparative Example 1) On the other hand, a current collector tab was welded to the electrode plate in advance, and then a conductive tape was attached without welding, which was referred to as Comparative Example 1 and used as a comparative electrode plate B.

(Comparative Example 2) Further, a comparative electrode 2 was prepared by welding a current collecting tab and then attaching an insulating tape to it, which was referred to as a comparative electrode plate X.

Using these electrode plates A, B and X, the welding strength of the current collecting tab was compared. The comparison of the welding strength was carried out by a tensile test, and the results are shown in FIG. In Fig. 3,
The horizontal axis represents strain and the vertical axis represents welding strength.

From FIG. 3, the electrode plate A of the present invention is compared with the reference electrode plates B and X.
Indicates that the tensile strength is improved. This is because the conductive tape, the current collector tab welding part and the electrode plate are in close contact,
It is based on the fact that the welding current flows evenly during resistance welding, so the welding strength increases. As a result, welding defects on the current collecting tab were significantly reduced.

Next, the above electrode plates A, B, and X were combined with a cadmium electrode plate and wound with a separator interposed therebetween to form a spirally wound electrode body, and cylindrical nickel-cadmium batteries were produced. did. These batteries a, b,
The drop test and the vibration test were performed using x.

FIG. 4 shows the results of the vertical drop test of the batteries a, b and x from a height of 1 m. In this figure, the horizontal axis represents the number of drops and the vertical axis represents the ratio of internal resistance before and after the drop. still,
The ratio of the internal resistance before and after the drop is calculated by the following formula.

As shown in FIG. 4, as compared with the battery b having the reference electrode plate B and the battery x having the reference electrode plate X, the battery a having the electrode plate A of the present invention showed almost no increase in internal resistance even after being dropped 600 times or more. There wasn't.

After dropping the battery, the battery was disassembled and the current collecting tab welding portion was examined.
No change was observed in the reference electrode plate B. However, as is clear from FIG. 4, in the reference electrode plate B, the internal resistance increased when the number of drops exceeded 250 times.

On the other hand, in the reference electrode plate X, the welded portion is peeled off, and as a result, the internal resistance is significantly increased.

Furthermore, using the above batteries a, b, and x, high rate discharge characteristics,
The deterioration with the progress of the cycle was examined. As a result, in terms of high rate discharge characteristics and suppression of deterioration due to cycle progress, the electrode plate A of the present invention and the comparative electrode plate B are compared with each other based on the increase of the current collecting area by the conductive tape of the current collecting tab. It was found to be superior to the electrode plate X.

In addition, in the above-mentioned embodiment, as the material of the conductive tape, a 70 μm nickel foil coated with an adhesive was used, but an iron-nickel-plated nickel-resistant tape or the like may also be used. Further, since the conductive tape has flexibility, an internal short circuit does not occur when the nickel plate is used to form the spirally wound electrode body and the separator is struck.

Further, in the above-mentioned embodiment, the electrode plate 1 uses the metal fiber sintered body of nickel fiber as the active material holder, but foamed metal or the like may be used.

(G) Effect of the device According to the electrode plate of the present invention, since the welding strength of the current collecting tab can be increased and the current collecting efficiency can be improved, the vibration resistance and high rate characteristics of the alkaline storage battery using the electrode plate can be improved. Can improve. In addition, the conductive tape has flexibility,
Even if the spirally wound electrode body is configured, it does not penetrate the separator to cause an internal short circuit, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a front view of an electrode plate according to the present invention, FIG. 2 is a longitudinal sectional view of the electrode plate of FIG. 1, FIG. 3 is a view showing welding strength of a current collecting tab of the electrode plate, and FIG. FIG. 6 is a diagram showing a drop test result. 1 ... Electrode plate, 1a ... Current collecting tab welding portion, 2 ... Current collecting tab, 3a, 3b ... Conductive tape, 4 ... Spot welding point, a ... Battery of the present invention, b, x …… Comparison battery.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takei Hamamatsu 2-18, Keihan Hon-dori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (56) Bibliography Sho 61-176772

Claims (1)

[Scope of utility model registration request] 1. An electrode plate in which a three-dimensional porous body is filled with an active material, a current collecting tab welded to the electrode plate, and conductivity which covers at least one entire surface of the current collecting tab on the electrode plate. An electrode plate for an alkaline storage battery, which comprises a tape, the conductive tape being in contact with the current collecting tab and the electrode plate and being welded together with the current collecting tab on the electrode plate. The electrode plate for an alkaline storage battery according to claim 1, wherein the conductive tape is an alkali resistant metal foil.