JPH10223216A - Manufacture of electrode for cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good electrode in which the biting quantity in the metal lic porous body of a resistance welded part is increased, the welding tensile strength is improved, and no inconvenience such as detachment of a metallic collector plate present by applying the fixed pressure in a direction perpendicu lar to the surface of the resistance welded metallic collector plate. SOLUTION: An ultrasonic oscillator is placed on a part of a center part of an upper edge of a nickel electrode 1, and the ultrasonic oscillation is generated to make the active material of the part fall out. A nickel collector plate 2 is welded to a sponge-like nickel porous body, which is a metallic porous body left in the active material fallen out part 3 at a resistance welded part 4. The nickel porous body, which contains the resistance welded part 4 and which the active material is made to fall out is pressed with pressure in a direction perpendicular relative to the surface of the nickel electrode as a pressure pressed part 5. The contact area of the three-dimensional metallic porous body with the metallic collector plate is increased, the biting quantity of the resistance welded part 4 into the metallic porous body is increased, and the welding tensile strength can be improved.

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 method of manufacturing a battery electrode, particularly an electrode in which a metal current collector is partially welded.

[0002]

2. Description of the Related Art Battery electrodes are roughly classified into paste electrodes, sintered electrodes, pocket electrodes, and the like. In recent years, in the case of electrodes for alkaline storage batteries, in particular, nickel electrodes, paste-type electrodes in which a paste-like kneaded material is filled in a metal support made of a strip-shaped porous metal having a three-dimensionally connected space or a nonwoven fabric of nickel fibers have been adopted. ing. These metal supports have a porosity of about 95%, and the pore diameter of the space is a few hundred μm at the maximum, so that the paste-like active material or the active material powder can be filled at a high density.

In order to extract the amount of electricity from the active material filled in the above configuration, it is necessary to resistance weld a metal current collector to the electrode. In order to provide the welded portion, as shown in FIG. 3, it was necessary to press a part of the metal support 6 in advance and then fill the active material. However, in the subsequent pressing process for adjusting the electrode thickness, the boundary between the welded portion of the current collector 2 and the electrode 1 and the active material-filled portion is distorted,
The electrode cracked. The cracks caused a decrease in the discharge capacity of the battery. FIG. 4 shows a sectional view thereof.

[0004] In order to solve this problem, there is a method in which a press portion for welding before filling the active material is not provided, and after filling, the active material is dropped from a part of the electrode by ultrasonic vibration to provide a welded portion.

[0005]

However, even if the metal current collector plate is resistance-welded to the portion where the active material has fallen, the welding tensile strength is low, and the internal resistance of a battery manufactured using this electrode also increases. When the welding tensile strength was low, the metal current collector plate was likely to come off, the amount of electricity could not be sufficiently collected, and the discharge capacity remained low. Further, when the internal resistance of the battery is increased, there is a problem that the discharge efficiency is reduced and the discharge capacity is reduced.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an electrode comprising a plate-shaped porous metal body having a three-dimensionally continuous space, and an active material filled in the space. A metal current collector is resistance-welded to the part where only the active material was dropped by applying ultrasonic vibration to a part of the metal current collector, and the surface of the welded metal current collector was pressed at a constant pressure from the vertical direction. This is a method for producing a battery electrode.

[0007]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, only an active material is dropped by applying ultrasonic vibration to a part of an electrode.
A method for manufacturing an electrode for a battery, characterized in that a metal current collector plate is resistance-welded to the portion, and pressure is applied to the surface of the welded metal current collector plate at a constant pressure from a vertical direction.

In this case, the electrode has a pressure-pressed portion on a part of the resistance-welded metal current collector plate, and a contact area between the metal porous plate exposed by the ultrasonic vibration and the metal current collector plate. And the amount of penetration of the resistance collector by the current collector plate into the porous metal body increases, so that the welding tensile strength is improved and problems such as the metal collector plate coming off can be prevented. Also, since the internal resistance of the battery manufactured using this electrode is reduced,
Discharge efficiency can be improved.

According to a second aspect of the present invention, an oscillation frequency and an amplitude of the ultrasonic vibrator are defined.

In this case, the frequency of the oscillating ultrasonic wave is 15
kHz to 40 kHz, amplitude 50 to 150 μm
Therefore, only the active material filled in the metal support can be dropped. If the frequency of the ultrasonic wave is less than 15 kHz or the amplitude is less than 50 μm, the active material cannot be sufficiently dropped, a large amount of the active material remains, and poor welding occurs during resistance welding. In addition, the frequency is 41 kHz
If z or more, or if the amplitude is more than 151 μm, the ultrasonic vibration is too strong and breaks the porous metal body, so that a resistance welded portion cannot be secured.

According to the present invention, the weight ratio of the active material remaining in the portion dropped off by the ultrasonic vibration is defined.

[0012] In this case, the active material has a resistance welding portion in which the weight ratio of the active material remaining at the portion where the active material is dropped off by the ultrasonic vibration is 20% by weight or less. Since the tensile strength can be improved, problems such as detachment of the metal current collector can be prevented.

According to a fourth aspect of the present invention, a range A in which pressing is performed in the vertical direction is defined. That is, A is equal to or greater than the range B of the metal current collector disposed on the electrode, and equal to or less than the range C (B ≦ A ≦ C) where the active material in the electrode is dropped.

[0014] In this case, the contact area between the metal current collector plate and the electrode increases, the amount of bite of the resistance welding portion into the porous metal increases, and the tensile strength of welding improves, so that the metal current collector plate comes off. And the like can be prevented. In addition, since the internal resistance of a battery manufactured using this electrode is also reduced, discharge efficiency can be improved.

According to a fifth aspect of the present invention, the thickness of the electrode after pressing the portion where the active material has fallen is 10% to 10% of the thickness of the electrode portion where the active material has not fallen. 5
0%.

In this case as well, the contact area between the metal current collector plate and the electrode increases, the amount of bite into the porous metal body of the resistance welding portion increases, and the welding tensile strength improves.

[0017]

Next, specific examples of the present invention will be described.

FIG. 1 shows the surface shape of an electrode A in an embodiment of the present invention, and this structure will be described below.

With respect to 85% by weight of nickel hydroxide powder,
10% by weight of a cobalt oxide powder and 5% by weight of a nickel metal powder were added, and the powders were mixed. Water was added to the mixture so that the ratio in the total paste was 25% by weight. . This active material was extrusion-filled in a fixed amount of 40 to 50 g into a sponge-like nickel porous body having a porosity of 95%, an average pore diameter of 200 µm, a width of 250 mm, a length of 155 mm, and a thickness of 2 mm. After that, the porous metal body filled with the paste was dried at 90 ° C. for 1 hour, pressurized by a roll press, adjusted to a thickness of 0.8 mm, and then 41 m in length.
m, 38 mm wide.

As shown in FIG. 1, a part of the central part of the upper edge of the nickel electrode 1 thus obtained is 8 mm wide and 4 m long.
The ultrasonic transducer is applied in the range of m and the frequency is 28 kHz.
Ultrasonic vibration of z and amplitude of 100 μm was oscillated to remove 0.04 g of the active material in that portion. Therefore, as for the active material residual ratio, 0.01 g is 20 wt% because 100 wt% of the active material in that portion is 0.05 g. A nickel current collector plate 2 having a length of 10 mm, a width of 2 mm, and a thickness of 0.15 mm is welded to the sponge-like nickel porous body, which is a porous metal body remaining in the active material falling-off portion 3, at the resistance welding portion 4,
A range of 7 mm in width and 3 mm in length on the nickel porous body from which the active material has been removed, including the welded portion 4, is pressed as a pressing portion 5 from a direction perpendicular to the nickel electrode surface at a constant pressure. The thickness was adjusted to 0.16 mm, which is 20% for most electrode thicknesses of 100%.

For the electrode A of the present invention, the tensile strength was measured with a push-pull gauge in order to measure the welding strength. The nickel electrode was used as a positive electrode, the hydrogen storage alloy electrode was used as a negative electrode, spirally wound through a polypropylene separator, inserted into the battery case, injected with an alkaline electrolyte, and the sealing plate was used as a positive nickel current collector plate. The internal resistance of the battery produced by resistance welding and sealing was measured. The results are shown in (Table 1). Table 1 also shows the results of evaluation of a conventional electrode and an electrode manufactured by changing the pressing conditions and ultrasonic vibration conditions for the electrode A.

[0022]

[Table 1]

The electrode of the present invention shown in Table 1 has a higher welding tensile strength than the conventional electrode, and can also lower the internal resistance of the battery. Could be improved.

[0024]

As described above, according to the present invention, since the pressurized portion is provided on the resistance-welded metal current collector plate, the contact between the three-dimensional porous metal body exposed by the ultrasonic vibration and the metal current collector plate is achieved. Since the area is increased and the amount of bite of the resistance welded portion into the porous metal body is increased, the welding tensile strength can be improved, and a good electrode free from defects such as the detachment of the metal current collector plate can be obtained.

Further, since the internal resistance of a battery manufactured using this electrode is also reduced, a battery having good discharge efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a surface view of a nickel electrode according to an embodiment of the present invention.

FIG. 2 is a sectional view of a nickel electrode according to an embodiment of the present invention.

FIG. 3 is a surface view of a conventional nickel electrode.

FIG. 4 is a sectional view of a conventional nickel electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nickel electrode 2 Nickel current collecting plate 3 Active material falling-off part 4 Resistance welding part 5 Pressing part 6 Nickel porous body

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsuya Okamoto, Inventor 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A metal plate comprising a plate-shaped porous metal body having a three-dimensionally continuous space and an active material filled in the space, and a portion of the metal material collected only in the active material dropped by ultrasonic vibration. A method for producing an electrode for a battery, comprising: performing resistance welding on an electric plate; and then pressing the surface of the welded metal current collector plate at a constant pressure in a vertical direction. 2. The oscillation frequency of the ultrasonic vibrator is 15k.
Hz to 40 kHz, and the amplitude is 50 to 150 μ
The method for producing an electrode for a battery according to claim 1, wherein only the active material is dropped from the space of the porous metal body by the ultrasonic vibration of m. 3. The battery according to claim 1, wherein the weight ratio of the active material remaining in the portion to be dropped by the ultrasonic vibration is 20% by weight or less with respect to 100% by weight of the active material filled in the entire portion to be dropped. Method of manufacturing electrodes. 4. A range A in which the current collector plate is pressed from its vertical direction.
2. The method for producing a battery electrode according to claim 1, wherein the length of the electrode is not less than the range B of the entire portion of the metal current collector plate disposed on the electrode and not more than the range C of the electrode from which the active material has been dropped. 5. The thickness of the electrode after pressing the portion of the active material from which the active material has fallen is equal to the thickness of the electrode portion from which the active material has not fallen.
The method for producing an electrode for a battery according to claim 1, wherein the content is 10% to 50% with respect to%.