JP2002158000A - Method of manufacturing battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a battery capable of reducing an internal short circuit when manufacturing an electrode group without impairing battery performance. SOLUTION: In this manufacturing method of the battery where among both electrodes, at least one electrode is manufacture by applying drying, cutting, rolling and punching by filling or applying paste including an active material in or to a conductive base board, or is manufactured by performing drying, rolling and cutting by filling or applying the paste including the active material in or to the conductive base board, the conductiver base board projecting to an end part of the paste-filled or applied conductive base board by the cutting or the punching is fused by irradiation of a plasma flow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a battery.

[0002]

2. Description of the Related Art A cylindrical nickel-metal hydride secondary battery, which is an example of a cylindrical alkaline secondary battery, has a positive electrode containing nickel hydroxide as an active material and a negative electrode containing a hydrogen-absorbing alloy wound spirally through a separator. It has a structure in which the turned electrode group and the alkaline electrolyte are accommodated in a container.

The positive electrode is manufactured, for example, by the method (1) or (2) described below. (1) Punching method A paste is prepared by kneading a nickel hydroxide powder, a conductive material and a binder in the presence of water. The paste is filled into a long conductive substrate having a three-dimensional structure (for example, a foamed metal) except for a lead welding portion, and dried. Subsequently, this is cut, and a positive electrode lead made of a band-shaped metal plate is welded to a portion where the paste is not filled. Next, after rolling this, a positive electrode is obtained by punching to a desired size.

(2) Cutting method A paste is prepared by kneading nickel hydroxide powder, a conductive material and a binder in the presence of water. The paste is filled into a long conductive substrate having a three-dimensional structure (for example, a foamed metal) except for a lead welding portion, and dried. Subsequently, a positive electrode lead made of a band-shaped metal plate is welded to a portion where the paste is not filled. Next, this is rolled and then cut into a desired size to obtain a positive electrode.

However, in the positive electrode manufactured by such a method, the paste at the end is peeled off at the time of cutting or punching, and the height called a burr is about several tens μm at the end.
The needle-like metal of m tends to protrude. For this reason, when the positive electrode and the negative electrode are spirally wound with a separator interposed therebetween to produce an electrode group, an internal short circuit in which burrs at the end of the positive electrode penetrate the separator and come into contact with the negative electrode is likely to occur. There is a problem. In particular, since the positive electrode manufactured by the above-described cutting method has more burrs at the ends, when an electrode group is manufactured using the positive electrode manufactured by the cutting method, the internal short circuit occurrence rate is significantly increased.

[0006] For this reason, the internal short circuit at the time of manufacturing an electrode group is reduced by subjecting the end of the positive electrode to an electric fusing process, a polishing process, or a coating process with an insulating material.

[0007]

However, when the burrs at the end of the positive electrode are to be removed by an electric fusing process, a large projecting one can be easily blown, but a very slightly projecting one is blown. And it is difficult to sufficiently suppress the internal short-circuit occurrence rate. In addition, if the edge of the positive electrode is polished, the paste is removed together with the burrs, so that the capacity of the positive electrode decreases and the discharge capacity of the battery decreases. On the other hand, when the end portion of the positive electrode is coated with an insulating material, the end portion becomes inactive, which causes a problem that the discharge capacity of the secondary battery is reduced.

An object of the present invention is to provide a method for manufacturing a battery capable of reducing internal short-circuiting during the production of an electrode group without impairing battery performance.

[0009]

According to the present invention, at least one of both electrodes is filled or coated with a paste containing an active material on a conductive substrate, dried, cut, and rolled.
In the method for producing a battery, which is produced by performing punching or filling or applying a paste containing an active material to a conductive substrate, drying, rolling, and cutting, the cutting or punching is performed. And fusing the conductive substrate protruding from the end of the conductive substrate filled or coated with the paste by irradiation of a plasma flow.

The present invention comprises a positive electrode and a negative electrode, and the positive electrode is prepared by filling or coating a conductive substrate with a paste containing nickel hydroxide and a conductive agent comprising at least one selected from metallic cobalt and a cobalt compound. Dry, cut,
In a method for producing a battery, which is produced by rolling and punching or filling or applying the paste to a conductive substrate, drying, rolling and cutting, the cutting or punching is performed. A method for manufacturing a battery, comprising: blowing a conductive substrate protruding from an end of the conductive substrate filled or coated with the paste by irradiation of a plasma flow, and forming a cobalt layer on a surface of the positive electrode. It is.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an alkaline secondary battery (square alkaline secondary battery) manufactured by the method according to the present invention will be described with reference to FIG.

As shown in FIG. 1, a metal container 1 also serving as a negative electrode terminal has a bottomed rectangular shape having an opening 2 and an inwardly projecting step 3 formed below the opening 2. Make a tube. The upper end of the opening 2 of the container 1 is bent inward. The electrode group 4 has a structure in which positive electrodes 6 and negative electrodes 7 housed in a bag-shaped separator 5 are alternately stacked, and the outermost layer is the negative electrode 7. The electrode group 4 is accommodated in the container 1 so that the negative electrode surface of the outermost layer and the inner surface along the longitudinal direction of the container 1 are in contact with each other. The alkaline electrolyte is contained in the container 1. A sealing member 8 having a positive electrode terminal and an explosion-proof function includes a rectangular sealing plate 10 having a gas vent hole 9 opened, and a cap-shaped positive terminal arranged on the sealing plate 10 so as to cover the gas vent hole 9. 1
1 and a rubber safety valve 12 disposed in a space surrounded by the sealing plate 10 and the positive electrode terminal 11 so as to close the gas vent hole 9. A plurality of gas vent holes 13 are opened in the positive electrode terminal 11. The insulating gasket 14 having a bottomed rectangular cylindrical shape having an opening at the bottom is provided in the container 1.
The sealing member 8 is arranged between the opening 2 of the container 1 and the sealing plate 10 in a compressed state, and the sealing member 8 is caulked and fixed to the opening 2 of the container 1. One end of the positive electrode lead 15 is connected to the positive electrode 5, and the other end is connected to the lower surface of the sealing plate 10.

Next, the positive electrode 6, the negative electrode 7, the separator 5
And the electrolyte will be described. 1) Positive electrode 6 This positive electrode is produced by the method (a) or (b) described below.

(A) Method for Producing First Positive Electrode (Punching Method) (First Step) A paste prepared by kneading nickel hydroxide powder, a conductive agent and a binder in the presence of water is converted into a conductive material. The substrate is filled except for the positive electrode lead welding location.

As the nickel hydroxide powder, for example, a single nickel hydroxide powder or a nickel hydroxide powder in which a metal such as zinc, cobalt, bismuth or copper is eutectic can be used. In particular, the latter positive electrode containing nickel hydroxide powder can further improve the charging efficiency in a high-temperature state.

The conductive agent comprises at least one selected from cobalt metal and a cobalt compound. As the cobalt compound, for example, a cobalt oxide (for example, Co
O, Co ₂ O ₃ ), cobalt hydroxide (for example, Co (O
H) ₂ ) and the like.

Examples of the binder include polyacrylates such as sodium polyacrylate and potassium polyacrylate, and fluorine resins such as polytetrafluoroethylene.
Alternatively, carboxymethyl cellulose and the like can be mentioned.

As the conductive substrate, for example, a conductive substrate having a two-dimensional structure (for example, a mesh-like porous metal body),
A conductive substrate having a three-dimensional structure (for example, a sponge-like (foam-like), fibrous, or felt-like porous metal body);
A conductive substrate having a two-dimensional structure with a roughened surface can be given. It is preferable that at least the surface of the conductive substrate is made of nickel.

(Second Step) The conductive substrate filled or coated with the paste is dried.

(Third step) The conductive substrate filled or coated with the paste is cut.

(Fourth Step) A positive electrode lead is welded to the unfilled portion of the conductive substrate.

The positive electrode lead can be formed from, for example, a strip-shaped nickel plate.

(Fifth Step) The conductive substrate filled or coated with the paste is rolled.

(Sixth step) The conductive substrate filled or coated with the paste is punched into a strip having a desired size.

(Seventh Step) A positive electrode is obtained by fusing the conductive substrate protruding from the end of the conductive substrate filled or coated with the paste by irradiation with a plasma flow. The fusing treatment is desirably performed at least on both ends along the longitudinal direction.

The electrode end processing apparatus used in this step will be described with reference to FIGS.

FIG. 2 is a side view showing an electrode end processing apparatus.
FIG. 3 is a sectional view showing a plasma irradiation tube of the apparatus shown in FIG.

As shown in FIG. 2, the electrode conveying means comprises an endless belt 21 and guides 22 having insulating properties disposed at both ends of the endless belt 21 along the longitudinal direction.
The plasma generating means is disposed adjacent to the guide 22 on the side of the electrode transporting means on which the paste-filled (coated) conductive substrate is supplied. The plasma generating means includes: a plasma irradiation tube 23; a high-frequency power supply 25 connected to the plasma irradiation tube 23 via a copper cord 24;
A rare gas introduction tube 26 (for example, made of vinyl chloride) for supplying a rare gas to the plasma irradiation tube 23, and a rare gas supply source (not shown) connected to the rare gas introduction tube 26. As shown in FIG.
3 is a quartz tube 27 and two brass electrode plates 28 spirally wound on the quartz tube 27 so as not to overlap each other.
A tubular insulator 29 disposed so as to surround the quartz tube 27 and the two brass electrode plates 28;
9 is composed of an aluminum mesh 30 wound around 9 for blocking electromagnetic waves.

A method for fusing a conductive substrate projecting from an end of a conductive substrate filled with paste (applied) using such an apparatus will be described.

This step is performed under atmospheric pressure.
First, the conductive substrate S that has been filled (applied) with paste is supplied to the endless belt 21 of the electrode transport means. At this time, the end of the conductive substrate S to be processed is disposed so as to be orthogonal to the traveling direction of the endless belt 21. Plasma irradiation tube 23
A rare gas such as, for example, argon gas is introduced from a rare gas introduction tube 26 into the quartz tube 27 by applying a high-frequency current from a high-frequency power supply 25 to the plasma irradiation tube 23.
A glow plasma is generated in the inside, and a plasma flow P is irradiated from the tip of the quartz tube 27 to the end of the conductive substrate S. Then, the active element in the glow plasma is attracted to the conductive substrate exposed at the end. As a result, the dense active element repeatedly emits heat due to repeated collisions, so that a pseudo arc discharge is partially generated. This pseudo arc discharge can blow the conductive substrate (needle-shaped metal) projecting from the end. In addition, the pseudo arc discharge is likely to occur at a position closest to the plasma irradiation tube 23. For this reason,
When the endless belt 21 rotates, the conductive substrate S is conveyed in a direction away from the plasma irradiation tube 23, and when the conductive substrate S moves away from the plasma irradiation tube 23, pseudo arc discharge does not occur and the fusing process ends.

(B) Second Method for Producing Positive Electrode (Cutting Method) (First Step) A paste prepared by kneading a nickel hydroxide powder, a conductive agent and a binder in the presence of water is used as a conductive substrate. Is filled except for the positive electrode lead welding part.

As the nickel hydroxide powder, the conductive agent, the binder and the conductive substrate, the same ones as described in the first method for manufacturing a positive electrode can be used.

(Second Step) The conductive substrate filled with or coated with the paste is dried.

(Fourth Step) A positive electrode lead is welded to a portion of the conductive substrate where no paste is filled.

As the positive electrode lead, the same one as described in the first positive electrode manufacturing method can be used.

(Fifth Step) The conductive substrate filled or coated with the paste is rolled.

(Sixth Step) The conductive substrate filled or coated with the paste is cut into a strip having a desired size.

(Seventh Step) A positive electrode is obtained by fusing the conductive substrate protruding from the end of the conductive substrate filled or coated with the paste by irradiation with a plasma flow.

This step can be performed by the same method as described in the first method for manufacturing a positive electrode. Irradiation with the plasma flow may be performed at least at both ends along the longitudinal direction.

It is preferable to form a cobalt layer on the surface of the positive electrode obtained by the above-mentioned first or second manufacturing method. The formation of the cobalt layer is preferably performed by plasma sputtering deposition. Plasma sputtering deposition can be performed using the above-described electrode end processing apparatus. First, a positive electrode is supplied to the endless belt 21 of the electrode transport means. The inner surface of the quartz tube 27 of the plasma irradiation tube 23 is coated with cobalt. Next, glow plasma is generated in the plasma irradiation tube 23 in the same manner as described above, so that cobalt adhering to the inner surface of the quartz tube 27 is sputter-deposited on the surface of the positive electrode.
When plasma sputtering deposition is employed, an apparatus for performing fusing by irradiation with a plasma flow can be used for forming a cobalt layer, so that fusing processing and formation of a cobalt layer can be performed continuously, and the production of a positive electrode can be performed. It can be more simplified.

In such plasma sputtering deposition, it is preferable to dispose the positive electrode at a point where the glow plasma blown out from the tip of the plasma irradiation tube disappears. By arranging the positive electrode at such a position, the generation of pseudo arc plasma can be suppressed, so that vapor deposition can be performed without causing a problem such as etching.

2) Negative electrode 4 This negative electrode is manufactured by the method (A) or (B) described below.

(A) Manufacturing Method of First Negative Electrode (Punching Method) First, a conductive substrate is filled with a paste prepared by kneading a negative electrode active material, a conductive agent and a binder together with water. Next, the conductive substrate filled or coated with the paste is dried, cut, and then rolled. Subsequently, the conductive substrate filled or coated with the paste is punched into a strip having a desired size to obtain a negative electrode.

In the first manufacturing method described above, after the punching, the end of the negative electrode may be subjected to a fusing treatment by plasma flow irradiation using the above-described electrode end processing apparatus.

(B) Second Method for Producing Negative Electrode (Cutting Method) First, a paste prepared by kneading a negative electrode active material, a conductive agent and a binder together with water is filled in a conductive substrate. Next, the conductive substrate filled or coated with the paste is dried and rolled. Subsequently, the negative electrode is obtained by cutting the conductive substrate filled or coated with the paste into a strip having a desired size.

In the above-described second manufacturing method, after cutting, the end of the negative electrode may be subjected to a fusing treatment by plasma flow irradiation using the above-described electrode end processing apparatus.

Examples of the negative electrode active material include cadmium compounds such as metal cadmium and cadmium hydroxide, and hydrogen. Examples of the host matrix of hydrogen include a hydrogen storage alloy.

In particular, the hydrogen storage alloy is the cadmium
The capacity of the secondary battery can be improved
This is preferable. The hydrogen storage alloy is specially restricted
Instead of hydrogen generated electrochemically in the electrolyte.
Can store and release the stored hydrogen easily when released
Anything can be used. For example, LaNi_Five, MmNi _Five
(Mm is misch metal), LmNi_Five(Lm is La wealth
Misched metal), and a small amount of Ni in these alloys
At least multi-elements substituted with Al and Mn
Can be The multi-element hydrogen storage alloy described above is
In addition to Al and Mn as replacement elements for Ni, Co, T
i, Cu, Zn, Zr, Cr and at least one selected from B
Both may contain one kind of element. Among them, the general formula L
nNi_wCo_xAl_yMn_z(However, Ln is a rare earth element
Element and atomic ratio w, x, y, z are 3.30 ≦ w ≦
4.50, 0.50 ≦ x ≦ 1.10, 0.20 ≦ y ≦
0.50, 0.05 ≦ z ≦ 0.20 and their total value
Represents 4.90 ≦ w + x + y + z ≦ 5.50)
This is what you want.

Examples of the conductive agent include carbon black and graphite.

Examples of the binder include polyacrylates such as sodium polyacrylate and potassium polyacrylate, and fluorine resins such as polytetrafluoroethylene;
Alternatively, carboxymethyl cellulose and the like can be mentioned.

Examples of the conductive substrate include a two-dimensional substrate such as a punched metal and an expanded metal, and a three-dimensional substrate such as a felt-like metal porous body and a sponge-like metal porous body.

3) Separator 3 Examples of the separator 3 include a nonwoven fabric made of polyamide fiber, a nonwoven fabric made of polyolefin fiber such as polyethylene and polypropylene, and a nonwoven fabric provided with a hydrophilic functional group.

4) Alkaline Electrolyte As the alkaline electrolyte, for example, a mixed solution of sodium hydroxide (NaOH) and lithium hydroxide (LiOH),
A mixture of potassium hydroxide (KOH) and LiOH, KOH
And a mixed solution of LiOH and NaOH.

According to the present invention described above, at least one of the two electrodes is formed by filling or coating a conductive substrate with a paste containing an active material, drying, cutting, rolling and punching. Or a paste containing an active material is filled or applied to a conductive substrate, dried, rolled, and cut in a manufacturing method of a battery, and the paste is filled or cut or punched. By fusing the conductive substrate protruding at the end of the applied conductive substrate by irradiation of the plasma flow, the protruding conductive substrate can be reliably blown without being influenced by the degree of protrusion, An internal short circuit when an electrode group is manufactured via a separator between the electrode and the other electrode can be suppressed, and the yield can be improved. Also, according to such a method,
Only the conductive substrate can be selectively blown, and the paste does not fall off or deteriorate during the blow, so that battery characteristics can be prevented from being impaired.

Further, according to the present invention, a positive electrode and a negative electrode are provided, and the positive electrode includes a paste containing nickel hydroxide and a conductive agent comprising at least one selected from metallic cobalt and a cobalt compound, on a conductive substrate. It is produced by filling or applying, drying, cutting, rolling, and punching, or by filling or applying the paste on a conductive substrate, drying, rolling, and cutting. In the battery manufacturing method, the conductive substrate protruding from the end of the conductive substrate filled or coated with the paste by cutting or punching is blown off by irradiation with a plasma flow, and a cobalt layer is formed on the surface of the positive electrode. As a result, not only the internal short circuit during electrode group fabrication can be avoided without impairing the positive electrode performance, but also the utilization rate of the positive electrode can be improved. That is, the conductive agent contained in the positive electrode is, for example, cobalt oxyhydroxide (Co
OOH). The conductive cobalt compound plays a role in improving conduction between nickel hydroxide and conduction between nickel hydroxide and the conductive substrate. Therefore, if the amount of the conductive agent in the positive electrode is increased, the amount of the conductive cobalt compound generated is increased, so that the utilization rate of the positive electrode is improved. Since the amount of nickel oxide needs to be reduced, the capacity of the positive electrode decreases. By forming a cobalt layer on the surface of the positive electrode as in the present invention, the amount of the conductive agent can be increased without reducing the amount of nickel hydroxide to be used. Can be improved. Therefore, it is possible to provide a battery in which an internal short-circuit during the production of the electrode group is suppressed and the discharge capacity is improved.

[0056]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

Example 1 <Preparation of Positive Electrode> A mixed powder comprising 90 parts by weight of nickel hydroxide powder and 5.5 parts by weight of cobalt monoxide powder was mixed with a binder (0.2% by weight of sodium polyacrylate powder). And 1.5 parts by weight of a dispersion of polytetrafluoroethylene in terms of solid content), and mixed with 28 parts by weight of water to prepare a paste. Then,
This paste was filled in the foamed nickel plate except for a portion where a positive electrode lead was welded, dried, and cut. Continued,
A positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate that was not filled with the paste, rolled, and then punched into a strip having a desired size.

Then, the paste-filled conductive substrate S was supplied to the endless belt 21 of the electrode transfer means of the electrode end processing apparatus having the structure shown in FIGS. 2 and 3 described above. At this time, the end of the conductive substrate S along the longitudinal direction was arranged so as to be orthogonal to the traveling direction of the endless belt 21. Glow plasma is generated in the quartz tube 27 by introducing an argon gas from the rare gas introducing tube 26 into the plasma irradiating tube 23 and applying a high-frequency current of 14.65 kHz to the plasma irradiating tube 23. A plasma flow P was applied to both ends along the longitudinal direction of the conductive substrate S from the tip to blow off the conductive substrate protruding from the both ends to obtain a positive electrode.

<Preparation of Negative Electrode> A binder composed of 1.5% by weight of polytetrafluoroethylene, 0.5% by weight of sodium polyacrylate and 0.12% by weight of carboxymethylcellulose was added to 100% by weight of a hydrogen storage alloy powder. A paste was prepared by adding and mixing 1% by weight of carbon black and 50% by weight of water as conductive agents. This paste was applied to punched metal, dried, and then pressed to form a negative electrode.

Next, such a positive electrode and a negative electrode were alternately laminated while interposing a separator made of a nonwoven fabric made of a polypropylene fiber subjected to a hydrophilic treatment to prepare an electrode group. After this electrode group was housed in a bottomed rectangular cylindrical container, an alkaline electrolyte composed of 7N potassium hydroxide and 1N lithium hydroxide was housed in the container, and the container was sealed, as shown in FIG. An F6 size nickel-metal hydride secondary battery having the structure shown in FIG.

Example 2 A prismatic nickel metal hydride secondary battery was assembled in the same manner as in Example 1 except that a cobalt layer was formed on the surface of the positive electrode by the method described below.

The positive electrode obtained by the method described in Example 1 was supplied to the endless belt 21 of the electrode transport means of the electrode end processing device. The inner surface of the quartz tube 27 of the plasma irradiation tube 23 was coated with cobalt. Next, glow plasma is generated in the plasma irradiation tube 23 in the same manner as described in the first embodiment, so that cobalt adhered to the inner surface of the quartz tube 27 is sputter-deposited on the surface of the positive electrode. A cobalt layer having a thickness of 20 μm was formed. The plasma irradiation tube 23
Was set so that the positive electrode surface was located at a point where the glow plasma irradiated from the plasma irradiation tube 23 disappeared.

Example 3 A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as that described in Example 1 was filled in the foamed nickel plate except for a portion where a positive electrode lead was welded, and dried. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where no paste was filled, rolled, and then cut into strips having desired dimensions.

Next, a fusing treatment was performed in the same manner as described in Example 1 to obtain a positive electrode.

Example 4 A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that the positive electrode described below was used.

The positive electrode obtained by the method described in Example 3 was supplied to the endless belt 21 of the electrode transfer means of the electrode end processing device. The inner surface of the quartz tube 27 of the plasma irradiation tube 23 was coated with cobalt. Next, glow plasma is generated in the plasma irradiation tube 23 in the same manner as described in the first embodiment, so that cobalt adhered to the inner surface of the quartz tube 27 is sputter-deposited on the surface of the positive electrode. A cobalt layer having a thickness of 20 μm was formed. The plasma irradiation tube 23
Was set so that the positive electrode surface was located at a point where the glow plasma irradiated from the plasma irradiation tube 23 disappeared.

Comparative Example 1 A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as that described in Example 1 was filled in the foamed nickel plate except for a portion where a positive electrode lead was welded, dried, and cut. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where no paste was filled, rolled, and then punched into a strip having a desired size to produce a positive electrode.

(Comparative Example 2) A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as that described in Example 1 was filled in the foamed nickel plate except for a portion where a positive electrode lead was welded, and dried. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where no paste was filled, rolled, and then cut into a strip having a desired size to produce a positive electrode.

Comparative Example 3 A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as that described in Example 1 was filled in the nickel foam plate except for the portion where the positive electrode lead was welded, dried and cut. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where the paste was not filled, and rolled. Next, after punching into a strip shape having the desired dimensions, both ends along the longitudinal direction were subjected to an electric fusing treatment to produce a positive electrode.

Comparative Example 4 A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as that described in Example 1 was filled in the foamed nickel plate except for a portion where a positive electrode lead was welded, and dried. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where the paste was not filled, and rolled. Next, after cutting into a strip shape having the desired dimensions, both ends along the longitudinal direction were subjected to an electric fusing treatment to produce a positive electrode.

Comparative Example 5 A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as that described in Example 1 was filled into the above-mentioned foamed nickel plate except for a portion where a positive electrode lead was welded, dried and cut. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where the paste was not filled, and rolled. Next, after punching into a strip shape having the desired dimensions, 8
A positive electrode was prepared by performing a polishing process with a file having a roughness of 00.

(Comparative Example 6) A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as that described in Example 1 was filled in the nickel foam plate except for the positive electrode lead welding portion, and dried. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where the paste was not filled, and rolled. Next, after cutting into a strip shape having the desired dimensions, both ends along the longitudinal direction were polished with a file having a roughness of 800 to produce a positive electrode.

Comparative Example 7 A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as described in Example 1 was filled in the foamed nickel plate except for a portion where the positive electrode lead was welded, dried, and cut. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where the paste was not filled, and rolled. Next, after punching into a strip shape having the desired dimensions, both ends along the longitudinal direction were covered with a polypropylene layer having a thickness of 20 μm to produce a positive electrode.

Comparative Example 8 A prismatic nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that a positive electrode was produced by the method described below.

The same paste as that described in Example 1 was filled in the foamed nickel plate except for a portion where a positive electrode lead was welded, and dried. Subsequently, a positive electrode lead made of a strip-shaped nickel plate was welded to a portion of the conductive substrate where the paste was not filled, and rolled. Next, after cutting into a strip shape having the desired dimensions, both ends along the longitudinal direction have a thickness of 20 μm.
m with a polypropylene layer to prepare a positive electrode.

With respect to the obtained secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 8, 10000 electrode groups were prepared.
A voltage of 400 V is applied to one in which each electrode group is housed in a container.
A resistance value of 0 MΩ was added for 0.1 msec, and a current passed was determined to be insulation failure, and insulation failure rate (internal short-circuit occurrence rate) was measured. The results are shown in Table 1 below.

The discharge capacity of each of the ten secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 8 was set at a rate of 0.1% at 150% and then discharged at 0.2C to 1.0V. The measurement and average discharge capacity were calculated, and the results are shown in Table 1 below. The average discharge capacity was expressed assuming that the average discharge capacity of the secondary battery of Comparative Example 1 was 100%.

[0086]

[Table 1]

As is apparent from Table 1, the secondary batteries of Examples 1 to 4 in which positive electrodes are produced by a method in which a conductive substrate protruding from an end of a paste-filled substrate is blown by irradiation with a plasma flow are punched out. It can be seen that in both the method and the cutting method, the internal short-circuit occurrence rate at the time of preparing the electrode group can be reduced as compared with Comparative Examples 1 to 8, and a decrease in discharge capacity can be avoided. Further, the secondary batteries of Examples 2 and 4 in which a cobalt layer is formed on the surface of the positive electrode can improve the discharge capacity as compared with the secondary batteries of Examples 1 and 3 in which no cobalt layer is formed on the surface of the positive electrode. I understand.

In the above-described embodiment, an example in which the present invention is applied to a prismatic nickel-metal hydride secondary battery has been described. However, a spirally wound electrode group having a separator between a positive electrode and a negative electrode has a bottomed cylindrical shape. The same can be applied to a cylindrical nickel-metal hydride secondary battery having a structure housed in a container.

[0089]

As described above, according to the present invention, it is possible to provide a method of manufacturing a battery in which the rate of occurrence of internal short-circuits during the production of the electrode group is reduced without impairing the battery performance.

[Brief description of the drawings]

FIG. 1 is a partially cutaway sectional view showing an alkaline secondary battery manufactured by a method according to the present invention.

FIG. 2 is a side view showing an electrode end processing apparatus used in the method according to the present invention.

FIG. 3 is a sectional view showing a plasma irradiation tube of the electrode end processing apparatus of FIG. 2;

[Explanation of symbols]

 21 ... Endless belt,  22 ... Guide,  23: Plasma irradiation tube,  25 ... High frequency power supply 26 ... Rare gas introduction pipe.

Claims (2)

[Claims] 1. At least one electrode of both electrodes is:
Filled or coated with a paste containing an active material on a conductive substrate, dried, cut, rolled, produced by punching, or filled or coated with a paste containing an active material on a conductive substrate, A method for producing a battery, which is manufactured by drying, rolling, and cutting, wherein the plasma substrate is irradiated with a conductive substrate protruding from an end of the conductive substrate filled or coated with the paste by the cutting or the punching. A method for producing a battery, comprising: 2. A positive electrode and a negative electrode, wherein the positive electrode is filled or coated with a paste containing nickel hydroxide and a conductive agent comprising at least one selected from metallic cobalt and a cobalt compound on a conductive substrate, and dried. Cut, rolled,
In a method for producing a battery, which is produced by punching or filled or coated with the paste on a conductive substrate, dried, rolled, and cut, the paste is formed by cutting or punching. A method for producing a battery, comprising: blowing a conductive substrate protruding from an end of a conductive substrate filled or coated with, by irradiation with a plasma flow, and forming a cobalt layer on a surface of the positive electrode.