JP2002260628A - Positive electrode for alkaline secondary battery, manufacturing method of positive electrode for the alkaline secondary battery, and the alkaline secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive electrode for an alkaline secondary battery, capable of enhancing the welding strength of the conducive substrate and the collector. SOLUTION: The positive electrode for an alkaline secondary battery is provided with a conductive substrate having a three-dimensional structure; the collector 3 resistance-welded to the conductive substrate; and a positive electrode black mix for cell 2 retained by the conductive substrate and including an active substance, and in which is characterized that the collector 3 has a plurality of projections 4 and the sum of occupancy areas of the respective projection is within 10 to 60% of a facing area of the collector 3 and the conductive substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positive electrode for an alkaline secondary battery, a method for producing a positive electrode for an alkaline secondary battery, and an alkaline secondary battery.

[0002]

2. Description of the Related Art As alkaline secondary batteries, nickel cadmium secondary batteries and nickel hydrogen secondary batteries are known. Due to the increasing demand for high-capacity batteries due to the recent spread of PCs (personal computers) and mobile phones, and environmental issues, nickel-metal hydride secondary batteries have become mainstream as alkaline secondary batteries.

[0003] In the automobile industry, electric vehicles (EVs) which replace gasoline engine vehicles due to environmental problems,
The development of assist type electric vehicles (HEVs) is active and some of them have been commercialized.

[0004] By the way, current collection of a positive electrode of an alkaline secondary battery such as a nickel hydride secondary battery is performed by welding a strip-shaped metal plate as a current collector to a conductive substrate of the positive electrode by resistance welding, ultrasonic welding, or the like. This is achieved by electrically connecting the band-shaped metal plate to a sealing member also serving as a positive electrode terminal. When the conductive substrate and the current collector are welded, if an active material is present at the welding location, welding failure such as splash is likely to occur. Therefore, it is desired that the welding location be free of the active material. Various proposals have been made as a method for preventing the active material from being held at the portion of the conductive substrate where the current collector is welded.

[0005] First, a conductive substrate is partially pressed to form a low porosity region, and then the conductive substrate is filled with an active material-containing paste (hereinafter referred to as a paste), dried, and rolled. Thereafter, it has been proposed to remove the paste retained in the low porosity region to form a current collector welding region (for example, Japanese Patent Application Laid-Open No. 9-22704).
There is also known a method of masking a desired portion of a conductive substrate with a tape or the like and then filling the paste with a paste. Furthermore, there has been proposed a method of removing the paste at the welding location by ultrasonic removal or piercing after filling the conductive substrate with the paste (for example, Japanese Patent Application Laid-Open No. 9-204911). In particular, in terms of productivity, once the conductive substrate is filled with paste, dried, rolled,
It is effective to remove the paste from the current collector welding point.

However, in the method in which the paste once filled is removed after rolling, if the amount of the active material filled in the positive electrode is increased to increase the capacity, the active material is difficult to be removed. Therefore, there is a problem that welding failure occurs frequently. In addition, excessive ultrasonic vibration and piercing may cause excessive damage to the conductive substrate and reduce the welding strength between the current collector and the conductive substrate, since the active material is not sufficiently removed. Occurs.

As described above, as the active material filling amount of the positive electrode increases, the damage to the substrate during the removal of the active material is unavoidably increased. As a method for welding the current collector, resistance welding is more preferable than ultrasonic welding from the viewpoint of minimizing damage to the substrate.

[0008] As resistance welding, multipoint spot welding and seam welding are generally used.

[0009]

However, since the conductive substrate of the positive electrode has a three-dimensional porous structure such as a felt-like porous metal body, it has many fine irregularities on its surface, so that multipoint spot welding or seam welding is performed. However, there is a problem that sufficient welding strength cannot be ensured. If the welding pressure or welding current is increased to secure the welding strength, there is a possibility that the same problem as in the case of ultrasonic welding, that is, the conductive substrate may be damaged.

An object of the present invention is to provide a positive electrode for an alkaline secondary battery and an alkaline secondary battery capable of improving the welding strength between a conductive substrate and a current collector.

An object of the present invention is to provide a method for producing a positive electrode for an alkaline secondary battery, which can improve the welding strength between a conductive substrate and a current collector and is excellent in productivity.

[0012]

The positive electrode for an alkaline secondary battery according to the present invention comprises: a conductive substrate having a three-dimensional structure;
In a positive electrode for an alkaline secondary battery including a current collector that is resistance-welded to the conductive substrate and a positive electrode mixture held on the conductive substrate and containing an active material, the current collector has a plurality of protrusions. Wherein the total occupied area of each of the protrusions is within a range of 10 to 60% of the area of the opposing surface between the current collector and the conductive substrate.

[0013] An alkaline secondary battery according to the present invention includes a conductive substrate having a three-dimensional structure, a current collector to be resistance-welded to the conductive substrate, and an active material held by the conductive substrate. In the alkaline secondary battery including the positive electrode including the positive electrode mixture and the negative electrode, the current collector has a plurality of protrusions, and the total area occupied by each of the protrusions is equal to the current collector and the conductive property. It is characterized in that it is within the range of 10 to 60% of the area facing the substrate.

The method for producing a positive electrode for an alkaline secondary battery according to the present invention comprises the steps of: holding a positive electrode mixture containing an active material on a conductive substrate having a three-dimensional structure; Forming a positive electrode mixture non-holding region on the conductive substrate by removing by ultrasonic vibration, and a step of resistance welding a current collector to the positive electrode mixture non-holding region of the conductive substrate, The current collector has a plurality of protrusions, and the total area occupied by each of the protrusions is within a range of 10 to 60% of the facing area between the current collector and the positive electrode mixture non-holding region. It is a feature.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A positive electrode for an alkaline secondary battery according to the present invention will be described below with reference to FIGS.

FIG. 1 is a front view showing an example of the positive electrode for an alkaline secondary battery according to the present invention. FIG. 2 is a cross-sectional view obtained when the current collector of the positive electrode in FIG. 1 is cut along the short side direction. FIG. 3 is a cross-sectional view for explaining a step of resistance-welding the current collector to the conductive substrate.

The positive electrode for an alkaline secondary battery includes a conductive substrate having a three-dimensional structure, a current collector welding region 1 without a positive electrode mixture formed at an end of the conductive substrate, and a conductive substrate. A positive electrode mixture 2 containing an active material, which is held except for the current collector welding region 1, and a current collector 3 that is resistance-welded to the current collector welding region 1. The current collector 3 is formed of a band-shaped metal plate having a plurality of (six in the case of FIGS. 1 and 2) circular projections 4. The total area occupied by the projections 4 is the sum of the area occupied by each of the projections 4 (in FIGS. 1 and 2, the area defined by the outer diameter), and the current collector 3 and the conductive substrate (current collector welding). It is preferable to set it within the range of 10 to 60% of the area facing region 1). The facing area between the current collector 3 and the conductive substrate (current collector welding region 1) is a region indicated by oblique lines in FIG.
Is calculated by the product of the length L ₂ of the current collector welded region 1 which is perpendicular to the width L ₁ of the current collector and the L _1.

The reason why the total value of the occupied areas S of the projections 4 is used will be described. The conductive substrate having a three-dimensional structure has fine irregularities on the surface due to the structure and the removal of the positive electrode mixture (for example, by ultrasonic vibration) for forming the current collector welding region. For this reason, the portion of the projection of the current collector that is actually welded to the conductive substrate fluctuates depending on the surface state of the conductive substrate and is uncertain. Therefore, if the area of the specific portion (for example, the top) of the projection is regulated, it becomes difficult to secure a sufficient welding area. By restricting the total area of the occupied areas S of the projections 4 to a specific range as in the present invention, it is possible to secure sufficient welding strength regardless of the surface shape of the conductive substrate.

The total area occupied by the projections 4 is defined in the above range for the following reason. The total occupied area of the projections 4 is 10% of the area of the facing between the current collector 3 and the conductive substrate
If the value is less than the above, the welding area between the current collector 3 and the conductive substrate is insufficient, and it becomes difficult to improve the welding strength between the current collector 3 and the conductive substrate. In addition, the resistance between the current collector and the conductive substrate increases due to the shortage of the welding area, so that the active material utilization rate of the positive electrode decreases. On the other hand, if the total occupied area of the projections 4 exceeds 60% of the facing area, it is difficult to distribute the current evenly, so that the possibility of the occurrence of projections that are not welded increases. A more preferable range of the total occupied area of the projections 4 is 20 to 50% of the area of the current collector 3 and the conductive substrate facing each other.

It is preferable that the number of projections is in the range of 1 to 10. When the number of projections is small, it is necessary to increase the size of each projection in order to set the total occupied area of the projections to the target value, and the density of the welding current concentrated on the projections is reduced, so that high welding strength can be obtained. May be gone. On the other hand, if the number of protrusions is too large, it becomes difficult for the current to be evenly dispersed, and therefore, the possibility of occurrence of protrusions that are not welded increases.

The depth D of each projection 4 (the distance between the welding surface of the current collector and the top of the projection) is preferably in the range of 0.2 to 0.5 mm. If the depth D of the projections 4 is less than 0.2 mm, the flatness of the welding surface of the current collector becomes high, current cannot be sufficiently concentrated on the projections, and high welding strength may not be obtained. There is. On the other hand, the depth D of the projection 4
Exceeds 0.5 mm, there is a high possibility that the metal plate will be torn when forming projections on the metal plate.

In FIGS. 1 and 2 described above, the shape of the projection is circular. However, the shape of the projection is not particularly limited, and may be, for example, an ellipse, a triangle, a rectangle, a polygon, or the like.

Examples of the metal material forming the current collector include nickel and a nickel-plated iron steel plate (NPS).

As a method of processing the projections on the strip-shaped metal plate, for example, press working and knurling can be adopted. Pressing is suitable for a metal plate made of nickel, while projections can be formed on a metal plate made of NPS by knurling.

When the shape of the electrode group is of a spiral type, it is desirable that the current collector is made of nickel. The thickness of the nickel metal plate is preferably in the range of 0.06 to 1.5 mm.

Examples of the conductive substrate having the three-dimensional structure include two-dimensional substrates such as foamed metal (porous sponge-like metal), nickel fibrous metal porous body (felt-like metal porous body), and punched metal. A material having irregularities on the periphery of the hole can be used. The conductive substrate can be formed of, for example, nickel, nickel-plated metal, or the like.

The active material contained in the positive electrode mixture includes, for example, nickel hydroxide.

As the nickel hydroxide, nickel hydroxide in which at least one metal selected from zinc and cobalt is eutectic, or non-eutectic nickel hydroxide can be used.

A conductive layer containing cobalt oxyhydroxide (CoOOH) can be formed on the surface of the nickel hydroxide. When the conductive layer is formed, the positive electrode mixture does not need to contain a conductive material described later.

The positive electrode mixture can contain a conductive material. As the conductive material, for example metallic cobalt, cobalt compounds (e.g., cobalt oxide such as CoO, cobalt hydroxide such as Co (OH) _2), and the like. As the conductive material, one or more selected from the above-described types can be used. The conductive material can be contained in the positive electrode mixture in the form of powder or a layered material covering the surface of the nickel hydroxide powder. The positive electrode mixture may contain both a nickel hydroxide powder whose surface is coated with a conductive material and a powder of a conductive material.

The positive electrode mixture may contain a binder. Examples of the binder include carboxymethyl cellulose, methyl cellulose, sodium polyacrylate, polytetrafluoroethylene, and the like.

The positive electrode for an alkaline secondary battery according to the present invention comprises:
For example, it is manufactured by the method described below.

First, a paste containing an active material, a binder and water is prepared. By filling the paste into a conductive substrate having a three-dimensional structure, drying and pressing,
The positive electrode mixture is held on the conductive substrate. The obtained positive electrode mixture holding substrate is cut into a desired size. Next, the positive electrode mixture at a desired position at the end of the positive electrode mixture holding substrate is removed by, for example, ultrasonic vibration to form a region where the positive electrode mixture is not held.

Subsequently, as shown in FIG. 3, the current collector 3 is arranged on one surface (current collector welding region 1) of the positive electrode mixture non-holding region (conductive substrate) 5 so that the projection 4 comes into contact with the current collector. After that, the welding electrode 6 (for example, the positive electrode side) is arranged above the current collector 3. Further, a welding electrode 7 having an opposite pole is arranged on the other surface of the positive electrode mixture non-holding region 5. By applying pressure to the conductive substrate and the current collector 3 with the welding electrodes 6 and 7 and applying a welding current, the current collector 3 is resistance-welded (projection-welded) to the conductive substrate to obtain a positive electrode. Reference numeral 8 in FIG. 3 indicates a positive electrode mixture holding region. In resistance welding, it is desirable to weld all projections at once. If the welding is performed several times, a current flows to the already welded portion, that is, a reactive current is generated at the time of the second and subsequent weldings, and the possibility of poor welding increases.

In such a manufacturing method, preliminary cutting may be performed between the paste drying step and the pressing step.

In a case where a spiral electrode group including a positive electrode and a negative electrode and a separator disposed between the positive electrode and the negative electrode is used in the alkaline secondary battery, the current collector 3 is used for forming the electrode group. Preferably, it is welded to the positive electrode surface located inside during winding. When the current collector is welded to the positive electrode surface located outside at the time of winding for electrode group production,
This is because, at the time of winding, the edge of the current collector may rebound, break through the separator, and come into contact with the negative electrode.

Next, an alkaline secondary battery provided with the positive electrode according to the present invention will be described.

This alkaline secondary battery comprises the positive electrode according to the present invention, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an alkaline electrolyte.

Hereinafter, the negative electrode, the separator, and the alkaline electrolyte will be described.

1) Negative electrode The negative electrode contains a hydrogen storage alloy.

This negative electrode is made of, for example, hydrogen storage alloy powder,
The paste is prepared by kneading a conductive material and a binder in the presence of water to prepare a paste, filling the paste into a conductive substrate, drying, and then pressing.

As the hydrogen storage alloy, for example, La
Ni _5, MmNi ₅ (Mm is misch metal), LmN
i ₅ (Lm is La-enriched misch metal), and part of Ni of these alloys is Al, Mn, Co, Ti, Cu, M
at least one selected from g, Ca, Zr, Cr and B
Rare earth-based hydrogen storage alloys represented by multi-element-based alloys substituted with various elements can be given. Above all, the general formula _{LnNi v Co w Mn x Al y} Zr z ( However, Ln is one or more kinds of rare earth elements, preferably those containing La, total atomic ratio v, w, x, y and z Value is 5.
1 ≦ v + w + x + y + z ≦ 5.4) is preferably used.

Examples of the conductive material include graphite,
Carbon black or the like can be used.

Examples of the binder include carboxymethyl cellulose, methyl cellulose, sodium polyacrylate, polytetrafluoroethylene, polyvinyl alcohol (PVA), and styrene butadiene rubber (SB).
R) and the like.

Examples of the conductive substrate include a two-dimensional substrate such as a punched metal, an expanded metal, and a nickel net, and a three-dimensional substrate such as a nickel fibrous metal porous material and a sponge-like metal substrate. .

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

3) 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.

A cylindrical alkaline secondary battery which is an example of the alkaline secondary battery according to the present invention will be described with reference to FIG.

That is, in the bottomed cylindrical container 11,
An electrode group 15 produced by laminating the positive electrode 12, the separator 13, and the negative electrode 14 and winding the same spirally is accommodated. The negative electrode 14 is arranged at the outermost periphery of the electrode group 15 and is in electrical contact with the container 11. The alkaline electrolyte is contained in the container 11. A circular sealing plate 17 having a hole 16 in the center is arranged at the upper opening of the container 11. The ring-shaped insulating gasket 18 is disposed between the peripheral edge of the sealing plate 17 and the inner surface of the upper opening of the container 11, and the sealing plate is formed on the container 11 by caulking to reduce the diameter of the upper opening inward. 17 is hermetically fixed via the gasket 18. One end of the positive electrode current collector 3 is connected to the positive electrode 12,
The other end is connected to the lower surface of the sealing plate 17. The hat-shaped positive electrode terminal 19 is provided on the sealing plate 17 with the hole 1.
6 so as to cover it. Rubber safety valve 2
Numeral 0 is disposed so as to close the hole 16 in a space surrounded by the sealing plate 17 and the positive electrode terminal 19. A circular holding plate 21 made of an insulating material having a hole in the center is arranged on the positive electrode terminal 19 such that a projection of the positive terminal 19 projects from the hole of the holding plate 21.
The outer tube 22 covers the periphery of the holding plate 21, the side surface of the container 11, and the bottom periphery of the container 11.

The above-described positive electrode for an alkaline secondary battery according to the present invention comprises a conductive substrate having a three-dimensional structure, a current collector which is resistance-welded to the conductive substrate, and a collector held by the conductive substrate. In the positive electrode for an alkaline secondary battery including a positive electrode mixture containing an active material, the current collector has a plurality of protrusions, and the total area occupied by each of the protrusions is equal to the current collector and the conductive substrate. Is within a range of 10% to 60% of the area of the surface facing.

According to such a positive electrode, when the current collector is resistance-welded to the conductive substrate, regardless of the surface shape of the conductive substrate, the welding current is surely and sufficiently concentrated on all protrusions. Therefore, high welding strength can be ensured without applying an excessive welding current or welding pressure. As a result, the electron conductivity of the substrate can be maintained by minimizing the damage to the conductive substrate, and the resistance between the current collector and the conductive substrate can be reduced. Usage rate can be improved,
Particularly, it is possible to realize an alkaline secondary battery having excellent large current discharge characteristics.

The positive electrode for an alkaline secondary battery according to the present invention comprises:
A step of holding a positive electrode mixture containing an active material on a conductive substrate having a three-dimensional structure; and a step of removing a part of the positive electrode mixture by ultrasonic vibration to form a positive electrode mixture non-holding region on the conductive substrate. Forming a current collector, and resistance welding a current collector to the positive electrode mixture non-holding region of the conductive substrate, wherein the current collector has a plurality of protrusions, and each of the protrusions occupies an area. Is within the range of 10 to 60% of the facing area between the current collector and the positive electrode mixture non-holding region.

When the positive electrode mixture is removed by ultrasonic vibration, the positive electrode mixture can be reliably removed within a short time even if the amount of the positive electrode mixture is large due to high capacity. Become. However, damage to the conductive substrate is slightly increased. According to the present invention, the current collector can be resistance-welded with high welding strength to the conductive substrate having such a rough surface while minimizing damage to the substrate. A positive electrode with improved material utilization can be manufactured with high productivity.

[0054]

DETAILED 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 Paste-Type Positive Electrode> A mixed powder composed of 90% by mass of nickel hydroxide powder and 10% by mass of cobalt monoxide powder was mixed with 3% by mass of carboxymethyl cellulose (CMC) and polytetrafluoroethylene. A paste was prepared by adding 5% by mass, adding 45% by mass of water to these, and kneading. Next, the paste is filled into a sponge-like nickel porous body which is a conductive substrate having a three-dimensional porous structure, dried, and then roll-pressed and roll-formed to form a conductive substrate filled with the positive electrode mixture. I got The mixture-filled substrate was cut into a predetermined size.

Next, the mixture in the area of 5 mm × 5 mm at the longitudinal end of the mixture-filled substrate was removed by ultrasonic vibration to provide a positive electrode mixture non-holding area.

On the other hand, a strip-shaped (strip-shaped) nickel plate having a width of 3 mm and a thickness of 0.1 mm has an outer diameter of 1 mm by pressing.
mm, and six circular projections having a depth D of 0.4 mm are formed,
A current collector was obtained. The total area occupied by the protrusions (the area defined by the outer diameter of the protrusions) was equivalent to 30% of the facing area between the current collector and the conductive substrate. After arranging the current collector on one surface of the positive electrode mixture non-holding region so that the projections were in contact with the current collector, the welding electrode was arranged above the current collector. Further, a welding electrode having an opposite electrode was arranged on the other surface of the positive electrode mixture non-holding region. The current collector is resistance-welded (projection welded) to the conductive substrate by pressing the conductive substrate and the current collector at 5 kgf with a pair of welding electrodes and applying a welding current of 2 KA, as shown in FIG. 1 described above. A paste-type nickel electrode having a structure was obtained.

<Preparation of Paste Type Hydrogen Storage Alloy Negative Electrode> 100% by mass of hydrogen storage alloy powder, 0.5% by mass of sodium polyacrylate and carboxymethyl cellulose (CM
C) 0.12% by mass, polytetrafluoroethylene
5% by mass and 1% by mass of carbon black,
A paste was prepared by kneading with 0% by mass. This paste was applied on both sides of a punched metal as a conductive substrate, dried, and then roll-formed by a roller press to produce a negative electrode.

Next, an electrode group was prepared by spirally winding the sheet while interposing a polyolefin nonwoven fabric subjected to hydrophilic treatment as a separator between the positive electrode and the negative electrode as a separator. The production of the electrode group was performed while arranging the positive electrode such that the current collector was located on the positive electrode surface which was inside during winding. Such an electrode group was housed in a bottomed cylindrical metal container also serving as a negative electrode terminal. Next, KOH is placed in the container.
By injecting an alkaline electrolyte mainly composed of, for example, and subjecting it to sealing treatment, an AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 4 having a theoretical capacity of 1200 mAh was manufactured.

(Examples 2 to 4 and Comparative Examples 1 and 2) The outer diameters of circular projections, the number of projections, and the total area occupied by the projections are shown in Table 1 below.
A cylindrical nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except for the change as shown in FIG.

Comparative Example 3 A cylindrical nickel-metal hydride secondary battery was assembled in the same manner as in Example 1 except that no protrusion was formed on the current collector.

The obtained secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 3 were prepared by 500 pieces, and welding defects were evaluated by the method described below. The welding defect rate is shown in Table 1 below.

With respect to the positive electrode of each secondary battery, the lower side was fixed, the tip of the current collector was pulled upward at a speed of 20 mm / min, and the tension when the current collector was broken was measured.
Those having gf or less were evaluated as poor welding.

[0064]

[Table 1]

As is apparent from Table 1, the secondary batteries of Examples 1 to 4 in which the total area occupied by the projections is in the range of 10 to 60% of the area of the opposing surface between the current collector and the conductive substrate have a high welding strength. It can be seen that the rate of occurrence of defective products with a shortage was lower than Comparative Examples 1 to 3. In particular, according to Comparative Example 3 in which no protrusion is provided on the current collector, it is understood that the current collector can hardly be welded to the conductive substrate under the above-described conditions of the welding current and the welding pressure.

In the above-described embodiment, an example in which the present invention is applied to a cylindrical alkaline secondary battery has been described. However, a laminate including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode is used as an electrode. The same can be applied to the prismatic alkaline secondary batteries used as a group.

[0067]

As described above, according to the present invention, the positive electrode for an alkaline secondary battery, which can improve the welding strength between the current collector and the conductive substrate and improve the active material utilization of the positive electrode, An alkaline secondary battery can be provided. Also,
ADVANTAGE OF THE INVENTION According to the manufacturing method of the positive electrode for alkaline secondary batteries which concerns on this invention, the welding strength of a collector and a conductive substrate is improved, and the positive electrode which can improve the active material utilization rate is manufactured with good productivity. It has remarkable effects such as being able to perform.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a positive electrode for an alkaline secondary battery according to the present invention.

FIG. 2 is a cross-sectional view obtained when the current collector of the positive electrode in FIG. 1 is cut along a short side direction.

FIG. 3 is a cross-sectional view for explaining a step of resistance welding a current collector to a conductive substrate.

FIG. 4 is a partially cutaway perspective view showing a cylindrical alkaline secondary battery as an example of the alkaline secondary battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Current collector welding area (conductive board), 2 ... Positive electrode mixture, 3 ... Current collector, 4 ... Protrusion, 12 ... Positive electrode.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H017 AA02 AS02 BB11 BB14 CC01 CC25 DD01 EE00 EE04 HH01 HH04 5H022 AA04 BB16 BB22 CC13 CC23 EE03 5H050 AA14 BA14 CA03 CB16 DA02 DA06 FA15 GA07 GA12 HA07

Claims (4)

[Claims] 1. An alkaline battery comprising: a conductive substrate having a three-dimensional structure; a current collector to be resistance-welded to the conductive substrate; and a positive electrode mixture held on the conductive substrate and containing an active material. In the positive electrode for a secondary battery, the current collector has a plurality of protrusions, and the total area occupied by each of the protrusions is within a range of 10 to 60% of the facing area between the current collector and the conductive substrate. A positive electrode for an alkaline secondary battery. 2. The positive electrode for an alkaline secondary battery according to claim 1, wherein the number of the protrusions is in a range of 1 to 10. 3. A positive electrode comprising a conductive substrate having a three-dimensional structure, a current collector to be resistance-welded to the conductive substrate, and a positive electrode mixture held by the conductive substrate and containing an active material. In the alkaline secondary battery including the negative electrode, the current collector has a plurality of protrusions, and the total area occupied by each of the protrusions is 10 to 10 of the facing area between the current collector and the conductive substrate. An alkaline secondary battery characterized by being within a range of 60%. 4. A step of holding a positive electrode mixture containing an active material on a conductive substrate having a three-dimensional structure, and removing a part of the positive electrode mixture by ultrasonic vibration to form a positive electrode on the conductive substrate. Forming a mixture non-holding region, and resistance welding a current collector to the positive electrode mixture non-holding region of the conductive substrate, wherein the current collector has a plurality of protrusions, A method for manufacturing a positive electrode for an alkaline secondary battery, wherein the total area occupied by each protrusion is within a range of 10 to 60% of an area of the current collector and the positive electrode mixture non-holding area.