JPH11213991A - Manufacture of electrode for winding battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate multiple cracks without generating chamber by passing an electrode raw material between a first roller and a roller group including at least one metal back-up roller arranged in both sides of a second roller, and pushing the second roller to the first roller. SOLUTION: A crack generating mechanism 1 is formed of first rollers 4 and roller groups 7 respectively including a second roller 5 and metal back-up rollers 6 arranged in both sides of the second roller 5. The first roller 4 is formed by coating a peripheral surface of a metal core 2 with a rubber layer 3, and the second roller 5 made of metal is arranged opposite to the first roller 4. The first roller and the roller group 7 form one unit, and plural units, for example, three units are arranged so that the first and the second rollers 4, 5 are positioned each other and so as to be rotated reversely to each other. An electrode raw material is pinched by two belt conveyors, and passed through the first rollers and the roller groups 7, and the second roller 5 is pushed to the first roller 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrode for a wound battery.

[0002]

2. Description of the Related Art In a spiral electrode group housed in a battery container, there are several conditions for satisfactorily winding a sheet comprising a positive electrode, a separator and a negative electrode. The electrode has flexibility.

[0003] By imparting flexibility to the electrode, the number of bent portions of the electrode at the time of winding increases, and the bending angle becomes obtuse. For this reason, when a three-dimensional substrate such as a felt-like porous metal body made of metal fibers is used as the conductive substrate filled with the active material, the fibers can be prevented from projecting in a whisker-like manner, and an internal short circuit Can be prevented. In addition, since the adhesion between the positive electrode and the negative electrode arranged with the separator interposed therebetween is improved, efficient gas exchange can be achieved.

[0004] For this reason, Japanese Patent Laid-Open Publication No.
Japanese Patent Publication No. 02-302, encloses a long electrode material in which a conductive substrate is filled with an active material between two belt conveyors, and passes the electrode material between a plurality of rollers arranged vertically displaced from each other. It is described that a material is bent between the plurality of rollers to form fine cracks to produce an electrode. However, such a method has a problem that a sufficient number of cracks cannot always be formed.

In Japanese Patent Application Laid-Open No. 5-41209, a long electrode material filled with an active material on a conductive substrate is passed between a rubber roller and a metal roller which are arranged opposite to each other, and the metal roller is moved. It is described that a fine crack is formed in the electrode material by pressing the electrode material toward the electrode material to produce an electrode.

[0006]

However, even with the method described in Japanese Patent Application Laid-Open No. 5-41209, it is not always possible to form a sufficient number of cracks. If the pressing force of the rubber roller and the metal roller to be pressed becomes non-uniform, there is a problem that the obtained electrode is warped. An object of the present invention is to provide a method of manufacturing an electrode for a wound battery in which a large number of cracks are formed without causing warpage.

[0007]

According to the present invention, there is provided a method for manufacturing an electrode for a wound type battery, comprising: a step of sandwiching an electrode material having a conductive substrate filled with an active material between two belt conveyors;
It includes a first roller having an outer peripheral surface made of at least rubber, a second roller made of metal disposed opposite to the first roller, and at least one metal backup roller arranged on both sides of the second roller. A roller group and a crack generating means, wherein the electrode material sandwiched by the bell conveyor between the first roller and the roller group of the generating means is passed, and the second roller is connected to the first roller. Forming fine cracks in the electrode material by pressing toward the electrode material.

Preferably, the electrode material has a final product size. A structure in which the crack generating means includes the first roller and the roller group as one unit, and a plurality of the units are arranged such that the first and second roller positions are alternately reversed around the belt conveyor. It is preferable to have

The first roller has a diameter of 60 in which a metal shaft is covered with a rubber layer having a Vickers hardness of 30 to 70 °.
And the second roller has a diameter of 1 mm.
It is preferably from 0 to 30 mm.

[0010] The second roller in the crack generation means and at least one backup roller arranged on both sides of the second roller are arranged within a range of a side length in a longitudinal direction of the electrode material having the final product dimensions. Is preferred.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of manufacturing an electrode for a wound type battery according to the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the crack generating mechanism 1 includes a first roller 4 having an outer peripheral surface of a metal shaft core 2 covered with a rubber layer 3 and having at least an outer peripheral surface made of rubber. Roller 5 made of metal arranged at least and metal backup roller 6 arranged at least one (for example, one) on both sides of this second roller 5
And a roller group 7 including the above as one unit, and a plurality of units, for example, three units are arranged such that the positions of the first and second rollers 4 and 5 are alternately reversed.

An electrode material 8 in which a conductive substrate is filled with an active material is sandwiched between two belt conveyors 9a and 9b and passes between the first roller 4 and the roller group 7 of the generating mechanism 1. And the second roller 5 of the roller group 7
Is pressed toward the first roller 4 to form fine cracks in the electrode material 8 to manufacture a wound battery electrode.

The electrode material is, for example, as follows (1)
A positive electrode material and (2) a negative electrode material are used. This electrode material preferably has a shape of the final product dimensions. (1) Positive electrode material This positive electrode material is prepared by adding a conductive material to a nickel compound powder such as nickel hydroxide and kneading it with a binder and water to prepare a paste. It is manufactured by filling the substrate with the original structure, drying and molding.

As the nickel compound, for example, nickel hydroxide can be used. In this nickel hydroxide, Co, Cu, Zn, Al, Mn, Ca, M
Allows co-precipitation of metals such as g, Fe, Si.

Examples of the conductive material include metal cobalt, cobalt oxide, and cobalt hydroxide. Examples of the binder include carboxymethyl cellulose, methyl cellulose, sodium polyacrylate, polytetrafluoroethylene, and the like.

Examples of the porous metal include sponge, fiber, and felt. (2) Negative electrode material This negative electrode material is prepared by adding a conductive material to, for example, a hydrogen storage alloy powder, kneading the mixture with a binder and water to prepare a paste, filling the paste into a conductive substrate, and drying the paste.
It is produced by molding.

The hydrogen storage alloy is not particularly limited as long as it can store hydrogen electrochemically generated in an electrolytic solution and can easily release the stored hydrogen during discharge. . As this hydrogen storage alloy,
For example LaNi _5, MmNi ₅ (Mm; misch metal), LmNi ₅ (Lm; lanthanum enriched misch metal), or some of these Ni Al, Mn, C
o, Ti, Cu, Zn, Zr, Cr, B, etc.
e-type ones can be mentioned. Among them, the general formula Lm
Ni _x Mn _y A _z (However, A is shown Al, at least one metal selected from Co, the atomic ratio x, y, z is the total value of 4.8 ≦ x + y + z ≦ 5.4) is represented by It is preferable to use one.

Examples of the binder include those similar to those used for the positive electrode material. As the conductive material, for example, carbon black or the like can be used.

Examples of the conductive substrate include a two-dimensional substrate such as a punched metal, an expanded metal, a perforated rigid plate, and a nickel net, and a three-dimensional substrate such as a felt-like metal porous body and a sponge-like metal substrate. be able to.

The belt conveyor protects the surface of the electrode material when cracks are formed, and also functions to prevent meandering. The first roller generates a large number of cracks in the electrode material sandwiched by the belt conveyor passing between the rollers by bending the rubber layer on the surface under the pressing force from the second roller made of metal. It has the effect of causing.

The rubber layer on the surface of the first roller preferably has a Vickers hardness of 30 to 70 °. Examples of the rubber having such Vickers hardness include nitrile butyl. When the Vickers hardness of the rubber layer is less than 30 °, the rubber layer becomes too hard to bend easily, and it becomes difficult to generate a sufficient number of cracks in the electrode material. On the other hand, when the Vickers hardness of the rubber layer exceeds 70 °, the crack depth to the electrode material becomes too small and the active material on the surface may fall off. More preferably, the Vickers hardness of the rubber layer of the first roller is 40 to 60 °.

The first roller has a diameter of 60 to 120 m.
It preferably has a dimension of m. When the diameter of the first roller is less than 60 mm, the degree of bending when pressing from the second roller is small, and it becomes difficult to generate a sufficient number of cracks in the electrode material. On the other hand, when the diameter of the first roller exceeds 120 mm, there is a possibility that a sufficient gap between the rollers cannot be obtained when a plurality of the first rollers are arranged. More preferably, the diameter of the first roller is 80 to 100 mm.

The second roller is used to generate a crack in the electrode material held by the belt conveyor by pressing the second roller toward the first roller with the belt conveyor interposed therebetween. The pressing force of this second roller is
The degree of deflection of the rubber layer of the first roller is 1 to 20 kgf /
cm ² is preferably set. The second roller is made of, for example, stainless steel, iron, or the like.

The second roller has a diameter of 10 to 30 mm.
It is preferred that The diameter of the second roller is 10 m
If it is less than m, it becomes difficult to generate a sufficient number of cracks in the electrode material. On the other hand, if the diameter of the second roller exceeds 30 mm, the crack depth in the electrode material becomes shallow, and the active material on the surface may fall off. More preferably, the diameter of the second roller is 15 to 25 mm.

The backup rollers arranged on both sides of the second roller are capable of reducing the warpage of the electrode material when the electrode material sandwiched between the first and second rollers by the belt conveyor generates minute cracks. In addition to the suppression, the repulsive force at the time of this correction serves to generate cracks in the electrode material. This backup roller is
Preferably, the second roller has a diameter similar to that of the second roller.
This backup roller has one side on both sides of the second roller.
Not only books but also two or more books may be arranged.

The second roller and at least one backup roller arranged on both sides of the second roller,
It is preferable that the electrode material is arranged within the range of the side length in the longitudinal direction of the electrode material having the final product dimensions. With such an arrangement, the function of the backup roller described above can be effectively applied to the electrode material.

The crack generating mechanism may be constituted by one unit, but is preferably constituted by a plurality of units from the viewpoint of forming a large number of cracks in the electrode material. When a crack generation mechanism is constituted by a plurality of units, it is preferable to arrange an odd number of such units, such as 3, 5, and 7, from the viewpoint of generating minute cracks in the electrode material.

As described above, according to the present invention, the first roller whose outer peripheral surface is made of at least rubber, the second roller made of metal disposed opposite to the first roller, and both sides of this second roller And a roller group including at least one metal backup roller arranged in each of the above, constitutes a crack generation mechanism, is sandwiched between two bell conveyors, and the electrode material having a structure in which an active material is filled in a conductive substrate is provided. By passing between the first roller and the roller group of the generating mechanism and pressing the second roller toward the first roller, a large number of fine cracks can be generated without warpage of the electrode material. Can be generated.

That is, the electrode material sandwiched between the two belt conveyors is passed between the first roller of the crack generating mechanism and the roller group, and the second roller of the roller group is pressed toward the first roller. By doing so, the rubber layer on the surface of the first roller bends following the pressing force of the second roller, so that many fine cracks can be generated in the electrode material located between these rollers. At this time, a curling force acts on the electrode material portions located on both sides of the second roller as a center, but by arranging backup rollers on both sides of the second roller, the curling force is suppressed and the repulsive force is reduced. Thereby, a crack can be generated in the electrode material. Therefore, an electrode having many fine cracks can be manufactured.

In particular, the first roller constituting the crack generating mechanism has a Vickers hardness of 30 on the metal shaft center.
60-120mm diameter covered with ~ 70 ° rubber layer
By using the second roller having a diameter of 10 to 30 mm as the second roller, an electrode having a larger number of fine cracks can be manufactured.

Further, a first roller having an outer peripheral surface made of at least rubber, a second roller made of a metal disposed opposite to the first roller, and at least one metal arranged on both sides of the second roller, respectively. And a roller group including a backup roller made of a single roller, and a crack generating mechanism having a structure in which a plurality of such units are arranged so that the positions of the first and second rollers are alternately reversed. An electrode having fine cracks can be manufactured.

Therefore, since the electrode obtained by the method of the present invention has high flexibility in which a large number of fine cracks are generated, the bent portion of the electrode when the electrode is overlapped and wound with a separator interposed therebetween is formed. The bending angle becomes obtuse. As a result, when a three-dimensional substrate such as a felt-like metal porous body made of metal fibers is used as the conductive substrate filled with the active material, the fibers can be prevented from projecting in a whisker-like manner. Short circuit can be prevented. Further, since the adhesion between the electrode and the counter electrode arranged with the separator interposed therebetween is improved, efficient gas exchange can be achieved.

When the electrode material is supplied to the crack generating mechanism, the surface of the electrode material can be protected by being sandwiched between two belt conveyors in advance.
Meandering can be prevented. In addition, the electrode material can be supplied to the crack generating mechanism in the form of final product dimensions by being sandwiched between two belt conveyors. As a result, the electrode obtained after passing through the generation mechanism can be used for battery assembly as it is, and furthermore, it is possible to avoid a problem such as falling off of an active material caused by cutting to a product size after generating a crack. Can be.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. Example 1 <Preparation of Paste-Type Positive Electrode> A mixed powder consisting of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was mixed with 0.3 parts by weight of carboxymethylcellulose with respect to the nickel hydroxide powder, and A paste is prepared by adding 0.5 parts by weight of a suspension of tetrafluoroethylene (specific gravity: 1.5, solid content: 60% by weight) in terms of solid content, adding 45 parts by weight of pure water thereto, and kneading. did. Subsequently, this paste was filled in a nickel-plated fiber substrate, the paste was further applied to both surfaces thereof, dried, rolled by roller pressing, and then cut to obtain a 127.0 mm × 61.5 mm. A paste-type positive electrode material having the final product dimensions was produced.

Next, as shown in FIG. 1 and FIG.
m, and is passed between the first roller 4 and the roller group 7 of the crack generating mechanism 1 composed of three units while being sandwiched between two belt conveyors 9a and 9b having a width of 150 mm.
A positive electrode was manufactured by pressing the second roller 5 of the roller group 7 toward the first roller 4 to generate cracks in the positive electrode material 8.

The first roller 4 has a diameter of 84 mm in which a metal shaft 2 is covered with a rubber layer 3 of 18 mm in thickness made of nitrile butyl rubber having a Vickers hardness of 40 °.
mm. Each of the second roller 5 and the backup roller 6 has a diameter of 15 mm.
Of stainless steel was used. The pressing force from the second roller 5 to the first roller 4 in the unit located in the middle of the generating mechanism 1 was set to 5 kgf / cm ² . Further, the supply speed of the positive electrode material 8 held between the belt conveyors 9a and 9b to the generating mechanism 1 is 980.
cm / min.

Example 2 A positive electrode was manufactured in the same manner as in Example 1 except that the pressing force from the second roller 5 to the first roller 4 was set to 10 kgf / cm ² .

(Comparative Example 1) A paste was filled in a nickel-plated fiber substrate in the same manner as in Example 1 above, the paste was further applied to both surfaces, dried, and rolled by roller pressing. A long cathode material was produced.

Next, as shown in FIG. 3, the long positive electrode material 11 is a first roller having a diameter of 84 mm and a steel shaft center 12 covered with a rubber layer 13 having a thickness of 18 mm made of nitrile butyl rubber having a Vickers hardness of 40 °. 14 and this roller 1
4 is supplied at a speed of 980 cm / min between the second rollers 15 made of stainless steel having a diameter of 15 mm, and the pressing force from the second rollers 15 to the first rollers 14 is 5 kgf / cm. ^After setting fine cracks in the long positive electrode material 11 by setting to ² , the positive electrode was manufactured by cutting to the final product dimensions.

Comparative Example 2 A positive electrode was manufactured in the same manner as in Comparative Example 1 except that the pressing force from the second roller 15 to the first roller 14 was set to 10 kgf / cm ² .

The obtained Examples 1 and 2 and Comparative Examples 1 and 2
The positive electrode was measured for flexibility and the number of cracks generated. The results are shown in Table 1 below. The flexibility is such that two support jigs are arranged at an interval of 60 cm, and the positive electrode is placed on these jigs.
It was determined by measuring the bending depth of the positive electrode when a load of gf was applied.

[0042]

[Table 1]

As is apparent from Table 1, Examples 1 and 2 were used.
It can be seen that the number of cracks generated in the positive electrode obtained by the method was larger than that of the positive electrodes of Comparative Examples 1 and 2, and that the positive electrode had good flexibility.

The positive electrodes of Examples 1 and 2 and Comparative Examples 1 and 2 were respectively wrapped with separators made of a nonwoven fabric of polypropylene resin fibers, and these were overlapped with a negative electrode manufactured by the following method. By turning, each electrode group was produced. An AA-size cylindrical nickel-metal hydride battery was assembled by storing these electrode groups and an electrolytic solution comprising 7N KOH and 1N LiOH in a cylindrical container having a bottom.

<Preparation of Paste-Type Negative Electrode> Commercially available lanthanum-enriched misch metal Lm and Ni, Co, Mn,
LmNi _4.0 Co _0.4
A hydrogen storage alloy having a composition of Mn _0.3 Al _0.3 was produced. The hydrogen storage alloy was mechanically pulverized and passed through a 200-mesh sieve. 0.5 parts by weight of sodium polyacrylate with respect to 100 parts by weight of the obtained alloy powder,
0.125 parts by weight of carboxymethylcellulose (CMC), 2.5 parts by weight of polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60 wt%) and 1.0 part by weight of carbon powder as a conductive material and 50 parts by weight of water A paste was prepared by mixing with This paste was applied to punched metal, dried, molded under pressure, and then cut into final product dimensions to produce a paste-type negative electrode.

Each of the 1000 storage batteries of Examples 1 and 2 and Comparative Examples 1 and 2 was prepared, and the short-circuit failure rate of these storage batteries was examined. The results are shown in Table 2 below. Table 2 below also shows the flexibility of the positive electrode incorporated in the storage battery.

[0047]

[Table 2]

As is apparent from Table 2, Examples 1 and 2 were used.
It can be seen that the storage batteries incorporating the positive electrodes of Comparative Examples 1 and 2 have a significantly lower short-circuit failure rate than the storage batteries incorporating the positive electrodes of Comparative Examples 1 and 2.

[0049]

As described in detail above, according to the present invention, it is possible to manufacture an electrode for a wound type battery in which a large number of cracks are formed without causing warpage. Accordingly, there is a remarkable effect such that an internal short circuit does not occur and a spiral electrode group capable of performing efficient gas exchange can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an apparatus used for manufacturing an electrode for a wound battery according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of the apparatus of FIG.

FIG. 3 is a cross-sectional view showing an apparatus used for manufacturing a conventional wound battery electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Crack generation mechanism, 3 ... Rubber layer, 4 ... 1st roller, 5 ... 2nd roller, 6 ... Backup roller, 8 ... Electrode material, 9a, 9b ... Belt conveyor.

Claims (5)

[Claims] An electrode material having a conductive substrate filled with an active material sandwiched between two belt conveyors; a first roller having an outer peripheral surface made of at least rubber; and a first roller facing the first roller. And a roller group including at least one metal backup roller arranged on both sides of the second roller. The first roller and the first roller of this generating means Forming a fine crack in the electrode material by pressing the second roller toward the first roller while passing the electrode material held between the roller groups by the belt conveyor. A method for manufacturing a wound battery electrode. 2. The method according to claim 1, wherein the electrode material has a final product dimension. 3. The crack generating means sets the first roller and the roller group as one unit, and causes the first and second roller positions to be alternately reversed around the electrode material. The method for manufacturing an electrode for a wound battery according to claim 1, wherein the electrode has a structure in which a plurality of electrodes are arranged. 4. The first roller has a diameter of 6 in which a metal shaft center is covered with a rubber layer having a Vickers hardness of 30 to 70 °.
The method of claim 1, wherein the second roller has a diameter of 10 to 30 mm, and the second roller has a diameter of 10 to 30 mm. 5. The method according to claim 1, wherein
3. The roller and at least one backup roller arranged on both sides of the roller are arranged within a range of a side length in a longitudinal direction of the electrode material having the final product size. 4. A method for producing an electrode for a wound battery according to the above.