JPH0888006A - Electrode support body for battery, its manufacture, and use of electrode supporting body for battery - Google Patents

Abstract

PURPOSE: To provide an electrode support body preferable to manufacture a battery by aiming at the surface property of the electrode support body made of a metal porous body and provide the electrode support body capable of giving better characteristics to the battery. CONSTITUTION: An electrode supporting body 30 for a battery is made of a porous sheet in which metal fibrous bodies 20 are three-dimensionally connected. A degree of the connection of the metal fibrous bodies 20 is different on the surface 21a and the back surface 21b of the sheet, and on the surface 21a, a degree of the connection is low and napped metal fibrous bodies are long. On the back surface 21b, a degree of the connection is high and napped metal fibrous bodies are short. An active material is filled in the electrode supporting body with a such surface property to form an electrode for the battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery electrode support comprising a porous metal body and a method for producing the same, and further to a method for using the electrode support in the production of a battery.

[0002]

2. Description of the Related Art In recent years, high capacity nickel-cadmium (Ni-C) has been used as a power source for various electronic devices, especially portable devices.
d) Attention is paid to alkaline storage batteries such as batteries and nickel-hydrogen (Ni-NH) batteries. Conventionally, a sintered substrate obtained by sintering Ni powder has been used for the positive electrode of an alkaline storage battery. However, since this substrate has a small porosity of 80%, in recent years, a high capacity battery has a large porosity of 95%, and a metal foam or metal nonwoven fabric having three-dimensional continuous pores is used as an electrode support. ing.

The foam metal is, for example, Japanese Patent Publication No. 57-393.
As disclosed in Japanese Patent Publication No. 17, a carbon powder is applied to a base material such as urethane foam, electroplating called drum plating is performed, and then normal electroplating is performed.
It was obtained by removing the base material by heating. Further, as disclosed in JP-A-61-76686, there is also a method of forming a metal film on a base material by a vapor phase method, performing electroplating, and then removing the base material. Recently, a method has also been used in which after electroless plating is applied to a base material, electroplating is further performed to remove the base material to obtain an electrode support.

A battery electrode can be formed by coating and filling an active material on the metal porous body thus obtained. When the obtained electrode and the counter electrode and the separator are wound to form a battery, for example, the properties of the electrode surface in contact with the separator are considered to affect the characteristics of the battery. However, the relationship between the characteristics of the electrode surface of the electrode support and the characteristics of the battery has not been studied in detail.

[0005]

An object of the present invention is to provide a preferable electrode support for battery production, focusing on the surface properties of the electrode support made of a metal porous body, and to provide the battery with more excellent characteristics. It is to provide an electrode support that can be applied.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have paid attention to the fact that the surface property of a sheet-shaped electrode support made of a metal porous material is changed between a pair of opposed surfaces, that is, a front surface and a back surface. The present invention has been created.

The battery electrode support according to the present invention is a support for filling an active material to form a battery electrode, and is a porous material formed by three-dimensionally joining metal fibrous bodies. The sheet is made of a sheet, and the front surface and the back surface of the sheet have different degrees of bonding of the metal fibrous bodies. The degree of bonding is small on one surface and the fluffy metal fiber bodies are long, and the other surface is bonded. Is characterized by a high degree and short fluffy metal fibrous bodies.

In the method of manufacturing an electrode support according to the present invention, a sheet-like porous non-woven fabric in which organic polymer fibers are three-dimensionally joined is plated, and the plated non-woven fabric is heat-treated. After removing the non-woven fabric, a step of obtaining a metal porous body by plating as an electrode support is provided. In this method, the sheet-shaped nonwoven fabric used has different degrees of bonding of the organic polymer fibers on the front surface and the back surface, the degree of bonding is low on one surface and the fluffing organic polymer fibers are long, and on the other surface. It is characterized by high degree of bonding and short fluffy organic polymer fibers.

In the manufacturing method according to the present invention, a nonwoven fabric made of polyethylene or polypropylene can be used as the nonwoven fabric made of organic polymer fibers. The non-woven fabric is a sheet-like product obtained by arranging organic polymer fibers in a web-like or mat-like manner by an appropriate method and joining the fibers by an adhesive or fusion of the fibers themselves. For example, in the dry method, the organic polymer fibers are applied to a cotton-opening machine or a cotton-mixing machine, and then a web is made by a carding machine or a garnet machine. Can be obtained.
At this time, the nonwoven fabric used in the method of the present invention can be obtained by changing the bonding degree of the fibers on the front surface and the back surface of the sheet-shaped web. Therefore, as shown in FIG. 1, for example, after the web 1 is dipped in the adhesive (binder) liquid 2, the taken-out web 1 is left for an appropriate time, and the adhesive is applied in the direction of gravity (indicated by arrow G). Just move it. The movement of the adhesive reduces the amount of the adhesive on the surface 1a, and when the adhesive is cured, the degree of bonding of the fibers is reduced, so that longer fibers become fluffed. On the other hand, on the back surface 1b, the amount of the adhesive is large, and when it is cured, the degree of bonding of the fibers is large, and the fluffy fibers are small and short. Further, as shown in FIG. 2, the nonwoven fabric is continuously manufactured. In this case, for example, the sheet 11 taken out after being immersed in the binder tank 12
With respect to the above, the effect described above can be obtained by appropriately providing the time for the binder to move in the direction of gravity (indicated by the arrow G). Further, the existing amount of the adhesive on the front surface and the back surface may be changed by a forced force such as suction. By drying and curing the adhesive with different amounts of adhesive on the front surface and the back surface in this way, a surface with a low degree of bonding and long fluffy fibers can be obtained, and a high degree of bonding on the back surface. And a short surface of fluffy fibers is obtained. By using a nonwoven fabric having such a surface texture, it is possible to obtain a metal porous body having a similar surface texture according to the process described below.

The metal porous body can be formed, for example, as follows. For example, electroless plating is performed after electroless plating is applied to the base material to impart conductivity,
Then, the base material is decomposed and removed to obtain a metal porous body by plating. Further, by coating the base material with carbon to impart conductivity, electroplating is performed, and then the base material is decomposed and removed to obtain a metal porous body by plating. Furthermore, a metal is vapor-deposited on the substrate by sputtering or the like to give conductivity, and then electroplating is performed,
Then, the base material is decomposed and removed to obtain a porous metal body.

For electroless plating, electroless nickel plating using, for example, hypophosphorous acid or a boron compound as a reducing agent is used. Examples of boron compounds include boron hydride compounds and dimethylamine borane. In electroless plating, for example, a Pd / Sn catalyst is adsorbed on the nonwoven fabric, the catalyst is activated, and then the nonwoven fabric is immersed in a plating solution containing nickel and a reducing agent. After such electroless nickel plating, electric nickel plating can be performed for the purpose of adjusting the plating weight. The non-woven fabric can be decomposed and removed, for example, by heat treatment in an oxygen atmosphere. Then, the obtained metal porous body is heat-treated in a reducing atmosphere such as hydrogen to obtain a metal porous body as a current collector. The obtained metal porous body reflects the fiber structure of the nonwoven fabric used,
It is a porous sheet in which metallic fibrous bodies are three-dimensionally joined. Then, the front surface and the back surface of the sheet, the degree of bonding of the metal fibrous body is different, the degree of bonding is small on one surface and fluffy metal fibrous body is long, the degree of bonding on the other surface. Short and tall and fluffy metal fibrous bodies.

To form electrodes, the obtained metal porous body as a current collector is filled with an active material. As the active material, for example, in the case of an alkaline storage battery using a porous metal body made of nickel, a mixture containing nickel hydroxide as a main component is used. Other components in the mixture include, for example, 3 to 15% by weight of cobalt, 1 to 5% by weight of cobalt hydroxide, and 1 to 5% by weight of zinc oxide. In addition, a binder or the like formed by adding polyvinyl alcohol, carboxymethyl cellulose or the like to water may be used. The formed electrode is wound together with the counter electrode and the separator to form a battery. The electrode support of the present invention is applied to the production of alkaline storage batteries such as nickel-cadmium batteries and nickel-hydrogen batteries.

According to the process described above, a method of using the support for electrodes can be provided according to the present invention. A first method of use according to the present invention is to form a battery by stacking a process of filling an electrode support for a battery with an active material to obtain an electrode, stacking the obtained electrode, a prepared counter electrode and a separator on top of each other. In the winding step, the degree of bonding of the metal fibrous bodies is low, and the fluffed metal fibrous bodies are long, and the surface side of the electrode support is inwardly wound. To do. On the other hand, a second method of use according to the present invention is a step of filling a battery electrode support with an active material to obtain an electrode, stacking the obtained electrode, a counter electrode and a separator prepared further and winding the battery. In the winding step, the degree of bonding of the metal fibrous bodies is high and the fluffy metal fibrous bodies are short, and the surface side of the electrode support is wound inside. To do.

[0014]

In the electrode support of the present invention, the surface of the metal support having a low degree of bonding and long fluffing is more flexible. Therefore, when this surface is wound inside, the fibers on that surface are well along the separator and can make good contact.
By winding with this surface inside, the electrode and the separator can be well overlapped and wound, and a short circuit in which the electrode support pierces the separator and contacts the counter electrode is more effectively prevented.

On the other hand, when the metal fibers are more densely bonded and the surface with less fluffing is wound inward, the surface where the bonding of the metal fibers is low and the surface with long fluffing of the metal fibers is outside is wound. It is possible to flexibly cope with tensile strain that sometimes occurs on the outside, and it is possible to suppress disconnection of the metal fiber. Therefore, it is considered that the utilization rate of the active material is improved during charging and discharging. In this way, when the metal fibers are more closely joined and the surface side with less fluff is inwardly wound,
It is considered that the utilization rate of the active material is further improved.

[0016]

【Example】

Example 1 A nonwoven fabric having a basis weight of 60 g / m ² and a thickness of 2.5 mm was obtained by forming a polyester fiber having a wire diameter of 18 μm into a web by a dry method, immersing the web in an epoxy emulsion, drying and curing the web. In this process, as the epoxy emulsion was dried, gravity transferred the adhesive from the front side to the back side as described above, forming a low-adhesive surface and a high-adhesive back surface. By drying and curing this, a sheet-like nonwoven fabric having a long surface with many fluffy fibers and a back surface with few fluffy fibers was obtained. Next, a colloidal catalyst composed of palladium chloride and tin chloride was adsorbed on the non-woven fabric. After removing Sn by sulfuric acid and activating the catalyst, nickel electroless plating was performed. The plating weight at this time was 20 g / m ² . Next, electroless nickel plating was applied on the non-woven fabric. The plated porous body was thoroughly washed with water, dried, and then heated in air at 600 ° C. to thermally decompose and remove the nonwoven fabric.
Then, heat treatment was performed at 1000 ° C. in a reducing atmosphere containing hydrogen to obtain a nonwoven fabric made of nickel as a current collector. The obtained metal nonwoven fabric has the same fibrous structure as the polyester nonwoven fabric used, the degree of bonding of the metal fibers is different between the front surface and the back surface, and the degree of bonding is small and fluffy on the surface. Was long, the degree of bonding was high on the back surface, and there were few and short fluffy metal fibers.

The resulting metallic nonwoven fabric was cut out and used as an electrode support. An electrode support made of a metal nonwoven fabric was filled with a paste-like active material containing nickel hydroxide as a main component and pressed to obtain a positive electrode plate for an alkaline storage battery. The obtained positive electrode plate, a negative electrode using a hydrogen storage alloy, and a polypropylene nonwoven fabric separator were wound together to produce an AA-type nickel-hydrogen battery. When winding, the surface side having the long fluffy metal fibers was placed inside.

Comparative Example 1 On the other hand, a polyester fiber having a wire diameter of 18 μm was formed into a web by a dry method, dipped in an epoxy emulsion, dried and cured to obtain a nonwoven fabric having a basis weight of 60 g / m ² and a thickness of 2.5 mm. In this process, the epoxy emulsion was forcibly and quickly dried and cured, and the distribution of the adhesive was made the same on the front surface and the back surface to obtain a nonwoven fabric. The surface properties of the obtained nonwoven fabric were almost the same on the front surface and the back surface.
Using the obtained nonwoven fabric, a metallic nonwoven fabric was prepared in the same manner as in Example 1, and then an active material was filled to form an electrode.
A AA nickel-hydrogen battery was produced in the same manner as in.

As a result of Example 1 and Comparative Example 1, Example 1
Then, although the short circuit was 0 in 100 manufactured batteries,
In Comparative Example 1, 5 out of 100 short circuits occurred.

Example 2 A metallic nonwoven fabric was obtained in the same manner as in Example 1. The obtained metallic nonwoven fabric was filled with a paste-like active material containing nickel hydroxide as a main component and pressed to obtain a positive electrode plate for an alkaline storage battery. The obtained positive electrode plate, a negative electrode using a hydrogen storage alloy, and a polypropylene nonwoven fabric separator were wound together to produce an AA-type nickel-hydrogen battery. In winding, the back side of the porous metal body having a small number of fluffy metal fibers and being short was wound inside.

Comparative Example 2 A metallic nonwoven fabric was prepared in the same manner as in Comparative Example 1 to obtain a battery.

As a result of Example 2 and Comparative Example 2, the utilization rate of the active material at the 10th cycle of charging / discharging was 95% in Example 2 and 92% in Comparative Example 2. The utilization rate was calculated as a percentage of the actual discharge capacity with respect to the theoretical value of the discharge capacity per 1 g of the active material.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing one specific example of a process for producing an organic polymer fiber nonwoven fabric having different properties on the front surface and the back surface in the present invention.

FIG. 2 is a schematic view showing another specific example of the process for producing an organic polymer fiber nonwoven fabric having different properties on the front surface and the back surface in the present invention.

FIG. 3 is a cross-sectional view schematically showing the surface texture of the battery electrode support according to the present invention. In the sheet-shaped electrode support 30 in which the metal fibers 20 are three-dimensionally joined, the surface 2
In 1a, the degree of fiber bonding is lower than that of the back surface 21b, and the number of fluffy fibers is longer and longer than that of the back surface 21b.
On the other hand, on the back surface 21b, the degree of fiber bonding is
higher than a, the fluffy fibers are less and shorter than the surface 21a.

[Explanation of symbols]

 1 web 2 adhesive liquid 1a front surface 1b back surface

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akihisa Hosoe 1-3-1 Shimaya, Konohana Ward, Osaka No. 1 Itami Works, Sumitomo Electric Industries, Ltd.

Claims (4)

[Claims] 1. An electrode support for filling an active material to form a battery electrode, comprising a porous sheet formed by three-dimensionally joining metal fibrous bodies, The front surface and the back surface, the degree of bonding of the metal fibrous body is different, the degree of bonding is small on one surface and fluffy metal fibrous body is long, the degree of bonding on the other surface. An electrode support for a battery, which is characterized by a short, high and fluffy metallic fibrous body. 2. A method of manufacturing an electrode support for filling a battery electrode with an active material, comprising plating a sheet-like porous non-woven fabric in which organic polymer fibers are three-dimensionally joined. And a step of applying a heat treatment to the plated non-woven fabric to remove the non-woven fabric, and then obtaining a metal porous body by the plating as the electrode support, in the front and back of the sheet-shaped non-woven fabric, The degree of bonding of the organic polymer fibers is different, the degree of bonding is low and the fluffing organic polymer fibers are long on one surface, and the degree of bonding is high and fluffing organic polymer fibers on the other surface. A method for manufacturing a battery electrode support, characterized in that 3. A method of using the electrode support for a battery according to claim 1, wherein the electrode support for a battery is filled with an active material to obtain an electrode, the obtained electrode, and further preparations are made. And a step of stacking a counter electrode and a separator to form a battery by winding, and in the winding step, the degree of bonding of the metal fibrous bodies is low and the fluffy metal fibrous body is long A method of using an electrode support for a battery, which comprises: 4. A method of using the electrode support for a battery according to claim 1, wherein a step of filling the battery electrode support with an active material to obtain an electrode, the obtained electrode, and a further preparation And a step of stacking a counter electrode and a separator to form a battery by winding, and in the winding step, the degree of bonding of the metal fibrous bodies is high and the fluffy metal fibrous body is short A method of using an electrode support for a battery, which comprises: