JP2001110425A - Current collector body for secondary battery, secondary battery using current collector body, and manufacturing method for the current collector body and the secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method for working a current collector body for an alkaline battery for preventing a porous metallic sintered body from peeling from a metallic core, while working the battery and for strongly bonding the porous metallic sintered body with the metallic core, and to provide a material used for the method. SOLUTION: A strongly bonded body can be obtained by pressurizing and shaping a porous metallic body, having a mean porous diameter of 50 to 200 μm for tightly bonding the same with a metallic core so that the porous metallic body would not easily peel from the metallic core, where a layer of nickel- phosphorus alloy is formed on a surface of the metallic core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current collector for a secondary battery such as a nickel-cadmium or nickel-hydrogen battery, and a secondary battery manufactured using the current collector.

[0002]

2. Description of the Related Art Secondary batteries such as nickel-cadmium or nickel-hydrogen batteries are widely used as power supply batteries, but in recent years, large currents have been taken out due to the increasing use of batteries in various fields. Those that have specifications that can do it are starting to be preferred. In order to achieve this object, it is generally known that it is advantageous to use a substrate using a porous metal sintered body having a large surface area. As a method for producing such a porous metal sintered substrate,
In the early stage of development of this product, nickel powder was pressed and fixed on a core body, which is a punched steel plate with a thickness of 60 to 80 μm and plated with nickel, or a slurry containing nickel powder was applied to a substrate. After being adhered and then sintered, that is, one manufactured by a solid phase sintering method utilizing a solid phase diffusion phenomenon has been used.

[0003] However, the structure in which the porous metal sintered body and the metal core are bonded only by the solid phase diffusion method has insufficient adhesion and the strength of the sintered body itself is inferior. It has been pointed out that there is a problem that the method is easy to perform, and various proposals have been made to improve this point. For example, as measures to improve the strength of the sintered body, metal fibers are arranged around a metal current collector and sintered as proposed in Japanese Patent Application Laid-Open No. 64-24364, There is a method of promoting sintering by providing a layer of cobalt or the like in the vicinity of the current collector as proposed in Japanese Unexamined Patent Publication (Kokai) Publication.

On the other hand, as a measure for improving the adhesion, Japanese Patent Application Laid-Open
A TD nickel plate is used for the current collector as in the proposal of JP-A-130405, and the yttria particles and the nickel particles are brought into contact at the same time, or the surface of the current collector is etched as in the proposal of JP-A-4-162360. By doing
There is a method of roughening the surface of the current collector and increasing the contact area. Furthermore, by forming a boride treatment layer on at least one surface of the current collector steel sheet and using a current collector having a nickel base plating layer having a large number of small-diameter holes, a small amount of liquid phase appears during heat sintering. There is also a method of contributing to improvement in adhesion.

However, the method of arranging metal fibers near the current collector or adding other elements unnecessarily complicates the process, and the method of using etching depends on the method and degree of etching. As a result of the change in the specific surface area, there is a problem that it is difficult to control the etching conditions because the pores of the metal body change. Furthermore, the method of forming a plating layer and bonding it tightly utilizing the formation of a liquid phase based on the melting of a eutectic alloy has the problem that it is difficult to control the sintering temperature conditions and the process becomes complicated.

[0006] On the other hand, there have been many proposals to use a porous metal body as it is as a current collector, but there is a problem in that the porous metal body itself is weak in strength and requires some reinforcement measures. The methods disclosed in JP-A-62-47964 and JP-A-62-90865 are to bond the contact points of the fibers by using a low melting point alloy. The method disclosed in Japanese Patent Application Laid-Open No. Hei 2-274895 is intended to laminate after plating, and the method disclosed in Japanese Patent Application Laid-Open No. 3-130394 and Japanese Patent Application Laid-Open No. The method is to composite and reinforce with a nonwoven fabric when laminating after plating, and the method of JP-A-8-49026 is to reinforce by metal spraying. A. Further, as another proposal, as disclosed in Japanese Patent Application Laid-Open No. 8-222229, after a metal is adhered by electroless plating on urethane foam, pores per unit area of a porous metal body obtained by heat treatment are provided. There is one that limits the number to a certain range.

[0007]

However, when a large number of products such as batteries are manufactured according to a certain standard, the complexity of the manufacturing process undesirably increases the unit price of the product, which is not preferable. Therefore, without complicating the manufacturing process,
A method for improving the strength of the core body by a simpler method and improving the adhesion is required. As a method for solving such a problem, if a separately produced porous metal sheet can be brought into close contact with the substrate, the above problem can be solved.

[0008]

One of the conventional proposals for improving the adhesion between a substrate and a porous material has been a method of performing some processing on the surface of the substrate. However, when processing is performed on the surface of the substrate, there is a problem that the strength of the substrate is degraded although the adhesion is improved. On the other hand, when a special processing method is employed so that the strength of the substrate is not degraded, the processing is difficult. However, there is a problem that the cost for the operation increases. Therefore, in order to solve both of these problems at the same time, it was concluded that instead of processing the surface of the substrate, the state of the contact surface of the porous material with the substrate should be improved. The present invention has been completed.

That is, the present invention relates to a porous metal body mainly composed of nickel or iron, which is a metal element belonging to Group 8 of the periodic table, and having an average pore diameter of 50 to 20 on its surface.
By using a material having a thickness in the range of 0 μm, the adhesion can be improved without any deterioration in substrate strength.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The battery electrode plate of the present invention is obtained by forming a nickel-phosphorus alloy layer on the surface of a core and laminating a sponge metal having an average pore diameter within a certain range, that is, a porous metal molded body. It is characterized in that it is manufactured by pressure-contact molding on a substrate serving as a core. Hereinafter, the present invention will be described in detail with respect to its materials and steps.

1. Core Body As the current collector base used in the present invention, a normal steel plate or a perforated steel plate, that is, a punched steel plate is used. The ordinary steel sheet and the punched steel sheet have a thickness of 25 to 100 μm. However, if a nickel-plated steel sheet is used, the subsequent plating step can be omitted, which is convenient and preferable. In the case of a punched steel plate, a large number of small holes having a diameter of about 1 to 3 mm are formed by subjecting the raw steel plate to physical and chemical processing. As a processing method, a method such as a punching treatment, a chemical etching method, an electrochemical etching method, and a rolling treatment such as a sand blast method or an embossing roll method can be used alone or in combination. Further, a steel sheet having a layer of cadmium, cobalt, nickel or a mixture of these metals formed thereon can also be used.

2. Formation of Alloy Layer on Core Body A nickel-phosphorus alloy layer is formed on a base body serving as a current collector. The reason for forming the nickel-phosphorus alloy layer is that, since this alloy layer is relatively soft, a material having excellent adhesion can be easily formed by pressing a sponge-like metal material having a constant average pore diameter and porosity. Because it can be obtained. The nickel-phosphorus alloy layer is preferably formed by a plating method.
It may be formed by a method or a sputtering method.

Although there are two types of plating, electroplating and electroless plating, it is preferable to use an electroplating method which can simultaneously process a large amount of products in a short processing time. Therefore, for the electroplating, a known Watt bath or sulfamic acid bath can be used, and bright plating, matte plating, semi-glossy plating and the like can be appropriately selected. Plating thickness 0.5 ~
It is preferable that the thickness be in the range of 10 μm. This is because a thickness of 10 μm or more results in excessive quality. An example of the bath composition and electrolysis conditions in the case of electroplating is as follows.

(Example of bath composition formulation) Nickel sulfate 210-270 g / L Nickel chloride 35-55 g / L Boric acid 20-40 g / L Phosphorous acid 15-25 g / L Bath temperature 55-65 ° C pH 1.0 １．５1.5 Current density 10 A / dm ^{2 In} order to improve the adhesion of the nickel-phosphorous alloy layer to the base metal surface, it is preferable that nickel plating be performed prior to nickel-phosphorus alloy plating. is there. The plating conditions in this case may be a well-known Watts bath or sulfamic acid bath, and bright plating, matte plating, semi-glossy plating and the like can be appropriately selected.
Plating thickness is 0.5 to 10 as with nickel-phosphorus plating.
It is preferable to set it in the range of μm.

3. Porous metal body A so-called sponge metal is used as the porous metal body. The method for producing sponge metal is disclosed in Japanese Patent Application Laid-Open No. 57-174484.
And a sintering method disclosed in JP-B-38-17554. In the former, carbon powder or the like is applied to the surface of a skeleton of a foamed resin such as urethane foam. This is a method in which a conductive substance is applied, nickel plating is performed, and then firing is performed to remove combustible organisms such as resin to obtain a porous metal body.

In the latter sintering method, the metal powder is slurried with various polymer resins and solvents, impregnated and applied to the skeleton surface of a foamed resin such as urethane foam, and then fired to fire the metal powder. In addition to sintering, the organic matter is incinerated and removed. Usually, after firing, the sintered metal is reheated in a reducing atmosphere. Hydrogen, ammonia, or the like is used as the reducing atmosphere gas. The average particle size of the metal powder in these methods is preferably 1 to 100 μm.

Examples of the polymer material for impregnation include polystyrene, polymethyl methacrylate, and poly (acrylic acid 2).
-Ethylhexyl), a poly (styrene-acrylic acid) copolymer, polyvinyl butyral, polyvinyl pyrrolidone, or the like is used alone or in combination. As a solvent in this case, for example, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, butyl acetate, Ethyl acetate or water or the like is used alone or in combination.
The mixing of the metal powder, the polymer resin, and the solvent can be performed using a homogenizer, a ball mill, or another mixer. The mixing time can be determined in consideration of the type and particle size of the solvent used, other additives and metal powder.

The porous resin is not limited to urethane foam, but may be polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl acetate / polyvinyl chloride copolymer resin or a cross-linked resin thereof, and in addition to these resins, non-porous resin may be used. A work cloth, a lath-like or punch-like resin net, a glass fiber net, a carbon fiber net, a metal fiber net, or the like can be used alone or in combination. When the metal fibers are applied by impregnating the porous resin with the above-mentioned metal powder slurry, the type of metal fiber used is preferably the same type of metal as the metal powder contained in the slurry. This is because a strong porous body can be formed by sintering. Note that a porous metal body having various pore diameters can be obtained by selecting the firing conditions.

On the other hand, as another method, there is a method in which a metal fiber is used as a raw material to form a block. In this case, the metal fiber used as a raw material is a metal fiber produced by a method such as sampling from a metal block by a vibration cutting method, cutting a metal foil with a rotary blade, extruding a metal oxide paste, cutting from a wire, or the like. ,
Those having a length of 10 to 50 mm are sorted and made into a felt shape by a wet or dry method. Alternatively, a band having a width of 50 to 300 mm, a length of 100 to 500 mm, and a thickness of 2 to 40 mm, in which metal fibers having a diameter of 5 to 100 μm, for example, iron or nickel fibers, are distributed in a mat shape, is produced. Although the strength as a raw material is weak in such a felt or mat state, in the case of the present invention, it can be used as it is because a plated steel sheet is used as a backing.

The porous metal body used in the present invention includes:
Those manufactured by any of the methods described above can be used. The average pore diameter of these metal porous bodies is preferably 50 to 200 μm after being pressed and adhered to the substrate. If the average pore diameter is less than 50 μm, the penetration of the reaction solution becomes insufficient.
If it exceeds μm, the retention of the reaction solution may be insufficient. This is because the strength as the porous metal body is deteriorated.

4. Adhesion between the base body and the porous metal body The base body and the porous metal body are heated to a temperature of about 800 ° C., and are pressed against a roll or a press to make close contact with the substrate to form a current collector. Let it form.

[0022]

The present invention will be described below in more detail with reference to examples. [Examples 1 and 2] An 80 μm-thick ordinary steel plate was used for the substrate core, 2 μm nickel plating was performed under the following conditions, and then a 2 μm nickel-phosphorus alloy plating was performed on the upper layer. The nickel-phosphorus alloy plating film was chemically analyzed by a wet analysis method, and it was confirmed that a phosphorus content was about 10 wt%. [Nickel plating bath composition and plating conditions] Nickel sulfate 300 g / L Nickel chloride 45 g / L Boric acid 30 g / L Bath temperature 50 ° C. pH 4.0 to 4.5 Current density 10 A / dm ²

[Nickel-phosphorus plating bath composition and plating conditions] Nickel sulfate 240 g / L Nickel chloride 45 g / L Boric acid 30 g / L Phosphorous acid 20 g / L Bath temperature 60 ° C. pH 1.0-1.5 Current density 10 A / Dm ²

As the porous metal body, α-iron oxide powder having different average particle diameters is prepared by mixing an acrylic resin solution (50 parts by weight of metal powder and 20 parts by weight of
Parts by weight) using a ball mill for about 3 hours to mix and disperse the mixture. The urethane foam is immersed in the mixture, pulled up and centrifuged to remove most of the free binder. Dry at 150C for 15 minutes.
This was calcined in air at about 800 ° C., further reduced and heated at 1100 to 1200 ° C. in a hydrogen stream, and sintered to obtain a porous iron body.

After that, on the surface of the base to be attached with the porous metal body, nickel plating was previously applied to a thickness of about 1 μm under the same conditions as in the case of the base body. The substrate was cut into almost the same dimensions as the core body, heated to 800 ± 50 ° C. in a state where the core body was in contact with the core body, and then pressed and adhered. FIG. 1 is a cross-sectional view of a laminated state of the base metal body and the porous metal body before pressure bonding, and FIG. 2 is a cross-sectional view after pressure bonding. The current collector thus obtained was
It was bent at 180 degrees with respect to three kinds of diameters of 2, 4 mm, and the peel strength of the porous metal body from the core was visually evaluated based on the following criteria to evaluate the adhesion. The evaluation results are shown in Tables 1 and 2.

[Adhesion Evaluation Criteria] A: Cracks are formed in the porous metal body, but no peeling is observed. ：: Cracks are generated in the porous metal body, and slight peeling is observed at the center of the bending. C: Cracks are formed in the porous metal body, and cracks are observed in a considerable portion of the bent portion. ×: Peeling occurs at the entire bent portion, and the porous metal body falls off the core body. The average pore size was measured by cutting a sample and observing with a microscope.

[Examples 3 and 4] The thickness of the substrate core was 60 μm.
The conditions other than using the punched steel sheet of Examples 1-2
Is the same as

[Examples 5 to 8] Nickel powders having different average particle diameters were dispersed by using the same acrylic resin solution ball mill as in Examples 1 to 4, urethane foam was immersed in the powder, pulled up and centrifuged. Separate and remove most of the free binder, then dry at 150-200 ° C. for 15 minutes. This was calcined in air at about 800 ° C., further reduced and heated at 1100 to 1200 ° C. in a hydrogen stream, and sintered to obtain a porous iron body. In the same manner as in Examples 1 and 3, this nickel porous body was pressure-bonded to a base body made of an ordinary steel plate having a thickness of 80 μm or a punched steel plate having a thickness of 60 μm to obtain a battery current collector. Examples 5 and 6 are cases where a normal steel plate having a thickness of 80 μm is used for the base body, and Examples 7 and 8 are cases where a punched steel plate having a thickness of 60 μm is used.

[Examples 9 to 12] Stainless steel (SUS304) powders having different average particle diameters were dispersed in an acrylic resin solution, and urethane foam was immersed in the powder. I got a body. Examples 9 and 10 are cases where a normal steel plate having a thickness of 80 μm is used for the base body, and Examples 11 and 12 are cases where a punched steel plate having a thickness of 60 μm is used.

Example 13 A urethane foam having a diameter of 8
Using a porous metal body wound with an iron wire having a length of 0 μm and a length of 100 mm, immersing it in an α-iron oxide slurry in the same manner as in Example 1, heating and heating in a reducing atmosphere to obtain a porous metal body Is the case.

Example 14 A urethane foam having a diameter of 8
A wire wound with a nickel wire having a length of 0 μm and a length of 100 mm was used as a porous metal body, immersed in a nickel powder slurry in the same manner as in Example 9, and then fired and heated in a reducing atmosphere to obtain a porous metal body. Is the case.

Examples 15 and 16 A polyacrylonitrile-based carbon fiber sheet (PAN network) having a diameter of 80 μm and a length of 30
A sheet obtained by entangling stainless steel fibers of about 50 mm is prepared.
The mixture is fired for a minute, and further heated under a hydrogen gas atmosphere for about 1 hour to reduce the oxidized metal. Thereafter, the sintered sheet was subjected to nickel plating under the following conditions so as to have a thickness of 1 to 6 μm, thereby producing a porous metal body.

[Nickel plating bath composition and plating conditions] Nickel sulfate 300 g / L Nickel chloride 45 g / L Boric acid 30 g / L Bath temperature 50 ° C. pH 4.0-4.5 Current density 20 A / dm ²

[Comparative Examples 1 to 4] Comparative Examples 1 and 2 do not use the substrate cores produced as in Examples 1 and 2 of the present invention, but use This is the case. Comparative Examples 3 and 4 have the same structure as that of the present invention, except that the average pore diameter of the porous metal body after press-contact is out of the range of the present invention.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

According to the present invention, a porous metal body having an average pore diameter of 50 to 200 μm after being press-contacted to a nickel-phosphorus-plated substrate core is pressure-contacted to form a substrate core and a porous body. A strong battery current collector that does not easily peel off can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a laminated state before a base and a porous metal body are brought into close contact with each other under pressure.

FIG. 2 is a cross-sectional view of a battery current collector obtained by bringing a base and a porous metal body into close contact with each other under pressure.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideo Omura 1302 Higashitoyoi, Kudamatsu City, Yamaguchi Prefecture Toyo Kohan Co., Ltd. (72) Inventor Satoru Satoru Matsuo 1296-1, Higashitoyoi, Kudamatsu City, Yamaguchi Prefecture In-house Research Institute (72) Inventor Keiji Yamane 1-4-3 Kasumigaseki, Chiyoda-ku, Tokyo Toyo Kohan Co., Ltd. F-term (reference) 5H017 AA02 BB06 BB16 CC03 CC05 CC28 DD05 EE04 EE06 HH03 5H028 AA05 BB04 BB10 CC05 EE01 HH05

Claims (16)

[Claims] 1. A current collector for a secondary battery, wherein a porous metal body is laminated on and adhered to a metal substrate having a nickel-phosphorus alloy layer formed on a surface thereof. 2. The current collector for a secondary battery according to claim 1, wherein said alloy layer is formed by plating. 3. The current collector for a secondary battery according to claim 1, wherein the porous metal body is made of a metal containing iron, nickel, or an alloy thereof as a main component. 4. The method according to claim 1, wherein the average pore diameter after compression contact with the substrate is 5%.
2. A porous metal body having a thickness of 0 to 200 [mu] m.
Or the current collector for a secondary battery according to 2. 5. A method for manufacturing a current collector for a secondary battery, wherein a porous metal body is laminated and adhered on a metal substrate having a nickel-phosphorus alloy layer formed on a surface thereof. 6. The method according to claim 5, wherein the alloy layer is formed by a plating method. 7. The method for producing a current collector for a secondary battery according to claim 5, wherein the polynomial metal body is made of a metal containing iron, nickel or an alloy thereof as a main component. 8. An average pore diameter after compression contact with a substrate is 5
A porous metal body having a thickness of 0 to 200 µm is used.
Or a method for producing a current collector for a secondary battery according to item 6. 9. A secondary battery using, as a current collector, a substrate obtained by laminating and adhering a porous metal body on a metal substrate having a nickel-phosphorus alloy layer formed on its surface. 10. The secondary battery according to claim 9, wherein a substrate on which the alloy layer is formed by a plating method is used as a current collector. 11. The secondary battery according to claim 9, wherein the porous metal body is made of a metal having iron, nickel, or an alloy thereof as a main component. 12. The secondary battery used as a current collector according to claim 9, wherein a porous metal body having an average pore diameter of 50 to 200 μm after being pressed and adhered to the substrate is used. 13. A method for manufacturing a secondary battery, comprising using a substrate obtained by laminating and adhering a porous metal body on a metal substrate having a nickel-phosphorus alloy layer formed on a surface thereof as a current collector. 14. The method according to claim 13, wherein a substrate on which the alloy layer is formed by a plating method is used as a current collector. 15. The method for manufacturing a secondary battery according to claim 13, wherein the porous metal body is made of a metal containing iron, nickel or an alloy thereof as a main component. 16. An average pore diameter after compression contact with a substrate is 50.
14. Use of a porous metal body having a thickness of from 200 to 200 [mu] m.
15. A method for manufacturing a secondary battery according to 14 above.