WO1999054945A1

WO1999054945A1 - Secondary battery electrode substrate core, secondary battery electrode substrate, methods of manufacturing them and electrode and battery using them

Info

Publication number: WO1999054945A1
Application number: PCT/JP1999/002092
Authority: WO
Inventors: Hitoshi Ohmura; Tatsuo Tomomori; Hideo Ohmura
Original assignee: Toyo Kohan Co., Ltd.
Priority date: 1998-04-20
Filing date: 1999-04-20
Publication date: 1999-10-28
Also published as: AU3172399A

Abstract

A secondary battery electrode substrate obtained by sintering a porous layer onto a metal core assembled by being wound on a cylindrical battery, specifically, a secondary battery electrode substrate having a porous metal layer sintered material capable of being sintered at a comparatively low temperature, free from separation or coming-off from the metal core and excellent in adhesiveness, wherein a nickel layer is formed on at least one surface of a steel sheet, a low-melting-point metal layer is formed thereon, nickel powder is laminated thereon and the nickel powder is sintered at the melting point of the low-melting-point metal or higher and at temperatures lower than the melting point of nickel to form the porous sintered material which is then joined to the steel sheet.

Description

Description Core for secondary battery electrode base, secondary battery electrode base, method for producing them, electrode and battery using them

s

Technical field

The present invention relates to a core material for a secondary battery electrode substrate used for a secondary battery such as a nickel-cadmium battery and a nickel-hydrogen battery, a core material for a secondary battery electrode substrate, and a secondary material using the same. Battery electrode base, and secondary battery electrode and secondary battery using the same

(Regarding C batteries.

In order to enable a large current to be taken out, nickel-based single-layer batteries used for high-power applications use electrodes consisting of a base made of a porous metal sintered body with a large surface area. I have. This sintered substrate is formed by pressing nickel powder or by applying a slurry-like nickel powder on a core body, which is a perforated steel sheet (punched steel sheet) with a thickness of 60 to 80 zm plated with nickel. It is manufactured by applying it by applying it, and sintering it in a non-oxidizing atmosphere at a temperature of 900 to 110 ° C. In the above temperature range, necking occurs in the contact portion between the nickel powders due to solid-phase diffusion, so-called solid-phase sintering occurs, and at the same time, nickel contacts the nickel-punched steel sheet and the nickel powder in the contact portion. Bonding by solid phase diffusion occurs. In this way, the nickel powder is bonded to each other at the necking portion, and a nickel porous sintered body having a porosity of 80% or more, on which a network is formed, is bonded to a steel sheet to produce an electrode substrate for a secondary battery. Have been.

In the electrode base for a secondary battery having a structure in which a porous metal sintered body and a metal core are joined only by such solid phase diffusion, the base is cylindrical because the adhesion is insufficient. When a porous metal sintered body is wound into a battery case of a rechargeable battery and incorporated, it often peels off or falls off from the metal core. This phenomenon occurs remarkably at the center of the winding with a small winding radius. As shown in Fig. 1 (a), the porous metal sintered body peels off from the metal core, causing the active material to fall off or fall off. A problem arises when the active material of the porous metal sintered body breaks through the separator and short-circuits.

For the purpose of improving the adhesion between the porous metal sintered body and the metal core constituting the electrode substrate for a secondary battery, and improving the strength of the porous metal sintered body, the inventors of the present invention have already (International Publication W0997 / 16312). That is, a nickel layer is formed on at least one side of the steel sheet, and nickel

[Nickel powder is laminated on a core on which a nickel-phosphorous layer having a lower melting point than the nickel layer is formed, and the mixed powder is sintered at a temperature equal to or higher than the melting point of the nickel-phosphorous layer and lower than the melting point of the nickel powder. A porous layer is formed as a substrate, or a nickel layer is formed on at least one side of a steel sheet, and a nickel layer is formed on the core body. The powder is laminated, and the mixed powder is sintered at a temperature equal to or higher than the melting point of the borated layer and lower than the melting point of the nickel powder to form a porous layer to form a base.

In these attempts, a small amount of liquid phase is generated in the step of sintering the nickel powder and the nickel powder and the core to form a porous metal layer, and the nickel powder and the nickel powder and the core are sintered. To promote the interdiffusion of nickel and obtain a substrate with excellent adhesion, but the melting points of the nickel-phosphorus layer and the nickel boride layer are lower than the melting points of nickel powder and steel sheet, but the adhesion is excellent. In order to generate a liquid phase in order to obtain a substrate, it is necessary to perform sintering at a considerably high temperature of about 900 to 115 ° C. If sintering is performed at such a high temperature, the liquid phase that appears may reduce the porosity of the sintered porous metal or cause distortion in the steel plate as the core substrate, It requires heating energy and is not economically favorable.

In the present invention, a porous material is formed on a metal The electrode substrate for secondary batteries obtained by sintering the porous metal layer can be sintered at a relatively low temperature and has excellent adhesion without peeling off or falling off from the metal core. It is an object to provide an electrode substrate for a secondary battery having a binder. Disclosure of the invention

In the core for a secondary battery electrode substrate of the present invention, a nickel layer is formed on at least one surface of a steel sheet, and a low-melting metal layer is further formed thereon, and the low-melting metal is tin or zinc. Further, the core has a large number of small-diameter holes.

(D The method for producing a core for a secondary battery electrode substrate of the present invention comprises forming a nickel layer on at least one surface of a steel sheet, and further forming a low-melting metal layer on the nickel layer. Is tin or indium, and the core has many small-diameter holes.

The secondary battery electrode substrate of the present invention is characterized in that a porous layer is formed on at least one surface of a steel plate, on an upper layer of a core having nickel and a low melting point gold (metal alloy layer formed thereon), and The metal is tin or indium, and the porous layer is obtained by sintering Nigel powder.

In the method for producing a secondary battery electrode substrate of the present invention, a nickel powder is laminated on the upper layer of the core, and heated to a temperature equal to or higher than the melting point of the low melting point metal and lower than the melting point of nickel. Forming a porous layer by sintering the nickel powder and simultaneously bonding the core and the porous layer. Is tin or zinc. The secondary battery electrode of the present invention is characterized in that the above-mentioned secondary battery electrode substrate is impregnated with an active material, and the secondary battery of the present invention is characterized by using the above-mentioned secondary battery electrode. And BRIEF DESCRIPTION OF THE FIGURES

1A is a conceptual diagram of a conventional electrode substrate for a secondary battery, and FIG. 1B is a conceptual diagram of an electrode substrate for a secondary battery of the present invention. FIG. 2 is a graph showing charge / discharge characteristics.

& BEST MODE FOR CARRYING OUT THE INVENTION

The electrode substrate of the present invention comprises a core formed by forming a nickel plating layer and a plating layer of a low melting point metal such as tin or indium on at least one surface of a steel sheet, and further laminating nickel powder on an upper layer of the core. Heating at a temperature above the melting point and below the melting point of Nigel to form an alloy layer consisting of nickel and low melting point metal on the steel sheet,

(0 A porous layer formed by sintering nickel powder is provided, and at the same time, the porous layer is bonded to the core. By bonding the core and the porous layer in this manner, the battery is wound around a cylindrical battery. A secondary electrode substrate with excellent adhesion can be obtained, in which the porous layer does not peel off or fall off from the metal core when incorporated.

It is essential that the electrode substrate for a secondary battery of the present invention has a surface area as large as possible in order to be able to extract a large current. For this purpose, a porous layer is provided on a metal plate serving as a core to form an electrode substrate. The core substrate may be a steel plate or a steel plate in which a large number of small holes of about 1 to 3 mm are formed by, for example, punching, a chemical etching method, an electrochemical etching method, a sand blast, an emboss roll, or the like. A steel sheet whose surface has been roughened using mechanical means such as rolling

Then, a nickel plating is applied thereon, and a lower melting point metal such as tin or indium is applied thereon. Further, a stainless steel plate or a nickel plate may be used instead of the steel plate.

The electrode substrate of the present invention is characterized in that nickel powder is laminated on the plating layer of the core, and heated to a temperature higher than the melting point of the low-melting metal and lower than the melting point of Nickel.

^ The plating layer of the melting point metal is melted to form a liquid phase, and a steel core is formed with an alloy layer composed of nickel and a low melting point metal, and Nigel powder is formed on the core. The porous layer is formed by sintering, and at the same time, the diffusion of the nickel porous layer and the alloy layer composed of nickel and a low melting point metal is promoted, and a strong bond is obtained.

As the nickel plating for forming a nickel layer on the steel sheet, electric plating is preferable from the viewpoint of productivity, and gloss plating, matte plating, and semi-gloss using a known Watt bath or sulfamic acid bath are used. A plating or the like can be used. It is also possible to use nickel-phosphorus alloy plating instead of nickel plating. In this case, the plating bath was composed mainly of nickel sulfate and nickel chloride, and phosphorous acid, hypophosphorous acid, and / or phosphite, hypophosphite, etc. were added as a source of phosphorus. It is preferred to use a bath. The above plating thickness is preferably in the range of 0.5 to 10 μm.

As the plating of the low melting point metal applied on the nickel plating layer, similarly to the nickel plating, electric plating is preferable from the viewpoint of productivity. In the case of applying tin plating as the low-melting metal plating, any of known plating baths such as an acidic bath, an alkali bath and a plating bath may be used. In the present invention, a stannous sulfate bath or a phenol sulfone bath is used. H

An ionic acid bath is preferably used. As a plating bath for applying indium plating, a sulfuric acid bath, a sulfamic acid bath and a borofluoride bath are suitably used. The plating thickness is preferably in the range of 0.2 to 5 m. If it is less than 0.2 // m, a sufficient liquid phase will not be generated, and strong bonding cannot be obtained. On the other hand, if it exceeds 5 zm, an excessive liquid phase is generated and penetrates into the pores of the sintered body, so that the porosity is reduced, and it is not economically preferable.

A nickel plating layer and a low-melting-point metal plating layer are formed on a steel sheet as described above to form a core, on which metal powder constituting a porous layer is laminated and sintered, and a secondary battery electrode base is formed. And Since the secondary battery electrode base is filled with an active material and then comes into contact with a strongly alkaline electrolyte, excellent alkali resistance is required. From such a viewpoint, the metal powder is preferably nickel powder or an alloy powder containing nickel as a main component.

The particle size of the nickel powder is appropriately selected in consideration of the porosity and strength of the sintered body. Many In order to increase the porosity, it is better to use coarse powder having a large particle size, but sufficient strength cannot be obtained because the number of contact points between powder particles per unit volume decreases. On the other hand, when fine powder having a small particle size is used, the strength of the sintered body increases, but sufficient porosity cannot be obtained. The preferred range of the particle size of the metal powder is 2 to 10 im.

The above nickel powder is dispersed in water or an organic solvent to form a slurry together with a viscous agent made of a water-soluble resin or a resin that dissolves in a specific organic solvent. Is applied on the formed tin layer. The addition amount of the dispersant, water or organic solvent to the metal powder is adjusted so that the viscosity of the slurry is uniformly applied to a predetermined thickness. After applying this slurry, water or organic solvent is dried and removed. After the nickel powder is adhered and fixed with the viscosifying agent as described above, the powder is heated in a reducing atmosphere to sinter the nickel powder to form a porous layer and join the porous layer to the core. Let it. As the reducing atmosphere, a vacuum or a mixed gas of hydrogen and nitrogen such as an ammonia decomposition gas can be used. It is essential that the sintering temperature be higher than the melting point of the low melting point metal and lower than the melting point of nickel, but without causing distortion in the core and sintering without consuming a large amount of heating energy. In order to complete the process, it is preferable that the temperature is as low as possible. On the other hand, since the base obtained by sintering the nickel powder on the core is in contact with the strong alkaline solution, it is not preferable that the low melting point metal dissolved in the alkaline solution remains in the base of the present invention, and the sintering is completed. Later, all low melting metals must be alloyed with nickel or steel sheet iron. In view of the above circumstances, the sintering temperature is 3 0 0~9 0 0 ^D range C is rather preferable, and more preferably in the range of 5 5 0~8 0 0 ° C.

As described above, a secondary battery electrode substrate in which a porous body formed by sintering nickel powder is joined to a core body obtained by forming an alloy layer made of nickel-low melting point metal on at least one surface of a steel sheet. Can be manufactured.

The secondary battery electrode substrate obtained as described above is impregnated with nickel nitrate as an active material, and alkali-treated in an aqueous sodium hydroxide solution to prepare a nickel hydroxide electrode. To form a secondary battery electrode.

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Examples 1-4, 6, 7)

A nickel steel plate having a thickness shown in Table 1 was applied to a steel plate having a thickness of 80 zm by using a Watt bath having the following composition and changing the electrolysis time with a current density l OAZdm ² .

[Pet bath]

Nickel sulfate 3 0 08 1

Nickel chloride 45 gZ l

Boric acid 30 g / l

(0 bath temperature 5 5 ° C

pH 4-4.5

Further, a tin plating having a thickness shown in Table 1 was applied to the upper layer by using a phenolsulfonic acid bath having the following composition and changing the electrolysis time at a current density of 10 A / dm ² .

[Phenolic sulfonic acid bath]

Stannous sulfate 30 g / l

Phenolsulfonic acid 60 g / l

Ethoxylated α-naphthol 5 g / l

Bath temperature 50 ° C

As described above, a nickel plating layer and a tin plating layer were formed on a steel sheet to obtain a 2D core. A large number of holes having a diameter of 1 mm were formed in a part of the core body thus obtained using a punching press (punched steel plate). Porous nickel sintered bodies were formed on both surfaces of these cores in the following manner. Carboxymethylcellulose was dissolved in water as a thickener to make a 4% aqueous solution. A nickel powder having a particle size of 2 to 3 was dispersed in the aqueous solution of the viscous slurry to form a slurry. This slurry was applied to both sides of the above-mentioned core using a coating machine to a uniform thickness, and then the water was evaporated and dried in an electric oven. The core body with the nickel powder adhered and fixed in this way is The electrode base having a porous nickel sintered body (porous layer) on a core was cooled by heating at a temperature shown in Table 1 for 15 minutes in a mixed gas consisting of 25% hydrogen and the balance nitrogen. Obtained. The obtained electrode substrate was bent at 180 degrees at three different diameters, lmm diameter, 2 mm diameter and 4 mm diameter, and the peeling degree of the nickel sintered core from the steel plate was as follows.

5 Visual evaluation was performed according to the criteria shown below, and the adhesion of the nickel sintered body to the steel sheet was evaluated. Table 2 shows the evaluation results.

[Evaluation criteria]

A: Cracks are formed in the nickel sintered body, but no peeling is observed.

〇: Cracks occur in the nickel sintered body, and slight peeling is observed at the center of bending.

Δ: Cracks are formed in the nickel sintered body, and peeling is observed in a considerable part of the bent portion.

X: Separation occurs in the entire bending, and the sintered body falls off.

(Example 5)

The steel of a large number of lmm thickness 60 // m, which holes were formed in the diameter (punching steel sheet), using a sulfamic acid bath having the following composition, a nickel plating thickness indicated at a current density of 10 AZdm ² in Table 1 gave.

[Sulfamic acid bath]

Nickel sulfamate 400 g / 1

D Nickel chloride 20 g / 1

Boric acid 30 g / 1

Sodium lauryl sulfate 0.5 g / 1

Bath temperature 5 OX

PH 4

ζΤ Further, a borofluoride bath having the following composition was applied to the upper layer, and indium plating was applied at a current density of 15 AZdm ² and the thickness shown in Table 1 to obtain a core. · [Borofluoride bath]

Indium borofluoride 250 g / 1

Boric acid 30 g Z 1

Ammonium borofluoride 50 g / 1

Bath temperature 3 O t:

H 1 ~ 1.5

Further, a slurry containing nickel powder was applied to both surfaces of the core in the same manner as in Example 1, dried and then heated at a temperature shown in Table 1 so as to form a porous nickel sintered body ( (Porous layer) was obtained. With respect to the obtained electrode substrate, the degree of peeling of the nickel sintered body from the steel sheet was visually evaluated in the same manner as in Example 1 \, and the adhesion of the nickel sintered body to the steel sheet was evaluated. Table 2 shows the evaluation results.

(Comparative Example 1, Comparative Example 2)

The same steel sheet as in Example 1 was coated with only a nickel plating layer in the same manner as in Example 1 to obtain a core having a nickel plating thickness shown in Table 1.

ί Further, a slurry containing nickel powder was applied to both surfaces of the core as shown in Table 1 and dried in the same manner as in Example 1, and then uniformly heated at the temperature shown in Table 1 to form a multi-layer on the core. An electrode substrate having a porous nickel sintered body (porous layer) was obtained. About the obtained electrode substrate, the peeling degree of the core of the nickel sintered body from the steel plate was visually evaluated in the same manner as in Example 1, and the adhesion of the nickel sintered body to the steel plate was evaluated. Table 2 shows the evaluation results.

Show 2D.

(Comparative Example 3, Comparative Example 4)

A punched steel sheet similar to that in Example 5 was subjected to nickel plating only to obtain a core having a nickel plating thickness shown in Table 1.

Further, a slurry containing nickel powder 5 ″ was applied to both surfaces of the core in the same manner as in Example 1 as shown in Table 1 and dried, and then uniformly heated at the temperature shown in Table 1 and placed on the core. An electrode substrate having a porous nickel sintered body (porous layer) was obtained. 54945

Ten

Then, in the same manner as in Example 1, the degree of peeling of the core of the nickel sintered body from the steel sheet was visually evaluated, and the adhesion of the nickel sintered body to the steel sheet was evaluated. Table 2 shows the evaluation results.

Table 1 Sample Description

Note) *: Punching after plating Table 2

Evaluation of Adhesion of Nickel Sintered Body to Core Sample Evaluation of Adhesion by Sample 180-degree Bend

1 mm bending 2 mm bending 4 mm bending

1 〇 ◎ ◎ Example 1

2 ◎ ◎ ◎ Example 2

3 ◎ ◎ ◎ Example 3

4 ◎ ◎ ◎ Example 4

5 〇 ◎ ◎ Example 5

6 X X Δ Comparative Example 1

7 X Δ 〇 Comparative Example 2

8 X Δ 比較 Comparative Example 3

9 Δ 〇比較 Comparative Example 4

1 0 ◎ ◎ ◎ Example 6

1 1 〇 ◎ ◎ Example 7 As shown in FIG. 1, the electrode substrate made using the core according to the present invention has an extremely excellent adhesive force between the sintered body (porous layer) and the core. Very little exfoliation and detachment of body (porous layer).

(Evaluation of electrode characteristics)

The electrode substrate of Example 3 was immersed in an aqueous solution of Nigel nitrate under reduced pressure to impregnate Nigel nitrate into a porous nickel sintered body (porous layer). The porous nickel sintered body was alkali-treated with a 25% by weight aqueous sodium hydroxide solution to obtain nickel hydroxide, which was used as a battery electrode. Similarly, an electrode of the electrode substrate of Comparative Example 1 was prepared.

(0 Using a nickel mesh as a counter electrode and a silver / silver chloride electrode as a reference electrode, the charge / discharge characteristics when this electrode is used as a positive electrode in a 6 N potassium hydroxide solution under a constant current (discharge rate: 3 C) Was measured.

FIG. 2 shows the results of measurement using the electrode of the present invention prepared from the electrode substrate of Example 3 and the conventional electrode prepared from the electrode substrate of Comparative Example 1. As shown in FIG. 2, a battery using an electrode manufactured from an electrode substrate manufactured using the core of the present invention has reduced polarization and exhibits excellent charge / discharge characteristics. The reason for this is that the secondary battery electrode substrate of the present invention has a porous layer having excellent adhesion. Industrial applicability

2.0 The core for a secondary battery electrode substrate of the present invention has a nickel layer on a steel plate and a layer of a low melting point metal such as tin or zinc formed thereon, and the core has a large number of small-diameter holes. May be. Further, a perforated steel plate (punched metal) obtained by performing a punching process on a steel plate may be subjected to the plating. In the secondary battery electrode base of the present invention, a porous layer obtained by sintering nickel powder is formed on the core, and the porous layer is formed even when severe processing such as bending is performed. It does not peel off from steel plates. In the production of the secondary battery electrode substrate of the present invention, the porous layer is obtained by sintering nickel powder, and the nickel powder is melted by sintering the plating layer of the low melting point metal. Diffusion of the alloy layer composed of nickel and low melting point metal between the core and the nickel sintered body and the core body is promoted, so the adhesion between the core body and the porous sintered body is excellent, and it is severe such as bending The porous layer does not peel off even after processing. In addition, alloys composed of Nigel and Nikkel-low melting point metals have excellent resistance to alkalinity and exhibit excellent corrosion resistance when exposed to alkaline electrolytes.

Further, the electrode of the present invention is obtained by impregnating any of the above electrode substrates with an active material to form an electrode, and a secondary battery using this electrode exhibits excellent charge / discharge characteristics.

Claims

The scope of the claims

I. A core for a secondary battery electrode substrate in which a nickel layer is formed on at least one surface of a steel sheet, and a low-melting metal layer is further formed thereon.

2. The core for a secondary battery electrode substrate according to claim 1, wherein the low melting point metal is tin or indium.

3. The core according to claim 1, wherein the core has a large number of small-diameter holes.

4. A method for producing a core for a secondary battery electrode substrate in which a nickel layer is formed on at least one side of a steel sheet, and a low-melting (zero-point metal layer) is formed thereon.

5. The method for producing a core for a secondary battery electrode base according to claim 4, wherein the low-melting-point metal is tin or zinc.

6. The method for manufacturing a core according to claim 4, wherein the core has a large number of small-diameter holes.

7. A secondary battery electrode substrate in which a porous layer is formed on a core having a nickel-low melting point metal alloy layer formed on at least one surface of a steel plate.

8. The secondary battery electrode base according to claim 7, wherein the porous layer is formed by sintering nickel powder.

9. The secondary battery electrode base according to claim 7, wherein the low melting point metal is tin or indium.

10. The secondary battery electrode base according to any one of claims 7 to 9, wherein the core body has a large number of small-diameter holes.

I I. A nickel powder is laminated on the upper layer of the core body according to any one of claims 1 to 3, and heated to a temperature higher than the melting point of the low melting point metal and lower than the melting point of nickel.

2ζ A secondary battery electrode for forming the nickel-low melting point metal alloy layer, sintering the nickel powder to form a porous layer, and joining the core and the porous layer. A method for manufacturing a substrate.

12. The method for manufacturing a secondary battery electrode substrate according to claim 11, wherein the low melting point metal is tin or zinc.

13. A secondary battery electrode according to any one of claims 7 to 10, wherein the secondary battery electrode base is impregnated with an active material.

14. A secondary battery using the secondary battery electrode according to claim 13.