JP2000348716A - Alloy powder sheet, its manufacture and its manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the electric resistance of a negative electrode material to enhance battery performance and enhance productivity by providing metal deposition films for the surfaces of alloy powder and by mutually bonding adjacent deposition films. SOLUTION: Hydrogen storage alloy powder 3 constituting an alloy powder sheet 5 has metal deposition films 6 on the surfaces thereof, and the adjacent metal deposition films 6 of the hydrogen storage alloy powder 3 are mutually bonded. Thereby, the hydrogen storage alloy powder 3 is partially wrapped in a mesh form by the metal deposition films 6, and the hydrogen storage alloy powder 3 is hardly changed into fine powder or collapsed even if heavy-current charge-discharge is repeated, so that the service life of a battery can be extended. Since the metal deposition films 6 have conductivity, the adjacent metal deposition films 6 can be mutually bonded by current-carrying rolling without using a binder, and as a result, the electric resistance of a negative electrode material is reduced, so that the heat generation of the battery is reduced and battery performance can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy powder sheet made of a powder of a hydrogen storage alloy and a method and an apparatus for producing the same.

[0002]

2. Description of the Related Art FIG. 4A is a structural view of a nickel-metal hydride secondary battery which is a kind of a secondary battery. As shown in this figure, for example, a nickel hydride secondary battery has a core called a core material. A negative electrode plate 1 made of a metal material and a hydrogen storage alloy is used.

FIG. 4B is a schematic sectional view of the negative electrode plate. As shown in this figure, an alloy powder sheet conventionally manufactured as a negative electrode material 1 of a nickel-metal hydride secondary battery has a punch sheet as a core material 2 in the center, and a hydrogen storage alloy 3 and an organic binder 4 on both surfaces thereof. Is applied by the adhesive force of a binder and dried, and then, as schematically shown in FIG. 4C, the thickness is adjusted by a press or the like to produce the mixture.

[0004]

However, the above-mentioned conventional means for producing an alloy powder sheet has the following problems. 1. Since the organic binder 4 is used as a fixing agent for the negative electrode material 1, the electric resistance when extracting electric charge from a battery using the negative electrode material 1 (for example, a nickel-metal hydride secondary battery) due to the insulating property of the organic binder itself is reduced. There is a limitation that charging and discharging of a large current cannot be performed. 2. Since the thickness accuracy is obtained by the pressing device, the operation is intermittent and the productivity is low.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide an alloy powder sheet that can reduce the electric resistance of a negative electrode material and improve battery performance and has high productivity, and a method and an apparatus for manufacturing the same.

[0006]

According to the present invention, there is provided an alloy powder sheet comprising a hydrogen storage alloy powder (3), which has a metal deposition film (6) on the surface of the alloy powder, An alloy powder sheet is provided, wherein the deposited films are bonded to each other.

Further, according to the present invention, a metal is deposited on the surface of the hydrogen storage alloy powder (3) to form a metal deposition film (6), and the alloy powder is electro-rolled to produce an alloy powder sheet. A method for producing an alloy powder sheet is provided.

According to the alloy powder sheet and the method of manufacturing the same according to the present invention, the metal is deposited on the surface of the hydrogen storage alloy powder (3) to form the metal deposited film (6). Bonding can be performed between the deposited metal films, and the hydrogen storage alloy becomes partially wrapped by the metal deposited film.This metal deposited film is electrically conductive, reducing the electrical resistance of the negative electrode material without an organic binder. Battery performance.

According to a preferred embodiment of the present invention, the alloy powder sheet further comprises a porous conductive metal foil (8).
And a metal deposition film (6) on the surface of the alloy powder is joined to the surface of the metal foil. By using such a metal foil as a core material, the tensile strength of the alloy powder sheet can be increased, and its productivity and workability as a battery component can be increased.

Further, according to the present invention, there is provided an energizing rolling device (12) for rolling while energizing between powders, and a reduction furnace (14a) provided downstream of the device, and comprising a porous conductive metal. The foil (8) is supplied as a core material between the current-carrying rolls (12a) of the current-rolling apparatus, and at the same time, the hydrogen-absorbing alloy fine powder (3) having the metal-deposited film (6) on the surface thereof is supplied. And the conductive metal foil (8) are mutually bonded,
Further, an apparatus for manufacturing an alloy powder sheet is provided, wherein the apparatus is further heated in a reducing atmosphere in a reducing furnace to further diffuse-bond the bonded portion.

[0011] With this configuration, the core material can be fed into a forming and rolling mill, and a hydrogen storage alloy can be fed along both sides thereof to be formed and wound into a roll shape. In comparison, it can be manufactured continuously, productivity can be increased, and thickness accuracy and shape quality can be made uniform by current rolling.

According to a preferred embodiment of the present invention, a powder roll forming apparatus (1) for forming a metal powder to form a porous metal foil is provided on the upstream side of the current rolling apparatus (12).
6) and a reduction furnace (14b) provided downstream of the apparatus.
The conductive metal foil (8) is formed from the conductive metal powder, and further heated in a reducing furnace in a reducing furnace, and supplied to the current rolling device (12).

With this configuration, the metal powder (for example, Ni powder)
A powder roll forming device for forming powder and a reduction furnace are continuously provided to form a core material from metal powder, and the core material is fed into a forming and rolling mill, and a hydrogen storage alloy and metal fine powder are placed on both sides thereof. The mixed material can be put along and formed. Therefore, the core material itself can be manufactured continuously, and the steps of winding, transporting and rewinding the core material can be omitted, productivity is further improved, and the thickness accuracy and shape quality of the core material are reduced by powder roll rolling. Can be made uniform.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, the same reference numerals are given to the common parts in the respective drawings, and the duplicate description will be omitted. FIG. 1 is a schematic view of an alloy powder sheet according to the present invention. In this figure, (A) is a hydrogen storage alloy powder,
(B) shows the first embodiment of the alloy powder sheet, and (C) shows the second embodiment of the alloy powder sheet.

As shown in FIG. 1A, the hydrogen storage alloy powder 3 constituting the alloy powder sheet 5 of the present invention has a metal deposition film 6 on its surface. 1 (B).
In the embodiment, the adjacent metal deposition films 6 of the hydrogen storage alloy powder 3 are joined to each other. Further, in the second embodiment shown in FIG. 1C, a conductive metal foil 8 is provided, and a metal vapor-deposited film 6 of an alloy powder in contact with the surface of the metal foil 8 is joined thereto.

The hydrogen storage alloy powder 3 is preferably made of AB
5 (LaNi5) powder, but a cheaper hydrogen storage alloy with a larger charge capacity, such as AB2 (TiMn1.5,
It may be a metal such as ZrMn2) or VTi. Also,
The particle size of the powder can be set variously depending on the use of the battery or the like to be used.

The metal deposition film 6 is preferably a nickel (Ni) film having a small electric resistance, but other metals may be used as long as the electric conductivity and air permeability are not impaired. The metal foil 8 is preferably a foil material formed by rolling Ni powder, but may be a punching plate made of a foil material having no air permeability. In addition, the thickness of the foil material can be arbitrarily set in view of manufacturing and battery assembly and its performance. Accordingly, a foil material having a thickness of 10 μm or less may be used, or a sheet material having a thickness greater than 10 μm may be used.

FIG. 2 is a schematic view of the method for producing an alloy powder sheet according to the present invention. In this figure, (A) shows a vacuum evaporation apparatus and (B) shows a current rolling apparatus. In the method of the present invention, a metal is deposited to cover the surface of the hydrogen-absorbing alloy powder 3 by using, for example, a vacuum deposition device 10 to form a metal deposition film 6. The powder is electro-rolled to produce an alloy powder sheet 5.

In FIG. 2A, 10a is a vacuum vessel,
Reference numeral 10b denotes an evaporated metal crucible, 10c denotes a hydrogen storage alloy tray, 11a denotes an electron gun, and 11b denotes an electromagnet. Using this vacuum deposition apparatus 10, a vacuum (for example, 10-4 to 10-6)
When the metal crucible 10b is heated by the electron gun 11a at (torr), metal vapor is generated. Since the metal vapor rises, the hydrogen storage metal powder 3 is placed on top of the metal vapor, and preferably, the metal vapor is applied to each powder while stirring. As a result, the metal vapor adheres to and adheres to the low-temperature hydrogen storage alloy powder 3 to cover the powder surface in a stitch shape, thereby forming the metal deposition film 6.

In FIG. 2 (B), reference numeral 12a denotes an energizing roll, 13a denotes a power source, and 13b denotes a current terminal. The energizing roll 12a energizes the metal powder 3 having the metal deposition film 6 while compressing it. The alloy powder sheet 5 can be manufactured by joining the metal deposition films 6.

According to the above-described alloy powder sheet and the method of manufacturing the same according to the present invention, the metal is deposited to cover the surface of the hydrogen storage alloy powder 3 to form the metal deposition film 6. Is partially wrapped in a stitch shape by the metal vapor-deposited film 6, making it difficult for the hydrogen storage alloy 3 to be pulverized and disintegrated even after repeated charging and discharging of a large current, thereby extending the life of the battery. . Further, since the metal-deposited film 6 is electrically conductive, the adjacent metal-deposited films 6 can be joined to each other without a binder by current rolling, whereby
By reducing the electric resistance of the negative electrode material, heat generation of the battery can be reduced and battery performance can be improved. Further, a hydrogen storage alloy having a low charge and a large charge capacity, for example, AB, can be used instead of expensive AB5 (LaNi5) because it can prevent pulverization and collapse.
2 (TiMn1.5, ZrMn2), VTi and other metals can be used. Furthermore, by providing a porous conductive metal foil 8 and bonding a metal vapor-deposited film 6 on the surface of the alloy powder to the surface thereof and using it as a core material, the tensile strength of the alloy powder sheet 5 is increased, thereby improving the productivity and the battery configuration. Workability as a part can be improved.

FIG. 3 is a block diagram of an apparatus for manufacturing an alloy powder sheet according to the present invention. In this figure, (A) shows the first
Embodiment, (B) shows a second embodiment. FIG.
As shown in (A), this manufacturing apparatus includes an energizing rolling apparatus 12 for energizing and rolling between powders, and a reduction furnace 14a provided downstream of the apparatus. The energizing rolling device 12
Hydrogen storage alloy powder 3 having a metal deposition film 6 on both sides of a core material (conductive metal foil 8) in addition to the above-described energizing roll 12a
Is provided. The reduction furnace 14a is preferably a hydrogen reduction furnace, and is configured to heat and hold the alloy powder sheet 5 continuously in a reducing atmosphere for a certain period of time. Further, in this example, the reduction furnace 14a
, A pinch roller 17a, a roller guide 17b,
A winding machine 15a is provided, and the core material 8 and the formed alloy powder sheet 5 fed back from the unwinding machine 15b on the upstream side are wound into a roll.

With this structure, the porous conductive metal foil 8 is supplied as a core material between the current-carrying rolls 12a of the current-rolling apparatus 12, and at the same time, the hydrogen-absorbing alloy fine powder 3 having the metal-deposited film 6 on the surface on both sides thereof is supplied. Then, the metal-deposited films and the conductive metal foil 8 are bonded to each other, and further heated in a reducing atmosphere in a reducing furnace 14a to further diffuse-bond the bonded portions. Therefore, as compared with the conventional intermittent operation of a press, continuous production can be performed, productivity can be improved, and plate thickness accuracy and shape quality can be made uniform by electric current rolling.

The manufacturing apparatus shown in FIG. 3B further includes a powder roll forming apparatus 16 for forming a metal powder to form a porous metal foil on the upstream side of the current rolling apparatus 12 and a downstream side of the apparatus. And a provided reduction furnace 14b. The powder roll forming device 16 has a powder roll 16a, between which the powder is formed into a sheet. Reduction furnace 14b
Is preferably a hydrogen reduction furnace, like the above-described reduction furnace 14a, in which the conductive metal foil 8 is continuously heated and held in a reducing atmosphere for a certain period of time. Further, in this example, a pinch roller 17c is provided on the downstream side of the reduction furnace 14b, and the conductive metal foil 8 manufactured from the powder is supplied directly to the current rolling mill 12. The winding machine 15
c may be separately provided, and the conductive metal foil 8 manufactured from the powder may be once wound into a roll, moved to the unwinding machine 15b, and unwound.

With the above-described configuration, the conductive metal foil 8 can be formed from the conductive metal powder, and further heated in a reducing atmosphere in the reduction furnace 14 b and supplied to the current rolling device 12. Therefore, the core material itself can be manufactured continuously, and the steps of winding, transporting and rewinding the core material can be omitted, productivity is further improved, and the thickness accuracy and shape quality of the core material are reduced by powder roll rolling. Can be made uniform.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention. For example, in the above description, the alloy powder sheet used as the negative electrode plate of the nickel-metal hydride battery has been described in detail, but the present invention is not limited to this, and can be similarly applied to alloy powder sheets for other uses.

[0027]

As described above, the alloy powder sheet and the method and apparatus for manufacturing the same according to the present invention can reduce the electric resistance of the negative electrode material to improve the battery performance and improve the productivity. Has excellent effects.

[Brief description of the drawings]

FIG. 1 is a schematic view of an alloy powder sheet according to the present invention.

FIG. 2 is a schematic view of the method for producing an alloy powder sheet of the present invention.

FIG. 3 is a configuration diagram of an apparatus for manufacturing an alloy powder sheet according to the present invention.

FIG. 4 is a schematic view of a conventional alloy powder sheet and a manufacturing method thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Negative electrode material 2 Core material 3 Hydrogen storage alloy 4 Organic binder 5 Alloy powder sheet 6 Metal deposition film 8 Conductive metal foil 10 Vacuum deposition device 10a Vacuum container 10b Metal deposition crucible 10c Hydrogen storage alloy tray 11a Electron gun 11b Electromagnet 12 Electricity Rolling device 12a Power supply roll 13a Power supply 13b Current terminal 14a, 14b Reduction furnace 15a, 15c Winding machine 15b Unwinder 16 Powder roll forming device 16a Powder forming roll 17a, 17c Pinch roller 17b Roller guide

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01M 4/62 H01M 4/64 A4 / 64 B22F 5/00 J F term (reference) 4K018 AA11 BA05 BC22 BD07 EA06 EA21 HA08 KA38 5H003 AA01 AA08 BB02 BC01 BC05 5H016 AA02 AA05 BB01 BB05 BB08 BB11 BB18 BB19 CC03 EE01 5H017 AA02 AS01 BB19 CC01 CC25 EE01

Claims (5)

[Claims] 1. An alloy powder sheet comprising a hydrogen storage alloy powder (3), comprising a metal vapor-deposited film (6) on the surface of the alloy powder, wherein adjacent metal vapor-deposited films are joined to each other. An alloy powder sheet, characterized in that: 2. A metal film (6) comprising a porous conductive metal foil (8), and a metal vapor-deposited film (6) on the surface of the alloy powder on the surface of the metal foil.
The alloy powder sheet according to claim 1, wherein the alloy powder sheet is bonded. 3. An alloy characterized in that a metal is deposited on the surface of the hydrogen storage alloy powder (3) to form a metal deposition film (6), and the alloy powder is electro-rolled to produce an alloy powder sheet. Manufacturing method of powder sheet. 4. An electro-rolling apparatus (12) for rolling while energizing between powders, and a reduction furnace (14a) provided downstream of the apparatus, wherein a porous conductive metal foil (8) is used as a core. As a material, a hydrogen storage alloy fine powder (3) having a metal vapor-deposited film (6) on its surface is supplied at the same time between the current-carrying rolls (12a) of the current-rolling apparatus, and between the metal vapor-deposited films and the conductive metal foil ( 8) The apparatus for manufacturing an alloy powder sheet, wherein the parts are bonded to each other, and further heated in a reducing atmosphere in a reducing furnace to further diffuse-bond the bonded parts. 5. An upstream side of said current rolling mill (12),
A powder roll forming apparatus (16) for forming a metal powder to form a porous metal foil; and a reduction furnace (14b) provided downstream of the apparatus, wherein a conductive metal foil is formed from the conductive metal foil ( 8. The alloy powder sheet manufacturing apparatus according to claim 4, wherein 8) is formed, further heated in a reducing atmosphere in a reducing furnace, and supplied to the current rolling device (12).