JPH0917432A - Electrode substrate for battery and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide an electrode substrate to be used for alkaline secondary batteries such as Ni-Cd batteries, Ni-Zn batteries, Ni-H2 batteries. CONSTITUTION: An electrode substrate for batteries is made of a metal-based porous body having three-dimensional mesh structure and consisting of Cu or a Cu alloy as an inner part of a skeleton and Ni or a Ni alloy as a surface part and at the same time the substrate has a region in which both the inner part of the skeleton and the surface part are partly made of Ni or a Ni alloy at parts along dividing lines. The Cu or Cu alloy part in the inner part of the skeleton and the Ni or Ni alloy part are formed by a method involving a process to successively apply respective slurries to respectively proper regions of a porous resin core body and then a process to fire the resultant body or a method involving a process to apply binder resin to the surface of a porous resin core body, a process to coat respectively proper regions with Cu or a Cu alloy powder and with Ni or a Ni alloy powder, a process to fix the resin, a process to fire the resultant resin core body, and then a process to coat the surface part with Ni or a Ni alloy by electric deposition. Consequently, an electrode substrate for battery with low resistance and high corrosion resistance is materialized and in the case the electrode substrate is used for an alkaline secondary battery, high output is obtained and charging and discharging are carried out at high efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode substrate used in alkaline secondary batteries such as nickel-cadmium batteries, nickel-zinc batteries and nickel-hydrogen batteries.

[0002]

2. Description of the Related Art Lead-acid batteries and alkaline batteries are used as storage batteries used as various power sources. Among them, the alkaline storage battery has been widely used for various portable devices, and the large type for industrial purposes because it is expected to have high reliability and can be made compact and lightweight. In addition to cadmium, zinc, iron, hydrogen, etc. are targeted as the negative electrode in this alkaline storage battery. However, as the positive electrode, an air electrode, a silver oxide electrode, and the like are partially taken up, but in most cases, it is a nickel electrode. The characteristics have been improved from the pocket type to the sintering type, and the sealing has been made possible and the use has expanded.

However, in the ordinary powder sintering method, when the porosity of the substrate is 85% or more, the strength is significantly lowered, so that there is a limit to the filling of the active material, and therefore, there is a limit to increase the capacity of the battery. Therefore, as a substrate having a higher porosity of 90% or more, a foamed substrate or a fibrous substrate has been picked up and put into practical use instead of the sintered substrate. As a method for producing such a porous metal substrate having a high porosity, Japanese Patent Application Laid-Open No. S5-5200 is known.
There are a method by a plating method disclosed in JP-A-7-174484 and a method by a sintering method disclosed in JP-B-38-17554. In the plating method, carbon powder or the like is applied to the skeleton surface of a foamed resin such as urethane foam to perform a conductive treatment, and Ni is electrodeposited thereon by an electroplating method, after which the foamed resin and carbon are eliminated, The method is to obtain a metal porous body. On the other hand, in the sintering method, slurry metal powder is impregnated and applied on the skeleton surface of foamed resin such as urethane foam, and then heated to sinter the metal powder. As a porous metal body using these methods, "Celmet" made of Ni metal [trade name: manufactured by Sumitomo Electric Industries, Ltd.] is already on the market and used as an electrode plate for an alkaline secondary battery. .

[0004]

As described in the prior art, by applying the metal porous body as the battery electrode substrate, the contribution to the high capacity of the battery has been great. However, in a large alkaline secondary battery intended for an electric vehicle or the like, a battery electrode substrate using a conventional Ni porous body has a large electrode area, so that the electric resistance as the electrode substrate increases and There is a large voltage drop during rate discharge, there is a limit to the output that can be taken out as a battery, and a potential distribution occurs within the surface of the electrode substrate, and charging efficiency also drops. It is an object of the present invention to provide an electrode substrate having a low electric resistance, capable of high output, excellent in corrosion resistance, and particularly suitable for an alkaline secondary battery, and a method for producing the same, under these circumstances. .

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above problems can be achieved by an electrode substrate made of a specific metal porous body, and have completed the present invention. A first aspect of the present invention is a battery electrode substrate for forming an active material holder used as a current collector for a battery, which has a three-dimensional network structure in which the skeleton interior is Cu or Cu alloy and the surface portion is Ni or Ni alloy. An electrode substrate for a battery, which is composed of a porous metal body and partially has a region in which the skeleton is made of Ni or a Ni alloy both inside and outside thereof.

The specific resistance of Cu or Cu alloy, which is the inside of the skeleton, is about ¼ of that of Ni, so that the electric resistance of the porous metal body can be reduced, and when used as a battery electrode substrate. The above problems can be solved. Further, since Cu or Cu alloy easily elutes in the alkaline electrolyte in the battery, by coating the surface with Ni, Cu elution can be avoided, corrosion resistance as an electrode substrate can be improved, and life characteristics as a battery can be improved. Improve. However, in an actual battery manufacturing process, an electrode substrate is prepared by cutting a metal porous body into a predetermined size and then filling it with an active material or by filling the active material and then cutting it into a predetermined size. Is produced, but in either case, C is
An exposed portion of u or Cu alloy is produced. That is, FIG.
2 is an enlarged view of a part of the cross section of the porous network structure when the electrode substrate 1 shown in FIG.
As shown in (b), Cu (or Cu alloy) inside the skeleton covered with Ni plating is exposed.

According to the structure of the present invention, the portion along the dividing line C as shown in FIG. 1 (a) is a region where the skeleton is only Ni or Ni alloy as shown in FIG. 1 (b). Only Ni or a Ni alloy is exposed on the end surface of the electrode substrate 1 after cutting, so that corrosion resistance can be secured. Therefore, when applied to an alkaline secondary battery, high output and high efficiency charging / discharging becomes possible. A second aspect of the present invention is a method for manufacturing the above-mentioned battery electrode substrate. That is, the Cu or Cu alloy and the Ni or Ni alloy portion inside the skeleton of the metal porous body is divided into the slurry containing the Cu or Cu alloy powder and the slurry containing the Ni or Ni alloy powder on the porous resin core body for each region. By sequentially applying and then sintering, or after applying the binder resin to the surface of the porous resin core,
Cu or Cu alloy powder and N before the resin is dried and solidified
This is a method in which i or Ni alloy powder is directly applied to each region in order, the resin is fixed and then sintered, and the Ni or Ni alloy on the surface is formed by electroplating.

In the above-mentioned region where the Cu or Cu alloy layer is excluded, a portion other than the Cu or Cu alloy portion formation is masked by a metal mask or the like to form Cu or Cu.
The alloy powder is applied or applied, and then the Cu or Cu alloy forming portion is masked with a metal mask or the like to form Ni.
Alternatively, it is formed by applying or applying Ni alloy powder. By these methods, the inside of the skeleton is N
It is possible to obtain a porous metal body in which the laminated structure of i and the cut and processed portion are both made of Ni in the skeleton and in the surface portion. A polyurethane foam resin is typically used as the porous resin core. Alternatively, woven or non-woven fabric made of resin fibers may be used.

[0009]

【Example】

Example 1 Cu powder having an average particle size of 10 μm in weight% and an average particle size of 6
50% each for Ni powder of μm, acrylic resin 10
%, Carboxymethyl cellulose 2%, and water 38% were mixed and mixed for 5 hours to prepare Cu and Ni slurries. 2.5 mm thick with about 50 holes per inch
Each polyurethane foam was masked with a metal mask made of stainless steel having a thickness of 20 μm except for the Cu skeleton-forming portion, impregnated with Cu powder slurry, and excess impregnated coating was removed with a squeezing roll. Next, the Cu powder slurry coated portion was masked in the same manner to be impregnated with the Ni powder slurry, and the excess impregnated coating was removed with a squeezing roll. After being left to dry at room temperature for 1 hour, the coated product was heated to 1050 ° C. at a heating rate of 30 ° C./min in a hydrogen stream,
A heat treatment was performed at 0 ° C. for 10 minutes to obtain a Cu porous body having a three-dimensional network structure having a Ni portion locally. The average surface density of this porous metal body was 450 g / m ² . Then, the metal porous body was plated with Ni at 100 g / m ² at a current density of 10 A / dm ² in a Watt bath for electric Ni plating.
This is designated as Sample A.

Polyurethane foam having a thickness of 2.5 mm and about 50 pores per inch is made of acrylic resin 60.
After impregnating a binder resin liquid in which wt% and 40 wt% of water were mixed, the excess coating was removed with a squeeze roll to prepare a binder-coated porous resin core. Next, except for the Cu skeleton forming portion, the thickness of the porous resin core is 20 μm.
Masking with a stainless steel metal mask of m,
Cu powder having an average particle diameter of 10 μm was directly sprayed and applied by an air gun. Subsequently, the Cu powder coating portion was similarly masked, and Ni powder having an average particle diameter of 6 μm was directly sprayed and coated by an air gun. After being left to dry at room temperature for 1 hour, this coated material was heated in a hydrogen stream at a heating rate of 30 ° C./min to 1050 ° C. and heat-treated at 1050 ° C. for 10 minutes to locally A Cu porous body having a three-dimensional network structure having a Ni portion was obtained. The average surface density of this porous metal body was 450 g / m ² . Then, the metal porous body was plated with Ni at 100 g / m ² at a current density of 10 A / dm ² in a Watt bath for electric Ni plating. This is sample B
And

As a comparative example, Cu slurry of Sample A and urethane foam were used to impregnate Cu powder slurry, and the excess impregnated coating was removed with a squeezing roll, and the mixture was kept at room temperature for 1 hour.
After being left to dry for a period of time, the coated product was heated to 1050 ° C. at a heating rate of 30 ° C./min in a hydrogen stream and heated to 1050 ° C.
A Cu porous body having a three-dimensional network structure was obtained by performing heat treatment at 10 ° C. for 10 minutes. The average surface density of this porous metal body is 45.
It was 0 g / m ² . Then, the Ni metal
Ni plating was performed at 100 g / m ² at a current density of 10 A / dm ² in a plating watt bath. This is designated as Sample C. Further, as a comparative example, a porous metal body of Ni alone [Celmet manufactured by Sumitomo Electric Industries, Ltd.] was prepared as Sample D.

Example 2 Samples A, B, C and D of Example 1 were cut into a size of 150 mm × 120 mm as a battery electrode substrate. Here, since the samples A and B were cut at the Ni skeleton, Cu was not exposed at the cut end surface,
In Sample C, Cu was exposed. Samples A, B,
Table 1 shows the electric resistance measured between both ends of the long side of the electrode substrate for C and D.

[0013]

[Table 1]

Example 3 A positive electrode of a Ni-hydrogen secondary battery was manufactured by using the porous metal sample A, B, C and D as current collectors according to the following procedure. A porous metal material is press-filled with an active material paste mainly containing nickel hydroxide, smoothed, and then dried at 120 ° C. for 1 hour, and the obtained electrode plate is pressed at a pressure of 1 ton / cm ² to a thickness. It was adjusted to 0.7 mm. This 10 positive electrodes and MmNi (Misch metal nickel) known as negative electrodes
A square sealed Ni-hydrogen battery was constructed by using 10 sheets of hydrogen storage alloy poles and a hydrophilic treated polypropylene nonwoven fabric separator. 2 in a caustic potash solution with a specific gravity of 1.25 as electrolyte
5 g / l of lithium hydroxide was dissolved and used. The battery obtained by the above procedure was used as a porous metal sample A, B, C, D.
Corresponding to A-D, B-D, C-D, and D-D, respectively.

The discharge voltage and the capacity of the batteries at discharge currents of 10 A and 150 A were examined. As a life test, 10A
The capacity retention rate after 500 cycles in discharge was evaluated. Table 2 shows the results. In the batteries C-D, Cu eluted from the cut end surface of the positive electrode plate was deposited on the negative electrode, and the positive electrode and the negative electrode were short-circuited in 483 cycles.

[0016]

[Table 2]

As is clear from these results, A of the present invention
-D and BD show excellent battery characteristics.

[0018]

According to the present invention, a battery electrode substrate having low resistance and excellent corrosion resistance can be realized, and when it is applied to an alkaline secondary battery, charging and discharging can be performed with high output and high efficiency.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a comparative example of the present invention.

[Explanation of symbols]

 1 electrode substrate

Claims (3)

[Claims] 1. An electrode substrate for a battery, which forms an active material holder used as a current collector for a battery, having a three-dimensional network structure in which a skeleton has Cu or a Cu alloy and a surface has Ni or a Ni alloy. An electrode substrate for a battery, which is composed of a body, and partially has a skeleton inside and a surface portion both made of Ni or a Ni alloy. 2. Cu or Cu inside the skeleton of the metal porous body
The alloy part and the Ni or Ni alloy part are formed by sequentially applying a slurry containing Cu or Cu alloy powder and a slurry containing Ni or Ni alloy powder on a porous resin core body in each region and then sintering the slurry. The surface area N
The method for producing a battery electrode substrate, wherein the i or Ni alloy is formed by electroplating. 3. Cu or Cu inside the skeleton of the metal porous body
The alloy part and the Ni or Ni alloy part are formed of Cu or Cu alloy powder and Ni or Ni after the binder resin is applied to the surface of the porous resin core and before the resin is dried and solidified.
Manufacture of a battery electrode substrate, characterized in that the alloy powder is directly applied to each region in order, the resin is fixed and then sintered, and the surface Ni or Ni alloy is formed by electroplating. Method.