JP2000208144A - Battery electrode substrate and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a low-cost electrode substrate for a battery which can sufficiently carry a required active material without using two or more kinds of materials and which can collectively flow the collected electricity with low resistance. provide. SOLUTION: A battery electrode substrate 1 in which a foamed metal body is filled with an active material 3, wherein one side in the thickness direction of the foamed metal body is filled with the active material 3, and the pressure deformation degree is small.
The other side of the layer 5 is the B layer 6 which is not filled with the active material 3 and has a large degree of deformation under pressure. Thus, A that collects electricity
Since it has a two-layer structure of the layer 5 and the B layer 6, which has a small internal electric resistance loss for flowing the electricity, the current collecting effect is large and a large current can be charged and discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a portable electronic device,
The present invention relates to a battery electrode substrate used for a chargeable / dischargeable secondary battery used for an electric vehicle or the like.

[0002]

2. Description of the Related Art As a rechargeable secondary battery, a lead-acid battery has long been used as an automobile battery, but recently, a lightweight and high-capacity battery such as a nickel-cadmium battery, a nickel-hydrogen battery, and a lithium battery has been used. Have been developed and are mainly used for portable electronic devices. Such a secondary battery uses a metal for its electrode substrate, and electricity is stored between an active material supported on the electrode substrate and a counter electrode via a separator. The distance determines the charge / discharge amount. Therefore, the active material is packed into the porous body using a metal porous body for the electrode substrate, or the electrode substrate, the separator and the counter electrode are stacked in a sheet shape, so that more active material is carried in the limited space, In addition, a method of reducing the distance between the electrode substrate and the counter electrode is employed.

[0003] The material range of the metal of the electrode substrate used here is determined by the active material used. Normal,
Currently, nickel is used in nickel-cadmium batteries and nickel-hydrogen batteries, and aluminum is used in lithium batteries. The purpose of this is to prevent the electrode substrate from being corroded by ions or becoming metal ions when the chemical reaction caused by the charge and discharge of the battery ionizes or returns the active material to non-ions, which hinders battery performance. It is.

[0004] The shape of the metal of the electrode substrate is preferably such that the adhesion to the active material is good and the ability to support the active material is large. As a result, porous metal bodies have come to be used. However, even in the case of porous metal bodies obtained by sintering metal powder, a large porosity cannot be obtained, and thus the active material carrying rate is low. Further, those using metal fibers as a non-woven fabric can obtain a large porosity, depending on the thickness of the fibers used, and can take a large loading ratio of the active material. Because of the contact, it is disadvantageous as an electrode skeleton that plays a role of collecting electricity generated in the active material. The most commonly used foam is made of urethane foam, etc., which is made conductive, treated with a metal coating by plating, and then subjected to a roasting furnace to remove resin components such as urethane foam. Metal bodies are the mainstream. In addition, a metal nonwoven fabric is used in which a resin nonwoven fabric is subjected to a conductive treatment, then coated with metal by plating, and the resin is removed in a roasting furnace.

When such a porous metal material is used as an electrode substrate, a paste of an active material such as nickel hydroxide is imprinted on a sheet-like metal electrode plate, and the pores are filled with the active material. At the same time as pressing to the predetermined thickness,
Improves adhesion between active material and metal skeleton. When the active material becomes a battery, every time charge and discharge are repeated, it ionizes or returns to non-ion, thereby taking in ions,
The metal porous body plays a role of supplying and recovering ions as a route. Therefore, a structure in which the metal skeleton penetrates like a blood vessel between the active materials is desirable, and the metal skeleton ideally has a thicker path as a current collector in the direction connected to the battery electrode. is there.

[0006] One of the ideas is Japanese Patent Publication No. 63-2782.
No. 3 discloses the contents, and the contents are shown in FIG. The foamed resin 21 and the porous fibrous resin 22 are integrated, coated with a metal, and then the resin is roasted and removed to produce a two-layer porous metal body, which is used as a foamed metal layer. The fibrous metal layer that supports the substance is an electrode substrate that plays a role of a current collector and reinforcement. When such a structure is used as a battery, the foamed metal layer supporting the active material has a structure in which the active material penetrates into the details of the metal skeleton, and the collected electricity passes through the metal skeleton of the fibrous metal layer to form an electrode. It is convenient to be gathered.

In Japanese Patent Application Laid-Open No. 62-140359, as shown in FIG. 4, a foamed metal having a continuous three-dimensional network pattern, a foamed metal 23 having high porosity on one side and a low porosity on the other side. An electrode substrate which is a foamed metal 24 and is filled with an active material is disclosed. In the case of foamed metal having high porosity on one side and low porosity on the other side, the anode is usually arranged on both sides of foamed urethane coated with carbon, while the anode is arranged only on one side. It is manufactured by increasing the amount of plating on the side where the anode is disposed (low porosity) and decreasing the amount of plating on the opposite side (high porosity). The purpose is to fill the active material with the surface of the high-porosity foam metal 23 facing up, and to maintain this posture until the drying and pressing steps, so that the active material is not dropped and the packing density is increased. It is assumed that.

[0008]

[Problems to be Solved by the Invention] JP-B-63-2782
The electrode substrate having the two-layer structure described in Japanese Patent Publication No. 3 is very difficult to manufacture in terms of quality stability. In other words, there is a quality variation between the foamed resin used as the material and other porous fibrous resins. In particular, in the case of the porous fibrous resin, the distribution of the fibers is not as stable as in the case of the resin foam, and is partially coarse and dense. Is easy to occur. In addition, when the conductive treatment is performed together, the conductive treatment cannot always be performed uniformly due to the difference in the type of the skeleton resin material and the thickness of the skeleton. However, it is difficult to obtain a uniform plating process.

The electrode substrate disclosed in Japanese Patent Application Laid-Open No. 62-140359, in which one side is a foamed metal with high porosity and the other side is a foamed metal with low porosity, is a good invention, but requires a long time for production. Inevitably, costs will increase. In other words, in order to apply a large amount of plating to that surface by plating with the anode disposed only on one side, and to apply the required amount of plating to the other surface, it is necessary to perform plating at a low speed feed. This is because productivity decreases.

Accordingly, the present invention is to provide an electrode substrate which can sufficiently carry a required active material and which can collectively flow the collected electricity with low resistance at low cost.

[0011]

SUMMARY OF THE INVENTION The present invention provides an electrode substrate having a two-layer structure in which a single metal foam is used and a metal skeleton is continuous without using two or more kinds of materials. That is, an electrode substrate in which a foamed metal body is filled with an active material, an active material is filled on one side of a foam metal body that is substantially uniformly manufactured, and a layer having a small degree of pressurization deformation and another layer. The other side is a battery electrode substrate comprising a layer which is not filled with an active material and has a large degree of deformation under pressure. The metal foam used here is preferably mainly composed of nickel, but may be aluminum, gold, silver, copper, platinum, molybdenum, manganese, cobalt, or titanium. The active material preferably has a composition mainly composed of nickel hydroxide.

The metal foam has a metal skeleton having a double structure, the inside of the skeleton being iron, the outside of the skeleton being nickel,
Or those coated with cobalt are also preferable. And, even if the active material has a composition mainly composed of nickel hydroxide and cobalt or a cobalt compound powder,
Get good results.

[0013] In the method of manufacturing an electrode substrate, an active material such as nickel hydroxide is uniformly filled from one side of a foamed metal body, and the filling operation is stopped before the foamed metal body is completely filled in the thickness direction. After drying, by pressing in the thickness direction, one side of the foamed metal body is filled with the active material, and the other side is manufactured in an unfilled state. The foamed metal body used here is preferably obtained by subjecting a resin foam to a conductive treatment and then plating with nickel.Although aluminum, gold, silver, copper, platinum, molybdenum, manganese, cobalt, and titanium can also be used. Obtained in a similar manner. In addition, a double-layer obtained by plating nickel or cobalt on a foamed metal body having an iron skeleton obtained by applying a paste mainly composed of iron powder or iron oxide powder to a resin foam, baking, and roasting. Foamed metal bodies with a structure are also preferred.

The electrode substrate having a two-layer structure composed of an active material-filled layer and an unfilled layer in a state where the metal skeleton thus formed is continuous can be used in the case of manufacturing a cylindrical battery by spirally winding the electrode substrate. Even in the case of manufacturing a prismatic battery by spirally winding and then pressing in the radial direction, the metal skeleton of the active material-unfilled layer is extremely unlikely to break. This is because when a bending external force is applied to the metal skeleton of the active material-filled layer, bending stress and tensile stress are applied to the metal skeleton due to the presence of the active material, and the metal skeleton is easily broken. This is because even if a bending external force is applied to the skeleton, the metal skeleton is hardly broken because the active material is not present and the metal skeleton has a high degree of freedom and almost no tensile stress is applied to the metal skeleton. The electrode substrate having a two-layer structure manufactured as described above has a low internal electric resistance loss because the current-collecting skeleton of the active material-filled layer and the skeleton of the active material-unfilled layer that conducts electricity are integrated. A battery having excellent performance as a battery and stable production quality at low cost can be easily produced.

[0015]

FIG. 1 is an enlarged schematic cross-sectional view of a two-layer electrode substrate 1 of the present invention, which is deformed under pressure in the thickness direction. The active material 3 is filled in the metal foam body on the upper side of the figure, and the A layer 5 has a small degree of pressure deformation of the skeleton 2 of the metal foam body. The active material 3 is not filled in the lower foamed metal body, and the pressure deformation degree of the skeleton 2 of the foamed metal body is large.
Layer 6.

The electricity generated from the A layer 5 of the electrode plate filled with the active material 3 is transmitted to the B layer 6 in which the pores are crushed through the skeleton 2 of the foamed metal body, and the electrode of the battery is formed. (Not shown). The B layer 6, which is not filled with the active material, is made of almost only metal, and the skeleton 2 of the foamed metal body during the pressing is hardly broken, so that an increase in electric resistance is suppressed. That is, a two-layer structure of the A layer 5 for collecting electricity and the B layer 6 with small internal electric resistance loss for passing the electricity has a large current collection effect, and enables a large current to be charged and discharged.

FIG. 2 shows an example of the manufacturing process. The foamed metal body 7 to be prepared is prepared by applying a carbon powder to a resin foam and conducting a conductive treatment to perform plating, or as another method, forming a metal powder or a metal oxide powder into a paste in a resin foam. There is a method of plating after coating, drying and roasting. The plate-shaped foamed metal body 7 is placed horizontally, and nickel hydroxide or nickel hydroxide and cobalt powder are made into a paste with a water-soluble resin (such as carboxymethyl cellulose) and water, and imprinted from above. That is, the pores 4 of the foamed metal body 7 sent in the direction of the arrow at a constant speed are filled with the paste-form active material 3 to a predetermined depth by a pump 8 at a constant pressure. The filling amount of the active material 3 with respect to the thickness of the foamed metal body is adjusted by controlling the amount of the paste to be filled.

After this is dried, it is pressed in the thickness direction of the foamed metal body to a predetermined thickness. As a result, the metal skeleton part forming a nearly spherical foamed space filled with the active material,
It is pushed in the thickness direction and becomes an elliptical sphere. Then, the metal skeleton portion not filled with the active material loses almost space, becomes flat, and is crushed into a metal plate shape.

The electrode substrate having the two-layer structure has a stable production quality, can be easily manufactured at low cost, and has an A layer 5 filled with an active material and collecting electricity, and a B layer 6 flowing electricity. But,
Since it is made of an integral foam metal, the internal electric resistance loss is small. In other words, the A layer 5 carrying the active material allows the active material to penetrate into the details of the metal skeleton and collect the collected electricity there through the flat metal plate-like B layer 6 on the other side, and then to the electrode. As a result, a large current can be discharged.

(Example 1) Nickel-based thickness3.
A foamed metal body of approximately 0 mm is produced at a constant speed, and a constant pressure is applied by a pump, and a paste-like active material mainly composed of nickel hydroxide is imprinted thereon. Was 1.4 mm, and the thickness of the unfilled portion was 1.6 mm. This was pressed so as to have a thickness of 0.7 mm, and an electrode substrate having a metal plate shape on one side filled with an active material and the other side unfilled was obtained. This was cut into a length of 35 mm and a width of 75 mm, and a lead plate was attached by spot welding.

The nickel electrode and Mm known as a partner electrode
Ni (Misch Metal Nickel) -based hydrogen storage alloy electrode, and spirally wound through a polypropylene nonwoven fabric separator that has been subjected to hydrophilic treatment between the two to form an electrode substrate group,
After inserting this into an outer can and injecting the electrolytic solution, the outer can was sealed with a sealing plate to obtain a cylindrical nickel-hydrogen battery. This is No. 1B. In addition, 30 g / l of lithium hydroxide was added to an aqueous caustic potassium solution having a specific gravity of 1.3 as an electrolytic solution.

Example 2 A paste-like active material was applied to a 3.0 mm-thick foamed metal body in which the skeleton of the foamed metal body had a double structure, the inside of the skeleton was coated with iron, and the outside of the skeleton was coated with nickel. The thickness of the imprinted and filled portion was 1.4 mm, and the thickness of the unfilled portion was 1.6 mm. This was pressed so as to have a thickness of 0.7 mm, and an electrode substrate having a metal plate shape on one side filled with an active material and the other side unfilled was obtained. This is vertical 3
The sheet was cut into 5 mm and 75 mm in width, and the lead plate was attached by spot welding. Then, using this electrode substrate, a cylindrical nickel-hydrogen battery was obtained in the same procedure as in Example 1. This is N
o. 2B.

As a comparative example, the thickness is mainly composed of nickel.
After pressing a 0 mm foam metal body to a thickness of 1.4 mm,
A paste-like active material was imprinted over the entire thickness, and this was pressed to a thickness of 0.7 mm. Using this electrode substrate, a cylindrical nickel-hydrogen battery of a comparative example was obtained in the same manner as in the example. This is No. 3B. And
No. 1B-No. Discharge current 1 of 3 types of batteries of 3B
A, 5 A, and 10 A were examined for discharge voltage and capacity. Table 1 shows the results.

[0024]

[Table 1]

From these results, it can be seen that the battery No. of the comparative example. 3B compared to the battery No. In 1B and 2B, it can be seen that the capacity (mAh) is greatly improved as the discharge becomes larger. Similarly, in the battery No. of the comparative example. 3B compared to the battery No. In 1B and 2B, the discharge voltage (V) is improved as the discharge becomes larger. This lowers the internal electric resistance loss of the electrode substrate by collecting electricity from the layer filled with the active material and flowing the electricity to the electrode through the layer deformed under pressure without filling the active material. Because it became possible.

Next, a fixed amount of active material per area was filled in foamed metal bodies having different thicknesses. This makes it possible to change the ratio between the layer filled with the active material and the layer in which the pores are crushed. That is, thickness 2.0,3.
A foamed metal body mainly composed of nickel having a thickness of 0 or 4.0 mm was prepared, and an active material was imprinted thereon in the same manner as in the example, so that the thickness of each of the filling layers was 1.4 mm. These were compressed to a thickness of 0.7 mm. As a result, an electrode substrate was manufactured in which the ratio between the layer filled with the active material and the layer in which the pores were crushed was changed. Table 3 shows these three types of electrode substrates.

[0027]

[Table 2]

Using the three types of electrode substrates shown in Table 2, a cylindrical nickel-hydrogen battery was manufactured in the same procedure as in the embodiment.
Table 3 shows the results of examining the discharge voltage and capacity during the discharge of A, 5A, and 10A.

[0029]

[Table 3]

As a result, when the unfilled layer becomes large and the internal electric resistance loss of the electrode substrate becomes small, the discharge characteristics of a large current increase in both voltage (V) and capacity (mAh), and the effect of lowering the internal electric resistance appears. ing. From these, by changing the thickness of the porous metal body in accordance with the discharge current, an electrode substrate corresponding to the required current amount can be obtained.

[0031]

According to the electrode substrate of the present invention, since the integrally formed foamed metal body is finished in a two-layer structure by filling the active material, the metal skeleton is continuous and the current collecting performance is improved. good. Therefore, an electrode substrate capable of suppressing heat generation due to internal electric resistance and charging / discharging a large power can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a battery electrode substrate according to the present invention.

FIG. 2 is a diagram showing an outline of an example of a manufacturing method of the present invention.

FIG. 3 is a schematic sectional view of a conventional foamed resin and a porous fibrous resin.

FIG. 4 is a schematic cross-sectional view of a prior art foam metal for an electrode substrate.

[Explanation of symbols]

 1. 1. electrode substrate 2. Skeleton of foam metal body Active material 4. Pores 5. A layer 6. B layer 7. 7. Foamed metal body pump

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masasaku Yamanaka 1-1-1, Koyokita-Kita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works F-term (reference) 5H016 AA06 BB05 BB08 CC09 EE01 EE05 HH10 5H017 AA02 AA03 AS02 BB06 BB08 CC01 CC28 DD03 DD05 EE01 EE04 HH09

Claims (4)

[Claims] 1. An electrode substrate for a battery in which a foamed metal body is filled with an active material, wherein one side in a thickness direction of the foamed metal body which is produced substantially uniformly is filled with an active material, and the pressure deformation degree is An electrode substrate for a battery, characterized in that it has a small two-sided structure, the other side is not filled with an active material, the degree of pressure deformation is large, and the metal skeleton of the foamed metal body is continuous. . 2. The foamed metal body is mainly made of nickel,
The battery electrode substrate according to claim 1, wherein the active material has a composition mainly composed of nickel hydroxide. 3. The foam metal body has a double skeleton, the inside of the skeleton is coated with iron, and the outside of the skeleton is coated with nickel or cobalt, and the active material is a powder of nickel hydroxide and cobalt or a cobalt compound. The electrode substrate for a battery according to claim 1, wherein the composition is mainly composed of: 4. An almost uniformly prepared foamed metal body is filled with an active material from one side in the thickness direction, the filling operation is stopped before filling the entire thickness, and then the foamed metal body is reduced in thickness. A method for producing an electrode substrate for a battery, comprising applying pressure in a direction.