JP2010244715A - Electrode substrate for alkaline secondary battery, and electrode for the alkaline secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode substrate and an electrode preventing contact of a positive electrode and a negative electrode, when they are spirally wound by forming the skeleton of three-dimensional net structure so as to make it less apt to pass through a separator. <P>SOLUTION: An electrode substrate 10 for an alkaline secondary battery has three-dimensional net structure, in which the inside is hollow and the tip part 12 of the skeleton 11 exposed to the surface of foam nickel has a spherical or hemispherical outer shape. The spherical or hemispherical outer shape is formed, in such a way that a tip part 12a of a skeleton 11a exposed to the outside of foam resin 10a having three-dimensional net structure is deformed to a spherical or hemispherical tip part 12b of a skeleton 11b exposed to the outside of foam resin 10b by heat treatment, and the foam resin 10b is made electrically conductive; and after electrolytic nickel plating is applied, the foam resin is decomposed and removed by heating. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrode substrate used for an alkaline secondary battery such as a nickel-hydrogen secondary battery or a nickel-cadmium secondary battery, and an electrode using the electrode substrate, and more particularly, has a three-dimensional network structure skeleton. The present invention relates to an electrode substrate for an alkaline secondary battery made of plate-like foamed nickel and an electrode for an alkaline secondary battery using the electrode substrate.

  In recent years, as electronic devices such as mobile phones and portable personal computers (so-called laptop computers) have become cordless and the needs for electrically assisted bicycles have increased, they have been remarkably improved in functionality, size and weight. There is. There is a growing demand for higher capacity for secondary batteries that serve as power sources for these various electronic devices and electric assist bicycles. As a secondary battery serving as a power source for these devices, an alkaline secondary battery such as a nickel-hydrogen secondary battery or a nickel-cadmium secondary battery is generally used. In particular, the nickel-hydrogen storage battery is a secondary battery composed of a nickel positive electrode mainly composed of nickel hydroxide and a hydrogen storage alloy negative electrode mainly composed of a hydrogen storage alloy, and is a high capacity and high reliability alkaline secondary battery. It is popular.

  In this case, nickel positive electrodes for alkaline secondary batteries are roughly classified into two types, a sintered type and a non-sintered type. Here, the sintered positive electrode is obtained by impregnating a nickel sintered substrate having a porosity of about 80% obtained by sintering a conductive core material such as punching metal and nickel powder with a nickel salt solution such as an aqueous nickel nitrate solution. Subsequently, nickel hydroxide as an active material is produced in a porous nickel sintered substrate by impregnating with an alkaline aqueous solution. Since it is difficult for the sintered positive electrode to further increase the porosity of the nickel sintered substrate, the amount of active material cannot be increased, and there is a limit to increasing the capacity.

  On the other hand, a non-sintered positive electrode is produced by filling a foamed nickel substrate with nickel hydroxide as a positive electrode active material, and is widely used as a positive electrode for high-capacity alkaline secondary batteries. Here, the foamed nickel substrate is manufactured by plating the surface of a skeleton of a three-dimensional network structure such as foamed polyurethane with nickel and then removing the three-dimensional network structure. It is made of a metal porous body having a dimensional network structure (for example, nickel foam having a porosity of about 95%). In this non-sintered positive electrode, spherical nickel hydroxide having a large bulk density is used from the viewpoint of increasing the capacity.

  By the way, in an alkaline secondary battery using a non-sintered positive electrode, a cylindrical structure and a square structure are known. Among these, the alkaline secondary battery having a cylindrical structure has a non-sintered nickel positive electrode coated with nickel hydroxide and a hydrogen storage alloy negative electrode coated with a hydrogen storage alloy wound in a spiral shape with a separator interposed therebetween. The electrode group formed in this manner, an electrolytic solution, and a cylindrical outer can that also serves as a negative electrode terminal that accommodates the electrode group and the electrolytic solution, and the outermost periphery of the electrode group is a negative electrode that contacts the inner surface of the cylindrical outer can It is made like that.

  In recent years, in this type of cylindrical secondary alkaline battery, the capacity of each electrode has been increased to increase the capacity. Therefore, for example, Patent Document 1 (Japanese Patent Laid-Open No. 3-59958) discloses that the distance between the positive electrode and the negative electrode is shortened and the weight of the separator is reduced to increase the amount of active material of each electrode. Proposed.

JP-A-3-59958

  However, when the weight of the separator is reduced as proposed in Patent Document 1, there is a problem that the positive electrode and the negative electrode are in contact with each other, that is, an internal short circuit is likely to occur, and the occurrence rate of the internal short circuit is increased. It came to occur. This is because when the separator is reduced in weight, a non-sintered nickel positive electrode coated with nickel hydroxide and a hydrogen storage alloy negative electrode coated with a hydrogen storage alloy are wound in a spiral shape with a separator interposed therebetween. This is because the skeleton of the porous metal body (foamed nickel) having a three-dimensional network structure used for the non-sintered nickel positive electrode breaks through the low-weight separator and comes into contact with the hydrogen storage alloy negative electrode. .

  Therefore, the present invention has been made to solve the above-described problem, and the skeleton of the porous metal body (foamed nickel) having a three-dimensional network structure is formed in a spiral shape so that it does not easily penetrate the separator. An object of the present invention is to provide an electrode substrate for an alkaline secondary battery excellent in reliability by preventing the positive electrode and the negative electrode from coming into contact with each other when wound on, and an electrode for an alkaline secondary battery using this electrode substrate. It is.

  In order to achieve the above object, an alkaline secondary battery electrode substrate made of plate-like nickel foam having a three-dimensional network structure skeleton of the present invention has a hollow three-dimensional network structure inside the skeleton. The tip portion of the skeleton exposed to the outside of the plate-like nickel foam having the skeleton has an outer shape of a spherical shape, a hemispherical shape, or a flexible needle shape.

  In this case, the outer shape of a spherical, hemispherical or flexible needle shape is obtained by subjecting the plate-like foamed resin having a three-dimensional network structure to the outside of the skeleton exposed to the outside by heat treatment or chemical treatment. By transforming the outer shape of the tip of the skeleton exposed to the outside of the resin into a spherical, hemispherical or flexible needle shape, imparting conductivity, applying electrolytic nickel plating, and then heating It is desirable that the resin is formed by decomposing and removing the foamed resin.

  Further, for an alkaline secondary battery formed by filling a main active material made of nickel hydroxide or higher-order nickel hydroxide into an electrode substrate made of plate-like foamed nickel having a three-dimensional network structure skeleton of the present invention. The electrode is hollow inside the skeleton of the three-dimensional network structure, and the outer end of the skeleton exposed to the outside of the plate-like foam nickel provided with the skeleton has a spherical, hemispherical or flexible needle shape. And a main active material made of nickel hydroxide or higher-order nickel hydroxide is filled in the gaps between the skeletons.

  Also in this case, the outer shape of a spherical, hemispherical or flexible needle shape is obtained by heating or chemical treatment of the tip of the skeleton exposed outside the plate-like foamed resin having a three-dimensional network structure. The outer shape of the skeleton exposed to the outside of the foamed resin is deformed so that it becomes spherical, hemispherical, or flexible needle-shaped, and then imparted conductivity, and after applying electrolytic nickel plating, heating Therefore, it is desirable that the foamed resin be formed by decomposing and removing.

  In the present invention, since the skeleton of the porous metal body (foamed nickel) having a three-dimensional network structure is difficult to penetrate the separator, the positive electrode and the negative electrode are prevented from coming into contact when wound in a spiral shape. It is possible to provide an alkaline secondary battery electrode substrate and an alkaline secondary battery electrode that are excellent in reliability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is an enlarged view showing a part of the skeleton of the surface portion of the polyurethane foam sheet of the present invention and a part of the skeleton of the surface portion of the electrode substrate for an alkaline secondary battery. FIG. 1B is a side view schematically showing a part of the side surface of the main part of the skeleton before the heat treatment of the polyurethane sheet, and FIG. 1B shows the main part of the skeleton after the heat treatment of the foamed polyurethane sheet of Example 1. FIG. 1C is a side view schematically showing a part of the side surface of the main part of the skeleton of the electrode substrate for an alkaline secondary battery of Example 1. FIG. . FIG. 2 (a) is an enlarged view showing a part of the skeleton of the surface part of the foamed polyurethane sheet of the present invention and a part of the skeleton of the surface part of the electrode substrate for an alkaline secondary battery. FIG. FIG. 2B is a side view schematically showing a side surface of a part of the main part of the skeleton before chemical treatment of the polyurethane sheet, and FIG. 2B is a diagram of the main part of the skeleton after chemical treatment of the foamed polyurethane sheet of Example 2. FIG. 2C is a side view schematically showing a part of the side surface of the main part of the skeleton of the alkaline secondary battery electrode substrate of Example 2. . It is a figure which expands and shows a part of surface part of the frame | skeleton of the foaming polyurethane sheet of a comparative example, and a part of surface part of the frame | skeleton of the electrode substrate for alkaline secondary batteries, FIG.3 (a) is a foaming polyurethane of a comparative example FIG. 3B is a side view schematically showing a part of the side surface of the main part of the skeleton of the sheet, and FIG. 3B is a schematic side view of a part of the main part of the skeleton of the alkaline secondary battery electrode substrate of the comparative example. FIG. It is sectional drawing which expands and shows typically the principal part of the surface part of the electrode for alkaline secondary batteries, 4 (a) is the electrode substrate for alkaline secondary batteries of Example 1 shown in FIG.1 (c). It is sectional drawing which shows typically a cross section of a part of main part of the surface part of the used electrode for alkaline secondary batteries, FIG.4 (b) is the alkali secondary of Example 2 shown in FIG.2 (c). It is sectional drawing which shows typically a cross section of a part of principal part of the surface part of the electrode for alkaline secondary batteries using a battery electrode substrate, and FIG.4 (c) is a comparative example shown in FIG.3 (b). It is sectional drawing which shows typically a partial cross section of the principal part of the surface part of the electrode for alkaline secondary batteries using the electrode substrate for alkaline secondary batteries. It is sectional drawing which shows the alkaline secondary battery of this invention typically.

  Next, embodiments of the present invention will be described in detail below. However, the present invention is not limited to these embodiments, and can be appropriately modified and implemented without departing from the scope of the present invention.

1. Foam nickel substrate (metal porous body with three-dimensional network structure)
(1) Example 1
The foamed nickel substrate 10 of Example 1 has a three-dimensional network structure skeleton 11 that is hollow (not shown). And the front-end | tip part 12 of the frame | skeleton 11 exposed on the surface of this board | substrate 10 is formed so that the external shape may become a spherical shape or a hemispherical shape, as shown in FIG.1 (c). Hereinafter, a manufacturing method in which the outer shape of the distal end portion 12 of the skeleton 11 is spherical or hemispherical will be described in detail.

  First, a polyurethane foam sheet (not shown) (for example, a sheet having a thickness of 1.0 mm to 2.0 mm is preferable, and a sheet having a thickness of 1.7 mm is used here) 10a is prepared. In this case, since the surface of the polyurethane foam sheet 10a is a cut surface, as shown in FIG. 1 (a), the tip 12a of the skeleton 11a exposed on the surface has a protruding shape with sharp corners. ing. Then, hot air (for example, preferably at a temperature of 170 to 230 ° C., preferably 1 to 5 seconds) is uniformly applied to the surface to melt the tip 12a of the skeleton 11a. As a result, as shown in FIG. 1 (b), a foamed polyurethane sheet 10b in which a part of the skeleton 11a becomes a deformed skeleton part 11b and the outer shape of the tip part 12b is spherical or hemispherical is obtained. It will be.

  Next, nickel is vapor-deposited by PVD (Physical Vapor Deposition) method on the deformed skeleton part 11b and the foamed polyurethane sheet 10b whose tip part 12b is spherical or hemispherical, and the inner skeleton (not shown) of the foamed polyurethane sheet 10b is shown. ), Conductivity was imparted to the surface of the deformed skeleton 11b exposed on the surface and the tip 12b having a spherical or hemispherical shape. Thereafter, electrolytic nickel plating is applied to the foamed polyurethane sheet 10b having conductivity imparted to the inner skeleton (not shown), the deformed skeleton portion 11b exposed on the surface, and the spherical or hemispherical tip portion 12b. The inner skeleton (not shown), the deformed skeleton portion 11b exposed on the surface and the surface of the tip portion 12b that is spherical or hemispherical, preferably a nickel plating layer (for example, having a thickness of 5 μm to 20 μm, Here, the sheet is 10 μm).

Next, the obtained sheet was subjected to thermal decomposition treatment (for example, preferably at 700 ° C. for about 10 minutes) to decompose and remove the foamed polyurethane sheet 10a and anneal the nickel plating layer. As a result, the inside has a three-dimensional network structure skeleton 11 that is hollow (not shown), and the distal end portion 12 of the skeleton 11 exposed on the surface has an outer shape as shown in FIG. The foamed nickel substrate 10 of Example 1 having a spherical or hemispherical shape and a basis weight of 350 g / m ² is formed.

  In Example 1 described above, foaming is performed in order to melt the tip 12a of the skeleton 11a exposed on the surface of the foamed polyurethane sheet 10a so that the outer shape of the tip 12a of the skeleton 11a is spherical or hemispherical. An example has been described in which hot air (for example, at a temperature of 170 to 230 ° C., preferably 1 to 5 seconds) is uniformly applied to the surface of the polyurethane sheet 10a. However, in order to melt the distal end portion 12a of the skeleton 11a exposed on the surface of the polyurethane foam sheet 10a, not only hot air but other means can be used. In this case, for example, the polyurethane foam sheet 10a is passed between a pair of heating rollers heated to a predetermined temperature (for example, 170 ° C. to 230 ° C., preferably 200 ° C.). The front and back surfaces of 10a may be heated to melt the tip 12a of the skeleton 11a exposed on the surface, and the outer shape of the tip 12a of the skeleton 11a exposed on the surface may be spherical or hemispherical.

(2) Example 2
Next, the foamed nickel substrate 20 of Example 2 will be described. The foamed nickel substrate 20 of Example 2 has a three-dimensional network structure skeleton 21 that is hollow (not shown). And the front-end | tip part 22 of the frame | skeleton 21 exposed on the surface of this board | substrate 20 has a softness | flexibility, and as shown in FIG.2 (c), the external shape of the front-end | tip part is formed in the shape sharpened like a needle. Yes. Hereinafter, a manufacturing method in which the distal end portion 22 of the skeleton 21 exposed on the surface has flexibility and the outer shape thereof becomes a needle-like shape will be described in detail.

  First, a foamed polyurethane sheet (not shown) (for example, a sheet having a thickness of 1.0 mm to 2.0 mm is preferable, and a sheet having a thickness of 1.7 mm is used here) 20a is prepared. In this case, since the surface of the polyurethane foam sheet 20a is a cut surface, as shown in FIG. 2 (a), the tip 22a of the skeleton 21a exposed on the surface has a protruding shape with sharp corners. ing. Then, concentrated sulfuric acid is impregnated on the surface of the polyurethane foam sheet 20a (in the range of 10 to 30% of the thickness from the surface of the sheet 20a). As a result, as shown in FIG. 2B, a part of the skeleton 21a exposed on the surface becomes a deformed skeleton part 21b, and the needle-like part 22b whose outer shape is pointed like a needle is formed. The resulting foamed polyurethane sheet 20b is obtained.

  Next, a part of the skeleton 21a exposed on the surface becomes a deformed skeleton part 21b, and a foamed polyurethane sheet 20b in which the outer shape of the distal end part 22b has a needle-like shape is applied to the PVD (Physical Vapor Deposition) method. The inner surface of the foamed polyurethane sheet 20b (not shown) 21a, the deformed skeleton 21b exposed on the surface, and the surface of the foamed polyurethane sheet 20b in which the tip 22b is needle-shaped are deposited by nickel. Granted. Thereafter, the foamed polyurethane sheet 20b to which conductivity is imparted is subjected to electrolytic nickel plating, so that the inner skeleton (not shown), the deformed skeleton portion 21b exposed on the surface, and the surface of the needle-like tip portion 22b are formed. A sheet on which a nickel plating layer (for example, one having a thickness of 5 μm to 20 μm is preferable, here 10 μm) is formed.

Next, the obtained sheet was subjected to a thermal decomposition treatment (for example, preferably at 700 ° C. for about 10 minutes) to decompose and remove the foamed polyurethane sheet 20b and to anneal the nickel plating layer. Thereby, the inside has a three-dimensional network structure skeleton 21 that is hollow (not shown), and the tip 22 of the skeleton 21 exposed on the surface has flexibility, as shown in FIG. 2 (c). Thus, the foamed nickel substrate 20 of Example 2 is formed in which the outer shape of the tip is pointed like a needle and the basis weight is 350 g / m ² .

  In Example 2 described above, a part of the skeleton 21a exposed on the surface of the polyurethane foam sheet 20a becomes a deformed skeleton part 21b, and the outer shape of the distal end part 22b has a needle-like shape. As described above, the example in which the foamed polyurethane sheet 20a is impregnated with concentrated sulfuric acid has been described. However, even when impregnated with a chemical such as phenol instead of concentrated sulfuric acid, a part of the skeleton 21a exposed on the surface of the polyurethane foam sheet 20a becomes a deformed skeleton part 21b, and the outer shape of the front end part 22b. Can be obtained as a foamed polyurethane sheet 20b having a needle-like shape.

(3) Comparative Example Next, the foamed nickel substrate 30 of the comparative example will be described. The foamed nickel substrate 30 of the comparative example has a three-dimensional network structure skeleton 31 that is hollow (not shown). And the front-end | tip part 32 of the frame | skeleton 31 exposed on the surface of this board | substrate 30 is a protrusion shape with the sharp corner | angular part, as shown in FIG.3 (c). Below, the manufacturing method is explained in full detail. First, a polyurethane foam sheet (not shown) 30a (for example, a sheet having a thickness of 1.0 mm to 2.0 mm is preferable, and a sheet having a thickness of 1.7 mm is used here) 30a is prepared. In this case, since the surface of the polyurethane foam sheet 30a is a cut surface, as shown in FIG. 3 (a), the tip 32a of the skeleton 31a exposed on the surface has a protruding shape with sharp corners. ing.

  Next, nickel was deposited on the foamed polyurethane sheet 30a by a PVD (Physical Vapor Deposition) method to impart conductivity to the internal skeleton (not shown) of the foamed polyurethane sheet 30a and the surface of the skeleton 31a exposed on the surface. Thereafter, electrolytic nickel plating is applied to the foamed polyurethane sheet 30a having conductivity imparted to each skeleton surface, and a nickel plating layer (for example, thickness) is formed on the surface of the inner skeleton (not shown) and the skeleton 31a exposed on the surface. Is preferably 5 μm to 20 μm, and is 10 μm here).

Subsequently, the obtained sheet was subjected to a thermal decomposition treatment (for example, preferably at 700 ° C. for about 10 minutes) to decompose and remove the foamed polyurethane sheet 30a and to anneal the nickel plating layer. As a result, the inside has a skeleton 31 having a three-dimensional network structure that is hollow (not shown), and the tip 32 of the skeleton 31 exposed on the surface has a sharp corner as shown in FIG. A foamed nickel substrate 30 of a comparative example having a protrusion shape and a basis weight of 350 g / m ² is formed.

2. Nickel positive electrode The nickel positive electrode 40a (40b, 40c) is filled with a paste containing a positive electrode active material mainly composed of a predetermined amount of nickel hydroxide on the foamed nickel substrate 10 (20, 30) having the above-described configuration. Is formed. In this case, the one using the foamed nickel substrate 10 becomes the nickel positive electrode 40a, the one using the foamed nickel substrate 20 becomes the nickel positive electrode 40b, and the one using the foamed nickel substrate 30 becomes the nickel positive electrode 40c. Next, an example in which the nickel positive electrode 40a (40b, 40c) is produced using the foamed nickel substrate 10, 20, 30 having the above-described configuration will be described below.

  First, 100 parts by mass of nickel hydroxide powder, if necessary, a conductive material, 0.05 parts by mass of carboxymethyl cellulose (CMC) as a binder, 0.05 parts by mass of sodium polyacrylate, polytetrafluoroethylene A paste is prepared by adding a dispersion of (PTFE) (specific gravity 1.5, solid content 60% by mass) to 0.1 part by mass in terms of solid content and mixing with water. Here, as the nickel hydroxide powder, nickel hydroxide powder in which one or more metals selected from zinc and cobalt are eutectic, or non-eutectic nickel hydroxide powder can be used.

  Note that a conductive layer containing cobalt oxyhydroxide (CoOOH) may be formed on the surface of the nickel hydroxide powder, but when a conductive layer is formed, it is necessary to add a conductive material. Absent. Examples of the conductive material include metallic cobalt and cobalt compounds (cobalt oxide such as CoO and cobalt hydroxide such as Co (OH)), and one or more of these can be used. Can be used. In this case, the conductive material can be added to the paste in the form of a powder or a layered material covering the surface of nickel hydroxide.

Then, after filling each foamed nickel substrate 10 (20, 30) formed as described above with the paste prepared as described above so that the active material has a packing density of 2.5 g / cm ³ , After drying at room temperature and rolling to a predetermined thickness (for example, 0.65 mm), the nickel positive electrode 40a (40b, 40c) is manufactured by cutting to a predetermined dimension (for example, 100 mm). One end of the obtained nickel positive electrode 40a (40b, 40c) is formed by removing the filled paste by ultrasonic vibration to form a connection portion 41 that is welded to a positive electrode current collector 42 described later. Like to do.

3. Hydrogen Storage Alloy Negative Electrode A hydrogen storage alloy negative electrode 50 using a hydrogen storage alloy as a negative electrode active material is a paste containing hydrogen storage alloy powder as a negative electrode active material on the surface of a conductive core 51 made of a porous substrate (punching metal). Is formed by filling. In this case, the conductive core 51 is made of a nickel-plated soft steel porous substrate (punching metal), and at one end, the filled paste is removed by ultrasonic vibration. Thus, a connection portion 51 that is welded to a negative electrode current collector 52 described later is formed.

The hydrogen storage alloy may be anything as long as it can electrochemically store and release hydrogen. For example, LaNi ₅ , MmNi ₅ (Mm is misch metal), LmNi ₅ (Lm is lanthanum enriched) Misch metal), a multi-element type in which a part of Ni of these alloys is substituted with at least one element selected from Al, Mn, Co, Ti, Cu, Zn, Zr, Cr, B, etc. be able to. Above all, the general formula _{LmNi v Co w Mn x Al y} Zr z ( However, Lm, at least one or more rare earth elements, the atomic ratio v, w, x, y, the total value of z is 5.0 ≦ v + w + x + y + z ≦ 5 It is preferable to use those represented by (4). The average particle size of the hydrogen storage alloy powder is preferably in the range of 20 to 70 μm.

Next, an example of a production example of the hydrogen storage alloy negative electrode 50 of the embodiment as described above will be described below. First, hydrogen storage alloy powder (for example, LmNi _4.0 Coi _0.4 Mn _0.3 Al _0.3 ) and 100 parts by mass of this hydrogen storage alloy powder, 0.5 parts by mass of sodium polyacrylate as a binder, carboxymethylcellulose ( CMC) 0.125 parts by mass, polytetrafluoroethylene (PTFE) dispersion (specific gravity 1.5, solid content 60% by mass) 2.5 parts by mass in terms of solid content, and carbon black as a conductive agent. A hydrogen storage alloy paste is prepared by mixing 0 part by mass and 50 parts by mass of water.

Next, a conductive core 51 made of a nickel-plated soft steel porous substrate (punching metal) is prepared, and a predetermined packing density (for example, 5.0 g / cm ³ ) is provided in the conductive core 51. The above-described hydrogen storage alloy paste is applied so that After drying, the film is rolled to a predetermined thickness, and then cut to a predetermined size to produce a hydrogen storage alloy negative electrode 50. In addition, one end of the obtained hydrogen storage alloy negative electrode 50 is connected to be welded and connected to a negative electrode current collector 52 described later by removing the filled paste by ultrasonic vibration to expose the core 51. The part is formed.

  In addition to the sodium polyacrylate, carboxymethyl cellulose (CMC), and polytetrafluoroethylene (PTFE) described above, methyl cellulose, polyvinyl alcohol (PVA), and styrene butadiene rubber (SBR) may be used as the binder. . Further, as the conductive agent, graphite may be used instead of the above-described carbon black. Furthermore, as the porous substrate, in addition to the punching metal described above, an expanded metal, a nickel net, or the like may be used.

4). Nickel-hydrogen storage battery Next, an example of producing a nickel-hydrogen storage battery using the nickel positive electrodes 40a, 40b, 40c and the hydrogen storage alloy negative electrode 50 having the above-described configuration will be described below. First, nickel positive electrodes 40a, 40b, 40c and a hydrogen storage alloy negative electrode 50 are prepared, and a separator 60 is interposed between the nickel positive electrodes 40a, 40b, 40c and the hydrogen storage alloy negative electrode 50 to form a laminate. As the separator 60, for example, a polyamide fiber nonwoven fabric, a polyolefin fiber nonwoven fabric such as polyethylene or polypropylene, or a nonwoven fabric provided with a hydrophilic functional group may be used.

  Then, after winding the obtained laminated body in a spiral shape to form a spiral electrode group, the core body 51 exposed and projected at the lower end of the spiral electrode group is welded to the negative electrode current collector 52. The connection portion 41 protruding from the upper end portion of the spiral electrode group is welded to the positive electrode current collector 42. Thereafter, a spirally wound electrode group to which the positive electrode current collector 42 and the negative electrode current collector 52 are welded is a bottomed cylindrical outer can in which iron is plated with nickel (the outer surface of the bottom surface serves as a negative electrode external terminal) 70 Store in. As a result, the hydrogen storage alloy negative electrode 50 located on the outermost periphery of the spiral electrode group comes into close contact with the inner peripheral surface of the outer can 70.

  Thereafter, the negative electrode current collector 52 is welded to the bottom surface of the outer can 70, and then the positive electrode lead 43 extending from the positive electrode current collector 42 constitutes the bottom of the sealing body 80 having the insulating gasket 73 attached to the outer peripheral portion. Weld to the sealing plate 81. The sealing body 80 is provided with a positive electrode cap 82 serving as a positive electrode terminal, and a valve body 83 and a spring 84 that are deformed when a predetermined pressure is reached in a space formed by the sealing plate 81 and the positive electrode cap 82. The pressure valve which consists of is arrange | positioned. Next, after forming the annular groove 71 on the outer periphery of the upper portion of the outer can 70, the electrolytic solution was injected, and the outer peripheral portion of the sealing body 80 was mounted on the annular groove 71 formed on the upper portion of the outer can 70. An insulating gasket 73 is placed.

  Then, the nickel-hydrogen storage battery is produced by caulking the opening edge 72 of the outer can 70. In this case, an alkaline electrolyte was injected into the outer can 70 to produce AA-sized cylindrical nickel-hydrogen storage batteries A, B, and C. In addition, the thing using the nickel positive electrode 40a was made into the nickel-hydrogen storage battery A, the thing using the nickel positive electrode 40b was made into the nickel-hydrogen storage battery B, and the thing using the nickel positive electrode 40c was made into the nickel-hydrogen storage battery C. In this case, examples of the alkaline electrolyte include a mixed aqueous solution of sodium hydroxide (NaOH) and lithium hydroxide (LiOH), a mixed aqueous solution of potassium hydroxide (KOH) and lithium hydroxide (LiOH), and potassium hydroxide. A mixed aqueous solution of (KOH), lithium hydroxide (LiOH), and sodium hydroxide (NaOH) may be used.

5). Measurement of short-circuit occurrence rate Next, 1000 nickel-hydrogen batteries A, B, and C were prepared, and then a short-circuit test was performed to determine the occurrence rate of short-circuit. As shown in Table 1 below, As a result. In this case, the short circuit test was performed as follows. That is, after injecting the electrolytic solution, the battery voltage was measured, and the battery having a battery voltage of 0 mV was defined as a battery in which a short circuit occurred.

  As is clear from the results in Table 1 above, it can be seen that the nickel-hydrogen storage batteries A and B have no short circuit, whereas the nickel-hydrogen storage battery C has a short circuit. In the nickel-hydrogen storage battery C, since the foamed polyurethane sheet 30a is not subjected to heat treatment or chemical treatment, the surface of the foamed polyurethane sheet 30a is a cut surface, and the tip of the skeleton 31a exposed on the surface. The portion 32a has a protrusion shape with sharp corners. For this reason, when it is set as a spiral electrode group, it is thought that the positive electrode 40 and the negative electrode 50 contacted and the short circuit arose.

  On the other hand, in the nickel-hydrogen batteries A and B, the foamed polyurethane sheet 10a is subjected to heat treatment (hot air treatment or heated roller treatment), and the foamed polyurethane sheet 20a is subjected to chemical treatment (concentrated sulfuric acid treatment or phenol treatment). Has been. For this reason, in the nickel substrate 10, the outer shape of the tip 12 of the skeleton 11 exposed on the surface is spherical or hemispherical. Moreover, in the nickel substrate 20, the front-end | tip part 22 of the frame | skeleton 21 exposed on the surface has a softness | flexibility, and the external shape of the front-end | tip part becomes a needle-like shape. Thereby, when it was set as the spiral electrode group, it can be prevented that the positive electrode 40 and the negative electrode 50 were in direct contact, and the occurrence of a short circuit could be prevented.

  In the above-described embodiment, an example in which the electrode substrate for an alkaline secondary battery and the electrode for an alkaline secondary battery of the present invention are applied to a nickel-hydrogen storage battery has been described. However, the electrode substrate for an alkaline secondary battery of the present invention is described. The electrode for the alkaline secondary battery is not limited to the nickel-hydrogen storage battery, but can be applied to other alkaline secondary batteries such as a nickel-cadmium storage battery.

DESCRIPTION OF SYMBOLS 10a ... Polyurethane sheet before heat treatment, 11a ... Skeleton exposed on the surface, 12a ... Tip portion of skeleton exposed on the surface, 10b ... Polyurethane sheet after heat treatment, 11b ... Skeleton exposed on the surface after heat treatment, 12b ... The tip of the skeleton exposed on the surface after the heat treatment, 10 ... nickel foam of Example 1, 11 ... the skeleton exposed on the surface, 12 ... the tip of the skeleton exposed on the surface, 20a ... the foamed polyurethane sheet before chemical treatment, 21a: skeleton exposed on the surface, 22a: tip of the skeleton exposed on the surface, 20b: foamed polyurethane sheet after chemical treatment, 21b: skeleton exposed on the surface after chemical treatment, 22b ... exposed on the surface after chemical treatment 20 ... nickel foam of Example 2, 21 ... skeleton exposed on the surface, 22 ... skeleton tip exposed on the surface, 40a, 40b Nickel positive electrode, 41 ... connection portion, 42 ... positive electrode current collector, 43 ... positive electrode lead, 50 ... hydrogen storage alloy negative electrode, 51 ... negative electrode conductive core, 52 ... negative electrode current collector, 60 ... separator, 70 ... exterior Can, 71 ... annular groove, 72 ... opening edge, 73 ... insulating gasket, 80 ... sealing body, 81 ... sealing plate, 82 ... positive electrode cap, 83 ... valve plate, 84 ... spring

Claims (4)

An electrode substrate for an alkaline secondary battery comprising a plate-like foamed nickel having a three-dimensional network structure skeleton,
The inside of the skeleton of the three-dimensional network structure is hollow, and the tip of the skeleton exposed to the outside of the plate-like nickel foam provided with the skeleton has an outer shape that is spherical, hemispherical, or flexible needle-like. An electrode substrate for an alkaline secondary battery.   The outer shape of the spherical, hemispherical or flexible needle shape is a plate-like foamed resin having a three-dimensional network structure. The outer shape of the skeleton exposed to the outside is deformed to be spherical, hemispherical, or flexible needle-like, and then imparted with conductivity, subjected to electrolytic nickel plating, and then heated to form the foam. 2. The electrode substrate for an alkaline secondary battery according to claim 1, wherein the electrode substrate is formed by decomposing and removing a resin. An electrode for an alkaline secondary battery formed by filling a main active material made of nickel hydroxide or higher-order nickel hydroxide into a plate-like foamed nickel electrode substrate having a three-dimensional network structure skeleton,
The inside of the skeleton of the three-dimensional network structure is hollow, and the tip of the skeleton exposed to the outside of the plate-like nickel foam provided with the skeleton has an outer shape that is spherical, hemispherical, or flexible needle-like. And
An electrode for an alkaline secondary battery, wherein a gap between the skeletons is filled with a main active material made of nickel hydroxide or higher-order nickel hydroxide.   The outer shape of the spherical, hemispherical or flexible needle shape is obtained by heating or chemical treatment of the tip of the skeleton exposed to the outside of the plate-like foam resin having a three-dimensional network structure. By imparting conductivity after deforming the outer shape of the distal end of the skeleton exposed to the outside into a spherical, hemispherical or flexible needle shape, and after applying electrolytic nickel plating, heating, The electrode for an alkaline secondary battery according to claim 3, wherein the electrode is formed by decomposing and removing the foamed resin.

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