HK1020637B - Cylindrical alkaline storage battery and manufacturing method of the same - Google Patents

Description

Cylindrical alkaline storage battery using non-sintered electrode and method for manufacturing the same

The technical field is as follows:

the present invention relates to alkaline storage batteries such as nickel-metal hydride storage batteries, nickel-cadmium storage batteries, and nickel-zinc storage batteries, and more particularly to conductive connections between electrodes and current collectors, the electrodes having active material coated on active material carriers.

Background art:

at present, electrodes used for alkaline storage batteries such as nickel-cadmium storage batteries, nickel-hydrogen storage batteries, and nickel-zinc storage batteries are often used as so-called sintered electrodes in which a nickel powder is sintered on a core such as a punched metal to form a sintered substrate, and the substrate is immersed in a solution such as a nickel salt or a cadmium salt to convert the active material into an alkaline substance by an alkaline treatment. When a sintered substrate having high porosity is used, the mechanical strength of the sintered substrate is weakened, and practically, porosity of only about 80% can be used at the maximum, and since a core such as a punched metal is required, the packing density of an active material is low, and it is difficult to realize an electrode having high energy density. Further, since the pore size of the sintered substrate is 10 μm or less, the method is limited to a solution impregnation method or an electro-impregnation method which requires a plurality of repetitions of a filling step of the active material, and thus has a problem that the filling step is complicated and the production cost is high.

On the other hand, in order to improve these disadvantages, a so-called non-sintered electrode, in which a slurry-like active material is directly filled into a metal porous body (active material carrier) having a three-dimensional mesh structure such as a metal fiber sintered body or foamed nickel (nickel sponge), has been the mainstream. The porous metal body having such a three-dimensional mesh structure has a porosity as high as about 95%, and can be filled with an active material at a high density, thereby achieving a high-capacity battery, and the non-sintered electrode is obtained by directly filling the active material into the porous metal body, thereby eliminating the need for troublesome treatment for forming an active material and facilitating the production.

In such a non-sintered electrode, since the porous metal body having a three-dimensional mesh structure has no core, various methods for electrically connecting the electrode and the battery terminal, which are formed by filling the porous metal body with an active material, have been proposed. For example, in japanese patent application laid-open No. 61-218067, when an electrode is manufactured using a felt-like sintered body of metal fibers (metal fiber sintered body) as an electrode support, it is proposed to integrate a felt-like body of metal fibers and a conductive auxiliary body composed of a mesh-like body, punched metal, wire, flat plate, or the like by sintering, thereby improving the mechanical strength of the felt-like body of metal fibers and improving the current collecting performance.

However, there is a problem in that the metal fiber sintered body is formed by binding fine metal fibers (for example, having a wire diameter of 10 μm) in a long shape in a longitudinal direction of the electrodes, and after the active material is coated on the metal fiber sintered body, the positive and negative electrodes are wound in a spiral shape with a separator interposed therebetween, the fine metal fibers may be broken at the time of winding, and the broken fiber pieces pierce the separator to cause electrical connection between the positive and negative electrodes, thereby causing an internal short circuit.

On the other hand, in an electrode using foamed nickel as an electrode support, when the foamed nickel is coated with an active material and then the positive and negative electrodes are spirally wound in a spiral shape with a separator interposed therebetween, the foamed nickel itself is not cut. However, in order to collect current from the electrode, a part of the active material of the electrode is peeled off to expose the nickel foam, and a tongue-shaped current collecting tab is welded to the exposed portion. Since the current collecting performance at the tongue-shaped current collecting tab is not good, a voltage drop occurs at the current collecting tab when a large current is discharged.

Thus, japanese patent application laid-open No. 62-139251 proposes a so-called tab-less battery in which an end portion of an electrode having foamed nickel as an electrode support is compressed in a width direction to form a dense layer, and the dense layer after the compression is welded to a disk-shaped guide piece arranged perpendicular to an electrode surface. The electrode proposed in this japanese patent application laid-open No. 62-139251 is formed by using a foamed metal as an electrode support, and the foamed metal itself is not cut even if it is wound in a spiral shape, and the current collecting performance can be improved because the end of the electrode is welded to a disk-shaped lead piece.

However, the electrode proposed in japanese patent application laid-open No. 62-139251 has a problem that, because of poor flexibility of the dense layer formed by compressing the end portion of the electrode in the width direction, when the positive and negative electrodes are wound around the separator, a part of the dense layer is broken to generate burrs, and the burrs pierce the separator to cause an internal short circuit. Further, since the entire electrode has both a soft portion and an inflexible portion, it is difficult to wind the positive and negative electrodes with the same pressure, and thus there is a problem that uniform pressure cannot be applied to the electrode body at the time of winding.

In addition, it is also possible to form a portion not filled with the active material on the end surface of the electrode support made of nickel foam, and weld a strip-shaped metal plate as an electrode to the active material-filled portion. However, when the electrode formed in this way is wound in a spiral shape together with the counter electrode via the separator, the ribbon-shaped metal plate is not flexible, and thus a part of the ribbon-shaped metal plate is bent into an angular shape and contacts the counter electrode, which causes an internal short circuit.

The invention content is as follows:

therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an electrode body having excellent current collecting performance without causing internal short-circuiting even when a porous metal body having a three-dimensional mesh structure is used as an active material carrier and wound in a spiral shape.

The present invention is a cylindrical alkaline storage battery using a non-sintered electrode, which is formed by housing an electrode body, which is formed by winding a paste-like active material on an active material carrier having a three-dimensional mesh structure made of foamed nickel, and winding the electrode body into a spiral shape with a separator interposed therebetween, in a cylindrical metal outer can serving also as the other terminal, and connecting an end portion of the non-sintered electrode to a disk-shaped current collecting portion having a current collector connected to a lead-out portion of a sealing body sealing an opening of the outer can, and is characterized in that an active material non-filled portion is formed in a longitudinal direction along one end portion of the active material carrier having a three-dimensional mesh structure constituting the non-sintered electrode, a porous metal plate is welded to the active material unfilled portion along the longitudinal direction of one end of the active material carrier, and the end of the porous metal plate is welded to a substantially disk-shaped current collecting portion.

Since the porous metal plate has flexibility, the porous metal plate having flexibility is not broken even when it is wound in a spiral shape after being welded to the active material unfilled portion. Therefore, the porous metal plate of the electrode body and the substantially disk-shaped current collecting part are connected to each other without causing an internal short circuit in the electrode body, whereby a good current collecting performance can be obtained, and an alkaline storage battery capable of large current discharge can be obtained. Further, by using foamed nickel as an active material carrier having a three-dimensional mesh structure, since foamed nickel has flexibility, even if it is wound in a spiral shape, foamed nickel itself is not cut, and thus, an alkaline storage battery having excellent current collecting performance and a large capacity can be obtained without causing an internal short circuit in an electrode body.

Further, if a punched metal or a drawn metal mesh is used as the porous metal plate, the punched metal or the drawn metal mesh is flexible and does not break even when wound in a spiral shape. Further, if the cut portion is welded to the substantially disk-shaped current collecting portion, the cut portion is in convex contact with the substantially disk-shaped current collecting portion, and the current density of the portion in convex contact increases during resistance welding, so that the punched metal or the drawn metal mesh can be firmly fixed.

In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a cylindrical alkaline storage battery using a non-sintered electrode, which comprises a step of forming an unfilled portion in which an unfilled portion of an active material is formed in a longitudinal direction of one end portion of an active material carrier having a three-dimensional mesh structure constituting the non-sintered electrode, wherein the unfilled portion forming step is performed to form an unfilled portion in which the unfilled portion of the active material is formed in the longitudinal direction of the one end portion of the active material carrier having a three-dimensional mesh structure constituting the non-sintered electrode The method for manufacturing the electrode assembly includes a first welding step of welding a porous metal plate to an active material unfilled portion formed in the unfilled portion forming step in a longitudinal direction of one end portion of the active material carrier, an electrode body forming step of welding the porous metal plate in the first welding step with a separator interposed between a first electrode and a second electrode of the porous metal plate, and winding the porous metal plate in a spiral shape to form the electrode body, and a second welding step of welding the end portion of the porous metal plate welded to the first electrode and the second electrode of the electrode body wound in the spiral shape in the electrode body forming step and a substantially disk-shaped current collecting portion of the current collector.

Since it is impossible to weld the porous metal plate after filling the active material carrier with the paste-like active material, it is necessary to weld the porous metal plate after forming an active material unfilled portion in a portion of the collector which is connected to a substantially disk-shaped collector portion. Therefore, in the unfilled portion forming step, the porous metal plate is welded to the substantially disc-shaped current collecting portion after the active material unfilled portion is formed in the portion connected to the substantially disc-shaped current collecting portion, and then the end portion of the porous metal plate is welded to the substantially disc-shaped current collecting portion. Therefore, the porous metal plate and the active material carrier form a strong weld, and the current collecting performance can be improved.

Then, in the non-filled portion forming step, after the active material carrier is filled with the paste-like active material, if the paste-like active material filled in the portion to which the porous metal plate is to be welded is peeled off by ultrasonic vibration, the non-filled portion of the active material can be easily formed in the portion to which the porous metal plate is to be welded, so that the porous metal plate and the active material carrier are strongly welded, and the current collecting performance can be improved. In the unfilled portion forming step, the portion to which the porous metal plate is to be welded is shielded so that the paste-like active material is not filled in the welded portion before the paste-like active material is filled in the active material carrier, and the unfilled portion of the active material can be easily formed in the portion to which the porous metal plate is welded.

Further, if the method includes a first welding step of welding a porous metal plate in a longitudinal direction of one end of the active material carrier having a three-dimensional mesh structure constituting the non-sintered electrode, a paste filling step of filling a paste-like active material on the active material carrier to which the porous metal plate is welded in the first welding step to form the non-sintered electrode, an electrode body forming step of interposing a separator between one non-sintered electrode and the other electrode to which the paste-like active material is filled in the paste filling step and winding the electrode body in a spiral shape, and a second welding step of welding an end portion of the porous metal plate of the electrode body wound in a spiral shape in the electrode body forming step to a substantially circular plate-like current collecting portion, it is possible to easily form an active material non-filled portion in a portion connecting the substantially circular plate-like current collecting portion.

Further, if the cutting part is cut along the center part of the hole part of the punched metal or the drawn metal mesh, and the active material unfilled portion of the active material carrier is welded so that the cutting part comes into contact with the substantially disk-shaped current collecting part, and then the cutting part is welded to the substantially disk-shaped current collecting part of the current collector, the cutting part comes into contact with the substantially disk-shaped current collecting part in a projecting manner, and the current density of the portion in contact in the projecting manner is increased when resistance welding is performed, and thus, the cut part can be firmly fixed.

Description of the drawings:

the drawings are briefly described as follows.

Fig. 1 is a view showing a state in which a punching metal according to an embodiment of the present invention is welded to an active material unfilled portion of an active material carrier made of foamed nickel.

Fig. 2 is a view showing a state in which a metal tape in the conventional example is welded to an active material unfilled portion of an active material carrier made of foamed nickel.

Fig. 3 is a view showing a state in which a tongue-shaped current collecting tab of another conventional example is welded to an active material unfilled portion of an active material carrier made of foamed nickel.

Fig. 4 is a view showing a state in which an electrode assembly formed by winding the electrode of fig. 1 in a spiral shape is housed in a metal outer can to form a cylindrical nickel-metal hydride storage battery in a cross-sectional expanded state.

Fig. 5 is a perspective view showing the positive electrode current collecting plate.

Wherein, 10a, 10b, 10 c-nickel positive electrode; 10-foamed nickel (active material carrier with three-dimensional mesh structure); 11-an active substance; 12-active substance unfilled portion; 13. 14, 15-punched metal (porous metal plate); 40-negative electrode; 50-a membrane; 60-disc-shaped positive collector plate; 61-a current collecting part; 62-a lead-out section; 70-disc-shaped negative electrode collector plate; 80-cylindrical metal outer cans; 81-an opening; 90-sealing body; 91-positive electrode cover; 92-cover.

The specific implementation mode is as follows:

an embodiment in the case where a cylindrical alkaline storage battery using a non-sintered electrode according to the present invention is applied to a nickel-metal hydride storage battery will be described below with reference to the accompanying drawings.

Here, fig. 1 is a view showing a state where a porous metal plate of the present embodiment is welded to an active material unfilled portion of an active material carrier made of nickel foam, fig. 2 is a view showing a state where a metal plate (tape) of a comparative example (conventional example) is welded to an active material unfilled portion of an active material carrier made of nickel foam, fig. 3 is a view showing a state where a tongue-shaped current collecting tab of another comparative example (conventional example) is welded to an active material unfilled portion of an active material carrier made of nickel foam, fig. 4 is a view showing a state where an electrode body formed by winding the electrode of fig. 1 in a roll shape is housed in a metal outer can with its cross section expanded, and fig. 5 is a perspective view showing a positive electrode current collecting plate. 1. Production of nickel positive electrode plate a. example 1

90 parts by weight of nickel hydroxide, 5 parts by weight of metallic cobalt powder and 5 parts by weight of cobalt hydroxide powder were mixed, and the mixture was kneaded with 20 parts by weight of an aqueous solution containing 1% by weight of cellulose methyl ether to prepare an active material in the form of a paste. The active material 11 thus prepared in the form of a paste was filled to a level of 600g/m by weight per unit area of nickel²(in addition, the weight of nickel per unit area is 400 to 700g/m²) And a nickel foam (nickel sponge) having a thickness of 1.5mm in the active material carrier 10. The paste-like active material is filled so that the active material after rolling has a filling density of about 2.9 to 3.05 g/cc-void. Then, the active material carrier 10 filled with the paste-like active material 11 was dried and then rolled to a thickness of about 0.7 mm.

Then, the upper edge portion 12 of the active material carrier 10 filled with the paste-like active material 11 is aligned with an ultrasonic horn not shown in the drawing, and ultrasonic vibration is applied to the upper edge portion 12 in the vertical direction, so that the active material 11 filled in the upper edge portion 12 of the active material carrier 10 is detached from the active material carrier 10 to form a detached portion. At this time, ultrasonic vibration is given by aligning the ultrasonic horn, so that the upper edge portion 12 is compressed to form a thin-walled portion.

On the other hand, as shown in FIG. 1, as the porous metal plate, a nickel metal strip punched metal 13 is used, which has a thickness of 0.06mm, a plurality of circular holes with a diameter of 0.30 to 1.00mm formed in a staggered manner in each row, and a porosity of 20 to 60%. The nickel metal strip-like punched metal 13 was cut at the center of the circular hole, and the width thereof was 1.5 mm.

Then, the nickel metal strip-like punched metal 13 was placed on the peeled portion of the active material carrier 10, and resistance welding was performed at intervals of 2mm using a copper electrode having a diameter of 1.5mm, with a cut portion cut at the center of the circular hole slightly protruding from the upper end portion of the active material carrier 10, to obtain a nickel positive electrode plate 10a of example 1. Thus, at the upper end of the active material carrier 10, a part of the cut portion of the punching metal 13 protrudes a little more than the active material carrier 10. b. Example 2

After an active material 11 in a paste form prepared in the same manner as in example 1 was filled in an active material carrier 10 similar to example 1, the upper edge portion 12 of the active material carrier 10 was aligned with an ultrasonic horn not shown in the drawing, and ultrasonic vibration was applied to the upper edge portion 12 in the vertical direction, so that the active material 11 filled in the upper edge portion 12 of the active material carrier 10 was detached from the active material carrier 10 to form a detached portion. At this time, ultrasonic vibration is given by aligning the ultrasonic horn, so that the upper edge portion 12 is compressed to form a thin portion.

On the other hand, as shown in FIG. 1, as the porous metal plate, a nickel metal strip-shaped punched metal 14 is used, which has a thickness of 0.10mm, a plurality of circular holes with a diameter of 0.30 to 1.00mm formed in a staggered manner in each row, and a porosity of 20 to 60%. The nickel metal strip punched metal 14 was cut at the center of the circular hole, and its width was 1.5 mm.

Then, the nickel metal strip-like punched metal 14 was placed on the peeled portion of the active material carrier 10, and resistance welding was performed at intervals of 2mm using a copper electrode having a diameter of 1.5mm, with a cut portion cut at the center of the circular hole slightly protruding from the upper end portion of the active material carrier 10, to obtain a nickel positive electrode plate 10b of example 2. Thus, at the upper end portion of the active material carrier 10, a part of the cut portion of the punching metal 14 protrudes a little more than the active material carrier 10. c. Example 3

After an active material 11 in a paste form prepared in the same manner as in example 1 was filled in an active material carrier 10 similar to example 1, the upper edge portion 12 of the active material carrier 10 was aligned with an ultrasonic horn not shown in the drawing, and ultrasonic vibration was applied to the upper edge portion 12 in the vertical direction, so that the active material 11 filled in the upper edge portion 12 of the active material carrier 10 was detached from the active material carrier 10 to form a detached portion. At this time, ultrasonic vibration is given by aligning the ultrasonic horn, so that the upper edge portion 12 is compressed to form a thin portion.

On the other hand, as shown in FIG. 1, as the porous metal plate, a nickel metal strip-shaped punched metal 15 is used, which has a thickness of 0.18mm, a plurality of circular holes with a diameter of 0.30 to 1.00mm formed in a staggered manner in each row, and a porosity of 20 to 60%. The nickel metal strip punching metal 15 was cut at the center of the circular hole, and the width thereof was 1.5 mm.

Then, the nickel metal strip-like punched metal 15 was placed on the peeled portion of the active material carrier 10, and the cut portion cut at the center of the circular hole was slightly protruded from the upper end portion of the active material carrier 10, and resistance welding was performed with a copper electrode having a diameter of 1.5mm at intervals of 2mm, thereby producing a nickel positive electrode plate 10c of example 3. Thus, at the upper end portion of the active material carrier 10, a part of the cut portion of the punching metal 15 protrudes a little more than the active material carrier 10. d. Comparative example 1

As shown in fig. 2, after an active material 21 in a paste form prepared in the same manner as in example 1 was filled in an active material carrier 20 as in example 1, an upper edge portion 22 of the active material carrier 20 was aligned with an ultrasonic horn not shown in the drawing, and ultrasonic vibration was applied to the upper edge portion 22 in a vertical direction, so that the active material 21 filled in the upper edge portion 22 of the active material carrier 20 was detached from the active material carrier 20 to form a detached portion. At this time, ultrasonic vibration is given by aligning the ultrasonic horn, and the upper edge portion 22 is compressed to form a thin portion.

On the other hand, as shown in fig. 2, a nickel metal strip 23 (strip metal) having a thickness of 0.10mm and a width of 1.5mm was used as the metal plate, and the nickel metal strip 23 was placed on the peeled portion of the active material carrier 20, and resistance welding was performed with a copper electrode having a diameter of 1.5mm at intervals of 2mm to obtain a nickel positive electrode plate 20a of comparative example 1. e. Comparative example 2

As shown in fig. 3, after an active material carrier 30 similar to that of example 1 was filled with a paste-like active material 31 prepared in the same manner as in example 1, ultrasonic vibration was applied to the central upper portion of the active material carrier 30 while aligning a portion 32 of the central upper portion thereof with an ultrasonic horn having the same width, and the active material 31 filled in the portion 32 of the central upper portion of the active material carrier 30 was detached from the active material carrier 20 to form a detached portion. At this time, ultrasonic vibration is given by aligning the ultrasonic horn, and a portion 32 of the central upper portion is compressed to form a thin portion. A current collecting tab 33 comprising a nickel metal tongue-shaped piece having a width of 3.0mm and a thickness of 0.10mm was placed on the peeled portion, and resistance welding was performed using a copper welding rod having a diameter of 3.0mm to obtain a nickel positive electrode plate 30a of comparative example 2. 2. Production of Nickel-Metal hydride storage Battery A. Nickel-Metal hydride storage batteries of examples 1 to 3

Next, an example of manufacturing the nickel-metal hydride storage battery of each of the nickel positive electrode plates 10a, 10b, and 10c of the examples manufactured by the above-described method will be described with reference to fig. 4 (fig. 4 shows a case where the nickel positive electrode plate 10a is used) and fig. 5.

Separators 50 made of polypropylene nonwoven fabric were interposed between the nickel positive electrode plates 10a, 10b, and 10c produced by the above-described method and the negative electrode plate 40 having the hydrogen absorbing alloy coated on the punched metal 41, respectively, and the negative electrode plate 40 was wound in a spiral shape to produce a spiral electrode body a.

On the other hand, the positive electrode collector plate 60 is made of nickel metal, and as shown in fig. 5, the positive electrode collector plate 60 includes a substantially disk-shaped collector portion 61 and a lead-out portion 62, the substantially disk-shaped collector portion 61 has a large number of openings 63, and a groove 64 disposed to separate a pair of welding electrodes at the time of welding is provided in the center line of the collector portion 61 and extends to the lead-out portion 62. An electrolyte injection hole 65 is provided at the center of the substantially disk-shaped current collecting portion 61. The negative electrode current collector plate 70 is formed of a disk made of nickel metal.

Then, the end 41 of the negative electrode plate 40 of the spiral electrode assembly a produced as described above and the negative electrode current collecting plate 70 are resistance-welded, and the end of the strip-shaped punched metal 13 of the nickel positive electrode plates 10a, 10b, and 10c and the current collecting portion 61 of the positive electrode current collecting plate 60 are resistance-welded. In resistance welding, first, a pair of welding electrodes (not shown) facing each other are disposed in the groove 64 provided in the current collecting portion 61, and a welding current is flowed between the pair of welding electrodes to perform resistance welding.

Here, if a welding current flows between the pair of welding electrodes, a part of the cut portion of the strip-shaped punched metal 13 protrudes slightly from the active material carrier 10 at the upper end portion of the active material carrier 10 to form a protruding shape, and the welding current is concentrated at the portion where the protruding shape is formed, thereby fixing a part of the protruding portion to the peripheral wall of the hole 63. In this way, the strip-shaped punched metal 13 and the substantially disk-shaped current collecting portion 61 of the positive current collecting plate 60 are strongly fixed to each other.

Then, a cylindrical metal outer can 80 having a bottom of SC size is prepared, the spiral electrode body a having the collector plates 60 and 70 welded thereto as described above is inserted into the metal outer can 80, one welding electrode is inserted through the electrolyte injection hole 65 of the collector plate 60 and is connected to the negative collector plate 70, the bottom of the metal outer can 80 is connected to the other welding electrode, and the negative collector plate 70 and the bottom of the metal outer can 80 are spot-welded.

On the other hand, sealing body 90 including positive electrode lid 91 and lid 92 is prepared, leading portion 62 of positive electrode current collecting plate 60 and the bottom portion of lid 92 are brought into contact, and the bottom portion of lid 92 and leading portion 62 are welded. Then, an electrolyte solution composed of a 30 wt% aqueous solution of potassium hydroxide (KOH) was injected into each of the metal exterior cans 80, and the opening 81 of the exterior can 80 was crimped and sealed at the side of the opening 90 while the opening 90 was placed on the opening 81 through a sealing gasket 82. Thus, cylindrical nickel-metal hydride storage batteries of examples 1 to 3 having a nominal capacity of 2700mAH were produced. b. Nickel-metal hydride storage battery of comparative example 1

Next, examples of nickel-metal hydride storage batteries manufactured using the nickel positive electrode plates 20a and 30a of the comparative examples manufactured by the above-described methods will be described. First, a case of using the nickel positive electrode plate 20a of comparative example 1 will be described, and similarly to the above, the separator 50 made of polypropylene nonwoven fabric is interposed between the nickel positive electrode plate 20a and the negative electrode plate 40 formed by applying the hydrogen absorbing alloy to the punched metal 41, and the negative electrode plate 40 is wound in a spiral shape with the negative electrode plate 40 being outermost, thereby forming a spiral electrode body a.

On the other hand, a positive electrode collector plate 60 and a negative electrode collector plate 70 similar to those of the above-described embodiments are prepared, and the end 41 of the negative electrode plate 40 of the rolled electrode body a and the negative electrode collector plate 70 are resistance-welded, and the end of the strip-shaped metal 23 of the nickel positive electrode plate 20 and the substantially disk-shaped collector portion 61 of the positive electrode collector plate 60 are resistance-welded. At this time, since the welding current flows uniformly into the end portion of the strip-shaped metal 23, the strip-shaped metal 23 and the substantially disk-shaped current collecting portion 61 are not strongly fixed to each other.

Then, the bottom of the bottomed cylindrical metal outer can 80 having the same SC size as in the above example was spot-welded to the negative electrode current collecting plate 70, and then the bottom of the lid 92 of the sealing body 90 was welded to the lead-out portion 62 of the positive electrode current collecting plate 60. Then, an electrolyte solution composed of a 30 wt% aqueous solution of potassium hydroxide (KOH) was injected into the metal can 80, and the opening 81 of the can 80 was crimped and sealed at the side of the opening 90 while the opening 90 was placed on the opening 81 through a sealing gasket 82. Thus, a cylindrical nickel-metal hydride storage battery of comparative example 1 having a nominal capacity of 2700mAH was produced. c. Nickel-metal hydride storage battery of comparative example 2

Next, a case of using the nickel positive electrode plate 30a will be described, and similarly to the above, the separator 50 made of a polypropylene nonwoven fabric is interposed between the nickel positive electrode plate 30a and the negative electrode plate 40 formed by applying the hydrogen absorbing alloy to the punching metal 41, and the negative electrode plate 40 is wound in a spiral shape to form a spiral electrode body a.

Then, after the bottom of the bottomed cylindrical metal can 80 having the same SC size as in the above-described example and the end 41 of the negative electrode plate 40 of the spiral electrode body a are welded, the end of the tongue-shaped current collecting tab 33 of the nickel positive electrode plate 30a and the bottom of the lid 92 of the sealing body 90 are welded. Then, an electrolyte solution composed of a 30 wt% aqueous solution of potassium hydroxide (KOH) was injected into the metal can 80, and the opening 81 of the can 80 was crimped and sealed at the side of the opening 90 while the opening 90 was placed on the opening 81 through a sealing gasket 82. Thus, a cylindrical nickel-metal hydride storage battery of comparative example 2 having a nominal capacity of 2700mAH was produced. 3. Experimental results a. fraction defective

The fraction defective (the ratio of the number of nickel-metal hydride storage batteries in which an internal short circuit occurred) from the start of winding to the time of battery formation was measured for each of the cylindrical nickel-metal hydride storage batteries manufactured as described above, and the results shown in table 1 were obtained.

TABLE 1

Kind of polar plate	Example 1	Example 2	Example 3	Comparative example 1
					Percent defective (%)	0.5	1.0	1.6	2.4

Table 1 shows that, when the nickel positive electrode plate 10b of example 2 using the strip-shaped punched metal 14 having a thickness of 0.10mm and the nickel positive electrode plate 20a of comparative example 1 using the strip-shaped metal 23 having the same thickness of 0.10mm and having no hole were compared, the failure rate of the nickel positive electrode plate 10b of example 2 was halved as compared with the failure rate of the nickel positive electrode plate 20a of comparative example 1. This is because the use of the strip-shaped punched metal 14 increases the flexibility of the nickel positive electrode plate 10b, and prevents the occurrence of peeling of the welded portion when wound in a spiral shape.

Even if the nickel positive electrode plate 10c of example 3, which is 0.18mm thick, is used, the failure rate is lower than that of the nickel positive electrode plate 20a of comparative example 1, which is thinner than that. As described above, in the present invention, since the strip-shaped punched metals 13, 14, and 15 are welded to the active material carrier 10, the defective fraction is lower than that when the strip-shaped metal 23 having no hole is used.

In the above embodiments, the description has been given of the case of the strip-shaped punched metal provided with the circular hole, but the hole may be any shape other than the circular shape, such as a triangular shape, a quadrangular shape, or a pentagonal shape, so long as the same effect can be obtained. Also, the same effect can be obtained even if a drawn metal mesh is used instead of the punched metal. b. Battery capacity and operating voltage

Next, the discharge characteristics of each of the nickel-metal hydride storage batteries manufactured as described above were measured. In the measurement, the discharge capacity was measured by measuring the discharge time from the time when each nickel-metal hydride storage battery was charged to 100% and then discharged at a current of 10A until the battery voltage became 1.0V. The results obtained by performing the battery capacity test are shown in table 2. After each of the nickel-metal hydride storage batteries was charged at 100%, the battery was discharged at a current of 10A, and its operating voltage (average voltage value from the open state to the time when the load was discharged to 1.00V) was measured, and the results are shown in table 2.

TABLE 2

Kind of polar plate	Battery capacity (mAH)	Operating voltage (V)
			Example 1	2300	1.13
Example 2	2500	1.14
			Example 3	2600	1.15
Comparative example 1	2500	1.14
			Comparative example 2	200	1.03

Table 2 shows that if the nickel-metal hydride batteries using the nickel positive electrode plates 10a, 10b, 10c of examples 1, 2, and 3 are compared, respectively, the battery capacity and operating voltage can be improved as the thickness of the strip-shaped punched metal increases with the thickness of the punched metal 13 → the punched metal 14 → the punched metal 15. This is considered to be caused by an increase in voltage drop across the strip-shaped punched metal as the thickness of the punched metal 15 → the punched metal 14 → the punched metal 13 becomes thinner when the large current discharge of 10A is employed.

In the nickel-metal hydride storage battery of comparative example 2, the discharge capacity was extremely low and the operating voltage was also low. This is considered to be caused by an excessive voltage drop at the collector tab 34 when discharging with a large current of 10A if only the tongue-shaped piece collector tab 34 is provided.

Although the battery capacity and operating voltage of the nickel-hydrogen storage battery using the nickel positive electrode plate 10b (using the strip-shaped punched metal 14 having a thickness of 0.10 mm) of example 2 and the nickel-hydrogen storage battery using the nickel positive electrode plate 20a (using the strip-shaped metal 23 having a thickness of 0.10mm and no hole) of comparative example 1 are equal to each other, if the thickness of the strip-shaped metal 23 having no hole is increased to a value greater than the above thickness, the nickel positive electrode plate 20a loses its flexibility, and therefore, the thickness cannot be increased to a value greater than the above thickness. On the other hand, the nickel positive electrode plate 10b using the strip-shaped punched metal 14 is flexible, and the thickness of the strip-shaped punched metal can be increased.

As described above, in the present embodiment, since the strip-shaped punched metals 13, 14, 15 have flexibility, the strip-shaped punched metals 13, 14, 15 having such flexibility are welded to the active material unfilled portion 12, and then the strip-shaped punched metals 13, 14, 15 are not broken even when wound in a spiral shape. Therefore, the strip-shaped punched metals 13, 14, 15 of the electrode body A are connected to the positive current collecting plate 60 without causing an internal short circuit in the electrode body A, so that the alkaline storage battery has excellent current collecting performance, can improve the battery capacity and the operating voltage, and can perform large-current discharge.

In the above embodiment, as a method of forming the active material unfilled portion, the case of peeling off the active material by ultrasonic vibration was described as an example, but the present invention is not limited to this method, and the same effect can be obtained by masking the soldered portion of the punching metal with a resin tape or the like in advance, filling the active material, removing the mask, and then soldering the punching metal. The same effect can be obtained by welding the foamed nickel and the punching metal before filling the active material, and then filling the active material again.

Claims (9)

1. A cylindrical alkaline storage battery using a non-sintered electrode, wherein an electrode body formed by winding a paste-like active material on an active material carrier having a three-dimensional mesh structure made of foamed nickel with a separator interposed between one non-sintered electrode and the other electrode in a spiral shape is housed in a cylindrical metal outer can serving as the other electrode terminal, and an end portion of the non-sintered electrode is connected to a disc-shaped current collecting portion having a current collector connected to a lead-out portion of a sealing body for sealing an opening of the outer can,

the method is characterized in that an active material unfilled portion is formed along the longitudinal direction of one end of an active material carrier having a three-dimensional mesh structure constituting the non-sintered electrode, a porous metal plate is welded to the active material unfilled portion along the longitudinal direction of the one end of the active material carrier, and the end of the porous metal plate is welded to the disc-shaped current collecting portion.

2. The cylindrical alkaline storage battery using a non-sintered electrode as claimed in claim 1, wherein said porous metal plate is selected from a punched metal or a drawn metal mesh.

3. The cylindrical alkaline storage battery using a non-sintered electrode as claimed in claim 2, wherein said punched metal or expanded metal is cut along hole portions of said punched metal or expanded metal, and said cut portions are welded to the disc-shaped current collecting portion of said current collector.

4. A method of manufacturing a cylindrical alkaline storage battery using a non-sintered electrode according to claim 1, wherein the cylindrical alkaline storage battery using a non-sintered electrode is formed by filling a paste-like active material on an active material carrier having a three-dimensional mesh structure made of foamed nickel to form a one-electrode non-sintered electrode, then winding the electrode body in a spiral shape with a separator interposed between the non-sintered electrode and the other electrode, storing the electrode body in a cylindrical metal outer can serving also as the other electrode terminal, and connecting an end portion of the non-sintered electrode to the disc-shaped current collecting portion having a current collector connected to a lead-out portion of a sealing body sealing an opening of the outer can,

characterized by comprising an unfilled portion forming step of forming an unfilled portion of an active material in the longitudinal direction of one end of an active material carrier having a three-dimensional mesh structure constituting the non-sintered electrode, and a first welding step of welding a porous metal plate to the unfilled portion of the active material carrier formed in the unfilled portion forming step in the longitudinal direction of the one end of the active material carrier, an electrode body forming step of winding the porous metal plate in a spiral shape with a separator interposed between the one-electrode non-sintered electrode and the other-electrode to form an electrode body, which are welded in the first welding step, and a second welding step of welding an end portion of the porous metal plate welded to the one-electrode non-sintered electrode of the electrode body wound in a spiral shape in the electrode body forming step to a circular plate-shaped current collecting portion of the current collector.

5. The method of manufacturing a cylindrical alkaline storage battery using a non-sintered electrode as set forth in claim 4, wherein said unfilled portion forming step is a step of filling said active material carrier with a paste-like active material and then peeling off the paste-like active material filled in a portion to which said porous metal plate is to be welded by ultrasonic vibration.

6. The method of manufacturing a cylindrical alkaline storage battery using a non-sintered electrode as set forth in claim 4, wherein said unfilled portion forming step is a step of masking a portion to which said porous metal plate is to be welded so as not to fill the welded portion with the paste-like active material before the active material carrier is filled with the paste-like active material.

7. A method of manufacturing a cylindrical alkaline storage battery using a non-sintered electrode according to claim 1, wherein the cylindrical alkaline storage battery using a non-sintered electrode is formed by filling a paste-like active material on an active material carrier having a three-dimensional mesh structure made of foamed nickel to form a one-electrode non-sintered electrode, then winding the electrode body in a spiral shape with a separator interposed between the non-sintered electrode and the other electrode, storing the electrode body in a cylindrical metal outer can serving also as the other electrode terminal, and connecting an end portion of the non-sintered electrode to the disc-shaped current collecting portion having a current collector connected to a lead-out portion of a sealing body sealing an opening of the outer can,

the method is characterized by comprising a first welding step of welding a porous metal plate in the longitudinal direction of one end of the active material carrier having a three-dimensional mesh structure constituting the non-sintered electrode, a paste filling step of filling a paste-like active material on the active material carrier to which the porous metal plate is welded in the first welding step to form a one-electrode non-sintered electrode, an electrode body forming step of winding the one-electrode non-sintered electrode filled with the paste-like active material in the paste filling step and another electrode in a spiral shape with a separator interposed therebetween to form an electrode body, and a second welding step of welding the end of the porous metal plate welded to the one-electrode non-sintered electrode of the electrode body wound in a spiral shape in the electrode body forming step and a circular plate-shaped current collector of the current collector.

8. The method for manufacturing a cylindrical alkaline storage battery using a non-sintered electrode as claimed in claim 7, wherein said porous metal plate is selected from the group consisting of a punched metal and a drawn metal mesh.

9. The method of manufacturing a cylindrical alkaline storage battery using a non-sintered electrode as set forth in claim 8, wherein said punched metal or drawn metal mesh is cut along hole portions of said punched metal or drawn metal mesh, then an active material non-filled portion of said active material carrier is welded so that said cut portion is brought into contact with a disc-shaped current collecting portion of said current collector, and then said cut portion is welded to said disc-shaped current collecting portion of said current collector.