JP2010192193A - Sealed alkaline storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed alkaline storage battery superior in safety function by forming a cylindrical part in which the center part of a spiral electrode group does not form a blocked state. <P>SOLUTION: The conductive core body 11 used in a negative electrode 10 of the spiral electrode group is constituted of a porous steel plate, a double-sided coated part X on which both faces of the conductive core body 11 are coated with a negative electrode active material 12, and a one-sided coated part Y, on which its one face is coated with the negative electrode active material are formed. A winding part of the negative electrode 10 of the spiral electrode group is constituted of a double-sided exposed part X1, in which the negative electrode active material 12 of both faces of the conductive core body 11 is removed; both faces of the conductive core body 11 are exposed, and a one-sided exposed part X2, in which the negative electrode active material 12 of one face of the conductive core body 11 is removed and only one face of the conductive core body 11 is exposed; and in the first of the winding of the electrode 10 of the innermost circumference of the spiral electrode group, the tip part of the double-sided exposed part X1 is welded to one part of the one-sided exposed part X2 and is made into a cylindrical form. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sealed alkaline storage battery, and in particular, a separator comprising a hydrogen storage alloy negative electrode using a hydrogen storage alloy as a negative electrode active material and a positive electrode using nickel hydroxide as a main positive electrode active material, and isolating these two electrodes The present invention relates to a sealed alkaline storage battery in which a spiral electrode group wound in a spiral shape and an alkaline electrolyte are accommodated in an outer can.

  In recent years, with the rapid spread of portable electronic devices, sealed batteries used in these devices are required to be small, light and high in energy. Among these types of sealed batteries, secondary batteries capable of charging and discharging have become widespread. Here, in this type of sealed storage battery (secondary battery), a spiral electrode group is formed by winding a positive electrode and a negative electrode in a spiral manner with a separator interposed therebetween, and current collectors are welded to both end faces thereof. Alternatively, the negative electrode is brought into contact with the case, the lead welded to a part of the positive electrode is welded to the sealing plate, the electrolytic solution is injected, sealed, and sealed.

  By the way, in this type of sealed storage battery, overcharge due to abnormal charging due to a failure of the charger or the like occurs, or the temperature rise is caused by malfunction of the device or mistake of use procedure, etc. May be in an abnormal state. When such overcharge occurs or the inside of the battery is in an abnormal state, the positive electrode plate is expanded or the separator is melted, and the central portion of the spiral electrode group eventually becomes closed. When the central part of such a spiral electrode group is in a closed state, the safety function is deteriorated and the battery is cracked or, in the worst case, the battery is ruptured.

  Therefore, various measures have been proposed so that the central part of the spiral electrode group is not closed. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2002-75434) proposes a structure in which a large space is formed at the center of the spiral electrode group and a large amount of electrolyte can be held in this space. Has been. In Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-229177), a cylindrical center pin is provided in the inner space of the center of the spiral electrode group in order to obtain a sealed storage battery that is unlikely to cause abnormal heat generation due to an internal short circuit. An arrangement has been proposed in which a part of the end of the side wall of the center pin is not in contact with the spiral electrode group.

  Moreover, in patent document 3 (Unexamined-Japanese-Patent No. 2001-210385), the core by which the positive electrode active material mixture or the negative electrode active material mixture is not apply | coated to the positive electrode core body or the negative electrode core body in the inner end of a positive electrode or a negative electrode. A body region is formed, and this core region region has been proposed in which a cylindrical portion that forms a cylindrical center hole penetrating the battery body in the axial direction is formed in the central portion of the spiral electrode group.

JP 2002-75434 A JP 2003-229177 A Japanese Patent Laid-Open No. 2001-210385

However, as proposed in Patent Document 1, a large space is formed at the center of the spiral electrode group, and a structure that can hold a large amount of electrolyte in this space is filled in the battery. Since the amount of the active material to be reduced is reduced, a high-capacity sealed battery is not obtained, and the quality of this type of sealed battery is deteriorated.
Further, as proposed in Patent Document 2, when a cylindrical center pin is inserted into the inner space of the center portion of the spiral electrode group, the cost increases and an operation for inserting the center pin is performed. There was also a problem that it was complicated and could not be easily manufactured.

  Furthermore, as proposed in Patent Document 3, even if a cylindrical part that forms a cylindrical central hole is formed in the central part of the spiral electrode group by the core region, the cylindrical part is made of metal foil ( In the case of the positive electrode core body, it is made of an aluminum foil, and in the case of the negative electrode core body, it is formed of a copper foil). Therefore, the mechanical strength is weak, and the central portion of the spiral electrode group may be closed.

  Therefore, the present invention has been made to solve the above-described problems, and is formed with a cylindrical portion that prevents the central portion of the spiral electrode group from being closed, thereby providing a sealed alkali excellent in safety function. The object is to provide a storage battery.

  The sealed alkaline storage battery of the present invention includes a negative electrode using a hydrogen storage alloy as a negative electrode active material and a positive electrode using nickel hydroxide as a main positive electrode active material, and is wound in a spiral shape through a separator that separates both the electrodes. The rotated spiral electrode group and the alkaline electrolyte are accommodated in an outer can. And in order to achieve the said objective, while the conductive core used for the negative electrode of the spiral electrode group consists of a porous steel plate, the negative electrode active material was apply | coated to both surfaces of the said conductive core. And a single-side coated portion in which a negative electrode active material is coated on one side thereof, and the negative electrode winding start portion of the spiral electrode group is formed by removing the negative electrode active material on both sides of the conductive core body. A double-sided exposed portion where both sides of the body are exposed, and a single-sided exposed portion where only one side of the conductive core is exposed by removing the negative electrode active material on one side of the conductive core, and the innermost circumference of the spiral electrode group In the first turn of the negative electrode winding, the tip of the double-sided exposed portion is welded to a part of the single-sided exposed portion to form a cylindrical shape.

  Here, the conductive core is made of a porous steel plate, and the tip of the double-sided exposed portion as described above is welded to a part of the single-sided exposed portion to wind the innermost negative electrode of the spiral electrode group. If the tip of the double-sided exposed part is welded to a part of the single-sided exposed part to form a cylindrical shape, the first turn of the innermost negative electrode of this spiral electrode group The strength will be great. Thereby, the cylindrical innermost periphery formed in the central part of the spiral electrode group can be prevented from being closed, and a sealed alkaline storage battery excellent in safety function can be obtained. In this case, it is desirable that a part of the single-side exposed portion is a base portion of the single-side exposed portion, and it is desirable that the conductive core made of a porous steel plate is a steel plate punching metal.

  In the present invention, since the strength of the innermost circumference of the cylindrical shape formed in the central portion of the spiral electrode group is large, it is possible to prevent the central portion of the spiral electrode group from being closed. As a result, it is possible to provide a sealed alkaline storage battery having an excellent safety function.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the negative electrode which uses the hydrogen storage alloy used for the sealed alkaline storage battery of this invention as a negative electrode active material, FIG.1 (a) is a top view which shows the plane of a negative electrode typically, 1 (b) is a cross-sectional view schematically showing the AA ′ cross section of FIG. 1 (a), and FIG. 1 (c) is a part of the winding start side of FIG. It is sectional drawing which expands and shows typically the state by which the 1st round of the negative electrode of the center part of the spiral electrode group became substantially cylindrical shape. It is sectional drawing which shows typically the sealed alkaline storage battery of this invention.

  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. Hydrogen Storage Alloy Negative Electrode (1) Example As shown in FIG. 1, a negative electrode 10 using the hydrogen storage alloy of this example as a negative electrode active material is formed on the surface of a conductive core 11 made of a porous substrate (punching metal). A negative electrode mixture layer 12 containing a hydrogen storage alloy powder serving as a negative electrode active material is formed. In this case, the conductive core 11 is composed of a nickel-plated soft steel porous substrate (punching metal), and the punching metal opening ratio ([total area of the opening of the core / length of the core). × width] × 100) is used in which openings are formed so as to be 25 to 30%.

  The negative electrode mixture layer 12 is formed by applying a hydrogen storage alloy slurry containing a hydrogen storage alloy powder to the surface of the conductive core 11, and as shown in FIG. The double-sided application part X where the hydrogen storage alloy slurry is applied to both sides of the conductive core 11 and the single-sided application part Y where the hydrogen storage alloy slurry is applied only to one side of the conductive core 11. In addition, in the front-end | tip part (it becomes the winding start side at the time of setting it as a spiral electrode group) of the double-sided application part X, the double-sided peeling part X1 from which the double-sided negative mix layer 12 peeled, and the single-sided negative mix layer A single-side peeled portion X2 from which 12 is peeled is formed.

  In this embodiment, the length of the double-sided application part X is 100 mm, of which 2 mm from the tip is the double-sided peeling part X1, and 10 mm from the end of this double-sided peeling part X1 is the single-sided peeling part X2. Yes. Moreover, the length of the single-side application part Y is 43 mm.

Next, an example of the production of the hydrogen storage alloy negative electrode 10 of the above-described embodiment will be described below. First, a powder of a hydrogen storage alloy (in this case, for example, one represented by La _0.2 Nd _0.7 Mg _0.1 Ni _3.7 Al _0.1 ) and 0.1% by mass of CMC with respect to 100 parts by mass of the hydrogen storage alloy powder. A styrene butadiene latex (SBR) as a thermoplastic elastomer and ketjen black as a carbon-based conductive agent are added to a water-soluble binder composed of (carboxymethylcellulose) and water (or pure water). Thereafter, these are mixed and kneaded to prepare a hydrogen storage alloy slurry.

Next, a conductive core 11 made of a nickel-plated soft steel porous substrate (punching metal) is prepared, and a predetermined filling density (for example, 5.0 g / cm ³ ) is provided in the conductive core 11. The hydrogen storage alloy slurry is applied so as to become), dried, and then rolled to a predetermined thickness. In addition, it applies so that the above-mentioned double-side application part X and the single-side application part Y may be formed at the time of application | coating this slurry. Thereby, the negative electrode which consists of the double-sided application part X by which the hydrogen storage alloy slurry was apply | coated to both surfaces of the conductive core 11, and the single-sided application part Y by which the hydrogen storage alloy slurry was apply | coated to only one side of the conductive core 11 The mixture layer 12 is formed.

  After drying, rolling to a predetermined thickness, cutting to a predetermined dimension, and then a predetermined part from the leading edge of the double-side coated part X (in this case, a part 2 mm from the leading edge in the length direction) The double-sided peelable portion X1 is formed by peeling off the negative electrode mixture layer 12 on both sides up to a predetermined portion (in this case, 10 mm from the end of X1 in the length direction). The single-sided negative electrode mixture layer 12 is peeled up to a portion of the above-mentioned part to form a single-sided peeled portion X2, thereby producing the hydrogen storage alloy negative electrode 10 (a) of the example.

(2) Comparative Example On the other hand, in the hydrogen storage alloy negative electrode 10 (x) of the comparative example, the difference from the hydrogen storage alloy negative electrode 10 (a) of the above-described example is that the tip of the double-side coated part X (spiral shape) The double-sided peeling portion X1 from which the double-sided negative electrode mixture layer 12 has been peeled off and the single-sided peeling portion X2 from which the single-sided negative electrode mixture layer 12 has been peeled off are formed on the winding start side when forming an electrode group). Other than that, since it is the same as the hydrogen storage alloy negative electrode 10 (a) of the above-described embodiment, the description thereof will be omitted.

2. Nickel positive electrode The nickel positive electrode 20 is formed by filling a porous nickel sintered substrate with a positive electrode active material mainly composed of a predetermined amount of nickel hydroxide. Next, an example of manufacturing such a nickel positive electrode 20 will be described below. First, a porous nickel sintered substrate having a porosity of about 85% is immersed in a mixed aqueous solution of nickel nitrate and cobalt nitrate having a specific gravity of 1.75, and nickel salt and cobalt are placed in the pores of the porous nickel sintered substrate. Keep salt. Thereafter, the porous nickel sintered substrate is immersed in a 25% by mass sodium hydroxide (NaOH) aqueous solution to convert the nickel salt and the cobalt salt into nickel hydroxide and cobalt hydroxide, respectively.

Next, after sufficiently washing with water to remove the alkaline solution, drying is performed, and the active material mainly composed of nickel hydroxide is filled in the pores of the porous nickel sintered substrate. Such an active material filling operation is repeated a predetermined number of times (for example, 6 times) so that the filling density of the active material mainly composed of nickel hydroxide in the pores of the porous sintered substrate becomes 2.5 g / cm ^3. To fill. Then, after making it dry at room temperature, it cut | disconnects to a predetermined dimension and the nickel positive electrode 20 is produced. In the nickel positive electrode 20, a positive electrode lead 21 for welding to a sealing body 50 described later is welded to an appropriate location on the upper side of the nickel positive electrode 20.

3. Nickel-hydrogen storage battery Next, a nickel-hydrogen storage battery using the hydrogen storage alloy negative electrode 10 (a) of the example having the above-described configuration or the hydrogen storage alloy negative electrode 10 (x) of the comparative example and the nickel positive electrode 20 is used. An example of manufacturing will be described below. First, a hydrogen storage alloy negative electrode 10 (a, x) and a nickel positive electrode 20 are prepared, and a separator 30 made of a nonwoven fabric subjected to a sulfonation treatment is interposed between these electrodes 10 and 20 to form a laminate. After that, in the hydrogen storage alloy negative electrode 10 (a) of the example, the tip of the double-sided peeling portion X1 that becomes the winding start side when the spiral electrode group is formed is an approximately root (single-side peeling portion) of the single-sided peeling portion X2. After winding so that it may be located in the vicinity of the boundary part of X2 and the site | part in which the peeling part is not formed, these laminated bodies are wound and it is set as a spiral electrode group. In this case, the single-sided application portion Y of the hydrogen storage alloy negative electrode 10 (a, x) is located on the outermost periphery of the spiral electrode group obtained, and the conductive core 11 of the single-side application portion Y is exposed. .

  Thereafter, in the spiral electrode group produced using the hydrogen storage alloy negative electrode 10 (a) of the example, a small welding electrode rod was pressed against the center of the spiral electrode group, and the spiral electrode group A welding electrode as a counter electrode is pressed against the conductive core 11 exposed on the outermost periphery. Then, a predetermined welding voltage is applied to the pair of welding electrodes, and the conductive cores 11 in the vicinity of the front end portion of the double-sided peeling portion X1 and the substantially root portion of the single-sided peeling portion X2 are welded together. A welded portion 11 a is formed in the width direction of the body 11. Thereby, in the spiral electrode group produced using the hydrogen storage alloy negative electrode 10 (a) of the example, a substantially cylindrical tubular shape formed from the first innermost circumference of the central part of the spiral electrode group. The part Z will be formed. In addition, the spiral electrode group manufactured using the hydrogen storage alloy negative electrode 10 (x) of the comparative example does not include such a welding process.

  As described above, after the spiral electrode group is formed, the conductive cores 11 are welded to each other in the vicinity of the front end portion of the double-sided peeling portion X1 and the substantially root portion of the single-sided peeling portion X2. Instead of forming the welded portion 11a in the width direction, the welded portion 11a may be formed before forming the spiral electrode group.

  In this case, after winding the tip of the double-sided peeling portion X1 that is the winding start side so as to be positioned near the root of the single-sided peeling portion X2, a small welding electrode rod is pressed against the center portion. The welding electrode as a counter electrode is pressed against the conductive core 11 exposed on the outermost periphery of the spiral electrode group. Then, a predetermined welding voltage is applied to the pair of welding electrodes, and the conductive cores 11 in the vicinity of the front end portion of the double-sided peeling portion X1 and the substantially root portion of the single-sided peeling portion X2 are welded together. What is necessary is just to form the welding part 11a in the width direction of the body 11. FIG.

  Next, after the obtained spiral electrode group is housed in a bottomed cylindrical outer can 40 in which iron is nickel-plated (the outer surface of the bottom surface becomes a negative electrode external terminal), an appropriate location on the upper side of the nickel positive electrode 20 The positive electrode lead 21 welded to the sealing plate 51 is welded to the sealing plate 51 constituting the bottom of the sealing body 50 having the insulating gasket 44 attached to the outer periphery. The sealing body 50 is provided with a positive electrode cap 52 serving as a positive electrode terminal, and a valve body 53 and a spring 54 that are deformed when a predetermined pressure is reached in a space formed by the sealing plate 51 and the positive electrode cap 52. The pressure valve which consists of is arrange | positioned.

  Next, after forming the annular groove 41 on the outer periphery of the upper portion of the outer can 40, the electrolytic solution was injected, and the outer peripheral portion of the sealing body 50 was mounted on the annular groove 41 formed on the upper portion of the outer can 40. An insulating gasket 44 is placed. Then, the nickel-hydrogen storage battery is produced by caulking the opening edge 42 of the outer can 40. In this case, an alkaline electrolyte composed of a 30% by mass potassium hydroxide (KOH) aqueous solution is poured into the outer can 40 so as to be 2.5 g (2.5 g / Ah) per battery capacity (Ah), Nickel-hydrogen storage batteries A and X having a battery capacity of 2700 mAh were produced. In addition, what used the hydrogen storage alloy negative electrode 10 (a) of the Example was made into the nickel-hydrogen storage battery A, and what used the hydrogen storage alloy negative electrode 10 (x) of the comparative example was made into the nickel-hydrogen storage battery X.

4). Overcharge test Next, 20 nickel hydride storage batteries A and X were used, respectively, and the 7.5A overcharge test was performed to determine the number of ruptures of the outer can 40. The results shown in Table 1 below were obtained. It became. In this case, the 7.5A overcharge test was performed as follows. That is, the batteries A and X were placed horizontally, the batteries A and X were sandwiched between the positive and negative terminals, respectively, and 7.5 A constant current charging was performed until the batteries A and X were completely short-circuited.

  As is clear from the results in Table 1 above, in the nickel-hydrogen storage battery X manufactured using the hydrogen storage alloy negative electrode 10 (x) of the comparative example, the number of ruptured outer cans was 4, and the ratio was 20 % Is reached. On the other hand, in the nickel-hydrogen storage battery A manufactured using the hydrogen storage alloy negative electrode 10 (a) of the example, the number of ruptures of the outer can is 0, and the safety is extremely improved. I understand.

This is because, in the nickel-hydrogen storage battery X, the central part of the spiral electrode group is not firmly fixed, so that the inside of the battery X becomes abnormal due to overcharging, and the nickel positive electrode 20 expands and the separator 30 This is probably because the center of the spiral electrode group is closed due to melting or the battery X is ruptured.
On the other hand, in the nickel-hydrogen storage battery A, since the substantially cylindrical tubular portion Z is formed and firmly fixed at the center of the spiral electrode group, the inside of the battery A becomes abnormal due to overcharging. Even if the nickel positive electrode 20 is expanded or the separator 30 is melted, the central portion of the spiral electrode group is not closed, so that it is considered that the battery A does not rupture.

  In the above-described embodiment, an example in which the sealed alkaline storage battery of the present invention is applied to a nickel-hydrogen storage battery has been described. However, the sealed alkaline storage battery of the present invention is not limited to a nickel-hydrogen storage battery, but a nickel-cadmium storage battery. Of course, the present invention can be applied to other sealed alkaline storage batteries.

DESCRIPTION OF SYMBOLS 10 ... Hydrogen storage alloy negative electrode, 11 ... Electroconductive core for negative electrodes, 12 ... Active material layer, X ... Double-sided coating part, X1 ... Double-sided peeling part, X2 ... Single-sided peeling part, Y ... Single-sided coating part, Z ... Substantially cylindrical Cylindrical portion, 20 ... nickel positive electrode, 21 ... positive electrode lead, 30 ... separator, 40 ... outer can, 41 ... annular groove, 42 ... opening edge, 43 ... insulating gasket, 50 ... sealing body, 51 ... sealing Plate 52 ... Positive electrode cap 53 ... Valve plate 54 ... Spring

Claims (3)

A spiral electrode group comprising a negative electrode having a hydrogen storage alloy as a negative electrode active material and a positive electrode having nickel hydroxide as a main positive electrode active material, and spirally wound through a separator separating these two electrodes; A sealed alkaline storage battery that contains an alkaline electrolyte in an outer can,
The conductive core used for the negative electrode of the spiral electrode group is made of a porous steel plate, and a double-sided coating portion in which the negative electrode active material is applied to both surfaces of the conductive core, and a negative electrode active on one side thereof. A single-sided application part coated with a substance is formed,
The winding start portion of the negative electrode of the spiral electrode group includes a double-sided exposed portion in which the negative electrode active material on both surfaces of the conductive core body is removed and both surfaces of the conductive core body are exposed, and the conductive core body The negative electrode active material on one side is removed and a single-side exposed portion where only one side of the conductive core is exposed,
In the first round of winding of the negative electrode at the innermost circumference of the spiral electrode group, the tip of the double-sided exposed part is welded to a part of the single-sided exposed part to form a cylindrical shape. Sealed alkaline storage battery.   2. The sealed alkaline storage battery according to claim 1, wherein a part of the one-side exposed portion is a base portion of the one-side exposed portion.   The sealed alkaline storage battery according to claim 1, wherein the porous steel plate is a punching metal made of a steel plate.

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