JP2013012349A - Alkaline storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline storage battery which can prevent electrolyte leakage.SOLUTION: In an alkaline storage battery 2 comprising an electrode group 22 composed of cathodes 24 and anodes 26 wound in spiral form via separators 28 interposed in between and a cathode collector plate 38 connected to the cathodes 24, the electrode group 22 and the cathode collector 38 are accommodated along with an electrolyte in a bottomed cylindrical outer can 10 having an open top, and the opening of the outer can 10 is sealed with a sealing body 14 connected to the cathode collector 38. The alkaline storage battery 2 includes a spiral gap 58 formed between the cathodes 24 and the anodes 26 by burying the top edge on the sealing body 14 side of a separator 28 in the axial direction of the electrode group 22 from an upper end 54 formed with the anodes 26 of the electrode group 22, and belt-like adhesive tapes 50 disposed in spiral form throughout the gap 58. The adhesive tapes 50 have electrical insulation properties and impermeability against the electrolyte, and are disposed in a row in the axial direction of the electrode group 22 with respect to the separators 28.

Description

  The present invention relates to an alkaline storage battery.

  Alkaline storage batteries such as nickel metal hydride secondary batteries are widely used as power sources for mobile phones, power tools, electric vehicles and the like.

  Here, in particular, in batteries used for electric tools, electric vehicles, and the like, it is desired to improve the high-rate discharge characteristics together with the further increase in capacity and output. As a battery excellent in such a high rate discharge characteristic, for example, the battery of Patent Document 1 is known.

  In a battery excellent in high rate discharge characteristics represented by Patent Document 1, a positive electrode and a positive electrode terminal of an electrode group are electrically connected via a positive electrode current collector. Specifically, in the electrode group in which the positive electrode and the negative electrode are spirally wound via a separator, the upper end edge of the positive electrode protrudes spirally from the upper end of the electrode group, and the protruding upper end The entire edge is joined to the positive electrode current collector. Thereby, since a positive electrode connects with a positive electrode electrical power collector in a wide range, the internal resistance of a battery becomes small and a high rate discharge characteristic improves.

  Here, in the battery described above, the upper end portion of the separator protrudes relatively long from the upper end of the negative electrode of the electrode group, and is arranged along the upper end edge of the positive electrode. Thereby, since the upper end edge of the positive electrode protruding from the electrode group is covered with the separator, an internal short circuit is prevented from occurring.

JP 2000-21435 A

  By the way, in the above-described battery, oxygen gas is generated from the positive electrode when charged more than the battery capacity (hereinafter referred to as overcharge). On the other hand, when discharging more than the battery capacity (hereinafter referred to as reverse charging), hydrogen gas is generated from the positive electrode. These gases pass through the separator and escape to the upper part of the electrode group. At this time, the electrolyte in the separator is pushed upward. As a result, a phenomenon of electrolyte rising through the separator occurs. Here, as described above, since the upper end portion of the separator protrudes toward the upper end side of the electrode group, the electrolytic solution scooped up in the separator flows out from the upper end portion of the separator and accumulates on the upper portion of the electrode group. As described above, when the internal pressure of the battery is increased and the safety valve is opened in a state where the electrolytic solution is accumulated in the upper part of the electrode group, the electrolytic solution leaks out of the battery together with the gas. When the liquid leakage occurs in this way, the leaked electrolytic solution corrodes other parts around the battery, or causes a problem that the capacity of the battery is reduced as the electrolytic solution in the battery decreases.

  This invention is made | formed based on said situation, The place made into the objective is to provide the alkaline storage battery which can prevent the leakage of electrolyte solution.

  In order to achieve the above object, according to the present invention, an electrode group in which a positive electrode and a negative electrode are spirally wound with a separator interposed therebetween, and a positive electrode assembly electrically connected to the positive electrode. The electrode group and the positive electrode current collector are housed together with an alkaline electrolyte in a bottomed cylindrical outer can having an open top, and the opening of the outer can is electrically connected to the positive electrode current collector. In the alkaline storage battery formed by sealing with a connected sealing body, the upper end edge of the separator on the sealing body side is buried in the axial direction of the electrode group from the upper end formed by the negative electrode of the electrode group, and the positive electrode and A spiral gap formed between the negative electrodes, and a strip-shaped plug member disposed in a spiral shape over the entire gap, the plug member being electrically insulative and non-conductive to the electrolyte. Permeability Has, alkaline storage battery, characterized in that it is arranged in the axial direction with respect to the separator is provided (claim 1).

  In addition, the positive electrode includes an upper edge that protrudes from the upper end of the electrode group toward the sealing body and is connected to the positive electrode current collector, and the plug member has an upper portion at the upper edge of the positive electrode. It is preferable that the electrode group protrudes from the upper end of the electrode group.

  Preferably, the plug member is a pressure-sensitive adhesive tape made of an insulating resin, and the pressure-sensitive adhesive tape is bonded to a surface of the positive electrode facing the gap and a side surface of the upper edge. 3).

  Moreover, it is preferable that the said adhesive tape has the same thickness as the thickness of the said separator, and it is set as the structure by which the said adhesive tape and the said separator are faced | matched mutually (Claim 4).

  In the alkaline storage battery according to the present invention, the upper end edge on the sealing body side of the separator is positioned at the position buried in the axial direction of the electrode group from the upper end of the electrode group, thereby forming a spiral gap formed between the positive electrode and the negative electrode. And a strip-shaped plug member fitted over the entire gap, and the plug member has electrical insulation and impermeability to the electrolyte solution. The electrolytic solution that has been scooped up in the separator is scooped up by this plug member and is blocked. Thereby, it can prevent that electrolyte solution leaks and accumulates in the upper part of an electrode group. As a result, it is possible to effectively prevent the electrolyte from leaking out of the battery.

  Further, since the upper portion of the plug member protrudes from the upper end of the electrode group along the upper end edge of the positive electrode, the upper end edge of the positive electrode can be covered, which contributes to prevention of internal short circuit.

  In addition, by using an insulating resin adhesive tape for the plug member, the plug member can be easily provided on the sealing member side of the separator, which contributes to the improvement of the manufacturing efficiency of the battery with less liquid leakage.

  Further, the pressure-sensitive adhesive tape has the same thickness as the separator, and the pressure-sensitive adhesive tape and the separator are abutted against each other, so that the electrolyte rises at the upper edge of the separator. Can be blocked. Moreover, it can suppress that the contact surface with respect to the said negative electrode of an adhesive tape and a separator becomes mutually flush, and the part of an adhesive tape becomes thick locally. Thereby, it is possible to prevent the winding deviation from occurring when the electrode group is wound.

It is the front view which fractured | ruptured and showed the cylindrical nickel-hydrogen secondary battery which concerns on this invention partially. It is the perspective view which showed typically the state which expand | deployed the positive electrode integrated in the nickel-hydrogen secondary battery of FIG. FIG. 2 is a cross-sectional view schematically showing a connection region between a positive electrode and a positive electrode current collector plate in the nickel hydride secondary battery of FIG. 1.

Hereinafter, an alkaline storage battery according to the present invention will be described with reference to the drawings.
As an alkaline storage battery according to an embodiment to which the present invention is applied, for example, a case where the present invention is applied to an AA size cylindrical nickel-hydrogen secondary battery (hereinafter referred to as a battery) 2 shown in FIG. 1 will be described as an example.

  As shown in FIG. 1, the battery 2 includes an outer can 10 having a bottomed cylindrical shape with an open upper end. The outer can 10 has conductivity, and the bottom wall 8 functions as a negative electrode terminal. In the opening of the outer can 10, a disc-shaped sealing body 14 having conductivity and a ring-shaped insulating packing 12 surrounding the sealing body 14 are arranged. The insulating packing 12 and the sealing body 14 are opened in the outer can 10. The edge is fixed to the opening edge of the outer can 10 by caulking. That is, the sealing body 14 and the insulating packing 12 cooperate with each other to seal the opening of the outer can 10.

  Specifically, the sealing body 14 has a gas vent hole 16 in the center, and a rubber valve body 18 that closes the gas vent hole 16 is disposed on the outer surface of the seal body 14. Further, a flanged cylindrical positive terminal 20 is fixed on the outer surface of the sealing body 14 so as to cover the valve body 18, and the positive terminal 20 presses the valve body 18 toward the sealing body 14. Therefore, the gas vent hole 16 is normally airtightly closed by the valve body 18. On the other hand, when gas is generated in the outer can 10 and its internal pressure increases, the valve body 18 is compressed by the internal pressure and opens the gas vent hole 16. As a result, the gas vent hole 16 and the positive electrode terminal 20 are opened from the outer can 10. Gas is released via That is, the vent hole 16, the valve body 18, and the positive electrode terminal 20 form a safety valve for the battery.

  An electrode group 22 is accommodated in the outer can 10. Each of the electrode groups 22 includes a belt-like positive electrode 24, a negative electrode 26, and a separator 28, which are wound in a spiral shape with the separator 28 sandwiched between the positive electrode 24 and the negative electrode 26. That is, the positive electrode 24 and the negative electrode 26 are overlapped with each other via the separator 28.

  A predetermined amount of an alkaline electrolyte (not shown) is injected into the outer can 10, and a charge / discharge reaction occurs between the positive electrode 24 and the negative electrode 26 via the alkaline electrolyte contained in the separator 28. proceed.

  Further, in the outer can 10, a circular metal negative electrode current collector plate 30 is disposed between the bottom wall 8 and the electrode group 22, and the negative electrode 26 is disposed via the negative electrode current collector plate 30. The outer can 10 is electrically connected. More specifically, the negative electrode 26 includes a negative electrode substrate 32 made of, for example, punching metal, and a negative electrode active material layer 34 containing a hydrogen storage alloy is held on both surfaces of the negative electrode substrate 32. The negative electrode substrate 32 protrudes from the negative electrode active material layer 34 toward the negative electrode current collector plate 30, and the protruding portion is welded to the negative electrode current collector plate 30.

  Further, in the outer can 10, a circular metal positive electrode current collector plate 38 is also disposed between the electrode group 22 and the lid plate 14. A strip-shaped lead portion 40 is integrally formed on the positive electrode current collector plate 38, and the leading end of the lead portion 40 is welded to the lid plate 14, and the lid plate 14, the positive electrode current collector plate 38, and the lead portion 40 are interposed therebetween. The positive electrode 24 is electrically connected to the positive electrode terminal 20.

  More specifically, the positive electrode 24 is a non-sintered electrode and has a conductive positive electrode substrate 42 having a strip shape as shown in FIG. The positive electrode substrate 42 is made of a metal porous body and includes innumerable holes formed by a skeleton having a three-dimensional network structure. The pores of the positive electrode substrate 42 are filled with nickel hydroxide particles as a positive electrode active material, except for the upper edge 43 positioned on the sealing body 14 side when viewed in the axial direction of the electrode group 22.

The upper end edge 43 of the positive electrode substrate 42 includes a thin region 44 and a metal thin plate 48 joined to the thin region 44.
Specifically, as shown in FIG. 2, the thin region 44 is a portion in which one surface (the upper surface in FIG. 2) is pressed in the thickness direction and crushed, and is filled with the positive electrode active material. It is thinner than the (main body part 46). And the strip | belt-shaped metal thin plate 48 is welded to this crushed part. As apparent from FIG. 2, the metal thin plate 48 has a length in the direction toward the sealing body 14 longer than a length in the direction toward the sealing body 14 in the thin area 44, and protrudes from the thin area 44. Further, the metal thin plate 48 matches the level difference between the thin region 44 and the main body 46 and is substantially flush with the main body 46. The metal thin plate 48 functions as a positive electrode tab.

  Adhesive tapes 50 and 50 are bonded to both surfaces of the positive electrode 24 near the edge on the sealing body 14 side. Specifically, these adhesive tapes 50, 50 extend over the entire area in the longitudinal direction (winding direction) of the positive electrode 24, and on one surface, the metal tape straddles the step portion between the thin region 44 and the main body 46. The thin plate 48 and the main body 46 are partially bonded to each other, and the other surface is bonded to a position facing one surface.

  The adhesive tapes 50 and 50 have mechanical strength that does not easily penetrate sharp objects such as metal protrusions, and further have electrical insulation and impermeability to an electrolytic solution. As the adhesive tapes 50, 50, for example, polypropylene and polyethylene adhesive tapes or heat welding tapes are used. An adhesive tape made of polyolefin resin such as polypropylene and polyethylene is excellent in alkali resistance and is suitable for an alkaline battery. The thicknesses of the adhesive tapes 50 and 50 are substantially the same as those of the separator 28. Specifically, the adhesive tapes 50 and 50 have a thickness of 50 to 200 μm, for example.

  The positive electrode 24 to which the adhesive tape 50 is bonded as described above is spirally wound together with the negative electrode 26 via the separator 28 to form the electrode group 22. At this time, the separator 28 is arranged and wound so as not to overlap the adhesive tape 50. Specifically, the separator 28 is positioned in the main body 46 of the positive electrode 24 at a position corresponding to the bottom wall side of the outer can relative to the adhesive tapes 50, 50, and the separator 28 and the adhesive tape 50 abut each other's edges. Arranged. Thereby, since the contact surface with respect to the negative electrode 26 of the separator 28 and the adhesive tape 50 makes a substantially flush surface, the part of the adhesive tape 50 does not become thick locally, and winding deviation does not occur at the time of winding.

  Next, FIG. 3 schematically shows an enlarged connection region between the positive electrode 24 and the positive electrode current collector plate 38 described above. In the electrode group 22, the positive electrode 24 is wound so that the metal thin plate 48 is inside the battery 2. And the adhesive tape 50 is each positioned in the radial direction inner side and radial direction outer side so that the positive electrode 24 may be pinched | interposed. Further, when viewed in the axial direction of the electrode group 22, the thin region 44 of the positive electrode 24, the metal thin plate 48, and the adhesive tape 50 protrude from the upper end of the electrode group 22, that is, the upper end 54 of the negative electrode 26. A positive electrode tab is welded to the positive electrode current collector plate 38.

  Here, as is apparent from FIG. 3, when viewed in the axial direction of the electrode group 22, the upper edge 56 of the separator 28 is buried in the electrode group 22, and the positive electrode 24 and the negative electrode 26 formed thereby are An adhesive tape 50 is present in the gap 58 therebetween. Since this adhesive tape 50 is impervious to the electrolytic solution, even if overcharging or reverse charging occurs and the electrolyte creeps up, the electrolytic solution is blocked by the adhesive tape 50 portion. The leakage of the electrolyte solution to the upper part of the electrode group 22 is suppressed. As a result, the electrolytic solution is effectively prevented from accumulating on the upper part of the electrode group 22, so that the electrolytic solution is prevented from leaking out of the battery 2 even if the safety valve is opened. In addition, since the adhesive tape 50 has high mechanical strength, the adhesive tape 50 can be torn even if it is in contact with a portion where a part of the skeleton of the positive electrode substrate 42 protrudes or an edge portion at the boundary between the thin region 44 and the main body 46. It also contributes to the prevention of internal short circuits.

  The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the type of battery is not limited to a nickel-hydrogen secondary battery, but a nickel-cadmium secondary battery, lithium ion A secondary battery or the like may be used.

1. Battery production (Example)
(1) Production of positive electrode After conducting a conductive treatment on a sponge-like organic porous body, which is an open-cell polyurethane foam, nickel plating was performed by dipping in a plating solution in an electrolytic cell. Next, the nickel-plated organic porous body is roasted at a temperature of 750 ° C. for a predetermined time to remove the resin component of the organic porous body, and further sintered in a reducing atmosphere to obtain a metallic porous body made of nickel. It was. The obtained metal porous body had a basis weight of about 600 g / m ² , a porosity of 95%, and a thickness of about 2.0 mm.

  On the other hand, 10 parts by weight of cobalt powder and 3 parts by weight of zinc oxide powder were added to 90 parts by weight of nickel hydroxide powder containing 2.5% by weight of zinc and 1% by weight of cobalt as a coprecipitation component. The whole was mixed, 50 parts by mass of an aqueous hydroxypropylcellulose solution (solid content: 0.2% by weight) was added to the mixture, and the whole was kneaded to obtain a paste-like positive electrode active material slurry.

The obtained positive electrode active material slurry was filled in a metal porous body. The filling amount was adjusted so that the active material density after rolling was about 2.91 g / cm ³ . After drying the active material slurry, the metal porous body was roll-rolled so as to have a thickness of about 0.7 mm. And the rolled metal porous body was cut | disconnected in strip shape, and the active material of the one side edge part of the obtained strip was removed by ultrasonic peeling. Then, the said side edge part was roll-rolled again from one surface side, and formed in the thin area | region whose thickness is 0.5 mm. This thin region has a step of 0.2 mm from one surface of the main body filled with the positive electrode active material.

  Thereafter, a nickel ribbon having a thickness of 0.2 mm and a width of 3 mm was connected to one surface of the thin region over the entire length of the thin region by electric resistance welding. Thereby, the nickel ribbon is connected in a state of being flush with the main body.

  Next, a positive electrode was formed by adhering an adhesive tape to both surfaces of the thin region and a range including a part of the main body. Here, as this pressure-sensitive adhesive tape, a polypropylene pressure-sensitive adhesive tape having high mechanical strength, electrical insulation and impermeability to an electrolytic solution was used. This adhesive tape has a thickness of 70 μm and a width of 3 mm. And this adhesive tape is located in the position which covers the boundary of a nickel ribbon and a main-body part on the one surface side of a positive electrode, and covers these nickel ribbons and a main-body part partially, and adhere | attaches over the whole area of the positive electrode in the longitudinal direction. Has been. Moreover, the adhesive tape was adhere | attached in the position facing the adhesive tape of the one surface side in the other surface side of a positive electrode.

(2) Battery assembly The positive electrode manufactured as described above and the negative electrode containing a hydrogen storage alloy were wound through a separator made of polypropylene nonwoven fabric to obtain a spiral electrode group. Here, the thickness of the separator was set to 70 μm, which is the same as the thickness of the adhesive tape. And this separator was arrange | positioned so that it might not overlap with an adhesive tape, and the winding operation | work was performed. Thereby, the adhesive tape and the separator were in a state of being arranged in a state where the edges of each other were abutted in the electrode group. That is, the upper end edge of the separator is positioned at a position buried in the axial direction of the electrode group from the upper end of the electrode group, thereby forming a spiral gap between the positive electrode and the negative electrode, and extending over the entire gap. The adhesive tape is in the fitted state. And the upper part of an adhesive tape protrudes from the upper end of an electrode group along the thin area | region and positive electrode tab of a positive electrode.

  Next, after welding the positive electrode current collector plate and the negative electrode current collector plate to both ends of the obtained electrode group, the electrode group was inserted into the outer can, and the negative electrode current collector plate was spot welded to the bottom wall of the outer can and the positive electrode The lead part of the current collector plate was welded to the sealing body. Thereafter, an electrolytic solution composed of a 7.5N potassium hydroxide aqueous solution containing lithium hydroxide and sodium hydroxide was poured into the outer can. And the opening edge was crimped in the state which has arrange | positioned the sealing body in the opening of the exterior can through the insulating packing, and the cylindrical nickel-hydrogen secondary battery with a nominal capacity of 1200 mAh was assembled. This nickel metal hydride secondary battery is referred to as battery A. In addition, 1000 pieces of this battery A were assembled.

(Comparative example)
A nickel-hydrogen secondary battery (battery) similar to battery A of the example except that the separator was placed so as to overlap with the adhesive tape and the winding work was performed, and the upper edge of the separator was protruded from the upper part of the electrode group B) was assembled.

2. Rate of occurrence of liquid leakage of nickel metal hydride secondary battery The batteries A and B were overcharged with a charging current of 3C for 60 minutes.

After overcharging, the vicinity of the sealing body of each battery was visually observed, and the vicinity of the sealing body was wiped with litmus paper. And when the liquid leak was confirmed visually or when the litmus paper changed from red to blue, it was determined that the liquid leaked, and the number of batteries leaked was counted. The number of leaked batteries is defined as the number of leaked batteries. And the liquid leak occurrence rate shown by (I) type | formula was calculated | required.
Liquid leak occurrence rate (%) = (number of liquid leaks / total number of assembled batteries) × 100 (I)
The obtained results are shown in Table 1.

5. Evaluation results Table 1 clearly shows the following.
Comparing battery A (example) and battery B (comparative example), it can be seen that battery A has a lower rate of electrolyte leakage than battery B. In the electrode group of battery A, the adhesive tape is positioned on the upper part of the separator, and the upper edge of the separator does not protrude from the upper surface of the electrode group. Therefore, even if the electrolyte crawls up in the separator due to overcharging, the adhesive tape The electrolyte solution is blocked by For this reason, since the electrolytic solution does not leak to the upper part of the electrode group, the electrolytic solution is effectively prevented from collecting on the upper part of the electrode group. Therefore, even if the safety valve is activated, the electrolyte does not leak out of the battery, and the liquid leakage occurrence rate is considered to be lower than that of the battery B.

  On the other hand, in the electrode group of battery B, the separator overlaps the adhesive tape, and the upper edge of the separator protrudes from the upper part of the electrode group. The electrolyte that has been scooped out flows out from the upper end of the separator and accumulates at the top of the electrode group. For this reason, when the internal pressure of the battery rises and the safety valve opens, the rate of liquid leakage is higher than that of battery A because the electrolyte that has accumulated on the top of the electrode group is released together with the gas released to the outside of the battery. It is thought that.

  From the above results, it is considered that the upper edge of the separator is positioned at a position where it is buried in the electrode group, and the adhesive tape having electrical insulation and impermeability to the electrolytic solution is disposed on the separator. It turns out that it is effective in preventing the leakage of the liquid.

2 Nickel-metal hydride secondary battery 10 Exterior can 12 Insulating packing 14 Sealing body 20 Positive electrode terminal 24 Positive electrode 26 Negative electrode 28 Separator 42 Positive electrode substrate 43 Upper edge portion 44 Thin region 48 Metal thin plate 50 Adhesive tape 56 Upper edge 58

Claims (4)

An electrode group in which a positive electrode and a negative electrode are spirally wound with a separator interposed therebetween, and a positive electrode current collector electrically connected to the positive electrode, the electrode group and the positive electrode current collector In an alkaline storage battery in which a bottomed cylindrical outer can with an upper end is accommodated together with an alkaline electrolyte, and the opening of the outer can is sealed with a sealing body electrically connected to the positive electrode current collector,
A spiral gap formed between the positive electrode and the negative electrode by burying the upper end edge of the separator on the sealing body side in the axial direction of the electrode group from the upper end formed by the negative electrode of the electrode group;
A strip-shaped plug member disposed in a spiral shape over the entire gap,
The plug member is
An alkaline storage battery having electrical insulation and impermeability to the electrolyte, and arranged side by side in the axial direction with respect to the separator. The positive electrode is
Projecting from the upper end of the electrode group to the sealing body side, and including an upper end edge connected to the positive electrode current collector,
The plug member is
2. The alkaline storage battery according to claim 1, wherein an upper portion thereof protrudes from an upper end of the electrode group along an upper end edge portion of the positive electrode. The plug member is
It is an adhesive tape made of insulating resin,
The adhesive tape is
3. The alkaline storage battery according to claim 1, wherein the alkaline storage battery is bonded across a surface of the positive electrode facing the gap and a side surface of the upper edge portion. The adhesive tape is
Having the same thickness as the separator,
The alkaline storage battery according to claim 3, wherein the adhesive tape and the separator are abutted against each other.

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