JP2012134107A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery capable of preventing residual electrolyte on an insulation plate when the electrolyte is injected.SOLUTION: A nickel-hydrogen secondary battery 2 comprises an outer can 10 whose upper end is opened; an electrode group 22, in which a positive electrode 24 and a negative electrode 26 are laminated via a separator 28, spirally wound and housed in the outer can 10; an upper insulation plate 32 arranged on a top of the electrode group 22 and having electric insulation; an electrolyte injected in the outer can 10 and impregnated in the electrode group 22; and a sealing body 14 fixed in the opening and sealing the opening by caulking an opening edge of the outer can 10. The upper insulation plate 32 has a liquid injection port 38 provided at its center and passing the electrolyte; an outer peripheral edge 42 having a size and a shape coincide with those of an inner peripheral edge of the outer can 10; and a funnel face 36 provided between the outer peripheral edge 42 and the liquid injection port 38 and indented toward a bottom wall 8 of the outer can 10.

Description

  The present invention relates to a battery including an insulating plate on an upper part of an electrode group in an outer can.

  In a general battery, an electrode group consisting of a positive electrode, a negative electrode, and a separator is accommodated in an outer can that also serves as a negative electrode terminal, and then an electrolyte is injected, and then the upper end opening of the outer can is sealed with a sealing body. It is manufactured by. The sealing body is disposed in the upper end opening of the outer can via an insulating packing, and these sealing body and packing are fixed to the opening edge of the outer can by caulking the opening edge of the outer can. Note that a positive electrode terminal, a safety valve, and the like are attached to the sealing body.

  In such a battery, the outermost negative electrode in the electrode group is in contact with the inner wall of the outer can, and the negative electrode and the outer can (negative electrode terminal) are electrically connected to each other. On the other hand, the positive electrode of the electrode group is electrically connected to the positive electrode terminal of the sealing body through a positive electrode lead made of a ribbon-like metal.

  By the way, when a vibration or impact is applied to the battery, a part of the positive electrode or the negative electrode of the electrode group may come into contact with the sealing body, the positive electrode lead, the outer can, etc. connected to the other electrode, thereby causing an internal short circuit. Therefore, an insulating plate is disposed above and below the electrode group to prevent the internal short circuit. In order to ensure the original electrical insulation, such an insulating plate generally has an outer peripheral shape that matches the inner peripheral shape of the outer can so as to completely cover the upper and lower ends of the electrode group. (See Patent Document 1).

Japanese Patent Laid-Open No. 06-243857

  By the way, the insulating plate arranged on the upper part of the electrode group has an electrolyte injection port in the center. In other words, when the battery is manufactured, the electrolytic solution injected from the upper end opening of the outer can reaches the electrode group in the outer can through the injection hole of the insulating plate, so that the electrode group is immersed in the electrolytic solution. The

  By the way, when injecting the electrolyte into the outer can, a part of the electrolyte adheres to the upper surface of the insulating plate, and this adhering electrolyte is particularly a boundary between the outer peripheral edge of the insulating plate and the inner peripheral surface of the outer can. It remains in the part.

  The electrolytic solution remaining in this way travels along the inner wall of the outer can along with vibrations and reaches the caulked portion of the sealing body.

In general, there is a possibility that the caulking portion of the battery may leave a minute gap inside due to distortion of the upper end opening of the outer can. For this reason, there exists a possibility that electrolyte solution may ooze out of the battery by the capillary phenomenon from the said clearance gap of a crimping part.
The exuded electrolytic solution may cause problems such as corrosion of other parts around the battery and a decrease in the capacity of the battery as the electrolytic solution in the battery decreases.

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a battery capable of preventing the electrolyte from remaining on the insulating plate when the electrolyte is injected. It is in.

  In order to achieve the above object, according to the present invention, an outer can whose upper end is opened, a positive electrode and a negative electrode are laminated via a separator, an electrode group accommodated in the outer can, and the electrode group An insulating plate having electrical insulation disposed at the top, an electrolyte injected into the outer can and impregnated in the electrode group, and an opening edge of the outer can is caulked to be fixed in the opening, A battery including a sealing body that seals the opening, wherein the insulating plate has a size and a shape that match a liquid injection port that is provided in the center and allows the electrolytic solution to pass therethrough and an inner peripheral edge of the outer can. And a funnel surface that is provided between the outer peripheral edge and the liquid inlet and that is recessed toward the bottom side of the outer can.

  Preferably, the outer peripheral edge of the insulating plate is configured such that a surface on the bottom side of the outer can is scraped obliquely and pointed toward an inner peripheral surface of the outer can.

  Moreover, it is preferable that the said exterior can is set as the structure which has comprised the cross-sectional shape circularly.

  Moreover, it is preferable that the said outer can is set as the structure which the cross-sectional shape has comprised the square shape.

  In the battery according to the present invention, the insulating plate disposed at the upper part of the electrode group has a funnel surface that is inclined toward the bottom side of the outer can toward the central liquid inlet, so that the electrolyte is injected into the liquid inlet. Are smoothly introduced to the electrode group side. For this reason, it is possible to prevent the electrolytic solution from remaining on the insulating plate, and to suppress the leakage of the electrolytic solution from the caulking portion of the battery.

  Further, in the battery according to the present invention, the outer peripheral edge of the insulating plate is sharpened toward the inner peripheral surface of the outer can because the bottom side surface of the outer can is sharply cut and sharpened toward the inner peripheral surface of the outer can. The contact with the inner peripheral surface of the outer can is a line contact. For this reason, even if the electrolyte exists at the boundary between the outer peripheral edge of the insulating plate and the inner peripheral surface of the outer can, the electrolyte is immediately guided to the liquid inlet along the funnel surface of the insulating plate. It can prevent more reliably that electrolyte solution remains in a boundary with a can.

  Furthermore, in the present invention, a circular insulating plate is used for a cylindrical battery having a circular outer cross-sectional shape, and a rectangular insulating plate is used for a rectangular battery having a rectangular outer cross-sectional shape. Therefore, the entire upper end portion of the electrode group can be covered, and the remaining of the electrolytic solution on the insulating plate can be prevented while maintaining a sufficient insulating effect.

It is the perspective view which fractured | ruptured and showed the cylindrical nickel-hydrogen secondary battery which concerns on this invention partially. It is the top view which showed the upper insulating board integrated in the nickel hydride secondary battery of FIG. It is sectional drawing which follows the III-III line in FIG. It is sectional drawing which showed typically the behavior of the electrolyte solution in the boundary part of the outer periphery of an upper insulating board, and the internal peripheral surface of an exterior can. It is the disassembled perspective view which fractured | ruptured and showed the square nickel-hydrogen secondary battery which concerns on this invention partially. FIG. 6 is a plan view showing an upper insulating plate incorporated in the nickel hydride secondary battery of FIG. 5. It is sectional drawing which follows the VII-VII line in FIG.

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

  As shown in FIG. 1, the battery 2 includes an outer can 10 having a bottomed cylindrical shape with an upper end opened. The outer can 10 has conductivity, and its bottom wall 8 functions as a negative electrode terminal. In the opening of the outer can 10, a conductive disc-shaped sealing body 14 and a ring-shaped insulating packing 12 surrounding the sealing body 14 are arranged, and 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 at 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 hermetically 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 strip-like positive electrode 24, a negative electrode 26, and a separator 28, and these 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. The outermost periphery of the electrode group 22 is formed by a part of the negative electrode 26 (the outermost periphery) and is in contact with the inner peripheral wall of the outer can 10. That is, the negative electrode 26 and the outer can 10 are electrically connected to each other.

  In the outer can 10, a positive electrode lead 30 is disposed between one end of the electrode group 22 and the sealing body 14, and both ends of the positive electrode lead 30 are connected to the inner end of the positive electrode 24 and the sealing body 14, respectively. . Accordingly, the positive electrode terminal 20 and the positive electrode 24 of the sealing body 14 are electrically connected to each other via the positive electrode lead 30 and the sealing body 14.

  An upper insulating plate 32 is disposed between the electrode group 22 and the sealing body 14. As apparent from FIG. 2, the upper insulating plate 32 has a circular shape in plan view, and a circular liquid injection port 38 through which an electrolytic solution can be inserted is provided at the center. A slit 40 through which the positive electrode lead 30 passes is provided at a predetermined position of the upper insulating plate 32. As the material of the upper insulating plate 32, a synthetic resin having electrical insulation properties, for example, polypropylene, polyethylene, polyvinyl chloride, or the like can be used. The upper insulating plate 32 preferably has a thickness of 0.15 mm to 0.3 mm in order to ensure a certain level of strength.

  More specifically, the upper insulating plate 32 has an outer diameter dimension substantially the same as the inner diameter dimension of the outer can 10 so that the outer peripheral edge 42 matches the inner peripheral surface of the cylindrical outer can 10. As is apparent from FIG. 3, the upper insulating plate 32 is a truncated portion protruding from the outer peripheral edge 42 toward the liquid injection port 38, that is, toward the bottom wall 8 side of the outer can 10 (in the direction of arrow A in FIG. 3). The surface opposite to the bottom wall 8 has a conical shape and is formed as a female tapered funnel surface 36 that reaches the liquid injection port 38. The funnel surface 36 is provided to smoothly guide the electrolytic solution to the liquid inlet 38 when the electrolytic solution is injected into the outer can 10. The inclination angle α of the funnel surface 36 with respect to the cross section of the outer can 10 is preferably set in the range of 3 degrees to 10 degrees. If the inclination angle α is smaller than 3 degrees, it is difficult to smoothly guide the electrolytic solution on the funnel surface 36 to the liquid inlet 38, and the electrolytic solution tends to remain on the upper insulating plate 32. Therefore, the inclination angle α is preferably 3 degrees or more, and more preferably 5 degrees or more. On the other hand, if the inclination angle α exceeds 10 degrees, the volume of the space occupied by the upper insulating plate 32 in the outer can 10 increases, and the volume of the electrode group 22 decreases accordingly, so that a desired battery capacity is secured. It is difficult to do.

  Further, as apparent from the enlarged view shown in the circle P of FIG. 3, the outer peripheral edge 42 of the upper insulating plate 32 is formed by shaving the surface on the bottom wall 8 side of the outer can 10, that is, its lower surface 44. As a result, it has a sharp shape. According to such an outer peripheral edge 42, as shown in FIG. 4, the contact between the outer peripheral edge 42 and the inner peripheral surface 6 of the outer can 10 is a line contact, and the boundary between the outer peripheral edge 42 and the inner peripheral surface 6 is electrolyzed. Even if the liquid L is present, the electrolyte L immediately flows smoothly down to the liquid injection port 38 along the funnel surface 36 of the upper insulating plate 32 and reaches the electrode group 22 through the liquid injection port 38. Therefore, the electrolytic solution L does not remain at the boundary, and therefore does not ooze out from the caulking portion.

  In the battery 2, as shown in FIG. 1, a lower insulating plate 34 is disposed between the electrode group 22 and the bottom wall 8 of the outer can 10. The lower insulating plate 34 has a flat circular shape. As the material of the lower insulating plate 34, as with the upper insulating plate 32, polypropylene, polyethylene, polyvinyl chloride, or the like can be used. Moreover, it is preferable to use the thickness of 0.15 mm to 0.3 mm.

  Furthermore, a predetermined amount of alkaline electrolyte (not shown) injected through the liquid injection port 38 of the upper insulating plate 32 exists in the outer can 10. The alkaline electrolyte is impregnated in the positive electrode 24, the negative electrode 26, and the separator 28, and the charge / discharge reaction between the positive electrode 24 and the negative electrode 26 proceeds. The type of the alkaline electrolyte is not particularly limited, and examples thereof include an aqueous sodium hydroxide solution, an aqueous lithium hydroxide solution, an aqueous potassium hydroxide solution, and an aqueous solution obtained by mixing two or more of these, Further, the concentration of the alkaline electrolyte is not particularly limited, and for example, a concentration of 8N (normality) can be used.

(Second Embodiment)
As a battery according to the second embodiment to which the present invention is applied, for example, a case where the present invention is applied to a prismatic nickel-hydrogen secondary battery 4 (hereinafter referred to as battery 4) shown in FIG. 5 will be described as an example.
The battery 4 of the second embodiment is characterized by the upper insulating plate 52 disposed on the upper part of the electrode group 50 as in the battery 2 of the first embodiment. This is the same as the prismatic battery having a general structure. Therefore, the description of the constituent members other than the upper insulating plate 52 is simplified.

  First, as shown in FIG. 5, the battery 4 includes an outer can 54 having a bottomed rectangular tube shape with an open upper end. The outer can 54 accommodates an electrode group 50 which is folded in a state where the separator 60 is sandwiched between the positive electrode 56 and the negative electrode 58 and is formed into a square shape as a whole. The negative electrode 58 is positioned at the outermost part of the electrode group 50 and is in contact with the inner peripheral wall of the outer can 54, whereby the negative electrode 58 and the outer can 54 are electrically connected to each other. On the other hand, a part of the positive electrode 56 of the electrode group 54 and the positive electrode terminal 64 of the sealing body 62 are electrically connected to each other via the positive electrode lead 64. A rectangular upper insulating plate 52 is disposed between the sealing body 62 and the electrode group 50.

In the opening of the outer can 54, a sealing body 62 and a rectangular ring-shaped insulating packing 66 surrounding the sealing body 62 are disposed. The sealing body 62 and the insulating packing 66 caulk the opening edge of the outer can 54. As a result, it is fixed to the opening edge of the outer can 54.
As shown in FIG. 6, the upper insulating plate 52 has a square shape in plan view, and includes a circular liquid inlet 70 through which an electrolytic solution can be inserted at the center. A slit 72 through which the positive electrode lead 64 passes is provided at a predetermined position of the upper insulating plate 52. As the material of the upper insulating plate 52, the same material as that of the first embodiment can be used, and the thickness of the upper insulating plate 52 is preferably set to the same thickness as that of the first embodiment.

  The upper insulating plate 52 has a size that matches the cross-sectional shape inside the rectangular outer can 54, and its outer peripheral edge 74 also has a rectangular shape. That is, the vertical and horizontal dimensions of the upper insulating plate 52 in plan view are set to be the same as the vertical and horizontal dimensions of the cross section inside the outer can 54. As apparent from FIG. 7, the upper insulating plate 52 is a truncated pyramid that protrudes from the outer peripheral edge 74 toward the liquid injection port 70, that is, toward the bottom wall of the outer can 54 (in the direction of arrow B in FIG. 7). The surface opposite to the bottom wall side is formed as an inclined pyramid-shaped funnel surface 68 that reaches the liquid injection port 70. The funnel surface 68 is provided to smoothly guide the electrolyte to the liquid inlet 70 when the electrolyte is poured into the outer can 54. The inclination angle α of the funnel surface 68 with respect to the transverse cross section of the outer can 54 is preferably set in the range of 5 to 10 degrees for the same reason as in the first embodiment. Here, as is apparent from FIG. 6, the funnel surface 68 includes a pair of triangular regions arranged across the liquid injection port 70, that is, obtuse isosceles triangular regions T <b> 1 and T <b> 2, and these regions T <b> 1 and T <b> 1. It comprises sharp isosceles triangular regions T3 and T4 sandwiched between T2.

Further, as is clear from the enlarged view shown in the circle Q of FIG. 7, the outer peripheral edge 74 of the upper insulating plate 52 is also cut off obliquely as in the first embodiment. It has a pointed shape and exhibits the same function as the first embodiment.
As the material of the upper insulating plate 52, polypropylene, polyethylene, polyvinyl chloride, or the like can be used as in the upper insulating plate 32 of the first embodiment. Moreover, it is preferable to use the thickness of 0.15 mm to 0.3 mm.

1. Example 1 Assembling of AA Size Cylindrical Nickel Metal Hydride Secondary Battery
A positive electrode 24 and a negative electrode 26 used for a general nickel metal hydride secondary battery were wound in a spiral shape with a separator 28 made of a nonwoven fabric made of polypropylene fiber sandwiched between them to produce an electrode group 22.

  Next, a bottomed cylindrical outer can 10 for AA size was prepared, a disk-shaped lower insulating plate 34 made of polypropylene was inserted into the outer can 10, and the above-described electrode group 22 was accommodated thereon. . Further, an upper insulating plate 32 made of polypropylene was placed on the electrode group 22.

  Here, the upper insulating plate 32 has a shape shown in FIGS. That is, the upper insulating plate 32 has a circular shape in which the plan view of the outer peripheral edge 42 matches the inner peripheral surface of the cylindrical outer can 10, and the outer diameter of the outer peripheral edge 42 The inner diameter of the can 10 is set to be the same. In addition, a liquid injection port 38 having a diameter of 1.5 mm is provided at the center. Further, the upper insulating plate 32 has a funnel surface 36 from the outer peripheral edge 42 toward the liquid injection port 38. The inclination angle α of the funnel surface 36 with respect to the transverse cross section of the outer can 10 is set to 10 degrees. Note that the thickness of the lower insulating plate and the upper insulating plate 32 was 0.3 mm.

  Thereafter, an alkaline electrolyte composed of an aqueous sodium hydroxide solution was poured into a 2 ml outer can. Thereafter, the sealing body 14 and the like were disposed in the opening of the outer can 10 and the opening edge of the outer can 10 was crimped to seal the opening, thereby assembling an AA size cylindrical nickel-hydrogen secondary battery. This nickel metal hydride secondary battery is referred to as battery A. In addition, 10,000 batteries A were assembled.

Example 2
A nickel-metal hydride secondary battery (battery B) similar to battery A of Example 1 was assembled except that the inclination angle α of the funnel surface of the upper insulating plate was 5 degrees.

Example 3
A nickel metal hydride secondary battery (battery C) similar to the battery A of Example 1 was assembled except that the inclination angle α of the funnel surface in the upper insulating plate was 4 degrees.
Example 4
A nickel metal hydride secondary battery (battery D) similar to battery A of Example 1 was assembled except that the inclination angle α of the funnel surface of the upper insulating plate was 3 degrees.

Comparative Example 1
A nickel hydride secondary battery (battery E) similar to the battery A of Example 1 was assembled except that the inclination angle α of the funnel surface of the upper insulating plate was 0 degree, that is, a flat upper insulating plate was used.

2. Rate of occurrence of liquid leakage of nickel metal hydride secondary battery After vibration was applied to batteries A to E for 6 hours, the caulking part was visually observed and the caulking part 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.

3. Evaluation results Table 1 clearly shows the following.
(1) Examples 1 to 4 (batteries A to D) having an upper insulating plate having a funnel surface inclined from the outer peripheral edge toward the central liquid injection port and a flat upper insulating plate not inclined When compared with Comparative Example 1 (battery E) having the above, it can be seen that Examples 1 to 4 have a lower rate of liquid leakage than Comparative Example 1. This is because in the batteries of Examples 1 to 4, when the electrolyte was injected, the electrolyte was quickly guided to the liquid injection port by the action of the funnel surface, so that the electrolyte remained on the upper insulating plate. It is difficult, and the electrolyte solution that has reached the electrode group quickly penetrates into the electrode group, and therefore hardly returns to the upper insulating plate. For this reason, it is considered that leakage of the electrolyte from the caulking portion is effectively prevented.

On the other hand, in the battery E of Comparative Example 1 including the flat upper insulating plate, there is a relatively large amount of electrolytic solution that does not reach the injection port when the electrolytic solution is injected, and the electrolytic solution is electrolyzed on the upper insulating plate. It is considered that a part of the liquid remains. For this reason, it is considered that the electrolyte remaining on the upper insulating plate oozes out from the minute gaps in the caulking portion to generate a battery that has leaked.
From this, it can be seen that providing the funnel surface on the upper insulating plate is effective in preventing leakage of the electrolyte.

(2) When Examples 1-4 (battery AD) provided with the upper insulating board which has a funnel surface are compared mutually, it turns out that a liquid leak incidence rate is so low that the inclination-angle of a funnel surface is large. This is presumably because the larger the tilt angle, the quicker the electrolyte is introduced to the injection port, so that the remaining electrolyte on the upper insulating plate can be suppressed as much as possible.

(3) Here, in particular, Example 1 and Example 2 (Battery A and Battery B) have a very low liquid leakage occurrence rate. That is, when the inclination angle of the funnel surface exceeds 5 degrees, the liquid leakage occurrence rate is 0%. For this reason, the inclination angle of the funnel surface of the upper insulating plate is preferably 5 degrees or more.

2 Nickel Metal Hydride Battery 10 Exterior Can 12 Insulating Packing 14 Sealing Body 20 Positive Terminal 24 Positive Electrode 26 Negative Electrode 32 Upper Insulating Plate 36 Funnel Surface 38 Injection Port 40 Slit

Claims (4)

An outer can with an open top;
A positive electrode and a negative electrode are laminated via a separator, and an electrode group accommodated in the outer can,
An insulating plate having electrical insulation disposed on the electrode group;
An electrolyte solution injected into the outer can and impregnated in the electrode group;
A battery provided with a sealing body that is fixed in the opening by caulking the opening edge of the outer can, and sealing the opening;
The insulating plate is
A liquid injection port provided in the center for passing the electrolyte solution;
An outer peripheral edge having a size and shape matching the inner peripheral edge of the outer can;
A battery including a funnel surface provided between the outer peripheral edge and the liquid injection port and recessed toward the bottom side of the outer can. The outer peripheral edge of the insulating plate is
2. The battery according to claim 1, wherein a surface on a bottom side of the outer can is sharply cut and sharpened toward an inner peripheral surface of the outer can.   The battery according to claim 1, wherein the outer can has a circular cross-sectional shape.   The battery according to claim 1, wherein the outer can has a square cross-sectional shape.

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