JP2007242395A - Alkaline storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkaline storage battery suitable for large-current application, capable of sufficiently ensuring vibration resistance/impact resistance, and having a simple structure. <P>SOLUTION: This alkaline storage battery is structured such that an electrode group composed by rolling a sheet-like positive electrode body and a sheet-like negative electrode body by interposing a separator therebetween is stored in a bottomed cylindrical armoring body 5 through a collector 7 welded to the negative electrode body; the negative electrode body is connected to the armoring body; a sealing body 6 connected to a collector lead 8 having a bent part exhibiting an elastic action and welded to the positive electrode body is insulated from the armoring body, and arranged in an opening of the armoring body. A member wherein an elastic coefficient C (=B/A) expressed by a crushing load B [N] and a crushing amount A [mm] of the collector lead is not smaller than 90.00 [N/mm] is used particularly for the collector lead 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an alkaline storage battery having a structure in which an electrode group in which a sheet-like positive electrode body and a negative electrode body are wound via a separator is housed in an exterior body, and the opening is covered with a sealing body.

  A cylindrical storage battery (secondary battery) such as a nickel metal hydride battery is formed by winding a sheet-like positive electrode body 1 and a negative electrode body 2 with separators 3 and 3 interposed therebetween as shown in FIG. The electrode group 4 thus prepared is housed in a bottomed cylindrical exterior body 5 and the electrode group 4 is immersed in an electrolytic solution, and then insulated from the exterior body 5 and the opening of the exterior body 5 is sealed with a sealing body 6. It has a sealed structure. At both ends of the electrode group 4, disc-shaped current collectors 7 are respectively provided by welding to tab portions led out from the positive electrode body 1 and the negative electrode body 2. Then, for example, the negative electrode side current collector 7 connected to the negative electrode body 2 is welded to the can bottom of the outer package body 5 so that the outer package body 5 functions as a negative electrode. The current collector 7 is connected to the sealing body 6 through a current collecting lead 8 as shown in Patent Document 1, for example, so that the sealing body 6 functions as a positive electrode.

For the negative electrode side current collector 7 provided at the bottom of the can of the outer package 5, for example, as shown in FIG. 2, a substantially U-shaped groove 7a is provided at the center thereof to provide an elastic action in the plate thickness direction. The tongue piece 7b having the shape is formed, and the tongue piece 7b is welded to the bottom of the can of the outer package 5. The tongue piece 7b has a function of absorbing vibration applied to the electrode group 4 and suppressing breakage due to stress concentration on the welded portion.
JP 2002-231216 A

  However, when the current collector 7 having the above-described tongue piece 7b is used, it cannot be denied that the battery resistance is increased due to current inhibition caused by the U-shaped groove 7a. Specifically, in an alkaline storage battery used for a large current application such as a hybrid vehicle or an electric vehicle, the increase in battery resistance described above becomes a big problem. However, when the current collector 7 not provided with the tongue piece 7b is used, there is a problem that stress concentration occurs due to vibrations on the welded portion, which tends to cause disconnection. For this reason, it is strongly desired to realize an alkaline storage battery having a structure that is used for large currents and that also ensures vibration resistance and impact resistance.

  The present invention has been made in view of such circumstances, and its purpose is suitable for large current applications, and has a simple structure capable of sufficiently ensuring vibration resistance and impact resistance. Is to provide.

The alkaline storage battery according to the present invention to achieve the above-described object is
<a> an electrode group in which a sheet-like positive electrode body and a negative electrode body are wound via a separator;
<b> A current collector welded to the one electrode body led to one end of the electrode group and integrated with the electrode group;
<c> A bottomed cylindrical exterior body that houses the electrode group and is electrically connected to the current collector;
<d> a bending lead having an elastic action, and a current collecting lead attached to the electrode group by welding to the other electrode body led to the other end of the electrode group;
<e> a sealing body that is electrically connected to the current collecting lead and insulated from the exterior body so as to cover the opening of the exterior body,
<f> In particular, the current collecting lead has an elastic coefficient C (= B / A) indicated by a crushing load B [N] and a crushing amount A [mm] of the current collecting lead of about 97.7 [N / mm]. ] It is characterized by using the above.

  Preferably, the current collecting lead is crushed between opposing portions of a conductor piece or a substantially cylindrical conductor ring bent in a substantially U shape, and has an elastic force having the elastic modulus C described above in the crushing direction. It consists of something that has

  According to the alkaline storage battery having the above configuration, the electrode group housed in the exterior body is pressed with a current collecting lead having an elastic coefficient of about 90.00 [N / mm] or more and sealed with a sealing body. Therefore, the vibration applied to the alkaline storage battery can be effectively absorbed by the current collecting lead. As a result, it is possible to effectively prevent the current collector and the exterior body from being welded without using a current collector provided with a tongue piece, and it is not necessary to provide a tongue piece on the current collector. Therefore, the problem of increase in battery resistance due to the U-shaped groove described above can be solved.

  In other words, according to the present invention, since it is possible to suppress the increase in resistance of the current collector, it is suitable for large current applications, and it is effectively absorbed by the current collecting lead and its vibration resistance and impact resistance are improved. It is possible to realize an alkaline storage battery having a simple structure that can be sufficiently secured and prevented from being detached.

Hereinafter, an alkaline storage battery according to an embodiment of the present invention will be described with reference to the drawings, taking a nickel-metal hydride storage battery as an example.
This nickel metal hydride storage battery basically has a structure as shown in FIG. The sheet-like positive electrode body 1 is formed by forming a nickel sintered porous body on the surface of an electrode plate core made of, for example, a punching metal, and then, using a chemical impregnation method, an active mainly composed of nickel hydroxide in the nickel sintered porous body. It consists of a material filled. Further, the sheet-like negative electrode body 2 is formed, for example, by filling the surface of an electrode plate core made of punching metal with a paste-like negative electrode active material made of a hydrogen storage alloy.

Such a positive electrode body 1 and a negative electrode body 2 are spirally formed at a winding pressure of 0.4 MPa by interposing two separators 3 and 3 each having a basis weight of 70 g / m ^{2 made} of, for example, a polypropylene nonwoven fabric. The spiral electrode group 4 having a substantially cylindrical shape with a diameter of 30 mm and a length of 50 mm is manufactured. Note that an end portion of a punching metal that is an electrode plate core body of the positive electrode body (nickel positive electrode plate) 1 is provided on the upper end surface of the spiral electrode group 4 so as to protrude as a tab portion. An end portion of a punching metal that is an electrode plate core body of the negative electrode body (hydrogen storage alloy plate) 2 is provided as a tab portion so as to protrude from the lower end surface of the negative electrode body.

On the other hand, as shown in FIG. 3, a substantially disk-shaped current collector 7 having a large number of apertures is prepared, and these current collectors 7 are positively projecting from both ends of the spiral electrode group 4 described above. It welds to the tab part of the electrode body (nickel positive electrode plate) 1 and the negative electrode body (hydrogen storage alloy plate) 2. Incidentally, the current collectors 7 and 7 are made of a nickel-plated steel plate having a diameter of approximately 29 mm and a thickness of 0.2 mm, for example. For comparison, a current collector 7 having a tongue piece 7a formed at the center thereof was also prepared as shown in FIG. 2 described above.

  Then, the spiral electrode group 4 in which the pair of current collectors 7 and 7 are welded to both ends thereof, specifically, the current collector 7 on the negative electrode side as shown in FIG. The outer casing 5 is housed in a bottomed cylindrical outer casing (outer can) 5 so as to be opposed to the above, and the current collector 7 is welded to the bottom of the can to make the outer casing 5 a negative electrode of a nickel metal hydride storage battery. The outer package 5 is for a so-called cylindrical battery having a can diameter of 31 mm and a can length of 60 mm, for example. Further, the current collector 7 on the positive electrode side positioned on the opening side of the outer package 5 has a current collecting lead 8 having a bent portion and exhibiting an elastic action, specifically, a conductor bent in a substantially U shape. One end of the current collecting lead 8 made of a conductor ring having a piece or a substantially oval cross section is welded.

  Thereafter, the outer package (outer can) 5 is filled with an alkaline electrolyte composed of, for example, 7N (normal) potassium hydroxide and 1N (normal) lithium hydroxide, and the spiral electrode group 4 is immersed therein. As shown in FIG. 5 (b) above, the sealing body 6 is placed in the opening of the exterior body 5 via an insulating ring (not shown). Then, after welding the sealing body 6 to the other end of the current collecting lead 8, a predetermined load is applied from above the sealing body 6 to crush the current collecting lead 8, and the opening of the exterior body 5 is crimped. Then, the opening of the exterior body 5 is sealed with the sealing body 6. Thereby, a cylindrical nickel-metal hydride storage battery is manufactured.

  Here, as the current collecting leads 8 described above, those made of nickel-plated steel plates having thicknesses of 0.35 mm, 0.25 mm, and 0.20 mm are prepared, and these current collecting leads 8 are formed with the thickness (height). ) Was crushed so as to decrease by 2.0 mm, and a nickel metal hydride storage battery was manufactured (samples A, B, and C). For comparison, a nickel-metal hydride storage battery incorporating the current collector lead 8 having a plate thickness of 0.20 mm was manufactured using the current collector 7 formed with the tongue piece 7a on the negative electrode side (sample D). When these nickel-metal hydride storage batteries (samples A, B, C, and D) were subjected to dischargeability evaluation and vibration test, the following results were obtained.

  For the evaluation of discharge performance, 50% charge is performed with respect to the battery capacity at a temperature of 25 ° C. at 1 It, and after leaving for 1 hour in an open circuit state, 200 A discharge is performed for 10 seconds, and the battery voltage at this time is discharged. Characteristics were evaluated. Then, using a vibration test device, 250 Hz vibrations were applied to the nickel-metal hydride storage battery in the vertical and horizontal directions for two days each, and then the battery was disassembled and welded at the bottom of the can. The presence or absence was confirmed. Moreover, about these tests, 20 pieces were performed for every nickel hydride storage battery (sample A, B, C, D) mentioned above.

  From this performance test result, it was confirmed that there was no significant decrease in the discharge voltage for the samples A, B, and C of the nickel metal hydride batteries. It was confirmed that the welding with the body 7 did not come off. In addition, since the decrease in the discharge voltage occurs only when the current collector 7 having the tongue piece 7b is used, it is confirmed that the presence of the tongue piece 7b increases the battery resistance and is caused by this. did it. Therefore, it has been confirmed that it is necessary to use the current collector 7 that is not provided with the tongue piece 7b in order to realize a nickel metal hydride storage battery (alkaline storage battery) suitable for a large current application.

  And when attention is paid to the nickel-metal hydride storage battery (samples A, B, C) using the current collector 7 that does not have the tongue piece 7b, the stress absorbing action in the current collector 7 cannot be expected, and exclusively, Since it is considered that a stress absorbing action occurs in the current collecting lead 8 and only the nickel-metal hydride storage battery of sample C is detached from welding, when the current collecting lead 8 having a thin plate thickness is used. It is considered that the elastic force is insufficient and the vibration absorbing function is not sufficiently exhibited. In other words, it is the nickel metal hydride storage battery (sample) that uses the current collecting lead 8 having an elastic modulus of 97.7 (N / mm) or more that the current collecting lead 8 exhibits sufficient elastic force to absorb vibration. A, B) was confirmed.

Incidentally, the elastic coefficient C (N / mm) of the current collecting lead 8 is the amount of crushing A (mm) and the crushing load B when the current collecting lead 8 is crushed by applying a load as shown in FIG. (N) relationship, ie
C (N / mm) = B (N) / A (N)
Is defined as

  Therefore, when the battery resistance is reduced by using the current collector 7 not provided with the tongue piece 7b based on the performance test results described above and a nickel metal hydride storage battery suitable for high power use is realized, 97.7 (N / mm) or more. By using the current collecting lead 8 having an elastic modulus of 2 mm, vibration of the spiral electrode group 4 in the outer body 5 is suppressed, and stress concentration on the bottom of the can of the outer body 5 is prevented, thereby preventing current collection from the outer body 5 and the current collector. It was confirmed that the welding with the body 7 could be prevented from coming off.

  The present invention is not limited to the embodiment described above. For example, the present invention can be similarly applied to an alkaline storage battery having a structure in which the current collector 7 on the positive electrode side is omitted and the current collecting lead 8 is directly welded to the tab portion of the positive electrode 14 in the spiral electrode group 4. Further, here, the case where the current collecting lead 8 having a bent portion and exhibiting an elastic action, which is composed of a conductor piece bent in a substantially U shape or a conductor ring having a substantially oval cross section has been described as an example. Needless to say, the present invention can also be applied to the case where the current collecting lead 8 having the shape is used. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

The figure which shows schematic structure of the alkaline storage battery which concerns on one Embodiment of this invention. The figure which shows the example of the electrical power collector provided with the tongue piece for vibration absorption. The figure which shows the example of the electrical power collector which is not provided with a slice. The figure which shows the manufacture process of the alkaline storage battery which concerns on one Embodiment of this invention, especially the sealing process of the electrode group to an exterior body. The figure which shows typically the relationship between crushing of a current collection lead, and its elastic modulus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode body 2 Negative electrode body 3 Separator 4 Spiral electrode group 5 Exterior body (exterior can)
6 Sealing body 7 Current collector 8 Current collector lead

Claims (2)

An electrode group in which a sheet-like positive electrode body and a negative electrode body are wound via a separator;
A current collector welded to the one electrode body led to one end of the electrode group and integrated with the electrode group;
A bottomed cylindrical exterior body that houses the electrode group and is electrically connected to the current collector;
A current collecting lead that has a bent portion that exhibits an elastic action, is welded to the other electrode body led to the other end of the electrode group, and is attached to the electrode group;
A sealing body that is electrically connected to the current collecting lead and insulated from the exterior body so as to cover the opening of the exterior body,
As the current collecting lead, an elastic coefficient C (= B / A) indicated by a crushing load B [N] and a crushing amount A [mm] of the current collecting lead is approximately 97.7 [N / mm] or more. An alkaline storage battery characterized by using.   The current collecting lead is formed by crushing between opposing portions of a conductor piece bent in a substantially U shape or a conductor ring having a substantially oval cross section and giving an elastic force in the crushing direction. The alkaline storage battery according to claim 1.

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