JP2013134940A - Cylindrical battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical battery in which the possibility that internal short circuit occurs due to burrs at the side end of a positive electrode plate is low.SOLUTION: A nickel-hydrogen secondary battery 1 includes a positive electrode plate 21 holding a positive electrode active material, a negative electrode plate 22 holding a negative electrode active material, and a separator 23 separating the positive electrode plate 21 and the negative electrode plate 22. An electrode body 20 formed by winding the positive electrode plate 21 and the negative electrode plate 22 while superimposing with the separator 23 interposed therebetween is housed in a bottomed cylindrical outer can 10 of the cylindrical battery, and the widths W1-W3 of the negative electrode plate 22 are shorter than the width W4 of the positive electrode plate 21.

Description

  The present invention includes a positive electrode plate that holds a positive electrode active material, a negative electrode plate that holds a negative electrode active material, a separator that separates the positive electrode plate and the negative electrode plate, and the positive electrode plate and the negative electrode plate are overlapped via the separator to form a spiral shape. The present invention relates to a cylindrical battery in which an electrode body wound around is accommodated in a bottomed cylindrical outer can.

  A positive electrode plate that holds a positive electrode active material, a negative electrode plate that holds a negative electrode active material, and a separator that separates the positive electrode plate and the negative electrode plate, and the positive electrode plate and the negative electrode plate that are wound in a spiral shape via the separator Cylindrical nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and the like whose bodies are housed in a cylindrical can with a bottomed shape are known.

  Such a cylindrical battery may cause an internal short circuit due to its structure. As one aspect of the internal short circuit, the side edge of the positive electrode plate protrudes outside the side edge of the separator due to winding deviation when forming the electrode body, and the side edge of the positive electrode plate protruding outside the side edge of the separator is the negative electrode. May come into contact with plates or outer cans. And the amount of deviation of the winding deviation of the electrode body is maximized at the outermost peripheral portion of the electrode body at the end of winding because the deviation amount is accumulated as it is wound. Therefore, an internal short circuit due to winding deviation is most likely to occur at the outermost peripheral portion of the electrode body.

  As a prior art aimed at reducing the risk of internal short circuit due to such winding deviation, the height (width) of the positive electrode plate at the outermost peripheral portion of the electrode body is set to the width of the positive electrode plate at other portions. A cylindrical nickel-metal hydride secondary battery having a lower height is known (see, for example, Patent Document 1). The related art reduces the possibility that the side edge of the positive electrode plate protrudes outside the side edge of the separator due to winding deviation by reducing the height (width) of the positive electrode plate at the outermost peripheral portion of the electrode body. An object of the present invention is to reduce the risk of an internal short circuit due to winding deviation.

JP 2002-008710 A

  Since a positive electrode plate of a cylindrical battery generally uses a porous metal body having a three-dimensional network structure as a core, burrs are likely to occur at the side edges. Therefore, in the cylindrical battery, in addition to the internal short circuit due to the winding deviation as described above, the burr generated at the side edge of the positive electrode plate penetrates the separator and protrudes toward the negative electrode plate, and the burr contacts the negative electrode plate. This may cause an internal short circuit. The above prior art is ineffective against internal short-circuits caused by burrs on the side edges of the positive electrode plate. Rather, the positive electrode plate is formed at the outermost peripheral portion of the electrode body in which the height (width) of the positive electrode plate is reduced. There is even a possibility that the possibility of an internal short circuit due to burrs on the side edges of the side increases.

  And the internal short circuit resulting from winding misalignment can be reduced by making winding misalignment hard to produce, for example by the improvement of the winding apparatus which manufactures an electrode body, a device, etc. However, in a positive electrode plate using a porous metal body having a three-dimensional network structure as a core, it is difficult to prevent burrs from occurring at the side edges, and this is caused by burrs at the side edges of the positive electrode plates. The problem is how to reduce the internal short circuit.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a cylindrical battery that is less likely to cause an internal short circuit due to burrs on the side edges of the positive electrode plate.

<First Aspect of the Present Invention>
A first aspect of the present invention includes a positive electrode plate holding a positive electrode active material, a negative electrode plate holding a negative electrode active material, a separator separating the positive electrode plate and the negative electrode plate, and the positive electrode plate via the separator And the negative electrode plate is a cylindrical battery in which a spirally wound electrode body is housed in a bottomed cylindrical outer can, wherein the width of the negative electrode plate is shorter than the width of the positive electrode plate. It is the cylindrical battery characterized.

  Here, the width of the positive electrode plate is the winding direction when the positive electrode plate and the negative electrode plate are overlapped with a separator and wound in a spiral shape to form an electrode body (hereinafter simply referred to as “winding direction of the electrode body”). The length of the positive electrode plate in the direction intersecting with. Moreover, the width | variety of a negative electrode plate means the length of the negative electrode plate of the direction which cross | intersects the winding direction of an electrode body.

  In the first aspect of the present invention, in the electrode body, the width of the negative electrode plate is shorter than the width of the positive electrode plate. Therefore, the side edges of the positive electrode plate (both ends of the positive electrode plate in the direction intersecting with the winding direction of the electrode body; hereinafter the same) are the side edges of the negative electrode plate (both ends of the negative electrode plate in the direction intersecting with the winding direction of the electrode body). The same shall apply hereinafter). Therefore, even if a burr generated at the side edge of the positive electrode plate breaks through the separator and protrudes toward the negative electrode plate, the burr protrudes outward from the side edge of the negative electrode plate. This can reduce the possibility of an internal short circuit.

  Thereby, according to the 1st aspect of this invention, the effect that the cylindrical battery with little possibility of an internal short circuit arising from the burr | flash of the side edge of a positive electrode plate can be provided is acquired.

<Second Aspect of the Present Invention>
According to a second aspect of the present invention, in the first aspect of the present invention described above, the negative electrode plate corresponds to an innermost peripheral portion corresponding to an innermost peripheral portion of the electrode body and an outermost peripheral portion of the electrode body. Including an intermediate portion corresponding to a portion other than the outermost peripheral portion, the innermost peripheral portion, and the outermost peripheral portion, wherein the innermost peripheral portion and the outermost peripheral portion are shorter in width than the intermediate portion. It is a cylindrical battery.

  As the negative electrode plate, a metal plate such as punching metal is generally used as the core. Therefore, when the electrode body is constructed in the manufacturing process of the cylindrical battery, the innermost peripheral part (the part to start winding) of the electrode body having the smallest winding diameter and the largest curvature is formed into a smooth circular shape with a constant curvature. It is often difficult to wind. Accordingly, in many cases, the winding start portion when the electrode body is formed must be wound, for example, by bending the innermost peripheral portion of the negative electrode plate stepwise. In that case, in the innermost peripheral portion of the electrode body, the negative electrode plate is not in surface contact with the separator, and the bent portion of the negative electrode plate is in point contact with the separator. As a result, the negative electrode plate presses the separator against the positive electrode plate at a locally high contact pressure at the innermost peripheral portion of the electrode body, so that burrs on the side edges of the positive electrode plate penetrate the separator and protrude toward the negative electrode plate side. The potential will increase.

  Also, the outermost peripheral part of the electrode body has the largest amount of winding deviation, so when the burr generated at the side edge of the positive electrode plate breaks through the separator and protrudes toward the negative electrode plate, the burr contacts the negative electrode plate. Will most likely be.

  That is, an inner short circuit due to burrs at the side edges of the positive electrode plate is more likely to occur in the innermost peripheral portion and the outermost peripheral portion of the electrode body than in other portions.

  In the negative electrode plate of the second aspect of the present invention, the width of the innermost peripheral portion corresponding to the innermost peripheral portion of the electrode body and the outermost peripheral portion corresponding to the outermost peripheral portion of the electrode body corresponds to the other portions. It is shorter than the width of the middle part. That is, in the negative electrode plate of the second aspect of the present invention, the width of the innermost peripheral part of the electrode body and the part corresponding to the outermost peripheral part of the electrode body in which internal short circuit due to burrs on the side edges of the positive electrode plate is relatively likely to occur. It has a shorter shape. As a result, in the innermost peripheral portion and the outermost peripheral portion of the electrode body, the gap between the burr at the side edge of the positive electrode plate that breaks through the separator and protrudes toward the negative electrode plate side and the side end of the negative electrode plate becomes wider. The possibility that an internal short circuit occurs due to contact with the negative electrode plate can be further reduced.

<Third Aspect of the Present Invention>
A third aspect of the present invention is a cylindrical battery according to the second aspect of the present invention described above, wherein the innermost peripheral portion has a density of the negative electrode active material lower than that of the intermediate portion. is there.

  According to the third aspect of the present invention, by reducing the density of the negative electrode active material in the innermost peripheral portion of the negative electrode plate, the flexibility of the portion can be increased, so the winding diameter is the smallest and the curvature is the most. Winding of the innermost peripheral portion of the large electrode body is facilitated. Thereby, in the innermost peripheral portion of the electrode body, it is possible to reduce the possibility that the negative electrode plate is in a state of pressing the separator against the positive electrode plate with a locally high contact pressure. In other words, in the innermost peripheral part of the electrode body, it is possible to reduce the possibility that the burr at the end of the positive electrode plate breaks through the separator and protrudes toward the negative electrode plate. The possibility of occurring can be further reduced. In addition, the roundness of the electrode body can be increased by facilitating the winding process of the innermost part of the electrode body, so the electrode body is inserted into a bottomed cylindrical outer can in the cylindrical battery manufacturing process. In doing so, the risk of poor insertion can be reduced.

<Fourth aspect of the present invention>
According to a fourth aspect of the present invention, in the second or third aspect of the present invention described above, the outermost peripheral portion has a density of the negative electrode active material lower than that of the intermediate portion. It is a cylindrical battery.

  As described above, an internal short circuit due to burrs at the side edges of the positive electrode plate is more likely to occur in the outermost peripheral portion of the electrode body than in other portions. And by reducing the density of the negative electrode active material in the outermost peripheral portion of the negative electrode plate, the flexibility of the portion can be increased, so that the contact surface between the positive electrode plate and the negative electrode plate which are in contact via the separator is likely to be in surface contact. Become. As a result, the pressure acting from the negative electrode plate to the contact surface between the separator and the positive electrode plate becomes almost uniform at the outermost peripheral portion of the electrode body, reducing the possibility that the separator is pressed against the positive electrode plate with a strong local pressure. can do. In other words, in the outermost peripheral part of the electrode body where internal short circuit is relatively likely to occur, it is possible to reduce the possibility that burrs on the side edges of the positive electrode plate will break through the separator and protrude toward the negative electrode plate side. The possibility of an internal short circuit due to the burr can be further reduced.

  According to the present invention, it is possible to provide a cylindrical battery that is less likely to cause an internal short circuit due to burrs on the side edges of the positive electrode plate.

The perspective view which illustrated the longitudinal cross-section of the nickel-hydrogen secondary battery. Sectional drawing which shows the connection part of the positive electrode plate, positive electrode current collecting plate, and negative electrode plate, and negative electrode current collecting plate in a nickel hydride secondary battery. FIG. 2 is a cross-sectional view of the nickel metal hydride secondary battery taken along the line I-I in FIG. 1. The front view of a negative electrode plate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Configuration of nickel metal hydride secondary battery>
The configuration of the nickel metal hydride secondary battery 1 will be described with reference to FIGS.
FIG. 1 is a perspective view illustrating a longitudinal section of a nickel metal hydride secondary battery 1. FIG. 2 is a plan view illustrating a cross section of the nickel metal hydride secondary battery 1. FIG. 3 is a cross-sectional view of the nickel metal hydride secondary battery 1 taken along the line II of FIG.

  A cylindrical nickel-hydrogen secondary battery 1, which is an example of a “cylindrical battery”, includes an outer can 10, an electrode body 20, and a lid structure 30. The outer can 10 is a bottomed cylindrical member having one end opened and has conductivity. The electrode body 20 is formed in a substantially cylindrical shape by winding the positive electrode plate 21 and the negative electrode plate 22 in a spiral shape with a separator 23 interposed therebetween. The lid structure 30 is a structure that closes the opening of the outer can 10. The nickel metal hydride secondary battery 1 is configured in such a manner that an electrode body 20 is accommodated in an outer can 10 and further filled with an alkaline electrolyte (not shown), and an opening of the outer can 10 is closed by a lid structure 30. .

  The positive electrode plate 21 is a non-sintered nickel electrode, and includes a positive electrode core (not shown) and a positive electrode mixture held on the positive electrode core. The positive electrode core body is made of a metal material having alkali resistance and has a felt-like three-dimensional network structure made of metal fibers. As the metal material having alkali resistance, for example, nickel can be used. The positive electrode mixture includes positive electrode active material particles, various additive particles for improving the characteristics of the positive electrode plate, and a binder for binding mixed particles of these positive electrode active material particles and additive particles to the positive electrode core. Consists of.

  The positive electrode active material particles are nickel hydroxide particles. The nickel hydroxide particles may be higher-order nickel hydroxide particles having an average nickel valence of greater than 2. Further, the nickel hydroxide particles may be solid-solved with cobalt, zinc, cadmium or the like, or the surface may be coated with a cobalt compound. As the additive, in addition to yttrium oxide, cobalt compounds such as cobalt oxide, metal cobalt, and cobalt hydroxide, zinc compounds such as metal zinc, zinc oxide, and zinc hydroxide, rare earth compounds such as erbium oxide, and the like can be used. . As the binder, a hydrophilic or hydrophobic polymer or the like can be used. More specifically, the binder may be at least one selected from hydroxypropyl cellulose (HPC), carboxymethyl cellulose (CMC), and sodium polyacrylate (SPA). For example, the binder may be 0.1 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the positive electrode active material particles.

  The negative electrode plate 22 is formed by holding a negative electrode mixture on a conductive negative electrode core (not shown) having a strip shape. The negative electrode core is made of a sheet-like metal material having a plurality of through holes. For example, a punching metal, a metal powder sintered body substrate, an expanded metal, a nickel net, or the like can be used. In particular, a metal powder sintered body substrate obtained by molding punched metal or metal powder and then sintering it is suitable for the negative electrode core.

The negative electrode mixture as the “negative electrode active material” includes hydrogen storage alloy particles capable of occluding and releasing hydrogen and a binder. The hydrogen storage alloy particles may be any particles as long as they can store hydrogen generated electrochemically in an alkaline electrolyte during battery charging and can easily release the stored hydrogen during discharge. Such a hydrogen storage alloy is not particularly limited. For example, an AB ₅ type alloy such as LaNi ₅ or MmNi ₅ (Mm is a misch metal) can be used. Further, the negative electrode mixture may be a cadmium compound, for example, instead of the hydrogen storage alloy. As the binder, for example, a hydrophilic or hydrophobic polymer can be used.

  As the separator 23, for example, a polyamide fiber nonwoven fabric or a polyolefin fiber nonwoven fabric such as polyethylene or polypropylene provided with a hydrophilic functional group can be used as a material.

  The lid structure 30 includes a lid plate 31, an insulating gasket 32, a valve body 33, a positive electrode terminal 34, a compression coil spring 35, a positive electrode lead 36, and a positive electrode current collector plate 37. The lid plate 31 has a substantially circular shape, and a valve hole 311 is provided at the center. The cover plate 31 is fixed to the outer can 10 by caulking the opening edge of the outer can 10 with the insulating gasket 32 interposed therebetween. The valve body 33 is a member in which rubber and a metal plate are bonded together, and is provided on the outer surface of the lid plate 31 so as to close the valve hole 311. The positive electrode terminal 34 has a cylindrical shape with a flange, and is fixed so as to cover the valve element 33. The compression coil spring 35 is accommodated in the positive electrode terminal 34 and biases the valve body 33. The positive electrode lead 36 is provided in a bent state, and one end is welded to the inner surface of the lid plate 31 and the other end is welded to the positive electrode current collector plate 37. The positive electrode current collector plate 37 is a disk-shaped member, and a hole 371 for injecting an alkaline electrolyte into the outer can 10 is formed in the center.

  The positive electrode core of the positive electrode plate 21 has a connecting portion 211 formed at the end on the positive electrode current collector plate 37 side. A strip-shaped metal thin plate 212 made of a nickel ribbon or the like is fixed to the inner surface in the radial direction of the connecting portion 211 by welding or a conductive adhesive, for example. The thin metal plate 212 protrudes from the connecting portion 211 and is in contact with the positive electrode current collector plate 37. That is, the positive electrode current collector plate 37 and the positive electrode plate 21 are electrically connected via the thin metal plate 212. On the other hand, the negative electrode plate 22 is electrically connected to the outer can 10 while being in contact with the inner peripheral surface of the outer can 10 that forms the negative electrode terminal of the nickel-hydrogen secondary battery 1.

<Structure of negative electrode plate>
The structure of the negative electrode plate 22 of the nickel-hydrogen secondary battery 1 according to the present invention will be described with reference to FIG.
FIG. 4 is a front view of the negative electrode plate 22, in which the negative electrode plate 22 is illustrated by a solid line, and the positive electrode plate 21 is illustrated by a one-dot chain line.

  In the electrode body 20, a separator 23 (not shown in FIG. 4) is interposed, and the positive electrode plate 21 and the negative electrode plate 22 are generally overlapped in the positional relationship shown in FIG. To the end B of the winding from the winding direction X. Further, the electrode body 20 is configured so that the negative electrode plate 22 is wound inside, and the length of the negative electrode plate 22 in the winding direction X is longer than the length of the positive electrode plate 21 in the winding direction. The outermost peripheral portion is constituted by the negative electrode plate 22.

  The negative electrode plate 22 is a part other than the innermost peripheral part 221 corresponding to the innermost peripheral part of the electrode body 20, the outermost peripheral part 222 corresponding to the outermost peripheral part of the electrode body 20, the innermost peripheral part 221, and the outermost peripheral part 222. Includes an intermediate portion 223 corresponding to. The width W1 of the innermost peripheral portion 221 of the negative electrode plate 22, the width W2 of the outermost peripheral portion 222 of the negative electrode plate 22, and the width W3 of the intermediate portion 223 of the negative electrode plate 22 are all shorter than the width W4 of the positive electrode plate 21. Therefore, the side end of the positive electrode plate 21 is located outside the side end of the negative electrode plate 22. Therefore, even if a burr generated at the side end of the positive electrode plate 21 breaks through the separator 23 and protrudes toward the negative electrode plate 22 side, the burr at the side end of the positive electrode plate 21 protrudes outside the side end of the negative electrode plate 22. Therefore, the possibility that the burr contacts the negative electrode plate 22 to cause an internal short circuit can be reduced. Thus, according to the nickel metal hydride secondary battery 1 according to the present invention, it is possible to reduce the possibility of an internal short circuit due to burrs at the side edges of the positive electrode plate 21.

  Further, in the negative electrode plate 22, the width W1 of the innermost peripheral portion 221 and the width W2 of the outermost peripheral portion 222 are both shorter than the width W3 of the intermediate portion 223. In other words, the negative electrode plate 22 has an innermost peripheral portion 221 and an outermost peripheral portion corresponding to the innermost peripheral portion and the outermost peripheral portion of the electrode body 20 that are relatively susceptible to internal short circuit due to burrs on the side edges of the positive electrode plate 21. The widths W1 and W2 of 222 are shorter than the width W3 of the intermediate portion 223. This is not an essential component of the present invention. However, the innermost peripheral portion and the outermost peripheral portion of the electrode body 20 are relatively short-circuited due to burrs on the side edges of the positive electrode plate 21 as described above. Such a configuration is preferable because it is easy. With such a configuration, at the innermost and outermost peripheral portions of the electrode body 20, burrs at the side edges of the positive electrode plate 21 that penetrate the separator 23 and protrude toward the negative electrode plate 22 side and the side edges of the negative electrode plate 22. Therefore, the possibility that the burr contacts the negative electrode plate 22 to cause an internal short circuit can be further reduced.

<Other embodiments and modifications>
The present invention is not particularly limited to the embodiments described above, and it goes without saying that various modifications are possible within the scope of the invention described in the claims.

  For example, in addition to the above embodiment, the negative electrode plate 22 preferably has a density of the negative electrode active material in the innermost peripheral portion 221 corresponding to the innermost peripheral portion of the electrode body 20 lower than the density of the negative electrode active material in the intermediate portion 223. . The density of the negative electrode active material of the negative electrode plate 22 can be increased or decreased by adjusting the pressure during rolling in the rolling process of the manufacturing process of the negative electrode plate 22, for example.

  By adopting such a configuration, the flexibility of the innermost peripheral portion 221 of the negative electrode plate 22 can be increased, so that the innermost peripheral portion of the electrode body 20 having the smallest winding diameter and the largest curvature can be easily wound. become. Thereby, in the innermost peripheral portion of the electrode body 20, it is possible to reduce the possibility that the negative electrode plate 22 is in a state of pressing the separator 23 against the positive electrode plate 21 with a locally high contact pressure. That is, in the innermost peripheral portion of the electrode body 20, it is possible to reduce the possibility that the burrs at the end of the positive electrode plate 21 break through the separator 23 and protrude toward the negative electrode plate 22. The possibility of causing an internal short circuit can be further reduced. In addition, the roundness of the electrode body 20 can be increased by facilitating the winding process of the innermost peripheral portion of the electrode body 20, and thus a bottomed cylindrical outer can in the manufacturing process of the nickel hydride secondary battery 1. When the electrode body 20 is inserted into the electrode 10, the possibility of poor insertion can be reduced.

  Further, for example, in addition to the above embodiment, the negative electrode plate 22 preferably has a density of the negative electrode active material in the outermost peripheral portion 222 corresponding to the outermost peripheral portion of the electrode body 20 lower than the density of the negative electrode active material in the intermediate portion 223. By adopting such a configuration, the flexibility of the outermost peripheral portion 222 of the negative electrode plate 22 can be increased, so that the contact surface between the positive electrode plate 21 and the negative electrode plate 22 that are in contact via the separator 23 is likely to be in surface contact. . As a result, the pressure acting on the contact surface between the separator 23 and the positive electrode plate 21 from the negative electrode plate 22 becomes substantially uniform at the outermost peripheral portion of the electrode body 20, and the separator 23 is pressed against the positive electrode plate 21 with a strong local pressure. The risk of becoming a state can be reduced. That is, it is possible to reduce the possibility that burrs at the side edges of the positive electrode plate 21 break through the separator 23 and protrude toward the negative electrode plate 22 side at the outermost peripheral portion of the electrode body 20 where internal short circuit is relatively likely to occur. The possibility of an internal short circuit due to burrs on the side edges of the plate 21 can be further reduced.

DESCRIPTION OF SYMBOLS 1 Nickel metal hydride secondary battery 10 Outer can 20 Electrode body 21 Positive electrode plate 22 Negative electrode plate 23 Separator 221 Innermost peripheral part 222 of negative electrode plate Outermost peripheral part 223 of negative electrode plate Intermediate part W1 of negative electrode plate Width W2 Width W3 of outermost periphery of negative electrode plate Width W4 of intermediate portion of negative electrode plate Width of positive electrode plate X Winding direction of electrode body

Claims (4)

A positive electrode plate that holds a positive electrode active material; a negative electrode plate that holds a negative electrode active material; and a separator that separates the positive electrode plate and the negative electrode plate, and the positive electrode plate and the negative electrode plate are overlapped via the separator and swirled. A cylindrical battery in which a wound electrode body is housed in a bottomed cylindrical outer can,
A cylindrical battery characterized in that a width of the negative electrode plate is shorter than a width of the positive electrode plate.   2. The cylindrical battery according to claim 1, wherein the negative electrode plate includes an innermost peripheral portion corresponding to an innermost peripheral portion of the electrode body, an outermost peripheral portion corresponding to an outermost peripheral portion of the electrode body, and the innermost peripheral portion. A cylindrical battery comprising an intermediate portion corresponding to a portion other than the outer peripheral portion and the outermost peripheral portion, wherein the innermost peripheral portion and the outermost peripheral portion are shorter in width than the intermediate portion.   3. The cylindrical battery according to claim 2, wherein the innermost peripheral portion has a density of the negative electrode active material lower than that of the intermediate portion.   4. The cylindrical battery according to claim 2, wherein the outermost peripheral portion has a density of the negative electrode active material lower than that of the intermediate portion. 5.

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