JP2005108535A - Cylindrical secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical secondary battery comprising an almost circle-shaped current collector plate on which a plurality of burring parts are formed, reducing the waste of the current collector material while maintaining high rate property. <P>SOLUTION: The positive electrode current collector 60 is formed into such a shape that at least a part of circle is cut off along a cord. A plurality of round holes 62 are scattered on the whole part of the base plate, and a burring part 62a is formed on the periphery of respective round holes 62. Burring parts 62a(y1), 62a(y2) most distant from a center point Po of the circle in + direction of y-axis are selected, and the position of the cord (line L1) for cutting on the original circle is positioned so as to contact the end part in + direction of the y-axis on the selected burring parts 62a(y1), 62a(y2). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cylindrical secondary battery such as an alkaline secondary battery, and more particularly to a cylindrical secondary battery including a substantially circular current collecting plate in which a plurality of burring portions are formed.

Cylindrical secondary batteries represented by alkaline secondary batteries such as nickel metal hydride batteries and nickel cadmium batteries generally use a spiral electrode body in which a sheet-like positive electrode plate and a negative electrode plate are wound via a separator. A disc-shaped current collector plate is disposed on one end surface, and this current collector plate is connected to a positive electrode plate or a negative electrode plate.
Normally, the current collector plate is produced by punching a steel plate, but in order to collect current evenly from the spiral electrode body, the current collector plate is formed in a circular shape in accordance with the end face shape of the electrode body.

By the way, in such a circular current collector plate, as described in Patent Document 1, a plurality of holes are drilled so that gas can pass through, and burring is performed on the periphery of each hole (the periphery of the hole is drawn). And the burring portion is welded to the positive electrode or the negative electrode. Then, by applying a burring process to the current collector plate, the contact between the positive electrode plate or the negative electrode plate and the current collector plate is improved, so that the current collecting function of the current collector plate, in particular, the high rate characteristic is excellent.
JP 2002-231216 A

Even in such a cylindrical secondary battery, it is basically required to reduce the cost.
By the way, when a current collector plate is industrially punched from a steel plate, a strip-shaped steel plate is used, and a large number of current collector plates are punched at a constant pitch in the longitudinal direction and the width direction. Therefore, when the shape of the current collector plate is circular, there is a problem that a lot of useless portions (material loss) that cannot be used as the current collector plate occurs when the current collector plate is punched from the steel plate.

On the other hand, FIG. 22 of Patent Document 1 describes a current collector plate having a shape in which a circular peripheral edge is partially cut. According to this, a material loss during production of the current collector plate is reduced. It can be reduced.
However, in the case of the current collector plate described in Patent Document 1, the burring portion that should have existed in the original circular current collector plate whose peripheral portion has not been cut is partially cut off. The current path for collecting current from the electrode plate on the outer peripheral portion is reduced and the current collecting function is lowered. As a result, the high rate characteristics of the cylindrical secondary battery are degraded.

  In view of the above problems, the present invention reduces waste of current collector plate material while maintaining high rate characteristics in a cylindrical secondary battery having a substantially circular current collector plate having a plurality of burring portions. The purpose is to do.

In order to solve the above problems, in the cylindrical secondary battery according to the present invention, the current collector plate has a shape in which at least a part of a circle is cut out along a string.
When setting the position of the string forming the notch with respect to the original circular current collector plate not forming the notch, a plurality of burring portions existing in the original circular current collector plate Among these, the burring part close to the position where the notch is formed is set so as to be located on the outer side or in contact with the outer side.

  Here, with respect to the cutout position of the current collector plate with respect to the circle, it is preferable to cut the cutout at a position facing the circle in one direction across the center. Furthermore, it is preferable that the circle is notched at a position facing the direction perpendicular to one direction across the center.

As described above, according to the cylindrical secondary battery of the present invention, the current collector plate has a shape in which at least a part of the circle is cut out along the string. Compared with a circular current collector plate, the amount of material used can be reduced by the amount of the cutout, and the current collector plate can also be narrowed.
In addition, the chord forming the notch portion is positioned more outward than the burring portion adjacent to the position where the notch is formed among the plurality of burring portions existing in the original circular current collector plate. Therefore, as compared with the original circular current collector plate, the burring portion that becomes the current flow path remains as it is.

Therefore, compared with the case where a circular current collector plate is used in the cylindrical secondary battery, waste of materials used for manufacturing the current collector plate can be reduced while ensuring high rate characteristics in the same manner.
Furthermore, since the notch is formed along the string, the strength of the current collector plate is ensured, and the process of punching the current collector plate can be easily performed.
As for the notch position with respect to the circle, it may be cut along the chord only at a part on the circumference, but if it is cut out at two or more parts on the circumference, it is effective in reducing material loss. Is.

In particular, as described above, if the notch is cut out at a position facing the circle in one direction across the center, the width of the current collector plate in the direction can be reduced by the notch. Therefore, when punching from a steel plate, the punching pitch in one direction can be narrowed, and the number of positive current collector plates punched can be increased accordingly.
Furthermore, if the circle is notched even at a position facing the direction perpendicular to one direction across the center, the width of the current collector plate can be narrowed in two directions perpendicular to each other. Therefore, when punching from a steel plate, the punching pitch in two directions can be narrowed, and the number of positive current collector plates punched can be increased accordingly.

Hereinafter, an embodiment of a cylindrical secondary battery (hereinafter simply referred to as “battery”) according to the present invention will be described with reference to the drawings.
(1) Overall Configuration of Battery FIG. 1 is a cross-sectional perspective view of a battery according to the present embodiment.
As shown in the figure, the battery includes a spiral electrode body 1, an outer can 2, a sealing body 3, and the like, and a gasket 41 in which the outer can 2 in which the spiral electrode body 1 is accommodated and the sealing body 3 is an insulator. It is sealed by caulking through.

The spiral electrode body 1 includes a positive electrode plate 10, a negative electrode plate 20, and a separator 30, and the positive electrode plate 10 and the negative electrode plate 20 are wound through the separator 30.
For example, the positive electrode plate 10 is impregnated with a positive electrode active material mainly composed of nickel hydroxide and dried with respect to a nickel sintered substrate formed by sintering nickel powder in punching metal, and then having a predetermined thickness. It is a sheet-like sintered electrode plate rolled until. The negative electrode plate 20 is, for example, a sheet-like hydrogen storage alloy negative electrode plate that is filled with a paste-like negative electrode active material made of a hydrogen storage alloy in punching metal, dried, and then rolled to a predetermined thickness. The separator 30 is, for example, a sheet-like nonwoven fabric made of polyamide or the like, and a film or the like can be used in addition to the nonwoven fabric.

A current collecting tab 11 protruding from the positive electrode plate 10 is spirally exposed at the upper end portion (the end portion close to the sealing body 3) of the spiral electrode body 1. On the other hand, a current collecting tab 22 protruding from the negative electrode plate 20 is spirally exposed at the lower end of the spiral electrode body 1 (the end near the bottom of the outer can 2).
A positive current collector plate 60 welded and fixed to the current collecting tab 11 is disposed along the upper end surface of the spiral electrode body 1, and is welded and fixed to the current collecting tab 22 along the lower end surface of the spiral electrode body 1. A negative electrode current collector plate 70 is disposed.

The positive electrode current collector plate 60 has a lead portion 61 disposed on the upper surface thereof, and electrically connects the positive electrode plate 10 and the positive electrode terminal 310 via a sealing lid 31 that comes into contact therewith. As the configuration of the lead portion 61, lead portions having various shapes as described in Patent Document 1 can be used.
The negative electrode current collector plate 70 is disposed in contact with the bottom of the outer can 2 that also serves as a negative electrode terminal, and electrically connects the negative electrode plate 20 and the outer can 2.

The spiral electrode body 1 to which the current collector plates 60 and 70 are welded in this way is accommodated in the outer can 2 and then injected with an alkaline electrolyte.
The outer can 2 has a bottomed cylindrical shape, and its opening is sealed by a sealing body 3 via a gasket 41. The gasket 41 is made of an insulator and holds the outer can 2 and the sealing body 3 in an insulated state.

The sealing body 3 includes a sealing lid 31, a positive terminal 310, a valve plate 51, and a spring 53. Here, the valve plate 51 closes the hole opened in the central portion of the sealing lid 31 by pressing of the spring 53. When the pressure inside the battery increases, the valve plate 51 is pushed up to discharge the reaction gas into the atmosphere through the vent hole.
(2) Configuration of Positive Current Collector Plate 60 FIG. 2A is a perspective view of the positive current collector plate 60, and FIG. 2B is a cross-sectional view taken along the line AA ′ of FIG.

As shown in the figure, the positive electrode current collector plate 60 is a substantially disk-shaped substrate made of a conductive metal, and has a plurality of round holes 62 formed therein.
Each round hole 62 is formed with a burring portion 62 a that rises from the periphery in the thickness direction of the positive electrode current collector plate 60. The shape of the burring portion 62a is basically an annular shape, but the burring portion 62a applied to the outer periphery of the current collector plate 60 is a shape corresponding to a part of the annular shape.

And the front-end | tip part of these burring parts 62a and the spiral collector tab 11 are joined by resistance welding in the location which mutually opposes, and the positive electrode current collecting plate 60 can collect current from the positive electrode plate 10. FIG.
The plurality of round holes 62 are formed so as to be dispersed over the entire substrate of the positive electrode current collector plate 60, whereby a joint portion is secured over the entire spiral current collector tab 11, and the current collecting function is satisfactorily performed. be able to.

Further, in order to improve the current collecting function, the plurality of round holes 62 are arranged so as to be uniformly distributed in a region where the spiral current collecting tab 11 is present.
3 and 4 are plan views showing specific examples of the positive electrode current collector plate 60, respectively, as seen from the burring portion 62a side.
As shown in these drawings, each of the positive electrode current collector plates 60 has a substantially disc shape, and has a shape in which a circle is partially cut out along a string. That is, a string that forms each notch portion is set with respect to a circle before notch (virtual circle along the outer periphery of the positive electrode current collector plate 60), and the notch is notched along the string.

In the example of FIG. 3, it is cut out at two opposite locations on the circumference along the outer periphery, and in the example of FIG. 4, it is cut out at four locations on the circumference along the outer periphery.
However, the positional relationship between the strings forming the notches and the plurality of burring portions 62a is set so that the strings contact the outside of the burring portions 62a adjacent to the notched portions.
With reference to FIG. 3, the positional relationship between the strings forming the notches and the plurality of burring portions 62a will be described more specifically.

Here, the center point of the virtual circle in the positive electrode current collector plate 60 is P0, and the axis extending from the center point P0 in the direction in which the notch is to be formed is the y-axis. A method of setting the position of the string will be described assuming that a plurality of burring portions 62a are formed in the virtual circle.
Among the plurality of burring portions 62a existing in the virtual circle (including the burring portion 62a partially existing in the virtual circle), two burring portions 62a (y1) farthest from the center point P0 with respect to the y-axis direction, and The burring part 62a (y2) is selected.

In FIG. 3, the burring part 62a (y1) and the burring part 62a (y2) are selected.
Then, a straight line L1 may be set so that the selected burring portions 62a (y1) and 61a (y2) are in contact with the end on the y-axis + direction side. That is, the portion P1 farthest from the center point P in the y-axis + direction in the burring portion 62a (y1) and the portion P2 farthest in the y-axis + direction from the center point PO in the burring portion 62a (y2) are connected. A straight line L1 may be set in

In the example of FIG. 3, since the position of the straight line L1 is the string setting position as it is, the string is in contact with the outside of the burring portions 62a (y1) and 61a (y2).
In the example shown in FIG. 3, a string that forms a notch is also set in the same manner for the y-axis direction.
Further, in the positive electrode current collector plate 60 shown in FIG. 4, not only the y-axis direction but also the x-axis direction passing through P0 and perpendicular to the y-axis is cut out by the same method. The strings that form are set.

  That is, the burring portions 62a (x1) and 62a (x2) farthest in the x-axis + direction are selected, and the burring portion 62a (x1) and the portion P3 farthest in the x-axis + direction from the center point P0 In the portion 62a (x2), the position of the string is set so as to connect the portion P4 farthest from the center point P0 in the x-axis plus direction, and the string position is similarly set in the x-axis minus direction.

(3) Effect by using positive electrode current collector plate 60 The positive electrode current collector plate 60 has the following effects by being set in the above-mentioned shape.
In the positive electrode current collector plate 60, the outer edge from the center point P0 is compared with the circular positive electrode plate (virtual circular positive electrode plate shown by a broken line) where the cutout portion is not formed. (The width of the positive electrode current collector plate 60 in the y-axis + direction is narrower). Therefore, the material used when the current collector plate is punched from the steel plate can be considerably reduced to the notch portion.

Therefore, the positive electrode current collector plate 60 becomes lighter, and the manufacturing cost can be reduced by reducing the material used to manufacture the positive electrode current collector plate 60.
In addition, since the notched string is in contact with the outside of the adjacent burring portion 62a, the burring portion 62a included in the positive electrode current collector plate 60 is a circular positive plate (not illustrated with a broken line). This is equivalent to a burring portion 62a of a circular positive electrode plate).

Therefore, compared with a circular positive electrode current collector plate not having a notch, the same current collecting function can be ensured, and the high rate discharge characteristics when incorporated in a battery are also equivalent.
Regarding the effect of reducing the material loss due to the notch portion In the process of manufacturing the positive electrode current collector plate industrially, a strip-shaped steel plate is used as the current collector plate material, and drilling and burring are performed, so that the circular hole 62 and the burring portion 62a. Is formed by punching in the shape of the positive electrode current collector plate, but a single strip-shaped steel plate is punched at a constant pitch both in the longitudinal direction and in the width direction.

Therefore, if the width of the positive electrode current collector plate in one direction can be reduced, the punching pitch in the longitudinal direction or the width direction can be set to that extent, and the number of positive electrode current collector plates to be punched can be increased.
Furthermore, if the width of the positive current collector plate can be narrowed with respect to two directions orthogonal to each other, the punching pitch can be set to be narrower for both the longitudinal punching pitch and the width direction. The number can be increased.

Here, the original circular positive electrode current collector plate has the same width in any direction as the diameter of the circle, but if a notch is formed in one direction as shown in FIG. (Y-axis direction width) becomes narrower.
Therefore, as compared with the original circular positive electrode current collector plate, the punching pitch in the longitudinal direction or the width direction can be narrowed, and the number of positive electrode current collector plates punched can be increased accordingly.

Further, as shown in FIG. 4, when the cutout portions are formed in two directions orthogonal to each other, the widths in the two directions (the x-axis direction width and the y-axis direction width) are narrowed. Therefore, the punching pitch in the longitudinal direction and the punching pitch in the width direction can be made narrower and the number of positive electrode current collecting plates punched can be increased by that amount as compared with the original circular positive electrode current collecting plate.
(4) Modification of Embodiment When setting the position of the string forming the notch portion, the string may be set to be positioned outside the adjacent burring portion 62a. For example, in FIG. 3, the string may be set along a straight line L2 that is shifted in the y-axis + direction from the straight line L1, and in this case, a circular positive current collector plate that is not formed with a notch, In comparison, while ensuring an equivalent current collecting function, there is an effect of reducing the material used for manufacturing the positive electrode current collecting plate 60. However, the effect of reducing the material used is superior when the string is set to contact the outside of the adjacent burring portion 62a (the direction is set along the straight line L1 rather than the straight line L2). Further, when forming the cutout portion along the string, the edge of the cutout portion does not necessarily have to be a straight line, for example, it may have a gently curved shape or a meandering shape. The formation is preferable in that punching can be easily performed and the shape is simple.

  Moreover, in the said embodiment, although the case where a notch was provided about a positive electrode current collector plate was demonstrated, it can implement similarly also with respect to the negative electrode current collector plate which has a burring part.

Hereinafter, based on the above embodiment, the nickel metal hydride batteries of Examples 1 and 2 using the positive electrode current collector plate having the shape shown in FIGS. Further, a nickel-metal hydride battery of a comparative example using a circular positive electrode current collector plate without a notch was also produced. All the batteries produced have a nominal capacity of 6.0 Ah and a D size.
Hereinafter, a specific manufacturing method thereof will be described.

Production of spiral electrode body: A nickel positive electrode plate described in the above embodiment and a hydrogen storage alloy negative electrode plate are wound through a separator made of polypropylene nonwoven fabric so that the outermost periphery becomes a negative electrode plate, and a spiral electrode having a diameter of 30 mm The body was made.
A positive current collecting tab is exposed at one end of the spiral electrode body, and a negative current collecting tab is exposed at the other end.

Preparation of positive current collector plate:
The positive electrode current collector plate is formed by punching and burring a steel plate, which is a current collector plate material, to form a circular hole 62 and a burring portion 62a, which are formed as positive electrodes shown in FIGS. 5 (a) to 5 (c). It was produced by punching according to the shape of the current collector plate.
FIG. 5 is a plan view showing the shapes of the positive electrode current collector plates according to Examples 1 and 2 and the comparative example.

(A) The positive electrode current collector plate used in Example 1 has the same shape as that shown in FIG. 3, and is opposite to the circular current collector plate having a diameter of 30 mm at two opposite locations on the circumference. Notched along the string. And the width | variety (y-axis direction width | variety in FIG. 3) which connects two notch parts which oppose is 25 mm.
(B) The positive electrode current collector plate used in Example 2 has the same shape as that shown in FIG. 4, and is formed into a string at four locations on the circumference with respect to a disk current collector plate having a diameter of 30 mm. Notched along. The width connecting two pairs of notch portions (the width in the y-axis direction in FIG. 4) is 25 mm, and the width connecting two other notch portions facing each other (the width in the x-axis direction in FIG. 4) is It is 26.5 mm.

(C) The positive electrode current collector plate used in the comparative example has a circular shape with a diameter of 30 mm.
In addition, all the positive electrode current collecting plates were set so that the round hole and the burring portion were formed in the same manner.
Battery assembly:
Using the spiral electrode body produced as described above, each positive electrode current collector plate, and a separately produced negative electrode current collector plate, an outer can, and a sealing body, a battery was assembled as follows.

The positive electrode current collector plate was placed on one end side of the spiral electrode body and then pressed, so that the burring portion of the positive electrode current collector plate was cut into the current collector tab. Then, the burring part and the current collection tab were resistance-welded by flowing a welding current while pressing.
On the other hand, the current collector tab and the negative electrode current collector plate were resistance welded by causing a current to flow while the negative electrode current collector plate was brought into contact with the other end side of the spiral electrode body.

  The spiral electrode body to which the positive electrode and the negative electrode current collector plate were welded was inserted into the outer can so that the negative electrode current collector plate was on the lower side, and the negative electrode current collector plate and the bottom of the outer can were spot welded. Then, the current collecting lead was welded to the positive electrode current collecting plate, and the current collecting lead and the sealing body were welded and connected. Then, the electrolyte solution which consists of 30 mass% potassium hydroxide aqueous solution was inject | poured into the exterior can. Finally, the sealing body was disposed in the opening of the outer can through a gasket, and then the outer can was sealed by caulking to produce a nickel metal hydride battery.

[Experiment]
The IV characteristics (output characteristics) and the area and mass of the positive electrode current collector in each sample were measured, and the measurement results were considered.
The output characteristics of the batteries of Examples 1 and 2 and Comparative Example were measured using the following method.
First, it fully discharged until the battery capacity of each sample became 0 mAh. And it charged for 6 minutes at 6A, and was set as the charge condition used as a capacity | capacitance of about 50% with respect to battery capacity. Thereafter, the reaction was stopped for 1 hour to stabilize the chemical reaction inside the battery. And it discharged for 10 second at 30A, charged for 10 second at 30A 30 minutes after that, and measured the voltage value when this 10 second was reached. The external environment temperature at the time of charging / discharging is 25 degreeC.

Further, the same experiment was performed by changing the charge / discharge of 30A to 90A and 150A, and the voltage value at each current value was measured.
FIG. 6 is a graph plotting voltage values against current values in each sample.
The slope in this graph indicates the resistance value of the battery. From FIG. 6, it can be seen that the resistance values are equivalent because Examples 1, 2 and the comparative example have substantially the same inclination. It can also be seen that the high rate characteristics are equivalent. This is presumably because the positive electrode current collector plates according to Examples 1 and 2 and the comparative example have the same burring portion, so that the same current paths are formed in the battery.

Considering the material loss reduction at the time of punching out the positive electrode current collector plate, the positive electrode current collector plate according to the comparative example is a circle having a diameter of 30 mm. The width (y-axis direction width) is 25 mm.
Therefore, in the positive electrode current collector plate of Example 1, the punching pitch in the longitudinal direction or the width direction can be narrowed by 5 mm compared to the positive electrode current collector plate in the comparative example, and the number of positive electrode current collector plates punched can be increased accordingly.

  In the positive electrode current collector plate of Example 2, the width in one direction (y-axis direction width) is 25 mm, and the width in the direction orthogonal to this (x-axis direction width) is 26.5 mm. Therefore, in the positive electrode current collector plate of Example 2, as compared with the positive electrode current collector plate of the comparative example, one of the punching pitch in the longitudinal direction and the punching pitch in the width direction can be narrowed by 5 mm, and the other can be narrowed by 3.5 mm. The number of current collector plates can be increased.

FIG. 7 is a graph in which the planar areas of the positive electrode current collector plates in Example 1 and the comparative example are plotted, and FIG. 8 is a graph in which the masses of the positive electrode current collector plates are plotted.
As shown in both figures, it can be seen that Example 1 can reduce the area of the positive electrode current collector plate by 9.9 mm ² and the mass by 0.03 g compared to the comparative example.

INDUSTRIAL APPLICABILITY The present invention can be applied to a cylindrical secondary battery provided with a substantially circular current collector plate having a plurality of burring portions, and wastes current collector material during production while maintaining good high rate characteristics. This can reduce the cost.
Therefore, the present invention can be applied to alkaline secondary batteries such as nickel metal hydride batteries and nickel cadmium batteries, and other battery-type batteries such as lithium ion batteries. Is effective when applied to nickel hydride secondary batteries and nickel cadmium batteries that are required to have good high-rate characteristics at low cost.

1 is a cross-sectional perspective view of a cylindrical secondary battery according to the present invention. It is a perspective view of the positive electrode current collector plate according to the present invention. It is a top view of the positive electrode current collector plate according to the present invention. It is a top view of the positive electrode current collector plate according to the present invention. It is a top view of the positive electrode current collection plate used for the Example and the comparative example. It is a graph which shows the output characteristic concerning an Example and a comparative example. It is a graph which shows the plane area of the positive electrode current collecting plate concerning an Example and a comparative example. It is a graph which shows the mass of the positive electrode current collecting plate concerning an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spiral electrode body 2 Exterior can 3 Sealing body 10 Positive electrode plate 11 Current collecting tab 20 Negative electrode plate 22 Current collecting tab 30 Separator 60 Positive electrode current collecting plate 62 Round hole 62a Burring part 70 Negative electrode current collecting plate

Claims (3)

A spiral electrode body in which a positive electrode plate and a negative electrode plate are wound via a separator, and a current collector plate disposed along one end surface of the spiral electrode body and having a plurality of burring portions,
A cylindrical secondary battery in which the plurality of burring portions are in contact with end portions of the positive electrode plate or the negative electrode plate,
The current collector plate is
At least part of the circle
Among the plurality of burring portions, for the burring portion close to the portion,
A cylindrical secondary battery characterized by being cut out along a string set so as to be located on the outer side or in contact with the outer side. The current collector plate is
2. The cylindrical secondary battery according to claim 1, wherein the cylindrical secondary battery has a shape cut out at a position facing the circle in one direction across the center. The current collector plate is
3. The cylindrical secondary battery according to claim 2, wherein the cylindrical secondary battery is cut out at a position facing the circle in a direction perpendicular to the one direction across the center.

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