JP2001060456A - Metal-plate current collector and secondary battery using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal-plate current collector and a secondary battery, suitable for use with large current. SOLUTION: This metal-plate current collector 1 to be connected to an electrode substrate 10 of a rolled electrode group 9 and to a battery terminal part has a plurality of incision parts 5 extending from outer circumferential parts 3 of its metal plate 2 toward a middle part 4 thereof and an incision part 6 extending from the middle part 4 toward an outer circumferential part 3. The incision parts 5 each have a folded portion 7 while the incision part 6 has a folded portion 8. A tab 12 is provided on or near the middle part 4 of the metal- plate current collector 1, or an annular hole part 14 with at least a part closed is provided around the middle part 4 of the metal-plate current collector 1. The metal-plate current collector 1 is connected to the electrode substrate 10 of the rolled electrode group 9 by means of the folded portions 7 and folded portion 8 while it is connected to the battery terminal part by means of the tab 12 or the middle part 4 of the metal-plate current collector 1, thus forming a secondary battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal plate current collector joined to an electrode substrate of a wound electrode group and a terminal of a battery, and to a secondary battery using the metal plate current collector. TECHNICAL FIELD The present invention relates to a metal plate current collector and a secondary battery suitable for high current applications.

[0002]

2. Description of the Related Art Secondary batteries such as alkaline storage batteries and lithium secondary batteries are widely used as portable power supplies.
Generally, in these batteries, a part of the end face of the wound electrode group is connected to a metal terminal to extract current. For example, when used as a power source of a power tool, a large power of 10 A or more is required. In this case, a large current of about 50 A is used in some cases, so that it is necessary to reduce the internal resistance.

[0003] Therefore, in a nickel-cadmium battery, in order to reduce the internal resistance, each end face of a wound body electrode group formed by winding a positive electrode and a negative electrode through a separator is provided.
A method has been proposed in which a metal plate current collector terminal having a large number of openings and protruding edges formed by the openings is welded at a number of points, and a method is provided in which a comb-shaped welded portion is provided for welding.
No. 5172, Japanese Patent Publication No. 54-31575, etc.).

[0004]

By the way, the electrodes used in the battery intended to supply a large current as described above are:
For the purpose of reducing the internal resistance of the battery, it is necessary to make the length of the electrode in the winding direction longer than that of a normal battery electrode.
Further, in order to make the charge / discharge reaction of each part of such a long electrode uniform, it is preferable to collect current from a large number of points in which the intervals between welding points are distributed as uniformly as possible in the length direction of the electrode. .

[0005] However, the metal plate current collecting terminal proposed so far can collect current at a number of points, but is a current collector concentrated at a central portion in the longitudinal direction of the electrode, and has a winding shape. Since it is difficult to collect current from the innermost and outermost parts of the body electrode group, and because the diameter of the wound electrodes on the inner and outer circumferences of the wound body electrode group is different, Was short at the inner peripheral portion and widened at the outer peripheral portion, resulting in an uneven current collecting form.

The present invention reduces the non-uniformity of the current collecting state due to the current collecting portion when a metal plate current collector is used as a current collecting terminal, and uses the metal plate current collector suitable for large current application. To provide a secondary battery suitable for high current applications.

[0007]

Means for solving the above problems will be described with reference to, for example, FIGS. 1 to 3. The present invention provides an electrode substrate (10) and a wound electrode group (9). The metal plate current collector (1) to be joined to the terminal of the battery is provided with a plurality of cuts (5) extending from the outer peripheral portion (3) of the metal plate (2) toward the central portion (4) and the metal plate (2). Central part of (4)
, One notch (6) extending from the first portion to the outer peripheral portion (3), the notch (5) has a bent portion (7), and the notch (6) has a bent portion (8); In addition, a tab (12) is provided at or near the center (4) of the metal plate current collector (1), and the bent portion (7) and the bent portion (8) of the metal plate current collector (1) are provided.
And joined to the electrode substrate (10) of the wound electrode group (9) and to the terminal of the battery by the tab (12). The tab (12) is suitable to be joined to a battery cover constituting one terminal of the battery.

In the present invention, for example, as shown in FIG. 4, a metal plate current collector (1) joined to an electrode substrate (10) of a wound electrode group (9) and a terminal portion of a battery is formed as follows. A plurality of cuts (5) from the outer peripheral portion (3) of the metal plate (2) toward the central portion (4) and one notch from the central portion (4) of the metal plate (2) toward the outer peripheral portion (3). (6), the notch (5) has a bent portion (7), the notch (6) has a bent portion (8), and a central portion of the metal plate current collector (1). An annular hole (14) at least partially closed is provided around the periphery of (4), and the metal plate current collector (1) is formed of a winding body with a bent portion (7) and a bent portion (8). Joined to the electrode substrate (10) of the electrode group (9), and joined to the battery terminal at the center (4) of the metal plate current collector (1) In which was to so that. The central portion (4) of the metal plate current collector (1) is suitably joined to the bottom of a battery can that constitutes the other terminal of the battery.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the detailed description of the operation and the form of the metal plate current collector of the present invention, the problems in the case of using the conventional metal plate current collector will be described in detail. As shown in FIG. 7, the metal plate current collector has a large number of openings (132) formed in the metal plate (131). A protruding edge portion (133) for welding is formed. In general,
The metal plate current collector needs to be as thick as possible in order to reduce the internal resistance of the battery, while the protruding edge of the conventional metal plate current collector (130) is required. (133)
Is required to have a small difference in heat capacity from the electrode substrate to be welded, so that its thickness is required to be thin. Therefore, in the conventional metal plate current collector (130), the thickness of the protruding edge portion (133) is configured to be smaller than the thickness of the metal plate (131).

However, the opening (132) for welding to the electrode substrate of the wound electrode group of the conventional metal plate current collector (130) is formed by punching the metal plate (131). Therefore, from the viewpoint of maintaining the strength, it is a reality that the metal plate (131) can be provided only at an intermediate portion excluding an outer peripheral portion or an inner peripheral portion. for that reason,
In a wound electrode group for large current that requires a long electrode,
Despite the necessity of causing the charge and discharge reaction to be performed uniformly at each part of the electrode, welding points could not be obtained at the electrode substrates located at the inner and outer peripheral portions of the wound electrode group.

Further, as the metal plate current collector (130),
A tab (134) is provided on the metal plate (131) for connection with an electrode can or a battery lid constituting a terminal of the battery. At this time, in order to reduce resistance during energization, a welding portion and the tab (134) are provided. It is preferable that there is no discontinuous portion such as a notch that obstructs the flow of the current. However,
As shown in the current flow (141) of FIG. 8, the conventional metal plate current collector (130) has a tab (134) at any place.
However, there is a problem that the current is interrupted by the opening (132) when the power is supplied. Further, the opening (13)
Since 2) is circular, the protruding edge (13
In some cases, the protruding edge (133) and the electrode substrate of the wound electrode group to be welded are sufficiently in contact with each other, for example, a portion where the electrode substrate of the wound electrode group to be welded cannot contact the electrode substrate of the wound electrode group to be welded. However, there was a problem that welding failure was likely to occur.

As a solution for providing a welded portion at the outermost periphery of the wound electrode group, as shown in FIG. 9, a notch (from the outer periphery toward the center) is formed on the metal plate (151). 152), the end of the cutout (152) may be bent, and the bent portion (153) may be welded to the electrode substrate of the wound electrode group.

However, in such a metal plate current collector (150), although current can be collected at the outer peripheral portion of the wound electrode group, there is no welding point at the inner peripheral portion. In contrast, 1/4 to 1/3 have no welding points at all, and therefore are not a complete solution.

In view of such a situation, the present inventors have conducted various studies to solve the above problems, and as a result, as shown in FIGS. 1 to 3, the electrode substrate (10) of the wound electrode group (9). And a plurality of cuts (5) extending from the outer peripheral portion (3) of the metal plate (2) to the center portion (4) and the metal plate (2) in the metal plate current collector (1) joined to the terminal portion of the battery. ), One notch (6) extending from the central part (4) to the outer peripheral part (3) is provided, and the notch (5) and the notch (6) are respectively provided in the wound electrode group (9). By providing a bent portion (7) or a bent portion (8) with respect to the metal plate (2) for the purpose of bonding to the electrode substrate (10), a cut from the outer peripheral portion (3) toward the central portion (4). In part (5), a welding point is also formed at the outermost periphery of the wound electrode group At the notch (6) extending from the central portion (4) to the outer peripheral portion (3), it is also possible to form a welding point at the innermost peripheral portion of the wound electrode group. Was found. Also,
By making the metal plate current collector (1) have the above structure,
In the electrode located at the outermost periphery of the wound body electrode group, the interval between the welding points can be shortened, and the interval between the welding points of the electrodes on the inner periphery can be made closer. In addition, since the structure of the metal plate current collector (1) is as described above, the current at the time of energization is higher than that of the conventional metal plate current collector (130) in which only the opening is formed by punching. It is possible to reduce the discontinuous portion of the metal plate that hinders the flow of air. Further, both the bent portion (7) provided in the cut portion (5) and the bent portion (8) provided in the cut portion (6) are properly formed in a form close to a right angle to the electrode substrate (10). Since it is possible to make contact, the occurrence of poor bonding can also be reduced. The bent part (7) and the bent part (8) are shown in FIG.
As shown in FIGS. 3 to 3, they protrude substantially perpendicularly to the lower side of the metal plate (2). 1, 4, and 5, the state is indicated by a thick line.

In the metal plate current collector (1) of the present invention, the metal plate (2) has a plurality of cuts (5) extending from the outer peripheral portion (3) to the central portion (4) (ie, two or more cuts). It is necessary. That is, in the inner peripheral portion of the wound electrode group, since the diameter of the wound electrode group is small, even if one welding point is provided on each circumference of the wound body, the interval between the welding points does not become so large. However, since the notch (5) directed from the outer peripheral portion (3) toward the central portion (4) is mainly for welding to the outermost electrode of the wound electrode group, this notch is used. With only one (5), only one welding point at the outermost circumference can be formed per circumference, and the distance from the welding point at the outermost circumference to the next welding point is within one circumference having a large diameter circumference. Since the distance to the welding point on the peripheral side is obtained, the welding interval becomes extremely long, and uniform current collection cannot be performed when a large current wound electrode group that requires uniform current collection is used. However, as in the present invention, the notch (5)
By providing two or more, it is possible to form a welding point on at least one half of the wound electrode group even at the outermost peripheral portion, and uniform current collection can be performed similarly to the inner peripheral portion having a short welding interval. become able to.

On the other hand, the central part (4) of the metal plate current collector (1)
It is sufficient to provide one notch (6) from the metal plate (2) for the above-mentioned reason.
That is, when two notches (6) are provided, as shown in FIG. 6, the notches (5) extending from the outer peripheral portion (3) toward the central portion (4) by the increased number of the notches (6). Will decrease. This is not preferable because the number of welding points in the outer peripheral portion that requires more welding points is reduced. Further, the notch (6) is formed with a metal plate (2).
Although it is conceivable to extend the outer peripheral portion (3) to obtain a welding point as a whole, it is preferable not to perform the process from the viewpoint of securing the strength of the metal plate (2) and facilitating the handling.

According to the study of the present inventors, the length of the longest portion of the bent portion (7) of the cut portion (5) and the length of the longest portion of the bent portion (8) of the cut portion (6) are determined. The sum is 1 for the length (L) from the hole end (11) at the center of the metal plate (2) to the outer peripheral portion (3) of the metal plate (2).
It is preferable that the number be less than 2 or more. That is, by setting the sum of the lengths of the longest portions of the bent portions in the respective cut portions within the above range, the welding points are uniformly distributed on the electrodes.

The longest portion of the bent portion (7) and the longest portion of the bent portion (8) are defined as the length of the longest bent portion when there are a plurality of bent portions having different lengths at respective cut portions. Is meant. Further, when the ratio of the length of the bent portion (8) of the cut portion (6) to the length of the bent portion (7) of the cut portion (5) is set to be 0.8 or more and 1.2 or less, each cut portion has This is preferable because welding can be performed under the same conditions and the process can be simplified.

The metal plate current collector of the present invention can be used for both positive and negative electrode current collectors. However, the metal plate current collector on the side to be disposed above the wound electrode group and joined to the battery lid is used. The electric body is provided with a tab (12) as shown in FIG. This tab (12) is provided with a metal plate current collector (1) as shown in FIG.
By providing it in the central portion (4) or in the vicinity thereof, it is possible to lower the resistance of the current collecting portion. In providing the tab (12), resistance welding, ultrasonic welding, or the like can be employed for joining the tab (12) to the metal plate (2).

The hole (13) at the center of the metal plate current collector (1) is formed by welding the electrode substrate (10) of the wound electrode group (9) and the metal plate current collector (1). This is for injecting an electrolytic solution after joining.

As for the metal plate current collector on the side to be joined to the battery can provided below the wound electrode group, the central part (4) is joined to the bottom of the battery can. As shown in FIG. 4, it is necessary to provide an annular hole (14) at least partially closed, such as a U-shaped hole, around the central portion (4) of the metal plate current collector (1). . That is, when the central portion (4) of the metal plate current collector (1) is joined to the bottom of the battery can by welding, at least a part of the metal plate current collector (1) is closed around the central portion (4). If the annular hole (14) is provided, the annular hole at least part of which is closed at the time of welding the central portion (4) of the metal plate current collector (1) to the bottom of the battery can. Utilizing (14), the central part (4) of the metal plate current collector (1) is raised from other parts, and only the central part (4) is selectively brought into contact with the bottom of the battery can. By welding and joining, the welding efficiency is improved as compared with the case where the entire metal plate current collector (1) including not only the central part (4) but also other parts is brought into contact with the bottom of the battery can and welded. I do. The above-mentioned at least partially closed annular hole (14) may be, for example, a horseshoe-shaped hole, a partially closed annular ring, other than the U-shaped hole as illustrated in the figure. Holes and the like. Of course, an annular hole (14) in which at least a part thereof is closed can also be used for injecting the electrolytic solution. Note that FIG.
In the metal plate current collector (1) shown in (1), one end of the cutout (6) is connected to a part of the annular hole (14) which is at least partially closed.

In the above description, an example was described in which a circular metal plate was used as the metal plate current collector. However, in the present invention, the form of the metal plate current collector is limited to a circular shape. Instead, for example, as shown in FIG. 5, it is of course possible to adopt a substantially square or substantially rectangular shape or a combination of a substantially semicircular shape and a substantially square shape.

As the electrode substrate (10) of the wound electrode group (9) in the present invention, a substrate made of a metal foil, a porous metal or the like is used, and the electrode substrate is welded to the metal plate current collector. In order to prevent a short circuit at the time, in the width direction, the positive electrode and the negative electrode are 0.5 mm or more and 5 mm or less, particularly 1 mm or more and 3 mm or less.
It is preferable to wind in a state shifted in the following range.

In the secondary battery of the present invention, the electrode substrate (10) of the above-mentioned wound electrode group (9) and the metal plate current collector (1) are joined, and this is inserted into a battery can, and After injecting the liquid,
It is manufactured through a process of sealing with a battery lid, an annular gasket, or the like.

The secondary battery to which the metal plate current collector of the present invention can be applied is a cylindrical, elliptical or square cylindrical type using a wound electrode group obtained by winding a positive electrode and a negative electrode via a separator. Alkaline secondary batteries, non-aqueous electrolyte secondary batteries and the like. Among these secondary batteries, secondary batteries used for applications requiring a large current discharge of 10 A or more requiring low internal resistance are required. Particularly useful in batteries.

[0026]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to only these examples.

EXAMPLE 1 A positive electrode composed of a known paste-type nickel electrode (substrate: foamed nickel) having a length of 740 mm and a thickness of 0.25 mm and a known paste-type hydrogen storage alloy electrode having a length of 800 mm and a thickness of 0.15 mm A negative electrode made of (substrate: perforated iron-nickel-plated steel sheet) is wound through a separator having a thickness of 0.1 mm, and a wound electrode group is produced so that the battery can be accommodated in a maximum amount in a battery can having a 24.7 mm inner size. did. As shown in FIG. 3, the positive electrode substrate of this wound electrode group has a metal plate (2) having a bent portion (7) having a length of 5 mm and a width of 0.5 mm from an outer peripheral portion (3) to a central portion ( Central portion (4) having a bent portion (8) of 5 mm in length and 0.5 mm in width as well as three cut portions (5) of 5 mm in length and 3 mm in width toward 4)
A metal plate for a positive electrode having a diameter of 19 mm, having one notch (6) having a length of 5 mm and a width of 3 mm extending from the front to the outer peripheral portion (3), and a tab (12) provided at a substantially central portion (4) thereof. The electric body (1) was joined by welding. That is, the joining of the wound electrode group (9) of the metal plate current collector (1) for the positive electrode to the substrate (10) by welding is performed by the metal plate current collector (1).
At the bent portion (7) of the cut portion (5) and the bent portion (8) of the cut portion (6). In the positive electrode metal plate current collector (1), a tab (12) provided at a substantially central portion (4) of the current collector is welded to a battery lid constituting a positive electrode terminal portion of the battery at the time of assembling the battery. Are joined.

The negative electrode substrate of the wound electrode group may be
As shown in FIG. 4, an outer peripheral portion (3) having a bent portion (7) having a length of 5.5 mm and a width of 0.5 mm on a metal plate (2).
As with the three cuts (5) having a length of 5.5 mm and a width of 3 mm toward the central portion (4), the slits have a length of 5.5 mm and a width of 0.5 mm.
It has one notch (6) having a length of 5.5 mm and a width of 3 mm from a central portion (4) having a bent portion (8) of 5 mm to an outer peripheral portion (3), and the periphery of the central portion (4). Then, a metal plate current collector (1) for a negative electrode having a diameter of 20 mm provided with a U-shaped hole as a hole (14) at least partially closed was joined by welding. That is, the joining of the wound electrode group of the metal plate current collector (1) for the negative electrode to the substrate by welding the negative electrode to the substrate is performed by bending the cut portion (5) of the metal plate current collector (1). ) And the bent portion (8) of the cut portion (6). The central portion (4) of the negative electrode metal plate current collector (1) is joined by welding to the bottom of the battery can constituting the negative electrode terminal portion of the battery during battery assembly.

Welding points and distribution of the positive electrode metal plate current collector (1) and the positive electrode substrate of the wound electrode group, and the negative electrode metal plate current collector (1) and the negative electrode of the wound electrode group The welding point with the substrate and its distribution were measured. In the above measurement, the welded metal plate current collector is peeled off from the electrode substrate, the wound electrode group is unwound, and the length (distance) from the winding center side end of the electrode to each welding point is measured. By doing that.

The tab (12) of the metal plate current collector (1) for the positive electrode has a form as shown in FIG. 3, and its lower leg is formed substantially at the center of the metal plate (2). Is provided by joining with resistance welding. The length of the bent portion (7) of the cut portion (5) and the length of the bent portion (8) of the cut portion (6) of the metal plate current collector (1) for the positive electrode are 5 mm, respectively. The length (L) from the central hole end (11) to the outer peripheral portion (3) in (2) is 9 mm, and the length of the longest portion of the bent portion (7) of the cut portion (5) and the cut portion ( The sum of the length of the bent portion (8) and the length of the longest portion of (6) is 1.11 with respect to the above (L). Further, the ratio of the length of the bent portion (8) of the cut portion (6) to the length of the bent portion (7) of the cut portion (5) is 1.0. The length of the bent portion (7) of the cut portion (5) and the length of the bent portion (8) of the cut portion (6) of the metal plate current collector (1) for the negative electrode are 5.5 mm, respectively. The length (L) from the hole end (11) at the center of the metal plate (2) to the outer periphery (3) is 9.4 mm, and the length of the longest part of the bent part (7) of the cut part (5). The sum of the length of the longest portion of the bent portion (8) of the cut portion (6) is 1.16 with respect to the above (L). Further, the ratio of the length of the bent portion (8) of the cut portion (6) to the length of the bent portion (7) of the cut portion (5) is 1.0.

COMPARATIVE EXAMPLE 1 As shown in FIG. 7, a metal plate (131) having a diameter of 19 mm was replaced by a metal plate (131) having a protruding edge (13) as shown in FIG.
3) A metal plate current collector (130) having 24 circular openings (132) each having a diameter of 2 mm and having a diameter of 2 mm (shown by a thick line) is used, and is replaced with the metal plate current collector for a negative electrode of Example 1. As shown in FIG. 10, a metal plate current collector (130) in which 24 circular openings (132) having a diameter of 2 mm and a protruding edge (133) are formed in a metal plate (131) having a diameter of 20 mm is used. Except for this, the metal plate current collectors (130) were welded to the electrode substrate of the wound electrode group in the same manner as in Example 1, and the welding points and their distributions were measured. The metal plate (131) of the metal plate collector (130) for the positive electrode has a circular hole (135) at the center and a tab (134) at the outer periphery. The metal plate (131) of the metal plate current collector (130) for the negative electrode has a U-shaped hole as an annular hole (136) in which at least a part is closed at the center. Then, the metal plate current collector for positive electrode (130) shown in FIG. 7 and the metal plate current collector shown in FIG. 8 in a state where it is joined to the electrode (positive electrode) substrate (10) of the wound electrode group (9) are joined. In the body (130) and the negative electrode metal plate current collector (130) shown in FIG.
The metal plate (131) is provided with a slit (137). The slit (137) is used when the metal plate current collector (130) is joined to the electrode substrate of the wound electrode group by welding. This is to prevent current from flowing over the entire surface of the metal plate (131) and to facilitate welding.

COMPARATIVE EXAMPLE 2 As shown in FIG. 9, a metal plate (151) having a diameter of 19 mm was replaced with a bent portion (153) having a length of 5 mm and a width of 0.5 mm as shown in FIG. ) (Shown in bold line)
Is provided with only four notches (152) extending from the outer peripheral portion having a length of 5 mm and a width of 3 mm toward the central portion (that is,
There is no cut from the center to the outer periphery.)
Using the metal plate current collector (150) and replacing the negative electrode metal plate current collector of Example 1 with only four notches (152) from the outer peripheral portion toward the central portion as shown in FIG. Except for using the negative electrode metal plate current collector (that is, not having a cut portion extending from the central portion to the outer peripheral portion) (150), the metal plate current collectors (15
0) was welded to the electrode substrate of the wound electrode group, and the welding points and their distribution were measured. Although not shown in FIG. 9, the metal plate current collector (150) for the positive electrode has the same shape as the metal plate current collector (130) used for the positive electrode in Comparative Example 1. 151) has an integrally formed tab on the outer peripheral portion. The metal plate (151) of the metal plate current collector (150) for the positive electrode has a circular hole (155) in the center, and the metal plate (15) of the metal plate current collector (150) for the negative electrode.
1) has a U-shaped hole as an annular hole (156) which is at least partially closed at the center.

FIG. 12 shows the state of welding between the positive electrode metal plate current collectors of Example 1 and Comparative Examples 1 and 2 and the positive electrode substrate from the winding center end of the positive electrode toward the outer periphery. The figure which compared by welding point integration is shown. FIG. 13 shows the state of welding between the negative electrode metal plate current collectors of Example 1 and Comparative Examples 1 and 2 and the negative electrode substrate from the winding center end of the negative electrode toward the outer periphery. The figure which compared by welding point integration is shown. FIG. 12 above
13 and the cumulative number of welding points (pieces) on the vertical axis in FIG. 13 indicates the number of welding points integrated until the length of the electrode on the horizontal axis (length from the end of the electrode on the winding center side) is reached. .

As is clear from the results shown in FIGS. 12 and 13, in Comparative Examples 1 and 2, welding was not performed at the center of the winding (that is, at the inner periphery of the wound electrode group). In addition, in Comparative Example 1, the outer periphery of the winding (that is, the outer periphery of the wound electrode group) was not welded, but in Example 1, the welding was performed at both the center of the winding and the outer periphery of the winding. It can be seen that the welding was sufficiently performed, and that the welding points in Example 1 were more uniformly dispersed in the length direction of the electrode than in Comparative Examples 1 and 2.

[0035]

As described above, according to the present invention, a metal suitable for a large current application capable of collecting current from many points relatively evenly distributed in the length direction of a long electrode. A plate current collector can be provided, and by using the metal plate current collector, a secondary battery suitable for high-current applications can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a metal plate current collector of the present invention (however, before a tab is attached).

FIG. 2 is a perspective view showing an example of a metal plate current collector of the present invention (however, before a tab is attached).

FIG. 3 is a perspective view showing an example of a state in which the metal plate current collector of the present invention is joined to an electrode substrate of a wound electrode group.

FIG. 4 is a plan view showing another example of the metal plate current collector of the present invention.

FIG. 5 is a plan view showing still another example of the metal plate current collector of the present invention (but before the tab is attached).

FIG. 6 is a plan view showing an example of a metal plate current collector (but before a tab is attached) outside the present invention.

FIG. 7 is a plan view showing an example of a conventional metal plate current collector.

FIG. 8 is a perspective view showing an example of a state in which a conventional metal plate current collector is joined to an electrode substrate of a wound electrode group.

FIG. 9 is a plan view showing another example of a conventional metal plate current collector (however, before a tab is attached).

FIG. 10 is a plan view showing still another example of the conventional metal plate current collector.

FIG. 11 is a plan view showing still another example of the conventional metal plate current collector.

FIG. 12 shows the length and the number of welding points of the positive electrode from the center on the winding center side when the positive electrode metal plate collectors of Example 1 and Comparative Examples 1 and 2 are joined to the positive electrode substrate of the wound electrode group. It is a figure which shows the relationship with integration.

FIG. 13 shows the length and the number of welding points of the negative electrode from the end on the winding center side when the negative electrode metal plate current collectors of Example 1 and Comparative Examples 1 and 2 were joined to the negative electrode substrate of the wound electrode group. It is a figure which shows the relationship with integration.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal plate current collector 2 metal plate 3 outer peripheral portion 4 central portion 5 cut portion 6 cut portion 7 bent portion 8 bent portion 9 wound electrode group 10 electrode substrate 11 hole end 12 tab 13 hole 14 at least a part Closed annular hole

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hideto Itano 1-1-88 Ushitora, Ibaraki-shi, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Inventor Masato Isogai 1-188 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell F-term (reference) 5H022 AA04 AA09 AA18 BB02 BB11 CC12 CC13 CC16 CC19 5H028 AA05 BB04 BB05 CC05 CC12 5H029 AJ02 BJ02 BJ14 CJ03 CJ04 DJ05 DJ07 DJ14

Claims (5)

[Claims] An electrode substrate (10) for a wound body electrode group (9).
And a metal plate current collector (1) joined to a terminal portion of the battery, wherein the metal plate current collector (1) moves from the outer peripheral portion (3) of the metal plate (2) toward the central portion (4). It has a plurality of cuts (5) and one cut (6) extending from the central portion (4) of the metal plate (2) to the outer peripheral portion (3), and the cut (5) is a bent portion (7). The notch (6) has a bent portion (8), and a tab (12) is provided at or near the center of the metal plate current collector (1), and the bent portion (7) and the bent Part (8)
The metal plate current collector (1), wherein the metal plate current collector (1) is joined to the electrode substrate (10) of the wound electrode group (9), and is joined to the terminal of the battery by the tab (12). 2. An electrode substrate (10) of a wound body electrode group (9).
And a metal plate current collector (1) joined to a terminal portion of the battery, wherein the metal plate current collector (1) moves from the outer peripheral portion (3) of the metal plate (2) toward the central portion (4). It has a plurality of cuts (5) and one cut (6) extending from the central portion (4) of the metal plate (2) to the outer peripheral portion (3), and the cut (5) is a bent portion (7). An annular hole (14) in which the notch (6) has a bent portion (8) and is at least partially closed around a central portion (4) of the metal plate current collector (1). And a wound electrode group (9) at the bent portion (7) and the bent portion (8).
(1) bonded to the electrode substrate (10) and a metal plate current collector (1)
A metal plate current collector (1), which is joined to a terminal portion of a battery at a central portion (4) of the metal plate current collector. 3. The current collector (1) according to claim 1, wherein the tab (12) is joined to a battery cover constituting a terminal portion of the battery. 4. The metal plate current collector according to claim 2, wherein a central portion of the metal plate current collector is joined to a bottom portion of a battery can forming a terminal portion of the battery. 1). 5. A secondary battery using the metal plate current collector (1) according to claim 1.