JP2008159357A - Cylindrical secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical secondary battery wherein the contact area of the welding projection of a collector housed in the secondary battery is increased although it is inexpensively structured so as to only make a simple shape change, welding strength of a battery case and the collector is improved, and vibration resistance and impact resistance are strengthened, and electric resistance can be reduced. <P>SOLUTION: A group of electrodes 5 formed by spirally winding a belt-like positive electrode plate 1 and a belt like negative electrode plate 2 with a separator 5 interposed between them are housed in the bottomed cylindrical battery case 9 through the collector 8, and the linear welding projection 14 having a straight line shape or a curved shape, which is in the shape of a projecting part, and the outer surface of which is formed by a plane, is provided in the collector 8 bonded to the bottom part in the battery case 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a current collector suitable as a connection structure for electrically connecting a current collector joined to a lower end of a group of electrode plates wound in a spiral shape in a cylindrical storage battery and an inner surface of a battery case. The present invention relates to the cylindrical secondary battery used.

  Alkaline storage batteries such as nickel-cadmium storage batteries and nickel-metal hydride storage batteries represented by cylindrical secondary batteries are highly reliable and easy to maintain, so they can be used as power sources for portable electronic devices such as mobile phones and laptop computers. Widely used. Furthermore, in recent years, there has been an increasing demand for alkaline storage batteries suitable for large current discharge as power sources for electric tools and electric vehicles.

  As shown in FIG. 6, the alkaline storage battery used for the above-described large current discharge uses a strip-like positive electrode plate 81 and a negative electrode plate 82 with a separator 83 interposed therebetween, and the upper end or lower end of each is a spiral electrode. It winds so that it may protrude from the upper and lower sides of the board group 84, respectively, and is accommodated in metal battery case 89 with electrolyte solution (not shown), and it has the structure which seals the opening part of battery case 89 with the sealing body 85. FIG. .

  In the electrode plate group 84, current collectors 86 and 87 are welded to the tip portions of the positive electrode plate 81 and the negative electrode plate 82 projecting from the upper and lower sides, thereby improving the current collecting performance from the electrode plate group 85 and collecting the current collector. There has been proposed a method in which a projection 88a is provided to stabilize the welding strength by being electrically connected to the battery case 89 via the bodies 86 and 87 and the projection 88a for welding is projected (for example, Patent Document 1). reference).

Further, as shown in FIG. 7, in order to improve the strength and reduce the resistance, not only the welding projection 97 provided in the central portion of the current collector 96 but also the outer periphery of the welding projection 97 in the central portion is arranged. In addition, a method has been proposed in which a welding projection 98 is projected and multi-point welded is welded to a battery case 95 (see, for example, Patent Document 2).
JP 2000-106165 A JP 2005-1000094 A

  However, in the prior art disclosed in Patent Document 1 described above, resistance welding is performed via the point-shaped welding projection 88a shown in FIG. 6 and the battery case 89 is joined, but the force (twisting force) in the rotating direction due to the twist on the battery assembly. Insufficient durability when subjected to vibrations, shocks, etc., especially because strength in the direction of rotation cannot be secured. However, there is a problem that heat is generated when a large current is passed, and electrical resistance increases.

  Further, in the prior art of Patent Document 2, the strength is improved by welding a plurality of projections 97 and 98 shown in FIG. 7, but due to the problem that sufficient pressure is not applied to the projection 98, the electrical resistance due to the connection portion is reduced. Can not contribute, and the welding strength becomes unstable and the battery case 95 is perforated during welding.

The present invention has been made in view of the above-described conventional problems, and is used for linear welding in which a current collector that is joined to a bottom portion in a battery case has a convex outer surface formed by a surface and has a linear shape or a curved shape. With the provision of a projection, it is possible to secure a large contact area with a single projection while maintaining an inexpensive configuration that requires only simple shape changes, and to improve the welding strength of the battery case and the current collector. An object of the present invention is to provide a cylindrical secondary battery that can reliably improve the welding strength in the rotating direction of the plate group and reduce the electrical resistance due to the connection.

  In order to achieve the above object, the present invention has an electrode plate group in which a strip-shaped positive electrode plate and a negative electrode plate are wound in a spiral shape with a separator interposed therebetween, and a current collector is interposed. A cylindrical secondary battery which is housed in a bottom cylindrical metal battery case and the upper end opening of the battery case is sealed with a sealing body via an insulating gasket, and is joined to the bottom of the battery case. The current collector is characterized in that an outer surface having a convex shape is formed by a surface and a linear welding projection having a linear shape or a curved shape is provided.

  According to the present invention, the current collector to be joined to the bottom in the battery case is provided with a linear welding or projection having a linear shape or a curved shape with a convex outer surface formed by a surface. Compared with the conventional spot-shaped welding projection, the contact and welding area can be increased, so that high welding strength can be obtained, and durability when a force such as large vibration, impact or twist is applied. It can be secured sufficiently.

  In addition, since the length of the projection for linear welding is long, it is possible to reliably perform welding even when there is misalignment of the current collector, misalignment of the welding electrode rod, etc. The projection and the bottom of the battery case can be contacted and welding can be performed. In addition, an increase in the welding area enables a reduction in electrical resistance and an improvement in battery characteristics.

  In the first invention of the present invention, the electrode plate group formed by winding the belt-like positive electrode plate and the negative electrode plate in a spiral shape with a separator interposed therebetween has a bottomed cylindrical shape with a current collector interposed therebetween. A cylindrical secondary battery that is housed in a metal battery case and the upper end opening of the battery case is sealed with a sealing body via an insulating gasket, and is a current collector that is joined to the bottom of the battery case. Protruding outer surface is formed by a surface, and linear welding or curved welding projections are provided, so that contact and welding area are large, high welding strength can be obtained, twisting, etc. It is possible to sufficiently ensure durability when a force such as a rotational force, a large vibration, or an impact is applied. Further, the increase in the contact area makes it possible to reduce the electric resistance and improve the battery characteristics.

  In the second invention of the present invention, the flat portion of the current collector is provided with an opening, and a burring protrusion piece formed by bending in the vertical direction adjacent to the opening is formed, and the direction in which the burring protrusion piece is formed Since the projection for linear welding with the convex part formed in the opposite direction is provided in the central part of the current collector, the position deviation of the welding electrode rod due to misalignment of the current collector, misalignment of the welding electrode rod, etc. Even in the case of occurrence of welding, the welding projection can be reliably brought into contact with the bottom portion in the battery case, thereby enabling welding.

  In the third invention of the present invention, the apex of the convex part of the projection for linear welding provided in the central part of the current collector has an R shape, so that the pressing force for pressing the current collector against the battery case is increased. Despite some variations, high welding strength can be obtained, and sufficient durability can be ensured even when a rotational force such as a twist is applied to the electrode plate group.

  According to the fourth aspect of the present invention, since the current collector is formed of pure nickel or iron plated with nickel in a plate shape, it is possible to suppress the current collector from being corroded by the electrolytic solution.

  According to a fifth aspect of the present invention, the current collector is reliably positioned when the current collector is welded to the electrode plate group by providing at least one linear portion on the outer peripheral portion of the current collector. The center of the current collector and the center of the electrode plate group coincide with each other to enable bonding.

  In the sixth aspect of the present invention, the length in the long side direction is longer than the outer diameter of the welding electrode rod used when welding to the bottom of the bottomed cylindrical battery case, and the welding electrode rod By providing the current collector with a linear welding projection whose length in the short side direction is shorter than the outer diameter, when the welding electrode rod is inserted into the central hole of the electrode plate group and resistance welding is performed, the welding electrode rod It is possible to alleviate problems caused by misalignment and to perform reliable resistance welding.

  In the seventh aspect of the present invention, the contact area between the battery case and the current collector is increased by configuring the long-side direction of the linear welding projection provided on the current collector in a radial direction. Stable resistance welding is possible. Moreover, it can simplify processing the shape of the projection for linear welding.

  In the eighth invention of the present invention, the shape of the projection for linear welding provided on the current collector is configured in a cross-shaped shape, so that it is possible to simplify processing and shaping the shape of the projection for linear welding, The battery case and the current collector can be stably disposed, and reliable resistance welding is possible.

  In the ninth aspect of the present invention, the shape of the linear welding projection provided on the current collector is configured in three radial shapes, so that the current collector can be arranged in the battery case without tilting. By increasing the contact area with the battery case, it is possible to reduce electrical resistance by connection.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an alkaline storage battery represented by a cylindrical secondary battery according to an embodiment of the present invention. In this embodiment, one strip-shaped positive electrode plate 1 and negative electrode plate 2 are provided. The electrode plate group 5 wound in a spiral shape with the separator 6 for isolation interposed therebetween is housed in a metal battery case 9.

  Furthermore, as an input / output current collecting structure from the electrode plate group 5 suitable for a large current, the tip end portion 3 of the positive electrode core member protrudes upward from the upper and lower end surfaces of the electrode plate group 5, and the tip end portion 4 of the negative electrode core member moves downward. And a rectangular positive electrode current collector 7 and a negative electrode current collector 8 are welded to a tip portion of the negative electrode current collector 8 at a plurality of locations. The battery case 9 and the negative electrode current collector 8 are linearly connected to the central portion of the negative electrode current collector 8. A linear welding projection 14 is provided, and resistance welding is performed on the center of the bottom of the battery case 9. Then, a positive electrode current collector 7 and a sealing body 11 having an insulating gasket 15 are connected to a peripheral portion having a cap 12 that also serves as a positive electrode terminal incorporating a safety valve 13 by a positive electrode lead 10, and a battery case is connected via the sealing body 11. The opening of 9 is caulked and sealed.

  As shown in FIG. 2, the negative electrode current collector is formed with a linear welding projection 14 having a convex outer surface formed by a surface for electrically connecting the negative electrode current collector 8 and the battery case. What is used as the electric body 8 is illustrated. An opening 16 is provided in the flat portion of the negative electrode current collector 8, and a burring projection piece 17 bent in the vertical direction is provided next to the opening 16. The burring protrusion 17 is resistance-welded to the tip of the negative electrode core member of the electrode plate group, and the linear welding projection 14 having a convex portion in the direction opposite to the direction of the burring protrusion 17 is the central portion of the negative electrode current collector 8. Is provided.

The negative electrode current collector 8 is made of pure nickel or nickel-plated iron and has a plate shape having a thickness of 0.4 mm. The overall shape of the negative electrode current collector when viewed in plan is substantially square. 8
When the electrode plate group 5 is welded, positioning is performed by the linear portion 18 provided on the outer periphery of the negative electrode current collector 8, and resistance welding is performed by matching the center of the electrode plate group 5 with the center of the negative electrode current collector 8. Is going. The thickness of the negative electrode current collector 8 is preferably set within a range of 0.2 to 0.5 mm, and the projection 14 for linear welding when performing resistance welding is a linear type, so that it is completely Even if it is not melted, the electrical resistance at the welded portion does not increase, and a sufficient joined state can be obtained.

  FIG. 4A shows a negative electrode current collector 8 having a linear welding projection 14 formed in a cross-shaped shape in which the long side direction of the linear welding projection 14 is directed in the radial direction. The contact area is further increased, and stable resistance welding is possible. Further, as shown in FIG. 4 (b), the battery case and the negative electrode current collector 8 are stabilized by the linear welding projection 14 in which the long side direction of the linear welding projection 14 is formed in a radial shape in three directions. It can be placed and reliable resistance welding is possible. Further, the negative electrode current collector 8 shown in FIG. 4C has a linear welding projection 14 at the center formed in a curved shape, and has a large contact area despite the small projection of the welding projection. It has a shape that can be secured.

  The negative electrode current collector 8 according to the above embodiment is formed by subjecting the plate material having a predetermined thickness to the drawing process to form the linear welding projection 14 and then opening portions as shown in FIGS. 16 and the burring projection piece 17 can be easily manufactured through a process of punching into a planar shape at the same time. Furthermore, regarding the production of a current collector alone, it is difficult to form a large number of spot-shaped welding projections within a limited area, but a welding projection having a linear shape is a diaphragm that uses a required mold. It can be easily formed by machining, and compared with a current collector provided with a large number of conventional point-shaped welding projections, the management of the mold becomes easier and the life of the mold can be secured longer. With respect to the welding apparatus, there is an advantage that the current collector can be joined to the bottom of the battery case by the number of times of welding with the conventional apparatus.

  As shown in FIG. 1, a separator 6 for separation is interposed between the strip-like positive electrode plate 1 and negative electrode plate 2 one by one, and the tip 3 of the positive electrode core member protrudes from the upper end surface of the electrode plate group 5. The electrode plate group 5 wound in a spiral shape is formed so that the tip portion 4 of the negative electrode core member protrudes from the lower end surface of the plate group 5. Next, the straight line portion 18 at the peripheral edge of the negative electrode current collector 8 having a thickness of 0.4 mm shown in FIG. 2 is positioned, and the center of the electrode plate group 5 and the center of the negative electrode current collector 8 are made to coincide with each other. The piece 17 is resistance-welded to the tip 4 of the negative electrode core.

  Further, the electrode plate group 5 to which the negative electrode current collector 8 is resistance-welded is housed in the battery case 9. Thereafter, as shown in FIG. 3, the battery case 9 containing the electrode plate group 5 is placed on the resistance welding base 21, and the resistance welding electrode rod is inserted into the central hole 19 of the electrode plate group 5 from the opening of the battery case 9. A battery case 9 in which 20 was inserted and resistance welding was performed on the linear projection 14 and the bottom surface of the battery case 9 was taken as Example 1.

(Comparative Example 1)
Using the same electrode plate group and battery case as in Example 1, the negative electrode current collector 87 shown in FIG. 6 was resistance-welded to the electrode plate group 84 and then housed in the battery case 89, and the central portion of the negative electrode current collector 87 was The battery case 89 in which the negative electrode current collector 87 was resistance-welded to the bottom surface of the battery case 89 via the welding projection 88a at the tip of the projection 88 provided on the battery case 89 and the electrode plate group 84 was housed was designated as Comparative Example 1. .

  In order to compare Example 1 and Comparative Example 1 above, the electrode plates in the battery cases of Example 1 and Comparative Example 1 prepared for each of the 20 samples were rotated, and the negative electrode current collector and the battery case were measured as twist strength. Table 1 shows the average value obtained by measuring the strength of the joint and the average value obtained by measuring the tensile strength of the joint between the negative electrode current collector and the battery case by pulling the electrode plate group in the battery case.

（表１）に示されるようにひねり強度および引張り強度に対して大きな違いが明確になった。実施例１の方が比較例１に比べひねり強度および引張り強度とも上回っており、溶接用プロジェクションを点より線状にすることで電池ケース内の底面と集電体の溶接用プロジェクションの溶接面積を増大させることで安定した抵抗溶接ができる上、位置決めできる集電体を極板群の中心に配置して集電体と極板群を溶接することで、抵抗溶接の際に極板群の中心孔に挿入した電極棒で集電体の中心と電池ケースの中心が溶接でき、極板群にひねりの力を加えた場合においても溶接部が中心のため中心から離れた溶接部より回転トルクとしての大きな力が加わることがなく溶接部の強度が大きいと考えられる。

As shown in (Table 1), a great difference was clarified with respect to twist strength and tensile strength. The twist strength and tensile strength of Example 1 are higher than those of Comparative Example 1, and the welding area of the bottom surface in the battery case and the current collector welding projection is increased by making the welding projection linear from the point. By increasing the resistance, stable resistance welding can be performed, and a current collector that can be positioned is placed at the center of the electrode plate group, and the current collector and the electrode plate group are welded, so that the center of the electrode plate group can be obtained during resistance welding. The center of the current collector and the center of the battery case can be welded with the electrode rod inserted into the hole, and even when a twisting force is applied to the electrode plate group, the weld is at the center, so the rotational torque is greater than the weld away from the center. It is considered that the strength of the welded portion is high without applying a large force.

  Furthermore, since the contact area with the bottom in the battery case is increased by the projection for linear welding, some positional deviation can be mitigated, for example, the deviation between the center of the current collector and the electrode plate group and the electrode rod for resistance welding. It is considered that the misalignment of the weld due to the positioning failure was alleviated, and because stable resistance welding was possible, the tensile strength was high and high welding strength was obtained.

  The negative electrode current collector 8 having a different length of the linear welding projection 14 formed on the negative electrode current collector 8 is prepared on the same electrode plate group 5 as in Example 1, and the linear welding projection having the different length is prepared. The electrode plate group 5 in which the negative electrode current collector 8 provided with the resistance 14 is resistance-welded is housed in the battery case 9, and the battery case 8 in which the negative electrode current collector 8 and the bottom surface in the battery case 9 are resistance-welded is defined as Example 2. .

(Comparative Example 2)
Negative electrode current collectors 87 having different numbers of welding projections 88 a formed on the negative electrode current collector 87 are prepared on the same electrode plate group 84 as in Comparative Example 1, and the negative electrode current collectors provided with the different number of welding projections 88 are provided. The electrode plate group 84 resistance welded to the electric body 87 was housed in the battery case 89, and the battery case 89 in which the negative electrode current collector 87 and the bottom surface of the battery case 89 were resistance welded was used as Comparative Example 2.

  In order to compare Example 2 and Comparative Example 2 above, the results of measuring the electrical resistance values of Example 2 and Comparative Example 2 prepared for each of the five are shown in FIG. As shown in FIG. 5, in order to increase the welding strength, the number of spot-shaped welding projections was increased as in Comparative Example 2, but the electrical resistance value due to the connection was hardly changed. In the case of Example 2, by increasing the length of the projection for linear welding in order to increase the welding strength, the contact area with the battery case was increased and the electrical resistance value was reduced.

  In Comparative Example 2, since the contact in the battery case is a point, the electrical resistance value cannot be reduced, the point contact is insufficient, and all points cannot be stably contacted. It is done. Further, it is difficult to form a large number of spot-shaped welding projections within a limited area, and it is difficult to press all points evenly against the bottom of the battery case.

  Based on the above results, the current collector joined to the bottom of the battery case of the present invention is provided with a linear welding or projection having a linear or curved shape with a convex outer surface formed by a surface. The cylindrical secondary battery can provide high welding strength and sufficiently ensure durability when a rotational force such as a twist or a force such as a large vibration or impact is applied. Further, the increase in the contact area makes it possible to reduce the electric resistance and improve the battery characteristics.

Furthermore, even when the current collector is misaligned or the resistance welding electrode rod is misaligned during resistance welding, the resistance welding can be mitigated and surely performed. In addition, there is no difficulty in forming a large number of spot welds in a limited area for the production of a current collector, and a projection for linear welding can be easily formed by drawing using a required mold. This makes it easy to manage the mold and to ensure a long life of the mold.

  According to the present invention, a current collector that is joined to a bottom portion in a battery case is provided with a linear welding or projection having a linear shape or a curved shape with a convex outer surface formed by a surface. The cylindrical secondary battery that contains the electric body can reduce the internal resistance when functioning as a battery, and even when a large current flows, the voltage drop at the junction is small and the operating voltage as a secondary battery Therefore, a large current can be input and output. In addition, the battery characteristics are not varied, and the current collector is made of pure nickel or nickel-plated iron, so that it is not corroded by the electrolytic solution. In addition, it is difficult to form a large number of spot welds in a limited area in a conventional spot-shaped welding projection, but the current collector of the present invention requires a welding projection because it has a linear shape. Therefore, there is an advantage that the die can be easily managed and the life of the die can be secured for a long time. Further, this current collector has an advantage that it can be joined to the current collector and the battery case by the number of times of conventional welding.

1 is a schematic longitudinal sectional view of a cylindrical alkaline storage battery according to an embodiment of the present invention. The perspective view which shows the electrical power collector which concerns on one embodiment of this invention Schematic diagram during resistance welding according to one embodiment of the present invention (A) Perspective view of current collector according to one embodiment of the present invention, (b) Plan view of current collector according to one embodiment of the present invention, (c) Another embodiment of the present invention Plan view of the current collector The characteristic view which shows the electrical resistance value which concerns on one embodiment of this invention Cross-sectional schematic diagram of a cylindrical secondary battery in a conventional example Cross-sectional schematic diagram of a cylindrical secondary battery in another conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Tip part of positive electrode core material 4 Tip part of negative electrode core material 5 Electrode plate group 6 Separator 7 Positive electrode current collector 8 Negative electrode current collector 9 Battery case 10 Positive electrode lead 11 Sealing body 12 Cap 13 Safety valve 14 Projection for linear welding 15 Insulating gasket 16 Opening portion 17 Burring protrusion 18 Linear portion 19 Center hole 20 Electrode rod for resistance welding 21 Resistance welding base

Claims (9)

  An electrode plate group formed by winding a strip-shaped positive electrode plate and a negative electrode plate in a spiral shape with a separator interposed therebetween is housed in a bottomed cylindrical metal battery case with a current collector interposed therebetween, A cylindrical secondary battery in which an upper end opening of the battery case is hermetically sealed with a sealing body via an insulating gasket, and an outer surface having a convex shape on the current collector joined to a bottom of the battery case A cylindrical secondary battery characterized in that a linear welding or projection having a linear shape or a curved shape is provided.   The flat portion of the current collector is provided with an opening, and a burring protrusion piece formed by bending in the vertical direction adjacent to the opening is formed, and a protrusion is formed in a direction opposite to the direction in which the burring protrusion piece is formed. The cylindrical secondary battery according to claim 1, wherein a projection for linear welding is provided at a central portion of the current collector.   3. The cylindrical secondary battery according to claim 2, wherein an apex of a convex portion of a linear welding projection provided at a central portion of the current collector has an R shape.   The cylindrical secondary battery according to claim 1, wherein the current collector is formed of pure nickel or nickel-plated iron in a plate shape.   The cylindrical secondary battery according to claim 1, wherein at least one linear portion is provided on an outer peripheral portion of the current collector.   The length in the long side direction is longer than the outer diameter of the welding electrode rod used when welding to the bottom of the bottomed cylindrical battery case, and the length in the short side direction from the outer diameter of the welding electrode rod The cylindrical secondary battery according to claim 1, wherein the current collector is provided with a linear welding projection having a narrow linear shape.   The cylindrical secondary battery according to claim 5, wherein a long-side direction of the linear welding projection provided in the current collector is configured in a radial direction.   The cylindrical secondary battery according to claim 7, wherein a shape of the linear welding projection provided on the current collector is a cross shape.   The cylindrical secondary battery according to claim 7, wherein a shape of the linear welding projection provided in the current collector is configured in three radial shapes.

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