KR100578982B1 - Secondary Battery - Google Patents

Abstract

The electrode group in which the positive electrode plate and the negative electrode plate are positioned with the separator interposed therebetween, the case in which the electrode group is embedded, and the case so that the separator is not bent and the separator is not damaged during laser welding even when a part of the separator is exposed. Provided is a secondary battery including a cap assembly coupled to seal the case and electrically connected to an electrode group, and a current collector plate formed of a dissimilar metal and electrically connected to the electrode group.

Secondary Battery, Pole Plate, Plain Part, Separator, Laser, Welding, Clad, Current Collecting Plate

Description

Secondary Battery

1 is a cross-sectional view showing an embodiment of a secondary battery according to the present invention.

2 is a perspective view showing an embodiment of a positive electrode current collector according to the present invention.

3 is a perspective view showing another embodiment of a positive electrode current collector according to the present invention.

4 is a perspective view showing still another embodiment of a positive electrode current collector according to the present invention.

5 is a perspective view showing still another embodiment of a positive electrode current collector according to the present invention.

6 is a cross-sectional view showing another embodiment of a secondary battery according to the present invention.

7 is a perspective view illustrating a negative electrode current collector plate in another embodiment of the secondary battery according to the present invention.

The present invention relates to a secondary battery, and more particularly, the positive electrode current collector plate and / or the negative electrode current collector plate are composed of a plurality of layers of a metal having excellent weldability and a metal having excellent conductivity, and thus the positive electrode plate and / or the negative electrode plate are not uniformly aligned. The present invention also relates to a secondary battery in which a part of the separator exposed during welding is not broken.

In general, a secondary battery is a battery that can be repeatedly used because it can be charged and discharged. A secondary battery composed of one battery cell is mainly used for portable small electronic devices such as mobile phones, notebook computers, cameras, and camcorders. As a power source for driving a motor such as a hybrid vehicle, a large capacity secondary battery formed by connecting a plurality of battery cells is mainly used.

Conventional secondary batteries are formed in various shapes such as cylindrical, square, and pouch types, and a separator group (insulator) is inserted between a strip-shaped positive electrode plate and a negative electrode plate, and spirally wound electrode groups (jelly rolls) are installed in a case. And, it is made by installing a cap assembly having an external terminal formed in the case.

In the above, the positive electrode plate and the negative electrode plate are made by coating an active material on the current collector, respectively, and an uncoated portion having no active material coated is formed at a corner portion. Conductive tabs for collecting current generated in the positive electrode plate and the negative electrode plate are respectively attached to the uncoated portions of the positive electrode plate and the negative electrode plate, and the conductive tabs are connected to external terminals (positive electrode terminal and negative electrode terminal) of the cap assembly. The positive electrode plate and the negative electrode plate and the positive electrode terminal and the negative electrode terminal are respectively made to be electrically connected.

In the current collector structure of the secondary battery configured as described above, in the case of the high output secondary battery, a current collector plate is used instead of the conductive tab in order to reduce the resistance, and the separator in the process of welding the current collector plate to the uncoated parts of the positive electrode plate and the negative electrode plate. There is a problem that is broken. That is, in the conventional case, in order to weld the current collector plate and the uncoated portion, in the electrode group wound in the form of a jelly roll, the uncoated portion forming the corner portion is bent flat so as to be in surface contact with the current collector plate, and laser welding is performed. In this case, the separator is exposed between the uncoated portions, and a phenomenon occurs in which the separator is damaged by a laser having high energy during laser welding.

In particular, in the case of a high-power large-capacity secondary battery for a hybrid electric vehicle (HEV), a collector plate of a plain part and the same metal is used to perform laser welding with the plain part, and the pole plate is very thin. When winding the roll, combing occurs, which often causes the end of the plain portion to be uneven. And even if the flat portion is bent flat in one direction, a portion which is not bent constantly occurs, and the separator is exposed therebetween.

Therefore, when the energy of the laser that melts the current collector plate during welding is applied to the part having only the current collector plate (the part without the solid part), the laser penetrates the current collector plate and melts the exposed separator, which may cause a short circuit.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and even if a portion of the separator is unevenly bent, a plurality of layers of a metal having excellent weldability and a metal having excellent conductivity so as not to break the separator during laser welding, even when a part of the separator is exposed. It is to provide a secondary battery using a current collector plate made of.

The secondary battery proposed by the present invention includes an electrode group in which a positive electrode plate and a negative electrode plate are positioned with a separator interposed therebetween, a case in which the electrode group is embedded, and a case coupled with the case to seal the case and electrically connect the electrode group. And a current collector plate formed of a dissimilar metal and electrically connected to the electrode group.

The current collector plate may be formed of a clad metal including a base layer having any electrical conductivity and an auxiliary layer having a lower melting point than the base layer and disposed closer to the electrode group than the base layer.

The current collector plate may be disposed between the cap assembly and the electrode group to electrically connect the positive electrode plate and the cap assembly, and a negative current collector plate installed between the case and the electrode group to electrically connect the negative plate and the case. Is done.

The positive electrode plate and the negative electrode plate is composed of a coating portion in which the active material is coated on the current collector, and an uncoated portion in which the active material is not coated.

In the above, the uncoated portions of the positive electrode plate and the negative electrode plate are formed to have a predetermined width along one (upper or lower) corner, and the uncoated portion formed on the positive electrode plate and the uncoated portion formed on the negative electrode plate are disposed at opposite edges. Further, in the state in which the cap assembly is assembled to the case by the cap assembly to the upper assembly, the positive plate is formed in the upper corner portion, the negative plate is formed in the lower corner portion.

The positive electrode collector plate or the negative electrode collector plate is electrically connected to the uncoated portion, respectively.

The base layer of the current collector plate is formed of a metal having excellent conductivity such as aluminum or copper. The base layer of the current collector plate may be formed of the same material as the positive electrode plate and / or the negative electrode plate.

The auxiliary layer of the current collector plate is preferably formed of a metal having a lower melting point than the base layer and excellent weldability. Nickel, aluminum, etc. can be used as a metal which is excellent in weldability which forms the said auxiliary layer.

Next, a preferred embodiment of a secondary battery according to the present invention will be described in detail with reference to the accompanying drawings.

First, according to one embodiment of the secondary battery according to the present invention, the electrode group 10 in which the positive electrode plate 11 and the negative electrode plate 12 are positioned with the separator 13 interposed therebetween, and A case 20 having an electrode group 10 embedded therein, a cap assembly 30 coupled to the case 20 to seal the case 20 and electrically connected to the electrode group 10, and the electrode For the positive electrode and the negative electrode for electrically collecting the current generated from the positive electrode plate 11 or the negative electrode plate 12 of the electrode group 10 is electrically connected to the group 10 and the cap assembly 30 or the case 20 Current collector plates 40 and 50.

The positive electrode current collector plate 40 is a clad metal including a base layer 46 formed of a dissimilar metal, that is, a metal having excellent conductivity, and an auxiliary layer 48 formed of a metal having excellent weldability. Is done in a way.

An electrolyte solution is accommodated together with the electrode group 10 in a sealed space formed of the case 20 and the cap assembly 30.

The cap assembly 30 is installed at the upper end of the opening of the case 20 with the gasket 31 interposed therebetween.

The case 20 is formed of a conductive metal such as aluminum, an aluminum alloy, or nickel plated steel, and the shape thereof may be formed in various shapes such as a cylindrical shape, a hexahedral shape, a button shape, and the like.

The cap assembly 30 includes a cap plate 32 having an external terminal 32a and a gasket 31 that insulates the case 20 from the cap plate 32.

In addition, the cap assembly 30 may further include a vent plate 33 that breaks under a set pressure condition and releases gas to prevent explosion of the battery. The vent plate 33 is electrically connected to the positive electrode current collector plate 40 through the lead 35.

The vent plate 33 is not limited to the shape shown in the drawing as long as it can block electrical connection between the electrode group 10 and the external terminal 32a through the lead 35 under a set pressure condition. Can be used.

The electrode group 10 may have a structure in which a positive electrode plate 11 and a negative electrode plate 12 each having a positive electrode active material or a negative electrode active material coated on a current collector are laminated with a separator 13 interposed therebetween, and the positive electrode plate 11 ) And the separator 13 and the negative electrode plate 12 may be formed in a jelly roll-type configuration formed by winding in a spiral shape (vortex shape).

In the present embodiment, as shown in FIG. 1, a configuration in which the jelly roll type electrode group 10 is installed in the cylindrical case 20 will be described as an example.

In the present embodiment, the positive electrode plate 11 and the negative electrode plate 12 in which the uncoated portions 11a and 12a are in electrical contact with the positive electrode current collector plate 40 and the negative electrode current collector plate 50 form the electrode group 10. A structure formed along one corner of the side will be described as an example. Of course, this invention is not limited to the said structure, It is possible to apply all regardless of the shape of a battery or the structure of a plain part.

The electrode group 10 configured as described above includes one positive electrode current collector plate 40 and one negative electrode current collector plate 50 electrically connected to the positive electrode plate 11 and the negative electrode plate 12 to form one electrode assembly.

The current collector plate is provided between the cap assembly 30 and the electrode group 10, the positive electrode current collector plate 40 for electrically connecting the positive electrode plate 11 and the cap assembly 30, and the case 20 And a negative electrode current collector plate 50 provided between the electrode group 10 and electrically connecting the negative electrode plate 12 and the case 20.

The positive electrode plate 11 and the negative electrode plate 12 may be formed of a coating portion in which an active material is coated on a current collector, and non-coating portions 11a and 12a in which an active material is not coated. The positive electrode collector plate 40 or the negative electrode collector plate 50 is electrically connected to the uncoated portions 11a and 12a, respectively.

In the above, the uncoated portions 11a and 12a of the positive electrode plate 11 and the negative electrode plate 12 are formed to have a predetermined width along one (upper or lower) corner, and the uncoated portion 11a is formed on the positive electrode plate 11. ) And the uncoated portion 12a formed on the negative electrode plate 12 are disposed at opposite corners.

That is, in a state in which the case 20 is erected vertically so that the cap assembly 30 faces upward, the non-coated portion 11a which does not apply the positive electrode active material to the current collector at the upper edge portion of the positive electrode plate 11 may face the longitudinal direction. It is formed along, and the non-coated portion (12a) that does not apply the negative electrode active material to the current collector is disposed on the lower edge portion of the negative electrode plate 12 is formed.

The uncoated portion 11a is in electrical contact with the positive electrode current collector plate 40 in a state where the end thereof is bent flat.

The uncoated portion 12a of the negative electrode plate 12 is also in electrical contact with the negative electrode current collector plate 50 or the case 20 in a state where the end is bent flatly (crushed).

It is also possible to contact the plain portion 12a of the negative electrode plate 12 to be electrically connected to the case 20 without using the negative electrode current collector plate 50.

The positive electrode current collector plate 40 is formed with a central hole 41 for injecting an electrolyte or the like in the center portion.

The base layer 46 of the positive electrode current collector plate 40 is made of a metal having excellent conductivity such as aluminum or copper.

In addition, the base layer 46 of the positive electrode current collector plate 40 may be formed of the same material as the positive electrode plate 11.

The auxiliary layer 48 of the positive electrode current collector plate 40 is preferably formed of a metal having a lower melting point than the base layer 46 and excellent weldability.

Nickel, aluminum, or the like may be used as the metal having excellent weldability for forming the auxiliary layer 48. The metal forming the auxiliary layer 48 is also slightly less conductive than the base layer 46, but basically has a metal that is conductive enough to make electrical connection between the uncoated portion 11a and the base layer 46. It is desirable to choose.

When the base layer 46 is formed of copper and the auxiliary layer 48 is formed of nickel, a laser is used to weld the positive electrode current collector plate 40 to the uncoated portion 11a of the positive electrode plate 11. In the case of irradiation, since the melting point of the nickel of the auxiliary layer 48 is lower than that of the copper of the base layer 46, the nickel is melted and welded even when laser energy is applied to the extent that copper is not melted. Therefore, even when the uncoated portion 11a is unevenly bent and a part of the separator 13 is exposed, the base layer 46 is penetrated by the energy of the laser for welding so that the laser is irradiated to the exposed part of the separator 13. It does not happen, and it is possible to prevent damage to the separator 13.

That is, since it is difficult to weld directly with the positive electrode current collector plate 40 in the state in which the uncoated portion 11a of the positive electrode plate 11 is perpendicular to the positive electrode current collector plate 40 while being wound with jelly rolls, the plain part 11a The ends of the flattened bend flat and then welded. In this process, the ends of the plain 11a are not bent uniformly, but are irregularly crushed and bent to separate the separators between the plain 11a and the plain 11a. 13) occurs where it is exposed.

However, even when the exposed portion is located in the laser welding line, the auxiliary layer 48 is placed on the unevenly crushed plain portion 11a as described above, so that a high energy laser is applied to the positive electrode current collector plate 40. Since the auxiliary layer 48 is melted before the 46 is melted, and welding is performed between the uncoated portion 11a and the auxiliary layer 48, sufficient welding is required even if the base layer 46 is not energized. The performance is obtained, and the separator 13 exposed between the uncoated portion 11a and the uncoated portion 11a can be prevented from being damaged by the laser.

In another embodiment of the positive electrode current collector plate 40, as shown in FIG. 3, a plurality of welds 42 are formed radially.

The welding part 42 is formed to protrude toward the electrode group 10 more than other parts (the bottom surface or the bottom surface).

The welding portion 42 is preferably formed so that the end surface protruding so that the laser welding is made smoothly has a plane having a predetermined width.

It is preferable that the said welding part 42 is generally formed in the cross shape corresponding to performing a laser welding in the cross shape.

In the above, the arrangement and the number of the welding portions 42 can be appropriately set according to the method of performing laser welding.

In addition, the positive electrode current collector plate 40 may be formed by protruding the grip portion 45 along the center hole 41 for the worker to hold by hand when handling the component.

The gripping portion 45 may be conveniently used as a welding point in order to improve weldability when welding the lead 35.

In another embodiment of the positive electrode current collector plate 40, as shown in FIG. 4, the auxiliary layer 48 is formed to correspond only to a portion where the weld part 42 is formed.

When the auxiliary layer 48 is formed as described above, the material cost can be reduced, and the overall weight can be reduced.

In another embodiment of the positive electrode current collector plate 40, as shown in FIG. 5, one or more reinforcement parts 49 are formed to reinforce strength, and at least one electrolyte injection hole 43 is formed in addition to the central hole 41. To form more.

The reinforcement 49 may be embodied by partially forming irregularities, and may be embodied by folding corners along a circumference.

The electrolyte injection opening 43 allows smooth electrolyte injection when the electrolyte is injected into the electrode group 10 in the case 20.

Another embodiment of the secondary battery according to the present invention, as shown in Figs. 6 and 7, the base layer 56 for forming the negative electrode current collector plate 50 made of a metal having excellent conductivity similar to the positive electrode current collector plate 40 And a plurality of layers of the auxiliary layer 58 formed of a metal having excellent weldability.

In the negative electrode current collector plate 50, the base layer 56 is formed on the side in contact with the case 20, and the auxiliary layer 58 is formed on the side in contact with the electrode group 10.

Also in the case of the negative electrode current collector plate 50, since it can be implemented in the same configuration as the positive electrode current collector plate 40, the detailed description thereof will be omitted.

The secondary battery according to the present invention configured as described above is a device for operating by using a motor such as a HEV (hybrid electric vehicle), an EV (electric vehicle), a wireless cleaner, an electric bicycle, an electric scooter, etc. It can be used as an energy source (motor drive), and in addition, it can be used for various applications requiring high power / large capacity.

In the above, a preferred embodiment of a secondary battery according to the present invention has been described, but the present invention is not limited thereto, and various modifications can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. This also belongs to the scope of the present invention.

According to the secondary battery according to the present invention made as described above, since the auxiliary layer is melted by the laser energy to the extent that the base layer does not melt when welding the current collector plate and the electrode group, welding is performed, the electrode group by the laser energy It is possible to prevent the short circuit caused by breakage of the separator, and to improve the reliability of the product.

Claims (8)

An electrode group in which the positive electrode plate and the negative electrode plate are positioned with the separator interposed therebetween; A case in which the electrode group is embedded; A cap assembly coupled to the case and sealed and electrically connected to the electrode group; A positive electrode current collector plate formed of a dissimilar metal and disposed between the cap assembly and the electrode group to electrically connect the positive electrode plate and the cap assembly; A negative electrode current collector plate formed of dissimilar metal and installed between the case and the electrode group to electrically connect the negative plate and the case. Secondary battery comprising a. delete The method according to claim 1, The current collector plate, A secondary battery, which is a clad metal comprising a base layer having an arbitrary electrical conductivity and an auxiliary layer having a lower melting point than the base layer and disposed closer to the electrode group than the base layer. The method according to claim 3, The base layer of the current collector plate is formed of aluminum or copper secondary battery. The method according to claim 3, The secondary battery of the current collector plate is formed of nickel. The method according to claim 1, Secondary battery protruding toward the electrode group than the other portion in the current collector plate to form a plurality of welding portions disposed radially. The method according to claim 6, The auxiliary layer is formed to correspond only to the portion where the weld is formed. The method according to claim 1, The secondary battery is a secondary battery for driving a motor.

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