Patent ID: 12257646

MODE FOR CARRYING OUT THE INVENTION

Advantages and features of the present invention, and implementation methods thereof will be clarified through following embodiments described with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Further, the present invention is only defined by scopes of claims. Like reference numerals refer to like elements throughout.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a generally used dictionary are not construed ideally or excessively unless defined apparently and specifically.

In this specification, the terms are used only for explaining embodiments while not limiting the present invention. In this specification, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. The meaning of “comprises” and/or “comprising” used in the specification does not exclude the presence or addition of other components besides a mentioned component.

Hereinafter, preferred embodiments will now be described in detail with reference to the accompanying drawings.

FIG.3is an assembly view of a secondary battery1according to an embodiment of the present invention.

A process of manufacturing the pouch-type secondary battery1according to an embodiment of the present invention is as follows. First, slurry, in which an electrode active material, a binder, and a plasticizer are mixed, is applied to a positive electrode collector and a negative electrode collector to manufacture a positive electrode and a negative electrode. Then, the positive electrode and the negative electrode are stacked on both sides of a separator to form an electrode assembly10having a predetermined shape. Subsequently, the electrode assembly10is inserted into a battery case13, an electrolyte is injected into the battery case13, and the battery case is sealed.

The electrode assembly10includes an electrode tab as illustrated inFIG.3. The electrode tab11is connected to each of the positive electrode and the negative electrode of the electrode assembly10and protrudes outward from the electrode assembly10to serve as a path through which electrons move between the inside and the outside of the electrode assembly10. The collector of the electrode assembly10is provided as a portion which is coated with the electrode active material and an end portion, that is, a non-coating portion which is not coated with the electrode active material. Here, the electrode tab11may be formed by cutting the non-coating portion or formed by connecting a separate conductive member to the non-coating portion through ultrasonic welding or the like. Although the electrode tabs11protrude from one side of the electrode assembly10in parallel to each other in the same direction as illustrated inFIG.3, the embodiment is not limited thereto, and thus, the electrode tabs may respectively protrude in different directions.

An electrode lead12is connected to the electrode tab11of the electrode assembly10through laser welding or the like. Also, a portion of the electrode lead12is surrounded by an insulation part14. The insulation part14is disposed to be limited within a sealing part134on which an upper pouch131and a lower pouch132of the battery case13are thermally bonded to bond the electrode lead12to the battery case13. Also, the insulation part14prevents electricity generated from the electrode assembly10from flowing to the battery case13through the electrode lead12and allows the sealing of the battery case13to be maintained. Thus, the insulation part14is manufactured from a non-conductor having non-conductivity in which the electricity does not flow well. Generally, although relatively thin insulation tape easily attached to the electrode lead12is widely used as the insulation part14, the embodiment is not limited thereto, and thus, various members may be used as long as the members are capable of insulating the electrode lead12.

The electrode leads12may extend in the same direction or may extend in opposite directions, depending on formation positions of a positive tab111and a negative tab112. A positive electrode lead121and a negative electrode lead122may be made of materials different from each other. That is, the positive electrode lead121may be made of the same aluminum (Al) material as a positive electrode plate, and the negative electrode lead122may be made of the same copper (Cu) or nickel (Ni)-coated copper material as a negative electrode plate. Also, a portion of the electrode lead12protruding outward from the battery case13serves as a terminal part and is electrically connected to an external terminal.

In the pouch-type secondary battery1according to embodiments of the present invention, the battery case13is a pouch manufactured from a flexible material. Hereinafter, the battery case13will be described as being the pouch. The battery case13is sealed after accommodating the electrode assembly10so that a portion of the electrode lead12, i.e., the terminal part is exposed. The battery case13includes the upper pouch131and the lower pouch132as illustrated inFIG.3. The lower pouch132is provided with an accommodation space1331that accommodates the electrode assembly10, and the upper pouch131covers the accommodation space1331from an upper side so that the electrode assembly10is not separated to the outside of the battery case13. Here, as illustrated inFIG.3, the accommodation space1331is also provided in the upper pouch131to accommodate the electrode assembly10from the upper side. Although the upper pouch131and the lower pouch132may be manufactured so that one side of each of the upper pouch131and the lower pouch132are connected to each other as illustrated inFIG.3, the embodiment is not limited thereto, and the pouches may be diversely manufactured, for example, individually manufactured by being separated from each other.

When the electrode lead12is connected to the electrode tab11of the electrode assembly10, and the insulation part14is provided on the portion of the electrode lead12, the electrode assembly10is accommodated in the accommodation space1331provided in the lower pouch132, and the upper pouch131covers the accommodation space1331from the upper side. When an electrolyte is injected, and then the sealing part134provided on an edge of each of the upper pouch131and the lower pouch132is sealed, the secondary battery1is prepared.

FIG.4is a schematic view illustrating a state in which ultrasonic welding is performed on the electrode tabs11by the welding device2according to an embodiment of the present invention.

When the plurality of electrode tabs11are ultrasonically welded to each other, first of all, the plurality of electrode tabs11to be welded are seated on the welding surface of an anvil22, and then, as illustrated inFIG.4, a pressure is applied to the electrode tabs11on a welding surface211(seeFIG.5) of a horn21. Here, a plurality of protrusions212(seeFIG.5) are continuously arranged at a certain interval to provide a protrusion formation part213(seeFIG.5) on the welding surface211of the horn21. As the plurality of protrusions212are inserted into the plurality of electrode tabs11, patterns recessed in a shape corresponding to the protrusions212are formed on the outermost surface of the electrode tabs11. Then, when ultrasonic waves having a high frequency of approximate 20 kHz are applied, vibration energy of the horn21and the anvil22is converted into thermal energy due to friction to perform the welding.

Also, laser welding is performed on an electrode tab11, which is provided after the ultrasonic welding is completed, and an electrode lead12. Here, after the electrode tab11and the electrode lead12overlap each other, laser beams having a high energy density are emitted to the electrode tab11and the electrode lead12. Therefore, portions between the electrode tab11and the electrode lead are temporarily melted, and the melted portions are solidified again and then welded.

FIG.5is a schematic view illustrating the welding surface211of the horn21according to an embodiment of the present invention.

When ultrasonic welding is performed by using the welding device2according to an embodiment of the present invention, a plurality of pattern formation parts1131and1132(seeFIG.8) and a pattern-free part1133(seeFIG.8) are formed on the electrode tab11because a protrusion-free part214is provided between the plurality of protrusion formation parts213of the horn21. As the laser welding is performed through the pattern-free part1133, the energy of the laser beams may be prevented from dispersing to improve the welding strength of the laser welding.

For this, the welding device2according to an embodiment of the present invention includes: the horn21including the plurality of protrusion formation parts213, each of which has the plurality of protrusions212that protrude from the welding surface211and are arranged in a line in at least one row, the plurality of protrusion formation parts213respectively forming the pattern formation parts1131and1132on the electrode tab11of the secondary battery1, and the protrusion-free part214which is disposed between the plurality of protrusion formation parts213and in which the protrusions212are not provided to expose the welding surface211to the outside, the protrusion-free part214forming the pattern-free part1133on the electrode tab11, wherein the protrusion-free part214has a width W greater than a width D of each of the protrusions212; the anvil22facing the horn21with the electrode tabs11therebetween to weld the electrode tabs11; and a laser generation part23(seeFIG.8) that generates laser beams to emit the laser beams onto the pattern-free part1133when the electrode tabs11overlaps the electrode lead12.

Also, the horn21according to an embodiment of the present invention includes: the plurality of protrusion formation parts213, each of which has the plurality of protrusions212that protrude from the welding surface211and are arranged in a line in at least one row, the plurality of protrusion formation parts213respectively forming the pattern formation parts1131and1132on the electrode tab11of the secondary battery1; and the protrusion-free part214which is disposed between the plurality of protrusion formation parts213and in which the protrusions212are not provided to expose the welding surface211to the outside, the protrusion-free part214forming the pattern-free part1133on the electrode tab11, wherein the protrusion-free part214has the width W greater than the width D of each of the protrusions212.

As illustrated inFIG.5, the protrusion formation part213is a portion in which the plurality of protrusions212protruding from the welding surface211of the horn21are arranged in a line in at least one row. According to an embodiment of the present invention, the protrusion formation part213is provided in plurality and includes a first protrusion formation part2131and a second protrusion formation part2132as illustrated inFIG.5.

The first protrusion formation part2131is provided on an upper portion of the horn21as illustrated inFIG.5, and the second protrusion formation part2132is provided on a lower portion of the horn21as illustrated inFIG.5. Also, when the ultrasonic welding is performed, the upper portion of the horn21is located more toward the electrode assembly10, and the lower portion of the horn21is located further away from the electrode assembly10. However, when the plurality of electrode tabs11overlap each other, force by which the electrode tabs11are intended to be detached from each other increases closer to the electrode assembly10. Thus, even in an ultrasonic welding area113on which the ultrasonic welding is performed on the electrode tabs11, welding strength has to increase relatively more in an area that is closer to the electrode assembly10. For this, according to an embodiment of the present invention, in the first protrusion formation part2131, the plurality of protrusions212may be arranged in lines in a plurality of rows. For example, as illustrated inFIG.5, in the first protrusion formation part2131, the plurality of protrusions212may be arranged in lines in two rows.

On the other hand, force by which the electrode tabs are intended to be detached from each other decreases further away from the electrode assembly10. Thus, in the second protrusion formation part2132, the protrusions may be arranged in a line in only a single row. However, the embodiment is not limited thereto, and thus, in the second protrusion formation part2132, the plurality of protrusions212may also be arranged in lines in a plurality of rows.

The first protrusion formation part2131and the second protrusion formation part2132are respectively provided on the upper and lower portions as illustrated inFIG.5. Here, when the pressure is applied to the electrode tab11of the secondary battery1by the horn21, the pattern formation parts1131and1132in which patterns are recessed in a shape corresponding to the protrusion formation parts213are provided at a positions corresponding to the protrusion formation parts213. Thus, in the ultrasonic welding area113of the electrode tab11, the first pattern formation part1131in which patterns are recessed in a shape corresponding to the first protrusion formation part2131is provided at a position corresponding to the first protrusion formation part2131. Also, the second pattern formation part1132in which patterns are recessed in a shape corresponding to the second protrusion formation part2132is provided at a position corresponding to the second protrusion formation part2132. As a result, the first pattern formation part1131and the second pattern formation part1132are provided at both ends of the ultrasonic welding region113, respectively. Therefore, minimal welding strength in the ultrasonic welding area113may be ensured.

In the first protrusion formation part2131and the second protrusion formation part2132, the plurality protrusions212may be arranged in parallel to each other. Thus, the first pattern formation part1131and the second pattern formation part1132, which are respectively provided by the first protrusion formation part2131and the second protrusion formation part2132, are also parallel to each other.

The protrusion-free part214is disposed between the plurality of protrusion formation parts213as illustrated inFIG.5, and the protrusions212are not provided to expose the welding surface211to the outside. When the pressure is applied to the electrode tab11of the secondary battery1by the horn21, the pattern-free part1133is formed on the electrode tab11. Also, subsequently, the laser welding is performed after the electrode tab11and the electrode lead12overlap each other. Here, according to an embodiment of the present invention, the laser welding is performed on the electrode tab11through the pattern-free part1133. Accordingly, the energy of the laser beams may be prevented from dispersing to improve the welding strength of laser welding.

When the laser welding is performed, the pattern-free part1133has to have a larger width to a certain extent in order to allow the laser beams to avoid an interference with the patterns. However, when the pattern-free part133has an excessively large width, the welding strength may be reduced. Thus, the width W of the protrusion-free part214of the horn21for providing the pattern-free part1133is greater than the width D of the protrusion212and less than two times the width D of the protrusion212. For example, when the width D of the protrusion212is 1.2 mm, the width W of the protrusion-free part214may be greater than 1.2 mm and less than 2.4 mm, preferably, 1.8 mm to 2.2 mm. Accordingly, while the laser beams avoid the interference with the patterns, the welding strength may be ensured at the same time.

FIG.6is a side view of the horn21according to an embodiment of the present invention.

According to an embodiment of the present invention, as illustrated inFIG.6, each of the protrusions212is provided to protrude from the welding surface211to one side in a protrusion formation part213of the horn21. As a shape of the protrusions212is sharper, the protrusion is more deeply inserted into the electrode tab11. As a result, thermal energy may be concentrated on a tip of the protrusion212to improve the welding strength. Accordingly, according to the related art, the protrusion212has a cone or polygonal pyramid shape, but this shape may damage the electrode tab11.

However, according to an embodiment of the present invention, after the ultrasonic welding is performed between the plurality of electrode tabs11, the laser welding is performed between the electrode tabs11and the electrode lead12. Here, the welding strength between the plurality of electrode tabs11may be significantly improved. Thus, according to an embodiment of the present invention, the protrusion212has a truncated cone or a truncated polygonal pyramid shape in which a top surface T and a bottom surface B are parallel to each other as illustrated inFIG.6, and thus the damage of the electrode tab11may be reduced because the protrusion212is not sharp.

FIG.7is a perspective view of the protrusion212according to an embodiment of the present invention.

Since the protrusion212has a truncated cone or a truncated polygonal pyramid shape, the protrusion212has a top surface T and a bottom surface B, and the top surface T and the bottom surface B are parallel to each other. In order to ensure minimal welding strength in ultrasonic welding as the protrusion212is inserted into the electrode tab11, a surface area of the top surface T of the protrusion212has to be narrowed to a certain extent. Simultaneously, in order to reduce the damage of the electrode tab11as much as possible, a surface area of the top surface T of the protrusion212has to be widened to a certain extent.

Thus, if the protrusion212has a truncated square pyramid shape as illustrated inFIG.7, it is preferable that a length of a side d of the top surface T is half or more that of a side D of the bottom surface B. Particularly, it is more preferable that the length of the side d of the top surface T is ⅔ or more that of the side D of the bottom surface B. For example, when the length of the side D of the bottom surface B of the protrusion212is 1.2 mm, the length of the side d of the top surface T may be 0.5 mm or more, more preferably, 0.8 mm or more. Consequently, the damage of the electrode tab11may be reduced as much as possible. However, it is preferable that the length of the side d of the top surface T is ¾ or less that of the side D of the bottom surface B. Consequently, the minimal welding strength may be ensured.

As described above, on the welding surface211of the horn21, the width W of the protrusion-free part214is greater than the width D of the protrusion212. When the protrusion212has the truncated square pyramid shape, the width D of the protrusion212is equal to the length of the side D of the bottom surface B. Thus, the width W of the protrusion-free part214is greater than the length of the side D of the bottom surface B of the protrusion212. However, the embodiment is not limited thereto, and thus, the width W of the protrusion-free part214may be greater than a diameter of the bottom surface B of the protrusion212because the width D of the protrusion212is the diameter of the bottom surface B when the protrusion212has the truncated cone shape.

Also, when the protrusion312has a polygonal pyramid shape, particularly, a regular polygonal pyramid according to the related art, a specific angle is formed between each of sides on a bottom surface thereof and each of sides on a welding surface as illustrated inFIG.1, and thus regular arrangement with diamond patterns are established. However, according to an embodiment of the present invention, the protrusion-free part214is provided between the first protrusion formation part2131and the second protrusion formation part2132. Also, the protrusion-free part214has to have a larger width to a certain extent. Thus, if the protrusion212has the truncated square pyramid shape as illustrated inFIG.7, the side D of the bottom surface B of the protrusion212is disposed in parallel to the side of the welding surface211as illustrated inFIG.5. That is, the protrusions212may be regularly arranged in in the form of a checkerboard. Accordingly, the larger width W of the protrusion-free part214may be ensured, in the limited ultrasonic welding region113, to thereby improve space efficiency, when compared to the arrangement with diamond patterns.

FIG.8is a schematic view illustrating a state in which the laser welding is performed on the electrode tab11and the electrode lead12by the welding device2according to an embodiment of the present invention.

When the ultrasonic welding for the plurality of electrode tabs11are completed by using the horn21and anvil22, the laser welding is performed by using the laser generation part23as illustrated inFIG.8.

When the electrode lead12overlaps the ultrasonically welded electrode tabs11, the laser generation part23generates the laser beams to emit the laser beams onto a portion on which the electrode tabs11and the electrode lead12overlap each other. Particularly, according to an embodiment of the present invention, the laser generation part23emits the laser beams onto the pattern-free part1133as illustrated inFIG.8. Accordingly, the energy of the laser beams may be prevented from dispersing to improve the welding strength of the laser welding.

FIG.9is a schematic view illustrating a welding surface211aof a horn21aaccording to another embodiment of the present invention.

According to an embodiment of the present invention, the protrusion formation part213includes the first protrusion formation part2131and the second protrusion formation part2132, and the protrusion-free part214is provided between the first protrusion formation part2131and the second protrusion formation part2132. If the secondary battery1increases in size, a surface area of the electrode tab11may be widened. In this case, it is preferable that a surface area of the ultrasonic welding area113is also widened to a certain extent. However, if only one protrusion-free part214is provided, the surface area of the ultrasonic welding area113may not be widened, or only the protrusion formation part213may be excessively widened so as to increase in surface area of the ultrasonic welding area113.

Thus, according to another embodiment of the present invention, a protrusion formation part213ahas three or more protrusion formation parts, and a protrusion-free part214ahas two or more protrusion-free parts. For example, the protrusion formation part213amay further include a third protrusion formation part2133aas illustrated inFIG.9. According to another embodiment of the present invention, since the protrusion formation part213ahas the three or more protrusion formation parts, the number of pattern formation parts (not shown) may correspond to that of protrusion formation parts.

In the third protrusion formation part2133a, the plurality of protrusions212are also arranged in a line in at least one row. Also, as illustrated inFIG.9, a first protrusion formation part2131amay be provided on an upper portion of a horn21a, a second protrusion formation part2132amay be provided on a central portion of the horn21a, and the third protrusion formation part2133amay be a lower portion of the horn21a. Thus, in an ultrasonic welding area113, the third pattern formation part (not shown) in which patterns are recessed in a shape corresponding to the third protrusion formation part2133amay be further provided at a position corresponding to the third protrusion formation part2133a.

As described above, in the first protrusion formation part2131a, the plurality of protrusions212may be arranged parallel to the second protrusion formation part2132a. Also, as illustrated inFIG.9, in the third protrusion formation part2133a, the plurality of protrusions212may also be arranged parallel to the second protrusion formation part2132a. Thus, the first to third pattern formation parts (not shown) may be provided parallel to each other.

The protrusion-free part214amay be disposed between the plurality of the protrusion formation parts213a. Thus, as illustrated inFIG.9, the protrusion-free part214amay include a first protrusion-free part2141aprovided between the first protrusion formation part2131aand the second protrusion formation part2132a, and a second protrusion-free part2142aprovided between the second protrusion formation part2132aand the third protrusion formation part2133a. Thus, when a pressure is applied to the electrode tab11of the secondary battery1by the horn21a, a first pattern-free part (not shown) is formed on the electrode tab11by the first protrusion-free part2141a, and a second pattern-free part (not shown) is formed on the electrode tab11by the second protrusion-free part2142a. In addition, when laser welding is performed subsequently after the electrode tab11and the electrode lead12overlap each other, the laser welding is performed on the electrode tab11through the first pattern-free part (not shown) and the second pattern-free part (not shown). Consequently, since the surface area on which the laser welding is performed increases, the welding strength of the laser welding may be further improved.

Also, each of both a width W1of the first protrusion-free part2141aand a width W2of the second protrusion-free part2142amay be greater than the width D of the protrusion212and less than two times the width D of the protrusion212. Accordingly, while the laser beams avoid the interference with the patterns, the welding strength may be ensured at the same time.

Those with ordinary skill in the technical field to which the present invention pertains will understand that the present invention may be carried out in other specific forms without changing the technical idea or essential features. Thus, the above-described embodiments are to be considered illustrative and not restrictive to all aspects. The scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein. Various modifications made within the meaning and scope of claims and equivalent concepts of the claims are included in the scope of the present invention.