Folding device for manufacturing electrode assembly and method for manufacturing stack/folding type electrode assembly

Abstract

The present disclosure provides a folding device for manufacturing an electrode assembly having a structure in which plate type unit cells are wound with a separator film, including: a mandrel configured to rotate and wind a web in which plate type unit cells are arranged on an upper surface of the separator film at predetermined intervals so that the unit cells are sequentially stacked with the separator film interposed therebetween; and a pair of rollers configured to horizontally bend a surplus winding end portion of the separator film, which is formed by arranging a first unit cell at a winding start portion of the web in a state of being spaced apart from a winding end portion of the separator film, in a direction covering an upper surface of the first unit cell,
wherein the mandrel includes one or more grippers composed of one or more upper legs configured to fix an upper surface portion of the first unit cell and one or more lower legs configured to fix a lower surface portion of the separator film corresponding to the upper legs, and the pair of rollers operate to vertically bend the surplus winding end portion of the separator film upward and then horizontally bend the surplus winding end portion toward the upper surface of the unit cell.

Claims

1. A folding device for manufacturing an electrode assembly having a structure in which plate type unit cells are wound with a separator film, comprising: a mandrel configured to rotate and wind a web in which plate type unit cells are arranged on an upper surface of the separator film at predetermined intervals so that the unit cells are sequentially stacked with the separator film interposed therebetween; and a pair of rollers configured to horizontally bend a surplus winding end portion of the separator film, which is formed by arranging a first unit cell at a winding start portion of the web in a state of being spaced apart from a winding end portion of the separator film, in a direction covering an upper surface of the first unit cell, wherein the mandrel includes one or more grippers composed of one or more upper legs configured to fix an upper surface portion of the first unit cell and one or more lower legs configured to fix a lower surface portion of the separator film corresponding to the upper legs, and the pair of rollers operate to vertically bend the surplus winding end portion of the separator film upward and then horizontally bend the surplus winding end portion toward the upper surface of the unit cell.

2. The device of claim 1, wherein the pair of rollers is configured to operate independently of each other, or to operate in conjunction with each other.

3. The device of claim 1, wherein the pair of rollers includes a first roller located at a relatively upper portion and a second roller located at a relatively lower portion in a process of horizontally bending the surplus winding end portion.

4. The device of claim 3, wherein the first roller and the second roller move upward to vertically bend the surplus winding end portion upward in a state of being positioned close to a boundary between the first unit cell and the surplus winding end portion of the separator film at a lower portion of the separator film, and move in a direction of the first unit cell to horizontally bend the vertically bent surplus winding end portion in a direction of the upper surface of the first unit cell, so that the surplus winding end portion of the separator film is folded inward in the direction of covering the upper surface of the first unit cell.

5. The device of claim 4, wherein the first roller and the second roller allow the web to be interposed therebetween after the surplus winding end portion is horizontally bent, and then the first roller is moved downward and the second roller is moved upward, thereby performing a process of pressing the horizontally bent surplus winding end portion on the first unit cell.

6. The device of claim 1, wherein a length of the surplus winding end portion of the separator film in the web is 5% to 100% of a width of the first unit cell.

7. The device of claim 1, wherein the upper leg of the gripper fixes the first unit cell together with the horizontally bent surplus winding end portion of the separator film.

8. A method of manufacturing a stacked/folded type electrode assembly by using the folding device of claim 1, comprising: (a) manufacturing a plurality of unit cells including a positive electrode, a negative electrode, and a separator, and arranging the unit cells on a separator film in a long sheet form to manufacture a web; (b) vertically bending a surplus winding end portion by moving upward a pair of rollers located on a boundary between the surplus winding end portion of the separator film and a first unit cell of a winding start portion, which is arranged in a state of being spaced apart from a winding end portion of the separator film in the web, and moving the pair of rollers in a direction of the first unit cell to horizontally bend the surplus winding end portion; (c) pressing the horizontally bent surplus winding end portion of the separator film on the first unit cell after interposing the web between the pair of rollers; and (d) winding by rotating a mandrel so that the unit cells are sequentially stacked with the separator film interposed therebetween.

9. The method of claim 8, wherein the pair of rollers includes a first roller located at a relatively upper portion and a second roller located at a relatively lower portion in a process of horizontally bending the surplus winding end portion.

10. The method of claim 9, wherein the pressing process of process (c) is performed by moving the first roller downward and the second roller upward.

11. The method of claim 8, wherein the mandrel includes a gripper composed of at least one upper leg configured to fix an upper surface portion of the first unit cell and the separator film in which the surplus winding end portion is horizontally bent and at least one lower leg configured to fix a lower surface portion of the separator film corresponding to the upper leg.

12. The method of claim 8, wherein the first unit cell and a second unit cell among the plurality of unit cells are arranged on the separator film at a separation distance corresponding to at least one unit cell, and the unit cells after the second unit cell are arranged on the separator film in a form of an array in which distances between the unit cells are gradually increased corresponding to a winding width.

13. A secondary battery including the stacked/folded electrode assembly manufactured by the method of claim 8.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and advantages of the present disclosure will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic view of a conventional folding device for manufacturing a stacked/folded type electrode assembly;

(3) FIG. 2 is a schematic view showing a state in which a surplus winding end portion of a separator film is folded inward before being wound, when the folding device of FIG. 1 is used;

(4) FIG. 3 is a schematic view of a folding device for manufacturing a stacked/folded type electrode assembly according to one embodiment of the present disclosure;

(5) FIG. 4 is a schematic view showing a process in which a surplus winding end portion of a separator film is folded inward by rollers before being wound, when the folding device of FIG. 3 is used; and

(6) FIG. 5 is a schematic view showing a process in which the surplus winding end portion of the separator film is wound by a mandrel after being folded inward, when the folding device of FIG. 3 is used.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(7) Hereinafter, the present disclosure will be described in detail with reference to the drawings, but the scope of the present disclosure is not limited thereto.

(8) FIG. 3 is a schematic view of a folding device for manufacturing a stacked/folded type electrode assembly according to one embodiment of the present disclosure.

(9) Referring to FIG. 3, a folding device 100 according to the present disclosure is a folding device configured to arrange unit cells 121, 122, 123 and 124 to transfer to a mandrel 140 and the device includes a unit cell arrangement unit 120 configured to arrange the unit cells 121, 122, 123 and 124 on a separator film 110 at a predetermined interval, a pair of rollers 130 configured to vertically and horizontally bend a surplus winding end portion 111 of the separator film, which is formed by arranging a first unit cell 121 at a winding start portion in a state of being spaced apart from a winding end portion of the separator film, in a direction covering an upper surface of the first unit cell 121 and configured to press the unit cells, and the mandrel 140 configured to rotate and wind a web, in which the unit cells 121, 122, 123 and 124 are arranged on an upper surface of the separator film 110 at predetermined intervals, so that the unit cells 121, 122, 123 and 124 are sequentially stacked with the separator film 110 interposed therebetween.

(10) Here, the pair of rollers 130 include a first roller 131 located at a relatively upper portion and a second roller 132 located at a relatively lower portion with respect to the separator film 110 after the surplus winding end portion 111 is being horizontally bended.

(11) FIG. 4 is a schematic view for explaining a specific operation in which the pair of rollers 130 fold inward the surplus winding end portion 111 of the separator film in a direction covering the upper surface of the first unit cell 121. Here, the moving direction is indicated by an arrow.

(12) Referring to FIG. 4 together with FIG. 3, the first roller 131 and the second roller 132 move upward to vertically bend the surplus winding end portion 111 upward in a state of being positioned close to a boundary between the first unit cell 121 and the surplus winding end portion 111 of the separator film at a lower portion of the separator film 110, and move in a direction of the first unit cell 121 to horizontally bend the vertically bent surplus winding end portion 111 in a direction of the upper surface of the first unit cell 121, so that the surplus winding end portion 111 of the separator film may be folded inward in the direction of covering the upper surface of the first unit cell 121.

(13) Thereafter, in a state in which the web is interposed between the first roller 131 and the second roller 132, the first roller 131 moves downward and the second roller 132 moves upward, thereby performing a process of pressing the horizontally bent surplus winding end portion 111 on the first unit cell 121.

(14) FIG. 5 is a schematic view for explaining a process of winding the surplus winding end portion 111 by the mandrel to explain the process after the surplus winding end portion 111 of the separator film 110 is bent.

(15) Referring to FIG. 5 together with FIG. 3, the web horizontally moves in the direction in which the mandrel is placed for winding when the surplus winding end portion 111 of the separator film is folded inward in the direction of covering the upper surface of the first unit cell 121.

(16) The first unit cell 121 of the horizontally moved web and the surplus winding end portion 111 of the separator film, which is fixed to an upper portion of the first unit cell 121, are fixed together by grippers 141 and 142 of the mandrel, and then, the mandrel 140 rotates to start winding so that the unit cells 121, 122, 123, and 124 are sequentially stacked with the separator film 110 interposed therebetween.

(17) Here, the mandrel includes a first gripper 141 and a second gripper 142 located on both sides of the separator film with respect to the vertical direction based on the traveling direction of the separator film to effectively fix and wind the web, and each of the grippers 141 and 142 includes at least one upper leg 141 (a) configured to fix the surplus winding end portion 111 of the separator film and an upper surface portion of the first unit cell 121 and at least one lower legs 141 (b) configured to fix a lower surface portion of the separator film 110 corresponding to the upper leg 141 (a).

(18) In such a folding process, the first roller 131 and the second roller 132, which have performed the folding of the surplus winding end portion 111 of the separator film, are maintained in a pressing state to serve as a lamination roller for laminating the remaining unit cells 121, 122, 123, and 124 when the unit cells 121, 122, 123, 124 are transported later. Accordingly, a separate lamination roller is not required.

(19) As described above, since the first roller and the second roller fold the entire surplus winding end portion of the separator film and also horizontally bend the surplus winding end portion in the direction of the upper surface of the first unit cell, the rollers may hold the surplus winding end portion of the separator film to the end of a folding process. Accordingly, a phenomenon in which the separator film is blown and folded in the other direction, which is a problem that may occur when a wind is blown by using a method such as a blower to fold inward the surplus winding end portion of the separator film, may be prevented.

(20) Further, by allowing the rollers to inwardly fold the surplus winding end portion of the separator film and to press the folded surplus winding end portion together with the first unit cell so that the surplus winding end portion of the separator film is fixed to the upper surface of the first unit cell, the separator film may be prevented from folding out of the gripper of the mandrel, which may occur later secondarily during winding using the mandrel, so that a folding phenomenon of the separator film in the folding process may be completely eliminated.

(21) As described above, a folding device according to the present disclosure includes a pair of rollers configured to horizontally bend a surplus winding end portion of a separator film, which is formed by arranging a first unit cell at a winding start portion of a web in a state of being spaced apart from a winding end portion of the separator film, in a direction covering an upper surface of the first unit cell, and a stacked/folded type electrode assembly can be manufactured by using the folding device. Accordingly, the rollers can hold the surplus winding end portion of the separator film to the end of a folding process and thus the separator film can be prevented from being blown in the other direction, and since a process of pressing the folded separator film and first unit cell is performed after the rollers fold inward the surplus winding end portion of the separator film, a folding phenomenon of the separator film, which may occur secondarily during winding using a mandrel, can be prevented, thereby completely solving the conventional problems, remarkably reducing a defect rate, and improving the safety of a battery.

(22) Further, since the rollers can perform the function of pressing the separator film and unit cells which will be arranged later, a separate pressure roller is not required, and thus, the above described effects can be achieved without a great manufacturing cost difference in comparison with that of existing process equipment.

(23) It should be understood by those skilled in the art that various changes may be made without departing from the spirit and scope of the present disclosure.