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KR-102964588-B1 - Injection port sealing structure of battery can, battery cell, battery pack and vehicle using the same

KR102964588B1KR 102964588 B1KR102964588 B1KR 102964588B1KR-102964588-B1

Abstract

The present invention relates to a structure for sealing a cap injection port of a battery can. This includes an injection port (42) provided in a battery can (10) or cap (40) made of metal material; a stopper (50) made of metal material that seals the injection port (42); and a heat-fused portion interposed between the stopper (50) and the portion surrounding the injection port (42) and heat-fused to the portion surrounding the stopper (50) and the injection port (42) by heat. The heat-fused portion may include a first chrome coating layer (46) coated around the injection port (42), a second chrome coating layer (53) coated on the stopper (50), and a heat-fused layer (55) comprising PP-MAH (polypropylene-maleic anhydride) provided on either of the two chrome coating layers. The chrome oxide of the chrome coating layer and PP-MAH may be chemically bonded through heat fusion.

Inventors

  • 황동성
  • 신항수

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260513
Application Date
20230227
Priority Date
20220809

Claims (20)

  1. A metal battery can (10); A metal cap (40) covering the open end of the battery can (10); A liquid injection port (42) provided in the above cap (40); A metal stopper (50) covering the above injection port (42); and A heat-fused portion interposed between a first surface of the battery can (10) or cap (40) surrounding the injection port (42) and a second surface of the stopper (50) in contact with the first surface, and fused to at least a portion of the first surface and the second surface in a closed loop form surrounding the injection port (42); The above thermal fusion part is: A first chrome coating layer (46) formed on the first surface; A second chrome coating layer (53) formed on the second surface; and A heat-fusion layer (55) comprising PP-MAH (polypropylene-maleic anhydride) which has both sides in contact with the first chrome coating layer (46) and the second chrome coating layer (53) respectively and bonds to the first chrome coating layer (46) and the second chrome coating layer (53) by heat; Either of the first chrome coating layer (46) and the second chrome coating layer (53) forms the substrate of the PP-MAH of the heat-fused layer (55), and The above heat-fusion layer (55) is a non-substrate layer containing PP-MAH, and The electrode assembly (20) is further included, which is housed inside the battery can (10) and has a first electrode (21) and a second electrode (22), wherein the tab of the first electrode (21) and the tab of the second electrode (22) are each arranged on both sides in the axial direction. A battery cell having a first electrode terminal (13) that is electrically insulated from and fixed to the bottom portion (12) provided on the opposite side of the open end in the axial direction of the battery can (10).
  2. In claim 1, The above PP-MAH is provided as an insert injection molded onto either the first chrome coating layer (46) formed on the first surface or the second chrome coating layer (53) formed on the second surface, in a battery cell.
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  5. In claim 1, The above stopper (50) is provided with a central projection (51) that is inserted into the injection port (42), and A battery cell in which the center projection (51) contacts the inner surface of the battery can (10) or cap (40) defining the injection port (42), so that the center of the stopper (50) and the injection port (42) are aligned.
  6. In claim 5, The above central projection (51) penetrates the above injection port (42) in the depth direction, battery cell.
  7. In claim 5, The above central projection (51) is inserted only up to a portion of the depth direction of the above injection port (42), forming a battery cell.
  8. In claim 1, The above stopper (50) is provided with a central projection (51) that protrudes toward the injection port (42) at a position facing the injection port (42), and The above central projection (51) is a battery cell that is not inserted into the injection port (42).
  9. In claim 1, A recess (47) is provided around the above injection port (42) to accommodate the above stopper (50), and A battery cell in which the outer surface of the plug (50) contacts the inner surface of the recess (47), so that the center of the plug (50) and the injection port (42) are aligned.
  10. In claim 1, A recess (47) is provided around the above injection port (42) to accommodate the above stopper (50), and Around the above-mentioned recess (47), a protrusion (43) defining the above-mentioned recess (47) is provided, and The axial outer surface of the plug (50) received in the above-mentioned recess (47) corresponds axially to the surface of the above-mentioned protrusion (43) or is positioned further inwardly in the axial direction, forming a battery cell.
  11. In claim 1, The above first surface includes a first-1 surface facing the axial outer side of the battery cell, and The above second surface includes a second-1 surface facing the first-1 surface and looking inward in the axial direction, and The above-mentioned heat-fused portion is a battery cell provided between the first-1 surface and the second-1 surface.
  12. In claim 11, The first surface includes a first-second surface facing the radially inner side of the battery cell, and The second surface includes a second-2 surface facing the first-2 surface and looking outward in the radial direction, The above-mentioned heat-fused portion is a battery cell provided between the first-2 surface and the second-2 surface.
  13. In claim 11, The first surface includes a first-second surface facing the radially inner side of the battery cell, and The second surface includes a second-2 surface facing the first-2 surface and looking outward in the radial direction, A battery cell in which the above-mentioned heat-fused portion is not provided between the first-2 surface and the second-2 surface.
  14. In claim 1, The above stopper (50) and the battery can (10) or cap (40) to which the above stopper (50) is joined by the above heat fusion part are electrically conductive battery cells.
  15. In claim 1, The open end edge of the battery can (10) and the edge of the cap (40) are thermally bonded to the battery cell.
  16. In claim 15, A battery cell in which the thermal joining of the battery can (10) and cap (40) is performed by any one of the processes selected from welding, brazing, and soldering.
  17. In claim 1, A battery cell in which the first electrode (21) of the electrode assembly (20) is connected to the first electrode terminal (13) through a current collector plate (31) joined to the tab of the first electrode (21).
  18. In claim 1, The above cap (40) is a battery cell having an electrode connection portion (41) that is thermally joined to the tab of the second electrode (22) of the electrode assembly (20).
  19. In claim 18, A battery cell in which the thermal joining of the cap (40) and the tab of the second electrode (22) is performed by any one of the processes selected from welding, brazing, and soldering.
  20. In claim 18, The above injection port (42) is provided in the central part of the cap (40), and The above electrode connection part (41) is a battery cell that extends radially around the injection port (42).

Description

Injection port sealing structure of battery can, battery cell, battery pack and vehicle using the same The present invention relates to a structure for sealing the liquid injection port of a battery can, a battery cell to which the same is applied, a battery pack including said battery cell, and a vehicle equipped with said battery pack. Cylindrical battery cells feature a structure in which a jelly-roll type electrode assembly is housed inside a cylindrical metal can, making them more robust against shock and temperature changes than pouch-type batteries. Consequently, there is increasing demand for metal can-type cells for use in automotive battery packs. The process of manufacturing a battery cell using a cylindrical can consists of the steps of deep drawing a metal sheet to form a circular bottom portion and a circular tubular side wall portion connected thereto, accommodating an electrode assembly inside, and then covering the open end of the side wall portion with a cap to finish it. The method of covering the open end of the battery can with a cap and securing the cap to the battery can may involve crimping or seam welding. Crimping is a method in which an electrolyte is injected into the battery can through an open end, the open end is covered with a cap, the leading edge of the side wall of the battery can is beaded or crimped, and the edge of the cap is compressed to secure it. This crimping method is advantageous in that it does not degrade the electrolyte filled inside the battery can or generate heat capable of ignition during the processing; however, the fixing structure is complex, and the cap's fixing structure occupies the internal volume of the battery can, thereby reducing energy density. Referring to FIGS. 1 to 6, seam welding is a method of butting the perimeter of the leading edge of the side wall (11) of the battery can (10) and the perimeter of the edge of the cap (40) and welding them along the circumferential direction. Since the fixing structure is simple, the volume of the electrode assembly that can be accommodated inside the battery can is increased accordingly. Therefore, the seam welding method is more advantageous for securing electrical capacity relative to the same volume of the battery can. However, if the open end of the battery can is covered with a cap and welded after filling it with electrolyte, there is a possibility that the electrolyte may deteriorate or ignite due to the high temperature generated by the welding. Accordingly, when fixing the open end of the battery can and the cap by seam welding, a method may be applied in which a battery can (10) with an injection port provided at the bottom or a cap (40) with an injection port (42) is prepared, an electrode assembly is accommodated inside the battery can, the battery can (10) and the cap (40) are seam welded, an electrolyte is injected through the injection port (42) provided at the bottom of the cap or battery can, and after the injection is completed, the injection port is sealed with a stopper. As a method of closing the injection port after injecting the electrolyte through the injection port (42), a metal plug core welding method, a blind rivet method, or a metal ball insertion method may be used. First, referring to FIGS. 1 and 2, the metal stopper seam welding is a method of covering the liquid injection port (42) provided in the battery can (10) with a metal stopper (50) and seam welding the rim of the stopper (50) to the cap (40) to form a weld (W). In the case where the materials of the battery can and the cap are SUS, the surface temperature of the seam welding can rise to 1400 degrees Celsius, which is the melting point of SUS. Such high heat can cause the electrolyte to ignite. In other words, the method of sealing the liquid injection port by seam welding a metal stopper when closing the liquid injection port directly contradicts the purpose of introducing the liquid injection port structure to minimize the effect of the heat generated when seam welding the open end of the battery can and the cap on the electrolyte. Furthermore, to prevent this phenomenon, an additional structure capable of preventing the ignition of the electrolyte may be applied, but this also inevitably takes up more volume within the battery cell's internal space, which is disadvantageous for securing the electrical capacity of the battery can. The sealing method using blind rivets (58) shown in FIGS. 3 and 4 is a method of mechanically sealing by plastically deforming the metal, so a large load is applied to the joint. This load can cause damage to the coating formed on the surface of the cap (40) and rivet (58) to prevent leakage. That is, if the load is lowered to prevent coating damage, the sealing function weakens, and if the load is increased to enhance the sealing function, the coating is damaged and there is a risk that the seal will break. In addition, since the rivet is inserted into the can before riveting, a space