Cylindrical battery cell, battery pack and vehicle

Abstract

Battery cell comprising: a battery case 10 having a side wall 11 and an open end provided at one axial end; an electrode assembly 20 provided with a first electrode 21 and a second electrode 22 and received in the battery case 10 in such a manner that a tab 27 of the second electrode 22 faces the open end; and a cap 40 covering the open end of the battery case 10 and connected to the second electrode 22, wherein the side wall 11 is provided with a contact wall surface portion 113 provided at the open end of the battery case 10 and extending outward in the axial direction, wherein an inner peripheral surface of the side wall 11 has a diameter that widens at the contact wall surface portion 113, wherein the cap 40 is provided with: a contact surface portion 48 extending in the axial direction such that an outer peripheral surface thereof is in contact with an inner peripheral surface of the contact wall surface portion 113; and an electrode connection part 41 electrically connected to the tab 27 of the second electrode 22, and wherein an axial outer edge of the inner peripheral surface of the contact wall surface portion 113 and an axial outer edge of the outer peripheral surface of the contact surface portion 48 are connected.

Description

TECHNICAL FIELD

[0001] This application claims priority from Korean patent application KR 10-2022-0136789, filed on October 21, 2022, and Korean patent application KR 10-2023-0026204, filed on February 27, 2023, all content disclosed in the documents of the patent applications being incorporated as part of this specification.

[0002] The present invention relates to a cylindrical battery cell, a battery pack and a vehicle having the same. TECHNICAL BACKGROUND

[0003] A cylindrical battery cell has a structure in which a jellyroll-shaped electrode array is housed in a cylindrical metal casing, making it more robust against shock and temperature than pouch-type batteries. Therefore, the demand for casing-type battery cells for automotive battery packs is increasing.

[0004] The process of manufacturing a battery cell using a cylindrical casing typically includes: performing deep drawing on a metal foil to form a circular bottom and a circular tubular sidewall connected to the circular bottom; accommodating an electrode assembly in the cylindrical casing; and then covering (closing) an open end of the sidewall with a cap.

[0005] Here, as in Fig. As shown in Figure 1, the side wall 11 of the housing and the cap 40 are butt-welded. If there is a gap between them, the welding laser L may penetrate the interior of the housing, causing damage to the electrode assembly. Furthermore, the thickness of the welded portion is thin, so sufficient weld strength cannot be guaranteed even after welding is completed. Furthermore, if there is a height difference between the side wall of the housing and the cap, the risk of weld defects increases.

[0006] The battery case is typically made of metal, and therefore cylindrical battery cells can be heavier than pouch-type battery cells. Therefore, active research is being conducted to increase the electrical capacity of a single battery case by increasing the capacity of individual battery cases.

[0007] As the capacity of the battery case increases, the diameter becomes larger, so that a structure is possible in which both the positive terminal and the negative terminal are arranged on one axial side of the battery, for example, on the top side of the battery case, unlike the prior art.

[0008] The process of manufacturing a battery cell using a cylindrical casing described above typically includes: a casing preparation step of performing deep drawing on a metal foil to form a circular bottom 12 and a circular tubular side wall 11 connected to the circular bottom 12, and attaching a first electrode terminal to the center of the circular bottom of the casing; and an electrode assembly preparation step of preparing a jellyroll-like electrode assembly provided with a first current collector plate and a second current collector plate at two axial ends thereof.The process further includes an assembling step of receiving the electrode assembly in the housing, connecting the first current collector plate to the first electrode terminal, connecting the second current collector plate to the housing or the cap, filling the interior of the housing with an electrolyte solution, and covering (closing) the open end of the side wall with a cap.

[0009] Since the cylindrical battery cell manufactured as described above needs to secure a space (capacity) within a casing to accommodate the second current collector plate, the capacity of the electrode assembly must be reduced accordingly, which is problematic in terms of energy density loss. Furthermore, during the process of preparing the electrode assembly, an additional process for bonding the second current collector plate to the second electrode of the electrode assembly is required, thereby increasing the number of processes. Furthermore, adding the second current collector plate as a component and adding the process for bonding it to the second electrode of the electrode assembly results in an increase in the manufacturing cost of the battery cell.

[0010] Since the current collector plate is flexible to a certain extent, welding the current collector plate to the electrode of the electrode assembly and connecting the current collector plate to the electrode terminal of the battery case is advantageous in that the reliability of the electrical connection is increased compared to the structure in which the electrode of the electrode assembly is directly connected to the electrode terminal of the battery case without the current collector plate.

[0011] Therefore, the structure in which the electrode of the electrode assembly is directly connected to the electrode terminal of the battery case without the current collector plate to increase the energy density of the battery cell cannot be said to be an improved structure compared to the structure using the current collector plate. SUMMARY OF THE INVENTION TECHNICAL TASK

[0012] To solve the problems described above, the present invention provides a structure of a battery cell in which the adhesion between the cap and the electrode tab of the electrode assembly is increased while preventing the butt welding process between the side wall of the case and the cap from affecting the electrode assembly by the butt connection between the side wall of the case and the cap not regulating the insertion depth of the cap.

[0013] Furthermore, the present invention provides a battery cell having a structure in which the contact wall surface portion around the side wall and the contact surface portion of the cap can be closely abutted without being deformed during the process of press-fitting the cap into the open end of the case.

[0014] Furthermore, the present invention provides a battery cell having a structure according to which the connecting portion between the cap and the battery case can be protected.

[0015] Furthermore, the present invention provides a battery cell that ensures the reliability of the electrical connection between the electrode of the electrode assembly and the electrode terminal of the battery case, while eliminating the current collector plate when connecting the electrode assembly to the electrode terminal of the case.

[0016] Furthermore, the present invention provides a battery cell that can be manufactured at reduced costs by having a smaller number of parts and simpler manufacturing processes.

[0017] Furthermore, the present invention provides a battery cell having a high energy density and therefore advantageous for mounting in a vehicle, and a battery pack and a vehicle incorporating the same.

[0018] The technical problems to be solved by the present invention are not limited to the objects described above. Other objects and advantages of the present invention not described above can be understood from the following description and will be more clearly understood from the examples of the present invention. Furthermore, it is obvious that the objects and advantages of the present invention can be implemented by the means recited in the claims and combinations thereof. MEANS FOR SOLVING THE TASK(S)

[0019] To solve the problems described above, the present invention can be applied to a battery cell in which the edges of the side wall 11 and the cap 40 are joined to electrically connect the battery case 10 and the cap 40, wherein the electrode assembly 20 is accommodated in the battery case 10.

[0020] The battery housing 10 has a bottom 12 and a side wall 11 which is connected to the bottom 12 and extends in the axial direction.

[0021] The cap 40 covers the open end provided at one axial end of the battery case 10.

[0022] The side wall 11 is provided with a contact wall surface portion 113 provided at the open end of the battery case 10 and extending outward in the axial direction, wherein an inner peripheral surface of the side wall 11 has a diameter that widens at the contact wall surface portion 113.

[0023] The cap 40 is provided with a contact surface portion 48 extending in the axial direction so that an outer peripheral surface thereof can be in contact with an inner peripheral surface of the contact wall surface portion 113.

[0024] The cap 40 is provided with an electrode connecting part 41 which is electrically connected to the tab 27 of the second electrode 22.

[0025] An offset of the cap 40 with respect to the battery case 10 is defined by a portion connecting the electrode connecting part 41 of the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 accommodated in the battery case 10.

[0026] The inner peripheral surface of the contact wall surface portion 113 and the outer peripheral surface of the contact surface portion 48 are joined to be electrically connected.

[0027] A portion connecting an inner peripheral surface of the side wall 11 where an inner diameter thereof varies and the contact wall surface portion 113 may not regulate an insertion depth of the cap 40 with respect to the battery case 10. Therefore, the insertion depth of the cap 40 with respect to the battery case 10 may be determined by the electrode connecting part 41.

[0028] A length cf of the contact surface portion 48 in the axial direction may be shorter than a length ce of the contact wall surface portion 113 in the axial direction. Therefore, the lower end portion of the contact surface portion 48 can be prevented from being press-fitted into the portion connecting the side wall 11 and the contact wall surface portion 113.

[0029] At the same time, the portion connecting the side wall 11 where the inner diameter thereof varies and the contact wall surface portion 113 prevents the joining process of the inner peripheral surface of the contact wall surface portion 113 and the outer peripheral surface of the contact surface portion 48 from affecting the performance of the electrode assembly 20 accommodated in the battery case 10.

[0030] Joining may include welding, brazing, and soldering.

[0031] Joining may include seam welding.

[0032] Welding can be performed by a laser radiated in the axial direction.

[0033] The joining process may include welding by irradiating a laser onto the axial outer edge of the inner peripheral surface of the contact wall surface portion 113 and the axial outer edge of the outer peripheral surface of the contact surface portion 48.

[0034] Even if the laser irradiated in the axial direction for connecting the contact wall surface portion 113 and the contact surface portion 48 penetrates into the interior of the battery case 10 due to an unexpected gap therebetween, the laser can be blocked by the portion connecting the side wall 11 and the contact wall surface portion 113. Thus, the electrode assembly 20 inside the battery case 10 can be prevented from being exposed to the laser.

[0035] A tapered surface portion 115 which becomes narrower radially inward toward an axial inner side so as to have a substantially constant first inclination m may be provided at the portion connecting the inner peripheral surfaces of the side wall 11 and the contact wall surface portion 113 between the inner peripheral surface of the side wall 11 and the inner peripheral surface of the contact wall surface portion 113.

[0036] An axially inner end of the contact surface portion 48 may be connected to a curved surface portion 47 extending radially inward toward an axially inner side such that an inclination of a tangent to an outer peripheral surface thereof gradually decreases.

[0037] A point P where the inclination of the tangent to the outer peripheral surface of the curved surface portion 47 may be equal to the first inclination m may be located radially further inward than the tapered surface portion 115.

[0038] Thus, an inclination of the portion of the curved surface portion 47 facing the tapered surface portion 115 in the axial direction, that is, an inclination of a portion of the curved surface portion 47 in the radial direction corresponding to where the tapered surface portion 115 is provided in the radial direction of the cylindrical battery cell 72, may be larger than the first inclination m of the tapered surface portion 115.

[0039] Consequently, even if the curved surface portion 47 comes into contact with the tapered surface portion 115 due to a manufacturing error during the process of press-fitting the cap 40 into the battery case 10, the curved surface portion 47 only comes into contact with the boundary g between the tapered surface portion 115 and the side wall 11. Thus, the curved surface portion 47 is deformed due to its steep inclination, enabling the press-fitting of the cap 40.

[0040] The point P, where the inclination of the tangent to the outer peripheral surface of the curved surface portion 47 may be equal to the first inclination m, may be located axially further inward than the tapered surface portion 115.

[0041] Consequently, the laser reaching the tapered surface portion 115 through an unexpected gap between the contact surface portion 48 and the contact wall surface portion 113 can disappear between the surface of the tapered surface portion 115 and the surface of the curved surface portion 47 without penetrating inside, because the inclination of the surface of the curved surface portion 47 is larger than that of the opposite surface of the tapered surface portion 115.

[0042] The cap 40 may have a base surface portion 45 located radially further inward than the contact surface portion 48, with the base surface portion 45 extending horizontally in the radial direction. Since the base surface portion 45 provides an annular flat surface adjacent to the edge of the battery case 10 in the radial direction, the battery cell can be stably placed on the ground.

[0043] An axially outer side surface of the base surface portion 45 may be located axially further outward than an axially outer end of the contact surface portion 48. That is, the height d of the axially outer side surface of the base surface portion 45 may be higher than the height c of the axially outer end of the contact surface portion 48. Thus, when the battery cell is placed on the floor in an upright orientation, the connecting region M of the contact surface portion 48 and the contact wall surface portion 113 is not directly subjected to a load, thereby protecting the connecting region M.

[0044] A first inclined surface portion 46, which has a substantially constant inclination and extends axially outward toward a radially outer side, may be provided between the curved surface portion 47 and the base surface portion 45. The curved surface portion 47 and the base surface portion 45 are elastically deformed radially inward and increase the adhesion of the contact surface portion 48 and the contact wall surface portion 113 during the press-fitting process of the cap 40, thereby enabling the bonding process to be performed smoothly.

[0045] The electrode connecting part 41 may be provided at a position radially inward than the base surface portion 45.

[0046] The electrode connecting part 41 may be recessed in the axial direction with respect to the base surface portion 45.

[0047] The electrode connecting part 41 can be formed by plastically working a predetermined portion of the cap 40 made of a metal foil to be recessed toward the axial inside.

[0048] A second inclined surface portion 49 having a substantially constant inclination and extending axially inward toward a radially outer side may be provided between the electrode connecting part 41 and the base surface portion 45.

[0049] The electrode connecting part 41 can extend radially outward by more than 0.5 times the radius of the battery housing 10. Thus, a sufficient connection length in the radial direction can be ensured between the electrode connecting part 41 and the tab of the second electrode 22.

[0050] Preferably, the electrode connecting part 41 can extend radially outward by more than 0.7 times the radius of the battery case 10.

[0051] The electrode connecting part 41 may provide a bottom surface extending flat in the radial direction.

[0052] The height a of the bottom surface of the electrode connecting part 41 may be lower than the height b of the lower end portion of the curved surface portion 47. That is, the electrode connecting part 41 may protrude further inward in the axial direction than the curved surface portion 47.

[0053] Consequently, the bottom surface of the electrode connecting part 41 can be in close contact with the tab of the second electrode 22 of the electrode assembly 20, while the lower end portion of the curved surface portion 47 is spaced axially from the electrode assembly 20 accommodated in the battery case 10. Thus, the connection process between the electrode connecting part 41 and the tab of the second electrode 22 can be performed smoothly.

[0054] In one embodiment, a liquid introduction port 42 may not be provided on the electrode connecting part 41.

[0055] In another embodiment, a liquid introduction port 42 is provided on the electrode connecting part 41.

[0056] A liquid introduction port 42 may be provided at a central portion of the electrode connecting part 41.

[0057] The liquid introduction port 42 may be provided at a protruding portion 43 that protrudes axially further outward than the electrode connecting part 41 around the liquid introduction port 42.

[0058] A plurality of electrode connecting parts 41 may be provided, and each electrode connecting part 41 may be recessed toward the inside of the battery case 10 and extend in the radial direction.

[0059] The plurality of electrode connecting parts 41 may be arranged radially with respect to the center of the cap 40.

[0060] The plurality of electrode connecting parts 41 may be arranged at equal intervals in the circumferential direction.

[0061] A pair of electrode connecting parts 41 facing each other with respect to the center of the cap 40 may be arranged along a straight line.

[0062] Four electrode connecting parts 41 may be provided at 90-degree intervals.

[0063] An outer surface portion 44, which projects further outward in the axial direction than the electrode connecting part 41, may be provided between two circumferentially adjacent electrode connecting parts 41.

[0064] The outer surface portion 44 may be connected to a radially inner side of the base surface portion 45.

[0065] A projection height of the outer surface portion 44 may be equal to or lower than that of the base surface portion 45.

[0066] When the protrusion height of the outer surface portion 44 is equal to that of the base surface portion 45, the outer surface portion 44 also comes into contact with the ground when the battery cell is placed on the ground. Therefore, the dimension of the base surface portion 45 in the radial direction can be minimized. Thus, the length of the electrode connecting part 41 in the radial direction can be further secured.

[0067] The outer surface portion 44 may protrude axially further outward than the projecting portion 43.

[0068] The protruding portion 43 may be connected to a radially inner side of the outer surface portion 44.

[0069] The cap 40 may be provided with a vent 60.

[0070] The vent 60 may be provided radially further outward than the electrode connecting part 41.

[0071] The vent 60 may be provided around a radially central portion of the base surface portion 45.

[0072] The vent 60 may be defined by a thin portion provided in the cap 40.

[0073] The vent 60 may be defined by a stopper 50 that covers (and closes) the liquid introduction opening 42.

[0074] The vent 60 may be defined by a connecting area between the cap 40 and the battery housing 10.

[0075] A first electrode terminal 13 may be installed at the central portion of the bottom 12 of the battery case 10.

[0076] The first electrode terminal 13 may be installed on the floor 12 while being electrically insulated from the floor 12.

[0077] The bottom 12 around the first electrode terminal 13 forms a second electrode terminal 15, and the side wall 11 connected to the bottom 12 can also form a second electrode terminal.

[0078] The electrode assembly 20 is manufactured by winding the first electrode 21 and the second electrode 22 in a jellyroll shape.

[0079] The electrode assembly 20 is received in the battery case 10, being aligned with the battery case 10 in the axial direction.

[0080] The liquid introduction port 42 and the hollow core portion of the electrode assembly 20 may be aligned in the axial direction.

[0081] The tab of the first electrode 21 can be arranged at an axial end of the electrode assembly 20.

[0082] The tab may be a portion of the metal foil 23 of the first electrode 21 that extends toward an axial end of the electrode assembly 20.

[0083] The tab portions of the first electrode 21 may be bent in the radial direction and overlap each other to provide a plane substantially perpendicular to the axial direction.

[0084] A current collector plate 31 may be connected to the tab of the first electrode 21.

[0085] The current collector plate 31 may be connected to the first electrode terminal 13.

[0086] Thus, the first electrode terminal 13 can have a first polarity.

[0087] The tab of the second electrode 22 may be arranged at the other axial end of the electrode assembly 20.

[0088] The tab may be a portion of the metal foil 23 of the second electrode 22 that extends toward the other axial end of the electrode assembly 20.

[0089] The tab portions of the second electrode 22 are bent in the radial direction and overlap each other to provide a plane substantially perpendicular to the axial direction.

[0090] The tab of the second electrode 22 may be arranged at the open end.

[0091] The cap 40 may be electrically connected to the tab of the second electrode 22.

[0092] A current collector plate 31 may be connected and electrically connected to the tab of the second electrode 22, and the electrode connecting part 41 may be connected to the current collector plate 31 to be electrically connected to the tab of the second electrode 22.

[0093] Thus, the cap 40 and the battery case 10 can have a second polarity.

[0094] The electrode connecting part 41 can be directly connected and electrically connected to the tab of the second electrode 22.

[0095] The connected portion of the electrode connecting part 41 and the tab of the second electrode 22 may extend in the radial direction.

[0096] The electrode connecting part 41 and the tab of the second electrode 22 may be joined, fixed, and electrically connected to each other by a welding portion W formed by a laser irradiated onto the surface of the electrode connecting part 41 along the radial direction.

[0097] The electrode connecting part 41 and the tab of the second electrode 22 can be connected and fixed using a method other than welding. For example, brazing or soldering can be used.

[0098] The connection between the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 can be made with the electrode assembly 20 accommodated in the battery housing 10 and the cap 40 pressed into the battery housing 10.

[0099] The connection between the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 is preferably established before the cap 40 and the battery housing 10 are connected. However, the connection between the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 can also be established after the cap 40 and the battery housing 10 are connected.

[0100] The cap 40 can be pressed into the battery case 10 after an electrolyte solution has been introduced into the battery case 10.

[0101] The cap 40 can be pressed into the battery case 10 before the electrolyte solution is introduced into the battery case 10. Thus, the connection between the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 and the fastening of the cap 40 and the battery case 10 can be performed before the electrolyte solution is introduced into the battery case 10.

[0102] The cap 40 can be connected to the tab of the second electrode 22 before the electrode assembly 20 is received in the battery case 10.

[0103] Furthermore, the present invention provides a method for manufacturing a battery cell having a cap applied thereto.

[0104] A manufacturing method according to a first embodiment includes a battery case preparation step, an electrode assembly preparation step, a cap preparation step, an electrode assembly receiving step, a first electrode terminal connecting step, a liquid introducing step, a cap press-fitting step, and a cap fixing step.

[0105] The battery case preparation step includes: preparing a battery case 10 having a side wall 11, a bottom 12 provided at one axial end thereof, and an open end provided at the other axial end thereof; and forming a contact wall surface portion 113 at the open end having an enlarged inner diameter, and fixing and insulating a first electrode terminal 13 to a central portion of the bottom 12.

[0106] The electrode assembly preparation step includes manufacturing an electrode assembly 20 provided with a first electrode 21 and a second electrode 22 having tabs disposed on a respective axial side of the two axial sides.

[0107] The cap preparation step includes manufacturing a cap 40 provided with: a contact surface portion 48 extending in the axial direction so that an outer peripheral surface thereof can be in contact with an inner peripheral surface of the contact wall surface portion 113; and an electrode connection part 41 electrically connected to the tab of the second electrode 22.

[0108] The electrode assembly receiving step includes receiving an electrode assembly 20 in the battery case 10 in such a manner that the tab of the first electrode 21 faces the bottom 12 of the battery case 10 after the battery case preparing step and the electrode assembly preparing step.

[0109] The first electrode terminal connecting step includes connecting the tab of the first electrode 21 and the first electrode terminal 13 after the electrode assembly receiving step.

[0110] The liquid introduction step includes introducing an electrolyte solution into the battery case 10 after the first electrode terminal connecting step.

[0111] The cap press-fitting step includes press-fitting the cap 40 into the open end of the battery case 10 to bring the electrode connecting part 41 into close contact with the tab of the second electrode 22 after the cap preparation step and the liquid introduction step; and

[0112] The cap-attaching step includes: bonding and electrically connecting the electrode connecting part 41 to the tab of the second electrode 22; and bonding and electrically connecting the contact surface portion 48 to an inner peripheral surface of the contact wall surface portion 113 after the cap-pressing step.

[0113] The manufacturing method according to the first embodiment can be applied to the manufacture of a battery cell provided with a cap without a liquid introduction port.

[0114] A manufacturing method according to a second embodiment includes a battery case preparation step, an electrode assembly preparation step, a cap preparation step, an electrode assembly receiving step, a first electrode terminal connecting step, a cap press-fitting step, a cap fixing step, and a liquid introducing step.

[0115] The battery case preparation step includes preparing a battery case 10 having: a side wall 11; a bottom 12 provided at one axial end thereof; and an open end provided at the other axial end thereof; and forming a contact wall surface portion 113 at the open end having an expanded inner diameter; and fixing and insulating a first electrode terminal 13 to a central portion of the bottom 12.

[0116] The electrode assembly preparation step includes manufacturing an electrode assembly 20 provided with a first electrode 21 and a second electrode 22 having tabs disposed on a respective axial side of the two axial sides.

[0117] The cap preparation step includes manufacturing a cap 40 provided with: a contact surface portion 48 extending in the axial direction so that an outer peripheral surface thereof can be in contact with an inner peripheral surface of the contact wall surface portion 113; an electrode connection part 41 electrically connected to the tab of the second electrode 22; and a liquid introduction port 42 provided in the central portion of the electrode connection part 41.

[0118] The electrode assembly receiving step includes receiving an electrode assembly 20 in the battery case 10 in such a manner that the tab of the first electrode 21 faces the bottom 12 of the battery case 10 after the battery case preparing step and the electrode assembly preparing step.

[0119] The first electrode terminal connecting step includes connecting the tab of the first electrode 21 and the first electrode terminal 13 after the electrode assembly receiving step.

[0120] The cap press-fitting step includes press-fitting the cap 40 into the open end of the battery case 10 to bring the electrode connecting part 41 into close contact with the tab of the second electrode 22.

[0121] The cap-attaching step includes: connecting and electrically connecting the electrode connecting part 41 to the tab of the second electrode 22; and connecting and electrically connecting an outer peripheral surface of the contact surface portion 48 to an inner peripheral surface of the contact wall surface portion 113 after the cap-pressing step; and

[0122] The sealing and closing step includes introducing an electrolyte solution into the battery case 10 through the liquid introduction port 42 and sealing and closing the liquid introduction port 42 after the first electrode terminal connecting step and the cap fixing step.

[0123] A manufacturing method according to a third embodiment includes a battery case preparation step, an electrode assembly preparation step, a cap preparation step, a second electrode terminal connecting step, an electrode assembly receiving and cap press-fitting step, a first electrode terminal connecting and cap fixing step, and a liquid introducing step.

[0124] The battery case preparation step includes preparing a battery case 10 having: a side wall 11; a bottom 12 provided at one axial end thereof; and an open end provided at the other axial end thereof; and forming a contact wall surface portion 113 at the open end having an expanded inner diameter; and fixing and insulating a first electrode terminal 13 to a central portion of the bottom 12.

[0125] The electrode assembly preparation step includes manufacturing an electrode assembly 20 provided with a first electrode 21 and a second electrode 22 having tabs disposed on a respective axial side of the two axial sides.

[0126] The cap preparation step includes manufacturing a cap 40 provided with: a contact surface portion 48 extending in the axial direction so that an outer peripheral surface thereof can be in contact with an inner peripheral surface of the contact wall surface portion 113; an electrode connection part 41 electrically connected to the tab of the second electrode 22; and a liquid introduction port 42 provided in the central portion of the electrode connection part 41.

[0127] The second electrode connecting step includes connecting and electrically connecting the tab of the second electrode 22 to the electrode connecting part 41 of the cap 40 after the electrode assembly preparing step and the cap preparing step.

[0128] The electrode assembly receiving and cap press-fitting step includes receiving an electrode assembly 20 in the battery case 10 in such a manner that the tab of the first electrode 21 faces the bottom 12 of the battery case 10, and press-fitting the cap 40 into the open end of the battery case 10 after the battery case preparing step and the electrode terminal connecting step.

[0129] The first electrode terminal connecting and cap fixing step includes connecting the tab of the first electrode 21 and the first electrode terminal 13 and connecting and electrically connecting an outer peripheral surface of the contact surface portion 48 to an inner peripheral surface of the contact wall surface portion 113 after the electrode assembly receiving step and the cap press-fitting step.

[0130] The sealing and closing step includes introducing an electrolyte solution into the battery case 10 through the liquid introduction port 42 and sealing and closing the liquid introduction port 42 after the first electrode terminal connecting step and the cap fixing step.

[0131] The manufacturing methods according to the second embodiment and the third embodiment can be applied to the manufacture of a battery cell provided with a cap having a liquid introduction port.

[0132] The present invention provides a high energy density battery pack including the battery cell described above.

[0133] The present invention provides a vehicle equipped with a high energy density battery pack, thereby reducing the volume or weight of the battery pack. EFFECTS OF THE INVENTION

[0134] According to the present invention, when the inner peripheral surface of the casing and the outer peripheral surface of the cap are joined with a difference between the inner diameters of the side wall and the contact wall surface, the influence of the joining process on the electrode assembly in a battery can be prevented.

[0135] Furthermore, according to the present invention, since the housing does not regulate the insertion depth of the cap, the adhesion between the cap and the electrode tab of the electrode assembly can be increased, thereby allowing the cap to function as a current collector plate.

[0136] In addition, according to the present invention, since the point at which the inclination of the tangent of the curved surface portion is equal to the inclination of the tapered surface portion is located radially inward than the tapered surface, the side wall does not affect the depth of the press fit of the cap, and the joining process of the housing and the electrode of the electrode assembly can be performed smoothly.

[0137] Furthermore, according to the present invention, since the point at which the inclination of the tangent of the curved surface portion is equal to the inclination of the tapered surface portion is located axially further inward than the tapered surface, the influence of the bonding process of the housing and the cap on the electrode assembly can be prevented despite a gap between the side wall and the housing.

[0138] Furthermore, according to the present invention, since the curved surface portion and the first inclined surface portion are arranged in the shape of a swan neck between the contact surface portion of the cap and the base surface, the contact wall surface portion around the side wall and the contact surface portion of the cap can be closely abutted without being deformed during the process of press-fitting the cap into the open end of the housing.

[0139] Furthermore, according to the present invention, since the base surface portion is placed axially further outward than the welding area, the welding area can be protected even if the cylindrical battery cell is placed with the cap placed on the bottom.

[0140] According to the present invention, since the cap is directly and electrically connected and fixed to the tab of the second electrode, and the cap is electrically connected and fixed to the side wall of the housing, the current collector plate can be eliminated, thereby increasing the energy density of the battery cell, reducing the number of parts of the battery cell, and simplifying the manufacturing process. Thus, the manufacturing cost of the battery cell can be reduced.

[0141] According to the present invention, since the electrode connecting part of the cap connected to the tab of the second electrode extends along the radial direction, the cap is directly and electrically connected from the core to the outer periphery of the second electrode, thereby significantly reducing the internal resistance.

[0142] According to the present invention, since the cap is provided with a plurality of electrode connecting parts extending in the radial direction, and each of the plurality of electrode connecting parts is recessed axially inward and thereby protrudes toward the tab of the second electrode, the adhesion between each electrode connecting part and the second electrode can be secured, thereby ensuring their connection quality.

[0143] Since such a shape greatly improves the cap's torsional resistance, the overall adhesion between the cap's attached portion and the battery case along the circumferential direction can also be improved. Therefore, the bonding quality of the battery case and the cap can also be greatly improved.

[0144] Since the electrode connecting parts of the cap according to the present invention are arranged radially at equal intervals in the circumferential direction, the deformation resistance can be secured uniformly along the circumferential direction and the current path can be evenly distributed.

[0145] According to the present invention, since a pair of electrode connecting parts facing each other with respect to the center of the cap are aligned along a line, the shape of a jig for press-fitting the cap into the battery case or for bringing the cap into close contact with the electrode assembly can be easily implemented, and the traces of the welding line can be simplified.

[0146] According to the present invention, since four electrode connecting parts are arranged at 90-degree intervals, the deformation resistance of the cap can be secured and the welding process can be simplified while maintaining the adhesion of each of the plurality of electrode connecting parts to the tab of the second electrode and suppressing the deterioration of the rigidity of the cap due to the resin processing by reducing the number of resin processing points of the cap.

[0147] According to the present invention, since an outer surface portion located axially further outward than the electrode connecting part is provided on the cap between two circumferentially adjacent electrode connecting parts, the connecting area between the cap and the electrode of the electrode assembly can be protected.

[0148] According to the present invention, when the battery case is placed in an upright orientation, that is, when the base surface portion and the outer surface portion are placed on the ground, the base surface portion and the outer surface portion are capable of supporting the weight of the battery cell. Accordingly, the outer surface portion, located on both sides of the electrode connecting part in the circumferential direction, exerts the action of pressing the electrode connecting part toward the tab of the second electrode, thereby minimizing damage to the connection area between the cap and the tab of the second electrode due to vibration or shock.

[0149] Since the liquid introduction port provided in the central portion of the cap protrudes further than the electrode connecting part, it is possible to minimize the conduction of welding heat or joining heat to the electrode assembly generated when the liquid introduction port is closed with a stopper.

[0150] If the vent provided in the cap is positioned radially outwardly than the electrode connection part or the welding section, the large area of ​​the cap where the internal pressure of the battery case is applied can be secured, and the venting effect can be facilitated. If the venting area is damaged due to the venting, the electrical connection between the second electrode and the battery case may be severed.

[0151] According to the present invention, the vent is provided in the radially central portion of the base surface portion. Therefore, damage to the vent caused by inadvertent external force can be prevented because the load applied to the base surface portion due to the weight of the battery cell or by the structure connected to the battery cell is borne by the housing and the electrode assembly through the electrode connecting part and the first inclined surface portion, rather than being transmitted to the vent.

[0152] In addition to the advantageous effects described above, specific effects of the present invention will be further described while describing specific details of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is an enlarged view of the area where a cap is press-fitted into a battery case. Fig. 2 is a perspective view of a battery case that can be applied to a battery cell according to an embodiment. Fig. 3 and Fig. 4 are perspective views illustrating before and after laminating a first electrode, a second electrode and separators to produce an electrode assembly to be housed in a battery case, and Fig. 5 is a plan view taken after laminating the first electrode, the second electrode and the separators shown in Fig. 4 are illustrated. Fig. 6 and Fig. 7 are perspective views and side views of an electrode assembly formed by winding the laminate of Fig. 4 and Fig. 5 into a jellyroll shape. Fig. 8 and Fig. 9 are perspective views illustrating an electrode assembly with a current collector plate attached to an upper portion thereof without a current collector plate attached to a lower portion thereof. Fig. 10 is a cross-sectional view showing a process of picking up the electrode assembly from Fig. 8 and Fig. 9 into a battery housing. Fig. 11 is a cross-sectional view illustrating a process of welding a first electrode terminal and the current collector plate. Fig. 12 is a diagram illustrating a process of press-fitting a cap into a battery case. Fig. 13 is a cross-sectional view illustrating an electrode connecting part of a cap connected to a tab of a second electrode of an electrode assembly and a contact surface portion of the cap connected to a contact wall surface portion of a battery case. Fig. 14 to Fig. 16 show an upper perspective view, a lower perspective view and a top view of a cap according to a first embodiment. Fig. 17 is a cross-sectional view showing the corresponding section of Fig. 16 illustrates. Fig. 18 is an enlarged view showing an edge of the cap of Fig. 17 illustrates. Fig. 19 is a diagram illustrating a process of assembling a battery case by applying a cap according to the first embodiment. Fig. 20 is an enlarged view of the distal part of the open end of Fig. 19. Fig. 21 is an enlarged view of the connection area between the housing and the cap of Fig. 20. Fig. 22 is an enlarged view of a tapered surface portion of the housing and a curved surface portion of the cap in Fig. 21. Fig. 23 is a top perspective view of a cap according to a second embodiment. Fig. 24 is a cross-sectional view of the corresponding section of Fig. 23. Fig. 25 and Fig. 26 are diagrams illustrating a process of assembling a battery case by applying a cap according to the second embodiment. Fig. 27 is a bottom perspective view of a cap attached to a tab of a second electrode of an electrode assembly. Fig. 28 to Fig. 30 are an upper perspective view, a lower perspective view, and a top view of a cap according to a third embodiment. Fig. 31 and Fig. 32 are cross-sectional views of the corresponding section of Fig. 30. Fig. 33 is a diagram illustrating a process of assembling a battery case with the cap according to the third embodiment. Fig. 34 to Fig. 36 are an upper perspective view, a lower perspective view, and a top view of a cap according to a fourth embodiment. Fig. 37 to Fig. 39 are cross-sectional views of the corresponding section of Fig. 36. Fig. 40 and Fig. 41 are diagrams illustrating a process of assembling a battery case by the cap according to the fourth embodiment. Fig. 42 to Fig. 44 are flowcharts illustrating methods for assembling a battery cell with the cap according to embodiments. Fig. 45 and Fig. 46 illustrate a battery pack with a battery cell attached thereto according to an embodiment and a vehicle equipped with the battery pack. REFERENCE SYMBOL

[0153] 10: Battery case; 11: Side wall; 111: Press-fit guide surface portion; 113: Contact wall surface portion (ce); 115: Tapered surface portion; m: Slope; 12: Bottom; 13: Positive electrode terminal (first electrode terminal); 14: Terminal seal; 15: Negative electrode terminal (second electrode terminal); 19: Insulator; 20: Electrode assembly; 21: First electrode; 22: Second electrode; 23: Metal foil; 24: Active material layer; 25: Coated portion; 26: Uncoated portion; 27: Cut tab; 28: Separator; 31: Current collector plate; 32: Terminal connecting part; 33: Ring part; 34: Electrode connecting part; 40: Cap; 41: Electrode connecting part; W: Welding portion; 42: Liquid introduction port; 43: protruding portion; 44: outer surface portion; 45: base surface portion; 46: first inclined surface portion; 47: curved surface portion; P: point where the inclination of the tangent is equal to the first inclination; G: gap;48: Contact surface portion (cf); M: Connection portion; 49: Second inclined surface portion; 50: Stopper; 60: Vent; 70: Battery pack; 71: Casing; 72: Battery cell; 80: Vehicle (automobile); EMBODIMENTS OF THE INVENTION

[0154] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings so that those skilled in the art will be able to easily understand the technical spirit of the present invention. In describing the present invention, a detailed description of the related art related to the present invention will be omitted if it is feared that such a detailed description would unnecessarily obscure the gist of the present invention. Preferred embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. In the drawings, identical reference numerals are used to indicate identical or similar components.

[0155] Expressions such as "first," "second," etc., can be used to describe different elements, and these elements are not restricted by ordinal numbers. These expressions are used only to distinguish one element from another, and unless explicitly stated otherwise, a first element can also be a second element.

[0156] Each item mentioned in the description may be given singly or in plural, unless otherwise stated.

[0157] Hereinafter, expressions such as "arranging an element at an upper portion (or lower portion) of an element" or "arranging an element at a top (or bottom) of an element" are not only limited to "arranging an element to be in contact with an upper surface (or lower surface)", but may also refer to "arranging an element above an upper surface (or lower surface) with another element disposed therebetween".

[0158] Furthermore, when an element is described as being "connected to," "coupled to," or "in contact with" another element, it should be understood that the element may be "directly connected to," "directly coupled to," or "directly in contact with" another element. Alternatively, these expressions may mean that the element may be "connected to," "coupled to," or "in contact with" another element, with yet another element disposed between or over yet another element.

[0159] Furthermore, when an element is described as being "connected to," "coupled to," or "in contact with" another element, it should be understood that the element may be "directly connected to," "directly coupled to," or "directly in contact with" another element. Alternatively, these expressions may mean that the element may be "connected to," "coupled to," or "in contact with" another element, with yet another element disposed between or over yet another element.

[0160] Singular terms used herein include plural terms unless the context expressly dictates otherwise. Terms such as "consists of" or "comprises" used herein should not be construed to necessarily encompass all elements or steps described in the specification, but should be interpreted to mean that some of the elements or steps may not be encompassed, or that additional elements or steps may be encompassed.

[0161] Throughout the description, "A and / or B" refers to A, B, or A and B, unless expressly stated otherwise. Expressions such as "C to D" refer to from equal to or higher than C to equal to or lower than D, unless expressly stated otherwise.

[0162] In the description of the embodiments, the term "axial direction" refers to "a direction along which the axis extending, which forms the winding center of the jellyroll electrode assembly, extends." The term "radial direction" refers to "a direction toward (centripetal) or away (centrifugal) from the axis." The term "circumferential direction" refers to "a direction surrounding the axis."

[0163] The width direction of the electrode assembly in the unwound state corresponds to the axial direction of the jellyroll (in the wound state). The longitudinal direction of the electrode assembly in the unwound state corresponds to the circumferential direction of the jellyroll.

[0164] In the following, a cylindrical battery cell according to an embodiment of the present invention will be described with reference to the Fig. 2 to Fig. 13 described.

[0165] The battery cell of the embodiment may, for example, be a cylindrical battery cell whose form factor ratio (defined as the diameter of the cylindrical battery cell divided by the height, ie, the ratio of the diameter Φ to the height H) is greater than about 0.4.

[0166] Here, the form factor refers to values ​​that represent the diameter and height of a cylindrical battery cell. The cylindrical battery cell to be applied to the pressure tester can be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the values ​​representing the form factor, the first two numbers represent the diameter of the cell, the next two numbers represent the height of the cell, and the last number, 0, represents that the cross-section of the cell is circular.

[0167] The battery cell to be applied to the pressure tester may be a cell that is approximately cylindrical with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0168] A battery cell according to another embodiment may be a cell that is approximately cylindrical with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0169] A battery cell according to yet another embodiment may be a cell that is approximately cylindrical with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.436.

[0170] A battery cell according to yet another embodiment may be a cell that is approximately cylindrical with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0171] A battery cell according to another embodiment may be a cell that is approximately cylindrical with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0172] The pressure tester of the present invention can obviously be applied to battery cells with a form factor ratio of approximately 0.4 or less, for example, 18650 cells, 21700 cells, etc. For an 18650 cell, its diameter is approximately 18 mm, its height is approximately 65 mm, and the form factor ratio is 0.277. For a 21700 cell, its diameter is approximately 21 mm, its height is approximately 70 mm, and the form factor ratio is 0.300.

[0173] With reference to Fig. 2 and Fig. 10, a battery housing 10 has a cylindrical side wall 11 and a bottom 12 which is connected to an axial end of the side wall 11.

[0174] The bottom 12 and the side wall 11 can be manufactured by forming a metal foil with a nickel-plated steel surface through a deep drawing process and performing a trimming process on the side wall 11 with a punch while holding the front end of the side wall with a blank holder. However, the material of the battery case 10 is not limited to this.

[0175] A hole may be provided at the center of the bottom 12, and a first electrode terminal 13 may be fitted into and coupled to the hole. The first electrode terminal 13 may be riveted and fixed to the bottom 12 with a terminal seal 14 interposed therebetween. The terminal seal 14 is interposed between the first electrode terminal 13 and the bottom 12 to seal (tightly close) the interior and exterior of the battery case 10, thereby preventing electrolyte leakage, and to electrically insulate the first electrode terminal 13 and the bottom 12.

[0176] However, the connection method between the first electrode terminal 13 and the base 12 is not limited to this. For example, if the structure can seal between the first electrode terminal 13 and the base 12 and electrically insulate the first electrode terminal 13 and the base 12, various other fastening methods are also applicable, such as a bolt-nut connection method, a glass sealing method, a chromium plating method, and a PP-MAH hot-bonding method.

[0177] The first electrode terminal 13 may have a first polarity, and the battery case 10 may have a second polarity. Thus, the bottom 12 of the battery case 10 and the side wall 11 connected thereto may all have the second polarity.

[0178] Thus, the battery case 10 may have both the first electrode terminal 13 and the second electrode terminal 15 arranged at one axial end thereof. Consequently, the battery case 10 may have both a bus bar connected to the first electrode terminal 13 and a bus bar connected to the second electrode terminal 15 arranged at one axial end thereof, i.e., at the top of the battery case 10.

[0179] In one example, the first electrode terminal 13 may be a cathode terminal, and the second electrode terminal 15 may be an anode terminal. Or the polarities may be reversed.

[0180] The electrode assembly 20 is accommodated in the battery case 10. The electrode assembly 20 is formed by preparing a first electrode 21, a second electrode 22, and separators 28 extending in a longitudinal direction with a predetermined width, as shown in Fig. 3, by forming a laminate by sequentially stacking the first electrode 21, the separator 28, the second electrode 22 and the separator 28 as shown in Fig. 4 and Fig. 5, and then winding the laminate so that it has a shape of a jellyroll wound around the core axis.

[0181] The first electrode 21 can be a cathode and the second electrode 22 can be an anode. Or the polarities can be reversed.

[0182] The first electrode 21 and the second electrode 22 are each manufactured in the form of a foil. The electrode foil is produced by applying an active material layer 24 to the surface of a metal foil 23. The electrode foil comprises a coated region 25 where the active material layer 24 is applied, and an uncoated region 26 where the active material layer 24 is not applied (or no active material layer is applied). The anode foil is provided with an uncoated region 26 on one side in the width direction, and the cathode foil is provided with an uncoated region 26 on the other (opposite) side in the width direction.

[0183] The uncoated area 26 is exposed or protrudes from the laminate in the width direction. The uncoated area 26 itself functions as an electrode tab.

[0184] Notches (cuts) may be formed at predetermined intervals in the uncoated area 26 to form cut tabs 27 each in the shape of a flag.

[0185] In the embodiment, the notched tabs 27 are illustrated in the shape of an equilateral trapezoid. However, the notched tabs 27 may have various shapes, such as semicircular, semi-elliptical, triangular, rectangular, parallelogram, etc.

[0186] Additionally, in the embodiment, the cut-out tabs 27 having the same width arranged in the longitudinal direction are exemplary. However, the width of the cut-out tabs may gradually widen from the core side to the outer peripheral side.

[0187] Furthermore, in the embodiment, the height of the notched tabs 27 gradually increases from the core side to the outer peripheral side. However, the height of the notched tabs may be constant or gradually decrease.

[0188] Furthermore, in the embodiment, a structure is exemplified in which the cut tabs 27 are removed at predetermined portions of the centripetal end and the distal end of the uncoated portion 26. However, it should be understood that the cut tabs may not be removed from the centripetal end of the uncoated portion, and the cut tabs may not be removed from the distal end of the uncoated portion.

[0189] In the jellyroll-shaped electrode arrangement 20, the notched tabs 27 may be bent and flattened in the radial direction, as in Fig. 4. The notched tabs 27 can be bent radially inward or outward. In the embodiment, a structure is illustrated in which the notched tabs 27 are bent radially inward.

[0190] The cut tabs 27 can be bent sequentially in the process of forming the jellyroll-shaped electrode assembly 20 by winding the laminate. Alternatively, the cut tabs 27 can be formed by bending them all at once after winding the laminate to form a jellyroll-shaped electrode assembly.

[0191] The notched tabs 27 of the first electrode 21 and the notched tabs 27 of the second electrode 22, which are bent and overlapped in the radial direction as described above, can provide a plane that is substantially perpendicular to the axial direction at each of two axial ends of the electrode assembly 20, as shown in Fig. 7 shown.

[0192] A current collector plate 31 may be connected to the substantially flat surface provided by bending the cut-out tab 27 exposed at the two axial ends of the electrode assembly 20, as shown in Fig. 8 shown.

[0193] The current collector plate 31 can be manufactured by punching (stamping), trimming, piercing and bending a metal foil.

[0194] With reference to Fig. 8, the current collector plate 31 includes a terminal connecting part 32 extending radially from the center, a ring part 33 connecting the distal edge of the terminal connecting part 32 in the circumferential direction, and an electrode connecting part 34 extending centripetally from the ring part 33 but not connected to the terminal connecting part 32. The center of the terminal connecting part 32 covers at least a portion of the hollow core portion of the electrode assembly 20.

[0195] The electrode connecting part 34 is connected to the cut tabs 27 of the first electrode 21 of the electrode assembly 20 using a method such as laser welding before the electrode assembly 20 is inserted into the battery case 10.

[0196] With reference to Fig. 9, the current collector plate may not be connected to the cut-out tab 27 of the second electrode 22 of the electrode assembly 20. It should be appreciated that the present invention is not limited to a structure in which the current collector plate is not connected to the cut-out tab 27 of the second electrode 22.

[0197] As in Fig. 10 and Fig. As shown in Figure 11, the electrode assembly 20 is housed in the battery case 10 with the current collector plate 31 oriented to face the bottom 12 of the battery case 10. Here, an insulator 19 is disposed between the current collector plate 31 and the bottom 12 of the battery case 10 to electrically insulate the current collector plate 31 and the bottom 12.

[0198] Furthermore, the terminal connecting part 32 of the current collector plate 31 is connected to the first electrode terminal 13 fixed to the battery case 10 by resistance welding, ultrasonic welding, or laser welding. The welding device for welding the current collector plate 31 and the first electrode terminal 13 can perform welding by accessing the back of the center of the terminal connecting part 32 of the current collector plate 31 from the other axial end of the electrode assembly 20 through the hollow core portion of the electrode assembly 20. It should be appreciated that, in addition to the welding method described above, the current collector plate 31 and the first electrode terminal 13 can be connected by brazing or soldering.That is, various connection methods can be used as long as the current collector plate 31 and the first electrode terminal 13 are fixed to each other and electrically connected to each other.

[0199] With reference to Fig. 12 and Fig. 13, when the electrode assembly 20 is housed in the battery case 10 and the first electrode 21 is connected to the first electrode terminal 13, the cut-out tab 27 of the second electrode 22 can be directly connected to the cap 40, which is press-fitted through the open end of the battery case 10. Thus, the second electrode 22 is electrically connected to the cut-out tab 27 and the welding portion W of the cap 40. It will be appreciated that, in addition to welding, other joining methods such as brazing or soldering can be applied to the cut-out tab 27 and the cap 40.

[0200] The edge of the cap 40 is electrically connected to the side wall 11 of the battery case 10, sealed, and secured. Thus, the second electrode 22 can be electrically connected to the cap 40 and the battery case 10. Various methods such as welding, brazing, and soldering can be used to electrically connect and seal the connection area m of the cap 40 and the battery case 10.

[0201] The cap 40 and its assembly process, which is described in the Fig. 10 to Fig. 14 are illustrated by way of example, and various embodiments of the structure of the cap 40 and their assembly methods will be described below. Although joining by welding is exemplary in an embodiment described below, the present invention is not limited thereto. FIRST EMBODIMENT

[0202] In the following, the cap according to a first embodiment and the structure of a battery cell with the attached cap will be described with reference to Fig. 14 to Fig. 21 described.

[0203] The cap 40 can be manufactured by forming a circular metal foil using a press.

[0204] The cap 40 has a substantially disc shape to cover the open end of the battery case 10. The cap 40 according to the first embodiment includes, in order from the radially outer side to the inner side, a contact surface portion 48, a curved surface portion 47, a first inclined surface portion 46, a base surface portion 45, a second inclined surface portion 49, and an electrode connecting part 41.

[0205] The contact surface portion 48 is provided on the radially outer edge of the cap 40 and extends in the axial direction such that its outer peripheral surface is in contact with the inner periphery of the side wall of the battery case 10. The contact surface portion 48 extends from the axially outer side to the axially inner side. The outer peripheral surface of the contact surface portion 48 may have a cylindrical surface.

[0206] The curved surface portion 47 is connected to the lower end portion of the contact surface portion 48 of the cap 40, that is, the axially inner end of the contact surface portion 48, and has a downwardly convex cross section extending radially inward toward the axially inner side. The inclination of the tangent of the curved surface portion 47 gradually becomes gentler the farther it is from the contact surface portion 48. Since the contact surface portion 48 extends parallel to the axial direction, the inclination of the tangent of the outer peripheral surface of the curved surface portion 47 can gradually decrease from 90 degrees the farther it is from the contact surface portion 48.

[0207] The curved surface portion 47 may extend to a point where the inclination of the tangent is 0 degrees. The point where the inclination of the tangent of the curved surface portion 47 is 0 degrees may be the innermost portion of the curved surface portion 47 in the axial direction. More preferably, the curved surface portion 47 may extend beyond 0 degrees to an angle where the inclination of the tangent is equal to the inclination of the first inclined surface portion 46.

[0208] The first inclined surface portion 46 is provided between the curved surface portion 47 and the base surface portion 45. The first inclined surface portion 46 has a substantially constant inclination equal to the second inclination and extends axially outward toward a radially inner side. In the embodiment, the second inclination of approximately 30 degrees is exemplary. As a result, the angle between the first inclined surface portion 46 and the contact surface portion 48 can be approximately 60 degrees.

[0209] The cap 40 is provided with a base surface portion 45 that extends horizontally at a location radially further inward than the curved surface portion 47. The base surface portion 45 is connected to the radially inner end of the first inclined surface portion 46 and can extend horizontally inward from the connecting portion in the radial direction.

[0210] Since the surface of the base surface portion 45 has a flat ring shape, the base surface portion 45 serves as a foot (a support) for the battery cell when the battery cell is in an upright orientation with the cap 40 placed on the ground, as shown in Fig. 2 shown.

[0211] With reference to Fig. 20, the axial outer side surface d of the base surface portion 45 is arranged further outward in the axial direction than the axial outer end c of the contact surface portion 48. Therefore, as in Fig. 2, even when the battery cell is in an upright orientation with the cap 40 placed on the ground, the welding area of ​​the cap 40 and the casing 10 is prevented from directly contacting the ground, thereby protecting the welding area.

[0212] The cap 40 is provided with an electrode connecting part 41 extending horizontally to a position radially further inward than the base surface portion 45. Referring to Fig. 20, the axial inner surface a, ie, the bottom surface, of the electrode connecting part 41 is arranged further inward in the axial direction than the axial inner end b of the curved surface portion 47, ie, the point where the inclination is 0.

[0213] Thus, the cap 40 can be press-fitted into the battery case 10 until the bottom surface (axial inner surface) of the electrode connecting part 41 comes into close contact with the tab of the second electrode 22 of the electrode assembly 20 housed in the case 10. That is, according to the embodiment, the press-fit depth of the cap 40 into the battery case 10 can be regulated by interference or contact between the electrode connecting part 41 and the tab of the second electrode 22 of the electrode assembly 20 housed in the battery case 10.

[0214] The electrode connecting part 41 can be in close contact with the tab of the second electrode 22 of the electrode assembly 20 to be connected to each other. The connection can be accomplished by welding. The welding portion W of the electrode connecting part 41 and the tab 27 of the second electrode 22 are formed by a laser irradiated from the axial outer side onto the axial outer side surface of the electrode connecting part 41. The laser can be irradiated in a scanning manner along the radial direction to form the welding portion W extending in the radial direction.

[0215] As described above, the cap 40 functions as a cover that closes the open end of the battery case 10 and also as a current collector plate for the second electrode 22. Thus, the cap 40 may have a second polarity, and the side wall 11 welded thereto and the bottom 12 connected thereto may also have the second polarity.

[0216] The electrode connecting part 41 can extend radially outward by more than 1 / 2 the radius of the battery housing 10. Preferably, the electrode connecting part 41 can extend by more than 0.7 times the radius of the battery housing 10. The electrode connecting part 41 can extend flat in the radial direction.

[0217] Since the electrode connecting part 41 of the cap 40 according to the first embodiment has a flat ring shape with a sufficient radius, a sufficient welding area with the tab of the second electrode 22 can be secured.

[0218] A structure in which the tab of the second electrode 22 is electrically connected to the electrode connecting part 41 of the cap 40 by welding without a separate current collector plate is exemplified in the first embodiment. However, the present invention does not preclude the use of an additional current collector plate. That is, it can be appreciated that the current collector plate may be welded to the tab of the second electrode 22, and the electrode connecting part 41 of the cap 40 may be welded to the current collector plate. That is, an arrangement structure in which a flat current collector plate is arranged between the bottom surface of the electrode connecting part 41 and the tab of the second electrode 22 is also applicable.

[0219] Between the base surface portion 45 and the electrode connecting part 41, a second inclined surface portion 49 is provided, which extends radially inward toward the axial inner side and has a substantially constant third inclination. According to the embodiment, the third inclination of approximately 75 degrees is exemplary. The second inclination of the first inclined surface portion 46 may be smaller than the third inclination of the second inclined surface portion 49. That is, the second inclined surface portion 49 may be steeper than the first inclined surface portion 46. Thus, the length of the base surface portion 45 and the electrode connecting part 41 in the radial direction can be secured as much as possible.

[0220] In this case, a contact wall surface portion 113 is provided at the open end of the battery case 10 where the inner diameter of the side wall 11 widens.

[0221] A press-fit guide surface portion 111 that guides the insertion of the cap 40 may be provided on the axially outer end corner of the inner peripheral surface of the contact wall surface portion 113. While the rounded, throat-shaped press-fit guide surface portion 111 is exemplary, the press-fit guide surface portion 111 may have a chamfer shape.

[0222] The contact wall surface portion 113 can be formed by applying pressure to the edge of the inner peripheral surface of the side wall 11.

[0223] The inner peripheral surface of the contact wall surface portion 113 may have a cylindrical surface.

[0224] The outer diameter of the contact surface portion 48 may be equal to the inner diameter of the contact wall surface portion 113. To ensure adhesion between the two surfaces, the outer diameter of the contact surface portion 48 may be slightly larger than the inner diameter of the contact wall surface portion 113. Thus, when the cap 40 is press-fitted into the open end of the battery case 10, the contact wall surface portion 113 and the contact surface portion 48 can come into strong, close contact in the radial direction.

[0225] The curved surface portion 47, the first inclined surface portion 46 and the second inclined surface portion 49, which are connected to the radially inner side of the contact surface portion 48 of the cap 40, form a cross-sectional shape capable of elastic deformation of the cap 40 radially inward.

[0226] In particular, when the contact surface portion 48 of the cap 40 receives a force inward in the radial direction, as in Fig. 18, elastic deformation of the curved surface portion 47 is induced such that elastic deformations of a portion connecting the first inclined surface portion 46 and the base surface portion 45, a portion connecting the base surface portion 45 and the second inclined surface portion 49, and a portion connecting the second inclined surface portion 49 and the electrode connecting part 41 are uniformly induced.

[0227] Thus, while the deformations of the portion of the contact surface portion 48 extending parallel to the axial direction and the portions of the base surface portion 45 and the electrode connecting part 41 extending parallel to the radial direction are kept to a minimum, the curvature of the curved surface portion 47, the internal angle between the contact surface portion 48 and the first inclined surface portion 46, the internal angle of the portion connecting the first inclined surface portion 46 and the base surface portion 45, the internal angle of the portion connecting the base surface portion 45 and the second inclined surface portion 49, and the internal angle of the portion connecting the second inclined surface portion 49 and the electrode connecting part 41 are reduced.

[0228] As a result, the adhesion in the radial direction between the contact surface portion 48 and the contact wall surface portion 113 can be secured without deformation that deteriorates the roundness by twisting or bending the cap 40 or the side wall 11 of the battery case 10.

[0229] With reference to Fig. 20, the axial length cf of the contact surface portion 48 is shorter than the axial length ce of the contact wall surface portion 113. In addition, there is a portion in which the inner diameter of the portion connecting the side wall 11 and the contact wall surface portion 113 changes.

[0230] A tapered surface portion 115 having a substantially constant first inclination m and extending radially inward toward an axial inner side may be provided between the inner peripheral surface of the side wall 11 and the inner peripheral surface of the contact wall surface portion 113. In the embodiment, the first inclination m of approximately 45 degrees is exemplary.

[0231] The tapered surface portion 115 may be formed even when the contact wall surface portion 113 is formed.

[0232] Accordingly, the curved surface portion 47 connected to the axial inner end of the contact surface portion 48 is convex downward, with the inclination of the tangent of the outer peripheral surface thereof gradually decreasing the farther it is from the contact surface portion 48.

[0233] With reference to Fig. 21, on the outer peripheral surface of the curved surface section 47, there is the point P where the inclination of the tangent is equal to the first inclination m, ie an angle of 45 degrees.

[0234] The point P where the inclination of the tangent to the outer peripheral surface of the curved surface portion 47 is equal to the first inclination m may be located radially further inward than the tapered surface portion 115. Thus, the inclination of the portion of the curved surface portion 47 facing the tapered surface portion 115 in the axial direction is greater than the first inclination m of the tapered surface portion 115, as shown in Fig. 21 shown.

[0235] Therefore, even if the outer peripheral surface of the curved surface portion 47 is aligned with the lower end portion (g: see Fig. 20) of the tapered surface portion 115 is in contact due to manufacturing tolerances of the cap 40 or the battery case 10 or excessive insertion of the cap 40 into the open end of the battery case 10, the curved surface portion 47 may be elastically deformed to be further pressed in beyond the lower end portion g because the inclination of the portion of the curved surface portion 47 in contact with the lower end portion is greater than the first inclination m of the tapered surface portion 115. That is, the tapered surface portion 115 does not regulate the insertion depth of the cap 40.

[0236] In addition, the point P of the curved surface section 47 is located axially further inward than the tapered surface section 115. Thus, as in Fig. 22, the inclination of the portion of the curved surface portion 47 facing the tapered surface portion 115 is greater than the first inclination m of the tapered surface portion 115.

[0237] The axial outer edge of the inner peripheral surface of the contact wall surface portion 113 and the axial outer edge of the outer peripheral surface of the contact surface portion 48 (see c in Fig. 20) are welded by laser L, which is irradiated in the axial direction. The laser radiation direction can be parallel to the axial direction.

[0238] Consequently, even if the laser reaches the tapered surface portion 115 through a fine gap existing between the contact wall surface portion 113 and the contact surface portion 48, the laser is reflected by the tapered surface portion 115 and the curved surface portion 47 facing the tapered surface portion 115 to change its direction back to the axial outside.

[0239] Therefore, the depth of press-fitting the cap 40 by the electrode connecting part 41 instead of the tapered surface portion 115 is such that the laser does not reach a gap G between the boundary between the tapered surface portion 115 and the side wall 11 and the curved surface portion 47, and the laser disappears by the repeated reflections in the space between the tapered surface portion 115 and the curved surface portion 47.

[0240] Thus, in the structure of the battery cell having the cap 40 and the battery case 10 according to the first embodiment applied thereto, the joining process of the battery case 10 and the cap 40 can be prevented from affecting the electrode assembly 20 accommodated in the battery case 10.

[0241] Furthermore, as described above, the height b of the lower end portion of the curved surface portion 47 is higher than the height a of the bottom surface of the electrode connecting part 41, and the height of the bottom surface of the electrode connecting part 41 is equal to that of the tab 27 of the second electrode of the electrode assembly. Therefore, the lower end portion of the curved surface portion 47 is spaced apart from the upper end portion of the electrode assembly in the axial direction. Consequently, even if heat is conducted from the junction of the cap 40 and the battery case 10 to the curved surface portion 47 of the cap 40, the influence of the conducted heat on the electrode assembly 20 can be minimized.

[0242] The lower end portion of the curved surface portion 47 being spaced apart from the upper end portion of the electrode assembly and the upper end portion of the tab 27 of the second electrode of the electrode assembly in the axial direction means that the insertion depth of the cap 40 is not regulated by the interference between the curved surface portion 47 and the electrode assembly 20.

[0243] In addition, even if the outer peripheral surface of the curved surface portion 47 is in contact with the radially inner end of the tapered surface portion 115, since the insertion of the cap 40 is excessively designed due to manufacturing tolerances or assembly errors, elastic deformation of the curved surface portion 47 with the steep inclination of the tangent is induced at the contact area, thereby preventing the insertion depth of the cap 40 from being regulated despite manufacturing tolerances or assembly errors.

[0244] According to the embodiment, when the cap 40 is press-fitted into the battery case 10, the press-fit depth of the cap 40 is regulated by the electrode connecting part 41, since the bottom surface (a: see Fig. 20) of the electrode connecting part 41, which is arranged further inward in the axial direction than the axial inner end (b: see Fig. 20) of the curved surface portion 47, first comes into contact with the tab 27 of the second electrode 22 of the electrode arrangement 20.

[0245] Therefore, the cap 40 can be pressed in to a depth at which the axial inner surface of the electrode connecting part 41 comes into close contact with the tab 27 of the second electrode 22 of the electrode assembly 20 accommodated in the housing 10.

[0246] Consequently, the electrode connecting part 41 can be in close contact with the tab of the second electrode 22 by press-fitting the cap 40. The electrode connecting part 41 and the notched tab 27 can be welded while being in close contact with each other in the axial direction.

[0247] The welding of the electrode connecting part 41 and the second electrode tab 27 can be performed by a laser irradiated onto the axial outer side surface of the electrode connecting part 41 from the axial outer side, as shown in Fig. 19. Local heat generated by the laser irradiated onto the surface of the electrode connecting part 41 can melt and bond the surface of the cut tab 27 in contact with the electrode connecting part 41 and the bottom surface thereof.

[0248] As in Fig. As shown in Figure 19, the laser beam moves in the radial direction and is irradiated onto the electrode connecting part 41. Thus, the welding portion W of the electrode connecting part 41 extends in the radial direction. The welding portion W may be arranged radially and may be arranged at a plurality of equal intervals along the circumferential direction.

[0249] The welding section W extends in the radial direction, and thus the electrode connecting part 41 can be connected to all of the notched tabs 27 of the second electrode 22 arranged from the outer peripheral side to the core side of the electrode assembly. Such a welding line widens the current path, thereby greatly reducing the internal resistance of the second electrode.

[0250] When the cap 40 described above is attached, the connection area between the cap 40 and the battery case 10 can be made simple, the number of parts and the assembly time can be reduced, and the energy density can be increased by securing more internal volume because the current collector plate is not required when electrically connecting the tab of the second electrode 22 to the battery case 10.

[0251] The cap 40 according to the first embodiment does not have a liquid introduction port 42 according to the second embodiment, which will be described later.

[0252] Hereinafter, a manufacturing method of a cylindrical battery cell using the cap 40 according to the first embodiment will be described with reference to Fig. 42. However, since the manufacturing process has already been described previously, the process is described below in abbreviated form.

[0253] First, a battery case 10 having a first electrode terminal 13 fixed to a bottom 12 is prepared, and a jellyroll-shaped electrode assembly 20 having a first electrode 21 and a second electrode 22 is prepared.

[0254] Thereafter, the electrode assembly 20 is received in the battery case 10, with a tab of the first electrode 21 and a current collector plate 31 of the electrode assembly 20 facing the bottom 12.

[0255] Thereafter, the first electrode 21 is connected to the first electrode terminal 13 and electrically connected.

[0256] The electrolyte solution is then introduced into the battery housing 10.

[0257] When the introduction of the electrolyte solution is completed, the cap 40 is press-fitted into the open end of the battery case 10 to connect the electrode connecting part 41 of the cap 40 and the second electrode 22 of the electrode assembly 20 so that the electrode connecting part 41 of the cap 40 and the second electrode 22 of the electrode assembly 20 are in close contact with each other and the contact wall surface portion 113 of the battery case 10 and the contact surface portion 48 of the cap 40 are connected and electrically connected to each other. SECOND EMBODIMENT

[0258] In the following, a cap and a battery cell with the cap attached thereto according to a second embodiment are described with reference to Fig. 23 to Fig. 27. In the description of the second embodiment, descriptions that overlap with the first embodiment may be omitted. Therefore, contents of one embodiment that are omitted from the description can be understood from the contents of other embodiments. Furthermore, it should be understood that replacement, addition, or omission between the configurations of one embodiment and another embodiment is also possible.

[0259] The cap 40 according to the second embodiment is further provided with a liquid introduction opening 42 in the central portion of the cap 40 compared to the first embodiment. When the open end of the battery case 10 is covered with the cap 40, the liquid introduction opening 42 can be aligned with the hollow core portion of the electrode assembly 20 housed in the battery case 10.

[0260] The liquid introduction port 42 may be provided at the lower portion of the cap 40, that is, at the protruding portion 43, which protrudes slightly upward compared to the electrode connecting part 41 of the cap 40. The height of the protruding portion 43 is set to be lower than that of the base surface portion 45. The protruding portion 43 is connected to the centripetal edge of the electrode connecting part 41 and widens outward in the axial direction the closer it is to the centripetal axis.

[0261] The liquid inlet opening 42 can be closed by covering it with the stopper 50. The edge of the liquid inlet opening can be sealed (tightly closed) with the edge of the stopper 50. Sealing can be accomplished by seam welding or other known sealing methods.

[0262] When the liquid introduction port 42 is covered with the stopper 50, the height of the stopper 50 may also be lower than that of the base surface portion 45. Since the stopper 50 is also lower than the base surface portion 45, the stopper 50 is not subjected to direct load even when the battery cell is in an upright orientation with the cap 40 in contact with the ground.

[0263] The protruding portion 43 protrudes higher than the lower portion of the cap, that is, the electrode connection part. Thus, the edge portion of the liquid introduction port is spaced apart from the tab 27 of the second electrode. Therefore, the influence of the joining process of the stopper 50 on the battery performance, such as damage to the separator caused by joining heat conducted to the electrode assembly 20 after the electrolyte solution is introduced through the liquid introduction port 42, the liquid introduction port 42 is covered with the stopper 50, and the joining by welding, etc., can be minimized.

[0264] The cap 40 according to the first embodiment does not have a liquid introduction opening. Thus, during the manufacturing process of a battery cell with the cap 40 according to the first embodiment, the electrolyte solution introduction process can be performed first before the battery case 10 is covered with the cap 40, since there is no liquid introduction opening at the bottom 12 of the battery case 10.

[0265] However, when the liquid introduction port 42 is provided in the cap 40 as in the second embodiment, the electrolyte solution can be introduced through the liquid introduction port 42 even after the cap 40 is press-fitted into the battery case 10 and the welding portion W and the joining region M are formed. Furthermore, if the stopper 50 is joined to the edge of the liquid introduction port 42 while the protruding portion 43 protrudes upward, the risk of the electrolyte solution being affected by the joining heat of the stopper 50 can be reduced.

[0266] At this time, the liquid introduction port 42 provided in the center of the cap 40 may be a passage through which equipment for welding the first electrode terminal 13 and the current collector plate 31 of the first electrode 21 enters and exits.

[0267] Therefore, even after connecting the cap 40 to the battery case 10, the welding equipment can penetrate into the battery case 10 through the liquid introduction port 42 to connect the first electrode 21 and the first electrode terminal.

[0268] Hereinafter, a manufacturing method of a cylindrical battery cell using a cap 40 provided with a liquid introduction port 42 according to the second embodiment will be described with reference to Fig. 43. However, since the manufacturing process has already been described previously, the process is described below in abbreviated form.

[0269] First, a battery case 10 having a first electrode terminal 13 fixed to a bottom 12 is prepared, and a jellyroll-shaped electrode assembly 20 having a first electrode 21 and a second electrode 22 is prepared.

[0270] Thereafter, the electrode assembly 20 is received in the battery case 10, with a tab of the first electrode 21 and a current collector plate 31 of the electrode assembly 20 facing the bottom 12.

[0271] Thereafter, the first electrode 21 is connected and electrically connected to the first electrode terminal 13, the cap 40 is press-fitted into the open end of the battery case 10 to connect the electrode connecting part 41 of the cap 40 and the tab 27 of the second electrode 22 of the electrode assembly 20 by bringing them into close contact, and the contact wall surface portion 113 of the battery case 10 is connected and electrically connected to the contact surfaces 48 of the cap 40.

[0272] Here, the cap 40 can be pressed into the open end of the battery case 10 after the first electrode 21 has been connected to the first electrode terminal 13. Alternatively, the cap 40 can first be pressed into the open end of the battery case 10, and then the first electrode 21 can be connected to the first electrode terminal 13 through the liquid introduction port 42.

[0273] Thereafter, the electrolyte solution is introduced into the battery case 10 through the liquid introduction port 42, and the liquid introduction port 42 is covered with a stopper 50 and connected by a method such as welding after the introduction of the electrolyte solution is completed. Various sealing and fastening methods can be used to connect the protruding portion 43 at the edge of the liquid introduction port 42 and the stopper 50.

[0274] In this case, the cap 40 can be connected to the tab of the second electrode 22 of the electrode assembly 20 before the electrode assembly 20 is received in the battery housing 10, as shown in Fig. 27. Thus, the cap 40, which is connected to the electrode assembly 20, can be inserted into the battery case 10 when the electrode assembly 20 is received in the battery case 10.

[0275] That is, when the current collector plate 31 is connected to the tab of the first electrode 21 of the electrode assembly 20 and the cap 40 is connected to the tab of the second electrode 22, the electrode assembly 20 can be housed in the battery case 10. Furthermore, welding between the current collector plate 31 and the first electrode terminal 13 can be performed through the liquid introduction port 42 of the cap 40 and the hollow core portion of the electrode assembly 20.

[0276] In the following, a manufacturing method of a cylindrical battery cell is described with reference to Fig. 44 in the same manner as described above. However, since the manufacturing process has already been described previously, the procedure is described below in abbreviated form.

[0277] First, a battery case 10 having a first electrode terminal 13 fixed to a bottom 12 is prepared, and a jellyroll-shaped electrode assembly 20 having a first electrode 21 and a second electrode 22 is prepared.

[0278] Thereafter, the first electrode 21 and the current collector plate 31 are connected and joined at one axial end of the electrode assembly 20, and the second electrode 22 and the cap 40 are connected and joined at the other axial end.

[0279] Thereafter, the cap 40 is pressed into the open end of the battery case 10, wherein the electrode assembly 20 is received in the battery case 10, while the tab of the first electrode 21 and the current collector plate 31 of the electrode assembly 20 face the bottom 12.

[0280] Thereafter, a process of connecting and electrically connecting the first electrode 21 to the first electrode terminal 13 and a process of connecting and electrically connecting the battery case 10 and the cap 40 are performed.

[0281] Thereafter, the electrolyte solution is introduced into the battery case 10 through the liquid introduction port 42, and the liquid introduction port 42 is then covered and closed with a stopper 50.

[0282] As described above, the manufacturing method can be configured in various ways when the manufacturing of a battery cell with the cap 40 equipped with the liquid introduction port 42 is applied. THIRD EMBODIMENT

[0283] In the following, a cap and a battery cell with the cap attached thereto according to a third embodiment will be described with reference to Fig. 28 to Fig. 33 described.

[0284] The cap 40 according to the third embodiment differs from the first embodiment in the structure of the electrode connecting part 41.

[0285] The electrode connecting part 41 according to the first embodiment described above has a flat disc shape, and a plurality of welding portions W extending in the radial direction are radially arranged on the electrode connecting part 41.

[0286] That is, the cap 40 according to the third embodiment has a plurality of electrode connecting parts 41 which are recessed toward the inside of the battery case 10 and extend in the radial direction.

[0287] The electrode connecting part 41 can be formed by molding the metal foil using a press.

[0288] The plurality of electrode connecting parts 41 may be arranged radially with respect to the center of the cap 40 and may be arranged at equal intervals in the circumferential direction.

[0289] A pair of electrode connecting parts 41 facing each other with respect to the center of the cap 40 are arranged along a line. Four electrode connecting parts 41 provided at 90-degree intervals are exemplary in the third embodiment.

[0290] When a plurality of electrode connecting parts 41 are formed as described above, an outer surface portion 44, which protrudes axially further outward than the electrode connecting part 41, is provided between two circumferentially adjacent electrode connecting parts 41. The outer surface portion 44 may be connected to the radially inner side of the base surface portion 45.

[0291] A projection height of the outer surface portion 44 may be equal to or lower than that of the base surface portion 45.

[0292] The third embodiment exemplifies that the protrusion height of the outer surface portion 44 is equal to that of the base surface portion 45, which forms a single plane. Consequently, when the battery case 10 is placed with the cap 40 of the battery case 10 facing the ground, the outer surface portion 44 can also be in contact with the ground together with the base surface portion 45.

[0293] When the outer surface portion 44 is lower than the base surface portion 45, the base surface portion 45 may provide an annular support surface.

[0294] The bottom surface of the electrode connecting part 41 is in close contact with and connected to the cut-out tab 27 of the second electrode 22 of the electrode assembly 20. The electrode connecting part 41, which is formed by pressing a metal foil, can have a thickness slightly thinner than the thickness of the metal foil before pressing. Thus, when a laser is irradiated onto the surface of the electrode connecting part 41, the local heat generated by the laser can melt and bond the electrode connecting part 41 and the surface of the cut-out tab 27 in contact with the bottom surface of the electrode connecting part 41.

[0295] The electrode connecting part 41 extends in the radial direction, and a welding portion W for connecting the electrode connecting part 41 to the cut-out tab 27 of the second electrode 22 of the electrode assembly 20 may have a welding line shape formed in the radial direction to correspond to the extending direction of the electrode connecting part 41.

[0296] According to the embodiment, a line-shaped welding portion W extending in the radial direction is formed for each of the plurality of electrode connecting parts 41.

[0297] The outer surface portion 44 is arranged between two circumferentially adjacent electrode connecting parts 41 at a position that protrudes further than the electrode connecting part 41.

[0298] Thus, when the electrode connecting part 41 and the notched tab 27 are in close contact by applying pressure to the outer surface portion 44 with a jig on two sides of the electrode connecting part 41 along the circumferential direction, a laser can be irradiated onto the surface of the electrode connecting part 41 to weld the electrode connecting part 41 and the notched tab 27. Consequently, welding can be reliably performed because the pressure of the jig brings the electrode connecting part 41 into close contact with the notched tab 27 along the longitudinal direction of the weld line on both sides of the weld line.

[0299] A pair of electrode connecting parts 41, which are opposite to each other with respect to the center of the cap 40, are arranged on a straight line passing through the center of the cap 40. Thus, when forming a welding line, the welding line of the two electrode connecting parts 41 arranged along a line (straight line) can be formed with only one movement of the laser welding machine. Assuming that the first electrode connecting part, the second electrode connecting part, the third electrode connecting part, and the fourth electrode connecting part according to the first embodiment are sequentially arranged on the cap 40 along the circumferential direction thereof, for example, the first electrode connecting part and the third electrode connecting part can be welded at once, and the second electrode connecting part and the fourth electrode connecting part can be welded at once.

[0300] In addition, according to the embodiment, when pressure is applied to the outer surface portion 44 provided on two sides of the first electrode connecting part and the third electrode connecting part, which are arranged along a line with respect to the center of the cap 40 with a jig, the cap 40 can behave as a rigid body without being twisted or bent despite the pressure of the jig due to the large secondary moment of inertia provided by the depressed shape of the second electrode connecting part and the fourth electrode.

[0301] According to the embodiment, by providing the four electrode connecting parts 41 as described above, all four electrode connecting parts 41 can be welded with two laser scanning tracks.

[0302] If the number of processed electrode connecting parts 41 is too high, the strength of the cap 40 made of metal foil may be weakened. In addition, if only two or three electrode connecting parts 41 are formed, it is difficult to design a cross-section to ensure a sufficient secondary moment of inertia along the circumferential direction.

[0303] According to the embodiment, when four electrode connecting parts 41 formed on the cap 40 have a "+" shape, the welding process can be performed accurately and easily, the torsion and bending resistance of the cap 40 can also be ensured, and deterioration of the strength of the cap 40 due to the molding process can be prevented. Consequently, the cap 40 according to the third embodiment can have sufficient welding strength with the second electrode 22 through the plurality of electrode connecting parts 41.

[0304] In addition, the load applied to the plurality of outer surface portions 44 in contact with the ground, which are provided along the circumferential direction between the electrode connecting parts 41, acts in a direction in which pressure is applied to the tab of the second electrode 22 and the electrode connecting part 41. This further enhances the protective effect of the weld portion W of the cap 40 and the cut-out tab 27. FOURTH EMBODIMENT

[0305] In the following, a cap and a battery cell with the cap attached thereto according to a fourth embodiment will be described with reference to Fig. 34 to Fig. 41 described.

[0306] First, the cap according to the fourth embodiment differs from the second embodiment in the structure of the electrode connecting part 41. In addition, the cap according to the fourth embodiment differs from the third embodiment in that a liquid introduction port 42 is provided in the central portion of the cap 40.

[0307] The outer surface portion 44 of the cap 40 according to the fourth embodiment protrudes axially further outward than the protruding portion 43 defining the liquid introduction port 42. Furthermore, the protruding portion 43 is directly connected to the outer surface portion 44 in the radial direction.

[0308] Consequently, as in Fig. 38, the phenomenon of joint heat affecting the electrode assembly 20 can be further reduced because a heat conduction path is established in such a manner that the heat generated when the stopper 50 is joined to close the liquid introduction port 42 is not conducted to the electrode assembly but is directly conducted to the outer surface portion 44.

[0309] In addition, as in the cap structure according to the third embodiment, the electrode connecting part 41 is adjacent to the outer surface portion 44 adjacent to the two sides thereof in the circumferential direction, as shown in Fig. 39, such that the heat generated when the electrode connecting part 41 and the metal foil 23 of the second electrode 22 are welded is dissipated through the outer surface portion 44 on the two sides, thereby further reducing the effect of the joining heat on the electrode assembly 20.

[0310] The cap 40 according to the fourth embodiment differs from the first to third embodiments in that the cap 40 further comprises a vent 60.

[0311] The vent 60 is provided radially outward than the electrode connecting part 41 along a circumferential direction. In the fourth embodiment, the vent 60 provided on the base surface portion 45 is exemplary. The vent 60 is formed by processing the two surfaces of the base surface portion 45 into a cut, (structurally) weak portion or thin portion.

[0312] The vent 60 has a predetermined strength that prevents deformation due to the force applied when the cap 40 is press-fitted into the battery case 10, and separates the electrode connecting part 41 of the cap 40 from the contact surface portion 48 of the cap 40 by being damaged when the internal pressure explosively increases due to a short circuit in the battery case 10, etc. Thus, the electrical connection between the electrode connecting part 41 connected to the tab of the second electrode 22 and the battery case 10 is severed, and the interior of the battery case 10 is exposed to the outside, thereby discharging the gas that is the cause of the internal pressure increase.

[0313] The vent 60 may be provided near the central portion of the base surface portion 45 in the radial direction so as to be spaced apart from the first inclined surface portion 46 and the second inclined surface portion 49 in the radial direction.

[0314] As a result, the pressure applied to the base surface portion 45 is transmitted to the first inclined surface portion 46 and the second inclined surface portion 49 and does not affect the vent 60. Therefore, the force applied when the cap 40 is connected to the battery case 10 and the electrode assembly 20 does not deform the vent 60.

[0315] The vent 60 is provided radially further outward than the outer surface portion 44, and the outer surfaces 44 are provided between the electrode connecting parts 41 in the circumferential direction. Furthermore, a space corresponding to the height difference between the outer surface portion 44 and the electrode connecting part 41 is provided on the axial inner side of the outer surface portion 44 (see Fig. 38 etc.).

[0316] Therefore, when the internal pressure of the battery case 10 increases, the pressure is smoothly distributed to the lower space of the outer surface portion 44 located between the electrode connecting parts 41 in the circumferential direction, acting as a force that lifts the outer surface portion 44 upward. In addition, the effect of such a force is concentrated at four locations along the circumferential direction. Therefore, the internal pressure of the battery case 10 can be smoothly transmitted to the vent 60, resulting in a smooth rupture of the vent 60.

[0317] The vent 60 provided in the form of a thin (thinned) portion on the base surface portion 45 is exemplary in the fourth embodiment. However, the vent 60 provided in the cap 40 is not limited thereto. For example, the vent may be provided in the stopper 50 covering the liquid introduction port 42, may be provided in the connected portion of the liquid introduction port 42 and the stopper 50, or may be provided in the connection area M of the cap 40 and the battery case 10.

[0318] That is, according to the embodiment, a venting structure can be implemented in the cap 40 itself or in the connecting area between the cap 40 and other components, so that a separate volume for the venting structure is not required. Therefore, the energy density of the battery cell can be further increased. BATTERY PACK AND VEHICLE

[0319] With reference to Fig. 45, a battery cell 72 having a cap as described above and / or from a manufacturing method as described above may be housed within a housing 71 of a battery pack 70. The battery pack 70 may be constructed using a battery module, which is an intermediate form of assembly, or directly constructed without a battery module, as shown.

[0320] Since the above-described battery cell 72 has a large volume, there is no particular difficulty in implementing the battery pack 70 even without using an intermediate structure called a battery module. Furthermore, since the second electrode of the battery cell 72 is connected by a cap, the battery cell 72 has low internal resistance and high energy density. Since the vent structure 60 is provided in the cap 40 without occupying additional space, the energy density can be further secured. Thus, the energy density of the battery pack 70 including the battery cell 72 can be made even higher.

[0321] The battery pack 70 with such an increased energy density is capable of storing the same amount of energy with reduced volume and weight. When the battery pack 70 with the attached battery cell 72 is mounted on a vehicle, such as the one shown in Fig.46, which uses electricity as an energy source, the range of the vehicle in terms of energy can therefore be further increased.

[0322] It should be understood that the described embodiments are illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the following claims rather than by the detailed description described. The meaning and scope of the claims described later, as well as all changes and modifications derived from the equivalent concept, should be interpreted as being included within the scope of the present invention.

[0323] Although the present invention has been described with reference to the exemplary drawings, it should be understood that the present invention is not limited to the embodiments and drawings disclosed in this specification, and those skilled in the art will recognize that various modifications are possible without departing from the scope and spirit of the present invention. Furthermore, although the operational effects according to the configuration of the present invention are not explicitly described while describing an embodiment of the present invention, it should be recognized that foreseeable effects can also be recognized by the configuration. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] KR 10-2022-0136789

[0001] KR 10-2023-0026204

[0001]

Claims

[1] Battery cell comprising: a battery case 10 having a side wall 11 and an open end provided at one axial end; an electrode assembly 20 provided with a first electrode 21 and a second electrode 22 and received in the battery case 10 in such a manner that a tab 27 of the second electrode 22 faces the open end; and a cap 40 covering the open end of the battery case 10 and connected to the second electrode 22, wherein the side wall 11 is provided with a contact wall surface portion 113 provided at the open end of the battery case 10 and extending outward in the axial direction, wherein an inner peripheral surface of the side wall 11 has a diameter that widens at the contact wall surface portion 113, wherein the cap 40 is provided with: a contact surface portion 48 extending in the axial direction such that an outer peripheral surface thereof is in contact with an inner peripheral surface of the contact wall surface portion 113; and an electrode connection part 41 electrically connected to the tab 27 of the second electrode 22, and wherein an axial outer edge of the inner peripheral surface of the contact wall surface portion 113 and an axial outer edge of the outer peripheral surface of the contact surface portion 48 are connected. [2] The battery cell according to claim 1, wherein an offset of the cap 40 with respect to the battery case 10 is defined by a portion connecting the electrode connecting part 41 of the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 accommodated in the battery case 10. [3] The battery cell according to claim 1 or 2, wherein a length cf of the contact surface portion 48 in the axial direction is shorter than a length ce of the contact wall surface portion 113 in the axial direction. [4] The battery cell according to any one of claims 1 to 3, wherein a portion connecting an inner peripheral surface of the side wall 11 where an inner diameter thereof varies and an inner peripheral surface of the contact wall surface portion 113 does not regulate an insertion depth of the cap 40 with respect to the battery case 10. [5] Battery cell according to one of claims 1 to 4, wherein the cap 40 has a base surface portion 45 which is arranged radially further inward than the contact surface portion 48, wherein the base surface portion 45 extends horizontally in the radial direction, wherein an axial outer side surface of the base surface portion 45 is arranged axially further outward than an axial outer end of the contact surface portion 48, wherein the base surface portion 45 is connected to the contact surface portion 48 by a curved surface portion 47 provided at an axial inner end of the contact surface portion 48, wherein the electrode connecting part 41 is provided at a position which is axially recessed and radially further inward than the base surface portion 45, and wherein an axial inner surface of the electrode connecting part 41 is arranged axially further inward than an axial inner end of the curved surface portion 47, wherein the electrode connecting part 41 is directly connected and electrically connected to the tab 27 of the second electrode 22. [6] The battery cell according to any one of claims 1 to 5, wherein a liquid introduction port 42 is provided at a central portion of the electrode connecting part 41. [7] The battery cell according to any one of claims 1 to 6, wherein the cap has a base surface portion 45 disposed radially further inward than the contact surface portion 48, the base surface portion 45 extending horizontally in the radial direction, and a plurality of electrode connecting parts 41 are provided radially further inward than the base surface portion 45, each of the plurality of electrode connecting parts 41 being recessed toward the inside of the battery case 10 and extending in the radial direction. [8] The battery cell according to claim 7, wherein the plurality of electrode connecting parts 41 are arranged radially with respect to a center of the cap 40. [9] A battery cell according to any one of claims 7 and 8, wherein the plurality of electrode connecting parts 41 are arranged at equal intervals in the circumferential direction. [10] A battery cell according to any one of claims 7 to 9, wherein four electrode connecting parts 41 are provided at 9o-degree intervals. [11] The battery cell according to any one of claims 7 to 10, wherein a pair of electrode connecting parts 41 facing each other with respect to a center of the cap 40 are aligned in a line. [12] The battery cell according to any one of claims 7 to 11, wherein an outer surface portion 44, which projects further outward in the axial direction than the electrode connecting part 41 and is connected to a radially inner side of the base surface portion 45, is provided between two circumferentially adjacent electrode connecting parts 41. [13] The battery cell according to any one of claims 7 to 11, wherein a protruding portion 43 protruding axially further outward than the electrode connecting part 41 is provided at a central portion of the electrode connecting part 41, the protruding portion 43 being provided with a liquid introduction port 42, and the outer surface portion 44 protruding axially further outward than the protruding portion 43. [14] A battery cell according to any one of claims 1 to 13, wherein the cap 40 is provided with a vent 60, and the vent 60 is provided radially further outward than the electrode connecting part 41. [15] Battery cell according to one of claims 1 to 14, wherein the battery case 10 further comprises a bottom 12 connected to the other axial end of the side wall 11, wherein a first electrode terminal 13 is installed on the bottom 12 of the battery case 10 and is electrically insulated from and fixed to the bottom 12, and the first electrode 21 of the electrode assembly 20 is connected to a first electrode terminal 13 through a current collector plate 31 provided at the other axial end of the electrode assembly 20.

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