Cylindrical battery cell, battery pack including the same, and motor vehicle

Abstract

One aspect of the present invention provides a cylindrical battery cell. An abutting wall surface with an expanded inner diameter is provided at the open end of the side wall of the battery can of the battery cell. The cap covering the open end includes an abutting surface that is pressed into contact with the inner peripheral surface of the abutting wall surface, and an electrode connection portion that is connected to the electrode tab of the electrode assembly housed in the battery can. The pressing depth of the cap with respect to the battery can is regulated by the electrode connection portion 41 of the cap 40 and the electrode tab of the electrode assembly. The abutting surface and the abutting wall surface are joined by welding and electrically connected. One aspect of the present invention provides a method for manufacturing the battery cell, a battery pack including the same, and a vehicle including the same.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0136789 filed on October 21, 2022, and Korean Patent Application No. 10-2023-0026204 filed on February 27, 2023, and all the contents described in the documents of the patent applications are included as part of this specification.

[0002] The present invention relates to a cylindrical battery cell and a manufacturing method thereof, a battery pack including the same, and a vehicle including the same.

Background Art

[0003] A cylindrical battery cell has a structure in which a jelly roll type electrode assembly is accommodated inside a cylindrical metal can, and is more resistant to shock and temperature than a pouch type battery. For this reason, there is an increasing demand to use can type cells as battery cells applied to battery packs for vehicles.

[0004] The process of manufacturing a battery cell applying a cylindrical can includes deep drawing a metal sheet to form a circular bottom and a circular tubular side wall portion connected thereto, accommodating an electrode assembly therein, and then covering and finishing the open end portion of the side wall portion with a cap.

[0005] At this time, as shown in FIG. 1, when the side wall portion 11 of the can and the cap 40 are butt welded, if there is a gap between them, the welding laser (L) may enter the internal space of the can and damage the electrode assembly. Even if welded, the thickness of the welded portion becomes thin and the welding strength is insufficient. Also, if a height difference occurs between the side wall portion of the can and the cap, the possibility of welding defects increases.

[0006] On the other hand, since the battery can is made of metal, it may be even heavier than a pouch type battery. For this reason, research is actively being conducted to increase the volume of individual battery cans and thus increase the electrical capacity of one battery can.

[0007] When the volume of the battery can increases, its diameter also increases accordingly. Different from the prior art, a structure can be applied in which both the positive electrode terminal and the negative electrode terminal are arranged on one side in the axial direction of the battery can, that is, the upper side.

[0008] As described above, the process of manufacturing a battery cell using these cylindrical cans includes a preparation stage of the can in which a metal sheet is deep drawn to form a circular bottom portion 12 and a circular tubular side wall portion 11 connected thereto, and a first electrode terminal is sealed and insulated and fixed at the center of the circular bottom portion of the can, and a stage of preparing a jelly roll type electrode assembly having a first current collector plate and a second current collector plate at both axial ends. Further, it includes an assembly stage in which the electrode assembly is housed in the can, the first current collector plate is connected to the first electrode terminal, the second current collector plate is connected to the can or the cap, the inside of the can is filled with an electrolytic solution, and the open end portion of the side wall portion is covered with a cap for finishing.

[0009] For the cylindrical battery cell manufactured as described above, since a space for accommodating the second current collector plate must be secured inside the can, the volume of the electrode assembly has to be reduced accordingly, resulting in a problem of low energy density. Also, in the process of preparing the electrode assembly, an additional process of connecting the second current collector plate to the second electrode of the electrode assembly is required, increasing the number of process steps. Further, the addition of the second current collector plate as a component and the process of connecting it to the second electrode of the electrode assembly also contribute to an increase in the manufacturing cost of the battery cell.

[0010] On the other hand, since the current collector plate has a certain degree of flexibility, when the current collector plate is welded to the electrode of the electrode assembly and these current collector plates are connected to the electrode terminals of the battery can, there is an advantage that the reliability of the electrical connection is higher compared to a structure in which the electrode of the electrode assembly is directly connected to the electrode terminals of the battery can without a current collector plate.

[0011] Therefore, in order to increase the energy density of the battery cell, it cannot be said that the structure in which the current collector plate is omitted and the electrode of the electrode assembly and the electrode terminal of the battery can are directly connected is an improved structure compared to the structure using the current collector plate.

Summary of the Invention

Problems to be Solved by the Invention

[0012] One aspect of the present invention was devised to solve the above-mentioned problems, and the butting joint portion between the side wall portion of the can and the cap is configured not to restrict the insertion depth of the cap, thereby increasing the adhesion between the cap and the electrode tab of the electrode assembly, and enabling the butting joint process between the side wall portion of the can and the cap not to affect the electrode assembly. The present invention aims to provide a structure of a battery cell.

[0013] Another aspect of the present invention aims to provide a structure of a battery cell in which, during the process of pressing the cap into the open end portion of the can, the butting wall surface around the side wall portion and the butting surface of the cap are not twisted and are strongly butted together.

[0014] Another aspect of the present invention aims to provide a structure of a battery cell that can protect the joint portion between the cap and the battery can.

[0015] Another aspect of the present invention aims to provide a battery cell in which, when connecting the electrode assembly to the electrode terminal of the can, the current collector plate is omitted and the reliability of the electrical connection between the electrode of the electrode assembly and the electrode terminal of the can is ensured.

[0016] Another aspect of the present invention aims to provide a battery cell with fewer parts and fewer manufacturing steps, which is simple and can reduce the manufacturing cost.

[0017] Furthermore, one aspect of the present invention aims to provide a battery cell with a high energy density that is advantageous for mounting on a vehicle, a battery pack including the same, and an automobile.

[0018] The technical problem of the present invention is not limited to the above-mentioned purposes, and other purposes and advantages of the present invention not mentioned can be understood from the following description and can be more clearly understood from the embodiments of the present invention. Also, it is obvious that the purposes and advantages of the present invention can be realized by the means shown in the claims and their combinations.

Means for Solving the Problem

[0019] In order to solve the above-mentioned problems, one aspect of the present invention can be applied to a battery cell in which the electrode assembly 20 is housed inside the battery can 10 and the side wall portion 11 of the battery can 10 and the edge of the cap 40 are joined so that the battery can 10 and the cap 40 are electrically connected.

[0020] The battery can 10 includes a bottom portion 12 and a side wall portion 11 that is connected to the bottom portion 12 and extends in the axial direction.

[0021] The cap 40 covers an open end portion provided at one axial end portion of the side wall portion 11.

[0022] The side wall portion 11 is provided at one axial end portion of the side wall portion 11, extends axially outward, and has a butting wall surface 113 whose inner diameter is larger than the inner peripheral surface of the side wall portion 11.

[0023] The cap 40 has a butting surface 48 that extends in the axial direction such that the outer peripheral surface thereof contacts the inner peripheral surface of the butting wall surface 113.

[0024] The cap 40 includes an electrode connection portion 41 that is electrically connected to the tab of the second electrode 22.

[0025] The insertion depth of the cap 40 into the battery can 10 is defined by the connection portion between the electrode connection portion 41 of the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 housed in the battery can 10.

[0026] The inner peripheral surface of the butting wall surface 113 is joined so as to be electrically connected to the outer peripheral surface of the butting surface 48.

[0027] The connecting portion between the side wall portion 11 with a changing inner diameter and the butting wall surface 113 may not restrict the pushing depth of the cap 40 with respect to the battery can 10. Accordingly, the pushing depth of the cap 40 with respect to the battery can 10 can be determined by the electrode connecting portion 41.

[0028] The axial length (c - f) of the butting surface 48 may be shorter than the axial length (c - e) of the butting wall surface 113. Accordingly, the lower end portion of the butting surface 48 can be prevented from being pushed into the connecting portion between the side wall portion 11 and the butting wall surface 113.

[0029] Moreover, the connecting portion between the side wall portion 11 with a changing inner diameter and the butting wall surface 113 functions to prevent the process of joining the inner peripheral surface of the butting wall surface 113 and the outer peripheral surface of the butting surface 48 from affecting the performance of the electrode assembly 20 housed in the battery can 10.

[0030] The joining can be performed by welding, brazing, or soldering.

[0031] The joining can be performed by seam welding.

[0032] The welding can be performed by a laser irradiated in the axial direction.

[0033] The joining process may include an operation of irradiating a laser to the outer edge in the axial direction of the inner peripheral surface of the butting wall surface 113 and the outer edge in the axial direction of the outer peripheral surface of the butting surface 48 to perform welding.

[0034] At this time, even if there is an unexpected gap between the butting wall surface 113 and the butting surface 48 and the laser irradiated axially for joining enters the inside of the battery can 10, the laser can be shielded by the connecting portion between the side wall portion 11 and the butting wall surface 113. Accordingly, the electrode assembly 20 inside the battery can 10 can be prevented from being exposed to the laser.

[0035] At the connecting portion between the side wall portion 11 and the butting wall surface 113, a constant tapered surface 115 can be provided which is disposed between the inner peripheral surface of the side wall portion 11 and the inner peripheral surface of the butting wall surface 113 and extends radially inward as it goes axially inward, and the inclination thereof is substantially the first inclination (m).

[0036] A curved surface 47 may be connected to the axially inner end portion of the butting surface 48 which extends radially inward as it goes axially inward, and the inclination of the tangent to the outer peripheral surface thereof gradually decreases.

[0037] The position (P) where the inclination of the tangent to the outer peripheral surface of the curved surface 47 corresponds to the first inclination (m) is located radially inward of the tapered surface 115.

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

[0039] Then, even if the curved surface 47 contacts the tapered surface 115 during the process of pushing the cap 40 into the battery can 10 due to a manufacturing error and contacts the boundary portion (g) between the tapered surface 115 and the side wall portion 11, the curved surface 47 may not be deformed due to the steep inclination of the curved surface 47 to prevent the pushing-in of the cap 40.

[0040] The position (P) corresponding to the first inclination (m) where the inclination of the tangent line on the outer peripheral surface of the curved surface 47 may be located on the inner side in the axial direction with respect to the tapered surface 115.

[0041] Then, since the inclination of the surface of the curved surface 47 facing the surface of the tapered surface 115 is even greater, the laser that has entered up to the tapered surface 115 into the unexpected gap between the butting surface 48 and the butting wall surface 113 cannot enter further inside and can disappear between the surface of the tapered surface 115 and the surface of the curved surface 47.

[0042] On the inner side in the radial direction of the curved surface 47 in the cap 40, a receiving surface 45 extending flat in the radial direction can be provided. Since the receiving surface 45 provides an annular flat surface adjacent to the radial edge of the battery can 10, it can be stably seated on the floor so that the battery cell stands stably when standing the battery cell on the floor.

[0043] The outer surface in the axial direction of the receiving surface 45 may be arranged further outside in the axial direction than the outer end portion in the axial direction of the butting surface 48. That is, the height (d) of the outer surface in the axial direction of the receiving surface 45 may be located higher than the height (c) of the outer end portion in the axial direction of the butting surface 48. Thereby, when the battery cell is stood on the floor, the joint portion (M) of the butting surface 48 and the butting wall surface 113 can be protected so as not to directly receive the load.

[0044] Between the curved surface 47 and the receiving surface 45, a first inclined surface 46 that extends outward in the axial direction but has a substantially constant inclination as it goes inward in the radial direction is provided. These curved surface 47 and the first inclined surface 46 can be elastically deformed inward in the radial direction during the pressing process of the cap 40 to increase the adhesion between the butting surface 48 and the butting wall surface 113 and enable these joining processes to be performed smoothly.

[0045] The electrode connection portion 41 of the cap 40 may be arranged on the inner side in the radial direction of the receiving surface 45.

[0046] The electrode connection part 41 may have a shape that is recessed in the axial direction from the receiving surface 45.

[0047] The electrode connection part 41 can be provided by plastic working such that a predetermined part of the metal sheet-like cap 40 is recessed inward in the axial direction.

[0048] A second inclined surface 49 that extends inward in the axial direction but has a substantially constant inclination can be provided between the electrode connection part 41 and the receiving surface 45 in the radial direction, such that the inclination increases as it goes inward in the radial direction.

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

[0050] Preferably, the electrode connection part 41 may extend more than 0.7 times the radius of the battery can 10 outward in the radial direction.

[0051] The electrode connection part 41 can provide a bottom surface that extends flat in the radial direction.

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

[0053] Then, the lower end part of the curved surface 47 can be axially separated from the electrode assembly 20 housed inside the battery can 10, and the bottom surface of the electrode connection part 41 can be made to adhere closely to the tab of the second electrode 22 of the electrode assembly 20. Thereby, the joining process between the electrode connection part 41 and the tab of the second electrode 22 can be made to proceed smoothly.

[0054] In one example, the cap 40 may not be provided with a liquid injection port 42.

[0055] In another example, the cap 40 may be provided with a liquid injection port 42.

[0056] The liquid injection port 42 may be provided at the center of the electrode connection portion 41.

[0057] The liquid injection port 42 may be provided at a protruding portion 43 that protrudes further outward in the axial direction than the electrode connection portion 41 around the liquid injection port 42.

[0058] A plurality of the electrode connection portions 41 may be provided, and the plurality of electrode connection portions 41 may each be recessed inside the battery can 10 and extend in the radial direction.

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

[0060] The electrode connection portions 41 may be arranged at equal intervals in the circumferential direction.

[0061] A pair of electrode connection portions 41 facing each other with respect to the center of the cap 40 may be aligned in a row.

[0062] Four electrode connection portions 41 may be provided at intervals of 90 degrees.

[0063] An outer surface 44 that protrudes further outward in the axial direction than the electrode connection portion 41 may be provided between two adjacent electrode connection portions 41 in the circumferential direction.

[0064] The outer surface 44 may be connected to the inside in the radial direction of the receiving surface 45.

[0065] The protruding height of the outer surface 44 may correspond to or be lower than the protruding height of the receiving surface 45.

[0066] When the protruding height of the outer surface 44 corresponds to the protruding height of the receiving surface 45, the outer surface 44 also contacts the floor when the battery cell is standing on the floor, so that the radial dimension of the receiving surface 45 can be minimized. Thereby, the radial length of the electrode connection portion 41 can be further ensured.

[0067] The outer surface 44 may protrude further axially than the protrusion 43.

[0068] The protrusion 43 can be connected to the inside in the radial direction of the outer surface 44.

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

[0070] The vent 60 can be provided outside in the radial direction than the electrode connection portion 41.

[0071] The vent 60 can be provided at substantially the center of the receiving surface 45 in the radial direction.

[0072] The vent 60 can be defined by a thin-walled portion provided on the cap 40.

[0073] The vent 60 can be defined by a plug 50 covering the liquid injection port 42.

[0074] The vent 60 can be defined by a joint portion between the cap 40 and the battery can 10.

[0075] A first electrode terminal 13 can be attached to the center of the bottom 12 of the battery can 10.

[0076] The first electrode terminal 13 can be attached to the bottom 12 in a state insulated from the bottom 12.

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

[0078] The electrode assembly 20 is in a form in which the first electrode 21 and the second electrode 22 are wound in a jelly roll shape.

[0079] The electrode assembly 20 is accommodated inside the battery can 10 in a state of being axially aligned with the battery can 10.

[0080] The liquid injection port 42 and the hollow portion of the winding core of the electrode assembly 20 may be axially aligned.

[0081] The tab of the first electrode 21 may be located at one end portion in the axial direction of the electrode assembly 20.

[0082] The tab may be a portion where the metal foil 23 of the first electrode 21 extends to one end portion in the axial direction of the electrode assembly 20.

[0083] The tab portions of the first electrode 21 are bent in the radial direction and overlap each other, thereby providing 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] Thereby, the first electrode terminal 13 can have a first polarity.

[0087] The tab of the second electrode 22 may be located at the other end portion in the axial direction of the electrode assembly 20.

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

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

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

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

[0092] A current collector plate 35 is joined to the tab of the second electrode 22 and electrically connected thereto. The electrode connection portion 41 may be joined to the current collector plate 35 and electrically connected to the tab of the second electrode 22.

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

[0094] In addition to this, the electrode connection portion 41 may be directly joined to the tab of the second electrode 22 and electrically connected thereto.

[0095] The joining portion of the electrode connection portion 41 and the tab of the second electrode 22 may extend in the radial direction.

[0096] The electrode connection portion 41 and the tab of the second electrode 22 may be joined and fixed to each other and electrically connected by a welded portion (W) formed by a laser irradiated on the surface of the electrode connection portion 41 along the radial direction.

[0097] The electrode connection portion 41 and the tab of the second electrode 22 may be connected and fixed by other methods in addition to the welding method. This may include, for example, brazing or soldering methods.

[0098] The connection between the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 can be performed in a state where the electrode assembly 20 is housed in the battery can 10 and the cap 40 is pushed into the battery can 10.

[0099] It is preferable that the connection between the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 is made before the joining of the cap 40 and the battery can 10. However, of course, differently, the connection between the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 may be made after the joining of the cap 40 and the battery can 10.

[0100] The cap 40 may be pressed into the battery can 10 after injecting an electrolytic solution into the battery can 10.

[0101] The cap 40 may be pressed into the battery can 10 before injecting an electrolytic solution into the battery can 10. Thereby, the connection between the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 and the fixing of the cap 40 to the battery can 10 can be performed before injecting an electrolytic solution into the battery can 10.

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

[0103] Also, one aspect of the present invention provides a method for manufacturing a battery cell to which the cap is applied.

[0104] The first embodiment of the manufacturing method includes a preparation stage of a battery can, a preparation stage of an electrode assembly, a preparation stage of a cap, an accommodation stage of the electrode assembly, a connection stage of a first electrode terminal, an injection stage, a pressing stage of the cap, and a fixing stage of the cap.

[0105] The preparation stage of the battery can includes preparing a battery can 10 having a side wall portion 11, a bottom portion 12 connected to one axial end portion of the side wall portion 11, and an open end portion provided at the other axial end portion of the side wall portion 11, forming a butting wall surface 113 with an expanded inner diameter at the other end portion of the side wall portion 11, and hermetically fixing and insulating a first electrode terminal 13 at the center of the bottom portion 12.

[0106] The preparation step of the electrode assembly includes a process of manufacturing an electrode assembly 20 including a first electrode 21 and a second electrode 22, with the tabs of the first electrode 21 and the second electrode 22 arranged on both axial sides respectively.

[0107] The preparation step of the cap includes a process of manufacturing a cap 40 including a butt joint surface 48 extending in the axial direction and an electrode connection part 41 electrically connected to the tab of the second electrode 22, such that the outer peripheral surface contacts the inner peripheral surface of the butt joint wall surface 113.

[0108] The accommodation step of the electrode assembly includes a process of accommodating the electrode assembly 20 in the battery can 10 after the preparation step of the battery can and the preparation step of the electrode assembly, such that the tab of the first electrode 21 faces the bottom 12 of the battery can 10.

[0109] The connection step of the first electrode terminal includes a process of connecting the tab of the first electrode 21 and the first electrode terminal 13 after the accommodation step of the electrode assembly.

[0110] The liquid injection step includes a process of injecting electrolyte into the battery can 10 after the connection step of the first electrode terminal.

[0111] The pressing-in step of the cap includes a process of pressing the cap 40 into the open end of the battery can 10 after the preparation step of the cap and the liquid injection step, and bringing the electrode connection part 41 into close contact with the tab of the second electrode 22.

[0112] The fixing step of the cap includes a process of joining and electrically connecting the electrode connection part 41 to the tab of the second electrode 22, and joining and electrically connecting the outer peripheral surface of the butt joint surface 48 to the inner peripheral surface of the butt joint wall surface 113 after the pressing-in step of the cap.

[0113] The first embodiment of the manufacturing method can be applied to the manufacturing of a battery cell using a cap without an injection port.

[0114] The second embodiment of the manufacturing method includes a battery can preparation stage, an electrode assembly preparation stage, a cap preparation stage, an electrode assembly accommodation stage, a first electrode terminal connection stage, a cap pressing-in stage, a cap fixing stage, and a liquid injection stage.

[0115] The battery can preparation stage includes preparing a battery can 10 having a side wall portion 11, a bottom portion 12 connected to one axial end of the side wall portion 11, and an open end provided at the other axial end of the side wall portion 11, forming a butting wall surface 113 with an expanded inner diameter at the other end of the side wall portion 11, and sealing and insulatingly fixing a first electrode terminal 13 at the center of the bottom portion 12.

[0116] The electrode assembly preparation stage includes manufacturing an electrode assembly 20 having a first electrode 21 and a second electrode 22, and arranging the tabs of the first electrode 21 and the tabs of the second electrode 22 on both axial sides respectively.

[0117] The cap preparation stage includes manufacturing a cap 40 having a butting surface 48 extending in the axial direction such that the outer peripheral surface contacts the inner peripheral surface of the butting wall surface 113, an electrode connection portion 41 electrically connected to the tab of the second electrode 22, and a liquid injection port 42 provided at the central portion of the electrode connection portion 41.

[0118] The electrode assembly accommodation stage includes, after the battery can preparation stage and the electrode assembly preparation stage, accommodating the electrode assembly 20 in the battery can 10 such that the tab of the first electrode 21 faces the bottom portion 12 of the battery can 10.

[0119] The first electrode terminal connection stage includes, after the electrode assembly accommodation stage, connecting the tab of the first electrode 21 and the first electrode terminal 13.

[0120] The cap pressing-in stage includes pressing the cap 40 into the open end of the battery can 10 to bring the electrode connection portion 41 into close contact with the tab of the second electrode 22.

[0121] The fixing step of the cap includes, after the pushing-in step of the cap, joining the electrode connection part 41 to the tab of the second electrode 22 to electrically connect them, and joining the outer peripheral surface of the butting surface 48 to the inner peripheral surface of the butting wall surface 113 to electrically connect them.

[0122] The electrolyte injection step includes, after the connection step of the first electrode terminal and the fixing step of the cap, injecting an electrolyte into the battery can 10 through the electrolyte injection port 42, and sealing and finishing the electrolyte injection port 42.

[0123] The third embodiment of the manufacturing method includes a preparation step of a battery can, a preparation step of an electrode assembly, a preparation step of a cap, a connection step of a second electrode, a step of housing the electrode assembly and pushing in the cap, a step of connecting the first electrode terminal and fixing the cap, and an electrolyte injection step.

[0124] The preparation step of the battery can includes preparing a battery can 10 having a side wall portion 11, a bottom portion 12 connected to one axial end of the side wall portion 11, and an open end provided at the other axial end of the side wall portion 11, forming a butting wall surface 113 with an expanded inner diameter at the other end of the side wall portion 11, and sealing and insulatingly fixing a first electrode terminal 13 at the center of the bottom portion 12.

[0125] The preparation step of the electrode assembly includes manufacturing an electrode assembly 20 including a first electrode 21 and a second electrode 22, and arranging the tabs of the first electrode 21 and the second electrode 22 on both axial sides.

[0126] The preparation step of the cap includes manufacturing a cap 40 having a butting surface 48 extending in the axial direction such that the outer peripheral surface contacts the inner peripheral surface of the butting wall surface 113, an electrode connection part 41 electrically connected to the tab of the second electrode 22, and an electrolyte injection port 42 provided at the central part of the electrode connection part 41.

[0127] The connecting step of the second electrode includes a step of joining and electrically connecting the electrode connection portion 41 of the cap 40 to the tab of the second electrode 22 after the preparation step of the electrode assembly and the preparation step of the cap.

[0128] The step of accommodating the electrode assembly and pressing the cap includes a step of accommodating the electrode assembly 20 in the battery can 10 so that the tab of the first electrode 21 faces the bottom 12 of the battery can 10 and pressing the cap 40 into the open end of the battery can 10 after the preparation step of the battery can and the second electrode connecting step.

[0129] The step of connecting the first electrode terminal and fixing the cap includes a step of connecting the tab of the first electrode 21 and the first electrode terminal 13 and joining and electrically connecting the outer peripheral surface of the butting surface 48 to the inner peripheral surface of the butting wall surface 113 after the step of accommodating the electrode assembly and pressing the cap.

[0130] The above-mentioned liquid injection step includes a step of injecting electrolyte into the battery can 10 through the liquid injection port 42 and sealing and finishing the liquid injection port 42 after the connecting step of the first electrode terminal and the fixing step of the cap.

[0131] The second embodiment and the third embodiment of the above manufacturing method can be applied to the manufacture of a battery cell to which a cap provided with a liquid injection port is applied.

[0132] One aspect of the present invention provides a high energy density battery pack including the above-mentioned battery cell.

[0133] One aspect of the present invention provides an automobile equipped with a high energy density battery pack, which reduces the volume and load occupied by the battery pack.

Effect of the Invention

[0134] According to one aspect of the present invention, by providing a difference in the inner diameters between the side wall portion and the butting wall surface and joining the inner peripheral surface of the can and the outer peripheral surface of the cap, it is possible to prevent the phenomenon that the joining process affects the electrode assembly inside the battery can.

[0135] Also, according to one aspect of the present invention, since the can 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. This enables the cap to also function as a current collector plate.

[0136] Also, according to one aspect of the present invention, since the point of the curved surface having a tangent corresponding to the inclination of the tapered surface exists radially inside the tapered surface, the side wall portion does not regulate the pressing depth of the cap, and the joining process of the can and the electrode of the electrode assembly can be smoothly performed.

[0137] Also, according to one aspect of the present invention, since the point of the curved surface having a tangent corresponding to the inclination of the tapered surface exists axially inside the tapered surface, even if there is a gap between the side wall portion and the can, it is possible to prevent the phenomenon that the joining process of the can and the cap affects the electrode assembly.

[0138] Also, according to one aspect of the present invention, since the curved surface and the first inclined surface are interposed in a goose neck shape between the butting surface and the receiving surface of the cap, in the process of pressing the cap into the open end of the can, the butting wall surface around the side wall portion and the butting surface of the cap are not twisted, and they can be strongly butted.

[0139] Also, according to one aspect of the present invention, since the receiving surface is arranged axially further outside than the welding portion, even if the cylindrical battery cell is arranged in a form where the cap is placed on the floor, the welding portion can be protected.

[0140] According to one aspect of 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 portion of the can, the current collector plate can be omitted, the energy density of the battery cell can be increased, the number of parts of the battery cell can be reduced, and the manufacturing process can be simplified. Thereby, the manufacturing cost per unit of the battery cell can be reduced.

[0141] According to one aspect of the present invention, since the electrode connection portion of the cap connected to the tab of the second electrode extends along the radial direction, the cap is electrically directly connected from the core portion to the outer peripheral portion of the second electrode, and the internal resistance can be greatly reduced.

[0142] According to one aspect of the present invention, the cap is provided with a plurality of electrode connection portions extending in the radial direction, and each electrode connection portion is recessed inward in the axial direction and protrudes toward the tab of the second electrode. Therefore, the adhesion between each electrode connection portion and the tab of the second electrode can be ensured, and thereby the joining quality between them can be ensured.

[0143] In addition, these shapes can greatly improve the torsional resistance of the cap, and thus the adhesion can be enhanced as a whole along the circumferential direction at the fixed portion where the cap and the battery can are provided. Therefore, the joining quality between the battery can and the cap can also be greatly improved.

[0144] According to one aspect of the present invention, the electrode connection portions of the cap are radially arranged, arranged at equal intervals in the circumferential direction, and the torsional resistance can be ensured uniformly along the circumferential direction, and the current path can be uniformly distributed.

[0145] According to one aspect of the present invention, a pair of electrode connection portions facing each other with respect to the center of the cap are aligned in a row, and the shape of the jig can be simply implemented to press the cap into the battery can or to bring it into close contact with the electrode assembly, and the locus of the welding line can be simplified.

[0146] According to one aspect of the present invention, four electrode connection portions are arranged at 90-degree intervals to ensure the torsional resistance of the cap and simplify the welding process. At the same time, the adhesion of each of the plurality of electrode connection portions to the tab of the second electrode can be ensured, the plastic working portion of the cap can be suppressed, and the decrease in the rigidity of the cap due to plastic working can be suppressed.

[0147] According to one aspect of the present invention, an outer surface that is axially located further outside than the electrode connection part is disposed between two circumferentially adjacent electrode connection parts in the cap, so that the joint part between the cap and the electrodes of the electrode assembly can be protected.

[0148] According to one aspect of the present invention, when the battery can is placed correctly, that is, when the receiving surface and the outer surface are placed on the floor, the receiving surface and the outer surface can support the load of the battery cell. As a result, the outer surfaces located on both sides in the circumferential direction of the electrode connection part exert an effect of pressing the electrode connection part toward the tab of the second electrode, minimizing the phenomenon that the joint part between the cap and the tab of the second electrode is damaged due to vibration or impact.

[0149] The liquid injection port provided at the central part of the cap protrudes from the electrode connection part, so that the phenomenon that the welding heat or bonding heat generated when covering the liquid injection port with a plug is transmitted to the electrode assembly can be minimized.

[0150] When the vent provided in the cap is provided radially outside the electrode connection part or the welding part, a wider area of the cap where the pressure resistance of the battery can acts can be ensured, the vent action can occur more easily, and when the vent part is damaged by the vent, the electrical connection between the second electrode and the battery can can be interrupted.

[0151] According to one aspect of the present invention, since the vent is provided at the radial center of the receiving surface, the load applied to the receiving surface is not transmitted to the vent by the weight of the battery cell or the structure connected to the battery cell, and is respectively supported by the can and the electrode assembly via the first inclined surface and the electrode connection part, so that damage to the vent caused by an unexpected external force can be prevented.

[0152] The above-described effects and the specific effects of the present invention will be described and described while explaining the embodiments for carrying out the following invention.

Brief Description of the Drawings

[0153]

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Figure 15

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Figure 36

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Figure 38

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Embodiments for Carrying Out the Invention

[0154] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings. Thus, those having ordinary knowledge in the technical field to which the present invention pertains can easily implement the technical idea of the present invention. In the description of the present invention, when it is determined that a specific description of a known technique related to the present invention obscures the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0155] Although terms such as "first", "second", etc. are used to describe various components, these components are of course not limited by these terms. These terms are merely used to distinguish one component from another, and of course, unless otherwise stated, the first component may be the second component.

[0156] Unless otherwise stated throughout the specification, each component may be in the singular or plural.

[0157] Hereinafter, when it is said that any configuration is arranged "above (or below)" a component or "on (or under)" a component, it means that not only is any configuration arranged in contact with the upper surface (or lower surface) of the above-mentioned component, but other configurations may also be interposed between the above-mentioned component and any configuration arranged above (or below) the above-mentioned component.

[0158] Also, when it is described that a certain component is "connected", "coupled", or "joined" to another component, it should be understood that although the above-mentioned components may be directly connected or joined to each other, other components may "intervene" between the components, or each component may be "connected", "coupled", or "joined" through other components.

[0159] The singular expressions used in this specification include plural expressions unless otherwise clearly indicated in the context. Terms such as "configured" or "comprising" in this application should not be construed as necessarily including all of the multiple components or multiple steps described in the specification. Some of these components or steps may not be included, or may include additional components or steps.

[0160] Throughout the specification, when it is "A and / or B", this means A, B, or A and B unless otherwise stated, and when it is "C to D", this means C or more and D or less unless otherwise stated.

[0161] In the description of the embodiments, the axial direction refers to the direction in which the axis forming the winding center of the jelly roll type electrode assembly extends, the radial direction refers to the direction of approaching (centripetal) or moving away (centrifugal) from the axis, and the circumferential direction refers to the direction surrounding the axis.

[0162] The width direction in the unfolded state of the electrode assembly corresponds to the axial direction of the jelly roll. The length direction in the unfolded state of the electrode assembly corresponds to the circumferential direction of the jelly roll.

[0163] Hereinafter, with reference to FIGS. 2 to 13, the structure of the cylindrical battery cell according to the embodiment of the present invention will be described.

[0164] The battery cell of the embodiment may be, for example, a cylindrical battery cell in which the form factor ratio (the value obtained by dividing the diameter of the cylindrical battery cell by the height, that is, the ratio of the diameter (Φ) to the height (H)) is greater than approximately 0.4.

[0165] Here, the form factor means a value indicating the diameter and height of the cylindrical battery cell. The cylindrical battery cell applied to the pressure tester may be, for example, 46110 cell, 48750 cell, 48110 cell, 48800 cell, 46800 cell. In the numerical value indicating the form factor, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the last digit of 0 indicates that the cross section of the cell is circular.

[0166] The battery cell applied to the pressure tester may be a substantially cylindrical cell having a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0167] The battery cell according to another embodiment may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0168] Battery cells according to still other embodiments may be cylindrical battery cells that are substantially cylindrical, having a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0169] Battery cells according to still other embodiments may be cylindrical battery cells that are substantially cylindrical, having a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0170] Battery cells according to still other embodiments may be cylindrical battery cells that are substantially cylindrical, having a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0171] The pressure tester according to one aspect of the present invention can of course be applied to battery cells having a form factor ratio of approximately 0.4 or less, such as 18650 cells, 21700 cells, etc. In the case of 18650 cells, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. In the case of 21700 cells, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0172] Referring to FIGS. 2 and 10, the battery can 10 includes a cylindrical side wall portion 11 and a bottom portion 12 connected to one axial end of the side wall portion 11.

[0173] The bottom portion 12 and the side wall portion 11 can be manufactured by deep drawing a metal sheet with nickel plated on the surface of steel in a deep drawing process, and trimming with a punch while gripping the tip of the side wall portion 11 with a blank holder. Of course, the material of the can 10 is not limited to this.

[0174] A hole may be formed in the central portion of the bottom 12, and the first electrode terminal 13 may be inserted and coupled to the hole. The first electrode terminal 13 can be fixed to the bottom 12 by riveting with the terminal gasket 14 interposed therebetween. The terminal gasket 14 is interposed between the first electrode terminal 13 and the bottom 12 to seal the inside and outside of the battery can 10, prevent leakage of the electrolytic solution, and electrically insulate the first electrode terminal 13 and the bottom 12.

[0175] However, the connection method between the first electrode terminal 13 and the bottom 12 is not limited thereto. For example, any structure that can seal between the first electrode terminal 13 and the bottom 12 and electrically insulate the first electrode terminal 13 and the bottom 12 can adopt various other fixing methods, such as bolt-nut connection method, glass seal method, or chromium coating & PP-MAH thermal bonding method, etc.

[0176] The first electrode terminal 13 has a first polarity, and the battery can 10 has a second polarity. Accordingly, both the bottom 12 of the battery can 10 and the side wall portion 11 connected thereto can have the second polarity.

[0177] Accordingly, both the first electrode terminal 13 and the second electrode terminal 15 may be disposed at one end in the axial direction of the battery can 10. Then, both the bus bar connected to the first electrode terminal 13 and the bus bar connected to the second electrode terminal 15 may be located at one end in the axial direction of the battery can 10, that is, at the upper part.

[0178] In one example, the first electrode terminal 13 may be a positive electrode terminal, and the second electrode terminal 15 may be a negative electrode terminal. Of course, the reverse may also be true.

[0179] The electrode assembly 20 is accommodated in the battery can 10. As shown in FIG. 3, the electrode assembly 20 has a predetermined width and includes a first electrode 21, a second electrode 22, and a separator 28 extending in the length direction. As shown in FIGS. 4 and 5, after forming a laminate in which the first electrode 21, the separator 28, the second electrode 22, and the separator 28 are laminated in this order, it is manufactured in a jelly roll shape wound around a winding core shaft.

[0180] The first electrode 21 may be a positive electrode, and the second electrode 22 may be a negative electrode. Of course, the reverse may also be true.

[0181] The first electrode 21 and the second electrode 22 are manufactured in a sheet shape. The electrode sheet is manufactured in a form in which an active material layer 24 is applied to the surface of a metal foil 23. The electrode sheet includes a grounded portion 25 region where the active material layer 24 is applied and an ungrounded portion 26 region where the active material layer 24 is not applied. The positive electrode sheet is provided with an ungrounded portion 26 region on one side in the width direction, and the negative electrode sheet is provided with an ungrounded portion 26 region on the other side in the width direction.

[0182] The ungrounded portion 26 region is exposed or protrudes in the width direction in the laminate. The ungrounded portion 26 itself functions as an electrode tab.

[0183] Notches can be formed in the ungrounded portion 26 at a predetermined interval to form flag-shaped notch tabs 27.

[0184] In the embodiment, it is exemplified that the notch tab 27 is in the shape of an isosceles trapezoid. However, these forms may be in various forms such as a semi-circle, an anti-elliptical shape, a triangle, a rectangle, a parallelogram, etc.

[0185] Also, in the embodiment, it is exemplified that the notch tabs 27 arranged along the length direction have the same width. However, the width of the notch tab may be in a form that gradually or stepwise widens from the winding core side to the outer peripheral side.

[0186] In addition, in the embodiment, an example is illustrated in which the height of the notch tab 27 gradually increases from the core side to the outer peripheral side. However, the height of these notch tabs can also be made constant or gradually decrease.

[0187] In addition, in the embodiment, an example is illustrated in which the structure where the notch tab 27 is deleted is provided in a predetermined section of the centripetal side end of the plain portion 26 and a predetermined section of the centrifugal side end. However, it is needless to say that the notch tab at the centripetal side end of the plain portion may not be deleted, and the notch tab at the centrifugal side end of the plain portion may not be deleted either.

[0188] In the jelly roll type electrode assembly 20, the notch tab 27 can be bent in the radial direction to be flattened. The notch tab 27 may be bent inward or outward in the radial direction. In the embodiment, as shown in FIGS. 6 and 7, an example is illustrated in which the notch tab 27 is bent inward in the radial direction.

[0189] The notch tab 27 can be bent one by one in the process of winding the laminate to form the jelly roll type electrode assembly 20. In contrast, the notch tab 27 can also be bent all at once after winding the laminate to form the jelly roll type electrode assembly.

[0190] In this way, the notch tabs 27 of the first electrode 21 and the notch tabs 27 of the second electrode 22 that are overlapped while being bent in the radial direction can provide planes that are substantially perpendicular to the axial direction at both axial ends of the electrode assembly 20 as shown in FIG. 7, respectively.

[0191] A current collector plate 31 may be joined to the substantially flat surface provided by bending the notch tabs 27 exposed at both axial ends of the electrode assembly 20 as shown in FIG. 8.

[0192] The current collector plate 31 can be manufactured by punching, trimming, piercing, and bending a metal sheet.

[0193] Referring to FIG. 8, the current collector plate 31 includes a terminal connection portion 32 extending radially from the central portion, a ring portion 33 connecting the centrifugal side edges of the terminal connection portion 32 in the circumferential direction, and an electrode connection portion 34 extending from the ring portion 33 toward the centripetal side but not connected to the terminal connection portion 32. The central portion of the terminal connection portion 32 covers at least a part of the core hollow portion of the electrode assembly 20.

[0194] The electrode connection portion 34 is joined to the notch tab 27 of the first electrode 21 of the electrode assembly 20 by a method such as laser welding before the electrode assembly 20 is placed in the battery can 10.

[0195] Referring to FIG. 9, a current collector plate may not be connected to the notch tab 27 of the second electrode 22 of the electrode assembly 20. Of course, the present invention is not limited to a structure in which the current collector plate is not connected to the notch tab 27 of the second electrode 22.

[0196] As shown in FIGS. 10 and 11, the electrode assembly 20 is accommodated in the battery can 10 in a state where the current collector plates 31 are aligned so as to face the bottom 12 of the battery can 10. At this time, an insulator 19 is interposed between the current collector plate 31 and the bottom 12 of the battery can 10 to electrically insulate the current collector plate 31 and the bottom 12.

[0197] And the terminal connection portion 32 of the current collector plate 31 is joined to the first electrode terminal 13 fixed to the battery can 10 by a method such as resistance welding, ultrasonic welding, or laser welding. The welding device for forming the welded portion (W) between the current collector plate 31 and the first electrode terminal 13 passes through the core hollow portion of the electrode assembly 20 from the other end in the axial direction of the electrode assembly 20 and approaches the back surface of the center of the terminal connection portion 32 of the current collector plate 31 to perform welding. Of course, it goes without saying that the current collector plate 31 and the first electrode terminal 13 can also be joined by other methods such as brazing or soldering. That is, as long as the current collector plate 31 and the first electrode terminal 13 are connected electrically and fixed to each other, various methods can be applied.

[0198] Referring to FIGS. 12 and 13, in a state where the electrode assembly 20 is housed in the battery can 10 and the first electrode 21 is connected to the first electrode terminal 13, the notch tab 27 of the second electrode 22 may be directly connected to the cap 40 that is pushed in through the open end of the battery can 10. Thereby, the second electrode 22 is electrically connected via the welded portion (W) of the notch tab 27 and the cap 40. Of course, it goes without saying that other joining methods such as brazing and soldering can also be applied to the notch tab 27 and the cap 40 in addition to the welding method.

[0199] The edge of the cap 40 is joined to the side wall portion 11 of the battery can 10, electrically connected, and sealed and fixed. Thereby, the second electrode 22 may be electrically connected to the cap 40 and the battery can 10. For the processing of the joint portion (M) between the cap 40 and the battery can 10, various methods that can be electrically connected and joined by sealing, such as welding, brazing, and soldering, can be applied.

[0200] The cap 40 shown in FIGS. 10 to 14 and its assembly process are illustrated as an example, and hereinafter, various embodiments of the structure of the cap 40 and the assembly method thereby will be described. In the embodiments described later, although it is exemplified that these joint portions are joined by welding, it is natural that the present invention is not limited thereto.

[0201] [First Embodiment] Hereinafter, with reference to FIGS. 14 to 21, a first embodiment of the cap and the structure of the battery cell to which this is applied will be described.

[0202] The cap 40 can be manufactured by press-forming a circular metal sheet.

[0203] The cap 40 has a substantially disc shape so as to be able to close the open end of the battery can 10. The cap 40 of the first embodiment includes a butting surface 48, a curved surface 47, a first inclined surface 46, a receiving surface 45, a second inclined surface 49, and an electrode connection portion 41 in this order from the outer side in the radial direction to the inner side.

[0204] The butting surface 48 is provided at the outer end in the radial direction of the cap 40 and extends in the axial direction so that its outer peripheral surface contacts the inner periphery of the side wall portion of the battery can 10. The butting surface 48 extends from the outer side in the axial direction to the inner side in the axial direction. The outer peripheral surface of the butting surface 48 can have a cylindrical surface.

[0205] The curved surface 47 is connected to the lower end portion of the butting surface 48 of the cap 40, that is, the inner end portion in the axial direction of the butting surface 48, and has a downwardly convex cross section that extends radially inward as it goes inward in the axial direction. The curved surface 47 gradually becomes less inclined as it moves away from the butting surface 48. Since the butting surfaces 48 extend side by side in the axial direction, the curved surface 47 can gradually reduce the inclination of the tangent of its outer peripheral surface from 90 degrees as it moves away from the butting surface 48.

[0206] The curved surface 47 may extend to a point where the inclination of the tangent becomes 0 degrees. The point where the inclination of the tangent in the curved surface 47 becomes 0 degrees may be the portion that extends to the innermost side in the axial direction in the curved surface 47. More preferably, the curved surface 47 may further extend beyond 0 degrees to an angle corresponding to the inclination of the first inclined surface 46 with respect to the inclination of the tangent.

[0207] The first inclined surface 46 is provided between the curved surface 47 and the receiving surface 45. The first inclined surface 46 extends outward in the axial direction as it goes inward in the radial direction, and its inclination may be substantially the second inclination and may be constant. The second inclination in the embodiment is exemplified to be around 30 degrees. Then, the angle between the first inclined surface 46 and the butting surface 48 can be around 60 degrees.

[0208] On the inner side in the radial direction of the curved surface 47 in the cap 40, a receiving surface 45 extending horizontally in the radial direction is provided. The receiving surface 45 may be connected to the inner end in the radial direction of the first inclined surface 46 and may extend horizontally inward in the radial direction from the connection portion.

[0209] Since the surface of the receiving surface 45 has a flat ring shape, when the battery cell is stood up so that the cap 40 is placed on the floor as shown in FIG. 2, it serves as the legs of the battery cell.

[0210] Referring to FIG. 20, the outer surface (d) in the axial direction of the receiving surface 45 is arranged further outward in the axial direction than the outer end (c) in the axial direction of the butting surface 48. Therefore, as shown in FIG. 2, even when the battery cell is stood up, the cap 40 is in contact with the floor, and the battery cell is placed, it is possible to prevent the welding portion between the cap 40 and the can 10 from directly contacting the floor and protect the welding portion.

[0211] On the inner side in the radial direction of the receiving surface 45 in the cap 40, an electrode connection portion 41 extending horizontally in the radial direction is provided. Referring to FIG. 20, the inner surface (a) in the axial direction of the electrode connection portion 41, that is, the bottom surface, is arranged further inward in the axial direction than the inner end (b) in the axial direction of the curved surface 47, that is, the point where the inclination is 0.

[0212] Thus, when the cap 40 is pressed into the battery can 10, the cap 40 can be pressed until the bottom surface (the inner surface in the axial direction) of the electrode connection portion 41 is in close contact with the tab of the second electrode 22 of the electrode assembly 20 housed inside the can 10. That is, according to the embodiment, the pressing depth of the cap 40 with respect to the battery can 10 can be restricted by the interference or contact between the electrode connection portion 41 and the tab of the second electrode 22 of the electrode assembly 20 housed in the battery can 10.

[0213] The electrode connection portion 41 can be in close contact with the tab of the second electrode 22 of the electrode assembly 20, and they can be joined to each other. These joints can be made by welding. The weld portion (W) between the electrode connection portion 41 and the tab 27 of the second electrode 22 can be formed by a laser that irradiates the outer surface in the axial direction of the electrode connection portion 41 on the outside in the axial direction. The laser can be irradiated in a scanning manner along the radial direction to form a weld portion (W) that extends long in the radial direction.

[0214] In this way, the cap 40 serves as a lid that finishes the open end of the battery can 10 and also serves as a current collector plate for the second electrode 22. Therefore, the cap 40 has a second polarity, and the side wall portion 11 welded to this and the bottom portion 12 connected thereto can also have the second polarity.

[0215] The electrode connection portion 41 may extend radially outward by more than half of the radius of the battery can 10. Preferably, the electrode connection portion 41 may extend by 0.7 times or more the radius of the battery can 10. The electrode connection portion 41 may extend flat in the radial direction.

[0216] Since the electrode connection portion 41 of the cap 40 of the first embodiment has a flat ring shape with a sufficient radial length, a sufficient welding area with the tab of the second electrode 22 can be ensured.

[0217] The first embodiment illustrates a structure in which the tab of the second electrode 22 is welded to the electrode connection portion 41 of the cap 40 without a separate current collector plate, and is electrically connected. However, the present invention does not exclude the use of a current collector plate. That is, it goes without saying that a current collector plate may be welded to the tab of the second electrode 22, and the electrode connection portion 41 of the cap 40 may be welded to the current collector plate. That is, an assembly structure in which a flat current collector plate is interposed between the bottom surface of the electrode connection portion 41 and the tab of the second electrode 22 is also applicable.

[0218] Between the receiving surface 45 and the electrode connection portion 41, there is provided a second inclined surface 49 that extends inward in the axial direction as it goes inward in the radial direction, and the inclination thereof is substantially a third inclination and is constant. The third inclination in the embodiment is exemplified to be about 75 degrees. The second inclination of the first inclined surface 46 may be smaller than the third inclination of the second inclined surface 49. That is, the second inclined surface 49 may be steeper than the first inclined surface 46. Thereby, the radial lengths of the receiving surface 45 and the electrode connection portion 41 can be ensured to the maximum extent.

[0219] On the other hand, at the open end of the side wall portion 11 of the battery can 10, a butting wall surface 113 whose inner diameter is expanded more than the inner peripheral surface of the side wall portion 11 is provided.

[0220] A press-in guide surface 111 for guiding the insertion of the cap 40 can be provided at the corner of the outer end in the axial direction of the inner peripheral surface of the butting wall surface 113. Although the press-in guide surface 111 is exemplified to be in a round processed pellet shape, it goes without saying that it may be in a chamfered shape like a chamfer.

[0221] The butting wall surface 113 can be formed by pressing the edge of the inner peripheral surface of the side wall portion 11.

[0222] The inner peripheral surface of the butting wall surface 113 can have a cylindrical surface.

[0223] The outer diameter of the mating surface 48 and the inner diameter of the mating wall surface 113 can correspond. In order to ensure the adhesion force between the two surfaces, the outer diameter of the mating surface 48 may be slightly larger than the inner diameter of the mating wall surface 113. Thereby, when the cap 40 is pressed into the open end of the battery can 10, the mating wall surface 113 and the mating surface 48 may be strongly adhered in the radial direction.

[0224] The curved surface 47, the first inclined surface 46, and the second inclined surface 49 connected to the inner side in the radial direction of the mating surface 48 of the cap 40 provide a cross-sectional shape in which the cap 40 can be elastically deformed inward in the radial direction.

[0225] Specifically, when the mating surface 48 of the cap 40 receives a force inward in the radial direction, as shown in FIG. 18, elastic deformation of the curved surface 47 is induced, and the connection portion between the first inclined surface 46 and the receiving surface 45, the receiving surface 45 and the second inclined surface 49, and the connection portion between the second inclined surface 49 and the electrode connection portion 41 are uniformly elastically deformed.

[0226] Thereby, the shape in which the mating surfaces 48 extend in the axial direction and the shape in which the receiving surface 45 and the electrode connection portion 41 extend in the radial direction are not deformed to the maximum extent, and the curvature of the curved surface 47, the inner angle between the mating surface 48 and the first inclined surface 46, the inner angle at the connection portion between the first inclined surface 46 and the receiving surface 45, the inner angle at the connection portion between the receiving surface 45 and the second inclined surface 49, and the inner angle at the connection portion between the second inclined surface 49 and the electrode connection portion 41 are reduced.

[0227] Then, the side wall portion 11 of the cap 40 or the battery can 10 is not twisted or bent, and deformation that impairs the roundness does not occur, and the radial adhesion force between the mating surface 48 and the mating wall surface 113 can be ensured.

[0228] Referring to FIG. 20, the axial length (c-f) of the mating surface 48 is shorter than the axial length (c-e) of the mating wall surface 113. And there is a section where the inner diameter changes at the connection portion between the side wall portion 11 and the mating wall surface 113.

[0229] Between the inner peripheral surface of the side wall portion 11 and the inner peripheral surface of the butting wall surface 113, a tapered surface 115 that extends radially inward as it goes axially inward and has a substantially first inclination (m) can be provided. In the embodiment, the first inclination (m) is exemplified as being about 45 degrees.

[0230] The tapered surface 115 can be formed together when forming the butting wall surface 113.

[0231] Correspondingly, the curved surface 47 connected to the axially inner end of the butting surface 48 may be convex downward such that the inclination of the tangent to its outer peripheral surface gradually decreases as it moves away from the butting surface 48.

[0232] Referring to FIG. 21, on the outer peripheral surface of the curved surface 47, there is a point (P) where the inclination of the tangent is an angle corresponding to the first inclination (m), that is, 45 degrees.

[0233] The position (P) on the outer peripheral surface of the curved surface 47 where the inclination of the tangent corresponds to the first inclination (m) is located radially inward of the tapered surface 115. Then, as shown in FIG. 21, the inclination of the portion of the curved surface 47 facing the tapered surface 115 in the axial direction has a greater inclination than the first inclination (m) of the tapered surface 115.

[0234] Therefore, due to manufacturing tolerances of the cap 40 and the battery can 10, or because the cap 40 is inserted too far through the open end of the battery can 10, even if the outer peripheral surface of the curved surface 47 contacts the lower end portion (g; see FIG. 20) of the tapered surface 115, the inclination of the portion of the curved surface 47 in contact therewith is greater than the first inclination (m) of the tapered surface 115. Thus, the curved surface 47 can be elastically deformed and further pushed in beyond the lower end portion (g). That is, the tapered surface 115 no longer restricts the insertion depth of the cap 40.

[0235] Also, the point (P) on the curved surface 47 is located axially inward of the tapered surface 115. Then, as shown in FIG. 22, the inclination of the portion of the curved surface 47 facing the tapered surface 115 has a greater inclination than the first inclination (m) of the tapered surface 115.

[0236] The axially outer edge of the inner peripheral surface of the butting wall surface 113 and the axially outer edge of the outer peripheral surface of the butting surface 48 (see c in FIG. 20) are welded by a laser (L) irradiated in the axial direction. The irradiation direction of the laser may be aligned with the axial direction.

[0237] Then, if there is a fine gap between the butting wall surface 113 and the butting surface 48, and thus, even if the laser reaches the tapered surface 115, these lasers can change their direction in a direction further toward the axially outer side by reflecting on the tapered surface 115 and the portion of the curved surface 47 facing it.

[0238] Therefore, the insertion depth of the cap 40 is not restricted by the tapered surface 115 but is restricted by the electrode connection portion 41. Even if there is a gap (G) between the boundary portion between the tapered surface 115 and the side wall portion 11 and the curved surface 47, the laser cannot reach here, and the laser repeatedly reflects and disappears in the space between the tapered surface 115 and the curved surface 47.

[0239] Thus, the structure of the battery cell to which the cap 40 and the battery can 10 of the first embodiment are applied can prevent the joining process of the battery can 10 and the cap 40 from affecting the electrode assembly 20 housed inside the battery can 10.

[0240] Also, as described above, the height (b) of the lower end portion of the curved surface 47 is even higher than the height (a) of the bottom surface of the electrode connection portion 41. And the height of the bottom surface of the electrode connection portion 41 corresponds to the height of the tab 27 of the second electrode of the electrode assembly. Therefore, the lower end portion of the curved surface 47 is axially separated from the upper end portion of the electrode assembly. Then, even if the joining heat between the cap 40 and the battery can 10 is conducted to the curved surface 47 of the cap 40, the influence of this conducted heat on the electrode assembly 20 can be minimized.

[0241] When the lower end portion of the curved surface 47 is axially separated 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, it means that the insertion depth of the cap 40 is not restricted due to the interference between the curved surface 47 and the electrode assembly 20.

[0242] Also, due to manufacturing tolerances and assembly errors, even if the pushing-in of the cap 40 is excessive compared to the design and the outer peripheral surface of the curved surface 47 contacts the radially inner end portion of the tapered surface 115, the elastic deformation of the curved surface 47 having a steep inclination of the tangent line at the contact portion is induced. Therefore, despite manufacturing tolerances and assembly errors, the insertion depth of the cap 40 can be prevented from being restricted.

[0243] According to the embodiment, when the cap 40 is pushed into the battery can 10, the bottom surface (a; see FIG. 20) of the electrode connection portion 41 disposed further axially inward than the axially inner end portion (b; see FIG. 20) of the curved surface 47 first contacts the tab 27 of the second electrode 22 of the electrode assembly 20. Therefore, the insertion depth of the cap 40 is restricted by the electrode connection portion 41.

[0244] Thereby, when the cap 40 is pushed in, the cap 40 can be pushed in to a position where the axially inner surface of the electrode connection portion 41 is in close contact with the tab 27 of the second electrode 22 of the electrode assembly 20 housed inside the can 10.

[0245] Thus, when the cap 40 is pressed in, the electrode connection portion 41 can be in close contact with the tab of the second electrode 22. The electrode connection portion 41 and the notch tab 27 can be welded in a state of being in close contact with each other in the axial direction.

[0246] The welding of the electrode connection portion 41 and the second electrode tab 27 can be performed by a laser that irradiates the outer surface in the axial direction of the electrode connection portion 41 on the outer side in the axial direction, as shown in FIG. 19. The local heat generated by the laser irradiated on the surface of the electrode connection portion 41 can melt and join the surface of the electrode connection portion 41 and the notch tab 27 in contact with its bottom surface.

[0247] As shown in FIG. 19, the laser moves in the radial direction and irradiates the electrode connection portion 41. Thereby, the welded portion (W) of the electrode connection portion 41 extends in the radial direction. The welded portions (W) may be arranged radially or a plurality of them may be arranged at equal intervals along the circumferential direction.

[0248] The welded portion (W) extends long in the radial direction, whereby the electrode connection portion 41 may be connected to any of the notch tabs 27 of the second electrode 22 arranged from the outer peripheral side to the core side of the electrode assembly. These welding lines widen the current path, thereby greatly reducing the internal resistance of the second electrode.

[0249] When the above-described cap 40 is applied, the joining portion between the cap 40 and the battery can 10 is simplified, and when electrically connecting the tab of the second electrode 22 to the battery can 10, it is not necessary to use a current collector plate, reducing the number of parts and the assembly man-hours, further securing the internal volume, and increasing the energy density.

[0250] On the other hand, the cap 40 of the first embodiment does not include the liquid injection port 42 of the second embodiment described later.

[0251] Hereinafter, with reference to FIG. 42, a method for manufacturing a cylindrical battery cell to which the cap 40 of these first embodiments is applied will be described. However, since the manufacturing method has already been described above, hereinafter, a simplified procedure will be described.

[0252] First, prepare a battery can 10 with the first electrode terminal 13 fixed to the bottom 12, and prepare a jelly roll type electrode assembly 20 including a first electrode 21 and a second electrode 22.

[0253] Next, the electrode assembly 20 is housed in the battery can 10 such that the tab of the first electrode 21 and the current collector plate 31 of the electrode assembly 20 face the bottom 12.

[0254] Next, the first electrode 21 is joined to the first electrode terminal 13 to be electrically connected.

[0255] Then, an electrolytic solution is injected into the battery can 10.

[0256] When the injection of the electrolytic solution is completed, the cap 40 is pushed into the open end of the battery can 10, and the electrode connection portion 41 of the cap 40 is brought into close contact with and joined to the tab 27 of the second electrode 22 of the electrode assembly 20. The butting wall surface 113 of the battery can 10 and the butting surface 48 of the cap 40 are joined to electrically connect them.

[0257] [Second Embodiment] Hereinafter, with reference to FIGS. 23 to 27, a second embodiment of the cap and the structure of a battery cell to which this is applied will be described. When describing the second embodiment, the content overlapping with the first embodiment described above can be omitted. Therefore, the parts not described in any of the embodiments can be understood from other embodiments. Further, it can be easily understood that the configurations of any of the embodiments and the configurations of other embodiments can be substituted for, added to, or omitted from each other.

[0258] Compared with the first embodiment, the cap 40 of the second embodiment is further provided with a liquid injection port 42 at the central portion of the cap 40. In a state where the open end of the battery can 10 in the cap 40 is covered, the liquid injection port 42 can be aligned with the hollow portion of the winding core of the electrode assembly 20 housed in the battery can 10.

[0259] The liquid injection port 42 can be provided on a protruding portion 43 that protrudes slightly above the bottom surface of the cap 40, that is, above the electrode connection portion 41 of the cap 40. The height of the protruding portion 43 is set lower than the height of the receiving surface 45. The protruding portion 43 is connected to the centripetal side edge of the electrode connection portion 41 and has a form that extends outward in the axial direction as it goes in the centripetal direction.

[0260] The liquid injection port 42 can be finished by covering it with a plug 50. The frame portion of the plug 50 can be finished in a sealed manner with the frame portion of the liquid injection port. For this sealing finish, seam welding or various other known sealing methods can be applied.

[0261] In a state where the liquid injection port 42 is finished by covering it with the plug 50, the height of the plug 50 may also be lower than the height of the receiving surface 45. Since the plug 50 is also located lower than the receiving surface 45, even when the battery cell is standing so that the cap 40 contacts the ground, the plug 50 does not receive a direct load.

[0262] The protruding portion 43 protrudes higher than the bottom of the cap, that is, higher than the electrode connection portion. As a result, the frame portion of the liquid injection port is arranged at a distance from the tab 27 of the second electrode. Therefore, after injecting the electrolytic solution through the liquid injection port 42, covering the liquid injection port 42 with the plug 50 and joining it by a method such as welding, the joining heat is transmitted to the electrode assembly 20, and the separation membrane may be damaged. The influence that the finishing joining process of the plug 50 can have on the performance of the battery can be minimized.

[0263] The cap 40 of the first embodiment does not have a separate liquid injection port. Thus, when manufacturing a battery cell by applying the cap 40 of the first embodiment, if there is no separate liquid injection port at the bottom 12 of the battery can 10, etc., the liquid injection process of the electrolytic solution can be performed first before covering the battery can 10 with the cap 40.

[0264] However, when a liquid injection port 42 is provided in the cap 40 as in the second embodiment, even after the cap 40 is pressed into the battery can 10 to form the welded portion (W) and the joined portion (M), the electrolytic solution can be injected through the liquid injection port 42. Then, compared with joining the cap 40 to the battery can 10 in the injected state, it is possible to prevent the joining heat from affecting the electrolytic solution at all. Further, when joining around the plug 50 and the liquid injection port 42, since the protruding portion 43 protrudes upward, the possibility that the joining heat of the plug 50 affects the electrolytic solution can also be reduced.

[0265] On the other hand, the liquid injection port 42 formed at the center of the cap 40 can also serve as a passage through which the equipment configuration can enter and exit for welding the first electrode terminal 13 and the current collector plate 31 of the first electrode 21.

[0266] Thus, even after joining the cap 40 to the battery can 10, it is possible to enter the welding equipment into the battery can 10 through the liquid injection port 42 and join the first electrode 21 and the first electrode terminal 13.

[0267] Hereinafter, with reference to FIG. 43, a method for manufacturing a cylindrical battery cell to which a cap 40 provided with a liquid injection port 42 is applied as in the second embodiment will be described. However, since the manufacturing method has already been described above, hereinafter, a simplified procedure will be described.

[0268] First, prepare a battery can 10 with the first electrode terminal 13 fixed to the bottom 12, and prepare a jelly roll type electrode assembly 20 including the first electrode 21 and the second electrode 22.

[0269] Next, the electrode assembly 20 is housed in the battery can 10 such that the tab of the first electrode 21 and the current collector plate 31 of the electrode assembly 20 face the bottom 12.

[0270] Next, an operation of joining and electrically connecting the first electrode 21 to the first electrode terminal 13, and an operation of pressing the cap 40 into the open end of the battery can 10 to bring the electrode connection portion 41 of the cap 40 into close contact with and join the tab 27 of the second electrode 22 of the electrode assembly 20, and joining the butting wall surface 113 of the battery can 10 and the butting surface 48 of the cap 40 to electrically connect them are performed.

[0271] At this time, after joining the first electrode 21 to the first electrode terminal 13, the cap 40 can be pressed into the open end of the battery can 10, or after first pressing the cap 40 into the open end of the battery can 10, the first electrode 21 can be joined to the first electrode terminal 13 through the liquid injection port 42.

[0272] Next, an electrolytic solution is injected into the battery can 10 through the liquid injection port 42. When the injection of the electrolytic solution is completed, the liquid injection port 42 is covered with a plug 50 and joined by a method such as welding to finish. For the joining of the protruding portion 43 around the liquid injection port 42 and the plug 50, various methods that can be sealed and fixed can be applied.

[0273] On the other hand, the cap 40 can be joined to the tab of the second electrode 22 of the electrode assembly 20 first, as shown in FIG. 27, even before housing the electrode assembly 20 in the battery can 10. Then, the electrode assembly 20 can be housed in the battery can 10, and the cap 40 joined to the electrode assembly 20 can be inserted into the battery can 10.

[0274] That is, with the current collector plate 31 joined to the tab of the first electrode 21 of the electrode assembly 20 and the cap 40 joined to the tab of the second electrode 22, the electrode assembly 20 can be housed in the battery can 10. And the welding operation between the current collector plate 31 and the first electrode terminal 13 can be performed through the liquid injection port 42 of the cap 40 and the winding core hollow portion of the electrode assembly 20.

[0275] Hereinafter, with reference to FIG. 44, a method for manufacturing a cylindrical battery cell in the above-described manner will be described. However, since the manufacturing method has already been described above, hereinafter, a simplified procedure will be described.

[0276] First, prepare a battery can 10 with the first electrode terminal 13 fixed to the bottom 12, and prepare a jelly roll type electrode assembly 20 having a first electrode 21 and a second electrode 22.

[0277] Then, the current collector plate 31 is joined and connected to the first electrode 21 at one axial end of the electrode assembly 20, and the cap 40 is joined and connected to the second electrode 22 at the other axial end.

[0278] Next, while housing the electrode assembly 20 in the battery can 10 such that the tab of the first electrode 21 of the electrode assembly 20 and the current collector plate 31 face the bottom 12, the cap 40 is pressed into the open end of the battery can 10.

[0279] Next, a step of joining and electrically connecting the first electrode 21 to the first electrode terminal 13, and a step of joining and electrically connecting the battery can 10 and the cap 40 are performed.

[0280] Next, after injecting an electrolytic solution into the battery can 10 through the liquid injection port 42, the liquid injection port 42 is covered with a plug 50 for finishing.

[0281] In this way, when manufacturing a battery cell by applying the cap 40 provided with the liquid injection port 42, it can be configured by various manufacturing methods.

[0282] [Third Embodiment] Hereinafter, with reference to FIGS. 28 to 33, a third embodiment of the cap and the structure of a battery cell to which this is applied will be described.

[0283] The cap 40 of the third embodiment is different in the structure of the electrode connection portion 41 as compared with the first embodiment.

[0284] The electrode connection part 41 of the above-described first embodiment is in a flat disk shape, and a plurality of welding parts (W) extending in the radial direction are arranged radially on the electrode connection part 41.

[0285] On the other hand, the cap 40 of the third embodiment provides a plurality of electrode connection parts 41 corresponding to the plurality of welding parts (W). That is, the cap 40 of the third embodiment has a plurality of electrode connection parts 41 that are respectively recessed inside the battery can 10 and extend in the radial direction.

[0286] The electrode connection part 41 may be formed by press-molding the metal sheet.

[0287] The plurality of electrode connection parts 41 may be arranged radially with respect to the center of the cap 40, or may be arranged at equal intervals in the circumferential direction.

[0288] A pair of electrode connection parts 41 facing each other with respect to the center of the cap 40 are aligned in a row. The third embodiment exemplifies that four electrode connection parts 41 are provided at 90-degree intervals.

[0289] When forming a plurality of electrode connection parts 41 in these forms, an outer surface 44 that protrudes further axially outward than the electrode connection part 41 is provided between two adjacent electrode connection parts 41 in the circumferential direction. The outer surface 44 may be connected to the inner side in the radial direction of the receiving surface 45.

[0290] The protruding height of the outer surface 44 may correspond to or be lower than the protruding height of the receiving surface 45.

[0291] In the third embodiment, it is exemplified that the protruding height of the outer surface 44 corresponds to the protruding height of the receiving surface 45, and they form one plane. Then, when the battery can 10 is stood up so that the cap 40 of the battery can 10 faces the floor, the outer surface 44 may also be in contact with the floor together with the receiving surface 45.

[0292] If the height of the outer surface 44 is even lower than that of the receiving surface 45, the receiving surface 45 can provide an annular support surface.

[0293] The bottom surface of the electrode connection portion 41 is a portion that is in close contact with and joined to the notch tab 27 of the second electrode 22 of the electrode assembly 20. The electrode connection portion 41 manufactured by pressing a metal sheet may have a thickness slightly thinner than the thickness of the metal sheet before processing. Thus, when a laser is irradiated onto the surface of the electrode connection portion 41, the local heat generated by the laser can melt and join the surfaces of the electrode connection portion 41 and the notch tab 27 in contact with its bottom surface.

[0294] The electrode connection portion 41 extends in the radial direction, and the welding portion (W) for joining the electrode connection portion 41 to the notch tab 27 of the second electrode 22 of the electrode assembly 20 can have the shape of a welding line formed in the radial direction so as to correspond to the extending direction of the electrode connection portion 41.

[0295] According to the embodiment, a linear welding portion (W) extending in the radial direction is formed for each of the plurality of electrode connection portions 41.

[0296] The outer surface 44 is disposed at a position raised higher than the electrode connection portion 41 and between two circumferentially adjacent electrode connection portions 41.

[0297] Thus, by pressing the outer surfaces 44 on both sides in the circumferential direction of the electrode connection portion 41 with a jig, while bringing the electrode connection portion 41 into close contact with the notch tab 27, irradiating the surface of the electrode connection portion 41 with a laser, it is possible to weld the electrode connection portion 41 and the notch tab 27. Then, along the length direction of the welding line on both sides of the welding line, the pressure of the jig presses the electrode connection portion 41 into close contact with the notch tab 27, so that welding can be performed reliably.

[0298] A pair of electrode connection parts 41 facing each other with respect to the center of the cap 40 has a form arranged on a straight line passing through the center of the cap 40. Thus, when forming a welding line, the welding lines of the two electrode connection parts 41 aligned in a row with each other may be formed by only one movement of a laser welding machine. For example, when the first electrode connection part, the second electrode connection part, the third electrode connection part, and the fourth electrode connection part are sequentially arranged along the circumferential direction in the cap 40 of the first embodiment, the first electrode connection part and the third electrode connection part may be welded at once, and the second electrode connection part and the fourth electrode connection part may be welded at once.

[0299] Also, according to the embodiment, when the outer surface 44 provided on both sides of the first electrode connection part and the third electrode connection part arranged in a row with respect to the center of the cap 40 is pressed with a jig, since the second moment of inertia formed by the shape of the depression of the second electrode connection part and the fourth electrode connection part is large, the cap 40 can move as a rigid body without being twisted or bent despite the pressure of the jig.

[0300] In the embodiment, as described above, by configuring the four electrode connection parts 41, all of the four electrode connection parts 41 can be welded with the locus of two laser scans.

[0301] If the number of the electrode connection parts 41 is too large for processing, the strength of the cap 40 made of a metal sheet may be weakened. Also, if only two or three electrode connection parts 41 are formed, it is difficult to configure a cross-section for sufficiently ensuring the second moment of inertia along the circumferential direction.

[0302] As in the embodiment, when the four electrode connection parts 41 are configured in a “+” shape on the cap 40, the welding process can be performed accurately and simply, the torsional resistance and bending resistance of the cap 40 can be ensured, and it is also possible to prevent the strength of the cap 40 from being weakened by the forming process. Thus, the cap 40 of the third embodiment can further sufficiently ensure the welding strength with the second electrode 22 through the plurality of electrode connection parts 41.

[0303] In addition, since the loads received by the plurality of outer surfaces 44 provided between the electrode connection portions 41 in the circumferential direction act in the direction of crimping the electrode connection portion 41 and the tab of the second electrode 22 against each other, the protection effect of the welded portion (W) of the cap 40 and the notch tab 27 is further improved.

[0304] [Fourth Embodiment] Hereinafter, with reference to FIGS. 34 to 41, a fourth embodiment of the cap and the structure of a battery cell to which this is applied will be described.

[0305] First, the cap of the fourth embodiment is different from that of the second embodiment in the structure of the electrode connection portion 41. Further, the cap of the fourth embodiment is different from that of the third embodiment in that a liquid injection port 42 is provided at the center of the cap 40.

[0306] The outer surface 44 of the cap 40 of the fourth embodiment projects further in the axial direction than the protruding portion 43 that defines the liquid injection port 42. And the protruding portion 43 is directly connected to the outer surface 44 in the radial direction.

[0307] Then, as shown in FIG. 38, in order to finish the liquid injection port 42, a heat conduction path is formed so that the heat generated when joining the plug 50 is not conducted to the electrode assembly but is immediately conducted to the outer surface 44. Therefore, the phenomenon that the joining heat affects the electrode assembly 20 can be further reduced.

[0308] Also, although the same applies to the structure of the cap of the third embodiment, as shown in FIG. 39, since the outer surfaces 44 are adjacent to both sides of the electrode connection portion 41 in the circumferential direction, the heat generated when welding the metal foil 23 of the electrode connection portion 41 and the second electrode 22 is dissipated through the outer surfaces 44 on both sides thereof, and the phenomenon that the joining heat affects the electrode assembly 20 can be further reduced.

[0309] Next, the cap 40 of the fourth embodiment is different from the first to third embodiments in that it further includes a vent 60.

[0310] The vent 60 is provided along the circumferential direction on the outer side in the radial direction with respect to the electrode connection portion 41. In the fourth embodiment, it is exemplified that the vent 60 is provided on the receiving surface 45. The vent 60 is embodied in a soft or thin portion where both surfaces of the receiving surface 45 are notched.

[0311] The strength of the vent 60 has a strength that does not deform under the force applied when the cap 40 is pressed into the battery can 10, and breaks when the internal pressure rapidly increases due to a short circuit or the like generated inside the battery can 10, separating the electrode connection portion 41 of the cap 40 and the butting surface 48 of the cap 40. Thereby, the electrical connection between the electrode connection portion 41 connected to the tab of the second electrode 22 and the battery can 10 is cut, the internal space of the battery can 10 is opened to the outside, and the gas causing the pressure resistance is discharged.

[0312] The vent 60 can be provided near the central portion of the receiving surface 45 in the radial direction so as to be separated from the first inclined surface 46 and the second inclined surface 49 in the radial direction.

[0313] Then, even when the receiving surface 45 is pressurized, the pressure is transmitted to the first inclined surface 46 and the second inclined surface 49 and does not affect the vent 60. Therefore, the force applied when joining the cap 40 to the battery can 10 and the electrode assembly 20 does not deform the vent 60.

[0314] The vent 60 is provided on the outer side in the radial direction with respect to the outer surface 44. And these outer surfaces 44 are provided between the electrode connection portions 41 in the circumferential direction. Also, a space corresponding to the height difference between the outer surface 44 and the electrode connection portion 41 is provided inside the outer surface 44 in the axial direction (see FIG. 38 etc.).

[0315] Therefore, when the pressure resistance of the battery can 10 increases, these pressures are smoothly transmitted to the lower space of the outer surface 44 disposed between the electrode connection portions 41 in the circumferential direction and act as a force to lift the outer surface 44 upward. Further, the action of these forces occurs concentrated at four locations along the circumferential direction. Therefore, the pressure resistance of the battery can 10 can be smoothly transmitted to the vent 60, leading to a smooth breakage of the vent 60.

[0316] In the fourth embodiment, an example is illustrated in which the vent 60 is provided in the shape of a thin-walled portion on the receiving surface 45. However, the vent 60 constituted by the cap 40 is not limited thereto. For example, the vent can also be provided on the plug 50 covering the liquid injection port 42, can also be constituted by the joint portion between the liquid injection port 42 and the plug 50, and can also be constituted by the joint portion (M) between the cap 40 and the battery can 10.

[0317] That is, according to the embodiment, by embodying the vent structure on the cap 40 itself or the joint portion between the cap 40 and other components, it is possible not to secure a separate volume for the vent structure. Thereby, the energy density of the battery cell can be further increased.

[0318] [Battery Pack and Vehicle] Referring to FIG. 45, the battery cell 72 to which the above-described cap is applied and / or the battery cell 72 to which the above-described manufacturing method is applied can be accommodated in the housing 71 of the battery pack 70. The battery pack 70 can also be configured using a battery module which is an intermediate form of assembly, or as shown in the figure, the battery pack 70 can be directly configured without a battery module.

[0319] Since the above-described battery cell 72 is large in volume by itself, there is no difficulty in implementing the battery pack 70 without using an intermediate structure called a battery module. And since the second electrode of the battery cell 72 is connected via a cap, the internal resistance is also small and the energy density is even higher. Also, since the structure of the vent 60 is provided in the cap 40 and does not occupy a separate space, the energy density can be further ensured. As a result, the energy density of the battery pack 70 equipped with the battery cell 72 can be implemented even higher.

[0320] In this way, the battery pack 70 with increased energy density can store the same energy and can reduce its volume and load. Therefore, when the battery pack 70 to which these battery cells 72 are applied is mounted on a vehicle such as an automobile 80 using electricity as an energy source as shown in FIG. 46, the mileage of the vehicle with respect to energy can be further expanded.

[0321] It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention is shown by the claims described below rather than the above detailed description. And of course, all changes and deformable forms derived from the equivalent concept of the meaning and scope of the claims described below should be construed as being included in the scope of the present invention.

[0322] As described above, the present invention has been described with reference to the exemplary drawings, but the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by those skilled in the art within the scope of the technical idea of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

Description of Reference Numerals

[0323] 10 Battery can 11 Side wall 111 Pressing guide surface 113 Butting wall surface (c-e) 115 Tapered surface m First inclination 12 Bottom 13 Positive electrode terminal (first electrode terminal) 14 Terminal gasket 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 Grounded part 26 Ungrounded part 27 Notched tab 28 Separator 31 Current collector 32 Terminal connection part 33 Ring part 34 Electrode connection part 40 Cap 41 Electrode connection part W Welding part 42 Liquid injection port 43 Protrusion 44 Outer surface 45 Receiving surface 46 First inclined surface 47 Curved surface (b-f) P Position where the inclination of the connection line is the first inclination G Gap 48 Butting surface (c-f) M Joint part 49 Second inclined surface 50 Plug 60 Vent 70 Battery pack 71 Housing 72 Battery cell 80 Vehicle (automobile)

Claims

1. A battery can 10 having a side wall portion 11 with an open end provided on one side in the axial direction; An electrode assembly 20 including a first electrode 21 and a second electrode 22 and housed inside the battery can 10 such that the tab of the second electrode 22 faces the open end; and A cap 40 covering the open end of the battery can 10 and connected to the second electrode 22; The side wall portion 11 is provided at the open end of the side wall portion 11, extends axially outward, and has a butting wall surface 113 whose inner diameter is larger than the inner peripheral surface of the side wall portion 11; The cap 40 has a butting surface 48 extending in the axial direction such that the outer peripheral surface thereof contacts the inner peripheral surface of the butting wall surface 113, and an electrode connection portion 41 electrically connected to the tab of the second electrode 22; The outer axial edge of the inner peripheral surface of the butting wall surface 113 and the outer axial edge of the outer peripheral surface of the butting surface 48 are joined; A battery cell.

2. The pushing-in depth of the cap 40 with respect to the battery can 10 is defined by the connection portion between the electrode connection portion 41 of the cap 40 and the tab of the second electrode 22 housed in the battery can 10. The battery cell according to claim 1.

3. The axial length (c - f) of the butting surface 48 is shorter than the axial length (c - e) of the butting wall surface 113. The battery cell according to claim 1 or 2.

4. The connection portion between the side wall portion 11 with a changing inner diameter and the butting wall surface 113 does not regulate the pushing-in depth of the tab 27 with respect to the battery can 10. The battery cell according to any one of claims 1 to 3.

5. At the connection portion between the side wall portion 11 and the butting wall surface 113, a tapered surface 115 is provided which extends radially inward as it goes axially inward, and whose inclination is substantially constant at a first inclination (m). At the inner axial end of the butting surface 48, a curved surface 47 is connected which extends radially inward as it goes axially inward, and the inclination of the tangent to its outer peripheral surface gradually decreases. The battery cell according to any one of claims 1 to 4.

6. The position (P) where the inclination of the tangent to the outer peripheral surface of the curved surface 47 corresponds to the first inclination (m) satisfies at least one of a first condition of being radially inner than the tapered surface 115 and a second condition of being axially inner than the tapered surface 115. The battery cell according to claim 5.

7. On the inner side in the radial direction of the butting surface 48 in the cap 40, a receiving surface 45 that extends flat in the radial direction is provided. The outer surface in the axial direction of the receiving surface 45 is arranged further axially outside than the outer end in the axial direction of the butting surface 48. The receiving surface 45 is connected to the butting surface 48 via a curved surface 47 provided at the inner end in the axial direction of the butting surface 48. The battery cell according to any one of claims 1 to 6.

8. Between the curved surface 47 and the receiving surface 45, a first inclined surface 46 is provided that extends axially outward as it goes radially inward and has a substantially constant inclination. The battery cell according to claim 7.

9. The electrode connection portion 41 is provided at a position sunken axially inside in the radial direction relative to the receiving surface 45. The inner surface in the axial direction of the electrode connection portion 41 is arranged further axially inside than the inner end in the axial direction of the curved surface 47. The battery cell according to claim 7 or 8.

10. Between the electrode connection portion 41 and the receiving surface 45 in the radial direction, a second inclined surface 49 is provided that extends axially inward as it goes radially inward and has a substantially constant inclination. The battery cell according to claim 9.

11. A current collector plate 35 is joined to the tab of the second electrode 22 and electrically connected. The electrode connection portion 41 is joined to the current collector plate 35 and electrically connected to the tab of the second electrode 22. The battery cell according to claim 9 or 10.

12. The electrode connection portion 41 is directly joined to the tab of the second electrode 22 and electrically connected. The battery cell according to any one of claims 9 to 11.

13. The joining portion between the electrode connection portion 41 and the tab of the second electrode 22 extends in the radial direction. The battery cell according to claim 12.

14. The electrode connection portion 41 and the tab of the second electrode 22 are joined by a welded portion (W) formed by laser irradiated on the surface of the electrode connection portion 41 along the radial direction. The battery cell according to claim 12 or 13.

15. A liquid injection port 42 is provided at the central portion of the electrode connection portion 41. The battery cell according to any one of claims 1 to 14.

16. The liquid injection port 42 is provided at a protruding portion 43 that protrudes further axially outside than the electrode connection portion 41 around the liquid injection port 42. The battery cell according to claim 15.

17. On the inner side in the radial direction of the mating surface 48 in the cap 40, a receiving surface 45 extending flat in the radial direction is provided. A plurality of the electrode connection portions 41 are provided on the inner side in the radial direction of the receiving surface 45. The plurality of electrode connection portions 41 are each recessed inside the battery can 10 and extend in the radial direction. The battery cell according to any one of claims 1 to 16.

18. The plurality of electrode connection portions 41 are arranged radially with respect to the center of the cap 40. The battery cell according to claim 17.

19. The electrode connection portions 41 are arranged at equal intervals in the circumferential direction. The battery cell according to claim 17.

20. Four electrode connection portions 41 are provided at intervals of 90 degrees. The battery cell according to claim 17.

21. A pair of electrode connection portions 41 facing each other with respect to the center of the cap 40 are aligned in a row. The battery cell according to claim 17.

22. Between two adjacent electrode connection portions 41 in the circumferential direction, an outer surface 44 protruding further axially outside than the electrode connection portions 41 is provided. The outer surface 44 is connected to the inner side in the radial direction of the receiving surface 45. The battery cell according to claim 17.

23. The protruding height of the outer surface 44 corresponds to or is lower than the protruding height of the receiving surface 45. The battery cell according to claim 22.

24. At the central portion of the electrode connection portion 41, a protruding portion 43 protruding further axially outside than the electrode connection portion 41 is provided, and a liquid injection port 42 is provided in the protruding portion 43. The outer surface 44 protrudes further axially than the protruding portion 43. The battery cell according to claim 22.

25. The protruding portion 43 is connected to the inner side in the radial direction of the outer surface 44. The battery cell according to claim 24.

26. The cap 40 is provided with a vent 60. The vent 60 is provided on the outer side in the radial direction of the electrode connection portion 41. The battery cell according to any one of claims 1 to 25.

27. On the inner side in the radial direction of the mating surface 48 in the cap 40, a receiving surface 45 extending flat in the radial direction is provided. The electrode connection portion 41 is provided at a position recessed axially from the inner side in the radial direction of the receiving surface 45. The vent 60 is provided at the center of the receiving surface 45 in the radial direction. The battery cell according to claim 26.

28. The tab of the second electrode 22 is provided in a form in which the metal foil 23 of the second electrode 22 exposed at the other end in the axial direction of the electrode assembly 20 is bent and overlapped in the radial direction. The battery cell according to claim 17.

29. The battery can 10 further includes a bottom portion 12 connected to the other end in the axial direction of the side wall portion 11; A first electrode terminal 13 that is electrically insulated and fixed to the bottom portion 12 of the battery can 10 is attached to the bottom portion 12 of the battery can 10. The first electrode 21 of the electrode assembly 20 is connected to the first electrode terminal 13 via a current collector plate 31 provided at the other end in the axial direction of the electrode assembly 20. The battery cell according to any one of claims 1 to 28.

30. Preparing a battery can 10 including a side wall portion 11, a bottom portion 12 connected to one end in the axial direction of the side wall portion 11, and an open end portion provided at the other end in the axial direction of the side wall portion 11, forming a butting wall surface 113 with an expanded inner diameter at the other end of the side wall portion 11, and sealing and insulatingly fixing a first electrode terminal 13 at the center of the bottom portion 12; Preparation stage of the battery can; Preparing an electrode assembly 20 including a first electrode 21 and a second electrode 22, wherein the tabs of the first electrode 21 and the second electrode 22 are respectively arranged on both sides in the axial direction; Preparation stage of the electrode assembly; Preparing a cap 40 including a butting surface 48 extending in the axial direction and an electrode connection portion 41 electrically connected to the tab of the second electrode 22, such that the outer peripheral surface contacts the inner peripheral surface of the butting wall surface 113; Preparation stage of the cap; After the preparation stage of the battery can and the preparation stage of the electrode assembly, an accommodation stage of the electrode assembly in which the electrode assembly 20 is accommodated in the battery can 10 such that the tab of the first electrode 21 faces the bottom portion 12 of the battery can 10; After the accommodation stage of the electrode assembly, a connection stage of the first electrode terminal for connecting the tab of the first electrode 21 and the first electrode terminal 13; After the connection stage of the first electrode terminal, a liquid injection stage of injecting an electrolyte into the battery can 10; and After the preparation stage of the cap and the liquid injection stage, a pressing-in stage of the cap in which the cap 40 is pressed into the open end portion of the battery can 10 to bring the electrode connection portion 41 into close contact with the tab of the second electrode 22; and After the step of pressing the cap, a fixing step of the cap is included, in which the electrode connecting portion 41 is joined to the tab of the second electrode 22 to be electrically connected, and the outer peripheral surface of the butting surface 48 is joined to the inner peripheral surface of the butting wall surface 113 to be electrically connected. A method for manufacturing a battery cell.

31. Prepare a battery can 10 including a side wall portion 11, a bottom portion 12 connected to one axial end of the side wall portion 11, and an open end provided at the other axial end of the side wall portion 11. A preparation step of the battery can is included, in which a butting wall surface 113 with an expanded inner diameter is formed at the other end of the side wall portion 11, and a first electrode terminal 13 is sealed and insulated and fixed at the center of the bottom portion 12. A preparation step of an electrode assembly is included, in which an electrode assembly 20 including a first electrode 21 and a second electrode 22 is prepared, and the tabs of the first electrode 21 and the second electrode 22 are respectively arranged on both axial sides. A preparation step of a cap is included, in which a cap 40 is prepared, which includes a butting surface 48 extending in the axial direction such that the outer peripheral surface thereof contacts the inner peripheral surface of the butting wall surface 113, an electrode connecting portion 41 electrically connected to the tab of the second electrode 22, and a liquid injection port 42 provided at the central portion of the electrode connecting portion 41. After the preparation step of the battery can and the preparation step of the electrode assembly, an accommodation step of the electrode assembly is included, in which the electrode assembly 20 is accommodated in the battery can 10 such that the tab of the first electrode 21 faces the bottom portion 12 of the battery can 10. After the accommodation step of the electrode assembly, a connection step of the first electrode terminal is included, in which the tab of the first electrode 21 and the first electrode terminal 13 are connected. A pressing step of the cap is included, in which the cap 40 is pressed into the open end of the battery can 10 to bring the electrode connecting portion 41 into close contact with the tab of the second electrode 22. After the pressing step of the cap, a fixing step of the cap is included, in which the electrode connecting portion 41 is joined to the tab of the second electrode 22 to be electrically connected, and the outer peripheral surface of the butting surface 48 is joined to the inner peripheral surface of the butting wall surface 113 to be electrically connected. And After the connection step of the first electrode terminal and the fixing step of the cap, a step is included, in which an electrolytic solution is injected into the battery can 10 through the liquid injection port 42, and the liquid injection port 42 is sealed and finished. A method for manufacturing a battery cell.

32. Prepare a battery can 10 including a side wall portion 11, a bottom portion 12 connected to one axial end of the side wall portion 11, and an open end provided at the other axial end of the side wall portion 11. Form a butting wall surface 113 with an expanded inner diameter at the other end of the side wall portion 11, and seal and insulate and fix a first electrode terminal 13 at the center of the bottom portion 12; this is the preparation stage of the battery can. Prepare an electrode assembly 20 including a first electrode 21 and a second electrode 22, with the tabs of the first electrode 21 and the second electrode 22 arranged on both axial sides respectively; this is the preparation stage of the electrode assembly. Prepare a cap 40 including a butting surface 48 extending in the axial direction such that its outer peripheral surface contacts the inner peripheral surface of the butting wall surface 113, an electrode connection portion 41 electrically connected to the tab of the second electrode 22, and a liquid injection port 42 provided at the central portion of the electrode connection portion 41; this is the preparation stage of the cap. After the preparation stage of the electrode assembly and the preparation stage of the cap, join the electrode connection portion 41 of the cap 40 to the tab of the second electrode 22 and electrically connect them; this is the connection stage of the second electrode. After the preparation stage of the battery can and the connection stage of the second electrode, accommodate the electrode assembly 20 in the battery can 10 such that the tab of the first electrode 21 faces the bottom portion 12 of the battery can 10, and press the cap 40 into the open end of the battery can 10; this is the accommodation stage of the electrode assembly and the pressing-in stage of the cap. After the accommodation stage of the electrode assembly and the pressing-in stage of the cap, connect the tab of the first electrode 21 and the first electrode terminal 13, and join the outer peripheral surface of the butting surface 48 to the inner peripheral surface of the butting wall surface 113 and electrically connect them; this is the connection stage of the first electrode terminal and the fixing stage of the cap; and After the connection stage of the first electrode terminal and the fixing stage of the cap, inject electrolyte into the battery can 10 through the liquid injection port 42, and seal and finish the liquid injection port 42; this includes the Method for manufacturing a battery cell.

33. A battery pack including the battery cell according to any one of Claims 1 to 29. Battery pack.

34. An automobile comprising the battery pack according to Claim 33. Automobile.

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