Sealing structure for filling port of battery can, battery cell, battery, and vehicle having the same

Abstract

One aspect of the present invention relates to a structure for sealing a filler hole of a battery cell. The battery cell includes a can having an open end at one axial end; an electrode assembly accommodated inside the can; a cap covering the open end of the can; a filler hole provided in the cap; and a finishing member inserted into the filler hole to finish the filler hole. The finishing member is inserted into the filler hole and sealed and fixed thereto via a sealing and fixing material that melts at a predetermined temperature. The finishing member includes a metal ball. The sealing and fixing material may include a synthetic resin layer coated on the surface of the ball, or may include solder that fills the gap between the surface of the ball and the inner circumferential surface of the filler hole when the ball is inserted into the filler hole, sealing and fixing the ball inside the filler hole.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0124981 filed on September 30, 2022 and Korean Patent Application No. 10-2023-0026246 filed on February 27, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a structure for sealing a filler hole in a cap of a battery can, a battery cell to which the structure is applied, a method for manufacturing the battery cell, a battery pack including the battery cell, and an automobile equipped with the battery pack. [Background technology]

[0003] Cylindrical battery cells have a structure in which a jelly-roll-type electrode assembly is housed inside a cylindrical metal can, and are more resistant to shock and temperature than pouch-type batteries. For this reason, there is an increasing demand for metal can-type cells as battery cells for vehicle battery packs.

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

[0005] The open end of the battery can is covered with a cap, and the cap and the battery can are fixed together by crimping or seam welding.

[0006] Referring to FIG. 1 , crimping is a method of securing the cap 40 by physically crimping the edge of the cap 40 to the open end of the can 10 with a gasket 91 interposed therebetween. Because crimping is a physical securing method that does not require the application of heat, it is possible to perform the process even when the can is filled with electrolyte. Therefore, the crimping method has the advantage of eliminating the need for a separate filling port and a sealing structure. However, crimping is structurally more complex than welding, and there is a limit to the internal volume of the can that can accommodate the electrode assembly 20.

[0007] In contrast, as shown in Figure 2, seam welding is a method of butting the periphery of the front end of the side wall 11 of the battery can 10 against the periphery of the cap 40 and welding them together in the circumferential direction. This simple fixing structure allows for a larger volume of the electrode assembly to be accommodated inside the battery can. Therefore, the seam welding method is more advantageous in ensuring a larger electrical capacity for the same volume of the battery can.

[0008] However, when the open end of the battery can is covered with a cap and welded after filling the battery can with electrolyte, the high temperature generated by welding may cause the electrolyte to deteriorate or ignite.

[0009] For example, if the can and cap are made of stainless steel, the surface temperature can rise to 1,400 degrees Celsius, which is the melting point of stainless steel. This high temperature can cause the electrolyte to ignite.

[0010] Therefore, when seam welding the periphery of the open end of the battery can and the cap, a method can be applied in which a battery can 10 having a filler hole at the bottom or a cap 40 having a filler hole 42 is prepared, an electrode assembly is placed inside the battery can, the battery can 10 and the cap 40 are seam-welded, and then an electrolyte is poured through the filler hole 42 at the bottom of the cap or the battery can, and after the pouring is completed, the filler hole is sealed to finish the process.

[0011] 2, a finishing member such as a metal ball 50 can be forcibly pressed into the filling port 42 to seal and fix the filling port 42. In this method, a metal ball 50 having a diameter larger than the inner circumferential surface of the filling port 42 is forcibly pressed into the filling port 42, and the inner circumferential surface of the filling port 42 and the metal ball 50 are pressed against each other due to elastic deformation of these surfaces, thereby achieving a seal.

[0012] However, this structure is disadvantageous in terms of securing the internal volume of the can, since the sealing structure of the liquid filling hole occupies the volume of the battery cell for the section where the ball is pushed in. Also, forcibly inserting the ball 50 into the liquid filling hole 42 applies a large load to the electrode, which may damage the electrode.

[0013] Meanwhile, if thermal runaway occurs inside a battery cell can, the internal pressure of the can increases, causing an explosion. To prevent this explosion, a vent structure can be applied to the can or cap. A typical vent structure works on the principle that when the internal temperature of the can rises due to thermal runaway, and the internal pressure of the can increases, the increased pressure breaks a weak part 92 in the can or cap, releasing the internal pressure. These weak parts are formed by forming notches 92 in predetermined locations on the can or cap, as shown in FIG. 1, to make the areas easily breakable.

[0014] However, even if the cap welding method, which is advantageous in terms of further securing the internal volume of the can capable of accommodating the electrode assembly, is applied, there is an irony in that the internal volume of the can capable of accommodating the electrode assembly is further reduced because the aforementioned separate filling hole, its finishing structure, and vent structure occupy the internal volume of the can.

[0015] Meanwhile, a vent structure may be implemented through the inlet. In this case, since the inlet has a small area, the finishing member closing the inlet is unlikely to be damaged by pressure, causing the finishing member to lose its sealing strength. Therefore, when high temperatures are generated inside the battery cell, it is possible to apply a finishing member that loses its sealing strength due to the heat generated.

[0016] However, materials with low melting points, such as synthetic resins, usually have low rigidity and strength, and therefore have a weak sealing and fixing force. Therefore, using such materials alone as finishing members results in a very unstable finishing method for the pouring port. Summary of the Invention [Problem to be solved by the invention]

[0017] One aspect of the present invention has been devised to solve the above-mentioned problems, and aims to provide a safety device for a battery cell that allows electrolyte to be poured through a pouring port, allows seam welding of the cap, and allows the pouring port itself to function as a vent structure without the need for a separate vent structure.

[0018] Another aspect of the present invention is to provide a battery cell structure in which the filling port and its finishing structure do not occupy a space in which the electrode assembly can be accommodated, thereby maximizing the internal volume of the can in which the electrode assembly can be accommodated.

[0019] Another aspect of the present invention is to provide a battery cell structure that allows the electrolyte to fill smoothly when pouring into the can.

[0020] Another aspect of the present invention is to provide a sealing structure for a liquid inlet that can seal the liquid inlet without applying strong force or high heat when sealing the liquid inlet, and a battery cell to which this is applied.

[0021] Another aspect of the present invention is to provide a sealing structure for a liquid inlet that has excellent sealing finish for the liquid inlet and that also allows smooth discharge of gas when venting is required.

[0022] Another embodiment of the present invention is to provide a battery cell with high energy density and a vehicle equipped with a battery pack using the battery cell.

[0023] The technical object of the present invention is not limited to the above-mentioned objects, and other unmentioned objects and advantages of the present invention can be understood from the following description and can be more clearly understood from the examples of the present invention. Furthermore, it can be easily understood that the objects and advantages of the present invention can be achieved by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0024] In order to solve the above-mentioned problems, one aspect of the present invention provides a filling port finishing structure applicable to a battery cell, which includes a filling port provided in a can or a cap, and a finishing member inserted into the filling port to finish the filling port.

[0025] The can of the battery cell may have an open end at one end in an axial direction, an electrode assembly may be accommodated inside the can, and the cap may cover the open end of the can in which the electrode assembly is accommodated.

[0026] The finishing member is inserted into the pouring hole and sealed and fixed thereto via a sealing and fixing material having a melting point that melts at a predetermined temperature.

[0027] The melting point may be a temperature at which the battery cell melts due to heat generated by thermal runaway. The melting point may be a temperature lower than the melting points of the finish, cap, and can. These temperatures may be between 100°C and less than 500°C.

[0028] The finishing member is firmly fixed in the liquid inlet via a sealing fastener, and can be easily removed from the liquid inlet without the sealing fastener.

[0029] The finish, cap and can may be made of metal.

[0030] The finishing member may be a ball.

[0031] The sealing material may include a synthetic resin layer coated on the surface of the ball.

[0032] When the ball is inserted into the inlet, the sealing and fixing material is pressed between the inner circumferential surface of the inlet and the surface of the ball, thereby sealingly fixing the ball inside the inlet.

[0033] If thermal runaway occurs in the battery cell, the synthetic resin layer may melt, causing the sealing function achieved by the compression of the synthetic resin layer to be lost, and the high-pressure gas inside the can may be released to the outside through the filling hole.

[0034] The sealing and fixing material may include solder that fills the space between the surface of the ball and the inner surface of the liquid injection port when the ball is inserted into the liquid injection port, thereby sealing and fixing the ball inside the liquid injection port.

[0035] The solder may be lead-free solder.

[0036] When thermal runaway occurs in the battery cell, the solder melts, causing the solder to become unable to withstand the internal pressure of the can, and the high-pressure gas inside the can can then be released to the outside through the inlet.

[0037] The diameter of the ball may be equal to or smaller than the inner diameter of the pouring hole, so that when the sealing fastener is heated and loses its sealing force, high-pressure gas inside the can may be released into the gap between the inner circumferential surface of the pouring hole and the ball.

[0038] The liquid inlet may include a circular tube extending in the axial direction, the circular tube extending inside a hollow portion of the winding core of the electrode assembly, and the ball may be inserted into the circular tube and hermetically fixed therein.

[0039] As a result, the axial length of the electrode assembly can be further ensured despite the inlet structure and the vent structure, and therefore the energy density relative to the volume of the battery cell can be further ensured.

[0040] The circular tube may be provided with an air hole through which air inside the can is discharged when the electrolyte is poured through the pouring hole.

[0041] During the injection process, the lower end of the circular tube is positioned lower than the upper end of the electrode assembly. As a result, air inside the can may be trapped in the space between the peripheral wall of the can and the circular tube, forming an air pocket. This may prevent the electrolyte from smoothly impregnating the electrode assembly portion in the space.

[0042] The air hole may be formed in the circular tube above the upper end of the electrode assembly, so that when the electrolyte is poured, the space can be smoothly filled with the electrolyte without forming an air pocket.

[0043] After the liquid injection is completed and a ball is inserted into the liquid injection port, these air holes may be sealed by the sealing fixing material that seals the gap between the inner circumferential surface of the liquid injection port and the surface of the ball.

[0044] The air hole may be sealed by the solder. The diameter of the air hole may be such that the solder does not flow into the interior through the air hole due to the viscosity and surface tension of the solder while allowing air to flow through the air hole.

[0045] In order to solve the above-mentioned problems, one aspect of the present invention provides a battery cell including: a can having an open end at one side end; an electrode assembly housed inside the can; a cap covering the open end of the can; a liquid filling port provided on the can or the cap; a finishing member inserted into the liquid filling port; and a sealing fixing member that fixes the finishing member inserted into the liquid filling port within the liquid filling port.

[0046] The liquid filling port has a through section extending in a first direction that crosses the outside and inside of the battery cell, and has a through cross section defined by the intersection of a virtual plane extending in a second direction that intersects with the first direction and the inner surface of the liquid filling port.

[0047] The finishing member extends in the first direction and has a finishing cross section defined by an intersection between an imaginary plane extending in the second direction and an outer circumferential surface of the finishing member.

[0048] At least a portion of the finishing member in the first direction is disposed within the through-section of the pouring hole.

[0049] The sealing fixing material is interposed between the inner circumferential surface of the pouring port and the outer circumferential surface of the finishing member in the second direction.

[0050] The sealing fixing material blocks the space between the inner surface of the pouring port and the outer surface of the finishing member in a sealed section, which is at least a portion of the section in the first direction, and fixes the finishing member within the pouring port.

[0051] The sealing fixing material has a melting point lower than that of the can or cap on which the pouring spout is provided and that of the finishing member.

[0052] The minimum size of the through cross section of the inlet is smaller than the maximum size of the finishing cross section of the finishing member, and the position in the first direction where the through cross section of the inlet has the minimum size may be located further inside than the sealed section.

[0053] This prevents the finishing member from falling into the can through the pouring opening.

[0054] The pouring port may be defined by the inner circumferential surface of a circular tube extending in a first direction from the can or cap.

[0055] This makes it possible to ensure a sufficient section in the first direction in which the sealing fixing material is interposed to fix the finishing member inserted into the pouring port.

[0056] An inner end portion of the circular tube in the first direction may extend in the axial direction so as to be inserted into a hollow portion of a winding core of the electrode assembly.

[0057] This allows the circular tube to avoid occupying space in the axial direction of the battery cell, further increasing the energy density of the battery cell.

[0058] The circular tube may be provided with an air hole through which air inside the can is discharged when the electrolyte is poured through the pouring hole.

[0059] The air hole may be disposed in the sealed section, so that the air hole can be sealed during the process of finishing the filling hole after filling, without the need to separately block the air hole.

[0060] The outer peripheral surface of the finishing member does not need to be in direct contact with the inner peripheral surface of the liquid inlet, thereby ensuring a space between the finishing member and the inner peripheral surface of the liquid inlet for venting the battery cell when the sealing and fixing material loses its sealing and fixing force.

[0061] The sealing fixing material may be connected to an outer peripheral surface of the finishing member in the sealed section and may be in contact with an inner peripheral surface of the pouring port.

[0062] The sealing fixture may be provided by being integrally fixed to the outer circumferential surface of the finishing member.

[0063] The sealing and fixing material may include a synthetic resin layer coated on the surface of the finishing member.

[0064] The elastic modulus of the sealing fastener may be less than the elastic modulus of the finishing member.

[0065] The elastic modulus of the sealing fixing material may be lower than the elastic modulus of a member that constitutes the inner circumferential surface of the liquid pouring hole.

[0066] The finishing member may be made of a metal material.

[0067] The sealing fixture may have a sealing cross section defined by an intersection between an imaginary plane extending in the second direction and an outer circumferential surface of the sealing fixture.

[0068] The sealing cross-section of the sealing fastener disposed in the sealed section may be larger than the through-section of the inlet of the sealed section, and may be compressed inward in the second direction by the inner circumferential surface of the inlet, thereby shrinking to correspond to the through-section.

[0069] During the compression process of the sealing fastener, the member that defines the inner circumferential surface of the liquid pouring hole is hardly deformed.

[0070] During the compression of the sealing fastener, the finishing member is hardly deformed.

[0071] The sealant may include a section inward in the first direction from the sealed section, the section having a gradually smaller sealed cross section as it moves inward in the first direction, so that when the finishing member is pushed into the pouring hole, the sealant can be smoothly inserted into the pouring hole, and the pushing can naturally elastically compress the sealant in the second direction.

[0072] The inner end of the sealing material in the first direction can cover the finishing element in the first direction, thereby preventing the sealing material from being detached from the surface of the finishing element due to a tensile force in the first direction when the finishing element is pressed in.

[0073] The finishing member may include a section, located more inward in the first direction than the sealing section, in which the finishing cross section gradually becomes smaller as it goes further inward in the first direction, thereby ensuring the thickness of the sealing material and preventing the sealing material from being torn by a tensile force in the first direction when the finishing member is pressed in.

[0074] The finishing member may be a ball, and the sealing material may be integrally provided by coating the ball with a predetermined thickness.

[0075] In the sealed section, an inner circumferential surface of the liquid pouring port may extend so as to be aligned in the first direction. That is, a through cross section of the liquid pouring port in the sealed section may be constant along the first direction.

[0076] The through cross section and the finished cross section may be circular.

[0077] The sealing cross section may be circular.

[0078] The outer peripheral surface of the finishing member may be in contact with the inner peripheral surface of the liquid pouring port.

[0079] The outer peripheral surface of the finishing member and the inner peripheral surface of the liquid pouring port may be in line contact in the circumferential direction.

[0080] When the finishing member is pressed firmly into the pouring port, at least one of the inner circumferential surface of the finishing member and the pouring port is elastically deformed, allowing the finishing member and the pouring port to come into surface contact in the circumferential direction.

[0081] In contrast, when the finishing member is lightly inserted into the inlet, for example, when the finishing member is inserted into the inlet with a force equal to or slightly greater than the force of gravity, the finishing member is inserted into the inlet until it comes into contact with the inner surface of the inlet, so that the finishing member and the inner surface of the inlet do not substantially elastically deform, and the finishing member and the inlet can come into line contact in the circumferential direction.

[0082] The outer peripheral surface of the finishing member and the inner peripheral surface of the liquid pouring port may be in contact with each other in a section where the through cross section of the liquid pouring port gradually decreases toward the inside in the first direction.

[0083] This ensures that a space for venting can be secured between the finishing member and the inner peripheral surface of the pouring port when the sealing and fixing material loses its sealing and fixing force.

[0084] The inclination of the inner surface of the pouring port may be constant in a predetermined section inward in the first direction from the position where the outer surface of the finishing member and the inner surface of the pouring port meet and in a predetermined section outward in the first direction.

[0085] The liquid pouring port and the finishing member may correspond to the shape of a rotating body rotated once around the central axis.

[0086] The rate at which the radius defining the through cross section of the liquid pouring hole decreases toward the inside in the first direction may be constant.

[0087] The outer peripheral surface of the finishing member and the inner peripheral surface of the pouring port may be in contact with each other in a section where the finished cross section of the finishing member gradually decreases toward the inside in the first direction.

[0088] In a predetermined section inward in the first direction from the position where the outer peripheral surface of the finishing member and the inner peripheral surface of the pouring port meet, the rate at which the finishing cross-section of the finishing member decreases may be even greater than the rate at which the through cross-section of the pouring port decreases as one moves inward in the first direction.

[0089] In a predetermined section outward in the first direction from the position where the outer peripheral surface of the finishing member and the inner peripheral surface of the liquid inlet meet, the rate at which the finishing cross-section of the finishing member decreases as it moves inward in the first direction may be even smaller than the rate at which the through cross-section of the liquid inlet decreases.

[0090] As a result, in the section between the inside in the first direction and the outside in the first direction at the position where the outer surface of the finishing member and the inner surface of the pouring port contact, the outer surface of the finishing member and the inner surface of the pouring port are not pressed in the second direction, and no frictional force is required.

[0091] The position where the outer peripheral surface of the finishing member and the inner peripheral surface of the liquid pouring port come into contact may be located further inward in the first direction than the position where the finishing member has the largest finishing cross section.

[0092] This makes it possible for the finishing member to easily separate from the pouring port outward in the first direction when the sealing fixing material loses its fixing force.

[0093] The sealed section may be provided further outward in the first direction than a position where an outer circumferential surface of the finishing member and an inner circumferential surface of the pouring port come into contact with each other.

[0094] The finishing member may be made of a metal material.

[0095] The sealing fixing material may include solder that fills the space between the outer surface of the finishing member and the inner surface of the liquid inlet in the sealed section, with the outer surface of the finishing member in contact with the inner surface of the liquid inlet.

[0096] The finishing member may be a ball.

[0097] The electrode assembly may include a first electrode and a second electrode, and the tabs of the first electrode and the tabs of the second electrode may be disposed on opposite sides of the electrode assembly in an axial direction.

[0098] The tabs may be portions of the metal foils of the first and second electrodes that extend further outward in the axial direction from both axial ends of the electrode assembly.

[0099] The tab may be a notched tab.

[0100] The tabs may be folded radially.

[0101] This allows the bent tab portion to present a plane that is substantially perpendicular to the axial direction.

[0102] The tabs may be folded radially inward.

[0103] A first electrode terminal may be provided on a bottom portion of the can opposite the open end in the axial direction, the first electrode terminal being fixed to the bottom portion and electrically insulated from the bottom portion.

[0104] The bottom portion around the first electrode terminal may constitute a second electrode terminal 15, and the sidewall portion connected to the bottom portion may also constitute a second electrode terminal.

[0105] The first electrode of the electrode assembly may be connected to the first electrode terminal via a current collecting plate 31 joined to a tab of the first electrode.

[0106] This allows the first electrode terminal to have a first polarity.

[0107] The cap may include an electrode connection portion that is thermally bonded to a tab of the second electrode of the electrode assembly.

[0108] The thermal bonding can be performed before the liquid is poured.

[0109] The electrode connector may be recessed from a surface of the cap toward an inner side in an axial direction.

[0110] The electrode connecting portion may extend flatly in the radial direction.

[0111] The thermal bonding of the cap and the tab of the second electrode can be performed by any one of welding, brazing, and soldering.

[0112] The thermally bonded portion may be a weld formed by irradiating a laser beam onto the surface of the electrode connecting portion in a radial direction by scanning.

[0113] The liquid inlet may be provided in the center of the cap.

[0114] The electrode connecting portion may extend radially around the liquid injection port.

[0115] A plurality of the electrode connectors may be provided, each recessed into the inside of the can and extending in a radial direction.

[0116] The number of the electrode connectors may be four.

[0117] The side edges of the open end of the can and the edge of the cap can be thermally bonded.

[0118] The thermal joining of the can and the cap can be performed by any one of welding, brazing, and soldering.

[0119] Therefore, the cap, the sidewall connected to the cap, and the bottom connected to the sidewall can have a second polarity.

[0120] The thermal bonding can be performed before the liquid is poured.

[0121] The cap may include a receiving surface extending axially outward from the electrode connecting portion.

[0122] The height of the joint between the cap and the can may be lower than the height of the receiving surface and higher than the height of the electrode connecting portion, thereby protecting the joint, positioning the inlet lower than the receiving surface to protect the finish structure of the inlet, and enabling smooth venting.

[0123] One aspect of the present invention provides a method for manufacturing a battery cell to which the above-described sealing structure for the liquid filling port is applied.

[0124] The manufacturing method includes a can preparation step of preparing a can having a side wall portion, a bottom portion connected to one axial end portion of the side wall portion, and an open end portion provided at the other axial end portion of the side wall portion, and sealingly and insulatedly fixing a first electrode terminal to a center of the bottom portion.

[0125] The manufacturing method includes a step of preparing an electrode assembly including a first electrode and a second electrode, the first electrode having a tab and the second electrode having a tab disposed on both sides in an axial direction.

[0126] The manufacturing method includes a cap preparation step of preparing a cap provided with a liquid injection hole.

[0127] After the can preparing step and the electrode assembly preparing step, the manufacturing method includes a first electrode terminal connecting step of placing the electrode assembly in the can so that the tab of the first electrode faces the bottom of the can and connecting the tab of the first electrode to the first electrode terminal.

[0128] The manufacturing method includes, after the electrode assembly preparing step and the cap preparing step, a second electrode connecting step of connecting the cap to the tab of the second electrode.

[0129] The manufacturing method includes, after the connecting step of the first electrode terminal, a cap fixing step of fixing the cap to the can.

[0130] The manufacturing method includes a step of injecting an electrolyte into the can after the steps of connecting the first electrode terminal, connecting the second electrode, and fixing the cap.

[0131] The manufacturing method includes, after the pouring step and the plug preparation step, a pouring port finishing step in which the finishing member is inserted into the pouring port, and the space between the inner surface of the pouring port and the outer surface of the finishing member is sealed with a sealing fixative having a melting point lower than the melting point of the cap on which the pouring port is provided and the melting point of the finishing member, thereby sealing and fixing the finishing member within the pouring port.

[0132] According to this, the electrode assembly and the cap and the can and the cap can be thermally bonded before the electrolyte is poured, and the heat of the bonding can be prevented from affecting the electrolyte.

[0133] The finishing step of the liquid inlet can be performed by pushing the finishing member, the surface of which is coated with the sealing material, into the liquid inlet, and elastically compressing the sealing material between the outer peripheral surface of the finishing member and the inner peripheral surface of the liquid inlet.

[0134] The finishing step of the liquid inlet can be performed by inserting a finishing member into the liquid inlet, and soldering the space between the outer circumferential surface of the finishing member and the inner surface of the liquid inlet with a sealing fixing material while the outer circumferential surface of the finishing member is in line contact with the inner circumferential surface of the liquid inlet.

[0135] One aspect of the present invention provides a battery pack including the battery cell.

[0136] Another aspect of the present invention provides a vehicle equipped with the battery pack. [Effects of the Invention]

[0137] According to one aspect of the present invention, when finishing the pouring port, a sealing and fixing material is used that seals and fixes the finishing member to the finishing member, but loses its sealing and / or fixing force at a predetermined melting point, thereby allowing the electrolyte to be poured through the pouring port, and while seam welding of the cap is possible, the pouring port itself can function as a vent structure without the need for a separate vent structure.

[0138] Furthermore, according to one aspect of the present invention, the structure for fixing the cap to the can and the structure for fixing the cap to the electrode tab do not occupy space, so that the energy density of the battery cell can be increased.

[0139] According to one aspect of the present invention, since the circular tubular filling port is disposed so as to extend into the hollow portion of the winding core of the electrode assembly, the filling port and its finishing structure do not occupy the space in which the electrode assembly can be accommodated, thereby maximizing the internal volume of the can that can accommodate the electrode assembly, thereby increasing the energy density of the battery cell. Furthermore, since the outer periphery of the circular tube supports the separator surrounding the inner periphery of the hollow portion of the winding core of the electrode assembly, the separator surrounding the inner periphery of the hollow portion of the winding core of the electrode assembly is not damaged by the electrolyte during the filling process.

[0140] Furthermore, according to one aspect of the present invention, the air inside the can is smoothly discharged through the air hole during injection, and when the injection port is finished, this portion is also finished, so that the electrode assembly can be smoothly impregnated with the electrolyte.

[0141] According to one aspect of the present invention, a pressing force strong enough to cause elastic deformation of the inner circumferential surface of the pouring hole or the finishing member is not applied, so there is no risk of the cap being deformed or the internal electrode of the battery can being damaged.

[0142] According to one aspect of the present invention, high-temperature heat is not generated when finishing the filler hole, so that the heat applied while finishing the filler hole can be prevented from being transferred to the electrolyte or electrode assembly, thereby preventing the performance of the battery from being affected.

[0143] According to one aspect of the present invention, when finishing a pouring port, a finishing member with high strength and rigidity is used to finish most of the through cross section of the pouring port, and a sealing fixing material with a low melting point and which acts as a vent is interposed between the inner surface of the pouring port and the finishing member, thereby fixing the finishing member to the pouring port.

[0144] Thus, one aspect of the present invention has the advantage that a sealing material is interposed in the space between a finishing member, which has sufficient strength and rigidity, and the inner surface of the pouring port, preventing the sealing material from being exposed to the outside and protecting the sealing material, which has weak strength and rigidity, from being damaged by external impact, and that the sealing material, which has weak strength and rigidity, is reinforced by the inner surface of the pouring port and the finishing member, thereby ensuring that both the sealing function of the pouring port and the vent function are reliably performed.

[0145] The above-mentioned effects and specific effects of the present invention will be described in conjunction with the following description of the preferred embodiment of the invention. [Brief explanation of the drawings]

[0146] [Figure 1] 1A and 1B are diagrams showing a conventional method for finishing a cap and an electrolyte injection port of a battery can. [Figure 2] 1A and 1B are diagrams showing a conventional method for finishing a cap and an electrolyte injection port of a battery can. [Figure 3] 1A and 1B are diagrams showing the sealing structure and vent structure of a liquid inlet in a first embodiment according to the present invention. [Figure 4] 1A and 1B are diagrams showing the sealing structure and vent structure of a liquid inlet in a first embodiment according to the present invention. [Figure 5] 1A and 1B are diagrams showing the sealing structure and vent structure of a liquid inlet in a first embodiment according to the present invention. [Figure 6] 1A and 1B are diagrams showing the sealing structure and vent structure of a liquid inlet in a first embodiment according to the present invention. [Figure 7] 1A and 1B are diagrams showing the sealing structure and vent structure of a liquid inlet in a first embodiment according to the present invention. [Figure 8]1A and 1B are diagrams showing the sealing structure and vent structure of a liquid inlet in a first embodiment according to the present invention. [Figure 9] 10A and 10B are diagrams showing the sealing structure and vent structure of the liquid inlet of a second embodiment according to the present invention. [Figure 10] 10A and 10B are diagrams showing the sealing structure and vent structure of the liquid inlet of a second embodiment according to the present invention. [Figure 11] 10A and 10B are diagrams showing the sealing structure and vent structure of the liquid inlet of a second embodiment according to the present invention. [Figure 12] 10A and 10B are diagrams showing the sealing structure and vent structure of the liquid inlet of a second embodiment according to the present invention. [Figure 13] 10A and 10B are diagrams showing the sealing structure and vent structure of the liquid inlet of a second embodiment according to the present invention. [Figure 14] 10A and 10B are diagrams showing the sealing structure and vent structure of the liquid inlet of a second embodiment according to the present invention. [Figure 15] 10A and 10B are diagrams showing the sealing structure and vent structure of the liquid inlet of a second embodiment according to the present invention. [Figure 16] 10A and 10B are diagrams showing the sealing structure and vent structure of the liquid inlet of a second embodiment according to the present invention. [Figure 17] FIG. 10 is a perspective view of a battery cell according to a third embodiment. [Figure 18] 1 is a perspective view showing a state before a first electrode, a second electrode, and a separator are stacked to manufacture an electrode assembly to be housed in a battery can. FIG. [Figure 19] 10 is a perspective view showing a state after laminating a first electrode, a second electrode, and a separator to manufacture an electrode assembly to be housed in a battery can. FIG. [Figure 20] FIG. 20 is a plan view of the stacked state of FIG. [Figure 21] FIG. 21 is a perspective view of an electrode assembly manufactured by winding the laminate of FIGS. 19 and 20 into a jelly roll. [Figure 22] 21 is a side view of an electrode assembly manufactured by winding the laminate of FIGS. 19 and 20 into a jelly roll. FIG. [Figure 23] 10 is a perspective view showing a state in which a current collector plate is joined to the upper part of an electrode assembly and a current collector plate is not joined to the lower part of the electrode assembly. FIG. [Figure 24] 10 is a perspective view showing a state in which a current collector plate is joined to the upper part of an electrode assembly and a current collector plate is not joined to the lower part of the electrode assembly. FIG. [Figure 25] 25 is a multi-faceted view showing the process of housing the electrode assembly of FIG. 23 and FIG. 24 in a battery can. [Figure 26] 5A to 5C are cross-sectional views showing a process of welding the first electrode terminal and the current collector plate. [Figure 27] 10 is a cross-sectional view showing a process of covering the open end of the battery can with a cap, joining the electrode connecting portion of the cap to the tab of the second electrode of the electrode assembly, and joining the edge of the cap around the open end of the battery can. [Figure 28] 10A and 10B are diagrams illustrating a process of injecting an electrolyte solution through a liquid injection hole and sealing the liquid injection hole. [Figure 29] 10A and 10B are diagrams illustrating a process of injecting an electrolyte solution through a liquid injection hole and sealing the liquid injection hole. [Figure 30] FIG. 10 is a top perspective view of a cap according to a fourth embodiment. [Figure 31] FIG. 10 is a perspective view of the lower part of the cap of the fourth embodiment. [Figure 32] FIG. 10 is a plan view of a cap according to a fourth embodiment. [Figure 33] FIG. 33 is a cross-sectional view of the relevant portion of FIG. 32. [Figure 34] FIG. 33 is a cross-sectional view of the relevant portion of FIG. 32. [Figure 35] 10 is a perspective view showing a state in which a cap is joined to a lower portion of an electrode assembly. FIG. [Figure 36] 10A to 10C are diagrams showing the steps of a fifth embodiment of a method for manufacturing a battery cell to which a finishing structure for a liquid filling port is applied. [Figure 37] 10A to 10C are diagrams showing the steps of a sixth embodiment of a method for manufacturing a battery cell to which a finishing structure for a liquid filling port is applied. [Figure 38] 1 is a diagram showing a battery pack to which a battery cell according to an embodiment of the present invention is applied; [Figure 39] 1 is a diagram showing an automobile equipped with a battery pack to which a battery cell according to an embodiment of the present invention is applied; DETAILED DESCRIPTION OF THE INVENTION

[0147] In the following, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0148] The present invention is not limited to the embodiments disclosed below, but may be embodied in various different forms and may be modified in various ways. However, these embodiments are provided to fully disclose the present invention and to fully convey the scope of the invention to those skilled in the art. Therefore, the present invention is not limited to the embodiments disclosed below, and should be understood to include all modifications, equivalents, and alternatives within the technical spirit and scope of the present invention, including the substitution or addition of the structure of any embodiment with the structure of another embodiment.

[0149] The accompanying drawings are intended to facilitate understanding of the embodiments disclosed in this specification, and should not be construed as limiting the technical ideas disclosed in this specification, but should be understood to include any modifications, equivalents, or alternatives that fall within the spirit and technical scope of the present invention. The components in the drawings may be exaggerated in size or thickness for ease of understanding, but this should not be interpreted as limiting the scope of protection of the present invention.

[0150] The terms used in this specification are merely used to describe particular embodiments or examples and are not intended to limit the present invention. Furthermore, singular terms include plural terms unless the context clearly dictates otherwise. Terms such as "comprises," "consists," and the like in the specification are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification. In other words, terms such as "comprises," "consists," and the like in the specification should not be understood to preclude the presence or possibility of adding one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0151] Although terms including ordinal numbers, such as first, second, etc., may be used to describe various components, the components are not limited by these terms. These terms are used only to distinguish one component from another. Thus, unless otherwise specified, a first component may also be a second component.

[0152] When a component is referred to as being "coupled" or "contacted" with another component, it should be understood that the component may be directly coupled to or in contact with the other component, but that there may be other components between them. On the other hand, when a component is referred to as being "directly coupled" or "in direct contact" with another component, it should be understood that there are no other components between them.

[0153] When a component is referred to as being "on top of" or "under" another component, it should be understood that it may be located not only directly on top of the other component, but that there may be other components in between.

[0154] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms commonly used and similar to dictionary definitions should be interpreted to have a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0155] Throughout the specification, unless otherwise specified, "A and / or B" means A, B or A and B, and "C to D" means C or more and D or less.

[0156] In describing the embodiments, the axial direction refers to the direction in which the axis that forms the winding center of the jelly roll-type electrode assembly extends, the radial direction refers to the direction toward (centripetal) or away (centrifugal) from the axis, and the circumferential direction refers to the direction surrounding the axis.

[0157] [First Example] A sealing structure for a liquid pouring port according to a first embodiment of the present invention will be described below with reference to FIGS.

[0158] The liquid pouring port 42 of the embodiment is provided in the center of the cap 40 .

[0159] The inner surface of the cap 40 is joined and electrically connected to the tab of the second electrode of the electrode assembly 20 housed inside the can 10 of the battery cell, and the edge of the cap 40 is joined and electrically connected to the side edge of the open end of the can 10.

[0160] In this state, the electrolyte is poured into the can 10 through the pouring port 42 of the cap 40. After the pouring of the electrolyte is completed, a finishing member 50 is inserted into the pouring port 42, and the finishing member 50 is sealed and fixed to the inner peripheral surface of the pouring port 42 with a sealing fixing member 52.

[0161] The cap 40 can be manufactured by pressing a metal plate material, and the liquid pouring hole 42 can be manufactured by drawing the center of the cap 40 in a first direction.

[0162] The first direction may be a direction that crosses the exterior and interior of the battery cell.

[0163] The liquid inlet 42 can be defined by a circular pipe 48 extending in a first direction in the center of the cap 40. That is, the inner circumferential surface of the circular pipe 48 defines the liquid inlet 42. Hereinafter, the inner circumferential surface of the liquid inlet 42 should be understood to refer to the inner circumferential surface of the circular pipe 48.

[0164] The liquid inlet 42 has a through section extending in the first direction and has a through cross section defined by the intersection of an imaginary plane (T) extending in a second direction intersecting the first direction and the inner circumferential surface of the liquid inlet 42.

[0165] The first direction may correspond to the axial direction of the electrode assembly 20 and the can 10. The second direction may correspond to the radial direction of the electrode assembly and the can 10. The first and second directions may be perpendicular to each other.

[0166] The through cross section of the liquid pouring port 42 defined by the inner circumferential surface of the circular pipe 48 may be circular.

[0167] The inner peripheral surface of the circular tube 48 extending in the axial direction may have a substantially constant through cross section along the axial direction. Strictly speaking, due to the characteristics of the process, the circular tube 48 may have a shape in which the radius gradually decreases as it goes inward in the first direction during the drawing process, but this can be understood as having a substantially constant through cross section when only a minimum tilt is applied to remove the mold after processing.

[0168] The portion where the circular tube 48 is connected to the cap 40 may include a guide surface 481, which is a section (R5→R2) whose radius gradually decreases in a rounded shape as it goes inward in the first direction. These rounded shapes are naturally formed during the drawing process for forming the circular tube 48, and can function as a guide surface that guides the insertion of the finishing member 50 into the pouring hole 42.

[0169] The extension length of the circular pipe 48 in the first direction defines the through-section (T) of the pouring port 42. The through-section (T) of the pouring port 42 can approximately correspond to the diameter of the finishing member 50 or the synthetic resin layer 54. This prevents the finishing member 50 from significantly protruding inward or outward from the pouring port 42 in the first direction when the finishing member 50 is sealed and fixed to the pouring port 42.

[0170] Optionally, the inner end of the circular tube 48 in the first direction may extend inward in the second direction like an inward flange and have a reduced radius (R1) compared to the circular tube 48.

[0171] The inlet 42 may have a shape in which the diameter is substantially constant overall along the first direction and the through cross section is substantially constant, and the outer end in the first direction may have the shape of a guide surface 481, and the inner end in the first direction may have the shape of an inward flange.

[0172] The radius (R2) of the liquid inlet 42 is smaller than the radius of the hollow portion 29 of the core of the electrode assembly 20.

[0173] The substantial radius (R2) of the liquid pouring hole 42 may be 1 mm or more and 10 mm or less. Preferably, the radius (R2) may be 2 mm or more and 8 mm or less.

[0174] The finishing member 50 may be a ball 50 made of a metal material, and the sealing fixing material 52 may be a synthetic resin coated on the surface of the metal ball 50 to a predetermined thickness.

[0175] The elastic modulus of the material of the sealing fastener 52 is smaller than the elastic modulus of the material of the ball 50 and is smaller than the elastic modulus of the material of the circular tube 48 .

[0176] The elastic modulus of the material of the sealing fastener 52 may be 0.2 times or less than the elastic modulus of the ball 50 and the elastic modulus of the circular tube 48 .

[0177] The sealing fixing material 52 may be coated on the entire surface of the metal ball 50. As a result, the finishing member 50 having the synthetic resin layer 54 coated on its surface has no directionality and is easy to manufacture and handle.

[0178] If the cross section of the finishing member 50 defined by a plane perpendicular to the first direction is defined as the finishing cross section, it can be seen that all of the finishing cross sections of the ball-shaped finishing member 50 are circular. It can also be seen that the finishing member 50 has a maximum finishing cross section with a radius (R3) at the center in the first direction, and the radius gradually decreases as it moves away from the center in the first direction toward the inside or outside in the first direction, and therefore the finishing cross section also gradually decreases.

[0179] The sealing fixture 52 may have a sealing cross section defined by the intersection of an imaginary plane extending in the second direction and the outer circumferential surface of the sealing fixture 52. The sealing fixture 52 is also laminated on the surface of the metal ball 50 at a predetermined thickness, and therefore has a sealing cross section similar to the finished cross section of the finishing member 50 described above, but is larger than the finished cross section by an amount corresponding to the thickness.

[0180] In the following, when explaining the through cross section, the finishing cross section, and the sealing cross section, since they are all circular, the sizes of the cross sections will be compared based on their radii.

[0181] The laminate thickness (R4-R3) of the sealing fastener 52 may be approximately 0.1 mm or more and 5.0 mm or less. If the thickness is less than 0.1 mm, the sealing fastener 52 may be damaged during the process of pressing the finishing member 50, and even if it is not damaged, it is difficult to ensure sealing force. If the thickness is 5.0 mm or more, in an environment where the diameter of the pouring hole 42 is limited, the metal ball 50 has to be made small, and it is difficult for the metal ball 50 to function as a framework to support the overall shape of the sealing fastener 52.

[0182] The radius (see R3) of the maximum finished cross section of the finishing member 50 is the same as or smaller than the radius (R2) of the through cross section of the liquid inlet 42. In the embodiment, the maximum finished cross section of the finishing member 50 is illustrated as being slightly smaller than the through cross section of the liquid inlet 42. That is, the difference therebetween (R2-R3) may be approximately greater than 0 mm and equal to or less than 2.0 mm.

[0183] The maximum finished cross section (see R4) of the sealing fastener 52 is larger than the through cross section (R2) of the pouring hole 42. The thickness (R4-R3) of the sealing fastener 52 may be approximately 1.1 to 5 times the difference (R-R3) between the inner diameter (R2) of the pouring hole 42 and the radius (R3) of the ball 50.

[0184] When the metal ball 50 coated with the synthetic resin layer 54 is pressed into the liquid inlet 42, the synthetic resin layer 54 compresses, and the metal ball 50 is pressed into the liquid inlet 42. At this time, since the diameter of the metal ball 50 is not larger than the inner diameter of the liquid inlet 42, a large pressing force is not required, and the metal ball 50 and the circular tube 48 are deformed less than the synthetic resin layer 54.

[0185] With the finishing member 50 inserted into the pouring port 42, at least a portion of the finishing member 50 in the first direction is disposed within the through-section (T) of the pouring port 42. Preferably, the center of the ball 50 may be disposed at the center of the circular tube 48 in the longitudinal direction.

[0186] With the finishing member 50 inserted into the pouring port 42, the sealing fixing material 52 is interposed between the inner peripheral surface of the pouring port 42 and the outer peripheral surface of the finishing member 50 in the second direction.

[0187] The sealing fixing material 52 blocks the space between the inner surface of the pouring port 42 and the outer surface of the finishing member 50 in a sealing section (S), which is at least a portion of the section in the first direction, and fixes the finishing member 50 within the pouring port 42.

[0188] The sealed section (S) is preferably disposed approximately in the center of the through section (T).

[0189] The sealing cross section of the sealing fastener 52 disposed in the sealed section (S) is larger than the through cross section of the filling hole 42 in the sealed section. As a result, the sealing fastener 52 is compressed inward in the second direction by the inner circumferential surface of the filling hole 42, and contracts to correspond to the through cross section within the sealed section.

[0190] The point (A1) where the finishing cross section of the finishing member 50 is maximum is located approximately in the middle of the sealed section (S).

[0191] The shape of the sealing member 52 corresponds to the surface of a sphere, so that the sealing cross section gradually decreases inward in the first direction from the sealing section (S). As a result, when the finishing piece 50 is pressed into the pouring hole 42, the sealing member 52 can be smoothly inserted into the pouring hole 42, and as the finishing piece 50 is pressed into the pouring hole 42, the sealing member 52 can naturally elastically compress in the second direction.

[0192] The sealing fixture 52 entirely surrounds the metal ball 50, so that the inner end of the sealing fixture 52 in the first direction covers the finishing member 50 in the first direction. This prevents the sealing fixture 52 from being detached from the surface of the finishing member 50 due to the tensile force in the first direction when the finishing member 50 is pressed in.

[0193] Since the finishing member 50 is a metal ball 50, the finishing cross section gradually becomes smaller inward in the first direction from the sealing section inward in the first direction. This ensures the thickness of the sealing fastener 52 laminated on the surface of the finishing member 50 in that section, and prevents the sealing fastener 52 from breaking due to the tensile force in the first direction when the finishing member 50 is pressed in.

[0194] The sealing fixing material 52 has a melting point lower than the melting point of the can 10 or the cap 40 on which the pouring hole 42 is formed and the melting point of the finishing member 50. The melting point of the synthetic resin layer 54 may be 100°C or higher and 300°C or lower.

[0195] 8, if thermal runaway occurs in the battery cell, the synthetic resin layer 54 melts and loses its sealing force and its fixing force to the ball 50. As a result, venting can be smoothly performed through the space between the ball 50 and the inner circumferential surface of the filling hole 42.

[0196] The minimum size (R1) of the through cross section of the inlet 42 is located at the inner end (A2) in the first direction of the inlet 42, and is smaller than the maximum size (R3) of the finishing cross section of the finishing member 50.

[0197] The first direction position (A1) where the penetration cross section has the smallest size is located further inward than the sealing section (S), so that even if the sealing fastener 52 melts and loses its fastening force to the finishing member 50, there is no risk of the finishing member 50 falling into the can 10 through the pouring hole 42.

[0198] Meanwhile, the circular tube 48 defining the liquid inlet 42 may extend in the axial direction into the hollow core portion 29 of the electrode assembly 20. The upper end of the separator wound around the inner circumferential surface of the hollow core portion of the electrode assembly 20 is positioned further above the circular tube 48.

[0199] Therefore, the flow of the electrolyte that occurs when the electrolyte is injected into the injection port 42 can be prevented from striking the upper end of the separation membrane on the inner circumferential surface of the core hollow portion 29, which would cause the separation membrane to become detached or deformed.

[0200] Furthermore, since there is no need to secure additional space for adding a fill port and its finishing structure, the energy density of the battery cell is increased and the fill port and vent structure are added.

[0201] Furthermore, since the can 10, the cap 40, and the electrode tabs are joined by high temperature welding or the like before the electrolyte is poured, the assembly process of the cap 40 does not adversely affect the electrolyte.

[0202] [Second Example] A sealing structure for a liquid filling port according to a second embodiment of the present invention will be described below with reference to FIGS. 9 to 16. In describing the second embodiment, differences from the first embodiment will be mainly described. Therefore, it goes without saying that content not described in any of the embodiments can be understood from the descriptions of the other embodiments. Furthermore, it should be understood that the configuration of any of the embodiments can be applied to the other embodiments, and that substitutions, deletions, and additions can be made between the configurations of the different embodiments.

[0203] The liquid filling port 42 can be defined by a circular tube 48 extending in a first direction in the center of the cap 40. In the first embodiment, the liquid filling port 42 has a shape having a through cross section that is substantially constant in the first direction. In contrast, the liquid filling port 42 of the second embodiment has a shape in which the through area gradually decreases toward the inside in the first direction. That is, the circular tube 48 defining the liquid filling port 42 may be a tapered circular tube as shown in the figure. The taper angle may be inclined at an angle of about 1 to 5 degrees with respect to the first direction. That is, the rate at which the radius defining the through cross section of the liquid filling port 42 decreases toward the inside in the first direction may be constant.

[0204] As a result, the radius of the through-section of the inlet 42 decreases from R5 to R2 along the rounded inner circumferential surface of the guide surface 481, and then decreases steadily toward the inside in the first direction, down to R1.

[0205] The finishing member 50 may be a spherical metal ball 50. The radius (R3) of the finishing member 50 may be smaller than the maximum radius (R2) of the tapered section of the pouring hole 42 and larger than the minimum radius (R1). The radius (R3) of the finishing member 50 may be determined as a dimension that allows the finishing member 50 to be positioned close to the center of the through section (T) of the pouring hole 42 when the finishing member 50 is inserted into the pouring hole 42.

[0206] Unlike the first embodiment, the sealing fixture 52 of the second embodiment can be provided separately from the finishing member 50. Furthermore, when the finishing member 50 is inserted into the liquid inlet 42, the sealing fixture 52 of the second embodiment fills the space between the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42, thereby fixing the finishing member 50 within the liquid inlet 42 and sealing the space between the finishing member 50 and the liquid inlet 42.

[0207] The sealing fixing material 52 may be solder 56 having a melting point lower than that of the cap 40 and the ball 50. The solder 56 may be lead-free solder. The melting point of the solder 56 may be between 300 degrees Celsius and 500 degrees Celsius.

[0208] As a result, when the sealing fixing material 52 is melted and fills the space between the outer surface of the finishing member 50 and the inner surface of the pouring port 42, the inner surface of the pouring port 42 and the finishing member 50 can remain in a solid state.

[0209] According to the sealing structure for the pouring port of the second embodiment, first, as shown in Fig. 12, the finishing member 50 is inserted into the pouring port 42. As a result, the outer peripheral surface of the finishing member 50 comes into contact with the inner peripheral surface of the pouring port 42.

[0210] The finishing member 50 is not pushed strongly into the liquid pouring port 42. That is, the finishing member 50 is not inserted strongly or forcibly into the liquid pouring port 42. The finishing member 50 is inserted into the liquid pouring port 42 with a light load applied. For example, the load may be a force equivalent to the force of gravity or a force slightly greater than that.

[0211] In this way, when the finishing member 50 is inserted into the pouring port 42, the finishing member 50 is inserted into the pouring port 42 until the finishing member 50 contacts the inner peripheral surface of the pouring port 42. When the finishing member 50 is inserted into the pouring port 42 with a light pressure, the finishing member 50 and the inner peripheral surface of the pouring port 42 do not substantially elastically deform. As a result, the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the pouring port 42 are in substantially line contact in the circumferential direction.

[0212] This can be distinguished from the forced pushing method, in which the finishing member 50 is pushed firmly into the pouring port 42, causing elastic deformation of at least one of the inner surfaces of the finishing member 50 and the pouring port 42, resulting in surface contact between the finishing member 50 and the pouring port 42 in the circumferential direction.

[0213] The circular tube 48 has a straight tapered shape, and the finishing member 50 is spherical, so that the outer surface of the finishing member 50 and the inner surface of the inlet 42 meet in a section where the through cross section of the inlet 42 gradually decreases as it goes inward in the first direction.

[0214] That is, the inclination of the inner surface of the liquid inlet 42 may be constant in a predetermined section inward in the first direction from the position where the outer surface of the finishing member 50 and the inner surface of the liquid inlet 42 meet and in a predetermined section outward in the first direction.

[0215] This ensures that a space for venting can be secured between the finishing member 50 and the inner peripheral surface of the pouring hole 42 when the sealing and fixing material 52 loses its sealing and fixing force.

[0216] The finishing member 50 is a spherical metal ball 50, and the circular tube 48 has a tapered shape at a constant inclination. Therefore, in a predetermined section inward in the first direction from the position where the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the pouring port 42 meet, the rate at which the finishing cross-section of the finishing member 50 decreases as it goes inward in the first direction may be even greater than the rate at which the through cross-section of the pouring port 42 decreases.

[0217] Similarly, in a predetermined section outward in the first direction from the position where the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42 meet, the rate at which the finishing cross-section of the finishing member 50 decreases may be even smaller than the rate at which the through cross-section of the liquid inlet 42 decreases as one moves inward in the first direction.

[0218] As a result, in the inner and outer sections in the first direction at the position where the outer surface of the finishing member 50 and the inner surface of the liquid inlet 42 contact, the outer surface of the finishing member 50 and the inner surface of the liquid inlet 42 are not pressed against each other in the second direction, and no frictional force is required.

[0219] Referring to Figure 14, the position (A3) where the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42 contact is located further inward in the first direction than the position (A1) where the finishing member 50 has the largest finishing cross section.

[0220] As a result, when a sealing fixing material 52, which will be described later, loses its fixing force, the finishing member 50 is likely to come off from the liquid pouring hole 42 to the outside in the first direction.

[0221] As described above, when the finishing member 50 is seated within the pouring port 42, the sealing fixing material 52 can be fused between the inner surface of the pouring port 42 and the outer surface of the finishing member 50, outside the contact position (A3) between the inner surfaces of the finishing member 50 and the pouring port 42 in the first direction.

[0222] As a result, the sealed section (S) may be provided further outward in the first direction than the position (A3) where the outer circumferential surface of the finishing member 50 and the inner circumferential surface of the pouring port 42 come into contact.

[0223] When thermal runaway occurs in the battery cell, the solder 56 melts, and the solder 56 cannot withstand the internal pressure of the can 10, causing the high-pressure gas inside the can to be released to the outside through the liquid inlet 42, as shown in FIG.

[0224] The sealing structure of the liquid inlet of the second embodiment differs from that of the first embodiment in that an air hole 483 is provided in the circular tube 48.

[0225] The inner end of the circular tube 48 in the first direction extends in the axial direction so as to be inserted into the core hollow portion 29 of the electrode assembly 20. In this case, the inner end of the circular tube 48 in the first direction may be disposed so as to extend further inward (h1) in the axial direction than a height (h2) at which the electrode assembly 20 must be impregnated with the electrolyte.

[0226] In this state, when the electrolyte is poured through the pouring port 42, the electrolyte fills the can 10 from the bottom 12. When the electrolyte fills up to the height (h1) of the inner end of the circular tube 48 in the first direction, the space from the height (h1) to the bottom surface of the cap 40 can form an air pocket space in which air is trapped.

[0227] According to the embodiment, the circular tube 48 is provided with an air hole 483. The air hole 483 may be located at a height (h2) corresponding to or above the height at which the electrolyte must be impregnated in the electrode assembly 20. In this way, when the electrolyte is being filled, air in the air pockets is discharged through the air hole 483, and the electrolyte is sufficiently filled up to the upper end of the electrode assembly 20, allowing the electrolyte to be smoothly impregnated up to the required height (h2).

[0228] The air hole 483 is disposed in the sealed section (S). Thus, after pouring, the air hole 483 does not need to be blocked separately; it is also blocked during the process of finishing the pouring hole with the sealing fixing material 52. That is, after pouring is completed and the ball 50 is inserted into the pouring hole 42, the air hole 483 is sealed by the solder 56 that seals the gap between the inner circumferential surface of the pouring hole 42 and the surface of the ball 50, and therefore, it can be processed together with the finishing of the pouring hole without a separate process.

[0229] It goes without saying that air hole 483 exemplified in the second embodiment can also be applied to the seal structure of the liquid filling port of the first embodiment. That is, in the first embodiment, if air hole 483 is provided in the sealed section (S) where synthetic resin layer 54 is pressed, air hole 483 can also be blocked in the process of finishing the liquid filling port with sealing fixing material 52, as in the second embodiment.

[0230] [Battery cell assembly] Hereinafter, a method for manufacturing a battery cell to which the above-described sealing structure for the liquid filling port is applied, and the structure of the battery cell will be described as a third embodiment of the present invention with reference to FIGS.

[0231] FIG. 17 discloses a cylindrical battery cell.

[0232] The battery cell of the embodiment may be, for example, a cylindrical battery cell having a form factor ratio (defined as the diameter of a cylindrical battery cell divided by its height, i.e., the ratio of the diameter (Φ) to the height (H)) greater than approximately 0.4.

[0233] Here, the form factor refers to values ​​indicating the diameter and height of a cylindrical battery cell. Cylindrical battery cells applicable to pressure testers may be, for example, 46110 cells, 48750 cells, 48110 cells, 48800 cells, or 46800 cells. In the form factor number, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the final 0 indicates that the cross section of the cell is circular.

[0234] The battery cell applied to the pressure tester may be a cylindrical battery cell that is approximately cylindrical, has a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0235] A battery cell according to another embodiment may be a cylindrical battery cell that is approximately cylindrical, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0236] In yet another embodiment, the battery cell may be a cylindrical battery cell that is approximately cylindrical, has a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0237] In yet another embodiment, the battery cell may be a cylindrical battery cell that is approximately cylindrical, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0238] In yet another embodiment, the battery cell may be a cylindrical battery cell that is approximately cylindrical, with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0239] It goes without saying that a pressure tester according to one embodiment of the present invention can be applied to battery cells with a form factor ratio of approximately 0.4 or less, such as 18650 cells and 21700 cells. For an 18650 cell, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. For a 21700 cell, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0240] The battery can 10 includes a cylindrical side wall 11 and a bottom 12 connected to one axial end of the side wall 11. Here, the term "bottom" is used because the bottom 12 is placed on the floor in the process of assembling the battery cell, with the open end of the battery can 10 facing upward as shown in FIGS. 25 to 29. It should be understood that the bottom 12 may be located at the top together with the first electrode terminal 13 as shown in FIG. 17 in the process of actually using the battery cell.

[0241] The bottom 12 and the side wall 11 of the battery can 10 may be integral. For example, the battery can 10 may be manufactured by drawing a steel or aluminum sheet material. The opposite end of the side wall 11, which is not connected to the bottom 12, may form an open end that is open in the axial direction.

[0242] A hole may be formed in the center of the bottom 12, and a first electrode terminal 13 may be inserted into the hole for coupling. The first electrode terminal 13 may be riveted to the bottom 12 with a 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 electrolyte, and electrically insulate the first electrode terminal 13 from the bottom 12.

[0243] However, the method of connecting the first electrode terminal 13 and the bottom 12 is not limited thereto. For example, as long as the gap between the first electrode terminal 13 and the bottom 12 can be sealed and the first electrode terminal 13 and the bottom 12 can be electrically insulated, various other fixing methods, such as a bolt and nut connection method, a glass sill method, and a thermal bonding method of a PP-MAH insulating gasket using an insulating film such as PP (polypropylene) as a substrate, may also be applied.

[0244] In the embodiment, the first electrode terminal 13 may have a first polarity, and the battery can 10 may have a second polarity, so that the bottom 12 of the battery can 10 and the side wall 11 connected thereto may both have the second polarity.

[0245] In this case, the first electrode terminal 13 and the second electrode terminal 15 may both be disposed at one end of the battery can 10 in the axial direction. Accordingly, in the battery can 10, the bus bar connected to the first electrode terminal 13 and the bus bar connected to the second electrode terminal 15 may both be located at one end of the battery can 10 in the axial direction, i.e., at the top.

[0246] In one example, the first electrode terminal 13 may be a positive terminal and the second electrode terminal 15 may be a negative terminal, or vice versa.

[0247] An electrode assembly 20 is accommodated within the battery can 10. The electrode assembly 20 is manufactured by preparing a first electrode 21, a second electrode 22, and a separator 28, each having a predetermined width and extending in the longitudinal direction, as shown in Fig. 18, stacking the first electrode 21, the separator 28, the second electrode 22, and the separator 28 in this order, as shown in Figs. 19 and 20, and then winding the stack around a core shaft to form a jelly roll.

[0248] The first electrode 21 may be a positive electrode and the second electrode 22 may be a negative electrode, or vice versa.

[0249] The first electrode 21 and the second electrode 22 are fabricated in the form of sheets. The electrode sheets are fabricated by coating an active material layer 24 on the surface of a metal foil 23. The electrode sheets have two coated regions where the active material layer 24 is coated and an uncoated region 26 where the active material layer 24 is not coated. The positive electrode sheet has the uncoated region 26 on one side in the width direction, and the negative electrode sheet has the uncoated region 26 on the other side in the width direction.

[0250] The blank area 26 is exposed or protrudes in the width direction of the laminate, and the blank area 26 itself serves as an electrode tab.

[0251] Notches can be formed at predetermined intervals in the plain portion 26 to form flag-shaped notched tabs 27.

[0252] In the embodiment, the notched tab 27 is shaped like an equilateral trapezoid, but may have various other shapes such as a semicircle, an inverse ellipse, a triangle, a rectangle, a parallelogram, and the like.

[0253] In the embodiment, the notched tabs 27 arranged along the length direction have the same width. However, the width of the notched tabs may be gradually or stepwise increased from the core side to the outer periphery side.

[0254] In the embodiment, the height of the notched tabs 27 increases stepwise from the core side to the outer periphery side, but the height of the notched tabs may be constant or may decrease gradually.

[0255] In the embodiment, a structure is shown in which the notched tabs 27 are omitted from a predetermined section of the centripetal end and a predetermined section of the distal end of the non-coated portion 26. However, it goes without saying that the notched tabs at the centripetal end of the non-coated portion do not have to be omitted, and the notched tabs at the distal end of the non-coated portion do not have to be omitted.

[0256] In the jellyroll-type electrode assembly 20, the notched tabs 27 may be flattened by bending them radially. The notched tabs 27 may be bent radially inward or outward. In an embodiment, as shown in Figures 21 and 22, the notched tabs 27 may be bent radially inward.

[0257] The notched tabs 27 may be bent one by one during the process of winding the laminate to form the jelly roll type electrode assembly 20. Alternatively, the notched tabs 27 may be bent all at once after winding the laminate to form the jelly roll type electrode assembly.

[0258] In this way, the notched tabs 27 of the first electrode 21 and the notched tabs 27 of the second electrode 22, which are folded radially and overlapped, can provide planes that are substantially perpendicular to the axial direction at both axial ends of the electrode assembly 20, as shown in Figure 22.

[0259] As shown in FIG. 23, a first current collector plate 31 may be bonded to a substantially flat surface formed by bending the notched tabs 27 exposed at both axial ends of the electrode assembly 20.

[0260] The current collector plate 31 can be made by stamping, trimming, piercing and bending a metal sheet.

[0261] 23, the current collecting plate 31 includes terminal connecting portions 32 extending radially from the center, ring portions 33 connecting the distal edges of the terminal connecting portions 32 in the circumferential direction, and an electrode connecting portion 34 extending centripetally from the ring portions 33 but not connected to the terminal connecting portions 32. The center portion of the terminal connecting portion 32 covers at least a portion of the hollow portion of the winding core of the electrode assembly 20.

[0262] Before the electrode assembly 20 is placed in the battery can 10, the electrode connector 34 is joined to the notched tab 27 of the first electrode 21 of the electrode assembly 20 by a method such as laser welding.

[0263] Of course, in the case of a battery cell having a different structure, unlike the embodiment, for example, the notched tab 27 of the first electrode 21 or the current collector plate 31 can be electrically connected to the bottom 12 of the battery can 10 by joining it by a method such as welding. That is, it should be understood that the third embodiment is an example of a battery cell to which the above-described sealing structure of the filler hole can be applied. That is, it is clear that the sealing structure of the filler hole disclosed above is not a technology that can be applied only to the battery cell structure disclosed in the third embodiment.

[0264] 24, the current collecting plate does not have to be connected to the notched tab 27 of the second electrode 22 of the electrode assembly 20. It may be electrically connected to the cap 40 (described later) by directly joining the notched tab 27 to the cap 40 by welding or the like.

[0265] 25 and 26, the electrode assembly 20 is housed in the battery can 10 with the current collector 31 aligned toward the bottom 12 of the battery can 10. At this time, an insulator 19 is interposed between the current collector 31 and the bottom 12 of the battery can 10 to electrically insulate the current collector 31 from the bottom 12.

[0266] 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 resistance welding, ultrasonic welding, laser welding, or the like. A welding device for welding the current collector plate 31 to the first electrode terminal 13 may be positioned from the other axial end of the electrode assembly 20, through the hollow portion of the core of the electrode assembly 20, and approach the rear surface of the center of the terminal connection portion 32 of the current collector plate 31 to perform welding. Of course, the current collector plate 31 and the first electrode terminal 13 may also be joined by brazing or soldering.

[0267] Referring to FIG. 27, the notched tab 27 of the second electrode 22 may directly contact the cap 40 covering the open end of the battery can 10 when the electrode assembly 20 is housed in the battery can 10 and the first electrode 21 is connected to the first electrode terminal 13.

[0268] With the cap 40 tightly attached to the notched tab 27, a laser beam is irradiated onto the surface of the cap 40 in a scanning manner along the radial direction, as shown in Fig. 27, to form a weld (W) extending in the radial direction. Of course, the laser beam is not irradiated onto the section of the scanning path where the injection hole is provided.

[0269] As a result, the second electrode 22 is electrically connected through the welded portion (W) between the notched tab 27 and the cap 40. Of course, the notched tab 27 and the cap 40 can also be joined by brazing, soldering, or the like in addition to welding.

[0270] Unlike the embodiment, the tab of the second electrode 22 may be bonded to the inner circumferential surface of the side wall portion 11 of the battery can 10 and electrically connected thereto.

[0271] Also, unlike the above embodiment, the tab of the second electrode 22 may be joined to the cap 40 or the side wall 11 of the battery can 10 via a current collector plate (not shown).

[0272] In addition, the tab of the second electrode 22 or the current collecting plate connected thereto may be joined to both the inner circumferential surface of the side wall portion 11 and the cap 40 .

[0273] In addition, second electrode terminals may be separately provided on the cap 40, and the tabs of the second electrodes 22 and the current collector plates 31 may be connected to these second electrode terminals.

[0274] 27, the edge of the cap 40 is joined to the open end of the sidewall 11 of the battery can 10 to be electrically connected and hermetically fixed, thereby electrically connecting the second electrode 22 to the cap 40 and the battery can 10. The joining of the cap 40 and the battery can 10 may be performed by various methods capable of electrically connecting and hermetically joining, such as welding, brazing, or soldering.

[0275] Unlike the embodiment, it is needless to say that the cap 40 may be fixed to the open end of the side wall 11 of the battery can 10 by a pressure sealing method such as crimping. It should be understood that the above-described sealing structure of the liquid filling port can be applied to these structures as well.

[0276] High heat may be generated during the process of welding the cap 40 and the side wall 11. If electrolyte is injected into the battery can 10 before the welding process, the high heat generated during the welding process may cause the electrolyte to denature or ignite.

[0277] Therefore, as described above, after the processing of the welded portion (W) and the joined portion (M) where high heat is generated is completed, the electrolyte can be poured through the pouring port 42.

[0278] 28, the liquid inlet 42 may be provided at a position aligned with the core hollow portion 29 of the electrode assembly 20. Furthermore, the circular tube 48 defining the liquid inlet 42 may extend into the core hollow portion 29.

[0279] As a result, since the circular tube 48 extends further downward than the upper end of the separation membrane surrounding the inner periphery of the core hollow portion 29, during the process of injecting the electrolyte through the liquid inlet 42, the electrolyte discharged through the lower end of the liquid inlet 42 can be smoothly injected into the inside of the can 10 without damaging the separation membrane surrounding the inner periphery of the core hollow portion 29.

[0280] The injected electrolyte gradually fills the internal space of the can 10, and even when it reaches the bottom end of the circular tube 48, air is smoothly discharged to the outside of the can through the air holes 483, so that the electrolyte fills up to the top end of the electrode assembly 20 without creating an air pocket, allowing the electrode assembly 20 to be smoothly impregnated.

[0281] After the injection is completed, the finishing member 50 is inserted into the injection hole 42 as shown in Fig. 28, and the finishing member 50 is sealed and fixed with the sealing member 52 as shown in Fig. 29. At this time, the sealing member 52 also blocks the air hole 483.

[0282] [Fourth Example] A cap 40 to which the sealing structure for a pouring port is applied will be described in detail below with reference to FIGS. 30 to 34 as a fourth alternative embodiment of the present invention.

[0283] The cap 40 may be manufactured from a circular metal sheet. The cap 40 includes an electrode connector 41 recessed in a first direction corresponding to the axial direction of the battery cell 72. The electrode connector 41 may be formed by pressing the metal sheet.

[0284] The bottom surface of the electrode connector 41 is a portion that is closely bonded to the notched tab 27 of the second electrode 22 of the electrode assembly 20. The electrode connector 41, which is manufactured by pressing a metal sheet, has a thickness slightly thinner than the thickness of the metal sheet. Therefore, when a laser (L) is irradiated onto the surface of the electrode connector 41, the local heat generated by the laser melts and bonds the electrode connector 41 and the surface of the notched tab 27 that contacts the bottom surface thereof.

[0285] The electrode connectors 41 may be provided in plural. In the fourth embodiment, four electrode connectors 41 are disposed at equal intervals of approximately 90 degrees in the circumferential direction and formed in a radial pattern. The electrode connectors 41 extend in the radial direction, and the welds (W) for joining the electrode connectors 41 to the notched tabs 27 of the second electrode 22 of the electrode assembly 20 may have a weld line shape formed in the radial direction to correspond to the extension direction of the electrode connectors 41, as shown in FIG.

[0286] According to the embodiment, a linear weld (W) extending in the radial direction is formed for each of the plurality of electrode connecting portions 41.

[0287] The cap 40 provides a receiving surface 44, which is a surface that comes into contact with the ground when the battery can 10 is stood upright with the cap 40 of the battery can 10 facing the floor. The receiving surface 44 is provided at a position raised higher than the electrode connecting portions 41 and is disposed between two electrode connecting portions 41 that are adjacent in the circumferential direction.

[0288] As a result, the receiving surfaces 44 on both circumferential sides of the electrode connecting portion 41 are pressed with a jig to bring the electrode connecting portion 41 and the notched tab 27 into close contact, and then, as shown in Fig. 27, a laser is irradiated onto the surface of the electrode connecting portion 41 to weld the electrode connecting portion 41 and the notched tab 27. Then, the pressure of the jig along the length of the weld line on both sides of the weld line presses the electrode connecting portion 41 with the notched tab 27 in close contact, ensuring reliable welding.

[0289] A pair of electrode connectors 41 facing each other with respect to the center of the cap 40 are arranged on a straight line passing through the center of the cap 40. As a result, when forming a weld line, the weld line of two electrode connectors 41 aligned with each other may be formed with just one movement of a laser welder. For example, when the first electrode connector, the second electrode connector, the third electrode connector, and the fourth electrode connector are sequentially arranged along the circumferential direction of the cap 40 of the fifth embodiment, the first electrode connector and the third electrode connector may be welded at one time, or the second electrode connector and the fourth electrode connector may be welded at one time.

[0290] Furthermore, according to the embodiment, for example, when pressure is applied with a jig to the receiving surfaces 44 provided on both sides of the first electrode connecting part and the third electrode connecting part, which are arranged in a row around the center of the cap 40, the second-order moment of inertia formed by the recessed shapes of the second electrode connecting part and the fourth electrode connecting part is large, so that the cap 40 can move as a rigid body without twisting or bending despite the pressure of the jig.

[0291] In the embodiment, by configuring four electrode connectors 41 as described above, all four electrode connectors 41 can be welded with two laser scanning trajectories.

[0292] If too many electrode connectors 41 are formed, the strength of the cap 40 made of a metal sheet may be weakened. Also, if only two or three electrode connectors 41 are formed, it is difficult to form a cross section that can sufficiently secure the second moment of inertia along the circumferential direction.

[0293] When the four electrode connectors 41 are formed in a "+" shape on the cap 40 as in the embodiment, the welding process can be performed accurately and easily, the twist resistance and bending resistance of the cap 40 can be ensured, and weakening of the strength of the cap 40 due to the forming process can be prevented. That is, although the cap 40 also functions as a current collector, it is preferable that the cap 40 maintains its strength because of its primary function of finishing the open end of the battery can 10.

[0294] The radially outer edge of the cap 40 has a shape that is joined to the other axial end of the side wall portion 11 of the battery can 10. For this reason, the radially outer edge of the cap 40 preferably has a circular outer circumferential surface or inner circumferential surface.

[0295] The cap 40 of the fourth embodiment has an inner surface with a circular edge, and the electrode connecting portion 41 is formed to be recessed inward in the axial direction and radially inward from the inner surface. The circular inner surface of the cap 40 contacts the axial end surface of the side wall portion 11 of the battery can 10, as shown in Fig. 27, and can be welded by a laser irradiated radially inward from the outer periphery of the battery can 10 to form a joint (M).

[0296] At this time, the radially outer edge of the recessed portion for forming the electrode connecting portion 41 constitutes an outer wall. The outer wall may constitute a pressed-in outer wall 45 having an outer diameter corresponding to the inner diameter of the battery can 10. Then, when the cap 40 is assembled to the battery can 10, as shown in FIG. 27, the pressed-in outer walls 45 of the plurality of electrode connecting portions 41 slide against and press into the inner circumferential surface of the battery can 10, thereby guiding the central alignment of the cap 40 with respect to the battery can 10.

[0297] According to the fourth embodiment, the four push-in outer walls 45 are arranged evenly along the circumferential direction, and slide against the battery can 10 in a portion of the entire circumference of the inner circumferential surface. Therefore, the cap 40 can be easily pushed into the battery can 10 without increasing the pushing force of the cap 40.

[0298] In this way, the cap 40 of the embodiment has an advantage that it is easy to manufacture, since the pressed-in outer wall 45 is molded together when the electrode connecting portion 41 is molded.

[0299] Furthermore, according to the structure of the cap 40, a laser is irradiated in the radial direction to weld the cap 40 and the battery can 10. Therefore, even if an unexpected error causes the inner surface of the edge of the cap 40 and a portion of the end of the side wall 11 of the battery can 10 to become loosely attached, there is no risk of the laser being directly irradiated into the inside of the battery can 10 and damaging the electrode assembly 20.

[0300] According to the fourth embodiment, the receiving surface 44 of the cap 40 is located further outward in the axial direction than the joint (M) between the cap 40 and the battery can 10, so even if the battery can 10 in Fig. 29 is turned upside down and then stood upright, the joint (M) does not come into direct contact with the ground, making it easy to protect the joint (M). This protection can also be applied to the weld (W) using the same principle.

[0301] By applying the above-described cap 40, there is no need to use a current collector plate to electrically connect the tab of the second electrode 22 to the battery can 10, which reduces the number of parts and assembly steps, further secures internal volume, and increases energy density. Furthermore, since the cap 40 electrically connected to the battery can 10 is directly connected to the metal foil 23 of the second electrode of the electrode assembly 20 but is connected via a weld (W) that extends long in the radial direction, the current path is uniformly distributed and internal resistance can be significantly reduced.

[0302] The liquid inlet 42 is provided in the center of the cap 40. The liquid inlet 42 may be provided on the bottom surface of the cap 40, that is, on the electrode connecting portion 41 of the cap 40.

[0303] The liquid filling hole 42 formed in the center of the cap 40 can serve as a passageway through which equipment components can enter and exit for welding the first electrode terminal 13 and the current collector plate 31 of the first electrode 21. Therefore, unlike the assembly procedures shown in Figures 25 to 29 above, the cap 40 can be first joined to the tab of the second electrode 22 of the electrode assembly 20, as shown in Figure 35, and then inserted into the battery can 10 when the electrode assembly 20 is placed in the battery can.

[0304] 35 , the electrode assembly 20 can be housed in a battery can 10 with a current collector 31 joined to the tab of the first electrode 21 of the electrode assembly 20 and a cap 40 joined to the tab of the second electrode 22. The current collector 31 and the first electrode terminal 13 can be welded together through the liquid inlet 42 of the cap 40 and the hollow portion 29 of the core of the electrode assembly 20.

[0305] [Battery cell manufacturing method] The cap 40 of the fourth embodiment described above functions as a current collector for the second electrode while also retaining the original function of a cap, and therefore differs from conventional battery cells equipped with current collectors for the second electrode in terms of their manufacturing method.

[0306] In addition, the cap 40 has liquid filling holes 42, which can be used as passages for the joining process of the current collector plate 31 and the first electrode terminal 13, allowing for even more diverse configurations of the battery cell manufacturing method.

[0307] First, a method for manufacturing a battery cell will be described as a fifth embodiment of the present invention with reference to Fig. 36. This corresponds to the method for manufacturing a battery cell shown in Figs.

[0308] This includes the steps of preparing a battery can 10 to which a first electrode terminal 13 is fixed, and preparing an electrode assembly 20 including a first electrode 21 and a second electrode 22. At this time, the first electrode 21 and a current collector plate 31 may be joined and connected at one end of the electrode assembly 20 in the axial direction.

[0309] Next, the electrode assembly 20 is inserted into the battery can 10 with the current collector plate facing the bottom 12 of the battery can 10, and the current collector plate 31 of the electrode assembly 20 is joined to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by a method such as welding.

[0310] Next, the open end of the battery can 10 is covered with the cap 40. At this time, preferably, the electrode connecting portion 41 of the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 are joined in close contact with each other, and then the periphery of the open end of the battery can 10 and the edge of the cap 40 are joined together.

[0311] Next, the electrolyte is poured into the battery can 10 through the pouring port 42 of the cap 40 .

[0312] Finally, the above-described sealing structure for the liquid inlet is applied, and the liquid inlet 42 of the battery can 10 is sealed with a finishing member 50 and a sealing fixing material 52 for finishing.

[0313] These manufacturing methods not only eliminate the need for a separate current collector joining process for the second electrode 22, but also enable joining of the cap 40 to the second electrode 22 and the cap 40 to the battery can 10 before filling the interior of the battery can 10 with the electrolyte, thereby preventing the heat of joining from affecting the electrolyte.

[0314] Next, the manufacturing method disclosed in FIG. 41 will be described.

[0315] This includes preparing a battery can 10 to which a first electrode terminal 13 is fixed, and preparing an electrode assembly 20 having a first electrode and a second electrode. At this time, the first electrode 21 and a current collector plate 31 may be joined and connected to one axial end of the electrode assembly. Also, the electrode connector 41 of the cap 40 and the tab of the second electrode 22 may be joined and connected to the other axial end of the electrode assembly.

[0316] That is, the cap 40 may be first joined to the second electrode of the electrode assembly before the electrode assembly is housed in the battery can.

[0317] Next, the electrode assembly 20 is inserted into the battery can 10 with the current collector plate facing the bottom 12 of the battery can 10. During this process, the cap 40 covers the open end of the battery can 10.

[0318] Next, the current collector 31 of the electrode assembly 20 is joined to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by a method such as welding, and the periphery of the open end of the battery can 10 is joined to the edge of the cap 40.

[0319] Next, the electrolyte is poured into the battery can 10 through the pouring port 42 of the cap 40 .

[0320] Finally, the above-described sealing structure for the liquid inlet is applied, and the liquid inlet 42 of the battery can 10 is sealed with a finishing member 50 and a sealing fixing material 52 for finishing.

[0321] According to these manufacturing methods, a separate current collector joining operation is not required for the second electrode 22, and the cap 40 and the second electrode 22 and the cap 40 and the battery can 10 can be joined before the electrolyte is filled into the battery can 10, preventing the joining heat from affecting the electrolyte. Furthermore, the cap 40 can be integrated into the electrode assembly 20 in advance without being separately managed, further simplifying the assembly equipment.

[0322] In this way, when manufacturing a battery cell by applying the cap 40 having the core hollow portion 29 of the electrode assembly 20 and the liquid filling port 42 aligned in the axial direction, various manufacturing methods can be configured.

[0323] Furthermore, when sealing the liquid filling hole 42, strong pressure is not applied to the cap 40, nor is the cap 40 heated to a high temperature, so there is no risk of the internal structure of the battery can 10 being damaged or being denatured or ignited by heat.

[0324] [Battery pack and vehicle] 38, a battery cell 72 to which the above-described sealing structure for the liquid filling port is applied and / or a battery cell 72 to which the above-described manufacturing method is applied can be housed in a housing 71 of a battery pack 70. The battery pack 70 can be constructed using a battery module, which is an intermediate form of assembly, or, as shown in the figure, the battery pack 70 can be directly constructed without a battery module.

[0325] Since the battery cell 72 itself has a large volume, it is not particularly difficult to implement the battery pack 70 without using an intermediate structure such as a battery module. Furthermore, since the second electrode of the battery cell 72 is connected via a cap, the internal resistance is low and the energy density is higher. Therefore, the energy density of the battery pack 70 can be further increased.

[0326] In this way, the battery pack 70 with increased energy density can store the same amount of energy while reducing its volume and weight. Therefore, if the battery pack 70 using these battery cells 72 is installed in a vehicle such as an automobile 80 that uses electricity as its energy source, as shown in Fig. 39, the vehicle's mileage per unit of energy can be further increased.

[0327] It should be understood that the above-described embodiments are illustrative in all respects and are not limiting, and the scope of the present invention is defined by the following claims rather than the above detailed description. All modifications and variations within the meaning and scope of the following claims, as well as equivalent concepts, should be construed as being included within the scope of the present invention.

[0328] Although the present invention has been described above with reference to illustrative drawings, the present invention is not limited to 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 concept of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described and explained while the embodiments of the present invention are described above, it is natural that the effects that can be predicted by the configuration should also be recognized. [Explanation of symbols]

[0329] 10 cans 11 Side wall 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 1st electrode 22 2nd electrode 23 Metallic foil 24 Active material layer 25 Landed section 26 Ignorance 27 Notched tab 28 Separation membrane 29 Hollow core 31 Current collector plate 32 Terminal connection part 33 Ring section 34 Electrode connection part 40 Cap 41 Electrode connection part W welded section 42 Filling port 44 Receiving surface 45 Push-in exterior wall M joint 48 circular tube 481 Guide surface 483 Air hole 50 Finishing material (ball) 52 Sealing fixing material 54 Synthetic resin (layer) 56 Solder (lead-free solder) 70 Battery Pack 71 Housing 72 battery cells 80 vehicles

Claims

1. a can 10 having an open end at one end; an electrode assembly 20 housed inside the can 10; a cap 40 covering the open end of the can 10; a liquid inlet 42 provided on the can 10 or the cap 40; a finishing member 50 inserted into the inlet 42; and a sealing fixing member (52) that fixes the finishing member (50) inserted into the liquid inlet (42) within the liquid inlet (42), the liquid filling port 42 has a through section extending in a first direction crossing the exterior and interior of the battery cell, and has a through cross section defined by a location where an imaginary plane extending in a second direction intersecting the first direction and an inner circumferential surface of the liquid filling port 42 intersect; the finishing member 50 extends in the first direction and has a finishing cross section defined by an intersection between an imaginary plane extending in the second direction and an outer peripheral surface of the finishing member 50; At least a portion of the section of the finishing member 50 in the first direction is disposed within the through-section of the liquid inlet 42, The sealing fixing material 52 is interposed between the inner circumferential surface of the liquid pouring port 42 and the outer circumferential surface of the finishing member 50 in the second direction, The sealing fixing material 52 seals the space between the inner circumferential surface of the liquid pouring port 42 and the outer circumferential surface of the finishing member 50 in a sealing section which is at least a part of the section in the first direction, and fixes the finishing member 50 within the liquid pouring port 42, The sealing fixing material 52 has a melting point lower than the melting point of the can 10 or the cap 40 on which the liquid pouring hole 42 is provided and the melting point of the finishing member 50. Battery cell.

2. The minimum size of the through cross section of the liquid inlet 42 is smaller than the maximum size of the finishing cross section of the finishing member 50, The position in the first direction where the penetration cross section of the liquid inlet 42 has the smallest size is located further inside than the sealed section. The battery cell of claim 1 .

3. The liquid inlet 42 is defined by the inner circumferential surface of a circular tube 48 extending in a first direction from the can 10 or the cap 40. The battery cell of claim 1 .

4. The inner end of the circular tube 48 in the first direction extends in the axial direction so as to be inserted into the core hollow portion 29 of the electrode assembly 20. The battery cell of claim 3 .

5. The circular tube 48 is provided with an air hole 483 through which the air inside the can 10 is discharged when the electrolyte is poured through the pouring hole. The air hole 483 is disposed in the sealed section. The battery cell of claim 4 .

6. The outer peripheral surface of the finishing member 50 is not in direct contact with the inner peripheral surface of the liquid pouring port 42. The battery cell of claim 1 .

7. The sealing fixture 52 is provided by being integrally fixed to the outer circumferential surface of the finishing member 50. The battery cell of claim 6 .

8. The sealing fixing material 52 includes a synthetic resin layer 54 coated on the surface of the finishing member 50. The battery cell of claim 7 .

9. The elastic modulus of the sealing fastener 52 is smaller than the elastic modulus of the finishing member 50. The battery cell of claim 6 .

10. The finishing member 50 is made of a metal material. The battery cell of claim 9 .

11. the sealing fixture 52 has a sealing cross section defined by an intersection between an imaginary plane extending in the second direction and an outer circumferential surface of the sealing fixture 52, a sealing cross section of the sealing fastener 52 disposed in the sealed section is larger than a through cross section of the inlet 42 of the sealed section, and is compressed inward in the second direction by an inner circumferential surface of the inlet 42 to correspond to the through cross section; The battery cell of claim 9 .

12. The sealing fixing material 52 includes a section inward in the first direction from the sealing section, in which the sealing cross section gradually becomes smaller as it goes inward in the first direction. The battery cell of claim 11 .

13. The inner end of the sealing fixture 52 in the first direction covers the finishing member 50 in the first direction. The battery cell of claim 12 .

14. The finishing member 50 includes a section, which is located more inward in the first direction than the sealed section, in which the finishing cross section gradually becomes smaller as it goes more inward in the first direction. The battery cell of claim 11 .

15. The finishing member 50 is a ball 50, The sealing material 52 is provided integrally as a coating on the ball 50. The battery cell of claim 6 .

16. The inner circumferential surface of the liquid injection port 42 in the sealed section extends so as to be aligned in the first direction.

16. The battery cell of claim 15.

17. The outer peripheral surface of the finishing member 50 contacts the inner peripheral surface of the liquid pouring port 42. The battery cell of claim 1 .

18. The outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid pouring port 42 are in line contact with each other in the circumferential direction.

18. The battery cell of claim 17.

19. The outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42 contact each other in a section in which the through cross section of the liquid inlet 42 gradually decreases toward the inside in the first direction.

18. The battery cell of claim 17.

20. a rate at which the radius defining the through-section of the liquid inlet 42 decreases as the position becomes more inward in the first direction in a predetermined section inward in the first direction from a position where the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42 contact each other and a predetermined section inward in the first direction from the position where the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42 contact each other is constant; 20. The battery cell of claim 19.

21. The outer circumferential surface of the finishing member 50 and the inner circumferential surface of the liquid inlet 42 contact each other in a section where the finishing cross section of the finishing member 50 gradually decreases toward the inside in the first direction.

18. The battery cell of claim 17.

22. In a predetermined section inward in the first direction from a position where the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42 contact each other, the rate at which the finishing cross-section of the finishing member 50 decreases is greater than the rate at which the through cross-section of the liquid inlet 42 decreases as the finishing member 50 moves inward in the first direction.

18. The battery cell of claim 17.

23. In a predetermined section extending outward in the first direction from a position where the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42 contact each other, the rate at which the finishing cross-section of the finishing member 50 decreases is smaller than the rate at which the through cross-section of the liquid inlet 42 decreases as the finishing member 50 moves inward in the first direction.

18. The battery cell of claim 17.

24. The position where the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid pouring port 42 contact each other is located further inward in the first direction than the position where the finishing member 50 has the largest finishing cross section.

18. The battery cell of claim 17.

25. The sealed section is provided further outward in the first direction than a position where an outer peripheral surface of the finishing member 50 and an inner peripheral surface of the liquid pouring port 42 contact each other.

18. The battery cell of claim 17.

26. The finishing member 50 is made of a metal material. The sealing and fixing material 52 includes solder 56 that fills the space between the outer peripheral surface of the finishing member 50 and the inner peripheral surface of the liquid inlet 42 in the sealed section, with the outer peripheral surface of the finishing member 50 in contact with the inner peripheral surface of the liquid inlet 42.

26. The battery cell of claim 25.

27. The finishing member 50 is a ball 50.

27. The battery cell of claim 26.

28. The liquid inlet 42 is provided in the cap 40, The side edge of the open end of the can 10 and the edge of the cap 40 are thermally bonded. The battery cell of claim 1 .

29. The thermal joining of the can 10 and the cap 40 is performed by any one of welding, brazing, and soldering.

29. The battery cell of claim 28.

30. The electrode assembly 20 includes a first electrode 21 and a second electrode 22, and the tabs of the first electrode 21 and the tabs of the second electrode 22 are disposed on both sides of the electrode assembly 20 in the axial direction, respectively. A first electrode terminal 13 is fixed to a bottom 12 provided on the opposite side of the open end in the axial direction of the can 10 and is electrically insulated from the bottom 12. The first electrode 21 of the electrode assembly 20 is connected to the first electrode terminal 13 via a current collecting plate 31 joined to a tab of the first electrode 21.

29. The battery cell of claim 28.

31. The electrode assembly 20 includes a first electrode 21 and a second electrode 22, and the tabs of the first electrode 21 and the tabs of the second electrode 22 are disposed on both sides of the electrode assembly 20 in the axial direction, respectively. The cap 40 includes an electrode connection portion 41 that is thermally bonded to a tab of the second electrode 22 of the electrode assembly 20.

29. The battery cell of claim 28.

32. The thermal joining of the cap 40 and the tab of the second electrode 22 is performed by any one of welding, brazing, and soldering.

32. The battery cell of claim 31.

33. The liquid inlet 42 is provided in the center of the cap 40, The electrode connecting portion 41 extends radially around the liquid inlet 42.

32. The battery cell of claim 31.

34. The cap 40 includes a receiving surface 44 extending axially outward from the electrode connecting portion 41.

32. The battery cell of claim 31.

35. a can preparation step of preparing a can 10 having a side wall 11, a bottom 12 connected to one axial end of the side wall 11, and an open end provided at the other axial end of the side wall 11, and sealingly and insulatingly fixing a first electrode terminal 13 to the center of the bottom 12; a step of preparing an electrode assembly 20 including a first electrode 21 and a second electrode 22, the tabs of the first electrode 21 and the tabs of the second electrode 22 being disposed on opposite sides in the axial direction; a cap preparation step of preparing a cap 40 provided with a liquid inlet 42; After the can preparation step and the electrode assembly preparation step, a first electrode terminal connection step is performed in which the electrode assembly 20 is placed in the can 10 so that the tab of the first electrode 21 faces the bottom 12 of the can 10, and the tab of the first electrode 21 is connected to the first electrode terminal 13; a second electrode connecting step of connecting the cap 40 to the tab of the second electrode 22 after the electrode assembly preparing step and the cap preparing step; a cap fixing step of fixing the cap 40 to the can 10 after the first electrode terminal connecting step; a step of injecting an electrolyte into the can 10 after the steps of connecting the first electrode terminal, connecting the second electrode, and fixing the cap; and a filling port finishing step of inserting the finishing member 50 into the filling port 42 after the filling step and the plug preparation step, sealing the space between the inner peripheral surface of the filling port 42 and the outer peripheral surface of the finishing member 50 with a sealing and fixing material 52 having a melting point lower than the melting point of the cap 40 to which the filling port 42 is attached and the melting point of the finishing member 50, and sealing and fixing the finishing member 50 in the filling port 42; A method for manufacturing a battery cell.

36. The finishing step of the liquid inlet is performed by pushing the finishing member 50, the surface of which is coated with the sealing material 52, into the liquid inlet 42, and elastically compressing the sealing material 52 between the outer circumferential surface of the finishing member 50 and the inner circumferential surface of the liquid inlet 42.

36. The method of manufacturing the battery cell of claim 35.

37. The finishing step of the liquid inlet is performed by inserting a finishing member 50 into the liquid inlet 42, and soldering a sealing fixing material 52 into the space between the outer circumferential surface of the finishing member 50 and the inner circumferential surface of the liquid inlet 42 while the outer circumferential surface of the finishing member 50 is in line contact with the inner circumferential surface of the liquid inlet 42.

36. The method of manufacturing the battery cell of claim 35.

38. A battery cell according to any one of claims 1 to 34, Battery pack.

39. A battery pack according to claim 38, car.

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