Sealing structure for liquid injection port of battery can, battery cell comprising sealing structure, battery and vehicle

Abstract

The present invention relates to a structure for sealing a liquid injection port of a battery cell. The battery cell includes: a can having an open end at one end in an axial direction; an electrode assembly accommodated inside the can; a lid part for covering the open end of the canister; a liquid injection port provided at the cover portion; and a closing member inserted into the liquid injection port to complete the liquid injection port. And a sealing member sealed and fixed in a state of being inserted into the liquid injection port by a sealing and fixing material melted at a predetermined temperature. The closure member includes a ball made of a metal material. The sealing and fixing material may include a synthetic resin layer coated on a surface of the ball, or a solder filled between the surface of the ball and an inner circumferential surface of the liquid injection port while the ball is inserted into the liquid injection port to seal and fix the ball inside the liquid injection port.

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, and all contents disclosed in the documents of the above patent applications are included as part of this specification.

[0002] The present invention relates to a sealing structure of a liquid injection port of a battery can, a battery cell using the sealing structure, a method for manufacturing the battery cell, a battery pack including the battery cell, and a vehicle equipped with the battery pack. Background Art

[0003] The cylindrical battery cell is a structure in which a jellyroll-type electrode assembly is housed in a cylindrical metal can, and is more robust against impact and temperature than a pouch-type battery. Therefore, the demand for using a metal can type cell as a battery cell applied to a vehicle battery pack is increasing.

[0004] A process for manufacturing a battery cell using a cylindrical can includes: deep drawing a metal sheet to form a circular bottom and a circular tubular side wall member connected to the circular bottom; accommodating an electrode assembly in the can; and covering an open end of the side wall member with a cover.

[0005] Crimping or seam welding may be applied to a structure in which the open end of the battery can is covered with the cover portion and the cover portion and the battery can are fixed.

[0006] Reference Figure 1 , crimping is a method of fixing the cover 40 by physically pressing the edge of the cover 40 to the open end of the tank 10 with the gasket 91 interposed between the cover 40 and the open end of the tank 10. Since crimping is a physical fixing method without heating, it can be performed with the electrolyte solution filled in the tank. Therefore, the crimping method has the advantage that a separate liquid injection port structure and its sealing structure are not required. However, since crimping is more complex in structure than welding, there is a limitation in ensuring the internal volume of the tank accommodating the electrode assembly 20.

[0007] On the contrary, Figure 2 As shown, seam welding is a process of bringing the outer edge of the end of the side wall portion 11 of the battery can 10 into contact with the outer edge of the edge of the cover 40 and welding them in the circumferential direction of the cover 40 so as to ensure a larger volume of the electrode assembly that can be accommodated in the battery can due to the simplicity of the fixing structure of the cover 40. Therefore, seam welding is more advantageous in ensuring the electric capacity relative to the volume of the battery can.

[0008] However, when welding is performed by filling a battery can with an electrolyte solution and then covering the open end of the battery can with a lid, there is a possibility that the electrolyte solution may deteriorate or ignite due to a high temperature generated by welding.

[0009] For example, during seam welding, when the battery can and cover are made of SUS, the surface temperature may rise to 1400 degrees Celsius, which is the melting point of SUS. This high temperature heat may cause ignition of the electrolyte solution.

[0010] Therefore, when the cover is fixed by seam welding the open end of the battery can and the outer edge of the cover, a method can be applied: wherein, a battery can 10 having a liquid injection port provided at the bottom portion or a cover 40 having a liquid injection port 42 provided thereon is prepared; after the electrode assembly is accommodated in the battery can and the battery can 10 and the cover are seam welded, an electrolyte solution is injected through the liquid injection port 42 provided at the bottom portion of the cover or the battery can; and after the liquid injection is completed, the liquid injection port is closed and sealed.

[0011] For example, Figure 2 As shown, a closing member such as a metal ball 50 may be press-fitted into the liquid injection port 42 to be fixed to the liquid injection port 42 and seal the liquid injection port 42. That is, the metal ball 50 having a diameter larger than the diameter of the inner circumferential surface of the liquid injection port 42 is forcibly press-fitted into the liquid injection port 42, so that the inner circumferential surface of the liquid injection port 42 and the surface of the metal ball 50 are compressed together by their elastic deformation to achieve sealing.

[0012] However, since the sealing structure of the liquid injection port consumes the volume of the battery cell as much as the portion where the ball is pressed in, this structure is disadvantageous in terms of ensuring the internal volume of the tank. In addition, since a large pressure is applied to the electrode to force the ball 50 into the liquid injection port 42, there is a possibility that the electrode may be damaged.

[0013] Meanwhile, when thermal runaway occurs inside the can of the battery cell, the internal pressure of the can increases and causes an explosion. In order to prevent such an explosion, a venting structure may be applied to the can or the cover. The general venting structure uses the principle that the internal pressure increased due to the increase in internal temperature caused by thermal runaway tears the soft part 92 of the can or the cover to release the internal pressure. In addition, as Figure 1 As shown, the soft portion is realized by forming a notch 92 at a predetermined portion of the can or the cover to facilitate damage of the corresponding portion.

[0014] However, even when a welding method for fixing the cover portion is applied, which is advantageous in ensuring a larger internal volume of the can for accommodating the electrode assembly, the above-mentioned separate liquid injection port and its closing structure and exhaust structure consume the internal volume of the can, causing the internal volume of the can for accommodating the electrode assembly to be reduced again.

[0015] At the same time, it is also possible to consider implementing a venting structure through the liquid injection port. However, since the area of ​​the liquid injection port is small, it is difficult to damage the sealing member sealing the liquid injection port with pressure to lose the sealing and fixing force. Therefore, a sealing member that loses its sealing and fixing force due to heat when high temperature heat is generated inside the battery cell can be applied.

[0016] However, materials with low melting points such as synthetic resin materials generally have low rigidity and strength, making sealing and fixing forces weak. Therefore, using the material with low melting points itself as a closing member is bound to be a very unstable method of closing the liquid injection port. Summary of the invention

[0017] Technical issues

[0018] In order to solve the above problems, an object of the present invention is to provide a battery cell safety device, wherein an electrolyte solution can be injected through a liquid injection port, making seam welding of the cover possible, while the liquid injection port serves as a vent structure without the need for a separate vent structure.

[0019] Furthermore, another object of the present invention is to provide a structure of a battery cell, wherein a liquid injection port and a closed structure thereof do not consume a space for accommodating an electrode assembly, thereby maximizing the internal volume of a can accommodating the electrode assembly.

[0020] Furthermore, it is still another object of the present invention to provide a structure of a battery cell in which an electrolyte solution can be smoothly filled when injected into a can.

[0021] In addition, another object of the present invention is to provide a sealing structure for a liquid injection port and a battery cell using the sealing structure, wherein the liquid injection port can be sealed without applying strong force or high temperature heat.

[0022] In addition, another object of the present invention is to provide a sealing structure for a liquid injection port having excellent sealing and closing capabilities and smooth gas discharge when exhaust is required.

[0023] In addition, another object of the present invention is to provide a battery cell with high energy density and a vehicle-mounted battery pack using the battery cell.

[0024] The technical problem to be solved by the present invention is not limited to the above-mentioned purpose, and other purposes and advantages of the present invention that are not described can be understood by the following description and will be more clearly understood by the examples of the present invention. In addition, it is obvious that the purposes and advantages of the present invention can be embodied by the means indicated in the claims and their combinations.

[0025] Technical Solution

[0026] In order to solve the above problems, the present invention provides a closing structure for a liquid injection port of a battery cell, the closing structure comprising: a liquid injection port provided on a can or a cover; and a closing member inserted into and closing the liquid injection port.

[0027] The can of the battery cell may have an open end at one axial end. The electrode assembly may be accommodated in the can. The cover may cover the open end of the can accommodating the electrode assembly.

[0028] The closing member is fixed to and seals the liquid injection port while being inserted into the liquid injection port by a sealing and fixing material having a predetermined melting point.

[0029] The melting point may be a temperature at which the battery cell melts due to heat generated from thermal runaway. The melting point may be lower than the melting points of the closing member, the cover, and the can. The temperature may be equal to or higher than 100 degrees Celsius and equal to or lower than 500 degrees Celsius.

[0030] The closing member is firmly fixed in the liquid injection port by the sealing and fixing material. Without the sealing and fixing material, the closing member can easily fall off from the liquid injection port.

[0031] The closure member, the lid and the can may comprise a metallic material.

[0032] The closure member may comprise a ball.

[0033] The sealing and fixing material may include a synthetic resin layer coated on the surface of the ball.

[0034] When the ball is inserted into the liquid injection port, the sealing and fixing material is compressed between the inner peripheral surface of the liquid injection port and the surface of the ball, so that the ball is fixed to the liquid injection port and seals the liquid injection port.

[0035] When thermal runaway of the battery cell occurs, the synthetic resin layer may melt and lose the sealing function achieved by compressing the synthetic resin layer. As a result, the high-pressure gas inside the tank may be discharged to the outside through the liquid injection port.

[0036] The sealing and fixing material may include solder which is filled between the surface of the ball and the inner peripheral surface of the liquid injection port when the ball is inserted into the liquid injection port to fix the ball to the liquid injection port and seal the liquid injection port.

[0037] The solder may include lead-free solder.

[0038] When thermal runaway of the battery cell occurs, the solder melts. As a result, the solder cannot withstand the internal pressure of the tank. Then, the high-pressure gas inside the tank can be discharged to the outside through the liquid injection port.

[0039] The diameter of the ball can be equal to or smaller than the inner diameter of the liquid injection port. Therefore, when the sealing and fixing material is heated and loses its sealing force, the high-pressure gas inside the tank can be discharged through the gap between the inner circumference of the liquid injection port and the ball.

[0040] The liquid injection port includes a round tube extending in an axial direction, and the round tube may extend into a core hollow portion of the electrode assembly. A ball may be inserted into the round tube to be fixed to the round tube and seal the round tube.

[0041] Therefore, despite the structure of the liquid injection port and the exhaust structure, the length of the electrode assembly in the axial direction can be further ensured, thereby further ensuring the energy density relative to the volume of the battery cell.

[0042] The circular tube may be provided with air holes through which air inside the tank is discharged when the electrolyte solution is injected through the liquid injection port.

[0043] During the liquid injection process, the lower end of the round tube is set lower than the upper end of the electrode assembly. Therefore, the air inside the tank may be trapped and not discharged to the outside, thereby forming an air pocket in the space between the peripheral wall of the tank and the round tube. As a result, there is a risk that the portion of the electrode assembly present in this space may not be smoothly impregnated with the electrolyte solution.

[0044] The air hole can be set in the circular tube at a position higher than the upper end of the electrode assembly. As a result, no air pocket is formed in the space, and when the electrolyte solution is injected, the electrolyte solution can be filled smoothly.

[0045] After the liquid injection is completed and the ball is inserted into the liquid injection port, the air hole may be sealed by a sealing and fixing material that seals between the inner peripheral surface of the liquid injection port and the surface of the ball.

[0046] The pores can be sealed with solder. The diameter of the pores should be such that air can flow, but the solder will not flow into the pores due to its viscosity and surface tension.

[0047] In addition, in order to solve the above-mentioned problems, the present invention provides a battery cell, which includes: a can having an open end; an electrode assembly, which is accommodated in the can; a cover portion, which covers the open end of the can; a liquid injection port, which is arranged at the can or the cover portion; a closing member, which is inserted into the liquid injection port; and a sealing and fixing material, which fixes the closing member inserted in the liquid injection port to the liquid injection port.

[0048] The liquid injection port has a perforated section extending in a first direction spanning the exterior and interior of the battery cell, and has a cross section defined by an intersection of an imaginary plane extending in a second direction crossing the first direction and an inner peripheral surface thereof.

[0049] The closing member extends in the first direction and has a cross section defined by an intersection of an imaginary plane extending in the second direction and an outer peripheral surface thereof.

[0050] At least a portion of the closing member in the first direction is disposed within the perforated section of the liquid injection port.

[0051] The sealing and fixing material is interposed between the inner peripheral surface of the liquid injection port and the outer peripheral surface of the closing member in the second direction.

[0052] The sealing and fixing material seals the space between the inner circumference of the liquid injection port and the outer circumference of the closing member to provide a sealing section corresponding to at least a portion of the section in the first direction and fixes the closing member in the injection port.

[0053] The melting point of the sealing and fixing material is lower than the melting point of the can or lid portion provided with the liquid injection port and the melting point of the closing member.

[0054] The liquid injection port may have a minimum cross-section that is smaller than a maximum cross-section of the closing member, and may be disposed more inwardly than the sealing section in the first direction.

[0055] Therefore, it is possible to prevent the closing member from falling into the interior of the tank through the liquid injection port.

[0056] The liquid injection port may be defined by an inner circumferential surface of a circular tube extending from the tank or the cover portion in the first direction.

[0057] As a result, a sufficient section in which the sealing and fixing material is inserted can be ensured in the first direction for fixing the closing member inserted into the liquid injection port.

[0058] An inner end of the round tube in the first direction may extend in an axial direction to be inserted into a core hollow portion of the electrode assembly.

[0059] As a result, by preventing the round tube from consuming space in the battery cell in the axial direction, the energy density of the battery cell can be further improved.

[0060] The circular tube may be provided with an air hole for exhausting air in the tank when the electrolyte solution is injected through the liquid injection port.

[0061] The air hole may be provided on the sealing section. Therefore, even if the air hole is not blocked separately after the electrolyte solution is injected, the air hole may be shielded in the process of closing the liquid injection port.

[0062] The outer peripheral surface of the sealing member may not be in direct contact with the inner peripheral surface of the liquid injection port. Therefore, when the sealing and fixing material loses its sealing and fixing force, a space for exhausting the battery cell can be ensured between the sealing member and the inner peripheral surface of the liquid injection port.

[0063] The sealing and fixing material may be connected to an outer peripheral surface of the closing member in the sealing section, and may be in contact with an inner peripheral surface of the liquid injection port.

[0064] The sealing and fixing material may be arranged to be integrally fixed to the outer peripheral surface of the closing member.

[0065] The sealing and fixing material includes a synthetic resin layer coated on a surface of the closing member.

[0066] The elastic modulus of the sealing and fixing material may be lower than the elastic modulus of the closing member.

[0067] The elastic modulus of the sealing and fixing material may be smaller than the elastic modulus of a member constituting the inner peripheral surface of the liquid injection port.

[0068] The closure member may comprise a metallic material.

[0069] The sealing and fixing material has a cross section defined by an intersection of an imaginary plane extending in the second direction and an outer peripheral surface thereof.

[0070] The cross-section of the sealing and fixing material at the sealing section is larger than the cross-section of the liquid injection port at the sealing section, so that it is compressed inwardly along the second direction through the inner circumferential surface of the liquid injection port to correspond to the cross-section of the liquid injection port.

[0071] During the compression of the sealing and fixing material, a member defining an inner peripheral surface of the liquid injection port may hardly be deformed.

[0072] During the compression of the sealing and fixing material, the closing member may hardly deform.

[0073] The cross section of the closing member gradually decreases inwardly from the sealing section toward the inside of the tank in the first direction. Therefore, when the closing member is press-fitted into the liquid injection port, the sealing and fixing material can be smoothly inserted into the liquid injection port, and as the press-fitting proceeds, the sealing and fixing material can be naturally and elastically compressed in the second direction.

[0074] The inner end of the sealing and fixing material in the first direction can cover the closing member in the first direction. Therefore, when the closing member is press-fitted, the sealing and fixing material can be prevented from falling off the surface of the closing member due to the tension in the first direction.

[0075] The cross section of the closing member at a position further inward than the sealing section in the first direction can gradually become smaller toward the inside of the can in the first direction. Therefore, the thickness of the sealing and fixing material can be ensured, thereby preventing the sealing and fixing material from being broken due to tension in the first direction when the closing member is press-fitted.

[0076] The closing member may include a ball, and the sealing and fixing material may be integrally coated on the ball.

[0077] The inner circumferential surface of the liquid injection port extends in parallel to the first direction in the sealing section. That is, the cross section of the liquid injection port in the sealing section may be constant along the first direction.

[0078] Each of a cross-section of the liquid injection port and a cross-section of the closing member may be circular.

[0079] The sealing and fixing material may be circular in cross-section.

[0080] The outer peripheral surface of the sealing member may be in contact with the inner peripheral surface of the liquid injection port.

[0081] The outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port are in line contact in the circumferential direction.

[0082] When the closing member is strongly pressed into the liquid injection port, at least one of the inner circumferential surfaces of the closing member and the liquid injection port is elastically deformed so that the closing member and the liquid injection port can be in surface contact in the circumferential direction.

[0083] In contrast, when the closure member is gently inserted into the liquid injection port, for example, when a force equal to or slightly greater than gravity is applied to the closure member, the closure member is only inserted into the liquid injection port until the closure member contacts the inner circumferential surface of the liquid injection port. As a result, the inner circumferential surface of the closure member and the liquid injection port are substantially not elastically deformed, so that the closure member can be in line contact with the liquid injection port in the circumferential direction.

[0084] The outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port contact each other at a section where a cross section of the liquid injection port gradually decreases toward the inside of the tank along the first direction.

[0085] Therefore, when the sealing and fixing material loses its sealing force and fixing force, a space for exhaust can be ensured between the closing member and the inner peripheral surface of the liquid injection port.

[0086] The slope of the inner circumferential surface of the liquid injection port may be constant in predetermined sections further inside and outside in the first direction than where the outer circumferential surface of the closing member and the inner circumferential surface of the liquid injection port contact each other.

[0087] The shape of the liquid injection port and the shape of the closing member may correspond to the shape of a rotating body that rotates once around a central axis.

[0088] A rate of decrease of a radius of a cross section defining the liquid injection port in the first direction toward the interior of the tank may be constant.

[0089] The outer circumferential surface of the closing member and the inner circumferential surface of the liquid injection port may contact each other at a section where a cross section of the closing member gradually decreases toward the inside of the tank in the first direction.

[0090] In a predetermined section of the perforated section which is further inward in the first direction than the position where the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port contact each other, the rate at which the cross-section of the closing member 50 decreases toward the interior of the tank is greater than the rate at which the cross-section of the liquid injection port 42 decreases toward the interior of the tank.

[0091] In a predetermined section of the perforated section which is further outward in the first direction than the position where the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port contact each other, the rate at which the cross-section of the closing member 50 decreases toward the interior of the tank is smaller than the rate at which the cross-section of the liquid injection port 42 decreases toward the interior of the tank.

[0092] Therefore, in predetermined sections of the perforated section that are further inside and outside in the first direction than the position where the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port are in contact with each other so that friction force may not act, the outer peripheral surface of the closing member 50 and the inner peripheral surface of the liquid injection port may not be compressed against each other in the second direction.

[0093] A position where the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port contact each other may be disposed further inward in the first direction than a position where the closing member has a maximum cross section.

[0094] Therefore, when the sealing and fixing material loses its fixing force, the closing member can be easily disengaged outwardly from the liquid injection port in the first direction.

[0095] The sealing section may be disposed further outward in the first direction than a position where an outer peripheral surface of the closing member and an inner peripheral surface of the liquid injection port contact each other.

[0096] The closure member may comprise a metallic material.

[0097] The sealing and fixing material may include solder which is filled between the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port when the outer peripheral surface of the closing member contacts the inner peripheral surface of the liquid injection port.

[0098] The closure member may comprise a ball.

[0099] The electrode assembly may include a first electrode and a second electrode, and a tap of the first electrode and a tap of the second electrode may be disposed at both axial ends of the electrode assembly, respectively.

[0100] The joint may be a portion of metal foil of the first electrode and the second electrode respectively extending further outward in the axial direction from both axial ends of the electrode assembly.

[0101] The joint may comprise a slotted joint.

[0102] The joint may be bent in a radial direction.

[0103] Thus, the curved joint portion may provide a plane that is substantially perpendicular to the axial direction.

[0104] The joint may be bent radially inwardly.

[0105] First electrode terminals electrically insulated from and fixed to the bottom portion may be mounted on the bottom portion disposed on opposite sides of the open end of the can in the axial direction.

[0106] A bottom portion around the first electrode terminal may constitute the second electrode terminal 15, and a side wall portion connected to the bottom portion may also constitute the second electrode terminal.

[0107] The first electrode of the electrode assembly may be connected to the first electrode terminal through a current collecting plate 31 joined to a tab of the first electrode.

[0108] Therefore, the first electrode terminal may have a first polarity.

[0109] The cover portion may include an electrode connecting portion bonded to a tab of a second electrode of the electrode assembly by thermal bonding.

[0110] The thermal bonding may be performed before injecting the electrolyte solution.

[0111] The electrode connecting portion may be recessed inwardly from a surface of the cover portion in an axial direction.

[0112] The electrode connecting portion may extend flatly in the radial direction.

[0113] The thermal joining of the joint of the cover portion and the second electrode may include a process selected from welding, brazing and soldering.

[0114] The thermally joined portion may include a welded portion formed by laser light irradiated to the surface of the electrode connecting part in a scanning manner in a radial direction.

[0115] The liquid injection port may be provided at a central portion of the cover.

[0116] The electrode connection portion may extend radially around the liquid injection port.

[0117] A plurality of electrode connection parts may be provided. Each electrode connection part may be recessed inwardly toward the inside of the tank and extend in a radial direction.

[0118] Four electrode connection portions may be provided.

[0119] The edge of the open end of the can may be joined to the edge of the cover by heat bonding.

[0120] The thermal bonding of the can and the cover includes a process selected from welding, brazing and soldering.

[0121] Therefore, the cover portion, the side wall portion connected to the cover portion, and the bottom portion connected to the side wall portion may have the second polarity.

[0122] The thermal bonding may be performed before injecting the electrolyte solution.

[0123] The cover portion may have a base surface extending outward from the electrode connecting portion in an axial direction.

[0124] The height of the junction area between the cover and the tank can be lower than the height of the base surface, but higher than the height of the electrode connecting portion. Therefore, the junction area can be protected, the closed structure of the liquid injection port can be protected, and because the liquid injection port is placed lower than the base surface, exhaust can be smoothly performed.

[0125] The invention provides a method for manufacturing a battery cell using the sealing structure of the liquid injection port.

[0126] The manufacturing method includes a can preparation step: preparing a can having a side wall portion, a bottom portion connected to one axial end of the side wall portion, and an open end arranged at the other axial end of the side wall portion; and sealing, insulating and fixing a first electrode terminal at the center of the bottom portion.

[0127] The manufacturing method comprises an electrode assembly preparation step: preparing an electrode assembly, wherein the electrode assembly is provided with a first electrode and a second electrode, wherein a joint of the first electrode and a joint of the second electrode are respectively provided at two axial sides thereof.

[0128] The manufacturing method comprises a cover preparation step: preparing a cover provided with a liquid injection port.

[0129] The manufacturing method includes a first electrode terminal connecting step: after the can preparation step and the electrode assembly preparation step, the electrode assembly is accommodated in the can in a manner that the first electrode tab faces the bottom portion of the can, and the first electrode tab and the first electrode terminal are connected.

[0130] The manufacturing method includes a second electrode connecting step of connecting the cover to the connector of the second electrode after the electrode assembly preparing step and the cover preparing step.

[0131] The manufacturing method includes a cover portion fixing step of fixing the cover portion to the can after the first electrode terminal connecting step.

[0132] The manufacturing method includes a liquid injection step of injecting an electrolyte solution into the can after the first electrode terminal connecting step, the second electrode connecting step, and the cover fixing step.

[0133] The manufacturing method includes a liquid injection port closing step: after the liquid injection step and the cover preparation step, the closing member is inserted into the liquid injection port; and a sealing and fixing material having a melting point lower than the melting point of the cover provided with the liquid injection port and the melting point of the closing member is used to seal the space between the inner peripheral surface of the liquid injection port and the outer peripheral surface of the closing member, and the closing member is fixed in the injection port.

[0134] According to the manufacturing method, thermal bonding of the electrode assembly and the cover and thermal bonding of the can and the cover may be performed before injecting an electrolyte solution to prevent bonding heat from affecting the electrolyte solution.

[0135] The liquid injection port closing step may be performed by press-fitting a closing member on which a sealing and fixing material is coated into the liquid injection port to elastically compress the sealing and fixing material between an outer peripheral surface of the closing member and an inner peripheral surface of the liquid injection port.

[0136] The liquid injection port closing step can be performed by soldering the outer peripheral surface of the closing member to the inner surface of the liquid injection port with a sealing and fixing material while the closing member is inserted into the liquid injection port and the outer peripheral surface of the closing member is in line contact with the inner peripheral surface of the liquid injection port.

[0137] The present invention provides a battery pack including a battery cell.

[0138] Furthermore, the present invention provides a vehicle equipped with a battery pack.

[0139] Beneficial Effects

[0140] According to the present invention, when closing the liquid injection port, by using a sealing and fixing material that fixes the closing member and seals the liquid injection port and is capable of losing the sealing force and / or fixing force at a predetermined melting point, the electrolyte solution can be injected through the liquid injection port while allowing the seam welding of the cover portion, so that the liquid injection port itself is used as a venting structure without the need for a separate venting structure.

[0141] Furthermore, according to the present invention, since a structure for fixing a cover and a can and a structure for fixing a cover and a tab of an electrode do not consume space, the energy density of a battery cell can be improved.

[0142] In addition, according to the present invention, since the liquid injection port having a circular tubular shape extends into the core hollow portion of the electrode assembly, the liquid injection port and its closed structure do not consume the space for accommodating the electrode assembly. Therefore, the internal volume of the tank for accommodating the electrode assembly is maximized, thereby increasing the energy density of the battery cell. In addition, since the outer periphery of the liquid injection port having a circular tubular shape supports the diaphragm surrounding the inner circumferential surface of the core hollow portion, the electrolyte solution may not damage the diaphragm surrounding the inner circumferential surface of the core hollow portion during the injection of the electrolyte solution.

[0143] Furthermore, according to the present invention, since air inside the can is smoothly discharged through the pores when injecting the electrolyte solution and the pores are sealed when the liquid injection port is sealed, the electrode assembly can be smoothly impregnated with the electrolyte solution.

[0144] According to the present invention, since a pressing force strong enough to cause elastic deformation is not applied to the inner peripheral surface of the liquid injection port or the closing member, there is no risk of the cover portion being deformed or the electrodes in the battery being damaged.

[0145] According to the present invention, since high-temperature heat is not generated when the liquid injection port is closed, it is possible to prevent heat applied when the liquid injection port is closed from being transferred to the electrolyte solution or the electrode assembly and affecting battery performance.

[0146] According to the present invention, when closing the liquid injection port, a closing member having high strength and rigidity is used to close most of the cross-section of the liquid injection port, and a sealing and fixing material that provides an exhaust function due to its low melting point is inserted between the inner circumferential surface of the injection port and the closing member to fix the closing member to the liquid injection port.

[0147] As described above, according to the present invention, a sealing and fixing material is arranged in the space between a closing member having sufficient strength and rigidity and the inner peripheral surface of the liquid injection port, and is prevented from being exposed to the outside, thereby protecting the sealing and fixing material having lower strength and rigidity from damage caused by external impact, and the sealing and fixing material is reinforced by utilizing the inner peripheral surface of the liquid injection port and the closing member, thereby advantageously ensuring both the sealing function and the exhaust function.

[0148] In addition to the above-described advantageous effects, specific effects of the present invention will be further described while describing specific details of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0149] Figure 1 and Figure 2 is a diagram showing a method for closing a cover portion and an electrolyte solution inlet of a conventional battery can.

[0150] Figures 3 to 8 1 and 2 are diagrams showing a sealing structure and an exhaust structure of a liquid injection port according to a first embodiment of the present invention.

[0151] Figures 9 to 16 1 and 2 are diagrams showing a sealing structure and an exhaust structure of a liquid injection port according to a second embodiment of the present invention.

[0152] Fig.17 is a perspective view of a battery cell according to a third embodiment.

[0153] Fig.18 and Fig.19 are perspective views respectively showing states before and after laminating a first electrode, a second electrode, and a separator for manufacturing an electrode assembly to be housed in a battery can, Fig. 20 yes Fig.19 A plan view of the stacked state.

[0154] Fig.21 and Fig. 22 is through Fig.19 and Fig. 20 A perspective view and a side view of an electrode assembly manufactured by winding a laminate into a core type.

[0155] Fig.23 and Fig.24 is a perspective view showing an electrode assembly with a current collecting plate attached to an upper portion thereof and without a current collecting plate attached to a lower portion thereof.

[0156] Fig.25 It shows that Fig.23 and Fig.24 A cross-sectional view of a process of housing an electrode assembly into a battery can.

[0157] Fig.26 is a cross-sectional view illustrating a process of welding a first electrode terminal and a current collecting plate.

[0158] Fig. 27 is a cross-sectional view showing a process of joining the electrode connecting portion of the cover to the tab of the second electrode of the electrode assembly and joining the edge of the cover to around the open end of the battery can with the cover covering the open end of the battery can.

[0159] Fig.28 and Fig.29 1 is a diagram showing a process of injecting an electrolyte solution through a liquid injection port and sealing the liquid injection port.

[0160] Figure 30 to Figure 32 1 and 2 are an upper perspective view, a lower perspective view, and a plan view of a cover according to a fourth embodiment.

[0161] Fig.33 and Fig.34 yes Fig.32 A cross-sectional view of the corresponding part.

[0162] Fig.35is a perspective view showing a cover portion attached to a lower portion of an electrode assembly.

[0163] Fig.36 and Fig.37 1 and 2 are flowcharts showing methods of manufacturing a battery cell having a closing structure of a liquid injection port applied thereto according to a fifth embodiment and a sixth embodiment, respectively.

[0164] Fig.38 and Fig.39 A battery pack having the battery cell according to the embodiment applied thereto, and a vehicle equipped with the battery pack are shown.

[0165] Description of Reference Numerals

[0166] 10: can; 11: side wall portion; 12: bottom portion; 13: positive terminal (first electrode terminal); 14: terminal gasket; 15: negative terminal (second electrode terminal); 19: insulator; 20: electrode assembly; 21: first electrode; 22: second electrode; 23: metal foil; 24: active material layer; 25: coated area; 26: uncoated area; 27: slotted joint; 28: separator; 29: core hollow portion; 31: current collector; 32: terminal connection 33: ring; 34: electrode connection; 40: cover; 41: electrode connection; W: welding part; 42: liquid injection port; 44: base surface; 45: press-fit outer wall; M: joint area; 48: round tube; 481: guide surface; 483: air hole; 50: closing member (ball); 52: sealing and fixing material; 54: synthetic resin (layer); 56: solder (lead-free solder); 70: battery pack; 71: shell; 72: battery cell; 80: vehicle DETAILED DESCRIPTION

[0167] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0168] The present invention is not limited to the embodiments disclosed below, and various changes can be applied, and various changes can be implemented in various forms. The embodiments provided herein are only used to make the disclosure of the present invention complete and to enable those skilled in the art to fully understand the scope of the present invention. Therefore, the present invention is not limited to the embodiments disclosed below, and it should be understood that the present invention includes all changes and equivalents contained in the technical spirit and scope of the present invention, and the replacement or addition of the configuration of one embodiment with the configuration of another embodiment.

[0169] The accompanying drawings are only used to facilitate the understanding of the embodiments disclosed herein, and it should be understood that the technical concept disclosed herein is not limited by the accompanying drawings and includes all changes, equivalents and substitutions to the spirit and technical scope of the present invention. In the accompanying drawings, although the size or thickness of the components may be exaggeratedly increased or reduced for the sake of ease of understanding, etc., this should not be interpreted as limiting the scope of protection of the present invention.

[0170] The terms used herein are only used to describe specific embodiments or examples and are not intended to limit the present invention. In addition, unless the context clearly stipulates otherwise, the expression in the singular also includes the expression in the plural. Here, terms such as "include" and "comprise" are intended to indicate the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification. That is, it should be understood that the terms such as "include", "comprise" used herein should not exclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0171] Although terms including ordinal numbers such as "first" and "second" may be used to describe various components, these components are not limited by these terms. The terms are used only for the purpose of distinguishing one component from another.

[0172] It should be understood that when an element is referred to as being "connected" to another element, the element may be directly connected to the other element, or an intermediate element may exist in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there is no intermediate element in between.

[0173] When an element is referred to as being 'on' or 'under' another element, it should be understood that intervening elements may be present in between, and the element may also be directly on or under the other element.

[0174] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the relevant technical context, and unless explicitly defined herein, terms such as those defined in commonly used dictionaries should not be interpreted in an ideal or overly formal sense.

[0175] Throughout the specification, unless explicitly stated otherwise, “A and / or B” means A, B, or A and B, and “C to D” means from equal to or higher than C to equal to or lower than D, unless explicitly stated otherwise.

[0176] In the description of the implementation scheme, "axial direction" refers to "the direction in which the axis of the winding center constituting the cake roll type electrode assembly extends", "radial direction" refers to "the direction toward (centripetal) or away from (centrifugal) the axis", and "circumferential direction" refers to "the direction around the axis".

[0177] [First embodiment]

[0178] In the following, reference is made to Figures 3 to 8 , a sealing structure of a liquid injection port according to a first embodiment of the present invention will be described.

[0179] The liquid injection port 42 according to the first embodiment is provided at the central portion of the cover 40 .

[0180] The inner side surface of the cover portion 40 is electrically connected to the tab of the second electrode of the electrode assembly 20 housed in the can 10 of the battery cell. The edge of the cover portion 40 is engaged with the edge of the open end of the can 10 and electrically connected.

[0181] The electrolyte solution is injected into the tank 10 through the liquid injection port 42 of the cover 40. After the injection of the electrolyte solution is completed, the closing member 50 is inserted into the liquid injection port 42, and the closing member 50 is fixed to the inner peripheral surface of the liquid injection port 42, and the liquid injection port 42 is sealed with the sealing and fixing material 52.

[0182] The cover part 40 may be manufactured by molding a metal sheet using a press jig. The liquid injection port 42 may be manufactured by drawing a central portion of the cover part 40 in a first direction.

[0183] The first direction may be a direction across the outside and the inside of the battery cell.

[0184] The liquid injection port 42 may be defined by a circular tube 48 extending from the central portion of the cover 40 in the first direction. That is, the inner circumference of the circular tube 48 defines the liquid injection port 42. Hereinafter, it should be understood that the inner circumference of the liquid injection port 42 refers to the inner circumference of the circular tube 48.

[0185] The liquid injection port 42 has a perforated section T extending in a first direction, and has a cross section defined by an intersection of an imaginary plane extending in a second direction crossing the first direction and an inner peripheral surface of the liquid injection port 42 .

[0186] The first direction may be a direction corresponding to the axial direction of the electrode assembly 20 and the can 10. In addition, the second direction may correspond to the radial direction of the electrode assembly and the can. The first direction and the second direction may be orthogonal.

[0187] The cross section of the liquid injection port 42 defined by the inner peripheral surface of the circular tube 48 may be circular.

[0188] The inner circumference of the round tube 48 extending in the axial direction may have a substantially constant cross section in the axial direction. Strictly speaking, due to the nature of the drawing process, the round tube 48 may have a shape in which the radius gradually decreases toward the inside of the tank in the first direction. However, when only the minimum inclination required for removing the mold after processing is given, it can be considered to have a substantially constant cross section.

[0189] The area where the round tube 48 is connected to the cover 40 may be provided with a guide surface 481, which is a rounded portion whose radius gradually decreases from R5 to R2 toward the inside of the tank 10 in the first direction. The rounded portion is naturally formed in the drawing process for manufacturing the round tube 48, and the rounded portion can be used as a guide surface for guiding the closing member 50 to be inserted into the liquid injection port 42.

[0190] The length of the circular tube 48 extending in the first direction defines a perforated section T of the liquid injection port 42. The perforated section T of the liquid injection port 42 may substantially correspond to the diameter of the closing member 50 or the synthetic resin layer 54. Therefore, when the closing member 50 is fixed to the liquid injection port 42 and seals the liquid injection port 42, the closing member 50 may be prevented from significantly protruding into or from the liquid injection port 42 in the first direction.

[0191] Alternatively, the inner end of the circular tube 48 in the first direction may extend inwardly in the second direction similar to an inwardly folded edge to have a reduced radius R1.

[0192] The liquid injection port 42 has a substantially constant total diameter along the first direction so that its cross section may have a substantially constant shape, and its outer end in the first direction has the shape of a guide surface 481 and its inner end in the first direction may have an inwardly folded shape.

[0193] The radius R2 of the liquid injection port 42 is smaller than the radius of the core hollow portion 29 of the electrode assembly 20 .

[0194] The actual radius R2 of the liquid injection port 42 may be equal to or greater than 1 mm and equal to or less than 10 mm. Preferably, the radius R2 may be greater than or equal to 2 mm and less than or equal to 8 mm.

[0195] The closing member 50 may include a ball 50 made of a metal material, and the sealing and fixing material 52 may include a synthetic resin having a predetermined thickness coated on a surface of the metal ball 50 .

[0196] The elastic modulus of the material of the sealing and fixing material 52 is smaller than the elastic modulus of the material of the ball 50 and the elastic modulus of the material of the cylindrical tube 48 .

[0197] The elastic modulus of the sealing and fixing material 52 may be 0.2 times or less than the elastic modulus of the ball 50 and the cylindrical tube 48 .

[0198] The sealing and fixing material 52 may be coated on the entire surface of the metal ball 50. Therefore, the closing member 50, the surface of which is coated with the synthetic resin layer 54, has no orientation, thereby facilitating manufacturing and handling.

[0199] It can be seen that the cross-sections of the closure member 50 having a spherical shape defined by a plane perpendicular to the first direction are all circular. In addition, it can be seen that the closure member 50 has a maximum cross-section with a radius R3 at the central portion in the first direction, and the radius gradually decreases away from the central portion in the first direction toward the inside or outside of the tank, and the cross-section gradually decreases accordingly.

[0200] The sealing and fixing material 52 may have a cross section defined by the intersection of an imaginary plane extending in the second direction and the outer peripheral surface of the sealing and fixing material 52. Since the sealing and fixing material 52 is also laminated to a predetermined thickness on the surface of the metal ball 50, it can be seen that the cross section of the sealing and fixing material 52 is similar to that of the closing member 50. However, it can be seen that the sealing and fixing material 52 has a larger cross section corresponding to its thickness compared to the closing member 50.

[0201] Hereinafter, in the description of the closing member 50 and the sealing and fixing material 52, since the cross-section of the closing member 50 and the cross-section of the sealing and fixing material 52 are both circular, the areas of the cross-sections are compared based on their radii.

[0202] The thickness of the sealing and fixing material 52, i.e., R4-R3, may be about 0.1 mm or more and 5.0 mm or less. When the thickness is less than 0.1 mm, there is a possibility that the sealing and fixing material 52 may be damaged during the press-fitting process of the closing member 50. Even when the sealing and fixing material 52 is not damaged, it may be difficult to ensure the sealing force. When the thickness is 5.0 mm or more, since the diameter of the liquid injection port 42 is limited, the metal ball 50 must be smaller, resulting in the metal ball 50 not being properly used as a frame to support the overall shape of the sealing and fixing material 52.

[0203] The radius R3 of the maximum cross section of the closing member 50 is equal to or smaller than the radius R2 of the cross section of the liquid injection port 42. In this embodiment, the maximum cross section of the closing member 50 is illustrated to be slightly smaller than the cross section of the liquid injection port 42. That is, the difference R2-R3 may be approximately greater than 0 mm and equal to or smaller than 2.0 mm.

[0204] The radius R4 of the maximum cross section of the sealing and fixing material 52 is greater than the radius R2 of the cross section of the liquid injection port 42. The thickness R4-R3 of the sealing and fixing material 52 is approximately 1.1 to 5 times the difference R2-R3 between the inner diameter R2 of the liquid injection port 42 and the radius R3 of the ball 50.

[0205] When the metal ball 50 coated with the synthetic resin layer 54 is press-fitted into the liquid injection port 42, the synthetic resin layer 54 is compressed, and the metal ball 50 is also fitted into the liquid injection port 42. Here, since the diameter of the metal ball 50 is not larger than the inner diameter of the liquid injection port 42, a large pressing force is not required, and the amount of deformation of the metal ball 50 and the circular tube 48 is smaller than the amount of deformation of the synthetic resin layer 54.

[0206] When the closing member 50 is inserted into the liquid injection port 42, at least a portion of the closing member 50 in the first direction is disposed within the perforated section T of the liquid injection port 42. Preferably, the center of the ball 50 may be disposed at the center of the circular tube 48 in the length direction.

[0207] With the closing member 50 inserted in the liquid injection port 42 , the sealing and fixing material 52 is interposed between the inner peripheral surface of the liquid injection port 42 and the outer peripheral surface of the closing member 50 in the second direction.

[0208] The sealing and fixing material 52 shields the space between the inner circumference of the liquid injection port 42 and the outer circumference of the closing member 50 in the sealing section S, which is at least a portion of the perforated section in the first direction and fixes the closing member 50 in the liquid injection port 42 .

[0209] The sealing section S is preferably arranged substantially in a central portion of the perforated section T.

[0210] The cross-section of the sealing and fixing material 52 disposed in the sealing section S is larger than the cross-section of the liquid injection port 42 in the sealing section. Therefore, the sealing and fixing material 52 is compressed inwardly along the second direction by the inner circumferential surface of the liquid injection port 42, thereby corresponding to the cross-section of the liquid injection port 42.

[0211] The point A1 at which the maximum cross-section of the closure member 50 is disposed is approximately located in the center of the sealing section S.

[0212] Since the sealing and fixing material 52 has a shape corresponding to the surface of a sphere, its cross section gradually decreases inwardly from the sealing section S toward the inside of the tank in the first direction. Therefore, when the closing member 50 is press-fitted into the liquid injection port 42, the sealing and fixing material 52 can be smoothly inserted into the liquid injection port 42, and as the press-fitting proceeds, the sealing and fixing material 52 can be naturally and elastically compressed in the second direction.

[0213] Since the sealing and fixing material 52 surrounds the entire metal ball 50, the inner end of the sealing and fixing material 52 covers the closing member 50 in the first direction. As a result, when the closing member 50 is press-fitted, the sealing and fixing material 52 can be prevented from falling off the surface of the closing member 50 due to the tension in the first direction.

[0214] Since the closing member 50 is a metal ball 50, its cross section gradually decreases in the first direction from the sealing section S toward the inside of the can. Therefore, the thickness of the sealing and fixing material 52 laminated on the surface of the closing member 50 can be ensured in the corresponding section, so that the sealing and fixing material 52 can be prevented from being broken due to the tension in the first direction when being press-fitted in the closing member 50.

[0215] The sealing and fixing material 52 has a lower melting point than the cap 40 or the can 10 and the closing member 50 provided with the liquid injection port 42. The synthetic resin layer 54 may have a melting point equal to or higher than 100 degrees Celsius and equal to or lower than 300 degrees Celsius.

[0216] Therefore, when thermal runaway of the battery cell occurs, the synthetic resin layer 54 melts and loses its sealing force and its fixing force to the ball 50, as shown in FIG. Figure 8 As a result, exhaust can be smoothly performed through the space between the ball 50 and the inner peripheral surface of the liquid injection port 42.

[0217] A radius R1 of a minimum cross section of the liquid injection port 42 is located at an inner end A2 of the liquid injection port 42 in the first direction, and is smaller than a radius R3 of a maximum cross section of the closing member 50 .

[0218] The position A1 of the minimum cross section of the liquid injection port 42 in the first direction is located further inward than the sealing section S. Therefore, even when the sealing and fixing material 52 melts and loses its fixing force on the closing member 50, there is no risk of the closing member 50 falling into the tank 10 through the liquid injection port 42.

[0219] Meanwhile, the round tube 48 defining the liquid injection port 42 may extend into the core hollow portion 29 of the electrode assembly 20 in the axial direction. The upper end of the separator wound on the inner circumference of the core hollow portion of the electrode assembly 20 is disposed higher than the lower end of the round tube 48.

[0220] Therefore, a phenomenon in which the separator is loosened or deformed due to the flow of the electrolyte solution that occurs when the electrolyte solution injected into the liquid injection port 42 hits the upper end of the separator at the inner peripheral surface of the core hollow portion 29 can be prevented.

[0221] Furthermore, since there is no need to secure a separate space for adding the liquid injection port and its closing structure, the energy density of the battery cell is increased while adding the liquid injection port and the exhaust structure.

[0222] Furthermore, since the joints of the can 10 , the cover 40 , and the electrodes are joined at a high temperature, such as by welding, before the electrolyte solution is injected, the assembly process of the cover 40 does not have any adverse effect on the electrolyte solution.

[0223] [Second Embodiment]

[0224] In the following, reference will be made to Figures 9 to 16 The sealing structure of the liquid injection port according to the second embodiment of the present invention is described. The second embodiment will be described focusing on the differences from the first embodiment. Therefore, it is obvious that the content not described in one embodiment can be understood from the description of another embodiment. In addition, it should be understood that the configuration of one embodiment is applicable to other embodiments, and replacement, deletion or addition between the configurations of different embodiments is also possible.

[0225] The liquid injection port 42 may be defined by a circular tube 48 extending from the central portion of the cover portion 40 in a first direction. According to the first embodiment, a liquid injection port 42 having a substantially constant cross-section in the first direction is illustrated. In contrast, the perforation area of ​​the liquid injection port 42 according to the second embodiment gradually decreases toward the interior of the tank in the first direction. That is, the circular tube 48 defining the liquid injection port 42 may be a tapered circular tube as shown in the figure. The cone angle relative to the first direction may be approximately 1 to 5 degrees. That is, the rate of decrease of the radius of the cross-section of the liquid injection port 42 toward the interior of the tank in the first direction may be constant.

[0226] Therefore, the radius of the cross section of the liquid injection port 42 decreases from R5 to R2 along the rounded inner circumference of the guide surface 481 , and then steadily decreases to R1 toward the inside of the tank in the first direction.

[0227] The closing member 50 may be a spherical metal ball 50. The radius R3 of the closing member 50 is smaller than the maximum radius R2 of the tapered section of the liquid injection port 42 and larger than the minimum radius R1 thereof. The radius R3 of the closing member 50 may be determined in such a manner that when the closing member 50 is inserted into the liquid injection port 42, the closing member 50 is located near the central portion of the perforated section T of the liquid injection port 42.

[0228] Unlike the first embodiment, the sealing and fixing material 52 according to the second embodiment can be provided separately from the closing member 50. In addition, the sealing and fixing material 52 according to the second embodiment fills the space between the outer peripheral surface of the closing member 50 and the inner peripheral surface of the liquid injection port 42 when the closing member 50 is inserted into the liquid injection port 43, fixes the closing member 50 to the liquid injection port 42, and seals the space between the closing member 50 and the liquid injection port 42.

[0229] The sealing and fixing material 52 may include a solder 56 having a lower melting point than the cap 40 or the ball 50. The solder 56 may include a lead-free solder. The melting point of the solder 56 may be equal to or higher than 300 degrees Celsius and equal to or lower than 500 degrees Celsius.

[0230] Therefore, when the sealing and fixing material 52 is melted to fill the space between the outer peripheral surface of the closing member 50 and the inner peripheral surface of the liquid injection port 42 , the inner peripheral surface of the liquid injection port 42 and the closing member 50 can be kept in a solid state.

[0231] According to the sealing structure of the liquid injection port of the second embodiment, first, the sealing member 50 is inserted into the liquid injection port 42, as shown in FIG. Fig.12 As a result, the outer peripheral surface of the closing member 50 comes into contact with the inner peripheral surface of the liquid injection port 42 .

[0232] The closing member 50 is not strongly pressed into the liquid injection port 42. That is, the closing member 50 is not firmly or forcefully fitted into the liquid injection port 42. The closing member 50 is inserted into the liquid injection port 42 with a slight pressure. For example, the pressure may be a force equal to gravity or a force slightly greater than gravity.

[0233] When the closing member 50 is inserted into the liquid injection port 42 in this manner, the closing member 50 is only pressed into the liquid injection port 42 until the closing member 50 contacts the inner peripheral surface of the liquid injection port 42. When the closing member 50 is inserted into the liquid injection port 42 with a relatively light pressure, the closing member 50 and the inner peripheral surface of the liquid injection port 42 are substantially not elastically deformed. As a result, the outer peripheral surface of the closing member 50 and the inner peripheral surface of the liquid injection port 42 are substantially in line contact with each other in the circumferential direction.

[0234] This can be distinguished from a forced insertion method in which the closing member 50 and the liquid injection port 42 are in surface contact with each other in the circumferential direction due to elastic deformation of at least one of the inner circumferential surfaces of the closing member 50 and the liquid injection port 42 caused by forcefully pressing the closing member 50 into the liquid injection port 42.

[0235] Since the circular tube 48 has a right tapered shape and the closing member 50 has a spherical shape, the outer circumferential surface of the closing member 50 and the inner circumferential surface of the liquid injection port 42 contact each other at a section where the cross-section of the liquid injection port 42 gradually decreases along the first direction toward the inside of the tank.

[0236] That is, the slope of the inner circumferential surface of the liquid injection port 42 may be constant in predetermined sections further inward and further outward in the first direction than where the outer circumferential surface of the closing member 50 and the inner circumferential surface of the liquid injection port 42 contact each other.

[0237] Therefore, when the sealing and fixing material 52 loses its sealing and fixing force, a space for exhaust can be ensured between the closing member 50 and the inner peripheral surface of the liquid injection port 42 .

[0238] Since the closing member 50 is a spherical metal ball 50 and the circular tube 48 is tapered at a constant inclination, in a predetermined section of the perforated section that is closer to the inside in the first direction than the position where the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port contact each other, the rate at which the cross-section of the closing member 50 decreases toward the inside of the tank is greater than the rate at which the cross-section of the liquid injection port 42 decreases toward the inside of the tank.

[0239] Similarly, in a predetermined section of the perforated section that is further outward in the first direction than the position where the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port contact each other, the rate at which the cross-section of the closing member 50 decreases toward the interior of the tank is less than the rate at which the cross-section of the liquid injection port 42 decreases toward the interior of the tank.

[0240] Therefore, in predetermined sections of the perforated section that are further inward and further outward in the first direction than the position where the outer circumferential surface of the closing member 50 and the inner circumferential surface of the liquid injection port are in contact with each other so that the friction force does not take effect, the outer circumferential surface of the closing member 50 and the inner circumferential surface of the liquid injection port 42 may not be compressed against each other in the second direction.

[0241] Reference Fig.14 A position A3 where the outer peripheral surface of the closing member 50 and the inner peripheral surface of the liquid injection port 42 contact each other is disposed more inward in the first direction than a position A1 where the closing member 50 has the largest cross section.

[0242] Therefore, when a sealing and fixing material 52 to be described later loses its fixing force, the closing member 50 can be easily disengaged outwardly from the liquid injection port 42 in the first direction.

[0243] When the closing member 50 is placed in the liquid injection port 42 as described above, the sealing and fixing material 52 can be melted between the inner peripheral surface of the liquid injection port 42 and the outer peripheral surface of the closing member 50 at a position further outward in the first direction than the position A3 where the inner peripheral surfaces of the closing member 50 and the liquid injection port 42 contact each other.

[0244] Therefore, the seal section S may be provided at a position further outward in the first direction than the position A3 where the inner peripheral surface of the closing member 50 and the liquid injection port 42 contact each other.

[0245] When thermal runaway of the battery cell occurs, the solder 56 melts. As a result, the solder 56 cannot withstand the internal pressure of the can 10. Fig.16 As shown, the high-pressure gas inside the tank is discharged to the outside through the liquid injection port 42.

[0246] Furthermore, the sealing structure of the liquid injection port according to the second embodiment is different from that of the first embodiment in that an air hole 483 is provided in the circular tube 48 .

[0247] The inner end of the round tube 48 in the first direction extends to be inserted in the axial direction into the core hollow portion 29 of the electrode assembly 20. Here, the inner end of the round tube 48 in the first direction may be further extended inwardly in the can in the axial direction to a height h1 of the inner end that is lower than a height h2 required for impregnating the electrode assembly 20 with an electrolyte solution.

[0248] When the electrolyte solution is injected through the liquid injection port 42 in this state, the electrolyte solution fills up from the bottom portion 12 of the can 10. When the electrolyte solution is filled to the height h1 of the inner end, the space from the height h1 to the bottom surface of the cover 40 may be an air pocket space where air is trapped.

[0249] According to the present embodiment, an air hole 483 is provided in the circular tube 48. The air hole 483 may be provided at a height corresponding to or higher than the height h2 required for immersing the electrode assembly 20 in the electrolyte solution. Therefore, when the tank is filled with the electrolyte solution, the air in the air pocket is discharged through the air hole 483. The tank may be fully filled with the electrolyte solution up to the upper end of the electrode assembly 20, i.e., the required height h2, for smooth impregnation.

[0250] The air hole 483 is provided on the sealing section S. Therefore, even if the air hole 483 is not blocked separately after the electrolyte solution is injected, the air hole 483 is shielded together in the process of closing the liquid injection port with the sealing and fixing material 52. That is, after the injection of the electrolyte solution is completed and the ball 50 is inserted into the liquid injection port 42, the air hole 483 can be sealed together with the closing of the liquid injection port by the solder 56 that seals the inner circumferential surface of the liquid injection port 42 and the surface of the ball 50 without an additional process.

[0251] Obviously, the air hole 483 illustrated in the second embodiment can also be applied to the sealing structure of the liquid injection port according to the first embodiment. That is, in the first embodiment, when the air hole 483 is provided in the sealing section S where the synthetic resin layer 54 is pressed, similar to the second embodiment, the air hole 483 can be sealed in the process of closing the liquid injection port with the sealing and fixing material 52.

[0252] [Assembly of battery cells]

[0253] In the following, reference is made to Figures 17 to 29 , a method for manufacturing a battery cell using the above-described sealing structure of a liquid injection port according to a third embodiment and a structure of the battery cell will be described.

[0254] Fig.17 A cylindrical battery cell is shown.

[0255] The battery cell of the present embodiment may be, for example, a cylindrical battery cell having a shape factor ratio (defined as the diameter of the cylindrical battery cell divided by the height, ie, the ratio of the diameter Φ to the height H) greater than about 0.4.

[0256] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell to be applied to the pressure tester may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the value indicating the form factor, the first two digits indicate the diameter of the cell, the second two digits indicate the height of the cell, and the last digit 0 indicates that the cross section of the cell is circular.

[0257] The battery cell to be applied to the pressure tester may be a nearly cylindrical cell with a diameter of about 46 mm, a height of about 110 mm, and a shape factor ratio of 0.418.

[0258] A battery cell according to another embodiment may be a substantially cylindrical cell having a diameter of about 48 mm, a height of about 75 mm, and an aspect ratio of 0.640.

[0259] A battery cell according to yet another embodiment may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 110 mm, and an aspect ratio of 0.418.

[0260] A battery cell according to yet another embodiment may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 80 mm, and an aspect ratio of 0.600.

[0261] A battery cell according to another embodiment may be a substantially cylindrical cell having a diameter of about 46 mm, a height of about 80 mm, and an aspect ratio of 0.575.

[0262] The pressure tester of the present invention can obviously be applied to battery cells with a shape factor ratio of about 0.4 or less, such as 18650 cells, 21700 cells, etc. For 18650 cells, the diameter is about 18 mm, the height is about 65 mm, and the shape factor ratio is 0.277. For 21700 cells, the diameter is about 21 mm, the height is about 70 mm, and the shape factor ratio is 0.300.

[0263] The battery can 10 includes a cylindrical side wall portion 11 and a bottom portion 12 connected to one axial end of the side wall portion 11. Here, the term "bottom" is used because the bottom portion 12 is placed on the floor during the battery cell assembly process, with the open end of the battery can 10 facing upward. Figure 25 to Figure 29 As shown, it should be understood that in actual use of the battery cell, the bottom portion 12 can be placed on the top together with the first electrode terminal 13, such as Fig.17 shown.

[0264] The bottom portion 12 and the side wall portion 11 of the battery can 10 may be integrated into one body. For example, the battery can 10 may be manufactured by drawing a steel sheet or an aluminum sheet. The opposite ends of the side wall portion 11 in the axial direction that are not connected to the bottom portion 12 may form open ends.

[0265] A hole is formed in the central portion of the bottom portion 12, and the first electrode terminal 13 may be fitted and coupled to the hole. The first electrode terminal 13 may be riveted and fixed to the bottom portion 12 with the terminal gasket 14 interposed therebetween. The terminal gasket 14 is interposed between the first electrode terminal 13 and the bottom portion 12 to seal the inside and outside of the battery can 10, thereby preventing leakage of the electrolyte solution, and electrically insulating the first electrode terminal 13 from the bottom portion 12.

[0266] However, the connection method between the first electrode terminal 13 and the bottom portion 12 is not limited thereto. For example, when the structure can seal between the first electrode terminal 13 and the bottom portion 12 and electrically insulate the first electrode terminal 12 from the bottom portion 12, various fixing methods such as a bolt and nut fastening method, a glass sealing method, and a thermal bonding method using an insulating film such as a PP (polypropylene) material as a PP-MAH insulating gasket as a substrate are also applicable.

[0267] In an embodiment, the first electrode terminal 13 may have a first polarity, and the battery can 10 may have a second polarity. Therefore, both the bottom portion 12 of the battery can 10 and the sidewall portion 11 connected thereto may have the second polarity.

[0268] Therefore, both the first electrode terminal 13 and the second electrode terminal 15 may be disposed at one axial end of the battery can 10. Therefore, both the bus bar connected to the first electrode terminal 13 and the bus bar connected to the second electrode terminal 15 may be located at one axial end of the battery can 10, that is, at the upper portion of the battery can 10.

[0269] In one example, the first electrode terminal 13 may be a positive electrode terminal, and the second electrode terminal 15 may be a negative electrode terminal. Obviously, the reverse is also true.

[0270] The electrode assembly 20 is housed in the battery can 10. The electrode assembly 20 is manufactured by preparing a first electrode 21 having a predetermined width and extending in a length direction, a second electrode 22, and a separator 28, as shown in FIG. Fig.18 By sequentially stacking the first electrode 21, the separator 28, the second electrode 22 and the separator 28 to form a laminate; and the laminate is wound to have a Fig.19 and Fig. 20 The shape of the winding core type shown is wound around a mandrel.

[0271] The first electrode 21 may be an anode, and the second electrode 22 may be a cathode. Obviously, the reverse is also true.

[0272] The first electrode 21 and the second electrode 22 are manufactured in the form of a sheet. The electrode sheet is manufactured by coating an active material layer 24 on the surface of a metal foil 23. The electrode sheet includes a coated area 25 coated with the active material layer 24 and an uncoated area 26 not coated with the active material layer 24. The anode sheet is provided with the uncoated area 26 at one side in the width direction, and the cathode sheet is provided with the uncoated area 26 at the other side in the width direction.

[0273] The uncoated area 26 is exposed or protrudes from the laminate in the width direction. The uncoated area 26 itself serves as an electrode tab.

[0274] Notches may be formed at predetermined intervals in the uncoated region 26 to form a flag-shaped slotted joint 27 .

[0275] In this embodiment, the slotted joint 27 is shown in the shape of an equilateral trapezoid. However, the slotted joint 27 can have various shapes, such as semicircular, semi-elliptical, triangular, rectangular, parallelogram, etc.

[0276] Furthermore, in this embodiment, the slotted joints 27 having the same width arranged in the length direction are exemplified. However, the width of the slotted joint may be gradually widened from the core side toward the outer peripheral side.

[0277] Furthermore, in this embodiment, the height of the slotted joint 27 gradually increases from the core side toward the outer peripheral side. However, the height of the slotted joint may be constant or gradually decrease.

[0278] Furthermore, in this embodiment, the structure in which the slot joint 27 is removed in predetermined sections of the centripetal end and the distal end of the uncoated region 26 is illustrated. However, it is obvious that the slot joint may not be removed from the centripetal end of the uncoated region and may not be removed from the distal end of the uncoated region.

[0279] In the jellyroll type electrode assembly 20, the slotted joint 27 may be bent and flattened in the radial direction. The slotted joint 27 may be bent inward or outward in the radial direction. Fig.21 and Fig. 22 As shown, a structure in which the slotted joint 27 is bent inwardly in the radial direction is exemplified.

[0280] The slotted tabs 27 may be bent one by one in the process of forming the jellyroll type electrode assembly 20 by winding the laminated body. Alternatively, the slotted tabs 27 may be formed by bending all the slotted tabs 27 at once after the laminated body is wound to form the jellyroll type electrode assembly.

[0281] The slotted joint 27 of the first electrode 21 and the slotted joint 27 of the second electrode 22 bent and overlapped in the radial direction as described above can provide a plane substantially perpendicular to the axial direction at each of the two axial ends of the electrode assembly 20, such as Fig. 22 shown.

[0282] like Fig.23 As shown, the current collecting plate 31 may be joined to a substantially flat surface provided by bending the slotted joints 27 respectively exposed at both axial ends of the electrode assembly 20 .

[0283] The current collecting plate 31 may be manufactured by punching, trimming, piercing, and bending a metal sheet.

[0284] Reference Fig.23 The current collecting plate 31 includes a terminal connection portion 32 extending from the center in the radial direction, a ring portion 33 connecting the distal edge of the terminal connection portion 32 in the circumferential direction, and an electrode connection portion 34 extending centripetally from the ring portion 33 but not connected to the terminal connection portion 32. The center of the terminal connection portion 32 covers at least a portion of the core hollow portion of the electrode assembly 20.

[0285] Before the electrode assembly 20 is inserted into the battery can 10 , the electrode connecting part 34 is joined to the grooved tab 27 of the first electrode 21 of the electrode assembly 20 using a method such as laser welding.

[0286] Unlike this embodiment, for example, in the case where the battery cell has a different structure, the slotted joint 27 of the first electrode 21 or the current collecting plate 31 can be joined and electrically connected to the bottom portion 12 of the battery can 10 by welding. That is, it should be understood that the third embodiment is an example of a battery cell to which the sealing structure of the liquid injection port can be applied. In other words, it should be clearly understood that the sealing structure of the liquid injection port described above is not a technology that can be applied only to the structure of the battery cell disclosed in the third embodiment.

[0287] Reference Fig.24 , the current collecting plate may not be connected to the slotted joint 27 of the second electrode 22 of the electrode assembly 20. The slotted joint 27 may be joined and electrically connected to the cap portion 40 by direct welding or the like, which will be described later.

[0288] like Fig.25 and Fig.26 As shown, the electrode assembly 20 is accommodated in the battery can 10 with the current collecting plate 31 aligned to face the bottom portion 12 of the battery can 10. Here, the insulator 19 is interposed between the current collecting plate 31 and the bottom portion 12 of the battery can 10 to electrically insulate the first current collecting plate 31 from the bottom portion 12.

[0289] In addition, the terminal connection portion 32 of the current collecting plate 31 is joined to the first electrode terminal 13 fixed to the battery can 10 by resistance welding, ultrasonic welding or laser welding. The welding device for welding the current collecting plate 31 and the first electrode terminal 13 can perform welding by approaching the rear side of the center of the terminal connection portion 32 of the current collecting plate 31 from the other axial end of the electrode assembly 20 through the core hollow portion in the electrode assembly 20. Obviously, in addition to the above-mentioned welding method, the current collecting plate 31 and the first electrode terminal 13 can also be joined by brazing or soldering.

[0290] Reference Fig. 27 , with the electrode assembly 20 accommodated in the battery can 10 and the first electrode 21 connected to the first electrode terminal 13 , the slotted joint 27 of the second electrode 22 may be in direct contact with the cover 40 covering the open end of the battery can 10 .

[0291] In the case where the cover 40 is in close contact with the slotted joint 27, a scanning method may be used to irradiate the laser onto the surface of the cover 40 in a radial direction, such as Fig. 27 As shown, a welding portion W extending in the radial direction is formed. Obviously, the laser may not be irradiated onto the section of the scanning path where the liquid injection port is provided.

[0292] Therefore, the second electrode 22 is electrically connected through the slot joint 27 and the welded portion W of the cover 40. Obviously, the slot joint 27 and the cover 40 may be joined by a method other than welding, such as brazing or soldering.

[0293] Unlike this embodiment, the tab of the second electrode 22 may be engaged with and electrically connected to the inner peripheral surface of the side wall portion 11 of the battery can 10 .

[0294] Furthermore, unlike the above-described embodiment, the tap of the second electrode 22 may be joined to the cover 40 or the side wall portion 11 of the battery can 10 through a current collecting plate (not shown).

[0295] In addition, the tab of the second electrode 22 or the current collecting plate connected thereto may be joined and connected to both the inner circumferential surface of the sidewall portion 11 and the cover portion 40 .

[0296] In addition, a separate second electrode terminal may be provided at the cover portion 40 , and the tap of the second electrode 22 or the current collecting plate 31 may be connected to the second electrode terminal.

[0297] Return to reference Fig. 27 The edge of the cover 40 is joined to the open end of the side wall portion 11 of the battery can 10 for electrical connection, sealing and fixing. Therefore, the second electrode 22 can be electrically connected to the cover 40 and the battery can 10. The joint between the cover 40 and the battery can 10 can also be electrically connected and sealed using various methods such as welding, brazing and soldering.

[0298] Obviously, unlike this embodiment, the cover 40 may be fixed to the open end of the side wall portion 11 of the battery can 10 using a compression sealing method such as crimping. It should be understood that even with this structure, the sealing structure of the liquid injection port described above may be applied.

[0299] High temperature heat may be generated during welding of the lid 40 and the side wall portion 11. In the case where an electrolyte solution exists in the battery can 10 during welding, the electrolyte solution may be denatured or ignite due to the high temperature heat generated during welding.

[0300] Therefore, the electrolyte solution may be injected through the liquid injection port 42 after completing the processing of the welded portion W and the joint region M between which high-temperature heat is generated as described above.

[0301] like Fig.28 As shown, the liquid injection port 42 may be disposed at a position aligned with the core hollow portion 29 of the electrode assembly 20. In addition, the circular tube 48 defining the liquid injection port 42 may extend to the inside of the core hollow portion 29.

[0302] Therefore, since the circular tube 48 extends further downward than the upper end of the diaphragm surrounding the inner circumference of the core hollow portion 29, during the process of injecting the electrolyte solution through the liquid injection port 42, the electrolyte solution can be smoothly injected into the tank 10 without damaging the diaphragm surrounding the inner circumference of the core hollow portion 29 due to the electrolyte solution discharged through the lower end of the liquid injection port 42.

[0303] The injected electrolyte solution gradually fills the space inside the can 10 until the upper end of the can 10, and even when reaching the lower end of the circular tube 48, the air is smoothly discharged out of the can through the air holes 483, thereby smoothly impregnating the electrode assembly 20 without generating air pockets.

[0304] After the liquid injection is completed, Fig.28 As shown, the closure member 50 is inserted into the liquid injection port 42, and as shown in FIG. Fig.29 As shown, the sealing and fixing material 52 is used to seal and fix the closing member 50. At the same time, the sealing and fixing material 52 shields the air hole 483.

[0305] [Fourth Embodiment]

[0306] In the following, reference will be made to Figure 30 to Figure 34 The structure of the cover portion 40 applied to the battery cell of the fourth embodiment will be described in detail.

[0307] The cover 40 may be made of a circular metal sheet. The cover 40 has an electrode connection portion 41 that is recessed in a first direction corresponding to the axial direction of the battery cell 72. The electrode connection portion 41 may be formed by molding the metal sheet using a press.

[0308] The bottom surface of the electrode connecting part 41 is in close contact and engagement with the slotted joint 27 of the second electrode 22 of the electrode assembly 20. The electrode connecting part 41 manufactured by press-processing the metal sheet has a thickness slightly thinner than the thickness of the metal sheet. Therefore, when the laser is irradiated onto the surface of the electrode connecting part 41, the local heat generated by the laser can melt and engage the surface of the slotted joint 27 in contact with the electrode connecting part 41 and the bottom surface of the electrode connecting part 41.

[0309] A plurality of electrode connecting parts 41 may be provided. The fourth embodiment shows a structure in which four electrode connecting parts 41 are radially arranged at equal intervals of about 90 degrees in the circumferential direction. The electrode connecting part 41 extends in the radial direction, and a welding portion W of the slotted joint 27 for joining the electrode connecting part 41 to the second electrode 22 of the electrode assembly 20 may have a welding line shape formed in the radial direction to correspond to the extending direction of the electrode connecting part 41, such as Fig. 27 shown.

[0310] According to the present embodiment, a linear welding portion W extending in the radial direction is formed for each of the plurality of electrode connecting portions 41 .

[0311] When the battery can 10 is placed with its cover 40 facing the floor, the cover 40 provides a base surface 44 in contact with the floor. The base surface 44 is provided at a higher position than the electrode connecting portion 41 and between two adjacent electrode connecting portions 41 in the circumferential direction.

[0312] Therefore, in the case where the electrode connecting portion 41 and the slotted joint 27 are brought into close contact with each other by pressing the base surfaces 44 on both sides of the electrode connecting portion 41 in the circumferential direction with a jig, it is possible to Fig. 27 The electrode connection part 41 and the slot joint 27 are welded by irradiating laser light onto the surface of the electrode connection part 41. As a result, the electrode connection part 41 is in close contact with the slot joint 27 along the length direction of the welding line due to the pressure of the clamp on the electrode connection part 41 on both sides of the welding line, so that welding can be performed reliably.

[0313] A pair of electrode connecting portions 41 facing each other with respect to the center of the cover portion 40 are arranged on a straight line passing through the center of the cover portion 40. Therefore, a welding line of two electrode connecting portions 41 arranged in a straight line can be formed by only one movement of the laser welding machine. For example, assuming that the first electrode connecting portion, the second electrode connecting portion, the third electrode connecting portion, and the fourth electrode connecting portion are sequentially arranged in the circumferential direction in the cover portion 40 of the fourth embodiment, the first electrode connecting portion and the third electrode connecting portion can be welded at one time, and the second electrode connecting portion and the fourth electrode connecting portion can be welded at one time.

[0314] In addition, according to the present embodiment, even when the base surfaces 44 on both sides of the first electrode connecting portion and the third electrode connecting portion arranged in a row relative to the center of the cover portion 40 are pressed by a clamp, due to the larger secondary moment of inertia formed by the concave shapes of the second electrode connecting portion and the fourth electrode connecting portion, the cover portion 40 can behave as a rigid body without warping or bending due to the pressure of the clamp.

[0315] In the present embodiment, by arranging the four electrode connecting portions 41 as described above, all the four electrode connecting portions 41 can be welded using two laser scanning traces.

[0316] When the number of processed electrode connecting parts 41 is too large, the strength of the cover part 40 made of the metal sheet may be weakened. In addition, when only two or three electrode connecting parts 41 are formed, it is difficult to configure a cross section for ensuring sufficient secondary moment of inertia in the circumferential direction.

[0317] When the four electrode connection parts 41 on the cover 40 are arranged to form a "+" shape as shown in the figure, the welding process can be accurately and easily performed, and the warpage resistance and bending resistance of the cover 40 can also be ensured, and the strength of the cover 40 can be prevented from being weakened due to the molding process. That is, although the cover 40 serves as a current collecting plate, it is preferred to maintain the strength of the original function for closing the open end of the battery can 10.

[0318] The outer side edge of the cover portion 40 in the radial direction has a shape that can be joined to the other axial end of the side wall portion 11 of the battery can 10. Therefore, preferably, the outer side edge of the cover portion 40 in the radial direction is provided with a circular outer peripheral surface or inner surface.

[0319] The edge of the cover portion 40 according to the fourth embodiment has a circular inner surface, and the electrode connecting portion 41 is recessed further inward in the axial direction from the inner side in the radial direction than the circular inner surface of the edge. Fig. 27 As shown, the circular inner surface of the cover portion 40 contacts the axial end surface of the side wall portion 11 of the battery can 10 and can form a joint area M welded by laser irradiated from the outer peripheral side of the battery can 10 toward the inside in the radial direction.

[0320] Here, the outer edge of the recessed portion for forming the electrode connecting portion 41 in the radial direction constitutes an outer wall. The outer wall may constitute a press-fit outer wall 45, the outer diameter of which corresponds to the inner diameter of the battery can 10. As a result, when the cover 40 is assembled to the battery can 10, as shown in FIG. Fig. 27 As shown, each of the press-fit outer walls 45 of the plurality of electrode connecting parts 41 is connected to the inner circumferential surface of the battery can 10 and is press-fitted into the battery can 10 to guide the alignment of the cover 40 relative to the center of the battery can 10 .

[0321] According to the fourth embodiment, since the four press-fitting outer walls 45 are evenly arranged in the circumferential direction and contact the battery can 10 at certain portions of the circumference of the inner circumferential surface, the cover 40 can be easily press-fitted into the battery can 10 without requiring a high press-fitting force for the cover 40.

[0322] As described above, the cover portion 40 according to the present embodiment is advantageous in that the manufacture thereof is facilitated because the press-fit outer wall 45 is molded together when the electrode connecting portion 41 is molded.

[0323] In addition, according to the structure of the cover 40, since the laser used to weld the cover 40 and the battery can 10 is irradiated in the radial direction, even when some parts of the inner surface of the edge of the cover 40 and the end of the side wall portion 11 of the battery can 10 are not in close contact with each other due to accidental errors, there is no risk of the laser being directly irradiated into the battery can 10 and damaging the electrode assembly 20.

[0324] According to the fourth embodiment, since the base surface 44 of the cover portion 40 is located further outward than the joint region M between the cover portion 40 and the battery can 10 in the axial direction, even when Fig.29 When the battery can 10 is turned over and stands upright in the vertical direction, the joint area M does not directly contact the ground, which helps to protect the joint area M.

[0325] By applying the above-mentioned cover 40, it is not necessary to use a current collecting plate to electrically connect the joint of the second electrode 22 to the battery can 10, thereby reducing the number of parts and assembly man-hours, and ensuring a larger internal volume to improve energy density. In addition, the cover 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 through the welding portion W extending in the radial direction, so that the current path is evenly distributed, thereby greatly reducing the internal resistance.

[0326] The liquid injection port 42 is provided at the central portion of the cover 40. The liquid injection port 42 may be provided on the bottom surface of the cover 40, that is, on the electrode connection part 41 of the cover 40.

[0327] The liquid injection port 42 provided at the center of the cover portion 40 may be a passage through which equipment for welding the first electrode terminal 13 and the current collecting plate 31 of the first electrode 21 enters and exits. Figure 25 to Figure 29 Unlike the above assembly sequence shown in , when the electrode assembly 20 is placed inside the battery can, the cover 40 can be inserted into the battery can 10 with the cover 40 engaged to the tab of the second electrode 22 of the electrode assembly 20, as shown in FIG. Fig.35 shown.

[0328] That is, Fig.35 As shown, the electrode assembly 20 can be housed in the battery can 10 with the current collecting plate 31 joined to the joint of the first electrode 21 of the electrode assembly 20 and the cover 40 joined to the joint of the second electrode 22. In addition, welding between the current collecting plate 31 and the first electrode terminal 13 can be performed through the liquid injection port 42 of the cover 40 and the core hollow portion 29 of the electrode assembly 20.

[0329] [Battery cell manufacturing method]

[0330] Since the cover 40 according to the fourth embodiment described above serves as a current collecting plate for the second electrode and also has the original function of the cover, the cover 40 according to the fourth embodiment is different from a conventional battery cell provided with a current collecting plate for the second electrode in its manufacturing method.

[0331] Furthermore, since the cap 40 is provided with the liquid injection port 42 and the liquid injection port 42 may be used as a passage for a bonding process of the current collecting plate 31 and the first electrode terminal 13 , a manufacturing method of the battery cell may be more diversified.

[0332] First, refer to Fig.36 A method for manufacturing a battery cell according to a fifth embodiment is described. The fifth embodiment corresponds to Figure 25 to Figure 29 A method for manufacturing a battery cell.

[0333] The manufacturing method includes: preparing a battery can 10 having a first electrode terminal 13 fixed thereto; and preparing an electrode assembly 20 having a first electrode 21 and a second electrode 22. Here, at one axial end of the electrode assembly 20, the first electrode 21 and the current collecting plate 31 may be joined and connected.

[0334] Thereafter, the electrode assembly 20 is inserted into the battery can 10 with the current collecting plate facing the bottom portion 12 of the battery can 10, and the current collecting plate 31 of the electrode assembly 20 is joined to the first electrode terminal 13 fixed to the bottom portion 12 of the battery can 10 by a method such as welding.

[0335] Thereafter, the open end of the battery can 10 is covered by the cover 40. Here, preferably, the electrode connecting portion 41 of the cover 40 and the joint of the second electrode 22 of the electrode assembly 20, which are in close contact with each other, are joined, and then the periphery of the open end of the battery can 10 and the edge of the cover 40 are joined.

[0336] Thereafter, the electrolyte solution is injected into the battery can 10 through the liquid injection port 42 of the lid portion 40 .

[0337] Finally, by applying the above-described sealing structure of the liquid injection port, the liquid injection port 42 of the battery can 10 is closed and sealed using the closing member 50 and the sealing and fixing material 52 .

[0338] According to this manufacturing method, a separate current collecting plate bonding operation for the second electrode 22 is not required, and the cap 40 and the battery can 10 can be bonded before injecting the electrolyte solution into the battery can 10 , thus preventing the electrolyte solution from being affected by bonding heat.

[0339] Hereinafter, the manufacturing method disclosed in FIG. 41 will be described.

[0340] The manufacturing method includes: preparing a battery can 10 having a first electrode terminal 13 fixed thereto; and preparing an electrode assembly 20 having a first electrode 21 and a second electrode 22. Here, at one axial end of the electrode assembly 20, the first electrode 21 and the current collecting plate 31 may be joined and connected. In addition, the electrode connecting portion 41 of the cover portion 40 and the joint of the second electrode 22 may be connected to the other axial end of the electrode assembly 20.

[0341] That is, before the electrode assembly is housed in the battery can, the cap part 40 may be coupled to the second electrode of the electrode assembly.

[0342] Thereafter, the electrode assembly 20 is inserted into the battery can 10 with the current collecting plate facing the bottom portion 12 of the battery can 10. In this process, the cap portion 40 covers the open end of the battery can 10.

[0343] Thereafter, the current collecting plate 31 of the electrode assembly 20 is joined to the first electrode terminal 13 fixed to the bottom portion 12 of the battery can 10 by a method such as welding, and then the periphery of the opening end of the battery can 10 and the edge of the cover 40 are joined.

[0344] Thereafter, the electrolyte solution is injected into the battery can 10 through the liquid injection port 42 of the lid portion 40 .

[0345] Finally, by applying the above-described sealing structure of the liquid injection port, the liquid injection port 42 of the battery can 10 is closed and sealed using the closing member 50 and the sealing and fixing material 52 .

[0346] According to this manufacturing method, there is no need for a joining operation of a separate current collecting plate for the second electrode 22, and since the joining of the cover 40 and the second electrode 22 as well as the joining of the cover 40 and the battery can 10 can be performed before the electrolyte solution is injected into the battery can 10, the electrolyte solution is prevented from being affected by the joining heat, and the assembly equipment can be further simplified by first integrating the cover 40 into the electrode assembly 20 instead of managing the cover 40 separately.

[0347] As such, when a battery cell is manufactured by applying the cap portion 40 provided with the liquid injection port 42 axially aligned with the core hollow portion 29 of the electrode assembly 20 , the manufacturing method of the battery cell can be more diversified.

[0348] Furthermore, since neither strong pressure nor high temperature heat is applied to the cover 40 when sealing the liquid injection port 42, there is no risk that the internal structure of the battery can 10 is damaged, denatured, or ignites due to heat.

[0349] [Battery pack and vehicle]

[0350] Reference Fig.38 The battery cell 72 using the sealing structure of the liquid injection port and / or manufactured by the manufacturing method described above can be accommodated in the housing 71 of the battery pack 70. The battery pack 70 can be constructed using a battery module as an intermediate form of assembly, or directly constructed without a battery module as shown in the figure.

[0351] Since the battery cell 72 itself has a large volume, there is no particular difficulty in implementing the battery pack 70 even without using the intermediate structure of the so-called battery module. In addition, since the second electrode is connected through the cover portion, the battery cell 72 has a lower internal resistance and a higher energy density. Therefore, the energy density of the battery pack 70 can be realized to be higher.

[0352] The battery pack 70 having such an increased energy density can store the same amount of energy with a reduced volume and weight. Therefore, when the battery pack 70 using the battery cells 72 is installed in a vehicle such as the vehicle 80 shown in FIG. 40 that uses electricity as an energy source, the driving range of the vehicle relative to energy can be further extended.

[0353] It should be understood that the described embodiments are illustrative in all aspects and not restrictive, and the scope of the present invention will be indicated by the appended claims rather than by the specific embodiments described. And the meaning and scope of the claims to be described, as well as all changes and modifications derived from equivalent concepts should be interpreted as being included within the scope of the present invention.

[0354] Although the present invention has been described with reference to the accompanying drawings illustrated, it is to be understood that the present invention is not limited to the embodiments and drawings disclosed in this specification, and those skilled in the art will understand that various modifications may be made without departing from the scope and concept of the present invention. In addition, although the operational effects of the configuration according to the present invention are not explicitly described when describing the embodiments of the present invention, it should be understood that predictable effects will also be recognized by the configuration.

Claims

1. A battery cell, comprising: a tank (10) having an open end at one end; an electrode assembly (20), the electrode assembly (20) being accommodated in the can (10); a cover (40), the cover (40) covering the open end of the can (10); a liquid injection port (42), wherein the liquid injection port (42) is disposed on the tank (10) or the cover (40); a closing member (50) inserted into the liquid injection port (42); and a sealing and fixing material (52) for fixing a closing member (50) inserted into the liquid injection port (42) within the liquid injection port (42), wherein: The liquid injection port (42) has a perforated section extending in a first direction across the exterior and interior of the battery cell, and has a cross section defined by an intersection of an imaginary plane extending in a second direction intersecting the first direction and an inner peripheral surface of the liquid injection port (42), The closing member (50) extends in the first direction and has a cross section defined by an intersection of the imaginary plane extending in the second direction and an outer peripheral surface of the closing member (50), At least a portion of the closing member (50) in the first direction is disposed within the perforated section of the liquid injection port (42), The sealing and fixing material (52) is interposed between the inner peripheral surface of the liquid injection port (42) and the outer peripheral surface of the closing member (50) in the second direction, The sealing and fixing material (52) seals the space between the inner peripheral surface of the liquid injection port (42) and the outer peripheral surface of the closing member (50) to provide a sealing section corresponding to at least a portion of the perforated section along the first direction, and fixes the closing member (50) in the liquid injection port (42), and The melting point of the sealing and fixing material (52) is lower than the melting point of the lid portion (40) or the tank (10) provided with the liquid injection port (42) and the melting point of the closing member (50).

2. The battery cell according to claim 1, wherein: The minimum cross-section of the liquid injection port (42) is smaller than the maximum cross-section of the closing member (50), and The minimum cross-section of the liquid injection port (42) is arranged more inwardly than the sealing section in the first direction.

3. The battery cell according to claim 1, wherein: The liquid injection port (42) is defined by the inner peripheral surface of a circular tube (48) extending from the tank (10) or the cover (40) along the first direction.

4. The battery cell according to claim 3, wherein: The inner end of the circular tube (48) in the first direction extends in the axial direction to be inserted into the core hollow portion (29) of the electrode assembly (20).

5. The battery cell according to claim 4, wherein: The circular tube (48) is provided with an air hole (483) for discharging air in the tank (10) when the electrolyte solution is injected through the liquid injection port, and The air hole (483) is arranged in the sealing section.

6. The battery cell according to claim 1, wherein: The outer peripheral surface of the sealing member (50) does not directly contact the inner peripheral surface of the liquid injection port (42).

7. The battery cell according to claim 6, wherein: The sealing and fixing material (52) is arranged to be fixed integrally to the outer peripheral surface of the closing member (50).

8. The battery cell according to claim 7, wherein: The sealing and fixing material (52) includes a synthetic resin layer (54) coated on the surface of the closing member (50).

9. The battery cell according to claim 6, wherein: The elastic modulus of the sealing and fixing material (52) is lower than the elastic modulus of the closing member (50).

10. The battery cell according to claim 9, wherein: The closure member (50) comprises a metal material.

11. The battery cell according to claim 9, wherein: The sealing and fixing material (52) has a cross section defined by an intersection of an imaginary plane extending in the second direction and an outer peripheral surface of the sealing and fixing material (52), and The cross-section of the sealing and fixing material (52) at the sealing section is larger than the cross-section of the liquid injection port (42) at the sealing section, so that it is compressed inwardly along the second direction through the inner circumferential surface of the liquid injection port (42) to correspond to the cross-section of the liquid injection port (42).

12. The battery cell according to claim 11, wherein: The cross-section of the sealing and fixing material (52) at a position further inward than the sealing section along the first direction gradually decreases toward the inside of the tank (10) in the first direction.

13. The battery cell according to claim 12, wherein: The inner end of the sealing and fixing material (52) in the first direction covers the closing member (50) in the first direction.

14. The battery cell according to claim 11, wherein: The cross section of the closing member (50) at a position further inward than the sealing section along the first direction gradually becomes smaller toward the inside of the can (10) in the first direction.

15. The battery cell according to claim 6, wherein: The closure member (50) comprises a ball (50), and The sealing and fixing material (52) is integrally coated on the ball (50).

16. The battery cell according to claim 15, wherein: The inner peripheral surface of the liquid injection port (42) extends parallel to the first direction in the sealing section.

17. The battery cell according to claim 1, wherein: The outer peripheral surface of the closing member (50) contacts the inner peripheral surface of the liquid injection port (42).

18. The battery cell according to claim 17, wherein: The outer peripheral surface of the closing member (50) and the inner peripheral surface of the liquid injection port (42) are in line contact in the circumferential direction.

19. The battery cell according to claim 17, wherein: The outer peripheral surface of the closing member (50) and the inner peripheral surface of the liquid injection port (42) contact each other at a section where the cross section of the liquid injection port (42) gradually decreases toward the inside of the tank (10) along the first direction.

20. The battery cell according to claim 19, wherein: At a predetermined portion that is further inward and further outward in the first direction than the position where the outer peripheral surface of the closing member (50) and the inner peripheral surface of the liquid injection port (42) contact each other, the radius of the cross-section defining the liquid injection port (42) decreases at a constant rate toward the interior of the tank (10) in the first direction.

21. The battery cell according to claim 17, wherein: The outer peripheral surface of the closing member (50) and the inner peripheral surface of the liquid injection port (42) contact each other at a section where the cross section of the closing member (50) gradually decreases toward the inside of the tank (10) along the first direction.

22. The battery cell according to claim 17, wherein: In a predetermined portion that is closer to the inside in the first direction than the position where the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port contact each other, the rate at which the cross-section of the closing member (50) decreases in the first direction toward the interior of the tank is greater than the rate at which the cross-section of the liquid injection port (42) decreases in the first direction toward the interior of the tank.

23. The battery cell according to claim 17, wherein: In a predetermined portion which is further outward in the first direction than the position where the outer peripheral surface of the closing member and the inner peripheral surface of the liquid injection port contact each other, a rate at which the cross-section of the closing member (50) decreases in the first direction toward the interior of the tank is greater than a rate at which the cross-section of the liquid injection port (42) decreases in the first direction toward the interior of the tank.

24. The battery cell according to claim 17, wherein: The position where the outer peripheral surface of the closing member (50) and the inner peripheral surface of the liquid injection port (42) contact each other is located further inward in the first direction than the position where the closing member (50) has the largest cross section.

25. The battery cell according to claim 17, wherein: The sealing section is disposed further outward in the first direction than a position where the outer peripheral surface of the closing member (50) and the inner peripheral surface of the liquid injection port (42) contact each other.

26. The battery cell according to claim 25, wherein: The closure member (50) comprises a metal material, and The sealing and fixing material (52) includes solder (56), and when the outer peripheral surface of the closing member (50) contacts the inner peripheral surface of the liquid injection port (42), the solder (56) is filled between the outer peripheral surface of the closing member (50) and the inner peripheral surface of the liquid injection port (42).

27. The battery cell according to claim 26, wherein: The closure member (50) comprises a ball (50).

28. The battery cell according to claim 1, wherein: The liquid injection port (42) is provided at the cover portion (40), and The edge of the open end of the can (10) is joined to the edge of the cover (40) by thermal bonding.

29. The battery cell according to claim 28, wherein: The thermal bonding of the can (10) and the cover (40) includes a process selected from welding, brazing and soldering.

30. The battery cell according to claim 28, wherein: The electrode assembly (20) comprises a first electrode (21) and a second electrode (22), and a joint of the first electrode (21) and a joint of the second electrode (22) are respectively arranged at two axial ends of the electrode assembly (20), A first electrode terminal (13) electrically insulated from and fixed to a bottom portion (12) disposed on an opposite side of the open end of the can (10) in the axial direction is installed at the bottom portion (12), and 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 joint of the first electrode (21).

31. The battery cell according to claim 28, wherein: The electrode assembly (20) comprises a first electrode (21) and a second electrode (22), and a joint of the first electrode (21) and a joint of the second electrode (22) are respectively arranged at two axial ends of the electrode assembly (20), and The cover portion (40) includes an electrode connecting portion (41) joined to a joint of the second electrode (22) of the electrode assembly (20) by thermal bonding.

32. The battery cell according to claim 31, wherein: The thermal bonding of the joint of the cover (40) and the second electrode (22) includes a process selected from welding, brazing and soldering.

33. The battery cell according to claim 31, wherein: The liquid injection port (42) is provided at the central portion of the cover portion (40), and The electrode connecting portion (41) extends radially around the liquid injection port (42).

34. The battery cell according to claim 31, wherein: The cover portion (40) has a base surface (44) extending outward from the electrode connecting portion (41) in an axial direction.

35. A method for manufacturing a battery cell, the method comprising the following steps: A can preparation step: preparing a can (10), the can (10) having a side wall portion (11), a bottom portion (12) connected to one axial end of the side wall portion (11), and an open end provided at the other axial end of the side wall portion (11); and sealing, insulating and fixing a first electrode terminal (13) at the center of the bottom portion (12); Electrode assembly preparation step: preparing an electrode assembly (20), wherein the electrode assembly (20) is provided with a first electrode (21) and a second electrode (22), wherein a joint of the first electrode (21) and a joint of the second electrode (22) are respectively provided at two axial ends of the electrode assembly (20); Cover preparation step: preparing a cover (40) provided with a liquid injection port (42); a first electrode terminal connecting step: after the can preparation step and the electrode assembly preparation step, accommodating the electrode assembly (20) in the can (10) in a manner that the joint of the first electrode (21) faces the bottom portion (12) of the can (10), and connecting the joint of the first electrode (21) to the first electrode terminal (13); A second electrode connecting step: after the electrode assembly preparation step and the cover preparation step, connecting the cover (40) to the connector of the second electrode (22); a cover fixing step: after the first electrode terminal connecting step, fixing the cover (40) to the can (10); a liquid injection step of injecting an electrolyte solution into the can (10) after the first electrode terminal connection step, the second electrode connection step, and the cover fixing step; and Liquid injection port sealing step: after the liquid injection step and the cover portion preparation step, inserting a sealing member (50) into the liquid injection port (42); and sealing a space between an inner peripheral surface of the liquid injection port (42) and an outer peripheral surface of the sealing member (50) with a sealing and fixing material (52) having a melting point lower than the melting point of the cover portion (40) provided with the liquid injection port (42) and the melting point of the sealing member (50), and sealing and fixing the sealing member (50) in the liquid injection port (42).

36. The method for manufacturing a battery cell according to claim 35, wherein: The liquid injection port sealing step is performed by the following operation: the sealing member (50) coated with the sealing and fixing material (52) on the surface is pressed into the liquid injection port (42) to elastically compress the sealing and fixing material (52) between the outer peripheral surface of the sealing member (50) and the inner peripheral surface of the liquid injection port (42).

37. The method for manufacturing a battery cell according to claim 35, wherein: The liquid injection port closing step is performed by the following operation: when the closing member (50) is inserted into the liquid injection port (42) and the outer peripheral surface of the closing member (50) is in line contact with the inner peripheral surface of the liquid injection port (42), the outer peripheral surface of the closing member (50) is soldered to the inner peripheral surface of the liquid injection port (42) using the sealing and fixing material (52).

38. A battery pack comprising a battery cell according to any one of claims 1 to 34.

39. A vehicle comprising the battery pack according to claim 38.

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