Method for manufacturing electrode assembly, battery cell manufactured using same, and system for manufacturing electrode assembly

Abstract

Provided is a method for manufacturing electrode assembly, the method comprising: a preparation step of aligning electrode tabs of one or more first electrode plates; a cooling step of cooling the electrode tabs; and a connecting step of coupling the cooled electrode tabs and lead tabs to each other.

Description

Method for manufacturing an electrode assembly, battery cell manufactured using the same, and electrode assembly manufacturing system

[0001] The present invention relates to a method for manufacturing an electrode assembly, a battery cell manufactured using the same, and an electrode assembly manufacturing system.

[0002] Unlike primary batteries, secondary batteries can be recharged and discharged, making them suitable for a wide range of applications, including digital cameras, mobile phones, laptops, hybrid vehicles, and electric vehicles. Secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-hydrogen batteries, with lithium-ion batteries becoming increasingly popular.

[0003] In the case of conventional lithium ion batteries, copper or aluminum foil, etc., is used as a metal current collector for the negative or positive electrode, and a negative or positive electrode active material is laminated on both sides to produce the negative or positive electrode.

[0004] In contrast, in the case of next-generation batteries such as lithium-sulfur batteries (Li-S batteries) or lithium metal batteries (Li-Metal batteries), the negative electrode may be made of lithium metal itself. In this case, the lithium metal that makes up the negative electrode plate has lower mechanical strength than the metal current collector of a conventional negative electrode, so there is a concern that it may be easily deformed or seized during the process of manufacturing the negative electrode. In particular, the electrode tab of the negative electrode made of lithium metal may be pressed and spread out by pressure during the welding process with the lead tab, resulting in insufficient bonding strength, interference with other components of the battery cell, and easy seizing in the welder.

[0005] Accordingly, a manufacturing method capable of increasing the ease of bonding and bonding strength of the electrode tab and lead tab of a negative electrode made of lithium metal is required.

[0006] The present invention has been devised to solve at least some of the problems of the above-mentioned prior art, and provides a method for manufacturing an electrode assembly and an electrode assembly manufacturing system capable of implementing excellent bonding quality and bonding ease between an electrode tab and a lead tab.

[0007] In addition, an object of the present invention is to provide a method for manufacturing an electrode assembly and an electrode assembly manufacturing system capable of preventing lithium sticking during the bonding process between an electrode tab and a lead tab.

[0008] In addition, it is an object of the present invention to provide a method for manufacturing an electrode assembly and an electrode assembly manufacturing system in which a manufacturing process can be performed in a state in which an electrode tab is cooled and hardened to increase mechanical rigidity.

[0009] To achieve the above purpose, in embodiments, a method for manufacturing an electrode assembly is provided, including a preparatory step of aligning electrode tabs of one or more first electrode plates; a cooling step of cooling the electrode tabs; and a connecting step of joining the cooled electrode tabs and lead tabs to each other.

[0010] In a method for manufacturing an electrode assembly according to embodiments, the electrode tabs of one or more first electrode plates may be made of lithium or an alloy including lithium.

[0011] In embodiments, in the cooling step, the electrode tab may be cooled in a pressurized state by the cooling device.

[0012] In a method for manufacturing an electrode assembly according to embodiments, the cooling device includes a first press portion and a second press portion that move relative to each other in a direction toward each other to press the electrode tab, and at least one of the first press portion and the second press portion may include a cooling channel through which a coolant flows.

[0013] In a method for manufacturing an electrode assembly according to embodiments, a coolant flowing through a cooling channel is liquid nitrogen.

[0014] In embodiments, in the preparation step, one or more first electrode plates are alternately stacked with one or more second electrode plates with a separator therebetween, and one or more second electrode plates may have a polarity opposite to that of one or more first electrode plates.

[0015] In embodiments, an electrode tab bundle is formed in which electrode tabs of one or more first electrode plates are laminated in the preparation step, and the electrode tab bundle can be cooled in the cooling step.

[0016] In a method for manufacturing an electrode assembly according to embodiments, one or more first electrode plates may be made of lithium or an alloy containing lithium.

[0017] In embodiments, the connecting step may include a first connecting step of aligning the cooled electrode tab and the lead tab on a connecting device; and a second connecting step of joining the electrode tab and the lead tab by the connecting device.

[0018] In embodiments, the temperature of the electrode tab in the first connection step may be 0°C or less.

[0019] In embodiments, the electrode tab and the lead tab may be joined via ultrasonic welding in the second connection step.

[0020] A battery cell is provided, including an electrode assembly manufactured by a method for manufacturing an electrode assembly according to embodiments; and a case enclosing the electrode assembly.

[0021] In embodiments, an electrode assembly manufacturing system is provided, including a laminating device aligning one or more first electrode plates and one or more second electrode plates having opposite polarities; a cooling device cooling an electrode tab of one or more first electrode plates; and a connecting device connecting the cooled electrode tab and the lead tab.

[0022] In embodiments, the cooling device includes a first press portion and a second press portion that move relative to each other in a direction toward each other to press the electrode tab, and at least one of the first press portion and the second press portion may include a cooling channel through which a refrigerant flows.

[0023] In embodiments, the connecting device may be configured to ultrasonically weld the cooled electrode tab and the lead tab.

[0024] According to embodiments, an electrode assembly manufacturing method and an electrode assembly manufacturing system capable of implementing excellent bonding quality and bonding ease between an electrode tab and a lead tab can be implemented.

[0025] In addition, according to embodiments, a method for manufacturing an electrode assembly and a system for manufacturing an electrode assembly can be provided that can prevent lithium sticking during the bonding process between an electrode tab and a lead tab.

[0026] In addition, a method for manufacturing an electrode assembly and an electrode assembly manufacturing system can be provided in which a manufacturing process can be performed in a state in which the electrode tab is cooled and hardened through a cooling process to increase mechanical rigidity.

[0027] Figure 1 is an exploded perspective view of a battery cell.

[0028] Figure 2 illustrates an example of the configuration of an electrode assembly.

[0029] Figure 3 is a flowchart showing a method for manufacturing an electrode assembly according to embodiments.

[0030] Figure 4 shows an exemplary configuration of an electrode assembly manufacturing system according to embodiments.

[0031] Figure 5 shows an exemplary configuration of a cooling device.

[0032] Fig. 6 is a reference drawing exemplarily showing an appearance in which at least a portion of an electrode tab is cooled by a cooling device.

[0033] Figure 7 shows an exemplary configuration of a connecting device.

[0034] Before going into the detailed description of the present invention, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted with meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term in order to explain his own invention in the best way. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical idea of ​​the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of this application.

[0035] The same reference numbers or symbols used in each drawing attached to this specification represent parts or components that perform substantially the same functions. For convenience of explanation and understanding, the same reference numbers or symbols may be used in different embodiments. In other words, even if components with the same reference numbers are depicted in multiple drawings, they do not necessarily represent a single embodiment.

[0036] In the following description, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as "comprises" or "comprises" should be understood to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0037] In addition, in the description below, expressions such as top, upper, lower, lower, side, front, and rear are expressed based on the direction shown in the drawing, and it is noted in advance that they may be expressed differently if the direction of the object in question changes.

[0038] Additionally, terms including ordinal numbers, such as "first," "second," etc., may be used in this specification and claims to distinguish between components. These ordinal numbers are used to distinguish identical or similar components from each other, and the use of these ordinal numbers should not be interpreted in a limited manner. For example, components associated with these ordinals should not be interpreted in a restricted manner, such as in the order of use or arrangement, based on their numbers. If necessary, each ordinal number may be used interchangeably.

[0039] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. However, the spirit of the present invention is not limited to the presented embodiments. For example, those skilled in the art who understand the spirit of the present invention may propose other embodiments within the spirit of the present invention by adding, modifying, or deleting components, etc., but such embodiments will also be considered to be within the spirit of the present invention. The shapes and sizes of elements in the drawings may be exaggerated for clarity.

[0040] First, referring to FIGS. 1 and 2, the configuration of a battery cell (1) according to embodiments will be described.

[0041] Figure 1 is an exploded perspective view of a battery cell (1).

[0042] Figure 2 exemplarily shows the configuration of an electrode assembly (10).

[0043] Referring to FIG. 1, a battery cell (1) according to an embodiment may include an electrode assembly (10) in which a plurality of electrode plates are stacked, a case (500) in which the electrode assembly (10) is accommodated, and a lead tab (400) electrically connected to the electrode assembly (10) and having a portion exposed to the outside of the case (500).

[0044] The case (500) may include an electrode receiving portion (501) in which an electrode assembly (10) is received, and a sealing portion (502) arranged along the edge of the electrode receiving portion (501). The electrode receiving portion (501) is formed by joining an upper case (520) and a lower case (510) vertically, and may have an internal space in which the electrode assembly (10) is received. The sealing portion (502) is formed by pressing or heat-welding the edges of the upper case (520) and the lower case (510) along the edge of the electrode receiving portion (501), thereby preventing foreign substances or moisture from outside the case (500) from entering the electrode assembly (10) received inside the electrode receiving portion (501).

[0045] The case (500) may be a pouch-shaped case made of a flexible material. For example, the case (500) may be made of an aluminum laminate sheet. However, the case (500) of the battery cell (1) according to the embodiments may also be made of a can-shaped (or square) case or a cylindrical case made of a metal material such as aluminum, in addition to the above-described pouch-shaped case.

[0046] Referring to FIG. 2, the electrode assembly (10) may have a structure in which a plurality of first electrode plates (100) and a plurality of second electrode plates (200) having opposite polarities are laminated with a separator (300) therebetween. However, those illustrated in FIG. 2 are only a part of the first electrode plates (100), the second electrode plates (200), and the separators (300) included in the electrode assembly (10), and the actual electrode assembly (10) may have a greater number of first electrode plates (100), second electrode plates (200), and separators (300) than those illustrated in FIG. 2.

[0047] The separator (300) may be interposed between the first electrode plate (100) and the second electrode plate (200) to prevent electrical short circuits between the first electrode plate (100) and the second electrode plate (200) and to be configured to be impregnated with an electrolyte so that ions can pass through. The separator (300) may be formed of a porous polymer film or a porous non-woven fabric. However, in addition to the above materials, any material commonly used in lithium secondary batteries may be used without special restrictions as long as it is used.

[0048] The first electrode plate (100) and the second electrode plate (200) may each be provided with electrode tabs (120, 220). In the following description, the electrode tab of the first electrode plate (100) is defined as the first electrode tab (120), and the electrode tab of the second electrode plate (200) is defined as the second electrode tab (220).

[0049] In the electrode assembly (10), a plurality of first electrode tabs (120) and second electrode tabs (220) may be provided. The plurality of electrode tabs (120, 220) may be grouped together with the same polarity to form an electrode tab bundle. A lead tab (400) serving as a terminal in a battery cell (1) may be coupled to the electrode tab bundle, and thus the electrode assembly (10) and the lead tab (400) may be electrically connected to each other. Various welding methods including ultrasonic welding or a physical fastening method using a rivet or the like may be applied to the connection between the electrode tab bundle and the lead tab (400).

[0050] The lead tab (400) may be made of a conductive metal material. For example, the lead tab (400) may be made of nickel (Ni), copper (Cu), nickel-plated copper, aluminum (Al), etc. An insulating member (410) may be placed between the lead tab (400) and the case (500). For example, the insulating member (410) may be made of a material having both insulating and adhesive properties, and may be bonded to the sealing portion (502) of the case (500) while wrapping a portion of the lead tab (400), thereby ensuring electrical insulation between the lead tab (400) and the case (500) and preventing the sealing performance between the lead tab (400) and the sealing portion (502) from being impaired.

[0051] Meanwhile, the specific structure of the electrode assembly (10) and lead tab (400) according to the embodiments is not limited to that shown in FIGS. 1 and 2.

[0052] For example, unlike FIG. 2, the electrode assembly (10) may be configured in a form in which a first electrode plate (100) is arranged on one side of a single sheet of separator (300) folded in a zigzag shape, and a second electrode plate (200) is arranged on the other side.

[0053] Alternatively, unlike FIG. 2, the electrode assembly (10) may have a roll-type structure in which the first electrode plate (100) and the second electrode plate, each prepared as a single sheet, are rolled up with a separator (300) sandwiched between them.

[0054] In embodiments, the first electrode plate (100) and the second electrode plate (200) of the electrode assembly (10) may be plates having opposite polarities. For example, when the first electrode plate (100) is a negative electrode plate, the second electrode plate (200) may be a positive electrode plate.

[0055] The positive electrode plate (200) may have a structure in which a positive electrode active material layer (230) is formed on a current collector (210). For example, the active material layer (230) on the positive electrode plate (200) may be formed by applying a mixture of a positive electrode active material, a conductive material, and a binder to a current collector (210) made of an aluminum alloy. At this time, any known material used in the positive electrode plate (200) of a lithium secondary battery may be used as the materials for the positive electrode active material, the binder, the conductive material, and the current collector.

[0056] The negative electrode plate (100) of the battery cell (1) according to the embodiments may be made of a lithium metal sheet, unlike a conventional negative electrode plate.

[0057] In conventional cases, the negative electrode plate may have a structure in which a layer of negative electrode active material is formed on a current collector. For example, the negative electrode plate may be formed by applying a mixture of a negative electrode active material, a conductive agent, and a binder to a current collector made of a copper alloy material.

[0058] In contrast, the negative electrode plate (100) of the battery cell (1) according to the embodiments may have an integral structure composed of a negative electrode body portion (110) made of a lithium metal sheet and a negative electrode tab (120) arranged on one side of the negative electrode body portion (110). The lithium metal sheet is a flat sheet member made of a lithium or lithium alloy material, and the negative electrode body portion (110) and the negative electrode tab (120) according to the embodiments may be implemented by appropriately processing the shape of the lithium metal sheet.

[0059] A battery cell (1) to which a negative electrode plate (100) made of a lithium metal sheet is applied can omit a conventional negative electrode collector made of nickel (Ni), aluminum (Al), copper (Cu), etc., so that not only is it advantageous in reducing the weight of the battery cell (1), but it can also have a very high energy density.

[0060] However, if the negative electrode plate (100) and the negative electrode tab (120) arranged on one side of the negative electrode plate (100) are made of only lithium metal without a metal current collector, the electrode assembly (10) may be easily crumpled or broken during the manufacturing process due to the low mechanical strength of lithium, and there is a concern that the problem of lithium sticking to the manufacturing device may frequently occur, causing inefficiency in the manufacturing process.

[0061] In particular, when the electrode tab (120) of the negative plate (100) is made of lithium metal, there is a concern that the electrode tab (120) may be pressed and spread out during the ultrasonic welding process for joining the electrode tab (120) and the lead tab (400), causing a short circuit with other components of the battery cell (1) {e.g., the electrode tab (220) of the positive plate (200) or the case (500), etc.}, or that the lithium metal of the electrode tab (120) may stick to the welding device.

[0062] To solve these problems, the negative electrode plate (100) according to the embodiments can be used in a connection process with the lead tab (400) in a state where the electrode tab (120) is cooled and hardened through the electrode assembly manufacturing system (600) or the electrode assembly manufacturing method (S300) described through FIGS. 3 to 7. As the electrode tab (120) of the negative electrode plate (100) is cooled and hardened, the mechanical strength of the electrode tab (120) is significantly increased, thereby preventing lithium seizure problems and improving welding quality.

[0063] Hereinafter, with reference to Fig. 3, a method for manufacturing an electrode assembly (S300) is described.

[0064] Figure 3 is a flowchart showing a method for manufacturing an electrode assembly according to embodiments.

[0065] The electrode assembly and battery cell described in FIG. 3 include all the features of the electrode assembly (10) and battery cell (1) described in FIGS. 1 and 2, and any description overlapping with FIGS. 1 and 2 may be omitted.

[0066] A method for manufacturing an electrode assembly (10 of FIGS. 1 and 2) may include a preparation step (S310) of aligning electrode tabs (120, 220 of FIGS. 1 and 2) of electrode plates (100, 200 of FIG. 2), a cooling step (S320) of cooling at least some of the aligned electrode tabs (120, 220), and a connecting step (S330) of joining the cooled electrode tabs and lead tabs (400 of FIG. 1) to each other.

[0067] In the preparation step (S310), one or more first electrode plates (100 in FIG. 2) and one or more second electrode plates (200 in FIG. 2) may be alternately stacked with a separator (300 in FIG. 2) therebetween. For example, in the preparation step (S310), as previously illustrated in FIG. 2, a plurality of first electrode plates (100) and second electrode plates (200) may be alternately stacked in one direction with a separator (300) therebetween. At this time, the first electrode tabs (120) of the first electrode plates (100) may be aligned at a preset position to form a first electrode tab bundle, and the second electrode tabs (220) of the second electrode plates (200) may be aligned at a position spaced apart from the first electrode tab bundle to form a second electrode tab bundle.

[0068] In the cooling step (S320), at least one of the first electrode tab bundle or the aligned second electrode tab bundle can be cooled using a cooling device.

[0069] A cooling device in which a cooling step (S320) is performed may be configured to locally cool only the electrode tab bundles in the electrode assembly (10). For example, the cooling device may be a contact cooling type cooling device (620) described in FIGS. 5 and 6 (for a detailed description thereof, refer to the description of FIGS. 5 and 6). Alternatively, the cooling device may have a structure of a container that contains a liquid or gaseous coolant and has one open side, in which case the electrode tab bundles of the electrode assembly (10) may be immersed in the coolant contained in the container for a predetermined period of time to achieve a cooling effect. However, the specific configuration of the cooling device is not limited to that described above, and any configuration capable of locally cooling the electrode tab bundles of the electrode assembly (10) may be applied without limitation.

[0070] In the cooling step (S320), the target cooling temperature of the electrode tab bundle may be lower than room temperature (approximately 25°C). For example, the target cooling temperature of the electrode tab bundle may be 0°C or lower, and preferably approximately -10°C. However, the target cooling temperature of the electrode tab bundle is not limited to the above-described temperature, and may be appropriately increased or decreased depending on various variables such as the size of the electrode tab, the thickness of the electrode tab bundle, and the configuration of the connecting device that connects the lead tab (400) and the electrode tab.

[0071] As the bundle of electrode tabs is cooled in the cooling step (S320), the electrode tabs (e.g., 120) are hardened, thereby increasing their mechanical strength. In particular, when the electrode tabs (120) are made of lithium or an alloy containing lithium (hereinafter, such electrode tabs are also referred to as “lithium electrode tabs”), the strength and hardness of the lithium electrode tabs (120) can be significantly increased through the cooling step (S320). Accordingly, the lithium electrode tabs (120) can be prevented from being easily crumpled or bent during the manufacturing process of the electrode assembly (10). In addition, during the process of mutually connecting the electrode tabs (120, 220) and the lead tab (400) through the connecting step (S330) described below, the phenomenon of the electrode tabs (120, 220) being stuck to the connecting device can be prevented, while the lead tabs (400) and the electrode tabs (120, 220) can be strongly connected.

[0072] In the connection step (S330), the electrode tab and the lead tab (400) that have been cooled in the cooling step (S320) can be electrically connected by joining them together.

[0073] In the connection step (S330), various welding methods including ultrasonic welding or a physical fastening method using a rivet, etc., can be applied to the connection between the electrode tab bundle and the lead tab (400). For example, when the electrode tab (120) is made of lithium or an alloy containing lithium, an ultrasonic welding method can be applied to the connection between the electrode tab (120) and the lead tab (400).

[0074] Ultrasonic welding refers to a welding method that welds base materials by locally applying ultrasonic vibrations. During the ultrasonic welding process, a certain level of pressure or higher is applied to the workpieces to be welded, i.e., the electrode tabs (120, 220) and the lead tabs (400). However, when the electrode tabs (120) are made of lithium or an alloy containing lithium, it is difficult to apply ultrasonic vibrations with sufficient pressure due to the soft physical properties of lithium, and the problem of lithium sticking to the welding device frequently occurs while applying the vibrations.

[0075] However, since the lithium electrode tab (120) cooled through the cooling step (S320) according to the embodiments is cooled and hardened, thereby increasing its mechanical strength, ultrasonic welding can be performed smoothly. In particular, since the lithium electrode tab (120) is cooled and hardened, the lithium sticking problem can be prevented, and the ultrasonic output can be further increased, thereby significantly increasing the bonding strength of the electrode tab and the lead tab (400).

[0076] As illustrated in FIG. 3, the preparation step (S310), the cooling step (S320), and the connection step (S330) may be performed sequentially. In this case, the time interval during which the electrode assembly (10) transitions from the cooling step (S320) to the connection step (S330) may be short enough to maintain the cooling state of the electrode tab. That is, the electrode tab cooled to the target cooling temperature in the cooling step (S320) may be input into the connection step (S330) while maintaining the cooling state.

[0077] After the lead tab (400) and the electrode assembly (10) are interconnected through the connection step (S330), the electrode assembly (10) is housed in a case (500) through a casing step (not shown). In the casing step (not shown), a process of sealing the edge of the case (500) in which the electrode assembly (10) is housed may be additionally performed.

[0078] Hereinafter, with reference to FIGS. 4 to 7, an electrode assembly manufacturing system (600) capable of performing the method for manufacturing the electrode assembly (10) described above will be described.

[0079] FIG. 4 shows an exemplary configuration of an electrode assembly manufacturing system (600) according to embodiments.

[0080] Figure 5 shows an exemplary configuration of a cooling device (620).

[0081] FIG. 6 is a reference drawing exemplarily showing a state in which at least a portion of an electrode tab (120) is cooled by a cooling device (620).

[0082] Figure 7 shows an exemplary configuration of a connecting device (630).

[0083] The electrode assembly manufacturing system (600) described in FIGS. 4 to 7 is a system for manufacturing the electrode assembly (10) described through FIGS. 1 and 2, and can perform the electrode assembly manufacturing method (S300) described through FIG. 3, so any description overlapping with FIGS. 1 to 3 may be omitted.

[0084] An electrode assembly manufacturing system (600) may include a stacking device (610) for stacking and aligning a plurality of electrode plates (100, 200), a cooling device (620) for cooling at least one of the electrode tabs (120, 220) of the electrode plates (100, 200), and a connecting device (630) for connecting a lead tab (400) to the cooled electrode tab.

[0085] The stacking device (610) can alternately stack one or more first electrode plates (100) and one or more second electrode plates (200) with a separator (300) in between.

[0086] As the electrode plates (100, 200) are stacked and aligned in the stacking device (610), the first electrode tab (120) of the first electrode plate (100) can be aligned at a preset position to form a first electrode tab bundle, and the second electrode tab (220) of the second electrode plate (200) can be aligned at a position spaced apart from the first electrode tab (120) to form a second electrode tab bundle. That is, the stacking device (610) can perform the preparation step (S310) described above through FIG. 3.

[0087] The stacking device (610) according to the embodiments may be applied to various types of devices depending on the structure of the electrode assembly (10), and any device capable of alternately arranging first electrode plates (100) and second electrode plates (200) having opposite polarities with a separator (300) interposed therebetween may be applied without limitation.

[0088] The cooling device (620) can perform the cooling step (S320) described above through FIG. 3.

[0089] The cooling device (620) can be configured to locally cool the electrode tab (e.g., 120) of the electrode assembly (10), and various cooling methods can be applied to the cooling device (620), such as a cooling method by contact between a cooling member and the electrode tab (120), or a method of cooling by immersing the electrode tab (120) in a coolant.

[0090] FIG. 5 and FIG. 6 illustrate an embodiment of a cooling device (620) comprising a plurality of press parts (621, 622) capable of pressing and cooling an electrode tab (120).

[0091] Referring to FIGS. 5 and 6, the cooling device (620) may include a first press section (621) and a second press section (622) that move relative to each other in a direction toward each other to press the electrode tab.

[0092] In the cooling step (S320), the first press unit (621) and the second press unit (622) may be configured to press the electrode tabs. For example, when the electrode tabs (120) or the electrode tab bundle (TB) are positioned on the upper surface of the first press unit (621), the second press unit (622) may be lowered to press the electrode tabs (120) or the electrode tab bundle (TB).

[0093] A cooling path (621a, 622a) configured to allow a coolant to flow may be formed inside the first press section (621) and the second press section (622). While the coolant circulates through the cooling path (621a, 622a), the first press section (621) or the second press section (622) is cooled, and as the cooled first press section (621) or the second press section (622) comes into contact with the electrode tab (120), the electrode tab is cooled.

[0094] The refrigerant applied to the cooling device (620) may be, for example, liquid nitrogen. However, the type of refrigerant is not limited thereto, and any refrigerant capable of cooling the electrode tab (120) to the target cooling temperature may be applied.

[0095] In order to increase the contact time or contact area between the first press section (621) and the second press section (622) and the refrigerant, the cooling passages (621a, 622a) may be provided in a shape that is folded multiple times. However, the specific structure of the cooling passages (621a, 622a) is not limited to that illustrated in the drawing. In addition, the cooling passages (621a, 622a) may be arranged in only one of the first press section (621) and the second press section (622).

[0096] If necessary, either the first press section (621) or the second press section (622) may be omitted. For example, while the electrode tabs (120) or the electrode tab bundle (TB) are placed on a separate worktable, one press section may be lowered to pressurize and cool the electrode tabs (120) or the electrode tab bundle (TB).

[0097] At least one of the first press section (621) and the second press section (622) may be provided in a size sufficient to locally pressurize and cool only one of a pair of electrode tab bundles provided in the electrode assembly (10).

[0098] In the preparation step (S310), the electrode tab bundle (TB) aligned and stacked in one direction can be maintained in a dense state by being pressurized and cooled by the cooling device (620). That is, as the cooling device (620) pressurizes and cools the electrode tabs (120) aligned in one direction with a slight gap therebetween in the preparation step (S310), a cooled and hardened electrode tab bundle (TB) can be formed in which the electrode tabs are densely stacked. Accordingly, in the connection step (S330) following the cooling step (S320), the lead tab (400) and the electrode tab bundle (TB) can be easily aligned. Therefore, the cooling device (620) can also function as a kind of pre-welding device for easy welding of the lead tab (400) and the electrode tabs (120, 220).

[0099] Meanwhile, the cooling device (620) may further include a temperature sensor (not shown) capable of measuring the temperature of the electrode tab bundle (TB). The temperature sensor (not shown) may be configured to detect the temperature of the electrode tab bundle (TB) in real time. The cooling device (620) may cool the electrode tab bundle (TB) through feedback control using the temperature value detected by the temperature sensor (not shown). For example, the first press unit (621) and the second press unit (622) of the cooling device (620) may be configured to pressurize the electrode tab bundle (TB) until the temperature of the electrode tab bundle (TB) reaches a preset target cooling temperature, and release the pressurization when the target cooling temperature is reached.

[0100] The electrode tab (120) or electrode tab bundle (TB) cooled in the cooling device (620) can then be fed into the connecting device (630) and electrically connected to the lead tab (400).

[0101] FIG. 7 shows an embodiment of a connecting device (630) capable of ultrasonically welding a bundle of electrode tabs and a lead tab (400).

[0102] Referring to FIG. 7, the connecting device (630) may include a first welding member (631) on which a lead tab (400) and a cooled electrode tab are mounted, and a second welding member (632) that ultrasonically welds the lead tab (400) and the electrode tab, which are disposed on the first welding member (631). For example, the first welding member (631) may be an anvil, and the second welding member (632) may be a horn.

[0103] The connection device (630) can perform the connection step (S330 of FIG. 3) described above through FIG. 3. The connection step (S330) by the connection device (630) can be largely composed of the following two steps.

[0104] First, a first connection step is performed to align the cooled electrode tab bundle and the lead tab (400) on the connection member. In the first connection step, the cooled electrode tab (120) or the electrode tab bundle (TB) and the lead tab (400) can be aligned in an overlapping state on the first welding member (631) in a cooling device (620). At this time, the temperature of the electrode tab (120) aligned on the first welding member (631) can be equal to or lower than the temperature cooled by the cooling device (620), for example, 0°C.

[0105] Thereafter, in the second connection step, ultrasonic welding is performed while the first welding member (631) and the second welding member (632) are pressed against the electrode tab (120) and the lead tab (400). For example, in the second connection step, the second welding member (632) is lowered to apply pressure to the electrode tab (120) and the lead tab (400) by ultrasonic vibration, and accordingly, the electrode tab (120) and the lead tab (400) are mutually joined and electrically connected.

[0106] As described above, the lithium electrode tab (120) cooled through the cooling step (S320) is cooled and hardened, thereby increasing its mechanical strength, and thus, ultrasonic welding can be smoothly performed by the connecting device (630). In particular, as the lithium electrode tab (120) is cooled and hardened, the lithium sticking problem can be prevented, and the ultrasonic output can be further increased, thereby significantly increasing the bonding strength of the electrode tab and the lead tab (400).

[0107] In addition to the above description, the specific configuration of the connecting device (630) including the first welding member (631) and the second welding member (632) can be applied without limitation to the technical idea of ​​an ultrasonic welding device used in the production of a lithium ion battery cell (1).

[0108] Meanwhile, although not shown in the drawing, the electrode assembly manufacturing system (600) may further include at least one of a first transport device (not shown) that transports the assembled electrode assembly (10) from the stacking device (610) to the cooling device (620) and a second transport device (not shown) that transports the cooled electrode assembly (10) from the cooling device (620) to the connecting device (630).

[0109] However, in embodiments, at least two of the stacking device (610), the cooling device (620), and the connecting device (630) may be configured integrally, in which case the cooling device (620) or the connecting device (630) may approach the electrode assembly (10) placed on the worktable without a separate transport device, thereby performing the cooling step (S320) or the connecting step (S330).

[0110] According to embodiments, the connection process with the lead tab (400) can be performed by cooling and hardening an electrode tab (120) made of lithium or an alloy containing lithium, thereby increasing the mechanical rigidity of the electrode tab (120).

[0111] Since the electrode tab (120) in a cooled state has better rigidity than the electrode tab (120) in a non-cooled state, the output of a connecting device, for example, an ultrasonic welding device, can be increased, thereby increasing the bonding strength between the electrode tab (120) and the lead tab (400).

[0112] In addition, since the electrode tab (120) in a cooled state has superior rigidity than the electrode tab (120) in a non-cooled state, the ease of handling and stability can be increased during the manufacturing process of the electrode assembly (10). In particular, since the phenomenon of lithium metal spreading can be suppressed during the bonding process between the electrode tab (120) and the lead tab (400), the lithium electrode tab can be prevented from spreading during the ultrasonic welding process, causing interference with other components and hindering the sealing performance of the case (500).

[0113] In addition, since the electrode tab (120) in a cooled and hardened state through the cooling process is not easily attached to a manufacturing device, for example, a connecting device (630), process inefficiency caused by the attachment phenomenon of lithium metal can be eliminated.

[0114] While various embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations are possible without departing from the technical spirit of the present invention as set forth in the claims. Furthermore, the embodiments described above may be implemented by deleting some components, and the embodiments may be implemented in combination with each other.

[0115] [Explanation of symbols]

[0116] 1... battery cell 10... electrode assembly

[0117] 100... 1st electrode plate 120... 1st electrode tab

[0118] 200... Second electrode plate 220... Second electrode tab

[0119] 300... separator 400... lead tab

[0120] 500... Case 600... Electrode Assembly System

[0121] 610... Stacking device 620... Cooling device

[0122] 621... 1st press section 622... 2nd press section

[0123] 621a, 622a... Cooling Euro 630... Connecting Device

[0124] 631... First welding member 632... Second welding member

Claims

1. A preparatory step of aligning electrode tabs of one or more first electrode plates; A cooling step for cooling the above electrode tab; and A method for manufacturing an electrode assembly, comprising a connecting step in which the cooled electrode tab and the lead tab are joined to each other.

2. In paragraph 1, A method for manufacturing an electrode assembly, wherein the electrode tabs of the at least one first electrode plate are made of lithium or an alloy containing lithium.

3. In paragraph 1, A method for manufacturing an electrode assembly, wherein in the cooling step, the electrode tab is cooled in a pressurized state by a cooling device.

4. In paragraph 3, The cooling device includes a first press section and a second press section that move relative to each other in a direction approaching each other and press the electrode tab, A method for manufacturing an electrode assembly, wherein at least one of the first press portion and the second press portion includes a cooling path through which a refrigerant flows.

5. In paragraph 4, A method for manufacturing an electrode assembly, wherein the refrigerant flowing through the cooling channel is liquid nitrogen.

6. In paragraph 1, A method for manufacturing an electrode assembly, wherein in the above preparation step, the one or more first electrode plates are alternately laminated with one or more second electrode plates with a separator therebetween, and the one or more second electrode plates have a polarity opposite to that of the one or more first electrode plates.

7. In paragraph 6, In the above preparation step, an electrode tab bundle is formed in which the electrode tabs of the one or more first electrode plates are laminated, A method for manufacturing an electrode assembly, wherein the electrode tab bundle is cooled in the above cooling step.

8. In paragraph 6, A method for manufacturing an electrode assembly, wherein the at least one first electrode plate is a negative electrode plate made of lithium or an alloy containing lithium.

9. In paragraph 1, The above connection steps are A first connecting step of aligning the cooled electrode tab and the lead tab on the connecting device; and A method for manufacturing an electrode assembly, comprising a second connecting step in which the electrode tab and the lead tab are connected by the connecting device.

10. In paragraph 9, A method for manufacturing an electrode assembly, wherein the temperature of the electrode tab in the first connecting step is 0°C or less.

11. In paragraph 9, A method for manufacturing an electrode assembly, wherein in the second connecting step, the electrode tab and the lead tab are joined through ultrasonic welding.

12. An electrode assembly manufactured by the electrode assembly manufacturing method according to Article 1; and A battery cell comprising a case enclosing the electrode assembly.

13. A stacking device aligning one or more first electrode plates and one or more second electrode plates having opposite polarities; A cooling device for cooling the electrode tabs of the one or more first electrode plates; and An electrode assembly manufacturing system comprising a connecting device connecting the cooled electrode tab and the lead tab.

14. In paragraph 13, The cooling device includes a first press section and a second press section that move relative to each other in a direction approaching each other and press the electrode tab, An electrode assembly manufacturing system, wherein at least one of the first press section and the second press section includes a cooling channel through which a refrigerant flows.

15. In paragraph 13, An electrode assembly manufacturing system wherein the above connecting device is configured to ultrasonically weld the cooled electrode tab and the lead tab.

Images