Manufacturing device for stack cell including induction heating unit and manufacturing method for stack cell using induction heating process

Abstract

A stack cell manufacturing device according to one embodiment of the present invention is a device for laminating a stack cell comprising an anode, a cathode, and a separator interposed between the anode and the cathode, wherein the device comprises an induction heating unit for induction heating the stack cell, and the induction heating unit comprises two adjacent coil portions among a plurality of coil portions, and the direction in which the induction current moves in the two coil portions is the same.

Description

Technology Field

[0001] The present invention relates to a stack cell manufacturing apparatus including an induction heating unit and a stack cell manufacturing method applying an induction heating method. Background Technology

[0002] In modern society, as the use of portable devices such as mobile phones, laptops, camcorders, and digital cameras has become commonplace, the development of technologies related to such mobile devices is becoming active. Furthermore, rechargeable secondary batteries are being utilized as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (P-HEVs) as a solution to address air pollution caused by conventional gasoline vehicles using fossil fuels; consequently, the need for the development of secondary batteries is increasing.

[0003] Secondary batteries can be classified according to the shape of the battery case into cylindrical batteries and prismatic batteries in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-type case made of a laminate sheet.

[0004] Furthermore, secondary batteries are also classified according to the structure of the electrode assembly, which consists of a stacked structure comprising a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes. Representative examples include a jelly-roll type (wound type) electrode assembly, in which long sheet-type positive and negative electrodes are wound with a separator interposed, and a stack type (laminated type) electrode assembly, in which multiple positive and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator interposed. Recently, to address the problems associated with the aforementioned jelly-roll type and stack type electrode assemblies, a stack / folding type electrode assembly, which is a hybrid form of the jelly-roll type and the stack type, has also been developed.

[0005] Meanwhile, in manufacturing a stacked or stacked / folded electrode assembly, heat and pressure may be applied to a laminate in which an anode, a separator, and a cathode are stacked in order to bond the electrodes and the separator to each other. Specifically, the laminate may be positioned between heating plates, and heat and pressure may be applied to fix the interior of the laminate.

[0006] However, applying heat and pressure to the laminate to bond the electrodes and separators contained in the laminate requires a long time and energy.

[0007] The cells, particularly the separators, can be damaged by the heat and pressure applied after cell stacking. If the cells and separators are damaged in this way, it can cause lithium deposition during the charging and discharging process of the finished cells. The problem to be solved

[0008] The problem to be solved by the present invention is to provide a stack cell manufacturing apparatus including an induction heating unit to prevent cell damage and a stack cell manufacturing method applying an induction heating process.

[0009] However, the problems that the embodiments of the present invention aim to solve are not limited to the problems described above and can be expanded in various ways within the scope of the technical ideas included in the present invention. means of solving the problem

[0010] A stack cell manufacturing device according to one embodiment of the present invention is a device for laminating a stack cell comprising an anode, a cathode, and a separator interposed between the anode and the cathode, wherein the device comprises an induction heating unit for induction heating the stack cell, and the induction heating unit comprises two adjacent coil portions among a plurality of coil portions, and the direction in which the induction current moves in the two coil portions is the same.

[0011] The above-described induction heating unit includes an input unit into which the induction current is input and an output unit into which the induction current is output, and the input unit may be connected in a vertical direction to one of the coil units of the two layers.

[0012] The above-described induction heating unit includes a first coil unit connected to the input unit and a second coil unit connected to the output unit, and the first coil unit and the second coil unit may be arranged on the same plane.

[0013] The first plane in which the first coil portion and the second coil portion are arranged can be positioned perpendicular to the stacking direction of the stack cell.

[0014] The input section is arranged on a second plane having a different level from the first plane in which the first coil section is arranged, and the output section is arranged on the second plane, and one of the input section and the output section arranged on the second plane may intersect the two-layer coil section arranged on the first plane.

[0015] The two-layer coil portion may be disposed between the input portion and the stack cell.

[0016] The above induction heating unit may include the two-layer coil unit and a plate containing the two-layer coil unit.

[0017] The above plate may be formed of epoxy material.

[0018] The above induction heating unit includes a first induction heating unit and a second induction heating unit located at the bottom and top of the stack cell, respectively, and the two-layer coil portion included in the first induction heating unit and the two-layer coil portion included in the second induction heating unit may have the same direction of movement of the induction current.

[0019] A method for manufacturing a stack cell according to another embodiment of the present invention comprises, in a method for laminating a stack cell comprising an anode, a cathode, and a separator interposed between the anode and the cathode, the steps of: arranging an induction heating member on the stack cell; arranging two adjacent coil members included in the induction heating member so as to be arranged on the same plane; and inducing heating the stack cell while an induction current moves in the same direction in the two adjacent coil members.

[0020] In the above-mentioned induction heating step, the input portion into which the induction current is input is connected in a vertical direction to one of the coil portions of the two layers, thereby forming a spaced-apart space between the input portion and the stack cell.

[0021] The two-layer coil portion is disposed in a spaced-apart between the input portion and the stack cell, so that the induced current flowing in the input portion and the induced current flowing in the two-layer coil portion can cross each other.

[0022] One edge of the above-mentioned induction heating unit may be positioned so as to be spaced apart from the edge of the stack cell by a range of 2 mm or less.

[0023] By the above induction heating, the magnetic field can penetrate the interior of the stack cell and heat can be transferred to the cell inside the stack cell.

[0024] The above method for manufacturing a stack cell may further include a step of simultaneously pressurizing the stack cell during the step of induction heating the stack cell.

[0025] In the step of induction heating the stack cell, the peak temperature can be managed to reach a range from a temperature 50 degrees Celsius lower than the melting temperature of the separator contained in the stack cell to the melting temperature of the separator.

[0026] The pressure applying pressure to the stack cell can be managed in the range of 1.0 MPa to 3.0 MPa.

[0027] The step of induction heating the stack cell can proceed with the heating by dividing the output of the induction heating into multiple stages in order to control the heating profile and convergence temperature of the inner layer of the stack cell and the outer layer of the stack cell to an equal level. Effects of the invention

[0028] According to the embodiments, cell damage can be prevented by using an induction heating method in the lamination process after cell stacking to perform bonding between the electrode and the separator or bonding between individual cells.

[0029] In addition, lamination can be performed to achieve sufficient adhesion while using low pressure to improve process efficiency.

[0030] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0031] FIG. 1 is a diagram showing that a magnetic field is formed by a stack cell manufacturing device including an induction heating unit according to one embodiment of the present invention. Figure 2 is a graph comparing the temperatures inside and outside the cell over time when a stack cell is manufactured using the stack cell manufacturing device of Figure 1. Figure 3 is a drawing showing a stack cell manufacturing device according to a comparative example. Figure 4 is a graph comparing the temperatures inside and outside the cell over time when a stack cell is manufactured using the stack cell manufacturing device of Figure 3. FIG. 5 is a perspective view showing an induction heating unit included in the stack cell manufacturing device of FIG. 1. FIG. 6 is a cross-sectional view showing a stack cell manufacturing apparatus according to one embodiment of the present invention. Figure 7 is a plan view showing the stack cell manufacturing device of Figure 6. FIG. 8 is a flowchart illustrating a stack cell manufacturing method according to another embodiment of the present invention. Figure 9 is a graph showing the temperature deviation at the completion of heating when a stack cell is manufactured using a heating press device according to the comparative example of Figure 3. FIG. 10 is a graph showing a cell temperature profile in a stack cell manufacturing method according to another embodiment of the present invention. Specific details for implementing the invention

[0032] Hereinafter, various embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms other than those described below, and the scope of the present invention is not limited by the embodiments described herein.

[0033] To clearly explain the present invention, parts unrelated to the description have been omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0034] In addition, the size and thickness of each component shown in the drawings have been arbitrarily enlarged or reduced for convenience of explanation, so it is obvious that the content of the present invention is not limited to what is illustrated. In the drawings below, the thickness of each layer has been enlarged to clearly represent various layers and regions. Also, in the drawings below, the thickness of some layers and regions has been exaggerated for convenience of explanation.

[0035] Furthermore, when describing a part such as a layer, membrane, region, or plate as being "above" or "on" another part, this should be interpreted to include not only cases where the corresponding part is "directly above" the other part, but also cases where there is another part in between. Conversely, when describing a corresponding part such as a layer, membrane, region, or plate as being "directly above" another part, it may mean that there is no other part in between. Additionally, stating that a part is "above" or "on" a reference part means being located above or below the reference part, and does not necessarily mean being located "above" or "on" in the opposite direction of gravity. Meanwhile, just as describing a part as being "above" or "on" another part can be understood by referring to the aforementioned content, describing a part as being "below" or "under" another part can also be understood.

[0036] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0037] Additionally, throughout the specification, "planar" means when the part is viewed from above, and "cross-sectional" means when the cross-section obtained by cutting the part vertically is viewed from the side.

[0038] FIG. 1 is a diagram showing a magnetic field being formed by a stack cell manufacturing device including an induction heating unit according to an embodiment of the present invention. FIG. 2 is a graph comparing the temperatures inside and outside the cell over time when a stack cell is manufactured using the stack cell manufacturing device of FIG. 1.

[0039] Referring to FIG. 1, the stack cell manufacturing device according to the present embodiment includes an induction heating unit (200, 300) disposed at the upper and lower portions of a stack cell (100) comprising an anode, a cathode, and a separator interposed between the anode and the cathode. The induction heating unit (200, 300) according to the present embodiment may be disposed one at each at the upper and lower portions of the stack cell (100) with respect to the direction (Z-axis) in which the electrodes and the separator are stacked within the stack cell (100).

[0040] In this embodiment, although not specifically illustrated, the stack cell (100) according to this embodiment may include a battery cell in which a separator / negative electrode / separator / positive electrode are sequentially stacked. However, the two outermost electrodes may have different types, such as positive electrode / separator / negative electrode / separator / positive electrode / separator / negative electrode, or positive electrode / separator / negative electrode, or the two outermost electrodes may have the same types, such as positive electrode / separator / negative electrode / separator / positive electrode, or negative electrode / separator / positive electrode / separator / negative electrode. The stack cell (100), which is configured by stacking battery cells, may be formed by various combinations based on a configuration in which a separator is interposed between a negative electrode and a positive electrode.

[0041] Through the induction heating unit (200, 300), a laminate in which an anode, a separator, and a cathode are stacked can be heated to bond the electrodes and the separator to each other. Additionally, pressure may be applied. At this time, the polymer of the separator and the binder of the electrode can be bonded.

[0043] According to the present embodiment, by using an induction heating unit (200, 300) located adjacent to a stack cell (100), a magnetic field (MF) penetrates into the interior of the stack cell (100) by electromagnetic induction in a non-contact manner, thereby enabling the uniform generation of heat to the cells located inside the stack cell (100). Therefore, heat can be efficiently transferred into the interior of the stack cell (100), and high-speed and high-efficiency lamination can be achieved while minimizing damage to the cells.

[0045] Referring to FIG. 2, when a stack cell is manufactured using a stack cell manufacturing device according to the present embodiment, heat is evenly transferred to the cell at the center of the stack cell (100) due to the magnetic field penetrating the inside of the cell, and it can be seen that the temperature inside the cell and the temperature outside the cell increase over time with almost no difference.

[0047] FIG. 3 is a drawing showing a stack cell manufacturing device according to a comparative example. FIG. 4 is a graph comparing the temperatures inside and outside the cell over time when a stack cell is manufactured using the stack cell manufacturing device of FIG. 3.

[0048] Referring to FIG. 3, the stack cell manufacturing device according to the comparative example forms heating press sections (20, 30) at the upper and lower parts of the stack cell (10), respectively. In this heating press method, heat is transferred to the heating press sections (20, 30) through a heater (15), and heat can be transferred from the outside to the inside of the stack cell (10). There is a problem in that the surface of the stack cell (10) in direct contact with the heating press sections (20, 30) is excessively heated, while sufficient heat is not transferred to the cell located inside the stack cell (10). Referring to FIG. 4, it can be seen that heat is not evenly transferred to the sub-cell at the center of the stack cell (10), so the temperature inside the cell is lower than the temperature outside the cell in terms of the level of temperature rise due to heating. In this case, strong pressure may be required to transfer sufficient heat to the inside of the cell.

[0049] As such, when using a heating press method with a heater (15) as a heat source, the cells located on the outer edge of the stack cell (10) are exposed to high temperature and high pressure for a long time, causing problems such as damage to the separator or electrode or shrinkage. Specifically, thermal stress is generated during the process of heat transfer from the outside to the inside, which can cause misalignment between cells or deformation of the internal structure. In addition, since the heating press method takes a long time for heat transfer, it can cause a decrease in productivity in the battery manufacturing process where high-speed production is required.

[0051] FIG. 5 is a perspective view showing an induction heating unit included in the stack cell manufacturing device of FIG. 1. FIG. 6 is a cross-sectional view showing a stack cell manufacturing device according to an embodiment of the present invention. FIG. 7 is a plan view showing the stack cell manufacturing device of FIG. 6.

[0052] Referring to FIGS. 5 and 6, the induction heating unit (200, 300) according to the present embodiment may include a first induction heating unit (200) disposed below the stack cell (100) and a second induction heating unit (300) disposed above the stack cell (100). The first and second induction heating units (200, 300) may each include a first coil assembly (210) and a second coil assembly (310).

[0053] As illustrated in FIG. 5, the second induction heating unit (300) is described as follows: the induction heating unit (300) according to the present embodiment includes an input unit (310E) into which an induction current is input and an output unit (310D) into which an induction current is output. The input unit (310E) is connected to a power source (not shown) that generates alternating current (AC) so that an induction current can be input to the induction heating unit (300).

[0054] The input unit (310E) according to the present embodiment is connected to the first coil unit (310a), and the first coil unit (310a) may include four coil units (310a1, 310a2, 310a3, 310a4) that are bent vertically in a counterclockwise direction with respect to the direction in which the induced current moves on the upper surface of the stack cell (100). Specifically, the first coil unit (310a1) is extended in the -Y axis direction and is bent vertically at one end to connect with the second coil unit (310a2), the second coil unit (310a2) is extended in the X axis direction and is bent vertically at one end to connect with the third coil unit (310a3), the third coil unit (310a3) is extended in the Y axis direction and is bent vertically at one end to connect with the fourth coil unit (310a4), and the fourth coil unit (310a4) may be extended in the -X axis direction. However, the angle at which the coil units are connected may be modified, and the first coil portion (310a) may be formed in a spiral shape.

[0055] The output unit (310D) according to the present embodiment is connected to the second coil unit (310b), and the second coil unit (310b) can be connected to one end of the first coil unit (310a).

[0056] The second coil section (310b) may include four coil units (310b1, 310b2, 310b3, 310b4) that are bent vertically in a counterclockwise direction with respect to the direction in which the induced current moves on the upper surface of the stack cell (100). Specifically, the first coil unit (310b1) may be extended in the -Y axis direction and bent vertically at one end to be connected to the second coil unit (310b2), the second coil unit (310b2) may be extended in the X axis direction and bent vertically at one end to be connected to the third coil unit (310b3), the third coil unit (310b3) may be extended in the Y axis direction and bent vertically at one end to be connected to the fourth coil unit (310b4), and the fourth coil unit (310b4) may be extended in the -X axis direction. However, the angle at which the coil units are connected may be modified, and the second coil part (310b) may be formed in a spiral shape.

[0057] In the induction heating unit (300) according to the present embodiment, the first coil unit (310a) and the second coil unit (310b) are arranged on the same plane, and the first coil unit (310a) may be located inside the second coil unit (310b). The first coil unit (310a) and the second coil unit (310b) may be arranged on the same first plane, and the first plane may be a plane arranged perpendicular to the stacking direction of the stack cell (100). For example, the electrode and the separator within the stack cell (100) are stacked in the Z-axis direction of FIG. 5, and the first plane on which the first coil unit (310a) and the second coil unit (310b) are arranged may be a plane perpendicular to the Z-axis direction.

[0058] As illustrated in FIG. 5, the first coil section (310a) and the second coil section (310b) form two adjacent coil sections (ACP), and the direction in which the induced current travels in the two coil sections (ACP) is the same. According to the present embodiment, by forming at least two coil sections (ACP) among a plurality of coil sections, the heat distribution generated in the stack cell (100) is uniform, and conditions can be formed where heat easily penetrates into the stack cell (100). The two coil sections (ACP) can be placed between the input section (310E) and the stack cell (100). FIG. 5 illustrates a case in which the first coil section (310a) and the second coil section (310b) each form a coil section of one turn, thereby forming a two-layer coil section (ACP), but is not limited thereto, and at least one of the first coil section (310a) and the second coil section (310b) may form a coil section of multiple turns to form a two-layer or more coil section (ACP).

[0059] According to the present embodiment, the input section (310E) into which the induced current is input may be connected in a vertical direction to one of the first coil section (310a) and the second coil section (310b) that form a two-layer coil section (ACP). For example, as shown in FIG. 5, one end of the input section (310E) may be connected to the first coil section (310a) through the first connection section (330a) of the first coil section (310a) so that the induced current may flow.

[0060] On the other hand, the output section (310D) from which the induced current is output may be connected in a vertical direction to the other of the first coil section (310a) and the second coil section (310b) that form the two-layer coil section (ACP). For example, as shown in FIG. 5, one end of the output section (310D) may be connected to the second coil section (310b) through the second connection section (330b) of the induction heating section (300) so that the induced current may flow. In this way, the connection section (330) including the first and second connection sections (330a, 330b) may be a part that connects the first and second coil sections (310a, 310b), which are components of the coil assembly (310) placed at different levels, the input section (310E), and the output section (310D).

[0061] According to the present embodiment, the input section (310E) may be arranged on a second plane having a different level from the first plane in which the first coil section (310a) is arranged, and the output section (310D) may also be arranged on the second plane. The second plane may be located at a higher level than the first plane relative to the stack cell (100). The input section (310E) and the output section (310D) may be arranged side by side on the same second plane. At this time, one of the input section (310E) and the output section (310D) arranged on the second plane may intersect with the two-layer coil section (ACP) arranged on the first plane. For example, as shown in FIG. 5, the extended portion of the input section (310E) and the extended portion of the two-layer coil section (ACP) may intersect each other.

[0062] According to the present embodiment, by having a gap between the input section (310E) and the stack cell (100), the magnetic field is concentrated in the section where the first coil section (310a) and the stack cell (100) overlap vertically and the induced current enters, which can cause damage to the cell due to the high temperature. In this way, by forming a gap between the input section (310E) and the stack cell (100), damage to the cell due to overheating at the edge of the stack cell (100) can be prevented.

[0063] Additionally, the input section (310E) is connected to the first coil section (310a) so that the induced current has a bending direction, thereby forming the same direction in which the induced current moves in the two-layer coil section (ACP) as described above. For example, the first connection section (330a) shown in FIG. 5 can change the direction of the induced current by connecting the coil unit (310a1) of the first coil section (310a) and the input section (310E). At this time, the direction of the induced current can be changed at least three times. If a bending structure is not formed when the input section (310E) and the first coil section (310a) are connected, the direction in which the induced current moves in the two-layer coil section (ACP) will differ, and interference may occur.

[0064] The output section (310D) can be connected to the coil unit (310b4) of the second coil section (310b) so that the induced current has a bending direction. For example, the second connection section (330b) shown in FIG. 5 can change the direction of the induced current by connecting the coil unit (310b4) of the second coil section (310b) and the output section (310D). At this time, the direction of the induced current can be changed at least twice. In this way, by forming a bending structure between the output section (310D) and the second coil section (310b), cell damage caused by overheating at the edge of the stack cell (100) can be prevented.

[0065] Although the above description was based on the second induction heating unit (300), the same content may be applied to the first induction heating unit (200). The first induction heating unit (200) according to the present embodiment includes an input unit (210E) into which an induction current is input and an output unit (210D) into which an induction current is output. The input unit (210E) is connected to a power source (not shown) that generates alternating current, so that an induction current can be input to the induction heating unit (200). In addition, all the content regarding the second induction heating unit (300) described above may be applied to the first induction heating unit (200). Specifically, the second induction heating unit (300) and the first induction heating unit (200) may have a mirror-symmetric structure with respect to the XY plane. At this time, the direction of movement of the induction current may be the same for the two-layer coil unit included in the first induction heating unit (200) and the two-layer coil unit (ACP) included in the second induction heating unit (300). If the direction of the induction current flowing in the first induction heating unit (200) and the second induction heating unit (300) is different from each other, the magnetic fields may cancel each other out and the heating efficiency may decrease.

[0066] Additionally, the first and second coil sections (not shown) included in the first induction heating section (200) are arranged on the same first plane, and the input section (210E) and output section (210D) included in the first induction heating section (200) are arranged on a second plane having a different level from the first plane. At this time, unlike the second induction heating section (300), the first plane in the first induction heating section (200) may be arranged at a higher level than the second plane in the first induction heating section (200) relative to the stack cell (100). That is, the first plane of the first induction heating section (200) may be arranged closer to the stack cell (100) than the second plane of the first induction heating section (200).

[0067] Referring to FIG. 6, the first induction heating unit (200) according to the present embodiment includes a first coil assembly (210) and a first plate (250) containing the first coil assembly (210), and the second induction heating unit (300) according to the present embodiment may include a second coil assembly (310) and a second plate (350) containing the second coil assembly (310).

[0068] The first coil assembly (210) according to the present embodiment includes a two-layer coil portion (ACP) described in FIG. 5, and the two-layer coil portion (ACP) may be contained within the first plate (250). The second coil assembly (310) according to the present embodiment includes a two-layer coil portion (ACP) described in FIG. 5, and the two-layer coil portion (ACP) may be contained within the second plate (350). The first and second plates (250, 350) according to the present embodiment may be formed of an epoxy material.

[0069] The stack cell manufacturing device according to the present embodiment may further include a press unit (500) for pressurizing the stack cell (100). The press unit (500) may include a first press unit (510) disposed below the first plate (250) and a second press unit (520) disposed above the second plate (350). The press unit (500) can provide a pressurizing force to the stack cell (100) during the lamination process of the stack cell (100), and since the first and second plates (250, 350) made of epoxy material surround the first and second coil assemblies (210, 310), the pressure of the press unit (500) can be transmitted to the stack cell (100) without damaging the first and second coil assemblies (210, 310). The first and second plates (250, 350) are formed flat so that they can press the stack cell (100) with uniform pressure.

[0070] The first and second plates (250, 350) are formed of an epoxy material, which has the effect of preventing the structure of the first and second plates (250, 350), including the first and second coil assemblies (210, 310), from deforming during repeated operations. Additionally, by using an epoxy material for the first and second plates (250, 350), the melting problem that occurs when using materials such as PEEK (polyetheretherketone) can be prevented. Furthermore, since the first and second plates (250, 350) include a surface that contacts the stack cell (100), they must be robust in terms of temperature and pressure during repeated operations to prevent deformation and allow for repeated use for a long time; according to the present embodiment, this effect can be achieved by using an epoxy material.

[0071] In addition, according to the present embodiment, the first and second plates (250, 350) formed of epoxy material may have thermal insulation properties so that heat generated from the first and second coil assemblies (210, 310) is not transferred to the first and second plates (250, 350). The stack cell (100) receives heat from the induction heating of the first and second coil assemblies (210, 310), but if the heat of the first and second coil assemblies (210, 310) itself is transferred to the stack cell (100) in addition to this heat, it receives heat twice, which may cause other problems due to high heat. For example, damage to the separator, such as bullet marks, may occur due to double heat transfer. In addition, although the temperature applied to the stack cell (100) by induction heating according to the present embodiment can be controlled, the heat of the first and second coil assemblies (210, 310) itself is outside the control range, so if the temperature of the first and second coil assemblies (210, 310) itself is high, the stack cell (100) receives high heat, and if the temperature of the first and second coil assemblies (210, 310) itself is low, the heat received by the stack cell (100) is low, which may affect the quality of the stack cell (100).

[0072] Referring to FIG. 7, in a stack cell manufacturing device according to the present embodiment, when a stack cell (100) is pressurized using induction heating as a heat source, the temperature of the cell end may be higher than the inside of the cell due to the edge effect of the induction heating, and thus the adhesion of the cell end may become relatively stronger. In such cases, the cell edge may overheat. To prevent this overheating problem, according to the present embodiment, the coil assembly (310) of the induction heating unit may be spaced apart from the stack cell edge by a first distance (T1) and a second distance (T2) when viewed on the XY plane, as shown in FIG. 5 and FIG. 7. At this time, the first distance (T1) or the second distance (T2) may be in the range of approximately 1 millimeter to 3 millimeters. If the first distance (T1) and / or the second distance (T2) is less than 1 millimeter, the temperature rise in the stack cell (100) may occur rapidly, and if it exceeds 3 millimeters, the effect of the stack cell (100) being heated may decrease.

[0074] FIG. 8 is a flowchart illustrating a stack cell manufacturing method according to another embodiment of the present invention.

[0075] Referring to FIG. 8, the method for manufacturing a stack cell according to the present embodiment includes the step (S1) of placing an induction heating unit on the stack cell.

[0076] A first induction heating unit may be placed at the bottom of the stack cell along the stacking direction of the stack cell, and a second induction heating unit may be placed at the top of the stack cell.

[0077] The stack cell manufacturing method includes the step (S2) of arranging two layers of coil portions included in the induction heating portion so as to be arranged on the same plane.

[0078] By arranging two layers of coil sections on the same plane so that an induced current flows in the same direction as described below, a larger magnetic field can be formed, and the cell exterior and cell interior within the stack cell can be heated evenly. The induction heating method according to the present embodiment may be a method of heating a conductor through the heat generated when the magnetic field created when a high-frequency alternating current flows through an induction coil comes close to a third conductor.

[0079] The method for manufacturing a stack cell according to the present embodiment includes the step (S3) of inductively heating the stack cell while the inductive current moves in the same direction in two layers of coil portions.

[0080] In the step of induction heating, an input section into which an induction current is input is connected vertically to one of the coil sections of the two layers of coil sections, thereby forming a spaced-apart space between the input section and the stack cell.

[0081] At this time, a double coil section is placed in the spaced-apart space between the input section and the stack cell, so that the induced current flowing in the input section and the induced current flowing in the double coil section can cross each other. When the induced current entering through the input section generates a magnetic field and a heat source for initial heating is provided to the stack cell, the phenomenon of overheating of the stack cell edge section caused by the magnetic field suddenly penetrating the stack cell can be mitigated.

[0082] One edge of the induction heating unit can be positioned so as to be spaced from the edge of the stack cell by approximately 2 millimeters (mm) or less. Through this structure, the cell edge can be prevented from overheating.

[0083] According to the present embodiment, a magnetic field can penetrate the interior of a stack cell by induction heating, allowing heat to be transferred to the cell inside the stack cell.

[0084] In the step of induction heating the stack cell according to the present embodiment, the peak temperature can be managed to be reached within the range of the melting temperature of the separator contained in the stack cell minus 50 degrees Celsius to the melting temperature of the separator. Here, the peak temperature can be defined as the highest point of the temperature applied to the stack cell. The peak temperature may be the temperature at which the separator (e.g., including PE / PP / coating layer) and the electrode (surface binder) adhere to each other. According to the present embodiment, damage to the separator can be prevented by managing the temperature range as described above.

[0085] The method for manufacturing a stack cell according to the present embodiment includes, in the step of induction heating the stack cell, a step (S4) of simultaneously pressurizing the stack cell.

[0086] According to the present embodiment, the stack cells can be inductively heated and simultaneously pressurized to facilitate adhesion between cells. At this time, the pressure applied to the stack cells can be managed within a range of approximately 1.0 MPa to 3.0 MPa (approximately 2.0 MPa). According to the present embodiment, since induction heating can be used to heat the inside of the stack cells uniformly, high pressure is not required. By using these pressure conditions, compared to using high pressure levels of 3.0 MPa to 6.0 MPa in conventional heating bar type equipment, the adhesion strength during lamination is not reduced, while the air permeability of the separator is improved. When the air permeability of the separator is improved in this way, the performance of a battery product including the stack cells according to the present embodiment can be improved.

[0087] By using this merge-type induction heating, the heat from the induction heating section directly heats the foil layer of each stack cell, and since uniform heat conduction is possible due to the heat generated by the foil layer itself, it is not subject to limitations on compression density. Therefore, the required adhesion specifications can be achieved even at low pressure in the induction heating section. Here, the foil layer may refer to a current collector coated with an electrode composite layer included in the electrode within the stack cell.

[0089] Figure 9 is a graph showing the temperature deviation at the completion of heating when a stack cell is manufactured using a heating press device according to the comparative example of Figure 3.

[0090] Referring to FIG. 9, in the case of the heating press method, there may be a temperature difference (D1) at the time when the heating press part completes heating of the inner layer of the cell that is not in contact with the outer layer of the cell that is in contact with the heater. In other words, the convergence temperatures of the outer layer of the cell and the inner layer of the cell may be different from each other.

[0091] FIG. 10 is a graph showing a cell temperature profile in a stack cell manufacturing method according to another embodiment of the present invention.

[0092] Referring to FIGS. 8 and 10, the step of induction heating a stack cell can proceed with the heating by dividing the output of the induction heating into multiple stages in order to control the heating profile and convergence temperature of the inner layer of the stack cell and the outer layer of the stack cell to an equivalent level. For example, as shown in FIG. 10, the multiple stages of the induction heating output can be formed into three stages. Here, the equivalent level may mean a range of ±10% relative to the target temperature.

[0093] Referring to FIG. 8, Step 1 is a section where the temperature rises rapidly, Step 2 is a section where the temperature falls or is maintained, and Step 3 may be a section where the temperature falls and is maintained. According to the present embodiment, dividing the output of the induction heating into at least three sections to proceed with the temperature rise may be a process of reducing the temperature gap between the maximum temperature and the minimum temperature.

[0094] Specifically, the output of Step 1 above can be managed such that the maximum temperature rise over time is maximized, and the cell temperature of each part of the coil section is measured so that the highest temperature among them does not exceed the melting temperature of the separator. For example, as shown in FIG. 10, the cell temperature of five parts of the coil section can be measured.

[0095] The output in Step 2 above can be set lower than the output in Step 1 above, and can be set so that the gap between the high temperature part and the low temperature part is reduced. The output in Step 3 above can be set to further reduce the temperature gap reduced in Step 2.

[0096] Unlike the comparative example shown in Fig. 9, three sections can be set to match the convergence temperatures of the cell outer layer and the cell inner layer, thereby making the outputs different from each other. For example, the output of Step 1 may be the largest, the output of Step 3 may be the smallest, and the output of Step 2 may be a value between the output of Step 1 and the output of Step 3.

[0098] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention. Explanation of the symbols

[0099] 100: Stack cell 200: First induction heating unit 210: First coil assembly 210E, 310E: Input section 210D, 310D: Output section 250: First plate 300: Second induction heating unit 310: Second coil assembly 310a: First coil section 310b: Second coil section 330: Connection 350: Second plate 500: Press section ACP: 2-layer coil section

Claims

Claim 1 A stack cell manufacturing device comprising a stack cell including an anode, a cathode, and a separator interposed between the anode and the cathode, the device comprising an induction heating unit for induction heating the stack cell, wherein the induction heating unit comprises two adjacent coil sections among a plurality of coil sections, wherein the direction in which the induction current moves in the two adjacent coil sections is the same, wherein the induction heating unit comprises an input section into which the induction current is input and an output section into which the induction current is output, wherein the induction heating unit comprises a first coil section connected to the input section and a second coil section connected to the output section, wherein the first coil section and the second coil section are adjacent to each other to form the two adjacent coil sections, and wherein the first coil section and the second coil section are arranged on the same plane. Claim 2 In claim 1, the input part is a stack cell manufacturing device connected in a vertical direction to one of the coil parts of the two layers of coil parts. Claim 3 delete Claim 4 In paragraph 2, the first plane in which the first coil portion and the second coil portion are arranged is a stack cell manufacturing device arranged perpendicular to the stacking direction of the stack cell. Claim 5 In paragraph 2, the input portion is arranged on a second plane having a different level from the first plane in which the first coil portion is arranged, and the output portion is arranged on the second plane, and one of the input portion and the output portion arranged on the second plane intersects the two-layer coil portion arranged on the first plane, a stack cell manufacturing device. Claim 6 A stack cell manufacturing device according to claim 5, wherein the two-layer coil portion is disposed between the input portion and the stack cell. Claim 7 In claim 1, the induction heating unit comprises a stack cell manufacturing device including a plate containing the two-layer coil unit and the two-layer coil unit. Claim 8 In claim 7, the above plate is a stack cell manufacturing device formed of epoxy material. Claim 9 In claim 1, the induction heating unit comprises a first induction heating unit and a second induction heating unit located at the bottom and top of the stack cell, respectively, and the two-layer coil portion included in the first induction heating unit and the two-layer coil portion included in the second induction heating unit have the same direction of movement of the induction current, forming a stack cell manufacturing device. Claim 10 A method for laminating a stack cell comprising an anode, a cathode, and a separator interposed between the anode and the cathode, comprising the steps of: arranging an induction heating unit comprising an input portion into which an induction current is input and an output portion into which the induction current is output on the stack cell; arranging two layers of coil portions, each comprising a first coil portion connected to the input portion and a second coil portion connected to the output portion, which are adjacent to each other and included in the induction heating unit, so as to be arranged on the same plane; and inducing heating the stack cell while the induction current moves in the same direction in the adjacent two layers of coil portions. Claim 11 A method for manufacturing a stack cell according to claim 10, wherein, in the step of induction heating, an input portion into which the induction current is input is connected in a vertical direction to one of the coil portions of the two layers, thereby forming a spaced-apart space between the input portion and the stack cell. Claim 12 A method for manufacturing a stack cell according to claim 11, wherein the two-layer coil portion is disposed in a spaced-apart between the input portion and the stack cell, such that the induced current flowing in the input portion and the induced current flowing in the two-layer coil portion intersect each other. Claim 13 A method for manufacturing a stack cell according to claim 10, wherein one edge of the induction heating part is positioned such that it is spaced apart from the edge of the stack cell by a range of 2 mm or less. Claim 14 A method for manufacturing a stack cell according to claim 10, wherein a magnetic field penetrates the interior of the stack cell by the induction heating above, thereby transferring heat to the cell inside the stack cell. Claim 15 A method for manufacturing a stack cell according to claim 10, further comprising the step of simultaneously pressurizing the stack cell in the step of induction heating the stack cell. Claim 16 A method for manufacturing a stack cell according to claim 15, wherein, in the step of induction heating the stack cell, the peak temperature is managed to reach a range from a temperature 50 degrees Celsius lower than the melting temperature of the separator contained in the stack cell to the melting temperature of the separator. Claim 17 In claim 16, a method for manufacturing a stack cell in which the pressure applying the stack cell is managed in the range of 1.0 MPa to 3.0 MPa. Claim 18 In claim 15, the step of induction heating the stack cell comprises a stack cell manufacturing method in which the output of the induction heating is divided into multiple stages to proceed with the heating, in order to control the heating profile and convergence temperature of the inner layer of the stack cell and the outer layer of the stack cell to an equal level.

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