Secondary battery manufacturing apparatus and secondary battery manufacturing method using the same

Abstract

The present invention relates to an apparatus for manufacturing a secondary battery and a method for manufacturing a secondary battery using the same, and more particularly to an apparatus for manufacturing a secondary battery capable of improving unbonded areas of an electrode and a separator within an electrode unit and an unbonded area of ​​an electrode unit and a separator sheet within an electrode assembly, and a method for manufacturing a secondary battery using the same. The present invention provides an apparatus for manufacturing a secondary battery including a pressurizing unit which pressurizes a stack in which electrodes and separators are alternately arranged, the pressurizing unit including: a main pressurizing unit which pressurizes an entire surface of the stack; and a sub-pressurizing unit having a drum unit which presses a portion of the entire surface of the stack where an edge portion of an electrode active material layer provided on the electrode is located; the drum unit includes a body portion having a rotating shaft; and an elastic portion provided on an outer circumferential surface of the body portion and which presses the portion of the stack.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0124357 filed on September 16, 2021, and Korean Patent Application No. 10-2022-0115228 filed on September 13, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to an apparatus for manufacturing a secondary battery and a method for manufacturing a secondary battery using the same, and more particularly to an apparatus for manufacturing a secondary battery capable of improving unbonded areas of electrodes and separators in an electrode unit and unbonded areas of electrode units and separator sheets in an electrode assembly, and a method for manufacturing a secondary battery using the same. [Background technology]

[0003] Batteries generate electrical energy through physical or chemical reactions of materials and supply power to the outside world. They are used in living environments where AC power cannot be obtained from the building or DC power is required due to living environments surrounded by various electrical and electronic devices.

[0004] Among these batteries, primary and secondary batteries, which are chemical batteries that utilize chemical reactions, are commonly used. Primary batteries, commonly known as dry batteries, are consumable batteries. Secondary batteries are rechargeable batteries made using materials that can undergo a redox process between current and materials multiple times. When a reduction reaction occurs in the material due to current, the power source is charged, and when an oxidation reaction occurs in the material, the power source is discharged. Electricity is generated by repeating this charge-discharge cycle.

[0005] Here, in the case of a lithium ion battery, among secondary batteries, an electrode is manufactured by coating a positive electrode conductive foil and a negative electrode conductive foil with an electrode slurry, which is a mixture of an active material, a conductive material, and a binder, to a predetermined thickness, and an electrode unit can be manufactured by interposing a separator between the two conductive foils.

[0006] Secondary batteries can also be classified by structure. For example, they can be classified into cylindrical secondary batteries, which are manufactured by winding a long sheet-like electrode unit multiple times into a jelly roll shape with a separator sheet interposed therebetween to manufacture an electrode assembly, placing the manufactured electrode assembly in a cylindrical can, etc., and sealing it; and pouch secondary batteries, which are manufactured by folding electrode units of a predetermined size so that they are stacked with a separator sheet interposed therebetween to manufacture an electrode assembly, placing the manufactured electrode assembly in a pouch, and sealing it.

[0007] Meanwhile, during electrode manufacturing, the viscosity of the electrode slurry can cause uneven application of the electrode slurry to the conductive foil, resulting in uneven coating thickness of the electrode slurry. Such uneven coating thickness of the electrode slurry can result in unbonded areas between the electrode and the separator within an electrode unit manufactured including the electrode. Furthermore, since pouch-type secondary batteries are manufactured by stacking electrode units on a separator sheet, unbonded areas are formed within the electrode assembly including the electrode unit. Such unbonded areas can cause lithium deposition due to interfacial resistance of the negative electrode, thereby increasing the resistance of the electrode. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide an apparatus and a method for manufacturing a secondary battery that can improve unbonded areas of electrodes and separators in an electrode unit and unbonded areas of electrode units and separator sheets in an electrode assembly. [Means for solving the problem]

[0009] The present invention provides a secondary battery manufacturing apparatus including a pressurizing unit that pressurizes a stack in which electrodes and separators are alternately arranged, wherein the pressurizing unit includes a main pressurizing unit that presses an entire surface of the stack; and a sub pressurizing unit having a drum unit that presses a portion of the entire surface of the stack where an edge portion of an electrode active material layer provided on the electrode is located; the drum unit may include a body having a rotation axis; and an elastic unit provided on an outer peripheral surface of the body and pressing the portion of the surface of the stack.

[0010] The edge portions of the electrode active material layers may be curved so that their heights decrease toward the ends, and the drum unit may apply pressure to adhere the corresponding edge portions of the electrode active material layers to the separator.

[0011] The elastic portion may be provided to be elastically deformable.

[0012] The elastic part may have an internal space formed therein, and the internal space may be filled with air or a fluid to maintain a preset pressure.

[0013] The elastic portion may be made of a deformable synthetic resin, and the synthetic resin may be made of silicone rubber.

[0014] The sub-pressure portion may be deformed in shape only when the partial surface is pressed.

[0015] The secondary battery manufacturing apparatus may include a pressure detection unit that detects the pressure with which the sub-pressurizing unit presses the partial surface of the stack.

[0016] The pressure detection unit may include a sensor unit that senses pressure; and a display unit that displays the pressure sensed by the sensor unit.

[0017] The sensor unit may be disposed opposite the sub-pressure unit across the partial surface of the laminate.

[0018] The laminate may include electrode tabs connected to the electrodes; and the sub-pressurizing unit may press a portion of the laminate surface to which the electrode tabs are connected and on which an edge portion of an electrode active material layer provided on the electrode is located.

[0019] The sub-pressure unit may be disposed at least either in front of or behind the main pressure unit.

[0020] The secondary battery manufacturing apparatus may include a heating unit disposed after the pressurizing unit to apply heat to the stack in which the electrodes and the separator are stacked; and the sub-pressurizing unit may be disposed between the heating unit and the main pressurizing unit.

[0021] The edge portions may be provided at both ends of an electrode active material layer provided on the electrode, and a pair of drum portions may be provided to pressurize only a portion of a surface of the laminate where the edge portions provided at both ends of the electrode active material layer are located.

[0022] The edge portions may be provided at both ends of an electrode active material layer provided on the electrode, and the drum unit may press a surface including a portion of the laminate where the edge portions provided at both ends of the electrode active material layer are located.

[0023] The sub-pressurizing unit may further include a pressure sensor that measures the pressure of air or fluid filled in the internal space of the elastic unit.

[0024] The sub-pressurizing unit may further include an injection unit configured to inject air or a fluid into the internal space of the elastic unit through the body unit.

[0025] Meanwhile, the present invention provides a method for manufacturing a secondary battery, the method including: an electrode unit manufacturing step of manufacturing electrode units each having an electrode and a separator disposed therein; an electrode assembly manufacturing step of manufacturing an electrode assembly by disposing a separator sheet between a plurality of electrode units manufactured in the electrode unit manufacturing step; and an electrode assembly pressurizing step of pressurizing the electrode assembly, wherein the electrode unit manufacturing step includes a stacking step of alternately arranging the separators and the electrodes to form a stack; and a bonding step of bonding the separators and the electrodes included in the stack; the bonding step may include an entire surface pressing step of pressing an entire surface of the stack; and a first partial surface pressing step of pressing a partial surface of the stack where an edge portion of an electrode active material layer provided in the electrode is located, among the entire surface.

[0026] The electrode assembly pressing step may include a second entire surface pressing step of pressing an entire surface of the electrode assembly; and a second partial surface pressing step of pressing a partial surface of the electrode assembly where an edge portion of an electrode active material layer provided on the electrode is located among the entire surface of the electrode assembly. [Effects of the Invention]

[0027] The secondary battery manufacturing apparatus and the secondary battery manufacturing method using the same according to the present invention have the advantage that unbonded areas within the laminate can be improved by using a sub-pressure unit to pressurize a portion of the entire surface of the laminate where an edge portion of an electrode active material layer provided on an electrode of the laminate is located.

[0028] In addition, the secondary battery manufacturing apparatus according to the present invention has the advantage that it can accommodate various sizes and shapes of a portion of the entire surface of the laminate without changing the sub-pressure unit by using a sub-pressure unit including an elastic unit.

[0029] Furthermore, by including a pressure detection unit, the secondary battery manufacturing apparatus according to the present invention has the advantage of being able to detect the pressure with which the sub-pressurizing unit pressurizes the stack, and to easily manage processability according to the stack model and process environment based on the detected pressure. [Brief explanation of the drawings]

[0030] [Figure 1a] 1 is a perspective view showing a laminate of the present invention. [Figure 1b] FIG. 1b is a side view showing the laminate of FIG. 1a as seen from the side. [Figure 2] 1 is a plan view showing a secondary battery manufacturing apparatus according to an embodiment of the present invention as viewed from above. [Figure 3] 3 is a side view showing the secondary battery manufacturing apparatus of FIG. 2 as seen from the side. FIG. [Figure 4a] 3 is a side view showing in more detail the side surface of a sub-pressure unit in the secondary battery manufacturing apparatus of FIG. 2. FIG. [Figure 4b] 3 is a front view showing a drum part of a sub-pressure unit in the secondary battery manufacturing apparatus of FIG. 2. FIG. [Figure 4c] 3 is a side view showing a drum part of a sub-pressure unit in the secondary battery manufacturing apparatus of FIG. 2. FIG. [Figure 5a] 3 is an enlarged view showing in more detail how an elastic portion in the secondary battery manufacturing apparatus of FIG. 2 presses a laminate of one shape. [Figure 5b] 3 is an enlarged view showing in more detail how an elastic portion in the secondary battery manufacturing apparatus of FIG. 2 presses a stack having another shape. [Figure 5c] 3 is an enlarged view showing in more detail how the elastic portion in the secondary battery manufacturing apparatus of FIG. 2 presses a stack having another shape. [Figure 5d] 10 is an enlarged view showing in more detail how a sub-pressure unit of another embodiment in the secondary battery manufacturing apparatus of FIG. 2 presses a stack. FIG. [Figure 6] 3 is a perspective view showing in more detail the sub-pressurizing unit and the pressure detecting unit in the secondary battery manufacturing apparatus of FIG. 2. FIG. [Figure 7] 1A and 1B are images showing the formation of unbonded regions in bi-cells manufactured by a conventional secondary battery manufacturing apparatus (a) and a secondary battery manufacturing apparatus according to the present invention (b). DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily understand the preferred embodiments of the present invention. However, the present invention can be realized in various different forms and is not limited to the following embodiments.

[0032] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention will be omitted, and when adding reference symbols to components in each drawing in this specification, the same or similar reference symbols will be used for the same or similar components throughout the specification.

[0033] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of the present invention, based on the principle that an inventor can appropriately define the concept of a term in order to explain his or her invention in the best possible way.

[0034] The present invention can provide a secondary battery manufacturing apparatus including a pressurizing unit 100 that pressurizes a stack 10 in which electrodes 101 and separators 102 are stacked.

[0035] First, the laminate 10 is configured by stacking electrodes 101 and separators 102, and may have various configurations. Here, the laminate 10 refers to an electrode unit, i.e., a unit cell, in which electrodes 101 and separators 102 are stacked, and may refer to any one of a bi-cell, a mono-cell, and a full-cell, or may refer to an electrode assembly in which a plurality of electrode units (unit cells) in which electrodes 101 and separators 102 are stacked, and a separator sheet 20 are stacked.

[0036] Referring to FIG. 1b, the electrode 101 includes an electrode current collector 1011 and an electrode active material layer 1012 coated on the surface of the electrode current collector 1011.

[0037] Here, the electrode assembly may have any structure as long as it has a structure in which a plurality of electrode units and a separator sheet are stacked. For example, the electrode assembly may have a structure in which a plurality of electrode units are arranged or lined up on a separator sheet. For another example, the electrode assembly may have a structure in which a plurality of electrode units are arranged or lined up on a separator sheet, and then the electrode units and the separator sheet are alternately stacked and folded.

[0038] Here, the laminate 10 may be pressed by a pressurizing unit 100 (described later) to bond the electrodes and the separator, and the electrode unit and the separator sheet together. In this case, the entire surface of the laminate 10 that faces the pressurizing unit 100 and is pressed is defined as an entire surface 11.

[0039] Meanwhile, as described above, the electrode slurry is unevenly applied to the electrode current collector (e.g., conductive foil) on the entire surface 11, resulting in height differences. In particular, the surface of the entire surface 11 that is relatively low in height is difficult to pressurize during the pressing process, leaving an unbonded region where the electrode-separator or electrode unit-separator sheet are not bonded, which can cause lithium deposition on the interface of the negative electrode.

[0040] 1a and 1b, the overall surface 11 includes a first surface 12, which includes a surface formed with a relatively low height among the overall surface 11 of the laminate 10, and a second surface 13, which is formed with a constant height by uniformly applying electrode slurry onto an electrode current collector. Meanwhile, the dotted lines shown on the laminate 10 in the drawings are used to separate the first surface 12 and the second surface 13, and do not mean that the internal structure of the laminate 10 is separated.

[0041] Here, the partial surface 12 is a surface including a surface formed with a relatively low height among the entire surface 11 of the laminate 10 due to insufficient application of electrode slurry on the electrode current collector, and various configurations are possible.

[0042] As an example, the partial surface 12 is a surface having a difference in height, and includes a first partial surface 12a having a relatively lower height than the entire surface 11, and a second partial surface 12b having a higher height than the first partial surface 12a, as shown in FIG. 1b.

[0043] Here, the first partial surface 12a may be a surface formed with a relatively low height among the entire surface, and may be a surface of the laminate 10 where an edge portion 1013 of an electrode active material layer 1012 provided on the electrode 101 is located among the entire surface 11. Meanwhile, the edge portion 1013 of the electrode active material layer 1012 is formed into a curved surface that decreases in height toward the end as electrode slurry flows down, and the surface of the laminate 10 where the edge portion is located has a lower height than the curved edge portion 1013. Therefore, the edge portions 1013 of the electrode active material layers 1012 and the separators 102 corresponding to each other remain unattached. A technical feature of the present invention is that the edge portions 1013 of the electrode active material layers 1012 and the separators 102, which are not yet attached to each other, are bonded together.

[0044] In addition, the second surface 12b is a surface formed higher than the first surface 12a, and is formed in various directions based on the first surface 12a depending on the size of each model of the laminate 10 and the degree to which the electrode slurry in the laminate 10 is unevenly applied.

[0045] For example, as shown in Fig. 1b, the second surface 12b may be formed between the first surface 12a and the second surface 13. However, the second surface 12b is not limited to this and may be formed in various ways, such as being surrounded by the first surface 12a or being formed to surround the first surface 12a.

[0046] As another example, the partial surface 12 may be formed only by the first partial surface 12a formed to have a relatively low height among the entire surface 11.

[0047] Meanwhile, the partial surface 12 may be located at any position of the laminate 10 .

[0048] For example, as the length of the laminate 10 increases, the electrode slurry reaches less of the edge of the electrode current collector when the electrode slurry is applied, so that the partial surface 12 is located in correspondence with the edge of the laminate 10 .

[0049] In particular, the partial surface 12 is located in an edge region of the laminate 10 corresponding to the edge region of the laminate 10 where the electrode tab 14 is located.

[0050] This is understood to be because, when manufacturing electrodes, if electrode slurry is applied to the center of one electrode current collector, dried, and then the center is cut to manufacture two electrodes, it is expected that the electrode slurry will be sufficiently applied to the edge region of the laminate 10, which was the center of the original electrode current collector, but it is relatively difficult for the electrode slurry to reach the edge region of the electrode current collector where the electrode tab 14 is located.

[0051] Here, the electrode tab 14 may be formed on the electrode current collector by a notching process before the electrode slurry is coated, or may be connected to the electrode by being attached to any part of the electrode current collector after the electrode slurry is coated.

[0052] On the other hand, the pressure unit 100 is configured to apply pressure to the laminate 10, and various configurations are possible.

[0053] Specifically, the pressing unit 100 according to the present invention may include a main pressing unit 110 that presses the entire surface 11 of the laminate 10; and a sub-pressing unit 120 that presses a portion 12 of the laminate 10, as shown in FIGS. 2 and 3.

[0054] Here, the main pressure unit 110 is configured to apply pressure to the entire surface 11 of the laminate 10, and various configurations are possible.

[0055] For example, the main pressure unit 110 may be configured with a roller that applies pressure to the laminate 10 while rotating it, or a press that applies pressure to the laminate 10 while moving it in the vertical direction.

[0056] Here, when the laminate 10 is an electrode unit, the main pressure unit 110 may be provided as a roller, and when the laminate 10 is an electrode assembly, the main pressure unit 110 may be provided as a press.

[0057] Meanwhile, the sub-pressure unit 120 is configured to pressurize one surface 12 of the laminate 10, and can have various configurations.

[0058] More specifically, the sub-pressurizing unit 120 may be disposed at least one of in front of and behind the main pressing unit 110 and may press a partial surface 12 of the laminate 10 before and / or after pressing the entire surface 11 of the laminate 10. Thus, the sub-pressurizing unit 120 may press the partial surface 12 where the edge portion 1013 of the electrode active material layer 1012 provided on the electrode 101 is located, thereby bonding the unbonded regions of the laminate 10, i.e., the edge portion 1013 of the electrode active material layer and the unbonded region of the separator 102, which correspond to each other. Meanwhile, the direction toward the moving direction of the laminate 10 on the conveyor belt is referred to as the front, and the opposite direction from the front is referred to as the rear.

[0059] In addition, as shown in FIG. 3, the sub-pressurizing unit 120 may include a drum unit 121 that presses a portion 12 of the entire surface of the laminate 10 where an edge portion 1013 of the electrode active material layer provided on the electrode is located.

[0060] The drum unit 121 is configured to apply pressure to the surface 12 of the laminate 10 while rotating, and may have various configurations.

[0061] More specifically, the laminates 10 are formed in various lengths and widths for each model, and areas where the electrode slurry is applied unevenly are formed irregularly for each laminate 10, so the area of the surface (e.g., the first partial surface 12a) that is formed with a relatively low height among the entire surface 11 of the laminate 10 is formed in various sizes for each individual laminate 10.

[0062] If the drum part 121 of the sub-pressure unit 120 is made of a hard material (e.g., steel) and is unable to deform when pressing the partial surface 12, the drum part 121 will be unable to accommodate various sizes and shapes of the surface 11 that is relatively low in height. This causes the user to have to take this into consideration and change the sub-pressure unit 120 every time, which is a hassle.

[0063] Therefore, in the present invention, the drum unit 121 is configured to be able to respond to various changes in the partial surface 12 of the laminate where the edge portion 1013 of the electrode active material layer is located among the entire surface 11 of each laminate 10, without replacing the sub-pressure unit 120 or the drum unit 121 configured in the sub-pressure unit 120, and the drum unit 121 will be described in detail below.

[0064] Here, as shown in FIGS. 4a to 4c, the drum part 121 may include a body part 121a having the rotation shaft 122, and an elastic part 121b fixedly coupled along the outer circumferential surface of the body part 121a and elastically deformable.

[0065] Here, the body portion 121a is configured to be coupled with the rotary shaft 122, and various configurations are possible.

[0066] 5a, when the body part 121a of the drum part 121 rotates around the rotating shaft 122, the elastic part 121b rotates in conjunction with the body part 121a, thereby pressing the surface 12 of the laminate 10 where the edge part 1013 of the electrode active material layer is located. Here, the elastic part 121b deforms according to the shape of the laminate 10, which deforms when the surface 12 of the laminate 10 is pressed, thereby stably pressing the entire surface 12 of the laminate 10, and in particular, bonding the edge part 1013 of the electrode active material layer and the unbonded region of the separator 102.

[0067] More specifically, the body part 121a is configured to rotate the drum part 121 by the rotational force transmitted from the rotation shaft 122, and may have various shapes. For example, the body part 121a may have a cylindrical shape, a wheel shape with a plurality of spokes, etc.

[0068] Here, the elastic part 121b is fixedly coupled along the outer circumferential surface of the body part 121a and is elastically deformable, and may have various configurations.

[0069] 4a to 4c, the elastic part 121b has an internal space 121c formed therein, and the internal space 121c is filled with air or a fluid to maintain a preset pressure. For example, the elastic part 121b has the shape of a bicycle wheel filled with air.

[0070] Hereinafter, a more detailed description will be given of the case where the elastic portion 121b responds to various changes in the partial surface of the laminate where the edge portion of the electrode active material layer is located among the entire surface 11. Here, the width of the partial surface 12, the width of the first partial surface 12a, and the width of the drum portion 121, which will be described later, are understood as widths whose length direction is the direction in which the laminate 10 moves on the conveyor belt.

[0071] Specifically, since the elastic portion 121b is made of an elastic material that allows the shape of the pressure surface to be deformed when pressure is applied to the surface 12, the drum portion 121 can respond to various changes in the surface 12 of the laminate 10 where the edge portion 1013 of the electrode active material layer is located among the entire surface 11.

[0072] 5a, when the drum unit 121 presses the surface of the laminate where the edge of the electrode active material layer 1012 is located, the elastic unit 121b presses the surface 12, and the pressing surface of the elastic unit 121b deforms to have a step corresponding to the shape of the surface 12. Thus, the sub-pressure unit 120 can press the entire surface 12, including the first surface 12a and the second surface 12b.

[0073] 5b, in the case of a laminate 10 in which two electrode tabs 14 are drawn out in opposite directions of the electrode, edge portions 1013 of an electrode active material layer 1012 may be provided at both ends of the electrode active material layer provided on the electrode, and a pair of drum units 121 may be provided to pressurize respective portions of the surface 12 of the laminate 10 where the edge portions 1013 provided at both ends of the electrode active material layer are located. In other words, the pair of drum units 121 may pressurize respective portions of the surface 12 located on both sides of the laminate.

[0074] In particular, when the width of the surface 12 of the elastic portion 121b is formed to be larger than the width of the drum portion 121, the pressure application surface of the elastic portion 121b expands in the width direction of the surface 12, thereby applying pressure to all parts of the surface 12.

[0075] 5c, in the case of a laminate 10 in which two electrode tabs 14 are extended in both directions of the electrode, the drum unit 121 may pressurize the entire surface of the laminate 10, including a portion 12 of the laminate 10 where the edge portions 1013 provided at both ends of the electrode active material layer are located. In other words, one drum unit 121 may pressurize the entire surface of the laminate, including a portion of the laminate where the edge portions are located.

[0076] As another example, as shown in FIG. 5d, the sub-pressurizing units may be disposed corresponding to the upper and lower surfaces of the laminate 10, respectively, to simultaneously pressurize the upper and lower portions of the surface 12 of the laminate. Here, the sub-pressurizing unit disposed at the lower portion of the laminate is referred to as the lower sub-pressurizing unit 120", and the sub-pressurizing unit disposed at the upper portion of the laminate is referred to as the upper sub-pressurizing unit 120'. That is, with the lower sub-pressurizing unit 120" supported on the lower portion of the surface 12 of the laminate 10, the upper sub-pressurizing unit 120' presses the upper portion of the surface 12 of the laminate. In this way, the surface of the laminate located between the upper and lower sub-pressurizing units is pressed, and as a result, the surface of the laminate 10 where the edge portions 1013 provided at both ends of the electrode active material layer are located can be more effectively pressed.

[0077] Meanwhile, the elastic portion 121b may be made of various elastically deformable materials. For example, the elastic portion 121b may be made of a deformable synthetic resin, and the synthetic resin may be made of a material including any one of silicone rubbers.

[0078] Meanwhile, the elastic portion 121b of the sub-compressor 120 may be deformed only when the partial surface is compressed. The elastic portion 121b may have various structures.

[0079] As an example, the elastic portion 121b may have a pad structure having a predetermined thickness and made of only an elastic material, and as another example, the elastic portion 121b may have a tire structure in which an internal space is formed and the internal space is filled with air or fluid to maintain a preset pressure.

[0080] Here, the preset pressure may be a predetermined pressure value that allows the elastic portion 121b to be elastically deformed when the partial surface 12 is pressed.

[0081] In this case, the pre-set pressure can be set in various ways by the user depending on the material and size of the elastic portion 121b, and it goes without saying that the pressure value with which the sub-pressure unit 120 presses one surface 12 of the laminate 10 can be fed back by the pressure detection unit 300 described later to adjust the pressure.

[0082] In addition, the sub-compressor 120 may further include a pressure sensor 123 for measuring the pressure of air or fluid filled in the internal space of the elastic part 121b. The pressure sensor 123 may be installed in a through-hole formed in the body 121a and connected to the inside of the elastic part 121b. This makes it easy to check the internal pressure of the elastic part 121b from the outside.

[0083] In addition, the sub-compressor 120 may further include an injector 124 for injecting air or a fluid into the internal space of the elastic portion 121b through the body 121a. As a result, when the internal pressure of the elastic portion 121b becomes low or high, the pressure can be maintained constant by injecting or discharging air through the injector 124. Meanwhile, the sub-compressor 120 may have any configuration as long as it is configured to deform when one surface 12 is compressed, and is not limited to the configuration including the elastic portion 121b described above.

[0084] Meanwhile, the rotary shaft 122 is configured to be coupled with the drum part 121 to rotate the drum part, and various configurations are possible.

[0085] For example, one end of the rotating shaft 122 may be connected to a driving motor to transmit the rotational force, and the rotational force of the driving motor may be transmitted to the body portion 121a. Also, the rotating shaft 122 may include a bearing (not shown) provided between the rotating shaft 122 and the body portion 121a to surround the outer circumferential surface of the rotating shaft 122.

[0086] Meanwhile, the secondary battery manufacturing apparatus according to the present invention may further include a pressure detection unit 300 as shown in FIG.

[0087] Here, the pressure detection unit 300 is configured to detect the pressure applied by the sub-pressure unit 120 to the one surface 12 of the laminate 10, and may have various configurations.

[0088] In other words, the user of the secondary battery manufacturing apparatus according to the present invention has the advantage that, by detecting the pressure applied by the sub-pressurizing unit 120 to the stack 10 using the pressure detection unit 300, the user can manage the processability for each model of the stack 10 and each process environment using data regarding the pressure applied for each model of the stack 10 and each process environment.

[0089] Meanwhile, the pressure detection unit 300 may be disposed at various positions. For example, the pressure detection unit 300 may be disposed below the conveyor belt at a position corresponding to the sub-pressurizing unit 120.

[0090] 6, the pressure detection unit 300 may include a sensor unit 310 for detecting pressure and a display unit 320 for displaying the pressure detected by the sensor unit 310.

[0091] Here, the sensor unit 310 is configured to sense pressure and can have various configurations.

[0092] That is, the sensor unit 310 may include a mechanical, electronic, or semiconductor pressure sensor for sensing pressure, and various pressure sensors can be used depending on the required pressure range and pressure measurement environment.

[0093] The sensor unit 310 may be disposed at various positions. However, the sensor unit 310 is preferably disposed opposite the sub-pressure unit 120 across the surface 12 of the laminate 10, as shown in Fig. 6, in order to measure the pressure applied to the surface 12 when the sub-pressure unit 120 presses the surface 12. That is, the sensor unit 310 may be disposed on a line through which the surface 12 of the laminate 10 passes.

[0094] Meanwhile, the display unit 320 is configured to display the pressure sensed by the sensor unit 310, and may have various configurations.

[0095] That is, the display unit 320 may have any configuration that provides the user with data regarding the pressure sensed by the sensor unit 310, and may include, for example, a display device that outputs the data regarding the pressure as an image.

[0096] Meanwhile, the secondary battery manufacturing apparatus according to the present invention may further include a heating unit 200 for applying heat to the stack 10 in which the electrodes and the separator are stacked.

[0097] Here, the heating unit 200 is disposed behind the pressing unit 100 and is configured to apply heat to the laminate 10 in which the electrodes and the separator are stacked, and may have various configurations. As described above, the term "rear" may refer to a direction opposite to the direction in which the laminate 10 travels on the conveyor belt.

[0098] More specifically, the heating unit 200 may be disposed behind the pressure unit 100 and may apply heat to the laminate 10 before the pressure unit 100 applies pressure to the laminate 10. That is, as the temperature of the laminate 10 increases, the adhesive strength between the electrodes and the separator may be improved, and wrinkles formed in the electrodes, separator, separator sheet, etc. within the laminate during the manufacturing process may be improved.

[0099] In this case, the laminate 10 may be heated to a temperature above room temperature. Here, room temperature refers to the temperature range known in the art as "room temperature" or normal temperature. That is, it refers to the temperature in a laboratory or research lab, and is an expression of temperature conditions used when conducting an experiment without specifying or adjusting the temperature or when samples and materials are left indoors, and refers to the indoor air temperature. Generally, room temperature is a temperature at which humans can feel comfortable, usually around 15°C to 20°C.

[0100] Meanwhile, the sub-pressurizing unit 120 may be disposed in various positions as described above. However, when the sub-pressurizing unit 120 presses a portion of the surface 12 while the laminate 10 is heated, the unbonded areas inside the laminate 10 can be more effectively improved. Therefore, it is preferable that the sub-pressurizing unit 120 be disposed between the heating unit 200 and the main pressing unit 110, as shown in FIGS. 2 and 3.

[0101] A secondary battery manufacturing method using the secondary battery manufacturing apparatus of the present invention will be described below.

[0102] Meanwhile, the present invention provides a method for manufacturing a secondary battery, including: an electrode unit manufacturing step of manufacturing an electrode unit in which electrodes and a separator are stacked; an electrode assembly manufacturing step of manufacturing an electrode assembly in which a plurality of electrode units manufactured in the electrode unit manufacturing step and a separator sheet are stacked; and an electrode assembly pressurizing step of pressurizing the electrode assembly.

[0103] Here, the electrode unit manufacturing step is a step of manufacturing an electrode unit in which the electrode 101 and the separator 102 are stacked, and can be performed in various ways.

[0104] For example, the electrode unit manufacturing step may include a laminating step of laminating the electrode 101 on the separator 102 to prepare a laminate 10; and a bonding step of bonding the separator and the electrode in the laminate 10.

[0105] Here, the lamination step is a step of laminating the electrode 101 on the separator 102 to prepare the laminate 10, and can be performed in various ways.

[0106] The electrode 101 includes an electrode current collector 1011 and an electrode active material layer 1012 coated on the electrode current collector 1011. That is, the electrode 101 can be manufactured as a positive or negative electrode by applying an electrode slurry onto the electrode current collector (conductive foil) 1011 and then coating the electrode current collector 1011, and can be manufactured by stacking the electrodes with a separator interposed between them. However, during the electrode manufacturing process, the electrode slurry may be unevenly coated on the electrode current collector. That is, the edge portion 1013 of the electrode active material layer 1012 coated on the electrode is irregularly coated with the electrode slurry, and as a result, the edge portion 1013 of the electrode active material layer 1012 is formed into a curved surface whose height decreases toward the end.

[0107] Meanwhile, the bonding step is a step of bonding the separator and the electrode in the laminate, and can be performed in various ways.

[0108] For example, the bonding step may include a first entire surface pressing step of pressing the entire surface of the laminate 10; and a first partial surface pressing step of pressing a partial surface 12 of the laminate where a height difference is formed.

[0109] Here, the first entire surface pressing step is a step of pressing the entire surface 11 of the laminate 10, and can be performed in various ways.

[0110] In this case, the first entire surface pressing step may be performed by pressing the entire surface 11 of the laminate 10 using the main pressing unit 110. However, since the electrode slurry is unevenly coated on the electrode current collector, which causes height differences across the entire surface of the laminate 10, an unbonded area may occur on a portion 12 of the laminate where an edge portion of the electrode active material layer is located (see FIG. 1b).

[0111] Meanwhile, the first partial surface pressing step is a step of pressing the partial surface 12 of the laminate 10 where the edge portion 1013 of the electrode active material layer 1012 is located, and can be performed in various ways.

[0112] Specifically, the first partial surface pressing step may be performed by pressing the partial surface 12 of the laminate 10 using the sub-pressure unit 120. Here, the detailed configuration and effects of the sub-pressure unit 120 are as described above.

[0113] That is, the first partial surface pressing step may additionally pressurize the partial surface 12 of the laminate 10, thereby bonding the unbonded region between the edge portion 1013 of the electrode active material layer of the laminate 10 and the separator 102. Here, it goes without saying that the first partial surface pressing step may be performed not only after the first entire surface pressing step but also before the first entire surface pressing step.

[0114] Meanwhile, the electrode assembly manufacturing step is a step of manufacturing an electrode assembly in which a separator sheet is stacked with the plurality of electrode units manufactured in the electrode unit manufacturing step, and can be performed in various ways. Herein, the electrode assembly can also be understood as a configuration corresponding to the above-mentioned stack 10, but will be described hereinafter as an electrode assembly to distinguish it from the above-mentioned electrode units.

[0115] Specifically, the electrode assembly manufacturing step may manufacture an electrode assembly by arranging the electrode units manufactured in the electrode unit manufacturing step in a row on a separator sheet, or by arranging the electrode units in a row on a separator sheet and then folding the separator sheet so that the electrode units and the separator sheet are alternately stacked.

[0116] However, in the case of an electrode unit having an unbonded region between the electrode and the separator, a particular region of the electrode unit is formed to be relatively lower in height than other regions. Therefore, when the electrode units are stacked in parallel in one direction during the manufacture of the electrode assembly, an unbonded region is formed between the electrode unit and the separator sheet, resulting in a surface that is relatively lower in height than the entire surface of the electrode assembly.

[0117] Meanwhile, the step of pressurizing the electrode assembly can be performed in various ways.

[0118] For example, the electrode assembly pressing step may include a second entire surface pressing step of pressing the entire surface of the electrode assembly; and a second partial surface pressing step of pressing a partial surface of the electrode assembly having a height difference formed on its outer surface.

[0119] Here, the second entire surface pressing step is a step of pressing the entire surface of the electrode assembly, and can be performed in various ways.

[0120] Here, the second entire surface pressing step may be performed by pressing the entire surface of the electrode assembly using the main pressing unit 110. However, as described above, since there is a difference in height across the entire surface of the electrode assembly, an unbonded area may occur on some surfaces, including those that are relatively low in height.

[0121] Meanwhile, the second partial surface pressing step is a step of pressing a partial surface having a height difference formed on the outer surface of the electrode assembly, and can be performed in various ways.

[0122] Specifically, the second partial surface pressing step may be performed by pressing a partial surface of the electrode assembly where an edge portion of the electrode active material layer is located using the sub-pressure unit 120. Here, the detailed configuration and effects of the sub-pressure unit 120 are as described above.

[0123] That is, the second partial surface pressing step can improve the unbonded area of the electrode assembly by additionally pressing a portion of the electrode assembly. Here, it goes without saying that the second partial surface pressing step may be performed before the second entire surface pressing step, as well as after the second entire surface pressing step.

[0124] The size of the unbonded area of the laminate depending on whether or not the present invention is applied will be explained below with reference to Fig. 7. Here, the laminate is a bi-cell, and Fig. 7(a) shows a front image of a bi-cell manufactured by conventional technology (hereinafter referred to as "Comparative Example"), and Fig. 7(b) shows a front image of a bi-cell manufactured by the present invention (hereinafter referred to as "Example of the present invention").

[0125] First, in the front view of the bi-cell formed according to the comparative example in Figure 7(a), it can be seen that a black electrode-separator unbonded area is formed at the top of the bi-cell, i.e., at edge B corresponding to the electrode tab. Furthermore, in an electrode assembly including such unit cells, it is expected that an unbonded area will occur between the unit cell and separator sheet, leading to lithium deposition on the negative electrode and an increase in electrode resistance. This can result in a problem of reduced secondary battery performance.

[0126] 7(b), it can be seen that there is almost no unbonded area at the top of the bi-cell, i.e., at edge B corresponding to the electrode tab. Therefore, the electrode unit formed according to the embodiment of the present invention is expected to have almost no unbonded area between the electrode and separator inside the electrode unit, as well as between the unit cell and separator sheet on the electrode assembly. This has the advantage of minimizing lithium deposition due to interfacial resistance on the negative electrode, thereby improving the performance of the secondary battery.

[0127] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and various implementations within the technical spirit of the present invention and the scope of equivalents of the appended claims can be made by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0128] 10 Laminate 11 Overall aspect 12 Partial side 12a Page 1 12b Part 2 13 Other parts 14 Electrode tab 101 Electrode 1011 Electrode current collector 1012 Electrode active material layer 1013 Edge part 102 Separation membrane 20 Separation membrane sheet 100 pressure unit 110 Main pressure section 120 Sub-pressure section 121 Drum Section 121a Torso 121b Elastic part 122 Rotation axis 123 Pressure Sensor 124 Injection part 200 Heating section 300 Pressure detection unit 310 Sensor unit 320 Display

Claims

1. 1. A secondary battery manufacturing apparatus including a pressurizing unit that pressurizes a stack in which electrodes and separators are alternately arranged, The pressure applying unit is a main pressure section that applies pressure to the entire surface of the laminate; and a sub-pressure unit including a drum unit that presses a portion of the surface of the laminate where an edge portion of an electrode active material layer provided on the electrode is located, among the entire surface of the laminate; The drum unit includes: a body having an axis of rotation; and an elastic portion provided on the outer circumferential surface of the body portion and pressurizing a part of the surface of the laminate; The edge portions are provided at both ends of the electrode active material layer provided on the electrode, a pair of drum units are provided to pressurize a portion of a surface of the laminate where the edge units provided at both ends of the electrode active material layer are located, The secondary battery manufacturing apparatus, wherein the sub-pressurizing unit is disposed behind the main pressurizing unit.

2. The edge portion of the electrode active material layer is formed into a curved surface whose height decreases toward the end, The apparatus for manufacturing a secondary battery according to claim 1 , wherein the drum unit applies pressure so that the edge portions of the electrode active material layers and the separators corresponding to each other are adhered to each other.

3. The secondary battery manufacturing apparatus according to claim 2 , wherein the elastic portion is provided to be elastically deformable.

4. The elastic portion has an internal space formed therein, The apparatus for manufacturing a secondary battery according to claim 3 , wherein the internal space is filled with air or a fluid to maintain a preset pressure.

5. the elastic portion is made of a deformable synthetic resin, The secondary battery manufacturing apparatus according to claim 3 , wherein the synthetic resin is made of silicone rubber.

6. The secondary battery manufacturing apparatus according to claim 1 , wherein the sub-pressure unit deforms in shape only when the partial surface is pressurized.

7. The secondary battery manufacturing apparatus includes: The secondary battery manufacturing apparatus according to claim 1 , further comprising a pressure detection unit that detects a pressure applied by the sub-pressurizing unit to the partial surface of the laminate.

8. The pressure detection unit a sensor unit that senses pressure; and The apparatus of claim 7 , further comprising a display unit that displays the pressure sensed by the sensor unit.

9. The secondary battery manufacturing apparatus according to claim 8 , wherein the sensor unit is disposed opposite the sub-pressure unit across a portion of the surface of the laminate.

10. the laminate includes electrode tabs connected to the electrodes; The apparatus of claim 1 , wherein the sub-pressure unit presses a portion of the surface of the laminate where the electrode tab is connected and an edge portion of an electrode active material layer provided on the electrode is located.

11. The secondary battery manufacturing apparatus includes: a heating unit disposed behind the pressure unit to apply heat to the stack in which the electrodes and the separator are stacked; The secondary battery manufacturing apparatus according to claim 1 , wherein the sub-pressure unit is disposed between the heating unit and the main pressure unit.

12. The apparatus of claim 4 , wherein the sub-pressurizing unit further comprises a pressure sensor that measures a pressure of the air or the fluid filled in the internal space of the elastic unit.

13. The apparatus of claim 4 , wherein the sub-pressurizing unit further includes an injection unit configured to inject the air or the fluid into the internal space of the elastic unit through the body unit.

14. 2. The secondary battery manufacturing apparatus according to claim 1, wherein the sub-pressurizing units are provided in pairs, each of which is disposed corresponding to an upper portion and a lower portion of a surface of the stack, and which simultaneously pressurize the upper portion and the lower portion of the surface of the stack.

15. an electrode unit manufacturing step of manufacturing electrode units in which electrodes and separators are alternately arranged; an electrode assembly manufacturing step of manufacturing an electrode assembly by disposing a separator sheet between the plurality of electrode units manufactured in the electrode unit manufacturing step; and an electrode assembly pressurizing step of pressurizing the electrode assembly, The electrode unit manufacturing step includes: a stacking step of alternately arranging the separators and the electrodes to form a stack; and a bonding step of bonding the separator and the electrode included in the laminate; The bonding step includes: an entire surface pressing step of pressing the entire surface of the laminate; and a first partial surface pressing step of pressing a partial surface of the laminate, the partial surface of which is where an edge portion of an electrode active material layer provided in the electrode is located, among the entire surface of the laminate; The edge portions are provided at both ends of the electrode active material layer provided on the electrode, a pair of drum units are provided to pressurize a portion of the surface of the laminate where the edge units provided at both ends of the electrode active material layer are located, The method for manufacturing a secondary battery, wherein the first partial surface pressing step is performed before the entire surface pressing step.

16. The electrode assembly pressurizing step includes: a second entire surface pressing step of pressing the entire surface of the electrode assembly; and 16. The method of claim 15, further comprising: a second partial surface pressing step of pressing a partial surface of the electrode assembly, the partial surface being where an edge portion of an electrode active material layer provided on the electrode is located, among the entire surface of the electrode assembly.

Images