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 including a pressurizing unit that pressurizes a stack in which electrodes and a separator are stacked, and a method for manufacturing a secondary battery using the same. The present invention provides a secondary battery manufacturing apparatus including a pressurizing unit that pressurizes a stack having electrodes and a separator, the pressurizing unit including a main pressurizing unit that pressurizes an entire surface of the stack; and a sub-pressurizing unit that pressurizes a portion of the stack; the portion of the stack is formed at an end of the stack in a longitudinal direction and includes a surface that is formed to have a relatively low height among the entire surface, and the sub-pressurizing unit presses the portion of the stack while moving in the longitudinal direction of the stack.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0152608 filed on November 8, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated as part of this specification.

[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 including a pressurizing unit that pressurizes a stack in which electrodes and a separator are stacked, and a method for manufacturing a secondary battery using the same. [Background technology]

[0003] Batteries generate electrical energy through physical or chemical reactions of substances and supply power to the outside world. They are used in living environments where we are surrounded by various electrical and electronic devices and are unable to obtain the AC power supplied to a building or when DC power is required.

[0004] Among these batteries, primary and secondary batteries, which are chemical batteries that utilize chemical reactions, are widely used, with primary batteries, commonly known as dry batteries, being expendable batteries, and secondary batteries, which are rechargeable batteries manufactured using materials that can repeat the oxidation-reduction process between electric current and substances multiple times, in which the power source is charged when a reduction reaction of the material occurs due to electric current, and the power source is discharged when an oxidation reaction of the material occurs, and 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, in which an active material, a conductive material, and a binder are mixed, 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 according to their structure. For example, the secondary batteries 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, and then storing the manufactured electrode assembly in a cylindrical can or the like and sealing the same, and pouch secondary batteries, which are manufactured by stacking electrode units of a predetermined size with a separator sheet interposed therebetween to manufacture an electrode assembly, and then storing the manufactured electrode assembly in a pouch and sealing the same.

[0007] Meanwhile, during the manufacture of an electrode, there is a problem in that the electrode slurry is applied non-uniformly to the conductive foil due to the viscosity of the electrode slurry, resulting in a difference in coating thickness of the electrode slurry. Such a difference in coating thickness of the electrode slurry results in an unbonded region of the electrode and the separator inside an electrode unit manufactured including the electrode. In addition, since a pouch-type secondary battery is manufactured by stacking an electrode unit on a separator sheet, an unbonded region is formed inside an electrode assembly including the electrode unit. Such an unbonded region causes lithium deposition due to the interface resistance of the negative electrode, which increases 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 having electrodes and a separator, the pressurizing unit including a main pressurizing unit that pressurizes an entire surface of the stack; and a sub-pressurizing unit that pressurizes a portion of the stack; the portion of the stack is formed at an end of the stack in a longitudinal direction and includes a surface that is formed to have a relatively low height among the entire surface, and the sub-pressurizing unit presses the portion of the stack while moving in the longitudinal direction of the stack.

[0010] In addition, the secondary battery manufacturing apparatus according to the present invention may further include a transfer unit configured to transfer the stack in one direction, and the sub-pressure unit may press the one surface while moving in a direction perpendicular to the one direction.

[0011] The sub-pressurizing unit may include: a drum unit that rotates to pressurize the partial surface of the laminate; and a rotating shaft that is coupled to the drum unit and rotates the drum unit.

[0012] The laminate may include an electrode tab connected to the electrode; and the partial surface may be located corresponding to a longitudinal end of the laminate where the electrode tab is located.

[0013] In addition, the secondary battery manufacturing apparatus according to the present invention may further include a heating unit that applies heat to the stack in which the electrodes and the separator are stacked.

[0014] The sub-pressurizing portion may be disposed in front of the main pressurizing portion.

[0015] The sub-pressurizing unit may pressurize the partial surface of the stack while moving from the inside to the outside of the stack.

[0016] The sub-pressure unit may be disposed behind the main pressure unit.

[0017] The sub-pressurizing section may pressurize the partial surface of the stack while moving from the outside to the inside of the stack.

[0018] The laminate is an electrode unit in which an electrode and a separator are laminated, and may be any one of a bi-cell, a mono-cell, and a full-cell.

[0019] The laminate may be an electrode assembly in which a plurality of electrode units, each of which has an electrode and a separator stacked thereon, and a separator sheet are stacked together.

[0020] Meanwhile, the present invention provides a method for manufacturing a secondary battery, comprising: a stack pressurizing step of pressurizing a stack having electrodes and a separator stacked thereon, the stack pressurizing step comprising: a full-surface pressurizing step of pressurizing an entire surface of the stack; and a partial-surface pressurizing step of pressurizing a portion of the stack; the partial surface is formed at an end of the stack in a longitudinal direction and comprises a surface having a relatively low height among the entire surface; and the partial-surface pressurizing step comprises pressing the partial surface while a sub-pressurizing unit that presses the partial surface moves in the longitudinal direction of the stack. Effect of the Invention

[0021] 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-pressurizing unit to pressurize a surface of the laminate that is formed with a relatively low height among the entire surface of the laminate.

[0022] In addition, the secondary battery manufacturing apparatus according to the present invention has the advantage that it can accommodate various sizes and shapes of surfaces of the stack that are formed with a relatively low height without replacing the sub-pressure unit by applying pressure in the longitudinal direction of the stack. [Brief description of the drawings]

[0023] [Figure 1a] FIG. 2 is a plan view showing the laminate as viewed from above. [Figure 1b] FIG. 1b is a side view showing the laminate of FIG. 1a as seen from the side. [Diagram 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 3a] 3 is a side view showing the side surface of the sub-pressure unit in FIG. 2 in more detail. [Figure 3b] FIG. 3B is an enlarged view of part A of FIG. 3A, showing in more detail how the sub-pressurizing unit presses the laminate; [Figure 4] 3 is a perspective view showing in more detail the state of a sub-pressure unit in the secondary battery production apparatus of FIG. 2. [Diagram 5] 4 is an image showing, in comparison, the formation of unbonded regions of bi-cells manufactured by a conventional secondary battery manufacturing apparatus and a secondary battery manufacturing apparatus according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention will be described in detail below with reference to the accompanying drawings, in order to enable a person skilled in the art to easily carry out the present invention. However, the present invention may be embodied in various different forms, and is not limited to the following embodiments.

[0025] 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.

[0026] Furthermore, the terms and words used in this specification and the claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner 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 manner.

[0027] The present invention provides an apparatus for manufacturing a secondary battery, including a pressurizing unit 100 for pressing a stack 10 in which electrodes and a separator are stacked.

[0028] First, the laminate 10 is a structure in which electrodes and a separator are laminated, and may have various configurations. Here, the laminate 10 may refer to an electrode unit, i.e., a unit cell, in which electrodes and a separator are laminated, 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 and separators are laminated, and a separator sheet are laminated.

[0029] Here, the electrode assembly may have any 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.

[0030] Here, the laminate 10 may be pressed by a pressurizing unit 100 to bond the electrodes and the separator, and the electrode unit and the separator sheet, to each other. In this case, the entire surface of the laminate 10 facing the pressurizing unit 100 and to be pressed is defined as an entire surface 11.

[0031] Meanwhile, as described above, the electrode slurry is unevenly applied on the electrode current collector (e.g., conductive foil) on the entire surface 11, resulting in a height difference. In particular, the surface of the entire surface 11 that is formed with a relatively low height is difficult to pressurize during the pressurization process, and remains as an unbonded region where the electrode-separator or electrode unit-separator sheet is not bonded, which causes lithium deposition on the interface of the negative electrode.

[0032] 1a to 1b, the entire surface 11 may include a part 12 including a surface formed with a relatively low height among the entire surface 11 of the laminate 10, and another part 13 formed with a constant height by uniformly applying an electrode slurry onto an electrode current collector. Meanwhile, the dotted line shown on the laminate 10 in the drawings is for dividing the part 12 and the other part 13, and does not mean that the internal structure of the laminate 10 is separated.

[0033] 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 collector, and may have various configurations.

[0034] As an example, the surface 12 may be a surface having a height difference, and may include a first surface 12a having a relatively lower height than the entire surface 11, and a second surface 12b having a higher height than the first surface 12a, as shown in FIG. 1b.

[0035] Here, the first partial surface 12a is a surface that is formed to have a relatively low height among the entire surface and corresponds to an unbonded area inside the laminate 10, and may be located at a first height H1 as shown in FIG. 1b.

[0036] The first height H1 is defined as a height from one surface of the laminate 10 located in the stacking direction of the electrodes and the separator to the other surface opposite the one surface, the height being relatively lower than a height H3 of the other surface 13 of the entire surface 11. Also, the height H3 of the other surface 13 is understood as a height from one surface of the laminate 10 located in the stacking direction of the electrodes and the separator in a region where the electrode slurry is uniformly applied on the electrode current collector to the other surface opposite the one surface.

[0037] In addition, the second surface 12b is a surface formed higher than the first surface 12a, and is formed in various directions from the first surface 12a 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.

[0038] For example, as shown in Fig. 1b, the second surface 12b may be formed between the first surface 12a and the other surface 13. However, the second surface 12b is not limited to this, and can be formed in various ways, such as being surrounded by the first surface 12a or being formed to surround the first surface 12a.

[0039] Further, the second surface 12b is a surface located at a second height H2, where the second height H2 is defined as a height from one surface of the laminate 10 located in the stacking direction of the electrodes and the separator to another surface opposite the one surface, the height being higher than the first height H1. Here, the second height H2 may be the same height as the height H3 of the other surface 13.

[0040] As another example, the partial surface 12 may be composed of only the first partial surface 12a formed to have a relatively low height among the entire surface 11.

[0041] Meanwhile, the partial surface 12 may be located at any part of the laminate 10 .

[0042] For example, as the length of the laminate 10 becomes longer, the electrode slurry tends to reach insufficiently the edge of the laminate 10, i.e., the end in the longitudinal direction of the laminate 10, when the electrode slurry is applied, and therefore the partial surface 12 is positioned to correspond to the end in the longitudinal direction of the laminate 10. Herein, the longitudinal direction of the laminate 10 is understood as a direction (y direction in FIG. 2) formed parallel to the long side of one surface of the laminate 10 located in the stacking direction of the electrodes and the separator.

[0043] In particular, the partial surface 12 is located in correspondence with the longitudinal end of the laminate 10 where the electrode tab 14 is located, among the longitudinal ends of the laminate 10. This is understood to be because, when manufacturing electrodes, when electrode slurry is applied to the center of one electrode current collector and dried, and then the center is cut to manufacture two electrodes, it is expected that the electrode slurry is sufficiently applied to the longitudinal end of the laminate 10, which was the center of the original electrode current collector, but the electrode slurry is likely to reach relatively insufficiently the longitudinal end of the electrode current collector where the electrode tab 14 is located.

[0044] 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.

[0045] The laminate 10 may be compressed by a compression unit 100 to bond the electrodes and the separator. Here, a plurality of laminates 10 may be transferred in one direction by a transfer unit 200 so as to be compressed more quickly. Here, the transfer unit 200 may be provided on one side facing the compression direction of the compression unit 100 and may include a conveyor belt, etc.

[0046] Meanwhile, the pressing unit 100 may be provided above the transfer unit 200 to pressurize the laminate 10 transferred from the transfer unit 200 .

[0047] Specifically, the pressure applying unit 100 according to the present invention may include a main pressure applying unit 110 for applying pressure to an entire surface 11 of the laminate 10, and a sub pressure applying unit 120 for applying pressure to a portion 12 of the laminate 10, as shown in FIG. 2.

[0048] Here, the main pressure section 110 is configured to apply pressure to the entire surface 11 of the laminate 10, and various configurations are possible.

[0049] For example, the main pressure unit 110 may be composed of 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 up and down. Here, when the laminate 10 is an electrode unit, the main pressure unit 110 may be composed of a roller, and when the laminate 10 is an electrode assembly, the main pressure unit 110 may be composed of a press.

[0050] Meanwhile, the sub-pressure unit 120 is configured to pressurize one surface 12 of the laminate 10, and may have various configurations.

[0051] Specifically, the sub-pressurizing unit 120 can improve unbonded areas of the laminate 10 by applying additional pressure in addition to the pressure applied by the main pressure unit 110 to a portion 12 of the entire surface 11, including a surface that is formed with a relatively low height.

[0052] Here, the sub-pressurizing unit 120 is provided movably, and thus can respond to various changes in the surface formed with a relatively low height among the entire surface 11 of each laminate 10. More specifically, the sub-pressurizing unit 120 may be provided movably, taking into consideration that the laminates 10 are formed with various lengths and widths for each model, and the regions where the electrode slurry does not reach are irregularly formed for each laminate 10.

[0053] In particular, the sub-pressurizing unit 120 may be provided to be movable in the longitudinal direction of the laminate 10, taking into consideration that the partial surface 12 is formed at the end of the longitudinal direction of the laminate 10 as described above.

[0054] Specifically, the sub-pressure unit 120 may apply pressure to the partial surface 12 while moving in the longitudinal direction of the laminate 10, as shown in FIG.

[0055] More specifically, as shown in FIG. 2, when the laminate 10 is transferred on the transfer section 200 in one direction (x direction in FIG. 2) perpendicular to the longitudinal direction of the laminate 10 (y direction in FIG. 2), the sub-pressure section 120 may be configured to pressurize the portion of the surface 12 while moving in a direction (y direction in FIG. 2) perpendicular to the transfer direction of the laminate 10 (x direction in FIG. 2).

[0056] In this case, the sub-pressurizing unit 120 can sequentially pressurize the laminate 10 in the longitudinal direction of the laminate 10 as shown in FIG. 3a, and therefore can pressurize the entire area of ​​the first surface 12a, regardless of the position of the first surface 12a, which is formed to have a relatively low height among the surfaces 12 formed at the longitudinal end of the laminate 10, as shown in FIG. 3b.

[0057] Here, when both the main pressure unit 110 and the sub pressure unit 120 are rollers, the rolling directions of the main pressure unit 110 and the sub pressure unit 120 may be perpendicular to each other.

[0058] It goes without saying that the sub-pressure section 120 may move in the longitudinal direction of the laminate 10 from the inside to the outside of the laminate 10, or from the outside to the inside of the laminate 10.

[0059] Meanwhile, the sub-pressurizing unit 120 may have various structures.

[0060] For example, as shown in FIG. 4, the sub-pressurizing unit 120 may include a drum unit 121 that rotates and pressurizes the portion 12 of the laminate 10; and a rotating shaft 122 that is connected to the drum unit 121 and rotates the drum unit.

[0061] Here, the drum unit 121 is configured to apply pressure to the surface 12 of the laminate 10 while rotating, and may have various configurations.

[0062] Specifically, the drum unit 121 rotates by a rotational force transmitted from a rotating shaft 122 and has various shapes. For example, the drum unit 121 has a cylindrical shape, a wheel shape having a plurality of spokes, etc.

[0063] Also, the drum unit 121 has various sizes. However, when the sub-pressure unit 120 moves in the longitudinal direction of the laminate 10, it is preferable that the width of the drum unit 121 is the same as or larger than the width of the laminate 10. Here, the width of the drum unit 121 and the width of the laminate 10 are understood as widths in the longitudinal direction of the laminate 10 transferred on the transfer unit 200.

[0064] Furthermore, the rotating shaft 122 is configured to be coupled with the drum portion 121 to rotate the drum portion, and may have various configurations.

[0065] For example, one end of the rotating shaft 122 may be connected to a driving motor to transmit a rotational force, and the rotational force of the driving motor 122 may be transmitted to the drum unit 121. Also, the rotating shaft 122 may include a bearing (not shown) provided between the rotating shaft 122 and the drum unit 121 to surround an outer circumferential surface of the rotating shaft 122.

[0066] Further, a support part 122' may be coupled to the rotating shaft 122, which is connected to a moving unit (not shown) that moves the sub-pressure part 120. Here, the support part 122' is coupled to rotatably support the rotating shaft 122, and may be coupled to the rotating shaft 122 via a bearing, for example.

[0067] Meanwhile, the moving unit (not shown) may have any configuration as long as it is configured to move the sub-pressurizer 120 in a horizontal direction and / or a vertical direction. For example, the moving unit (not shown) may include a coupling unit (not shown) coupled to the sub-pressurizer 120 in order to move the sub-pressurizer 120, and a driving unit (not shown) driving the coupling unit (not shown). Here, the coupling unit (not shown) may be coupled to the support 122' described above by a bolt coupling or the like, and the driving unit may include an actuator or the like.

[0068] Meanwhile, the sub-pressurizing unit 120 may be disposed at least one of the front and rear of the main pressurizing unit 110, and may pressurize a portion of the surface 12 of the laminate 10 before and / or after pressing the entire surface 11 of the laminate 10. Here, the direction facing the traveling direction of the laminate 10 on the conveying unit 200 is referred to as the front, and the opposite direction to the front is referred to as the rear.

[0069] As an example, the sub-pressurizing unit 120 may be disposed in front of the main pressurizing unit 110. In this case, since the laminate 10 is pressurized by the main pressurizing unit 110, when the sub-pressurizing unit 120 moves from the outside to the inside of the laminate 10, the electrodes and the separator are pushed, thereby generating air bubbles inside the laminate 10. Therefore, when the sub-pressurizing unit 120 is disposed in front of the main pressurizing unit 110, it is preferable that the sub-pressurizing unit 120 presses a portion of the surface 12 of the laminate 10 while moving from the inside to the outside of the laminate 10.

[0070] As another example, the sub-pressurizing unit 120 may be disposed behind the main pressurizing unit 110. In this case, since the laminate 10 is not pressurized, the sub-pressurizing unit 120 can pressurize a portion of the surface 12 of the laminate 10 while moving from the outside to the inside of the laminate 10. However, it goes without saying that even in this case, the sub-pressurizing unit 120 can pressurize a portion of the surface 12 of the laminate 10 while moving from the inside to the outside of the laminate 10.

[0071] Meanwhile, the secondary battery manufacturing apparatus according to the present invention may further include a heating unit 300 for applying heat to the laminate 10 .

[0072] The heating unit 300 is configured to apply heat to the laminate 10 in which the electrodes and the separator are laminated, and may have various configurations. Here, the heating unit 300 is disposed behind the pressurizing unit 100, and as described above, the rear may mean a direction opposite to the traveling direction of the laminate 10 on the conveyor belt.

[0073] More specifically, the heating unit 300 may be disposed behind the pressing unit 100 and may apply heat to the laminate 10 before the pressing unit 100 presses the laminate 10. That is, as the temperature of the laminate 10 increases, the adhesive strength between the electrodes and the separator is improved, and wrinkles formed in the electrodes, separator, separator sheet, etc. within the laminate during the manufacturing process may be improved.

[0074] At this time, the laminate 10 may be heated to a temperature above room temperature. Here, the room temperature refers to a temperature range called "room temperature" or normal temperature in the art. That is, it refers to the temperature in a laboratory, a research lab, etc., and is an expression of temperature conditions used when an experiment is performed without specifying or adjusting the temperature or when samples and materials are left indoors, and refers to the atmospheric temperature inside the room. Generally, it is a temperature at which humans can be comfortable, and is usually around 15°C to 20°C.

[0075] Meanwhile, the present invention provides a method for manufacturing a secondary battery, which includes a step of pressurizing a stack 10 in which electrodes and a separator are stacked.

[0076] Here, the laminate 10 is a structure in which electrodes and a separator are laminated, and may have various configurations. Here, the laminate 10 is an electrode unit, i.e., a unit cell, in which electrodes and a separator are laminated, 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 and separators are laminated, and a separator sheet are laminated.

[0077] The laminate pressing step may include a full surface pressing step of pressing the entire surface 11 of the laminate 10 ; and a partial surface pressing step of pressing a partial surface 12 of the laminate 10 .

[0078] First, the full surface pressing step is a step of pressing the entire surface 11 of the laminate 10, and can be performed by various methods.

[0079] Here, the entire surface 11 may be pressed by the main pressing unit 110 described above. However, since the electrode slurry is non-uniformly coated on the electrode current collector, which causes height differences across the entire surface of the laminate 10, an unbonded region may be generated on a portion 12 including a surface that is relatively low in height among the entire surface.

[0080] Meanwhile, the partial surface pressing step is a step of pressing a partial surface 12 of the laminate 10, and can be performed by various methods.

[0081] Specifically, the partial surface pressing step may be performed by pressing the partial surface 12 of the laminate 10 by the sub-pressurizing unit 120 in consideration of the transport speed and transport position of the laminate 10. Here, the detailed configuration and effects of the sub-pressurizing unit 120 are as described above.

[0082] In other words, the partial surface pressing step is a step of applying additional pressure to a portion 12 of the laminate 10 in order to improve the unbonded areas of the portion 12, and it goes without saying that the partial surface pressing step may be performed not only after the full surface pressing step is performed, but also before the full surface pressing step is performed.

[0083] More specifically, the partial surface pressing step may include a descending step of descending the sub-pressure unit 120 toward the laminate 10 at one position; a pressurizing and moving step of moving the laminate 10 while applying pressure in the longitudinal direction using the sub-pressure unit 120; and a returning step of returning the sub-pressure unit 120 to the one position.

[0084] Here, the lowering step is a step of lowering the sub-pressure unit 120 toward the laminate 10 at one position, and can be performed in various ways.

[0085] Specifically, the lowering step may be performed by using the above-mentioned moving unit (not shown) to lower the sub-pressure unit 120 so that it contacts and / or presses the laminate 10.

[0086] The pressure movement step is a step of moving the laminate 10 while applying pressure in the longitudinal direction by the sub-pressure unit 120, and can be performed by various methods.

[0087] Specifically, the pressure movement step may be performed by moving the sub-pressure section 120 horizontally in the longitudinal direction of the laminate 10 using the above-mentioned movement unit (not shown).

[0088] Furthermore, the returning step is a step of returning the sub-pressurizing unit 120 to the one position, and can be performed in various ways.

[0089] For example, the return step may be performed by using the aforementioned moving unit (not shown) to raise and horizontally move the sub-pressure unit 120 to return to the one position after the sub-pressure unit 120 finishes pressing the laminate 10.

[0090] The size of the unbonded area of ​​the laminate depending on whether the present invention is applied or not will be described below with reference to Fig. 5. Here, the laminate is a bi-cell, and Fig. 5(a) shows a front image of a bi-cell manufactured by the conventional technology (hereinafter referred to as "Comparative Example"), and Fig. 5(b) shows a front image of a bi-cell manufactured by the present invention (hereinafter referred to as "Example of the present invention").

[0091] First, in the front image of the bi-cell formed according to the comparative example in FIG. 5(a), it can be seen that a black electrode-separator unbonded area is formed on the top of the bi-cell, i.e., on edge B corresponding to the electrode tab. In addition, in the case of an electrode assembly including the above-mentioned unit cells, it is expected that an unbonded area will occur between the unit cell and the separator sheet, and lithium will be deposited on the negative electrode, increasing the resistance of the electrode. This will result in a problem of reduced performance of the secondary battery.

[0092] In contrast, looking at the front image of the bi-cell formed according to an embodiment of the present invention in Fig. 5(b), it can be seen that there is almost no unbonded area formed at the top of the bi-cell, i.e., at edge B corresponding to the electrode tab. Therefore, it is expected that the electrode unit formed according to the embodiment of the present invention will not only have an unbonded area between the electrode and separator inside the electrode unit, but also an unbonded area between the unit cell and separator sheet on the electrode assembly, which is advantageous in that it can minimize lithium deposition due to interfacial resistance on the negative electrode and improve the performance of the secondary battery.

[0093] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and various implementations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the appended claims. [Explanation of symbols]

[0094] 10 Laminate 11 Full surface 12 Partial side 12a Page 1 12b Part 2 13 Other parts 14 Electrode tab 100 Pressurizing section 110 Main pressure section 120 Sub-pressure section 121 Drum Section 122 Rotational Axis 122' Support 200 Transfer section 300 Heating section H1 1st height H2 2nd height H3 3rd Height

Claims

1. In a secondary battery manufacturing apparatus including a pressurizing unit that pressurizes a stack of electrodes and a separator, The pressure applying unit is A main pressing section that presses the entire surface of the laminate; and a sub-pressure unit that presses a part of the laminate; The part of the surface is a surface formed at an end of the laminate in a longitudinal direction and having a relatively low height among the entire surface; The sub-pressurizing unit includes: A secondary battery manufacturing apparatus that applies pressure to the partial surface while moving the laminate in the longitudinal direction.

2. The laminate further includes a conveying unit that conveys the laminate in one direction, The sub-pressurizing unit includes: The secondary battery manufacturing apparatus according to claim 1 , wherein the one surface is pressed while moving in a direction perpendicular to the one direction.

3. The sub-pressurizing unit includes: A drum unit that rotates and presses the partial surface of the laminate; and The secondary battery manufacturing apparatus according to claim 1 , further comprising: a rotating shaft coupled to the drum portion for rotating the drum portion.

4. the laminate includes an electrode tab connected to the electrode; The apparatus of claim 1 , wherein the surface is located in correspondence with an end portion of the laminate in a longitudinal direction where the electrode tab is located.

5. The apparatus for manufacturing a secondary battery according to claim 1 , further comprising a heating unit for applying heat to the stack in which the electrodes and the separator are stacked.

6. The secondary battery manufacturing apparatus according to claim 1 , wherein the sub-pressurizing unit is disposed in front of the main pressurizing unit.

7. The sub-pressurizing unit includes: The secondary battery manufacturing apparatus according to claim 6 , wherein the pressure is applied to the surface of the stack while moving from the inside to the outside of the stack.

8. The secondary battery manufacturing apparatus according to claim 1 , wherein the sub-pressurizing unit is disposed behind the main pressurizing unit.

9. The sub-pressurizing unit includes: The secondary battery manufacturing apparatus according to claim 8 , wherein the pressure is applied to the surface of the stack while moving from the outside to the inside of the stack.

10. 2. The apparatus of claim 1, wherein the stack is an electrode unit in which an electrode and a separator are stacked, and is one of a bi-cell, a mono-cell, and a full-cell.

11. 2. The apparatus of claim 1, wherein the stack is an electrode assembly in which a separator sheet and a plurality of electrode units each having an electrode and a separator stacked thereon are stacked.

12. 1. A method for manufacturing a secondary battery, comprising: pressing a stack having an electrode and a separator laminated thereon, The laminate pressing step includes: A full surface pressing step of pressing the entire surface of the laminate; and A partial surface pressing step of pressing a partial surface of the laminate; The part of the surface is a surface formed at an end of the laminate in a longitudinal direction and having a relatively low height among the entire surface; The partial surface pressing step includes: The method for manufacturing a secondary battery, wherein a sub-pressure unit that presses the portion of the surface presses the portion of the surface while moving in a longitudinal direction of the stack.

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