Method and apparatus for manufacturing unit cells

Abstract

The present invention relates to an apparatus for manufacturing unit cells, which apparatus cuts a lower separator and an upper separator between electrodes adjacent to each other in a process of manufacturing unit cells performed in a state in which the lower and upper separators are continuously moved in a length direction and electrodes are stacked between the lower and upper separators and on the upper separator, respectively, the apparatus including: a lower roller provided below the lower separator; and an upper roller provided above the upper separator in alignment with the lower roller and having an elliptical shape including a major axis and a minor axis, wherein the upper roller does not contact the upper separator as the electrodes pass during rotation of the upper roller, and after the electrodes pass, the upper roller presses the upper and lower separators toward a surface of the lower roller, and at least one of the lower and upper rollers is heated to a predetermined temperature to thermally fuse portions of the upper and lower separators pressed.

Description

Technical Field

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0182655, filed on December 23, 2020, and Korean Patent Application No. 10-2021-0184173, filed on December 21, 2021, the entirety of which is incorporated herein by reference.

[0002] The present invention relates to a method and apparatus for manufacturing a cell, and more specifically, to a method and apparatus for manufacturing a cell in which portions of the lower and upper separators to be cut are pre-bonded (sealed) before cutting the lower and upper separators to prevent separator folding. Background Technology

[0003] Unlike primary batteries, secondary batteries have been the subject of extensive research and development in recent years due to their rechargeability, miniaturization, and large capacity. Furthermore, with technological advancements and increasing demand for mobile devices, the need for secondary batteries as an energy source is rapidly growing.

[0004] This secondary battery is configured to house the electrode assembly and electrolyte within a casing (e.g., a bag, can, etc.). The electrode assembly, mounted within the casing, is repeatedly charged and discharged due to its positive / separator / negative electrode stacked structure. The electrode assembly is manufactured in various ways. However, typically, the electrode assembly can be manufactured in a manner in which multiple cell 4 are stacked after pre-fabrication of the cell 4.

[0005] That is to say, refer to Figure 1 The diagram illustrates the state of manufacturing a cell according to the related technology. In the method of manufacturing cell 4 according to the related technology, the positive electrode 1, the upper separator 3a, the negative electrode 2 and the lower separator 3b are continuously unfolded and supplied while the positive electrode 1, the upper separator 3a, the negative electrode 2 and the lower separator 3b are each wound into a roll (however, the stacking positions of the positive electrode and the negative electrode may be different).

[0006] The diaphragms 3 (3a and 3b) are continuously supplied without interruption, with the negative electrode 2 supplied between the upper diaphragm 3a and the lower diaphragm 3b, and the positive electrode 1 supplied on the upper diaphragm 3a.

[0007] Here, the diaphragm 3 is continuously supplied without being cut. On the other hand, the positive electrode 1 and the negative electrode 2 are provided in a state where they are cut into predetermined sizes by the cutters 6 and 7, respectively. The positive electrode 1 and the negative electrode 2 are stacked in pairs, aligned vertically with each other across the upper diaphragm 3a, and are set to be separated from the adjacent positive electrode 1 and negative electrode 2 by a predetermined distance.

[0008] That is, the diaphragms 3 are continuously connected, and the negative electrode 2 and the positive electrode 1 pass through the laminating device 9 while being separated by a predetermined distance from the adjacent negative electrode 2 and positive electrode 1. In the laminating device 9, heat and pressure are applied to bond the negative electrode 2 and the positive electrode 1 to the portion in contact with the diaphragm 3.

[0009] After the positive electrode 1 and negative electrode 2 are bonded to the diaphragm 3 and pass through the lamination device 9, the positive electrode 1 and negative electrode 2 are further pressed by the pressing device 5, which consists of cylindrical rollers arranged in pairs.

[0010] Then, the separator 3 is cut by the cutter 8 between adjacent positive electrodes 1 and then supplied to individual cell 4.

[0011] That is, after the electrodes 1 and 2 are bonded to the separator 3 by applying heat and pressure through the laminating device 9 and the pressing device 5, the separator 3 is cut between adjacent electrodes so that the separator 3 is manufactured into individual cell 4.

[0012] However, the cutter 8 has a structure that applies pressure from above and below to cut the diaphragm 3. Therefore, if either diaphragm 3a or 3b is not properly cut, there is a problem that diaphragms 3a and 3b fold in the direction of applied pressure.

[0013] Furthermore, after manufacturing the cell 4, since multiple cell 4 are stacked to manufacture the electrode assembly, a short circuit occurs within the electrode assembly when the separator 3 folds and thus a portion of the negative electrode 2 or positive electrode 1 is exposed.

[0014] That is, the diaphragm 3 is bonded to the parts where it contacts the electrodes 1 and 2. However, in the structure according to the related technology, the upper diaphragm 3a and the lower diaphragm 3b are not bonded to each other, so when cutting is performed by the cutter 8, or after cutting, there is a problem that the diaphragm cannot be fixed and instead folds. Summary of the Invention

[0015] Technical issues

[0016] Therefore, the object of the present invention is to provide a method and apparatus for manufacturing a cell, wherein the upper and lower separators are bonded (sealed) before the separator is cut (before the portion of the separator to be cut reaches the cutter 8), thereby preventing the upper and lower separators from folding when the separator is cut.

[0017] Technical solution

[0018] To achieve the above objective, in a process of manufacturing a cell according to the present invention, in which a lower separator and an upper separator are continuously moved along their length and electrodes are stacked between and on the upper separator (i.e., stacked in the order of "positive electrode / upper separator / negative electrode / lower separator" or "negative electrode / upper separator / positive electrode / lower separator"), the lower separator and the upper separator are cut between adjacent electrodes (positive and negative electrodes) (along the length direction of the separator). The device includes: a lower roller disposed below the lower diaphragm; and an upper roller, the upper roller being vertically aligned with the lower roller above the upper diaphragm and having an elliptical shape including a major axis and a minor axis, wherein, when the electrode passes by during rotation of the upper roller, the upper roller does not contact the upper diaphragm, and after the electrode passes, the upper roller presses the upper diaphragm and the lower diaphragm against the surface of the lower roller, and at least one of the lower roller and the upper roller is heated to a predetermined temperature to thermally fuse the pressed portions of the upper diaphragm and the lower diaphragm.

[0019] The upper roller and the lower roller may be configured to thermally fuse the upper diaphragm and the lower diaphragm before the upper diaphragm and the lower diaphragm are cut.

[0020] The portion of the upper roller that contacts the upper diaphragm may be made of an elastic material.

[0021] The upper roller may include: a core made of a material with relatively higher hardness; and a surface portion combined with the core to cover the surface of the core, the surface portion being made of a material with relatively higher elasticity and in contact with the upper diaphragm.

[0022] The surface portion may be made of a material having a Shore hardness in the range of HS20 to HS40.

[0023] At least one of the lower roller and the upper roller can be heated to a range of 60°C to 110°C.

[0024] When the lower roller and the upper roller press the lower diaphragm and the upper diaphragm, the pressure applied between the lower roller and the upper roller can be set in the range of 100 kg to 1000 kg.

[0025] The lower roller may be heated and the upper roller may not be heated. Alternatively, the lower roller may not be heated and the upper roller may be heated. Alternatively, both the lower and upper rollers may be heated.

[0026] Furthermore, the present invention provides a method for manufacturing a cell in which electrodes are respectively stacked between a lower separator and an upper separator and on the upper separator. The method includes the following steps: providing the electrodes, the upper separator, and the lower separator while the lower separator and the upper separator are continuously moved along their length and the electrodes are respectively stacked between the lower separator and the upper separator and on the upper separator; and passing the electrodes, the upper separator, and the lower separator between a lower roller disposed below the lower separator and an upper roller disposed above the upper separator and having an elliptical shape including a minor axis and a major axis, wherein, when the electrodes pass by during the rotation of the upper roller, the upper roller does not contact the upper separator, and after the electrodes pass by, the upper roller presses the upper separator and the lower separator against the surface of the lower roller, and at least one of the lower roller and the upper roller is heated to a predetermined temperature to thermally fuse the pressed portions of the upper separator and the lower separator.

[0027] The upper roller and the lower roller may be configured to thermally fuse the upper diaphragm and the lower diaphragm before the upper diaphragm and the lower diaphragm are cut.

[0028] The upper roller may be made of an elastic material, such that when the upper diaphragm is pressed, the upper diaphragm is pressed by the elasticity of the material of the upper roller.

[0029] Beneficial effects

[0030] The present invention, configured as described above, may include an upper roller having an elliptical shape and a lower roller having a circular shape. Here, at least one of the upper and lower rollers may be heated to a predetermined temperature, and the long axis of the upper roller may press against the diaphragm to bond (thermally fuse) the upper diaphragm to the lower diaphragm. Thus, folding of the diaphragm can be prevented after cutting.

[0031] The part of the upper roller that comes into contact with the diaphragm can be made of an elastic material to prevent the diaphragm from being damaged when pressed. Attached Figure Description

[0032] Figure 1 It is a schematic diagram illustrating the state of a cell manufactured according to a method based on relevant technologies.

[0033] Figure 2 The image shows a simplified front view (left) of an apparatus for manufacturing a cell according to an embodiment of the present invention, and a cross-sectional view (right) of each of the upper and lower rollers.

[0034] Figure 3 This diagram illustrates the state when the major axis of the upper roller is perpendicular to the lower roller. And the state when the minor axis of the upper roller is perpendicular to the lower roller. The illustration.

[0035] Figure 4 This diagram illustrates the state where the minor axis of the upper roller is perpendicular to the lower roller when the electrode is positioned between the upper and lower rollers.

[0036] Figure 5 This is a diagram illustrating the state where the diaphragm is positioned between the upper and lower rollers, with the long axis of the upper roller perpendicular to the lower roller and pressing against the diaphragm.

[0037] Figure 6 The diagram illustrates the states of the upper roller being heated and the lower roller not being heated (i), the upper roller not being heated and the lower roller being heated (ii), and the state of both the upper and lower rollers being heated (iii). Detailed Implementation

[0038] Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings, in a manner that allows those skilled in the art to readily implement the invention. However, the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein.

[0039] For clarity of description, irrelevant parts have been omitted, and the same reference numerals are assigned to the same or similar parts throughout the application.

[0040] Furthermore, the terms or words used in this specification and claims should not be construed as having a general meaning or a dictionary-based meaning, but should be interpreted as meanings and concepts that are within the scope of the invention, based on the principle that the inventor is able to properly define the concepts of the terms in order to best describe and interpret his or her invention.

[0041] This invention relates to a method and apparatus for manufacturing a unit cell 4 in which electrodes 1 and 2 are respectively stacked between and on the lower separator 3b and the upper separator 3a. Embodiments according to the invention will be described in more detail below with reference to the accompanying drawings.

[0042] First Implementation Method

[0043] According to a first embodiment, the present invention provides an apparatus for manufacturing cell batteries. The apparatus for manufacturing cell batteries provided in this embodiment can be added to... Figure 1 The pressing device 5 in the process shown can be installed between the cutting device 8 or can replace the pressing device 5.

[0044] Figure 2 This is a simplified front view (left) of an apparatus for manufacturing a cell according to an embodiment of the present invention, and a cross-sectional view (right) of each of the upper and lower rollers. Figure 3 This diagram illustrates the state when the major axis of the upper roller is perpendicular to the lower roller. And the state when the minor axis of the upper roller is perpendicular to the lower roller. The illustration.

[0045] As shown in the figure, the apparatus for manufacturing cell units according to the present invention includes a lower roller 10 and an upper roller 20. The upper roller 20 and the lower roller 10 are configured to thermally fuse the upper separator 3a to the lower separator 3b before the upper separator 3a and the lower separator 3b are cut.

[0046] Since the device for manufacturing the cell provided in this embodiment is provided in place of the pressing device 5 according to the related technology or is additionally provided between the pressing device 5 and the cutter 8, in the separator 3 and the electrodes 1 and 2, the lower separator 3b and the upper separator 3a move continuously along the length direction and are set in a state in which the positive electrode 1 and the negative electrode 2 are stacked between the lower separator 3b and the upper separator 3a and on the upper separator 3a, respectively, that is, in a state in which "positive electrode / upper separator / negative electrode / lower separator" or "negative electrode / upper separator / positive electrode / lower separator" are stacked sequentially from top to bottom.

[0047] The lower roller 10 has a circular shape and is disposed below the lower diaphragm 3b. Furthermore, the lower roller 10 is configured to be heated to a predetermined temperature by a heater (not shown) or the like.

[0048] In this embodiment, the lower roller 10 can be heated to a range of 60°C to 110°C. The reason for limiting the temperature to a range of 60°C to 110°C is that when the temperature is below 60°C, it is difficult to achieve effective thermal fusion of the diaphragm 3, and when the temperature exceeds 110°C, it is difficult to seal the diaphragm 3 due to melting (deformation or damage).

[0049] Furthermore, the upper roller 20 is vertically aligned with the lower roller 10 above the upper diaphragm 3a and is configured to have an elliptical shape including a minor axis and a major axis. The upper roller 20 can also be heated to a range of 60°C to 110°C by an external heater (not shown).

[0050] Therefore, such as Figure 3 As shown, when the major axis is vertical, the gap between the upper roller 20 and the lower roller 10 is relatively small, and when the minor axis is vertical, the gap between the upper roller 20 and the lower roller 10 is relatively large. That is to say, the gap between the upper roller 20 and the lower roller 10 varies depending on the rotational position of the upper roller 20.

[0051] like Figure 2 As shown, the upper roller 20 and the lower roller 10 rotate axially via motors M1 and M2, respectively, and the upper roller 20 and the lower roller 10 rotate along the width direction ( Figure 2 The left and right directions are kept at a constant interval. The rotation speed of each of the motors M1 and M2 can be adjusted according to the conveying speed of each of the diaphragms 3a and 3b. The lower roller 10 and the upper roller 20 can be rotated simultaneously using a single motor.

[0052] When the upper roller 20 comes into contact with the upper diaphragm 3a, the part of the upper roller 20 that comes into contact with the upper diaphragm 3a is made of an elastic material to prevent the diaphragms 3a and 3b from being damaged.

[0053] That is, the upper roller 20 may include: a core 21 made of a material with relatively higher hardness; and a surface portion 22 combined with the core 21 to cover the surface of the core 21, the surface portion 22 being made of a material with relatively higher elasticity and in contact with the upper diaphragm 3a.

[0054] The surface portion 22 may be made of a rubber or silicone material with appropriate elasticity and may have a Shore hardness in the range of HS20 to HS40. In addition, the core portion 21 is made of a metal material with higher hardness, thereby supporting the surface portion when it undergoes elastic deformation.

[0055] Figure 4 This diagram illustrates the state where the minor axis of the upper roller 20 is perpendicular to the lower roller 10 when the electrode is positioned between the upper roller 20 and the lower roller 10. Figure 5 This diagram illustrates the state where, with only diaphragms 3a and 3b positioned between the upper roller 20 and the lower roller 10, the long axis of the upper roller 20 is perpendicular to the lower roller 10, pressing down on the diaphragms 3a and 3b. Furthermore, Figure 6 The diagram illustrates the states of the upper roller being heated and the lower roller not being heated (i), the upper roller not being heated and the lower roller being heated (ii), and the state of both the upper and lower rollers being heated (iii).

[0056] Reference Figure 4 and Figure 5 In this embodiment, the upper roller 20 and lower roller 10 of the device for manufacturing cell batteries are installed before the separator 3 reaches the cutter 8. When the electrodes 1 and 2 pass by during the rotation of the upper roller 20, the upper roller 20 does not contact the upper separator 3a, and after the electrodes 1 and 2 pass by, the upper roller 20 presses the upper separator 3a and the lower separator 3b onto the surface of the lower roller 10.

[0057] That is, when electrodes 1 and 2 pass below the upper roller 20, the upper roller 20 has an orientation with its minor axis in the vertical direction (the direction in which the minor axis is placed vertically). Therefore, the upper roller 20 does not contact the uppermost positive electrode 1. Furthermore, when the diaphragm 3 (in...) Figure 4 When the upper roller 20 moves to the right, it also rotates counterclockwise. Therefore, when the long axis of the upper roller 20 rotates to a vertical position (along the direction in which the long axis is vertically set), the diaphragm 3a begins to be pressed and comes into contact with the lower diaphragm 3b.

[0058] Here, at least one of the lower roller 10 rotating below the lower diaphragm 3b and the upper roller 20 rotating above the upper diaphragm 3a is heated to a predetermined temperature. Furthermore, since the upper diaphragm 3a and the lower diaphragm 3b are pressed against the surface of the lower roller 10, the lower diaphragm 3b is heat-fused and sealed to the upper diaphragm 3a.

[0059] Furthermore, when the thermal fusion of diaphragms 3a and 3b is achieved, the upper roller 20 moves along the axis based on... Figure 5 Rotate counterclockwise, as Figure 4 As shown in the diagram, the upper diaphragm 3a and the lower diaphragm 3b are thermally fused together again in the same manner as the subsequent electrodes 1 and 2 pass by.

[0060] The part that is thermally fused in this way is Figure 1 The cutter 8 shown cuts to manufacture the cell battery 4.

[0061] The pressure applied to the diaphragm 3 can vary depending on the material of the upper roller 20 and the spacing between the upper roller and the lower roller 10. Here, when the thickness of the diaphragm made of polyethylene (PE) material is 8 μm to 20 μm, it is preferable that the pressure applied to each of the lower and upper diaphragms by the lower roller 10 and the upper roller 20 is set at a pressure per unit area (1 cm²). 2 or 1m 2 The range is from 100kg to 1000kg.

[0062] Furthermore, the lower roller 10 has a cylindrical shape. As long as the lower roller 10 is configured to effectively transfer the heat of the heater 11 included therein to the surface of the housing 12, the lower roller 10 is not limited to a specific structure, but it is preferred to have a straightness of 5 / 1000 or less, a surface roughness Ra of 0.8 or less, and a centrifugal separation rate of 8 / 1000 or less, so as to uniformly maintain the sealing quality of the sealed portion.

[0063] In the apparatus for manufacturing cell cells according to the present invention, the upper roller 20 and the lower roller 10 may be configured to be heated, taking into account the material or thickness of each separator 3a and 3b, the spacing between electrodes, the heating temperature, etc.

[0064] That is to say, such as Figure 6 As shown in the diagram, i.e., as shown in the left figure (i), only the upper roller 20 can be heated when the lower roller 10 is not heated. In this case, since heat is not unnecessarily transferred to electrodes 1 and 2 (through the heated lower roller), thermal damage to electrodes 1 and 2 can be prevented.

[0065] Furthermore, as shown in the intermediate figure (ii), the upper roller 20 may not be heated while the lower roller 10 is heated. In this case, since the lower diaphragm 3b is heated along its length, the heat fusion quality can be adjusted by regulating the pressing pressure via the upper roller 20. In particular, the rollers can be configured in this way when heat is difficult to transfer via the upper roller 20 depending on the material of the surface portion.

[0066] Furthermore, as shown in Figure (iii) on the right, both the lower roller 10 and the upper roller 20 can be heated. In this case, heat can be uniformly transferred to the upper diaphragm 3a and the lower diaphragm 3b, thereby improving the thermal fusion efficiency.

[0067] Therefore, the apparatus for manufacturing cell batteries provided in this embodiment can be configured such that at least one or all of the upper roller 20 and the lower roller 10 are heated, depending on the required heat fusion specifications, the construction of the upper roller 20 and the lower roller 10, the thickness or type of each separator 3a and 3b, etc.

[0068] Second Implementation Method

[0069] In this invention, as a second embodiment, a method for manufacturing a unit cell using the above-described manufacturing equipment is provided.

[0070] The manufacturing method provided in this embodiment includes the following steps: after stacking electrodes 1, 2 and diaphragm 3 in a predetermined order, laminating electrodes 1, 2 and diaphragm 3 to provide electrodes 1, 2 and diaphragm 3; and passing diaphragm 3 between upper roller 20 and lower roller 10.

[0071] That is, in the process of providing electrodes 1, 2 and diaphragm 3, the lower diaphragm 3b and the upper diaphragm 3a move continuously along the length direction. In addition, electrodes 1, 2 and diaphragm 3 are configured such that electrodes 1 and 2 are stacked between the lower diaphragm 3b and the upper diaphragm 3a and on the upper diaphragm 3a, respectively.

[0072] Furthermore, in the process of passing the diaphragm 3 between the upper roller 20 and the lower roller 10, the electrodes 1, 2 and the diaphragm 3 are configured to pass between the lower roller 10, which is disposed below the lower diaphragm 3b, and the upper roller 20, which is disposed above the upper diaphragm 3a and is aligned vertically with the lower roller 10, and has an elliptical shape including a short axis and a long axis.

[0073] Here, as electrodes 1 and 2 pass by during the rotation of the upper roller 20, the upper roller 20 does not contact the upper diaphragm 3a and the positive electrode 1 stacked on the top layer. After electrodes 1 and 2 pass by, the upper roller 20 presses the upper diaphragm 3a and the lower diaphragm 3b onto the surface of the lower roller 10 for thermal fusion. Here, the upper roller 20 is made of an elastic material, such that when the upper diaphragm 3a is pressed, the upper diaphragm 3a is pressed by the elasticity of the material of the upper roller 20. Here, at least one of the upper roller 20 and the lower roller 10 is heated to perform thermal fusion at the pressed portions of the diaphragms 3a and 3b.

[0074] The portion that is thermally fused by the upper roller 20 and the lower roller 10 is moved to a subsequent position to be cut by the cutter 8.

[0075] The present invention, configured as described above, includes an upper roller 20 having an elliptical shape and a lower roller 10 having a circular shape. At least one of the upper roller 20 and the lower roller 10 is heated to a predetermined temperature, such that the long axis of the upper roller 20 presses against diaphragms 3a and 3b to bond (thermally fuse) the upper diaphragm 3a to the lower diaphragm 3b. Therefore, due to the sealing of the cut portion, the diaphragms 3a and 3b are fixed after cutting, thereby preventing folding.

[0076] The portion of the upper roller 20 that comes into contact with the diaphragm 3 may be made of an elastic material to prevent the diaphragm 3 from being damaged when pressed.

[0077] Although embodiments of the invention have been described with reference to specific examples, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

[0078] [Description of reference markers]

[0079] 1: Positive electrode

[0080] 2: Negative electrode

[0081] 3: Diaphragm (3a: upper diaphragm, 3b: lower diaphragm)

[0082] 10: Lower roller

[0083] 11: Heater

[0084] 12: Outer shell

[0085] 20: Upper roller

[0086] 21: Core part

[0087] 22: Surface part.

Claims

1. An apparatus for manufacturing a cell, the apparatus continuously moving a lower separator and an upper separator along a length direction, stacking electrodes between the lower separator and the upper separator and on the upper separator, respectively, and cutting the lower separator and the upper separator between adjacent electrodes to manufacture a cell wherein the electrodes are stacked between the lower separator and the upper separator and on the upper separator, the apparatus comprising: The lower roller is disposed below the lower diaphragm; and The upper roller, which is vertically aligned with the lower roller and positioned above the upper diaphragm, has an elliptical shape including a major axis and a minor axis. During the rotation of the upper roller, as the electrode passes by, the short axis of the upper roller is perpendicular to the lower roller, thus separating the upper roller from the upper diaphragm without contacting it. After the electrode passes, the long axis of the upper roller is perpendicular to the lower roller, thus pressing the upper and lower diaphragms against the surface of the lower roller. At least one of the lower roller and the upper roller is heated to a predetermined temperature to thermally fuse the pressed portions of the upper and lower diaphragms along the width direction perpendicular to the length direction before the upper and lower diaphragms are cut.

2. The apparatus of claim 1, wherein the portion of the upper roller in contact with the upper diaphragm is made of an elastic material.

3. The apparatus according to claim 2, wherein the upper roller comprises: A core made of a material with relatively higher hardness; and A surface portion that is combined with the core to cover the surface of the core, the surface portion being made of a material with relatively higher elasticity and in contact with the upper diaphragm.

4. The device according to claim 3, wherein the surface portion is made of a material having a Shore hardness in the range of HS20 to HS40.

5. The apparatus of claim 1, wherein at least one of the lower roller and the upper roller is heated to a range of 60°C to 110°C.

6. The device according to claim 3, wherein, When the lower roller and the upper roller press the lower diaphragm and the upper diaphragm, the pressure applied between the lower roller and the upper roller is set in the range of 100 kg to 1000 kg.

7. The apparatus of claim 1, wherein the lower roller is heated and the upper roller is not heated.

8. The apparatus of claim 1, wherein the lower roller is not heated and the upper roller is heated.

9. The apparatus according to claim 1, wherein both the lower roller and the upper roller are heated.

10. A method for manufacturing a cell in which electrodes are respectively stacked between a lower separator and an upper separator and on the upper separator, the method comprising the following steps: The electrodes, the upper septum, and the lower septum are provided in a state where the lower septum and the upper septum are continuously moved along the length direction and the electrodes are respectively stacked between the lower septum and the upper septum and on the upper septum; and The electrode, the upper diaphragm, and the lower diaphragm are passed between a lower roller disposed below the lower diaphragm and an upper roller disposed above the upper diaphragm and having an elliptical shape including a minor axis and a major axis. in, As the electrode passes during the rotation of the upper roller, the short axis of the upper roller is perpendicular to the lower roller, thus separating the upper roller from the upper diaphragm without contacting it. After the electrode passes, the long axis of the upper roller is perpendicular to the lower roller, thus pressing the upper and lower diaphragms against the surface of the lower roller. At least one of the lower roller and the upper roller is heated to a predetermined temperature to thermally fuse the pressed portions of the upper and lower diaphragms along the width direction perpendicular to the length direction before the upper and lower diaphragms are cut.

11. The method of claim 10, wherein the upper roller is made of an elastic material such that when the upper diaphragm is pressed, the upper diaphragm is pressed by the elasticity of the material of the upper roller.

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