Method for manufacturing a secondary battery and apparatus for manufacturing a secondary battery

Abstract

The present invention relates to a method for manufacturing a secondary battery and an apparatus for manufacturing a secondary battery. The method for manufacturing a secondary battery according to the present invention includes: an accommodation step of accommodating an electrode assembly in which electrodes and separators are alternately stacked, an electrolyte, and one side portion of an electrode lead connected to the electrode in a bag to form a battery cell; an activation step of charging the battery cell to activate the battery cell; a pressing step of sequentially pressing the battery cell by a pressing roller after the activation step to roll the battery cell; and a degassing step of discharging internal gas of the battery cell to the outside after the pressing step.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2020-0083106, filed on July 6, 2020, and Korean Patent Application No. 10-2021-0087119, filed on July 2, 2021, the entire disclosures of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a method of manufacturing a secondary battery and an apparatus for manufacturing a secondary battery. Background Art

[0004] Unlike primary batteries, secondary batteries are rechargeable and have a higher potential for compact size and high capacity. Thus, many studies have recently been conducted on secondary batteries. With the development of technology and the increasing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing.

[0005] According to the shape of the battery case, rechargeable batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries. A secondary battery houses an electrode assembly and an electrolyte. In such a secondary battery, the electrode assembly installed in the battery case is a power generation device capable of charging and discharging having a structure in which electrodes and a separator are stacked.

[0006] Electrode assemblies can be roughly classified into jelly-roll type electrode assemblies, stacked type electrode assemblies, and stacked / folded type electrode assemblies. In a jelly-roll type electrode assembly, a separator is interposed between a positive electrode and a negative electrode, and each of the positive electrode and the negative electrode is provided in the form of a sheet coated with an active material, and then the positive electrode, the separator, and the negative electrode are wound. In a stacked type electrode assembly, a plurality of positive electrodes and negative electrodes are sequentially stacked with a separator therebetween. In a stacked / folded type electrode assembly, a stacked unit cell is wound together with an isolation film having a longer length.

[0007] In an activation process during the manufacturing process of a secondary battery, a solid electrolyte interface (SEI layer) is generated through an electrochemical reaction between an electrode active material and an electrolyte, and as a result, activation gas is generated as a by-product.

[0008] The generated activation gas is removed through a degas process, however, when the gas remains in the battery cell due to a degas defect, a gas trap is generated. Thus, the gas trap causes a problem of lithium precipitation during a subsequent charge / discharge process.

[0009] [Prior Art Documents] (Patent Document) Korean Patent Publication No. 10-2014-0015647 Summary of the Invention

[0010] Technical Problem

[0011] One aspect of the present invention is to provide a method and apparatus for manufacturing a secondary battery capable of effectively removing internal gas.

[0012] Technical Solution

[0013] A method for manufacturing a secondary battery according to an embodiment of the present invention includes: an accommodation process of accommodating, in a bag, an electrode assembly in which electrodes and separators are alternately stacked, an electrolyte, and one side portion of an electrode lead connected to the electrodes to form a battery cell; an activation process of charging the battery cell to activate the battery cell; a pressing process of sequentially pressing the battery cell with a pressing roller after the activation process to roll the battery cell; and a degassing process of discharging the internal gas of the battery cell to the outside after the pressing process, wherein, in the pressing process, the main body of the bag accommodating the electrode assembly is pressed such that a portion of the main body other than the edge is pressed.

[0014] An apparatus for manufacturing a secondary battery according to an embodiment of the present invention includes: a pressing roller configured to sequentially roll a battery cell in which an electrode assembly and an electrolyte are accommodated in a bag after an activation process and before a degassing process during the manufacturing of a secondary battery, wherein electrodes and separators are alternately stacked in the electrode assembly; and a support configured to support the pressing roller, wherein the pressing roller presses the main body of the bag accommodating the electrode assembly such that a portion of the main body other than the edge is pressed.

[0015] Advantageous Effects

[0016] According to the present invention, the main body of the bag can be pressed through the pressing process. Here, the main body of the bag can be pressed along the entire length direction of the battery cell by the pressing roller, so that the internal gas of the electrode assembly accommodated in the main body can be easily discharged to the outside of the electrode assembly.

[0017] In addition, when a portion of the main body other than the edge is pressed by the pressing roller, the internal gas between the electrode and the separator at the central portion in the electrode assembly can be easily discharged to the outside of the electrode assembly through the edge of the electrode assembly. Therefore, it is possible to prevent the phenomenon of gas remaining in the electrode assembly to form a gas trap, thereby preventing lithium (Li) from precipitating during subsequent charge / discharge processes. In addition, the edge of the electrode assembly that is easily broken or damaged is not pressed, thereby preventing the electrode assembly from being damaged due to the pressing process. Description of the Drawings

[0018] Figure 1 It is a plan view illustrating an accommodation process in a method of manufacturing a secondary battery according to an embodiment of the present invention.

[0019] Figure 2 It is a plan view illustrating an accommodation process in a method of manufacturing a secondary battery according to an embodiment of the present invention.

[0020] Figure 3 It is a perspective view illustrating a pressing process in a method of manufacturing a secondary battery according to an embodiment of the present invention.

[0021] Figure 4 It is a perspective view illustrating a pressing process in a method of manufacturing a secondary battery according to an embodiment of the present invention.

[0022] Figure 5 It is a front view illustrating a pressing process in a method of manufacturing a secondary battery according to an embodiment of the present invention.

[0023] Figure 6 It is a plan view of a secondary battery in a method of manufacturing a secondary battery according to an embodiment of the present invention.

[0024] Figure 7 It is a front view of a pressing process in a method of manufacturing a secondary battery according to another embodiment of the present invention.

[0025] Figure 8 It is a front view of a pressing process in a method of manufacturing a secondary battery according to still another embodiment of the present invention.

[0026] Figure 9 It is a plan view of a state in which gas inside a secondary battery manufactured by a method of manufacturing a secondary battery according to Manufacturing Example 1 of the present invention is removed.

[0027] Figure 10 It is a plan view of a state in which gas inside a secondary battery manufactured by a method of manufacturing a secondary battery according to Comparative Example 1 of the present invention is removed.

[0028] Figure 11 It is a plan view of a state in which gas inside a secondary battery manufactured by a method of manufacturing a secondary battery according to Comparative Example 2 of the present invention is removed. Detailed Description

[0029] The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. It should be noted that, as much as possible, the same reference numerals are used to label the components in the drawings of the present application, even if these components are shown in other drawings. In addition, the present invention may be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. In the following description of the present invention, detailed descriptions of related arts that may unnecessarily obscure the gist of the present invention will be omitted.

[0030] Method for manufacturing a secondary battery according to an embodiment

[0031] Figure 1 is a plan view illustrating a receiving process in a method of manufacturing a secondary battery according to an embodiment of the present invention, Figure 2 is a plan view illustrating a receiving process in a method of manufacturing a secondary battery according to an embodiment of the present invention, Figure 3 is a perspective view illustrating a pressing process in a method of manufacturing a secondary battery according to an embodiment of the present invention, Figure 4 is a perspective view illustrating a pressing process in a method of manufacturing a secondary battery according to an embodiment of the present invention. Here, Figure 4 is when viewed in a different direction from Figure 3 a perspective view.

[0032] Referring to Figures 1 to 4 , a method of manufacturing a secondary battery according to an embodiment of the present invention includes: a receiving process of receiving an electrode assembly 110 in a pouch 120 to form a battery cell 100; an activation process of activating the battery cell 100; a pressing process of pressing the battery cell 100; and a degassing process of discharging internal gas of the battery cell 100. In addition, a method of manufacturing a secondary battery according to an embodiment of the present invention may further include: an aging process of allowing the battery cell 100 to undergo a predetermined time; and a sealing process of sealing the pouch 120.

[0033] More specifically, referring to Figure 1 , a battery cell 100 includes a pouch 120 and an electrode assembly 110 received in a receiving portion 121 of the pouch 120. Here, the electrode assembly 110 may include electrode leads 111 and 112 electrically connected to the electrodes.

[0034] The electrode assembly 110 may be a power generation element capable of being charged and discharged and may be formed by alternately stacking electrodes and a separator.

[0035] The electrodes may be composed of a positive electrode and a negative electrode. At this time, the electrode assembly 110 may have a structure in which a positive electrode / separator / negative electrode are alternately stacked.

[0036] For example, in a plan view, the negative electrode may be formed to be larger than the positive electrode. Here, for example, the negative electrode may be formed such that its length and width are respectively 0.5 mm to 1.5 mm larger than those of the positive electrode. Here, more specifically, for example, the negative electrode may be formed such that its length and width are respectively approximately 1 mm larger than those of the positive electrode. That is to say, when the positive electrode, the separator, and the negative electrode are stacked, the end portion of the negative electrode in the lateral direction may protrude approximately 1 mm further than the end portion of the positive electrode.

[0037] In addition, the electrode leads 111 and 112 may include a positive electrode lead 111 connected to the positive electrode and a negative electrode lead 112 connected to the negative electrode.

[0038] The positive electrode may include a positive electrode current collector and a positive electrode active material stacked on the positive electrode current collector.

[0039] The positive electrode current collector may be made of aluminum foil.

[0040] The positive electrode active material may include lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture containing at least one of the above materials.

[0041] The negative electrode may include a negative electrode current collector and a negative electrode active material stacked on the negative electrode current collector.

[0042] The negative electrode current collector may be made of a foil made of a copper (Cu) material, for example.

[0043] The negative electrode active material may be a compound or mixture containing a graphite-based material.

[0044] The separator is made of an insulating material to electrically insulate the positive electrode and the negative electrode from each other. Here, the separator may be made of a polyolefin resin film such as polyethylene or polypropylene having microporosity.

[0045] Refer to Figure 1 and Figure 2 , in the accommodating process, the electrode assembly 110, the electrolyte, and one side portion of each of the electrode leads 111 and 112 connected to the electrodes may be accommodated in the accommodating portion 121 formed in the bag 120 to form the battery cell 100.

[0046] In addition, in the accommodating process, the other side portion of each of the electrode leads 111 and 112 may be accommodated to protrude outside the bag 120.

[0047] Here, the pouch 120 may include: a main body 123 having a receiving portion 121 formed to receive the electrode assembly 110; and an airbag portion 122 extending from the receiving portion 121 to collect gas generated in the receiving portion 121. In addition, the airbag portion 122 may extend in the full width direction W of the battery cell 100. Here, the full width direction W of the battery cell 100 may be perpendicular to the full length direction T, which is the protruding direction of the electrode leads 111 and 112 in the plan view. In this case, for example, the electrode assembly 110 may have a length greater than the width. That is, the electrode assembly 110 may be formed such that the length of the electrode assembly 110 in the full length direction T is greater than the width of the electrode assembly 110 in the full width direction W.

[0048] In the activation process, the battery cell 100 is charged to be activated. Here, in the activation process, the battery cell 100 may be charged by connecting power to the electrode leads 111 and 112 of the battery cell 100.

[0049] Figure 5 It is a front view illustrating the pressing process in the method of manufacturing a secondary battery according to an embodiment of the present invention.

[0050] Refer to Figures 4 to 5 , after the activation process, in the pressing process, the battery cell 100 is sequentially pressed by the pressing roller 10 to perform roll press.

[0051] In addition, in the pressing process, the battery cell 100 may be rolled along the full length direction T of the battery cell 100, that is, the protruding direction of the electrode leads 111 and 112.

[0052] In the pressing process, the main body 123 of the pouch 120 may be pressed.

[0053] In the pressing process, after the battery cell 100 is placed between a pair of pressing rollers 10, the pair of pressing rollers 10 may sequentially press two surfaces of the battery cell 100. Here, the pressing roller 10 may be in line contact with the battery cell 100. Thus, when the battery cell 100 is pressed while the pressing roller 10 is rolling, a linear pressure is sequentially applied to the outer surface of the battery cell 100. Thus, the gas located inside the electrode assembly 110 can be easily discharged to the outside of the electrode assembly 110.

[0054] Here, a pair of pressing rollers 10 may include: a first roller 11 for pressing the upper part of the battery cell 100, and a second roller 12 for pressing the lower part of the battery cell 100. In addition, the first roller 11 and the second roller 12 may be supported by supports 13 and 14. At this time, in the pressing process, the support 13 supporting the first roller 11 may be vertically moved by a moving device, so that the upper part of the battery cell 100 can be pressed by the first roller 11. Here, the moving device may be, for example, a pneumatic or hydraulic actuator.

[0055] In the pressing process, for example, the tab or pouch 120 of the battery cell 100 may be held and fixed by a fixing device to press the battery cell 100 while the pressing roller 10 moves. In this case, the fixing device may be, for example, a fixing jig (Zig).

[0056] In addition, as another example of the pressing process, the battery cell 100 may be input between a pair of pressing rollers 10 to be pressed.

[0057] In addition, in the pressing process, a pair of pressing rollers 10 may be set as one roller set, or one or more roller sets may be set.

[0058] In the pressing process, a pair of pressing rollers 10 may be set in a horizontal position.

[0059] In addition, in the pressing process, the gap between a pair of pressing rollers 10 may be adjusted. Here, in the pressing process, the distance between a pair of pressing rollers 10 may be maintained within a predetermined gap range.

[0060] In addition, in the pressing process, the pressing force applied to the battery cell 100 through the pressing rollers 10 may be adjusted. Here, in the pressing process, the pressing force applied to the battery cell 100 may be maintained within a predetermined pressure range. At this time, the pressing process may be performed such that the range of the pressing force of the pressing roller 10 for pressing the battery cell 100 is 10 kgf to 150 kgf. In addition, the load applied to the battery cell 100 can be detected by a load cell 15 provided on the support 14 supporting the pressing roller 10. Here, for example, the load cell 15 may be provided on the support 14 supporting the second roller 12 disposed below the battery cell 100.

[0061] In the pressing process, the part of the main body 123 of the pouch 120 other than the edges in the full width direction W of the battery cell 100 may be pressed.

[0062] In addition, in the pressing process, the pressing rollers 10 may be formed such that the diameter of each of the both side portions 11d and 12d is smaller than the diameter of each central portion 11a and 12a.

[0063] In this case, in the pressing process, the length b of the central portion of the pressing roller 10 can be set to be less than the width a of the main body 123. That is, in the pressing process, the length b of the central portion of the pressing roller 10 parallel to the full width direction W of the battery cell 100 can be set to be less than the width a of the main body 123 of the bag 120 parallel to the full width direction W of the battery cell 100, so that the portion of the main body 123 other than the edges is pressed. At this time, the width a of the main body 123 can be, for example, the width of the bottom surface of the accommodating portion 121 in the bag 120. Here, the width a of the main body 123 of the bag 120 can correspond to, for example, the width of the electrode assembly 110.

[0064] Here, the both side portions 11d and 12d of the pressing roller 10 can include a side portion 11b and 12b provided at one side in the full width direction W of the battery cell 100 and a side portion 11c and 12c provided at the other side.

[0065] In addition, in the pressing process, each of the both side portions 11d and 12d of the pressing roller 10 can be formed to have a diameter that gradually decreases toward the end of the pressing roller.

[0066] Here, in the pressing process, the outer surface of each of the both side portions 11d and 12d of the pressing roller 10 can have a curvature that is rounded from each central portion 11a and 12a toward each end. That is, in the pressing roller 10, a curvature can be formed at each corner portion of each of the both side portions 11d and 12d in the full width direction W of the battery cell 100. Thus, in the electrode assembly 110 accommodated in the main body 123, the central portion other than the edges in the full width direction W of the battery cell 100 can be pressed by the central portions 11a and 12a of the pressing roller 10. Thus, the gas located in the central portion of the electrode assembly 110 can move to the edge of the electrode assembly 110 and then be discharged to the outside of the electrode assembly 110. Here, the gas discharged to the outside of the electrode assembly 110 can be provided in the accommodating portion 121 or the air bag portion 122 in the bag 120 and then discharged to the outside of the bag 120 through a degassing process.

[0067] At this time, the rounded curvature formed on the outer surface of each of the both side portions 11d and 12d of the pressing roller 10 can be formed to have a curvature radius R of 5 mm to 50 mm.

[0068] Therefore, the curvature radius R is formed to be 5 mm or more as the lower limit value to prevent indentation on the battery and also prevent the battery from being damaged by the edges of the pressing roller 10. In addition, since the curvature radius R is formed to be 50 mm or less as the upper limit value, the pressing effect for removing the gas at the outer shell of the battery is not deteriorated.

[0069] After the activation process, in the aging process, the battery cell 100 can undergo a predetermined time. Here, in the aging process, the battery cell 100 can undergo a predetermined time at room temperature and high temperature. In this case, the aging process can be performed before the degassing process.

[0070] The pressing process can be performed during the aging process.

[0071] Figure 6 is a plan view of a secondary battery in a method of manufacturing a secondary battery according to an embodiment of the present invention.

[0072] Refer to Figure 6 , after the degassing process, in the sealing process, the outer peripheral surface of the bag 120 can be sealed to manufacture the secondary battery 100'.

[0073] In this case, in the sealing process, the air bag portion 122 can be cut and removed, and then the removed portion can be sealed by heat fusion to seal the bag 120.

[0074] Refer to Figure 1 and Figure 4 , in the method of manufacturing a secondary battery according to the present invention configured as described above, the main body 123 of the bag 120 can be pressed by the pressing process. Here, the main body 123 can be pressed along the entire length direction T of the battery cell 100 by the pressing roller 10, so that the internal gas of the electrode assembly 110 accommodated in the main body 123 can be easily discharged to the outside of the electrode assembly 110.

[0075] Here, when the portion of the main body 123 other than the edge is pressed by the pressing roller 10, the central portion of the electrode assembly 110 accommodated in the main body 123 can be pressed, so that the internal gas between the electrode and the separator at the central portion of the electrode assembly 110 can be easily discharged to the outside of the electrode assembly 110 through the edge of the electrode assembly 110. Therefore, the phenomenon of gas remaining in the electrode assembly 110 to form a gas trap can be prevented, thereby preventing lithium (Li) from precipitating during subsequent charge / discharge processes. In addition, the edge of the electrode assembly 110 that is easily broken or damaged is not pressed, thereby preventing the electrode assembly 110 from being damaged due to the pressing process.

[0076] Method for manufacturing a secondary battery according to another embodiment

[0077] Hereinafter, a method of manufacturing a secondary battery according to another embodiment of the present invention will be described.

[0078] Figure 7 is a front view illustrating a pressing process in a method of manufacturing a secondary battery according to another embodiment of the present invention.

[0079] Refer toFigure 1 , Figure 2 and Figure 7 , a method of manufacturing a secondary battery according to another embodiment of the present invention includes: an accommodating step of accommodating the electrode assembly 110 in the pouch 120 to form the battery cell 100; an activating step of activating the battery cell 100; a pressing step of pressing the battery cell 100; and a degassing step of discharging the internal gas of the battery cell 100.

[0080] In addition, a method of manufacturing a secondary battery according to another embodiment of the present invention may further include: an aging step of subjecting the battery cell 100 to a predetermined time; and a sealing step of sealing the pouch 120.

[0081] The method of manufacturing a secondary battery according to another embodiment of the present invention is different from the method of manufacturing a secondary battery according to the foregoing embodiment of the present invention in the implementation manner of the pressing step. Therefore, the content that is repeated between this embodiment and the foregoing embodiment will be omitted or briefly described, and the differences between them will be mainly described.

[0082] More specifically, in the method of manufacturing a secondary battery according to another embodiment of the present invention, in the accommodating step, one side of each of the electrode assembly 110, the electrolyte, and the electrode leads 111 and 112 connected to the electrodes may be accommodated in the accommodating portion 121 formed in the pouch 120 to form the battery cell 100.

[0083] In addition, in the accommodating step, the other side of each of the electrode leads 111 and 112 may be accommodated to protrude outside the pouch 120.

[0084] Here, the pouch 120 may include: a main body 123 formed with the accommodating portion 121 for accommodating the electrode assembly 110; and an air bag portion 122 extending from the accommodating portion 121 to collect the gas generated in the accommodating portion 121. In addition, the air bag portion 122 may extend in the full width direction W of the battery cell 100.

[0085] After the activating step, in the pressing step, the battery cell 100 is sequentially pressed by the pressing roller 20 to perform roll press.

[0086] In addition, in the pressing step, the battery cell 100 may be rolled in the longitudinal direction T of the battery cell 100, that is, the protruding direction of the electrode leads 111 and 112. Here, in the pressing step, the main body 123 of the pouch 120 may be pressed.

[0087] In addition, in the pressing process, after placing the battery cell 100 between a pair of pressing rollers 20, the pair of pressing rollers 20 can sequentially press two surfaces of the battery cell 100. Here, the pressing rollers 20 can be in line contact with the battery cell 100. Thus, when pressing the battery cell 100 while the pressing rollers 20 are rolling, a linear pressure is sequentially applied to the outer surface of the battery cell 100. Consequently, the gas located inside the electrode assembly 110 can be easily discharged to the outside of the electrode assembly 110. Here, the pair of pressing rollers 20 can include: a first roller 21 for pressing the upper part of the battery cell 100, and a second roller 22 for pressing the lower part of the battery cell 100.

[0088] In the pressing process, the pair of pressing rollers 20 can be set in a horizontal position.

[0089] In addition, in the pressing process, a portion of the main body 123 of the pressing bag 120 other than the edges in the full-width direction W can be pressed.

[0090] In addition, in the pressing process, the length c of the pressing roller 20 can be set to be less than the width a of the main body 123.

[0091] That is, in the pressing process, the length c of the pressing roller 20 parallel to the full-width direction W of the battery cell 100 can be set to be less than the width a of the main body 123 of the bag 120 parallel to the full-width direction W of the battery cell 100, so that a portion of the main body 123 other than the edges is pressed.

[0092] Consequently, in the electrode assembly 110 accommodated in the main body 123, a central portion other than the edges in the full-width direction W of the battery cell 100 can be pressed by the pressing roller 20. Thus, the gas located in the central portion of the electrode assembly 110 can move to the edges of the electrode assembly 110 and then be discharged to the outside of the electrode assembly 110.

[0093] The length c of the pressing roller 20 can be formed, for example, to be 2 mm to 10 mm smaller than the width a of the main body 123 of the bag 120.

[0094] Consequently, the length c of the pressing roller 20 can be formed to be 2 mm or more smaller than the width a of the main body 123 as a lower limit value to prevent damage to the outer shell of the electrode assembly 110. That is, when pressing the electrode assembly 110 in which the negative electrode is formed larger than the positive electrode in the stacking direction, damage to the negative electrode by the edge of the positive electrode can be prevented. In addition, the length c of the pressing roller 20 can be formed to be 10 mm or less smaller than the width a of the main body 123 as an upper limit value to prevent deterioration of the gas removal effect at the outer shell of the battery.

[0095] Method for manufacturing a secondary battery according to still another embodiment

[0096] Hereinafter, a method of manufacturing a secondary battery according to another embodiment of the present invention will be described.

[0097] Figure 8 is a front view illustrating a pressing process in a method of manufacturing a secondary battery according to another embodiment of the present invention.

[0098] Referring to Figure 1 、 Figure 2 and Figure 8 ,a method of manufacturing a secondary battery according to another embodiment of the present invention includes: an accommodating process of accommodating an electrode assembly 110 in a bag 120 to form a battery cell 100; an activating process of activating the battery cell 100; a pressing process of pressing the battery cell 100; and a degassing process of discharging internal gas of the battery cell 100.

[0099] In addition, a method of manufacturing a secondary battery according to another embodiment of the present invention may further include: an aging process of allowing the battery cell 100 to undergo a predetermined time; and a sealing process of sealing the bag 120.

[0100] A method of manufacturing a secondary battery according to another embodiment of the present invention is different from a method of manufacturing a secondary battery according to the foregoing embodiment of the present invention in the implementation manner of the pressing process. Therefore, the content that is repeated between this embodiment and the foregoing embodiment will be omitted or briefly described, and the differences between them will be mainly described.

[0101] More specifically, in a method of manufacturing a secondary battery according to another embodiment of the present invention, in the accommodating process, each of the electrode assembly 110, the electrolyte, and electrode leads 111 and 112 connected to the electrodes may be accommodated in an accommodating portion 121 formed in the bag 120 to form the battery cell 100.

[0102] In addition, in the accommodating process, the other side of each of the electrode leads 111 and 112 may be accommodated to protrude outside the bag 120.

[0103] Here, the bag 120 may include: a main body 123 having an accommodating portion 121 formed therein for accommodating the electrode assembly 110; and an air bag portion 122 extending from the accommodating portion 121 to collect gas generated in the accommodating portion 121. In addition, the air bag portion 122 may extend in the full width direction W of the battery cell 100.

[0104] After the activating process, in the pressing process, the battery cell 100 is sequentially pressed by a pressing roller 30 to perform roll press.

[0105] In addition, in the pressing process, the battery cell 100 can be rolled along the entire length direction T of the battery cell 100, that is, the protruding direction of the electrode leads 111 and 112. Here, in the pressing process, the main body 123 of the pressing bag 120 can be pressed.

[0106] In addition, in the pressing process, after the battery cell 100 is placed between a pair of pressing rollers 30, the pair of pressing rollers 30 can sequentially press two surfaces of the battery cell 100. Here, the pressing roller 30 can be in line contact with the battery cell 100. Thus, when the battery cell 100 is pressed while the pressing roller 30 is rolling, a linear pressure is sequentially applied to the outer surface of the battery cell 100. Thus, the gas located inside the electrode assembly 110 can be easily discharged to the outside of the electrode assembly 110. Here, the pair of pressing rollers 30 can include: a first roller 31 for pressing the upper part of the battery cell 100, and a second roller 32 for pressing the lower part of the battery cell 100.

[0107] In addition, in the pressing process, the pair of pressing rollers 30 can be set in a horizontal position.

[0108] In addition, in the pressing process, the part of the main body 123 of the pressing bag 120 except for the edges in the full width direction W can be pressed.

[0109] In addition, in the pressing process, each of the both side portions 31d and 32d of the pressing roller 30 can be formed to have a diameter gradually decreasing toward the end of the pressing roller. Here, the both side portions 31d and 32d of the pressing roller 30 can include a side portion 31b and 32b provided at one side in the full width direction W of the battery cell 100 and a side portion 31c and 32c provided at the other side. In this case, in the pressing process, the length d of each central portion 31a and 32a of the pressing roller 30 can be set to be smaller than the width a of the main body 123.

[0110] In addition, in the pressing process, each of the both side portions 31d and 32d of the pressing roller 30 can be chamfered. That is, in the pressing process, the corner portion of the outer peripheral surface of each of the both side portions 31d and 32d of the pressing roller 30 can be formed to have an inclined surface with a diameter gradually decreasing toward the end of the pressing roller.

[0111] Thus, in the electrode assembly 110 accommodated in the main body 123, the central portion except for the edges in the full width direction W of the battery cell 100 can be pressed by the pressing roller 30. Thus, the gas located in the central portion of the electrode assembly 110 can move to the edge of the electrode assembly 110 and then be discharged to the outside of the electrode assembly 110.

[0112] Device for manufacturing a secondary battery according to an embodiment

[0113] Hereinafter, an apparatus for manufacturing a secondary battery according to an embodiment of the present invention will be described.

[0114] Referring Figure 1 and Figure 4 FIGS. and, an apparatus for manufacturing a secondary battery according to an embodiment of the present invention includes: a pressing roller 10 that presses a battery cell 100 in which an electrode assembly 110 and an electrolyte are accommodated in a bag 120; and a support that supports the pressing roller 10. The pressing roller 10 performs rolling on the battery cell 100 along the entire length direction T of the battery cell 100 to manufacture a secondary battery.

[0115] The apparatus for manufacturing a secondary battery according to an embodiment of the present invention relates to an apparatus for manufacturing a secondary battery applied to the method for manufacturing a secondary battery according to the above-described embodiment. Accordingly, the content repeated with the method for manufacturing a secondary battery according to the present embodiment and the foregoing embodiment will be omitted or briefly described, and the differences therebetween will be mainly described.

[0116] More specifically, the pressing roller 10 may sequentially press the battery cell 100 in which the electrode assembly 110 and the electrolyte are accommodated in the bag 120 after the activation process and before the degassing process to perform rolling.

[0117] Here, in the electrode assembly 110, the electrodes and the separator may be stacked alternately with each other.

[0118] One side of each of the electrode leads 111 and 112 connected to the electrodes may be accommodated in the bag 120, and the other side may protrude to the outside of the bag 120. At this time, the pressing roller 10 may perform rolling along the entire length direction T of the battery cell 100, that is, the protruding direction of the electrode leads 111 and 112.

[0119] In addition, the bag 120 may include: a main body 123 having a receiving portion 121 formed therein for receiving the electrode assembly 110; and a gas bag portion 122 extending from the receiving portion 121 to collect gas generated in the receiving portion 121. In addition, the gas bag portion 122 may extend in the entire width direction W of the battery cell 100. Here, the entire width direction W of the battery cell 100 may be perpendicular to the entire length direction T, and the entire length direction T is the protruding direction of the electrode leads 111 and 112 in a plan view.

[0120] In addition, the pressing roller 10 may be provided as a pair. After the battery cell 100 is placed between the pair of pressing rollers 10, the pair of pressing rollers 10 may sequentially press two surfaces of the battery cell 100. Here, the pressing roller 10 may be in line contact with the battery cell 100. Accordingly, when the battery cell 100 is pressed while the pressing roller 10 is rolling, a linear pressure is sequentially applied to the outer surface of the battery cell 100. Thus, the gas located inside the electrode assembly 110 can be easily discharged to the outside of the electrode assembly 110.

[0121] Here, a pair of pressing rollers 10 may include: a first roller 11 for pressing the upper part of the battery cell 100, and a second roller 12 for pressing the lower part of the battery cell 100.

[0122] The pressing roller 10 may press a part of the main body 123 of the bag 120 other than the edges in the entire width direction W of the battery cell 100. To this end, the pressing roller 10 may be formed such that the diameter of each of the both side portions 11d and 12d is smaller than the diameter of each central portion 11a and 12a.

[0123] Here, the length b of the central portion of the pressing roller 10 may be set to be smaller than the width a of the main body 123. That is, the length b of the central portion of the pressing roller 10 parallel to the entire width direction W of the battery cell 100 may be set to be smaller than the width a of the main body 123 of the bag 120 parallel to the entire width direction W of the battery cell 100, so that a part of the main body 123 other than the edges is pressed.

[0124] Here, the both side portions 11d and 12d of the pressing roller 10 may include a first side portion 11b and 12b provided at one side in the entire width direction W of the battery cell 100 and a second side portion 11c and 12c provided at the other side.

[0125] In addition, each of the both side portions 11d and 12d of the pressing roller 10 may be formed to have a diameter gradually decreasing toward the end of the pressing roller.

[0126] Thus, in the electrode assembly 110 accommodated in the main body 123, a central portion other than the edges in the entire width direction W of the battery cell 100 may be pressed by the central portions 11a and 12a of the pressing roller 10. Thus, gas located in the central portion of the electrode assembly 110 may move to the edges of the electrode assembly 110 and then be discharged to the outside of the electrode assembly 110. Here, the gas discharged to the outside of the electrode assembly 110 may be provided in the accommodation part 121 or the air bag part 122 in the bag 120 and then discharged to the outside of the bag 120 through a degassing process. Here, the outer surface of each of the both side portions 11d and 12d of the pressing roller 10 may have a curvature rounded from each central portion 11a and 12a toward each end. That is, in the pressing roller 10, a curvature may be formed at each corner of each of the both side portions 11d and 12d in the entire width direction W of the battery cell 100.

[0127] Thus, in the electrode assembly 110 accommodated in the main body 123, the central portions of the battery cells 100 except for the edges in the full width direction W of the battery cells 100 can be pressed by the central portions 11a and 12a of the pressing roller 10. Thus, the gas in the central portion of the electrode assembly 110 can move to the edge of the electrode assembly 110 and then be discharged to the outside of the electrode assembly 110. Here, the gas discharged to the outside of the electrode assembly 110 can be provided in the accommodating portion 121 or the air bag portion 122 within the bag 120 and then be discharged to the outside of the bag 120 through a degassing process.

[0128] At this time, the rounded curvature formed on the outer surface of each of the both side portions 11d and 12d of the pressing roller 10 can be formed to have a radius of curvature R of 5 mm to 50 mm.

[0129] Thus, the radius of curvature R is formed to be 5 mm or more as the lower limit value to prevent indentations on the battery and also prevent the battery from being damaged by the edges of the pressing roller 10. In addition, since the radius of curvature R is formed to be 50 mm or less as the upper limit value, the pressing effect of removing the gas at the outer shell of the battery is not deteriorated.

[0130] The support members 13 and 14 can support the pressing roller 10. In addition, the support members 13 and 14 can support the first roller 11 and the second roller 12 of the pressing roller 10, respectively. At this time, the support member 13 that supports the first roller 11 can be vertically moved by a moving device, and thus the upper portion of the battery cell 100 can be pressed by the first roller 11. Here, the moving device can be, for example, a pneumatic or hydraulic actuator.

[0131] Load sensors 15 can be provided on each of the support members 13 and 14 to detect the load applied to the battery cell 100. Here, for example, the load sensor 15 can be provided on the support member 14 that supports the second roller 12 disposed below the battery cell 100.

[0132] Device for manufacturing a secondary battery according to another embodiment

[0133] Hereinafter, an apparatus for manufacturing a secondary battery according to another embodiment of the present invention will be described.

[0134] Referring to Figure 1 、 Figure 2 and Figure 7 An apparatus for manufacturing a secondary battery according to another embodiment of the present invention includes: a pressing roller 20 that presses a battery cell 100 in which an electrode assembly 110 and an electrolyte are accommodated in a bag 120; and a support member that supports the pressing roller 20. The pressing roller 20 performs rolling on the battery cell 100 along the entire length direction T of the battery cell 100 to manufacture a secondary battery.

[0135] The device for manufacturing a secondary battery according to another embodiment of the present invention is different from the device for manufacturing a secondary battery according to the foregoing embodiment of the present invention in the configuration of the pressing roller 20. Accordingly, the content that is repeated between this embodiment and the foregoing embodiment will be omitted or briefly described, and the differences therebetween will be mainly described.

[0136] More specifically, in the device for manufacturing a secondary battery according to another embodiment of the present invention, the pressing roller 20 may sequentially press the battery cell 100 in which the electrode assembly 110 and the electrolyte are accommodated in the bag 120 after the activation process and before the degassing process to perform rolling.

[0137] Herein, in the electrode assembly 110, the electrodes and the separator may be alternately stacked with each other.

[0138] One side of each of the electrode leads 111 and 112 connected to the electrodes may be accommodated in the bag 120, and the other side may protrude to the outside of the bag 120. At this time, the pressing roller 20 may perform rolling along the entire length direction T of the battery cell 100, that is, the protruding direction of the electrode leads 111 and 112.

[0139] In addition, the bag 120 may include: a main body 123 having a receiving portion 121 formed therein for receiving the electrode assembly 110; and a gas bag portion 122 extending from the receiving portion 121 to collect the gas generated in the receiving portion 121. In addition, the gas bag portion 122 may extend in the entire width direction W of the battery cell 100. Herein, the entire width direction W of the battery cell 100 may be perpendicular to the entire length direction T, and the entire length direction T is the protruding direction of the electrode leads 111 and 112 in the plan view.

[0140] In addition, the pressing roller 20 may be provided as a pair. After the battery cell 100 is placed between the pair of pressing rollers 20, the pair of pressing rollers 20 may sequentially press the two surfaces of the battery cell 100. Herein, the pressing roller 20 may be in line contact with the battery cell 100. Accordingly, when the battery cell 100 is pressed while the pressing roller 20 is rolling, a linear pressure is sequentially applied to the outer surface of the battery cell 100. Thus, the gas located inside the electrode assembly 110 can be easily discharged to the outside of the electrode assembly 110.

[0141] Herein, the pair of pressing rollers 20 may include: a first roller 11 for pressing the upper portion of the battery cell 100, and a second roller 12 for pressing the lower portion of the battery cell 100.

[0142] The pressing roller 20 may press the portion of the main body 123 of the bag 120 except for the edges in the entire width direction W of the battery cell 100.

[0143] In addition, the length c of the pressing roller 20 may be set to be less than the width a of the main body 123.

[0144] That is, the length c of the pressing roller 20 parallel to the full-width direction W of the battery cell 100 can be set to be less than the width a of the main body 123 of the bag 120 parallel to the full-width direction W of the battery cell 100, so that the portion of the main body 123 other than the edge is pressed.

[0145] Thus, in the electrode assembly 110 accommodated in the main body 123, the central portion other than the edge in the full-width direction W of the battery cell 100 can be pressed by the pressing roller 20. Thus, the gas in the central portion of the electrode assembly 110 can move to the edge of the electrode assembly 110 and then be discharged to the outside of the electrode assembly 110.

[0146] The length c of the pressing roller 20 can be formed, for example, to be 2 mm to 10 mm smaller than the width a of the main body 123 of the bag 120.

[0147] Thus, the length c of the pressing roller 20 can be formed to be 2 mm or more smaller than the width a of the main body 123 as a lower limit value to prevent damage to the outer shell of the electrode assembly 110. When pressing the electrode assembly 110 in which the negative electrode is formed larger than the positive electrode in the stacking direction, damage to the negative electrode by the edge of the positive electrode can be prevented. In addition, the length c of the pressing roller 20 can be formed to be 10 mm or less smaller than the width a of the main body 123 as an upper limit value to prevent deterioration of the gas removal effect at the outer shell of the battery.

[0148] The support members 13 and 14 can support the pressing roller 20. In addition, the support members 13 and 14 can support the first roller 21 and the second roller 22 of the pressing roller 20, respectively. At this time, the support member 13 that supports the first roller 21 can be vertically moved by a moving device, so that the upper portion of the battery cell 100 can be pressed by the first roller 21.

[0149] Device for manufacturing a secondary battery according to still another embodiment

[0150] Hereinafter, an apparatus for manufacturing a secondary battery according to another embodiment of the present invention will be described.

[0151] Referring to Figure 1 、 Figure 2 and Figure 8 An apparatus for manufacturing a secondary battery according to another embodiment of the present invention includes: a pressing roller 30 that presses a battery cell 100 in which an electrode assembly 110 and an electrolyte are accommodated in a bag 120; and a support member that supports the pressing roller 30. The pressing roller 30 performs rolling on the battery cell 100 along the entire length direction T of the battery cell 100 to manufacture a secondary battery.

[0152] The device for manufacturing a secondary battery according to another embodiment of the present invention is different from the device for manufacturing a secondary battery according to the foregoing embodiment in the configuration of the pressing roller 30. Accordingly, the content that is repeated between this embodiment and the foregoing embodiment will be omitted or briefly described, and the differences therebetween will be mainly described.

[0153] More specifically, in the device for manufacturing a secondary battery according to another embodiment of the present invention, the pressing roller 30 may sequentially press the battery cell 100 in which the electrode assembly 110 and the electrolyte are accommodated in the bag 120 after the activation process and before the degassing process to perform rolling.

[0154] Herein, in the electrode assembly 110, the electrodes and the separator may be stacked alternately with each other.

[0155] One side of each of the electrode leads 111 and 112 connected to the electrodes may be accommodated in the bag 120, and the other side may protrude to the outside of the bag 120. At this time, the pressing roller 30 may perform rolling along the entire length direction T of the battery cell 100, that is, the protruding direction of the electrode leads 111 and 112.

[0156] In addition, the bag 120 may include: a main body 123 formed with a receiving portion 121 for receiving the electrode assembly 110; and an air bag portion 122 extending from the receiving portion 121 to collect the gas generated in the receiving portion 121. In addition, the air bag portion 122 may extend in the entire width direction W of the battery cell 100. Herein, the entire width direction W of the battery cell 100 may be perpendicular to the entire length direction T, and the entire length direction T is the protruding direction of the electrode leads 111 and 112 in the plan view.

[0157] In addition, the pressing roller 30 is provided as a pair. After the battery cell 100 is placed between the pair of pressing rollers 30, the pair of pressing rollers 30 may sequentially press the two surfaces of the battery cell 100. Herein, the pressing roller 30 may be in line contact with the battery cell 100. Accordingly, when the battery cell 100 is pressed while the pressing roller 30 is rolling, a linear pressure is sequentially applied to the outer surface of the battery cell 100. Thus, the gas located inside the electrode assembly 110 may be easily discharged to the outside of the electrode assembly 110.

[0158] Herein, the pair of pressing rollers 30 may include: a first roller 31 for pressing the upper portion of the battery cell 100, and a second roller 32 for pressing the lower portion of the battery cell 100.

[0159] The pressing roller 30 may press the portion of the main body 123 of the bag 120 except for the edges in the entire width direction W of the battery cell 100.

[0160] In addition, each of the both-side portions 31d and 32d of the pressing roller 30 may be formed to have a diameter gradually decreasing toward the end of the pressing roller. Herein, the both-side portions 31d and 32d of the pressing roller 30 may include a one-side portion 31b and 32b provided at one side in the full-width direction W of the battery cell 100 and a the-other-side portion 31c and 32c provided at the other side. At this time, the length d of each central portion 31a and 32a of the pressing roller 30 may be set to be smaller than the width a of the main body 123. Herein, the length d of each central portion 31a and 32a of the pressing roller 30 corresponding to the pressing length of the main body 123 of the pressing bag 120 may be formed, for example, to be 2 mm to 10 mm smaller than the width a of the main body 123 of the bag 120. In addition, each of the both-side portions 31d and 32d of the pressing roller 30 may be chamfered. That is, the corner portion of the outer peripheral surface of each of the both-side portions 31d and 32d of the pressing roller 30 may be formed to have an inclined surface with a diameter gradually decreasing toward the end of the pressing roller.

[0161] Accordingly, in the electrode assembly 110 accommodated in the main body 123, the central portion except for the edge in the full-width direction W of the battery cell 100 may be pressed by the pressing roller 30. Accordingly, the gas located in the central portion of the electrode assembly 110 may move to the edge of the electrode assembly 110 and then be discharged to the outside of the electrode assembly 110.

[0162] The supports 13 and 14 may support the pressing roller 30. In addition, the supports 13 and 14 may support the first roller 31 and the second roller 32 of the pressing roller 30, respectively. At this time, the support 13 supporting the first roller 31 may be vertically moved by a moving device, and thus the upper portion of the battery cell 100 may be pressed by the first roller 31.

[0163] <Manufacturing Example 1>

[0164] The following processes are performed to manufacture a secondary battery: an accommodation process of accommodating an electrode assembly in which electrodes and a separator are alternately stacked, an electrolyte, and one side portion of an electrode lead connected to the electrode in a bag to form a battery cell; an activation process of charging the battery cell to activate the battery cell; a pressing process of sequentially pressing the battery cell by a pressing roller after the activation process to roll the battery cell; and a degassing process of discharging the internal gas of the battery cell to the outside after the pressing process. Herein, in the accommodation process, the other side portion of the electrode lead is accommodated to protrude to the outside of the bag, and in the pressing process, rolling is performed along the entire length direction of the battery cell, that is, the protruding direction of the electrode lead.

[0165] <Comparative Example 1>

[0166] The same processes as in Manufacturing Example 1 are performed except that rolling is performed along the full-width direction of the battery cell in the pressing process.

[0167] <Comparative Example 2>

[0168] The same processes as in Manufacturing Example 1 were performed, except that the pressing process was performed after the degassing process.

[0169] <Test Example 1>

[0170] Figure 9 It is a plan view illustrating a state in which gas inside a secondary battery manufactured by the method for manufacturing a secondary battery according to Manufacturing Example 1 of the present invention has been removed. Figure 10 It is a plan view illustrating a state in which gas inside a secondary battery manufactured by the method for manufacturing a secondary battery according to Comparative Example 1 of the present invention has been removed. Figure 11 It is a plan view illustrating a state in which gas inside a secondary battery manufactured by the method for manufacturing a secondary battery according to Comparative Example 2 of the present invention has been removed.

[0171] Ultrasonic waves were applied to the secondary battery to measure the remaining amount of gas inside the secondary battery based on the degree of ultrasonic wave penetration.

[0172] In Figures 9 to 11 the area shown in red is the ultrasonic wave penetration area, and the area shown in blue is the ultrasonic wave non-penetration area. That is, the area where ultrasonic waves can penetrate is the area from which gas has been removed, and the area where ultrasonic waves cannot penetrate is the area where internal gas is present.

[0173] Referring to Figure 9 , in the case of Manufacturing Example 1, the ratio of the ultrasonic wave non-penetration area was 2.7%. Referring to Figure 10 , in Comparative Example 1, the ratio of the ultrasonic wave non-penetration area was 17.2%. Referring to Figure 11 , in Comparative Example 2, the ratio of the ultrasonic wave non-penetration area was 44.8%.

[0174] Therefore, it can be seen that in the case of Manufacturing Example 1, the ratio of the ultrasonic wave non-penetration area is 2.7%, so there is only a very small amount of internal gas. In the case of Comparative Example 1, the ratio of the ultrasonic wave non-penetration area is 17.2%, so there is a large amount of internal gas. In the case of Comparative Example 2, the ratio of the ultrasonic wave non-penetration area is 44.8%, so there is a large amount of internal gas.

[0175] As a result, it can be seen that compared with the technique of performing rolling along the entire width direction of the battery cell according to Comparative Example 1, in the technique of performing rolling along the entire length direction of the battery cell according to Manufacturing Example 1, the remaining amount of internal gas is significantly reduced.

[0176] In addition, it can be seen that, compared with the technique of performing rolling along the entire length direction of the battery cell after the degassing process according to Comparative Example 2, in the technique of performing rolling along the entire length direction of the battery cell before the degassing process according to Production Example 1, the remaining amount of internal gas is significantly reduced.

[0177] Although the present invention has been specifically shown and described with reference to the exemplary embodiments thereof, it should be understood that the scope of the present invention is not limited thereto. Those of ordinary skill in the art will understand that various changes in form and details may be made without departing from the spirit and scope of the present invention.

[0178] In addition, the protection scope of the present invention will be defined by the appended claims.

[0179] [Reference Signs Explanation]

[0180] 10, 20, 30: Pressing Roll

[0181] 11, 21, 31: First Roll

[0182] 12, 22, 32: Second Roll

[0183] 11a, 12a, 21a, 22a, 31a, 32a: Central Portion

[0184] 11b, 12b, 21b, 22b, 31b, 32b: One Side Portion

[0185] 11c, 12c, 21c, 22c, 31c, 32c: The Other Side Portion

[0186] 11d, 12d, 21d, 22d, 31d, 32d: Both Sides Portion

[0187] 13, 14: Support Member

[0188] 15: Load Cell

[0189] 100: Battery Cell

[0190] 100’: Secondary Battery

[0191] 110: Electrode Assembly

[0192] 111: Positive Electrode Lead

[0193] 112: Negative Electrode Lead

[0194] 120: Bag

[0195] 121: Accommodating Portion

[0196] 122: Gas Bag Portion

[0197] 123: Main Body

[0198] T: Along the entire length direction

[0199] W: Along the entire width direction.

Claims

1. A method for manufacturing a secondary battery, the method comprising: a housing step of housing in a bag an electrode assembly in which electrodes and separators are alternately stacked, an electrolyte, and one side portion of an electrode lead connected to the electrode to form a battery cell; an activation step of charging the battery cell to activate the battery cell; a pressing step of sequentially pressing the battery cell with a press roller after the activation step to roll the battery cell; and a degassing step of discharging internal gas of the battery cell to the outside after the pressing step, wherein, in the pressing step, the press roller presses a main body of the bag that houses the electrode assembly such that a portion of the main body other than an edge is pressed, so that a central portion of the electrode assembly is pressed while an edge of the electrode assembly is not pressed.

2. The method according to claim 1, wherein the bag includes: the main body having a housing portion for housing the electrode assembly; and an air bag portion extending from the housing portion to collect gas generated in the housing portion, wherein the other side portion of each electrode lead is housed to protrude outside the bag, and the air bag portion extends in a full width direction of the battery cell, the full width direction being perpendicular to a protruding direction of the electrode lead.

3. The method according to claim 2, wherein In the pressing step, after the battery cell is placed between a pair of press rollers, the pair of press rollers sequentially press two surfaces of the battery cell.

4. The method according to claim 2, wherein In the housing step, the other side portion of the electrode lead is housed to protrude outside the bag, and in the pressing step, rolling is performed along a full length direction of the battery cell, i.e., the protruding direction of the electrode lead.

5. The method according to claim 4, wherein, In the pressing step, rolling is performed on a portion of the main body other than an edge in the full width direction of the battery cell.

6. The method according to claim 5, wherein, In the pressing step, each press roller is formed such that a diameter of each of both side portions of the press roller is smaller than a diameter of a central portion of the press roller.

7. The method according to claim 6, wherein, In the pressing step, each of the both side portions of the press roller is formed to have a diameter gradually decreasing toward an end of the press roller.

8. The method according to claim 7, wherein In the pressing step, an outer surface of each of the both side portions of the press roller has a curvature rounded from the central portion toward the end.

9. The method according to claim 5, wherein In the pressing step, a length of the press roller is set to be smaller than a width of the main body.

10. The method according to claim 5, wherein, In the pressing step, each of the both side portions of the press roller is chamfered.

11. The method according to claim 1, further comprising: Subjecting the battery to an aging process for a predetermined time, wherein the pressing step is performed during the aging process.

12. An apparatus for manufacturing a secondary battery, the apparatus comprising: a press roller configured to sequentially roll a battery cell in which an electrode assembly and an electrolyte are housed in a bag after an activation step and before a degassing step during the manufacturing of a secondary battery, in which electrodes and separators are alternately stacked in the electrode assembly; and a support configured to support the press roller, Wherein the pressing roller presses the main body of the bag that houses the electrode assembly, such that a portion of the main body other than the edge is pressed, so that the central portion of the electrode assembly is pressed, while the edge of the electrode assembly is not pressed.

13. The apparatus according to claim 12, wherein the bag comprises: The main body formed with a receiving portion for receiving the electrode assembly; And An air bag portion extending from the receiving portion to collect gas generated in the receiving portion, Wherein the electrode assembly further includes an electrode lead having one side connected to each electrode and another side protruding outside the bag, and The air bag portion extends in the full width direction of the battery cell, and the full width direction is perpendicular to the protruding direction of the electrode lead.

14. The apparatus according to claim 13, wherein the pressing roller is provided as a pair, and After the battery cell is placed between the pair of pressing rollers, the pair of pressing rollers sequentially press two surfaces of the battery cell.

15. The apparatus according to claim 13, wherein the pressing roller rolls over the battery cell along the entire length direction of the battery cell, that is, the protruding direction of the electrode lead.

16. The apparatus according to claim 15, wherein In the pressing roller, the diameter of each of the two side portions of the pressing roller is smaller than the diameter of the central portion of the pressing roller, so as to press a portion of the main body other than the edge in the full width direction of the battery cell.

17. The apparatus according to claim 16, wherein the outer surface of each of the two side portions of the pressing roller has a curvature that is rounded from the central portion toward the end of the pressing roller.

18. The device according to claim 17, wherein, In the pressing roller, the curvature having a rounded shape formed on the outer surface of each of the two side portions has a curvature radius (R) of 5 mm to 50 mm.

19. The apparatus according to claim 13, wherein the pressing roller has a length smaller than the width of the main body, so as to press a portion of the main body other than the edge in the full width direction of the battery cell.

20. The apparatus according to claim 19, wherein the pressing roller has a length that is 2 mm to 10 mm smaller than the width of the main body.

21. The apparatus according to claim 13, wherein each of the two side portions of the pressing roller is chamfered, so as to press a portion of the main body other than the edge in the full width direction of the battery cell.

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