Reforming device and reforming method for electrode assembly

Abstract

Provided are a reforming device and a reforming method capable of reducing defects of a reforming process. The reforming device according to the present invention comprises: a reforming pin unit including a reforming pin which can be inserted into a hollow portion of an electrode assembly, and a driving unit which can perform a forward / backward operation and a raising / lowering operation of the reforming pin; and a rotating unit capable of rotating the electrode assembly around an axial direction of the hollow portion.

Description

Technical Field

[0001] The present disclosure relates to a reforming device and a reforming method for an electrode assembly, and more particularly, to a reforming device and a reforming method for a jellyroll-type electrode assembly for a cylindrical secondary battery. This application claims priority to Korean Patent Application No. 10-2022-0179765 filed in Korea on December 20, 2022 and Korean Patent Application No. 10-2023-0186226 filed in Korea on December 19, 2023, respectively, the disclosures of which are incorporated herein by reference. Background Art

[0002] With the technological development of mobile devices and the increase in demand for mobile devices, the demand for secondary batteries as energy sources has rapidly increased, and among the secondary batteries, lithium secondary batteries having high energy density and high discharge voltage have been largely studied, commercialized, and widely used.

[0003] According to the shape of a battery case, secondary batteries are classified into cylindrical batteries and prismatic batteries in which an electrode assembly is embedded in a cylindrical or rectangular metal can, and pouch-type batteries in which an electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet.

[0004] In addition, the electrode assembly installed in the battery housing is a power generation element that can be charged and discharged and has a stacked structure of a positive electrode, a separator and a negative electrode. The electrode assembly is classified into: a core roll type, which is wound with a separator inserted between the positive electrode and the negative electrode, and the positive electrode and the negative electrode are long sheets and coated with active materials; a stacked type, in which a plurality of positive electrodes and negative electrodes of predetermined sizes are sequentially stacked with a separator inserted therein; and a stacked / folded type, in which a stacked unit cell is wound with a long separation membrane. Among them, the core roll type electrode assembly is the easiest to manufacture and has the advantage of high energy density per unit weight.

[0005] Figure 1 is a view showing a state in which a core shaft is wound with a separator interposed in a winding process of a conventional core-wound type electrode assembly. Figure 2 It is a view mainly showing a separator in a conventional jelly-roll type electrode assembly in a state where a core shaft is separated after the conventional jelly-roll type electrode assembly is wound.

[0006] refer to Figure 1 , a core-wound type electrode assembly is manufactured by inserting a separator 1 between a positive electrode 2 and a negative electrode 3, and then winding them into a cylindrical shape, in which a positive electrode active material is applied to an aluminum foil and in which a negative electrode active material is applied to a copper foil, in which a negative electrode 3 is applied to a positive electrode 2. Specifically, the winding process is performed by first winding the separator 1 inserted between two parts of a mandrel 4 using a mandrel 4 divided into two parts, winding the positive electrode 2 and the negative electrode 3 together, and then removing the mandrel 4.

[0007] The electrode assembly 10 released by separating the mandrel 4 after winding into a cylindrical core-wound type has a hollow portion 11 formed in a central portion from which the mandrel 4 is removed. Figure 1 As shown, since the separator 1 is first wound around the mandrel 4 and then the positive electrode 2 and the negative electrode 3 are wound, the separator 1 is wound as shown in FIG. Figure 2 The shape shown is maintained in the hollow portion 11. The separator 1 is maintained in the center of the hollow portion 11 to partition the hollow portion 11. Since the separator 1 maintained in the hollow portion 11 of the electrode assembly 10 interferes with the insertion of the resistance welding rod in the subsequent assembly process, the separator 1 in the hollow portion 11 is organized by performing a reforming process after the winding process.

[0008] Figure 3 and Figure 4 is a view for describing a reforming process of a jellyroll type electrode assembly.

[0009] refer to Figure 3 and Figure 4 , the conventional reforming process is performed by inserting the heated reforming pin 20 into the hollow portion 11 of the electrode assembly 10 and pushing the separator 1 held in the hollow portion 11 toward the inner wall of the hollow portion 11. That is, the conventional reforming process is a method of inserting the reforming pin 20 to which heat is applied into the hollow portion 11 to shift the separator 1 held in the hollow portion 11 toward the inner wall of the hollow portion 11.

[0010] In particular, the specific process sequence includes: heating the reforming pin 20 (step 1); reforming by moving the reforming pin 20 forward and pushing the reforming pin 20 into the hollow portion 11 (step 2); and moving the reforming pin 20 backward (step 3).

[0011] However, when the outer diameter R_20 of the reforming pin 20 used in the conventional reforming process increases, the friction force with the diaphragm 1 may increase during the insertion or removal of the reforming pin 20, thereby causing damage to the diaphragm 1. Figure 4 As shown, in the conventional reforming process, when the reforming pin 20 is inserted into the hollow part 11, a gap d should be ensured between the reforming pin 20 and the inner wall of the hollow part 11. That is, reforming is performed in a state where the reforming pin 20 does not contact the inner wall of the hollow part 11.

[0012] Therefore, the process is performed in a non-contact state so that the heat of the reforming pin 20 is transferred and the diaphragm 1 held in the hollow portion 11 is shifted to the inner wall of the hollow portion 11 so as not to be lifted. However, in a non-contact manner, it is difficult for the held diaphragm 1 to be in full close contact with the inner wall of the hollow portion 11 so that the shape of the hollow portion 11 approaches a cylindrical shape. In the conventional non-contact reforming process, there are often cases where the process result is judged to be defective. Summary of the invention

[0013] Technical issues

[0014] The present disclosure aims to solve the problems of the prior art, and thus the present disclosure aims to provide a reforming process that can reduce the defects of the reforming process.

[0015] The present disclosure also relates to providing a reforming method that can reduce reforming process defects.

[0016] However, the problem to be solved by the present disclosure is not limited thereto, and a person of ordinary skill in the art will understand other unmentioned technical problems from the following description of the present disclosure.

[0017] Technical Solution

[0018] In one aspect of the present disclosure, a reformer includes a reformer pin unit and a rotating unit.

[0019] The reforming pin unit includes a reforming pin configured to be inserted into a hollow portion of an electrode assembly, and a driving unit configured to perform forward / backward and ascending / descending operations of the reforming pin.

[0020] The rotating unit is configured to rotate the electrode assembly about an axial direction of the hollow portion.

[0021] In the present disclosure, the outer diameter of the reformer pin is smaller than the inner diameter of the hollow portion.

[0022] Preferably, the electrode assembly is formed by winding a long sheet-like stack having a structure of a positive electrode, a separator and a negative electrode into a hollow portion at the center portion, the separator protruding from the inner wall of the hollow portion, wherein the reforming pin is inserted into the hollow portion while being spaced apart from the inner wall of the hollow portion.

[0023] The reforming pin is inserted into the hollow portion and then raised / lowered to fit the diaphragm to the inner wall of the hollow portion for reforming.

[0024] After the reforming is finished, the reforming pin is lowered / raised to move away from the inner wall of the hollow portion and then taken out of the hollow portion.

[0025] In one embodiment, the driving unit includes a first actuator connected to one side of the reformer pin for forward / backward operation, and a second actuator connected to the first actuator for raising / lowering operation.

[0026] Also, the rotating unit has a turntable structure that is rotated by a driving motor.

[0027] In another aspect of the present disclosure, a reforming method includes: heating a reforming pin; moving the reforming pin forward into a hollow portion of a jelly-roll type electrode assembly; raising / lowering the reforming pin in the hollow portion; rotating the electrode assembly with the reforming pin in the hollow portion; lowering / raising the reforming pin in the hollow portion; and moving the reforming pin backward from the hollow portion.

[0028] In another aspect of the present disclosure, a reforming method includes: inserting a reforming pin to which heat is applied into a hollow portion of an electrode assembly in a non-contact manner; moving the reforming pin to be in close contact with an inner wall of the hollow portion, and then rotating the electrode assembly around an axial direction of the hollow portion; and moving the reforming pin away from the inner wall of the hollow portion.

[0029] The reforming method may be performed using a reforming device according to the present disclosure.

[0030] Beneficial Effects

[0031] The present disclosure proposes a method in which a reforming pin to which heat is applied is inserted into a hollow portion of an electrode assembly; a diaphragm is pressed against a wall surface of the hollow portion by moving the reforming pin; and the diaphragm is then fixed by moving the electrode assembly. Therefore, according to the present disclosure, the conventional non-contact heating reforming method can be improved. According to the present disclosure, the reforming quality is improved.

[0032] The reformer of the present disclosure is capable of moving the reformer pin to move forward and backward, and is configured to raise / lower the reformer pin, rotate the electrode assembly, and lower / raise the reformer pin between the forward and backward movements of the reformer pin. In a reforming method using the reformer, the reformer pin can be inserted into the hollow portion of the electrode assembly without interference, and then the diaphragm can be pressed against the inner wall of the hollow portion. Since the electrode assembly rotates even when the reformer pin does not move in a state where the diaphragm is pressed against the inner wall of the hollow portion, reforming is performed in a contact manner along the inner diameter of the hollow portion. Then, the reformer pin can be removed from the hollow portion without interference.

[0033] According to the present disclosure, since the reforming pin does not contact the inner wall of the hollow portion of the electrode assembly when inserting and withdrawing the reforming pin, there is no defect such as damaging the separator or a portion of the separator pulled out from the electrode assembly.

[0034] When the present disclosure is applied, since reforming defects can be reduced and batch reforming can be performed, productivity of an electrode assembly can be improved.

[0035] According to the present disclosure, the shape of the hollow portion of the electrode assembly may be improved, and defects such as damage to the separator may be minimized.

[0036] Furthermore, since the reformer pin of the present disclosure can be implemented while maintaining the basic specifications of a conventional reformer pin, there is no need to design a separate reformer pin, and workability equal to or better than that of an existing reformer pin can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure; therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0038] Figure 1 is a view showing a state in which a core shaft is wound with a separator interposed in a winding process of a conventional core-wound type electrode assembly.

[0039] Figure 2 It is a view mainly showing a separator in a conventional jelly-roll type electrode assembly in a state where a core shaft is separated after the conventional jelly-roll type electrode assembly is wound.

[0040] Figure 3 and Figure 4 is a view for describing a reforming process of a jellyroll type electrode assembly.

[0041] Figure 5 is a schematic diagram showing a reformer according to an embodiment of the present disclosure.

[0042] Figure 6 1 is a view showing a stacking state of a jelly jelly type electrode assembly to be reformed before winding and a winding process in the present disclosure.

[0043] Figure 7 Shows Figure 6 The structure of the electrode plate is shown.

[0044] Figure 8 is a flowchart illustrating a reforming method according to an embodiment of the present disclosure.

[0045] Fig. 9 It shows that when Figure 8 The method is a diagram of states of an electrode assembly and a reforming pin at each step in a reforming device according to the present disclosure. DETAILED DESCRIPTION

[0046] Hereinafter, preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but are interpreted based on the principle that the inventor is allowed to appropriately define the terms for the best interpretation, based on the meanings and concepts corresponding to the technical aspects of the present disclosure. Therefore, the descriptions presented herein are only preferred embodiments for illustrative purposes and are not intended to limit the scope of the present disclosure, so it should be understood that other equivalents and modifications may be made thereto without departing from the scope of the present disclosure.

[0047] The same reference numerals indicate the same elements. In addition, in the drawings, in order to effectively explain the technical contents, the thickness, ratio and size of the elements are exaggerated.

[0048] Figure 5 is a schematic diagram showing a reformer according to an embodiment of the present disclosure.

[0049] The present disclosure proposes a method of inserting a reforming pin to which heat is applied into a hollow portion of an electrode assembly, pressing a separator to a wall surface of the hollow portion, and then fixing the separator. Figure 5 The reforming device is configured to perform the method.

[0050] refer to Figure 5 The reformer 200 includes a reforming pin unit 300 and a rotating unit 400. The reformer 200 is used to reform the electrode assembly A, which is a cylindrical core-wound type electrode assembly.

[0051] Figure 6 1 is a view showing a stacking state of a jelly jelly type electrode assembly to be reformed before winding and a winding process in the present disclosure. Figure 7 Shows Figure 6 The structure of the electrode plate is shown.

[0052] refer to Figure 6 The electrode assembly A may be manufactured by winding a stacked body formed by sequentially stacking the separator 112 , the positive electrode plate 110 , the separator 112 , and the negative electrode plate 111 at least once in one direction X.

[0053] In this case, if Figure 7 As shown, each of the positive electrode plate 110 and the negative electrode plate 111 may have a structure in which an active material layer 121 is formed on a current collector 120 having a long sheet shape, and a partial region of the current collector 120 may include an uncoated portion 122 where the active material layer 121 is not formed.

[0054] refer to Figure 7, each of the positive electrode plate 110 and the negative electrode plate 111 has a structure in which an active material layer 121 is coated on a sheet-shaped current collector 120 and includes an uncoated portion 122 in which the active material is not coated on one long side along the winding direction X. In the direction along the long side of the current collector 120 (X direction), one side becomes a core and the other side becomes a periphery.

[0055] like Figure 6 As shown, the electrode assembly A is manufactured by sequentially stacking the positive electrode plate 110 and the negative electrode plate 111 with two separators 112 and then winding them from a core in one direction X. In this case, the uncoated portions of the positive electrode plate 110 and the negative electrode plate 111 are opposite to each other in the direction of the short side of the current collector 120 (Y direction).

[0056] Similar to Figure 2 The hollow portion B of the hollow portion 11 shown is formed by using Figure 6 At the center portion (i.e., the inner core) of the electrode assembly A manufactured by the method of . After the winding process, the uncoated portion of the positive plate 110 and the uncoated portion of the negative plate 111 may be bent toward the core. Next, the current collector may be connected to the uncoated portion. Since the cross-sectional area of ​​the current collector is larger than the strip electrode connector, and the resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows, when a secondary battery is formed with the above structure, the cell resistance can be greatly reduced. When a positive plate 110 and a negative plate 111 each including an uncoated portion 122 are used without a separate electrode connector, a battery with a connector-free structure (wherein at least a portion of the uncoated portion 122 of each of the positive plate 110 and the negative plate 111 defines an electrode connector) may be implemented.

[0057] Keep as Figure 2 The diaphragm 112 of the shown shape may be formed in the hollow portion B. The present disclosure proposes a reforming process and a reforming apparatus 200 for forming the hollow portion B into a cylindrical shape by organizing the holding diaphragm 112 that divides the hollow portion B.

[0058] Return to reference Figure 5 The reforming pin unit 300 includes a reforming pin 310 that can be inserted into the hollow portion B of the electrode assembly A and a driving unit 320 configured to perform forward / backward and ascending / descending operations of the reforming pin 310 .

[0059] The driving unit 320 provides a driving force for the forward / backward and raising / lowering operation of the reforming pin 310. The driving unit 320 may include a motor or a cylinder operated by applied power and a signal, and when the driving unit 320 includes a motor, the driving unit 320 may further include a power transmission device (e.g., a bearing, a gear, a belt, or a chain) for transmitting the power of the motor to the reforming pin 310. More preferably, the driving unit 320 includes a cylinder that operates by applied power and a signal and can finely adjust its moving distance, and the end of a rod provided in the cylinder is detachably connected to the reforming pin 310.

[0060] For example, the driving unit 320 may include a first actuator 330 and a second actuator 340. The first actuator 330 and the second actuator 340 may include a hydraulic cylinder or a pneumatic cylinder. In another embodiment, the first actuator 330 and the second actuator 340 may be electrical components that move the rod forward and backward by using an electrical signal. In another embodiment, the first actuator 330 and the second actuator 340 may include a servo motor and a linear motion conversion mechanism. The linear motion conversion mechanism may be a rack / pinion that converts a rotary motion into a linear motion.

[0061] The first actuator 330 is connected to one side of the reforming pin 310 and performs forward / backward operation. The first actuator 330 may reciprocate. When the first actuator 330 operates, the reforming pin 310 may move forward and backward.

[0062] The second actuator 340 is connected to the first actuator 330 and performs a raising / lowering operation. The second actuator 340 may reciprocate. When the second actuator 340 operates, the first actuator 330 and the reforming pin 310 connected to the first actuator 330 may be raised / lowered.

[0063] Preferably, the first actuator 330 and the second actuator 340 include pneumatic cylinders capable of precise control using pneumatic pressure. When the driving unit 320 is an air device driven type unit, the driving unit 320 may further include an air compressor for supplying pneumatic pressure to the cylinders of the first actuator 330 and the second actuator 340, and the cylinders of the first actuator 330 and the second actuator 340 may be connected to the air compressor to maintain or release the pneumatic pressure. The cylinders may be operated by operating the pneumatic pressure, the supply of which is controlled by a control signal of a controller through a pneumatic pressure pipe, to perform forward / backward and raising / lowering operations of the reformer pin 310 connected to the end of the rod by moving the rod backward / forward.

[0064] A sensor for detecting the forward / backward and raised / lowered state of the reforming pin 310 may also be included in the reforming pin unit 300. The sensor may detect the forward / backward and raised / lowered state of the reforming pin 310 and may output a signal to the controller, and the controller may control the operation of the first actuator 330 and the second actuator 340 according to the input signal.

[0065] The rotating unit 400 is configured to rotate the electrode assembly A around the axial direction of the hollow portion B. When the electrode assembly A is rotated by means of the rotating unit 400, the center of the hollow portion B of the electrode assembly A is located at an appropriate position. The rotating unit 400 may have a structure of a turntable 420 that is rotated by means of a driving motor 410. When the electrode assembly A is mounted on the turntable 420 and the motor 410 is driven, the rotating unit 400 may rotate the electrode assembly A. In particular, in a state where the reforming pin 310 is located at an appropriate position in the hollow portion B, the electrode assembly A may be rotated in place. The rotating unit 400 may also include a fixture (not shown) so that the electrode assembly A is fixed to the turntable 420 and rotates when the turntable 420 rotates. For example, the motor 410 as a servo motor may be mounted on a base (not shown), and the turntable 420 may be connected to the shaft of the motor 410. By controlling the motor 410, the turntable 420 may change the rotation speed in various ways.

[0066] The rotating unit 400 may further include a sensor for detecting the installation state of the electrode assembly A and driving the motor 410. When it is detected that the reforming pin 310 contacts the inner wall of the hollow portion B, the reforming process may be stably performed by allowing the motor 410 to start operating.

[0067] The reforming pin unit 300 may further include a heating device 350 for heating the reforming pin 310 to a temperature at which reforming can be performed. The heating device 350 may include a power source and a heater in the reforming pin 310. Alternatively, the heating device 350 may include a heating element that heats the reforming pin 310 in thermal contact with the reforming pin 310.

[0068] The reforming pin 310 has a rod shape that is long in one direction. The reforming pin 310 has a straight central axis along its longitudinal direction and is not bent. The longitudinal cross section of the reforming pin 310 perpendicular to the longitudinal direction may be roughly circular. The center of the longitudinal cross section at any portion may be constant without shifting in the longitudinal direction. That is, the circumferential shape of the reforming pin 310 may be roughly circular, so that the hollow portion B of the electrode assembly A is cylindrical.

[0069] The front end of the reforming pin 310 may be formed in a sharp shape, and the remaining body of the reforming pin 310 connected to the front end may have a cylindrical shape. For example, the reforming pin 310 may have an inclined curved surface on the front end cross section in a cross section along the longitudinal direction. The shape of the front end of the reforming pin 310 may be different from the shape described and shown herein.

[0070] Moreover, the reforming pin 310 can be inserted into the hollow portion B of the electrode assembly A, and its insertion depth is equal to or greater than the length L_B of the hollow portion B of the electrode assembly A. Therefore, the cylindrical body of the reforming pin 310 can be positioned to extend from one end of the hollow portion B to the other end. The front end of the reforming pin 310 can be rounded to prevent the diaphragm 112 from being scratched when the reforming pin 310 is inserted into the hollow portion B of the electrode assembly A. In order to insert the reforming pin 310 into the hollow portion B of the electrode assembly A to a sufficiently large depth, a groove for accommodating the front end of the reforming pin 310 or a through hole for the front end of the reforming pin 310 to pass through can be formed in the turntable 420 of the rotating unit 400.

[0071] The outer diameter R_310 of the reforming pin 310 (specifically, the outer diameter of the body) is smaller than the inner diameter R_B of the hollow portion B of the electrode assembly A. The size of the outer diameter R_310 of the reforming pin 310 allows the reforming pin 310 to be inserted into the hollow portion B while being spaced apart from the inner wall of the hollow portion B. That is, the reforming pin 310 is inserted into the hollow portion B in a non-contact manner. The reforming pin 310 can be inserted to a position substantially the same as the center of the hollow portion B. Since the reforming pin 310 is inserted in a non-contact manner, the diaphragm 112 in the hollow portion B is not rolled up along the reforming pin 310 or is not pushed out of the hollow portion B.

[0072] The reforming pin 310 may be formed of a metal material to easily transfer heat, and may include a surface coating layer to reduce friction. The surface coating layer may be formed of, for example, but not limited to, a polyetheretherketone (PEEK) material. When the surface coating layer is formed of a PEEK material, the PEEK material is a thermoplastic resin with high strength, high rigidity, and excellent heat resistance, and thus the durability of the reforming pin 310 may be improved. Even when the retained diaphragm 112 protrudes in a Tai Chi pattern in the hollow portion B of the electrode assembly A, the reforming pin 310 may be inserted into the hollow portion B while minimizing the friction between the diaphragm 112 and the reforming pin 310.

[0073] The front end of the reforming pin 310 has a sharp shape for smooth insertion. Even when the retained diaphragm 112 protrudes in a Tai Chi pattern in the hollow portion B of the electrode assembly A, the front end having a sharp shape can be inserted into the empty space between the portions of the diaphragm 112 without contacting the diaphragm 112. When the reforming pin 310 moves forward and is inserted into the hollow portion B up to the cylindrical body, the reforming pin 310 may contact the protruding diaphragm 112, but can be inserted without difficulty by pushing the diaphragm 112 to the surrounding empty space.

[0074] The reforming pin 310 can be moved forward and inserted into the hollow portion B of the electrode assembly A, can contact the inner wall of the hollow portion by rising / lowering in the hollow portion B, and then the separator 112 held in the hollow portion B can be pressed against the inner wall of the hollow portion B for reforming. That is, the reforming step is performed using the reforming pin 310 in a contact manner.

[0075] The reforming pin 310 is not deformed during use but may contact the inner wall of the hollow portion B by the raising / lowering operation performed by the driving unit 320. As such, in the present disclosure, the reforming pin 310 contacts the inner wall of the hollow portion B by moving.

[0076] The reforming pin 310 does not contact the diaphragm 112 by expansion or bending. The reforming pin 310 contacts the diaphragm 112 by raising / lowering. Since the reforming pin 310 is not deformed, the consistency of the reforming process is excellent. Moreover, the reforming pin 310 of the present disclosure can be implemented while maintaining the basic specifications of the conventional reforming pin, so there is no need to design a separate reforming pin, and the machinability equal to or greater than the existing reforming pin can be ensured. In addition, there is no need to provide reforming pins of various sizes according to the inner diameter of the hollow portion B of the electrode assembly A. Since the reforming pin 310 is inserted into the hollow portion B and contacts the inner wall of the hollow portion B by raising / lowering, when the inner diameter of the hollow portion B changes, the contact area may change due to the difference in the radius of curvature with the reforming pin 310, but there is no need to replace the reforming pin 310 with a reforming pin of a different size.

[0077] The rotating unit 400 may rotate the electrode assembly A in a state where the reforming pin 310 contacts the inner wall of the hollow portion B. By at least one rotation, the entire inner wall of the hollow portion B of the electrode assembly A contacts the reforming pin 310. When the electrode assembly A rotates, the reforming pin 310 may be fixed in place. During the reforming process, the reforming pin 310 does not move and only the electrode assembly A moves. Since the electrode assembly A rotates even when the reforming pin 310 does not move, reforming may be performed in a contact manner along the inner diameter of the hollow portion B.

[0078] In the method of moving the reforming pin 310, since the trajectory of the reforming pin 310 is complex and changes over time, it is difficult to perform batch reforming. According to the present disclosure, since the reforming pin 310 does not move when contact reforming is performed, the trajectory does not change, and only the electrode assembly A rotates around the axial direction of the hollow portion B. In this rotation method, since the movement is always constant compared to the movement along the 3 axes, it is easy to manage the reforming process and is excellent in maintaining the reforming quality. Therefore, when the present disclosure is applied, since reforming defects can be reduced and batch reforming can be performed, the productivity of the electrode assembly can be improved. According to the present disclosure, the result of each reforming process can be constant, and it is not difficult to set the process quality.

[0079] Moreover, since the reforming device 200 of the present disclosure can reform in a contact manner, the conventional non-contact heating reforming process can be improved. Since the reforming pin 310 can contact the inner wall of the hollow portion B and directly contact the diaphragm 112 to transfer heat, heat can be uniformly transferred to all parts and reforming can be performed uniformly. According to the present disclosure, the reforming quality can be improved.

[0080] After the reforming process is finished, the reforming pin 310 may be lowered / raised, and then may be taken out of the hollow portion B. For example, the raised reforming pin 310 may be lowered to a position roughly matching the center of the hollow portion B (i.e., may return to its original position), and then may be taken out by moving backward. In contrast, the lowered reforming pin 310 may be raised to a position matching the center of the hollow portion B (i.e., may return to its original position), and then may be taken out by moving backward.

[0081] When the reforming device 200 is used, the separator 112 in the hollow portion B of the electrode assembly A may be prevented from being damaged due to poor insertion, reforming defects may be minimized, and reforming quality may be improved.

[0082] Figure 8 is a flowchart illustrating a reforming method according to an embodiment of the present disclosure.

[0083] refer to Figure 8 According to an embodiment of the present disclosure, the reforming method includes: a step S1 of heating the reforming pin; a step S2 of moving the reforming pin forward; a step S3 of raising / lowering the reforming pin; a step S4 of rotating the electrode assembly; a step S5 of lowering / raising the reforming pin; and a step S6 of moving the reforming pin backward.

[0084] With reference Figure 3Compared with the described existing process including heating the reforming pin (step 1), moving the reforming pin forward (step 2) and moving the reforming pin backward (step 3), the difference is that the reforming method according to the present disclosure includes step S3 of raising / lowering the reforming pin, step S4 of rotating the electrode assembly, and step S5 of lowering / raising the reforming pin between step S2 of moving the reforming pin forward and step S6 of moving the reforming pin backward.

[0085] A reforming method may be performed using the reformer 200 according to the present disclosure.

[0086] Fig. 9 It shows that when Figure 8 The method is a view of the state of the electrode assembly and the reforming pin at each step in the reforming device according to the present disclosure. Fig. 9 , the relative position of the reforming pin 310 as seen from the side surface of the electrode assembly A and the relative position of the reforming pin 310 as seen from the end of the electrode assembly A are simultaneously shown at each step during the reforming process. In some drawings, some reference numerals are omitted.

[0087] Will refer to Figure 8 and 9 The reforming method of the present disclosure is described.

[0088] First, if Fig. 9 As shown in (a) of FIG. 4 , the electrode assembly A is mounted on the turntable 420 of the rotating unit 400 to be in a ready state. Next, the reforming pin 310 is heated (step S1 ).

[0089] Next, if Fig. 9 As shown in (b), the reforming pin 310 is moved forward into the hollow portion B of the electrode assembly A (step S2). In this case, this can be achieved by driving the first actuator 330 of the driving unit 320. The reforming pin 310 can be inserted into the center of the hollow portion B.

[0090] As described above, the outer diameter R_310 of the reforming pin 310 is smaller than the inner diameter R_B of the hollow portion B of the electrode assembly A. Moreover, even when the diaphragm 112 having the Tai Chi pattern is formed on the inner wall of the hollow portion B, the reforming pin 310 can be moved forward and can be inserted into the hollow portion B while being spaced apart from the inner wall of the hollow portion B without causing significant strain on the diaphragm 112. Therefore, due to the reforming pin 310 in the step S2 of moving the reforming pin forward, the diaphragm 112 does not protrude in the opposite direction. Since friction with the diaphragm 112 does not occur when the reforming pin 310 is inserted, there is no need to worry about the diaphragm 112 being damaged or torn.

[0091] Next, the reforming pin 310 may cling the diaphragm 112 held in the central portion of the hollow portion B to the inner wall of the hollow portion B in step S3 of raising / lowering the reforming pin. Fig. 9 (c) shows an embodiment in which the reforming pin 310 is elevated in the hollow portion B. Therefore, unlike conventional reforming performed in a non-contact state, reforming according to the present disclosure can be performed in a contact state.

[0092] Since the cylindrical body of the reforming pin 310 is located in the hollow portion B and the reforming pin 310 extends along the length direction of the hollow portion B without bending, the reforming pin 310 can uniformly contact the wall surface of the hollow portion B in the longitudinal direction without any part being out of contact.

[0093] Next, step S4 of rotating the electrode assembly A is performed in a state where the reforming pin 310 is located in the hollow portion B. Fig. 9 (d) shows an example in which the electrode assembly A rotates clockwise. The electrode assembly A may be rotated by driving the motor 410 of the rotating unit 400 .

[0094] Since the reforming pin 310 uniformly sticks the diaphragm 112 to the wall surface of the hollow portion B in the longitudinal direction of the hollow portion B without any part not contacting the diaphragm 112 in step S3, and the electrode assembly A is rotated in place in step S4, the diaphragm 112 can be collectively reformed along the inner wall of the hollow portion B. The reforming pin 310 can uniformly press the diaphragm 112 over the entire circumference of the inner wall of the hollow portion B. The diaphragm 112 is thermally deformed and displaced toward the inner wall of the hollow portion B. Therefore, due to the Figure 2 The Tai Chi pattern shown in can be completely attached to the inner wall of the hollow portion B, so the shape of the hollow portion B can be close to a cylindrical shape. In addition, due to the rotation of the electrode assembly A, the diaphragm 112 on the inner wall of the hollow portion B can not be forced to bend and fold, but can be rolled into a curved shape and neatly rolled around the inner wall. Therefore, according to the present disclosure, process defects can be reduced. Since reforming can be achieved using at least one rotation, it is expected that the process time can be reduced.

[0095] Since the Tai Chi pattern is fully formed through the reforming process and the Tai Chi pattern is not maintained in the hollow portion B, the insertion of the resistance welding rod can be performed in the subsequent process without interference, and defects during the insertion of the center pin can be avoided. Therefore, since the resistance welding rod or the center pin can be smoothly inserted into the hollow portion B of the electrode assembly A during the assembly process, and secondary defects caused by the poor shape of the hollow portion B can be minimized, the production process yield of the secondary battery can be improved.

[0096] The reforming pin 310 may be fixed while the electrode assembly A is rotated. Therefore, the trajectory of the reforming pin 310 is not complicated, and there is no need to control the complicated trajectory of the reforming pin 310 .

[0097] Next, when the step S5 of lowering / raising the reforming pin is performed, the reforming pin 310 moves away from the inner wall of the hollow portion B of the electrode assembly A. Fig. 9 (e) shows an embodiment in which the reforming pin 310 is lowered in the hollow portion B.

[0098] Next, if Fig. 9 As shown in (f), step S6 of moving the reforming pin backward is performed. Since the outer diameter R_310 of the reforming pin 310 is smaller than the inner diameter R_B of the hollow portion B of the electrode assembly A, the process can be ended by removing the reforming pin 310 from the hollow portion B without interference between the reforming pin 310 and the hollow portion B. When removing the reforming pin 310, there is no friction with the diaphragm 112, so there is no need to worry about the diaphragm 112 being damaged or torn. In the hollow portion B of the electrode assembly A that has been reformed, even when the diaphragm 112 protrudes and separates the hollow portion B before reforming, the diaphragm 112 can be completely attached to the inner wall of the hollow portion B due to the reforming, and a hollow portion B having a cylindrical shape can be formed without damaging the electrode assembly A (e.g., tailing off).

[0099] Compared with the existing reformer device (such as reference 2) in which the reformer pin 20 can only move forward and backward Figure 3 Compared with the above, the reformer 200 according to the present disclosure adds the raising / lowering operation of the reformer pin 310. The reformer 200 according to the present disclosure includes a rotating unit 400, which is not provided in the existing reformer.

[0100] In summary, the reforming method of the present disclosure may include: the steps of heating the reforming pin; moving the reforming pin forward; raising the reforming pin; rotating the electrode assembly; lowering the reforming pin; and moving the reforming pin backward. The method may be modified to be carried out in a method including: heating the reforming pin; moving the reforming pin forward; lowering the reforming pin; rotating the electrode assembly; raising the reforming pin; and moving the reforming pin backward.

[0101] In addition, another reforming method disclosed in the present invention may include the following steps: inserting the reforming pin 310 to which heat is applied into the hollow portion B of the electrode assembly A in a non-contact manner; the step of pressing the reforming pin 310 against the inner wall of the hollow portion B by moving the reforming pin 310 and then rotating the electrode assembly A relative to the reforming pin 310; the step of moving the reforming pin 310 away from the inner wall of the hollow portion B, and this method may also be performed by the reforming device 200.

[0102] Therefore, the present disclosure proposes a method in which a reforming pin 310 to which heat is applied is inserted into the hollow portion B of the electrode assembly A; the diaphragm 112 is pressed against the wall surface of the hollow portion B by moving (raising / lowering) the reforming pin 310; and the diaphragm 112 is then fixed by moving (rotating) the electrode assembly A.

[0103] According to the present disclosure, the contact between the reforming pin 310 and the inner wall of the hollow portion B can be made only under the condition of raising / lowering the reforming pin 310, without deforming the reforming pin 310, changing the shape of the reforming pin 310, and increasing the outer diameter of the reforming pin 310. Since the controllable contact is made only by mechanical movement, the process management is easy and predictable, and since only the raising / lowering operation needs to be added to the existing forward / backward operation, the reforming device 200 can be simply implemented and the process quality can be significantly improved. In addition, reforming can be performed in a state where the reforming pin 310 uniformly contacts the entire inner wall of the hollow portion B by rotating the electrode assembly A.

[0104] The reformer 200 and reforming method according to the present disclosure may be particularly usefully applied to a process for manufacturing a small cylindrical secondary battery having a form factor of 18650 or 21700. In addition, the reformer 200 and reforming method according to the present disclosure may also be applied to reforming an electrode assembly for manufacturing a cylindrical secondary battery having an increased form factor. The cylindrical secondary battery having an increased form factor may be implemented as described in reference Figure 6 and Figure 7 A jointless cylindrical secondary battery is described. The increased form factor results in increased energy density, increased safety against thermal runaway, and improved cooling efficiency.

[0105] Preferably, the reforming device 200 and the reforming method according to the present disclosure can be used in the reforming process of the electrode assembly of a cylindrical secondary battery having a shape factor ratio (the value obtained by dividing the diameter of the cylindrical secondary battery by the height, i.e., the ratio of the diameter Φ to the height H) greater than about 0.4. Such a secondary battery is suitable for use as a high-output, high-capacity secondary battery for HEV. Such a secondary battery may be, for example, a 46110 battery cell, a 48750 battery cell, a 48110 battery cell, a 48800 battery cell, or a 46800 battery cell. When the electrode assembly A is such an electrode assembly, the length L_B of the hollow portion B may be 65 mm or more, and the inner diameter R_B of the hollow portion B may be 2 mm to 8 mm. Considering that the length L_B and the inner diameter R_B of the hollow portion B may vary according to the shape factor of the secondary battery, the reforming pin 310 included in the reforming device 200 of the present disclosure may have a length L_310 and an outer diameter R_310 so as to be inserted into the hollow portion B without interference.

[0106] Although one or more embodiments of the present disclosure have been described with reference to the embodiments and the accompanying drawings, the present disclosure is not limited thereto, and persons skilled in the art will understand that various changes in form and details may be made therein without departing from the scope of the present disclosure as defined by the appended claims.

[0107] One of ordinary skill in the art will understand that when terms indicating directions such as up, down, front, and back are used, these terms are merely for ease of explanation and may change depending on the location of the target object, the location of the observer, and the like.

[0108] [reference numerals]

[0109] 200: Reformer 300: Reformer pin unit

[0110] 310: Realignment pin 320: Driving unit

[0111] 330: first actuator 340: second actuator

[0112] 350: Heating device 400: Rotating unit

[0113] 410: Motor 420: Turntable

Claims

1. A reforming device, comprising: a reforming pin unit including a reforming pin configured to be inserted into a hollow portion of an electrode assembly and a driving unit configured to perform forward / backward operation and raising / lowering operation of the reforming pin; as well as A rotating unit is configured to rotate the electrode assembly around an axial direction of the hollow portion.

2. The reformer according to claim 1, wherein: The outer diameter of the reformer pin is smaller than the inner diameter of the hollow portion.

3. The reformer according to claim 1, wherein: The electrode assembly is formed by winding a long sheet-shaped stack having a structure of a positive electrode, a separator, and a negative electrode to have the hollow portion at a center portion, the separator protruding from an inner wall of the hollow portion, wherein the reforming pin is inserted into the hollow portion while being spaced apart from the inner wall of the hollow portion.

4. The reformer according to claim 3, wherein: The reforming pin is inserted into the hollow portion and then raised / lowered to fit the diaphragm to the inner wall of the hollow portion for reforming.

5. The reformer according to claim 4, wherein: After the reforming is finished, the reforming pin is lowered / raised to move away from the inner wall of the hollow portion, and then the reforming pin is taken out of the hollow portion.

6. The reformer according to claim 1, wherein: The driving unit comprises: a first actuator connected to one side of the reformer pin to perform the forward / backward operation; and A second actuator connected to the first actuator to perform the raising / lowering operation.

7. The reformer according to claim 1, wherein: The rotating unit has a turntable structure that is rotated by a driving motor.

8. A reforming method, comprising the following steps: Heating the reforming pin; moving the reforming pin forward into the hollow portion of the jelly-roll type electrode assembly; raising / lowering the reformer pin in the hollow portion; rotating the electrode assembly in a state where the reforming pin is located in the hollow portion; lowering / raising the reformer pin in the hollow portion; as well as The reformer pin is moved rearwardly from the hollow portion.

9. A reforming method, comprising: inserting a reforming pin to which heat is applied into a hollow portion of the electrode assembly in a non-contact manner; moving the reforming pin to be closely attached to the inner wall of the hollow portion, and then rotating the electrode assembly around the axial direction of the hollow portion; and The reformer pin is moved away from the inner wall of the hollow portion.

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