Winding roller structure and winding method of winding electrode assembly

Abstract

A winding roller structure and a winding method of winding an electrode assembly are disclosed. The winding roller structure configured to achieve edge bending of an electrode assembly and wind the electrode assembly including first and second electrode plates and a separator disposed therebetween includes: an edge bending unit configured to bend both side edges in a longitudinal direction of the electrode assembly in one direction; and a winding unit configured to wind the electrode assembly that has passed through the edge bending unit, in which the edge bending unit includes a nip roller and an anvil roller each extending in a longitudinal direction and arranged in parallel, the nip roller including a roller body and a pair of expanded diameter portions, and a pair of expanded-diameter portions provided at both ends of the roller body and having a diameter larger than that of the roller body, the anvil roller being disposed adjacent to the nip roller between the pair of expanded-diameter portions, and both side edges in a longitudinal direction of the electrode assembly being bent in one direction when the electrode assembly passes between the nip roller and the anvil roller.

Description

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0163983 filed in the Korean Intellectual Property Office on November 23, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to a winding roller structure for realizing edge bending of an electrode assembly and a winding method using the same. More specifically, the present disclosure relates to a winding roller structure and a winding method using the same, the winding roller structure operating to bend and pre-compress a first electrode uncoated portion and a second electrode uncoated portion of an electrode assembly in one direction and then winding during a winding process for accommodating the electrode assembly in a cylindrical case. Background Art

[0003] Generally, a cylindrical secondary battery may include a case, an electrode assembly accommodated in the case, a terminal coupled to a terminal hole provided at one end of the case, and a cap plate sealing an opening at the other end of the case.

[0004] Specifically, the electrode assembly is wound into a circular shape when passing through the winding roller structure to form a pole core to be accommodated in a cylindrical shell, and the base material protruding from the upper and lower parts of the pole core is electrically connected to the cap assembly by welding the base material to the cap assembly. Generally, the electrode assembly includes a first electrode plate (positive electrode plate), a second electrode plate (negative electrode plate) and a separator, wherein the positive electrode active material is formed on both side surfaces of the first electrode plate as the positive electrode plate, the negative electrode active material is formed on both side surfaces of the second electrode plate as the negative electrode plate, and the uncoated portion (the first electrode uncoated portion and the second electrode uncoated portion) where the active material is not applied is formed in a portion of the first electrode plate and a portion of the second electrode plate, respectively. The above-mentioned base material refers to the uncoated portion of the electrode plate where the active material is not applied.

[0005] In the case of cylindrical secondary batteries, the coating area of ​​the active material decreases as the proportion of the matrix material in the electrode plate increases, which leads to a capacity loss of the battery. Attempts have been made to reduce the area of ​​the matrix material to achieve high capacity, but as the interval between the matrix materials increases, the problem of reduced heat capacity of the welding area occurs. Accordingly, research and development of methods that can increase battery capacity by effectively reducing the protrusion length of the matrix material is required.

[0006] The above information disclosed in the background of the present invention is only for enhancing understanding of the background of the present disclosure and accordingly may include information that does not constitute related art. Summary of the invention

[0007] The present disclosure is directed to providing a winding roller structure and a winding method which provide a secondary battery capable of reducing a protruding length of a base material required for welding to achieve an increase in battery capacity.

[0008] A winding roller structure is configured to achieve edge bending of an electrode assembly according to an embodiment of the present disclosure and to wind the electrode assembly including a first electrode plate and a second electrode plate and a separator disposed therebetween. The winding roller structure includes an edge bending unit configured to bend two side edges on opposite sides of the electrode assembly in the longitudinal direction of the electrode assembly. The edge bending unit includes a clamping roller and an anvil roller each extending in the longitudinal direction of the edge bending unit and arranged parallel to each other. The clamping roller includes a roller body and an expanded diameter portion, each of the expanded diameter portions having a diameter larger than the diameter of the roller body. The anvil roller is disposed adjacent to the clamping roller between the expanded diameter portions. The winding roller structure also includes a winding unit configured to wind the electrode assembly that has passed through the edge bending unit. The edge bending unit is configured so that, when the electrode assembly passes between the clamping roller and the anvil roller, the two side edges in the longitudinal direction of the electrode assembly are bent in one direction.

[0009] In addition, the enlarged diameter portions of the clamping roller each include an inclined portion that is inclined at a predetermined angle relative to the roller body and connected to the roller body, and the edge bending unit is configured such that, when the electrode assembly enters the edge bending unit, the two side edges of the electrode assembly can be squeezed by the inclined portion and bent in the one direction.

[0010] Further, the edge bending unit is configured to bend the two side edges of the electrode assembly in the same direction.

[0011] According to one embodiment of the present disclosure, there is also provided a winding method for achieving edge bending of an electrode assembly, the electrode assembly comprising a first electrode plate and a second electrode plate and a separator disposed between the first electrode plate and the second electrode plate. The winding method comprises: preparing an electrode assembly by stacking the first electrode plate and the second electrode plate on each other with the separator between them so that the first electrode uncoated portion of the first electrode plate is exposed at a first end in a longitudinal direction and the second electrode uncoated portion of the second electrode plate is exposed at a second end in the longitudinal direction; passing the electrode assembly through the edge bending unit of the above-mentioned winding roller structure, and the two side edges in the longitudinal direction of the electrode assembly are bent to form a bent edge portion; and passing the electrode assembly having the bent edge portion through the winding unit of the winding roller structure to wind the electrode assembly.

[0012] Further, the two side edges are bent in a direction toward a winding axis of the electrode assembly.

[0013] Furthermore, in the forming of the bent edge portion, when the electrode assembly passes through the gap provided between the nip roller and the anvil roller, the two side edges are pressed and bent by the enlarged diameter portion of the nip roller.

[0014] In addition, the two side edges may be the first electrode uncoated portion and the second electrode uncoated portion, respectively, and the first electrode uncoated portion and the second electrode uncoated portion may be pressed by an inclined portion provided in the expanded diameter portion of the nip roller and may be bent at a predetermined angle.

[0015] Furthermore, the two side edges of the electrode assembly are bent in the same direction, wherein: when the electrode assembly passes through a gap provided between the clamping roller and the anvil roller, the first electrode uncoated portion and the second electrode uncoated portion are bent in one direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a perspective view illustrating a cylindrical secondary battery according to one embodiment of the present disclosure.

[0017] Figure 2 is based on Figure 1 Cross-sectional view of a cylindrical secondary battery.

[0018] Figure 3 Including formation Figure 2 Plan view and cross-sectional view of the electrode assembly of the pole core.

[0019] Figure 4 is a cross-sectional view of an exemplary electrode assembly, wherein Figure 3 The electrode assembly in the embodiment of the present invention is pre-compressed to achieve edge bending.

[0020] Figure 5 is a conceptual diagram schematically illustrating a winding roller structure for implementing edge bending of an electrode assembly according to one embodiment of the present disclosure.

[0021] Figure 6 This is an example configuration Figure 5 Diagram of the edge bending unit in the winding roller structure.

[0022] Figure 7 It is a cross-sectional view of a state where an electrode assembly is wound to achieve edge bending.

[0023] Fig. 8A and Figure 8B is a conceptual diagram exemplarily illustrating an edge bending unit of a winding roller structure according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments of the present disclosure are provided to more completely describe the present disclosure to those skilled in the art, and the following embodiments may be modified into various other forms, and the scope of the present disclosure is not limited to the following embodiments. On the contrary, these embodiments are provided to make the present disclosure more truthful and complete, and to fully convey the spirit of the present disclosure to those skilled in the art.

[0025] Further, in the following figures, for the convenience and clarity of description, the size (e.g., thickness) of each layer is enlarged, and the same reference numerals in the figures indicate the same elements. As used in this specification, the term "and / or" includes any one and all combinations of one or more of the listed items. Further, the meaning of "connection" in this specification refers not only to the situation that component A and component B are directly connected, but also to the situation that component C is between component A and component B to indirectly connect component A and component B. The terms used in this specification are used to describe specific embodiments and are not intended to limit the present disclosure. As used in this specification, unless the context clearly indicates otherwise, the singular form may also include the plural form. Further, when used in this specification, "include" and / or "comprising" specify the existence of the mentioned features, quantity, step, operation, component, element and / or its group, and do not exclude the existence or addition of one or more other features, quantity, step, operation, component, element and / or its group.

[0026] Although the terms "first", "second", etc. are used in this specification to describe various components, parts, regions, layers and / or parts, it is obvious that these components, parts, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one component, component, region, layer or part from another component, component, region, layer or part. Accordingly, without departing from the teachings of the present disclosure, a first component, component, region, layer or part to be described later may refer to a second component, component, region, layer or part.

[0027] Spatial related terms such as "below", "below", "below", "above", and "on" are used to easily understand the relationship between one element or feature shown in the figure and another element or feature. These spatial related terms are provided to easily understand the present disclosure according to various process states or use states of the present disclosure, and are not intended to limit the present disclosure. For example, when the elements or features in the figure are reversed, the elements or characteristics described as "below" or "below" become "above" or "above". Accordingly, "below" is a concept that includes "above" and "below".

[0028] Cylindrical secondary battery 100

[0029] First, a cylindrical secondary battery 100 manufactured by the present disclosure will be described in detail with reference to the accompanying drawings.

[0030] Figure 1 is a perspective view illustrating a cylindrical secondary battery according to one embodiment of the present disclosure, and Figure 2 is based on Figure 1 Cross-sectional view of a cylindrical secondary battery.

[0031] like Figure 1 and Figure 2 As shown, a cylindrical secondary battery 100 according to the present disclosure may include a case 110, an electrode assembly 130 accommodated in the case 110, a terminal 150 coupled to a terminal hole provided at one end of the case 110, and a cap plate 160 sealing an opening at the other end of the case 110.

[0032] The housing 110 may include a circular upper surface portion 111 and a side surface portion 112 extending downwardly from an edge of the upper surface portion 111 by a certain length, and may further include a curved portion 111a curved in an arc shape between the upper surface portion 111 and the side surface portion 112. The upper surface portion 111 may have a flat circular plate shape, and the central portion 113 may be positioned at the center of the upper surface portion 111. Since the central portion 113 is positioned farther from the side surface portion 112 of the housing 110 than the upper surface portion 111, a step may be provided between the central portion 113 and the upper surface portion 111. The central portion 113 may have a terminal hole 113a passing therethrough.

[0033] The terminal 150 may be inserted into the terminal hole 113a of the case 110 to be electrically connected to the first collector plate 121 to be described below. The terminal 150 may be electrically connected to the first electrode plate 132 of the electrode assembly 130 through the first collector plate 121. That is, the terminal 150 may be a positive terminal. The terminal 150 and the case 110 may have different polarities.

[0034] Meanwhile, the lower end portion of the housing 110 is open, and the electrode assembly 130 may be inserted through the open lower end portion of the housing 110 together with the electrolyte. In this case, the electrolyte and the electrode assembly 130 may be inserted into the housing 110 in a state where the open lower end portion faces upward. After the electrolyte and the electrode assembly 130 are inserted, the cap plate 160 may be coupled to the open lower end portion to seal the interior of the housing 110. Here, the electrolyte is used to allow lithium ions to move between the first electrode plate 132 and the second electrode plate 134 constituting the electrode assembly 130. After the electrode assembly 130 is inserted into the housing 110 through the open lower end portion, a bent portion may be formed to prevent the electrode assembly 130 from being separated from the housing 110.

[0035] The cap plate 160 may be a circular metal plate and is coupled to the lower end portion of the housing 110. The lower surface of the cap plate 160 may be exposed to the outside. The cap plate 160 may be coupled to the lower end portion of the housing 110 with a gasket interposed therebetween to prevent electrical connection with the housing 110. The cap plate 160 is not electrically connected to the positive electrode or the negative electrode of the electrode assembly 130 and therefore may not have a separate electrical polarity.

[0036] Next, Figure 3 Shows the formation of the winding before Figure 2 The plan view and cross-sectional view of the electrode assembly of the pole core in FIG. Figure 3 As shown, the electrode assembly 130 includes a first electrode plate 132 , a second electrode plate 134 and a separator 137 .

[0037] The first electrode plate 132 may be a plate having a positive electrode active material layer 132c (eg, a transition metal oxide (LiCoO 2 、LiNiO 2 、LiMn 2 O 4 The first electrode plate 132 may be a positive electrode plate of a first electrode plate 132 having a first electrode uncoated portion 132a to which the positive electrode active material layer 132c is not applied. The second electrode plate 134 may be a negative electrode plate on which a negative electrode active material layer 134c (e.g., graphite, carbon, etc.) is formed on both surfaces of the plate. The second electrode uncoated portion 134a to which the negative electrode active material layer 134c is not applied may be formed in a portion of the second electrode plate 134. The separator 137 may be interposed between the first electrode plate 132 and the second electrode plate 134 to prevent a short circuit and allow only lithium ions to move. The first electrode plate 132 may be a copper (Cu) foil or a nickel (Ni) foil, the second electrode plate 134 may be an aluminum (Al) foil, and the separator 137 may be a polyethylene (PE) film or a polypropylene (PP) film, but the present disclosure is not limited to these materials. In this case, the first electrode plate 132 and the second electrode plate 134 may be arranged so that the first electrode uncoated portion 132a and the second electrode uncoated portion 134a, which are not coated with an active material for winding, are in opposite directions. For example, the first electrode plate 132, which is a positive electrode plate, may be arranged so that the first electrode uncoated portion 132a is based on Figure 3 The second electrode plate 134, which is a negative electrode plate, may be arranged so that the second electrode uncoated portion 134a is based on Figure 3 Face upward.

[0038] After stacking the first electrode plate 132, the second electrode plate 134 and the separator 137, the electrode assembly 130 is wound into a substantially cylindrical shape from the front of the winding. In the electrode assembly 130, the positive electrode uncoated portion not coated with the positive electrode active material may protrude in the upward direction from the first electrode plate 132, and the negative electrode uncoated portion not coated with the negative electrode active material may protrude in the downward direction from the second electrode plate 134. Further, in the electrode assembly 130, the outermost positive electrode uncoated portion may not protrude in the upward direction, and the outermost negative electrode uncoated portion may not protrude in the downward direction. That is, the electrode assembly 130 may include a concave step at the upper outermost and lower outermost compared to other regions.

[0039] The cylindrical secondary battery 100 according to the present disclosure includes a first current collector plate 121 and a second current collector plate 122. Figure 2 As shown, the first collector plate 121 may be a circular metal plate having a shape corresponding to the upper surface of the electrode assembly 130, and may be made of aluminum (Al). The first collector plate 121 may be fixed and electrically connected to the first electrode plate 132 exposed at the upper portion of the electrode assembly 130 by welding in a state where its lower surface is in contact with the upper surface of the electrode assembly 130. The first collector plate 121 may be fixed and electrically connected to the terminal 150 by welding in a state where its upper surface is in contact with the lower surface of the terminal 150. The first collector plate 121 becomes a current flow path between the first electrode plate 132 of the electrode assembly 130 and the terminal 150. The first collector plate 121 may be welded to the electrode assembly 130 and accommodated in the housing 110, and then welded to the terminal 150.

[0040] The second current collector plate 122 may include a circular flat portion corresponding to the lower surface of the electrode assembly 130 and an extension portion extending in a downward direction from the edge of the flat portion. The upper surface of the flat portion may be in contact with the lower surface of the electrode assembly 130. In this state, the upper surface of the flat portion may be fixed and electrically connected to the second electrode plate 134 exposed at the lower portion of the electrode assembly 130 by welding.

[0041] According to the present disclosure, before winding the electrode assembly 130, a process (hereinafter referred to as edge bending) of folding both side edges (i.e., the first electrode uncoated portion 132a and the second electrode uncoated portion 134a) in the longitudinal direction of the electrode assembly 130 in an inward direction (i.e., a direction toward the winding axis) is performed. After bending is performed at both side edges of the electrode assembly 130, a winding process is performed, and after winding, as the electrode assembly 130 is pressed in the longitudinal direction, a Figure 1 Since the edge bending is performed before the electrode assembly 130 is wound, as shown in FIG. Figure 7As shown, in the wound electrode assembly 130, the matrix material (the first electrode uncoated portion 132a and the second electrode uncoated portion 134a) protruding in the longitudinal direction is folded in the radially inward direction around the winding axis. In this state, as the electrode assembly 130 is pressed in the longitudinal direction, the protruding matrix material is in the form of covering both ends of the pole core in the longitudinal direction. The edge bending and winding process will be described in detail below.

[0042] Figure 4 is a cross-sectional view of an exemplary electrode assembly, wherein Figure 3 The electrode assembly in the embodiment is pre-compressed to achieve edge bending. Figure 4 As shown, the electrode assembly 130 provided according to one embodiment of the present disclosure may include curved edge portions 132b, 134b formed by folding or bending a portion of the first electrode uncoated portion 132a of the first electrode plate 132 and a portion of the second electrode uncoated portion 134a of the second electrode plate 134. That is, as shown in FIG. Figure 4 As shown, in the first electrode plate 132 and the second electrode plate 134, the curved edge portions 132b, 134b can be formed by bending or folding the first electrode uncoated portion 132a and the second electrode uncoated portion 134a. These curved edge portions 132b, 134b can be formed by a process of passing between the nip roller 1110 and the anvil roller 1130 of the edge bending unit 1100 constituting the winding roll structure 1000 in the manufacturing process, which will be described in detail below.

[0043] After forming the bent edge portions 132b, 134b at both side edges in the longitudinal direction of the electrode assembly 130, the electrode assembly 130 is wound to form a core. Since the electrode assembly 130 is wound in a state where the bent edge portions 132b, 134b are formed in the first electrode uncoated portion 132a and the second electrode uncoated portion 134a, as shown in FIG. Figure 7 As shown, the curved edge portions 132b, 134b are in an angled state in a direction close to the winding axis. Figure 7 The first electrode plate 132 and the second electrode plate 134 are illustrated in an enlarged manner, so the interval between the folded curved edge portions 132b, 134b is enlarged. In practice, the electrode uncoated portions formed with the curved edge portions 132b, 134b can be kept at a certain distance so that there is a partial overlap between adjacent electrode uncoated portions. The interval between the uncoated portions can be changed according to the electrode plate design of the electrode assembly 130.

[0044] Thereafter, the bent edge portions 132b, 134b may be pressed by the first and second collector plates 121, 122, and the first and second collector plates 121, 122 may be connected to these bent edge portions 132b, 134b, respectively. Accordingly, the terminal 150 and the case 110 may be electrically connected to the electrode assembly 130.

[0045] In this way, when the bent edge portions 132b, 134b are preformed by folding the electrode uncoated portions before winding, since the matrix material can overlap consistently and coherently when welding the current collector plates 121, 122, there is an effect of increasing the amount of overlap. When the pre-pressing process is not applied, there is a problem that the end portion of the matrix material is irregularly squeezed and bent, and therefore, the height of the end portion or the amount of overlap of the end portion of the matrix material becomes irregular. However, when the pre-pressing process is applied, since the matrix material is bent in the same direction, the end portion of the matrix material overlaps consistently, and therefore, the amount of overlap of the end portion of the matrix material increases compared to the case where the pre-pressing process is not applied. Further, as the matrix material is bent consistently, the height of the end portion of the matrix material is aligned consistently, and therefore, the amount of the matrix material to be welded when welding the current collector plates 121, 122 increases, thereby improving the tensile strength. Accordingly, due to the consistent alignment of the matrix material, there is an effect of improving the resistance distribution and improving the welding quality.

[0046] Winding roller structure 1000 for realizing edge bending of electrode assembly

[0047] Figure 5 is a conceptual diagram schematically illustrating a winding roller structure for implementing edge bending of an electrode assembly according to an embodiment of the present disclosure, and Figure 6 This is an example configuration Figure 5 FIG. 1 is a diagram of an edge bending unit of a winding roller structure in FIG. Hereinafter, a winding roller structure 1000 for implementing edge bending of an electrode assembly according to an embodiment of the present disclosure will be described.

[0048] The winding roll structure 1000 of the present disclosure is a device for forming a pole core by winding an electrode assembly 130 including a first electrode plate 132 and a second electrode plate 134 with a separator 137 disposed therebetween. The electrode assembly 130 in which the first electrode plate 132, the second electrode plate 134 and the separator 137 overlap in the longitudinal direction enters the winding roll structure 1000 in the width direction of the winding roll structure 1000. After the edge bending and winding processes are sequentially performed in the winding roll structure 1000, the pole core is formed and discharged from the winding roll structure 1000.

[0049] The winding roll structure 1000 of the present disclosure includes an edge bending unit 1100 that bends both side edges in the longitudinal direction of the electrode assembly 130 in one direction (ie, the same direction) and a winding unit 1700 that winds the electrode assembly 130 that has passed through the edge bending unit 1100 .

[0050] The edge bending unit 1100 includes a nip roller 1110 and an anvil roller 1130 extending in the longitudinal direction and arranged in parallel. When the electrode assembly 130 enters the winding roll structure 1000 of the present disclosure, the electrode assembly 130 first passes between the nip roller 1110 and the anvil roller 1130 constituting the edge bending unit 1100. In this process, in the electrode assembly 130, a portion of the first electrode uncoated portion 132a of the first electrode plate 132 and a portion of the second electrode uncoated portion 134a of the second electrode plate 134 are folded or bent to form curved edge portions 132b, 134b. Hereinafter, the process of forming the curved edge portions 132b, 134b before winding is described as an edge bending process or a pre-pressing process.

[0051] The structure of the edge bending unit 1100 for implementing edge bending will be described in detail.

[0052] refer to Figure 6 and Fig. 8A , the nip roller 1110 includes a roller body 1111 having a predetermined diameter and a pair of enlarged diameter portions 1113 provided at both ends of the roller body 1111, the enlarged diameter portion 1113 having a diameter larger than the diameter of the roller body 1111. Further, the anvil roller 1130 is disposed adjacent to the nip roller 1110 between the pair of enlarged diameter portions 1113 of the nip roller 1110. The rotational drive of the edge bending unit 1100 may be performed by a separate drive unit not shown in the figure. For example, the drive unit may be configured by applying a linear motor, an actuator, etc. that is capable of rotating the nip roller 1110 and the anvil roller 1130 around an axial direction. As Figure 6 As shown, a gap is provided between the nip roller 1110 and the anvil roller 1130. The electrode assembly 130 enters the edge bending unit 1100 in a width direction of the edge bending unit 1100, and the electrode assembly 130 passes through the gap between the nip roller 1110 and the anvil roller 1130.

[0053] In this case, the portion of the first electrode uncoated portion 132a of the first electrode plate 132 that protrudes upward in the longitudinal direction and the portion of the second electrode uncoated portion 134a of the second electrode plate 134 that protrudes downward in the longitudinal direction further protrude outward in the longitudinal direction of the anvil roller 1130. This portion of the first electrode uncoated portion 132a and this portion of the second electrode uncoated portion 134a contact the enlarged diameter portion 1113 of the nip roller 1110 in the process of passing through the gap. In this positional relationship, when the nip roller 1110 and the anvil roller 1130 rotate, the electrode assembly is pulled through the gap between the nip roller 1110 and the anvil roller 1130. Since the portions of the two uncoated portions 134a, 134b that protrude outward in the longitudinal direction of the anvil roller 1130 are pressed by the enlarged diameter portion 1113 of the nip roller 1110, the portions of the two uncoated portions 134a, 134b are folded at a predetermined inclination or bent at a predetermined curvature relative to the planes of the first electrode plate 132 and the second electrode plate 134. The bending occurs in one direction (i.e. Figure 5 In the same direction of the downward direction in the electrode assembly 130, both side edges in the longitudinal direction of the electrode assembly 130 (i.e., a portion of the first electrode uncoated portion 132a and a portion of the second electrode uncoated portion 134a) are bent in one direction to form bent edge portions 132b, 134b. In this case, the predetermined inclination is provided in the inclined portion 1115 (see Fig. 8A ) is an inclination angle. Further, the predetermined curvature is the arc portion R processed in the enlarged diameter portion 1113 (see Figure 8B ) curvature. In addition, one direction along which each electrode uncoated portion is folded is in the winding electrode assembly 130 so that the curved edge portions 132b, 134b are as follows during winding. Figure 7 The electrode assembly 130 is shown folded inwardly around the winding axis of the electrode assembly 130 based on the direction of the winding axis toward the winding axis. Accordingly, the electrode assembly 130 is discharged through the edge bending unit 1100 in a state where both ends are folded in one direction.

[0054] Fig. 8A and Figure 8B is a conceptual diagram illustrating an example of a curved edge portion of a winding roller structure according to an embodiment of the present disclosure.

[0055] like Fig. 8AAs shown, an inclined portion 1115 inclined at a predetermined angle relative to the roller body 1111 may be provided in the enlarged diameter portion 1113 of the nip roller 1110. The enlarged diameter portion 1113 is connected to the roller body 1111 through the inclined portion 1115. According to this structure, when the electrode assembly 130 enters the edge bending unit 1100, both side edges are pressed by the inclined portion 1115 and bent in one direction when the electrode assembly 130 passes through the above-mentioned gap.

[0056] Further, if Figure 8B As shown, the arc portion R may be processed at a predetermined curvature angle in the connection portion between the enlarged diameter portion 1113 of the nip roller 1110 and the roller body 1111. When the electrode assembly 130 enters the edge bending unit 1100, the edge is pressed by the enlarged diameter portion 1113 while being in close contact with the arc portion R, and thus may be bent into a curved surface having a predetermined curvature. In this case, the arc portion R may be formed not only in the nip roller 1110, but also in the anvil roller 1130 at a position facing the arc portion R of the nip roller 1110.

[0057] As described above, when the pre-pressing process is applied (i.e., the curved edge portions 132b, 134b are formed at both side edges of the electrode assembly 130 before winding), the protruding length of the base material can be reduced compared to the case where the pre-pressing process is not applied. Since the reduction in the protruding length of the base material means an increase in the coating area of ​​the active material, this has the effect of increasing the battery capacity without increasing the overall height of the electrode core.

[0058]

Table 1

[0059] Classification Positive electrode matrix material protrusion length Negative electrode matrix material protrusion length sum Traditional situation 2.0mm 2.5mm 4.5mm Improvements 0.75mm 0.75mm 1.5mm

[0060] That is, referring to Table 1, when pre-compression is not applied to the electrode assembly 130, a total base material protrusion of 4.5 mm is required to ensure a stable electrical connection with the cap assembly, but when pre-compression is applied to the electrode assembly 130 as in the present disclosure, a total base material protrusion of only 1.5 mm is required. Accordingly, since an internal space having a length of 3.0 mm can be ensured compared to the conventional case, the battery capacity can also be increased although the total height of the pole core remains unchanged. Further, when the pre-compression process is performed before winding, the overlap amount of the base material increases compared to the base material to which the pre-compression process is not applied. That is, when the pre-compression process is not applied, since the end portion of the base material is irregularly squeezed and bent, the height of the end portion of the base material or the overlap amount of the end portion is irregular. However, when the pre-compression process is applied, since the base material is bent in the same direction and thus the end portions of the base material overlap uniformly, the overlap amount of the end portion of the base material increases compared to the case where the pre-compression process is not performed. Furthermore, as the base material is uniformly bent, the tensile strength is improved because the height of the end portion of the base material is uniformly aligned and the amount of the base material to be welded when welding the current collector plate is increased. Accordingly, due to the uniform alignment of the base material, there is an effect of improving the resistance distribution and improving the welding quality.

[0061] Winding method using winding roller structure to achieve edge bending of electrode assembly

[0062] Hereinafter, a winding method for realizing edge bending of an electrode assembly according to an embodiment of the present disclosure will be described. The winding method of the present disclosure is a winding method for performing a winding process after performing a pre-compression process on an electrode assembly 130 including a first electrode plate 132, a second electrode plate 134, and a separator 137 disposed between the first electrode plate 132 and the second electrode plate 134. The winding method may include sequential execution of the following operations.

[0063] First, an operation of preparing an electrode assembly 130 is performed in which a first electrode plate 132 and a second electrode plate 134 are stacked on each other with a separator 137 therebetween so that a first electrode uncoated portion 132a of the first electrode plate 132 is exposed at one end in the longitudinal direction and a second electrode uncoated portion 134a of the second electrode plate 134 is exposed at the other end in the longitudinal direction. Figure 3 The electrode assembly 130 described is the same, so the description of the electrode assembly 130 is not repeated here.

[0064] Next, the electrode assembly 130 is first allowed to pass through the edge bending unit 1100 of the winding roller structure 1000 according to one embodiment of the present disclosure, and then an operation of bending the two side edges in the longitudinal direction of the electrode assembly 130 in one direction to form the bent edge portions 132b, 134b is performed. This operation is a process of folding the two side edges in the longitudinal direction of the electrode assembly 130. That is, a portion of the first electrode uncoated portion 132a and a portion of the second electrode uncoated portion 134a are bent inwardly toward the winding axis (edge ​​bending). As described above, this is also referred to as a pre-pressing process.

[0065] When the electrode assembly 130 enters the winding roll structure 1000 according to the present disclosure, the electrode assembly 130 first passes between the nip roller 1110 and the anvil roller 1130 constituting the edge bending unit 1100. When the electrode assembly 130 enters the edge bending unit 1100 in the width direction of the edge bending unit 1100 and passes through the gap provided between the nip roller 1110 and the anvil roller 1130, both side edges in the longitudinal direction of the electrode assembly 130 (i.e., a portion of the first electrode uncoated portion 132a of the first electrode plate 132 and a portion of the second electrode uncoated portion 134a of the second electrode plate 134) are pressed by the enlarged diameter portion 1113 of the nip roller 1110 and folded or bent in one direction.

[0066] Specifically, when the electrode assembly 130 is disposed at the front end in the direction of entering the edge bending unit 1100, the portion of the first electrode uncoated portion 132a of the first electrode plate 132 protruding upward in the longitudinal direction and the portion of the second electrode uncoated portion 134a of the second electrode plate 134 protruding downward in the longitudinal direction further protrude outward in the longitudinal direction of the anvil roller 1130 (see FIG. Figure 6 ). In this state, while the edge bending unit 1100 is driven and the electrode assembly 130 is pulled between the nip roller 1110 and the anvil roller 1130, the portions of the two uncoated portions 132a, 134a that protrude outward in the longitudinal direction of the anvil roller 1130 (i.e., a portion of the first electrode uncoated portion 132a and a portion of the second electrode uncoated portion 134a) contact the enlarged diameter portion 1113 of the nip roller 1110. Since the electrode assembly 130 is squeezed by the enlarged diameter portion 1113 of the nip roller 1110 as it continuously enters the gap between the nip roller 1110 and the anvil roller 1130, in one direction (i.e., Figure 6Accordingly, since a portion of the first electrode uncoated portion 132a and a portion of the second electrode uncoated portion 134a are folded at a predetermined inclination or bent at a predetermined curvature relative to the planes of the first electrode plate 132 and the second electrode plate 134, respectively, a portion of the first electrode uncoated portion 132a and a portion of the second electrode uncoated portion 134a are bent in one direction to form bent edge portions 132b, 134b.

[0067] Meanwhile, since the bent edge portions 132b, 134b prepared by the above process are a configuration in which a portion of the first electrode uncoated portion 132a and a portion of the second electrode uncoated portion 134a are bent, the first electrode uncoated portion 132a and the second electrode uncoated portion 134a can be each pressed by the inclined portion 1115 provided in each of the enlarged diameter portions 1113 of the nip roller 1110 and bent at a predetermined angle in one direction. That is, as Fig. 8A As shown, an inclined portion 1115 inclined at a predetermined angle may be provided in the enlarged diameter portion 1113 of the nip roller 1110, and when the electrode assembly 130 enters the edge bending unit 1100, both side edges are pressed by the inclined portion 1115 and bent in one direction when the electrode assembly 130 passes through the above-mentioned gap. Figure 8B As shown, since the arc portion R is processed with a predetermined curvature in the connecting portion between the enlarged diameter portion 1113 of the clamping roller 1110 and the roller body 1111, when the electrode assembly 130 enters the edge bending unit 1100, the edge is squeezed by the enlarged diameter portion 1113 while being in close contact with the arc portion R, and can thus be bent into a curved surface with a predetermined curvature.

[0068] Through the above process, after the entire electrode assembly 130 passes through the edge bending unit 1100, as shown in FIG. Figure 5 As shown, the electrode assembly 130 is discharged from the bending unit 1100 along the width direction in a state where both side edges in the longitudinal direction are folded in one direction. In this case, the one direction along which the bent edges are bent is a direction toward the winding axis of the electrode assembly 130.

[0069] Next, an operation of allowing the electrode assembly 130 formed with the curved edge portions 132b, 134b to pass through the winding unit 1700 of the winding roll structure 1000 to wind the electrode assembly 130 is performed. The electrode assembly 130 is wound into a circular shape while passing through the winding roll structure 1000 to form a core. In this case, as shown in FIG. Figure 5 As shown, the winding direction may be set so that the bent edge portions 132 b , 134 b of the electrode assembly 130 folded in one direction by the pre-compression process may be oriented in a direction toward the winding axis.

[0070] Next, an operation of compressing the electrode assembly 130 in the longitudinal direction may be performed. As the electrode assembly 130 on which the pre-compression process and the winding process are previously performed is compressed in the longitudinal direction thereof, the protruding matrix substance is in the form of covering both longitudinal ends of the core.

[0071] After performing the pre-compression process and the winding process, as in a general secondary battery manufacturing process, the first collector plate 121 and the second collector plate 122 (as described above) may be connected to the first electrode uncoated portion 132a and the second electrode uncoated portion 134a, respectively. Accordingly, the terminal 150 and the case 110 are electrically connected to the electrode assembly 130.

[0072] As described above, when the electrode assembly 130 passes between the edge bending unit 1100 and the winding unit 1700 in the winding roll structure 1000 for performing edge bending of the electrode assembly 130 according to the present disclosure, the operation of bending both side edges in the longitudinal direction of the electrode assembly 130 in one direction to form the bent edge portions 132b, 134b (pre-pressing process) and allowing the electrode assembly 130 formed with the bent edge portions 132b, 134b to pass through the winding unit 1700 of the winding roll structure 1000 to wind the electrode assembly 130 (winding process) is sequentially and continuously performed. Accordingly, since the pre-pressing process and the winding process are performed in one device without preparing a separate device / device for performing the pre-pressing process, there is an advantage that process efficiency can be maximized.

[0073] According to one embodiment of the present disclosure, when a cylindrical pole core is formed by winding an electrode assembly, since a pre-compression process of folding the base material protruding on two longitudinal sides of the electrode assembly in one direction is performed before winding, the battery capacity can be increased by reducing the protruding length of the base material required for welding with the collector plate.

[0074] The above description is merely an embodiment of a winding roller structure for realizing edge bending of an electrode assembly according to the present disclosure and a winding method using the winding roller structure, and the present disclosure is not limited to the above embodiments, and as claimed in the claims, the technical spirit of the present disclosure extends to the extent that a person skilled in the art can make various modifications without departing from the main purpose of the present disclosure.

Claims

1. A winding roller structure configured to wind an electrode assembly including a first electrode plate, a second electrode plate, and a separator disposed between the first electrode plate and the second electrode plate, the winding roller structure comprising: an edge bending unit configured to bend two side edges on opposite sides of the electrode assembly in a longitudinal direction of the electrode assembly, the edge bending unit comprising a nip roller and an anvil roller each extending in the longitudinal direction of the edge bending unit and arranged parallel to each other, the nip roller comprising a roller body and enlarged diameter portions provided at opposite ends of the roller body, the enlarged diameter portions each having a diameter larger than a diameter of the roller body, and the anvil roller being disposed adjacent to the nip roller between the enlarged diameter portions; as well as a winding unit configured to wind the electrode assembly having passed through the edge bending unit, The edge bending unit is configured such that, when the electrode assembly passes between the nip roller and the anvil roller, the two side edges of the electrode assembly are bent in one direction.

2. The winding roller structure according to claim 1, wherein the enlarged diameter portions of the nip roller each include an inclined portion that is inclined at a predetermined angle relative to the roller main body and connected to the roller main body; and The edge bending unit is configured such that, when the electrode assembly enters the edge bending unit, the two side edges of the electrode assembly are pressed by the inclined portion and bent in the one direction. 3 . The winding roll structure of claim 1 , wherein the edge bending unit is configured to bend the two side edges of the electrode assembly in the same direction.

4. A winding method for a wound electrode assembly, the electrode assembly comprising a first electrode plate, a second electrode plate, and a separator disposed between the first electrode plate and the second electrode plate, the winding method comprising: preparing the electrode assembly by stacking the first electrode plate and the second electrode plate on each other with the separator therebetween so that a first electrode uncoated portion of the first electrode plate is exposed at a first end in a longitudinal direction and a second electrode uncoated portion of the second electrode plate is exposed at a second end in the longitudinal direction; Passing the electrode assembly through the edge bending unit of the winding roller structure according to any one of claims 1 and 2, both side edges of the electrode assembly in the longitudinal direction are bent to form bent edge portions; as well as The electrode assembly having the bent edge portion is passed through the winding unit of the winding roller structure to wind the electrode assembly. 5 . The winding method according to claim 4 , wherein the two side edges are bent in a direction toward a winding axis of the electrode assembly.

6. The winding method according to claim 4, wherein: In the forming of the bent edge portion, when the electrode assembly passes through a gap provided between the nip roller and the anvil roller, the two side edges are pressed and bent by the enlarged diameter portion of the nip roller.

7. The winding method according to claim 6, wherein the two side edges are the first electrode uncoated portion and the second electrode uncoated portion, respectively, and wherein the first electrode uncoated portion and the second electrode uncoated portion are pressed by an inclined portion provided in the enlarged diameter portion of the nip roller and bent at a predetermined angle.

8. The winding method according to claim 4, wherein the two side edges of the electrode assembly are bent in the same direction, and Wherein when the electrode assembly passes through a gap provided between the nip roller and the anvil roller, the first electrode uncoated portion and the second electrode uncoated portion are bent in one direction.

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