Electrode assembly and secondary battery including the same

Abstract

The present invention allows the deformation portion to deform as the usage time of the secondary battery increases, thereby suppressing deformation near the positive electrode end, thereby preventing damage to the adjacent separator. In an electrode assembly according to the present invention, a first electrode sheet, a second electrode sheet, and a separator disposed between the first and second electrode sheets are wound together, and the first electrode sheet may include a deformed portion disposed a predetermined distance from one end of the second electrode sheet in a winding direction and protruding toward a center in a wound state.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0132752 filed on October 14, 2022 and Korean Patent Application No. 10-2023-0137082 filed on October 13, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly and a secondary battery including the same. [Background technology]

[0003] In recent years, with rising energy prices due to the depletion of fossil fuels and growing concerns about environmental pollution, the demand for environmentally friendly alternative energy sources has become an essential factor for future life. Accordingly, research into various power generation technologies, such as solar, wind, and tidal power, has been ongoing, and there has also been great interest in power storage devices, such as batteries, to more efficiently use the electrical energy produced in this way.

[0004] Furthermore, with the increasing technological development and demand for battery-based electronic mobile devices and electric vehicles, the demand for batteries as an energy source is rapidly increasing, and a great deal of research is being conducted into batteries that can meet the resulting diverse demands.

[0005] Batteries that store electrical energy are generally classified as primary batteries and secondary batteries. While primary batteries are disposable, secondary batteries are rechargeable batteries manufactured using materials that allow repeated oxidation and reduction processes between electric current and materials. That is, when a reduction reaction occurs in a material due to electric current, the power source is charged, and when an oxidation reaction occurs in the material, the power source is discharged. Electricity is generated as this charge-discharge cycle is repeated.

[0006] Secondary batteries can be roughly classified according to the shape of the battery case into cylindrical batteries in which the electrode assembly is housed in a cylindrical metal can, prismatic batteries in which the electrode assembly is housed in a prismatic metal can, and pouch-type batteries in which the electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet.

[0007] Among these, the cylindrical battery may have a jelly-roll-like electrode assembly in which a positive electrode, a negative electrode, and a separator are wound together and disposed inside a case.

[0008] FIG. 1 is a cross-sectional view schematically illustrating a cross section of a modified conventional electrode assembly 1, and FIG. 2 is a side view schematically illustrating a negative electrode 2 constituting the conventional electrode assembly 1.

[0009] The electrode assembly 1 included in a conventional cylindrical secondary battery may have a structure in which a positive electrode, a negative electrode, and a separator are wound together. In this case, the positive electrode may be wound slower than the negative electrode so that one end of the positive electrode is positioned further outward from the center than one end of the negative electrode when the electrode assembly 1 is wound.

[0010] Referring to FIG. 1, a conventional secondary battery may deform due to empty space formed in the center during use. In particular, the electrode assembly 1 of a conventional cylindrical secondary battery is most deformed at the positive electrode end. This can cause damage to the adjacent separator, which can lead to short circuits and reduced lifespan and performance of the secondary battery.

[0011] Referring to FIG. 2, the negative electrode 2 included in the electrode assembly 1 of a conventional cylindrical secondary battery may have a shape in which a negative electrode tab is disposed in a substantially rectangular plate shape. One end of the negative electrode may be tape-attached. Specifically, the tape may refer to insulating tape for insulation. Here, the tape may serve to ensure insulation performance and protect the negative electrode tab. Therefore, the conventional negative electrode 2 does not have a structure to prevent the problem of the positive electrode end deforming during use of the secondary battery damaging the adjacent separator.

[0012] Therefore, there is a need for an electrode assembly and a secondary battery including the same that can reduce the risk of the separator being damaged by the positive electrode end due to deformation of the electrode assembly. Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been devised to solve the above problems, and an object of the present invention is to provide an electrode assembly and a secondary battery including the same that can prevent damage to an adjacent separator due to deformation of a positive electrode end, thereby improving safety and performance. [Means for solving the problem]

[0014] In an electrode assembly according to the present invention, a first electrode sheet, a second electrode sheet, and a separator disposed between the first and second electrode sheets are wound together, and the first electrode sheet may include a deformed portion disposed a predetermined distance from one end of the second electrode sheet in a winding direction and protruding toward a center in a wound state.

[0015] The first electrode sheet may further include an uncoated portion disposed at one end of the current collector, where an electrode tab is provided on one side of the current collector, and a coated portion where an active material is applied to both sides of the current collector.

[0016] The second electrode sheet may be disposed at a position facing the grounded portion of the first electrode sheet with the separator interposed therebetween.

[0017] The deformed portion may be disposed between the electrode tab and the grounded portion in the uncoated portion so as to be spaced from the electrode tab.

[0018] The first electrode sheet may further include a cover attached to the plain portion, and the cover may have thermosetting properties.

[0019] The cover portion may be attached so as to be wound around at least once.

[0020] The cover portion may have a thickness of 40 μm or more and 100 μm or less.

[0021] The cover may include a first cover attached to one side of the non-coating portion to cover a portion of the electrode tab, and a second cover attached to the other side of the non-coating portion.

[0022] The first cover part may be attached by a length that is shorter than the length of the second cover part.

[0023] The first electrode sheet may further include a fixing portion attached to a surface of the deforming portion opposite to a protruding direction of the deforming portion, and the fixing portion may have thermosetting properties.

[0024] The deformed portion may have a curved shape while maintaining a constant radius of curvature.

[0025] The deformed portion may have a radius of curvature of 0.05 mm or more and 0.8 mm or less.

[0026] The first electrode sheet may induce the degree of deformation of the deformation portion to increase as the duration of use increases.

[0027] The secondary battery according to the present invention includes an electrode assembly in which a first electrode sheet, a second electrode sheet, and a separator disposed between the first and second electrode sheets are wound together, and an exterior housing that houses the electrode assembly, and the first electrode sheet may include a deformation portion that is disposed a predetermined distance from one end of the second electrode sheet and that protrudes toward the center of the wound electrode sheet. [Effects of the Invention]

[0028] In an electrode assembly according to the present invention, a first electrode sheet, a second electrode sheet, and a separator disposed between the first and second electrode sheets are wound together, and the first electrode sheet may include a deformed portion disposed a predetermined distance from one end of the second electrode sheet in a winding direction and protruding toward a center in a wound state.

[0029] As a result, the deformation portion is deformed as the usage time of the secondary battery increases, suppressing deformation near the positive electrode end, thereby preventing damage to the adjacent separator.

[0030] In addition, damage to the separator can be prevented, thereby improving the safety and performance of the secondary battery including the electrode assembly.

[0031] The effects of the present invention are not limited to the above-mentioned examples, and various other effects may be included within the present specification. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view schematically illustrating a cross section of a modified conventional electrode assembly. [Figure 2] 1 is a side view schematically illustrating a negative electrode constituting a conventional electrode assembly. [Figure 3] 1 is a cross-sectional view schematically illustrating a wound electrode assembly according to a first embodiment of the present invention. [Figure 4] 1 is an exploded view schematically illustrating an electrode assembly according to a first embodiment of the present invention before being wound up. [Figure 5] 1 is a side view schematically illustrating a first electrode sheet according to a first embodiment of the present invention. [Figure 6] 1 is a side view schematically illustrating a first electrode sheet according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand the present invention. However, the present invention may be embodied in various different forms and is not limited to the following embodiments.

[0034] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention will be omitted, and in this specification, when adding reference numbers to components in each drawing, the same or similar reference numbers will be used throughout the specification for the same or similar components.

[0035] Furthermore, the terms and words used in this specification and claims should not be interpreted in a way that is limited to their ordinary and dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that the inventor himself / herself can appropriately define the concept of a term in order to explain the invention in the best possible way.

[0036] Example 1 The present invention provides an electrode assembly 10 as a first embodiment.

[0037] Fig. 3 is a cross-sectional view schematically illustrating the wound state of the electrode assembly 10 according to the first embodiment of the present invention. Fig. 4 is an exploded view schematically illustrating the state of the electrode assembly 10 according to the first embodiment of the present invention before being wound, and Fig. 5 is a side view schematically illustrating the first electrode sheet 100 according to the first embodiment of the present invention.

[0038] The electrode assembly 10 according to the first embodiment of the present invention may be used to manufacture a secondary battery. Here, the electrode assembly 10 may refer to an electrode assembly having a wound structure, and the secondary battery may refer to a cylindrical secondary battery.

[0039] 3, the electrode assembly 10 according to the first embodiment of the present invention may include a first electrode sheet 100, a second electrode sheet 200, and a separator 300. Specifically, the electrode assembly 10 may have a structure in which the separator 300 is disposed between the first electrode sheet 100 and the second electrode sheet 200, and the first electrode sheet 100, the second electrode sheet 200, and the separator 300 are wound together. Here, the first electrode sheet 100 may refer to a negative electrode sheet, and the second electrode sheet 200 may refer to a positive electrode sheet.

[0040] The conventional electrode assembly 1 has a problem in that deformation of the vicinity of one end of the positive electrode sheet becomes severe as the secondary battery is used. Therefore, as an example of a configuration for preventing deformation of the vicinity of one end of the positive electrode sheet, the first electrode sheet 100 of the electrode assembly 10 according to the first embodiment of the present invention may include a deformation portion 130.

[0041] The deforming portion 130 of the first electrode sheet 100 may be disposed a predetermined distance from one end of the second electrode sheet 200 and may protrude toward the center in a wound state. Specifically, the deforming portion 130 of the first electrode sheet 100 may be disposed a predetermined distance from one end of the second electrode sheet 200 in the winding direction. The deforming portion 130 may serve to preferentially deform the second electrode sheet 200 so that the one end of the second electrode sheet 200 is not deformed. The first electrode sheet 100 according to the first embodiment of the present invention may induce an increase in the degree of deformation of the deforming portion 130 as the usage time of the secondary battery increases. Referring to FIG. 3, it can be seen that in the wound electrode assembly 10, the deforming portion 130 is disposed at a position spaced apart from one end of the second electrode sheet 200 in the winding direction. In this regard, when experimentally observing the deformation process of the electrode assembly 10 inside a cylindrical secondary battery, it can be seen that the degree of deformation continues to increase in the area where the deformation occurs. That is, as the use time increases, deformation of the electrode assembly 10 may become more severe in the deformed portion. Without the deforming portion 130, deformation near one end of the second electrode sheet 200 may become more severe mainly during use of the secondary battery, and the deformed end of the second electrode sheet 200 may damage the adjacent separator 300. Therefore, the first electrode sheet 100 of the electrode assembly 10 according to the first embodiment of the present invention is disposed a certain distance away from one end of the second electrode sheet 200 in the winding direction, thereby inducing more severe deformation in portions other than the one end of the second electrode sheet 200 and preventing deformation near the one end of the second electrode sheet 200. This prevents damage to the separator and prevents additional problems, such as short circuits, caused by the damaged separator.

[0042] The shape of the deformable portion 130 of the first electrode sheet 100 may vary, but the deformable portion 130 according to the first embodiment of the present invention may have a curved shape while maintaining a constant radius of curvature. Specifically, the deformable portion 130 may have a substantially semicircular shape. Preferably, the radius of curvature of the deformable portion 130 may be 0.05 mm or more and 0.8 mm or less.

[0043] Meanwhile, the electrode assembly 10 included in a cylindrical secondary battery may have a wound jelly-roll shape. To achieve this shape, the first electrode sheet 100, the second electrode sheet 200, and the separator 300, each of which is generally sheet-shaped, may be wound together. In this case, a generally cylindrical winding core may be disposed inside the battery for winding. When the deformed portion 130 has a generally semicircular shape, using the winding core allows the deformed portion 130 to be formed through a relatively simple process. Specifically, the deformed portion 130 may be formed by pressing the portion of the first electrode sheet 100 where the deformed portion 130 is to be formed with the winding core before winding. This is merely one example of how to form the deformed portion 130, and other methods may be used.

[0044] Meanwhile, the deformed portion 130 having an approximately semicircular shape may be formed on the first electrode sheet 100 using a cylindrical rod other than a winding core. In this case, the deformed portion 130 should not be formed too large so as not to interfere with winding. If the radius of curvature of the deformed portion 130 is too large, problems may occur during the winding process to form the electrode assembly 10. In consideration of this, the deformed portion 130 may be formed to have a radius of curvature that is approximately half or less of the radius of the rod. In this regard, since a winding core with a radius of approximately 1.6 mm is typically used during the winding process, the preferred radius of curvature of the deformed portion 130 may be approximately 0.8 mm or less, taking into consideration the winding form.

[0045] On the other hand, if the radius of curvature of the deforming portion 130 is very small, the effect of the present invention may not be achieved by the deforming portion 130. Therefore, the radius of curvature of the deforming portion 130 having a substantially semicircular shape may be approximately 0.05 mm or more.

[0046] 4 and 5, the first electrode sheet 100 of the electrode assembly 10 according to the first embodiment of the present invention may include an uncoated portion 110 and a coated portion 120. Specifically, the uncoated portion 110 of the first electrode sheet 100 may be disposed at one end and have an electrode tab 103 provided on one side of the current collector 101, and the coated portion 120 may have an active material 102 coated on both sides of the current collector 101. More specifically, the uncoated portion 110 may be a portion of the current collector 101 that is not coated with the active material 102, and the coated portion 120 may be a portion of the current collector 101 that is coated with the active material 102. Here, the current collector 101 may be a negative electrode current collector having a substantially thin plate shape and may contain copper (Cu).

[0047] Meanwhile, to more specifically describe the position where the deformed portion 130 is disposed in the wound electrode assembly 10, the positional relationship between the components of the electrode assembly 10 will be described as follows. Referring to Fig. 4, the second electrode sheet 200 of the electrode assembly 10 according to the first embodiment of the present invention may be disposed in a position facing the ground portion 120 of the first electrode sheet 100, with the separator 300 sandwiched therebetween. Specifically, the first electrode sheet 100 may be wound first, and then the second electrode sheet 200 may be wound together.

[0048] The separator may be disposed between the first electrode sheet 100 and the second electrode sheet 200 to separate the first electrode sheet 100 and the second electrode sheet 200. To separate the first electrode sheet 100 and the second electrode sheet 200, a separator 300 may be additionally disposed during the winding process.

[0049] Meanwhile, as an example of a configuration for suppressing deformation of the electrode assembly 10, the first electrode sheet 100 according to the first embodiment of the present invention may further include a cover part 140.

[0050] 5, the cover 140 may be attached to the uncoated portion 110 of the first electrode sheet 100 and may have thermosetting properties. Specifically, the cover 140 may be a thermosetting tape. Thermosetting may mean a property of being hardened when heat is applied.

[0051] Furthermore, the cover portion 140 of the first electrode sheet 100 may have a thickness of approximately 40 μm or more and 100 μm or less. As described above, the cover portion 140 may be a thermosetting tape, and a thickness of 40 μm or more and 100 μm or less may be a condition for a thermosetting tape that can be relatively easily obtained.

[0052] In the manufacturing process of the electrode assembly 10, a process of forming a central hole using a heated object may be performed to form an empty space. The heat transferred in this process may harden the thermosetting cover 140. Specifically, the cover 140 may be made of a material that begins to harden at approximately 100°C.

[0053] The heat-hardened cover portion 140 can not only suppress deformation of one end of the second electrode sheet 200, but also suppress deformation of the electrode assembly 10 itself by providing reinforcement in rigidity.

[0054] Meanwhile, the cover part 140 may be formed by being attached from one end of the first electrode sheet 100, or may be formed by being attached from a point approximately 3 to 4 mm away from the one end for process efficiency.

[0055] As an example of a configuration for efficiently suppressing deformation of the electrode assembly 10, the cover portion 140 of the first electrode sheet 100 according to the first embodiment of the present invention may include a first cover portion 141 and a second cover portion 142. The first cover portion 141 may be attached to one side of the non-coating portion 110 to cover a portion of the electrode tab 103, and the second cover portion 142 may be attached to the other side of the non-coating portion 110. Therefore, the first cover portion 141 and the second cover portion 142 may be attached to both sides of the current collector 101 with the current collector 101 sandwiched therebetween. Here, the first cover portion 141 may be attached to the current collector 101 by a length shorter than the length of the second cover portion 142.

[0056] Since the first cover part 141 and the second cover part 142 are arranged on both sides, the degree to which the cover part 140 suppresses deformation of the electrode assembly 10 can be strengthened.

[0057] As an example of a configuration for suppressing deformation of the electrode assembly 10 over a relatively wide range, the cover portion 140 of the first electrode sheet 100 according to the first embodiment of the present invention may be attached so as to be wound at least once. That is, in the wound state, the plain portion 110 of the first electrode sheet 100 may have a shape that is wound one or more times.

[0058] When the cover part 140 is attached at least once, deformation of the electrode assembly 10 can be suppressed over a wide range.

[0059] Meanwhile, since the deforming portion 130 is a portion that induces deformation rather than deforming one end of the second electrode sheet 200, the cover portion 140 may not be attached. Therefore, according to the first embodiment of the present invention, the deforming portion 130 may be disposed between the uncoated portion 110 and the covered portion 120 so that the cover portion 140 can be easily attached only to the uncoated portion 110. Specifically, referring to FIG. 5 , the first electrode sheet 100 may be disposed in the following order from one end: the uncoated portion 110, the deforming portion 130, and the covered portion 120. Here, for convenience of explanation, the portion of the first electrode sheet 100 to which the active material 102 is not applied, excluding the deforming portion 130, is referred to as the uncoated portion 110. However, more accurately, the deforming portion 130 may be part of the uncoated portion 110. That is, the deforming portion 130 may be formed at an end of the uncoated portion 110 adjacent to the covered portion 120. Therefore, the deformed portion 130 may be disposed between the electrode tab 103 and the grounded portion 120 in the uncoated portion 110 so as to have a gap between the electrode tab 103 and the grounded portion 120 .

[0060] In the electrode assembly 10 according to the first embodiment of the present invention, the deformation portion 130 is deformed as the use time of the secondary battery increases, thereby suppressing deformation near the end of the second electrode sheet 200 and thereby preventing damage to the adjacent separator 300. In addition, by preventing damage to the separator 300, the safety and performance of the secondary battery including the electrode assembly 10 can be improved.

[0061] Meanwhile, a secondary battery with improved safety and performance may be manufactured by housing the electrode assembly 10 according to the first embodiment of the present invention in a wound state inside an exterior part. In this case, the secondary battery may be a cylindrical secondary battery, and the exterior part may have a substantially cylindrical can shape.

[0062] Example 2 The present invention provides an electrode assembly including a first electrode sheet 100' in another form as a second embodiment.

[0063] The first electrode sheet 100' of the electrode assembly according to the second embodiment of the present invention may differ from the first electrode sheet 100 according to the first embodiment in terms of whether or not a fixing portion 150 is present.

[0064] Hereinafter, detailed description of the same components as those of the electrode assembly 10 according to the first embodiment of the present invention will be omitted.

[0065] FIG. 6 is a side view schematically illustrating a first electrode sheet 100' according to a second embodiment of the present invention.

[0066] The first electrode sheet 100′ of the electrode assembly according to the second embodiment of the present invention may further include a fixing portion 150 attached to the deforming portion 130′. Specifically, the fixing portion 150 may be attached to the side of the deforming portion 130′ opposite to the protruding direction of the deforming portion 130′, and may have thermosetting properties similar to the cover portion 140. In this case, the fixing portion 150 may be a thermosetting tape. Furthermore, the fixing portion 150 may have a thickness of approximately 40 μm to 100 μm, similar to the cover portion 140 described above.

[0067] Similar to the cover part 140, the fixing part 150 may be hardened by heat transferred during a process of forming a central hole with a heated object to form a central empty space during a manufacturing process of the electrode assembly. Specifically, the fixing part 150 may be made of a material that begins to harden at approximately 100°C.

[0068] 6, the fixing portion 150 may be attached to the concave surface of the deforming portion 130'. Therefore, the electrode assembly according to the second embodiment of the present invention includes the fixing portion 150, and can guide the deformation of the deforming portion 130' to proceed in a direction toward the convex surface.

[0069] In this regard, when the fixing portion 150 is hardened by heat at the deforming portion 130', the convex surface to which the fixing portion 150 is not attached may have a weaker fixing force that allows the fixing portion 150 to maintain a relatively uniform shape compared to the other concave surface to which the fixing portion 150 is attached. Therefore, the first electrode sheet can be relatively efficiently induced to deform in the direction of the surface to which the deforming portion 130' is not attached.

[0070] Although the present invention has been described above using limited examples and drawings, the present invention is not limited thereto, and various implementations are possible within the technical spirit of the present invention and the scope of the claims set forth below by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0071] 1. Conventional electrode assembly 2 Conventional anode 10 Electrode assembly 100, 100' First electrode sheet 101 Current collector 102 Active material 103 Electrode tab 110 Plain section 120 Landed section 130, 130' Deformed section 140 Cover 141 First cover part 142 Second cover part 150 Fixed part 200 Second electrode sheet 300 Separation membrane

Claims

1. An electrode assembly having a structure in which a first electrode sheet, a second electrode sheet, and a separator disposed between the first electrode sheet and the second electrode sheet are wound together, The first electrode sheet is an electrode assembly including a deformed portion disposed at a predetermined distance in a winding direction from one end of the second electrode sheet and protruding toward a center of the wound electrode sheet;

2. The first electrode sheet is a blank portion disposed at one end of the current collector and having an electrode tab on one side thereof; The electrode assembly of claim 1 , further comprising a land portion in which an active material is applied to both sides of the current collector.

3. The second electrode sheet is The electrode assembly according to claim 2 , wherein the separator is disposed at a position facing the landed portion of the first electrode sheet with the separator interposed therebetween.

4. The deformation portion is The electrode assembly according to claim 2 , wherein the electrode tab is disposed at the uncoated portion between the electrode tab and the grounded portion so as to have a gap therebetween.

5. The first electrode sheet is The cover further includes a cover attached to the plain portion. The electrode assembly according to claim 2 , wherein the cover portion has a thermosetting property.

6. The cover portion is The electrode assembly of claim 5 , wherein the electrode assembly is attached so as to have at least one wrap.

7. The cover portion is The electrode assembly according to claim 5 , wherein the thickness is 40 μm or more and 100 μm or less.

8. The cover portion is a first cover portion attached to one surface of the non-coating portion and covering a portion of the electrode tab; The electrode assembly of claim 5 , further comprising: a second cover portion attached to the other surface of the non-coating portion.

9. The first cover portion is The electrode assembly of claim 8 , wherein the second cover portion is attached by a length shorter than the length of the second cover portion.

10. The first electrode sheet is The deforming portion may further include a fixing portion attached to a surface opposite to a protruding direction of the deforming portion, The electrode assembly according to claim 1 , wherein the fixing portion has a thermosetting property.

11. The deformation portion is The electrode assembly of claim 1 , wherein the electrode assembly has a curved configuration while maintaining a constant radius of curvature.

12. The deformation portion is The electrode assembly according to claim 11, wherein the radius of curvature is 0.05 mm or more and 0.8 mm or less.

13. The first electrode sheet is The electrode assembly of claim 1 , wherein the degree of deformation of the deformation portion increases as the duration of use increases.

14. an electrode assembly having a structure in which a first electrode sheet, a second electrode sheet, and a separator disposed between the first electrode sheet and the second electrode sheet are wound together; an exterior part that houses the electrode assembly therein, The first electrode sheet is a deformed portion disposed at a predetermined distance from one end of the second electrode sheet and protruding toward a center of the wound electrode sheet;

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