Secondary batteries

Abstract

To provide a secondary battery in which the bent shape of an electrode lead is improved and the internal space use efficiency of the case and the energy density can be improved.SOLUTION: One example of a secondary battery includes an electrode assembly including a current collecting tab projecting to one side, a case including a main body where an accommodation part to accommodate the electrode assembly is formed and a cover to cover the main body, and an electrode lead electrically connected to the current collecting tab and extracted to the outside of the case. The current collecting tab is bent twice. The length of the current collecting tab is twice the thickness of the electrode assembly.SELECTED DRAWING: Figure 2c

Description

[Technical Field]

[0001] The present invention relates to a secondary battery. [Background technology]

[0002] Secondary batteries are batteries that can be charged and discharged, unlike primary batteries, which cannot be recharged. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, tablet computers, laptops, digital cameras, and video cameras, while high-capacity secondary batteries are widely used as motor drive and power storage batteries in hybrid and electric vehicles.

[0003] Such a secondary battery may include an electrode assembly consisting of a negative electrode and a positive electrode, a case for housing the electrode assembly, and terminals connected to the electrode assembly. Secondary batteries may be classified into circular, rectangular, and pouch-shaped types depending on their shape. Among these, pouch-shaped secondary batteries may be formed using a lightweight pouch exterior material that can be easily transformed into various shapes.

[0004] The information disclosed in the background of the invention above is intended to enhance understanding of the background of the invention only, and may therefore include information that does not constitute prior art. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a secondary battery that can improve the bent shape of the electrode leads and increase the utilization rate of the internal space of the case and the energy density. [Means for solving the problem]

[0006] The secondary battery according to the present invention includes an electrode assembly including a current collecting tab having a folded portion formed by folding it at least once and having a folded end protruding from the folded end; a case including a body having a receiving portion for receiving the electrode assembly and a cover for covering the body; and an electrode lead electrically connected to the end of the current collecting tab and extending to the outside of the case, and may further include an adhesive member formed corresponding to the folded portion.

[0007] Here, the adhesive member can be formed on the inner surface of the folded portion.

[0008] The adhesive member can fix the shape of the bent portion to the outside of the electrode assembly.

[0009] The adhesive member may also be accommodated in an area formed by folding the folded portion to form a recess.

[0010] Also, the adhesive member may not be provided at the end where the current collecting tab is connected to the electrode lead.

[0011] The adhesive member may also be formed so as to fill the inside of the folded portion and be formed below the end of the current collecting tab.

[0012] Also, the adhesive member may be formed on both the inner and outer surfaces of the folded portion of the current collecting tab.

[0013] The adhesive member can also bond the folded portion of the current collecting tab to the outer surface of the electrode assembly.

[0014] The adhesive member may also include a UV adhesive.

[0015] The adhesive member may also be configured to include an acrylate-based UV adhesive.

[0016] In addition, a method for manufacturing a secondary battery according to the present invention may include the steps of: providing an electrode assembly including a current collecting tab having a folded portion formed by folding it at least once and having a folded end protruding from the folded end; electrically connecting an electrode lead to the end of the current collecting tab; injecting an adhesive member formed corresponding to the folded portion; and curing the adhesive member.

[0017] Here, the adhesive material can be injected onto the inner surface of the folded portion through an injection nozzle.

[0018] The current collecting tab having the bent portion is dipped into the container provided with the adhesive, and the adhesive can be poured in accordance with the bent portion.

[0019] The method may also include a step of using a pusher to apply pressure to the bent portion into which the adhesive material has been poured, thereby tightly fitting the shape of the bent portion to the electrode assembly.

[0020] The adhesive member may be made of a UV adhesive, and the adhesive member may be cured by irradiating it with light from a lamp.

[0021] The pusher may also be formed with a convex or concave pressure-applying end. [Effects of the Invention]

[0022] In the secondary battery according to an embodiment of the present invention, the current collecting tab is folded and fixed between the folded portions using an adhesive member, thereby increasing the space utilization rate of the electrode assembly above the folded portion of the current collecting tab and preventing the current collecting tab from loosening or floating after folding. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a perspective view illustrating a secondary battery according to an embodiment of the present invention; [Figure 2a]1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2b] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2c] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2d] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2e] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2f] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2g] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2h] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2i] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 2j] 1 illustrates a manufacturing process of a secondary battery according to an embodiment of the present invention. [Figure 3a] 10 illustrates a manufacturing process of a secondary battery according to another embodiment of the present invention. [Figure 3b] 10 illustrates a manufacturing process of a secondary battery according to another embodiment of the present invention. [Figure 3c] 10 illustrates a manufacturing process of a secondary battery according to another embodiment of the present invention. [Figure 3d] 10 illustrates a manufacturing process of a secondary battery according to another embodiment of the present invention. [Figure 4a] 3 is a photograph comparing the shape of a secondary battery according to an embodiment of the present invention with an existing structure; [Figure 4b] 3 is a photograph comparing the shape of a secondary battery according to an embodiment of the present invention with an existing structure; DETAILED DESCRIPTION OF THE INVENTION

[0024] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as meanings and concepts consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concepts of terms in order to best describe his or her invention. Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely some of the most preferred embodiments of the present invention and do not fully represent the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modifications may exist as of the time of filing this application. Furthermore, as used in this specification, the words "comprise," "include," and / or "comprising," "including," specify the presence of a stated shape, number, step, operation, member, element, and / or group thereof, but do not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements, and / or groups. Furthermore, when describing an embodiment of the present invention, the words "may" and "may" can include "one or more embodiments of the present invention."

[0025] In order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0026] A statement that two comparison objects are "identical" means that they are "substantially identical." Therefore, "substantially identical" can include deviations that are considered low in the art, for example, deviations within 5%. Furthermore, "uniformity of a parameter in a given region" can mean uniformity on average.

[0027] Even if terms such as "first," "second," etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and it goes without saying that a first component may also be a second component unless otherwise specified.

[0028] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0029] When any structure is disposed "on (or under)" a component or "above (or below)" a component, it can mean not only that the structure is disposed in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and any structure disposed on (or below) the component.

[0030] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, or that other components may be "interposed" between the components, or that each component may be "coupled," "coupled," or "connected" through other components. Furthermore, when a part is said to be electrically coupled to another part, this includes not only direct coupling, but also coupling via an intermediate element.

[0031] Throughout the specification, when "A and / or B" is used, this means A only, B only, or A and B, unless specifically stated to the contrary. That is, "and / or" includes all or any combination of the listed items. When "C through D" is used, this means at least C and at most D, unless specifically stated to the contrary.

[0032] FIG. 1 is a perspective view illustrating a secondary battery according to an embodiment of the present invention.

[0033] Referring to FIG. 1, a secondary battery 100 according to an embodiment of the present invention includes an electrode assembly 110, a case 120, and an electrode lead 130.

[0034] The electrode assembly 110 can include a first electrode plate, a second electrode plate, and a separator, where the first electrode plate can act as a negative electrode and the second electrode plate can act as a positive electrode.

[0035] The first electrode plate is formed by applying a first electrode active material such as graphite or carbon to a first electrode current collector made of a metal foil such as copper or nickel, and includes a first electrode uncoated area, which is an area where the first active material is not applied. The first electrode uncoated area provides a path for current flow between the first electrode plate and the outside.

[0036] The second electrode plate is formed by applying a second electrode active material such as a transition metal oxide to a second electrode current collector formed of a metal foil such as aluminum, and includes a second electrode uncoated portion, which is an area where the second active material is not applied.

[0037] In addition, the first electrode uncoated portion may form first current collecting tabs 111. A plurality of first current collecting tabs 111 may be provided and formed to protrude from the first electrode plate. The first current collecting tabs 111 may be formed to protrude in a certain direction from the first electrode plate and overlap on one side.

[0038] In addition, the second electrode uncoated portion may form second current collecting tabs 112. A plurality of second current collecting tabs 112 may be provided and formed to protrude from the second electrode plate. The second current collecting tabs 112 may be formed to protrude in a certain direction from the second electrode plate and overlap on one side. The second current collecting tabs 112 may protrude in the same direction as the first current collecting tab 111 but may be positioned to be spaced apart from each other.

[0039] Meanwhile, the first current collecting tab 111 and the second current collecting tab 112 include bent portions 111a and 112a, respectively, and adhesive members 113 may be formed at the bent portions 111a and 112a, as will be described later. Accordingly, the bent shapes of the first current collecting tab 111 and the second current collecting tab 112 may be maintained, thereby improving the utilization rate of the internal space of the case and the energy density.

[0040] The first current collecting tab 111 and the second current collecting tab 112 may each include ends 111b, 112b where a number of protruding plain portions are gathered together. These ends 111b, 112b may be welded using a method such as ultrasonic welding so that the plain portions forming the first current collecting tab 111 and the second current collecting tab 112 are joined together without scattering. Electrode leads 130 may be joined to the ends 111b, 112b, respectively, and may protrude out of the case 120.

[0041] The separator is located between the first and second electrode plates and serves to prevent short circuits and allow lithium ions to migrate. The separator may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. In some examples, the separator may have a larger area than the first and second electrode plates to effectively prevent electrical short circuits between the first and second electrode plates.

[0042] The electrode assembly 110 may be housed in a case 120 together with an electrolyte. The electrolyte may be composed of an organic solvent such as EC (ethylene carbonate), PC (propylene carbonate), DEC (diethyl carbonate), EMC (ethyl methyl carbonate), or DMC (dimethyl carbonate) and a lithium salt such as LiPF6 or LiBF4. The electrolyte may be liquid, solid, or gel-like. The first current collecting tab 111 and the second current collecting tab 112 are electrically connected to the electrode lead 130, respectively.

[0043] The electrode assembly 110 may be configured as a stack type or a lamination type in which a first electrode plate, a separator, a second electrode plate, a separator, etc. are stacked in this order.

[0044] The case 120 may generally be comprised of a body 121 and a cover 122, which are formed by folding an integrally formed rectangular pouch film along the length of one side. Alternatively, the case 120 may be a separate pouch film with the folded portions of the body 121 and the cover 122 separated, rather than being an integral type. In some examples, the case 120 may include or be referred to as a pouch-type case or exterior material. In some examples, the case 120 may be a multilayer thin film made of a metal layer and insulating layers formed on both sides of the metal layer.

[0045] The body 121 may include a receiving portion 123, which is a groove that receives the electrode assembly 110. The body 121 may also include a sealing portion 124 that extends outward along the edge of the receiving portion 123. After the electrode assembly 110 is attached to the receiving portion 123, the case 120 may be sealed by heat sealing the edges of the sealing portion 124 and the cover 122 in close contact with each other. The sealing portion 124 is a portion where the body 121 and the cover 122 are fused together, and may extend flatly to a certain length.

[0046] The electrode leads 130 may be electrically coupled to the first current collecting tab 111 and the second current collecting tab 112, respectively. In some examples, the electrode lead 130 coupled to the first current collecting tab 111 may be a negative lead, and the electrode lead 130 coupled to the second current collecting tab 112 may be a positive lead. In some examples, the electrode leads 130 may include or be referred to as lead tabs, electrode terminals, or strip terminals.

[0047] The electrode lead 130 may be electrically connected to the ends 111b, 112b of the first current collecting tab 111 and the second current collecting tab 112, respectively, and may be drawn out to the outside of the case 120. In some examples, the electrode lead 130 may be electrically connected to the first current collecting tab 111 and the second current collecting tab 112 by welding. In some examples, the electrode lead 130 may be drawn out to the outside through a gap between the sealing portion 124 of the main body 121 and the cover 122. For example, one end of the electrode lead 130 may be connected to the first current collecting tab 111 or the second current collecting tab 112, and the other end of the electrode lead 130 may be drawn out to the outside of the case 120. In some examples, the other end of the electrode lead 130 that is drawn out to the outside may be referred to as a drawn portion.

[0048] The electrode lead 130 may further include an insulating member 135 surrounding the electrode lead 130. The insulating member 135 may serve to prevent an electrical short circuit between the electrode lead 130 and the case 120. In some examples, the insulating member 135 may prevent an electrical short circuit between the metal layer of the case 120 and the electrode lead 130. The insulating member 135 may be located between the sealing portion 124 of the body 121 and the cover 122. In some examples, the insulating member 135 may be heat-sealed together with the sealing portion 124 and the cover 122 when the sealing portion 124 and the cover 122 are heat-sealed.

[0049] In some examples, the first current collecting tab 111 and the second current collecting tab 112 to which the electrode lead 130 is connected can be folded and stored in the storage portion 123.

[0050] 2a to 2j illustrate a manufacturing process of a secondary battery according to an embodiment of the present invention.

[0051] In the present invention, the coupling relationship between the first and second current collecting tabs 111 and 112 and the electrode lead 130 is the same, and therefore, the following description will focus on the coupling relationship between the first current collecting tab 111 and the electrode lead 130. Therefore, the description of the first current collecting tab 111 can be equally applied to the second current collecting tab 112.

[0052] 2a, the first current collecting tab 111 may be welded to the electrode lead 130 at the end 111b. Here, the end 111b of the first current collecting tab 111 and the electrode lead 130 overlap to form a welding area W, and welding may be performed at the welding area W by a method such as laser welding. In addition, an insulating member 135 may be formed in a region where the electrode lead 130 will later come into contact with the sealing portion 124 of the case 120.

[0053] 2b and 2c, the first current collecting tab 111 may be bent at a bent portion 111a to form a recessed shape, and an adhesive member 113 may be formed at the bent portion 111a. In particular, as shown in FIG. 2c, the bent portion 111a may have a bent surface that is recessed downward so that the uppermost first current collecting tab 111 is positioned at the innermost position, and an adhesive member 113 may be applied to the inside of the bent surface. The adhesive member 113 may allow the shape of the bent portion 111a of the first current collecting tab 111 to be maintained in a bent state. In addition, the adhesive member 113 may be a UV adhesive, for example, an acrylate-based UV adhesive, and its adhesive strength may be increased by UV irradiation, thereby maintaining the shape.

[0054] 2d and 2f show the steps of manufacturing such an adhesive member 113 in sequence.

[0055] Referring to FIG. 2d, with the first current collecting tab 111 bent, the guide 10 having the groove 11 therein may be raised as shown by the arrow to be coupled to the electrode assembly 110. Then, as shown in FIG. 2e, the first current collecting tab 111 may be positioned within the groove 11 of the guide 10, temporarily maintaining the bent state of the first current collecting tab 111. Furthermore, the substantially "U"-shaped bent shape of the first current collecting tab 111 defines a region bent in a first direction in which the first current collecting tab 111 protrudes from the electrode assembly 110, and the guide 10 may similarly define a region bent in a second direction perpendicular to the first direction. Therefore, the bent shape of the first current collecting tab 111 may not be deformed, and a bent portion 111a having a recessed space may be formed inside the bent portion.

[0056] Continuing with reference to FIG. 2e, an adhesive 113 may then be injected into the folded interior of the first current collecting tab 111 through the injection nozzle 20. At this time, the injected UV adhesive may be an acrylate-based UV adhesive, and may have a viscosity of 20,000 to 30,000 cPs (based on 25). The adhesive 113 may be formed up to the bottom end of the welding area W where the first current collecting tab 111 is welded, thereby preventing the substrate tab from lifting in the welding area W of the first current collecting tab 111. As a result of the injection of the adhesive 113, the process shown in FIG. 2c may be performed.

[0057] 2g, as the pusher 30 advances and applies pressure to the bent portion 111a of the first current collecting tab 111, the bent portion 111a may be further flattened. The pusher 30 used here may have a flat end, but as shown in FIG. 2h, the end 31a of the pusher 31 may be convex, or the end 32a of the pusher 32 may be concave. In this case, if the end 31a of the pusher 31 is convex, the bent portion 111a of the first current collecting tab 111 may be concave. Alternatively, if the end 32a of the pusher 32 is concave, the bent portion 111a of the first current collecting tab 111 may be convex. Due to the shape of the bent portion 111a formed to be convex or concave, some areas of the bent portion 111a are pressed relatively less, and a space may be provided in which the adhesive member 113 can gather. Therefore, the adhesive member 113 can be positioned inside the bent portion 111a without flowing out of the first current collecting tab 111.

[0058] 2i, the lamp 40 may irradiate the bent portion 111a of the first current collecting tab 111 with light to cure the adhesive member 113. Thus, the bent inner surfaces of the bent portion 111a may be fixed in a state where they face each other by the adhesive member 113. Furthermore, when the adhesive member 113 has completely cured, the electrode assembly 110 may be provided in a state where the bent portion 111a of the first current collecting tab 111 is finally bent and fixed, as shown in FIG.

[0059] Therefore, the final electrode assembly 110 can increase the space utilization rate of the upper portion where the bent portion 111a of the first current collecting tab 111 is located, and can prevent the first current collecting tab 111 from loosening or floating after bending.

[0060] Hereinafter, a manufacturing process of a secondary battery according to another embodiment of the present invention will be described.

[0061] 3a to 3d illustrate a manufacturing process of a secondary battery according to another embodiment of the present invention.

[0062] 3a, in a manufacturing process of a secondary battery according to another embodiment of the present invention, the electrode assembly 110 may be dipped into a container containing an adhesive member 113, with the bent portion 111a of the first current collecting tab 111 temporarily bent and coupled to the guide 10. That is, the adhesive member 113 may not be injected through a liquid injection nozzle, but may be positioned within the space around the bent portion 111a as the bent portion 111a is dipped into the adhesive member 113.

[0063] 3b, the bent portion 111a of the first current collecting tab 111 may be compressed by applying pressure to the bent portion 111a using the pusher 30. At this time, an adhesive member 113 may be positioned and applied pressure to the inner space of the bent portion 111a, and the adhesive member 113 may be configured to surround the exterior of the bent portion 111a.

[0064] 3c, the adhesive member 113 may then be cured using a lamp 40. The cured adhesive member 113 may also fix the bent portion 111a of the first current collecting tab 111 in a bent state.

[0065] Therefore, the final electrode assembly 110 manufactured using the manufacturing method according to another embodiment of the present invention can also increase the space utilization rate of the upper portion where the bent portion 111a of the first current collecting tab 111 is located, and can prevent the first current collecting tab 111 from loosening or floating after bending.

[0066] Hereinafter, the improved effects of the secondary battery according to an embodiment of the present invention will be further described.

[0067] 4a and 4b are photographs comparing the shape of a secondary battery according to an embodiment of the present invention with a conventional structure.

[0068] First, referring to Figure 4a, in the case of an electrode assembly in which an adhesive member is not formed at the bent portion, it can be seen that the first current collecting tab is spread at an angle of 107.25° or 111.58°. That is, as shown in Figure 4a, it can be seen that the shape of the bent portion is deformed, which can cause the first current collecting tab to loosen, and that the spread of the bent shape of the first current collecting tab reduces the upper utilization rate of the electrode assembly.

[0069] 4b, in the case of the secondary battery according to an embodiment of the present invention, it can be seen that the first current collecting tab 111 is spread at an angle of 81.61° or 85.06°. Therefore, when comparing the structure of FIG. 4b with FIG. 4a, it can be seen that the first current collecting tab 111 remains bent. In other words, as described above, the structure of the secondary battery according to an embodiment of the present invention can prevent the first current collecting tab 111 from loosening or floating, thereby increasing the upper utilization rate of the electrode assembly 110.

[0070] The above description is merely one embodiment for carrying out the secondary battery according to the present invention, and the present invention is not limited to the above embodiment. As claimed in the following claims, it can be said that the technical spirit of the present invention lies within the scope of various modifications that can be made by anyone having ordinary skill in the art to which the invention pertains, without departing from the gist of the present invention. [Explanation of symbols]

[0071] 10: Guide 11: Groove 20: Injection nozzle 30, 31, 32: Pusher 31a, 32a: Termination 40: Lamp 100: Secondary battery 110: Electrode assembly 111: First current collecting tab 111a; Bending part 111b; end 112: Second current collecting tab 112a; Bending part 112b; end 113: Adhesive material 120: Case 121:Main body 122: Cover 123: Storage unit 124: Sealing part 130: Electrode lead 135: Insulating material W: Welding area

Claims

1. an electrode assembly including a current collecting tab having a folded portion formed by folding at least once, the folded end of the current collecting tab protruding from the folded end; a case including a body having a receiving portion for receiving the electrode assembly and a cover for covering the body; an electrode lead electrically connected to an end of the current collecting tab via a welding region and extending to the outside of the case; The folding mechanism further includes an adhesive member formed corresponding to the folding portion, The adhesive member is formed up to a lower end of the welding area where the current collecting tab is welded.

2. The secondary battery according to claim 1 , wherein the adhesive member is formed on an inner surface of the folded portion.

3. The secondary battery of claim 1 , wherein the adhesive member fixes the shape of the bent portion to the outside of the electrode assembly.

4. The secondary battery according to claim 1 , wherein the adhesive member is accommodated in an area formed by folding the folding portion to form a recess.

5. The secondary battery according to claim 1 , wherein the adhesive member is not provided on an end of the current collecting tab where the current collecting tab is connected to an electrode lead.

6. The secondary battery according to claim 5 , wherein the adhesive member is formed to fill the inside of the folded portion and is formed below the end of the current collecting tab.

7. The secondary battery according to claim 1 , wherein the adhesive member is formed on both the inner and outer surfaces of the folded portion of the current collecting tab.

8. The secondary battery according to claim 7 , wherein the adhesive member bonds the folded portion of the current collecting tab to the outer surface of the electrode assembly.

9. The secondary battery according to claim 1 , wherein the adhesive member includes a UV adhesive.

10. The secondary battery according to claim 1 , wherein the adhesive member includes an acrylate-based UV adhesive.

11. providing an electrode assembly having a folded portion formed by at least one fold, the folded end including a current collecting tab protruding therefrom; electrically connecting an electrode lead to an end of the current collecting tab; a step of pouring a liquid into an adhesive member formed corresponding to the bent portion; and curing the adhesive member. a current collecting tab having the bent portion is dipped into a container provided with the adhesive member, and the adhesive member is injected so as to correspond to the bent portion.

12. The method for manufacturing a secondary battery according to claim 11 , wherein the adhesive member is injected into the inner surface of the folded portion through an injection nozzle.

13. The method for manufacturing a secondary battery according to claim 11 , further comprising the step of: using a pusher to apply pressure to the folded portion into which the adhesive member has been poured, thereby tightly fitting the folded portion to the electrode assembly.

14. The method of claim 11, wherein the adhesive member is made of a UV adhesive, and the adhesive member is cured by irradiating light from a lamp.

15. The method of manufacturing a secondary battery according to claim 13 , wherein the pusher has a bulged or dented end that applies pressure.

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