Electrode assembly and secondary battery including the same

Abstract

The present invention relates to an electrode assembly and a secondary battery including the electrode assembly. Since negative electrode tabs and positive electrode tabs are welded to multiple negative electrode uncoated portions and multiple positive electrode uncoated portions of the electrode assembly to serve as current collecting plates, the present invention can prevent roundness reduction, deformation, etc. caused by expansion of a silicon-based negative electrode active material that can be applied for high capacitance, and simultaneously promote high power output and low resistance. To this end, the present invention relates to an electrode assembly, which includes: a positive plate, to which a positive electrode tab is attached; a negative plate, to which a negative electrode tab is attached; and a separator, which is placed between the positive plate and the negative plate, the electrode assembly being wound while the positive plate, the separator and the negative plate are laminated, wherein the positive plate protrudes upward more than the separator and the negative plate to be exposed through the upper surface of the electrode assembly, and the negative plate protrudes downward more than the separator and the positive plate to be exposed through the bottom surface of the electrode assembly, wherein the positive electrode tab extends along the upper surface of the electrode assembly while contacting the positive plate exposed through the upper surface of the electrode assembly, and is welded to the multiple positive plates contacted, and the negative electrode tab extends along the bottom surface of the electrode assembly while contacting the negative plate exposed through the bottom surface of the electrode assembly, and is welded to the multiple negative plates contacted.

Description

Technical Field

[0001] The present invention relates to an electrode assembly and a secondary battery including the electrode assembly. Background Art

[0002] Typically, a secondary battery is manufactured by housing an electrode assembly including a positive plate, a negative plate, and a separator disposed between the two plates with an electrolyte in a housing. Unlike non-rechargeable primary batteries, secondary batteries can be charged and discharged. With the technological development of mobile devices such as mobile phones, laptops, etc. and the increase in the production of mobile devices, the demand for secondary batteries as energy sources has increased dramatically. Recently, secondary batteries have been actively developed as an alternative energy source for fossil fuels used in electric vehicles, hybrid vehicles, etc.

[0003] Currently available secondary batteries include nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, nickel-zinc (Ni-Zn) batteries, lithium secondary batteries, etc. Specifically, lithium secondary batteries produce less memory effect than nickel-based secondary batteries, so that lithium secondary batteries can be freely charged and discharged, and lithium secondary batteries have several advantages including low self-discharge rate and high energy density. Therefore, lithium secondary batteries are attracting more and more attention. Summary of the invention

[0004] Technical issues

[0005] In order to overcome the problems of the prior art, the present invention provides an electrode assembly and a secondary battery including the electrode assembly. Since the negative electrode tab and the positive electrode tab are welded to multiple negative electrode uncoated portions and multiple positive electrode uncoated portions of the electrode assembly to serve as current collecting plates, the present invention can prevent roundness reduction, deformation, etc. caused by expansion of a silicon-based negative electrode active material applied for high capacitance, and simultaneously promote high power output and low resistance.

[0006] Technical Solution

[0007] According to one aspect of the present invention, an electrode assembly is provided, the electrode assembly comprising: a positive plate, to which a positive electrode tab is attached; a negative plate, to which a negative electrode tab is attached; and a separator, which is placed between the positive plate and the negative plate, the electrode assembly being wound while the positive plate, the separator and the negative plate are laminated, wherein the positive plate protrudes upward more than the separator and the negative plate to be exposed through the upper surface of the electrode assembly, and the negative plate protrudes downward more than the separator and the positive plate to be exposed through the bottom surface of the electrode assembly, wherein the positive electrode tab extends along the upper surface of the electrode assembly while contacting the positive plate exposed through the upper surface of the electrode assembly, and is welded to the multiple positive plates contacted, and the negative electrode tab extends along the bottom surface of the electrode assembly while contacting the negative plate exposed through the bottom surface of the electrode assembly, and is welded to the multiple negative plates contacted.

[0008] The positive electrode plate may include: a positive electrode current collector, which is a plate-shaped metal foil; and a positive electrode coating, which covers a first surface and a second surface of the positive electrode current collector, wherein the positive electrode current collector includes a first positive electrode uncoated portion without the positive electrode coating located on the first surface and a second positive electrode uncoated portion without the positive electrode coating located at the top along the length direction on both surfaces of the electrode assembly, wherein the second positive electrode uncoated portion is exposed to the upper surface of the electrode assembly.

[0009] The first positive uncoated portion of the positive electrode plate may be disposed at the center of the first surface of the positive current collecting plate.

[0010] The first positive electrode uncoated portion of the positive electrode plate may be disposed at a winding trailing edge on the first surface of the positive electrode current collecting plate.

[0011] The positive electrode tab may include: a positive electrode fixing portion, which is attached and welded to a first positive electrode uncoated portion located on a first surface of the positive electrode current collecting plate; a positive electrode extension portion, which is bent from a top end of the positive electrode fixing portion and extends along an upper surface of the electrode assembly and then is welded to a second positive electrode uncoated portion; and a positive electrode protruding portion, which is bent from the positive electrode extension portion and extends in a length direction of the electrode assembly and protrudes upward.

[0012] The positive electrode extension portion may include a plurality of positive electrode welding portions laser-welded to the second positive electrode uncoated portion contacting the positive electrode extension portion at the second positive electrode uncoated portion exposed to the upper surface of the electrode assembly.

[0013] The negative electrode plate may include: a negative electrode current collector formed of a plate-shaped metal foil; and a negative electrode coating covering a first surface and a second surface of the negative electrode current collector, wherein the negative electrode current collector includes a first negative electrode uncoated portion without the negative electrode coating located at a winding trailing edge of the first surface of the negative electrode current collector and a second negative electrode uncoated portion without the negative electrode coating located at the bottom along the length direction on both surfaces of the electrode assembly, wherein the second negative electrode uncoated portion is exposed to the bottom surface of the electrode assembly.

[0014] The negative electrode tab may include: a negative electrode fixing portion, a first negative electrode uncoated portion attached and welded to a first surface of the negative electrode current collecting plate; and a negative electrode extending portion, bent from a bottom end of the negative electrode fixing portion and extending along a bottom surface of the electrode assembly, and then welded to a second negative electrode uncoated portion.

[0015] The negative electrode extending portion may include a plurality of negative electrode welding portions laser-welded to the second negative electrode uncoated portion contacting the negative electrode extending portion at the second negative electrode uncoated portion exposed to the bottom surface of the electrode assembly.

[0016] The negative electrode coating may be a silicon-based negative electrode active material.

[0017] The separator may extend downward and protrude more than the positive electrode plate in the length direction of the electrode assembly, and simultaneously extend upward and protrude more than the negative electrode plate in the length direction of the electrode assembly.

[0018] According to another aspect of the present invention, a secondary battery is provided, the secondary battery comprising an electrode assembly, a housing and a cap assembly, the electrode assembly comprising: a positive electrode plate, a positive electrode tab being attached to the positive electrode plate; a negative electrode plate, a negative electrode tab being attached to the negative electrode plate; and a separator, which is interposed between the positive electrode plate and the negative electrode plate and is wound while the positive electrode plate, the separator and the negative electrode plate are laminated, wherein the positive electrode plate protrudes upward more than the separator and the negative electrode plate to be exposed through the upper surface of the electrode assembly, and the negative electrode plate protrudes downward more than the separator and the positive electrode plate to be exposed through the bottom surface of the electrode assembly, wherein the positive electrode tab A positive electrode tab extends along the upper surface of the electrode assembly while contacting the positive electrode plate exposed through the upper surface of the electrode assembly and is welded to the multiple positive electrode plates being contacted, a negative electrode tab extends along the bottom surface of the electrode assembly while contacting the negative electrode plate exposed through the bottom surface of the electrode assembly and is welded to the multiple negative electrode plates being contacted, a shell is provided with an internal space and accommodates the electrode assembly and an electrolyte solution in the internal space, a cover assembly is coupled to the top of the shell and seals the shell, wherein the negative electrode tab welded to the bottom surface of the electrode assembly is welded to the bottom surface of the shell by resistance welding.

[0019] The positive electrode tab may be bent from a region welded to the upper surface of the electrode assembly and extend upward in a length direction of the electrode assembly to then be welded to the cap assembly.

[0020] Technical Effects

[0021] In the electrode assembly according to the present invention and the secondary battery including the electrode assembly, since the negative electrode tab and the positive electrode tab are welded to the multiple negative electrode uncoated portions and the multiple positive electrode uncoated portions of the electrode assembly to serve as current collecting plates, it is possible to prevent roundness reduction, deformation, etc. that may be caused by expansion of the silicon-based negative electrode active material applied for high capacitance, and at the same time, high power output and low resistance can be promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1a , Figure 1b and Figure 1c are a perspective view, an exploded perspective view, and a longitudinal sectional view of a secondary battery according to an embodiment.

[0023] Figure 2a and Figure 2b It is shown Figure 1c Magnified views of portions 2A and 2B.

[0024] Figure 3 Shown in Figure 1a to Figure 1c An example of an exploded perspective view before an electrode assembly in a secondary battery is wound is shown in FIG.

[0025] Figure 4a , Figure 4b and Figure 4c yes Figure 1a to Figure 1c 1 and 2 , which are perspective views, plan views, and rear views of an electrode assembly in a secondary battery shown in FIG.

[0026] Figure 5 Shown in Figure 1a to Figure 1c Another example of an exploded perspective view before the electrode assembly in the secondary battery is wound is shown in FIG. DETAILED DESCRIPTION

[0027] Hereinafter, example embodiments of the present invention will be described in detail. Various embodiments of the present invention can be implemented in many different forms and should not be construed as being limited to the example embodiments set forth herein. On the contrary, these example embodiments of the invention are provided so that the present invention will be thorough and complete, and will convey the inventive concept of the invention to those skilled in the art.

[0028] In addition, in the accompanying drawings, for the sake of brevity and clarity, the size or thickness of various components is exaggerated. The same reference numerals always refer to the same elements. As used herein, the term "and / or" includes any combination and all combinations of one or more of the related listed items. In addition, it will be understood that when element A is referred to as being "connected to" element B, element A can be directly connected to element B, or there can be an intermediate element C and element A and element B are indirectly connected to each other.

[0029] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. It will also be understood that the term "comprising" and / or its variations when used in this specification, indicates the presence of the stated features, quantities, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, components and / or their groups.

[0030] It will be understood that, although the terms first, second, etc. can be used to describe various components, elements, regions, layers and / or parts, these components, elements, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish a component, element, region, layer and / or part from another component, element, region, layer and / or part. Therefore, for example, without departing from the teachings of the present invention, the first component, first element, first region, first layer and / or first part discussed below can be named as the second component, second element, second region, second layer and / or second part.

[0031] For ease of description, spatially relative terms such as "under", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature to another element or feature as shown in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of an element or feature in use or operation in addition to the orientation depicted in the drawings. For example, if an element or feature in a drawing is flipped, an element described as "under" or "beneath" another element or feature would subsequently be positioned as "on" or "above" the other element or feature. Thus, the exemplary term "under" may encompass both above and below orientations.

[0032] Figure 1a , Figure 1b and Figure 1c 1 and 2 are perspective views, exploded perspective views, and longitudinal cross-sectional views of a secondary battery 100 according to an embodiment. Here, the longitudinal cross-section refers to a cross-section obtained by cutting the secondary battery 100 along a length direction.

[0033] like Figure 1a , Figure 1b and Figure 1c As shown in , a secondary battery 100 according to the present invention includes a case 110 , an electrode assembly 120 accommodated in the case 110 , and a cap assembly 130 sealing a top opening of the case 110 .

[0034] The housing 110 includes a circular bottom 111 and a side 112 extending upward from the bottom 111 by a predetermined length. In an embodiment, the secondary battery 100 is shown as a cylindrical secondary battery, but the present invention is not limited thereto. For example, a prismatic or pouch-type secondary battery may also be applied to the present invention. During the manufacture of the secondary battery 100, the top of the housing 110 is in an open state. Therefore, the electrode assembly 120 may be inserted into the housing 110 together with the electrolyte solution for assembling the secondary battery 100. The housing 110 may be made of steel, steel alloy, aluminum, aluminum alloy, or its equivalent, but the present invention is not limited thereto. In addition, in order to prevent or substantially prevent the electrode assembly 120 from deviating to the outside, an inwardly recessed beading part 113 may be formed at the bottom of the cap assembly 130, and an inwardly bent crimping part 114 may be formed at the top of the cap assembly 130.

[0035] The electrode assembly 120 is accommodated in the housing 110 together with an electrolyte solution. In an embodiment, the electrolyte solution may be an organic solution containing a salt that is injected to enable lithium ions to move between the positive electrode plate and the negative electrode plate of the electrode assembly 120. The electrolyte solution may include a non-aqueous organic electrolyte solution that is a mixture of a lithium salt (such as LiPF6, LiBF4, or LiClO4) and a high-purity organic solvent, but embodiments of the present invention are not limited thereto.

[0036] The electrode assembly 120 includes a negative electrode plate 121 coated with a negative active material, a positive electrode plate 122 coated with a positive active material, and a separator 123, which is interposed between the negative electrode plate 121 and the positive electrode plate 122 and allows only lithium ions to move between the negative electrode plate 121 and the positive electrode plate 122 while preventing or substantially preventing an electrical short circuit between the negative electrode plate 121 and the positive electrode plate 122. The electrode assembly 120 is formed into a substantially cylindrical shape by laminating the negative electrode plate 121, the positive electrode plate 122, and the separator 123 and then winding them. In addition, a negative electrode tab 124 protruding downward by a predetermined length and extending may be attached to the negative electrode plate 121, and a positive electrode tab 125 protruding upward by a predetermined length and extending may be attached to the positive electrode plate 122, or vice versa.

[0037] Next, refer to Figure 2a and Figure 2b , showing Figure 1c 2A and 2B of the enlarged view. Figure 3 , showing that in Figure 1a to Figure 1c An example of an exploded perspective view of an electrode assembly in a secondary battery before being wound is shown in FIG. Figure 4a , Figure 4b and Figure 4c , showing Figure 1a to Figure 1cThe perspective view, plan view and rear view of the electrode assembly in the secondary battery shown in FIG. Figure 2a , Figure 2b , Figure 3 , Figure 4a , Figure 4b and Figure 4c Configurations of an electrode assembly and a secondary battery according to an embodiment of the present invention are further described in detail.

[0038] First, the negative electrode plate 121 of the electrode assembly 120 includes a negative electrode coating 121b formed by coating a silicon-based negative electrode active material on both surfaces of a negative electrode current collector 121a formed of a copper (Cu) or nickel (Ni) plate-shaped metal foil. The negative electrode plate 121 has a negative electrode tab 124 attached to a first surface of the negative electrode current collector 121a. The negative electrode tab 124 includes a negative electrode fixing portion 124a partially welded and attached to the negative electrode current collector 121a and a negative electrode extension portion 124b protruding downward by a predetermined length in the length direction of the electrode assembly 120.

[0039] The negative electrode tab 124 may be attached to the region of the winding trailing edge (i.e., winding end) x2 at the negative current collecting plate 121a. In an embodiment, the winding trailing edge x2 may be positioned at the outermost portion of the electrode assembly 120, and the winding leading edge (i.e., winding front end) x1 may be positioned approximately at the center of the electrode assembly 120. That is, after laminating the negative electrode plate 121, the separator 123, and the positive electrode plate 122, the electrode assembly 120 may be wound along the winding direction x from the winding leading edge x1 into a cylindrical shape.

[0040] In addition, the negative electrode tab 124 is attached to the region of the winding trailing edge x2 of the negative current collecting plate 121a. In addition, the negative electrode tab 124 is attached to the first surface of the negative current collecting plate 121a at the region of the winding trailing edge x2, thereby being spaced apart from the negative electrode coating 121b. A first negative electrode uncoated portion 121c without a negative electrode coating 121b is provided at the negative current collecting plate 121a to which the negative electrode tab 124 is attached. In addition, the negative current collecting plate 121a also includes a first negative electrode uncoated portion 121c without a negative electrode coating 121b on a second surface opposite to the first surface to which the negative electrode tab 124 is attached, in a region corresponding to the negative electrode tab 124 and in a region corresponding to the region where the first negative electrode uncoated portion 121c is provided.

[0041] In addition, the negative electrode current collector 121a may also include a second negative electrode uncoated portion 121d without a negative electrode coating 121b at the bottom along the length direction y on both surfaces of the negative electrode current collector 121a. In addition, the second negative electrode uncoated portion 121d may protrude downward from the electrode assembly 120 more than the positive electrode plate 122 and the separator 123. That is, the electrode assembly 120 may position the second negative electrode uncoated portion 121d on its bottom surface 120y. In addition, the separator 123 may extend downward and protrude more in the length direction y of the electrode assembly 120 than the positive electrode plate 122, thereby electrically insulating the negative electrode plate 121 and the positive electrode plate 122 from each other. In addition, the separator 123 of the electrode assembly 120 may be used to prevent the positive electrode plate 122 from electrically contacting the bottom 111 of the housing 110.

[0042] In addition, the negative extension portion 124b of the negative electrode tab 124 protruding downward from the bottom surface 120y of the electrode assembly 120 may be welded to the second negative electrode uncoated portion 121d positioned on the bottom surface of the electrode assembly 120. The negative extension portion 124b of the negative electrode tab 124 may be bent from the negative electrode fixing portion 124a and then extended while contacting the bottom surface 120y of the electrode assembly 120, and thus may include a negative electrode welding portion 124x welded to a plurality of second negative electrode uncoated portions 121d by laser welding. That is, the negative electrode tab 124 may be used as a negative current collecting plate by welding to a plurality of negative electrode welding portions 124x of the second negative electrode uncoated portion 121d. The negative electrode tab 124 may be made of copper or nickel, but embodiments of the present invention are not limited thereto.

[0043] The positive electrode plate 122 includes a positive electrode coating 122b formed by coating an active material such as a transition metal oxide on both surfaces of a positive electrode current collecting plate 122a formed of a metal foil in the form of an aluminum (Al) plate. The positive electrode plate 122 has a positive electrode terminal tab 125 attached to a first surface of the positive electrode current collecting plate 122a. The positive electrode terminal tab 125 includes a positive electrode fixing portion 125a partially welded and attached to the positive electrode current collecting plate 122a and a positive electrode extension portion 125b protruding upward by a predetermined length in the length direction y of the electrode assembly 120.

[0044] The positive electrode tab 125 may be attached to an area at the positive current collector 122a that is approximately located at the center based on the winding direction x. In addition, the positive electrode tab 125 is attached to the first surface at the center of the positive current collector 122a to be spaced apart from the positive electrode coating 122b. A first positive electrode uncoated portion 122c that does not have a positive electrode coating 122b is disposed at the positive current collector 122a to which the positive electrode tab 125 is attached. In addition, the positive current collector 122a also includes a first negative electrode uncoated portion 122c that does not have a positive electrode coating 122b on a second surface that is opposite to the first surface to which the positive electrode tab 125 is attached, in an area corresponding to the positive electrode tab 125 and in an area corresponding to the area where the first positive electrode uncoated portion 122c is disposed.

[0045] In addition, the positive current collector plate 122a may also include a second positive uncoated portion 122d without a positive electrode coating 122b at the top along the length direction y on both surfaces of the electrode assembly 120. In addition, the second positive uncoated portion 122d may protrude more upward from the electrode assembly 120 than the negative plate 121 and the separator 123. That is, the electrode assembly 120 may have the second positive uncoated portion 122d located on its upper surface 120x. In addition, the separator 123 of the electrode assembly 120 may extend upward and protrude more in the length direction y of the electrode assembly 120 than the negative plate 121, thereby maintaining electrical insulation between the negative plate 121 and the positive plate 122.

[0046] In addition, the positive extension portion 125b of the positive electrode tab 125 protruding upward from the upper surface 120x of the electrode assembly 120 may be welded to the second positive electrode non-coated portion 122d positioned on the upper surface of the electrode assembly 120. The positive extension portion 125b of the positive electrode tab 125 may be bent from the positive electrode fixing portion 125a and then extended while contacting the upper surface 120x of the electrode assembly 120, and thus may include a positive electrode welding portion 125x welded to the plurality of second positive electrode non-coated portions 122d by laser welding. That is, the positive electrode tab 125 may be used as a positive current collecting plate by the positive electrode welding portion 125x welded to the plurality of second positive electrode non-coated portions 122d.

[0047] In addition, the positive electrode tab 125 may further include a positive electrode protruding portion 125c bent from the end of the positive electrode extension portion 125b and protruding and extending upward from the electrode assembly 120. That is, the positive electrode tab 125 includes a positive electrode fixing portion 125a welded to the first positive electrode non-coated portion 122c of the positive current collecting plate 122a, a positive electrode protruding portion 125c protruding and extending upward from the upper surface 120x of the electrode assembly 120, and a positive electrode extension portion 125b connecting the positive electrode fixing portion 125a and the positive electrode protruding portion 125c and welded to the upper surface 120x of the electrode assembly 120. In addition, the positive electrode protruding portion 125c of the positive electrode tab 125 may be bent from the positive electrode extension portion 125b to be spaced apart from the upper surface 120x of the electrode assembly 120, and then may extend horizontally so as to be then welded to the cap assembly 130. The positive electrode tab 125 may be made of aluminum, but the embodiments of the present invention are not limited thereto.

[0048] In addition, the negative extension portion 124b of the negative electrode tab 124 of the electrode assembly 120 may be welded to the bottom 111 of the case 110. In an embodiment, after the electrode assembly 120 is inserted into the case 110, the negative extension portion 124b of the negative electrode tab 124 may be welded to the bottom 111 of the case 110 by resistance welding. Therefore, the case 110 may be used as a negative electrode. Conversely, the positive electrode tab 125 may be welded to the bottom 111 of the case 110 by resistance welding. In this case, the case 110 may be used as a positive electrode.

[0049] In addition, an insulating plate 126 may be placed between the electrode assembly 120 and the cap assembly 130, the insulating plate 126 being coupled to the housing 110 and having a first hole 126a at its center and a plurality of second holes 126b at the outside of the first hole 126a. That is, the insulating plate 126 may be positioned on the electrode assembly 120. The insulating plate 126 may prevent the electrode assembly 120 from electrically contacting the cap assembly 130. Specifically, the insulating plate 126 may be used to prevent the negative plate 121 of the electrode assembly 120 from electrically contacting the cap assembly 130. In an embodiment, the first hole 126a may enable a large amount of gas generated due to an abnormality of the secondary battery to move quickly toward the cap assembly 130, and some of the plurality of second holes 126b through which the positive electrode tab 125 may pass may enable the positive electrode tab 125 to be welded to the cap assembly 130. In addition, the second hole 126b may enable the electrolyte solution to flow quickly into the electrode assembly 120 during the injection of the electrolyte solution. The electrolyte solution may function as a moving medium of lithium ions generated by electrochemical reactions occurring at the positive and negative electrode plates of the secondary battery 100 during charge and discharge.

[0050] The cover assembly 130 includes an upper cover 131 having a plurality of through holes 131d formed therein, a safety plate 133 installed under the upper cover 131, a connecting ring 135 installed under the safety plate 133, a lower cover 136 coupled to the connecting ring 135 and having a first through hole 136a and a second through hole 136b formed therein, a sub-plate 137 fixed to the bottom of the lower cover 136 and welded and electrically connected to the positive electrode tab 125, and an insulating gasket 138 for insulating the upper cover 131, the safety plate 133, the connecting ring 135 and the lower cover 136 from the side 112 of the shell.

[0051] In an embodiment, the insulating gasket 138 is compressed between the curling portion 113 and the crimping portion 114 substantially formed at the side portion 111 of the housing 110. In addition, the through hole 131d formed in the upper cover 131 and the second through hole 136b formed in the lower cover 136 may function to discharge internal gas to the outside when abnormal internal pressure is generated in the housing 110. The safety plate 133 is first reversed upward by the internal pressure to be electrically disconnected from the sub-plate 137, and then ruptures, thereby releasing the internal gas to the outside.

[0052] In the electrode assembly and the secondary battery 100 including the electrode assembly, since the negative electrode tab 124 and the positive electrode tab 125 are welded to the plurality of second negative electrode uncoated portions 121d and the plurality of second positive electrode uncoated portions 122d of the electrode assembly 120 to serve as current collecting plates, the present invention can prevent roundness reduction, deformation, etc. caused by expansion of the silicon-based negative electrode active material applied for high capacitance, and simultaneously promote high power output and low resistance.

[0053] In addition, refer to Figure 5 , showing that in Figure 1a to Figure 1c Another example of an exploded perspective view of an electrode assembly in a secondary battery before being wound is shown in FIG. 1 . Hereinafter, the configuration of an electrode assembly and a secondary battery according to the present invention will be further described in detail. The electrode assembly 220 is similar to the negative electrode plate 121, the separator 123, and the negative electrode tab 124 in terms of their structures. Figure 3 The electrode assembly 220 is the same as the electrode assembly 120 shown in FIG. Figure 1a , Figure 1b , Figure 1c , Figure 2a and Figure 2b The connection relationship between the housing 110 and the cover assembly 130 shown in FIG. Figure 3 The electrode assembly 120 shown in FIG.

[0054] Therefore, the following description will focus on the positive electrode plate 222 and the positive electrode tab 225 of the electrode assembly 220 that are different from the corresponding components of the electrode assembly 120. In addition, the perspective view, the plan view, and the rear view after the electrode assembly 220 is wound may be the same as Figure 4a , Figure 4b and Figure 4c The perspective view, plan view, and rear view of the electrode assembly 120 shown in FIG. 1 are the same.

[0055] However, the electrode assembly 220 and Figure 1a , Figure 1b , Figure 1c , Figure 2a , Figure 2b , Figure 4a , Figure 4b and Figure 4c The electrode assembly 120 shown in FIG. 1 is different in that a positive electrode tab 225 protrudes upward from a rear edge based on a winding direction at the electrode assembly 220 .

[0056] The positive electrode plate 222 includes a positive electrode coating 222b formed by coating an active material including a transition metal oxide on both surfaces of a positive electrode current collecting plate 222a formed of a plate-shaped metal foil made of aluminum (Al). The positive electrode plate 222 has a positive electrode terminal tab 225 attached to a first surface of the positive electrode current collecting plate 222a. The positive electrode terminal tab 225 includes a positive electrode fixing portion partially welded and attached to the positive electrode current collecting plate 222a and a positive electrode extension portion protruding upward by a predetermined length along the length direction y of the electrode assembly 220.

[0057] The positive electrode tab 225 may be attached to the area of ​​the winding trailing edge x2 at the positive current collecting plate 222a. Here, the winding trailing edge x2 may be positioned at the outermost portion of the electrode assembly 220, and the winding leading edge x1 may be positioned approximately at the center of the electrode assembly 220. That is, after laminating the negative electrode plate 121, the separator 123, and the positive electrode plate 222, the electrode assembly 220 may be wound along the winding direction x from the winding leading edge x1 into a cylindrical shape.

[0058] In addition, the positive electrode tab 225 is attached to the first surface of the winding trailing edge x2 of the positive current collecting plate 222a to be spaced apart from the positive electrode coating 222b. In addition, a first positive electrode uncoated portion 222c without the positive electrode coating 222b is provided on the positive current collecting plate 222a to which the positive electrode tab 225 is attached. In addition, the positive current collecting plate 222a also includes a first negative electrode uncoated portion 222c without the positive electrode coating 222b on a second surface opposite to the first surface to which the positive electrode tab 225 is attached, in an area corresponding to the positive electrode tab 225 and in an area corresponding to the area where the first positive electrode uncoated portion 222c is provided.

[0059] In addition, the positive current collector plate 222a also includes a second positive electrode uncoated portion 222d without a positive electrode coating 222b at the top along the length direction y on both surfaces of the electrode assembly 220. In addition, the second positive electrode uncoated portion 222d can protrude more upward from the electrode assembly 220 than the negative electrode plate 121 and the separator 123. That is, the electrode assembly 220 can have the second positive electrode uncoated portion 222d located on its upper surface. In addition, the separator 123 extends upward and protrudes more in the length direction y of the electrode assembly 220 than the negative electrode plate 121, thereby maintaining electrical insulation between the negative electrode plate 121 and the positive electrode plate 222.

[0060] The positive electrode tab 225 protruding upward from the upper surface of the electrode assembly 220 may be welded to the second positive electrode uncoated portion 222d positioned on the upper surface of the electrode assembly 220. The positive electrode tab 225 may extend while contacting the upper surface of the electrode assembly 220, and then be welded to the plurality of second positive electrode uncoated portions 222d by laser welding. That is, the positive electrode tab 225 may be welded to the plurality of second positive electrode uncoated portions 222d, and thus may serve as a positive current collecting plate.

[0061] In the electrode assembly 220 and the secondary battery 100 including the electrode assembly 220, since the negative electrode tab 124 and the positive electrode tab 225 are welded to the plurality of second negative electrode uncoated portions 121d and the plurality of second positive electrode uncoated portions 222d of the electrode assembly 220 to serve as current collecting plates, the present invention can prevent roundness reduction, deformation, etc. caused by expansion of the silicon-based negative electrode active material applied for high capacitance, and simultaneously promote high power output and low resistance.

[0062] Although the electrode assembly according to the present invention and the secondary battery including the electrode assembly have been specifically shown and described with reference to some exemplary embodiments of the present invention, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as set forth in the following claims.

[0063] Industrial availability

[0064] The present invention relates to an electrode assembly and a secondary battery including the electrode assembly.

Claims

1. An electrode assembly, comprising: a positive plate to which a positive terminal tab is attached; a negative plate to which a negative electrode tab is attached; as well as The separator is placed between the positive electrode plate and the negative electrode plate, and the electrode assembly is wound while the positive electrode plate, the separator and the negative electrode plate are laminated. wherein the positive electrode plate protrudes upward more than the separator and the negative electrode plate to be exposed through the upper surface of the electrode assembly, and the negative electrode plate protrudes downward more than the separator and the positive electrode plate to be exposed through the bottom surface of the electrode assembly, Wherein, the positive electrode plate comprises: A positive electrode current collector, which is a plate-shaped metal foil; and a positive electrode coating covering a first surface and a second surface of a positive electrode current collector, wherein the positive electrode current collector comprises a first positive electrode uncoated portion without the positive electrode coating on the first surface and a second positive electrode uncoated portion without the positive electrode coating at the top along the length direction on both surfaces of the electrode assembly, wherein the second positive electrode uncoated portion is exposed to the upper surface of the electrode assembly, and Among them, the positive electrode terminal piece includes: a positive electrode fixing portion attached and welded to the first positive electrode uncoated portion; and a positive electrode extending portion, which is bent from a top end of the positive electrode fixing portion and extends along an upper surface of the electrode assembly, and then is welded to the second positive electrode uncoated portion, and The negative electrode tab extends along the bottom surface of the electrode assembly while contacting the negative electrode plates exposed through the bottom surface of the electrode assembly, and is welded to the contacted plurality of negative electrode plates.

2. The electrode assembly according to claim 1, wherein: The first positive electrode uncoated portion of the positive electrode plate is disposed at the center of the first surface of the positive electrode current collecting plate.

3. The electrode assembly according to claim 1, wherein: The first positive electrode uncoated portion of the positive electrode plate is disposed at a winding trailing edge on the first surface of the positive electrode current collecting plate.

4. The electrode assembly according to claim 1, wherein: The positive terminal lug also includes: The positive electrode protruding portion is bent from the positive electrode extending portion and extends in the length direction of the electrode assembly and protrudes upward.

5. The electrode assembly according to claim 4, wherein: The positive electrode extension portion includes a plurality of positive electrode welding portions laser-welded to the second positive electrode uncoated portion contacting the positive electrode extension portion at the second positive electrode uncoated portion exposed to the upper surface of the electrode assembly.

6. The electrode assembly according to claim 1, wherein: The negative electrode plate comprises: a negative electrode current collecting plate formed of a plate-shaped metal foil; and A negative electrode coating covers the first surface and the second surface of the negative electrode current collector, The negative electrode current collector plate includes a first negative electrode uncoated portion without a negative electrode coating located at the winding trailing edge of the first surface of the negative electrode current collector plate, and a second negative electrode uncoated portion without a negative electrode coating located at the bottom along the length direction on both surfaces of the electrode assembly, wherein the second negative electrode uncoated portion is exposed to the bottom surface of the electrode assembly.

7. The electrode assembly according to claim 6, wherein: The negative electrode terminal piece comprises: a negative electrode fixing portion attached and welded to the first negative electrode uncoated portion of the first surface of the negative electrode current collecting plate; and The negative electrode extending portion, which is bent from the bottom end of the negative electrode fixing portion and extends along the bottom surface of the electrode assembly, is then welded to the second negative electrode uncoated portion.

8. The electrode assembly according to claim 7, wherein: The negative electrode extending portion includes a plurality of negative electrode welding portions laser-welded to the second negative electrode uncoated portion contacting the negative electrode extending portion at the second negative electrode uncoated portion exposed to the bottom surface of the electrode assembly.

9. The electrode assembly according to claim 6, wherein: The negative electrode coating is a silicon-based negative electrode active material.

10. The electrode assembly according to claim 1, wherein: The separator extends downward and protrudes more than the positive electrode plate in the length direction of the electrode assembly, and extends upward and protrudes more than the negative electrode plate in the length direction of the electrode assembly.

11. A secondary battery, comprising: The electrode assembly according to any one of claims 1 to 10; a case provided with an internal space and accommodating the electrode assembly and the electrolyte solution in the internal space; and a cover assembly, coupled to the top of the housing and sealing the housing, Herein, the negative electrode tab welded to the bottom surface of the electrode assembly is welded to the bottom surface of the case by resistance welding.

12. The secondary battery according to claim 11, wherein The positive electrode tab is bent and extends upward in the length direction of the electrode assembly from an area welded to the upper surface of the electrode assembly, and then is welded to the cap assembly.

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