Electrode assembly and rechargeable battery including same

Abstract

An electrode assembly and a rechargeable battery including same are disclosed. The electrode assembly according to one embodiment comprises a first electrode plate, a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate, and a first reinforcing member provided on the outer surface of the outermost one from among the first electrode plate and the second electrode plate, wherein the first reinforcing member is a metal plate.

Description

Electrode assembly and secondary battery including the same

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

[0002] Rechargeable batteries are batteries that can be charged and discharged, unlike primary batteries that cannot be recharged. Low-capacity batteries with one electrode assembly packaged in a pack form are used in small portable electronic devices such as mobile phones and camcorders, and large-capacity batteries with dozens of electrode assemblies connected are widely used as power sources for driving motors in electric scooters, hybrid cars, and electric vehicles.

[0003] Secondary batteries are manufactured in various shapes, among which pouch batteries include an electrode assembly formed by interposing a separator, which is an insulator, between a positive and negative electrode plate, and a thin, flexible pouch in which the electrode assembly is embedded. The pouch accommodates the electrode assembly within its inner space.

[0004] Secondary battery electrode assemblies are broadly categorized into winding and stacking types based on their structure. The stacking type offers superior structural stability and space utilization, making it widely used in small, medium, and large-sized batteries. To maximize internal space utilization within secondary batteries, the outermost layer of the electrode assembly typically features a half-cathode configuration.

[0005] However, since the active material is coated on only one side of the current collector of the single-sided cathode, this is relatively more likely to cause curling and warping compared to a double-sided cathode (full cathode) in which the active material is coated on both sides of the current collector. This necessitates the use of a substrate that is twice as thick as the substrate of the double-sided cathode. Furthermore, there is a problem in that the warping generated in the single-sided cathode causes interfacial unevenness, resulting in performance degradation during repeated charging and discharging.

[0006] The present invention is intended to overcome the above-described conventional problems, and an object of the present invention is to provide an electrode assembly capable of improving the rigidity of the outermost part of the electrode assembly and a secondary battery including the same.

[0007] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0008] An electrode assembly according to one embodiment of the present invention for solving the above technical problem includes a first electrode plate and a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate, and a first reinforcing member installed on the outer surface of one of the first electrode plates and the second electrode plate, wherein the first reinforcing member is a metal plate.

[0009] The electrode assembly further includes a second reinforcing member surrounding the exterior of the first reinforcing member, wherein the second reinforcing member may be a polymer.

[0010] The second reinforcing member may be formed to have a relatively larger width than the first reinforcing member so as to surround the first reinforcing member.

[0011] The polymer may be a mixture of ethylene-vinyl acetate copolymer (EVA), linear low density polyethylene (LLDPE), and talc.

[0012] Based on the weight of the polymer, the ethylene vinyl acetate copolymer may be 55 to 60 wt%, the linear low-density polyethylene may be 20 to 25 wt%, and the talc may be 15 to 25 wt%.

[0013] The thickness of the second reinforcing member may be within a range of 3% to 5% of the overall thickness of the electrode assembly.

[0014] The above first reinforcing member may be formed to have a size relatively smaller than one of the first electrode plate and the second electrode plate located at the outermost end.

[0015] The above first reinforcing member may be formed to have a size corresponding to one of the first electrode plates and the second electrode plates located at the outermost end.

[0016] The above first reinforcing member may be a thin film made of stainless steel having an adhesive layer on one surface.

[0017] The first reinforcing member may be formed so that its thickness decreases from one end adjacent to the first electrode substrate tab of the first electrode plate and the second electrode substrate tab of the second electrode plate to the other end.

[0018] The thickness of the first reinforcing member may be within a range of 3% to 5% of the overall thickness of the electrode assembly.

[0019] An electrode assembly according to one embodiment of the present invention includes a first electrode plate and a second electrode plate, a separator interposed between the first electrode plate and the second electrode plate, and a second reinforcing member installed on an outer surface of one of the first and second electrode plates located at the outermost end, wherein the second reinforcing member is made of a polymer.

[0020] The polymer may be a mixture of ethylene-vinyl acetate copolymer (EVA), linear low density polyethylene (LLDPE), and talc.

[0021] Based on the weight of the polymer, the ethylene vinyl acetate copolymer may be 55 to 60 wt%, the linear low-density polyethylene may be 20 to 25 wt%, and the talc may be 15 to 25 wt%.

[0022] The thickness of the second reinforcing member may be within a range of 3% to 5% of the overall thickness of the electrode assembly.

[0023] A secondary battery according to one embodiment of the present invention includes an electrode assembly and a case accommodating the electrode assembly.

[0024] According to the present invention, the electrode assembly can prevent the occurrence of warping and curling, thereby preventing interfacial unevenness caused by warping and resulting performance deterioration during repeated charging and discharging. Accordingly, the lifespan of the secondary battery can be improved.

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0026] FIG. 1 is a perspective view illustrating an electrode assembly according to one embodiment of the present invention housed in a case.

[0027] Fig. 2 is a perspective view showing only the electrode assembly extracted from Fig. 1.

[0028] Fig. 3 is a cross-sectional view of the first reinforcing member of Fig. 2 taken along line A-A'.

[0029] Figure 4 is a drawing showing a modified example of the first reinforcing member.

[0030] FIG. 5 is a perspective view illustrating a process of creating a second reinforcing member in an electrode assembly according to another embodiment of the present invention.

[0031] FIG. 6 is a perspective view illustrating an electrode assembly according to another embodiment of the present invention.

[0032] FIG. 7 is a perspective view illustrating a process of creating a second reinforcing member on a first reinforcing member in an electrode assembly according to another embodiment of the present invention.

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0034] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0035] Additionally, to facilitate understanding of the invention, the attached drawings are not drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0036] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0037] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0038] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0039] Any configuration being placed “on top (or bottom)” of a component or “on top (or bottom)” of a component may mean not only that any configuration is placed in contact with the top (or bottom) of the component, but also that other configurations may be interposed between the component and any configuration placed on (or under) the component.

[0040] Additionally, when a component is described as being “on,” “connected to,” or “coupled to” another component, it should be understood that the components may be directly connected or coupled to one another, but that other components may also be “interposed” between the components, or that each component may be “connected,” “coupled,” or “connected” through other components.

[0041] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, the use of "may" when describing embodiments of the present disclosure refers to "one or more embodiments of the present disclosure." Expressions such as "one or more" and "one or more" preceding a list of elements modify the list as a whole and do not modify individual elements in the list.

[0042] When reference is made throughout the specification to “A and / or B,” this means A, B, or A and B, unless otherwise stated, and when reference is made to “C to D,” this means C or more and D or less, unless otherwise stated.

[0043] When phrases such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group A, B, and C," or "at least one selected from A, B, and C," are used to specify a list of elements A, B, and C, the phrases can refer to any suitable combination.

[0044] The term "use" may be considered synonymous with the term "utilize." As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation rather than degrees, and are intended to take into account inherent variations in measured or calculated values ​​that would be recognized by those skilled in the art.

[0045] Although terms such as first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could also be termed a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0046] For ease of description, spatially relative terms such as "beneath," "below," "lower," "above," "upper," and the like may be used herein to describe the relationship of one element or feature to another element(s) or feature(s) as depicted in the drawings. It will be understood that spatially relative positions encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the drawings is turned over, an element described as "beneath" or "lower" another element would be understood to be "above" or "upper" the other element. Thus, the term "beneath" can encompass both the above and below orientations.

[0047] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0048] Hereinafter, before describing an electrode assembly according to an embodiment of the present invention with reference to the attached drawings, a secondary battery including the electrode assembly will be described in detail.

[0049] FIG. 1 is a perspective view illustrating an electrode assembly according to an embodiment of the present invention housed in a case, and FIG. 2 is a perspective view illustrating only the electrode assembly extracted from FIG. 1.

[0050] As shown in FIGS. 1 and 2, the secondary battery (10) may include an electrode assembly (100A) and a case (200).

[0051] An electrode assembly (100A) may include a first electrode plate (110), a second electrode plate (120), and a separator (130). This electrode assembly (100A) may be formed by arranging a plurality of laminates including the first electrode plate (110), the second electrode plate (120), and the separator (130) and then winding or repeatedly laminating them.

[0052] For example, the electrode assembly (100A) may be of the wound jelly-roll type. Alternatively, the electrode assembly (100A) may also be of the stacking type, in which the laminates are arranged to be stacked in multiple layers. The present invention will be described with the electrode assembly (100A) of the stacking type as an example.

[0053] Meanwhile, the manufacturing process of a stacking type electrode assembly (100A) generally involves a first stacking process and a second process.

[0054] In the first lamination process, a double-sided cathode (Full Cathode) and a double-sided anode (Full Anode) which are the second electrode plates (120) can be laminated, excluding the outermost first electrode plate (110A) among the plurality of first electrode plates (110A, 110B).

[0055] In the secondary lamination process, a half cathode may be laminated on at least one of the outermost sides based on the lamination direction. Here, the half cathode may be the outermost first electrode plate (110A) among the first electrode plates (110).

[0056] For convenience, FIG. 2 illustrates an electrode assembly (100A) in which a cross-sectional cathode is laminated on both the upper outermost surface and the lower outermost surface of the electrode assembly (100A), but it may also be possible for a cross-sectional cathode to be laminated only on the upper outermost surface of the electrode assembly (100A) and a cross-sectional anode to be laminated on the lower outermost surface.

[0057] Here, the double-sided cathode and double-sided anode are those in which the active material is applied to both sides of the substrate, while the single-sided cathode is those in which the active material is applied to only one side of the substrate. Detailed descriptions of such double-sided cathodes, double-sided anodes, and single-sided cathodes are omitted.

[0058] Meanwhile, the first electrode plate (110) and the second electrode plate (120) as described above each include an electrode current collector and an electrode substrate tab (111, 121) extending outward from a portion of the electrode current collector.

[0059] The first electrode substrate tab (111) includes a first electrode current collector (not shown) and a first electrode substrate tab (111) extending outward from a portion of the first electrode current collector. There may be a plurality of first electrode plates (110), and the plurality of first electrode substrate tabs (111) may be joined to each other by a welding method. For example, a plurality of first electrode substrate tabs (111) may be joined together by a welding method such as laser welding, resistance welding, or ultrasonic welding.

[0060] The second electrode plate (120) includes a second electrode current collector (not shown) and a second electrode substrate tab (121) extending outward from a portion of the second electrode current collector. When the electrode assembly (100A) is of a laminated type, the first electrode plate (110) and the second electrode plate (120) may be laminated alternately with a separator (130) interposed therebetween.

[0061] At this time, the second electrode plate (120) may be multiple, like the first electrode plate (110), and the second electrode substrate tabs (121) may also be multiple. The multiple second electrode substrate tabs (121) may be joined to each other by welding as described in the first electrode substrate tab (111), but may also be joined with an adhesive material.

[0062] Meanwhile, the second electrode plate (120) may be a negative electrode, and the first electrode plate (110) may be a positive electrode, but the opposite may also be true. The first electrode plate (110) and the second electrode plate (120) may be electrically connected to the outside of the secondary battery (10) through the strip terminal (160). In addition, an insulating tape (170) may be attached to a portion of the strip terminal (160) that comes into contact with the case (200). The insulating tape (170) may prevent the strip terminal (160) and the case (200) from being electrically connected.

[0063] For convenience of explanation, the following description will be limited to the first electrode plate (110) being the positive electrode and the second electrode plate (120) being the negative electrode.

[0064] More specifically, the first electrode plate (110), which is the positive electrode, may be a first electrode current collector made of a metal foil such as aluminum or an aluminum alloy, to which a first electrode active material such as a transition metal oxide is applied. The first electrode substrate tab (111) is formed integrally with the first electrode current collector, and as described above, may extend outward from a portion of the first electrode plate (110).

[0065] In addition, the first electrode substrate tab (111) may be positioned so as not to overlap with the second electrode substrate tab (121). For example, based on the direction illustrated in FIG. 2, all of the substrate tabs positioned on the right side may be first electrode substrate tabs (111).

[0066] The first electrode substrate tabs (111) may be arranged to be spaced apart from the second electrode substrate tabs (121). In this way, since a plurality of first electrode substrate tabs (111) are arranged, the first electrode substrate tabs (111) are also defined as multi-taps. The first electrode substrate tabs (111) may serve as a path for current flow between the first electrode current collector and the strip terminal (160).

[0067] The second electrode plate (120), which is the negative electrode, can be formed by applying a second electrode active material, such as graphite or carbon, to a second electrode current collector formed of a metal foil, such as copper, copper alloy, nickel, or nickel alloy.

[0068] A separator (130) may be interposed between the first electrode plate (110) and the second electrode plate (120). The separator (130) prevents short circuiting between the first electrode plate (110) and the second electrode plate (120) and enables movement of lithium ions. To this end, the separator (130) may be formed to have a size relatively larger than the first electrode current collector and the second electrode current collector. In addition, the first electrode current collector and the second electrode current collector described above may have the same size.

[0069] The material of the separator (130) may be, for example, made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene, but is not limited thereto.

[0070] Such a separator (130) may be cut into unit lengths and placed between the first electrode plate (110) and the second electrode plate (120), or a single separator (130) in a ribbon shape may be placed in a zigzag shape between the first electrode plate (110) and the second electrode plate (120). Alternatively, the separator (130) may be installed to be wound in one direction between the first electrode plate (110) and the second electrode plate (120). Although the arrangement of the separator (130) is not limited to a specific form, in this embodiment, the description will be limited to the case where the separator (130) is cut into unit lengths and placed between the first electrode plate (110) and the second electrode plate (120).

[0071] The case (200) can accommodate an electrode assembly (100A). The above-described electrode assembly (100A) is accommodated in the case (200) together with an electrolyte.

[0072] The case (200) as described above may be any one of a pouch type, a cylindrical type, and a square type. The pouch type case (200) may be manufactured by bending plate-shaped outer materials so that they face each other, then pressing or drawing one side, and including a recess on one side. An electrode assembly (100A) is accommodated in the recess (not shown). A sealing portion (210) is formed on the outer periphery of the recess, and the sealing portion (210) is sealed by a method such as heat fusion while the electrode assembly (100A) is accommodated in the recess.

[0073] Hereinafter, an electrode assembly according to one embodiment of the present invention will be described in more detail with reference to the drawings.

[0074] Fig. 2 is a perspective view showing only the electrode assembly extracted from Fig. 1, and Fig. 3 is a cross-sectional view of the first reinforcing member of Fig. 2 taken along line A-A'.

[0075] Referring to FIGS. 2 and 3, an electrode assembly (100A) according to one embodiment of the present invention includes a first reinforcing member (140).

[0076] The first reinforcing member (140) is installed on the outer surface of one of the first electrode plates (110) and the second electrode plates (120), which is located at the outermost end. The first reinforcing member (140) is made of a metal plate. This first reinforcing member (140) improves the rigidity of the outermost end of the electrode assembly (100A).

[0077] In addition, the first reinforcing member (140) may be formed to have a size corresponding to one of the first electrode plates (110) and the second electrode plates (120) located at the outermost end. In addition, the first reinforcing member (140) may be, for example, a thin film made of stainless steel (SUS) having an adhesive layer on one surface. In this case, the thickness of the first reinforcing member (140) may be included in the range of 3% to 5% of the total thickness of the electrode assembly (100A).

[0078] If the thickness of the first reinforcing member (140) exceeds 5% of the total thickness of the electrode assembly (100A), the thickness of the electrode assembly (100A) may increase excessively. If the thickness of the first reinforcing member (140) is less than 2% of the total thickness of the electrode assembly (100A), it may be difficult for the first reinforcing member (140) to improve the rigidity of the outermost portion of the electrode assembly (100A).

[0079] More specifically, regarding the first reinforcing member (140), when the first electrode plate (110) is positioned at the outermost end among the first electrode plates (110) and second electrode plates (120) that are laminated in multiple layers as described above, the first electrode plate (110) may be a single-sided cathode. In addition, the first reinforcing member (140) may be installed at the single-sided cathode.

[0080] On the other hand, when the second electrode plate (120) is positioned at the outermost part of the electrode assembly (100A), the second electrode plate (120) may be a single-sided cathode, and the first reinforcing member (140) may be installed on the single-sided cathode. The single-sided cathode may have its rigidity improved to be higher than that of a double-sided cathode by the first reinforcing member (140). Therefore, since the occurrence of meandering and curling can be prevented, the occurrence of interfacial unevenness due to curling, which causes performance deterioration during repeated charging and discharging, can also be prevented. Therefore, the lifespan of the secondary battery can be improved.

[0081] Figure 4 is a drawing showing a modified example of the first reinforcing member.

[0082] Referring to FIG. 4, the first reinforcing member (140) may be configured in a modified manner so that the thickness decreases from one end adjacent to the first electrode substrate tab (111) of the first electrode plate (110) and the second electrode substrate tab (121) of the second electrode plate (120) to the other end.

[0083] Accordingly, the rigidity of the portion where the first electrode substrate tab (111) and the second electrode substrate tab (121) are positioned in the electrode assembly (100A) can be further improved while minimizing the increase in the overall thickness.

[0084] FIG. 5 is a perspective view illustrating a process of creating a second reinforcing member in an electrode assembly according to another embodiment of the present invention.

[0085] Referring to FIG. 5, an electrode assembly (100B) according to another embodiment of the present invention may include a second reinforcing member (150).

[0086] The second reinforcing member (150) can further improve the rigidity of the outermost electrode plate (100B) among the first electrode plate (110) and the second electrode plate (120). The second reinforcing member (150) can be made of a polymer.

[0087] As an example of a method for forming such a second reinforcing member (150) at the outermost portion of the electrode assembly (100B), a method may be used in which a liquid polymer is applied to a target thickness using a slit coater (C) and then cured using heat. Such a second reinforcing member (150) can improve the rigidity of the cross-sectional cathode located at the outermost portion among the first electrode plate (110) and the second electrode plate (120).

[0088] The thickness of the second reinforcing member (150) may be within a range of 3% to 5% of the total thickness of the electrode assembly (100B). If the thickness of the second reinforcing member (150) exceeds 5% of the total thickness of the electrode assembly (100B), the thickness of the electrode assembly (100A) may be excessively increased. If the thickness of the second reinforcing member (150) is less than 2% of the total thickness of the electrode assembly (100A), it may be difficult for the second reinforcing member (150) to improve the rigidity of the outermost portion of the electrode assembly (100B).

[0089] Meanwhile, the polymer may be, for example, a mixture of ethylene-vinyl acetate copolymer (EVA), linear low density polyethylene (LLDPE), and talc.

[0090] Here, the ethylene vinyl acetate copolymer may be 55 to 60 wt%, the linear low-density polyethylene may be 20 to 25 wt%, and the talc may be 15 to 25 wt% relative to the polymer weight. Since such a polymer has high rigidity, it can prevent deformation of the cross-sectional cathode located at the outermost part of the electrode assembly (100B) among the first electrode plate (110) and the second electrode plate (120).

[0091] FIG. 6 is a perspective view illustrating an electrode assembly according to another embodiment of the present invention, and FIG. 7 is a perspective view illustrating a process of creating a second reinforcing member on a first reinforcing member in an electrode assembly according to another embodiment of the present invention.

[0092] Referring to FIGS. 6 and 7, an electrode assembly (100C) according to another embodiment of the present invention may further include a second reinforcing member (150) while including a first reinforcing member (140).

[0093] The second reinforcing member (150) is made of a polymer and can wrap around the outside of the first reinforcing member (140). At this time, the first reinforcing member (140) described above can be formed to have a size that is relatively smaller than one of the first electrode plate (110) and the second electrode plate (120) located at the outermost end. In addition, the second reinforcing member (150) can be formed to have a width that is relatively larger than the first reinforcing member (140) so as to wrap around the first reinforcing member (140).

[0094] As an example of a method for producing the second reinforcing member (150) as described above on the outside of the first reinforcing member (140), a method of applying a liquid polymer using a slit coater (C) and then curing it as described above can be used. This second reinforcing member (150) not only further improves the rigidity of the cross-sectional cathode located at the outermost end among the first electrode plate (110) and the second electrode plate (120), but also enables the first reinforcing member (140) to be stably coupled to the cross-sectional cathode.

[0095] While various embodiments of the present invention have been described above, the drawings and detailed description of the invention described so far are merely illustrative of the present invention, and are used solely for the purpose of explaining the present invention and are not intended to limit the meaning or scope of the present invention as set forth in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent embodiments are possible. Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

[0096] - Explanation of symbols -

[0097] 10: Secondary battery

[0098] 100A, 100B, 100C: Electrode assembly

[0099] 110: First electrode plate

[0100] 120: Second electrode plate

[0101] 130: Membrane

[0102] 140: First reinforcing member

[0103] 150: Second reinforcing member

Claims

1. First electrode plate and second electrode plate; A separator interposed between the first electrode plate and the second electrode plate; and An electrode assembly comprising a first reinforcing member installed on the outer surface of one of the first electrode plates and the second electrode plate, wherein the first reinforcing member is a metal plate.

2. In paragraph 1, An electrode assembly further comprising a second reinforcing member surrounding the outside of the first reinforcing member, wherein the second reinforcing member is made of a polymer.

3. In paragraph 2, An electrode assembly in which the second reinforcing member has a relatively larger width than the first reinforcing member so as to surround the first reinforcing member.

4. In paragraph 2, The above polymer is an electrode assembly which is a mixture of ethylene-vinyl acetate copolymer (EVA), linear low density polyethylene (LLDPE) and talc.

5. In paragraph 2, An electrode assembly in which the ethylene vinyl acetate copolymer is 55 to 60 wt%, the linear low-density polyethylene is 20 to 25 wt%, and the talc is 15 to 25 wt%, relative to the weight of the polymer.

6. In paragraph 2, An electrode assembly wherein the thickness of the second reinforcing member is within a range of 3% to 5% of the total thickness of the electrode assembly.

7. In paragraph 1, An electrode assembly in which the first reinforcing member is formed to have a size relatively smaller than one of the first electrode plate and the second electrode plate located at the outermost end.

8. In paragraph 1, An electrode assembly in which the first reinforcing member has a size corresponding to one of the first and second electrode plates located at the outermost end.

9. In paragraph 1, The above first reinforcing member is an electrode assembly made of a thin film of stainless steel having an adhesive layer on one surface.

10. In paragraph 1, An electrode assembly in which the first reinforcing member is formed such that the thickness decreases from one end adjacent to the first electrode substrate tab of the first electrode plate and the second electrode substrate tab of the second electrode plate to the other end.

11. In paragraph 1, An electrode assembly wherein the thickness of the first reinforcing member is within a range of 3% to 5% of the total thickness of the electrode assembly.

12. First electrode plate and second electrode plate; A separator interposed between the first electrode plate and the second electrode plate; and A second reinforcing member installed on the outer surface of one of the first and second electrode plates located at the outermost end; The above second reinforcing member is an electrode assembly made of polymer.

13. In paragraph 12, The above polymer is an electrode assembly which is a mixture of ethylene-vinyl acetate copolymer (EVA), linear low density polyethylene (LLDPE) and talc.

14. In paragraph 12, An electrode assembly in which the ethylene vinyl acetate copolymer is 55 to 60 wt%, the linear low-density polyethylene is 20 to 25 wt%, and the talc is 15 to 25 wt%, relative to the weight of the polymer.

15. In paragraph 12, An electrode assembly wherein the thickness of the second reinforcing member is within a range of 3% to 5% of the total thickness of the electrode assembly.

16. An electrode assembly according to any one of claims 1 to 15; and A secondary battery comprising a case accommodating the electrode assembly.

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