Electrode assembly and secondary battery comprising same

Abstract

The present invention relates to an electrode assembly and a secondary battery comprising same, wherein, in the electrode assembly, impregnation with an electrolyte solution is facilitated near a central portion of the electrode assembly where compressive stress is high, and a reaction area is increased, thus ensuring that, during rapid charging, intercalation and deintercalation of lithium can proceed smoothly, thereby suppressing the occurrence of lithium plating and enabling a uniform reaction, and enabling problems at the central portion to be improved by improving the unfavorable negative-to-positive electrode ratio (NP ratio) typically caused by stress concentration at the central portion.

Description

Electrode assembly and secondary battery including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0182451 filed December 10, 2024 and Korean Patent Application No. 10-2025-0167407 filed November 7, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to an electrode assembly and a secondary battery including the same. The invention enables good electrolyte impregnation and an expanded reaction area near the center of the electrode assembly where compressive stress is high, thereby allowing for smooth insertion and extraction of lithium during rapid charging, which can suppress lithium precipitation and induce a uniform reaction. Furthermore, it improves the problem situation in the center by improving the inferior positive-negative ratio (NP ratio) that is typically caused by stress concentration in the center.

[0005] Secondary batteries are classified according to the shape of the battery case into cylindrical and prismatic batteries, in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and pouch-type batteries, in which the electrode assembly is embedded in a pouch-type case made of aluminum laminate sheets.

[0006] In addition, the electrode assembly embedded in the battery case is a power generation element capable of charging and discharging, comprising a stacked structure of a positive electrode, a separator, and a negative electrode, and can be classified into a jellyroll-type structure in which a separator is interposed between long sheet-type positive and negative electrodes coated with an active material and wound, a stack-type structure in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked with a separator interposed, and a stack / folding-type electrode assembly in which bicells or full cells are wound by stacking positive and negative electrodes of a predetermined unit with a separator interposed.

[0007] Among them, jelly-roll type electrode assemblies are widely produced due to their advantages of ease of manufacturing and high energy density per unit weight. A jelly-roll type electrode assembly could be manufactured by assembling a laminate comprising long sheet-type positive and negative electrodes with a separator interposed between them, and then winding the sheet along its length while a winding core is in contact with one end of the electrode laminate. Furthermore, this jelly-roll type electrode assembly can be inserted into a battery case made of a cylindrical metal can to form a cylindrical secondary battery.

[0008] Conventionally, in cylindrical secondary batteries, the presence of an outer rigid battery case (typically made of a can) caused compressive stress to occur near the core (where empty space exists) to relieve stress resulting from the expansion of the jellyroll-type electrode assembly during charging. In these stress-concentrated regions, the electrolyte becomes locally insufficient, leading to an increase in resistance and consequently, lithium (Li) precipitation. Particularly during rapid charging, lithium insertion and extraction do not occur smoothly, resulting in uneven reactions on the surface and causing lithium precipitation problems. Furthermore, due to stress concentration in the core, the positive-negative ratio (NP ratio) was typically inferior in the core. This could be a factor that further accelerates lithium precipitation.

[0009] When lithium precipitation occurs, the electrode thickness increases, leading to further compressive stress. This strongly compresses the porous separator, causing the lithium precipitation area to gradually expand from the core to the outer part. Consequently, abnormal heat generation behavior may be exhibited, and the risk of ignition increases significantly. The pores of the separator become clogged due to compressive stress, and the influence of the electrode byproduct layer causes a rapid increase in resistance and heat generation. These continuous side reactions and lithium precipitation cause the jelly-roll type electrode assembly to expand, which was the cause of battery case rupture and even explosion. Therefore, research was required to resolve these issues.

[0010] The present invention has been devised to solve the above-mentioned problems. The objective of the present invention is to provide an electrode assembly and a secondary battery including the same, which can improve the problem situation in the center by ensuring good electrolyte impregnation and expanding the reaction area near the center of the electrode assembly where compressive stress is high, thereby allowing smooth insertion and extraction of lithium during rapid charging, suppressing the occurrence of lithium precipitation, inducing a uniform reaction, and improving the poor positive-negative ratio (NP ratio) that is typically caused by stress concentration in the center.

[0011] The electrode assembly according to the present invention relates to an electrode assembly in which a first electrode, a separator, and a second electrode are alternately stacked and wound to form a wound center, wherein the first electrode is

[0012] A current collector; and an electrode active material layer formed on at least one surface of the current collector, wherein the electrode active material layer comprises: a first active material layer having a first pattern shape formed by a plurality of pores; and a second active material layer formed on a region of the current collector where the first active material layer is not formed and having a second pattern shape formed by a plurality of pores, wherein the first active material layer is formed closer to the center of the winding than the second active material layer, and the depth (d1) of the pores of the first pattern shape is formed deeper than the depth (d2) of the pores of the second pattern shape, or the spacing (s1) between the pores of the first pattern shape is formed smaller than the spacing (s2) between the pores of the second pattern shape.

[0013] The depth (d1) of the pores of the first pattern shape is formed deeper than the depth (d2) of the pores of the second pattern shape, and the spacing (s1) between the pores of the first pattern shape can be formed with a smaller spacing than the spacing (s2) between the pores of the second pattern shape.

[0014] The electrode active material layer comprises a one-sided electrode active material layer formed on one side of a current collector; and a other-sided electrode active material layer formed on the other side of a current collector, and the first active material layer and the second active material layer may be included in the one-sided electrode active material layer.

[0015] The pore shapes included in the first pattern shape and the second pattern shape may be provided in multiple columns and multiple rows.

[0016] The longitudinal length (L1) of the first active material layer may be 24% to 26% of the total length (L) of the portion where the electrode active material layer is formed at the first electrode.

[0017] The depth (d1) of the pores of the first pattern shape is 40% to 70% of the thickness (H) of the first electrode, and the spacing (s1) between the pores of the first pattern shape can be 30 µm to 200 µm.

[0018] The depth (d2) of the pores in the second pattern shape may be 30% to 70% of the depth (d1) of the pores in the first pattern shape.

[0019] The spacing between pores (s2) of the second pattern shape may be greater than 100% and less than or equal to 300% of the spacing between pores (s1) of the first pattern shape.

[0020] In the region of the electrode active material layer corresponding to a length (B) of 5% to 25% of the total length (L) of the electrode active material layer from the end of the winding portion of the electrode active material layer, a pattern shape provided as a pore may not be formed.

[0021] The electrode active material layer includes a third active material layer having a third pattern shape formed by a plurality of pores, and the depth of the pores of the third pattern shape may be different from the depth of the pores of the first pattern shape.

[0022] The electrode active material layer includes a third active material layer having a third pattern shape formed by a plurality of pores, and the depth of the pores of the third pattern shape may be different from the depth of the pores of the second pattern shape.

[0023] The first electrode may be a negative electrode, and the second electrode may be a positive electrode.

[0024] A secondary battery according to the present invention comprises an electrode assembly described above and a battery case in which the electrode assembly is housed.

[0025] The electrode assembly according to the present invention and the secondary battery including the same can suppress the occurrence of lithium precipitation and induce a uniform reaction by ensuring good electrolyte impregnation and expanding the reaction area near the center of the electrode assembly where compressive stress is high, thereby allowing the insertion and extraction of lithium to occur smoothly during rapid charging, and can improve the problem situation in the center by improving the inferior positive-negative ratio (NP ratio) that is typically caused by stress concentration in the center.

[0026] FIG. 1 is a cross-sectional view illustrating a cylindrical secondary battery including an electrode assembly of the present invention.

[0027] FIG. 2 is a plan view illustrating the appearance of the first electrode when it is laid out on a plane in an electrode assembly according to Example 1 of the present invention.

[0028] Figure 3 is a cross-sectional view along A-A' of Figure 2.

[0029] FIG. 4 is a cross-sectional view illustrating the first electrode in an electrode assembly according to Example 2 of the present invention.

[0030] Hereinafter, preferred embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited or restricted by the following embodiments.

[0031] In order to clearly explain the present invention, detailed descriptions of related prior art that are irrelevant to the explanation or that may unnecessarily obscure the essence of the invention have been omitted. Furthermore, when assigning reference numerals to the components of each drawing in this specification, identical or similar reference numerals are assigned to identical or similar components throughout the entire specification.

[0032] Furthermore, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0033]

[0034] FIG. 1 is a longitudinal cross-sectional view illustrating a cylindrical secondary battery including an electrode assembly of the present invention. FIG. 2 is a plan view illustrating the appearance of a first electrode when unfolded on a plane in an electrode assembly according to Example 1 of the present invention. FIG. 3 is a cross-sectional view along A-A' of FIG. 2. FIG. 4 is a cross-sectional view illustrating a first electrode in an electrode assembly according to Example 2 of the present invention.

[0035] Referring to FIG. 1, FIG. 1 illustrates a cylindrical secondary battery (1) including an electrode assembly (10) of the present invention. The cylindrical secondary battery (1) may include a jelly-roll type electrode assembly (10) formed by alternately stacking and winding a first electrode (11), a separator (13), and a second electrode (12). The cylindrical secondary battery (1) may include a battery case (20) that accommodates the electrode assembly (10) in an internal space. The internal structure of the cylindrical secondary battery (1) is illustrated in FIG. 1. Since the internal structure, which is unrelated to the features of the present invention, is the same as the internal structure of a general cylindrical battery in the art, it will be omitted from this description.

[0036] The electrode assembly (10) according to Example 1 of the present invention may be an electrode assembly (10) contained within a battery case (20) of a cylindrical battery as described above. The electrode assembly (10) according to Example 1 of the present invention relates to an electrode assembly (10) in which a first electrode (11), a separator (13), and a second electrode (12) are alternately stacked and wound to form a wound center (30).

[0037] FIG. 2 illustrates a state in which the first electrode is laid out on a plane in an electrode assembly (10) according to Example 1 of the present invention. FIG. 3 is a cross-sectional view along A-A' of FIG. 2.

[0038] Referring to FIGS. 2 and 3, an electrode assembly (10) according to Embodiment 1 of the present invention may include a first electrode (11) and a second electrode (12). Here, the first electrode (11) may be a negative electrode, for example. The second electrode (12) may be a positive electrode opposite to the first electrode (11). Here, the first electrode (11) may include a current collector (200) and an electrode active material layer (100). The current collector (200) may be in the form of a foil made of metal. The electrode active material layer (100) may include an active material, a conductive material, and a binder. The electrode active material layer (100) may be formed on at least one surface of the current collector (200).

[0039] The electrode active material layer (100) includes a first active material layer (110) and a second active material layer (120). The first active material layer (110) may be a portion of the electrode active material layer (100) where a first pattern shape (111), provided with a plurality of pores, is formed. The plurality of pores may be pores formed by creating grooves that are indented inward. These pores may appear circular when viewed in a plan view (see FIG. 2). Of course, the shape shown in the plan view may be a polygonal shape such as a triangle or a square in addition to a circle. The second active material layer (120) is formed on an area of ​​the current collector where the first active material layer (110) is not formed. It may be a portion where a second pattern shape (121), provided with a plurality of pores, is formed. In the case of the second pattern shape (121), the shape of the pores may also be pores formed in the same way as in the first pattern shape (111). That is, the multiple pores may be pores formed by creating inwardly recessed grooves. These pores may be circular when viewed in a plan view, and may also be polygonal shapes such as triangles or squares. In addition, the size of the opening of the second pattern shape (121) groove may be the same or larger.

[0040] And, in the first electrode (11) of the electrode assembly (10) according to Example 1 of the present invention, the first active material layer (110) is formed closer to the winding center (30) than the second active material layer (120). And, at this time, the depth (d1) of the pores of the first pattern shape (111) is formed deeper than the depth (d2) of the pores of the second pattern shape (121), or the spacing (s1) between the pores of the first pattern shape (111) is formed with a smaller spacing than the spacing (s2) between the pores of the second pattern shape (121).

[0041] And, the electrode assembly (10) according to Example 1 of the present invention can be an 'or' combination as well as an 'and' combination.

[0042] That is, the depth (d1) of the pores of the first pattern shape (111) is formed deeper than the depth (d2) of the pores of the second pattern shape (121), and (and) the spacing (s1) between the pores of the first pattern shape (111) can be formed with a smaller spacing than the spacing (s2) between the pores of the second pattern shape (121).

[0043] The formation of pores basically has the effect of increasing the surface area of ​​the electrode active material layer (100). This can increase the electrolyte impregnation and make the reaction more smooth. Based on this background, the above characteristic configuration of the present invention can produce a more special effect.

[0044] That is, the electrode assembly (10) according to Example 1 of the present invention has a pattern shape in which pores are formed to facilitate a smooth reaction overall, while also ensuring good electrolyte impregnation near the center of the electrode assembly (10) where compressive stress is high and expanding the reaction area, thereby allowing the insertion and extraction of lithium to occur smoothly during rapid charging, and thus suppressing the occurrence of lithium precipitation.

[0045] There may be multiple cases in which the electrolyte impregnation is well done near the center of the electrode assembly (10) with high compressive stress and the reaction area is widened so that the insertion and extraction of lithium during rapid charging can occur smoothly.

[0046] Specifically, there may be a method to form the depth (d1) of the pores of the first pattern shape (111) deeper than the depth (d2) of the pores of the second pattern shape (121).

[0047] Alternatively, there may be a method to form the spacing (s1) between the pores of the first pattern shape (111) as smaller than the spacing (s2) between the pores of the second pattern shape (121).

[0048] Alternatively, there may be a method to have both of these simultaneously. That is, a method in which the depth (d1) of the pores of the first pattern shape (111) is formed deeper than the depth (d2) of the pores of the second pattern shape (121), and (and) the spacing (s1) between the pores of the first pattern shape (111) is formed to be smaller than the spacing (s2) between the pores of the second pattern shape (121).

[0049] Meanwhile, the electrode assembly (10) according to Example 1 of the present invention can induce a uniform reaction as the pore shapes included in the first pattern shape (111) and the second pattern shape (121) are provided in a plurality of columns and a plurality of rows.

[0050] In addition, the electrode assembly (10) according to Embodiment 1 of the present invention can improve the problem situation regarding the positive-negative ratio (NP ratio) on the central side by forming pores deeper and at closer intervals on the side closer to the center of the winding (30) where stress is concentrated. That is, typically, the positive-negative ratio (NP ratio) is inferior on the central side due to stress concentration, but by improving this, the problem situation on the central side can be improved.

[0051] In addition, in the electrode assembly (10) according to Embodiment 1 of the present invention, the electrode active material layer (100) may include a one-sided electrode active material layer (140) formed on one side of a current collector and a other-sided electrode active material layer (150) formed on the other side of a current collector. Based on FIG. 3, the electrode active material layer (100) coated on the upper surface of the current collector may be the one-sided electrode active material layer (140), and the electrode coated on the lower surface of the current collector may be the other-sided electrode active material layer (150). Referring to FIG. 3, the first active material layer (110) and the second active material layer (120) described above may be included in the one-sided electrode active material layer (140). Since this form allows the first pattern shape (111) and the second pattern shape (121) to be formed on one side, they can be formed together on one side, which may be more advantageous during electrode manufacturing and processing.

[0052] Referring to FIGS. 2 and 3, the longitudinal length (L1) of the first active material layer (110) may be 24% to 26% of the total length (L) of the portion where the electrode active material layer (100) is formed in the first electrode (11). Since the length of this portion is set to correspond to the portion where stress is concentrated, the electrode assembly (10) can be manufactured more efficiently.

[0053] In addition, in the electrode assembly (10) according to Embodiment 1 of the present invention, the depth (d1) of the pores of the first pattern shape (111) may be 40% to 70% of the thickness (H) of the first electrode (11). In addition, the spacing (s1) between the pores of the first pattern shape (111) may be 30 µm to 200 µm.

[0054] The pores of the second pattern shape (121) may be shallower than the pores of the first pattern shape (111). Specifically, the depth (d2) of the pores of the second pattern shape (121) may be 30% to 70% of the depth (d1) of the pores of the first pattern shape (111). Also, the spacing between the pores of the second pattern shape (121) may be larger than the spacing between the pores of the first pattern shape (111). Specifically, the spacing between the pores (s2) of the second pattern shape (121) may be greater than 100% to less than 300% of the spacing between the pores (s1) of the first pattern shape (111).

[0055] Since the electrical capacitance and reaction efficiency can vary depending on the numerical values ​​of pore depth and spacing, and these factors change in an interrelationship, uniformly high or low values ​​may not necessarily be better. Therefore, the numerical range values ​​described above can also be an important factor.

[0056] In the electrode assembly (10) according to Example 1 of the present invention, the first electrode (11) may not have a pattern shape formed as pores in the region (B) of the electrode active material layer (100) corresponding to a length of 5% to 25% of the total length (L) of the electrode active material layer (100) from the end of the winding end portion (40) of the electrode active material layer (100). This is set by distinguishing between a region where an increase in reaction is required and a region where it is not required, and in a place where an increase in electrical capacitance is sought rather than an increase in reaction, a pattern shape of pores or grooves may not be formed.

[0057] In the electrode assembly (10) according to Example 1 of the present invention, the first electrode (11) may be a negative electrode and the second electrode may be a positive electrode. Since the negative electrode is typically formed to be longer than the positive electrode, when the first electrode (11) is the negative electrode, the features of the present invention described above can be implemented in the first electrode (11), which is the longer electrode.

[0058] Meanwhile, the secondary battery (1) according to the present invention may be configured to include an electrode assembly (10) according to Example 1 of the present invention and a battery case (20) that accommodates the electrode assembly (10) inside. The secondary battery (1) may exhibit the same effect as that exhibited in the electrode assembly (10) according to Example 1 of the present invention described above.

[0059]

[0060] Example 2

[0061] FIG. 4 is a cross-sectional view illustrating the first electrode in an electrode assembly according to Example 2 of the present invention.

[0062] Example 2 of the present invention differs from Example 1 in that, compared to the electrode assembly according to Example 1 of the present invention, a third pattern shape (131) provided with a plurality of pores is further formed on the other side of the current collector.

[0063] Content common to Example 1 will be omitted as much as possible, and Example 2 will be described. That is, it is obvious that if content not explained in Example 2 is necessary, it can be considered as content of Example 1.

[0064] Referring to FIG. 4, in the electrode assembly according to Embodiment 2 of the present invention, the electrode active material layer (100) of the first electrode (11') may include a one-sided electrode active material layer (140) formed on one side of the current collector and a other-sided electrode active material layer (150) formed on the other side of the current collector. For example, based on the drawing, the electrode active material layer (100) coated on the upper surface of the current collector may be the one-sided electrode active material layer (140), and the electrode coated on the lower surface of the current collector may be the other-sided electrode active material layer (150).

[0065] In addition, a first active material layer (110) having a first pattern shape (111) formed with a plurality of pores and a second active material layer (120) having a second pattern shape (121) formed with a plurality of pores may be included in one side electrode active material layer (140). As in Example 1, the first active material layer (110) is formed closer to the winding center (30) than the second active material layer (120). Also, the depth (d1) of the pores of the first pattern shape (111) is formed deeper than the depth (d2) of the pores of the second pattern shape (121), or the spacing between the pores of the first pattern shape (111) is formed to be smaller than the spacing between the pores of the second pattern shape (121).

[0066] Of course, the depth (d1) of the pores of the first pattern shape (111) may be formed deeper than the depth (d2) of the pores of the second pattern shape (121), and (and) the spacing (s1) between the pores of the first pattern shape (111) may be formed smaller than the spacing (s2) between the pores of the second pattern shape (121).

[0067] However, the electrode assembly according to Embodiment 2 of the present invention may include a third active material layer (130) in the other side electrode active material layer (150). The third active material layer (130) may be an active material layer in which a third pattern shape (131) formed by a plurality of pores is formed. In addition, the depth of the pores of the third pattern shape (131) may differ from the depth of the pores of the first pattern shape (111). Referring to FIG. 4, the depth of the pores of the third pattern shape (131) may be shallower than the depth of the pores of the first pattern shape (111). That is, the depth of the pores may be relatively deeper in the first pattern shape (111) than in the third pattern shape (131).

[0068] Also, the depth of the pores in the third pattern shape (131) may differ from the depth of the pores in the second pattern shape (121). Referring to FIG. 4, the depth of the pores in the third pattern shape (131) may be deeper than the depth of the pores in the second pattern shape (121). That is, the depth of the pores may be relatively shallower in the second pattern shape (121) than in the third pattern shape (131). By varying the depth of the pores at different locations in this way, mutually complementary effects can be obtained at each location. That is, when the electrical capacitance may be insufficient if the pores are made deep at one location to prioritize impregnation and reactivity, the electrical capacitance can be supplemented by making the pore depth shallow at another location. In this way, superior results can be obtained by combining them in a mutually complementary manner.

[0069]

[0070] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

[0071] [Explanation of the symbol]

[0072] 1: Secondary battery

[0073] 10: Electrode assembly

[0074] 11: First electrode

[0075] 12: Second electrode

[0076] 13: Separator

[0077] 20: Battery case

[0078] 30: Center of the coil

[0079] 40: Winding end

[0080] 100: Electrode active material layer

[0081] 110: First active material layer

[0082] 111: First pattern shape

[0083] 120: Second active material layer

[0084] 121: Second pattern shape

[0085] 130: Third active material layer

[0086] 131: Third pattern shape

[0087] 140: One-sided electrode active material layer

[0088] 150: Burning electrode active material layer

[0089] 200: Whole house

[0090] C: Center of the winding

[0091] E: End of the winding

Claims

1. An electrode assembly in which a first electrode, a separator, and a second electrode are alternately stacked and wound to form a wound center, wherein The first electrode above is, The whole house; and It includes an electrode active material layer formed on at least one surface of the above-mentioned current collector, and The above electrode active material layer is, A first active material layer having a first pattern shape formed by a plurality of pores; and It includes a second active material layer formed on the region of the current collector where the first active material layer is not formed, and having a second pattern shape formed with a plurality of pores. The first active material layer is formed closer to the center of the winding than the second active material layer, and The depth (d1) of the pore in the first pattern shape is formed deeper than the depth (d2) of the pore in the second pattern shape, or An electrode assembly characterized in that the spacing (s1) between pores of the first pattern shape is formed to be smaller than the spacing (s2) between pores of the second pattern shape.

2. In Claim 1, The depth (d1) of the pore in the first pattern shape is formed deeper than the depth (d2) of the second pattern shape, and also An electrode assembly characterized in that the spacing (s1) between pores of the first pattern shape is formed to be smaller than the spacing (s2) between pores of the second pattern shape.

3. In claim 1 or 2, The above electrode active material layer A single-sided electrode active material layer formed on one side of the above-mentioned current collector; and It includes a secondary surface electrode active material layer formed on the secondary surface of the above-mentioned current collector, and An electrode assembly characterized in that the first active material layer and the second active material layer are included in the one-sided electrode active material layer.

4. In claim 1 or 2, An electrode assembly characterized in that the pore shape included in the first pattern shape and the second pattern shape is provided in a plurality of columns and a plurality of rows.

5. In claim 1 or 2, An electrode assembly characterized in that the longitudinal length (L1) of the first active material layer is 24% to 26% of the total length (L) of the portion in which the electrode active material layer is formed at the first electrode.

6. In claim 1 or 2, The depth (d1) of the pore of the first pattern shape is 40% to 70% of the first electrode thickness (H), and An electrode assembly characterized in that the spacing (s1) between the pores of the first pattern shape is 30 µm to 200 µm.

7. In Claim 5, The depth (d2) of the pore in the second pattern shape is 30% to 70% of the depth (d1) of the first pattern shape, and An electrode assembly characterized in that the spacing between pores (s2) of the second pattern shape is greater than 100% and less than or equal to 300% of the spacing between pores (s1) of the first pattern shape.

8. In claim 1 or 2, An electrode assembly characterized in that a pattern shape provided as a pore is not formed in a region (B) of the electrode active material layer corresponding to a length of 5% to 25% of the total length (L) of the electrode active material layer from the end of the winding portion of the electrode active material layer.

9. In Claim 3, The above-mentioned electrode active material layer is, It includes a third active material layer having a third pattern shape formed by a plurality of pores, and An electrode assembly characterized in that the depth of the pores of the third pattern shape is different from the depth of the pores of the first pattern shape.

10. In Claim 3, The above-mentioned electrode active material layer is, It includes a third active material layer having a third pattern shape formed by a plurality of pores, and An electrode assembly characterized in that the depth of the pores of the third pattern shape is different from the depth of the pores of the second pattern shape.

11. In claim 1 or 2, An electrode assembly characterized in that the first electrode is a negative electrode and the second electrode is a positive electrode.

12. Electrode assembly according to claim 1 or 2; and A secondary battery comprising a battery case in which the above electrode assembly is housed.

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