Electrode assembly and secondary battery containing the same

Abstract

The present invention relates to an electrode assembly and a secondary battery including the same. An electrode assembly according to one embodiment of the present invention is formed by winding a first electrode, a first separator, a second electrode, and a second separator, and the electrode assembly may include a protective member disposed in a space between each of the first separator and the second separator and an edge portion where winding of the first electrode begins, and having a shape corresponding to at least a portion of the space.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0104376 filed on August 19, 2022 and Korean Patent Application No. 10-2023-0107156 filed on August 16, 2023, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to an electrode assembly and a device including the same, and more particularly, to an electrode assembly capable of improving safety and a secondary battery including the same.

Background Art

[0003] In recent years, the demand for portable electronic products such as notebook computers, video cameras, and mobile phones has increased rapidly. As the development of electric vehicles, energy storage batteries, robots, satellites, etc. has become full-scale, many studies have been conducted on secondary batteries used as their driving power sources.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries according to the shape of the battery case. The electrode assembly installed inside the battery case is a rechargeable power generation element having a structure in which electrodes and separators are laminated.

[0005] When the charge-discharge cycle of a secondary battery including such an electrode assembly is repeated, swelling occurs in which the electrode assembly bulges, and the winding center portion of the electrode assembly may be deformed. If the winding center portion of the electrode assembly cannot maintain a circular shape and is deformed, an internal short circuit or disconnection may occur during the charge-discharge cycle, and the safety may be significantly reduced.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Embodiments of the present invention aim to provide an electrode assembly and a secondary battery containing the same that can improve safety.

[0007] The technical problems of the present invention are not limited to those mentioned above, and other technical problems not mentioned can be clearly understood by an ordinary person from the following description. [Means for solving the problem]

[0008] An electrode assembly according to one embodiment of the present invention is formed by winding together a first electrode, a first separator, a second electrode, and a second separator, and the electrode assembly may include a protective member disposed in the space between each of the first separator and the second separator and the edge portion where the winding of the first electrode begins, and having a shape corresponding to at least a portion of the space.

[0009] According to one embodiment, the protective member can be positioned to surround the edge portion where the winding of the first electrode begins at least once. According to one embodiment, the first electrode includes a first current collector and a first active material layer disposed on the first current collector, and the protective member can be formed to surround the side surface of the first current collector and the side surface of the first active material layer included in the first electrode.

[0010] According to one embodiment, the protective member can come into contact with the side surface of the first current collector and the side surface of the first active material layer, which are facing the winding center. According to one embodiment, the protective member may include a first protective member disposed between the first separator and the edge portion where winding of the first electrode begins, and a second protective member disposed between the second separator and the edge portion where winding of the first electrode begins.

[0011] According to one embodiment, a portion of the first protective member and a portion of the second protective member can be arranged to contact each other between the first separator and the second separator.

[0012] According to one embodiment, at least one of the first protective member and the second protective member can be arranged to wind the plain portion of the second electrode at least once.

[0013] According to one embodiment, at least one of the first protective member and the second protective member can be wound at least once between the winding center of the electrode assembly and the edge portion where winding of the first electrode begins, and can be wound at least once between the winding outer casing of the electrode assembly and the edge portion where winding of the first electrode begins.

[0014] According to one embodiment, at least one of the first separator and the second separator may have a region in contact with the protective member that is more rigid than the region that does not come into contact with the protective member.

[0015] According to one embodiment, at least one of the first separator and the second separator includes a plurality of voids formed near the protective member, and a portion of the protective member can be located within the voids of at least one of the first separator and the second separator.

[0016] According to one embodiment, the protective member can be formed from a thermoplastic resin. According to one embodiment, the protective member may include a hot-melt adhesive sheet that melts at high temperatures and returns to a solid state at low temperatures.

[0017] According to another embodiment, the protective member can be attached to only one of the first separator and the second separator. A secondary battery according to one embodiment of the present invention may include the electrode assembly described above. [Effects of the Invention]

[0018] According to an embodiment of the present invention, in an electrode assembly, a protective member can be included that is disposed between an edge portion where winding of the positive electrode starts and a separator. By this protective member and the separator, cracking of the negative electrode at a portion in contact with the edge portion of the positive electrode is prevented to prevent disconnection and short circuit, thereby improving the safety of the secondary battery.

[0019] Also, according to an embodiment of the present invention, by the protective member and the separator, the winding center portion of the electrode assembly can be easily maintained in a circular shape. Thereby, it is possible to prevent an internal short circuit from occurring during charge and discharge cycles of the secondary battery including the electrode assembly, and safety can be ensured. In addition to this, various effects directly or indirectly grasped by this document can be provided.

Brief Description of the Drawings

[0020] [Figure 1] It is a perspective view showing a secondary battery including an electrode assembly according to a first embodiment of the present invention. [Figure 2] It is an exploded perspective view showing an unfolded state before the electrode assembly shown in FIG. 1 is wound. [Figure 3] It is a cross-sectional view showing an unfolded state before the electrode assembly shown in FIG. 1 is wound. [Figure 4a] It is a cross-sectional view showing an enlarged example of a portion adjacent to the winding center portion (C) of the electrode assembly according to a first embodiment of the present invention. [Figure 4b] It is a cross-sectional view showing another enlarged example of a portion adjacent to the winding center portion (C) of the electrode assembly according to a first embodiment of the present invention. [Figure 5a] It is a view showing a part of a protective member disposed on a separator before winding of the electrode assembly according to a first embodiment of the present invention. [Figure 5b] It is a view showing a part of a protective member disposed on a separator shown in FIG. 5a after the reforming process. [Figure 6] It is a cross-sectional view showing an unfolded state before the electrode assembly according to a second embodiment of the present invention is wound. [Figure 7] It is a cross-sectional view showing the state after the electrode assembly shown in FIG. 6 is wound up. [Figure 8] It is a cross-sectional view showing an enlarged view of the "D" region adjacent to the center side of the electrode assembly in FIG. 7. [Figure 9] It is a cross-sectional view of the electrode assembly according to the third embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement it. However, the present invention may be realized in various different forms and is not limited or restricted by the following embodiments.

[0022] To clearly explain the present invention, detailed descriptions of parts not related to the explanation or related known technologies that may unnecessarily obscure the gist of the present invention are omitted. In this specification, when attaching reference numerals to the components of each drawing, the same or similar reference numerals shall be attached to the same or similar components throughout the specification.

[0023] Also, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventors should interpret them in accordance with the meaning and concept that conform to the technical idea of the present invention, in accordance with the principle that they can appropriately define the concept of the terms in order to explain their invention in the best way.

[0024] A secondary battery including an electrode assembly according to the first embodiment FIG. 1 is a perspective view showing a secondary battery including an electrode assembly according to the first embodiment of the present invention, FIG. 2 is an exploded perspective view showing the unfolded state before the electrode assembly shown in FIG. 1 is wound up, and FIG. 3 is a cross-sectional view showing the unfolded state before the electrode assembly shown in FIG. 1 is wound up.

[0025] Referring to Figures 1 to 3, the secondary battery 10 according to the first embodiment of the present invention may include an electrode assembly 100 and a battery case 180. The electrode assembly 100 can be housed inside the battery case 180. The battery case 180 may include a battery can 182 and a cap assembly 181.

[0026] The battery casing 182 may include a housing 183 capable of accommodating the electrode assembly 100. Electrolyte can be injected into the housing 183 so that the electrode assembly 100 is completely immersed within the battery casing 182. The top of the battery casing 182 may be open to serve as an inflow passage for the electrode assembly 100. The battery casing 182 may be made of metal. For example, the battery casing 182 may be made of stainless steel.

[0027] The battery can 182 can be formed in a shape corresponding to the shape of the electrode assembly 100 in order to house the electrode assembly 100. For example, the battery can 182 can be formed in a cylindrical shape so as to house the electrode assembly 100 which is formed in the shape of a jelly roll.

[0028] The cap assembly 181 is mounted on the battery can 182 so as to cover the open top of the battery can 182 and can be coupled to the battery can 182. The cap assembly 181 can be made up of a safety vent, a current interruption element, a PTC (Positive Temperature Coefficient) element, and a top cap, which are sequentially stacked. The top cap is placed on top of the cap assembly 181 and coupled to it, and transmits the current generated from the secondary battery to the outside.

[0029] Either the battery canister 182 or the cap assembly 181 can be electrically connected to the first electrode tab 171 of the electrode assembly 100, and the remaining battery canister 182 or cap 181 can be electrically connected to the second electrode tab 172. For example, the cap assembly 181 can be electrically connected to the first electrode tab 171 by a welding process, and the bottom of the battery canister 182 can be electrically connected to the second electrode tab 172 by a welding process. In other examples, either the battery canister 182 or the cap assembly 181 can be electrically connected to both the first electrode tab 171 and the second electrode tab 172.

[0030] The electrode assembly 100 may be a power generation element capable of charging and discharging. The electrode assembly 100 forms a structure in which electrodes 130 and separators 160 are assembled and stacked alternately. The electrode assembly 100 can be formed in a form in which electrodes 130 and separators 160 are wound up. The electrode assembly 100 may have a structure in which the diameter expands radially in proportion to the winding rotation speed. In this case, the electrode assembly 100 can be wound up in a cylindrical shape around a winding central axis (C). As an example, the electrode assembly 100 may be a jelly roll-shaped electrode assembly in which a first electrode 110, a first separator 140, a second electrode 120, and a second separator 150 are sequentially stacked and wound up in a cylindrical shape.

[0031] The electrode 130 may include a first electrode 110 and a second electrode 120. One of the first electrode 110 and the second electrode 120 may be a positive electrode, and the other one of the first electrode 110 and the second electrode 120 may be a negative electrode. For example, the first electrode 110 may be a positive electrode and the second electrode 120 may be a negative electrode.

[0032] The first electrode 110 may include a first current collector 111 and a first active material layer 112 formed on at least one of the one or the other surface of the first current collector 111. For example, if the first electrode 110 is a positive electrode, the first current collector 111 may be made of an aluminum foil. The first active material layer 112 may be made of, for example, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or compounds and mixtures containing one or more of these.

[0033] A portion of the first electrode 110 may include at least one first blank portion 113 made of the first current collector 111, without the first active material layer 112. At least one first electrode tab 171 may be attached to the first blank portion 113 by means of welding or other methods. The first electrode tab 171 may be electrically connected to the first electrode 110. The first electrode tab 171 may be located on the winding outer casing (O) of the first electrode 110.

[0034] The second electrode 120 may include a second current collector 121 and a second active material layer 122 formed on at least one of the two faces of the second current collector 121. For example, if the second electrode 120 is the negative electrode, the second current collector 121 may consist of a foil containing copper (Cu) and / or nickel (Ni) material. The second active material layer 122 may consist of, for example, artificial graphite, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, silicon compounds, tin compounds, titanium compounds, or alloys thereof. The second active material layer 122 may contain, for example, non-graphite-based SiO (silica) or SiC (silicon carbide).

[0035] The second electrode 120 is formed to be longer than the first electrode 110, and the edge portion of the second electrode 120 where winding begins can be located closer to the winding center (C) than the edge portion of the first electrode 110 where winding begins. Here, the edge portion of the first electrode 110 may include at least one of the following: the side surface of the first electrode 110 where winding begins; a portion of the first and second surfaces of the first electrode 110 adjacent to the side surface of the first electrode 110 where winding begins; a corner where the side surface of the first electrode 110 where winding begins meets the first and second surfaces of the first electrode 110, respectively; a corner where the side surface of the first electrode 110 where winding begins meets an adjacent side surface; or a vertex where a corner of the side surface of the first electrode 110 where winding begins meets an adjacent corner.

[0036] A portion of the second electrode 120 may include at least one second blank portion 123 made of the second current collector 121, without the second active material layer 122. At least one second electrode tab 172 may be attached to the second blank portion 123 by means of welding or other means. The second electrode tab 172 may be electrically connected to the second electrode 120. At least one second electrode tab 172 may be located at the winding center (C) of the second electrode 120. As an example, the second electrode tab 172 may be located downwards toward the bottom surface of the housing 183 of the battery can 182, as shown in Figure 1, and the first electrode tab 171 may be located upwards toward the direction in which the cap assembly 181 is located. As another example, the first electrode tab 171 and the second electrode tab 172 may be located toward the battery can 182 or the cap assembly 181.

[0037] A protective tab 173 can be attached to at least one of the first electrode tab 171 and the second electrode tab 172. The protective tab 173 can mitigate the step formed by the electrode tabs 171 and 172 and prevent damage to the separator 160 facing the electrode tab 15.

[0038] The separator 160 separates the first electrode 110 and the second electrode 120, providing electrical insulation. The separator 160 may include a first separator 140 and a second separator 150. The first separator 140 can be interposed between the first electrode 110 and the second electrode 120. The second separator 150 can be laminated on the outside of the first electrode 110 or the second electrode 120. For example, when a laminate in which the first electrode 110, the first separator 140, the second electrode 120, and the second separator 150 are sequentially laminated is wound up, a jelly roll type electrode assembly 100 can be formed in which the second separator 150 is formed on the outermost surface.

[0039] The separator 160 may be, for example, a multilayer film made of polyethylene, polypropylene, or a combination thereof, or a polymer film for solid polymer electrolytes or gel-type polymer electrolytes such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride hexafluoropropylene copolymer.

[0040] The electrode assembly 100 according to the first embodiment of the present invention may include a protective member 200 located on the winding center (C) side of the winding outer casing (O). The protective member 200 may include a first protective member 210 and a second protective member 220.

[0041] The first protective member 210 can be positioned in solid form between the edge portion where winding of the first electrode 110 begins and the first separator 140 before the electrode assembly 100 is wound up. The first protective member 210 can be formed on the first separator 140, elongated in the width direction of the first separator 140. The first protective member 210 can be formed alongside at least one of the first electrode tab 171 and the second electrode tab 172 before the electrode assembly 100 is wound up.

[0042] The second protective member 220 can be positioned in solid form between the edge portion where winding of the first electrode 110 begins and the second separator 150 before the electrode assembly 100 is wound up. The second protective member 220 can be formed on the second separator 140, elongated in the width direction of the second separator 140. The second protective member 220 can be formed alongside at least one of the first electrode tab 171 and the second electrode tab 172 before the electrode assembly 100 is wound up.

[0043] At least one of the first protective member 210 and the second protective member 220 may include a thermoplastic resin. The first protective member 210 and the second protective member 220 may be formed from thermoplastic resins of the same or different materials. For example, at least one of the first protective member 210 and the second protective member 220 may include a hot-melt adhesive sheet that melts at a high temperature of 120°C to 140°C and returns to a solid state at a low temperature.

[0044] Figures 4a and 4b are enlarged cross-sectional views showing portions adjacent to the winding center (C) of the electrode assembly according to the first embodiment of the present invention. Referring to Figures 4a and 4b, the electrode assembly 100 may include a first electrode (or positive electrode) 110, a first separator 140, a second electrode (or negative electrode) 120, a second separator 150, and a protective member 200. The protective member 200 may be positioned in the space between each of the first separator 140 and the second separator 150 and the edge portion where winding of the first electrode 110 begins. After winding of the electrode assembly 100, the protective member 200 may have a shape corresponding to at least a portion of the space between each of the first separator 140 and the second separator 150 and the edge portion where winding of the first electrode 110 begins. The protective member 200 may include a first protective member 210 and a second protective member 220.

[0045] The first protective member 210 and the second protective member 220 can be melted in a high-temperature first manufacturing step after the electrode assembly 100 has been wound up. Because the molten first protective member 210 and the second protective member 220 are liquid, they can flow not only towards the winding center (C) of the electrode assembly 100 between the first separator 140 and the second separator 150, but also into the space between each of the first separator 140 and the second separator 150 and the first electrode 110. The molten first protective member 210 and the second protective member 220 can be solidified again in a low-temperature second manufacturing step. As a result, the first protective member 210 and the second protective member 220 can be formed not only to be in contact with each other between the first separator 140 and the second separator 150, but also into a portion of the space between each of the first separator 140 and the second separator 150 and the edge portion where the winding of the first electrode 110 begins. The first protective member 210 and the second protective member 220 can be formed to surround the side surface of the first active material layer 112 of the first electrode 110 and the side surface of the first current collector 111, which are included in the edge portion where the winding of the first electrode 110 begins.

[0046] After a low-temperature second manufacturing process, the first protective member 210 can be positioned between the edge portion of the first electrode 110 where winding begins and the first separator 140. The first protective member 210 can be formed on the first separator 140 to surround at least a portion of the edge portion of the first electrode 110 where winding begins. The first protective member 210 can be formed to surround the edge portion of the first electrode 110 that corresponds to the corner between the side surface of the first active material layer 112 facing the winding center (C) and one surface of the first active material layer 112 facing the first separator 140. The first protective member 210 can be formed to wind at least a portion of the edge portion of the first electrode 110 where winding begins at least once.

[0047] After the low-temperature second manufacturing process, the second protective member 220 can be positioned between the edge portion of the first electrode 110 where winding begins and the second separator 150. The second protective member 220 can be formed on the second separator 150 to surround at least a portion of the edge portion of the first electrode 110 where winding begins. The second protective member 220 can be formed to surround the edge portion of the first electrode 110 that corresponds to the corner between the side surface of the first active material layer 112 facing the winding center (C) and the other surface of the first active material layer 112 facing the second separator 150. The second protective member 220 can be formed to wind at least a portion of the edge portion of the first electrode 110 where winding begins at least once.

[0048] As an example, the first protective member 210 and the second protective member 220 can be formed to be separated from each other in a region adjacent to the edge of the first electrode 110, as shown in Figure 4a. At least one of the first protective member 210 and the second protective member 220 shown in Figure 4a can be formed to cover at least a portion of the side surface of the first active material layer 112, excluding the side surface of the first current collector 111 facing the winding center (C). At least one of the first protective member 210 and the second protective member 220 shown in Figure 4a can be formed to not contact the side surface of the first current collector 111 facing the winding center (C), but to contact the side surface of the first active material layer 112.

[0049] As another example, the first protective member 210 and the second protective member 220 can be formed to contact and integrate with each other in a region adjacent to the edge of the first electrode 110, as shown in Figure 4b. At least one of the first protective member 210 and the second protective member 220 shown in Figure 4b can be formed to cover the side surface of the first current collector 111 and the side surface of the first active material layer 112 facing the winding center (C). At least one of the first protective member 210 and the second protective member 220 shown in Figure 4b can be formed to contact the side surface of the first current collector 111 and the side surface of the first active material layer 112 facing the winding center (C).

[0050] In this way, the sharp edge of the first electrode 110 is covered via the first protective member 210 and the second protective member 220, thereby preventing the first separator 140 and the second separator 150 from being damaged by the edge of the first electrode 110.

[0051] On the other hand, the high-temperature first manufacturing process may be a part of the reform process or all of the reform process. For example, the high temperature may be between 120°C and 140°C. The low-temperature second manufacturing process may be a process performed at a lower temperature than the first manufacturing process. The second manufacturing process may be a process performed immediately after the first manufacturing process or after a predetermined time has elapsed since the completion of the first manufacturing process. The second manufacturing process may be a part of the reform process or a process performed after the reform process. The reform process may be a process in which, when the core (not shown) used during the winding of the electrode assembly 100 is removed from the electrode assembly 100, the first separator 140 and / or the second separator 150 that detach to the outside along with the core are returned to the winding center (C) of the electrode assembly 100.

[0052] Figure 5a shows a part of the protective member placed on the separator before winding of the electrode assembly according to the first embodiment of the present invention, and Figure 5b shows a part of the protective member placed on the separator shown in Figure 5a after the reform process. The separator 160 shown in Figures 5a and 5b may be at least one of the first separator 140 and the second separator 150 shown in Figures 4a and 4b, and the protective member 200 shown in Figures 5a and 5b may be at least one of the first protective member 210 and the second protective member 220 shown in Figures 4a and 4b.

[0053] As shown in Figure 5a, the protective member 200 of the electrode assembly before winding can be formed on the separator 160 to have a first transverse length (LH1), a first longitudinal length (LV1), and a first thickness (T1).

[0054] In a high-temperature first manufacturing process (e.g., a refurbishment process) after winding the electrode assembly, the protective member 200 can be melted into a liquid state. The molten liquid protective member 200 can expand into adjacent areas and flow into the voids 161 of the separator 160 that are in contact with the protective member 200. Subsequently, in a low-temperature second manufacturing process, the protective member 200 can solidify. As a result, the protective member 200 can solidify with a thinner thickness and a larger surface area than before the winding process, as shown in Figure 5b. That is, the protective member 200 after the high-temperature first manufacturing process can be formed to have a second transverse length (LH2) longer than the first transverse length (LH1), a second longitudinal length (LV2) longer than the first longitudinal length (LV1), and a second thickness (T2) thinner than the first thickness (T1).

[0055] According to one embodiment, the separator 160 does not need to have a void formed in at least a portion of the region facing the electrode 130. In the high-temperature first step, it is possible to prevent conductive material contained in the electrode 130 from flowing into the void of the separator 160.

[0056] According to one embodiment, the separator 160 may include a plurality of voids 161 formed near the area facing the protective member 200. After a portion of the liquid protective member 200 flows into the voids of the separator 160 and solidifies, the voids 161 of the separator 160 can be filled with the protective member 200. As a result, the region of the separator 160 that is in contact with the protective member 200 can be formed to be more rigid than the region that is not in contact with the protective member 200. The region of the separator 160 located near the winding center (C) of the electrode assembly 100 may be more rigid than the region located near the winding outer casing (O) of the electrode assembly 100. Near the winding center (C) of the electrode assembly 100, the highly rigid separator 160 and protective member 200 allow the winding center (C) of the electrode assembly 100 to easily maintain a circular shape. As a result, it is possible to prevent internal short circuits from occurring during the charge-discharge cycle of the secondary battery including the electrode assembly 100, thereby ensuring safety.

[0057] Electrode assembly according to the second embodiment Figure 6 is a cross-sectional view showing the unfolded state of the electrode assembly according to the second embodiment of the present invention before it is wound up. Figure 7 is a cross-sectional view showing the state after the electrode assembly shown in Figure 6 has been wound up, with the first separator and second separator shown in Figure 6 omitted. Figure 8 is an enlarged cross-sectional view showing the portion (D) adjacent to the center side of the electrode assembly in Figure 7.

[0058] The electrode assembly according to the second embodiment of the present invention has the same components as the electrode assembly according to the first embodiment of the present invention shown in Figures 1 to 5b, except for the protective member. Accordingly, a detailed explanation of the same components will be provided by following the explanation in Figures 2 to 5b.

[0059] Referring to Figures 6 to 8, the electrode assembly according to the second embodiment of the present invention may include a first protective member 210 and a second protective member 220. At least one of the first protective member 210 and the second protective member 220 can be formed to be wound at least once between the winding outer casing (O) and the edge portion where winding of the first electrode 110 begins. The first protective member 210 and the second protective member 220 can be formed to surround at least a portion of the edge portion where winding of the first electrode 110 begins. The first protective member 210 and the second protective member 220 can be formed to wind at least once over the edge portion where winding of the first electrode 110 begins. In this way, the sharp edge portion of the first electrode 110 is covered via the first protective member 210 and the second protective member 220, preventing the first separator 140 and the second separator 150 from being damaged by the edge portion of the first electrode 110.

[0060] At least one of the first protective member 210 and the second protective member 220 can extend toward the winding center (C) of the electrode assembly 100 in a region adjacent to the edge of the first electrode 110. At least one of the first protective member 210 and the second protective member 220 can be formed to overlap with the second electrode tab 172 before the electrode assembly 100 is wound up. For example, the first protective member 210 can be formed to overlap with the second electrode tab 172 before the electrode assembly is wound up.

[0061] At least one of the first protective member 210 and the second protective member 220 can be wound at least once between the winding center (C) and the edge portion where winding of the first electrode 110 begins. At least one of the first protective member 210 and the second protective member 220 can be positioned near the winding center (C) where the blank portion 123 consisting of the second current collector 121 of the second electrode 120 is located. At least one of the first protective member 210 and the second protective member 220 can be positioned between the first separator 140 and the second separator 150 near the winding center (C).

[0062] The first protective member 210 and the second protective member 220 can be formed to wind the winding center (C) of the electrode assembly at least once. They can be positioned to wind the blank portion 123 consisting of the second current collector 121 of the second electrode 120 at least once. Near the winding center (C) of the electrode assembly, the rigid first separator 140 and second separator 150, along with the first protective member 210 and the second protective member 220, can easily maintain the circular shape of the winding center (C) of the electrode assembly. This prevents internal short circuits from occurring during the charge-discharge cycle of the secondary battery including the electrode assembly, thereby ensuring safety.

[0063] Electrode assembly according to the third embodiment Figure 9 is a cross-sectional view of an electrode assembly according to the third embodiment of the present invention. Figure 9 is a diagram showing a part of the electrode assembly according to the third embodiment, corresponding to Figure 3.

[0064] The electrode assembly according to the third embodiment of the present invention has the same components as the electrode assembly according to the first embodiment of the present invention shown in Figures 1 to 5b, except for the protective member. Accordingly, a detailed explanation of the same components will be provided by following the explanation in Figures 2 to 5b.

[0065] Referring to Figure 9, the electrode assembly according to the third embodiment of the present invention may be attached to only one of the first separator and the second separator. Figure 9 shows the protective member attached only to the second separator, but is not limited to this. That is, the protective member may be formed in a manner that it can be attached only to the first separator, or in a manner that it can be attached only to the second separator. If necessary, the protective member can be attached to only one of the first separator and the second separator.

[0066] Depending on the electrode shape and the formation conditions of the electrode assembly, if it is not necessary to attach protective members to both the first and second separators, there is no need to deliberately attach them to both the first and second separators, which would result in material waste and a decrease in production efficiency. Therefore, it is possible to prevent material waste and a decrease in production efficiency by attaching them to only one of the first or second separators.

[0067] The secondary battery, including the aforementioned electrode assembly, can be applied to a variety of devices. While it can be applied to transportation methods such as electric bicycles, electric vehicles, and hybrids, it is not limited to these; it can be applied to a wide range of devices where battery modules are available.

[0068] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible by persons with ordinary skill in the art to which the present invention pertains, within a scope equivalent to the technical concept of the present invention and the claims described later. [Explanation of Symbols]

[0069] 100: Electrode assembly 110: 1st electrode 120: 2nd electrode 140: First separator 150: Second separator 171, 172: Electrode tabs 210: First protective member 220: Second protective member

Claims

1. An electrode assembly formed by winding together a first electrode, a first separator, a second electrode, and a second separator, The system includes a protective member disposed in the space between each of the first separator and the second separator and the edge portion where winding of the first electrode begins, and having a shape corresponding to at least a portion of the space, The protective member is an electrode assembly that includes a hot-melt adhesive sheet that melts and returns to a solid state.

2. The protective member is The electrode assembly according to claim 1, which is arranged to surround the edge portion where winding of the first electrode begins at least once.

3. The first electrode is First current collector, and The first active material layer is disposed on the first current collector, The protective member is The electrode assembly according to claim 1, formed so as to surround the side surface of the first current collector and the side surface of the first active material layer included in the first electrode.

4. The protective member is The electrode assembly according to claim 3, which contacts the side surface of the first current collector and the side surface of the first active material layer toward the winding center.

5. The protective member is A first protective member is disposed between the first separator and the edge portion where the winding of the first electrode begins, and The electrode assembly according to claim 1, further comprising a second protective member disposed between the second separator and the edge portion where winding of the first electrode begins.

6. A portion of the first protective member and a portion of the second protective member are The electrode assembly according to claim 5, wherein the electrodes are arranged to be in contact with each other between the first separator and the second separator.

7. At least one of the first protective member and the second protective member is The electrode assembly according to claim 5, wherein the plain portion of the second electrode is arranged to be wound at least once.

8. At least one of the first protective member and the second protective member is The electrode assembly is wound at least once between the winding center and the edge portion where the winding of the first electrode begins. The electrode assembly according to claim 5, wherein the electrode assembly is wound at least once between the winding outer casing of the electrode assembly and the edge portion where winding of the first electrode begins.

9. At least one of the first separator and the second separator is The electrode assembly according to claim 1, wherein the region in contact with the protective member has higher rigidity than the region not in contact with the protective member.

10. At least one of the first separator and the second separator includes a plurality of voids formed near the area facing the protective member, A part of the aforementioned protective member is The electrode assembly according to claim 1, wherein it is located within the gap of at least one of the first separator and the second separator.

11. The electrode assembly according to claim 1, wherein the protective member is formed from a thermoplastic resin.

12. The electrode assembly according to claim 1, wherein the protective member is attached to only one of the first separator and the second separator.

13. A secondary battery comprising an electrode assembly according to any one of claims 1 to 12.

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