Electrode assembly and secondary battery including 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 contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[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 technology]

[0003] In recent years, the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased dramatically, and as the development of electric vehicles, energy storage batteries, robots, satellites, and other devices has progressed in earnest, much research has been conducted on secondary batteries used as the driving power source for these products.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries depending on the shape of the battery case. The electrode assembly attached inside the battery case is a chargeable and dischargeable power generating element consisting of a laminated structure of electrodes and separators.

[0005] When a secondary battery including such an electrode assembly is repeatedly charged and discharged, swelling of the electrode assembly may occur, causing deformation of the wound center of the electrode assembly. If the wound center of the electrode assembly is deformed and loses its circular shape, an internal short circuit or disconnection may occur during the charge and discharge cycles, significantly reducing safety. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide an electrode assembly and a secondary battery including 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 will be apparent to those skilled in the art 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 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.

[0009] According to an embodiment, the protective member may be disposed to surround the edge portion where the winding of the first electrode starts 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 may be formed to surround a side surface of the first current collector and a side surface of the first active material layer included in the first electrode.

[0010] According to one embodiment, the protective member may contact a side of the first current collector facing the winding center and a side of the first active material layer. 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 each of the first and second protective members may be disposed between the first and second separators so as to be in contact with each other.

[0012] According to an embodiment, at least one of the first protective member and the second protective member may be arranged to wrap around the uncoated 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 may be wound at least once between a winding center of the electrode assembly and an edge portion where winding of the first electrode begins, and may be wound at least once between a winding outer periphery of the electrode assembly and an 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 that contacts the protection member that is higher in rigidity than a region that does not contact the protection member.

[0015] According to one embodiment, at least one of the first separator and the second separator includes a plurality of voids formed in a vicinity facing the protective member, and a portion of the protective member may be positioned within the void of at least one of the first separator and the second separator.

[0016] According to one embodiment, the protective member may be made of a thermoplastic resin. According to one embodiment, the protective member may include a hot melt adhesive sheet that melts at a high temperature and returns to a solid state at a low temperature.

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

[0018] According to an embodiment of the present invention, the electrode assembly may include a protective member disposed between the separator and an edge portion where winding of the positive electrode begins. The protective member and the separator prevent cracks in the negative electrode at the portion in contact with the edge portion of the positive electrode, thereby preventing disconnection and short circuit, thereby improving the safety of the secondary battery.

[0019] Furthermore, according to an embodiment of the present invention, the protective member and the separator can easily maintain the circular shape of the wound center of the electrode assembly, thereby preventing the occurrence of an internal short circuit during charge / discharge cycles of a secondary battery including the electrode assembly and ensuring safety. In addition, this document can provide various other benefits that can be perceived directly or indirectly. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view showing a secondary battery including an electrode assembly according to a first embodiment of the present invention; [Figure 2] 2 is an exploded perspective view showing the electrode assembly shown in FIG. 1 in an unfolded state before being wound up. FIG. [Figure 3] 2 is a cross-sectional view showing the electrode assembly shown in FIG. 1 in an unfolded state before being wound up. [Figure 4a] 3 is an enlarged cross-sectional view showing an example of a portion adjacent to the winding center (C) of the electrode assembly according to the first embodiment of the present invention. FIG. [Figure 4b] FIG. 4 is an enlarged cross-sectional view showing another example of a portion adjacent to the winding center portion (C) of the electrode assembly according to the first embodiment of the present invention. [Figure 5a] 3 is a view showing a part of a protective member disposed on a separator before winding of the electrode assembly according to the first embodiment of the present invention. FIG. [Figure 5b] 5b shows a portion of a protective member placed on the separator shown in FIG. 5a after a reforming process. [Figure 6] FIG. 6 is a cross-sectional view showing an electrode assembly according to a second embodiment of the present invention in an unfolded state before being wound up. [Figure 7] 7 is a cross-sectional view showing the electrode assembly shown in FIG. 6 after being wound up. FIG. [Figure 8] 8 is an enlarged cross-sectional view showing a region "D" adjacent to the center of the electrode assembly in FIG. 7. FIG. [Figure 9] FIG. 10 is a cross-sectional view of an electrode assembly according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand and practice the preferred embodiments of the present invention. However, the present invention may be embodied in various different forms and is not limited to the following embodiments.

[0022] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may unnecessarily obscure the gist of the present invention will be omitted, and in this specification, when assigning reference symbols to components in each drawing, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0023] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

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

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

[0026] The battery can 182 may include a receiving portion 183 capable of receiving the electrode assembly 100. An electrolyte may be poured into the receiving portion 183 so that the electrode assembly 100 is completely immersed in the battery can 182. The top of the battery can 182 may be open so that it can be used as an inlet passage for the electrode assembly 100. The battery can 182 may include metal. For example, the battery can 182 may include stainless steel.

[0027] The battery can 182 may be formed in a shape corresponding to the shape of the electrode assembly 100 to accommodate the electrode assembly 100. For example, the battery can 182 may be formed in a cylindrical shape to accommodate the electrode assembly 100 formed in a jelly roll shape.

[0028] The cap assembly 181 may be mounted on the battery can 182 to cover the open top of the battery can 182 and be coupled to the battery can 182. The cap assembly 181 may be formed by sequentially stacking a safety vent, a current interruption device, a PTC (Positive Temperature Coefficient) device, and a top cap. The top cap is mounted on and coupled to the top of the cap assembly 181 to transmit current generated from the secondary battery to the outside.

[0029] One of the battery can 182 and the cap assembly 181 may be electrically connected to the first electrode tab 171 of the electrode assembly 100, and the other of the battery can 182 and the cap 181 may be electrically connected to the second electrode tab 172. As an example, the cap assembly 181 may be electrically connected to the first electrode tab 171 by a welding process, and the bottom surface of the battery can 182 may be electrically connected to the second electrode tab 172 by a welding process. As another example, one of the battery can 182 and the cap assembly 181 may be electrically connected to the first electrode tab 171 and the second electrode tab 172.

[0030] The electrode assembly 100 may be a chargeable / dischargeable power generating element. The electrode assembly 100 has a structure in which electrodes 130 and separators 160 are assembled and alternately stacked. The electrode assembly 100 may be formed in a wound form in which the electrodes 130 and separators 160 are wound. The electrode assembly 100 may have a structure in which its diameter expands radially in proportion to the number of winding rotations. In this case, the electrode assembly 100 may be wound into a cylindrical shape around a winding central axis (C). For 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 into a cylindrical shape.

[0031] The electrodes 130 may include a first electrode 110 and a second electrode 120. Either 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 one side and the other side of the first current collector 111. For example, when 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 a compound or mixture containing one or more of these.

[0033] A portion of the first electrode 110 may include at least one first uncoated 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 uncoated portion 113 by a method such as welding. 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 portion (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 one side and the other side of the second current collector 121. For example, when the second electrode 120 is a negative electrode, the second current collector 121 may be made of a foil containing copper (Cu) and / or nickel (Ni). The second active material layer 122 may be made of, for example, artificial graphite, lithium metal, a lithium alloy, carbon, petroleum coke, activated carbon, graphite, a silicon compound, a tin compound, a titanium compound, or an alloy thereof. The second active material layer 122 may contain, for example, non-graphite-based silica (SiO) or silicon carbide (SiC).

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

[0036] A portion of the second electrode 120 may include at least one second uncoated 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 uncoated portion 123 by a method such as welding. The second electrode tab 172 may be electrically connected to the second electrode 120. The at least one second electrode tab 172 may be located at the winding center (C) of the second electrode 120. For example, as shown in FIG. 1 , the second electrode tab 172 may be located downward, toward the bottom surface of the receiving portion 183 of the battery can 182, and the first electrode tab 171 may be located upward, toward the direction in which the cap assembly 181 is located. For 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 protection tab 173 may be attached to at least one of the first electrode tab 171 and the second electrode tab 172. The protection tab 173 reduces the step formed by the electrode tabs 171 and 172 and can prevent damage to the separator 160 facing the electrode tab 171.

[0038] The separator 160 separates and electrically insulates the first electrode 110 and the second electrode 120. The separator 160 may include a first separator 140 and a second separator 150. The first separator 140 may be interposed between the first electrode 110 and the second electrode 120. The second separator 150 may be stacked on the outside of the first electrode 110 or the second electrode 120. For example, when a stack in which the first electrode 110, the first separator 140, the second electrode 120, and the second separator 150 are stacked in order is wound up, a jelly roll-type electrode assembly 100 may 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 a solid polymer electrolyte or a gel-type polymer electrolyte, 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 closer to the winding center portion C than the winding outer portion O. The protective member 200 may include a first protective member 210 and a second protective member 220.

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

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

[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 the same or different thermoplastic resin 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] 4a and 4b are enlarged cross-sectional views showing a portion adjacent to the winding center (C) of the electrode assembly according to the first embodiment of the present invention. 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 disposed 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 process after the electrode assembly 100 is wound. Because the molten first protective member 210 and the second protective member 220 are liquid, they can flow not only between the first separator 140 and the second separator 150 toward the winding center (C) of the electrode assembly 100 but also into the spaces between the first separator 140 and the second separator 150 and the first electrode 110, respectively. The molten first protective member 210 and the second protective member 220 can be solidified again in a low-temperature second manufacturing process. As a result, the first protective member 210 and the second protective member 220 can be formed not only so as to contact each other between the first separator 140 and the second separator 150 but also in some of the spaces between the first separator 140 and the second separator 150 and the edge where the winding of the first electrode 110 begins. The first protective member 210 and the second protective member 220 may be formed to surround the side of the first active material layer 112 of the first electrode 110 and the side of the first current collector 111 included in the edge portion where the winding of the first electrode 110 begins.

[0046] After the low-temperature second manufacturing process, the first protective member 210 may be disposed between the edge portion of the first electrode 110 where winding begins and the first separator 140. The first protective member 210 may be formed on the first separator 140 to surround at least a portion of the edge portion where winding of the first electrode 110 begins. The first protective member 210 may be formed to surround an edge portion of the first electrode 110 corresponding to a corner between a side 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 may be formed to wrap at least a portion of the edge portion where winding of the first electrode 110 begins at least once.

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

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

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

[0050] In this way, the sharp edges of the first electrode 110 are covered by the first protective member 210 and the second protective member 220, thereby preventing the edges of the first electrode 110 from damaging the first separator 140 and the second separator 150.

[0051] Meanwhile, the first manufacturing process at a high temperature may be a part of the reforming process or the entire reforming process. For example, the high temperature may be a temperature of 120°C to 140°C. The second manufacturing process at a low temperature may be a process performed at a temperature lower than that of the first manufacturing process. The second manufacturing process may be a process performed immediately after the first manufacturing process or a predetermined time after the completion of the first manufacturing process. The second manufacturing process may be a process performed after the reforming process or another part of the reforming process. The reforming process may be a process of returning the first separator 140 and / or the second separator 150, which have been released to the outside together with the winding core (not shown) used in winding the electrode assembly 100, to the winding center (C) of the electrode assembly 100 when the winding core is removed from the electrode assembly 100.

[0052] Fig. 5a is a view showing a portion of a protective member disposed on a separator before winding of an electrode assembly according to a first embodiment of the present invention, and Fig. 5b is a view showing a portion of a protective member disposed on the separator shown in Fig. 5a after a reforming process. Separator 160 shown in Fig. 5a and Fig. 5b may be at least one of first separator 140 and second separator 150 shown in Fig. 4a and Fig. 4b, and protective member 200 shown in Fig. 5a and Fig. 5b may be at least one of first protective member 210 and second protective member 220 shown in Fig. 4a and Fig. 4b.

[0053] The protective member 200 before winding of the electrode assembly can be formed on the separator 160 to have a first horizontal length (LH1), a first vertical length (LV1), and a first thickness (T1), as shown in FIG. 5a.

[0054] In a first manufacturing process (e.g., a reforming process) at high temperature after winding the electrode assembly, the protective member 200 can be melted into a liquid state. The molten liquid protective member 200 can expand to adjacent regions and flow into the gaps 161 of the separator 160 that contact the protective member 200. Then, in a second manufacturing process at low temperature, the protective member 200 can be solidified. As a result, the protective member 200 can be solidified with a thinner thickness and a larger surface area than before the winding process, as shown in FIG. 5b. That is, after the first manufacturing process at high temperature, the protective member 200 can be formed to have a second horizontal length (LH2) longer than the first horizontal length (LH1), a second vertical length (LV2) longer than the first vertical length (LV1), and a second thickness (T2) thinner than the first thickness (T1).

[0055] According to one embodiment, the separator 160 may not have voids in at least a portion of the region facing the electrode 130. This can prevent the conductive material contained in the electrode 130 from flowing into the voids in the separator 160 during the first process at high temperature.

[0056] According to one embodiment, the separator 160 may include a plurality of voids 161 formed near the area facing the protective member 200. A portion of the liquid protective member 200 may flow into the voids of the separator 160 and then solidify, thereby filling the voids 161 of the separator 160 with the protective member 200. As a result, the separator 160 may be formed such that the area in contact with the protective member 200 is more rigid than the area not in contact with the protective member 200. The separator 160 may have a region located near the winding center (C) of the electrode assembly 100 that is more rigid than a region located near the winding outer periphery (O) of the electrode assembly 100. The highly rigid separator 160 and protective member 200 near the winding center (C) of the electrode assembly 100 can easily maintain the circular shape of the winding center (C) of the electrode assembly 100. This prevents an internal short circuit from occurring during charge / discharge cycles of a secondary battery including the electrode assembly 100, thereby ensuring safety.

[0057] Electrode assembly according to a second embodiment Fig. 6 is a cross-sectional view showing an electrode assembly according to a second embodiment of the present invention in an unfolded state before being wound up. Fig. 7 is a cross-sectional view showing the electrode assembly shown in Fig. 6 in a state after being wound up, with the first and second separators shown in Fig. 6 omitted. Fig. 8 is a cross-sectional view showing an enlarged view of a portion (D) adjacent to the center side of the electrode assembly in Fig. 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 a protective member, and therefore, the detailed description of the same components will be the same as that of Figures 2 to 5b.

[0059] 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. In the electrode assembly according to the second embodiment of the present invention, a first protective member 210 and a second protective member 220 are provided. At least one of the first protective member 210 and the second protective member 220 may be formed to be wound at least once between the winding outer shell (O) and the edge portion where winding of the first electrode 110 begins. The first protective member 210 and the second protective member 220 may 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 may be formed to be wound at least once around 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 by 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 portion of the first electrode 110.

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

[0061] At least one of the first protective member 210 and the second protective member 220 may 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 may be disposed near the winding center (C) where the uncoated portion 123 made of the second current collector 121 of the second electrode 120 is disposed. At least one of the first protective member 210 and the second protective member 220 may be disposed 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 may be formed to wrap around the winding center portion (C) of the electrode assembly at least once. They may be arranged to wrap around the non-coating portion 123 consisting of the second current collector 121 of the second electrode 120 at least once. The highly rigid first separator 140 and second separator 150, and the first protective member 210 and second protective member 220 near the winding center portion (C) of the electrode assembly can easily maintain the circular shape of the winding center portion (C) of the electrode assembly. This can prevent internal short circuits from occurring during charge / discharge cycles of a secondary battery including the electrode assembly, ensuring safety.

[0063] Electrode assembly according to a third embodiment 9 is a cross-sectional view of an electrode assembly according to a third embodiment of the present invention, and corresponds to FIG. 3 and shows a part of the electrode assembly according to the third embodiment.

[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 a protective member. Therefore, the detailed description of the same components will be the same as that of Figures 2 to 5b.

[0065] Referring to Fig. 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. Although Fig. 9 shows the protective member attached to only the second separator, this is not limiting. That is, the protective member may be formed in a shape that is attached to only the first separator, or may be formed in a shape that is attached to only the second separator. If necessary, the protective member may be attached to only one of the first separator and the second separator.

[0066] If it is not necessary to attach a protective member to both the first separator and the second separator due to the shape of the electrodes or the conditions for forming the electrode assembly, there is no need to attach a protective member to both the first separator and the second separator, which would result in wasted material and reduced production efficiency.Therefore, it is possible to prevent wasted material and reduced production efficiency by attaching a protective member to only one of the first separator or the second separator.

[0067] The secondary battery including the electrode assembly described above can be applied to various devices, including, but not limited to, transportation means such as electric bicycles, electric cars, and hybrid vehicles, and can be applied to various devices that can use a battery module.

[0068] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the scope equivalent to the technical concept of the present invention and the claims that will be described later by a person having ordinary skill in the art to which the present invention pertains. [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 a first electrode, a first separator, a second electrode, and a second separator, 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 starts, the protective member having a shape corresponding to at least a part of the space; The electrode assembly, wherein the protective member includes a hot-melt adhesive sheet that melts at a high temperature and returns to a solid state at a low temperature.

2. The protective member is The electrode assembly according to claim 1 , wherein the first electrode is disposed so as to surround at least one edge portion from which winding of the first electrode begins.

3. The first electrode is a first current collector, and a first active material layer disposed on the first current collector; The protective member is The electrode assembly of claim 1 , wherein the first electrode is formed to surround a side surface of the first current collector and a side surface of the first active material layer.

4. The protective member is The electrode assembly according to claim 3 , wherein the first current collector and the first active material layer are in contact with each other on a side thereof facing the center of the winding.

5. The protective member is a first protective member disposed between the first separator and the edge portion where 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 each of the first protective member and the second protective member is The electrode assembly according to claim 5 , wherein the first separator and the second separator are disposed so as to be in contact with each other.

7. At least one of the first protective member and the second protective member is The electrode assembly according to claim 5 , wherein the uncoated portion of the second electrode is wound around the uncoated portion 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 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 outer winding portion and the edge portion where the winding of the first electrode starts.

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 is stiffer 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 in a vicinity facing the protective member, A part of the protective member is The electrode assembly according to claim 1 , wherein the electrode is located within a gap in at least one of the first separator and the second separator.

11. The electrode assembly according to claim 1 , wherein the protective member is made of 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 the electrode assembly according to any one of claims 1 to 12.

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