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 may include a protective member formed by winding a positive electrode, a separator, and a negative electrode, and disposed to face at least one end of the positive electrode and the negative electrode, and filled with a flame retardant inside.

Description

Technology Field

[0001] The present invention relates to an electrode assembly and a device including the same, and more specifically, to an electrode assembly capable of improving safety and a secondary battery including the same. Background Technology

[0002] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased rapidly, and the development of electric vehicles, energy storage batteries, robots, and satellites has accelerated, much research is being conducted on secondary batteries used as their power sources.

[0003] Secondary batteries are classified into coin batteries, cylindrical batteries, prismatic batteries, and pouch batteries according to the shape of the battery case. The electrode assembly mounted inside the battery case is a rechargeable power generation device consisting of a stacked structure of electrodes and separators.

[0004] When charge-discharge cycles of a secondary battery containing such an electrode assembly are repeatedly performed, swelling may occur, causing the center of the electrode assembly's winding to deform. If the center of the electrode assembly's winding fails to maintain a circular shape and becomes deformed, internal short circuits or open circuits may occur during the charge-discharge cycle, which can significantly reduce safety. The problem to be solved

[0005] An embodiment of the present invention aims to provide an electrode assembly capable of improving safety and a secondary battery including the same.

[0006] The technical problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by a person skilled in the art from the description below. means of solving the problem

[0007] An electrode assembly according to one embodiment of the present invention may include a protective member formed by winding an anode, a separator, and a cathode, positioned to face at least one end of the anode and the cathode, and filled with a flame retardant.

[0008] According to one embodiment, the protective member may face the electrode with the shorter length among the anode and cathode.

[0009] According to one embodiment, the protective member may be disposed on the separator so as to face the starting end where the winding of the anode begins.

[0010] According to one embodiment, the cathode includes an extended region that extends beyond the anode in a direction opposite to the winding direction of the electrode assembly, and the protective member may overlap with the extended region of the cathode.

[0011] According to one embodiment, the protective member may include a first insulating layer disposed on the separator and having a plurality of pores formed therein, into which the flame retardant is filled; a second insulating layer disposed on the first insulating layer and facing the center of the winding of the electrode assembly; and an adhesive layer disposed between the first insulating layer and the second insulating layer.

[0012] According to one embodiment, the second insulating layer may be thinner than the first insulating layer and may have a thickness greater than that of the adhesive layer.

[0013] According to one embodiment, the first insulating layer has a thickness of 50 to 70% of the total thickness of the protective member, the second insulating layer has a thickness of 20 to 30% of the total thickness of the protective member, and the adhesive layer may have a thickness of 10 to 20% of the total thickness of the protective member.

[0014] According to one embodiment, the second insulating layer may have a lower melting temperature than the first insulating layer.

[0015] According to one embodiment, the first insulating layer comprises at least one of polyimide (PI) and polyethylene terephthalate (PET), and the second insulating layer may comprise any one of polyethylene (PE), polypropylene (PP), and polyurethane (PU).

[0016] According to one embodiment, the first insulating layer comprises a first insulating region and a second insulating region disposed on both sides of the first insulating region, and the plurality of pores may be formed in the first insulating region excluding the second insulating region.

[0017] According to one embodiment, the flame retardant may be a flame-retardant liquid containing fluorine.

[0018] According to one embodiment, the positive electrode comprises a positive electrode current collector; a first active material layer disposed on top of the positive electrode current collector; and a second active material layer disposed on bottom of the positive electrode current collector, and the protective member may contact at least one end portion of the positive electrode current collector, the first active material layer, and the second active material layer.

[0019] According to one embodiment, the electrode assembly further comprises a cathode tab electrically connected to the cathode, and the protective member may have a width less than or equal to the distance between the end portion of the anode and the cathode tab.

[0020] According to one embodiment, the thickness of the protective member may be the same as the thickness of the anode.

[0021] According to one embodiment, the electrode assembly may further include a fire extinguishing agent filled inside the protective member.

[0022] A secondary battery according to one embodiment of the present invention may include the aforementioned electrode assembly. Effects of the invention

[0023] According to embodiments of the present invention, a protective member may be included that faces a winding end portion where the winding of the positive electrode begins in an electrode assembly. By preventing cracks in the negative electrode occurring at the portion in contact with the winding end portion of the positive electrode through this protective member, thereby preventing open circuits or short circuits, the safety of the secondary battery can be improved.

[0024] In addition, according to embodiments of the present invention, the center of the winding of the electrode assembly can be easily maintained in a circular shape through the protective member. Accordingly, safety can be ensured by preventing internal short circuits from occurring during the charge-discharge cycle of a secondary battery including the electrode assembly.

[0025] In addition, according to embodiments of the present invention, a filling member containing a flame retardant may be filled inside the protective member. By means of this protective member containing a flame retardant, it is possible to prevent a temperature rise of the secondary battery from leading to ignition or explosion.

[0026] In addition, various effects that can be identified directly or indirectly through this document may be provided. Brief explanation of the drawing

[0027] 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 illustrated in FIG. 1 in an unfolded state before being wound. FIG. 3 is a cross-sectional view showing the unfolded state of the electrode assembly illustrated in FIG. 1 before it is wound up. FIG. 4 is a plan view and a cross-sectional view showing a protective member according to the present invention. Figure 5 is a cross-sectional view showing an enlarged view of the periphery of the center of the winding after the electrode assembly shown in Figure 2 has been wound. FIG. 6 is a cross-sectional view showing the unfolded state of an electrode assembly according to a second embodiment of the present invention before being wound. Specific details for implementing the invention

[0028] 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.

[0029] 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.

[0030] 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.

[0032] A secondary battery comprising an electrode assembly according to the first embodiment

[0033] FIG. 1 is a perspective view showing a secondary battery including an electrode assembly according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view showing the electrode assembly shown in FIG. 1 in an unfolded state before being wound.

[0034] Referring to FIGS. 1 and FIGS. 2, a secondary battery (10) according to the present invention may include an electrode assembly (100) and a battery case (180).

[0035] An electrode assembly (100) may be accommodated within a battery case (180). The battery case (180) may include a battery can (182) and a cap assembly (181).

[0036] The battery can (182) may include a receiving portion (183) in which an electrode assembly (100) can be received. Electrolyte may be injected into the receiving portion (183) so that the electrode assembly (100) is completely immersed within the battery can (182). The top of the battery can (182) may be open so as to be used as an inflow passage for the electrode assembly (100). The battery can (182) may include metal. For example, the battery can (182) may include stainless steel.

[0037] Since the battery can (182) accommodates the electrode assembly (100), it can be formed in a shape corresponding to the shape of the electrode assembly (100). For example, the battery can (182) can be formed in a cylindrical shape so as to accommodate the electrode assembly (100) formed in a jelly-roll shape.

[0038] A cap assembly (181) can be mounted on a battery can (182) to cover the open top of the battery can (182) and combined with the battery can (182). The cap assembly (181) may be formed by sequentially stacking a safety vent, a current cutoff element, a positive temperature coefficient (PTC) element, and a top cap. The top cap is seated and combined on the top of the cap assembly (181) and transmits the current generated from the secondary battery to the outside.

[0039] Either one of the battery can (182) and the cap assembly (181) may be electrically connected to the positive 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 negative tab (172). For example, the cap assembly (181) may be electrically connected to the positive tab (171) through a welding process, and the bottom surface of the battery can (182) may be electrically connected to the negative tab (172) through a welding process. As another example, either one of the battery can (182) and the cap assembly (181) may be electrically connected to the positive tab (171) and the negative tab (172).

[0040] The electrode assembly (100) may be a power generation device capable of charging and discharging. The electrode assembly (100) forms 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 electrodes (130) and separators (160) are alternately assembled. The electrode assembly (100) may have a structure in which the diameter expands radially in proportion to the number of winding rotations. At this time, the electrode assembly (100) may be wound in a cylindrical shape centered on the winding center (or central axis) (C). For example, the electrode (130) may include a positive electrode (110) and a negative electrode (120), and the separator (160) may include a first separator (140) and a second separator (150). The electrode assembly (100) may be a jelly roll-shaped electrode assembly in which an anode (110), a first separator (140), a cathode (120), and a second separator (150) are sequentially stacked and wound into a cylindrical shape.

[0041] The positive electrode (110) may include a positive electrode current collector (113), a first positive electrode active material layer (111) formed on the outer surface (e.g., the surface facing the outer edge of the winding (O)) (123b) of the positive electrode current collector (113), and a second positive electrode active material layer (112) formed on the inner surface (e.g., the surface facing the center of the winding (C)) of the positive electrode current collector (113). The positive electrode current collector (113) may be formed to extend beyond at least one of the first positive electrode active material layer (111) and the second positive electrode active material layer (111) toward the outer edge of the winding (O). An area where the positive electrode current collector (113) is formed without at least one of the first positive electrode active material layer (111) and the second positive electrode active material layer (111) may be a positive electrode non-positive area (115). At least one anode tab (171) can be fused onto the anode current collector (113) of the anode non-positive portion (115) by means such as welding.

[0042] The positive current collector (113) may be made of, for example, an aluminum foil. At least one of the first positive active material layer (111) and the second positive 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 and mixture containing one or more of these.

[0043] The cathode (120) may include a cathode current collector (123), a first cathode active material layer (121) formed on the outer surface of the cathode current collector (123) (e.g., the surface facing the outer edge of the winding (O)), and a second cathode active material layer (122) formed on the inner surface of the cathode current collector (123) (e.g., the surface facing the center of the winding (C). The cathode (120) may be divided into a cathode coated portion (or retaining portion) and a cathode uncoated portion (or uncoated portion) (125) depending on the formation location of the first cathode active material layer (121) and the second cathode active material layer (122). The cathode coated portion may be an area where the first cathode active material layer (121) and the second cathode active material layer (122) are formed. The negative electrode unoccupied portion (125) may be an area where at least one of the first negative electrode active material layer (121) and the second negative electrode active material layer (122) is not formed. At least one negative electrode tab (172) may be fused onto the negative electrode current collector (123) of the negative electrode unoccupied portion (125) by a method such as welding.

[0044] The negative electrode current collector (123) may be made of a foil, for example, a copper (Cu) or / and nickel (Ni) material. At least one of the first negative electrode active material layer (121) and the second negative electrode active material layer (122) may be made of artificial graphite, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, silicon compound, tin compound, titanium compound, or an alloy thereof. At least one of the first negative electrode active material layer (121) and the second negative electrode active material layer (122) may contain, for example, non-graphite-based SiO (silica) or SiC (silicon carbide).

[0045] A separator (160) may be disposed between an anode (110) and a cathode (120) to separate the anode (110) and the cathode (120) and to electrically insulate them. The separator (160) may include a first separator (140) and a second separator (150). The first separator (140) may be laminated on the outside of either the anode (110) or the cathode (120). The second separator (150) may be laminated on the outside of the other of the anode (110) and the cathode (120). For example, when the first separator (140) is laminated on the outside of the anode (110), the first separator (140) may be disposed between the first anode active material layer (121) and the second cathode active material layer (112). When the second separator (150) is laminated on the outside of the cathode (120), the second separator (150) may be placed between the second positive active material layer (122) and the first negative active material layer (111). Meanwhile, when a laminate in which the positive electrode (110), the first separator (140), the cathode (120), and the second separator (150) are laminated in order is wound, a jelly roll type electrode assembly (100) in which the second separator (150) is formed on the outermost surface may be formed.

[0046] At least one of the first separator (140) and the second separator (150) may be a multilayer film made of, for example, 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.

[0047] The electrode assembly (100) according to the present invention may include a protective member (200) positioned to face at least one end of the anode (110) and the cathode (120). The protective member (200) may be positioned to face the end of the electrode with the shorter length among the anode (110) and the cathode (120). The protective member (200) may be located closer to the center of the winding (C) than to the outer edge of the winding (O). The protective member (200) may be formed long along the width direction of either the first separator (140) and the second separator (150). The protective member (200) may be formed parallel to at least one of the anode tab (171) and the cathode tab (172).

[0048] FIG. 3 is a cross-sectional view showing the unfolded state of the electrode assembly illustrated in FIG. 2 before it is wound. In FIG. 3, the positive electrode (110), the first separator (140), the negative electrode (120), and the second separator (150) are shown as being spaced apart, but after being wound, the positive electrode (110), the first separator (140), the negative electrode (120), and the second separator (150) can be in close contact with each other.

[0049] Referring to FIG. 3, the negative electrode (120) is formed to wrap around the positive electrode (110) during winding, so the negative electrode (120) may be formed longer than the positive electrode (110). The negative electrode (120) may include an extended region (126) that extends beyond the positive electrode (110) in the opposite direction to the winding direction (WD) of the electrode assembly. The winding direction (WD) may refer to the direction in which the negative electrode (120) and the positive electrode (110) are wound. In FIG. 3, the winding direction (WD) may be clockwise.

[0050] The protective member (200) overlaps with the extension region (126) of the cathode (120) and may be positioned to face the winding end portion (AE) of the anode (110). The protective member (200) may be positioned on the first separator (140) and may come into contact with the winding end portion (AE) of the anode (110). The protective member (200) may come into contact with at least one of the winding end portion (AE) of the first anode active material layer (111), the second anode active material layer (112), and the anode current collector (113).

[0051] The protective member (200) may be disposed on one side of the first separator (140) facing the center of the winding (C). The protective member (200) may have a thickness (T) corresponding to the anode (110). The thickness (T) of the protective member (200) may be the same as the thickness of the anode (110). For example, the thickness of the protective member (200) may be formed to be 90 μm to 150 μm, and the present invention does not limit the thickness of the protective member (200). Since the thickness of the anode (110) may vary from product to product depending on the product characteristics of the electrode assembly, the thickness of the protective member (200) may be formed to be the same as the anode depending on the product characteristics.

[0052] The protective member (200) may be formed to be wound from the winding start end (AE) of the anode (110) toward the winding center (C). The protective member (200) may extend from the winding start end (AE) of the anode (110) toward the winding center (C). In one example, the protective member (200) may be positioned between the winding start end (AE) of the anode (110) and the winding start end (CE) of the cathode (120). In another example, the protective member (200) may be positioned between the winding start end (AE) of the anode (110) and the cathode tab (172). The width (W) of the protective member (200) may have a size less than or equal to the distance (D) from the winding start end (AE) of the anode to the cathode tab (172). For example, the width (W) of the protective member (200) may be formed to be 10 mm to 21 mm. Meanwhile, a protective tab (173) may be attached to at least one of the negative tab (172) and the positive tab (e.g., the positive tab (171) of FIG. 1). The protective tab (173) can mitigate the step formed by the electrode tabs (171, 172) and prevent damage to the separator (140, 150) facing the electrode tabs (171, 172).

[0053] The protective member (200) can cover the step difference of the winding end portion (AE) of the positive electrode (110). The protective member (200) can eliminate the step difference of the winding end portion (AE) corresponding to the maximum thickness of the positive electrode (110). As the charging and discharging of the secondary battery proceeds, the negative electrode (120), which contracts and expands, may not be bent toward the winding end portion (AE) of the positive electrode (110) by the protective member (200). It is possible to prevent the negative electrode from coming into contact with the winding end portion (AE) of the positive electrode (110). Accordingly, since it is possible to prevent cracks from occurring in the first separator (140) by the winding end portion (AE) of the positive electrode (110), it is possible to prevent an electrical short circuit from occurring between the negative electrode (120) and the positive electrode (110).

[0054] In addition, through the protective member (200), the center of the coil (C) of the electrode assembly can easily maintain a circular shape. Accordingly, it is possible to prevent an internal short circuit from occurring during the charge / discharge cycle of the secondary battery containing the electrode assembly, thereby ensuring safety.

[0055] FIG. 4 is a plan view and a cross-sectional view showing a protective member according to the present invention, and FIG. 5 is a cross-sectional view showing an enlarged view of the area around the center of the winding (C) after the electrode assembly shown in FIG. 2 is wound.

[0056] Referring to FIGS. 4 and 5, the protective member (200) may be formed in the form of an insulating tape. The protective member (200) may include a first insulating layer (301), an adhesive layer (201), and a second insulating layer (302) that are sequentially laminated on one side of the first separator (140).

[0057] The adhesive layer (201) is disposed between the first insulating layer (301) and the second insulating layer (302) to bond the first insulating layer (301) and the second insulating layer (302). Additionally, the protective member (200) can be attached to the first separator (140) through the second adhesive layer (202). The second adhesive layer (202) can be disposed between the first insulating layer (301) and the first separator (140).

[0058] The first insulating layer (301) may include a first insulating region (310) and a second insulating region (320).

[0059] The first insulating region (310) may include a first surface (311), a second surface (312), and a third surface (313). The first surface (311) may be formed to face the center of the winding (C) (or the second insulating layer (302)). The second surface (312) may be formed to face in the opposite direction to the first surface (311) (or the second adhesive layer (202) or the first separator (140)). A plurality of third surfaces (313) may be arranged between the first surface (311) and the second surface (312). A plurality of third surfaces (313) may be formed to intersect the first surface (311) and the second surface (312).

[0060] The first insulating region (310) may include a plurality of pores (330). A first filling member (340) may be filled within the plurality of pores (330). For example, the first filling member (340) may be a flame-retardant liquid (or flame retardant) containing fluorine (F). The first filling member (340) in a liquid state may flow out of the protective member (200) when the secondary battery (e.g., the secondary battery (10) of FIG. 1) is in an abnormal operating state, such as an overcurrent state or a high temperature state. The first filling member (340) may flow out to the center of the winding (C) when the secondary battery (10) is in an abnormal operating state and cool the electrode assembly. The first filling member (340) can prevent the temperature rise of the secondary battery from leading to ignition or explosion.

[0061] The second insulating region (320) may be formed to surround a portion of the first insulating region (310). For example, the second insulating region (320) may be formed to surround a plurality of third surfaces (313), excluding the first surface (311) and the second surface (312) of the first insulating region (310). For another example, the second insulating region (320) may be formed to surround the second surface (312) and a plurality of third surfaces (313), excluding the first surface (311) of the first insulating region (310). The second insulating region (320) may serve to confine the first filling member (340) within the first insulating region (310) so that the first filling member (340) in a liquid state does not flow out when the secondary battery is in normal operating condition.

[0062] The first insulating region (310) and the second insulating region (320) may be formed from different materials or formed to be integrated with each other using the same material. At least one of the first insulating region (310) and the second insulating region (320) may be formed from a plastic material that exhibits electrical insulation. The first insulating region (310) and the second insulating region (320) may be formed from a material that does not easily melt at high temperatures, having a higher melting point than the second insulating layer (302). For example, the first insulating layer (301) including the first insulating region (310) and the second insulating region (320) may include at least one of polyimide (PI) and polyethylene terephthalate (PET).

[0063] The second insulating layer (302) may be placed on the adhesive layer (201) so as to face the center of the winding (C). The second insulating layer (302) may be placed closer to the center of the winding (C) than at least one of the adhesive layer (201) and the first insulating layer (301).

[0064] The second insulating layer (302) and the adhesive layer (201) can be formed to melt easily at high temperatures. For example, the second insulating layer (302) and the adhesive layer (201) can be formed to melt when the internal temperature of the secondary battery reaches 100 degrees Celsius or higher. As the second insulating layer (302) and the adhesive layer (201) melt at high temperatures, the flame retardant (340) inside the first insulating layer (301) can flow out to the outside of the protective member (200). The second insulating layer (302) can be formed from a material with a lower melting point than the first insulating layer (301). For example, the second insulating layer (302) may include any one of polyethylene (PE), polypropylene (PP), and polyurethane (PU).

[0065] The first insulating layer (301) included in the protective member (200) may be formed thicker than the adhesive layer (201) and the second insulating layer (302). The second insulating layer (302) may be formed with a thickness equal to or thicker than that of the adhesive layer (201). The thickness (T301) of the first insulating layer (301) may account for 50 to 70% of the total thickness of the protective member (200). The thickness (T302) of the second insulating layer (302) may account for 20 to 30% of the total thickness of the protective member (200). The thickness (T201) of the adhesive layer (201) may account for 10 to 20% of the total thickness of the protective member (200). Since the first insulating layer (301) is formed to be thicker than the adhesive layer (201) and the second insulating layer (302), the proportion of the first filling member (340) filled within the first insulating layer (301) in the protective member (200) can be increased. Accordingly, the temperature rise of the secondary battery can be prevented from leading to ignition or explosion by the protective member including the first filling member (340).

[0067] Electrode assembly according to the second embodiment

[0068] FIG. 6 is a cross-sectional view showing the unfolded state of an electrode assembly according to a second embodiment of the present invention before being wound.

[0069] 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 FIGS. 1 to 5b, except that a first filling member (340) and a second filling member (600) are filled within a plurality of pores (330). Accordingly, the detailed description of the same components is to be in accordance with the description in FIGS. 1 to 5.

[0070] Referring to FIG. 6, the protective member (200) may include a plurality of pores (330). A first filling member (340) may be filled in some of the plurality of pores (330). A second filling member (600) may be filled in the remainder of the plurality of pores (330). The first filling member (340) and the second filling member (600) may be formed from different materials. The first filling member (340) may include a flame-retardant liquid. As an example, the second filling member (600) may include a fire extinguishing agent (610). As another example, the second filling member (600) may be formed in a shape in which a shell (620) surrounds a core containing the fire extinguishing agent (610). Since the shell (620) melts upon ignition of the secondary battery, the fire extinguishing agent (610) contained in the core can be discharged toward the center of the coil (C). The fire extinguishing agent (610) contained in the second filling member (600) may not chemically react with the flame retardant contained in the first filling member (340).

[0071] The fire extinguishing agent (610) is discharged toward the center of the winding (C) when the secondary battery ignites, so as to suppress the fire in a short time and prevent the fire of the ignited electrode assembly (100) from spreading to adjacent electrode assemblies (100).

[0073] A secondary battery comprising the aforementioned electrode assembly can be applied to various devices. It can be applied to means of transportation such as electric bicycles, electric vehicles, and hybrids, but is not limited thereto and can be applied to various devices capable of using battery modules.

[0074] 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 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. Explanation of the symbols

[0075] 100: Electrode assembly 110: First electrode 120: Second electrode 140: First separator 150: Second separator 171,172: Electrode tabs 200: Absence of protection 340, 600: Filling member

Claims

Claim 1 An electrode assembly formed by winding an anode, a separator, and a cathode, comprising a protective member disposed to face at least one end of the anode and the cathode and filled with a flame retardant therein, wherein the protective member comprises: a first insulating layer disposed on the separator and having a plurality of pores formed therein filled with the flame retardant; a second insulating layer disposed on the first insulating layer and facing the center of the winding of the electrode assembly; and an adhesive layer disposed between the first insulating layer and the second insulating layer. Claim 2 In claim 1, the protective member is an electrode assembly facing the electrode with the shorter length among the positive and negative electrodes. Claim 3 In claim 1, the protective member is an electrode assembly disposed on the separator so as to face the starting end where the winding of the anode begins. Claim 4 In claim 1, the cathode includes an extended region extending beyond the anode in a direction opposite to the winding direction of the electrode assembly, and the protective member is an electrode assembly that overlaps with the extended region of the cathode. Claim 5 delete Claim 6 An electrode assembly according to claim 1, wherein the second insulating layer is thinner than the first insulating layer and has a thickness greater than or equal to that of the adhesive layer. Claim 7 An electrode assembly according to claim 1, wherein the first insulating layer has a thickness of 50 to 70% of the total thickness of the protective member, the second insulating layer has a thickness of 20 to 30% of the total thickness of the protective member, and the adhesive layer has a thickness of 10 to 20% of the total thickness of the protective member. Claim 8 In claim 1, the second insulating layer is an electrode assembly with a melting temperature lower than that of the first insulating layer. Claim 9 An electrode assembly according to claim 1, wherein the first insulating layer comprises at least one of polyimide (PI) and polyethylene terephthalate (PET), and the second insulating layer comprises any one of polyethylene (PE), polypropylene (PP), and polyurethane (PU). Claim 10 An electrode assembly according to claim 1, wherein the first insulating layer comprises a first insulating region and a second insulating region disposed on both sides of the first insulating region, and wherein the plurality of pores are formed in the first insulating region excluding the second insulating region. Claim 11 In claim 1, the electrode assembly is a flame retardant that is a flame-retardant liquid containing fluorine. Claim 12 In claim 1, the positive electrode comprises a positive current collector; a first active material layer disposed on the upper portion of the positive current collector; and a second active material layer disposed on the lower portion of the positive current collector, and the protective member is an electrode assembly in contact with at least one end portion of the positive current collector, the first active material layer, and the second active material layer. Claim 13 In claim 1, the electrode assembly further comprises a cathode tab electrically connected to the cathode, wherein the protective member has a width less than or equal to the distance between the starting end of the anode and the cathode tab. Claim 14 In claim 1, the electrode assembly in which the thickness of the protective member is the same as the thickness of the anode. Claim 15 An electrode assembly according to claim 1, further comprising a fire extinguishing agent filled inside the protective member. Claim 16 A secondary battery comprising an electrode assembly described in any one of claims 1 to 4 and claims 6 to 15.

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