Electrode tab for secondary battery, electrode assembly, secondary battery, battery pack, and transport device

Abstract

The present invention relates to an electrode tab for a secondary battery, in which the electrode tab comprises a first member and a second member, the first member and the second member have different electrical resistances, and the second member is located in at least a portion of the electrode tab, has an electrical resistance greater than that of the first member, and comprises a cut-off portion, the cut-off portion is thermally melted by its own resistance when an overcurrent of 10A or higher flows, thereby cutting off the current.

Description

Technical Field

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0073927 filed in the Korean Intellectual Property Office on June 9, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electrode tab for a secondary battery, an electrode assembly including the electrode tab, a secondary battery, a battery pack, and a mobile device. Background Art

[0003] Generally, a secondary battery refers to a rechargeable and dischargeable battery unlike a non-rechargeable primary battery, and the secondary battery is widely used in the field of high-tech electronic devices such as phones, notebook computers, and camcorders.

[0004] According to the shape of the battery case, secondary batteries are classified into: cylindrical batteries and prismatic batteries, in which the electrode assembly is embedded in a cylindrical or prismatic metal battery case; and pouch-type batteries, in which the electrode assembly is embedded in a pouch-type battery case made of an aluminum laminate sheet.

[0005] Typically, the materials used in secondary batteries (e.g., positive electrode active materials and negative electrode active materials, binders, electrolyte solutions, current collectors, etc.) are electrochemically stable at the voltage (2.5V to 4.3V) of battery operation. However, when the voltage of the battery is increased to a voltage higher than the operating voltage, the constituent materials decompose and produce gas at the corresponding decomposition voltage. The gas produced in this way increases the pressure inside the lithium secondary battery, and therefore, the voltage continues to increase. At this time, if there is a tiny short circuit or the lithium metal electrodeposited on the surface of the negative electrode infiltrates the separator and contacts the positive electrode, a large amount of current flows through the corresponding part, thereby promoting the generation of heat and gas. This heat and gas are released to the outside through the vulnerable part of the battery, thereby eventually causing the battery to catch fire or explode.

[0006] A cylindrical secondary battery may prevent fire or explosion of the secondary battery by forming notches in a current interrupt device (CID) and a safety vent included in a cap assembly so that heat and gas can be discharged to the outside by rupturing the CID and the safety vent.

[0007] However, the rupture of the CID and the safety vent is caused by the progress of gas generation inside the secondary battery. Therefore, if the reaction progresses rapidly, such as thermal runaway, the secondary battery may catch fire or explode before the rupture of the CID and the safety vent. Summary of the invention

[0008] Technical issues

[0009] In view of the above-mentioned situation of the related art, the present invention is made in an effort to provide an electrode tab for a secondary battery, which can prevent the secondary battery from catching fire and exploding by interrupting the current by utilizing heat generated by a large amount of current.

[0010] Technical Solution

[0011] An exemplary embodiment of the present invention provides an electrode tab for a secondary battery, the electrode tab comprising: a first member and a second member having different resistances, the second member being located in at least a portion of the electrode tab and having a resistance greater than that of the first member; and a cut-off portion configured to be melted by the resistance heat of the cut-off portion itself to interrupt the current when an overcurrent of 10 A or more flows.

[0012] An exemplary embodiment of the present invention provides an electrode assembly including the electrode tab.

[0013] An exemplary embodiment of the present invention provides a secondary battery including the electrode assembly.

[0014] An exemplary embodiment of the present invention provides a battery pack including the secondary battery.

[0015] An exemplary embodiment of the present invention provides a mobile device including the battery pack.

[0016] Beneficial Effects

[0017] The electrode tab for a secondary battery according to an exemplary embodiment of the present invention generally includes a material having a higher resistance than nickel, a nickel alloy, or aluminum that generally constitutes the electrode tab, so that when a large amount of current flows through the electrode tab, the electrode tab is cut off due to the material having a higher resistance to interrupt the current, thereby improving the safety of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a front view of an electrode tab according to an exemplary embodiment of the present invention.

[0019] Figure 2 are front views and side views of electrode tabs according to exemplary embodiments of the present invention, wherein (a) shows an electrode tab according to an exemplary embodiment, (b) shows an electrode tab according to another exemplary embodiment, (c) shows an electrode tab according to yet another exemplary embodiment, and (d) shows an electrode tab according to yet another exemplary embodiment.

[0020] Figure 3 is a cross-sectional view of a secondary battery including an electrode tab according to an exemplary embodiment of the present invention.

[0021] Figure 4 is a perspective view showing a battery pack including a secondary battery according to an exemplary embodiment of the present invention.

[0022] Figure 5 is a perspective view showing a mobile device including a battery pack according to an exemplary embodiment of the present invention.

[0023] [Explanation of Reference Numerals and Symbols]

[0024] 1: Secondary battery

[0025] 2: Shell assembly

[0026] 3: Battery Pack

[0027] 100: Electrode assembly

[0028] 10: Electrode contact

[0029] 11: Cut off part

[0030] 11a: First cut section

[0031] 11b: Second cut section

[0032] 12: Non-cutting part

[0033] 200: Battery box

[0034] 210: Curling part

[0035] 220: Crimping part

[0036] 300: Cover assembly

[0037] 310: Top cover

[0038] 320: Safety vent

[0039] 330: Current interrupting device

[0040] 340: Sealing gasket

[0041] 350: CID gasket

[0042] V: Mobile Device

[0043] C: Core DETAILED DESCRIPTION

[0044] The detailed description of the present invention is intended to fully explain the present invention to those skilled in the art. Throughout the entire specification, unless there is an explicit description to the contrary, when a component "includes (comprising)" another component or is "characterized by" having a certain structure and a certain shape, it means that other components, structures and shapes can be included without being excluded.

[0045] The present invention can be modified in various ways and can have various exemplary embodiments, and specific exemplary embodiments will be described in detail in the detailed description. However, the description of the exemplary embodiments is not intended to limit the content of the present invention, but it should be understood that the present invention will cover all modifications, equivalents and alternatives that fall within the spirit and technical scope of the present invention.

[0046] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, it should be noted that the accompanying drawings are provided for the purpose of illustrating the present invention, and the scope of the present invention is not limited by the accompanying drawings.

[0047] Figure 1 is a front view of an electrode tab according to an exemplary embodiment of the present invention, and Figure 2 1 is a front view and a side view of an electrode tab according to an exemplary embodiment of the present invention. Figure 2 , (a) shows an electrode tab according to an exemplary embodiment, (b) shows an electrode tab according to another exemplary embodiment, (c) shows an electrode tab according to yet another exemplary embodiment, and (d) shows an electrode tab according to yet another exemplary embodiment.

[0048] The electrode tab 10 according to the present invention includes a first member and a second member. The resistance of the first member is lower than the resistance of the second member. In other words, the resistance of the second member is greater than the resistance of the first member. Therefore, when a local short circuit occurs in the positive electrode or the negative electrode of the electrode assembly including the electrode tab 10 according to the exemplary embodiment of the present invention, the positive electrode and the negative electrode contact each other and a large amount of current flows through the contact portion, and the large amount of current cuts off the first member or the second member.

[0049] The second member may include a metal or non-conductor having a greater resistance than the first member. For example, the first member may include nickel, a nickel alloy, or aluminum. Preferably, the first member may include nickel or a nickel-copper alloy, and more preferably, nickel.

[0050] The second member may include a metal having a greater resistance than that of the first member, ie, a high resistance material, or a non-conductor. The high resistance material may include any one of lead, tin, zinc, copper and iron, and the non-conductor may include plastic or rubber.

[0051] In an exemplary embodiment, in the case where the second member is made of a high resistance material, when the temperature rises due to overcurrent, the temperature of the electrode tab 10 according to the exemplary embodiment of the present invention rises faster than the internal temperature of the battery due to the resistance heat of the second member itself and reaches the melting point, so that the electrode tab can be melted before the battery explodes or catches fire due to the increase in the internal temperature of the battery.

[0052] In other words, in the electrode tab 10 according to the exemplary embodiment of the present invention, the second member is melted so that the cross-sectional area of ​​the electrode tab 10 through which the current flows is reduced from the first member and the second member to the first member. Therefore, the resistance of the first member increases so that the first member is melted due to its own resistance heat and the resistance heat of the second member, thereby cutting off the electrode tab 10 and interrupting the current in the electrode tab 10.

[0053] In another exemplary embodiment, in the case where the second member is made of a non-conductor, current flows only through the first member of the electrode tab 10 according to the exemplary embodiment of the present invention, so that resistance and resistive heat in the first member increase when an overcurrent flows through the electrode tab 10. Therefore, the first member may be melted to interrupt the current in the electrode tab 10.

[0054] Therefore, the electrode tab 10 according to the exemplary embodiment of the present invention is cut off before the internal pressure of the secondary battery causes physical deformation in the CID or the safety vent due to heat and gas, thereby interrupting the flow of current, which increases the safety of the secondary battery.

[0055] Reference Figure 2 In (a), (c) and (d), the second member is located inside a portion of the electrode tab 10. In other words, most of the electrode tab 10 may be made of the first member, and the second member may be located in a portion of the electrode tab. Therefore, the second member may be surrounded by the first member, and the second member may not be exposed to the outside.

[0056] The electrode tab 10 may include a cut-off portion 11 which is melted by its own resistance heat to interrupt current when an overcurrent of 10A or more flows. The electrode tab 10 may include a non-cut-off portion 12 which is a portion other than the cut-off portion 11 .

[0057] Since the second member is located inside the electrode tab 10 , the cut-off portion 11 of the electrode tab 10 may include a structure in which the cut-off portion 11 includes the first member and the second member, and the first member is located on both surfaces of the second member.

[0058] The cut-off portion 11 may include one or two or more second members. The cut-off portion 11 may be disposed along the width direction of the electrode tab 10. In this case, the width direction of the electrode tab 10 refers to the direction of the length between two ends facing each other in a direction horizontal to the diameter of the electrode assembly.

[0059] When the cut-off portion 11 includes one second member, for example, the second member may be included in a long rectangular shape along the width direction of the electrode tab 10. The width of the second member may be narrower than the width of the electrode tab 10, and thus, the cut-off portion 11 may include a portion where only the first member is provided without including the second member.

[0060] When a large amount of current flows through the electrode assembly, the portion where only the first member is provided can be cut off by receiving heat from the portion including the second member 11, or can be easily cut off by the pressure caused by the gas generated inside the secondary battery. Therefore, safety can be ensured before a pressure sufficient to physically deform the secondary battery case, the CID, and the safety vent is reached.

[0061] When the cut-off portion 11 includes two or more second members, the second members may be positioned to be spaced apart from each other. For example, the cut-off portion 11 may include a plurality of first cut-off portions 11a formed by the second members and a second cut-off portion 11b in which only the first members are positioned and located between the first cut-off portions 11a, and the length of the first cut-off portion 11a and the length of the second cut-off portion 11b may be the same, and the width ratio may be 1:2 to 1:4.

[0062] Reference Figure 2 (b) and (c), the thickness of the cut portion 11 and the non-cut portion 12 of the electrode tab 10 may be different. For example, the thickness of the cut portion 11 may be 10% to 90% of the thickness of the non-cut portion 12. Preferably, the thickness of the cut portion 11 may be 20% to 90% of the thickness of the non-cut portion 12, and more preferably 30% to 80%.

[0063] exist Figure 2 In (c), the thickness of the first member of the cut-off portion 11 is thin, so that the overall thickness of the cut-off portion 11 is smaller than that of the non-cut-off portion 12. However, in the electrode tab 10 according to the exemplary embodiment of the present invention, the thickness of the second member of the cut-off portion 11 may be thin, thereby reducing the overall thickness of the cut-off portion 11.

[0064] In addition, since the thickness of the cut portion 11 is smaller than that of the non-cut portion 12 , the resistance of the cut portion 11 increases, which can facilitate melting and cutting of the cut portion 11 when an overcurrent flows through the electrode tab 10 , thereby facilitating current interruption of the electrode tab 10 .

[0065] The electrode tab 10 may include a first cut-off portion 11 a , a second cut-off portion 11 b , and a non-cut-off portion 12 .

[0066] For example, when the second cut-off portion 11b includes a second member made of a high-resistance material, the second cut-off portion 11b is melted and cut off by resistance heat, and after the second cut-off portion 11b is cut off, the first cut-off portion 11a is melted by its own resistance heat and the resistance heat of the second cut-off portion 11b, thereby causing the electrode tab 10 to be cut off.

[0067] Alternatively, when the second cut-off portion 11 b includes the second member made of a non-conductor, the first cut-off portion 11 a is melted and cut off by resistance heat, thereby causing the current of the electrode tab 10 to be interrupted.

[0068] The first cut-off portion 11 a may include only the second member, or may include the first member and the second member.

[0069] Reference Figure 2 (b), when the first cut-off portion 11a is formed only of the second member, the thickness of the second member may be 10% to 90% of the thickness of the non-cut-off portion 12. In this case, the second member of the electrode tab 10 for a secondary battery according to an exemplary embodiment of the present invention may be exposed to the first cut-off portion 11a.

[0070] Reference Figure 2 (c), when the first cut-off portion 11a is formed by the first member and the second member, the first member may be provided in a form located on both surfaces of the second member. The combined thickness of the second member and the first member located on both surfaces of the second member may be 10% to 100% of the thickness of the non-cut-off portion 12. Preferably, the combined thickness of the second member and the first member located on both surfaces of the second member may be 10% to 90% of the thickness of the non-cut-off portion 12.

[0071] In this case, the first member may be thinner than the second member, and the second member is not exposed to the outside. For example, if the thickness of the non-cut portion 12 is 50 μm to 300 μm, the thickness of the second member may be 40 μm to 250 μm, and the thickness of the first member located on one surface of the second member may be 10 μm to 50 μm.

[0072] Reference Figure 2 (d), the electrode tab 10 may have a second member additionally stacked at a position corresponding to the second member. That is, the electrode tab 10 may have one or more second members stacked or coated on one surface or both surfaces. The position of the second member to be stacked or coated may be the same as the position of the second member located inside the electrode tab 10.

[0073] In other words, the electrode tab 10 may include a cut-off portion 11 that is melted by its own resistance heat when an overcurrent of 10A or more flows to interrupt the current. The electrode tab 10 may include a cut-off portion 11 and a non-cut-off portion 12. That is, the electrode tab 10 may include a first cut-off portion 11a, a second cut-off portion 11b, and a non-cut-off portion 12. The first cut-off portion 11a may be formed by a first member and a second member, and a side end portion of the first cut-off portion 11a may be provided in a structure in which the first member is located between the second member.

[0074] The first cut-off portion 11a of the electrode tab 10 includes an inner second member located inside the electrode tab 10, a first member surrounding the inner second member, and an outer second member located on one surface of the first member corresponding to the inner second member. Therefore, the first cut-off portion 11a may be formed to be thicker than the non-cut-off portion 12 or the second cut-off portion 11b.

[0075] Since the second member is located inside and outside the first cut-off portion 11a, when an overcurrent flows through the secondary battery, the first member can easily reach a melting point due to the resistance heat of the second member located on both surfaces of the first member. In addition, by heating the first member on both surfaces of the first member, it is easy to interrupt the current before the internal temperature of the battery rises and causes the battery to explode or catch fire.

[0076] Figure 3 2 is a cross-sectional view of a secondary battery including an electrode tab according to an exemplary embodiment of the present invention. The secondary battery 1 includes an electrode assembly 100 , a battery case 200 , and a cap assembly 300 .

[0077] The electrode assembly 100 is a power generating element including a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode, and the power generating element can be charged and discharged.

[0078] The electrode assembly 100 may include a wound structure in which a first separator, a negative electrode, a second separator, and a positive electrode are sequentially stacked and wound.

[0079] The positive electrode may include a positive electrode current collector, a positive electrode active material portion, and a positive electrode uncoated portion. The positive electrode current collector is a metal thin plate having excellent electrical conductivity and may include, for example, aluminum (Al) foil.

[0080] The positive electrode is coated with a positive electrode active material on one or more of the two surfaces of the positive electrode current collector. The area coated with the positive electrode active material is the positive electrode active material portion, and the area not coated with the positive electrode active material is the positive electrode uncoated portion. Since the positive electrode uncoated portion is not applied with a positive electrode active material layer, the first electrode tab can be bonded to the positive electrode uncoated portion.

[0081] The positive electrode active materials may include: lithium cobalt oxide having high operating voltage and excellent capacity characteristics; lithium nickel oxide having high reversible capacity and used for easy realization of large-capacity batteries; lithium nickel cobalt oxide in which a portion of nickel is replaced by cobalt; lithium nickel cobalt metal oxide in which a portion of nickel is replaced by manganese, cobalt or aluminum; lithium manganese-based oxide having excellent thermal stability and low cost; lithium iron phosphate having excellent stability, etc.

[0082] The negative electrode may include a negative electrode current collector, a negative electrode active material portion, and a negative electrode uncoated portion. The negative electrode current collector may include a metal thin plate having excellent electrical conductivity, such as copper (Cu) or nickel (Ni) foil.

[0083] The negative electrode is coated with a negative electrode active material on one surface or both surfaces of the negative electrode current collector. The negative electrode active material portion is formed by coating or applying the negative electrode active material, and the negative electrode uncoated portion is an area where the negative electrode active material is not coated or applied and the negative electrode current collector is exposed. Since the negative electrode uncoated portion is not applied with the negative electrode active material, the second electrode tab can be bonded to the negative electrode uncoated portion.

[0084] The negative electrode active material may be, for example, a carbon material such as crystalline carbon, amorphous carbon, carbon composite material or carbon fiber, lithium metal, lithium alloy, etc. In this case, for high capacity design, the negative electrode active material may also include, for example, non-graphite-based SiO (silicon dioxide), SiC (silicon carbide), etc.

[0085] The first electrode tab and the second electrode tab are used to transfer the electrons collected in the current collector to the external circuit, and may protrude in opposite directions relative to the electrode assembly of the wound structure. The electrode tab according to an exemplary embodiment of the present invention includes one or more of the first electrode tab and the second electrode tab. That is, the first electrode tab and the second electrode tab may include a first member and a second member having different resistances, and the second member may be located inside a portion of the electrode tab.

[0086] The separator prevents an internal short circuit that may be generated when the positive electrode and the negative electrode contact each other, and the separator may include a porous material to facilitate migration of ions between the electrodes.

[0087] In an exemplary embodiment, the separator may include a substrate layer made of a porous material. The substrate layer may include, for example, any one selected from the group consisting of polyethylene (PE), polystyrene (PS), polypropylene (PP), and a copolymer of polyethylene (PE) and polypropylene (PP).

[0088] In another exemplary embodiment, the separator may include a safety reinforced separator (SRS). That is, the separator may include a substrate layer made of a porous material and a coating layer coated and formed on the substrate layer by applying a mixed slurry of inorganic particles and a binder polymer. Preferably, the coating layer includes ceramic particles and has a uniform pore structure formed by the interstitial volume between ceramic particles as components of the active layer in addition to the pore structure of the separator substrate itself.

[0089] The coating may include ceramic particles including at least one selected from the group consisting of alumina, silica, TiO2, SiC, and MgAl2O4. Including such a coating enables the safety of the electrode assembly to be enhanced. The coating may also include a lithium salt.

[0090] The battery case 200 may have a columnar structure in which a space is formed. The battery case 200 may accommodate an electrode assembly 100 including an electrode and a separator and an electrolyte solution (not shown) in the internal space. The battery case 200 may have a structure in which one side is open (hereinafter referred to as an opening portion) and the other side is sealed. Here, one side and the other side of the battery case 200 refer to end portions located at the upper portion and the lower portion along the gravity direction or the central axis of the battery case 200.

[0091] The opened upper side surface of the battery case 200 may be provided with a curling portion 210 folded toward the center of the secondary battery 1. The battery case 200 may be provided with a crimping portion 220 above the curling portion 210. That is, the crimping portion 220 may be positioned on the uppermost side of the battery case 200. Here, the upper portion refers to an area from the center of the battery case 200 toward the opening portion.

[0092] The battery case 200 may be made of a lightweight conductive metal material such as aluminum or an aluminum alloy.

[0093] The cover assembly 300 may be coupled to an open surface of the battery case 200 , and may include a top cover 310 , a safety vent 320 , and a current interruption device 330 .

[0094] The top cover 310 is positioned at the top of the cap assembly 300 and may protrude in a direction opposite to the center of the battery case 200. The top cover 310 may be used as an electrode terminal so that the protruding portion is electrically connected to the outside. For example, the top cover 310 may be used as a positive terminal.

[0095] The top cover 310 may be coupled with a sealing gasket 340 at an edge of the top cover 310, and the sealing gasket 340 may be positioned inside the crimping portion 220 of the battery case 200. The sealing gasket 340 may increase a sealing force between the top cover 310 and the battery case 200.

[0096] The top cover 310 may include a protrusion protruding upward, a rim portion contacting and coupled to the sealing gasket 340 , and a first connection portion connecting the protrusion and the rim portion.

[0097] The safety vent 320 is positioned below the top cover 310 and may be electrically connected to the top cover 310. At least a portion of a surface of the safety vent 320 facing the top cover 310 may be in contact with the top cover 310. The safety vent 320 contacts the top cover 310 for a certain length from an end portion thereof, and a portion other than the contact length may be located at a predetermined distance away from the top cover 310. The portion of the safety vent 320 contacting the top cover 310 may be coupled to the sealing gasket 340.

[0098] The spacing distance between the safety vent 320 and the top cover 310 may increase from the area where the safety vent 320 contacts the top cover 310 toward the center of the safety vent 320 .

[0099] The safety vent 320 may include a contact portion contacting the top cover 310, a central portion positioned at the center of the safety vent 320 and contacting the current interruption device, and a second connection portion connecting the contact portion and the central portion. The safety vent 320 may be provided with a bent portion (or notch) at portions where the contact portion and the second connection portion and the second connection portion and the central portion contact.

[0100] In an exemplary embodiment, the safety vent 320 may have an end portion perpendicular to the axial direction of the battery case 200. In this case, the top cover 310 may be disposed perpendicular to the axial direction of the battery case 200 like the safety vent 320. That is, the safety vent 320 and the top cover 310 may be positioned horizontally.

[0101] In another exemplary embodiment, the safety vent 320 may have an end portion bent to surround the outer peripheral surface of the top cover 310 .

[0102] In the secondary battery 1 according to the exemplary embodiment of the present invention, when the electrode assembly 100 accommodated inside the battery case 200 reacts with the electrolyte solution, gas is generated or heat is generated, thereby increasing the internal pressure.

[0103] When the internal pressure of the secondary battery 1 increases, the safety vent 320 receives a force in the direction of the top cover 310 , and the bent portion is broken, so that the gas inside the secondary battery 1 is discharged.

[0104] A current interrupt device (CID) 330 is positioned below the safety vent 320 , and at least a portion of the current interrupt device may be connected to the safety vent 320 .

[0105] When the safety vent 320 is ruptured as the internal pressure of the secondary battery 1 increases, the current interruption device 330 is separated from the safety vent 320 to interrupt the current.

[0106] More specifically, the current interruption device 330 may include a connection portion connected to the safety vent 320 at a central portion and protruding in a direction in which the safety vent 320 is positioned, an edge portion other than the connection portion, and a coupling portion connecting the connection portion and the edge portion. The coupling portion is provided in plural, and the plural coupling portions may be positioned to be spaced apart from each other.

[0107] When the safety vent 320 is deformed in the direction in which the top cover 310 is positioned, the coupling portion may be disconnected and the connection portion may be separated from the edge portion. That is, the connection portion is separated in the direction of the top cover 310 while being connected to the safety vent 320.

[0108] The CID gasket 350 surrounds the edge of the current interrupt device 330 , and can electrically separate the safety vent 320 from the edge portion and the coupling portion of the current interrupt device 330 excluding the connection portion.

[0109] According to an exemplary embodiment of the present invention, there is provided a battery pack including any one of the above-described secondary batteries.

[0110] Regarding the above exemplary embodiments, refer to Figure 4 , a battery pack 3 including a secondary battery 1 located in a pack case 2 is shown.

[0111] The battery pack according to the above exemplary embodiment has high output / high capacity.

[0112] According to an exemplary embodiment of the present invention, there is provided a mobile device including the above-mentioned battery pack.

[0113] Regarding the above exemplary embodiments, refer to Figure 5 , a mobile device V including a battery pack 3 is shown.

[0114] Since the mobile device according to the above exemplary embodiment uses a battery pack having high output / high capacity, the mobile device is excellent in stability and safety.

[0115] Although the present invention has been described with reference to preferred exemplary embodiments, it will be understood by those skilled in the art that various modifications and variations may be made to the present invention without departing from the technical spirit and scope of the present invention.

Claims

1. An electrode tab for a secondary battery, comprising: a first member and a second member, the first member and the second member having different resistances, the second member being located in at least a portion of the electrode tab and having a resistance greater than that of the first member; as well as A cut-off portion configured to be melted by resistance heat of the cut-off portion itself to interrupt the current when an overcurrent of 10 A or more flows.

2. The electrode tab for a secondary battery according to claim 1, wherein: The cut-off portion is configured by the first member, and the second member is located inside the first member.

3. The electrode tab for a secondary battery according to claim 2, wherein: The cut-off portion includes a first cut-off portion and a second cut-off portion, the first cut-off portion is a region where the second member is located, and the second cut-off portion is a region including only the first member, and Wherein, the cut-off portion includes one or two or more first cut-off portions.

4. The electrode tab for a secondary battery according to claim 3, wherein: Two or more of the first cut-off portions are positioned to be spaced apart from each other.

5. The electrode tab for a secondary battery according to claim 3, wherein: The first cut-off portion is disposed along a width direction of the electrode tab.

6. The electrode tab for a secondary battery according to claim 1, wherein: The electrode tab includes a non-cutting portion that is not cut off even when an overcurrent of 10 A or more flows, and The thickness of the cut-off portion is 10% to 90% of the thickness of the non-cut-off portion.

7. The electrode tab for a secondary battery according to claim 6, wherein: The cut-off portion is constituted by the first member, and the second member is located inside the first member.

8. The electrode tab for a secondary battery according to claim 6, wherein: The cut-off portion includes only the second member, and the non-cut-off portion includes only the first member.

9. The electrode tab for a secondary battery according to claim 2, wherein: The cut-off portion includes a second member additionally stacked on one surface of the first member. 10 . An electrode assembly comprising the electrode tab according to claim 1 . 11 . A secondary battery comprising the electrode assembly according to claim 10 .

12. A battery pack comprising the secondary battery according to claim 11.

13. A mobile device comprising the battery pack according to claim 12.

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