Secondary battery, and battery module and device including the same

Abstract

The present invention provides a secondary battery in order to improve the life and stability of the secondary battery by cutting off a current in an abnormal operating state of the secondary battery, the secondary battery comprising: an electrode assembly; an electrode current collector extending from the electrode assembly; the electrode tab is electrically connected with the electrode current collector; and a current cutoff member disposed between the electrode current collector and an electrode tab, the current cutoff member including: a first member connected to the electrode current collector and including a PTC element; and a second member connected to the electrode tab, the first member including a structure protruding upward in the direction of the electrode tab at or above a predetermined current value to be separated from the electrode current collector.

Description

Technical Field

[0001] The present invention relates to a secondary battery, a battery module and a device including the secondary battery, wherein the secondary battery includes a current cutoff component which is arranged between an electrode collector and an electrode tab and protrudes upward toward the electrode tab and is separated from the electrode collector in an abnormal working state. Background Art

[0002] The electric vehicle market requires batteries that can travel long distances on a single charge. A battery with high energy density can improve the driving range of electric vehicles. Lithium secondary batteries have high energy density and are therefore the most suitable batteries for electric vehicles.

[0003] Generally, a lithium secondary battery may be manufactured by housing an electrode assembly including electrodes that generate an electrical reaction in an outer package. Figure 1 A partial cross section of a secondary battery in which an existing electrode assembly is contained in an outer package is schematically shown. Figure 1 , the secondary battery 100 includes: an electrode assembly 10, which is contained in an outer package; an electrode current collector 11, which extends from the electrode assembly 10; and an electrode tab, which is electrically connected to the electrode current collector 11. When the secondary battery 100 is in normal working condition, there is no problem of internal gas generation, but in the abnormal working condition of the secondary battery 100, the overcurrent causes the internal temperature of the secondary battery 100 to rise sharply and the electrolyte to decompose, and the problem of diaphragm shrinkage occurs. In addition, due to the lithium plating phenomenon, dendrites are generated, so that the number of lithium ions is reduced and the risk of short circuit is increased, so the life and stability of the secondary battery are reduced. In particular, due to the heat, gas is continuously generated inside the secondary battery 100, so that the secondary battery 100 catches fire or explodes.

[0004] As described above, there is a need for a technology that can prevent secondary batteries from catching fire and exploding when they are in abnormal working conditions, thereby improving the life and stability of the secondary batteries. Summary of the invention

[0005] Technical issues

[0006] In order to improve the life and stability of a secondary battery, the present invention provides a secondary battery including a current cutoff component disposed between an electrode collector and an electrode tab and having a structure that protrudes upward toward the electrode tab and is separated from the electrode collector in an abnormal working state.

[0007] Technical Solution

[0008] The secondary battery according to the present invention includes: an electrode assembly; an electrode collector extending from the electrode assembly; an electrode tab electrically connected to the electrode collector; and a current cut-off component arranged between the electrode collector and the electrode tab, the current cut-off component including: a first component connected to the electrode collector and including a positive temperature coefficient (PTC) element; and a second component connected to the electrode tab, the first component including a structure that protrudes upward in the direction of the electrode tab and is separated from the electrode collector above a predetermined current value.

[0009] According to an embodiment, the current cutoff component may include a third component connected to the first component and the second component.

[0010] According to an embodiment, the current cutoff component may include: a first coupling portion connecting the first component and the third component; and a second coupling portion connecting the second component and the third component.

[0011] According to an embodiment, the first, second and third members may include a cross-section having a trapezoidal shape having upper and lower bases of different lengths.

[0012] According to an embodiment, the first, second and third members may include a cross-section having a trapezoidal shape in which the length of the lower base is greater than the length of the upper base.

[0013] According to an embodiment, the first coupling portion may connect a lower bottom of the first component and a lower bottom of the third component.

[0014] According to an embodiment, the second coupling portion may connect a lower bottom of the second component and a lower bottom of the third component.

[0015] According to an embodiment, in a case where the first member is separated from the electrode current collector, the connection between the first member and the third member may be maintained by the first coupling portion.

[0016] According to an embodiment, in a case where the first member is separated from the electrode current collector, the connection between the second member and the third member may be maintained by the second coupling portion.

[0017] According to an embodiment, in a case where the first member is separated from the electrode current collector, a gap may be formed between the electrode tab and the electrode current collector.

[0018] According to an embodiment, in a case where the internal temperature of the secondary battery is 80° C. or higher, the first member may be separated from the electrode current collector.

[0019] According to an embodiment, the PTC element may include a thermoplastic resin.

[0020] According to an embodiment, the PTC element may further include a carbon-based material and a ceramic material.

[0021] According to an embodiment, the secondary battery may include an outer package accommodating the electrode assembly and the electrode current collector, and the electrode tab may be led out from the outer package.

[0022] A battery module according to the present invention includes the secondary battery of the present invention.

[0023] The device according to the invention comprises the battery module according to the invention as a power source.

[0024] Effects of the Invention

[0025] The secondary battery according to the present invention includes a current cutoff member that cuts off current in an abnormal operation state, thereby having an effect of improving the life and stability of the secondary battery.

[0026] Moreover, the current cut-off component according to the present invention has a structure that protrudes downward in the direction of the electrode current collector under the normal working state of the secondary battery, and has a mobile structure that protrudes upward in the direction of the electrode tab and is separated from the electrode current collector under the abnormal working state of the secondary battery. Therefore, it has the effect of effectively guiding the short circuit between the electrode current collector and the electrode tab, and forming a gap between the electrode current collector and the electrode tab to prevent the possibility of current flow between the electrode current collector and the electrode tab.

[0027] Moreover, the current cutoff component according to the present invention forms a gap between the electrode collector and the electrode tab under abnormal operating conditions of the secondary battery, thereby effectively guiding the venting of gas generated inside the secondary battery, thereby having the effect of improving the life and stability of the secondary battery.

[0028] Furthermore, the current cutoff component according to the present invention is a structure that can be applied without changing the existing bonding structure of secondary battery materials such as the electrode assembly and the electrode tab, and has the effect of not requiring the outer packaging for accommodating the secondary battery to be changed or inserting another supporting structure.

[0029] Moreover, the current cut-off component according to the present invention is a structure that can be applied without changing the existing combination structure of secondary battery materials such as electrode assemblies and electrode tabs. Even if the secondary battery includes a current cut-off component, the appearance can be kept the same as that of previously mass-produced secondary batteries, and the assembly method of the battery module, battery pack, and device remains unchanged. Therefore, it has the effect of efficiently and economically manufacturing secondary batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A partial cross section of a secondary battery in which a conventional electrode assembly is contained in an outer package is briefly shown;

[0031] Figure 2 A secondary battery structure including a current cutoff component according to an embodiment of the present invention is briefly shown;

[0032] Figure 3 The structure of the current cutoff component is schematically shown, which protrudes upward toward the electrode tab to guide the short circuit between the electrode current collector and the electrode tab when an overcurrent occurs.

[0033] Description of Reference Numerals

[0034] 10, 20: Electrode assembly

[0035] 11, 21: Electrode current collector

[0036] 12, 22: Electrode tabs

[0037] 30: Current cut-off components

[0038] 31: First Part

[0039] 32: Second part

[0040] 33: The third component

[0041] 40: Outer packaging

[0042] 100, 200: Secondary battery DETAILED DESCRIPTION

[0043] The structural or functional descriptions of the embodiments disclosed in this specification or application are merely exemplary and are intended to illustrate the embodiments according to the technical ideas of the present invention. The embodiments according to the technical ideas of the present invention can be implemented in a variety of ways in addition to the embodiments disclosed in this specification or application, and should not be construed as limiting the technical ideas of the present invention to the embodiments described in this specification or application.

[0044] Hereinafter, the present invention will be described in detail.

[0045] The secondary battery according to the present invention includes: an electrode assembly; an electrode collector extending from the electrode assembly; an electrode tab electrically connected to the electrode collector; and a current cut-off component arranged between the electrode collector and the electrode tab, the current cut-off component including: a first component connected to the electrode collector and including a PTC element; and a second component connected to the electrode tab, the first component including a structure that protrudes upward in the direction of the electrode tab and is separated from the electrode collector above a predetermined current value.

[0046] Figure 2The structure of a secondary battery including a current cutoff component according to an embodiment of the present invention is briefly shown. Figure 2 The secondary battery 200 includes: an electrode assembly 20; an electrode current collector 21 extending from the electrode assembly; an electrode tab 22 electrically connected to the electrode current collector 21; and a current cutoff component 30 disposed between the electrode current collector 21 and the electrode tab 22.

[0047] The electrode assembly 20 may include a positive electrode, a negative electrode, and a structure of a separator layered between the positive electrode and the negative electrode. The positive electrode may include a positive electrode active material capable of embedding and desorbing lithium (Li) ions, and the negative electrode may include a negative electrode active material capable of absorbing and desorbing lithium (Li) ions. Moreover, the positive electrode and the negative electrode may also include a binder and a conductive material in the positive electrode active material and the negative electrode active material, respectively, to improve mechanical stability and conductivity. The separator may be configured to prevent an electrical short circuit between the positive electrode and the negative electrode and to generate an ion flow. The type of separator is not particularly limited, but may include a porous polymer film. The electrode assembly 20 may be manufactured by alternately stacking a plurality of positive electrodes and negative electrodes and providing a separator between the positive electrode and the negative electrode in a stacking or zigzag stacking manner.

[0048] The electrode current collector 21 is a plurality of positive current collectors and a plurality of negative current collectors extending from a plurality of positive electrodes and a plurality of negative electrodes, respectively, and the plurality of positive current collectors and a plurality of negative current collectors can be stacked and combined. A plurality of positive current collectors and a plurality of negative current collectors extending from a plurality of positive electrodes and a plurality of negative electrodes can extend from the electrode assembly 20 in the same direction or in different directions. The positive current collector is not particularly limited as long as it does not cause chemical changes in the positive electrode and has high conductivity. For example, stainless steel, aluminum, nickel, titanium, sintered carbon, etc. can be used. In addition, by forming tiny concave and convex on the surface of the positive current collector to increase the binding force of the positive active material, it can be manufactured into a variety of forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc. The negative current collector is particularly limited as long as it does not cause chemical changes in the negative electrode and has high conductivity. For example, copper, stainless steel, aluminum-cadmium alloy, etc. can be used. Moreover, like the positive electrode current collector, the negative electrode current collector may be provided with minute irregularities on its surface, or may be manufactured into various forms such as a film, a sheet, a foil, a net, a porous body, a foamed body, or a nonwoven fabric.

[0049] The electrode tab 22 is electrically connected to the electrode current collector 21. The electrode tab 22 may extend to the outside of the outer package 40 containing the electrode assembly 20 to become an electrode terminal. For example, the electrode tab electrically connected to the plurality of positive current collectors may become a positive terminal, and the electrode tab electrically connected to the plurality of negative current collectors may become a negative terminal. Figure 2The structure in which the electrode tab 22 is located on the upper part of the electrode current collector 21 is shown, but the structure in which the electrode tab 22 is located on the lower part of the electrode current collector 21 may also be used.

[0050] The current cutoff component 30 is disposed between the electrode current collector 21 and the electrode tab 22 . The current cutoff component 30 includes: a first component 31 connected to the electrode current collector 21 and including a PTC element; and a second component 32 connected to the electrode tab 22 .

[0051] The PTC (positive temperature coefficient) element includes a PTC material, which has the characteristic that the resistance value increases sharply with the temperature when an overcurrent is generated. The first component 31 includes a PTC element, so that the current flow between the electrode collector 21 and the electrode tab 22 can be cut off when an overcurrent is generated to prevent the overcurrent from causing the secondary battery to catch fire and explode.

[0052] The PTC element may include a polymer resin that acts as an electrical insulator, for example, the PTC element may include a thermoplastic resin. As the type of thermoplastic resin, it can be selected from the group consisting of high-density polyethylene, linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, maleic anhydride functionalized polyethylene, maleic anhydride functionalized elastomeric ethylene copolymers, ethylene-butene copolymers, ethylene-octene copolymers, ethylene-methyl acrylate, ethylene-ethyl acrylate and ethylene butyl acrylate copolymers, polyethylene including glycidyl methacrylate-modified polyethylene, polypropylene, maleic anhydride functionalized polypropylene, glycidyl methacrylate-modified polypropylene, polyvinyl chloride, polyvinyl acetate, polyvinyl acetyl, acrylic resin and alternating polystyrene.

[0053] Furthermore, the PTC element may further contain conductive fillers such as carbon-based materials and ceramic materials. BaTiO 3 , which can be found in BaTiO 3 Medium Mix Y 2 O 3 and Nb 2 O 5 use.

[0054] The current cut-off component 30 may include a third component 33 connected to the first component 31 and the second component 32. Furthermore, the current cut-off component 30 may include: a first joint portion 31-1 connecting the first component 31 and the third component 33; and a second joint portion 32-1 connecting the second component 32 and the third component 33. The current cut-off component 30 can ensure the mobility of the first component 31 and the third component 33 between the electrode collector 21 and the electrode tab 22 through the first joint portion 31-1 and the second joint portion 32-1. Therefore, the first component can be separated from the electrode collector by protruding upward in the direction of the electrode tab, and the current cut-off component can be applied even without changing the joint structure of the secondary battery elements such as the electrode assembly and the electrode tab or without inserting an additional supporting member, thereby having the effect of maintaining the same appearance as the secondary battery mass-produced in the past.

[0055] The first component 31, the second component 32, and the third component 33 may include a trapezoidal cross section having upper bases 31y, 32y, 33y and lower bases 31x, 32x, 33x of different lengths. Moreover, the first component 31, the second component 32, and the third component 33 may include a trapezoidal cross section having a lower base 31x, 32x, 33x of greater length than the upper base 31y, 32y, 33y. Preferably, the first joint 31-1 may be a connection between the lower base 31x of the first component and the lower base 33x of the third component, and the second joint 32-2 may be a connection between the lower base 32x of the second component and the lower base 33x of the third component. The first component, the second component and the third component include a trapezoidal cross-section and are connected to each other through a longer lower base in the trapezoidal shape, thereby allowing the first component to protrude upward toward the electrode tab when separated from the electrode current collector, and can effectively guide the short circuit between the electrode current collector and the electrode tab, thereby having the effect of preventing the possibility of electricity flowing between the electrode current collector and the electrode tab.

[0056] The first component is a structure that protrudes upward toward the electrode tab and is separated from the electrode current collector when the current value exceeds a predetermined value, wherein the predetermined current value refers to a threshold value at which the resistance value increases with the increase of the current to cut off the flow of the current through the PTC element.

[0057] Figure 3 The structure of the current cutoff component is schematically shown, which protrudes upward toward the electrode tab to guide the short circuit between the electrode current collector and the electrode tab when an overcurrent occurs.

[0058] Reference Figure 3In the normal working state of the secondary battery 200, the first component 31 is a structure that protrudes downward toward the electrode current collector 21. However, in the case of abnormal overcurrent in the secondary battery 200, the resistance of the PTC element included in the first component 31 increases, and the increased resistance causes the temperature and pressure inside the secondary battery 200 to increase, so the first component 31 protrudes upward toward the electrode tab 22 and separates from the electrode current collector 21.

[0059] Moreover, when the first component 31 is separated from the electrode current collector 21, the first component 31 and the third component 33 can be connected by the first bonding portion 31-1, and the second component 32 and the third component 33 can be connected by the second bonding portion 32-1. As a result, when the first component 31 is separated from the electrode current collector 21, a gap G can be formed between the electrode tab 22 and the electrode current collector 21, thereby effectively guiding the venting of gas generated inside the secondary battery to improve the life and stability of the secondary battery.

[0060] The first component 31 is a structure that protrudes upward in the direction of the electrode tab 22 and is separated from the electrode current collector 21 when the current value is above a predetermined value. When the internal temperature of the secondary battery 200 is above 80°C, the first component 31 can be separated from the electrode current collector 21. The first component 31 includes a PTC element, which includes a PTC material having a characteristic that the resistance value increases sharply as the temperature rises when an overcurrent is generated. Therefore, when the internal temperature of the secondary battery 200 is above 80°C, the characteristics of the PTC material can be manifested to function as a fuse that sharply increases the resistance and cuts off the current.

[0061] The secondary battery 200 includes an outer package 40 for accommodating the electrode assembly 20 and the electrode current collector 21, and the electrode tab 22 can be drawn out from the outer package 40. The outer package 40 plays a role in protecting the electrode assembly 20 from the external environment. The outer package 40 may contain a water-resistant resin, for example, it may be in the form of a film stacked with polyolefin resin, metal, nylon resin and polyterephthalate resin. According to the current cut-off component of the present invention, the current cut-off component can be applied even without changing the bonding structure of the secondary battery materials such as the electrode assembly and the electrode tab or without inserting another supporting member, so it has the effect of being applicable in the same form as the appearance of the existing secondary battery in which the electrode tab is drawn out from the outer package, without changing the outer package for accommodating the secondary battery.

[0062] The battery module according to the present invention includes the secondary battery of the present invention. More specifically, the battery module according to the present invention may include the secondary battery of the present invention as a unit cell. Moreover, the device according to the present invention includes the battery module of the present invention as a power source. The current cut-off component of the present invention is a structure that can be applied without changing the combination structure of existing secondary battery materials such as electrode assemblies and electrode tabs. Even if the current cut-off component is included in the secondary battery, the appearance of the secondary battery produced in mass production can be maintained in the same form, and the assembly method of the battery module and the device is not changed, so the battery module and the device can be manufactured efficiently and economically.

Claims

1. A secondary battery comprising: Electrode assembly; an electrode current collector extending from the electrode assembly; An electrode tab, electrically connected to the electrode current collector; as well as The current cut-off component is arranged between the electrode current collector and the electrode tab. The current cut-off component comprises: A first component connected to the electrode current collector and comprising a positive temperature coefficient element; as well as The second component is connected to the electrode tab, The first component includes a structure that protrudes upward toward the electrode tab and is separated from the electrode current collector when a predetermined current value is exceeded. 2 . The secondary battery according to claim 1 , wherein the current interruption component includes a third component connected to the first component and the second component.

3. The secondary battery according to claim 2, wherein the current cutoff component comprises: a first connecting portion, connecting the first component and the third component; as well as The second connecting portion connects the second component and the third component. 4 . The secondary battery according to claim 2 , wherein the first member, the second member, and the third member include a trapezoidal-shaped cross section having upper and lower bases of different lengths. 5 . The secondary battery according to claim 4 , wherein the first member, the second member, and the third member include a trapezoidal cross section in which a length of the lower base is greater than a length of the upper base. 6 . The secondary battery according to claim 5 , wherein the first coupling portion connects a lower bottom of the first member and a lower bottom of the third member. 7 . The secondary battery according to claim 5 , wherein the second coupling portion connects a lower bottom of the second member and a lower bottom of the third member. 8 . The secondary battery according to claim 3 , wherein in a case where the first member is separated from the electrode current collector, the first member and the third member are connected by the first bonding portion. 9 . The secondary battery according to claim 3 , wherein in a case where the first member is separated from the electrode current collector, the second member and the third member are connected by the second bonding portion. 10 . The secondary battery according to claim 1 , wherein when the first member is separated from the electrode current collector, a gap is formed between the electrode tab and the electrode current collector. 11 . The secondary battery according to claim 1 , wherein the first member is separated from the electrode current collector when the internal temperature of the secondary battery is 80° C. or higher. 12 . The secondary battery according to claim 1 , wherein the positive temperature coefficient element comprises a thermoplastic resin. 13 . The secondary battery according to claim 12 , wherein the positive temperature coefficient element further comprises a carbon-based material and a ceramic material. 14 . The secondary battery according to claim 1 , comprising an outer package accommodating the electrode assembly and the electrode current collector, the electrode tab being led out from the outer package. 15 . A battery module comprising the secondary battery according to claim 1 .

16. A device comprising the battery module according to claim 15 as a power source.

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