Top cap, cap assembly including same, and secondary battery

Abstract

The top cap of the present invention includes: a supply unit for supplying electricity to an external circuit; a terminal unit for supplying electricity to the supply unit; and an electrical blocking unit which electrically connects the supply unit and the terminal unit or releases the connection therebetween so as to cut off electricity in accordance with a deformation temperature, wherein the electrical blocking unit includes: an insulator provided between the supply unit and the terminal unit and separating the supply unit and the terminal unit from each other so that the supply unit and the terminal unit do not come into contact with each other; and a deformable body which electrically connects the supply unit and the terminal unit at a deformation temperature or lower, and releases the connection between the supply unit and the terminal unit so as to block the electricity therebetween while being deformed at the deformation temperature or higher.

Description

A top cap, a cap assembly including the top cap, and a secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0100647, filed August 1, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a top cap capable of improving safety by applying a shape memory alloy, a cap assembly including the top cap, and a secondary battery.

[0005] In general, secondary batteries are classified into cylindrical secondary batteries in which the electrode assembly is built into a cylindrical metal can, square secondary batteries in which the electrode assembly is built into a square metal can, and pouch-type secondary batteries in which the electrode assembly is built into a pouch-type case, depending on the shape of the battery case.

[0006] In addition, the electrode assembly is formed by a stacked structure of anode / separator / cathode, and such electrode assembly is classified into a jelly-roll type structure in which a separator is interposed between long sheet-shaped anodes and cathodes coated with active materials and wound, and a stack type structure in which a plurality of anodes and cathodes of a predetermined size are sequentially stacked with a separator interposed between them.

[0007] Among them, the jelly-roll type electrode assembly is the most widely manufactured because it has the advantages of being easy to manufacture and having a high energy density per weight, and the jelly-roll type electrode assembly is usually manufactured into a cylindrical secondary battery.

[0008] That is, the cylindrical secondary battery includes an electrode assembly, a can that accommodates the electrode assembly, and a cap assembly mounted in an opening of the can.

[0009] These cylindrical secondary batteries can undergo deformation as the jelly-roll electrode assembly undergoes repeated expansion and contraction during charging and discharging, potentially leading to internal short circuits. This can lead to heat generation from the internal short circuit, which can decompose the organic solvent, generating gas. This, in turn, can lead to an increase in gas pressure within the battery, potentially causing the battery to explode or rupture.

[0010] To solve the above problem, the cap assembly of the cylindrical secondary battery includes a safety vent for discharging high-pressure gas and a current interrupt device (CID) for interrupting current when the internal pressure of the secondary battery increases.

[0011] However, conventional cylindrical secondary batteries have limitations in increasing safety as their capacity increases, and therefore, structural improvements are needed to increase the safety of secondary batteries.

[0012] [Prior Art Literature]

[0013] [Patent Document]

[0014] Patent Publication No. 10-2018-0000115.

[0015]

[0016] The present invention aims to provide a top cap, a cap assembly including the same, and a secondary battery, which can rapidly cut off current when a high temperature occurs by including an electric cutoff section using a shape memory alloy applied to the top cap, thereby significantly improving safety.

[0017] The top cap of the present invention includes a supply unit that supplies electricity to an external circuit; a terminal unit that supplies electricity to the supply unit; an electrical cutoff unit that electrically connects the supply unit and the terminal unit or disconnects the supply unit and the terminal unit according to a deformation temperature, wherein the electrical cutoff unit may include an insulator provided between the supply unit and the terminal unit and spaced apart from contact between the supply unit and the terminal unit; and a deformation unit that electrically connects the supply unit and the terminal unit below a deformation temperature and disconnects the supply unit and the terminal unit from being electrically connected when deformed above the deformation temperature.

[0018] The above-mentioned deformation body can be made of a shape memory alloy that shrinks above a deformation temperature.

[0019] The above transformation temperature may be 70°C or higher.

[0020] The above-mentioned deformation body may have a shape that surrounds the outside of the insulator.

[0021] The above insulator may have a cylindrical shape, and the deformable body may have a circular ring shape surrounding the insulator.

[0022] One end of the above-described deformation body can be fixed to the supply portion or the terminal portion.

[0023] The height of the above electric cutoff part can be formed to be 2 mm to 12 mm.

[0024] The terminal portion includes a terminal surface that supplies electricity to the supply portion, and a coupling surface provided at a lower portion of the terminal surface and having a diameter larger than the terminal surface, and the supply portion and the electric blocking portion may have the same diameter as the terminal surface.

[0025] Meanwhile, a cap assembly according to a first embodiment of the present invention may include a top cap for supplying electricity to an external circuit; a safety element (Positive Temperature Coefficient element) provided at a lower portion of the top cap; a safety vent (Current Interrupt Device) provided at a lower portion of the safety element; a bottom cap provided at a lower portion of the safety vent; and a first insulator provided between the safety vent and the bottom cap.

[0026] The safety vent may include a first deformable body that electrically contacts the bottom cap below a deformation temperature and electrically separates from the bottom cap when deformed above the deformation temperature.

[0027] The above first deformable body can be made of a shape memory alloy that shrinks above a deformation temperature.

[0028] The first variant includes a contact portion protruding to contact the bottom cap and a non-contact portion not contacting the bottom cap, and a second insulator may be provided between the non-contact portion and the bottom cap.

[0029] The above safety vent may be provided on the upper surface of the first deformation body that does not face the bottom cap, and may further include a second deformation body having insulation.

[0030] The above second deformable body can be made of a shape memory polymer that does not deform below a deformation temperature and deforms above a deformation temperature.

[0031] Meanwhile, the secondary battery of the present invention may include a cap assembly including a top cap.

[0032] The top cap of the present invention includes a supply section, a terminal section, and an electrical cutoff section that electrically connects the supply section and the terminal section or electrically disconnects the supply section and the terminal section according to a deformation temperature, wherein the electrical cutoff section includes an insulator and a deformation body, so that the current can be quickly cut off when a high temperature occurs, thereby greatly improving safety.

[0033] In addition, in the top cap of the present invention, the deformable body is formed of a shape memory alloy that contracts at a temperature higher than the deformation temperature, so that the deformable body is quickly deformed by high temperature, and as a result, the supply part and the terminal part can be quickly separated, and as a result, electricity can be quickly cut off.

[0034] In addition, in the top cap of the present invention, the deformable body can increase the fixing force of the deformable body by having a shape that surrounds the exterior of the insulator. In particular, the deformable body can be freely movably coupled to the insulator, thereby preventing interference of the insulator when the deformable body is deformed.

[0035] In addition, in the top cap of the present invention, the insulator in the deformable body has a cylindrical shape, and the deformable body has a circular ring shape surrounding the insulator, thereby enabling the entire deformable body to be uniformly contracted.

[0036] In addition, in the top cap of the present invention, one end of the deformable body is fixed to the supply part or the terminal part, thereby preventing the movement of the deformable body and the resulting noise generation in advance.

[0037] FIG. 1 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention.

[0038] Figure 2 is a partially enlarged cross-sectional view of Figure 1.

[0039] Figure 3 is a perspective view showing a top cap according to the first embodiment of the present invention.

[0040] Figure 4 is a cross-sectional view of Figure 3.

[0041] Figure 5 is a cross-sectional view showing a contracted state of a secondary battery according to the first embodiment of the present invention.

[0042] Figure 6 is a cross-sectional view showing a safety vent of a secondary battery according to the first embodiment of the present invention.

[0043] Figure 7 is a cross-sectional view showing a state in which a safety vent of a secondary battery according to the first embodiment of the present invention is contracted.

[0044] Figure 8 is a perspective view showing a top cap according to a second embodiment of the present invention.

[0045] Figure 9 is a cross-sectional view showing a contracted state of a secondary battery according to a second embodiment of the present invention.

[0046] Hereinafter, embodiments of the present invention will be 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 implemented in various different forms and is not limited to the embodiments described herein. In addition, in the drawings, parts irrelevant to the description have been omitted to clearly explain the present invention, and similar parts have been designated with similar reference numerals throughout the specification.

[0047] [Secondary battery according to the first embodiment of the present invention]

[0048] FIG. 1 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention, and FIG. 2 is a partially enlarged cross-sectional view of FIG. 1.

[0049] The secondary battery (1) of the present invention includes an electrode assembly (11), a can (12) that accommodates the electrode assembly (11), and a cap assembly (13) mounted in an opening of the can (12), as illustrated in FIGS. 1 and 2.

[0050] electrode assembly

[0051] The electrode assembly (11) includes two electrodes having different polarities and having a wide plate shape in the form of a roll, and a separator interposed between the electrodes or placed below or above one of the electrodes to mutually insulate the electrodes, and the two electrodes and the separator have a structure in which they are wound in the form of a 'jelly roll'.

[0052] And the two electrodes each have a structure in which an active material slurry is applied to a current collector in the form of a metal foil or metal mesh containing aluminum and copper, respectively.

[0053] Here, the two electrodes can be anode and cathode.

[0054] Meanwhile, the positive electrode is provided with a positive tab, and the positive tab is connected to the cap assembly (13). The negative electrode is provided with a negative tab, and the negative tab is connected to the bottom surface of the can (12).

[0055] can

[0056] As illustrated in Fig. 1, the can (12) is made of a lightweight conductive metal material such as aluminum or an aluminum alloy, and has a cylindrical structure with an open top and a sealed bottom opposite thereto. An electrode assembly (11) and an electrolyte (not illustrated) are accommodated inside the can (12).

[0057] Meanwhile, the electrolyte is intended to move lithium ions generated by electrochemical reactions at the positive and negative electrodes during charging and discharging of a secondary battery. For example, the electrolyte may be a non-aqueous organic electrolyte, which is a mixture of a lithium salt and a high-purity organic solvent, or a polymer using a polymer electrolyte.

[0058] Cap assembly

[0059] The cap assembly (13) is mounted on the opening of the can (12), and includes a top cap (131) that supplies electricity to an external circuit, a safety element (132) (Positive Temperature Coefficient element) provided on the lower portion of the top cap (131), a safety vent (133) (Current Interrupt Device) provided on the lower portion of the safety element (132), a bottom cap (134) provided on the lower portion of the safety vent (133), a first insulator (135) provided between the safety vent (133) and the bottom cap (134), and a gasket (136) that surrounds the edges of the top cap (131), the safety element (132), and the safety vent (133) and is coupled to the opening of the can (12).

[0060] Meanwhile, when the secondary battery (1) is charged and discharged, the organic solvent is decomposed due to heat generation caused by an internal short circuit, generating high-temperature gas, and as a result, an explosion or rupture may occur due to an increase in gas pressure within the secondary battery (1).

[0061] In order to solve the above-mentioned problem, the secondary battery (1) of the present invention includes a top cap (131) that can quickly cut off the current when a high temperature occurs.

[0062] That is, the top cap (131) includes a deformable body (13132) that blocks electricity by being deformed when high heat is generated, and the safety of the secondary battery can be increased by the deformable body (13132).

[0063] FIG. 3 is a perspective view showing a top cap according to a first embodiment of the present invention, FIG. 4 is a cross-sectional view of FIG. 3, and FIG. 5 is a cross-sectional view showing a contracted state of a deformed body of a secondary battery according to the first embodiment of the present invention.

[0064] To explain in more detail, the top cap (131) includes a supply section (1311), a terminal section (1312), and an electrical cutoff section (1313), as illustrated in FIGS. 3 to 5.

[0065] The supply unit (1311) is made of a conductive metal material and has a structure that supplies electricity to an external circuit. For example, the supply unit (1311) has a metal plate shape. Meanwhile, the supply unit (1311) may be made of aluminum or an aluminum alloy.

[0066] The terminal section (1312) is for supplying electricity to the supply section (1311), and includes a terminal surface (13121) corresponding to the supply section (1311) and supplying electricity to the supply section (1311), and a coupling surface (13122) provided at the lower portion of the terminal surface (13121) and having a larger diameter than the terminal surface (13121) and having a gasket (136) coupled to the edge.

[0067] Here, the terminal portion (1312) may be made of the same material as the supply portion (1311). That is, the terminal portion (1312) may be aluminum or an aluminum alloy.

[0068] The above electric blocking unit (1313) has a structure that electrically connects the supply unit (1311) and the terminal unit (1312) or disconnects them so that electricity does not flow, depending on the deformation temperature.

[0069] That is, the electric blocking unit (1313) has a structure that electrically connects the supply unit (1311) and the terminal unit (1312) below the deformation temperature and separates the supply unit (1311) and the terminal unit (1312) above the deformation temperature so that electricity does not flow therebetween.

[0070] For example, the electrical circuit breaker (1313) includes an insulator (13131) and a transformer (13132).

[0071] An insulator (13131) is provided between the supply portion (1311) and the terminal portion (1312) to separate the supply portion (1311) and the terminal portion (1312) from each other so that they do not come into contact with each other. In particular, the insulator (13131) may be made of a non-conductive polyethylene (PE) material.

[0072] And both ends of the insulator (13131) can be bonded to the supply portion (1311) and the terminal portion (1312) by adhesive or heat fusion, respectively, thereby increasing the bonding between the supply portion (1311), the insulator (13131) and the terminal portion (1312).

[0073] In particular, the insulator (13131) may be formed of an insulating material with buffering capacity. In particular, the insulator (13131) may be formed of a material that compresses when a force exceeding a set value is applied, rather than a sponge-like material. Accordingly, the external shock transmitted from the supply unit (1311) can be buffered, thereby stably protecting the secondary battery from the external shock.

[0074] The deformed body (13132) electrically connects the supply part (1311) and the terminal part (1312) below the deformation temperature, and when deformed above the deformation temperature, the supply part (1311) and the terminal part (1312) are disconnected so that electricity does not flow.

[0075] That is, the deformable body (13132) has both ends connected to the supply portion (1311) and the terminal portion (1312), respectively, so that the supply portion (1311) and the terminal portion (1312) are electrically connected below the deformation temperature. Thereafter, when the secondary battery rises above the deformation temperature, it contracts and the connection with the supply portion (1311) or the terminal portion (1312) is cut off, resulting in the disconnection of the supply portion (1311) and the terminal portion (1312) so that electricity does not flow between them.

[0076] Here, the deformable body (13132) can be prepared as a shape memory alloy that contracts above the transformation temperature. A shape memory alloy is an alloy that remembers its original shape even when deformed by applying force and immediately returns to its original shape with a slight heating. In other words, the shape memory alloy was first discovered when the shape memory effect of a nickel-titanium alloy was discovered, and the shape memory effect is a phenomenon in which a shape memorized at a high temperature is remembered forever, and no matter how severe the deformation is at a low temperature, it immediately returns to its original shape with a slight heating.

[0077] For example, shape memory alloys include nickel-titanium alloys, copper-zinc alloys, gold-cadmium alloys, and iodium-thallium alloys.

[0078] In this way, when high heat higher than the deformation temperature is transmitted to the deformable body (13132) according to the first embodiment of the present invention, the deformable body (13132) contracts and the deformable body (13132) and the supply part (1311), or the deformable body (13132) and the terminal part (1312), or the deformable body (13132) are separated from both the supply part (1311) and the terminal part (1312), and as a result, electricity from the terminal part (1312) can be blocked from being supplied to the supply part (1311), and as a result, safety can be improved.

[0079] Meanwhile, the deformation temperature may be 70°C or higher. Preferably, the deformation temperature may be 120°C or higher. Here, if the deformation temperature is 70°C or lower, there is a problem that the deformation body (13132) may be deformed even from a heat source generated during normal operation of the secondary battery, and if it is 120°C or higher, the secondary battery may explode or rupture before the deformation body is deformed.

[0080] Meanwhile, the deformable body (13132) may have a shape that surrounds the exterior of the insulator (13131). Accordingly, the deformable body (13132) can be fixed to the insulator (13131) without a separate fixing means, thereby increasing the bonding strength and simplifying the structure.

[0081] For example, the insulator (13131) may have a cylindrical shape, and the deformable body (13132) may have a circular ring shape to surround the cylindrical insulator (13131). Of course, the insulator (13131) and the deformable body (13132) may also have shapes such as a square and a square ring, a triangle and a triangular ring, an oval and an elliptical ring.

[0082] Meanwhile, one end of the deformable body (13132) may be fixed to the supply unit (1311) or the terminal unit (1312). In particular, one end of the deformable body (13132) may be fixed to the supply unit (1311) or the terminal unit (1312) through an adhesive or heat fusion. Accordingly, the fixing force of the deformable body (13132) may be increased. For example, as seen in FIG. 3, the lower end of the deformable body (13132) may be fixed to the upper surface of the terminal unit (1312) through an adhesive or the like. Accordingly, when the deformable body (13132) contracts, the upper part of the deformable body (13132) contracts downward, and as a result, the supply unit (1311) and the deformable body (13132) are separated, thereby cutting off the power supply.

[0083] Meanwhile, the height of the electric blocking part (1313) may be formed to be 2 mm to 12 mm so as to minimize the gap between the supply part (1311) and the terminal part (1312). Here, if the height of the electric blocking part (1313) is 2 mm or less, even if the deformable body (13132) shrinks above the deformation temperature, the shrinkage amount of the deformable body (13132) is small, making it difficult to cut off electricity between the supply part (1311) and the terminal part (1312), and there is a problem that electricity may flow when the supply part (1311) and the deformable body (13132) or the terminal part (1312) and the deformable body (13132) separated by an external impact come into contact again. If the height of the electric cutoff section (1313) is 12 mm or more, electricity between the supply section (1311) and the terminal section (1312) can be quickly cut off above the deformation temperature, but there is a problem that the volume of the secondary battery increases as the height of the top cap (131) increases unnecessarily.

[0084] Meanwhile, the supply unit (1311) and the electric blocking unit (1313) may have the same diameter as the terminal surface (13121). Accordingly, it is possible to prevent a step from occurring between the supply unit (1311) and the electric blocking unit (1313) or the terminal surface (13121) and the electric blocking unit (1313).

[0085] In the secondary battery (1) according to the first embodiment of the present invention having such a structure, when the internal temperature is lower than the deformation temperature during charging and discharging, the deformable body (13132) does not contract, so that the electricity of the electrode assembly (11) is transmitted to the external circuit through the terminal portion (1312) of the top cap (131), the deformable body (13132), and the supply portion (1311). Here, when the temperature of the secondary battery rises above the deformation temperature due to overcharging, the deformable body (13132) contracts, and one end of the deformable body (13132) is separated from the supply portion (1311), and accordingly, the electricity of the electrode assembly (11) is transmitted to the terminal portion (1312) of the top cap (131) and the deformable body (13132), but is not transmitted to the supply portion (1311), so that electricity cannot be supplied to the external circuit, and as a result, the electricity may be quickly cut off.

[0086] Therefore, the secondary battery (1) according to the first embodiment of the present invention includes a top cap (131) having a supply portion (1311), a terminal portion (1312), and an electrical cutoff portion (1313), so that when a high temperature higher than the deformation temperature occurs, electricity can be quickly cut off, and thus safety can be greatly improved.

[0087] FIG. 6 is a cross-sectional view illustrating a safety vent of a secondary battery according to the first embodiment of the present invention, and FIG. 7 is a cross-sectional view illustrating a state in which the safety vent of a secondary battery according to the first embodiment of the present invention is contracted.

[0088] Meanwhile, the safety vent (133) includes a first deformable body (1331) that electrically contacts the bottom cap (134) below the deformation temperature and is deformed above the deformation temperature to be electrically insulated from the bottom cap (134).

[0089] That is, the first deformed body (1331) is deformed at a temperature higher than the deformation temperature in the same manner as the deformed body included in the top cap (131) and is separated from the bottom cap (134) so ​​that electricity does not flow therethrough, thereby enabling electricity to be quickly cut off.

[0090] Here, the first deformable body (1331) may be prepared from the same material as the deformable body described above. That is, the first deformable body (1331) may be prepared from a shape memory alloy that contracts above a deformation temperature.

[0091] Meanwhile, the deformation temperature at which the first deformation body (1331) is deformed is the same as the deformation temperature at which the deformation body described above is deformed.

[0092] Meanwhile, the first deformation body (1331) includes a contact portion (13311) that protrudes to contact the bottom cap (134) and a non-contact portion (13312) that does not contact the bottom can (12), and a second insulator (13313) may be provided between the non-contact portion and the bottom cap (134). That is, the second insulator (13313) may block the non-contact portion (13312) from electrically contacting the bottom cap (134).

[0093] Meanwhile, the safety vent (133) is provided on the upper surface of the first deformable body (1331) that does not face the bottom cap (134), and further includes a second deformable body (1332) having insulation.

[0094] That is, the second deformable body (1332) does not undergo deformation below the deformation temperature, but deforms above the deformation temperature, thereby separating the first deformable body (1331) and the bottom cap (134) from each other so that electricity does not flow, thereby enabling electricity to be quickly cut off.

[0095] That is, the safety vent (133) has a two-stage structure composed of a first deformable body (1331) and a second deformable body (1332), and accordingly, it can be quickly contracted above the deformation temperature, and as a result, contact with the bottom cap (134) can be quickly blocked.

[0096] Meanwhile, the second deformation body (1332) may be a shape memory polymer that shrinks above the deformation temperature.

[0097] Therefore, the secondary battery (1) according to the first embodiment of the present invention further includes a safety vent (133) composed of the first and second deformable bodies, thereby enabling the electricity to be quickly cut off when high heat exceeding the deformation temperature is generated, thereby enhancing safety.

[0098] Hereinafter, in describing other embodiments of the present invention, the same component symbols are used for components having the same functions as the above-described embodiments, and redundant descriptions are omitted.

[0099] [Secondary battery according to the second embodiment of the present invention]

[0100] FIG. 8 is a perspective view showing a top cap according to a second embodiment of the present invention, and FIG. 9 is a cross-sectional view showing a contracted state of a deformed body of a secondary battery according to the second embodiment of the present invention.

[0101] A secondary battery (1) according to a second embodiment of the present invention includes a top cap (131), as illustrated in FIGS. 8 and 9, and the top cap (131) includes a supply unit (1311) that supplies electricity to an external circuit, a terminal unit (1312) that supplies electricity to the supply unit (1311), and an electrical blocking unit (1313) that electrically connects the supply unit (1311) and the terminal unit (1312) or disconnects them from each other depending on a deformation temperature.

[0102] Here, the electric blocking unit (1313') includes an insulator (13131') provided between the supply unit (1311) and the terminal unit (1312) and separates the supply unit (1311) and the terminal unit (1312) from contact, and a deformation unit (13132') that electrically connects the supply unit (1311) and the terminal unit (1312) below a deformation temperature and disconnects the supply unit (1311) and the terminal unit (1312) from electrically conducting when changed above the deformation temperature.

[0103] Here, the deformation body (13132') is provided in a through hole that penetrates the upper surface of the insulator (13131') in the vertical direction, and has a structure in which both ends are in contact with the supply part (1311) and the terminal part (1312), respectively. Accordingly, there is no need to separately fix the deformation body (13132'), thereby simplifying the structure and increasing the efficiency of work.

[0104] Accordingly, when a high temperature higher than the deformation temperature occurs in the secondary battery (1) according to the second embodiment of the present invention, as shown in Fig. 9, the deformation body (13132') can contract to quickly cut off the electricity supply, thereby improving safety.

[0105] The scope of the present invention is indicated by the claims described below rather than the detailed description above, and various embodiments are possible derived from the meaning and scope of the claims and their equivalent concepts.

[0106]

[0107] [Explanation of symbols]

[0108] 1: Secondary battery

[0109] 11: Electrode assembly

[0110] 12: Can

[0111] 13: Cap assembly

[0112] 131: Top cap

[0113] 1311: Supply Department

[0114] 1312: Terminal section

[0115] 13121: Terminal surface

[0116] 13122: Mating surface

[0117] 1313: Electrical cutoff

[0118] 13131: Insulator

[0119] 13132: Variant

[0120] 132: Safety element

[0121] 133: Safety vent

[0122] 1331: First variant

[0123] 13311: Contact

[0124] 13312: Non-contact part

[0125] 13313: Second insulator

[0126] 1332: Second Variant

[0127] 134: Bottom Cap

[0128] 135: First insulator

[0129] 136: Gasket

Claims

1. A supply unit that supplies electricity to an external circuit; A terminal section for supplying electricity to the above supply section; It includes an electrical cutoff section that electrically connects the supply section and the terminal section or disconnects the supply section and the terminal section according to the deformation temperature, The above electric circuit breaker is, An insulator provided between the supply part and the terminal part and separating the supply part and the terminal part from contact; and A top cap including a deformable body that electrically connects the supply unit and the terminal unit below a deformation temperature and that deforms above the deformation temperature to disconnect the supply unit and the terminal unit from electrical conduction.

2. In claim 1, The above-mentioned deformation body is a top cap made of a shape memory alloy that shrinks above the deformation temperature.

3. In claim 1, The above deformation temperature is a top cap of 70℃ or higher.

4. In claim 1, The above-mentioned deformation body is a top cap having a shape that surrounds the outside of the insulator.

5. In claim 4, The above insulator has a cylindrical shape, The above-mentioned deformation body is a top cap having a circular ring shape surrounding the insulator.

6. In claim 1, The above insulator has a through hole formed that penetrates in the direction of the supply part and the terminal part, The above-mentioned deformation body is a top cap inserted into the through hole of the above-mentioned insulator, and both ends are in contact with the supply section and the terminal section, respectively.

7. In claim 1, One end of the above-mentioned deformation body is a top cap fixed to the supply portion or the terminal portion.

8. In claim 1, The height of the above electric cutoff part is formed as a top cap of 2mm to 12mm.

9. In claim 1, The above terminal part, A terminal surface that supplies electricity to the above supply section, It includes a mating surface provided at the lower portion of the terminal surface and having a diameter larger than the terminal surface, The above supply unit and the above electric cutoff unit have a top cap having the same diameter as the terminal surface.

10. A top cap for supplying electricity to an external circuit and provided according to claim 1; A safety element (Positive Temperature Coefficient element) provided at the bottom of the top cap; A safety vent (Current Interrupt Device) provided at the bottom of the above safety element; A bottom cap provided at the bottom of the above safety vent; A cap assembly including a first insulator provided between the safety vent and the bottom cap.

11. In claim 10, The above safety vent is, A cap assembly including a first deformable body that electrically contacts the bottom cap at a temperature below the deformation temperature and is deformed at a temperature above the deformation temperature to electrically separate from the bottom cap.

12. In claim 11, The above first deformation body is a cap assembly made of a shape memory alloy that contracts above a deformation temperature.

13. In claim 12, The first variant includes a contact portion that protrudes to contact the bottom cap and a non-contact portion that does not contact the bottom cap, A cap assembly having a second insulator between the non-contact portion and the bottom cap.

14. In claim 10, The above safety vent is, A cap assembly further comprising a second deformable body having insulating properties and provided on an upper surface of the first deformable body not facing the bottom cap.

15. In claim 14, The second deformation body is a cap assembly made of a shape memory polymer that does not undergo deformation below a deformation temperature and deforms above a deformation temperature.

16. A secondary battery comprising a cap assembly according to claim 10.

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