Secondary battery top cover and secondary battery

Abstract

The application discloses a secondary battery top cover, which comprises an explosion-proof valve and an external short circuit connecting device; the explosion-proof valve comprises an explosion-proof sheet and a first insulating sheet, the first insulating sheet comprises a main body part and a protruding part; the external short circuit connecting device comprises a conductive connecting sheet, a second insulating sheet, an elastic deformation part and a conductive boss; the second insulating sheet insulates and separates the conductive connecting sheet and the conductive boss, the elastic deformation part comprises a fixed part and a movable part, the fixed part is arranged on the connecting sheet, the movable part is arranged correspondingly with the conductive boss and is insulated and separated by the protruding part and elastically deformed in a direction away from the conductive boss. The application provides a secondary battery top cover, which can not only timely and effectively release the pressure in the battery, but also timely trigger the external short circuit of the battery, prevent the thermal runaway phenomenon of the battery in a high-temperature environment and improve the safety of the whole battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a secondary battery top cover and a secondary battery. Background Technology

[0002] Lithium-ion batteries are widely used in consumer electronics, new energy vehicles, and energy storage due to their high energy density and long cycle life. However, as the demands for energy density in practical applications continue to increase, more materials with high energy density but poor thermal stability are entering commercial battery systems, posing a significant challenge to the safety performance of lithium-ion batteries.

[0003] Generally, when batteries are improperly used, such as overcharging, short-circuiting, or being exposed to high temperatures, internal reactions can easily generate large amounts of gas and heat, potentially leading to internal short circuits and thermal runaway. To mitigate the hazards caused by high internal pressure, an explosion-proof valve is typically installed on the battery cover. This valve releases pressure when the internal pressure reaches a certain level. However, even after pressure release, the battery still retains a high level of energy. If the external high-temperature environment cannot be changed, the high-energy substances inside the battery may still react violently and explode, causing unpredictable damage.

[0004] Existing designs that rely on pressure-triggered external short circuits to reduce the probability of thermal runaway, such as CN207038570U, inevitably have an external short circuit trigger pressure lower than the explosion-proof valve's relief pressure. Due to the large amount of gas produced by electrolyte decomposition at high temperatures, a significant amount of gas can be generated even without an internal short circuit risk, causing the internal pressure to reach the set external short circuit trigger value. Furthermore, the electrical connection between the positive and negative electrodes after external short circuit triggering actually accelerates the internal temperature rise, increasing the risk. If the design could trigger the external short circuit during or after pressure relief, premature external short circuit triggering could be avoided, thereby reducing the potential hazards caused by internal short circuits in high-energy internal materials during continuous temperature increases. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention provides a secondary battery top cover that can not only timely and effectively leak the internal pressure of the battery, but also promptly trigger an external short circuit in the battery, preventing thermal runaway in high-temperature environments and improving the overall safety of the battery.

[0006] The technical effects to be achieved by this invention are accomplished through the following solutions:

[0007] The secondary battery top cover of this invention includes an explosion-proof valve and an external short-circuit connection device. The explosion-proof valve includes an explosion-proof sheet and a first insulating sheet. The first insulating sheet includes a main body and a protrusion. The main body is disposed on the explosion-proof sheet, and the protrusion protrudes from the explosion-proof sheet and extends towards the external short-circuit connection device. The external short-circuit connection device includes a conductive connecting sheet, a second insulating sheet, an elastic deformable member, and a conductive boss. The second insulating sheet separates and insulates the conductive connecting sheet and the conductive boss. The elastic deformable member includes a fixed part and a movable part. The fixed part is disposed on the connecting sheet, and the movable part is correspondingly disposed with the conductive boss and is insulated by the protrusion, elastically deforming away from the conductive boss.

[0008] The explosion-proof valve is used to release pressure inside the battery; the external short-circuit connection device is used to connect the positive and negative terminals of the battery cell after the explosion-proof valve is released and disconnected from the battery, so as to cause a short circuit in the battery and prevent the battery from continuing to work and causing thermal runaway.

[0009] Furthermore, it also includes a top cover plate, a first electrode post, and a second electrode post; the top cover plate has electrode post holes, an explosion-proof valve hole, and a liquid injection hole; the electrode post holes are located at both ends of the top cover plate, the explosion-proof valve hole is located in the middle of the top cover plate, and the liquid injection hole is located between the explosion-proof valve and the first electrode post or the second electrode post; the first electrode post is located on one of the electrode post holes and is electrically connected to the conductive connecting piece, and is separated and insulated from the top cover plate by a third insulating piece; the second electrode post is located on the other electrode post hole and is electrically connected to the conductive boss through the top cover plate.

[0010] The top cover is used for the installation and fixation of the terminals, explosion-proof valve, and external short-circuit connection device, and is also sealed on the battery casing for the overall installation and sealing of the battery; the first and second terminals are used for the conduction and connection between the internal battery cells and the external circuit; the terminal hole is used for the installation and fixation of the first and second terminals; the explosion-proof valve hole is used for the installation and fixation of the explosion-proof valve; and the electrolyte injection hole is used for injecting electrolyte into the battery casing.

[0011] The explosion-proof sheet and the main body are integrated. When the internal pressure of the battery rises and reaches the set pressure relief value, the top cover sheet detaches to allow the internal pressure to leak. The protrusion is connected to the main body. When the battery is working normally, the protrusion is located between the movable part and the conductive boss, isolating the movable part and the conductive boss to ensure normal battery operation. When the internal pressure of the battery rises and reaches the set pressure relief value, the explosion-proof sheet and the main body detach from the top cover sheet to relieve pressure. The protrusion detaches from the top cover sheet along with the explosion-proof sheet and the main body. The movable part elastically deforms towards the conductive boss, and the movable part and the conductive boss make contact and conduct electricity. This causes the first terminal electrically connected to the movable part and the second terminal electrically connected to the conductive boss to become connected and conductive, thereby connecting the positive and negative terminals of the battery cell, causing a short circuit in the battery, and preventing the battery from continuing to operate in a high-temperature environment and causing thermal runaway. When the internal gas pressure of the battery reaches the set pressure relief value, the internal state is unstable and an internal short circuit may occur at any time. At this time, triggering an external short circuit can reduce the possibility of an internal short circuit and connect the external short circuit when the internal temperature is released after pressure relief, so as to avoid excessive temperature rise.

[0012] To further optimize the structure, the explosion-proof valve and the external short-circuit connection device can be located on the top or bottom side of the top cover plate.

[0013] Furthermore, the external short-circuit connection device is located between the first or second pole and the explosion-proof valve.

[0014] To further optimize the structure, the conductive protrusion can be integrally formed with the top cover plate as a single component or set as an independent component on the top cover plate. The independent component is a metal part or a resistive element with resistance value, which facilitates the dissipation of electrical energy and heat generation, thereby achieving heat dissipation when triggered by an external short circuit.

[0015] Furthermore, a magnet is provided on the conductive protrusion. The magnetic attraction of the magnet to the elastic deformable member ensures that the movable part of the elastic deformable member is in close contact with the conductive protrusion, thus guaranteeing the tightness of the external short-circuit connection.

[0016] Furthermore, the size of the protrusion is larger than the contact size with the conductive boss, completely separating and insulating the movable part from the conductive boss, effectively preventing the movable part from accidentally contacting the conductive boss during normal battery operation and triggering the external short circuit device; the length of the protrusion is less than the length of the main body, which is 1 / 10 to 1 / 9 of the length of the main body, so that when the explosion-proof valve is ejected, the protrusion can be effectively pulled out from between the conductive boss and the movable part of the elastic deformation member.

[0017] Furthermore, the first insulating sheet is made of a high-temperature resistant flexible insulating material including polytetrafluoroethylene, polyimide, or polyamide; it not only has good corrosion resistance and insulation properties, but also good tensile strength.

[0018] Furthermore, the elastic deformable element is made of shape memory alloy, such as Au-Cd, Ag-Cd, Cu-Zn, Cu-Zn-Al, Cu-Zn-Sn, Cu-Zn-Si, Cu-Sn, Cu-Zn-Ga, In-Ti, Au-Cu-Zn, Ni-Al, Fe-Pt, Ti-Ni, Ti-Ni-Pd, Ti-Nb, U-Nb, or Fe-Mn-Si. Under the abutment of the protrusion, the elastic deformable element deforms, isolating itself from the conductive boss. When the protrusion is withdrawn, the movable part of the elastic deformable element quickly returns to its original shape, making close contact with the conductive boss, thereby establishing electrical conductivity and achieving an electrical connection.

[0019] A secondary battery includes a casing, a battery cell, and a secondary battery top cover as described above. The casing and the secondary battery top cover are used for the installation, fixing, and protection of the battery cell. The battery cell is disposed inside the casing, and the secondary battery top cover is sealed and installed on the casing. The bottom of the first terminal and the second terminal are electrically connected to the positive or negative electrode of the battery cell, respectively.

[0020] The secondary battery top cover of the present invention has the following advantages:

[0021] 1. Before the external short circuit is triggered, the external short circuit device is separated by insulating parts. Under the memory effect and superelasticity of the elastic deformation part, the movable part of the elastic deformation part and the conductive protrusion have a clamping force on the protrusion of the first insulating part. This can effectively prevent the external short circuit device from being accidentally triggered during the transportation, use or other reasons of the secondary battery, and greatly reduce the probability of the external short circuit device being accidentally triggered.

[0022] 2. The connecting element of the external short-circuit device is an elastic deformable part, which can quickly contact the conductive boss to conduct electricity after the first insulating sheet protrusion is pulled out, ensuring the stability and timeliness of the external short-circuit device triggering.

[0023] 3. The external short-circuit device is triggered by the explosion-proof valve. After the explosion-proof valve is ejected, the external short circuit is quickly triggered. The combination of the explosion-proof valve and the external short-circuit device effectively avoids the phenomenon that the secondary battery cannot terminate thermal runaway after depressurization in a high-temperature environment, and reduces the probability of thermal runaway of the secondary battery in a high-temperature environment.

[0024] 4. The secondary battery top cover of the present invention aims to maximize the battery's internal pressure bearing capacity, avoid premature external short circuits, solve the safety hazards caused by high-energy substances inside the secondary battery after effective pressure relief in high-temperature environments, and avoid the hazards of thermal runaway after pressure relief. Attached Figure Description

[0025] Figure 1 This is a schematic cross-sectional view of the top cover of the secondary battery in this invention.

[0026] Figure 2 This is a top view of the secondary battery top cover in this invention.

[0027] Figure 3 This is a cross-sectional schematic diagram of another structure of the secondary battery top cover in this invention.

[0028] The annotations in the attached figures are explained as follows:

[0029] 10. Top cover plate; 11. Pole post hole; 12. Explosion-proof valve hole; 13. Liquid injection hole; 14. Third insulating sheet; 20. First pole post; 30. Second pole post; 40. Explosion-proof valve; 41. First insulating sheet; 411. Main body; 412. Protrusion; 42. Explosion-proof sheet; 50. External short-circuit connection device; 51. Conductive connecting piece; 52. Second insulating sheet; 53. Elastic deformation member; 531. Fixed part; 532. Movable part; 54. Conductive boss. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] The secondary battery top cover in the embodiments of the present invention is shown in the attached figure. Figure 1-3 As shown, the device includes an explosion-proof valve 40 and an external short-circuit connection device 50. The explosion-proof valve includes an explosion-proof sheet 42 and a first insulating sheet 41. The first insulating sheet includes a main body 411 and a protrusion 412. The main body is disposed on the explosion-proof sheet, and the protrusion extends beyond the explosion-proof sheet towards the external short-circuit connection device. The external short-circuit connection device includes a conductive connecting piece 51, a second insulating sheet 52, an elastic deformable member 53, and a conductive boss 54. The second insulating sheet separates and insulates the conductive connecting piece and the conductive boss. The elastic deformable member includes a fixed part 531 and a movable part 532. The fixed part is disposed on the connecting piece, and the movable part is correspondingly disposed to the conductive boss and is insulated by the protrusion, elastically deforming away from the conductive boss.

[0032] It also includes a top cover plate 10, a first pole 20, and a second pole 30; the top cover plate has pole hole 11, explosion-proof valve hole 12, and liquid injection hole 13; the pole hole is located at both ends of the top cover plate, the explosion-proof valve hole is located in the middle of the top cover plate, and the liquid injection hole is located between the explosion-proof valve and the first pole or the second pole; the first pole is located on one of the pole holes and is electrically connected to the conductive connecting piece, and is separated and insulated from the top cover plate by the third insulating piece 14; the second pole is located on the other pole hole and is electrically connected to the conductive boss through the top cover plate.

[0033] The explosion-proof valve is used for internal pressure relief within the battery. The external short-circuit connection device connects the positive and negative terminals of the battery cell after the explosion-proof valve detaches from the battery, causing a short circuit and preventing thermal runaway. The top cover is used for the installation and fixation of the terminals, explosion-proof valve, and external short-circuit device, and is also sealed to the battery casing for overall battery installation and sealing. The first and second terminals are used for conductivity and connection between the internal battery cells and external circuits. The terminal hole is used for the installation and fixation of the first and second terminals. The explosion-proof valve hole is used for the installation and fixation of the explosion-proof valve. The electrolyte injection hole is used to inject electrolyte into the battery casing. The explosion-proof valve and external short-circuit connection device can be located on the top or bottom side of the top cover. The external short-circuit connection device is located between the first or second terminal and the explosion-proof valve.

[0034] The explosion-proof plate and the main body are integrated. When the internal pressure of the battery rises and reaches the set pressure relief value, the top cover plate detaches to release the internal pressure. The protrusion is connected to the main body. When the battery is working normally, the protrusion is located between the movable part and the conductive boss, isolating the movable part and the conductive boss to ensure normal battery operation. When the internal pressure of the battery rises and reaches the set pressure relief value, the explosion-proof plate and the main body detach from the top cover plate to release pressure. The protrusion detaches from the top cover plate along with the explosion-proof plate and the main body. The movable part elastically deforms towards the conductive boss, and the movable part and the conductive boss come into contact and conduct electricity. This causes the first terminal electrically connected to the movable part and the second terminal electrically connected to the conductive boss to become conductive, thereby connecting the positive and negative terminals of the battery cell, causing a short circuit in the battery, and preventing the battery from continuing to operate in a high-temperature environment and causing thermal runaway. When the internal gas pressure of the battery reaches the set pressure relief value, the internal state is unstable and an internal short circuit may occur at any time. At this time, triggering an external short circuit can reduce the possibility of an internal short circuit and connect the external short circuit when the internal temperature is released after pressure relief, so as to avoid excessive temperature rise.

[0035] The conductive boss 54 can be integrally formed with the top cover plate as a single component or set as an independent component on the top cover plate. The independent component is a metal part with resistance or a resistive element, facilitating the dissipation of electrical energy and heat generation, thereby achieving heat dissipation during external short-circuit triggering. A magnet is provided on the conductive boss; the magnetic attraction of the magnet to the elastic deformable component ensures tight contact between the movable part of the elastic deformable component and the conductive boss, guaranteeing a tight external short-circuit connection. The size of the protrusion is larger than the contact size with the conductive boss, completely isolating and insulating the movable part from the conductive boss, effectively preventing accidental contact between the movable part and the conductive boss during normal battery operation, thus triggering the external short-circuit device. The length of the protrusion is less than the length of the main body, ranging from 1 / 10 to 1 / 9 of the main body length, facilitating effective extraction of the protrusion from between the conductive boss and the movable part of the elastic deformable component when the explosion-proof valve is ejected.

[0036] The first insulating sheet 41 is made of a high-temperature resistant flexible insulating material including polytetrafluoroethylene, polyimide, or polyamide; it not only has good corrosion resistance and insulation properties, but also good tensile strength. The elastic deformation element is made of shape memory alloy, such as Au-Cd, Ag-Cd, Cu-Zn, Cu-Zn-Al, Cu-Zn-Sn, Cu-Zn-Si, Cu-Sn, Cu-Zn-Ga, In-Ti, Au-Cu-Zn, Ni-Al, Fe-Pt, Ti-Ni, Ti-Ni-Pd, Ti-Nb, U-Nb, or Fe-Mn-Si; the elastic deformation element deforms under the pushing action of the protrusion, isolating itself from the conductive boss; when the protrusion is pulled out, the movable part of the elastic deformation element quickly returns to its original shape before deformation, making close contact with the conductive boss, thereby connecting the conductor and achieving electrical connection.

[0037] A secondary battery includes a casing, a battery cell, and a secondary battery top cover. The casing and the secondary battery top cover are used for the installation, fixing, and protection of the battery cell. The battery cell is disposed inside the casing, and the secondary battery top cover is sealed and installed on the casing. The bottom of the first terminal and the second terminal are electrically connected to the positive or negative electrode of the battery cell, respectively.

[0038] In the embodiments of the present invention, the top cover of the secondary battery uses the ejection of the explosion-proof valve as the starting point for triggering a battery short circuit. After the explosion-proof valve is ejected, the elastic deformation member of the external short circuit device can quickly contact the conductive boss to conduct electricity after the protrusion of the first insulating sheet is pulled out, triggering an external short circuit in the battery. This not only ensures the stability and timeliness of the triggering of the external short circuit device, but also effectively avoids the phenomenon that the secondary battery cannot terminate thermal runaway after depressurization in a high-temperature environment through the combination of the explosion-proof valve and the external short circuit device, reducing the probability of thermal runaway of the secondary battery in a high-temperature environment.

[0039] In addition, before the external short circuit is triggered, the external short circuit device is separated by an insulating component. Furthermore, the movable part of the elastic deformable component and the conductive protrusion have a clamping force on the protrusion of the first insulating component under the memory effect and superelasticity of the elastic deformable component. This can effectively prevent the external short circuit device from being accidentally triggered during transportation, use, or other reasons, and greatly reduce the probability of the external short circuit device being accidentally triggered.

[0040] As can be seen from the above embodiments, the present invention provides a secondary battery top cover that can not only timely and effectively leak the internal pressure of the battery, but also timely trigger the battery to have an external short circuit, preventing the battery from experiencing thermal runaway under high temperature conditions, and improving the overall safety of the battery.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and not to limit them. Although the embodiments of the present invention have been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the embodiments of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A secondary battery top cover characterized by comprising: The explosion-proof valve and the external short-circuit connecting device are provided. The explosion-proof valve comprises an explosion-proof sheet and a first insulating sheet, and the first insulating sheet comprises a main body part and a protruding part. The external short-circuit connecting device comprises a conductive connecting sheet, a second insulating sheet, an elastic deforming part and a conductive boss; the second insulating sheet insulates the conductive connecting sheet and the conductive boss; the elastic deforming part comprises a fixed part and a movable part; the fixed part is arranged on the conductive connecting sheet; the movable part is arranged corresponding to the conductive boss and is insulated by the protruding part and elastically deformed away from the conductive boss. The explosion-proof sheet and the main body part are integrated; and the protruding part is connected with the main body part.

2. The top cover of the secondary battery according to claim 1, wherein: The top cover sheet, the first pole and the second pole are further provided; the top cover sheet is provided with pole holes, explosion-proof valve holes and liquid injection holes; the pole holes are arranged at the two ends of the top cover sheet, the explosion-proof valve holes are arranged at the middle of the top cover sheet, and the liquid injection holes are arranged between the explosion-proof valve and the first pole or the second pole; The first pole is arranged on one of the pole holes, is electrically connected with the conductive connecting sheet and is insulated from the top cover sheet by a third insulating sheet; and the second pole is arranged on the other pole hole and is electrically connected with the conductive boss through the top cover sheet.

3. The top cover of the secondary battery according to claim 2, wherein: The explosion-proof valve and the external short-circuit connecting device can be arranged on the top side or the bottom side of the top cover sheet.

4. The top cover of the secondary battery according to claim 2, wherein: The external short-circuit connecting device is arranged between the first pole or the second pole and the explosion-proof valve.

5. The top cover of the secondary battery according to claim 2, wherein: The conductive boss can be integrally formed with the top cover sheet as one element or arranged on the top cover sheet as an independent element; the independent element is a metal element with a resistance value or a resistance element.

6. The top cover of the secondary battery according to claim 1, wherein: A magnet is arranged on the conductive boss.

7. The top cover of the secondary battery according to claim 1, wherein: The size of the protruding part is greater than the contact size of the conductive boss, and the length of the protruding part is less than the length of the main body part, which is 1 / 10-1 / 9 of the length of the main body part.

8. The top cover of the secondary battery according to claim 1, wherein: The first insulating sheet is made of a high-temperature-resistant flexible insulating material, such as polytetrafluoroethylene, polyimide or polyamide.

9. The top cover of the secondary battery according to claim 1, wherein: The elastic deforming part is made of a shape memory alloy material; the shape memory alloy material is Au-Cd, Ag-Cd, Cu-Zn, Cu-Zn-Al, Cu-Zn-Sn, Cu-Zn-Si, Cu-Sn, Cu-Zn-Ga, In-Ti, Au-Cu-Zn, Ni-Al, Fe-Pt, Ti-Ni, Ti-Ni-Pd, Ti-Nb, U-Nb or Fe-Mn-Si.

10. A secondary battery characterized by comprising: The secondary battery top cover comprises a shell, an electric core and the secondary battery top cover of any one of claims 1-9; the electric core is arranged inside the shell, the secondary battery top cover is sealingly arranged on the shell, and the bottom of the first pole and the second pole is respectively electrically connected with the positive sheet or the negative sheet of the electric core.

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