Cover plate, battery cell, battery pack, and electric device

Abstract

This application provides a cover plate, a battery cell, a battery pack, and an electrical device to address the problems of improving the stability of the opening pressure of an explosion-proof valve and improving the safety performance of the battery cell. The cover plate includes a substrate and an explosion-proof valve. The explosion-proof valve includes an opening portion, a notched portion, and a connecting portion. The welded portion of the connecting portion melts and solidifies with a portion of the substrate to form at least a part of a welded structure. The welded structure surrounds an explosion-proof hole on the substrate to seal the explosion-proof hole. The total volume of the welded structure is V1 mm. 3 Along the arrangement direction of the inner and outer circumferential surfaces of the connector, the distance between the welded part and the scored part is A mm; the total volume of the main body of the connector is V2 mm. 3 The total volume of the scored area is V3 mm. 3 A, V1, V2, and V3 satisfy the following: The cover plate provided in this application can reduce the impact of welding heat on the tensile strength of the scored portion of the explosion-proof valve during welding to the base plate, thereby improving the stability of the opening pressure of the explosion-proof valve.

Description

Technical Field

[0001] This application relates to the field of electrical equipment technology, specifically to a cover plate, a battery cell, a battery pack, and electrical equipment. Background Technology

[0002] A battery is a device that provides power to electrical equipment. A battery cell typically includes a casing, electrode assembly, cover plate, and explosion-proof valve. The electrode assembly is located inside the casing. The cover plate is used to seal the casing to protect the electrode assembly and other components, and to electrically connect the electrode assembly to external electrical components. The cover plate includes a base plate and an explosion-proof valve welded and fixed to the base plate.

[0003] In related technologies, during the production of the cover plate, the heat generated during the welding of the explosion-proof valve to the substrate will have a thermal effect on the grooved part of the explosion-proof valve, resulting in a decrease in the tensile strength of the grooved part, which in turn leads to a decrease in the stability of the opening pressure of the explosion-proof valve and affects the safety performance of the battery cell. Summary of the Invention

[0004] This application provides a cover plate, a battery cell, a battery pack, and an electrical device to address the issues of improving the stability of the opening pressure of an explosion-proof valve and enhancing the safety performance of the battery cell.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, embodiments of this application provide a cover plate, comprising: a substrate and an explosion-proof valve. The substrate has an explosion-proof hole. The explosion-proof valve is disposed at the explosion-proof hole; the explosion-proof valve includes: an opening portion, a notched portion, and a connecting portion. The notched portion is connected to the outer edge of the opening portion and surrounds the opening portion, and the thickness of the notched portion is less than the thickness of the opening portion. The connecting portion is connected to the outer edge of the notched portion and surrounds the notched portion; the connecting portion includes a main body portion and a welded portion, and the welded portion melts and solidifies with a portion of the substrate to form at least a portion of a welded structure; the welded structure surrounds the explosion-proof hole to seal the explosion-proof hole. The total volume of the welded structure is V1 mm. 3 Along the arrangement direction of the inner and outer circumferential surfaces of the connecting part, the distance between the welded structure and the scored part is A mm; the total volume of the main body is V2 mm. 3 The total volume of the scored area is V3 mm. 3 A, V1, V2, and V3 satisfy: .

[0007] In some possible implementations of the first aspect, A, V1, V2, and V3 also satisfy: .

[0008] In some possible implementations of the first aspect, the distance A between the welded structure and the notched portion also satisfies: 1mm≤A≤2mm.

[0009] In some possible implementations of the first aspect, the total volume V1 of the welded structure also satisfies: 10mm 3 ≤V1≤30 mm 3 .

[0010] In some possible implementations of the first aspect, the total volume V2 of the main body also satisfies: 25 mm 3 ≤V2≤60 mm 3 .

[0011] In some possible implementations of the first aspect, the total volume V3 of the notched portion also satisfies: 0.7 mm 3 ≤V3≤3 mm 3 .

[0012] In some possible implementations of the first aspect, along the arrangement direction of the inner and outer circumferential surfaces of the connection, the width L1 of the cross-section of the welded structure satisfies: 0.6mm≤L1≤1.2mm; the height L2 of the welded structure along the thickness direction of the explosion-proof valve satisfies: 0.25mm≤L2≤0.6mm.

[0013] In some possible implementations of the first aspect, the tensile strength σb of the notched portion satisfies: σb≥60MPa.

[0014] Secondly, embodiments of this application also provide a battery cell, comprising: a housing and a cover plate as described in any of the foregoing implementations. The housing has an opening. The cover plate is connected to the housing and seals the opening.

[0015] Thirdly, embodiments of this application also provide a battery pack, which includes the battery cells described in any of the foregoing implementations.

[0016] Fourthly, embodiments of this application also provide an electrical device, which includes an electrical main body and a battery pack as described in any of the foregoing implementations.

[0017] The cover plate, battery cell, battery pack, and electrical equipment provided in this application have the following beneficial effects:

[0018] The cover plate provided in this application has an explosion-proof hole on the substrate, and an explosion-proof valve is disposed at the explosion-proof hole. The explosion-proof valve includes an opening part, a serrated part connected to the outer edge of the opening part, and a connecting part connected to the outer edge of the serrated part. The welded part of the connecting part forms a welded structure around the explosion-proof hole with a part of the substrate, so that the explosion-proof valve can be connected to the substrate and seal the explosion-proof hole. By making the thickness of the serrated part less than the thickness of the opening part, when the battery cell using this cover plate experiences thermal runaway due to mechanical impact, internal abnormal connection short circuit, etc., the high temperature and high pressure gas inside the battery cell can cause the serrated part to break, so that the explosion-proof valve opens and is released from the explosion-proof hole to the outside of the battery cell, thereby ensuring the safety performance of the battery cell.

[0019] Based on this, by making This can reduce the impact of heat generated during welding of the explosion-proof valve to the substrate on the tensile strength of the scored part of the explosion-proof valve, while ensuring the connection strength between the connection part and the substrate. This is beneficial to improving the stability of the opening pressure of the explosion-proof valve and further improving the safety performance of the battery cell.

[0020] The beneficial technical effects of the battery cells, battery packs, and electrical equipment provided in this application are the same as those of the explosion-proof valve provided in this application, and will not be repeated here. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of an electrical device provided for some embodiments of this application.

[0022] Figure 2 for Figure 1 The diagram shows a cross-sectional view of the battery pack of the electrical device.

[0023] Figure 3 for Figure 2 The diagram shows the structural structure of the battery cells in the battery pack.

[0024] Figure 4 for Figure 3 A schematic diagram of part of the battery cell structure is shown.

[0025] Figure 5 for Figure 4 An exploded view of part of the battery cell structure shown.

[0026] Figure 6 for Figure 4 The diagram shows a cross-sectional view of a portion of the battery cell structure.

[0027] Figure 7 for Figure 6 A magnified view of a portion of point Q.

[0028] Figure 8 for Figure 7 A magnified view of the area at point K.

[0029] Figure 9 for Figure 4 The diagram shows the structure of the explosion-proof valve for the battery cell.

[0030] Figure 10 for Figure 9 The diagram shows a top view of the explosion-proof valve.

[0031] Figure 11 for Figure 10 The diagram shows a cross-sectional view of the explosion-proof valve at the BB line.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1000 electrical devices; 1100 main electrical components; 1200 battery compartments;

[0034] Battery pack 2000; casing 2001; battery cell 3000;

[0035] Explosion-proof valve 10; opening part 100; scoring part 200; scoring groove 210; opening section 211; connecting section 212; connecting part 300; main body part 310; welding part 320;

[0036] Cover plate 20; base plate 21; explosion-proof hole 21a; welding structure 22; pole post 30; pole group 40; housing 50; opening 51. Detailed Implementation

[0037] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0038] In this application, the accompanying drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features.

[0039] Unless otherwise stated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0040] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified. In the description of this application, "several" means one or more, unless otherwise explicitly specified.

[0041] In the description of this application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "height", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this application and do not indicate that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. In other words, they should not be construed as limitations on this application.

[0042] In the description of this application, unless otherwise expressly defined, the terms "installation," "connection," "linking," "fixing," "setting," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0043] In the description of this application, unless otherwise expressly defined, the terms "above," "over," "on top of," "below," "below," "under," or "below" for "first feature over second feature" can refer to the first and second features being in direct contact, or to the first and second features being in indirect contact through an intermediate medium. Furthermore, "above," "below," and "over" for "first feature over second feature" can mean the first feature is directly above or diagonally above the second feature, or simply indicates that the horizontal height of the first feature is higher than the horizontal height of the second feature. Similarly, "below," "below," and "below" for "first feature over second feature" can mean the first feature is directly below or diagonally below the second feature, or simply indicates that the horizontal height of the first feature is lower than the horizontal height of the second feature.

[0044] A battery is a device that provides power to electrical equipment. A battery cell typically includes a casing, electrode assembly, cover plate, and explosion-proof valve. The electrode assembly is located inside the casing, and the cover plate seals the casing and provides electrical connection between the electrode assembly and external electrical components. The cover plate includes a base plate and an explosion-proof valve welded to and fixed to the base plate.

[0045] In related technologies, unreasonable design of explosion-proof valve dimensions during the production of cover plates can cause the heat generated during welding of the explosion-proof valve to the substrate to have a thermal effect on the grooved part of the explosion-proof valve, resulting in a decrease in the tensile strength of the grooved part, which in turn reduces the stability of the opening pressure of the explosion-proof valve and affects the safety performance of the battery cell.

[0046] To address the aforementioned issues, this application provides a cover plate. By optimizing the parameters of the welding structure between the explosion-proof valve and the substrate and adjusting the size of the explosion-proof valve, the welding heat can be reduced during welding of the explosion-proof valve and the cover plate, thereby reducing the impact of welding heat on the tensile strength of the grooved portion of the explosion-proof valve. This, in turn, helps to improve the stability of the opening pressure of the explosion-proof valve and enhance the safety performance of the battery cell.

[0047] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0048] Please see Figure 1 , Figure 1 This is a schematic diagram of an electrical device 1000 provided in some embodiments of this application. Figure 1 In the illustrated embodiment, an electric vehicle is used as an example of the electrical device 1000 for illustrative purposes, which should not be construed as a specific limitation of this application. In other embodiments, the electrical device may also be a mobile phone, a laptop computer, a mobile charging station, or other similar devices.

[0049] Please continue reading. Figure 1 The electrical device 1000 includes a power-consuming body 1100 and a battery pack 2000. The battery pack 2000 is fixed to the power-consuming body 1100 and electrically connected to the power-consuming components of the power-consuming body 1100 to supply power to the power-consuming components of the power-consuming body 1100. Specifically, the power-consuming body 1100 may have a battery compartment 1200, and the battery pack 2000 is fixed inside the battery compartment 1200.

[0050] Please see Figure 2 , Figure 2 for Figure 1The diagram shows a cross-sectional view of the battery pack 2000 of the electrical device 1000. The battery pack 2000 may include a housing 2001 and at least one battery cell 3000, wherein the battery cell 3000 is electrically connected to the aforementioned electrical main body 1100. The battery cell 3000 is fixed inside the housing 2001, which protects the battery cell 3000 from external forces causing vibration and impact that could damage it. The housing 2001 may be a metal housing or a plastic housing.

[0051] Cell 3000 is the most basic electrochemical unit, capable of storing and releasing electrical energy. Cell 3000 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application does not limit it to these types.

[0052] Figure 2 In the battery pack 2000 shown, there are multiple battery cells 3000. These multiple cells 3000 can be electrically connected in series, in parallel, or in a mixed configuration. A mixed configuration means that the multiple cells 3000 are connected in both series and parallel relationships, which can be specifically designed according to the power requirements of the electrical device 1000. In some other embodiments, the battery pack 2000 may contain only one battery cell 3000.

[0053] Please refer to the following: Figures 3-5 , Figure 3 for Figure 2 A schematic diagram of the structure of the battery cell 3000 in the battery pack 2000 shown; Figure 4 for Figure 3 The diagram shows a partial structure of the 3000 battery cell. Figure 5 for Figure 4 The exploded view shows a portion of the structure of the battery cell 3000. The battery cell 3000 includes a cover plate 20, electrode posts 30, electrode groups 40, and a housing 50.

[0054] The housing 50 has a receiving cavity (not shown) and an opening 51 communicating with the receiving cavity. The receiving cavity is used to receive the electrode assembly 40 and the electrolyte, and the opening 51 is used to place the electrode assembly 40 in the receiving cavity.

[0055] Figure 3 In the illustrated embodiment, the housing 50 can be a rigid component, and the housing 50 can be generally rectangular in shape so that the battery cell 3000 is also generally rectangular. The housing 50 can be a metal housing.

[0056] In some examples, the housing 50 can be an aluminum alloy housing to make it lighter, which is beneficial for the weight reduction of the battery cell 3000, and thus for the overall weight reduction of the electrical equipment 1000. In other examples, the housing 50 can also be a stainless steel housing to make it stronger, which in turn gives the battery cell 3000 better overall strength and stronger resistance to puncture and vibration damage. In still other embodiments, the housing 50 can also be a flexible component.

[0057] The electrode assembly 40 is disposed within a receiving cavity and immersed in an electrolyte. The electrode assembly 40 includes a positive electrode (not shown), a negative electrode (not shown), and a separator (not shown). The positive electrode can be formed from a positive current collector and a positive active material coated on the positive current collector. In some examples, the positive current collector can be aluminum foil, and the positive active material can be lithium cobalt oxide (LCO), ternary materials (NCM / NCA), lithium iron phosphate (LFP), etc. Based on this, the electrode assembly 40 also includes a positive electrode tab (not shown), which is connected to the positive electrode and electrically conductive. Specifically, the positive electrode tab can be fixed to the positive current collector by welding or integrally formed with the positive current collector.

[0058] The negative electrode sheet can be formed from a negative current collector and a negative active material coated on the negative current collector. In some examples, the negative current collector can be copper foil, and the negative active material can be graphite, silicon-carbon composite material, etc. Based on this, the electrode assembly 40 also includes a negative electrode tab (not shown in the figure), which is connected to the negative electrode sheet and is electrically conductive. The negative electrode tab and the positive electrode tab are used to electrically connect the electrode assembly 40 to the circuit. Specifically, the negative electrode tab can be fixed to the negative current collector by welding, or it can be integrally formed with the negative current collector.

[0059] A separator is placed between the positive and negative electrode plates to isolate them and prevent short circuits. The separator can be made of porous polyethylene (PE) or polypropylene (PP), etc.

[0060] Please continue reading. Figures 3-5 The cover plate 20 includes a base plate 21 and an explosion-proof valve 10.

[0061] The substrate 21 is connected to the housing 50 and seals the opening 51 to protect the electrode assembly 40 and prevent electrolyte leakage. Figures 3-5 In the illustrated embodiment, the substrate 21 is generally rectangular flat. In other embodiments, the substrate 21 may also be circular, triangular, or other shapes.

[0062] The electrode post 30 is disposed on the substrate 21. Specifically, the electrode post 30 can be inserted and fixed to the substrate 21. Figure 3In the illustrated embodiment, the housing 50 has two openings 51, located at opposite ends of the housing 50. There are two substrates 21 and two pole pieces 30, with one substrate 21 blocking one opening 51. The two pole pieces 30 are fixed to the two substrates 21 respectively. The aforementioned positive electrode tab is electrically connected to one pole piece 30, and the aforementioned negative electrode tab is electrically connected to the other pole piece 30. In other embodiments, there may be only one opening 51 and one substrate 21, with the two pole pieces 30 spaced apart on the substrate 21.

[0063] The substrate 21 can be a metal structural component, connected to the housing 50 by welding, bonding, or snap-fitting. In some examples, the substrate 21 can be an aluminum alloy structural component, which is beneficial for the weight reduction of the battery cell 3000 and the electrical device 1000. In other examples, the substrate 21 can be a stainless steel component to give the substrate 21 higher strength, thereby giving the battery cell 3000 higher strength.

[0064] The substrate 21 has an explosion-proof hole 21a that penetrates the substrate 21 along the thickness direction. Figure 4 and Figure 5 In the embodiment shown, the inner wall of the explosion-proof hole 21a may be a stepped surface; the size of the end of the explosion-proof hole 21a facing the inside of the housing 50 is larger than the size of the end of the explosion-proof hole 21a facing the outside of the housing 50.

[0065] Please refer to the following: Figures 6-9 , Figure 6 for Figure 4 A cross-sectional view of a portion of the structure of battery cell 3000 shown; Figure 7 for Figure 6 A magnified view of a portion of point Q; Figure 8 for Figure 7 A magnified view of a section at point K; Figure 9 for Figure 4 The diagram shows the structure of the explosion-proof valve 10 of the battery cell 3000. The explosion-proof valve 10 is adapted to the shape of the explosion-proof hole 21a, and is disposed at the explosion-proof hole 21a on the substrate 21 and seals the explosion-proof hole 21a. The explosion-proof valve 10 can be a metal structural component. For example, the explosion-proof valve 10 can be an aluminum alloy structural component (such as a manganese-aluminum alloy component), which is beneficial for the weight reduction of the battery cell 3000 and the electrical equipment 1000. Alternatively, the explosion-proof valve 10 can also be a stainless steel structural component to give the explosion-proof valve 10 higher strength, thereby giving the battery cell 3000 higher strength.

[0066] Please continue reading. Figures 6-9The explosion-proof valve 10 includes an opening portion 100, a scoring portion 200, and a connecting portion 300. The scoring portion 200 is connected to the outer edge of the opening portion 100 and surrounds the opening portion 100. The connecting portion 300 is connected to the outer edge of the scoring portion 200 and surrounds the scoring portion 200. That is, both the scoring portion 200 and the connecting portion 300 are annular. For example, the scoring portion 200 and the connecting portion 300 can be circular, elliptical, polygonal, etc. The shapes of the scoring portion 200 and the connecting portion 300 can be the same or different, and this application does not limit them in this regard.

[0067] Specifically, the connecting portion 300 may be integrally formed with the etched portion 200; or, the etched portion 200 may be integrally formed with the opening portion 100; or, the connecting portion 300, the etched portion 200, and the opening portion 100 may be integrally formed. Based on this, the thickness of the etched portion 200 is less than the thickness of the opening portion 100 and the connecting portion 300.

[0068] In some examples, a groove 210 can be machined on a surface of the explosion-proof valve 10 arranged along the thickness direction by means of stamping, cutting, chemical etching, etc., to form a grooved portion 200.

[0069] As a result, the overall strength of the explosion-proof valve 10 is relatively weak at the etched portion 200. When the battery cell 3000 experiences thermal runaway due to mechanical impact, internal abnormal connection short circuit, or other reasons, the high temperature and high pressure gas inside the battery cell 3000 can cause the etched portion 200 to break, allowing the explosion-proof valve 10 to open and be released to the outside of the battery cell 3000 through the explosion-proof hole 21a.

[0070] Please refer to the following: Figure 10 and Figure 11 , Figure 10 for Figure 9 The explosion-proof valve 10 shown is a top view. Figure 11 for Figure 10 The diagram shows a cross-sectional view of the explosion-proof valve 10 at the BB line. The groove 210 includes an opening section 211 and a connecting section 212 connected together, with the depth of the opening section 211 greater than the depth of the connecting section 212. Thus, when the explosion-proof valve 10 is opened by pressure from inside the battery cell 3000, it can be disconnected from the opening section 211. The opening part 100 is connected to the connecting part 300 via the connecting section 212, preventing the opening part 100 from completely detaching from the connecting part 300 and potentially damaging the user or other components.

[0071] Please refer to the following: Figure 4 , Figure 5 and Figure 7As one possible implementation, the explosion-proof valve 10 is fixedly connected to the substrate 21 by welding. Specifically, the connecting portion 300 includes a main body portion 310 and a welding portion 320. The welding portion 320 melts and solidifies with a portion of the substrate 21 to form at least a part of the welding structure 22. That is, when the connecting portion 300 is welded to the substrate 21, the molten and solidified part is the welding portion 320, and the unmelted part is the main body portion 310. The welding structure 22 surrounds the explosion-proof hole 21a to seal the explosion-proof hole 21a with the explosion-proof valve 10. Figure 4 and Figure 7 In the embodiment shown, the explosion-proof valve 10 is located inside the explosion-proof hole 21a, and the connecting part 300 overlaps the stepped surface of the explosion-proof hole 31a. The aforementioned base plate 21 refers to the edge portion of the explosion-proof hole 21a.

[0072] In some embodiments, the explosion-proof valve 10 can be fixed to the substrate 21 by laser welding. In this case, the welded portion 320 and a portion of the substrate 21 melt and solidify to form the entire welded structure 22. Specifically, the laser welding power is greater than or equal to 400W and less than or equal to 700W. For example, the laser welding power can be 400W, 500W, 600W, or 700W, etc. The welding speed is greater than or equal to 25m / s and less than or equal to 50m / s. For example, the welding speed can be 25m / s, 30m / s, 40m / s, or 50m / s, etc.

[0073] Along the arrangement direction of the inner and outer peripheral surfaces of the connecting part 300 (e.g.) Figure 7 and Figure 8 As shown in the MN direction, the width L1 of the cross-section of the welded structure 22 satisfies: 0.6mm≤L1≤1.2mm. For example, along the arrangement direction of the inner and outer peripheral surfaces of the connecting part 300, the width L1 of the cross-section of the welded structure 22 can be 0.6mm, 0.8mm, 1.0mm or 1.2mm, etc.

[0074] The height L2 of the welded structure 22 along the thickness direction of the explosion-proof valve 10 satisfies: 0.25mm≤L2≤0.6mm. For example, the height L2 of the welded structure 22 along the thickness direction of the explosion-proof valve 10 is 0.25mm, 0.35mm, 0.45mm, 0.55mm or 0.6mm, etc.

[0075] In this way, while ensuring the strength of the welded structure 22 to ensure the connection strength between the explosion-proof valve 10 and the substrate 21, the thermal impact of welding heat on the etched portion 200 can be minimized.

[0076] In some other embodiments, the connecting part 300 and the substrate 21 can also be welded together with welding material. In this case, the welding part 320 and a part of the substrate 21 melt and solidify to form a part of the welding structure 22, and the welding material melts and solidifies to form another part of the welding structure 22.

[0077] Based on the above, please continue to refer to... Figure 7 and Figure 8 The total volume of welded structure 22 is V1 mm. 3 Along the arrangement direction of the inner and outer peripheral surfaces of the connecting portion 300, the distance between the welded structure 22 and the opening portion 100 is A mm; the total volume of the main body portion 310 is V2 mm. 3 The total volume of the scored section 200 is V3 mm. 3 Among them, A, V1, V2, and V3 satisfy: . The specific values ​​can be found in Table 1.

[0078] Understandably, when If the overall volume of the welding structure 22 is too large, it will cause more heat to be generated when the connection part 300 is welded to the substrate 21, which will reduce the tensile strength of the grooved part 200, thereby reducing the stability of the opening pressure of the explosion-proof valve 10 and affecting the safety performance of the battery cell 3000.

[0079] Therefore, the relationship between A, V1, V2, and V3 is defined as follows: This can reduce the heat generated during the welding of the explosion-proof valve 10 and the substrate 21, thus reducing the impact on the tensile strength of the grooved portion 200 of the explosion-proof valve 10. This, in turn, helps to improve the stability of the opening pressure of the explosion-proof valve 10 and improve the safety performance of the battery cell 3000.

[0080] For example, the tensile strength σb of the notched portion 200 is ≥ 60 MPa. For instance, the tensile strength σb of the notched portion 200 can be 60 MPa, 80 MPa, 100 MPa, 120 MPa, etc. This results in a high strength for the notched portion 200, which improves the stability of the opening pressure of the explosion-proof valve 10 and enhances the safety performance of the battery cell 3000.

[0081] Based on the above, A, V1, V2, and V3 also satisfy: Understandably, when If the overall volume of the welding structure 22 is too small, it will reduce the connection strength between the connecting part 300 and the substrate 21.

[0082] Therefore, the relationship between A, V1, V2, and V3 is defined as follows: This can reduce the impact of heat generated during welding of the explosion-proof valve 10 and the substrate 21 on the tensile strength of the grooved portion 200 of the explosion-proof valve 10, while ensuring the connection strength between the connection portion 300 and the substrate 21. This will help improve the stability of the opening pressure of the explosion-proof valve 10 and improve the safety performance of the battery cell 3000.

[0083] In some examples, the distance A between the welded structure 22 and the notched portion 200 also satisfies: 1mm ≤ A ≤ 2mm. The specific value of the distance A between the welded portion 320 and the notched portion 200 can be found in Table 1.

[0084] This prevents the distance between the welded structure 22 and the etched portion 200 from being too close, which would make the etched portion 200 susceptible to the effects of welding heat and weaken its strength. It also prevents the distance between the welded structure 22 and the etched portion 200 from being too far, which would result in a smaller area of ​​the opening portion 100 and reduce the gas emission efficiency.

[0085] In some examples, the total volume V1 of the welded structure 22 satisfies: 10 mm 3 ≤V1≤30 mm 3 The specific value of the total volume V1 of the welded structure 22 can be found in Table 1.

[0086] This prevents the overall volume of the welding structure 22 from being too large, which would result in excessive heat being generated during the welding of the explosion-proof valve 10 and the substrate 21, thus weakening the strength of the grooved portion 200. It also prevents the overall volume of the welding structure 22 from being too small, which would result in a weak connection between the explosion-proof valve 10 and the substrate 21, thereby leading to lower reliability of the battery cell 3000.

[0087] In some examples, the total volume V2 of the main body 310 also satisfies: 25 mm 3 ≤V2≤60 mm 3 The specific value of the total volume V2 of the main body 310 can be found in Table 1.

[0088] This approach prevents the overall volume of the main body 310 from becoming too large, which would result in an excessively large distance A between the welding structure 22 and the notched portion 200, or an excessively large thickness of the main body 310. In such cases, the welding structure 22 of the same volume would struggle to guarantee the connection strength between the explosion-proof valve 10 and the substrate 21. Furthermore, if the thickness of the main body 310 is too large, it would occupy more internal volume in the battery cell 3000, leading to a reduction in the battery cell's capacity. Conversely, this approach also prevents the overall volume of the main body 310 from becoming too small, which would result in an excessively small distance A between the welding structure 22 and the notched portion 200, or an excessively small thickness of the main body 310. In such cases, the welding heat from the welding structure 22 of the same volume would significantly impact the strength of the notched portion 200. Additionally, if the thickness of the main body 310 is too small, the overall strength of the explosion-proof valve 10 would be weak, leading to lower reliability of the battery cell 3000.

[0089] In some examples, the total volume V3 of the notched portion 200 also satisfies: 0.7 mm 3 ≤V3≤3 mm 3 The specific value of the total volume V3 of the scored section 200 can be found in Table 1.

[0090] This prevents the overall volume of the etched portion 200 from being too large, making it difficult to open the explosion-proof valve 10. It also prevents the overall volume of the etched portion 200 from being too small, resulting in weak strength of the etched portion 200, which in turn leads to lower stability of the opening pressure of the explosion-proof valve 10 and affects the safety performance of the battery cell 3000.

[0091] In some examples, the thermal conductivity σ of the explosion-proof valve 10 satisfies: 205 W / m·k ≤ σ ≤ 234 W / m·k. For example, the thermal conductivity σ of the explosion-proof valve 10 can be 205 W / m·k, 215 W / m·k, 225 W / m·k, or 234 W / m·k, etc. Thus, the relatively low thermal conductivity of the explosion-proof valve 10 is beneficial for reducing the thermal impact of welding heat on the scored portion 200.

[0092] The coefficient of thermal expansion γ of the explosion-proof valve 10 satisfies: 21.8 μm / m·k ≤ γ ≤ 25 μm / m·k. For example, the coefficient of thermal expansion γ of the explosion-proof valve 10 can be 21.8 μm / m·k, 23 μm / m·k, 24 μm / m·k, or 25 μm / m·k, etc. It can be understood that if the coefficient of thermal expansion of the explosion-proof valve 10 is too large, the explosion-proof valve 10 will generate excessive expansion when welded to the substrate 21, which will lead to a decrease in the tensile strength of the grooved portion 200. Therefore, by setting the coefficient of thermal expansion of the explosion-proof valve 10 to be less than or equal to 25 μm / m·k, it is beneficial to reduce the expansion caused by heat when the explosion-proof valve 10 is welded to the substrate 21, thereby improving the tensile strength of the grooved portion 200 of the explosion-proof valve 10.

[0093] To verify the design effect, please refer to Table 1. Table 1 shows that in Examples 1-10 and Comparative Examples 1-3 of this application, explosion-proof valves 10 with different design parameters were welded to the substrate 21 to form cover plates 20. After 32 cover plates 20 were randomly selected from each group of cover plates 20 with the same design parameters, burst tests were conducted, and the opening pressure Cpk was tested (the design opening pressure Cpk > 1.33 is considered to meet the usage requirements). The results are shown in Table 1.

[0094] Table 1

[0095]

[0096] As shown in Table 1, in Examples 1-10, when 1≤A≤2mm and 10≤V1≤30mm are satisfied... 3 25≤V2≤60mm 3 0.7≤V3≤3 mm 3 And 1.0≤ When the value is ≤4.0, the heat generated during welding of the explosion-proof valve 10 and the substrate 21 can be reduced while ensuring the connection strength between the connection part 300 and the substrate 21. This reduces the impact of the heat generated during welding of the explosion-proof valve 10 and the substrate 21 on the tensile strength of the grooved part 200 of the explosion-proof valve 10, thereby improving the stability and consistency of the opening pressure of the explosion-proof valve 10 and enhancing the safety performance of the battery cell 3000.

[0097] Conversely, see Comparative Examples 1-3, when V1 is too large, or The value is too small, resulting in When V1 is too large, the heat impact of the welding between the connecting part 300 and the substrate 21 on the scored part 200 increases, resulting in poor consistency of the opening pressure of the explosion-proof valve 10, and at least some of the explosion-proof valves 10 will not meet the usage requirements. Conversely, when V1 is too small, or The value is too large, resulting in If the size is too small, the strength of the welded structure 22 may be insufficient, affecting the safety performance of the battery cell 3000.

[0098] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0099] It is understood that the various implementation methods described in this application can be implemented individually or in combination, and the embodiments of this application are not limited in this respect.

[0100] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the aforementioned method implementations, and will not be repeated here.

[0101] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A cover plate, characterized in that, include: A substrate having explosion-proof holes; An explosion-proof valve is disposed at the explosion-proof port; the explosion-proof valve includes: Opening section; A serrated portion is connected to the outer edge of the opening portion and surrounds the opening portion, and the thickness of the serrated portion is less than the thickness of the opening portion; A connecting portion is attached to the outer edge of the etched portion and surrounds the etched portion; the connecting portion includes a main body and a welding portion, the welding portion and a portion of the substrate are melted and solidified to form at least a portion of a welded structure; the welded structure surrounds the explosion-proof hole to allow the explosion-proof valve to seal the explosion-proof hole; The total volume of the welded structure is V1 mm. 3 Along the arrangement direction of the inner and outer circumferential surfaces of the connecting portion, the distance between the welded structure and the scored portion is A mm; the total volume of the main body is V² mm. 3 The total volume of the scored portion is V3 mm. 3 A, V1, V2, and V3 satisfy: .

2. The cover plate according to claim 1, characterized in that, Along the arrangement direction of the inner and outer circumferential surfaces of the connecting part, the distance A between the welded structure and the scored part also satisfies: 1mm≤A≤2mm.

3. The cover plate according to claim 1, characterized in that, The total volume V1 of the welded structure also satisfies: 10mm 3 ≤V1≤30 mm 3 .

4. The cover plate according to claim 1, characterized in that, The total volume V2 of the main body also satisfies: 25 mm 3 ≤V2≤60 mm 3 .

5. The cover plate according to claim 1, characterized in that, The total volume V3 of the scored portion also satisfies: 0.7 mm. 3 ≤V3≤3 mm 3 .

6. The cover plate according to claim 1, characterized in that, Along the arrangement direction of the inner and outer circumferential surfaces of the connecting part, the width L1 of the cross-section of the welded structure satisfies: 0.6mm≤L1≤1.2mm; the height L2 of the welded structure along the thickness direction of the explosion-proof valve satisfies: 0.25mm≤L2≤0.6mm.

7. The cover plate according to claim 1, characterized in that, The tensile strength σb of the notched portion satisfies: σb≥60MPa.

8. A battery cell, characterized in that, include: A housing having an opening; A cover plate, wherein the cover plate is any one of claims 1-7, the cover plate being connected to the housing and sealing the opening.

9. A battery pack, characterized in that, include: The battery cell is the battery cell according to claim 8.

10. An electrical appliance, characterized in that, include: Electricity-consuming entities; as well as A battery pack, wherein the battery pack is the battery pack according to claim 9.

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