Hot melting cutter and battery module

Abstract

The utility model relates to the technical field of hot melting cutters, in particular to a hot melting cutter and a battery module. The hot melting cutter comprises a heating body and fusible alloy. The heating body comprises a heating bonding pad, a first electrode and a second electrode; the first electrode is connected with the second electrode through fusible alloy; the fusible alloy is provided with a third contact part which is in contact with the heating bonding pad; and the sectional area of the third contact part along the direction parallel to the X plane is not completely equal to or not equal to the sectional area of the fusible alloy non-third contact part area along the direction parallel to the X plane. The X plane is defined as a plane formed by intersecting the length direction of the heating bonding pad and the thickness direction of the heating bonding pad. By means of the design, current carrying can be guaranteed, the fusing time of fusible alloy can be shortened, and the fusing effect is accelerated.

Description

Technical Field

[0001] The utility model relates to the technical field of hot melt cutters, and particularly relates to a hot melt cutter and a battery module. Background Art

[0002] The controlled hot melt cutter is a surface-mounted product, usually used for lithium-ion battery packs as secondary protection, enabling it to act in a timely manner when suffering from overcurrent and overcharge risks, effectively reducing the fire and explosion caused by faults such as overcharging, over-discharging, and short-circuiting of lithium-ion batteries, and controlling the damage of circuits and devices in a relatively small area. To meet the current-carrying requirements above 40A, the existing solutions increase the thickness of the fusible alloy to meet the performance requirements. However, when the controlled disconnection occurs, there are situations such as a long melting time of the fusible alloy, poor melting effect, and accumulation and adhesion of the molten fusible alloy, resulting in a decline or even failure of the product performance. Summary of the Utility Model

[0003] The utility model provides a hot melt cutter, which can solve at least one problem in the background art to improve the melting effect of the fusible alloy and enhance the product performance.

[0004] The utility model provides a hot melt cutter, which at least includes a heating element and a fusible alloy.

[0005] The heating element at least includes a heating pad located on the surface of the heating element and a first electrode and a second electrode located on opposite sides along the length direction of the heating pad; the fusible alloy is located on the heating element; the first electrode is connected to the second electrode through the fusible alloy; the fusible alloy has a third contact portion in contact with the heating pad; the cross-sectional area of the third contact portion along a plane parallel to the X plane is not completely equal or not equal to the cross-sectional area of the non-third contact portion region of the fusible alloy along a plane parallel to the X plane; the X plane is defined as the plane formed by the intersection of the length direction and the thickness direction of the heating pad.

[0006] In some embodiments, the fusible alloy further has a first contact portion in contact with the first electrode and a second contact portion in contact with the second electrode; the minimum cross-sectional area of the third contact portion along a plane parallel to the X plane is smaller than the minimum cross-sectional area of the first contact portion and / or the second contact portion along a plane parallel to the X plane; or, the minimum cross-sectional area of the third contact portion along a plane parallel to the X plane is larger than the minimum cross-sectional area of the first contact portion and / or the second contact portion along a plane parallel to the X plane.

[0007] In some embodiments, at least one through groove is provided in the fusible alloy.

[0008] In some embodiments, when looking down at the fusible alloy from above the hot melt cutter, the third contact portion forms notches recessed towards the inside of the fusible alloy at opposite ends along the length direction of the heating pad; the notches extend towards the first electrode and the second electrode directions from the third contact portion.

[0009] In some embodiments, when looking down at the fusible alloy from above the thermal fuse cutter, the first contact portion and / or the second contact portion are provided with notches.

[0010] In some embodiments, when looking down at the fusible alloy from above the thermal fuse cutter, the fusible alloy located between the first contact portion and the third contact portion and / or between the second contact portion and the third contact portion is provided with notches.

[0011] In some embodiments, the notch is rectangular, V-shaped, trapezoidal or arc-shaped.

[0012] In some embodiments, the cross-sectional area of the fusible alloy parallel to the X plane gradually increases from the first electrode and / or the second electrode towards the heating pad.

[0013] In some embodiments, the thermal fuse cutter may further include a housing and a fuse-aid agent. The fuse-aid agent is located above the third contact portion on the surface of the fusible alloy away from the heating element. A cavity is formed inside the housing to accommodate the fuse-aid agent and the fusible alloy between the housing and the heating element.

[0014] The present utility model also provides a battery module, which adopts the thermal fuse cutter described in any one of the above embodiments.

[0015] The thermal fuse cutter provided by the present utility model can, through the design of the fusible alloy, provide a shrinkage space for the fusible alloy after melting while ensuring current carrying, reduce the melting time of the fusible alloy, and accelerate the melting effect.

[0016] Other features and beneficial effects of the present utility model will be described in the subsequent specification, and part of them will become obvious from the specification or be understood by implementing the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a three-dimensional exploded schematic view of the thermal fuse cutter provided by an embodiment of the present utility model;

[0019] Figure 2 It is a top view structural schematic diagram of the connection between the heating element and the fusible alloy provided by an embodiment of the present utility model;

[0020] Figure 3Schematic cross-sectional structure diagram of a hot-melt cutter provided by an embodiment of the present utility model;

[0021] Figures 4 to 12 Schematic diagram of different deformation embodiments of a fusible alloy provided by the present utility model.

[0022] Reference numerals:

[0023] 10 - Heating element; 11 - Heating pad; 12 - First electrode; 13 - Second electrode; 20 - Fusible alloy; 20a - Third contact part; 20b - First contact part; 20c - Second contact part; 21 - Through groove; 22 - Notch; 30 - Fusing aid; 40 - Outer shell. Detailed implementation manners

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model; the technical features designed in different implementation manners of the present utility model described below can be combined with each other as long as they do not conflict with each other; all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts belong to the scope of protection of the present utility model.

[0025] In the description of the present utility model, it should be noted that all terms (including technical terms and scientific terms) used in the present utility model have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present utility model belongs, and should not be construed as a limitation to the present utility model; it should be further understood that the terms used in the present utility model should be understood as having meanings consistent with their meanings in the context of this specification and the relevant technical fields, and should not be understood in an idealized or overly formal sense, unless clearly defined as such in the present utility model.

[0026] Please refer to Figures 1 to 3 , the present utility model provides a hot-melt cutter, and the hot-melt cutter at least includes a heating element 10 and a fusible alloy 20. The fusible alloy 20 is located on the heating element 10. The heating element 10 at least includes a heating pad 11 located on the surface of the heating element 10 and a first electrode 12 and a second electrode 13 located on opposite sides along the length direction of the heating pad 11. Among them, the fusible alloy 20 is respectively connected to the first electrode 12, the second electrode 13 and the heating pad 11 to form a mutually conductive loop.

[0027] Specifically, please refer to Figure 1, the heating element 10 further includes a heating body and a resistor (not shown in the figure) inside. Preferably, the resistor in the heating element 10 is centrally arranged below the heating pad 11, so that the third contact portion 20a can quickly absorb heat and improve the melting speed of the fusible alloy. Among them, the heating body is made of an insulating material, such as ceramic material, and a resistor is provided inside the heating body. When overvoltage occurs, the heating element 10 generates heat to promote the melting of the fusible alloy 20 above the heating pad 11, playing a role in cutting off the conducting circuit. At the same time, when overcurrent occurs, the fusible alloy 20 itself generates heat and melts to cut off the conducting circuit. The ends of the first electrode 12 and the second electrode 13 are mounted on the surface of the heating element 10. Among them, the first electrode 12 and the second electrode 13 are respectively provided with metal coatings, and the material of the metal coatings can be tin, silver, gold, etc. Through the mutual arrangement of the heating body, resistor, first electrode 12, second electrode 13, and fusible alloy 20 as described above, not only is the heat transfer path short, the heat transfer faster and more effective, but also after cutting off the current path at high temperature, it can avoid the first electrode 12, the second electrode 13, and the resistor attached to the surface of the heating element 10 from being re-breakdown, thereby improving the efficiency of heat transfer.

[0028] The fusible alloy 20 is preferably a low-melting-point fusible alloy. Refer to Figure 2 , the fusible alloy 20 has a third contact portion 20a in contact with the heating pad 11. Among them, the cross-sectional area of the third contact portion 20a along the plane parallel to the X plane is not completely equal or not equal to the cross-sectional area of the non-third contact portion region of the fusible alloy 20 along the plane parallel to the X plane. The X plane is defined as the plane formed by the intersection of the length direction of the heating pad 11 and the thickness direction of the heating pad 11.

[0029] It should be noted that the heating pad 11 can be arranged parallel or inclined at a certain angle along its length direction within the width range between the first electrode 12 and the second electrode 13. Among them, the length direction of the heating pad 11 is not consistent with the current flow direction between the first electrode 12 and the second electrode 13. In this embodiment, it is preferably that the length direction of the heating pad 11 is perpendicular to the current flow direction between the first electrode 12 and the second electrode 13. For example Figure 2 the X direction shown in is the length direction of the heating pad 11, and the Y direction shown is the current flow direction between the first electrode 12 and the second electrode 13. It should also be noted that the thickness direction of the heating pad 11 refers to the direction perpendicular to the surface of the heating pad 11. For example Figure 3The Z direction in [description] indicates the thickness direction of the heating pad 11. Therefore, the "X plane" here is defined as the plane formed by the intersection of the length direction (X direction) and the thickness direction (Z direction) of the heating pad 11. Further, a series of cross-sections can be cut along the third contact portion 20a parallel to the X plane. The "cross-sectional area of the third contact portion 20a parallel to the X plane" here refers to the area of all cross-sections formed parallel to the X plane in the third contact portion 20a. The "cross-sectional area of the non-third contact portion region of the fusible alloy 20 parallel to the X plane" here refers to the area of all cross-sections formed parallel to the X plane in the non-third contact portion region of the fusible alloy 20.

[0030] Specifically, the fusible alloy 20 includes a third contact portion 20a and a non-third contact portion region. In this embodiment, the cross-sectional areas of the third contact portion 20a and the non-third contact portion region parallel to the X plane can be made not completely equal or unequal by means such as opening through holes, cutting part of the alloy, or reducing the thickness at the third contact portion 20a or the non-third contact portion region of the fusible alloy 20. Through the above settings, when the fusible alloy 20 melts, due to the different cross-sectional areas in the fusible alloy 20, the part with a smaller cross-sectional area can act as the blasting opening for melting and melt first in advance, thereby attracting the molten alloy to contract towards the third contact portion 20a, the first electrode 12, and the second electrode 13. While maintaining a certain current-carrying capacity, the melting time is effectively shortened, and the melting speed and melting effect are improved. For example Figures 4 to 12 The positions indicated by the gray arrows in [description] are the possible blasting openings for preferential melting.

[0031] In a preferred embodiment, the fusible alloy 20 further has a first contact portion 20b in contact with the first electrode 12 and a second contact portion 20c in contact with the second electrode 13. The minimum cross-sectional area of the third contact portion 20a parallel to the X plane is smaller than the minimum cross-sectional area of the first contact portion 20b and / or the second contact portion 20c parallel to the X plane; or, the minimum cross-sectional area of the third contact portion 20a parallel to the X plane is larger than the minimum cross-sectional area of the first contact portion 20b and / or the second contact portion 20c parallel to the X plane.

[0032] It should also be noted that, similarly, a series of cross-sections can be formed by cutting the third contact portion 20a along a plane parallel to the X plane. The "minimum cross-sectional area of the third contact portion 20a along a plane parallel to the X plane" refers to the smallest cross-sectional area among all the cross-sections formed by the third contact portion 20a parallel to the X plane. Among them, the "minimum cross-sectional area of the first contact portion 20b and / or the second contact portion 20c along a plane parallel to the X plane" refers to the smallest cross-sectional area among all the cross-sections formed by the first contact portion 20b and the second contact portion 20c parallel to the X plane, or the smallest cross-sectional area among all the cross-sections formed by the first contact portion 20b parallel to the X plane, or the smallest cross-sectional area among all the cross-sections formed by the second contact portion 20c parallel to the X plane.

[0033] During specific implementation, the minimum cross-sectional area of the third contact portion 20a along the length direction of the heating pad 11 can be made smaller than the minimum cross-sectional area of the first contact portion 20b and / or the second contact portion 20c along the length direction of the heating pad 11 by means of opening a through-hole in the third contact portion 20a of the fusible alloy 20, or cutting a part of the alloy, or reducing the thickness, etc. For example Figures 4 to 10 In the different deformation embodiments of the fusible alloy 20 shown, a through-groove 21 is opened, or a part of the alloy is cut, or both are combined.

[0034] Similarly, the minimum cross-sectional area of the third contact portion 20a along the length direction of the heating pad 11 can be made larger than the minimum cross-sectional area of the first contact portion 20b or the second contact portion 20c along the length direction of the heating pad 11 by means of opening a through-groove 21 in the first contact portion 20b and / or the second contact portion 20c of the fusible alloy 20, or cutting a part of the alloy, or reducing the thickness, etc. For example Figure 11 、 Figure 12 In the different deformation embodiments of the fusible alloy 20 shown, a part of the alloy is cut.

[0035] By setting the cross-sectional area relationship of the first contact portion 20b, the second contact portion 20c, and the third contact portion 20a as described above, the structure of the fusible alloy 20 can be effectively adjusted. Further, when the fusible alloy 20 melts, due to the different cross-sectional areas in the fusible alloy 20, the part with a smaller cross-sectional area can act as a blasting opening for melting and fuse in advance, thereby attracting the molten alloy to contract towards the middle, effectively shortening the melting time while maintaining a certain current-carrying capacity, and improving the melting speed and melting effect.

[0036] Preferably, at least one through-groove 21 is opened in the fusible alloy 20, such as Figures 4 to 7Specifically, in order to ensure the uniformity of the fusible alloy 20 during the melting process, the shape of the through slot 21 in a top view projection is preferably an axisymmetric shape. As an example, the shape of the through slot 21 in a top view projection can be circular, rectangular, racetrack-shaped or other regular shapes. For example Figure 4 The through groove 21 in the embodiment is circular. Figure 5 The through groove 21 in the embodiment is in the shape of a racetrack. Specifically, the number of through grooves 21 and the spacing between each through groove 21 can be reasonably designed according to the size of the actual fusible alloy 20, and are not limited here. By providing the through grooves 21 on the fusible alloy 20 as described above, the through grooves 21 on the third contact portion 20a act as a bursting hole for melting first. In addition, since the cross-sectional areas of the first contact portion 20b and the second contact portion 20c are larger than the third contact portion 20a, the present embodiment preferably provides a through groove 21 on the third contact portion 20a, so that the alloy that is melted first on the third contact portion 20a shrinks toward the first contact portion 20b and the second contact portion 20c respectively due to the traction force, thereby achieving a rapid melting effect.

[0037] In some embodiments, when looking down from the top of the thermal fuse cutoff toward the fusible alloy 20, the third contact portion 20a forms notches 22 recessed toward the inside of the fusible alloy 20 at opposite ends along the length direction of the heating pad 11. In another alternative embodiment, when looking down from the top of the thermal fuse cutoff toward the fusible alloy 20, notches 22 recessed toward the inside of the fusible alloy 20 are formed at opposite ends along the length direction of the heating pad 11.

[0038] Specifically, the notch 22 may be formed only at two opposite ends of the third contact portion 20a, for example Figure 10 As shown. Preferably, the notch 22 is arranged to extend from the third contact portion 20a toward the first electrode 12 and the second electrode 13, wherein the notch 22 can extend to the first contact portion 20b and the second contact portion 20c, and can also provide traction while ensuring that the first contact portion 20b and the second contact portion 20c have a certain coverage area. Of course, the notch 22 may not extend to the first contact portion 20b and the second contact portion 20c. For example Figure 7 , Figure 9 In the embodiment, the notch 22 does not extend to the first contact portion 20b and the second contact portion 20c, thereby ensuring that the first contact portion 20b and the second contact portion 20c have sufficient traction to quickly attract the molten fusible alloy 20 toward the first electrode 12 and the second electrode 13, thereby improving the fusing efficiency.

[0039] The notches 22 may also be formed at opposite ends of the entire fusible alloy 20, for example Figures 4 to 9As shown. When the notch 22 is formed on the entire fusible alloy 20, the notch 22 can be formed at the first contact portion 20b and / or the second contact portion 20a and can extend toward the third contact portion 20a to the third contact portion 20a or not extend to the third contact portion 20a. For example Figure 11 it does not extend to the third contact portion 20a. In addition, the notch 22 can also be formed between the first contact portion 20b and the third contact portion 20a and / or between the second contact portion 20c and the third contact portion 20a. Similarly, it can extend toward the third contact portion 20a to the third contact portion 20a or not extend to the third contact portion 20a, and can also extend toward the first contact portion 20b or the second contact portion 20c to the first contact portion 20b or the second contact portion 20c, or not extend to the first contact portion 20b or the second contact portion 20c. Specific reasonable designs are made according to actual requirements and will not be overly limited here.

[0040] Among them, in order to ensure the uniformity of melting of the fusible alloy 20, the notch 22 is preferably designed in an axisymmetric shape. As an example, the notch 22 is rectangular or V-shaped or trapezoidal or arc-shaped or any combination of lines and planes. For example Figure 4 , Figure 5 , Figure 8 in which the notch 22 has an inwardly concave V-shaped structure, Figure 6 in which the notch 22 has an inwardly concave arc-shaped structure, Figure 7 in which the notch 22 has an inwardly concave rectangular structure, Figure 9 in which the notch 22 has an inwardly concave trapezoidal structure, Figure 10 in which the notch 22 has an inwardly concave U-shaped structure. Of course, according to this concept, the notch 22 can also be designed into other regular axisymmetric shapes, and the embodiments of the present disclosure are not limited thereto.

[0041] In some embodiments, looking down at the fusible alloy 20 from above the hot melt cutter, the cross-sectional area of the fusible alloy 20 parallel to the X plane gradually increases from the first electrode 12 and / or the second electrode 13 toward the heating pad 11. Through the design of gradually increasing the cross-sectional area, a blasting opening that preferentially melts can be generated at the variable cross-section, enabling the variable cross-section to be quickly melted, which also serves the purpose of reducing the melting time of the fusible alloy 20 and accelerating the melting effect. As Figure 11 , Figure 12 shown, a part of the four corners of the fusible alloy is cut off, so that the cross-sectional area of the fusible alloy 20 parallel to the X plane gradually increases from the first electrode 12 and / or the second electrode 13 toward the heating pad 11.

[0042] In other alternative embodiments, such as Figure 1 or Figure 3As shown in the figure, the hot melt cutter may further include a housing 40 and a fluxing agent 30. The fluxing agent 30 is located above the third contact portion 20a on the surface of the fusible alloy 20 away from the heating element 10. By providing the fluxing agent 30, the oxide layer on the surface of the fusible alloy 20 can be activated at high temperature, and the tension for the contraction of the fusible alloy 20 can be provided. A cavity is formed inside the housing 40 to accommodate the fluxing agent 30 and the fusible alloy 20 between the housing 40 and the heating element 10. The housing 40 may include a housing body and a cover body, which are detachably and fixedly connected to fix the internal components of the hot melt cutter inside the housing 40. Preferably, a plurality of interfaces are provided on the surface of the housing 40 to facilitate the lead-out of circuits. After the housing 40 is assembled with the internal components of the hot melt cutter, the interfaces can be sealed with epoxy resin to protect the hot melt cutter.

[0043] It should be noted that based on the above concept, according to the different actual requirements of the hot melt cutter, those skilled in the art can also set other internal components on the hot melt cutter, all of which fall within the protection scope of the present utility model.

[0044] The present utility model also provides a battery module, which adopts the hot melt cutter described in any one of the above embodiments. When the hot melt cutter designed by this solution is applied to the battery module, when the battery module has an overcurrent, the current passing through the fusible alloy 20 will generate heat due to the internal resistance of the fusible alloy 20 and cause the fusible alloy 20 to melt, thereby passively cutting off the conduction loop; when the battery module has a risk of overcharging, the hot melt cutter is turned on, and heat is generated by the hot melt cutter. This heat can cause the fusible alloy 20 to quickly melt under the action of the fluxing agent 30, thereby cutting off the conduction loop between the first electrode 12, the second electrode 13 and the heating pad 11. Through the fusing action of the above hot melt cutter, the out-of-control part can be kicked out of the module, preventing the further expansion of the out-of-control range, and effectively reducing the situation of fire and explosion caused by faults such as overcharging, over-discharging or short-circuiting of the battery module, and controlling the damage of the circuit and components in a relatively small area.

[0045] In summary, the hot melt cutter and the battery module provided by the present utility model, through the structural design of the fusible alloy, ensure current carrying while providing a contraction space for the fusible alloy after melting, not only reducing the melting time of the fusible alloy and accelerating the melting effect, but also effectively improving the controlled ability of the hot melt cutter.

[0046] In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present utility model can be improved in only one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or the background art at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation to that claim.

[0047] Although terms such as heating element, heating pad, first electrode, second electrode, fusible alloy, third contact portion, first contact portion, second contact portion, through groove, notch, fuse-aid agent, outer shell, etc. are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only for more conveniently describing and explaining the essence of the present utility model; interpreting them as any additional limitation is contrary to the spirit of the present utility model; the terms "first", "second", etc. (if any) in the description, claims and above-mentioned drawings of the embodiments of the present utility model are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit them; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present utility model.

Claims

1. A thermal cutoff device, characterized in that: include: A heating element; the heating element at least comprises a heating pad located on the surface of the heating element and a first electrode and a second electrode located on opposite sides along the length direction of the heating pad; A fusible alloy is located on the heating element; the first electrode is connected to the second electrode through the fusible alloy; the fusible alloy has a third contact portion in contact with the heating pad; The cross-sectional area of ​​the third contact portion parallel to the X plane is not completely equal or unequal to the cross-sectional area of ​​the non-third contact portion region of the fusible alloy parallel to the X plane; the X plane is defined as the plane formed by the intersection of the length direction of the heating pad and the thickness direction of the heating pad.

2. The thermal cutoff according to claim 1, characterized in that: The fusible alloy further comprises a first contact portion in contact with the first electrode and a second contact portion in contact with the second electrode; The minimum cross-sectional area of ​​the third contact portion along the direction parallel to the X-plane is smaller than the minimum cross-sectional area of ​​the first contact portion and / or the second contact portion along the direction parallel to the X-plane; or, the minimum cross-sectional area of ​​the third contact portion along the direction parallel to the X-plane is larger than the minimum cross-sectional area of ​​the first contact portion and / or the second contact portion along the direction parallel to the X-plane.

3. The thermal cutoff according to claim 1, characterized in that: The fusible alloy is provided with at least one through groove.

4. The thermal cutoff according to claim 1, characterized in that: Looking down toward the fusible alloy from above the thermal fuse cutoff, the third contact portion forms notches recessed toward the inside of the fusible alloy at opposite ends along the length direction of the heating pad; the notches extend from the third contact portion toward the first electrode and the second electrode.

5. The thermal cutoff according to claim 2, characterized in that: Looking down toward the fusible alloy from above the thermal cutoff, the first contact portion and / or the second contact portion is provided with a notch.

6. The thermal cutoff according to claim 2, characterized in that: Looking down toward the fusible alloy from above the thermal cutoff, the fusible alloy located between the first contact portion and the third contact portion and / or between the second contact portion and the third contact portion is provided with a notch.

7. The thermal cutoff according to claim 4, 5 or 6, characterized in that: The notch is rectangular, V-shaped, trapezoidal or arc-shaped.

8. The thermal cutoff according to claim 1, characterized in that: The cross-sectional area of ​​the fusible alloy along the direction parallel to the X plane gradually increases from the first electrode and / or the second electrode toward the heating pad.

9. The thermal cutoff according to claim 1, characterized in that: It also includes a shell and a flux, wherein the flux is located above a third contact portion on a surface of the fusible alloy away from the heating element; a cavity is formed inside the shell to accommodate the flux and the fusible alloy between the shell and the heating element.

10. A battery module, characterized in that: A thermal cutoff as described in any one of claims 1 to 9 is used.

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