Safety structure and electrochemical device

Abstract

The utility model discloses a safety structure and an electrochemical device. The safety structure comprises a first conductive piece, a second conductive piece, an insulating layer, a thermal shrinkable sleeve and a current limiting assembly, the first conductive part, the insulating layer and the second conductive part are sequentially stacked, the melting point of the insulating layer is not higher than that of the first conductive part and the second conductive part, and the first conductive part and the second conductive part are coated with the thermal shrinkable sleeve; one end of the first conductive member away from the insulating layer is electrically connected with the current-limiting assembly; the surface, facing the second conductive piece, of the first conductive piece is provided with a first protrusion, and / or the surface, facing the first conductive piece, of the second conductive piece is provided with a second protrusion.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a safety structure and an electrochemical device. Background Art

[0002] As a secondary battery, lithium-ion batteries have been widely used in mobile phones, laptops, electric vehicles, etc. due to their high energy density and good charge and discharge cycle capacity. With the gradual increase in battery energy density and charge and discharge rate, higher requirements are placed on the safe use of lithium-ion batteries.

[0003] Generally speaking, when the internal temperature of the battery is around 100°C, the solid electrolyte interface (SEI) film on the electrode surface begins to decompose rapidly, and the triggering conditions for battery thermal runaway begin to be established. Afterwards, as a series of chain exothermic reactions occur, the heating rate inside the battery increases exponentially, and the temperature quickly approaches the ignition point of the flammable electrolyte, causing the battery to burn and explode. Therefore, lithium-ion batteries are prone to thermal runaway when they are abused by high-temperature baking.

[0004] To solve the above problems, the usual approach is to use more stable positive electrode materials, negative electrode materials and electrolytes in lithium-ion batteries. This approach can improve the safety of the battery to a certain extent, as it can pass the oven baking test at a higher temperature. However, there is a problem with this solution. Usually, more stable positive electrode materials, negative electrode materials and electrolytes will lead to side effects such as increased internal resistance and decreased capacity, which ultimately leads to higher impedance of lithium-ion batteries, decreased rate charge and discharge performance, and decreased energy density.

[0005] Therefore, how to develop a new safety structure that can effectively improve the furnace temperature safety performance of lithium-ion batteries and avoid side effects such as increased battery internal resistance and decreased capacity is a technical problem that needs to be urgently solved by technical personnel in this field.

[0006] Most of the metal sheets in the existing safety structure adopt a planar design, which cannot completely eliminate polymers at high temperatures, resulting in insufficient electrical contact and excessive resistance, which in turn causes less discharge when connected to the positive and negative poles of the battery. In addition, due to the slow elimination of polymers by the planar metal sheets, the electrical connection cannot be triggered in time. Utility Model Content

[0007] The main purpose of the present application is to provide a safety structure and an electrochemical device to solve the problem that the metal sheet in the existing safety structure adopts a planar design, the polymer is slowly eliminated or cannot be completely eliminated, resulting in the failure to trigger the electrical connection in time or the electrical contact is insufficient, resulting in excessive resistance.

[0008] According to one aspect of the present application, a safety structure is provided, including: a first conductive member, a second conductive member, an insulating layer, a heat shrink sleeve and a current limiting component; the first conductive member, the insulating layer and the second conductive member are stacked in sequence, the melting point of the insulating layer is not higher than that of the first conductive member and the second conductive member, and the heat shrink sleeve is covered on the outside of the first conductive member and the second conductive member; one end of the first conductive member away from the insulating layer is electrically connected to the current limiting component; a first protrusion is provided on the surface of the first conductive member facing the second conductive member, and / or a second protrusion is provided on the surface of the second conductive member facing the first conductive member.

[0009] Optionally, the first protrusion is spherical or strip-shaped; and / or the second protrusion is spherical or strip-shaped.

[0010] Optionally, a plurality of first protrusions are provided at intervals on a surface of the first conductive member facing the second conductive member; and / or a plurality of second protrusions are provided at intervals on a surface of the second conductive member facing the first conductive member.

[0011] Optionally, a plurality of first protrusions are arranged in an array on the first conductive member; and / or a plurality of second protrusions are arranged in an array on the second conductive member.

[0012] Optionally, the first protrusion and the second protrusion are arranged opposite to each other.

[0013] Optionally, the first conductive member and the second conductive member are respectively made of any one of pure metal, alloy, composite sheet with metal layer on the surface, graphite and carbon paper; and / or

[0014] The resistivity of the first conductive member and the second conductive member is less than 10-6Ω·m; and / or

[0015] The thickness of the first conductive member and the second conductive member is greater than 0.05 mm and less than 1 mm; and / or

[0016] The height of the first protrusion is less than 0.2 mm; and / or

[0017] The height of the second protrusion is less than 0.2 mm.

[0018] Optionally, the insulating layer is made of any one of EVA hot melt adhesive, TPU hot melt adhesive, PO hot melt adhesive, PA hot melt adhesive or PES hot melt adhesive; and / or

[0019] The melting point of the insulating layer is greater than or equal to 80° C. and less than or equal to 120° C.; and / or

[0020] The thickness of the insulating layer is greater than 0.01 mm and smaller than the height of the first protrusion or the second protrusion.

[0021] Optionally, the heat shrink sleeve is made of any one of polyethylene terephthalate PET, polyvinyl chloride PVC, polyethylene PE, polypropylene PP, PET, o-phenylphenol OPP, polyvinylidene fluoride PVDF, polyolefin POF or polytetrafluoroethylene PTFE; and / or the initial shrinkage temperature of the heat shrink sleeve is greater than or equal to 70°C and less than or equal to 110°C.

[0022] Optionally, the current limiting component includes: a current limiter and a current limiter lead, wherein the current limiter is connected to the second conductive member, and the current limiter lead is connected to the current limiter; the current limiter includes one of the following: a semiconductor, a diode, a resistor, and a resistance wire.

[0023] Optionally, a first groove is provided on the surface of the first conductive member facing the second conductive member, and / or a second groove is provided on the surface of the second conductive member facing the first conductive member, wherein the first groove is spaced apart from the first protrusion, and the second groove is spaced apart from the second protrusion.

[0024] Optionally, the grooves and protrusions on the first conductive member and the second conductive member are structures integrally formed with the conductive connecting member, or structures formed of other conductive materials.

[0025] According to another aspect of the present application, the present application also provides an electrochemical device, comprising: a first electrode, a second electrode and a safety structure in any of the above embodiments, wherein the first conductive member in the safety structure is connected to the first electrode; and the current limiting component in the safety structure is connected to the second electrode.

[0026] In the present application, a safety structure is provided, comprising: a first conductive member, a second conductive member, an insulating layer, a heat shrink sleeve and a current limiting component; the first conductive member, the insulating layer and the second conductive member are stacked in sequence, the melting point of the insulating layer is not higher than that of the first conductive member and the second conductive member, and the heat shrink sleeve is coated on the outside of the first conductive member and the second conductive member; the end of the first conductive member away from the insulating layer is electrically connected to the current limiting component; a first protrusion is provided on the surface of the first conductive member facing the second conductive member, and / or a second protrusion is provided on the surface of the second conductive member facing the first conductive member. By sandwiching hot melt adhesive between the conductive sheets of the concave-convex structure, and then wrapping the heat shrink sleeve on the "sandwich" structure, the heat shrink sleeve begins to shrink when it reaches a certain temperature, and applies pressure to the structure. The higher the temperature, the higher the degree of shrinkage, and the greater the pressure, so that the hot melt adhesive is completely removed in time. Then a current limiter is connected in series behind this structure to make the current flowing through the safety structure less than 1C current (battery capacity / 1 hour). It realizes the timely triggering of the battery to be electrically connected, and under the premise of not changing the internal resistance and battery capacity of the battery, it effectively improves the technical effect of the battery thermal runaway that is prone to occur when the lithium-ion battery encounters abuse such as high-temperature baking. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 is a structural schematic diagram of a safety structure according to an embodiment of the present application;

[0029] Figure 2 is a structural schematic diagram of a safety structure according to an embodiment of the present application;

[0030] Figure 3 is a structural schematic diagram of a safety structure according to an embodiment of the present application;

[0031] Figure 4 is a structural schematic diagram of a safety structure according to an embodiment of the present application;

[0032] Figure 5 is a schematic diagram of a protruding point on the surface of a conductive member according to an embodiment of the present application;

[0033] Figure 6 is a structural schematic diagram of a safety structure according to an embodiment of the present application;

[0034] Figure 7 The temperature-resistance curves of the controllers prepared with different hot melt adhesive films in the embodiment during the heating process of 5°C / min. DETAILED DESCRIPTION

[0035] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0037] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0038] Figure 1 is a schematic diagram of a security structure according to an embodiment of the present application, such as Figure 1 As shown, the safety structure includes: a first conductive member 10, a second conductive member 12, a heat shrink sleeve 14, a current limiting component 16 and an insulating layer 18, wherein:

[0039] The first conductive member 10 , the insulating layer 18 and the second conductive member 12 are stacked in sequence. The melting point of the insulating layer 18 is not higher than that of the first conductive member 10 and the second conductive member 12 . The heat shrink sleeve 14 is coated on the outside of the first conductive member 10 and the second conductive member 12 .

[0040] The insulating layer 18 is made of hot melt adhesive.

[0041] According to an optional embodiment of the present application, the first conductive member 10 and the second conductive member 12 are bonded by an insulating layer 18 (i.e., hot melt adhesive), and the hot melt adhesive is located between the first conductive member 10 and the second conductive member 12. The heat shrink sleeve 14 is coated on the outside of the first conductive member 10 and the second conductive member 12 to fix the first conductive member 10, the second conductive member 12 and the hot melt adhesive.

[0042] A first protrusion is disposed on a surface of the first conductive member 10 facing the second conductive member 12 , and / or a second protrusion is disposed on a surface of the second conductive member 12 facing the first conductive member 10 .

[0043] In the embodiment of the present application, the first conductive member 10 and the second conductive member 12 are both conductive sheets, such as Figure 1 As shown, the first conductive member 10 includes a flat area 101 , a protrusion 103 (accommodating spaces for accommodating melted hot melt adhesive are formed on both sides of the protrusion) and a groove 102 .

[0044] Figure 1 The concave-convex structure of the safety structure shown in the figure adopts a single-sided punching type (i.e., grooves and protrusions are arranged at intervals on a single surface at one end of the first conductive member 10). Figure 2 is a schematic diagram of another security structure according to an embodiment of the present application, such as Figure 2 As shown, the concave-convex structure of the first conductive member 10 is a double-sided punching type (ie, concave grooves and convex protrusions are arranged at intervals on the two surfaces of one end of the first conductive member 10).

[0045] Figure 3 In the safety structure shown, the concave-convex structure of the end of the second conductive member 12 in contact with the insulating layer 18 is single-sided punching (ie, grooves and protrusions are arranged at intervals on a single surface of one end of the second conductive member 12).

[0046] Figure 4 In the safety structure shown, the concave-convex structure of the end of the second conductive member 12 in contact with the insulating layer 18 is double-sided punching (ie, grooves and protrusions are arranged alternately on the two surfaces of one end of the second conductive member 12).

[0047] like Figure 1 or Figure 2 As shown, the insulating layer 18 is placed between the second conductive member 12 and the protruding point 103 of the first conductive member 10, and is bound by a heat shrink sleeve 14 to form a controller for realizing a temperature switch. The control principle is as follows:

[0048] When the ambient temperature reaches a certain temperature, the hot melt adhesive of the insulating layer 18 melts and softens. At this time, the heat shrink sleeve 14 shrinks and applies pressure to the first conductive member 10 and the second conductive member 12. The first conductive member 10 and the second conductive member 12 squeeze the melted and softened hot melt adhesive into the groove 102 of the first conductive member 10, and the protrusion 103 of the first conductive member 10 contacts the second conductive member 12, resulting in a short circuit.

[0049] One end of the first conductive member 10 away from the insulating layer 18 is electrically connected to the current limiting component 16 .

[0050] like Figure 1 or Figure 2 As shown, the current limiting component 16 is connected to the second conductive member 12, and its main function is to limit the current flowing through the safety structure within a certain range (for example, less than 1C current) after the safety structure is short-circuited, so that the temperature of the safety structure can be controlled, and the problem of overheating or even burning of the safety structure due to heat generation after a short circuit is avoided.

[0051] It should be noted that the current limiting component 16 may also be connected to the second conductive member 12 , which is not specifically limited here.

[0052] Through the above safety structure, hot melt adhesive is sandwiched between the conductive sheets of the concave-convex structure, and then a heat shrink sleeve is wrapped on the "sandwich" structure. When the heat shrink sleeve reaches a certain temperature, it begins to shrink and exerts pressure on the structure. The higher the temperature, the higher the degree of shrinkage and the greater the pressure, so that the hot melt adhesive is completely removed in time. Then a current limiter is connected in series behind this structure to make the current flowing through the safety structure less than 1C current (battery capacity / 1 hour). The timely triggering of the battery to make an electrical connection is achieved, and without changing the internal resistance and capacity of the battery, the technical effect of effectively improving the thermal runaway of lithium-ion batteries when they are abused by high-temperature baking is effectively improved.

[0053] According to an optional embodiment of the present application, the first protrusion is spherical or strip-shaped; and / or the second protrusion is spherical or strip-shaped.

[0054] As mentioned above, the first conductive member 10 and the second conductive member 12 are provided with protrusions. Figure 5 is a schematic diagram of a protruding point on the surface of a conductive member according to an embodiment of the present application, such as Figure 5 As shown, in the embodiment provided in the present application, the protrusions provided on the first conductive member 10 and the second conductive member 12 may be spherical protrusions or strip-shaped protrusions.

[0055] As an optional embodiment of the present application, a plurality of first protrusions are provided at intervals on the surface of the first conductive member 10 facing the second conductive member 12 ; and / or a plurality of second protrusions are provided at intervals on the surface of the second conductive member 12 facing the first conductive member 10 .

[0056] like Figure 5 As shown, there are multiple protrusions arranged on the first conductive member 10 and the second conductive member 12, and the height of the protrusions is less than 0.2 mm.

[0057] In another optional embodiment of the present application, a plurality of first protrusions are arranged in an array on the first conductive member 10 ; and / or a plurality of second protrusions are arranged in an array on the second conductive member 12 .

[0058] In the embodiment of the present application, the protrusions provided on the first conductive member 10 and the second conductive member 12 are arranged in an array, such as Figure 5 As shown, the following array arrangements may be included: a dot matrix structure, a stripe structure, and a grid structure.

[0059] By providing a plurality of protrusions, a plurality of accommodating spaces for accommodating melted hot melt adhesive can be formed, so that the hot melt adhesive can be completely removed in time and the battery can be triggered to be electrically connected in time.

[0060] As an optional embodiment of the present application, the first protrusion and the second protrusion are arranged opposite to each other.

[0061] The second conductive member 12 can be flat or have a concave-convex structure. When it has a concave-convex structure, its protrusions correspond to the protrusions of the first conductive member 10. Figure 3 and Figure 4 shown.

[0062] By arranging the protrusion of the first conductive member 10 and the protrusion of the second conductive member 12 correspondingly, the protrusions can be effectively prevented from interlocking with each other, thereby reducing the problem of accommodation space. It is also possible to completely remove the hot melt adhesive in time and trigger the battery to be electrically connected in time.

[0063] In the embodiment provided in the present application, the first conductive member 10 and the second conductive member 12 may be pure metal, or may be alloys or composite sheets with metal layers on the surface, graphite materials, carbon paper, etc.

[0064] The resistivity of the first conductive member 10 and the second conductive member 12 is less than 10 -6 Ω·m.

[0065] The thickness of the first conductive member 10 and the second conductive member 12 is greater than 0.05 mm and less than 1 mm.

[0066] The height of the first protrusion is less than 0.2 mm; the height of the second protrusion is less than 0.2 mm.

[0067] In some optional embodiments of the present application, the insulating layer 18 is made of any one of EVA hot melt adhesive, TPU hot melt adhesive, PO hot melt adhesive, PA hot melt adhesive or PES hot melt adhesive; and / or

[0068] The melting point of the insulating layer 18 is greater than or equal to 80° C. and less than or equal to 120° C.; and / or

[0069] The thickness of the insulating layer 18 is greater than 0.01 mm and smaller than the height of the first protrusion or the second protrusion.

[0070] In the embodiment of the present application, the hot melt adhesive of the insulating layer 18 is a polymer film with a melting point of 80-120° C., and is one of the following: EVA hot melt adhesive, TPU hot melt adhesive, PO hot melt adhesive, PA hot melt adhesive, PES hot melt adhesive. The thickness of the hot melt adhesive is greater than 0.01 mm and less than the protrusion height + 0.01 mm.

[0071] As an optional embodiment of the present application, the heat shrink sleeve 14 is made of any one of polyethylene terephthalate PET, polyvinyl chloride PVC, polyethylene PE, polypropylene PP, PET, o-phenylphenol OPP, polyvinylidene fluoride PVDF, polyolefin POF or polytetrafluoroethylene PTFE; and / or the initial shrinkage temperature of the heat shrink sleeve 14 is greater than or equal to 70°C and less than or equal to 110°C.

[0072] The heat shrink sleeve 14 in the embodiment of the present application is a heat shrink tube or is obtained by winding a heat shrink film, wherein the material of the heat shrink tube is polyethylene terephthalate PET or polyvinyl chloride PVC; the material of the heat shrink film is one of the following: polyethylene PE, polypropylene PP, PET, o-phenylphenol OPP, polyvinylidene fluoride PVDF, polyolefin POF and polytetrafluoroethylene PTFE.

[0073] The heat shrink sleeve 14 tightly wraps or binds the "sandwich" structure composed of the first conductive member 10, the second conductive member 12 and the hot melt adhesive. The heat shrinkage temperature of the heat shrink sleeve 14 is 70-100°C, and the heat shrinkage rate after heat shrinkage is greater than 1% / °C (heat shrinkage rate = length after shrinkage / length before shrinkage).

[0074] When the ambient temperature rises to 70°C, the heat shrink sleeve 14 starts to shrink and exerts pressure on the first conductive member 10 and the second conductive member 12, and the first conductive member 10 and the second conductive member 12 start to squeeze the hot melt adhesive. When the temperature further rises to 80°C, the hot melt adhesive starts to melt and soften, and the heat shrink sleeve 14 shrinks further, and the pressure exerted by the first conductive member 10 and the second conductive member 12 increases, so that the softened hot melt adhesive is squeezed into the groove 102 of the first conductive member 10. At this time, the protrusion 103 contacts the second conductive member 12, and the contact resistance is below 200mΩ.

[0075] This structure can accurately control the short circuit of lithium-ion batteries at 75-90°C, and the current after the short circuit is strictly limited to a specified range. It achieves the technical effect of effectively improving the thermal runaway of lithium-ion batteries when they are abused by high-temperature baking without changing the internal resistance and capacity of the battery.

[0076] like Figure 1 to Figure 4 As shown, the current limiting component 16 in the embodiment of the present application includes: a current limiter 160 and a current limiter lead 162, wherein the current limiter 160 is connected to the second conductive member 12, and the current limiter lead 162 is connected to the current limiter 160; the current limiter 160 includes one of the following: a semiconductor, a diode, a resistor, and a resistance wire. The current in the current limiter 160 is controlled at a battery rate of 0.1C to 1C.

[0077] In the embodiments of the present application, the semiconductor refers to a temperature-sensitive resistor, the resistance value of which changes with the change of temperature.

[0078] Resistors, generally referred to as resistors, are current limiting components. When a resistor is connected to a circuit, the resistance value of the resistor is fixed, usually with two pins, and it can limit the current through the branch it is connected to.

[0079] Resistance wire is an electrical component that converts electrical energy into heat energy and is usually made of high-resistance alloys.

[0080] By connecting a current limiter in series behind the safety structure so that the current flowing through the safety structure is less than 1C current (battery capacity / 1 hour), the heat generated inside the battery can be reduced, preventing the lithium-ion battery from rapidly heating up when it encounters abuse such as high-temperature baking, which can easily cause thermal runaway of the battery.

[0081] In some optional embodiments of the present application, a first groove is provided on the surface of the first conductive member 10 facing the second conductive member 12, and / or a second groove is provided on the surface of the second conductive member 12 facing the first conductive member 10, wherein the first groove is spaced apart from the first protrusion, and the second groove is spaced apart from the second protrusion.

[0082] As mentioned above, Figures 1 to 4 As shown, projections and grooves are arranged at intervals on the surfaces of the first conductive member 10 and the second conductive member 12. Providing the grooves next to the projections can increase the accommodation space for accommodating the melted hot melt adhesive.

[0083] According to an optional embodiment of the present application, the grooves and protrusions on the first conductive member 10 and the second conductive member 12 are structures integrally formed with the conductive members, or structures formed of other conductive materials.

[0084] Figure 6 is a schematic diagram of a security structure according to an embodiment of the present application, such as Figure 6 As shown, the grooves and protrusions on the surface of the first conductive member 10 (here only the first conductive member 10 is taken as an example, and the second conductive member 12 is the same) are made of other conductive materials.

[0085] The grooves and protrusions on the conductive member are set to be a structure integrally formed with the conductive member, and the protrusions on the conductive member are not easily damaged, which can increase the service life of the conductive member. However, setting the protrusions on the conductive member as protrusions made of other materials can increase the diversity of the conductor design. For example, the conductive sheet of the conductive member is made of iron, and the protrusions are made of alloy materials. The alloy material has better conductivity than iron and can better meet the electrical connection requirements of lithium-ion batteries.

[0086] The effects of the safety structure proposed in this application are described below in conjunction with several specific embodiments and comparative examples:

[0087] Example 1

[0088] A nickel metal sheet 1 with a single-sided protrusion of 0.1mm is obtained by punching, and the nickel metal sheet 2 and the lead are welded to the two ends of the 1.5Ω resistor respectively. A hot melt adhesive film (thickness 0.05mm, TPU, melting point 90℃, initial softening temperature 80℃) is attached to the surface of the nickel metal sheet 2 and covers one end and the side edge thereof and is assembled into a "sandwich" structure with the nickel metal sheet 1 with a protrusion of 0.1mm obtained by punching. Two circles of heat shrink film (the heat shrink film is POF, the initial shrinkage temperature is 70℃, and the thickness is 0.012mm) are wrapped around the sandwich structure and fixed with tape or glue to prepare a controller. The nickel metal sheet at one end of the controller is welded to the resistor (1.5Ω), and the prepared safety structure is connected to the positive and negative electrodes of the use end. The hot melt adhesive film is set between the raised part of the nickel metal sheet 1 and the nickel metal sheet 2, and it acts as an insulation between 1 and 2 below the initial softening temperature (softening temperature < melting temperature). When the ambient temperature reaches the initial softening temperature of 80°C, the sol is squeezed into the groove point under the shrinkage force of the heat shrink film, and the raised point is electrically connected to the nickel metal sheet 2. Its resistance decreases with the increase of temperature, and the final stable point is below 10mΩ. The current passing through the safety mechanism component is limited to a certain range through the current limiting resistor so as not to burn the device.

[0089] When this safety structure is applied to battery products (such as lithium-ion batteries), it is set between the two pole ears of the battery, which can greatly improve the battery's performance in passing the oven temperature baking safety test. Moreover, there is no need to change the positive electrode material, negative electrode material and electrolyte, thereby avoiding side effects such as increased battery internal resistance and decreased capacity.

[0090] Example 2

[0091] The same as the first embodiment, except that the concavo-convex structure of the nickel metal sheet 1 is double-sided punched.

[0092] Example 3

[0093] The same as Example 1, except that the concavo-convex structure of the nickel metal sheet is coated with copper powder with a particle size of 10 μm and a coating thickness of 0.1 mm.

[0094] Example 4

[0095] The same as Example 1, except that the hot melt adhesive film is changed from PO film to EVA (melting point 70° C.), and the current limiter resistance is 2.5Ω.

[0096] Example 5

[0097] The same as Example 1, except that the hot melt adhesive film is changed from PO film to TPU (melting point 105° C.), and the current limiter resistance is 1Ω.

[0098] Example 6

[0099] The same as Example 1, except that the hot melt adhesive film is changed from PO film to PA (melting point 105° C.), and the current limiter resistance is 0.5Ω.

[0100] Example 7

[0101] The same as Example 1, except that the hot melt adhesive film is changed from PO film to PES (melting point 120° C.), and the current limiter resistance is 0.5Ω.

[0102] Example 8

[0103] The same as Example 1, except that the conductive sheet is changed from a nickel sheet to a copper sheet, and the current limiter resistance is 2Ω.

[0104] Example 9

[0105] The same as Example 1, except that the conductive sheet is changed from a nickel sheet to an aluminum sheet, and the current limiter resistance is 1.7Ω.

[0106] Example 10

[0107] The same as Example 1, except that the conductive sheet is changed from nickel sheet to stainless steel, and the current limiter resistance is 1.5Ω.

[0108] Embodiment 11

[0109] The same as the embodiment 2, except that one end of the nickel metal sheet 2 also adopts a single-sided punched concave-convex structure, and the convex points of the nickel metal sheet 1 and the nickel metal sheet 2 correspond to each other.

[0110] Example 12

[0111] The same as the embodiment 2, except that one end of the nickel metal sheet 2 adopts a double-sided punched concave-convex structure, and the convex points of the nickel metal sheet 1 and the nickel metal sheet 2 correspond to each other.

[0112] Comparative Example 1

[0113] The same as Example 1, except that the conductive sheet is not treated with concave-convex, and both conductive sheets are flat and smooth nickel sheets.

[0114] Comparative Example 2

[0115] The same as the first embodiment, except that the concave and convex points of the conductive sheet are made of hard carbon.

[0116] Comparative Example 3

[0117] The same as Example 1, except that the current limiting resistor is not connected.

[0118] Table 1 shows the experimental parameters and related test results of each embodiment and comparative example

[0119] Table 1

[0120]

[0121]

[0122] Figure 7 The temperature-resistance curve of the controller prepared with different hot-melt adhesive films in the embodiment during the heating process of 5°C / min. It can be seen from the embodiment and the comparative example that the higher the melting temperature of the hot-melt adhesive film, the higher the trigger temperature, and the resistance after triggering is also relatively high. This is mainly caused by the poor fluidity of the hot-melt adhesive film with a high melting temperature after triggering melting. The copper powder particle coating has a relatively delayed triggering temperature because its concave and convex points are not prominent enough. The copper particles are in point contact and the resistance will be relatively large due to the integration of the hot-melt adhesive, but it can also achieve the goal of short circuit and improve the furnace temperature pass rate. Compared with comparative example 1, due to the flat surface of the nickel sheet, the short circuit phenomenon is still not triggered after the temperature rises to 150°C, while comparative example 2 uses hard carbon with poorer conductivity, which has a later triggering temperature and a larger short-circuit resistance, but still has a pass rate of 5%. In comparative example 3, no resistor or other current limiter is connected. After the short circuit is triggered, the controller is powered on. Due to the lack of current limit, the controller burns quickly and cannot be discharged continuously, resulting in battery failure.

[0123] According to another aspect of the present application, the present application also provides an electrochemical device, comprising: a first electrode, a second electrode and a safety structure in any of the above embodiments, wherein the first conductive member in the safety structure is connected to the first electrode; and the current limiting component in the safety structure is connected to the second electrode.

[0124] It is understandable that the electrochemical device includes all the technical effects of the above safety structure. Since the technical effects of the safety structure have been described in detail above, they will not be repeated here.

[0125] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0126] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0127] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A safety structure, characterized in that: include: A first conductive member, a second conductive member, an insulating layer, a heat shrink sleeve, and a current limiting component; The first conductive member, the insulating layer and the second conductive member are stacked in sequence, the melting point of the insulating layer is not higher than that of the first conductive member and the second conductive member, and the heat shrink sleeve is coated on the outside of the first conductive member and the second conductive member; One end of the first conductive member away from the insulating layer is electrically connected to the current limiting component; A first protrusion is provided on a surface of the first conductive member facing the second conductive member, and / or a second protrusion is provided on a surface of the second conductive member facing the first conductive member.

2. The safety structure according to claim 1, characterized in that: The first protrusion is spherical or strip-shaped; and / or the second protrusion is spherical or strip-shaped.

3. The safety structure according to claim 1 or 2, characterized in that: A plurality of first protrusions are arranged at intervals on a surface of the first conductive member facing the second conductive member; and / or A plurality of second protrusions are arranged at intervals on a surface of the second conductive member facing the first conductive member.

4. The safety structure according to claim 3, characterized in that: A plurality of the first protrusions are arranged in an array on the first conductive member; and / or A plurality of the second protrusions are arranged in an array on the second conductive member.

5. The safety structure according to claim 1, characterized in that: The first protrusion is arranged opposite to the second protrusion.

6. The safety structure according to claim 1, characterized in that: The first conductive member and the second conductive member are respectively made of any one of pure metal, alloy, composite sheet with metal layer on the surface, graphite and carbon paper; and / or The resistivity of the first conductive member and the second conductive member is less than 10 -6 Ω·m; and / or The thickness of the first conductive member and the second conductive member is greater than 0.05 mm and less than 1 mm; and / or The height of the first protrusion is less than 0.2 mm; and / or The height of the second protrusion is less than 0.2 mm.

7. The safety structure according to claim 1, characterized in that: The insulating layer is made of any one of EVA hot melt adhesive, TPU hot melt adhesive, PO hot melt adhesive, PA hot melt adhesive or PES hot melt adhesive; and / or The melting point of the insulating layer is greater than or equal to 80° C. and less than or equal to 120° C.; and / or The thickness of the insulating layer is greater than 0.01 mm and smaller than the height of the first protrusion or the second protrusion.

8. The safety structure according to claim 1, characterized in that: The heat shrink sleeve is made of any one of polyethylene terephthalate PET, polyvinyl chloride PVC, polyethylene PE, polypropylene PP, PET, o-phenylphenol OPP, polyvinylidene fluoride PVDF, polyolefin POF or polytetrafluoroethylene PTFE; and / or The initial shrinkage temperature of the heat shrink sleeve is greater than or equal to 70°C and less than or equal to 110°C.

9. The safety structure according to claim 1, characterized in that: The current limiting assembly comprises: a current limiter and a current limiter lead, wherein the current limiter is connected to the second conductive member, and the current limiter lead is connected to the current limiter; The current limiter includes one of the following: a semiconductor, a diode, a resistor and a resistance wire.

10. The safety structure according to claim 1, characterized in that: A first groove is provided on the surface of the first conductive member facing the second conductive member, and / or a second groove is provided on the surface of the second conductive member facing the first conductive member, wherein the first groove is spaced apart from the first protrusion, and the second groove is spaced apart from the second protrusion.

11. The safety structure according to claim 1, characterized in that: The grooves and protrusions on the first conductive member and the second conductive member are structures formed integrally with the conductive connecting member, or are structures formed of other conductive materials.

12. An electrochemical device, characterized in that: include: A first electrode, a second electrode, and a safety structure according to any one of claims 1 to 11, wherein: The first conductive member in the safety structure is connected to the first electrode; The current limiting component in the safety structure is connected to the second electrode.

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