Electrochemical device and electronic device

Abstract

An electrochemical device includes an electrode assembly. The electrode assembly has a wound structure and includes a first electrode, a second electrode, and a separator disposed between the first and second electrodes. The first electrode includes a first current collector and a first active material layer, the first current collector including a first empty foil region. The second electrode includes a second current collector and a second active material layer, the second current collector including a second empty foil region. The first empty foil region includes a first region located on the outermost layer of the first electrode. The second empty foil region includes a second region located on the outermost layer of the second electrode. The electrochemical device further includes an adhesive component, the adhesive component including a laminated adhesive layer and a metal layer, the adhesive layer including a conductive material, the adhesive component bonding at least one of the first and second regions through the adhesive layer. This application also provides an electronic device. This application can improve the safety and reliability of electrochemical devices.

Description

Technical Field

[0001] This application relates to the field of energy storage devices, and in particular to an electrochemical device and an electronic device. Background Technology

[0002] Electrochemical devices (such as batteries) are widely used in electronic mobile devices, power tools, and electric vehicles. To improve the pass rate of safety tests such as needle penetration and heavy object impact, elongated positive and negative empty foil areas can be set at the tail of the electrode assembly, so that a vest structure can be formed on the outer ring of the electrode assembly after winding. When an external sharp conductor punctures the electrochemical device, a short circuit can quickly occur between the elongated positive and negative empty foil areas, causing the electrochemical device to discharge.

[0003] However, the pass rate for safety tests of existing electrochemical devices remains low. Summary of the Invention

[0004] To address the above shortcomings, it is necessary to provide an electrochemical device.

[0005] Furthermore, it is also necessary to provide an electronic device having the aforementioned electrochemical device.

[0006] This application provides an electrochemical device including an electrode assembly. The electrode assembly is a wound structure, including a first electrode, a second electrode, and a separator disposed between the first electrode and the second electrode. The first electrode includes a first current collector and a first active material layer disposed on the surface of the first current collector, the first current collector including a first empty foil region without the first active material layer. The second electrode includes a second current collector and a second active material layer disposed on the surface of the second current collector, the second current collector including a second empty foil region without the second active material layer. The first empty foil region includes a first region located on the outermost layer of the first electrode. The second empty foil region includes a second region located on the outermost layer of the second electrode. The electrochemical device further includes an adhesive member, the adhesive member including an adhesive layer and a metal layer stacked together. The adhesive layer includes a conductive material. The adhesive member adheres to at least one of the first region and the second region through the adhesive layer.

[0007] In this application, when the electrochemical device suffers mechanical abuse (such as needle puncture or heavy object impact), the first and second regions can be made conductive through the adhesive connector and short-circuited, diverting the short-circuit current within the electrode assembly and causing the electrochemical device to discharge, thus reducing the risk of fire or explosion. Simultaneously, the adhesive connector can improve the mechanical strength of the first and / or second regions, reducing the risk of high-temperature melting at the short-circuit point. This allows the electrochemical device to continuously short-circuit through the aforementioned short-circuit point even under mechanical abuse, thereby improving the safety and reliability of the electrochemical device. Furthermore, since the adhesive connector is only located on at least one of the first and second regions, it also reduces the impact on the energy density of the electrochemical device.

[0008] In some possible implementations, along the winding direction of the electrode assembly, the first region includes a first segment, a first bent segment, a second segment, and a second bent segment connected in sequence. An adhesive is disposed on the surfaces of the first and second segments. Therefore, when the electrochemical device is punctured from either the first or second segment (especially when the puncture depth is less than the thickness of the electrochemical device) or impacted by a heavy object, the first and second regions can short-circuit at contact, reducing the risk of melting at the short-circuit point. Particularly in some embodiments where the first region is aluminum foil, the adhesive can reduce the risk of the aluminum foil melting at the short-circuit point due to high temperature during puncture. Furthermore, when a foreign object completely penetrates the electrochemical device, the adhesive increases the number of short-circuit points within the electrode assembly that can cause a sustained short circuit, facilitating faster shunting of the short-circuit current within the electrode assembly and improving the safety and reliability of the electrochemical device.

[0009] In some possible implementations, the adhesive is also disposed on the surface of at least one of the first and second bends. Therefore, when the electrochemical device is punctured or struck by a heavy object from the first or second bend, the first and second regions can be short-circuited, and the risk of melting at the short-circuit point is reduced, allowing the electrochemical device to continuously short-circuit through the aforementioned short-circuit point, further improving safety and reliability.

[0010] In some possible implementations, along the winding direction of the electrode assembly, the second region includes a third bend, a third section, a fourth bend, and a fourth section connected in sequence. Adhesives are disposed on the surfaces of the third and fourth sections. Therefore, when the electrochemical device is punctured from the third or fourth section side (especially when the puncture depth is less than the thickness of the electrochemical device) or impacted by a heavy object, the first and second regions can short-circuit, reducing the risk of melting at the short-circuit point. Particularly when the second region is copper foil in some embodiments, the adhesive bonded to the copper foil surface significantly improves the mechanical strength of the jacket structure. Thus, during a heavy impact, the copper foil can maintain a large contact area with the aluminum foil, diverting the short-circuit current within the electrode assembly. Furthermore, when a foreign object completely penetrates the electrochemical device, the adhesive increases the number of short-circuit points within the electrode assembly that can cause a sustained short circuit, facilitating faster diversion of the short-circuit current and improving the safety and reliability of the electrochemical device.

[0011] In some possible implementations, the adhesive is also disposed on the surface of at least one of the third and fourth bends. Therefore, when the electrochemical device is punctured or struck by a heavy object from the third or fourth bend, a short circuit can be made between the first and second regions, and the risk of melting at the short circuit point can be reduced.

[0012] In some possible implementations, along the winding direction of the electrode assembly, the adhesive members disposed in the first region and the adhesive members disposed in the second region are located on different sides of the winding center of the electrode assembly. In this case, if the electrochemical device is punctured or struck by a heavy object from different sides of the winding center, the first region and the second region can be short-circuited, and the risk of melting at the short-circuit point is reduced. This allows the electrochemical device to continuously short-circuit through the aforementioned short-circuit point, improving safety and reliability.

[0013] In some possible implementations, along the winding direction of the electrode assembly, the adhesive in the first region and the adhesive in the second region are located on the same side of the winding center of the electrode assembly. In this case, when a foreign object passes through or a heavy object impacts the first and second regions where the adhesive is located, the adhesive can simultaneously increase the mechanical strength of both regions at the same short-circuit point, further reducing the risk of short-circuit point melting and improving the safety and reliability of the electrochemical device.

[0014] In some possible implementations, the electrode assembly further includes a first tab and a second tab. The first tab is electrically connected to a first current collector, and the second tab is electrically connected to a second current collector. The adhesive has a first recess and a second recess. In the thickness direction of the electrode assembly, the projection of the first recess in a first region overlaps the projection of the first tab in the first region, and the projection of the second recess in the first region overlaps the projection of the second tab in the first region. Therefore, the total thickness of the electrode assembly at the locations corresponding to the first and second tabs is reduced, compensating for the increase in the total thickness of the electrochemical device caused by the adhesive, which is beneficial for improving energy density.

[0015] In some possible implementations, the adhesive layer includes at least one of conductive silver paste or conductive silicone, giving the adhesive layer high conductivity and adhesion. In some possible implementations, the metal layer includes at least one of copper, aluminum, titanium, or nickel, giving the metal layer high conductivity.

[0016] In some possible implementations, the thickness of the adhesive layer is 4 to 10 micrometers. This increases the bonding reliability of the adhesive layer while reducing the impact on the energy density of the electrochemical device when the adhesive layer is too thick. In some possible implementations, the thickness of the metal layer is 4 to 20 micrometers. This increases the mechanical strength of the first and / or second regions while reducing the impact on the energy density of the electrochemical device when the metal layer is too thick.

[0017] In some possible implementations, the first region is located at the outermost ring of the electrode assembly, and the second region is located at the second outermost ring of the electrode assembly. By setting the first region as the termination section, on the one hand, the first current collector can increase the hardness of the electrode assembly; on the other hand, when the second current collector is copper foil in some embodiments, it also reduces the risk of the electrolyte easily corroding the second current collector at the termination point.

[0018] A second aspect of this application also provides an electronic device that includes the electrochemical device described above. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0020] Figure 1 A front view of an electrochemical device provided according to an embodiment of this application.

[0021] Figure 2 for Figure 1 Top view of the electrode assembly of the electrochemical device shown in some embodiments.

[0022] Figure 3 for Figure 2 A schematic diagram of the unfolded first electrode of the electrode assembly shown.

[0023] Figure 4 for Figure 2 A schematic diagram of the unfolded second electrode of the electrode assembly shown.

[0024] Figure 5 for Figure 2 A cross-sectional view of the adhesive component of the electrochemical device shown.

[0025] Figure 6 for Figure 3 The back view of the first electrode shown.

[0026] Figure 7 for Figure 1 Top view of the electrode assembly of the electrochemical device shown in some other embodiments.

[0027] Figure 8 for Figure 1 Top view of the electrode assembly of the electrochemical device shown in some other embodiments.

[0028] Figure 9 for Figure 1 Top view of the electrode assembly of the electrochemical device shown in some other embodiments.

[0029] Figure 10 for Figure 1 Top view of the electrode assembly of the electrochemical device shown in some other embodiments.

[0030] Figure 11 for Figure 1 Top view of the electrode assembly of the electrochemical device shown in some other embodiments.

[0031] Figure 12 for Figure 1 Top view of the electrode assembly of the electrochemical device shown in some other embodiments.

[0032] Figure 13 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application.

[0033] Explanation of main component symbols

[0034] Electronic device 1

[0035] Casing 10

[0036] First shell 11

[0037] Second shell 12

[0038] Electrode assembly 20

[0039] First Extreme Film 21

[0040] Second pole piece 22

[0041] Separator 23

[0042] First ear 30

[0043] Second pole ear 40

[0044] Adhesive parts 50

[0045] Adhesive layer 50a

[0046] Metal layer 50b

[0047] 1st recessed part 50c

[0048] 2nd recessed part 50d

[0049] First adhesive component 51

[0050] Second adhesive component 52

[0051] Third adhesive component 53

[0052] Fourth adhesive component 54

[0053] Fifth adhesive component 55

[0054] Sixth adhesive component 56

[0055] Electrochemical device 100

[0056] First current collector 210

[0057] First active material layer 211

[0058] First empty foil area 212

[0059] Second current collector 220

[0060] Second active material layer 221

[0061] Second empty foil area 222

[0062] Edge 500

[0063] First area 2120

[0064] First paragraph 2121

[0065] First bend section 2122

[0066] Second paragraph 2123

[0067] Second bend section 2124

[0068] Third District 2125

[0069] Fourth District 2126

[0070] Second Zone 2220

[0071] Third paragraph 2221

[0072] Third bend section 2222

[0073] Fourth paragraph 2223

[0074] Fourth bend segment 2224

[0075] Winding direction D

[0076] Winding center O

[0077] First direction X

[0078] Second direction Y

[0079] Third direction Z

[0080] Thicknesses T1 and T2 Detailed Implementation

[0081] The technical solutions in the embodiments of this application are described clearly and in detail below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0082] The embodiments of this application will be described in detail below. However, this application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided to provide a thorough and detailed understanding of this application to those skilled in the art.

[0083] Additionally, for brevity and clarity, the dimensions or thicknesses of various components and layers may be enlarged in the accompanying drawings. Throughout the text, the same numerical values ​​refer to the same elements. As used herein, the terms "and / or" and "and / or" include any and all combinations of one or more of the associated enumerated items. Furthermore, it should be understood that when element A is referred to as "connecting" element B, element A may be directly connected to element B, or there may be an intermediate element C and element A and element B may be indirectly connected to each other.

[0084] Furthermore, when describing the implementation of this application, the word "may" refers to "one or more implementations of this application".

[0085] The technical terms used herein are for the purpose of describing particular embodiments and are not intended to limit this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It should be further understood that the term "comprising," as used in this specification, means the presence of the described features, values, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, values, steps, operations, elements, components, and / or combinations thereof.

[0086] Spatial terms used herein, such as "above," are used for convenience in describing the relationship between one element or feature and another element (or feature) or feature (or feature) illustrated in the figures. It should be understood that, in addition to the directions depicted in the figures, spatial terms are intended to include different orientations of the device or apparatus during use or operation. For example, if the device in the figure is flipped, an element described as "above" or "on" other elements or features will be oriented "below" or "under" other elements or features. Therefore, the exemplary term "above" can include both above and below orientations. It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Therefore, a first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.

[0087] Please see Figure 1 and Figure 2 This application provides an electrochemical device 100, including a housing 10 and an electrode assembly 20 disposed within the housing 10. In some embodiments, the electrochemical device 100 is a pouch battery. The housing 10 can be a packaging bag encapsulated with an encapsulation film, i.e., the electrochemical device 100 is a pouch battery. In other embodiments, the electrochemical device 100 can also be a steel-cased battery or an aluminum-cased battery, and this application is not limited thereto.

[0088] The electrode assembly 20 has a wound structure, including a first electrode 21, a second electrode 22, and a separator 23 disposed between the first electrode 21 and the second electrode 22. The separator 23 is used to prevent the first electrode 21 and the second electrode 22 from directly contacting each other, thereby reducing the possibility of short circuits between the first electrode 21 and the second electrode 22. The electrochemical device 100 also includes a first tab 30 and a second tab 40. The first tab 30 is electrically connected to the first electrode 21, and the second tab 40 is electrically connected to the second electrode 22. The first tab 30 and the second tab 40 extend from one end of the housing 10 to connect to an external device (not shown). A three-dimensional coordinate system is established based on a first direction X, a second direction Y, and a third direction Z that are perpendicular to each other. In this application, the first direction X is the direction from the first tab 30 to the second tab 40; the second direction Y is the direction in which the first tab 30 and the second tab 40 extend out of the electrode assembly 20, or the direction of the winding center O of the electrode assembly 20; and the third direction Z is the thickness direction of the electrode assembly 20. In this assembly, the first electrode 21, the separator 23, and the second electrode 22 are stacked sequentially and then wound around a winding center O to form the electrode assembly 20. For example, the stack 2 can be wound counterclockwise (winding direction D) around the winding center O to form the electrode assembly 20. In some embodiments, the first electrode 21 can be a positive electrode and the second electrode 22 can be a negative electrode. In other embodiments, the first electrode 21 can be a negative electrode and the second electrode 22 can be a positive electrode.

[0089] like Figure 2 and Figure 3 As shown, the first electrode 21 includes a first current collector 210 and a first active material layer 211 respectively disposed on opposite surfaces of the first current collector 210. The first current collector 210 has a current collection function; for example, the first current collector 210 may contain aluminum or nickel. In some embodiments, the first current collector 210 contains aluminum. The first active material layer 211 contains an active material, such as at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxide, lithium-rich manganese-based materials, or lithium nickel cobalt aluminum oxide.

[0090] The first current collector 210 includes a first empty foil region 212, neither of which has a first active material layer 211. The first empty foil region 212 includes a first region 2120, which is located on the outermost layer of the first electrode 21. Further, in some embodiments, the first region 2120 is located on the outermost ring of the electrode assembly 20. By setting the first region 2120 as a finishing section, on the one hand, the first current collector 210 can increase the hardness of the electrode assembly 20, thereby protecting the electrode assembly 20 and reducing the risk of failure or damage when the electrochemical device 100 is dropped; on the other hand, it reduces the risk that the electrolyte may easily corrode the second current collector 220 (such as copper foil) when the second current collector 220 is finished. In some embodiments, along the winding direction D of the electrode assembly 20, the first region 2120 includes a first segment 2121, a first bent segment 2122, a second segment 2123, and a second bent segment 2124 connected in sequence. The first segment 2121 and the second segment 2123 can both be straight segments. At this point, the direction Z of the third party is also the direction from the first segment 2121 to the second segment 2123. In other embodiments, the first segment 2121 and the second segment 2123 may also be bends.

[0091] like Figure 2 and Figure 4 As shown, the second electrode 22 includes a second current collector 220 and a second active material layer 221 disposed on the surface of the second current collector 220. The second current collector 220 has a current collection function; for example, the second current collector 220 may contain copper, nickel, or a carbon-based conductive material. In some embodiments, the second current collector 220 contains copper. The second active material layer 221 contains an active material, which may be selected from at least one of graphite-based materials, alloy-based materials, lithium metal, and alloys thereof. Graphite-based materials may be selected from at least one of artificial graphite and natural graphite; alloy-based materials may be selected from at least one of silicon, silicon oxide, tin, and titanium sulfide.

[0092] The second current collector 220 includes a second empty foil region 222, neither of which has a second active material layer 221. The second empty foil region 222 includes a second region 2220, which is located on the outermost layer of the second electrode 22. In some embodiments, along the winding direction D of the electrode assembly 20, the second region 2220 includes a third bent segment 2222, a third segment 2221, a fourth bent segment 2224, and a fourth segment 2223 connected in sequence. The third segment 2221 and the fourth segment 2223 may both be straight segments. In other embodiments, the third segment 2221 and the fourth segment 2223 may also be bent segments.

[0093] like Figure 2As shown, in the third direction Z, the first segment 2121, the third segment 2221, the fourth segment 2223, and the second segment 2123 are arranged sequentially and opposite to each other. Viewed from the second direction Y, the first segment 2121 and the third segment 2221 are located on the same side of the winding center O, while the second segment 2123 and the fourth segment 2223 are both located on the other side of the winding center O. In the first direction X, the second bent segment 2124, the third bent segment 2222, the fourth bent segment 2224, and the first bent segment 2122 are arranged sequentially and opposite to each other. Viewed from the second direction Y, the second bent segment 2124 and the third bent segment 2222 are both located on the same side of the winding center O, while the first bent segment 2122 and the fourth bent segment 2224 are both located on the other side of the winding center O.

[0094] In this application, "outermost layer" refers to the fact that when the first electrode 21 is wound along the winding direction D, the first region 2120 is located at the outermost edge or outermost ring of the wound first electrode 21; and when the first electrode 21 is wound along the winding direction D, the second region 2220 is located at the outermost edge or outermost ring of the wound second electrode 22.

[0095] In some embodiments, the first region 2120 is located at the outermost ring of the electrode assembly 20, and the second region 2220 is located at the second outermost ring of the electrode assembly 20.

[0096] At least a portion of the second region 2220 is disposed opposite to the first region 2120 through the isolation membrane 23. In some embodiments, the third segment 2221 is disposed opposite to the first segment 2121 through the isolation membrane 23, the fourth bent segment 2224 is disposed opposite to the first bent segment 2122 through the isolation membrane 23, and the fourth segment 2223 is disposed opposite to the second segment 2123 through the isolation membrane 23. Thus, the first region 2120, the second region 2220, and the separator 23 disposed between the first region 2120 and the second region 2220 can jointly form the vest (MJ) structure of the electrode assembly 20. This vest structure is the part of the electrochemical device 100 most prone to short circuits during mechanical abuse (e.g., during needle puncture, a foreign object pierces the first region 2120, the separator 23, and the second region 2220, causing a short circuit; or during impact, the separator 23 contracts or ruptures, causing a short circuit). In some embodiments, the first empty foil region 212 may further include a third region 2125 and a fourth region 2126, which are sequentially connected in the winding direction D. Therefore, the first empty foil region 212 forms more than one turn around the first electrode 21. In some embodiments, the second empty foil region 222 includes only the second region 2220. Therefore, the second empty foil region 222 forms exactly one loop outside the second electrode 22. In this application, "one loop" means starting from a point on the winding structure as the starting end, going around the winding direction D to another point as the ending end, and the ending end and the starting end are on the same straight line along the third direction Z.

[0097] like Figure 2 and Figure 3 As shown, the electrochemical device 100 also includes an adhesive component 50. Please refer to [the diagram / reference]. Figure 5 The adhesive component 50 includes an adhesive layer 50a and a metal layer 50b stacked together. The adhesive layer 50a includes a conductive material, and the adhesive component 50 is bonded to at least one of the first region 2120 and the second region 2220 through the adhesive layer 50a. Since the adhesive component 50 is made entirely of conductive material, when the electrochemical device 100 is subjected to mechanical abuse (such as needle puncture or impact from a heavy object), the first region 2120 and the second region 2220 can make contact and conduct through the adhesive component 50, and a short circuit can be quickly formed, diverting the short-circuit current in the electrode assembly 20, causing the electrochemical device 100 to discharge, and reducing the risk of fire or explosion of the electrochemical device 100. At the same time, the adhesive component 50 can improve the mechanical strength of the first region 2120 and / or the second region 2220, reducing the risk of high-temperature melting at the short circuit point, so that the electrochemical device 100 can continue to short-circuit through the short circuit point when subjected to the above-mentioned mechanical abuse, thereby improving safety and reliability.

[0098] Furthermore, in the prior art, to reduce the risk of short-circuit melting between the first and second empty foil areas during mechanical abuse such as needle puncture or heavy object impact, the contact resistance can be increased by increasing the thickness of the current collector or by adding a base coating to the surface of the first current collector. However, the adhesive 50 of this application is only disposed on at least one of the first region 2120 and the second region 2220, which not only reduces the risk of high-temperature melting at the short-circuit point during mechanical abuse but also reduces the impact on the energy density of the electrochemical device 100.

[0099] like Figure 2 As shown, in some embodiments, the adhesive 50 is disposed on the first region 2120. Further, in some embodiments, viewed from the second direction Y, along the winding direction D, the adhesive 50 disposed on the first region 2120 is located on different sides of the winding center O. For example, the adhesive 50 disposed on the first region 2120 is located on different sides of the winding center O in the third direction Z. In this case, if the electrochemical device 100 is punctured from different sides of the winding center O (especially when the puncture depth is less than the thickness of the electrochemical device 100, such as a puncture depth of 50% of the thickness of the electrochemical device 100, i.e., shallow puncture) or impacted by a heavy object, the first region 2120 and the second region 2220 can short-circuit, and the risk of melting at the short-circuit point is reduced. Moreover, when a foreign object completely penetrates the electrochemical device 20 (e.g., the puncture depth is 100% of the thickness of the electrochemical device 100, i.e., full penetration), the adhesive 50 located on different sides of the winding center O increases the number of short-circuit points in the electrode assembly 20 that can cause a continuous short circuit. This helps to divert the short-circuit current in the electrode assembly 20 more quickly, further reducing the risk of fire or explosion of the electrochemical device 100 and improving the safety and reliability of the electrochemical device 100.

[0100] In some embodiments, the adhesive layer 50a comprises at least one of conductive silver paste or conductive silicone, thereby giving the adhesive layer 50a high conductivity and adhesion. In some embodiments, the metal layer 50b comprises at least one of copper, aluminum, titanium, or nickel, thereby giving the metal layer 50b high conductivity.

[0101] like Figure 5 As shown, in some embodiments, the thickness T1 of the adhesive layer 50a is 4 micrometers to 10 micrometers. This increases the reliability of the adhesive layer 50a in bonding to the first region 2120 and / or the second region 2220 while reducing the impact on the energy density of the electrochemical device 100 when the adhesive layer 50a is too thick. In some embodiments, the thickness T2 of the metal layer 50b is 4 micrometers to 20 micrometers. This increases the mechanical strength of the first region 2120 and / or the second region 2220 while reducing the impact on the energy density of the electrochemical device 100 when the metal layer 50b is too thick.

[0102] Please see Figure 6 In some embodiments, the adhesive 50 has a first recess 50c and a second recess 50d. In the third direction Z, the projection of the first recess 50c onto the projection of the first tab 30 onto the projection of the first tab 40 onto the projection of the second tab 40 onto the projection of the first tab 40 onto the projection of the first tab 30 onto the projection of the first tab 40 onto the first tab 40. The provision of the first recess 50c and the second recess 50d reduces the total thickness of the electrode assembly 20 along the third direction Z at locations corresponding to the first tab 30 and the second tab 40, thus compensating for the increase in total thickness of the electrochemical device 100 at locations corresponding to the first tab 30 and the second tab 40 caused by the provision of the adhesive 50, which is beneficial for improving energy density. Both the first recess 50c and the second recess 50d penetrate one edge 500 of the adhesive 50 at the winding center O. In the thickness direction of the adhesive 50 (i.e., the stacking direction of the adhesive layer 50a and the metal layer 50b), the depths of the first recess 50c and the second recess 50d can be set according to the thicknesses of the first tab 30 and the second tab 40, respectively. For example, each of the first recess 50c and the second recess 50d can be formed on the adhesive layer 50a, or on the metal layer 50b, or simultaneously on both the adhesive layer 50a and the metal layer 50b.

[0103] The present application will be described in detail below with reference to specific embodiments. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0104] Example 1

[0105] like Figure 2 As shown, the adhesive 50 includes a first adhesive 51 and a second adhesive 52. The first adhesive 51 and the second adhesive 52 are spaced apart in the winding direction D. In this embodiment, the first adhesive 51 and the second adhesive 52 are respectively bonded to the surfaces of the first segment 2121 and the second segment 2123. Therefore, when viewed from the second direction Y, the first adhesive 51 and the second adhesive 52 are located on different sides of the winding center O. Furthermore, the first adhesive 51 is disposed on the surface of the first segment 2121 facing the winding center O, and the second adhesive 52 is disposed on the surface of the second segment 2123 facing the winding center O.

[0106] In this embodiment, the first current collector 210 is an aluminum foil, and the second current collector 220 is a copper foil. Since the aluminum foil itself has a low melting point, the adhesive 50 is bonded to the surface of the aluminum foil, which can reduce the risk that the aluminum foil will melt at the short circuit point first during needle punching. Therefore, the electrochemical device 100 has high safety and reliability during needle punching.

[0107] Example 2

[0108] like Figure 7 As shown, the adhesive 50 is disposed on the second region 2220. In this embodiment, the adhesive 50 includes a third adhesive 53 and a fourth adhesive 54. The third adhesive 53 and the fourth adhesive 54 are spaced apart in the winding direction D. The third adhesive 53 and the fourth adhesive 54 are respectively bonded to the surfaces of the third segment 2221 and the fourth segment 2223. Therefore, when viewed from the second direction Y, the third adhesive 53 and the fourth adhesive 54 are located on different sides of the winding center O. Furthermore, the third adhesive 53 is disposed on the surface of the third segment 2221 facing the winding center O, and the fourth adhesive 54 is disposed on the surface of the fourth segment 2223 facing the winding center O.

[0109] In this embodiment, the first current collector 210 is an aluminum foil, and the second current collector 220 is a copper foil. Compared to Embodiment 1, due to the higher hardness and mechanical strength of the copper foil itself, the bonding member 50 adheres to the surface of the copper foil, which significantly improves the mechanical strength of the vest structure. Therefore, when a heavy object impacts, the copper foil can maintain a larger contact area with the aluminum foil to conduct electricity, diverting the short-circuit current in the electrode assembly 20. Thus, the electrochemical device 100 has higher safety and reliability when a heavy object impacts.

[0110] Example 3

[0111] like Figure 8 As shown, the adhesive 50 is simultaneously disposed on the first region 2120 and the second region 2220. In this embodiment, the adhesive 50 includes a first adhesive 51 and a fourth adhesive 54. The first adhesive 51 and the fourth adhesive 54 are spaced apart in the winding direction D. The first adhesive 51 is bonded to the surface of the first segment 2121, and the fourth adhesive 54 is bonded to the surface of the fourth segment 2223. Therefore, when viewed from the second direction Y, the first adhesive 51 and the fourth adhesive 54 are located on different sides of the winding center O. Furthermore, the first adhesive 51 is disposed on the surface of the first segment 2121 facing the winding center O, and the fourth adhesive 54 is disposed on the surface of the fourth segment 2223 facing the winding center O.

[0112] In this embodiment, the first current collector 210 is an aluminum foil, and the second current collector 220 is a copper foil. Compared with Embodiments 1 and 2, since the adhesive 50 is respectively disposed on the copper foil and the aluminum foil, the electrochemical device 100 has higher safety and reliability in the event of needle puncture and heavy object impact.

[0113] Example 4

[0114] like Figure 9As shown, the adhesive 50 is simultaneously disposed on the first region 2120 and the second region 2220. In this embodiment, the adhesive 50 includes a second adhesive 52 and a third adhesive 53. The second adhesive 52 and the third adhesive 53 are spaced apart in the winding direction D. The second adhesive 52 is bonded to the surface of the second segment 2123, and the third adhesive 53 is bonded to the surface of the third segment 2221. Therefore, when viewed from the second direction Y, the second adhesive 52 and the third adhesive 53 are located on different sides of the winding center O. Furthermore, the second adhesive 52 is disposed on the surface of the second segment 2123 facing the winding center O, and the third adhesive 53 is disposed on the surface of the third segment 2221 facing the winding center O.

[0115] In this embodiment, the first current collector 210 is an aluminum foil, and the second current collector 220 is a copper foil. Compared with Embodiments 1 and 2, since the adhesive 50 is respectively disposed on the copper foil and the aluminum foil, the electrochemical device 100 can have higher safety and reliability in both needle penetration and heavy object impact.

[0116] Example 5

[0117] like Figure 10 As shown, the adhesive 50 is simultaneously disposed on the first region 2120 and the second region 2220. In this embodiment, the adhesive 50 includes a second adhesive 52 and a fourth adhesive 54. The second adhesive 52 and the fourth adhesive 54 are spaced apart in the winding direction D. The second adhesive 52 is bonded to the surface of the second segment 2123. The fourth adhesive 54 is bonded to the surface of the fourth segment 2223. Therefore, when viewed from the second direction Y, the second adhesive 52 and the fourth adhesive 54 are located on the same side of the winding center. Furthermore, the second adhesive 52 is disposed on the surface of the second segment 2123 facing the winding center O, and the fourth adhesive 54 is disposed on the surface of the fourth segment 2223 facing the winding center O.

[0118] In this embodiment, the first current collector 210 is an aluminum foil, and the second current collector 220 is a copper foil. Compared with Embodiments 3 and 4, when the electrochemical device 100 is subjected to a needle puncture or a heavy object impact, the adhesive 50 simultaneously improves the mechanical strength of the copper foil and aluminum foil at the same short circuit point, thus further reducing the risk of short circuit point melting and improving the safety and reliability of the electrochemical device 100.

[0119] Example 6

[0120] like Figure 11As shown, in this embodiment, the adhesive 50 includes a first adhesive 51, a second adhesive 52, a third adhesive 53, and a fourth adhesive 54. In the winding direction D, the first adhesive 51, the second adhesive 52, the third adhesive 53, and the fourth adhesive 54 are spaced apart. The first adhesive 51 and the second adhesive 52 are respectively bonded to the surfaces of the first segment 2121 and the second segment 2123. The third adhesive 53 and the fourth adhesive 54 are respectively bonded to the surfaces of the third segment 2221 and the fourth segment 2223. Therefore, when viewed from the second direction Y, the first adhesive 51 and the third adhesive 53 are located on one side of the winding center O, and the second adhesive 52 and the fourth adhesive 54 are located on the other side of the winding center O.

[0121] In this embodiment, the first current collector 210 is an aluminum foil, and the second current collector 220 is a copper foil. Compared to embodiment 5, when the foreign object completely passes through the electrode assembly 20, the adhesive 50 located on different sides of the winding center O increases the number of short-circuit points in the electrode assembly 20 that can cause a continuous short circuit. This facilitates faster shunting of the short-circuit current in the electrode assembly 20, thereby improving the safety and reliability of the electrochemical device 100.

[0122] Example 7

[0123] The difference from Example 6 is that, as Figure 12 As shown, the first adhesive member 51 and the second adhesive member 52 can be connected in the winding direction D. In this case, the adhesive member 50 may further include a fifth adhesive member 55. The fifth adhesive member 55 is disposed on the surface of at least one of the first bending segment 2122 and the second bending segment 2124, for connecting the first adhesive member 51 and the second adhesive member 52.

[0124] Furthermore, the third adhesive 53 and the fourth adhesive 54 can also be connected in the winding direction D. In this case, the adhesive 50 may further include a sixth adhesive 56. The sixth adhesive 56 is disposed on the surface of at least one of the third bending segment 2222 and the fourth bending segment 2224, for connecting the third adhesive 53 and the fourth adhesive 54. In this case, when the electrochemical device 100 is needled or struck by a heavy object along the first direction X, the first region 2120 and the second region 2220 can also short-circuit, and the risk of melting at the short-circuit point is reduced.

[0125] The electrochemical device 100 of this application includes all devices capable of undergoing electrochemical reactions. Specifically, the electrochemical device 100 includes all types of primary cells, secondary cells, fuel cells, solar cells, and capacitors (e.g., supercapacitors). Optionally, the electrochemical device 100 can be a secondary cell, including lithium metal secondary cells, lithium-ion secondary cells, lithium polymer secondary cells, lithium-ion polymer secondary cells, and sodium-ion batteries, etc.

[0126] Please see Figure 13 One embodiment of this application also provides an electronic device 1, including the electrochemical device 100 described above. The electronic device 1 of this application may be, but is not limited to, a laptop computer, a pen-based computer, a mobile computer, an e-book player, a portable telephone, a portable fax machine, a portable copier, a portable printer, a stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini CD-ROM, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, an electric bicycle, a bicycle, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large-capacity batteries, and lithium-ion capacitors, etc.

[0127] The performance of the electrochemical device 100 provided in this application will be described below with reference to the comparative examples and the above-described Examples 1-7.

[0128] Comparative Example

[0129] Similar to Example 1, except that the electrochemical device 100 does not have an adhesive element 50.

[0130] Then, 10 electrochemical devices from each of the examples and comparative examples were taken and subjected to needle penetration and impact tests, and the test results were recorded in Table 1.

[0131] The needle penetration test includes the following steps: 1) Full charging at 25±3℃ (constant current charging of electrochemical device 100 to 4.4V at 0.5C, then constant voltage charging of electrochemical device 100 to 0.05C at 4.4V); 2) Using a steel nail with a diameter of 4mm and made of carbon steel, needle penetration is performed from the front of electrochemical device 100 (i.e., the outer surface of the second section 2123) at room temperature (e.g., 25℃), with a needle penetration speed of 100mm / s and a needle penetration depth of 50% of the thickness of electrochemical device 100; 3) Observing whether electrochemical device 100 catches fire or explodes.

[0132] The impact test steps include: 1) Full charging at 25±3℃ (constant current charging of electrochemical device 100 at 0.5C to 4.4V, then constant voltage charging of electrochemical device 100 at 4.4V to 0.05C and then cutting off); 2) Placing electrochemical device 100 on the test platform and placing a 15.8mm diameter round rod vertically at the center of the front of electrochemical device 100; 3) Using a 9.1±0.1kg weight, dropping vertically from a height of 610±25mm into the intersection of the round rod and the front of electrochemical device 100; 4) Observing whether the battery catches fire or explodes.

[0133] Table 1

[0134] Impact test pass rate Needle prick test pass rate Comparative Example 2 / 10 3 / 10 Example 1 6 / 10 10 / 10 Example 2 10 / 10 6 / 10 Example 3 10 / 10 6 / 10 Example 4 8 / 10 10 / 10 Example 5 10 / 10 10 / 10 Example 6 10 / 10 10 / 10 Example 7 10 / 10 10 / 10

[0135] Note: The pass rate X / 10 means that out of 10 samples tested, X samples passed the test.

[0136] As shown in Table 1, compared to the comparative examples, Examples 1-7, due to the presence of adhesive members 50 on at least one of the first region 2120 and the second region 2220, exhibited higher pass rates in the needle penetration and heavy object impact tests, thus significantly improving the safety performance of the electrochemical device. Specifically, the experiments revealed that, compared to Examples 1 and 4, Examples 2-3 and 5-7, by providing adhesive members 50 on the second region 2220 (especially at the fourth segment 2223) on the front of the electrochemical device 100, achieved relatively higher pass rates in the heavy object impact test. Furthermore, compared to Examples 2-3, Examples 1 and 4-7, by providing adhesive members 50 on the first region 2120 (especially at the second segment 2123) on the front of the electrochemical device 100, achieved relatively higher pass rates in the needle penetration test.

[0137] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with this application are still within the scope of this application.

Claims

1. An electrochemical device comprising an electrode assembly, the electrode assembly being a wound structure, comprising a first electrode, a second electrode, and a separator disposed between the first electrode and the second electrode, the first electrode comprising a first current collector and a first active material layer disposed on the surface of the first current collector, the first current collector comprising a first empty foil region where the first active material layer is not disposed, the second electrode comprising a second current collector and a second active material layer disposed on the surface of the second current collector, the second current collector comprising a second empty foil region where the second active material layer is not disposed; The first empty foil region includes a first region located on the outermost layer of the first electrode sheet; the second empty foil region includes a second region located on the outermost layer of the second electrode sheet. wherein The electrochemical device further includes an adhesive component comprising a laminated adhesive layer and a metal layer, the adhesive layer comprising a conductive material, and the adhesive component bonding, through the adhesive layer, to the surface of at least one of the first region and the second region facing the winding center of the electrode assembly. Along the winding direction of the electrode assembly, the adhesive does not contact the first active material layer.

2. The electrochemical device of claim 1, wherein, Along the winding direction of the electrode assembly, the first region includes a first segment, a first bent segment, a second segment, and a second bent segment connected in sequence, and the adhesive is disposed on the surfaces of the first segment and the second segment.

3. The electrochemical device of claim 2, wherein, The adhesive is also disposed on the surface of at least one of the first bending segment and the second bending segment.

4. The electrochemical device of claim 1 or 2, wherein, Along the winding direction of the electrode assembly, the second region includes a third bend segment, a third segment, a fourth bend segment, and a fourth segment connected in sequence, with the adhesive disposed on the surfaces of the third segment and the fourth segment.

5. The electrochemical device of claim 4, wherein, The adhesive is also disposed on the surface of at least one of the third and fourth bends.

6. The electrochemical device of claim 1, wherein, Along the winding direction of the electrode assembly, the adhesive disposed in the first region and the adhesive disposed in the second region are located on different sides of the winding center of the electrode assembly.

7. The electrochemical device of claim 1, wherein, Along the winding direction of the electrode assembly, the adhesive disposed in the first region and the adhesive disposed in the second region are respectively located on the same side of the winding center of the electrode assembly.

8. The electrochemical device as claimed in claim 1, wherein, The electrode assembly further includes a first electrode tab and a second electrode tab, wherein the first electrode tab is electrically connected to the first current collector and the second electrode tab is electrically connected to the second current collector; The adhesive has a first recess and a second recess. In the thickness direction of the electrode assembly, the projection of the first recess in the first region covers the projection of the first tab in the first region, and the projection of the second recess in the first region covers the projection of the second tab in the first region.

9. The electrochemical device as claimed in claim 1, wherein, The adhesive layer includes at least one of conductive silver paste or conductive silicone, and / or the metal layer includes at least one of copper, aluminum, titanium or nickel.

10. The electrochemical device as claimed in claim 1, wherein, The thickness of the adhesive layer is 4 micrometers to 10 micrometers, and / or the thickness of the metal layer is 4 micrometers to 20 micrometers.

11. The electrochemical device as claimed in claim 1, wherein, The first region is located at the outermost edge of the electrode assembly, and the second region is located at the second outermost edge of the electrode assembly.

12. An electronic device, wherein, Includes the electrochemical device as described in any one of claims 1 to 11.

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