Electrochemical devices and electronic devices

Abstract

The present application provides an electrochemical device and an electronic device, wherein the electrochemical device comprises a packaging shell, an electrode assembly contained in the packaging shell, and adhesive tape, wherein the electrode assembly comprises a pole piece, the pole piece comprises a current collector, the adhesive tape comprises a substrate layer and a first adhesive layer, the first adhesive layer comprises a first surface and a second surface opposite to the first surface, the first surface is adhered to a surface of the substrate layer, the second surface is adhered to the inner surface of the electrode assembly or the packaging shell, the tensile strength of the substrate layer is σ1, the tensile strength σ2 of the current collector is 150MPa to 500MPa, and 2σ2≤σ1≤1500MPa is satisfied. By regulating the tensile strength relationship between the substrate layer and the current collector, the safety performance of the electrochemical device can be effectively improved.

Description

Technical Field

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

[0002] Lithium-ion batteries have the advantages of high energy storage density, high open circuit voltage, low self-discharge rate, long cycle life, and good safety, and are widely used in various fields such as portable power storage, electronic equipment, and electric vehicles. However, higher requirements are also placed on the comprehensive performance of lithium-ion batteries, especially the safety performance of lithium-ion batteries.

[0003] When a lithium-ion battery is subjected to a large external force, the structure of the internal electrode assembly of the lithium-ion battery will be destroyed, which may lead to the breakage of the positive electrode sheet, the negative electrode sheet, the positive electrode material layer, the negative electrode material layer, and the tearing of the isolation membrane, causing a short circuit inside the lithium-ion battery. The heat generated by the internal short circuit of the lithium-ion battery can easily cause the lithium-ion battery to run away, especially for high-energy-density lithium-ion batteries and fast-charging lithium-ion batteries, whose electrochemical thermal runaway is more severe, and may even cause safety accidents such as fire and explosion. Therefore, improving the structural strength of lithium-ion batteries to improve the safety performance of lithium-ion batteries has become an urgent problem to be solved. Summary of the invention

[0004] The purpose of the present application is to provide an electrochemical device and an electronic device to improve the safety performance of the electrochemical device.

[0005] The first aspect of the present application provides an electrochemical device, including a packaging shell, an electrode assembly contained in the packaging shell, and adhesive tape, wherein the electrode assembly includes an electrode sheet, the electrode sheet includes a current collector, the adhesive tape includes a substrate layer and a first adhesive layer, the first adhesive layer includes a first surface and a second surface opposite to the first surface, the first surface is adhered to one surface of the substrate layer, the second surface is adhered to the inner surface of the electrode assembly or the packaging shell, and the tensile strength of the substrate layer is σ 1 , the tensile strength of the current collector σ 2 150MPa to 500MPa, satisfying 2σ 2 ≤σ 1 ≤1500MPa. By adjusting the tensile strength relationship between the substrate layer and the current collector within the above range, the mechanical strength of the electrochemical device against compression can be improved, thereby improving the safety performance of the electrochemical device.

[0006] In some embodiments of the present application, the second surface is adhered to the outermost layer of the electrode assembly, which is beneficial to improving the mechanical strength of the electrode assembly against compression, thereby improving the safety performance of the electrochemical device.

[0007] In some embodiments of the present application, the second surface is adhered to the inner surface of the packaging shell close to the electrode assembly, which is beneficial to improving the mechanical strength of the electrochemical device against extrusion, thereby improving the safety performance of the electrochemical device.

[0008] In some embodiments of the present application, the electrode assembly includes a pole ear, the pole ear is electrically connected to a surface of a pole piece, the pole piece includes a connection portion where the pole ear is connected to the pole piece, and the electrochemical device satisfies at least one of the following features: (i) the first adhesive layer covers the connection portion; (ii) the first adhesive layer covers the connection portion, and the first adhesive layer is attached to another surface of the pole piece and the attachment position is opposite to the connection portion; (iii) the first adhesive layer is attached to another pole piece with opposite polarity to the pole piece and the attachment position is opposite to the connection portion. The electrochemical device satisfies at least one of features (i) to (iii), and can improve the influence of burrs generated when connecting the pole ear on the safety performance of the electrode assembly, thereby improving the safety performance of the electrochemical device.

[0009] In some embodiments of the present application, the electrode assembly includes a pole ear, the pole piece is provided with a groove, the pole ear is arranged in the groove, the first adhesive layer covers the groove, or the first adhesive layer is adhered to another pole piece with opposite polarity to the pole piece and the adhesion position is opposite to the groove position. It can improve the safety performance of the electrochemical device

[0010] In some embodiments of the present application, the electrode assembly is a winding structure, the adhesive tape is arranged between the outer surface of the secondary outer ring of the electrode assembly and the inner surface of the outermost ring of the electrode assembly, and the second surface of the first adhesive layer is attached to the outer surface of the secondary outer ring of the electrode assembly or the inner surface of the outermost ring of the electrode assembly. Thus, the electrode assembly is not easily deformed under the action of external force, the structural stability of the electrode assembly is improved, and thus it is beneficial to improve the safety performance of the electrochemical device.

[0011] In some embodiments of the present application, the material of the substrate layer includes at least one of metal, non-metal, polymer material, and composite material. By selecting the above materials, it is beneficial to obtain a tape with good mechanical properties, thereby improving the safety performance of the electrochemical device.

[0012] In some embodiments of the present application, the thickness D of the adhesive tape 1 20μm to 200μm, the thickness of the substrate layer is 0.4D 1 To 0.9D 1 , the thickness of the first adhesive layer is 0.1D 1 Up to 0.6D 1 By adjusting the thickness of the adhesive tape, the substrate layer and the first adhesive layer within the above range, it is beneficial to obtain an adhesive tape with good mechanical properties, thereby improving the safety performance of the electrochemical device and maintaining a high energy density of the electrochemical device.

[0013] In some embodiments of the present application, a second adhesive layer is provided on the other surface of the substrate layer, and when the second surface is attached to the electrode assembly, the surface of the second adhesive layer facing away from the substrate layer is attached to the inner surface of the packaging shell; or, when the second surface is attached to the inner surface of the packaging shell, the surface of the second adhesive layer facing away from the substrate layer is attached to the electrode assembly. Thus, under the action of external force, the electrode assembly is not easily displaced in the packaging shell, which improves the stability of the overall structure of the electrochemical device, thereby facilitating the improvement of the safety performance of the electrochemical device.

[0014] In some embodiments of the present application, a second adhesive layer is provided on the other surface of the substrate layer, the electrode assembly includes a pole ear, the pole ear is electrically connected to a surface of the pole piece, the pole piece includes a connection area where the pole ear is connected to the pole piece, and the electrochemical device satisfies at least one of the following features: (iv) the adhesive tape covers the connection area; (v) the adhesive tape covers the connection area, and the adhesive tape is pasted on the other surface of the pole piece and the pasting position is opposite to the connection area; (vi) the adhesive tape is pasted on another pole piece with opposite polarity to the pole piece and the pasting position is opposite to the connection area. The electrochemical device satisfies at least one of the features (iv) to (vi), which can improve the influence of the burrs generated when connecting the pole ear on the safety performance of the electrode assembly, thereby improving the safety performance of the electrochemical device.

[0015] In some embodiments of the present application, the thickness D of the adhesive tape 2 30μm to 320μm, the thickness of the substrate layer is 0.24D 2 To 0.82D 2 , the thickness of the first adhesive layer is 0.09D 2 To 0.38D 2 , the thickness of the second adhesive layer is 0.09D 2 To 0.38D 2 By adjusting the thickness of the adhesive tape, the first adhesive layer of the substrate layer and the second adhesive layer within the above range, it is beneficial to obtain an adhesive tape with good mechanical properties, thereby improving the safety performance of the electrochemical device and maintaining a high energy density of the electrochemical device.

[0016] In some embodiments of the present application, the softening point of the second adhesive layer is lower than the softening point of the first adhesive layer, which is beneficial to improving the safety performance of the electrochemical device at high temperatures.

[0017] The second aspect of the present application provides an electronic device, which includes the electrochemical device in any of the above embodiments. The electrochemical device provided by the present application has good safety performance, so the electronic device provided by the present application also has good safety performance.

[0018] The present application provides an electrochemical device and an electronic device, wherein the electrochemical device comprises a packaging shell, an electrode assembly contained in the packaging shell, and adhesive tape, wherein the electrode assembly comprises an electrode sheet, the electrode sheet comprises a current collector, the adhesive tape comprises a substrate layer and a first adhesive layer, the first adhesive layer comprises a first surface and a second surface opposite to the first surface, the first surface is adhered to one surface of the substrate layer, the second surface is adhered to the inner surface of the electrode assembly or the packaging shell, and the tensile strength of the substrate layer is σ 1 , the tensile strength of the current collector σ 2 150MPa to 500MPa, satisfying 2σ 2 ≤σ 1 ≤1500MPa. By adjusting the tensile strength relationship between the substrate layer and the current collector within the above range, the safety performance of the electrochemical device can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the implementation scheme of the present application or the technical scheme in the prior art, the drawings required for use in the implementation scheme or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation schemes of the present application. For ordinary technicians in this field, other implementation schemes can also be obtained based on these drawings.

[0020] Figure 1 A schematic diagram of a cross-sectional structure along the thickness direction of an electrochemical device in some embodiments of the present application;

[0021] Figure 2 for Figure 1 A partial enlarged view of the middle A;

[0022] Figure 3 Schematic diagram of the cross-sectional structure along the thickness direction of the electrochemical device in other embodiments of the present application;

[0023] Figure 4 Schematic diagram of the cross-sectional structure along the thickness direction of the electrochemical device in other embodiments of the present application;

[0024] Figure 5 Schematic diagram of the cross-sectional structure along the thickness direction of the electrochemical device in other embodiments of the present application;

[0025] Figure 6 for Figure 5 A partial enlarged view of point B in the middle;

[0026] Figure 7 for Figure 5 A schematic diagram of a negative electrode sheet containing a negative electrode tab of an electrochemical device;

[0027] Figure 8 A partial enlarged view of an electrochemical device in some other embodiments of the present application;

[0028] Fig. 9 A partial enlarged view of an electrochemical device in some other embodiments of the present application;

[0029] Fig.10 A schematic diagram of the cross-sectional structure of a positive electrode sheet of an electrochemical device along the thickness direction in some embodiments of the present application;

[0030] Fig.11 Schematic diagram of the cross-sectional structure along the thickness direction of the electrochemical device in other embodiments of the present application;

[0031] Fig.12 Schematic diagram of the cross-sectional structure along the thickness direction of the electrochemical device in other embodiments of the present application;

[0032] Fig.13 Schematic diagram of the cross-sectional structure along the thickness direction of the electrochemical device in other embodiments of the present application;

[0033] Fig.14 Schematic diagram of the cross-sectional structure along the thickness direction of the electrochemical device in other embodiments of the present application;

[0034] Fig.15 for Fig.14 A partial enlarged view of point C in the middle;

[0035] Fig.16 It is a partial enlarged view of the electrochemical device in some embodiments of the present application. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme, and advantages of the present application more clearly understood, the present application is further described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other technical schemes obtained by ordinary technicians in the field belong to the scope of protection of the present application.

[0037] It should be noted that in the specific embodiments of the present application, a lithium-ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to a lithium-ion battery.

[0038] The first aspect of the present application provides an electrochemical device, including a packaging shell, an electrode assembly contained in the packaging shell, and adhesive tape, wherein the electrode assembly includes an electrode sheet, the electrode sheet includes a current collector, the adhesive tape includes a substrate layer and a first adhesive layer, the first adhesive layer includes a first surface and a second surface opposite to the first surface, the first surface is adhered to one surface of the substrate layer, the second surface is adhered to the inner surface of the electrode assembly or the packaging shell, and the tensile strength of the substrate layer is σ 1 , the tensile strength of the current collector σ2 150MPa to 500MPa, satisfying 2σ 2 ≤σ 1 ≤1500MPa. For example, the tensile strength of the current collector σ 2 It may be 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, 500 MPa or any range therebetween and satisfy 2σ 2 ≤σ 1 ; The tensile strength of the substrate layer is σ 1 It may be 300 MPa, 400 MPa, 500 MPa, 600 MPa, 800 MPa, 1000 MPa, 1100 MPa, 12000 MPa, 1300 MPa, 1400 MPa, 1500 MPa or any range therebetween and satisfy 2σ 2 ≤σ 1 Without being limited to any theory, the inventors of the present application have found that when σ 1 Less than 2σ 2 When the electrochemical device is subjected to external force, the adhesive tape is easily damaged. By adjusting the tensile strength σ of the current collector 2 is 150MPa to 500MPa and the tensile strength of the substrate layer is σ 1 Satisfy 2σ 2 ≤σ 1 ≤1500MPa, so that the adhesive tape and the electrode sheet form a synergistic effect, which can improve the mechanical strength of the electrochemical device against extrusion, thereby improving the safety performance of the electrochemical device. In the present application, the electrode sheet can be a positive electrode sheet or a negative electrode sheet. When the electrode sheet is a positive electrode sheet, the positive electrode sheet includes a positive electrode current collector; when the electrode sheet is a negative electrode sheet, the negative electrode sheet includes a negative electrode current collector.

[0039] In some embodiments of the present application, the second surface is attached to the outermost layer of the electrode assembly. It is beneficial to improve the mechanical strength of the electrode assembly to resist extrusion, thereby improving the safety performance of the electrochemical device. In the present application, the outermost layer of the electrode assembly refers to the surface close to the packaging shell. The outermost layer of the electrode assembly can be a positive electrode sheet, a negative electrode sheet, or a separator. Among them, when the outermost layer of the electrode assembly is a positive electrode sheet, the positive electrode sheet may include a positive electrode material layer arranged on the surface of the positive electrode collector, the active material in the positive electrode material layer includes a positive electrode active material, and the second surface of the first glue layer is attached to the positive electrode material layer; or, the positive electrode collector surface of the outermost layer of the electrode assembly may include a first blank area not coated with a positive electrode material layer, and the second surface of the first glue layer is attached to the positive electrode material layer and / or the first blank area. When the outermost layer of the electrode assembly is a negative electrode sheet, the negative electrode sheet may include a negative electrode material layer disposed on the surface of the negative electrode current collector, the active material in the negative electrode material layer includes a negative electrode active material, and the second surface of the first adhesive layer is attached to the negative electrode material layer; or, the surface of the negative electrode current collector of the outermost layer of the electrode assembly may include a second blank area not coated with the negative electrode material layer, and the second surface of the first adhesive layer is attached to the negative electrode material layer and / or the second blank area. The surface of the positive electrode current collector refers to the surface along the thickness direction of the positive electrode current collector itself, and the surface of the negative electrode current collector refers to the surface along the thickness direction of the negative electrode current collector itself.

[0040] The adhesive tape may be attached to one side of the electrode assembly along the thickness direction, or may be attached to two opposite sides of the electrode assembly along the thickness direction. Figure 1 and Figure 2As shown, the electrochemical device includes a packaging shell 10, an electrode assembly 20 contained in the packaging shell 10, and a glue tape 30. The glue tape 30 is pasted on one side of the electrode assembly 20 along the thickness direction of the electrode assembly 20. The electrode assembly 20 includes a positive electrode sheet 21, a negative electrode sheet 22, and a separator 23 located between the positive electrode sheet 21 and the negative electrode sheet 22. The positive electrode sheet 21 includes a positive electrode collector 211, and the negative electrode sheet includes a negative electrode collector 221. The glue tape 30 includes a substrate layer 31 and a first glue layer 32. The outermost electrode sheet of the electrode assembly 20 is the positive electrode sheet 21. At the end of the electrode assembly 20, the surface of the positive electrode sheet 21 close to the packaging shell 10 has a first blank area 222 on which no active material is coated. The second surface of the first glue layer 32 is pasted on the first blank area 222, that is, the second surface of the first glue layer 32 is directly pasted on the positive electrode collector 211. In this way, it is beneficial to improve the mechanical strength of the electrode assembly against extrusion, thereby improving the safety performance of the electrochemical device. It is understandable that the outermost electrode sheet of the electrode assembly can also be a negative electrode sheet. At the end of the electrode assembly, the negative electrode sheet has a second blank area on the side close to the inner surface of the packaging shell that is not coated with active material. The second surface of the first adhesive layer is adhered to the second blank area, so that the second surface of the first adhesive layer is directly adhered to the negative electrode current collector. Adhesive tape can be pasted on both sides of the electrode assembly in the thickness direction and the width direction, and the adhesive tape pasting position can be selected according to actual conditions. For example, Figure 3 As shown, along the thickness direction of the electrode assembly 20, adhesive tape 30 is pasted on both sides of the electrode assembly 20, and the first adhesive layer 32 is pasted on the first blank area 222. In this way, the safety performance of the electrochemical device can be further improved.

[0041] In some embodiments of the present application, illustratively, Figure 4 As shown, the second surface of the first adhesive layer 32 of the adhesive tape 30 is pasted on the inner surface of the packaging shell 10 near the electrode assembly 20. In this way, it is beneficial to improve the mechanical strength of the electrochemical device against extrusion, thereby improving the safety performance of the electrochemical device. It is understandable that the adhesive tape can be pasted on any surface of the packaging shell near the electrode assembly, and the pasting position of the adhesive tape can be selected according to actual conditions. The adhesive tape can also be pasted on the electrode assembly and the surface of the packaging shell near the electrode assembly at the same time, and the pasting position of the adhesive tape can be selected according to actual conditions.

[0042] In some embodiments of the present application, the electrode assembly includes a pole ear, the pole ear is electrically connected to a surface of a pole piece, the pole piece includes a connection portion where the pole ear is connected to the pole piece, and the electrochemical device satisfies at least one of the following features: (i) the first adhesive layer covers the connection portion; (ii) the first adhesive layer covers the connection portion, and the first adhesive layer is attached to another surface of the pole piece and the attachment position is opposite to the connection portion; (iii) the first adhesive layer is attached to another pole piece with opposite polarity to the pole piece and the attachment position is opposite to the connection portion. The electrochemical device satisfies at least one of features (i) to (iii), and can improve the influence of burrs generated when connecting the pole ear on the safety performance of the electrode assembly, thereby improving the safety performance of the electrochemical device.

[0043] For example, Figures 5 to 7 As shown, the electrode assembly 20 includes a positive electrode tab 24 and a negative electrode tab 25, the positive electrode tab 24 is electrically connected to the positive electrode sheet 21, and the negative electrode tab 25 is electrically connected to the negative electrode sheet 22. The first adhesive layer 32 of the adhesive tape 30 covers the connecting portion 223 between the negative electrode tab 25 and the negative electrode sheet 22. In this way, the setting of the adhesive tape can improve the influence of the burrs generated when connecting the tabs on the safety performance of the electrode assembly, thereby improving the safety performance of the electrochemical device. It is understandable that the adhesive tape can also cover and paste the connecting portion between the positive electrode tab and the positive electrode sheet, or the adhesive tape simultaneously covers and pastes the connecting portion between the positive electrode tab and the positive electrode sheet and the connecting portion between the negative electrode tab and the negative electrode sheet.

[0044] In some embodiments of the present application, the first adhesive layer covers the connection portion, and the first adhesive layer is also pasted on the other surface of the electrode piece and the pasting position is opposite to the connection portion. In this way, the setting of the adhesive tape can improve the influence of the burrs generated on both sides of the electrode piece when connecting the electrode lugs on the safety performance of the electrode assembly, thereby improving the safety performance of the electrochemical device. For example, Figure 7 and Figure 8 As shown, the negative electrode tab 25 is connected to one surface of the negative electrode current collector 221, the first adhesive layer 32 of the adhesive tape 30 is pasted on the connection portion 223 between the negative electrode tab 25 and the negative electrode sheet 22, and the first adhesive layer 32 of the adhesive tape 30 is pasted on the other surface of the negative electrode sheet 22 and the pasting position is opposite to the connection portion 223. It can be understood that the adhesive tape can also be pasted on the connection portion between the positive electrode tab and the positive electrode sheet, and the surface of the positive electrode sheet not connected to the tab and the pasting position is opposite to the connection portion.

[0045] For example, Fig. 9As shown, the first adhesive layer 32 of the adhesive tape 30 is pasted on the positive electrode sheet 21 and the pasting position is opposite to the connection part 223 of the negative electrode tab 25 and the negative electrode sheet 22. In this way, the setting of the adhesive tape can also improve the influence of the burrs generated when connecting the tabs on the safety performance of the electrode assembly. It is understandable that the adhesive tape can also be set on the negative electrode sheet, and the pasting position is opposite to the connection part of the positive electrode tab and the positive electrode sheet.

[0046] In some embodiments of the present application, the electrode assembly includes a pole ear, the pole piece is provided with a groove, the pole ear is arranged in the groove, the first adhesive layer covers the groove, or the first adhesive layer is adhered to another pole piece with opposite polarity to the pole piece and the adhesion position is opposite to the groove position. Fig.10 As shown, the positive electrode plate 21 is provided with a groove 212, and the positive electrode ear 24 is arranged in the groove 212. The first adhesive layer of the adhesive paper is covered on the groove. The connection reliability between the positive electrode ear and the positive electrode plate can be improved, which is beneficial to improving the safety performance of the electrochemical device. Alternatively, the first adhesive layer of the adhesive paper is pasted on the negative electrode plate, and the setting position of the adhesive paper is opposite to the position of the groove. It can be understood that the negative electrode plate can also be provided with a groove, the negative electrode ear is arranged in the groove, and the adhesive paper covers the groove. Alternatively, the first adhesive layer of the adhesive paper is pasted on the positive electrode plate, and the setting position of the adhesive paper is opposite to the position of the groove.

[0047] In some embodiments of the present application, the electrode assembly is a winding structure, the adhesive tape is arranged between the outer surface of the secondary outer ring of the electrode assembly and the inner surface of the outermost ring of the electrode assembly, and the second surface of the first adhesive layer is adhered to the outer surface of the secondary outer ring of the electrode assembly or the inner surface of the outermost ring of the electrode assembly. Thus, the electrode assembly is not easily deformed under the action of external force, which improves the structural stability of the electrode assembly, thereby facilitating the improvement of the safety performance of the electrochemical device. For example, Fig.11 As shown, the outermost layer of the electrode assembly 20 is the positive electrode sheet 21, and the adhesive tape 30 is arranged between the positive electrode sheet 21 of the second outer circle of the electrode assembly 20 and the positive electrode sheet 21 of the outermost circle of the electrode assembly 20, and the second surface of the first adhesive layer 32 of the adhesive tape 30 is pasted on the inner surface of the outermost circle positive electrode sheet 21 of the electrode assembly 20 away from the packaging shell 10. Alternatively, the second surface of the first adhesive layer of the adhesive tape is pasted on the outer surface of the second outer circle positive electrode sheet of the electrode assembly close to the packaging shell. It can be understood that when the outermost layer of the electrode assembly is the negative electrode sheet, the adhesive tape can also be arranged in the same way.

[0048] In some embodiments of the present application, the material of the substrate layer includes at least one of metal, non-metal, polymer material, and composite material. Preferably, the material of the substrate layer includes at least one of copper, aluminum, nickel, titanium, mica sheet, stainless steel, aluminum alloy, titanium alloy, and magnesium alloy. By selecting the above materials, it is beneficial to obtain a tape with good mechanical properties, thereby improving the safety performance of the electrochemical device.

[0049] In some embodiments of the present application, the thickness D of the adhesive tape 1 20μm to 200μm, the thickness of the substrate layer is 0.4D 1 To 0.9D 1 , the thickness of the first adhesive layer is 0.1D 1 Up to 0.6D 1 For example, the thickness of the adhesive tape is D 1 It can be 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm or any range therebetween; the thickness of the substrate layer is 0.4D 1 , 0.5D 1 , 0.6D 1 , 0.7D 1 , 0.8D 1 , 0.9D 1 Or any range therebetween; the thickness of the first adhesive layer can be 0.1D 1 , 0.2D 1 , 0.3D 1 , 0.4D 1 , 0.5D 1 , 0.6D 1 Or any range therebetween. Without being limited to any theory, the inventors of the present application have found that by adjusting the thickness of the adhesive tape, the substrate layer and the first adhesive layer within the above range, it is beneficial to obtain an adhesive tape with good mechanical properties, thereby improving the safety performance of the electrochemical device and maintaining a higher energy density of the electrochemical device.

[0050] In some embodiments of the present application, a second adhesive layer is provided on the other surface of the substrate layer, and when the second surface is attached to the electrode assembly, the surface of the second adhesive layer facing away from the substrate layer is attached to the inner surface of the packaging shell; or, when the second surface is attached to the inner surface of the packaging shell, the surface of the second adhesive layer facing away from the substrate layer is attached to the electrode assembly. Thus, under the action of external force, the electrode assembly is not easily displaced in the packaging shell, which improves the stability of the overall structure of the electrochemical device, thereby facilitating the improvement of the safety performance of the electrochemical device.

[0051] For example, Fig.12 As shown, the other surface of the substrate layer 31 is provided with a second adhesive layer 33. When the second surface of the first adhesive layer 32 is adhered to the electrode assembly 20, the surface of the second adhesive layer 33 facing away from the substrate layer 31 is adhered to the inner surface of the packaging shell 10 near the electrode assembly 20. Therefore, under the action of external force, the electrode assembly is not easy to be displaced in the packaging shell, which improves the stability of the overall structure of the electrochemical device, thereby helping to improve the safety performance of the electrochemical device. Adhesive tape can be pasted on both sides of the electrode assembly in the thickness direction and the width direction, and the pasting position of the adhesive tape can be selected according to actual conditions. For example, Fig.13 As shown, along the thickness direction of the electrode assembly 20, adhesive tape 30 is pasted on both sides of the electrode assembly 20, the second surface of the first adhesive layer 32 is pasted on the electrode assembly 20, and the surface of the second adhesive layer 33 facing away from the substrate layer 31 is pasted on the inner surface of the packaging shell 10 close to the electrode assembly 20. In this way, the safety performance of the electrochemical device can be further improved. It is understandable that the second surface of the first adhesive layer can also be pasted on the inner surface of the packaging shell close to the electrode assembly, and the surface of the second adhesive layer facing away from the substrate layer is pasted on the electrode assembly.

[0052] In some embodiments of the present application, a second adhesive layer is provided on the other surface of the substrate layer, the electrode assembly includes a pole ear, the pole ear is electrically connected to a surface of the pole piece, the pole piece includes a connection area where the pole ear is connected to the pole piece, and the electrochemical device satisfies at least one of the following features: (iv) the adhesive tape covers the connection area; (v) the adhesive tape covers the connection area, and the adhesive tape is pasted on the other surface of the pole piece and the pasting position is opposite to the connection area; (vi) the adhesive tape is pasted on another pole piece with opposite polarity to the pole piece and the pasting position is opposite to the connection area. The electrochemical device satisfies at least one of the features (iv) to (vi), which can improve the influence of the burrs generated when connecting the pole ear on the safety performance of the electrode assembly, thereby improving the safety performance of the electrochemical device.

[0053] For example, Fig.14 and Fig.15 As shown, the electrode assembly 20 includes a positive electrode tab 24 and a negative electrode tab 25, the positive electrode tab 24 is electrically connected to the positive electrode sheet 21, and the negative electrode tab 25 is electrically connected to the negative electrode sheet 22. The first adhesive layer 32 of the adhesive tape 30 covers the connection area between the negative electrode tab 25 and the negative electrode sheet 22, and the second adhesive layer 33 of the adhesive tape 30 is pasted on the isolation film 23 adjacent to the negative electrode sheet 22 and the pasting position is opposite to the connection area. Alternatively, the second adhesive layer of the adhesive tape covers the connection area between the negative electrode tab and the negative electrode sheet, and the first adhesive layer of the adhesive tape is pasted on the isolation film adjacent to the negative electrode sheet and the pasting position is opposite to the connection area. In this way, the setting of the adhesive tape can improve the influence of the burrs generated when connecting the tabs on the safety performance of the electrode assembly, thereby improving the safety performance of the electrochemical device. It is understandable that the first adhesive layer of the adhesive tape can also cover and paste on the connection area between the positive electrode tab and the positive electrode sheet, and the second adhesive layer of the adhesive tape can be pasted on the separator adjacent to the positive electrode sheet and the pasting position is opposite to the connection area; or, the adhesive tape can be pasted on the connection area between the positive electrode tab and the positive electrode sheet and the connection area between the negative electrode tab and the negative electrode sheet at the same time. Among them, the pasting positions of the first adhesive layer and the second adhesive layer can be selected according to actual conditions.

[0054] In some embodiments of the present application, the adhesive tape covers the connection area, and the adhesive tape is pasted on the other surface of the electrode sheet that is not connected to the electrode ear and the pasting position is opposite to the connection area. In this way, the setting of the adhesive tape can improve the impact of burrs generated on both sides of the electrode sheet when connecting the electrode ear on the safety performance of the electrode assembly, thereby improving the safety performance of the electrochemical device. For example, Fig.16 As shown, the negative electrode tab 25 is connected to one surface of the negative electrode current collector 221, the first adhesive layer 32 of the adhesive tape 30 is pasted on the connection area between the negative electrode tab 25 and the negative electrode sheet 22, and the second adhesive layer 33 of the adhesive tape 30 is pasted on the separator 23 adjacent to one surface of the negative electrode sheet 22 and the pasting position is opposite to the connection area; and the first adhesive layer 32 of the adhesive tape 30 is pasted on the other surface of the negative electrode sheet 22 and the pasting position is opposite to the connection area, and the second adhesive layer 33 of the adhesive tape 30 is pasted on the separator 23 adjacent to the other surface of the negative electrode sheet 22 and the pasting position is opposite to the connection area. It can be understood that the adhesive tape can also be pasted on the connection area between the positive electrode tab and the positive electrode sheet, and the surface of the positive electrode sheet not connected to the tab and the pasting position is opposite to the connection area. The pasting positions of the first adhesive layer and the second adhesive layer can be selected according to actual conditions.

[0055] In some embodiments of the present application, the adhesive tape is pasted on another electrode sheet with opposite polarity and the pasting position is opposite to the connection area. Exemplarily, in some embodiments of the present application, the area where the negative electrode sheet is connected to the negative electrode ear is the connection area, the first adhesive layer of the adhesive tape is pasted on the positive electrode sheet and the pasting position is opposite to the connection area, the second adhesive layer of the adhesive tape is pasted on the isolation film, and the isolation film is located between the positive electrode sheet pasted with the first adhesive layer and the negative electrode sheet with the connection area. Alternatively, the area where the positive electrode sheet is connected to the positive electrode ear is the connection area, the first adhesive layer of the adhesive tape is pasted on the negative electrode sheet and the pasting position is opposite to the connection area, the second adhesive layer of the adhesive tape is pasted on the isolation film, and the isolation film is located between the positive electrode sheet with the connection area and the negative electrode sheet pasted with the first adhesive layer.

[0056] In some embodiments of the present application, the thickness D of the adhesive tape 2 30μm to 320μm, the thickness of the substrate layer is 0.24D 2 To 0.82D 2 , the thickness of the first adhesive layer is 0.09D 2 To 0.38D 2 , the thickness of the second adhesive layer is 0.09D 2 To 0.38D 2 For example, the thickness of the adhesive tape is D 1 It can be 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm or any range therebetween; the thickness of the substrate layer is 0.24D1 , 0.25D 1 , 0.3D 1 , 0.4D 1 , 0.5D 1 , 0.6D 1 , 0.7D 1 , 0.8D 1 , 0.82D 1 Or any range therebetween; the thickness of the first adhesive layer can be 0.09D 1 , 0.1D 1 , 0.2D 1 , 0.3D 1 , 0.38D 1 Or any range therebetween. Without being limited to any theory, the inventors of the present application have found that by regulating the thickness of the adhesive tape, the first adhesive layer of the substrate layer, and the second adhesive layer within the above range, it is beneficial to obtain an adhesive tape with good mechanical properties, thereby improving the safety performance of the electrochemical device and maintaining a higher energy density of the electrochemical device.

[0057] In some embodiments of the present application, the softening point of the second adhesive layer is lower than the softening point of the first adhesive layer. At room temperature, the second adhesive layer is not sticky. When the temperature of the electrochemical device increases, for example, when the temperature is greater than 70°C, the second adhesive layer becomes sticky, thereby facilitating the improvement of the safety performance of the electrochemical device at high temperatures.

[0058] The present application has no particular restrictions on the preparation method of the adhesive tape, as long as the purpose of the present application can be achieved. For example, the preparation method of the adhesive tape may include but is not limited to the following steps: dissolving the substance used in the first adhesive layer in a solvent to obtain a slurry of the first adhesive layer, dissolving the substance used in the second adhesive layer in a solvent to obtain a slurry of the second adhesive layer. Then, the slurry of the first adhesive layer is coated on one surface of the substrate layer along its own thickness direction, and adhesive tape I is obtained after drying, or the slurry of the first adhesive layer and the slurry of the second adhesive layer are respectively coated on two surfaces of the substrate layer along its own thickness direction, and adhesive tape II is obtained after drying.

[0059] The present application has no particular limitation on the materials in the first adhesive layer and the second adhesive layer, as long as the purpose of the present application can be achieved. For example, the first adhesive layer and the second adhesive layer independently include, but are not limited to, at least one of polyolefins, ethylene and its copolymers, polyesters, polyamides, polyurethanes, rubbers or acrylics.

[0060] The present application has no particular limitation on the solvent used in preparing the slurry of the first adhesive layer or the slurry of the second adhesive layer, as long as the purpose of the present application can be achieved. For example, the solvent may include but is not limited to at least one of water, toluene or xylene.

[0061] In the present application, there is no special restriction on the positive electrode current collector, as long as the purpose of the present application can be achieved, for example, it may include but is not limited to aluminum foil, aluminum alloy foil or composite current collector, etc. In the present application, there is no special restriction on the thickness of the positive electrode current collector, as long as the purpose of the present application can be achieved, for example, the thickness is 8μm to 12μm. In the present application, the positive electrode material layer can be arranged on one surface in the thickness direction of the positive electrode current collector, or on two surfaces in the thickness direction of the positive electrode current collector. It should be noted that the "surface" here can be the entire area of ​​the positive electrode current collector, or it can be a partial area of ​​the positive electrode current collector. There is no special restriction in the present application, as long as the purpose of the present application can be achieved.

[0062] In the present application, there is no particular restriction on the negative electrode current collector, as long as the purpose of the present application can be achieved, for example, it may include but is not limited to copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper or composite current collector, etc. In the present application, there is no particular restriction on the thickness of the negative electrode current collector, as long as the purpose of the present application can be achieved, for example, the thickness is 4μm to 12μm. In the present application, the negative electrode material layer can be arranged on one surface in the thickness direction of the negative electrode current collector, or on two surfaces in the thickness direction of the negative electrode current collector. It should be noted that the "surface" here can be the entire area of ​​the negative electrode current collector, or it can be a partial area of ​​the negative electrode current collector. There is no particular restriction in the present application, as long as the purpose of the present application can be achieved.

[0063] The present application has no particular restrictions on the positive electrode active material, the negative electrode active material and the isolation membrane, as long as the purpose of the present application can be achieved. For example, the positive electrode active material, the negative electrode active material and the isolation membrane can adopt the positive electrode active material, the negative electrode active material and the isolation membrane known in the art.

[0064] The electrochemical device of the present application also includes an electrolyte. The present application has no particular limitation on the electrolyte as long as the purpose of the present application can be achieved. For example, the electrolyte can be an electrolyte known in the art.

[0065] The electrochemical device of the present application is not particularly limited, and may include any device that undergoes an electrochemical reaction. In some embodiments, the electrochemical device may include, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a lithium polymer secondary battery, or a lithium ion polymer secondary battery, etc.

[0066] The preparation process of the electrochemical device is well known to those skilled in the art, and the present application has no particular limitation. For example, it may include but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and other operations as needed to obtain an electrode assembly of a wound structure, placing the electrode assembly in a packaging shell, injecting the electrolyte into the packaging shell and sealing it to obtain an electrochemical device; or stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and then fixing the four corners of the entire stacked structure with tape to obtain an electrode assembly of a stacked structure, placing the electrode assembly in a packaging shell, injecting the electrolyte into the packaging shell and sealing it to obtain an electrochemical device. In addition, overcurrent protection elements, guide plates, etc. may also be placed in the packaging shell as needed to prevent pressure rise and overcharge and discharge inside the electrochemical device.

[0067] The second aspect of the present application provides an electronic device, which includes the electrochemical device in any of the above embodiments. The electrochemical device provided by the present application has good safety performance, so the electronic device provided by the present application also has good safety performance.

[0068] The electronic device of the present application is not particularly limited, and it can be any electronic device known in the prior art. In some embodiments, the electronic device may include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.

[0069] The present application provides an electrochemical device and an electronic device, wherein the electrochemical device comprises a packaging shell, an electrode assembly contained in the packaging shell, and adhesive tape, wherein the electrode assembly comprises an electrode sheet, the electrode sheet comprises a current collector, the adhesive tape comprises a substrate layer and a first adhesive layer, the first adhesive layer comprises a first surface and a second surface opposite to the first surface, the first surface is adhered to one surface of the substrate layer, the second surface is adhered to the inner surface of the electrode assembly or the packaging shell, and the tensile strength of the substrate layer is σ 1 , the tensile strength of the current collector σ 2 150MPa to 500MPa, satisfying 2σ 2 ≤σ 1 ≤1500MPa. By adjusting the tensile strength relationship between the substrate layer and the current collector, the safety performance of the electrochemical device can be effectively improved.

[0070] Example

[0071] The following examples and comparative examples are given to more specifically describe the embodiments of the present application. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0072] Test methods and equipment:

[0073] Tensile strength test:

[0074] Punch out a 15mm wide and 70mm long test specimen from the substrate layer or current collector using a punching machine. Fix the specimen to the test fixture of the high-speed rail tensile machine to test the tensile strength of the specimen. The tensile speed is 5mm / min, and the standard distance between the two fixtures of the tensile machine is 50mm. Record the tensile strength and displacement curves, and the tensile strength sudden drop point is the tensile strength that resists external force damage.

[0075] Blunt puncture limit force and number of passes test

[0076] The lithium-ion battery was charged to 4.5V; a triangular rod extruder (model: DKBF-3KH, manufacturer: Dae Kyung) was used to extrude the lithium-ion battery with a round rod with a diameter of 6mm and a length of 6.7cm. The extrusion speed was 300N / min, and the test upper limit force was set to 3000N. When the pressure reached the upper limit value, the round rod was released; the pressure, displacement, temperature and voltage data were recorded during the measurement process.

[0077] The blunt puncture limit force is the maximum force that a lithium-ion battery can withstand to resist external force damage. The judgment standard is: the pressure drop point in the pressure-displacement curve is the blunt puncture limit force; 10 lithium-ion batteries are tested in each embodiment or comparative example, and the average value is taken as the final result.

[0078] Blunt puncture passing judgment standard: the lithium ion battery does not catch fire or explode. For each embodiment or comparative example, 10 lithium ion batteries are tested and the number of passing batteries is recorded.

[0079] Energy density test:

[0080] Place the lithium-ion battery in a 25℃ constant temperature box and let it stand for 30 minutes to allow the lithium-ion battery to reach a constant temperature. Charge the lithium-ion battery that has reached a constant temperature at a constant current of 0.5C to a voltage of 4.45V, then charge it at a constant voltage of 4.45V to a current of 0.05C, and discharge it at 0.5C to a voltage of 3.0V, and record the discharge energy.

[0081] Energy density = discharge energy / (length × width × thickness of lithium-ion battery).

[0082] Test of softening point of first and second adhesive layers:

[0083] The softening point of the first or second adhesive layer is measured using a ring and ball softening point tester (manufacturer: ISL, France, model: RB36 5G): melt the raw material sample for preparing the first or second adhesive layer into a uniform, bubble-free liquid, then heat the sample ring to the same temperature as the melted sample, place it on a smooth copper sheet coated with silicone grease, inject the melted sample into the sample ring, and make the liquid level slightly higher than the sample ring, and scrape off the excess sample after cooling. The measuring reagent is freshly boiled distilled water, which is heated to a rate of 5°C / min until the temperature indicated by the thermometer when the steel ball falls to the lower bottom plate after the sample softens is the softening point.

[0084] Example 1-1

[0085] <Preparation of positive electrode sheet>

[0086] The positive electrode active material lithium cobalt oxide, the conductive agent acetylene black, and the binder polyvinylidene fluoride are mixed in a mass ratio of 97.8:1.4:0.8, and N-methylpyrrolidone (NMP) is added. The system is stirred under the action of a vacuum mixer until it becomes uniform and transparent to obtain a positive electrode slurry, wherein the solid content of the positive electrode slurry is 70wt%. The positive electrode slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 12μm, and the aluminum foil is dried at 85°C for 1h to obtain a positive electrode sheet coated with a positive electrode material layer on one side. Repeat the above steps on the other surface of the aluminum foil to obtain a positive electrode sheet coated with a positive electrode material layer on both sides. Then, after cold pressing, cutting, and slitting, it is dried under vacuum conditions at 850°C for 1h to obtain a positive electrode sheet with a specification of 74mm×867mm. Among them, the tensile strength σ of the aluminum foil 2 It is 270MPa.

[0087] <Preparation of negative electrode sheet>

[0088] The negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are mixed in a mass ratio of 96.7:1:1:1.3, and deionized water is added to obtain a negative electrode slurry under the action of a vacuum mixer, wherein the solid content of the negative electrode slurry is 75wt%. The negative electrode slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 12μm, and the copper foil is dried at 85°C to obtain a negative electrode sheet with a coating thickness of 130μm and a negative electrode material layer coated on one side. Repeat the above steps on the other surface of the aluminum foil to obtain a negative electrode sheet with a negative electrode material layer coated on both sides. Then, after cold pressing, cutting, and slitting, it is dried under vacuum conditions at 85°C for 1h to obtain a negative electrode sheet with a specification of 74mm×867mm.

[0089] <Preparation of Electrolyte>

[0090] In a dry argon atmosphere glove box, ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) were mixed in a mass ratio of 20:30:20:30 to obtain an organic solvent, and then the organic solvent and lithium salt LiPF 6 and are uniformly mixed in a mass ratio of 92:8 to obtain an electrolyte.

[0091] <Preparation of Separator Film>

[0092] A porous PE film with a thickness of 7 μm (provided by Celgard Company) was used.

[0093] <Preparation of adhesive tape>

[0094] Preparation of the first adhesive layer slurry: The solute nitrile rubber and the solvent xylene are mixed and stirred evenly, and the solid content is 32%.

[0095] The slurry of the first adhesive layer is coated on one surface of the substrate layer, and after drying, a thickness D is obtained. 1 The base material is stainless steel (material), with a thickness of 24 μm and a tensile strength of σ 1 is 550MPa(σ 1 =2.04σ 2 ), the thickness of the first adhesive layer is 8μm and the softening point is 20℃.

[0096] <Preparation of lithium-ion batteries>

[0097] Weld the positive electrode tab on the positive electrode sheet, weld the negative electrode tab on the negative electrode sheet, then stack the positive electrode sheet, separator, and negative electrode sheet in order, so that the separator is between the positive electrode sheet and the negative electrode sheet to play an isolating role, and wind up to obtain an electrode assembly, the outermost layer of the electrode assembly is the positive electrode sheet. Paste the second surface of the first adhesive layer of the adhesive paper on the outermost positive electrode sheet of the electrode assembly, and the pasting position is as follows: Figure 1 As shown, the electrode assembly is then placed in an aluminum-plastic film packaging shell, and after drying, an electrolyte is injected, and a lithium-ion battery is obtained through vacuum packaging, standing, formation, degassing, trimming and other processes.

[0098] Example 1-2

[0099] In addition to σ 1 is 895MPa(σ 1 =3.31σ 2 ), the rest is the same as Example 1-1.

[0100] Examples 1-3

[0101] In addition to σ 1 1500MPa(σ 1 =5.56σ2 ), the rest is the same as Example 1-1.

[0102] Examples 1-4

[0103] In addition to pasting the adhesive tape I on both sides of the electrode assembly along the thickness direction (pasting position such as Figure 3 Except for the above, the rest is the same as Example 1-1.

[0104] Examples 1-5

[0105] In addition to pasting the adhesive tape I on the inner surface of the packaging shell close to the electrode assembly (pasting position such as Figure 4 Except for the above, the rest is the same as Example 1-1.

[0106] Examples 1-6

[0107] Except that the adhesive tape I is pasted on the connection part between the positive electrode ear and the positive electrode plate, the rest is the same as Example 1-1.

[0108] Examples 1-7

[0109] In addition to pasting the adhesive tape I between the positive electrode sheet of the second outer circle of the electrode assembly and the positive electrode sheet of the outermost circle of the electrode assembly, the first adhesive layer is pasted on the surface of the outermost circle of the positive electrode sheet away from the packaging shell (pasting position is as follows Fig.11 Except for the above, the rest is the same as Example 1-1.

[0110] Examples 1-8

[0111] In addition to pasting the adhesive tape I on the positive electrode sheet opposite to the connection part between the negative electrode ear and the negative electrode ear (pasting position is as follows Fig. 9 Except for the above, the rest is the same as Example 1-1.

[0112] Examples 1-9

[0113] Preparation of the second adhesive layer slurry: The solute styrene butadiene rubber and the solvent toluene are mixed and stirred evenly, and the solid content is 32wt%.

[0114] The slurry of the second adhesive layer is coated on the other surface of the base material layer of the adhesive tape in Example 1-1, and after drying, the thickness of the adhesive tape II is obtained. 2 The thickness of the second adhesive layer is 8 μm and the softening point is 70°C.

[0115] In addition to pasting the above-prepared adhesive tape II on the outermost positive electrode sheet of the electrode assembly (pasting position such as Fig.12 As shown), the first adhesive layer is adhered to the surface of the outermost positive electrode sheet of the electrode assembly, and the second adhesive layer is adhered to the inner surface of the packaging shell close to the electrode assembly, and the rest is the same as Example 1-1.

[0116] Examples 1-10

[0117] In addition to pasting the adhesive tape II on both sides of the electrode assembly along the thickness direction (pasting position such as Fig.13 Except for the above, the rest is the same as Example 1-9.

[0118] Embodiment 1-11

[0119] In addition to pasting the adhesive tape II on the connection area between the positive electrode ear and the positive electrode sheet, the first adhesive layer is pasted on the connection area, and the second adhesive layer is pasted on the isolation film adjacent to the connection area (the pasting position is the same as the Fig.14 and Fig.15 Similar), the rest is the same as Example 1-9.

[0120] Examples 1-12

[0121] In addition to pasting the adhesive tape II on the connection area between the positive electrode ear and the positive electrode sheet, the first adhesive layer is pasted on the connection area, and the second adhesive layer is pasted on the separator adjacent to the connection area; and the first adhesive layer of the adhesive tape II is pasted on the other surface of the positive electrode sheet that is not connected to the positive electrode ear and the pasting position is opposite to the connection area, and the second adhesive layer of the adhesive tape II is pasted on the separator adjacent to the other surface of the positive electrode sheet and the pasting position is opposite to the connection area (the pasting position is opposite to the connection area). Fig.16 Similar), the rest is the same as Example 1-9.

[0122] Examples 1-13

[0123] In addition to pasting the adhesive tape II on the connection area between the negative electrode tab and the negative electrode sheet, the first adhesive layer is pasted on the connection area, and the second adhesive layer is pasted on the separator adjacent to the connection area; and the first adhesive layer of the adhesive tape II is pasted on the other surface of the negative electrode sheet that is not connected to the negative electrode tab and the pasting position is opposite to the connection area, and the second adhesive layer of the adhesive tape II is pasted on the separator adjacent to the other surface of the negative electrode sheet and the pasting position is opposite to the connection area (the pasting position is as shown in FIG. Fig.16 Except for the above, the rest is the same as Example 1-9.

[0124] Example 2-1

[0125] In addition to the thickness D of the adhesive tape Ⅰ 1 The thickness of the substrate layer is 20 μm and 8 μm (0.4D 1 ), the thickness of the first adhesive layer is 12μm (0.6D 1 ), the rest is the same as implementation 1-1.

[0126] Example 2-2

[0127] In addition to the thickness D of the adhesive tape Ⅰ 1 The thickness of the substrate layer is 200 μm and 180 μm (0.9D 1 ), the thickness of the first adhesive layer is 20μm (0.1D 1 ), the rest is the same as implementation 1-1.

[0128] Example 2-3

[0129] In addition to the thickness D of the adhesive tape II 2 The thickness of the substrate layer is 30 μm and 7.2 μm (0.24D 2 ), the thickness of the first adhesive layer is 11.4μm (0.38D 2 ), the thickness of the second adhesive layer is 11.4μm (0.38D 2 ), the rest is the same as implementation 1-9.

[0130] Embodiment 2-4

[0131] In addition to the thickness D of the adhesive tape II 2 The thickness of the substrate layer is 320 μm and 262.4 μm (0.82D 2 ), the thickness of the first adhesive layer is 28.8μm (0.09D 2 ), the thickness of the second adhesive layer is 28.8μm (0.09D 2 ), the rest is the same as implementation 1-9.

[0132] Embodiment 2-5

[0133] In addition to replacing the substrate layer with nickel metal, the tensile strength σ 1 is 594MPa(σ 1 =2.2σ 2 ), the rest is the same as Example 1-1.

[0134] Comparative Example 1-1

[0135] Except that the adhesive tape is not affixed, the rest is the same as Example 1-1.

[0136] Comparative Example 1-2

[0137] In addition to σ 1 is 268MPa(σ 1 =0.99σ 2 ), the rest is the same as Example 1-1.

[0138] The preparation parameters and performance tests of various embodiments and comparative examples are shown in Tables 1 and 2.

[0139] Table 1

[0140]

[0141] Note: “ / ” in Table 1 indicates that there is no corresponding preparation parameter.

[0142] It can be seen from Examples 1-1 to 1-13 and Comparative Example 1-1 that when the electrochemical device includes the adhesive tape of the present application, the safety performance of the electrochemical device can be improved, and the electrochemical device has a higher energy density. It can be seen from Examples 1-1 to 1-13 and Comparative Example 1-2 that when the tensile strength of the substrate layer and the tensile strength of the current collector are within the range of the present application, the safety performance of the electrochemical device can be improved, and the electrochemical device has a higher energy density. It can be seen from Examples 1-1 to 1-13 that the different pasting positions of the adhesive tape have a certain influence on the safety performance and energy density of the electrochemical device, and the obtained electrochemical device has both good safety performance and high energy density.

[0143] Table 2

[0144]

[0145] Note: “ / ” in Table 2 indicates that there is no corresponding preparation parameter.

[0146] The thickness of the adhesive tape, substrate layer, first adhesive layer and second adhesive layer and the material of the substrate layer usually affect the performance of the electrochemical device, such as safety performance and energy density. It can be seen from Example 1-1, Example 2-1 and Example 2-2 that the thickness of the adhesive tape, substrate layer and first adhesive layer is within the scope of the present application, and the obtained electrochemical device has both good safety performance and high energy density. It can be seen from Example 1-9, Example 2-3 and Example 2-4 that the thickness of the adhesive tape, substrate layer, first adhesive layer and second adhesive layer is within the scope of the present application, and the obtained electrochemical device has both good safety performance and high energy density. It can be seen from Example 1-1 and Example 2-5 that the material of the substrate layer is within the scope of the present application, and the obtained electrochemical device has both good safety performance and high energy density.

[0147] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An electrochemical device, comprising a packaging shell, an electrode assembly contained in the packaging shell, and adhesive tape, wherein the electrode assembly comprises an electrode sheet, the electrode sheet comprises a current collector, the adhesive tape comprises a substrate layer and a first adhesive layer, the first adhesive layer comprises a first surface and a second surface opposite to the first surface, characterized in that: The first surface is adhered to one surface of the substrate layer, the second surface is adhered to the inner surface of the electrode assembly or the packaging shell, the tensile strength of the substrate layer is σ1, the tensile strength σ2 of the current collector is 150MPa to 500MPa, and 2σ2≤σ1≤1500MPa is satisfied.

2. The electrochemical device according to claim 1, wherein: The second surface is adhered to the outermost layer of the electrode assembly.

3. The electrochemical device according to claim 1, wherein The second surface is adhered to the inner surface of the packaging case close to the electrode assembly.

4. The electrochemical device according to claim 1, wherein The electrode assembly includes a pole ear, the pole ear is electrically connected to a surface of the pole piece, the pole piece includes a connecting portion where the pole ear is connected to the pole piece, and the electrochemical device satisfies at least one of the following features: (i) the first adhesive layer covers the connecting portion; (ii) the first adhesive layer covers the connecting portion, and the first adhesive layer is adhered to another surface of the electrode and the adhesion position is opposite to the connecting portion; (iii) The first adhesive layer is adhered to another electrode having a polarity opposite to that of the electrode and the adhesion position is opposite to the position of the connecting portion.

5. The electrochemical device according to claim 1, wherein The electrode assembly includes a pole ear, the pole piece is provided with a groove, and the pole ear is arranged in the groove. The first adhesive layer covers the groove, or the first adhesive layer is adhered to another pole piece with a polarity opposite to that of the pole piece and the adhesion position is opposite to the position of the groove.

6. The electrochemical device according to claim 1, wherein The electrode assembly is a winding structure, the adhesive tape is arranged between the outer surface of the secondary outer circle of the electrode assembly and the inner surface of the outermost circle of the electrode assembly, and the second surface of the first adhesive layer is adhered to the outer surface of the secondary outer circle of the electrode assembly or the inner surface of the outermost circle of the electrode assembly.

7. The electrochemical device according to claim 1, wherein: The material of the substrate layer includes at least one of metal, non-metal, polymer material and composite material.

8. The electrochemical device according to any one of claims 1 to 7, wherein: The thickness D1 of the adhesive tape is 20 μm to 200 μm, the thickness of the substrate layer is 0.4D1 to 0.9D1, and the thickness of the first adhesive layer is 0.1D1 to 0.6D1.

9. The electrochemical device according to claim 1, wherein: A second adhesive layer is provided on the other surface of the substrate layer. When the second surface is pasted on the electrode assembly, the surface of the second adhesive layer facing away from the substrate layer is pasted on the inner surface of the packaging shell; or, when the second surface is pasted on the inner surface of the packaging shell, the surface of the second adhesive layer facing away from the substrate layer is pasted on the electrode assembly.

10. The electrochemical device according to claim 1, wherein The other surface of the substrate layer is provided with a second adhesive layer, the electrode assembly includes a pole ear, the pole ear is electrically connected to a surface of the pole piece, the pole piece includes a connection area where the pole ear is connected to the pole piece, and the electrochemical device satisfies at least one of the following characteristics: (iv) the adhesive tape covers the connection area; (v) the adhesive tape covers the connection area, and the adhesive tape is adhered to the other surface of the electrode and the adhesion position is opposite to the connection area; (vi) The adhesive tape is pasted on another electrode with opposite polarity to the electrode and the pasting position is opposite to the connection area.

11. The electrochemical device according to claim 9 or 10, wherein: The thickness D2 of the adhesive tape is 30 μm to 320 μm, the thickness of the substrate layer is 0.24D2 to 0.82D2, the thickness of the first adhesive layer is 0.09D2 to 0.38D2, ​​and the thickness of the second adhesive layer is 0.09D2 to 0.38D2.

12. The electrochemical device according to claim 9 or 10, wherein: The softening point of the second adhesive layer is greater than the softening point of the first adhesive layer.

13. An electronic device comprising the electrochemical device according to any one of claims 1 to 12.

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