Pole piece, electrochemical device, and electronic device comprising the same

Abstract

This application discloses an electrode, an electrochemical device, and an electronic device comprising the same. The electrode, by defining L1, L2, L3, and L4 to satisfy the formulas L1>L2>0, L3>L4>0, L3>L1, and 5≤L3+L4-L1-L2≤51, allows the first, second, third, and fourth coatings to fully exert their respective functions, thereby effectively suppressing the formation of cracks in the electrochemical device during charge-discharge cycles and improving the cycle life of the electrochemical device.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and more specifically, to electrodes, electrochemical devices, and electronic devices comprising the same. Background Technology

[0002] Lithium-ion secondary batteries and other electrochemical devices are widely used in portable electronic devices and electric vehicles due to their high energy density and long cycle life. During the manufacturing process of lithium-ion secondary batteries and other electrochemical devices, the thickness of the wound electrode structure varies abruptly at the junction of the single-sided coating area (single-sided coating region) and the double-sided coating area (double-sided coating region).

[0003] When the electrode is rolled to increase its compaction density, uneven stress occurs at the junction of the single-sided and double-sided coated areas due to abrupt thickness changes. This causes initial damage to the electrode's microstructure, including deformation of the current collector, breakage of active material particles, and interfacial delamination between the current collector and the active material. During subsequent charge-discharge cycles in lithium-ion batteries and other electrochemical devices, especially under repeated stress impacts from electrode volume expansion, this initial damage can become the starting point for crack propagation, ultimately leading to electrode fracture and the formation of cracks. The formation of cracks causes some of the active material in the electrode to lose its electrical connection, resulting in rapid capacity decay and a sharp increase in internal resistance in lithium-ion batteries and other electrochemical devices, severely impacting their cycle life.

[0004] Therefore, it is of great significance to develop an electrode that can suppress the formation of cracks in electrochemical devices during charge-discharge cycles. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of the prior art by providing an electrode, an electrochemical device, and an electronic device comprising the electrode.

[0006] To achieve the above objectives, this application provides an electrode sheet, the electrode sheet including a current collector, the current collector including a first surface and a second surface disposed opposite to each other; The first surface is provided with a first active material layer and a first reinforcing coating. The first reinforcing coating includes a first coating and a second coating. The first coating is located between the current collector and the second coating. At least a portion of the first active material layer is provided on the surface of a portion of the first reinforcing coating. The second surface is provided with a second active material layer and a second reinforcing coating. The second reinforcing coating includes a third coating and a fourth coating. The third coating is located between the current collector and the fourth coating. The surface of the second reinforcing coating is provided with at least a portion of the second active material layer. The first coating and the third coating each independently include a first binder and a first conductive agent, and the second coating and the fourth coating each independently include second inorganic particles, a second binder and a second conductive agent; Along the electrode winding direction, the distance between the tail end of the first active material layer and the tail end of the electrode is greater than the distance between the tail end of the second active material layer and the tail end of the electrode; the area where the orthographic projection of the second active material layer on the electrode coincides with the orthographic projection of the first active material layer on the electrode is a double-sided coating area, and the rest is a single-sided coating area; the beginning and end of the first coating layer and the second coating layer do not coincide, and the beginning and end of the third coating layer and the fourth coating layer do not coincide; the length of the first coating layer is L1 mm, the length of the second coating layer is L2 mm, the length of the third coating layer is L3 mm, and the length of the fourth coating layer is L4 mm, where L1, L2, L3, and L4 satisfy: L1 > L2 > 0; L3 > L4 > 0; L3 > L1; 5≤L3+L4-L1-L2≤51.

[0007] In this application, the second and fourth coatings provide localized hardness and compressive strength, resisting the pressure of electrode rolling in a "hard-on" manner. They directly resist the instantaneous high pressure and shear force of the rolling process, protecting the first and third coatings and the current collector, and reducing initial damage to the electrode. The first and third coatings provide high elasticity and adhesion, which not only disperses the energy from the current collector, the second coating, the fourth coating, and cyclic stress, preventing the initiation of cracks, but also stably connects the current collector and the second and fourth coatings into a whole, allowing the second and fourth coatings to better protect the current collector and reducing the dispersed and concentrated expansion force, thereby reducing the single-point expansion force. Based on this, L1, L2, L3, and L4 are constrained to satisfy the formulas L1>L2>0, L3>L4>0, L3>L1, 5≤L3+L4-L1-L2≤51, allowing the first, second, third, and fourth coatings to fully exert their respective functions, thereby effectively suppressing the generation of cracks in the electrochemical device during charge-discharge cycles and improving the cycle life of the electrochemical device.

[0008] In addition, when the beginning and end of the first and second coatings do not coincide, and the beginning and end of the third and fourth coatings do not coincide, step stress concentration can be prevented, which helps to suppress the generation of cracks in the electrochemical device during charge and discharge cycles and improve the cycle life of the electrochemical device.

[0009] In some implementations, 20 ≤ L3 + L4 - L1 - L2 ≤ 35.

[0010] In some implementations, 5 ≤ L1 ≤ 26.

[0011] In some implementations, 3 ≤ L2 ≤ 24.

[0012] In some implementations, 7 ≤ L3 ≤ 30.

[0013] In some implementations, 6 ≤ L4 ≤ 29.

[0014] In some embodiments, the height of the first coating is H1 μm, the height of the second coating is H2 μm, the height of the third coating is H3 μm, and the height of the fourth coating is H4 μm, wherein H1, H2, H3, and H4 satisfy: 0.2≤H2 / H1≤40; 0.2≤H4 / H3≤40.

[0015] In some implementations, 10 ≤ H2 / H1 ≤ 30.

[0016] In some implementations, 10 ≤ H4 / H3 ≤ 30.

[0017] In some implementations, H3+H4-H1-H2≥0.

[0018] In some implementations, 0.2 ≤ H1 ≤ 5.

[0019] In some implementations, 1 ≤ H2 ≤ 8.

[0020] In some implementations, 0.2 ≤ H3 ≤ 5.

[0021] In some implementations, 1 ≤ H4 ≤ 8.

[0022] In some embodiments, the mass percentage of the first adhesive is N1, based on the mass of the first coating, where 60% ≤ N1 ≤ 90%.

[0023] In some embodiments, the first coating further includes first inorganic particles.

[0024] In some embodiments, the mass percentage of the first inorganic particles is K1, where 0% ≤ K1 ≤ 10%, based on the mass of the first coating.

[0025] Adding an appropriate amount of first inorganic particles to the first coating can moderately increase the modulus of the first coating and achieve a gradient transition between the second coating and the first coating. This is beneficial for further suppressing the generation of fragments in the electrochemical device during charge-discharge cycles, thereby further improving the cycle life of the electrochemical device.

[0026] In some embodiments, the mass percentage of the first conductive agent is D1, based on the mass of the first coating, where 1% ≤ D1 ≤ 40%.

[0027] In some embodiments, the mass percentage of the second adhesive is N2, based on the mass of the second coating, where 1% ≤ N2 ≤ 20%.

[0028] In some embodiments, the mass percentage of the second inorganic particles is K2, based on the mass of the second coating, where 60% ≤ K2 ≤ 98%.

[0029] In some embodiments, the mass percentage of the second conductive agent is D2, based on the mass of the second coating, where 1% ≤ D2 ≤ 20%.

[0030] In some embodiments, the mass percentage of the first adhesive is N3, based on the mass of the third coating, where 60% ≤ N3 ≤ 90%.

[0031] In some embodiments, the third coating further includes first inorganic particles.

[0032] In some embodiments, the mass percentage of the first inorganic particles is K3, where 0% ≤ K3 ≤ 10%, based on the mass of the third coating.

[0033] Adding an appropriate amount of first inorganic particles to the third coating can moderately increase the modulus of the third coating and achieve a gradient transition between the fourth and third coatings. This is beneficial for further suppressing the generation of fragments in the electrochemical device during charge-discharge cycles, thereby further improving the cycle life of the electrochemical device.

[0034] In some embodiments, the mass percentage of the first conductive agent is D3, based on the mass of the third coating, where 1% ≤ D3 ≤ 40%.

[0035] In some embodiments, the mass percentage of the second adhesive is N4, based on the mass of the fourth coating, where 1% ≤ N4 ≤ 20%.

[0036] In some embodiments, the mass percentage of the second inorganic particles is K4, based on the mass of the fourth coating, where 60% ≤ K4 ≤ 98%.

[0037] In some embodiments, the mass percentage of the second conductive agent is D4, based on the mass of the fourth coating, where 1% ≤ D4 ≤ 20%.

[0038] In some embodiments, in the first coating and / or the third coating, the first adhesive includes at least one of an acrylic polymer, polyurethane, polyvinyl alcohol (PVA), a polyvinyl alcohol derivative, and polyimide.

[0039] In some embodiments, the acrylic-containing polymer includes polyacrylic acid.

[0040] In some embodiments, the first inorganic particles in the first coating and / or the third coating include at least one of alumina, silicon dioxide, titanium dioxide, boehmite, boron nitride, and silicon carbide.

[0041] In some embodiments, the average particle size Dv50 of the first inorganic particles in the first coating and / or the third coating is 50-800 nm.

[0042] In some embodiments, the first conductive agent in the first coating and / or the third coating includes at least one of carbon, carbon black, graphite, expanded graphite, graphene, acetylene black, Ketjen black, carbon fiber, graphitized carbon sheet, and carbon nanotube.

[0043] In some embodiments, in the second coating and / or the fourth coating, the second adhesive comprises at least one of an acrylic polymer, polyurethane, polyvinyl alcohol (PVA), a polyvinyl alcohol derivative, and polyimide.

[0044] In some embodiments, the acrylic-containing polymer includes polyacrylic acid.

[0045] In some embodiments, the second inorganic particles in the second coating and / or the fourth coating include at least one of alumina, silicon dioxide, titanium dioxide, boehmite, boron nitride, and silicon carbide.

[0046] In some embodiments, the average particle size Dv50 of the second inorganic particles in the second coating and / or the fourth coating is 50-800 nm.

[0047] In some embodiments, the second conductive agent in the second coating and / or the fourth coating includes at least one of carbon, carbon black, graphite, expanded graphite, graphene, acetylene black, Ketjen black, carbon fiber, graphitized carbon sheet, and carbon nanotube.

[0048] In some embodiments, the first adhesive and the second adhesive are the same or similar.

[0049] In this application, when the first adhesive and the second adhesive are the same or similar, a stronger chemical bond and physical interweaving will be formed between the first coating and the second coating, and between the third coating and the fourth coating. This is more conducive to interfacial adhesion and allows the first, second, third and fourth coatings to play their respective roles better. This is beneficial to further suppress the generation of cracks in the electrochemical device during charge and discharge cycles, thereby improving the cycle life of the electrochemical device.

[0050] In some embodiments, along the electrode winding direction, the first coating perpendicular to the first center line of the length direction, the second coating perpendicular to the second center line of the length direction, the third coating perpendicular to the third center line of the length direction, and the fourth coating perpendicular to the fourth center line of the length direction coincide with each other.

[0051] This application provides an electrochemical device including the electrode described above.

[0052] This application also provides an electronic device that includes the electrochemical device described above.

[0053] Compared with the prior art, the beneficial effects of this application are as follows: In this application, the second and fourth coatings provide localized hardness and compressive strength, resisting the pressure of electrode rolling in a "hard-on" manner. They directly resist the instantaneous high pressure and shear force of the rolling process, protecting the first and third coatings and the current collector, and reducing initial damage to the electrode. The first and third coatings provide high elasticity and adhesion, which not only disperses the energy from the current collector, the second coating, the fourth coating, and cyclic stress, preventing the initiation of cracks, but also stably connects the current collector and the second and fourth coatings into a whole, allowing the second and fourth coatings to better protect the current collector and reducing the dispersed and concentrated expansion force, thereby reducing the single-point expansion force. Based on this, L1, L2, L3, and L4 are constrained to satisfy the formulas L1>L2>0, L3>L4>0, L3>L1, 5≤L3+L4-L1-L2≤51, allowing the first, second, third, and fourth coatings to fully exert their respective functions, thereby effectively suppressing the generation of cracks in the electrochemical device during charge-discharge cycles and improving the cycle life of the electrochemical device.

[0054] In addition, when the beginning and end of the first and second coatings do not coincide, and the beginning and end of the third and fourth coatings do not coincide, step stress concentration can be prevented, which helps to suppress the generation of cracks in the electrochemical device during charge and discharge cycles and improve the cycle life of the electrochemical device.

[0055] Adding an appropriate amount of first inorganic particles to the first coating can moderately increase the modulus of the first coating and achieve a gradient transition between the second coating and the first coating. This is beneficial for further suppressing the generation of fragments in the electrochemical device during charge-discharge cycles, thereby further improving the cycle life of the electrochemical device.

[0056] Adding an appropriate amount of first inorganic particles to the third coating can moderately increase the modulus of the third coating and achieve a gradient transition between the fourth and third coatings. This is beneficial for further suppressing the generation of fragments in the electrochemical device during charge-discharge cycles, thereby further improving the cycle life of the electrochemical device.

[0057] In this application, when the first adhesive and the second adhesive are the same or similar, a stronger chemical bond and physical interweaving will be formed between the first coating and the second coating, and between the third coating and the fourth coating. This is more conducive to interfacial adhesion and allows the first, second, third and fourth coatings to play their respective roles better. This is beneficial to further suppress the generation of cracks in the electrochemical device during charge and discharge cycles, thereby improving the cycle life of the electrochemical device. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the structure of the electrode (positive electrode) in Example 1. In the figure, 1-first coating, 2-second coating, 3-third coating, 4-fourth coating, 5-first active material layer, 6-second active material layer, and 7-positive current collector.

[0059] Figure 2 The diagram shows the structure of the comparative example 10 electrode (positive electrode). In the diagram, 1-first coating, 2-second coating, 3-third coating, 4-fourth coating, 5-first active material layer, 6-second active material layer, and 7-positive current collector. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] <General Definition> The term "average particle size Dv50" refers to the particle size value that corresponds to a cumulative volume percentage of 50% in a particle group.

[0062] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0063] The embodiments of this application may omit unnecessary detailed descriptions. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0064] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0065] In this application, a list of items connected by the term "at least one of" can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.

[0066] In the following description, all figures disclosed in this application are approximate values, regardless of whether the terms "about" or "approximately" are used in conjunction. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a range of values ​​with a lower limit (RL) and an upper limit (RU) is disclosed, any values ​​falling within that range are specifically disclosed. Specifically, the following values ​​within this range are specifically disclosed: R = RL + k * (RU - RL), where k is a variable with a 1% increment from 1% to 100%, i.e., k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any range of values ​​defined by the two R values ​​as defined above are also specifically disclosed.

[0067] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form a range not explicitly stated.

[0068] Throughout this specification, references to "implementation," "partial implementation," "one implementation," "some implementations," "another implementation," "specific implementation," or "partial implementation" mean that at least one implementation or embodiment in this application includes the specific features, structures, materials, or characteristics described in that implementation or embodiment.

[0069] I. Electrode This application provides an electrode sheet, the electrode sheet including a current collector, the current collector including a first surface and a second surface disposed opposite to each other; The first surface is provided with a first active material layer and a first reinforcing coating. The first reinforcing coating includes a first coating and a second coating. The first coating is located between the current collector and the second coating. At least a portion of the first active material layer is provided on the surface of a portion of the first reinforcing coating. The second surface is provided with a second active material layer and a second reinforcing coating. The second reinforcing coating includes a third coating and a fourth coating. The third coating is located between the current collector and the fourth coating. The surface of the second reinforcing coating is provided with at least a portion of the second active material layer. The first coating and the third coating each independently include a first binder and a first conductive agent, and the second coating and the fourth coating each independently include second inorganic particles, a second binder and a second conductive agent; Along the electrode winding direction, the distance between the tail end of the first active material layer and the tail end of the electrode is greater than the distance between the tail end of the second active material layer and the tail end of the electrode; the area where the orthographic projection of the second active material layer on the electrode coincides with the orthographic projection of the first active material layer on the electrode is the double-sided coating area, and the rest is the single-sided coating area; the beginning and end ends of the first coating layer and the second coating layer do not coincide, and the beginning and end ends of the third coating layer and the fourth coating layer do not coincide; the length of the first coating layer is L1 mm, the length of the second coating layer is L2 mm, the length of the third coating layer is L3 mm, and the length of the fourth coating layer is L4 mm, where L1, L2, L3, and L4 satisfy: L1 > L2 > 0; L3 > L4 > 0; L3 > L1; 5≤L3+L4-L1-L2≤51.

[0070] In this application, the second and fourth coatings provide localized hardness and compressive strength, resisting the pressure of electrode rolling in a "hard-on" manner. They directly resist the instantaneous high pressure and shear force of the rolling process, protecting the first and third coatings and the current collector, and reducing initial damage to the electrode. The first and third coatings provide high elasticity and adhesion, which not only disperses the energy from the current collector, the second coating, the fourth coating, and cyclic stress, preventing the initiation of cracks, but also stably connects the current collector and the second and fourth coatings into a whole, allowing the second and fourth coatings to better protect the current collector and reducing the dispersed and concentrated expansion force, thereby reducing the single-point expansion force. Based on this, L1, L2, L3, and L4 are constrained to satisfy the formulas L1>L2>0, L3>L4>0, L3>L1, 5≤L3+L4-L1-L2≤51, allowing the first, second, third, and fourth coatings to fully exert their respective functions, thereby effectively suppressing the generation of cracks in the electrochemical device during charge-discharge cycles and improving the cycle life of the electrochemical device.

[0071] In addition, when the beginning and end of the first and second coatings do not coincide, and the beginning and end of the third and fourth coatings do not coincide, step stress concentration can be prevented, which helps to suppress the generation of cracks in the electrochemical device during charge and discharge cycles and improve the cycle life of the electrochemical device.

[0072] In some implementations, L3+L4-L1-L2 can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, or 51, or fall within the range of any two of the above values.

[0073] In some implementations, 20 ≤ L3 + L4 - L1 - L2 ≤ 35.

[0074] In some implementations, 5 ≤ L1 ≤ 26.

[0075] In some implementations, L1 can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26, or be within the range of any two of the above values.

[0076] In some implementations, 3 ≤ L2 ≤ 24.

[0077] In some implementations, L2 can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24, or be within the range of any two of the above values.

[0078] In some implementations, 7 ≤ L3 ≤ 30.

[0079] In some implementations, L3 can be 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30, or be within the range of any two of the above values.

[0080] In some implementations, 6 ≤ L4 ≤ 29.

[0081] In some implementations, L4 can be 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 or 29, or be within the range of any two of the above values.

[0082] In some embodiments, the height of the first coating is H1 μm, the height of the second coating is H2 μm, the height of the third coating is H3 μm, and the height of the fourth coating is H4 μm, wherein H1, H2, H3, and H4 satisfy: 0.2≤H2 / H1≤40; 0.2≤H4 / H3≤40.

[0083] In some implementations, H2 / H1 can be 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, 10, 10.2, 10.5, 10.8, 11, 11. 2, 11.5, 11.8, 12, 12.2, 12.5, 12.8, 13, 13.2, 13.5, 13.8, 14, 14.2, 14.5, 14.8, 15, 15.2, 15.5, 15.8, 16, 16.2, 16.5, 16.8, 17, 17.2, 17.5, 17.8, 18, 18.2, 18.5, 18.8, 19, 19.2, 19.5, 19.8, 20, 20.2, 20.5, 20.8, 21, 21. 2, 21.5, 21.8, 22, 22.2, 22.5, 22.8, 23, 23.2, 23.5, 23.8, 24, 24.2, 24.5, 24.8, 25, 25.2, 25.5, 25.8, 26, 26.2, 26.5, 26.8, 27, 27.2, 27.5, 27.8, 28, 28.2, 28.5, 28.8, 29, 29.2, 29.5, 29.8, 30, 30.2, 30.5, 30.8, 31, 31 2, 31.5, 31.8, 32, 32.2, 32.5, 32.8, 33, 33.2, 33.5, 33.8, 34, 34.2, 34.5, 34.8, 35, 35.2, 35.5, 35.8, 36, 36.2, 36.5, 36.8, 37, 37.2, 37.5, 37.8, 38, 38.2, 38.5, 38.8, 39, 39.2, 39.5, 39.8 or 40, or within the range of any two of the above values.

[0084] In some implementations, 10 ≤ H2 / H1 ≤ 30.

[0085] In some implementations, H4 / H3 can be 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, 10, 10.2, 10.5, 10.8, 11, 11. 2, 11.5, 11.8, 12, 12.2, 12.5, 12.8, 13, 13.2, 13.5, 13.8, 14, 14.2, 14.5, 14.8, 15, 15.2, 15.5, 15.8, 16, 16.2, 16.5, 16.8, 17, 17.2, 17.5, 17.8, 18, 18.2, 18.5, 18.8, 19, 19.2, 19.5, 19.8, 20, 20.2, 20.5, 20.8, 21, 21. 2, 21.5, 21.8, 22, 22.2, 22.5, 22.8, 23, 23.2, 23.5, 23.8, 24, 24.2, 24.5, 24.8, 25, 25.2, 25.5, 25.8, 26, 26.2, 26.5, 26.8, 27, 27.2, 27.5, 27.8, 28, 28.2, 28.5, 28.8, 29, 29.2, 29.5, 29.8, 30, 30.2, 30.5, 30.8, 31, 31 2, 31.5, 31.8, 32, 32.2, 32.5, 32.8, 33, 33.2, 33.5, 33.8, 34, 34.2, 34.5, 34.8, 35, 35.2, 35.5, 35.8, 36, 36.2, 36.5, 36.8, 37, 37.2, 37.5, 37.8, 38, 38.2, 38.5, 38.8, 39, 39.2, 39.5, 39.8 or 40, or within the range of any two of the above values.

[0086] In some implementations, 10 ≤ H4 / H3 ≤ 30.

[0087] In some implementations, H3+H4-H1-H2≥0.

[0088] In some implementations, H3+H4-H1-H2 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5, or fall within the range of any two of the above values.

[0089] In some implementations, 0 ≤ H3 + H4 - H1 - H2 ≤ 4.5.

[0090] In some implementations, 0.2 ≤ H1 ≤ 5.

[0091] In some implementations, H1 can be 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8 or 5, or fall within the range of any two of the above values.

[0092] In some implementations, 1 ≤ H2 ≤ 8.

[0093] In some implementations, H2 can be 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8 or 8, or fall within the range of any two of the above values.

[0094] In some implementations, 0.2 ≤ H3 ≤ 5.

[0095] In some implementations, H3 can be 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8 or 5, or fall within the range of any two of the above values.

[0096] In some implementations, 1 ≤ H4 ≤ 8.

[0097] In some implementations, H4 can be 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8 or 8, or fall within the range of any two of the above values.

[0098] In some embodiments, the mass percentage of the first adhesive is N1, based on the mass of the first coating, where 60% ≤ N1 ≤ 90%.

[0099] In some embodiments, the mass percentage of the first adhesive is N1 based on the mass of the first coating. N1 can be 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, or 90%, or fall within the range of any two of the above values.

[0100] In some embodiments, the first coating further includes first inorganic particles.

[0101] In some embodiments, the mass percentage of the first inorganic particles is K1, where 0% ≤ K1 ≤ 10%, based on the mass of the first coating.

[0102] In some embodiments, the mass percentage of the first inorganic particles is K1 based on the mass of the first coating. K1 can be 0%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, or 10%, or fall within the range of any two of the above values.

[0103] Adding an appropriate amount of first inorganic particles to the first coating can moderately increase the modulus of the first coating and achieve a gradient transition between the second coating and the first coating. This is beneficial for further suppressing the generation of fragments in the electrochemical device during charge-discharge cycles, thereby further improving the cycle life of the electrochemical device.

[0104] In some embodiments, the mass percentage of the first conductive agent is D1, based on the mass of the first coating, where 1% ≤ D1 ≤ 40%.

[0105] In some embodiments, the mass percentage of the first conductive agent is D1 based on the mass of the first coating. D1 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, or fall within the range of any two of the above values.

[0106] In some embodiments, the mass percentage of the second adhesive is N2, based on the mass of the second coating, where 1% ≤ N2 ≤ 20%.

[0107] In some embodiments, the mass percentage of the second adhesive is N2 based on the mass of the second coating. N2 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, or fall within the range of any two of the above values.

[0108] In some embodiments, the mass percentage of the second inorganic particles is K2, based on the mass of the second coating, where 60% ≤ K2 ≤ 98%.

[0109] In some embodiments, the mass percentage of the second inorganic particles is K2 based on the mass of the second coating. K2 can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, or 98%, or fall within the range of any two of the above values.

[0110] In some embodiments, the mass percentage of the second conductive agent is D2, based on the mass of the second coating, where 1% ≤ D2 ≤ 20%.

[0111] In some embodiments, the mass percentage of the second conductive agent is D2 based on the mass of the second coating. D2 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, or fall within the range of any two of the above values.

[0112] In some embodiments, the mass percentage of the first adhesive is N3, based on the mass of the third coating, where 60% ≤ N3 ≤ 90%.

[0113] In some embodiments, the mass percentage of the first adhesive is N3 based on the mass of the third coating. N3 can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, or 90%, or fall within the range of any two of the above values.

[0114] In some embodiments, the third coating further includes first inorganic particles.

[0115] In some embodiments, the mass percentage of the first inorganic particles is K3, where 0% ≤ K3 ≤ 10%, based on the mass of the third coating.

[0116] In some embodiments, the mass percentage of the first inorganic particles is K3 based on the mass of the third coating. K3 can be 0%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, or 10%, or fall within the range of any two of the above values.

[0117] Adding an appropriate amount of first inorganic particles to the third coating can moderately increase the modulus of the third coating and achieve a gradient transition between the fourth and third coatings. This is beneficial for further suppressing the generation of fragments in the electrochemical device during charge-discharge cycles, thereby further improving the cycle life of the electrochemical device.

[0118] In some embodiments, the mass percentage of the first conductive agent is D3, based on the mass of the third coating, where 1% ≤ D3 ≤ 40%.

[0119] In some embodiments, the mass percentage of the first conductive agent is D3 based on the mass of the third coating. D3 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, or fall within the range of any two of the above values.

[0120] In some embodiments, the mass percentage of the second adhesive is N4, based on the mass of the fourth coating, where 1% ≤ N4 ≤ 20%.

[0121] In some embodiments, the mass percentage of the second adhesive is N4 based on the mass of the fourth coating. N4 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, or fall within the range of any two of the above values.

[0122] In some embodiments, the mass percentage of the second inorganic particles is K4, based on the mass of the fourth coating, where 60% ≤ K4 ≤ 98%.

[0123] In some embodiments, the mass percentage of the second inorganic particles is K4 based on the mass of the fourth coating. K4 can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, or 98%, or fall within the range of any two of the above values.

[0124] In some embodiments, the mass percentage of the second conductive agent is D4, based on the mass of the fourth coating, where 1% ≤ D4 ≤ 20%.

[0125] In some embodiments, the mass percentage of the second conductive agent is D4 based on the mass of the fourth coating. D4 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, or fall within the range of any two of the above values.

[0126] In some embodiments, in the first coating and / or the third coating, the first adhesive includes at least one of an acrylic polymer, polyurethane, polyvinyl alcohol (PVA), a polyvinyl alcohol derivative, and polyimide.

[0127] In some embodiments, the acrylic-containing polymer includes polyacrylic acid.

[0128] In some embodiments, the first inorganic particles in the first coating and / or the third coating include at least one of alumina, silicon dioxide, titanium dioxide, boehmite, boron nitride, and silicon carbide.

[0129] In some embodiments, the average particle size Dv50 of the first inorganic particles in the first coating and / or the third coating is 50-800 nm.

[0130] In some embodiments, in the first coating and / or the third coating, the average particle size Dv50 of the first inorganic particles is 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm or 800nm, or falls within the range of any two of the above values.

[0131] In some embodiments, the first conductive agent in the first coating and / or the third coating includes at least one of carbon, carbon black, graphite, expanded graphite, graphene, acetylene black, Ketjen black, carbon fiber, graphitized carbon sheet, and carbon nanotube.

[0132] In some embodiments, in the second coating and / or the fourth coating, the second adhesive comprises at least one of an acrylic polymer, polyurethane, polyvinyl alcohol (PVA), a polyvinyl alcohol derivative, and polyimide.

[0133] In some embodiments, the acrylic-containing polymer includes polyacrylic acid.

[0134] In some embodiments, the second inorganic particles in the second coating and / or the fourth coating include at least one of alumina, silicon dioxide, titanium dioxide, boehmite, boron nitride, and silicon carbide.

[0135] In some embodiments, the average particle size Dv50 of the second inorganic particles in the second coating and / or the fourth coating is 50-800 nm.

[0136] In some embodiments, in the second coating and / or the fourth coating, the average particle size Dv50 of the second inorganic particles is 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm or 800nm, or falls within the range of any two of the above values.

[0137] In some embodiments, the second conductive agent in the second coating and / or the fourth coating includes at least one of carbon, carbon black, graphite, expanded graphite, graphene, acetylene black, Ketjen black, carbon fiber, graphitized carbon sheet, and carbon nanotube.

[0138] In some embodiments, the first adhesive and the second adhesive are the same or similar.

[0139] In this application, when the first adhesive and the second adhesive are the same or similar, a stronger chemical bond and physical interweaving will be formed between the first coating and the second coating, and between the third coating and the fourth coating. This is more conducive to interfacial adhesion and allows the first, second, third and fourth coatings to play their respective roles better. This is beneficial to further suppress the generation of cracks in the electrochemical device during charge and discharge cycles, thereby improving the cycle life of the electrochemical device.

[0140] In some embodiments, along the electrode winding direction, the first coating perpendicular to the first center line of the length direction, the second coating perpendicular to the second center line of the length direction, the third coating perpendicular to the third center line of the length direction, and the fourth coating perpendicular to the fourth center line of the length direction coincide with each other.

[0141] In some embodiments, the first active material layer and / or the second active material layer include at least one of an active material, a conductive agent, and a binder.

[0142] In some embodiments, the active material includes a positive electrode active material and / or a negative electrode active material.

[0143] In some embodiments, the positive electrode active material can be selected from LiCoO2, LiNiO2, LiNi x Mn y O2, Li 1+z Ni x Mn y Co 1-x-y O2, LiNi x Co y Al zThe group consisting of O2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, Li2MnO3, LiFeO2, LiFePO4, LiMnPO4, and combinations thereof, wherein each x is independently 0.2 to 0.9; each y is independently 0.1 to 0.45; and each z is independently 0 to 0.2. The positive electrode active material of this application is not limited to the above-mentioned materials, but also includes other materials that can be used as positive electrode active materials.

[0144] In some embodiments, the negative electrode active material may include natural graphite, synthetic graphite, hard carbon, soft carbon, mesophase carbon microspheres (MCMB), Sn, SnO2, SnO, Li4Ti5O 12 The negative electrode active material is selected from at least one of the following: LTO, Si material, silicon-carbon (Si-C) composite material, silicon-nitrogen (Si-N) composite material, and silicon-oxygen (Si-O) composite material. The negative electrode active material of this application is not limited to the above-mentioned materials, but also includes other materials that can be used as negative electrode active materials for batteries.

[0145] In some embodiments, the conductive agent includes a positive conductive agent and / or a negative conductive agent.

[0146] In some embodiments, the positive electrode conductive agent may include at least one selected from carbon, carbon black, graphite, expanded graphite, graphene, acetylene black, Ketjen black, carbon fiber, graphitized carbon sheet, and carbon nanotubes. The positive electrode conductive agent in this application is not limited to the above materials, but also includes other materials that can be used as positive electrode conductive agents in batteries.

[0147] In some embodiments, the negative electrode conductive agent may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, acetylene black, Ketjen black, carbon fiber, graphitized carbon sheet, and carbon nanotubes. The negative electrode conductive agent of this application is not limited to the above materials, but also includes other materials that can be used as battery negative electrode conductive agents.

[0148] In some embodiments, the adhesive may include a positive electrode adhesive and / or a negative electrode adhesive.

[0149] In some embodiments, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyacrylic acid, polyacrylonitrile, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone (PVP), acrylic acid-acrylonitrile-acrylamide copolymer, and acrylic acid-acrylonitrile-acrylate copolymer. The positive electrode binder of this application is not limited to the above materials, but also includes other materials that can be used as battery positive electrode binders.

[0150] In some embodiments, the negative electrode binder may include at least one of polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, polyacrylamide, styrene-butadiene rubber, acrylic styrene-butadiene rubber, acrylic acid-acrylonitrile-acrylamide copolymer, acrylic acid-acrylonitrile-acrylate copolymer, acrylonitrile-butadiene rubber, nitrile rubber, acrylonitrile-styrene-butadiene copolymer, acryloyl rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyvinyl alcohol, polyvinyl acetate, polyepoxychloropropane, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, carboxymethyl chitosan, polyester, polyamide, polyether, polyimide, polycarboxylic acid ester, polycarboxylic acid, polyurethane, alginate, fluorinated polymer, chlorinated polymer, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropylene. The negative electrode binder of this application is not limited to the above-mentioned materials, but also includes other materials that can be used as battery negative electrode binders.

[0151] In some embodiments, the current collector includes a positive current collector and / or a negative current collector.

[0152] In some embodiments, the positive current collector is a metal foil or a composite current collector. In some embodiments, the metal foil is aluminum foil. The composite current collector may include a metal foil substrate and a conductive layer disposed on at least one side of the metal foil substrate. In some embodiments, the conductive layer may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon nanotubes, activated carbon, and mesoporous carbon.

[0153] In some embodiments, the negative current collector is a metal foil or a composite current collector. In some embodiments, the metal foil is a copper foil. The composite current collector may include a metal foil substrate and a conductive layer disposed on at least one side of the metal foil substrate. In some embodiments, the conductive layer may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon nanotubes, activated carbon, and mesoporous carbon.

[0154] II. Electrochemical Device This application provides an electrochemical device including the electrode described above.

[0155] In some embodiments, the electrochemical device also includes a diaphragm and an electrolyte.

[0156] 1. Diaphragm This application does not impose any particular limitation on the diaphragm, as long as it can achieve the purpose of this application. The diaphragm used in this application can be any diaphragm known in the prior art. For example, the type of diaphragm can include, but is not limited to, at least one of woven membranes, nonwoven membranes, microporous membranes, composite membranes, rolled membranes, and spun membranes. The material of the diaphragm can include, but is not limited to, at least one of polyethylene (PE), polyolefins (PO) mainly composed of polypropylene (PP), polyester, cellulose, polyimide (PI), polyamide (PA), spandex, and aramid. Polyester can include, but is not limited to, polyethylene terephthalate (PET) film.

[0157] In some embodiments, the diaphragm includes a substrate layer. The substrate layer may include, but is not limited to, at least one of a nonwoven fabric, membrane, or composite membrane having a porous structure. The material of the substrate layer may include, but is not limited to, at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. In some embodiments, the substrate layer may include, but is not limited to, at least one of a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane.

[0158] In some embodiments, the diaphragm further includes a surface treatment layer disposed on at least one surface of the substrate layer. The surface treatment layer may include, but is not limited to, at least one of a polymer layer, an inorganic layer, and a layer formed by a mixture of polymers and inorganic substances. The polymer layer includes polymers. This application does not particularly limit the polymer, as long as it achieves the purpose of this application. For example, the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymers, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, and poly(vinylidene fluoride-hexafluoropropylene). The inorganic layer includes inorganic particles and a binder. This application does not particularly limit the inorganic particles and binder, as long as they achieve the purpose of this application. For example, the inorganic particles may include, but are not limited to, at least one of alumina, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. For example, the adhesive may include, but is not limited to, at least one of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyacrylic acid, polyacrylonitrile, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone (PVP), acrylic acid-acrylonitrile-acrylamide copolymer, and acrylic acid-acrylonitrile-acrylate copolymer.

[0159] In some embodiments, the present application does not have a particular limitation on the thickness of the diaphragm, as long as the purpose of the present application can be achieved. For example, the thickness of the diaphragm is from 1 μm to 500 μm.

[0160] 2. Electrolytes In some embodiments, the electrolyte may include at least one of a gel electrolyte, a solid electrolyte, and a liquid electrolyte.

[0161] In some embodiments, the liquid electrolyte may include a non-aqueous solvent and a lithium salt.

[0162] In some embodiments, the lithium salt may include at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, LiBOB, and lithium difluoroborate.

[0163] In some embodiments, the non-aqueous solvent may be at least one of carbonate compounds, carboxylic acid ester compounds, and ether compounds.

[0164] In some embodiments, the carbonate compound may include at least one of chain carbonate compounds, cyclic carbonate compounds, and fluorocarbonate compounds.

[0165] In some embodiments, the chain carbonate compound may include at least one of diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), and methyl ethyl carbonate (MEC).

[0166] In some embodiments, the cyclic carbonate compound may include at least one of ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), vinyl ethylene carbonate (VEC), and vinylene carbonate (VC).

[0167] In some embodiments, the fluorocarbonate compound may include at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, and trifluoromethylethylene carbonate.

[0168] In some embodiments, the carboxylic acid ester compound may include at least one of methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate (PP), γ-butyrolactone, decanoic acid lactone, valerate lactone, mevalonate lactone, caprolactone, and methyl formate.

[0169] In some embodiments, the ether compound may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran.

[0170] In some embodiments, the non-aqueous solvent may also include at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolium ketone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters.

[0171] III. Electrochemical Device This application also provides an electronic device that includes the electrochemical device described above.

[0172] The electronic device described in this application is not particularly limited and can be any electronic device known in the prior art. The electrochemical device described in this application is also not particularly limited in its use and can be used in any electronic device known in the prior art. According to some embodiments of this application, the electronic device includes, but is not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, robot dogs, industrial robots, and android robots.

[0173] IV. Testing Methods 1. Test of the average particle size Dv50 of the first inorganic particles Disassemble the lithium-ion secondary battery, remove the electrode (positive electrode), and cut it along the thickness direction to obtain a flat cross-section. Randomly select at least 5 test areas in the first or third coating region of the cross-section, and then observe the test areas at 1000x magnification using a scanning electron microscope (SEM). Measure the average particle size Dv50 of the first inorganic particles in the test areas, and then calculate the arithmetic mean of at least 5 test areas, which is the average particle size Dv50 of the first inorganic particles in the first or third coating.

[0174] 2. Test of the average particle size Dv50 of the second inorganic particles Disassemble the lithium-ion secondary battery, remove the electrode (positive electrode), and cut it along the thickness direction to obtain a flat cross-section. Randomly select at least 5 test areas in the second or fourth coating region of the cross-section, and then observe the test areas at 1000x magnification using a scanning electron microscope (SEM). Measure the average particle size Dv50 of the second inorganic particles in the test areas, and then calculate the arithmetic mean of at least 5 test areas, which is the average particle size Dv50 of the second inorganic particles in the second or fourth coating.

[0175] 3. Fragmentation test In a 25°C environment, the lithium-ion secondary battery is charged to 4.55V at a constant current and constant voltage of 0.5C, with a cutoff current of 0.05C. Then, it is discharged to 3.0V at a constant current of 0.5C. This constitutes one charge-discharge cycle. This charge-discharge cycle is repeated multiple times until the capacity retention rate of the lithium-ion secondary battery drops to 80%. The test is then stopped, and the lithium-ion secondary battery is scanned using a commercial CT scanner to observe whether there are cracks or breaks in the positive electrode. If the positive electrode has cracks and / or breaks, it is considered to be a broken electrode.

[0176] 4. Cyclic life test In a 25℃ environment, the lithium-ion secondary battery is charged to 4.55V at a constant current and constant voltage of 0.5C, with a cutoff current of 0.05C, and then discharged to 3.0V at a constant current of 0.5C. This constitutes one charge-discharge cycle. This charge-discharge cycle is repeated multiple times until the capacity retention rate of the lithium-ion secondary battery drops to 80%. The test is then stopped, and the number of charge-discharge cycles at this point is recorded as the cycle number. The higher the number of cycles, the longer the cycle life of the lithium-ion rechargeable battery.

[0177] V. Examples It should be noted that, in the specific embodiments of this application, lithium-ion secondary batteries are used as an example of electrochemical devices to explain this application, but the electrochemical devices of this application are not limited to lithium-ion secondary batteries.

[0178] Unless otherwise specified, all reagents, materials, and instruments used in the following examples and comparative examples are commercially available. Furthermore, unless otherwise specified, "parts" and "%" refer to mass measurements.

[0179] In the following examples and comparative examples, the use of some reagents and materials is as follows: Polyurethane is supplied via waterborne polyurethane (W909579, McLean) with a solid content of 60%. When using polyurethane, the amount of waterborne polyurethane can be weighed according to the actual amount of polyurethane required. Polyacrylic acid, P815683, McLean; Kochen Black, K698346, McLean; Silica with an average particle size Dv50=500nm is obtained by grinding and crushing 40-60μm silica of the M697770 type produced by McLean and then sieving it. Packaging bags, aluminum-plastic film, E103, Shanghai Zijang New Material Technology Co., Ltd.; Polyvinylidene fluoride (PVDF), 768739, McLean; Ethylene carbonate (EC), CAS No.: 96-49-1; Diethyl carbonate (DEC), CAS No.: 105-58-8; Propylene carbonate (PC), CAS No.: 108-32-7; Propyl propionate (PP), CAS No.: 106-36-5; Vinyl carbonate (VC), CAS No.: 872-36-6.

[0180] Example 1 This embodiment provides an electrode (positive electrode), the structural schematic of which is shown below. Figure 1As shown, the electrode includes a positive current collector 7 (aluminum foil), and the positive current collector 7 (aluminum foil) includes a first surface and a second surface disposed opposite to each other; The first surface is provided with a first active material layer 5 and a first reinforcing coating. The first reinforcing coating includes a first coating 1 and a second coating 2. The first coating 1 is located between the positive current collector 7 (aluminum foil) and the second coating 2. At least a portion of the first active material layer 5 is provided on the surface of a portion of the first reinforcing coating. The second surface is provided with a second active material layer 6 and a second reinforcing coating. The second reinforcing coating includes a third coating 3 and a fourth coating 4. The third coating 3 is located between the positive current collector 7 (aluminum foil) and the fourth coating 4. The surface of the second reinforcing coating is provided with at least a portion of the second active material layer 6. The first coating 1 and the third coating 3 each independently include a first binder (polyurethane), a first conductive agent (Ketjen black), and a first inorganic particle (silicon dioxide), and the second coating 2 and the fourth coating 4 each independently include a second inorganic particle (silicon dioxide), a second binder (polyurethane), and a second conductive agent (Ketjen black). Along the electrode winding direction, the distance between the tail end of the first active material layer 5 and the tail end of the electrode is greater than the distance between the tail end of the second active material layer 6 and the tail end of the electrode; the area where the orthographic projection of the second active material layer 6 on the electrode coincides with the orthographic projection of the first active material layer 5 on the electrode is a double-sided coating area, and the rest is a single-sided coating area; the beginning and end ends of the first coating 1 and the second coating 2 do not coincide, and the beginning and end ends of the third coating 3 and the fourth coating 4 do not coincide; the length of the first coating 1 is L1 mm, L1=13; the length of the second coating 2 is L2 mm, L2=8; the length of the third coating 3 is L3 mm, L3=27; and the length of the fourth coating 4 is L4 mm, L4=22. L1, L2, L3, and L4 satisfy: L1 > L2 > 0; L3 > L4 > 0; L3 > L1; L3 + L4 - L1 - L2 = 28; The height of the first coating 1 is H1 μm, H1=0.2; the height of the second coating 2 is H2 μm, H2=4; the height of the third coating 3 is H3 μm, H3=0.2; and the height of the fourth coating 4 is H4 μm, H4=4. H1, H2, H3, and H4 satisfy the following: H2 / H1=20; H4 / H3=20; H3 + H4 - H1 - H2 = 0; Based on the mass of the first coating 1, the mass percentage of the first adhesive (polyurethane) is N1, N1=75%, the mass percentage of the first inorganic particles (silicon dioxide) is K1, K1=5%, and the mass percentage of the first conductive agent (Ketjen Black) is D1, D1=20%. Based on the mass of the second coating 2, the mass percentage of the second adhesive (polyurethane) is N2, N2=10%, the mass percentage of the second inorganic particles (silicon dioxide) is K2, K2=80%, and the mass percentage of the second conductive agent (Ketjen Black) is D2, D2=10%. Based on the mass of the third coating 3, the mass percentage of the first adhesive (polyurethane) is N3, N3=75%, the mass percentage of the first inorganic particles (silicon dioxide) is K3, K3=5%, and the mass percentage of the first conductive agent (Ketjen Black) is D3, D3=20%. Based on the mass of the fourth coating 4, the mass percentage of the second adhesive (polyurethane) is N4, N4 = 10%, the mass percentage of the second inorganic particles (silicon dioxide) is K4, K4 = 80%, and the mass percentage of the second conductive agent (Ketjen Black) is D4, D4 = 10%. Along the electrode winding direction, the first coating 1 perpendicular to the first center line of the length direction, the second coating 2 perpendicular to the second center line of the length direction, the third coating 3 perpendicular to the third center line of the length direction, and the fourth coating 4 perpendicular to the fourth center line of the length direction overlap with each other. The first active material layer 5 includes a positive electrode active material (lithium cobalt oxide, LiCoO2), a positive electrode conductive agent (Ketjen Black), and a positive electrode binder (polyvinylidene fluoride, PVDF). The second active material layer 6 includes a positive electrode active material (lithium cobalt oxide, LiCoO2), a positive electrode conductive agent (Ketjen black), and a positive electrode binder (polyvinylidene fluoride, PVDF). This embodiment also provides a lithium-ion secondary battery (electrochemical device), the preparation method of which includes the following steps: 1. Preparation of positive electrode sheet (1) Mix the first binder (polyurethane), the first inorganic particles (silica) and the first conductive agent (Ketjen black) in a mass ratio of 75:5:20 to obtain the first coating mixture; mix the first coating mixture with the solvent deionized water to obtain the first coating slurry with a solid content of 15%wt, for later use. (2) Mix the second binder (polyurethane), the second inorganic particles (silica), and the second conductive agent (Ketjen black) in a mass ratio of 10:80:10 to obtain the second coating mixture; mix the second coating mixture with the solvent deionized water to obtain a second coating slurry with a solid content of 20%wt, for later use. (3) Mix the first binder (polyurethane), the first inorganic particles (silica) and the first conductive agent (Ketjen black) in a mass ratio of 75:5:20 to obtain the third coating mixture; mix the third coating mixture with the solvent deionized water to obtain a third coating slurry with a solid content of 15%wt, for later use. (4) Mix the second binder (polyurethane), the second inorganic particles (silica), and the second conductive agent (Ketjen black) in a mass ratio of 10:80:10 to obtain the fourth coating mixture; mix the fourth coating mixture with the solvent deionized water to obtain the fourth coating slurry with a solid content of 20%wt, for later use. (5) The positive electrode active material (lithium cobalt oxide, LiCoO2), positive electrode conductive agent (Ketjen black), and positive electrode binder (polyvinylidene fluoride, PVDF) are mixed in a mass ratio of 98:1.2:0.8. N-methylpyrrolidone (NMP) is added and stirred evenly under the action of a vacuum mixer to obtain a positive electrode active material slurry with a solid content of 70wt%, which is ready for use. (6) Figure 1 As shown, aluminum foil (9μm) is used as the positive electrode current collector. A first coating slurry is first coated on one surface of the positive electrode current collector and dried to obtain the first coating. A second coating slurry is then coated on the surface of the first coating and dried to obtain the second coating. Next, a third coating slurry is first coated on the other surface of the positive electrode current collector and dried to obtain the third coating. A fourth coating slurry is then coated on the surface of the third coating and dried to obtain the fourth coating. Then, a positive electrode active material layer slurry is coated on both sides of the positive electrode current collector and dried to obtain the first active material layer and the second active material layer. Finally, the positive electrode sheet is obtained after rolling and cutting. The thickness of the first active material layer is 45μm, and the thickness of the second active material layer is 45μm. 2. Preparation of negative electrode sheet The negative electrode active material (natural graphite), negative electrode conductive agent (acetylene black, SP), negative electrode binder (styrene-butadiene rubber), and thickener (sodium carboxymethyl cellulose) were thoroughly mixed in deionized water at a mass ratio of 98.1:0.5:0.7:0.7 to obtain a negative electrode active material slurry with a solid content of 40wt%. Under vacuum at 105℃, the negative electrode active material slurry was continuously coated onto the negative electrode current collector copper foil. After drying, rolling, and cutting, a negative electrode sheet with negative electrode active material layers on both sides was obtained, wherein the thickness of the negative electrode active material layer on one side was 40μm. 3. Preparation of electrolyte In a dry argon atmosphere glove box, ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), propyl propionate (PP), and vinylene carbonate (VC) were mixed in a mass ratio of EC:DEC:PC:PP:VC = 25:25:15:31:4 to obtain a non-aqueous solvent. Then, lithium salt LiPF6 was added to dissolve and mix thoroughly to obtain an electrolyte; wherein the mass concentration of LiPF6 in the electrolyte was 8%.

[0181] 4. Preparation of lithium-ion secondary batteries (electrochemical devices) The positive electrode, separator (5μm porous polyethylene membrane), and negative electrode prepared above are stacked in sequence and wound to obtain an electrode assembly. The electrode assembly is placed in a packaging bag (aluminum-plastic film), dried, and then injected with electrolyte. After vacuum sealing, settling, formation, degassing, and edge trimming, a lithium-ion secondary battery is obtained.

[0182] Examples 2-7 and Comparative Examples 1-9 Examples 2-7 and Comparative Examples 1-9 differ from Example 1 in that the values ​​of L1, L2, L3, and L4 are different, as shown in Table 1. All other values ​​are the same as in Example 1. The values ​​of L1, L2, L3, and L4 are obtained by adjusting the coating lengths of the first, second, third, and fourth coatings, as shown in Table 1.

[0183] Examples 8-13 Examples 8-13 differ from Example 1 in that the values ​​of H1, H2, H3, H4, H2 / H1, and H4 / H3 are different, as shown in Table 2. All other values ​​are the same as in Example 1. The coating thicknesses of the first, second, third, and fourth coatings were adjusted to achieve the values ​​of H1, H2, H3, H4, H2 / H1, and H4 / H3, as shown in Table 2.

[0184] Examples 14-17 Examples 14-17 differ from Example 1 in that the values ​​of H1, H2, H3, H4, and H3+H4-H1-H2 are different, as shown in Table 3. All other values ​​are the same as in Example 1. The coating thicknesses of the first, second, third, and fourth coatings were adjusted to achieve the values ​​of H1, H2, H3, H4, and H3+H4-H1-H2 as shown in Table 3.

[0185] Examples 18-23 Examples 18-23 differ from Example 1 in that the values ​​of N1, K1, D1, N3, K3, and D3 are different, as shown in Table 4. All other values ​​are the same as in Example 1. N1, K1, and D1 are adjusted as shown in Table 4 by controlling the amounts of the first binder, first inorganic particles, and first conductive agent in the first coating. N3, K3, and D3 are adjusted as shown in Table 4 by controlling the amounts of the first binder, first inorganic particles, and first conductive agent in the third coating.

[0186] Examples 24-26 Examples 24-26 differ from Example 1 in that the values ​​of N2, K2, D2, N4, K4, and D4 are different, as shown in Table 5; all other values ​​are the same as in Example 1. The values ​​of N2, K2, and D2 in the second coating are adjusted by controlling the amounts of the second binder, second inorganic particles, and second conductive agent, as shown in Table 5. The values ​​of N4, K4, and D4 in the fourth coating are adjusted by controlling the amounts of the second binder, second inorganic particles, and second conductive agent, as shown in Table 5.

[0187] Example 27 The difference between Example 27 and Example 1 is that the first adhesive in the first coating and the third coating is replaced with polyacrylic acid instead of polyurethane, while the rest is the same as in Example 1.

[0188] Comparative Example 10 like Figure 2 As shown, the difference between Comparative Example 10 and Example 1 is that: (1) The first ends of the first coating 1 and the second coating 2 coincide, and the first ends of the third coating 3 and the fourth coating 4 coincide; (2) Along the electrode winding direction, the first coating 1 perpendicular to the first center line of the length direction, the second coating 2 perpendicular to the second center line of the length direction, the third coating 3 perpendicular to the third center line of the length direction, and the fourth coating 4 perpendicular to the fourth center line of the length direction do not overlap with each other. Everything else is the same as in Example 1.

[0189] Table 1. Condition parameters and performance test results for Examples 1-7 and Comparative Examples 1-9 As shown in Table 1, the electrode of this application can suppress the generation of cracks in the electrochemical device during charge-discharge cycles, and can also improve the cycle life of the electrochemical device.

[0190] Table 2. Condition parameters and performance test results for Examples 1 and 8-13 As shown in Table 2, the electrode of this application can suppress the generation of cracks in the electrochemical device during charge-discharge cycles, and can also improve the cycle life of the electrochemical device.

[0191] Table 3. Condition parameters and performance test results of Examples 14-17 As shown in Table 3, the electrode of this application can suppress the generation of cracks in the electrochemical device during charge-discharge cycles, and can also improve the cycle life of the electrochemical device.

[0192] Table 4. Condition parameters and performance test results for Examples 1, 18-23 As shown in Table 4, the electrode of this application can suppress the generation of cracks in the electrochemical device during charge-discharge cycles, and can also improve the cycle life of the electrochemical device.

[0193] Table 5. Condition parameters and performance test results for Examples 1 and 24-26 As shown in Table 5, the electrode of this application can suppress the generation of cracks in the electrochemical device during charge-discharge cycles, and can also improve the cycle life of the electrochemical device.

[0194] Table 6. Condition parameters and performance test results of Examples 1 and 27 and Comparative Example 10. As shown in Table 6, the electrode of this application can suppress the generation of cracks in the electrochemical device during charge-discharge cycles, and can also improve the cycle life of the electrochemical device.

[0195] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. An electrode sheet, characterized in that, The electrode includes a current collector, which includes a first surface and a second surface disposed opposite to each other. The first surface is provided with a first active material layer and a first reinforcing coating. The first reinforcing coating includes a first coating and a second coating. The first coating is located between the current collector and the second coating. At least a portion of the first active material layer is provided on the surface of a portion of the first reinforcing coating. The second surface is provided with a second active material layer and a second reinforcing coating. The second reinforcing coating includes a third coating and a fourth coating. The third coating is located between the current collector and the fourth coating. The surface of the second reinforcing coating is provided with at least a portion of the second active material layer. The first coating and the third coating each independently include a first binder and a first conductive agent, and the second coating and the fourth coating each independently include second inorganic particles, a second binder and a second conductive agent; Along the electrode winding direction, the distance between the tail end of the first active material layer and the tail end of the electrode is greater than the distance between the tail end of the second active material layer and the tail end of the electrode; the area where the orthographic projection of the second active material layer on the electrode coincides with the orthographic projection of the first active material layer on the electrode is the double-sided coating area, and the rest is the single-sided coating area; the beginning and end ends of the first coating layer and the second coating layer do not coincide, and the beginning and end ends of the third coating layer and the fourth coating layer do not coincide; the length of the first coating layer is L1 mm, the length of the second coating layer is L2 mm, the length of the third coating layer is L3 mm, and the length of the fourth coating layer is L4 mm, where L1, L2, L3, and L4 satisfy: L1 > L2 > 0; L3 > L4 > 0; L3 > L1; 5≤L3+L4-L1-L2≤51.

2. The electrode as described in claim 1, characterized in that, Satisfy at least one of the following (1)-(5): (1)5≤L1≤26； (2)3≤L2≤24； (3)7≤L3≤30； (4)6≤L4≤29； (5)20≤L3+L4-L1-L2≤35.

3. The electrode as described in claim 1, characterized in that, The height of the first coating is H1 μm, the height of the second coating is H2 μm, the height of the third coating is H3 μm, and the height of the fourth coating is H4 μm, wherein H1, H2, H3, and H4 satisfy the following: 0.2≤H2 / H1≤40; 0.2≤H4 / H3≤40.

4. The electrode as described in claim 3, characterized in that, Satisfy at least one of the following (1)-(3): (1) 10 ≤ H2 / H1 ≤ 30; (2) 10 ≤ H4 / H3 ≤ 30; (3)H3+H4-H1-H2≥0.

5. The electrode sheet as described in claim 3, characterized in that, Satisfy at least one of the following (1)-(4): (1)0.2≤H1≤5； (2)1≤H2≤8； (3)0.2≤H3≤5； (4)1≤H4≤8。 6. The electrode as described in claim 1, characterized in that, Satisfy at least one of the following (1)-(12): (1) Based on the mass of the first coating, the mass percentage of the first adhesive is N1, where 60% ≤ N1 ≤ 90%; (2) The first coating also includes first inorganic particles; (3) Based on the mass of the first coating, the mass percentage of the first conductive agent is D1, where 1% ≤ D1 ≤ 40%; (4) Based on the mass of the second coating, the mass percentage of the second adhesive is N2, where 1% ≤ N2 ≤ 20%; (5) Based on the mass of the second coating, the mass percentage of the second inorganic particles is K2, 60%≤K2≤98%; (6) Based on the mass of the second coating, the mass percentage of the second conductive agent is D2, where 1% ≤ D2 ≤ 20%; (7) Based on the mass of the third coating, the mass percentage of the first adhesive is N3, where 60% ≤ N3 ≤ 90%; (8) The third coating also includes first inorganic particles; (9) Based on the mass of the third coating, the mass percentage of the first conductive agent is D3, where 1% ≤ D3 ≤ 40%; (10) Based on the mass of the fourth coating, the mass percentage of the second adhesive is N4, where 1% ≤ N4 ≤ 20%; (11) Based on the mass of the fourth coating, the mass percentage of the second inorganic particles is K4, 60%≤K4≤98%; (12) Based on the mass of the fourth coating, the mass percentage of the second conductive agent is D4, where 1% ≤ D4 ≤ 20%.

7. The electrode sheet as described in claim 6, characterized in that, Satisfy at least one of the following (1)-(3): (1) Based on the mass of the first coating, the mass percentage of the first inorganic particles is K1, where 0%≤K1≤10%; (2) Based on the mass of the third coating, the mass percentage of the first inorganic particles is K3, where 0%≤K3≤10%; (3) In the first coating and / or the third coating, the first inorganic particles include at least one of alumina, silicon dioxide, titanium dioxide, boehmite, boron nitride, and silicon carbide.

8. The electrode sheet as described in claim 1, characterized in that, Satisfy at least one of the following (1)-(7): (1) In the first coating and / or the third coating, the first adhesive includes at least one of acrylic polymer, polyurethane, polyvinyl alcohol, polyvinyl alcohol derivative, and polyimide; (2) In the first coating and / or the third coating, the first conductive agent includes at least one of carbon, carbon black, graphite, expanded graphite, graphene, acetylene black, Ketjen black, carbon fiber, graphitized carbon sheet, and carbon nanotube. (3) In the second coating and / or the fourth coating, the second adhesive includes at least one of acrylic polymer, polyurethane, polyvinyl alcohol, polyvinyl alcohol derivative, and polyimide; (4) In the second coating and / or the fourth coating, the second inorganic particles include at least one of alumina, silicon dioxide, titanium dioxide, boehmite, boron nitride, and silicon carbide; (5) In the second coating and / or the fourth coating, the second conductive agent includes at least one of carbon, carbon black, graphite, expanded graphite, graphene, acetylene black, Ketjen black, carbon fiber, graphitized carbon sheet, and carbon nanotube. (6) The first adhesive and the second adhesive are the same or similar; (7) Along the electrode winding direction, the first coating perpendicular to the first center line of the length direction, the second coating perpendicular to the second center line of the length direction, the third coating perpendicular to the third center line of the length direction, and the fourth coating perpendicular to the fourth center line of the length direction coincide with each other.

9. An electrochemical device, characterized in that, Includes the electrode as described in any one of claims 1-8.

10. An electronic device, characterized in that, Includes the electrochemical device as described in claim 9.

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