Electrode plate, electrochemical device and electronic device comprising same

Abstract

The invention relates to an electrode plate, an electrochemical device and an electronic device comprising the same. The electrode plate comprises a current collector, a first active material layer, a second active material layer and an insulating layer. The current collector includes a first surface, the first active material layer includes a first active material, and the second active material layer includes a second active material. The first active material layer is arranged between the current collector and the second active material layer and covers a first part of a first surface of the current collector, the insulating layer covers a second part, different from the first part, of the first surface of the current collector, and the first active material layer comprises a first end and a second end in the length direction of the electrode pole piece; the insulating layer comprises a third end and a fourth end, and the insulating layer and the first active material layer are at least partially contacted. The current collector of the electrode plate can be covered by a layer with high resistivity, and the safety performance of an electrochemical device and an electronic device is improved.

Description

[0001] This application is a divisional application with application number 202010253819.4, application date April 2, 2020, and invention name “Electrode plate, electrochemical device and electronic device containing the same”. Technical Field

[0002] The present application relates to the field of energy storage technology, and in particular to an electrode plate, an electrochemical device, and an electronic device including the electrochemical device. Background Art

[0003] Electrochemical devices (e.g., lithium-ion batteries) have entered our daily lives with the advancement of technology and the improvement of environmental protection requirements. With the widespread popularity of lithium-ion batteries, safety issues caused by external force puncturing lithium-ion batteries occasionally occur at the user end. Its safety performance has received more and more attention, especially the continued fermentation of some mobile phone explosion incidents, which has led to new requirements for the safety performance of lithium-ion batteries by users, after-sales service and lithium-ion battery manufacturers.

[0004] At present, the methods for improving the safety performance of lithium-ion batteries, such as increasing the binder content in the positive electrode active material layer and thickening the ceramic coating on the surface of the separator, are all at the expense of the energy density of the lithium-ion battery. Therefore, it is urgent to provide a technical means that can significantly improve the safety performance of lithium-ion batteries under the condition of higher energy density. Summary of the invention

[0005] The present application provides an electrode plate, an electrochemical device, and an electronic device including the electrochemical device in an attempt to solve at least one problem existing in the related art to at least some extent.

[0006] According to one aspect of the present application, some embodiments of the present application provide an electrode plate, which includes: a current collector, a first active material layer, a second active material layer and an insulating layer. The current collector includes a first surface, the first active material layer includes a first active material, and the second active material layer includes a second active material. The first active material layer is arranged between the current collector and the second active material layer and covers a first portion of the first surface of the current collector, and the insulating layer covers a second portion of the first surface of the current collector that is different from the first portion. In the length direction of the electrode plate, the first active material layer includes a first end and a second end, and the insulating layer includes a third end and a fourth end, and the first end and the third end are stacked on each other to form an overlapping portion.

[0007] According to one aspect of the present application, some embodiments of the present application provide an electrochemical device, which includes a positive electrode sheet, a separator and a negative electrode sheet, wherein the positive electrode sheet and / or the negative electrode sheet is the above-mentioned electrode sheet.

[0008] According to another aspect of the present application, some embodiments of the present application provide an electronic device, which includes the above-mentioned electrochemical device.

[0009] The electrochemical device of the present application adopts an electrode plate with a double active material layer structure, and an insulating layer is provided in the empty current collector portion not covered by the active material layer, and the current collector is completely covered by at least partially contacting the insulating layer with the first active material layer, thereby preventing short circuit between the electrode plates when the electrochemical device is impacted or punctured by external force, thereby improving the safety performance of the electrochemical device and the electronic device.

[0010] Additional aspects and other advantages of the embodiments of the present application will be described, shown, or explained in part in the subsequent description through implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following will briefly describe the drawings necessary for describing the embodiments of the present application or the prior art to facilitate the description of the embodiments of the present application. Obviously, the drawings described below are only some of the embodiments in the present application. For those skilled in the art, without the need for creative work, drawings of other embodiments can still be obtained based on the structures illustrated in these drawings.

[0012] Figure 1 It is a schematic diagram of the structure of an electrode plate in which an insulating layer covers a first active material layer in an embodiment of the present application.

[0013] Figure 2 It is a schematic diagram of the structure of an electrode electrode sheet in which an insulating layer covers a first active material layer in an embodiment of the present application (the second active material layer is flush with the edge of the current collector in the length direction).

[0014] Figure 3 It is a schematic diagram of the structure of an electrode electrode sheet in which an insulating layer covers a first active material layer in an embodiment of the present application (a second active material layer partially covers the overlapping portion).

[0015] Figure 4 It is a schematic diagram of the structure of an electrode pole piece in which a first active material layer covers an insulating layer in an embodiment of the present application.

[0016] Figure 5 It is a schematic diagram of the structure of an electrode pole piece in which the first active material layer covers the insulating layer in an embodiment of the present application (the second active material layer is flush with the edge of the current collector in the length direction).

[0017] Figure 6 It is a schematic diagram of the structure of an electrode electrode sheet in which the first active material layer covers the insulating layer in an embodiment of the present application (the second active material layer partially covers the overlapping part).

[0018] Figure 7It is a schematic diagram of the structure of the electrode plate of an embodiment of the present application (the structure of the active material layer on the second surface of the current collector).

[0019] Figure 8 Schematic diagram of the structure of the positive electrode plate of Example 1.

[0020] Fig. 9 This is a schematic diagram of the structure of the positive electrode plate of Example 7.

[0021] Fig.10 This is a schematic diagram of the structure of the positive electrode plate of Example 8.

[0022] Fig.11 This is a schematic diagram of the structure of the positive electrode plate of Example 9.

[0023] Fig.12 Schematic diagram of the structure of the positive electrode plate of Example 11.

[0024] Fig.13 This is a schematic diagram of the structure of the positive electrode plate of Example 12.

[0025] Fig.14 This is a schematic diagram of the structure of the positive electrode plate of Example 13. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in detail below. In the full text of the present application specification, the same or similar components and components with the same or similar functions are represented by similar reference numerals. The embodiments of the accompanying drawings described herein are illustrative and graphical and are used to provide a basic understanding of the present application. The embodiments of the present application should not be interpreted as limiting the present application.

[0027] In this specification, unless otherwise specified or limited, relative terms such as "central", "longitudinal", "lateral", "front", "rear", "right", "left", "inner", "outer", "lower", "higher", "horizontal", "vertical", "above", "below", "above", "below", "top", "bottom" and their derivative terms (such as "horizontally", "downwardly", "upwardly", etc.) should be interpreted as referring to the directions described in the discussion or depicted in the drawings. These relative terms are only used for convenience of description and do not require that the present application be constructed or operated in a specific direction.

[0028] In addition, sometimes amounts, ratios and other numerical values ​​are presented in range format herein. It should be understood that such range format is for convenience and brevity, and should be flexibly understood to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or sub-ranges encompassed within the range, as if each numerical value and sub-range were explicitly specified.

[0029] Furthermore, for ease of description, "first", "second", "third", etc. may be used herein to distinguish different components of one figure or a series of figures. Unless otherwise specifically specified or limited, "first", "second", "third", etc. are not intended to describe corresponding components.

[0030] In electrochemical devices (such as lithium-ion batteries), when impacted or punctured by external forces, four short-circuit modes usually occur: positive electrode active material layer-negative electrode active material layer, positive electrode active material layer-negative electrode current collector, positive electrode current collector-negative electrode current collector, positive electrode current collector-negative electrode active material layer. Among these four short-circuit modes, the short-circuit modes of positive electrode current collector-negative electrode active material layer and negative electrode current collector-positive electrode active material layer are the most dangerous of the four short-circuit modes, because the short-circuit power when these two short-circuit modes occur is relatively large.

[0031] The embodiment of the present application provides an electrode plate with a double active material layer structure, wherein a first active material layer and a second active material layer covering the first active material layer are arranged on the portion of the current collector covered by the active material layer, and an insulating layer is arranged on the empty current collector portion not covered by the first active material layer. The electrode plate adjusts the combination mode of the first active material layer and the insulating layer to form an overlapping portion, so that when the electrode plate is damaged by external force, the resistance of the current collector surface can be effectively increased, thereby improving the safety performance of the electrochemical device in the corresponding test (nail penetration or heavy object impact).

[0032] The electrochemical device includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. Both the positive electrode sheet and the negative electrode sheet include a current collector and an active material layer. Among them, in addition to the part covered by the active material layer, the current collector also includes a part not covered by the active material layer (also called an empty current collector part). For example, when the electrode assembly of the electrochemical device is a wound type, its empty current collector part includes the outer layer of the electrode assembly and the inner layer of the electrode assembly. The electrode tab welding part.

[0033] In the active material layer covering part, a double active material layer structure can be used to set the first active material layer at a position close to the current collector, and set the second active material layer at a position far from the current collector surface. The second active material layer can have a higher energy density than the first active material layer. When a collision or puncture occurs, the first active material layer can increase the contact resistance between the current collector and other contacts to protect the current collector. However, during the nail penetration test, the empty current collector part on the current collector will also directly contact the nail, thereby causing a possible short circuit. For example, the positive current collector can be connected to the negative active material layer through the nail, thereby forming a short circuit mode of the positive current collector-negative active material layer or the positive current collector-nail-negative active material layer. Therefore, by providing an insulating layer on the empty current collector area, the current collector in the electrode sheet can be effectively protected, thereby avoiding the short circuit mode of the positive current collector-negative active material layer or the negative current collector-positive active material layer, wherein the higher the coverage of the insulating layer on the empty current collector part of the current collector, the more obvious the effect of avoiding short circuit. The overlapping portion of the electrode plate of the present application can avoid exposure of the current collector at the junction of the insulating layer and the first active material layer through the mutual stacking and covering of the insulating layer and the first active material layer, thereby ensuring the coverage of the current collector by the insulating layer and improving the safety performance of the electrode plate.

[0034] Figure 1-3 Schematic diagram of the structure of the electrode sheet of some embodiments of the present application, wherein the insulating layer covers the first active material layer in the overlapping part of the electrode sheet. The electrode sheet can be a positive electrode sheet or a negative electrode sheet. Figure 1-3 As shown, the electrode plate includes a current collector 101, a first active material layer 102, a second active material layer 103 and an insulating layer 104. The first active material layer 102 is disposed between the current collector 101 and the second active material layer 103 and covers a first portion on one surface of the current collector 101, and the insulating layer 104 covers a second portion of the first surface of the current collector 101 that is different from the first portion. In the length direction of the electrode plate, the first active material layer 102 includes a first end 102a and a second end 102b, and the insulating layer 104 includes a third end 104b and a fourth end 104a, and the first end 102a and the third end 104b are stacked on each other to form an overlapping portion 105. There is no gap between the insulating layer 104 and the first active material layer 102 in the length direction of the electrode plate, so that the current collector 101 is not easily exposed when it is impacted or punctured by an external force.

[0035] In some embodiments, the distance between the edge of the first end 102a of the first active material layer 102 in the length direction of the electrode sheet and the edge of the third end 104b of the insulating layer 104 in the length direction of the electrode sheet in the length direction of the electrode sheet is less than or equal to 20 mm. That is, the length of the overlapping portion 105 of the first active material layer 102 and the insulating layer 104 in the length direction of the electrode sheet is less than or equal to 20 mm. In some embodiments, the length of the overlapping portion 105 of the first active material layer 102 and the insulating layer 104 in the length direction of the electrode sheet is 5.0 mm to 20 mm. In other embodiments, the length of the overlapping portion 105 of the first active material layer 102 and the insulating layer 104 in the length direction of the electrode sheet is approximately, for example, 0.5 mm, 1.0 mm, 2.5 mm, 5.0 mm, 10.0 mm, 15.0 mm, 20.0 mm, or a range consisting of any two of these values.

[0036] In some embodiments, Figure 1-3 As shown, in the thickness direction of the electrode sheet, the first end 102a is disposed between the third end 104b and the current collector 101. The process tolerance required to cover the third end 104b of the insulating layer 104 on the first end 102a of the first active material layer 102 in the overlapping portion 105 is low, which can reduce the time and cost required for manufacturing.

[0037] In some embodiments, in the length direction of the electrode sheet, the second active material layer includes a fifth end 103a, and the fifth end 103a is close to the overlapping portion 105. Figure 1 As shown, the second active material layer 103 can extend from the overlapping portion 105 in the length direction of the electrode sheet and cover a portion of the insulating layer 104, so that the edge of the first end 102a of the first active material layer 102 in the length direction of the electrode sheet is located between the edge of the third end 104b in the length direction of the electrode sheet and the edge of the fifth end 103a in the length direction of the electrode sheet.

[0038] In some embodiments, in the length direction of the electrode sheet, the distance between the edge of the first end 102a of the first active material layer 102 in the length direction of the electrode sheet and the edge of the fifth end 103a of the second active material layer 103 in the length direction of the electrode sheet is less than or equal to 3 mm. In some embodiments, the length of the extended portion of the second active material layer 103 covering the insulating layer 104 in the length direction of the electrode sheet is less than or equal to 3 mm.

[0039] In some embodiments, Figure 2 As shown, the edge of the fifth end 103 a of the second active material layer 103 in the length direction of the electrode sheet is flush with the edge of the third end 104 b of the insulating layer 104 in the length direction of the electrode sheet.

[0040] In some embodiments, Figure 3 As shown, the edge of the fifth end 103a of the second active material layer 103 in the length direction of the electrode sheet is located between the edge of the first end 102a of the first active material layer 102 in the length direction of the electrode sheet and the edge of the third end 104b of the insulating layer 104 in the length direction of the electrode sheet.

[0041] In some embodiments, the second active material layer 103 completely covers the first active material layer 102 except for the overlapping portion 105. Taking a lithium-ion battery as an example, the first active material layer 102 except for the overlapping portion 105 is exposed, which will cause the lithium ions in the exposed portion to escape, and there is no active material embedded with lithium ions on the corresponding electrode plate of the other polarity. The escaped lithium ions will form lithium metal particles on the current collector of the other polarity (for example, the negative electrode current collector), and the problem will continue to increase with the increase in the number of cycles of the lithium-ion battery, thereby causing lithium metal particle pitting on the surface of the negative electrode plate and reducing the capacity of the lithium-ion battery (electrochemical device).

[0042] In some embodiments, in the length direction of the electrode sheet, the length of the second active material layer 103 is greater than the length of the first active material layer 102 excluding the overlapping portion 105. In some embodiments, the length of the second active material layer 103 minus the length of the first active material layer 102 excluding the overlapping portion 105 is less than or equal to 4 mm.

[0043] Figure 4-6 is a schematic diagram of the structure of the electrode plates of some embodiments of the present application, wherein the insulating layer covers the first active material layer in the overlapping portion of the electrode plates. Figure 4-6 As shown, in the thickness direction of the electrode sheet, the third end 104b is disposed between the first end 102a and the current collector 101. Figure 4 As shown, the second active material layer 103 can extend from the overlapping portion 105 in the length direction of the electrode sheet and cover a portion of the insulating layer 104, so that the edge of the first end 102a of the first active material layer 102 in the length direction of the electrode sheet is located between the edge of the third end 104b in the length direction of the electrode sheet and the edge of the fifth end 103a in the length direction of the electrode sheet. Since the insulating effect of the insulating layer 104 is better than that of the first active material layer 102, when it is hit by a nail or a heavy object, such as Figure 4In the electrode plate shown, the insulating layer 104 covered by the first active material layer 102 in the overlapping portion 105 can better insulate the current collector 101, so it has a higher safety performance. At the same time, because the fifth end 103a of the second active material layer 103 covers the end of the first end 102a of the first active material layer 102, it is difficult for the first end 102a to fall off under a strong external force such as nail penetration or impact, so that the current collector 101 will not leak out, making its electrode assembly safer.

[0044] In some embodiments, Figure 5 As shown, the edge of the fifth end 103 a of the second active material layer 103 in the length direction of the electrode sheet is flush with the edge of the third end 104 b of the insulating layer 104 in the length direction of the electrode sheet.

[0045] In some embodiments, Figure 6 As shown, the edge of the fifth end 103a of the second active material layer 103 in the length direction of the electrode sheet is located between the edge of the first end 102a of the first active material layer 102 in the length direction of the electrode sheet and the edge of the third end 104b of the insulating layer 104 in the length direction of the electrode sheet.

[0046] Figure 7 1 is a schematic diagram of the structure of the electrode sheet of other embodiments of the present application, the electrode sheet further includes a third active material layer 106 and a fourth active material layer 107, and the current collector 101 further includes a second surface. The third active material layer 106 is disposed between the current collector 101 and the fourth active material layer 107 and covers the second surface of the current collector. In some embodiments, the third active material layer 106 has the same composition as the first active material layer 102, the fourth active material layer 107 has the same composition as the second active material layer 103, and the content of the active material in the third active material layer 106 is less than the content of the active material in the fourth active material layer 107.

[0047] like Figure 7 As shown, in some embodiments, in the length direction of the electrode plate, the third active material layer 106 includes a sixth end 106a, the sixth end 106a is close to the overlapping portion 105, and the edge of the sixth end 106a in the length direction of the electrode plate is located between the edge of the first end 102a in the length direction of the electrode plate and the edge of the fourth end 104a in the length direction of the electrode plate.

[0048] In some embodiments, in the length direction of the electrode sheet, the fourth active material layer 107 includes a seventh end 107a, the seventh end 107a is close to the overlapping portion 105, and the seventh end 107a exceeds the sixth end 106a in the length direction of the electrode sheet.

[0049] It should be understood that without violating the spirit of the present application, an insulating layer that overlaps with the active material layer can be provided at either end of the electrode plate according to actual needs. For example, an insulating layer can be provided at both ends of the two surfaces of the positive electrode collector (in the length direction of the positive electrode plate) where the empty current collector is connected to the positive electrode active material layer, or an insulating layer can be provided on a single side of the positive electrode collector, without limitation.

[0050] In some embodiments, in the volume-based particle size distribution of the first active material, the particle size (Dv50, average particle size) ranging from 0.2 μm to 15 μm, and the particle size (Dv90) ranging from the small particle size side to 90% of the volume accumulation in the volume-based particle size distribution of the first active material is less than or equal to 40 μm. When the first active material has a smaller Dv90, it can achieve a higher coverage and bonding effect on the current collector 101. In some embodiments, the average particle size (Dv50) of the second active material: the average particle size (Dv50) of the first active material is 1:1 to 40:1. The smaller the particles of the first active material, the thinner the thickness of the first active material layer can be made. For the measurement of the particle size of the active material, it can be measured by a Malvern particle size tester: the active material is dispersed in a dispersant (ethanol or acetone, or other surfactants), and after ultrasonication for 30 minutes, the sample is added to the Malvern particle size tester and the test is started.

[0051] In some embodiments, the thickness of the first active material layer 102 is 0.1 μm to 20 μm. In other embodiments, the thickness of the first active material layer 102 is 0.5 μm to 15 μm. In other embodiments, the thickness of the first active material layer 102 is 2 μm to 8 μm. In particular, the thickness of the first active material layer is not less than the particle size Dv90 of the first active material, in order to ensure the coverage of the first active material layer.

[0052] In some embodiments, the thickness of the insulating layer 104 is less than or equal to the sum of the thickness of the first active material layer 102 and the thickness of the second active material layer 103. In some embodiments, the thickness of the insulating layer 104 is greater than 0.1 μm to achieve a certain insulation effect. In other embodiments, the thickness of the insulating layer 104 is 1 μm to 30 μm. In other embodiments, the thickness of the insulating layer 104 is 5 μm to 15 μm.

[0053] In some embodiments, the density of the insulating layer 104 in the overlapping portion 105 is 60% to 90% of the density in the non-overlapping portion. In some embodiments, the length of the first active material layer in the overlapping portion is shorter than the length of the non-overlapping portion, and the density of the first active material layer in the overlapping portion is similar to that in the non-overlapping portion.

[0054] According to some embodiments of the present application, the insulating layer includes inorganic particles and / or polymers, and a suitable dispersant may also be added, the dispersant including, but not limited to, ethanol or acetone, or other surfactants. The inorganic particles are selected from the group consisting of aluminum oxide, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium sulfate and combinations thereof; the polymer is selected from the group consisting of homopolymers of vinylidene fluoride, copolymers of vinylidene fluoride, copolymers of hexafluoropropylene, polystyrene, polyphenylene vinylene, sodium polyvinyl acid, potassium polyvinyl acid, polymethyl methacrylate, polyethylene, polypropylene, polytetrafluoroethylene and combinations thereof.

[0055] In some embodiments, the electrode plate is a positive electrode plate, wherein the first active material and the second active material are each independently selected from the group consisting of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, sodium iron phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadium oxyphosphate, sodium vanadium oxyphosphate, lithium vanadate, lithium manganate, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide, lithium titanate and combinations thereof.

[0056] In some embodiments, the electrode plate is a negative electrode plate, wherein the first active material and the second active material are each independently selected from a group consisting of artificial graphite, natural graphite, mesophase carbon microbeads, soft carbon, hard carbon, silicon, silicon oxides, silicon-carbon composites, tin, tin alloys, niobium titanate, lithium titanate and combinations thereof.

[0057] In some embodiments, the first active material layer 102 and the second active material layer 103 further include a binder, which includes but is not limited to polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene and styrene-butadiene rubber, and a combination thereof. On the one hand, the binder allows the active material layer to have a better bond with the current collector, and on the other hand, the binder content increases, and the compaction density of the first active material layer 102 is lower. The content of the binder in the first active material layer 102 is 1.5% to 6% based on the total weight of the first active material layer 102, and the content of the binder in the second active material layer 103 is 0.5% to 4% based on the total weight of the second active material layer 103.

[0058] In some embodiments, the first active material layer 12 and the second active material layer 13 may further contain a certain amount of conductive agent. The conductive agent includes, but is not limited to, one of carbon nanotubes, conductive carbon black, acetylene black, graphene, Ketjen black and carbon fiber and a combination thereof. The content of the conductive agent in the first active material layer is 0.5% to 5% based on the total weight of the first active material layer, and the content of the conductive agent in the second active material layer is 0.5% to 5% based on the total weight of the second active material layer.

[0059] In addition, the first active material layer 102 or the second active material layer 103 may be subjected to some other treatments, or the current collector 101 may be subjected to some treatments, such as roughness treatment, heat treatment, etc., the working principle or effect of which may be to enhance the adhesion to the current collector. Although this application does not involve a detailed description, it is included in the scope of this application.

[0060] In some embodiments, the electrode plate serves as a positive electrode plate, and its positive electrode collector can be aluminum foil or nickel foil. The electrode plate serves as a negative electrode plate, and its negative electrode collector can be copper foil or nickel foil. However, other positive electrode collectors and negative electrode collectors commonly used in the art can be used.

[0061] It should be understood that without violating the spirit of the present application, the method for preparing the electrode plate of the present application can adopt any suitable preparation method in the art without being limited thereto.

[0062] Some embodiments of the present application further provide an electrochemical device, including a positive electrode sheet, a separator and a negative electrode sheet, wherein at least one of the positive electrode sheet and the negative electrode sheet is the electrode sheet in the above embodiments.

[0063] In some embodiments, the separator includes, but is not limited to, at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polyimide and aramid. For example, polyethylene includes at least one component selected from high-density polyethylene, low-density polyethylene and ultra-high molecular weight polyethylene. In particular, polyethylene and polypropylene have a good effect on preventing short circuits and can improve the stability of the battery through the shutdown effect.

[0064] The surface of the isolation membrane may also include a porous layer, which is disposed on at least one surface of the isolation membrane, and the porous layer includes inorganic particles and a binder, wherein the inorganic particles are selected from a combination of one or more of aluminum oxide (Al2O3), silicon oxide (SiO2), magnesium oxide (MgO), titanium oxide (TiO2), hafnium dioxide (HfO2), tin oxide (SnO2), cerium dioxide (CeO2), nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder is selected from a combination of one or more of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.

[0065] The porous layer can improve the heat resistance, oxidation resistance and electrolyte wetting performance of the isolation membrane, and enhance the adhesion between the isolation membrane and the positive electrode sheet or the negative electrode sheet.

[0066] The electrochemical device of the present application further comprises an electrolyte, which may be one or more of a gel electrolyte, a solid electrolyte and an electrolyte solution, wherein the electrolyte solution comprises a lithium salt and a non-aqueous solvent.

[0067] In some embodiments of the present application, the lithium salt is selected from one or more of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, LiBOB and lithium difluoroborate. For example, the lithium salt is selected from LiPF6 because it can provide high ionic conductivity and improve cycle characteristics.

[0068] The non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents or a combination thereof.

[0069] The carbonate compound may be a linear carbonate compound, a cyclic carbonate compound, a fluorinated carbonate compound or a combination thereof.

[0070] Examples of the above-mentioned linear carbonate compounds are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC) and combinations thereof. Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), propyl propionate (PP) and combinations thereof. Examples of fluorocarbonate compounds are 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, trifluoromethylethylene carbonate and combinations thereof.

[0071] Examples of the above carboxylic acid ester compounds are methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanoic acid lactone, valerolactone, mevalonolactone, caprolactone, methyl formate and combinations thereof.

[0072] Examples of the above ether compound are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.

[0073] Examples of the above other organic solvents are dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphoric acid esters and combinations thereof.

[0074] It should be understood that, without violating the spirit of the present application, the preparation method of the electrochemical device of the present application may adopt any suitable preparation method in the art, without being limited thereto. In some embodiments, the preparation method of the electrochemical device adopted is as follows: the above-mentioned positive electrode sheet, separator, and negative electrode sheet are wound or stacked in sequence to form an electrode assembly, and then loaded into, for example, an aluminum-plastic film, injected with an electrolyte, formed, and packaged to form a lithium-ion battery.

[0075] Although some of the exemplary embodiments above are illustrated with lithium-ion batteries, those skilled in the art should understand after reading this application that, without violating the spirit of this application, the specific examples of the electrochemical device of this application can include all kinds of primary batteries or secondary batteries. In particular, the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery.

[0076] Some embodiments of the present application further provide an electronic device, which includes the electrochemical device in the embodiments of the present application.

[0077] The electronic device of the embodiment 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, electronic cigarettes, electronic steam devices, wireless headphones, sweeping robots, drones, laptops, pen-input computers, mobile computers, electronic book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc. Specific embodiments

[0079] Some specific examples and comparative examples are listed below and battery capacity tests, battery nail penetration tests and heavy object impact tests are performed on them respectively to better illustrate the present application. Those skilled in the art will understand that the preparation method described in the present application is only an exemplary embodiment, and any other suitable preparation method is within the scope of the present application.

[0080] 1. Test Method

[0081] 1.1 Battery capacity test:

[0082] The formed lithium-ion battery (electrochemical device) was placed in an environment of 25±3℃ for 30 minutes, and then charged at a constant current of 0.5C until the voltage reached 4.4V (rated voltage). Then, the constant voltage was charged until the current reached 0.05C, and the charging was stopped. The lithium-ion battery to be tested was placed for 30 minutes. After that, the lithium-ion battery was discharged at a current of 0.2C to 3.0V, and the lithium-ion battery to be tested was placed for 30 minutes. Finally, the discharge capacity was taken as the actual battery capacity of the lithium-ion battery.

[0083] The volume energy density of lithium-ion battery = actual battery capacity / (length × width × thickness of lithium-ion battery).

[0084] 1.2 Battery nail penetration test:

[0085] Take 10 formed lithium-ion batteries and charge them at room temperature (25±3℃) at a constant current of 0.5C to a voltage of 4.4V, and further charge them at a constant voltage of 4.4V to a current of 0.05C, so that they are in a fully charged state of 4.4V. Then, perform a nail penetration test on the lithium-ion battery at room temperature, using a nail with a diameter of 2.5mm (steel nail, made of carbon steel, with a taper of 16.5mm, and a total length of 100mm) at a nail penetration speed of 30mm / s. The nail penetration depth is based on the taper of the steel nail passing through the lithium-ion battery, and observe whether the lithium-ion battery produces smoke, catches fire or explodes. If not, the lithium-ion battery is considered to have passed the nail penetration test.

[0086] 1.3 Heavy object impact test

[0087] Take 10 formed lithium-ion batteries and charge them at room temperature (25±3℃) at a constant current of 0.5C to a voltage of 4.4V, and further charge them at a constant voltage of 4.4V to a current of 0.05C, so that they are in a fully charged state of 4.4V. Then, carry out a heavy object impact test on the lithium-ion battery at room temperature. Use an impact piece (rod, with a total weight of 9.1kg) with a diameter of 15.8mm, and drop the impact piece at a vertical height of 61cm from the lithium-ion battery to impact the lithium-ion battery, and observe whether the lithium-ion battery produces smoke, catches fire or explodes. If not, the lithium-ion battery is considered to have passed the heavy object impact test.

[0088] Example 1

[0089] Aluminum foil is used as a positive electrode current collector, and a first positive electrode active material layer slurry is uniformly coated on one surface of the aluminum foil, including a first positive electrode active material (wherein the particle size of lithium iron phosphate is Dv50: 3μm, Dv90: 10μm). The first positive electrode active material layer slurry is composed of 95.8wt% lithium iron phosphate, 2.8wt% polyvinylidene fluoride and 1.4wt% conductive carbon black, and is dried at 85°C to form a first positive electrode active material layer; then, a layer of insulating layer slurry is coated on the empty current collector portion connected to the first positive electrode active material layer at one end along the length direction of the positive electrode plate and the portion on the first positive electrode active material layer, and the insulating layer slurry is composed of 98wt% aluminum oxide and 2wt% polyvinylidene fluoride, and is dried at 85°C to form an insulating layer with a thickness of 10μm, wherein the overlapping portion formed by the insulating layer covering the first positive electrode active material layer is 2mm in the length direction of the positive electrode plate; then, after drying, A second positive electrode active material layer slurry is continuously coated on the first positive electrode active material layer, wherein the second positive electrode active material layer slurry is composed of 97.8wt% lithium cobalt oxide (wherein the particle size of lithium cobalt oxide is Dv50: 13μm, Dv90: 38μm), 0.8wt% polyvinylidene fluoride and 1.4wt% conductive carbon black, and is dried at 85°C to form a second positive electrode active material layer, wherein in the length direction of the positive electrode sheet, the fifth end edge of the second positive electrode active material layer is located on the non-overlapping portion of the insulating layer (that is, extending beyond the first end edge of the first positive electrode active material layer), and the length of the second positive electrode active material layer extending beyond the overlapping portion is 1mm; on the other surface of the positive electrode collector according to Figure 8 The third positive electrode active material layer and the fourth positive electrode active material layer are prepared, the composition of the third positive electrode active material layer is the same as that of the first active material layer, the composition of the second positive electrode active material layer is the same as that of the fourth positive electrode active material, and then the positive electrode sheet is cold pressed, wherein the cold pressing pressure is 60T, the cold pressing speed is 40m / min, and after cutting and slitting, it is dried under vacuum conditions of 85°C for 4 hours to prepare the positive electrode sheet. The thickness of the first positive electrode active material layer and the third active material layer is 8μm, the thickness of the insulating layer is 10μm, and the thickness of the second positive electrode active material layer and the fourth active material layer is 50μm. Figure 8 Schematic diagram of the structure of the positive electrode sheet of Example 1. For the arrangement relationship of the positive electrode current collector 201, the first positive electrode active material layer 202, the second positive electrode active material layer 203 and the insulating layer 204 in the positive electrode sheet of Example 1, please refer to Figure 8 .

[0090] Copper foil is used as the negative electrode current collector, and a layer of graphite slurry is evenly coated on the surface of the copper foil. The slurry composition is a combination of 97.7wt% artificial graphite, 1.3wt% sodium carboxymethyl cellulose and 1.0wt% styrene-butadiene rubber. It is dried at 85°C and then cold pressed, cut and slit to prepare a negative electrode sheet.

[0091] A solution prepared by mixing lithium salt LiPF6 and a non-aqueous organic solvent (ethylene carbonate: diethyl carbonate: propylene carbonate: propyl propionate: vinylene carbonate = 20:30:20:28:2, mass ratio) in a mass ratio of 8:92 was used as the electrolyte of a lithium-ion battery.

[0092] The positive electrode sheet and the negative electrode sheet are wound together, and the positive electrode sheet and the negative electrode sheet are separated by a polyethylene separator to prepare a wound electrode assembly, which is then placed in a shell and injected with electrolyte. After vacuum packaging, standing, forming, shaping and other processes, a finished lithium-ion battery can be obtained.

[0093] Embodiment 2-6

[0094] The preparation method is the same as that of Example 1, except that the lengths of the overlapping parts of the first positive electrode active material layer and the insulating layer in the length direction of the positive electrode sheet in Examples 2-6 are different. Please refer to Table 1 for details.

[0095] Example 7

[0096] The preparation method is the same as that in Example 1, except that in Example 7, in the length direction of the positive electrode sheet, the fifth end edge of the second positive electrode active material layer is located on the overlapping part (that is, between the first end edge of the first positive electrode active material layer and the third end edge of the insulating layer), and the length of the overlapping part covered by the second positive electrode active material layer is 1 mm. Fig. 9 Schematic diagram of the structure of the positive electrode sheet of Example 7. For the arrangement relationship of the positive electrode current collector 301, the first positive electrode active material layer 302, the second positive electrode active material layer 303 and the insulating layer 304 in the positive electrode sheet of Example 7, please refer to Fig. 9 .

[0097] Example 8

[0098] The preparation method is the same as that in Example 1, except that in Example 8, in the length direction of the positive electrode sheet, the fifth end edge of the second positive electrode active material layer is flush with the third end edge of the insulating layer (that is, the second positive electrode active material layer overlaps the overlapping part), and the distance between the second positive electrode active material layer and the overlapping part is 0 mm. Fig.10 Schematic diagram of the structure of the positive electrode sheet of Example 8. For the arrangement relationship of the positive electrode current collector 401, the first positive electrode active material layer 402, the second positive electrode active material layer 403 and the insulating layer 404 in the positive electrode sheet of Example 8, please refer to Fig.10 .

[0099] Example 9

[0100] The preparation method is the same as that in Example 1, except that in Example 9, a layer of insulating layer slurry is first evenly coated on the surface of the aluminum foil; then a layer of first positive electrode active material layer slurry is coated on the empty current collector portion connected to the insulating layer at one end along the length direction of the positive electrode plate and the portion on the insulating layer, wherein the overlapping portion formed by the first positive electrode active material layer covering the insulating layer has a length of 2 mm in the length direction of the positive electrode plate, and the thickness of the first positive electrode active material layer is 10 μm, and the thickness of the insulating layer is 8 μm. Fig.11 Schematic diagram of the structure of the positive electrode sheet of Example 9. For the arrangement relationship of the positive electrode current collector 501, the first positive electrode active material layer 502, the second positive electrode active material layer 503 and the insulating layer 504 in the positive electrode sheet of Example 9, please refer to Fig.11 .

[0101] Example 10

[0102] The preparation method is the same as that of Example 9, except that in Example 10, in the length direction of the positive electrode sheet, the length of the second positive electrode active material layer extending beyond the overlapping portion is 3 mm.

[0103] Embodiment 11

[0104] The preparation method is the same as that of Example 9, except that in Example 11, in the length direction of the positive electrode sheet, the fifth end edge of the second positive electrode active material layer is located on the overlapping part (that is, between the first end edge of the first positive electrode active material layer and the third end edge of the insulating layer), and the length of the overlapping part covered by the second positive electrode active material layer is 1 mm. Fig.12 Schematic diagram of the structure of the positive electrode sheet of Example 11. For the arrangement relationship of the positive electrode current collector 601, the first positive electrode active material layer 602, the second positive electrode active material layer 603 and the insulating layer 604 in the positive electrode sheet of Example 11, please refer to Fig.12 .

[0105] Example 12

[0106] The preparation method is the same as that of Example 9, except that in Example 12, in the length direction of the positive electrode sheet, the fifth end edge of the second positive electrode active material layer is flush with the third end edge of the insulating layer (that is, the second positive electrode active material layer overlaps the overlapping part), and the distance between the second positive electrode active material layer and the overlapping part is 0 mm. Fig.13 Schematic diagram of the structure of the positive electrode sheet of Example 12. For the arrangement relationship of the positive electrode current collector 701, the first positive electrode active material layer 702, the second positive electrode active material layer 703 and the insulating layer 704 in the positive electrode sheet of Example 12, please refer to Fig.13 .

[0107] Embodiment 13

[0108] The preparation method is the same as that of Example 1, except that in Example 13, an insulating layer structure similar to that of Example 1 is provided on both sides of the positive electrode current collector. Fig.14 Schematic diagram of the structure of the positive electrode sheet of Example 13. For the arrangement relationship of the positive electrode current collector 801, the first positive electrode active material layer 802, the second positive electrode active material layer 803 and the insulating layer 804 in the positive electrode sheet of Example 13, please refer to Fig.14 .

[0109] Comparative Example 1

[0110] The preparation method is the same as that in Example 1, except that in Example 1, an insulating layer slurry is applied at a position 3 mm apart from the first positive electrode active material layer at one end along the length direction of the positive electrode plate, wherein the third end of the formed insulating layer is 3 mm apart from the first end of the first positive electrode active material layer; subsequently, a layer of second positive electrode active material layer slurry is applied on the dried first positive electrode active material layer and the empty current collector portion between the first positive electrode active material layer and the insulating layer, and dried to form a second positive electrode active material layer, wherein, in the length direction of the positive electrode plate, the fifth end edge of the second positive electrode active material layer is located on the empty current collector portion between the first positive electrode active material layer and the insulating layer, and the distance between the fifth end edge and the insulating layer is 2 mm.

[0111] After the finished lithium-ion batteries of the above embodiments and comparative examples are completed, the capacity, thickness, width, and length of the finished products are recorded to determine the volume energy density of the lithium-ion batteries. Subsequently, the finished lithium-ion batteries of the above embodiments and comparative examples are subjected to battery capacity test, battery nail penetration test, and heavy object impact test.

[0112] The experimental parameters and measurement results of various embodiments and comparative examples are shown in Table 1 below.

[0113] Table 1

[0114]

[0115]

[0116] As shown in Table 1 above, the electrode plate of the present application can effectively improve the nail penetration pass rate of the nail penetration test and the heavy object impact pass rate of the heavy object impact test by setting an overlapping portion for the first active material layer and the insulating layer, thereby increasing the safety performance of the electrochemical device and having little effect on its energy density.

[0117] By comparing Comparative Example 1 and Example 1, it can be seen that when there is a gap between the insulating layer and the first active material layer, the heavy object impact passing rate of the lithium ion battery will be greatly reduced, and the nail penetration passing rate of the lithium ion battery will be slightly reduced. For example, the lithium ion battery of Comparative Example 1 has a positive electrode current collector located between the insulating layer and the first positive electrode active material layer and is not protected by a layer with a high resistivity. When the positive electrode current collector is impacted by a heavy object, it is easy to contact the negative electrode active material layer and cause the lithium ion battery to short-circuit.

[0118] By comparing Examples 1 to 6, it can be seen that as the overlap between the insulating layer and the first active material layer increases, the heavy object impact passing rate of the lithium ion battery will also increase. However, the expansion of the overlap will also cause a decrease in the energy density of the lithium ion battery.

[0119] By comparing Examples 1, 7 and 8, it can be seen that the arrangement relationship between the second active material layer and the first active material layer and the insulating layer has a certain influence on the heavy object impact passing rate of the lithium-ion battery. When the second active material layer extends to cover the overlapping part and / or exceeds the overlapping part, the lithium-ion battery has a higher heavy object impact passing rate. In addition, the second active material layer extends and covers the overlapping part or the insulating layer to slightly increase the energy density of the lithium-ion battery.

[0120] By comparing Example 1 with Example 9, it can be seen that covering the first positive electrode active material layer with an insulating layer in the overlapping portion can have a higher heavy object impact passing rate. At the same time, by comparing Examples 9-12, it can be seen that when the fifth end of the second positive electrode active material layer covers the end of the first end of the first positive electrode active material layer, the first end 102a can be made more difficult to fall off, thereby having a better nail penetration passing rate and heavy object impact passing rate.

[0121] By comparing the above embodiments, it can be clearly understood that the electrode plate of the present application can effectively improve the safety performance of the electrochemical device and reduce the impact on the energy density.

[0122] References throughout the specification to "some embodiments", "partial embodiments", "one embodiment", "another example", "example", "specific example" or "partial example" mean that at least one embodiment or example in the present application includes the specific features, structures, materials or characteristics described in the embodiment or example. Therefore, descriptions appearing in various places throughout the specification, such as: "in some embodiments", "in an embodiment", "in one embodiment", "in another example", "in an example", "in a specific example" or "example", do not necessarily refer to the same embodiment or example in the present application. In addition, the specific features, structures, materials or characteristics herein may be combined in one or more embodiments or examples in any suitable manner.

[0123] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the present application, and that changes, substitutions and modifications may be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. An electrode plate, characterized in that: include: a current collector including a first surface; A first active material layer including a first active material; A second active material layer including a second active material; as well as Insulation layer; The first active material layer is arranged between the current collector and the second active material layer and covers a first part of the first surface of the current collector, the insulating layer covers a second part of the first surface of the current collector that is different from the first part, and in the length direction of the electrode plate, the first active material layer includes a first end and a second end, the insulating layer includes a third end and a fourth end, and the insulating layer and the first active material layer are at least partially in contact.

2. The electrode plate according to claim 1, wherein: A distance between an edge of the first end in the length direction of the electrode sheet and an edge of the third end in the length direction of the electrode sheet in the length direction of the electrode sheet is less than or equal to 20 mm.

3. The electrode plate according to claim 2, wherein: A distance between an edge of the first end in the length direction of the electrode sheet and an edge of the third end in the length direction of the electrode sheet in the length direction of the electrode sheet is 0.5 mm to 20 mm.

4. The electrode plate according to claim 3, wherein: A distance between an edge of the first end in the length direction of the electrode sheet and an edge of the third end in the length direction of the electrode sheet in the length direction of the electrode sheet is 0.5 mm to 1 mm.

5. The electrode plate according to claim 2, wherein: A distance between an edge of the first end in the length direction of the electrode sheet and an edge of the third end in the length direction of the electrode sheet in the length direction of the electrode sheet is 1 mm to 10 mm.

6. The electrode plate according to claim 1, wherein: The first end and the third end are stacked on each other to form an overlapping area, the first active material layer includes the overlapping area and a non-overlapping area excluding the overlapping area, and the second active material layer completely covers the non-overlapping area.

7. The electrode plate according to claim 1, wherein: The first end and the third end are stacked on each other to form an overlapping area, the first active material layer includes the overlapping area and a non-overlapping area excluding the overlapping area, and along the length direction of the electrode plate, the length of the second active material layer is greater than the length of the non-overlapping area.

8. The electrode plate according to claim 7, wherein: Along the length direction of the electrode sheet, the length of the second active material layer minus the length of the non-overlapping portion is less than or equal to 4 mm.

9. The electrode plate according to claim 1, wherein: In the thickness direction of the electrode sheet, the first end is arranged between the third end and the current collector.

10. The electrode plate according to claim 1, wherein: In the thickness direction of the electrode sheet, the third end is arranged between the first end and the current collector.

11. The electrode plate according to any one of claims 1 to 4, wherein: In the length direction of the electrode plate, the second active material layer includes a fifth end.

12. The electrode plate according to claim 11, wherein: The edge of the fifth end in the length direction of the electrode plate is flush with the edge of the third end in the length direction of the electrode plate.

13. The electrode plate according to claim 11, wherein: The edge of the fifth end in the length direction of the electrode sheet is located between the edge of the first end in the length direction of the electrode sheet and the edge of the third end in the length direction of the electrode sheet.

14. The electrode plate according to claim 11, wherein: The edge of the first end in the length direction of the electrode sheet is located between the edge of the third end in the length direction of the electrode sheet and the edge of the fifth end in the length direction of the electrode sheet.

15. The electrode plate according to claim 14, wherein: A distance between an edge of the first end in the length direction of the electrode sheet and an edge of the fifth end in the length direction of the electrode sheet in the length direction of the electrode sheet is less than or equal to 3 mm.

16. The electrode plate according to claim 1, wherein: The electrode plate further includes a third active material layer and a fourth active material layer, the current collector further includes a second surface, and the third active material layer is disposed between the current collector and the fourth active material layer and covers the second surface of the current collector.

17. The electrode plate according to claim 16, wherein: In the length direction of the electrode plate, the third active material layer includes a sixth end, and the edge of the sixth end in the length direction of the electrode plate is located between the edge of the first end in the length direction of the electrode plate and the edge of the fourth end in the length direction of the electrode plate.

18. The electrode plate according to claim 17, wherein: In the length direction of the electrode sheet, the fourth active material layer includes a seventh end, and the seventh end exceeds the sixth end in the length direction of the electrode sheet.

19. The electrode plate according to claim 1, wherein: The first end and the third end are stacked with each other to form an overlapping portion, and a density of the insulating layer in the overlapping portion is 60% to 90% of a density of the insulating layer not in the overlapping portion.

20. The electrode plate according to claim 1, wherein: The first active material and the second active material are each independently selected from the group consisting of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, sodium iron phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadium oxyphosphate, sodium vanadium oxyphosphate, lithium vanadate, lithium manganate, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide, lithium titanate and combinations thereof.

21. The electrode plate according to claim 1, wherein: The first active material and the second active material are each independently selected from the group consisting of artificial graphite, natural graphite, mesophase carbon microbeads, soft carbon, hard carbon, silicon, silicon oxides, silicon carbon composites, tin, tin alloys, niobium titanate, lithium titanate, and combinations thereof.

22. The electrode plate according to claim 21, wherein: The average particle size of the second active material: the average particle size of the first active material is 1:1 to 40:

1.

23. The electrode plate according to claim 21, wherein: The thickness of the first active material layer is not less than the particle size Dv90 of the first active material.

24. The electrode plate according to claim 1, wherein: The first active material layer has a thickness of 0.1 μm to 20 μm.

25. The electrode plate according to claim 21, wherein: The thickness of the insulating layer is less than or equal to the sum of the thicknesses of the first active material layer and the second active material layer.

26. The electrode plate according to claim 25, wherein: The thickness of the insulating layer is greater than 0.1 μm.

27. The electrode plate according to claim 1, wherein: The first active material layer and the second active material layer also include a binder and a conductive agent, wherein the binder is selected from the group consisting of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, styrene-butadiene rubber and a combination thereof, and The conductive agent is selected from the group consisting of carbon nanotubes, conductive carbon black, acetylene black, graphene, Ketjen black, carbon fiber and combinations thereof.

28. The electrode plate according to claim 27, wherein: The first active material layer further includes a binder, and the content of the binder accounts for 1.5% to 6% of the total weight of the first active material layer.

29. The electrode plate according to claim 27, wherein: The second active material layer further includes a binder, and the content of the binder accounts for 0.5% to 4% of the total weight of the second active material layer.

30. The electrode plate according to claim 1, wherein: The insulating layer comprises inorganic particles and / or polymers, wherein the inorganic particles are selected from the group consisting of aluminum oxide, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium sulfate, and combinations thereof, The polymer is selected from the group consisting of homopolymers of vinylidene fluoride, copolymers of vinylidene fluoride, copolymers of hexafluoropropylene, polystyrene, polyphenylene vinylene, sodium polyvinyl acid, potassium polyvinyl acid, polymethyl methacrylate, polyethylene, polypropylene, polytetrafluoroethylene and combinations thereof.

31. The electrode plate according to claim 1, wherein: The length of the second active material layer covering the insulating layer in the length direction of the electrode plate is less than or equal to 3 mm.

32. An electrochemical device, comprising a positive electrode sheet, a separator and a negative electrode sheet, wherein: The positive electrode sheet and / or the negative electrode sheet is the electrode sheet described in any one of claims 1-31.

33. An electronic device comprising the electrochemical device according to claim 32.

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