Electrode sheet, battery, and electronic device

Abstract

To provide an electrode sheet, a battery, and an electronic device that can effectively distinguish front and back surfaces of the electrode sheet.SOLUTION: The present invention provides an electrode sheet, a battery, and an electronic device, and specifically relates to a battery manufacturing technique field. The electrode sheet includes a current collector, an electrode tab, an active material layer, and an insulating layer. The current collector has a first front surface and a second front surface that are disposed relatively. The electrode tab projects from the current collector. The active material layer is installed on the first front surface and the second front surface. The insulating layer overlaps one end of the active material layer that is close to the electrode tab at least partially or has a gap therebetween. The insulating layer includes a first insulating layer disposed on the first front surface and a second insulating layer disposed on the second front surface. The first insulating layer and the second insulating layer are different in color. The present invention can distinguish the front and back surfaces of the electrode sheet by observation of the color of the first insulating layer and the second insulating layer.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to the field of battery manufacturing technology, and in particular to an electrode sheet, a battery, and an electronic device. [Background technology]

[0002] Power batteries have advantages such as high energy density, cyclic charging, safety and environmental friendliness, and are therefore widely used in fields such as new energy vehicles, consumer electronics and energy storage systems.

[0003] With the continuous development of power batteries, market requirements for batteries are increasing, resulting in the emergence of batteries with different systems and structures. To meet the design requirements of different types of batteries, the front and back surfaces of electrode sheets may differ in terms of the active material coating weight, coating thickness, coating area, etc. However, in conventional electrode sheets, the front and back surfaces of the active material layer are both black, the front and back surfaces of the general insulating layer are both white, and the front and back surfaces of the current collector are both metallic in color, so the front and back surfaces are the same color. As a result, the front and back surfaces of the electrode sheets cannot be effectively identified and distinguished by machine, and the front and back surfaces are easily reversed, resulting in problems such as capacity loss and lithium deposition in the battery.

[0004] Therefore, there is a need to provide an electrode sheet, a battery, and an electronic device that can quickly solve the above problems. Summary of the Invention [Problem to be solved by the invention]

[0005] In consideration of the above-mentioned drawbacks of the prior art, the present invention provides an electrode sheet, a battery, and an electronic device for improving the problem of being unable to effectively distinguish between the front and back surfaces of an electrode sheet. [Means for solving the problem]

[0006] To achieve the above and other related objects, the present invention provides an electrode sheet. The electrode sheet includes a current collector, an electrode tab, an active material layer, and an insulating layer. The current collector has a first surface and a second surface disposed relative to each other. The electrode tab protrudes from the current collector. The active material layer is disposed on the first surface and the second surface of the current collector. The insulating layer at least partially overlaps or is spaced from one end of the active material layer closest to the electrode tab. The insulating layer includes a first insulating layer disposed on the first surface and a second insulating layer disposed on the second surface, and the first insulating layer and the second insulating layer are different in color.

[0007] In one embodiment of the present invention, the distance between the insulating layer and one end of the active material layer is h, and the value of h is 0 to 1 mm.

[0008] In one embodiment of the present invention, the insulating layer covers a portion of the current collector and / or the electrode tab.

[0009] In one embodiment of the present invention, the first insulating layer includes a ceramic filler, an adhesive, and a color former, and the color former is an inorganic material.

[0010] In one embodiment of the present invention, the mass content of the color former in the first insulating layer is 2% to 20%, the mass content of the adhesive is 8% to 40%, and the mass content of the ceramic filler is 55% to 88%.

[0011] In one embodiment of the present invention, the mass content of the color former in the first insulating layer is 2.5% to 10%, and the mass content of the adhesive is 10% to 35%.

[0012] In one embodiment of the present invention, the color former includes at least one of titanium chrome brown, titanium nickel yellow, bismuth vanadate, chromium oxide green, cobalt green, cobalt blue, Prussian blue, cadmium red, cadmium yellow, lithopone, carbon black, iron oxide red, and iron oxide yellow.

[0013] In one embodiment of the invention, the adhesive comprises at least one of polyvinylidene fluoride, polyimide, polyphenylene sulfide, polyarylsulfone, polyether chloride, polyacrylonitrile, polyvinyl alcohol, ethylene acrylic acid copolymer, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, and polyacrylic acid.

[0014] In one embodiment of the present invention, the ceramic filler includes at least one of aluminum oxide, boehmite, titanium dioxide, zirconium dioxide, zinc oxide, barium sulfate, boron nitride, aluminum nitride, and magnesium nitride.

[0015] In one embodiment of the present invention, the color former includes at least one of titanium chrome brown, titanium nickel yellow, bismuth vanadate, chromium oxide green, cobalt green, and cobalt blue.

[0016] In one embodiment of the invention, the adhesive comprises at least one of polyvinylidene fluoride, polyimide, polyacrylonitrile, ethylene acrylic acid copolymer, ethylene vinyl acetate copolymer, and polyacrylic acid.

[0017] In one embodiment of the present invention, the ceramic filler includes at least one of aluminum oxide, boehmite, titanium dioxide, and barium sulfate.

[0018] In one embodiment of the present invention, when the average particle size of the color former is d1 and the average particle size of the ceramic filler is d2, the d1 and d2 satisfy the following relationship: 0.25≦d1 / d2≦6.

[0019] In one embodiment of the present invention, the d1 and the d2 satisfy the following relationship: 0.8≦d1 / d2≦4.

[0020] In one embodiment of the present invention, the color of the color former in the standard electrolyte solution is 0 to 20 degrees. Here, the standard electrolyte solution contains an organic solvent and a lithium salt. The organic solvent contains ethyl propyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, and fluorinated ethylene carbonate, in a volume ratio of 40:20:25:5:10. The lithium salt is a mixture of lithium hexafluorophosphate and lithium difluorooxalate borate in a mass ratio of 97:3, and the lithium salt concentration in the electrolyte solution is 1 mol / L.

[0021] In one embodiment of the present invention, the electrode sheet is a positive electrode sheet.

[0022] Another aspect of the present invention provides a battery, comprising an electrode assembly including a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet, wherein at least one of the positive electrode sheet and the negative electrode sheet employs the electrode sheet described above.

[0023] In one embodiment of the present invention, the battery further includes a housing, an electrode terminal, and a cover plate. One side of the housing is open to accommodate the electrode assembly, and the housing includes an end wall and a side wall surrounding the end wall. The electrode terminal is attached through the end wall. The cover plate covers the opening.

[0024] In one embodiment of the invention, the battery is a cylindrical battery.

[0025] The present invention further provides an electronic device, the electronic device including the battery described above, the battery being used in the electronic device. [Effects of the Invention]

[0026] The electrode sheet of the present invention has insulating layers of different colors on both sides of the active material layer at one end near the electrode tab, so that the front and back sides of the electrode sheet can be effectively distinguished by observing the color of the insulating layers, preventing the front and back sides of the electrode sheet from being reversed. Furthermore, because the insulating layers do not participate in chemical reactions, distinguishing the front and back sides of the electrode sheet with the insulating layers eliminates the need for additional marking and reduces the impact on the battery.

[0027] An inorganic material is added as a color former to at least one of the insulating layers on the front and back sides of the electrode sheet. The color former has high compatibility and stability, allowing the insulating layers on the front and back sides to display different colors while maintaining chemical stability. It is insoluble in the electrolyte and does not affect the performance of the battery. [Brief explanation of the drawings]

[0028] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces drawings that may be used in the description of the embodiments or prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without expending creative efforts.

[0029] [Figure 1] 1 is a structural schematic diagram of an electronic device according to one embodiment of the present invention; [Figure 2] 1 is a structural schematic diagram of one embodiment of a battery of the present invention. [Figure 3] 1 is a structural schematic diagram of an electrode assembly in one embodiment of a battery of the present invention. [Figure 4] 1 is a structural schematic diagram of one embodiment of an electrode sheet of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to specific examples, and those skilled in the art will easily understand other advantages and effects of the present invention from the contents disclosed herein. The present invention can be implemented or applied in different specific embodiments, and the details of each item in this specification can be modified or changed in various ways based on different perspectives and applications without departing from the spirit of the present invention. It should be noted that, unless inconsistent, the following examples and features in the examples can be combined with each other.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which the present invention pertains. The terms used in the present specification are merely for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] In this document, technical terms such as "first," "second," etc. are used only to distinguish between different objects and should not be understood as indicating or suggesting relative importance, or as implying the quantity, particular order, or hierarchical relationship of the technical features indicated.

[0033] In this document, unless otherwise specified, references to "plurality," "various," "multiple times," etc. refer to a quantity greater than or equal to two. For example, "one or more kinds" refers to more than or equal to one or two kinds.

[0034] In this document, it should be understood that the terms "preferred", "better", and "superior" are only used to describe preferred embodiments or examples, and do not limit the scope of protection of the present invention. When multiple "preferred" terms appear in one technical solution, each "preferred" term is independent of the others, unless otherwise specified and unless there is a contradictory or mutually restrictive relationship.

[0035] In the present text, the terms "furthermore", "furthermore", "particularly" and the like are used for the purpose of description and to distinguish between contents, but should not be understood as limiting the protection scope of the present invention.

[0036] In this specification, unless otherwise stated, with respect to a numerical range, the distribution of values ​​selectable within that numerical range is considered to be continuous and includes the two numerical endpoints (i.e., the minimum and maximum) of the numerical range, and every value between those two numerical endpoints. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be combined.

[0037] Unless otherwise specified, "%" and "wt%" in the text all represent mass percentage.

[0038] Electronic devices related to embodiments of the present invention are devices powered by batteries. Examples of such electronic devices include mobile phones, portable devices, laptops, electric bicycles, electric vehicles, boats, spacecraft, electric toys, and power tools. Spacecraft include airplanes, rockets, space shuttles, and spaceships. Power toys include stationary and mobile power toys, such as game consoles, toy power cars, toy power boats, and toy power airplanes. Power tools include metal-cutting power tools, polishing power tools, assembly power tools, and railroad power tools, such as power drills, grinders, wrenches, screwdrivers, hammers, impact drills, concrete vibrators, and power planers.

[0039] Referring to FIG. 1 , the electronic device 1000 includes an operating unit 1001 and a power supply system 1002. The operating unit 1001 is electrically connected to the power supply system 1002 and receives power support. Here, the operating unit 1001 is a unit component that can receive power from the power supply system 1002 and perform a corresponding operation, such as a blade rotation unit of an electric fan or a suction unit of a vacuum cleaner. The power supply system 1002 provides power support for the operation of the operating unit 1001, and includes a housing and at least one battery 100 installed within the housing. That is, one battery 100 or multiple batteries 100 may be installed within the housing. When multiple batteries 100 are installed within the housing, the multiple batteries 100 may be connected in series, parallel, or a combination thereof. A combination of series and parallel connections refers to the existence of both series and parallel connections within the multiple batteries 100. A plurality of batteries 100 may be connected directly in series, in parallel, or a combination thereof, and then the entire battery system 100 may be housed in a housing. Alternatively, a plurality of batteries 100 may first be connected in series, in parallel, or a combination thereof to form a battery module, and then the battery modules may be connected in series, in parallel, or a combination thereof to form an entire battery system housed in a housing. The housing serves to protect the batteries therein. It should be noted that the power supply system 1002 may include components such as a thermal management system and a circuit board in addition to the batteries 100, but these will not be described in detail here.

[0040] 1 , in one embodiment, the electronic device 1000 is a vehicle, which may be a gasoline vehicle, a gasoline vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a range-extended vehicle, etc., but the present invention is not limited thereto. The operating part 1001 of the vehicle is a vehicle body, and the power supply system 1002 is installed at the bottom, front, or rear of the vehicle body to provide power support for running the vehicle or operating electrical components inside the vehicle.

[0041] To meet different power needs, the power supply system 1002 may include multiple batteries 100, which may be connected in series, parallel, or a combination thereof. In this embodiment, the multiple batteries 100 may directly form a battery pack, or may first form a battery module, which then forms a battery pack.

[0042] The battery in the embodiments of the present invention refers to the smallest unit constituting a battery module or a battery pack, and the battery may be a prismatic battery, a soft pack battery, or a cylindrical battery. The present invention takes a cylindrical battery as an example, and the battery structure will be described in detail later.

[0043] Referring to FIGS. 2 and 3, the battery 100 includes a housing 110, a cover plate 120, and an electrode assembly .

[0044] An internal space for accommodating the electrode assembly 130 is formed within the housing 110. The housing may have various shapes, such as a rectangular parallelepiped, cylindrical, or hexagonal prism. Specifically, the shape of the housing 110 may be determined based on the shape and dimensions of the electrode assembly 130. For example, if the electrode assembly 130 has a cylindrical structure, the housing 110 may have a cylindrical shape; if the electrode assembly 130 has a rectangular parallelepiped structure, the housing 110 may have a rectangular parallelepiped structure. The material of the housing 110 may be a material having a certain hardness and strength, such as steel. In other embodiments, the material of the housing 110 may further be copper, iron, aluminum, aluminum alloy, plastic, or the like, but the present invention is not limited thereto.

[0045] Referring to FIG. 2 , in one embodiment, the housing 110 includes an end wall 111 and a side wall 112 surrounding the end wall 111. The side wall 112 and the end wall 111 together form a cylinder with one closed end and the other open end. A cover plate 120 is hermetically sealed at the open end of the cylinder to isolate the battery's internal environment from the external environment. An electrode terminal 113 connected to the electrode assembly 130 is provided on the end wall 111. The shape of the cover plate 120 can be adapted to the shape of the housing 110. Optionally, the cover plate 120 can be made of a material with a certain hardness and strength (e.g., an aluminum alloy). This makes the cover plate 120 less likely to deform even when subjected to pressure or impact, thereby improving the structural strength of the battery and its safety performance. The cover plate 120 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic, but the present invention is not limited thereto. In some embodiments, an insulating member may be further installed inside the cover plate 120. The insulating member is used to isolate the cover plate from the electrical connection components inside the housing 110, thereby reducing the risk of short circuits. Illustratively, the insulating member may be made of plastic, rubber, or the like.

[0046] 2 and 3, the electrode assembly 130 is a component that causes an electrochemical reaction within the battery 100. One or more electrode assemblies 130 can be included within the housing 110. The electrode assembly 130 is formed by winding or stacking electrode sheets (positive and negative electrode sheets). A separator is typically placed between the positive and negative electrode sheets to separate the positive and negative electrode sheets and prevent short circuits from occurring within the battery, while allowing active ions to pass through the separator and move between the positive and negative electrodes.

[0047] 3 and 4, the electrode sheet 10 typically includes a current collector 11 and an active material layer disposed on the current collector 11. The portions of the positive and negative electrode sheets with the active material layers constitute a main body 131 of the electrode assembly 130, while the portions of the positive and negative electrode sheets without the active material constitute electrode tabs, referred to as a first electrode tab 132 and a second electrode tab 133, respectively. The first electrode tab 132 and the second electrode tab 133 may both be located at one end of the main body 131, or may be located at both ends of the main body 131. In this embodiment, the first electrode tab 132 and the second electrode tab 133 are located at both ends of the main body 131, with the first electrode tab 132 electrically connected to the electrode terminal 113 and the second electrode tab 133 electrically connected directly or indirectly to the housing 110.

[0048] The current collector 11 may be a metal foil or a composite current collector. Specifically, the selection of the current collector 11 is related to the type of electrode sheet. For example, when the electrode sheet 10 is a positive electrode sheet, the current collector 11 may be an aluminum foil, with a thickness of 5 to 20 μm, more specifically, 10 to 15 μm, or even more specifically, 12 μm. The current collector 11 may also be a composite current collector, with a polymer resin material as an intermediate layer and aluminum layers deposited on both the upper and lower surfaces. The polymer resin material may be polyethylene terephthalate (PET), polypropylene (PP), polyimide (PI), polystyrene (PS), polyamide (PA), or the like. When the electrode sheet 10 is a negative electrode sheet, the current collector 11 may be copper foil, with a thickness of 4 to 15 μm, preferably 5 to 10 μm, and even more preferably 8 μm. The current collector 11 may be a composite current collector, with a polymer resin material as an intermediate layer, and copper deposited on both the upper and lower surfaces. The polymer resin material may be polyethylene terephthalate (PET), polypropylene (PP), polyimide (PI), polystyrene (PS), polyamide (PA), or the like.

[0049] The current collector 11 has a first surface and a second surface disposed relative to each other along its thickness direction, and an active material layer can be disposed on at least one of the first and second surfaces. Furthermore, an active material layer can be disposed on both the first and second surfaces. For ease of explanation, the active material layer disposed on the first surface will be referred to as the first active material layer 12, and the active material layer disposed on the second surface will be referred to as the second active material layer 13. The active material layer includes an active material, a conductive agent, and a binder. The active material is the main substance participating in the electrochemical reaction, and its selection depends on the type of electrode sheet and battery. For example, in a lithium-ion battery, when the electrode sheet 10 is a positive electrode sheet, the active material can be selected from lithium phosphate, lithium transition metal oxide, and their modifications. Examples of lithium phosphate include, but are not limited to, lithium iron phosphate, lithium manganese iron phosphate, and lithium manganese phosphate. Lithium transition metal oxides include, but are not limited to, lithium nickel-cobalt manganese oxide, lithium nickel-cobalt oxide, lithium manganese-cobalt oxide, lithium nickel-cobalt manganese aluminum oxide, and lithium manganese oxide. The present invention is not limited to these materials, and other conventional materials usable as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. When the electrode sheet 10 is a negative electrode sheet, the active material can be selected from carbon materials and / or silicon materials. The carbon material can be selected from, for example, artificial graphite, natural graphite, soft carbon, hard carbon, mesophase carbon microspheres, etc., and the silicon material can be selected from, for example, one or more of silicon, silicon oxide compounds, and silicon carbide compounds. However, the present invention is not limited to these materials, and other conventional materials usable as battery negative electrode active materials can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0050] Conductive agents can improve electronic conductivity and collect microcurrents between active materials and between active materials and current collectors, thereby reducing contact resistance and accelerating electron transfer rates to ensure good charge-discharge performance of the battery. Conductive agents can also improve the processability of electrodes, facilitating electrolyte penetration into the electrodes and effectively increasing the lithium ion transfer rate within the battery materials, thereby improving the charge-discharge efficiency and service life of the battery. In some embodiments, the conductive agent includes at least one of conductive carbon black (SP), conductive graphite, carbon fiber, carbon nanotubes, and graphene. However, the present invention is not limited thereto. Optionally, the conductive agent can be conductive carbon black, a combination of carbon fiber and conductive carbon black, or a combination of carbon nanotubes and graphene.

[0051] The binder is used to bond the active material and the conductive agent, providing a certain adhesive force to the active material layer and adhering it to the current collector 11. For example, the negative electrode binder is selected from at least one of polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), and carboxymethyl cellulose (CMC). For example, the binder is polyvinylidene fluoride or a combination of styrene butadiene rubber and carboxymethyl cellulose. The positive electrode binder is selected from one or a mixture of polyvinylidene fluoride (PVDF), polyvinylidene hexafluoropropylene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, and styrene butadiene rubber.

[0052] With the continuous development of new energy technologies, the applications of batteries are becoming increasingly widespread, and the number of battery types is increasing. To accommodate the development of different battery types, differences in electrode sheet design may arise. For example, in cylindrical batteries, the diameter of the cylindrical electrode assembly and the inner diameter of the housing are relatively close, with a relatively small gap between them, in order to pursue energy density. Furthermore, cylindrical batteries are characterized by the fact that the curvatures of the inner and outer diameters do not match. Therefore, the energy density can be significantly improved by designing electrode sheets with different surface densities on the front and back sides. Therefore, it is particularly important to distinguish the front and back sides of the positive electrode sheet of cylindrical batteries.

[0053] However, because the first active material layer 11 and the second active material layer 12 have the same material composition and are displayed in the same color, it is difficult to effectively distinguish between the front and back surfaces of the electrode sheet 10. To solve this problem, the positions of the inactive material layers are usually marked manually using a marker pen. While this method can distinguish between the front and back surfaces of the electrode sheet, it does not provide error prevention and is inefficient, making it unsuitable for mass production.

[0054] Based on this, the present invention provides an electrode sheet. By providing insulating layers of different colors on the first and second surfaces of the current collector, the front and back surfaces of the electrode sheet can be effectively distinguished by observing the colors of the insulating layers. Furthermore, because the insulating layer is provided at one end of the active material layer close to the electrode tab, it does not participate in the chemical reaction and has relatively little impact on the battery.

[0055] Referring to FIG. 4, the electrode sheet 10 includes a current collector 11, an electrode tab, an active material layer, and an insulating layer. The active material layer is disposed on the first and second surfaces of the current collector 11, and the electrode tab protrudes from the current collector 11. The electrode tab may be formed by punching out an uncoated area of ​​the current collector 11, or may be formed separately from the current collector 11 and then welded to the current collector 11. The insulating layer is disposed at an end of the active material layer close to the electrode tab and may at least partially overlap the end of the active material layer close to the electrode tab, or may be spaced apart from the active material layer. It should be noted that when the insulating layer and the active material layer are spaced apart, the distance between the insulating layer and one end of the active material layer is h, and the value of h is 0 to 1 mm. In actual production, the value of h is 0.5 mm, and when h = 0, it indicates that the insulating layer and the active material layer are adjacent to each other or overlap each other. That is, one end of the insulating layer close to the active material layer covers the surface of the active material layer, and the other end of the insulating layer contacts the current collector.

[0056] The insulating layer of the present invention includes a first insulating layer 14 disposed on the first surface and a second insulating layer 15 disposed on the second surface. Furthermore, the first insulating layer 14 and the second insulating layer 15 are displayed in different colors, so that the front and back surfaces of the electrode sheet 10 can be distinguished by observing the colors of the first insulating layer 14 and the second insulating layer 15. Furthermore, because the insulating layer does not participate in chemical reactions, using the insulating layer to distinguish between the front and back surfaces of the electrode sheet is a more preferable option, and there is no need to add any additional markings, so the impact on the battery is relatively small.

[0057] In one embodiment, the first insulating layer 14 includes a ceramic filler, an adhesive, and a color former, the color former being an inorganic material. Organic color formers are generally polar substances and therefore have similar compatibility with polar organic solvents in battery electrolytes, which can cause side reactions with the electrolyte and reduce battery capacity. In contrast, inorganic materials have stable chemical properties. In the present invention, the inorganic color former is selected to display color while avoiding chemical reactions with the electrolyte, thereby avoiding adverse effects on battery performance.

[0058] In some embodiments, the color former includes at least one of titanium chrome brown, titanium nickel yellow, bismuth vanadate, chromium oxide green, cobalt green, cobalt blue, Prussian blue, cadmium red, cadmium yellow, lithopone, carbon black, iron oxide red, and iron oxide yellow, but the present invention is not limited thereto. That is, the color former may be any one of the above materials or a combination of any two or more of the above materials. Furthermore, the color former may include one or more of titanium chrome brown, titanium nickel yellow, bismuth vanadate, chromium oxide green, cobalt green, and cobalt blue. For example, the color former may be titanium chrome brown, or the color former may be bismuth vanadate, or the color former may be a combination of cobalt green and cobalt blue, etc. The chromaticity of the color former selected in the present invention in the standard electrolyte solution is 0 to 20 degrees, more specifically, the chromaticity of the color former in the standard electrolyte solution is 2.5 to 15, and even more specifically, the chromaticity of the color former in the standard electrolyte solution may be 5, 10, or 15, etc.

[0059] It should be noted that the method for measuring the chromaticity of the color former is as follows.

[0060] 1. Prepare the experimental sample: Cut out the insulating layer area of ​​the electrode sheet and place it in a transparent glass bottle. Add the standard electrolyte solution so that the electrode sheet is completely immersed in the standard electrolyte solution (the mass ratio of electrolyte to electrode sheet is 95:5). Seal and store at 25°C and humidity ≤ 50% for 3 days, then remove the electrode sheet.

[0061] 2. Prepare a blank sample: Place the standard electrolyte in a separate transparent glass bottle, seal it, and store it at 25°C and humidity ≦50% for 3 days.

[0062] 3. Measure the color of the blank sample and the experimental sample using the standard platinum-cobalt colorimetric method: Compare the color of the blank sample and the experimental sample with the color of the standard solution, and record the color of the sample that is closest to the color of the standard solution as the color value of the measured sample. Final color of the color developer = color of the experimental sample - color of the blank sample.

[0063] The formulation of the standard electrolyte is as follows: propylene ethylene carbonate (PEC): ethyl methyl carbonate (EMC): ethylene carbonate (EC): propylene carbonate (PC): fluoroethylene carbonate (FEC) in a volume ratio of 40:20:25:5:10 is mixed to prepare a homogeneous organic solvent. Under a dry argon atmosphere, lithium hexafluorophosphate (LiPF6) and lithium difluorooxalatoborate (LiODFB) are added to the organic solvent in a mass ratio of 97:3 as a mixed lithium salt, and the mixture is stirred until completely dissolved to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0064] The standard solutions used in the above tests can be purchased directly or prepared by hand. Color standard solution: 500 Hazen; colorimetric tube: 100 ml; Preparation of each colorimetric standard solution: Preparation of the 2.5 Hazen standard solution: Use a pipette to measure exactly 0.5 ml of the 500 Hazen color standard solution into a 100 ml volumetric flask, dilute with pure water to the volume mark, shake well, and then transfer to the 100 ml colorimetric tube up to the scale line; Preparation of the 5 Hazen standard solution: Use a pipette to measure exactly 1 ml of the 500 Hazen color standard solution into a 100 ml volumetric flask, dilute with pure water to the volume mark, shake well, and then transfer to the 100 ml colorimetric tube up to the scale line; and so on.

[0065] In some embodiments, the ceramic filler includes at least one of aluminum oxide, boehmite, titanium dioxide, zirconium dioxide, zinc oxide, barium sulfate, boron nitride, aluminum nitride, and magnesium nitride. However, the present invention is not limited to these materials, and other ceramic fillers used in the insulating layer of the electrode sheet can also be used. The ceramic filler in the present invention may be any one of the above-mentioned materials, or any combination of the above-mentioned materials. Furthermore, the ceramic filler may be selected from at least one of aluminum oxide, boehmite, titanium dioxide, and barium sulfate. For example, the ceramic filler may be aluminum oxide, boehmite, or a combination of titanium dioxide and barium sulfate. It should be noted that the ceramic filler includes, but is not limited to, the above-mentioned materials. When the ceramic filler is a combination of multiple types, there is no limit to the ratio between the components, and they can be mixed in any ratio.

[0066] In some embodiments, the adhesive includes at least one of polyvinylidene fluoride (PVDF), polyimide, polyphenylene sulfide, polyarylsulfone, polyether chloride, polyacrylonitrile, polyvinyl alcohol, ethylene acrylic acid copolymer (EAA), ethylene vinyl acetate copolymer (EVA), ethylene ethyl acrylate copolymer (EEA), and polyacrylic acid (PAA). That is, the adhesive can be selected from any one of the above types or a combination of any two or more types. For example, the adhesive is PVDF, or the adhesive is polyimide, or the adhesive is a composition of EAA and EEA mixed in any ratio. Furthermore, the adhesive includes at least one of PVDF, polyimide, polyacrylonitrile, EAA, EVA, and PAA, or even more particularly, the adhesive is PVDF. The adhesive can also be selected from types of adhesives not listed above.

[0067] The first insulating layer 14 is obtained by uniformly dispersing a ceramic filler, an adhesive, and a color former in an organic solvent (e.g., N-methylpyrrolidone (NMP)), coating the resulting mixture on the current collector 11, and drying the resulting mixture. Therefore, the blending ratio of the ceramic filler, adhesive, and color former in the first insulating layer 14 significantly affects the color development, adhesive strength, and other properties of the first insulating layer 14. In some embodiments, the mass content of the color former in the first insulating layer 14 is 2% to 20%, e.g., 2%, 5%, 10%, 15%, or 20%, based on the total mass of the dry materials in the first insulating layer 14. Furthermore, the mass content of the color former is 2.5% to 10%, and optionally, the mass content of the color former is 2.5%, 4%, 6%, or 8%. If the content of the color former in the first insulating layer 14 is too low, the displayed color will be pale, making it difficult to distinguish colors. If the color former content is too high, the static viscosity of the slurry increases, making coating difficult. The mass content of the adhesive in the first insulating layer 14 is 8% to 40%. Furthermore, the mass content of the adhesive in the first insulating layer 14 is 10% to 35%, and optionally, the mass content of the adhesive may be 15%, 20%, 30%, or 35%, for example. If the adhesive content in the first insulating layer 14 is too low, the adhesive strength may be insufficient, which may result in partial detachment. If the adhesive content is too high, the first insulating layer 14 may stick when punching out the current collector. The mass content of the ceramic filler in the first insulating layer 14 is 55% to 88%, for example, 55%, 65%, 75%, 85%, or 88%.

[0068] One of the main roles of the insulating layer is to provide insulation, preventing contact between the positive and negative electrode sheets during use and causing a short circuit. Another role is to reduce the occurrence of burrs when punching out electrode tabs. By setting the ratio of ceramic particles, color former, and adhesive in the first insulating layer of the present invention within the above ratio range, the insulating layer itself can be realized while also displaying colors other than white, making it easy to distinguish between the front and back surfaces of the electrode sheet.

[0069] The inventors have found through their research that the particle size ratio of the color former and the ceramic filler in the insulating layer also affects the color. In one embodiment, where d1 is the average particle size of the color former and d2 is the average particle size of the ceramic filler, d1 and d2 satisfy the following: 0.25≦d1 / d2≦6. Furthermore, 0.8≦d1 / d2≦4. Furthermore, d1 / d2 may be 1, 2, 3, or 4, etc. As long as the particle size ratio of the two is within the above range, the first insulating layer 14 can display a distinct color.

[0070] It should be noted that the average particle size, i.e., D50, can be defined as the particle size corresponding to 50% in the particle size distribution curve based on cumulative volume, and can be measured by laser diffraction. D50 has a meaning well known in the art and can be measured by instruments and methods already known in the art. For example, D50 refers to the GB / T 19077.1-2016 standard and is measured using a laser particle size analyzer (e.g., Malvern Master Sizer 3000). D50 is the particle size corresponding to 50% of the cumulative volume distribution of a substance.

[0071] Referring to FIG. 4 , in some embodiments, the second insulating layer 15 employs a similar formulation to the first insulating layer 14, i.e., includes a ceramic filler, an adhesive, and a color former. In this case, the color former in the second insulating layer 15 is different from the color former in the first insulating layer 14, so that the second insulating layer 15 and the first insulating layer 14 can display different colors. For example, one may display yellow and the other green. In other embodiments, the second insulating layer 15 may employ a conventional white ceramic coating, i.e., includes a ceramic filler and an adhesive but does not include a color former.

[0072] In some embodiments, the electrode tabs may be formed by punching out uncoated areas of the current collector 11, or may be formed separately from the current collector 11 and then welded together. The insulating layer is disposed between the active material layer and the electrode tabs and covers a portion of the current collector and / or the electrode tabs. That is, the insulating layer may cover only a portion of the electrode tabs, or may cover a portion of the current collector 11 and a portion of the electrode tabs. By covering the electrode tabs with the insulating layer, the base portions of the electrode tabs can be fixed, thereby preventing the electrode tabs from breaking.

[0073] The positive electrode sheet and / or negative electrode sheet of the electrode assembly 130 adopts the structure of the electrode sheet 10 provided by the present invention. That is, both the positive electrode sheet and the negative electrode sheet may adopt the above-described electrode sheet structure, or only one of them may adopt the above-described structure, and specific settings can be made according to actual needs. Furthermore, the positive electrode sheet adopts the above-described electrode sheet 10 structure, and the negative electrode sheet adopts a conventional electrode sheet structure.

[0074] In some embodiments, the battery 100 further includes an electrolyte solution used to transport metal ions between the positive and negative electrode sheets. The electrolyte solution includes an electrolyte salt and an organic solvent. By way of example, the electrolyte salt is a lithium salt, which can be selected from one or more of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP). The organic solvent can be selected from one or several of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), and ethyl butyrate (EB).

[0075] In some embodiments, additives can be further added to the electrolyte solution. For example, the electrolyte solution can include a negative electrode film-forming additive, a positive electrode film-forming additive, an additive for improving the overcharge performance of the battery, an additive for improving the high-temperature performance of the battery, an additive for improving the low-temperature performance of the battery, etc.

[0076] The manufacturing process of the above battery is, for example, as follows.

[0077] (1) Preparation of the positive electrode sheet

[0078] The positive electrode active material, conductive agent, and binder are mixed in a certain ratio, and a solvent (e.g., N-methylpyrrolidone, abbreviated as NMP) is added. The mixture is thoroughly stirred and mixed to form a uniform positive electrode slurry. The positive electrode slurry is then coated onto a positive electrode current collector, followed by drying, cold pressing, and other processes to obtain a positive electrode sheet. The required electrode sheet is then obtained by coating both sides of the active material layer with insulating layers (one side is coated with a color-forming ceramic coating according to the design, and the other side is coated with a standard white ceramic coating). The ratio of each component in the positive electrode slurry can be set based on the usual ratios and is not limited here.

[0079] (2) Preparation of negative electrode sheet

[0080] The negative electrode active material, binder, thickener, and conductive agent are mixed according to the appropriate ratio, and then deionized water is added and thoroughly stirred to form a uniform negative electrode slurry. The negative electrode slurry is then coated onto a negative electrode current collector, followed by drying, cold pressing, and other processes to obtain a negative electrode sheet. The ratio of each component in the negative electrode slurry can be set based on typical ratios and is not limited here.

[0081] (3) Separator

[0082] The separator can be any known porous structure separator with excellent chemical and mechanical stability. For example, the separator material can be selected from one or more of polyethylene (PE) film, polypropylene (PP) film, polyvinylidene fluoride film, and multilayer composite films containing one or more of these. The separator can be a single-layer separator or a multilayer composite separator, and is not particularly limited here. When the separator is a multilayer composite separator, the materials of each layer can be the same or different, and is not particularly limited here.

[0083] (4) Preparation of electrolyte

[0084] In an argon atmosphere glove box with a moisture content of <10 ppm, the organic solvents are mixed uniformly at a certain ratio to obtain an organic solvent. The electrolyte salt is added to the organic solvent and mixed and stirred to prepare an electrolyte solution of the required concentration.

[0085] (5) Battery assembly

[0086] The positive electrode sheet, separator, and negative electrode sheet are arranged in this order, with the separator positioned between the positive and negative electrode sheets to act as an insulator, and then wound or stacked to obtain an electrode assembly. The electrode assembly is placed in a housing, dried, and then an electrolyte is injected. A battery is then obtained by sealing, leaving it to stand, and carrying out processes such as chemical formation.

[0087] The electrode assembly in the battery of the present invention employs the above-described electrode sheet. The insulating layers on the front and back of the electrode sheet display different colors, allowing the front and back of the electrode sheet to be effectively distinguished by color. Furthermore, the color former in the insulating layer is an inorganic material, but the color former has relatively good chemical stability and does not react chemically with the battery electrolyte, so it does not affect battery performance.

[0088] The technical solutions of the present invention will be described in detail below through several specific examples and comparative examples. Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by conventional methods in this field, and the equipment used in the examples is all commercially available.

[0089] Example 1

[0090] This embodiment provides an electrode sheet. The electrode sheet is a positive electrode sheet, and includes a current collector, a first active material layer, a second active material layer, a first insulating layer, and a second insulating layer. Here, the current collector is an aluminum foil current collector, and the first active material layer and the second active material layer are disposed on a first surface and a second surface, respectively, that are disposed relative to each other along the thickness direction of the aluminum foil current collector. The first insulating layer is disposed on the first surface and partially overlaps the first active material layer. The second insulating layer is disposed on the second surface and partially overlaps the second active material layer. Here, the first insulating layer includes a ceramic filler, an adhesive, and a color former, and the second insulating layer is a ceramic coating without the addition of a color former.

[0091] In this embodiment, the first insulating layer contains boehmite (ceramic filler), PVDF (adhesive, molecular weight 900,000 to 1,100,000), and bismuth vanadate (color former). Here, the mass content of PVDF in the first insulating layer is 18%, the mass content of bismuth vanadate is 2.5%, and the remainder is boehmite. The average particle size of the boehmite is 1.6 μm, and the particle size ratio of bismuth vanadate to boehmite is 2.3.

[0092] The preparation method is as follows: first, boehmite and bismuth vanadate are premixed at a rotation speed of 1500 rpm / min for 30 minutes, then the adhesive PVDF is added and dispersed at a rotation speed of 2000 rpm / min for 90 minutes, and then the solvent NMP is added to prepare a ceramic slurry with a solid content of 30%.

[0093] The specific manufacturing process of the electrode sheet is as follows: 0.8 Co 0.1 Mn 0.1 O2), conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are mixed uniformly in a weight ratio of 96.5:1.5:2, and the solvent N-methylpyrrolidone (NMP) is added. The mixture is thoroughly stirred to make it uniform, thereby obtaining a positive electrode slurry.

[0094] The positive electrode slurry is coated onto a first surface and a second surface of an aluminum foil current collector, respectively, and dried to obtain a first active material layer and a second active material layer.

[0095] The ceramic slurry prepared above is coated on the first surface on the side of the first active material layer, and the ceramic slurry without added color former is coated on the second surface on the side of the second active material layer, followed by steps such as drying, cold pressing, and cutting to obtain a positive electrode sheet.

[0096] This example further provides a battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, wherein the positive electrode sheet is the positive electrode sheet prepared above.

[0097] Negative electrode sheet: The negative electrode material, artificial graphite, conductive agent, acetylene black, thickener, CMC, and binder, SBR, are mixed in a mass ratio of 96.4:1:1.2:1.4, and then deionized water is added and thoroughly stirred to obtain negative electrode slurry. The negative electrode slurry is then uniformly coated onto the copper foil negative electrode current collector, followed by drying, cold pressing, cutting, and other processes to produce the negative electrode sheet.

[0098] Separator: 11 μm thick PE porous membrane.

[0099] Electrolyte: In an argon atmosphere glove box with a water content of <10 ppm, PEC, EMC, EC, PC, and FEC were mixed uniformly in a volume ratio of 40:20:25:5:10 to obtain an organic solvent. LiPF6 and LiODFB were added to the organic solvent as a lithium salt mixture in a mass ratio of 97:3, and the mixture was stirred to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0100] The positive electrode sheet, separator, and negative electrode sheet are stacked in this order, rolled up, and molded, then packaged in an aluminum laminate film. After drying, the electrolyte is injected, and the resulting product is sealed, left to stand, and chemically formed to produce a soft-pack battery (i.e., a lithium-ion secondary battery) with a capacity of 46 Ah.

[0101] Example 2

[0102] The difference between this example and Example 1 is that the content of the color former in the first insulating layer is 5%, but the rest is the same.

[0103] Example 3

[0104] The difference between this example and Example 1 is that the content of the color former in the first insulating layer is 10%, but the rest is the same.

[0105] Example 4

[0106] The difference between this example and Example 1 is that the content of the color former in the first insulating layer is 20%, but the rest is the same.

[0107] Example 5

[0108] The difference between this example and Example 1 is that the content of adhesive in the first insulating layer is 8%, but the rest is the same.

[0109] Example 6

[0110] The difference between this example and example 5 is that the content of adhesive in the first insulating layer is 11%, but the rest is the same.

[0111] Example 7

[0112] The difference between this example and Example 1 is that the content of adhesive in the first insulating layer is 35%, but the rest is the same.

[0113] Example 8

[0114] The difference between this example and Example 1 is that the content of adhesive in the first insulating layer is 40%, but the rest is the same.

[0115] Example 9

[0116] The difference between this embodiment and embodiment 2 is that cobalt blue is used as the color former in the first insulating layer, and the rest is the same.

[0117] Example 10

[0118] The difference between this example and Example 2 is that cobalt green is used as the color former in the first insulating layer, but the rest is the same.

[0119] Example 11

[0120] The difference between this example and example 2 is that the color former in the first insulating layer is bismuth vanadate + cobalt green, and the content of bismuth vanadate and cobalt green is 3% + 3%, but the rest is the same.

[0121] Example 12

[0122] The difference between this example and example 2 is that the molecular weight of the adhesive PVDF in the first insulating layer is 1.3 million to 1.7 million.

[0123] Example 13

[0124] The difference between this example and example 2 is that the adhesive in the first insulating layer is polyimide, and the molecular weight of the polyimide is 700,000 to 1,200,000.

[0125] Example 14

[0126] The difference between this example and Example 2 is that the adhesive in the first insulating layer is a combination of polyimide and EAA, and its molecular weight is 50,000 to 400,000.

[0127] Example 15

[0128] The difference between this example and example 2 is that the molecular weight of the adhesive in the first insulating layer is 800,000 to 1,200,000.

[0129] Example 16

[0130] The difference between this example and Example 15 is that the ceramic filler in the first insulating layer is aluminum oxide.

[0131] Example 17

[0132] The difference between this example and Example 15 is that the particle size of the ceramic filler in the first insulating layer is 0.3 μm.

[0133] Example 18

[0134] The difference between this example and Example 15 is that the particle size of the ceramic filler in the first insulating layer is 4 μm.

[0135] Example 19

[0136] The differences between this example and example 2 are that in the first insulating layer, the particle size ratio of the colorant to the ceramic filler is 0.25, the particle size of the ceramic filler is 4 μm, the molecular weight of the adhesive is 800,000 to 1,200,000, and the mass content of bismuth vanadate is 3%.

[0137] Example 20

[0138] The difference between this example and Example 19 is that in the first insulating layer, the particle size ratio of the color former to the ceramic filler is 0.8.

[0139] Example 21

[0140] The difference between this example and Example 19 is that in the first insulating layer, the particle size ratio of the color former to the ceramic filler is 1.3.

[0141] Example 22

[0142] The difference between this example and Example 19 is that the particle size ratio of the color former to the ceramic filler is 4 in the first insulating layer.

[0143] Example 23

[0144] The difference between this example and Example 19 is that the particle size ratio of the color former to the ceramic filler is 6 in the first insulating layer.

[0145] Comparative Example 1

[0146] The difference between this comparative example and Example 1 is that no color former was added to the first insulating layer.

[0147] Comparative Example 2

[0148] The difference between this comparative example and Example 1 is that the mass content of the color former in the first insulating layer is 1%.

[0149] Formulation of color-developing ceramic coating layers in Examples 1 to 23 and Comparative Examples 1 and 2 [Table 1] JPEG2025144539000003.jpg50161

[0150] 5 g of the insulating layer region of the positive electrode sheets prepared in Examples 1 to 23 and Comparative Examples 1 and 2 was cut out and placed in 95 g of standard electrolyte, sealed and stored at 25°C and humidity ≦50% for 3 days, and the state of the insulating layer region of the electrode sheet was observed. The chromaticity was then measured. The specific measurement process can be seen in the above text, and the measurement results can be seen in Table 2.

[0151] Measurement results of positive electrode sheets of Examples 1 to 23 and Comparative Examples 1 and 2 [Table 2]

[0152] Tables 1 and 2 reveal the following: (1) Comparing Examples 1 to 4 and Comparative Examples 1 and 2, assuming other conditions are the same, as the color former content in the first insulating layer increases, the color displayed by the first insulating layer gradually darkens, making it easier to distinguish between the first and second insulating layers of the positive electrode sheet. Comparative Example 1 does not contain any color former and displays a white color. Therefore, the colors of the insulating layers on both the front and back sides of the positive electrode sheet are the same and indistinguishable. Comparative Example 2 adds a color former, but the color former content is low, so the color change is not clear and the white color is still displayed, making it impossible to distinguish between the two sides of the electrode sheet. Example 4 contains too much color former, so the color is relatively dark and the front and back sides of the electrode sheet can be distinguished. However, the relatively high color former content makes the slurry relatively viscous at rest, making coating difficult. Therefore, by maintaining the color former content in the insulating layer within an appropriate ratio range, it is possible to display colors other than white and also facilitate coating. At the same time, since the insulating layer (without color former) has one white side and the other colored side, the white side is convenient for distinguishing the insulating layer from the active material layer using a CCD, and by making the active material layer black, this black-and-white contrast makes it easier to distinguish. Therefore, it is preferable that the insulating layer has one colored side and the other white side.

[0153] Furthermore, the chromaticity values ​​of Examples 1 to 4 and Comparative Examples 1 and 2 reveal the following: as the color former content increases, the solubility of the color former in the electrolyte solution increases, and the chromaticity value also increases accordingly. It should be noted that the scale interval for chromaticity comparison is 2.5. That is, the scale values ​​are 0, 2.5, 5, 7.5, 10, 12.5, 15, etc. in order. In the measurement process, the chromaticity values ​​are all multiples of 2.5. That is, the chromaticity is determined based on which scale it is closest to.

[0154] (2) Comparing Example 1 with Examples 5-8, we found that the adhesive content in the insulating layer does not affect the color of the coating, but does affect the adhesive strength between the coating and the current collector. Assuming other conditions are the same, as the adhesive content in the insulating layer increases, the adhesive strength between the coating and the current collector also gradually increases. When the adhesive content in the insulating layer is less than 10%, the coating partially peels off after immersion in electrolyte for 15 days. When the adhesive content in the insulating layer is more than 35%, the adhesive strength between the coating and the current collector is relatively strong, resulting in sticking when the electrode sheet is brought into close contact with the laser. Therefore, the adhesive content in the insulating layer is preferably 10-35%.

[0155] (3) Comparing Examples 9 to 11, the following can be seen: By using different types of color formers in the insulating layer, all of them can display colors other than white. Therefore, by using these in the insulating layer of the electrode sheet, all of them can effectively distinguish between the front and back surfaces.

[0156] (4) Comparing Examples 12 to 14, the following can be seen: The type and molecular weight of the adhesive do not affect the color displayed by the insulating layer.

[0157] (5) Comparing Examples 15 to 18, the following can be seen: By employing different types of ceramic fillers and ceramic fillers with different particle sizes in the insulating layer, it is possible to display colors other than white. Therefore, by using these in the insulating layer of the electrode sheet, all of them can effectively distinguish between the front and back surfaces of the electrode sheet.

[0158] (6) Comparing Examples 19 to 23, we find that the particle size ratio of the color former to the ceramic filler affects the color displayed by the insulating layer. Assuming other conditions are the same, the larger the particle size ratio of the color former to the ceramic filler, the darker the color displayed by the insulating layer, which is advantageous for distinguishing the front and back surfaces of the electrode sheet.

[0159] The electrode sheet of the present invention has insulating layers of different colors on both sides of the active material layer at one end closest to the electrode tab, allowing the front and back sides of the electrode sheet to be effectively distinguished by observing the color of the insulating layers. Furthermore, by adding an inorganic material as a color former to at least one of the insulating layers on the front and back sides of the electrode sheet, compatibility and stability are enhanced. In other words, the insulating layers on both sides can display different colors while maintaining chemical stability and being insoluble in the electrolyte, so battery performance is not affected. Therefore, the present invention effectively overcomes the practical problems of the prior art and has great utility and significance. By positioning the first insulating layer 14 on the side of the electrode sheet 10 facing the central hole of the electrode assembly 130 (i.e., at the exact center position of the electrode assembly 130, or in the case of a cylindrical battery, at the center of the electrode assembly 130), the outer side of the electrode sheet 10 of the electrode assembly 130 can be made into a white insulating layer, which makes it easy to identify the distance of the electrode sheet 10, i.e., the distance at which the first insulating layer 14 exceeds the active material layer of the negative electrode sheet, using a CCD. This avoids the risk of contact short circuit caused by the distance of the first insulating layer 14 being too close to the distance of the negative electrode active material layer, and improves the safety of the battery. [Industrial Applicability]

[0160] The present invention provides an electrode sheet, a battery, and an electronic device for resolving the problem of being unable to effectively distinguish between the front and back surfaces of an electrode sheet.

[0161] The above-described embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Those skilled in the art may modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should be included in the scope of the claims of the present invention. [Explanation of symbols]

[0162] 1000 Electronic Devices 1001 Operating part 1002 Power System 100 batteries 110 Case 111 End Wall 112 Side wall 113 Electrode terminal 120 cover plate 130 Electrode Assembly 131 Main body 132 First electrode tab 133 Second electrode tab 10 Electrode sheet 11 Current collector 12 First active material layer 13 Second active material layer 14 First insulating layer 15 Second insulating layer

Claims

1. a current collector having a first surface and a second surface disposed relative to one another; an electrode tab protruding from the current collector; an active material layer disposed on the first surface and the second surface; an insulating layer at least partially overlapping or spaced from one end of the active material layer near the electrode tab, the insulating layer including a first insulating layer disposed on the first surface and a second insulating layer disposed on the second surface; wherein the first insulating layer and the second insulating layer are different in color.

2. 2. The electrode sheet according to claim 1, wherein the distance between the insulating layer and one end of the active material layer is h, and the value of h is 0 to 1 mm.

3. The electrode sheet according to claim 1 , wherein the insulating layer covers a portion of the current collector and / or the electrode tab.

4. 2. The electrode sheet according to claim 1, wherein the first insulating layer contains a ceramic filler, an adhesive, and a color former, and the color former is an inorganic material.

5. The electrode sheet according to claim 4, characterized in that the mass content of the color former in the first insulating layer is 2% to 20%, the mass content of the adhesive is 8% to 40%, and the mass content of the ceramic filler is 55% to 88%.

6. The electrode sheet according to claim 5, characterized in that the mass content of the color former in the first insulating layer is 2.5% to 10%, and the mass content of the adhesive is 10% to 35%.

7. the color former includes at least one of titanium chrome brown, titanium nickel yellow, bismuth vanadate, chromium oxide green, cobalt green, cobalt blue, Prussian blue, cadmium red, cadmium yellow, lithopone, carbon black, iron oxide red, and iron oxide yellow; the adhesive comprises at least one of polyvinylidene fluoride, polyimide, polyphenylene sulfide, polyarylsulfone, polyether chloride, polyacrylonitrile, polyvinyl alcohol, ethylene acrylic acid copolymer, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, and polyacrylic acid; 5. The electrode sheet according to claim 4, wherein the ceramic filler contains at least one of aluminum oxide, boehmite, titanium dioxide, zirconium dioxide, zinc oxide, barium sulfate, boron nitride, aluminum nitride, and magnesium nitride.

8. The average particle size of the color former is d １ and the average particle size of the ceramic filler is d ２ Then, the above d １ and the above d ２ However, 0.25≦d １ / d ２ 5. The electrode sheet according to claim 4, wherein the thickness satisfies ≦6.

9. The above d １ and the above d ２ However, 0.8≦d １ / d ２ 9. The electrode sheet according to claim 8, wherein the ratio satisfies ≦4.

10. 5. The electrode sheet according to claim 4, wherein the chromaticity of the color former in a standard electrolyte solution is 0 degrees to 20 degrees, the standard electrolyte solution contains an organic solvent and a lithium salt, the organic solvent contains ethyl propyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, and fluorinated ethylene carbonate in a volume ratio of 40:20:25:5:10, the lithium salt is a lithium salt obtained by mixing lithium hexafluorophosphate and lithium difluorooxalate borate in a mass ratio of 97:3, and a concentration of the lithium salt in the electrolyte solution is 1 mol / L.

11. The electrode sheet according to any one of claims 1 to 10, wherein the electrode sheet is a positive electrode sheet.

12. 11. A battery comprising an electrode assembly, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet, and a separator placed between the positive electrode sheet and the negative electrode sheet, wherein at least one of the positive electrode sheet and the negative electrode sheet employs the electrode sheet according to any one of claims 1 to 10, and the first insulating layer is located on the side of the electrode sheet facing a central hole of the electrode assembly.

13. a housing having an open side for receiving the electrode assembly, the housing including an end wall and a side wall surrounding the end wall; an electrode terminal attached through the end wall; a cover plate that covers the opening; The battery of claim 12 further comprising:

14. 14. The battery of claim 13, wherein the battery is a cylindrical battery.

15. An electronic device comprising the battery according to any one of claims 12 to 14.

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