Electrode sheet, secondary battery, and electronic device

Abstract

The present invention discloses an electrode plate, a secondary battery and an electronic device, which can at least avoid the phenomenon of compatibilization and bulging between the active material layer and the insulation layer of the electrode plate, thereby improving the quality of the electrode plate.SOLUTION: The present disclosure discloses an electrode plate, a secondary battery and an electronic device, the electrode plate includes a current collector, a conductive layer, an insulation layer disposed on a same surface of the current collector and spaced apart from the conductive layer in a first direction, and an active material layer coated on the conductive layer, in the first direction, an edge of the active material layer facing the insulation layer extends beyond the conductive layer, and there is a preset distance between the edge of the active material layer and the insulation layer.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to the technical field of batteries, and more particularly to electrode sheets, secondary batteries, and electronic devices. [Background technology]

[0002] In the field of new energy power batteries, the application of secondary batteries is becoming increasingly widespread, for example, secondary batteries (e.g., lithium-ion batteries) can be applied to electronic devices such as vehicles, power storage, mobile phones, tablet computers, wearable devices, mobile power supplies, electronic cigarettes, digital products, power tools, power equipment, and power storage devices. Secondary batteries usually include a case and an electrode assembly, and the electrode assembly includes a positive electrode sheet, a first separator, a negative electrode sheet, and a second separator, which are sequentially stacked together to produce a wound electrode assembly or a stacked electrode assembly, which is then sealed in a case. Summary of the Invention [Problem to be solved by the invention]

[0003] In response to the problems in the related art, the present invention proposes an electrode sheet, a secondary battery, and an electronic device, which at least makes the active material layer and the insulating layer of the electrode sheet compatible with each other, can avoid the occurrence of the phenomenon of bulging, and improves the quality of the electrode sheet. [Means for solving the problem]

[0004] According to one aspect of the present invention, there is provided an electrode sheet comprising: a current collector; a conductive layer; an insulating layer disposed on the same surface of the current collector at a distance from the conductive layer along a first direction; and an active material layer coated on the conductive layer, wherein, in the first direction, an edge of the active material layer facing the insulating layer extends beyond the conductive layer, and there is a predetermined distance between the edge of the active material layer and the insulating layer.

[0005] In the above technical solution, by covering the edge of the conductive layer close to the insulating layer with the active material layer, the edge of the active material layer close to the insulating layer is directly coated on the current collector. Therefore, when monitoring the dimensions of the active material layer during the coating period of the active material layer, it is not necessary to grip the edge of the active material layer depending on the active material layer and the conductive layer with usually small color differences. Thus, the edge of the active material layer can be effectively gripped to leave a preset interval between the active material layer and the insulating layer, effectively avoiding the phenomenon that the slurry of the active material layer is compatible with the insulating layer and bulging occurs, and improving the quality of the electrode sheet.

[0006] In some embodiments, the distance between the insulating layer and the conductive layer is L mm, satisfying x / 2 - 0.5 mm < L mm < x / 2 + 0.5 mm, where x represents the width of the conductive layer coated on the current collector in the first direction, and the unit is mm.

[0007] In some embodiments, the dimensional range of the interval in the first direction is from 1 / 3 L mm to 2 / 3 L mm.

[0008] In some embodiments, the thickness of the insulating layer is t μm, satisfying T μm / t μm > 2, where T μm represents the thickness of the active material layer.

[0009] In some embodiments, the current collector includes a tab protruding from the active material layer in the first direction. The tab has a height in the first direction, and the insulating layer has a width in the first direction, where the width is less than 1 / 3 of the height.

[0010] In some embodiments, the color of the active material layer is different from that of the current collector, or the distinguishable color difference between the active material layer and the current collector is greater than the distinguishable color difference between the active material layer and the conductive layer.

[0011] In some embodiments, the active material layer includes a flat portion and a thin portion connected to one end of the flat portion along the first direction, where the thin portion is located at one end close to the insulating layer of the flat portion.

[0012] In some embodiments, the insulating layer and the conductive layer are already formed before forming the active material layer, the current collector is made of aluminum, and the active material layer includes a phosphate positive electrode material.

[0013] According to another aspect of the present invention, there is provided a secondary battery including a case having an opening for accommodating an electrode assembly, and an end cap for sealing the opening, wherein the electrode assembly includes the electrode sheet.

[0014] According to yet another aspect of the present invention, there is provided an electronic device including the secondary battery. [Effects of the Invention]

[0015] The beneficial effects of the present invention include: By covering the edge of the conductive layer closest to the insulating layer with an active material layer and providing a gap between the active material layer and the insulating layer, the active material layer slurry becomes compatible with the insulating layer, effectively preventing bulging and improving the quality of the electrode sheet. The active material layer can be formed by coating, and the edge of the active material layer closest to the insulating layer is the edge away from the flat portion of the thin portion of the active material layer. Because there is a large color difference between the active material layer and the underlying current collector, the edge of the active material layer can be accurately grasped and monitored using a CCD camera during the active material layer coating process, thereby improving the control accuracy of the coating process and preventing misalignment of the active material layer. In particular, even if the conductive layer is misaligned, the active material layer can be prevented from becoming misaligned. [Brief explanation of the drawings]

[0016] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention, and those skilled in the art can also obtain other accompanying drawings based on these accompanying drawings without requiring creative work.

[0017] [Figure 1] 1 shows a schematic diagram of an electronic device, for example a vehicle. [Figure 2] 1 shows a three-dimensional view of a secondary battery, taking a cylindrical battery as an example, according to an embodiment of the present invention. [Figure 3] 1 shows a cross-sectional view of a secondary battery, taking a cylindrical battery as an example, according to an embodiment of the present invention. [Figure 4] 1 shows a three-dimensional view of a secondary battery, taking a prismatic battery as an example, according to another embodiment of the present invention. [Figure 5] 1 shows a three-dimensional view of an electrode assembly of a secondary battery, taking a prismatic battery as an example, according to another embodiment of the present invention. [Figure 6] FIG. 1 is a structural schematic diagram of an electrode sheet of a conventional secondary battery. [Figure 7] 1 is a cross-sectional schematic view of an electrode sheet according to an embodiment of the present invention. [Figure 8] FIG. 8 is a schematic overhead view of the electrode sheet shown in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0018] The following clearly and completely describes the technical solutions in the embodiments of the present invention in combination with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention belong to the protection scope of the present invention.

[0019] The embodiments of the present invention are described in detail below. Throughout the specification of the present invention, identical or similar components and components having identical or similar functions are designated by similar reference numerals in the drawings. The embodiments related to the accompanying drawings described herein are of explanatory and illustrative nature and are used to provide a basic understanding of the present invention. The embodiments of the present invention should not be construed as limitations of the present invention.

[0020] As used herein, the terms "approximately," "essentially," "substantially," and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the term may refer to instances in which the event or circumstance occurs exactly as well as instances in which the event or circumstance occurs very approximately.

[0021] In this specification, unless otherwise specified or limited, relative terms such as "center," "longitudinal," "lateral," "front," "rear," "right," "left," "inner," "outer," "lower," "higher," "horizontal," "vertical," "higher," "lower," "upper," "lower," "top," "bottom," and derivative terms thereof (e.g., "horizontally," "below," "upper," etc.) should be construed as referring to the orientations described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require the invention to be constructed or operated in a particular orientation.

[0022] For convenience of description, terms such as "first," "second," "third," etc. may be used in the text to distinguish between different elements in a single figure or series of figures. The terms "first," "second," "third," etc. are not intended to describe corresponding elements. Furthermore, where not inconsistent, embodiments of the present invention and features of the embodiments may be combined with each other. The present invention will now be described in detail in conjunction with the accompanying drawings.

[0023] 1 is a schematic diagram of an electronic device, taking a vehicle 1000 as an example. For convenience of explanation, the following embodiments will be described with reference to FIG. 1, taking the vehicle 1000 as an example of the electronic device. However, it should be understood that the electronic device provided by the present invention is not limited to a vehicle, and the electronic device may be a vehicle, a mobile phone, a portable device, a laptop, a boat, a spacecraft, an electric toy, an electric tool, etc.

[0024] A battery pack 1002 may be installed inside the vehicle 1000, and the battery pack 1002 may be installed at the bottom (as shown in FIG. 1 ), head, or tail of the vehicle body 1001, or any other suitable location. The battery pack 1002 may be used to supply power to the vehicle 1000; for example, the battery pack 1002 may be used as an operating power source or a driving power source for the vehicle 1000. The battery pack 1002 may include a plurality of secondary batteries (such as the secondary battery 100A described with reference to FIGS. 2 and 3 or the secondary battery 100B described with reference to FIGS. 4 and 5) and a box assembly that houses the plurality of secondary batteries.

[0025] It should be understood that the secondary battery of the present invention may have various shapes, such as a cylindrical shape, a flat shape, a rectangular parallelepiped shape, or other shapes, and the embodiments of the present invention are not limited thereto. On the other hand, the secondary battery of the present invention may be a lithium ion battery, a lithium sulfur battery, a sodium lithium ion battery, a sodium ion battery, and the like, and the embodiments of the present invention are not limited thereto.

[0026] FIG. 2 shows a three-dimensional view of a secondary battery 100A according to an embodiment of the present invention. In the embodiment shown in FIG. 2, the secondary battery 100A is shown as a cylindrical battery. FIG. 3 shows a cross-sectional view of the secondary battery 100A according to an embodiment of the present invention. As shown in FIGS. 2 and 3, the secondary battery 100A may include an electrode assembly 120, an electrolyte, a case 200, and an end cap 202. The case 200 may have an opening 205 at one end in the height direction (direction h), and the end cap 202 is disposed in the opening 205 to seal the chamber. The case 200 and the end cap 202 are components that collectively accommodate the electrode assembly 120 and the electrolyte. The case 200 may be made of any of a variety of usable materials, such as copper, iron, aluminum, steel, and aluminum alloys. The case 200 may have a cylindrical shape and define a chamber, within which the electrode assembly 120 is disposed. The diameter of the case 200 may be determined based on the specific dimensions of the electrode assembly 120, such as 18 mm, 21 mm, 46 mm, etc. In some embodiments, the secondary battery 100A may be a 4680 cylindrical battery (diameter 46 mm, height 80 mm), the secondary battery 100A may be a 4695 cylindrical battery (diameter 46 mm, height 95 mm), or the secondary battery 100A may be a 46120 cylindrical battery (diameter 46 mm, height 120 mm).

[0027] The case 200 may be connected to the negative electrode of the electrode assembly 120. The secondary battery 100A may further have a terminal 208 at one end relative to the end cap 202, and the terminal 208 may be connected to the positive electrode of the electrode assembly 120. It should be understood that an insulating compound is present between the terminal 208 and the case 200 to prevent short-circuiting of the battery.

[0028] In some embodiments, the electrode assembly 120 may include a first electrode sheet, a first separator, a second electrode sheet, and a second separator, which are stacked in sequence. In this embodiment, the stacked first electrode sheet, first separator, second electrode sheet, and second separator may be wound to form a cylindrical electrode assembly 120. The electrode assembly 120 has a first tab and a second tab at each end of the height direction h of the secondary battery 100. An electrolyte may be located between the first electrode sheet, the first separator, the second electrode sheet, and the second separator. In some embodiments, the first electrode sheet is a positive electrode sheet, and the second electrode sheet is a negative electrode sheet. In some embodiments, the positive electrode tab faces the end wall 111 and is electrically connected to the terminal 208, making the terminal 208 positively charged, and the negative electrode tab faces the opening 205, and the case 200 is electrically connected to the negative electrode tab, making the case 200 negatively charged.

[0029] FIG. 4 shows a three-dimensional view of a secondary battery 100B, which is a prismatic battery according to another embodiment of the present invention. FIG. 5 shows a three-dimensional view of an electrode assembly of the secondary battery 100B, which is a prismatic battery according to another embodiment of the present invention. In FIGS. 4 and 5, the secondary battery 100B is a prismatic battery. In combination with those shown in FIGS. 2 and 3, the secondary battery 100B may include an electrode assembly 220, an electrolyte, a case 300, and a cover plate assembly 302. The case 300 may have a flattened rectangular parallelepiped shape. The case 300 may have an opening (not shown) at one end in the height direction h, and the cover plate assembly 302 is disposed in the opening. A first terminal 311, a second terminal 312, and an explosion-proof valve 313 are disposed on the cover plate assembly 302. In some embodiments, the first terminal 311 and the second terminal 312 serve as a positive terminal and a negative terminal, respectively.

[0030] In some embodiments, the electrode assembly 220 may include a first electrode sheet, a first separator, a second electrode sheet, and a second separator, which are stacked in sequence. In some embodiments, the first electrode sheet is a positive electrode sheet, and the second electrode sheet is a negative electrode sheet. An electrolyte may be located between the first electrode sheet, the first separator, the second electrode sheet, and the second separator. In this embodiment, the stacked first electrode sheet, the first separator, the second electrode sheet, and the second separator may be wound to form the electrode assembly 220 in the shape of a flat rectangular parallelepiped. The electrode assembly 220 has a first tab 221 and a second tab 222 installed at the same end in the height direction h of the secondary battery 100B. In some embodiments, the first tab 221 and the second tab 222 face the cover plate assembly 302, and the first tab 221 and the second tab 222 are electrically connected to the corresponding first terminal 311 and the second terminal 312, respectively, making the first terminal 311 and the second terminal 312 positive or negative, respectively.

[0031] The positive electrode sheet in the secondary battery (e.g., secondary battery 100A, 100B) may include a positive electrode current collector and a positive electrode active material layer coated on both surfaces of the positive electrode current collector. The portion of the positive electrode current collector not coated with the positive electrode active material layer constitutes a positive electrode tab. The negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer coated on both surfaces of the negative electrode current collector. The portion of the negative electrode current collector not coated with the negative electrode active material layer constitutes a negative electrode tab. Taking a lithium-ion battery as an example, the positive electrode current collector may be made of aluminum, and the positive electrode active material layer may include a positive electrode active material, which may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide, or the like. The negative electrode current collector may be made of copper, and the negative electrode active material layer may include a negative electrode active material, which may be carbon, silicon, or the like. In some embodiments, the first separator and the second separator may be made of a material such as PP (polypropylene) or PE (polyethylene), etc. The current collector is made of aluminum, and the active material layer includes a phosphate positive electrode material.

[0032] Furthermore, in order to prevent short circuits between the positive electrode sheet and the negative electrode sheet, an insulating material is usually applied near the edge of the positive electrode active material layer of the positive electrode sheet or the negative electrode active material layer of the negative electrode sheet to form an insulating layer.

[0033] The structure of a conventional positive electrode sheet or negative electrode sheet (hereinafter, collectively referred to as electrode sheet) for a secondary battery is shown in FIG. 6. As shown in FIG. 6, in the process of manufacturing an electrode sheet 10, a current collector 12 having a conductive layer 14 formed thereon is first provided, and then an insulating layer 16 and an active material layer 18 are simultaneously applied. After the insulating layer 16 and the active material layer 18 are applied, the sheet is cut along line Lc to obtain the electrode sheet 10. The obtained electrode sheet 10 may include a current collector 12, a conductive layer 14 and an insulating layer 16 formed on the current collector 12 at a distance from each other, and an active material layer 18 formed on the conductive layer 14. The active material layer 18 is located entirely on the conductive layer 14, and the dimension of the conductive layer 14 in the first direction X is larger than that of the active material layer 18.

[0034] In the above-described manufacturing process of the electrode sheet 10, the coating of the insulating layer 16 and the coating of the active material layer 18 are performed simultaneously, and after the slurries for the insulating layer 16 and the active material layer 18 are attached to the current collector 12, the difference in interfacial tension is large, so the two slurries are likely to become mismatched, causing bulging, and the quality of the electrode sheet may not meet the design requirements. Furthermore, due to the precision of the processing equipment, when the conductive layer 14 is applied to the current collector 12, there is likely to be some misalignment between the two sides of the conductive layer 14 in the first direction X, which will also cause misalignment in the active material layer 18 applied to the conductive layer 14. Furthermore, in conventional electrode sheets 10, the gap G1 between the active material layer 18 and the insulating layer 16 is the conductive layer 14 and the blank current collector 12, and the dimensions of the conductive layer 14 are larger than those of the active material layer 18, and the color difference between the conductive layer 14 and the active material layer 18 is usually small. Therefore, conventional image monitoring devices (e.g., CCD cameras) cannot effectively grasp the edge of the active material layer 18, and further cannot effectively monitor the dimensions of the active material layer 18 and the gap G1 between the active material layer 18 and the insulating layer 16.

[0035] FIG. 7 is a cross-sectional schematic diagram of an electrode sheet 20 according to an embodiment of the present invention. FIG. 8 is a top view schematic diagram of the electrode sheet 20 shown in FIG. Combining FIGS. 7 and 8, the electrode sheet 20 may include a current collector 12, a conductive layer 14, and an insulating layer 16. The insulating layer 16 and the conductive layer 14 are disposed on the same surface 12s of the current collector 12 with a gap therebetween along the first direction X. The conductive layer 14 and the insulating layer 16 may be directly coated on the surface 12s of the current collector 12. The current collector 12 is a component that can be used to collect current. Its function is to collect the current newly generated by the active materials in the battery to form a larger current and output it to the outside. Therefore, the current collector 12 is generally made of a metal material with as low an internal resistance as possible, such as aluminum or copper. The current collector 12 is generally a metal foil. In some embodiments, when the electrode sheet 20 is a positive electrode sheet, the current collector 12 may be aluminum foil. When the electrode sheet 20 is a negative electrode sheet, the current collector 12 may be copper foil.

[0036] The electrode sheet 20 may further include an active material layer 18, which covers the conductive layer 14. In the first direction X, an edge 18e of the active material layer 18 facing the insulating layer 16 extends beyond the conductive layer 14. The portion of the active material layer 18 that extends beyond the conductive layer 14 may directly cover the current collector 12. There is a predetermined gap G2 between the edge 18e of the active material layer 18 and the insulating layer 16.

[0037] In the above technical solution, the edge of the conductive layer 14 that is closest to the insulating layer 16 is covered with the active material layer 18, so that the edge of the active material layer 18 that is closest to the insulating layer 16 is directly applied to the current collector 12. Therefore, during the application of the active material layer 18 (for example, when monitoring the dimensions of the active material layer 18 with a CCD (charge coupled device) camera), it is not necessary to rely on the active material layer 18 and the conductive layer 14, which usually have a small color difference, to hold the edge of the active material layer 18. This allows the edge of the active material layer 18 to be effectively held. Furthermore, by providing a predetermined gap G2 between the active material layer 18 and the insulating layer 16, the slurry for the active material layer 18 becomes miscible with the insulating layer 16, effectively preventing bulging and improving the quality of the electrode sheet.

[0038] In some embodiments, the insulating layer and the conductive layer are already formed before the active material layer is formed. Specifically, in the process of forming the electrode sheet 20, the conductive layer 14 and the insulating layer 16 may already be applied before the active material layer 18 is applied. Specifically, the process of forming the electrode sheet 20 may include: applying the conductive layer 14 and the insulating layer 16 on the current collector 12; applying an active material layer slurry on the conductive layer 14 on the current collector 12 after the conductive layer 14 and the insulating layer 16 are formed; and forming the active material layer 18 after the active material layer slurry has dried. In this process, the insulating layer 16 is formed in advance, and the insulating layer 16 and the active material layer 18 are not applied simultaneously. Therefore, when applying the active material layer 18, the predetermined gap G2 between the active material layer 18 and the insulating layer 16 can be controlled simply by monitoring the casting of the edge of the active material layer 18. This allows for effective control of the dimensions of the active material layer 18 and the gap G2, and effectively avoids the problem of the slurry for the active material layer 18 and the slurry for the insulating layer 16 being compatible with each other and prone to bulging.

[0039] The conductive layer 14 includes a conductive agent and a binder, the conductive agent containing any one or more selected from the group consisting of acetylene black, carbon fiber, conductive carbon black, conductive graphite, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene nanosheets, graphene oxide nanosheets, and fine graphite powder, and the binder containing any one or more selected from the group consisting of PVDF (polyvinylidene fluoride), polyacrylonitrile, styrene butadiene rubber, polyvinyl alcohol, gum arabic, xanthan gum, and polyacrylate.

[0040] Insulating layer 16 may contain an organic material. In some embodiments, insulating layer 16 contains one or a mixture of two or more selected from the group consisting of butyl acrylate, styrene, acrylic acid, hydroxyethyl acrylate, and styrene-butadiene rubber (SBR), and the optional material for the insulating layer may be an aqueous solution dispersed in water in an amount of 10 to 90 weight percent. In other embodiments in which insulating layer 16 contains an organic material, insulating layer 16 includes an insulating material and a binder, wherein the binder includes at least one of polyvinylidene fluoride, polyurethane, sodium polyacrylate, styrene-butadiene rubber, polyetherimide, carboxymethyl cellulose, and acrylate, and the insulating material includes at least one of Al2O3, BaSO4, CaSiO3, γ-AlOOH, CaSiO4, and polytetrafluoroethylene.

[0041] In some embodiments, the electrode sheet 20 is a positive electrode sheet. In embodiments where the electrode sheet 20 is a positive electrode sheet, the material of the current collector 12 may be aluminum. The active material layer 18 of the positive electrode sheet is preferably a phosphate material, because this type of phosphate material is more likely to shrink due to surface tension with the insulating layer. The design of the above-mentioned predetermined gap G2 of the present invention can avoid compatibility between the active material layer of the positive electrode sheet and the insulating layer, thereby solving this problem.

[0042] Specifically, the active material layer 18 may include a flat portion 181 and a thin portion 182 connected to one end of the flat portion 181 along the first direction X, and the thin portion 182 is located at one end of the flat portion 181 that is adjacent to the insulating layer 16. The edge 18e of the active material layer 18 that is adjacent to the insulating layer 16 is the edge of the thin portion 182 that is away from the flat portion 181. That is, the edge 18e of the active material layer 18 that is adjacent to the insulating layer 16 is the edge of the thin portion 182 that is formed by the coating process. In this manner, a gap may be formed between the thin portion 182 and the insulating layer 16, which more safely and effectively facilitates compatibility between the slurry for the active material layer 18 and the slurry for the insulating layer 16 and avoids the problem of bulging.

[0043] In the illustrated embodiment, the edge 14e of the conductive layer 14 adjacent to the insulating layer 16 is covered by the thinned portion 182. In other embodiments, the edge 14e of the conductive layer 14 may be covered by the flat portion 181, and the thinned portion 182 may be located in the space between the conductive layer 14 and the insulating layer 16.

[0044] In some embodiments, the active material layer 18 has a different color than the current collector 12. It should be understood that, in the present invention, "different color" refers to a difference in color that can be accurately identified by a CCD camera for edge grasping. For example, the active material layer 18 may be typically black, and the current collector 12 may be typically white. Because of the significant color difference between the active material layer 18 and the underlying current collector 12, the edge 18e of the active material layer 18 can be accurately grasped and monitored by a CCD camera during application of the active material layer 18, thereby improving control of the application process and preventing misalignment of the active material layer 18.

[0045] In some embodiments, the distinguishable color difference between the active material layer 18 and the current collector 12 is greater than the distinguishable color difference between the active material layer 18 and the conductive layer 14. For example, the colors of the active material layer 18 and the conductive layer 14 are usually both black. As described above with reference to FIG. 6, when the color difference between the active material layer 18 and the conductive layer 14 is small, it is difficult to grip the edge 18e when applying the active material layer 18. The present invention extends the edge 18e of the active material layer 18 onto the current collector 12 with a greater distinguishable color difference, so that the edge 18e of the active material layer 18 is directly applied onto the current collector 12. Therefore, it is not necessary to grip the edge 18e of the active material layer 18 depending on the active material layer 18 and the conductive layer 14 with a usually small color difference. Thus, the edge 18e can be effectively gripped, and the control accuracy of the coating process of the active material layer 18 is improved. Since the control accuracy of the coating of the active material layer 18 is improved, the occurrence of misalignment of the active material layer 18 can be avoided. In particular, even when the conductive layer 14 is misaligned, the active material layer 18 can be controlled so as not to be misaligned.

[0046] In some embodiments, the conductive layer 14 may be a carbon coating layer. In some embodiments, the thickness bμm of the conductive layer 14 may satisfy 0 < bμm ≤ 1.5μm. When the thickness bμm of the conductive layer 14 is greater than 1.5μm, the overall thickness of the active material layer 18 may decrease, and thereby the energy density of the battery may decrease.

[0047] In some embodiments, the distance Lmm between the insulating layer 16 and the conductive layer 14 satisfies x / 2 - 0.5mm < Lmm < x / 2 + 0.5mm, where x represents the width in the first direction X of the conductive layer 14 coated on the current collector 12, and the unit is mm. When the distance Lmm between the conductive layer 14 and the insulating layer 16 is too small, it becomes difficult to apply the edge of the active material layer 18 between the conductive layer 14 and the insulating layer 16. When the distance Lmm between the conductive layer 14 and the insulating layer 16 is too large, the exposed portion of the current collector 12 may become too large, resulting in a waste of the utilization rate of the current collector.

[0048] In some embodiments, the dimension range of the gap G2 between the active material layer 18 and the insulating layer 16 in the first direction X is 1 / 3 to 2 / 3 of the distance L mm (i.e., 1 / 3L mm to 2 / 3L mm). This range of the gap G2 ensures that the edge of the active material layer 18 is coated on the current collector 12 within the process tolerance of the coating device, and also maintains the gap G2 with the insulating layer 16. In some embodiments, the coating width of the active material layer 18 on the current collector 12 in the first direction X is d mm, and the width d mm may be equal to the total width of the active material layer 18 minus x. In some embodiments, 0 <dmm≦5mmである。

[0049] In some embodiments, the thickness of the insulating layer 16 is t μm, the thickness of the active material layer 18 is T μm, and the thickness of the insulating layer 16 satisfies T μm / t μm > 2. If the insulating layer 16 is too thin, the insulating layer 16 may not be able to provide insulation protection. If the insulating layer 16 is too thick, the portion of the current collector 12 covered by the insulating layer 16 may be difficult to flex, which is unfavorable for applying the electrode sheet to, for example, a cylindrical battery. On the other hand, if the active material layer 18 is too thin, the energy density of the battery may be reduced. By rationally setting the thicknesses of the insulating layer 16 and the active material layer 18, good results can be achieved in all aspects: the insulating layer 16 provides insulation protection, the current collector 12 is easy to flex, and the energy density of the battery is ensured.

[0050] In some embodiments, current collector 12 may include a tab 125 protruding from active material layer 18 in first direction X, tab 125 having a height H1 in first direction X, and insulating layer 16 having a width W1 in first direction X, where width W1 may be less than 1 / 3 of height H1. A gap G2 may be effectively preset between active material layer 18 and insulating layer 16, thereby achieving a wide application of insulating layer 16, and width W1 of insulating layer 16 may be increased to 1 / 3 of height H1 of tab 125.

[0051] In some embodiments, when the electrode sheet 20 is an electrode sheet for a cylindrical battery, the first direction X may correspond to the height direction h of the cylindrical battery in Figure 2. In some embodiments, when the electrode sheet 20 is an electrode sheet for a prismatic battery, the first direction X may correspond to the height direction h of the prismatic battery in Figure 4.

[0052] An embodiment of the present invention further provides a secondary battery (see, for example, secondary battery 100A shown in FIGS. 2 and 3 and secondary battery 100B shown in FIGS. 4 and 5), which may include a case having an opening for accommodating an electrode assembly, and an end cap for sealing the opening. The electrode assembly includes the electrode sheet 20 in the embodiment.

[0053] The embodiment of the present invention further provides an electronic device, which may include the secondary battery in the above embodiment. The electronic device may be, for example, the vehicle 1000 shown in FIG.

[0054] The above-described are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should all be included in the protection scope of the present invention. [Industrial Applicability]

[0055] The present invention relates to the technical field of batteries, and more particularly to electrode sheets, secondary batteries, and electronic devices. [Explanation of symbols]

[0056] 10, 20 Electrode sheet 12 Current collector 12s surface 14 Conductive layer 14e Edge 16 Insulating layer 18 Active material layer 18e Edge 181 Flat area 182 Thin-walled section 100A, 100B secondary battery 120 Electrode Assembly 125 tabs 200 cases 202 End Cap 205 Aperture 208 terminals 220 Electrode Assembly 221 Tab 1 222 Second Tab 300 cases 302 Cover Plate Assembly 311 1st terminal 312 2nd terminal 313 Explosion-proof valve 1000 vehicles 1001 Body 1002 Battery Pack G1 interval G2 interval H1 Height L distance T Thickness W1 width X 1st direction b Thickness d width h Height direction t is the thickness of the insulating layer Lc cut line

Claims

1. A current collector; a conductive layer; an insulating layer disposed on the same surface of the current collector and spaced apart from the conductive layer along the first direction; an active material layer coated on the conductive layer, An electrode sheet, characterized in that in the first direction, an edge of the active material layer toward the insulating layer extends beyond the conductive layer, and there is a predetermined gap between the edge of the active material layer and the insulating layer.

2. 2. The electrode sheet according to claim 1, wherein a distance between the insulating layer and the conductive layer is L mm, and x / 2-0.5 mm<L mm<x / 2+0.5 mm is satisfied, where x represents a width in the first direction of the conductive layer coated on the current collector, and the unit is mm.

3. The electrode sheet according to claim 2 , wherein the gap has a dimension ranging from 1 / 3 L mm to 2 / 3 L mm in the first direction.

4. The electrode sheet according to claim 1 , wherein the insulating layer has a thickness of t μm, and satisfies T μm / t μm>2, where T μm represents the thickness of the active material layer.

5. the current collector includes a tab protruding from the active material layer in the first direction, the tab having a height in the first direction; The electrode sheet of claim 1 , wherein the insulating layer has a width in the first direction, wherein the width is less than one-third of the height.

6. The active material layer has a different color from the current collector, or 2. The electrode sheet according to claim 1, wherein the distinguishable color difference between the active material layer and the current collector is greater than the distinguishable color difference between the active material layer and the conductive layer.

7. 2. The electrode sheet according to claim 1, wherein the active material layer includes a flat portion and a thin portion connected to one end of the flat portion along a first direction, and wherein the thin portion is located at one end of the flat portion that is closest to the insulating layer.

8. 2. The electrode sheet according to claim 1, wherein the insulating layer and the conductive layer are already formed before the active material layer is formed, the current collector is made of aluminum, and the active material layer contains a phosphate positive electrode material.

9. a case having an opening for housing the electrode assembly; an end cap for sealing the opening; A secondary battery, wherein the electrode assembly comprises the electrode sheet according to claim 1 .

10. An electronic device comprising the secondary battery according to claim 9.

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