Pole piece, secondary battery and electronic device

Abstract

The utility model discloses a pole piece, a secondary battery and an electronic device. The pole piece comprises a current collector; a conductive layer; the insulating layer and the conductive layer are arranged on the same surface of the current collector at intervals along a first direction; the conductive layer is covered with the active material layer, in the first direction, the edge, facing the insulating layer, of the active material layer exceeds the conductive layer, and a preset interval is formed between the edge of the active material layer and the insulating layer. According to the technical scheme, at least the phenomena of mutual dissolution and edge bulging of the active material layer and the insulating layer of the pole piece can be avoided, and the quality of the pole piece is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and more specifically, to a pole piece, a secondary battery and an electronic device. Background Art

[0002] In the field of new energy power batteries, secondary batteries are increasingly being used in a wide range of applications. For example, secondary batteries (such as lithium-ion batteries) can be applied to electronic devices such as cars, energy storage, mobile phones, tablets, wearable devices, mobile power supplies, e-cigarettes, digital products, power tools, power devices, and energy storage devices. A secondary battery typically includes a housing and an electrode assembly. The electrode assembly includes a positive electrode sheet, a first separator, a negative electrode sheet, and a second separator. These are stacked in sequence to form a wound electrode assembly or a laminated electrode assembly, which is then encapsulated in a housing. Utility Model Content

[0003] In response to the problems in the related art, the present invention proposes a pole piece, a secondary battery and an electronic device, which can at least avoid the mutual dissolution and bulging of the active material layer and the insulating layer of the pole piece, thereby improving the quality of the pole piece.

[0004] According to one aspect of the present invention, a pole piece is provided, comprising: a current collector; a conductive layer; an insulating layer, arranged on the same surface of the current collector and spaced apart from the conductive layer along a first direction; and an active material layer, covering the conductive layer, wherein, in the first direction, the edge of the active material layer toward the insulating layer extends beyond the conductive layer, and a preset interval is set between the edge of the active material layer and the insulating layer.

[0005] In the above technical solution, the active material layer covers the edge of the conductive layer near the insulating layer, allowing the edge of the active material layer near the insulating layer to be directly coated on the current collector. Therefore, when monitoring the size of the active material layer during coating, there is no need to rely on the active material layer and the conductive layer, which generally have a smaller color difference, to capture the edge of the active material layer. This allows the edge of the active material layer to be effectively captured while a predetermined gap is set between the active material layer and the insulating layer. This effectively prevents the active material layer slurry from dissolving into the insulating layer and causing bulging of the edge, thereby improving the quality of the electrode.

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

[0007] In some embodiments, the spacing has a dimension in the first direction ranging from 1 / 3 Lmm to 2 / 3 Lmm.

[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 a first direction, the tab has a height in the first direction, and the insulating layer has a width in the first direction, wherein the width is less than 1 / 3 of the height.

[0010] In some embodiments, the active material layer has a different color than the current collector, or,

[0011] The recognizable color difference between the active material layer and the current collector is greater than the recognizable color difference between the active material layer and the conductive layer.

[0012] In some embodiments, the active material layer includes a straight region and a thinned region connected to one end of the straight region along the first direction, wherein the thinned region is located at one end of the straight region close to the insulating layer.

[0013] In some embodiments, the insulating layer and the conductive layer are formed before the active material layer is formed.

[0014] According to another aspect of the present invention, a secondary battery is provided, comprising: a housing having an opening for accommodating an electrode assembly; and an end cover for closing the opening, wherein the electrode assembly comprises the aforementioned electrode sheet.

[0015] According to another aspect of the present invention, an electronic device is provided. The electronic device includes the aforementioned secondary battery.

[0016] The beneficial effects of this application include:

[0017] By covering the edge of the conductive layer near the insulating layer with the active material layer and providing a gap between the active material layer and the insulating layer, the phenomenon of the active material layer slurry dissolving with the insulating layer and bulging the edge can be effectively avoided, thereby improving the quality of the electrode. The active material layer can be formed by coating, and the edge of the active material layer near the insulating layer is the edge of the thinned area of ​​the active material layer away from the straight area. Since the color difference between the active material layer and the current collector below it is large, the edge of the active material layer can be accurately captured and monitored by a CCD camera during the coating of the active material layer, thereby improving the control accuracy of the coating process and avoiding the misalignment of the active material layer. In particular, even if the conductive layer is misaligned, the active material layer can be controlled not to be misaligned. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of an electronic device is shown, taking a vehicle as an example.

[0020] Figure 2 A perspective view of a secondary battery taking a cylindrical battery as an example according to an embodiment of the present application is shown.

[0021] Figure 3 A cross-sectional view of a secondary battery using a cylindrical battery as an example according to an embodiment of the present application is shown.

[0022] Figure 4 A perspective view of a secondary battery taking a square-shell battery as an example according to another embodiment of the present application is shown.

[0023] Figure 5 A perspective view of an electrode assembly of a secondary battery taking a square-cased battery as an example according to another embodiment of the present application is shown.

[0024] Figure 6 It is a structural schematic diagram of an existing secondary battery electrode.

[0025] Figure 7 Schematic cross-sectional view of a pole piece according to an embodiment of the present application.

[0026] Figure 8 yes Figure 7 Schematic top view of the pole piece shown. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0028] The embodiments of the present application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are represented by similar reference numerals. The embodiments described herein with respect to the accompanying drawings are illustrative and diagrammatic and are intended to provide a basic understanding of the present application. The embodiments of the present application should not be construed as limiting the present application.

[0029] As used herein, the terms "substantially," "substantially," "essentially," and "about" are used to describe and illustrate small variations. When used in conjunction with an event or circumstance, the terms may refer to instances where the event or circumstance occurred precisely as well as instances where the event or circumstance occurred very approximately.

[0030] In this specification, unless otherwise specified or limited, relative terms such as "central", "longitudinal", "lateral", "front", "rear", "right", "left", "inner", "outer", "lower", "higher", "horizontal", "vertical", "above", "below", "above", "below", "top", "bottom" and their derivatives (such as "horizontally", "downwardly", "upwardly", etc.) should be interpreted as referring to the directions described in the discussion or depicted in the drawings. These relative terms are only used for convenience of description and do not require that the present application be constructed or operated in a specific orientation.

[0031] For ease of description, "first," "second," "third," and the like may be used herein to distinguish different components within a figure or a series of figures. "First," "second," "third," and the like are not intended to describe corresponding components. Furthermore, the embodiments and features described in the embodiments of this application may be combined with one another unless there is a conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0032] Figure 1 1 shows a schematic diagram of an electronic device using a vehicle 1000 as an example. Figure 1 For ease of explanation, the following embodiments are described using a vehicle 1000 as an electronic device. However, it is readily understood that the electronic device provided herein is not limited to vehicles. The electronic device may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, electric tools, and the like.

[0033] The interior of the vehicle 1000 may be provided with a battery pack 1002, which may be provided at the bottom of the vehicle body 1001 (e.g., Figure 1 As shown) or head, or tail, or any other appropriate position. The battery pack 1002 can be used to power the vehicle 1000. For example, the battery pack 1002 can 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 Figure 2 and Figure 3 The secondary battery 100A described or Figure 4 and Figure 5 The secondary battery 100B described above and a case assembly for accommodating a plurality of secondary batteries.

[0034] It should be understood that the secondary battery in this application can be a variety of shapes, such as cylindrical, flat, rectangular, or other shapes, and the embodiments of this application are not limited to this. On the other hand, the secondary battery in this application can be a lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, etc., and the embodiments of this application are not limited to this.

[0035] Figure 2 FIG shows a perspective view of a secondary battery 100A according to an embodiment of the present application. Figure 2 In the illustrated embodiment, the secondary battery 100A is shown as a cylindrical battery as an example. Figure 3 FIG1 shows a cross-sectional view of a secondary battery 100A according to an embodiment of the present application. Figure 2 and Figure 3 As shown, the secondary battery 100A may include an electrode assembly 120, an electrolyte, a shell 200 and an end cap 202. The shell 200 may have an opening 205 at one end along the height direction (direction h), and the end cap 202 is provided at the opening 205 and blocks the accommodating cavity. The shell 200 and the end cap 202 are components that jointly accommodate the electrode assembly 120 and the electrolyte. The material of the shell 200 can be any one of a variety of available materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The shell 200 can be cylindrical and define an accommodating cavity, and the electrode assembly 120 is provided in the accommodating cavity. The diameter of the shell 200 can be determined according to the specific size 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 (46 mm in diameter, 80 mm in height), the secondary battery 100A may be a 4695 cylindrical battery (46 mm in diameter, 95 mm in height), or the secondary battery 100A may be a 46120 cylindrical battery (46 mm in diameter, 120 mm in height).

[0036] The housing 200 can be connected to the negative electrode of the electrode assembly 120. The secondary battery 100A can also have a terminal 208 at the end opposite the end cap 202. The terminal 208 can be connected to the positive electrode of the electrode assembly 120. It should be understood that the terminal 208 and the housing 200 are insulated to prevent battery short circuits.

[0037] In some embodiments, the electrode assembly 120 may include a first electrode sheet, a first separator, a second electrode sheet, and a second separator 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 is provided with a first electrode tab and a second electrode tab at both ends of the height direction h of the secondary battery 100, respectively. The 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 pole 208 so that the pole 208 is positively charged; the negative electrode tab faces the opening 205, and the housing 200 is electrically connected to the negative electrode tab so that it is negatively charged.

[0038] Figure 4 FIG. 1 shows a perspective view of a secondary battery 100B taking a square-cased battery as an example according to another embodiment of the present application. Figure 5 FIG1 shows a perspective view of an electrode assembly of a secondary battery 100B according to another embodiment of the present application, taking a square-shell battery as an example. Figure 4 and Figure 5 In the embodiment, the secondary battery 100B is a square shell battery. Figure 2 and Figure 3 As shown, the secondary battery 100B may include an electrode assembly 220, an electrolyte, a housing 300, and a cover assembly 302. The housing 300 may be a flat rectangular parallelepiped. One end of the housing 300 along the height direction h may have an opening (not shown), and the cover assembly 302 is provided at the opening. A first pole 311, a second pole 312, and an explosion-proof valve 313 are provided on the cover assembly 302. In some embodiments, the first pole 311 and the second pole 312 serve as a positive pole and a negative pole, respectively.

[0039] In some embodiments, the electrode assembly 220 may include a first electrode sheet, a first separator, a second electrode sheet, and a second separator 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. The 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 a flat rectangular parallelepiped electrode assembly 220. The electrode assembly 220 is provided with a first electrode tab 221 and a second electrode tab 222 at the same end in the height direction h of the secondary battery 100B. In some embodiments, the first electrode tab 221 and the second electrode tab 222 face the cover plate assembly 302, and the first electrode tab 221 and the second electrode tab 222 are electrically connected to the corresponding first electrode column 311 and the second electrode column 312, so that the first electrode column 311 and the second electrode column 312 are respectively positively or negatively charged.

[0040] The positive electrode sheet in a secondary battery (such as secondary batteries 100A and 100B) may include a positive electrode current collector and a positive electrode active material layer coated on both sides of the positive electrode current collector. The portion of the positive electrode current collector not coated with the positive electrode active material layer constitutes the positive electrode tab. The negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer coated on both sides of the negative electrode current collector. The portion of the negative electrode current collector not coated with the negative electrode active material layer constitutes the negative electrode tab. Taking a lithium-ion battery as an example, the material of the positive electrode current collector may be 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, or lithium manganese oxide. The material of the negative electrode current collector may be copper, and the negative electrode active material layer may include a negative electrode active material, which may be carbon or silicon, etc. In some embodiments, the material of the first separator and the second separator may be, for example, PP (polypropylene) or PE (polyethylene).

[0041] In addition, in order to prevent short circuit between the positive electrode sheet and the negative electrode sheet, an insulating material is usually coated near the edge of the positive active material layer of the positive electrode sheet or the negative active material layer of the negative electrode sheet to form an insulating layer.

[0042] The structure of the positive electrode sheet or negative electrode sheet (hereinafter referred to as the electrode sheet) of a secondary battery is as follows: Figure 6 Reference Figure 6 As shown, during the preparation process of the electrode sheet 10, a current collector 12 provided with a conductive layer 14 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 electrode sheet 10 is cut along the line Lc to obtain the electrode sheet 10. The resulting electrode sheet 10 may include the current collector 12, the conductive layer 14 and the insulating layer 16 spaced apart on the current collector 12, and the active material layer 18 disposed on the conductive layer 14. The active material layer 18 is completely located on the conductive layer 14, and the conductive layer 14 has a larger dimension in the first direction X than the active material layer 18.

[0043] During the aforementioned preparation process for the electrode sheet 10, the insulating layer 16 and the active material layer 18 are applied simultaneously. After the slurries for the insulating layer 16 and the active material layer 18 are applied to the current collector 12, the significant difference in interfacial tension can lead to mutual dissolution and bulging of the two slurries, potentially resulting in electrode sheet quality that does not meet 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 a tendency for the conductive layer 14 to be misaligned on both sides in the first direction X, resulting in misalignment of the active material layer 18 applied thereon. In addition, in the existing electrode 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. Since the size of the conductive layer 14 is larger than the active material layer 18, and the color difference between the conductive layer 14 and the active material layer 18 is usually small, the existing image monitoring equipment (such as a CCD camera) cannot effectively capture the edge of the active material layer 18, and thus cannot effectively monitor the size of the active material layer 18 and the gap G1 between the active material layer 18 and the insulating layer 16.

[0044] Figure 7 2 is a schematic cross-sectional view of a pole piece 20 according to an embodiment of the present application. Figure 8 yes Figure 7 The top view of the pole piece 20 is shown. Figure 7 and Figure 8 As shown, the electrode 20 may include a current collector 12, a conductive layer 14 and an insulating layer 16, and the insulating layer 16 is arranged on the same surface 12s of the current collector 12 with the conductive layer 14 spaced apart 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 can be to collect the new current generated by the active material in the battery to form a larger current for external output. Therefore, the current collector 12 generally adopts a metal material with as small internal resistance as possible, such as aluminum or copper. The current collector 12 is generally a metal foil. In some embodiments, when the electrode 20 is a positive electrode electrode, the current collector 12 may be an aluminum foil; when the electrode 20 is a negative electrode electrode, the current collector 12 may be a copper foil.

[0045] 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 extending beyond the conductive layer 14 may directly cover the current collector 12. A predetermined gap G2 is defined between the edge 18e of the active material layer 18 and the insulating layer 16.

[0046] In the above technical solution, the edge of the conductive layer 14 near the insulating layer 16 is covered by the active material layer 18, so that the edge of the active material layer 18 near the insulating layer 16 is directly coated on the current collector 12. Therefore, when the size of the active material layer 18 is monitored by a camera during coating (for example, using a CCD (charge coupled device)), there is no need to rely on the active material layer 18 and the conductive layer 14, which generally have a small color difference, to capture the edge of the active material layer 18. Therefore, the edge of the active material layer 18 can be effectively captured, and a predetermined gap G2 is set between the active material layer 18 and the insulating layer 16. This can effectively prevent the slurry of the active material layer 18 from dissolving with the insulating layer 16 and causing the edge to bulge, thereby improving the quality of the electrode.

[0047] In some embodiments, the insulating layer and the conductive layer are formed before the active material layer is formed. Specifically, during the process of forming the electrode sheet 20, the conductive layer 14 and the insulating layer 16 may be applied before the active material layer 18. 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; after forming the conductive layer 14 and the insulating layer 16, applying an active material layer slurry on the conductive layer 14 on the current collector 12, and drying the active material layer slurry to form the active material layer 18. In this process, since the insulating layer 16 is formed in advance, rather than applying the insulating layer 16 and the active material layer 18 simultaneously, when applying the active material layer 18, it is only necessary to monitor the edge flow of the active material layer 18 to control the preset gap G2 between the active material layer 18 and the insulating layer 16. This allows for effective control of the size of the active material layer 18 and the size of the gap G2, effectively avoiding the problem of mutual dissolution and bulging of the active material layer 18 slurry and the insulating layer 16 slurry.

[0048] The conductive layer 14 includes a conductive agent and a binder, the conductive agent includes 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 micro-powdered graphite, and the binder includes 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.

[0049] Insulating layer 16 may comprise an organic material. In some embodiments, insulating layer 16 comprises one selected from the group consisting of butyl acrylate, styrene, acrylic acid, hydroxyethyl acrylate, and styrene-butadiene rubber (SBR), or a mixture of two or more thereof. 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 some other embodiments in which insulating layer 16 comprises an organic material, insulating layer 16 comprises an insulating material and a binder, the binder comprising at least one of polyvinylidene fluoride, polyurethane, sodium polyacrylate, styrene-butadiene rubber, polyetherimide, carboxymethyl cellulose, and acrylate, and the insulating material comprising at least one of Al2O3, BaSO4, CaSiO3, γ-AlOOH, CaSiO4, and polytetrafluoroethylene.

[0050] 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, as such materials are more susceptible to shrinkage due to surface tension with the insulating layer. The design of the preset gap G2 described above in this application prevents the active material layer of the positive electrode sheet from dissolving with the insulating layer, thereby resolving this problem.

[0051] The active material layer 18 may specifically include a straight region 181 and a skived region 182 connected to one end of the straight region 181 along the first direction X. The skived region 182 is located at the end of the straight region 181 near the insulating layer 16. An edge 18e of the active material layer 18 near the insulating layer 16 is the edge of the skived region 182 away from the straight region 181. In other words, the edge 18e of the active material layer 18 near the insulating layer 16 is the edge of the skived region 182 formed during the coating process. This creates a gap between the skived region 182 and the insulating layer 16, more safely and effectively preventing problems such as miscibility and bulging of the active material layer 18 slurry and the insulating layer 16 slurry.

[0052] In the embodiment shown, edge 14e of conductive layer 14 adjacent to insulating layer 16 is covered by skived region 182. In other embodiments, edge 14e of conductive layer 14 may be covered by straight region 181, while skived region 182 may be located in the gap between conductive layer 14 and insulating layer 16.

[0053] In some embodiments, the color of the active material layer 18 is different from that of the current collector 12. It should be understood that the different colors in this application mean that the difference between the colors can be accurately identified by a CCD camera for edge capture. For example, the color of the active material layer 18 is usually black, and the color of the current collector 12 can usually be white. Since the color difference between the active material layer 18 and the current collector 12 thereunder is large, the edge 18e of the active material layer 18 can be accurately captured and monitored by a CCD camera during the coating of the active material layer 18, thereby improving the control accuracy of the coating process and avoiding misalignment of the active material layer 18.

[0054] In some embodiments, the identifiable color difference between the active material layer 18 and the current collector 12 is greater than the identifiable 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 generally black. Figure 6 As described, when the color difference between the active material layer 18 and the conductive layer 14 is small, it is not easy to grab the edge 18e of the active material layer 18 when applying the active material layer 18. The present application extends the edge 18e of the active material layer 18 to the current collector 12 where the color difference is larger, and the edge 18e of the active material layer 18 is directly applied to the current collector 12. Therefore, it is not necessary to rely on the active material layer 18 and the conductive layer 14, which generally have a small color difference, to grab the edge 18e of the active material layer 18. Therefore, the edge 18e can be effectively grabbed, thereby improving the control accuracy of the coating process of the active material layer 18. Since the control accuracy of the coating of the active material layer 18 is improved, the misalignment of the active material layer 18 can be avoided. In particular, even if the conductive layer 14 is misaligned, the active material layer 18 can be controlled not to be misaligned.

[0055] In some embodiments, the conductive layer 14 may be a carbon coating. In some embodiments, the thickness b μm of the conductive layer 14 may satisfy 0 < b μm ≤ 1.5 μm. If the thickness b μm of the conductive layer 14 is greater than 1.5 μm, the overall thickness of the active material layer 18 may be reduced, thereby potentially reducing the energy density of the battery.

[0056] In some embodiments, the distance L mm between the insulating layer 16 and the conductive layer 14 satisfies the following relationship: x / 2-0.5 mm < L mm < x / 2+0.5 mm, where x represents the width of the conductive layer 14 applied to the current collector 12 in the first direction X, in mm. If the distance L mm between the conductive layer 14 and the insulating layer 16 is too small, it will be difficult to apply the edge of the active material layer 18 between the conductive layer 14 and the insulating layer 16. If the distance L mm between the conductive layer 14 and the insulating layer 16 is too large, the exposed portion of the current collector 12 may be too large, resulting in a waste of current collector utilization.

[0057] In some embodiments, the gap G2 between the active material layer 18 and the insulating layer 16 in the first direction X ranges from 1 / 3 to 2 / 3 of the distance L mm (i.e., 1 / 3 L mm to 2 / 3 L mm). This gap G2 range ensures that the edge of the active material layer 18 can be coated on the current collector 12 within the process tolerance of the coating equipment, and that the gap G2 is maintained between the active material layer 18 and the insulating layer 16. In some embodiments, in the first direction X, the width of the active material coating 18 applied to the current collector 12 is d mm, and the width d mm can be equal to the total width of the active material coating 18 minus x. In some embodiments, 0 < d mm ≤ 5 mm.

[0058] In some embodiments, the thickness of the insulating layer 16 is tμm, the thickness of the active material layer 18 is Tμm, and the thickness tμm of the insulating layer 16 satisfies Tμm / tμm>2. If the thickness of the insulating layer 16 is too small, the insulating layer 16 may not be able to play the role of insulation protection. If the thickness of the insulating layer 16 is too large, the portion of the current collector 12 covered by the insulating layer 16 will not be easy to bend, which will be detrimental to the application of the electrode to, for example, a cylindrical battery. On the other hand, if the thickness of the active material layer 18 is too small, the energy density of the battery may be reduced. By reasonably setting the thickness of the insulating layer 16 and the active material layer 18, good results can be achieved in ensuring that the insulating layer 16 plays an insulating protection role, the current collector 12 is easy to bend, and the energy density of the battery is ensured.

[0059] In some embodiments, the current collector 12 may include a tab 125 that protrudes from the active material layer 18 in the first direction X. The tab 125 has a height H1 in the first direction X. The insulating layer 16 has a width W1 in the first direction X. The width W1 may be less than 1 / 3 of the height H1. Because a gap G2 can be effectively preset between the active material layer 18 and the insulating layer 16, a wide insulating layer 16 can be achieved, such that the width W1 of the insulating layer 16 can be increased to 1 / 3 of the height H1 of the tab 125.

[0060] In some embodiments, when the electrode 20 is a cylindrical battery electrode, the first direction X may correspond to Figure 2 In some embodiments, when the pole piece 20 is a pole piece of a square shell battery, the first direction X may correspond to Figure 4 The height direction h of the square shell battery.

[0061] The embodiment of the present application also provides a secondary battery (for example, Figure 2 、 Figure 3 The secondary battery 100A described and the reference Figure 4 、 Figure 5The secondary battery 100B described above may include: a housing having an opening for accommodating an electrode assembly, and an end cap for closing the opening. The electrode assembly includes the electrode sheet 20 in the aforementioned embodiment.

[0062] The embodiment of the present application further provides an electronic device, which may include the secondary battery in the aforementioned embodiment. The electronic device may be, for example, a reference Figure 1 Vehicle 1000 is described.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pole piece, characterized in that: include: current collector; conductive layer; an insulating layer, arranged on the same surface of the current collector and spaced apart from the conductive layer along a first direction; as well as an active material layer covering the conductive layer, Wherein, in the first direction, an edge of the active material layer facing the insulating layer exceeds the conductive layer, and a preset interval is provided between the edge of the active material layer and the insulating layer.

2. The pole piece according to claim 1, characterized in that: The distance L mm between the insulating layer and the conductive layer satisfies the following: x / 2-0.5 mm<L mm<x / 2+0.5 mm, wherein x represents the width of the conductive layer coated on the current collector in the first direction, in mm.

3. The pole piece according to claim 2, characterized in that: A size of the interval in the first direction ranges from 1 / 3 Lmm to 2 / 3 Lmm.

4. The pole piece according to claim 1, characterized in that: 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.

5. The pole piece according to claim 1, characterized in that: The current collector includes a tab protruding from the active material layer in the first direction, and the tab has a height in the first direction. The insulating layer has a width in the first direction, wherein the width is less than 1 / 3 of the height.

6. The pole piece according to claim 1, characterized in that: The active material layer has a different color from the current collector, or A recognizable color difference between the active material layer and the current collector is greater than a recognizable color difference between the active material layer and the conductive layer.

7. The pole piece according to claim 1, characterized in that: The active material layer includes a flat region and a thinned region connected to one end of the flat region along a first direction, wherein the thinned region is located at one end of the flat region close to the insulating layer.

8. The pole piece according to claim 1, characterized in that: The insulating layer and the conductive layer are formed before forming the active material layer.

9. A secondary battery, characterized in that: include: a housing having an opening for accommodating the electrode assembly; an end cap for closing the opening, Wherein, the electrode assembly includes the electrode piece according to any one of claims 1-8.

10. An electronic device, characterized in that: Comprising the secondary battery as claimed in claim 9.

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