Pole piece, electrochemical device, and electronic device

Abstract

The utility model discloses an electrode sheet, electrochemical device and electronic equipment, the electrode sheet is used for with diaphragm mutual laminating and winding and forms electrode assembly, and the electrode sheet includes current collector and active material layer, and the active material layer is located at the surface of current collector, and the active material layer forms a plurality of corner areas after winding, at least part corner area is equipped with at least one wire slot group, and the wire slot group includes first wire slot and a plurality of second wire slots, and one end of every second wire slot communicates with first wire slot, and the included angle is formed between second wire slot and first wire slot. The electrode sheet of the application aims at improving the infiltration speed of electrolyte at the corner in the electrochemical device and improving local lithium precipitation.

Description

Technical Field

[0001] This application relates to the field of electrochemical energy storage, and in particular to an electrode, an electrochemical device, and an electronic device. Background Technology

[0002] Lithium-ion batteries are widely used in energy storage, 3C products, new energy vehicles and other fields due to their advantages such as high energy density, long cycle life, high plateau voltage and good safety performance.

[0003] In lithium-ion battery manufacturing, to solve the problem of lithium plating at the electrode interface in high-silicon systems, it is necessary to improve the electrolyte wetting effect. Generally, laser etching is used to construct grooves to store electrolyte. However, the coverage of grooves formed by vertical etching at corners is not wide, and there are still wetting dead zones at corners, which reduces the electrolyte storage effect and weakens the effect of improving lithium plating. Utility Model Content

[0004] The main objective of this application is to provide an electrode that aims to improve the wetting speed and effect of the electrolyte at corners within an electrochemical device.

[0005] To achieve the above objectives, this application proposes an electrode sheet for being stacked and wound with a diaphragm to form an electrode assembly, the electrode sheet comprising:

[0006] current collector;

[0007] An active material layer is disposed on one surface of the current collector. After the electrode is wound, the active material layer forms multiple corner areas. At least a portion of the corner areas are provided with at least one line groove group. The line groove group includes a first line groove and multiple second line grooves. One end of each second line groove is connected to the first line groove, and an angle is formed between the second line groove and the first line groove.

[0008] In some embodiments, the number of the cable tray groups at at least a portion of the corner area is two.

[0009] In some embodiments, a plurality of second grooves within the groove group are located on opposite sides of the first groove.

[0010] In some embodiments, the two sets of grooves are symmetrical about the centerline of the corner region along the winding direction of the electrode sheet;

[0011] The length of the second groove on one side of the first groove is L1, and the length of the second groove on the other side of the first groove is L2. The L1 and L2 satisfy: L1>L2.

[0012] In some implementations, L1 satisfies: L1 > 3 mm; and / or,

[0013] The L2 satisfies: L2>1mm.

[0014] In some embodiments, the cable tray group further includes a third cable tray, which is arranged parallel to the first cable tray. Multiple second cable trays within the same cable tray group are located on the side of the first cable tray facing the third cable tray, and the other end of each second cable tray is connected to the third cable tray.

[0015] In some embodiments, at least one end of the second groove extends outward and is exposed in the first groove and / or the third groove.

[0016] In some embodiments, the ratio between the depth of the first groove and the thickness of the active material layer is A, wherein A satisfies: 0.3 ≤ A ≤ 0.7; and / or,

[0017] The width of the first groove is W1, wherein W1 satisfies: 40μm≤W1≤90μm; and / or,

[0018] The angle between the second groove and the first groove is α, where α satisfies: 30°≤α≤60°; and / or,

[0019] The ratio B between the depth of the second groove and the thickness of the active material layer satisfies: 0.3 ≤ B ≤ 0.7; and / or,

[0020] The width of the second groove is W2, and W2 satisfies: 40μm≤W2≤90μm.

[0021] In some embodiments, the active material layer has, in sequence along its width direction, a second scribe line region, a first scribe line region, and another second scribe line region;

[0022] The spacing between two adjacent second grooves within the first scribed area is D1, and the spacing between two adjacent second grooves within the second scribed area is D2. D1 and D2 satisfy the following condition: D1 <D2。

[0023] This application also proposes an electrochemical device, including an electrode assembly, the electrode assembly including a first electrode, a diaphragm and a second electrode arranged in a stacked and wound manner, the second electrode having the opposite polarity to the first electrode;

[0024] Wherein, at least one of the first electrode and the second electrode is an electrode as described above.

[0025] This application also proposes an electronic device including the electrochemical device described above.

[0026] The electrode in this application includes a current collector and an active material layer disposed on one surface of the current collector. The active material layer includes multiple spaced corner regions. During the electrode winding process to form an electrode assembly, the corner regions on the active material layer bend to form curved sections of the electrode assembly. At least a portion of the corner regions are provided with at least one set of grooves. Each set of grooves includes a first groove and multiple second grooves. The first grooves allow the electrolyte to flow along the width direction of the current collector. One end of each second groove is connected to a first groove, allowing the electrolyte to flow into the second groove through the first groove and flow along the extension direction of the second groove. An angle is formed between the second groove and the first groove. Compared with the traditional vertical straight structure, the second grooves at an angle to the first groove allow the electrode to have a longer extension length in the plane. The electrolyte can wet the coating along a longer oblique path, significantly increasing the penetration coverage area. At the same time, it provides a multi-level diffusion path, shortens the lateral diffusion distance of lithium ions, and improves the wetting speed and wetting effect of the electrolyte in the corner regions of the electrode. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the electrode structure in the first embodiment of this application;

[0028] Figure 2 for Figure 1 A magnified view of a section at point A in the middle;

[0029] Figure 3 This is a schematic diagram of the electrode structure according to the second embodiment of this application;

[0030] Figure 4 for Figure 3 A magnified view of a section at point B in the middle;

[0031] Figure 5 This is a schematic diagram of the electrode structure according to the third embodiment of this application;

[0032] Figure 6 This is a schematic diagram of the electrode structure according to the fourth embodiment of this application;

[0033] Figure 7 This is a schematic diagram of the electrode structure according to the fifth embodiment of this application;

[0034] Figure 8 This is a schematic diagram of the electrode structure of the sixth embodiment of this application.

[0035] Explanation of icon numbers:

[0036] 100, Electrode; 110, Current collector; 120, Active material layer; 121, Corner area; 1211, Groove group; 1211a, First groove; 1211b, Second groove; 1211c, Third groove; α, Angle; 122, First scribe line area; 123, Second scribe line area; 1212, Center line. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. The embodiments of this application may omit unnecessary detailed descriptions. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0038] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0039] As used in this article, the terms “roughly,” “generally,” “substantially,” and “about” are used to describe and explain minor variations.

[0040] When used in conjunction with an event or situation, the term may refer to examples in which the event or situation occurred precisely and examples in which the event or situation occurred very approximately. For example, when used in conjunction with numerical values, the term may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the difference between two numerical values ​​is less than or equal to ±10% of the average of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%), then the two numerical values ​​can be considered "substantially" the same.

[0041] Furthermore, for ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0042] Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format in this document. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0043] In the detailed description and claims, a list of items connected by the terms "one of," "among," "a kind of," or other similar terms may mean any of the listed items. For example, if items A and B are listed, then the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0044] In the detailed description and claims, the list of items connected by the term "at least one of" can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.

[0045] In the following description, all figures disclosed in this application are approximate values, regardless of whether the terms "about" or "approximately" are used in conjunction. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a range of values ​​with a lower limit (RL) and an upper limit (RU) is disclosed, any values ​​falling within that range are specifically disclosed. Specifically, the following values ​​within this range are specifically disclosed: R = RL + k * (RU - RL), where k is a variable with a 1% increment from 1% to 100%, that is, k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any range of values ​​defined by the two R values ​​as defined above are also specifically disclosed.

[0046] Throughout this specification, references to “implementation,” “partial implementation,” “one implementation,” “another implementation,” “specific method,” or “partial method” mean that at least one implementation or embodiment in this application includes the specific features, structures, materials, or characteristics described in that implementation or embodiment.

[0047] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form a range not explicitly stated.

[0048] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

[0049] Lithium-ion batteries are widely used in energy storage, 3C products, new energy vehicles and other fields due to their advantages such as high energy density, long cycle life, high plateau voltage and good safety performance.

[0050] In lithium-ion battery manufacturing, to solve the problem of lithium plating at the electrode interface in high-silicon systems, it is necessary to improve the electrolyte wetting effect. Generally, laser etching is used to construct grooves to store electrolyte. However, the coverage of grooves formed by vertical etching at corners is not wide, and there are still wetting dead zones at corners, which reduces the electrolyte storage effect and weakens the effect of improving lithium plating.

[0051] To achieve the above objectives, this application proposes an electrode 100 for being stacked and wound with a diaphragm to form an electrode assembly, as shown in the reference. Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of the electrode 100 in the first embodiment of this application. Figure 2 for Figure 1 The enlarged view at point A shows that the electrode 100 includes a current collector 110 and an active material layer 120. The active material layer 120 is disposed on one surface of the current collector 110. After the electrode 100 is wound, the active material layer 120 forms multiple corner regions 121. At least some of the corner regions 121 are provided with at least one line groove group 1211. The line groove group 1211 includes a first line groove 1211a and multiple second line grooves 1211b. One end of each second line groove 1211b is connected to the first line groove 1211a. An angle α is formed between the second line groove 1211b and the first line groove 1211a.

[0052] In this embodiment, the current collector 110 can be a metal foil or a composite current collector 110. Depending on the polarity, the metal foil can be an aluminum foil or a copper foil. The composite current collector 110 can include a metal foil substrate and a conductive layer disposed on at least one side of the metal foil substrate. Depending on the polarity, the metal foil substrate can be an aluminum foil substrate or a copper foil substrate. The conductive layer can be carbon, carbon black, graphite, expanded graphite, or other carbon materials. The active material layer can include an active material, a binder, and a conductive agent. The active material can be lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, NMC, NCA, or other materials that can be used as active materials. The binder can be polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), or other materials that can be used as battery binders. The conductive agent can be carbon, carbon black, graphite, expanded graphite, graphene, or other materials that can be used as battery conductive agents. During the process of winding the electrode sheet 100 to form an electrode assembly, the corner area 121 on the active material layer 120 bends to form the bent section of the electrode assembly. The bend of the corner area 121 makes it easier for dead zones of electrolyte to appear, and the wetting rate and effect are not ideal.

[0053] At least some corner areas 121 are provided with at least one line groove group 1211. Furthermore, to improve the storage and wetting effect of the electrolyte, each corner area 121 is provided with at least one line groove group 1211. The line groove group 1211 includes at least a first line groove 1211a and a second line groove 1211b. The first line groove 1211a is a main flow guiding structure arranged along or inclined along the width direction of the current collector 110, serving to store the electrolyte and conduct ion flow along the width direction of the current collector 110. The first line groove 1211a can be formed by laser drilling, specifically it can be a straight groove structure, or a structure of multiple circular holes arranged in a straight line and connected, or a structure of multiple polygonal holes arranged in a straight line and connected, etc., without further limitation. The length of the first line groove 1211a can be the same as the width of the current collector 110, or there can be gaps between the two ends of the first line groove 1211a and the two sides of the current collector 110.

[0054] The second groove 1211b is a branching flow-guiding structure forming an angle α with the first groove 1211a. It serves to divert the electrolyte and distribute the ion flow to smaller regional units, covering the middle region of the two first grooves 1211a with lithium-ion transport channels. The other ends of adjacent second grooves 1211b maintain a certain distance to ensure the center of the corner area 121 is not exposed, reducing the risk of cracks due to uneven stress at the center of the corner area 121 during winding. The second groove 1211b can be formed by laser drilling. Specifically, it can be a straight groove structure, a structure of multiple interconnected circular holes arranged in a straight line, or a structure of multiple interconnected polygonal holes arranged in a straight line, etc., without further limitation.

[0055] One end of each second groove 1211b is connected to the first groove 1211a, and the other end of the second groove 1211b extends outwards. The direction of extension of the second groove 1211b can be either from top to bottom, gradually moving away from the first groove 1211a, or from top to bottom, gradually moving closer to the first groove 1211a. Multiple second grooves 1211b connected to both sides of the same first groove 1211a can be arranged symmetrically about the first groove 1211a, or they can be staggered on opposite sides of the first groove 1211a. Multiple second grooves 1211b connected to the same side of the same first groove 1211a are evenly spaced. Multiple second grooves 1211b connected to different first grooves 1211a can be connected to the same position of the corresponding first grooves 1211a. Each first groove 1211a and the multiple second grooves 1211b above it form a flow-guiding structure of the same shape, making the distribution and wetting of the electrolyte more uniform and improving its wetting and liquid retention effect. The included angle α between the second groove 1211b and the first groove 1211a can be an acute angle, a right angle, or an obtuse angle, and is not further limited here.

[0056] The electrode 100 in this application includes a current collector 110 and an active material layer 120 disposed on one surface of the current collector 110. The active material layer 120 includes a plurality of spaced corner regions 121. During the winding process of the electrode 100 to form an electrode assembly, the corner regions 121 on the active material layer 120 are bent to form a bent section of the electrode assembly. At least a portion of the corner regions 121 are provided with at least one line groove group 1211. Each line groove group 1211 includes a first line groove 1211a and a plurality of second line grooves 1211b. The first line groove 1211a allows the electrolyte to flow along the width direction of the current collector 110. One end of each second line groove 1211b is connected to a first line groove 1211a. The grooves 1211a are connected, allowing the electrolyte to flow into the second groove 1211b through the first groove 1211a and flow along the extension direction of the second groove 1211b. The second groove 1211b and the first groove 1211a form an angle α. Compared with the traditional vertical straight structure, the second groove 1211b, which forms an angle α with the first groove 1211a, allows the electrode 100 to have a longer extension length in the plane. The electrolyte can wet the coating along a longer oblique path, significantly increasing the coverage area of ​​the penetration. At the same time, it provides a multi-level diffusion path, shortens the lateral diffusion distance of lithium ions, and improves the wetting speed and wetting effect of the electrolyte in the corner area 121 of the electrode 100.

[0057] According to some embodiments of this application, at least a portion of the corner area 121 has two wire trough groups 1211.

[0058] In this embodiment, at least one corner area 121 contains two groove groups 1211. Each groove group 1211 includes a first groove 1211a and multiple second grooves 1211b. Each groove group 1211 forms a dendritic or herringbone-shaped scribe structure, which further improves the storage and wetting effect of the electrolyte in the corner area 121.

[0059] Based on some embodiments of this application, refer again Figure 1 and Figure 2 The multiple second grooves 1211b within the groove group 1211 are located on opposite sides of the first groove 1211a.

[0060] In this embodiment, second grooves 1211b are connected to both sides of the first groove 1211a within the same groove group 1211, thereby increasing the coverage area of ​​the multiple second grooves 1211b and thus improving the wetting speed and effect of the electrolyte. The multiple second grooves 1211b connected to the opposite sides of the same first groove 1211a can be arranged symmetrically about the first groove 1211a or staggered. The orientation of the multiple second grooves 1211b on both sides can be the same or opposite, and no further limitation is made here.

[0061] According to some embodiments of this application, refer to Figure 2 Along the winding direction of the electrode 100, the two groove groups 1211 are symmetrical about the center line 1212 of the corner area 121;

[0062] The length of the second groove 1211b on one side of the first groove 1211a is L1, and the length of the second groove 1211b on the other side of the first groove 1211a is L2. L1 and L2 satisfy: L1>L2.

[0063] In this embodiment, along the winding direction of the electrode 100, two groove groups 1211 are symmetrically arranged about the center line 1212 of the corner area 121, with a gap between them. This reduces the risk of cracks caused by uneven stress at the center line 1212 of the corner area 121 during winding. The lengths of the second grooves 1211b on both sides of the first groove 1211a are different, with the length of the second groove 1211b on one side being greater than that on the other side. In a preferred embodiment, the length of the second groove 1211b on the side of the first groove 1211a facing the center line 1212 of the corner area 121 is greater than the length of the second groove 1211b on the other side. That is, the coverage area of ​​the multiple second grooves 1211b near the center line 1212 of the corner area 121 is larger. Since the bending degree near the center line 1212 of the corner area 121 is greater, the required length of the second groove 1211b is also longer, so as to accommodate more electrolyte, extend the diffusion path of electrolyte, and improve the wetting speed and wetting effect of electrolyte in the corner area 121 of the electrode 100.

[0064] According to some embodiments of this application, L1 satisfies: L1 > 3mm; and / or,

[0065] L2 satisfies: L2>1mm.

[0066] For example, the length of the second groove 1211b connected to the first groove 1211a on the side facing the centerline 1212 of the corner area is greater than 3 mm, such as 4 mm, 5 mm, 6 mm, or within any two of the above values, to extend the diffusion path of the electrolyte between the two first grooves 1211a, thereby improving the wetting speed and effect of the electrolyte in the corner area 121 of the electrode 100. The length of the second groove 1211b connected to the first groove 1211a away from the centerline 1212 of the corner area is greater than 1 mm, such as 2 mm, 3 mm, 4 mm, or within any two of the above values, to extend the diffusion path of the electrolyte outside the two first grooves 1211a, so that the ion lateral diffusion channel extends to the main interface of the electrode 100, reducing the purple spot lithium deposition at the main interface of the electrode 100.

[0067] According to some embodiments of this application, refer to Figure 5 , Figure 5This is a schematic diagram of the structure of the electrode 100 in the third embodiment of this application. The wire groove group 1211 also includes a third wire groove 1211c. The third wire groove 1211c is arranged parallel to the first wire groove 1211a. Multiple second wire grooves 1211b in the same wire groove group 1211 are located on the side of the first wire groove 1211a facing the third wire groove 1211c. The other end of each second wire groove 1211b is connected to the third wire groove 1211c.

[0068] In this embodiment, the groove group 1211 further includes a third groove 1211c arranged parallel to the first groove 1211a. The two ends of multiple second grooves 1211b within the same groove group 1211 are respectively connected to the first groove 1211a and the third groove 1211c. The third groove 1211c is a main flow guiding structure arranged along the width direction of the current collector 110 or inclined thereon, serving to store electrolyte and conduct ion flow along the width direction of the current collector 110. The third groove 1211c can be formed by laser drilling. Specifically, it can be a straight groove structure, or multiple circular holes arranged in a straight line and connected, or multiple polygonal holes arranged in a straight line and connected, etc., without further limitation. The length of the third groove 1211c can be the same as the width of the current collector 110, or there can be gaps between the two ends of the third groove 1211c and the two sides of the current collector 110. However, when the third groove 1211c is inclined, its length can be slightly greater than the width of the current collector 110. The first groove 1211a and the third groove 1211c are spaced apart in a corner area 121. The first groove 1211a and the third groove 1211c can store more electrolyte and have the effect of diverting electrolyte, so that the stored electrolyte is also distributed along the corner area 121, thereby improving the wetting speed and wetting effect of the electrolyte in the corner area 121.

[0069] Multiple inclined second grooves 1211b are constructed between the first groove 1211a and the third groove 1211c, covering the centerline 1212 of the corner region 121. Each node unit of the inclined second groove 1211b has lateral and longitudinal vector diffusion, which enables ions to penetrate rapidly along the direction of the second groove 1211b, thereby improving the penetration effect of the electrolyte.

[0070] According to some embodiments of this application, refer to Figure 7 , Figure 7 This is a schematic diagram of the structure of the electrode 100 in the fifth embodiment of this application. At least one end of the second groove 1211b extends outward and is exposed in the first groove 1211a and / or the third groove 1211c.

[0071] In this embodiment, at least one end of the second groove 1211b extends outward so that the second groove 1211b can cover the corner region 121 and part of the main interface side, thereby constructing an ion lateral diffusion channel in the corner region 121 and the surrounding area to expand the lithium ion transport range to the main interface region and reduce the problem of purple spot lithium deposition in the weak interface areas such as the main interface.

[0072] According to some embodiments of this application, the ratio between the depth of the first groove 1211a and the thickness of the active material layer 120 is A, where A satisfies: 0.3 ≤ A ≤ 0.7; and / or,

[0073] The width of the first groove 1211a is W1, where W1 satisfies: 40μm≤W1≤90μm; and / or,

[0074] Reference Figure 2 and Figure 4 The angle α between the second groove 1211b and the first groove 1211a is α, which satisfies: 30°≤α≤60°; and / or,

[0075] The ratio B between the depth of the second groove 1211b and the thickness of the active material layer 120 satisfies: 0.3 ≤ B ≤ 0.7; and / or,

[0076] The width of the second groove 1211b is W2, which satisfies: 40μm≤W2≤90μm.

[0077] For example, the ratio A between the depth of the first groove 1211a and the thickness of the active material layer 120 is 0.3, 0.4, 0.5, 0.6, or 0.7, or falls within the range of any two of the above values. When the ratio A between the depth of the first groove 1211a and the thickness of the active material layer 120 is less than 0.3, the volume of the first groove 1211a is small, and the amount of electrolyte that can be contained in the first groove 1211a is also small, which affects the wetting rate and wetting effect of the electrolyte in the battery. When the ratio between the depth of the first groove 1211a and the thickness of the active material layer 120 is greater than 0.7, the volume of the first groove 1211a is large, which leads to a lower content of active material in the active material layer 120, affecting the performance of the battery.

[0078] For example, the width W1 of the first groove 1211a is 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm, or falls within any two of the above values. When the width of the first groove 1211a is less than 40 μm, the volume of the first groove 1211a is small, and the amount of electrolyte that can be contained in the first groove 1211a is also small, which affects the wetting rate and wetting effect of the electrolyte in the battery. When the width of the first groove 1211a is greater than 90 μm, the volume of the first groove 1211a is large, which leads to a low content of active material in the active material layer 120, thus affecting the performance of the battery.

[0079] For example, the included angle α between the second groove 1211b and the first groove 1211a is 30°, 45°, or 60°, or falls within the range of any two of these values. When the included angle α is less than 30°, the streamline radius of curvature at the connection between the first groove 1211a and the second groove 1211b is too small, resulting in boundary layer separation and the formation of a low-pressure dead zone. This, in turn, hinders the flow of the electrolyte, reduces the wetting rate of the electrolyte, and affects the wetting effect. When the included angle α is greater than 60°, with the horizontal distance between the distal end of the second groove 1211b and the first groove 1211a remaining constant, the larger the included angle α, the shorter the length of the second groove 1211b, reducing the wetting area covered by the second groove 1211b and affecting the wetting effect of the electrolyte.

[0080] For example, the ratio B between the depth of the second groove 1211b and the thickness of the active material layer 120 is 0.3, 0.4, 0.5, 0.6, or 0.7, or falls within any two of the aforementioned values. When the ratio B between the depth of the second groove 1211b and the thickness of the active material layer 120 is less than 0.3, the volume of the second groove 1211b is small, and the amount of electrolyte that can be contained within the second groove 1211b is also small, thereby affecting the wetting rate and wetting effect of the electrolyte within the battery. When the ratio between the depth of the second groove 1211b and the thickness of the active material layer 120 is greater than 0.7, the volume of the second groove 1211b is large, which leads to a lower content of active material in the active material layer 120, affecting the performance of the battery.

[0081] For example, the width W2 of the second groove 1211b is 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm, or falls within any two of the above values. When the width of the second groove 1211b is less than 40 μm, the volume of the second groove 1211b is small, and the amount of electrolyte that can be contained in the second groove 1211b is also small, which affects the wetting rate and wetting effect of the electrolyte in the battery. When the width of the second groove 1211b is greater than 90 μm, the volume of the second groove 1211b is large, which leads to a low content of active material in the active material layer 120, thus affecting the performance of the battery.

[0082] According to some embodiments of this application, refer to Figure 3 , Figure 4 , Figure 6 and Figure 8 , Figure 3 This is a schematic diagram of the structure of the electrode 100 in the second embodiment of this application. Figure 4 for Figure 3 A magnified view of a section at point B. Figure 6 This is a schematic diagram of the structure of the electrode 100 in the fourth embodiment of this application. Figure 8 This is a schematic diagram of the structure of the electrode 100 in the sixth embodiment of this application. The active material layer 120 has a second scribing area 123, a first scribing area 122 and another second scribing area 123 in sequence along its width direction.

[0083] The spacing between two adjacent second grooves 1211b within the first scribed area 122 is D1, and the spacing between two adjacent second grooves 1211b within the second scribed area 123 is D2. D1 and D2 satisfy: D1 <D2。

[0084] In this embodiment, the current collector 110 has a first etched area 122 close to the central axis of the current collector 110 along its width direction and a second etched area 123 located on both sides of the first etched area 122 and close to the edge of the current collector 110. The distance between two adjacent second grooves 1211b in the second etched area 123 is greater than the distance between two adjacent second grooves 1211b in the first etched area 122. By using multiple second grooves 1211b with smaller spacing in the first etched area 122, the coverage area of ​​the ion channel is increased, and the diffusion path of the electrolyte is extended, so as to solve the problem of severe lithium plating in the center of the corner area 121. In the central area, the CW (Coating weight) is reduced and the CB (Cell Balance) is increased, the weight of the cathode active material is reduced, the ratio of the negative electrode active material to the positive electrode is increased, the electrolyte retention effect is improved, and thus the lithium plating is improved. The lithium plating in the areas on both sides of the electrode 100 is relatively small, and the etched multiple second grooves 1211b can be sparser to reduce the loss of active material. Understandably, the density of the spacing between two adjacent second grooves 1211b can be selected based on the severity of lithium plating.

[0085] This application also provides an electrochemical device, including any device in which an electrochemical reaction occurs to interconvert chemical energy and electrical energy, including, but not limited to, all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0086] In some embodiments, the electrochemical device includes an electrode assembly comprising a first electrode, a diaphragm, and a second electrode arranged in a stacked and wound manner, the second electrode having the opposite polarity to the first electrode;

[0087] In this embodiment, at least one of the first electrode and the second electrode is an electrode 100 as described above.

[0088] This application also provides an electronic device that includes the electrochemical device described above.

[0089] The electronic device described in this application is not particularly limited and can be applied to any electronic device known in the prior art.

[0090] According to some embodiments of this application, electronic devices include, but are not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, robot dogs, industrial robots, and android robots.

[0091] When the term "embodiment" is mentioned in the specification, it means that there is at least one embodiment in this application that includes the specific feature, structure, material, or characteristic. Therefore, expressions such as "in some embodiments," "in certain embodiments," and "exemplary" used throughout the document do not necessarily refer to the same embodiment. Furthermore, the specific feature, structure, material, or characteristic may be combined in any suitable manner in one or more embodiments.

[0092] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. An electrode sheet for being stacked and wound with a diaphragm to form an electrode assembly, characterized in that, The electrode includes: current collector; An active material layer is disposed on one surface of the current collector. After the electrode is wound, the active material layer forms multiple corner areas. At least a portion of the corner areas are provided with at least one line groove group. The line groove group includes a first line groove and multiple second line grooves. One end of each second line groove is connected to the first line groove, and an angle is formed between the second line groove and the first line groove.

2. The electrode sheet according to claim 1, characterized in that, At least a portion of the corner area has two sets of cable trays.

3. The electrode sheet according to claim 2, characterized in that, The plurality of second grooves in the groove group are located on opposite sides of the first groove.

4. The electrode sheet according to claim 3, characterized in that, Along the winding direction of the electrode sheet, the two sets of grooves are symmetrical about the centerline of the corner area; The length of the second groove on one side of the first groove is L1, and the length of the second groove on the other side of the first groove is L2. The L1 and L2 satisfy: L1>L2.

5. The electrode sheet according to claim 4, characterized in that, The L1 satisfies: L1>3mm; and / or, The L2 satisfies: L2>1mm.

6. The electrode sheet according to claim 1, characterized in that, The cable tray group also includes a third cable tray, which is arranged parallel to the first cable tray. Multiple second cable trays in the same cable tray group are located on the side of the first cable tray facing the third cable tray, and the other end of each second cable tray is connected to the third cable tray.

7. The electrode sheet according to claim 6, characterized in that, At least one end of the second groove extends outward and is exposed in the first groove and / or the third groove.

8. The electrode sheet according to any one of claims 1 to 7, characterized in that, The ratio A between the depth of the first groove and the thickness of the active material layer satisfies: 0.3 ≤ A ≤ 0.7; and / or, The width of the first groove is W1, wherein W1 satisfies: 40μm≤W1≤90μm; and / or, The angle between the second groove and the first groove is α, where α satisfies: 30°≤α≤60°; and / or, The ratio B between the depth of the second groove and the thickness of the active material layer satisfies: 0.3 ≤ B ≤ 0.7; and / or, The width of the second groove is W2, and W2 satisfies: 40μm≤W2≤90μm.

9. The electrode sheet according to any one of claims 1 to 7, characterized in that, The active material layer has a second scribed area, a first scribed area and another second scribed area in sequence along its width direction; The spacing between two adjacent second grooves within the first scribed area is D1, and the spacing between two adjacent second grooves within the second scribed area is D2. D1 and D2 satisfy the following condition: D1 <D2。 10. An electrochemical device, characterized in that, The device includes an electrode assembly comprising a first electrode, a diaphragm, and a second electrode arranged in a stacked and wound manner, wherein the polarity of the second electrode is opposite to that of the first electrode. Wherein, at least one of the first electrode and the second electrode is an electrode as described in any one of claims 1 to 9.

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

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