Pole piece, electrochemical device, and electronic device

Abstract

The application discloses a pole piece, an electrochemical device and an electronic device. The pole piece comprises a current collector and an active material layer. The active material layer is arranged on one surface of the current collector. The active material layer is provided with a first groove, a second groove and a third groove. The first groove extends along the length direction of the current collector. One end of the second groove is communicated with the first groove. The other end of the second groove is extended and arranged. A first included angle is formed between the extension direction of the second groove and the extension direction of the first groove. One end of the third groove is communicated with the second groove. The other end of the third groove is extended and arranged. A second included angle is formed between the extension direction of the third groove and the extension direction of the second groove. The pole piece aims to improve the transverse infiltration speed of the electrolyte in the battery and improve 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] In current lithium-ion battery electrode manufacturing, laser drilling is commonly used to create longitudinal straight trenches to address the electrolyte wetting problem. However, longitudinal straight trenches cannot directly provide an effective continuous lateral penetration path. The lateral diffusion of the electrolyte within these trenches relies solely on the inherent microporous structure of the coating material itself. This results in a lateral wetting rate that is much lower than the longitudinal wetting rate, making it difficult for the electrolyte to distribute evenly. Consequently, ion transport paths are obstructed, local concentration polarization intensifies, and localized lithium plating occurs. Utility Model Content

[0003] The main objective of this application is to propose an electrode that aims to improve the lateral wetting rate of the electrolyte inside the battery and improve local lithium plating.

[0004] To achieve the above objectives, this application proposes an electrode sheet comprising: current collector; An active material layer is disposed on one surface of the current collector. The active material layer has a first groove, a second groove, and a third groove. The first groove extends along the length direction of the current collector. One end of the second groove is connected to the first groove, and the other end of the second groove extends outward, forming a first angle between the extension direction of the second groove and the extension direction of the first groove. One end of the third groove is connected to the second groove, and the other end of the third groove extends outward, forming a second angle between the extension direction of the third groove and the extension direction of the second groove.

[0005] In some embodiments, there are multiple second grooves, which are disposed on opposite sides of the first groove, and the second grooves on either side of the first groove are spaced apart along the extending direction of the first groove.

[0006] In some embodiments, the number of the third grooves is multiple; At least one of the third grooves is provided on each of the opposite sides of each of the second grooves.

[0007] In some embodiments, one end of the electrode is the starting end of the winding located on the inner ring of the battery cell after winding, and the other end is the ending end of the winding located on the outer ring of the battery cell after winding. In the direction from the starting end of the winding to the ending end of the winding, the spacing between adjacent second grooves gradually increases.

[0008] In some embodiments, the width of the plurality of second grooves gradually decreases in the direction from the winding start end to the winding end end.

[0009] In some embodiments, the depth of the plurality of second grooves gradually decreases in the direction from the winding start end to the winding end end.

[0010] In some embodiments, the width of the second groove is ratio A to the width of the first groove, wherein A satisfies: 0.3 ≤ A ≤ 0.5; and / or, The width of the third groove is B in ratio to the width of the second groove, wherein B satisfies: 0.3≤B≤0.5.

[0011] In some embodiments, the first included angle is α, where α satisfies: 30°≤α≤90°; and / or, The second included angle is β, and β satisfies: 30°≤β≤90°.

[0012] 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; Wherein, at least one of the first electrode and the second electrode is an electrode as described above.

[0013] This application also proposes an electronic device including the electrochemical device described above.

[0014] 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 has a first groove, a second groove, and a third groove. The first groove extends along the length of the current collector. One end of the second groove is connected to the first groove, and the other end of the second groove extends and forms a first angle with the extension direction of the first groove. One end of the third groove is connected to the second groove, and the other end of the third groove extends and forms a second angle with the extension direction of the second groove. During electrolyte injection, the electrolyte preferentially and rapidly fills the third and second grooves, and then weaves outwards from the third and second grooves, subsequently flowing into the first groove. The electrolyte rapidly weaves along the length of the current collector via the first groove. The guiding structure formed by the first, second, and third grooves can not only improve the wetting speed of the electrolyte in the lateral direction (the length direction of the current collector), but also provide a longer wetting path through the second and third grooves, increasing the wetting rate of the electrolyte in the length direction, making the electrolyte distribution more uniform, and thus improving the local lithium plating problem. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the electrode sheet in one embodiment of this application; Figure 2 This is a schematic diagram of the electrode structure in another embodiment of this application.

[0016] Explanation of icon numbers: 100, Electrode; 110, Current collector; 120, Active material layer; 121, First groove; 122, Second groove; 123, Third groove; α, First included angle; β, Second included angle. Detailed Implementation

[0017] 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.

[0018] 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.

[0019] As used in this article, the terms “roughly,” “generally,” “substantially,” and “about” are used to describe and explain minor variations.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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 ranging from 1% to 100% with a 1% increment, i.e., 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] In current lithium-ion battery electrode manufacturing, laser drilling is commonly used to create longitudinal straight trenches to address the electrolyte wetting problem. However, longitudinal straight trenches cannot directly provide an effective continuous lateral penetration path. The lateral diffusion of the electrolyte within these trenches relies solely on the inherent microporous structure of the coating material itself. This results in a lateral wetting rate that is much lower than the longitudinal wetting rate, making it difficult for the electrolyte to distribute evenly. Consequently, ion transport paths are obstructed, local concentration polarization intensifies, and localized lithium plating occurs.

[0030] To achieve the above objectives, this application proposes an electrode 100, with reference to... Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of the electrode 100 in one embodiment of this application. Figure 2The diagram below shows the structure of the electrode 100 in another embodiment of this application. In some embodiments, 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. The active material layer 120 has a first groove 121, a second groove 122 and a third groove 123. The first groove 121 extends along the length direction of the current collector 110. One end of the second groove 122 is connected to the first groove 121, and the other end of the second groove 122 extends outward. A first angle α is formed between the extension direction of the second groove 122 and the extension direction of the first groove 121. One end of the third groove 123 is connected to the second groove 122, and the other end of the third groove 123 extends outward. A second angle β is formed between the extension direction of the third groove 123 and the extension direction of the second groove 122.

[0031] In this embodiment, the electrode 100 includes a current collector 110 and an active material layer 120 disposed on at least one side of the current collector 110. The current collector 110 may be a metal foil or a composite current collector 110. In some embodiments, the metal foil may be a copper foil or an aluminum foil. The composite current collector 110 may include a metal foil substrate and a conductive layer disposed on at least one side of the metal foil substrate.

[0032] According to some embodiments of this application, the active material layer 120 has a first groove 121, a second groove 122, and a third groove 123. The first groove 121, the second groove 122, and the third groove 123 are all formed by laser drilling. The first groove 121, the second groove 122, and the third groove 123 can be linear or formed by arranging multiple circular holes or holes of other shapes; no further limitation is made here. The first groove 121 is a main guiding structure extending along the length direction of the current collector 110, allowing the electrolyte to extend along the length direction of the current collector 110 and wet the active material layer 120, improving the efficiency of lateral electrolyte wetting and mitigating the problem of localized lithium plating.

[0033] The second groove 122 is a primary branch flow guide structure that is connected and communicates with the first groove 121 at an angle. One end of the second groove 122 is connected to the first groove 121, and the other end of the second groove 122 can extend toward the starting end of the winding of the current collector 110, or it can extend toward the beginning and end of the winding of the current collector 110. The length of the second groove 122 can be from the first groove 121 to the edge of the current collector 110, or it can have a gap between it and the edge of the current collector 110. The specific length of the second groove 122 can be selected according to actual needs.

[0034] The third groove 123 is a secondary branch flow guiding structure that is connected and communicates with the second groove 122 at an angle. One end of the third groove 123 is connected to the second groove 122, and the other end of the third groove 123 can extend towards the first groove 121 or away from the first groove 121, without further limitation. The length of the third groove 123 should be such that it does not interfere with each other, so as to maximize the wetting area of ​​the electrolyte. The specific length value should be selected according to actual needs.

[0035] The electrolyte can be wetted along the extension direction of the second groove 122 and the third groove 123 which are angled. The angled branch design provides a longer wetting path in the plane of the electrode 100. The electrolyte can more fully wet the active material layer 120 along this path, significantly expanding the penetration coverage area, especially improving the wetting effect in the center region of the electrode.

[0036] 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 has a first groove 121, a second groove 122, and a third groove 123. The first groove 121 extends along the length direction of the current collector 110. One end of the second groove 122 communicates with the first groove 121, and the other end of the second groove 122 extends and forms a first angle α with the extension direction of the first groove 121. One end of the third groove 123 communicates with the second groove 122, and the other end of the third groove 123 extends and forms a second angle β with the extension direction of the second groove 122. During electrolyte injection, the electrolyte preferentially and rapidly fills the third groove 123 and the second groove 122, and then permeates outward from the third groove 123 and the second groove 122, subsequently flowing into the first groove 121. The electrolyte rapidly permeates along the length direction of the current collector 110 via the first groove 121. The flow-guiding structure formed by the first groove 121, the second groove 122, and the third groove 123 can not only increase the wetting speed of the electrolyte in the lateral direction (the length direction of the current collector 110), but also provide a longer wetting path through the second groove 122 and the third groove 123, thereby increasing the wetting rate of the electrolyte in the length direction, making the distribution of the electrolyte more uniform, and thus improving the local lithium plating problem.

[0037] According to some embodiments of this application, refer to Figure 1 There are multiple second grooves 122, which are located on opposite sides of the first groove 121. The second grooves 122 on either side of the first groove 121 are distributed at intervals along the extension direction of the first groove 121.

[0038] In this embodiment, multiple second grooves 122 are provided, with the second grooves 122 located on the same side of the first groove 121 spaced apart to increase the coverage area of ​​the second grooves 122. This allows the electrolyte to flow into the first groove 121 through the multiple second grooves 122, and the electrolyte can also be wetted to both sides through the multiple second grooves 122, further improving the electrolyte wetting rate, shortening the static wetting time after battery injection, improving production efficiency, and mitigating the problem of local lithium plating. It is understood that, in a preferred embodiment, the first groove 121 is located at the central axis of the current collector 110 and extends along the length of the current collector 110. The multiple second grooves 122 are symmetrically arranged on opposite sides of the first groove 121, and the multiple second grooves 122 located on the same side of the first groove 121 are evenly distributed at intervals along the extension direction of the first groove 121, so that the electrolyte wetting is more uniform, thereby improving the wetting speed.

[0039] According to some embodiments of this application, refer to Figure 1 The number of third grooves 123 is multiple; Each second groove 122 has at least one third groove 123 on each of its opposite sides.

[0040] In this embodiment, multiple third grooves 123 are provided, allowing the electrolyte to wet both sides through these grooves, further increasing the electrolyte wetting rate, shortening the static wetting time after battery injection, improving production efficiency, and mitigating localized lithium plating issues. At least two third grooves 123 are symmetrically or staggered on opposite sides of a second groove 122, allowing the electrolyte to converge into the second groove 122 via the at least two third grooves 123 and then flow into the first groove 121, thus achieving electrolyte flow.

[0041] According to some embodiments of this application, refer to Figure 1 and Figure 2 One end of the electrode 100 is the starting end of the winding located on the inner ring of the cell after winding, and the other end is the ending end of the winding located on the outer ring of the cell after winding. In the direction from the starting end of winding to the ending end of winding, the spacing between adjacent second grooves 122 gradually increases.

[0042] In this embodiment, one end of the electrode 100 is the winding start end, and the other end is the winding end. After the electrode 100 is wound, the winding start end is wound to the middle of the cell, where it is not easily wetted by the electrolyte. The winding end is located on the outer ring of the cell. To solve the above problems, in the direction from the winding start end to the winding end, the distance between the more than 120 second grooves 122 in the active material layer gradually increases. That is, the distance L1 between two adjacent second grooves 122 near the winding start end is smaller than the distance L2 between two adjacent grooves away from the winding start end. The number of second grooves 122 on the electrode 100 within the same length range near the winding start end is greater, which increases the electrolyte wetting rate to the middle of the cell, shortens the static wetting time after battery electrolyte injection, improves production efficiency, and improves the local lithium plating problem.

[0043] According to some embodiments of this application, refer to Figure 2 In the direction from the starting end of winding to the ending end of winding, the width of the plurality of second grooves 122 gradually decreases.

[0044] Furthermore, the width of the second groove 122 gradually decreases from the starting end of winding to the ending end of winding, that is, the width of the second groove 122 near the starting end of winding is greater than the width of the second groove 122 near the ending end of winding. The wider second groove 122 can accommodate more electrolyte, thereby increasing the wetting rate of the electrolyte outside the second groove 122, so as to solve the problem that the middle of the cell is not easily wetted by electrolyte.

[0045] Based on some embodiments of this application, refer again Figure 2 In the direction from the starting end of winding to the ending end of winding, the depth of the plurality of second grooves 122 gradually decreases.

[0046] Furthermore, the depth of the second groove 122 gradually decreases from the starting end of winding to the ending end of winding, that is, the depth of the second groove 122 near the starting end of winding is greater than the depth of the second groove 122 near the ending end of winding. The wider second groove 122 can accommodate more electrolyte, thereby increasing the wetting rate of the electrolyte outside the second groove 122, so as to solve the problem that the middle of the cell is not easily wetted by electrolyte.

[0047] According to some embodiments of this application, the width ratio of the second groove 122 to the width of the first groove 121 is A, where A satisfies: 0.3 ≤ A ≤ 0.5; and / or, The width of the third groove 123 is B to the width of the second groove 122, and B satisfies: 0.3≤B≤0.5.

[0048] For example, the ratio A between the width of the second groove 122 and the width of the first groove 121 is 0.3, 0.4, or 0.5, or falls within the range of any two of the above values. The width ratio A between the second groove 122 and the first groove 121 should not be too small. According to the Hagen-Poiseuille formula, flow resistance is inversely proportional to the fourth power of the radius. When the width ratio decreases, the flow resistance increases sharply, reducing the actual flow rate of the electrolyte and making it prone to clogging. The width ratio between the second groove 122 and the first groove 121 should also not be too large. An excessively wide second groove 122 will weaken the capillary drive gradient, causing delayed wetting of the electrolyte at the end of the second groove 122 and affecting the electrolyte wetting rate.

[0049] For example, the ratio B between the width of the third groove 123 and the width of the second groove 122 is 0.3, 0.4, or 0.5, or falls within the range of any two of the above values. The width ratio B of the third groove 123 to the second groove 122 should not be too small. According to the Hagen-Poiseuille formula, flow resistance is inversely proportional to the fourth power of the radius. When the width ratio decreases, the flow resistance increases sharply, reducing the actual electrolyte flow rate and making it prone to clogging. The width ratio of the third groove 123 to the second groove 122 should also not be too large. An excessively wide third groove weakens the capillary drive gradient, causing delayed electrolyte wetting at the end of the third groove 123 and affecting the electrolyte wetting rate.

[0050] According to some embodiments of this application, refer to Figure 1 Let the first included angle α be α, and α satisfy: 30°≤α≤90°; and / or, The second included angle β is β, and β satisfies: 30°≤β≤90°.

[0051] For example, the first included angle α between the second groove 122 and the first groove 121 can be 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, or 90°, or fall within the range of any two of the above values. The first included angle α between the second groove 122 and the first groove 121 should not be too small. If the first included angle α is too small, the radius of curvature of the streamline at the junction of the two will be too small, and boundary layer separation will form a low-pressure dead zone, which will hinder the flow of electrolyte.

[0052] For example, the second included angle β between the third groove 123 and the second groove 122 can be 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, or 90°, or fall within the range of any two of the above values. The second included angle β between the third groove 123 and the second groove 122 should not be too small. An excessively small second included angle β will result in a very small streamline curvature radius at the junction of the two grooves, and boundary layer separation will form a low-pressure dead zone, which will hinder the flow of electrolyte.

[0053] 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.

[0054] 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 configuration, the second electrode having the opposite polarity to the first electrode; wherein at least one of the first electrode and the second electrode is an electrode 100 as described above.

[0055] This application also provides an electronic device that includes the electrochemical device described above.

[0056] The electronic device described in this application is not particularly limited and can be applied to any electronic device known in the prior art.

[0057] 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.

[0058] Example 1 1. Preparation of positive electrode sheet The positive electrode material lithium cobalt oxide, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are mixed thoroughly in an N-methylpyrrolidone solvent system at a mass ratio of 98:1.2:0.8. The mixture is then coated onto aluminum foil, dried, rolled, and slit to obtain the positive electrode sheet.

[0059] 2. Preparation of negative electrode sheet The negative electrode material, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are thoroughly mixed in a deionized water solvent system at a mass ratio of 98.1:0.5:0.7:0.7. The mixture is then coated onto copper foil, dried, rolled, and slit to obtain the negative electrode sheet.

[0060] 3. Laser drilling process for the negative electrode sheet. The negative electrode sheet is perforated using a laser. The angle between the second and first grooves is 30°, the width ratio of the second and first grooves is 0.3, the width of the first groove is 200μm, and the width of the second groove is 60μm. The angle between the third and second grooves is 30°, the width ratio of the third and second grooves is 0.3, and the width of the third groove is 18μm.

[0061] 4. Separating membrane A porous PE film with a thickness of 13.5 μm was used.

[0062] 5. Preparation of electrolyte In a dry argon-atmospheric glove box, propylene carbonate (PC), EC, and DEC were mixed in a mass ratio of 1:1:1 to obtain an organic solvent. Lithium salt LiPF6 was then added to the organic solvent, dissolved, and mixed thoroughly to obtain the electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L.

[0063] 6. Preparation of lithium-ion secondary batteries The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes for safety isolation. The electrode assembly is then wound up to form the electrode assembly. The electrode assembly is placed in a packaging shell, electrolyte is injected, and the package is sealed to obtain a lithium-ion secondary battery.

[0064] Examples 2-6 Examples 2-6 use the same preparation method as Example 1, but differ from Example 1 in that the width ratio of the second groove to the first groove, the included angle between the second groove and the first groove, the width ratio of the third groove to the second groove, and the included angle between the third groove and the second groove are different.

[0065] Comparative Example 1 Comparative Example 1 uses the same preparation method as Example 1, except that 17 parallel and equally spaced longitudinal trenches are processed on the negative electrode sheet using laser etching, with a single trench width of 60 μm.

[0066] The parameters of Examples 1-6 and Comparative Example 1 are summarized in Table 1.

[0067] Furthermore, performance tests were conducted on the above embodiments and comparative examples. The test methods are as follows, and the results are recorded in Table 2: Cyclic performance test Lithium-ion batteries were fabricated using the electrode sheets from the embodiments and comparative examples of this application, and tested using the method described in this application. The lithium-ion batteries were repeatedly charged and discharged to calculate their capacity retention rate. First, the lithium-ion batteries were placed in an environment of 25°C for the first charge and discharge cycle. Constant current charging was performed at a charging current of 1C until the upper limit voltage reached 4.5V; then constant current discharging was performed at a discharging current of 0.5C until the final voltage reached 3.0V. This constituted the first charge-discharge cycle, and the discharge capacity of the first cycle was recorded. Then, the above method was repeated for 600 charge-discharge cycles, with the disassembly interface of the lithium-ion battery observed every 200 cycles.

[0068] The performance results show that the lithium-ion secondary batteries in Examples 1-6 did not exhibit lithium plating in 600 cycles of performance testing, while the lithium-ion secondary battery in Comparative Example 1 showed black spots in 400 cycles of performance testing and lithium plating in 600 cycles. This indicates that creating a first groove, a second groove at an angle to the first groove, and a third groove at an angle to the second groove in the active material layer can improve the lithium plating effect.

[0069] 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.

[0070] 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, characterized in that, include: current collector; An active material layer is disposed on one surface of the current collector. The active material layer has a first groove, a second groove, and a third groove. The first groove extends along the length direction of the current collector. One end of the second groove is connected to the first groove, and the other end of the second groove extends outward, forming a first angle between the extension direction of the second groove and the extension direction of the first groove. One end of the third groove is connected to the second groove, and the other end of the third groove extends outward, forming a second angle between the extension direction of the third groove and the extension direction of the second groove.

2. The electrode sheet according to claim 1, characterized in that, The number of second grooves is multiple, and the multiple second grooves are disposed on opposite sides of the first groove. The second grooves on either side of the first groove are distributed at intervals along the extension direction of the first groove.

3. The electrode sheet according to claim 2, characterized in that, The number of the third groove is multiple; At least one of the third grooves is provided on each of the opposite sides of each of the second grooves.

4. The electrode sheet according to claim 2, characterized in that, One end of the electrode is the starting end of the winding located on the inner ring of the battery cell after winding, and the other end is the ending end of the winding located on the outer ring of the battery cell after winding. In the direction from the starting end of the winding to the ending end of the winding, the spacing between adjacent second grooves gradually increases.

5. The electrode sheet according to claim 4, characterized in that, In the direction from the starting end of the winding to the ending end of the winding, the width of the plurality of second grooves gradually decreases.

6. The electrode sheet according to claim 4, characterized in that, In the direction from the starting end of the winding to the ending end of the winding, the depth of the plurality of second grooves gradually decreases.

7. The electrode sheet according to any one of claims 1 to 6, characterized in that, The width of the second groove is A in ratio to the width of the first groove, wherein A satisfies: 0.3 ≤ A ≤ 0.5; and / or, The width of the third groove is B in ratio to the width of the second groove, wherein B satisfies: 0.3≤B≤0.

5.

8. The electrode sheet according to any one of claims 1 to 6, characterized in that, The first included angle is α, where α satisfies: 30°≤α≤90°; and / or, The second included angle is β, and β satisfies: 30°≤β≤90°.

9. 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 8.

10. An electronic device, characterized in that, Includes the electrochemical device as described in claim 9.

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