Current collector, method for producing a current collector, and battery cell

Abstract

The application discloses a current collector, a current collector preparation method and a battery monomer. The current collector comprises a substrate, and a microstructure is arranged on the surface of the substrate and used for being in contact with an active layer. In a direction away from a tab end, the contact area of the substrate and the active layer shows an increasing trend. The application compensates for the reaction rate difference caused by the electron transmission path difference, and ensures the temperature uniformity inside the battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a current collector, a method for preparing the current collector, and a battery cell. Background Technology

[0002] In the field of batteries, high-capacity lithium-ion batteries have larger electrode sizes and higher current densities during operation. The electron transport paths vary in length. In the region near the tab, the electron transport path is relatively short, the impedance is low, and the electrochemical reaction is relatively rapid. In the bottom region far from the tab, the electron transport path is long, the impedance is correspondingly high, and the electrochemical reaction is delayed.

[0003] In related technologies, the difference in electrochemical reaction rate in different regions leads to uneven internal temperature of the battery in practical applications, reducing battery capacity and charge / discharge efficiency, and limiting the further promotion and application of high-capacity lithium-ion batteries. Summary of the Invention

[0004] This application provides a current collector, a current collector preparation method, and a battery cell to at least partially solve the above-mentioned technical problems.

[0005] According to a first aspect of this application, a current collector is provided, comprising: a substrate having microstructures on its surface for contacting an active layer; wherein the contact area between the substrate and the active layer increases in a direction away from the tab end. This arrangement compensates for uneven reaction rates caused by differences in electron transport paths, ensuring temperature uniformity within the battery.

[0006] Optionally, the contact area between the microstructure and the active layer increases in a gradient direction away from the tab end. This gradient structure design reduces heat differences within the battery caused by uneven reactions by optimizing electron transport paths and electrochemical reaction processes.

[0007] Optionally, the microstructure includes groove structures formed on the substrate surface. Groove structures are easy to process and highly standardized, reducing raw material waste and processing time during production, thereby lowering manufacturing costs.

[0008] Optionally, the depth of the groove structure increases in the direction away from the tab end. A groove structure with increasing depth can significantly increase the contact area between the substrate surface and the active layer, thereby improving the utilization rate of the active material.

[0009] Optionally, the depth of the groove structure and the thickness of the substrate satisfy the condition 0.1≤H2 / H1≤0.8. This setting ensures that the substrate has sufficient remaining thickness to maintain its structural strength, while also increasing the contact area between the substrate surface and the active layer, allowing the active substances in the active layer to participate more fully in the electrochemical reaction.

[0010] Optionally, the groove structure includes multiple structural units disposed on the substrate; the distribution density of the structural units increases along the direction away from the tab end. By optimizing the distribution density of the structural units, the temperature uniformity of the battery is improved, and the risk of local overheating is reduced.

[0011] Optionally, the structural unit includes dotted grooves; the distribution density of the dotted grooves increases along the direction away from the tab end. Dotted grooves are easier to control in terms of density distribution. By adjusting the laser processing parameters, the distribution density of the dotted grooves in different areas can be precisely controlled, thereby optimizing battery performance.

[0012] Optionally, the outer diameter of the dotted groove and the thickness of the substrate satisfy the condition 0.05≤D2 / H1≤0.5. This ensures that the substrate has sufficient strength and good electron transport performance, while also ensuring that the dotted groove has suitable dimensions to provide sufficient reaction contact area.

[0013] Optionally, the structural unit includes linear grooves; the distribution density of the linear grooves increases along the direction away from the tab end. Optimizing the distribution density of the linear grooves reduces heat differences caused by uneven reaction and effectively improves the temperature uniformity of the battery.

[0014] Optionally, the width of the linear groove and the thickness of the substrate satisfy 0.1≤D1 / H1≤0.6. This ensures that the substrate has sufficient strength and good electron transport performance, while also ensuring that the linear groove has suitable dimensions to provide sufficient reaction contact area and improve battery performance.

[0015] Optionally, the surface of the substrate is divided into multiple contact regions along the current direction, and the microstructure is distributed in these multiple contact regions; wherein, along the direction away from the tab end, the contact area between the multiple contact regions and the active layer gradually increases. The design of multiple contact regions facilitates processing; by setting parameter programs, processing parameters can be adjusted for each contact region to precisely manufacture the required microstructure, achieving efficient and accurate processing.

[0016] Optionally, the microstructure is disposed in a first region on the substrate surface, and the first region is distributed in the contact area; along the direction away from the tab end, the area ratio of the first region to the corresponding contact area gradually increases. By reasonably controlling the distribution of the first region, uniform current transmission is ensured, and the risk of local overheating is reduced.

[0017] Optionally, the microstructure includes a groove structure disposed in the substrate, wherein the average depth difference of the groove structure in two adjacent contact areas satisfies 0.3μm≤Q1≤3μm. This configuration avoids the problem of reduced substrate structural strength due to excessive average depth difference, while ensuring a certain structural difference between different contact areas, effectively improving the temperature uniformity of the battery.

[0018] Optionally, the microstructure includes structural units disposed in the substrate. In two adjacent contact regions, the difference in the distribution density of the structural units satisfies 0.1 units / mm² ≤ Q² ≤ 2 units / mm². This arrangement avoids the problem of the substrate becoming too thin in the dense structural unit region and the reduction in electron transfer capability due to an excessively large difference in distribution density, while ensuring that there are certain structural differences between different contact regions.

[0019] Optionally, along the direction away from the tab end, the surface of the substrate is sequentially divided into three contact regions along the current direction, with the areas of the three contact regions gradually increasing, and the area ratio of adjacent contact regions being 1:(0.7~1). By setting contact regions with gradually increasing areas, it is possible to better adapt to the temperature change sensitivity of different regions, thereby improving the overall performance and safety of the battery.

[0020] According to two aspects of this application, a method for preparing a current collector is provided, comprising: dynamically adjusting laser parameters and scanning path based on a preset gradient spectrum to form a gradient-distributed microstructure on the surface of a substrate; wherein, along the direction away from the tab end, the distribution density of the microstructure shows an increasing trend, and / or, the depth of the microstructure shows an increasing trend.

[0021] According to three aspects of this application, a battery cell is provided, comprising the current collector described in any one of the above claims.

[0022] By using the aforementioned current collector, the electron transport in the battery cell is more uniform and the electrochemical reaction is more balanced during charging and discharging.

[0023] The current collector in this embodiment of the application adjusts the contact area between different regions of the substrate and the active layer by setting microstructures on the substrate surface. This increases the reaction rate in the region far from the tab end due to the increased contact area, making the reaction rate more consistent with that in the region near the tab end. In other words, this embodiment compensates for the uneven reaction rate caused by differences in electron transport paths, making the electrochemical reaction in each region inside the battery more balanced and ensuring the temperature uniformity inside the battery.

[0024] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0026] Figure 1 This is a front view schematic diagram of the current collector provided in the embodiments of this application; Figure 2 This is a side view of the substrate and active layer provided in the embodiments of this application; Figure 3 This is a side view of the substrate provided in the embodiments of this application; Figure 4 This is a front view schematic diagram of a current collector provided in another embodiment of this application; Figure 5 This is a front view schematic diagram of the structural unit provided in the embodiments of this application; Figure 6 This is a front view schematic diagram of a current collector provided in another embodiment of this application; Figure 7 This is a front view schematic diagram of a current collector provided in another embodiment of this application; Figure 8 This is a front view schematic diagram of a current collector provided in another embodiment of this application.

[0027] Explanation of reference numerals in the attached figures: 1. Current collector; 10. Matrix; 11. Microstructure; 12. Groove structure; 13. Structural unit; 131. Dot groove; 132. Linear groove; 14. Contact area; 141. First region; 20. Ear tip; 30. Active layer. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0029] In the field of batteries, high-capacity lithium-ion batteries have larger electrode sizes and higher current densities during operation. The electron transport paths vary in length. In the region near the tab, the electron transport path is relatively short, the impedance is low, and the electrochemical reaction is relatively rapid. In the bottom region far from the tab, the electron transport path is long, the impedance is correspondingly high, and the electrochemical reaction is delayed.

[0030] In related technologies, the difference in electrochemical reaction rate in different regions leads to uneven internal temperature of the battery in practical applications, reducing battery capacity and charge / discharge efficiency, and limiting the further promotion and application of high-capacity lithium-ion batteries.

[0031] Regarding the above technical issues, firstly, refer to Figure 1 , Figure 2 This application provides a current collector 1, comprising: a substrate 10, the surface of which is provided with a microstructure 11, the microstructure 11 being used to contact an active layer 30; wherein, along the direction away from the tab end 20, the contact area between the substrate 10 and the active layer 30 tends to increase.

[0032] Specifically, the substrate 10 is the main part of the current collector, and its surface is provided with microstructures 11, which are used to contact the active layer 30. The substrate 10 can be made of conventional materials such as copper foil or aluminum foil, which have good conductivity and can meet the requirements of electron transport.

[0033] The tab end 20 is located at one end of the base 10, and its function is to connect to the external circuit of the battery to realize the input and output of current. The material of the tab end 20 is copper, aluminum, etc., and it is integrally formed or welded to the base 10.

[0034] Reference Figure 1 The direction away from the tab end 20 refers to the direction from the upper side to the lower side of the substrate 10 in the drawing, or the direction from the tab end 20 of the substrate 10 to the other end opposite to the tab end 20.

[0035] The microstructure 11 is formed on the surface of the substrate 10 by etching methods such as laser processing and chemical processing, forming a groove structure 12; it can also be formed on the surface of the substrate 10 by bonding, welding, or integral molding, forming a raised structure. The shape, size, and distribution of the microstructure 11 can be adjusted according to actual needs. The microstructure 11 is distributed in different areas of the substrate 10, so that the surface of the substrate 10 and the active layer 30 form a three-dimensional contact surface, thereby increasing the contact area.

[0036] During the operation of a lithium-ion battery, electrons are transported through the current collector. When the battery is charging, electrons are released from the positive electrode active material, transported through the current collector 1 to the tab end 20, and then flow to the negative electrode through the external circuit. When discharging, the opposite occurs: electrons enter the current collector 1 from the negative electrode through the external circuit and the tab end 20, and then embed themselves into the positive electrode active material.

[0037] Along the direction away from the tab end 20, by adjusting the morphology, size, and distribution of the microstructures 11, the contact area between the substrate 10 and the active layer 30 can be increased. For example, in the region near the tab end 20, the distribution of the microstructures 11 is relatively sparse, resulting in a relatively small contact area between the substrate 10 and the active layer 30 in this region; while in the region away from the tab end 20, the distribution of the microstructures 11 is dense, resulting in a relatively large contact area between the substrate 10 and the active layer 30.

[0038] During electron transport, the region near the tab end 20 has a short electron transport path and low impedance, allowing the electrochemical reaction to proceed rapidly. In the region far from the tab end 20, although the electron transport path is originally long and the impedance is high, the large contact area between the substrate 10 and the active layer 30 and the enhanced electron supply by the microstructure 11 gradually increase the utilization rate and reaction rate of the active material, thereby offsetting the adverse effects of the long electron transport path to a certain extent.

[0039] In this embodiment, the current collector 1, by setting microstructures 11 on the surface of the substrate 10, adjusts the contact area between different regions of the substrate 10 and the active layer 30, so that the reaction rate of the region far from the tab end 20 increases due to the increased contact area, and the reaction rate of the region near the tab end 20 tends to be consistent; that is, this embodiment compensates for the uneven reaction rate caused by the difference in electron transport path, so that the electrochemical reaction in each region inside the battery is more balanced, and the temperature uniformity inside the battery is guaranteed.

[0040] In some embodiments, reference Figure 3 , Figure 4 Along the direction away from the tab end 20, the contact area between the microstructure 11 and the active layer 30 increases in a gradient.

[0041] Specifically, the microstructure 11 is distributed in a gradient on the substrate 10. For example, the shape and size of the microstructure 11 vary in a gradient. The microstructure 11 is a groove structure 12, and the depth of the groove structure 12 gradually increases in the direction away from the tab end 20.

[0042] For example, the microstructure 11 consists of multiple structural units 13. The distribution density of the multiple structural units 13 varies with gradient. In the region near the tab end 20, the distribution of the microstructure 11 is relatively sparse, and the number of microstructures per unit area is small. However, as the distance from the tab end 20 increases, the distribution of the microstructure 11 gradually becomes denser, and the number of microstructures per unit area increases.

[0043] The gradient structure design in this embodiment optimizes the electron transport path and electrochemical reaction process, reducing the heat difference caused by uneven reaction inside the battery, thereby improving the battery's safety and lifespan.

[0044] In some embodiments, reference Figure 1 The microstructure 11 includes a groove structure 12 formed on the surface of the substrate 10.

[0045] Specifically, in this embodiment, the groove structure 12 is distributed in different regions of the substrate 10, and its shape, size, and distribution can be flexibly adjusted according to actual needs. By reasonably adjusting these parameters of the groove structure 12 along the direction away from the tab end 20, the contact area between the substrate 10 and the active layer can be increased. For example, in the region near the tab end 20, the groove structure 12 is relatively sparsely distributed, resulting in a smaller contact area between the substrate 10 and the active layer 30 in this region; while in the region away from the tab end 20, the groove structure 12 is densely distributed, resulting in a larger contact area between the substrate 10 and the active layer 30.

[0046] Compared to raised structures, groove structures 12 have significant advantages in the processing. When using laser etching, groove structures 12 are easier to precisely process by controlling laser parameters. For example, during laser processing, only the laser focus point, power, and scanning speed need to be adjusted to form groove structures 12 of different depths and paths on the surface of the substrate 10. The operation is relatively simple and the requirements for processing equipment are relatively low.

[0047] Furthermore, since the groove structure 12 is easy to process and highly standardized, it can reduce the waste of raw materials and the consumption of processing time during the production process, thereby reducing manufacturing costs.

[0048] In some embodiments, reference Figure 3 Along the direction away from the tab end 20, the depth of the groove structure 12 tends to increase.

[0049] refer to Figure 3 The depth of the groove structure 12 is represented by the value of H2. The increasing depth of the groove structure 12 indicates that the value of H2 is increasing.

[0050] Specifically, the groove structure 12 is shallower near the tab end 20; as the distance from the tab end 20 increases, the depth of the groove structure 12 gradually increases. This increasing depth of the groove structure 12 significantly increases the contact area between the substrate 10 and the active layer 30. During battery operation, electrons need to be transported between the substrate 10 and the active layer 30. A larger contact area increases the channels for electron transport, allowing electrons to move more smoothly between the two, thereby improving the utilization rate of the active material.

[0051] The depth of the groove structure 12 can be varied by adjusting laser processing parameters, such as laser power and scanning speed, to precisely control the depth of the groove structure 12 at different positions. During production, a suitable depth distribution of the groove structure 12 can be obtained according to different requirements, exhibiting high flexibility. This flexibility allows the groove structure 12 to be customized to meet the needs of different types of current collectors 1, improving the versatility and adaptability of production.

[0052] Furthermore, laser processing is characterized by high processing speed and high precision, which improves production efficiency. At the same time, due to the high controllability of the processing, the defect rate is reduced, further lowering production costs.

[0053] In some embodiments, reference Figure 3 The depth H2 of the groove structure 12 and the thickness H1 of the substrate 10 satisfy 0.1≤H2 / H1≤0.8.

[0054] Specifically, when H2 / H1 is less than 0.1, the depth of the groove structure 12 is too small, and its effect on increasing the contact area between the substrate 10 and the active layer 30 is not significant. If the depth H2 of the groove structure 12 is too large, i.e., H2 / H1 > 0.8, the local remaining thickness of the substrate 10 is too thin, which will lead to a significant decrease in the structural strength of the substrate 10. The substrate 10 with insufficient structural strength is prone to deformation, breakage, and other problems, affecting the overall performance and safety of the battery.

[0055] In this embodiment, the groove structure 12 has a suitable depth within the ratio range of 0.1 ≤ H2 / H1 ≤ 0.8. This ensures that the substrate 10 has sufficient remaining thickness to maintain its structural strength, while also increasing the contact area between the surface of the substrate 10 and the active layer 30, allowing the active substances in the active layer 30 to participate more fully in the electrochemical reaction.

[0056] In some embodiments, reference Figure 4 , Figure 5 The groove structure 12 includes a plurality of structural units 13 disposed on the substrate 10; the distribution density of the structural units 13 increases along the direction away from the tab end 20.

[0057] Specifically, the structural unit 13 is an independent unit, which can be a single dot groove 131, such as tiny dimples evenly distributed on the surface of the substrate 10; or a single line groove 132, such as slender lines engraved on the surface of the substrate 10; or a simple pattern formed by combining multiple line grooves, such as a fork, triangle, hexagon, or other pattern.

[0058] Dotted grooves, line grooves, and various patterns can all be achieved by precisely setting the laser power and path parameters. Through laser etching, multiple repeating structural units 13 can be formed on the surface of the substrate 10. Furthermore, the distribution density of the structural units 13 increases along the direction away from the tab end 20. That is, in the region near the tab end 20, the distribution of structural units 13 is relatively sparse; as the distance from the tab end 20 increases, the number of structural units 13 gradually increases, and the distribution becomes denser.

[0059] This embodiment improves the temperature uniformity of the battery and reduces the risk of local overheating by optimizing the distribution density of structural unit 13.

[0060] In some embodiments, reference Figure 6 The structural unit 13 includes dot-shaped grooves 131; the distribution density of the dot-shaped grooves 131 increases along the direction away from the tab end 20.

[0061] Specifically, the dotted groove 131 is a pit with a certain area, and its shape is circular or irregular. The dotted groove 131 is evenly distributed on the surface of the substrate 10, and the distribution density of the dotted groove 131 increases along the direction away from the tab end 20. That is to say, in the area near the tab end 20, the distribution of the dotted groove 131 is relatively sparse; as the distance from the tab end 20 increases, the number of dotted grooves 131 gradually increases and the distribution becomes denser.

[0062] The dotted grooves 131 are processed using laser etching, which offers high flexibility and precision. By precisely setting the laser's function and path parameters, such as power, pulse frequency, and scanning speed, dotted grooves 131 of the required shape, size, and distribution density can be accurately processed on the surface of the substrate 10.

[0063] In this embodiment, the structural unit 13 is specifically set as a dotted groove 131. The density distribution of the dotted groove 131 is easier to control. By adjusting the laser processing parameters, such as scanning speed and pulse frequency, the distribution density of the dotted groove 131 in different areas can be precisely controlled.

[0064] In some embodiments, reference Figure 6 The outer diameter D2 of the dotted groove 131 and the thickness H1 of the base 10 satisfy 0.05≤D2 / H1≤0.5.

[0065] Specifically, the outer circle diameter D2 of the dotted groove 131 and the thickness H1 of the base 10 satisfy 0.05≤D2 / H1≤0.5, for example 0.05, 0.1, 0.2, 0.3, 0.05.

[0066] If the ratio of the outer diameter D2 of the dotted groove 131 to the thickness H1 of the substrate 10 is too large, that is, D2 is too large relative to H1, when the dotted groove 131 is densely distributed on the surface of the substrate 10, it will cause the local area of ​​the substrate 10 to be too thin, which will reduce the structural strength of the substrate 10 and make it easy to deform and break. In addition, the excessively dense distribution will require higher processing accuracy and processing time, which will increase the manufacturing difficulty and cost.

[0067] When the ratio of the outer diameter D2 of the dotted groove 131 to the thickness H1 of the substrate 10 is too small, that is, D2 is too small relative to H1, the size of the dotted groove 131 will be too small. At this time, the contact area between the dotted groove 131 and the active material in the active layer 30 is limited, and the improvement of reaction efficiency is not significant. This embodiment, by reasonably limiting the range of D2 / H1, ensures that the substrate 10 has sufficient strength and good electron transport performance, and also ensures that the dotted groove 131 has a suitable size to provide sufficient reaction contact area.

[0068] In some embodiments, reference Figure 7 The structural unit 13 includes linear grooves 132; the distribution density of the linear grooves 132 increases along the direction away from the tab end 20.

[0069] Specifically, the linear groove 132 is presented as a linear groove.

[0070] The extension direction of the multiple linear grooves 132 is flexible. They can be kept in the same direction, that is, all the linear grooves 132 extend in the same direction to form a neat and orderly arrangement; or they can intersect each other, for example, some of the linear grooves 132 extend laterally and some extend longitudinally, thereby forming an intersecting grid structure on the surface of the substrate 10.

[0071] There are two distribution patterns for the linear grooves 132. On the one hand, they can be distributed as independent units in an array on the surface of the substrate 10. This array distribution can be regular, such as evenly spaced, or irregular, depending on actual needs. On the other hand, multiple linear grooves 132 can be combined to form simple patterns, such as forks, triangles, hexagons, etc., and then these simple patterns can be distributed in an array on the surface of the substrate 10.

[0072] Along the direction away from the tab end 20, the distribution density of the linear grooves 132 shows an increasing trend. In the region close to the tab end 20, the linear grooves 132 are relatively sparsely distributed, with fewer linear grooves 132 per unit area; while as the distance from the tab end 20 increases, the number of linear grooves 132 gradually increases, and the distribution becomes denser.

[0073] In this embodiment, by optimizing the distribution density of the linear grooves 132, the reaction rate in the region far from the tab end 20 is increased, and the reaction rate in the region close to the tab end 20 is made more consistent. This equalization of the reaction rate makes the electrochemical reactions in different regions inside the battery more synchronized, reduces the heat difference caused by uneven reaction, and effectively improves the temperature uniformity of the battery.

[0074] In some embodiments, the width D1 of the linear groove 132 and the thickness H1 of the substrate 10 satisfy 0.1≤D1 / H1≤0.6.

[0075] Specifically, the value of D1 / H1 can be 0.1, 0.2, 0.3, 0.4, 0.6, etc.

[0076] If D1 / H1 is too large, the width of the linear groove 132 will be too wide relative to the thickness of the substrate 10. When machining the linear groove 132, an excessively wide groove will increase machining difficulty and affect machining accuracy. Furthermore, when the linear grooves 132 are densely distributed on the surface of the substrate 10, it will cause local areas of the substrate 10 to become too thin, significantly increasing the resistance in these areas and increasing electron transport resistance, making it difficult for electrons to pass through smoothly, thereby reducing electron transfer capacity and reaction efficiency.

[0077] If D1 / H1 is too small, the linear groove 132 will be too narrow, and the contact area between the linear groove 132 and the active material in the active layer 30 will be limited, resulting in no significant improvement in reaction efficiency.

[0078] This embodiment, by reasonably limiting the range of D1 / H1, ensures that the substrate 10 has sufficient strength and good electron transport performance, and also ensures that the linear groove 132 has appropriate size to provide sufficient reaction contact area.

[0079] In some embodiments, reference Figure 1 , Figure 4 , Figure 6 The surface of the substrate 10 is divided into multiple contact regions 14 along the current direction, and the microstructure 11 is distributed in the multiple contact regions 14; wherein, along the direction away from the tab end 20, the contact area between the multiple contact regions 14 and the active layer 30 gradually increases.

[0080] Specifically, along the direction of the current, the surface of the substrate 10 is divided into multiple contact regions 14, and the number of contact regions 14 can be, for example, 2 to 5.

[0081] To achieve variations in contact area, the microstructures 11 within each contact region 14 differ significantly in morphology, size, and structure. For example, in the first contact region 14 near the tab end 20, the microstructures 11 may be relatively small and sparse dot-like grooves; while as the distance from the tab end 20 increases, the microstructures 11 in subsequent contact regions 14 gradually become larger and denser linear grooves 132 or protrusions, thereby gradually increasing the contact area.

[0082] The design of multiple contact areas 14 in this embodiment brings convenience to the processing. Since the microstructures 11 in different contact areas 14 have different characteristics, the processing parameters, such as laser power, processing speed, and processing path, can be adjusted for each contact area 14 by setting parameter programs during the processing to accurately manufacture the required microstructures 11 and achieve efficient and precise processing.

[0083] In some embodiments, reference Figure 8 The microstructure 11 is disposed on a first region 141 on the surface of the substrate 10, and the first region 141 is distributed in the contact region 14; along the direction away from the tab end 20, the area ratio of the first region 141 to the corresponding contact region 14 gradually increases.

[0084] Specifically, the surface of the substrate 10 is divided into multiple contact regions 14 along the current direction. Within each contact region 14, a first region 141 is further provided, and the microstructure 11 is specifically disposed within the first region 141.

[0085] The first region 141 is part of the contact region 14, and its number is flexible; one or more can be set in each contact region 14. Furthermore, these first regions 141 can be discretely distributed within each contact region 14. For example, in the contact region 14 near the tab end 20, only one relatively small first region 141 may be provided; as the number of first regions 141 in subsequent contact regions 14 increases, or the area of ​​a single first region 141 increases, or both change simultaneously, along the direction away from the tab end 20, ultimately causing the area ratio of the first region 141 to the corresponding contact region 14 to gradually increase.

[0086] This embodiment ensures uniform current transmission and reduces the risk of localized overheating by rationally controlling the distribution of the first region 141. Furthermore, by flexibly setting the number, distribution density, and area of ​​the first region 141, the structure of the current collector can be customized according to the performance requirements and usage scenarios of different types of batteries.

[0087] In some embodiments, the microstructure 11 includes a groove structure 12 disposed on the substrate 10, wherein in two adjacent contact regions 14, the average depth difference Q1 of the groove structure 12 satisfies 0.3μm≤Q1≤3μm.

[0088] Specifically, the average depth difference Q1 is 0.3μm≤Q1≤3μm, for example, it can be 0.3μm, 0.7μm, 1.3μm, 2.3μm, 3μm, etc.

[0089] If the average depth difference gradient of the groove structures 12 in adjacent contact areas 14 is too large, it will adversely affect the structural strength of the substrate 10. Excessive depth difference can lead to a significant decrease in the structural strength of the substrate 10, making it prone to deformation and breakage, thus affecting the overall performance and safety of the battery. Furthermore, excessive depth difference increases processing difficulty, requiring more sophisticated processing equipment and processes, thus increasing production costs. Conversely, if the average depth difference gradient of the groove structures 12 in adjacent contact areas 14 is too small, the advantages of this structural design cannot be fully utilized, and the improvement effect on temperature uniformity is not significant.

[0090] In some embodiments, the microstructure 11 includes structural units 13 disposed on the substrate 10, and the difference Q2 in the distribution density of the structural units 13 in two adjacent contact regions 14 satisfies 0.1 units / mm² ≤ Q2 ≤ 2 units / mm².

[0091] Specifically, the value of Q2 can be 0.1, 0.2, 0.3, 1, 2, etc.

[0092] If Q2 is too large, that is, the difference in the distribution density of structural units 13 in two adjacent contact areas 14 is too large, it will lead to a significant increase in the amount of local material removal on the surface of the substrate 10 in the area where structural units 13 are densely distributed, which will reduce the structural strength of the substrate 10 and make it prone to deformation and fracture. In addition, an excessively large density gradient requires higher processing accuracy and processing time, which increases the manufacturing difficulty and cost.

[0093] If Q2 is too small, that is, the distribution density difference of structural unit 13 in two adjacent contact areas 14 is not obvious, then the difference in heat conduction and electron transport between different areas will also be small, the regulating effect on the current collector will be weakened, and the temperature equalization effect will not be obvious.

[0094] This embodiment controls the distribution density difference Q2 of structural units 13 in two adjacent contact areas 14 within a reasonable range of 0.1 units / mm² to 2 units / mm². This avoids the problem of the substrate 10 in the dense area of ​​structural units 13 being too thin and the electron transfer capability decreasing due to excessive Q2, while ensuring that there are certain structural differences between different contact areas 14.

[0095] In some embodiments, reference Figure 8 Along the direction away from the tab end 20, the surface of the substrate 10 is divided into three contact regions 14 in sequence along the current direction. The area of ​​the three contact regions 14 gradually increases, and the area ratio of adjacent contact regions 14 is 1:0.7 to 1.

[0096] Specifically, the surface of the substrate 10 is divided into three contact regions 14 along the current direction, denoted as A, B, and C. The areas of these three contact regions 14 gradually increase in the direction away from the tab end 20, i.e., from near the tab end 20 to far away from it. Furthermore, the area ratio of adjacent contact regions 14 is set within the range of 1:0.7 to 1. For example, if the area of ​​contact region A is S1, the area of ​​contact region B is S2, and the area of ​​contact region C is S3, then S1:S2 = 1:a, S2:S3 = 1:b, where 0.7 ≤ a ≤ 1, and 0.7 ≤ b ≤ 1.

[0097] The area near the tab end 20 is a region of dense current, generating more heat and experiencing rapid temperature gradient changes; while the area far from the tab end 20 has a relatively low current density due to the continuous dispersion of current during transmission, resulting in less heat generation and slower temperature gradient changes.

[0098] This embodiment sets up a contact area 14 with a gradually increasing area, that is, the area near the tab end 20 is relatively small and the area away from the tab end 20 is relatively large, which can better adapt to the temperature change sensitivity of different areas.

[0099] Secondly, embodiments of this application provide a method for preparing a current collector, comprising: dynamically adjusting laser parameters and scanning path according to a preset gradient spectrum to form a gradient-distributed microstructure 11 on the surface of a substrate 10; wherein, along the direction away from the tab end 20, the distribution density of the microstructure 11 shows an increasing trend, and / or, the depth of the microstructure 11 shows an increasing trend.

[0100] Specifically, based on battery design requirements, a gradient distribution pattern of microstructures 11 on the surface of the substrate 10 is pre-designed. The gradient pattern clarifies the trend of the distribution density and / or depth of microstructures 11 along the direction away from the tab end 20. For example, it can be set that the microstructures 11 are sparsely distributed and shallowly deep in the region near the tab end 20, and densely distributed and deeply deep in the region away from the tab end 20.

[0101] Based on the preset gradient spectrum, the laser parameters, such as power, pulse frequency, scanning speed, and scanning path, are dynamically adjusted using laser processing equipment; etching is then performed on the surface of the substrate 10 to form the required microstructure 11.

[0102] During laser processing, the morphology, size, and distribution of microstructures 11 can be precisely adjusted by controlling the laser parameters. For example, in areas where a dense distribution of microstructures 11 is required, the laser power can be increased or the scanning speed can be decreased; in areas where a greater depth of microstructures 11 is required, the depth of the laser focal point can be increased or the laser action time can be extended.

[0103] After laser processing, microstructures 11 are formed on the surface of the substrate 10 in a gradient distribution along the direction away from the tab end 20; the microstructures 11 can be groove structures 12, or structural units 13 such as dot grooves 131 and line grooves 132, or combinations thereof.

[0104] The gradient distribution of the microstructure 11 causes the contact area between the substrate 10 and the active layer 30 to increase in the direction away from the tab end 20, thereby improving the uniformity of the electrochemical reaction inside the battery and ensuring the temperature uniformity inside the battery.

[0105] Thirdly, embodiments of this application provide a battery cell including the current collector 1 as described in any of the above claims; it also includes a casing, an active layer 30, and an electrolyte.

[0106] The active layer 30 includes a positive electrode active material and a negative electrode active material. The active layer 30 is in close contact with the substrate 10 to enable electron transport.

[0107] During the charging process of a single battery cell, electrons are released from the positive electrode active material, transported through the substrate 10 to the tab end 20, and then flow to the negative electrode through the external circuit. Simultaneously, lithium ions are released from the positive electrode, migrate through the electrolyte and separator to the negative electrode, and embed themselves in the negative electrode active material. The discharge process is the opposite: electrons enter the substrate 10 from the negative electrode via the external circuit and the tab end 20, and then embed themselves in the positive electrode active material; lithium ions, on the other hand, are released from the negative electrode and migrate back to the positive electrode.

[0108] The solution of this application will be verified through several specific embodiments below.

[0109] Example 1 Zoning method: Zone A (proximal ear tip), Zone B (middle), Zone C (bottom), with an area ratio of 3:4:4.

[0110] Groove depth: consistent throughout, 2μm.

[0111] Distribution density of structural units (linear grooves): Area A: 2 per mm²; Zone B: 3 per mm²; Zone C: 4 per mm².

[0112] Example 2 Partitioning method: Same as in Example 1.

[0113] Structural unit (linear groove) distribution density: consistent throughout the area, 3 units / mm².

[0114] Groove depth: Area A: 1.0μm; Zone B: 2.0μm; Region C: 3.0μm.

[0115] Example 3 Partitioning method: Same as Example 1 Groove depth: Area A: 1.0μm; Zone B: 2.0μm; Region C: 3.0μm.

[0116] Structural unit (linear groove) distribution density: Area A: 2 per mm²; Zone B: 3 per mm²; Zone C: 4 per mm².

[0117] Comparative Example 1 The substrate surface is smooth and free of any microstructure. Comparative Example 2 Groove depth: Area A: 2.0μm; Region B: 2.1μm; Region C: 2.2μm.

[0118] Comparative Example 3 Structural unit (linear groove) distribution density: Area A: 3.0 pieces / mm²; Zone B: 3.1 per mm²; Zone C: 3.2 per mm².

[0119] Comparative Example 4 Groove depth: Area A: 1.0μm; Zone B: 5.0μm; Region C: 10.0μm.

[0120] Comparative Example 5 Structural unit (linear groove) distribution density: Area A: 1 unit / mm²; Zone B: 8 per mm²; Zone C: 15 per mm².

[0121] Based on the above embodiments and comparative examples, a 2C rate charging test was conducted on the current collector design. The impact of different designs on the internal temperature uniformity of the battery was evaluated by measuring the temperature difference between the upper and lower parts of the substrate 10. The following are the experimental data:

[0122] Table 1 According to the results of Comparative Example 1, the lack of microstructure design leads to varying electron transport paths in the current collector, high electron transport impedance in regions far from the tab, delayed electrochemical reactions, and significant temperature differences.

[0123] According to the results of Comparative Example 2, if the depth gradient design is too small, it is difficult to effectively compensate for the differences in electron transport paths, and its effect on improving the temperature uniformity of the current collector is limited.

[0124] According to the results of Comparative Example 3, if the density gradient design is too small, it is difficult to effectively compensate for the differences in electron transport paths, and its effect on improving the temperature uniformity of the current collector is limited.

[0125] According to the results of Comparative Example 4, although a large depth gradient can improve temperature uniformity, an excessively large depth gradient design reduces the structural strength of the matrix and increases the processing difficulty and manufacturing cost.

[0126] According to the results of Comparative Example 5, although a large density gradient can improve temperature uniformity, an excessively large density gradient design reduces the structural strength of the matrix and increases the processing difficulty and manufacturing cost.

[0127] As can be seen from the results of Example 1, the temperature uniformity of the current collector was improved by reasonably setting the distribution density gradient of the structural units.

[0128] As can be seen from the results of Example 2, by reasonably setting the depth gradient of the groove structure, the temperature uniformity of the current collector is improved.

[0129] As shown in the results of Example 3, the combined design of density gradient and depth gradient significantly reduced the temperature difference of the current collector through synergistic effect, achieving optimal electrochemical reaction uniformity and temperature uniformity. At the same time, both the depth gradient and density gradient remained in a low range, reducing processing difficulty and enhancing structural stability.

[0130] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0131] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0132] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0133] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A current collector (1), characterized in that, include: A substrate (10) having a microstructure (11) on its surface, the microstructure (11) being used to contact the active layer (30); In particular, along the direction away from the tab end (20), the contact area between the substrate (10) and the active layer (30) tends to increase.

2. The current collector (1) according to claim 1, characterized in that, Along the direction away from the tab end (20), the contact area between the microstructure (11) and the active layer (30) increases in a gradient.

3. The current collector (1) according to claim 1, characterized in that, The microstructure (11) includes a groove structure (12) formed on the surface of the substrate (10).

4. The current collector (1) according to claim 3, characterized in that, The depth of the groove structure (12) increases in the direction away from the tab end (20).

5. The current collector (1) according to claim 3, characterized in that, The depth H2 of the groove structure (12) and the thickness H1 of the substrate (10) satisfy 0.1≤H2 / H1≤0.

8.

6. The current collector (1) according to claim 3, characterized in that, The groove structure (12) includes a plurality of structural units (13) disposed on the substrate (10); Along the direction away from the tab end (20), the distribution density of the structural unit (13) tends to increase.

7. The current collector (1) according to claim 6, characterized in that, The structural unit (13) includes dotted grooves (131); Along the direction away from the tab end (20), the distribution density of the dotted grooves (131) tends to increase.

8. The current collector (1) according to claim 7, characterized in that, The outer diameter D2 of the dotted groove (131) and the thickness H1 of the base (10) satisfy 0.05≤D2 / H1≤0.

5.

9. The current collector (1) according to claim 6, characterized in that, The structural unit (13) includes a linear groove (132); Along the direction away from the tab end (20), the distribution density of the linear grooves (132) tends to increase.

10. The current collector (1) according to claim 9, characterized in that, The width D1 of the linear groove (132) and the thickness H1 of the substrate (10) satisfy the condition 0.1≤D1 / H1≤0.

6.

11. The current collector (1) according to any one of claims 1 to 10, characterized in that, Along the direction away from the tab end (20), the surface of the substrate (10) is sequentially divided into multiple contact areas (14), and the microstructure (11) is distributed in multiple contact areas (14); Among them, the contact area between the multiple contact areas (14) and the active layer (30) shows an increasing trend.

12. The current collector (1) according to claim 11, characterized in that, Includes at least one of the following: a1) Within each contact area (14), the ratio of the area where the microstructure (11) is provided to the total area of ​​the corresponding contact area (14) gradually increases in the direction away from the tab end (20); a2) The microstructure (11) includes a groove structure (12) disposed on the substrate (10). In two adjacent contact areas (14) along the direction away from the tab end (20), the average depth difference Q1 of the groove structure (12) satisfies 0.3μm≤Q1≤3μm. a3) The microstructure (11) includes structural units (13) disposed on the substrate (10). In two adjacent contact areas (14) along the direction away from the tab end (20), the difference Q2 of the distribution density of the structural units (13) satisfies 0.1 units / mm² ≤ Q2 ≤ 2 units / mm². a4) The surface of the substrate (10) is divided into three contact areas (14) along the current direction. The area of ​​the three contact areas (14) gradually increases along the direction away from the tab end (20), and the area ratio of adjacent contact areas (14) is 1:(0.7~1).

13. A method for preparing a current collector, characterized in that, include: Microstructures (11) are formed on the surface of a substrate (10) by laser processing. The distribution density of the microstructures (11) increases along the direction away from the tab end (20) of the current collector (1), and / or the depth of the microstructures (11) increases.

14. A single battery cell, characterized in that, Includes the current collector (1) as described in any one of claims 1 to 12.

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