A composite current collector with temperature-responsive active circuit breaking function, its preparation method, electrode and battery

Abstract

This application provides a composite current collector with temperature-responsive active circuit breaking function, its preparation method, electrode, and battery, belonging to the field of composite current collector manufacturing technology. The composite current collector includes a polymer matrix and a metal layer. Along the width direction of the polymer matrix, the polymer matrix includes a coating region matrix, a tab region matrix, and a temperature-responsive region matrix located between the two. The temperature-responsive region matrix is ​​filled with an expanding agent. In the thickness direction of the polymer matrix, at least one side of the temperature-responsive region matrix has an inwardly recessed portion. In the thickness direction, both sides of the polymer matrix have metal layers, and the metal layer on the recessed portion side includes a first metal layer located within the recessed portion and a second metal layer located outside the recessed portion. The thickness of the first metal layer is less than the thickness of the second metal layer. This composite current collector has the advantages of high circuit breaking reliability and fast response speed during abnormal temperature rise.

Description

Technical Field

[0001] This application relates to the field of composite current collector manufacturing technology, and more specifically, to a composite current collector with temperature-responsive active circuit breaking function, its preparation method, electrode, and battery. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles and consumer electronics due to their high energy density and long cycle life. Among them, composite current collectors, compared to traditional metal foil current collectors, have gained widespread attention and become a current research hotspot due to their "sandwich" structure (polymer layer + double-sided metal layer), which offers advantages such as light weight and high puncture resistance. However, battery safety remains a key factor restricting its development, especially under overcharging, short circuit, or high-temperature conditions, where batteries are prone to thermal runaway, potentially leading to fire and explosion.

[0003] To address the aforementioned technical problems, engineers typically fill a polymer matrix with an expanding agent, utilizing the rapid expansion of the expanding agent upon heating to apply pressure to the metal layer and achieve a short circuit, as illustrated in patents CN 117525431 A and CN116111104 B. However, existing techniques suffer from insufficient circuit breaking reliability and slow response speed. Therefore, there is an urgent need to design a novel composite current collector with high circuit breaking reliability and fast response speed. Summary of the Invention

[0004] The purpose of this application is to provide a composite current collector with temperature-responsive active circuit breaking function, its preparation method, electrode and battery. The composite current collector has the advantages of high circuit breaking reliability and fast response speed when abnormal temperature rises.

[0005] The embodiments of this application are implemented as follows: In a first aspect, embodiments of this application provide a composite current collector with a temperature-responsive active circuit breaking function, comprising a polymer matrix and a metal layer. Along the width direction of the polymer matrix, the polymer matrix includes a coating region matrix, a tab region matrix, and a temperature-responsive region matrix located between the two. The temperature-responsive region matrix is ​​filled with an expanding agent. In the thickness direction of the polymer matrix, at least one side of the temperature-responsive region matrix has an inwardly recessed portion. In the thickness direction, both sides of the polymer matrix have metal layers, and the metal layer located on the recessed portion side includes a first metal layer located inside the recessed portion and a second metal layer located outside the recessed portion, wherein the thickness of the first metal layer is less than the thickness of the second metal layer.

[0006] In the above technical solution, the temperature response zone matrix is ​​sealed and filled with an expanding agent. In the thickness direction of the polymer matrix, at least one side of the temperature response zone matrix has an inwardly recessed portion. When the composite current collector encounters abnormal temperature rise (e.g., overcharging, short circuit, or high-temperature environment), the expanding agent rapidly expands and applies pressure to the metal layer in the adjacent recess in the thickness direction, causing the metal layer in that area to break, thus achieving circuit breaking. Simultaneously, the thickness of the first metal layer in the recess is less than the thickness of the second metal layer, making it easier for the first metal layer to break under the pressure applied by the expanding agent. Furthermore, the presence of the recess makes the distance between the thinner first metal layer and the expanding agent closer, thus allowing the first metal layer to be subjected to greater pressure during the expanding agent's expansion process (making it easier to break). In addition to setting an expanding agent in the polymer matrix, the technical solution provided in this application also simultaneously adjusts the thickness and position of the first metal layer corresponding to the expanding agent (specifically, the first metal layer is thinner and closer to the expanding agent), i.e., achieving circuit breaking through multiple mechanisms in synergy, so that the composite current collector has the advantages of high circuit breaking reliability and fast response speed during abnormal temperature rise.

[0007] In some alternative implementations, the temperature response region substrate has recesses on both sides in the thickness direction.

[0008] In the above technical solution, the temperature response region matrix has recesses on both sides in the thickness direction. Correspondingly, the metal layers on both sides of the polymer matrix include a first metal layer located inside the recess and a second metal layer located outside the recess. The thickness of the first metal layer is less than the thickness of the second metal layer. That is, both sides of the temperature response region matrix have regions with multiple mechanisms for synergistic circuit breaking. When the temperature rises abnormally, both sides of the temperature response region matrix can achieve circuit breaking, which can further improve the high reliability and response speed of the composite current collector during abnormal temperature rise.

[0009] In some alternative embodiments, the room temperature impact toughness of the first metal layer is less than that of the second metal layer; or / and, the resistivity of the first metal layer is higher than that of the second metal layer.

[0010] In the above technical solution, the room temperature impact toughness of the first metal layer is set to be lower than that of the second metal layer, meaning the first metal layer has poor ductility and high brittleness. This achieves a triple circuit breaking mechanism based on "location + thickness + material," enabling the first metal layer to break more quickly and easily when subjected to pressure from the expanding agent. Furthermore, the resistivity of the first metal layer is set to be higher than that of the second metal layer. During abnormal heating, the temperature of the first metal layer rises faster, allowing it to more rapidly transfer the high temperature to the adjacent expanding agent and achieve rapid circuit breaking through the expansion of the expanding agent.

[0011] In some alternative embodiments, the material of the first metal layer is selected from at least one of copper alloy, nickel-chromium alloy, titanium and stainless steel, and the material of the second metal layer is selected from at least one of copper, aluminum and silver.

[0012] In the above technical solutions, there are many ways to combine the first metal layer and the second metal layer, which can provide a lot of feasible solutions, thereby facilitating the promotion and application of the technical solutions provided in the embodiments of this application.

[0013] In some alternative embodiments, the recess has a V-shaped profile, and in the thickness direction, the thickness of the first metal layer gradually increases from the bottom side of the recess to the opening side; or / and, the thickness of the first metal layer is D1, the thickness of the second metal layer is D2, and the ratio of D1 to D2 is (0.1~0.95):1.

[0014] In the above technical solution, the contour shape of the recess is set to V-shape, and the thickness of the first metal layer gradually increases from the bottom side of the recess to the opening side, that is, the thickness of the first metal layer is in a gradual form. On the one hand, the thickness of the first metal layer near the expanding agent is thinner, making it easier to break the first metal layer in this area. On the other hand, the thickness of the side where the first metal layer connects to the second metal layer is thicker, which can increase the stability and reliability of the connection between the two. By limiting the ratio of the thickness of the first metal layer to the thickness of the second metal layer within the above range, the first metal layer can have a temperature-responsive active circuit breaking function while also having relatively excellent conductivity, structural strength and mechanical properties.

[0015] In some alternative embodiments, the maximum depth of a single recess is H1, the thickness of the non-recessed region of the temperature response zone matrix in the width direction is H2, the ratio of H1 to H2 is (0.1~0.4):1; or / and, the width of the opening of a single recess is 0.5 mm~1.5 mm.

[0016] In the above technical solution, the ratio of the maximum depth of a single recess to the thickness of the non-recessed area of ​​the temperature response zone substrate in the width direction, and the width of the opening of a single recess are respectively limited within the above range. This enables the first metal layer to have a temperature-responsive active circuit breaking function while also possessing superior conductivity, structural strength, and mechanical properties.

[0017] In a second aspect, embodiments of this application provide a method for preparing a composite current collector as provided in the first aspect embodiment, comprising the following steps: providing a polymer matrix; perforating one side of the temperature-responsive matrix to form a microporous region with multiple pores; injecting a slurry containing an expanding agent into the multiple pores and drying it to remove the solvent in the multiple pores and allow the expanding agent to fill the corresponding pores; hot-pressing the microporous region filled with the expanding agent to seal the expanding agent within the microporous region, and causing at least one side of the temperature-responsive matrix corresponding to the microporous region to be recessed inward to form a recess; forming metal layers on both sides of the polymer matrix, such that the metal layer on the recess side includes a first metal layer located within the recess and a second metal layer located outside the recess, wherein the thickness of the first metal layer is less than the thickness of the second metal layer.

[0018] By following the above process, a composite current collector with advantages such as high circuit breaking reliability and fast response speed can be prepared.

[0019] In some alternative implementations, multiple pores are arranged in an array, and / or the pore density within the micropore region is 5 pores / cm². 2 ~100 pieces / cm 2 The inner diameter of a single pore is 10 μm to 200 μm, and the ratio of the depth of a single pore to the thickness of the substrate in the temperature response zone is (0.1 to 0.5):1.

[0020] In the above technical solution, multiple pores are distributed in an array, and the pore density in the micropore region, the inner diameter of a single pore, and the thickness ratio of a single pore to the temperature response zone matrix are respectively limited within the above range. This allows the expansion agent to be evenly distributed in the temperature response zone matrix, while also enabling the temperature response zone matrix to have both excellent tensile strength and mechanical strength.

[0021] Thirdly, embodiments of this application provide an electrode sheet, including a composite current collector and an active material layer as provided in the first aspect embodiment, wherein the active material layer is present on both sides of the coating region substrate in the thickness direction.

[0022] In the above technical solution, the electrode includes a composite current collector as provided in the first aspect embodiment. Since the composite current collector has the advantages of high circuit breaking reliability and fast response speed when the temperature rises abnormally, the electrode has the advantage of high safety during use.

[0023] Fourthly, embodiments of this application provide a battery including the electrode sheet provided in the third aspect embodiment.

[0024] In the above technical solution, the battery includes the electrode sheet provided in the third aspect embodiment. Since the composite current collector in the electrode sheet has the advantages of high circuit breaking reliability and fast response speed when abnormal temperature rise, the battery has the advantage of high safety during use. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the first composite current collector provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the second composite current collector provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of a polymer matrix provided in an embodiment of this application; Figure 4 Schematic diagrams of the temperature response region matrix at different stages provided in the embodiments of this application; Figure 5 This is a structural schematic diagram showing the relative positions of the linear target and the polymer matrix provided in the embodiments of this application.

[0027] Icons: 10-Composite current collector; 100-Polymer matrix; 110-Coating region matrix; 120-Taper region matrix; 130-Temperature response region matrix; 131-Recess; 132-Expanding agent; 133-Microporous region; 200-Metal layer; 210-First metal layer; 220-Second metal layer; a-Width direction; b-Thickness direction; 20-Linear target; 21-First target; 22-Second target. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, 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 some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of this application, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0033] The following provides a detailed description of a composite current collector with temperature-responsive active circuit breaking function, its preparation method, electrode, and battery provided in this application.

[0034] See Figure 1 and Figure 2(Whereinafter, the polymer matrix 100 is an integral structure, and the dashed lines only indicate the location of the partitions.) In a first aspect, embodiments of this application provide a composite current collector 10 with a temperature-responsive active circuit breaking function, comprising a polymer matrix 100 and a metal layer 200. Along the width direction a of the polymer matrix 100, the polymer matrix 100 includes a coating region matrix 110, a tab region matrix 120, and a temperature-responsive region matrix 130 located between the two. The temperature-responsive region matrix 130 is sealed and filled with an expansion agent 132. In the thickness direction b of the polymer matrix 100, at least one side of the temperature-responsive region matrix 130 has an inwardly recessed portion 131. In the thickness direction b, both sides of the polymer matrix have metal layers 200, and the metal layer 200 located on the side of the recessed portion 131 includes a first metal layer 210 located inside the recessed portion 131 and a second metal layer 220 located outside the recessed portion 131. The thickness of the first metal layer 210 is less than the thickness of the second metal layer 220.

[0035] It should be noted that in a conventional composite current collector 10, the complete polymer matrix 100 is usually divided into two parts: the coating region matrix 110 and the tab region matrix 120. In this application, the complete polymer matrix 100 is divided into three parts, namely, a temperature response region matrix 130 is added between the coating region matrix 110 and the tab region matrix 120.

[0036] It should be noted that in the embodiments of this application, the coating area substrate 110 and the tab area substrate 120 are both set in the form of conventional composite current collector 10. The core point of this application is to add a temperature response area substrate 130 and optimize the structure of the composite current collector 10 in this area based on it.

[0037] It should be noted that the number of recesses 131 on the same side of the temperature response region matrix 130 in the thickness direction b of the polymer matrix is ​​not limited. For example, only one recess 131 can be provided, or two or three recesses 131 can be provided at intervals along the width direction a. (It should be noted that when there are multiple recesses 131, the expansion agent 132 can be set to correspond one-to-one with each of the multiple recesses 131.) In this embodiment, only one recess 131 is provided on the same side as an example. In this application, an expanding agent 132 is sealed and filled inside the temperature-responsive region matrix 130 along the thickness direction b of the polymer matrix 100. At least one side of the temperature-responsive region matrix 130 has an inwardly recessed portion 131. When the composite current collector 10 encounters abnormal temperature rise (e.g., overcharge, short circuit, or high temperature environment), the expanding agent 132 will rapidly expand and apply pressure to the metal layer 200 in the adjacent recess 131 along the thickness direction b, so that the metal layer 200 in this area breaks to achieve circuit breaking. At the same time, the thickness of the first metal layer 210 in the recess 131 is smaller than the thickness of the second metal layer 220, which makes the first metal layer 210 easier to break when subjected to the pressure applied by the expanding agent 132. In addition, the presence of the recess 131 makes the distance between the thinner first metal layer 210 and the expanding agent 132 closer, thereby allowing the first metal layer 210 to be subjected to greater pressure (easier to break) during the expansion of the expanding agent 132. In addition to setting an expansion agent 132 in the polymer matrix 100, the technical solution provided in this application also simultaneously adjusts the thickness and position of the first metal layer 210 corresponding to the expansion agent 132 (specifically, the thickness of the first metal layer 210 is smaller and it is closer to the expansion agent 132). That is, the circuit is broken through multiple mechanisms in synergy, so that the composite current collector 10 has the advantages of high circuit breaking reliability and fast response speed when abnormal temperature rises.

[0038] It should be noted that, in the thickness direction b, when the temperature response zone substrate 130 has a recess 131 on only one side, the metal layer 200 on the opposite side can be set to be the same as the metal layer 200 in the conventional composite current collector 10. For details, please refer to [reference needed]. Figure 1 .

[0039] See Figure 2 and Figure 3 As an example, the temperature response region substrate 130 has recesses 131 on both sides in the thickness direction b.

[0040] In this embodiment, the temperature response region substrate 130 has recesses 131 on both sides in the thickness direction b. Correspondingly, the metal layers 200 on both sides of the polymer substrate 100 each include a first metal layer 210 located in the recesses 131 and a second metal layer 220 located outside the recesses 131. The thickness of the first metal layer 210 is less than the thickness of the second metal layer 220. That is, both sides of the temperature response region substrate 130 have regions with multiple mechanisms for synergistic circuit breaking. When the temperature rises abnormally, both sides of the temperature response region substrate 130 can achieve circuit breaking, which can further improve the reliability and response speed of the composite current collector 10 during abnormal temperature rise.

[0041] It should be noted that when the temperature response zone substrate 130 has recesses 131 on both sides in the thickness direction b, the relative positions of the recesses 131 on both sides are not limited. For example, they can be distributed relatively along the thickness direction b, or they can be distributed in an alternating manner.

[0042] See Figure 3 (Whereinafter, the polymer matrix 100 is a monolithic structure, and the dashed lines only indicate the location of the partitions.) As an example, the temperature response region matrix 130 has recesses 131 on both sides in the thickness direction, and the recesses 131 on both sides of the temperature response region matrix 130 are relatively distributed, that is, the expansion agent 132 is located in the solid region between the two recesses 131.

[0043] In this embodiment, the relatively distributed form has the advantage of a more regular overall structure. At the same time, compared with the staggered distribution form, it can make the distribution of the expanding agent 132 more concentrated, thereby reducing the amount of expanding agent 132 used and the difficulty of packaging the expanding agent 132.

[0044] As an example, the room temperature impact toughness of the first metal layer 210 is less than that of the second metal layer 220.

[0045] In this embodiment, the room temperature impact toughness of the first metal layer 210 is set to be less than that of the second metal layer 220, that is, the first metal layer 210 has poor ductility and high brittleness, so as to realize the triple circuit breaking mechanism of "position + thickness + material", thereby enabling the first metal layer 210 to break more promptly and more easily when subjected to pressure from the expanding agent 132.

[0046] As an example, the resistivity of the first metal layer 210 is higher than that of the second metal layer 220.

[0047] In this embodiment, the resistivity of the first metal layer 210 is set to be higher than that of the second metal layer 220. When the temperature rises abnormally, the temperature of the first metal layer 210 rises faster, and it can transfer the high temperature to the adjacent expansion agent 132 more quickly and achieve rapid circuit breaking through the expansion of the expansion agent 132.

[0048] As an example, the resistivity of the first metal layer 210 to the resistivity of the second metal layer 220 is (2~30):1, for example, but not limited to any one of the ratios 2:1, 5:1, 10:1, 15:1, 20:1, 25:1 and 30:1 or any range between the two.

[0049] In this embodiment, by limiting the ratio of the resistivity of the first metal layer 210 to the resistivity of the second metal layer 220 to the above range, the high temperature can be transferred to the adjacent expansion agent 132 more quickly, and the circuit can be quickly broken by the expansion of the expansion agent 132.

[0050] It should be noted that the materials of the first metal layer 210 and the second metal layer 220 are not limited and can be set according to conventional choices in the field.

[0051] As an example, the material of the first metal layer 210 is selected from at least one of copper alloy, nickel-chromium alloy, titanium and stainless steel, and the material of the second metal layer 220 is selected from at least one of copper, aluminum and silver.

[0052] In this embodiment, there are many ways to combine the first metal layer 210 and the second metal layer 220, which can provide a variety of feasible solutions, thereby facilitating the promotion and application of the technical solutions provided in the embodiments of this application.

[0053] It should be noted that the outline shape of the recess 131 is not limited. For example, it can be V-shaped, U-shaped, semi-circular, trapezoidal, rectangular or square, and can be adapted to actual needs.

[0054] See Figure 2 and Figure 3 As an example, the recess 131 has a V-shaped profile, and in the thickness direction, the thickness of the first metal layer 210 gradually increases from the bottom side of the recess 131 to the opening side.

[0055] In this embodiment, the outline shape of the recess 131 is set to V-shape, and the thickness of the first metal layer 210 is set to gradually increase from the bottom side of the recess 131 to the opening side, that is, the thickness of the first metal layer 210 is in a gradual form. On the one hand, the thickness of the first metal layer 210 near the expanding agent 132 is thinner, which makes the first metal layer 210 in this area easier to break. On the other hand, the thickness of the side where the first metal layer 210 and the second metal layer 220 are connected is thicker, which can increase the stability and reliability of the connection between the two.

[0056] See Figure 3 As an example, the thickness of the first metal layer 210 is D1, the thickness of the second metal layer 220 is D2, and the ratio of D1 to D2 is (0.1~0.95):1, for example, but not limited to any one of the ratios 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, and 0.95:1, or any range between the two.

[0057] In this embodiment, the ratio of the thickness of the first metal layer 210 to the thickness of the second metal layer 220 is limited to the above range, so that the first metal layer 210 has the function of active circuit breaking in response to temperature while also having relatively good conductivity, structural strength and mechanical properties.

[0058] It should be noted that the thickness of the second metal layer 220 in the non-recessed area is not limited and can be set according to the conventional composite current collector 10 in this field. For example, the thickness of the second metal layer 220 is 0.5 μm to 2 μm, such as, but not limited to, any one of the thicknesses of 0.5 μm, 1 μm, 1.5 μm, and 2 μm or any range between two of them.

[0059] See Figure 3 As an example, the maximum depth of a single recess 131 is H1, the thickness of the non-recessed region of the temperature response zone substrate 130 in the width direction a is H2, and the ratio of H1 to H2 is (0.1~0.4):1, for example, but not limited to any one of the ratios 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1 and 0.4:1 or any range between the two.

[0060] It should be noted that "the thickness of the non-recessed region of the temperature response region substrate 130 in the width direction a is H2" means that the temperature response region substrate 130 is divided into a recessed portion 131 and a non-recessed portion 131 (i.e., solid region) adjacent to the recessed portion 131 along the width direction a of the polymer substrate 100. H2 represents the thickness of the adjacent solid region, which is the same as the thickness of the coating region substrate 110 and the electrode region substrate 120.

[0061] It should be noted that the size of H2 is not limited and can be set according to the conventional composite current collector 10. For example, it can be 2 μm to 12 μm, such as, but not limited to, any point value or any range between 2 μm, 4 μm, 6 μm, 8 μm, 10 μm and 12 μm.

[0062] As an example, the width of the opening of a single recess 131 is 0.5 mm to 1.5 mm, for example, but not limited to any one of the following widths or a range between any two: 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm and 1.5 mm.

[0063] In this embodiment, the ratio of the maximum depth of a single recess 131 to the thickness of the non-recessed area of ​​the temperature response region substrate 130 in the width direction a, and the width of the opening of a single recess 131 are respectively limited within the above range. This enables the first metal layer 210 to have a temperature-responsive active circuit breaking function while also possessing superior conductivity, structural strength, and mechanical properties.

[0064] As an example, in the width direction a, the distance between the end of the tab region substrate 120 near the temperature response region substrate 130 and the edge of the recess 131 in the temperature response region substrate 130 is 0.3 mm to 5 mm, for example, but not limited to any one of 0.3 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm and 5 mm or any range between two of the distances.

[0065] In this embodiment, the distance between the end of the tab region substrate 120 near the temperature response region substrate 130 and the edge of the recess 131 in the temperature response region substrate 130 is limited to the above-mentioned range so that the two have a more suitable spacing, thereby facilitating the subsequent precise welding of the tab outside the recess 131.

[0066] As an example, the initial expansion temperature of the expanding agent 132 is 130°C to 200°C, for example, but not limited to any one of 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C and 200°C or a range between any two.

[0067] In this embodiment, the aforementioned temperature range can be well compatible with various common abnormal temperature rise scenarios.

[0068] It should be noted that the composition of the expanding agent 132 is not limited and can be set according to the preset circuit breaking temperature and conventional selection in the field. For example, the embodiment of this application is selected from the thermal expansion microspheres disclosed in patent CN112679791A, wherein the average particle size of the thermal expansion microspheres before thermal expansion is 0.6 μm and the initial expansion temperature is 148℃.

[0069] It should be noted that structural units or functional devices in the composite current collector 10 that are not specifically described or limited can be set according to conventional selection in the art.

[0070] As an example, the polymer matrix 100 is made of at least one of PP (polypropylene), PI (polyimide), and PEN (polyethylene naphthalate).

[0071] In a second aspect, embodiments of this application provide a method for preparing a composite current collector as provided in the first aspect embodiment, comprising the following steps: providing a polymer matrix; perforating one side of the temperature-responsive matrix to form a microporous region with multiple pores; injecting a slurry containing an expanding agent into the multiple pores and drying it to remove the solvent in the multiple pores and allow the expanding agent to fill the corresponding pores; hot-pressing the microporous region filled with the expanding agent to seal the expanding agent within the microporous region, and causing at least one side of the temperature-responsive matrix corresponding to the microporous region to be recessed inward to form a recess; forming metal layers on both sides of the polymer matrix, such that the metal layer on the recess side includes a first metal layer located within the recess and a second metal layer located outside the recess, wherein the thickness of the first metal layer is less than the thickness of the second metal layer.

[0072] In this application, by preparing the composite current collector according to the above process, it is possible to obtain a composite current collector with advantages such as high circuit breaking reliability and fast response speed when abnormal temperature rises.

[0073] As an example, multiple pores are distributed in an array, and / or the pore density within the micropore region is 5 pores / cm². 2 ~100 pieces / cm 2 (For example, but not limited to, a pore density of 5 pores / cm) 2 10 pieces / cm 2 20 pieces / cm2 40 pieces / cm 2 60 pieces / cm 2 80 pieces / cm 2 and 100 / cm 2 The inner diameter of a single pore is 10 μm to 200 μm (e.g., but not limited to any one of the inner diameters of 10 μm, 50 μm, 100 μm, 150 μm, and 200 μm, or any one of the inner diameters of 10 μm, 50 μm, 100 μm, 150 μm, and 200 μm, or / and the ratio of the depth of a single pore to the thickness of the temperature response zone substrate is (0.1 to 0.5):1 (e.g., but not limited to any one of the ratios of 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, and 0.5:1, or any one of the inner diameters of 10 μm, 50 μm, 100 μm, 150 μm, and 200 μm ... and 200 μm, or any one of the inner diameters of 10 μm, 50 μm, 100 μm, 150 μm, and 200 μm, or any one of the inner diameters of 10 μm, 50 μm, 100 μm, and 200 μm, or any one of

[0074] In this embodiment, the multiple pores are distributed in an array, and the pore density in the micropore region, the inner diameter of a single pore, and the thickness ratio of a single pore to the temperature response zone matrix are each limited within the above-mentioned range. This allows the expanding agent to be evenly distributed in the temperature response zone matrix, while also enabling the temperature response zone matrix to have both superior tensile strength and mechanical strength.

[0075] In other possible implementations, the multiple holes may also be arranged in a random distribution.

[0076] As an example, the filling rate of the expansion agent in each hole is 50% to 80%, such as, but not limited to, any point value of 50%, 60%, 70% and 80% or a range of values ​​between any two.

[0077] In this embodiment, the filling rate is limited to the above range. An appropriate amount of filler facilitates the complete sealing of the temperature response zone matrix during the subsequent hot pressing process. At the same time, it also allows the temperature response zone matrix to be filled with a relatively appropriate amount of filler so as to provide a more suitable pressure to achieve circuit breaking during the subsequent expansion process.

[0078] It should be noted that there are no restrictions on the drilling method; for example, laser drilling can be used.

[0079] It should be noted that in the hot pressing process, the outline shape and size of the extrusion head of the hot press are determined by the outline shape and size of the required recess.

[0080] As an example, in the hot pressing step, the hot pressing temperature is lower than the expansion initiation temperature of the expanding agent, and the temperature difference is 10~50℃, for example, but not limited to any one of 10℃, 20℃, 30℃, 40℃ and 50℃ or a range between any two.

[0081] In this embodiment, by limiting the temperature of the hot pressing treatment to the above-mentioned range, the expanding agent can be well sealed within the temperature response zone matrix while better protecting the expanding agent.

[0082] As an example, in the hot pressing step, the pressure is 0.1 MPa to 5 MPa (e.g., but not limited to any one of 0.1 MPa, 0.5 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa and 5 MPa or any range between two), and the holding time is 10 s to 30 s (e.g., but not limited to any one of 10 s, 15 s, 20 s, 25 s and 30 s or any range between two).

[0083] In this embodiment, the pressure and holding time during hot pressing are limited to the above-mentioned ranges, which can effectively seal the expanding agent in the temperature response zone matrix while maintaining the structural integrity of the temperature response zone matrix and the expanding agent.

[0084] It should be noted that there are no restrictions on the method of forming metal layers on both sides of the polymer matrix. It can be carried out according to conventional processes in the field, such as physical vapor deposition, chemical plating, electroplating and cold spraying.

[0085] As an example, magnetron sputtering (a type of physical vapor deposition) is used to form metal layers on both sides of a polymer substrate.

[0086] In this embodiment, magnetron sputtering coating technology is used to form metal layers on both sides of the polymer substrate. By utilizing the shielding effect of the recessed portion on sputtered ions, the thickness of the first metal layer formed in the recessed portion can be made smaller than the thickness of the second metal layer outside the recessed region. There is no need to perform additional thinning or etching treatment on the first metal layer, which has the advantages of simple process and low cost. At the same time, the metal layer formed by magnetron sputtering coating technology also has the advantage of a relatively dense structure.

[0087] It should be noted that in the magnetron sputtering coating process, when the first metal layer and the second metal layer are made of the same material, a linear target of a single material can be used; when the first metal layer and the second metal layer are made of different materials, the linear target of a single material can be replaced with a linear target of two materials. The first target of the linear target is used to correspond to the recessed area, and the second target is used to correspond to the non-recessed area.

[0088] It should be noted that since the formation of a metal layer on the surface of a polymer substrate using magnetron sputtering coating technology is a relatively mature technology, the process steps in this application that are not specifically described or limited in the magnetron sputtering coating process can be carried out in accordance with conventional processes in the field.

[0089] Thirdly, embodiments of this application provide an electrode sheet, including a composite current collector and an active material layer as provided in the first aspect embodiment, wherein the active material layer is present on both sides of the coating region substrate in the thickness direction.

[0090] In this application, the electrode includes the composite current collector provided in the first aspect embodiment. Since the composite current collector has the advantages of high circuit breaking reliability and fast response speed when the temperature rises abnormally, the electrode has the advantage of high safety during use.

[0091] It should be noted that the type of electrode is not limited; it can be a negative electrode or a positive electrode, and the specific type can be adjusted according to actual needs.

[0092] Fourthly, embodiments of this application provide a battery including the electrode sheet provided in the third aspect embodiment.

[0093] In this application, the battery includes the electrode sheet provided in the third aspect embodiment. Since the composite current collector in the electrode sheet has the advantages of high circuit breaking reliability and fast response speed when abnormal temperature rise, the battery has the advantage of high safety during use.

[0094] The technical solution of this application will be further described below with reference to the embodiments.

[0095] Example 1 This application provides a method for preparing a composite current collector, comprising the following steps: A 4.5 μm thick PET film was used as the polymer matrix. A UV laser drilling device (model LHF30PHA) was used to drill holes on one side of the temperature-responsive matrix to form a microporous region. Multiple pores were arranged in an array, with a pore density of 25 pores / cm². 2 The inner diameter of a single pore is 100 μm, and the ratio of the depth of a single pore to the thickness of the temperature-responsive substrate is 0.3:1.

[0096] Thermally expandable microspheres (with an average particle size of 0.6 μm before thermal expansion and an initial expansion temperature of 148℃) were dispersed in ethanol solvent to obtain a slurry with a mass concentration of 15%. The slurry was injected into multiple pores using a micro-sprayer and dried at 60℃ for 30 min to remove the solvent and allow the expanding agent to fill the corresponding pores, with a filling rate of 60%.

[0097] A hot press (with a V-shaped extrusion head) is used to simultaneously hot press both sides of the temperature-responsive substrate and the corresponding micropore region. The hot pressing temperature is 120℃, the pressure is 1.5 MPa, and the holding time is 10 s. This seals the expanding agent within the micropore region and softens the temperature-responsive substrate within this region, extruding it to form a recess. The two recesses on either side are relatively distributed, with a V-shaped outline. The ratio of the maximum depth of a single recess to the thickness of the non-recessed area of ​​the temperature-responsive substrate in the width direction is 0.3:1, and the width of the opening of a single recess is 0.8 mm. Schematic diagrams of the various stages of the temperature-responsive substrate before magnetron sputtering coating can be found in [reference needed]. Figure 4 According to the arrow square steel, the first figure is a structural schematic diagram of the untreated temperature response zone substrate 130, the second figure is a structural schematic diagram of the temperature response zone substrate 130 after the formation of the microporous region 133, the third figure is a structural schematic diagram of the temperature response zone substrate 130 filled with the expanding agent 132 after solvent removal, and the fourth figure is a structural schematic diagram of the temperature response zone substrate 130 after the expanding agent 132 is sealed and the recess 131 is formed simultaneously.

[0098] The polymer substrate with the recessed portion is transferred to a magnetron sputtering coating apparatus for magnetron sputtering coating. The target is a linear target with two materials, and the relative positions of the linear target 20 and the polymer substrate 100 are shown in [reference needed]. Figure 5 The first target material 21 (made of Cu) 70 Ni 30 The first target (purity 99.9%) corresponds to the recessed area 131, and the second target 22 (pure copper) corresponds to the non-recessed area. The vacuum degree in the coating chamber is 5×10⁻⁶. -4 The working gas was Ar, the working pressure was 0.3 Pa, the sputtering power was 400 W, and the deposition time was 25 min, so as to form metal layers on both sides of the polymer matrix. Each metal layer includes a first metal layer (made of Cu) located within the recess. 70 Ni 30 The material is Cu (with a thickness of 1 μm) at the bottom of the recess and a thickness of 0.9 μm at the opening of the recess.

[0099] Example 2 This application provides a method for preparing a composite current collector, which differs from Example 1 only in that the target material is a linear target material of a single material (pure copper).

[0100] Comparative Example 1 This application provides a comparative example of a method for preparing a composite current collector, comprising the following steps: A 4.5 μm thick PET film was used as the polymer matrix. A UV laser drilling device (model LHF30PHA) was used to drill holes on one side of the temperature-responsive matrix to form a microporous region. Multiple pores were arranged in an array, with a pore density of 25 pores / cm². 2 The inner diameter of a single pore is 100 μm, and the ratio of the depth of a single pore to the thickness of the temperature-responsive substrate is 0.3:1.

[0101] Thermally expandable microspheres (with an average particle size of 0.6 μm before thermal expansion and an initial expansion temperature of 148℃) were dispersed in ethanol solvent to obtain a slurry with a mass concentration of 15%. The slurry was injected into multiple pores using a micro-sprayer and dried at 60℃ for 30 min to remove the solvent and allow the expanding agent to fill the corresponding pores, with a filling rate of 60%.

[0102] A flatbed hot press is used to simultaneously hot press both sides of the entire polymer matrix. The hot pressing temperature is 120℃, the pressure is 0.8 MPa, and the holding time is 10 s, so as to seal the expansion agent in the microporous area, and the two sides of the polymer matrix remain planar after hot pressing.

[0103] The polymer substrate is transferred to a magnetron sputtering coating apparatus for magnetron sputtering coating. The target is a linear target of a single material (pure copper), and the vacuum level in the coating chamber is 5 × 10⁻⁶. -4 The working gas was Ar, the working pressure was 0.3 Pa, the sputtering power was 400 W, and the deposition time was 25 min, so as to form metal layers on both sides of the polymer matrix. The two metal layers were made of Cu and had a thickness of 1 μm.

[0104] Comparative Example 2 This application provides a comparative example of a method for preparing a composite current collector, comprising the following steps: A 4.5 μm thick PET film was used as the polymer substrate. The polymer substrate was transferred to a magnetron sputtering coating apparatus for magnetron sputtering coating. The target material was a linear target of a single material (pure copper), and the vacuum degree in the coating chamber was 5 × 10⁻⁶. -4 The working gas was Ar, the working pressure was 0.3 Pa, the sputtering power was 400 W, and the deposition time was 25 min, so as to form metal layers on both sides of the polymer matrix. The two metal layers were made of Cu and had a thickness of 1 μm.

[0105] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A composite current collector with temperature-responsive active circuit breaking function, characterized in that, include: A polymer matrix, along the width direction of the polymer matrix, includes a coating region matrix, a tab region matrix, and a temperature-responsive region matrix located between the two; the temperature-responsive region matrix is ​​filled with an expanding agent, and in the thickness direction of the polymer matrix, at least one side of the temperature-responsive region matrix has an inwardly recessed portion; The metal layer has metal layers on both sides of the polymer matrix in the thickness direction, and the metal layer on the recess side includes a first metal layer located inside the recess and a second metal layer located outside the recess, wherein the thickness of the first metal layer is less than the thickness of the second metal layer.

2. The composite current collector according to claim 1, characterized in that, The temperature response region substrate has the recesses on both sides in the thickness direction.

3. The composite current collector according to claim 1 or 2, characterized in that, The room temperature impact toughness of the first metal layer is less than that of the second metal layer. Or / and, the resistivity of the first metal layer is higher than that of the second metal layer.

4. The composite current collector according to claim 3, characterized in that, The material of the first metal layer is selected from at least one of copper alloy, nickel-chromium alloy, titanium and stainless steel, and the material of the second metal layer is selected from at least one of copper, aluminum and silver.

5. The composite current collector according to claim 1 or 2, characterized in that, The recess has a V-shaped profile, and in the thickness direction, the thickness of the first metal layer gradually increases from the bottom side of the recess to the opening side. Or / and, the thickness of the first metal layer is D1, the thickness of the second metal layer is D2, and the ratio of D1 to D2 is (0.1~0.95):

1.

6. The composite current collector according to claim 1 or 2, characterized in that, The maximum depth of a single recess is H1, the thickness of the non-recessed region of the temperature response zone matrix in the width direction is H2, and the ratio of H1 to H2 is (0.1~0.4):1; Or / and, the width of the opening at a single recess is 0.5 mm to 1.5 mm.

7. A method for preparing a composite current collector as described in any one of claims 1 to 6, characterized in that, Includes the following steps: The polymer matrix is ​​provided, and a perforation process is performed on one side of the temperature response region matrix to form a microporous region with multiple pores; The slurry containing the expanding agent is injected into a plurality of the pores and dried to remove the solvent from the plurality of the pores and to allow the expanding agent to fill the corresponding pores. The microporous region filled with the expanding agent is subjected to hot pressing treatment to seal the expanding agent in the microporous region, and to cause at least one side of the temperature response region matrix corresponding to the microporous region to be recessed inward to form the recessed portion; The metal layers are formed on both sides of the polymer matrix, such that the metal layer on the recess side includes a first metal layer located inside the recess and a second metal layer located outside the recess, wherein the thickness of the first metal layer is less than the thickness of the second metal layer.

8. The method for preparing the composite current collector according to claim 7, characterized in that, The multiple pores are arranged in an array, and / or the pore density within the micropore region is 5 pores / cm². 2 ~100 pieces / cm 2 The inner diameter of a single hole is 10 μm to 200 μm, and the ratio of the depth of a single hole to the thickness of the temperature response zone substrate is (0.1 to 0.5):

1.

9. An electrode sheet, characterized in that, include: Composite current collector as described in any one of claims 1 to 6; An active material layer is provided on both sides of the coating region substrate in the thickness direction.

10. A battery, characterized in that, The battery includes the electrode as described in claim 9.

Images