Composite current collector, electrode tab, and electrochemical device

Abstract

The application discloses a composite current collector, an electrode pole piece and an electrochemical device. The composite current collector comprises a base, a first connecting layer and a first conductive layer. The first connecting layer is used for bonding the first conductive layer to a first surface of the base. A first passivation layer is formed on a surface of the first conductive layer close to the first connecting layer. The composite current collector can avoid the electrolyte from contacting the first conductive layer when entering from the side opposite to the first connecting layer, so as to prevent the first conductive layer from being corroded and damaged by the electrolyte, and improve the stability of the current collector.

Description

[0001] Cross-reference to related applications This application is a divisional application of application number 202080005428.9, filed on September 23, 2020, entitled "Composite current collector, electrode sheet and electrochemical device". Technical Field

[0002] This application relates to a composite current collector, electrode plates, and an electrochemical device. Background Technology

[0003] Electrochemical devices, capable of charging and discharging, are widely used in consumer products, digital products, power products, medical devices, and security applications. The current collector, serving as the carrier of the active material in an electrochemical device, is a crucial component and is closely related to the device's energy density. Current current collector manufacturing processes typically involve depositing a metal-polymer film onto a low-density polymer film surface using metal physical vapor deposition. To achieve superior conductivity, a thicker metal layer needs to be deposited on the polymer film. However, increasing the current collector thickness reduces the energy density of the electrochemical device, and current collectors produced using this method have poor resistance to electrolyte corrosion, making the metal layer prone to detachment and failure during long-term operation. Summary of the Invention

[0004] This application aims to at least solve one of the technical problems existing in the prior art. To this end, one aspect of this application is to propose a composite current collector, which, by forming a passivation layer on the side of the conductive layer near the connecting layer, can prevent the electrolyte from contacting the conductive layer when entering from the side opposite to the connecting layer, thus avoiding corrosion and damage to the conductive layer by the electrolyte, thereby improving the stability of the current collector.

[0005] This application provides a composite current collector, including a substrate, a first connecting layer, and a first conductive layer. The first connecting layer is used to bond the first conductive layer to a first surface of the substrate. A first passivation layer is formed on the surface of the first conductive layer near the first connecting layer.

[0006] In some embodiments, the composite current collector further includes a second connecting layer and a second conductive layer, wherein the second connecting layer is used to bond the second conductive layer to a second surface of the substrate, and a second passivation layer is formed on the surface of the second conductive layer near the second connecting layer.

[0007] In some embodiments, the thickness of the substrate is 2μm-36μm, the thickness of the first connecting layer is 0.2μm-2μm, the thickness of the first conductive layer is 100 nm-5000nm, and the thickness of the first passivation layer is 5 nm-200nm.

[0008] In some embodiments, the substrate is selected from at least one of polyethylene film, polypropylene film, polyethylene terephthalate film, polyethylene terephthalate film, poly(p-phenylene terephthalamide) film, polyimide film, polycarbonate film, polyetheretherketone film, polyoxymethylene film, polyphenylene sulfide film, poly(p-phenylene ether) film, polyvinyl chloride film, polyamide film, and polytetrafluoroethylene film.

[0009] In some embodiments, the first connecting layer is selected from at least one of polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, modified polyolefin resin, silicone resin, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and polyamide.

[0010] In some embodiments, the first passivation layer is selected from at least one of an alumina layer, a titanium oxide layer, a zirconium oxide layer, an aluminum nitride layer, a titanium nitride layer, a titanium carbide layer, a zirconium carbide layer, a silicon dioxide layer, a silicon nitride layer, a silicon carbide layer, and an aluminum chromate layer.

[0011] In some embodiments, the first conductive layer is selected from at least one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum, and tungsten.

[0012] In some embodiments, a groove pattern is provided on the first surface of the substrate, and the connecting layer further fills the groove pattern.

[0013] In some embodiments, the groove pattern consists of one or more hole-like structures.

[0014] In some embodiments, at least one of the porous structures penetrates the substrate, or at least one of the porous structures does not penetrate the substrate.

[0015] Another aspect of this application involves providing an electrode sheet comprising a composite current collector and an active material layer. The composite current collector includes a substrate, a first connecting layer, and a first conductive layer. The first connecting layer is used to bond the first conductive layer to a first surface of the substrate. A first passivation layer is formed on the surface of the first conductive layer near the first connecting layer. The active material layer is disposed on the surface of the first conductive layer of the composite current collector facing away from the substrate.

[0016] Another aspect of this application discloses an electrochemical device including an electrode. The electrode includes a composite current collector and an active material layer. The composite current collector includes a substrate, a first connecting layer, and a first conductive layer. The first connecting layer is used to bond the first conductive layer to a first surface of the substrate; a first passivation layer is formed on the surface of the first conductive layer near the first connecting layer. The active material layer is disposed on the surface of the first conductive layer of the composite current collector facing away from the substrate.

[0017] According to the composite current collector of this application embodiment, by forming a passivation layer on the side of the conductive layer near the connecting layer, the electrolyte can be prevented from contacting the conductive layer when entering from the side opposite to the connecting layer and the conductive layer, thus avoiding corrosion and damage to the conductive layer by the electrolyte, thereby improving the stability of the current collector. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A schematic diagram of the structure of a composite current collector according to an embodiment of this application is shown; Figure 2 A schematic diagram of the structure of a composite current collector according to another embodiment of this application is shown; Figure 3 A schematic diagram of a structure in which a groove pattern is formed on the surface of a substrate according to an embodiment of the present application is shown; Explanation of key component symbols: The substrate 10, the first surface 11, the second surface 12, the first connecting layer 20, the first conductive layer 30, the first passivation layer 40, the second connecting layer 50, the second conductive layer 60, the second passivation layer 70, the groove pattern 80, and the hole structure 81. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0020] The following is for reference. Figures 1-3 The composite current collector 100 according to an embodiment of this application is described in detail.

[0021] like Figure 1As shown, the composite current collector 100 according to an embodiment of this application includes a substrate 10, a first connecting layer 20, a first conductive layer 30, and a first passivation layer 40. The first connecting layer 20 is located between the substrate 10 and the first conductive layer 30, and the first passivation layer 40 is formed on the surface of the first conductive layer 30 near the surface of the first connecting layer 20. One surface of the first connecting layer 20 is bonded to the first surface 11 of the substrate 10, and the other surface of the first connecting layer 20 is bonded to the first passivation layer 40, thereby enabling the first connecting layer 20 to bond the first conductive layer 30 to the first surface 11 of the substrate 10.

[0022] For example, the first passivation layer 40 can be tightly bonded to the surface of the first conductive layer 30 by chemical reaction or vapor deposition.

[0023] like Figure 2 As shown, the composite current collector 100 further includes a second connecting layer 50, a second conductive layer 60, and a second passivation layer 70. The second connecting layer 50 is located between the substrate 10 and the second conductive layer 60, and the second passivation layer 70 is formed on the surface of the second conductive layer 60 near the surface of the second connecting layer 50. One surface of the second connecting layer 50 is bonded to the second surface 11 of the substrate 10, and the other surface of the second connecting layer 50 is bonded to the second passivation layer 70, thereby enabling the second connecting layer 50 to bond the second conductive layer 60 to the second surface 12 of the substrate 10.

[0024] For example, the second passivation layer 70 can be tightly bonded to the surface of the second conductive layer 60 by chemical reaction or vapor deposition.

[0025] In some embodiments, the first conductive layer 30 and the second conductive layer 60 can be fabricated using a physical vapor deposition (PVD) process, which can be selected from magnetron sputtering, crucible boat evaporation deposition, and electron beam evaporation deposition. The first conductive layer 30 and the second conductive layer 60 can be processed by electron beam evaporation, DC magnetron sputtering, radio frequency magnetron sputtering, surface oxidation, chemical deposition, spraying, etc., to form a first passivation layer 40 and a second passivation layer 70 on their surfaces, respectively. The first passivation layer 40 can prevent electrolyte from contacting the first conductive layer 30 when entering from the side opposite to the first connecting layer 20, thus preventing corrosion and damage to the first conductive layer 30. The second passivation layer 70 can prevent electrolyte from contacting the second conductive layer 60 when entering from the side opposite to the second connecting layer 50, thus preventing corrosion and damage to the second conductive layer 60, thereby improving the stability of the composite current collector 100.

[0026] In some embodiments, the substrate 10 may be selected from at least one of polyethylene film, polypropylene film, polyethylene terephthalate film, polyethylene terephthalate film, poly(p-phenylene terephthalamide) film, polyimide film, polycarbonate film, polyetheretherketone film, polyoxymethylene film, polyphenylene sulfide film, poly(p-phenylene ether) film, polyvinyl chloride film, polyamide film, and polytetrafluoroethylene film. The thickness of the substrate 10 may be 2 μm to 36 μm.

[0027] In some embodiments, the materials of the first connecting layer 20 and the second connecting layer 50 may be selected from at least one of polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, modified polyolefin resin, silicone resin, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and polyamide. The thickness of both the first connecting layer 20 and the second connecting layer 50 may be 0.2 μm to 2 μm.

[0028] In some embodiments, the materials of the first conductive layer 30 and the second conductive layer 60 may be selected from at least one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum, and tungsten. The thickness of both the first conductive layer 30 and the second conductive layer 60 may be 100 nm to 5000 nm.

[0029] In some embodiments, the first passivation layer 40 and the second passivation layer 70 may be selected from at least one of an alumina layer, a titanium oxide layer, a zirconium oxide layer, an aluminum nitride layer, a titanium nitride layer, a titanium carbide layer, a zirconium carbide layer, a silicon dioxide layer, a silicon nitride layer, a silicon carbide layer, and an aluminochromate layer. The thickness of both the first passivation layer 40 and the second passivation layer 70 may be 5 nm to 200 nm. In other embodiments, the first passivation layer 40 may also be formed by coating a passivation liquid onto the surface of the first conductive layer 30 near the first connection layer 20, and the second passivation layer 70 may also be formed by coating a passivation liquid onto the surface of the second conductive layer 60 near the second connection layer 50. The passivation liquid can refer to a solution that can make a metal surface passive; the passivation liquid can form a surface state on the metal surface that can prevent normal metal reactions, thereby improving its corrosion resistance.

[0030] The composite current collector 100 of this application embodiment forms a passivation layer on the side of the conductive layer near the connecting layer, which can prevent the electrolyte from contacting the conductive layer when it enters from the side opposite to the connecting layer and the conductive layer, thus avoiding corrosion and damage to the conductive layer by the electrolyte and improving the stability of the current collector.

[0031] like Figure 3As shown, the first surface 11 of the substrate 10 is provided with a groove pattern 80, and the first connecting layer 20 can also fill the groove pattern 80, thereby improving the adhesion between the first connecting layer 20 and the substrate 10, making the first conductive layer 30 less likely to fall off the substrate 10, and further improving the stability of the current collector.

[0032] In some embodiments, the first surface 11 of the substrate 10 can be patterned by drilling, engraving, or other methods to form a groove pattern 80. For example, the groove pattern 80 can be formed on the first surface 11 by laser drilling, nuclear track etching, chemical etching, photochemical etching, or other methods.

[0033] In some embodiments, the groove pattern 80 may be composed of one or more perforated structures 81, which may be configured to penetrate the substrate 10 or not, depending on actual needs. For example, all of the perforated structures 81 may penetrate the substrate 10, none of the perforated structures 81 may penetrate the substrate 10, or some of the perforated structures 81 may penetrate the substrate 10 while others may not.

[0034] In some embodiments, the shape of the pore structure 81 can be set according to actual needs, such as... Figure 3 The hole structure 81 shown is a circular hole. The hole structure 81 can also be a triangular hole, a quadrilateral hole, a polygonal hole, an irregularly shaped hole, etc.

[0035] In some embodiments, the second surface 12 of the substrate 10 may also be provided with a groove pattern 80, and the second connecting layer 50 fills the groove pattern 80, thereby improving the adhesion between the second connecting layer 50 and the substrate 10, making it less likely for the second conductive layer 60 to fall off from the substrate 10.

[0036] In addition, this application also discloses an electrode sheet, which includes the composite current collector 100 of any of the above-mentioned cases.

[0037] In some embodiments, an active material layer is disposed on the surface of the first conductive layer 30 away from the first connecting layer 20, and the same active material layer is disposed on the surface of the second conductive layer 60 away from the second connecting layer 50. If the composite current collector 100 is a cathode current collector, then the active material layer is a cathode active material coating. If the composite current collector 100 is an anode current collector, then the active material layer is an anode active material coating.

[0038] Furthermore, this application also discloses an electrochemical device comprising electrode plates as described above. The electrochemical device can be a lithium-ion battery, a lithium polymer battery, etc.

[0039] The comparative examples 1, 2 and 3 described below are all composite current collectors without a passivation layer.

[0040] Comparative Example 1 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, after the crucible boat temperature is adjusted to 1200-1500℃, aluminum plating begins. Aluminum plating is stopped once the aluminum content reaches 200nm. A 12μm thick polyethylene terephthalate film is corona treated, and a mixture of bisphenol A epoxy resin and amine curing agent is coated onto its surface. Within the open time of the coating, the previously treated polyethylene terephthalate film and the surface of the polyimide film with the aluminum plating layer are hot-pressed together (hot-pressing temperature is 85℃, pressure is 0.7MPa) to obtain the first comparative composite current collector.

[0041] Comparative Example 2 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, after the crucible boat temperature is adjusted to 1200-1500℃, aluminum plating begins. Aluminum plating is stopped once the aluminum thickness reaches 500nm. A 12μm thick polyethylene terephthalate film is corona treated, and a mixture of bisphenol A epoxy resin and amine curing agent is coated onto its surface. Within the open time of the coating, the previously treated polyethylene terephthalate film and the surface of the polyimide film with the aluminum plating layer are hot-pressed together (hot-pressing temperature is 85℃, pressure is 0.7MPa) to obtain the second comparative composite current collector.

[0042] Comparative Example 3 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, after the crucible boat temperature is adjusted to 1200-1500℃, aluminum plating begins. Aluminum plating is stopped once the aluminum thickness reaches 500nm. A 12μm thick polyethylene terephthalate film is corona treated, and a one-component polyurethane adhesive is coated onto its surface. Within the open time of the coating, the previously treated polyethylene terephthalate film and the aluminum-coated surface of the polyimide film are hot-pressed together (hot-pressing temperature 85℃, pressure 0.7MPa) to obtain the third comparative composite current collector.

[0043] The specific embodiments 1 to 6 described below are composite current collectors containing a passivation layer as described in the embodiments of the present invention.

[0044] Example 1 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, after the crucible boat temperature is adjusted to 1200-1500℃, aluminum plating begins. Once the aluminum thickness reaches 200nm, aluminum plating is stopped, and a 5nm thick Al2O3 passivation layer is sputtered onto the aluminum surface for later use. A 12μm thick polyethylene terephthalate film is corona treated, and a mixture of bisphenol A epoxy resin and amine curing agent is coated onto its surface. Within the open time of the coating, the previously treated polyethylene terephthalate film and the passivated aluminum plating layer on the polyimide film are hot-pressed together (hot-pressing temperature 85℃, pressure 0.7MPa) to obtain the first composite current collector.

[0045] Example 2 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, after the crucible boat temperature is adjusted to 1200-1500℃, aluminum plating begins. Once the aluminum thickness reaches 500nm, aluminum plating is stopped, and a 10nm thick Al2O3 passivation layer is sputtered onto the aluminum surface for later use. A 12μm thick polyethylene terephthalate (PET) film is corona treated, and a mixture of bisphenol A epoxy resin and amine curing agent is coated onto its surface. Within the open time of the coating, the previously treated PET film and the passivated aluminum plating layer on the polyimide film are hot-pressed together (hot-pressing temperature 85℃, pressure 0.7MPa) to obtain the second composite current collector.

[0046] Example 3 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, after the crucible boat temperature is adjusted to 1200-1500℃, aluminum plating begins. Once the aluminum thickness reaches 500nm, plating is stopped, and a 20nm thick Al2O3 passivation layer is sputtered onto the aluminum surface for later use. A 12μm thick polyethylene terephthalate (PET) film is corona-treated, and a mixture of bisphenol A epoxy resin and an amine curing agent is coated onto its surface. Within the open time of the coating, the previously treated PET film and the passivated aluminum plating layer on the polyimide film are hot-pressed together (hot-pressing temperature: 85℃, pressure: 0.7MPa) to obtain the third composite current collector.

[0047] Example 4 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, after the crucible boat temperature is adjusted to 1200-1500℃, aluminum plating begins. Once the aluminum thickness reaches 500nm, plating is stopped, and a 20nm thick Al2O3 passivation layer is sputtered onto the aluminum surface for later use. A 12μm thick polyethylene terephthalate (PET) film is corona-treated, and a one-component polyurethane adhesive is coated onto its surface. Within the open time of the coating, the previously treated PET film and the passivated aluminum plating layer on the polyimide film are hot-pressed together (hot-pressing temperature 85℃, pressure 0.7MPa) to obtain the fourth composite current collector.

[0048] Example 5 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, after the crucible boat temperature is adjusted to 1200-1500℃, aluminum plating begins. Once the aluminum thickness reaches 500nm, aluminum plating is stopped, and a 20nm thick TiO2 passivation layer is sputtered onto the aluminum layer surface for later use. A 12μm thick polyethylene terephthalate (PET) film is corona treated, and a one-component polyurethane adhesive is coated onto its surface. Within the open time of the coating, the previously treated PET film and the passivated aluminum plating layer on the polyimide film are hot-pressed together (hot-pressing temperature 85℃, pressure 0.7MPa) to obtain the fifth composite current collector.

[0049] Example 6 A 50μm thick polyimide film was placed in the vacuum chamber of a crucible-boat type vacuum evaporation aluminum plating machine. The vacuum chamber was sealed, and the air pressure of the vacuum aluminum plating machine was evacuated to 10. -3 Pa, once the crucible boat temperature is adjusted to 1200-1500℃, begin aluminum plating. Stop plating once the aluminum thickness reaches 500nm, then coat with a Cr-containing coating. 3+ The coating solution forms an aluminum chromate passivation layer of approximately 200 nm thickness for later use. A 12 μm thick polyethylene terephthalate film is subjected to corona treatment, and a one-component polyurethane adhesive is coated on its surface. Within the open time of the coating, the previously treated polyethylene terephthalate film and the passivated surface of the aluminum-plated layer on the polyimide film are hot-pressed together (hot-pressing temperature is 85℃, pressure is 0.7 MPa) to obtain the sixth composite current collector.

[0050] In some embodiments, immersion experiments were conducted on the composite current collectors obtained in Examples 1-6 and Comparative Examples 1-3. The procedure was as follows: each composite current collector was cut into a current collector strip with a length of 5 cm and a width of 2 cm, immersed in electrolyte, and sealed with aluminum-plastic film to remove external environmental interference. Finally, it was placed in a constant temperature drying oven at 85°C for 72 hours and then removed to observe the appearance of each composite current collector. Table 1 below summarizes the observation results of the composite current collectors in Examples 1-6 compared with Comparative Examples 1-3.

[0051] As shown in Table 1 above, the electrolyte tolerance of the composite current collectors in Examples 1-6 is significantly better than that in Comparative Examples 1-3. This indicates that setting a passivation layer on the inner surface of the conductive layer can prevent the electrolyte from contacting the conductive layer when it enters from the surface opposite to the connecting layer and the conductive layer, thus avoiding corrosion and damage to the conductive layer by the electrolyte, thereby improving the stability of the composite current collector.

[0052] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, 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 of this application. In the description of this application, "a plurality of" means two or more.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0054] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application.

Claims

1. A composite current collector, characterized in that, It includes a substrate, a first interconnect layer, and a first conductive layer. The first connecting layer is used to bond the first conductive layer to the first surface of the substrate, the first surface of the substrate is provided with a groove pattern, and the first connecting layer is also filled in the groove pattern; A first passivation layer is formed on the surface of the first conductive layer near the first connecting layer, and the thickness of the first conductive layer is 100nm-5000nm; The substrate is selected from at least one of polyethylene film, polypropylene film, polyethylene terephthalate film, polyethylene terephthalate film, poly(p-phenylene terephthalamide) film, polyimide film, polycarbonate film, polyetheretherketone film, polyoxymethylene film, polyphenylene sulfide film, poly(p-phenylene ether) film, polyvinyl chloride film, polyamide film, and polytetrafluoroethylene film.

2. The composite current collector as described in claim 1, characterized in that, The composite current collector further includes a second connecting layer and a second conductive layer. The second connecting layer is used to bond the second conductive layer to the second surface of the substrate. A second passivation layer is formed on the surface of the second conductive layer near the second connecting layer.

3. The composite current collector as described in claim 1, characterized in that, The thickness of the substrate is 2μm-36μm, the thickness of the first connecting layer is 0.2μm-2μm, and the thickness of the first passivation layer is 5nm-200nm.

4. The composite current collector as described in claim 1, characterized in that, The first connecting layer is selected from at least one of polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, modified polyolefin resin, silicone resin, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and polyamide.

5. The composite current collector as described in claim 1, characterized in that, The first passivation layer is selected from at least one of the following: aluminum oxide layer, titanium oxide layer, zirconium oxide layer, aluminum nitride layer, titanium nitride layer, titanium carbide layer, zirconium carbide layer, silicon dioxide layer, silicon nitride layer, silicon carbide layer, and aluminum chromate layer.

6. The composite current collector as described in claim 1, characterized in that, The first conductive layer is selected from at least one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum, and tungsten.

7. The composite current collector as described in claim 1, characterized in that, The groove pattern consists of one or more hole-like structures.

8. The composite current collector as described in claim 7, characterized in that, At least one of the pore structures penetrates the substrate, or at least one of the pore structures does not penetrate the substrate.

9. An electrode sheet, characterized in that, include: The composite current collector according to any one of claims 1-8; and An active material layer is disposed on the surface of the first conductive layer of the composite current collector that is away from the substrate.

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

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