A prelithiation functional current collector, a preparation method thereof, a negative electrode sheet, and a battery

Abstract

The application discloses a pre-lithiation functional current collector and a preparation method thereof, a negative plate and a battery. The pre-lithiation functional current collector comprises: a polymer support layer serving as a support base at the center of the current collector; a structured copper layer arranged on at least one side of the polymer support layer, wherein the surface of the structured copper layer is a three-dimensional micro-nano structure serving as a lithium deposition anchor point; a lithiumophilic interface layer covering the surface of the structured copper layer, wherein the lithiumophilic interface layer is composed of a lithiumophilic material; and a metal lithium filling layer compressed on the structured copper layer with the lithiumophilic interface layer on the surface, and the metal lithium in the metal lithium filling layer is embedded and filled in the three-dimensional micro-nano structure of the structured copper layer through pressure. The pre-lithiation functional current collector can effectively inhibit lithium dendrites and adapt to the volume change of lithium deposition.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a pre-lithiated functional current collector and its preparation method, a negative electrode, and a battery. Background Technology

[0002] In the field of lithium metal batteries, the current collector, as the carrier for lithium deposition and the conductive framework inside the battery, directly determines the electrochemical performance, safety performance, and cost control of the battery through its structure and manufacturing process. Currently, the mainstream lithium metal carriers and related processes in the industry still have many defects and shortcomings, making it difficult to meet the industrialization requirements of high performance, lightweight, and low cost. Among them, the most commonly used traditional lithium metal carrier solution is the combination of electrolytic copper foil and electrodeposited lithium. This solution relies on planar electrolytic copper foil as a substrate. Since the surface of the planar copper foil has no effective lithium deposition anchor points, it cannot induce uniform nucleation and deposition of lithium ions, and lithium dendrites are easily generated. The growth of lithium dendrites not only leads to a sharp decline in battery cycle stability, but may also puncture the separator and cause short circuits, posing serious safety hazards. At the same time, the electrochemical lithium deposition process is complicated and the reaction conditions are harsh, which not only increases production costs, but also has problems such as low deposition efficiency and poor product consistency, making it difficult to adapt to the needs of large-scale production.

[0003] To address the shortcomings of traditional electrolytic copper foil, composite copper foil solutions have gradually emerged, with the polymer-copper-polymer structure being the most typical. This type of composite copper foil, thanks to the characteristics of its intermediate polymer support layer, possesses significant advantages such as lightweight, low cost, and high flexibility. Furthermore, the insulating polymer layer can melt during a battery short circuit, providing a degree of fuse protection, making it a promising candidate for applications in power and consumer batteries. However, existing composite copper foils still have significant limitations. Their copper layer surface remains a two-dimensional flat structure, and copper itself has poor lithium affinity, failing to fundamentally solve the critical issues of uneven lithium-ion deposition and volume expansion during lithium deposition. This leads to problems such as lithium dendrite growth, poor interfacial contact, and poor cycle stability when used directly as a lithium metal carrier, making it difficult for battery performance to meet expectations.

[0004] In addition, a combination of three-dimensional porous current collectors and lithium has emerged in the industry. This approach, by constructing a three-dimensional porous structure, can effectively increase the specific surface area and provide sufficient space for lithium deposition, thereby improving lithium deposition behavior and inhibiting lithium dendrite growth, offering certain advantages in enhancing battery cycle stability. However, this type of approach also has significant limitations. Three-dimensional porous current collectors are typically prepared using complex processes such as metal powder sintering and template methods. These processes are not only cumbersome and costly, but the porous structure itself increases the weight of the current collector, leading to a decrease in battery energy density. This makes it difficult to simultaneously meet the dual requirements of energy density and electrochemical performance, limiting its industrial application. In summary, all existing lithium metal carrier solutions have unavoidable drawbacks. Developing a pre-lithiation functional current collector solution that can balance performance, cost, safety, and large-scale production has become an urgent need for the industry. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing lithium metal carrier solutions, such as lithium dendrite growth, volume expansion, poor performance, complex processes, or high costs. It provides a pre-lithiation functional current collector and its preparation method that integrates lightweight, high safety, and high performance, has a simple and controllable process, is suitable for large-scale production, and can effectively suppress lithium dendrites and adapt to changes in lithium deposition volume.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: The first aspect of this application provides a pre-lithiated functional current collector, comprising: The polymer support layer serves as the supporting foundation for the current collector center; A structured copper layer is disposed on at least one side of the polymer support layer, wherein the surface of the structured copper layer is a three-dimensional micro / nano structure serving as lithium deposition anchor points; A lithiophilic interface layer is applied to the surface of the structured copper layer, and the lithiophilic interface layer is composed of a lithiophilic material. A lithium metal filling layer is laminated onto a structured copper layer with a lithium-philic interface layer on its surface, and the lithium metal in the lithium metal filling layer is embedded and filled into the three-dimensional micro / nano structure of the structured copper layer by pressure.

[0007] To optimize the above technical solution, the specific limitations also include: The structured copper layer consists of two different magnetron layers: the inner magnetron layer is a dense copper layer used to prevent the electrolyte from contacting the polymer support layer, and the outer magnetron layer is a loose copper layer used for lithium metal embedding and filling. The surface of the outer magnetron layer has a three-dimensional micro-nano structure.

[0008] The three-dimensional micro / nano structure is a nanocone array, nanowire cluster, porous network structure, or micron-sized pits; the lithiophilic material is selected from one or more of zinc oxide, copper nitride, silver nanoparticles, and gold nanoparticles.

[0009] The magnetron thickness of the inner and outer magnetron layers is 20-30 nm, respectively; the thickness of the lithiophilic interface layer is 10-30 nm; and the thickness of the lithium metal filling layer is 10-40 μm.

[0010] A second aspect of this application provides a method for preparing a pre-lithiated functional current collector, comprising the following steps: S1: A planar copper layer is prepared on the surface of a polymer support layer by magnetron sputtering; S2: The flat copper layer is surface treated to construct a three-dimensional micro-nano structure, thereby obtaining a structured composite copper foil; S3: Deposit a thin film of lithium-philic material on the surface of the structured composite copper foil; S4: Under the protection of an inert atmosphere, a lithium metal strip is stacked and pressurized with a structured composite copper foil on which a lithium-loving material film is deposited. Under pressure, the lithium metal flows plastically and fills the three-dimensional micro-nano structure of the structured composite copper foil to form an integrated functional current collector.

[0011] To optimize the above technical solution, the specific measures also include: Step S1 involves preparing a planar copper layer on the surface of the polymer support layer by magnetron sputtering, which is performed in two steps: magnetron sputtering of the first dense copper layer: the magnetron sputtering gas pressure p1 is 0.2~0.8 MPa; the magnetron sputtering power P1 is 10~20 W / cm². 2 Magnetron sputtering of the second loose copper layer: magnetron sputtering pressure p2 is 0.8~1.5 MPa; magnetron sputtering power P2 is 5~10 W / cm². 2 Furthermore, the following relationship is satisfied between the first dense copper layer and the second loose copper layer sputtered by magnetron sputtering: 0.4 MPa < p2 - p1 < 0.7 MPa, 5 W / cm². 2 <P1-P2<8 W / cm 2 .

[0012] Further, in step S2, the flat copper layer undergoes surface treatment to construct a three-dimensional micro / nano structure. The method used is selected from: Copper nanocone arrays are formed on copper foil by electrochemical deposition; nanowires are grown by reducing copper salts in aqueous solution by hydrothermal method; pits are formed on the copper surface by photoresist mask and etching process; micron-sized pits are etched on the copper surface by laser; or the copper surface is selectively etched by chemical solution.

[0013] Furthermore, step S3, which involves depositing a lithiophilic material film on the surface of the structured composite copper foil, employs magnetron sputtering.

[0014] Further, in step S4, the lithium metal strip is laminated with a structured composite copper foil on which a lithium-loving material film is deposited on the surface using a cold pressing method. The process parameters are to hold the pressure at 220~280 MPa for 3~7 minutes.

[0015] A third aspect of this application provides a negative electrode comprising the aforementioned pre-lithiation functional current collector.

[0016] A fourth aspect of this application provides a battery comprising the aforementioned negative electrode.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a pre-lithiated functional current collector and its preparation method, a negative electrode sheet and a battery. This solution inherits the natural advantage of lightweight composite copper foil and effectively solves many defects of existing lithium metal carrier solutions. It achieves a synergistic unity of lightweight, high safety, high performance and process convenience, and can effectively suppress lithium dendrites and adapt to changes in lithium deposition volume.

[0018] The three-dimensional micro / nano structure of the structured copper layer in this invention, combined with the rational design of the double copper layer, can effectively suppress lithium dendrite growth, eliminating the safety hazard of lithium dendrites piercing the separator and causing short circuits from the root, and further ensuring battery safety. The dense inner copper layer can effectively isolate the electrolyte from the polymer support layer, preventing the polymer support layer from being corroded by the electrolyte, ensuring the stability and durability of the overall current collector structure, and providing a reliable substrate for subsequent lithium deposition. The loose outer copper layer not only provides good support for the construction of the three-dimensional micro / nano structure, but its loose characteristics can also further adapt to the embedding and filling of metallic lithium, improve the bonding tightness between metallic lithium and the copper layer, and at the same time help alleviate the volume expansion pressure during the lithium deposition process, achieving effective adaptation to changes in lithium deposition volume.

[0019] In terms of electrochemical performance, the lithiophilic interface layer can significantly reduce the lithium nucleation barrier and guide the uniform deposition of lithium ions. Combined with the ample lithium deposition space provided by the structured copper layer and the structural advantages of the double copper layer, it can further enhance the suppression effect on lithium dendrites and the adaptability to changes in lithium deposition volume, avoid damage to the electrode due to volume expansion, thereby improving the coulombic efficiency and cycle stability of the battery and extending the battery life.

[0020] In terms of manufacturing process, this solution employs a physical cold-pressing composite process, replacing the complex electrochemical deposition process. This simplifies the production flow, reduces production costs, and allows for precise control of the lithium loading through pre-fabricated lithium strips. The process exhibits strong stability and controllability, making it highly suitable for large-scale industrial production. Furthermore, the overall structure of this solution possesses excellent flexibility, adapting to the application requirements of flexible electronic devices. The interchangeability of materials and structures broadens the solution's applicability, meeting the needs of various scenarios and demonstrating significant industrial application value. Detailed Implementation

[0021] The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the reagents, methods and equipment used are conventional reagents, methods and equipment in this technical field.

[0023] This invention provides a pre-lithiated functional current collector, comprising: The polymer support layer serves as the supporting foundation for the current collector center; A structured copper layer is disposed on at least one side of the polymer support layer, and the surface of the structured copper layer is a three-dimensional micro / nano structure that serves as an anchor point for lithium deposition. A lithiophilic interface layer is applied to the surface of the structured copper layer, and the lithiophilic interface layer is composed of a lithiophilic material. A lithium metal filling layer is laminated onto a structured copper layer with a lithium-philic interface layer on its surface, and the lithium metal in the lithium metal filling layer is embedded and filled into the three-dimensional micro / nano structure of the structured copper layer by pressure.

[0024] The structured copper layer consists of two different magnetron layers: the inner magnetron layer is a dense copper layer used to prevent the electrolyte from contacting the polymer support layer, and the outer magnetron layer is a loose copper layer used for lithium metal embedding and filling. The surface of the outer magnetron layer has a three-dimensional micro-nano structure.

[0025] This invention solves the problems of poor lithiophilicity, uneven lithium deposition, easy dendrite formation, and volume expansion of existing composite copper foils. Through the synergistic design of a polymer support layer, a three-dimensional micro-nano structured copper layer, a lithiophilic interface layer, and a lithium filling layer, it achieves a balance between lightweight, high safety, and high performance of the current collector. At the same time, pressure embedding achieves a firm bond between lithium and the current collector, improving electrode stability and making it suitable for mass production.

[0026] In the double-layer magnetron copper layer, the dense inner layer can effectively isolate the electrolyte from the polymer support layer, avoid substrate corrosion, and ensure structural durability; the loose outer layer is adapted to lithium embedding and filling, strengthens the bonding between lithium and copper layers, further alleviates volume expansion, and improves the overall structural stability and electrochemical reliability of the current collector.

[0027] The three-dimensional micro / nano structure can be a nanocone array, nanowire cluster, porous network structure, or micron-sized pits; the lithiophilic material is selected from one or more of zinc oxide, copper nitride, silver nanoparticles, and gold nanoparticles. The three-dimensional micro / nano structure can provide sufficient lithium deposition space and anchor points, effectively suppress dendrites, and significantly reduce the lithium nucleation barrier through the lithiophilic material, guiding uniform lithium deposition.

[0028] In some embodiments, the magnetron thickness of the inner magnetron layer and the outer magnetron layer is 20~30nm, respectively; the thickness of the lithiophilic interface layer is 10~30nm; and the thickness of the lithium metal filling layer is 10~40μm.

[0029] Within the above thickness parameters, the isolation effect of the dense copper layer, the filling compatibility of the loose copper layer, the lithium-affinity guiding effect of the lithium-affinity layer, and the rationality of the lithium loading of the lithium-filled layer can be ensured, so as to achieve synergistic matching of the structure of each layer, avoid performance degradation caused by improper thickness, and ensure the stability and consistency of current collector performance.

[0030] This invention also provides a method for preparing a pre-lithiated functional current collector, comprising the following steps: S1: A planar copper layer is prepared on the surface of a polymer support layer by magnetron sputtering; S2: Surface treatment is performed on the flat copper layer to construct a three-dimensional micro-nano structure, resulting in a structured composite copper foil; S3: Deposit a thin film of lithium-philic material on the surface of the structured composite copper foil; S4: Under the protection of an inert atmosphere, a lithium metal strip is stacked and pressurized with a structured composite copper foil on which a lithium-loving material film is deposited. Under pressure, the lithium metal flows plastically and fills the three-dimensional micro-nano structure of the structured composite copper foil to form an integrated functional current collector.

[0031] Step S1 involves preparing a planar copper layer on the surface of the polymer support layer by magnetron sputtering, which is performed in two steps: magnetron sputtering of the first dense copper layer: the magnetron sputtering gas pressure p1 is 0.2~0.8 MPa; the magnetron sputtering power P1 is 10~20 W / cm². 2 Magnetron sputtering of the second loose copper layer: magnetron sputtering pressure p2 is 0.8~1.5 MPa; magnetron sputtering power P2 is 5~10 W / cm². 2 Furthermore, the following relationship is satisfied between the first dense copper layer and the second loose copper layer sputtered by magnetron sputtering: 0.4 MPa < p2 - p1 < 0.7 MPa, 5 W / cm².2 <P1-P2<8 W / cm 2 .

[0032] This invention ensures that the density of the dense copper layer matches the porosity of the loose copper layer by defining the core sputtering parameters and parameter relationships of the double-layer magnetron copper layer, thereby improving the bonding force between the two copper layers, avoiding structural defects caused by parameter mismatch, further ensuring the stability of the current collector structure, and providing a reliable substrate for subsequent lithium deposition.

[0033] Step S2 involves surface treatment of the flat copper layer to construct a three-dimensional micro / nano structure. The method used is selected from: Copper nanocone arrays are formed on copper foil by electrochemical deposition; nanowires are grown by reducing copper salts in aqueous solution by hydrothermal method; pits are formed on the copper surface by photoresist mask and etching process; micron-sized pits are etched on the copper surface by laser; or the copper surface is selectively etched by chemical solution.

[0034] Step S3 involves depositing a lithium-loving material film on the surface of the structured composite copper foil using magnetron sputtering. Step S4 involves bonding the lithium metal strip with the structured composite copper foil on which the lithium-loving material film is deposited using a cold pressing method, with process parameters of holding at 220~280 MPa for 3~7 minutes.

[0035] This invention replaces complex processes with magnetron sputtering, surface treatment, and cold pressing composite, simplifying the production process and reducing costs. Simultaneously, by seamlessly connecting the steps, it achieves precise construction of each layer, ensuring uniform lithium filling and strong bonding, making it suitable for large-scale industrial production with strong process controllability. The pre-lithiated functional current collector of this invention inherits the advantages of lightweight, high safety, and high performance of current collectors, while effectively solving the problems of lithium dendrite formation, volume expansion, and poor cycle stability in traditional negative electrode sheets. This improves the electrochemical and safety performance of the negative electrode sheet, making it suitable for various lithium metal batteries.

[0036] The present invention also provides a negative electrode comprising the pre-lithiation functional current collector described above.

[0037] The present invention also provides a battery comprising the aforementioned negative electrode. This battery can balance energy density, safety, and cycle stability, effectively suppress the risk of lithium dendrite short circuits, extend battery life, and reduce battery production costs due to the lightweight current collector and simplified process. It is suitable for various application scenarios such as power batteries, consumer batteries, and flexible electronic devices.

[0038] The technical solution of the present invention will be further described in detail below with reference to specific embodiments: Example 1 This embodiment provides a pre-lithiation anode based on composite copper foil, the preparation method of which includes the following steps: S1: Prepare and process the substrate A composite copper foil substrate is provided, comprising a 4μm thick polymer support layer (selected as polyethylene terephthalate PET). Two magnetron copper layers (inner magnetron layer and outer magnetron layer) are disposed on both the upper and lower surfaces of the polymer support layer. Specifically, the composite copper foil is prepared in two steps using magnetron sputtering, as follows: 1. Magnetron sputtering of the first dense copper layer (inner magnetron layer): A copper target with a purity of 99.99% was selected as the sputtering target material. A DC magnetron sputtering system was used, and the magnetron sputtering gas pressure p1 was controlled at 0.5 Pa, and the magnetron sputtering power P1 was 35 W / cm². 2 A dense copper underlayer is sputtered on the surface of the polymer support layer, with a thickness controlled at 25nm. 2. Magnetron sputtering of the second loose copper layer (outer magnetron layer): Keeping the sputtering target and equipment unchanged, adjust the magnetron sputtering gas pressure p2 to 1.0 Pa and the magnetron sputtering power P2 to 25 W / cm². 2 A loose copper layer is formed by sputtering on the surface of the dense copper layer, with a thickness controlled at 28 nm.

[0039] The above-mentioned composite copper foil is cleaned using the following specific steps: 1. Oxide layer removal: Immerse the composite copper foil in a 0.1 mol / L dilute sulfuric acid aqueous solution and ultrasonically clean it for 5 minutes at room temperature (25℃) to thoroughly remove the oxide layer on the copper surface; 2. Neutralization and rinsing: Rinse the composite copper foil repeatedly with deionized water until the rinsing solution is neutral to avoid residual acid corroding the copper layer; 3. Removal of organic pollutants: The rinsed composite copper foil was transferred into anhydrous ethanol and ultrasonically cleaned for 5 minutes at room temperature to remove the organic pollutants attached to the surface; 4. Drying treatment: After rinsing again with deionized water, place the composite copper foil in a vacuum oven at 60°C and dry for 2 hours to obtain a clean and dry composite copper foil substrate for later use.

[0040] S2: Constructing a structured copper layer A three-electrode system was assembled using S1-treated clean composite copper foil as the working electrode, a high-purity graphite plate as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode.

[0041] Prepare the electrolyte: Prepare an aqueous solution containing 0.8 mol / L copper sulfate (CuSO4) and 2.0 mol / L lactic acid. Adjust the pH of the electrolyte to 9.0 with sodium hydroxide (NaOH), stir well and set aside.

[0042] Fabrication of three-dimensional copper nanocone array: The working electrode was deposited at room temperature (25°C) using a constant potential method. A constant deposition potential of -0.75 V (vs. SCE) was applied to the working electrode, and the deposition time was controlled to be 280 seconds.

[0043] After deposition, the sample was removed, and the surface residual electrolyte was thoroughly rinsed with deionized water and then dried with nitrogen. Finally, highly uniform copper nanocone arrays of about 40 nm were successfully grown on the outer magnetron layers on both sides of the composite copper foil, resulting in a structured composite copper foil.

[0044] S3: Lithophilic modification A zinc oxide (ZnO) lithiophilic interface layer of approximately 28 nm thickness was deposited on the surface of a copper nanocone array of structured composite copper foil using magnetron sputtering. The specific operation is as follows: 1. Target and equipment preparation: A zinc (Zn) target with a purity of 99.99% was selected as the sputtering target, and a DC magnetron sputtering system was used for deposition; 2. Substrate mounting: The structured composite current collector sample prepared by S2 is fixed on the sample stage of the sputtering chamber to ensure that the sample is firmly fixed and the surface is flat; 3. Evacuation and Pre-sputtering: Evacuate the sputtering chamber to a high vacuum background pressure of 5.0 × 10⁻⁶. -4 Pa, then 99.999% pure argon (Ar) is introduced as the working gas, and the gas flow rate is adjusted to stabilize the working pressure in the chamber between 0.5 Pa and 1.0 Pa; before formal deposition, the zinc target is pre-sputtered for 5-10 minutes to clean impurities on the target surface. During the pre-sputtering, the sample is covered with a baffle to avoid impurities contaminating the sample surface. 4. Reactive sputtering: After pre-sputtering is completed, the baffle is removed and formal deposition begins. At the same time, oxygen (O2) with a purity of 99.999% is introduced as the reactive gas, and the flow rate ratio of Ar gas to O2 is controlled at 15:1 to achieve reactive sputtering. 5. Sputtering parameter control: The sputtering power (DC) is set to 90 W, and the substrate temperature is maintained at room temperature (25°C) to avoid high temperature damage to the polymer support layer; through pre-calibration, under the above parameters, a dense ZnO film with a thickness of about 28 nm can be obtained after 30 minutes of deposition; 6. Post-processing: After deposition, turn off the sputtering power supply and gas supply, and cool the sample to room temperature in a vacuum environment before taking it out. At this time, a uniform and firmly bonded ZnO lithiophilic interface layer is formed on the surface of the copper nanocone array, resulting in a functionalized composite current collector.

[0045] S4: Cold pressing composite preparation of pre-lithiated anode In a drying room with a dew point temperature ≥ -45℃, a pre-fabricated lithium metal strip with a thickness of 25μm was prepared. The lithium metal strip and the functionalized composite current collector prepared by S3 were stacked neatly and placed in a cold press, where they were held under pressure of 230 MPa for 5 minutes. Under pressure, the lithium metal underwent plastic flow and fully filled the three-dimensional micro-nano (copper nanocone array) gaps of the structured copper layer, forming a lithium metal filling layer with a thickness of about 25μm. This layer forms a strong mechanical interlock and good electrical contact with the functionalized composite current collector, ultimately forming an integrated electrode, namely the pre-lithiation anode based on composite copper foil described in this invention.

[0046] Example 2 The preparation method of this embodiment is basically the same as that of Example 1, except that in step S2, the pH value of the prepared copper sulfate electrolyte is adjusted to 7.0 by sodium hydroxide (NaOH), the electrolyte concentration is adjusted to 0.6 mol / L copper sulfate (CuSO4) and 1.6 mol / L lactic acid, the deposition potential is adjusted to -0.65 V (vs. SCE), the deposition time is shortened to 220 seconds, and the height of the copper nanocone array is about 35 nm; the remaining steps and parameters are completely consistent with those of Example 1.

[0047] Example 3 The preparation method of this embodiment is basically the same as that of Example 1. The only difference is that in step S3, the thickness of the ZnO lithiophilic interface layer deposited by magnetron sputtering is adjusted to 22 nm, the sputtering power is adjusted to 82 W, and the deposition time is 24 minutes; the other steps and parameters are completely consistent with those of Example 1.

[0048] Example 4 The preparation method in this embodiment is basically the same as that in Example 1, the main difference being: In step S1, the polymer support layer is made of polyimide (PI), with a thickness of 4 μm. Two magnetron copper layers (inner and outer) are provided on both sides. Specifically, it is prepared in two steps by magnetron sputtering, as follows: (1) Magnetron sputtering of the first dense copper layer (inner magnetron layer): A copper target with a purity of 99.99% was selected as the sputtering target material. A DC magnetron sputtering device was used, and the magnetron sputtering gas pressure p1 was controlled at 0.45 Pa and the magnetron sputtering power P1 was 32 W / cm. 2 A dense copper underlayer is sputtered on the surface of the PI support layer, with a thickness controlled to 22nm. (2) Magnetron sputtering of the second loose copper layer (outer magnetron layer): Keeping the sputtering target and equipment unchanged, adjust the magnetron sputtering gas pressure p2 to 0.9 Pa and the magnetron sputtering power P2 to 23 W / cm 2 A loose copper layer is formed by sputtering on the surface of the dense copper layer, with the thickness controlled at 25nm. The cleaning steps are the same as in Example 1; In step S2, the structured copper layer uses a porous mesh structure instead of a copper nanocone array. The preparation method is adjusted as follows: the composite copper foil cleaned in S1 is immersed in an etching solution (composed of 0.3 mol / L ferric chloride + 0.15 mol / L hydrochloric acid) and etched at room temperature for 9 minutes. After removal, it is rinsed with deionized water and dried with nitrogen to obtain a porous mesh structured composite copper foil. The remaining steps (S3 lithophilic modification, S4 cold pressing composite) and parameters are completely consistent with those in Example 1.

[0049] Example 5 The preparation method of this embodiment is basically the same as that of Example 1, except that in step S3, copper nitride (Cu3N) is used instead of ZnO for the lithiophilic interface layer, and magnetron sputtering is used for deposition. The target material is 99.99% Cu3N target, the sputtering power is adjusted to 95 W, the deposition time is 28 minutes, and a Cu3N lithiophilic layer with a thickness of about 26 nm is obtained. The other sputtering parameters and steps are the same as those in Example 1.

[0050] Example 6 The preparation method in this embodiment is basically the same as that in Example 1, the only difference being that in step S1, both magnetron copper layers use the minimum thickness limit (20nm) specified in the patent. The specific steps are as follows: 1. Magnetron sputtering of the first dense copper layer (inner magnetron layer): A copper target with a purity of 99.99% was selected as the sputtering target material. A DC magnetron sputtering system was used, and the magnetron sputtering gas pressure p1 was controlled at 0.4 Pa, and the magnetron sputtering power P1 was 30 W / cm². 2 A dense copper underlayer is sputtered on the surface of the PET support layer, with a thickness controlled at 20nm. 2. Magnetron sputtering of the second loose copper layer (outer magnetron layer): Keeping the sputtering target and equipment unchanged, adjust the magnetron sputtering gas pressure p2 to 0.8 Pa and the magnetron sputtering power P2 to 20 W / cm². 2 The sputtering thickness is controlled to be 20nm; The remaining steps (S1 cleaning, S2~S4) and parameters were adapted and adjusted to those in Example 1: S2 The electrolyte concentration was reduced to 0.5 mol / L copper sulfate and 1.5 mol / L lactic acid, the deposition time was 200 seconds, and the copper nanocone array height was 32 nm; S3 The ZnO layer thickness was 20 nm, the sputtering power was 80 W, and the deposition time was 20 minutes; S4 The lithium metal strip thickness was 23 μm, the cold pressing pressure was 220 MPa, the holding pressure was 5 minutes, and the lithium metal filling layer thickness was approximately 23 μm.

[0051] Example 7 The preparation method in this embodiment is basically the same as that in Example 1, the only difference being that in step S1, both magnetron copper layers use the upper limit of thickness (30nm) specified in the patent. The specific steps are as follows: 1. Magnetron sputtering of the first dense copper layer (inner magnetron layer): A copper target with a purity of 99.99% was selected as the sputtering target material. A DC magnetron sputtering system was used, and the magnetron sputtering gas pressure p1 was controlled at 0.6 Pa, and the magnetron sputtering power P1 was 40 W / cm². 2 A dense copper underlayer is sputtered on the surface of the PET support layer, with a thickness controlled at 30nm. 2. Magnetron sputtering of the second loose copper layer (outer magnetron layer): Keeping the sputtering target and equipment unchanged, adjust the magnetron sputtering gas pressure p2 to 1.1 Pa and the magnetron sputtering power P2 to 30 W / cm². 2 The sputtering thickness is controlled at 30nm; The remaining steps (S1 cleaning, S2~S4) and parameters were adapted and adjusted to those in Example 1: S2 electrolyte concentration was increased to 1.0 mol / L copper sulfate and 2.2 mol / L lactic acid, deposition time was 320 seconds, and copper nanocone array height was 45 nm; S3 ZnO layer thickness was 30 nm, sputtering power was 95 W, and deposition time was 32 minutes; S4 lithium metal strip thickness was 27 μm, cold pressing pressure was 240 MPa, holding pressure was 6 minutes, and lithium metal filling layer thickness was approximately 27 μm.

[0052] Comparative Example 1 This comparative example uses ordinary composite copper foil (i.e., composite copper foil without S2 structuring treatment and S3 lithiophilic modification, whose structure is a 4μm PET polymer support layer + two magnetron sputtering layers on each side) as the lithium metal carrier. The two magnetron sputtering layers are prepared in two steps by magnetron sputtering, as follows: 1. Magnetron sputtering of the first dense copper layer (inner magnetron layer): A copper target with a purity of 99.99% was selected as the sputtering target material. A DC magnetron sputtering system was used, and the magnetron sputtering gas pressure p1 was controlled at 0.5 Pa, and the magnetron sputtering power P1 was 34 W / cm². 2 A dense copper underlayer is sputtered on the surface of the PET support layer, with a thickness controlled at 24nm. 2. Magnetron sputtering of the second loose copper layer (outer magnetron layer): Keeping the sputtering target and equipment unchanged, adjust the magnetron sputtering gas pressure p2 to 0.95 Pa and the magnetron sputtering power P2 to 24 W / cm². 2 A loose copper layer is formed by sputtering on the surface of the dense copper layer, with the thickness controlled at 26nm. The ordinary composite copper foil was directly cold-pressed with a 25μm prefabricated lithium metal strip according to step S4 of Example 1 to prepare a comparative negative electrode.

[0053] Comparative Example 2 The preparation method of this comparative example is basically the same as that of Example 1. The only difference is that the S3 lithophile modification step is omitted. That is, the structured composite copper foil (copper nanocone array, height 40nm) is directly cold-pressed with the pre-made lithium metal strip. The other steps and parameters are completely consistent with those of Example 1.

[0054] Comparative Example 3 The preparation method of this comparative example is basically the same as that of Example 1, except that the S2 structuring treatment step is omitted. That is, the ordinary composite copper foil is directly modified by S3 lithophilization and then cold-pressed with the pre-made lithium metal strip. The two magnetron copper layers are prepared in two steps by magnetron sputtering. The specific steps are as follows: 1. Magnetron sputtering of the first dense copper layer (inner magnetron layer): A copper target with a purity of 99.99% was selected as the sputtering target material. A DC magnetron sputtering system was used, and the magnetron sputtering gas pressure p1 was controlled at 0.48 Pa, and the magnetron sputtering power P1 was 33 W / cm². 2 A dense copper underlayer is sputtered on the surface of the PET support layer, with a thickness controlled at 23nm. 2. Magnetron sputtering of the second loose copper layer (outer magnetron layer): Keeping the sputtering target and equipment unchanged, adjust the magnetron sputtering gas pressure p2 to 0.92 Pa and the magnetron sputtering power P2 to 22 W / cm². 2 A loose copper layer is formed by sputtering on the surface of the dense copper layer, with the thickness controlled at 27nm. The remaining steps and parameters are completely consistent with those in Example 1.

[0055] Comparative Example 4 The preparation method of this comparative example is basically the same as that of Example 1, except that in step S1, the magnetron sputtering parameters of the two magnetron copper layers do not satisfy the relationship p2-p1>0.4Pa. The specific steps are as follows: 1. Magnetron sputtering of the first dense copper layer (inner magnetron layer): A copper target with a purity of 99.99% was selected as the sputtering target material. A DC magnetron sputtering system was used, and the magnetron sputtering gas pressure p1 was controlled at 0.5 Pa, and the magnetron sputtering power P1 was 35 W / cm². 2 A dense copper underlayer is sputtered on the surface of the PET support layer, with a thickness controlled at 25nm. 2. Magnetron sputtering of the second loose copper layer (outer magnetron layer): Keeping the sputtering target and equipment unchanged, adjust the magnetron sputtering gas pressure p2 to 0.8 Pa and the magnetron sputtering power P2 to 25 W / cm². 2 The sputtering thickness is controlled to be 28nm; The remaining steps (S1 cleaning, S2~S4) and parameters are completely consistent with those in Example 1.

[0056] Comparative Example 5 The preparation method of this comparative example is basically the same as that of Example 1, the only difference being that in step S1, the magnetron sputtering parameters of the two magnetron copper layers do not satisfy P1-P2 < 8W / cm 2 The relationship is established, and the specific steps are as follows: 1. Magnetron sputtering of the first dense copper layer (inner magnetron layer): A copper target with a purity of 99.99% was selected as the sputtering target material. A DC magnetron sputtering system was used, and the magnetron sputtering gas pressure p1 was controlled at 0.5 Pa, and the magnetron sputtering power P1 was 36 W / cm². 2 A dense copper underlayer is sputtered on the surface of the PET support layer, with a thickness controlled at 25nm. 2. Magnetron sputtering of the second loose copper layer (outer magnetron layer): Keeping the sputtering target and equipment unchanged, adjust the magnetron sputtering gas pressure p2 to 1.0 Pa and the magnetron sputtering power P2 to 26 W / cm². 2 The sputtering thickness is controlled to be 28nm; The remaining steps (S1 cleaning, S2~S4) and parameters are completely consistent with those in Example 1.

[0057] The test results for each case are shown in Table 1.

[0058] Table 1

[0059] Test results show that: In Example 2, lowering the electrolyte pH resulted in a decrease in both the first-week coulombic efficiency and cycle capacity retention. Lowering the pH reduces the growth uniformity of the copper nanocone array, thus affecting the uniformity of the lithiophilic interface layer coverage. Maintaining the electrolyte pH within a suitable range is beneficial for improving the growth quality of the structured copper layer and battery performance. In Example 3, reducing the lithiophilic layer thickness led to a decrease in both the first-week coulombic efficiency and cycle capacity retention. Insufficient lithiophilic layer thickness weakens the guiding effect on lithium nucleation, resulting in decreased lithium deposition uniformity. A lithiophilic layer of suitable thickness better balances lithiophilic effect and battery cycle stability.

[0060] In Example 4, after changing the polymer support layer material and adjusting the morphology of the structured copper layer, the battery performance was still close to that of Example 1.

[0061] Example 5 uses other lithiophilic materials as substitutes, and the battery performance is comparable and slightly improved. Different lithiophilic interface layer materials can meet the needs of different application scenarios.

[0062] Compared with Example 1, the negative electrodes prepared using the boundary values ​​of magnetron sputtering parameters in Examples 6 and 7 still maintain good electrochemical performance.

[0063] When using ordinary composite copper foil without structuring and lithophilic modification in Comparative Example 1, the battery performance was significantly reduced. This is because ordinary copper foil has poor lithophilicity, cannot guide uniform lithium deposition, is prone to lithium dendrite formation, and is difficult to adapt to volume changes.

[0064] Comparative Example 2 shows that when only a structured copper layer is used without lithophilic modification, the battery performance is significantly reduced. This indicates that although the structured copper layer can provide lithium deposition space, the copper surface is not lithophilic enough and the nucleation barrier is high, which still makes it easy for uneven lithium deposition and dendrite growth to occur.

[0065] Comparative Example 3, which only underwent lithophilic modification without constructing a structured copper layer, also showed poor battery performance. This is because the flat copper foil has a small specific surface area and insufficient deposition space, which cannot adapt to the volume changes of lithium deposition, and dendrite and expansion problems still exist.

[0066] Compared with the example, when the magnetron sputtering gas pressure difference is lower than the limit range, the battery performance deteriorates. Insufficient gas pressure difference will lead to a decrease in the bonding force between the two copper layers, and the pore structure will not meet expectations, making it difficult to adapt to changes in lithium deposition volume.

[0067] Compared with the embodiment, when the difference in magnetron sputtering power exceeds the limit, the battery performance deteriorates. Excessive power difference leads to poor matching of the copper layer structure, weak interface bonding, easy peeling, and affects the conductivity and stability of the electrode.

[0068] In summary, this invention utilizes the synergistic effect of a double-layer magnetron-controlled flat copper layer and a structured copper layer. The dense inner copper layer isolates the electrolyte and ensures structural stability, while the loose outer copper layer provides a substrate for the three-dimensional micro / nano structure. The structured copper layer provides lithium deposition space and anchor points, adapts to volume changes, and suppresses lithium dendrites. Key parameter control further enhances the bonding effect between the two layers. The lithiophilic layer lowers the lithium nucleation barrier and guides uniform deposition, forming a dual guarantee of anchor point positioning and lithiophilic guidance with the structured copper layer, solving the problem of uneven lithium deposition and improving bonding strength and battery performance. The cold-pressing process facilitates the embedding of metallic lithium into the gaps between the structured copper layers, achieving integrated fusion of components, ensuring good electrical contact, fully leveraging the synergistic effect of each structure, ultimately improving battery coulombic efficiency and cycle stability, while also ensuring the versatility of the solution.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A pre-lithiated functional current collector, characterized in that, include: The polymer support layer serves as the supporting foundation for the current collector center; A structured copper layer is disposed on at least one side of the polymer support layer, wherein the surface of the structured copper layer is a three-dimensional micro / nano structure serving as lithium deposition anchor points; A lithiophilic interface layer is applied to the surface of the structured copper layer, and the lithiophilic interface layer is composed of a lithiophilic material. A lithium metal filling layer is laminated onto a structured copper layer with a lithium-philic interface layer on its surface, and the lithium metal in the lithium metal filling layer is embedded and filled into the three-dimensional micro / nano structure of the structured copper layer by pressure.

2. The pre-lithiated functional current collector according to claim 1, characterized in that: The structured copper layer consists of two different magnetron layers: the inner magnetron layer is a dense copper layer and the outer magnetron layer is a loose copper layer, and the surface of the outer magnetron layer has a three-dimensional micro-nano structure.

3. The pre-lithiation functional current collector according to claim 1, characterized in that: The three-dimensional micro / nano structure is a nanocone array, nanowire cluster, porous network structure, or micron-sized pits; the lithiophilic material is selected from one or more of zinc oxide, copper nitride, silver nanoparticles, and gold nanoparticles.

4. The pre-lithiation functional current collector according to claim 2, characterized in that: The magnetron thickness of the inner and outer magnetron layers is 20-30 nm, respectively; the thickness of the lithiophilic interface layer is 10-30 nm; and the thickness of the lithium metal filling layer is 10-40 μm.

5. The method for preparing the pre-lithiated functional current collector according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1: A planar copper layer is prepared on the surface of a polymer support layer by magnetron sputtering; S2: The flat copper layer is surface treated to construct a three-dimensional micro-nano structure, thereby obtaining a structured composite copper foil; S3: Deposit a thin film of lithium-philic material on the surface of the structured composite copper foil; S4: Under the protection of an inert atmosphere, a lithium metal strip is stacked and pressurized with a structured composite copper foil on which a lithium-loving material film is deposited. Under pressure, the lithium metal flows plastically and fills the three-dimensional micro-nano structure of the structured composite copper foil to form an integrated functional current collector.

6. The method for preparing the pre-lithiated functional current collector according to claim 5, characterized in that: Step S1 involves preparing a planar copper layer on the surface of the polymer support layer by magnetron sputtering, which is performed in two steps: magnetron sputtering of the first dense copper layer: the magnetron sputtering gas pressure p1 is 0.2~0.8 MPa; the magnetron sputtering power P1 is 10~20 W / cm². 2 Magnetron sputtering of the second loose copper layer: magnetron sputtering pressure p2 is 0.8~1.5 MPa; magnetron sputtering power P2 is 5~10 W / cm². 2 Furthermore, the following relationship is satisfied between the first dense copper layer and the second loose copper layer sputtered by magnetron sputtering: 0.4 MPa < p2 - p1 < 0.7 MPa, 5 W / cm². 2 <P1-P2<8 W / cm 2 .

7. The method for preparing the pre-lithiated functional current collector according to claim 5, characterized in that: Step S2 involves surface treatment of the flat copper layer to construct a three-dimensional micro / nano structure. The method used is selected from: Copper nanocone arrays are formed on copper foil by electrochemical deposition; nanowires are grown by reducing copper salts in aqueous solution by hydrothermal method; pits are formed on the copper surface by photoresist mask and etching process; micron-sized pits are etched on the copper surface by laser; or the copper surface is selectively etched by chemical solution.

8. The method for preparing the pre-lithiated functional current collector according to claim 5, characterized in that: Step S3 involves depositing a lithium-loving material film on the surface of the structured composite copper foil using magnetron sputtering. Step S4 involves bonding the lithium metal strip with the structured composite copper foil on which the lithium-loving material film is deposited using a cold pressing method, with process parameters of holding at 220~280 MPa for 3~7 minutes.

9. A negative electrode sheet, characterized in that: It includes the pre-lithiation functional current collector as described in any one of claims 1 to 4.

10. A battery, characterized in that: It includes the negative electrode sheet as described in claim 9.

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