Method of making a current collector

Abstract

The present application relates to the technical field of battery, and especially relates to a current collector, a preparation method thereof, a negative electrode sheet and a lithium metal battery. The current collector comprises a copper current collector body, a reduced graphene oxide film and cuprous oxide. The reduced graphene oxide film is combined on the surface of the copper current collector body, and the reduced graphene oxide film and the copper current collector body have opposite charges. At least part of the cuprous oxide is formed between the copper current collector body and the reduced graphene oxide film. The preparation method of the current collector comprises the following steps: performing electrodeposition on the copper current collector body arranged in a graphene oxide suspension, so that the reduced graphene oxide film is deposited on the copper current collector body, and the cuprous oxide generated through in-situ reaction is formed between the copper current collector body and the reduced graphene oxide film; wherein the pH of the graphene oxide suspension is 6.5-7.1.

Description

Technical Field

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

[0002] Compared to current graphite anodes, lithium metal anodes possess ultra-high theoretical specific capacity, lower electrode potential, and lower density. When matched with sulfur- and oxygen-containing cathodes, they exhibit high energy density. Therefore, lithium metal batteries using lithium metal anodes are considered one of the next-generation high-energy-density battery candidates.

[0003] Current lithium metal anodes consist of a copper current collector and an active material layer supported on the surface of the copper current collector, with the active material layer being a lithium metal layer. The copper current collector not only supports the active material but also collects electrons generated by the electrochemical reaction into an external circuit, thus achieving the conversion of chemical energy into electrical energy. However, due to copper's lithium-phobic nature, lithium tends to form dendritic lithium deposits during deposition, which limits the application of copper current collectors in lithium metal anodes.

[0004] While copper current collectors can be used to stabilize lithium metal anodes, current current collector modification materials are prone to detachment and uneven distribution on the current collector surface. Consequently, due to the deviation in material bonding force and uneven distribution, the modification effect on copper current collectors is limited. Summary of the Invention

[0005] To address the aforementioned technical problems, this application discloses a method for preparing a current collector. The reduced graphene oxide film and the copper current collector body in the current collector have strong bonding force, the current collector can conduct electricity uniformly and the lithium-affinity sites are evenly distributed, and the growth of lithium dendrites is suppressed by cuprous oxide, thereby improving the cycle stability of the battery.

[0006] In a first aspect, embodiments of this application provide a current collector, comprising:

[0007] Copper current collector body;

[0008] A reduced graphene oxide film, wherein the reduced graphene oxide film is bonded to the surface of the copper current collector body, and the reduced graphene oxide film and the copper current collector body carry opposite charges; and

[0009] Cuprous oxide, at least a portion of which is distributed between the copper current collector body and the reduced graphene oxide film.

[0010] Optionally, a portion of the cuprous oxide is distributed on the side of the reduced graphene oxide film away from the copper current collector body and within the reduced graphene oxide film.

[0011] Optionally, the conductivity of the copper current collector body is x in S / m, and the conductivity of the reduced graphene oxide film is y in S / m; wherein, 5.5 × 10 7 S / m≤x≤6×10 7 S / m, 7×10 3 S / m≤y≤30×10 3 S / m, x / y≥10 3 ;

[0012] And / or, the thickness of the reduced graphene oxide film is 1 μm to 20 μm.

[0013] Secondly, embodiments of this application provide a method for preparing a current collector, comprising the following steps:

[0014] Electrodeposition is performed on the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and cuprous oxide is formed between the copper current collector body and the reduced graphene oxide film through an in-situ reaction; wherein the pH of the graphene oxide suspension is 6.5~7.1.

[0015] Optionally, the reduced graphene oxide film has cuprous oxide generated through an in-situ reaction.

[0016] Optionally, the graphene oxide suspension is composed of graphene oxide and water with a conductivity ≤20 μS / m;

[0017] And / or, the concentration of graphene oxide in the graphene oxide suspension is 1 mg / mL to 5 mg / mL.

[0018] Optionally, prior to the step of electrodepositing the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming cuprous oxide generated through an in-situ reaction between the copper current collector body and the reduced graphene oxide film, the method for preparing the current collector further includes:

[0019] The copper current collector body is cut into a piece with an area of ​​a×b, where the unit is cm. 2 The copper current collector body is immersed in a first cleaning liquid for ultrasonic cleaning; the copper current collector body is immersed in an acid solution to remove the oxide layer on the surface of the copper current collector body.

[0020] The counter electrode is cut into pieces with an area of ​​c × d, and the unit is cm. 2, immerse the counter electrode in a second cleaning liquid and perform ultrasonic cleaning; where 0 < a ≤ 100 cm, 0 < b ≤ 10 cm; 0 < c ≤ 110 cm, 0 < d ≤ 15 cm; and 0.01 cm ≤ (c - a) ≤ 10 cm, 0.01 cm ≤ (d - b) ≤ 5 cm;

[0021] The step of electro-depositing the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming the cuprous oxide generated by an in-situ reaction between the copper current collector body and the reduced graphene oxide film includes:

[0022] Using an electrochemical workstation, with the copper current collector body as the working electrode, place the counter electrode, reference electrode, and the working electrode in the graphene oxide suspension, and perform electro-deposition using chronoamperometry.

[0023] Optionally, in the step of electro-depositing the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming the cuprous oxide generated by an in-situ reaction between the copper current collector body and the reduced graphene oxide film, the electro-deposition voltage range is 0.01V to 10 V, and the electro-deposition time is 10 s to 3600 s;

[0024] And / or, after the step of electro-depositing the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming the cuprous oxide generated by an in-situ reaction between the copper current collector body and the reduced graphene oxide film, the method for preparing the current collector further includes:

[0025] Place the electro-deposited copper current collector body in a vacuum environment and dry it at a temperature of 55°C to 65°C to obtain the current collector.

[0026] In a third aspect, an embodiment of the present application provides a negative electrode sheet, the negative electrode sheet having the current collector as described in the first aspect or the current collector prepared by the method for preparing the current collector as described in the second aspect, and a negative electrode active material layer loaded on the surface of the current collector; the negative electrode active material layer is a lithium metal layer.

[0027] In a fourth aspect, an embodiment of the present application provides a lithium metal battery, including:

[0028] A positive electrode sheet;

[0029] A negative electrode sheet;

[0030] A separator, wherein the separator is disposed between the positive electrode and the negative electrode to form a battery cell; and

[0031] Electrolyte, wherein the electrolyte is injected into the battery cell;

[0032] The negative electrode sheet has a current collector prepared by the current collector preparation method described in the first aspect or the current collector preparation method described in the second aspect, and a negative electrode active material layer loaded on the surface of the current collector; the negative electrode active material layer is a lithium metal layer.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] This application provides a current collector in which the reduced graphene oxide film and the copper current collector body have opposite charges, resulting in a strong interaction between them. This interaction makes the reduced graphene oxide film less prone to cracking and effectively inhibits its detachment from the copper current collector body surface, thus helping to maintain the uniformity and density of the reduced graphene oxide film. The uniform and dense reduced graphene oxide film has a more uniform current density in the planar direction, thereby inducing lithium metal loaded on the surface of the current collector to be deposited planarly on its surface, which is beneficial for inducing uniform nucleation and deposition of lithium metal.

[0035] Meanwhile, cuprous oxide is distributed between the copper current collector and the reduced graphene oxide film. This cuprous oxide exhibits good lithiophilicity, which can lower the lithium nucleation barrier. When the current collector in this embodiment is loaded with active lithium metal, the presence of cuprous oxide can induce uniform nucleation and deposition of lithium metal. Since cuprous oxide, as a lithiophilic site, induces uniform lithium nucleation, it can effectively suppress lithium dendrite growth, thereby improving the coulombic efficiency of the battery.

[0036] In summary, the current collector of this application exhibits strong adhesion between the reduced graphene oxide film and the copper current collector bulk, the reduced graphene oxide film is not easily detached, and the current collector provides uniform conductivity with a uniform distribution of lithium-affinity sites. This application improves the cycle stability and coulombic efficiency of the battery by suppressing lithium dendrite growth through cuprous oxide. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a current collector according to Example 1;

[0039] Figure 2 This is a flowchart of a method for preparing a current collector according to Example 1;

[0040] Figure 3 This is a photograph of a current collector according to Example 1;

[0041] Figure 4 This is a photograph of a current collector as shown in Comparative Example 1;

[0042] Figure 5 This is a scanning electron microscope image of a current collector according to Example 1;

[0043] Figure 6 Example 1 shows a 5 mAh cm⁻¹ deposition on a current collector. -2 Scanning electron microscope image of lithium;

[0044] Figure 7 5 mAh cm⁻¹ was deposited on a current collector in Comparative Example 1. -2 Scanning electron microscope image of lithium;

[0045] Figure 8 This is a scanning electron microscope image of a current collector in Comparative Example 3;

[0046] Figure 9 This is the XRD pattern of a current collector according to Example 1;

[0047] Figure 10 This is the XRD pattern of a current collector in Comparative Example 2;

[0048] Figure 11 This is an EDS-mapping selection map of a current collector according to Example 1;

[0049] Figure 12 yes Figure 11 EDS-mapping image of C element in the corresponding range;

[0050] Figure 13 yes Figure 11 EDS-mapping image of the O element in the corresponding range;

[0051] Figure 14 yes Figure 11 EDS-mapping image of Cu element in the corresponding range.

[0052] Explanation of icon numbers:

[0053] 100. Copper current collector body; 200. Reduced graphene oxide film; 300. Cuprous oxide. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Lithium metal anodes in lithium metal batteries possess advantages such as high theoretical specific capacity and low electrode potential. However, the copper current collector in the lithium metal anode exhibits lithium-phobic properties, leading to a series of problems such as lithium dendrite formation. Therefore, it is necessary to modify the copper current collector in the lithium metal anode to be lithium-friendly. Graphene oxide can be used to modify the copper current collector. The reaction between graphene oxide and the copper current collector forms a reduced graphene oxide film on the copper current collector. The reduced graphene oxide film contains lithium-friendly oxygen-containing groups, thus solving the lithium-phobic problem of the copper current collector. However, the inventors of this application have found that the bonding force between the reduced graphene oxide film and the copper current collector is poor. This leads to the reduced graphene oxide film easily detaching from the copper current collector, resulting in an uneven distribution of the reduced graphene oxide film. This uneven distribution of reduced graphene oxide leads to an uneven distribution of lithium-friendly sites on the current collector, resulting in poor conductivity uniformity of the electrode with the aforementioned current collector.

[0056] Based on the above analysis, this application provides a method for preparing a current collector. The current collector exhibits a strong interaction force between the reduced graphene oxide film and the copper current collector body due to their opposite charges. This interaction force makes the reduced graphene oxide film less prone to cracking, effectively inhibiting its detachment from the copper current collector body surface, and helping to maintain the uniformity and density of the reduced graphene oxide film. Furthermore, the lithium affinity of the current collector is further improved by the cuprous oxide distributed between the copper current collector body and the reduced graphene oxide layer.

[0057] The technical solution of the present invention will now be described in conjunction with the embodiments and accompanying drawings.

[0058] The first aspect, such as Figure 1 As shown, this application provides a current collector including a copper current collector body 100, a reduced graphene oxide film 200, and cuprous oxide 300. The reduced graphene oxide film 200 is bonded to the surface of the copper current collector body 100, and the reduced graphene oxide film 200 and the copper current collector body 100 carry opposite charges. At least a portion of the cuprous oxide 300 is formed between the copper current collector body 100 and the reduced graphene oxide film 200.

[0059] The reduced graphene oxide film 200 and the copper current collector 100 have opposite charges, resulting in a strong interaction between them. This interaction makes the reduced graphene oxide film 200 less prone to cracking, effectively inhibiting its detachment from the copper current collector 100 surface. This helps maintain the uniformity and density of the reduced graphene oxide film 200, preventing cracking or detachment. The uniformly distributed lithium-loving oxygen-containing functional groups on the reduced graphene oxide film 200 provide more lithium nucleation sites. The uniform and dense reduced graphene oxide film 200 exhibits a more uniform current density in the planar direction, inducing lithium metal loaded on the current collector surface to deposit planarly on its surface. This promotes uniform nucleation and deposition of lithium metal, thereby improving stability during cycling. The aforementioned planar direction refers to all directions on the plane P where the reduced graphene oxide film 200 is located. For details, please refer to... Figure 1 , Figure 1 In this context, Y0-Y1 represents the thickness direction of the current collector, and plane P lies in... Figure 1 The direction perpendicular to Y0-Y1 is one example of the aforementioned planar directions. Furthermore, the reduced graphene oxide film 200 exhibits excellent wettability with the electrolyte, ensuring sufficient contact between the electrode fabricated using this current collector and the electrolyte, thus reducing electrode polarization.

[0060] Meanwhile, cuprous oxide 300 is distributed between the copper current collector body 100 and the reduced graphene oxide film 200. Lithium ions can bind to this portion of cuprous oxide 300 through the reduced graphene oxide film 200. This cuprous oxide 300 exhibits good lithiophilicity, lowering the lithium nucleation barrier. This is because lithium ions selectively react with cuprous oxide 300 to form lithium oxide. Since the formed lithium oxide is itself a conductor of lithium ions, it can further promote the uniform distribution of lithium ions, thereby facilitating the uniform deposition of metallic lithium.

[0061] The cuprous oxide 300 of this application is formed by in-situ reaction of graphene oxide with the copper current collector body 100. The cuprous oxide 300 generated by the in-situ reaction also exhibits a uniform distribution. Since the cuprous oxide 300, as a lithiophilic site, is uniformly dispersed on the surface of the current collector, when the current collector of this application embodiment is loaded with active material lithium metal, the presence of cuprous oxide 300 can induce uniform nucleation and deposition of lithium metal. Because the cuprous oxide 300, as a lithiophilic site, induces uniform lithium nucleation, it can effectively suppress lithium dendrite growth and improve the coulombic efficiency of the battery.

[0062] In summary, the reduced graphene oxide film 200 and the copper current collector body 100 exhibit strong adhesion, the reduced graphene oxide film 200 is not easily detached, and the current collector demonstrates good conductivity uniformity and a uniform distribution of lithiophilic sites. Since lithium dendrite growth leads to instability at the electrode-electrolyte interface during battery cycling, and the growth of lithium dendrites continuously consumes the electrolyte and causes irreversible deposition of metallic lithium, resulting in dead lithium and low coulombic efficiency, this application utilizes cuprous oxide 300 to suppress lithium dendrite growth, thereby improving the battery's cycle stability and coulombic efficiency.

[0063] Furthermore, some cuprous oxide 300 is distributed on the side of the reduced graphene oxide film 200 away from the copper current collector 100 and within the reduced graphene oxide film 200 itself. This portion of cuprous oxide 300 distributed on the side of the reduced graphene oxide film 200 away from the copper current collector 100 can directly contact the active material lithium metal loaded on the current collector, directly inducing uniform nucleation and deposition of lithium metal, thereby further improving the lithium affinity of the current collector. This portion of cuprous oxide 300 distributed within the reduced graphene oxide film 200 can effectively inhibit the aggregation of reduced graphene oxide, which is beneficial for electrolyte wetting, thereby accelerating the lithium-ion transport rate.

[0064] Preferably, the conductivity of the copper current collector body 100 is x in S / m, and the conductivity of the reduced graphene oxide film 200 is y in S / m; wherein, 5.5 × 10 7 S / m≤x≤6×10 7 S / m, 7×10 3 S / m≤y≤30×10 3 S / m, x / y≥10 3 In other words, the conductivity of the copper current collector 100 is significantly better than that of the reduced graphene oxide film 200. The two form a conductivity gradient, causing more electrons to concentrate in the copper current collector 100, thus inducing preferential nucleation of lithium metal on the copper current collector 100. The uniform deposition of the reduced graphene oxide film 200 on the surface of the copper current collector results in a uniform current density distribution on the current collector surface, which can induce uniform deposition of lithium metal on the surface of the reduced graphene oxide film 200.

[0065] If the thickness of the reduced graphene oxide film 200 is less than 1 μm, the lithophilic modification effect on the copper current collector body 100 is not ideal, which is not conducive to controlling lithium deposition behavior. If the thickness of the reduced graphene oxide film 200 is greater than 20 μm, the reduced graphene oxide film 200 is prone to detachment due to excessive film thickness, and the bond between the reduced graphene oxide film 200 and the copper current collector body 100 is not tight. Preferably, the thickness of the reduced graphene oxide film 200 is 1 μm to 20 μm, including any value within this thickness range, such as 1 μm, 5 μm, 10 μm, and 20 μm.

[0066] Secondly, embodiments of this application provide a method for preparing a current collector, comprising the following steps:

[0067] Electrodeposition is performed on a copper current collector body placed in a graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and cuprous oxide is formed between the copper current collector body and the reduced graphene oxide film through an in-situ reaction; wherein the pH of the graphene oxide suspension is 6.5~7.1.

[0068] In this embodiment, a reduced graphene oxide film is obtained by electrodeposition on a copper current collector. The term "electrodeposition" refers to the formation of a reduced graphene oxide film on a working electrode using an electrochemical method through a reduction reaction process.

[0069] The reduced graphene oxide film and the copper current collector body prepared by electrodeposition have opposite charges and a strong interaction force. This interaction force makes the reduced graphene oxide film less prone to cracking and effectively inhibits the reduced graphene oxide film from falling off the surface of the copper current collector body.

[0070] Although the copper current collector substrate is functionalized using an immersion method with graphene oxide (see Comparative Example 1 for details), the current collector prepared by this method has difficulty in ensuring the uniformity of the reduced graphene oxide layer, resulting in low reproducibility and hindering large-scale production. Furthermore, the poor adhesion between the reduced graphene oxide layer and the copper current collector substrate can cause the reduced graphene oxide layer to detach, leading to poor conductivity uniformity and uneven distribution of lithium-affinity sites on the electrode. This facilitates the formation of lithium dendrites and volume expansion, causing structural collapse during cycling and consequently reducing the battery's cycle stability.

[0071] Compared to the immersion method, electrodeposition offers advantages such as tighter film bonding, high repeatability, and scalability for mass production. More importantly, the reduced graphene oxide layer prepared by electrodeposition exhibits superior uniformity. The uniformly distributed reduced graphene oxide film displays a uniform current density in the planar direction, thereby inducing planar deposition of lithium metal on its surface, which is beneficial for uniform nucleation and deposition of lithium metal. The cuprous oxide generated in situ also exhibits uniform distribution, with cuprous oxide, acting as lithiophilic sites, uniformly dispersed on the surface of the current collector, thus inducing uniform nucleation and deposition of lithium metal.

[0072] Furthermore, although reduced graphene oxide films can be deposited on copper-based materials by electrodeposition in an acidic environment, this only produces reduced graphene oxide films, making them easy to separate from the copper-based materials, and cannot retain cuprous oxide.

[0073] Based on the above analysis, this application selects a neutral or near-neutral electrodeposition environment—a graphene oxide suspension with a pH of 6.5–7.1—for electrodeposition. During the graphene oxide electrodeposition process, a reduction reaction occurs. The oxide functional groups removed during this reduction reaction react with copper, causing the copper current collector to react in situ with the graphene oxide, thereby forming cuprous oxide between the copper current collector and the reduced graphene oxide film. Compared to related technologies that require an additional oxidation step to oxidize copper to cuprous oxide, this application simultaneously forms cuprous oxide during the electrodeposition process, simplifying the process. Furthermore, the in-situ formed cuprous oxide exhibits better bonding with both the copper current collector and the reduced graphene oxide film.

[0074] In neutral or near-neutral graphene oxide suspensions (pH 6.5–7.1), cuprous oxide is retained on the copper current collector. This is because if the pH is less than 6.5, cuprous oxide is easily disproportionated to divalent copper, preventing its retention on the copper current collector. Since the reaction for cuprous oxide formation mainly occurs between the copper current collector and the reduced graphene oxide film, at least some cuprous oxide is located between them. It can be understood that cuprous oxide can not only form between the copper current collector and the reduced graphene oxide film, but also, due to copper diffusion, when copper diffuses to the side of the reduced graphene oxide film away from the copper current collector, cuprous oxide forms on that side as well. When copper diffuses into the reduced graphene oxide film, it reacts in situ with graphene oxide to generate cuprous oxide. Furthermore, gaps exist in the reduced graphene oxide film prepared by electrodeposition, allowing lithium ions generated by the lithium metal layer loaded on the current collector surface to pass through these gaps and bind to cuprous oxide, which serves as a lithiophilic site.

[0075] Furthermore, cuprous oxide formed by in-situ reaction is present on the reduced graphene oxide film. This part of the cuprous oxide can directly contact the lithium metal layer loaded on the current collector, further improving the lithiophilic property of the surface of the current collector.

[0076] Furthermore, the graphene oxide suspension of the present application includes graphene oxide and water. Optionally, the graphene oxide suspension further includes an additive.

[0077] Preferably, the graphene oxide suspension is composed of graphene oxide and water with a conductivity ≤ 20 μS / m. The water with a conductivity ≤ 20 μS / m in the present application, for example, is deionized water. Deionized water refers to pure water from which impurities in ionic form have been removed and has a pH of 7. The process of preparing the graphene oxide suspension in the present application does not require the addition of extra chemicals. Compared with the related technical solutions that require the addition of a small amount of additives, the preparation method of the present application is simpler and more environmentally friendly.

[0078] If the concentration of graphene oxide is too low, the time required for electro-depositing a reduced graphene oxide film with the required thickness is too long, resulting in excessive power consumption. If the concentration of graphene oxide is too high, it is not conducive to the dispersion of graphene oxide, making it difficult to prepare a uniformly dispersed graphene oxide suspension. Preferably, the concentration of graphene oxide in the graphene oxide suspension is 1 mg / mL to 5 mg / mL, including any value within this concentration range, for example, 1 mg / mL, 3 mg / mL, or 5 mg / mL.

[0079] Furthermore, before the step of electro-depositing on the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body and forming cuprous oxide generated by in-situ reaction between the copper current collector body and the reduced graphene oxide film, the preparation method of the current collector further includes:

[0080] Cut the copper current collector body into an area of a × b with the unit of cm 2 , immerse the copper current collector body in the first cleaning liquid and perform ultrasonic cleaning; immerse the copper current collector body in an acid solution to remove the oxide layer on the surface of the copper current collector body;

[0081] Cut the counter electrode into an area of c × d with the unit of cm 2 , and sequentially immerse it in the second cleaning liquid and perform ultrasonic cleaning; wherein, 0 < a ≤ 100 cm, 0 < b ≤ 10 cm; 0 < c ≤ 110 cm, 0 < d ≤ 15 cm; and 0.01 cm ≤ (c - a) ≤ 10 cm, 0.01 cm ≤ (d - b) ≤ 5 cm;

[0082] The steps of electrodepositing a copper current collector substrate disposed in a graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector substrate, and forming cuprous oxide generated through an in-situ reaction between the copper current collector substrate and the reduced graphene oxide film, include:

[0083] Using an electrochemical workstation, with the copper current collector as the working electrode, the counter electrode, reference electrode, and working electrode were placed in a graphene oxide suspension, and electrodeposition was performed using a chronoamperometry method.

[0084] The term "chronoamperometry" refers to an electrochemical method in which a single or double potential step is applied to the working electrode of an electrochemical system, and the current response is measured as a function of time.

[0085] Optionally, the copper current collector body in this application can be a copper foil, which is either brass or copper, and has a thickness of 0.01 mm to 1 mm, including any value within this thickness range, such as 0.01 mm, 0.1 mm, 0.5 mm, or 1 mm.

[0086] The counter electrode (CE), also known as the auxiliary electrode, forms a circuit with the working electrode, ensuring the smooth flow of current to the working electrode and guaranteeing that the studied reaction occurs on the working electrode. Compared to the working electrode, the counter electrode should have a larger surface area. In this application, the surface areas of the counter electrode and the working electrode satisfy the following relationship: 0.01 cm ≤ (ca) ≤ 10 cm, 0.01 cm ≤ (db) ≤ 5 cm, ensuring that the applied polarization voltage acts on the entire working electrode, which is beneficial for depositing a uniformly distributed reduced graphene oxide film. The counter electrode can be a stainless steel mesh, but the material is not limited to stainless steel, and the structure is not limited to a mesh structure. The reference electrode can be a saturated calomel electrode or an Ag / AgCl electrode, both of which are suitable for electrodeposition in neutral systems.

[0087] This application uses a first cleaning liquid to ultrasonically clean the copper current collector body to remove oil and impurities from its surface, thus preventing these impurities from affecting the uniformity of the reduced graphene oxide film and cuprous oxide. This application also uses a second cleaning liquid to ultrasonically clean the counter electrode to remove oil and impurities from its surface, preventing these impurities from interfering with the deposition of the reduced graphene oxide film.

[0088] Optionally, the first cleaning liquid and the second cleaning liquid can be one liquid or a combination of one or more liquids. For example, the first cleaning liquid and the second cleaning liquid are a combination of deionized water and an organic solvent, where the organic solvent can be anhydrous ethanol. More specifically, both the first cleaning liquid and the second cleaning liquid include anhydrous ethanol and deionized water, with the copper current collector body sequentially immersed in anhydrous ethanol and deionized water for cleaning, and the counter electrode sequentially immersed in anhydrous ethanol and deionized water for cleaning.

[0089] Furthermore, the cleaning process of the copper current collector also removes the oxide layer on the surface of the copper current collector, preventing the oxide layer from occupying the surface of the copper current collector and causing cuprous oxide to fail to form or to be unevenly distributed. For example, the acid used to remove the oxide layer can be hydrochloric acid.

[0090] Furthermore, in the step of electrodepositing a copper current collector body disposed in a graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming cuprous oxide generated by in-situ reaction between the copper current collector body and the reduced graphene oxide film, the electrodeposition voltage range is 0.01 V to 10 V, including any value within this voltage range, such as 0.01 V, 1 V, 5 V or 10 V; the electrodeposition time is 10 s to 3600 s, including any value within this time range, such as 10 s, 100 s, 1000 s, 2000 s, 3000 s or 3600 s.

[0091] Different applications of batteries have different requirements for the thickness of reduced graphene oxide films. The immersion method cannot accurately control the thickness of the reduced graphene oxide film. This application precisely controls the thickness of the reduced graphene oxide film from 1 μm to 20 μm by adjusting the voltage and time of electrodeposition, thereby meeting the needs of different application scenarios.

[0092] Furthermore, after electrodepositing a copper current collector body disposed in a graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming cuprous oxide generated through an in-situ reaction between the copper current collector body and the reduced graphene oxide film, the preparation method of the current collector further includes:

[0093] The electrodeposited copper current collector body is placed in a vacuum environment and dried at a temperature of 55℃~65℃ to obtain the current collector.

[0094] Cuprous oxide readily reacts with oxygen in humid environments, leading to its oxidation and degradation. Therefore, drying in a vacuum environment prevents this reaction. Furthermore, a drying temperature of 55°C to 65°C, or any value within this range (e.g., 55°C, 60°C, or 65°C), is chosen to avoid both excessively low temperatures and prolonged drying times, and excessively high temperatures that could accelerate the reaction rate and cause the cuprous oxide to react during drying.

[0095] Thirdly, embodiments of this application provide a negative electrode sheet, which has a current collector as described in the first aspect or a current collector prepared by the current collector preparation method described in the second aspect, and a negative electrode active material layer loaded on the surface of the current collector; the negative electrode active material layer is a lithium metal layer.

[0096] Fourthly, embodiments of this application provide a lithium metal battery, including a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive and negative electrode to form a battery cell. The electrolyte is injected into the battery cell.

[0097] The negative electrode sheet has a current collector prepared by the current collector preparation method described in the first aspect or the current collector preparation method described in the second aspect, and a negative electrode active material layer loaded on the surface of the current collector; the negative electrode active material layer is a lithium metal layer.

[0098] The technical solution of the present invention will now be described in conjunction with the embodiments and accompanying drawings.

[0099] Example 1

[0100] See Figure 2 The preparation method of this current collector includes the following steps:

[0101] S1. Preparation of graphene oxide suspension: Graphene oxide was prepared by freeze-drying using graphite as raw material and a modified Hummers method. 50 mg of graphene oxide was weighed and slowly added to 50 mL of deionized water. The mixture was magnetically stirred for 20 min and ultrasonically treated for 20 min. This process was repeated three times to obtain a uniformly dispersed graphene oxide suspension of 1 mg / mL.

[0102] S2. Pretreatment of the working electrode: Cut out a 3 cm × 4 cm copper foil, and immerse it in anhydrous ethanol and deionized water for ultrasonic cleaning 5 times each, 5 minutes each time, to remove surface oil and impurities. Then immerse the copper foil in a 1 M hydrochloric acid solution to remove the surface oxide layer, and rinse it with deionized water.

[0103] S3. Pretreatment of electrodes: Cut stainless steel mesh into 4 cm × 5 cm pieces, and immerse them in anhydrous ethanol and deionized water for ultrasonic cleaning 5 times each, 5 min each time.

[0104] S4. Place the copper current collector in a graphene oxide suspension and electrodeposit the copper current collector to obtain a reduced graphene oxide film. Simultaneously, the copper current collector reacts in situ with the graphene oxide to form cuprous oxide between the copper current collector and the reduced graphene oxide film. Use the treated copper foil as the working electrode, the stainless steel mesh as the counter electrode, and the saturated calomel electrode as the reference electrode. Immerse the three electrodes in the above 1 mg / mL graphene oxide suspension and anodize the copper foil using a chronoamperometry method, controlling the initial voltage to be 1 V and the time to be 300 s.

[0105] S5. Drying: Then transfer it to a vacuum oven at 60℃ to dry, and the current collector prepared by electrodeposition method can be obtained. At this time, the thickness of the reduced graphene oxide film is 8 μm.

[0106] Example 2

[0107] The method for preparing the current collector provided in this embodiment includes the following steps:

[0108] S1. Preparation of graphene oxide suspension: Graphene oxide was prepared by freeze-drying using graphite as raw material via a modified Hummers method. 100 mg of graphene oxide was weighed and slowly added to 50 mL of deionized water. The mixture was magnetically stirred for 20 min and ultrasonically treated for 20 min. This process was repeated three times to obtain a uniformly dispersed graphene oxide suspension of 2 mg / mL.

[0109] S2. Pretreatment of the working electrode: Cut out a 3 cm × 4 cm copper foil, and immerse it in anhydrous ethanol and deionized water for ultrasonic cleaning 5 times each, 5 minutes each time, to remove surface oil and impurities. Then, quickly immerse it in a 1 M hydrochloric acid solution to remove the surface oxide layer, and rinse it with deionized water.

[0110] S3. Pretreatment of electrodes: Cut stainless steel mesh into 4 cm × 5 cm pieces, and immerse them in anhydrous ethanol and deionized water for ultrasonic cleaning 5 times each, 5 min each time.

[0111] S4. Place the copper current collector in a graphene oxide suspension and electrodeposit the copper current collector to obtain a reduced graphene oxide film. Simultaneously, the copper current collector reacts in situ with the graphene oxide to form cuprous oxide between the copper current collector and the reduced graphene oxide film. Use the treated copper foil as the working electrode, the stainless steel mesh as the counter electrode, and the saturated calomel electrode as the reference electrode. Immerse the three electrodes in the above 2 mg / mL graphene oxide suspension and anodize the copper foil using a chronoamperometry method, controlling the initial voltage to be 5 V and the time to be 50 s.

[0112] S5. Drying: Then transfer it to an oven at 60℃ to dry, and the current collector prepared by electrodeposition method can be obtained. At this time, the thickness of the reduced graphene oxide film is 5 μm.

[0113] Example 3

[0114] The method for preparing the current collector provided in this embodiment includes the following steps:

[0115] S1. Preparation of graphene oxide suspension: Graphene oxide was prepared by freeze-drying using a modified Hummers method with graphite as the raw material. 250 mg of graphene oxide was weighed and slowly added to 50 mL of deionized water. The mixture was magnetically stirred for 20 min and ultrasonically treated for 20 min. This process was repeated three times to obtain a uniformly dispersed graphene oxide suspension of 5 mg / mL.

[0116] S2. Pretreatment of the working electrode: Cut out a 3 cm × 4 cm copper foil, and immerse it in anhydrous ethanol and deionized water for ultrasonic cleaning 5 times each, 5 minutes each time, to remove surface oil and impurities. Then, quickly immerse it in a 1M hydrochloric acid solution to remove the surface oxide layer, and rinse it with deionized water.

[0117] S3. Pretreatment of electrodes: Cut stainless steel mesh into 4 cm × 5 cm pieces, and immerse them in anhydrous ethanol and deionized water for ultrasonic cleaning 5 times each, 5 min each time.

[0118] S4. Place the copper current collector in a graphene oxide suspension and electrodeposit the copper current collector to obtain a reduced graphene oxide film. Simultaneously, the copper current collector reacts in situ with the graphene oxide to form cuprous oxide between the copper current collector and the reduced graphene oxide film. Use the treated copper foil as the working electrode, the stainless steel mesh as the counter electrode, and the saturated calomel electrode as the reference electrode. Immerse the three electrodes in the above 5 mg / mL graphene oxide suspension and anodize the copper foil using a chronoamperometry method, controlling the initial voltage to be 5 V and the time to be 10 s.

[0119] S5. Drying: Then transfer it to an oven at 60℃ to dry, and the current collector prepared by electrodeposition method can be obtained. At this time, the thickness of the reduced graphene oxide film is 2 μm.

[0120] Example 4

[0121] The only difference between this embodiment and Embodiment 1 is that in step S4, the initial voltage is controlled to be 0.01 V and the time is 60 s, and the thickness of the final reduced graphene oxide film is 0.2 μm (less than 1 μm).

[0122] Example 5

[0123] The only difference between this embodiment and Embodiment 1 is that in step S4, the initial voltage is controlled to be 10 V and the time is 1800 s, and the thickness of the final reduced graphene oxide film is 34 μm (greater than 20 μm).

[0124] Example 6

[0125] The only difference between this embodiment and Example 1 is that in step S1, the concentration of graphene oxide in the prepared graphene oxide suspension is 0.1 mg / mL, and the thickness of the final reduced graphene oxide film is 0.4 μm.

[0126] Example 7

[0127] The only difference between this embodiment and Example 1 is that in step S1, the concentration of graphene oxide in the prepared graphene oxide suspension is 10 mg / mL, and the thickness of the final reduced graphene oxide film is 28 μm.

[0128] Comparative Example 1

[0129] The preparation method of the current collector provided in this comparative example includes the following steps:

[0130] Step 1: Using graphite as raw material, graphene oxide was prepared by freeze-drying using a modified Hummers method. 100 mg of graphene oxide was weighed and slowly added to 50 mL of deionized water. The mixture was magnetically stirred for 20 min and ultrasonically treated for 20 min. This process was repeated three times to obtain a uniformly dispersed 2 mg / mL graphene oxide suspension.

[0131] Step 2: Cut out 3 cm × 4 cm copper foil, and immerse it in anhydrous ethanol and deionized water in sequence for ultrasonic cleaning 5 times, 5 minutes each time, to remove surface oil and impurities. Then, quickly immerse it in 1 M hydrochloric acid solution to remove the surface oxide layer, and rinse it clean with deionized water.

[0132] Step 3: Immerse the treated copper foil in a uniformly dispersed 2 mg / mL graphene oxide suspension and dry it in an oven at 60°C to obtain the current collector prepared by the immersion method.

[0133] The final thickness of the reduced graphene oxide film was 15 μm.

[0134] Comparative Example 2

[0135] The preparation method of the current collector provided in this comparative example includes the following steps:

[0136] Step 1: Using graphite as raw material, graphene oxide was prepared by freeze-drying using a modified Hummers method. 100 mg of graphene oxide was weighed and slowly added to 50 mL of deionized water. The mixture was magnetically stirred for 20 min and ultrasonically treated for 20 min. This process was repeated three times to obtain a uniformly dispersed 1 mg / mL graphene oxide suspension. The pH of the solution was then adjusted to 3 using hydrochloric acid.

[0137] Step 2: Cut out 3 cm × 4 cm copper foil, and immerse it in anhydrous ethanol and deionized water in sequence for ultrasonic cleaning 5 times, 5 minutes each time, to remove surface oil and impurities. Then, quickly immerse it in 1 M hydrochloric acid solution to remove the surface oxide layer, and rinse it clean with deionized water.

[0138] Step 3: The processed copper foil is used as the working electrode, a 4 cm × 5 cm stainless steel mesh is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode. The three electrodes are immersed in the above-mentioned graphene oxide suspension with pH=3. The chronoamperometry method is used to control the initial voltage at 2 V and the time at 40 s. Then, the electrodes are dried in an oven at 60 ℃ to obtain the current collector prepared by electrodeposition under acidic conditions.

[0139] The final thickness of the reduced graphene oxide film was 8 μm.

[0140] Comparative Example 3

[0141] The only difference between this comparative example and Example 1 is that in step S4, the pH of the graphene oxide solution is 10, and the final thickness of the reduced graphene oxide film is 9 μm. The hydroxide ions (OH-) in the alkaline solution... - At higher concentrations, these substances possess strong reducing properties and may react with graphene oxide, leading to its reduction or other alterations. This reaction causes differences in graphene oxide concentration across different regions of the solution, creating a concentration gradient. During electrodeposition, this results in an uneven distribution of the reduced graphene oxide film on the surface of the copper current collector.

[0142] Material characterization

[0143] (1) Photograph-based material characterization:

[0144] See Figure 3 , Figure 3 This is a photograph of a current collector according to Example 1. Figure 3 The matte black area represents a reduced graphene oxide film. Figure 3 As can be seen, the reduced graphene oxide film formed by electrodeposition is evenly distributed on the surface of the copper current collector, and there are no obvious unevenness, cracks, wrinkles, gaps and peeling on the black matte area.

[0145] See Figure 4 , Figure 4 This is a photograph of a current collector, as shown in Comparative Example 1. Figure 4 The black area in the middle is a reduced graphene oxide film, from Figure 4 It is evident that the reduced graphene oxide film prepared by the immersion method exhibits numerous wrinkles, detachments, and cracks. Possible reasons include: Firstly, the reduced graphene oxide film prepared by the immersion method lacks interaction forces with the copper foil, resulting in insufficient bonding and easy detachment and cracking. Secondly, the reduced graphene oxide film prepared by the immersion method is not uniformly distributed, exhibiting significant thickness variations. Thicker sections are prone to separation from the copper foil, leading to issues such as wrinkles, detachment, and cracking. Figure 4 The wrinkles and delamination shown.

[0146] (2) Material characterization based on scanning electron microscopy images:

[0147] See Figure 5 , Figure 5 This is a scanning electron microscope (SEM) image of a current collector in Example 1. The SEM scale bar is 5 μm. Even at the microscopic scale, the electrodeposited reduced graphene oxide film is very uniformly distributed on the surface of the copper current collector, without obvious cracks, wrinkles, or peeling.

[0148] See Figure 6 , Figure 6 Example 1: Deposition of 5 mAh cm⁻¹ on a current collector -2 Scanning electron microscope image of lithium. Figure 6 The absence of obvious strip-shaped or block-shaped substances indicates that metallic lithium is uniformly and densely distributed on the surface of the current collector. This is because the cuprous oxide and reduced graphene oxide films have uniform current density in the planar direction, thereby inducing lithium metal to be deposited in a planar manner on its surface.

[0149] See Figure 7 , Figure 7 5 mAh cm⁻¹ was deposited on a current collector in Comparative Example 1. -2 A scanning electron microscope image of lithium. From Figure 7As can be seen, a large number of intertwined lithium dendrites are present on the surface of the current collector, appearing as strips or blocks in the figure, forming a loose and porous lithium deposition morphology. This indicates that the reduced graphene oxide film prepared by the immersion method is not uniformly distributed, and the conductivity and lithium affinity of the electrode are unevenly distributed, which makes it easy to form lithium dendrites and volume expansion, leading to structural collapse during cycling, thus making the cycle stability of the battery worse.

[0150] See Figure 8 , Figure 8 This is a scanning electron microscope image of a current collector, Comparative Example 3. Figure 8 The electrode has a large number of wrinkles, which can easily induce uneven distribution of local current density on the electrode surface during cycling, ultimately deteriorating the battery's cycle performance.

[0151] (3) Material characterization based on XRD patterns:

[0152] See Figure 9 , Figure 9 This is the XRD (X-ray diffraction) pattern of a current collector in Example 1. From... Figure 9 It can be seen that, in addition to the diffraction peaks of copper, there are also diffraction peaks of cuprous oxide, proving that cuprous oxide was formed in situ during the electrodeposition process.

[0153] See Figure 10 , Figure 10 This is the XRD pattern of a current collector in Comparative Example 2; from Figure 10 As can be seen, there are diffraction peaks for copper and carbon, but no diffraction peak for cuprous oxide, proving that cuprous oxide, which serves as a lithiophilic site, was not formed during electrodeposition under acidic conditions of pH=3.

[0154] (4) Material characterization based on EDS-mapping images:

[0155] See Figures 11 to 14 ,in, Figure 11 This is a selected area map of an EDS-mapping (energy dispersive spectroscopy-area scanning) current collector according to Example 1. A certain area of ​​the sample is selected, and an electron beam is moved back and forth across the sample surface for scanning. Each time characteristic X-ray photons are collected at a point, a bright spot is projected at the corresponding location in the image. These bright spots represent the mapping of elements.

[0156] Figure 12 yes Figure 11 EDS-mapping image of C element in the corresponding range. Figure 12 The multiple gray-white bright spots representing C elements are evenly distributed, indicating that C elements are evenly distributed on the current collector, and that C elements exist in the reduced graphene oxide film, that is, the reduced graphene oxide film is evenly distributed.

[0157] Figure 13yes Figure 11 EDS-mapping image of the O element in the corresponding range. Figure 13 The multiple gray-white bright spots representing the element O are evenly distributed, indicating that the element O is evenly distributed on the current collector, and that the element O exists in cuprous oxide, that is, cuprous oxide is evenly distributed.

[0158] Figure 14 yes Figure 11 EDS-mapping image of Cu element in the corresponding range Figure 14 The image shows multiple grayish-white bright spots of Cu, indicating a uniform distribution of Cu on the surface of the current collector. Figure 13 Analysis showed that cuprous oxide, acting as a lithiophilic site, was uniformly dispersed on the surface of the current collector.

[0159] Performance testing

[0160] Half-cells were fabricated using the current collectors prepared in Examples 1-7 and Comparative Examples 1-3, respectively. The specific steps are as follows: All battery assembly processes were completed in a glove box under an argon atmosphere, with water and oxygen content both less than 0.1 ppm. The prepared current collector was used as the working electrode, i.e., the positive electrode; Celgard 2400 PP was used as the separator; lithium sheets were used as the counter electrode, i.e., the negative electrode; an ether-based electrolyte (1 M lithium bis(trifluoromethanesulfonyl)imide dissolved in a 1:1 volume ratio of 1,3-dioxolane and ethylene glycol dimethyl ether) was used, with 2 wt% LiNO3 additive added to the ether-based electrolyte; a CR2032 battery case was used as the battery case; and the coin cell was assembled in the following order: positive electrode case, current collector, electrolyte, separator, lithium sheet, gasket, spring, and negative electrode case. After encapsulation, the battery was allowed to stand at room temperature for 8 hours to ensure complete electrolyte wetting of the electrodes before testing.

[0161] The average coulombic efficiency of each CR2032 coin cell was tested, and the test results are shown in Table 1.

[0162] Table 1: Average coulombic efficiency test results of half-cells fabricated with current collectors in Examples 1-7 and Comparative Examples 1-3

[0163]

[0164] Referring to Table 1, Example 1 was performed at a current density of 1 mA cm⁻¹. -2 Cyclic capacity is 1 mAh cm⁻¹ -2Under the given cycling conditions, the battery can stably cycle for 200 cycles with an average coulombic efficiency of 97.5%, demonstrating excellent cycle stability. Example 2 can stably cycle for 340 cycles with an average coulombic efficiency of 98.8%. Example 3 can stably cycle for 170 cycles with an average coulombic efficiency of 97.5%. This reflects that the present application, by forming cuprous oxide, which acts as a lithiophilic site, induces uniform lithium nucleation through uniformly distributed lithiophilic sites, thereby suppressing lithium dendrite growth and significantly improving the coulombic efficiency of the battery.

[0165] Example 4: Because the reduced graphene oxide film is thin, it cannot effectively and uniformly distribute the current density on the electrode surface during battery cycling. At the electron concentration point, a large amount of lithium ions will be induced to deposit and form lithium dendrites. As lithium dendrites grow and dead lithium forms, active lithium and electrolyte are continuously consumed, causing battery performance to deteriorate. The average coulombic efficiency of the battery after 75 cycles is 93.4%.

[0166] In Example 5, due to the large thickness of the reduced graphene oxide film, the electron transport rate is much higher than the ion transport rate during lithium-ion deposition. Therefore, the ion transport rate is the rate-determining step during deposition. When the reduced graphene oxide thickness on the copper current collector surface is large, it severely hinders lithium-ion transport, thereby reducing the reaction kinetics inside the battery. The slow kinetics result in an average coulombic efficiency of only 85.7% after 45 cycles.

[0167] In Example 6, due to the low concentration of graphene oxide in the graphene oxide suspension, the electrodeposited reduced graphene oxide film was relatively thin. Similarly, during battery cycling, the current density on the electrode surface could not be effectively and uniformly dispersed, leading to the induction of large-scale lithium ion deposition and the formation of lithium dendrites at electron concentration points. As lithium dendrites grew and dead lithium formed, active lithium and electrolyte were continuously consumed, causing battery performance deterioration. The average coulombic efficiency after 90 cycles was only 93.6%.

[0168] In Example 7, due to the excessively high concentration of graphene oxide in the graphene oxide suspension, the electrodeposited reduced graphene oxide film tended to be too thick. A large thickness of reduced graphene oxide severely hindered lithium-ion transport, thereby reducing the internal reaction kinetics of the battery, resulting in an average coulombic efficiency of 96.4% after 120 cycles in Example 7.

[0169] In Comparative Example 1, the copper current collector was functionalized using graphene oxide via an immersion method. However, the current collector prepared by this method has difficulty ensuring the uniformity of the reduced graphene oxide layer. The poor bonding between the reduced graphene oxide layer and the copper current collector results in the detachment of the reduced graphene oxide layer, leading to poor conductivity uniformity and uneven distribution of lithium-affinity sites on the electrode. This makes it easy for lithium dendrites to form and for volume expansion to occur, causing structural collapse during cycling. Consequently, the cycle stability of the battery deteriorates, resulting in an average coulombic efficiency of 94.5% for Comparative Example 1 after 100 cycles.

[0170] In Comparative Example 2, due to electrodeposition in an acidic environment, cuprous oxide is easily disproportionated to divalent copper, resulting in cuprous oxide not being retained on the copper current collector. Compared with Example 1, Comparative Example 2 lacks cuprous oxide as a lithiophilic site, making it difficult to effectively suppress lithium dendrite growth and resulting in a lack of improvement in coulombic efficiency. Consequently, the average coulombic efficiency of the battery after 110 cycles was 96.8%.

[0171] Comparative Example 3, due to electrodeposition in an alkaline environment, resulted in a large number of wrinkles in the prepared reduced graphene oxide film. During cycling, this easily induced uneven distribution of local current density on the electrode surface, ultimately deteriorating the battery's cycling performance. As a result, the average coulombic efficiency of the battery after 110 cycles was 94.3%.

[0172] The preparation method of a current collector disclosed in the embodiments of the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the preparation method of a current collector and its core idea. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a current collector, characterized in that, Includes the following steps: Electrodeposition is performed on a copper current collector body disposed in a graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and cuprous oxide is formed between the copper current collector body and the reduced graphene oxide film through an in-situ reaction; wherein the pH of the graphene oxide suspension is 6.5~7.

1.

2. The method for preparing a current collector according to claim 1, characterized in that, The reduced graphene oxide film has cuprous oxide generated through an in-situ reaction.

3. The method for preparing a current collector according to claim 1, characterized in that, The graphene oxide suspension is composed of graphene oxide and water with an electrical conductivity ≤20 μS / m. And / or, the concentration of graphene oxide in the graphene oxide suspension is 1 mg / mL to 5 mg / mL.

4. The method for preparing a current collector according to claim 1, characterized in that, Before the step of electrodepositing the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming cuprous oxide generated through an in-situ reaction between the copper current collector body and the reduced graphene oxide film, the preparation method of the current collector further includes: The copper current collector body is cut into a piece with an area of ​​a×b, where the unit is cm. 2 The copper current collector body is immersed in a first cleaning liquid for ultrasonic cleaning; the copper current collector body is immersed in an acid solution to remove the oxide layer on the surface of the copper current collector body. The counter electrode is cut into an area of c×d with the unit of cm 2 , and the counter electrode is immersed in the second cleaning liquid for ultrasonic cleaning; where 0 < a ≤ 100 cm, 0 < b ≤ 10 cm; 0 < c ≤ 110 cm, 0 < d ≤ 15 cm; and 0.01 cm ≤ (c - a) ≤ 10 cm, 0.01 cm ≤ (d - b) ≤ 5 cm; The step of electrodepositing the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming cuprous oxide generated through an in-situ reaction between the copper current collector body and the reduced graphene oxide film, includes: Using an electrochemical workstation, with the copper current collector as the working electrode, the counter electrode, reference electrode, and working electrode are placed in the graphene oxide suspension, and electrodeposition is performed using a chronoamperometry method.

5. The method for preparing a current collector according to any one of claims 1 to 4, characterized in that, In the step of electrodepositing the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming cuprous oxide generated by in-situ reaction between the copper current collector body and the reduced graphene oxide film, the electrodeposition voltage range is 0.01 V to 10 V, and the electrodeposition time is 10 s to 3600 s. And / or, after the step of electrodepositing the copper current collector body disposed in the graphene oxide suspension to deposit a reduced graphene oxide film on the copper current collector body, and forming cuprous oxide generated by in-situ reaction between the copper current collector body and the reduced graphene oxide film, the method for preparing the current collector further includes: The copper current collector body after electrodeposition is placed in a vacuum environment and dried at a temperature of 55°C to 65°C to obtain the current collector.

6. The method for preparing a current collector according to any one of claims 1 to 4, characterized in that, Some of the cuprous oxide is distributed on the side of the reduced graphene oxide film away from the copper current collector body and within the reduced graphene oxide film.

7. The method for preparing a current collector according to any one of claims 1 to 4, characterized in that, The conductivity of the copper current collector body is x in S / m, and the conductivity of the reduced graphene oxide film is y in S / m; wherein, 5.5 × 10 7 S / m≤x≤6×10 7 S / m, 7×10 3 S / m≤y≤30×10 3 S / m, x / y≥10 3 ; And / or, the thickness of the reduced graphene oxide film is 1 μm to 20 μm.

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