Method for preparing high-conductivity lithium battery copper foil through hydroxylation modified graphene co-deposition

Abstract

The invention discloses a method for preparing a high-conductivity lithium battery copper foil through hydroxylation modified graphene co-deposition, which comprises the following steps: S1, synthesizing graphene oxide by adopting an improved Hummers method: in an ice bath, adding natural graphite and NaNO3 into a mixed acid of concentrated sulfuric acid and phosphoric acid, and stirring for 1 hour to fully disperse the graphite; adding KMnO4 in three times, continuously stirring for 20 minutes, removing the ice bath, heating the reaction system to 50 DEG C, continuously stirring for 24 hours until the solution gradually becomes a brownish black viscous material, adding 30% H2O2 until the color of the solution becomes bright yellow from brownish black, washing the product with a 5% HCl solution for three times, and washing with deionized water until the product is neutral for later use. Graphene subjected to hydroxylation treatment is introduced in the preparation process of the electrolytic copper foil, and copper and functionalized graphene are synchronously deposited on the surface of a cathode by utilizing an electrochemical co-deposition technology, so that the copper foil for the lithium ion battery with high conductivity, high mechanical strength and good interface stability is obtained.

Description

Technical Field

[0001] This invention relates to the field of copper foil electroplating technology, and in particular to a method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene. Background Technology

[0002] Copper foil is one of the key basic materials for lithium-ion batteries, mainly used as a negative electrode current collector. In the battery, it not only carries the negative electrode active material but also collects electrons generated by the negative electrode active material (such as graphite and silicon carbon) and conducts them to the external circuit through the electrode tabs. Therefore, its internal resistance needs to be as low as possible. Excessive internal resistance has the following drawbacks: it causes the voltage under load to drop rapidly, making the battery unable to provide sufficient power; excessive internal resistance causes the battery terminal voltage to reach the charging cutoff voltage more quickly, causing the BMS (Battery Management System) to reduce the charging current prematurely, thus prolonging the charging time and preventing true "fast charging"; excessive internal resistance causes the high-resistance cell to heat up violently during high-current charging and discharging, affecting battery safety.

[0003] Lithium-ion battery copper foil is currently prepared using an electrodeposition process. The purity of the copper foil is greater than 98.5%, and its resistance is close to the theoretical resistance of copper. There is not much room for improvement in resistance by increasing the purity.

[0004] Graphene is one of the best-known conductive materials (its electron mobility is far higher than that of copper). Forming a graphene conductive network on the surface of copper foil can provide a "highway" for electrons, reducing ohmic resistance. Traditional copper foil has a smooth surface, limiting the contact area with the negative electrode active material (such as graphite particles). Graphene, with its huge specific surface area and unique two-dimensional structure, can be coated onto copper foil to increase surface roughness and active sites, thereby reducing contact resistance.

[0005] To address these issues, we propose a method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene includes the following steps: S1. Synthesis of graphene oxide using the modified Hummers method: Under ice bath conditions, natural graphite and NaNO3 were added to a mixture of concentrated sulfuric acid and phosphoric acid, and stirred for 1 hour to ensure full dispersion of graphite. KMnO4 was added in three portions, and stirring was continued for 20 minutes. The ice bath was removed, and the reaction system was heated to 50°C and stirred continuously for 24 hours. The solution gradually turned into a brownish-black viscous substance. Then, 30% H2O2 was added, and the solution color changed from brownish-black to bright yellow. The product was washed three times with 5% HCl solution and then washed with deionized water until neutral for later use. S2. Copper foil electrolyte preparation: It is composed of a basic electrolyte and additives; The basic electrolyte consists of CuSO4·5H2O and H2SO4; additives include chloride ions, sodium polydithiopropane sulfonate, collagen, and polyethylene glycol. S3. Dispersion of modified graphene in electrolyte: Slowly add the graphene dispersion to the electrolyte to make the mass concentration of graphene 5%, and stir with air. During use, the electrolyte should be kept at a flow rate of 52-55 m3 / h to prevent graphene from settling. S4. Finally, use a foil-making machine to produce foil.

[0008] Furthermore, in step S1, the mass ratio of natural graphite to NaNO3 is 2:1.

[0009] Furthermore, in step S1, the volume ratio of concentrated sulfuric acid to phosphoric acid is 12:1.

[0010] Furthermore, in step S2, the concentrations of each component in the basic electrolyte are CuSO4·5H2O: 90 g / L and H2SO4: 110 g / L; the concentrations of each component in the additives are chloride ions: 25 mg / L, sodium polydisulfide dipropane sulfonate: 12 mg / L, collagen: 8 mg / L, and polyethylene glycol: 0.5 mg / L.

[0011] Furthermore, in step S4, the current density of the cathode roller of the foil-making machine is 6500 A / m. 2 Copper foil was prepared with a linear velocity of 12 m / min.

[0012] Compared with the prior art, the beneficial effects of the present invention are: This invention introduces hydroxylated graphene into the electrolytic copper foil preparation process and uses electrochemical co-deposition technology to simultaneously deposit copper and functionalized graphene on the cathode surface, thereby obtaining a copper foil for lithium-ion batteries that has both high conductivity, high mechanical strength and good interfacial stability. Attached Figure Description

[0013] Figure 1 These are SEM images of the products prepared in the comparative examples and Examples 1-3 of this invention. Detailed Implementation

[0014] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0015] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0016] 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.

[0017] A method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene is disclosed. By introducing hydroxylated graphene into the preparation process of electrolytic copper foil, copper and functionalized graphene are simultaneously deposited on the cathode surface using electrochemical co-deposition technology, thereby obtaining copper foil for lithium-ion batteries that has high conductivity, high mechanical strength and good interfacial stability.

[0018] Hydroxylated graphene (HO-G): By partially reducing graphene oxide (GO) or directly introducing hydroxyl functional groups, it is made to have good water dispersibility and certain conductivity, while retaining certain oxygen-containing functional groups to enhance the interaction with copper ions.

[0019] Co-deposition mechanism: In acidic sulfate electrolytes, Cu 2+ At the cathode, the graphene is reduced to metallic copper. Simultaneously, negatively charged hydroxylated graphene particles are driven by the electric field to migrate to the cathode surface and are "captured" by the newly formed copper grains and embedded in the copper matrix, forming a copper / graphene composite structure.

[0020] Performance improvements: Graphene networks enhance electron conduction pathways; Inhibit excessive growth of copper grains, refine grains, and improve density; Enhance the interfacial bonding between copper foil and negative electrode active materials (such as silicon carbide and graphite).

[0021] Specifically as follows: I. Preparation of Hydroxylated Graphene Graphene oxide (GO) was synthesized using a modified Hummers process. The specific process is as follows: Under ice bath conditions, 1 g of natural graphite and 0.5 g of NaNO3 were added to 50 mL of a mixture of concentrated sulfuric acid and phosphoric acid (volume ratio 12:1), and stirred for 1 hour to ensure complete dispersion of the graphite. Then, 6 g of KMnO4 was added in three portions, with stirring continued for 20 minutes after each addition. The ice bath was removed, and the reaction mixture was heated to 50°C and stirred continuously for 24 hours, during which the solution gradually turned into a brownish-black viscous substance. Then, 15 mL of 30% H2O2 was added, and the solution color changed from brownish-black to bright yellow. The product was washed three times with 5% HCl solution, and then washed with deionized water until neutral before use.

[0022] II. Preparation of Copper Foil Electrolyte Basic electrolyte composition: CuSO4·5H2O (90 g / L), H2SO4 (110 g / L), additives: chloride ions (25 mg / L), sodium polydithiopropane sulfonate (12 mg / L), collagen (8 mg / L), polyethylene glycol (0.5 mg / L).

[0023] Dispersion of modified graphene in electrolyte Slowly add the graphene dispersion to the electrolyte to achieve a graphene mass concentration of 5%. Pneumatic stirring is sufficient. During use, maintain the electrolyte concentration at 52-55 μm. 3 A flow rate of / h is used to prevent graphene from settling.

[0024] raw foil The cathode roller current density of the foil-making machine is 6500 A / m 2 A linear velocity of 12 m / min was used to prepare an 8 μm thick copper foil.

[0025] Please see Figure 1 Example 1 A sample containing 3% graphene in the electrolyte was used to prepare a lithium-ion battery copper foil with a thickness of 8 μm, a resistance of 0.02 Ω, and a resistivity of 3.0 × 10⁻⁶. -8 Ω·m.

[0026] Example 2 A sample containing 5% graphene in the electrolyte was used to prepare a lithium-ion battery copper foil with a thickness of 8 μm, a resistance of 0.019 Ω, and a resistivity of 1.5 × 10⁻⁶. -8 Ω·m.

[0027] Example 3 A sample containing 10% graphene in the electrolyte was used to prepare a lithium-ion battery copper foil with a thickness of 8 μm, a resistance of 0.046 Ω, and a resistivity of 9.5 × 10⁻⁶. -8 Ω·m.

[0028] Comparative Example Lithium-ion battery copper foil was prepared using an electrolyte sample without graphene. The prepared lithium-ion battery copper foil had a thickness of 8 μm, a resistivity of 0.052 Ω, and a resistivity of 4.51 × 10⁻⁶. -7 Ω·m.

[0029] Table 1 compares proportions and Examples 1 through 3. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0030] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene, characterized in that: Includes the following steps: S1. Synthesis of graphene oxide using the modified Hummers method: Under ice bath conditions, natural graphite and NaNO3 were added to a mixture of concentrated sulfuric acid and phosphoric acid, and stirred for 1 hour to ensure full dispersion of graphite. KMnO4 was added in three portions, and stirring was continued for 20 minutes. The ice bath was removed, and the reaction system was heated to 50°C and stirred continuously for 24 hours. The solution gradually turned into a brownish-black viscous substance. Then, 30% H2O2 was added, and the solution color changed from brownish-black to bright yellow. The product was washed three times with 5% HCl solution and then washed with deionized water until neutral for later use. S2. Copper foil electrolyte preparation: It is composed of a basic electrolyte and additives; The basic electrolyte consists of CuSO4·5H2O and H2SO4; additives include chloride ions, sodium polydithiopropane sulfonate, collagen, and polyethylene glycol. S3. Dispersion of modified graphene in electrolyte: Slowly add the graphene dispersion to the electrolyte to achieve a graphene mass concentration of 5%, followed by pneumatic stirring. During use, maintain the electrolyte concentration at 52-55 μm. 3 A flow rate of / h is used to prevent graphene from settling. S4. Finally, use a foil-making machine to produce foil.

2. The method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene according to claim 1, characterized in that: In step S1, the mass ratio of natural graphite to NaNO3 is 2:

1.

3. The method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene according to claim 1, characterized in that: In step S1, the volume ratio of concentrated sulfuric acid to phosphoric acid is 12:

1.

4. The method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene according to claim 1, characterized in that: In step S2, the concentrations of each component in the basic electrolyte are CuSO4·5H2O: 90 g / L and H2SO4: 110 g / L; the concentrations of each component in the additives are chloride ions: 25 mg / L, sodium polydisulfide dipropane sulfonate: 12 mg / L, collagen: 8 mg / L, and polyethylene glycol: 0.5 mg / L.

5. The method for preparing highly conductive lithium-ion battery copper foil by co-deposition of hydroxylated modified graphene according to claim 1, characterized in that: In step S4, the cathode roller current density of the foil-making machine is 6500 A / m. 2 Copper foil was prepared with a linear velocity of 12 m / min.

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