Modified metal material and preparation method and application thereof

Abstract

The invention belongs to the technical field of metal ion batteries, and particularly relates to a modified metal material and a preparation method and application thereof. The method comprises the following steps: taking a metal material as a reduction substrate, soaking the metal material in a graphene oxide aqueous solution, standing at room temperature, driving graphene oxide to generate a reduction reaction on the surface of the metal material by utilizing a potential difference between metal and graphene oxide to form a graphene / metal composite structure, and drying to obtain the modified metal material. The process is simple, does not need heating, does not need a strong reducing agent, and is environment-friendly and energy-saving. In addition, the reduced graphene film on the surface of the metal material and the metal substrate have extremely high interface bonding strength. In addition, after the metal substrate of the modified metal material is removed, the self-supporting graphene film can be obtained, and the size of the graphene film can reach the meter level.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal ion batteries, and particularly relates to a modified metal material, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of renewable energy and electric vehicle industries, metal ion batteries with high energy density and long cycle life, such as lithium-ion batteries, sodium-ion batteries, and zinc-ion batteries, have become research hotspots. As the metal foil serving as the negative electrode current collector of the battery, its surface characteristics directly affect the deposition behavior of metal ions. There are usually problems such as microscopic defects, uneven grain boundary distribution, and oxide layers on the surface of commercial metal foils, resulting in local concentration of metal ion flux during the electrochemical deposition process and inducing uncontrollable growth of dendrites. Dendrites not only pierce the separator and cause thermal runaway, but also cause contact failure between the active material and the current collector, leading to a sharp decline in battery capacity, seriously restricting the cycle life and safety of the battery.

[0003] Traditional solutions mostly adopt three-dimensional porous current collectors or coat polymer coatings on the surface of metal foils. However, the pore structure significantly increases the volume energy density, and the low conductivity of the polymer coating increases the interfacial impedance, thereby reducing the capacity and performance of the battery.

[0004] Due to its ultra-high conductivity, mechanical strength, and two-dimensional confinement effect, graphene has been widely used in the fields of electrochemical storage and electrochemistry. Existing technologies utilize the defects contained in graphene as active sites to guide the initial nucleation of metal ions and reduce the overpotential, promoting the uniform deposition of metal ions, thereby significantly inhibiting the growth of metal dendrites. Document 1: Ge H, Tian H, Li M X, et al. Influence of reaction conditions on the reduction efficiency of functional groups on the surface of graphene oxide reduced by hydrazine hydrate [J]. Journal of Liaoning University (Natural Sciences Edition), 2014, 41 (3). In Document 1, hydrazine hydrate was used as a reducing agent to reduce graphene oxide, and the adsorption of ions on the surface of the copper foil was enhanced through functional group modification, thereby inhibiting the uneven deposition of lithium metal on the surface of the copper foil, reducing dendrite formation, and making the cycle more stable and the life extended.

[0005] Although the above-mentioned existing technologies show good sodium dendrite growth inhibition effect on the surface of metal foils after modifying them with graphene, the reduction process of graphene oxide usually relies on highly toxic chemical reducing agents or high-energy-consuming heat treatments, which not only increases the process complexity but also may lead to structural defects in graphene. Summary of the Invention

[0006] In order to solve the technical problem that the above-mentioned existing technologies usually rely on chemical reducing agents or high-energy-consuming heat treatments to modify metal foils with graphene, the present invention provides a modified metal material, its preparation method and application.

[0007] The present invention utilizes the potential difference between the metal and graphene oxide to drive the spontaneous redox reaction of graphene oxide at room temperature, realizing the effective reduction and uniform coverage of graphene on the surface of the metal material, obtaining a graphene-modified metal material, and avoiding the use of reducing agents or high-energy-consuming heat treatments to reduce graphene oxide during the process of modifying metal foils with graphene. Moreover, graphene oxide contains oxygen-containing groups such as carboxyl and hydroxyl groups, and these groups are partially removed during reduction to generate active sites that react with the oxides on the metal surface to form bonds such as M-O-C, where M is a metal, thereby enhancing the interfacial bonding strength between the metal and graphene and achieving the tight bonding of the metal material and graphene.

[0008] The first object of the present invention is to provide a preparation method of a modified metal material, comprising the following steps: Using the metal material as a reduction substrate, immersing the metal material in an aqueous solution of graphene oxide, standing at room temperature, and utilizing the potential difference between the metal and graphene oxide to drive the reduction reaction of graphene oxide on the surface of the metal material to form a graphene / metal composite structure. After drying, a modified metal material is obtained.

[0009] Preferably, the preparation method of the aqueous solution of graphene oxide is as follows: S1. Under ice-water bath conditions, add graphite powder and sodium nitrate to concentrated sulfuric acid, stir evenly, and add potassium permanganate in portions while controlling the temperature not exceeding 20°C; then, raise the temperature to 35°C and stir for 30 minutes to oxidize the graphite to graphite oxide, obtaining graphite oxide.

[0010] S2. Disperse the graphite oxide into deionized water and exfoliate the graphite oxide by ultrasonic oscillation to obtain an aqueous solution of graphene oxide.

[0011] Preferably, the concentration of the aqueous solution of graphene oxide is 0.1 mg / mL to 1 mg / mL.

[0012] Preferably, the standing time at room temperature is 2 h to 12 h.

[0013] Preferably, the metal material is aluminum, copper, zinc, iron, tin or nickel.

[0014] Preferably, the structural form of the metal material is a metal foil, a metal sheet, a porous metal, a metal foam or a metal nanowire filtration membrane.

[0015] Preferably, the form of immersion is one of single-sided immersion, double-sided immersion, horizontal immersion, vertical immersion, floating immersion and bottom immersion.

[0016] Before the metal material is immersed in the graphene oxide solution, the metal material is pretreated, and the specific method of pretreatment is as follows: The metal material is placed in a solvent, ultrasonically cleaned, and then placed in a first acid solution to remove contaminants and oxide layers on the surface of the metal material.

[0017] Preferably, the solvent is at least one of deionized water, acetone, ethanol and toluene.

[0018] Preferably, the first acid solution is dilute hydrochloric acid, dilute acetic acid or dilute nitric acid; the concentration of the first acid solution is 0.1 mol / L to 5 mol / L.

[0019] The immersed metal material is dried to form a uniform graphene film on the surface of the metal material, and a modified metal material is obtained.

[0020] Preferably, the drying conditions are freeze-drying at -5°C to -55°C for 1 h to 48 h; or drying at 30°C to 100°C for 1 h to 48 h.

[0021] The second object of the present invention is to provide a modified metal material prepared by the preparation method of the above-mentioned modified metal material.

[0022] The third object of the present invention is to provide the application of the above-mentioned modified metal material in the preparation of a metal battery, and the modified metal material is used as the negative electrode material of the metal battery.

[0023] Preferably, the metal battery includes but is not limited to a sodium metal battery, a zinc metal battery, a potassium metal battery and a lithium metal battery.

[0024] Preferably, the preparation method of the lithium metal battery is as follows: Using the modified metal material as the working electrode, the working electrode, the separator material, the electrolyte and the counter electrode are assembled in sequence to obtain a lithium metal battery.

[0025] Preferably, the counter electrode is a lithium foil.

[0026] Preferably, the electrolyte is lithium hexafluorophosphate.

[0027] Compared with the prior art, the present invention has the following technical effects: 1. The present invention utilizes the potential difference between metal and graphene oxide to drive the spontaneous redox reaction of graphene oxide at room temperature, achieving the effective reduction and uniform coverage of graphene oxide on the surface of metal materials, obtaining graphene-modified metal materials, and solving the technical problem of using a reducing agent or high-energy-consuming heat treatment to reduce graphene oxide during the modification of metal foils with graphene. Moreover, the oxygen-containing groups on the surface of reduced graphene form strong interfacial bonding with the metal surface through chemical bonding, realizing the tight combination of metal materials and graphene.

[0028] 2. The process of the present invention is simple to operate and environmentally friendly. Different from the chemical reduction and thermal reduction methods used in the conventional reports on the reduction of graphene oxide, this method does not require high temperature or the use of toxic chemical reagents, effectively avoiding potential safety hazards and environmental problems.

[0029] 3. After removing the metal substrate of the modified metal material in the present invention, a large-area pure graphene material is obtained. The size of the prepared graphene film-like material depends on the size of the modified metal material, so it can reach the "meter" level. Description of the Drawings

[0030] Figure 1 The physical picture of the modified metal material prepared in Example 1.

[0031] Figure 2 The physical picture of the modified metal material prepared in Example 2.

[0032] Figure 3 The physical picture of the modified metal material prepared in Example 3.

[0033] Figure 4 The physical picture of the modified metal material prepared in Example 4.

[0034] Figure 5 The physical picture of the modified metal material prepared in Example 5.

[0035] Figure 6 The scanning electron microscope picture of the modified metal material prepared in Example 5.

[0036] Figure 7 The physical picture of the modified metal material prepared in Example 6.

[0037] Figure 8 The scanning electron microscope photograph of the modified metal material prepared in Example 6.

[0038] Figure 9 The Raman spectra of the modified metal materials prepared in Examples 1 to 4.

[0039] Figure 10 The nucleation overpotential test results of the battery prepared in Application Example 1.

[0040] Figure 11 The nucleation overpotential test results of the battery prepared in Application Example 2. Detailed implementation manners

[0041] Based on the prior art, the method of preparing a conductive film using graphene usually adopts the suction filtration method. Although this method can prepare a self-supporting graphene film with good mechanical properties, limited by the size of the suction filtration device and the filter paper, the prepared graphene film often has a size of only 5 cm to 10 cm in diameter. For environments that require large-area conductive films, such as the preparation of liquid crystal displays, the preparation of transparent electrodes for solar cells, and electromagnetic wave shielding, there is an urgent need for a simple and efficient method for preparing large-area graphene conductive films.

[0042] Based on the modified metal material, the present invention also provides a method for preparing a graphene conductive film, which corrodes the modified metal material to remove the metal substrate and obtain the graphene conductive film.

[0043] Preferably, the specific preparation method of the graphene conductive film is as follows: Place the modified metal material in a second acid solution to corrode the metal substrate and obtain the graphene conductive film.

[0044] Preferably, the second acid solution is a dilute hydrochloric acid solution, and the mass concentration of the second acid solution is 1 wt% to 5 wt%.

[0045] Preferably, the time for placing the modified metal material in the second acid solution is 10 min to 120 min.

[0046] In order to enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments and the accompanying drawings.

[0047] In the description of the present invention, unless otherwise specified, the reagents used are commercially available, and the methods used are conventional techniques in the art.

[0048] It should be noted that in specific embodiments of the present invention, the method for preparing graphene oxide is obtained by referring to Document 3: Stankovich, S., Dikin, D.A., Piner, R.D., et al. (2007) Synthesis of Graphene-Based Nanosheets via Chemical Reduction of Exfoliated Graphite Oxide. Carbon, 45, 1558 - 1565.

[0049] Example 1 A preparation method of a modified metal material, comprising the following steps: Place aluminum foil with a size of 2 cm × 2 cm in ethanol and deionized water in sequence, and ultrasonically clean for 30 min; place the water-washed aluminum foil in a dilute hydrochloric acid solution with a mass concentration of 3 wt%, and react at room temperature for 20 min to obtain pretreated aluminum foil.

[0050] Weigh 0.1 g of graphene oxide, and ultrasonically disperse it in 500 mL of deionized water to obtain an aqueous solution of graphene oxide.

[0051] Completely immerse the pretreated aluminum foil in the aqueous solution of graphene oxide with a concentration of 0.2 mg / mL, let it stand at room temperature for 12 h, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the modified metal material.

[0052] Example 2 A preparation method of a modified metal material, comprising the following steps: Place aluminum foil with a size of 2 cm × 2 cm in ethanol and deionized water in sequence, and ultrasonically clean for 30 min; place the water-washed aluminum foil in a dilute hydrochloric acid solution with a mass concentration of 3 wt%, and react at room temperature for 20 min to obtain pretreated aluminum foil.

[0053] Weigh 0.1 g of graphene oxide, and ultrasonically disperse it in 1 L of deionized water to obtain an aqueous solution of graphene oxide.

[0054] Completely immerse the pretreated aluminum foil in the aqueous solution of graphene oxide with a concentration of 0.1 mg / mL, let it stand at room temperature for 12 h, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the modified metal material.

[0055] The difference from Example 1 is: The concentration of the aqueous solution of graphene oxide is 0.1 mg / mL.

[0056] Example 3 A preparation method of a modified metal material, comprising the following steps: Place aluminum foil with a size of 2 cm × 2 cm in ethanol and deionized water in sequence, and ultrasonically clean for 30 min; place the water-washed aluminum foil in a dilute hydrochloric acid solution with a mass concentration of 3 wt%, and react at room temperature for 20 min to obtain pretreated aluminum foil.

[0057] Weigh 0.3 g of graphene oxide, and ultrasonically disperse it in 1 L of deionized water to obtain an aqueous solution of graphene oxide.

[0058] Completely immerse the pretreated aluminum foil in the aqueous solution of graphene oxide with a concentration of 0.3 mg / mL, let it stand at room temperature for 12 h, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the modified metal material.

[0059] The difference from Example 1 is as follows: The concentration of the graphene oxide aqueous solution is 0.3 mg / mL.

[0060] Example 4 A method for preparing a modified metal material, comprising the following steps: Place an aluminum foil with a size of 2 cm × 2 cm successively in ethanol and deionized water, and ultrasonically clean for 30 min; place the water-washed aluminum foil in a dilute hydrochloric acid solution with a mass concentration of 3 wt%, and react at room temperature for 20 min to obtain a pretreated aluminum foil.

[0061] Weigh 0.4 g of graphene oxide, and ultrasonically disperse it in 1 L of deionized water to obtain a graphene oxide aqueous solution.

[0062] Completely immerse the pretreated aluminum foil in the graphene oxide aqueous solution with a concentration of 0.4 mg / mL, let it stand at room temperature for 12 h, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain a modified metal material.

[0063] The difference from Example 1 is as follows: The concentration of the graphene oxide aqueous solution is 0.4 mg / mL.

[0064] Example 5 A method for preparing a modified metal material, comprising the following steps: Place a copper foil with a size of 2 cm × 2 cm successively in ethanol and deionized water, and ultrasonically clean for 30 min; place the water-washed copper foil in a dilute hydrochloric acid solution with a mass concentration of 3 wt%, and react at room temperature for 20 min to obtain a pretreated copper foil.

[0065] Weigh 0.1 g of graphene oxide, and ultrasonically disperse it in 500 mL of deionized water to obtain a graphene oxide aqueous solution.

[0066] Completely immerse the pretreated copper foil in the graphene oxide aqueous solution with a concentration of 0.2 mg / mL, let it stand at room temperature for 12 h, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain a modified metal material.

[0067] The difference from Example 1 is as follows: Use a copper foil to replace the aluminum foil.

[0068] Example 6 A method for preparing a modified metal material, comprising the following steps: After polishing an aluminum foil with a size of 2 cm × 2 cm using sandpaper with a mesh number of 400, place it successively in ethanol and deionized water, and ultrasonically clean for 30 min; place the water-washed aluminum foil in a dilute hydrochloric acid solution with a mass concentration of 3 wt%, and react at room temperature for 20 min to obtain a pretreated aluminum foil.

[0069] Weigh 0.1 g of graphene oxide and ultrasonically disperse it in 500 mL of deionized water to obtain an aqueous solution of graphene oxide.

[0070] Completely immerse the pretreated aluminum foil in the 0.2 mg / mL aqueous solution of graphene oxide. After standing at room temperature for 12 h, dry it in a vacuum drying oven at 60 °C for 8 h to obtain a modified metal material.

[0071] The difference from Example 1 is: Use sandpaper with a mesh number of 400 to polish the aluminum foil to form a pit structure on the surface of the aluminum foil.

[0072] Example 7 A method for preparing a modified metal material, comprising the following steps: After using sandpaper with a mesh number of 400 to polish a 2 cm × 2 cm copper foil, place it successively in ethanol and deionized water and ultrasonically clean it for 30 min; place the copper foil after water washing in a dilute hydrochloric acid solution with a mass concentration of 3 wt% and react at room temperature for 20 min to obtain a pretreated copper foil.

[0073] Weigh 0.1 g of graphene oxide and ultrasonically disperse it in 500 mL of deionized water to obtain an aqueous solution of graphene oxide.

[0074] Completely immerse the pretreated copper foil in the 0.2 mg / mL aqueous solution of graphene oxide. After standing at room temperature for 12 h, dry it in a vacuum drying oven at 60 °C for 8 h to obtain a modified metal material.

[0075] The difference from Example 1 is: Replace the aluminum foil with copper foil and use sandpaper with a mesh number of 400 to polish the copper foil to form a pit structure on the surface of the copper foil.

[0076] Application Example 1 A method for preparing a lithium metal battery, comprising the following steps: Use the modified metal material prepared in Example 1 as the working electrode, a commercial sodium sheet as the counter electrode, sodium hexafluorophosphate as the electrolyte, and a Celgard 2400 polyethylene film as the separator to assemble a button-type 2032 battery in a glove box to obtain a lithium metal battery.

[0077] Application Example 2 A method for preparing a sodium metal battery, comprising the following steps: Use the modified metal material prepared in Example 4 as the working electrode, a commercial sodium sheet as the counter electrode, sodium hexafluorophosphate as the electrolyte, and a Celgard 2400 polyethylene film as the separator to assemble a button-type 2032 battery in a glove box to obtain a lithium metal battery.

[0078] Application Example 3 A method for preparing a graphene conductive film, comprising the following steps: Soak the modified metal material prepared in Example 1 in a 0.1 mol / L dilute hydrochloric acid solution for 0.5 h, then rinse it 3 times with deionized water, and dry it in a vacuum drying oven for 1 h to obtain a graphene conductive film.

[0079] Experimental tests: 1. Surface morphology characterization.

[0080] As Figure 1 shown, soak the aluminum foil in an aqueous solution of graphene oxide at 0.2 mg / mL. After the reaction, a distinct black film-like substance appears on the surface of the modified aluminum foil, indicating that graphene has achieved reduction deposition on the surface of the aluminum foil, and the surface modification of the aluminum foil has been completed.

[0081] As Figure 2 shown, soak the aluminum foil in an aqueous solution of graphene oxide at 0.1 mg / mL. After the reaction, a black film-like substance with a relatively lighter color appears on the surface of the modified aluminum foil, indicating that graphene has achieved reduction deposition on the surface of the aluminum foil, and the surface modification of the aluminum foil has been completed. Compared with the surface of the modified aluminum foil in Example 1, the color change on its surface is relatively lighter, probably because the concentration of graphene oxide is too low, resulting in a smaller amount of reduction deposition.

[0082] As Figure 3 shown, soak the aluminum foil in an aqueous solution of graphene oxide at 0.3 mg / mL. After the reaction, a black film-like substance appears on the surface of the modified aluminum foil, indicating that graphene has achieved reduction deposition on the surface of the aluminum foil, and the surface modification of the aluminum foil has been completed. Compared with the surface of the modified aluminum foil in Example 1, its color has darkened significantly, probably because the concentration of graphene oxide has increased, and within the same time, the amount of reduction deposition has increased.

[0083] As Figure 4 shown, soak the aluminum foil in an aqueous solution of graphene oxide at 0.4 mg / mL. After the reaction, a black film-like substance appears on the surface of the modified aluminum foil, indicating that graphene has achieved reduction deposition on the surface of the aluminum foil, and the surface modification of the aluminum foil has been completed. Compared with the surface of the modified aluminum foil in Example 3, its color has hardly changed. Although the concentration of graphene oxide has increased, within the same time, the amount of reduction deposition has reached saturation, and the final film thickness no longer changes.

[0084] As Figure 5As shown, the copper foil was immersed in an aqueous solution of graphene oxide at 0.4 mg / mL. After the reaction, the surface of the copper foil had a black film, indicating that graphene was reductively deposited on the surface of the copper foil, and the surface modification of the copper foil was completed. Compared with the surface of the modified aluminum foil in Example 4, its surface was smoother, and the film-forming quality was higher than that of the aluminum foil. This may be because the reducibility of aluminum is stronger than that of copper. In the same period of time, its reductive deposition rate is too fast, resulting in uneven distribution of the nuclei formed first. Eventually, with the progress of reductive deposition, the overall film shows a relatively rough surface.

[0085] As Figure 6 shown, using the copper foil as the substrate to reduce graphene oxide, it can be seen that the graphene film is relatively flat.

[0086] As Figure 7 shown, the aluminum foil after surface roughening with sandpaper was immersed in an aqueous solution of graphene oxide at 0.4 mg / mL. After the reaction, the surface of the aluminum foil had a black film, indicating that graphene was reductively deposited on the surface of the aluminum foil, and the modification of the aluminum foil was completed; in addition, the film surface had a granular feeling, which could effectively increase the surface roughness of the aluminum foil and further improve the interfacial bonding strength between the aluminum foil and the graphene film.

[0087] As Figure 8 shown, after the surface of the aluminum foil after surface roughening with sandpaper was reductively deposited with graphene oxide, the pits brought by the sandpaper shaping were still retained on the surface, indicating that the thickness of the reductively deposited graphene film was relatively small; the intact pit array could increase the surface area of the current collector, reduce the local current density, and lower the nucleation barrier of ions, thus being beneficial to the uniform deposition of ions and inhibiting the growth of dendrites.

[0088] 2. Raman test.

[0089] As Figure 9 shown, the carbon films reductively deposited at different concentrations all showed D peaks and G peaks. Among them, the D peak represents the disordered structure or defects of the carbon material, and the G peak is related to the stretching vibration of the carbon-carbon double bond, reflecting the ordered structure of the carbon material. The peak intensity ratio I D / I G ratio is often used to measure the defect degree of the carbon material. The higher the ratio, the more defects. As can be seen from Figure 9, as the concentration increases, the I D / I G ratio gradually decreases, meaning that the defect degree of the carbon material decreases, the graphitization degree increases, and the orderliness improves.

[0090] 3. Electrical property test.

[0091] As Figure 11As shown, the nucleation overpotential of the asymmetric battery prepared in Application Example 1 is 40.6 mV. For the asymmetric battery prepared in Application Example 2, at a current density of 0.5 mA / cm 2 of current density, its nucleation overpotential measured by a charge-discharge tester is 45 mV, which is significantly lower than 62 mV of pure aluminum foil. This indicates that the two modified metal foils have a significant improvement effect on the deposition nucleation of sodium ions, reducing the nucleation barrier of ions, thereby inducing uniform deposition of ions.

[0092] 4. Graphene conductive film testing.

[0093] In the embodiment of the present invention, an ECOPIA HMS-5500 type Hall effect tester is used to conduct conductivity testing on the conductive graphene film prepared in Application Example 3. The results show that the electron mobility of the conductive graphene film is about 1.6×10 4 cm 2 / (V・s), and the carrier mobility is 3×10 3 cm 2 / (V・s). This indicates that the conductive graphene film prepared in the embodiment of the present invention has excellent conductivity.

[0094] In the embodiment of the present invention, a DR-SM type medium-temperature thermal conductivity tester is used to conduct thermal conductivity testing on the conductive graphene film prepared in Application Example 3. The results show that the thermal conductivity of the conductive graphene film is 5000 W / mK. This indicates that the conductive graphene film prepared in the embodiment of the present invention has good thermal conductivity.

[0095] In the embodiment of the present invention, a dynamic elastic modulus tester is used. According to ASTM D5947-14 "Standard Test Method for Measuring Dynamic Young's Modulus, Shear Modulus, and Damping Characteristics Using Vibration Non-Resonance Techniques", at the same time, micro-nano mechanical test standards such as nanoindentation method or uniaxial tensile test are used, and the mechanical properties of the conductive graphene film prepared in Application Example 3 are tested with reference to the framework requirements of GB / T30544.13-2018 "Nanotechnology - Terms and Definitions for Graphene Materials". The results show that the Young's modulus of the conductive graphene film is 0.95 TPa and the tensile strength is 36 GPa, indicating that the conductive graphene film prepared in the embodiment of the present invention has good mechanical strength.

[0096] It should be noted that when the present invention involves a numerical range, it should be understood that any value between the two endpoints of each numerical range and any one of the two endpoints can be selected. Since the adopted step methods are the same as those in the embodiments, in order to prevent repetition, the present invention describes preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept, and these changes and modifications all fall within the scope of the present invention.

[0097] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. If these modifications and variations of the present invention fall within the scope of the equivalent technology of the present invention, the present invention also intends to include these changes and modifications.

Claims

1. A method for preparing a modified metal material, characterized in that, It includes the following steps: Using a metal material as a reduction substrate, immersing the metal material in an aqueous solution of graphene oxide, standing still at room temperature, and driving the reduction reaction of graphene oxide on the surface of the metal material by using the potential difference between the metal and graphene oxide to form a graphene / metal composite structure. After drying, a modified metal material is obtained.

2. The preparation method of the modified metal material according to claim 1, characterized in that, The preparation method of the aqueous solution of graphene oxide is as follows: Disperse graphite oxide in water and exfoliate the graphite oxide by ultrasonic oscillation to obtain an aqueous solution of graphene oxide.

3. The preparation method of the modified metal material according to claim 1, characterized in that, The concentration of the aqueous solution of graphene oxide is 0.1 mg / mL to 1 mg / mL.

4. The preparation method of the modified metal material according to claim 1, characterized in that, The standing time at room temperature is 2 h to 12 h.

5. The preparation method of the modified metal material according to claim 1, characterized in that, The drying conditions are: freeze-drying at -5°C to -55°C for 1 h to 48 h; or drying at 30°C to 100°C for 1 h to 48 h.

6. The preparation method of the modified metal material according to claim 1, characterized in that, The metal material is aluminum, copper, zinc, iron, tin or nickel.

7. A modified metal material, characterized in that, The modified metal material is prepared by the preparation method of the modified metal material according to any one of claims 1 to 6.

8. Application of the modified metal material according to claim 7 as a negative electrode material for a metal ion battery.

9. Use of the modified metal material according to claim 8 as a negative electrode material for a metal ion battery, characterized in that, The metal ion battery is a sodium ion battery, a zinc ion battery, a potassium ion battery or a lithium ion battery.

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