Carbon-coated copper powder and preparation method and application thereof

Abstract

The invention discloses a carbon-coated copper powder and a preparation method and application thereof. The preparation method of the carbon-coated copper powder comprises the following steps: S1. mixing and dissolving urea and glucose, heating reaction, and obtaining a urea precursor; S2. using the urea precursor as a carbon source, and in a reducing atmosphere, chemical vapor deposition is performed on copper powder to form amorphous carbon on the surface of the copper powder, and the carbon-coated copper powder is obtained; the mass ratio of the urea, glucose and copper powder is 10:(1-5):(2-5). The present invention uses a urea precursor prepared from urea and glucose as a carbon source, utilizes chemical vapor deposition, and controls the mass ratio of urea, glucose and copper powder, so that the surface of the copper powder is evenly coated with amorphous carbon, isolates the influence of the environment on the copper powder, and avoids oxidation of the copper powder.

Description

Technical Field

[0001] The invention relates to the technical field of powder engineering, and more specifically to a carbon-coated copper powder and a preparation method and application thereof. Background Art

[0002] From the perspective of regional structure, North America, Europe and Asia-Pacific are the main consumers of primary energy. However, after 2000, Asia-Pacific surpassed North America to become the region with the largest primary energy consumption, and the consumption has continued to rise. From the perspective of energy use structure, the main energy sources of most countries are still oil and natural gas. For example, 97% of the energy sources in the Middle East are oil and natural gas. However, it is worth noting that the primary energy use in major developed countries is declining, while the use of clean energy is increasing. With the increasing importance of clean energy worldwide, a large amount of investment has begun to focus on clean energy, while the investment growth rate of traditional fossil energy has declined or even declined. In the future, the proportion of demand for fossil energy is expected to gradually decline, and the market share will be ceded to clean energy such as hydropower and renewable energy.

[0003] The sun is sending huge amounts of energy to the earth all the time, and it is inexhaustible. The total radiation power emitted by the sun to the earth, converted into electrical power, can be as high as 1.77×10 12 Kilowatts. In the utilization of solar energy, the conversion of solar energy into electrical energy has become the fastest growing and most dynamic research field in recent years. Solar cells use the interaction between sunlight and materials to directly generate electrical energy. They do not consume fuel, water or other substances, and do not release any gases including carbon dioxide. They are a renewable energy source that does not pollute the environment. The use of solar cells is of great significance to improving the ecological environment and alleviating the harmful effects of greenhouse gases.

[0004] The electrodes of solar cells are all printed from electrode paste. Currently, the conductive phase of most electrode pastes is composed of silver powder, which means that most solar cell electrodes currently use silver as the conductive phase. Although silver has high conductivity and good oxidation resistance, it is a precious metal with a high price. In recent years, with the widespread application of silver, its mining volume and reserves have gradually failed to meet demand, resulting in its market price rising steadily. This may lead to the scale of human solar energy utilization in the future being limited by insufficient silver production. At present, the market is in urgent need of a material that can replace silver as the conductive phase. The market price of copper is one percent of that of silver, and its reserves are 1,000 times that of silver. Its conductivity (1.7×10 -8 Ω·m) is only slightly lower than silver (1.6×10 -8 Ω·m), therefore, copper is a good substitute for silver. However, the chemical properties of copper are extremely unstable. Especially when it is exposed to water, oxygen, sulfide and other environments, it is very easy to be oxidized, which will cause the electrical conductivity of copper to drop sharply, which is not conducive to its use.

[0005] Therefore, developing a carbon-coated copper powder that can help copper isolate environmental influences and prevent copper from being oxidized has important economic value. Summary of the invention

[0006] The purpose of the present invention is to solve the deficiencies of the prior art and to provide a carbon-coated copper powder and a preparation method and application thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a method for preparing carbon-coated copper powder, the preparation method comprising the following steps:

[0009] S1. Preparation of urea precursor

[0010] Mix and dissolve urea and glucose, and heat them for reaction to obtain a urea precursor;

[0011] S2. Preparation of Carbon-coated Copper Powder

[0012] Using urea precursor as carbon source, chemical vapor deposition is performed on copper powder in a reducing atmosphere to form amorphous carbon on the surface of the copper powder, thus obtaining carbon-coated copper powder;

[0013] The mass ratio of urea, glucose and copper powder is 10:(1-5):(2-5).

[0014] The present invention uses a urea precursor prepared from urea and glucose as a carbon source, utilizes chemical vapor deposition, and controls the mass ratio of urea, glucose and copper powder to uniformly coat the surface of the copper powder with amorphous carbon, thereby isolating the copper powder from environmental influences and preventing the copper powder from being oxidized.

[0015] The reason why the present invention chooses to use urea precursor prepared by urea and glucose as the carbon source is that the amorphous carbon lattice formed by urea and glucose on the surface of the copper powder is disordered, and the amorphous carbon layers are not easy to slip, so that the internal structure of the amorphous carbon becomes dense, which can well isolate the influence of the environment on the copper powder; in addition, urea and glucose are inexpensive, easy to obtain, and easy to promote and use.

[0016] As a preferred embodiment of the method for preparing carbon-coated copper powder of the present invention, the mass ratio of urea, glucose and copper powder is 10:1:(2-5), and more preferably, the mass ratio of urea, glucose and copper powder is 10:1:(4-5).

[0017] As a preferred embodiment of the method for preparing carbon-coated copper powder of the present invention, the solvent for dissolving urea and glucose in step S1 is at least one of water, anhydrous ethanol, methanol, and isopropanol. When water and anhydrous ethanol are selected as solvents for dissolving urea and glucose, the volume ratio of water to anhydrous ethanol is 1:(2-5), and more preferably, the volume ratio of water to anhydrous ethanol is 1:3.

[0018] As a preferred embodiment of the method for preparing carbon-coated copper powder of the present invention, the temperature of the heating reaction in step S1 is 50-80°C and the time is 1-2h; more preferably, the temperature of the heating reaction in step S1 is 70°C and the time is 2h.

[0019] As a preferred embodiment of the method for preparing the carbon-coated copper powder of the present invention, after the heating reaction in step S1, the reaction solution needs to be freeze-dried.

[0020] As a preferred embodiment of the method for preparing carbon-coated copper powder of the present invention, the reducing atmosphere in step S2 is at least one of hydrogen-containing gas, carbon monoxide-containing gas, methane-containing gas, and ethane-containing gas. More preferably, the hydrogen-containing gas is at least one of pure hydrogen, argon-hydrogen mixed gas, hydrogen-helium mixed gas, hydrogen-nitrogen mixed gas, and methane-hydrogen mixed gas; the methane-containing gas is at least one of methane and methane-hydrogen mixed gas; and the ethane-containing gas is ethane.

[0021] As a preferred embodiment of the method for preparing the carbon-coated copper powder of the present invention, the chemical vapor deposition needs to be firstly reacted at a constant temperature of 200-400°C, and then at a constant temperature of 500-650°C, specifically, firstly at a constant temperature of 200-400°C for 2-6h, and then at a constant temperature of 500-650°C for 10-15h. More preferably, the chemical vapor deposition needs to be firstly reacted at a constant temperature of 300°C for 4h, and then at a constant temperature of 550°C for 10h.

[0022] In the present invention, when chemical vapor deposition is performed on copper powder using a urea precursor as a carbon source, the chemical vapor deposition is divided into two-step reactions in order to perform carbon coating twice on the surface of the copper powder to improve the effect of carbon coating; and the carbon coating is first performed at a low temperature (200-400°C) and then at a high temperature (500-650°C), which can make it more difficult for the amorphous carbon layers to slip, and make the internal structure of the amorphous carbon become denser, thereby better isolating the copper powder from the influence of the environment.

[0023] In addition, the reason why the temperature of chemical vapor deposition is controlled to be less than 700°C in the present invention is that excessively high temperature (≥700°C) will cause the prepared carbon-coated copper powder to agglomerate and agglomerate, and the agglomerated and agglomerated carbon-coated copper powder is difficult to form into a slurry when preparing electrode slurry, which is not conducive to the preparation of electrode slurry.

[0024] As a preferred embodiment of the method for preparing carbon-coated copper powder of the present invention, the heating rate of the chemical vapor deposition is 5-10° C. / min. More preferably, the heating rate of the chemical vapor deposition is 5° C. / min.

[0025] As a preferred embodiment of the method for preparing the carbon-coated copper powder of the present invention, the particle size of the copper powder is 1-5 μm, and the shape of the copper powder is granular. The copper powder needs to be degreased and pickled before use to remove the oil layer and possible oxide layer on the surface of the copper powder, and sodium hydroxide or detergent is used for degreasing, and dilute sulfuric acid or dilute hydrochloric acid is used for pickling.

[0026] In a second aspect, the present invention provides a carbon-coated copper powder prepared by the above-mentioned preparation method.

[0027] In a third aspect, the present invention provides the use of carbon-coated copper powder in preparing electrode slurry.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention uses a urea precursor prepared from urea and glucose as a carbon source, utilizes chemical vapor deposition, and controls the mass ratio of urea, glucose and copper powder to uniformly coat the surface of the copper powder with amorphous carbon, thereby isolating the copper powder from environmental influences and preventing the copper powder from being oxidized. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the TEM image of the carbon-coated copper powder of Example 1.

[0031] Figure 2 This is the SEM image of the carbon-coated copper powder of Example 1.

[0032] Figure 3 This is the SEM image of the carbon-coated copper powder of Comparative Example 1.

[0033] Figure 4 This is the SEM image of the carbon-coated copper powder of Example 2.

[0034] Figure 5 This is the finished product picture of the carbon-coated copper powder of Example 1.

[0035] Figure 6 This is the Raman spectrum of the carbon-coated copper powder in Example 1.

[0036] Figure 7 This is the SEM image of the carbon-coated copper powder of Example 6.

[0037] Figure 8 This is the finished product picture of the carbon-coated copper powder of Example 6.

[0038] Fig. 9 This is the Raman spectrum of the carbon-coated copper powder of Example 6.

[0039] Fig.10 This is the SEM image of the carbon-coated copper powder of comparative example 2.

[0040] Fig.11 This is the SEM image of the carbon-coated copper powder of comparative example 3. DETAILED DESCRIPTION

[0041] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0042] Example 1

[0043] This embodiment provides a carbon-coated copper powder, and the preparation method thereof comprises the following steps:

[0044] S1. Preparation of urea precursor

[0045] 10 g urea and 1 g glucose were added to water and anhydrous ethanol in a volume ratio of 1:3, and ultrasonic stirring was performed for 15 min to mix and dissolve the urea and glucose. The mixture was transferred to an oil bath and heated at 70°C for 2 h. The reaction solution was taken out, allowed to stand for 0.5 h, and freeze-dried at -50°C for 10 h to obtain a urea precursor.

[0046] S2. Preparation of Carbon-coated Copper Powder

[0047] (1) First, the copper powder is placed in a 1 mol / L sodium hydroxide solution for ultrasonic cleaning for 0.5 h to remove oil, then washed with water and dried, and then the copper powder is placed in a 5% by mass dilute hydrochloric acid solution for ultrasonic cleaning for 0.5 h to acid wash, then washed with water, filtered, and dried at 50° C. in vacuum for 12 h to complete the degreasing and acid washing treatment of the copper powder;

[0048] (2) taking 4 g of the copper powder after the degreasing and pickling treatment, and placing it together with the urea precursor prepared in step S1 into the reaction chamber of a tubular furnace, and introducing hydrogen and argon into the reaction chamber to form an argon-hydrogen mixed gas, and the hydrogen flow rate is 120 sccm, and the argon flow rate is 120 sccm, and chemical vapor deposition is performed on the copper powder, specifically, the temperature is increased at a heating rate of 5°C / min, first at 300°C for 4 hours, and then at 550°C for 10 hours, so that amorphous carbon is formed on the surface of the copper powder, and carbon-coated copper powder is obtained;

[0049] The mass ratio of the urea, glucose and copper powder is 10:1:4; the particle size of the copper powder is 1 μm, and the shape of the copper powder is granular.

[0050] Examples 2-3 and Comparative Example 1

[0051] Examples 2-3 and Comparative Example 1 provide different carbon-coated copper powders and preparation methods thereof, which differ from Example 1 in that the mass ratios of urea, glucose and copper powder are different, and the rest are consistent with Example 1, as shown in the following table:

[0052] Table 1 Mass ratio of urea, glucose and copper powder in Examples 1-3 and Comparative Example 1

[0053] Urea / g Glucose / g Copper powder / g Mass ratio of urea, glucose and copper powder Example 1 10 1 4 10:1:4 Example 2 10 1 2 10:1:2 Example 3 10 1 5 10:1:5 Comparative Example 1 10 1 6 10:1:6

[0054] Embodiment 4-6

[0055] Embodiments 4-6 provide different carbon-coated copper powders and preparation methods thereof, which differ from Embodiment 1 in that the temperature of the second step isothermal reaction in step S2 is different, and the rest are consistent with Embodiment 1, as shown in the following table:

[0056] Table 2 The second step isothermal reaction in step S2 of Examples 1 and 4-6

[0057]

[0058]

[0059] Comparative Example 2

[0060] This comparative example provides a carbon-coated copper powder, which uses methane as a carbon source, and a preparation method thereof comprises the following steps:

[0061] (1) First, the copper powder is placed in a 1 mol / L sodium hydroxide solution for ultrasonic cleaning for 0.5 h to remove oil, then washed with water and dried, and then the copper powder is placed in a 5% by mass dilute hydrochloric acid solution for ultrasonic cleaning for 0.5 h to acid wash, then washed with water, filtered, and dried at 50° C. in vacuum for 12 h to complete the degreasing and acid washing treatment of the copper powder;

[0062] (2) 4 g of copper powder after degreasing and pickling treatment was taken, placed in a reaction chamber of a tubular furnace, evacuated, introduced hydrogen at a flow rate of 120 sccm, heated to 500° C., started plasma preheating for 10 min, and then introduced methane and hydrogen at a flow rate ratio of 40:1 at the same time, at a flow rate of 120 sccm of hydrogen, and reacted for 30 min to obtain carbon-coated copper powder;

[0063] The copper powder has a particle size of 1 μm and is in a granular shape.

[0064] Comparative Example 3

[0065] This comparative example provides a carbon-coated copper powder, which uses graphene oxide as a carbon source, and a preparation method thereof comprises the following steps:

[0066] 0.5 mL of 10 mg / mL graphene oxide aqueous solution was diluted in 20 mL of methanol, and then, under stirring, 2.5 mL of 20 mg / mL toluene suspension containing copper powder was added, and then, ultrasonic treatment was performed for 5 minutes to form a carbon coating layer on the surface of the copper powder, and the product was separated by centrifugation at 7000 rpm for 10 minutes. Finally, the product was washed with isopropanol through a centrifugation-dispersion-centrifugation cycle to remove impurities, and carbon-coated copper powder was obtained;

[0067] The copper powder has a particle size of 1 μm and is in a granular shape.

[0068] Sample characterization

[0069] The carbon-coated copper powder of each embodiment and comparative example was characterized.

[0070] Figure 1 This is the TEM image of the carbon-coated copper powder of Example 1. Figure 2 This is the SEM image of the carbon-coated copper powder of Example 1. Figure 3 This is the SEM image of the carbon-coated copper powder of Comparative Example 1. Figure 4 1 is a SEM image of the carbon-coated copper powder of Example 2. The TEM image and SEM image of the carbon-coated copper powder of Example 3 are similar to those of Example 1.

[0071] from Figure 1-4 It can be seen that the present invention controls the mass ratio of urea, glucose and copper powder to 10:(1-5):(2-5), so that the surface of the copper powder is evenly coated with amorphous carbon, thereby isolating the influence of the environment on the copper powder and preventing the copper powder from being oxidized; while in Comparative Example 1, due to the inappropriate mass ratio of urea, glucose and copper powder, the copper powder is not evenly coated with amorphous carbon, and a large amount of copper powder is not coated with amorphous carbon, and at the same time, the amorphous carbon is aggregated away from the copper powder, thereby failing to isolate the influence of the environment on the copper powder and failing to prevent the copper powder from being oxidized.

[0072] Figure 5 This is the finished product picture of the carbon-coated copper powder of Example 1. Figure 6 This is the Raman spectrum of the carbon-coated copper powder in Example 1. Figure 7 This is the SEM image of the carbon-coated copper powder of Example 6. Figure 8 This is the finished product picture of the carbon-coated copper powder of Example 6. Fig. 9 The Raman spectrum of the carbon-coated copper powder of Example 6. The SEM images, finished product images, and Raman spectrum of the carbon-coated copper powder of Examples 4-5 are similar to those of Example 1.

[0073] from Figure 5-9 It can be seen that the reason why the temperature of chemical vapor deposition is controlled to be less than 700°C in the present invention is that if the temperature is too high (≥700°C), such as 700°C in Example 6, the prepared carbon-coated copper powder will be agglomerated and agglomerated. The agglomerated and agglomerated carbon-coated copper powder is not suitable for preparing electrode slurry and will affect the performance of the electrode prepared using it.

[0074] Fig.10 This is the SEM image of the carbon-coated copper powder of comparative example 2. Fig.11 This is the SEM image of the carbon-coated copper powder of comparative example 3.

[0075] from Figure 2 , 10 -11 It can be seen that the carbon-coated copper powder prepared by the present invention using urea precursor prepared from urea and glucose as a carbon source, utilizing chemical vapor deposition, and controlling the mass ratio of urea, glucose and copper powder can make the surface of the copper powder be evenly coated with amorphous carbon; while in comparative example 2, when methane is used as a carbon source, the carbon cannot be evenly covered on the surface of the copper powder because the copper powder still maintains its original granular shape; when comparative example 3 uses graphene oxide as a carbon source, the carbon formed cannot be completely coated on the surface of the copper powder, and the effect of isolating the environment is poor. At the same time, it is easy to wrap multiple copper powders together. In actual use, the multiple copper powders that are wrapped are easy to separate, causing the carbon to break and lose the function of isolating the environment.

[0076] Performance Testing

[0077] Taking the untreated copper powder as the control group, the carbon-coated copper powder of Example 1 and Comparative Example 1 was subjected to an aging performance test, and the specific test method was as follows:

[0078] Under the conditions of temperature 85℃ and humidity 85%RH, the carbon-coated copper powder was aged in an aging box for 5 hours, and the resistance value before and after aging was tested. The test results are as follows:

[0079] Table 3 Performance test results of carbon-coated copper powder of Example 1 and Comparative Example 1

[0080]

[0081]

[0082] As can be seen from Table 3, the resistance of the carbon-coated copper powder of Example 1 before and after aging is the closest, indicating that the present invention controls the mass ratio of urea, glucose and copper powder to 10:(1-5):(2-5), so that the surface of the copper powder is evenly coated with amorphous carbon, the influence of the environment on the copper powder is isolated, and the copper powder is prevented from being oxidized, while still maintaining good conductivity.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing carbon-coated copper powder, characterized in that: The preparation method comprises the following steps: S1. Preparation of urea precursor Mix and dissolve urea and glucose, and heat them for reaction to obtain a urea precursor; S2. Preparation of Carbon-coated Copper Powder Using urea precursor as carbon source, chemical vapor deposition is performed on copper powder in a reducing atmosphere to form amorphous carbon on the surface of the copper powder, thus obtaining carbon-coated copper powder; The mass ratio of urea, glucose and copper powder is 10:1:(2-5); The chemical vapor deposition needs to be reacted at a constant temperature of 200-400°C first, and then at a constant temperature of 500-650°C.

2. The method for preparing carbon-coated copper powder according to claim 1, characterized in that: The chemical vapor deposition needs to first be subjected to a constant temperature reaction at 200-400° C. for 2-6 hours, and then to be subjected to a constant temperature reaction at 500-650° C. for 10-15 hours.

3. The method for preparing carbon-coated copper powder according to claim 1, characterized in that: The temperature of the heating reaction in step S1 is 50-80°C.

4. The method for preparing carbon-coated copper powder according to claim 1, characterized in that: The solvent for dissolving urea and glucose in step S1 is at least one of water, anhydrous ethanol, methanol and isopropanol.

5. The method for preparing carbon-coated copper powder according to claim 1, characterized in that: After the heating reaction in step S1, the reaction solution needs to be freeze-dried.

6. The method for preparing carbon-coated copper powder according to claim 1, characterized in that: The reducing atmosphere in step S2 is at least one of hydrogen-containing gas, carbon monoxide-containing gas, methane-containing gas, and ethane-containing gas.

7. A carbon-coated copper powder prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the carbon-coated copper powder according to claim 7 in preparing electrode slurry.

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