A method for increasing the specific surface area of graphene by electrochemical method
By using an easily decomposable or volatile electrolyte solution for re-intercalation after electrolysis, the interlayer bursting force of graphite is enhanced, solving the problem of insufficient specific surface area of graphene produced by electrochemical methods, and realizing efficient and low-cost graphene production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG HENGHUA NEW MATERIAL CO LTD
- Filing Date
- 2025-09-12
- Publication Date
- 2026-05-15
AI Technical Summary
Existing electrochemical methods for preparing graphene have limited specific surface areas to reach 600 m²/g or higher, and these methods are costly and inefficient, failing to meet the demands of high-end applications.
After the electrolysis process, one or more easily decomposed or volatile electrolyte solutions are used for reintercalation. Through uniform mixing and high-temperature expansion, the bursting force between graphite layers is enhanced, and the specific surface area of graphene is increased.
Significantly increase the specific surface area of graphene, reduce production costs, achieve clean and stable large-scale production, and meet the needs of high-end applications.
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Figure CN120943244B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of graphene preparation technology, and in particular to a method for increasing the specific surface area of electrochemically produced graphene. Background Technology
[0002] Graphene is a novel two-dimensional carbon nanomaterial whose unique microstructure endows it with many excellent properties in optics, electricity, mechanics, and thermal fields. It has broad application prospects in energy storage devices, electronic devices, and composite materials. The industrial production of graphene has been a hot topic in international materials science research in recent years.
[0003] Currently, common methods for preparing graphene include mechanical exfoliation, redox methods, epitaxial growth, chemical vapor deposition (CVD), flame methods, and electrochemical methods. Among these methods, only the redox method and the electrochemical method can be used for large-scale production of graphene powder.
[0004] The basic principle of electrochemical graphene preparation is as follows: In an electrolyte, using a graphite electrode as the anode or cathode (or a composite electrode made of graphite flakes), under the influence of an electric field, anions or cations in the electrolyte are driven to intercalate into the graphite layers within the graphite electrode or graphite flake composite electrode. This causes the electrode volume to expand, reducing the interlayer van der Waals forces and resulting in graphite intercalations containing a large number of anions or cations—or high-quality expandable graphite. These intercalations are then chemically or thermally treated to ultimately exfoliate few-layer or single-layer graphene powder.
[0005] Compared to redox methods, it eliminates the need for strong oxidants, strong reducing agents, and toxic reagents, resulting in lower costs and greater environmental friendliness. Furthermore, the electrochemical method allows for more ion insertion during the exfoliation process, minimizing damage to the graphene structure. In addition, the electrochemical preparation method is simple and easy to implement; precise control of current and voltage facilitates the controllable preparation and performance regulation of graphene. More importantly, my country possesses abundant graphite resources, providing a uniquely advantageous and high-quality raw material for the electrochemical preparation of graphene.
[0006] Therefore, the electrochemical method for preparing graphene is highly regarded in the industry due to its unique advantages. Many reputable universities and research institutions, both domestically and internationally, have established R&D teams for the large-scale preparation of graphene using the electrochemical method. However, due to the specific working conditions required for the electrochemical method, most studies are limited to the initial R&D stage of low-end graphene powders.
[0007] Specific surface area is a crucial indicator of graphene powder quality, representing the degree of graphite exfoliation after appropriate processing, measured in m² / g. A larger specific surface area indicates a higher graphene monolayer ratio, leading to more advanced and widespread applications. In current electrochemical methods for graphene preparation, graphite or graphite flakes undergo electrolytic intercalation, followed by washing with pure water to remove surface electrolyte, drying, and expansion at a certain temperature. The specific surface area is typically between 300-500 m² / g, rarely exceeding 600 m² / g. The larger the specific surface area, the more difficult it is to improve. Summary of the Invention
[0008] To address the problems existing in the prior art, this invention provides a method for increasing the specific surface area of electrochemically produced graphene. This invention employs an electrochemical graphene preparation process that is safe to operate, low in cost, simple, easy to operate, and convenient for industrial application. It further enhances the exfoliation degree of electrochemically produced graphene, enabling the specific surface area of the powder product to reach over 600 m² / g. This forms a clean, civilized, stable, and reliable large-scale industrial production process, producing higher-quality graphene products to meet the increasingly broad market demand.
[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:
[0010] During electrolysis, graphite electrodes or composite flake graphite electrodes are influenced by an electric field. Ions in the electrolyte gain a driving force, thus embedding themselves between graphite layers and opening them. As electrolysis continues, the distance between graphite layers further increases, causing the graphite layers to expand in volume, leading to mutual compression and increased layer density. Due to limitations in the working environment, the distribution of electrolyte around the graphite flakes cannot achieve ideal uniformity. This results in electrolyte deficiency around the intercalated graphite flakes, preventing electrolyte ions from being inserted into some of the opened graphite interlayers in time. This leads to insufficient intercalation of electrolyte ions in the graphite flakes, reducing the degree of electrolysis and ultimately affecting the content and quality of single-layer graphene in the graphene powder.
[0011] To ensure that the electrolyte ions or molecules involved in graphite intercalation generate the largest possible separating or bursting force between graphite layers during graphene powder preparation, thus overcoming the van der Waals forces between layers, one or more substances whose molecules decompose or volatilize upon heating are selected and prepared into a re-intercalation solution of a certain concentration. This solution is then used to uniformly mix the electrolyzed graphite intercalation material and perform a slurry preparation process. After a period of time, the electrolyte intercalation relay can be achieved, further enhancing the intercalation effect of electrolyte ions on graphite flakes based on electrolytic intercalation.
[0012] These specific electrolytes can completely separate from graphene powder upon heating without affecting the powder purity. Generally, electrolytes that are easily decomposed or volatile upon heating and have different ionic radii are selected. For example, HNO3 and HClO4 are easily decomposed or vaporized upon heating, especially at high temperatures, resulting in anionic clusters with varying ionic radii after reintercalation: ClO4... - The ionic radius is 150 pm; NO3 - With an ionic radius of 179-200 pm, after electrolysis, the material is uniformly mixed and fully contacted in the reintercalation solution. Electrolyte ions or water molecules of varying sizes fill the gaps between graphite layers, increasing the number of electrolyte ions in the graphite layers. During the drying process of the intercalated material, the moisture between the graphite layers evaporates, but the electrolyte ions or molecules remain within the graphite layers. When the graphite intercalation expands, the increased amount of gas generated by decomposition and volatilization between the graphite layers results in a greater explosive force.
[0013] For example, if the processed electrolytic material is rapidly placed in a working environment above 200°C, the intercalated electrolyte, except for the electrolytically intercalated electrolyte, will undergo a violent decomposition reaction:
[0014] The decomposition reaction equation for nitric acid is as follows:
[0015]
[0016] The decomposition reaction equation of perchloric acid is as follows:
[0017]
[0018] The instantaneous generation of a large amount of gas between graphite layers creates an explosive force, which, together with the decomposition reaction of the electrolyte in the initial electrolytic intercalation, forms a combined force. This increases the ability to overcome the van der Waals forces between layers, thereby enhancing the expansion effect and ultimately yielding graphene powder with a higher specific surface area.
[0019] This invention adds a re-intercalation step to the graphite electrolytic material before washing away the electrolyte: different re-intercalation solutions are used to uniformly mix and fully contact the graphite electrolytic material. After a period of time, electrolyte ions or water molecules of varying sizes in the electrolyte can enter and fill the gaps between the graphite layers, increasing the number of electrolyte ions between the graphite layers.
[0020] After the intercalated material undergoes a drying process, the moisture between the graphite layers evaporates, while the electrolyte ions or molecules remain within the graphite layers. This increases the number of easily decomposable and volatile electrolyte ions or molecules between the graphite layers, creating conditions for greater explosive force between the subsequent graphite intercalation layers. Specifically, a method for increasing the specific surface area of electrochemically produced graphene includes:
[0021] Step 1: Mix graphite flakes (150 mesh) at a ratio of 2g / cm 3 The material is loaded into the material chamber and squeezed to form an electrolysis unit. The ion membrane can effectively prevent the graphite flakes from being exposed during the extrusion process.
[0022] Step 2: Intercalation of graphite is performed using an electrochemical method. The electrolysis voltage is 5V, the current is 44A, and the energizing time is 4h. After electrolysis, the graphite electrolytic material is collected. The electrolyte during the electrolysis process is a mixture of perchloric acid solution and hydrochloric acid solution with a mass ratio of 5:1. The concentration of the perchloric acid solution is 30~40wt%, and the concentration of the hydrochloric acid solution is 15~20wt%.
[0023] Step 3: Weigh the reintercalation solution, then add the graphite electrolytic material from Step 2 to it, stir evenly, and soak for 1 hour; the mass ratio of the reintercalation solution to the graphite electrolytic material is 10:1; the reintercalation solution is HNO3 solution, HClO4 solution, or a mixture of HNO3 solution and HClO4 solution with a mass ratio of 1:1.
[0024] The concentration of the HNO3 solution is 50 wt%; the concentration of the HClO4 solution is 50 wt%.
[0025] Step 4: Centrifuge the above system at 2000 rpm for 5 min; remove the supernatant, add deionized water, centrifuge again until the supernatant is neutral, and then dry at 60℃ for 24 h to obtain the graphite intercalation material.
[0026] Step 5: Place the graphite intercalation material in a muffle furnace at 360℃ under a nitrogen atmosphere for high-temperature expansion treatment to obtain high specific surface area graphene.
[0027] Compared with the prior art, the present invention has the following beneficial effects:
[0028] (1) The specific surface area of graphene in this invention is significantly improved. After the electrolytic material and different reintercalation solutions are uniformly mixed and fully contacted with the graphite electrolytic material for a period of time, the specific surface area of the graphene powder prepared from the graphite intercalation material is significantly increased.
[0029] (2) In the prior art, if the intercalation effect of graphene prepared by electrochemical method is to be improved, it is often achieved by adjusting the voltage or electrolysis time, which will increase power consumption and production cost. The graphite electrolysis material is uniformly mixed with the reintercalation solution and slurryed. The process is simple and achieves the same effect with less power consumption and lower cost.
[0030] (3) The amount of electrolytic material and reintercalation solution that completes reintercalation is less than 5% of the graphite flakes, and most of it can be recycled and reused, so it has little impact on cost. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the anode chamber structure;
[0032] Figure 2 This is a schematic diagram of the cathode chamber structure;
[0033] Figure 3 This is a cross-sectional view of the electrolytic cell;
[0034] Figure 4 This is a front view of the electrolytic cell;
[0035] The components include: cathode plate 1, ion exchange membrane 2, mesh anode plate 3, cathode chamber 4, anode chamber 5, filter cloth 6, material chamber 7, mesh support plate 8, support frame 9, anolyte inlet 10, cathodelyte inlet 11, anolyte gas outlet 12, cathodelyte gas outlet 13, feed port 14, and liquid distribution plate 15. Detailed Implementation
[0036] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific drawings and embodiments.
[0037] Unless otherwise specified, all materials and devices used in this invention are commercially available. The diameter of the graphite flakes is 150 mesh. In the following embodiments and comparative examples of this invention, where the electrochemical intercalation process is involved, the electrolyte is a mixture of perchloric acid solution and hydrochloric acid solution with a mass ratio of 5:1. The concentration of the perchloric acid solution is 30 wt%, and the concentration of the hydrochloric acid solution is 15 wt%.
[0038] The electrolysis unit of this invention is an electrolytic cell, which includes a cathode plate 1, an ion exchange membrane 2, and a mesh anode plate 3 arranged sequentially. The ion exchange membrane 2 divides the electrolytic cell into a cathode chamber 4 and an anode chamber 5. The cathode plate 1 is located in the cathode chamber 4, and the mesh anode plate 3 is located in the anode chamber 5. A feed chamber 7 is provided between the mesh anode plate 3 and the ion exchange membrane 2. Filter cloth 6 is provided in the feed chamber 7 near both the mesh anode plate 3 and the ion exchange membrane 2. Graphite flakes are added to the feed chamber 7, and the filter cloth 6 prevents the graphite flakes or intercalated materials from detaching from the feed chamber 7. The top of the mesh anode plate 3 is connected to the positive terminal of the power supply. The cathode plate 1 is directly connected to the negative terminal of the power supply.
[0039] A mesh support plate 8 and a support frame 9 are provided between the ion exchange membrane 2 and the cathode plate 1. The support frame 9 is fixed on one side of the cathode plate 1, and the mesh support plate 8 is fixed on the support frame 9. The mesh support plate 8 is used to provide mechanical support for the ion exchange membrane 2.
[0040] After the graphite flakes are loaded into the material chamber 7, the graphite flakes are squeezed together by moving the cathode plate 1.
[0041] The ion exchange membrane 2 allows charged ions in the electrolyte to pass through, while air bubbles in the solution cannot pass through and can only be discharged from the outlet with the liquid flow. The cathode plate 1 is a graphite electrode plate.
[0042] Anode chamber 5 and cathode chamber 4 are respectively provided with anolyte inlet 10 and cathode inlet 11 at their bottoms. Anode inlet 10 is provided with a liquid distribution plate 15 in the electrolytic cell, which is fixed to the mesh anode plate. Anode liquid-gas outlet 12 and cathode liquid-gas outlet 13 are respectively provided at their tops. A feed port 14 is provided at the top of material chamber 7 for adding graphite flakes.
[0043] During normal operation, graphite flakes are first added and then squeezed to prepare an electrolyte. The electrolyte is then pumped into the electrolytic cell from the anolyte inlet and the cathode inlet using an electrolyte pump until a small amount of electrolyte continuously flows out from the two gas-liquid outlets at the cathode and anode. The electrolytic material is then removed from the tank after electrolysis is completed.
[0044] This invention provides a method for increasing the specific surface area of electrochemically produced graphene, and specific embodiments are as follows.
[0045] Example 1
[0046] A method for increasing the specific surface area of electrochemically produced graphene includes:
[0047] Step 1: Weigh 100g of graphite flakes according to 2g / cm³ 3 The density of the material is fed into the material chamber through the feeding port and squeezed to form an electrolysis unit. The electrolyte is then added to the electrolysis cell from the anolyte inlet and the cathode inlet by the electrolyte pump.
[0048] Step 2: Connect the anode and cathode of the electrolysis unit to the positive and negative terminals of a DC power supply, respectively, and energize them. The voltage is 5V, the current is 44A, and the energizing time is 4h. After electrolysis is completed, collect the electrolyzed materials.
[0049] Step 3: Weigh 200g of 50% HNO3 solution into a 500ml glass beaker as the reintercalation solution. Weigh 20g of the electrolytic material into a 500ml glass beaker. Pour the HNO3 solution into the electrolytic material and stir thoroughly at room temperature until the mixture is homogeneous to form a slurry. Soak for 1 hour to ensure that the reintercalation solution and the electrolytic material are in full contact.
[0050] Step 4: Then, centrifuge at 2000 rpm for 5 minutes, remove the supernatant, add deionized water and centrifuge again until the supernatant is neutral, and then dry in a 60℃ drying oven for 24 hours to obtain the graphite intercalation material.
[0051] Step 5: Weigh 0.3000g (±0.0050g) of the dried graphite intercalation material, place it in a muffle furnace, heat at 360℃ for 1min, and cool to room temperature to obtain graphene with high specific surface area.
[0052] Example 2
[0053] A method for increasing the specific surface area of electrochemically produced graphene includes:
[0054] Steps 1-2 are the same as in Example 1;
[0055] Step 3: Weigh 100g each of 50% HNO3 solution and HClO4 solution into a 500ml glass beaker, and stir thoroughly until homogeneous to obtain the reintercalation solution. Weigh 20g of the electrolytic material into a 500ml glass beaker, pour the reintercalation solution into the electrolytic material, and stir thoroughly at room temperature until homogeneous to form a slurry. Soak for 1 hour to ensure full contact between the reintercalation solution and the electrolytic material.
[0056] Steps 4-5 are the same as in Example 1.
[0057] Example 3
[0058] In this embodiment, the HNO3 solution was replaced with an HClO4 solution of equal concentration and mass, and the other conditions were the same as in Example 1.
[0059] To further illustrate the beneficial effects of the present invention, the following comparative examples were constructed.
[0060] Comparative Example 1
[0061] This comparative example includes steps 1-4, wherein steps 1-2 are the same as in Example 1; step 3 is: the collected electrolytic material is washed with pure water to remove the surface electrolyte, and then dried in a drying oven at 60°C for 24 hours to obtain the graphite intercalation material; step 4 is the same as step 5 in Example 1.
[0062] Comparative Example 2
[0063] In this comparative example, the HNO3 solution was replaced with an H2SO4 solution of equal concentration and mass, and the other conditions were the same as in Example 1.
[0064] Comparative Example 3
[0065] In this comparative example, the HNO3 solution was replaced with an H3PO4 solution of equal concentration and mass, and the other conditions were the same as in Example 1.
[0066] Comparative Example 4
[0067] A method for preparing graphene, comprising:
[0068] Step 1: Weigh 200g of 50% HNO3 solution into a 500ml glass beaker, weigh 20g of graphite flakes into a 500ml glass beaker, pour the HNO3 solution into the graphite flakes, stir thoroughly at room temperature until evenly mixed to form a slurry, and soak for 1 hour.
[0069] Step 2: Then, centrifuge at 2000 rpm for 5 minutes, remove the supernatant, add deionized water and centrifuge again until the supernatant is neutral, and then dry in a 60℃ drying oven for 24 hours to obtain the first intercalated material;
[0070] Step 3: Weigh 100g of the above-mentioned initial intercalation material, according to 2g / cm 3 The material is packed into the cavity between the cathode plate and the anode plate and squeezed tightly to form an electrolysis unit. This electrolysis unit is then placed into an electrolysis cell containing electrolyte.
[0071] Step 4: Connect the anode and cathode of the electrolysis unit to the positive and negative terminals of a DC power supply, respectively, and energize them. The voltage is 5V, the current is 44A, and the energizing time is 4h. After electrolysis is completed, collect the electrolyzed materials.
[0072] Step 5: Then centrifuge at 2000 rpm for 5 min, remove the supernatant, add deionized water and centrifuge again until the supernatant is neutral, and then dry in a 60℃ drying oven for 24 h to obtain graphite intercalation material;
[0073] Step 6: Weigh 0.3000g (±0.0050g) of the dried graphite intercalation material, place it in a muffle furnace, heat at 360℃ for 1min, and cool to room temperature to obtain graphene.
[0074] The specific surface area of the graphene prepared in the above examples and comparative examples was measured, and the results are shown in Table 1.
[0075] Table 1
[0076]
[0077] As shown in Table 1 above, the specific surface area of graphene prepared by the method of the present invention is significantly increased. This is because electrolyte ions or water molecules of varying sizes in the electrolyte fill the vacancy positions between graphite layers, increasing the number of electrolyte ions between the graphite layers. During the expansion of intercalated graphite, the large amount of gas generated by decomposition and volatilization between the graphite layers results in a large bursting force, thereby enhancing the expansion effect and ultimately obtaining graphene powder with a higher specific surface area. The added re-intercalation solution slurrying and soaking process in the present invention is a reverse process of moistening the material with low moisture content and then drying it, thereby increasing the specific surface area of the graphene.
[0078] The specific surface area of graphene prepared by simple electrochemical intercalation (Comparative Example 1) is only 450 m². 2 Replacing HNO3 with H2SO4 solution (Comparative Example 2) or H3PO4 solution (Comparative Example 3) did not significantly increase the specific surface area of the prepared graphene. This is because although SO4... 2- PO4 3-It can also penetrate the interlayer of graphite, but when heated, it cannot generate explosive force or generates very little explosive force, so it has no enhancing effect on expansion. Comparative Example 4, which first underwent inorganic soaking followed by electrochemical intercalation, produced graphene with a specific surface area not significantly different from that obtained by electrochemical intercalation alone. This may be due to the presence of NO3. - The ions have a large radius and cannot penetrate between the layers of the original graphite flakes.
[0079] The inventors also adjusted the electrolysis time during the multiple electrolytic intercalation process, as follows.
[0080] Comparative Example 5
[0081] A method for preparing graphene, comprising:
[0082] Steps 1-2 are the same as in Example 1;
[0083] Step 3: Wash the collected electrolytic material with pure water to remove the surface electrolyte, and then dry it in a drying oven at 60℃ for 24 hours to obtain the graphite intercalation material;
[0084] Step 4: Using the above graphite intercalated material as raw material, perform electrochemical intercalation again according to steps 1-2 (voltage of 5V, current of 44A, and time of 3h). Dry the intercalated material according to step 3.
[0085] Step 5: Weigh 0.3000g (±0.0050g) of the dried graphite intercalation material, place it in a muffle furnace, heat at 360℃ for 1min, and cool to room temperature to obtain graphene.
[0086] Comparative Example 6
[0087] A method for preparing graphene, comprising:
[0088] Steps 1-2 are the same as in Example 1;
[0089] Step 3: Wash the collected electrolytic material with pure water to remove the surface electrolyte, and then dry it in a drying oven at 60℃ for 24 hours to obtain the graphite intercalation material;
[0090] Step 4: Using the above graphite intercalated material as raw material, perform electrochemical intercalation again according to steps 1-2 (voltage of 5V, current of 44A, and time of 4h). Dry the intercalated material according to step 3.
[0091] Step 5: Weigh 0.3000g (±0.0050g) of the dried graphite intercalation material, place it in a muffle furnace, heat at 360℃ for 1min, and cool to room temperature to obtain graphene.
[0092] Comparative Example 7
[0093] A method for preparing graphene, comprising:
[0094] Steps 1-2 are the same as in Example 1;
[0095] Step 3: Wash the collected electrolytic material with pure water to remove the surface electrolyte, and then dry it in a drying oven at 60℃ for 24 hours to obtain the graphite intercalation material;
[0096] Step 4: Using the above graphite intercalated material as raw material, perform electrochemical intercalation again according to steps 1-2 (voltage of 5V, current of 44A, and time of 5h). The intercalated material is then dried according to step 3.
[0097] Step 5: Weigh 0.3000g (±0.0050g) of the dried graphite intercalation material, place it in a muffle furnace, heat at 360℃ for 1min, and cool to room temperature to obtain graphene.
[0098] Comparative Example 8
[0099] A method for preparing graphene, comprising:
[0100] Steps 1-2 are the same as in Example 1;
[0101] Step 3: Wash the collected electrolytic material with pure water to remove the surface electrolyte, and then dry it in a drying oven at 60℃ for 24 hours to obtain the graphite intercalation material;
[0102] Step 4: Using the above graphite intercalated material as raw material, perform electrochemical intercalation again according to steps 1-2 (voltage of 5V, current of 44A, and time of 4h). Dry the intercalated material according to step 3.
[0103] Step 5: Using the material dried in Step 4 as raw material, electrochemical intercalation is performed again according to Step 1-2 (voltage is 5V, current is 44A, and time is 3h). The intercalated material is then dried according to Step 3.
[0104] Step 6: Weigh 0.3000g (±0.0050g) of the dried graphite intercalation material, place it in a muffle furnace, heat at 360℃ for 1min, and cool to room temperature to obtain graphene.
[0105] Comparative Example 9
[0106] A method for preparing graphene, comprising:
[0107] Steps 1-2 are the same as in Example 1;
[0108] Step 3: Wash the collected electrolytic material with pure water to remove the surface electrolyte, and then dry it in a drying oven at 60℃ for 24 hours to obtain the graphite intercalation material;
[0109] Step 4: Using the above graphite intercalated material as raw material, perform electrochemical intercalation again according to steps 1-2 (voltage of 5V, current of 44A, and time of 4h). Dry the intercalated material according to step 3.
[0110] Step 5: Using the material dried in Step 4 as raw material, electrochemical intercalation is performed again according to Step 1-2 (voltage is 5V, current is 44A, and time is 4h). The intercalated material is then dried according to Step 3.
[0111] Step 6: Weigh 0.3000g (±0.0050g) of the dried graphite intercalation material, place it in a muffle furnace, heat at 360℃ for 1min, and cool to room temperature to obtain graphene.
[0112] Comparative Example 10
[0113] A method for preparing graphene, comprising:
[0114] Steps 1-2 are the same as in Example 1;
[0115] Step 3: Wash the collected electrolytic material with pure water to remove the surface electrolyte, and then dry it in a drying oven at 60℃ for 24 hours to obtain the graphite intercalation material;
[0116] Step 4: Using the above graphite intercalated material as raw material, perform electrochemical intercalation again according to steps 1-2 (voltage of 5V, current of 44A, and time of 4h). Dry the intercalated material according to step 3.
[0117] Step 5: Using the material dried in Step 4 as raw material, electrochemical intercalation is performed again according to Step 1-2 (voltage is 5V, current is 44A, and time is 5h). The intercalated material is then dried according to Step 3.
[0118] Step 6: Weigh 0.3000g (±0.0050g) of the dried graphite intercalation material, place it in a muffle furnace, heat at 360℃ for 1min, and cool to room temperature to obtain graphene.
[0119] The specific surface area of the graphene prepared in Comparative Examples 5-10 was measured, and the results are shown in Table 2 below.
[0120] Table 2
[0121]
[0122] Table 2 shows that the specific surface area of graphene prepared after single electrochemical intercalation, double intercalation (Comparative Examples 5-7), and triple intercalation (Comparative Examples 8-10) is not significantly different. This may be because after the first electrolysis, the particle size of the electrolytic material is smaller than that of flake graphite (see Table 3), and the density of the material layer is greater than during the first electrolysis, making it more difficult for electrolyte ions to intercalate between the graphite layers. Furthermore, the conductivity of the electrolytic material weakens after the first electrolysis, and the resistance of the material layer increases, leading to a slower migration rate of electrolyte ions. Extending the electrolysis time for multiple electrochemical intercalations has little effect on the specific surface area of the prepared graphene. This is mainly because the increased electrolysis time gradually reduces the moisture content in the electrolytic material, decreasing the fluidity of the electrolyte ions.
[0123] Table 3
[0124]
[0125] In summary, the specific surface area of graphene obtained by this invention is significantly improved. When the electrolytic material is uniformly mixed and fully contacted with different reintercalation solutions, the specific surface area of the graphene powder prepared from the resulting graphite intercalation material is significantly increased.
[0126] The above description represents the preferred embodiments of the present invention. For those skilled in the art, any improvements and modifications made without departing from the principles described herein should also be considered within the scope of protection of the present invention.
Claims
1. A method for increasing the specific surface area of electrochemically produced graphene, characterized in that, include: Step 1: Fill the material cavity between the ion exchange membrane and the anode plate with graphite flakes and squeeze them tightly to form an electrolysis unit; Step 2: Intercalate graphite using an electrochemical method. After electrolysis, collect the graphite electrolytic material. The electrolyte used in the electrolysis process is a mixture of perchloric acid solution and hydrochloric acid solution with a mass ratio of 5:1; the concentration of the perchloric acid solution is 30~40wt%, and the concentration of the hydrochloric acid solution is 15~20wt%. Step 3: Weigh the reintercalation solution, then add the graphite electrolytic material from Step 2 to it, stir evenly, and soak for a period of time; the reintercalation solution is HNO3 solution and / or HClO4 solution; the mass ratio of the reintercalation solution to the graphite electrolytic material is 10:1; the concentration of the HNO3 solution is 50 wt%; the concentration of the HClO4 solution is 50 wt%. Step 4: After multiple centrifugal washings to neutrality, the graphite intercalation material is obtained by drying. Step 5: The graphite intercalation material is subjected to a high-temperature environment for expansion treatment to obtain graphene with a specific surface area of 600-646 m² / g.
2. The method according to claim 1, characterized in that, In step 1, the graphite flakes are 150 mesh; the packing density of the graphite flakes is 2 g / cm³. 3 .
3. The method according to claim 1, characterized in that, In step 2, the electrolysis voltage is 5V, the current is 44A, and the energizing time is 4h.
4. The method according to claim 1, characterized in that, In step 3, the soaking time is 1 hour.
5. The method according to claim 1, characterized in that, In step 4, the centrifugation speed is 2000 rpm and the time is 5 min; remove the supernatant, add deionized water, and centrifuge again until the supernatant is neutral.
6. The method according to claim 5, characterized in that, In step 4, the drying temperature is 60℃ and the drying time is 24h.
7. The method according to claim 1, characterized in that, In step 5, the high-temperature environment is 360°C, with a nitrogen atmosphere, and the time is 1 minute.