Modification method of silicon-carbon material and silicon-carbon material thereof
Plasma treatment introduces hydroxyl groups on Si/C materials to address dispersion and mixing issues, improving dispersibility and reducing mixing time, thus enhancing battery performance.
Patent Information
- Application Number
- CN202510545159.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-07-15
AI Technical Summary
Traditional CVD silicon carbon materials have shortcomings in dispersion and homogenization properties, resulting in high production costs, long time and easy damage to the material, affecting its performance.
The plasma discharge ball mill vibration device is used to treat the reaction of silicon carbon materials with hydrogen peroxide, and hydroxyl functional groups are introduced. Through the synergistic effect of plasma discharge and vibration device, the dispersion performance and homogenization time of silicon carbon materials are improved.
It significantly improves the dispersion performance and homogenization efficiency of silicon-carbon materials, shortens the preparation time, maintains the original structure and performance of the material, simplifies the preparation process, and reduces production costs.
Smart Images
Figure CN120308943A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of batteries, and in particular to a modification method of silicon-carbon materials and the silicon-carbon materials thereof.
[0002] With the continuous development of material science, the theoretical capacity of the graphite negative electrode of commercial lithium-ion batteries is only 372 mAh / g, which can no longer meet the application requirements of high-energy lithium-ion batteries. Silicon-based negative electrode materials are considered ideal alternative materials due to their wide sources and relatively high theoretical capacity (4200 mAh / g). As an important composite material, CVD silicon-carbon materials have shown great application potential in the field of battery materials. However, traditional CVD silicon-carbon materials have some limitations in practical applications. In particular, on the one hand, their dispersion performance is poor. In the process of preparing composite materials or electrode slurries, etc., the silicon-carbon materials need to be uniformly mixed with other substances. However, due to the limitations of their surface properties, it often takes a long time and a high energy input during the dispersion process to achieve an ideal effect; this not only increases the production cost and time cost, but also may cause damage to the materials due to the action of excessive shear force during the dispersion process, affecting their final performance. On the other hand, their homogenization performance is poor: in the homogenization process, traditional silicon-carbon materials take a long time to reach an ideal slurry state, and are prone to agglomeration, and problems such as damage to the materials themselves and generation of bubbles are likely to occur during the homogenization process, which to a certain extent limits the full play of their performance and the scope of practical applications. Summary of the Invention
[0004] In order to solve the technical problems existing in silicon-carbon materials in the prior art, the present invention provides a modification method of silicon-carbon materials, including the following steps: S01: Place the silicon-carbon materials and hydrogen peroxide in the cavity of a plasma discharge ball milling vibration device; S02: Introduce oxygen into the cavity of the plasma discharge ball milling vibration device; S03: Start the discharge device and vibration device in the plasma ball milling vibration device to make the silicon-carbon materials react with the hydrogen peroxide; S04: Start the cooling device in the plasma discharge ball milling vibration device to cool the silicon-carbon materials after the reaction in the above step S03 to obtain the modified silicon-carbon materials.
[0005] Further, the mass percentage of the silicon-carbon materials and hydrogen peroxide added in the step S01 is: 80~99.99%: 0.01~20%.
[0006] Further, after introducing oxygen in the step S02, the air pressure in the cavity is maintained at -0.01 MPa to 1 MPa.
[0007] Further, in step S03, the power of the discharging device is 100 - 1000 W, and the rotation speed of the vibrating device is 100 - 1000 RPM.
[0008] Further, after starting the discharging and rotating devices in step S03, the reaction time is 10 - 180 minutes.
[0009] Further, the cooling time in step S04 is 10 - 180 minutes.
[0010] Further, steps S03 and S04 are cycled three times.
[0011] Further, the hydrogen peroxide in step S01 is a liquid with a concentration of 5% - 50%.
[0012] Further, the silicon carbide material used in step S01 is one or more of silicon carbide particles and silicon carbide thin films.
[0013] Another aspect of the present invention also provides a silicon carbide material modified by the above method.
[0014] The silicon carbide material modification method provided by the present invention introduces hydroxyl functional groups on the surface of the silicon carbide material through plasma treatment of the traditional CVD silicon carbide material. The modification preparation process is simple, environmentally friendly, and efficient, significantly improving the dispersion performance of the silicon carbide material and shortening the homogenization time in the preparation process of the negative electrode slurry. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 is a flow chart of the modification method of the silicon carbide material in Example 1; Figure 2 is a SEM comparison chart of the silicon carbide material before and after being treated by the modification method in Example 1; Figure 3 is an infrared spectrum comparison chart of the silicon carbide material before and after being treated by the modification method in Example 1: Figure 4 is a thermal stability chart of the silicon carbide material after being treated by the modification method in Example 1; Figure 5 is a powder resistance comparison chart of the silicon carbide material before and after being treated by the modification method in Example 1; Figure 6 is a comparison chart of the dispersion of the silicon carbide material before and after being treated by the modification method in Example 1 in water; Figure 7 is a comparison chart of the rheological properties of the negative electrode slurry prepared from the silicon carbide material before and after being treated by the modification method in Example 1; Figure 8 is a comparison chart of the shear viscosity of the negative electrode slurry prepared from the silicon carbide material before and after being treated by the modification method in Example 1 Figure 9 The particle size distribution comparison chart of the negative electrode slurry prepared from the silicon-carbon material before and after being treated by the modification method of Example 1; Figure 10 The viscoelasticity comparison chart of the negative electrode slurry prepared from the silicon-carbon material before and after being treated by the modification method of Example 1; Figure 11 The pH value comparison chart of the negative electrode slurry prepared from the silicon-carbon material before and after being treated by the modification method of Example 1; Figure 12 The EIS comparison chart of the negative electrode plate prepared from the silicon-carbon material before and after being treated by the modification method of Example 1; Figure 13 The capacity comparison chart of the negative electrode plate prepared from the silicon-carbon material before and after being treated by the modification method of Example 1; Figure 14 The cyclic discharge capacity comparison chart of the full battery assembled with the negative electrode plate prepared from the silicon-carbon material before and after being treated by the modification method of Example 1 and a 9-series ternary positive electrode; Figure 15 The capacity retention rate comparison chart of the full battery assembled with the negative electrode plate prepared from the silicon-carbon material before and after being treated by the modification method of Example 1 and a 9-series ternary positive electrode; Figure 16 The rate performance comparison chart of the full battery assembled with the negative electrode plate prepared from the silicon-carbon material before and after being treated by the modification method of Example 1 and a 9-series ternary positive electrode. Detailed implementation manners
[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.
[0017] The embodiments of the present invention provide a modification method for silicon-carbon materials, including the following steps: S01: Place the silicon-carbon material and hydrogen peroxide in the cavity of the plasma discharge ball-milling vibration device; S02: Inject oxygen into the cavity of the plasma discharge ball-milling vibration device; S03: Start the discharge device and the vibration device in the plasma ball-milling vibration device to make the silicon-carbon material react with the hydrogen peroxide; S04: Start the cooling device in the plasma discharge ball-milling vibration device to cool the silicon-carbon material after the reaction in the above step S03 to obtain the modified silicon-carbon material.
[0018] The mass percentages of the silicon-carbon material and hydrogen peroxide added in the step S01 are: 80~99.99%: 0.01~20%.
[0019] After injecting oxygen in the step S02, the air pressure in the cavity is maintained at -0.01 MPa to 1 MPa.
[0020] In step S03, the power of the discharge device is 100 - 1000 W, and the rotation speed of the vibration device is 100 - 1000 RPM.
[0021] In step S03, the reaction time after starting the discharge and the rotation device is 10 - 180 minutes.
[0022] The cooling time of step S04 is 10 - 180 minutes.
[0023] Steps S03 and S04 are cycled three times.
[0024] The hydrogen peroxide in step S01 is a liquid with a concentration of 5% - 50%.
[0025] The silicon carbide material used in step S01 is one or more of silicon carbide particles and silicon carbide thin films.
[0026] To better understand the technical solution provided by the present invention, the following uses multiple specific examples to separately illustrate the preparation process and characteristics of the silicon carbide material of the present invention. Example 1
[0027] S01: Take 80 g of conventional CVD silicon carbide material A and 20 g of hydrogen peroxide liquid with a concentration of 10% and place them in the reaction kettle of the plasma discharge ball milling vibration device.
[0028] S02: After evacuating the reaction kettle, fill the reaction kettle with oxygen so that the substances in the reaction kettle are carried out under an oxygen environment. After evacuating and filling oxygen three times in a cycle, maintain the air pressure in the reaction kettle at -0.01 MPa to 0.1 Mpa under an oxygen atmosphere.
[0029] S03: Start the plasma discharge ball milling vibration device, set the power of the plasma discharge device to 100 - 1000 W, at the same time turn on the vibration device, set the rotation speed of the vibration motor to 100 - 1000 RPM, and set the reaction time to 30 minutes.
[0030] S04: Cool the substances processed in step S03, and the cooling time is 30 minutes.
[0031] S05: After cooling, start the plasma reaction device again and repeat steps S03 and S04 three times to obtain the silicon carbide material B after plasma treatment. Example 2
[0032] This embodiment is basically the same as the modification method of Embodiment 1. The difference is that in this embodiment, the masses of the conventional CVD silicon-carbon material A and the added hydrogen peroxide in step S01 are different. In this embodiment, the mass of the added conventional CVD silicon-carbon material A is 99.99 g, the mass of the added hydrogen peroxide solution is 0.01 g, the concentration of hydrogen peroxide is 10%, the reaction time in step S03 is 180 minutes, and the reaction time in step S04 is 60 minutes. Example 3
[0033] This embodiment is basically the same as the modification method of Embodiment 1. The difference is that in this embodiment, the masses of the conventional CVD silicon-carbon material A and the added hydrogen peroxide in step S01 are different. In this embodiment, the mass of the added conventional CVD silicon-carbon material A is 98 g, the mass of the added hydrogen peroxide solution is 2 g, the concentration of hydrogen peroxide is 30%, the reaction time in step S03 is 10 minutes, and the reaction time in step S04 is 10 minutes. Example 4
[0034] This embodiment is basically the same as the modification method of Embodiment 1. The difference is that in this embodiment, the masses of the conventional CVD silicon-carbon material A and the added hydrogen peroxide in step S01 are different. In this embodiment, the mass of the added conventional CVD silicon-carbon material A is 95 g, the mass of the added hydrogen peroxide solution is 5 g, the concentration of hydrogen peroxide is 50%, the reaction time in step S03 is 60 minutes, and the time in step S04 is 180 minutes. Comparative Example 1
[0035] This comparative example uses the same conventional CVD silicon-carbon material A as in step S01 of Embodiment 1 and does not perform any other treatment, so as to make a reference with the silicon-carbon material B obtained in Embodiment 1 and conduct corresponding performance tests.
[0036] Powder property test
[0037] Performance tests were carried out on the silicon-carbon material B (abbreviated as Plasma) after plasma treatment in Example 1 above and the original CVD silicon-carbon material A (abbreviated as blank) in the comparative example; including SEM scanning, infrared testing, powder resistance testing, and dispersion experiments in water respectively, so as to obtain the corresponding SEM scanning electron microscope images, infrared spectra, powder resistance test graphs, and dispersion effect comparison graphs. At the same time, a thermal stability test was carried out separately on the plasma-modified silicon-carbon material B obtained in Example 1 and a thermal stability performance graph was obtained; the thermal stability test mainly observed the thermal stability changes of the silicon-carbon material A after plasma treatment modification over a period of time, including the initial state, vacuum heating of the material at 120 °C for 3 h, and vacuum heating of the material at 120 °C for 12 h, and the thermal stability changes of the plasma-treated and modified silicon-carbon material B in these three states. Among them, the process of the dispersion experiment on the silicon-carbon material powder mainly included placing the powder in water for ultrasonic dispersion, and observing the dispersion of the silicon-carbon powder in water every 5 minutes.
[0038] According to the above experimental process and the corresponding experimental results, we passed Figure 2 From the SEM electron microscope images, it can be seen that for the silicon-carbon material B modified by plasma, its SEM morphology is almost unchanged from that of the conventional CVD silicon-carbon material A, indicating that this modification method can effectively introduce hydroxyl functional groups without damaging the original structure of the silicon-carbon material, so as to ensure that other properties of the silicon-carbon material are not affected and still maintain its original excellent characteristics. Through Figure 3 From the infrared test comparison graphs of the silicon-carbon material before and after plasma treatment in Figure 4 it can be seen that the hydroxyl peak of the silicon-carbon powder material after plasma treatment is significantly strengthened, indicating that the silicon-carbon material has successfully completed hydroxyl grafting. According to Figure 5 the thermal stability test of the hydroxylated silicon-carbon powder after plasma treatment in Figure 6 it can be seen that after the hydroxyl-grafted silicon-carbon material is heated at 120 °C in vacuum for 3 h and 12 h, the intensity of the hydroxyl peak does not change much and still maintains a good stable structure. According to Figure 5 From the powder resistance comparison graphs of the silicon-carbon material before and after plasma treatment in Figure 6 it can be seen that: the resistivity of the treated silicon-carbon powder only rises slightly, so the silicon-carbon material modified by plasma will not affect its application in the battery. According to Figure 6 From the dispersion comparison graphs of the silicon-carbon powder in water before and after plasma treatment in it can be seen that: when 200 mg of silicon-carbon powder material is added to 300 mL of water and ultrasonic treatment is carried out for 5, 10, and 20 min, it is found that the silicon-carbon material after plasma treatment can be evenly dispersed in water in a short time, indicating that the silicon-carbon material modified by this method can well improve its homogenization dispersion efficiency, and the homogenization time is shortened by half. Preparation of the negative electrode slurry and slurry performance testing
[0039] The corresponding silicon-carbon materials obtained in the above Example 1 and Comparative Example 1 were respectively stirred with a conductive agent and a binder to form a slurry, and the rheology, shear viscosity, particle size distribution, viscoelasticity, and pH value of the corresponding slurry were tested. Then, the prepared slurry was coated on a copper foil current collector to prepare a negative electrode sheet, and the thickness of the negative electrode sheet was controlled to be 400 μm. Then, the negative electrode sheet, electrolyte, lithium metal negative electrode, and separator were assembled into a button-type half-cell, and the impedance performance and charge-discharge capacity of the prepared button-type half-cell were tested. In addition, a 9-series ternary positive electrode was paired and assembled into a button-type full-cell, and its cycling and rate performance were tested.
[0040] According to Figures 7 - 11 As can be seen from the results shown, when the plasma-treated silicon-carbon powder was used to prepare the negative electrode slurry, the homogenization time was shortened by half, but the slurry remained basically unchanged in terms of rheology, shear viscosity, particle size distribution, viscoelasticity, and pH value, which means that the modified silicon-carbon material can effectively shorten the homogenization time, thereby avoiding material damage and gas generation problems caused by long-term homogenization, reducing material loss and defect generation, and further improving the performance and stability of the material.
[0041] According to Figures 12 - 13 It can be found that the modified silicon-carbon material slightly reduces the electrochemical impedance and significantly improves the charge capacity, which may be due to the modification of hydroxyl groups promoting the uniformity of dispersion and enhancing the wettability of the electrolyte, resulting in a decrease in battery impedance and an increase in capacity.
[0042] According to Figures 14 - 16 It can be found that the full-cell assembled with the modified silicon-carbon material and a 9-series ternary positive electrode exhibits significantly improved cycling performance and rate performance. This may also be due to the modification of hydroxyl groups promoting the uniformity of dispersion and enhancing the wettability of the electrolyte, thereby exhibiting excellent electrochemical performance. Prepare a full-cell and test the chemical performance of the full-cell
[0043] The negative electrode sheets, positive electrode sheets, and separators prepared by the methods of the above respective examples were alternately stacked in a "Z" shape. After ultrasonic welding of the positive electrode tab to an aluminum sheet and ultrasonic welding of the negative electrode tab to nickel-plated copper, it was pre-sealed with an aluminum-plastic film, and then the electrolyte was injected into the above battery and formed in a conventional manner to obtain a lithium-ion battery, and the capacity retention rate and initial efficiency of the battery were tested. The test results are shown in Table 1 below:
[0044] In the present invention, a plasma device is used to perform a synergistic action of discharging and vibrating on the silicon-carbon material to promote uniform grafting of the silicon-carbon material; compared with the unmodified silicon-carbon material, the modified silicon-carbon material has the following beneficial effects: First, excellent dispersion performance: By introducing hydroxyl functional groups on the surface of silicon-carbon materials, the dispersion performance of silicon-carbon materials is significantly improved. In the dispersion experiment, the modified silicon-carbon materials have a faster dispersion speed and better effect, which enables the achievement of an ideal mixing state more quickly during the preparation of composite materials or electrode slurries, etc., improving production efficiency and product quality.
[0045] Second, the homogenization time is shortened: During the homogenization process, the modified silicon-carbon materials only need half of the original time to complete the homogenization of silicon-carbon, and the obtained slurries are basically the same in terms of pH, rheology, particle size, viscoelastic effect, etc. The shortened homogenization time effectively improves the problems of damage and gas generation of silicon-carbon materials during homogenization, reduces material loss and the generation of defects, and further improves the performance and stability of the product.
[0046] Third, the original structure is maintained: For the modified silicon-carbon materials, their SEM morphology hardly changes, indicating that this modification method can effectively introduce hydroxyl functional groups without damaging the original structure of the materials. This ensures that the silicon-carbon materials are not affected in other performance aspects and still maintain their original excellent characteristics, such as high specific capacity, good conductivity, etc.
[0047] Fourth, the preparation method is simple and environmentally friendly. The preparation method combining plasma discharge and vibration treatment adopted in the present invention is simple to operate, easy to control, and does not cause serious environmental pollution. Plasma discharge treatment can generate a large number of active sites on the surface of silicon-carbon materials, providing favorable conditions for subsequent chemical reactions; vibration treatment helps the uniform distribution and full reaction of hydrogen peroxide on the surface of silicon-carbon materials, thus ensuring the efficient introduction of hydroxyl functional groups. The entire preparation process does not require complex equipment and cumbersome chemical reaction steps and has good industrial application prospects.
[0048] In summary, the silicon-carbon materials with a surface-modified structure and their preparation method involved in the present invention effectively solve the deficiencies of traditional silicon-carbon materials in terms of dispersibility and processing performance, providing technical support and innovative solutions for the wider application of silicon-carbon materials in the fields of high-performance electrode materials, composite materials, etc.
Claims
1. A modification method of silicon-carbon material, comprising the following steps: S01: Place the silicon-carbon material and hydrogen peroxide in the cavity of a plasma discharge ball milling vibration device; S02: Introduce oxygen into the cavity of the plasma discharge ball milling vibration device; S03: Start the discharge device and the vibration device in the plasma ball milling vibration device to make the silicon-carbon material react with the hydrogen peroxide; S04: Start the cooling device in the plasma discharge ball milling vibration device to cool the silicon-carbon material after the reaction in the above step S03 to obtain the modified silicon-carbon material.
2. The modification method of the silicon-carbon material according to claim 1, wherein, The mass percentages of the silicon-carbon material and hydrogen peroxide added in the step S01 are: 80~99.99%: 0.01~20%.
3. The modification method of the silicon carbide material according to claim 1, wherein, After introducing oxygen in the step S02, the air pressure in the cavity is maintained at -0.01MPa~1Mpa.
4. The modification method of the silicon-carbon material according to claim 1, wherein, In the step S03, the power of the discharge device is 100~1000W, and the rotation speed of the vibration device is 100~1000RPM.
5. The modification method of the silicon-carbon material according to claim 1, characterized in that, In the step S03, the reaction time after starting the discharge and the rotation device is 10~180 minutes.
6. The modification method of the silicon carbide material according to claim 1, wherein The cooling time in the step S04 is 10~180 minutes.
7. The modification method of the silicon-carbon material according to claim 1, characterized in that, The steps S03 and S04 are cycled three times.
8. The modification method of the silicon-carbon material according to claim 1, characterized in that, The hydrogen peroxide in the step S01 is a liquid with a concentration of 5%~50%.
9. The modification method of the silicon-carbon material according to claim 1, wherein The silicon-carbon material used in the step S01 is one or more of silicon-carbon particles and silicon-carbon thin films.
10. A silicon carbide material, characterized in that, Prepared by using the modification method according to any one of claims 1 to 9.