A preparation method of silicon-carbon electrode material and silicon-carbon electrode material and application thereof

Abstract

The present invention belongs to the field of electrode material preparation, and relates to a method for preparing a silicon-carbon electrode material, and its silicon-carbon electrode material and application. The method for preparing a silicon-carbon electrode material provided by the present invention comprises the following steps: S1, cutting and crushing retired fan blades, and screening to obtain blade powder; S2, acid-washing the blade powder, filtering, washing, and drying to obtain purified blade powder; S3, pyrolyzing the purified blade powder to obtain blade pyrolysis carbon powder; S4, vacuum Joule heating the blade pyrolysis carbon powder to obtain a solid product; S5, ball milling and screening the solid product to obtain a silicon-carbon electrode material, selecting a specific Joule heating temperature and time, etc., while recovering the silicon source and carbon source in the retired fan blades, converting them into silicon-carbon electrode materials, obtaining a high-value-added recycled product, improving the resource value, and the overall process is simple and efficient, with good application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of electrode material preparation, and in particular relates to a preparation method of a silicon-carbon electrode material and the silicon-carbon electrode material and application thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] The wind power industry is booming, and the retirement of older wind turbine blades is in full swing. Efficiently recycling and repurposing spent wind turbine blades has become a key issue impacting the wind power industry's green, circular development and low-carbon footprint goals. Wind turbine blades are primarily made of glass fiber reinforced plastic (GFRP) with an organic resin matrix. Current recycling methods for retired wind turbine blades include machining, direct landfilling, chemical dissolution, incineration, and pyrolysis. However, these methods are generally subject to high recycling costs, low product value, and significant environmental risks. Consequently, there is an urgent need to develop a new generation of recycling technologies that are both efficient, economical, and environmentally friendly.

[0004] Silicon-carbon composites, due to their unique structural design, exhibit excellent cycling stability, low expansion rate, and high specific capacity, making them a key research and development focus for lithium-ion battery anode materials. Wind turbine blades contain a rich source of silicon (glass fiber, 20%-30% SiO2) and carbon (matrix resin). Converting these abundant silicon and carbon sources from retired wind turbine blades into high-performance silicon-carbon composites would not only solve the blade recycling challenge but also provide the battery industry with a low-cost, sustainable electrode raw material, achieving the dual goals of "recycling solid waste" and "improving the quality of materials." Summary of the Invention

[0005] The present invention aims to provide a method for preparing a silicon-carbon electrode material, as well as its application. The method of the present invention can convert retired wind turbine blades into silicon-carbon electrode material, resolving the existing issues of high recycling costs, low product value, and significant environmental risks associated with retired wind turbine blades.

[0006] In order to achieve the above objectives, the present invention provides the following solutions:

[0007] In a first aspect, the present invention provides a method for preparing a silicon-carbon electrode material, comprising the following steps:

[0008] S1. Cut and crush the retired wind turbine blades, and sieve them to obtain blade powder;

[0009] S2, acid-washing the leaf powder, filtering, washing, and drying to obtain purified leaf powder;

[0010] S3. pyrolyzing the purified leaf powder to obtain leaf pyrolysis carbon powder;

[0011] S4, performing vacuum Joule heating on the blade pyrolysis carbon powder to obtain a solid product;

[0012] S5. The solid product is subjected to ball milling and screening treatment to obtain a silicon-carbon electrode material.

[0013] In one or more embodiments, in step S1, the retired fan blades are cut into a size of ≤10 cm, and the crushing and screening particle size ranges from 50 to 200 mesh. The above crushing and screening particle size can ensure uniform heat and mass transfer in subsequent reactions.

[0014] In one or more embodiments, in step S2, the acid is selected from any one of hydrochloric acid, sulfuric acid, and nitric acid; preferably, hydrochloric acid, and the concentration of the acid solution is in the range of 1 to 3 mol / L; the solid-liquid mass ratio during the pickling process is 1:5 to 1:10, and stirring is performed at room temperature for 2 to 8 hours; the drying temperature is 80 to 100° C., and the drying time is 12 to 24 hours.

[0015] The pickling process can effectively remove metal impurities such as calcium, magnesium, aluminum, and iron from the fan blades, and the above-mentioned pickling conditions can effectively avoid the corrosion loss of glass fiber and excessive wastewater treatment load; the above-mentioned drying conditions can ensure that the moisture in the raw materials is fully removed and the energy consumption is low.

[0016] In one or more embodiments, in step S3, the pyrolysis atmosphere can be one or a mixture of nitrogen, argon, carbon dioxide, and helium. The pyrolysis heating rate is 5-20°C / min, the pyrolysis temperature is 600-900°C, the holding time is 0.5-2 hours, and the gas flow rate is 50-200 mL / min. When the temperature and holding time are below the above ranges, or the heating rate is above the above ranges, the release of volatiles is insufficient, resulting in poor electrical conductivity and an underdeveloped pore structure in the pyrolytic carbon. Conversely, the pores in the carbon matrix may close or collapse, increasing energy consumption.

[0017] In one or more embodiments, in step S4, the Joule heating temperature range is 1400-1800°C, the power-on time is 10-60 seconds, and the vacuum degree is 10 -2 -10 -3 By controlling these parameters, the relative contents of SiO2, SiC, and Si, particle size, and the pore structure, degree of graphitization, and grain size of the carbon matrix can be regulated. When the temperature and power-on time exceed the upper limit, electrode ablation occurs, and silicon particles melt, agglomerate, or evaporate and lose. Conversely, SiO2 cannot undergo carbothermal reduction, resulting in a low degree of graphitization of the carbon matrix. A vacuum environment can inhibit oxidation reactions and promote carbothermal reduction reactions.

[0018] In one or more embodiments, in step S5, the ball milling speed is 400-600 rpm, the ball milling time is 4-8 hours, and then the slurry is sieved to 300-600 mesh. Too low a ball milling speed and time may result in particle size that cannot meet electrode coating requirements, while too high a ball milling speed and time may result in overly fine particles, increase slurry viscosity, reduce coating efficiency, and increase energy consumption.

[0019] In a second aspect, a silicon-carbon electrode material is prepared by the method described in the first aspect of the present invention.

[0020] In a third aspect, a use of the silicon-carbon electrode material described in the second aspect of the present invention in a lithium-ion battery or a sodium-ion battery.

[0021] The beneficial effects of the present invention are:

[0022] 1. The present invention recovers the silicon source and carbon source in the retired fan blades through a series of operations such as crushing, screening, pickling, pyrolysis, vacuum Joule heating, and ball milling, and converts them into silicon-carbon electrode materials, thereby obtaining recycled products with higher added value and improving the resource value. The overall process is simple and efficient, and has good application prospects.

[0023] 2. The vacuum rapid Joule heating method used in the present invention can heat the blade powder to an ultra-high temperature in a very short time, prompting the SiO2 in the matrix to undergo a carbon thermal reduction reaction to generate nano-silicon particles or silicon carbide, while the amorphous carbon is converted into graphitized carbon and serves as a conductive coating for the silicon particles. In addition, the ultra-high heating and cooling rate can inhibit the melting and agglomeration of silicon particles; further ball milling and screening of the solid product can ensure the acquisition of uniform nano-scale silicon-carbon electrode materials.

[0024] 3. The silicon-carbon electrode material prepared in the present invention is a composite structure of graphite carbon layers wrapped with nanoparticles, with adjustable particle size, high specific surface area, high specific capacity, cycle stability and excellent rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 A flow chart of a method for preparing silicon-carbon electrode materials from retired wind turbine blades according to Example 1 of the present invention;

[0027] Figure 2 This is a microscopic morphology of the silicon-carbon electrode material prepared in Example 1 of the present invention;

[0028] Figure 3This is a microscopic morphology of the silicon-carbon electrode material prepared in Example 2 of the present invention;

[0029] Figure 4 The first charge-discharge curves of the silicon-carbon electrode materials prepared in Examples 1-4 and Comparative Examples 1-2 of the present invention at 0.1C are shown;

[0030] Figure 5 This is a rate performance test diagram of the silicon-carbon electrode materials prepared in Examples 1-4 and Comparative Examples 1-2 of the present invention;

[0031] Figure 6 This is a performance test chart of 200 cycles of silicon-carbon electrode materials prepared in Examples 1-4 of the present invention and Comparative Examples 1-2 at 0.5C. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0033] The technical solution of the present invention is further described below with reference to specific embodiments.

[0034] Example 1

[0035] S1. Cut, crush, and screen the retired fan blades to obtain blade powder. Specifically, the retired fan blades are cut to a size of ≤10 cm, and the crushing and screening particle size range is 200 mesh.

[0036] S2. Immerse the leaf powder in a dilute hydrochloric acid solution and stir at room temperature to remove metal impurities in the raw material. The powder is then filtered, washed, and dried to obtain a purified leaf powder. Specifically, the hydrochloric acid solution has a concentration range of 1 mol / L, a solid-to-liquid mass ratio of 1:10, is stirred at room temperature for 2 hours, and is dried at 80°C for 24 hours.

[0037] S3. Slowly pyrolyze the purified leaf powder in a tube furnace to obtain leaf pyrolysis carbon powder. Specifically, the pyrolysis temperature is 900°C, the heating rate is 5°C / min, the holding time is 2 hours, and the nitrogen flow rate is 200 mL / min.

[0038] S4, vacuum Joule heating of the blade pyrolysis carbon powder to obtain a solid product. Specifically, the heating temperature is 1800 ° C, the power-on time is 10 seconds, and the vacuum degree is 10 -3 Pa.

[0039] S5. The solid product is subjected to high-speed ball milling and sieving to obtain a silicon-carbon electrode material. Specifically, the ball milling speed is 400 rpm, the ball milling time is 8 hours, and the solid product is sieved to 500 mesh.

[0040] The flow chart of the method for preparing silicon-carbon electrode materials from retired wind turbine blades in this embodiment is as follows: Figure 1 The microscopic morphology of the silicon-carbon electrode material prepared in this embodiment is shown in FIG. Figure 2 As shown in FIG. 1 , the specific surface area of ​​the silicon-carbon electrode material prepared in this embodiment is 220.1 m 2 / g,I D / I G The material is used as the negative electrode of lithium battery. The first charge and discharge coulombic efficiency is 84% ​​at a current density of 0.1C, the discharge specific capacity is 1483 mAh / g, the 1C capacity retention rate is 90%, and the capacity retention rate after 200 cycles at 0.5C is 79.9%.

[0041] Example 2

[0042] S1. Cut, crush, and screen the retired fan blades to obtain blade powder. Specifically, the cutting size of the retired fan blades is ≤10 cm, and the crushing and screening particle size range is 100 mesh.

[0043] S2. Immerse the leaf powder in a dilute hydrochloric acid solution and stir at room temperature to remove metallic impurities. The powder is then filtered, washed, and dried to obtain a purified leaf powder. Specifically, the hydrochloric acid solution has a concentration of 3 mol / L, a solid-to-liquid ratio of 1:5, is stirred at room temperature for 8 hours, and dried at 100°C for 12 hours.

[0044] S3. Slowly pyrolyze the purified leaf powder in a tube furnace to obtain leaf pyrolysis carbon powder. Specifically, the pyrolysis temperature is 700°C, the heating rate is 5°C / min, the holding time is 1 hour, and the nitrogen flow rate is 200 mL / min.

[0045] S4, vacuum Joule heating of the blade pyrolysis carbon powder to obtain a solid product. Specifically, the heating temperature is 1600 ° C, the power-on time is 20 seconds, and the vacuum degree is 10 -3 Pa.

[0046] S5. The solid product is subjected to high-speed ball milling and sieving to obtain a silicon-carbon electrode material. Specifically, the ball milling speed is 400 rpm, the ball milling time is 4 hours, and the solid product is sieved to 400 mesh.

[0047] The micromorphology of the silicon-carbon electrode material prepared in this embodiment is shown in FIG. Figure 3 As shown in FIG. 1 , the specific surface area of ​​the silicon-carbon electrode material prepared in this embodiment is 284.5 m 2 / g,I D / I GThe material is used as the negative electrode of lithium battery. The first charge and discharge coulombic efficiency is 82% at a current density of 0.1C, the discharge specific capacity is 1569 mAh / g, the 1C capacity retention rate is 88%, and the capacity retention rate after 200 cycles at 0.5C is 70.2%.

[0048] Example 3

[0049] S1. Cut, crush, and screen the retired fan blades to obtain blade powder. Specifically, the retired fan blades are cut to a size of ≤10 cm, and the crushing and screening particle size range is 150 mesh.

[0050] S2. Immerse the leaf powder in a dilute hydrochloric acid solution and stir at room temperature to remove metallic impurities. The powder is then filtered, washed, and dried to obtain a purified leaf powder. Specifically, the hydrochloric acid solution has a concentration of 2 mol / L, a solid-to-liquid ratio of 1:8, is stirred at room temperature for 6 hours, and dried at 80°C for 24 hours.

[0051] S3. Slowly pyrolyze the purified leaf powder in a tube furnace to obtain leaf pyrolysis carbon powder. Specifically, the pyrolysis temperature is 800°C, the heating rate is 5°C / min, the holding time is 1 hour, and the nitrogen flow rate is 200 mL / min.

[0052] S4, vacuum Joule heating of the blade pyrolysis carbon powder to obtain a solid product. Specifically, the heating temperature is 1400 ° C, the power-on time is 15 seconds, and the vacuum degree is 10 -3 Pa.

[0053] S5. The solid product is subjected to high-speed ball milling and sieving to obtain a silicon-carbon electrode material. Specifically, the ball milling speed is 600 rpm, the ball milling time is 8 hours, and the solid product is sieved to 600 mesh.

[0054] The specific surface area of ​​the silicon-carbon electrode material prepared in this embodiment is 189.7 m 2 / g,I D / I G The coulombic efficiency of the first charge and discharge is 86% at a current density of 0.1C, the discharge specific capacity is 1431 mAh / g, the capacity retention rate at 1C is 93%, and the capacity retention rate after 200 cycles at 0.5C is 85.0%.

[0055] Example 4

[0056] S1. Cut, crush, and screen the retired fan blades to obtain blade powder. Specifically, the retired fan blades are cut to a size of ≤10 cm, and the crushing and screening particle size range is 200 mesh.

[0057] S2. Immerse the leaf powder in a dilute hydrochloric acid solution and stir at room temperature to remove metallic impurities. The powder is then filtered, washed, and dried to obtain a purified leaf powder. Specifically, the hydrochloric acid solution has a concentration of 2 mol / L, a solid-to-liquid ratio of 1:10, is stirred at room temperature for 4 hours, and dried at 80°C for 24 hours.

[0058] S3. Slowly pyrolyze the purified leaf powder in a tube furnace to obtain leaf pyrolysis carbon powder. Specifically, the pyrolysis temperature is 800°C, the heating rate is 5°C / min, the holding time is 1 hour, and carbon dioxide is used as the carrier gas at a flow rate of 50 mL / min.

[0059] S4, vacuum Joule heating of the blade pyrolysis carbon powder to obtain a solid product. Specifically, the heating temperature is 1600 ° C, the power-on time is 10 seconds, and the vacuum degree is 10 -3 Pa.

[0060] S5. The solid product is subjected to high-speed ball milling and sieving to obtain a silicon-carbon electrode material. Specifically, the ball milling speed is 400 rpm, the ball milling time is 8 hours, and the solid product is sieved to 500 mesh.

[0061] The specific surface area of ​​the silicon-carbon electrode material prepared in this embodiment is 386.3 m 2 / g,I D / I G The average size of silicon particles is about 170 nm. When this material is used as the negative electrode of a lithium battery, the first charge and discharge coulombic efficiency is 76% at a current density of 0.1C, the discharge specific capacity is 1514 mAh / g, the 1C capacity retention rate is 85%, and the capacity retention rate after 200 cycles at 0.5C is 80.0%.

[0062] Comparative Example 1

[0063] S1. Cut, crush, and screen the retired fan blades to obtain blade powder. Specifically, the retired fan blades are cut to a size of ≤10 cm, and the crushing and screening particle size range is 200 mesh.

[0064] S2. Immerse the leaf powder in a dilute hydrochloric acid solution and stir at room temperature to remove metal impurities in the raw material. The powder is then filtered, washed, and dried to obtain a purified leaf powder. Specifically, the hydrochloric acid solution has a concentration range of 1 mol / L, a solid-to-liquid mass ratio of 1:10, is stirred at room temperature for 2 hours, and is dried at 80°C for 24 hours.

[0065] S3. Slowly pyrolyze the purified leaf powder in a tube furnace to obtain leaf pyrolysis carbon powder. Specifically, the pyrolysis temperature is 900°C, the heating rate is 5°C / min, the holding time is 2 hours, and the nitrogen flow rate is 200 mL / min.

[0066] S4, vacuum Joule heating of the blade pyrolysis carbon powder to obtain a solid product. Specifically, the heating temperature is 1200 ° C, the power-on time is 10 seconds, and the vacuum degree is 10 -3 Pa.

[0067] S5. The solid product is subjected to high-speed ball milling and sieving to obtain a silicon-carbon electrode material. Specifically, the ball milling speed is 400 rpm, the ball milling time is 8 hours, and the solid product is sieved to 500 mesh.

[0068] The specific surface area of ​​the silicon-carbon electrode material prepared in this comparative example is 243.2 m 2 / g,I D / I G The average size of silicon particles is about 160 nm. When this material is used as the negative electrode of a lithium battery, the first charge and discharge coulombic efficiency is 70% at a current density of 0.1C, the discharge specific capacity is 853 mAh / g, the 1C capacity retention rate is 55%, and the capacity retention rate after 200 cycles at 0.5C is 67.2%.

[0069] Comparative Example 2

[0070] S1. Cut, crush, and screen the retired fan blades to obtain blade powder. Specifically, the retired fan blades are cut to a size of ≤10 cm, and the crushing and screening particle size range is 200 mesh.

[0071] S2. Immerse the leaf powder in a dilute hydrochloric acid solution and stir at room temperature to remove metal impurities in the raw material. The powder is then filtered, washed, and dried to obtain a purified leaf powder. Specifically, the hydrochloric acid solution has a concentration range of 1 mol / L, a solid-to-liquid mass ratio of 1:10, is stirred at room temperature for 2 hours, and is dried at 80°C for 24 hours.

[0072] S3. Slowly pyrolyze the purified leaf powder in a tube furnace to obtain leaf pyrolysis carbon powder. Specifically, the pyrolysis temperature is 900°C, the heating rate is 5°C / min, the holding time is 2 hours, and the nitrogen flow rate is 200 mL / min.

[0073] S4, vacuum Joule heating of the blade pyrolysis carbon powder to obtain a solid product. Specifically, the heating temperature is 2000 ° C, the power-on time is 10 seconds, and the vacuum degree is 10 -3 Pa.

[0074] S5. The solid product is subjected to high-speed ball milling and sieving to obtain a silicon-carbon electrode material. Specifically, the ball milling speed is 400 rpm, the ball milling time is 8 hours, and the solid product is sieved to 500 mesh.

[0075] The specific surface area of ​​the silicon-carbon electrode material prepared in this comparative example is 152.1m 2 / g,ID / I G The material is used as the negative electrode of lithium battery. The first charge and discharge coulombic efficiency is 65% at a current density of 0.1C, the discharge specific capacity is 1124 mAh / g, the 1C capacity retention rate is 40%, and the capacity retention rate after 200 cycles at 0.5C is 54.7%.

[0076] The first charge-discharge curves of the silicon-carbon electrode materials prepared in Examples 1-4 and Comparative Examples 1-2 at 0.1C are shown in FIG. Figure 4 As shown; the rate performance test diagram of silicon carbon electrode material is as follows Figure 5 As shown; the performance test diagram of silicon carbon electrode material at 0.5C for 200 cycles is as follows Figure 6 shown.

[0077] The effect data of Examples 1-4 and Comparative Examples 1-2 are shown in Table 1 below:

[0078] Table 1 Effect data table of various embodiments and comparative examples

[0079]

[0080] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a silicon-carbon electrode material, characterized in that: The following steps are involved: S1. Cut and crush the retired wind turbine blades, and sieve them to obtain blade powder; S2, acid-washing the leaf powder, filtering, washing and drying to obtain purified leaf powder; S3. pyrolyzing the purified leaf powder to obtain leaf pyrolysis carbon powder; S4, performing vacuum Joule heating on the blade pyrolysis carbon powder to obtain a solid product; S5. ball milling and screening the solid product to obtain a silicon-carbon electrode material; In step S3, the heating rate is 5-20°C / min, the pyrolysis temperature is 700-900°C, the holding time is 0.5-2h, and the gas flow rate is 50-200 mL / min; In step S4, the Joule heating temperature is 1400-1800°C, the power-on time is 10-60 seconds, and the vacuum degree is 10 -2 -10 -3 Pa.

2. The preparation method according to claim 1, characterized in that In the step S1, the retired fan blades are crushed and screened to a particle size range of 50-200 mesh.

3. The preparation method according to claim 1, characterized in that In step 2, the acid is selected from any one of hydrochloric acid, sulfuric acid and nitric acid.

4. The preparation method according to claim 1, characterized in that The concentration of the acid solution in step 2 is in the range of 1-3 mol / L, the solid-liquid mass ratio is 1:5-1:10, and the pickling time is 2-8 hours.

5. The preparation method according to claim 1, characterized in that In step 2, the drying temperature is 80-100° C., and the drying time is 12-24 hours.

6. The preparation method according to claim 1, characterized in that In step S3, the pyrolysis atmosphere is one or a mixture of nitrogen, argon, carbon dioxide, and helium.

7. The preparation method according to claim 1, characterized in that In step S5, the ball milling speed is 400-600 rpm, the ball milling time is 4-8 hours, and then the product is sieved to 300-600 mesh.

8. A silicon-carbon electrode material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the silicon-carbon electrode material according to claim 8 in a lithium-ion battery or a sodium-ion battery.

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