Preparation method of bio-carbon-coated silicon-oxygen negative electrode material

Abstract

The application belongs to the field of new energy and new materials, and particularly relates to a preparation method of a biological carbon-coated SiOx / C negative electrode material. The application is to solve the problem of poor conductivity of SiOx / C material and the adverse effects caused by volume expansion in electrochemical cycles. The method is to uniformly synthesize SiOx / C material in porous bamboo charcoal by using terephthaldehyde and 3-aminopropyl triethoxysilane as raw materials. In the calcination process, the excess terephthaldehyde is carbonized and coated on the surface of SiOx / C to enhance the conductivity. The porous bamboo charcoal is used as a carrier to limit the volume expansion of the material, prevent the pulverization and shedding caused by excessive expansion, enhance the long cycle and high rate electrochemical performance of the SiOx / C material, and better apply the SiOx / C material in lithium ion batteries. The application is suitable for battery-grade SiOx / C material.

Description

Technical Field

[0001] This invention belongs to the field of new energy and new materials, specifically relating to a method for preparing a bio-carbon coated silicon-oxygen anode material. Background Technology

[0002] The rapid development of lithium batteries in recent years, coupled with evolving consumer demands for energy density, has made the development of new materials imperative. On May 21, 2022, Tesla's 4680 cylindrical battery, explicitly featuring a silicon-based anode, sparked a new wave of silicon-based anode industrialization. Silicon (Si), as the primary anode material, boasts an extremely high theoretical specific capacity (3580 mAh g / g). -1 and a lower lithium plating potential (0.4V Li / Li) + While silicon (Si) can significantly improve the energy density of lithium-ion batteries, the massive volume change of over 400% during alloying / dealloying leads to cracking, pulverization, and spalling of Si-based anodes, ultimately resulting in severe capacity degradation and significantly hindering their practical application in lithium-ion batteries. Therefore, there is an urgent need to explore a novel, template-free synthesis method to obtain optimal SiOx / C hollow composite materials that uniformly disperse carbon and SiOx components at the superscale, achieving high lithium-ion storage performance. Summary of the Invention

[0003] This invention aims to address the problems of poor conductivity and adverse effects of volume expansion during electrochemical cycling of silicon-oxygen materials by providing a method for preparing bio-carbon-coated silicon-oxygen anode materials.

[0004] The preparation method of the bio-carbon coated silicon-oxygen anode material of the present invention is carried out according to the following steps:

[0005] 1. Cut fresh bamboo into bamboo sections, dry them in an oven, then calcine them, ball mill them, and sieve them to obtain bamboo charcoal powder;

[0006] 2. Disperse bamboo charcoal powder in deionized water, then add aldehydes to the deionized water, and heat in a water bath to obtain a reaction solution; the mass ratio of bamboo charcoal powder to deionized water is 1g:(33~2000)mL; the mass ratio of bamboo charcoal powder to aldehydes is 1:0.05~12.

[0007] 3. Add 3-aminopropyltriethoxysilane to the reaction solution and continue the reaction. After the reaction is completed, filter and wash the product. The volume ratio of 3-aminopropyltriethoxysilane to deionized water is 1:33 to 2000.

[0008] Fourth, the product is dried and calcined to obtain bio-carbon coated silicon-oxygen anode material.

[0009] The beneficial effects of this invention are:

[0010] This invention prepares porous bamboo charcoal materials from fresh bamboo. In the pores of the bamboo charcoal material, terephthalaldehyde and 3-aminopropyltriethoxysilane undergo a dehydration condensation reaction, followed by high-temperature calcination to generate nano-SiOx materials in situ. The prepared SiOx materials can uniformly adhere to the pores of the bamboo charcoal, with a particle size of approximately 50 nm. Nanomaterials are more conducive to enhancing their electrochemical performance. Bamboo charcoal materials not only enhance the conductivity of SiOx materials, but also, during battery cycling, the pores of the bamboo charcoal limit the volume expansion of SiOx, greatly improving the long-cycle performance and rate cycling performance of SiOx materials. The nano-SiOx prepared by this invention using a liquid-phase method is suitable for lithium-ion battery anode materials, and its combination with bamboo charcoal enhances battery cycle performance. Attached Figure Description

[0011] Figure 1 This is a SEM image of the nano-silicon oxide material prepared in control group 1 of this invention;

[0012] Figure 2 This is a battery cycle diagram of the nano-silicon-oxygen material prepared in control group 1 of this invention;

[0013] Figure 3 This is a SEM image of the nano-silicon oxide material prepared in Example 1 of this invention;

[0014] Figure 4 This is a battery cycle diagram of the nano-silicon-oxygen material prepared in Example 1 of this invention. Detailed Implementation

[0015] Specific Implementation Method 1: The preparation method of a bio-carbon coated silicon-oxygen anode material in this implementation method is carried out according to the following steps:

[0016] 1. Cut fresh bamboo into bamboo sections, dry them in an oven, then calcine them, ball mill them, and sieve them to obtain bamboo charcoal powder;

[0017] 2. Disperse bamboo charcoal powder in deionized water, then add aldehydes to the deionized water, and heat in a water bath to obtain a reaction solution; the mass ratio of bamboo charcoal powder to deionized water is 1g:(33~2000)mL; the mass ratio of bamboo charcoal powder to aldehydes is 1:0.05~12.

[0018] 3. Add 3-aminopropyltriethoxysilane to the reaction solution and continue the reaction. After the reaction is completed, filter and wash the product. The volume ratio of 3-aminopropyltriethoxysilane to deionized water is 1:33 to 2000.

[0019] Fourth, the product is dried and calcined to obtain bio-carbon coated silicon-oxygen anode material.

[0020] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the oven temperature in step one is 100℃ and the time is 2 hours. Other steps and parameters are the same as in Specific Implementation Method One.

[0021] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 in that the calcination atmosphere in step one is nitrogen, argon, or a combination of nitrogen and argon; the calcination temperature is 700–900℃, and the time is 2–8 hours. Other steps and parameters are the same as in Specific Implementation Method 1.

[0022] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that the ball milling speed in step one is 200–400 rpm, the time is 2–8 hours, and the sieve mesh size is 200–500 mesh. Other steps and parameters are the same as in Specific Implementation Method One.

[0023] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that the dispersion in step two is ultrasonic dispersion, with a time of 10–60 minutes. Other steps and parameters are the same as in Specific Implementation Method One.

[0024] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method One in that: in step two, the mass of bamboo charcoal powder is 0.5g, and the volume of deionized water is 200mL; in step two, the mass of aldehyde is 1g. Other steps and parameters are the same as in Specific Implementation Method One.

[0025] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method One in that the aldehyde in step two is terephthalaldehyde or glutaraldehyde. Other steps and parameters are the same as in Specific Implementation Method One.

[0026] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method One in that the water bath temperature in step two is 50–80°C, and the heating time is 0.5–2 hours. Other steps and parameters are the same as in Specific Implementation Method One.

[0027] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method One in that the mass of 3-aminopropyltriethoxysilane in step three is 1 mL, and the reaction time is 0.5–2 h. Other steps and parameters are the same as in Specific Implementation Method One.

[0028] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method One in that the calcination temperature in step four is 700–900°C, and the time is 2–8 hours. Other steps and parameters are the same as in Specific Implementation Method One.

[0029] The beneficial effects of the present invention are verified using the following embodiments:

[0030] Example 1: A method for preparing a bio-carbon coated silicon-oxygen anode material is carried out according to the following steps:

[0031] 1. Fresh bamboo is cut into bamboo sections, dried in an oven, then calcined, ball-milled, and passed through a 200-mesh sieve to obtain bamboo charcoal powder; the calcination atmosphere is nitrogen; the calcination temperature is 800℃, and the calcination time is 6 hours.

[0032] 2. Disperse 0.5g of bamboo charcoal powder in 200mL of deionized water, then add 1g of terephthalaldehyde to the deionized water, and heat in a water bath to obtain a reaction solution; the water bath temperature is 80℃, and the heating time is 2h.

[0033] 3. Add 1 mL of 3-aminopropyltriethoxysilane to the reaction solution and continue the reaction for 2 hours. After the reaction is completed, filter and wash the product. The volume ratio of 3-aminopropyltriethoxysilane to deionized water is 1:33 to 2000.

[0034] 4. The product is dried and calcined to obtain bio-carbon coated silicon-oxygen anode material. The bio-carbon coated silicon-oxygen anode material is used to prepare electrode sheets and assemble batteries. The calcination atmosphere is nitrogen and the calcination temperature is 800℃.

[0035] Example 2:

[0036] The difference between this embodiment and Embodiment 1 is that the bamboo charcoal content in step two is 1g.

[0037] Example 3:

[0038] The difference between this embodiment and Embodiment 1 is that the calcination temperature in step four is 700°C.

[0039] Control group 1:

[0040] The difference between this embodiment and Embodiment 1 is that bamboo charcoal is not added in step two.

[0041] Control group 2:

[0042] The difference between this embodiment and control group 1 is that the mass of terephthalaldehyde in step two is 0.5g.

[0043] Control group 3:

[0044] The difference between this embodiment and control group 1 is that the mass of 3-aminopropyltriethoxysilane in step three is 2 mL.

[0045] result:

[0046] In control group 1, SiOx material was generated directly from the reaction of terephthalaldehyde and 3-aminopropyltriethoxysilane without using bamboo charcoal as a support. For example... Figure 1 The scanning electron microscope images show that the material prepared by the liquid phase method has a nanostructure, and the particles are spherical and relatively uniform in size.

[0047] Its electrochemical performance is as follows Figure 2 The coulombic efficiency of the first cycle was 50%, and the discharge specific capacity difference between the first and second cycles was 301.47 mAh g. -1 The subsequent cycles were relatively stable, and the discharge capacity retention rate was 94.3% after 100 cycles.

[0048] In control group 2, the SiOx material prepared was similar in size and shape to that in control group 1, but the yield was only 63%.

[0049] In control group 3, the SiOx material prepared was similar in size and shape to that in control group 1, but the yield was only 70%.

[0050] In Example 1, terephthalaldehyde and 3-aminopropyltriethoxysilane were reacted as raw materials to generate SiOx. The remaining terephthalaldehyde from the reaction was calcined at high temperature to generate carbon, which coated the surface of the SiOx, increasing its conductivity. Figure 4 As shown, it is uniform in size, with a dimension of 50 nm. Moreover, it innovatively uses porous bamboo charcoal as a support to generate SiOx / C material in the pores.

[0051] During the lithium insertion / extraction process, SiOx expands under restricted pressure within the pores of bamboo charcoal, enhancing the material's cycle stability. The initial cycle capacity is 767.71 mAh g. -1 The capacity was 80% higher than that of the control group (1). This indicates that the porosity of bamboo charcoal effectively inhibits the volume expansion of SiOx. The capacity after 100 cycles was 443.41 mAh g. -1 The conductivity was improved by 13.7% compared to the control group 1. This indicates that the carbon generated by terephthalaldehyde uniformly coats the SiOx surface and is generated in the pores of bamboo charcoal, which greatly improves the conductivity of the material. Moreover, the pores of bamboo charcoal can further hinder the volume expansion of SiOx during lithium insertion and extraction, reducing pulverization, peeling and other issues.

[0052] In Example 2, increasing the bamboo charcoal content resulted in a decrease in the specific capacity of the prepared SiOx / C, because the theoretical specific capacity of bamboo charcoal is 140 mAh g. -1 The theoretical specific capacity of SiOx is 2200-3580 mAh g. -1 Too high a bamboo charcoal content is not conducive to increasing mass energy density.

[0053] In Example 3, the calcination temperature was reduced to 700℃. Lowering the calcination temperature can save production costs, but 700℃ cannot completely carbonize terephthalaldehyde, and the degree of carbonization with bamboo charcoal is not high.

Claims

1. A method for preparing a bio-carbon-coated silicon-oxygen anode material, characterized in that... The preparation method of bio-carbon coated silicon-oxygen anode material is carried out according to the following steps:

1. Cut fresh bamboo into bamboo sections, dry them in an oven, then calcine them, ball mill them, and sieve them to obtain bamboo charcoal powder; 2. Disperse bamboo charcoal powder in deionized water, then add aldehydes to the deionized water, and heat in a water bath to obtain a reaction solution; the mass ratio of bamboo charcoal powder to deionized water is 1g:(33~2000)mL; the mass ratio of bamboo charcoal powder to aldehydes is 1:0.05~12.

3. Add 3-aminopropyltriethoxysilane to the reaction solution and continue the reaction. After the reaction is completed, filter and wash the product. The volume ratio of 3-aminopropyltriethoxysilane to deionized water is 1:33 to 2000. Fourth, the product is dried and calcined to obtain bio-carbon coated silicon-oxygen anode material.

2. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step one, the oven temperature is 100℃ and the time is 2 hours.

3. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step one, the calcination atmosphere is nitrogen, argon, or a combination of nitrogen and argon; the calcination temperature is 700–900℃ and the time is 2–8 hours.

4. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step one, the ball milling speed is 200-400 rpm, the time is 2-8 hours, and the sieve mesh size is 200-500 mesh.

5. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step two, the dispersion is performed by ultrasonic dispersion for 10–60 minutes.

6. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step two, the mass of bamboo charcoal powder is 0.5g, and the volume of deionized water is 200mL; the mass of aldehydes in step two is 1g.

7. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step two, the aldehydes are terephthalaldehyde or glutaraldehyde.

8. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step two, the water bath temperature is 50–80℃, and the heating time is 0.5–2 hours.

9. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step three, the mass of 3-aminopropyltriethoxysilane is 1 mL, and the reaction time is 0.5–2 h.

10. The method for preparing a bio-carbon-coated silicon-oxygen anode material according to claim 1, characterized in that... In step four, the calcination temperature is 700–900℃ and the time is 2–8 hours.

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