PVC-based carbon material, preparation method, application and battery thereof

Abstract

This invention discloses a PVC-based carbon material, its preparation method, applications, and batteries. The method includes: heating a solution containing PVC, PEG, urea, thiourea compounds, and citric acid at 80–300°C for 2–12 hours to obtain a precursor; then carbonizing the precursor in an inert gas atmosphere to obtain the PVC-based carbon material; wherein the mass ratio of PVC to PEG is 1:(0.3–3), the mass ratio of PVC to urea is 1:(0.05–0.3), the mass ratio of PVC to thiourea compounds is 1:(0.01–0.2), and the mass ratio of PVC to citric acid is 1:(0.05–0.2). This preparation method enables the pollution-free treatment of halogen-containing polymer waste while simultaneously preparing high-efficiency, high-rate sodium-ion battery anode materials. The preparation method has advantages such as high efficiency, environmental friendliness, greenness, and energy saving.

Description

Technical Field

[0001] This invention specifically relates to a PVC-based carbon material, its preparation method, application, and battery. Background Technology

[0002] PVC (polyvinyl chloride) is a widely used plastic material with good chemical stability, corrosion resistance, flame retardancy, and processing performance. However, the production, use, and disposal of PVC can cause environmental and health problems. PVC materials are typically disposed of in landfills, but due to their non-degradable nature, they remain in the environment for a long time, causing soil and groundwater pollution. PVC is not biodegradable under natural conditions and is difficult to recycle. Its waste, due to its high chlorine content, produces dioxins and other chlorinated organic compounds and highly corrosive HCl during incineration, making it one of the most environmentally harmful plastics.

[0003] Traditional PVC recycling strategies, such as mechanical recycling and reprocessing, have low economic added value, and the material properties deteriorate during the recycling process, making them unsustainable in terms of cost. To overcome the shortcomings of traditional recycling strategies and tap into the intrinsic value of plastic waste, it is urgent to develop high-value-added green resource utilization technologies for halogenated polymers such as PVC.

[0004] Hard carbon is a carbon material with high graphitization, high conductivity, and high stability, widely used in lithium-ion batteries, supercapacitors, fuel cells, and other fields. With the rapid development of the new energy sector and the electronics and information industry, the demand for high-performance hard carbon materials is increasing. Currently, hard carbon precursors include biomass, coal, and sugars, resulting in high raw material costs. Therefore, fully utilizing waste polymers as carbon sources will significantly reduce the raw material costs of hard carbon production. Summary of the Invention

[0005] The purpose of this invention is to provide an efficient and environmentally friendly method for the resource utilization of PVC, which solves the problems existing in the prior art by preparing high-value-added hard carbon from halogen-containing polymers such as PVC.

[0006] This invention discloses a PVC-based carbon material, its preparation method, applications, and batteries. The invention involves heating PVC and polyethylene glycol (PEG) powder under the catalysis of small molecules (urea, thiourea compounds, and citric acid) to dehalogenate and crosslink and graft, forming a pre-carbonized hard carbon-soft carbon composite precursor. The pre-carbonized carbon-containing hard carbon / soft-hard carbon-soft carbon composite precursor is then treated at high temperature to prepare a hard carbon-soft carbon composite material. In this preparation method, the small molecules have at least the following functions: (1) catalyzing the low-temperature dehalogenation reaction of PVC, leading to the pre-carbonization process of the precursor; (2) after PVC dehalogenation, with the overflow of HCl, a large number of closed slit pores and micropores are formed in the PVC-derived carbon, and the organic small molecules can be deposited in the channels, thereby reducing the pore size of the carbon material; (3) promoting the inter-chain crosslinking reaction of PVC and PEG, forming a molecular-level uniform mixture and stable precursor structure; (4) amino-rich small molecules (urea, thiourea compounds) partially graft with the carbon atoms of the PVC skeleton after dehalogenation, forming heteroatoms during the heating carbonization reaction; (5) citric acid can combine with urea and thiourea compounds through hydrogen bonds to form a eutectic solvent. Through the eutectic solvation, it helps PVC, PEG and small molecules to be uniformly dispersed at lower temperatures. Finally, the prepared hard carbon-soft carbon composite anode material has higher conductivity than existing hard carbon materials, significantly improving the first-efficiency and rate performance. This preparation method enables pollution-free treatment and high-value utilization of halogenated polymer waste, and has advantages such as high efficiency, environmental protection, greenness and energy saving.

[0007] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0008] This invention provides a method for preparing PVC-based carbon materials, which includes the following steps:

[0009] A precursor is obtained by heating a solution containing PVC, PEG, urea, thiourea compounds and citric acid at 80-300°C for 2-12 hours; the precursor is then carbonized in an inert gas atmosphere to obtain the PVC-based carbon material.

[0010] The mass ratio of PVC to PEG is 1:(0.3-3), the mass ratio of PVC to urea is 1:(0.05-0.3), the mass ratio of PVC to thiourea compound is 1:(0.01-0.2), and the mass ratio of PVC to citric acid is 1:(0.05-0.2).

[0011] In this invention, the viscosity number K value of the PVC can be 50-80, for example 62-60.

[0012] In this invention, the weight-average molecular weight (M) of the PEG is... wThe value can be 8000-20000 g / mol, for example, 10000 g / mol.

[0013] In this invention, the thiourea compound is preferably thiourea and / or aminothiourea.

[0014] In this invention, the mass ratio of PVC to PEG is, for example, 1:0.5, 1:0.7, 1:1 or 1:1.5, preferably 1:(0.75-2).

[0015] In this invention, the mass ratio of PVC to urea is, for example, 1:0.075, 1:0.1, 1:0.125 or 1:0.15, preferably 1:(0.1-0.2).

[0016] In this invention, the mass ratio of PVC to the thiourea compound is, for example, 1:0.075, 1:0.1, 1:0.15 or 1:0.2, preferably 1:(0.1-0.2).

[0017] In this invention, the mass ratio of PVC to citric acid is preferably 1:(0.08-0.15), for example 1:0.1.

[0018] In one specific implementation, the mass ratio of the PVC, the PEG, the urea, the thiourea compound, and the citric acid is 1:1:0.075:0.075:0.1, 1:0.5:0.075:0.075:0.1, 1:1:0.125:0.075:0.1, 1:1:0.075:0.15:0.1, or 1:1:0.125:0.15:0.1.

[0019] In this invention, the solvent in the "solution containing PVC, PEG, urea, thiourea compounds and citric acid" can be NMP and / or DMF.

[0020] In this invention, the total mass ratio of PVC, PEG, urea, thiourea compounds and citric acid to the volume ratio of the solvent in the solution in the "solution containing PVC, PEG, urea, thiourea compounds and citric acid" can be 0.05-0.3 g / mL, for example 0.11 g / mL, 0.12 g / mL, 0.14 g / mL, 0.15 g / mL or 0.16 g / mL.

[0021] In this invention, the preferred method for preparing the "solution containing PVC, PEG, urea, thiourea compounds, and citric acid" includes: at room temperature, first adding PVC and PEG to a solvent and stirring for 5-30 minutes, then adding urea, thiourea compounds, and citric acid and stirring for another 5-30 minutes. The room temperature is generally 15-35°C, for example, 25°C. The stirring speed is conventional in the art, preferably 200-500 rpm, for example, 300 rpm.

[0022] In this invention, according to conventional practice, the heating is generally carried out under stirring conditions. The stirring speed can be 200-500 rpm, for example, 300 rpm.

[0023] In this invention, the heating preferably includes a first stage of heating and a second stage of heating. The temperature of the first stage of heating is preferably 80-150°C, for example, 120°C. The duration of the first stage of heating is preferably 1-6 hours, for example, 2 hours. The temperature of the second stage of heating is preferably 180-300°C, for example, 200°C. The duration of the second stage of heating is preferably 1-6 hours, for example, 2 hours.

[0024] In this invention, according to conventional practice in the art, after the heating process is completed, washing and drying are generally required. The conditions for washing and drying can be conventional in the art. The solvent used for washing can be ethanol and / or water.

[0025] In this invention, according to conventional practice in the art, the carbonization is generally carried out in an inert gas atmosphere, such as argon or nitrogen.

[0026] In this invention, the carbonization temperature can be 700-1100℃, for example 700℃, 900℃ or 1000℃, preferably 900-1000℃.

[0027] In this invention, the carbonization time can be 1-20 hours, preferably 3-10 hours, for example 4 hours.

[0028] The present invention also provides a PVC-based carbon material prepared by the preparation method described above.

[0029] In this invention, the PVC-based carbon material preferably has both soft carbon and hard carbon structures.

[0030] In this invention, preferably, the PVC-based carbon material has a 50C high-rate sodium storage capacity > 220mAh / g.

[0031] The present invention also provides an application of the PVC-based carbon material as described above in a battery.

[0032] The present invention also provides a battery comprising the PVC-based carbon material as described above.

[0033] In this invention, the battery is preferably a lithium-ion battery or a sodium-ion battery.

[0034] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0035] The reagents and raw materials used in this invention are all commercially available.

[0036] The positive and progressive effects of this invention are as follows:

[0037] The preparation method of this invention utilizes the difficult-to-degrade PVC to achieve efficient dechlorination and prepare high-value-added carbon materials. By introducing PEG, thiourea and urea, high-efficiency catalytic dehalogenation and PVC-PEG grafting are achieved. Carbonization realizes a soft and hard carbon coated composite structure, which significantly improves the electrochemical performance compared with ordinary hard carbon, especially the first coulombic efficiency and 50C rate performance when storing sodium. Attached Figure Description

[0038] Figure 1 TEM image of the PVC-based carbon material prepared in Example 1;

[0039] Figure 2 The image shows a TEM image of the PVC-based carbon material prepared in Comparative Example 1. Detailed Implementation

[0040] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0041] Example 1

[0042] First, at room temperature, mix 20g of polyvinyl chloride powder (Aladdin, K62-60) and 20g of PEG (M W =10000 g / mol, Alfaea (AR) was dissolved in 300 mL of NMP and stirred at 300 rpm for 10 minutes. Then, 1.5 g of urea, 1.5 g of thiourea and 2 g of citric acid were added and stirred at 300 rpm for 10 minutes. Then, the mixture was heated at 120 °C and 200 °C and stirred at 300 rpm for 2 hours each to allow it to fully dehalogenate, crosslink and graft to form a composite precursor. After heating, the mixture was washed once with anhydrous ethanol and once with deionized water. After drying in an oven, it was carbonized in a tube furnace in high-purity argon at 5 °C / min to 800 °C and held for 4 hours before cooling to obtain the carbon material.

[0043] Example 2

[0044] Compared with Example 1, except that the PEG mass was replaced with 10g, all other parameters and conditions were the same as in Example 1.

[0045] Example 3

[0046] Compared with Example 1, the parameters and conditions are the same as in Example 1, except that the carbonization temperature is replaced with 900°C.

[0047] Example 4

[0048] Compared with Example 1, the parameters and conditions are the same as in Example 1, except that the carbonization temperature is replaced with 1000°C.

[0049] Example 5

[0050] Compared with Example 1, except that the mass of urea was replaced with 2.5g, all other parameters and conditions were the same as in Example 1.

[0051] Example 6

[0052] Compared with Example 1, except that the mass of thiourea was replaced with 3.0g, all other parameters and conditions were the same as in Example 1.

[0053] Example 7

[0054] Compared with Example 1, except that the mass of urea was replaced with 2.5g and the mass of thiourea was replaced with 3.0g, all other parameters and conditions were the same as in Example 1.

[0055] Comparative Example 1

[0056] Compared with Example 1, except that PEG was not added, all other parameters and conditions were the same as in Example 1.

[0057] Comparative Example 2

[0058] Compared with Example 1, except that urea is not added, all other parameters and conditions are the same as in Example 1.

[0059] Comparative Example 3

[0060] Compared with Example 1, except for the absence of thiourea, all other parameters and conditions are the same as in Example 1.

[0061] Comparative Example 4

[0062] Compared with Example 1, except that PEG, urea and thiourea were not added, all other parameters and conditions were the same as in Example 1.

[0063] Comparative Example 5

[0064] Compared with Example 1, except that the PEG mass was replaced with 70g, all other parameters and conditions were the same as in Example 1.

[0065] Comparative Example 6

[0066] Compared with Example 1, except that the mass of urea was replaced with 8g, all other parameters and conditions were the same as in Example 1.

[0067] Comparative Example 7

[0068] Compared with Example 1, except that the mass of thiourea was replaced with 6g, all other parameters and conditions were the same as in Example 1.

[0069] Effect Example

[0070] (1) TEM

[0071] Figure 1 TEM image of the PVC-based carbon material prepared in Example 1; Figure 2 TEM image of the PVC-based carbon material prepared in Comparative Example 1. Figure 1 and Figure 2 As can be seen from the above, the PVC-based carbon material prepared in Example 1 has both the short-range ordered graphitization structure characteristic of soft carbon and the disordered turbulent layer structure characteristic of hard carbon; while the material prepared in Comparative Example 1 only has a disordered turbulent layer structure.

[0072] (2) Electrochemical performance testing

[0073] The hard carbon materials prepared in Examples 1 to 7 and Comparative Examples 1 to 7 were subjected to half-cell tests. The test method was as follows: carbon material, superconducting carbon black (Super P), and PVDF were prepared in a mass ratio of 8:1:1, uniformly mixed using a homogenizer, and then coated onto an aluminum foil current collector. The mixture was then dried overnight in a vacuum oven at 90°C. Subsequently, the resulting electrode sheets were cut into circular battery electrode sheets with a diameter of 12 mm for later use. The average mass loading was approximately 2 mg / cm². -2 A sodium metal sheet was used as the counter electrode, a single layer of glass fiber was used as the battery separator, and nickel foam discs were added. The electrolyte was a 1M NaPF6 diethylene glycol dimethyl ether solution. Constant current charge / discharge tests were performed on a LAND CT2001A battery testing system, with a voltage range of 0.001 to 3.0V. The test results are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] Based on the above experimental results, it can be seen that the hard carbon anode material prepared by the present invention has excellent electrochemical performance, especially specific capacity and rate performance.

[0078] In Comparative Example 1, the lack of PEG as a pyrolysis precursor and the inability to form a soft-hard carbon-coated composite structure due to cross-linking resulted in poor conductivity of the carbon material, leading to poor rate performance and initial coulombic efficiency. In Comparative Example 2, the lack of urea made catalytic dehalogenation difficult to achieve at the current temperature. In Comparative Example 3, the lack of thiourea compounds reduced catalytic dehalogenation efficiency and prevented the PVC dehalogenation process from forming a composite precursor with PEG hydroxyl groups, resulting in the inability to form the desired highly conductive soft-hard carbon-coated composite structure, and a significant reduction in both initial coulombic efficiency and 50C rate performance. In Comparative Example 5, the mass ratio of PVC to PEG was not within the range of 1:(0.3-3); in Comparative Example 6, the mass ratio of PVC to urea was not within the range of 1:(0.05-0.3); and in Comparative Example 7, the mass ratio of PVC to thiourea compounds was not within the range of 1:(0.01-0.2), resulting in poor electrochemical performance.

[0079] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method of producing a PVC-based carbon material, characterized by, It includes the following steps: A precursor is obtained by heating a solution containing PVC, PEG, urea, thiourea compounds and citric acid at 80~300℃ for 2-12 hours; the precursor is then carbonized in an inert gas atmosphere to obtain the PVC-based carbon material; the thiourea compounds are thiourea and / or aminothiourea. The mass ratio of PVC to PEG is 1:(0.3-3), the mass ratio of PVC to urea is 1:(0.05-0.3), the mass ratio of PVC to thiourea compound is 1:(0.01-0.2), and the mass ratio of PVC to citric acid is 1:(0.05-0.2).

2. The method for preparing PVC-based carbon material as described in claim 1, characterized in that, The viscosity K value of the PVC is 50-80; And / or, the weight-average molecular weight of the PEG is 8000-20000 g / mol.

3. The method for preparing PVC-based carbon material as described in claim 2, characterized in that, The viscosity K value of the PVC is 62-60; And / or, the weight-average molecular weight of the PEG is 10,000 g / mol.

4. The method for preparing PVC-based carbon material as described in claim 1, characterized in that, The mass ratio of PVC to PEG is 1:0.5, 1:0.7, 1:1, or 1:1.5; And / or, the mass ratio of the PVC to the urea is 1:0.075, 1:0.1, 1:0.125, or 1:0.15; And / or, the mass ratio of the PVC to the thiourea compound is 1:0.075, 1:0.1, 1:0.15, or 1:0.2; And / or, the mass ratio of the PVC to the citric acid is 1:(0.08-0.15).

5. The method for preparing PVC-based carbon material as described in claim 4, characterized in that, The mass ratio of PVC to PEG is 1:(0.75-2). And / or, the mass ratio of the PVC to the urea is 1:(0.1-0.2). And / or, the mass ratio of the PVC to the thiourea compound is 1:(0.1-0.2); And / or, the mass ratio of the PVC to the citric acid is 1:0.

1.

6. The method for preparing PVC-based carbon material as described in claim 1, characterized in that, The solvent in the "solution containing PVC, PEG, urea, thiourea compounds and citric acid" is NMP and / or DMF; And / or, in the "solution containing PVC, PEG, urea, thiourea compounds and citric acid", the total mass of PVC, PEG, urea, thiourea compounds and citric acid to the volume ratio of the solvent in the solution is 0.05-0.2 g / mL.

7. The method for preparing PVC-based carbon material as described in claim 1, characterized in that, The preparation method of the "solution containing PVC, PEG, urea, thiourea compounds and citric acid" includes: at room temperature, first adding PVC and PEG to a solvent and stirring for 5-30 minutes, then adding urea, thiourea compounds and citric acid and stirring for 5-30 minutes.

8. The method for preparing PVC-based carbon material as described in claim 1, characterized in that, The heating includes a first stage of heating and a second stage of heating.

9. The method for preparing PVC-based carbon material as described in claim 8, characterized in that, The temperature of the first stage of heating is 80-150℃.

10. The method for preparing PVC-based carbon material as described in claim 8, characterized in that, The heating time for the first stage is 1-6 hours.

11. The method for preparing PVC-based carbon material as described in claim 8, characterized in that, The temperature of the second stage of heating is 180-300℃.

12. The method for preparing PVC-based carbon material as described in claim 8, characterized in that, The second heating period is 1-6 hours.

13. The method for preparing PVC-based carbon material as described in claim 1, characterized in that, The carbonization temperature is 700-1100℃; And / or, the carbonization time is 1-20 hours.

14. The method for preparing PVC-based carbon material as described in claim 13, characterized in that, The carbonization temperature is 900-1000℃; And / or, the carbonization time is 3-10 hours.

15. A PVC-based carbon material, characterized in that, It is prepared according to the method for preparing PVC-based carbon material according to any one of claims 1-14.

16. The application of the PVC-based carbon material as described in claim 15 in a battery.

17. A battery, characterized by It includes the PVC-based carbon material as described in claim 15.

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