Preparation method of phenolic resin-based sodium ion battery hard carbon negative electrode material

Abstract

The application belongs to the field of sodium ion batteries, and particularly relates to a preparation method of a phenolic resin-based sodium ion battery hard carbon negative electrode material. The phenolic resin-based sodium ion battery hard carbon negative electrode material is prepared by adopting a foamed phenolic resin material as a hard carbon precursor material, and through carbonization, pore adjustment and carbon deposition, and the phenolic resin-based hard carbon negative electrode material with high capacity and high initial coulomb efficiency is obtained. The application utilizes the method that carbide is burned at high temperature under inert gas to achieve large-pore shrinkage, forms the graphitization structure change of the hard carbon material, and utilizes the pore adjustment method to expand the fine pores and open the closed pores, so that the carbon atom recombination is realized.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion batteries, specifically relating to a method for preparing a hard carbon anode material for sodium-ion batteries based on phenolic resin. Background Technology

[0002] Research on sodium-ion batteries originated from the "rocking chair battery" proposed by Armand in France in 1979, starting around the same time as research on lithium-ion batteries. Due to the lack of suitable anode materials, the development of sodium-ion batteries was very slow for the next decade, even approaching a standstill. It wasn't until 2000, when researchers discovered hard carbon as a suitable anode material for sodium-ion batteries, that the development of sodium-ion batteries saw a turning point. Especially after 2010, research on sodium-ion batteries experienced explosive growth, and the industrialization process was continuously advanced. However, the selection of anode materials for sodium-ion batteries is a major challenge for commercialization. After screening, hard carbon materials have become an ideal material for commercialization due to their advantages such as large interlayer spacing, low cost, simple synthesis methods, and the possibility of using renewable resources as precursors. However, traditional biomass suffers from low carbon yield, low initial efficiency, controversial sodium storage mechanisms, and complex structures that are difficult to control precisely, affecting its practical application. There is an urgent need to find precursors with high carbon yield and low cost in industrialization. Summary of the Invention

[0003] To address the problems in the prior art, this invention provides a method for preparing a phenolic resin-based sodium-ion battery hard carbon anode material, which solves the defects of existing hard carbon anode materials. By combining carbonization, pore adjustment and carbon deposition, a hard carbon anode material with high capacity and high initial coulombic efficiency is formed.

[0004] To achieve the above technical objectives, the technical solution of the present invention is as follows:

[0005] A method for preparing a phenolic resin-based hard carbon anode material for sodium-ion batteries includes the following steps:

[0006] Step 1, Phenolic Resin Foaming Material Pulverization: The phenolic resin foaming material is screened to remove impurities, and then mechanically pulverized, demagnetized, and classified to obtain precursor powder particles; the phenolic resin foaming material comes from phenolic resin foam boards, phenolic resin insulation materials, etc.; the impurities are mud, dust, fibers, etc.; the mechanical pulverization is preferably ball milling, and the phenolic resin foaming material is made into powder with a mesh size of less than 1000 mesh; then the powder particles are demagnetized and classified so that the precursor powder particles are distributed in the range of 5-13 μm.

[0007] Step 2, High-temperature carbonization under an inert atmosphere: The pulverized phenolic resin foam material is placed in a furnace chamber and carbonized under nitrogen protection at a temperature of 800-1550℃ for 6-12 hours.

[0008] Step 3, CO2-CO mixed gas orifice adjustment: After high-temperature carbonization, a CO2-CO mixed gas is introduced into the furnace to adjust the orifice of the hard carbon precursor. The CO2 content in the mixed gas is 85%-90%, the gas is introduced for 5-30 minutes, and the orifice adjustment temperature is 550-800℃. Adding a small amount of CO to this mixed gas can effectively slow down the oxidation rate.

[0009] Step 4, Carbon Deposition: The hard carbon precursor with adjusted pore size is placed in the converter furnace liner. Under nitrogen protection, a plugging agent is introduced and the furnace temperature is maintained at 300-400℃ for adsorption. Then, the plugging agent adsorbed on the carbon material is decomposed at 800-950℃, thereby depositing pyrolytic carbon on the hard carbon material. The pore size of the hard carbon precursor is adjusted so that the diameter of the ultramicropores is mostly distributed in the range of 0.4-0.6nm. Xylene is used as the plugging agent, with a flow rate of 50-60mL / min and a pressure of 0.03-0.04MPa. The carbon deposition mainly occurs in the micropores and on the surface of the powder particles.

[0010] Step 5, Finished Phenolic Resin-Based Hard Carbon Anode Material: The obtained phenolic resin-based hard carbon anode material is tested and packaged.

[0011] Furthermore, the phenolic resin-based hard carbon anode material in step 4 is sieved and classified before testing, so that the anode material powder particle D50 is distributed at about 4-10 micrometers.

[0012] As can be seen from the above description, the present invention has the following advantages:

[0013] 1. This invention solves the defects of existing hard carbon anode materials by using carbonization and porosity adjustment to form ultra-microporous precursor materials. Through carbon deposition, the material surface is modified and improved, increasing the tap density of the material and giving it high capacity and high first coulombic efficiency.

[0014] 2. This invention utilizes the method of high-temperature calcination of carbides under inert gas to achieve large-pore shrinkage, thereby forming a graphitized structure change in hard carbon materials. Furthermore, it utilizes pore adjustment to enlarge fine pores and open closed pores, achieving carbon atom recombination.

[0015] 3. The hard carbon anode material prepared by this invention undergoes pyrolytic carbon deposition in micropores, thereby forming a structure with refined surface pores, filled internal pores, and surface modification, which improves the tap density of the material.

[0016] 4. This invention utilizes carbon dioxide gas as a pore-conditioning agent. Through an oxidation-reduction reaction, it erodes the surface of the carbonized material, while removing tar-like substances and uncarbonized materials, thus developing a well-developed microporous structure in the carbonized material. At the same time, a certain amount of carbon monoxide is added to the pore-conditioning agent, which can slow down the oxidation rate and improve the stability of the pore structure.

[0017] 5. In this invention, xylene is used as a carbon deposition material. It is cracked in the macropores of the hard carbon precursor, so that the pyrolytic carbon is deposited in the micropores and on the surface. Attached Figure Description

[0018] Figure 1 This is a process diagram for preparing the phenolic resin-based hard carbon anode material of the present invention;

[0019] Figure 2 This is a scanning electron microscope (SEM) image of the material after adjusting the pore size using a CO2 / CO mixed gas in Example 1 of this invention.

[0020] Figure 3 This is a scanning electron microscope image of the carbon-deposited material in Example 1 of the present invention;

[0021] Figure 4 This is a scanning electron microscope image of the phenolic resin-based hard carbon anode material in Example 1 of the present invention;

[0022] Figure 5 This is the capacity decay curve (0-2V, 0.1C) of the negative electrode material in coin cell in Embodiment 1 of the present invention. Detailed Implementation

[0023] Combination Figures 1 to 5 This article describes a specific embodiment of the present invention in detail, but does not limit the scope of the claims of the present invention in any way.

[0024] Example 1, such as Figure 1 As shown, a method for preparing a phenolic resin-based sodium-ion battery hard carbon anode material includes the following steps:

[0025] Step 1, Phenolic Resin Foaming Material Pulverization: The phenolic resin foaming material is screened to remove impurities, then mechanically pulverized, demagnetized, and classified to obtain precursor powder particles; the phenolic resin foaming material comes from phenolic resin foam boards; the impurities are mud, dust, fibers, etc.; the mechanical pulverization is preferably ball milling, and the phenolic resin foaming material is made into powder with a mesh size of less than 1000 mesh; then the powder particles are demagnetized and classified so that the precursor powder particles are distributed in the range of 5-13 μm.

[0026] Step 2, High-temperature carbonization under an inert atmosphere: The pulverized phenolic resin foam material is placed in a furnace chamber and carbonized under nitrogen protection at a temperature of 1400℃ for 10 hours.

[0027] Step 3, CO2 / CO mixed gas pore adjustment: After high-temperature carbonization, a CO2 / CO mixed gas is introduced into the furnace to adjust the pore size of the hard carbon precursor. The CO2 content in the mixed gas is 85%, the gas introduction time is 5 minutes, and the pore adjustment temperature is 550℃, so that the diameter of the ultramicropores is mostly distributed in the range of 0.4-0.6 nm. The scanning electron microscope image of the hard carbon precursor material after pore adjustment is shown below. Figure 2 As shown,

[0028] Step 4, Carbon Deposition: The hard carbon precursor with adjusted pore size is placed in the converter furnace liner. A plugging agent is introduced under nitrogen protection while maintaining the furnace temperature at 300℃ for adsorption. Then, the plugging agent adsorbed on the carbon material is decomposed at 800℃, thereby depositing pyrolytic carbon onto the hard carbon material. The pore size of the hard carbon precursor is adjusted so that the diameter of the ultramicropores is mostly distributed in the range of 0.4-0.6 nm. Xylene is used as the plugging agent, with a flow rate of 50 mL / min and a pressure of 0.03 MPa. Carbon deposition mainly occurs within the micropores and on the surface of the powder particles. The scanning electron microscope image of the hard carbon material after carbon deposition is shown below. Figure 3 As shown,

[0029] Step 5, Finished Phenolic Resin-Based Hard Carbon Anode Material: The obtained phenolic resin-based hard carbon anode material is screened, graded, tested, and packaged. The particle size distribution of the anode material is 3-12 micrometers, with a D50 of 4.7 micrometers and a specific surface area of ​​6.5 m². 2 / g, then testing and packaging, the scanning electron microscope image of the phenolic resin-based hard carbon anode material is as follows. Figure 4 As shown.

[0030] Example 2: A method for preparing a phenolic resin-based sodium-ion battery hard carbon anode material, comprising the following steps:

[0031] Step 1, Phenolic Resin Foaming Material Pulverization: The phenolic resin foaming material is screened to remove impurities, then mechanically pulverized, demagnetized, and classified to obtain precursor powder particles; the phenolic resin foaming material comes from phenolic resin insulation material; the impurities are mud, dust, fibers, etc.; the mechanical pulverization is ball milling, and the phenolic resin foaming material is made into powder with a mesh size of less than 1200 mesh; then the powder particles are demagnetized and classified so that the precursor powder particles are distributed in the range of 5-10 μm.

[0032] Step 2, High-temperature carbonization under an inert atmosphere: The pulverized phenolic resin foam material is placed in a furnace chamber and carbonized under nitrogen protection at a temperature of 1200℃ for 8 hours.

[0033] Step 3, CO2-CO mixed gas orifice adjustment: After high-temperature carbonization, CO2-CO mixed gas is introduced into the furnace to adjust the orifice of the hard carbon precursor. The proportion of CO2 in the mixed gas is 90%, the gas is introduced for 30 minutes, and the orifice adjustment temperature is 800℃.

[0034] Step 4, Carbon Deposition: The hard carbon precursor with adjusted pore size is placed in the converter furnace liner. A plugging agent is introduced under nitrogen protection while maintaining the furnace temperature at 300-400℃ for adsorption. Then, the plugging agent adsorbed on the carbon material is decomposed at 800-950℃, thereby depositing pyrolytic carbon onto the hard carbon material. The pore size of the hard carbon precursor is adjusted so that the diameter of the ultramicropores is mostly distributed in the range of 0.3-0.5 nm. Xylene is used as the plugging agent, with a flow rate of 60 mL / min and a pressure of 0.04 MPa. Carbon deposition mainly occurs within the micropores and on the surface of the powder particles.

[0035] Step 5, Finished Phenolic Resin-Based Hard Carbon Anode Material: The obtained phenolic resin-based hard carbon anode material is further screened and graded, with particle size distribution ranging from 4 to 15 micrometers, a D50 of 9.5 micrometers, and a specific surface area of ​​5.2 m². 2 / g, then testing and packaging.

[0036] Example 3: A method for preparing a phenolic resin-based sodium-ion battery hard carbon anode material, comprising the following steps:

[0037] Step 1, Phenolic Resin Foaming Material Pulverization: The phenolic resin foaming material is screened to remove impurities, then mechanically pulverized, demagnetized, and classified to obtain precursor powder particles; the phenolic resin foaming material comes from phenolic resin foam boards; the impurities are mud, dust, fibers, etc.; the mechanical pulverization is preferably ball milling, and the phenolic resin foaming material is made into powder with a mesh size of less than 1300 mesh; then the powder particles are demagnetized and classified so that the precursor powder particles are distributed in the range of 5-9 μm.

[0038] Step 2, High-temperature carbonization under an inert atmosphere: The pulverized phenolic resin foam material is placed in a furnace chamber and carbonized under nitrogen protection at a temperature of 1000℃ for 6 hours.

[0039] Step 3, CO2 and CO mixed gas pore adjustment: After high-temperature carbonization, CO2 and CO mixed gas is introduced into the furnace to adjust the pores of the hard carbon precursor. The proportion of CO2 in the mixed gas is 87%, the gas introduction time is 20 minutes, and the pore adjustment temperature is 700℃, so that the diameter of the ultra-micro pores is mostly distributed in the range of 0.4-0.6nm.

[0040] Step 4, Carbon Deposition: The hard carbon precursor with adjusted pore size is placed in the converter furnace liner. A plugging agent is introduced under nitrogen protection and the furnace temperature is maintained at 350℃ for adsorption. Then, the plugging agent adsorbed on the carbon material is decomposed at 850℃, thereby depositing pyrolytic carbon on the hard carbon material. The pore size of the hard carbon precursor is adjusted so that the diameter of the ultramicropores is mostly distributed in the range of 0.4-0.6nm. Xylene is used as the plugging agent, with a flow rate of 55mL / min and a pressure of 0.03MPa. The carbon deposition mainly occurs in the micropores and on the surface of the powder particles.

[0041] Step 5, Finished Phenolic Resin-Based Hard Carbon Anode Material: The obtained phenolic resin-based hard carbon anode material is screened, graded, tested, and packaged. The particle size distribution of the anode material is 2-10 micrometers, with a D50 of 6.3 micrometers and a specific surface area of ​​5.5 m². 2 / g, then testing and packaging.

[0042] Performance testing

[0043] Using the product of Example 3 as a test example, and coal-based soft carbon and biomass-based hard carbon as Comparative Examples 1 and 2, respectively, capacity tests were conducted, and their structures are as follows:

[0044]

[0045] The product of this invention has high capacity and good first coulomb efficiency, and is ready for commercialization.

[0046] The negative electrode material from Example 1 was used to form a coin cell, and the cycle life of the negative electrode material was tested and analyzed. The active material of this half-cell was: negative electrode material from Example 1 / PVDF = 90 / 10; the counter electrode was metallic sodium (Na), and the electrolyte was sodium hexafluorophosphate. After 200 cycles, the specific capacity of the material reached over 300 mAh / g, meeting the requirements for commercialization.

[0047] It is understood that the above detailed description of the present invention is for illustrative purposes only and is not intended to limit the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effects; as long as the usage requirements are met, they are all within the protection scope of the present invention.

Claims

1. A method for preparing a phenolic resin-based hard carbon anode material for sodium-ion batteries, characterized in that: Includes the following steps: Step 1, Phenolic Resin Foaming Material Crushing: The phenolic resin foaming material is screened to remove impurities, and then mechanically crushed, demagnetized, and classified to obtain precursor powder particles. Step 2, High-temperature carbonization under an inert atmosphere: The pulverized phenolic resin foam material is placed in the furnace chamber and carbonized under nitrogen protection. Step 3, CO2-CO mixed gas orifice adjustment: After high-temperature carbonization, CO2-CO mixed gas is introduced into the furnace to adjust the orifice of the hard carbon precursor. Step 4, carbon deposition: The hard carbon precursor after pore adjustment is placed in the converter furnace lining, and a pore-blocking agent is introduced under nitrogen protection while maintaining the furnace temperature at 300-400℃ for adsorption; then the pore-blocking agent adsorbed on the carbon material is decomposed at 800-950℃, thereby depositing pyrolytic carbon on the hard carbon material. Step 5, Finished Phenolic Resin-Based Hard Carbon Anode Material: The obtained phenolic resin-based hard carbon anode material is tested and packaged. The phenolic resin foaming material in step 1 comes from thermosetting phenolic resin foaming board or phenolic resin insulation material; the mechanical crushing adopts ball milling, and the phenolic resin foaming material is made into powder particles of less than 1000 mesh, and then the powder particles are demagnetized and classified so that the precursor powder particles are distributed in 5-13μm. The temperature in step 2 is 800-1550℃, and the time is 6-12 hours; The CO2 content in the mixed gas in step 3 is 85%-90%, and the gas is introduced for 5-30 minutes; the temperature of the adjusting orifice is 550-800℃. The plugging agent in step 4 is xylene, with a flow rate of 50-60 mL / min and a pressure of 0.03-0.04 MPa; the carbon deposition mainly occurs in the micropores and on the surface of the powder particles.

2. The method for preparing the phenolic resin-based sodium-ion battery hard carbon anode material according to claim 1, characterized in that: In step 4, the phenolic resin-based hard carbon anode material is sieved and classified before testing to ensure that the anode material powder particle D50 is distributed at approximately 4-10 micrometers.

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