Sodium-ion battery carbon negative electrode material based on high-sulfur petroleum coke as well as preparation method and application of sodium-ion battery carbon negative electrode material

Abstract

The invention relates to a sodium-ion battery carbon negative electrode material based on high-sulfur petroleum coke and a preparation method and application thereof.The preparation method comprises the steps that a high-sulfur petroleum coke raw material is smashed into the target particle size, then in the air atmosphere, a sulfur fixing agent, an inhibitor and a surface modifier are added, after fusion granulation, gradient heating treatment, depolymerization and demagnetization are conducted, and the sodium-ion battery carbon negative electrode material is obtained; and preparing the carbon negative electrode material. Compared with the prior art, the method has the advantages that the chemical conversion process of sulfur in the high-sulfur petroleum coke can be realized, the structure of the petroleum coke is reformed, the material is endowed with rich pores, and the damage of sulfur escape to the material structure is solved. Researches show that the material prepared by the method has excellent gram volume and long cycle life.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, specifically to a sodium-ion battery carbon anode material based on high-sulfur petroleum coke, its preparation method, and its application. Background Technology

[0002] Driven by the "dual carbon" goal, new energy power generation methods such as wind and solar power have developed rapidly. However, the instability of their intermittent power generation poses a significant challenge to the power grid. Energy storage can greatly alleviate this problem, and sodium-ion batteries, as an important energy storage technology, have received considerable attention. Sodium-ion batteries mainly consist of positive electrode materials, negative electrode materials, electrolytes, separators, and current collectors. Among these, carbon-based negative electrode materials are considered the best negative electrode materials for sodium-ion batteries. Low-cost, high-performance carbon negative electrode materials are one of the factors restricting the commercial application of sodium-ion batteries. Carbon negative electrode materials can be divided into hard carbon and soft carbon. Hard carbon materials, represented by biomass and resins, have developed rapidly, but their high price greatly affects the large-scale application of sodium-ion batteries. Petroleum coke, a representative of soft carbon, is a petrochemical byproduct with characteristics such as large supply, stable output, and high consistency. It is considered a carbon source with great commercial potential for sodium-ion battery carbon negative electrode materials. Based on their sulfur content, petroleum coke can be classified into low-sulfur petroleum coke, medium-sulfur petroleum coke, and high-sulfur petroleum coke. Among them, low-sulfur petroleum coke is in high demand due to its wide range of applications. High-sulfur petroleum coke, on the other hand, is limited by its higher sulfur content and more impurities, making it unsuitable for applications requiring low-sulfur petroleum coke. Therefore, a solution is urgently needed.

[0003] Currently, there are few reports on the application of low-cost, high-sulfur petroleum coke in carbon anode materials for sodium-ion batteries. This is due to significant technical obstacles: (1) Petroleum coke is prone to graphitization at high temperatures, resulting in poor sodium ion storage capacity, thus requiring strict control of the carbonization temperature; (2) The sulfur in high-sulfur petroleum coke is mainly organic sulfur, which usually accounts for more than 90%, making its removal difficult, especially at lower carbonization temperatures; (3) Inappropriate desulfurization processes, such as chemical methods, can severely affect the structure of carbon materials, leading to deterioration of their electrochemical performance; (4) Sulfur in carbon materials can have adverse effects on sodium-ion batteries, such as reducing battery cycle life and battery energy density. Therefore, obtaining sulfur-containing carbon anode materials based on medium-to-high-sulfur petroleum coke without desulfurization is a major technical challenge. Currently, there is no corresponding solution in the industry.

[0004] Chinese patent CN 202211181805.1 discloses a method for preparing graphite anode materials based on high-sulfur petroleum coke. The method involves mixing high-sulfur petroleum coke, a sulfur regulator, and a surface modifier, followed by granulation to obtain pellets. The pellets are then subjected to a first-stage calcination, a second-stage calcination under negative pressure, and finally graphitization calcination to obtain the graphite anode material. The high-sulfur petroleum coke contains a sulfur content greater than or equal to 3%. The sulfur regulator comprises component A and component B. Component A is (NH4+) 4+ ) n X, where X is an anion and n is the absolute value of the anion's valence; component B is MCl. m In this context, M represents a cation, and m represents the valence of the cation. This technology is a means to reduce the sulfur content in high-sulfur petroleum coke, but it does not make reasonable use of the advantage of sulfur in increasing the specific capacity of the negative electrode material. Furthermore, the desulfurization process of this technology generates a large amount of sulfur-containing tail gas, which requires desulfurization treatment before it can be emitted. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a sodium-ion battery carbon anode material based on high-sulfur petroleum coke, its preparation method, and its application. This invention utilizes low-cost, high-performance carbon anode materials prepared from medium-to-high-sulfur petroleum coke. This invention solves the problem of sulfur's deterioration of battery performance while retaining the sulfur element in the high-sulfur petroleum coke, thus avoiding the structural transformation of carbon materials caused by sulfur removal from high-sulfur petroleum coke, which leads to deterioration of the material's electrochemical performance.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing a sodium-ion battery carbon anode material based on high-sulfur petroleum coke, comprising the following steps: crushing high-sulfur petroleum coke raw material to the target particle size, then adding a sulfur-fixing agent, an inhibitor, and a surface modifier in an air atmosphere, followed by fusion granulation and gradient heating treatment, followed by depolymerization and demagnetization to obtain the carbon anode material.

[0007] Furthermore, the high-sulfur petroleum coke is a byproduct obtained from the residual oil during crude oil refining through a delayed coking process.

[0008] The target particle size of the high-sulfur petroleum coke feedstock after pulverization is D50 = 3-10 μm, preferably 3-5 μm;

[0009] The sulfur content in high-sulfur petroleum coke particles is greater than or equal to 2.4 wt%.

[0010] Furthermore, the sulfur-fixing agent comprises component A and component B, with the chemical formula A. m+x B n-ym is the valence of A, n is the valence of B, x is the absolute value of n, y is the absolute value of m, and x × m = y × n;

[0011] Component A is at least one of zinc, iron, and manganese; component B is NO3. - CH3COO - OH - HCO3 - O2 - At least one of them.

[0012] Under the aforementioned high-temperature calcination mechanism, the sulfur-fixing agent and high-sulfur petroleum coke of the AB combination exhibit the following effects: the high-temperature decomposition of component B can construct a macromolecular cross-linked structure and a porous structure, which, combined with the action of the inhibitor, inhibits the graphitization process of the high-sulfur petroleum coke and expands the d002 interlayer spacing of the carbon material; component A bonds with sulfur in the high-sulfur petroleum coke to achieve sulfur fixation, thereby improving the material's first-cycle coulombic efficiency, specific capacity, and long-cycle life; simultaneously, the surface modifier can coat the surface of the sulfur-fixed particles, forming a core-shell structure, further consolidating the sulfur fixation effect and improving the material's coulombic efficiency and cycle life.

[0013] Furthermore, the inhibitor is one or more of sodium phosphate, magnesium phosphate, and calcium phosphate.

[0014] Furthermore, the surface modifier is one or more of asphalt, phenolic resin, glucose, or sucrose.

[0015] Furthermore, the mass ratio of the high-sulfur petroleum coke, inhibitor, and surface modifier is 100:0.5-2:10-20;

[0016] The amount of sulfur-fixing agent added must satisfy Equation 1: Amount of sulfur-fixing agent added = [(mass of high-sulfur petroleum coke * sulfur content) / molecular molar mass of sulfur] * molecular molar mass of sulfur-fixing agent.

[0017] The mixing method for high-sulfur petroleum coke, desulfurizing agent, surface modifier, and inhibitor can be solid-phase mixing or solvent-assisted solid-phase mixing. For example, the desulfurizing agent is first dissolved in a solvent (the solvent can be a commonly used solvent that can dissolve the desulfurizing agent, such as deionized water, which is preferred), and then high-sulfur petroleum coke is added and dispersed (generally, a high-efficiency mixer can be used). Finally, it is mixed with the surface modifier and inhibitor and granulated (granulation can be carried out using a conventional fusion granulator). The preferred particle size is 12-20 μm.

[0018] Furthermore, the gradient heating treatment includes a first stage of calcination and a second stage of calcination;

[0019] The temperature T1 of the first calcination stage is 200-350℃, the heating rate is 1-5℃ / min, preferably 2℃ / min, and the calcination time is 2-4h; the first calcination is carried out under an inert atmosphere.

[0020] The second stage of calcination has a temperature T2 of 900-1300℃, a heating rate of 5-10℃ / min, preferably 5℃ / min, and a calcination time of 4-20h.

[0021] Furthermore, the inert atmosphere is one or a mixture of nitrogen, argon, and hydrogen; the inert gas pressure during the calcination process is 10-100 Pa.

[0022] The second objective of this invention is to provide a sodium-ion battery carbon anode material based on high-sulfur petroleum coke prepared by the method described above.

[0023] The third objective of this invention is to provide an application of a carbon anode material for sodium-ion batteries based on high-sulfur petroleum coke, using the carbon anode material as the anode material for sodium-ion secondary batteries.

[0024] Specifically, the carbon anode material is combined with a conductive agent and a binder to prepare a negative electrode slurry. The conductive agent and binder are both materials known in the industry. The obtained negative electrode slurry is loaded onto the surface of a conductive current collector to obtain a negative electrode sheet. Conventional methods, such as coating methods, can be used to coat the negative electrode material of this invention onto the conductive current collector to form the negative electrode sheet. The coating method and the conductive current collector are methods and materials known in the industry.

[0025] More preferably, the negative electrode sheet, positive electrode sheet, separator and electrolyte are assembled into a sodium-ion secondary battery.

[0026] The present invention also provides a sodium-ion secondary battery anode comprising the carbon anode material obtained by the preparation method described above.

[0027] The present invention also provides a sodium-ion secondary battery comprising the carbon anode material based on high-sulfur petroleum coke prepared by the aforementioned preparation method.

[0028] The sodium-ion secondary battery wherein the negative electrode sheet comprises the carbon negative electrode material.

[0029] Preferably, the sodium-ion secondary battery is a sodium-ion battery.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. This invention innovatively utilizes a desulfurizing agent to solve the problem of extremely poor electrochemical performance in high-sulfur petroleum coke-based carbon materials due to their high sulfur content. High-sulfur petroleum coke is calcined at high temperature with the assistance of a desulfurizing agent. Simultaneously, by jointly controlling the calcination temperature, calcination atmosphere, and particle size, a chemical transformation of sulfur in the high-sulfur petroleum coke can be achieved, accompanied by structural restructuring of the petroleum coke and the imparting of abundant porosity to the material, thus preventing the destructive effects of sulfur escape on the material structure. Research shows that the material prepared by this method possesses excellent specific capacity and long cycle life.

[0032] 2. The high-sulfur petroleum coke, sulfur-fixing agent, and inhibitor in this invention, through coordinated control of their proportions, high-temperature calcination mechanism, atmosphere, and temperature, are key to achieving the electrochemical performance of high-sulfur petroleum coke-based carbon anode materials, such as specific capacity and cycle life. Through the synergistic control of the raw materials and preparation process, the fixation of sulfur in the high-sulfur petroleum coke and the carbonization modification of the material can be coupled. Furthermore, by utilizing the gas-liquid-solid phase transformation process of the sulfur fixation process, the physical microstructure of the material can be improved, thereby enhancing the material's capacity, long cycle life, and other electrochemical performance.

[0033] 3. The carbon material prepared by this invention using petroleum coke as raw material, when used as a negative electrode material for sodium-ion batteries, achieves a reversible specific capacity of 298.6 mAh / g, a coulombic efficiency of 88.7% in the first cycle, and a capacity retention rate of 99.5% after 50 cycles. In contrast, conventional methods for preparing carbon anode materials for sodium-ion batteries result in a coulombic efficiency of <60% in the first cycle and a capacity retention rate of <50% after 50 cycles. Furthermore, this technical solution also features a short process, simple operation, low cost, and environmental friendliness. Attached Figure Description

[0034] Figure 1 Here is a SEM image of the high-sulfur petroleum coke feedstock from Example 1;

[0035] Figure 2 Here is a SEM image of the primary particles of high-sulfur petroleum coke after crushing in Example 1.

[0036] Figure 3 This is a SEM image of the carbon anode material obtained by fusion granulation in Example 1. Detailed Implementation

[0037] The following examples illustrate the specific steps of the present invention. It should be understood that these examples are merely illustrative and not intended to limit the scope of the invention in any way. Various processes and methods not described in detail in this invention are conventional methods known in the art.

[0038] All raw materials involved in this invention are commercially available products in the field. For example, the high-sulfur petroleum coke raw materials used in the following embodiments have an ash content of <1% and a total impurity content of <1000ppm for iron, cobalt, nickel, copper, and chromium.

[0039] Example 1

[0040] High-sulfur petroleum coke (sulfur content 3.2 wt%) (its SEM image is shown below) Figure 1 As shown in the image, primary particles with a diameter of 4 μm were crushed (SEM image shown). Figure 2 (As shown); 1000g of crushed high-sulfur petroleum coke primary particles, 10g of sodium phosphate, and 183.5g of anhydrous zinc acetate (based on chemical formula A) m+x B n-y Let m be the valence of A and n be the valence of B, and let x × m = y × n. In this embodiment, A is Zn and B is CH3COO. - 100g of asphalt (m=2, n=1, x=1, y=2) was mixed evenly in a high-efficiency mixer and then transferred to a granulation granulator for granulation to obtain secondary particles of 15μm. The obtained secondary particles were subjected to gradient heating heat treatment. First, the heating system was evacuated to a vacuum degree of 50Pa, then the temperature was increased to 300℃ (T1) at 2℃ / min and held for 3 hours. Then, the temperature was further increased to 1050℃ (T2) at 10℃ / min and held for 8 hours. After cooling, the resulting material was depolymerized and demagnetized to obtain the carbon anode material. The SEM image of this material is shown below. Figure 3 As shown in the figure, the material exhibits a near-spherical morphology, indicating that the fusion granulation has achieved the expected results. Figure 3 The illustration in the upper right corner shows a transmission scanning electron microscope, which clearly reveals an amorphous carbon structure on the material surface and a graphite-like crystalline phase structure inside. Depolymerization and demagnetization are routine operations in the field, and the equipment used is also common equipment in the field. For example, in this embodiment, depolymerization is performed by airflow crushing and classifying equipment (common equipment in the industry), resulting in a particle size D90 of less than 30 micrometers and a D50 of 6-8 micrometers.

[0041] The obtained carbon anode material was mixed with conductive agent Super P, dispersant NaCMC, binder SBR, and ultrapure water (18 MΩ / cm, 25℃) at a mass ratio of 8:1:0.4:0.6:15. The mixture was thoroughly stirred using a dual planetary mixer to obtain an anode slurry. This anode material was then coated onto a conductive current collector aluminum foil and dried to form the anode electrode sheet. The areal density of the electrode sheet was 6-10 mg / cm³. 2 ;

[0042] According to T / DCB 010—2024 "Technical Requirements for Hard Carbon Anode Materials for Sodium-ion Batteries", CR2032 coin cells were assembled in a dry glove box filled with argon gas, using the aforementioned carbon anode electrode as the working electrode, metallic sodium as the counter electrode, 1 mol / L NaPF6 EC / DEC (volume ratio 1:1) as the electrolyte, and glass fiber as the separator. Electrochemical performance tests were conducted at room temperature in the voltage range of 0.001-2.0V, and the charge / discharge test current density was 0.1C.

[0043] Example 2

[0044] Compared to Example 1, the only difference is that anhydrous zinc acetate is replaced with zinc hydroxide, and the amount added is calculated based on Equation 1. Other operations and parameters are the same as in Example 1.

[0045] Example 3

[0046] Compared to Example 1, the only difference is that anhydrous zinc acetate is replaced with zinc nitrate, the amount added is calculated based on Equation 1, and the temperature T1 is changed to 250°C. Other operations and parameters are the same as in Example 1.

[0047] Example 4

[0048] Compared to Example 1, the only difference is that anhydrous zinc acetate is replaced with ferric acetate, the amount added is calculated based on Equation 1, the temperature T1 is changed to 200°C, and the temperature T2 is changed to 950°C. Other operations and parameters are the same as in Example 1.

[0049] Example 5

[0050] Compared to Example 1, the only difference is that anhydrous zinc acetate is replaced with manganese acetate, the amount added is calculated based on Equation 1, the temperature T1 is changed to 350°C, and the temperature T2 is changed to 1100°C. Other operations and parameters are the same as in Example 1.

[0051] Example 6

[0052] Compared to Example 1, the only difference is that the asphalt is replaced with phenolic resin.

[0053] Compare with Example 1

[0054] Compared to Example 1, the difference is that no sulfur-fixing agent or inhibitor is used, and the steps are as follows:

[0055] High-sulfur petroleum coke (sulfur content 3.2 wt%) was crushed into primary particles with a particle size of 4 μm. 1000 g of the crushed primary particles of high-sulfur petroleum coke and 100 g of asphalt were mixed evenly in a high-efficiency mixer, and then transferred to a granulation granulator for granulation to obtain secondary particles of 15 μm. The obtained secondary particles were subjected to gradient heating heat treatment. First, the heating system was evacuated to a vacuum degree of 50 Pa, then the temperature was increased to 300℃ (T1) at 2℃ / min and held for 3 hours. Then, the temperature was further increased to 1050℃ (T2) at 10℃ / min and held for 8 hours. The resulting material after cooling is the carbon anode material.

[0056] The obtained carbon anode material was mixed with conductive agent Super P, dispersant NaCMC, binder SBR, and ultrapure water (18 MΩ / cm, 25℃) at a mass ratio of 8:1:0.4:0.6:15. The mixture was thoroughly stirred using a dual planetary mixer to obtain an anode slurry. This anode material was then coated onto a conductive current collector aluminum foil and dried to form the anode electrode sheet. The areal density of the electrode sheet was 6-10 mg / cm³. 2 ;

[0057] According to T / DCB 010—2024 "Technical Requirements for Hard Carbon Anode Materials for Sodium-ion Batteries", CR2032 coin cells were assembled in a dry glove box filled with argon gas, using the aforementioned carbon anode electrode as the working electrode, metallic sodium as the counter electrode, 1 mol / L NaPF6 EC / DEC (volume ratio 1:1) as the electrolyte, and glass fiber as the separator. Electrochemical performance tests were conducted at room temperature in the voltage range of 0.001-2.0V, and the charge / discharge test current density was 0.1C.

[0058] Comparative Example 2

[0059] Compared with Example 1, the difference is that the T1 insulation section is omitted, while other parameters and operating procedures are the same as in Example 1.

[0060] Comparative Example 3

[0061] Compared to Example 1, the only difference is that only an inhibitor is added, and no sulfur-fixing agent is added. Other parameters and operating procedures are the same as in Example 1.

[0062] Comparative Example 3

[0063] Compared to Example 1, the only difference is that only a sulfur-fixing agent is added, and no inhibitor is added. Other parameters and operating procedures are the same as in Example 1.

[0064] Comparative Example 4

[0065] Compared to Example 5, the difference is that no sulfur-fixing agent or inhibitor is used. Other parameters and operating procedures are the same as in Example 5.

[0066] Comparative Example 5

[0067] Compared to Example 6, the difference is that no sulfur-fixing agent or inhibitor is used. Other parameters and operating procedures are the same as in Example 6.

[0068] The product performance test results obtained from each embodiment and comparative example are shown in Table 1 below:

[0069] Table 1 Test results of the examples and comparative examples

[0070]

[0071]

[0072] As can be seen from the table above, the comparative example, without the introduction of a sulfur fixator and inhibitor, exhibited poor first-cycle coulombic efficiency and capacity retention during cycling. This is because, although sulfur is an electrochemically active element that can interact with sodium ions, its extremely poor reversibility leads to its poor electrochemical performance. In the example, by introducing a sulfur fixator and inhibitor, the interaction between transition metals and sulfur, combined with a rationally designed secondary particle structure, significantly improved the reversibility of sulfur, thereby achieving a substantial increase in both first-cycle coulombic efficiency and capacity retention during cycling.

[0073] This invention eliminates the need to remove sulfur from high-sulfur petroleum coke, thus the exhaust gas from high-temperature treatment does not require additional desulfurization equipment. Instead, it transforms the sulfur into metal sulfides or coordination compounds, which remain in the final product. Amorphous carbon materials are prepared at a temperature <1300℃, and the sodium-ion battery carbon anode materials prepared based on high-sulfur petroleum coke exhibit excellent performance.

[0074] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0075] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0076] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a sodium-ion battery carbon anode material based on high-sulfur petroleum coke, characterized in that, Includes the following steps: High-sulfur petroleum coke raw material is crushed to the target particle size, and then a sulfur-fixing agent, inhibitor, and surface modifier are added in an air atmosphere. After fusion granulation, the material is subjected to gradient heating treatment, followed by depolymerization and demagnetization to obtain the carbon anode material.

2. The method for preparing sodium-ion battery carbon anode material based on high-sulfur petroleum coke according to claim 1, characterized in that, The high-sulfur petroleum coke is a byproduct obtained from crude oil residue through a delayed coking process during crude oil refining. The target particle size of the high-sulfur petroleum coke feedstock after pulverization is D50 = 3-10 μm; The sulfur content in high-sulfur petroleum coke particles is greater than or equal to 2.4 wt%.

3. The method for preparing sodium-ion battery carbon anode material based on high-sulfur petroleum coke according to claim 1, characterized in that, The sulfur-fixing agent comprises component A and component B, with the chemical formula A. m+x B n-y m is the absolute value of the oxidation state of A, n is the absolute value of the oxidation state of B, and x×m=y×n; Component A is at least one of zinc, iron, and manganese; component B is NO3. - CH3COO - OH - HCO3 - O2 - At least one of them.

4. The method for preparing sodium-ion battery carbon anode material based on high-sulfur petroleum coke according to claim 1, characterized in that, The inhibitor is one or more of Na3PO4, Mg2(PO4)3, and Ca2(PO4)3.

5. The method for preparing sodium-ion battery carbon anode material based on high-sulfur petroleum coke according to claim 1, characterized in that, The surface modifier is asphalt, phenolic resin, glucose, or sucrose.

6. The method for preparing the sodium-ion battery carbon anode material based on high-sulfur petroleum coke according to claim 1, characterized in that, The mass ratio of the high-sulfur petroleum coke, inhibitor, and surface modifier is 100:0.5-2:10-20; The amount of sulfur-fixing agent added must satisfy Equation 1: Amount of sulfur-fixing agent added = [(mass of high-sulfur petroleum coke * sulfur content) / molecular molar mass of sulfur] * molecular molar mass of sulfur-fixing agent.

7. The method for preparing sodium-ion battery carbon anode material based on high-sulfur petroleum coke according to claim 1, characterized in that, The gradient heating treatment includes a first stage of calcination and a second stage of calcination; The first calcination stage has a temperature T1 of 200–350℃, a heating rate of 1–5℃ / min, and a calcination time of 2–4 h; the first calcination is carried out under an inert atmosphere. The second stage of calcination has a temperature T2 of 900-1300℃, a heating rate of 5-10℃ / min, and a calcination time of 4-20h.

8. The method for preparing sodium-ion battery carbon anode material based on high-sulfur petroleum coke according to claim 7, characterized in that, The inert atmosphere is one or a mixture of nitrogen, argon, and hydrogen; the inert gas pressure during the calcination process is 10-100 Pa.

9. A sodium-ion battery carbon anode material based on high-sulfur petroleum coke, prepared by the method described in any one of claims 1-8.

10. An application of the sodium-ion battery carbon anode material based on high-sulfur petroleum coke as described in claim 9, characterized in that, The carbon anode material is used as the anode material for sodium-ion secondary batteries.

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