Preparation method and application of multi-component non-metal element modified anthracite-based carbon negative electrode material

Abstract

The application discloses a preparation method and application of a multi-component non-metal element modified anthracite-based carbon negative electrode material, and belongs to the technical field of sodium ion battery negative electrode materials. After being ball milled and screened and impurity-removed by acid pickling, anthracite is pre-oxidized, mixed with ammonium chloride, ball milled, and then subjected to low-temperature (less than or equal to 500 DEG C) heat treatment in an inert atmosphere to obtain a nitrogen-chlorine-oxygen co-doped anthracite material, and finally subjected to secondary low-temperature heat treatment in an inert atmosphere containing a sulfur (or selenium) source to obtain a nitrogen-chlorine-oxygen-sulfur (selenium) doped anthracite-based carbon negative electrode material. The application effectively improves the discharge specific capacity and rate performance of the coal-based carbon material by combining the regulation of various non-metal elements with low-temperature heat treatment. The preparation method is simple and controllable, the raw materials are widely available and low in cost, and the method is suitable for batch production and has a good development prospect in the field of electrode material preparation or energy storage application (such as sodium ion batteries).

Description

Technical Field

[0001] This invention belongs to the technical field of sodium-ion battery anode materials, and particularly relates to a method for preparing and applying anthracite-based carbon anode material modified with multi-component non-metallic elements. Background Technology

[0002] With the rapid development of the new energy industry, the scale of grid connection for renewable energy sources such as wind and solar power is constantly expanding, leading to a growing demand for efficient and low-cost energy storage technologies. While lithium-ion batteries possess high energy density and a mature industrial foundation, their application in large-scale energy storage is limited by the finite and uneven distribution of lithium resources and their high cost. In contrast, sodium resources are abundant, widely available, and inexpensive, while sodium-ion batteries offer advantages in safety and environmental adaptability. Therefore, sodium-ion batteries are considered an important complement to lithium-ion batteries, showing promising application prospects in large-scale and low-cost energy storage.

[0003] Among various sodium-ion battery anode materials, carbon materials are considered to have the greatest application potential due to their good conductivity, structural stability, low cost, and wide availability. Anthracite, with its abundant reserves, low price, high fixed carbon content, and well-developed aromatic layered structure, is an excellent coal-based carbon precursor. Compared to graphite, sodium ions have a larger radius, making effective intercalation difficult. Anthracite-based carbon, after regulation, is more likely to form suitable interlayer structures and defect sites, which is beneficial for sodium storage. Compared to biomass carbon, its stable source and uniform composition make it more suitable for large-scale applications. Furthermore, its cost is lower than some artificially synthesized carbon materials, giving it good industrialization prospects. However, traditional anthracite-based carbon materials still suffer from problems such as low specific capacity and insufficient rate performance, requiring further optimization.

[0004] The preparation of high-temperature hard carbon often requires higher heat treatment temperatures and more complex processes, resulting in higher overall manufacturing costs. Therefore, from the perspectives of economy and raw material utilization, the low-temperature route using anthracite is more advantageous. Thus, developing a low-temperature heteroatom-doped coal-based material has significant research and application value. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a method for preparing and applying anthracite-based carbon anode materials modified with multi-component non-metallic elements. The method of this invention optimizes the preparation process of anthracite-based carbon anode materials, regulates the synergistic doping of non-metallic elements, and improves sodium storage performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing anthracite-based carbon anode material modified with multiple non-metallic elements, comprising the following steps: Anthracite is ball-milled, sieved, and acid-washed in sequence to obtain purified anthracite. The purified anthracite is then pre-oxidized in air to obtain pre-oxidized anthracite. The pre-oxidized anthracite was mixed with ammonium chloride and then ball-milled, and then subjected to low-temperature heat treatment under an inert atmosphere to obtain nitrogen, chlorine and oxygen co-doped anthracite, wherein the temperature of the low-temperature heat treatment was ≤500 ℃. One of the sulfur source and the selenium source is mixed with the nitrogen, chlorine and oxygen co-doped anthracite and subjected to a second low-temperature heat treatment to obtain a multi-component non-metallic element modified anthracite-based carbon anode material, wherein the temperature of the second low-temperature heat treatment is ≤500℃.

[0007] This invention proposes a method for preparing anthracite-based carbon anode materials modified with multiple non-metallic elements. After simple pretreatment, acid washing, and pre-oxidation, nitrogen-chlorine co-doping is used to regulate the defect structure and microcrystalline order of the carbon material. Further, sulfur (selenium) doping introduces more electrochemical active sites and optimizes the surface electronic structure. This synergistic regulation strategy effectively improves the carbon layer structure and increases the number of active sites, promoting the sodium ion insertion / extraction process, thereby significantly improving the material's sodium storage capacity, rate performance, and cycle stability.

[0008] This invention effectively modulates the electronic structure of carbon materials by introducing heteroatoms such as N, Cl, O, S, and Se for doping, increasing defects and active sites, and improving ion transport kinetics, thereby significantly enhancing their sodium storage performance. Unlike existing sodium electrode anode material preparation techniques, which require complex steps such as the use of pore-forming agents and high-temperature calcination, this invention employs low-temperature sintering throughout the process. Through the diffusion of non-metallic elements and their combination with the carbon matrix, a high concentration of defect sites is formed. Under the combined action of multiple non-metallic elements, high sodium storage performance is achieved. Furthermore, in terms of yield and cost, low-temperature carbonization makes it easier to obtain higher yields; the carbon materials prepared using this method have a finished product yield greater than 85%. Moreover, low-temperature sintering results in lower energy consumption and equipment requirements.

[0009] Furthermore, in the anthracite-based carbon anode material modified with multi-component non-metallic elements, the total content of non-metallic elements (i.e., N, Cl, O, S or N, Cl, O, Se) is 4~20 wt%.

[0010] Furthermore, during the pickling process, the acid used is a mixed solution of hydrochloric acid and hydrofluoric acid, the pickling temperature is 140~180 ℃, the pickling time is 12~20 h, and the molar ratio of hydrochloric acid to hydrofluoric acid is (10~50):1.

[0011] Furthermore, the hydrothermal treatment is performed at a temperature of 140~180 ℃ for a time of 12~20 h.

[0012] Further, the pre-oxidation treatment step is as follows: the purified anthracite is heated to 350-450 ℃ at a heating rate of 5-10 ℃ / min, kept at this temperature for 2-4 h, and then naturally cooled to room temperature.

[0013] Furthermore, when ball milling pre-oxidized anthracite and ammonium chloride, the milling beads are zirconia balls, the rotation speed is 800 r / min, and the milling time is 4 h.

[0014] Furthermore, the mass ratio of the pre-oxidized anthracite to ammonium chloride is (1~4):1; The heating rate of the low-temperature heat treatment is 5~10 ℃ / min, and the holding time is 2~4 h.

[0015] Furthermore, the mass ratio of the nitrogen-chlorine-oxygen co-doped anthracite to the sulfur source or selenium source is 1:(5~10). The holding time for the secondary low-temperature heat treatment is 2-4 hours.

[0016] The present invention also provides a multi-component non-metallic element modified anthracite-based carbon anode material prepared according to the above preparation method, which is a nitrogen, chlorine, oxygen, and sulfur-doped anthracite material or a nitrogen, chlorine, oxygen, and selenium-doped anthracite material.

[0017] The present invention also provides an application of the above-mentioned multi-component non-metallic element modified anthracite-based carbon anode material in sodium-ion batteries.

[0018] The present invention also provides a sodium-ion battery, wherein the negative electrode material is the above-mentioned anthracite-based carbon negative electrode material modified with multi-component non-metallic elements.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects: This invention modifies anthracite coal through ball milling, acid washing, pre-oxidation, low-temperature heat treatment, and secondary low-temperature heat treatment to achieve nitrogen, chlorine, oxygen, and sulfur (selenium) co-doping. The resulting sample, compared to unmodified samples and commercial hard carbon, maintains a high reversible capacity under long-cycle and high-rate charge-discharge conditions. Furthermore, this invention offers significant application advantages: the overall process is simple and straightforward, easy to operate, and readily scalable; high-performance carbon anodes can be prepared at low temperatures (≤500 °C), effectively reducing energy consumption. Simultaneously, the invention boasts a high carbon yield, significantly improving the formation efficiency of the target product and enhancing economic value; the relevant process parameters are flexible and highly controllable, allowing for precise adjustment according to actual needs, and possess excellent industrial application prospects. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 SEM images of anthracite-based carbon anode materials from Examples 1, 5, 1, 2, 3, and 6. Figure 2 The XRD patterns of the anthracite-based carbon anode materials modified with multi-component non-metallic elements in Examples 1 and 5, and the anthracite-based carbon anode materials in Comparative Examples 3 and 6 are shown. Figure 3 The first charge-discharge curves of sodium-ion batteries prepared using the anthracite-based carbon anode materials modified with multi-component non-metallic elements in Examples 1 and 5 and the anthracite-based carbon anode materials in Comparative Examples 3 and 6 are shown. Figure 4 The charge-discharge curves of sodium-ion batteries prepared using the anthracite-based carbon anode materials modified with multi-component non-metallic elements in Examples 1 and 5, and the carbon anode materials in Comparative Examples 3, 6, and 7, are shown at a current density of 1 A / g. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0026] Embodiments of the present invention provide a method for preparing anthracite-based carbon anode material modified with multiple non-metallic elements, comprising the following steps: Anthracite is ball-milled, sieved, and acid-washed (for purification) to obtain purified anthracite. The purified anthracite is then pre-oxidized in air to obtain pre-oxidized anthracite. Pre-oxidized anthracite was mixed with ammonium chloride and then ball-milled, followed by low-temperature heat treatment under an inert atmosphere to obtain nitrogen, chlorine and oxygen co-doped anthracite. The temperature of the low-temperature heat treatment was ≤500 ℃. One of the sulfur source and selenium source is mixed with nitrogen, chlorine and oxygen co-doped anthracite and subjected to a second low-temperature heat treatment to obtain anthracite-based carbon anode material modified with multiple non-metallic elements. The temperature of the second low-temperature heat treatment is ≤500 ℃. Through the second heat treatment, the introduction of sulfur (selenium) elements and the optimization of the microstructure of carbon materials can be further realized.

[0027] This invention involves ball milling and sieving anthracite, followed by acid washing to remove impurities, and then pre-oxidation. The mixture is then mixed with ammonium chloride and ball milled again. Following this, it undergoes low-temperature heat treatment (≤500 °C) in an inert atmosphere to obtain nitrogen-chlorine-oxygen co-doped anthracite material. Finally, a second low-temperature heat treatment is performed in an inert atmosphere containing a sulfur (or selenium) source to obtain nitrogen-chlorine-oxygen-sulfur (selenium) doped anthracite-based carbon anode material. This invention effectively improves the discharge specific capacity and rate performance of coal-based carbon materials by combining the regulation of various non-metallic elements with low-temperature heat treatment. The preparation method is simple, highly controllable, and uses widely available and low-cost raw materials, making it suitable for mass production. It has good development prospects in electrode material preparation or energy storage applications (such as sodium-ion batteries).

[0028] In a preferred embodiment of the present invention, anthracite is ball-milled and sieved to obtain uniform particles with a D50 size of 5 μm.

[0029] In a preferred embodiment of the present invention, the total content of non-metallic elements in the anthracite-based carbon anode material modified with multiple non-metallic elements is 5-20 wt%.

[0030] In a preferred embodiment of the present invention, pickling is performed using a mixed solution of hydrochloric acid and hydrofluoric acid under hydrothermal conditions. The pickling temperature is 140~180 ℃ and the time is 12~20 h.

[0031] In a preferred embodiment of the present invention, the molar ratio of hydrochloric acid to hydrofluoric acid is (10~50):1.

[0032] In a preferred embodiment of the present invention, the pre-oxidation treatment step is as follows: the purified anthracite is heated to 350-450 ℃ at a heating rate of 5-10 ℃ / min, kept at this temperature for 2-4 h, and then naturally cooled to room temperature. The purpose of this step is to remove impurities and introduce oxygen-containing functional groups.

[0033] In a preferred embodiment of the present invention, when ball milling pre-oxidized anthracite and ammonium chloride, the milling beads are zirconia balls, the rotation speed is 800 r / min, and the milling time is 4 h.

[0034] In a preferred embodiment of the present invention, the mass ratio of pre-oxidized anthracite to ammonium chloride is (1~4):1; The heating rate for low-temperature heat treatment is 5~10 ℃ / min, the temperature is 300~500℃, and the holding time is 2~4 h.

[0035] In a preferred embodiment of the present invention, the mass ratio of nitrogen-chlorine-oxygen co-doped anthracite to sulfur source or selenium source is 1:(5~10). The temperature for the secondary low-temperature heat treatment is 300~500℃, and the holding time is 2~4 h.

[0036] For example, the sulfur source is thiourea, and the selenium source is selenium powder.

[0037] An embodiment of the present invention also provides a multi-component non-metallic element modified anthracite-based carbon anode material prepared according to the above preparation method, which is a nitrogen, chlorine, oxygen, and sulfur-doped anthracite material or a nitrogen, chlorine, oxygen, and selenium-doped anthracite material.

[0038] Embodiments of the present invention also provide an application of the above-mentioned multi-component non-metallic element modified anthracite-based carbon anode material in sodium-ion batteries.

[0039] An embodiment of the present invention also provides a sodium-ion battery, wherein the negative electrode material is the above-mentioned anthracite-based carbon negative electrode material modified with multi-component non-metallic elements.

[0040] In a preferred embodiment of the present invention, the steps for preparing a sodium-ion battery using the anthracite-based carbon anode material modified with multi-component non-metallic elements according to the present invention are as follows: A multi-component non-metallic element-modified anthracite-based carbon anode material and PVDF (polyvinylidene fluoride) were mixed at a mass ratio of 85:15, and degassed to obtain a slurry. The slurry was then coated onto an aluminum foil, with the loading of the multi-component non-metallic element-modified anthracite-based carbon anode material ranging from 1.0 to 1.5 mg / cm³. 2 The electrodes were dried to obtain electrode sheets. The electrode sheets were then assembled into a sodium-ion battery in a glove box. A glass fiber separator was used as the separator, and a commercial sodium hexafluorophosphate electrolyte was used as the electrolyte. After assembly, the battery was allowed to stand for 12 hours before electrochemical testing was performed.

[0041] For example, the sodium hexafluorophosphate electrolyte is 1 M NaPF6, the organic solution is composed of EC (ethylene carbonate):DEC (diethyl carbonate) = 1:1 (volume ratio), and 5.0% (volume fraction) of FEC (fluoroethylene carbonate) is added.

[0042] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0043] All raw materials used in the embodiments of this invention were purchased commercially. In the following embodiments, the glass fiber diaphragm was purchased from Whatman, model GF / D-1823-090; the aluminum foil was purchased from Kejing Zhida Technology Co., Ltd., with a thickness of 16 mm.

[0044] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0045] The technical solution of the present invention will be further illustrated by the following embodiments.

[0046] Example 1 A method for preparing a multi-component non-metallic element-modified anthracite-based carbon anode material, comprising the following steps: S1. Grind anthracite briquettes and sieve them to obtain D. 50 The sample obtained from uniform particles with a size of 5 μm is denoted as C; S2. Add 5g of sample C to a mixed solution of 50 mL of 5 M hydrochloric acid and 1 mL of 40 wt% hydrofluoric acid (in this example, the molar ratio of hydrochloric acid to hydrofluoric acid is 11:1), and react at 160 °C for 15 h under hydrothermal conditions to remove mineral impurities and obtain purified anthracite, denoted as AC. S3. Heat AC to 400 ℃ in a muffle furnace at 5 ℃ / min and hold for 4 h. Then cool naturally to room temperature to obtain pre-oxidized anthracite, denoted as HC. S4. HC and ammonium chloride are ball-milled at a mass ratio of 2:1, with zirconia balls as the milling beads, at a speed of 800 r / min for 4 h. Then, the mixture is heated to 400 ℃ at a nitrogen atmosphere at a rate of 5 ℃ / min and held for 4 h to obtain nitrogen-chlorine-oxygen co-doped anthracite, denoted as HN-C. S5. HN-C and thiourea are placed in a tube furnace at a mass ratio of 1:10 for secondary low-temperature heat treatment, with thiourea located at the upper vent and HN-C at the lower vent. The reaction is carried out at 400 °C for 4 h under a nitrogen atmosphere to obtain a multi-component non-metallic element modified anthracite-based carbon anode material, which is a nitrogen, chlorine, oxygen, and sulfur co-doped anthracite material, denoted as HN-C+S. In this embodiment, the total content of non-metallic elements (i.e., nitrogen, chlorine, oxygen, and sulfur) is 16.5 wt%; the yield of the anthracite anode material is 87.3%.

[0047] Example 2 A method for preparing a multi-component non-metallic element modified anthracite-based carbon anode material is the same as in Example 1, except that the mass ratio of HN-C to thiourea in S5 is 1:5.

[0048] In the anthracite-based carbon anode material modified with multiple non-metallic elements in this embodiment, the total content of non-metallic elements is 18.1 wt%; the yield of the anode material generated from anthracite is 85.9%.

[0049] Example 3 A method for preparing a multi-component non-metallic element modified anthracite-based carbon anode material is the same as in Example 1, except that the secondary low-temperature heat treatment temperature in S5 is 300 °C.

[0050] Example 4 A method for preparing a multi-component non-metallic element-modified anthracite-based carbon anode material, comprising the following steps: S1, Same as Example 1; S2. Add 5g of sample C to a mixed solution of 50 mL of 5 M hydrochloric acid and 1 mL of 40 wt% hydrofluoric acid (in this example, the molar ratio of hydrochloric acid to hydrofluoric acid is 11:1), and react at 180 ℃ hydrothermal conditions for 12 h to remove mineral impurities, and obtain purified anthracite, denoted as AC. S3. Heat AC to 350 ℃ in a muffle furnace at 5 ℃ / min and hold for 4 h. Then cool naturally to room temperature to obtain pre-oxidized anthracite, denoted as HC. S4. HC and ammonium chloride are ball-milled at a mass ratio of 2:1 and heat-treated at 300 °C for 4 h under a nitrogen atmosphere to obtain nitrogen-chlorine-oxygen co-doped anthracite, denoted as HN-C. S5. Take HN-C and thiourea at a mass ratio of 1:10 and put them into a tube furnace for secondary low-temperature heat treatment, wherein thiourea is located at the upper vent and HN-C is located at the lower vent. React at 500 °C for 3 h under a nitrogen atmosphere to obtain a multi-component non-metallic element modified anthracite-based carbon anode material, denoted as HN-C+S.

[0051] Example 5 A method for preparing a multi-component non-metallic element modified anthracite-based carbon anode material is the same as in Example 2, except that thiourea is replaced with an equal mass of selenium powder to ensure that the mass ratio of HN-C to selenium powder is 1:5.

[0052] The anthracite-based carbon anode material modified by non-metallic elements obtained in this embodiment is a nitrogen, chlorine, oxygen, and selenium co-doped anthracite material. In the anthracite-based carbon anode material modified by non-metallic elements in this embodiment, the total content of non-metallic elements (i.e., nitrogen, chlorine, oxygen, and selenium) is 12.3 wt%; the yield of the anthracite anode material is 88.5%.

[0053] Example 6 A method for preparing a multi-component non-metallic element modified anthracite-based carbon anode material is the same as in Example 5, except that the secondary low-temperature heat treatment time in S5 is 2 h.

[0054] Comparative Example 1 A method for preparing anthracite-based carbon anode material: The steps are as follows: Anthracite briquettes are milled and sieved to obtain D. 50 The sample obtained from uniform particles with a size of 5 μm is denoted as C.

[0055] Comparative Example 2 A method for preparing anthracite-based carbon anode material, comprising the following steps: S1, Same as Example 1; S2. Add 5g of sample C to a mixed solution of 50 mL of 5 M hydrochloric acid and 1 mL of 40 wt% hydrofluoric acid, and react at 160℃ for 15 h to remove mineral impurities, and obtain purified anthracite, denoted as AC.

[0056] Comparative Example 3 A method for preparing anthracite-based carbon anode material, comprising the following steps: S1, Same as Example 1; S2. Add 5g of sample C to a mixed solution of 50 mL of 5 M hydrochloric acid and 1 mL of 40 wt% hydrofluoric acid, and react at 160℃ for 15 h to remove mineral impurities, and obtain purified anthracite, denoted as AC. S3. Heat AC to 400 ℃ in a muffle furnace at 5 ℃ / min and hold for 4 h. Then cool naturally to room temperature to obtain pre-oxidized anthracite, denoted as HC.

[0057] Comparative Example 4 A method for preparing anthracite-based carbon anode material, comprising the following steps: S1, Same as Example 1; S2. Add 5g of sample C to a mixed solution of 50 mL of 5 M hydrochloric acid and 1 mL of 40 wt% hydrofluoric acid, and react at 160℃ for 15 h to remove mineral impurities, and obtain purified anthracite, denoted as AC. S3. Heat AC to 400 ℃ in a muffle furnace at 5 ℃ / min and hold for 4 h. Then cool naturally to room temperature to obtain pre-oxidized anthracite, denoted as HC. S4. HC and urea are ball-milled at a mass ratio of 2:1 and then heat-treated at 400 °C for 4 h under a nitrogen atmosphere to obtain a nitrogen-oxygen-doped sample, denoted as NC.

[0058] Comparative Example 5 A method for preparing anthracite-based carbon anode material, comprising the following steps: S1, Same as Example 1; S2. Add 5g of sample C to a mixed solution of 50 mL of 5 M hydrochloric acid and 1 mL of 40 wt% hydrofluoric acid, and react at 160℃ for 15 h to remove mineral impurities, and obtain purified anthracite, denoted as AC. S3. Heat AC to 400 ℃ in a muffle furnace at 5 ℃ / min and hold for 4 h. Then cool naturally to room temperature to obtain pre-oxidized anthracite, denoted as HC. S4. HC and sodium chloride were ball-milled at a mass ratio of 2:1 and then heat-treated at 400 °C for 4 h under a nitrogen atmosphere to obtain a chlorine-oxygen doped sample, denoted as Cl-C.

[0059] Comparative Example 6 A method for preparing anthracite-based carbon anode material, comprising the following steps: S1, Same as Example 1; S2. Add 5g of sample C to a mixed solution of 50 mL of 5 M hydrochloric acid and 1 mL of 40 wt% hydrofluoric acid, and react at 160℃ for 15 h to remove mineral impurities, and obtain purified anthracite, denoted as AC. S3. Heat AC to 400 ℃ in a muffle furnace at 5 ℃ / min and hold for 4 h. Then cool naturally to room temperature to obtain pre-oxidized anthracite, denoted as HC. S4. HC and ammonium chloride are ball-milled at a mass ratio of 2:1 and heat-treated at 400 °C for 4 h under a nitrogen atmosphere to obtain nitrogen-chlorine-oxygen co-doped anthracite, denoted as HN-C.

[0060] Comparative Example 7 Commercial hard carbon Kuraray.

[0061] Figure 1 The SEM images of the anthracite-based carbon anode materials from Examples 1 and 5, and Comparative Examples 1, 2, 3, and 6 show that Comparative Example 1 exhibits a dense blocky / sheet-like agglomerate structure with a relatively smooth surface. Comparative Example 2, after acid washing and impurity removal, shows clearer sheet outlines after the removal of mineral impurities. The surface of Comparative Example 3, after pre-oxidation, changes from smooth to wrinkled and undulating, with thinner sheets and significantly increased roughness. Comparative Example 6, after nitrogen and chlorine co-doping, shows further sheet peeling and curling, resulting in a looser stack. The materials from Examples 1 and 5, after further secondary sulfidation (selenization), show more significant refinement, with an increase in fine particles on the surface and further increases in edge structures and defect sites.

[0062] Figure 2 The XRD patterns of the anthracite-based carbon anode materials modified with multi-component non-metallic elements in Examples 1 and 5, and the anthracite-based carbon anode materials in Comparative Examples 3 and 6, show that the anthracite-based carbon anode materials in Comparative Examples 3 and 6 maintain a typical disordered amorphous carbon structure. In contrast, the (002) peak of the anthracite-based carbon anode materials modified with multi-component non-metallic elements in Examples 1 and 5 is significantly shifted to a lower angle and broadened, confirming that the introduction of large atomic radius sulfur (selenium) effectively widens the interlayer spacing and increases structural defects. This synergistic effect of interlayer spacing expansion and defect construction optimizes sodium ion migration kinetics while also increasing chemisorption sites.

[0063] The electrode materials of Examples 1-6 and Comparative Examples 1-7 were used to prepare sodium-ion batteries, and the steps are as follows: Electrode material and PVDF (polyvinylidene fluoride) were mixed at a mass ratio of 85:15, and degassed to obtain a slurry. The slurry was then coated onto an aluminum foil substrate, with the electrode material loading being 1.2 mg / cm². 2 The electrodes were then dried to obtain electrode sheets. These electrode sheets were then assembled into a sodium-ion battery in a glove box. A glass fiber separator was used as the separator, and 1 M NaPF6 was used as the electrolyte. The organic solution consisted of EC:DEC = 1:1 (volume ratio), with 5.0% FEC added. After assembly, the battery was allowed to stand for 12 h. The battery was first activated using cyclic voltammetry, followed by electrochemical tests at current densities of 50 mA / g and 1 A / g, respectively. No standing time was required after each cycle. The results are shown in Table 1.

[0064] Table 1 From the electrochemical data in Table 1, it can be seen that nitrogen and chlorine doping effectively improves the structural stability of anthracite-based carbon anode materials (combined with...). Figure 2 The material exhibits improved charge transport properties, thereby enhancing cycle stability. Furthermore, the introduction of sulfur (selenium) significantly increases the specific capacity of the material. This is mainly attributed to the fact that sulfur (selenium) doping can effectively regulate the microstructure and surface chemical properties of anthracite, increase defect sites and interlayer spacing, improve the material's conductivity and ion diffusion kinetics, and provide more reversible energy storage active sites, thereby enhancing electrochemical reaction activity and improving reversible energy storage capacity and discharge specific capacity.

[0065] Figure 3 The first charge-discharge curves of sodium-ion batteries prepared using the anthracite-based carbon anode materials modified with multi-component non-metallic elements in Examples 1 and 5, and the anthracite-based carbon anode materials in Comparative Examples 3 and 6, are shown. It can be observed that the discharge specific capacity of the sodium-ion batteries prepared using the anthracite-based carbon anode materials modified with multi-component non-metallic elements in Examples 1 and 5 is significantly higher than that of Comparative Examples 3 and 6, indicating that the sodium storage capacity of the nitrogen, chlorine, sulfur, and oxygen (selenium) doped samples is significantly enhanced. At the same time, the slope characteristics of the curves are more obvious, indicating that the sodium storage process is more due to the synergistic effect of defect adsorption, surface pseudocapacitance, and interlayer embedding.

[0066] Figure 4 The figures show the charge-discharge curves of sodium-ion batteries prepared using the anthracite-based carbon anode materials modified with multi-component non-metallic elements in Examples 1 and 5, and the carbon anode materials in Comparative Examples 3, 6, and 7, at a current density of 1 A / g. It can be seen that even at high currents, the electrode materials still maintain a high specific capacity, indicating that nitrogen, chlorine, sulfur, and oxygen (selenium) co-doping introduces more active sites, enhances the conductivity of the electrode materials, promotes the insertion and extraction of sodium ions, and thus improves the battery capacity.

[0067] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a multi-component non-metallic element-modified anthracite-based carbon anode material, characterized in that, Includes the following steps: Anthracite is ball-milled, sieved, and acid-washed in sequence to obtain purified anthracite. The purified anthracite is then pre-oxidized in air to obtain pre-oxidized anthracite. The pre-oxidized anthracite was mixed with ammonium chloride and then ball-milled, and then subjected to low-temperature heat treatment under an inert atmosphere to obtain nitrogen, chlorine and oxygen co-doped anthracite. The temperature of the low-temperature heat treatment was ≤500 ℃. One of the sulfur source and the selenium source is mixed with the nitrogen-chlorine co-doped anthracite and subjected to a second low-temperature heat treatment to obtain a multi-component non-metallic element modified anthracite-based carbon anode material, wherein the temperature of the second low-temperature heat treatment is ≤500 ℃.

2. The method for preparing the multi-component non-metallic element-modified anthracite-based carbon anode material according to claim 1, characterized in that, In the anthracite-based carbon anode material modified with multi-component non-metallic elements, the total content of non-metallic elements is 5~20wt%.

3. The method for preparing the multi-component non-metallic element-modified anthracite-based carbon anode material according to claim 1, characterized in that, The acid used in the pickling process is a mixed solution of hydrochloric acid and hydrofluoric acid, the pickling temperature is 140~180℃, and the pickling time is 12~20 h.

4. The method for preparing the multi-component non-metallic element-modified anthracite-based carbon anode material according to claim 3, characterized in that, The molar ratio of hydrochloric acid to hydrofluoric acid is (10~50):

1.

5. The method for preparing the multi-component non-metallic element-modified anthracite-based carbon anode material according to claim 1, characterized in that, The pre-oxidation treatment step is as follows: the purified anthracite is heated to 350-450 ℃ at a heating rate of 5-10 ℃ / min, kept at this temperature for 2-4 h, and then naturally cooled to room temperature.

6. The method for preparing the multi-component non-metallic element-modified anthracite-based carbon anode material according to claim 1, characterized in that, The mass ratio of the pre-oxidized anthracite to ammonium chloride is (1~4):1; The heating rate of the low-temperature heat treatment is 5~10 ℃ / min, the temperature is 300~500℃, and the holding time is 2~4 h.

7. The method for preparing the multi-component non-metallic element-modified anthracite-based carbon anode material according to claim 1, characterized in that, The mass ratio of the nitrogen-chlorine co-doped anthracite to the sulfur source or selenium source is 1:(5~10). The secondary low-temperature heat treatment is performed at a temperature of 300~500℃ for 2~4 hours.

8. A multi-component non-metallic element-modified anthracite-based carbon anode material, characterized in that, The material prepared by the preparation method according to any one of claims 1 to 7 is a nitrogen, chlorine, oxygen, and sulfur-doped anthracite material or a nitrogen, chlorine, oxygen, and selenium-doped anthracite material.

9. The application of a multi-component non-metallic element modified anthracite-based carbon anode material as described in claim 8 in sodium-ion batteries.

10. A sodium-ion battery, characterized in that, The anode material is the anthracite-based carbon anode material modified with multi-component non-metallic elements as described in claim 8.

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