A method for preparing high-capacity high-rate resin-based hard carbon based on a template method, and applications

Abstract

The application belongs to the technical field of carbon materials, and particularly relates to a method for preparing high-capacity high-rate resin-based hard carbon based on a template method and application. Thermoplastic resin is dissolved, then an additive is added, and uniform stirring is performed, then drying is performed, and irradiation is performed under a UV lamp to obtain crosslinked and cured resin; the crosslinked and cured resin is pre-carbonized to obtain pre-carbonized material; the pre-carbonized material is crushed to obtain crushed material; the crushed material is subjected to immersion treatment and drying to obtain dried material; the dried material and a coating agent are mixed to obtain mixed material; and the mixed material is carbonized to obtain high-capacity high-rate resin-based hard carbon. The application constructs a hierarchical structure rich in defects and nanochannels in the hard carbon, and improves the sodium storage capacity, rate performance and cycle stability of a sodium ion battery.

Description

Technical Field

[0001] This invention belongs to the field of carbon materials technology, specifically relating to a method and application for preparing high-capacity, high-rate resin-based hard carbon based on a template method. Background Technology

[0002] Hard carbon materials, as the most widely used anode materials in the commercialization of SIBs, possess many advantages, such as a wide range of precursor choices and low cost. However, they still face several pressing challenges, including low initial coulombic efficiency (ICE), poor long-term cycling stability, insufficient rate performance, and limited sodium ion storage capacity. Specifically, the large specific surface area of ​​hard carbon easily leads to excessive formation of the solid electrolyte interface (SEI), resulting in irreversible sodium loss and consequently reducing ICE. Furthermore, the structural instability of hard carbon affects its rate performance and cycling performance. Phenolic resins, as one of the precursors for hard carbon, exhibit significant advantages, including high carbon yield, easily adjustable molecular structure, simple synthesis process, and widely available and highly consistent raw materials. These characteristics greatly stimulate our research interest in the relationship between the microstructure of hard carbon and the precursor structure. Secondly, from a commercial perspective, phenolic resins have significant advantages due to their cost-effectiveness, mature industrial production capabilities, and stable supply chain. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method and application for preparing high-capacity, high-rate resin-based hard carbon based on template method, thereby solving the problems mentioned in the background art.

[0004] The technical solution adopted in this invention is as follows: In a first aspect, a method for preparing high-capacity, high-rate resin-based hard carbon based on a template method includes the following steps: Thermoplastic resin is dissolved, then additives are added and stirred thoroughly. The mixture is then dried and irradiated under a UV lamp to obtain cross-linked and cured resin. The cross-linked and cured resin is pre-carbonized to obtain pre-carbonized material. The pre-carbonized material is pulverized to obtain pulverized material. The pulverized material is impregnated and dried to obtain dried material. The dried material and coating agent are mixed to obtain a mixture. The mixture is carbonized to obtain high-capacity, high-ratio resin-based hard carbon.

[0005] Furthermore, thermoplastic resins include phenolic resins.

[0006] Furthermore, the additives include ZnCl2 and / or FeCl3.

[0007] It should be noted that adding additives during the crosslinking stage can generate uniformly distributed templates in situ within the resin skeleton; after pre-carbonization, these template locations form primary channels; during impregnation treatment, due to the presence of primary channels, the impregnation solution (nitric acid solution) can penetrate deeper into the material interior, rather than just oxidizing the surface; the gas generated by the decomposition of nitric acid creates secondary pores within the confined primary channels, forming a hierarchical structure of micropores and mesopores.

[0008] Furthermore, the mass ratio of thermoplastic resin to additives is 1:0.01-0.3.

[0009] Furthermore, the pre-carbonization conditions include: heating to the carbonization temperature at a rate of 1-10℃ / min, with the carbonization temperature being 800-1100℃, and holding at that temperature for 2-10 hours.

[0010] Further, the pulverized material is impregnated, including the following steps: The crushed material is immersed in an immersion solution, which includes a nitric acid solution with a concentration of 20%-60%.

[0011] It should be noted that the template method and nitric acid oxidation of this invention produce a synergistic effect: the nitric acid treatment occurs after pre-carbonization; the primary pores left by the template decomposition during pre-carbonization provide channels for the deep penetration of the nitric acid solution, allowing oxygen-containing functional groups to be uniformly introduced into the bulk phase of the material, rather than being limited to the surface. This improves the sodium storage capacity and rate performance of the material.

[0012] Furthermore, the coating agent includes a phenolic resin solution with a solid content of 40%-50%.

[0013] It should be noted that this invention uses phenolic resin, which is homologous to the core, as the coating agent. Compared with heterologous coating agents such as asphalt and glucose, the hard carbon structure formed after carbonization of phenolic resin is completely consistent with the core, eliminating the mismatch problem at the heterogeneous interface. This homologous coating not only effectively suppresses the side reactions between the electrolyte and the active material, but also avoids capacity loss caused by differences in the degree of graphitization in soft carbon coating layers (such as asphalt).

[0014] Furthermore, the pulverizing equipment for crushing pre-carbonized materials includes at least one of air jet mill, roller mill, and mechanical mill.

[0015] Furthermore, the coating agent accounts for 1%-20% of the mass of the dried material.

[0016] Furthermore, the conditions for carbonizing the mixture include: heating to the carbonization temperature at a heating rate of 1-10℃ / min, the carbonization temperature being 1000-1500℃, and holding at that temperature for 1-12 hours.

[0017] Furthermore, both pre-carbonization and carbonization require a protective atmosphere, which includes at least one of nitrogen, helium, and argon.

[0018] Furthermore, the particle size D50 of the pulverized material is controlled at 5-7µm.

[0019] Secondly, the high-capacity, high-rate resin-based hard carbon of the present invention is applied in a sodium-ion battery. The sodium-ion battery includes a negative electrode material, which includes high-capacity, high-rate resin-based hard carbon. The high-capacity, high-rate resin-based hard carbon is prepared according to the aforementioned method for preparing high-capacity, high-rate resin-based hard carbon based on a template method.

[0020] The beneficial effects of this invention are: Compared to biomass and petroleum-based precursors, resin-based precursors have relatively simple and controllable molecular structures. Furthermore, the molecular structures can be designed as needed to precisely construct adjustable pore structures and active sites at the molecular level, resulting in better rate capability and cycling stability in hard carbon materials. Hard carbon materials prepared using resin-based precursors exhibit high specific capacity, good electrochemical performance, and good consistency, demonstrating significant performance advantages. This invention involves adding relevant additives during the crosslinking and activation process of phenolic resin to ensure uniform distribution of the pore-forming agent within the material, precisely constructing the pore structure and increasing the material's reactive sites. The crosslinked resin is then pre-carbonized and pulverized to a suitable particle size. Subsequently, the pre-carbonized resin material is impregnated in a nitric acid solution. Nitric acid primarily introduces oxygen-containing functional groups (carboxyl, carbonyl, and nitro groups, etc.), which increase the active sites of the carbon material, providing more adsorption and storage sites for sodium ions, thereby enhancing the sodium storage capacity of the hard carbon.

[0021] To suppress graphitization, oxygen-containing functional groups connect precursor molecules through chemical or hydrogen bonds, forming a three-dimensional cross-linked network. During carbonization, this cross-linked structure inhibits the ordered stacking and graphitization of carbon layers, maintaining the disordered amorphous structure of hard carbon. This disordered structure facilitates the insertion and diffusion of sodium ions, improving sodium storage performance. During carbonization, oxygen-containing functional groups decompose to produce gases such as carbon dioxide (CO2) and carbon monoxide (CO). These gases accumulate within the hard carbon framework and escape, forming nanopores. These nanopores provide additional storage space for sodium ions, especially in the low-potential plateau region, where the pore-filling effect significantly enhances the capacity of hard carbon. Subsequent coating with phenolic resin solution improves material stability, suppresses battery-related side reactions, and enhances high and low temperature performance, while simultaneously increasing capacity and avoiding the capacity reduction caused by excessive soft carbon coating. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is the first charge-discharge curve of Embodiment 1 of the present invention at a current density of 0.1C; Figure 2 This is a SEM image of the high-capacity, high-rate resin-based hard carbon of Example 1 of the present invention; Figure 3 This is a graph showing the 5C cycle specific capacity and cycle retention rate of high-capacity, high-rate resin-based hard carbon as the negative electrode material for sodium-ion batteries in Embodiment 1 of the present invention. Figure 4 This is the Raman spectrum of the high-capacity, high-rate resin-based hard carbon of Example 1 of the present invention; Detailed Implementation The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0023] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0024] Unless otherwise specified, the equipment and materials used in the embodiments can be readily obtained from commercial companies.

[0025] It should be noted that some of the raw material information used in the examples and comparative examples is as follows: Thermoplastic resin: Phenolic resin is selected, manufactured by Zhejiang Zili Holding Polymer Chemical Materials Co., Ltd., and the grade is 4122-1.

[0026] Phenolic resin coating agent: solid content 50%, specifically phenolic resin solution, manufacturer is Yierfu Chemical, brand name is EV-2077D.

[0027] Asphalt: softening point 200℃, manufacturer is Hongyu Asphalt, grade is M-200.

[0028] High-speed mixer: Uses VC mixer.

[0029] Example 1 A method for preparing high-capacity, high-rate resin-based hard carbon based on a template method comprises the following steps: Step 1: Stir the thermoplastic resin in ethanol continuously until it dissolves to obtain a dissolved phenolic resin solution.

[0030] Add ZnCl2 to the dissolved phenolic resin solution and stir thoroughly. The thermoplastic resin and the additive are mixed in a mass ratio of 1:0.1. After stirring thoroughly, the resin solution is dried in an 80℃ oven. The dried resin is then placed under a UV lamp to allow it to be fully irradiated, so that the resin can be rapidly cross-linked and cured to obtain a cross-linked cured resin.

[0031] Step 2: Place the cross-linked cured resin obtained in step (1) into a carbonization box furnace for carbonization. Heat the resin to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1000℃. Hold the resin for 2 hours in a nitrogen atmosphere to obtain the pre-carbonized material.

[0032] Step 3: The pre-carbonized material obtained in step (2) is pulverized using an air jet mill, and the particle size D50 is controlled between 5-7µm to obtain pulverized material.

[0033] Step 4: Immerse the pulverized material obtained in step (3) in a 40% concentrated nitric acid solution. After thorough immersion, place it in a drying oven and dry at 80°C for 2 hours to obtain dried material.

[0034] Step 5: Add the dried material obtained in step (4) into a high-speed mixer and add phenolic resin coating agent. The mass of phenolic resin coating agent is 10% of the mass of the dried material to obtain a mixture.

[0035] Step 6: Place the mixture obtained in step (5) into a carbonization furnace for carbonization. Heat the mixture to the carbonization temperature at a rate of 3℃ / min. The carbonization temperature is 1400℃. Hold the mixture for 4 hours in an argon atmosphere to obtain high-capacity, high-rate resin-based hard carbon.

[0036] Example 2 A method for preparing high-capacity, high-rate resin-based hard carbon based on a template method comprises the following steps: Step 1: Stir the thermoplastic resin in ethanol continuously until it dissolves to obtain a dissolved phenolic resin solution.

[0037] Add FeCl3 to the dissolved phenolic resin solution and stir thoroughly. Mix the thermoplastic resin and the additive in a mass ratio of 1:0.1. After stirring thoroughly, dry the resin solution in an 80°C oven. Place the dried resin under a UV lamp to allow it to be fully irradiated, so that the resin can be rapidly cross-linked and cured to obtain a cross-linked cured resin.

[0038] Step 2: Place the cross-linked cured resin obtained in step (1) into a carbonization box furnace for carbonization. Heat the resin to the carbonization temperature at a rate of 6℃ / min. The carbonization temperature is 900℃. Hold the resin at the temperature for 4 hours in a nitrogen atmosphere to obtain the pre-carbonized material.

[0039] Step 3: The pre-carbonized material obtained in step (2) is crushed by roller mill, and the particle size D50 is controlled between 5-7µm to obtain crushed material.

[0040] Step 4: Immerse the pulverized material obtained in step (3) in a 50% concentrated nitric acid solution. After thorough immersion, place it in a drying oven and dry at 80°C for 2 hours to obtain dried material.

[0041] Step 5: Add the dried material obtained in step (4) into a high-speed mixer and add phenolic resin coating agent. The mass of phenolic resin coating agent is 15% of the mass of the dried material to obtain a mixture.

[0042] Step 6: Place the mixture obtained in step (5) into a carbonization furnace for carbonization. Heat the mixture to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1500℃. Hold the mixture for 2 hours in a nitrogen atmosphere to obtain high-capacity, high-rate resin-based hard carbon.

[0043] Example 3 A method for preparing high-capacity, high-rate resin-based hard carbon based on a template method comprises the following steps: Step 1: Stir the thermoplastic resin in ethanol continuously until it dissolves to obtain a dissolved phenolic resin solution.

[0044] Add the additive FeCl3 / ZnCl2 to the dissolved phenolic resin solution and stir thoroughly. The mass ratio of FeCl3 to ZnCl2 is 1:1. The mass ratio of thermoplastic resin to additive is 1:0.1. After stirring thoroughly, dry the resin solution in an 80℃ oven. Place the dried resin under a UV lamp to allow it to be fully irradiated, so that the resin can be rapidly cross-linked and cured to obtain cross-linked cured resin.

[0045] Step 2: Place the cross-linked cured resin obtained in step (1) into a carbonization box furnace for carbonization. Heat the resin to the carbonization temperature at a rate of 6℃ / min. The carbonization temperature is 800℃. Hold the resin at the temperature for 8 hours. The atmosphere is argon. The pre-carbonized material is obtained.

[0046] Step 3: The pre-carbonized material obtained in step (2) is pulverized using an air jet mill, and the particle size D50 is controlled between 5-7µm to obtain pulverized material.

[0047] Step 4: Immerse the pulverized material obtained in step (3) in a 60% concentrated nitric acid solution. After thorough immersion, place it in a drying oven and dry at 80°C for 2 hours to obtain dried material.

[0048] Step 5: Add the dried material obtained in step (4) into a high-speed mixer and add phenolic resin coating agent. The mass of phenolic resin coating agent is 12% of the mass of the dried material to obtain a mixture.

[0049] Step 6: Place the mixture obtained in step (5) into a carbonization furnace for carbonization. Heat the mixture to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1500℃. Hold the mixture for 2 hours in a nitrogen atmosphere to obtain high-capacity, high-rate resin-based hard carbon.

[0050] Example 4 A method for preparing high-capacity, high-rate resin-based hard carbon based on a template method comprises the following steps: Step 1: Stir the thermoplastic resin in ethanol continuously until it dissolves to obtain a dissolved phenolic resin solution.

[0051] Add the additive FeCl3 / ZnCl2 to the dissolved phenolic resin solution and stir thoroughly. The mass ratio of FeCl3 to ZnCl2 is 2:1. The mass ratio of thermoplastic resin to additive is 1:0.15. After stirring thoroughly, dry the resin solution in an 80℃ oven. Place the dried resin under a UV lamp to allow it to be fully irradiated, so that the resin can be rapidly cross-linked and cured to obtain cross-linked cured resin.

[0052] Step 2: Place the cross-linked cured resin obtained in step (1) into a carbonization box furnace for carbonization. Heat the resin to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1000℃. Hold the resin at the temperature for 4 hours in a nitrogen atmosphere to obtain the pre-carbonized material.

[0053] Step 3: The pre-carbonized material obtained in step (2) is pulverized by mechanical milling, and the particle size D50 is controlled between 5-7µm to obtain pulverized material.

[0054] Step 4: Immerse the pulverized material obtained in step (3) in a 60% concentrated nitric acid solution. After thorough immersion, place it in a drying oven and dry at 80°C for 2 hours to obtain dried material.

[0055] Step 5: Add the dried material obtained in step (4) into a high-speed mixer and add phenolic resin coating agent. The mass of phenolic resin coating agent is 5% of the mass of the dried material to obtain a mixture.

[0056] Step 6: Place the mixture obtained in step (5) into a carbonization furnace for carbonization. Heat the mixture to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1500℃. Hold the mixture for 2 hours in an argon atmosphere to obtain high-capacity, high-rate resin-based hard carbon.

[0057] Comparative Example 1 A method for preparing resin-based hard carbon, which, compared with Example 1, does not include any additives, but is otherwise the same as Example 1.

[0058] It consists of the following steps: Step 1: Stir the thermoplastic resin in ethanol continuously until dissolved to obtain a dissolved phenolic resin solution. Then, place it in an 80℃ oven to dry thoroughly. Place the dried resin under a UV lamp to allow it to be fully irradiated, so that the resin can quickly crosslink and cure, obtaining a crosslinked cured resin.

[0059] Step 2: Place the cross-linked cured resin obtained in step (1) into a carbonization box furnace for carbonization. Heat the resin to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1000℃. Hold the resin for 2 hours in a nitrogen atmosphere to obtain the pre-carbonized material.

[0060] Step 3: The pre-carbonized material obtained in step (2) is pulverized using an air jet mill, and the particle size D50 is controlled between 5-7µm to obtain pulverized material.

[0061] Step 4: Immerse the pulverized material obtained in step (3) in a 40% concentrated nitric acid solution. After thorough immersion, place it in a drying oven and dry at 80°C for 2 hours to obtain dried material.

[0062] Step 5: Add the dried material obtained in step (4) into a high-speed mixer and add phenolic resin coating agent. The mass of phenolic resin coating agent is 10% of the mass of the dried material to obtain a mixture.

[0063] Step 6: Place the mixture obtained in step (5) into a carbonization furnace for carbonization. Heat the mixture to the carbonization temperature at a rate of 3℃ / min. The carbonization temperature is 1400℃. Hold the mixture for 4 hours in an argon atmosphere to obtain resin-based hard carbon.

[0064] Comparative Example 2 A method for preparing resin-based hard carbon comprises the following steps: Step 1: Stir the thermoplastic resin in ethanol continuously until it dissolves to obtain a dissolved phenolic resin solution.

[0065] Add ZnCl2 to the dissolved phenolic resin solution and stir thoroughly. The thermoplastic resin and the additive are mixed in a mass ratio of 1:0.1. After stirring thoroughly, the resin solution is dried in an 80℃ oven. The dried resin is then placed under a UV lamp to allow it to be fully irradiated, so that the resin can be rapidly cross-linked and cured to obtain a cross-linked cured resin.

[0066] Step 2: Place the cross-linked cured resin obtained in step (1) into a carbonization box furnace for carbonization. Heat the resin to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1000℃. Hold the resin for 2 hours in an argon atmosphere to obtain the pre-carbonized material.

[0067] Step 3: The pre-carbonized material obtained in step (2) is crushed by roller mill, and the particle size D50 is controlled between 5-7µm to obtain crushed material.

[0068] Step 4: Immerse the pulverized material obtained in step (3) in a 40% concentrated hydrochloric acid solution. After thorough immersion, place it in a drying oven and dry at 80°C for 2 hours to obtain dried material.

[0069] Step 5: Add the dried material obtained in step (4) into a high-speed mixer and add phenolic resin coating agent. The mass of phenolic resin coating agent is 12% of the mass of the dried material to obtain a mixture.

[0070] Step 6: Place the mixture obtained in step (5) into a carbonization furnace for carbonization. Heat the mixture to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1500℃. Hold the mixture for 3 hours in a nitrogen atmosphere to obtain resin-based hard carbon.

[0071] Comparative Example 3 A method for preparing resin-based hard carbon comprises the following steps: Step 1: Stir the thermoplastic resin in ethanol continuously until it dissolves to obtain a dissolved phenolic resin solution.

[0072] Add ZnCl2 to the dissolved phenolic resin solution and stir thoroughly. The thermoplastic resin and the additive are mixed in a mass ratio of 1:0.1. After stirring thoroughly, the resin solution is dried in an 80℃ oven. The dried resin is then placed under a UV lamp to allow it to be fully irradiated, so that the resin can be rapidly cross-linked and cured to obtain a cross-linked cured resin.

[0073] Step 2: Place the cross-linked cured resin obtained in step (1) into a carbonization box furnace for carbonization. Heat the resin to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1000℃. Hold the resin for 2 hours in a nitrogen atmosphere to obtain the pre-carbonized material.

[0074] Step 3: The pre-carbonized material obtained in step (2) is pulverized using an air jet mill, and the particle size D50 is controlled between 5-7µm to obtain pulverized material.

[0075] Step 4: Immerse the pulverized material obtained in step (3) in a 40% concentrated nitric acid solution. After thorough immersion, place it in a drying oven and dry at 80°C for 2 hours to obtain dried material.

[0076] Step 5: Add the dried material obtained in step (4) into a high-speed mixer and add asphalt (softening point 200℃). The mass of the asphalt is 10% of the mass of the dried material to obtain the mixture.

[0077] Step 6: Place the mixture obtained in step (5) into a carbonization furnace for carbonization. Heat the mixture to the carbonization temperature at a rate of 3℃ / min. The carbonization temperature is 1400℃. Hold the mixture for 4 hours in an argon atmosphere to obtain resin-based hard carbon.

[0078] Comparative Example 4 A method for preparing resin-based hard carbon, compared with Example 1, except that step 4 of the impregnation treatment is not performed in this comparative example, and the rest is the same as in Example 1.

[0079] It consists of the following steps: Step 1: Stir the thermoplastic resin in ethanol continuously until it dissolves to obtain a dissolved phenolic resin solution.

[0080] Add ZnCl2 to the dissolved phenolic resin solution and stir thoroughly. The thermoplastic resin and the additive are mixed in a mass ratio of 1:0.1. After stirring thoroughly, the resin solution is dried in an 80℃ oven. The dried resin is then placed under a UV lamp to allow it to be fully irradiated, so that the resin can be rapidly cross-linked and cured to obtain a cross-linked cured resin.

[0081] Step 2: Place the cross-linked cured resin obtained in step (1) into a carbonization box furnace for carbonization. Heat the resin to the carbonization temperature at a rate of 5℃ / min. The carbonization temperature is 1000℃. Hold the temperature for 2 hours to obtain the pre-carbonized material.

[0082] Step 3: The pre-carbonized material obtained in step (2) is pulverized using an air jet mill, and the particle size D50 is controlled between 5-7µm to obtain pulverized material.

[0083] Step 4: Add the pulverized material obtained in step (3) into a high-speed mixer and add phenolic resin coating agent. The mass of phenolic resin coating agent is 10% of the mass of the pulverized material to obtain a mixture.

[0084] Step 5: Place the mixture obtained in step (4) into a carbonization furnace for carbonization. Heat the mixture to the carbonization temperature at a rate of 3℃ / min. The carbonization temperature is 1400℃. Hold the mixture for 4 hours to obtain high-capacity, high-rate resin-based hard carbon.

[0085] The resin-based hard carbon prepared in Examples 1-4 and Comparative Examples 1-3 were used as negative electrode materials for sodium-ion batteries, and battery performance was tested using the following methods: Following a mass ratio of hard carbon material: conductive carbon black: CMC (sodium carboxymethyl cellulose): SBR (styrene-butadiene rubber, 40% solid content) = 7:2:0.5:0.5, specifically weighing 0.05g of CMC, 0.2g of Super P (SP, conductive carbon black), 0.7g of resin-based hard carbon, and 0.5g of SBR, and adding an appropriate amount of deionized water, stirring until a uniform slurry is formed, and then uniformly coating it onto the surface of copper foil using a coater, drying it in a 100℃ forced-air drying oven for 8 hours, and then slicing the coated electrode sheet using a slicer. In an Ar atmosphere glove box, using the resin-based hard carbon electrode sheet as the negative electrode, a 1.0mol / L commercial electrolyte (prepared with a V:V ratio of NaPF6 / EC:DMC of 1:1), a sodium metal sheet as the counter electrode, and glass fiber as the separator, a CR2032 coin cell was fabricated, and then charge-discharge tests were conducted using a constant current charge-discharge mode at a current density of 0.1C.

[0086] The negative electrode of the full cell was made with hard carbon material: CMC:SP:SBR = 94%: 2%: 2.5%: 1.5% by mass, and the positive electrode was made with NFPP system. A 1Ah soft pack battery was made, and 5C constant current constant voltage charging and 5C constant current discharging were performed to test the cycle performance. The test results are shown in Table 1.

[0087] Table 1. Charge / discharge specific capacity and initial efficiency of sodium-ion batteries

[0088] As can be seen from Table 1, the resin-based hard carbon anode material obtained by implementing the present invention has a high specific capacity, of which the capacity of Example 1 reaches 331 mAh / g, with an initial efficiency of 90.55%, and the overall performance is the best.

[0089] In Examples 1-4, a template pore-forming agent was added to the materials during the crosslinking process of phenolic resin, and pores were formed during the pre-carbonization process. Subsequently, concentrated nitric acid was used to modify the resin hard carbon precursor to further enhance the disordered structure of the material and form nanopores. Subsequently, the surface of the material was further modified by phenolic resin solution to form a hard carbon material with high capacity and high rate performance. Comparison of Example 1 and Comparative Example 1: Comparative Example 1 did not add any pore-forming agent during the phenolic resin crosslinking process, and its charging capacity (309.72 mAh / g) was significantly lower than that of Example 1. This indicates that introducing a pore-forming agent during the crosslinking stage can construct a rich nanoporous structure during the pre-carbonization process, thereby improving the sodium storage capacity.

[0090] Comparison of Example 1 and Comparative Example 2: Comparative Example 2 used hydrochloric acid instead of nitric acid in the impregnation modification step, and its charging capacity (316.18 mAh / g) was lower than that of Example 1. This indicates that the oxygen-containing functional groups (such as carboxyl, carbonyl, nitro, etc.) introduced by nitric acid treatment can increase the active sites of carbon materials and suppress the graphitization tendency during the carbonization process, thereby improving the capacity.

[0091] Comparison of Example 1 and Comparative Example 3: Comparative Example 3 used high softening point asphalt (softening point 200℃) instead of phenolic resin as the coating agent, and its charging capacity (317.40 mAh / g) was lower than that of Example 1. This shows that using phenolic resin solution for surface coating can stabilize the material structure, suppress side reactions, and avoid the drawback of capacity loss caused by excessively thick asphalt coating layers.

[0092] Compared with Comparative Example 4, the charging capacity of Comparative Example 4 (without wetting treatment) was 318.45 mAh / g, which was significantly lower than that of Example 1 (331.57 mAh / g), indicating that the degree of disorder was lower and the number of active sites was less.

[0093] Examples 1-4 present schemes for pre-carbonization of phenolic resin after crosslinking with different types and proportions of template pore-forming agents. Through the synergistic effect of template pore-forming, nitric acid oxidation modification, and phenolic resin coating, the capacity and rate performance of hard carbon materials are simultaneously improved. Details are as follows: 1. The influence of pore-forming agent type Example 1: Using ZnCl2 as a pore-forming agent, the initial charge capacity was 331.57 mAh / g.

[0094] Example 2: Using FeCl3 as a pore-forming agent, the initial charge capacity was 327.81 mAh / g.

[0095] The results showed that, under the same addition ratio (1:0.1) and similar process conditions, ZnCl2 exhibited slightly better pore-forming effect than FeCl3. This is related to the stronger dehydration activation and pore-forming ability of ZnCl2 during the carbonization process.

[0096] 2. The effect of composite pore-forming agents Example 3: Using a composite pore-forming agent of FeCl3 and ZnCl2, the initial charging capacity was 323.33 mAh / g.

[0097] Examples 1 and 2: A single pore-forming agent was used, with capacities of 331.57 mAh / g and 327.81 mAh / g, respectively.

[0098] Although the capacity of Example 3 was slightly lower than that of Example 1, its first-coulombic efficiency reached 92.00%, the highest among all samples. This indicates that the composite pore-forming agent has unique advantages in regulating pore structure and reducing insoluble capacity loss, which is beneficial to improving the first-coulombic efficiency of the material.

[0099] 3. Effect of coating ratio Example 1: The coating ratio is 10%, and the initial charging capacity is 331.57 mAh / g.

[0100] Example 4: The coating ratio is 5%, and the initial charging capacity is 330.23 mAh / g.

[0101] The similar capacities of the two indicate that the phenolic resin coating layer can effectively perform surface modification within the 5%-10% coating range. Excessively high coating ratios (such as 15% in Example 2 and 12% in Example 3) did not lead to further capacity increases, suggesting that a moderate coating ratio (5%-10%) is more beneficial in balancing capacity and surface stability.

[0102] 4. Effect of pre-carbonization temperature Example 1 (pre-carbonization at 1000℃): Capacity 331.57 mAh / g Example 2 (pre-carbonized at 900°C): Capacity 327.81 mAh / g Example 3 (pre-carbonization at 800°C): Capacity 323.33 mAh / g Example 4 (pre-carbonization at 1000°C): Capacity 330.23 mAh / g The results show that a higher pre-carbonization temperature (1000℃) is beneficial for obtaining a higher sodium storage capacity. This is because the pore-forming agent is more fully activated at higher temperatures, resulting in more complete pore development.

[0103] Appendix Figure 1 The graph shows the first charge-discharge curve of the resin-based hard carbon material prepared in Example 1 at a current density of 0.1C, demonstrating that the prepared material has a rich closed-pore structure.

[0104] Appendix Figure 2 This is a SEM image of the resin-based hard carbon material prepared in Example 1. The coating layer is uniform and continuous, with no obvious agglomeration. This is beneficial for uniform electrode coating and sufficient electrolyte wetting.

[0105] Appendix Figure 3 The graphs show the 5C / 5C cycle specific capacity and 500-cycle retention rate of the sodium-ion battery anode materials in Example 1 and Comparative Example 1, demonstrating that the present invention improves the rate performance and cycle stability of the material through the synergistic effect of template pore formation, nitric acid modification and phenolic resin coating.

[0106] Appendix Figure 4 The image shows the Raman spectrum of the resin-based hard carbon from Example 1, where I... D / I G =1.15, the degree of defect and the degree of ordering are adjusted to improve capacity and rate performance.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-capacity, high-rate resin-based hard carbon based on a template method, characterized in that, Includes the following steps: Thermoplastic resin is dissolved, then additives are added and stirred thoroughly. The mixture is then dried and irradiated under a UV lamp to obtain cross-linked and cured resin. The cross-linked and cured resin is pre-carbonized to obtain pre-carbonized material. The pre-carbonized material is pulverized to obtain pulverized material. The pulverized material is impregnated and dried to obtain dried material. The dried material and coating agent are mixed to obtain a mixture. The mixture is carbonized to obtain high-capacity, high-ratio resin-based hard carbon.

2. The method for preparing high-capacity, high-rate resin-based hard carbon based on template method according to claim 1, characterized in that, Thermoplastic resins include phenolic resins.

3. The method for preparing high-capacity, high-rate resin-based hard carbon based on template method according to claim 1, characterized in that, Additives include ZnCl2 and / or FeCl3.

4. The method for preparing high-capacity, high-rate resin-based hard carbon based on template method according to claim 1, characterized in that, The mass ratio of thermoplastic resin to additives is 1:0.01-0.

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5. The method for preparing high-capacity, high-rate resin-based hard carbon based on template method according to claim 1, characterized in that, The pre-carbonization conditions include: heating to the carbonization temperature at a rate of 1-10℃ / min, carbonization temperature of 800-1100℃, and holding at that temperature for 2-10 hours.

6. The method for preparing high-capacity, high-rate resin-based hard carbon based on template method according to claim 1, characterized in that, The process of wetting the pulverized material includes the following steps: The crushed material is immersed in an immersion solution, which includes a nitric acid solution with a concentration of 20%-60%.

7. The method for preparing high-capacity, high-rate resin-based hard carbon based on template method according to claim 1, characterized in that, The coating agent includes a phenolic resin solution, and the mass of the coating agent accounts for 1%-20% of the mass of the dried material.

8. The method for preparing high-capacity, high-rate resin-based hard carbon based on template method according to claim 1, characterized in that, The pulverizing equipment for crushing pre-carbonized materials includes at least one of air jet mill, roller mill, and mechanical mill.

9. The method for preparing high-capacity, high-rate resin-based hard carbon based on template method according to claim 1, characterized in that, The conditions for carbonizing the mixture include: heating to the carbonization temperature at a rate of 1-10℃ / min, the carbonization temperature being 1000-1500℃, and holding at that temperature for 1-12 hours.

10. High-capacity, high-rate resin-based hard carbon used in sodium-ion batteries, characterized in that... Sodium-ion batteries include negative electrode materials, which include high-capacity, high-rate resin-based hard carbon. The high-capacity, high-rate resin-based hard carbon is prepared by a template-based method according to any one of claims 1-9.

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