Self-template preparation method of fluorinated phenolic resin derived hard carbon sodium ion battery negative electrode material

Abstract

The invention discloses a self-template preparation method of a fluorinated phenolic resin derived hard carbon sodium ion battery negative electrode material, and relates to the technical field of sodium ion battery materials. Fluorinated phenolic resin is synthesized by taking fluorophenol, common phenol and formaldehyde as raw materials; then the resin is carbonized at a high temperature in an inert atmosphere, and the hard carbon material with the graded porous structure (rich in closed holes) is prepared by a one-step method by utilizing the self-template effect of HF gas generated by C-F bond breakage in situ in the carbonization process. The method does not need an external template and a corrosive activator, and the process is simple and green. The prepared hard carbon material has ultrahigh sodium storage capacity, extremely high platform capacity and excellent rate capability and cycling stability, solves the problems of low platform capacity and low rate capability and cycling stability of the existing hard carbon negative electrode, and has wide application prospects in high-performance sodium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery materials technology, and in particular to a self-templating method for preparing a fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material. Background Technology

[0002] Hard carbon materials are considered one of the most promising anode materials for sodium-ion batteries due to their abundant sodium storage sites, large interlayer spacing, and low cost. Their capacity consists of a high-potential ramp capacity and a low-potential plateau capacity, with the plateau capacity being crucial to the overall energy density of the cell. Existing research indicates that the plateau capacity mainly originates from the filling of sodium ions within the closed pores of hard carbon and even the formation of near-metallic sodium clusters.

[0003] Currently, the mainstream methods for constructing closed pores in hard carbon rely on external template methods (such as MgO and ZnO templates) or chemical activation methods (such as KOH and K2CO3 activation). While these methods are effective, they have significant drawbacks: template agents are usually highly corrosive, requiring complex post-treatment (such as acid washing) for removal, which is energy-intensive and prone to causing structural damage; chemical activation is a violent process, making it difficult to precisely control pore size distribution and introducing numerous surface defects, leading to irreversible capacity loss and reduced rate performance and cycling stability. Therefore, developing a mild, post-treatment-free method for preparing hard carbon that can precisely control the closed-pore structure is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a self-templating method for preparing fluorinated phenolic resin-derived hard carbon sodium-ion battery anode materials, in order to solve the problems existing in the prior art, such as complex preparation process, easy damage to carbon structure, insufficient plateau capacity, low rate performance and cycle stability.

[0005] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of the present invention: a self-templating method for preparing a fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material, comprising the following steps: A mixed solution is obtained by mixing fluorophenolic compounds (i.e., fluorophenols), non-fluorophenolic compounds (i.e., common phenols), a catalyst, and water. Formaldehyde solution is added to the mixed solution to carry out a hydroxymethylation reaction, thereby obtaining a resin prepolymer solution; The resin prepolymer solution is subjected to a hydrothermal polymerization reaction to obtain fluorinated phenolic resin; The fluorinated phenolic resin is carbonized at high temperature under an inert atmosphere to obtain the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material.

[0006] The present invention utilizes fluorinated phenolic resin to prepare hierarchical porous hard carbon materials through a self-templating effect. Specifically, by leveraging the self-templating effect of HF gas generated in situ during the carbonization process of CF bond breaking, a hard carbon material with a hierarchical porous structure (rich in closed pores) is prepared in one step. This method requires no external template or corrosive activator, and the process is simple and environmentally friendly. The prepared hard carbon material exhibits ultra-high sodium storage capacity, extremely high plateau capacity, and excellent rate performance and cycle stability, solving the problems of low plateau capacity, poor rate performance, and low cycle stability of existing hard carbon anodes, and has broad application prospects in high-performance sodium-ion batteries.

[0007] Furthermore, the proportion of the fluorophenolic compound in the sum of the mass of the fluorophenolic compound and the non-fluorophenolic compound is 5 to 100 wt%, preferably 10 to 30 wt%.

[0008] Furthermore, the fluorophenolic compounds include one or more of 2-fluorophenol, 3-fluorophenol, 2,3-difluorophenol, 2,4-difluorophenol, and 2,6-difluorophenol.

[0009] Furthermore, the non-fluorinated phenolic compounds include one of phenol, o-cresol, and p-cresol.

[0010] Furthermore, the catalyst includes ammonia, sodium hydroxide solution, or potassium hydroxide solution, preferably ammonia.

[0011] Preferably, the concentration of the ammonia water is 25-28 wt%.

[0012] Furthermore, the ratio of the sum of the masses of the fluorophenolic compounds and the non-fluorophenolic compounds to the volume of the catalyst is 1 g: 1 to 3 mL, preferably 1 g: 2.14 mL.

[0013] Furthermore, the ratio of the sum of the masses of the fluorophenolic compounds and the non-fluorophenolic compounds to the volume of the water is 1–4 g:100 mL, preferably 3.5 g:100 mL.

[0014] Furthermore, the concentration of the formaldehyde solution is 37–40 wt%.

[0015] Furthermore, the ratio of the sum of the molar amounts of the fluorophenolic compounds and the non-fluorophenolic compounds to the molar amount of formaldehyde contained in the formaldehyde solution is 1:1 to 2.5, preferably 1:1.5.

[0016] Furthermore, the hydroxymethylation reaction takes 0.5 to 2 hours, preferably 30 minutes.

[0017] Furthermore, the hydroxymethylation reaction is carried out at room temperature (20–30 °C).

[0018] Furthermore, the temperature of the hydrothermal polymerization reaction is 90–120 °C, preferably 100 °C; the time is 6–24 hours, preferably 12 hours.

[0019] Furthermore, the high-temperature carbonization temperature is 1000–1600 °C, preferably 1300 °C; the time is 1–6 hours, preferably 2 hours.

[0020] During the carbonization process, fluorine atoms in the fluorinated phenolic resin continuously escape in the form of HF, and in situ and dynamically etch a hierarchical pore structure from mesopores to closed pores in the carbon skeleton. No template removal post-processing is required, and there is no fluorine element residue in the final product. All F elements escape in gaseous form, thus obtaining a hard carbon anode material with a large number of pores.

[0021] Furthermore, the heating rate of the high-temperature carbonization is 1 to 10 °C / min, preferably 5 °C / min.

[0022] Furthermore, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.

[0023] Furthermore, after the hydrothermal polymerization reaction is completed, the reaction product is further subjected to centrifugation, washing, and drying steps.

[0024] Furthermore, the washing process specifically involves alternating between washing with water and anhydrous ethanol at least three times each.

[0025] Furthermore, the drying temperature is 60–100 °C, preferably 80 °C; the drying time is 6–12 hours, preferably 12 hours.

[0026] The second technical solution of the present invention: a fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material prepared according to the above-mentioned self-templating preparation method of fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material.

[0027] Furthermore, the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material has a hierarchical pore structure consisting of micropores, mesopores, and closed pores, wherein the closed pore volume is greater than 0.013 cm³. 3 / g, with closed-pore diameters of 1.17–1.21 nm.

[0028] The plateau capacity of the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material of the present invention is higher than 300 mAh / g.

[0029] Furthermore, the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material does not contain fluorine.

[0030] The third technical solution of the present invention: the application of the above-mentioned fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material in the preparation of sodium-ion battery anodes.

[0031] The fourth technical solution of the present invention: a method for preparing a sodium-ion battery negative electrode, comprising the following steps: The above-mentioned fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material is mixed with sodium alginate and water to obtain an electrode slurry; the electrode slurry is coated on a current collector, dried, and then pressed into a sheet to obtain the sodium-ion battery anode.

[0032] Furthermore, the mass ratio of the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material to the sodium alginate is 8:2-9:1.

[0033] The fifth technical solution of the present invention: a sodium-ion battery negative electrode prepared according to the above preparation method.

[0034] The sixth technical solution of the present invention: a sodium-ion battery, wherein the above-mentioned sodium-ion electrode negative electrode is used as the negative electrode.

[0035] The present invention discloses the following technical effects: (1) Process innovation and greening: This invention uses fluorinated phenolic resin as a precursor, and generates HF gas in situ through CF bond breaking during carbonization, which plays a role in "self-pore creation". This method completely avoids the use of external hard / soft templates or strong corrosive chemical activators, simplifies the process, reduces costs, and generates no polluting waste liquid. It is a green and efficient preparation method.

[0036] (2) Strong structural controllability: By precisely controlling the type, ratio and carbonization process parameters of fluorophenol monomers, the generation temperature, rate and amount of HF can be controlled, thereby achieving precise control of the pore size distribution, closed pore volume and surface chemical state of hard carbon materials, providing a solid foundation for optimizing its sodium storage performance.

[0037] (3) Excellent product performance: The hard carbon anode material prepared by this invention has an ultra-high reversible specific capacity (up to 445.8 mAh / g), an extremely high plateau capacity (up to 333.4 mAh / g, accounting for 75% of the total capacity), and excellent rate performance (maintaining 312.8 mAh / g at 1500 mAh / g) and cycle stability (capacity retention rate up to 85.6% after 200 cycles). The comprehensive performance indicators are at the leading level.

[0038] (4) Broad application prospects: The excellent performance of the hard carbon anode material prepared by this invention makes it widely applicable in high-performance sodium-ion batteries, especially suitable for large-scale energy storage, electric vehicles and smart grids where high energy density, power density and cycle life are required. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a SEM image of the 2,3-2FPR-HC hard carbon material prepared in Example 1 of the present invention; Figure 2 The image shows an HRTEM image of the 2,3-2FPR-HC hard carbon material prepared in Example 1 of this invention. Figure 3 XPS image of the 2,3-2FPR-HC hard carbon material prepared in Example 1 of this invention; Figure 4 The figures show the nitrogen adsorption-desorption curves and pore size distribution diagrams of the hard carbon materials prepared in Examples 1, 2 and Comparative Example 1 of this invention, where a is the nitrogen adsorption-desorption curve and b is the pore size distribution diagram. Figure 5 A comparison diagram of the closed-pore size and volume of the hard carbon sodium-ion battery anode materials prepared in Example 1, Example 2 and Comparative Example 1; Figure 6 The first charge-discharge curve of a sodium-ion battery assembled using the hard carbon material prepared in Example 1 of this invention is shown. Figure 7 The rate performance diagram shows the sodium-ion battery assembled using the hard carbon material prepared in Example 1 of this invention. Figure 8 The diagram shows the cycle performance of a sodium-ion battery assembled using the hard carbon material prepared in Example 1 of this invention. Detailed Implementation

[0041] 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.

[0042] 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. Any stated value or intermediate value within a stated range, as well as each smaller range between 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In the following embodiments and comparative examples of the present invention, room temperature refers specifically to 20–30 °C.

[0048] Unless otherwise specified, all raw materials used in the following embodiments and comparative examples of the present invention are commercially available products, and the concentration of ammonia water is 28 wt%.

[0049] Example 1 A self-templating method for preparing a fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material, comprising the following steps: (1) Mixing raw materials: Weigh 3.5 g of 2,3-difluorophenol into a beaker, add 7.5 mL of ammonia and 300 mL of deionized water, and stir magnetically for 30 minutes at room temperature to obtain a mixed solution.

[0050] (2) Hydroxymethylation reaction: Add 5 mL of formaldehyde solution (37 wt%) to the above mixed solution and continue to stir magnetically at room temperature for 30 minutes to obtain resin prepolymer solution.

[0051] (3) Hydrothermal polymerization reaction: The above resin prepolymer solution was transferred to a 200 mL polytetrafluoroethylene-lined high-pressure reactor. The reactor was placed in an oven and reacted at 100 °C for 12 hours. After the reaction was completed, it was allowed to cool naturally to room temperature. The obtained product was poured into a centrifuge tube and centrifuged at 8000 rpm. The supernatant was discarded. The precipitate was washed three times each with deionized water and anhydrous ethanol. The washed product was transferred to a petri dish and dried in a vacuum drying oven at 80 °C for 12 hours to obtain fluorinated phenolic resin solid, denoted as 2,3-2FPR.

[0052] (4) High-temperature carbonization: The above-mentioned 2,3-2FPR resin was placed in an alumina boat, and then placed in the center of a tube furnace. High-purity nitrogen was introduced for 30 minutes to purge the air. Then, under nitrogen atmosphere protection, the temperature was programmed to reach 1300 ℃ at a heating rate of 5 ℃ / min, and held at this temperature for 2 hours. After high-temperature carbonization, the material was naturally cooled to room temperature, and then the product was removed and ground to obtain the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material, denoted as 2,3-2FPR-HC.

[0053] Example 2 A self-templating method for preparing a fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material, comprising the following steps: (1) Mixing raw materials: Weigh 3.5 g of 3-fluorophenol into a beaker, add 7.5 mL of ammonia and 300 mL of deionized water, and stir magnetically for 30 minutes at room temperature to obtain a mixed solution.

[0054] (2) Hydroxymethylation reaction: Add 5 mL of formaldehyde solution (37 wt%) to the above mixed solution and continue to stir magnetically at room temperature for 30 minutes to obtain resin prepolymer solution.

[0055] (3) Hydrothermal polymerization reaction: The above resin prepolymer solution was transferred to a 200 mL polytetrafluoroethylene-lined high-pressure reactor. The reactor was placed in an oven and reacted at 100 °C for 12 hours. After the reaction was completed, it was allowed to cool naturally to room temperature. The obtained product was poured into a centrifuge tube and centrifuged at 8000 rpm. The supernatant was discarded. The precipitate was washed three times each with deionized water and anhydrous ethanol. The washed product was transferred to a petri dish and dried in a vacuum drying oven at 80 °C for 12 hours to obtain fluorinated phenolic resin solid, denoted as 3-FPR.

[0056] (4) High-temperature carbonization: The above-mentioned 3-FPR resin was placed in an alumina boat, and then placed in the center of a tube furnace. High-purity nitrogen was introduced for 30 minutes to purge the air. Then, under nitrogen atmosphere protection, the temperature was programmed to reach 1300 ℃ at a heating rate of 5 ℃ / min, and held at this temperature for 2 hours. After the high-temperature carbonization was completed, the product was naturally cooled to room temperature, removed, and ground to obtain the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material, denoted as 3-FPR-HC.

[0057] Comparative Example 1 A method for preparing a phenolic resin-derived hard carbon sodium-ion battery anode material, comprising the following steps: (1) Mixing raw materials: Weigh 3.5 g of phenol into a beaker, add 7.5 mL of ammonia and 300 mL of deionized water, and stir magnetically for 30 minutes at room temperature to obtain a mixed solution.

[0058] (2) Hydroxymethylation reaction: Add 5 mL of formaldehyde solution (37 wt%) to the above mixed solution and continue to stir magnetically at room temperature for 30 minutes to obtain resin prepolymer solution.

[0059] (3) Hydrothermal polymerization reaction: The above resin prepolymer solution was transferred to a 200 mL polytetrafluoroethylene-lined high-pressure reactor. The reactor was placed in an oven and reacted at 100 °C for 12 hours. After the reaction was completed, it was allowed to cool naturally to room temperature. The obtained product was poured into a centrifuge tube and centrifuged at 8000 rpm. The supernatant was discarded. The precipitate was washed three times each with deionized water and anhydrous ethanol. The washed product was transferred to a petri dish and dried in a vacuum drying oven at 80 °C for 12 hours to obtain solid phenolic resin, denoted as PR.

[0060] (4) High-temperature carbonization: The above-mentioned PR resin was placed in an alumina boat, and then placed in the center of a tube furnace. High-purity nitrogen was introduced for 30 minutes to purge the air. Then, under nitrogen atmosphere protection, the temperature was programmed to reach 1300℃ at a heating rate of 5℃ / min, and held at this temperature for 2 hours. After the high-temperature carbonization was completed, the product was naturally cooled to room temperature, removed, and ground to obtain the phenolic resin-derived hard carbon sodium-ion battery anode material, denoted as PR-HC.

[0061] Test Example 1 Characterization data: Figure 1 The image shows a SEM image of the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material 2,3-2FPR-HC prepared in Example 1. It can be seen that the surface has obvious porous channel structure.

[0062] Figure 2The image shows the HRTEM image of the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material 2,3-2FPR-HC prepared in Example 1, illustrating its closed-pore structure.

[0063] Figure 3 The XPS image shows the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material 2,3-2FPR-HC prepared in Example 1. It can be seen that there is no F element in 2,3-2FPR-HC, indicating that all F was released during the preparation process.

[0064] Figure 4 The figures show the nitrogen adsorption-desorption curves and pore size distribution of the hard carbon sodium-ion battery anode materials prepared in Examples 1, 2, and Comparative Example 1, where a is the nitrogen adsorption-desorption curve and b is the pore size distribution. It can be seen that Examples 1 and 2 have a hierarchical pore structure consisting of micropores, mesopores, and closed pores. Furthermore, it can be observed that the specific surface area and pore structure of the hard carbon materials change significantly with different phenolic resins, with the number of micropores in Example 1 increasing dramatically.

[0065] Figure 5 The diagram shows a comparison of the closed-pore diameter and volume of the hard carbon sodium-ion battery anode materials prepared in Examples 1, 2 and Comparative Example 1. It can be seen that the closed-pore volume and closed-pore size of the hard carbon materials change significantly with different phenolic resins, with Example 1 having the largest closed-pore diameter and closed-pore volume.

[0066] Application Example 1 The preparation steps for the negative electrode of a sodium-ion battery are as follows: 0.09 g of hard carbon material prepared in each example or comparative example and 0.01 g of sodium alginate were dissolved in 500 μL of deionized water to obtain an electrode slurry. The obtained electrode slurry was uniformly coated onto an aluminum current collector using a 150 μm thick doctor blade. After drying, it was pressed on a tablet press to obtain a sodium-ion battery negative electrode sheet with a diameter of 11 mm. The loading of hard carbon material was 1 mg / cm³. 2 .

[0067] The assembly steps for a sodium-ion battery are as follows: The above-mentioned sodium-ion battery negative electrode was placed on the positive side of the half-cell, with a metallic sodium sheet as the counter electrode. A commercially available sodium-ion electrolyte (1 M NaPF6 in diglyme, i.e., NaPF6 dissolved in diethylene glycol dimethyl ether at a concentration of 1 M) was used as the electrolyte. A GF / D membrane was used as the separator. A CR2032 coin cell was assembled under an argon atmosphere, and electrochemical performance tests were conducted within the voltage range of 0.01–2.5 V. The test results are shown in Table 1 and [Table data would be inserted here]. Figures 6-8 .

[0068] Figure 6The first charge-discharge curve of a sodium-ion battery prepared using the hard carbon material prepared in Example 1 of this invention is shown. Figure 7 The rate performance diagram shows the sodium-ion battery prepared using the hard carbon material prepared in Example 1 of this invention. Figure 8 The diagram shows the cycle performance of a sodium-ion battery prepared using the hard carbon material prepared in Example 1 of this invention.

[0069] Depend on Figure 6 It can be seen that the hard carbon material prepared in Example 1 exhibits an ultra-high initial reversible specific capacity of 445.8 mAh / g at a current density of 0.1 C (1 C = 300 mAh / g), which is higher than that of most hard carbon anodes reported in the current technology. Furthermore, it also possesses an extremely high plateau capacity (the plateau capacity specifically refers to the capacity <0.1 V, which is 333.4 mAh / g, accounting for 75% of the total capacity). In addition, from... Figure 7 It can be seen that the hard carbon material prepared in Example 1 also exhibits excellent rate performance, maintaining a specific capacity of over 300 mAh / g (specifically 312.8 mAh / g) even at a high current density of 5 C (5C = 1500 mAh / g). From Figure 8 It can be seen that the hard carbon material prepared in Example 1 also has excellent cycling stability, with a capacity retention of 85.6% after 200 cycles.

[0070] Table 1. Electrochemical performance of hard carbon sodium-ion battery anode materials prepared in each example and comparative example. The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a self-templating material for a fluorinated phenolic resin-derived hard carbon sodium-ion battery anode, characterized in that, Includes the following steps: A mixed solution is obtained by mixing fluorophenolic compounds, non-fluorophenolic compounds, a catalyst, and water. Formaldehyde solution is added to the mixed solution to carry out a hydroxymethylation reaction, thereby obtaining a resin prepolymer solution; The resin prepolymer solution is subjected to a hydrothermal polymerization reaction to obtain fluorinated phenolic resin; The fluorinated phenolic resin is carbonized at high temperature under an inert atmosphere to obtain the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material.

2. The self-templating method for preparing the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material as described in claim 1, characterized in that, The fluorophenolic compound accounts for 5 to 100 wt% of the total mass of the fluorophenolic compound and the non-fluorophenolic compound.

3. The self-templating method for preparing the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material as described in claim 2, characterized in that, The fluorophenolic compounds include one or more of 2-fluorophenol, 3-fluorophenol, 2,3-difluorophenol, 2,4-difluorophenol, and 2,6-difluorophenol. And / or, the non-fluorinated phenolic compounds include one of phenol, o-cresol, and p-cresol.

4. The self-templating method for preparing the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material as described in claim 1, characterized in that, The catalyst includes ammonia water, sodium hydroxide solution, or potassium hydroxide solution; And / or, the ratio of the sum of the masses of the fluorophenolic compounds and the non-fluorophenolic compounds to the volume of the catalyst is 1 g: 1 to 3 mL; And / or, the concentration of the formaldehyde solution is 37–40 wt%; And / or, the ratio of the sum of the molar amounts of the fluorophenolic compounds and the non-fluorophenolic compounds to the molar amount of formaldehyde contained in the formaldehyde solution is 1:1 to 2.

5.

5. The self-templating method for preparing the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material as described in claim 1, characterized in that, The hydroxymethylation reaction takes 0.5 to 2 hours; And / or, the hydrothermal polymerization reaction is carried out at a temperature of 90–120 °C for a time of 6–24 hours; And / or, the high-temperature carbonization temperature is 1000–1600 °C, and the time is 1–6 hours.

6. A fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material prepared by a self-templating method according to any one of claims 1 to 5.

7. The application of the fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material as described in claim 6 in the preparation of sodium-ion battery anodes.

8. A method for preparing a sodium-ion battery negative electrode, characterized in that, Includes the following steps: The fluorinated phenolic resin-derived hard carbon sodium-ion battery anode material of claim 6 is mixed with sodium alginate and water to obtain an electrode slurry; the electrode slurry is coated onto a current collector, dried, and then pressed into a sheet to obtain the sodium-ion battery anode.

9. A sodium-ion battery negative electrode prepared by the preparation method according to claim 8.

10. A sodium-ion battery, characterized in that, The sodium ion electrode negative electrode as described in claim 9 is used as the negative electrode.

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