Resin-based hard carbon based on steric effect of aromatic group and preparation method and application thereof

Abstract

The application provides resin-based hard carbon based on the steric hindrance effect of aromatic groups and a preparation method and application thereof, and belongs to the technical field of negative electrode materials of sodium ion batteries. The application adopts aldehyde monomers containing aromatic groups to be condensed with phenolic monomers to obtain a phenolic resin hard carbon precursor, and then sequentially undergoes post-curing and high-temperature pyrolysis carbonization to obtain resin-based hard carbon based on the steric hindrance effect of aromatic groups. The aromatic groups contained in the side chain of the phenolic resin can change the steric hindrance of the polymer and construct pi-pi stacking, improve the internal free volume of the resin and the rigidity of the molecular chain; and then can effectively inhibit the excessive graphitization of the carbon layer in the subsequent carbonization process, and promote the formation of a large number of closed pores. The steric hindrance strategy of the aromatic groups provided by the application has a positive effect on the regulation of the microstructure of the hard carbon material, and the resin-based hard carbon material as the negative electrode of the sodium ion battery exhibits high specific capacity and first coulomb efficiency, and also has good rate performance and cycle stability characteristics.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion battery negative electrode materials, and particularly relates to resin-based hard carbon based on the steric hindrance effect of aromatic groups, and a preparation method and application thereof. Background Art

[0002] Since its commercialization, lithium-ion batteries have played a very important role in new energy fields such as mobile power supplies and electric vehicles; however, with the increasing demand for energy storage, the problems of limited and uneven distribution of lithium resources have gradually become prominent. Sodium ions are highly similar to lithium ions. At the same time, sodium elements have large reserves, wide distribution, and low prices, which can alleviate the problem of lithium resource shortage. Therefore, the development of sodium-ion batteries is more suitable for the construction of the next generation of large-scale energy storage systems. However, current sodium-ion batteries are severely limited by the negative electrode materials, especially the traditional graphite negative electrode, which has different sodium and lithium storage mechanisms and cannot store sodium with larger ion radius. + To achieve effective electrochemical storage, the development of novel anode materials has become a research hotspot in this field. Hard carbon, composed of disordered, chaotically layered graphite crystallites and closed pores formed by curling nanodomains, features small crystallite size, large interlayer spacing, and a high number of micrometer-scale closed pores, making it a promising anode material for sodium-ion batteries. However, current resin-derived hard carbon anode materials suffer from low specific capacity, low initial coulombic efficiency, and poor rate performance. Furthermore, due to the influence of the polymer cross-linked structure, the technical barrier to molecular-level manipulation of the microstructure of resin-derived hard carbon is high. To address these issues, research teams at home and abroad have undertaken extensive work. Hu Yongsheng's research group used ethanol vapor to create pores in a cross-linked phenolic resin during a solvothermal process. These pores were then converted into closed pores during a subsequent high-temperature carbonization process, increasing the sodium storage capacity to 410 mAh / g (ACS Energy Lett. 2019, 4, 2608-2612). Although this method improves the electrochemical performance of resin-based carbon materials to a certain extent, the ethanol solvothermal method is limited by the reactor process, making it unsuitable for large-scale production. Shinichi Komaba's team used polyvinyl alcohol as a pore-forming agent, formaldehyde and maleic anhydride as a cross-linking agent and catalyst in a liquid phenolic resin system to prepare a microporous phenolic resin precursor for the preparation of hard carbon. The hard carbon material exhibited a high specific capacity of 386mAh / g at a current density of 10mA / g (ACSAppl.EnergyMater.2020,3,135-140), but its high specific surface area resulted in a low first coulombic efficiency, which made it difficult to meet commercial applications. Therefore, it is urgent to develop a method for preparing a resin-based hard carbon material with a simple process and easy commercialization, so that the prepared hard carbon material has both high sodium storage capacity and first coulombic efficiency, as well as good cycle performance and rate performance. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a resin-based hard carbon based on the steric hindrance effect of aromatic groups, and a preparation method and application thereof, aiming to solve at least one technical problem among the background technologies.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention provides a method for preparing resin-based hard carbon based on the steric hindrance effect of aromatic groups, the preparation method comprising:

[0006] Step (1): stirring and mixing an aldehyde compound containing an aromatic group, a phenolic compound, ethanol and a sodium hydroxide solution, heating and polycondensing them in a condensation reflux device until they become gelled, and air-drying them at room temperature to obtain a phenolic resin containing a steric hindrance effect of an aromatic ring group;

[0007] Step (2): transferring the phenolic resin obtained in step (1) to a muffle furnace for post-curing, washing with deionized water, filtering, and drying;

[0008] Step (3): The phenolic resin obtained in step (2) is subjected to high-temperature pyrolysis and carbonization under the protection of an inert atmosphere to obtain the resin-based hard carbon material.

[0009] Preferably, the phenolic resin containing the steric hindrance effect of the aromatic ring group obtained in step (1) has the structure shown in the following formulas (1) to (3):

[0010]

[0011] In formulae 1 to 3, R represents a side chain group containing an aromatic ring.

[0012] Preferably, the aromatic ring side chain group R contained in the phenolic resin has a structure as shown in the following formulas (1) to (4):

[0013]

[0014] Preferably, the thermal decomposition temperature of the aromatic ring side chain group R is 400-600°C.

[0015] Preferably, the molar ratio of the aldehyde compound, the phenolic compound and the sodium hydroxide in step (1) is 1.25:1:0.55.

[0016] Preferably, the heating polycondensation temperature in step (1) is 60° C., and the heating polycondensation time is 10-25 h.

[0017] Preferably, the post-curing temperature of step (2) is 200° C., and the post-curing time is 2 hours.

[0018] Preferably, the high-temperature pyrolysis carbonization temperature of step (3) is 1200-1500° C., and the carbonization time is 1-3 hours.

[0019] The second aspect of the present invention provides resin-based hard carbon based on the steric hindrance effect of aromatic groups obtained by the above preparation method.

[0020] The third aspect of the present invention provides the use of the resin-based hard carbon based on the steric hindrance effect of the aromatic group obtained by the above preparation method in the preparation of sodium ion battery negative electrode materials.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] (1) The preparation process of the present invention is simple, the hard carbon yield is high, and large-scale production is easy to achieve.

[0023] (2) The present invention introduces an aldehyde compound containing an aromatic group to undergo a polycondensation reaction with a phenolic compound to form a phenolic resin with a large side group, thereby adjusting the steric hindrance of the polymer side chain and increasing the spatial free volume of the resin, thereby facilitating the formation of a richer micron-scale closed-pore structure during the carbonization process of the phenolic resin and improving the reversible sodium storage capacity of the resin-based hard carbon;

[0024] (3) The aromatic side chain groups introduced in the present invention have a relatively high thermal stability temperature (400-600°C) and construct π-π stacking to enhance the rigidity of the molecular chain, which can improve the stability of the carbon skeleton structure during the high-temperature carbonization process of phenolic resin, reduce the number of cracking and rearrangement, and effectively inhibit the excessive graphitization of the carbon layer, forming a carbon layer with a large interlayer spacing and short-range disorder, and promote the intercalation / deintercalation and diffusion of sodium ions, thereby improving the cycle stability and rate performance of hard carbon.

[0025] Therefore, the present invention provides a method for preparing resin-based hard carbon based on the steric hindrance effect of aromatic groups, which enables the hard carbon material to have both high sodium storage capacity and first coulombic efficiency, as well as good cycle performance and rate performance, which is conducive to promoting the industrialization process of sodium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The infrared spectra of the phenolic resin containing vinylphenyl side chain groups prepared in Example 1 of the present invention at different pyrolysis temperatures;

[0027] Figure 2 This is a first cycle charge and discharge curve diagram of the battery prepared in Example 1 of the present invention;

[0028] Figure 3 This is a rate performance curve of the battery prepared in Example 1 of the present invention;

[0029] Figure 4This is a cycle stability curve of the battery prepared in Example 1 of the present invention.

[0030] Figure 5 This is a charge and discharge curve diagram of the first cycle of the battery prepared in Comparative Example 1 of the present invention;

[0031] Figure 6 This is a rate performance curve of the battery prepared in Comparative Example 1 of the present invention;

[0032] Figure 7 This is a cycle stability curve of the battery prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the examples. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not intended to limit the present invention. The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0034] Example 1

[0035] 1) 2 g of resorcinol and 9 mL of anhydrous ethanol were added to a three-necked flask. After the resorcinol was completely dissolved, 2.8 mL of cinnamaldehyde was added. After stirring for 10 minutes, 10 mL of a 1 mol / L sodium hydroxide aqueous solution was added. The mixture was heated at 60° C. under a condensation reflux apparatus for 20 hours, and finally polycondensed until gelation occurred. The molecular structure of the gel product of step 1) is shown below:

[0036]

[0037] Wherein, R is a vinylphenyl side chain group.

[0038] 2) The gel product obtained in step 1) was air-dried at room temperature, then transferred to a muffle furnace and cured at 200° C. for 2 h. After cooling to room temperature, the powder was ground into powder, washed with deionized water, and filtered. The powder was then dried in a forced air oven at 80° C. for 24 h to obtain a phenolic resin containing vinylphenyl side chain groups.

[0039] 3) The phenolic resin obtained in step 2) is carbonized at 1400° C. for 1 hour under an argon inert atmosphere to obtain the resin-based hard carbon material based on the steric hindrance effect of the vinylphenyl group.

[0040] 4) The resin-based hard carbon material obtained in step 3) is used as the negative electrode, metallic sodium is used as the counter electrode, glass fiber is used as the separator, and 1MNaPF6 in DIGLYME (diethylene glycol dimethyl ether) is used as the electrolyte, and a sodium ion battery is assembled under an argon atmosphere.

[0041] Figure 1The infrared spectra of the phenolic resin containing vinylphenyl side chain groups obtained in Example 1 at different pyrolysis temperatures show that the characteristic infrared peak of the vinylphenyl group (~699cm -1 ) still exists at 400-600℃, proving that it effectively improves the thermal stability of the carbon skeleton.

[0042] Figure 2 The first cycle charge and discharge curve of the resin-based hard carbon material based on the steric hindrance effect of the vinylphenyl group obtained in Example 1 when applied to a sodium ion battery shows that the hard carbon negative electrode material for the sodium ion battery has a first coulombic efficiency of up to 88.5% and a reversible specific capacity of 340.3 mAh / g.

[0043] Figure 3 The rate performance curve of the resin-based hard carbon material based on the steric hindrance effect of the vinylphenyl group obtained in this embodiment 1 is applied to sodium ion batteries. It can be seen that the reversible specific capacity of the sodium ion battery hard carbon negative electrode material at a current density of 5C (1C = 30mA / g) is 210.7mAh / g.

[0044] Figure 4 This is the cycle stability curve of the resin-based hard carbon material based on the steric hindrance effect of the vinylphenyl group obtained in Example 1 applied to sodium ion batteries. It can be seen that the sodium ion battery hard carbon negative electrode material can be stably cycled for 1000 cycles at a current density of 2C, and the cycle capacity retention rate is higher than 86.4%.

[0045] Compared with Comparative Example 1, Example 1 can significantly improve the comprehensive electrochemical performance of its resin-based hard carbon negative electrode material due to the steric hindrance effect of the vinylphenyl group.

[0046] Comparative Example 1

[0047] 1) 2 g of resorcinol and 9 mL of anhydrous ethanol were added to a three-necked flask. After the resorcinol was completely dissolved, 1.6 mL of a 37 wt% formaldehyde solution was added. After stirring for 10 minutes, 10 mL of a 1 mol / L sodium hydroxide aqueous solution was added. The mixture was heated at 60° C. under a reflux apparatus for 20 hours and finally polycondensed until it gelled.

[0048] 2) The gel product obtained in step 1) is air-dried at room temperature, then transferred to a muffle furnace and cured at 200° C. for 2 h. After cooling to room temperature, the powder is ground into powder, washed with deionized water, filtered, and dried in a forced air oven at 80° C. for 24 h to obtain a phenolic resin without any aromatic ring side chain group modification.

[0049] 3) The phenolic resin obtained in step 2) is carbonized at 1400° C. for 1 hour under an argon inert atmosphere to obtain the resin-based hard carbon material without any aromatic ring side chain group modification.

[0050] 4) The resin-based hard carbon material obtained in step 3) is used as the negative electrode, metallic sodium is used as the counter electrode, glass fiber is used as the separator, and 1MNaPF6 in DIGLYME (diethylene glycol dimethyl ether) is used as the electrolyte, and a sodium ion battery is assembled under an argon atmosphere.

[0051] Figure 5 The resin-based hard carbon material obtained in Comparative Example 1 without any modification of aromatic ring side chain groups is applied to the first cycle charge and discharge curve of a sodium ion battery. It can be seen that the sodium ion battery hard carbon negative electrode material has a first coulombic efficiency of 83.7% and a reversible specific capacity of 302.7 mAh / g.

[0052] Figure 6 The rate performance curve of the resin-based hard carbon material obtained in Comparative Example 1 without any modification of aromatic ring side chain groups when applied to sodium ion batteries shows that the reversible specific capacity of the sodium ion battery hard carbon negative electrode material at a current density of 5C (1C = 30mA / g) is only 79.5mAh / g.

[0053] Figure 7 This is the cycle stability curve of the resin-based hard carbon material obtained in Comparative Example 1 without any modification of aromatic ring side chain groups and applied to sodium ion batteries. It can be seen that the sodium ion battery hard carbon negative electrode material can be stably cycled for 1000 cycles at a current density of 2C, and the cycle capacity retention rate decays to 76.2%.

[0054] Example 2

[0055] 1) 2 g of resorcinol and 9 mL of anhydrous ethanol were added to a three-necked flask. After the resorcinol was completely dissolved, 4.1 g of p-phenylbenzaldehyde was added. After stirring for 10 minutes, 10 mL of a 1 mol / L aqueous sodium hydroxide solution was added. The mixture was heated at 60°C under a reflux apparatus for 20 hours and finally polycondensed until it gelled.

[0056] 2) The gel product obtained in step 1) was air-dried at room temperature, then transferred to a muffle furnace and cured at 200° C. for 2 h. After cooling to room temperature, the powder was ground into powder, washed with deionized water, and filtered. The powder was then dried in a forced air oven at 80° C. for 24 h to obtain a phenolic resin containing a biphenyl group having a steric hindrance effect.

[0057] 3) The phenolic resin obtained in step 2) is carbonized at 1400° C. for 1 hour under an argon inert atmosphere to obtain the resin-based hard carbon material based on the steric hindrance effect of the biphenyl group.

[0058] 4) The resin-based hard carbon material obtained in step 3) is used as the negative electrode, metallic sodium is used as the counter electrode, glass fiber is used as the separator, and 1MNaPF6 in DIGLYME (diethylene glycol dimethyl ether) is used as the electrolyte, and a sodium ion battery is assembled under an argon atmosphere.

[0059] Example 3

[0060] 1) 2 g of resorcinol and 9 mL of anhydrous ethanol were added to a three-necked flask. After the resorcinol was completely dissolved, 2.2 mL of 5-methylfurfural was added. After stirring for 10 minutes, 10 mL of a 1 mol / L aqueous sodium hydroxide solution was added. The mixture was heated at 60°C under a reflux system for 20 hours and finally polycondensed until gelation occurred.

[0061] 2) The gel product obtained in step 1) was air-dried at room temperature, then transferred to a muffle furnace and cured at 200° C. for 2 h. After cooling to room temperature, the powder was ground into powder, washed with deionized water, and filtered. The powder was then dried in a forced air oven at 80° C. for 24 h to obtain a phenolic resin containing a steric hindrance effect of a 5-methylfuran group.

[0062] 3) The phenolic resin obtained in step 2) is carbonized at 1400° C. for 1 hour under an argon inert atmosphere to obtain the resin-based hard carbon material based on the steric hindrance effect of the 5-methylfuran group.

[0063] 4) The resin-based hard carbon material obtained in step 3) is used as the negative electrode, metallic sodium is used as the counter electrode, glass fiber is used as the separator, and 1MNaPF6 in DIGLYME (diethylene glycol dimethyl ether) is used as the electrolyte, and a sodium ion battery is assembled under an argon atmosphere.

[0064] Table 1: Sodium ion battery test results of Example 13 and Comparative Example 1

[0065] Group First cycle reversible capacity First coulombic efficiency Rate performance (5C) Example 1 340.3mAh / g 88.5％ 210.7mAh / g Comparative Example 1 302.7mAh / g 83.7％ 79.5mAh / g Example 2 334.3mAh / g 88.1％ 258.9mAh / g Example 3 321.8mAh / g 88.3％ 205.4mAh / g

[0066] (Note: 5C = 1500mA / g)

[0067] As can be seen from Table 1, the first-cycle reversible capacity and first coulombic efficiency of Examples 1 to 3 are significantly better than those of Comparative Example 1, indicating that the steric hindrance effect of the aromatic group can bring a larger spatial free volume and molecular chain rigidity to the resin, thereby effectively regulating the microstructure of the resin-based hard carbon during the pyrolysis carbonization process, forming a more compact short-range graphitized carbon layer and more abundant closed pores, thereby improving the reversible sodium storage capacity of the hard carbon. In addition, the rate performance of Examples 1 to 3 still maintains a capacity of more than 200mAh / g at a current density of 5C, which is better than that of Comparative Example 1. This shows that the steric hindrance effect of the aromatic group can reduce the number of pyrolysis rearrangements during the resin pyrolysis process, forming a more short-range disordered carbon layer structure, which is conducive to the rapid diffusion of sodium ions, thereby improving the rate performance of the battery. In addition, Example 2 has the best rate performance (258.9 mAh / g), indicating that a larger number of benzene rings in biphenyl can bring higher thermal stability, effectively inhibit the excessive graphitization of the carbon layer and form a larger graphite interlayer spacing, confirming that reasonable aromatic groups have a positive effect on the construction of high-rate resin-based hard carbon negative electrodes.

[0068] Example 4

[0069] 1) 1.71 g of phenol and 9 mL of anhydrous ethanol were added to a three-necked flask. After the resorcinol was completely dissolved, 2.8 mL of cinnamaldehyde was added. After stirring for 10 minutes, 10 mL of a 1 mol / L sodium hydroxide aqueous solution was added. The mixture was heated at 60° C. under a reflux apparatus for 10 hours and finally polycondensed until gelation occurred. The molecular structure of the gel product of step 1) is shown below:

[0070]

[0071] Wherein, R is a vinylphenyl side chain group.

[0072] 2) The gel product obtained in step 1) was air-dried at room temperature, then transferred to a muffle furnace and cured at 200° C. for 2 h. After cooling to room temperature, the powder was ground into powder, washed with deionized water, and filtered. The powder was then dried in a forced air oven at 80° C. for 24 h to obtain a phenolic resin containing vinylphenyl side chain groups.

[0073] 3) The phenolic resin obtained in step 2) is carbonized at 1400° C. for 1 hour under an argon inert atmosphere to obtain the resin-based hard carbon material based on the steric hindrance effect of the vinylphenyl group.

[0074] 4) The resin-based hard carbon material obtained in step 3) is used as the negative electrode, metallic sodium is used as the counter electrode, glass fiber is used as the separator, and 1MNaPF6 in DIGLYME (diethylene glycol dimethyl ether) is used as the electrolyte, and a sodium ion battery is assembled under an argon atmosphere.

[0075] Example 5

[0076] 1) 2.29 g of phloroglucinol and 9 mL of anhydrous ethanol were added to a three-necked flask. After the resorcinol was completely dissolved, 2.8 mL of cinnamaldehyde was added. After stirring for 10 minutes, 10 mL of a 1 mol / L sodium hydroxide aqueous solution was added. The mixture was heated at 60° C. under a condensation reflux apparatus for 25 hours, and finally polycondensed until gelation occurred. The molecular structure of the gel product of step 1) is shown below:

[0077]

[0078] Wherein, R is a vinylphenyl side chain group.

[0079] 2) The gel product obtained in step 1) was air-dried at room temperature, then transferred to a muffle furnace and cured at 200° C. for 2 h. After cooling to room temperature, the powder was ground into powder, washed with deionized water, and filtered. The powder was then dried in a forced air oven at 80° C. for 24 h to obtain a phenolic resin containing vinylphenyl side chain groups.

[0080] 3) The phenolic resin obtained in step 2) is carbonized at 1200° C. for 3 h under an argon inert atmosphere to obtain the resin-based hard carbon material based on the steric hindrance effect of the vinylphenyl group.

[0081] 4) The resin-based hard carbon material obtained in step 3) is used as the negative electrode, metallic sodium is used as the counter electrode, glass fiber is used as the separator, and 1MNaPF6 in DIGLYME (diethylene glycol dimethyl ether) is used as the electrolyte, and a sodium ion battery is assembled under an argon atmosphere.

[0082] Example 6

[0083] 1) 2 g of resorcinol and 9 mL of anhydrous ethanol were added to a three-necked flask. After the resorcinol was completely dissolved, 2.4 g of benzaldehyde was added. After stirring for 10 minutes, 10 mL of a 1 mol / L aqueous sodium hydroxide solution was added. The mixture was heated at 60°C under a reflux apparatus for 20 hours and finally polycondensed until it gelled.

[0084] 2) The gel product obtained in step 1) was air-dried at room temperature, then transferred to a muffle furnace and cured at 200° C. for 2 h. After cooling to room temperature, the powder was ground into powder, washed with deionized water, and filtered. The powder was then dried in a forced air oven at 80° C. for 24 h to obtain a phenolic resin containing a steric hindrance effect of a benzyl group.

[0085] 3) The phenolic resin obtained in step 2) is carbonized at 1500° C. for 1 hour under an argon inert atmosphere to obtain the resin-based hard carbon material based on the steric hindrance effect of the biphenyl group.

[0086] 4) The resin-based hard carbon material obtained in step 3) is used as the negative electrode, metallic sodium is used as the counter electrode, glass fiber is used as the separator, and 1MNaPF6 in DIGLYME (diethylene glycol dimethyl ether) is used as the electrolyte, and a sodium ion battery is assembled under an argon atmosphere.

[0087] The above embodiments are preferred embodiments of the present invention and are intended only to explain the present invention, not to limit the present invention. Any other changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principles of the present invention shall be considered equivalent replacements and shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing resin-based hard carbon based on the steric hindrance effect of aromatic groups, characterized in that: The preparation method comprises the following steps: An aldehyde compound containing an aromatic group, a phenolic compound, ethanol and a sodium hydroxide solution are stirred and mixed, heated and polycondensed in a condensation reflux device until gelation occurs, and air-dried at room temperature to obtain a phenolic resin containing a steric hindrance effect of an aromatic ring group; The phenolic resin is transferred to a muffle furnace for post-curing, and then washed with deionized water, filtered, and dried; The cured phenolic resin is subjected to high-temperature pyrolysis and carbonization under the protection of an inert atmosphere to obtain the resin-based hard carbon; The phenolic resin containing the steric hindrance effect of the aromatic group has a structure shown in one of formulas (1) to (3): In formulas (1) to (3), R represents a side chain group containing an aromatic ring; The aromatic ring side chain group R is one of the following formulas (1) to (4):

2. The method for preparing resin-based hard carbon based on the steric hindrance effect of aromatic groups according to claim 1, characterized in that: The R is an aromatic ring side chain group with a thermal decomposition temperature of 400 to 600°C.

3. The method for preparing resin-based hard carbon based on the steric hindrance effect of aromatic groups according to claim 1, characterized in that: The molar ratio of the aldehyde compound, the phenolic compound and the sodium hydroxide is 1.25:1:0.

55.

4. The method for preparing resin-based hard carbon based on the steric hindrance effect of aromatic groups according to claim 1, characterized in that: The heating polycondensation temperature is 60° C., and the heating polycondensation time is 10-25 hours.

5. The method for preparing resin-based hard carbon based on the steric hindrance effect of aromatic groups according to claim 1, characterized in that: The post-curing temperature is 200° C. and the post-curing time is 2 hours.

6. The method for preparing resin-based hard carbon based on the steric hindrance effect of aromatic groups according to claim 1, characterized in that: The temperature of the high-temperature pyrolysis carbonization is 1200-1500° C., and the time is 1-3 hours.

7. Resin-based hard carbon based on the steric hindrance effect of aromatic groups, obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the resin-based hard carbon based on the steric hindrance effect of aromatic groups obtained by the preparation method according to any one of claims 1 to 6, characterized in that: The resin-based hard carbon based on the steric hindrance effect of aromatic groups is used as the negative electrode material of sodium ion batteries.

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