A sulfur-doped composite hard carbon material, a preparation method and application thereof

Abstract

The application discloses a sulfur-doped composite hard carbon material and a preparation method and application thereof. A sulfonated resin is used as a carbon source and a sulfur source, nonmetallic sulfur atoms with an atomic radius larger than that of carbon are in-situ doped, the carbon layer spacing of the hard carbon is increased, and the rate performance of the hard carbon is improved. The sulfonated resin is pre-coated and modified on the surface by using a cheap biomass carbon source, the specific surface area and defect sites of the hard carbon are reduced, the number of closed pores is increased, and the specific capacity and the first coulomb efficiency of the hard carbon are improved.

Description

TECHNICAL FIELD

[0001] The application relates to a sulfur-doped composite hard carbon material and a preparation method and application thereof, and belongs to the field of hard carbon materials. BACKGROUND

[0002] With the continuous exploitation and consumption of global fossil energy, fossil resources are becoming increasingly scarce, and environmental pollution and greenhouse effect are becoming increasingly serious. Therefore, clean energy such as solar energy, wind energy and tidal energy needs to be vigorously developed. However, due to factors such as weather, location and time, the large-scale application and popularization of these clean energies need to be matched with large-scale energy storage systems. Secondary batteries are a good choice for large-scale energy storage due to their high energy density and conversion efficiency. Lithium ion batteries have been widely used in the field of power batteries due to their high energy density and long cycle life. However, the limited lithium resources and the rising prices of raw materials have seriously limited the application of lithium ion batteries in the field of large-scale energy storage.

[0003] Compared with lithium ion batteries, sodium ion batteries (SIBs) have a broad application prospect in the field of large-scale energy storage due to their high resource abundance, low cost and high safety. Compared with lithium ions, sodium ions have a larger radius, so the traditional graphite negative electrode material (interlayer spacing 0.334 nm) and soft carbon negative electrode material (interlayer spacing <0.36 nm) have lower sodium storage capacity and lower first coulombic efficiency due to the smaller interlayer spacing, which limits their practicality. In contrast, hard carbon negative electrode materials have a larger interlayer spacing >0.38 nm, so they have a higher sodium storage capacity (300 mAh g-1), a lower sodium storage platform (~0.1 V) and good cycle stability, and are considered to be very promising commercial negative electrode materials for sodium ion batteries. However, the abundant defect sites on the hard carbon negative electrode will cause irreversible adsorption of sodium ions, resulting in a decrease in specific capacity and first coulombic efficiency. In addition, the carbon layer spacing of traditional hard carbon is still relatively small, resulting in poor rate performance. Therefore, how to reduce defects and increase the interlayer spacing is a key way to develop hard carbon negative electrode materials for sodium ion batteries with high specific capacity and good rate performance. SUMMARY

[0004] According to one aspect of the application, a preparation method of a sulfur-doped composite hard carbon material is provided. The sulfonated resin is used as a carbon source and a sulfur source, non-metallic sulfur atoms with a larger atomic radius than carbon are doped in situ, the carbon layer spacing of the hard carbon is increased, and the rate performance of the hard carbon is improved. The sulfonated resin is modified by a cheap biomass carbon source to reduce the specific surface area and defect sites of the hard carbon, improve the specific capacity and first coulombic efficiency of the hard carbon, and solve the problem of how to prepare a hard carbon negative electrode material for sodium ion batteries with few defects and large interlayer spacing.

[0005] The application adopts the following technical scheme:

[0006] A preparation method of a sulfur-doped composite hard carbon material, comprising the following steps:

[0007] S1: mixing a sulfonated resin and a solution containing a polyhydroxy compound to form a solid-liquid mixture;

[0008] S2: placing the solid-liquid mixture obtained in step S1 in a sealed container and heating to react to obtain a modified sulfonated resin;

[0009] S3: pyrolyzing and carbonizing the modified sulfonated resin obtained in step S2 to obtain the sulfur-doped composite hard carbon material.

[0010] Optionally, the polyhydroxy compound is selected from at least one of glucose, sucrose, glycerol, sorbitol, and ascorbic acid.

[0011] Optionally, the content of the polyhydroxy compound in the solution of the polyhydroxy compound is 5-60 wt%.

[0012] Optionally, the content of the polyhydroxy compound in the solution of the polyhydroxy compound is selected from any value of 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, or a range value between any two of them.

[0013] Optionally, the sulfonated resin is selected from at least one of sulfonated polystyrene resin, sulfonated phenol-formaldehyde resin, and sulfonated lignite resin.

[0014] Optionally, in step S1, the weight ratio of the polystyrene-based sulfonated resin to the solution of the polyhydroxy compound is 0.1-5:1.

[0015] Optionally, in step S1, the weight ratio of the polystyrene-based sulfonated resin to the solution of the polyhydroxy compound is selected from any value of 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, or a range value between any two of them.

[0016] Optionally, in step S2, the heating reaction conditions include that the reaction temperature is 80-250℃, and the reaction time is 0.5-24h.

[0017] Optionally, in step S2, the heating reaction temperature is selected from any value of 80℃, 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 230℃, 250℃, or a range value between any two of them.

[0018] Optionally, in step S2, the heating reaction time is selected from any value of 0.5h, 5h, 10h, 15h, 20h, 24h, or a range value between any two of them.

[0019] Optionally, in step S3, the cracking condition comprises: being carried out under a non-reactive gas atmosphere, the cracking temperature is 300-600℃, and the cracking time is 0.5-8h.

[0020] Optionally, in step S3, the cracking temperature is selected from any value in 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, or a range value between any two of them.

[0021] Optionally, in step S3, the carbonization condition comprises: being carried out under a non-reactive gas atmosphere, the carbonization temperature is 800-1600℃, and the carbonization time is 0.5-12h.

[0022] Optionally, the non-reactive gas atmosphere is selected from at least one of nitrogen, argon, and helium.

[0023] Optionally, in step S2, after heating reaction, it further comprises filtering and drying.

[0024] The drying condition comprises: the temperature is 100-250℃, and the time is 1-12h.

[0025] According to another aspect of the present application, there is provided a sulfur-doped composite hard carbon material prepared by the above preparation method, wherein the mass content of sulfur element in the sulfur-doped composite hard carbon material is 0.1-10%.

[0026] Optionally, the specific surface area of the sulfur-doped composite hard carbon material is 0.1-50m 2 / g.

[0027] Optionally, the carbon layer spacing of the sulfur-doped composite hard carbon material is 0.37-0.45nm.

[0028] According to another aspect of the present application, there is also provided a negative electrode material comprising the sulfur-doped composite hard carbon material of claim 8.

[0029] According to another aspect of the present application, there is also provided a sodium ion battery comprising the negative electrode material of claim 9.

[0030] The present application can produce the beneficial effects including:

[0031] The preparation method provided by the present application has simple preparation process, and the obtained composite hard carbon has small specific surface area, few defects, large carbon layer spacing, high specific capacity, high first coulomb efficiency, and high rate of the sodium ion battery prepared as a negative electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1Transmission electron microscope image of the composite hard carbon material obtained in Example 1.

[0033] Figure 2 Nitrogen physical adsorption curve of the composite hard carbon material obtained in Example 1. DETAILED DESCRIPTION

[0034] The present application will be described in detail below with reference to examples, but the present application is not limited to these examples.

[0035] The raw materials in the examples of the present application are all purchased through commercial channels unless otherwise specified.

[0036] Example 1

[0037] S1: 10 g of sulfonated polystyrene resin was dispersed in 50 g of a glucose solution with a mass fraction of 20% to form a solid-liquid mixture;

[0038] S2: The solid-liquid mixture was transferred into an autoclave, reacted at 180°C for 12 h, cooled to room temperature, and filtered to obtain a solid, which was dried at 120°C to obtain a modified resin;

[0039] S3: The modified resin was placed in a nitrogen atmosphere, heated to 400°C, and kept at this temperature for 2 h to obtain a low-temperature pyrolysis product;

[0040] S4: The low-temperature pyrolysis product was placed in a nitrogen atmosphere, heated to 1200°C, and kept at this temperature for 2 h to obtain a composite hard carbon material. The content of sulfur element in the obtained hard carbon material was 3.4%.

[0041] Figure 1 Transmission electron microscope image of the composite hard carbon material obtained in Example 1, with a carbon layer spacing of 0.39 nm.

[0042] Figure 2 Nitrogen physical adsorption curve of the composite hard carbon material obtained in Example 1, with a specific surface area of 26 m 2 / g.

[0043] Example 2

[0044] The same as Example 1, except that the concentration of the glucose solution in S1 was increased to 60%, and the rest was the same as Example 1.

[0045] The specific surface area of the composite hard carbon material obtained in Example 2 was 6 m 2 / g, the carbon layer spacing was 0.39 nm, and the content of sulfur element was 2.7%.

[0046] Example 3

[0047] The same as Example 1, except that the mass of the 20% by mass glucose solution in S1 is replaced with 5 g, and the rest is the same as Example 1.

[0048] The specific surface area of the composite hard carbon material obtained in Example 3 is 48 m 2 / g, the carbon layer spacing is 0.37 nm, and the sulfur element content is 3.7%.

[0049] Examples 4 to 7

[0050] The same as Example 1, except that the glucose solution in S1 is replaced with sucrose, glycerol, sorbitol, and ascorbic acid in turn, and the rest is the same as Example 1.

[0051] The specific surface area of the composite hard carbon material obtained in Examples 4 to 7 is 24 m 2 / g, 41 m 2 / g, 37 m 2 / g, and 31 m 2 / g, respectively, the carbon layer spacing is 0.38 nm, 0.37 nm, 0.39 nm, 0.39 nm, respectively, and the sulfur element content is 3.64%, 3.21%, 3.68%, 3.79%, respectively.

[0052] Examples 8 to 9

[0053] The same as Example 1, except that the reaction temperature in S2 is replaced with 80°C and 250°C in turn, and the rest is the same as Example 1.

[0054] The specific surface area of the composite hard carbon material obtained in Examples 8 to 9 is 39 m 2 / g and 13 m 2 / g, respectively, the carbon layer spacing is 0.37 nm and 0.43 nm, respectively, and the sulfur element content is 2.9% and 4.67%, respectively.

[0055] Example 10

[0056] The same as Example 1, except that the reaction time in S2 is replaced with 24 h, and the rest is the same as Example 1.

[0057] The specific surface area of the composite hard carbon material obtained in Example 10 is 11 m 2 / g, the carbon layer spacing is 0.45 nm, and the sulfur element content is 6.77%.

[0058] Example 11

[0059] The same as Example 1, except that the cracking temperature in S3 is replaced with 600°C, and the rest is the same as Example 1.

[0060] The specific surface area of the composite hard carbon material obtained in Example 11 was 34 m 2 / g, the carbon layer spacing was 0.38 nm, and the sulfur element content was 3.7%.

[0061] Example 12

[0062] Example 1 was substantially the same, except that the carbonization temperature in S3 was replaced with 1500°C, and the rest was exactly the same as Example 1.

[0063] The specific surface area of the composite hard carbon material obtained in Example 12 was 0.5 m 2 / g, the carbon layer spacing was 0.39 nm, and the sulfur element content was 4.3%.

[0064] Example 13

[0065] Example 1 was substantially the same, except that the sulfonated polystyrene resin in S1 was replaced with a sulfonated phenol-aldehyde resin, and the rest was exactly the same as Example 1.

[0066] The specific surface area of the composite hard carbon material obtained in Example 13 was 7.5 m 2 / g, the carbon layer spacing was 0.383 nm, and the sulfur element content was 6.9%.

[0067] Comparative Example 1

[0068] Example 1 was substantially the same, except that the reaction stage in a high-pressure autoclave in S2 was omitted, and the rest was exactly the same as Example 1.

[0069] The specific surface area of the composite hard carbon material obtained in Comparative Example 1 was 68 m 2 / g, the carbon layer spacing was 0.37 nm, and the sulfur element content was 0.7%.

[0070] Comparative Example 2

[0071] Example 1 was substantially the same, except that the glucose solution in S1 was replaced with deionized water, and the rest was exactly the same as Example 1.

[0072] The specific surface area of the composite hard carbon material obtained in Comparative Example 2 was 493 m 2 / g, the carbon layer spacing was 0.35 nm, and the sulfur element content was 0.05%.

[0073] Comparative Example 3

[0074] Example 1 was substantially the same, except that the cracking temperature in S3 was replaced with 250°C, and the rest was exactly the same as Example 1.

[0075] The specific surface area of the composite hard carbon material obtained in Comparative Example 3 was 137 m 2 / g, the carbon layer spacing is 0.363 nm, and the sulfur element content is 2.1%.

[0076] Comparative Example 4

[0077] The same as Example 1, except that the carbonization temperature in S3 is replaced by 700℃, and the rest is the same as Example 1.

[0078] The specific surface area of the composite hard carbon material obtained in Comparative Example 4 is 211 m 2 / g, the carbon layer spacing is 0.372 nm, and the sulfur element content is 11.8%.

[0079] Performance test experiment of sodium battery negative electrode of Example 13

[0080] The composite hard carbon, conductive carbon black and sodium carboxymethyl cellulose prepared in the above examples and comparative examples are mixed in deionized water at a weight ratio of 80:10:10, ground into a paste, coated on a copper foil current collector, then dried at 80℃ for 12h, and then cut into a diameter of 12mm by a film cutting machine, weighed, and the mass of the hard carbon material (active material) was calculated. Then, in an argon glove box, a 2032 button half-cell was assembled with a metal sodium sheet as the positive electrode, glass fiber as the separator, and 1mol / L NaPF6 / DEC:EC solution as the electrolyte. The sodium ion half-cell was tested for charge and discharge under constant current charge and discharge mode, with a voltage range of 1.0-4.2V, and the sodium battery charge and discharge performance of the hard carbon material was tested under different current densities (i.e. rate). The results are shown in Table 1.

[0081] Table 1: Sodium battery performance test results of hard carbon obtained in some examples and comparative examples.

[0082]

[0083] As can be seen from Table 1, the sulfur-doped composite hard carbon material prepared by the present application has the advantages of high specific capacity and good rate performance.

[0084] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments, and all belong to the scope of the technical solution.

Claims

1. A method for preparing a sulfur-doped composite hard carbon material, characterized by, The method comprises the following steps: S1: mixing a sulfonated resin and a solution containing a polyhydroxy compound to form a solid-liquid mixture; S2: placing the solid-liquid mixture obtained in step S1 in a sealed container and heating to react to obtain a modified sulfonated resin; S3: pyrolyzing and carbonizing the modified sulfonated resin obtained in step S2 to obtain the sulfur-doped composite hard carbon material.

2. The production method according to claim 1, characterized by, In step S1, the polyhydroxy compound is at least one selected from glucose, sucrose, glycerol, sorbitol, and ascorbic acid.

3. The preparation method according to claim 1, characterized in that, In step S1, the content of the polyhydroxy compound in the solution of the polyhydroxy compound is 5-60 wt%.

4. The method of claim 1, wherein, In step S1, the sulfonated resin is at least one selected from sulfonated polystyrene resin, sulfonated phenol-formaldehyde resin, and sulfonated lignite resin.

5. The preparation method according to claim 4, characterized in that, In step S1, the weight ratio of the polystyrene-based sulfonated resin to the solution of the polyhydroxy compound is 0.1-5:

1.

6. The method of claim 1, wherein, In step S2, the heating reaction conditions include a reaction temperature of 80-250°C and a reaction time of 0.5-24 h.

7. The preparation method according to claim 1, characterized in that, In step S3, the pyrolysis conditions include being performed in a non-reactive gas atmosphere, a pyrolysis temperature of 300-600°C, and a pyrolysis time of 0.5-8 h.

8. The method of claim 1, wherein, In step S3, the carbonization conditions include being performed in a non-reactive gas atmosphere, a carbonization temperature of 800-1600°C, and a carbonization time of 0.5-12 h.

9. The method of claim 1, wherein, In step S2, after the heating reaction, further comprising filtering and drying; The drying conditions include a temperature of 100-250°C and a time of 1-12 h.

10. The sulfur-doped composite hard carbon material prepared according to the method of any one of claims 1 to 9, characterized in that, In the sulfur-doped composite hard carbon material, the mass content of sulfur is 0.1-10%.

11. The sulfur-doped composite hard carbon material prepared according to the method of any one of claims 1 to 9, characterized in that, The specific surface area of the sulfur-doped composite hard carbon material is 0.1-50 m 2 / g.

12. The sulfur-doped composite hard carbon material prepared according to the method of any one of claims 1 to 9, characterized in that, The interlayer spacing of the carbon layer of the sulfur-doped composite hard carbon material is 0.37-0.45 nm.

13. A negative electrode material, characterized by, The sulfur-doped composite hard carbon material of claim 10.

14. A sodium-ion battery, characterized in that, The negative electrode material of claim 13.

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