Hard carbon material with low cost and high rate capability as well as preparation method and application of hard carbon material

Abstract

The invention belongs to the technical field of sodium ion battery negative electrodes, and particularly relates to a low-cost high-rate-performance hard carbon material as well as a preparation method and application thereof. The specific preparation process comprises the following steps: firstly, carrying out low-temperature pre-oxidation treatment on asphalt, then uniformly mixing the pre-oxidized asphalt with biomass, tabletting according to different mass proportions, and carrying out low-temperature-high-temperature calcination in an inert atmosphere to finally obtain the hard carbon material with low cost and high rate performance. According to the invention, the biomass is added into the asphalt precursor to improve the rate capability and low-temperature performance of the sodium-ion battery hard carbon material for the first time, and the practical process of applying the hard carbon to the sodium-ion battery on a large scale is further promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion battery negative electrodes, and in particular relates to a low-cost and high-rate performance hard carbon material and a preparation method and application thereof. Background Art

[0002] With the explosive growth of energy storage application demand, people have concerns about the economic sustainability of lithium-ion batteries due to the global shortage of lithium resources. In recent years, sodium-ion batteries have broad application prospects in large-scale energy storage due to their low cost, abundant resources and good low-temperature performance.

[0003] However, the lack of high-performance negative electrode materials has severely restricted the further development of sodium-ion batteries. At present, low-cost and high-capacity hard carbon is the preferred negative electrode material for large-scale application in sodium-ion batteries. Hard carbon materials have a wide interlayer spacing, which is conducive to Na + However, there are still some key issues to be solved in the application of hard carbon in sodium ion batteries. On the one hand, due to the large specific surface area of ​​hard carbon, it undergoes an irreversible reaction with the electrolyte during the first discharge process, consuming part of the Na + , which leads to a low first-cycle Coulomb efficiency (ICE) of hard carbon. On the other hand, the rapid sodium storage of hard carbon is concentrated in the slope region, and the sodium storage kinetics in the platform region is poor. + The diffusion energy barrier is high, which leads to poor rate performance and cycle stability. The low ICE and poor rate performance of hard carbon hinder the further commercial application of hard carbon materials. Therefore, how to improve the ICE and rate performance of hard carbon materials has become a key difficulty in the commercial application of hard carbon materials in sodium-ion batteries. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art, provide a low-cost and high-rate performance hard carbon material and its preparation method and application, and solve the problems existing in the hard carbon negative electrode of sodium ion battery in the above technical background.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a low-cost and high-rate performance hard carbon material, comprising the following steps:

[0007] Step 1: calcining the asphalt to obtain pre-oxidized asphalt;

[0008] Step 2: uniformly mixing the pre-oxidized asphalt and the biomass to obtain a precursor;

[0009] Step 3: Press the precursor into tablets and then calcine them to obtain a hard carbon material.

[0010] Furthermore, in step 1, the calcination temperature is 200-500°C, the time is 1-10h, and the heating rate is 1-5°C / min.

[0011] Furthermore, in step 2, the biomass is at least one of starch, glycine, tryptophan, sodium alginate, guar gum, cellulose, lignin, and maleic anhydride.

[0012] Furthermore, in step 2, the mass ratio of pre-oxidized asphalt to biomass is 5:(5-1).

[0013] Furthermore, the calcination in step 2 is low-temperature-high-temperature calcination, the temperature of the low-temperature calcination is 400-800°C, the time is 1-10h, and the heating rate is 1-5°C / min; the temperature of the high-temperature calcination is 800-1400°C, the time is 2-24h, and the heating rate is 1-5°C / min.

[0014] In a second aspect, the present invention provides a hard carbon material prepared by the preparation method described in the first aspect.

[0015] In a third aspect, the present invention provides an application of the hard carbon material described in the second aspect in the field of sodium ion batteries.

[0016] In a fourth aspect, the present invention provides a negative electrode material for a sodium ion battery, comprising the hard carbon material described in the third aspect.

[0017] In a fifth aspect, the present invention provides a sodium ion battery comprising the sodium ion battery negative electrode material described in the fourth aspect.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The hard carbon material prepared by asphalt in the present invention has better consistency and reduces the production cost of hard carbon.

[0020] (2) The hard carbon material prepared by the present invention has good electronic conductivity, which effectively accelerates electron transfer and thus improves the rate performance of the hard carbon material in sodium ion batteries.

[0021] (3) The hard carbon prepared by the present invention has a lower specific surface area, which effectively reduces the side reaction between the electrolyte and the hard carbon during the first discharge process and thus improves the ICE of the pitch-based hard carbon material.

[0022] (4) The present invention introduces other biomass carbon sources into the precursor to increase the interlayer spacing of the hard carbon and reduce the Na + diffusion energy barrier.

[0023] (5) The present invention can obtain a hard carbon material rich in "short-range few-layer" pseudo-graphite microcrystals through the above preparation method, which effectively shortens the Na + The diffusion path of Na + Diffusion rate, rate performance and low temperature performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the XRD pattern of the hard carbon material prepared in Example 1;

[0025] Figure 2 This is a SEM image of the hard carbon material prepared in Example 1;

[0026] Figure 3 This is a rate performance diagram of the hard carbon material prepared in Example 1. DETAILED DESCRIPTION

[0027] In order to facilitate understanding of the present invention, the present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0028] Example 1

[0029] Weigh 5g of asphalt and put it into a muffle furnace, heat it to 300℃ at 1℃ / min and calcine for 4h, cool it naturally to room temperature to obtain pre-oxidized asphalt, weigh 5g of pre-oxidized asphalt and 1g of starch, mix them, press them into sheets and put them into a tubular furnace, under the protection of argon atmosphere, heat it to 400℃ at 1℃ / min and calcine for 6h, cool it naturally to room temperature, heat it to 1000℃ at 2℃ / min and calcine for 12h, cool it naturally to room temperature to obtain a hard carbon material.

[0030] Figure 1 This is the XRD diagram of the hard carbon material prepared in Example 1. From the characteristic peaks, it can be seen that the material is a hard carbon material. Figure 2 This is the SEM image of the hard carbon material prepared in Example 1. It can be seen that the surface of the prepared material is smooth and defect-free, which is beneficial to reducing the specific surface area and improving the ICE of the hard carbon material.

[0031] Example 2

[0032] Weigh 5g of asphalt and put it into a muffle furnace, heat it to 500℃ at 5℃ / min and calcine it for 10h, cool it naturally to room temperature to obtain pre-oxidized asphalt, weigh 5g of pre-oxidized asphalt and 5g of guar gum, mix them, press them into sheets and put them into a tubular furnace, heat it to 800℃ at 5℃ / min under argon atmosphere and calcine it for 10h, cool it naturally to room temperature, heat it to 1400℃ at 5℃ / min and calcine it for 24h, cool it naturally to room temperature to obtain a hard carbon material.

[0033] Example 3

[0034] Weigh 5g of asphalt and put it into a muffle furnace, heat it to 200℃ at 3℃ / min and calcine for 1h, cool it naturally to room temperature to obtain pre-oxidized asphalt, weigh 5g of pre-oxidized asphalt and 3g of glycine, mix them, press them into tablets, and put them into a tubular furnace, under the protection of argon atmosphere, heat it to 500℃ at 3℃ / min and calcine for 1h, cool it naturally to room temperature, heat it to 800℃ at 3℃ / min and calcine for 2h, cool it naturally to room temperature to obtain a hard carbon material.

[0035] Example 4

[0036] Weigh 5g of asphalt and put it into a muffle furnace, heat it to 400℃ at 2℃ / min and calcine it for 7h, cool it naturally to room temperature to obtain pre-oxidized asphalt, weigh 5g of pre-oxidized asphalt and 2g of lignin, mix them, press them into sheets and put them into a tubular furnace, under the protection of argon atmosphere, heat it to 600℃ at 2℃ / min and calcine it for 7h, cool it naturally to room temperature, heat it to 1200℃ at 2℃ / min and calcine it for 6h, cool it naturally to room temperature to obtain a hard carbon material.

[0037] Example 5

[0038] Weigh 5g of asphalt and put it into a muffle furnace, heat it to 300℃ at 4℃ / min and calcine it for 5h, cool it naturally to room temperature to obtain pre-oxidized asphalt, weigh 5g of pre-oxidized asphalt and 4g of cellulose, mix them, press them into sheets and put them into a tubular furnace, under the protection of argon atmosphere, heat it to 700℃ at 4℃ / min and calcine it for 6h, cool it naturally to room temperature, heat it to 900℃ at 2℃ / min and calcine it for 4h, cool it naturally to room temperature to obtain a hard carbon material.

[0039] Comparative Example

[0040] Weigh 5g of asphalt and put it into a muffle furnace, heat it to 300℃ at 1℃ / min and calcine for 3h, cool it naturally to room temperature to obtain pre-oxidized asphalt, weigh 5g of pre-oxidized asphalt, press it into sheets and put it into a tubular furnace, under the protection of argon atmosphere, heat it to 500℃ at 1℃ / min and calcine for 6h, cool it naturally to room temperature, heat it to 1300℃ at 2℃ / min and calcine for 18h, cool it naturally to room temperature to obtain hard carbon material.

[0041] The hard carbon materials obtained in the above Examples 1-5 and the comparative example were prepared as negative electrodes for sodium ion batteries, assembled with sodium metal into batteries, and subjected to charge and discharge performance tests. The test results are shown in Tables 1-3, wherein the rate performance diagram of the hard carbon material prepared in Example 1 is shown in Figure 3 .

[0042] Table 1

[0043]

[0044] Table 2

[0045]

[0046]

[0047] Table 3

[0048]

[0049] It can be seen from the above table that the lateral comparison data of Example 1, Example 2, Example 3, Example 4 and Example 5 with the comparative example respectively prove that the electrochemical performance of the sodium ion battery hard carbon material of the mixed biomass precursor in the pre-oxidized asphalt precursor is better than that of the sodium ion battery hard carbon material of the unmixed biomass precursor.

[0050] The above description is only for better explaining the embodiments of the present invention, and is not intended to limit the present invention. Any modification or equivalent substitution that does not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing a low-cost and high-rate performance hard carbon material, characterized in that: The steps include: Step 1: calcining the asphalt to obtain pre-oxidized asphalt; Step 2: uniformly mixing the pre-oxidized asphalt and the biomass to obtain a precursor; Step 3: Press the precursor into tablets and then calcine them to obtain a hard carbon material.

2. The method for preparing a low-cost and high-rate performance hard carbon material according to claim 1, characterized in that: In the step 1, the calcination temperature is 200-500° C., the time is 1-10 h, and the heating rate is 1-5° C. / min.

3. The method for preparing a low-cost and high-rate performance hard carbon material according to claim 1, characterized in that: In step 2, the biomass is at least one of starch, glycine, tryptophan, sodium alginate, guar gum, cellulose, lignin, and maleic anhydride.

4. The method for preparing a low-cost and high-rate performance hard carbon material according to claim 1, characterized in that: In step 2, the mass ratio of pre-oxidized asphalt to biomass is 5:(5-1).

5. The method for preparing a low-cost and high-rate performance hard carbon material according to claim 1, characterized in that: The calcination in step 2 is low-temperature-high-temperature calcination, the temperature of the low-temperature calcination is 400-800°C, the time is 1-10h, and the heating rate is 1-5°C / min; the temperature of the high-temperature calcination is 800-1400°C, the time is 2-24h, and the heating rate is 1-5°C / min.

6. A hard carbon material, characterized in that The preparation method is described in any one of claims 1 to 6.

7. Use of the hard carbon material according to claim 6 in the field of sodium ion batteries.

8. A sodium ion battery negative electrode material, characterized in that: Comprising the hard carbon material as claimed in claim 6.

9. A sodium ion battery, characterized in that: Contains the sodium ion battery negative electrode material according to claim 8.

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