Asphalt-based hard carbon material for sodium ion battery and preparation method of asphalt-based hard carbon material

Abstract

The invention belongs to the technical field of sodium ion battery negative electrode materials, and discloses an asphalt-based hard carbon material for a sodium ion battery and a preparation method of the asphalt-based hard carbon material. The 3, 4, 9, 10-perylenetetracarboxylic dianhydride is adopted as the cross-linking agent, the doping amount of the 3, 4, 9, 10-perylenetetracarboxylic dianhydride is only 10-30% of the mass of the asphalt, and the reversible sodium storage capacity of the asphalt can be remarkably improved under the condition limited by the invention. In an oxygen atmosphere, an anhydride group of 3, 4, 9, 10-perylenetetracarboxylic dianhydride and an oxygen-containing functional group in asphalt are subjected to a cross-linking reaction, and a formed cross-linking structure effectively inhibits melting rearrangement in an asphalt carbonization process, so that the electrochemical performance of the sodium-ion battery hard carbon negative electrode material is remarkably improved. According to the prepared asphalt-based hard carbon negative electrode material, 1 mol / L NaPF6-EC / DEC is used as an electrolyte, and under the current density of 20 mA / g, the initial coulombic efficiency reaches 75.64%, and the reversible capacity is 319.76 mAh / g; and under the current density of 200mA / g, the reversible capacity can still reach 189.14 mAh / g.

Description

Technical Field

[0001] The present invention belongs to the technical field of anode materials for sodium-ion batteries, and relates to a pitch-based hard carbon material for sodium-ion batteries and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in the field of renewable energy storage due to their advantages such as high energy density, long cycle life, and low self-discharge rate. However, the uneven global distribution and limited reserves of lithium resources have led to high costs for the large-scale application of lithium-ion batteries. Therefore, developing low-cost and sustainable alternative energy storage technologies has become an urgent need in the current energy storage field.

[0003] Sodium and lithium belong to the same main group. Sodium-ion batteries have lower costs, are more environmentally friendly, and have better safety, and are expected to achieve large-scale commercial development. However, the insertion / extraction kinetics of sodium ions is weak, which has become one of the main bottlenecks restricting its commercial development. Therefore, developing high-performance and low-cost anode materials is a key link in promoting the commercial application of sodium-ion batteries. Among many anode materials, pitch-based hard carbon materials show significant commercial potential due to their wide raw material sources and low costs. However, direct carbonization of pitch will cause melting, resulting in rearrangement of carbon layers, thus forming a soft carbon structure with closely arranged carbon layers and a low sodium storage capacity.

[0004] At present, it is usually adopted to pre-oxidize asphalt by introducing a certain flow rate of oxygen to inhibit its melting during the carbonization process. Although this method is simple to operate, the effect of oxidative crosslinking by this method is not ideal and it is difficult to meet the preparation requirements of high-performance hard carbon materials. The patent CN118062826 A, a high-capacity asphalt-based hard carbon material, its preparation method and its application, disclosed by Wuzhou Tongchuang New Energy Materials Co., Ltd. Air oxidizes asphalt, and the oxidized asphalt is crosslinked with a mercapto crosslinking agent and an organic sodium salt, and phosphine gas is introduced for heat treatment to obtain a hard carbon material. This process is relatively complex, requires the addition of a hydroxyl crosslinking agent, an organic sodium salt and phosphine gas, has high energy consumption and high cost, and phosphine gas has high danger. The patent CN 116023966 A, a method for rapid thermosetting transformation of asphalt, disclosed by Beijing Research Institute Co., Ltd., Ansteel Group. The patent is to mix powder asphalt with hydrogen peroxide and a metal-based catalyst and then carry out curing treatment in an oxygen atmosphere. The addition of the metal catalyst in this process results in high production cost. It is not suitable for large-scale production. As the negative electrode material of a sodium-ion battery, the reversible sodium storage capacity is relatively low, only up to 248 mAh / g at most. The performance is average. The patent CN116354335 A, a preparation method and application of asphalt-based hard carbon nanosheets, disclosed by the Institute of Coal Chemistry, Chinese Academy of Sciences. The patent is to fully stir coal tar pitch powder, dichloroethane solution, aluminum chloride and cyanuric chloride and carry out the reaction in a hydrothermal reaction kettle. This technology requires the addition of a variety of raw materials, hydrothermal reaction, which is dangerous and has high energy consumption. The added cyanuric chloride has a pungent smell, is unstable in the air, has volatility and irritation, and is highly toxic. Subsequently, potassium hydroxide needs to be added for activation. The process is cumbersome and the process cost is high, and the production process is not environmentally friendly. The patent CN117550585 A, a preparation method and application of a coal tar pitch-based hard carbon material, disclosed by Beijing University of Chemical Technology. The patent mixes an acid anhydride substance rich in halogen atoms such as Br, F, Cl, I with coal tar pitch evenly, and obtains a hard carbon negative electrode material through dehydrogenation and crosslinking driven by a high-temperature thermal field. The acid anhydride substance tetrabromophthalic anhydride used in this patent is toxic, and the amount of the added acid anhydride substance is relatively large, at least 50% of the mass of the asphalt needs to be added. The electrolyte used for evaluating its sodium storage performance when assembling a half-cell is an ether-based electrolyte, which is not suitable for actual production applications, has high process cost, and the production process is not environmentally friendly. The patent CN119059512 A, a gradient-structured coal-based hard carbon and its preparation method and application, disclosed by China University of Mining and Technology. The patent oxidatively crosslinks the deashed coal-based precursor in a wetting environment with less solvent, and then carries out gradient reduction treatment in a reducing atmosphere to achieve gradient reduction from the particle surface to the inside. Finally, it is carbonized to prepare a coal-based hard carbon material with an increasing degree of amorphousness gradient from the surface to the inside.The precursor used in this patent is lignite, which is treated by a hydrothermal method. Hazardous gases such as hydrogen or methane are also required, and pickling treatment is also needed. The process flow has great risks and is not suitable for large-scale industrial production. Moreover, its reversible sodium storage capacity is only 303.3 mAh / g.

[0005] Therefore, it is urgent to develop a more efficient cross-linking method to further improve the sodium storage performance of pitch-based hard carbon materials and promote the commercialization process of sodium-ion batteries. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a pitch-based hard carbon material for sodium-ion batteries and a preparation method thereof. By introducing highly active and non-toxic anhydride organic compounds and defining the cross-linking and carbonization processes, the reversible specific capacity and sodium storage performance of the material are significantly improved.

[0007] The above object of the present invention is achieved by the following technical solutions:

[0008] A preparation method of a pitch-based hard carbon material for sodium-ion batteries includes the following steps:

[0009] a. Solid-phase mixing of pitch and anhydride organic compounds to obtain a solid mixture;

[0010] b. Cross-linking the solid mixture obtained in step a in an oxygen atmosphere to obtain an intermediate product

[0011] c. Under an inert atmosphere, sequentially performing low-temperature pre-carbonization and high-temperature carbonization on the intermediate product obtained in step b to obtain the pitch-based hard carbon material.

[0012] Further, in step a, the softening point of the pitch is not lower than 200 °C, including one or more of petroleum pitch, coal tar pitch, biomass pitch, or coal liquefaction residue pitch.

[0013] Further, in step a, the anhydride organic compounds are one or more of phthalic anhydride, benzoic anhydride, pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, and 3,4,9,10-perylenetetracarboxylic dianhydride.

[0014] Further, in step a, the mass ratio of pitch to anhydride organic compounds is 1:50 to 100:1. Preferably, in step a, the mass ratio of pitch to anhydride organic compounds is 10:3 to 10:1.

[0015] Further, in step b, the cross-linking temperature is 300 - 350 °C, and the duration is 2 - 14 h.

[0016] Further, in step c, the low-temperature pre-carbonization conditions are as follows: heating up to 400 - 800 °C at a heating rate of 1 - 10 °C / min and holding for 1 - 2 hours.

[0017] Further, in step c, the high-temperature carbonization conditions are as follows: heating up to 1000 - 1600 °C at a heating rate of 1 - 10 °C / min and holding for 1 - 3 h.

[0018] The present invention also claims the application of the pitch-based hard carbon material prepared by the above preparation method in the preparation of the negative electrode of a sodium-ion battery.

[0019] The present invention also claims the application of the pitch-based hard carbon material prepared by the above preparation method in the preparation of the negative electrode of a sodium-ion battery.

[0020] The present invention also claims the application of the pitch-based hard carbon material prepared by the above preparation method in the preparation of a sodium-ion battery.

[0021] The present invention also claims the application of the sodium-ion battery prepared by using the pitch-based hard carbon material of the present invention in power supply for the manufacture of electric vehicles, mobile phones, laptop computers, electronic products, and mobile energy storage devices.

[0022] The beneficial effects of the present invention compared with the prior art are as follows:

[0023] The present invention provides a pitch-based hard carbon material for a sodium-ion battery and a preparation method thereof. The preparation method has a simple process, easy-to-control reaction conditions, and has the advantages of low cost and high efficiency, and is suitable for large-scale industrial application.

[0024] The pitch-based hard carbon material prepared by the method provided by the present invention has excellent sodium storage performance, providing a new technical route for the development of negative electrode materials for sodium-ion batteries. Specifically, the present invention uses 3,4,9,10-perylene tetracarboxylic dianhydride as a cross-linking agent, and its incorporation amount is only 10% - 30% of the mass of the pitch. Under the conditions defined by the present invention, it can significantly improve the reversible sodium storage capacity of the pitch. The cross-linking process adopts a one-step cross-linking method and is carried out in an oxygen atmosphere, with a simple and environmentally friendly process. In an oxygen atmosphere, the anhydride groups of 3,4,9,10-perylene tetracarboxylic dianhydride react with the oxygen-containing functional groups in the pitch to form a cross-linked structure, which effectively inhibits the melting rearrangement during the carbonization of the pitch, affects the interlayer spacing, specific surface area, pore structure, and graphitization degree of the pitch-based hard carbon, thereby significantly improving the electrochemical performance of the hard carbon negative electrode material for sodium-ion batteries. The prepared pitch-based hard carbon negative electrode material has a first Coulomb efficiency of 75.64% and a reversible capacity of 319.76 mAh / g at a current density of 20 mA / g with 1 mol / L NaPF6-EC / DEC as the electrolyte; at a current density of 200 mA / g, the reversible capacity can still reach 189.14 mAh / g.

[0025] The present invention has the advantage of low cost and can realize large-scale production of high-performance asphalt-based hard carbon materials. When applied to the negative electrode of sodium ion batteries, it exhibits excellent sodium storage performance and high specific capacity, providing important material support for the commercial application of sodium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a graph showing the first charge and discharge curves of the asphalt-based hard carbon material for sodium ion battery prepared in Example 1, Example 2, Example 3 and Comparative Example 1 of the present invention at 0.1C.

[0027] Figure 2 This is the XRD spectrum of the asphalt-based hard carbon material for sodium ion battery prepared in Example 1, Example 2, Example 3 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0028] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0029] The present invention limits the optimal anhydride addition ratio to 15% of the asphalt mass, while ensuring efficient crosslinking, avoiding side reactions caused by excessive anhydride, thereby significantly improving the reversible specific capacity of the hard carbon material. The oxygen atmosphere chemical crosslinking process of the present invention adopts a chemical crosslinking strategy under an oxygen atmosphere, reacts at 300°C for 10 hours, and realizes in-situ efficient crosslinking of anhydride and asphalt. This process effectively inhibits the rearrangement of the molten carbon layer of asphalt during the carbonization process and enhances the structural stability of the material. The carbonization temperature defined by the present invention promotes the full growth of the carbon layer by precisely controlling the carbonization temperature, increases the interlayer spacing of the asphalt-based hard carbon, thereby optimizing the sodium ion storage site, and finally obtaining a hard carbon material with a high sodium storage capacity. In summary, the present invention provides a safe, reliable, low-cost, simple process and highly controllable method for preparing hard carbon materials, which has significant technical advantages, broad application prospects and industrialization potential. The present invention is described in detail below through specific embodiments.

[0030] Example 1

[0031] This embodiment is used to illustrate the preparation method of the asphalt-based hard carbon material provided by the present invention, the asphalt-based hard carbon negative electrode sheet made using the asphalt-based hard carbon material, and the sodium ion battery using the asphalt-based hard carbon negative electrode sheet.

[0032] a. Mix asphalt and 3,4,9,10-perylenetetracarboxylic anhydride in a mass ratio of 20:3 to obtain a solid mixture.

[0033] b. Transfer the solid mixture obtained in step a to a heater and heat it at 300 °C for 10 h in an oxygen atmosphere for crosslinking to obtain an intermediate product;

[0034] c. Take out the crosslinked intermediate product, heat it to 600 °C at a heating rate of 5 °C / min in an argon atmosphere and hold for 1 h, then heat it to 1400 °C at a heating rate of 5 °C / min and hold for 1 h. After cooling to room temperature, the asphalt-based hard carbon material is obtained.

[0035] Mix the powder sample, conductive carbon black, CMC and SBR evenly according to a mass ratio of 85:10:2:3, add an appropriate amount of deionized water, stir and mix for 6 h to make a uniformly distributed slurry, and then coat the mixed slurry on a copper foil current collector. Vacuum dry the copper foil current collector coated with the slurry. After complete drying, make a negative electrode plate. In a vacuum glove box under an argon atmosphere, use a sodium metal sheet as the counter electrode, glass fiber as the separator, 1 mol / L NaPF6-EC / DEC (volume ratio 1:1) as the electrolyte, and add the prepared negative electrode plate to assemble a button battery.

[0036] The electrochemical performance test method is as follows: perform constant current charge and discharge on the above button battery, use a current density of 20 mAh / g for charge and discharge, and the test voltage range is 0 - 2 V. Record its charge and discharge capacity and the first Coulomb efficiency. The test results are shown in Table 1. The asphalt-based hard carbon prepared under this condition has a reversible sodium storage capacity of 319.76 mAh g -1 at a current density of -1 , as Figure 1 shown, the asphalt-based hard carbon prepared under this condition has a relatively large interlayer spacing of , indicating that it has been successfully transformed into an amorphous hard carbon material, which is beneficial to obtaining a high sodium storage capacity, as Figure 2 shown.

[0037] Example 2

[0038] Mix asphalt and 1,4,5,8-naphthalenetetracarboxylic dianhydride in a mass ratio of 20:3, and use the same conditions as in Example 1 to prepare the corresponding hard carbon material.

[0039] Assemble a button battery using the same method as in Example 1 and perform electrochemical tests under the same conditions. The test results are shown in Table 1. The asphalt-based hard carbon prepared under this condition has a reversible sodium storage capacity of 304.64 mAh g -1 at a current density of -1 , as Figure 1 shown; the interlayer spacing of the asphalt-based hard carbon prepared under this condition is , showing obvious hard carbon XRD peaks, as Figure 2as shown

[0040] Example 3

[0041] Asphalt and pyromellitic dianhydride were mixed at a mass ratio of 20:3, and other conditions were the same as in Example 1 to obtain the corresponding hard carbon material.

[0042] The button battery was assembled in the same method as in Example 1 and subjected to electrochemical tests under the same conditions. The test results are shown in Table 1. The asphalt-based hard carbon prepared under this condition had a reversible sodium storage capacity of 269.64 mAh g -1 at a current density of, as -1 shown; the interlayer spacing of the asphalt-based hard carbon prepared under this condition was Figure 1 which showed an obvious XRD peak shape of hard carbon, as shown. Figure 2 as shown

[0043] Comparative Example 1

[0044] This comparative example was basically the same as Example 1, except that no anhydride organic matter was added in this comparative example. The specific steps were as follows.

[0045] a. Transfer the asphalt to a heater and heat it at 300 °C for 10 h in an oxygen atmosphere for crosslinking;

[0046] b. Take out the crosslinked asphalt, heat it to 600 °C at a heating rate of 5 °C / min in an argon atmosphere and keep it for 1 h, then heat it to 1400 °C at a heating rate of 5 °C / min and keep it for 1 h. After cooling to room temperature, the asphalt-based hard carbon material was obtained.

[0047] The button battery was assembled in the same method as in Example 1 and subjected to electrochemical tests under the same conditions. The test results are shown in Table 1.

[0048] Comparative Example 2

[0049] This comparative example was basically the same as Example 1, except that the carbonization temperature in Example 1 was changed to 1300 °C. The specific steps were as follows.

[0050] a. Transfer the asphalt to a heater and heat it at 300 °C for 10 h in an oxygen atmosphere for crosslinking;

[0051] b. Take out the crosslinked asphalt, heat it to 600 °C at a heating rate of 5 °C / min in an argon atmosphere and keep it for 1 h, then heat it to 1300 °C at a heating rate of 5 °C / min and keep it for 1 h. After cooling to room temperature, the asphalt-based hard carbon material was obtained.

[0052] The button cells were assembled using the same method as in Example 1 and subjected to electrochemical tests under the same conditions. The test results are shown in Table 1.

[0053] Comparative Example 3

[0054] This comparative example is basically the same as Example 1, except that no anhydride organic matter was added in this comparative example, and the pitch was directly carbonized without pre-oxidation treatment. The specific steps are as follows.

[0055] a. The pitch was heated to 600 °C at a heating rate of 5 °C / min under an argon atmosphere and held for 1 h, then heated to 1400 °C at 5 °C / min and held for 1 h. After cooling to room temperature, the pitch-based hard carbon material was obtained.

[0056] The button cells were assembled using the same method as in Example 1 and subjected to electrochemical tests under the same conditions. The test results are shown in Table 1.

[0057] Comparative Example 4

[0058] The pitch and 3,4,9,10-perylene tetracarboxylic dianhydride were thoroughly mixed in a mass ratio of 10:1, and other conditions were the same as in Example 1 to obtain the corresponding hard carbon material.

[0059] The button cells were assembled using the same method as in Example 1 and subjected to electrochemical tests under the same conditions. The test results are shown in Table 1.

[0060] Comparative Example 5

[0061] The pitch and 3,4,9,10-perylene tetracarboxylic dianhydride were thoroughly mixed in a mass ratio of 10:3, and other conditions were the same as in Example 1 to obtain the corresponding hard carbon material.

[0062] The button cells were assembled using the same method as in Example 1 and subjected to electrochemical tests under the same conditions. The test results are shown in Table 1.

[0063] Comparative Example 6

[0064] The pitch and 3,4,9,10-perylene tetracarboxylic dianhydride were thoroughly mixed in a mass ratio of 20:3 and cross-linked by heating at 300 °C for 6 h in an oxygen atmosphere. Other conditions were the same as in Example 1 to obtain the corresponding hard carbon material.

[0065] The button cells were assembled using the same method as in Example 1 and subjected to electrochemical tests under the same conditions. The test results are shown in Table 1.

[0066] Comparative Example 7

[0067] Asphalt and 3,4,9,10-perylene tetracarboxylic dianhydride were fully mixed in a mass ratio of 20:3, and cross-linked by heating at 300 °C for 14 h in an oxygen atmosphere. Other conditions were the same as those in Example 1 to obtain the corresponding hard carbon material.

[0068] The button battery was assembled by the same method as in Example 1 and electrochemically tested under the same conditions. The test results are shown in Table 1.

[0069] Table 1. Test Results of Electrochemical Performance

[0070]

[0071] The experimental results show that for the sodium-ion battery prepared from the asphalt-based hard carbon material prepared in Example 1, with 1 mol / L NaPF6-EC / DEC as the electrolyte and a current density of 20 mA / g, the initial Coulombic efficiency reaches 75.64%, and the reversible capacity is 319.76 mAh / g; at a current density of 200 mA / g, the reversible capacity can still reach 189.14 mAh / g. In summary, the modified asphalt-based hard carbon material provided by the present invention has broad application prospects and is expected to be widely used in the field of sodium-ion batteries.

[0072] The above-described embodiments are only the preferred embodiments of the present invention, and not all the feasible embodiments of the present invention. For those of ordinary skill in the art, any obvious changes made without departing from the principle and spirit of the present invention should be considered to be included within the protection scope of the claims of the present invention.

Claims

1. A preparation method of an asphalt-based hard carbon material for a sodium-ion battery, characterized in that, It includes the following steps: a. Solid-phase mix asphalt with organic acid anhydrides to obtain a solid mixture; b. Crosslink the solid mixture obtained in step a under an oxygen atmosphere; to obtain an intermediate product c. Under an inert atmosphere, subject the intermediate product obtained in step b to low-temperature pre-carbonization and high-temperature carbonization in sequence to obtain the asphalt-based hard carbon material.

2. The preparation method of an asphalt-based hard carbon material for a sodium-ion battery according to claim 1, characterized in that, In step a, the softening point of the asphalt is not lower than 200 °C, and it includes one or more of petroleum asphalt, coal tar pitch, biomass asphalt, or coal liquefaction residue asphalt.

3. The preparation method of an asphalt-based hard carbon material for a sodium-ion battery according to claim 1, characterized in that, In step a, the organic acid anhydrides are one or more of phthalic anhydride, benzoic anhydride, pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, and 3,4,9,10-perylenetetracarboxylic dianhydride.

4. The preparation method of an asphalt-based hard carbon material for a sodium-ion battery according to claim 1, characterized in that, In step a, the mass ratio of asphalt to organic acid anhydrides is 1:50 to 100:

1.

5. The preparation method of an asphalt-based hard carbon material for a sodium-ion battery according to claim 1, characterized in that, In step b, the crosslinking temperature is 300 - 350 °C, and the duration is 2 - 14 h.

6. The preparation method of an asphalt-based hard carbon material for a sodium-ion battery according to claim 1, characterized in that, In step c, the low-temperature pre-carbonization conditions are: heating at a heating rate of 1 - 10 °C / min to 400 - 800 °C and holding for 1 - 2 hours.

7. The preparation method of an asphalt-based hard carbon material for a sodium-ion battery according to claim 1, characterized in that, In step c, the high-temperature carbonization conditions are: heating at a heating rate of 1 - 10 °C / min to 1000 - 1600 °C and holding for 1 - 3 h.

8. Application of the asphalt-based hard carbon material prepared by the preparation method according to any one of claims 1 - 7 in the preparation of the negative electrode of a sodium-ion battery.

9. Application of the asphalt-based hard carbon material prepared by the preparation method according to any one of claims 1 - 7 in the preparation of the negative electrode of a sodium-ion battery.

10. The application according to claim 9, characterized in that it is asphalt Application of the sodium-ion battery prepared from the hard carbon material in power supply for the manufacture of electric vehicles, mobile phones, laptop computers, electronic products, and mobile energy storage devices.

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