Preparation method of low-cost ethylene tar asphalt-based hard carbon material
By mixing ethylene tar asphalt with soluble starch and carbonizing it, low-cost ethylene tar asphalt-based hard carbon material is prepared, which solves the problem of insufficient structural stability and electrochemical performance of the negative electrode material of sodium ion battery, and achieves higher sodium storage capacity and electrochemical cycling rate performance.
Patent Information
- Application Number
- CN202510025344.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-08
- Publication Date
- 2025-05-06
AI Technical Summary
The existing sodium ion battery asphalt-based anode materials have large volume expansion, poor electron conductivity and small layer spacing during charging and discharging, which limit their application.
Low-cost ethylene tar asphalt-based hard carbon material is prepared by mixing ethylene tar asphalt with soluble starch in a certain proportion and pre-reacting and carbonizing in a tube furnace.
The layer spacing and ion diffusion rate of ethylene tar asphalt are improved, and its electrochemical cycle rate performance is enhanced, ensuring that there is still a sodium storage capacity of 93.6mAh/g~230.9mAh/g under large-scale current.
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Figure CN119929774A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of sodium ion battery materials, and in particular relates to a method for preparing a low-cost ethylene tar pitch-based hard carbon material. Background Art
[0002] Sodium-ion batteries have attracted widespread attention in recent years due to their abundant resources and potential low cost. Compared with lithium-ion batteries, the key advantage of sodium-ion batteries is that the sodium element is abundant, widely distributed and cheap. As the global demand for lithium resources increases and lithium prices rise, finding alternative technologies to lithium-ion batteries has become a research hotspot. Sodium-ion batteries are similar to lithium-ion batteries in working principles, but because the ionic radius of sodium ions is larger, they face many challenges in electrode material design and electrochemical performance optimization.
[0003] Among them, the development of low-cost sodium-ion battery electrode materials is the key to its development. Asphalt-based negative electrode materials for sodium-ion batteries have been studied, such as: Wang C, Cai H, Zheng S, et al. Pitch-based carbon anode for high-energy and long-life sodium-ion battery [J]. Electrochimica Acta, 2024, 504: 144956.; Wang L, Xu Z, Lin P, et al. Oxygen-Crosslinker Effect on the Electrochemical Characteristics of Asphalt-Based Hard Carbon Anodes for Sodium-Ion Batteries [J]. Advanced Energy Materials, 2403084.; However, asphalt-based negative electrode materials will produce huge volume expansion, poor electronic conductivity and small interlayer spacing during the charge and discharge process of sodium-ion batteries, limiting their further application. In view of the above problems, asphalt-based negative electrode materials can be improved by morphological adjustment, heteroatom doping and preparation of composite materials. Among them, the preparation of composite materials has the advantages of low cost, simple preparation method, and wide source of raw materials. Therefore, the preparation of composite materials is the focus of research on improving asphalt-based negative electrode materials.
[0004] The selection of suitable materials and asphalt-based negative electrode materials is the focus of research. Recent studies have shown that mixing hard carbon materials with large interlayer spacing with ethylene tar pitch with poor cycle performance can effectively avoid and suppress the shortcomings of ethylene tar pitch. After compounding, the microcrystalline structure of ethylene tar pitch is changed, thereby improving the electrochemical performance of the material. However, in previous reports, composite materials require complex organic synthesis, resulting in high material costs, long experiments, and demanding preparation conditions, making it difficult to mass produce. Summary of the invention
[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing a low-cost ethylene tar pitch-based hard carbon material, so as to solve the problems of poor structural stability, difficulty in charging and discharging at high current rates and low sodium storage capacity when using asphalt as a negative electrode material for sodium ion batteries.
[0006] To achieve the above object, the present invention is implemented through the following technical solutions:
[0007] A method for preparing a low-cost ethylene tar pitch-based hard carbon material comprises the following steps:
[0008] 1) Grind and mix ethylene tar pitch and soluble starch in a mass ratio of (9:1) to (7:3) evenly;
[0009] 2) placing the mixed material uniformly mixed in step 1) into a tube furnace, maintaining the temperature at 200-350° C. for 1.5-2.5 hours, and cooling to room temperature to obtain a precursor material;
[0010] 3) Put the precursor material into a pulverizer, grind it and pass it through a 100-mesh sieve;
[0011] 4) Keep the sample after passing through the sieve at a constant temperature of 1100-1700°C for 0.5-2.5 hours and cool it to room temperature.
[0012] The softening point of the ethylene tar pitch is 140-280°C, and the coking value is 40%-60%.
[0013] The soluble starch is one or more of the starches prepared from corn, sweet potato or potato.
[0014] In step 2), the tubular furnace is filled with oxygen atmosphere or air atmosphere.
[0015] In step 3), the tubular furnace is filled with an inert atmosphere.
[0016] The inert atmosphere is nitrogen or argon passing through the tubular furnace.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] The present invention uses ethylene tar pitch and soluble starch to prepare the negative electrode material of sodium ion battery. Ethylene tar pitch is more easily graphitized during the carbonization process, and the smaller interlayer spacing of the graphite layer will seriously affect its sodium storage performance. The ethylene tar pitch is pretreated, and the ethylene tar pitch and the soluble starch are pre-reacted to make the two first undergo a cross-linking reaction to enhance the structural stability of the precursor, and then carbonized under an inert atmosphere, which can increase the interlayer spacing and ion diffusion rate of the ethylene tar pitch, thereby improving its electrochemical cycle rate performance. The prepared ethylene tar pitch hard carbon material is applied to the negative electrode material of the sodium ion half-cell. At a current density of 1A / g, the capacity after 500 cycles is still 93.6mAh / g to 230.9mAh / g, which shows that the ethylene tar pitch hard carbon material has considerable application prospects in electrochemical energy storage. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a flow chart for the preparation of ethylene tar pitch-based hard carbon materials.
[0020] Figure 2 3 is the XRD diagram of the ethylene tar pitch-based hard carbon material prepared in Example 1, Example 2, Example 3 and Comparative Example.
[0021] Figure 3 It is a cycle performance diagram of the ethylene tar pitch-based hard carbon material prepared in Example 1, Example 2, Example 3, and Comparative Example.
[0022] Figure 4 It is a rate performance diagram of the ethylene tar pitch-based hard carbon material prepared in Example 1, Example 2, Example 3, and Comparative Example.
[0023] Figure 5 (a) is Example 1, (b) is Example 2, (c) is Example 3, and (d) is the SEM image of the ethylene tar pitch-based hard carbon material prepared in the comparative example.
[0024] Figure 6 (a) is Example 1, (b) is Example 2, (c) is Example 3, and (d) is the TEM image of the ethylene tar pitch-based hard carbon material prepared in the comparative example. DETAILED DESCRIPTION
[0025] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.
[0026] Example 1
[0027] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0028] 1) Ethylene tar pitch (softening point 240°C, coking value 42%) and (sweet potato) soluble starch were mixed in a mass ratio of 9:1;
[0029] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0030] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0031] 4) The powder is taken out from the pulverizer, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0032] Example 2
[0033] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0034] 1) Ethylene tar pitch (softening point 240°C, coking value 42%) and (sweet potato) soluble starch were mixed in a mass ratio of 8:2;
[0035] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0036] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0037] 4) The powder is taken out from the pulverizer, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0038] Example 3
[0039] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0040] 1) Ethylene tar pitch (softening point 240°C, coking value 42%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0041] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0042] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0043] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0044] Example 4
[0045] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0046] 1) Ethylene tar pitch (softening point 240°C, coking value 50%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0047] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 200° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0048] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0049] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0050] Example 5
[0051] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0052] 1) Ethylene tar pitch (softening point 240°C, coking value 50%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0053] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 350° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0054] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0055] 4) The powder is taken out from the pulverizer, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0056] Example 6
[0057] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0058] 1) Ethylene tar pitch (softening point 240°C, coking value 50%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0059] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 1.5 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0060] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0061] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0062] Example 7
[0063] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0064] 1) Ethylene tar pitch (softening point 240°C, coking value 50%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0065] 2) The mixed material is placed in a tube furnace, kept at a constant temperature of 250° C. for 2.5 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0066] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0067] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0068] Example 8
[0069] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0070] 1) Ethylene tar pitch (softening point 240°C, coking value 50%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0071] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0072] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0073] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1100° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0074] Example 9
[0075] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0076] 1) Ethylene tar pitch (softening point 240°C, coking value 50%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0077] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0078] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0079] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1500° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0080] Example 10
[0081] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0082] 1) Ethylene tar pitch (softening point 240°C, coking value 50%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0083] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0084] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0085] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1700° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0086] Embodiment 11
[0087] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0088] 1) Ethylene tar pitch (softening point 150°C, coking value 52%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0089] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0090] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0091] 4) The powder is taken out from the pulverizer, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0092] Example 12
[0093] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0094] 1) Ethylene tar pitch (softening point 200°C, coking value 55%) and (sweet potato) soluble starch are mixed in a mass ratio of 7:3;
[0095] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0096] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0097] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0098] Example 13
[0099] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0100] 1) Ethylene tar pitch (softening point 220°C, coking value 60%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0101] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0102] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0103] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0104] Embodiment 14
[0105] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0106] 1) Ethylene tar pitch (softening point 180°C, coking value 42%) and (potato) soluble starch were mixed in a mass ratio of 7:3;
[0107] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0108] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0109] 4) The powder is taken out from the pulverizer, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0110] Embodiment 15
[0111] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0112] 1) Ethylene tar pitch (softening point 180°C, coking value 42%) and (corn) soluble starch were mixed in a mass ratio of 7:3;
[0113] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0114] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0115] 4) The powder is taken out from the pulverizer, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0116] Example 16
[0117] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0118] 1) Ethylene tar pitch (softening point 180°C, coking value 42%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0119] 2) placing the mixed materials into a tube furnace, maintaining a constant temperature of 250° C. for 2 hours under an oxygen atmosphere, and cooling to room temperature to obtain a precursor material;
[0120] 3) Put the precursor material into a grinder and grind it for 20 minutes, and then pass it through a 100-mesh sieve;
[0121] 4) The powder is taken out from the pulverizer, kept at a constant temperature of 1300° C. for 2 hours under an argon atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0122] Embodiment 17
[0123] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0124] 1) Ethylene tar pitch (softening point 180°C, coking value 42%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0125] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0126] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0127] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 2 hours under a nitrogen atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0128] Embodiment 18
[0129] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0130] 1) Ethylene tar pitch (softening point 180°C, coking value 42%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0131] 2) placing the mixed materials into a tube furnace, maintaining a constant temperature of 250° C. for 2 hours under an oxygen atmosphere, and cooling to room temperature to obtain a precursor material;
[0132] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0133] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 2 hours under a nitrogen atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0134] Embodiment 19
[0135] See Figure 1 , a method for preparing a low-cost ethylene tar pitch-based hard carbon material, comprising the following steps:
[0136] 1) Ethylene tar pitch (softening point 180°C, coking value 42%) and (sweet potato) soluble starch were mixed in a mass ratio of 7:3;
[0137] 2) The mixed materials are placed in a tube furnace, kept at a constant temperature of 250° C. for 2 hours under air atmosphere, and cooled to room temperature to obtain a precursor material;
[0138] 3) Put the precursor material into a grinder and grind it for 20 minutes, and pass it through a 100-mesh sieve;
[0139] 4) The powder in the pulverizer was taken out, kept at a constant temperature of 1300° C. for 1 hour under a nitrogen atmosphere, and cooled to room temperature to obtain a low-cost ethylene tar pitch-based hard carbon material.
[0140] Comparative Example
[0141] according to Figure 1 A preparation flow chart of a low-cost method for preparing ethylene tar pitch-based hard carbon material, comprising the following steps:
[0142] Pure ethylene tar pitch (softening point 180°C, coking value 42%) was kept at a constant temperature of 1300°C for 2 hours under an argon atmosphere and cooled to room temperature to obtain ethylene tar pitch soft carbon material as a comparison material.
[0143] The prepared samples were made into electrode sheets, which were assembled into button batteries in the order of negative electrode shell, sodium sheet, diaphragm, negative electrode sheet, gasket, spring sheet, and positive electrode shell to test the electrochemical performance.
[0144] Figure 2 The X-ray diffraction (XRD) diagrams of the samples prepared in Example 1, Example 2, Example 3 and the comparative example show that the two broad diffraction peaks at around 24° and 43° correspond to the (002) and (100) crystal planes, showing the amorphous carbon structure of the ethylene tar pitch-based hard carbon material, and as the amount of soluble starch added increases, the intensity of the (002) peak gradually weakens, indicating that the degree of graphitization of the material decreases; and the (002) characteristic peak of the material gradually shifts to the left, proving that its interlayer spacing gradually increases.
[0145] Figure 3 The cycling performance of ethylene tar pitch based hard carbon materials (9:1, 8:2, 7:3) and ethylene tar pitch soft carbon materials under the conditions of current density of 1A / g and voltage range of 0.01V-3.0V. As can be seen from the figure, the ethylene tar pitch hard carbon material (9:1) has a high cycling performance under the conditions of current density of 1A g -1 After 500 cycles, the sodium storage capacity is 105.3 mAh / g, and the capacity retention rate is 87.1%. Ethylene tar pitch hard carbon material (8:2) at a current density of 1A g -1 The sodium storage capacity after 500 cycles in the voltage range of 0.01V-3.0V is 170.6mAh g -1 , capacity retention rate 85%; ethylene tar pitch hard carbon material (7:3) at a current density of 1A g -1 The sodium storage capacity after 500 cycles is 230.9 mAh g -1 , capacity retention rate 88.2%; ethylene tar pitch soft carbon material at a current density of 1A -1 The sodium storage capacity after 500 cycles is 93.6 mAh g -1 , capacity retention rate is 84.3%.
[0146] Figure 4The figure shows the rate performance of ethylene tar pitch hard carbon material (9:1, 8:2, 7:3) and ethylene tar pitch soft carbon material under the voltage range of 0.01V-3.0V. -1 , 0.06A g -1 , 0.12A g -1 , 0.3A g -1 , 0.6A g -1 , 1.2A g -1 , and the sodium storage capacity is 147.9 mAh g -1 , 140mAh g -1 , 134.6mAh g -1 , 125.6mAh g -1 , 116.9mAh g -1 , 107.4mAh g -1 ; Ethylene tar pitch hard carbon material (8:2) at a current density of 0.03A g -1 , 0.06A g -1 , 0.12A g -1 , 0.3Ag -1 , 0.6Ag -1 , 1.2Ag -1 , and the sodium storage capacity is 201.7 mAh g -1 , 196.4mAh g -1 , 187.5mAh g -1 、177.3mAh g -1 、163.2mAh g -1 、150mAhg -1 ; Ethylene tar pitch hard carbon material (7:3) at a current density of 0.03Ag -1 , 0.06Ag -1 , 0.12Ag -1 , 0.3Ag -1 , 0.6Ag -1 , 1.2Ag -1 , and the sodium storage capacity is 315.2 mAh g -1 、303.6mAh g -1 , 296.9mAh g -1 , 284.6mAh g -1 、269.1mAh g -1 , 249.2mAh g -1 ; Ethylene tar pitch soft carbon material at a current density of 0.03A g -1 , 0.06A g -1 , 0.12Ag-1 , 0.3Ag -1 , 0.6A g -1 , 1.2Ag -1 , and the sodium storage capacity is 90.4 mAh g -1 、90.8mAh g -1 、89.5mAhg -1 、86.1mAh g -1 、82.9mAh g -1 、81.3mAh g -1 When the current density is increased from 1.2A -1 Back to 0.03Ag again -1 After 10 cycles, the ethylene tar pitch hard carbon material (7:3) still has 332.6 mAh g -1 The sodium storage capacity is significantly higher than that of the ethylene tar pitch soft carbon material in the comparative example. This is mainly due to the fact that the material after the reaction of ethylene tar pitch and soluble starch pretreatment and then high-temperature carbonization has a large interlayer spacing and good conductivity, thereby improving the overall electrochemical performance.
[0147] Depend on Figure 5 (d) It can be seen that the microstructure of pure ethylene tar pitch after carbonization is composed of irregular and rough small particles, and some small particles have agglomerated into large particles, which may affect the diffusion of sodium ions. Figure 5 (a)-(c) show that as the amount of soluble starch added increases, the particle size of the material becomes uniform and there is no agglomeration, which will lead to more complete contact with the electrolyte and faster sodium storage kinetics.
[0148] Depend on Figure 6 (d) It can be seen that the carbonization of pure ethylene tar pitch mainly forms a long-range ordered graphite microcrystalline structure; Figure 6 (a)-(c) As the amount of soluble starch added increases, the material changes from short-range order to disorder, which indicates that the degree of graphitization of the material decreases, which is consistent with the analysis in XRD.
[0149] The low-cost ethylene tar pitch-based hard carbon material prepared in each embodiment is applied to the negative electrode material of the sodium ion half-cell. The capacity and capacity retention rate after 500 cycles at a current density of 1 A / g are shown in Table 1.
[0150] Table 1
[0151] Implementation Sodium storage capacity after 500 cycles at 1A / g (mAh / g) Capacity retention rate (%) Example 1 105.3 87.1 Example 2 170.6 85 Example 3 230.9 88.2 Example 4 210.3 82.3 Example 5 220.5 81.4 Example 6 215.7 81.3 Example 7 211.5 82.2 Example 8 164.5 75.2 Example 9 198.5 79.9 Example 10 185.4 82.2 Embodiment 11 210.3 85.3 Example 12 220.5 86.4 Example 13 215.7 85.3 Embodiment 14 198.3 82.2 Embodiment 15 195.7 80.7 Example 16 225.9 87.2 Embodiment 17 221.8 87.6 Embodiment 18 218.6 86.4 Embodiment 19 189.6 82.3 Comparative Example 93.6 84.3
[0152] The above electrochemical experimental results show that by mixing ethylene tar pitch with soluble starch carbon, the interlayer spacing of ethylene tar pitch is effectively increased and the diffusion rate of sodium ions in its structure is accelerated, thereby improving its electrochemical cycle rate performance.
[0153] Ethylene tar pitch is more prone to graphitization during the carbonization process, and the smaller interlayer spacing of the graphite layer will seriously affect its sodium storage performance. Ethylene tar pitch is pretreated, and ethylene tar pitch is pre-reacted with soluble starch in air to make the two undergo cross-linking reaction first, enhance the structural stability of the precursor, and then carbonize under argon atmosphere to obtain ethylene tar pitch-based hard carbon material. From the analysis of structure and electrochemical performance, it is found that the introduction of soluble starch increases the interlayer spacing and ion diffusion rate of ethylene tar pitch, thereby improving its electrochemical cycle rate performance.
Claims
1. A method for preparing a low-cost ethylene tar pitch-based hard carbon material, characterized in that: The following steps are involved: 1) Grind and mix ethylene tar pitch and soluble starch in a mass ratio of (9:1) to (7:3) evenly; 2) placing the mixed material uniformly mixed in step 1) into a tube furnace, maintaining the temperature at 200-350° C. for 1.5-2.5 hours, and cooling to room temperature to obtain a precursor material; 3) Put the precursor material into a pulverizer, grind it and pass it through a 100-mesh sieve; 4) Keep the sample after passing through the sieve at a constant temperature of 1100-1700°C for 0.5-2.5 hours and cool it to room temperature.
2. The method for preparing a low-cost ethylene tar pitch-based hard carbon material according to claim 1, characterized in that: The softening point of the ethylene tar pitch is 140-280°C, and the coking value is 40%-60%.
3. The method for preparing a low-cost ethylene tar pitch-based hard carbon material according to claim 1, characterized in that: The soluble starch is one or more of the starches prepared from corn, sweet potato or potato.
4. The method for preparing a low-cost ethylene tar pitch-based hard carbon material according to claim 1, characterized in that: In step 2), the tubular furnace is filled with oxygen atmosphere or air atmosphere.
5. The method for preparing a low-cost ethylene tar pitch-based hard carbon material according to claim 1, characterized in that: In step 3), the tubular furnace is filled with an inert atmosphere.
6. The method for preparing a low-cost ethylene tar pitch-based hard carbon material according to claim 5, characterized in that: The inert atmosphere is nitrogen or argon passing through the tubular furnace.