Coal pitch-based composite hard carbon material as well as preparation method and application thereof
By combining coal tar pitch with organometallic compounds, a porous carbon framework and composite structure are formed, which solves the problems of specific capacity and conductivity of coal tar pitch-based hard carbon materials in sodium-ion batteries and achieves a high-efficiency improvement in electrochemical performance.
Patent Information
- Application Number
- CN202511293473.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-11
- Publication Date
- 2025-11-28
AI Technical Summary
Existing coal tar pitch-based hard carbon materials suffer from low specific capacity, poor conductivity, and poor structural fatigue resistance in sodium-ion batteries, which limits their application in sodium-ion batteries.
By mixing coal tar pitch with organometallic compounds such as dipotassium ethylenediaminetetraacetate or disodium ethylenediaminetetraacetate and then performing pre-carbonization and high-temperature carbonization treatments, a porous carbon skeleton and composite structure are formed, increasing the interlayer spacing and improving the sodium storage performance and stability of the material.
The prepared coal tar pitch-based composite hard carbon material achieved a reversible capacity of 335.78 mAh g⁻¹ at a current density of 0.03 Ag⁻¹, with an initial coulombic efficiency of 93.2%, significantly improving the electrochemical performance of sodium-ion batteries.
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Figure CN121020554A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of negative electrode materials of alkali metal ion batteries, and particularly relates to a coal pitch-based composite hard carbon material and a preparation method and application thereof. BACKGROUND
[0002] Sodium-ion batteries, as an important electrochemical energy storage device, have attracted extensive attention due to the abundant reserves of sodium in the earth's crust, low cost and similar working principle to lithium-ion batteries. However, the development of sodium-ion batteries still faces many challenges, and the performance of the negative electrode material is one of the key factors restricting the performance improvement.
[0003] Coal pitch, as an important by-product of coal chemical industry or petroleum chemical industry, has the advantages of wide source, low price and high carbon yield. At present, hard carbon and soft carbon materials are considered to be the most potential negative electrode materials for sodium-ion batteries, but their sodium storage performance, cycle stability and specific capacity still need to be further improved. The derived carbon negative electrode material prepared from coal pitch has unique advantages in sodium-ion batteries. First, the coal pitch-based derived carbon negative electrode material has a high sodium storage capacity, which can meet the demand for energy density of sodium-ion batteries. Second, the material has good cycle stability and can maintain the stability of the structure during charging and discharging, prolonging the service life of the battery. In addition, the preparation process of the coal pitch-based derived carbon negative electrode material is relatively simple and has low cost, which is beneficial to the large-scale commercial application of sodium-ion batteries. However, the direct carbonization of coal pitch has the disadvantages of insufficient interlayer spacing, limited sodium storage sites and insufficient cycle stability. Therefore, the development of suitable negative electrode materials is crucial for the commercialization of sodium-ion batteries. SUMMARY
[0004] Coal pitch is prone to form highly graphitized structure soft carbon material after direct pyrolysis, and directly used as a negative electrode material for sodium-ion batteries has poor performance, thus having certain limitations. In view of the above problems, the application provides a coal pitch-based composite hard carbon material and a preparation method and application thereof. The coal pitch-based composite hard carbon material obtained by the application can be used as a negative electrode material for sodium-ion batteries, which can significantly improve the reversible specific capacity of the battery and obtain a high initial coulombic efficiency.
[0005] In a first aspect, the application provides a preparation method of a coal pitch-based composite hard carbon material, which comprises the following steps: uniformly mixing coal pitch, a metal organic compound and a solvent, drying to obtain a mixture, acid washing after pre-carbonization treatment, washing to neutral, drying and high-temperature carbonization treatment to obtain the coal pitch-based composite hard carbon material.
[0006] Compared with the prior art, the application solves the problem that polycyclic aromatic hydrocarbon molecules are prone to form close layered arrangement due to strong pi-pi interaction during coal pitch pyrolysis, and finally change into ordered graphite structure, resulting in increased brittleness and decreased energy storage performance of the material, by adding metal organic compounds which can produce intercalation effect between aromatic layers, increasing the interlayer spacing by physical isolation, breaking the intermolecular stacking mode, effectively reducing the size and arrangement regularity of carbon layers, and increasing the surface defects and the formation of rich closed pores in the hard carbon material.
[0007] Further, the metal organic compound is dipotassium ethylenediaminetetraacetate or disodium ethylenediaminetetraacetate, and the solvent includes water and anhydrous ethanol.
[0008] Further, the metal organic compound, water and anhydrous ethanol are used in a ratio of (0.2-3) g:(10-30) mL:(5-20) mL.
[0009] Further, the mass ratio of the coal pitch and the metal organic compound is 1:(0.2-3).
[0010] Further, the mass ratio of the coal pitch and the metal organic compound is 1:(0.2-1).
[0011] Further, the mass ratio of the coal pitch and the metal organic compound is 1:1.
[0012] By optimizing the ratio of the coal pitch and the metal organic compound, the coal pitch coats the pores of the porous material into closed pores, and the trace closed pores generated by high-temperature pyrolysis, and the ratio between the metal organic compound and the coal pitch raw material is the key to determine the final hard carbon structure and performance, and a too low ratio cannot play a significant role, and a too high ratio will lead to excessive increase of the specific surface area caused by activation and reduction of the hard carbon yield, which is not conducive to the improvement of key indicators such as capacity and initial efficiency.
[0013] Further, the pre-carbonization treatment is to heat to 600 DEG C at a rate of 10 DEG C / min in an inert gas atmosphere, and keep for 2 h.
[0014] The role of the pre-carbonization treatment is:
[0015] 1) Recombination of molecular structure: pre-carbonization makes the metal organic compound crack to form a porous carbon skeleton, and the coal pitch melts and penetrates, preliminarily building a composite structure;
[0016] 2) Pore regulation: by controlling the escape of cracking gas and the filling of coal pitch, hierarchical pores (2-50 nm) are formed, and nitrogen species (pyridine nitrogen and pyrrole nitrogen) are stabilized;
[0017] 3) Interface optimization: by pre-carbonization treatment, the chemical bonding of the two phases is promoted, the phase separation at high temperature is inhibited, the defect density is reduced, and the material stability is improved.
[0018] Further, the high-temperature carbonization treatment is: under the inert gas atmosphere, the temperature is raised to 1200 DEG C at a rate of 10 DEG C / min, and the temperature is kept for 3h.
[0019] The high-temperature carbonization treatment is to completely melt the coal pitch melt at high temperature and fill the open pores generated by the pre-carbonization to form closed pores, and also form a dense graphite layer on the surface of the porous carbon.
[0020] In a second aspect, the present application provides a coal pitch-based composite hard carbon material prepared by the above preparation method.
[0021] In a third aspect, the present application provides an application of the above coal pitch-based composite hard carbon material in preparing a sodium ion battery negative electrode material.
[0022] Compared with the prior art, the present application has the following advantages and technical effects:
[0023] The present application provides a preparation method of a coal pitch-based composite hard carbon material, which changes the mass ratio of coal pitch and metal organic compound (dipotassium ethylenediaminetetraacetate or disodium ethylenediaminetetraacetate) to obtain the coal pitch-based composite hard carbon material, and the coal pitch-based composite hard carbon material is more suitable for sodium ion batteries as a negative electrode material, and solves the technical problems of low specific capacity, poor conductivity and poor structure fatigue resistance of the existing coal pitch-based hard carbon.
[0024] The coal pitch-based composite hard carbon material prepared by the present application as a sodium ion battery negative electrode has low preparation cost, simple process and excellent electrochemical performance, and can provide a technical basis for commercial preparation of coal-based hard carbon negative electrode materials for sodium ion batteries. -1 The reversible capacity of the half-cell can reach 335.78 mAhg -1 -1 under a current density of 0.03 Ag BRIEF DESCRIPTION OF DRAWINGS
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0026] Figure 1 SEM image of the coal pitch-based composite hard carbon material prepared in Example 1;
[0027] Figure 2A sodium-ion battery prepared using a coal-tar pitch-based composite hard carbon material prepared in Example 1 as a negative electrode material had a charge-discharge curve graph at a current density of 0.03 Ag -1
[0028] Figure 3 A sodium-ion battery prepared using a coal-tar pitch-based composite hard carbon material prepared in Example 2 as a negative electrode material had a charge-discharge curve graph at a current density of 0.03 Ag -1
[0029] Figure 4 An SEM image of a coal-tar pitch-based composite hard carbon material prepared in Example 3;
[0030] Figure 5 A sodium-ion battery prepared using a coal-tar pitch-based composite hard carbon material prepared in Example 3 as a negative electrode material had a charge-discharge curve graph at a current density of 0.03 Ag -1
[0031] Figure 6 A sodium-ion battery prepared using a coal-tar pitch-based composite hard carbon material prepared in Example 4 as a negative electrode material had a charge-discharge curve graph at a current density of 0.03 Ag -1
[0032] Figure 7 An SEM image of a coal-tar pitch-based composite hard carbon material prepared in Example 5;
[0033] Figure 8 A sodium-ion battery prepared using a coal-tar pitch-based composite hard carbon material prepared in Example 5 as a negative electrode material had a charge-discharge curve graph at a current density of 0.03 Ag -1
[0034] Figure 9 A sodium-ion battery prepared using a coal-tar pitch-based composite hard carbon material prepared in Example 6 as a negative electrode material had a charge-discharge curve graph at a current density of 0.03 Ag -1
[0035] Figure 10 An SEM image of a coal-tar pitch-based composite hard carbon material prepared in Example 7;
[0036] Figure 11 A sodium-ion battery prepared using a coal-tar pitch-based composite hard carbon material prepared in Example 7 as a negative electrode material had a charge-discharge curve graph at a current density of 0.03 Ag -1
[0037] Figure 12 A sodium-ion battery prepared using a coal-tar pitch-based composite hard carbon material prepared in Example 8 as a negative electrode material had a charge-discharge curve graph at a current density of 0.03 Ag -1
[0038] Figure 13 SEM image of the carbon material prepared in Comparative Example 1;
[0039] Figure 14 To prepare a sodium-ion battery using the porous carbon material prepared in Comparative Example 1 as the anode material, a 0.03 Ag... -1 Charge-discharge curves at current density;
[0040] Figure 15 SEM image of the porous carbon material prepared in Comparative Example 2;
[0041] Figure 16 To prepare a sodium-ion battery using the porous carbon material prepared in Comparative Example 2 as the anode material, a 0.03 Ag... -1 Charge-discharge curves at current density. Detailed Implementation
[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0043] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0044] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0045] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0046] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0047] The embodiment of the present application provides a preparation method of coal-tar-based composite hard carbon material, which comprises the following steps:
[0048] S1. The original coal-tar is weighed and crushed to obtain coal-tar powder;
[0049] S2. According to the mass ratio, the coal-tar powder and metal organic compound are weighed, the metal organic compound, deionized water and anhydrous ethanol are mixed to obtain a transparent solution, the coal-tar powder is added into the transparent solution and uniformly mixed, and then the mixture is placed into a blast drying oven for evaporation and drying to obtain a mixture;
[0050] S3. The mixture is placed into a corundum boat and placed into a tube furnace for pre-carbonization treatment to obtain a preliminary black product, the black product is sufficiently pickled and washed to neutral, and then filtered and dried to obtain a black powder;
[0051] S4. The black powder is placed into a corundum boat and placed into a tube furnace for high-temperature carbonization treatment to obtain the coal-tar-based composite hard carbon material.
[0052] In some preferred embodiments of the present application, the metal organic compound is di-potassium ethylenediaminetetraacetate or di-sodium ethylenediaminetetraacetate.
[0053] In some preferred embodiments of the present application, the amount ratio of the metal organic compound, water and anhydrous ethanol is (0.2-3) g:(10-30) mL:(5-20) mL.
[0054] In some preferred embodiments of the present application, the mass ratio of the coal-tar and the metal organic compound is 1:(0.2-3), for example, the mass ratio of the coal-tar and the metal organic compound is 1:0.2, 1:0.5, 1:1 and 1:3.
[0055] In some preferred embodiments of the present application, the pre-carbonization treatment is as follows: under the atmosphere of inert gas, the temperature is raised to 600 DEG C at a rate of 10 DEG C / min, and the temperature is kept for 2 h.
[0056] In some preferred embodiments of the present application, the high-temperature carbonization treatment is as follows: under the atmosphere of inert gas, the temperature is raised to 1200 DEG C at a rate of 10 DEG C / min, and the temperature is kept for 3 h.
[0057] The embodiment of the present application further provides a coal-tar-based composite hard carbon material prepared by the preparation method.
[0058] The embodiment of the present application further provides an application of the coal-tar-based composite hard carbon material in preparing a sodium ion battery negative electrode material.
[0059] The softening point of the original coal-tar used in the embodiment of the present application is 280 DEG C.
[0060] The concentration of the dilute hydrochloric acid used in the examples and comparative examples of the present application is 2 mol / L.
[0061] Example 1 Preparation method of coal pitch-based composite hard carbon material
[0062] S1. The raw coal pitch was subjected to crushing treatment to obtain coal pitch powder.
[0063] S2. 0.2 g of dipotassium ethylenediaminetetraacetate, 10 mL of deionized water and 5 mL of anhydrous ethanol were placed in a beaker, mixed to obtain a transparent solution, 1 g of coal pitch powder was added to the transparent solution, mixed uniformly, and then placed in a blast drying oven for evaporation and drying (150℃, 6 h) to obtain a mixture.
[0064] S3. The mixture of S2 was placed in a corundum boat, and the corundum boat was placed in a tube furnace for pre-carbonization treatment: under argon atmosphere, the temperature was raised to 600℃ at a rate of 10℃ / min, and the temperature was kept for 2 h to obtain a preliminary black product. The preliminary black product was placed in dilute hydrochloric acid and stirred for 12 h. The product was washed to neutral with deionized water, and then suction filtration was performed. The obtained black product was placed in a blast drying oven for drying (150℃, 3 h) to obtain a black powder.
[0065] S4. The black powder of S3 was placed in a corundum boat, and the corundum boat was placed in a tube furnace for high-temperature carbonization treatment: under argon atmosphere, the temperature was raised to 1200℃ at a rate of 10℃ / min, and the temperature was kept for 3 h to obtain a coal pitch-based composite hard carbon material.
[0066] Figure 1 The SEM image of the coal pitch-based composite hard carbon material prepared in Example 1 can be seen from Figure 1 It can be seen that the material is irregularly blocky. Since the content of dipotassium ethylenediaminetetraacetate is extremely low and is completely wrapped, its activation and pore-forming effect is small, and the material cannot form a rich multi-level pore structure (micropore, mesopore). The final product is closer to coal pitch directly carbonized, has a dense structure with low specific surface area and low porosity, lacks a fast channel for ion transmission, and the dense structure and closed surface make it difficult for the electrolyte to be infiltrated. The diffusion path of sodium ions in the material is long and the resistance is large.
[0067] The coal-tar pitch-based composite hard carbon material prepared in Example 1 was used as a negative electrode material to assemble a sodium-ion battery. The specific assembly method was as follows: the coal-tar pitch-based composite hard carbon material, Ketjen black (purchased from Guangdong Candlelight New Energy Technology Co., Ltd., model Ketjenblack ECP-600JD, hereinafter the same), and sodium carboxymethyl cellulose (purchased from Guangdong Candlelight New Energy Technology Co., Ltd., model Ketjenblack CMC2200, hereinafter the same) were mixed and ground in a mass ratio of 8:1:1. The fine powder obtained by grinding was added to 1 mL of deionized water, and the slurry with suitable viscosity was obtained by further grinding. The slurry was uniformly coated on a copper foil using a coater, and then vacuum dried (110°C, 12 h) after air drying. The copper foil was cut into a circular negative electrode sheet with a diameter of 12 mm using a sheet cutting machine. The half battery was assembled in an argon-filled glove box, a metal sodium was used as a counter electrode, 1 mol NaPF6 was dissolved in 1,2-dimethoxyethane to serve as an electrolyte, and a CR2032 type button cell was assembled. After standing for 8 h, electrochemical charge and discharge tests were performed. The test voltage range was 0.01-3 V, and the current density was 0.03 Ag -1 . The test results are shown in Figure 2 , the reversible specific capacity was 244 mAhg -1 , and the initial coulombic efficiency was 89.01%.
[0068] Example 2
[0069] The same as Example 1, except that the di-potassium ethylenediaminetetraacetate was replaced by di-sodium ethylenediaminetetraacetate.
[0070] The coal-tar pitch-based composite hard carbon material prepared in Example 2 was used as a negative electrode material to assemble a sodium-ion battery. The specific assembly method was the same as that in Example 1. After standing for 8 h, electrochemical charge and discharge tests were performed on the assembled button cell. The test conditions were the same as those in Example 1. The test results are shown in Figure 3 , the reversible specific capacity was 254.57 mAhg -1 , and the initial coulombic efficiency was 98.84%.
[0071] Example 3 A preparation method of a coal-tar pitch-based composite hard carbon material
[0072] S1. The raw coal-tar pitch was subjected to a crushing treatment to obtain a coal-tar pitch powder.
[0073] S2. 0.5 g of di-potassium ethylenediaminetetraacetate, 15 mL of deionized water, and 10 mL of anhydrous ethanol were placed in a beaker, mixed to obtain a transparent solution, 1 g of the coal-tar pitch powder was added to the transparent solution, and mixed uniformly. The mixture was then placed in a blast oven for evaporation and drying (150°C, 6 h) to obtain a mixture.
[0074] S3. The mixture of S2 was put into a corundum boat, and the corundum boat was placed in a tube furnace for pre-carbonization treatment: under argon atmosphere, the temperature was raised to 600℃ at a rate of 10℃ / min, and the temperature was kept for 2h to obtain a preliminary black product; the preliminary black product was placed in dilute hydrochloric acid and stirred for 12h, then the product was washed to neutral with deionized water, and suction filtration was performed, and the obtained black product was placed in a blast drying oven (150℃, 3h) to obtain a black powder;
[0075] S4. The black powder of S3 was put into a corundum boat, and the corundum boat was placed in a tube furnace for high-temperature carbonization treatment: under argon atmosphere, the temperature was raised to 1200℃ at a rate of 10℃ / min, and the temperature was kept for 3h to obtain a coal-tar pitch-based composite hard carbon material.
[0076] Figure 4 The SEM image of the coal-tar pitch-based composite hard carbon material prepared in Example 3 can be seen from Figure 4 , since the content of carbon derived from dipotassium ethylenediaminetetraacetate is low, the dense structure of the material makes it difficult for sodium ions to find a storage location, and its charge and discharge capacity will be very low, far lower than that of an effectively activated sample.
[0077] The coal-tar pitch-based composite hard carbon material prepared in Example 3 was used as a negative electrode material to assemble a sodium-ion battery, and the specific assembly method was as follows: the above coal-tar pitch-based composite hard carbon material, Ketjen black and sodium carboxymethyl cellulose were mixed, ground and mixed according to a mass ratio of 8:1:1, the fine powder obtained by grinding was added to 1mL deionized water, and the slurry with suitable viscosity was continuously ground, the slurry was uniformly coated on a copper foil with a coater, and after air drying, vacuum drying (110℃, 12h) was performed, and then it was cut into a circular negative electrode sheet with a diameter of 12mm with a sheet cutting machine; the half-cell was assembled in an argon-filled glove box, metal sodium was used as the counter electrode, 1mol NaPF6 was dissolved in 1,2-dimethoxyethane as the electrolyte, and a CR2032 type button cell was assembled, and after standing for 8h, electrochemical charge and discharge test was performed. The test voltage range was 0.01V-3V, and the current density was 0.03Ag -1 , and the test results are shown in Figure 5 , the reversible specific capacity was 283.83mAhg -1 , and the initial coulombic efficiency was 89.9%.
[0078] Example 4
[0079] The same as Example 3, except that dipotassium ethylenediaminetetraacetate was replaced by an equal amount of disodium ethylenediaminetetraacetate.
[0080] The coal tar pitch-based composite hard carbon material prepared in Example 4 was used as the negative electrode material for assembling sodium-ion batteries. The specific assembly method was the same as in Example 3. After the assembled button batteries were left to stand for 8 hours, electrochemical charge-discharge tests were performed under the same conditions as in Example 3. The test results are as follows: Figure 6 As shown, the reversible specific capacity is 282.41 mAh g. -1 The initial Coulomb efficiency was 90.79%.
[0081] Example 5
[0082] S1. The raw coal tar pitch is crushed to obtain coal tar pitch powder;
[0083] S2. Place 1g of dipotassium ethylenediaminetetraacetate, 20mL of deionized water and 15mL of anhydrous ethanol in a beaker, mix them to obtain a transparent solution, add 1g of coal tar pitch powder to the above transparent solution, mix well, and then place it in a forced-air drying oven to evaporate and dry (150℃, 6h) to obtain a mixture.
[0084] S3. Place the mixture from S2 into a corundum ceramic boat, and then place the corundum ceramic boat in a tube furnace for pre-carbonization treatment: under an argon atmosphere, heat to 600℃ at a rate of 10℃ / min and hold for 2 hours to obtain a preliminary black product; place the preliminary black product in dilute hydrochloric acid and stir for 12 hours, then wash the product with deionized water until neutral, filter, and place the obtained black product in a forced-air drying oven (150℃, 3 hours) to obtain a black powder;
[0085] S4. Place the black powder from S3 into a corundum ceramic boat, and then place the corundum ceramic boat in a tube furnace for high-temperature carbonization treatment: under an argon atmosphere, heat to 1200℃ at a rate of 10℃ / min and hold for 3 hours to prepare coal tar pitch-based composite hard carbon material.
[0086] Figure 7 The image shows a SEM image of the coal tar pitch-based composite hard carbon material prepared in Example 5. Figure 7 As can be seen from the data, in this composite material, the three-dimensional nanoporous framework derived from dipotassium ethylenediaminetetraacetate is coated with coal tar sheets, forming a closed-pore-dense layer composite structure. The introduction of coal tar retains part of the graphitized layered structure during the activation process and provides a certain amount of closed pores, which not only ensures sufficient active sites and provides a channel for rapid migration of sodium ions, but also avoids side reactions and efficiency reduction caused by over-activation.
[0087] The coal pitch-based composite hard carbon material prepared in Example 5 was used as a negative electrode material to assemble a sodium ion battery. The specific assembly method was as follows: the coal pitch-based composite hard carbon material prepared in Example 5, Ketjen black and sodium carboxymethyl cellulose were mixed, ground and mixed in a mass ratio of 8:1:1, the fine powder obtained by grinding was added to 1 mL of deionized water, and the slurry with suitable viscosity was obtained by further grinding. The slurry was uniformly coated on a copper foil with a coater, and then vacuum dried (110°C, 12h) after air drying. Then, the copper foil was cut into a circular negative electrode sheet with a diameter of 12 mm using a sheet cutting machine. The half-cell was assembled in an argon-filled glove box, a metal sodium was used as a counter electrode, 1 mol NaPF6 was dissolved in 1,2-dimethoxyethane to serve as an electrolyte, and a CR2032 type button cell was assembled. After standing for 8h, electrochemical charge and discharge test was performed. The test voltage range was 0.01V-3V, and the current density was 0.03Ag -1 . The test results are shown in Figure 8 , the reversible specific capacity was 335.78mAhg -1 , and the initial coulombic efficiency was 93.2%.
[0088] Example 6
[0089] The same as Example 5, except that the di-potassium ethylenediaminetetraacetate was replaced by di-sodium ethylenediaminetetraacetate.
[0090] The coal pitch-based composite hard carbon material prepared in Example 6 was used as a negative electrode material to assemble a sodium ion battery. The specific assembly method was the same as that in Example 5. After standing for 8h, electrochemical charge and discharge test was performed on the assembled button cell, and the test conditions were the same as those in Example 5. The test results are shown in Figure 9 , the reversible specific capacity was 332.25mAhg -1 , and the initial coulombic efficiency was 93.02%.
[0091] Example 7 A method for preparing a coal pitch-based composite hard carbon material
[0092] S1. The raw coal pitch was subjected to a crushing treatment to obtain a coal pitch powder;
[0093] S2. 3g of di-potassium ethylenediaminetetraacetate, 30mL of deionized water and 20mL of anhydrous ethanol were placed in a beaker, mixed to obtain a transparent solution, 1g of coal pitch powder was added to the transparent solution, mixed uniformly, and then placed in a blast oven for evaporation and drying (150°C, 6h) to obtain a mixture;
[0094] S3. The mixture of S2 was put into a corundum boat, and the corundum boat was placed in a tube furnace for pre-carbonization treatment: under argon atmosphere, the temperature was raised to 600℃ at a rate of 10℃ / min, and the temperature was kept for 2h to obtain a preliminary black product; the preliminary black product was placed in dilute hydrochloric acid and stirred for 12h, then the product was washed to neutral with deionized water, and suction filtration was performed, and the obtained black product was placed in a blast drying oven (150℃, 3h) to obtain a black powder;
[0095] S4. The black powder of S3 was put into a corundum boat, and the corundum boat was placed in a tube furnace for high-temperature carbonization treatment: under argon atmosphere, the temperature was raised to 1200℃ at a rate of 10℃ / min, and the temperature was kept for 3h to obtain a coal-tar pitch-based composite hard carbon material.
[0096] Figure 10 The SEM image of the coal-tar pitch-based composite hard carbon material prepared in Example 7 can be seen from Figure 10 , which shows that: due to the increase of the content of dipotassium ethylenediaminetetraacetate, the coal-tar pitch carbon layer is not completely coated, the specific surface area of the composite material increases rapidly, a large number of unstable large pores or pore connectivity collapse are easily formed, which reduces the effective sodium storage active sites, resulting in a decrease in capacity.
[0097] The coal-tar pitch-based composite hard carbon material prepared in Example 7 was used as a negative electrode material to assemble a sodium-ion battery, and the specific assembly method was as follows: the coal-tar pitch-based composite hard carbon material prepared in Example 7, Ketjen black and sodium carboxymethyl cellulose were mixed, ground and mixed according to a mass ratio of 8:1:1, the fine powder obtained by grinding was added to 1mL deionized water, and the slurry with suitable viscosity was obtained by further grinding, the slurry was uniformly coated on a copper foil with a coater, and after air drying, vacuum drying (110℃, 12h) was performed, and then the copper foil was cut into a circular negative electrode sheet with a diameter of 12mm with a sheet cutting machine; the half-cell was assembled in an argon-filled glove box, metal sodium was used as the counter electrode, 1mol NaPF6 was dissolved in 1,2-dimethoxyethane to obtain an electrolyte, and a CR2032 type button cell was assembled, and after standing for 8h, electrochemical charge and discharge test was performed. The test voltage range was 0.01V-3V, and the current density was 0.03Ag -1 , and the test results are shown in Figure 11 , the reversible specific capacity was 175.17mAhg -1 , and the initial coulombic efficiency was 94.73%.
[0098] Example 8
[0099] The same as Example 7, except that dipotassium ethylenediaminetetraacetate was replaced by an equal amount of disodium ethylenediaminetetraacetate.
[0100] The coal tar pitch-based composite hard carbon material prepared in Example 7 was used as the negative electrode material for assembling sodium-ion batteries. The specific assembly method was the same as in Example 7. After the assembled button batteries were left to stand for 8 hours, electrochemical charge-discharge tests were performed under the same test conditions as in Example 7. The test results are as follows. Figure 12 As shown, the reversible specific capacity is 158.05 mAh g. -1 The initial Coulomb efficiency was 88.52%.
[0101] Comparative Example 1
[0102] The raw coal tar pitch is crushed to obtain coal tar pitch powder, which is then placed in a tube furnace for high-temperature carbonization: under an argon atmosphere, the temperature is increased to 1200℃ at a rate of 10℃ / min and held for 2 hours. After carbonization, a black product is obtained, which is the hard carbon material.
[0103] Figure 13 The image shows a SEM image of the hard carbon material prepared in Comparative Example 1. Figure 13 As can be seen, the samples obtained from the pyrolysis of coal tar pitch exhibit a typical lamellar stacking morphology and a relatively smooth surface. This material typically has a small interlayer spacing, limited sodium storage active sites, and a relatively dense microstructure, which severely restricts its sodium storage capacity and overall electrochemical performance.
[0104] The hard carbon material prepared in Comparative Example 1 was used as the negative electrode material for sodium-ion batteries. The specific assembly method is as follows: The hard carbon material prepared in Comparative Example 1, Ketjen Black (purchased from Guangdong Zhuguang New Energy Technology Co., Ltd., model Kelode ECP-600JD), and sodium carboxymethyl cellulose (purchased from Guangdong Zhuguang New Energy Technology Co., Ltd., model Kelode CMC2200) were mixed and ground in a mass ratio of 8:1:1. The resulting fine powder was added to 1 mL of deionized water, and the mixture was further ground into a slurry of suitable viscosity. The slurry was evenly coated onto copper foil using a coater, air-dried, and then vacuum-dried (110℃, 12h). It was then cut into circular negative electrode sheets with a diameter of 12 mm using a cutting machine. Half-cell assembly was performed in an argon-filled glove box, using metallic sodium as the counter electrode. 1 mol of NaPF6 was dissolved in 1,2-dimethoxyethane as the electrolyte to assemble a CR2032 type button cell. After standing for 8 hours, electrochemical charge-discharge tests were conducted. The test voltage range is 0.01V-3V, and the current density is 0.03Ag. -1 The test results are as follows Figure 14 As shown; the reversible specific capacity is 154.13 mAh g. -1 The initial Coulomb efficiency was 85.32%.
[0105] Comparative Example 2
[0106] S1. Take 3 g of ethylenediaminetetraacetic acid dipotassium or ethylenediaminetetraacetic acid disodium powder into a porcelain boat, and then place the porcelain boat in a tube furnace for pre-carbonization treatment: heat to 600 DEG C at a rate of 10 DEG C / min, and keep for 2 h to obtain a preliminary black product; place the preliminary black product in dilute hydrochloric acid, stir for 12 h, then wash the product with deionized water until neutral, and then filter under suction, and then place the obtained black product in a blast drying oven (150 DEG C, 3 h) to obtain a black powder;
[0107] S2. Place the black powder of S1 into a corundum porcelain boat, and then place the corundum porcelain boat in a tube furnace for high-temperature carbonization treatment: heat to 1200 DEG C at a rate of 10 DEG C / min under an argon atmosphere, and keep for 3 h to obtain a black product, which is a porous carbon material.
[0108] Figure 15 The SEM image of the porous carbon material prepared for Comparative Example 2 can be seen from Figure 15 that the ethylenediaminetetraacetic acid dipotassium derived carbon presents a porous structure, which usually has problems such as low mechanical strength, small tap density, and easy occurrence of irreversible side reactions in the high potential region, thereby limiting its application in batteries.
[0109] The hard carbon material prepared in Comparative Example 2 is used as a negative electrode material to assemble a sodium ion battery, and the specific assembly method is as follows: the porous carbon material prepared in Comparative Example 2, Ketjenblack (purchased from Guangdong Candlelight New Energy Technology Co., Ltd., model Ketjenblack ECP-600JD) and sodium carboxymethyl cellulose (purchased from Guangdong Candlelight New Energy Technology Co., Ltd., model Ketjenblack CMC2200) are mixed, ground and mixed according to a mass ratio of 8:1:1, the fine powder obtained by grinding is added into 1 mL of deionized water, and the slurry with suitable viscosity is obtained by further grinding, the slurry is uniformly coated on a copper foil by a coater, and then vacuum dried (110 DEG C, 12 h) after air drying, and then cut into a circular negative electrode sheet with a diameter of 12 mm by a sheet cutting machine; the half battery is assembled in an argon-filled glove box, a metal sodium is used as a counter electrode, 1 mol of NaPF6 is dissolved in 1,2-dimethoxyethane to obtain an electrolyte, and then a CR2032 type button cell is assembled, and then electrochemical charge and discharge tests are carried out after standing for 8 h. The test voltage range is 0.01 V-3 V, the current density is 0.03 Ag -1 , and the test results are shown in Figure 16 , the reversible specific capacity is 177.83 mAhg -1 , and the initial coulombic efficiency is 52%.
[0110] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements easily thought of by those skilled in the art within the technical range disclosed by the present application should be covered within the protection scope of the present application.
Claims
1. A method for preparing a coal tar pitch-based composite hard carbon material, characterized in that, Includes the following steps: Coal tar pitch, organometallic compounds and solvents are mixed and dried to obtain a mixture. After pre-carbonization treatment, the mixture is acid-washed, washed until neutral, dried and carbonized at high temperature to obtain the coal tar pitch-based composite hard carbon material.
2. The preparation method according to claim 1, characterized in that, The organometallic compound is dipotassium ethylenediaminetetraacetate or disodium ethylenediaminetetraacetate, and the solvent includes water and anhydrous ethanol.
3. The preparation method according to claim 2, characterized in that, The ratio of the amount of the organometallic compound, water and anhydrous ethanol is (0.2-3)g∶(10-30)mL∶(5-20)mL.
4. The preparation method according to claim 2, characterized in that, The mass ratio of coal tar pitch to organometallic compound is 1:(0.2-3).
5. The preparation method according to claim 4, characterized in that, The mass ratio of coal tar pitch to organometallic compound is 1:(0.2-1).
6. The preparation method according to claim 5, characterized in that, The mass ratio of coal tar pitch to organometallic compound is 1:
1.
7. The preparation method according to claim 1, characterized in that, The pre-carbonization treatment is as follows: under an inert gas atmosphere, the temperature is increased to 600°C at a rate of 10°C / min and held for 2 hours.
8. The preparation method according to claim 1, characterized in that, The high-temperature carbonization process is as follows: under an inert gas atmosphere, the temperature is increased to 1200℃ at a rate of 10℃ / min and held for 3 hours.
9. A coal tar pitch-based composite hard carbon material prepared by the preparation method according to any one of claims 1-8.
10. The application of the coal tar pitch-based composite hard carbon material according to claim 9 in the preparation of sodium-ion battery anode materials.