Preparation method and application of oxidation crosslinking coupling fluorine-doped deoiled asphalt-based hard carbon
Through the oxidative crosslinking and fluorine doping methods, the problem of insufficient sodium ion storage capacity of deoilated asphalt in sodium ion batteries is solved, and efficient deoilated asphalt-based hard carbon materials are prepared, which improves battery performance and reduces production costs.
Patent Information
- Application Number
- CN202510453052.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-11
- Publication Date
- 2025-07-11
AI Technical Summary
The prior art is difficult to effectively utilize deoilated asphalt as an anode material, especially in sodium ion batteries. Due to its complex structure and high heteroatom content, the sodium ion storage capacity is insufficient, and direct high temperature pyrolysis leads to a high degree of graphitization, which affects electrochemical performance.
The carbon framework and surface properties of deoilated asphalt-based hard carbon are regulated by oxidative crosslinking and fluorine atom doping by liquid phase oxidative crosslinking and fluorine atom doping, a carbon structure rich in functional groups is constructed, and the layer spacing is expanded to prepare highly efficient sodium ion storage materials.
The high added value utilization of deoilated asphalt is achieved, the cost of negative electrode materials is reduced, the reversible capacity, cycle stability and rate performance of sodium ion batteries are improved, and the conductivity and structural stability of the electrode are improved.
Smart Images
Figure HDA0005354667040000011 
Figure HDA0005354667040000012 
Figure HDA0005354667040000021
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of anode materials for sodium-ion batteries, and particularly relates to a preparation method and application of an oxidized cross-linked and fluorine-doped deasphalted pitch-based hard carbon. Background Art
[0002] Due to the increasing production of heavy oil and the growing demand for light fuels, the refining of heavy oil has become increasingly important. As an effective pretreatment and purification technology for heavy oil, the solvent deasphalting process can effectively remove sulfur and nitrogen compounds, metal components, and asphaltenes from heavy oil, and provide high-quality deasphalted oil as a raw material for subsequent upgrading processes. However, the solvent deasphalting process produces by-products of deasphalted pitch, which accounts for about 30% of the raw material, containing high heteroatom (S, N, O) and metal (Ni, V, etc.) contents, high polarity, high molecular weight, and complex structures. So far, deasphalted pitch has not been fully utilized in traditional processing methods. Benefiting from its complex structure, high heteroatom and metal contents, deasphalted pitch is suitable as a high-quality carbon source for the preparation of amorphous carbon, especially hard carbon materials, to achieve its high-value utilization.
[0003] With the growing global demand for electrochemical energy storage technologies, energy storage technologies such as advanced ion batteries have been developed. Benefiting from the advantages of abundant sodium resources, low cost, and wide distribution, sodium-ion batteries have received considerable attention in recent years as the next-generation storage technology. Nowadays, the main challenge faced by sodium-ion batteries is the development of anode materials. Thermodynamically, the interaction force between sodium ions and graphite layers is insufficient to form a stable intercalation compound, and graphite cannot be directly used as the anode material for sodium-ion batteries. Hard carbon materials can store more sodium ions and improve the battery capacity due to their higher degree of disorder, larger interlayer distance, and abundant nanopores and defects.
[0004] Due to its high carbon content and low cost, deoiled asphalt is a potential raw material for synthesizing hard carbon materials. Preparing hard carbon materials using deoiled asphalt as the carbon precursor results in an appropriate degree of defects and a large interlayer distance, enabling high-capacity sodium storage. However, due to the rich hydrogen atom content and strong π-π interactions in planar aromatic molecules, the carbon materials prepared by direct high-temperature pyrolysis exhibit a high degree of graphitization, which is not conducive to sodium ion storage. The pre-oxidation strategy is an effective strategy for constructing asphalt-derived hard carbon materials. It can introduce stable cross-linked structures to inhibit the melting and rearrangement of the carbon skeleton during high-temperature carbonization, thereby expanding the interlayer spacing and constructing a highly disordered structure. In addition, heteroatom doping is one of the most direct and effective methods for functionalizing hard carbon. The heteroatoms exist in the form of surface functional groups, which can be used as nucleation / anchoring sites for electrolyte adsorption / desorption and as active sites for electrochemical oxidation-reduction reactions, significantly improving the sodium storage capacity. Another part of the heteroatoms occupies the carbon sites in the lattice, which can not only expand the interlayer spacing of graphite microcrystals but also adjust the electronic structure of carbon, thereby enhancing the diffusion kinetics. These factors can effectively enhance the electrochemical performance of hard carbon, including specific capacity, cycle stability, and rate performance. Summary of the Invention
[0005] The object of the present invention is to provide a preparation method for oxidized cross-linked and fluorine-doped deoiled asphalt-based hard carbon. In the present invention, deoiled asphalt is used as the hard carbon precursor, and the carbon skeleton and surface properties are regulated by liquid-phase oxidized cross-linking combined with fluorine atom doping to prepare deoiled asphalt-based hard carbon with a high carbon yield, low cost, and high sodium storage capacity.
[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:
[0007] The present invention provides a preparation method for oxidized cross-linked and fluorine-doped deoiled asphalt-based hard carbon, comprising the following steps:
[0008] (1) Pour deoiled asphalt into a flask, heat it up and stir it while passing oxygen, and grind it after cooling to obtain particle 1;
[0009] (2) Separate the insoluble matter in particle 1 with n-heptane to obtain particle 2;
[0010] (3) Mix particle 2 with absolute ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in proportion, grind them, and then place them in a hydrothermal autoclave for low-temperature pre-carbonization to obtain particle 3;
[0011] (4) Mix particle 3 with a nitric acid solution, stir it, and obtain particle 4 after filtration, washing, and drying;
[0012] (5) Transfer particle 4 to a tube furnace for carbonization to obtain particle 5.
[0013] Further, the heating conditions in step (1) are to keep the temperature at 140 - 180 °C for 4 h and then at 300 - 315 °C for 8 h.
[0014] Further, the softening point range of the particle 2 in step (2) is 180 °C - 250 °C.
[0015] Further, the mass ratio of the particle 2, absolute ethanol, and poly(vinylidene fluoride - co - hexafluoropropylene) in step (3) is 4.0 - 8.0:1.2:1.0, preferably 5.0:1.2:1.0.
[0016] Further, the concentration of the nitric acid solution in step (4) is 40% - 50%.
[0017] Further, the carbonization temperature in step (5) is 1100 - 1300 °C, the heat preservation time is 2 h, the heating rate is 3 - 5 °C / min, and the protective atmosphere is argon.
[0018] The oxidized cross - linked coupled fluorine - doped deasphalted pitch - based hard carbon can be prepared by using the above method.
[0019] The present invention uses the above - mentioned oxidized cross - linked coupled fluorine - doped deasphalted pitch - based hard carbon to prepare electrode sheets and assemble them into a sodium - ion battery.
[0020] The technical effects achieved by the present invention are as follows:
[0021] 1. For the oxidized cross - linked coupled fluorine - doped deasphalted pitch - based hard carbon of the present invention, the deasphalted pitch as the carbon precursor is a by - product of the solvent deasphalting process, and its output accounts for 30% of the raw materials. It is cheap and abundant. This not only realizes the high - value utilization of deasphalted pitch but also reduces the production cost of the negative electrode material, meets the requirements of the country's vigorous development of green energy new materials, promotes the coordinated development of the solvent deasphalting production chain and the hard carbon industrial chain, and improves the economic benefits of industrial production.
[0022] 2. For the oxidized cross - linked coupled fluorine - doped deasphalted pitch - based hard carbon of the present invention, through oxidation cross - linking, an aromatic ring and aliphatic ring carbon skeleton rich in functional groups such as carboxyl, hydroxyl, and carbonyl are constructed, and fluorine atom doping is coupled to regulate the microcrystalline orientation of the carbon skeleton, providing reversible storage sites and a large interlayer spacing for sodium - ion storage, and improving the reversible capacity, cycle stability, and rate performance of the negative electrode material. At the same time, after being modified by nitric acid, the surface of the hard carbon changes from hydrophobic to hydrophilic, enabling sufficient electrolyte wetting, fast conductivity through the electrode, shortening the carrier transport path, and structural stability. Description of the Drawings
[0023] Figure 1 It is the SEM image of an oxidized cross - linked coupled fluorine - doped deasphalted pitch - based hard carbon prepared in Example 1 of the present invention;
[0024] Figure 2 XRD pattern of an oxidized crosslinked coupled fluorine-doped deoiled asphalt-based hard carbon prepared in Example 1 of the present invention;
[0025] Figure 3 Raman pattern of an oxidized crosslinked coupled fluorine-doped deoiled asphalt-based hard carbon prepared in Example 1 of the present invention;
[0026] Figure 4 Galvanostatic charge-discharge curve of an oxidized crosslinked coupled fluorine-doped deoiled asphalt-based hard carbon prepared in Example 1 of the present invention at a current density of 100 mA·g -1 -1. Detailed implementation manners
[0027] The present invention will be further described in detail below in conjunction with embodiments, but the implementation manners of the present invention are not limited thereto. For those not specified in the embodiments in terms of specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For raw materials not specified in terms of manufacturers, they are all conventional products that can be obtained through commercial purchase.
[0028] Example 1:
[0029] The preparation method of an oxidized crosslinked coupled fluorine-doped deoiled asphalt-based hard carbon in this example is as follows:
[0030] (1) Pour deoiled asphalt into a flask, stir and heat it to 150 °C while passing oxygen, keep it warm for 4 h, then raise the temperature to 310 °C and keep it warm for 8 h. After cooling, grind it to obtain Particle 1;
[0031] (2) Add Particle 1 to n-heptane, stir well and separate the insoluble matter to obtain Particle 2 with a softening point of 200 °C;
[0032] (3) Mix Particle 2 with absolute ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in a ratio of 5.0:1.2:1.0, grind them, and then place them in a hydrothermal autoclave for low-temperature pre-carbonization at 180 °C for 10 h to obtain Particle 3;
[0033] (4) Mix Particle 3 with a nitric acid solution at a concentration of 50% at 25 °C, stir for 18 h, filter, wash, and dry to obtain Particle 4;
[0034] (5) Transfer Particle 4 to a tubular furnace, introduce argon as a protective atmosphere, heat it at a heating rate of 5 °C / min to 1300 °C, keep it warm for 2 h, and obtain Particle 5 after natural cooling;
[0035] (6) Fabrication of the electrode sheet. Weigh 5 parts of particles, carbon black, and polyvinylidene fluoride according to a mass ratio of 80:10:10 and place them in a mortar for grinding until uniform. Add an appropriate amount of N-methylpyrrolidone solvent, stir evenly to obtain a slurry, coat it evenly on the copper foil, dry it in a vacuum drying oven at 120 °C for 12 h, and cut it into 12 mm circular negative electrode sheets for standby.
[0036] (7) The coin cell assembly is carried out in a double-glove box filled with an argon atmosphere (H2O, O2 < 0.01 ppm). The prepared hard carbon material electrode sheet is used as the negative electrode sheet, 1 M NaClO4 (volume ratio of EC / DEC = 1:1) is used as the electrolyte, and a sodium metal sheet is used as the counter electrode to assemble a CR2032 coin sodium-ion battery.
[0037] (8) The assembled 2032 coin cells are subjected to charge-discharge tests on a constant current test system within a voltage range of 0.005 - 3.5 V.
[0038] Figure 1 This is the SEM image of a kind of oxidized cross-linked and fluorine-doped deoiled asphalt-based hard carbon prepared in Example 1 of the present invention; as can be seen from the figure, the prepared deoiled asphalt-based hard carbon has an amorphous structure, and the hard carbon particle size is about 10 - 15 μm. Figure 2 This is the XRD pattern of a kind of oxidized cross-linked and fluorine-doped deoiled asphalt-based hard carbon prepared in Example 1 of the present invention; two diffraction peaks are shown near 2θ = 24° and 43°, representing the (002) and (100) crystal planes of the hard carbon respectively. The peak near 24° is highly disordered amorphous carbon, proving the formation of graphite domains similar to graphite in the hard carbon, with an interlayer spacing of 0.379 nm. The appropriate interlayer spacing is beneficial for sodium ion intercalation. Figure 3 This is the Raman pattern of a kind of oxidized cross-linked and fluorine-doped deoiled asphalt-based hard carbon prepared in Example 1 of the present invention; there are two obvious peaks at 1341 cm -1 and 1594 cm -1 respectively, corresponding to the D peak originating from the vibration of disordered carbon atoms at the edge of graphite sheets or a defective graphite structure and the G peak formed by strong π-π interactions to form a regular graphite structure. The peak intensity ratio I D / I G is 1.98, which is used to measure the degree of disorder of the hard carbon material. Figure 4 This is the constant current charge-discharge curve of a kind of oxidized cross-linked and fluorine-doped deoiled asphalt-based hard carbon prepared in Example 1 of the present invention at a current density of 100 mA·g -1 ; at a current density of 100 mA·g -1 , its first-cycle Coulombic efficiency is 67.45%, and the specific capacity is 254.6 mAh·g -1 .
[0039] Example 2:
[0040] The preparation method of the oxidized cross-linked and fluorine-doped deoiled asphalt-based hard carbon in this embodiment is as follows:
[0041] (1) Pour the deoiled asphalt into a flask, stir and heat it to 140 °C while passing oxygen, then keep it warm for 4 h. Subsequently, raise the temperature to 315 °C and keep it warm for 8 h. After cooling, grind it to obtain Particle 1;
[0042] (2) Add Particle 1 to n-heptane, stir well, and separate the insoluble matter to obtain Particle 2 with a softening point of 180 °C;
[0043] (3) Mix Particle 2 with absolute ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in a ratio of 4.0:1.2:1.0, grind them, and then place them in a hydrothermal autoclave for low-temperature pre-carbonization at 190 °C for 8 h to obtain Particle 3;
[0044] (4) Mix Particle 3 with a nitric acid solution at a concentration of 50% at 20 °C and stir for 24 h. After filtration, washing, and drying, obtain Particle 4;
[0045] (5) Transfer Particle 4 to a tube furnace, introduce argon as a protective atmosphere, heat it at a heating rate of 5 °C / min to 1300 °C, and keep it warm for 2 h. After natural cooling, obtain Particle 5;
[0046] (6) The application method and performance test of the deoiled asphalt-based hard carbon in a CR2032 coin-type sodium-ion battery. Assemble the battery in the same way as in Example 1 and conduct charge-discharge performance tests.
[0047] Example 3:
[0048] The preparation method of the oxidized cross-linked and fluorine-doped deoiled asphalt-based hard carbon in this embodiment is as follows:
[0049] (1) Pour the deoiled asphalt into a flask, stir and heat it to 180 °C while passing oxygen, then keep it warm for 4 h. Subsequently, raise the temperature to 300 °C and keep it warm for 8 h. After cooling, grind it to obtain Particle 1;
[0050] (2) Add Particle 1 to n-heptane, stir well, and separate the insoluble matter to obtain Particle 2 with a softening point of 250 °C;
[0051] (3) Mix Particle 2 with absolute ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in a ratio of 8.0:1.2:1.0, grind them, and then place them in a hydrothermal autoclave for low-temperature pre-carbonization at 170 °C for 10 h to obtain Particle 3;
[0052] (4) Mix Particle 3 with a nitric acid solution at a concentration of 40% at 30 °C and stir for 22 h. After filtration, washing, and drying, obtain Particle 4;
[0053] (5) Particle 4 was transferred to a tube furnace, argon gas was introduced as a protective atmosphere, the temperature was increased to 1100°C at a heating rate of 5°C / min, and then kept at this temperature for 2 h. After natural cooling, particle 5 was obtained;
[0054] (6) Application method and performance test of deoiled asphalt-based hard carbon in CR2032 button-type sodium ion battery: The battery was assembled in the same manner as in Example 1 and the charge and discharge performance test was performed.
[0055] Embodiment 4:
[0056] The preparation method of an oxidative cross-linked coupled fluorine-doped de-oiled asphalt-based hard carbon in this embodiment is as follows:
[0057] (1) Pour the deoiled asphalt into a flask, stir and heat to 185°C, then keep the temperature for 4 hours, then increase the temperature to 305°C and keep the temperature for 8 hours, and grind after cooling to obtain particle 1;
[0058] (2) Particle 1 was added to n-heptane and stirred thoroughly, and then the insoluble matter was separated to obtain particle 2 with a softening point of 210°C;
[0059] (3) Particle 2 was mixed with anhydrous ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in a ratio of 6.5:1.2:1.0, ground, and then placed in a hydrothermal autoclave for low-temperature pre-carbonization at 170°C for 10 hours to obtain particle 3;
[0060] (4) Particle 3 was mixed with a 43% nitric acid solution at 30° C. and stirred for 20 h, and then filtered, washed, and dried to obtain particle 4;
[0061] (5) Particle 4 was transferred to a tube furnace, argon gas was introduced as a protective atmosphere, the temperature was increased to 1100°C at a heating rate of 3°C / min, and then kept at this temperature for 2 h. After natural cooling, particle 5 was obtained;
[0062] (6) Application method and performance test of deoiled asphalt-based hard carbon in CR2032 button-type sodium ion battery: The battery was assembled in the same manner as in Example 1 and the charge and discharge performance test was performed.
[0063] Embodiment 5:
[0064] The preparation method of an oxidative cross-linked coupled fluorine-doped de-oiled asphalt-based hard carbon in this embodiment is as follows:
[0065] (1) Pour the deoiled asphalt into a flask, stir and heat to 155°C, then keep the temperature for 4 hours, then increase the temperature to 315°C and keep the temperature for 8 hours, and grind after cooling to obtain particle 1;
[0066] (2) Particle 1 was added to n-heptane and stirred thoroughly, and then the insoluble matter was separated to obtain particle 2 having a softening point of 195°C;
[0067] (3) Particle 2 was mixed with anhydrous ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in a ratio of 5.5:1.2:1.0, ground, and then placed in a hydrothermal autoclave for low-temperature pre-carbonization at 170°C for 10 hours to obtain particle 3;
[0068] (4) Particle 3 was mixed with a 47% nitric acid solution at 25° C. and stirred for 19 h, and then filtered, washed, and dried to obtain particle 4;
[0069] (5) Particle 4 was transferred to a tube furnace, argon gas was introduced as a protective atmosphere, the temperature was increased to 1200°C at a heating rate of 3°C / min, and then kept at this temperature for 2 h. After natural cooling, particle 5 was obtained;
[0070] (6) Application method and performance test of deoiled asphalt-based hard carbon in CR2032 button-type sodium ion battery: The battery was assembled in the same manner as in Example 1 and the charge and discharge performance test was performed.
[0071] Embodiment 6:
[0072] The preparation method of an oxidative cross-linked coupled fluorine-doped de-oiled asphalt-based hard carbon in this embodiment is as follows:
[0073] (1) Pour the deoiled asphalt into a flask, stir and heat to 145°C, then keep the temperature for 4 hours, then increase the temperature to 305°C and keep the temperature for 8 hours, and grind after cooling to obtain particle 1;
[0074] (2) adding particle 1 to n-heptane, stirring thoroughly, and separating the insoluble matter to obtain particle 2 having a softening point of 180° C.;
[0075] (3) Particle 2 was mixed with anhydrous ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in a ratio of 4.5:1.2:1.0, ground, and then placed in a hydrothermal autoclave for low-temperature pre-carbonization at 170°C for 8 hours to obtain particle 3;
[0076] (4) Particle 3 was mixed with a 43% nitric acid solution at 30° C. and stirred for 24 h, and then filtered, washed, and dried to obtain particle 4;
[0077] (5) Particle 4 was transferred to a tube furnace, argon gas was introduced as a protective atmosphere, the temperature was increased to 1300°C at a heating rate of 3°C / min, and then kept at this temperature for 2 h. After natural cooling, particle 5 was obtained;
[0078] (6) Application method and performance test of deoiled asphalt-based hard carbon in CR2032 button-type sodium ion battery: The battery was assembled in the same manner as in Example 1 and the charge and discharge performance test was performed.
[0079] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.
Claims
1. A preparation method of an oxidation cross-linked and coupled fluorine-doped deoiled asphalt-based hard carbon, characterized in that, It includes the following steps: (1) Pour the deoiled asphalt into a flask, heat it up while stirring under oxygen, and grind it after cooling to obtain Particle 1; (2) Separate the insoluble matter in Particle 1 with n-heptane to obtain Particle 2; (3) Mix Particle 2 with absolute ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in proportion, grind them, and then place them in a hydrothermal autoclave for low-temperature pre-carbonization to obtain Particle 3; (4) Mix Particle 3 with a nitric acid solution and stir. After filtration, washing, and drying, obtain Particle 4; (5) Transfer Particle 4 to a tubular furnace for carbonization to obtain Particle 5.
2. The preparation method of an oxidation cross-linked and coupled fluorine-doped deoiled asphalt-based hard carbon according to claim 1, characterized in that, The heating conditions in step (1) are to keep the temperature at 140°C - 180°C for 4 h and at 300°C - 315°C for 8 h.
3. The preparation method of an oxidation cross-linked coupled fluorine-doped deoiled asphalt-based hard carbon according to claim 1, characterized in that, The softening point range of Particle 2 in step (2) is 180°C - 250°C.
4. The preparation method of an oxidation cross-linked coupled fluorine-doped deoiled asphalt-based hard carbon according to claim 1, wherein, The mass ratio of Particle 2 to absolute ethanol and poly(vinylidene fluoride-co-hexafluoropropylene) in step (3) is 4.0 - 8.0:1.2:1.
0.
5. The preparation method of an oxidized cross-linked coupled fluorine-doped deoiled asphalt-based hard carbon according to claim 1, characterized in that, The concentration of the nitric acid solution in step (4) is 40% - 50%.
6. The preparation method of an oxidation cross-linked and coupled fluorine-doped deoiled asphalt-based hard carbon according to claim 1, characterized in that, The carbonization temperature in step (5) is 1100 - 1300°C, the holding time is 2 h, the heating rate is 3 - 5°C / min, and the protective atmosphere is argon.
7. A deoiled asphalt-based hard carbon prepared by the preparation method according to any one of claims 1 - 6.
8. An application of the deoiled asphalt-based hard carbon according to claim 7 in the preparation of sodium-ion batteries.