Preparation method of multi-element doped pitch-based hard carbon material for sodium ion battery negative electrode and battery
The asphalt-based hard carbon material prepared by multi-element doping and cross-linking technology solves the problems of specific capacity and rate performance of hard carbon materials in sodium ion batteries, achieves high capacity and high efficiency electrochemical performance, and is suitable for power batteries.
Patent Information
- Application Number
- CN202411783319.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2044-12-06
AI Technical Summary
Existing hard carbon materials have difficulty in achieving a balance among specific capacity, rate performance and first coulombic efficiency in sodium-ion batteries, and cannot meet power and energy storage requirements.
Through multi-component doping and cross-linking technology, multi-component doped asphalt-based hard carbon materials are prepared, oxygen, nitrogen and phosphorus heteroatoms are introduced to form a short-range ordered structure, inhibit the graphitization tendency, and improve the conductivity and sodium ion transmission capacity.
It achieves high specific capacity, excellent rate performance and high first coulombic efficiency, meeting the needs of power batteries.
Smart Images
Figure CN119461333B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of sodium ion batteries, and specifically relates to a preparation method and application of a multi-element doped asphalt-based hard carbon material. Background Art
[0002] Sodium-ion batteries are generally considered to be the best choice to replace lithium-ion batteries in the field of new energy because the resources of metallic sodium are more abundant and cheaper than lithium, and they have a lower decomposition potential. However, since the ion radius of Na is larger than that of Li, the migration of the click material is slow, the intercalation and deintercalation process is complicated, and the reversible capacity and rate performance are not ideal and cannot meet actual needs. The graphite negative electrode material widely used in lithium-ion batteries is not suitable for sodium-ion batteries. Na + Due to the large size of the ions, the intercalation compounds they form with carbon are thermodynamically unstable, making them difficult to embed into graphite layers. Currently, hard carbon materials are widely recognized as suitable anode materials for sodium-ion batteries and are the most promising for commercial production. Compared to soft carbon materials, which are all amorphous carbon, hard carbon materials are carbon materials that do not convert to graphite even at temperatures exceeding 3000°C. Hard carbon materials can be sourced from a wide range of sources, including biomass, fossil fuels, and polymer resins, and their preparation process is relatively simple, thus attracting considerable research attention. However, compared to traditional graphite anode materials, hard carbon materials have a short-range ordered structure and lower electrical conductivity, which affects rate performance and first coulombic efficiency. Furthermore, hard carbon materials contain numerous micropores and defects, and their complex and heterogeneous structure hinders the full capacity of the active material. Existing hard carbon materials exhibit significant voltage hysteresis during high-rate charge and discharge, resulting in a full-cell platform capacity corresponding to a voltage lower than the deposition voltage of metallic sodium. Consequently, achieving both high specific capacity and rate performance is often difficult. At high current densities, the capacity decays rapidly, failing to meet the requirements of current high-power batteries, particularly those for new energy vehicles.
[0003] In order to increase the conductivity of hard carbon materials, there are existing technologies that add nanostructured materials such as carbon nanotubes and graphene to build efficient conductive channels, but this leads to a significant increase in support costs, which loses the advantage of low cost of hard carbon materials and is difficult to commercialize. Doping is a method for effectively improving hard carbon materials. CN115849372A discloses an active hard carbon material, which is a 5-dipyridoyl chloride and 4-(4-aminophenyl)-2,6-bis(4-aminophenyl)pyridine polycondensation to obtain a pyridine-based porous polymer, high-temperature carbonization, and nitrogen doping to form active structures such as pyridine N in the carbon material, thereby improving the degree of graphitization of the carbon material and having higher conductivity and electrochemical properties. However, its process is complex, and the raw material is a polymer obtained by polycondensation of a monomer under a catalyst, and the manufacturing cost is high. CN118771353A discloses an oxygen-doped hard carbon electrode material, which comprises dissolving a pitch carbon source and a cross-linking agent in an epoxy organic solvent, adding a catalyst, and heating to obtain a mixed solution; adding an alkaline solution to the mixed solution to carry out a cross-linking reaction, and obtaining a cross-linked solid after drying; placing the cross-linked solid in a hydrogen-argon mixed atmosphere and heating to obtain a pre-treated cross-linked solid; and annealing the pre-treated cross-linked solid to obtain the oxygen-doped hard carbon electrode material.
[0004] However, the hard carbon materials provided by the above-mentioned existing technologies still cannot take into account the specific capacity, rate performance and first coulombic efficiency, and cannot meet the requirements of power and energy storage sodium ion batteries. Summary of the Invention
[0005] In order to overcome the problem that the electrochemical performance of sodium ion battery hard carbon materials in the prior art cannot meet actual requirements, especially the problem that the specific capacity, rate performance and first coulombic efficiency cannot be taken into account at the same time. The present invention proposes a preparation method and application of a multi-element doped asphalt-based hard carbon material. The present invention is achieved through the technical means of multi-element doping and cross-linking, and has high specific capacity and rate performance, high capacity retention rate at high rate current density, and high first coulombic efficiency, so as to meet the current growing demand for batteries, especially power batteries.
[0006] Specifically, the present invention achieves the above-mentioned purpose through the following technical solutions:
[0007] A method for preparing a multi-element doped pitch-based hard carbon material comprises the following steps:
[0008] (S1) asphalt and zinc salt of an organic acid are mixed and crushed, and then pre-oxidized in an oxygen-containing atmosphere to obtain pre-oxidized asphalt particles;
[0009] (S2) pre-oxidized asphalt particles, N-containing aromatic polyaldehyde, and hydroxyethylidene diphosphoric acid are uniformly mixed and reacted at elevated temperature under an inert atmosphere to obtain modified asphalt particles;
[0010] (S3) Under an inert atmosphere, the modified asphalt particles are carbonized at high temperature to obtain a multi-component doped asphalt-based hard carbon material.
[0011] Furthermore, in step (S1), the asphalt is selected from at least one of petroleum asphalt, coal asphalt, and biomass asphalt, and the softening point of the asphalt is 100-160°C; the organic acid zinc is selected from at least one of zinc gluconate, zinc tartrate, zinc citrate, and zinc malate, preferably zinc tartrate.
[0012] Furthermore, in step (S1), the amount of organic acid zinc used is 10-20 wt% of the asphalt. The crushing method is not particularly limited, as long as the asphalt is formed into microspheres of 5-20 μm, for example, ball milling can be used.
[0013] The organic zinc acid incorporated into the present invention serves multiple purposes. Firstly, the organic zinc acid is rich in oxygen atoms, which enhances oxidation efficiency and forms a richer variety of oxygen-containing functional groups during the pre-oxidation step. Furthermore, the inventors unexpectedly discovered that the inclusion of the organic zinc acid can suppress the degree of high-temperature carbonization and graphitization, resulting in a higher degree of defects and disorder in the product, which in turn increases the interlayer spacing of the resulting hard carbon material. This is likely due to the catalytic aromatization of the product produced by the pyrolysis of the organic zinc acid during the high-temperature carbonization process.
[0014] Furthermore, in step (S1), the oxygen-containing atmosphere is an atmosphere with an oxygen volume content of more than 20%, such as oxygen or air. The pre-oxidation temperature is 180-240° C., and the pre-oxidation time is 3-5 hours.
[0015] Pre-oxidation introduces oxygen defects, breaking the ordered structure of the asphalt, which can form a short-range ordered structure during the subsequent high-temperature carbonization process, inhibiting the graphitization tendency of carbon atom rearrangement at high temperature; in addition, oxygen-containing functional groups are introduced into the asphalt after pre-oxidation, which is more conducive to the subsequent cross-linking step.
[0016] Furthermore, in step (S2), the N-containing aromatic polyaldehyde is at least one of 1,3,5-tris(4-formaldehydephenyl)-2,4,6-triazine, (3,3'-bipyridine)-6,6'-dicarbaldehyde, and pyridine-2,6-dicarbaldehyde.
[0017] Furthermore, in step (S2), the mass ratio of the pre-oxidized asphalt particles, the N-containing aromatic polyaldehyde, and the hydroxyethylidene diphosphoric acid is 100:5-8:3-6. The mixing method is not particularly limited, and may include high-speed mixing or ball milling. Ball milling is preferred. The inert atmosphere is nitrogen and / or argon.
[0018] Furthermore, in step (S2), the temperature-raising reaction is to heat the temperature to 200-300°C for 2-3h. The N-containing aromatic polyaldehyde acts as a cross-linking agent on the one hand and introduces dopant N on the other hand; similarly, hydroxyethylidene diphosphonic acid acts as a cross-linking agent on the one hand and introduces dopant P on the other hand. The present invention introduces dopant oxygen in the pre-oxidation step and introduces dopant N and dopant phosphorus in step (S2) to form a multi-element doping of the hard carbon material. The multi-element doping of O, N, and P plays a synergistic role and works together to improve the electrochemical properties of the hard carbon material. Cross-linking is conducive to the transformation of long-range order into short-range ordered structure after high-temperature carbonization, and can inhibit the rearrangement of carbon during high-temperature carbonization; at the same time, the introduction of N and P also reduces the degree of order of the hard carbon material and introduces more defects.
[0019] Furthermore, in step (S3), high-temperature carbonization is carried out by heating the temperature to 800-1100°C at a heating rate of 1-3°C / min, pre-carbonizing for 1-2 hours, then heating the temperature to 1100-1600°C at a heating rate of 1-10°C / min, pre-carbonizing for 2-5 hours, cooling to room temperature, and sieving to obtain the product multi-doped asphalt-based hard carbon material.
[0020] The hard carbon material prepared by the above preparation method is modified by multi-element doping, and the active sites with Na ions are increased, which inhibits the graphitization accumulation of high-temperature carbonization, is beneficial to increase the interlayer spacing, and enhances the sodium storage capacity of the material at high rates. It has excellent electrochemical properties, high specific capacity, high first coulombic efficiency, excellent rate performance and cycle stability.
[0021] The present invention also provides a sodium ion battery comprising a positive electrode, a negative electrode, an electrolyte and a separator, wherein the negative electrode comprises the above-mentioned multinary doped asphalt-based hard carbon material.
[0022] The present invention rationally optimizes the preparation process. First, a pitch precursor and an organic zinc acid are mixed and then pre-oxidized to reduce the hydrogen content, increase the softening point, and increase the number of oxygen-containing functional groups in the precursor. N- and P-containing crosslinking agents are then added for crosslinking. The crosslinking agents exert multifunctional effects, namely crosslinking. Furthermore, N and P doping of the hard carbon material is performed. The presence of these heteroatoms can reduce the rearrangement of carbon atoms during carbonization, inhibiting the tendency to graphitization. This gives the resulting hard carbon material a short-range ordered structure, enhanced sodium storage capacity, and improved sodium ion transport capacity. The hard carbon material obtained by the preparation method of the present invention exhibits high specific capacity and first coulombic efficiency, as well as improved rate performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 is an SEM image of the hard carbon material obtained in Example 1.
[0024] Figure 2 This is a TEM image of the hard carbon material obtained in Example 1.
[0025] Figure 3 is the XRD pattern of the hard carbon material obtained in Example. DETAILED DESCRIPTION
[0026] The present invention will be further described below with reference to specific examples, but the present invention is not limited to the following examples.
[0027] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.
[0028] The petroleum asphalt used in the embodiment of the present invention has a softening point of 120°C.
[0029] Example 1
[0030] (S1) 100 parts by mass of petroleum asphalt and 10 parts by mass of zinc tartrate were mixed by ball milling at a ball-to-material ratio of 20:1, a rotation speed of 300 rpm, and a ball milling time of 2 h to obtain a spherical material with a particle size of approximately 15 μm. The ball-milled material was pre-oxidized at 200° C. in an air atmosphere for 3 h to obtain pre-oxidized asphalt particles.
[0031] (S2) 100 parts by mass of pre-oxidized asphalt particles, 5 parts by mass of 1,3,5-tris(4-formylphenyl)-2,4,6-triazine, and 5 parts by mass of hydroxyethylidene diphosphonic acid were mixed uniformly by ball milling, and the mixture was heated to 260° C. under a nitrogen atmosphere and reacted for 3 hours to obtain modified asphalt particles;
[0032] (S3) The modified asphalt particles are subjected to high-temperature carbonization under a nitrogen atmosphere. The high-temperature carbonization is first slowly heated to 1000°C at a heating rate of 3°C / min, kept warm for pre-carbonization for 1 hour, then heated to 1400°C at a heating rate of 10°C / min, kept warm for 3 hours, cooled and sieved to obtain the product multi-element doped asphalt-based hard carbon material.
[0033] Figure 1 is an SEM image of the hard carbon material obtained in Example 1. Figure 2 This is a TEM image of the hard carbon material obtained in Example 1. Figure 3 is the XRD pattern of the hard carbon material obtained in Example. Figure 3 The XRD pattern shows that the (002) interlayer spacing is 0.385 nm.
[0034] Example 2
[0035] (S1) 100 parts by mass of petroleum asphalt and 20 parts by mass of zinc gluconate were mixed by ball milling at a ball-to-material ratio of 20:1, a rotation speed of 300 rpm, and a ball milling time of 2 h to obtain a spherical material with a particle size of approximately 15 μm. The ball-milled material was pre-oxidized at 200° C. in an air atmosphere for 5 h to obtain pre-oxidized asphalt particles.
[0036] (S2) 100 parts by mass of pre-oxidized asphalt particles, 8 parts by mass of 1,3,5-tris(4-formylphenyl)-2,4,6-triazine, and 6 parts by mass of hydroxyethylidene diphosphonic acid were mixed uniformly by ball milling, and the mixture was heated to 300° C. under a nitrogen atmosphere and reacted for 2 hours to obtain modified asphalt particles;
[0037] (S3) The modified asphalt particles are subjected to high-temperature carbonization under a nitrogen atmosphere. The high-temperature carbonization is first slowly heated to 800°C at a heating rate of 3°C / min, kept warm for pre-carbonization for 2 hours, then heated to 1400°C at a heating rate of 10°C / min, kept warm for 3 hours, cooled and sieved to obtain the product multi-element doped asphalt-based hard carbon material.
[0038] Example 3
[0039] Other conditions were the same as those in Example 1, except that in step (S2), 1,3,5-tris(4-formaldehydephenyl)-2,4,6-triazine was replaced by an equal amount of (3,3'-bipyridine)-6,6'-dicarbaldehyde.
[0040] Example 4
[0041] Other conditions were the same as those in Example 1, except that in step (S2), 1,3,5-tris(4-formaldehydephenyl)-2,4,6-triazine was replaced by an equal mass of pyridine-2,6-dicarbaldehyde.
[0042] Example 5
[0043] Other conditions were the same as those in Example 1, except that in step (S3), after pre-carbonization, the temperature was raised to 1100°C at a rate of 10°C / min and kept at this temperature for 3 hours.
[0044] Example 6
[0045] Other conditions were the same as those in Example 1, except that in step (S3), after pre-carbonization, the temperature was raised to 1500°C at a rate of 10°C / min and kept at this temperature for 3 hours.
[0046] Example 7
[0047] Other conditions were the same as those in Example 1, except that in step (S3), after pre-carbonization, the temperature was raised to 1600°C at a rate of 10°C / min and kept at this temperature for 3h.
[0048] Comparative Example 1
[0049] Other conditions and operations were the same as those in Example 1, except that in step (S1), zinc tartrate was replaced by magnesium tartrate.
[0050] Comparative Example 2
[0051] Other conditions and operations were the same as those in Example 1, except that in step (S1), after the petroleum asphalt and zinc tartrate were ball-milled and mixed, the resulting material was directly subjected to step (S2), i.e., the step of heating and pre-oxidation under air in step (S1) was eliminated.
[0052] Comparative Example 3
[0053] Other conditions and operations were the same as those in Example 1, except that in step (S2), 1,3,5-tris(4-formaldehydephenyl)-2,4,6-triazine was replaced by an equal amount of terephthalaldehyde.
[0054] Comparative Example 4
[0055] Other conditions and operations were the same as those in Example 1, except that in step (S2), hydroxyethylidene diphosphate was not added.
[0056] Application Examples
[0057] The hard carbon materials prepared in the above examples and comparative examples were assembled into a sodium ion battery. Specifically, the hard carbon material, PVDF, and carbon black were added to the solvent N-methylpyrrolidone in a mass ratio of 90:7:3 to prepare a slurry. The slurry was coated on a copper foil current collector to ensure that the hard carbon material loading on the copper foil current collector was 1 mg / cm 2 , used as the negative electrode; a sodium sheet was used as the counter electrode, and a 2032 button cell was assembled in an argon-filled glove box using an EC:DMC solution in a volume ratio of 1:1 and 1 mol / L NaPF6 as the electrolyte. After assembly, the cells were left to stand at 25±2°C for 8 hours. The electrochemical performance was tested, and the results are shown in Table 1. The charge-discharge cycle voltage range was 0.01V-2.5V.
[0058] Table 1 Electrochemical performance test
[0059]
[0060]
Claims
1. A method for preparing a multi-element doped pitch-based hard carbon material for a negative electrode of a sodium ion battery, characterized in that: The following steps are involved: (S1) asphalt and a zinc salt of an organic acid are mixed and crushed, and then pre-oxidized in an oxygen-containing atmosphere to obtain pre-oxidized asphalt particles; the zinc salt of the organic acid is selected from zinc gluconate and zinc tartrate; (S2) pre-oxidized asphalt particles, an N-containing aromatic polyaldehyde, and hydroxyethylidene diphosphoric acid are uniformly mixed and reacted at elevated temperature under an inert atmosphere to obtain modified asphalt particles; the N-containing aromatic polyaldehyde is at least one of 1,3,5-tris(4-formaldehydephenyl)-2,4,6-triazine, (3,3'-bipyridine)-6,6'-dicarbaldehyde, and pyridine-2,6-dicarbaldehyde; (S3) Under an inert atmosphere, the modified asphalt particles are carbonized at high temperature to obtain a multi-component doped asphalt-based hard carbon material.
2. The preparation method according to claim 1, characterized in that In step (S1), the asphalt is selected from at least one of petroleum asphalt, coal asphalt, and biomass asphalt, and the softening point of the asphalt is 100-160°C.
3. The preparation method according to claim 1, characterized in that In step (S1), the amount of organic acid zinc used is 10-20wt% of the asphalt.
4. The preparation method according to claim 1, characterized in that In step (S1), the oxygen-containing atmosphere is an atmosphere with an oxygen volume content of more than 20%; the pre-oxidation temperature is 180-240° C., and the pre-oxidation time is 3-5 hours.
5. The preparation method according to claim 1, characterized in that In step (S1) and step (S2), the mass ratio of the pre-oxidized asphalt particles, the N-containing aromatic polyaldehyde, and the hydroxyethylidene diphosphoric acid is 100:5-8:3-6.
6. The preparation method according to claim 1, characterized in that In step (S2), the temperature is raised to 200-300° C. for 2-3 hours.
7. The preparation method according to claim 1, characterized in that In step (S3), high-temperature carbonization is carried out by heating the temperature to 800-1100°C at a heating rate of 1-3°C / min, pre-carbonizing for 1-2 hours, then heating the temperature to 1100-1600°C at a heating rate of 1-10°C / min, pre-carbonizing for 2-5 hours, cooling to room temperature, and sieving to obtain the product multi-doped asphalt-based hard carbon material.
8. A sodium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, characterized in that: The negative electrode comprises a hard carbon material prepared by the preparation method according to any one of claims 1 to 7.