Method for preparing hard carbon material from ethylene tar
By optimizing the processing technology of ethylene tar and utilizing steps of heating extraction, cross-linking, and carbonization, a hard carbon material with high sodium storage capacity and excellent electrochemical performance was prepared. This solved the problems of low utilization efficiency of ethylene tar resources and insufficient battery performance in the existing technology, and enabled the application of hard carbon materials in sodium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-14
- Publication Date
- 2026-04-14
AI Technical Summary
Existing ethylene tar processing technologies are complex, leading to the direct carbonization of ethylene tar into soft carbon with a high degree of graphitization. This makes it impossible to optimize the electrochemical performance of sodium-ion batteries, and existing methods are difficult to effectively utilize the resource advantages of ethylene tar.
By performing pretreatment through heating and extraction under an inert atmosphere, a thermal polycondensation and crosslinking reaction is carried out by mixing a crosslinking agent and a catalyst. Subsequently, curing and pre-oxidation are performed under a mixture of oxygen and inert gas, and finally carbonization is carried out under an inert atmosphere to optimize the molecular arrangement and structure of ethylene tar and form a hard carbon material.
The prepared hard carbon material has a higher sodium storage capacity and excellent electrochemical performance. It also exhibits excellent cycling performance, with an initial charge specific capacity of up to 300 mAh g⁻¹ and a capacity retention rate of up to 95.5% after 100 cycles.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery anode material technology, specifically relating to a method for preparing hard carbon anode material from ethylene tar. Background Technology
[0002] Compared to lithium-ion batteries, sodium-ion batteries have the advantages of abundant resources, low cost, and high safety. These advantages are what make sodium-ion batteries the most promising energy storage technology for large-scale application in the energy storage market.
[0003] For sodium-ion batteries, developing low-cost, high-performance electrode materials is particularly important, especially anode materials, as they directly affect many electrochemical performance indicators, including energy density, power density, and cycle performance. Among numerous anode materials, hard carbon materials have attracted much attention due to their unique sodium storage structure, such as vortex-like microcrystalline structures, graphite layers with larger interlayer spacing, and abundant pore structures. In addition, hard carbon raw materials are abundant, low in cost, and simple to prepare, all of which indicate that hard carbon materials are a promising anode material choice for sodium-ion batteries with good commercial prospects.
[0004] Ethylene tar, as a precursor for hard carbon production, boasts advantages such as low cost, abundant resources, low ash content, low impurity content, and high char yield. Furthermore, given the increasing annual production of ethylene tar in my country, efficient utilization and full exploitation of its intrinsic value are inevitable trends. Therefore, the rational use of ethylene tar to produce hard carbon is a correct decision in response to the national call. However, current ethylene tar processing technologies are complex, and ethylene tar's main components are polycyclic aromatic hydrocarbons with a high hydrogen-to-carbon ratio. Direct carbonization easily produces soft carbon with a high degree of graphitization, which cannot optimize the electrochemical performance of sodium-ion batteries.
[0005] Given its enormous commercial value and strong policy support, the process of producing hard carbon from ethylene tar urgently needs optimization and improvement. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing hard carbon materials from ethylene tar, which makes the molecular arrangement of ethylene tar more disordered during the carbonization process into hard carbon materials, thereby constructing more defects and microporous structures, so that the material can contribute higher sodium storage capacity when applied in sodium-ion batteries.
[0007] To achieve the above objectives, the present invention provides a method for preparing hard carbon materials from ethylene tar, comprising:
[0008] S1, Ethylene tar is pretreated by heating and extraction under an inert atmosphere to obtain light and heavy components;
[0009] S2, the light component is mixed with a crosslinking agent and a catalyst, and a thermal polycondensation crosslinking reaction is carried out under an inert atmosphere to obtain a preliminary crosslinking product;
[0010] S3, the preliminary cross-linked product is cured and pre-oxidized in a mixture of oxygen and inert gas to obtain a hard carbon precursor;
[0011] S4, under an inert atmosphere, the hard carbon precursor is carbonized to obtain hard carbon material.
[0012] The method for preparing hard carbon materials from ethylene tar according to the present invention includes a heating extraction temperature of 300–340°C and a extraction time of 2–5 hours in step S1. Extraction at this temperature allows light aromatic hydrocarbons containing 2–3 rings to enter the light components to the greatest extent possible, thus better adjusting the hybrid carbon content structure in the raw material.
[0013] In the method for preparing hard carbon materials from ethylene tar according to the present invention, in step S2, the mass ratio of crosslinking agent to light component is 1:5-10, and the mass ratio of catalyst to light component is 1:10-20. Crosslinking under these conditions can maximize the degree of crosslinking of the crosslinking product.
[0014] In the method for preparing hard carbon materials from ethylene tar according to the present invention, the temperature of the thermal polycondensation crosslinking reaction in step S2 is 120-160°C, and the crosslinking time is 12-17 h.
[0015] In the method for preparing hard carbon materials from ethylene tar according to the present invention, in step S3, the inert gas content in the mixed gas is 90%–95% vol%, the oxygen content is 5%–10% vol%, and the gas flow rate is 800–1200 sscm. The 90%–95% nitrogen content ensures that the initial crosslinking product is protected by an inert atmosphere during the curing process, while the 5%–10% oxygen content allows trace amounts of oxygen atoms to be introduced into the crosslinking product during curing. This oxygen content ensures both the safety of the reaction and the appropriate insertion of oxygen atoms.
[0016] In the method for preparing hard carbon materials from ethylene tar according to the present invention, in step S3, the curing and pre-oxidation temperature is 280-320°C and the time is 2-4 hours.
[0017] In the method for preparing hard carbon materials from ethylene tar according to the present invention, in step S4, the carbonization temperature is 1100-1500℃, the heating rate is 2-5℃ / min, and the holding time is 2-6h.
[0018] In the method for preparing hard carbon materials from ethylene tar according to the present invention, the inert gas in steps S1 and S2 is nitrogen, and the gas flow rate is 800-1200 sscm; the heating extraction and thermal polycondensation processes are carried out under physical stirring conditions, and the stirring speed is 120-160 rpm.
[0019] In the method for preparing hard carbon materials from ethylene tar according to the present invention, the crosslinking agent in step S2 is paraformaldehyde and / or terephthalic acid, and the catalyst is p-toluenesulfonic acid and / or concentrated sulfuric acid.
[0020] In the method for preparing hard carbon materials from ethylene tar according to the present invention, the inert gas in step S3 is nitrogen; the curing and pre-oxidation processes are carried out under physical stirring conditions, with a stirring speed of 120-160 rpm; the inert gas in step S4 is argon, with a gas flow rate of 60-100 sscm.
[0021] Beneficial effects of this invention:
[0022] This invention utilizes simple extraction and cross-linking techniques to retain the high conductivity of ethylene tar-derived carbon materials while successfully introducing abundant sodium storage structures. The resulting hard carbon material exhibits excellent electrochemical performance in sodium-ion batteries.
[0023] This invention utilizes the light components in ethylene tar to improve the performance of raw materials. 2 and sp 3 The hybrid structure ratio was optimized to enhance sp. 3 The structure hinders the orderly rearrangement of carbon layers; at the same time, selecting a suitable crosslinking agent can also help to further optimize sp. 2 and sp 3 By adjusting the hybrid structure ratio, thereby introducing more defects and micropores to create sodium storage structures, the resulting hard carbon material can contribute up to 300 mAh g⁻¹. -1 High reversible specific capacity (first charge specific capacity); through initial cross-linking and subsequent deep cross-linking, the molecular structure develops into a robust three-dimensional cross-linked network, which greatly improves the stability of the carbon skeleton of the material, giving hard carbon materials excellent cycling performance at 50 mA g. -1 The capacity retention rate can reach up to 95.5% after 100 cycles at the specified current density. Attached Figure Description
[0024] Figure 1 The XRD diagrams for the products described in Example 1 and Comparative Example 1 are shown below;
[0025] Figure 2 Here is a SEM image of the product obtained in Example 1;
[0026] Figure 3a TEM image of the product obtained in Example 1;
[0027] Figure 3b TEM image of the product obtained in Comparative Example 1;
[0028] Figure 4 The BET graphs are for Example 1 and Comparative Example 1. Detailed Implementation
[0029] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.
[0030] Example 1
[0031] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0032] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0033] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0034] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0035] Comparative Example 1
[0036] Add 200g of ethylene tar raw material to a 500ml three-necked flask, and add 40g of paraformaldehyde and 20g of p-toluenesulfonic acid. Mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, keep nitrogen gas flowing through at a gas velocity of 1000sscm.
[0037] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0038] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0039] Figure 1 The XRD patterns of the hard carbon samples obtained in Example 1 and Comparative Example 1 are shown in the figure. The (002) peak of the hard carbon material described in Example 1 is significantly shifted to the left, and the interlayer spacing is larger than that in Comparative Example 1. In addition, the XRD peaks shown in Example 1 are less sharp, which also proves that it has more amorphous structures.
[0040] Figure 2 The image shows the SEM characterization of the hard carbon material prepared in Example 1. The material is in block form with an average particle size of 3–4 μm.
[0041] Figure 3a and Figure 3b The figures show TEM characterization images of the hard carbon samples obtained in Example 1 and Comparative Example 1, respectively. As shown in the figure, Example 1 has obvious graphite-like domains and pore structures, while Comparative Example 1 is basically composed of orderly arranged graphite layers with high degree of order.
[0042] Figure 4 The BET characterization diagrams of the hard carbon samples obtained in Example 1 and Comparative Example 1 are shown in the figure. The pore size of the materials is concentrated at around 1.3 nm, but it can be seen from the figure that Example 1 has more pore structures.
[0043] Example 2
[0044] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 300℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 2h. At the same time, collect the extracted light components through a condenser.
[0045] Take 200g of the light component below 300℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0046] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0047] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0048] Example 3
[0049] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 340℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 5h. At the same time, collect the extracted light components through a condenser.
[0050] Take 200g of the light component below 340℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0051] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0052] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0053] Example 4
[0054] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0055] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take another 20g of trioxymethylene and 10g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0056] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0057] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0058] Example 5
[0059] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0060] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take another 40g of terephthalic acid and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0061] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0062] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0063] Example 6
[0064] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0065] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of paraformaldehyde and 20g of concentrated sulfuric acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, keep nitrogen gas flowing through at a gas velocity of 1000sscm.
[0066] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0067] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0068] Example 7
[0069] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0070] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 120℃ and perform constant temperature crosslinking for 12h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0071] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 120℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinking product.
[0072] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0073] Example 8
[0074] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0075] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 160℃ and perform constant temperature crosslinking for 17h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0076] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 160℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinking product.
[0077] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0078] Comparative Example 2
[0079] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0080] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0081] After the initial crosslinking is completed, the temperature is further increased from 140℃ to 300℃ and held at that temperature for 3 hours before being naturally cooled to room temperature to obtain the deeply crosslinked product.
[0082] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0083] Example 9
[0084] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0085] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 12h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0086] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 10%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinking product.
[0087] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0088] Example 10
[0089] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0090] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 17h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0091] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 280℃, and after being kept at the temperature for 2 hours, it is naturally cooled to room temperature to obtain the deep crosslinking product.
[0092] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0093] Example 11
[0094] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0095] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0096] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 320℃, and after being kept at the temperature for 4 hours, it is naturally cooled to room temperature to obtain the deep crosslinking product.
[0097] The above crosslinked product was ground and pulverized in an agate mortar. 2g of the pulverized sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 4 hours to obtain the final hard carbon sample.
[0098] Example 12
[0099] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0100] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0101] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0102] The above crosslinked product was ground and pulverized in an agate mortar. 2g of the pulverized sample was placed in a corundum crucible and heated to 1100℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 6 hours to obtain the final hard carbon sample.
[0103] Example 13
[0104] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0105] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, nitrogen gas is continuously introduced at a gas velocity of 1000sscm.
[0106] After the initial crosslinking is completed, the nitrogen gas is replaced with a nitrogen-oxygen mixture (oxygen content is 5%), and the gas flow rate remains unchanged; the physical stirrer is also in the same state as above; at the same time, the temperature is increased from 140℃ to 300℃, and after being kept at the temperature for 3 hours, it is naturally cooled to room temperature to obtain the deep crosslinked product.
[0107] The cross-linked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1500℃ in a tube furnace under an argon atmosphere at a heating rate of 2℃ / min for 2h to obtain the final hard carbon sample.
[0108] Comparative Example 3
[0109] Add 500g of ethylene tar to a 500ml three-necked flask, adjust the stirrer speed to 140rpm to ensure uniform heating during the subsequent heating process, and then heat to 320℃ under a nitrogen gas velocity of 1000sscm and keep the temperature constant for 3h. At the same time, collect the extracted light components through a condenser.
[0110] Take 200g of the light component below 320℃ and add it to a 500ml three-necked flask. Take 40g of trioxymethylene and 20g of p-toluenesulfonic acid and mix them evenly with the light component at a stirring speed of 140rpm. Use a heating mantle to raise the temperature to 140℃ and perform constant temperature crosslinking for 14h. During the crosslinking process, keep nitrogen gas flowing through at a gas velocity of 1000sscm. After the crosslinking is completed, let it cool naturally to room temperature to obtain the hard carbon precursor.
[0111] The above crosslinked product was ground into powder in an agate mortar. 2g of the powdered sample was placed in a corundum crucible and heated to 1300℃ in a tube furnace under an argon atmosphere at a heating rate of 5℃ / min for 2 hours to obtain the final hard carbon sample.
[0112] The hard carbon materials prepared in Examples 1-13 and Comparative Examples 1-3 were used as anode materials in sodium-ion batteries to assemble sodium-ion batteries and electrochemical tests were performed.
[0113] (1) Hard carbon material, conductive carbon black and polyvinylidene fluoride are mixed in a mass ratio of 90:5:5. N-methylpyrrolidone is used as solvent. After stirring for 10 hours, a uniform slurry is obtained. The slurry is uniformly coated on the carbon-coated aluminum foil current collector and dried in a forced-air drying oven at 60°C for 12 hours. The dried electrode sheet is punched, and the flat and smooth part is selected as the electrode sheet. The material is weighed and the mass of the active material is calculated.
[0114] (2) Using sodium sheet as reference electrode, button cell batteries were assembled under conditions where the water and oxygen content were both less than 0.01 ppm. The electrolyte was prepared using 1.0 mol / L sodium hexafluorophosphate as solute and ethylene carbonate (EC) and dimethyl carbonate (DEC) as solvents, with a volume ratio of ethylene carbonate (EC) to dimethyl carbonate (DEC) of 1:1. Fluorinated ethylene carbonate (FEC) was added to the electrolyte as an additive at a mass of 5% of the total electrolyte. The assembled batteries were sealed using a button cell sealing machine.
[0115] (3) The button batteries prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to their first charge-discharge test using a Blue Electric test system. The voltage window was 0.001-3V and the current density was 30mA g. -1 In addition, the prepared button cells were subjected to constant current cycling tests with a voltage window of 0.001–3V and a current density of 50 mAg. -1 The number of cycles was fixed at 100, and the specific electrochemical performance results are shown in the table below:
[0116]
[0117]
[0118] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.
Claims
1. A method for preparing hard carbon materials from ethylene tar, characterized in that, include: S1, Ethylene tar is pretreated by heating and extraction under an inert atmosphere to obtain light and heavy components; S2, the light component is mixed with a crosslinking agent and a catalyst, and a thermal polycondensation crosslinking reaction is carried out under an inert atmosphere to obtain a preliminary crosslinking product; S3, the preliminary cross-linked product is cured and pre-oxidized in a mixture of oxygen and inert gas to obtain a hard carbon precursor; S4. Under an inert atmosphere, the hard carbon precursor is carbonized to obtain hard carbon material.
2. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In step S1, the extraction temperature is raised to 300–340°C, and the time is 2–5 hours.
3. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In step S2, the mass ratio of crosslinking agent to light component is 1:5 to 10, and the mass ratio of catalyst to light component is 1:10 to 20.
4. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In step S2, the temperature of the thermal polycondensation crosslinking reaction is 120–160°C, and the crosslinking time is 12–17 h.
5. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In step S3, the inert gas content in the mixed gas is 90%–95% and the oxygen content is 5%–10%; the ventilation rate is 800–1200 sscm.
6. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In step S3, the curing and pre-oxidation temperature is 280–320°C, and the time is 2–4 hours.
7. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In step S4, the carbonization temperature is 1100–1500℃, the heating rate is 2–5℃ / min, and the holding time is 2–6h.
8. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In steps S1 and S2, the inert gas is nitrogen, and the gas flow rate is 800–1200 sscm; the heating extraction and thermal polycondensation processes are carried out under physical stirring conditions, with a stirring speed of 120–160 rpm.
9. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In step S2, the crosslinking agent is paraformaldehyde and / or terephthalic acid, and the catalyst is p-toluenesulfonic acid and / or concentrated sulfuric acid.
10. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, In step S3, the inert gas is nitrogen; the curing and pre-oxidation processes are carried out under physical stirring conditions, with a stirring speed of 120-160 rpm.
11. The method for preparing hard carbon materials from ethylene tar according to claim 1, characterized in that, The inert gas in step S4 is argon, and the gas flow rate is 60-100 sscm.