Preparation method and application of pitch-based branched porous carbon material

Abstract

The application discloses a preparation method of asphalt-based branched porous carbon material and application thereof, and relates to the technical field of carbon material preparation. The preparation method comprises the following steps: performing crushing treatment on asphalt, and performing softening treatment on the crushed asphalt; then, adding a polymer into the asphalt obtained through the softening treatment, uniformly stirring and mixing the asphalt and the polymer, and placing the obtained mixture in a high-pressure reaction kettle for reaction; adding a pore-forming agent into the obtained polymer doped precursor, wherein the pore-forming agent is polyether P123 or polyether F127; and performing carbonization and activation on the obtained polymer, wherein the pore-forming agent is completely removed in the carbonization process, and a pore structure is formed on the surface of the polymer, and the branched porous carbon material is obtained. The prepared porous carbon material can be applied to an electrode material, is beneficial to the rapid transmission of electrolyte ions, and has a wide application prospect in the field of preparation of cheap, environment-friendly and high-performance supercapacitors.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon material preparation, and in particular to a preparation method and application of a pitch-based branched porous carbon material. Background Art

[0002] Pitch, composed of polycyclic aromatic hydrocarbons and polycyclic carbides, is a coking byproduct with high carbon content, low ash content, and low cost. The coking industry currently lacks effective deep-processing technology for coal tar pitch, resulting in significant waste of coal tar pitch resources. Utilizing coal tar pitch effectively in battery electrode materials could transform waste into valuable resources, reducing environmental pollution.

[0003] At present, the application of porous carbon materials in supercapacitors is mainly limited by the low content of surface functional groups, poor wettability to electrolytes and too narrow pore size, which is not conducive to the entry and rapid transmission of electrolyte ions. Polymer doping can effectively improve the above problems. After polymer doping, porous carbon materials are conducive to activation and pore formation, thereby realizing the regulation of the pore structure of porous carbon materials. At present, the preparation method of doped porous carbon materials is mainly nitrogen doping, which has two types: one is to use ammonia and urea to modify the precursor and carbonization product of a type of carbon material. The other method is to directly carbonize nitrogen-containing precursors, such as polyaniline, polyacrylonitrile, polyurethane and melamine. However, these two methods still have shortcomings in improving the capacitance and cycle stability of supercapacitors. Therefore, the development of excellent electrode materials is crucial to the preparation of high-performance supercapacitors.

[0004] Current research on coal tar primarily focuses on the preparation of porous carbon materials, carbon nanofibers, carbon films, and carbon microspheres. While these carbon materials possess high specific surface area and pore volume, their poor electrical conductivity precludes their application in electrochemistry. He et al. used coal tar pitch to prepare 3D interconnected graphene nanocapsules. Superelectrical performance tests demonstrated that the material exhibited excellent specific capacitance and cycling stability, with a specific capacitance of 277 F / g at a current density of 0.05 A / g and 194 F / g at a high current density of 20 A / g. After 15,000 cycles in a 6 M KOH electrolyte, its capacity retained approximately 97.4%. However, this method is complex, requires demanding conditions, and has high production and equipment costs, making it difficult to widely adopt in industrial production.

[0005] This shows that the existing technology needs further improvement. Summary of the Invention

[0006] One of the purposes of the present invention is to provide a method for preparing asphalt-based branched porous carbon materials, which uses asphalt as raw material, crushes and softens the asphalt, adds a polymer for grafting modification, and then places it in a high-pressure reactor for reaction. Thereafter, a porogen is added to the polymer, and pores are formed through carbonization and activation processes. The prepared porous carbon material can be used in electrode materials, which is conducive to the rapid transmission of electrolyte ions.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0009] a. Crush the asphalt and soften the crushed asphalt;

[0010] b. Adding a polymer to the asphalt obtained by the softening treatment, wherein the polymer is a mixture of lignin and phenol, stirring the asphalt and the polymer until uniformly mixed, placing the resulting mixture in an autoclave for reaction at a temperature of 170-190° C. for 3-5 hours, and then naturally cooling the mixture at room temperature after the reaction to obtain a polymer-doped precursor;

[0011] c. Adding a pore-forming agent to the polymer-doped precursor obtained in step b, wherein the pore-forming agent is polyether P123 or polyether F127;

[0012] d. Carbonizing and activating the polymer obtained in step c. During the carbonization process, the pore-forming agent is completely removed and a pore structure is formed on the surface of the polymer.

[0013] In the above-mentioned method for preparing a pitch-based branched porous carbon material, in step a, the particle size of the pitch after the pulverization treatment is below 0.200 mm.

[0014] The above-mentioned method for preparing a pitch-based branched porous carbon material, wherein the mass ratio of lignin to phenol is 5:1.

[0015] In the above-mentioned method for preparing a pitch-based branched porous carbon material, in step a, the pitch is softened by dissolving it in a solvent or heating it.

[0016] In the above-mentioned method for preparing a pitch-based branched porous carbon material, solvent benzene or toluene is added to the pulverized pitch to dissolve it.

[0017] In the above-mentioned method for preparing a pitch-based branched porous carbon material, the pulverized pitch is heated at a temperature of 180 to 220° C. for softening.

[0018] In the above-mentioned method for preparing a pitch-based branched porous carbon material, in step d, the carbonization temperature is 700-850°C and the carbonization time is 1-2h; the activation is carried out in a water vapor or carbon dioxide atmosphere at an activation temperature of 900-1100°C.

[0019] In the above-mentioned method for preparing a pitch-based branched porous carbon material, the amount of polymer added is 8% to 30% of the mass of the asphalt.

[0020] In the above-mentioned method for preparing a pitch-based branched porous carbon material, the amount of polymer added is 10% of the mass of the asphalt.

[0021] A second object of the present invention is to provide the application of the porous carbon material prepared by the above-mentioned method for preparing the pitch-based branched porous carbon material in battery electrode materials.

[0022] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0023] (1) The present invention uses asphalt as raw material, which is widely available and inexpensive.

[0024] (2) In the preparation method of the present invention, the asphalt is first crushed, and the crushed asphalt can be better mixed with the polymer; the crushed asphalt is softened, and the polymer is added to react, and the asphalt is placed in a high-pressure reactor to fully react to form a branched polymer; then a pore-forming agent is added to the polymer, and the defective structure can be removed under the action of high temperature during the subsequent carbonization and activation, thereby forming pores.

[0025] (3) The present invention uses asphalt as raw material, grafts it with a mixture of lignin and phenol, and uses a polyether compound as a porogen. As the reaction continues, polymer carbon dots are first generated, and the polymer carbon dots grow from small to large and cross-linked with each other. The formed precursor is carbonized and activated, and is activated in a water vapor and carbon dioxide atmosphere to form a branched carbon material.

[0026] (4) The specific surface area of ​​the porous carbon material prepared by the present invention is 380 to 1400 m2 / g, and the pore volume is 330 to 510 mL / 100 g.

[0027] (5) The carbon material prepared by the present invention has excellent electrical conductivity and good cycle performance, which can improve battery charge and discharge efficiency, reduce internal resistance, increase battery energy density, reduce costs, extend battery life, and reduce battery defect rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below with reference to the accompanying drawings:

[0029] Figure 1This is the full XPS spectrum of the porous carbon material prepared in the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0031] In the description of this application, unless otherwise specified, " / " means "or". For example, A / B can mean A or B. "And / or" in this document is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0032] The raw materials described in the present invention can all be purchased through commercial channels.

[0033] The “specific capacity” mentioned in the present invention is “mass specific capacity”.

[0034] The technical solution of the present application is further described in detail below with reference to the accompanying drawings.

[0035] Example 1:

[0036] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0037] Step 1: crush the asphalt into pieces smaller than 0.2 mm using a small crusher; weigh 10 g of the crushed asphalt and soften it, then add benzene to dissolve the asphalt;

[0038] Step 2: Add a polymer to the asphalt obtained by the softening treatment. The polymer is a mixture of lignin and phenol. The amount of polymer added is 10% of the asphalt mass. Stir the asphalt and polymer by a magnetic stirrer to mix them evenly. Place them in a wide-mouthed conical beaker and heat them at 45°C. Evaporate the organic solvent benzene. Then, place the resulting mixture in a high-pressure reactor for reaction at 180°C for 4 hours. After the reaction is completed, cool it naturally at room temperature, collect the material in the lower layer, and dry it at 110°C for 24 hours to obtain a polymer-doped precursor.

[0039] Step 3: adding a pore-forming agent, polyether P123, to the polymer-doped precursor obtained in step 2; the amount of the pore-forming agent, polyether P123, added is 20% of the mass of the asphalt;

[0040] Step 4: Place the polymer obtained in step 3 into a muffle furnace, heat to 850°C at a heating rate of 5°C / min, and carbonize at a constant temperature for 2 hours;

[0041] Step 5: The precursor obtained by carbonization in step 4 is heated to 1100° C. at a heating rate of 5° C. / min in a water vapor atmosphere to obtain a porous carbon material.

[0042] The full XPS spectrum of the porous carbon material prepared in this example is as follows Figure 1 shown.

[0043] After testing, the porous carbon material obtained in this embodiment has a specific surface area of ​​1400 m2 / g, a pore volume of 500 mL / 100 g, and a pore distribution showing a multi-level pore structure.

[0044] The porous carbon material prepared in this embodiment is applied to electrode materials. The specific application method is: the electrochemical performance of the supercapacitor is examined by cyclic voltammetry, constant current charge and discharge test and AC impedance test. Cyclic voltammetry test is carried out on Chenhua 760E with a scan rate of 5mV / s to 1000mV / s and a voltage range of 0 to 1V. The frequency range in the AC impedance test is 10mHz to 100kHz, the amplitude is 10mV, and the current density range in the constant current charge and discharge test is 1 to 50Ag. -1

[0045] Application results: When used as anode material in the electrochemical workstation, even at 5Ag -1 Even at high current density, its specific capacity is still as high as 450mAh g -1 In 1Ag -1 After 200 cycles at a current density of 1.5 GHz, the specific capacity is 400 mAh g -1 .

[0046] Example 2:

[0047] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0048] Step 1: crush the asphalt into pieces smaller than 0.2 mm using a small crusher; weigh 10 g of the crushed asphalt and soften it, then add benzene to dissolve the asphalt;

[0049] Step 2: Add a polymer to the asphalt obtained by the softening treatment. The polymer is an epoxy resin, and the amount of the polymer added is 10% of the asphalt mass. Stir the asphalt and the polymer by a magnetic stirrer to mix them evenly. Place them in a wide-mouthed conical beaker and heat them at 45°C. Evaporate the organic solvent benzene. Then, place the resulting mixture in a high-pressure reactor for reaction at 180°C for 4 hours. After the reaction is completed, cool it naturally at room temperature, collect the material in the lower layer, and dry it at 110°C for 24 hours to obtain a polymer-doped precursor.

[0050] Step 3: adding a pore-forming agent, polyether P123, to the polymer-doped precursor obtained in step 2; the amount of the pore-forming agent, polyether P123, added is 20% of the mass of the asphalt;

[0051] Step 4: Place the polymer obtained in step 3 into a muffle furnace, heat to 750°C at a heating rate of 5°C / min, and carbonize at a constant temperature for 2 hours;

[0052] Step 5: The precursor obtained by carbonization in step 4 is heated to 950° C. at a heating rate of 5° C. / min in a water vapor atmosphere to obtain a porous carbon material.

[0053] After testing, the porous carbon material obtained in this embodiment has a specific surface area of ​​1300 m2 / g, a pore volume of 480 mL / 100 g, and a multi-level pore structure.

[0054] The porous carbon material prepared in this embodiment is applied to electrode materials. The specific application method is: the electrochemical performance of the supercapacitor is examined by cyclic voltammetry, constant current charge and discharge test and AC impedance test. Cyclic voltammetry test is carried out on Chenhua 760E with a scan rate of 5mV / s to 1000mV / s and a voltage range of 0 to 1V. The frequency range in the AC impedance test is 10mHz to 100kHz, the amplitude is 10mV, and the current density range in the constant current charge and discharge test is 1 to 50Ag. -1 .

[0055] Application results: When used as an anode material in an electrochemical workstation, even at 5A g -1 Even at high current density, its specific capacity is still as high as 439 mAh g -1 At 1A g -1 After 200 cycles at a current density of 1.5 GHz, the specific capacity is 320 mAh g -1 .

[0056] Example 3:

[0057] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0058] Step 1: crush the asphalt into pieces smaller than 0.2 mm using a small crusher; weigh 10 g of the crushed asphalt and soften it, then add benzene to dissolve the asphalt;

[0059] Step 2: Add polymer to the asphalt obtained by softening treatment. The polymer is epoxy resin and lignin. The amount of polymer added is 10% of the asphalt mass. Stir the asphalt and polymer by a magnetic stirrer to mix them evenly. Place them in a wide-mouthed conical beaker and heat them at 45°C. Evaporate the organic solvent benzene. Then, place the resulting mixture in a high-pressure reactor for reaction at 180°C for 4 hours. After the reaction is completed, cool it naturally at room temperature, collect the material in the lower layer, and dry it at 110°C for 24 hours to obtain a polymer-doped precursor.

[0060] Step 3: Add the pore-forming agent polyether P123 to the polymer-doped precursor obtained in step 2; the amount of the pore-forming agent polyether P123 added is 20% of the mass of the asphalt.

[0061] Step 4: Place the polymer obtained in step 3 into a muffle furnace, heat to 750°C at a heating rate of 5°C / min, and carbonize at a constant temperature for 2 hours;

[0062] Step 5: The precursor obtained by carbonization in step 4 is heated to 950° C. at a heating rate of 5° C. / min in a water vapor atmosphere to obtain a porous carbon material.

[0063] After testing, the porous carbon material obtained in this embodiment has a specific surface area of ​​1450 m2 / g, a pore volume of 530 mL / 100 g, and a pore distribution showing a multi-level pore structure.

[0064] Example 4:

[0065] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0066] Step 1: crush the asphalt into pieces smaller than 0.2 mm using a small crusher; weigh 10 g of the crushed asphalt and heat it to 200°C for softening;

[0067] Step 2: Adding a polymer to the asphalt obtained by the softening treatment, wherein the polymer is a mixture of lignin and phenol, and the amount of the polymer added is 10% of the mass of the asphalt. The asphalt and the polymer are stirred and mixed uniformly by a magnetic stirrer to obtain a polymer-doped precursor;

[0068] Step 3: adding a pore-forming agent, polyether P123, to the polymer-doped precursor obtained in step 2; the amount of the pore-forming agent, polyether P123, added is 20% of the mass of the asphalt;

[0069] Step 4: Place the polymer obtained in step 3 into a muffle furnace, heat to 750°C at a heating rate of 5°C / min, and carbonize at a constant temperature for 2 hours;

[0070] Step 5: The precursor obtained by carbonization in step 4 is heated to 950° C. at a heating rate of 5° C. / min in a water vapor atmosphere to obtain a porous carbon material.

[0071] After testing, the porous carbon material obtained in this embodiment has a specific surface area of ​​1150 m2 / g, a pore volume of 380 mL / 100 g, and a multi-level pore structure.

[0072] Example 5:

[0073] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0074] Step 1: crush the asphalt into pieces smaller than 0.2 mm using a small crusher; weigh 10 g of the crushed asphalt and heat it to 200°C for softening;

[0075] Step 2: Adding a polymer to the softened asphalt, wherein the polymer is a mixture of lignin and epoxy resin, and the amount of the polymer added is 10% of the asphalt mass. The asphalt and the polymer are stirred and mixed uniformly by a magnetic stirrer to obtain a polymer-doped precursor;

[0076] Step 3: Add the pore-forming agent polyether F127 to the polymer-doped precursor obtained in step 2; the amount of the pore-forming agent polyether F127 added is 20% of the mass of the asphalt.

[0077] Step 4: Place the polymer obtained in step 3 into a muffle furnace, heat to 750°C at a heating rate of 5°C / min, and carbonize at a constant temperature for 2 hours;

[0078] Step 5: The precursor obtained by carbonization in step 4 is heated to 950° C. at a heating rate of 5° C. / min in a water vapor atmosphere to obtain a porous carbon material.

[0079] After testing, the porous carbon material obtained in this embodiment has a specific surface area of ​​1200 m2 / g, a pore volume of 410 mL / 100 g, and a pore distribution showing a multi-level pore structure.

[0080] The porous carbon material prepared in this embodiment is applied to electrode materials. The specific application method is: the electrochemical performance of the supercapacitor is examined by cyclic voltammetry, constant current charge and discharge test and AC impedance test. Cyclic voltammetry test is carried out on Chenhua 760E with a scan rate of 5mV / s to 1000mV / s and a voltage range of 0 to 1V. The frequency range in the AC impedance test is 10mHz to 100kHz, the amplitude is 10mV, and the current density range in the constant current charge and discharge test is 1 to 50Ag. -1 .

[0081] Application results: When used as anode material in the electrochemical workstation, even at 5Ag -1Even at high current density, its specific capacity is still as high as 400mAh g -1 In 1Ag -1 After 200 cycles at a current density of 1.5 GHz, the specific capacity is 285 mAh g -1 .

[0082] Example 6:

[0083] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0084] Step 1: crush the asphalt into pieces smaller than 0.2 mm using a small crusher; weigh 10 g of the crushed asphalt and soften it, then add benzene to dissolve the asphalt;

[0085] Step 2: Add a polymer to the asphalt obtained by the softening treatment. The polymer is a mixture of lignin and phenol. The amount of polymer added is 10% of the asphalt mass. Stir the asphalt and polymer by a magnetic stirrer to mix them evenly. Place them in a wide-mouthed conical beaker and heat them at 45°C. Evaporate the organic solvent benzene. Then, place the resulting mixture in a high-pressure reactor for reaction at 180°C for 4 hours. After the reaction is completed, cool it naturally at room temperature, collect the material in the lower layer, and dry it at 110°C for 24 hours to obtain a polymer-doped precursor.

[0086] Step 3: adding a pore-forming agent, polyether P123, to the polymer-doped precursor obtained in step 2; the amount of the pore-forming agent, polyether P123, added is 20% of the mass of the asphalt;

[0087] Step 4: Place the polymer obtained in step 3 into a muffle furnace, heat to 850°C at a heating rate of 5°C / min, and carbonize at a constant temperature for 2 hours;

[0088] Step 5: The precursor obtained by carbonization in step 4 is heated to 1100° C. at a heating rate of 5° C. / min in a water vapor atmosphere to obtain a porous carbon material.

[0089] After testing, the porous carbon material obtained in this embodiment has a specific surface area of ​​1200 m2 / g, a pore volume of 400 mL / 100 g, and a pore distribution showing a multi-level pore structure.

[0090] The porous carbon material prepared in this embodiment is applied to electrode materials. The specific application method is: the electrochemical performance of the supercapacitor is examined by cyclic voltammetry, constant current charge and discharge test and AC impedance test. Cyclic voltammetry test is carried out on Chenhua 760E with a scan rate of 5mV / s to 1000mV and a voltage range of 0 to 1V. The frequency range in the AC impedance test is 10mHz to 100kHz, the amplitude is 10mV, and the current density range in the constant current charge and discharge test is 1 to 50Ag. -1

[0091] Application results: When used as anode material in the electrochemical workstation, even at 5Ag -1 Even at high current density, its specific capacity is still as high as 375mAh g -1 At 1A g -1 After 200 cycles at a current density of 1.5 GHz, the specific capacity is 255 mAh g -1 .

[0092] Comparative Example 1:

[0093] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0094] Step 1: crush the asphalt into pieces smaller than 0.2 mm using a small crusher; weigh 10 g of the crushed asphalt and soften it, then add benzene to dissolve the asphalt;

[0095] Step 2: Add a polymer to the asphalt obtained by the softening treatment. The polymer is a mixture of lignin and phenol. The amount of polymer added is 10% of the asphalt mass. Stir the asphalt and polymer by a magnetic stirrer to mix them evenly. Place them in a wide-mouthed conical beaker and heat them at 45°C. Evaporate the organic solvent benzene. Then, place the resulting mixture in a high-pressure reactor for reaction at 180°C for 4 hours. After the reaction is completed, cool it naturally at room temperature, collect the material in the lower layer, and dry it at 110°C for 24 hours to obtain a polymer-doped precursor.

[0096] Step 3: Place the polymer obtained in step 2 into a muffle furnace, heat to 850°C at a heating rate of 5°C / min, and carbonize at a constant temperature for 2 hours;

[0097] Step 4: The precursor obtained by carbonization in step 3 is heated to 1100° C. at a heating rate of 5° C. / min in a water vapor atmosphere to obtain a porous carbon material.

[0098] After testing, the porous carbon material obtained in this comparative example has a specific surface area of ​​500 m2 / g, a pore volume of 100 mL / 100 g, and a multi-level pore structure.

[0099] The porous carbon material prepared in this comparative example is applied to electrode materials. The specific application method is as follows: the electrochemical performance of the supercapacitor is investigated by cyclic voltammetry, constant current charge-discharge test and AC impedance test. The cyclic voltammetry test is carried out on Chenhua 760E with a scan rate of 5mV / s to 1000mV and a voltage range of 0 to 1V. The frequency range in the AC impedance test is 10mHz to 100kHz, the amplitude is 10mV, and the current density range in the constant current charge-discharge test is 1 to 50A g -1

[0100] Application results: When used as an anode material in an electrochemical workstation, even at 5A g -1 Even at high current density, its specific capacity is still as high as 225mAh g -1 At 1A g -1 After 200 cycles at a current density of 1.5 GHz, the specific capacity is 155 mAh g -1 .

[0101] Comparative Example 2:

[0102] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0103] Step 1: crush the asphalt into pieces smaller than 0.2 mm using a small crusher; weigh 10 g of the crushed asphalt and soften it, then add benzene to dissolve the asphalt;

[0104] Step 2: Add a polymer to the softened asphalt, wherein the polymer is a mixture of lignin and phenol, and the amount of the polymer added is 10% of the asphalt mass. Stir the asphalt and polymer using a magnetic stirrer until they are evenly mixed. Place the mixture in a wide-mouthed conical beaker and heat it at 45°C to evaporate the organic solvent, benzene.

[0105] Step 3: Place the polymer obtained in step 2 into a muffle furnace, heat to 850°C at a heating rate of 5°C / min, and carbonize at a constant temperature for 2 hours;

[0106] Step 4: The precursor obtained by carbonization in step 3 is heated to 1100° C. at a heating rate of 5° C. / min in a water vapor atmosphere to obtain a porous carbon material.

[0107] After testing, the porous carbon material obtained in this comparative example has a specific surface area of ​​500 m2 / g, a pore volume of 100 mL / 100 g, and a multi-level pore structure.

[0108] The porous carbon material prepared in this comparative example is applied to electrode materials. The specific application method is as follows: the electrochemical performance of the supercapacitor is investigated by cyclic voltammetry, constant current charge-discharge test and AC impedance test. The cyclic voltammetry test is carried out on Chenhua 760E with a scan rate of 5mV / s to 1000mV and a voltage range of 0 to 1V. The frequency range in the AC impedance test is 10mHz to 100kHz, the amplitude is 10mV, and the current density range in the constant current charge-discharge test is 1 to 50A g -1

[0109] Application results: When used as an anode material in an electrochemical workstation, even at 5A g -1 Even at high current density, its specific capacity is still as high as 220mAh g -1 At 1A g-1 After 200 cycles at a current density of 1.5 GHz, the specific capacity is 150 mAh g -1 .

[0110] Comparative Example 3:

[0111] A method for preparing a pitch-based branched porous carbon material comprises the following steps:

[0112] Step 1: crush the asphalt into pieces less than 0.2mm using a small crusher;

[0113] Step 2: Take 10 parts (10g) of coal tar pitch and put them into a muffle furnace. Heat them to 650℃, 700℃, 750℃, 800℃ and 850℃ at a heating rate of 5℃ / min, and carbonize them at the same temperature for 1h and 2h respectively.

[0114] Step 3: Activation: Place the carbonized asphalt in a muffle furnace and heat it to 950°C at a heating rate of 5°C / min under a steam atmosphere.

[0115] After testing, the porous carbon material obtained in this comparative example has a specific surface area of ​​500 m2 / g, a pore volume of 100 mL / 100 g, and a multi-level pore structure.

[0116] The porous carbon material prepared in this comparative example is applied to electrode materials. The specific application method is as follows: the electrochemical performance of the supercapacitor is investigated by cyclic voltammetry, constant current charge-discharge test and AC impedance test. The cyclic voltammetry test is carried out on Chenhua 760E with a scan rate of 5mV / s to 1000mV and a voltage range of 0 to 1V. The frequency range in the AC impedance test is 10mHz to 100kHz, the amplitude is 10mV, and the current density range in the constant current charge-discharge test is 1 to 50A g -1 .

[0117] Application results: When used as an anode material in an electrochemical workstation, even at 5A g -1 Even at high current density, its specific capacity is still as high as 220mAh g -1 At 1A g -1 After 200 cycles at a current density of 1.5 GHz, the specific capacity is 150 mAh g -1 .

[0118] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. Any appropriate changes and modifications to the above embodiments should fall within the scope of protection claimed in the present application as long as they are within the spirit of the present application.

Claims

1. A method for preparing a pitch-based branched porous carbon material, characterized in that: The following steps are involved: a. Crush the asphalt and soften the crushed asphalt; b. Adding a polymer to the asphalt obtained by the softening treatment, wherein the polymer is a mixture of lignin and phenol, stirring the asphalt and the polymer until uniformly mixed, placing the resulting mixture in an autoclave for reaction at a temperature of 170-190° C. for 3-5 hours, and naturally cooling at room temperature after the reaction, and drying at 100-120° C. to obtain a polymer-doped precursor; c. Adding a pore-forming agent to the polymer-doped precursor obtained in step b, wherein the pore-forming agent is polyether P123 or polyether F127; the mass ratio of lignin to phenol is 1-5:1, and the amount of the pore-forming agent added is 10%-20% of the mass of the asphalt; d. Carbonizing and activating the polymer obtained in step c. During the carbonization process, the pore-forming agent is completely removed and a pore structure is formed on the surface of the polymer. The amount of polymer added is 8% to 30% of the asphalt mass.

2. The method for preparing a pitch-based branched porous carbon material according to claim 1, wherein: In step a, the particle size of the asphalt after the crushing treatment is below 0.200 mm.

3. The method for preparing a pitch-based branched porous carbon material according to claim 1, wherein: In step a, the asphalt is softened by dissolving it with a solvent or heating it.

4. The method for preparing a pitch-based branched porous carbon material according to claim 3, wherein: Add solvent benzene or toluene to the pulverized asphalt to dissolve it.

5. The method for preparing a pitch-based branched porous carbon material according to claim 3, wherein: The crushed asphalt is heated at a temperature of 180-220°C for softening.

6. The method for preparing a pitch-based branched porous carbon material according to claim 1, wherein: In step d, the carbonization temperature is 700-850° C. and the carbonization time is 1-2 hours; the activation is carried out in a water vapor or carbon dioxide atmosphere at an activation temperature of 900-1100° C.

7. The method for preparing a pitch-based branched porous carbon material according to claim 1, wherein: The amount of polymer added is 10% of the asphalt mass.

8. Use of the porous carbon material prepared according to the method for preparing a pitch-based branched porous carbon material according to any one of claims 1 to 7 in battery electrode materials.

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