CN112850708A - Preparation method and application of nitrogen-doped porous carbon material with high specific surface area - Google Patents
Preparation method and application of nitrogen-doped porous carbon material with high specific surface area Download PDFInfo
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Abstract
The invention discloses a preparation method and application of a nitrogen-doped porous carbon material with a high specific surface area. The high specific surface area nitrogen-doped porous carbon material is prepared by taking bacterial cellulose as a carbon precursor, taking magnesium nitrate hexahydrate as a nitrogen dopant, a pore-forming activator and a template agent, absorbing a magnesium nitrate hexahydrate solution through the bacterial cellulose, then carrying out high-temperature carbonization and dilute hydrochloric acid washing. The magnesium nitrate hexahydrate has the functions of serving as an activating agent, a doping agent and a template at the same time, and is used for doping nitrogen elements in the carbon material, so that the aperture is optimized, and the specific surface area is increased. The prepared carbon material has the characteristics of communicated pore structure, high specific surface area, many active sites, high conductivity and the like, and has excellent electrochemical performance when being applied to a potassium ion battery as a negative electrode material.
Description
Technical Field
The invention belongs to the field of chemical energy materials, and particularly relates to preparation of a nitrogen-doped porous carbon material with a high specific surface area, in particular to a preparation method and application of the nitrogen-doped porous carbon material with the high specific surface area for a potassium ion battery.
Background
With the rising population, fossil energy is exhausted day by day, and energy consumption and environmental burden are constantly increasing, and the problem that people are keenly solved is developing high-efficient, sustainable and clean novel energy storage equipment. Lithium ion batteries have been increasingly demanded in recent years as a main power source for electric vehicles and electronic devices. However, because the abundance of lithium resources in the earth crust is low, and the large-scale application cost is high, the development of rechargeable batteries capable of replacing lithium ion batteries is a very urgent problem to be solved. In recent years, potassium ion batteries have become one of the most likely alternative ion batteries for lithium ion batteries due to their advantages of abundant potassium reserves, low potassium compound prices, high ionic conductivity of potassium electrolytes, and the like. However, the potassium ion has a large radius and slow kinetics, which may cause problems of volume expansion and poor rate capability during the intercalation/deintercalation process of potassium ions. Some commonly used negative electrode materials for lithium ion batteries cannot be applied to potassium ion batteries because of these problems. Therefore, the research on the potassium ion battery cathode material with high capacity, good rate capability and long cycle life is one of the key problems for realizing the large-scale application of the potassium ion battery.
In order to solve the above problems, researchers have developed various anode materials such as carbon materials, alloys, metal compounds, organic compounds, and the like. Among them, carbon-based materials have been the hot research of potassium ion battery negative electrode materials due to high conductivity, low cost and chemical stability, but some carbon materials also have the problems of low capacity and poor rate capability. For example, the theoretical capacity of the graphite in the potassium ion battery is only 279 mA h g-1Meanwhile, the application is limited by the huge volume expansion and low diffusion kinetics during the potassium ion intercalation/deintercalation process. To solve these problems, many efforts have been made to optimize the carbon anode material, such as increasing defects to increase active sites, increasing specific surface area to increase potassium storage capacity, and the like. Several individual optimization methods, such as heterogeneous element doping, activation method, template method are representative optimization methods; the heterogeneous atom doping improves the conductivity of the carbon material and the wettability to the electrolyte mainly by adjusting the electronic characteristics, and forms an additional pseudo capacitor through the oxidation-reduction reaction of the surface functional groups. The activation method can improve the surface area of the carbon material and adjust the pore structure. For example, nitrogen doping is a material which is researched more in recent years and improves the potassium storage performance, and has the advantages of introducing defects, improving the conductivity, optimizing the carbon layer spacing and the like. The activation method mainly etches the carbon matrix through oxidation-reduction reaction between the activating agent and the carbon matrix, and the generated gas further increases the porosity to form the high-specific-surface-area porous structure carbon. And the template method can introduce the structure of the template into the carbon, thereby forming carbon with a specific morphology. However, the above-mentioned heterogeneous element doping and activating method in the prior art,The template method can be carried out alone, and each method has limited improvement in increasing the specific surface area to improve the potassium storage capacity, and therefore, there is a need to search for a new material that can produce a higher potassium storage capacity and can be applied to a potassium ion battery.
Disclosure of Invention
The invention discloses a preparation method of a nitrogen-doped porous carbon material with a high specific surface area, and particularly relates to a nitrogen-doped porous carbon material with a high specific surface area, which can be used for a potassium ion battery. The prepared material has the characteristics of communicated pore structure, high specific surface area, many active sites, high conductivity and the like, and has excellent electrochemical performance when being applied to a potassium ion battery as a negative electrode material.
The preparation method of the nitrogen-doped porous carbon material with the high specific surface area comprises the steps of taking bacterial cellulose as a carbon precursor, taking magnesium nitrate hexahydrate as a nitrogen doping agent, a pore-forming activating agent and a template agent, absorbing a magnesium nitrate hexahydrate solution through the bacterial cellulose, then carrying out high-temperature carbonization and dilute hydrochloric acid washing, and finally preparing the nitrogen-doped porous carbon material with the high specific surface area. The magnesium nitrate hexahydrate has the functions of serving as an activating agent, a doping agent and a template at the same time, and is used for doping nitrogen elements in the carbon material, so that the aperture is optimized, and the specific surface area is increased.
The method organically combines three optimization methods of heterogeneous element doping, activating and template methods, selects magnesium nitrate hexahydrate as an activating agent, a doping agent and a template, and generates NO through pyrolysis of the magnesium nitrate hexahydrate in high-temperature carbonization2、O2The gas may be activated and nitrogen doped while uniformly dispersing the magnesium oxide particle template in the carbon matrix. The magnesium oxide template has higher thermal stability, does not react with a carbon precursor at high temperature, and the obtained carbon can be washed away by using a diluted acid solution, so that the operation is simple. The bacterial cellulose has high solution adsorbability and a large number of hydroxyl groups on the surface, so that chemical modification is facilitated, and simple pretreatment of a carbon precursor is easily realized.
The preparation process comprises the steps of soaking bacterial cellulose in a magnesium nitrate hexahydrate solution for pretreatment, and then obtaining the nitrogen-doped porous carbon material with high specific surface area through the processes of high-temperature carbonization, acid washing, water washing and drying, wherein the material has nitrogen doping, high specific surface area and communicated pore structures. The material is used as a negative electrode material of a potassium ion battery, and shows high specific capacity, excellent rate capability and cycling stability. The novel nitrogen-doped porous carbon material with the high specific surface area is obtained by the preparation method of pretreatment, high-temperature carbonization, acid washing, washing and drying, a large number of pores and defects are introduced by the activation and nitrogen doping effects of gas generated by high-temperature decomposition of magnesium nitrate hexahydrate, the conductivity, the electrode wettability and the potassium storage capacity are increased, the interlayer spacing is optimized, and the volume expansion in the circulation process is slowed down. And removing magnesium oxide particles generated after carbonization through acid washing to further optimize the pore structure, increasing the specific surface area and finally forming the interconnected porous structure carbon material.
The potassium ion battery carbon material has attracted extensive attention of researchers because of the advantages of low cost, easy preparation, safety, environmental protection, good conductivity and the like. However, a major challenge currently facing potassium ion batteries is that the potassium ion radius (1.38 a) is larger than the lithium ion radius (0.76 a), and when some lithium ion battery negative electrode materials are applied in potassium ion batteries, volume expansion may occur during the potassium ion intercalation/deintercalation process, resulting in low capacity, poor rate performance and poor cycle stability of the potassium ion batteries. Therefore, designing and preparing the carbonaceous material with low volume expansion rate, high specific surface area and large interlayer spacing and carrying out element doping on the carbonaceous material are effective ways for obtaining high-performance electrode materials.
The nitrogen-doped porous carbon material with high specific surface area prepared by the invention is porous carbon prepared by simultaneously utilizing a three-in-one method of doping, activating and introducing a template. The porous carbon nano material has the properties of a carbon material, such as high chemical stability, good conductivity, low price and the like; the introduction of the pore structure ensures that the porous structure has the characteristics of large specific surface area, controllable pore channel structure, adjustable pore diameter and the like. The nitrogen-doped porous carbon with high specific surface area prepared by the invention also has the following characteristics: (1) the interconnected pore structure formed by taking the mesopores as the main body has very high specific surface area, the microstructure can shorten the ion transmission distance, increase the contact area of the electrode and the electrolyte, and the high specific surface area can also contain more potassium ions and relieve the volume expansion caused by the embedding/removing process of the potassium ions. (2) Nitrogen doping can increase the electronegativity of the carbon material to increase conductivity and increase the carbon layer spacing by introducing a large number of active defects in the carbon matrix.
The characteristics can improve the transmission and diffusion rate of potassium ions and relieve the problem of volume expansion, so that the potassium ion battery serving as the cathode material has high reversible capacity and rate capability and stable long-term cycle performance. Therefore, the invention utilizes the gas generated by the pyrolysis of the inorganic salt magnesium nitrate hexahydrate for activation and doping, and simultaneously generates magnesium oxide particles to form the template. The nitrogen-doped porous carbon material with high specific surface area is finally prepared by combining an activation method, heteroatom doping and a template method, nitrogen-oxygen double doping and a unique pore structure provide more active sites and potassium storage capacity, volume expansion caused by potassium ion intercalation/deintercalation is slowed down, and the material shows excellent electrochemical performance as a potassium ion cathode material.
The preparation method of the invention is as follows:
a preparation method of a nitrogen-doped porous carbon material with high specific surface area is characterized by comprising the following steps:
(1) selecting a proper biomass carbon precursor A and a proper material B which is used as an activating agent, a doping agent and a template agent in a three-in-one manner;
(2) pretreatment: preparing an aqueous solution of a material B, cutting the biomass carbon precursor A into thin slices, completely immersing the thin slices in the aqueous solution, strongly stirring, taking out, and freeze-drying to obtain a pretreated carbon precursor;
(3) carbonizing, activating and generating a template: putting the product obtained after freeze drying into a tube furnace, and carbonizing and activating at high temperature under inert atmosphere;
(4) removing and cleaning the template: and (3) cleaning the carbonized sample in dilute hydrochloric acid and deionized water to remove template particles and impurities, and then drying in an oven to finally obtain the nitrogen-doped porous carbon material with high specific surface area.
Further, selecting bacterial cellulose with the thickness of 0.3cm as a carbon precursor A in the step (1); selecting magnesium nitrate hexahydrate as a material B for three-in-one use of an activating agent, a doping agent and a template agent; NO produced by pyrolysis of magnesium nitrate hexahydrate2、O2The gas can be activated and doped with nitrogen, and meanwhile, the magnesium oxide particle template is uniformly dispersed in the carbon matrix, the magnesium oxide particle template has higher thermal stability and does not react with the carbon precursor at high temperature, and the magnesium oxide particle template can be washed away by the obtained carbon sample containing the template by using diluted acid solution.
Furthermore, the nitrogen-doped porous carbon material with high specific surface area prepared by the method has an interconnected pore structure mainly composed of mesopores, and the carbon layer spacing is increased by introducing a large amount of active defects in the carbon matrix; the material can be applied to electrodes of potassium ion batteries; the microstructure of the material can shorten the ion transmission distance, increase the contact area of the electrode and the electrolyte, and the high specific surface area of the material can accommodate more potassium ions and relieve the volume expansion caused by the potassium ion embedding/removing process.
Further, in the step (2), the concentration of the magnesium nitrate hexahydrate aqueous solution is 0-1 mol/L.
Further, in the step (2), the concentration of the magnesium nitrate hexahydrate aqueous solution is 0.05 mol/L.
Further, in the step (3), the high-temperature carbonization and activation under the inert atmosphere specifically comprises: under inert atmosphere, heating to carbonization temperature, and keeping the temperature for a period of time; wherein the carbonization temperature is 600-1500 ℃, and the heat preservation time is 0-12 h.
Further, in step (3), at 55 mL min-1N of (A)2At 5 deg.C for min in atmosphere-1The temperature rise rate of (2) is increased to 800 ℃ and the temperature is kept for 2h at the temperature.
Further, the sample carbonized in the step (4) is fully washed in 2mol/L diluted hydrochloric acid and deionized water respectively to eliminate magnesium oxide particles and impurities, and a more porous structure is formed.
Further, in the step (4), the sample is placed in a vacuum drying oven at 80 ℃ for drying for 12 hours, so that the nitrogen-doped porous carbon material is obtained.
Further, the material can be applied to electrodes of potassium ion batteries.
The invention has the following beneficial effects:
(1) the preparation method prepares the porous carbon material by pretreatment, high-temperature carbonization and acid washing drying, finally prepares the nitrogen-doped porous carbon with high specific surface area by combining an activation method, heteroatom doping and a template method, provides more active sites and potassium storage capacity by nitrogen-oxygen double doping and a unique pore structure, slows down volume expansion caused by potassium ion intercalation/deintercalation, and has excellent electrochemical performance when applied to a potassium ion battery. The preparation method is safe and simple, has low cost, cannot damage the environment, can be used for large-scale preparation, and can meet the commercial requirement;
(2) the invention takes the biomass material bacterial cellulose as the carbon precursor, and has the advantages of environmental protection, high yield, low cost and the like. The bacterial cellulose contains a large amount of micro-mesopores, has high solution adsorbability and a large amount of hydroxyl on the surface, is convenient for chemical modification and easily realizes simple pretreatment of a carbon precursor;
(3) the invention selects magnesium nitrate hexahydrate as an activating agent, a doping agent and a template agent. By pyrolysis of magnesium nitrate hexahydrate in pyrocarbonization, NO is produced2、O2The gas may be activated and nitrogen doped while uniformly dispersing the magnesium oxide particle template in the carbon matrix. The magnesium oxide template has higher thermal stability, does not react with a carbon precursor at high temperature, and can be washed away by the obtained carbon with a diluted acid solution, so the operation is simple;
(4) the nitrogen-doped carbon material prepared by the method has a large number of pores and defects, increases the conductivity, the electrode wettability and the potassium storage capacity, optimizes the interlayer spacing and slows down the volume expansion in the circulation process. The high specific surface and the interconnected pore structure can provide a large electrode/electrolyte surface interface for charge transfer reaction, shorten the path of ion diffusion, and enhance the multiplying power capability in the charging and discharging process. The material has the characteristics of communicated pore structure, high specific surface area, many active sites, high conductivity and the like, can be applied to a potassium ion battery, and shows excellent electrochemical performance.
Drawings
Fig. 1 is a Scanning Electron Microscope (SEM) photograph of the high specific surface area nitrogen-doped porous carbon obtained in example 1.
Fig. 2 is a Scanning Electron Microscope (SEM) photograph of the high specific surface area nitrogen-doped porous carbon obtained in example 2.
Fig. 3 is a Scanning Electron Microscope (SEM) photograph of the high specific surface area nitrogen-doped porous carbon obtained in example 3.
Fig. 4 is a Scanning Electron Microscope (SEM) photograph of the nanofibrillar porous carbon obtained in comparative example 1.
Fig. 5 shows nitrogen adsorption/desorption curves of examples 1, 2, 3, and 1.
Fig. 6 is a graph showing the distribution of mesopores of examples 1, 2, 3 and 1.
Fig. 7 is a capacity graph of the assembled potassium ion batteries of examples 1, 2, 3 and 1 at different current densities.
FIG. 8 shows potassium ion cells assembled in examples 1, 2, 3 and 1 at 2A g-1Performance plot of 2500 cycles at current density.
Detailed Description
The technical solution of the present invention is illustrated by the following specific examples, but is not limited to the examples.
Example 1
Cutting 0.3cm thick bacterial cellulose into 4 × 8 cm sheets, and completely immersing the bacterial cellulose sheets in 200mL of 0.05mol/L Mg (NO)3)2 6H2And stirring the O aqueous solution strongly for 24 hours, taking out, and then freeze-drying for 72 hours to obtain the pretreated carbon precursor. Placing the obtained product into a tube furnace for 55 mL min-1N of (A)2At 5 deg.C for min in atmosphere-1At a temperature of 800 ℃ and at that temperatureAnd keeping the temperature for 2 h. And cooling to room temperature at the same temperature, washing the obtained product with dilute hydrochloric acid (2M) for 12h to remove MgO, washing with deionized water for multiple times, and finally drying the sample in a vacuum drying oven at 80 ℃ for 12h to obtain the nitrogen-doped porous carbon material.
Example 2
Cutting 0.3cm thick bacterial cellulose into 4 × 8 cm sheets, and completely immersing the bacterial cellulose sheets in 200mL of 0.03 mol/L Mg (NO)3)2 6H2And stirring the O aqueous solution strongly for 24 hours, taking out, and then freeze-drying for 72 hours to obtain the pretreated carbon precursor. Placing the obtained product into a tube furnace for 55 mL min-1N of (A)2At 5 deg.C for min in atmosphere-1The temperature rise rate of (2) was increased to 800 ℃ and the temperature was maintained at this temperature for 2 hours. And cooling to room temperature at the same temperature, washing the obtained product with dilute hydrochloric acid (2M) for 12h to remove MgO, washing with deionized water for multiple times, and finally drying the sample in a vacuum drying oven at 80 ℃ for 12h to obtain the nitrogen-doped porous carbon material.
Example 3
Cutting 0.3cm thick bacterial cellulose into 4 × 8 cm sheets, and completely immersing the bacterial cellulose sheets in 200mL of 0.07 mol/L Mg (NO)3)2 6H2And stirring the O aqueous solution strongly for 24 hours, taking out, and then freeze-drying for 72 hours to obtain the pretreated carbon precursor. Placing the obtained product into a tube furnace for 55 mL min-1N of (A)2At 5 deg.C for min in atmosphere-1The temperature rise rate of (2) was increased to 800 ℃ and the temperature was maintained at this temperature for 2 hours. And cooling to room temperature at the same temperature, washing the obtained product with dilute hydrochloric acid (2M) for 12h to remove MgO, washing with deionized water for multiple times, and finally drying the sample in a vacuum drying oven at 80 ℃ for 12h to obtain the nitrogen-doped porous carbon material.
Comparative example 1
Completely immersing a bacterial cellulose sheet with the thickness of 0.3cm and the size of 4 multiplied by 8 cm in 200mL deionized water solution, stirring strongly for 24h, taking out, and freeze-drying for 72h to obtain a pretreated carbon precursor. Placing the obtained product into a tube furnace for 55 mL min-1N of (A)2At 5 deg.C for min in atmosphere-1The temperature rise rate of (2) is increased to 800Keeping the temperature at the temperature for 2 h. And (3) cooling to room temperature at the same temperature, washing the obtained product with dilute hydrochloric acid (2M) for 12h, washing with deionized water for multiple times, and finally drying the sample in a vacuum drying oven at 80 ℃ for 12h to obtain the non-doped template-free carbon material.
Fig. 1, 2, 3, and 4 are SEM pictures of inventive materials of example 1, example 2, example 3, and comparative example 1, respectively. In all examples, the decomposition of magnesium nitrate hexahydrate at elevated temperature, gas activation and subsequent removal of the magnesium oxide particles, all add substantial porosity to the material. Example 1 shows a uniform inter-crosslinked porous morphology. Example 2 fractured fibrous structures were seen despite the increased porosity. Example 3 shows an agglomerated nanosheet structure, which may be caused by magnesium nitrate hexahydrate overactivation resulting in pore structure collapse. Comparative example 1 is a standard pyrolyzed nanofiber-like morphology. Fig. 5 and 6 are nitrogen adsorption/desorption isotherms and pore size distribution plots for the inventive materials of example 1, example 2, example 3, and comparative example 1, respectively. It can be seen from fig. 5 that all four samples exhibit type IV isotherms with obvious hysteresis loops, demonstrating that all materials have mesopores.
The specific surface areas of the materials of example 1, example 2, example 3 and comparative example 1 are 1355, 1025, 990 and 890m respectively2 g-1. The specific surface area of all examples is larger than that of comparative example 1, and the effect of increasing the specific surface area by decomposition of magnesium nitrate hexahydrate to generate gas during carbonization and subsequent elimination of magnesium oxide particles is also demonstrated. The pore volumes of example 1, example 2, example 3 and comparative example 1 were 2.101, 1.060, 1.509 and 0.711cm, respectively3 g-1The pore size distribution corresponding to fig. 6 shows the distribution of mesopores in examples 1, 2, 3 and comparative example 1, and the pore volume of examples 1, 2 and 3 is greater than that of comparative example 1, which demonstrates the effect of magnesium nitrate hexahydrate in increasing pore volume.
Thus, examples 1, 2, and 3 all showed larger specific surface area and pore volume than comparative examples, and the high specific surface area and interconnected pore structure provided a large electrode/electrolyte surface interface for charge transfer reactions, shortening the ion diffusion path, leading to enhanced rate capability during charge and discharge, indicating that the use of magnesium nitrate hexahydrate in the examples is very advantageous for preparing a carbon material rich in pores. Further, as can be seen again from the internal comparison of example 1, example 2 and example 3, example 1 shows the largest specific surface area and pore volume, indicating that magnesium nitrate hexahydrate concentration of example 1 of 0.05mol/L is more favorable for preparing a carbon material rich in pores.
Table 1 shows the mass ratios of C, N, O elements calculated by XPS test of the invention materials of example 1, example 2, example 3 and comparative example 1. It can be seen that all the examples have the existence of the N element, which proves that the nitrogen-doped carbon material is successfully prepared by the invention. The sample of example 1 had the highest N content compared to the other examples, demonstrating that the highest N doping was achieved at a magnesium nitrate hexahydrate solution concentration of 0.05 mol/L.
TABLE 1
The resulting carbon electrode material was mixed with conductive carbon black (Super P) and a binder (carboxymethyl cellulose, CMC) according to a ratio of 75: 15: 10, dropping a mixed solution of 80% of water and 20% of ethanol, fully grinding and dispersing to prepare uniform slurry, coating the uniform slurry on a copper foil, putting the copper foil into an oven at 80 ℃ for drying for 12 hours, and slicing to obtain the working electrode piece. And then, in a glove box filled with argon, taking a potassium sheet as a counter electrode, taking glass fiber as a diaphragm and taking bifluorosulfonyl imide potassium salt (KFSI) as electrolyte, and assembling a potassium ion battery by using the working electrode in the glove box. Constant current charge and discharge measurement Using LAND CT2001A model test System at Current Density of 0.05-10A g-1The voltage window is 0.001-3V, and the constant current charge-discharge cycle test is carried out at a current density of 2A g-1And (5) testing under the condition.
It can be seen from table 2, fig. 7 and fig. 8 that examples 1, 2, 3 and 1 are applied to charging in a potassium ion batteryDischarge rate capability and long cycle performance. Potassium ion batteries assembled in examples 1, 2, 3, and 1 were assembled at 2A g-1The specific capacity after 2500 cycles of circulation under the current density is 307mAh g respectively-1、194mAh g-1 、246mAh g-1、145mAh g-1The capacity retention rates were 152.3%, 137.2%, 150.6%, and 109.6%, respectively. It can be seen that examples 1, 2, and 3 all had higher specific capacity and capacity retention than the comparative example. All tests prove that the electrochemical performance of the carbon material can be enhanced by nitrogen doping, high specific surface area and uniform interconnected pore structure. In all examples, the capacity of the samples increased during cycling due to the activation of the negative electrode material during cycling.
Further, from the internal comparison among the example 1, the example 2 and the example 3, the example 1 has higher specific capacity and good rate performance and cycle stability, which indicates that the nitrogen-doped high specific surface area carbon material formed after nitrogen doping has better electrochemical performance as a potassium ion battery negative electrode when the magnesium nitrate hexahydrate concentration of the example 1 is 0.05 mol/L.
TABLE 2
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. However, the above description is only an example of the present invention, the technical features of the present invention are not limited thereto, and any other embodiments that can be obtained by those skilled in the art without departing from the technical solution of the present invention should be covered by the claims of the present invention.
Claims (10)
1. A preparation method of a nitrogen-doped porous carbon material with high specific surface area is characterized by comprising the following steps:
(1) selecting a proper biomass carbon precursor A and a proper material B which is used as an activating agent, a doping agent and a template agent in a three-in-one manner;
(2) pretreatment: preparing an aqueous solution of a material B, cutting the biomass carbon precursor A into thin slices, completely immersing the thin slices in the aqueous solution, strongly stirring, taking out, and freeze-drying to obtain a pretreated carbon precursor;
(3) carbonizing, activating and generating a template: putting the product obtained after freeze drying into a tube furnace, and carbonizing and activating at high temperature under inert atmosphere;
(4) removing and cleaning the template: and (3) cleaning the carbonized sample in dilute hydrochloric acid and deionized water to remove template particles and impurities, and then drying in an oven to finally obtain the nitrogen-doped porous carbon material with high specific surface area.
2. The method for preparing the nitrogen-doped porous carbon material with high specific surface area according to claim 1, wherein in the step (1), bacterial cellulose with the thickness of 0.3cm is selected as a carbon precursor A; selecting magnesium nitrate hexahydrate as a material B for three-in-one use of an activating agent, a doping agent and a template agent; the gases NO2 and O2 generated by the pyrolysis of magnesium nitrate hexahydrate can be activated and doped with nitrogen, and meanwhile, a magnesium oxide particle template is uniformly dispersed in a carbon matrix, has higher thermal stability and does not react with the carbon precursor at high temperature, and the obtained carbon sample containing the template can be washed away by using a diluted acid solution.
3. The method for preparing the nitrogen-doped porous carbon material with high specific surface area according to claim 1, wherein the prepared nitrogen-doped porous carbon material with high specific surface area has an interconnected pore structure mainly composed of mesopores, and the carbon layer spacing is increased by introducing a large number of active defects in the carbon matrix through nitrogen doping; the material can be applied to electrodes of potassium ion batteries; the microstructure of the material can shorten the ion transmission distance, increase the contact area of the electrode and the electrolyte, and the high specific surface area of the material can accommodate more potassium ions and relieve the volume expansion caused by the potassium ion embedding/removing process.
4. The method for preparing the nitrogen-doped porous carbon material with high specific surface area according to claim 2, wherein in the step (2), the concentration of the magnesium nitrate hexahydrate aqueous solution is 0-1 mol/L.
5. The method for preparing the nitrogen-doped porous carbon material with high specific surface area according to claim 4, wherein the concentration of the magnesium nitrate hexahydrate aqueous solution in the step (2) is 0.05 mol/L.
6. The method for preparing the nitrogen-doped porous carbon material with high specific surface area according to claim 1, wherein in the step (3), the high-temperature carbonization activation under the inert atmosphere is specifically: under inert atmosphere, heating to carbonization temperature, and keeping the temperature for a period of time; wherein the carbonization temperature is 600-1500 ℃, and the heat preservation time is 0-12 h.
7. The method for preparing the nitrogen-doped porous carbon material with high specific surface area according to claim 6, wherein in the step (3), the temperature is increased to the carbonization temperature of 800 ℃ at a temperature increase rate of 5 ℃ min-1 in an N2 atmosphere with 55 mL min-1, and the temperature is kept for 2 h.
8. The method for preparing nitrogen-doped porous carbon material with high specific surface area according to claim 1, wherein the sample carbonized in step (4) is washed in 2mol/L diluted hydrochloric acid and deionized water respectively to remove magnesium oxide particles and impurities, and more pore structures are formed.
9. The method for preparing the nitrogen-doped porous carbon material with high specific surface area according to claim 1, wherein in the step (4), the sample is dried in a vacuum drying oven at 80 ℃ for 12 hours to obtain the nitrogen-doped porous carbon material.
10. Use of a high specific surface area nitrogen doped porous carbon material prepared according to the method of any one of claims 1 to 9, characterized in that: the material is applied to the electrode of the potassium ion battery.
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| CN113548689A (en) * | 2021-07-15 | 2021-10-26 | 陕西科技大学 | Nitrogen-doped carbon/tin dioxide flexible composite film and preparation method and application thereof |
| CN113772655A (en) * | 2021-09-18 | 2021-12-10 | 河北零点新能源科技有限公司 | Heteroatom-doped hard carbon material and preparation method thereof |
| CN114068893A (en) * | 2021-10-09 | 2022-02-18 | 广东邦普循环科技有限公司 | Composite material and preparation method and application thereof |
| CN114335524A (en) * | 2022-03-15 | 2022-04-12 | 中国长江三峡集团有限公司 | Heteroatom-doped porous carbon nanobelt material and preparation method and application thereof |
| CN117163946A (en) * | 2023-11-03 | 2023-12-05 | 南通博安新材料科技有限公司 | Nitrogen-oxygen doped porous carbon and preparation method and application thereof |
| CN117163946B (en) * | 2023-11-03 | 2023-12-26 | 南通博安新材料科技有限公司 | Nitrogen-oxygen doped porous carbon and preparation method and application thereof |
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