CN113381018A - Nitrogen-fluorine atom doped three-dimensional porous carbon electrode material, preparation method and application thereof - Google Patents

Abstract

Translated fromChinese

本发明一种氮氟原子掺杂三维多孔碳的电极材料、制备方法及其应用，本发明的制备方法包括：(1)将氮源、氟源和盐模板与去离子水混合后得到混合溶液进行强磁力搅拌，再进行冷冻和冷冻真空干燥，对其产物进行刮料磨料，最后进行高温固相反应使其充分反应，得到样品；(2)将步骤(1)所述样品抽滤，真空烘干后得到活性物质，将活性物质与粘结剂PVDF和导电炭黑以及NMP溶剂混合，得到浆料涂覆到铜箔上，获得负极；(3)将步骤(2)所述负极在真空下进行烘干，进行裁片并在手套箱中配制电解液，装电池，并在电池制备完成后测试性能；本发明提供的氮氟原子掺杂三维多孔碳的电极材料导电性好，比容量高，倍率性能和循环性能好。

The present invention is a nitrogen-fluorine atom-doped three-dimensional porous carbon electrode material, a preparation method and an application thereof. The preparation method of the present invention includes: (1) mixing a nitrogen source, a fluorine source and a salt template with deionized water to obtain a mixed solution Carry out strong magnetic stirring, then freeze and freeze-vacuum drying, scrape and grind the product, and finally carry out high-temperature solid-phase reaction to make it fully react to obtain a sample; (2) filter the sample described in step (1), vacuum After drying, the active material is obtained, and the active material is mixed with the binder PVDF, conductive carbon black and NMP solvent to obtain a slurry that is coated on the copper foil to obtain a negative electrode; (3) the negative electrode in step (2) is placed in a vacuum Drying under low temperature, cutting pieces, preparing electrolyte in a glove box, installing a battery, and testing the performance after the battery is prepared; the electrode material of the nitrogen-fluorine atom-doped three-dimensional porous carbon provided by the present invention has good conductivity and a specific capacity. high, good rate performance and cycle performance.

Description

Nitrogen-fluorine atom doped three-dimensional porous carbon electrode material, preparation method and application thereof

Technical Field

The invention relates to the technical field of new energy materials, in particular to an electrode material of nitrogen and fluorine atom doped three-dimensional porous carbon, a preparation method and application thereof.

Background

The lithium ion battery has the advantages of high energy density, light weight, small volume, good cycle performance, environmental friendliness, no memory effect and the like, and is widely applied to various fields of electronic products, electric automobiles, large-scale energy storage and the like. However, the problems of shortage and uneven distribution of lithium resources in the earth crust are not enough to meet the increasing demand of people on the lithium ion battery, which seriously restricts the large-scale application of the lithium ion battery. Therefore, development of a novel secondary battery with abundant resources, low cost and excellent performance has become a new development trend and a research hotspot in the field of battery materials.

In recent years, sodium and potassium ion batteries have attracted extensive attention by researchers, and are considered to be ideal candidates for replacing lithium ion batteries as next-generation energy storage power sources because sodium, potassium and lithium belong to the same main group elements and have similar physicochemical properties. Meanwhile, the sodium and potassium elements are widely distributed, the resources are rich, the price is low, and the like, so that the method is more in line with the requirements of large-scale energy storage application. Therefore, sodium/potassium ion batteries have also received much attention from many researchers as new energy storage devices. However, since the radius of both sodium and potassium ions is larger than that of lithium ions, the requirements for an electrode material capable of freely extracting sodium and potassium ions are more severe. When the traditional graphite cathode is used as the cathode of the sodium-ion battery, the specific capacity is lower when sodium ions are inserted and removed, and the development of the sodium-ion battery is severely restricted. Although the traditional graphite negative electrode can reversibly remove and insert potassium ions, the theoretical specific capacity of the graphite negative electrode as a negative electrode of a potassium ion battery is only 279 mAh/g. Therefore, research and development of a new sodium and potassium ion battery anode material are very important.

Nitrogen was first believed to exist in two forms in carbon materials, referred to as chemical nitrogen and lattice nitrogen, respectively. The former is likely to undergo an irreversible reaction with lithium and increase the irreversible capacity, and therefore, a carbon material doped with a nitrogen atom is considered to be unsuitable as a negative electrode material for a lithium ion battery. However, the same chemical vapor deposition method and the same raw material (pyridine) gave different results. The charge and discharge results show that the reversible capacity increases with the increase of the complex content and exceeds the theoretical capacity of graphite. In the polymer cracking carbon, the reversible capacity of the carbon material is increased along with the increase of the nitrogen content, and the carbon material has the advantages of high theoretical specific capacity, high chemical stability, high conductivity, low cost, small polarization in the charging and discharging process and the like.

Disclosure of Invention

The invention aims to solve the problems that: the electrode material of the nitrogen-fluorine atom doped three-dimensional porous carbon has high conductivity, high specific capacity, good cycle and rate performance, cheap and easily-obtained raw materials, simple preparation process and strong operation controllability.

The technical scheme provided by the invention for solving the problems is as follows: an electrode material of three-dimensional porous carbon doped with nitrogen and fluorine atoms, the electrode material comprises a carbon material matrix and the nitrogen and fluorine atoms doped in the carbon material, wherein the specific surface area of the electrode material is 280m²(ii)/g; the carbon-based material is three-dimensional porous carbon.

The invention also discloses a preparation method of the electrode material of the nitrogen and fluorine atom doped three-dimensional porous carbon, which comprises the following steps:

(1) mixing a nitrogen source, a fluorine source, a dissolved salt template and deionized water to obtain a mixed solution, stirring the mixed solution by strong magnetic force, freezing and freeze-vacuum drying the mixed solution, scraping and grinding the product, and finally carrying out high-temperature solid-phase reaction to fully react the product to obtain a sample;

(2) carrying out suction filtration on the sample obtained in the step (1), drying in vacuum to obtain an active substance, mixing the active substance with a binder PVDF, conductive carbon black and an NMP solvent to obtain slurry, and coating the slurry on a copper foil to obtain a negative electrode;

(3) and (3) cutting the negative electrode in the step (2), assembling the battery, and testing electrochemical performance after the battery is prepared.

Preferably, the dissolved salt template in the step (1) is sodium chloride; the nitrogen source and the fluorine source are ammonium fluoride; the carbon is citric acid.

Preferably, in the mixed solution in the step (1), the concentration of sodium chloride is 20-30 wt%; the concentration of ammonium fluoride is 0.1-1 mol/L; the concentration of ammonium citrate is 0.1-0.2 mol/L.

Preferably, the stirring time of the step (1) is 12 hours; the freezing time is 36-72 hours; the high-temperature solid-phase reaction temperature is 500-750 ℃; the reaction time is 2-5 hours.

Preferably, the freeze-drying in step (1) is carried out in a freeze-dryer; the step (1) further comprises the step of putting the mixed solution obtained in the step (1) into a freezing layer of a refrigerator for freezing for 36-72 hours to obtain a solid mixture; in addition, the step (1) further comprises the step of putting the solid mixture in the refrigerator into a freeze-drying instrument, and freeze-drying for 24-72 hours in a vacuum low-temperature environment.

Preferably, the high-temperature solid-phase reaction in the step (1) is carried out in a tubular atmosphere furnace; the protective atmosphere is argon; the step (1) also comprises the step of keeping the temperature at 65 ℃ for 60 minutes; the step (1) further comprises a step of putting the mixed solid obtained in the step (1) into a mortar and sufficiently grinding the mixed solid.

Preferably, in the step (1), the suction filtration is carried out for multiple times, wherein the suction filtration times are 3-5 times.

Preferably, the method comprises in particular the steps of,

(1) introducing protective atmosphere into a tubular atmosphere furnace, heating the tubular atmosphere furnace at normal temperature to 600-750 ℃ at the speed of 6-20 ℃ per minute, keeping the temperature at 600-750 ℃ for 120-300 minutes, stopping heating, and waiting for natural cooling to obtain a fluorine-nitrogen-doped carbon material precursor containing a dissolved salt template;

(2) mixing the fluorine-nitrogen doped carbon material precursor with more than 200ml of free water, and stirring for 5-10 minutes by using a magnetic stirrer to obtain a solid-liquid mixture; pouring the solid-liquid mixture obtained in the step into a suction filtration instrument for suction filtration; repeating the process for 3-5 times, drying in a common drying oven, and drying in a vacuum drying oven to obtain the fluorine-nitrogen doped carbon material of claim 1.

The invention also discloses application of the electrode material of the three-dimensional porous carbon doped with the nitrogen and fluorine atoms as claimed in claim 1, wherein the electrode material of the three-dimensional porous carbon doped with the nitrogen and fluorine atoms is used as a negative electrode material and acts on a potassium ion battery.

Compared with the prior art, the invention has the advantages that:

(1) the nitrogen-fluorine/three-dimensional porous carbon composite material provided by the invention has the advantages of good conductivity, high specific capacity, good rate capability and cycle performance, and is particularly suitable for being used as a negative electrode material for a potassium ion battery. The nitrogen-fluorine/three-dimensional porous carbon composite material provided by the invention is used for a potassium ion battery, the first charge specific capacity of 50mA/g can reach 366.7mAh/g, the discharge specific capacity of 500mA/g can reach 301.2mAh/g, the conductivity can reach 6.8 multiplied by 10 < -4 > S/m, and the capacity retention rate after 50 charge-discharge cycles under 50mA/g can reach 80.1%;

(2) the preparation method provided by the invention adopts a high-temperature solid phase method to prepare the nitrogen-fluorine/three-dimensional porous carbon composite material, the raw materials are cheap and easy to obtain, the preparation process is simple, the operation controllability is strong, and the preparation method is suitable for industrial large-scale production.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is an SEM image of a N-fluoro/three-dimensional porous carbon composite material prepared in example 1 of the present invention;

FIG. 2 is a cycle performance test chart of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in example 1 of the present invention as a negative electrode material of a potassium ion battery under the conditions of a voltage interval of 0.01-3.0V and a current density of 200 mA/g;

fig. 3 is a graph of rate performance of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in example 1 of the present invention as a negative electrode material of a potassium ion battery under different current densities within a voltage range of 0.01 to 3.0V.

Detailed Description

The embodiments of the present invention will be described in detail with reference to the accompanying drawings and examples, so that how to implement the technical means for solving the technical problems and achieving the technical effects of the present invention can be fully understood and implemented.

Example 1

This example prepares a niff/three-dimensional porous carbon composite material as follows:

(1) 2.4999g of citric acid, 20.6500g of sodium chloride and 0.3333g of ammonium fluoride were added to 80ml of deionized water and stirred strongly. Freezing the obtained solution for 36-72 h, drying the solution in a freeze dryer at-42-50 ℃ for 24-36 h, scraping the sample after the drying is finished, putting the sample into a tubular atmosphere furnace for high-temperature solid-phase reaction, and keeping the temperature at 600 ℃ at the heating rate of 5 ℃/min for 8h to obtain a sample;

(2) carrying out suction filtration on the sample in the step (1) for 3 times and drying for 6 hours to obtain an active substance, mixing 0.14g of the active substance with 0.04g of acetylene black and 0.40g of PVDF (polyvinylidene fluoride) binder, and finally adding 10ml of NMP (N-methyl pyrrolidone) solvent and carrying out strong magnetic stirring;

wherein the content of the binder PVDF is 5%, and the mass ratio of the active substance to the acetylene black to the binder PVDF is 7:2: 1;

(3) coating and cutting the negative electrode coating material obtained in the step (2), mixing 2.2087g of potassium hexafluorophosphate, 9.9135g of ethylene carbonate and 7.3125g of diethyl carbonate in a glove box to obtain electrolyte, preparing a button type potassium ion battery, and finally testing the performance of the button type potassium ion battery;

the appearance structure characterization of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in the embodiment is performed by using a Scanning Electron Microscope (SEM), and the pore structure characterization is performed by using a full-automatic multifunctional gas adsorption instrument, and the results are as follows;

the composite material prepared by the embodiment comprises a carbon material substrate and nitrogen, fluorine and three-dimensional porous carbon composite materials embedded in the carbon material substrate

The electrochemical performance test results of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in the embodiment are shown in table 1.

Fig. 1 is an SEM image of the niff/three-dimensional porous carbon composite material prepared in this example, from which analysis revealed that the active material was present.

Fig. 2 is a cycle performance test chart of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in this example as a negative electrode material of a potassium ion battery (the specific method for preparing the potassium ion battery refers to an electrochemical performance test part) under the conditions of a voltage interval and a current density of 200mA/g, and it can be seen from the chart that, at 25 ℃, charge and discharge cycles are performed at a current density of 200mA/g in a voltage range of 0.1 to 3V, the first discharge capacity of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in this example is 613.2mAh/g, the charge capacity is 237.7mAh/g, and the reversible specific capacity after 500 cycles is 220.9mAh/g, which shows excellent cycle stability;

fig. 3 shows that when the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in this embodiment is used as a potassium ion battery negative electrode material (a specific method for preparing a potassium ion battery refers to an electrochemical performance test part), reversible specific capacities of the nitrogen-fluorine/three-dimensional porous carbon composite material are 259.8, 230.6, 204.5, 183.6 and 134.5mAh/g respectively at different current densities of 100-2000mA/g, and when the current density returns to 50mA/g, the specific capacity can still reach 224.2mAh/g, which shows excellent rate capability.

Example 2

This example prepares a niff/three-dimensional porous carbon composite material as follows:

(1) 2.4999g of citric acid, 20.6500g of sodium chloride and 0.6666g of ammonium fluoride were added to 80ml of deionized water and stirred strongly. Freezing the obtained solution for 36-72 h, drying the solution in a freeze dryer at-42-50 ℃ for 24-36 h, scraping the sample after the drying is finished, putting the sample into a tubular atmosphere furnace for high-temperature solid-phase reaction, and keeping the temperature at 600 ℃ at the heating rate of 5 ℃/min for 8h to obtain a sample;

(2) carrying out suction filtration on the sample in the step (1) for 3 times and vacuum drying for 6 hours to obtain an active substance, mixing 0.14g of the active substance with 0.04g of acetylene black and 0.40g of PVDF (polyvinylidene fluoride) binder, and finally adding 10ml of NMP (N-methyl pyrrolidone) solvent and carrying out strong magnetic stirring;

wherein the content of the binder PVDF is 5%, and the mass ratio of the active substance to the acetylene black to the binder PVDF is 7:2: 1;

(3) coating and cutting the negative electrode coating material obtained in the step (2), mixing 2.2087g of potassium hexafluorophosphate, 9.9135g of ethylene carbonate and 7.3125g of diethyl carbonate in a glove box to obtain electrolyte, preparing a button type potassium ion battery, and finally testing the performance of the button type potassium ion battery;

the electrochemical performance test results of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in the embodiment are shown in tables 1 and 2.

Example 3

This example prepares a niff/three-dimensional porous carbon composite material as follows:

(1) 2.4999g of citric acid, 20.6500g of sodium chloride and 1.0000g of ammonium fluoride were added to 80ml of deionized water and stirred strongly. Freezing the obtained solution for 36-72 h, drying the solution in a freeze dryer for 24-36 h under the condition of 42-50 ℃ below zero, scraping and grinding the sample, putting the sample into a tubular atmosphere furnace for high-temperature solid-phase reaction, and keeping the temperature at 650 ℃ at the heating rate of 5 ℃/min for 8h to obtain the sample;

(2) carrying out suction filtration on the sample in the step (1) for 3 times and vacuum drying for 6 hours to obtain an active substance, mixing 0.14g of the active substance with 0.04g of acetylene black and 0.40g of PVDF (polyvinylidene fluoride) binder, and finally adding 10ml of NMP (N-methyl pyrrolidone) solvent and carrying out strong magnetic stirring;

wherein the content of the binder PVDF is 5%, and the mass ratio of the active substance to the acetylene black to the binder PVDF is 7:2: 1;

(3) coating and cutting the negative electrode coating material obtained in the step (2), mixing 2.2087g of potassium hexafluorophosphate, 9.9135g of ethylene carbonate and 7.3125g of diethyl carbonate in a glove box to obtain an electrolyte, preparing a potassium battery, and finally testing the performance of the potassium battery;

the electrochemical performance test results of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in the embodiment are shown in table 1.

Example 4

This example prepares a phosphorus/three-dimensional porous carbon composite as follows:

2.4999g of citric acid, 20.6500g of sodium chloride and 1.2751g of ammonium fluoride were added to 80ml of deionized water and stirred strongly. Freezing the obtained solution for 36-72 h, drying the solution in a freeze dryer for 24-36 h under the condition of 42-50 ℃ below zero, scraping and grinding the sample, putting the sample into a tubular atmosphere furnace for high-temperature solid-phase reaction, and keeping the temperature at 600 ℃ at the heating rate of 5 ℃/min for 8h to obtain the sample;

(2) carrying out suction filtration on the sample in the step (1) for 3 times and vacuum drying for 6 hours to obtain an active substance, mixing 0.14g of the active substance with 0.04g of acetylene black and 0.40g of PVDF (polyvinylidene fluoride) binder, and finally adding 10ml of NMP (N-methyl pyrrolidone) solvent and carrying out strong magnetic stirring;

wherein the content of the binder PVDF is 5%, and the mass ratio of the active substance to the acetylene black to the binder PVDF is 7:2: 1;

(3) coating and cutting the negative electrode coating material obtained in the step (2), mixing 2.2087g of potassium hexafluorophosphate, 9.9135g of ethylene carbonate and 7.3125g of diethyl carbonate in a glove box to obtain an electrolyte, preparing a potassium battery, and finally testing the performance of the potassium battery;

the electrochemical performance test results of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in the embodiment are shown in table 1.

Example 5

This example prepares a phosphorus/three-dimensional porous carbon composite as follows:

2.49999556g of citric acid, 20.6500078g of sodium chloride and 2.550352g of ammonium fluoride were added to 80ml of deionized water and stirred strongly. Freezing the obtained solution for 36-72 h, drying the solution in a freeze dryer for 24-36 h under the condition of 42-50 ℃ below zero, scraping and grinding the sample, putting the sample into a tubular atmosphere furnace for high-temperature solid-phase reaction, and keeping the temperature at 600 ℃ at the heating rate of 5 ℃/min for 8h to obtain the sample;

wherein the mass ratio of the phosphorus source to the carbon source is 2: 1;

(2) carrying out suction filtration on the sample in the step (1) for 3 times and vacuum drying for 6 hours to obtain an active substance, mixing 0.14g of the active substance with 0.04g of acetylene black and 0.40g of PVDF (polyvinylidene fluoride) binder, and finally adding 10ml of NMP (N-methyl pyrrolidone) solvent and carrying out strong magnetic stirring;

wherein the content of the binder PVDF is 5%, and the mass ratio of the active substance to the acetylene black to the binder PVDF is 7:2: 1;

(3) coating and cutting the negative electrode coating material obtained in the step (2), mixing 2.2087g of potassium hexafluorophosphate, 9.9135g of ethylene carbonate and 7.3125g of diethyl carbonate in a glove box to obtain an electrolyte, preparing a potassium battery, and finally testing the performance of the potassium battery;

the electrochemical performance test results of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in the embodiment are shown in tables 1 and 2.

Example 6

This example prepares a phosphorus/three-dimensional porous carbon composite as follows:

2.4999g of citric acid, 20.6500g of sodium chloride and 3.8255g of ammonium fluoride were added to 80ml of deionized water and stirred strongly. Freezing the obtained solution for 36-72 h, drying the solution in a freeze dryer for 24-36 h under the condition of 42-50 ℃ below zero, scraping and grinding the sample, putting the sample into a tubular atmosphere furnace for high-temperature solid-phase reaction, and keeping the temperature at 600 ℃ at the heating rate of 5 ℃/min for 8h to obtain the sample;

wherein the mass ratio of the nitrogen-fluorine source to the carbon source is 3: 1;

(2) carrying out suction filtration on the sample in the step (1) for 3 times and vacuum drying for 6 hours to obtain an active substance, mixing 0.14g of the active substance with 0.04g of acetylene black and 0.40g of PVDF (polyvinylidene fluoride) binder, finally adding 30 drops of NMP (N-methyl pyrrolidone) solvent, and carrying out strong magnetic stirring;

wherein the content of the binder PVDF is 5%, and the mass ratio of the active substance to the acetylene black to the binder PVDF is 7:2: 1;

(3) coating and cutting the negative electrode coating material obtained in the step (2), mixing 2.2087g of potassium hexafluorophosphate, 9.9135g of ethylene carbonate and 7.3125g of diethyl carbonate in a glove box to obtain an electrolyte, preparing a potassium battery, and finally testing the performance of the potassium battery;

the electrochemical performance test results of the nitrogen-fluorine/three-dimensional porous carbon composite material prepared in the embodiment are shown in table 1.

TABLE 1 electrochemical Performance test results of Nitrogen-fluorine/three-dimensional porous carbon composite materials prepared under different conditions

According to the embodiment and the comparative example, the structure of the nitrogen-fluorine/three-dimensional porous carbon composite material obtained by a dissolved salt template method and a high-temperature solid phase method is unique, so that the circulation stability of the composite material is improved; on the other hand, the synergistic effect between carbon and phosphide improves the specific capacity and rate capability of the composite material. Such unique results enable the present invention to provide

The nitrogen-fluorine/three-dimensional porous carbon composite material has the advantages of unique structure, good conductivity, high specific capacity, good rate capability and good cycle performance, and is particularly suitable for being used as a negative electrode material for sodium ion batteries or potassium ion batteries.

The foregoing is merely illustrative of the preferred embodiments of the present invention and is not to be construed as limiting the claims. The present invention is not limited to the above embodiments, and the specific structure thereof is allowed to vary. All changes which come within the scope of the invention as defined by the independent claims are intended to be embraced therein.

Claims (10)

1. The electrode material of the three-dimensional porous carbon doped with nitrogen and fluorine atoms is characterized in that: the electrode material comprises a carbon material matrix and a carbon material doped with the carbon material matrixNitrogen and fluorine atoms of the material, wherein the specific surface area of the electrode material is 280m²(ii)/g; the carbon-based material is three-dimensional porous carbon.

2. A method for preparing the electrode material of nitrogen-fluorine atom-doped three-dimensional porous carbon according to claim 1, characterized in that: the method comprises the following steps:

(1) mixing a nitrogen source, a fluorine source, a dissolved salt template and deionized water to obtain a mixed solution, stirring the mixed solution by strong magnetic force, freezing and freeze-vacuum drying the mixed solution, scraping and grinding the product, and finally carrying out high-temperature solid-phase reaction to fully react the product to obtain a sample;

(2) carrying out suction filtration on the sample obtained in the step (1), drying in vacuum to obtain an active substance, mixing the active substance with a binder PVDF, conductive carbon black and an NMP solvent to obtain slurry, and coating the slurry on a copper foil to obtain a negative electrode;

(3) and (3) cutting the negative electrode in the step (2), assembling the battery, and testing electrochemical performance after the battery is prepared.

3. The method for preparing an electrode material of nitrogen-fluorine atom-doped three-dimensional porous carbon according to claim 2, characterized in that: the salt dissolving template in the step (1) is sodium chloride; the nitrogen source and the fluorine source are ammonium fluoride; the carbon is citric acid.

4. The method for preparing an electrode material of nitrogen-fluorine atom-doped three-dimensional porous carbon according to claim 3, characterized in that: in the mixed solution in the step (1), the concentration of sodium chloride is 20-30 wt%; the concentration of ammonium fluoride is 0.1-1 mol/L; the concentration of ammonium citrate is 0.1-0.2 mol/L.

5. The method for preparing an electrode material of nitrogen-fluorine atom-doped three-dimensional porous carbon according to claim 2, characterized in that: the stirring time in the step (1) is 12 hours; the freezing time is 36-72 hours; the high-temperature solid-phase reaction temperature is 500-750 ℃; the reaction time is 2-5 hours.

6. The method for preparing an electrode material of nitrogen-fluorine atom-doped three-dimensional porous carbon according to claim 2, characterized in that: in the step (1), freeze drying is carried out in a freeze dryer; the step (1) further comprises the step of putting the mixed solution obtained in the step (1) into a freezing layer of a refrigerator for freezing for 36-72 hours to obtain a solid mixture; in addition, the step (1) further comprises the step of putting the solid mixture in the refrigerator into a freeze-drying instrument, and freeze-drying for 24-72 hours in a vacuum low-temperature environment.

7. The method for preparing an electrode material of nitrogen-fluorine atom-doped three-dimensional porous carbon according to claim 2, characterized in that: the high-temperature solid-phase reaction in the step (1) is carried out in a tubular atmosphere furnace; the protective atmosphere is argon; the step (1) also comprises the step of keeping the temperature at 65 ℃ for 60 minutes; the step (1) further comprises a step of putting the mixed solid obtained in the step (1) into a mortar and sufficiently grinding the mixed solid.

8. The method for preparing an electrode material of nitrogen-fluorine atom-doped three-dimensional porous carbon according to claim 2, characterized in that: and (2) performing suction filtration for many times in the step (1), wherein the suction filtration times are 3-5 times.

9. The method for preparing an electrode material of nitrogen-fluorine atom-doped three-dimensional porous carbon according to claim 2, characterized in that: the method comprises in particular the following steps,

(1) introducing protective atmosphere into a tubular atmosphere furnace, heating the tubular atmosphere furnace at normal temperature to 600-750 ℃ at the speed of 6-20 ℃ per minute, keeping the temperature at 600-750 ℃ for 120-300 minutes, stopping heating, and waiting for natural cooling to obtain a fluorine-nitrogen-doped carbon material precursor containing a dissolved salt template;

(2) mixing the fluorine-nitrogen doped carbon material precursor with more than 200ml of free water, and stirring for 5-10 minutes by using a magnetic stirrer to obtain a solid-liquid mixture; pouring the solid-liquid mixture obtained in the step into a suction filtration instrument for suction filtration; repeating the process for 3-5 times, drying in a common drying oven, and drying in a vacuum drying oven to obtain the fluorine-nitrogen doped carbon material of claim 1.

10. Use of the electrode material of nitrogen-fluorine atom doped three-dimensional porous carbon according to claim 1, wherein: the electrode material of the nitrogen and fluorine atom doped three-dimensional porous carbon is used as a negative electrode material and acts on the potassium ion battery.

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