1. The preparation method of the nitrogen-doped porous lamellar carbon is characterized by comprising the following steps of: and mixing and heating the nitrogen-containing compound, the chloride, the active additive and the carbon source until the mixture is melted together, and calcining the mixture in a protective atmosphere to obtain the nitrogen-doped porous lamellar carbon.

2. The method of preparing nitrogen-doped porous lamellar carbon according to claim 1, characterized in that: the molar ratio of the nitrogen-containing compound to the chloride to the active additive to the carbon source is 4:6: 0-0.15: 0.4.

3. The method for producing nitrogen-doped porous lamellar carbon according to claim 1 or 2, characterized in that: the nitrogen-containing compound is at least one of urea and thiourea.

4. The method for producing nitrogen-doped porous lamellar carbon according to claim 1 or 2, characterized in that: the chloride is MgCl₂。

5. The method for producing nitrogen-doped porous lamellar carbon according to claim 1 or 2, characterized in that: the active additive is FeCl₃、ZnCl₂At least one of (1).

6. The method for producing nitrogen-doped porous lamellar carbon according to claim 1 or 2, characterized in that: the carbon source is at least one of sucrose, glucose and fructose.

7. The method for producing nitrogen-doped porous lamellar carbon according to claim 1 or 2, characterized in that: the heating is carried out at 70-90 ℃ for 30-50 min.

8. The method for producing nitrogen-doped porous lamellar carbon according to claim 1 or 2, characterized in that: the calcination is carried out at 650-800 ℃, and the heat preservation time is 1-3 h.

9. A nitrogen-doped porous lamellar carbon, characterized in that it is prepared by the method of any one of claims 1 to 8.

10. Use of the nitrogen-doped porous lamellar carbon of claim 9 in the preparation of a lithium ion capacitor.

Background

With the rapid development of new energy industries represented by electric vehicles, wind power generation and tidal power generation, the demand of people for high-performance energy storage devices is rapidly increasing. The lithium ion capacitor is a novel energy storage device, has the advantages of high power density of the super capacitor and high energy density of the lithium ion battery, and is widely concerned by the industry and researchers. However, the relatively low energy density of lithium ion capacitors (compared to lithium ion batteries) limits their applications and developments, and improving the performance of electrode materials is one of the main approaches to increasing the energy density of lithium ion capacitors.

The carbon material has good chemical stability, structural plasticity and electrical conductivity, and is an ideal electrode material of the lithium ion capacitor. Furthermore, the performance of carbon electrode materials can be further improved by doping carbon materials with heteroatoms (e.g., B, N, P, O, etc.), so the development of heteroatom-doped carbon materials has become a hot research point in the field of lithium ion capacitors today.

Nitrogen-doped carbon materials are heteroatom-doped carbon materials that have been studied for comparative heats in recent years, for example: xu Yanan et al uses Mg powder as template, polypyrrole nano-fiber as buffer, and Mg and CO as raw materials₂The porous nitrogen-doped carbon material (adv. mater.2020,2005531) is prepared by the redox reaction through a vapor deposition method; the Yang Yuqi takes reduced graphene oxide as a carbon source, takes hydrazine hydrate and dopamine as a nitrogen source, and prepares the polydopamine graphene material by a one-step method. However, nitrogen-doped carbon materials have been difficult to commercially produce due to: in the traditional method, impregnation dispersion and activation operation of a strong alkaline activator are required in the process of preparing the carbon material, so that the problems of long time consumption, high energy consumption, high pollution and the like exist, the yield of the carbon material is low, and the price of the carbon material is high.

Disclosure of Invention

The invention aims to provide nitrogen-doped porous lamellar carbon and a preparation method and application thereof.

The technical scheme adopted by the invention is as follows:

the preparation method of the nitrogen-doped porous lamellar carbon comprises the following steps: and mixing and heating the nitrogen-containing compound, the chloride, the active additive and the carbon source until the mixture is melted together, and calcining the mixture in a protective atmosphere to obtain the nitrogen-doped porous lamellar carbon.

Preferably, the preparation method of the nitrogen-doped porous lamellar carbon comprises the following steps: mixing and heating a nitrogen-containing compound, a chloride, an active additive and a carbon source until the nitrogen-containing compound, the chloride, the active additive and the carbon source are molten together, calcining the mixture in a protective atmosphere, and grinding, washing and drying a product obtained by calcining the mixture to obtain the nitrogen-doped porous lamellar carbon.

Preferably, the molar ratio of the nitrogen-containing compound to the chloride to the active additive to the carbon source is 4:6: 0-0.15: 0.4.

Preferably, the nitrogen-containing compound is at least one of urea and thiourea.

Preferably, the chloride is MgCl₂。

Further preferably, the chloride is MgCl₂·6H₂O。

Preferably, the active additive is FeCl₃、ZnCl₂At least one of (1).

Preferably, the carbon source is at least one of sucrose, glucose and fructose.

Preferably, the heating is carried out at 70-90 ℃ for 30-50 min.

Preferably, the calcination is carried out at 650-800 ℃, and the heat preservation time is 1-3 h.

Preferably, the protective atmosphere is a nitrogen atmosphere or an argon atmosphere.

The invention has the beneficial effects that: the nitrogen-doped porous lamellar carbon has excellent electrochemical performance, simple preparation process, controllable reaction, cleanness, environmental protection and low cost, and has good industrial application prospect.

Specifically, the method comprises the following steps:

1) the method has the advantages that the raw materials are mixed and heated to be fused together and then calcined, the operation is simple, the time is short, the full mixing of the activating agent and the carbon source is realized without adopting an impregnation method, the operation is greatly simplified, the time is saved, and the energy consumption is reduced;

2) according to the method, the nitrogen-doped porous lamellar carbon is prepared by directly pyrolyzing the precursor by a one-pot method, and the raw materials do not need to be pre-carbonized, so that the steps are simplified, and the time and the energy are saved;

3) the liquid eutectic precursor is beneficial to industrialized pipeline transportation, and has advantages in industrialized production.

Drawings

FIG. 1 is an SEM image of nitrogen-doped porous lamellar carbon in examples 1-4.

FIG. 2 is an XRD pattern of nitrogen-doped porous lamellar carbon in examples 1-4.

FIG. 3 is a graph showing nitrogen adsorption-desorption curves of nitrogen-doped porous lamellar carbon in examples 1 to 4.

FIG. 4 is a graph of rate capability of the lithium ion capacitor cathode material prepared from the nitrogen-doped porous lamellar carbon in examples 1-4.

Fig. 5 is a graph of cycle performance of the lithium ion capacitor cathode material prepared from nitrogen-doped porous lamellar carbon in example 4.

Detailed Description

The invention will be further explained and illustrated with reference to specific examples.

Example 1:

a preparation method of nitrogen-doped porous lamellar carbon comprises the following steps:

2.4g (0.04mol) of urea, 12.19g (0.06mol) of MgCl₂·6H₂Adding O and 1.368g (0.004mol) of cane sugar into a 50mL round-bottom flask, heating for 40min in an 80 ℃ oil bath to form a uniform liquid eutectic substance, then placing the liquid eutectic substance into a porcelain boat, transferring the porcelain boat into a tube furnace, introducing nitrogen, heating to 800 ℃ at the speed of 5 ℃/min, preserving heat for 2h, naturally cooling to 100 ℃, grinding a calcined product, then adding the calcined product into a 100mL beaker, adding 50mL of hydrochloric acid with the concentration of 0.5mol/L, magnetically stirring for 6h at normal temperature, carrying out suction filtration, washing the filtered solid with water until the pH of the filtrate is 7, and then placing the beaker in a vacuum drying oven for drying overnight at 50 ℃ to obtain the nitrogen-doped porous sheet carbon.

Example 2:

a preparation method of nitrogen-doped porous lamellar carbon comprises the following steps:

2.4g (0.04mol) of urea, 12.19g (0.06mol) of MgCl₂·6H₂O, 0.811g (0.0005mol) FeCl₃Adding 1.368g (0.004mol) of sucrose into a 50mL round-bottom flask, heating in an oil bath at 80 ℃ for 40min to form a uniform liquid eutectic, placing the liquid eutectic into a porcelain boat, transferring the porcelain boat into a tube furnace, introducing nitrogen, heating to 800 ℃ at the speed of 5 ℃/min, preserving heat for 2h, and naturally cooling to 10%And grinding the calcined product at 0 ℃, adding the ground product into a 100mL beaker, adding 50mL of hydrochloric acid with the concentration of 0.5mol/L, magnetically stirring for 6 hours at normal temperature, carrying out suction filtration, washing the filtered solid with water until the pH value of the filtrate is 7, and then placing the filtrate in a vacuum drying oven for drying overnight at 50 ℃ to obtain the nitrogen-doped porous lamellar carbon.

Example 3:

a preparation method of nitrogen-doped porous lamellar carbon comprises the following steps:

2.4g (0.04mol) of urea, 12.19g (0.06mol) of MgCl₂·6H₂O, 1.622g (0.001mol) FeCl₃And adding 1.368g (0.004mol) of sucrose into a 50mL round-bottom flask, heating for 40min in an 80 ℃ oil bath to form a uniform liquid eutectic substance, placing the liquid eutectic substance into a porcelain boat, transferring the porcelain boat into a tube furnace, introducing nitrogen, heating to 800 ℃ at the speed of 5 ℃/min, preserving heat for 2h, naturally cooling to 100 ℃, grinding a calcined product, adding the calcined product into a 100mL beaker, adding 50mL of hydrochloric acid with the concentration of 0.5mol/L, magnetically stirring for 6h at normal temperature, carrying out suction filtration, washing the filtered solid with water until the pH of the filtrate is 7, and drying overnight at 50 ℃ in a vacuum drying oven to obtain the nitrogen-doped porous lamellar carbon.

Example 4:

a preparation method of nitrogen-doped porous lamellar carbon comprises the following steps:

2.4g (0.04mol) of urea, 12.19g (0.06mol) of MgCl₂·6H₂O, 2.433g (0.0015mol) FeCl₃And adding 1.368g (0.004mol) of sucrose into a 50mL round-bottom flask, heating for 40min in an 80 ℃ oil bath to form a uniform liquid eutectic substance, placing the liquid eutectic substance into a porcelain boat, transferring the porcelain boat into a tube furnace, introducing nitrogen, heating to 800 ℃ at the speed of 5 ℃/min, preserving heat for 2h, naturally cooling to 100 ℃, grinding a calcined product, adding the calcined product into a 100mL beaker, adding 50mL of hydrochloric acid with the concentration of 0.5mol/L, magnetically stirring for 6h at normal temperature, carrying out suction filtration, washing the filtered solid with water until the pH of the filtrate is 7, and drying overnight at 50 ℃ in a vacuum drying oven to obtain the nitrogen-doped porous lamellar carbon.

And (3) performance testing:

1) scanning Electron Microscope (SEM) images and X-ray diffraction (XRD) images of the nitrogen-doped porous lamellar carbon of examples 1 to 4 are shown in fig. 1 and fig. 2, respectively.

As can be seen from fig. 1: using MgCl₂·6H₂The O is used as a template agent to prepare the carbon material with a lamellar structure, and the dispersion degree of the lamellar structure of the carbon material is improved along with the increase of the addition amount of the active additive, namely the lamellar structure of the material can be adjusted by adjusting the addition amount of the active additive.

As can be seen from fig. 2: as the amount of the active additive added increases, the (002) peak of carbon shifts to a small angle and the lattice spacing increases.

2) The nitrogen adsorption-desorption curves of the nitrogen-doped porous lamellar carbons of examples 1 to 4 are shown in FIG. 3.

As can be seen from fig. 3: the specific surface area and the pore structure of the nitrogen-doped porous lamellar carbon can be adjusted by adjusting the addition amount of the active additive, the specific surface area of the nitrogen-doped porous lamellar carbon is increased along with the increase of the addition amount of the active additive, and the proportion of macropores is increased.

3) The rate performance graph of the lithium ion capacitor cathode material prepared from the nitrogen-doped porous lamellar carbon in examples 1-4 is shown in fig. 4.

As can be seen from fig. 4: the nitrogen-doped porous lamellar carbon is used as the anode material of the lithium ion capacitor, has the discharge specific capacity of 97.25mAh/g (the current density is 0.25A/g), has the discharge specific capacity of 58mAh/g when the current density is 10A/g, and shows good rate capability.

4) The cycle performance (8000 cycles) of the lithium ion capacitor cathode material prepared from the nitrogen-doped porous lamellar carbon in example 4 is shown in fig. 5.

As can be seen from fig. 5: the retention rate of the discharge specific capacity of the nitrogen-doped porous lamellar carbon serving as the anode material of the lithium ion capacitor after 8000 cycles can still reach 94%, and the excellent cycle performance is shown.

5) The results of the nitrogen content, specific surface area, total pore volume and micropore volume tests on the nitrogen-doped porous lamellar carbon in examples 1-4 are shown in the following table:

TABLE 1 Nitrogen content, specific surface area, Total pore volume and micropore volume test results for Nitrogen-doped porous lamellar carbon

As can be seen from Table 1: by adjusting the active additive FeCl₃The specific surface area and the nitrogen element content of the nitrogen-doped porous lamellar carbon can be adjusted according to the proportion of the nitrogen-doped porous lamellar carbon, and the specific surface area is matched with FeCl₃The additive proportion is increased, the micropore volume is increased, and the nitrogen content is increased along with FeCl₃The increase in the addition ratio increases first and then decreases.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.