A porous nitrogen-rich hard carbon material, a preparation method and application thereof

Abstract

The application belongs to the technical field of sodium ion battery negative electrode carbon material preparation, and discloses a porous nitrogen-rich hard carbon material and a preparation method and application thereof. The preparation method of the material is as follows: 1, 3, 5-trichlorobenzene is used as a carbon source, melamine is used as a nitrogen source, and diiron trioxide or reduced iron powder is used as a catalyst; the above raw materials are uniformly mixed, inert gas is introduced into a tube furnace for temperature carbonization to obtain a black solid powder product; after the obtained powder product is cooled, dilute hydrochloric acid is added to wash away inorganic metal salt and other impurities, and the porous nitrogen-rich hard carbon material is obtained after drying. The material is used in a sodium ion battery negative electrode and exhibits high energy density and excellent cycle stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sodium ion battery negative electrode carbon material preparation, and particularly relates to a porous nitrogen-rich hard carbon material and a preparation method and application thereof. BACKGROUND

[0002] Lithium ion batteries (LIBs) have been widely used in portable electronic devices, electric vehicles and energy storage systems due to their high energy density, high energy efficiency, long cycle life, reliability and stability. However, due to the limited reserves and uneven distribution of lithium resources, the price of lithium ion batteries is too high, which is not suitable for large-scale energy storage systems. Sodium ion batteries (SIBs) have attracted great interest of researchers due to their abundant sodium resources and comparable characteristics to lithium ion batteries, making them a strong competitor for large-scale energy storage. Therefore, developing low-cost and high-performance electrode materials is crucial for the commercialization of sodium ion batteries.

[0003] Heteroatom doping (N, B, S and P, etc.) and morphology design of carbon materials are common strategies to improve electrochemical performance. Among the many heteroatom-doped elements, N doping is most widely used in nanomaterials, which greatly improves ion migration and charge transfer processes. N doping often attempts to change the electronic structure of hard carbon by introducing a large number of defects, thereby obtaining better sodium ion storage capacity. SUMMARY

[0004] In order to overcome the shortcomings and deficiencies existing in the prior art, the primary purpose of the present application is to provide a preparation method of a porous nitrogen-rich hard carbon material.

[0005] Another purpose of the present application is to provide a porous nitrogen-rich hard carbon material prepared by the above preparation method, which has high energy density and excellent cycle stability.

[0006] Still another purpose of the present application is to provide the application of the above porous nitrogen-rich hard carbon material.

[0007] The purposes of the present application are achieved by the following technical solutions:

[0008] A preparation method of a porous nitrogen-rich hard carbon material, comprising the following operation steps:

[0009] (1) uniformly grinding and mixing 1, 3, 5-trichlorobenzene and melamine, then adding a catalyst and continuing to grind to make them uniformly mixed to obtain a powder mixture;

[0010] (2) Put the powder mixture obtained in step (1) into a tube furnace, pass inert gas, heat to 200℃ at a heating rate of 1-10℃ / min, keep for 1-3 hours, then heat to 600-800℃ at a heating rate of 1-10℃ / min, keep for 1-3 hours, and obtain black carbide after cooling;

[0011] (3) Pour the black carbide obtained in step (2) into a container, add deionized water and stir to form a uniform solution;

[0012] (4) Add hydrochloric acid solution to the uniform solution obtained in step (3), remove the catalyst and inorganic metal salt impurities under magnetic stirring at 500 r / min, and obtain a uniform solution after magnetic stirring for 6-12 hours;

[0013] (5) The uniform solution obtained in step (4) is repeatedly washed with deionized water and the black powder product is washed with anhydrous ethanol, filtered, and dried in a vacuum drying oven at 80℃ for 24 hours to obtain a porous nitrogen-rich hard carbon material.

[0014] The molar ratio of 1,3,5-trichlorobenzene to melamine in step (1) is 1:0.5-1:5.

[0015] The catalyst in step (1) is ferric oxide or reduced iron powder.

[0016] The inert gas in step (2) is nitrogen or argon.

[0017] A porous nitrogen-rich hard carbon material prepared by the above preparation method.

[0018] The above-mentioned porous nitrogen-rich hard carbon material is used in sodium ion battery negative electrode or supercapacitor.

[0019] The above-mentioned porous nitrogen-rich hard carbon material is used in the fields of energy, catalysis and environment.

[0020] A porous nitrogen-rich hard carbon material electrode sheet, comprising the above-mentioned porous nitrogen-rich hard carbon material.

[0021] The preparation method of the porous nitrogen-rich hard carbon material electrode sheet comprises the following steps:

[0022] The above-mentioned porous nitrogen-rich hard carbon material, conductive agent and adhesive are ball milled and uniformly mixed according to the mass ratio, N-methyl pyrrolidone is added to prepare an electrode slurry, a four-sided preparation device is used to uniformly coat it on a copper foil, and it is dried in an oven at 60℃ for 8-12 hours, and then cut into a circular battery electrode sheet with a diameter of 10mm;

[0023] The positive and negative electrode shells of the button cell, the sodium metal sheet, the spring, the gasket, the electrolyte, the separator, and the aforementioned porous nitrogen-rich hard carbon material electrode sheet are assembled into a sodium-ion half cell in a glove box filled with argon gas.

[0024] The principle of this invention is as follows:

[0025] This invention introduces nitrogen atoms into hard carbon materials by mixing carbon and nitrogen sources and carbonizing them at high temperatures, using ferric oxide or reduced iron powder as a catalyst to reduce the activation energy of the reaction and accelerate the reaction rate. Furthermore, it creates a large number of defects during the carbonization process, thereby improving the sodium ion storage capacity of hard carbon.

[0026] The present invention has the following advantages and beneficial effects compared with the prior art:

[0027] (1) The raw materials of this invention are readily available, inexpensive, and the synthesis method is simple.

[0028] (2) When the porous nitrogen-rich hard carbon material prepared by this invention is used as the negative electrode of sodium-ion battery, it is beneficial to increase the sodium ion insertion and extraction channels, and exhibits high initial discharge capacity, high energy density and excellent cycle stability. Attached Figure Description

[0029] Figure 1 The XRD energy spectrum of the porous nitrogen-rich hard carbon material prepared in Example 1 of this invention is shown.

[0030] Figure 2 Scanning electron microscope (SEM) image of the porous nitrogen-rich hard carbon material prepared in Example 1 of this invention.

[0031] Figure 3 This is a charge-discharge cycle curve of a sodium-ion battery assembled from the porous nitrogen-rich hard carbon material prepared in Example 1 at 0.1 A / g, where 1, 2 and 3 represent the first, second and third cycles, respectively.

[0032] Figure 4 This is a constant current cycle charge-discharge performance curve of a sodium-ion battery assembled from the porous nitrogen-rich hard carbon material prepared in Example 1, after 155 cycles at a current density of 0.1 A / g. Detailed Implementation

[0033] The following specific embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention.

[0034] Example 1

[0035] (1) Weigh 1.81g of 1,3,5-trichlorobenzene and 1.26g of melamine in a molar ratio of 1:1, grind and mix them evenly in an agate mortar, then weigh 0.8g of ferric oxide and add it to the mixture and continue grinding until it is evenly mixed to obtain a reddish-brown powder mixture.

[0036] (2) The red-brown powder mixture uniformly ground in step (1) was placed in a ceramic capsule and put in a tube furnace, inert gas (nitrogen) was introduced, and the temperature was raised to 200°C at a rate of 2°C / min, and kept for 2 hours, then raised to 600°C at a rate of 5°C / min, and kept for 2 hours. After cooling, a black carbide was obtained;

[0037] (3) The black carbide obtained in step (2) was poured into a beaker, 150 ml of deionized water and 50 ml of hydrochloric acid solution were added, and the mixture was stirred at 500 r / min to remove iron chloride and inorganic metal salts and other impurities. After stirring for 12 h, the mixture was washed with deionized water several times, and then dried in an oven at 80°C for 12 h to obtain a porous nitrogen-rich hard carbon material.

[0038] As Figure 1 The XRD pattern of the porous nitrogen-rich hard carbon material prepared in Example 1 shows that the sample has only carbon diffraction peaks, indicating that the impurities have been washed out, and the sample has good purity.

[0039] As Figure 2 is a scanning electron microscope image of the porous nitrogen-rich hard carbon material prepared in Example 1. As can be seen from the image, the surface morphology of the material presents a three-dimensional porous network structure.

[0040] The porous nitrogen-rich hard carbon material prepared in Example 1, conductive carbon black and PVDF were mixed and ground in a ball mill at a mass ratio of 8:1:1, and then mixed with N-methyl pyrrolidone to form a slurry. The slurry was then coated on a copper foil and dried in a vacuum oven at 60°C for 12 h, and then cut into a circular battery electrode piece with a diameter of 10 mm.

[0041] In an argon-filled glove box, a positive and negative electrode shell, a metal sodium sheet, a spring, a gasket, an electrolyte (1.0 M NaPF6 in DME), a separator (glass fiber), and the circular battery electrode piece containing the porous nitrogen-rich hard carbon material were assembled into a sodium ion button cell. The battery was tested using a LAND battery test system (CT2001A), and the charge and discharge voltage range was 0.01-3 V.

[0042] Figure 3 is a graph of the first three cycles of charge and discharge of the sodium ion button cell assembled with the porous nitrogen-rich hard carbon material prepared in Example 1 at a current density of 0.1 A / g. The initial charge capacity was 395.85 mAh g -1 , the discharge capacity was 473.78 mAh g -1 , and the charge and discharge efficiency was 83.55%, which showed a high initial discharge capacity.

[0043] Figure 4The constant current charge-discharge performance curve of the sodium ion button cell assembled by the porous nitrogen-rich hard carbon material prepared in Example 1 is shown in the figure, and it can be seen that the capacity retention rate is high, and the cycle stability is excellent.

[0044] Example 2

[0045] (1) 1.81 g of 1,3,5-trichlorobenzene and 2.52 g of melamine were weighed according to a molar ratio of 1:2, mixed and ground uniformly in a agate mortar, and then 0.8 g of ferric sesquioxide was weighed and added for further grinding to mix uniformly, to obtain a red-brown powder mixture;

[0046] (2) The red-brown powder mixture ground and mixed uniformly in step (1) was placed in a ceramic capsule and placed in a tube furnace, inert gas (nitrogen) was introduced, and the temperature was raised to 200°C at a rate of 2°C / min, and then held for 2 hours, and then the temperature was raised to 600°C at a rate of 5°C / min, and then held for 2 hours, and then cooled to obtain a black carbide;

[0047] (3) The black carbide obtained in step (2) was poured into a beaker and 150 ml of deionized water and 50 ml of hydrochloric acid solution were added, and the mixture was stirred at 500 r / min to remove iron chloride and inorganic metal salts and other impurities, and then stirred for 12 h, and then washed with deionized water and suction filtered, and then dried in a 80°C oven for 12 h, to obtain a porous nitrogen-rich hard carbon material.

[0048] The porous nitrogen-rich hard carbon material prepared in this example 2, conductive carbon black and PVDF were mixed and ground uniformly in a ball mill at a mass ratio of 8:1:1, N-methyl pyrrolidone was added and mixed uniformly to prepare a slurry, and then coated on a copper foil and dried in a 60°C vacuum oven for 12 h, and then cut into a circular battery pole piece with a diameter of 10 mm;

[0049] In an argon-filled glove box, a positive and negative electrode shell, a metal sodium sheet, a spring, a gasket, an electrolyte (1.0 M NaPF6 in DME), a separator (glass fiber) and the circular battery pole piece containing the porous nitrogen-rich hard carbon material were assembled into a button cell. The battery was tested using a LAND battery test system (CT2001A), and the charge-discharge voltage range was 0.01-3 V.

[0050] Example 3

[0051] (1) 1.81 g of 1,3,5-trichlorobenzene and 2.52 g of melamine were weighed according to a molar ratio of 1:2, mixed and ground uniformly in a agate mortar, and then 0.8 g of ferric sesquioxide was weighed and added for further grinding to mix uniformly, to obtain a red-brown powder mixture;

[0052] (2) The red-brown powder mixture uniformly ground in step (1) was placed in a ceramic canister and put in a tube furnace, inert gas (nitrogen) was introduced, and the temperature was raised to 200°C at a rate of 2°C / min, and kept for 2 hours, then raised to 700°C at a rate of 5°C / min, and kept for 2 hours, and after cooling, a black carbide was obtained;

[0053] (3) The black carbide obtained in step (2) was poured into a beaker, 150 ml of deionized water and 50 ml of hydrochloric acid solution were added, and the mixture was stirred at 500 r / min to remove iron chloride and inorganic metal salts and other impurities, and after stirring for 12 h, the mixture was washed with deionized water several times, and after drying, the mixture was placed in an 80°C oven for drying for 12 h, and a porous nitrogen-rich hard carbon material was obtained.

[0054] The porous nitrogen-rich hard carbon material prepared in Example 3, conductive carbon black and PVDF were mixed and ground in a ball mill at a mass ratio of 8:1:1, N-methyl pyrrolidone was added and mixed uniformly to prepare a slurry, and then the slurry was coated on a copper foil and dried in a vacuum oven at 60°C for 12 h, and the copper foil was cut into a circular battery pole piece with a diameter of 10 mm;

[0055] In an argon-filled glove box, a positive and negative electrode shell, a metal sodium sheet, a spring, a gasket, an electrolyte (1.0 M NaPF6 in DME), a separator (glass fiber) and the above-mentioned battery pole piece containing the porous nitrogen-rich hard carbon material were assembled into a button cell. The battery was tested using a LAND battery test system (CT2001A), and the charge and discharge voltage range was 0.01-3 V.

[0056] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. Use of a porous nitrogen-rich hard carbon material in a sodium-ion battery anode, characterized in that: The preparation method of the porous nitrogen-rich hard carbon material comprises the following operation steps: (1) uniformly grinding and mixing 1,3,5-trichlorobenzene and melamine, then adding a catalyst and continuing to grind to make them uniformly mixed to obtain a powder mixture; (2) placing the powder mixture obtained in step (1) in a tube furnace, passing in an inert gas, heating to 200 DEG C at a heating rate of 1-10 DEG C / min, keeping the temperature for 1-3 hours, then heating to 600-800 DEG C at a heating rate of 1-10 DEG C / min, keeping the temperature for 1-3 hours, and obtaining a black carbide after cooling; (3) pouring the black carbide obtained in step (2) into a container, adding deionized water and stirring to form a uniform solution; (4) adding a hydrochloric acid solution to the uniform solution obtained in step (3), removing the catalyst and inorganic metal salt impurities under magnetic stirring at 500 r / min, and obtaining a uniform solution after magnetic stirring for 6-12 hours; (5) repeatedly washing the uniform solution obtained in step (4) with deionized water, filtering by suction, then washing the black powder product with anhydrous ethanol, filtering, and drying in a vacuum drying box at 80 DEG C for 24 hours to obtain a porous nitrogen-rich hard carbon material.

2. The use of the porous nitrogen-rich hard carbon material according to claim 1 in the negative electrode of a sodium-ion battery, characterized in that: In step (1), the molar ratio of 1,3,5-trichlorobenzene to melamine is 1:0.5-1:

5.

3. The use of the porous nitrogen-rich hard carbon material according to claim 1 in the negative electrode of a sodium-ion battery, characterized in that: In step (1), the catalyst is diiron trioxide or reduced iron powder.

4. The use of the porous nitrogen-rich hard carbon material according to claim 1 in the negative electrode of a sodium-ion battery, characterized in that: In step (2), the inert gas is nitrogen or argon.

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