CN114335524A - A kind of heteroatom doped porous carbon nanobelt material and its preparation method and application - Google Patents

Abstract

The invention relates to the technical field of nano composite materials, in particular to a heteroatom-doped porous carbon nanobelt material and a preparation method and application thereof. The porous carbon nanobelt material is prepared by electrostatic spinning of a spinning solution obtained by selecting a water-soluble carbon precursor, an alkali metal oxysalt and water. Hetero atoms doped with the porous carbon nanobelt material are uniformly distributed in the carbon material and can be used as nucleation sites to facilitate uniform deposition of metal lithium on the surface and inhibit formation of dendritic crystals; the porous and nano-belt structure widens the insertion and extraction channels of lithium ions in the circulation process, and ensures the rapid transmission and deposition of the lithium ions; the continuous and stable three-dimensional conductive network structure is not only beneficial to the rapid transmission of electrons, but also can accommodate a large amount of metal lithium deposition and buffer the volume expansion. Therefore, when the heteroatom-doped porous carbon nanobelt material obtained by the invention is used as a lithium ion battery cathode material, excellent energy storage and quick charge performances are shown.

Description

A kind of heteroatom doped porous carbon nanobelt material and its preparation method and application

technical field

The invention relates to the technical field of nanocomposite materials, in particular to a heteroatom-doped porous carbon nanobelt material and a preparation method and application thereof.

Background technique

With the depletion of energy, environmental pollution and other issues have become increasingly prominent in the world, electric energy as a clean energy has been paid more and more attention. Lithium-ion batteries are the most widely used secondary batteries. They can be reversibly charged and discharged. They have the advantages of long cycle life, high operating voltage, high energy density, and easy transportation. They occupy an important position in the field of energy storage devices. At the same time, with the increasing development and popularization of the electric vehicle field, how to realize fast charging has also become a key research direction in the electric vehicle field. Replacing traditional energy sources is of great significance to achieving decarbonization.

However, there are still some defects in the electrode materials of lithium-ion batteries, which limit their further development in the field of fast charging. Different from graphite anode materials, porous carbon nanofibers with heteroatom doping can be used as excellent anode materials for fast charging of lithium ion batteries, which can realize fast storage of lithium ions and suppress the formation of metallic lithium dendrites. However, the existing porous carbon nanofiber materials often have problems such as poor structural continuity, limited heteroatom doping effect, and residual inactive metal precursors, which affect the specific surface area, heteroatom doping amount and electrical conductivity of porous carbon nanofiber materials. The improvement of the reversible capacity and the rate performance will affect the improvement of its reversible capacity and rate performance when it is used as a negative electrode material. In addition, the limited lithiophilic sites and unstable framework structure cannot effectively suppress the formation of lithium dendrites and buffer volume expansion, resulting in the risk of short circuit in the battery, which seriously affects the safety and stability of the battery.

SUMMARY OF THE INVENTION

Therefore, the technical problem to be solved by the present invention is to overcome the problems of reversible capacity and rate performance existing in the negative electrode material of lithium ion battery that cannot be effectively solved by the prior art, including: the problem of rapid transport of lithium ions and electrons in the negative electrode material, and the presence of metal lithium in the negative electrode material. The surface deposition of the electrode is not uniform, the dendrite is easy to form, and the volume expands irreversibly. The invention designs a three-dimensional porous nano-belt structure. By selecting water-soluble alkali metal oxo acid salts as auxiliary agents, the alkali metal ions can be directly dissolved in water to remove the alkali metal ions, so as to ensure that the obtained material has no inactive metal residues, which is beneficial for its use as a negative electrode. The material exhibits high reversible capacity, improves cycling stability and rate performance, and the obtained porous nanoribbon structure is doped with abundant heteroatoms. The doped heteroatoms are uniformly distributed in the carbon material and can be used as nucleation sites. It is beneficial to the uniform deposition of metallic lithium on the surface and inhibits the formation of dendrites; the porous and nanobelt structure widens the intercalation and deintercalation channels of lithium ions during cycling, ensuring the rapid transport and deposition of lithium ions; continuous and stable three-dimensional conductive network The structure not only facilitates the rapid transport of electrons, but also can accommodate a large amount of metallic lithium deposition, buffering the volume expansion. Therefore, when the heteroatom-doped porous carbon nanobelt material is used as a negative electrode material for lithium ion batteries, it exhibits excellent energy storage and fast charging performance.

For this reason, the present invention provides the following technical solutions:

The present invention provides a heteroatom-doped porous carbon nanobelt material. The porous carbon nanobelt material is doped with two or more kinds of heteroatoms, and the heteroatoms include nitrogen, oxygen, sulfur, phosphorus or chlorine. ;

The aspect ratio of the porous carbon nanobelt is 1000:1-8000:1, and the width is in the range of 0.05 μm to 10 μm.

Preferably, the atomic percentage of nitrogen is 0.2-10 at.%;

And/or, the atomic percentage of the oxygen is 5~25 at.%;

And/or, the atomic percentage of the sulfur is 0.1~10 at.%;

And/or, the atomic percentage of the phosphorus is 0.1~10 at.%;

And/or, the atomic percentage of the chlorine is 0.1-10 at.%.

Preferably, the thickness ranges from 1 nm to 100 nm.

Preferably, the pore size of the porous carbon nanobelt ranges from 0.5 nm to 50 nm;

And/or, the pore volume ranges from 0.1 cm ³ /g to 1.5 cm ³ /g;

And/or, the specific surface area is 600 m ² /g to 2000 m ² /g.

The present invention also provides a method for preparing a heteroatom-doped porous carbon nanobelt material, comprising the following steps: mixing a water-soluble carbon precursor, an alkali metal oxo acid salt, and water, and using the mixed solution as a spinning dope, Electrospinning is performed to obtain precursor fibers, and the obtained precursor fibers are subjected to post-treatment to prepare the porous carbon nanobelt material.

Preferably, the water-soluble carbon precursor includes: at least one of polyaspartic acid, serine, glycine, vitamin B1, folic acid, carboxymethyl cellulose, gelatin and betaine;

The alkali metal oxo salts include: at least one of potassium sulfate, sodium sulfate, lithium sulfate, potassium phosphate, sodium phosphate, potassium nitrate, sodium nitrite, potassium tetraborate, sodium tetraborate, lithium tetraborate and sodium hypochlorite .

Preferably, the mass ratio of the alkali metal oxo acid salt to the water-soluble carbon precursor is 1:1 to 1:10;

And/or, the mass ratio of the water-soluble carbon precursor to water is 1:1~1:20;

And/or, the concentration of alkali metal oxo-acid salt in the spinning dope is in the range of 0.0002 g/cm ³ to 1 g/cm ³ .

Preferably, the process conditions of the electrospinning include: spinning temperature of 40-80 °C, spinning time of 0.5-48 h, positive pressure of 5-18 kV, negative pressure of -8-1 kV, and receiving distance of 5-25 cm , the advancing speed is 0.02~0.16 mm/min.

Preferably, the post-treatment includes: pre-oxidizing, carbonizing, washing and drying the raw silk;

And/or, the pre-oxidation process includes: placing the raw silk sample in a tube furnace, passing air, from room temperature to 100-200°C at a heating rate of 1-10°C/min, and keeping the temperature for 0.5-2h. , and then use the heating rate of 0.2~5 °C/min to rise to 200~350 °C for 0.5~2 h;

And/or, the carbonization treatment process includes: taking out the pre-oxidized raw silk and placing it in a tube furnace, passing argon gas under closed conditions, and heating it to a temperature of 1-10°C/min in an inert gas atmosphere. 500~800 ℃, keep the temperature for 0.5~2 h and then cool down naturally;

And/or, the temperature of the drying treatment is 60-120°C.

The present invention also provides an application of the porous carbon nanobelt material or the porous carbon nanobelt material prepared by the above method in a negative electrode of a battery or an application in a fast-charging lithium ion battery.

The technical scheme of the present invention has the following advantages:

1. In the present invention, by selecting water-soluble alkali metal oxo acid salts as auxiliary agents, alkali metal ions can be directly dissolved in water to remove alkali metal ions to ensure that the obtained material has no inactive metal residues, which is beneficial to its high reversible capacity when it is used as a negative electrode material. Cycling stability and rate performance, the obtained three-dimensional porous nanoribbon material has good continuity, is doped with abundant heteroatoms, and the doped heteroatoms are uniformly distributed in the carbon material, which can be used as a nucleation site to facilitate metal The uniform deposition of lithium on the surface inhibits the formation of dendrites; the porous and nanobelt structure widens the intercalation and desorption channels of lithium ions during cycling, ensuring the rapid transport and deposition of lithium ions; the continuous and stable three-dimensional conductive network structure not only It is conducive to the rapid transport of electrons, and can accommodate a large amount of metal lithium deposition and buffer volume expansion. At the same time, since the heteroatoms are non-metallic heteroatoms, the specific surface area is increased, which is beneficial to the improvement of the lithium electrode capacity.

2. The porous carbon nanobelt material provided by the present invention selects alkali metal oxo acid salts as auxiliary agents and has multiple functions: alkali metal oxo acid salts are used as dopants to introduce heteroatoms such as sulfur, phosphorus, nitrogen or chlorine, and alkali metal oxo acid salts are used as dopants to introduce heteroatoms such as sulfur, phosphorus, nitrogen or chlorine. Oxy-acid salts are used as templates to introduce mesoporous structures and nanobelt structures, and alkali metal oxo-acid salts are used as activators to introduce microporous structures. The viscosity and rheological properties of the spinning solution are directly changed by the addition of alkali metal oxo-acid salts, and the nanobelt structure is directly formed in the process of spinning and drying instead of the traditional fiber structure.

3. The water-soluble carbon precursor selected for the porous carbon nanobelt material provided by the present invention contains heteroatoms such as nitrogen and oxygen, which can realize uniform in-situ doping of heteroatoms during the carbonization process, and the abundant heteroatoms can be used as additional lithium storage. sites, and act as uniform lithiophilic sites to inhibit the formation of possible metallic lithium dendrites.

4. In the preparation method of the porous carbon nanobelt material provided by the present invention, an alkali metal oxo-acid salt is used as an auxiliary agent to regulate and control the viscosity and rheological properties of the overall mixed solution, water is used as a solvent, and an environmentally friendly electrospinning is used. The silk process can obtain a three-dimensional nanobelt structure, and the operation is simple and effective. At the same time, the various atoms contained in the alkali metal oxo-acid salt itself can realize the in-situ doping of two or more heteroatoms, and at the same time, it can chemically react with biomass carbon. The reaction can form a hierarchical porous structure with coexistence of micropores and mesopores. It can achieve uniform pore formation on the surface and interior of carbon materials, introduce defects, and effectively increase the pore volume and specific surface area of the material. In the process of carbon formation, a variety of non-metallic heteroatoms can also be introduced to achieve in-situ heteroatom doping of the material.

5. In the present invention, the porous carbon nanobelt material is used as the negative electrode of lithium battery, which can continue the advantages of carbon-based materials. At the same time, the nanobelt structure can provide a transport channel for lithium ions to ensure rapid transport of lithium ions, and the doped heteroatoms are in the carbon material. Uniform distribution, as a nucleation site, it is conducive to the uniform deposition of metallic lithium on the surface and inhibits the formation of dendrites. The porous structure greatly increases the porosity and increases the intercalation and desorption channels of lithium ions during the cycle. The overall structural stability of the material has been significantly improved, and at the same time, the three-dimensional structure presented by the material can accommodate more metal lithium for rapid and uniform deposition as a framework, so as to achieve excellent energy storage and fast charging performance.

Description of drawings

In order to illustrate the specific embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

1 is a scanning electron microscope image of a heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention.

2 is a transmission electron microscope image of the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention.

FIG. 3 is a nitrogen adsorption and desorption curve diagram of the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention.

4 is a pore size distribution diagram of the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention.

FIG. 5 is an overall X-ray photoelectron spectrum diagram of the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention.

6 is a high-resolution spectrum of N element of the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention.

7 is a high-resolution spectrum of S element of the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention.

8 is a test chart of the capacity-voltage curve in a button-type half cell when the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention is used as a negative electrode material for a lithium ion battery.

9 is a test chart of rate performance in a button-type half cell when the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention is used as a negative electrode material for a lithium ion battery.

10 is a graph showing the long-cycle performance test in a button-type half-cell when the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention is used as a negative electrode material for a lithium ion battery.

11 is a comparison diagram of the coulombic efficiency performance of lithium deposition in a button-type half cell when the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention is used as a negative electrode material for a lithium ion battery.

12 is a graph of the charge-discharge performance of the lithium-to-lithium test in a button-type half cell when the heteroatom-doped porous carbon nanobelt material prepared in Example 1 of the present invention is used as a negative electrode material for a lithium ion battery.

Detailed ways

The following examples are provided for a better understanding of the present invention, and are not limited to the best embodiments, and do not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by combining with the features of other prior art shall fall within the protection scope of the present invention.

If the specific experimental steps or conditions are not indicated in the examples, it can be carried out according to the operations or conditions of the conventional experimental steps described in the literature in this field. The reagents or instruments used without the manufacturer's indication are all conventional reagent products that can be obtained from the market.

Example 1

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.588 g of polyaspartic acid, 0.570 g of sodium sulfate and 9.000 g of deionized water, respectively, mix them in a beaker, and stir them evenly on a stirring table at 60 °C until they are completely dissolved. , the spinning temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -4 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.08 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 150 °C at a heating rate of 3 °C/min, hold for 1 h, and then use a heating rate of 1 °C/min to rise to 270 °C for 1 h. Cool down to room temperature naturally, and then carbonize it: place it in a tube furnace, pass argon gas under closed conditions, heat up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, and cool down naturally after holding for 1 h. After being lowered to room temperature, it was taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

The scanning electron microscope image of the heteroatom-doped porous carbon nanobelt active material is shown in FIG. 1, and the transmission electron microscope image is shown in FIG. 2. It can be seen from FIGS. 1 and 2 that the heteroatom-doped porous carbon nanobelt obtained in the present application is obtained. The active material is a ribbon-like structure stacking morphology, its width is in the range of 0.2~1.5 μm, and the thickness is in the range of 1~10 nm; the nitrogen adsorption and desorption method is used for the heteroatom-doped porous carbon nanobelt active material. Figure 3 Nitrogen adsorption and desorption Figure 4 shows the pore size distribution diagram from the curve diagram and the pore size analysis. The specific surface area is 937 m ² /g, the pore volume is 0.56 cm ³ /g and the pore size is 1.5-8 nm. XPS was performed on the heteroatom-doped porous carbon nanobelt active material. Detection, the full spectrum of X-ray photoelectron spectrum and the high-resolution spectrum of the target element are obtained, as shown in Figures 5 to 7, the heteroatom-doped porous carbon nanobelt active material contains nitrogen, sulfur and oxygen atoms, wherein the atomic percentage of nitrogen is : 6.8 at.%, sulfur atomic percentage: 2.4 at.%, oxygen atomic percentage: 16.9 at.%.

Example 2

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.589 g of polyaspartic acid, 0.571 g of sodium phosphate and 9.002 g of deionized water, respectively, mix them in a beaker, and stir them evenly on a stirring table at 60 °C until they are completely dissolved. , the spinning temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -4 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.08 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 150 °C at a heating rate of 3 °C/min, hold for 1 h, and then use a heating rate of 1 °C/min to rise to 270 °C for 1 h. Cool down to room temperature naturally, and then carbonize it: place it in a tube furnace, pass argon gas under closed conditions, heat up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, and cool down naturally after holding for 1 h. After being lowered to room temperature, it was taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 3

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.587 g of betaine, 0.569 g of sodium sulfate and 9.001 g of deionized water, respectively, mix them in a beaker, stir evenly on a stirring table at 60°C until they are completely dissolved, and use them as spinning dope for electrospinning after dissolving. The temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -4 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.08 mm/min, and the spinning time was 6 h. The pre-oxidation of the silk was carried out by placing it in a tube furnace and ventilating the air from room temperature to 150 °C at a heating rate of 3 °C/min, holding for 1 h, then using a heating rate of 1 °C/min to increase to 270 °C for 1 h, and then cooling down to At room temperature, carbonize it again: put it in a tube furnace, pass argon gas under closed conditions, heat it up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, keep it for 1 h and then naturally cool down to room temperature After taking out, washing with water to remove non-carbon water-soluble ions, and drying in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 4

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.588 g of polyaspartic acid, 1.589 g of sodium sulfate and 9.002 g of deionized water, respectively, mix them in a beaker, and stir them evenly on a stirring table at 60 °C until they are completely dissolved. , the spinning temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -4 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.08 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 150 °C at a heating rate of 3 °C/min, hold for 1 h, and then use a heating rate of 1 °C/min to rise to 270 °C for 1 h. Cool down to room temperature naturally, and then carbonize it: place it in a tube furnace, pass argon gas under closed conditions, heat up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, and cool down naturally after holding for 1 h. After being lowered to room temperature, it was taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 5

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.586 g of polyaspartic acid, 0.571 g of sodium sulfate and 12.702 g of deionized water, respectively, mix them in a beaker, stir evenly on a stirring table at 60 °C until completely dissolved, and use them as spinning dope for electrospinning after dissolution. , the spinning temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -4 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.08 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 150 °C at a heating rate of 3 °C/min, hold for 1 h, and then use a heating rate of 1 °C/min to rise to 270 °C for 1 h. Cool down to room temperature naturally, and then carbonize it: place it in a tube furnace, pass argon gas under closed conditions, heat up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, and cool down naturally after holding for 1 h. After being lowered to room temperature, it was taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 6

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.586 g of polyaspartic acid, 0.569 g of sodium sulfate and 9.001 g of deionized water, respectively, mix them in a beaker, and stir them evenly on a stirring table at 60 °C until they are completely dissolved. , the spinning temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -4 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.08 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 150 °C at a heating rate of 3 °C/min, hold for 1 h, and then use a heating rate of 1 °C/min to rise to 300 °C for 1 h, Cool down to room temperature naturally, and then carbonize it: place it in a tube furnace, pass argon gas under closed conditions, heat up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, and cool down naturally after holding for 1 h. After being lowered to room temperature, it was taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 7

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.587 g of polyaspartic acid, 0.571 g of sodium sulfate and 9.001 g of deionized water, respectively, mix them in a beaker, stir evenly on a stirring table at 60 °C until they are completely dissolved, and use them as spinning dope for electrospinning after dissolution. , the spinning temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -4 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.08 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 150 °C at a heating rate of 3 °C/min, hold for 1 h, and then use a heating rate of 1 °C/min to rise to 270 °C for 1 h. Cool down to room temperature naturally, and then carbonize it: place it in a tube furnace, pass argon gas under closed conditions, heat up to 800 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, and cool down naturally after holding for 1 h. After being lowered to room temperature, it was taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 8

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.588 g of polyaspartic acid, 0.571 g of sodium sulfate and 9.001 g of deionized water, respectively, mix them in a beaker, and stir them evenly on a stirring table at 60 °C until they are completely dissolved. , the spinning temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -4 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.12 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 150 °C at a heating rate of 3 °C/min, hold for 1 h, and then use a heating rate of 1 °C/min to rise to 270 °C for 1 h. Cool down to room temperature naturally, and then carbonize it: place it in a tube furnace, pass argon gas under closed conditions, heat up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, and cool down naturally after holding for 1 h. After being lowered to room temperature, it was taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 9

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 0.571 g of polyaspartic acid, 0.570 g of sodium sulfate and 11.401 g of deionized water, respectively, mix them in a beaker, stir evenly on a stirring table at 60 °C until they are completely dissolved, and use them as spinning dope for electrospinning after dissolution. , the spinning temperature was set to 40 °C, the positive pressure was set to 18 kV, the negative pressure was set to -8 kV, the receiving distance was set to 5 cm, the advancing speed was set to 0.02 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 200 °C at a heating rate of 10 °C/min, hold for 2 h, and then use a heating rate of 0.2 °C/min to rise to 200 °C for 0.5 h. , naturally cooled to room temperature, and then carbonized: put it in a tube furnace, pass argon gas under closed conditions, raise the temperature to 500 °C at a heating rate of 1 °C/min in an inert gas atmosphere, and cool down naturally after holding for 2 h. , taken out after being lowered to room temperature, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 120° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 10

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 5.701 g of polyaspartic acid, 0.570 g of sodium sulfate and 5.702 g of deionized water, respectively, mix them in a beaker, and stir them evenly on a stirring table at 60 °C until they are completely dissolved. , the spinning temperature was set to 80 °C, the positive pressure was set to 5 kV, the negative pressure was set to -1 kV, the receiving distance was set to 25 cm, the advancing speed was set to 0.16 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 100 °C at a heating rate of 1 °C/min, hold for 0.5 h, and then use a heating rate of 5 °C/min to rise to 350 °C for 2 h. , naturally cooled to room temperature, and then carbonized: placed in a tube furnace, passed argon gas under closed conditions, heated to 800 °C at a heating rate of 10 °C/min in an inert gas atmosphere, and kept for 0.5 h. The temperature was lowered to room temperature, then taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 60° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Example 11

A kind of porous carbon nanobelt material, its preparation method is:

Weigh 1.588 g of polyaspartic acid, 0.571 g of sodium hypochlorite, and 9.001 g of deionized water, respectively, mix them in a beaker, stir evenly on a stirring table at 60 °C until completely dissolved, set the spinning temperature to 60 °C, and set a positive pressure. Set to 10 kV, negative pressure to -4 kV, receiving distance to 15 cm, advancing speed to 0.08 mm/min, spinning time to 6 h, to obtain raw silk, pre-oxidize the raw silk: place it in a tubular The air in the furnace was raised from room temperature to 150 °C at a heating rate of 3 °C/min, kept for 1 h, then raised to 270 °C with a heating rate of 1 °C/min for 1 h, and cooled to room temperature naturally, and then carbonized: In a tube furnace, pass argon gas under closed conditions, heat up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, cool down naturally after holding for 1 h, take it out after cooling to room temperature, wash with water to remove non-carbon water-soluble ions , and dried in an oven at 80° C. to obtain the heteroatom-doped porous carbon nanobelt active material.

Comparative Example 1

A heteroatom-doped carbon nanofiber material, the preparation method of which is:

Weigh 1.588 g of polyaspartic acid, 0.020 g of sodium sulfate, and 9.000 g of deionized water, respectively, mix them in a beaker, stir them evenly on a stirring table at 60 °C until they are completely dissolved, and use them as spinning dope for electrospinning. , the spinning temperature was set to 60 °C, the positive pressure was set to 10 kV, the negative pressure was set to -14 kV, the receiving distance was set to 15 cm, the advancing speed was set to 0.12 mm/min, and the spinning time was set to 6 h to obtain the raw silk. , pre-oxidize the raw silk: put it in a tube furnace and let the air rise from room temperature to 150 °C at a heating rate of 3 °C/min, hold for 1 h, and then use a heating rate of 1 °C/min to rise to 270 °C for 1 h. Cool down to room temperature naturally, and then carbonize it: place it in a tube furnace, pass argon gas under closed conditions, heat up to 700 °C at a heating rate of 2.5 °C/min in an inert gas atmosphere, and cool down naturally after holding for 1 h. After cooling to room temperature, it was taken out, washed with water to remove non-carbon water-soluble ions, and dried in an oven at 80 °C to obtain heteroatom-doped carbon nanofiber materials with fiber diameters ranging from 0.5 to 30 μm.

Comparative Example 2

A cobalt and nitrogen-doped porous carbon composite nanofiber, the preparation method of which is:

1) Preparation of spinning solution: Chitosan with an average molecular weight of 600,000 is dissolved in an aqueous solution of acetic acid, polyethylene oxide with an average molecular weight of 1 million is dissolved in deionized water, and polyethyleneimine is diluted with deionized water and added. Cobalt acetate tetrahydrate, the above three solutions were mixed and stirred evenly, and TritonX-100 was added to obtain a spinning solution, wherein the concentration of chitosan was 2.9wt%, the concentration of acetic acid was 1.1wt%, and the concentration of polyethylene oxide was 2.4wt%, the concentration of polyethyleneimine is 0.5wt%, the concentration of cobalt acetate is 0.2wt%, and the concentration of TritonX-100 is 0.8wt%; the mixed solution is stirred in a 30 ℃ water bath for 8h.

2) Electrospinning: The obtained spinning solution was put into a syringe for electrospinning, wherein the spinning distance was 10 cm, the solution flow rate was 0.3 mL/h, and the applied voltage was 15 kV.

3) Heat treatment: The mixed polymer fibers obtained by spinning are placed in a tube furnace, pre-oxidized at 150 °C for 4 hours in the air, and then heated to 240 °C at 3 °C/min in an inert atmosphere, maintained at a constant temperature for 2 hours, and then heated at 3 °C for 3 hours. The temperature was raised to 340°C/min for 2h, then 3°C/min was raised to 800°C, and the temperature was kept constant for 2h. Finally, cobalt and nitrogen-doped porous carbon composite nanofibers were obtained, and the fiber diameter ranged from 0.05 to 0.08 μm.

Experimental example 1:

The porous carbon nanobelts prepared in Examples 1 to 11 and the nanofibers of Comparative Examples 1 to 2 were characterized by SEM and TEM. The experimental results are shown in Table 1:

Table 1 SEM and TEM characterization test results of porous carbon nanoribbons

The experimental results show that the morphology of the porous carbon nanobelt materials obtained in Examples 1 to 11 of the present invention presents a stacking of band-like structures, the width ranges from 0.09 μm to 6.7 μm, the thickness ranges from 1 nm to 64 nm, and the surface and interior are uniformly distributed. Porous structure.

Experimental example 2:

The porous carbon nanobelts prepared in Examples 1 to 11 and the nanofibers of Comparative Examples 1 to 2 were subjected to a BET test, and the experimental results were shown in Table 2:

Table 2 BET test results

Experimental Example 3: The porous carbon nanobelts prepared in Examples 1 to 11 and the nanofibers of Comparative Examples 1 to 2 were subjected to XPS spectrum analysis to obtain the atomic percentage of heteroatoms. The experimental results are shown in Table 3.

Table 3 XPS spectrum analysis results

Experimental example 4:

The porous carbon nanobelt active materials prepared in Examples 1-11 and the nanofiber materials obtained in Comparative Examples 1-2 were mixed with a binder in a mass ratio of 20:1, wherein the binder was PVDF (polyvinylidene fluoride). Ethylene), used water as solvent, ground with mortar until uniform, coated on copper foil with a diameter of 14 mm, dried in a vacuum oven at 60 °C for 12 h, taken out and used as the negative electrode, and the lithium sheet as the counter electrode , assembled into a button-type lithium-ion half-cell;

Using commercial graphite as the negative electrode and lithium sheet as the counter electrode, a button-type lithium-ion half-cell was assembled. As a comparative example 3, the commercial graphite negative electrode was purchased from Xianfeng Nano Technology Co., Ltd. with a purity of 99.0 wt%, and the lithium sheet was purchased from Tianjin Zhongshan Neng Lithium Industry Co., Ltd., diameter 15.6 mm;

Among them, the model of the button-type lithium-ion half battery is CR2032.

The porous carbon nanobelt active material obtained in Example 1 was used as a negative electrode material for a lithium ion battery, and a button-type lithium ion half battery was assembled to conduct a capacity and voltage test. The test chart is shown in Figure 8. The nanobelt active material is used as the negative electrode material of lithium ion battery, and the rate performance test is carried out. The test chart is shown in Figure 9. The porous carbon nanobelt active material obtained in Example 1 is used as the negative electrode material of lithium ion battery. Cycle performance test, the test results are shown in Figure 10. The specific results are shown in Table 1.

The obtained button-type lithium-ion half-cell was tested for rate and long cycle, the voltage window was selected as 0.01~3 V, and the current density of rate test was selected as follows: 0.2C, 0.5C, 1C, 2C, 5C, 10C, 20C, The long-cycle test current density is 6C, and the test results are shown in Table 4.

Table 4 Button-type lithium-ion half-cell rate and long-cycle test results

It can be seen that when the porous carbon nanobelt active materials prepared in Examples 1~11 are used as the negative electrode, the specific capacity of the battery is 576~620 mAh g ^-1 under the current density of 0.2 C, and when it increases to 20 C, the specific capacity of the battery is 576~620 mAh g -1 . There are still 200~240 mAh g ^-1 , showing good rate capability. In the long-cycle test after activation for 400 cycles, the specific capacity can reach 507~570 mAh g ^-1 , and the standard capacity of commercial graphite anode is 372 mAh g ^-1 , which is 1.5 times the standard capacity of commercial graphite anode, and the performance is excellent.

Experimental example 5:

The button-type half-cell obtained by using the pure metal lithium deposited on the surface as the negative electrode is used as Comparative Example 4, and the porous carbon nanobelt active materials prepared in Examples 1-11 and the nanofiber materials obtained in Comparative Examples 1-2 are used as lithium-ion batteries. The button-type half-cell obtained from the negative electrode material and the button-type half-cell obtained in Comparative Example 4 were subjected to lithium deposition and stripping tests. First, 3 mAh cm ^-2 of lithium was pre-deposited under the condition of 1 mAcm ^-2 , and then 1 mA cm ^-2 , 1 Lithium was deposited and stripped under the condition of mAh cm ^-2 , the cut-off voltage was set to 1 V, and the ratio of the discharge capacity to the charge capacity was calculated to obtain the Coulomb efficiency;

When the heteroatom-doped porous carbon nanobelt material prepared in Example 1 is used as a negative electrode material for a lithium ion battery, the lithium deposition Coulomb efficiency performance and the lithium-to-lithium test charge-discharge performance are tested in a button-type half-cell. The test diagram is shown in Figure 11. ~ Figure 12 and results are shown in Table 5.

Table 5 Lithium deposition stripping test results

From the above results, it can be clearly seen that the Coulombic efficiency under the conditions of 1 mA cm ^-2 and 1 mAh cm ^-2 is significantly better than that of the battery with the pure metal lithium deposited on the surface as the negative electrode, and the battery can still maintain 93.9~ after 130 cycles. The Coulomb efficiency of 96.6% shows that the material assembled into a symmetrical battery can maintain a stable voltage after 500 h of cycling, and has good long-cycle performance.

Compared with the currently reported negative electrode materials, the materials prepared by this method exhibit better energy storage and fast charging performance.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. And the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (10)

1. a heteroatom-doped porous carbon nanobelt material is characterized in that, the porous carbon nanobelt material is doped with two or more heteroatoms, and the heteroatoms include: nitrogen, oxygen, sulfur, phosphorus or chlorine; The aspect ratio of the porous carbon nanobelt is 1000:1-8000:1, and the width is in the range of 0.05 μm-10 μm. 2. The heteroatom-doped porous carbon nanobelt material of claim 1, wherein the nitrogen atomic percentage is 0.2 to 10 at.%; And/or, the atomic percentage of the oxygen is 5~25 at.%; And/or, the atomic percentage of the sulfur is 0.1~10 at.%; And/or, the atomic percentage of the phosphorus is 0.1~10 at.%; And/or, the atomic percentage of the chlorine is 0.1-10 at.%. 3 . The heteroatom-doped porous carbon nanobelt material according to claim 1 , wherein the thickness of the porous carbon nanobelt ranges from 1 nm to 100 nm. 4 . 4. The heteroatom-doped porous carbon nanobelt material according to claim 1, wherein the pore diameter of the porous carbon nanobelt ranges from 0.5 nm to 50 nm; And/or, the pore volume ranges from 0.1 cm ³ /g to 1.5 cm ³ /g; And/or, the specific surface area is 600 m ² /g to 2000 m ² /g. 5. The preparation method of the heteroatom-doped porous carbon nanobelt material according to any one of claims 1 to 4, characterized in that, comprising the steps of: mixing water-soluble carbon precursor, alkali metal oxo acid salt, Mixing with water, using the mixed solution as a spinning stock solution, performing electrospinning to obtain a precursor, and subjecting the obtained precursor to post-treatment to prepare the porous carbon nanobelt material. 6. The method for preparing a heteroatom-doped porous carbon nanobelt material according to claim 5, wherein the water-soluble carbon precursor comprises: polyaspartic acid, serine, glycine, vitamin B1, folic acid , at least one of carboxymethyl cellulose, gelatin and betaine; And/or, the alkali metal oxo salts include: potassium sulfate, sodium sulfate, lithium sulfate, potassium phosphate, sodium phosphate, potassium nitrate, sodium nitrite, potassium tetraborate, sodium tetraborate, lithium tetraborate and sodium hypochlorite at least one of. 7. the preparation method of the porous carbon nanobelt material of heteroatom doping as described in any one of claim 5～6, is characterized in that, the mass ratio of alkali metal oxo acid salt and water-soluble carbon precursor is 1: 1~1:10; And/or, the mass ratio of the water-soluble carbon precursor to water is 1:1~1:20; And/or, the concentration of alkali metal oxo-acid salt in the spinning dope is in the range of 0.0002 g/cm ³ to 1 g/cm ³ . 8. The preparation method of a heteroatom-doped porous carbon nanobelt material according to claim 5, wherein the process conditions of the electrospinning comprise: a spinning temperature of 40-80 °C, a spinning time of 0.5- 48h, positive pressure 5~18kV, negative pressure -8~-1kV, receiving distance 5~25 cm, advancing speed 0.02~0.16 mm/min. 9 . The method for preparing a heteroatom-doped porous carbon nanobelt material according to claim 5 , wherein the post-treatment comprises: pre-oxidizing, carbonizing, washing, and drying the raw silk; 10 . And/or, the pre-oxidation process includes: in an air atmosphere, the raw silk is kept at 100-200°C for 0.5-2h, and then heated to 200-350°C for 0.5-2h; And/or, the carbonization treatment process includes: keeping the pre-oxidized raw silk at 500-800° C. for 0.5-2 hours in an inert gas atmosphere; And/or, the temperature of the drying treatment is 60-120°C. 10. The application of the porous carbon nanobelt material according to any one of claims 1 to 4 in a negative electrode of a battery or an application in a fast-charging lithium-ion battery.

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