Preparation method of nitrogen-doped carbon black and battery thereof

Abstract

The application discloses a preparation method of nitrogen-doped carbon black, comprising the following steps: a mixing step, in which a carbon source is mixed with a nitrogen-doping modifier to obtain a mixture; and a heating step, in which the mixture is carbonized and doped with nitrogen under heating conditions to obtain the nitrogen-doped carbon black.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a method for preparing nitrogen-doped carbon black and a battery thereof. Background Technology

[0002] Currently, carbon black can be divided into rubber-grade carbon black and non-rubber-grade carbon black. Conductive carbon black, a type of non-rubber-grade carbon black, possesses the characteristics of "three highs and one excellent"—high specific surface area, high structure, high purity, and excellent conductivity. With the rapid development of the new energy industry, lithium batteries have become the primary application scenario for conductive carbon black. Lithium-ion batteries require conductive agents to have excellent conductivity, low density, and stable structure and chemical properties. Conductive carbon black not only meets the requirements that the conductive agent does not participate in redox reactions in the battery and has high resistance to acid and alkali corrosion, but also features low cost and light weight.

[0003] The mainstream conductive carbon black products for lithium batteries currently have low specific surface areas. Although low specific surface areas have excellent dispersibility, their conductivity is difficult to improve further. Moreover, the amount of low-end conductive carbon black added is much larger than that of high-end conductive carbon black, generally 3-4 times that of high-end conductive carbon black. At present, the application scope of low-end conductive carbon black used in rubber and plastic products such as mining pipes and cable shielding is limited, and it cannot be used in large quantities in the preparation of lithium batteries. Summary of the Invention

[0004] The present invention aims to provide a method for efficiently preparing a more valuable nitrogen-doped carbon black by using bamboo as a carbon source and urea as a nitrogen doping modifier.

[0005] According to a first aspect, one embodiment provides a method for preparing nitrogen-doped carbon black, comprising: The mixing step includes mixing a carbon source with a nitrogen-doped modifier to obtain a mixture; The heating step includes carbonizing the mixture under heating conditions and then performing nitrogen doping to obtain the nitrogen-doped carbon black.

[0006] In one embodiment, the nitrogen-doped modifier includes, but is not limited to, urea.

[0007] This invention provides, for the first time, a method for preparing nitrogen-doped carbon black using bamboo as a carbon source. The inventors made significant discoveries through extensive experimentation, obtaining nitrogen-doped carbon black by mixing bamboo powder and urea powder, followed by high-temperature carbonization and nitrogen doping modification. When used as a conductive agent in lithium-ion batteries, this nitrogen-doped carbon black exhibits high specific capacity and cycle stability. Specific experimental studies show that nitrogen-doped carbon black, when used as a conductive agent in lithium-ion batteries, possesses high specific capacity; after 1000 cycles, no significant capacity decay was observed, demonstrating excellent cycle performance.

[0008] Furthermore, the inventors emphasize that each reaction step in this invention is crucial and indispensable. The nitrogen-doped carbon black prepared without any one of these steps will not exhibit excellent cycle performance when used as a conductive agent in lithium-ion batteries. The nitrogen-doped carbon black prepared by mixing bamboo powder and urea powder using bamboo powder as the carbon source, followed by two steps of high-temperature carbonization and nitrogen doping modification, possesses excellent cycle performance when used as a conductive agent in lithium-ion batteries.

[0009] In one embodiment, the mixture in the mixing step is in powder form. The method for preparing the powder is not limited; for example, a carbon source and urea can be mixed and then pulverized using mechanical equipment to obtain a powdered mixture, or the carbon source and urea can be pulverized separately beforehand and then mixed to obtain a powdered mixture.

[0010] In one embodiment, the carbon source includes bamboo.

[0011] In one embodiment, the bamboo in the mixing step includes, but is not limited to, at least one of arrow bamboo, moso bamboo, purple bamboo, palm bamboo, bitter bamboo, and rigid bamboo.

[0012] In one embodiment, the carbon source includes the above-ground stem of bamboo.

[0013] In one embodiment, the pulverization method includes, but is not limited to, air jet milling and mechanical milling.

[0014] In one embodiment, the method of mixing bamboo and urea includes, but is not limited to, ball milling, stirring, and oscillation mixing.

[0015] In one embodiment, during the mixing step, the particle size of the mixture is 200-300 mesh. The desired particle size can be obtained by sieving with a mesh screen.

[0016] In one embodiment, the bamboo is in powder form during the mixing step.

[0017] In one embodiment, the nitrogen-doped modifier is in powder form during the mixing step.

[0018] In one embodiment, the bamboo particles in the mixing step are 200-300 mesh.

[0019] In one embodiment, during the mixing step, the particle size of the nitrogen-doped modifier is 200-300 mesh.

[0020] In one embodiment, during the mixing step, the nitrogen-doped modifier: bamboo = (5-10): (2-3) by mass.

[0021] In one embodiment, during the mixing step, the nitrogen-doped modifier: bamboo = (10-20) g : (4-6) g by mass.

[0022] In one embodiment, during the heating step, the mixture is heated to 1000-1500 °C.

[0023] In one embodiment, during the heating step, the heating rate of the mixture is 2-10 °C / min.

[0024] In one embodiment, during the heating step, the mixture is heated in a nitrogen atmosphere.

[0025] According to the second aspect, one embodiment provides nitrogen-doped carbon black prepared by the preparation method described in the first aspect.

[0026] According to a third aspect, one embodiment provides a conductive agent containing the nitrogen-doped carbon black described in the second aspect.

[0027] According to the fourth aspect, one embodiment provides a battery containing nitrogen-doped carbon black as described in the second aspect, or a conductive agent as described in the third aspect.

[0028] In one embodiment, the battery includes, but is not limited to, lithium-ion batteries and sodium-ion batteries.

[0029] In one embodiment, the present invention provides a novel method for preparing nitrogen-doped carbon black using bamboo as a carbon source. The present invention prepares nitrogen-doped carbon black by mixing bamboo powder and urea powder, followed by two steps: high-temperature carbonization and nitrogen doping modification. When used as a conductive agent in lithium-ion batteries, this nitrogen-doped carbon black exhibits high specific capacity and cycle stability.

[0030] In one embodiment, the method provided by the present invention is safe and environmentally friendly, easy to operate, low in preparation cost, and easy to industrialize.

[0031] In one embodiment, the inventors discovered that the selection of the nitrogen-doping modifier plays a crucial role in determining the excellent cycle performance of the nitrogen-doped carbon black when used as a conductive agent in lithium-ion batteries, during the preparation of nitrogen-doped carbon black using the method provided by this invention. The inventors were surprised to find that when urea was used as the nitrogen-doping modifier, the prepared nitrogen-doped carbon black exhibited excellent cycle performance when used as a conductive agent in lithium-ion batteries; its cycle performance was far superior to that of carbon black prepared without urea.

[0032] In one embodiment, the present invention provides a novel method for preparing nitrogen-doped carbon black using bamboo as a carbon source. The nitrogen-doped carbon black prepared by mixing bamboo powder and urea powder, followed by high-temperature carbonization and nitrogen doping modification, exhibits high specific capacity and cycle stability when used as a conductive agent in lithium-ion batteries. Attached Figure Description

[0033] Figure 1 This is an appearance diagram of the nitrogen-doped carbon black powder prepared in Example 1 of the present invention.

[0034] Figure 2 This is a transmission electron microscope image of the nitrogen-doped carbon black powder prepared in Example 1 of the present invention. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other materials or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0036] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0037] The serial numbers assigned to components in this article, such as "first" and "second", are used only to distinguish the objects being described and have no sequential or technical meaning.

[0038] Example 1 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1200 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0039] Figure 1 This is an appearance diagram of the nitrogen-doped carbon black powder prepared in this embodiment.

[0040] Figure 2 This is a transmission electron microscope image of the nitrogen-doped carbon black powder prepared in this embodiment.

[0041] Example 2 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1000 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0042] The difference between Example 2 and Example 1 is that the high-temperature carbonization and nitrogen doping modification temperature in Example 2 is 1000℃, while the high-temperature carbonization and nitrogen doping modification temperature in Example 1 is 1200℃.

[0043] Example 3 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1100 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0044] The difference between Example 3 and Example 1 is that the high-temperature carbonization and nitrogen doping modification temperature of Example 3 is 1100℃, while the high-temperature carbonization and nitrogen doping modification temperature of Example 1 is 1200℃.

[0045] Example 4 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1300 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0046] The difference between Example 4 and Example 1 is that the high-temperature carbonization and nitrogen doping modification temperature of Example 4 is 1300℃, while the high-temperature carbonization and nitrogen doping modification temperature of Example 1 is 1200℃.

[0047] Example 5 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1400 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0048] The difference between Example 5 and Example 1 is that the high-temperature carbonization and nitrogen doping modification temperature of Example 5 is 1400℃, while the high-temperature carbonization and nitrogen doping modification temperature of Example 1 is 1200℃.

[0049] Example 6 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1500 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0050] The difference between Example 6 and Example 1 is that the high-temperature carbonization and nitrogen doping modification temperature of Example 6 is 1500℃, while the high-temperature carbonization and nitrogen doping modification temperature of Example 1 is 1200℃.

[0051] Example 7 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1200 °C at a heating rate of 3 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0052] The difference between Example 7 and Example 1 is that the heating rate in Example 7 is 3 °C / min, while the heating rate in Example 1 is 5 °C / min.

[0053] Example 8 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1200 °C at a heating rate of 7 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0054] The difference between Example 8 and Example 1 is that the heating rate in Example 8 is 7 °C / min, while the heating rate in Example 1 is 5 °C / min.

[0055] Example 9 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of urea powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1200 °C at a heating rate of 9 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0056] The difference between Example 9 and Example 1 is that the heating rate in Example 9 is 9 °C / min, while the heating rate in Example 1 is 5 °C / min.

[0057] Comparative Example 1 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 5 g of bamboo powder was added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1200 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0058] The difference between Comparative Example 1 and Example 1 is that urea powder was not used as a nitrogen doping modifier in Comparative Example 1, while urea powder was used as a nitrogen doping modifier in Example 1.

[0059] Comparative Example 2 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of ammonium carbonate powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1200 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0060] The difference between Comparative Example 2 and Example 1 is that ammonium carbonate powder was used as the nitrogen doping modifier in Comparative Example 2, while urea powder was used as the nitrogen doping modifier in Example 1.

[0061] Comparative Example 3 First, bamboo and urea were pulverized using a pulverizer, and then passed through a 200-mesh sieve to obtain bamboo powder and urea powder. 15 g of ammonium nitrate powder and 5 g of bamboo powder were added to a ball mill jar and ball-milled for 1 hour. The milled material was then added to a graphite crucible and heated to 1200 °C at a heating rate of 5 °C / min under a nitrogen atmosphere for 5 hours for high-temperature carbonization and nitrogen doping modification to obtain nitrogen-doped carbon black.

[0062] The difference between Comparative Example 3 and Example 1 is that ammonium nitrate powder was used as the nitrogen doping modifier in Comparative Example 3, while urea powder was used as the nitrogen doping modifier in Example 1.

[0063] Bio-based carbon black prepared in Examples 1-9 and Comparative Examples 1-3 were used as conductive agents for lithium-ion batteries, lithium iron phosphate (brand: Kejing; product number: P198-DF5) was used as the positive electrode material, and PVDF (brand: Arkema; ​​product model: MA-EN-BI-01) was used as the binder to prepare electrodes, and button cells were assembled. The discharge specific capacity (mAh / g) of the button half-cell after 1000 cycles at a current density of 100 mA / g, as well as the initial coulombic efficiency (%) and initial discharge specific capacity (mAh / g) of the button half-cell at a current density of 100 mA / g, were tested. The test results are shown in Table 1.

[0064] LiFePO4, carbon black, and PVDF were mixed in a mass ratio of 94:3:3 and stirred into a slurry using N-methylpyrrolidone (brand: KELUD; product model: MA-EN-OT-01) as a solvent. The slurry was then coated onto aluminum foil (brand: KELUD; product model: MA-EN-CU-0N) and thoroughly dried to form the positive electrode. A lithium metal sheet was used as the negative electrode, a Celgard 2500 polypropylene porous membrane (brand: KELUD; product model: MA-EN-SE-07) as the separator, and 1.0 M LiPF6 / EC-DMC-EMC=1:1:1 Vol% with 1.0% VC (brand: Duoduo Chemical Reagent Network; product model: LB-092) as the electrolyte. The battery was assembled in an argon-protected glove box. After 24 hours of resting, the battery cycle performance was tested using a battery testing system from Wuhan Landian Electronics Co., Ltd.

[0065] Table 1

[0066] As shown in Table 1, when the nitrogen-doped carbon black prepared in Example 1 is used as a conductive agent in lithium-ion batteries, the initial coulombic efficiency is 99% at a current density of 100 mA / g, the initial discharge specific capacity is above 169 mAh / g, and the discharge specific capacity after 1000 cycles is 161 mAh / g. This indicates that the nitrogen-doped carbon black prepared using bamboo as a carbon source according to the method described in this invention exhibits excellent cycle performance and high specific capacity as a conductive agent in lithium-ion batteries.

[0067] When the nitrogen-doped carbon black prepared in Examples 1 and 2-6 is used as a conductive agent in lithium-ion batteries, the analysis revealed that the high-temperature carbonization and nitrogen doping modification temperature has a significant impact on the performance of the nitrogen-doped carbon black. The initial coulombic efficiency, initial discharge specific capacity, and discharge specific capacity after 1000 cycles of the nitrogen-doped carbon black in Examples 2-6 are much lower than those of the nitrogen-doped carbon black in Example 1. This indicates that in the process of preparing nitrogen-doped carbon black using the method described in this invention, the selection of the high-temperature carbonization and nitrogen doping modification temperature plays a crucial role in whether the prepared nitrogen-doped carbon black has excellent cycle performance when used as a conductive agent in lithium-ion batteries. When the high-temperature carbonization and nitrogen doping modification temperature is selected as 1200 ℃, the prepared nitrogen-doped carbon black has excellent cycle performance, high initial coulombic efficiency, and high initial discharge specific capacity when used as a conductive agent in lithium-ion batteries. The main reason is that when the high-temperature carbonization and nitrogen doping modification temperature is below 1200 ℃, the carbonization and nitrogen doping of the synthesized material are insufficient, while when the high-temperature carbonization and nitrogen doping modification temperature is above 1200 ℃, the synthesized material undergoes structural collapse.

[0068] When the nitrogen-doped carbon black prepared in Examples 1 and 7-9 is used as a conductive agent in lithium-ion batteries, the analysis revealed that the heating rate has a significant impact on the performance of the nitrogen-doped carbon black. The initial coulombic efficiency, initial discharge specific capacity, and discharge specific capacity after 1000 cycles of the nitrogen-doped carbon black in Examples 7-9 are much smaller than those of the nitrogen-doped carbon black in Example 1. This indicates that in the process of preparing nitrogen-doped carbon black using the method provided by this invention, both excessively slow and excessively fast heating rates are not conducive to constructing a perfect nitrogen-doped carbon black structure. A heating rate of 5 ℃ / min is beneficial for nitrogen-doped carbon black to obtain excellent lithium storage performance.

[0069] Studies in Example 1 and Comparative Example 1 revealed that the nitrogen-doped carbon black prepared using urea powder as a nitrogen doping modifier exhibited significantly better initial coulombic efficiency, initial discharge specific capacity, and discharge specific capacity after 1000 cycles compared to carbon black prepared without urea powder as a nitrogen doping modifier. Studies in Example 1 and Comparative Examples 2-3 further showed that the nitrogen-doped carbon black prepared using urea powder as a nitrogen doping modifier had significantly better initial coulombic efficiency, initial discharge specific capacity, and discharge specific capacity after 1000 cycles compared to nitrogen-doped carbon black prepared using ammonium carbonate powder or ammonium nitrate powder as nitrogen doping modifiers. This indicates that the nitrogen doping modifier has a significant impact on the performance of the prepared nitrogen-doped carbon black; the addition of a nitrogen doping modifier is beneficial for improving the structure of the nitrogen-doped carbon black, and a more optimized structure facilitates the insertion and extraction of lithium ions.

[0070] The data from this invention show that nitrogen-doped carbon black prepared from bamboo has high initial coulombic efficiency, high specific capacity, and excellent cycle stability when used as a conductive agent in lithium-ion batteries. In addition, the method provided by this invention is safe and environmentally friendly, easy to operate, low in preparation cost, and easy to industrialize.

[0071] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A method for preparing nitrogen-doped carbon black, characterized in that, include: The mixing step includes mixing a carbon source with a nitrogen-doped modifier to obtain a mixture; wherein the carbon source includes powdered bamboo and the nitrogen-doped modifier includes powdered urea. The heating step includes carbonizing the mixture under heating conditions and performing nitrogen doping to obtain the nitrogen-doped carbon black; the heating conditions include heating the mixture to 1000-1500 °C at a heating rate of 2-10 °C / min.

2. The preparation method according to claim 1, characterized in that, In the mixing step, the mixture is in powder form.

3. The preparation method according to claim 1, characterized in that, In the mixing step, the bamboo is selected from at least one of arrow bamboo, moso bamboo, purple bamboo, palm bamboo, bitter bamboo, and rigid bamboo.

4. The preparation method according to claim 3, characterized in that, The carbon source includes the above-ground stems of bamboo.

5. The preparation method according to claim 1, characterized in that, In the mixing step, the particle size of the mixture is 200-300 mesh.

6. The preparation method according to claim 1, characterized in that, In the mixing step, the bamboo particles are 200-300 mesh.

7. The preparation method according to claim 1, characterized in that, The particle size of the nitrogen-doped modifier is 200-300 mesh.

8. The preparation method according to claim 1, characterized in that, In the heating step, the mixture is heated in a nitrogen atmosphere.

Images