Titanium disulfide / iron nitrogen doped carbon nanotube composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of preparation of carbon nanotubes by a catalytic pyrolysis method, in particular to a titanium disulfide / iron nitrogen doped carbon nanotube composite material as well as a preparation method and application thereof. The preparation method is divided into two parts, wherein in the first part, the iron-nitrogen-doped carbon nanotubes (FeNCNTs) loaded iron nanoparticles are prepared through a high-temperature cracking method in combination with an acid treatment measure; the first part is titanium disulfide / iron nitrogen doped carbon nanotube composite material (TiS2 atFeNCNTs), the second part is titanium disulfide / iron nitrogen doped carbon nanotube composite material (TiS2 atFeNCNTs) obtained through a solvothermal method and a high-temperature solid-phase synthesis method, the titanium disulfide / iron nitrogen doped carbon nanotube composite material can replace expensive carbon nanotubes, the use specific capacity of titanium disulfide under high power is improved, and the titanium disulfide / iron nitrogen doped carbon nanotube composite material has the advantages of being low in cost, easy to put into production and easy to implement.

Description

Technical Field

[0001] This invention relates to the field of carbon nanotube preparation technology by catalytic pyrolysis, and in particular to a titanium disulfide / iron-nitrogen-doped carbon nanotube composite material, its preparation method, and its application. Background Technology

[0002] With the escalating energy crisis and environmental pollution, coupled with the vigorous development of the new energy industry, new energy vehicles have become the preferred alternative to gasoline-powered vehicles. Among these, lithium-ion batteries are widely used in electric vehicles, energy storage power stations, and other fields due to their advantages such as high energy density, long lifespan, low self-discharge rate, and lack of memory effect.

[0003] TiS2 is a typical layered transition metal sulfide with an interlayer spacing of approximately 0.57 nm, while the radius of a lithium ion is only 0.076 nm. This provides ample space for lithium ion insertion and extraction, resulting in high theoretical specific capacity and high conductivity. Furthermore, compared to other transition metal disulfides, it is lighter and less expensive. However, titanium disulfide electrodes are prone to surface passivation, structural deformation, and lithium dendrite formation. Therefore, carbon materials such as carbon nanotubes can be introduced into titanium disulfide to address the volume changes caused by lithium insertion and extraction, thereby improving battery performance.

[0004] To address the above problems, this invention employs a catalytic pyrolysis method to prepare low-cost iron-nitrogen-doped carbon nanotubes, which can replace the expensive carbon nanotubes on the market. The main focus is on constructing a three-dimensional conductive network of the material and improving the electrochemical performance of TiS2 by introducing carbon nanotubes, thereby improving the electronic conductivity, ion diffusion rate and various electrode surface properties of TiS2. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a titanium disulfide / iron-nitrogen-doped carbon nanotube composite material, its preparation method, and its applications. The preparation method comprises two parts: the first part involves preparing nitrogen-doped carbon nanotubes (FeNCNTs) loaded with iron nanoparticles via a high-temperature pyrolysis method combined with acid treatment; the second part involves obtaining the titanium disulfide / iron-nitrogen-doped carbon nanotube composite material (TiS2@FeNCNTs) via a solvothermal method and a high-temperature solid-state synthesis method. This invention can replace expensive carbon nanotubes, improve the specific capacity of titanium disulfide at high power, and features low cost, ease of production, and ease of implementation.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing titanium disulfide / iron-nitrogen-doped carbon nanotube composite materials, comprising the following steps: 1) Melamine, ferrous sulfate and ethanol were mixed and ground to obtain the precursor; 2) Calcine the precursor described in step 1) to obtain Fe / FeNCNTs; 3) The Fe / FeNCNTs obtained in step 2) are subjected to acid treatment to obtain FeNCNTs; 4) The FeNCNTs, titanium tetrachloride, carbon disulfide, octadecene and oleylamine obtained in step 3) are mixed and subjected to a hydrothermal reaction to obtain a hydrothermal reaction material; 5) Centrifuge and dry the hydrothermal reaction material obtained in step 4) to obtain the precipitate precursor; 6) The precipitated precursor described in step 5) is subjected to high-temperature treatment to obtain titanium disulfide / iron nitrogen doped carbon nanotube composite material.

[0007] Preferably, in step 1), the mass ratio of melamine, ferrous sulfate, and ethanol is 3.2g:0.4g:20ml. The grinding time is 30 minutes; The grinding process also includes drying to obtain a precursor. The drying temperature is 60°C and the drying time is 12 hours.

[0008] Preferably, the calcination conditions in step 2) include: a first-stage calcination temperature of 500°C for 1 hour, and a second-stage calcination temperature of 900°C for 2 hours; The volume ratio of hydrogen to argon is 5:95.

[0009] Preferably, the acid treatment conditions in step 3) include: acid treatment with an excess of 10% dilute sulfuric acid at a temperature of 60°C for 24 hours.

[0010] Preferably, in step 4), the mass ratio of FeNCNTs, titanium tetrachloride, carbon disulfide, octadecene, and oleylamine is 0.2g:3.79g:1.52g:50ml:10ml.

[0011] Preferably, the conditions for the hydrothermal reaction in step 4) include: a temperature of 200°C and a time of 8 hours.

[0012] Preferably, the centrifugation conditions in step 5) include: a rotation speed of 8000~10000 rpm and a time of 5 min; The drying conditions include vacuum drying at 80°C for 10 hours.

[0013] Preferably, the conditions for the high-temperature treatment in step 6) include: high-temperature treatment in a hydrogen and argon atmosphere for 2 hours at a temperature of 600°C.

[0014] The present invention also provides a titanium disulfide / iron-nitrogen-doped carbon nanotube composite material prepared by the preparation method described above.

[0015] The present invention also provides the application of the titanium disulfide / iron-nitrogen-doped carbon nanotube composite material described in the above technical solution in the preparation of high-power batteries as a negative electrode material.

[0016] The beneficial effects of this invention are: This invention employs carbon coating as the surface treatment, which does not affect the crystal structure of titanium disulfide (TiS2). Low-cost iron-nitrogen-doped carbon nanotubes are prepared using a catalytic pyrolysis method to replace commercially available, expensive carbon nanotubes.

[0017] Furthermore, iron-nitrogen-doped carbon nanotubes not only possess a one-dimensional tubular structure but also have active sites introduced by iron-nitrogen doping. These carbon nanotubes have a cost as low as 0.5 yuan / g and can be used to construct low-cost three-dimensional conductive network structures of titanium disulfide (TiS2), thereby promoting the application of titanium disulfide anode materials in high-power batteries.

[0018] This invention is characterized by low cost, easy production, and easy implementation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0020] Figure 1 Here is the XRD pattern of Embodiment 1 in this invention; Figure 2 This is a graph showing the electrochemical performance test results of Example 1 in this invention. Detailed Implementation

[0021] This invention provides a method for preparing titanium disulfide / iron-nitrogen-doped carbon nanotube composite materials, comprising the following steps: 1) Melamine, ferrous sulfate and ethanol were mixed and ground to obtain the precursor; 2) Calcine the precursor described in step 1) to obtain Fe / FeNCNTs; 3) The Fe / FeNCNTs obtained in step 2) are subjected to acid treatment to obtain FeNCNTs; 4) The FeNCNTs, titanium tetrachloride, carbon disulfide, octadecene and oleylamine obtained in step 3) are mixed and subjected to a hydrothermal reaction to obtain a hydrothermal reaction material; 5) Centrifuge and dry the hydrothermal reaction material obtained in step 4) to obtain the precipitate precursor; 6) The precipitated precursor described in step 5) is subjected to high-temperature treatment to obtain titanium disulfide / iron nitrogen doped carbon nanotube composite material.

[0022] This invention involves mixing and grinding melamine, ferrous sulfate, and ethanol to obtain a precursor. In this invention, the preferred mass ratio of melamine, ferrous sulfate, and ethanol is 3.2 g:0.4 g:20 ml. The preferred grinding time is 30 min. Furthermore, the grinding process preferably includes drying to obtain the precursor; the preferred drying temperature is 60°C, and the preferred drying time is 12 h.

[0023] This invention involves calcining the precursor to obtain Fe / FeNCNTs. Preferably, the calcination conditions include: a first-stage calcination at 500°C for 1 hour, and a second-stage calcination at 900°C for 2 hours. The preferred volume ratio of hydrogen to argon is 5:95.

[0024] This invention involves acid treatment of the Fe / FeNCNTs to obtain FeNCNTs. The preferred acid treatment conditions include: using an excess of 10% dilute sulfuric acid at a temperature of 60°C for 24 hours. Using an excess of dilute sulfuric acid at 60°C ensures the removal of a large number of unstable metal particles from the surface.

[0025] This invention involves mixing FeNCNTs, titanium tetrachloride, carbon disulfide, octadecene, and oleylamine, followed by a hydrothermal reaction to obtain a hydrothermal reaction mixture. In this invention, the preferred mass ratio of FeNCNTs, titanium tetrachloride, carbon disulfide, octadecene, and oleylamine is 0.2 g:3.79 g:1.52 g:50 ml:10 ml. The preferred conditions for the hydrothermal reaction are a temperature of 200°C and a time of 8 hours. This invention also preferably involves ultrasonically dispersing the FeNCNTs, titanium tetrachloride, carbon disulfide, octadecene, and oleylamine. The preferred ultrasonic conditions are a power of 50 W and a time of 15 minutes. This invention uses octadecene as a solvent and oleylamine as a surfactant, resulting in uniformly dispersed particles without agglomeration. The power and time of ultrasonic dispersion ensure uniform ultrasonic dispersion of the iron-nitrogen-doped carbon nanotubes.

[0026] This invention centrifuges and dries the hydrothermal reaction material to obtain a precipitate precursor. Preferably, the centrifugation conditions include a rotation speed of 8000-10000 rpm and a time of 5 minutes. Preferably, the drying conditions include vacuum drying at 80°C for 10 hours, with the pressure during vacuum drying below -1.0 MPa.

[0027] This invention involves subjecting the precipitated precursor to high-temperature treatment to obtain a titanium disulfide / iron-nitrogen-doped carbon nanotube composite material. Preferably, the high-temperature treatment conditions include: high-temperature treatment in a hydrogen and argon atmosphere for 2 hours at a temperature of 600°C. Preferably, a hydrogen-argon mixture is introduced into the tubular furnace for 20-40 minutes before the high-temperature treatment, and the hydrogen-argon mixture is continuously introduced during calcination to ensure an inert reaction environment and prevent oxidation.

[0028] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0029] Example 1 A method for preparing a titanium disulfide / iron-nitrogen-doped carbon nanotube composite material comprises the following steps: (1) Fe / FeNCNTs were prepared by catalytic pyrolysis. Melamine and ferrous sulfate were ground evenly in ethanol and dried to obtain a precursor. The precursor was then placed in a ceramic boat and calcined at 500°C for 1 h in a hydrogen-argon mixed atmosphere, and then calcined at 700°C or 900°C for 2 h to prepare Fe / FeNCNTs, which were named 700-Fe / FeNCNTs and 900-Fe / FeNCNTs, respectively. (2) Preparation of FeNCNTs by acid treatment: Fe / FeNCNTs are added to excess dilute sulfuric acid for acid treatment to obtain FeNCNTs; (3) Preparation of TiS2@FeNCNTs precursor by solvothermal method: FeNCNTs, TiCl4, and CS2 were uniformly dispersed in octadecene and oleylamine; the solution was placed in a hydrothermal reactor at 200℃ for 8 h, and the precipitated precursor was obtained by centrifugation; (4) High-temperature solid-state synthesis method to prepare TiS2@FeNCNTs: The precursor powder was heated in a tube furnace at 600℃ for 2h (5% H2+Ar) to obtain the final product TiS2@FeNCNTs; the TiS2@FeNCNTs obtained by adding 700-FeNCNTs was named 700-TiS2; the TiS2@FeNCNTs obtained by adding 900-FeNCNTs was named 900-TiS2.

[0030] (5) Assemble the half cell: Weigh 700-TiS2 or 900-TiS2, conductive carbon black and polytetrafluoroethylene in a mass ratio of 8:1:1, grind and disperse them thoroughly until they become a uniform coatable slurry; use an adjustable scraper to uniformly coat the ground mixed slurry with a thickness of 60μm on a clean and flat copper foil to make a current collector; then place the coated current collector in a vacuum drying oven for drying; use a slicing machine to punch the dried current collector into a circular electrode sheet with a diameter of 12mm; transfer the prepared electrode sheet to a high-purity argon glove box for assembling the coin cell half cell, and let it stand for a period of time for electrochemical performance testing.

[0031] Performance testing: The phase characteristics of 700-TiS2 and 900-TiS2 were characterized, and the electrochemical performance of the half-cells was tested.

[0032] The XRD pattern of the product in this embodiment is shown below. Figure 1 .from Figure 1 The diffraction peaks of TiS2 are clearly sharp and match very well with the peaks in the standard PDF card of TiS2 (JCPDS:15-0853), indicating that both 700-TiS2 and 900-TiS2 contain relatively pure and well-crystallized TiS2 material. However, the carbon nanotube peaks near 26° in 900-TiS2 are sharper than the corresponding carbon nanotube peaks in 700-TiS2, indicating that FeNCNTs prepared at 900°C have better crystallinity.

[0033] The electrochemical performance graph of the product in this embodiment is shown below. Figure 2 . Figure 2 The charging current densities were 0.1, 0.2, 0.5, 1, 2, and 5 A·g, respectively. -1 Each current density cycle was performed 5 times, and finally the current density was adjusted back to 0.1 A·g. -1 .from Figure 2 It can be seen that the specific charging capacity of 900-TiS2 is higher than that of 700-TiS2. When the charging current density is 1 A·g... -1 At that time, the average charge specific capacity of 900-TiS2 was 490.6 mAh·g. -1 It is 700-TiS2 (377.7 mAh·g) -1 1.3 times that of ).

[0034] This invention addresses the drawbacks of titanium disulfide, such as surface passivation, structural deformation, and susceptibility to lithium dendrite formation, by adding low-cost conductive carbon nanotubes to improve its electrochemical performance. To mitigate the volume expansion issue of titanium disulfide (TiS2) anode materials, this invention employs carbon coating as the surface treatment, which does not affect the crystal structure of titanium disulfide. Low-cost iron-nitrogen-doped carbon nanotubes are prepared using a catalytic pyrolysis method to replace commercially available, expensive carbon nanotubes. Furthermore, these iron-nitrogen-doped carbon nanotubes not only possess a one-dimensional tubular structure but also have active sites provided by iron-nitrogen doping. The cost of these carbon nanotubes is as low as 0.5 yuan / g, allowing for the construction of low-cost three-dimensional conductive network structures for titanium disulfide (TiS2), thereby promoting the application of titanium disulfide anode materials in high-power batteries. This invention is characterized by low cost, ease of production, and ease of implementation.

[0035] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a titanium disulfide / iron-nitrogen-doped carbon nanotube composite material, characterized in that, Includes the following steps: 1) Melamine, ferrous sulfate and ethanol were mixed and ground to obtain the precursor; 2) Calcine the precursor described in step 1) to obtain Fe / FeNCNTs; 3) The Fe / FeNCNTs obtained in step 2) are subjected to acid treatment to obtain FeNCNTs; 4) The FeNCNTs, titanium tetrachloride, carbon disulfide, octadecene and oleylamine obtained in step 3) are mixed and subjected to a hydrothermal reaction to obtain a hydrothermal reaction material; 5) Centrifuge and dry the hydrothermal reaction material obtained in step 4) to obtain the precipitate precursor; 6) The precipitated precursor described in step 5) is subjected to high-temperature treatment to obtain titanium disulfide / iron nitrogen doped carbon nanotube composite material.

2. The preparation method according to claim 1, characterized in that, In step 1), the mass ratio of melamine, ferrous sulfate, and ethanol is 3.2g:0.4g:20ml. The grinding time is 30 minutes; The grinding process also includes drying to obtain a precursor. The drying temperature is 60°C and the drying time is 12 hours.

3. The preparation method according to claim 1, characterized in that, Step 2) The calcination conditions include: calcination is carried out in a hydrogen and argon atmosphere, the first stage calcination temperature is 500℃ and the time is 1h, and the second stage calcination temperature is 900℃ and the time is 2h. The volume ratio of hydrogen to argon is 5:

95.

4. The preparation method according to claim 1, characterized in that, Step 3) The acid treatment conditions include: using an excess of 10% dilute sulfuric acid for acid treatment at a temperature of 60°C for 24 hours.

5. The preparation method according to claim 1, characterized in that, Step 4) The mass ratio of FeNCNTs, titanium tetrachloride, carbon disulfide, octadecene, and oleylamine is 0.2g:3.79g:1.52g:50ml:10ml.

6. The preparation method according to claim 1, characterized in that, Step 4) The conditions for the hydrothermal reaction include: a temperature of 200°C and a time of 8 hours.

7. The preparation method according to claim 1, characterized in that, Step 5) The centrifugation conditions include: a rotation speed of 8000~10000 rpm and a time of 5 min; The drying conditions include vacuum drying at 80°C for 10 hours.

8. The preparation method according to claim 1, characterized in that, Step 6) The conditions for the high-temperature treatment include: high-temperature treatment in a hydrogen and argon atmosphere for 2 hours at a temperature of 600°C.

9. A titanium disulfide / iron-nitrogen-doped carbon nanotube composite material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the titanium disulfide / iron-nitrogen-doped carbon nanotube composite material according to claim 9 in the preparation of high-power batteries as a negative electrode material.

Images