A method for preparing carbon nanotube-graphene hybrid material

Abstract

The invention discloses a preparation method of a carbon nanotube-graphene hybrid material, which relates to the technical field of carbon nanotubes. The method comprises the following steps: uniformly mixing a carbon source, a catalyst, and a promoter by means of a stirrer; preheating the carbon source mixture by means of a syringe pump under the action of a carrier gas, blending the mixture into an ultrasonic atomizing device, and introducing the mixture into a vertical tubular synthesis furnace for synthesis; the formed carbon nanotube gel film adheres to a cold furnace wall to form a network structure, and after the network is formed, the carbon source concentration changes, and a carbon nanotube-graphene hybrid is formed on the surface of the carbon nanotubes; and the carbon network is cleaned by means of a lower cleaning mechanism to obtain the carbon nanotube-graphene hybrid. The method has the beneficial effect that a nanomaterial with a carbon nanotube-graphene hybrid structure is prepared by improving the floating catalysis process, the preparation method is easy to carry out mass production, and the product can be added to a lithium-ion battery to improve the rate and cycle performance of the battery, thus having a very good prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon nanotubes, and in particular to a method for preparing a carbon nanotube-graphene hybrid material. Background Art

[0002] Carbon nanotubes are one-dimensional hollow tubular structures with excellent physical and chemical properties. Their tensile strength can reach 100 times that of steel, their density is 1 / 2 that of aluminum, their thermal conductivity can reach 3000W / mK, and their electrical conductivity is very excellent.

[0003] Graphene is composed of single or multiple layers of graphite atoms stacked together and has excellent physical and chemical properties.

[0004] Regarding the research on carbon nanotube-graphene hybrid materials, the current preparation methods mainly include a solid template catalyst synthesis process for preparing carbon nanotube-graphene hybrids, such as the one described in Tsinghua University's patent (application number: 201210230241.6). This method has difficulty removing the inorganic catalyst template. Another method uses a self-assembly method to combine carbon nanotubes grafted with functional groups with graphene, but the prepared carbon nanotube-graphene bonding strength is insufficient. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a carbon nanotube-graphene hybrid material in order to solve the above problems. The prepared nano hybrid material has a specific surface area of ​​50-1000m 2 / g, the diameter of carbon nanotubes is 1-100nm, the number of graphene layers is 5-10 layers, and the diameter of graphene sheets is less than 1μm.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A method for preparing a carbon nanotube-graphene hybrid material, wherein the specific surface area of ​​the prepared carbon nanotube-graphene nanohybrid material is 50-1000m 2 / g, the carbon nanotube diameter is 1-100nm, the number of graphene layers is 5-10 layers, and the graphene size is less than 1μm; the preparation method comprises the following specific steps:

[0008] Step S1: mixing the carbon source, catalyst and promoter uniformly with a stirrer;

[0009] Step S2: The carbon source mixture is preheated and blended in an ultrasonic atomization device under the action of a carrier gas using a syringe pump, and then introduced into a vertical tubular synthesis furnace for synthesis. The synthesis process is divided into two stages: one is the carbon nanotube synthesis stage, and the other is the graphene hybrid formation stage;

[0010] Step S3: controlling the temperature of the carbon nanotube synthesis section to 1200-1500° C., controlling the inner wall of the graphene hybrid formation section to -5-80° C., and controlling the pressure in the furnace to 5-20 KPa;

[0011] Step S4: Controlling the synthesis time to be 30-200 minutes, the formed carbon nanotube gel film adheres to the cold furnace wall to form a network structure. After the network is formed, the carbon source concentration changes, and a carbon nanotube-graphene hybrid is formed on the surface of the carbon nanotube;

[0012] Step S5: using the lower cleaning mechanism to clean the carbon mesh to obtain a carbon nanotube-graphene hybrid;

[0013] Step S6: dispersing the formed carbon nanotube-graphene hybrid in NMP or water using a dispersant, adding the hybrid to the positive and negative electrode materials of a lithium-ion battery, and testing the electrochemical performance of the battery.

[0014] Preferably, the carbon source in step S1 includes ethanol, acetone, benzene, toluene, and xylene; the catalyst includes ferrocene, cobaltocene, and nickelocene; and the promoter is sulfur-containing organic and inorganic substances, including thiophene, carbon disulfide, and sulfur powder.

[0015] Preferably, the mass ratio of the carbon source, catalyst and promoter in step S1 is (90-95): (5-10): (5-10).

[0016] Preferably, the carrier gas in step S2 is hydrogen with a flow rate of 10-100m 3 / h.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention improves the floating catalytic chemical vapor deposition process to prepare a nanomaterial with a carbon nanotube-graphene hybrid structure. There is no inorganic catalyst, and the catalyst is formed in situ. The preparation method is easy to carry out mass production. Adding this product to lithium-ion batteries can improve the battery's rate and cycle performance, and has very good prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1The present invention provides a scanning electron microscope (SEM) photograph of a carbon nanotube-graphene hybrid material prepared by using the method for preparing a carbon nanotube-graphene hybrid material of the present invention.

[0021] Figure 2 、 Figure 3 The present invention is a transmission electron microscope (TEM) photograph of a single-walled carbon nanotube of a carbon nanotube-graphene hybrid material prepared by using the method for preparing a carbon nanotube-graphene hybrid material of the present invention.

[0022] Figure 4 It is a structural schematic diagram of a vertical tubular synthesis furnace used in the method for preparing a carbon nanotube-graphene hybrid material described in the present invention.

[0023] Figure 5 The carbon nanotube graphene hybrid material prepared by the preparation method of the carbon nanotube graphene hybrid material of the present invention and the control group carbon black as a conductive agent are reacted in the LiNi 0.5 Co 0.2 Mi 0.3 Rate performance comparison in O2.

[0024] Figure 6 The carbon nanotube graphene hybrid material prepared by the preparation method of the carbon nanotube graphene hybrid material of the present invention and the control group carbon black as a conductive agent are reacted in the LiNi 0.5 Co 0.2 Mi 0.3 Comparison of cycling performance in O2.

[0025] The following are the descriptions of the reference numerals:

[0026] 1. Feed pipe; 2. Air inlet pipe; 3. Flow meter; 4. Preheater; 5. Mixer; 6. Ultrasonic atomization device; 7. Upper cleaning mechanism; 8. Synthesis furnace body; 9. Cooling synthesis section; 10. Lower cleaning mechanism; 11. Gas-solid separator. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings:

[0028] A method for preparing carbon nanotube-graphene hybrid materials is an improved floating chemical vapor deposition method. The specific surface area of ​​the carbon nanotube-graphene nanohybrid materials prepared by the method is 50-1000m 2 / g, the carbon nanotube diameter is 1-100nm, the number of graphene layers is 5-10 layers, and the graphene size is less than 1μm; the preparation method comprises the following specific steps:

[0029] Step S1: mixing the carbon source, catalyst and promoter uniformly with a stirrer;

[0030] Step S2: The carbon source mixture is preheated and blended in an ultrasonic atomization device under the action of a carrier gas using a syringe pump and then introduced into a vertical tubular synthesis furnace for synthesis; Figure 4 As shown, the vertical tubular synthesis furnace includes a synthesis furnace body 8, the top of which is provided with a feed pipe 1 for mixed raw materials and an inlet pipe 2 for carrier gas. After the two are combined, they enter the synthesis furnace body 8 through a mixer 5. The end of the feed pipe 1 is provided with an ultrasonic atomizer 6 for vaporizing and spraying the materials. An upper cleaning mechanism 7 is provided on the inner wall of the synthesis furnace body 8. A cooling synthesis section 9, a lower cleaning mechanism 10 and a gas-solid separator 11 are provided below the synthesis furnace body 8. When using this synthesis furnace, a catalyst, a carbon source and a promoter are mixed to form a raw material. The mixed raw material and carrier gas are atomized by the atomizer and then introduced into the synthesis furnace. The synthesis process is divided into two sections, one for carbon nanotube synthesis and the other for graphene hybrid formation.

[0031] Step S3: controlling the temperature of the carbon nanotube synthesis section to 1200-1500° C., controlling the inner wall of the graphene hybrid formation section to -5-80° C., and controlling the pressure in the furnace to 5-20 KPa;

[0032] Step S4: Controlling the synthesis time to be 30-200 minutes, the formed carbon nanotube gel film adheres to the cold furnace wall to form a network structure. After the network is formed, the carbon source concentration changes, and a carbon nanotube-graphene hybrid is formed on the surface of the carbon nanotube;

[0033] Step S5: using the lower cleaning mechanism to clean the carbon mesh to obtain a carbon nanotube-graphene hybrid;

[0034] Step S6: dispersing the formed carbon nanotube-graphene hybrid in NMP or water using a dispersant, adding the mixture to the positive and negative electrode materials of a lithium-ion battery, and testing the electrochemical performance of the battery.

[0035] The carbon source in step S1 includes ethanol, acetone, benzene, toluene, and xylene; the catalyst includes ferrocene, cobaltocene, and nickelocene; and the promoter is sulfur-containing organic and inorganic substances, including thiophene, carbon disulfide, and sulfur powder.

[0036] The mass ratio of the carbon source, catalyst and promoter in step S1 is (90-95): (5-10): (5-10).

[0037] The carrier gas in step S2 is hydrogen, and its flow rate is 10-100m 3 / h. .

[0038] Performance testing:

[0039] ① The catalyst ferrocene (4) and the promoter thiophene (4) were dissolved in the carbon source ethanol (92) according to the mass ratio; the synthesis furnace temperature was 1350 ° C, and when the material was fed, the injection pump was used to control the feeding speed of the raw material to 50 mL / h, and the hydrogen flow rate was 20m 3 / h, using a chiller to control the inner wall temperature at 50 ° C, the synthesis time is 30 min, using the lower cleaning mechanism to clean the product, the product weight is 20g / h, the specific surface area of ​​the test material is 150m 2 / g.

[0040] ② SEM and TEM tests of the generated carbon nanotube-graphene hybrid powders are shown in Figure 1 、 Figure 2 、 Figure 3 TEM showed that the diameter and graphene sheet diameter were 45nm and 0.1μm respectively, and the number of graphene layers was 3-5.

[0041] ③ The prepared carbon nanotube-graphene hybrid was dispersed in NMP solution, using PVP K30 as a dispersant. The solid content of the dispersed carbon nanotube-graphene was 4%. 0.5 Co 0.2 Mi 0.3 O2: PVDF5130: carbon nanotube-hybrid was prepared into slurry in NMP solution at a mass ratio of 94::4:2. The slurry was coated on aluminum foil and baked in an oven to form a pole piece. The electrochemical performance was tested with 1 mol / L LiPF6 as the electrolyte and metallic lithium as the reference electrode. At the same time, a control group was set up in which conductive carbon black replaced the carbon nanotube-graphene hybrid. The test rate and cycle performance are shown in Fig. Figure 5 and Figure 6 , compared with the control group, the rate and cycle performance have obvious advantages.

[0042] The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, and these changes and improvements shall fall within the scope of the invention claimed for protection.

Claims

1. A method for preparing a carbon nanotube-graphene hybrid material, characterized in that: The specific surface area of ​​the carbon nanotube-graphene nanohybrid material prepared is 50-1000m 2 / g, the carbon nanotube diameter is 1-100nm, the number of graphene layers is 5-10 layers, and the graphene size is less than 1μm; the preparation method comprises the following specific steps: Step S1: mixing the carbon source, catalyst, and promoter uniformly by a stirrer, wherein the catalyst includes ferrocene, cobaltocene, and nickelocene; Step S2: The carbon source mixture is preheated and blended in an ultrasonic atomization device under the action of a carrier gas using a syringe pump, and then introduced into a vertical tubular synthesis furnace for synthesis. The synthesis process is divided into two stages: one is the carbon nanotube synthesis stage, and the other is the graphene hybrid formation stage; Step S3: controlling the temperature of the carbon nanotube synthesis section to 1200-1500° C., controlling the inner wall of the graphene hybrid formation section to -5-80° C., and controlling the pressure in the furnace to 5-20 KPa; Step S4: Controlling the synthesis time to be 30-200 minutes, the formed carbon nanotube gel film adheres to the cold furnace wall to form a network structure. After the network is formed, the carbon source concentration changes, and a carbon nanotube-graphene hybrid is formed on the surface of the carbon nanotube; Step S5: using the lower cleaning mechanism to clean the carbon mesh to obtain a carbon nanotube-graphene hybrid; Step S6: dispersing the formed carbon nanotube-graphene hybrid in NMP or water using a dispersant, adding the hybrid to the positive and negative electrode materials of a lithium-ion battery, and testing the electrochemical performance of the battery.

2. The method for preparing a carbon nanotube-graphene hybrid material according to claim 1, wherein: The carbon source in step S1 includes ethanol, acetone, benzene, toluene, and xylene; the accelerator is sulfur-containing organic and inorganic substances, including thiophene, carbon disulfide, and sulfur powder.

3. The method for preparing a carbon nanotube-graphene hybrid material according to claim 1, wherein: The mass ratio of the carbon source, catalyst and promoter in step S1 is (90-95): (5-10): (5-10).

4. The method for preparing a carbon nanotube-graphene hybrid material according to claim 1, wherein: The carrier gas in step S2 is hydrogen, and its flow rate is 10-100m 3 / h.

Images