Preparation method of high temperature carbonized nitrogen doped core-shell structure activated carbon composite electrode

Abstract

The present invention discloses a method for preparing a nitrogen-doped core-shell structure activated carbon electrode material, which adopts the following technical scheme: (1) dissolving graphite oxide in deionized water, and then directly adding glucose powder to the graphene oxide solution; (2) placing the mixed solution obtained in step (1) in a reactor, and reacting at 160-190°C for 12-24 h; after the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor, which is then heated to 800°C at a heating rate of 3°C / min-5°C / min under an inert atmosphere, and calcined for 3-6 h to obtain a nitrogen-doped core-shell structure activated carbon supercapacitor electrode material. In step (1), the concentration of the graphene oxide solution is 0.3-0.7 mg / mL, the concentration of the glucose solution is 30-350 mg / mL, and the mass ratio of graphite oxide to glucose is 1:100-1:300. The present invention can improve the capacitance performance of a single material. As a supercapacitor electrode material, its specific capacitance is as high as 389 F / g at 0.1 A / g, showing high electrochemical performance.

Description

Technical Field

[0001] The invention belongs to the field of nano composite material preparation, in particular to a method for preparing a high-temperature carbonized nitrogen doped core-shell structure activated carbon composite electrode. Background Art

[0002] The rapid development of portable electronic devices such as mobile phones, laptops, digital cameras, and electric vehicles is highly dependent on the development of energy storage devices. In the research on high-performance, low-cost and environmentally friendly energy storage devices, supercapacitors have obvious advantages in energy storage devices due to their excellent performance. Electrode materials, as the core components of supercapacitors, affect the electrochemical behavior of supercapacitors. Among them, carbon electrode materials are favored by energy storage devices because of their low cost, controllable pore structure, large specific surface area, high chemical / thermal stability and excellent conductivity. Despite their wide application, some energy storage properties of carbon materials, such as specific capacitance, rate performance, energy density, etc., need to be improved. Therefore, it is particularly important to improve the electrochemical properties of carbon materials without sacrificing the excellent double-layer capacitance performance of carbon materials themselves.

[0003] Special atmosphere heat treatment method is widely used in the preparation of atomic doped (nitrogen, nitrogen, sulfur) nanomaterials due to its unique technical advantages (such as low cost and high efficiency), aiming to introduce pseudocapacitance into the bulk material and obtain better electrochemical performance. At present, heteroatom doping has a wide range of applications in supercapacitors, lithium-ion batteries, zinc-ion batteries, photocatalysis, photoelectrocatalysis and other fields. Among them, nitrogen atom doping is the most common atomic doping method.

[0004] Studies have found that nitrogen doping can effectively improve the single double-layer capacitance of carbon electrode materials and change the wettability of carbon electrode materials with electrolytes. However, there are few reports on heteroatom doping of graphite oxide and glucose composites through inert atmosphere. Glucose is a common biomass raw material that is easy to obtain. Summary of the invention

[0005] The present invention uses glucose and graphene oxide raw materials prepared by a modified Hummers method to prepare nitrogen-doped core-shell structure activated carbon electrode materials through a hydrothermal-calcination two-step method, and uses inert gas nitrogen gas as a calcination atmosphere and a nitrogen source at the same time. The double-layer capacitance characteristics of the carbon material itself in the composite material and the pseudocapacitance characteristics of the nitrogen element have a synergistic effect, which can improve the capacitance performance of a single material. As a supercapacitor electrode material, its specific capacitance is as high as 389 F / g at 0.1 A / g, showing high electrochemical performance.

[0006] The present invention aims to provide a method for preparing a nitrogen-doped core-shell structured activated carbon electrode material, which adopts the following technical scheme:

[0007] (1) Dissolve graphene oxide in deionized water and then add glucose powder directly to the graphene oxide solution;

[0008] (2) placing the mixed solution obtained in step (1) in a reactor and reacting it at 160-190 °C for 12-24 h; after the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor, which is then heated to 800 °C in an inert atmosphere at a heating rate of 3 °C / min-5 °C / min, and calcined for 3-6 h to obtain a nitrogen-doped core-shell structured activated carbon supercapacitor electrode material.

[0009] In step (1), the concentration of the graphene oxide solution is 0.3-0.7 mg / mL, the concentration of the glucose solution is 30-350 mg / mL, and the mass ratio of graphene oxide to glucose is 1:100-1:300.

[0010] Beneficial effects of the present invention:

[0011] (1) The method is simple and easy to operate, does not require pH adjustment, and biomass glucose raw materials are readily available, making it easy to implement industrially.

[0012] (2) The nitrogen-doped core-shell structured activated carbon supercapacitor electrode material prepared by the present invention has excellent capacitance performance and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The X-ray diffraction (XRD) spectrum of the nitrogen-doped core-shell structured activated carbon electrode material prepared in Example 1 of the present invention shows that the diffraction peak at about 24.9° can be attributed to the (002) crystal plane of graphene.

[0014] Figure 2 This is a scanning electron microscope (SEM) photograph (scale 1 μm) of the nitrogen-doped core-shell structured activated carbon electrode material prepared in Example 1 of the present invention. The SEM image clearly shows that the product is a cellular substance.

[0015] Figure 3 This is a transmission electron microscope (TEM) photograph (scale 200 nm) of the nitrogen-doped core-shell structured activated carbon electrode material prepared in Example 1 of the present invention. The TEM image clearly shows that graphene wraps the carbon material derived from glucose at high temperature, and the core-shell structure is very clear.

[0016] Figure 4 The charge and discharge curve of the nitrogen-doped core-shell structured activated carbon electrode material prepared in Example 1 of the present invention tested in 1 M H2SO4 electrolyte has a voltage range of -0.2-0.8. DETAILED DESCRIPTION

[0017] The present invention is described in detail below in conjunction with the embodiments so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.

[0018] Embodiment 1:

[0019] (1) Add 300 mg of glucose to 30 ml of 0.5 mg / ml graphene oxide solution.

[0020] (2) The mixed solution obtained in step (1) is placed in a reactor and reacted at 160°C for 1 h. After the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor, which is then heated to 800°C at a heating rate of 3°C / min under an inert atmosphere and calcined for 3 h to obtain a nitrogen-doped core-shell structured activated carbon supercapacitor electrode material.

[0021] Figure 1 The X-ray diffraction (XRD) spectrum of the nitrogen-doped core-shell structured activated carbon electrode material prepared in this example shows that the diffraction peak at about 24.9° can be attributed to the (002) crystal plane of graphene.

[0022] Figure 2 This is a scanning electron microscope (SEM) photograph (scale 1 μm) of the nitrogen-doped core-shell structured activated carbon electrode material prepared in this example. The SEM image clearly shows that the product is a cellular substance.

[0023] Figure 3 This is a transmission electron microscope (TEM) photograph (scale 200 nm) of the nitrogen-doped core-shell structured activated carbon electrode material prepared in this example. The TEM image clearly shows that graphene wraps the carbon material derived from glucose at high temperature, and the core-shell structure is very clear.

[0024] Figure 4 This is the charge and discharge curve of the nitrogen-doped core-shell structured activated carbon electrode material prepared in this example tested in 1 M H2SO4 electrolyte, with a voltage range of -0.2-0.8.

[0025] Embodiment 2:

[0026] (1) Add 300 mg of glucose to 30 ml of 0.5 mg / ml graphene oxide solution.

[0027] (2) The mixed solution obtained in step (1) is placed in a reactor and reacted at 180°C for 1 h. After the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor, which is then heated to 800°C at a heating rate of 3°C / min under an inert atmosphere and calcined for 3 h to obtain a nitrogen-doped core-shell structured activated carbon supercapacitor electrode material.

[0028] Embodiment 3:

[0029] (1) Add 450 mg of glucose to 30 ml of 0.5 mg / ml graphene oxide solution.

[0030] (2) The mixed solution obtained in step (1) is placed in a reactor and reacted at 180°C for 1 h. After the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor, which is then heated to 800°C at a heating rate of 3°C / min under an inert atmosphere and calcined for 3 h to obtain a nitrogen-doped core-shell structured activated carbon supercapacitor electrode material.

[0031] Embodiment 4:

[0032] (1) Add 300 mg of glucose to 30 ml of 0.5 mg / ml graphene oxide solution.

[0033] (2) The mixed solution obtained in step (1) is placed in a reactor and reacted at 160°C for 1 h. After the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor, which is then heated to 800°C at a heating rate of 3°C / min under an inert atmosphere and calcined for 3 h to obtain a nitrogen-doped core-shell structured activated carbon supercapacitor electrode material.

[0034] Embodiment 5:

[0035] (1) Add 450 mg of glucose to 30 ml of 0.5 mg / ml graphene oxide solution.

[0036] (2) The mixed solution obtained in step (1) is placed in a reactor and reacted at 160°C for 1 h. After the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor, which is then heated to 800°C at a heating rate of 5°C / min under an inert atmosphere and calcined for 3 h to obtain a nitrogen-doped core-shell structured activated carbon supercapacitor electrode material.

[0037] Embodiment 6:

[0038] (1) Add 750 mg of glucose to 30 ml of 0.5 mg / ml graphene oxide solution.

[0039] (2) The mixed solution obtained in step (1) is placed in a reactor and reacted at 180°C for 1 h. After the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor, which is then heated to 800°C at a heating rate of 5°C / min under an inert atmosphere and calcined for 3 h to obtain a nitrogen-doped core-shell structured activated carbon supercapacitor electrode material.

Claims

1. A method for preparing a high-temperature carbonized nitrogen doped core-shell structure activated carbon composite electrode, characterized in that: The following steps are included: (1) dissolving graphene oxide in deionized water to prepare a graphene oxide solution, and then directly adding glucose powder to the graphene oxide solution; (2) placing the mixed solution obtained in step (1) in a reaction kettle and reacting at 160-190°C for 12-24 hours; after the reaction is completed and cooled, the cylindrical solid sample is separated, washed, and dried to obtain a precursor; (3) The precursor was placed in an inert nitrogen atmosphere and heated to 800 °C at a heating rate of 3 °C / min-5 °C / min. After calcination for 3-6 h, a nitrogen-doped core-shell structured activated carbon supercapacitor electrode material was obtained.

2. The method for preparing a high-temperature carbonized nitrogen doped core-shell structure activated carbon composite electrode according to claim 1, characterized in that: In step (1), the graphene oxide is obtained by oxidizing natural flake graphite using a modified Hummers method.

3. The method for preparing a high-temperature carbonized nitrogen doped core-shell structure activated carbon composite electrode according to claim 1, characterized in that: In step (1), the concentration of the graphene oxide solution is 0.3-0.7 mg / mL, the concentration of the glucose solution is 30-350 mg / mL, and the mass ratio of graphene oxide to glucose is 1:100-1:300.

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