Preparation method and application of composite carbon material

Abstract

The invention discloses a preparation method and application of a composite carbon material. The preparation method of the composite carbon material provided by the invention comprises the following steps: mixing a carbon source, an activating agent and a template agent, and carrying out carbonization reaction to obtain the sheet-shaped composite carbon material, the carbon source is rice husk carbon and coal pitch; the activating agent is potassium carbonate; the template agent is potassium chloride and nano magnesium oxide. The obtained carbon material has a large specific surface area and has high specific capacity and energy density as an electrode material of the zinc ion hybrid capacitor, and the zinc ion hybrid capacitor prepared from the carbon material has high capacity retention rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon material preparation, and in particular relates to a preparation method and application of a composite carbon material for zinc ion hybrid capacitors. Background Art

[0002] With the rapid depletion of fossil fuels and increasing energy demand, the development of clean, sustainable new energy sources has become an urgent issue. With the development of new energy sources, the demand for novel energy storage devices is increasing. Hybrid capacitors, which combine the advantages of batteries' high energy density with capacitors' long cycle life, have attracted widespread attention from researchers. Among these hybrid capacitors, zinc-ion hybrid capacitors stand out due to their zinc electrodes' low redox voltage, high theoretical capacity, low cost, safety, stability, and environmental friendliness.

[0003] Carbon materials, due to their low cost, stable physical and chemical properties, and high porosity, have become one of the most promising cathode materials for zinc-ion hybrid capacitors. However, most carbon materials suffer from limitations such as low surface area, irrational pore size distribution, and poor conductivity, limiting their further application in zinc-ion hybrid capacitors. Research has found that structural design and heteroatom doping of carbon materials can effectively address these issues. Summary of the Invention

[0004] The present invention provides a method for preparing a flaky composite carbon material and its application in zinc-ion hybrid capacitors. The resulting carbon material has a large specific surface area and can be used as an electrode material for zinc-ion hybrid capacitors, exhibiting high specific capacity and energy density. The resulting zinc-ion hybrid capacitors exhibit high capacity retention.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a composite carbon material, comprising the following steps: mixing a carbon source, an activating agent, and a template, and subjecting the mixture to a carbonization reaction to obtain a sheet-like composite carbon material;

[0007] The carbon sources are rice husk carbon and coal tar pitch;

[0008] The activator is potassium carbonate;

[0009] The template agents are potassium chloride and nano magnesium oxide.

[0010] This invention uses rice husk carbon and coal tar pitch as carbon sources, potassium carbonate as an activator, and potassium chloride and nano-magnesium oxide as templates to produce a flaky composite carbon material for zinc ion hybrid capacitors through a carbonization reaction. This material has a large specific surface area, a suitable pore size, and contains both micropores and mesopores, resulting in a high specific capacity as a positive electrode material.

[0011] The mass ratio of the rice husk carbon to the coal tar pitch is 1: (0.9-1.1), preferably 1: 1. By combining the material structures of the hard carbon of the rice husk carbon and the soft carbon of the coal tar pitch, a sheet structure composed of many flakes and particles is formed.

[0012] The mass ratio of the activator to the carbon source is (2.5-3.5): 1, preferably 3: 1. By adjusting the ratio of the two, carbon materials with different morphological characteristics, pore structure parameters and electrical storage properties can be obtained.

[0013] The mass ratio of the potassium chloride to the nano-magnesium oxide is 1:(0.9-1.1), preferably 1:1, so as to obtain a rich pore structure.

[0014] The mass ratio of the template to the carbon source is (5.9-6.1):1, preferably 6:1, which is conducive to obtaining rich and diverse pore structures.

[0015] The carbonization reaction is achieved in a one-step process under an argon atmosphere, specifically comprising two stages:

[0016] Stage 1: temperature 290-310°C, time 55-65 minutes;

[0017] The second stage: temperature is 850-860℃, time is 55-65min.

[0018] The heating rate is 4-6°C / min.

[0019] The method further includes post-processing: crushing the reaction product, adding 1-3 mol / L acid solution, stirring for 11-13 hours, then washing with 75-85°C distilled water until neutral, drying at 100-120°C for 11-13 hours, grinding, and sieving to obtain a flaky composite carbon material.

[0020] In a second aspect, the present invention also provides a composite carbon material obtained by the above preparation method.

[0021] In a third aspect, the present invention further provides a zinc ion hybrid capacitor, comprising an electrode material; the electrode material is the composite carbon material.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The flaky composite carbon material prepared by the present invention has a large specific surface area (1234m 2 / g), and can be heated in a conventional tube furnace. The preparation method is simple, the process is easy to operate, and there is no pollution.

[0024] 2. The flaky composite carbon material provided by this invention can be used as an electrode material for zinc-ion hybrid capacitors. Its specific capacity reaches 125.3 mAh / g at a current density of 0.1 A / g, corresponding to an energy density of 92.4 Wh / kg. Even at a power density of 11.2 kW / kg, its energy density remains at 34.4 Wh / kg. Furthermore, at a current density of 5 A / g, after 10,000 cycles, the capacity retention of the zinc-ion hybrid capacitor is 99.85%, and the coulombic efficiency is close to 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 These are the nitrogen adsorption-desorption isotherms of the flaky composite carbon materials prepared in Examples 1-3 of the present invention.

[0026] Figure 2 This is a transmission electron microscope photograph of the flaky composite carbon material prepared in Example 2 of the present invention.

[0027] Figure 3 The charge-discharge curves of the flaky composite carbon electrode material prepared in Examples 1-3 of the present invention in a 2 mol / L ZnSO4 electrolyte at a current density of 0.1 A / g. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to specific examples, but the present invention is not limited to the following examples.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0030] Unless otherwise specified, the reagents, materials, instruments, etc. used in the following examples can be obtained from commercial sources.

[0031] Example 1

[0032] The specific preparation process of the flaky composite carbon material SCCM5 is as follows:

[0033] (1) Pretreatment of reactants: Weigh 1 g of rice husk carbon, 1 g of coal tar, 5 g of potassium carbonate, 6 g of potassium chloride, and 6 g of nano-magnesium oxide and transfer them into a mortar and mix thoroughly to obtain a reactant;

[0034] (2) Preparation of flaky composite carbon materials: The reactants were poured into a pre-fired clean porcelain boat, and the boat was transferred to the center of a horizontal tube furnace. Under an argon atmosphere, the temperature was first increased to 300°C at a rate of 5°C / min and held at this temperature for 60 min. Then, the temperature was increased to 850°C at a rate of 5°C / min and held at this temperature for 60 min.

[0035] After the reaction is completed, the temperature naturally drops to room temperature. The obtained product is then taken out, ground and crushed, and placed in a beaker. 2 mol / L dilute hydrochloric acid is added, and then stirred with a magnetic stirrer at room temperature for 12 hours. The sample is then washed with distilled water at about 80°C until the filtrate is neutral. The washed sample is placed in a blast drying oven and dried at a constant temperature of 110°C for 12 hours, and then ground through a 325-mesh sieve to obtain a flaky composite carbon material.

[0036] The obtained flaky composite carbon material is labeled as SCCM5. SCCM5 is used as an electrode material for zinc ion hybrid capacitors. In 2 mol / L ZnSO4 electrolyte, at a current density of 0.1 A / g, its specific capacity is 82.1 mAh / g.

[0037] Example 2

[0038] The specific preparation process of the flaky composite carbon material SCCM6 is as follows:

[0039] (1) Pretreatment of the reactants: The same method as step (1) in Example 1 was used, except that 6 g of potassium carbonate was used;

[0040] (2) Preparation of sheet-like composite carbon material: The same method as step (2) in Example 1 was used.

[0041] The obtained flaky composite carbon material is labeled SCCM6. SCCM6 is used as an electrode material for zinc ion hybrid capacitors. In 2 mol / L ZnSO4 electrolyte, at a current density of 0.1 A / g, its specific capacity is 125.3 mAh / g.

[0042] Example 3

[0043] The specific preparation process of the flaky composite carbon material SCCM7 is as follows:

[0044] (1) Pretreatment of the reactants: The same method as step (1) in Example 1 was used, except that the amount of potassium carbonate used was 7 g;

[0045] (2) Preparation of sheet-like composite carbon material: The same method as step (2) in Example 1 was used.

[0046] The obtained flaky composite carbon material is labeled SCCM7. SCCM7 is used as an electrode material for zinc ion hybrid capacitors. In 2 mol / L ZnSO4 electrolyte, at a current density of 0.1 A / g, its specific capacity is 80.1 mAh / g.

[0047] Test results:

[0048] 1. Nitrogen adsorption and desorption isotherms

[0049] Depend on Figure 1It can be seen that the flaky composite carbon materials prepared in Examples 1-3 contain both micropore and mesopore structures, indicating that they have a suitable pore structure and thus have a larger specific surface area and specific capacity.

[0050] Table 1 Pore structure data of BNP-PC samples

[0051]

[0052] 2. Transmission electron microscope photos

[0053] Depend on Figure 2 The carbon sheets of the flaky composite carbon material prepared in Example 2 exhibit a stacked structure, indicating the presence of graphitized carbon, which facilitates rapid electron transfer within the framework. Furthermore, the extremely thin carbon sheets facilitate the creation of short pores, thereby shortening the ion transport distance.

[0054] 3. Charge and discharge curve

[0055] Depend on Figure 3 It can be seen that the specific capacities of the flaky composite carbon materials SCCM5, SCCM6 and SCCM7 prepared in Examples 1-3 as electrode materials for zinc ion hybrid capacitors are 82.1, 125.3 and 80.1 mAh / g, respectively, indicating that the carbon materials obtained in the present invention have a higher specific capacity.

[0056] Comparative Example 1

[0057] The difference from Example 2 is that the activator is different, specifically potassium hydroxide.

[0058] The results show that although the obtained composite material has a large specific surface area, it requires subsequent acid washing treatment, which is costly and cumbersome.

[0059] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for preparing a composite carbon material, characterized in that: The method comprises the following steps: mixing a carbon source, an activating agent and a template, and subjecting the mixture to a carbonization reaction to obtain a composite carbon material; The carbon sources are rice husk carbon and coal tar pitch; The activator is potassium carbonate; The template agents are potassium chloride and nano magnesium oxide.

2. The preparation method according to claim 1, characterized in that The mass ratio of the rice husk carbon to the coal tar pitch is 1:(0.9-1.1).

3. The preparation method according to claim 1 or 2, characterized in that The mass ratio of the activator to the carbon source is (2.5-3.5):

1.

4. The preparation method according to any one of claims 1 to 3, characterized in that The mass ratio of the potassium chloride to the nano-magnesium oxide is 1:(0.9-1.1).

5. The preparation method according to any one of claims 1 to 4, characterized in that The mass ratio of the template to the carbon source is (5.9-6.1):

1.

6. The preparation method according to any one of claims 1 to 5, characterized in that The carbonization reaction is carried out under an argon atmosphere; It consists of two stages: Stage 1: temperature 290-310°C, time 55-65 minutes; The second stage: temperature is 850-860℃, time is 55-65min.

7. The preparation method according to claim 6, characterized in that The heating rate is 4-6°C / min.

8. The preparation method according to any one of claims 1 to 7, characterized in that The method further includes post-processing: crushing the reaction product, adding 1-3 mol / L acid solution, stirring for 11-13 hours, then washing with 75-85°C distilled water until neutral, drying at 100-120°C for 11-13 hours, grinding, and sieving to obtain a flaky composite carbon material.

9. The composite carbon material obtained by the preparation method according to any one of claims 1 to 8.

10. A zinc ion hybrid capacitor, comprising an electrode material; the electrode material is the composite carbon material according to claim 9.

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