Electrode material for biomass-based supercapacitor and preparation method of electrode material

Abstract

The invention relates to the technical field of capacitors, in particular to an electrode material for a biomass-based supercapacitor and a preparation method of the electrode material. The electrode material comprises biomass-based carbon and multi-element metal sulfide distributed on the surface and the inner hole wall of the biomass-based carbon, and the multi-element metal sulfide is Zn-Mo-CdS. The electrode material prepared by the invention has an extremely high specific capacitance value, meanwhile, the capacitance retention rate is relatively high, and good cycle stability is shown.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitors, and in particular to an electrode material for a biomass-based supercapacitor and a preparation method thereof. Background Art

[0002] In recent years, carbon materials have become the most important supercapacitor electrode materials due to their advantages such as good chemical stability, high specific surface area, excellent conductivity, diverse forms and wide operating temperature range.

[0003] When carbon materials are used as electrode materials for supercapacitors, since they only exhibit double-layer capacitance properties, they are often required to have a large specific surface area in order to achieve high specific capacity. Porous carbon has abundant pores and a large specific surface area, making it very suitable as an electrode material for supercapacitors. However, even so, the specific capacity of carbon materials is still too low, and the electrochemical performance needs to be improved. Therefore, in order to improve the capacitance performance of carbon materials, in addition to optimizing the morphology, structural modification is also required. Heteroatom doping and compounding with pseudocapacitive materials are two commonly used methods. Summary of the invention

[0004] Purpose of the invention: In view of the above technical problems, the present invention proposes an electrode material for a biomass-based supercapacitor and a preparation method thereof.

[0005] The technical solutions adopted are as follows:

[0006] An electrode material for a biomass-based supercapacitor, comprising nitrogen-doped biomass-based carbon;

[0007] And multi-metal sulfides distributed on the surface and internal pore walls of the biomass-based carbon.

[0008] Furthermore, the multi-metal sulfide is Zn-Mo-CdS.

[0009] Furthermore, the preparation method of the nitrogen-doped biomass-based carbon is as follows:

[0010] The biomass raw materials and organic amines are mixed in a weight ratio of 10-30:1, heated to 600-800°C in an inert atmosphere, carbonized for 1-4 hours, then acid washed, washed with water and dried.

[0011] Furthermore, the biomass raw material is any one or more combinations of corn cobs, walnut shells, peanut shells, coconut shells, rice straw, and wheat straw.

[0012] Furthermore, the organic amine includes aliphatic amine and alcohol amine, and the weight ratio of the aliphatic amine to the alcohol amine is 1-5:1-5.

[0013] Furthermore, the fatty amine is any one or more combinations of diethylamine, triethylamine and ethylenediamine.

[0014] Furthermore, the alcoholamine is any one or more combinations of monoethanolamine, diethanolamine and triethanolamine.

[0015] Furthermore, the heating rate is 1-10°C / min.

[0016] The present invention also provides a method for preparing an electrode material for a biomass-based supercapacitor:

[0017] Dissolve zinc acetate, ammonium molybdate and cadmium acetate in water to obtain a solution, add nitrogen-doped biomass-based carbon, disperse with ultrasonic oscillation, add dropwise sodium sulfide solution under stirring, continue stirring for more than 12 hours, heat to 150-170°C for hydrothermal reaction for more than 12 hours, cool to room temperature, collect the product, wash and dry.

[0018] Furthermore, it is characterized in that the molar ratio of zinc acetate, ammonium molybdate and cadmium acetate is 1:1:5-10.

[0019] Beneficial effects of the present invention:

[0020] The present invention provides an electrode material for a biomass-based supercapacitor, which uses a composition of aliphatic amine and alcohol amine as a nitrogen source, introduces nitrogen elements into biomass-based carbon, changes the charge density and surface physical and chemical properties of the carbon material, provides more active sites, and enables the electrode material to have excellent electrochemical properties. Moreover, through comparative tests, it can be seen that the nitrogen-doping effect of the triethylamine and triethanolamine composition is better than that of urea. It may be that triethylamine and triethanolamine are not only used as nitrogen sources, but also can react with acidic impurities and oxygen-containing functional groups in biomass raw materials to generate gas or water-soluble compounds and reduce the oxygen content of the carbon material, thereby playing a role in regulating the chemical properties of the biomass-based carbon and improving the electrochemical properties.

[0021] Composite biomass-based carbon and metal sulfide is a good choice to improve the electrochemical performance of electrode materials, which can achieve complementary advantages of the two. On the one hand, biomass-based carbon provides a certain double-layer capacitance and improves the conductivity of metal sulfide, and the porous structure provides sufficient space for the adsorption, desorption and rapid transfer of electrolyte ions, so that the electrolyte can quickly penetrate into the electrode material to reach more electrochemically active sites, thereby improving the utilization rate of metal sulfide. On the other hand, the structure of metal sulfide is protected from being destroyed, and the cycle stability is improved. Metal sulfide provides high energy density, thereby obtaining an electrode material with excellent performance. Compared with single metal sulfide, the multi-metal sulfide used in the present invention can better meet the energy storage needs of supercapacitors, utilize the synergistic effect between metal ions, provide more active sites for the reaction, and have more superior redox performance and higher conductivity.

[0022] After testing, it is found that the electrode material prepared by the present invention has an extremely high specific capacitance value, and at the same time, a high capacitance retention rate, showing good cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the SEM image of the electrode material prepared in Example 1. DETAILED DESCRIPTION

[0024] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. The techniques not mentioned in the present invention are all referenced to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0025] Embodiment 1:

[0026] A method for preparing an electrode material for a biomass-based supercapacitor:

[0027] The coconut shell was dried and crushed into 80 mesh powder and dried to a moisture content of ≤5% as a biomass raw material. Corn cob powder, triethylamine and triethanolamine in a weight ratio of 20:0.5:0.5 were mixed, and the temperature was raised to 800°C at a rate of 5°C / min under an argon atmosphere. After carbonization for 2 hours, it was washed with 0.1 mol / L hydrochloric acid to remove impurities, and then washed with deionized water to neutrality. Finally, it was dried at 80°C for 10 hours to obtain nitrogen-doped biomass-based carbon. 1.83g zinc acetate (10mmol), 1.96g ammonium molybdate (10mmol) and 18.44g cadmium acetate (80mmol) were dissolved in 500ml deionized water to obtain a solution, and then 100g nitrogen-doped biomass-based carbon was added, ultrasonic oscillation dispersion was performed for 30 minutes, and 55ml was added dropwise under stirring conditions. 2 mol / L sodium sulfide solution, continue stirring for 15 h, heat to 160 °C for hydrothermal reaction for 24 h, cool to room temperature, collect the product, wash with deionized water and anhydrous ethanol several times, and dry at 80 °C for 10 h.

[0028] Embodiment 2:

[0029] A method for preparing an electrode material for a biomass-based supercapacitor:

[0030] Walnut shells were dried and crushed into 80 mesh powder and dried to a moisture content of ≤5% as biomass raw materials. Corn cob powder, triethylamine and triethanolamine in a weight ratio of 30:0.5:0.5 were mixed, heated to 800°C at a rate of 10°C / min under an argon atmosphere, and carbonized for 4 hours, then washed with 0.1 mol / L hydrochloric acid to remove impurities, and then washed with deionized water to neutrality, and finally dried at 80°C for 10 hours to obtain nitrogen-doped biomass-based carbon. 1.83g zinc acetate (10mmol), 1.96g ammonium molybdate (10mmol) and 18.44g cadmium acetate (80mmol) were dissolved in 500ml deionized water to obtain a solution, and then 100g nitrogen-doped biomass-based carbon was added, ultrasonically dispersed for 30min, and 55ml was added dropwise under stirring. 2 mol / L sodium sulfide solution, continue stirring for 15 h, heat to 170 °C for hydrothermal reaction for 24 h, cool to room temperature, collect the product, wash with deionized water and anhydrous ethanol several times, and dry at 80 °C for 10 h.

[0031] Embodiment 3:

[0032] A method for preparing an electrode material for a biomass-based supercapacitor:

[0033] The corn cob was dried in the sun and crushed into 80 mesh powder and dried to a moisture content of ≤5% as a biomass raw material. The corn cob powder, triethylamine and triethanolamine in a weight ratio of 25:0.5:0.5 were mixed, and the temperature was raised to 700°C at a rate of 1°C / min under an argon atmosphere. After being carbonized for 2 hours, it was washed with 0.1 mol / L hydrochloric acid to remove impurities, and then washed with deionized water to neutrality. Finally, it was dried at 80°C for 10 hours to obtain nitrogen-doped biomass-based carbon. 1.83g zinc acetate (10mmol), 1.96g ammonium molybdate (10mmol) and 18.44g cadmium acetate (80mmol) were dissolved in 500ml deionized water to obtain a solution, and then 100g nitrogen-doped biomass-based carbon was added, ultrasonic oscillation dispersion was performed for 30 minutes, and 55ml was added dropwise under stirring conditions. 2 mol / L sodium sulfide solution, continue stirring for 15 h, heat to 150 °C for hydrothermal reaction for 24 h, cool to room temperature, collect the product, wash with deionized water and anhydrous ethanol several times, and dry at 80 °C for 10 h.

[0034] Comparative Example 1:

[0035] The process is substantially the same as in Example 1, except that triethylamine and triethanolamine are replaced by equal weights of urea.

[0036] Comparative Example 2:

[0037] The same as Example 1, except that triethylamine was replaced by an equal weight of triethanolamine.

[0038] Comparative Example 3:

[0039] The same as Example 1, except that triethanolamine was replaced by an equal weight of triethylamine.

[0040] Comparative Example 4:

[0041] The method is substantially the same as Example 1, except that only 100 mmol of zinc acetate is added, and ammonium molybdate and cadmium acetate are not added.

[0042] Comparative Example 5:

[0043] The method is substantially the same as Example 1, except that only 100 mmol of ammonium molybdate is added, and zinc acetate and cadmium acetate are not added.

[0044] Comparative Example 6:

[0045] The method is substantially the same as Example 1, except that only 100 mmol of cadmium acetate is added, and zinc acetate and ammonium molybdate are not added.

[0046] Performance Test:

[0047] The electrochemical performance of the electrode materials prepared in Examples 1-3 and Comparative Examples 1-6 of the present invention was tested using a three-electrode system;

[0048] The working electrode is made of electrode material, acetylene black and polytetrafluoroethylene with a mass ratio of 8:1:1, which are dissolved in ethanol and then ground and mixed, and coated on a 1cm×1cm nickel foam, and then dried and compacted. A saturated calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, and 1mol / L H2SO4 is used as an electrolyte to form a three-electrode system. The specific capacitance of the three-electrode system at a current density of 1A / g and the capacitance retention rate after 10,000 cycles are tested using a CH1760D electrochemical workstation. The test results are shown in Table 1:

[0049] Table 1:

[0050]

[0051] As can be seen from Table 1 above, the electrode material prepared by the present invention has an extremely high specific capacitance value, and at the same time, the capacitance retention rate is high, showing good cycle stability;

[0052] By comparing the data of Example 1 with that of Comparative Example 1, it can be seen that the nitrogen doping effect of the triethylamine and triethanolamine composition of the present invention is better than that of urea;

[0053] By comparing the data of Example 1 with Comparative Examples 2 and 3, it can be seen that the nitrogen doping effect of the triethylamine and triethanolamine combination is better than that of single triethylamine or triethanolamine, so that the combination improves the electrochemical performance of the electrode material more significantly;

[0054] By comparing the data of Example 1 with Comparative Examples 4, 5, and 6, it can be seen that the introduction of multi-metal sulfides improves the electrochemical performance of the electrode material better than that of a single metal sulfide.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biomass-based supercapacitor electrode material, characterized in that: including nitrogen-doped biomass-based carbon; And multi-metal sulfides distributed on the surface and internal pore walls of the biomass-based carbon.

2. The biomass-based supercapacitor electrode material according to claim 1, characterized in that: The multi-metal sulfide is Zn-Mo-CdS.

3. The biomass-based supercapacitor electrode material according to claim 2, characterized in that: The preparation method of the nitrogen-doped biomass-based carbon is as follows: The biomass raw materials and organic amines are mixed in a weight ratio of 10-30:1, heated to 600-800°C in an inert atmosphere, carbonized for 1-4 hours, then acid washed, washed with water and dried.

4. The biomass-based supercapacitor electrode material according to claim 3, characterized in that: The biomass raw material is any one or more combinations of corn cobs, walnut shells, peanut shells, coconut shells, rice straws, and wheat straws.

5. The biomass-based supercapacitor electrode material according to claim 3, characterized in that: The organic amine includes aliphatic amine and alcohol amine, and the weight ratio of the aliphatic amine to the alcohol amine is 1-5:1-5.

6. The biomass-based supercapacitor electrode material according to claim 5, characterized in that: The fatty amine is any one or more combinations of diethylamine, triethylamine and ethylenediamine.

7. The biomass-based supercapacitor electrode material according to claim 5, characterized in that: The alcohol amine is any one or more combinations of monoethanolamine, diethanolamine and triethanolamine.

8. The biomass-based supercapacitor electrode material according to claim 5, characterized in that: The heating rate is 1-10℃ / min.

9. A method for preparing a biomass-based supercapacitor electrode material according to any one of claims 2 to 8, characterized in that: Dissolve zinc acetate, ammonium molybdate and cadmium acetate in water to obtain a solution, add nitrogen-doped biomass-based carbon, disperse with ultrasonic oscillation, add dropwise sodium sulfide solution under stirring, continue stirring for more than 12 hours, heat to 150-170°C for hydrothermal reaction for more than 12 hours, cool to room temperature, collect the product, wash and dry.

10. The method for preparing a biomass-based supercapacitor electrode material according to claim 9, characterized in that: The molar ratio of zinc acetate, ammonium molybdate and cadmium acetate is 1:1:5-10.

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