Phosphorus-doped orange peel-based carbon material for supercapacitor and preparation method of phosphorus-doped orange peel-based carbon material
By performing phosphorus doping and high-temperature activation treatment in orange peel-based carbon materials, porous carbon materials with high specific capacitance and stability were prepared, which solved the problems of poor stability and high production costs of existing supercapacitor materials, and achieved green and environmentally friendly and efficient energy storage materials.
Patent Information
- Application Number
- CN202510035018.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-09
- Publication Date
- 2025-05-27
AI Technical Summary
Existing supercapacitor materials have poor stability during long-term operation, and the activators such as zinc chloride used in the production process have a risk of environmental pollution and are costly.
Porous carbon materials are prepared by using orange peel as a carbon precursor and using two-step process of phosphorus doping and high-temperature activation to improve the specific capacitance and stability of the material, reduce production costs, and reduce environmental harm.
The specific capacitance value of the supercapacitor material reaches 302F/g. After the stability test, the specific capacitance retention rate is still above 96%. The conductivity and surface wetting of the material are significantly improved, reducing production costs and reducing environmental pollution.
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Figure CN120048662A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of electrochemical energy storage of carbon materials, and particularly to a phosphorus-doped orange peel-based carbon material for supercapacitors and a preparation method thereof. Background Art
[0002] Due to the increasingly serious problems such as energy depletion, population growth, and environmental pollution, the concept of green and sustainable development has taken root in people's hearts. How to develop and utilize renewable clean energy and research and develop high-efficiency energy storage devices has become a current research hotspot. Among the emerging energy storage devices, supercapacitors have received extensive attention due to their outstanding advantages such as long cycle life, high power density, wide operating temperature range, and excellent specific capacitance. In recent years, biomass has become one of the preferred carbon precursors for preparing porous carbon materials due to its wide variety, unique porous structure, simple preparation method, and rich heteroatoms. It not only has the potential for large-scale production but also practices the concept of green, environmental, and sustainable development, solving the problem of waste treatment in daily life, agriculture, factories, etc.
[0003] Heteroatom doping is to introduce different types of heteroatoms into the carbon skeleton to replace some carbon atoms, including single-doped porous carbon and co-doped porous carbon. Thanks to their different radii and electronegativities, these heteroatoms can generate various structural defects and adjust the charge distribution to obtain better conductivity. Heteroatoms can introduce more active sites and functional groups. Therefore, introducing heteroatoms can further enhance the physical and chemical properties such as the conductivity and surface wettability of carbon materials, form a synergistic effect, and improve their electrochemical properties. Currently, the most widely studied is nitrogen doping, which has been proven to significantly improve the electrochemical properties of carbon materials. The amorphous nanostructure of nitrogen doping enhances the conductivity and active sites, the nitrogen atoms are embedded in the carbon skeleton, and both the specific capacitance and cycle performance of the material are significantly improved. Similar to nitrogen doping, other heteroatoms can also significantly improve the electrochemical properties of carbon materials. For example, boron is usually doped inside the graphene plane, which can be used to increase the in-plane defects; while sulfur doping can significantly expand the carbon layer spacing. Phosphorus atoms have relatively low electronegativity and high electron-donating ability, and have received increasing attention in recent years. Phosphorus has a high theoretical capacity and can further increase the specific capacitance of the material through reactions with electrolyte ions. On the other hand, phosphorus doping can bring more defects and larger layer spacing, etc., so it can also improve the ion transport rate. Phosphorus doping can improve the surface wettability of carbon materials, which is beneficial to the full infiltration of the electrolyte; the surface functional groups brought by doping have redox activity, thus enhancing the pseudocapacitance reaction; the low electronegativity and large volume of phosphorus can accelerate the electron and ion transport processes.
[0004] To meet the environmental protection concept and reduce production costs, it is very important to select a suitable carbon precursor. Oranges are abundant in southern China, and a large amount of orange peel is produced every day in daily life and food processing. Orange peel is rich in various polysaccharides. According to reports, the sum of cellulose, lignin, and hemicellulose in orange peel accounts for 50% of the total dry mass. However, due to the high cost of homogenizing different components, it is difficult to dispose of. Therefore, using orange peel as a carbon precursor to prepare biochar is a good way to solve the problem of waste orange peel, which can not only reuse resources to achieve the concept of green environmental protection but also provide carbon materials with excellent performance for energy storage. Summary of the Invention
[0005] The purpose of the present invention is to provide a phosphorus-doped orange peel-based carbon material for supercapacitors and its preparation method. Specifically: using waste orange peel as the raw material, through two steps of simple phosphorus doping pretreatment and high-temperature activation, a phosphorus-doped orange peel-based porous carbon material is obtained, which has excellent capacitance performance through electrochemical test experiments. This material can be applied to supercapacitor electrode materials.
[0006] To achieve the above invention purpose, the technical solution adopted by the present invention is as follows:
[0007] A preparation method of a phosphorus-doped orange peel-based porous carbon material, comprising the following steps: using orange peel as the raw material, and obtaining the phosphorus-doped orange peel-based porous carbon material after phosphorus doping and activation.
[0008] Further, using orange peel as the precursor, a phosphorus-containing doping source reagent as the doping source, and an alkaline substance as the activator, the phosphorus-doped orange peel-based porous carbon material is prepared through the steps of hydrothermal doping, high-temperature activation, and drying.
[0009] Further, it includes the following steps:
[0010] (1) Phosphorus doping pretreatment: rinsing the orange peel with deionized water, drying and crushing it to obtain orange peel powder, then mixing it with a phosphorus-containing doping source and a surfactant, adding water, transferring it into a reaction kettle, and placing it in an oven. React at a low temperature to make the orange peel undergo phosphorus doping. Filter and wash the reacted sample with deionized water, and then dry it;
[0011] (2) High-temperature activation treatment: uniformly mixing the phosphorus-doped orange peel with the activator, and performing high-temperature activation carbonization. Immerse the sample after high-temperature activation in hydrochloric acid and ultrasonicate it, then filter and wash it with deionized water until neutral, and dry it in an environment of 60 °C to obtain the phosphorus-doped orange peel-based carbon material.
[0012] Further, in step (1), the drying and crushing is to place the orange peel in an oven, heat it to 50 - 100 °C and dry it for 12 - 24 hours, and then crush the dried orange peel into powder form.
[0013] Further, in step (1), the mass ratio of the orange peel powder, the phosphorus-containing doping source reagent, and the surfactant is 1.0: 1.0 - 6.0: 0.2 - 0.8, the reaction temperature is 150 - 200 °C, and the reaction time is 6 - 18 hours.
[0014] Further, in step (1), the phosphorus-containing doping source reagent is an inorganic phosphate or phosphoric acid; the surfactant is F127.
[0015] Preferably, the inorganic phosphate is selected from one or more of calcium phosphate, ammonium phosphate, sodium dihydrogen phosphate, sodium hydrogen phosphate, and potassium phosphate.
[0016] Preferably, in step (2), the mass ratio of the phosphorus-doped orange peel to the activator is 1.0: 1.0 - 4.0, and the carbonization conditions are as follows: under a nitrogen atmosphere, the furnace temperature is adjusted to 600 - 800 °C, and the carbonization time is preset to 1 - 4 hours; the activator is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate.
[0017] The present invention also includes a phosphorus-doped orange peel-based porous carbon material prepared by the above preparation method, and the specific surface area of the phosphorus-doped orange peel-based porous carbon material is 1000 - 1800 m 2 / g.
[0018] The present invention also provides an application of the above phosphorus-doped orange peel-based porous carbon material as a supercapacitor electrode material.
[0019] Compared with the prior art, the present invention has the following advantages:
[0020] 1) A phosphorus-doped orange peel-based carbon material is designed. Compared with the best embodiment, it shows that under the same conditions, the specific capacitance of the carbon material doped with phosphorus is 2.11 times that of the carbon material sample without this step.
[0021] 2) Compared with the activation technology of similar biomass raw materials, the present invention obtains a carbon material rich in phosphorus-containing functional groups. Moreover, the phosphorus uniformly distributed in the material after phosphorus-doping pretreatment will help the activation of the carbon material at high temperatures, reducing the amount of alkali used, reducing the production cost, improving the utilization rate of alkali, and effectively reducing the harm to the environment;
[0022] 3) The process of the present invention is simple, and orange peel is fully utilized as the initial raw material, which is rich in sources and low in price. It is mainly obtained from food processing and daily consumption. The preparation process is simple and easy to implement, low in cost, safe and non-toxic, and effectively realizes the resource utilization of waste substances;
[0023] 4) The porous carbon material prepared by this method has a large number of pores on its surface as detected by scanning electron microscopy experiments; it has excellent capacitance performance as detected by electrochemical test experiments. When the current density is 0.5 A / g, the specific capacitance value reaches 302 F / g; after 10,000 cycles of stability testing, the retention rate of its specific capacitance is still above 96%, showing excellent stability, thus overcoming the common disadvantages of poor long-term operation stability and low specific capacitance retention rate of carbon materials activated by activators such as zinc chloride used in current commercial supercapacitors. Brief Description of the Drawings
[0024] Figure 1 is the SEM image of the coexistence of multiple morphologies obtained in Example 1 of the present invention;
[0025] Figure 2 is the SEM image of the carbon microsphere morphology obtained in Comparative Example 2 of the present invention;
[0026] Figure 3 is the GCD graph of the carbon material obtained in Example 1 of the present invention;
[0027] Figure 4 is the cyclic test graph of the carbon material obtained in Example 1 of the present invention at a current of 5 A / g;
[0028] Figure 5 is the GCD graph of the carbon material obtained in Comparative Example 1 of the present invention;
[0029] Figure 6 is the GCD graph of the carbon material obtained in Comparative Example 2 of the present invention;
[0030] Figure 7 is the GCD graph of the carbon material obtained in Comparative Example 3 of the present invention;
[0031] Figure 8 is the GCD graph of the carbon material obtained in Comparative Example 4 of the present invention;
[0032] Figure 9 is the GCD graph of the carbon material obtained in Example 2 of the present invention;
[0033] Figure 10 is the GCD graph of the carbon material obtained in Example 3 of the present invention. Detailed Embodiments
[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0035] Example 1:
[0036] A preparation method of a porous carbon material based on orange peel, comprising the following steps:
[0037] First, wash the collected orange peel with deionized water, then dry it at 80 °C, grind the dried orange peel to obtain orange peel powder, then add 5 g of orange peel powder, 5 g of potassium phosphate, and 1 g of F127 (polyoxyethylene-polyoxypropylene block copolymer) into a beaker, add 100 mL of deionized water and stir for 30 minutes, transfer it into a reaction kettle and pre-treat it at 180 °C for 12 hours. After washing the pre-treated sample with deionized water until neutral and drying, obtain a phosphorus-doped pre-treatment precursor of orange peel, named TP-P1. Uniformly mix the pre-treated sample and sodium hydroxide in a ratio of 1:3, place the mixed powder in a tube furnace, under a nitrogen atmosphere, heat up to 700 °C, keep the temperature constant for 2 hours for high-temperature activation, after cooling to room temperature, soak the product in an appropriate amount of 1 M hydrochloric acid solution and ultrasonicate for 30 minutes, then filter and wash with deionized water until neutral, and dry at 60 °C for 24 hours to obtain a phosphorus-doped orange peel-based carbon material, named TP-P1-A13.
[0038] In order to study the morphology and structure of the carbon material in this embodiment, the inventor carried out SEM tests. The test results are as Figure 1 shown. It can be seen that the carbon material in this embodiment has a carbon microsphere structure formed by phosphorus-doped hydrothermal pre-treatment reaction, and after high-temperature activation, the sample has abundant macropores, mesopores and micropores.
[0039] In order to prove the application of the carbon material in this embodiment as a supercapacitor electrode material, the inventor carried out constant current charge and discharge tests. The test results are as Figure 3 and Table 2 shown. It can be seen that when the current density is 0.5 A / g, the specific capacitance value reaches 302 F / g.
[0040] In order to prove that the carbon material in this embodiment has good rate performance, charge and discharge tests were carried out at different current densities. The test results are shown in Table 1. When the current density is 10 A / g, the specific capacitance still reaches 218 F / g, showing good rate performance.
[0041] Table 1 Comparison table of specific capacitance of TP-P1-A13
[0042] Sample Name 0.5 A / g 1 A / g 2 A / g 4 A / g 6 A / g 10 A / g TP-P1-A13 302 F / g 276.4 F / g 264.8 F / g 250.4 F / g 237 F / g 218 F / g
[0043] In order to prove that the carbon material in this embodiment has good capacitance retention rate, in a three-electrode test system, in an aqueous 6 M KOH electrolyte, a constant current charge and discharge test was carried out at a current density of 5 A / g. The test results are as Figure 4As shown, after 10,000 cycles, its specific capacitance retention rate is 96.1%, showing excellent capacitance retention rate.
[0044] To prove the influence of phosphoric acid doping in the first step and the activation effect of alkali in the second step of high-temperature activation on the electrochemical performance in this embodiment, Comparative Example 1 and Comparative Example 2 are provided, where
[0045] Comparative Example 1:
[0046] The collected orange peels were washed with deionized water and dried at 80 °C, then ground to obtain orange peel powder. 5 g of orange peel powder and 1 g of F127 (polyoxyethylene-polyoxypropylene block copolymer) were added to a beaker, 100 mL of deionized water was added and stirred for 30 minutes, then transferred to a reaction kettle and pretreated at 180 °C for 12 hours. After the pretreated sample was washed with deionized water until neutral and dried, an orange peel pretreatment sample without phosphorus doping was obtained, named TP-P0. The pretreated sample and sodium hydroxide were uniformly mixed in a ratio of 1:3, and the mixed powder was placed in a tubular furnace. Under a nitrogen atmosphere, it was heated to 700 °C and kept at a constant temperature for 2 hours for high-temperature activation. After cooling to room temperature, the product was put into an appropriate amount of 1 M hydrochloric acid solution and ultrasonicated for 30 minutes, and then filtered and washed with deionized water until neutral, and dried at 60 °C for 24 hours, named TP-P0-A13. The constant current charge-discharge test results of the carbon material are as Figure 5 and Table 2 show that when the current density is 0.5 A / g, the specific capacitance value reaches 143 F / g.
[0047] Comparative Example 2:
[0048] The collected orange peels were washed with deionized water, then dried and ground at 80 °C to obtain orange peel powder. Then, 5 g of orange peel powder, 5 g of potassium phosphate, and 1 g of F127 (polyoxyethylene-polyoxypropylene block copolymer) were added to a beaker, 100 mL of deionized water was added and stirred for 30 minutes, then transferred to a reaction kettle and pretreated at 180 °C for 12 hours. After the pretreated sample was washed with deionized water until neutral and dried, a phosphorus-doped pretreatment precursor of orange peel was obtained, named TP-P1. The pretreated sample was placed in a tubular furnace. Under a nitrogen atmosphere, it was heated to 700 °C and kept at a constant temperature for 2 hours for high-temperature carbonization. After cooling to room temperature, the product was put into an appropriate amount of 1 M hydrochloric acid solution and ultrasonicated for 30 minutes, and then filtered and washed with deionized water until neutral, and dried at 60 °C for 24 hours, named TP-P1-A0. The constant current charge-discharge test results of the carbon material are as Figure 6 and Table 2 show that when the current density is 0.5 A / g, the specific capacitance value reaches 126 F / g. The SEM of the Comparative Example 2 sample is as Figure 2As shown, it is found that its structure is a carbon microsphere structure rich in surface functional groups, and no pore structure is found, indicating that the increase in specific surface area and the abundant pores come from the high-temperature carbonization after adding sodium hydroxide.
[0049] To illustrate the influence of the dosage of the phosphorus dopant on the specific capacitance when the material of the present invention is used as the electrode material for supercapacitors, the inventors gave Examples 2 and 3 with different dosages of the phosphorus dopant.
[0050] Comparative Example 3:
[0051] The difference between this comparative example and Example 1 is that 5 g of orange peel powder and 5 g of potassium phosphate are added to 100 mL of deionized water for phosphorus doping pretreatment, and the mass ratio of the pretreatment product to sodium hydroxide is 1:3, and other conditions are the same as those in Example 1, named TP-P3-A13. The test results are as Figure 7 shown in Table 2. When the current density is 0.5 A / g, the specific capacitance value reaches 169 F / g.
[0052] Comparative Example 4:
[0053] The difference between this comparative example and Example 1 is that 5 g of orange peel powder and 5 g of sodium hydrogen phosphate are added to 100 mL of deionized water for phosphorus doping pretreatment, and the mass ratio of the pretreatment product to sodium hydroxide is 1:3, and other conditions are the same as those in Example 1, named TP-P6-A13. The test results are as Figure 8 shown in Table 2. When the current density is 0.5 A / g, the specific capacitance value reaches 162 F / g.
[0054] To illustrate the influence of the dosage of the alkali in the second-step high-temperature activation on the mass specific capacitance when the material of the present invention is used as the electrode material for supercapacitors, the inventors gave Examples 4 and 5 with different dosages of the alkali.
[0055] Example 2:
[0056] The difference between this example and Example 1 is that the sample pretreated by phosphorus doping and sodium hydroxide are uniformly mixed in a ratio of 1:2 for high-temperature activation, and other conditions are the same as those in Example 1, named TP-P1-A12. The test results are as Figure 9 shown in Table 2. When the current density is 0.5 A / g, the specific capacitance value reaches 206 F / g.
[0057] Example 3:
[0058] The difference between this example and Example 1 is that the sample pretreated by phosphorus doping and sodium hydroxide are uniformly mixed in a ratio of 1:4 for high-temperature activation, and other conditions are the same as those in Example 1, named TP-P1-A14. The same test results are as Figure 10As shown in Table 2, when the current density is 0.5 A / g, the specific capacitance value reaches 255 F / g.
[0059] The constant current charge-discharge test data of the above-mentioned examples and comparative examples at a current density of 0.5 A / g are shown in Table 2.
[0060] Table 2 Summary Table of Electrochemical Data
[0061] Serial Number Specific Capacitance (F / g) Example 1 302 Comparative Example 1 143 Comparative Example 2 126 Comparative Example 3 169 Comparative Example 4 162 Example 2 206 Example 3 255
[0062] By comparing the above examples with the comparative examples, it can be seen that the present invention effectively improves the electrochemical performance of the material through simple phosphorus doping pretreatment and high-temperature activation. The orange peel carbon material prepared by the present invention has a carbon microsphere structure with rich functional groups and retains a porous structure. The process is simple, reducing the production cost and environmental pollution.
[0063] The above description is a detailed description of the preferred and feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications made under the technical spirit disclosed by the present invention shall fall within the scope of the patent covered by the present invention.
Claims
1. A method for preparing a phosphorus-doped orange peel-based porous carbon material, characterized in that: The following steps are involved: Orange peel is used as a raw material, and the phosphorus-doped orange peel-based porous carbon material is obtained after phosphorus doping and activation.
2. The method for preparing phosphorus-doped orange peel-based porous carbon according to claim 1, characterized in that: The phosphorus-doped orange peel-based porous carbon material is prepared by using orange peel as a precursor, a phosphorus-containing doping source reagent as a doping source, and an alkaline substance as an activator through the steps of hydrothermal doping, high-temperature activation, and drying.
3. The preparation method according to claim 2, characterized in that: The following steps are involved: (1) Phosphorus doping pretreatment: The orange peel is rinsed with deionized water, dried and crushed to obtain orange peel powder, which is then mixed with a phosphorus-containing doping source and a surfactant, and water is added to a reaction kettle and placed in an oven for low-temperature reaction to cause the orange peel to undergo phosphorus doping. The sample after the reaction is filtered and washed with deionized water, and then dried; (2) High-temperature activation treatment: The phosphorus-doped orange peel is uniformly mixed with an activator and subjected to high-temperature activation carbonization. The sample after high-temperature activation is immersed in hydrochloric acid and ultrasonicated, then filtered and washed with deionized water until neutral, and dried at 60°C to obtain the phosphorus-doped orange peel-based carbon material.
4. The preparation method according to claim 3, characterized in that: In step (1), the drying and crushing is performed by placing the orange peel in an oven, heating it to 50-100° C. and drying it for 12-24 hours, and then crushing the dried orange peel into powder.
5. The preparation method according to claim 3, characterized in that: In step (1), the mass ratio of the orange peel powder to the phosphorus-containing doping source reagent and the surfactant is 1.0:1.0-6.0:0.2-0.8, the reaction temperature is 150-200° C., and the reaction time is 6-18 hours.
6. The preparation method according to claim 3, characterized in that: In step (1), the phosphorus-containing doping source reagent is a phosphorus-containing inorganic salt or phosphoric acid; and the surfactant is F127.
7. The preparation method according to claim 6, characterized in that: The phosphorus-containing inorganic salt is selected from one or more of calcium phosphate, ammonium phosphate, sodium dihydrogen phosphate, sodium hydrogen phosphate, and potassium phosphate.
8. The preparation method according to claim 3, characterized in that: In step (2), the mass ratio of the phosphorus-doped orange peel to the activator is 1.0:1.0-4.0, and the carbonization conditions are: in a nitrogen atmosphere, the furnace temperature is adjusted to 600-800° C., and the carbonization time is preset to 1-4 hours; the activator is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate.
9. The phosphorus-doped orange peel-based porous carbon material prepared according to any one of claims 1 to 8, characterized in that: The specific surface area of the phosphorus-doped orange peel-based porous carbon material is 1000-1800 m 2 / g.
10. Use of the phosphorus-doped orange peel-based porous carbon material prepared according to claim 1 as a supercapacitor electrode material.