Multi-metal-atom co-doped nano carbon material as well as preparation method and application thereof

Abstract

The invention relates to a multi-metal-atom co-doped nano carbon material as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) dissolving a triblock copolymer and sodium oleate in water to obtain a template agent, mixing the template agent with a biomass-based carbon source, and carrying out a hydrothermal reaction to obtain a first precursor; (2) sequentially adding polyvinylpyrrolidone, a nickel source, a cobalt source, a manganese source and the first precursor into ethylene glycol to obtain a mixed solution; mixing and heating the mixed solution to obtain a second precursor; and (3) performing high-temperature activation and carbonization on the second precursor to obtain the multi-metal-atom co-doped nano carbon material. The multi-metal atom co-doped nano carbon material disclosed by the invention has good electrochemical performance. The preparation method disclosed by the invention is relatively simple to operate, relatively short in preparation period, controllable in synthesis condition, high in practicability and capable of realizing large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon materials, and in particular to a multi-metal atom co-doped nano-carbon material and a preparation method and application thereof. Background Art

[0002] Supercapacitors are a new type of energy storage element that uses active substances to adsorb electrolyte ions onto the surface of electrode materials without contacting each other, thereby forming a double layer and redox reaction to store energy. It has the advantages of high power density, fast charge and discharge speed, and long-range cycle stability. It can meet the growing energy demand and alleviate the pressure of environmental pollution. The microstructure, particle size, porosity and physical and chemical properties of the electrode material have a huge impact on electrochemical capacitors.

[0003] Hollow carbon is used as an electrode material for supercapacitors because of its good stability, special hollow structure, high specific surface area, stable physical and chemical properties, and good capacitance performance. However, its low conductivity and low energy density severely limit its commercial application. Therefore, the use of metal to modify carbon materials to increase their conductivity has better electrochemical properties than traditional porous carbon, which has attracted widespread attention from researchers.

[0004] Existing studies have shown that doping metal elements into carbon materials can improve the structure and physical and chemical properties of biochar, increase the specific surface area and pore volume, enhance hydrophobicity, and have more defective structures. This can greatly improve its specific capacitance, which is mainly manifested in the following aspects: First, the charge storage capacity of metal oxides mainly depends on their reversible redox reactions. Therefore, metal oxides have a larger specific capacitance than carbon material electrodes. Therefore, doping metal atoms in carbon materials can introduce Faraday redox reactions, bring additional pseudocapacitance, and effectively improve its specific capacitance to make up for the shortcomings of carbon materials; secondly, the successful doping of metal atoms such as Mn introduces an appropriate amount of defects, which improves the electronic conductivity of the material, and metals such as Mn are easier to achieve Mn 2+ / Mn 4+ The reversible transformation is beneficial to Li + The reversible deintercalation improves the discharge specific capacity.

[0005] Biomass is low-cost, easy to obtain, and has a simple preparation process, making it an excellent carbon source. Hollow carbon materials have a larger specific surface area than ordinary carbon materials, which is conducive to the storage and rapid migration of electrolyte ions. The preparation methods of hollow carbon generally use KOH activation method or template method, but the above methods are all prepared through multi-step operations, with many process variables and great difficulty in commercialization. Therefore, providing a bio-based high-capacitance nanocarbon material with a relatively simple preparation method, a short preparation cycle, controllable synthesis conditions, strong practicality and large-scale production is a technical problem that needs to be solved in this field. Summary of the invention

[0006] To solve the above technical problems, the object of the present invention is to provide a multi-metal atom co-doped nano-carbon material, a preparation method thereof and an application. The multi-metal atom co-doped nano-carbon material of the present invention successfully dopes metal atoms, increases the pseudocapacitance of the nano-carbon material prepared into a capacitor, and further improves the specific capacitance of the nano-carbon material, so that the nano-carbon material has good electrochemical performance. The preparation method of the present invention is relatively simple in operation, short in preparation period, controllable in synthesis conditions, strong in practicability and can be produced on a large scale.

[0007] The technical solution for the present invention to solve the above technical problems is as follows:

[0008] The first object of the present invention is to provide a preparation method of a multi-metal atom co-doped nano-carbon material, comprising the following steps:

[0009] (1) Dissolve a triblock copolymer and sodium oleate in water to obtain a template agent, mix the template agent with a biomass-based carbon source and then carry out a hydrothermal reaction to obtain a first precursor;

[0010] (2) Add polyvinylpyrrolidone, a nickel source, a cobalt source, a manganese source, and the first precursor to ethylene glycol in sequence to obtain a mixed solution; heat the mixed solution to obtain a second precursor;

[0011] (3) Carry out high-temperature activation carbonization on the second precursor to obtain a multi-metal atom co-doped nano-carbon material.

[0012] The beneficial effects of the present invention are: (1) The present invention uses a biomass-based carbon source as a carbon precursor, a triblock copolymer and sodium oleate as a double soft template, and drugs containing metal atoms as a nickel source, a cobalt source, and a manganese source, and adopts a hydrothermal carbonization method to prepare a metal atom co-doped nano-carbon material. The successful doping of metal atoms increases the pseudocapacitance of the material prepared into a capacitor, and further improves the specific capacitance of the material, so that the material has good electrochemical performance.

[0013] (2) The preparation method of the present invention has a short preparation period, controllable synthesis conditions, and strong practicability, and is a directly feasible method for improving electrochemical performance.

[0014] On the basis of the above technical solutions, the present invention can also be improved as follows.

[0015] Further, after the hydrothermal reaction in step (1), centrifugation and drying are also required; the rotation speed of the centrifugation is 8000-10000 r / min; the drying temperature is 55-65 °C.

[0016] Further, after the mixed heating in step (2), centrifugation and drying are required; the rotation speed of the centrifugation is 8000 - 10000 r / min; the temperature of the drying is 55 - 65 °C.

[0017] Further, the specific process of the high-temperature activation carbonization in step (3) is as follows: In a tubular furnace, it is heated to 540 - 560 °C at a heating rate of 1 - 9.5 °C / min, held for 0.9 - 5 h, then heated to 840 - 860 °C at a heating rate of 1 - 5.5 °C / min, held for 0.9 - 1.1 h, and then naturally cooled to room temperature.

[0018] Further, the biomass-based carbon source includes at least one of glucose, ribose, and fructose; the nickel source includes at least one of nickel acetate and nickel nitrate; the cobalt source includes at least one of cobalt nitrate and cobalt acetate; the manganese source includes at least one of manganese nitrate and manganese acetate; the triblock copolymer is polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol (P123);

[0019] The relative molecular weight of the polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol is 5000 - 6000.

[0020] The beneficial effects of adopting the above further scheme are as follows: The raw materials of the preparation method disclosed in the present invention are common and easy to obtain, without using strong alkalis, strong acids, or toxic reagents. By changing the carbon source material and adjusting the reaction time, the morphology of the nano-carbon material can be controlled. Electrochemical performance tests are carried out on the nitrogen and sulfur co-doped multi-metal atom co-doped nano-carbon material, and a supercapacitor electrode material with high specific capacitance, low resistance, and good cycle stability can be obtained.

[0021] Further, in step (1), the mass ratio of the triblock copolymer, sodium oleate, and the biomass-based carbon source is 43.5 - 70:36.5 - 80:3000 - 9000.

[0022] Further, in step (2), the dosage ratio of the first precursor, polyvinylpyrrolidone (PVP), ethylene glycol (EG), the nickel source, the cobalt source, and the manganese source is 0.5 g - 0.9 g:1 g:200 mL:0.069 - 0.21 g:0.071 - 0.21 g:0.29 g - 0.87 g.

[0023] Further, the specific conditions of the hydrothermal reaction in step (1) are as follows: It is heated in a hydrothermal reaction kettle at a heating rate of 4.5 - 5.5 °C / min; the reaction temperature is 155 - 165 °C; the reaction time is 7 - 9 h; after the reaction, it is naturally cooled to 80 °C;

[0024] The specific process of the mixed heating in step (2) is as follows: heat up in a hydrothermal reactor at a rate of 1 °C / min to 5.5 °C / min; the reaction temperature is 115 °C to 125 °C; the reaction time is 11 to 13 h; after the reaction, heat up at a rate of 4.5 to 5.5 °C / min; the reaction temperature is 155 to 165 °C; the reaction time is 1.5 to 2.5 h; after the reaction, naturally cool down to 80 °C.

[0025] Further, before the hydrothermal reaction in step (1), an amino acid is further added, and the amino acid includes at least one of cysteine and methionine.

[0026] The beneficial effects of adopting the above further scheme are as follows: the raw materials of the preparation method disclosed in the present invention are common and easily available, without using strong alkalis, strong acids, and toxic reagents. By changing the carbon source material and adjusting the reaction time, the morphology of the nanocarbon material can be regulated.

[0027] Further, the mass ratio of the biomass-based carbon source to the amino acid in step (1) is 9:0.1 to 0.2.

[0028] The second object of the present invention is to provide a multi-metal atom co-doped nanocarbon material.

[0029] The beneficial effects of the present invention are as follows: (1) The multi-metal atom co-doped nanocarbon material prepared by the present invention is monodisperse, with uniformly regular open-shaped particles. The hollow structure enables the nanomaterial to have a high specific surface area and a short lithium-ion transmission path, thus having a high specific capacitance. Moreover, it can effectively release the stress caused by the expansion of the material due to charge and discharge, improving the cycle stability. The mass fraction of the doped metal is 1.67% to 6.32%. The successful doping of metal atoms increases the pseudocapacitance of the material prepared into a capacitor and further improves the specific capacitance of the material, making the material have good electrochemical performance.

[0030] (2) The multi-metal atom co-doped nanocarbon material prepared by the present invention has a special structure. The hollow structure can effectively release the stress caused by the expansion of the material due to charge and discharge, enhancing its cycle stability. Secondly, the successful doping of metal atoms such as Mn introduces appropriate defects into the carbon material, improving the electronic conductivity of the material, and Mn metal is more likely to achieve the reversible conversion of Mn 2+ / Mn 4+ which is beneficial to the reversible deintercalation and intercalation of Li + and thus improves the discharge specific capacity.

[0031] (3) The multi-metal atom co-doped nano-carbon material uses a carbon material as the matrix and has the characteristics of an electrode material for a typical double-layer supercapacitor. The metal atoms can undergo redox reactions with the alkaline electrolyte through these sites, thereby exhibiting the characteristics of pseudocapacitance. Therefore, it can be used as a composite capacitive electrode material. Its advantage over a single electrode material for a double-layer supercapacitor lies in its excellent stability, and its advantage over a single electrode material for pseudocapacitance lies in its large capacitance.

[0032] Furthermore, the nano-carbon material is particles with an open hollow structure having a diameter distribution of 300 - 800 nm, an opening diameter of 130 - 760 nm, and a carbon shell thickness of 20 - 200 nm.

[0033] Furthermore, the nano-carbon material is hollow particles with an open structure, such as structures like hollow carbon bowls, hollow carbon bottles, and single-layer carbon bowls.

[0034] The third object of the present invention is to provide an application of a multi-metal atom co-doped nano-carbon material, using the said nano-carbon material as the positive electrode and / or negative electrode in a supercapacitor.

[0035] Furthermore, using the said nano-carbon material as the positive electrode and / or negative electrode in a supercapacitor is specifically as follows: using the multi-metal atom co-doped nano-carbon material as the active material, acetylene black as the conductive agent, and polytetrafluoroethylene microemulsion as the binder, grinding and mixing evenly. Then evenly coating it on nickel foam and drying to obtain the dried material, and assembling the dried material into a supercapacitor in a potassium hydroxide electrolyte. Description of the Drawings

[0036] Figure 1 It is the field emission scanning electron microscope image and transmission electron microscope image of the multi-metal atom co-doped nano-carbon material of Example 1 of the present invention; where (a) is the field emission scanning electron microscope image; (b) is the transmission electron microscope image;

[0037] Figure 2 It is the field emission scanning electron microscope image of the multi-metal atom co-doped nano-carbon material of Example 2 of the present invention;

[0038] Figure 3 It is the field emission scanning electron microscope image of the multi-metal atom co-doped nano-carbon material of Example 3 of the present invention;

[0039] Figure 4 It is the cyclic voltammetry curve and constant current charge / discharge curve of the multi-metal atom co-doped nano-carbon material of Example 1 of the present invention as a supercapacitor electrode material; where (a) is the cyclic voltammetry curve; (b) is the constant current charge / discharge curve;

[0040] Figure 5 Cyclic stability diagram and electrochemical impedance spectrum of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 1 of the present invention; where (a) is the cyclic stability diagram; (b) is the electrochemical impedance spectrum;

[0041] Figure 6 Infrared spectrum of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 1 of the present invention;

[0042] Figure 7 X-ray photoelectron spectrum of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 1 of the present invention; where (a) is the full spectrum; (b) is the C1s spectrum; (c) is the Mn 2p spectrum; (d) is the Ni 2p spectrum; (e) is the Co 2p spectrum;

[0043] Figure 8 XRD pattern of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 1 of the present invention;

[0044] Figure 9 N 2 adsorption-desorption isotherm diagram and pore size distribution diagram of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 1 of the present invention; where (a) is the N 2 adsorption-desorption isotherm diagram; (b) is the pore size distribution diagram;

[0045] Figure 10 Cyclic voltammetry curve and galvanostatic charge / discharge curve of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 2 of the present invention; where (a) is the cyclic voltammetry curve; (b) is the galvanostatic charge / discharge curve;

[0046] Figure 11 Cyclic stability diagram and electrochemical impedance diagram of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 2 of the present invention; where (a) is the cyclic stability diagram; (b) is the electrochemical impedance diagram;

[0047] Figure 12 Infrared spectrum of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 2 of the present invention;

[0048] Figure 13 N 2 adsorption-desorption isotherm diagram and pore size distribution diagram of the multi-metal atom co-doped nano-carbon material as a supercapacitor electrode material in Example 2 of the present invention; where (a) is the N 2 adsorption-desorption isotherm diagram; (b) is the pore size distribution diagram;

[0049] Figure 14 It is the X-ray photoelectron full spectrum of the multi-metal atom co-doped nano-carbon material in Example 2 of the present invention as a supercapacitor electrode material;

[0050] Figure 15 It is the X-ray photoelectron spectrum of the multi-metal atom co-doped nano-carbon material in Example 2 of the present invention as a supercapacitor electrode material; where (a) is the C1s spectrum; (b) is the N1s spectrum; (c) is the S2P spectrum; (d) is the Mn 2p spectrum; (e) is the Ni 2p spectrum; (f) is the Co 2p spectrum;

[0051] Figure 16 It is the cyclic voltammetry curve and galvanostatic charge / discharge curve of the multi-metal atom co-doped nano-carbon material in Example 3 of the present invention as a supercapacitor electrode material; where (a) is the cyclic voltammetry curve; (b) is the galvanostatic charge / discharge curve;

[0052] Figure 17 It is the cycle stability diagram and electrochemical impedance diagram of the multi-metal atom co-doped nano-carbon material in Example 3 of the present invention as a supercapacitor electrode material; where (a) is the cycle stability diagram; (b) is the electrochemical impedance diagram;

[0053] Figure 18 It is the infrared spectrum of the multi-metal atom co-doped nano-carbon material in Example 3 of the present invention as a supercapacitor electrode material;

[0054] Figure 19 It is the N 2 adsorption-desorption isotherm diagram and pore size distribution diagram of the multi-metal atom co-doped nano-carbon material in Example 3 of the present invention as a supercapacitor electrode material; where (a) is the N 2 adsorption-desorption isotherm diagram; (b) is the pore size distribution diagram;

[0055] Figure 20 It is the X-ray photoelectron full spectrum of the multi-metal atom co-doped nano-carbon material in Example 3 of the present invention as a supercapacitor electrode material;

[0056] Figure 21 It is the X-ray photoelectron spectrum of the multi-metal atom co-doped nano-carbon material in Example 3 of the present invention as a supercapacitor electrode material; where (a) is the C1s spectrum; (b) is the N1s spectrum; (c) is the S2P spectrum; (d) is the Mn 2p spectrum; (e) is the Ni 2p spectrum; (f) is the Co 2p spectrum. Detailed implementation manners

[0057] The principles and features of the present invention will be described below. The examples cited are only used to explain the present invention and are not intended to limit the scope of the present invention. For those not specifying specific techniques or conditions in the examples, the techniques or conditions described in the literature in this field or according to the product specifications are followed. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be purchased through regular channels.

[0058] Example 1: Preparation of multi-metal atom co-doped nano-carbon material I

[0059] (1) Weigh 36.5 mg of sodium oleate and 43.5 mg of P123 and add them to 20 mL of deionized water, stir for two hours to obtain a template agent, then add 40 mL of deionized water solution containing 3 g of ribose to the template agent, and continue to stir for 30 min to obtain a mixed solution. Pour the mixed solution into a 500 ml autoclave for hydrothermal reaction: heat at a rate of 5 °C / min, pressurize and heat at 160 °C for 8 h, then take out the prepared nano-carbon material, naturally cool to 80 °C, centrifuge and wash in turn, the centrifugation rate is 8000 r / min, and then put it in an oven at 60 °C for drying to obtain the first precursor;

[0060] (2) Dissolve 1 g of PVP (purchased from Aladdin) in 200 mL of EG (purchased from Sinopharm Chemical Reagent), heat and stir, add 0.39 mmol of nickel acetate, 0.39 mmol of cobalt nitrate and 1.62 mmol of manganese nitrate during the stirring process, then add 900 mg of the first precursor, ultrasonically treat for 15 min and mix them evenly. Subsequently, transfer it to a 500 mL autoclave, heat at 120 °C for 12 h, then raise the temperature of the autoclave to 160 °C and heat for 2 h, and continuously stir at a speed of 500 r / min during this period. Wash the product three times with water and once with ethanol, and then keep it in an oven at 60 °C for drying to obtain the second precursor;

[0061] (3) Heat the second precursor in a nitrogen atmosphere tubular furnace at a heating rate of 1 °C / min to 550 °C, pre-sinter at 550 °C for 4 h, heat at a heating rate of 1 °C / min to 850 °C, keep this temperature and calcine for 1 h, and then naturally cool to room temperature to obtain the final product of multi-metal atom co-doped nano-carbon material.

[0062] Example 2: Preparation of multi-metal atom co-doped nano-carbon material II

[0063] (1) Weigh 200.75 mg of sodium oleate and 239.25 mg of P123, add them to 110 mL of deionized water, stir at room temperature for 2 hours to obtain a template agent. Then add a 220 mL aqueous solution containing 9 g of glucose to the template agent and mix evenly. Next, add 0.1 g of cysteine and continue to stir for 0.5 hours to obtain a mixed solution. Pour the mixed solution into a 500 mL hydrothermal reaction kettle for hydrothermal reaction: heat up at a rate of 5 °C / min, react at 160 °C for 8 hours, and after the reaction is completed, cool the reaction kettle to room temperature. Centrifuge the cooled nano-carbon material solution, set the centrifuge speed to 10,000 r / min for 10 min, wash it 3 times by centrifugation with deionized water, and then wash it 1 time by centrifugation with ethanol, and dry it overnight to obtain the first precursor;

[0064] (2) First, dissolve 1 g of PVP (purchased from Aladdin) in 200 ml of EG (purchased from Sinopharm Chemical Reagent). Stir and heat on a magnetic stirrer, and sequentially add 1.17 mmol of nickel nitrate, 1.17 mmol of cobalt nitrate, 4.86 mmol of manganese acetate, and 0.5 g of the first precursor to obtain a mixed solution. Put the mixed solution into an ultrasonic machine for 15 min to make it evenly mixed. Then pour it into a 500 ml reaction kettle, evenly heat up to 120 °C and keep the temperature for reaction for 12 h, and then continue to heat up to 160 °C and keep the temperature for reaction for 2 h. Set the stirring rod to 5000 r / min throughout the process and turn on the forward and reverse rotation of the stirring rod. After the reaction is completed, centrifuge the product, wash it with water, set the centrifuge speed to 10,000 r / min for 10 min, wash it 3 times by centrifugation with deionized water, and wash it 1 time by centrifugation with ethanol, and then dry it overnight to obtain the uncalcined second precursor;

[0065] (3) Place the second precursor in a tubular furnace, and uniformly heat the tubular furnace to 550 °C at a rate of 1 °C / min under a nitrogen atmosphere, keep the temperature for sintering for 4 h, then uniformly heat it to 850 °C at a rate of 5 °C / min and maintain this temperature, keep the temperature for sintering for 1 h, and then cool it to room temperature in a nitrogen atmosphere to obtain the final product, a multi-metal atom co-doped nano-carbon material.

[0066] Example 3: Preparation of multi-metal atom co-doped nano-carbon material III

[0067] (1) Weigh 200.75 mg of sodium oleate and 239.25 mg of P123, add 110 mL of deionized water, and stir at room temperature for 2 hours to obtain a template agent. Then add 220 mL of an aqueous solution containing 9 g of ribose to the template agent and mix well. Next, add 0.1 g of cysteine and continue to stir for 0.5 hours to obtain a mixed solution. Pour the mixed solution into a 500 mL hydrothermal reactor for hydrothermal reaction: heat at a rate of 5 °C / min and react at 160 °C for 8 hours. After the reaction is completed, cool the reactor to room temperature, take out the prepared nano-carbon material solution, and centrifuge it. Set the centrifuge speed to 10000 r / min for 10 min, wash it 3 times by centrifugation with deionized water and 1 time by centrifugation with ethanol, and dry it overnight to obtain the first precursor;

[0068] (2) First, dissolve 1 g of PVP (purchased from Aladdin) in 200 ml of EG (purchased from Sinopharm Chemical Reagent), stir and heat on a magnetic stirrer, and sequentially add 1.17 mmol of nickel nitrate, 1.17 mmol of cobalt nitrate, 4.86 mmol of manganese acetate, and 0.5 g of the first precursor to obtain a mixed solution. Put the mixed solution into an ultrasonic machine for 15 min to make the mixed solution homogeneous. Then pour the mixed solution into a 500 ml reactor, uniformly heat up to 120 °C and hold the reaction for 12 h, and then continue to heat up to 160 °C and hold the reaction for 2 h. Set the stirring rod to 5000 r / min throughout the process and turn on the positive and negative rotation of the stirring rod. After the reaction is completed, centrifuge the product, wash it with water. The centrifuge speed is 10000 r / min for 10 min, wash it 3 times by centrifugation with deionized water and 1 time by centrifugation with ethanol, and then dry it overnight to obtain the second precursor;

[0069] (3) Place the second precursor in a tubular furnace, and uniformly heat the tubular furnace to 550 °C at a rate of 1 °C / min under a nitrogen atmosphere, hold the sintering for 4 h, then uniformly heat it to 850 °C at a rate of 5 °C / min and maintain this temperature. After holding the sintering for 1 h, cool it to room temperature in a nitrogen atmosphere to obtain the final product, a multi-metal atom co-doped nano-carbon material.

[0070] Comparative Example 1: Preparation of multi-metal atom co-doped nano-carbon materials

[0071] This comparative example is compared with Example 1. The only difference is that sodium oleate is replaced by sodium laurate, and the rest of the steps and raw materials are the same as those in Example 1.

[0072] Comparative Example 2: Preparation of multi-metal atom co-doped nano-carbon materials

[0073] This comparative example is compared with Example 1. The only difference is that sodium oleate is replaced by sodium dodecyl sulfate, and the rest of the steps and raw materials are the same as those in Example 1.

[0074] Comparative Example 3: Preparation of multi-metal atom co-doped nano-carbon materials

[0075] This comparative example is different from Example 2 only in that sodium oleate is replaced by sodium laurate, and the remaining steps and raw materials are the same as those in Example 2.

[0076] Comparative Example 4: Preparation of Nano-carbon Material Co-doped with Multiple Metal Atoms

[0077] This comparative example is different from Example 2 only in that sodium oleate is replaced by sodium dodecyl sulfate, and the remaining steps and raw materials are the same as those in Example 2.

[0078] Comparative Example 5: Preparation of Nano-carbon Material Co-doped with Multiple Metal Atoms

[0079] This comparative example is different from Example 2 only in that the raw materials in step (3) are different, and the remaining steps and raw materials are the same as those in Example 2. Step (3) is specifically as follows:

[0080] (3) Mix the second precursor, potassium hydrogen carbonate, and ammonium oxalate in a mass ratio of 1:2:2, place them in a tubular furnace, and uniformly heat the tubular furnace to 550 °C at a rate of 1 °C / min under a nitrogen atmosphere, keep the temperature for sintering for 4 h, then uniformly heat it to 850 °C at a rate of 5 °C / min and maintain this temperature, keep the temperature for sintering for 1 h and then cool it to room temperature in a nitrogen atmosphere to obtain the final product, the nano-carbon material co-doped with multiple metal atoms.

[0081] Test Example

[0082] 1. Microscopic Morphology Characterization

[0083] The morphological characteristics of the nano-carbon materials co-doped with multiple metal atoms prepared in Examples 1 to 3 were observed using a field emission scanning electron microscope (GeminiSEM 300; Carl Zeiss AG, Germany), and the results are as Figure 1 (a), Figure 2 , Figure 3 shown; the nano-carbon material co-doped with multiple metal atoms prepared in Example 1 was observed using a transmission electron microscope (JEM-2100, JEOL Ltd., Japan), and the results are as Figure 1 (b) shown.

[0084] From Figures 1 to 3 it can be obtained that:

[0085] (1) From Figure 1 it can be seen that the nano-carbon material co-doped with multiple metal atoms in Example 1 has a hollow carbon bottle structure. The diameter of the hollow carbon bottle is about 550 nm, and it is a monodisperse open spherical particle. The bottleneck structure of the hollow carbon bottle is complete, the surface is relatively rough, and the opening diameter is about 150 nm;

[0086] (2) From Figure 2 ,3 It can be seen that the appearance of the multi-metal atom co-doped nanocarbon materials of Example 2 and Example 3 is a bowl-shaped structure with one end concave inward, with a single structure and uniform size, a diameter of 300nm-400nm, and a shell thickness of 20-30nm. The bowl-shaped carbon material has a large specific surface area and rich pore structure.

[0087] 2. Electrochemical performance and surface morphology detection

[0088] The multi-metal atom co-doped nanocarbon materials of Examples 1 to 3 were used as supercapacitor electrode materials to detect their cyclic voltammetry curves and constant current charge / discharge curves (GCD), cycle stability diagrams and electrochemical impedance diagrams, infrared spectra, X-ray photoelectron spectroscopy, and XRD. A symmetric electrode system was used for testing. The specific detection method is as follows:

[0089] (1) Preparation of electrode materials: The multi-metal atom co-doped nanocarbon materials of Examples 1 to 3 were respectively ground with acetylene black and polyvinylidene fluoride in a mass ratio of 8:1:1 in an agate mortar and mixed evenly, and then N-methyl-2-pyrrolidone (NMP) solvent was added dropwise and ground continuously until the mixture was evenly mixed. The slurry was then applied to nickel foam and dried in a vacuum oven at 50°C. The carbon material loading density of the electrode was quantitatively determined by subtraction to ensure that it was within 1 mg / cm 2 The dried electrode sheets were cut into suitable sizes, the distance between the two electrodes was fixed to 15 mm, and a symmetrical electrode test system was assembled and immersed in 6M KOH electrolyte overnight.

[0090] (2) Electrochemical performance testing: Cyclic voltammetry curves, constant current charge / discharge curves, cycle stability, and electrochemical impedance spectroscopy were performed on the electrode materials prepared in Examples 1 to 3 using an electrochemical workstation;

[0091] (3) Surface morphology detection: The electrode materials prepared in step (1) of Examples 1 to 3 were detected using an infrared spectrometer (Nicolet 6700 Fourier transform infrared spectrometer; Thermo Nicolet Corporation, USA), an X-ray photoelectron spectrometer (ESCALAB XI+; Thermo Fisher Scientific, USA), and an X-ray diffractometer (D8ADVANCE; Bruker, Germany). The results are as follows: Figures 4 to 21 .

[0092] Depend on Figures 4 to 21 We can get:

[0093] (1) Figure 4Cyclic voltammograms and galvanostatic charge / discharge curves (GCD) of the multi-metal atom co-doped nano-carbon material of Example 1 as a supercapacitor electrode material. The cyclic voltammograms show a quasi-rectangular shape at scan rates of 10 mV / s, 50 mV / s, 100 mV / s, 200 mV / s, 500 mV / s, and 1000 mV / s, indicating that the material has good electric double-layer capacitance characteristics. An obvious hump appears at the window position of 0.6 - 0.8 V, which is due to the pseudocapacitance increased by the doping of metal elements. The galvanostatic charge / discharge curves show a typical triangular shape, and it can be seen from the figure that the material has good Coulomb efficiency, indicating that the material has good electrochemical properties. The specific capacitance of the multi-metal atom co-doped hollow carbon bottle is 205.1 F / g at 0.5 A / g, and when the current density is 1 A / g, the specific capacitance is 144.2 F / g. Figure 5 Cyclic stability diagram and electrochemical impedance diagram of the electrode prepared under the above conditions.

[0094] (2) Figure 6 Infrared spectrum of the multi-metal atom co-doped nano-carbon material of Example 1 as a supercapacitor electrode material, for the results of analyzing the surface functional groups of the material. Figure 7 X-ray photoelectron spectroscopy of this material, showing that Mn exists in the form of Mn 2+ and Mn 4+ , proving the existence of Ni 2+ , and also indicating that Co exists in the form of Co 2+ and Co 3+ . Figure 8 Analyze the crystal form of the sample by XRD, corresponding to the results of Figure 7 , Figure 9 which indicates that the material contains a hierarchical pore structure of micropores - mesopores.

[0095] (3) Figure 10 Cyclic voltammograms and galvanostatic charge / discharge curves (GCD) of the multi-metal atom co-doped nano-carbon material of Example 2 as a supercapacitor electrode material. At scan rates of 10 mV / s, 50 mV / s, 100 mV / s, 200 mV / s, 500 mV / s, and 1000 mV / s, it shows a quasi-rectangular shape, indicating that the material has good electric double-layer capacitance characteristics. An obvious hump appears at the window position of 0.5 - 0.7 V, which is due to the pseudocapacitance increased by the doping of metal elements. The galvanostatic charge / discharge curves show that at current densities of 1 A / g, 2 A / g, 5 A / g, 10 A / g, and 20 A / g, the GCD curves show a typical triangular shape, and the capacitance at a current density of 1 A / g is 207.6 F / g, and the specific energy is 7.21 Wh / kg. Figure 11 Cyclic stability diagram and electrochemical impedance diagram of the electrode prepared under the above conditions.

[0096] (4) Figure 12 Infrared spectrum of the multi-metal atom co-doped nano-carbon material of Example 3 as a supercapacitor electrode material, the result for analyzing the surface functional groups of the material Figure 14 、 15 X-ray photoelectron spectroscopy of the material Figure 12 Analyze the crystal form of the sample by XRD Figure 13 It shows that the material contains a hierarchical pore structure of micropores-mesopores

[0097] (5) Figure 16 Cyclic voltammetry curve and galvanostatic charge / discharge curve (GCD) of the multi-metal atom co-doped nano-carbon material of Example 3 as a supercapacitor electrode material. It presents a quasi-rectangle at scan rates of 10 mV / s, 50 mV / s, 100 mV / s, 200 mV / s, 500 mV / s, and 1000 mV / s, indicating that the material has good electric double layer capacitance characteristics. The current densities in the charge / discharge curve are 1 A / g, 2 A / g, 5 A / g, 10 A / g, and 20 A / g, and the GCD curve presents a typical triangle. The capacitance at a current density of 1 A / g is 194.4 F / g, and the specific energy is 6.75 Wh / kg

[0098] (6) Figure 17 Cyclic stability diagram of the nitrogen / sulfur co-doped multi-metal atom co-doped hollow carbon half bowl as a supercapacitor electrode material Figure 18 Infrared spectrum of the material prepared under the above conditions, the result of analyzing the surface light energy groups of the material Figure 19 It shows that the material contains a hierarchical pore structure of micropores-mesopores Figure 20 、 21 X-ray diffraction pattern of the material prepared under the above conditions, showing that the binding form of N element is pyridinic N (N-6) and pyrrolic N (N-5) nitrogen functional groups. The binding form of S is C=S and C-SC bonds, and Mn exists in the form of Mn 2+ and Mn 4+ exists in the form of Ni 2+ exists in the form of Co 2+ and Co 3+ exists in the form of

[0099] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention

Claims

1. A method for preparing a multi-metal atom co-doped nanocarbon material, characterized in that: The preparation method comprises the following steps: (1) dissolving the triblock copolymer and sodium oleate in water to obtain a template, mixing the template with a biomass-based carbon source, and performing a hydrothermal reaction to obtain a first precursor; (2) adding polyvinyl pyrrolidone, a nickel source, a cobalt source, a manganese source, and the first precursor to ethylene glycol in sequence to obtain a mixed solution; mixing and heating the mixed solution to obtain a second precursor; (3) The second precursor is activated and carbonized at high temperature to obtain a nano-carbon material co-doped with multiple metal atoms.

2. The method for preparing a multi-metal atom co-doped nanocarbon material according to claim 1, characterized in that: The biomass-based carbon source includes at least one of glucose, ribose, and fructose; the nickel source includes at least one of nickel acetate and nickel nitrate; the cobalt source includes at least one of cobalt nitrate and cobalt acetate; the manganese source includes at least one of manganese nitrate and manganese acetate; the triblock copolymer is polyethylene glycol-embedded polypropylene glycol-embedded polyethylene glycol; The relative molecular weight of the polyethylene glycol-polypropylene glycol-polyethylene glycol is 5000-6000.

3. The method for preparing a multi-metal atom co-doped nanocarbon material according to claim 1, characterized in that: The mass ratio of the triblock copolymer, the sodium oleate and the biomass-based carbon source in step (1) is 43.5-70: 36.5-80: 3000-9000.

4. The method for preparing a multi-metal atom co-doped nanocarbon material according to claim 1, characterized in that: In step (2), the usage ratio of the first precursor, the polyvinyl pyrrolidone, the ethylene glycol, the nickel source, the cobalt source, and the manganese source is 0.5g-0.9g: 1g: 200mL: 0.069-0.21g: 0.071-0.21g: 0.29g-0.87g.

5. The method for preparing a multi-metal atom co-doped nanocarbon material according to claim 4, characterized in that: The specific conditions of the hydrothermal reaction in step (1) are as follows: heating in a hydrothermal reactor at 4.5-5.5°C / min; reaction temperature of 155-165°C; reaction time of 7-9h; and cooling naturally to below 80°C after the reaction. The mixed heating in step (2) is specifically as follows: heating in a hydrothermal reactor at 1°C / min to 5.5°C / min; the reaction temperature is 115°C to 125°C; the reaction time is 11 to 13 hours; after the reaction is completed, heating at 4.5 to 5.5°C / min; the reaction temperature is 155 to 165°C; the reaction time is 1.5 to 2.5 hours; after the reaction is completed, the temperature is naturally lowered to below 80°C.

6. The method for preparing a multi-metal atom co-doped nanocarbon material according to any one of claims 1 to 5, characterized in that: In step (1), amino acids are added before the hydrothermal reaction, wherein the amino acids include at least one of cysteine ​​and methionine.

7. The method for preparing a multi-metal atom co-doped nanocarbon material according to claim 6, characterized in that: The mass ratio of the biomass-based carbon source to the amino acid in step (1) is 9:0.1-0.

2.

8. A multi-metal atom co-doped nanocarbon material, characterized in that: The multi-metal atom co-doped nanocarbon material is prepared according to the preparation method according to any one of claims 1 to 7.

9. The multi-metal atom co-doped nanocarbon material according to claim 8, characterized in that: The nano carbon material is a particle with a diameter distribution of 300-800nm, an opening diameter of 130-760nm, a carbon shell thickness of 20-200nm and an opening hollow structure.

10. Application of a multi-metal atom co-doped nanocarbon material, characterized in that: The nanocarbon material according to any one of claims 8 to 9 is used as a positive electrode and / or a negative electrode in a supercapacitor.

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