Disclosure of Invention
In view of the above, the present invention provides a hollow spherical electrode material, and a preparation method and an application thereof. The hollow spherical electrode material prepared by the preparation method provided by the invention has a higher specific surface area and a larger internal space, and further, the energy density and the cycling stability of the super capacitor can be improved.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a hollow spherical electrode material, which comprises the following steps:
mixing a glucose solution with ammonia water to obtain a mixed solution;
carrying out hydrothermal reaction on the mixed solution to obtain a carbon sphere template;
mixing soluble divalent manganese salt, soluble divalent cobalt salt, lanthanum nitrate and a solvent to obtain a mixed solution;
and mixing the carbon sphere template and the mixed solution, and then sequentially carrying out ultrasonic treatment, standing, solid-liquid separation, drying, grinding and annealing to obtain the hollow spherical electrode material.
Preferably, the temperature of the hydrothermal reaction is 160-190 ℃ and the time is 4-24 h.
Preferably, the dosage ratio of the soluble divalent manganese salt, the soluble divalent cobalt salt, the lanthanum nitrate and the solvent is 5-10 mmol: 5-10 mmol: 10-20 mmol: 20-40 mL.
Preferably, the mass ratio of the soluble divalent cobalt salt, the soluble divalent manganese salt and the lanthanum nitrate is 1: 1: 2.
preferably, the molar ratio of the carbon sphere template to the metal ions in the mixed solution is 1: 2.
preferably, the annealing temperature is 600-900 ℃, and the time is 2-4 h.
Preferably, the heating rate of heating to the annealing temperature is 1-3 ℃/min.
Preferably, the cooling rate of the annealing is 1-3 ℃/min.
The invention also provides a hollow spherical electrode material prepared by the preparation method of the technical scheme, wherein the hollow spherical electrode material is La2CoMnO6Hollow spherical structures formed by nano particles.
The invention also provides application of the hollow spherical electrode material in the technical scheme in the field of supercapacitors.
The invention provides a preparation method of a hollow spherical electrode material, which comprises the following steps: mixing a glucose solution with ammonia water to obtain a mixed solution; carrying out hydrothermal reaction on the mixed solution to obtain a carbon sphere template; mixing soluble divalent manganese salt, soluble divalent cobalt salt, lanthanum nitrate and a solvent to obtain a mixed solution; and mixing the carbon sphere template and the mixed solution, and then sequentially carrying out ultrasonic treatment, standing, solid-liquid separation, drying, grinding and annealing to obtain the hollow spherical electrode material. The hollow spherical electrode material prepared by the method has a higher specific surface area and a larger internal space, has better surface permeability and stability compared with electrode materials prepared by other methods, is beneficial to full contact of an active material and electrolyte, and is convenient for rapid transfer of electrons and ions, so that the circulation stability and the energy density of the super capacitor are improved, and the electrochemical performance is improved. The data of the examples show that La is present at current densities of 1,2,5,8 and 10A/g, respectively2CoMnO6The specific capacitance of the hollow spherical electrode material is 376, 303, 227, 191 and 178F/g respectively, which is much higher than that of La prepared by the comparative example2CoMnO6(94, 73, 49, 36 and 28F/g).
Detailed Description
The invention provides a preparation method of a hollow spherical electrode material, which comprises the following steps:
mixing a glucose solution with ammonia water to obtain a mixed solution;
carrying out hydrothermal reaction on the mixed solution to obtain a carbon sphere template;
mixing soluble divalent manganese salt, soluble divalent cobalt salt, lanthanum nitrate and a solvent to obtain a mixed solution;
and mixing the carbon sphere template and the mixed solution, and then sequentially carrying out ultrasonic treatment, standing, solid-liquid separation, drying, grinding and annealing to obtain the hollow spherical electrode material.
The glucose solution and ammonia water are mixed to obtain a mixed solution. In the invention, the pH value of the mixed solution is preferably 10-14, and more preferably 11.
In the invention, the solvent of the glucose solution is preferably water, and the dosage ratio of the glucose to the solvent in the glucose solution is preferably 40-80 mmol: 80-100 mL.
After the mixed solution is obtained, the mixed solution is subjected to hydrothermal reaction to obtain the carbon sphere template.
In the invention, the temperature of the hydrothermal reaction is preferably 160-190 ℃, more preferably 170-180 ℃, and the time is preferably 4-24 hours, more preferably 6-8 hours. In the present invention, the rate of temperature increase to the temperature of the hydrothermal reaction is preferably 10 ℃/min.
After the hydrothermal reaction is finished, the obtained hydrothermal reaction product is preferably naturally cooled to room temperature, and then is centrifuged and dried to obtain the carbon sphere template. In the invention, the rotation speed of the centrifugation is preferably 6000-7500 r/min, and the time is preferably 30-60 min. In the invention, the drying temperature is preferably 60-80 ℃, and the drying time is preferably 8-12 h.
In the invention, the particle size of the carbon sphere template is preferably 700 nm-1 μm, and the carbon sphere template has good morphology uniformity, uniform particle size and no agglomeration phenomenon.
The method mixes soluble divalent manganese salt, soluble divalent cobalt salt, lanthanum nitrate and solvent to obtain mixed solution.
In the invention, the dosage ratio of the soluble divalent manganese salt, the soluble divalent cobalt salt, the lanthanum nitrate and the solvent is preferably 5-10 mmol: 5-10 mmol: 10-20 mmol: 20-40 mL. In the present invention, the soluble divalent manganese salt is preferably manganese nitrate or manganese chloride, the soluble divalent cobalt salt is preferably cobalt nitrate, cobalt chloride, cobalt acetate or cobalt sulfate, and the solvent is preferably absolute ethanol.
In the present invention, the mass ratio of the soluble divalent cobalt salt, the soluble divalent manganese salt, and the lanthanum nitrate is preferably 1: 1: 2.
after the carbon sphere template and the mixed liquid are obtained, the hollow spherical electrode material is obtained by mixing the carbon sphere template and the mixed liquid, and then sequentially carrying out ultrasonic treatment, standing, solid-liquid separation, drying, grinding and annealing.
In the present invention, the molar ratio of the carbon sphere template to the metal ions in the mixed solution is preferably 1: 2.
in the invention, the time of the ultrasonic treatment is preferably 0.5-1 h.
In the invention, the standing time is preferably 24-120 h, and more preferably 24-72 h.
In the invention, the solid-liquid separation is preferably centrifugal, the rotating speed of the centrifugation is preferably 6000-7000 r/min, and the time is preferably 30-60 min.
In the invention, the drying temperature is preferably 60-80 ℃, and the drying time is preferably 8-12 h, and more preferably 10 h.
The method of polishing in the present invention is not particularly limited, and polishing methods known to those skilled in the art may be used. The degree of grinding is not particularly limited in the present invention, and may be selected from those known to those skilled in the art.
In the invention, the annealing temperature is preferably 600-900 ℃, more preferably 700 ℃, and the time is preferably 2-4 h, more preferably 3 h.
In the present invention, the rate of temperature rise to the annealing temperature is preferably 1 to 3 ℃/min.
In the invention, the cooling rate of the annealing is preferably 1-3 ℃/min.
The invention also provides a hollow spherical electrode material prepared by the preparation method of the technical scheme, wherein the hollow spherical electrode material is La2CoMnO6Hollow spherical structures formed by nano particles.
In the present invention, the La2CoMnO6The particle size of the nanoparticles is preferably 30-50 nm, the diameter range of the hollow spherical structure is preferably 1-3 μm, preferably 1.5 μm, and the wall thickness is preferably 8-12 nm, and more preferably 10 nm.
The invention also provides application of the hollow spherical electrode material in the technical scheme in the field of supercapacitors.
In order to further illustrate the present invention, the following will describe the hollow spherical electrode material provided by the present invention, its preparation method and application in detail with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
7.2064g of glucose is dissolved in 80mL of deionized water to form a uniform solution, the pH value of the solution is adjusted to 11 by ammonia water, then the mixed solution is transferred to a 100mL reaction kettle, the mixed solution is moved to a thermostat to be heated to 180 ℃, the heating rate is 10 ℃/min, the mixed solution is kept for 6h, the mixed solution is naturally cooled to room temperature after the reaction is finished, a carbon sphere template is obtained by centrifugation, the mixed solution is washed for several times by distilled water and absolute ethyl alcohol, and finally the mixed solution is dried for 12h at the constant temperature of 60 ℃.
Fig. 1 is a scanning electron microscope image of a carbon sphere template prepared in example 1, and it can be seen from fig. 1 that the carbon sphere template is mainly composed of spherical particles having a diameter of several hundred nanometers.
Example 2
(1) 8.6582g of La (NO)3)3·6H2O, 2.9105g of Co (NO)3)2·6H2O and 2.5101g of Mn (NO)3)2·4H2O was dissolved in 40mL of absolute ethanol (stirred at room temperature)1h)。
(2) Adding 1.2g of the carbon sphere template prepared in the example 1 into the mixed solution prepared in the step (1), continuously performing ultrasonic treatment for 1 hour to uniformly disperse the carbon spheres, and standing at room temperature for 72 hours; after several times of centrifugation, washing with deionized water for three times and absolute ethyl alcohol for three times, and finally transferring the mixture into a 60 ℃ forced air drying oven for drying for 10 hours to obtain black precursor powder.
(3) Putting the precursor powder prepared in the step (2) into a muffle furnace to anneal at 700 ℃ for 3h (the heating and cooling rates are both 1 ℃/min) to obtain La2CoMnO6Hollow spherical electrode materials, i.e. La2CoMnO6The hollow ball.
FIG. 2 is La prepared in example 22CoMnO6Scanning Electron microscopy of hollow spherical electrode materials, La, as can be seen in FIG. 22CoMnO6The diameter of the hollow spherical electrode material is about 1 mu m, and La is arranged on the spherical material2CoMnO6The mesoporous formed by the nano particles can provide sufficient channels for diffusing electrolyte ions for an electrode material, and is favorable for the transmission of electrolyte.
FIG. 3 is La prepared in example 22CoMnO6FIG. 3 shows a transmission electron microscope image of the hollow spherical electrode material, which is La2CoMnO6The nano particles (with darker colors) form a hollow sphere structure, and the hollow structure is favorable for storage and utilization of electrolyte and can effectively improve the ion utilization rate. CO generation due to sintering of carbon spheres during annealing2And a large amount of mesoporous structures are generated on the hollow spheres, so that the electrolyte can be effectively diffused into the electrode material, and the specific surface area can be increased, so that the number of reactive active sites is increased, and the electrochemical performance is obviously improved.
FIG. 6 is La prepared in example 22CoMnO6The cyclic voltammogram of the hollow spherical electrode material at different scanning speeds can be seen from FIG. 6, and the synthesized La2CoMnO6The potential window of the hollow spherical electrode material is-0.1-1.0V, and the potential window is wider.
FIG. 7 is a preparation of example 2La of (2)2CoMnO6The cycling stability of the hollow sphere electrode material is shown in FIG. 7, in 1M Na2SO4When the solution is used as an electrolyte, 2500 cyclic voltammetry charge-discharge tests are carried out at a current of 3A/g, and after 2500 cycles, the specific capacity is kept at 98 percent of the initial capacity, so that excellent cyclic stability is shown.
FIG. 9 is La prepared in example 22CoMnO6Specific capacitance of the hollow spherical electrode material at different current densities, as can be seen from FIG. 9, La was found at current densities of 1,2,5,8 and 10A/g, respectively2CoMnO6The specific capacitance of the hollow sphere electrode material is 376, 303, 227, 191 and 178F/g respectively.
Comparative example
First, 8.6582g of La (NO) was taken in terms of molar ratio3)3·6H2O, 2.9105g of Co (NO)3)2·6H2O and 2.5101g of Mn (NO)3)2·4H2O, dissolved in 30mL of deionized water. Next, 7.6848g of citric acid was added to the nitrate mixed solution, and stirring was continued at 80 ℃ with a small amount of ethylene glycol added after heating at 80 ℃ for 1 hour, and stirring was continued at 90 ℃ until a wet gel was formed. The wet gel was then placed in an electrovacuum oven at 80 ℃ and thoroughly dried to form a precursor. Finally sintering the obtained product for 3 hours at 700 ℃ in a muffle furnace (the heating rate is 1 ℃/min) to obtain La2CoMnO6I.e. La2CoMnO6A material prepared by a sol-gel method.
FIG. 4 is La prepared by comparative example2CoMnO6FIG. 4 shows a scanning electron micrograph of La2CoMnO6Mainly composed of irregular particles with a diameter of tens of nanometers.
FIG. 5 is La prepared in example 22CoMnO6Hollow spherical electrode material and La prepared in comparative example2CoMnO6FIG. 5 shows the X-ray diffraction pattern of La obtained in example 22CoMnO6Hollow spherical electrode material and La prepared in comparative example2CoMnO6Has a diffraction peak corresponding to ICSD #98240, and La prepared in comparative example2CoMnO6The intensity of the diffraction peak is relatively weak, which indicates that the crystallinity is poor, and the diffraction peaks of the two materials respectively correspond to the standard cards, which indicates that no other miscellaneous items are generated.
FIG. 8 is La prepared in example 22CoMnO6Hollow spherical electrode material and La prepared in comparative example2CoMnO6As can be seen from FIG. 9, the charge/discharge curve at a current density of 1A/g shows that La is present at the same current density2CoMnO6The hollow spherical electrode material has longer charge-discharge time and better electrochemical performance.
FIG. 10 is La prepared in example 22CoMnO6Hollow spherical electrode material and La prepared in comparative example2CoMnO6The specific capacitance and the current density. As can be seen from FIG. 9, La was observed at current densities of 1,2,5,8 and 10A/g, respectively2CoMnO6The specific capacitance of the hollow spherical electrode material is 376, 303, 227, 191 and 178F/g respectively, which is much higher than that of La prepared by the comparative example2CoMnO6(94, 73, 49, 36 and 28F/g).
Example 3
(1) 4.2847g of La (NO)3)3·6H2O, 1.4635g of Co (NO)3)2·6H2O and 1.2603g of Mn (NO)3)2·4H2O was dissolved in 20mL of absolute ethanol (stirred at room temperature for 0.5 h).
(2) Adding 0.8g of the carbon sphere template prepared in the example 1 into the mixed solution prepared in the step (1), continuously performing ultrasonic treatment for 0.5h to uniformly disperse the carbon spheres, and standing at room temperature for 24 h; after several times of centrifugation, washing with deionized water for three times and absolute ethyl alcohol for three times, and finally transferring the mixture into a 60 ℃ forced air drying oven for drying for 10 hours to obtain black precursor powder.
(3) Putting the precursor powder prepared in the step (2) into a muffle furnace to anneal at 700 ℃ for 3h (the heating and cooling rates are both 1 ℃/min) to obtain La2CoMnO6Hollow spherical electrode material.
FIG. 11 is La prepared in example 32CoMnO6Scanning electron microscopy of hollow spherical electrode material, as can be seen in figure 11,La2CoMnO6the diameter of the hollow spherical electrode material is about 1.5 mu m, the hollow spherical electrode material has good dispersibility, and the surface of the hollow spherical electrode material still has obvious La2CoMnO6The perovskite particles are overlapped to form a pore channel.
Example 4
(1) 5.5701g of La (NO)3)3·6H2O, 1.9308g of Co (NO)3)2·6H2O and 1.6503g of Mn (NO)3)2·4H2O was dissolved in 20mL of absolute ethanol (stirred at room temperature for 0.5 h).
(2) Adding 1.24g of the carbon sphere template prepared in the example 1 into the mixed solution prepared in the step (1), continuously performing ultrasonic treatment for 0.5h to uniformly disperse the carbon spheres, and standing at room temperature for 24 h; after several times of centrifugation, washing with deionized water for three times and absolute ethyl alcohol for three times, and finally transferring the mixture into a 60 ℃ forced air drying oven for drying for 10 hours to obtain black precursor powder.
(3) Putting the precursor powder prepared in the step (2) into a muffle furnace to anneal at 900 ℃ for 3h (the heating and cooling rates are both 3 ℃/min) to obtain La2CoMnO6Hollow spherical electrode material.
FIG. 12 is La prepared in example 42CoMnO6Scanning electron micrograph of the hollow spherical electrode material, and as can be seen from observation of FIG. 12, La2CoMnO6The diameter of the hollow spherical electrode material is about 3 μm, and the diameter of the material is increased due to the increase of the annealing temperature and the annealing speed, so that the grain size is increased, and the surface of the material has obvious La2CoMnO6The perovskite particles are overlapped to form a pore channel.
Example 5
Same as example 3, except that the annealing temperature was 600 ℃ to obtain para-La2CoMnO6Characterization of the hollow sphere electrode material resulted in a scanning electron micrograph similar to that of FIG. 11.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention.