CN110571061A - Preparation method of graphene @ CoAl-LDH composite electrode material - Google Patents
Preparation method of graphene @ CoAl-LDH composite electrode material Download PDFInfo
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- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
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- H—ELECTRICITY
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- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
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- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
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Abstract
The invention relates to a preparation method of a graphene @ CoAl-LDH composite electrode material, which is characterized in that graphene oxide aerogel is obtained by freeze drying; preparing a mixed solution of the CoAl; carrying out hydrothermal reaction on the graphene aerogel and the CoAl mixed solution, and carrying out freeze drying when the temperature is reduced to room temperature to obtain the graphene @ CoAl-LDH composite electrode material. Compared with the prior art, the preparation method of the graphene @ CoAl-LDH composite electrode material is simple and environment-friendly, has controllable cost, and can be used for research on energy storage of green energy materials.
Description
Technical Field
The invention belongs to the field of chemical energy storage of materials, and particularly relates to a preparation method of a graphene @ CoAl-LDH composite electrode material.
Background
In recent years, with the continuous progress of science and technology, the required energy consumption is more and more. The problems of non-negligible energy exhaustion and environmental pollution are of great concern. Efforts are made to develop new efficient methods for solving this problem with devices having higher memory performance. Super capacitor is extensively studied as next generation energy storage, mainly it has higher power density, fast charge and discharge, small, long cycle life performance. The super capacitor has impressive characteristics, and can be widely applied to renewable energy sources such as hybrid electric vehicles, batteries and solar energy conversion. However, the development of the currently commercially available super capacitor is limited by its lower energy density, and in order to improve this state, an electrode material having a high specific capacitance and an enlarged voltage window to thereby increase the energy density is developed.
The use of organic electrolyte is required for the design of expanding the voltage window, but the prepared non-aqueous electrolyte has low conductivity, high cost and is not environment-friendly. In addition, the other method is to prepare an electrode material with higher energy density, and the electrode material is widely researched and used at present, such as activated carbon, graphene oxide, carbon-oxygen organisms, carbon nanotubes, transition metal oxides and the like. The graphene is a two-dimensional monoatomic layered carbon material, has excellent performances such as large surface area, high conductivity and good mechanical stability, and has a wide application prospect in the super capacitor. Furthermore, by combining the nanometal oxide with graphene, firstly, the conductivity and speed capability of the metal oxide will be significantly improved, and secondly, the graphene on the surface of the metal oxide particles will prevent the accumulation and aggregation of graphene nanoplatelets leading to an increase in the available electrochemical surface area. Therefore, the electrochemical performance of the composite electrode material composed of graphene and nano metal oxide is generally superior to that of the metal oxide alone. In recent years, transition metal layered double hydroxides have become a hot research point for electrode materials of supercapacitors due to the advantages of low cost, high pseudo-capacitance, long cycle life and the like. The surface area of a new electrode material prepared by combining transition metal and graphene oxide reported in the prior art is influenced by the potential stacking phenomenon of the graphene oxide, so that the performance of the electrode material is influenced.
Disclosure of Invention
the invention aims to overcome the defects in the prior art and provide a preparation method of a graphene @ CoAl-LDH composite electrode material. The method is simple to operate and environment-friendly, the obtained graphene @ CoAl-LDH composite electrode material can overcome the defects of poor conductivity, easy agglomeration and the like of the bimetallic oxide in the prior art, and meanwhile, the composite electrode material has good cycling stability and mechanical flexibility.
The purpose of the invention can be realized by the following technical scheme:
A preparation method of a graphene @ CoAl-LDH composite electrode material comprises the steps of obtaining graphene oxide aerogel through freeze drying; preparing a mixed solution of the CoAl; carrying out hydrothermal reaction on the graphene aerogel and a CoAl mixed solution, and carrying out freeze drying when the temperature is reduced to room temperature to obtain the graphene @ CoAl-LDH composite electrode material, wherein the method comprises the following specific steps:
(1) Preparation of graphene oxide aerogel
Preparing graphene oxide by using an improved Hummer method, carrying out ultrasonic treatment on the prepared graphene oxide and deionized water according to different proportions, and then carrying out freeze drying on a graphene oxide aqueous solution to obtain the graphene oxide aerogel.
(2) Preparation of CoAl Mixed solution
The cobalt salt and the deionized water are stirred and mixed according to different proportions, the aluminum salt and the deionized water are stirred and mixed according to different proportions, the cobalt salt solution and the aluminum salt solution are mixed according to different proportions, then, the urea, the ammonium fluoride and the CTAB are added and stirred and mixed, the selectable cobalt salt is cobalt nitrate, cobalt acetate or cobalt chloride, and the aluminum salt is aluminum nitrate, aluminum acetate or aluminum chloride.
(3) Preparation of graphene @ CoAl-LDH composite electrode material
Carrying out hydrothermal reaction on the prepared graphene oxide aerogel and a CoAl mixed solution according to different proportions, replacing the graphene oxide aerogel and the CoAl mixed solution with deionized water when the temperature is close to room temperature, and carrying out freeze drying to obtain the graphene @ CoAl-LDH composite electrode material.
In the invention, in the step (1), the ultrasonic time of the graphene oxide and the deionized water is 1-2h, and the mixing mass ratio of the graphene oxide to the deionized water is 1:2-3: 2.
In the invention, in the step (1), the freeze-drying time of the graphene oxide aqueous solution is 1-8 h.
In the invention, in the step (2), the mixing ratio of the cobalt salt and the deionized water is 2mg:1ml-20mg:1ml, and the stirring time of the cobalt salt and the deionized water is 15-30 min.
In the invention, in the step (2), the mixing ratio of the aluminum salt to the deionized water is 2mg:1ml-10mg:1ml, and the stirring time of the aluminum salt and the deionized water is 15-30 min.
In the invention, in the step (2), the molar ratio of the cobalt salt to the aluminum salt is 5:1-1:1, and the mixing and stirring time of the cobalt salt and the aluminum salt is 15-30 min.
In the invention, in the step (2), the mass ratio of the cobalt salt to the urea is 1:1-1:5, preferably 1:1, the mass ratio of the cobalt salt to the ammonium fluoride is 6:1-15:1, and the mass ratio of the cobalt salt to CTAB is 4:1-1: 1.
in the invention, in the step (3), the hydrothermal reaction temperature of the graphene oxide aerogel and the CoAl mixed solution is 12-24h, and the reaction temperature is 110-140 ℃.
In the invention, in the step (3), the temperature of freeze drying is-2 to-20 ℃, and the time is 12 to 24 hours.
Compared with the prior art, the electrode material prepared by carrying out hydrothermal and freeze drying treatment on the graphene oxide aerogel and the CoAl bimetal well overcomes the defect that the performance of the electrode material is influenced by the stacking of graphene oxide existing in the traditional bimetal and graphene oxide. And through condition screening, the molar mass ratio of the graphene oxide aerogel to the CoAl is 1:4, urea with controllable morphology (the ratio of nickel nitrate to urea is 1:1) is added, meanwhile, N atom doping is carried out by using ammonium fluoride, the morphology is controlled, and different specific gravities of urea and ammonium fluoride can influence the morphology of the prepared electrode material, so that different electrochemical properties are caused. Meanwhile, through experimental investigation, the graphene oxide aerogel and CoAl are selectively treated for 15 hours at 120 ℃ to obtain the mixed electrode material. Due to different hydrothermal temperatures and times, the reaction degree, the morphology and the dispersion degree of particles of the material are different, and the conductivity of the electrode material is further influenced.
The graphene @ CoAl-LDH composite electrode material obtained by the method disclosed by the invention fully utilizes the synergistic effect between graphene and a bimetallic oxide, overcomes the defects of poor cycle performance of a single metal oxide and low energy density of a single carbon material, and is good in cycle stability, excellent in charge and discharge performance, strong in shape controllability, higher in specific capacitance and one of ideal energy materials.
drawings
FIG. 1 is a scanning electron micrograph of an electrode material prepared in example 1;
FIG. 2 is a scanning electron micrograph of the electrode material prepared in example 2;
FIG. 3 is an x-ray diffraction pattern of the electrode material prepared in example 2;
FIG. 4 is a graph of the constant current charge and discharge characteristics of the electrode material prepared in example 2;
fig. 5 is a scanning electron micrograph of the electrode material prepared in example 3.
Detailed Description
the present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
A preparation method of a graphene @ CoAl-LDH composite electrode material comprises the steps of obtaining graphene oxide aerogel through freeze drying; preparing a mixed solution of the CoAl; carrying out hydrothermal reaction on the graphene aerogel and a CoAl mixed solution, and carrying out freeze drying when the temperature is reduced to room temperature to obtain the graphene @ CoAl-LDH composite electrode material, wherein the method comprises the following specific steps:
(1) Preparation of graphene oxide aerogel
Preparing graphene oxide by using an improved Hummer method, mixing the prepared graphene oxide with deionized water according to a mass ratio of 1:2-3:2, carrying out ultrasonic treatment for 1-2h, and then carrying out freeze drying on a graphene oxide aqueous solution for 1-8h to obtain the graphene oxide aerogel.
(2) Preparation of CoAl Mixed solution
stirring and mixing a cobalt salt and deionized water according to a ratio of 2mg:1ml-20mg:1ml for 15-30min, stirring and mixing an aluminum salt and deionized water according to a ratio of 2mg:1ml-10mg:1ml for 15-30min, then mixing the cobalt salt and an aluminum salt solution for 15-30min, wherein the molar ratio of the cobalt salt to the aluminum salt is 5:1-1:1, then adding urea, ammonium fluoride and CTAB, controlling the mass ratio of the cobalt salt to the urea to be 1:1-1:5, the mass ratio of the cobalt salt to the ammonium fluoride to be 6:1-15:1, and the mass ratio of the cobalt salt to the CTAB to be 4:1-1:1, stirring and mixing, wherein the optional cobalt salt is cobalt nitrate, cobalt acetate or cobalt chloride, and the aluminum salt is aluminum nitrate, aluminum acetate or aluminum chloride.
(3) Preparation of graphene @ CoAl-LDH composite electrode material
mixing the prepared graphene oxide aerogel with a CoAl mixed solution according to a mass ratio of 1:10-1:100, carrying out hydrothermal reaction at 110-140 ℃ for 12-24h, cooling to room temperature, replacing with deionized water, and carrying out freeze drying at a drying temperature of-2-20 ℃ for 12-24 h. And preparing the graphene @ CoAl-LDH composite electrode material.
The following are more detailed embodiments, and the technical solutions and the technical effects obtained by the present invention will be further described by the following embodiments.
Example 1
A preparation method of a graphene @ CoAl-LDH composite electrode material comprises the following steps:
(1) Preparation of graphene oxide aerogel
Preparing graphene oxide by using an improved Hummer method, carrying out ultrasonic treatment on the prepared graphene oxide and deionized water according to the ratio of 1:2 for 1h, and carrying out freeze drying for 1h to obtain the required graphene oxide aerogel.
(2) Preparation of CoAl Mixed solution
Preparing a solution of cobalt nitrate and deionized water according to 4mg-1ml, and stirring for 15 min; preparing a solution of aluminum nitrate and deionized water according to 4mg-1ml, and stirring for 15 min; cobalt nitrate and aluminum nitrate solutions were mixed according to 5:1, mixing and stirring for 15min to obtain a mixed CoAl solution; adding cobalt nitrate and urea according to the proportion of 1: 1; adding cobalt nitrate and ammonium fluoride according to the proportion of 6: 1; adding cobalt nitrate and CTAB according to the proportion of 4: 1; the desired CoAl mixed solution was obtained.
(3) Preparation of graphene @ CoAl-LDH composite electrode material
Carrying out hydrothermal reaction treatment on the prepared graphene oxide aerogel and the CoAl mixed solution according to the ratio of 1:10, wherein the hydrothermal reaction time is 12 hours and the temperature is 120 ℃; and (3) cooling to room temperature at the same temperature, then carrying out freeze drying, and controlling the drying temperature to be-10 ℃ for drying for 18h to obtain the required graphene @ CoAl-LDH composite electrode material.
The obtained graphene @ CoAl-LDH composite electrode material powder was scanned by a field emission scanning electron microscope (Zeiss ultra 55, Germany), and the obtained scanning electron microscope image is shown in FIG. 1, and it can be seen from FIG. 1 that the embroidered spherical CoAl bimetal is attached to the surface of the graphene oxide, which indicates that the graphene oxide and the CoAl are fully mixed.
and (3) electrochemical performance testing:
Under the condition of 1mol/LKOH electrolyte, a standard electrode is an inert Pt electrode, a reference electrode is an Ag/AgCl electrode, a working electrode is a Pt net loaded with active substances, and the electrochemical performance of the material is tested by using a three-electrode system in an electrochemical workstation and a blue-ray system. The results show that the prepared composite electrode material is 1Ag-1the charging and discharging curves under the constant current condition are symmetrical triangular, and show good pseudo-capacitance behavior. At a current of 1Ag-1In a circulation stability curve under sweeping speed, the specific capacity of the material has little change, after 5000 times of circulation, the specific capacity can still be kept at about 76 percent, and the material has good circulation stability.
Example 2
A preparation method of a graphene @ CoAl-LDH composite electrode material comprises the following steps:
(1) preparation of graphene oxide aerogel
Preparing graphene oxide by using an improved Hummer method, carrying out ultrasonic treatment on the prepared graphene oxide and deionized water according to the ratio of 1:1 for 1.5h, and carrying out freeze drying for 1.5h to obtain the required graphene oxide aerogel.
(2) Preparation of CoAl Mixed solution
Preparing a solution of cobalt nitrate and deionized water according to the volume of 10mg-1ml, and stirring for 20 min; preparing a solution of aluminum nitrate and deionized water according to the volume of 10mg-1ml, and stirring for 20 min; mixing cobalt nitrate and an aluminum nitrate solution according to a ratio of 4:1, and stirring for 20min to obtain a mixed CoAl solution; adding cobalt nitrate and urea according to the proportion of 1: 2; adding cobalt nitrate and ammonium fluoride according to the proportion of 8: 1; adding cobalt nitrate and CTAB according to the proportion of 3: 1; the desired CoAl mixed solution was obtained.
(3) Preparation of graphene @ CoAl-LDH composite electrode material
Carrying out hydrothermal reaction treatment on the prepared graphene oxide aerogel and the CoAl mixed solution according to the ratio of 1:40, wherein the hydrothermal reaction time is 15h and the temperature is 120 ℃; and (3) cooling to room temperature at the same temperature, then carrying out freeze drying, and controlling the drying temperature to be-5 ℃ for drying for 12h to obtain the required graphene @ CoAl-LDH composite electrode material.
the graphene @ CoAl-LDH composite electrode material powder obtained above was scanned by a field emission scanning electron microscope (Zeiss ultra 55, Germany) instrument, and the obtained scanning electron microscope image is shown in FIG. 2. As can be seen from fig. 2, the embroidered spherical agal bimetal is uniformly attached to the surface of the graphene oxide, and the two metals react sufficiently. The test was performed using an x-ray diffractometer (XRD) at 2-80 deg., as shown in fig. 3, the CoAl peak corresponds to that of the standard card.
The electrochemical performance test method is the same as that in example 1, under the condition of 1mol/LKOH electrolyte, the standard electrode is an inert Pt electrode, the reference electrode is an Ag/AgCl electrode, the working electrode is a Pt net loaded with active substances, and the electrochemical performance of the material is tested by using a three-electrode system at an electrochemical workstation and a blue-ray system. As shown in FIG. 4, the prepared composite electrode material is prepared in 2Ag-1The charge-discharge curve under the constant current condition is symmetrical triangular, shows good pseudo-capacitance behavior, and the current is 2Ag-1The specific capacitance can reach 2243F/g, after 5000 times of circulation, the specific capacitance can still be kept about 90%, and the excellent circulation stability is achieved。
Example 3
a preparation method of a graphene @ CoAl-LDH composite electrode material comprises the following steps:
(1) Preparation of graphene oxide aerogel
preparing graphene oxide by using an improved Hummer method, carrying out ultrasonic treatment on the prepared graphene oxide and deionized water according to a ratio of 3:2 for 2h, and carrying out freeze drying for 2h to obtain the required graphene oxide aerogel.
(2) Preparation of CoAl Mixed solution
Preparing a solution of cobalt nitrate and deionized water according to 20mg-1ml, and stirring for 30 min; preparing a solution of aluminum nitrate and deionized water according to the proportion of 20mg-1ml, and stirring for 30 min; mixing cobalt nitrate and an aluminum nitrate solution according to a ratio of 2:1, and stirring for 30min to obtain a mixed CoAl solution; adding cobalt nitrate and urea according to the proportion of 1: 4; adding cobalt nitrate and ammonium fluoride according to the proportion of 12: 1; adding cobalt nitrate and CTAB according to the proportion of 2: 1; the desired CoAl mixed solution was obtained.
(3) Preparation of graphene @ CoAl-LDH composite electrode material
Carrying out hydrothermal reaction treatment on the prepared graphene oxide aerogel and the CoAl mixed solution according to the ratio of 1:80, wherein the hydrothermal reaction time is 20 hours and the temperature is 140 ℃; and (3) cooling to room temperature at the same temperature, then carrying out freeze drying, and controlling the drying temperature to be-15 ℃ for drying for 15h to obtain the required graphene @ CoAl-LDH composite electrode material.
The graphene @ CoAl-LDH composite electrode material powder obtained above was scanned by a field emission scanning electron microscope (Zeiss ultra 55, Germany) instrument, and the obtained scanning electron microscope image is shown in FIG. 5. From fig. 5, it can be seen that the embroidered spherical agal bimetal is excessively attached to the surface of the graphene oxide, and the sufficient reaction between the embroidered spherical agal bimetal and the graphene oxide is proved, but the material loading is too much, so that the test of the electrochemical performance is influenced.
And (3) electrochemical performance testing:
Under the condition of 1mol/LKOH electrolyte, the standard electrode is an inert Pt electrode, the reference electrode is an Ag/AgCl electrode, the working electrode is a Pt net loaded with active substances, and the three-electrode system is used for electrochemical reactionThe chemical workstation and the blue system test the electrochemical performance of the material. The prepared composite electrode material is prepared in 2Ag-1The charge and discharge curves under the constant current condition are symmetrical and triangular, the good pseudo-capacitance behavior is shown, after 5000 cycles, the specific capacity can still be kept at about 70%, and the test of the electrochemical performance is influenced due to excessive load of the composite electrode material.
Example 4
A preparation method of a graphene @ CoAl-LDH composite electrode material comprises the following steps:
(1) Preparation of graphene oxide aerogel
preparing graphene oxide by using an improved Hummer method, carrying out ultrasonic treatment on the prepared graphene oxide and deionized water according to a ratio of 3:2 for 1h, and carrying out freeze drying for 4h to obtain the required graphene oxide aerogel.
(2) Preparation of CoAl Mixed solution
Preparing a solution of cobalt acetate and deionized water according to the volume of 2mg-1ml, and stirring for 20 min; preparing a solution of aluminum acetate and deionized water according to the volume of 2mg-1ml, and stirring for 20 min; cobalt acetate and aluminum acetate solution were mixed according to 3:1, mixing and stirring for 20min to obtain a mixed CoAl solution; adding cobalt acetate and urea according to the proportion of 1: 3; adding cobalt acetate and ammonium fluoride according to the proportion of 10: 1; adding cobalt acetate and CTAB according to the proportion of 1: 1; the desired CoAl mixed solution was obtained.
(3) Preparation of graphene @ CoAl-LDH composite electrode material
Carrying out hydrothermal reaction treatment on the prepared graphene oxide aerogel and the CoAl mixed solution according to the ratio of 1:100, wherein the hydrothermal reaction time is 12 hours and the temperature is 110 ℃; and (3) cooling to room temperature at the same temperature, then carrying out freeze drying, and controlling the drying temperature to be-2 ℃ for drying for 24h to obtain the required graphene @ CoAl-LDH composite electrode material.
And (3) electrochemical performance testing:
Under the condition of 1mol/LKOH electrolyte, a standard electrode is an inert Pt electrode, a reference electrode is an Ag/AgCl electrode, a working electrode is a Pt net loaded with active substances, and the electrochemical performance of the material is tested by using a three-electrode system in an electrochemical workstation and a blue-ray system. KnotThe results show that the prepared composite electrode material is 1Ag-1the charging and discharging curves under the constant current condition are symmetrical triangular, and show good pseudo-capacitance behavior. At a current of 1Ag-1In a circulation stability curve under sweeping speed, the specific capacity of the material has small change, and after 5000 times of circulation, the specific capacity can still be kept at about 80 percent, so that the material has good circulation stability.
Example 5
A preparation method of a graphene @ CoAl-LDH composite electrode material comprises the following steps:
(1) Preparation of graphene oxide aerogel
Preparing graphene oxide by using an improved Hummer method, carrying out ultrasonic treatment on the prepared graphene oxide and deionized water according to a ratio of 1:1 for 2 hours, and carrying out freeze drying for 8 hours to obtain the required graphene oxide aerogel.
(2) preparation of CoAl Mixed solution
preparing a solution of cobalt chloride and deionized water according to 20mg-1ml, and stirring for 30 min; preparing a solution of aluminum chloride and deionized water according to the volume of 10mg-1ml, and stirring for 30 min; cobalt chloride and aluminum chloride solution were mixed according to a 1:1, mixing and stirring for 30min to obtain a mixed CoAl solution; adding cobalt chloride and urea according to the proportion of 1: 5; adding cobalt chloride and ammonium fluoride according to the proportion of 15: 1; adding cobalt chloride and CTAB according to the proportion of 1: 1; the desired CoAl mixed solution was obtained.
(3) preparation of graphene @ CoAl-LDH composite electrode material
Carrying out hydrothermal reaction treatment on the prepared graphene oxide aerogel and the CoAl mixed solution according to the ratio of 1:20, wherein the hydrothermal reaction time is 24 hours and the temperature is 140 ℃; and (3) cooling to room temperature at the same temperature, then carrying out freeze drying, and controlling the drying temperature to be-20 ℃ for drying for 12h to obtain the required graphene @ CoAl-LDH composite electrode material.
And (3) electrochemical performance testing:
Under the condition of 1mol/LKOH electrolyte, the standard electrode is an inert Pt electrode, the reference electrode is an Ag/AgCl electrode, the working electrode is a Pt net loaded with active substances, and the three-electrode system is used as a test material for an electrochemical workstation and a blue-electricity systemThe electrochemical performance of (2). The results show that the prepared composite electrode material is 1Ag-1The charging and discharging curves under the constant current condition are symmetrical triangular, and show good pseudo-capacitance behavior. At a current of 1Ag-1In a circulation stability curve under sweeping speed, the specific capacity of the material has small change, and after 5000 times of circulation, the specific capacity can still be kept at about 80 percent, so that the material has good circulation stability.
in summary, according to the preparation method of the graphene @ CoAl-LDH composite electrode material, disclosed by the invention, the charge and discharge performance, XRD (X-ray diffraction) and scanning electron microscope performance diagrams of all the examples are comprehensively compared, the electrochemical performance prepared in example 2 is the best, the graphene @ CoAl-LDH composite electrode has a specific capacity of 2243F/g in constant-current charge and discharge of 2A/g, nearly 90% of the specific capacity is still kept after 5000 cycles, the good cycle stability is highlighted, and the composite electrode material with good electrochemical performance and mechanical flexibility is prepared by fully utilizing the synergistic effect of a carbon material and a transition metal oxide.
The composite material disclosed by the invention fully utilizes the excellent characteristics of high conductivity and high specific surface area of graphene oxide and the characteristic of high specific capacity of the CoAl bimetallic oxide, fully utilizes the synergistic effect of the graphene oxide and the CoAl bimetallic oxide, and well overcomes the defect of a single metal material.
in the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The embodiments described above are intended to facilitate the understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (10)
1. A preparation method of a graphene @ CoAl-LDH composite electrode material is characterized by comprising the following steps:
Preparation of graphene oxide aerogel
Preparing graphene oxide by using an improved Hummer method, mixing the prepared graphene oxide with deionized water, and freeze-drying to obtain graphene oxide aerogel;
Preparation of CoAl Mixed solution
Stirring and mixing cobalt salt and deionized water to obtain a cobalt salt solution,
Stirring and mixing the acid aluminum salt and the deionized water to obtain an aluminum salt solution,
Mixing a cobalt salt solution and an aluminum salt solution, adding urea, ammonium fluoride and CTAB, and stirring and mixing to obtain a CoAl mixed solution;
Preparation of graphene @ CoAl-LDH composite electrode material
And mixing the graphene oxide aerogel and the CoAl mixed solution, carrying out hydrothermal reaction, cooling to room temperature after the reaction is finished, replacing with deionized water, and freeze-drying to obtain the graphene @ CoAl-LDH composite electrode material.
2. the preparation method of the graphene @ CoAl-LDH composite electrode material as claimed in claim 1, wherein the mixing mass ratio of the graphene oxide to the deionized water is 1:2-3: 2.
3. The preparation method of the graphene @ CoAl-LDH composite electrode material as claimed in claim 1, wherein the control time for preparing the graphene oxide aerogel through freeze drying is 1-8h, the temperature for preparing the graphene @ CoAl-LDH composite electrode material through freeze drying is-2 to-20 ℃, and the time is 12-24 h.
4. The method for preparing the graphene @ CoAl-LDH composite electrode material as claimed in claim 1, wherein the cobalt salt comprises cobalt nitrate, cobalt acetate or cobalt chloride, and the aluminum salt comprises aluminum nitrate, aluminum acetate or aluminum chloride.
5. The preparation method of the graphene @ CoAl-LDH composite electrode material as claimed in claim 1, wherein the mixing ratio of the cobalt salt to the deionized water is 2mg:1ml-20mg:1ml, and the mixing ratio of the aluminum salt to the deionized water is 2mg:1ml-10mg:1 ml.
6. The preparation method of the graphene @ CoAl-LDH composite electrode material as claimed in claim 1, wherein the molar ratio of the cobalt salt to the aluminum salt is 5:1-1: 1.
7. The preparation method of the graphene @ CoAl-LDH composite electrode material as claimed in claim 1, wherein the mass ratio of the cobalt salt to the urea is 1:1-1:5, the mass ratio of the cobalt salt to the ammonium fluoride is 6:1-15:1, and the mass ratio of the cobalt salt to CTAB is 4:1-1: 1.
8. The preparation method of the graphene @ CoAl-LDH composite electrode material as claimed in claim 1, wherein the mass ratio of the graphene oxide aerogel to the CoAl mixed solution is 1:10-1: 100.
9. The preparation method of the graphene @ CoAl-LDH composite electrode material as claimed in claim 1, wherein the temperature of the hydrothermal reaction of the graphene oxide aerogel and the CoAl mixed solution is 12-24h, and the reaction temperature is 110-140 ℃.
10. The graphene @ CoAl-LDH composite electrode material prepared by the method of any one of claims 1-9.
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