CN112863900A - Porous graphene electrode for supercapacitor and preparation method thereof - Google Patents
Porous graphene electrode for supercapacitor and preparation method thereof Download PDFInfo
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- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- 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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- H—ELECTRICITY
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- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- 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
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- 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
- H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
- H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for electrodes
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Abstract
The invention discloses a porous graphene electrode for a supercapacitor and a preparation method thereof, wherein graphene oxide is dispersed in water, and magnetic stirring is carried out to prepare graphene oxide aqueous dispersion; adding porous graphene into the graphene oxide aqueous dispersion, and performing magnetic stirring and ultrasonic dispersion to obtain a dispersion A; adding carbon nano tubes into the dispersion liquid A, adding a binder a, homogenizing, magnetically stirring, and ultrasonically dispersing to prepare a stable dispersion liquid B; adding conductive carbon black into the stable dispersion liquid B, magnetically stirring, and ultrasonically dispersing to prepare a conductive agent dispersion liquid C; and adding the conductive agent dispersion liquid C, the activated carbon and the binder b into deionized water for ultrasonic dispersion, stirring and oscillating in vacuum to prepare a super capacitor slurry, coating the super capacitor slurry on the carbon-coated aluminum foil, drying the coated carbon-coated aluminum foil, then performing vacuum drying treatment and compaction treatment, and cutting into electrodes to package to prepare the super capacitor. The preparation process is simple to operate and high in controllability.
Description
Technical Field
The invention belongs to the technical field of super capacitors, and particularly relates to a porous graphene electrode for a super capacitor and a preparation method thereof.
Background
The super capacitor is a novel energy storage and conversion device for storing energy through an interface double layer formed between an electrode and an electrolyte, and can be divided into a double capacitor, a quasi-faraday capacitor and a hybrid super capacitor according to the energy storage principle. The super capacitor has the advantages of high power density, long cycle charge and discharge life, high charge and discharge efficiency, long energy storage life, high reliability, wide working environment temperature range and the like, and is widely applied. Compared with the traditional capacitor, the double electric layer super capacitor has ultrahigh capacity and ultrahigh power density due to the adoption of the material with ultrahigh specific surface area, and is unique in various energy storage devices.
The super capacitor binder is divided into water-soluble and oil-soluble types. The oil-soluble binder is most widely applied to homopolymers and copolymers of polyvinylidene fluoride (PVDF), and an organic solvent is used as a dispersing agent; the aqueous binder is widely used by styrene butadiene Styrene (SBR) emulsion binder, and water is used as a dispersing agent. In an oil-soluble system, the impedance of the electrolyte and the surface of the electrode and the impedance of an electric double layer are far greater than the impedance of an aqueous system, and under the condition of large current, the diffusion of ion transmission between the electrolyte/the surface of the electrode and the double layers is influenced, so that the rate performance of the electrode is influenced, and therefore the rate performance of the supercapacitor prepared by adopting the aqueous solvent system is obviously superior to that of the oily system. In an organic solvent system represented by NMP, the supercapacitor can generate gas in a long circulation process and react with aluminum foil, so that the stability is poor; the solvent has high recovery cost and can cause certain pollution to the environment.
The currently used electrode materials of the super capacitor mostly adopt carbon material electrode materials, such as graphene, carbon nanotubes, porous carbon fibers and the like, the materials have extremely large specific surface area and extremely high resistivity, and the super capacitor material prepared by using the materials has excellent conductivity. However, in the graphene conductive paste prepared by mixing graphene, activated carbon and the like, the graphene is easy to agglomerate, and the dispersion effect is poor, so that the effect of the prepared super capacitor is greatly reduced. Since at ultra-fast charge rates, the electrodes of the supercapacitor determine the capacitance, energy density and power density of the supercapacitor.
In order to improve the capacitance and energy density of the super capacitor, the development and development of an electrode material with ultrahigh conductivity and specific capacitance become problems to be solved in further development of the super capacitor. Therefore, more and more researchers are trying to prepare a high-performance supercapacitor by improving the graphene dispersion method and improving the electrode conductivity.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a porous graphene electrode for a supercapacitor and a method for preparing the same, which reduces the agglomeration phenomenon of graphene by adding graphene oxide into a porous graphene conductive agent dispersion solution.
The invention adopts the following technical scheme:
a preparation method of a porous graphene electrode for a supercapacitor comprises the steps of dispersing graphene oxide in water, and magnetically stirring to prepare a graphene oxide aqueous dispersion; adding porous graphene into the graphene oxide aqueous dispersion, and performing magnetic stirring and ultrasonic dispersion to obtain a dispersion A; adding carbon nano tubes into the dispersion liquid A, adding a binder a, homogenizing, magnetically stirring, and ultrasonically dispersing to prepare a stable dispersion liquid B; adding conductive carbon black into the stable dispersion liquid B, magnetically stirring, and ultrasonically dispersing to prepare a dispersion liquid C; adding the dispersion liquid C, the activated carbon and the binder b into deionized water for ultrasonic dispersion, stirring and oscillating in vacuum to prepare supercapacitor slurry, coating the supercapacitor slurry on the carbon-coated aluminum foil, drying the coated carbon-coated aluminum foil, and then performing vacuum drying treatment; and compacting the carbon-coated aluminum foil after vacuum drying, and then cutting into electrodes to be packaged to prepare the super capacitor.
Specifically, the porous graphene is high-conductivity porous graphene rapidly self-made by high-energy microwaves in a laboratory, and the microwave action time is controlled to be 10-120 s in the process of preparing the porous graphene by the microwave method; controlling the power of the microwave action of each gram of raw materials to be 200-700W; the oxidizing atmosphere is air; the purified porous graphene atmosphere is argon.
Specifically, the mass percentage of the porous graphene, the graphene oxide and the carbon nanotube is 70%: (1-29%): (29-1%) and the mass of the binder a accounts for 2-4% of the mass percent of the total slurry solids.
Specifically, the conductive carbon black accounts for 1-9% of the solid mass of the slurry, and is one or a mixture of more of Super-dense high Ks-6 and Ks-15 conductive graphite, cabot XC72 conductive carbon black, Ketjen black, acetylene black, SuperP and/or SuperS.
Specifically, the mass ratio of the modifier consisting of porous graphene, graphene oxide and carbon nanotubes to the binder a, the conductive carbon black, the activated carbon and the binder b is (1-9%): 4%: (9-1%): 80%: 6 percent and the solid content of the total slurry is 22 to 25 percent.
Specifically, the thickness of the carbon-coated aluminum foil is 15-20 microns, and the coating thickness of the electrode slurry is 100-200 microns; the drying temperature is 70-95 ℃ for 2-3 hours, and the vacuum drying temperature is 80-100 ℃ for 8-12 hours.
Specifically, the speed of magnetic stirring is 100-300 rpm/min, the time of ultrasonic dispersion is 0.5-4 hours, and the power of ultrasonic is 500-2000W.
Specifically, the binder a and the binder b are sodium carboxymethylcellulose, polytetrafluoroethylene, polyacrylonitrile, styrene-butadiene emulsion or aqueous polyacrylic emulsion.
Specifically, an electric double-roller machine is adopted for compaction treatment, and the temperature is 60-80 ℃.
The invention also provides a porous graphene electrode for the supercapacitor.
Compared with the prior art, the invention has at least the following beneficial effects:
the invention innovatively provides a preparation method of an improved porous graphene supercapacitor conductive agent for a supercapacitor, the volume of a pole piece made of a new improved electrode material is introduced and is almost unchanged, the specific capacitance and the rate capability of the manufactured supercapacitor are obviously improved, and the volume energy density is improved. The preparation process of the supercapacitor slurry is simple, the cost is low, the used materials are environment-friendly, non-toxic and pollution-free, and the supercapacitor slurry can be applied in a large scale. Graphene as a novel material has extremely high specific surface area, is an ideal material for preparing a supercapacitor electrode, but has poor dispersibility, so that the application of the graphene in the supercapacitor is severely restricted. According to the invention, the dispersion means of graphene is improved, so that the graphene dispersion effect is better, the improved graphene material has no influence on the quality and volume of the active carbon electrode, the graphene dispersion is improved, meanwhile, the electrode structure is improved by adding graphene oxide and carbon nano tubes, and the conductivity of the electrode of the super capacitor is improved, so that the rate capability and specific capacitance of the super capacitor are improved, and the method has important significance for enhancing the energy density of the super capacitor and promoting the large-scale application of the super capacitor.
Furthermore, the time for deep processing of the self-made porous graphene by adopting a microwave method is shorter, the efficiency is higher, and the energy utilization rate is higher. Impurity functional groups on the graphene sheet layer can be removed, so that the prepared improved nano porous graphene is higher in purity, the specific surface area of the graphene is increased, and the energy density of the supercapacitor is improved.
Furthermore, the graphene oxide is adopted for assisting in dispersion, a new dispersing agent is not introduced, the dispersion effect of the graphene is improved, the graphene oxide can be reduced through high-temperature annealing, the conductivity of the electrode material is further enhanced, and the proportion of the electrode active material is favorably improved.
Furthermore, the conductive carbon black has extremely low resistivity, and the high-rate working performance of the super capacitor can be improved by adopting the conductive carbon black with proper mass percentage; the conductive carbon black has larger specific surface area, can effectively increase the contact area with the electrolyte, increase the specific capacity of the super capacitor and enhance the electrochemical performance of the super capacitor.
Furthermore, the porous graphene as one of the conductive agents has poor compatibility, and if the porous graphene is directly added into the electrode slurry, the dispersion effect is poor and the dispersion time is long; the conductive agent can be more uniformly dispersed in the electrode slurry by preparing the conductive agent dispersion liquid, so that the dispersion time of the conductive agent is shortened, and the dispersion efficiency and the dispersion effect of the conductive agent are improved.
Further, vacuum stirring not only can make thick liquids dispersion efficiency higher, and the thick liquids homogeneity is good, can also make the gas in the thick liquids deviate from, prevents moisture or impure gas's package clamp, makes thick liquids thickness when the coating more even, and pole piece surface is more level and more smooth after the drying, still can eliminate the bubble through adding one or more low-speed stirring in a small amount of ethanol, the n-butanol, further shortens vacuum drying's time, improves production efficiency.
Furthermore, magnetic stirring is adopted as the dispersion pretreatment, so that the materials are uniformly dispersed. Compared with a common stirrer, the magnetic stirring stirrer has the advantages of low noise, stable speed regulation, convenient use, temperature regulation and rotating speed regulation, and visual and accurate digital display, and can ensure that the slurry is mixed in a closed container. And the ultrasonic treatment is adopted to further improve the dispersion quality and reduce the dispersion cost. The ultrasonic dispersion utilizes the in-situ oscillation of fluid molecules, has good local dispersion effect, can make local components of materials more uniform, and has better dispersion effect by combining the two components.
Furthermore, the invention adopts the aqueous solvent system to prepare the slurry, and in the aspect of industrial processing, because the aqueous binder has good freeze-thaw resistance, does not break emulsion under high-speed shearing, has excellent grinding stability, is very suitable for being dispersed with powder, and has very high processing stability and operability.
Furthermore, the thickness and the compaction density of the pressed pole piece can be accurately controlled by adopting the electric double-roll machine, and the rolling precision is ensured.
Furthermore, the compaction density of the super capacitor pole piece prepared by the method can be comparable to that of oily PVDF, and compared with the traditional graphene-based super capacitor, the super capacitor prepared by the method has excellent rate capability and higher specific capacitance, and can meet the requirement of high-rate charge and discharge; the super capacitor has excellent heat dissipation performance, improves the high and low temperature performance of the super capacitor, and prolongs the service life of the super capacitor.
In conclusion, the preparation process is simple to operate and high in controllability. The optimal proportion obtained by a plurality of experiments can control the viscosity degree of the slurry and the coating thickness, and can realize large-scale and batch production.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a comparison of Nyquist plots for an example of the present invention;
FIG. 2 is a graph comparing CV diagrams for an example of the present invention;
FIG. 3 is a graph of a comparison of charge and discharge cycles of an embodiment of the present invention;
fig. 4 is a graph comparing charge and discharge cycle rate performance of examples of the present invention related to rate performance.
FIG. 5 is a graph comparing charge and discharge long cycle performance of various examples of the invention in relation to cycle performance.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
Various structural schematics according to the disclosed embodiments of the invention are shown in the drawings. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, according to actual needs.
The invention provides a porous graphene electrode for a supercapacitor and a preparation method thereof, wherein a water-soluble binder is adopted, deionized water is used as a solvent to prepare the porous graphene supercapacitor, and graphene oxide contains a large number of hydrophobic conjugate zones, epoxy groups and hydroxyl groups on a basal plane and more hydrophilic carboxyl groups on the edge, so that the graphene oxide has special amphipathy, can be stably dispersed in a solution, and can disperse graphene through pi-pi interaction of the conjugate basal plane, thereby further improving the dispersibility of the graphene in an aqueous solution and enhancing the dispersion effect of the porous graphene.
In order to enhance the conductivity of the graphene slurry, the conductivity of the graphene slurry is improved by adding a small amount of carbon nanotubes into the dispersion liquid. CNTs with the pipe diameter less than 6nm can be regarded as one-dimensional quantum wires with good conductivity and good conductivity. Meanwhile, the large pi bond on the outer surface of the carbon nanotube allows the carbon nanotube to be compounded with macromolecules with conjugated performance by non-covalent bonds, so that the carbon nanotube plays a role in improving the conductivity in dispersion liquid and does not influence the dispersibility of the carbon nanotube. In addition, the added carbon nano tube has an electric double layer effect, so that the high rate performance of the super capacitor can be exerted, the good heat conduction performance of the super capacitor is also beneficial to heat dissipation of the battery during charging and discharging, the polarization of the battery is reduced, the high and low temperature performance of the super capacitor is improved, and the service life of the super capacitor is prolonged. The supercapacitor conductive agent prepared by the method is compounded with activated carbon with a large specific surface area to prepare improved graphene supercapacitor slurry, so that the supercapacitor with high energy density, high charge-discharge efficiency and long cycle life is prepared innovatively.
The invention discloses a preparation method of a porous graphene electrode for a supercapacitor, which comprises the following steps:
s1, dispersing graphene oxide in water, and magnetically stirring to prepare a graphene oxide water dispersion;
the magnetic stirring speed is 100-300 rpm/min.
S2, adding porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, and performing magnetic stirring and ultrasonic dispersion to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, adding a binder a, homogenizing, magnetically stirring, and ultrasonically dispersing to prepare a stable dispersion liquid B;
the mass percentage of the porous graphene, the graphene oxide and the carbon nano tube in the modifier is 70%: (1-29%): (29% -1%) porous graphene is high-conductivity porous graphene rapidly self-made by high-energy microwaves in a laboratory, and in the process of preparing the porous graphene by the microwave method, the microwave action time is controlled to be 10-120 s.
The speed of magnetic stirring is 100-300 rpm/min, the time of ultrasonic dispersion is 0.5-4 hours, and the power of ultrasonic is 500-2000W.
In the process of preparing the porous graphene by the microwave method, the power of the microwave action of each gram of raw material is controlled to be 200-700W; the oxidizing atmosphere used for the microwave action is air; the purified porous graphene atmosphere is argon.
The speed of magnetic stirring is 100-300 rpm/min, the time of ultrasonic dispersion is 0.5-4 hours, and the power of ultrasonic is 500-2000W.
The binder a is a water-based binder such as sodium carboxymethylcellulose (CMC), Polytetrafluoroethylene (PTFE), Polyacrylonitrile (PAN), styrene-butadiene (SBR) emulsion, aqueous polyacrylic acid (PAA) emulsion and the like.
S4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, and preparing a conductive agent dispersion liquid C through magnetic stirring and ultrasonic dispersion;
the conductive carbon black is one or more of dense high Ks-6 and Ks-15 conductive graphite, cabot XC72 conductive carbon black, Ketjen black, acetylene black, SuperP and/or SuperS.
The magnetic stirring speed is 100-300 rpm/min, the ultrasonic dispersion time is 0.5-4 hours, and the ultrasonic power is 500-2000W.
S5, adding deionized water into the conductive agent dispersion liquid C, the activated carbon and the binder b prepared in the step S4 for ultrasonic dispersion, placing the mixture into a vacuum stirrer for vibration to prepare supercapacitor slurry, coating the supercapacitor slurry on a carbon-coated aluminum foil, placing the coated carbon-coated aluminum foil into a blast oven for drying treatment, and placing the treated carbon-coated aluminum foil into a vacuum oven for vacuum treatment;
the binder b is a water-based binder such as sodium carboxymethylcellulose (CMC), Polytetrafluoroethylene (PTFE), Polyacrylonitrile (PAN), Styrene Butadiene (SBR) emulsion, aqueous polyacrylic acid (PAA) emulsion and the like.
The mass ratio of the modifier to the binder a to the conductive carbon black to the active carbon to the binder b is (1-9%): 4%: (9-1%): 80%: 6 percent.
The ultrasonic dispersion time is 0.5-4 hours, the ultrasonic power is 500-2000W, and the vacuum stirring speed is 200-1000 rpm/min.
The thickness of the carbon-coated aluminum foil is 15-20 microns, preferably 16 microns, and the coating thickness of the electrode slurry is 100-200 microns.
The temperature of the air-blast oven is set to be 70-95 ℃ for 2-3 hours, and the temperature of the vacuum drying treatment is set to be 80-100 ℃ for 8-12 hours.
And S6, putting the dried carbon-coated aluminum foil into an electric double-roller machine for compaction, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into the super capacitor.
The thickness of the roller press is 10% -20% before rolling, the temperature is set to be 60-80 ℃, and multiple times of rolling are carried out.
According to the porous graphene electrode for the supercapacitor, disclosed by the invention, an excellent conductive network can be constructed in electrode slurry by adjusting the compounding of the porous graphene and the conductive agent, so that the overall conductive performance of the electrode is improved; the graphene has a porous structure, the laminar graphene has smaller tortuosity for transporting ions, the transportation of the ions is accelerated, the prepared electrode material has good multiplying power performance and capacitance retention rate, the specific capacitance of the prepared electrode material can reach more than 110F/g by improving the proportion of the electrode material, and meanwhile, the energy density can be improved to 100 Wh/kg.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
S1, dispersing graphene oxide in water, and controlling the magnetic stirring speed to be 300rpm/min to prepare graphene oxide aqueous dispersion;
s2, controlling the microwave action time to be 40S and the microwave action power of each gram of raw material to be 400W; the oxidizing atmosphere used for the microwave action is air; preparing porous graphene by using a microwave method under the condition that the purified porous graphene atmosphere is argon, adding the prepared porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then performing ultrasonic dispersion for 1.5 hours at 1200W to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, wherein the mass ratio of the porous graphene to the oxidized graphene to the carbon nanotubes is 7: 1: 2. then adding a binder a, wherein the binder a is sodium carboxymethylcellulose (CMC), the mass of the binder a accounts for 4% of the total solid mass of the slurry, homogenizing, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then ultrasonically dispersing for 1.5 hours at 1200W to prepare a stable dispersion liquid B;
s4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, wherein the conductive carbon black is Super P, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then carrying out ultrasonic dispersion at 1200W for 1.5 hours to prepare a dispersion liquid C;
s5, adding the dispersion liquid C prepared in the step S4, activated carbon and a binder b into deionized water, and ultrasonically dispersing for 1.5 hours at 1200W, wherein the binder b is Styrene Butadiene (SBR) emulsion. Wherein the mass ratio of the modifier to the binder a to the conductive carbon black to the active carbon to the binder b is 1%: 4%: 9%: 80%: 6 percent of the total solid content of the slurry is 23 percent, the slurry is placed in a vacuum mixer to be vibrated to prepare the slurry of the super capacitor, the vacuum stirring speed is 300rpm/min, the slurry is coated on the carbon-coated aluminum foil, the coating thickness of the electrode slurry is 100 microns, the coated carbon-coated aluminum foil is placed in a forced air oven to be dried for 2 hours, the temperature of the forced air oven is 80 ℃, the treated carbon-coated aluminum foil is placed in a vacuum oven to be subjected to vacuum treatment, the temperature of the vacuum drying treatment is set to be 80 ℃, and the time is 8 hours;
and S6, placing the dried carbon-coated aluminum foil into an electric double-roller machine, setting the temperature to be 60 ℃, performing rolling compaction for multiple times, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into a super capacitor for performing electrochemical test and charge and discharge test.
Referring to fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, in the present embodiment, porous graphene is adjusted to be compounded with a modifier, and a small amount of carbon nanotubes and graphene oxide are added to improve the conductivity and the dispersibility of the porous graphene, so that an excellent conductive network can be constructed in an electrode slurry, and the overall conductivity and rate capability of an electrode are improved. The graphene has a porous structure, the laminar graphene has smaller tortuosity for transporting ions, the transportation of the ions is accelerated, the prepared electrode material has good multiplying power performance and capacitance retention rate, the specific capacitance of the prepared electrode material can reach more than 110F/g by improving the proportion of the electrode material, and meanwhile, the energy density can be improved to 100 Wh/kg. The supercapacitor conductive modifier prepared by the method is compounded with activated carbon with a large specific surface area to prepare improved graphene supercapacitor slurry, so that the supercapacitor with high energy density, high charge-discharge efficiency and long cycle life is prepared innovatively.
Example 2
S1, dispersing graphene oxide in water, and controlling the magnetic stirring speed to be 300rpm/min to prepare graphene oxide aqueous dispersion;
s2, controlling the microwave action time to be 10S and the microwave action power per gram of raw material to be 200W; the oxidizing atmosphere used for the microwave action is air; preparing porous graphene by using a microwave method under the condition that the purified porous graphene atmosphere is argon, adding the prepared porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then performing ultrasonic dispersion for 1.5 hours at 1200W to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, wherein the mass ratio of the porous graphene to the oxidized graphene to the carbon nanotubes is 7: 1: 2. then adding a binder a, wherein the binder a is sodium carboxymethylcellulose (CMC), the mass of the binder a accounts for 4% of the total solid mass of the slurry, homogenizing, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then ultrasonically dispersing for 1.5 hours at 1200W to prepare a stable dispersion liquid B;
s4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, wherein the conductive carbon black is Super P, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then carrying out ultrasonic dispersion at 1200W for 1.5 hours to prepare a dispersion liquid C;
s5, adding the dispersion liquid C prepared in the step S4, activated carbon and a binder b into deionized water, and ultrasonically dispersing for 1.5 hours at 1200W, wherein the binder b is Styrene Butadiene (SBR) emulsion. Wherein the mass ratio of the modifier to the binder a to the conductive carbon black to the active carbon to the binder b is 1%: 4%: 9%: 80%: 6 percent of the total solid content of the slurry is 23 percent, the slurry is placed in a vacuum mixer to be vibrated to prepare the slurry of the super capacitor, the vacuum stirring speed is 300rpm/min, the slurry is coated on the carbon-coated aluminum foil, the coating thickness of the electrode slurry is 100 microns, the coated carbon-coated aluminum foil is placed in a forced air oven to be dried for 2 hours, the temperature of the forced air oven is 80 ℃, the treated carbon-coated aluminum foil is placed in a vacuum oven to be subjected to vacuum treatment, the temperature of the vacuum drying treatment is set to be 80 ℃, and the time is 8 hours;
and S6, placing the dried carbon-coated aluminum foil into an electric double-roller machine, setting the temperature to be 60 ℃, performing rolling compaction for multiple times, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into a super capacitor for performing electrochemical test and charge and discharge test.
Referring to fig. 1 and 4, in the present embodiment, the pore size and the number of pores in the generated graphene are controlled by changing the time of the microwave action and the power of the microwave action, so as to change the specific surface area of the porous graphene. Under the condition of too little microwave action time and too little microwave action power, the specific surface area of the generated porous graphene is smaller, and the specific capacitance is lower. Comparative example 1 can illustrate that controlling appropriate microwave action time, microwave action power and other factors affecting the size and number of pores generated in graphene can increase the specific surface area of porous graphene and improve the specific capacitance of a supercapacitor.
Example 3
S1, dispersing graphene oxide in water, and controlling the magnetic stirring speed to be 300rpm/min to prepare graphene oxide aqueous dispersion;
s2, controlling the microwave action time to be 120S and the microwave action power per gram of raw material to be 700W; the oxidizing atmosphere used for the microwave action is air; preparing porous graphene by using a microwave method under the condition that the purified porous graphene atmosphere is argon, adding the prepared porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then performing ultrasonic dispersion for 1.5 hours at 1200W to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, wherein the mass ratio of the porous graphene to the oxidized graphene to the carbon nanotubes is 7: 1: 2. then adding a binder a, wherein the binder a is sodium carboxymethylcellulose (CMC), the mass of the binder a accounts for 4% of the total solid mass of the slurry, homogenizing, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then ultrasonically dispersing for 1.5 hours at 1200W to prepare a stable dispersion liquid B;
s4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, wherein the conductive carbon black is Super P, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then carrying out ultrasonic dispersion at 1200W for 1.5 hours to prepare a dispersion liquid C;
s5, adding the dispersion liquid C prepared in the step S4, activated carbon and a binder b into deionized water, and ultrasonically dispersing for 1.5 hours at 1200W, wherein the binder b is Styrene Butadiene (SBR) emulsion. Wherein the mass ratio of the modifier to the binder a to the conductive carbon black to the active carbon to the binder b is 1%: 4%: 9%: 80%: 6 percent of the total solid content of the slurry is 23 percent, the slurry is placed in a vacuum mixer to be vibrated to prepare the slurry of the super capacitor, the vacuum stirring speed is 300rpm/min, the slurry is coated on the carbon-coated aluminum foil, the coating thickness of the electrode slurry is 100 microns, the coated carbon-coated aluminum foil is placed in a forced air oven to be dried for 2 hours, the temperature of the forced air oven is 80 ℃, the treated carbon-coated aluminum foil is placed in a vacuum oven to be subjected to vacuum treatment, the temperature of the vacuum drying treatment is set to be 80 ℃, and the time is 8 hours;
and S6, placing the dried carbon-coated aluminum foil into an electric double-roller machine, setting the temperature to be 60 ℃, performing rolling compaction for multiple times, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into a super capacitor for performing electrochemical test and charge and discharge test.
Referring to fig. 1 and 4, in the present embodiment, the pore size and the number of pores in the generated graphene are controlled by changing the time of the microwave action and the power of the microwave action, so as to change the specific surface area of the porous graphene. Under the condition of overlong microwave action time and overlarge microwave action power, the specific surface area of the generated porous graphene is not obviously improved, the pore diameter of the generated pores is gradually increased, the specific capacitance is not obviously improved, and more energy is consumed. Comparative example 1 can show that controlling appropriate microwave action time, microwave action power and other factors affecting the size and number of pores generated in graphene can increase the specific surface area of porous graphene, improve the specific capacitance of a supercapacitor, and reduce unnecessary energy loss.
Example 4
S1, dispersing graphene oxide in water, and controlling the speed of magnetic stirring to be 100rpm/min to prepare graphene oxide aqueous dispersion;
s2, controlling the microwave action time to be 40S and the microwave action power of each gram of raw material to be 400W; the oxidizing atmosphere used for the microwave action is air; preparing porous graphene by using a microwave method under the condition that the purified porous graphene atmosphere is argon, adding the prepared porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, controlling the speed of magnetic stirring to be 100rpm/min for magnetic stirring, and then performing ultrasonic dispersion for 0.5 hour at 500W to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, wherein the mass ratio of the porous graphene to the oxidized graphene to the carbon nanotubes is 7: 1: 2. then adding a binder a, wherein the binder a is sodium carboxymethylcellulose (CMC), the mass of the binder a accounts for 4% of the total solid mass of the slurry, homogenizing, controlling the speed of magnetic stirring to 100rpm/min for magnetic stirring, and then ultrasonically dispersing for 0.5 hour at 500W to prepare a stable dispersion liquid B;
s4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, wherein the conductive carbon black is Super P, controlling the speed of magnetic stirring to be 100rpm/min for magnetic stirring, and then carrying out ultrasonic dispersion at 500W for 0.5 hour to prepare a dispersion liquid C;
s5, adding the dispersion liquid C prepared in the step S4, activated carbon and a binder b into deionized water, and ultrasonically dispersing for 0.5 hour at 500W, wherein the binder b is Styrene Butadiene (SBR) emulsion. Wherein the mass ratio of the modifier to the binder a to the conductive carbon black to the active carbon to the binder b is 1%: 4%: 9%: 80%: 6 percent, the solid content of the total slurry is 23 percent, the slurry is placed in a vacuum mixer to be vibrated to prepare the slurry of the super capacitor, the vacuum stirring speed is 100rpm/min, the slurry is coated on the carbon-coated aluminum foil, the coating thickness of the electrode slurry is 100 microns, the coated carbon-coated aluminum foil is placed in a forced air oven to be dried for 2 hours, the temperature of the forced air oven is 80 ℃, the treated carbon-coated aluminum foil is placed in a vacuum oven to be subjected to vacuum treatment, the temperature of the vacuum drying treatment is set to be 80 ℃, and the time is 8 hours;
and S6, placing the dried carbon-coated aluminum foil into an electric double-roller machine, setting the temperature to be 60 ℃, performing rolling compaction for multiple times, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into a super capacitor for performing electrochemical test and charge and discharge test.
Referring to fig. 1 and 4, in the present embodiment, by controlling and changing the magnetic stirring speed, the vacuum stirring speed, the ultrasonic dispersion action power and the action time, the dispersion effect of the slurry is deteriorated, and the conductivity and the specific capacitance of the electrode material are decreased, and in comparison with example 1, it can be explained that controlling the proper magnetic stirring speed, the vacuum stirring speed, the ultrasonic dispersion action time, the action power, and other factors affecting the dispersion of the slurry can improve the conductivity of the electrode material, which is helpful for constructing a uniform conductive network and increasing the specific capacitance of the supercapacitor.
Example 5
S1, dispersing graphene oxide in water, and controlling the magnetic stirring speed to be 300rpm/min to prepare graphene oxide aqueous dispersion;
s2, controlling the microwave action time to be 40S and the microwave action power of each gram of raw material to be 400W; the oxidizing atmosphere used for the microwave action is air; preparing porous graphene by using a microwave method under the condition that the purified porous graphene atmosphere is argon, adding the prepared porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then performing ultrasonic dispersion for 1.5 hours at 1200W to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, wherein the mass ratio of the porous graphene to the graphene oxide to the carbon nanotubes is 70%: 1%: 29 percent. Then adding a binder a, wherein the binder a is sodium carboxymethylcellulose (CMC), the mass of the binder a accounts for 4% of the total solid mass of the slurry, homogenizing, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then ultrasonically dispersing for 1.5 hours at 1200W to prepare a stable dispersion liquid B;
s4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, wherein the conductive carbon black is Super P, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then carrying out ultrasonic dispersion at 1200W for 1.5 hours to prepare a dispersion liquid C;
s5, adding the dispersion liquid C prepared in the step S4, activated carbon and a binder b into deionized water, and ultrasonically dispersing for 1.5 hours at 1200W, wherein the binder b is Styrene Butadiene (SBR) emulsion. Wherein the mass ratio of the modifier to the binder a to the conductive carbon black to the active carbon to the binder b is 1%: 4%: 9%: 80%: 6 percent of the total solid content of the slurry is 23 percent, the slurry is placed in a vacuum mixer to be vibrated to prepare the slurry of the super capacitor, the vacuum stirring speed is 300rpm/min, the slurry is coated on the carbon-coated aluminum foil, the coating thickness of the electrode slurry is 100 microns, the coated carbon-coated aluminum foil is placed in a forced air oven to be dried for 2 hours, the temperature of the forced air oven is 80 ℃, the treated carbon-coated aluminum foil is placed in a vacuum oven to be subjected to vacuum treatment, the temperature of the vacuum drying treatment is set to be 80 ℃, and the time is 8 hours;
and S6, placing the dried carbon-coated aluminum foil into an electric double-roller machine, setting the temperature to be 60 ℃, performing rolling compaction for multiple times, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into a super capacitor for performing electrochemical test and charge and discharge test.
Referring to fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, in the present embodiment, factors such as the ratio of graphene oxide to carbon nanotubes are changed by controlling the modifier, so that the ratio of graphene oxide is reduced, the dispersion effect of graphene is deteriorated, and the rate capability and specific capacitance of the capacitor are reduced. Comparative example 1 can show that controlling the ratio of graphene oxide to carbon nanotubes in the modifier can improve the dispersibility of the electrode material, construct a space conductive network of the electrode material, and contribute to improving the specific capacitance and rate capability of the supercapacitor.
Example 6
S1, dispersing graphene oxide in water, and controlling the magnetic stirring speed to be 300rpm/min to prepare graphene oxide aqueous dispersion;
s2, controlling the microwave action time to be 40S and the microwave action power of each gram of raw material to be 400W; the oxidizing atmosphere used for the microwave action is air; preparing porous graphene by using a microwave method under the condition that the purified porous graphene atmosphere is argon, adding the prepared porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then performing ultrasonic dispersion for 1.5 hours at 1200W to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, wherein the mass ratio of the porous graphene to the graphene oxide to the carbon nanotubes is 70%: 29%: 1 percent. Then adding a binder a, wherein the binder a is sodium carboxymethylcellulose (CMC), the mass of the binder a accounts for 4% of the total solid mass of the slurry, homogenizing, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then ultrasonically dispersing for 1.5 hours at 1200W to prepare a stable dispersion liquid B;
s4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, wherein the conductive carbon black is Super P, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then carrying out ultrasonic dispersion at 1200W for 1.5 hours to prepare a dispersion liquid C;
s5, adding the dispersion liquid C prepared in the step S4, activated carbon and a binder b into deionized water, and ultrasonically dispersing for 1.5 hours at 1200W, wherein the binder b is Styrene Butadiene (SBR) emulsion. Wherein the mass ratio of the modifier to the binder a to the conductive carbon black to the active carbon to the binder b is 1%: 4%: 9%: 80%: 6 percent of the total solid content of the slurry is 23 percent, the slurry is placed in a vacuum mixer to be vibrated to prepare the slurry of the super capacitor, the vacuum stirring speed is 300rpm/min, the slurry is coated on the carbon-coated aluminum foil, the coating thickness of the electrode slurry is 100 microns, the coated carbon-coated aluminum foil is placed in a forced air oven to be dried for 2 hours, the temperature of the forced air oven is 80 ℃, the treated carbon-coated aluminum foil is placed in a vacuum oven to be subjected to vacuum treatment, the temperature of the vacuum drying treatment is set to be 80 ℃, and the time is 8 hours;
and S6, placing the dried carbon-coated aluminum foil into an electric double-roller machine, setting the temperature to be 60 ℃, performing rolling compaction for multiple times, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into a super capacitor for performing electrochemical test and charge and discharge test.
Referring to fig. 1 and 4, in the present embodiment, by controlling factors such as the ratio of the graphene oxide to the carbon nanotubes in the modifier, the ratio of the carbon nanotubes is reduced, so that the conductivity of the slurry is reduced, and the conductivity of the supercapacitor is reduced. The carbon nano tube is an excellent conductive agent, and the comparison of example 1 shows that the proportion of the graphene oxide and the carbon nano tube in the modifier is controlled, so that the dispersibility of the porous graphene can be improved, the conductivity of the slurry can be effectively improved, the charge transfer resistance of the supercapacitor can be reduced, and the conductivity of the electrode material can be improved.
Example 7
S1, dispersing graphene oxide in water, and controlling the magnetic stirring speed to be 300rpm/min to prepare graphene oxide aqueous dispersion;
s2, controlling the microwave action time to be 40S and the microwave action power of each gram of raw material to be 400W; the oxidizing atmosphere used for the microwave action is air; preparing porous graphene by using a microwave method under the condition that the purified porous graphene atmosphere is argon, adding the prepared porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then performing ultrasonic dispersion for 1.5 hours at 1200W to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, wherein the mass ratio of the porous graphene to the oxidized graphene to the carbon nanotubes is 7: 1: 2. then adding a binder a, wherein the binder a is sodium carboxymethylcellulose (CMC), the mass of the binder a accounts for 4% of the total solid mass of the slurry, homogenizing, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then ultrasonically dispersing for 1.5 hours at 1200W to prepare a stable dispersion liquid B;
s4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, wherein the conductive carbon black is Super P, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then carrying out ultrasonic dispersion at 1200W for 1.5 hours to prepare a dispersion liquid C;
s5, adding the dispersion liquid C prepared in the step S4, activated carbon and a binder b into deionized water, and ultrasonically dispersing for 1.5 hours at 1200W, wherein the binder b is Styrene Butadiene (SBR) emulsion. Wherein the mass ratio of the modifier to the binder a to the conductive carbon black to the active carbon to the binder b is 9%: 4%: 1%: 80%: 6 percent of the total solid content of the slurry is 23 percent, the slurry is placed in a vacuum mixer to be vibrated to prepare the slurry of the super capacitor, the vacuum stirring speed is 300rpm/min, the slurry is coated on the carbon-coated aluminum foil, the coating thickness of the electrode slurry is 100 microns, the coated carbon-coated aluminum foil is placed in a forced air oven to be dried for 2 hours, the temperature of the forced air oven is 80 ℃, the treated carbon-coated aluminum foil is placed in a vacuum oven to be subjected to vacuum treatment, the temperature of the vacuum drying treatment is set to be 80 ℃, and the time is 8 hours;
and S6, placing the dried carbon-coated aluminum foil into an electric double-roller machine, setting the temperature to be 60 ℃, performing rolling compaction for multiple times, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into a super capacitor for performing electrochemical test and charge and discharge test.
Referring to fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, in the present embodiment, the ratio of the modifier to the conductive carbon black is controlled to reduce the ratio of the conductive carbon black and increase the ratio of the modifier, so that the specific capacity of the capacitor is improved, and other performances are basically unchanged, but the cost is also increased. The comparative example 1 can show that the proportion of the modifier to the conductive carbon black is controlled, the modification capacity of the porous graphene can be fully exerted, so that the specific capacitance of the supercapacitor is improved, and the proper proportion of the modifier to the conductive carbon black is beneficial to reducing the production cost and facilitating large-scale production.
Example 8
S1, dispersing graphene oxide in water, and controlling the magnetic stirring speed to be 300rpm/min to prepare graphene oxide aqueous dispersion;
s2, controlling the microwave action time to be 40S and the microwave action power of each gram of raw material to be 400W; the oxidizing atmosphere used for the microwave action is air; preparing porous graphene by using a microwave method under the condition that the purified porous graphene atmosphere is argon, adding the prepared porous graphene into the graphene oxide aqueous dispersion prepared in the step S1, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then performing ultrasonic dispersion for 1.5 hours at 1200W to obtain a dispersion A;
s3, adding carbon nanotubes into the dispersion liquid A prepared in the step S2, wherein the mass ratio of the porous graphene to the oxidized graphene to the carbon nanotubes is 7: 1: 2. then adding a binder a, wherein the binder a is sodium carboxymethylcellulose (CMC), the mass of the binder a accounts for 4% of the total solid mass of the slurry, homogenizing, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then ultrasonically dispersing for 1.5 hours at 1200W to prepare a stable dispersion liquid B;
s4, adding conductive carbon black into the stable dispersion liquid B prepared in the step S3, wherein the conductive carbon black is Super P, controlling the speed of magnetic stirring to be 300rpm/min for magnetic stirring, and then carrying out ultrasonic dispersion at 1200W for 1.5 hours to prepare a dispersion liquid C;
s5, adding the dispersion liquid C prepared in the step S4, activated carbon and a binder b into deionized water, and ultrasonically dispersing for 1.5 hours at 1200W, wherein the binder b is Styrene Butadiene (SBR) emulsion. Wherein the mass ratio of the binder a to the conductive carbon black to the activated carbon to the binder b is 4%: 10%: 80%: 6 percent of the total solid content of the slurry is 23 percent, the slurry is placed in a vacuum mixer to be vibrated to prepare the slurry of the super capacitor, the vacuum stirring speed is 300rpm/min, the slurry is coated on the carbon-coated aluminum foil, the coating thickness of the electrode slurry is 100 microns, the coated carbon-coated aluminum foil is placed in a forced air oven to be dried for 2 hours, the temperature of the forced air oven is 80 ℃, the treated carbon-coated aluminum foil is placed in a vacuum oven to be subjected to vacuum treatment, the temperature of the vacuum drying treatment is set to be 80 ℃, and the time is 8 hours;
and S6, placing the dried carbon-coated aluminum foil into an electric double-roller machine, setting the temperature to be 60 ℃, performing rolling compaction for multiple times, and then cutting the carbon-coated aluminum foil into electrodes to be packaged into a super capacitor for performing electrochemical test and charge and discharge test.
Referring to fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5, in the present embodiment, the ratio of the modifier to the conductive carbon black is controlled, so that the components of the modifier are removed, and the rate capability and specific capacitance of the capacitor are reduced. Comparative example 1 can show that the modification capability of the porous graphene can be fully exerted by adding the modifier, the rate capability of the supercapacitor is obviously improved, and the specific capacitance and the energy density of the supercapacitor are improved.
In summary, according to the porous graphene electrode for the supercapacitor and the preparation method thereof, disclosed by the invention, the porous graphene supercapacitor is prepared by adopting the water-soluble binder and using deionized water as a solvent, and graphene is dispersed by utilizing the special amphipathy of graphene oxide, so that the dispersibility of graphene in an aqueous solution is further improved, and the dispersion effect of porous graphene is enhanced; the high-rate performance of the porous graphene super capacitor is fully exerted by utilizing the good conductivity, dispersion performance and double electric layer effect of the carbon nano tube, the good heat conduction performance of the porous graphene super capacitor is also beneficial to heat dissipation when a battery is charged and discharged, the polarization of the battery is reduced, the high and low temperature performance of the super capacitor is improved, and the service life of the porous graphene super capacitor is prolonged; by adjusting the compounding of the porous graphene and the conductive agent, an excellent conductive network can be constructed in the electrode slurry, so that the overall conductivity of the electrode is improved; the graphene has a porous structure, and the laminar graphene has smaller tortuosity for transporting ions, so that the transportation of the ions is accelerated, and the prepared graphene electrode material has good rate capability and capacitance retention rate. The supercapacitor conductive modifier prepared by the method is compounded with activated carbon with a large specific surface area to prepare improved graphene supercapacitor slurry, the specific capacitance of the prepared electrode material can reach more than 110F/g by improving the proportion of the electrode material, the energy density can be increased to 100Wh/kg, and the supercapacitor with high energy density, high charge-discharge efficiency and long cycle life is prepared innovatively.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (10)
1. A preparation method of a porous graphene electrode for a supercapacitor is characterized by dispersing graphene oxide in water, and magnetically stirring to prepare a graphene oxide aqueous dispersion; adding porous graphene into the graphene oxide aqueous dispersion, and performing magnetic stirring and ultrasonic dispersion to obtain a dispersion A; adding carbon nano tubes into the dispersion liquid A, adding a binder a, homogenizing, magnetically stirring, and ultrasonically dispersing to prepare a stable dispersion liquid B; adding conductive carbon black into the stable dispersion liquid B, magnetically stirring, and ultrasonically dispersing to prepare a dispersion liquid C; adding the dispersion liquid C, the activated carbon and the binder b into deionized water for ultrasonic dispersion, stirring and oscillating in vacuum to prepare supercapacitor slurry, coating the supercapacitor slurry on the carbon-coated aluminum foil, drying the coated carbon-coated aluminum foil, and then performing vacuum drying treatment; and compacting the carbon-coated aluminum foil after vacuum drying, and then cutting into electrodes to be packaged to prepare the super capacitor.
2. The method according to claim 1, wherein the porous graphene is a high-conductivity porous graphene rapidly self-made by high-energy microwaves in a laboratory, and the microwave action time is controlled to be 10-120 s in the process of preparing the porous graphene by the microwave method; controlling the power of the microwave action of each gram of raw materials to be 200-700W; the oxidizing atmosphere is air; the purified porous graphene atmosphere is argon.
3. The method according to claim 1, wherein the mass percentages of the porous graphene, the graphene oxide and the carbon nanotubes are 70%: (1-29%): (29-1%) and the mass of the binder a accounts for 2-4% of the mass percent of the total slurry solids.
4. The method according to claim 1, wherein the conductive carbon black accounts for 1-9% of the solid mass of the slurry, and the conductive carbon black is one or a mixture of more of ultra-dense high Ks-6, Ks-15 conductive graphite, cabot XC72 conductive carbon black, Ketjen black, acetylene black, SuperP and/or SuperS.
5. The method according to claim 1, wherein the mass ratio of the modifier consisting of porous graphene, graphene oxide and carbon nanotubes to the binder a, the conductive carbon black, the activated carbon and the binder b is (1-9%): 4%: (9-1%): 80%: 6 percent and the solid content of the total slurry is 22 to 25 percent.
6. The method according to claim 1, wherein the carbon-coated aluminum foil has a thickness of 15 to 20 μm, and the electrode paste is applied to a thickness of 100 to 200 μm; the drying temperature is 70-95 ℃ for 2-3 hours, and the vacuum drying temperature is 80-100 ℃ for 8-12 hours.
7. The method of claim 1, wherein the magnetic stirring speed is 100-300 rpm/min, the ultrasonic dispersion time is 0.5-4 hours, and the ultrasonic power is 500-2000W.
8. The method of claim 1, wherein the binder a and the binder b are sodium carboxymethylcellulose, polytetrafluoroethylene, polyacrylonitrile, styrene-butadiene emulsion or aqueous polyacrylic emulsion.
9. The method according to claim 1, wherein the compaction treatment is carried out by an electric double-roller machine at a temperature of 60-80 ℃.
10. The porous graphene electrode for the supercapacitor prepared according to the method of claim 1.
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