CN112086297B - Graphene nanocarbon electrode material, preparation method and lithium ion capacitor electrode - Google Patents
Graphene nanocarbon electrode material, preparation method and lithium ion capacitor electrode Download PDFInfo
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Abstract
The invention discloses a graphene nanocarbon electrode material, a preparation method and a lithium ion capacitor electrode, wherein the preparation method comprises the following steps: carrying out ultrasonic mixing on graphene oxide and a nano-carbon material in a solvent according to a preset mass ratio to obtain a uniformly mixed dispersion liquid with a preset concentration, adding hydrogen peroxide into the uniformly mixed dispersion liquid, stirring and dispersing uniformly, irradiating with ultraviolet rays under the stirring condition to obtain a mixture solution, and carrying out pore-forming on a graphene oxide sheet layer through ultraviolet rays and a hydrogen peroxide system to prepare porous graphene oxide, wherein the effect is obvious and the environment is protected; and (2) freeze-drying the mixture solution, reducing the solid substance obtained by freeze-drying by microwave radiation with different powers to obtain the graphene nanocarbon electrode material, and reducing by microwave, wherein the reduction degree is high, the time consumption is short, the energy consumption is extremely low, and the method is simple, convenient and fast, simple and convenient in equipment, low in cost and suitable for large-scale industrial production.
Description
Technical Field
The invention relates to the technical field of energy, in particular to a graphene nanocarbon electrode material, a preparation method and a lithium ion capacitor electrode.
Background
With the development of society, the demand for energy sources is increasing, and the demand for energy storage devices is also increasing. In particular withWith the consumption of fossil energy and the rise of electric automobiles, new requirements are put forward on energy storage devices. The lithium ion capacitor is used as a combination of the lithium ion battery and the super capacitor, and has the ultrahigh energy density of the lithium ion battery and the ultrahigh power density and the ultra-long cycle life of the super capacitor. The requirements on the next generation of energy storage devices are well met. The electrode material has been the focus of research as the core of energy storage devices. For example, the silicon in the anode material has a height of 4200mAh g-1But are difficult to be put into practical use due to volume expansion exceeding 300%, low conductivity and cycle life of less than 100 cycles, and other oxide electrodes suffer from these problems. The current commercial graphite negative electrode has good stability, but also has the problem of low capacity, and the theoretical capacity is 372mAh g-1. Therefore, it is very urgent to develop a negative electrode material with high stability and high capacity. Most of the anode materials of Lithium Ion Capacitors (LIC) are activated carbon, and the commercial LIC anode is mainly commercial activated carbon at present. Although the commercial activated carbon has good stability and long cycle life, the characteristic of low capacity is very outstanding, and the capacity is 30-45 mAh g-1This can greatly limit the overall energy density of the LIC.
Graphene has many advantages as a new material in carbon materials. Meanwhile, the method has excellent performance in the field of energy storage, and occupies an important position in the field of battery electrodes and the field of super capacitor electrodes. The existing reduction method for reducing graphene oxide mainly comprises the following steps: high temperature reduction, solvothermal, chemical reduction, and the like. These methods have the disadvantages of long time consumption, large energy consumption, incomplete reduction, high equipment requirement and unsuitability for large-scale industrial production.
Therefore, how to provide an electrode material with excellent electrochemical performance, short time consumption, low energy consumption, low equipment requirement and suitability for large-scale industrial production is a technical problem to be solved urgently.
Disclosure of Invention
The invention mainly aims to provide a graphene nanocarbon electrode material, a preparation method and a lithium ion capacitor electrode, and aims to solve the technical problems that the preparation process of the electrode material in the prior art is long in time consumption, large in energy consumption, incomplete in reduction, high in equipment requirement, unsuitable for large-scale industrial production and poor in electrochemical performance.
In order to achieve the above object, the present invention provides a method for preparing a graphene nanocarbon electrode material, comprising the following steps:
carrying out ultrasonic mixing on graphene oxide and a nano carbon material in a solvent according to a preset mass ratio to obtain a uniformly mixed dispersion liquid with a preset concentration;
adding hydrogen peroxide into the uniformly mixed dispersion liquid, and irradiating by using ultraviolet rays under the stirring condition to obtain a mixture solution;
and (3) freeze-drying the mixture solution, and reducing the solid substance obtained by freeze-drying by microwave radiation with different powers to obtain the graphene nano-carbon electrode material.
Preferably, the preset mass ratio is 1: (0-1), wherein the solvent is an aqueous solution or an ethanol solution, and the preset concentration is 1 mg/ml-2 mg/ml.
Preferably, the step of adding hydrogen peroxide to the uniformly mixed dispersion liquid and irradiating with ultraviolet rays under a stirring condition to obtain a mixture solution includes:
adding 1-20mL of hydrogen peroxide with the concentration of 10% -30% into the uniformly mixed dispersion under the condition of magnetic stirring, and irradiating for 0.5-10 hours by using ultraviolet rays while stirring to obtain a mixture solution.
Preferably, the step of adding hydrogen peroxide to the uniformly mixed dispersion liquid and irradiating with ultraviolet rays under a stirring condition to obtain a mixture solution includes:
adding 1-20mL of hydrogen peroxide with the concentration of 10% -30% into the uniformly mixed dispersion under the condition of mechanical stirring, and irradiating for 0.5-10 hours by using ultraviolet rays while stirring to obtain a mixture solution.
Preferably, the step of freeze-drying the mixture solution and subjecting the solid substance obtained by freeze-drying to reduction treatment by microwave radiation with different powers to obtain the graphene nanocarbon electrode material comprises:
and (3) freeze-drying the mixture solution at 0 ℃ for 36 hours, and reducing the solid matter obtained by freeze-drying for 1-60 seconds by microwave radiation with different powers to obtain the graphene nanocarbon electrode material.
Preferably, the graphene oxide is prepared by a modified hummers method; the nano carbon material comprises at least one of activated carbon, conductive carbon black, carbon nano tubes, fullerene, carbon quantum dots and graphene quantum dots.
Preferably, the ultraviolet light is generated by an ultraviolet lamp, and the power of the ultraviolet lamp is 4-100W; the power of the microwave is 500-1000W.
Preferably, after the step of performing freeze drying on the mixture solution, and performing reduction treatment on the solid substance obtained by freeze drying by microwave radiation with different powers to obtain the graphene nanocarbon electrode material, the method further comprises:
and (3) mixing the graphene nanocarbon electrode material, the conductive carbon black and the polyvinylidene fluoride according to the following ratio of (7-9): (1-0.5): (2-0.5) preparing the mixture into slurry;
and coating the slurry on a carbon-coated aluminum foil, and drying at 80 ℃ for 10-20 hours to obtain the electrode.
In addition, in order to achieve the above purpose, the present invention further provides a graphene nanocarbon electrode material, which is prepared according to the above preparation method of the graphene nanocarbon electrode material.
In addition, in order to achieve the above purpose, the present invention also provides a lithium ion capacitor electrode, in which the graphene nanocarbon electrode material described above is used as a positive electrode and/or a negative electrode of the lithium ion capacitor electrode.
The invention at least comprises the following beneficial effects:
in the invention, graphene oxide and a nano-carbon material are ultrasonically mixed in a solvent according to a preset mass ratio to obtain a uniformly mixed dispersion liquid with a preset concentration. Adding hydrogen peroxide into the uniformly mixed dispersion liquid under the condition of magnetic stirring, irradiating by using ultraviolet rays to obtain a mixture solution, forming pores by using an ultraviolet ray and hydrogen peroxide system as materials, and utilizing the hydrogen peroxide to generate free radicals in a solvent to attack defect sites on the graphene oxide nano-carbon composite material, so that a large number of microporous structures generated on graphene oxide lamella and interlayer ion channels constructed by the CNT among the lamellae are constructed to construct three-dimensional ion channels, and the energy provided by ultraviolet irradiation can promote the rapid generation of the free radicals, shorten the pore-forming process, and has obvious effect and environmental protection; and (3) freeze-drying the mixture solution, and reducing the solid substance obtained by freeze-drying by microwave radiation with different powers to obtain the graphene nano-carbon electrode material. For the graphene nano-carbon electrode material, nano-carbon is used as a conductive connector between graphene sheets to construct a three-dimensional conductive network channel, and meanwhile, the nano-carbon is used as a structural support between graphene sheets to prevent graphene from being stacked again; the nano carbon is also used as a graphene oxide microwave reduction initiator to initiate reduction reaction. The microwave is adopted for reduction treatment, the reduction degree is high, the time consumption is short, the energy consumption is extremely low, the high-quality reduced graphene oxide nano carbon compound can be quickly reduced in a short time, and the method is simple, convenient, simple and convenient to implement, simple and convenient in equipment, low in cost and suitable for large-scale industrial production.
Drawings
Fig. 1 is a schematic flow chart of a first embodiment of a method for preparing a graphene nanocarbon electrode material according to the present invention;
fig. 2 is a scanning photograph of the graphene nanocarbon electrode material obtained in example 2;
fig. 3 is a graph comparing the adsorption and desorption curves of example 2 and comparative example 2.
Detailed Description
The present invention is further described in detail below with reference to the drawings and examples so that those skilled in the art can practice the invention with reference to the description.
It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.
Referring to fig. 1, fig. 1 is a schematic flow chart of a first embodiment of a method for preparing a graphene nanocarbon electrode material according to the present invention, and proposes the first embodiment of the method for preparing the graphene nanocarbon electrode material according to the present invention.
In a first embodiment, the preparation method of the graphene nanocarbon electrode material comprises the following steps:
and step S10, ultrasonically mixing the graphene oxide and the nano-carbon material in a solvent according to a preset mass ratio to obtain a uniformly mixed dispersion liquid with a preset concentration.
It is understood that the preset mass ratio is 1: (0-1), wherein the solvent is an aqueous solution or an ethanol solution, and the preset concentration is 1 mg/ml-2 mg/ml. For example, the graphene oxide and the nanocarbon material may be mixed in a mass ratio of 1: (0-1) ultrasonic mixing is carried out in 200mL of aqueous solution or ethanol solution.
And step S20, adding hydrogen peroxide into the uniformly mixed dispersion liquid, and irradiating by using ultraviolet rays under the stirring condition to obtain a mixture solution.
The stirring conditions include magnetic stirring conditions, mechanical stirring conditions, ultrasonic mixing with an ultrasonic mixer under 200-600W power, and other stirring methods, which are not limited in this embodiment. Usually, 1-20mL of hydrogen peroxide (H) is added to the uniformly mixed dispersion under magnetic stirring202) Said H is202The concentration is usually 10% to 30%, preferably, 1 to 20mL of 30% H is added202And irradiating the mixture with ultraviolet rays for 0.5 to 10 hours while stirring to obtain a mixture solution. Or adding 1-20mL of hydrogen peroxide with the concentration of 10% -30% into the uniformly mixed dispersion under the condition of mechanical stirring, and irradiating for 0.5-10 hours by using ultraviolet rays while stirring to obtain a mixture solution. And adding 1-20mL of hydrogen peroxide with the concentration of 10% -30% into the uniformly mixed dispersion liquid, and irradiating the mixture for 0.5-10 hours by using ultraviolet rays while performing ultrasonic mixing by using an ultrasonic mixer under the power of 200-600W to obtain a mixture solution.
And step S30, freeze-drying the mixture solution, and reducing the solid matter obtained by freeze-drying by microwave radiation with different powers to obtain the graphene nanocarbon electrode material.
It should be understood that the mixture solution obtained by the treatment is freeze-dried, and the solid matter obtained by freeze-drying is put into a microwave oven to be reduced for 1-60 seconds(s) by microwave radiation with different powers, so as to obtain the reduced porous graphene oxide nanocarbon composite electrode material, i.e. the graphene nanocarbon electrode material.
In this embodiment, graphene oxide and a nanocarbon material are ultrasonically mixed in a solvent according to a preset mass ratio to obtain a uniformly mixed dispersion liquid with a preset concentration. Adding hydrogen peroxide into the uniformly mixed dispersion liquid under the condition of magnetic stirring, irradiating by using ultraviolet rays to obtain a mixture solution, forming pores by using an ultraviolet ray and hydrogen peroxide system as materials, and utilizing the hydrogen peroxide to generate free radicals in a solvent to attack defect sites on the graphene oxide nano-carbon composite material, so that a large number of microporous structures generated on graphene oxide lamella and interlayer ion channels constructed by the CNT among the lamellae are constructed to construct three-dimensional ion channels, and the energy provided by ultraviolet irradiation can promote the rapid generation of the free radicals, shorten the pore-forming process, and has obvious effect and environmental protection; and (3) freeze-drying the mixture solution, and reducing the solid substance obtained by freeze-drying by microwave radiation with different powers to obtain the graphene nano-carbon electrode material. For the graphene nano-carbon electrode material, nano-carbon is used as a conductive connector between graphene sheets to construct a three-dimensional conductive network channel, and meanwhile, the nano-carbon is used as a structural support between graphene sheets to prevent graphene from being stacked again; the nano carbon is also used as a graphene oxide microwave reduction initiator to initiate reduction reaction. The microwave is adopted for reduction treatment, the reduction degree is high, the time consumption is short, the energy consumption is extremely low, the high-quality reduced graphene oxide nano carbon compound can be quickly reduced in a short time, and the method is simple, convenient, simple and convenient to implement, simple and convenient in equipment, low in cost and suitable for large-scale industrial production.
With reference to fig. 1, a second embodiment of the method for preparing the graphene nanocarbon electrode material according to the present invention is provided based on the first embodiment of the method.
In this embodiment, the step S20 includes:
adding 1-20mL of hydrogen peroxide with the concentration of 10% -30% into the uniformly mixed dispersion under the condition of magnetic stirring, and irradiating for 0.5-10 hours by using ultraviolet rays while stirring to obtain a mixture solution.
The step S30 includes:
and (3) freeze-drying the mixture solution at 0 ℃ for 36 hours, and reducing the solid matter obtained by freeze-drying for 1-60 seconds by microwave radiation with different powers to obtain the graphene nanocarbon electrode material.
Further, in this embodiment, the graphene oxide is prepared by a modified hummers method; the nano carbon material comprises at least one of activated carbon, conductive carbon black, carbon nano tubes, fullerene, carbon quantum dots and graphene quantum dots.
It is understood that the graphene oxide is prepared by a modified hummers method, and the graphene oxide is obtained by intercalating graphite powder with acid and an oxidant under mild conditions, washing metal and inorganic ions in the graphite powder with diluted hydrochloric acid, filtering, drying and performing high-temperature treatment. The acid is one or a mixture of more of concentrated sulfuric acid, concentrated nitric acid, phosphoric acid and perchloric acid. For example, mixing graphite powder with acid, slowly adding an oxidant into an ice bath, reacting in the ice bath for 2-48 hours after uniform mixing, heating to 35 ℃, continuously oxidizing for 36-120 hours, diluting with water, and adding hydrogen peroxide to obtain a mixed aqueous solution containing graphite oxide; B. vacuum filtering the mixed aqueous solution containing graphite oxide, washing with dilute hydrochloric acid with the volume concentration of 10%, washing residual metal ions and inorganic ions with dilute hydrochloric acid with the volume concentration of 0.5-1%, filtering, and drying to obtain a filter cake; C. and (3) crushing the filter cake, and treating at high temperature for 15-30 seconds to obtain the graphene oxide.
Further, the ultraviolet rays are generated by an ultraviolet lamp, and the power of the ultraviolet lamp is 4-100W; the power of the microwave is 500-1000W.
Preferably, the nanocarbon material is Carbon Nanotubes (CNTs, abbreviated as CNT).
Preferably, the ultraviolet irradiation time is 2 hours, and the power of the ultraviolet lamp is 8W.
Preferably, the microwave time of the microwave is 20 s.
Preferably, the power of the microwave is 700W.
After the step S30, the method further includes:
and (3) mixing the graphene nanocarbon electrode material, the conductive carbon black and the polyvinylidene fluoride according to the following ratio of (7-9): (1-0.5): (2-0.5) preparing the mixture into slurry;
and coating the slurry on a carbon-coated aluminum foil, and drying at 80 ℃ for 10-20 hours to obtain the electrode.
In specific implementation, the obtained graphene nanocarbon electrode material, conductive carbon black and polyvinylidene fluoride (poly (vinylidenefluoride), abbreviated as PVDF) are prepared according to the following formula (7-9): (1-0.5): (2-0.5) (e.g., 8: 1: 1) in a mass ratio, coating the slurry on a carbon-coated aluminum foil, and drying at 80 ℃ for 10-20 hours (e.g., 12 hours) to obtain an electrode. The prepared electrode can be used as the anode or the cathode of a lithium ion capacitor, and can also be used for the anode and the cathode of the lithium ion capacitor.
In this embodiment, for a graphene nanocarbon electrode material, nanocarbon is used as a conductive connector between graphene sheets and forms a three-dimensional conductive network channel together with a pore structure on the graphene sheets; meanwhile, the nano carbon is used as a structural support between graphene layers to prevent graphene from being stacked again, and the nano carbon is also used as an initiator for reducing graphene oxide by microwave radiation to initiate a reduction reaction; by means of H202And ultraviolet ray system to make microporous structure on the composite material of graphene oxide/nano carbon by using H202Free radicals can be generated in aqueous solution or ethanol solution to attack defect sites on the graphene oxide/nano-carbon composite material, so that a large number of ion channels penetrating through a graphene plane are constructed by the principle of a microporous structure, and energy provided by ultraviolet irradiationThe amount can promote the generation of free radicals quickly, and the pore-forming process is shortened; the reduced graphene oxide/nano-carbon composite prepared by the microwave reduction method has the characteristics of high efficiency, convenience, energy conservation, environmental friendliness and large-scale industrial production, and can be quickly reduced in a short time to obtain a high-quality reduced graphene oxide nano-carbon composite, namely the graphene nano-carbon electrode material.
The technical solutions of the present invention are further described in detail below with reference to specific examples and drawings, it should be understood that the following examples are merely illustrative of the present invention and are not intended to limit the present invention.
Example 1:
200mg of graphene oxide and 12.5mg of CNT are dissolved in 200mL of aqueous solution or ethanol solution, and are uniformly mixed by ultrasonic treatment at 600W for 30 minutes. To the resulting well-mixed dispersion was added 3mL of 30% H2O2The mixture was magnetically stirred for 2 hours under 8W of UV irradiation. And (3) freeze-drying the obtained solution to obtain a mixed solid of porous graphene oxide and CNT, putting the mixed solid into a microwave oven, and performing microwave for 20s at the power of 700W to obtain a final product, namely the reduced porous graphene oxide/CNT composite electrode material, namely the graphene nano carbon electrode material.
Example 2:
200mg of graphene oxide and 12.5mg of CNT are dissolved in 200mL of aqueous solution or ethanol solution, and are uniformly mixed by ultrasonic treatment at 600W for 30 minutes. To the resulting well-mixed dispersion was added 5mL of 30% H2O2The mixture was magnetically stirred for 2 hours under 8W UV irradiation. And (3) freeze-drying the obtained solution to obtain a mixed solid of porous graphene oxide and CNT, putting the mixed solid into a microwave oven, and performing microwave for 20s at the power of 700W to obtain a final product, namely the reduced porous graphene oxide/CNT composite electrode material, namely the graphene nano carbon electrode material.
As shown in fig. 2, fig. 2 is a scanning photograph of the graphene nanocarbon electrode material obtained in example 2.
Example 3:
200mg of graphene oxide and 12.5mg of CNT are dissolved in 200mL of aqueous solution or ethanol solution, and ultrasonic treatment is carried out at a power of 600WMix well for 30 minutes. To the resulting well-mixed dispersion was added 7mL of 30% H2O2The mixture was magnetically stirred for 2 hours under 8W UV irradiation. And (3) freeze-drying the obtained solution to obtain a mixed solid of porous graphene oxide and CNT, putting the mixed solid into a microwave oven, and performing microwave for 20s at the power of 700W to obtain a final product, namely the reduced porous graphene oxide/CNT composite electrode material, namely the graphene nano carbon electrode material.
Example 4:
200mg of graphene oxide is dissolved in 200mL of aqueous solution or ethanol solution, and is uniformly mixed by ultrasonic for 30 minutes at the power of 600W. To the resulting well-mixed dispersion was added 1mL of 10% H2O2The mixture was magnetically stirred for 0.5 hour under 4W of UV irradiation. And freeze-drying the obtained solution to obtain a mixed solid of porous graphene oxide and CNT, putting the mixed solid into a microwave oven, and performing microwave treatment for 1s at the power of 500W to obtain a final product, namely the reduced porous graphene oxide/CNT composite electrode material, namely the graphene nano carbon electrode material.
Example 5:
200mg of graphene oxide and 200mg of CNT are dissolved in 200mL of aqueous solution or ethanol solution, and are uniformly mixed by ultrasonic treatment at 600W for 30 minutes. To the resulting well-mixed dispersion was added 20mL of 30% H2O2The mixture was magnetically stirred for 10 hours under 100W of UV irradiation. And (3) freeze-drying the obtained solution to obtain a mixed solid of porous graphene oxide and CNT, putting the mixed solid into a microwave oven, and performing microwave treatment for 60s at the power of 1000W to obtain a final product, namely the reduced porous graphene oxide/CNT composite electrode material, namely the graphene nano carbon electrode material.
Comparative example 1:
200mg of graphene oxide is dissolved in 200mL of aqueous solution or ethanol solution, and is uniformly mixed by ultrasonic for 30 minutes at the power of 600W. To the resulting well-mixed dispersion was added 5mL of 30% H2O2The mixture was magnetically stirred for 2 hours under 8W UV irradiation. Freeze-drying the obtained solution to obtain a mixed solid of porous graphene oxide and CNT, putting the mixed solid into a microwave oven, and performing microwave for 20s at the power of 700W to obtain a final product, namely the reduced porous graphene oxide/CNT compositeAnd (3) synthesizing an electrode material, namely the graphene nanocarbon electrode material.
Comparative example 2:
200mg of graphene oxide and 12.5mg of CNT are dissolved in 200mL of aqueous solution or ethanol solution, and are uniformly mixed by ultrasonic treatment at 600W for 30 minutes. And (3) freeze-drying the obtained solution to obtain a mixed solid of porous graphene oxide and CNT, putting the mixed solid into a microwave oven, and performing microwave for 20s at the power of 700W to obtain a final product, namely the reduced porous graphene oxide/CNT composite electrode material, namely the graphene nano carbon electrode material. As shown in fig. 3, fig. 3 is a graph comparing the absorption and desorption curves of example 2 and comparative example 2, and the abscissa represents the Relative Pressure (Relative Pressure) and the ordinate represents the amount of adsorption (Quantity Adsorbed), and it is understood that the pore formation by the ultraviolet ray and the hydrogen peroxide system in example 2 is more effective, the specific surface area of the graphene nanocarbon electrode material can be increased, and the amount of adsorption is more excellent.
Comparative example 3:
200mg of graphene oxide and 200mg of CNT are dissolved in 200mL of aqueous solution or ethanol solution, and are uniformly mixed by ultrasonic treatment at 600W for 30 minutes. To the resulting well-mixed dispersion was added 5mL of 30% H2O2The mixture was magnetically stirred for 2 hours under 8W UV irradiation. And (3) freeze-drying the obtained solution to obtain a mixed solid of porous graphene oxide and CNT, putting the mixed solid into a microwave oven, and performing microwave for 20s at the power of 700W to obtain a final product, namely the reduced porous graphene oxide/CNT composite electrode material, namely the graphene nano carbon electrode material.
Table 1 table of properties of graphene nanocarbon electrode materials obtained in each example
It can be seen from the above examples and comparative examples that different amounts of hydrogen peroxide have a large influence on the capacity of the final electrode material as positive and negative electrodes, wherein 5ml of hydrogen peroxide is most suitable. And researches find that the hydrogen peroxide-ultraviolet irradiation hole treatment also obviously improves the capacity of the final anode and cathode. The effect obtained by taking single graphene oxide as a raw material to perform hydrogen peroxide-ultraviolet irradiation hole treatment is not ideal, which shows that the CNT plays a very important role in the material, but the dosage of the CNT is also a very important parameter, and the final capacity is reduced due to the fact that the content of too much or too little CNT is high. Compared with the prior art, the method is simple, almost has no pollution, has high efficiency, is suitable for large-scale production, and has the performance far higher than that of most reported technologies. The characteristics of the anode and the cathode can be simultaneously used, so that the complex processes in the material preparation process can be greatly reduced, the matching property between the anode and the cathode materials can be improved, and the power density and the energy density can be improved more easily.
The invention also provides a graphene nanocarbon electrode material prepared by the preparation method of the graphene nanocarbon electrode material. Since the graphene nanocarbon electrode material adopts all technical solutions of all the embodiments, the graphene nanocarbon electrode material at least has the beneficial effects brought by the technical solutions of the embodiments, and details are not repeated herein.
The invention also provides a lithium ion capacitor electrode, and the graphene nano carbon electrode material is used as the positive electrode and/or the negative electrode of the lithium ion capacitor electrode.
The prepared graphene nanocarbon electrode material can be used for a positive electrode or a negative electrode of a lithium ion capacitor, and can also be used for the positive electrode and the negative electrode of the lithium ion capacitor. When used as the anode of a lithium ion capacitor, the electrolyte is 0.1A g-1Can reach 112mAh g under the current density-1The capacity of (a); 5A g-1More than 10000 cycles of the circulating capacity is kept to 96% of the initial capacity. When used for the negative electrode, is 0.1A g-1Can reach 1250mAh g under the current density-1The capacity of (a); 2A g-1The capacity of the battery is kept above 95% when the current exceeds 1000 circles, and the capacity of the battery assembled by the positive electrode and the negative electrode can reach 230Wh kg-1High specific energy density.
In this example, a reduced porous graphene oxide nanocarbon composite electrode materialThe graphene nanocarbon electrode material shows excellent capacity characteristics, cycle performance and ultrahigh rate performance when being applied to the positive electrode and the negative electrode of a lithium ion capacitor. The total battery assembled by the positive electrode and the negative electrode can reach 230Wh kg-1High specific energy density.
Since the lithium ion capacitor electrode adopts all technical solutions of all the embodiments, the lithium ion capacitor electrode at least has the beneficial effects brought by the technical solutions of the embodiments, and details are not repeated herein.
While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable to various fields of endeavor for which the invention may be embodied with additional modifications as would be readily apparent to those skilled in the art, and the invention is therefore not limited to the details shown and described herein without departing from the generic concept as defined by the claims and their equivalents.
Claims (9)
1. A preparation method of a graphene nanocarbon electrode material is characterized by comprising the following steps:
carrying out ultrasonic mixing on graphene oxide and a nano carbon material in a solvent according to a preset mass ratio to obtain a uniformly mixed dispersion liquid with a preset concentration; wherein the preset mass ratio is 1: (0-1), wherein the solvent is an aqueous solution or an ethanol solution, and the preset concentration is 1 mg/ml-2 mg/ml;
adding hydrogen peroxide into the uniformly mixed dispersion liquid, and irradiating by using ultraviolet rays under the stirring condition to obtain a mixture solution;
and (3) freeze-drying the mixture solution, and reducing the solid substance obtained by freeze-drying by microwave radiation with different powers to obtain the graphene nano-carbon electrode material.
2. The method for preparing the graphene nanocarbon electrode material according to claim 1, wherein the step of adding hydrogen peroxide to the uniformly mixed dispersion liquid and irradiating the mixture with ultraviolet rays under stirring conditions to obtain a mixture solution comprises:
adding 1-20mL of hydrogen peroxide with the concentration of 10% -30% into the uniformly mixed dispersion under the condition of magnetic stirring, and irradiating for 0.5-10 hours by using ultraviolet rays while stirring to obtain a mixture solution.
3. The method for preparing the graphene nanocarbon electrode material according to claim 1, wherein the step of adding hydrogen peroxide to the uniformly mixed dispersion liquid and irradiating the mixture with ultraviolet rays under stirring conditions to obtain a mixture solution comprises:
adding 1-20mL of hydrogen peroxide with the concentration of 10% -30% into the uniformly mixed dispersion under the condition of mechanical stirring, and irradiating for 0.5-10 hours by using ultraviolet rays while stirring to obtain a mixture solution.
4. The method for preparing the graphene nanocarbon electrode material according to claim 1, wherein the step of freeze-drying the mixture solution and subjecting the freeze-dried solid substance to reduction treatment by microwave radiation of different powers to obtain the graphene nanocarbon electrode material comprises:
and (3) freeze-drying the mixture solution at 0 ℃ for 36 hours, and reducing the solid matter obtained by freeze-drying for 1-60 seconds by microwave radiation with different powers to obtain the graphene nanocarbon electrode material.
5. The method for preparing the graphene nanocarbon electrode material according to claim 1, wherein the graphene oxide is prepared by a modified hummers method; the nano carbon material comprises at least one of activated carbon, conductive carbon black, carbon nano tubes, fullerene, carbon quantum dots and graphene quantum dots.
6. The method for preparing the graphene nanocarbon electrode material according to claim 1, wherein the ultraviolet light is generated by an ultraviolet lamp, and the power of the ultraviolet lamp is 4 to 100W; the power of the microwave is 500-1000W.
7. The method for preparing the graphene nanocarbon electrode material according to any one of claims 1 to 6, wherein the step of freeze-drying the mixture solution and reducing the freeze-dried solid substance with microwave radiation of different powers to obtain the graphene nanocarbon electrode material further comprises:
and (3) mixing the graphene nanocarbon electrode material, the conductive carbon black and the polyvinylidene fluoride according to the following ratio of (7-9): (1-0.5): (2-0.5) preparing the mixture into slurry;
and coating the slurry on a carbon-coated aluminum foil, and drying at 80 ℃ for 10-20 hours to obtain the electrode.
8. A graphene nanocarbon electrode material, which is prepared by the method for preparing a graphene nanocarbon electrode material according to any one of claims 1 to 7.
9. A lithium ion capacitor electrode, characterized in that the graphene nanocarbon electrode material according to claim 8 is used as a positive electrode and/or a negative electrode of a lithium ion capacitor.
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