WO2014190772A1 - Graphene, graphene electrode, graphene super capacitor and preparation method thereof - Google Patents

Abstract

Disclosed are a graphene, a graphene electrode, a graphene super capacitor and preparation methods thereof. The preparation method of the graphene comprises the following steps: a) prereducing graphite oxide; b) setting the prereduced graphite oxide on a substrate; and c) laser-reducing the substrate having the graphite oxide set thereon to form graphene. According to the preparation method of graphene in the embodiment of the present invention, the prereduced graphite oxide can be reduced more easily into graphene via laser-reducing, since the graphite oxide has been prereduced in a certain degree prior to the laser reduction (namely, full reduction). The reducing effect of graphene obtained from the prereduced graphite oxide film after one photoetching is evidently superior to that of the graphene prepared without prereduction treatment. Therefore, the time of laser reduction can be apparently decreased and the production efficiency can be improved in the present invention.

Description

Technical field

 The present invention relates to the field of preparation of electronic components, and more particularly to the technical field of preparation of graphene, graphene electrodes and graphene supercapacitors. Background technique

 Energy is the foundation of human survival. As petrochemical energy is depleted, the energy crisis has become a problem faced by countries in the world today. The sustainable development of the global economy and society is facing severe challenges. The energy crisis includes the storage, conversion, transmission of energy and the development of energetic materials. Among them, energy storage plays an important role in human development.

 With the improvement of people's living standards, the continuous development and utilization of green energy has become a hot spot of concern. Among them, supercapacitors are new types of green energy storage devices. The energy density is dozens of times that of traditional capacitors. The power density is hundreds of times that of batteries. The charging and discharging efficiency is about 15% higher than that of batteries. The development of supercapacitor is super successful. The development of energy storage equipment has brought new hope.

Graphene is a carbon molecule in which carbon atoms are arranged in a hexagonal shape and connected to each other, and the structure thereof is very stable. Graphene has high conductivity, high toughness, high strength and large specific surface area. The single-layer graphene has a specific surface area of 2630 m ² /g, which is an ideal supercapacitor energy storage material.

Conventional preparation methods of graphene include: mechanical stripping method, chemical reduction method, microwave assisted method, chemical vapor deposition method, and the like. However, these methods face such problems in actual mass production: high energy consumption, high cost, and difficulty in mass production. Summary of the invention The present invention is directed to solving at least some of the above technical problems or at least providing a useful commercial choice.

 In view of the above, the present invention needs to provide a graphene and a preparation method thereof, which are simple in preparation process and are advantageous for improving production efficiency.

 In addition, the present invention also needs to provide a graphene electrode and a preparation method thereof, and the method for preparing the graphene electrode has a simple process and high production efficiency.

 The present invention also needs to provide a graphene supercapacitor and a preparation method thereof, and the preparation process of the graphene supercapacitor is simple, efficient, and low in cost.

 A method for producing graphene according to an embodiment of the first aspect of the present invention, comprising the steps of: a) pre-reducing graphite oxide; b) disposing said graphite oxide after pre-reduction treatment on a substrate; and c) The substrate provided with graphite oxide is subjected to laser reduction to form the graphene.

 According to the method for producing graphene of the above embodiment, the graphite oxide after the pre-reduction still maintains the characteristics of graphite oxide (high resistance, insulation), and thus can also be used as a separator of a micro supercapacitor; meanwhile, due to laser reduction ( That is, a certain degree of pre-reduction is performed before the high-reduction), and the graphite oxide after the pre-reduction is more easily reduced to graphene by laser reduction. After the pre-return of the graphite oxide film, the reduction effect after one-time recording is significantly better than that of the graphite oxide without pre-reduction treatment. Therefore, the present invention can significantly shorten the time of laser reduction and improve production efficiency.

 Further, the method for producing graphene according to the above embodiment of the present invention may further have the following additional technical features:

 In some embodiments of the present invention, the step a) comprises: disposing the graphite oxide in an aqueous solution of a pre-reducing agent to form a mixed liquid to perform a pre-reduction treatment on the graphite oxide.

In some embodiments of the invention, the mass ratio of the pre-reducing agent to the graphite oxide in the mixed liquid is a pre-reducing agent: graphite oxide = 0.1 to 0.75. In some embodiments of the invention, the pre-reducing agent comprises any one or a combination of vitamin C, hydrazine hydrate, sodium borohydride.

 In some embodiments of the present invention, the mixed solution further contains a dispersing agent, and the dispersing agent comprises a selected from the group consisting of a modified polytetrafluoroethylene emulsion, a polyvinyl alcohol solution, and N,N-dimethylformamide. Any one or a combination thereof, and the mass ratio of the dispersant to the graphite oxide is 0.005 to 0.03.

 In some embodiments of the invention, the mixture is dispersed for 2 to 10 minutes using ultrasonic dispersion. In some embodiments of the invention, the step b) comprises: coating the mixed solution on the substrate, the substrate being polyethylene terephthalate, aluminum foil, silicon wafer, poly Any of dimethyl siloxane, modified polydimethylsiloxane, polyvinylidene fluoride, or polytetrafluoroethylene.

 In some embodiments of the present invention, the step c) includes: pasting and compacting the substrate provided with the graphite oxide on the illumination surface of the optical engraving optical disc, and then placing the optical disc into the light irradiation recorder, and using The infrared laser is irradiated.

 Graphene according to an embodiment of the second aspect of the present invention is produced by a method for producing a graphene according to an embodiment of the first aspect of the present invention.

 A method for producing a graphene electrode according to an embodiment of the third aspect of the present invention includes the steps of: processing graphene obtained by the method for producing graphene according to the embodiment of the first aspect of the present invention into interdigitated, parallel strip, spiral Any of the shapes and their combined shapes to obtain the graphene electrode.

 In some embodiments of the invention, a collector is attached to the graphene.

 In some embodiments of the present invention, a conductive tape is attached to one side of the graphene as the collector, and the conductive tape includes a copper tape, a copper foil or an aluminum foil with an adhesive, and any of the conductive cloth. One.

A graphene electrode according to an embodiment of the fourth aspect of the present invention is produced by a method for producing a graphene electrode according to an embodiment of the third aspect of the present invention. A method for preparing a graphene supercapacitor according to an embodiment of the fifth aspect of the present invention, comprising the steps of: encapsulating a graphene electrode obtained by the method for preparing a graphene electrode according to an embodiment of the third aspect of the present invention, and pouring an electrolyte solution, to be After drying, packaging is performed to obtain the graphene supercapacitor.

 In some embodiments of the present invention, the graphene electrode is encapsulated by an encapsulating tape comprising any one of a Kapton tape, a scotch tape, a sealing tape, a stationery tape, and an insulating tape.

 In some embodiments of the invention, the electrolyte solution comprises a polyvinyl alcohol/sulfuric acid system, a polyvinyl alcohol/phosphoric acid system, a polymethyl methacrylate-ethylene carbonate-lithium perchlorate system, and a polyoxyethylene-poly polymer. Ethylene glycol-trifluoromethanesulfonate system, polyaniline-1-ethyl-3-methylimidazolium tetrafluoroborate-trimethylsilanol system, 1-butyl-3-methylimidazolium Trifluoromethylsulfonyl phthalimide-smoke silica gel system, 1-butyl-3-methylimidazolium tetrafluoroborate-smoke silica gel system.

 A graphene supercapacitor according to an embodiment of the sixth aspect of the present invention is produced according to the method for producing a graphene supercapacitor according to the fifth aspect of the present invention.

 In some embodiments of the invention, the graphene electrodes are oxidized graphite that has not been subjected to laser reduction to isolate the graphene electrodes as spacers.

 The additional aspects and advantages of the invention will be set forth in part in the description which follows. DRAWINGS

 The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from

1 is a process flow diagram of a method of preparing graphene according to an embodiment of the present invention; 2 is a schematic view showing the appearance of a graphene electrode according to Embodiment 1 of the present invention;

 Figure 3 is a perspective view showing the structure of a graphene supercapacitor according to Embodiment 2 of the present invention; and Figure 4 is a graph showing the charge and discharge curves of a graphene supercapacitor according to Embodiment 2 of the present invention. detailed description

 Embodiments of the present invention are described in detail below. The embodiments described below with reference to the drawings are intended to be illustrative of the invention and are not to be construed as limiting.

 Hereinafter, a method of preparing graphene according to an embodiment of the present invention will be described first with reference to FIG.

 As shown in FIG. 1, a method for preparing graphene according to an embodiment of the present invention includes the following steps: Step a): pre-reducing graphite oxide

 As a method of pre-reducing the graphite oxide, for example, laser reduction, chemical reduction, or the like can be employed.

 In some embodiments of the invention, the graphite oxide is added to an aqueous solution of a pre-reducing agent (for example, a solution configured with deionized water) to form a mixed liquid to pre-reductively treat the graphite oxide.

 Here, the graphite oxide may be introduced in the form of a commercially available aqueous dispersion of graphite oxide, and of course, it may be a powder prepared according to a conventional production method.

 The amount of the pre-reducing agent is designed according to the amount of the graphite oxide. For example, the mass ratio of the pre-reducing agent to the graphite oxide may be a pre-reducing agent: graphite oxide = 0.1 to 0.75. By setting the amount of the pre-reducing agent and the amount of the graphite oxide in this range, not only the intended pre-reduction effect can be achieved, but also excessive reaction by-products remain in the final product (ie, graphene), thereby improving The production efficiency ensures the electrical properties of graphene as a product.

The pre-reducing agent is not particularly limited as long as the graphite oxide can be reduced. For example, any one of vitamins, hydrazine hydrate, sodium borohydride or a mixture thereof can be used. Further, in order to uniformly disperse the graphite oxide in the mixed liquid, thereby improving the film forming effect, a graphene film having a smooth and uniform surface can be obtained after being disposed on the substrate, and the mixture can be obtained in the mixed liquid. Further add a suitable dispersant.

 The kind of the dispersant is not particularly limited, and examples thereof include a modified polytetrafluoroethylene emulsion, a polyvinyl alcohol solution, hydrazine, hydrazine-dimethylformamide, and the like, and a mixture thereof. Regarding the content of the dispersant, the mass ratio with respect to the graphite oxide may be 0.005 to 0.03.

 In order to further improve the dispersion effect, the mixed solution was also dispersed by ultrasonic dispersion for 2 to 10 minutes.

 Step b): disposing the graphite oxide after the pre-reduction treatment on the substrate

 Next, the graphite oxide after the pre-reduction treatment is placed on the substrate. As a method of setting, for example, a mixed liquid containing pretreated graphite oxide may be coated on a substrate, a substrate may be immersed in the above mixed liquid, and the mixed liquid droplet may be applied onto a substrate or the like.

 According to an embodiment of the present invention, from the viewpoint of improving the uniformity of the formed graphene film, it is preferred to apply the mixed solution on the substrate.

 The substrate is not particularly limited, and may be, for example, polyethylene terephthalate (abbreviated as

PET), aluminum foil, silicon wafer, polydimethylsiloxane (referred to as PDMS), modified polydimethylsiloxane, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) .

 Step c): performing laser reduction on the substrate provided with graphite oxide to form the graphene after the pre-reduced graphite oxide is disposed on the substrate, in order to further reduce the graphite oxide to obtain Graphene requires laser reduction of a substrate provided with graphite oxide.

 In some embodiments of the present invention, the step C) includes: pasting and compacting the substrate provided with the graphite oxide on the illumination surface of the optical engraving optical disc, and placing the light into the light-emitting recorder, with a predetermined schedule wavelength

An infrared laser (for example, 780 nm) is irradiated. At this time, the substrate is adhered and compacted on the irradiated surface of the optical disc for optical engraving, thereby avoiding friction between the substrate and the inner tray surface of the engraving machine during the irradiation.

 Here, it should be noted that, in the laser reduction process, a predetermined shape (for example, an interdigitated shape, a parallel strip shape, a spiral shape, and the like may be designed and formed through a predetermined program (for example, software, an ASIC dedicated circuit, or the like). The graphene of any one of the combined shapes, at this time, the formed graphene can be directly used as an electrode. Of course, it is also possible to form a large sheet of graphene by laser reduction, and thereafter, by cutting, to form a graphene electrode of a desired shape. That is, the graphene of the first aspect of the present invention can also be directly used as a graphene electrode according to the specific process design in the light irradiation process and the specific requirements of the capacitor used.

 According to the method for preparing graphene according to the embodiment of the present invention, for the first time, by the pre-reduction of the pre-reducing agent, the production efficiency of the graphene used for preparing the electrode is effectively improved, and the desired pattern can be realized by one-time irradiation.

 It should be noted that the graphene obtained by the above process can be directly used as the graphene electrolysis, or can be processed into an interdigitated shape, a parallel strip shape, a spiral shape or the like as a graphene electrode according to actual needs. Forming the graphene electrode into any one of an interdigitated shape, a parallel strip shape, a spiral shape, and a combination thereof can eliminate the diaphragm structure in the conventional graphene supercapacitor, thereby making the preparation process simple and efficient, and cost low.

 Further, after obtaining a graphene electrode having a predetermined shape, in order to improve the electrical properties of the graphene electrode, a collector may be connected to the graphene. In some embodiments of the present invention, a conductive tape is attached to one side of the graphene as a collector, and the conductive tape includes a copper tape, a copper foil or an aluminum foil with an adhesive, and any of the conductive cloth. One.

 A method of preparing a graphene supercapacitor according to an embodiment of the present invention is described below.

A method for preparing a graphene supercapacitor according to an embodiment of the present invention can be obtained as described above The graphene electrode is packaged and cast with an electrolyte solution, and after being dried, it is completely packaged to obtain a graphene supercapacitor.

 Specifically, the graphene electrode encapsulating tape may be packaged during laser reduction, and the encapsulating tape may be any of Kapton tape, scotch tape, sealing tape, stationery tape, and insulating tape.

 Wherein, the electrolyte solution may be an electrolyte solution generally used in a graphene supercapacitor, such as a polyvinyl alcohol/sulfuric acid system, a polyvinyl alcohol/phosphoric acid system, a polymethyl methacrylate-ethylene carbonate-lithium perchlorate system. , polyoxyethylene-polyethylene glycol-trifluoromethanesulfonic acid lithium system, polyaniline-1-ethyl-3-methylimidazolium tetrafluoroborate-trimethylsilanol system, 1-butyl- 3-methylimidazolium bistrifluoromethylsulfonylimide-smoke silica gel system, 1-butyl-3-methylimidazolium tetrafluoroborate-smoke silica gel system.

 Next, a method of preparing a graphene electrode according to the present invention will be further described by way of specific examples.

 Raw materials:

 I) Graphite oxide:

 Brand: Charcoal TM Sinocarbon

 Production unit: Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences

 Model: 5mg/ml, 100ml/bottle.

 II) Pre-reducing agent-vitamin C (ascorbic acid):

 Brand: single crystal card;

Specification: Analytical grade, 25g/bottle, C ₆ H ₈ 0 ₆ content not less than 99.7%;

 Production unit: Tianjin Chemical Reagent Research Institute

 III) Dispersant - PTFE Emulsion:

Brand: HLLD Yi Lida Specifications: ADL-301, resin content 58%~62%, particle size 0.05~0.16, PH value 7~9 Production unit: Xinxiang Yelida Power Material Co., Ltd. Example 1

 First, graphite oxide is added to an aqueous solution of vitamin C (pre-reducing agent) to prepare a mixed solution. Among them, in the mixed solution, the mass ratio of vitamin C to graphite oxide is 1:3. And add 2wt ^ PTFE emulsion (dispersant) to graphite oxide.

 Next, the mixture was ultrasonically dispersed for 2 minutes, and the mixture was applied to a PET film having a thickness of 180 μm, and naturally dried at room temperature for 15 hours.

 Thereafter, according to the following steps, laser reduction is performed to form graphene having an interdigitated appearance shape.

1. Install Nero software on the working machine.

 2. The shape of the graphene electrode is designed to be interdigitated by Nero Cover Designer software (as shown in Figure 2, Al and A2 represent positive and negative graphene electrodes respectively), and the illumination parameters such as gray scale and print contrast are set.

 3. Paste the substrate with the pre-reduced graphite oxide on the label surface of the special light-engraving disc, and place the label face down on the optical drive with lightscribe to be printed.

 4. Select the pattern of the appearance shape of the designed graphene electrode in the above two items, place it in the area to be printed, and start laser reduction.

5. After the irradiation is completed, the optical disc drive is ejected to remove the light engraving disc, and the graphene electrode obtained by the light irradiation is taken out.

 Thereby, the graphene electrode 1 was obtained.

It should be noted that, in the present embodiment, although the above-described software is used to design the appearance shape of the graphene electrode, the present invention is not limited thereto, and an appearance shape capable of forming a desired graphene electrode can be used. Any way to handle it.

 Comparative example 1

 The graphene electrode 2 was produced in the same manner except that the pre-reduction treatment was not carried out.

 By comparing the graphene electrode 1 and the graphene electrode 2 described above, it is known that the graphite oxide solution which has not been subjected to the pre-reduction treatment is more difficult to be irradiated into a complete interdigital or other electrode after drying, and the light irradiation effect is poor, and it is almost impossible. Experiment to test its performance.

 On the other hand, according to the graphene electrode 1 of the embodiment 1 of the present invention, since the pre-reduction treatment is performed, the light-shaving effect is good, and a complete pattern (the shape of the electrode) can be formed by one cycle of irradiation, and the number of times of recording increases. The better the electrical properties of the graphene electrode, the lower the resistance. However, after more than 10 recordings, there is no obvious change. Therefore, the number of burns is generally controlled from 1 to 6 times. Example 2

 Next, a graphene supercapacitor 100 according to Embodiment 2 of the present invention will be described with reference to Figs. 2 to 4 . As shown in FIG. 3, the graphene supercapacitor 100 includes: a casing (not shown); a graphene electrode LSG (ie, the graphene electrode 1 obtained in Embodiment 1); collectors M1, M2; a package E, and an electrolyte Solution (not shown).

 Wherein, the substrate of the graphene electrode LSG is a PET film (P shown in the figure); the collectors M1 and M2 are copper tapes, which are collectors of the graphene electrode LSG; the graphene electrode LSG is the graphene obtained in the embodiment 1. The electrode 1, which is formed in an interdigitated shape, the graphite graphite B between the positive and negative graphene electrodes Al and A2 of the interdigitated shape naturally isolates the electrodes in space (as shown in FIG. 2), thereby omitting the separator of the conventional supercapacitor component.

K shown in Fig. 3 is a kapton tape, which fixes and encapsulates the graphene electrode LSG. The package E is an upper cover of the capacitor and is fixed to the casing by a double-sided tape. As the electrolyte solution of the graphene supercapacitor, a PVA/H2S04 electrolyte solution was used. 4 shows charge and discharge curves of a single graphene supercapacitor prepared according to Embodiment 2 of the present invention, wherein, for a graphene electrode A1 and a negative graphite electrode A2 as shown in FIG. 2, 1OX10 mm of graphene is formed. The supercapacitor 100 has a charge and discharge voltage window of 0 to 0.9 V, a charge and discharge current of 15 uA, and the capacity of the graphene supercapacitor 100 is calculated according to a discharge curve by the following formula:

C=It/U=15*10- 6*99/0.9=1.65X10- ³ F

On the other hand, the calculated effective interdigital area of a single electrode was 22.5 mm ² . Therefore, it can be understood that the specific capacitance of the graphene supercapacitor 100 obtained according to the second embodiment is converted into the area ratio capacitance:

C,=C/S=1.65X10- ³ /(22.5*10- ⁶ )=73.3F/m ²

 As can be seen from the above, the graphene supercapacitor 100 according to the present invention has the advantages of simple structure, good electrical performance, simple preparation process, low cost, and the like, and can be widely used for new energy vehicles, sensor energy storage devices, and the like.

 In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the invention. In the present specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

 Although the embodiments of the present invention have been shown and described, it is understood that the foregoing embodiments are illustrative and not restrictive Variations, modifications, alterations and variations of the above-described embodiments are possible within the scope of the invention.

Claims

claims 1. A method for preparing graphene, characterized by comprising the following steps: a) Pre-reduction treatment of graphite oxide; b) disposing the pre-reduced graphite oxide on the substrate; and c) Perform laser reduction on the substrate provided with graphite oxide to form the graphene. 2. The method for preparing graphene according to claim 1, characterized in that step a) includes: adding the graphite oxide to an aqueous solution of a pre-reducing agent to form a mixed liquid, so as to perform the pre-reducing process on the graphite oxide. Pre-restore processing. 3. The method for preparing graphene according to claim 2, characterized in that the mass ratio of the pre-reducing agent to the graphite oxide in the mixed liquid is pre-reducing agent: graphite oxide =0.1~0.75. 4. The method for preparing graphene according to claim 3, wherein the pre-reducing agent includes any one of vitamin C, hydrazine hydrate, sodium borohydride or a combination thereof. 5. The method for preparing graphene according to claim 2, wherein the mixed liquid also contains a dispersant, and the dispersant is selected from the group consisting of modified polytetrafluoroethylene emulsion, polyvinyl alcohol solution, N , any one of N-dimethylformamide or a combination thereof, and the mass ratio of the dispersant to the graphite oxide is 0.005~0.03. 6. The method for preparing graphene according to claim 2, characterized in that the mixed liquid is dispersed for 2 to 10 minutes using ultrasonic dispersion. 7. The method for preparing graphene according to any one of claims 2 to 6, wherein step b) includes: coating the mixed liquid on the substrate, and the substrate It is any one of polyethylene terephthalate, aluminum foil, silicon wafer, polydimethylsiloxane, modified polydimethylsiloxane, polyvinylidene fluoride, or polytetrafluoroethylene. 8. The method for preparing graphene according to claim 1, characterized in that, step c) It includes: pasting and compacting a substrate provided with graphite oxide on the irradiation surface of a light engraving optical disc, then placing the optical disc into a light irradiation recorder, and irradiating it with an infrared laser with a predetermined wavelength. 9. Graphene, characterized in that it is prepared according to the preparation method of graphene according to any one of claims 1 to 8. 10. A method for preparing a graphene electrode, characterized by comprising the following steps: processing the graphene obtained according to the method for preparing graphene according to claims 1 to 8 into an interdigitated shape, a parallel strip shape, or a spiral shape Any one of its combined shapes to obtain the graphene electrode. 11. The method for preparing a graphene electrode according to claim 10, characterized in that a collector is connected to the graphene. 12. The method for preparing a graphene electrode according to claim 11, wherein a conductive tape is pasted on one side of the graphene as the collector, and the conductive tape includes a copper tape and an adhesive. Any of copper foil, aluminum foil, or conductive cloth. 13. A graphene electrode, characterized in that it is prepared by the preparation method of a graphene electrode according to any one of claims 10 to 12. 14. A method for preparing a graphene supercapacitor, characterized by comprising the following steps: packaging the graphene electrode obtained according to the method for preparing a graphene electrode according to claims 10 to 12 and pouring an electrolyte solution, and after drying Encapsulation is performed to obtain the graphene supercapacitor. 15. The method for preparing a graphene supercapacitor according to claim 14, wherein the graphene electrode is packaged by packaging tape, and the packaging tape includes Kapton tape, transparent tape, sealing tape, stationery tape, Any type of insulating tape. 16. The method for preparing a graphene supercapacitor according to claim 14, wherein the electrolyte solution includes a polyvinyl alcohol/sulfuric acid system, a polyvinyl alcohol/phosphoric acid system, and polymethyl methacrylate-ethylene carbonate. -Lithium perchlorate system, polyethylene oxide-polyethylene glycol-lithium triflate system, Polyaniline-1-ethyl-3-methylimidazole tetrafluoroborate-trimethylsilanol system, 1-butyl-3-methylimidazole bistrifluoromethylsulfonyl imide-smoked silica gel system, 1-butyl-3-methylimidazole tetrafluoroborate-smoked silica gel system. 17. A graphene supercapacitor, characterized in that it is prepared by the preparation method of a graphene supercapacitor described in any one of claims 14 to 16. 18. The graphene supercapacitor according to claim 17, wherein graphene oxide that has not been reduced by laser is used as an isolation member to isolate the graphene electrodes between the graphene electrodes.