CN107104001B - A method of adsorption of hydrolyzation polyimide molecule improves specific capacitance on the surface of graphene - Google Patents
A method of adsorption of hydrolyzation polyimide molecule improves specific capacitance on the surface of graphene Download PDFInfo
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- CN107104001B CN107104001B CN201710331766.1A CN201710331766A CN107104001B CN 107104001 B CN107104001 B CN 107104001B CN 201710331766 A CN201710331766 A CN 201710331766A CN 107104001 B CN107104001 B CN 107104001B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/13—Energy storage using capacitors
Abstract
The invention belongs to the electrode material preparation fields of the graphene-based ultracapacitor of high energy storage.The advantages that due to the big specific surface area of graphene and high electron mobility, makes graphene become a kind of ideal capacitance material.But reunite since graphene sheet layer is easy to stack, in solvent poor dispersion and oxygen-containing functional group reduction the reasons such as be not thorough, substantially reduce the practical specific capacitance of graphene.The present invention for the first time with certain mass than the uniform dispersions of liquid crystal graphene oxide/ammonium carbonate/sodium chloride/CVD graphenes directly instill in the controllable Teflon mould of size, strike off drying and forming-film, the then hydrothermal reduction in certain density ammonium hydroxide and polyimide solution, the method for then carrying out low-temperature heat prepare the nitrogen-doped graphene thin-film electrode material of high specific capacitance.The invention focus on it is extensive and it is inexpensive prepare high energy storage graphene, improve the specific capacitance and energy density of graphene-based ultracapacitor, and then promote the commercial applications of graphene-based ultracapacitor.
Description
Technical field
The present invention relates to a kind of polyimide molecules of adsorption of hydrolyzation on the surface of graphene come the method for improving specific capacitance, belongs to
In graphene-based ultracapacitor field, especially a kind of introducing fake capacitance ingredient improves the skill of Graphene electrodes specific capacitance
Art.Carbon-based supercapacitor is also referred to as electric double layer capacitance, relies on ion and is filled in the physical absorption on porous electrode surface and desorption
Electric discharge.The common high-temperature resistance plastice Kapton of industrial quarters is hydrolyzed the invention, organic small in be discharged into water
Molecule is interacted by π-π by is adsorbed to graphene surface.Such organic molecule can be with water system electricity in charge and discharge process
Reversible redox reaction occurs for solution matter.In this way, after absorption in the case of weight increase about 3% of grapheme material,
Specific capacitance incrementss reach 40%.The technical costs is low, and the large scale of graphene-based capacitor and industrialization is suitble to prepare.
Background technology
Ultracapacitor is a kind of new type of energy storage device between conventional batteries and capacitor.Although and chemical cell
Equally belong to electrochemical energy storage scope, but ultracapacitor, also referred to as electric double layer capacitance, there is fast charging and discharging, work(
Rate density is big, the advantages that having extended cycle life, is environmentally protective.These advantages are not available for ion battery, but also super capacitor
Device surpasses battery, such as the big work(for opening power supply, electric vehicle of electronic ignition device, electrically operated safety door in certain application aspects
Rate output source, etc..And one of ultracapacitor is the disadvantage is that energy density is low, therefore is inferior to electricity in the status of energy storage field
Pond.How the energy density for improving ultracapacitor by new technology is a technological challenge and the research of Material Field
Hot spot.One method is to improve the specific capacitance of electrode material, another approach is research novel electrolyte to improve voltage window.
Nowadays commercialized ultracapacitor is mainly based upon porous activated carbon, and specific capacitance has practically already been achieved the limit.
Graphene is a kind of monolayer honeycomb shape two dimension carbon nanomaterial formed in a manner of sp2 hydridization by carbon atom, is had excellent
Light, electricity, heat, physical and chemical properties.Graphene has very high specific surface area (2630m2/ g), theoretic specific capacitance is reachable
550F/g.But due to various reasons, the graphitization accumulation such as the shortcomings that material between oxygen-containing group and lamella etc. is former
Cause, the specific capacitance of the graphene ultracapacitor experimentally prepared is generally between 200-300F/g.Exploring new-type device side
Face, with graphene super capacitor it is parallel be fake capacitance ultracapacitor, electrode material can be divided into metal oxide and conduction is poly-
Close object.Theoretically such material has than graphene higher quality specific capacitance.But often resistivity is high for such material, needs
It is attached to porous conductive material surface, and when the active material carrying capacity of unit area increases, under specific capacitance can be caused notable
Drop.The voltage window of conducting polymer fake capacitance material is narrow, and cycle life is short.In general, by secondary charge and discharge cycles up to a hundred
Afterwards, the pattern of material can be substantially change.Therefore, if the organic molecule with fake capacitance property is adsorbed on graphene
Surface, increased weight is negligible, and almost each molecule can capture charge, has very high utilization ratio, then
The device is the double storage charge mechanism for being mixed with electric double layer capacitance and fake capacitance, and the advantages of the two is annexed.This will be one
Develop the effective way of high-performance super capacitor.
Invention content
This technology invention is used as fake capacitance material using the polyimides (PI) of hydrolysis for the first time, by itself and graphene combination
To prepare the ultracapacitor for having two kinds of energy storage mechnisms of electric double layer capacitance and fake capacitance concurrently.PI films hydrolyze in alkaline aqueous solution
After release amic acid small molecule, graphene surface can be attracted to by spontaneous interact by π-π.In charge and discharge
Reversible redox reaction occurs for amide acid molecule and the aqueous solution electrolysis liquid of sulfuric acid or lithium sulfate in journey, improves material
Charge storage capacity.The specific capacitance of functionalization graphene prepared by this method in dilute sulfuric acid electrolyte can reach
440F/g.Fake capacitance property retention is stable in resistance to oxidation, charge and discharge process in air and material is cheap for the PI molecules of hydrolysis
Be easy to get, environment again it is good.This technology can expand to other except graphene carbon materials as electrode of super capacitor, utilize
Simple physical absorption PI hydrolyzes molecule and improves specific capacitance.
The method comprises the steps of firstly, preparing the graphenes of nitrating.Theoretically, the specific capacitance of graphene can be improved by nitrating.Its
Principle one is to improve its quantum capacitance after nitrating, second is that N-O groups can show fake capacitance property in acidic electrolysis bath, is carried
High-capacitance.After obtaining the scraps of paper shape graphene film of N doping, it is immersed in the aqueous solution of dissolving hydrolysis PI molecules
(faint yellow), by 80 DEG C, after the heat treatment of 4h, hydrolysis PI molecules can then permeate graphene film and be attracted to carbon atomic layer
Surface.The ultracapacitor made in this way with the film can have stronger fake capacitance property, capacitance to be improved.
The present invention prepares graphene oxide with improved Hummer ' s methods, and porous and nitrating is obtained by the hydrothermal reduction method of changing
Graphene film.It is also to use to carry out in hydrothermal reaction kettle to prepare hydrolysis PI solution.It is as follows：
(1) using improved Hummer ' s methods graphene oxide is prepared using expanded graphite as raw material.It is concentrated quiet
It sets, is protected from light room temperature preservation 7~14 days, obtain liquid crystal state graphene oxide, i.e., carbon atom lamella is spontaneous due to electrostatic interaction has
Sequence arranges, and macroscopically shows the birefringent phenomenon of similar liquid crystal molecule.
(2) the liquid crystal graphene oxide of concentration about 10mg/mL is diluted to 6mg/mL with deionized water, by graphite oxide
Alkene：Ammonium carbonate (or ammonium acetate, urea)：The mass ratio of sodium chloride 1: 3: 3 prepares mixing, through magnetic agitation and ultrasonic vibration it
3~5 days are stood afterwards, obtains uniform and stable sol form solution.
(3) graphene oxide dispersion prepared is poured into the rectangular groove mould of polytetrafluoroethylene (PTFE) of 5mm depth, liquid level
It strikes off, then spontaneously dries, obtain the laminated film of uniform thickness.
(4) stripping of laminated film two panels is clamped, it is 1.5~3.5 μ l/ml to be put into equipped with 100ml ammonia concns
In the reaction kettle of (25%-28%wt ammonium hydroxide), 180 DEG C of hydrothermal reductions 3 hours, subsequent natural cooling in baking oven.
(5) hydrolysis PI solution is prepared：PI films are put into autoclave, deionized water is added, PH is adjusted with ammonium hydroxide
It is worth~11.180 DEG C of hydrolysis 3h are heated to after sealing.After reaction, obtained yellow solution is filtered, it is spare.
(6) the self-supporting graphene film obtained in step (4) is put into beaker, pour into obtained in (5) contain water
The yellow solution for solving PI molecules is heated to 80 DEG C of holding 4h, then takes out black film, be put into deionized water.
(7) graphene film after functionalization is cut into comparable size, 1M is soaked in together with porous insulation diaphragm
H2SO4In aqueous solution.It is taken out after a few hours, is assembled into the symmetric capacitor of sandwich structure, using acid metal film as afflux
Body carries out electro-chemical test.
The present invention adds nitrogenous compound (such as ammonium salt or urea) and sodium chloride in graphene oxide water solution, with
And carry out hydrothermal reduction in the aqueous solution of addition ammonium hydroxide, in order to allow graphene sheet layer undulate to be bent gauffer, subtract
Lack mutual contact area and graphitization is avoided to accumulate, while realizing nitrating.The experimental results showed that this step effect is bright
Aobvious, the specific capacitance of the graphene film of prepared loose and porous structure can reach~400F/g.We utilize the PI molecules hydrolyzed
Functionalization is carried out to the graphene film of N doping, can significantly further increase specific capacitance.This technical solution major advantage
It is：
(1) by graphene oxide and inorganic salts common distribution in aqueous solution, drying and forming-film in Teflon mold is injected, from
And obtain the presoma of Graphene electrodes.The advantages of this method be mold depth and area it is adjustable, that is, can prepare big
The graphene energy storage electrode of size and unit area high quality carrying capacity.
(2) between above-mentioned dry composite film being clipped in two sheet glass, be put into the ammonia spirit in hydrothermal reaction kettle into
Row hydrothermal reduction obtains the graphene film of loose three-dimensional structure, is used as the electrode of ultracapacitor.The advantages of the method is reduction
Method is simple and realizes N doping to graphene, obtained film self-supporting and smooth.
(3) functionalization is carried out to graphene film using the polyimides small molecule of hydrolysis, makes porous carbon electrodes table
Amide acid molecule is adsorbed in face, increases fake capacitance ingredient.This method raw material is cheap, simple for process, and in terms of improving specific capacitance
It is with obvious effects.Primary Study finds that quality and area specific capacitance can respectively reach 440F/g and 1F/cm2。
Description of the drawings
Hydrolytic Mechanism of 1 polyimides of attached drawing in alkaline aqueous solution；
The electron microscope picture of the graphene film of attached drawing 2 (a) surface adsorption water solution polyimide molecule；(b) from branch
The photo of the graphene membrane electrode of support.
The electrochemical property test of 3 ultracapacitor of attached drawing.(a) cyclic voltammetry curve compares；(b) by constant current charge and discharge
The relation curve of electric curve calculated capacitance and discharge current value.
Specific implementation mode
The present invention is further elaborated below in conjunction with example, but the invention is not limited in specific embodiments.
(1) using improved Hummer ' s methods graphene oxide is prepared using expanded graphite powder as raw material.Disperseed
After being concentrated through high speed centrifugation in deionized water, sealing and standing is protected from light room temperature preservation 7~15 days, obtains liquid crystal graphite oxide
Alkene.
(2) the liquid crystal graphene oxide viscous solution for measuring a concentration of 9.0mg/ml of 20ml is placed in 100mL beakers, then is divided
Not Jia Ru sodium chloride and ammonium carbonate, respective 588mg adds deionized water stirring and dissolving, obtains a concentration of 6mg/mL of graphene oxide
Mixed solution.Stand 3~5 days after 5 hours magnetic force stirs, obtain uniform and stable liquid crystal graphene oxide/sodium chloride/
Ammonium carbonate (or ammonium acetate, ammonium sulfate, urea) mixed dispersion liquid.
(3) the sol form mixed dispersion liquid prepared is instilled in the Teflon mould of 5mm depth, rectangular recess
Size be 4 × 8mm2, scraper is used in combination to strike off liquid level.Then mold is put into dustless cabinet and is spontaneously dried, uniform thickness is obtained
The laminated film of degree.Die depth is adjusted, the oxidation graphene film of different-thickness can be obtained after hydro-thermal.For example,
Graphene mass density is 1mg/cm2And 3.5mg/cm2Film.
(4) by the laminated film of natural drying be clipped in two panels stripping glass between, be put into the anti-of the ammonia spirit equipped with pH=11
It answers in kettle, 180 DEG C of hydrothermal reductions 3 hours, subsequent natural cooling.After reaction, the oxidation graphene film that will be obtained
It is placed in deionized water and cleans repeatedly, preserve spare in water.
(5) polyimide plastic film is put into the autoclave equipped with certain density ammonia spirit, 180 DEG C of water
Heat treatment 4 hours.Obtained yellow solution is filtered after cooling, is collected for use.
(6) graphene film after hydrothermal reduction is put into the yellow solution equipped with hydrolysis polyimides, in beaker
80 DEG C are handled 4 hours.This step is fully to adsorb the hydrolysis PI molecules being dissolved in water on the surface of graphene.After subsequent sample,
Put dilution cleaning in deionized water.
(7) film obtained in (6) is cut, the super electricity of sandwich structure is assembled into together with the porous septum of insulation
Container.Electrolyte is the H of 1M2SO4Aqueous solution carries out electro-chemical test.
The foregoing is merely the preferred embodiment of the present invention, are not intended to limit the scope of the invention, every utilization
Equivalent structure or equivalent flow shift made by present specification is applied directly or indirectly in other relevant technologies
Field is included within the scope of the present invention.
Claims (2)
1. a kind of polyimide molecule of adsorption of hydrolyzation on the surface of graphene is come the method that improves specific capacitance, which is characterized in that including
Following steps：
1) mixed solution is prepared, by the liquid crystal state graphene oxide of high concentration and nitrogen source and sodium chloride according to 1:3:3 mass ratio
Uniformly mixing in water, wherein nitrogen source are ammonium carbonate, ammonium sulfate, ammonium acetate or urea, adjust a concentration of 6mg/ of graphene oxide
ML will stand 3~5 days after solution magnetic agitation and ultrasonic vibration, obtain the mixed dispersion liquid of sol form stabilization；
2) solution drying and forming-film will prepare mixed dispersion liquid and pour into the Teflon mould of rectangular flat-bottom slot, and by liquid
Face strikes off, and then mold is put into dustless cabinet and is spontaneously dried, and obtains the laminated film of uniform thickness, adjusts die depth and ruler
It is very little, the oxidation graphene film of large scale and thickness can be prepared；
3) solid union film is subjected to hydrothermal reduction, the laminated film of natural drying is put into equipped with 100mL a concentration of 1.5~
In the reaction kettle of the ammonium hydroxide of 3.5 μ L/mL, 180 DEG C of hydrothermal reductions 3 hours, subsequent natural cooling is put into deionization after taking out film
In water；
4) polyimides is hydrolyzed, Kapton is cut into small pieces, is put into reaction kettle, the ammonia spirit of pH~11 is poured into,
180 DEG C are warming up to after sealing, high pressure hydro-thermal process 4 hours filters the yellow solution in reaction kettle after natural cooling；
5) graphene film is immersed in containing hydrolysis polyimide molecule by the polyimide molecule of adsorption of hydrolyzation on the surface of graphene
Yellow solution in, 80 DEG C holding 4h, then graphene film is taken out, impregnate in deionized water, dilution cleaning.
2. a kind of polyimide molecule of adsorption of hydrolyzation on the surface of graphene according to claim 1 improves the side of specific capacitance
Method, which is characterized in that graphene film is immersed in the aqueous solution containing hydrolysis polyimide molecule, under the conditions of 70-100 DEG C
It is sufficiently mixed, then graphene film is cleaned with deionized water, remove solute extra in solution, this method utilizes object
Reason absorption, it is easy to operate, after adsorbing organic functional molecular on the surface of graphene, the total weight increase by 3% of electrode, but specific capacitance
Incrementss be more than 30%.
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| CN201710331766.1A CN107104001B (en) | 2017-05-12 | 2017-05-12 | A method of adsorption of hydrolyzation polyimide molecule improves specific capacitance on the surface of graphene |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107706007A (en) * | 2017-10-13 | 2018-02-16 | 北京航空航天大学 | A kind of aquo-lithium ion ultracapacitor based on graphene and organic molecule |
| CN110358141B (en) * | 2019-07-09 | 2022-04-15 | 兰州大学 | Preparation method of flame-retardant high polymer material |
| CN114420465B (en) * | 2021-12-17 | 2023-08-18 | 武夷学院 | Preparation method of graphene-based electrode |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104658770A (en) * | 2014-12-22 | 2015-05-27 | 西北师范大学 | Preparation method of methyl green-modified reduced graphene oxide and application of methyl green-modified reduced graphene oxide as supercapacitor electrode material |
| CN106449180A (en) * | 2016-11-28 | 2017-02-22 | 北京航空航天大学 | Method for increasing specific capacitance of graphene-based supercapacitor |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104658770A (en) * | 2014-12-22 | 2015-05-27 | 西北师范大学 | Preparation method of methyl green-modified reduced graphene oxide and application of methyl green-modified reduced graphene oxide as supercapacitor electrode material |
| CN106449180A (en) * | 2016-11-28 | 2017-02-22 | 北京航空航天大学 | Method for increasing specific capacitance of graphene-based supercapacitor |
Non-Patent Citations (2)
| Title |
|---|
| Harnessing Three Dimensional Anatomy of Graphene Foam to Induce Superior Damping in Hierarchical Polyimide Nanostructures;Pranjal Nautiyal等;《Small》;20161130;第13卷;第1603473-1-8页 * |
| Three-dimensional graphene/polyimide composite-derived flexible high-performance organic cathode for rechargeable lithium and sodium batteries;Yanshan Huang等;《Journal of Materials Chemistry A》;20170104;第5卷;第2710–2716页 * |
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