• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Procedure for obtaining a flexible electrode. The present invention relates to a method of obtaining a flexible graphene oxide electrode comprising a step of placing transparent material in visible light between both faces of the flexible graphene oxide material prior to irradiation with visible light. The electrode obtained by this procedure is capable of being used in supercapacitors. Therefore, the present invention can be framed in the area of energy. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2734729A1
    申请号:ES201830553
    申请日:2018-06-07
    公开日:2019-12-11
    发明作者:Del Pino Angel Perez；Valladares Alex Ygnacio Chuquitarqui；Liviu Cosmin Cotet
    申请人:Consejo Superior de Investigaciones Cientificas CSIC；BABES BOLYAI, University of；
    IPC主号:
    专利说明:

    [0001]
    [0002] Procedure for obtaining a flexible electrode
    [0003]
    [0004] The present invention relates to a process for obtaining a flexible graphene oxide electrode comprising a step of placing transparent light-visible material on both sides of the flexible graphene oxide material prior to irradiation with visible light. The electrode obtained by this procedure is capable of being used in supercapacitors.
    [0005]
    [0006] Therefore, the present invention can be framed in the area of energy.
    [0007]
    [0008] BACKGROUND OF THE INVENTION
    [0009]
    [0010] Supercapacitors are electrochemical devices capable of storing and discharging a large amount of electrical energy at very high rates, presenting much higher charge-discharge powers than batteries. The supercapacitors are formed by pairs of electrodes separated by a sheet called separator that is impregnated with electrolyte.
    [0011]
    [0012] For a few years there has been a great interest in the development of graphene-based electrodes due to their great electrical conductivity, excellent mechanical properties and large effective surface, which would potentially allow the production of supercapacitors of very high performance. In light of the technical and economic difficulties of graphene, the use of graphene oxide (GO) is being extended with its subsequent reduction to obtain a structure with properties similar to graphene.
    [0013]
    [0014] Lately, there is a particular interest in the development of mechanically flexible supercapacitors to be used in mobile devices and ultra-thin portable electronic devices.
    [0015]
    [0016] The document “Graphene oxide prepared by graphene nanoplatelets and reduced by laser treatment 'Nanotechnology 2017 Jun 2; 28 ( 22): 224002 from Longo A, Verucchi R, Aversa L, Tatti R, Ambrose A, Orabona E, Coscia U, Carotenuto G, Maddalena P. refers to the preparation of a graphene sheet based on an aqueous solution that It is applied on a polymeric PET substrate and then subjected to drying. A laser beam of Nd: YVO4 is applied to said layer within the range of the visible (532 nm). In this way the GO is reduced to rGO following patterns that remain in the flexible substrate. Laminar resistance measurements that indicate an effective increase in electrical conductivity are 2.9 KQsq-1.
    [0017]
    [0018] The document “Optimizing the optical and electrical properties of graphene ink thin films by laser-annealing '' 2015, 2D Materials 2 011003 by Sepideh Khandan Del, Rainer Bornemann, Andreas Bablich, Heiko Schafer-Eberwein, Jiantong Li, Torsten Kowald, Mikael Ostling Peter Haring Bolívar and Max C Lemme discloses a procedure in which a graphene ink stabilized with a polymer is applied which is applied to a glass sheet by controlled dripping. After drying, the substrate with the tank is subjected to annealing at 400 ° C for 30 min, to remove the polymer. The reduction is carried out with a laser beam in the visible range (green CW DPSS laser 532 nm, 500 mW, Fa. CNI).
    [0019]
    [0020] The document “Tunable graphene oxide reduction and graphene patterning at room temperature on arbitrary substrates” Carbon Volume 109, November 2016, Pages 173 181 of Ning-Qin Deng, He Tian, Zhen-Yi Ju, Hai-Ming Zhao, Cheng Li, Mohammad Ali Mohammad, Lu-Qi Tao, Yu Pang, Xue-Feng Wang, Tian-Yu Zhang, Yi Yang, Tian-Ling Ren describes how to prepare a dispersion of GO that is uniformly deposited on a glass substrate where it is allowed to dry . A visible laser is applied on this tank (LD-F650G03 max 200 and 650 nm).
    [0021]
    [0022] These documents do not mention measures to prevent the re-oxidation of manufactured graphene-based electrodes, a fact that directly affects the final properties of supercapacitors, so it is necessary to develop procedures aimed at obtaining more stable graphene-based electrodes.
    [0023] DESCRIPTION OF THE INVENTION
    [0024]
    [0025] The present invention relates to a process for obtaining a flexible electrode that can be used in a supercapacitor. The procedure is environmentally sustainable and easily scalable at the industrial level.
    [0026]
    [0027] In a first aspect, the present invention relates to a method of obtaining a flexible electrode (from here "the process of the invention"), characterized in that it comprises the following steps:
    [0028] a) preparing a flexible graphene oxide membrane or a flexible graphene oxide-polymer substrate assembly,
    [0029] b) placing a sheet of transparent material in visible light of wavelength between 450 nm and 750 nm on both sides of the membrane or of the assembly obtained in step (a) to form an oxidized graphene-transparent material system, and
    [0030] c) irradiating the system obtained in step (b) with visible laser light of wavelength between 450 nm and 750 nm.
    [0031]
    [0032] All steps of the process of the invention are preferably carried out at room temperature.
    [0033]
    [0034] In a preferred embodiment of step (a) of the process of the invention, the flexible graphene oxide membrane of step (a) has been prepared by deposition or controlled pouring of an aqueous dispersion of graphene oxide onto a substrate, by For example, a glass substrate, followed by drying the graphene oxide sheet that forms on said substrate and the subsequent separation of said graphene oxide sheet from the substrate.
    [0035]
    [0036] In another more preferred embodiment of step (a) of the process of the invention, the flexible graphene oxide-polymer substrate set of step (a) has been obtained by deposition or controlled pouring of a graphene oxide dispersion onto a substrate. flexible polymer. Step (a) is carried out at room temperature by pouring the dispersion of graphene oxide onto the flexible polymeric substrate, thus ensuring the integrity of the polymeric substrate, i.e. prevents degradation of the polymer since it is operated at room temperature.
    [0037]
    [0038] Examples of flexible polymeric substrate are a substrate of polyethylene terephthalate (PET), polycarbonate (PC) and polydimethylsiloxane (PDMS).
    [0039]
    [0040] Step (b) of the process of the invention seeks to place a sheet of transparent material in visible light of wavelength between 450 nm and 750 nm on both sides of the graphene oxide membrane or of the graphene oxide substrate substrate flexible polymer obtained in step (a), to form a transparent grafenomaterial oxide system.
    [0041]
    [0042] The sheet of the transparent material should not have structural defects to ensure good mechanical contact with the graphene oxide membrane or with the flexible graphene oxide-polymer substrate assembly of step (a).
    [0043]
    [0044] An example of a sheet of material transparent to visible light is a glass sheet or a transparent thermoplastic such as polyethylene.
    [0045]
    [0046] Step (c) of the process of the present invention refers to the irradiation of the system obtained in step (b) with visible light of wavelength between 450 nm and 750 nm. Step (c) of the process of the invention is intended to reduce the graphene oxide of the graphene oxide membrane or flexible polymeric graphene substrate substrate of step (a) by irradiation with visible light of wavelength between 450 nm and 750 nm.
    [0047]
    [0048] Irradiation at a wavelength in the range of the visible is an advantage over irradiation with a wavelength corresponding to the infrared range since it corresponds to a higher energy per photon. Therefore, irradiating with visible light causes a greater chemical reactivity in graphene oxide.
    [0049]
    [0050] The function of the sheet of material transparent to visible light at this stage is to limit the reabsorption of oxygen, in other words, to prevent the reoxidation of reduced graphene oxide, which is an advantage for the stability and durability of the susceptible flexible electrode if used in a supercapacitor.
    [0051] The irradiated zone is converted into reduced graphene oxide (rGO), while the non-irradiated zone (from here "remainder material") remains intact as graphene oxide. It should be noted that the remaining material can be easily removed by immersion in water.This is an advantage when designing electrodes with different patterns.
    [0052]
    [0053] Irradiation in step (c) can be carried out with irradiation lamps or with laser systems. Preferably, the irradiation of step (c) is carried out with laser systems.
    [0054]
    [0055] A "laser system" is a device that emits light through optical amplification and by stimulating the emission of electromagnetic radiation. The word "Laser" comes from the acronym for Light Amplification by Stimulated Emission of Radiation which means light amplified by stimulated radiation emission. It is a device that uses induced or stimulated emission to generate a coherent beam of light both spatially and temporarily. Spatial coherence corresponds to the ability of a beam to remain small in size when transmitted by vacuum over long distances and temporal coherence is related to the ability to concentrate the emission over a very narrow spectral range.
    [0056]
    [0057] The laser system of the present invention operates in the spectral range of the visible, specifically in a wavelength range between 450 nm and 750 nm. It is a laser system that emits light continuously, although pulsed lasers that emit short duration pulses could be used by adjusting parameters such as creep (J / cm2) and the laser pulse emission frequency (Hz).
    [0058]
    [0059] In a preferred embodiment of the process of the invention, the irradiation of step (c) is carried out with a continuous laser system operating in the range of the visible at wavelengths between 450 nm and 750 nm, preferably laser light Visible wavelength of 450 nm or 532 nm .. For the wavelength of 450 nm good results are obtained when the power is around 1.5 W and the laser beam is focused on areas from 0.25 to 0 , 5 mm in diameter.
    [0060]
    [0061] Throughout the description and claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or Steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention.
    [0062]
    [0063] BRIEF DESCRIPTION OF THE FIGURES
    [0064]
    [0065] FIG. 1 Thermal simulation of an irradiated system with a laser beam of 250 pm in diameter and a scanning speed of 200 mm / min.
    [0066]
    [0067] FIG. 2 Laminar resistance as a function of irradiation time for samples 1 and 2 of GO (II) and sample 1 of GO (I). Samples 1 and 2 were manufactured with 0.1 mm and 0.2 mm of separation between consecutive pixels, respectively.
    [0068]
    [0069] FIG. 3 Absorbance spectra in infrared spectroscopy (FTIR) of a sheet of graphene oxide GO (I) (sample 1) before and after irradiating with laser.
    [0070]
    [0071] FIG. 4 Variation of surface capacitance with voltage scan speed. Insertion: cyclic voltammetries at different scanning rates for sample 2 of GO (II).
    [0072]
    [0073] FIG.5 Retention of the electrochemical capacity with cycling of a flexible microcondenser type GO (II) -sample 2 manufactured on PET, measured with chronopotentiometry. Insertion: Voltage cycles obtained with a current of 100 pA and an optical microscopy image of the microcondenser (interdigital type).
    [0074]
    [0075] EXAMPLES
    [0076]
    [0077] Next, the invention will be illustrated by tests carried out by the inventors, which demonstrates the effectiveness of the product of the invention.
    [0078]
    [0079] First, several equal samples are prepared for two variants (I and II) of graphene oxide dispersions (GO):
    [0080] • GO type (I): aqueous dispersion of GO synthesized according to J. Mater. Chem. A, 2017, 5, 2132 of LV Cotet et al
    [0081] • GO type (II): 2.5% by weight dispersion of commercial GO (Nanoinnova Technologies SL) in glacial acetic acid (Panreac).
    [0082]
    [0083] The dispersions are stirred 30 min and sonicated 15 min before being poured onto a surface of polyethylene terephthalate (PET) and allowed to dry.
    [0084]
    [0085] The type (I) dispersion can also be deposited on a glass sheet and, after drying, be removed in the form of a stable flexible membrane.
    [0086]
    [0087] It has been calculated that a spillage of 0.4 g / cm2 of dispersion produces a GO layer of about 0.1 mm thickness after drying.
    [0088]
    [0089] Next, the polymeric GO-substrate set or the GO membrane is positioned tightly between two sheets of glass, that is to say a glass sheet on both sides of the polymeric GO-substrate or GO membrane assembly. Subsequently, it is irradiated with a continuous laser beam of 450 nm wavelength and 1.5 W of power. The laser beam focuses on areas of 0.25 to 0.5 mm in diameter. The samples are manufactured by scanning the laser spot at constant speed (parallel traces), as well as by irradiating consecutive pixels with a given exposure time. The best results are obtained with 0.1 mm and 0.2 mm distance between consecutive pixels (samples 1, 2).
    [0090]
    [0091] The irradiation process causes an increase in the temperature of the GO by several hundred degrees Celsius and its consequent deoxidation, resulting in its chemical transformation to reduced GO. The glass top sheet does not absorb the laser radiation, it is transparent to visible light, it also makes it difficult to re-enter oxygen, which prevents the reoxidation and pyrolysis of the GO during its processing, the GO would burn and evaporate without these glass sheets .
    [0092]
    [0093] The thermal cycle depends on the size of the laser spot and its scanning speed (or, equivalently, the exposure time in pixel irradiation). A thermal simulation of an irradiated system with a laser beam of 250 pm in diameter and a scanning speed of 200 mm / min is shown in Fig. 1 a value of 500 ° C.
    [0094]
    [0095] The functional properties of the electrodes were characterized by:
    [0096] • Sheet resistance: The sheet resistance was studied using the van der Pauw method, using a double source-meter system (Keithley 2612B) and a micropuntas station (PRCBE mini from Perfic Lab).
    [0097] • Cyclic voltammetry and chronopotentiometry: Electrochemical properties were studied using a Keithley 2450-EC system equipped with a special electrochemical cell for flat electrodes (Bio-Logic).
    [0098]
    [0099] Fig. 2 shows the sheet resistance of electrodes manufactured by the proposed method as a function of the irradiation time per pixel. The laminar resistance value varies depending on the type of graphene oxide used, as well as the experimental irradiation conditions: laser intensity, separation between consecutive pixels and irradiation time. However, there is a common feature: the resistance value decreases with increasing irradiation time.
    [0100]
    [0101] As can be seen in Fig. 2, the present invention achieves less than 10 Q / sq with irradiation, the minimum value obtained so far is 6 Q / sq. This result indicates that the electrodes of the present invention are likely to be used in supercapacitors.
    [0102]
    [0103] Comparison with the prior art:
    [0104]
    [0105] Resistance values of the order of 100 Q / sq [K. have been found in the literature . Griffiths et al Nanoscale 2014, 6, 13613-13622] for similar systems irradiated with a single pulse of infrared light. This value is insufficient to obtain good performance supercapacitors.
    [0106]
    [0107] In Fig. 3 a significant decrease of the FTIR absorption bands related to chemical groups containing oxygen can be observed when a GO layer is irradiated, and the variation of the sheet resistance from 3 MQ / sq to only 7.7 Q / sq. Also, the temperature increase experienced by the GO layer causes the polymer surface at the GO-substrate interface to partially melt. and interact with the GO layer, resulting in a great adhesion of it to the substrate.
    [0108]
    [0109] It should be noted that, after irradiation, the non-irradiated GO can simply be removed by immersion in water. In this way, the non-irradiated GO is released, dispersed in the water and can be reused.
    [0110]
    [0111] In order to carry out the measurements of the surface capacitance of the electrodes by cyclic voltammetry, an aqueous electrolyte of Na2SO41 M has been used. stretched rectangle, without additional reduction-oxidation peaks on the horizontal sides of the rectangle, and capacitance values per unit area, equivalent to dividing the electrode's capacity between its surface, greater than 100 mF / cm2.
    [0112]
    [0113] Comparison with the prior art:
    [0114]
    [0115] The maximum values identified in the literature are in the range of 10 mF / cm2 [P.Yadav et al Adv. Mater. Interfaces 2016, 3, 1600057].
    [0116]
    [0117] The surface capacitance values were obtained from the cyclic voltammetry measurements, the type GO (II) being the one that offers the highest capacitance values (> 100 mF / cm2 in sweeps at 10 mV / s).
    [0118]
    [0119] Cycling tests using chronopotentiometry indicate that devices manufactured using this technique can maintain performance for at least hundreds of voltage cycles (Fig. 5).
    权利要求:
    Claims (6)
    [1]
    1. A procedure for obtaining a flexible electrode, characterized in that it comprises the following steps:
    a) preparing a flexible graphene oxide membrane or a flexible graphene oxide-polymer substrate assembly,
    b) placing a sheet of transparent material in visible light of wavelength between 450 nm and 750 nm on both sides of the membrane or of the assembly obtained in step (a) to form a graphene oxide-transparent material system, and
    c) irradiate the system obtained in step (b) with visible light of wavelength between 450 nm and 750 nm.
    [2]
    2. The process according to claim 1, wherein the flexible graphene oxide membrane of step (a) has been prepared by deposition of an aqueous graphene oxide dispersion on a substrate and subsequently separated from the substrate.
    [3]
    3. The process according to claim 1, wherein the flexible polymeric graphene substrate substrate of step (a) has been obtained by deposition of a dispersion of graphene oxide on a flexible polymeric substrate.
    [4]
    4. The process according to claim 3, wherein the composition of the polymeric flexible substrate is selected from polyethylene terephthalate, polycarbonate and polydimethylsiloxane.
    [5]
    5. The method according to any of claims 1 to 4, wherein, in step (c), a continuous laser system is used.
    [6]
    6. The method according to claim 5, wherein, in step (c) visible laser light of wavelength of 450 nm or 532 nm is used.
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    同族专利:
    公开号 | 公开日
    WO2019234284A1|2019-12-12|
    ES2734729B2|2020-04-23|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2014190772A1|2013-05-30|2014-12-04|纳米新能源（唐山）有限责任公司|Graphene, graphene electrode, graphene super capacitor and preparation method thereof|
    WO2016066889A1|2014-10-30|2016-05-06|Nokia Technologies Oy|A method of forming a graphene oxide-reduced graphene oxide junction|
    WO2018039710A1|2016-08-30|2018-03-08|Swinburne University Of Technology|Capacitors, electrodes, reduced graphene oxide and methods and apparatuses of manufacture|
    法律状态:
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    优先权:
    申请号 | 申请日 | 专利标题
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    PCT/ES2019/070394| WO2019234284A1|2018-06-07|2019-06-07|Method for obtaining a flexible electrode|
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