Method for preparing a supercapacitor with fossil fuel-based waste activated carbons

Abstract

The invention relates to a method in which dyes, which are harmful to the environment and need to be removed, are incorporated as heteroatoms into activated carbon to be produced from coal and lignite, for use in a supercapacitor.

Description

[0001] DESCRIPTION

[0002] METHOD FOR PREPARING A SUPERCAPACITOR WITH FOSSIL

[0003] FUEL-BASED WASTE ACTIVATED CARBONS

[0004] Technical Field

[0005] The invention relates to a method in which dyes, which are harmful to the environment and need to be removed, are incorporated as heteroatoms into activated carbon to be produced from coal and lignite, for use in a supercapacitor.

[0006] Prior Art

[0007] The supercapacitor, also known as a capacitor battery, is a rechargeable circuit element preferred due to the advantages it provides. It is the general name given to capacitors whose charging capacity is 10 to 100 times higher than ordinary capacitors. They are also known as capacitor batteries or ultracapacitors. Compared to ordinary models, they charge faster and have a higher capacity. In addition, the supercapacitor wears out less compared to ordinary models.

[0008] In energy storage systems, the greatest cost is generally constituted by electrode materials. Among energy storage systems, supercapacitors are systems whose use has been increasing in recent years due to their advantages such as being able to be charged quickly, being easier to produce, being able to store electricity both physically and chemically, having high power densities, being more environmentally friendly in terms of the substances they contain, and having very long shelf lives. However, compared to other energy storage systems, their energy densities are at lower levels. The most commonly used electrode materials for supercapacitors are activated carbon, graphene, carbon nanotube, carbon aerogel, and metals / metal oxides. In commercial supercapacitors, activated carbons are mostly used. Activated carbons, due to their high surface area and porous structures, contain a large number of active sites. Therefore, their adsorption properties are quite good.

[0009] In developed countries, the use of fossil fuels such as coal and lignite for generating heat and electricity by burning has been banned or restricted. These substances are being utilized for the production of high value-added materials. The production of activated carbon is one of these utilizations. Activated carbons produced from coal and lignite are frequently encountered in studies where, in addition to being used in adsorption applications, their evaluation as electrode materials for supercapacitors is investigated. However, how activated carbons produced from coal and lignite can be utilized after adsorption applications has never been addressed. This issue has necessitated studies on preparing supercapacitors with fossil fuel-based waste activated carbons.

[0010] In the document titled “Bazik Boyar Maddelerin Agagh Komurlerinden Eide Edilen Aktif Karbon Uzerinde Adsorpsiyonu” (Mahamanhoglu, M., Kizilgikli, I., & inarh, A. (2006). Selquk Universitesi Miihendislik, Bilim ve Teknoloji Dergisi, 21(3), 21-32.), a solution regarding the adsorption of dyes on activated carbons obtained from coal raw material is explained. The adsorption of Basic Yellow and Basic Blue onto activated carbon was examined as single and binary components, and the adsorption rate constants were calculated.

[0011] In the document titled “Aktif Karbon Adsorpsiyonu lie Boyarmadde Giderimi” (Erkut, E. (2008). Yiiksek lisans tezi, Anadolu Universitesi) the adsorption of Reactive Blue 19 and Reactive Orange 16 dyes with activated carbon is demonstrated, and solutions for the treatment of wastewater are proposed.

[0012] CN105384169A discloses a method for obtaining coal-based activated carbon and for using the obtained activated carbon in a supercapacitor.

[0013] In the prior art, there has been a need to develop a method relating to the incorporation of dyes, which are harmful to the environment and need to be removed, as heteroatoms into activated carbon to be produced from coal and lignite, for use in a supercapacitor.

[0014] Objectives of the Invention

[0015] The object of this invention is to develop a method for incorporating dyes, which are harmful to the environment and need to be removed, as heteroatoms into activated carbon to be produced from coal and lignite, for use in a supercapacitor.

[0016] Another object of the invention is to develop the use of activated carbons, which are in a waste state after adsorption applications, as raw materials for supercapacitors without being disposed of.

[0017] Another object of the invention is to promote environmental benefits by enabling the reuse of waste activated carbons for another application without requiring any additional chemical treatment.

[0018] Detailed Description of the Invention

[0019] The invention relates to a method for incorporating dyes, which are harmful to the environment and need to be removed, as heteroatoms into activated carbon to be produced from coal and lignite, for use in a supercapacitor, and it comprises:

[0020] Producing activated carbon raw material using coal and lignite,

[0021] Applying a purification process to regulate the groups present on the surface of the produced raw material and to increase production yield, Homogenizing the pretreated raw material by mixing it with a sonicator, Carbonizing the raw material in a thermal treatment furnace at different temperatures and durations,

[0022] Mixing the carbonized raw material with activation chemicals such as H3PO4, KOH, K2CO3, NaOH, and Na2COs in specific weight ratios and for specific durations,

[0023] Activating the raw material-activation chemical mixture, Washing and drying the activated carbon obtained after activation, Optionally, performing the purification process at this step as well, Preparing solutions containing the dyes to be added to the activated carbon (Reactive Blue 4, Reactive Blue 19, Reactive Blue 21, Reactive Yellow 5, and Reactive Orange 16),

[0024] Adding activated carbon to the solution,

[0025] Mixing the dye solution with the activated carbon,

[0026] Separating the solid and liquid materials by processing the mixed solution in a centrifuge,

[0027] Washing the separated solid material with distilled water and drying it, Mixing the activated carbons prepared with waste dyes with carbon black and binders such as poly vinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), and polytetrafluoroethylene (PTFE),

[0028] Spraying the mixture onto the current collector using a spray gun, Drying the sprayed current collectors in an oven.

[0029] The invention can be implemented using commercially available carbonized raw materials, as well as carbonized raw materials that can be produced within the scope of the invention for its application. The preliminary processes carried out for the preparation of electrode materials for supercapacitors follow the steps below.

[0030] First, coal or lignite is ground in a mill to produce a powdered form, and the powdered raw material is passed through sieves to carry out the raw material production process. The sieves used in this process have pore sizes of 1-100 pm. Thus, within the scope of the invention, powders with a particle size of 1-100 pm are used.

[0031] In the selected coal and lignite samples, the nitrogen content must be at least 4% and the sulfur content must be at least 5%. The nitrogen and sulfur content of the starting material will affect the amount of nitrogen and sulfur present in the structure of the activated carbon to be produced, thereby influencing the energy storage performance. When coal and lignite with the specified nitrogen and sulfur contents are used, activated carbon samples naturally containing nitrogen and sulfur can be produced. This selection in the starting material eliminates the need for additional surface modification processes on the activated carbons. Furthermore, due to the nature of the dyes to be adsorbed, the additional nitrogen and sulfur content incorporated into the structure will enhance the energy storage performance without requiring a second process.

[0032] A purification process can be applied to the sieved raw material in order to regulate the functional groups on its surface, increase the surface area of the product to be produced, and improve production yield. For this object, the produced raw materials are first mixed with HC1 at a concentration of up to 1 M for 1 hour. The mixture is washed with distilled water until it reaches a pH of 7 and then dried at 105 °C. The dried product is then mixed with HF at a concentration of up to 1 M for 1 hour. The mixture is washed with distilled water until a neutral pH is reached and dried at 105 °C.

[0033] The purification process in the presence of acid can be applied directly to coal or lignite. No pretreatment is required for the waste dye.

[0034] The invention can be implemented using commercially available activated carbon, as well as activated carbon that can be produced within the scope of the invention for its application. The production of activated carbon for supercapacitors follows the steps below.

[0035] The pretreated powdered coal or lignite samples are homogenized by intensive mixing or by using a sonic ator.

[0036] The raw material is placed in a crucible and carbonized in a thermal treatment furnace under a nitrogen (N2) gas atmosphere at temperatures ranging from 200 to 700 °C and for time intervals of 0.5 to 2.5 hours, using different temperature and duration conditions. Mixtures of the carbonized raw material with activation chemicals such as H3PO4, KOH, K2CO3, NaOH, and Na2COs are prepared at weight ratios of 1 :0.5, 1 : 1, 1 : 1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, and 1:5. The prepared mixtures are stirred on a magnetic stirrer for different durations of 1, 2, 4, 8, 12, 16, 24, and 48 hours.

[0037] The carbonized raw material-activation chemical mixture is activated in a thermal treatment furnace under a nitrogen (N2) gas atmosphere (0.05-0.5 L / min) at different temperatures of 450 °C, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C, 800 °C, 850 °C, and 900 °C, and for different durations of 0.5 h, 1 h, 1.5 h, and 2 h.

[0038] The activated carbon samples produced after activation are washed with distilled water until they reach a pH of 7 and then dried at 105 °C.

[0039] If the raw materials have not undergone acid purification during the preliminary preparation stage, the purification process is carried out at this step. The dried samples are first mixed with HC1 at a concentration of up to 1 M for 1 hour and then washed with distilled water until a pH of 7 is reached, followed by drying at 105 °C. The dried samples are then mixed with 1 M HF for 1 hour, subsequently washed with distilled water until a pH of 7 is reached, and dried again at 105 °C.

[0040] The produced activated carbons are stored in a desiccator or in a sealed sample storage container.

[0041] The preparation of electrode active material for supercapacitors follows the steps below.

[0042] Solutions containing dyes (Reactive Blue 4, Reactive Blue 19, Reactive Blue 21, Reactive Yellow 15, Reactive Black 5, and Reactive Orange 16) at concentrations of 10 ppm to 2000 ppm are prepared in volumes ranging from 20 mL to 1 L.

[0043] Activated carbon produced in amounts ranging from 0.01 g to 10 g is added to the solution, and the container holding the solution is sealed. The mixture containing the dye and activated carbon is stirred on an orbital shaker at a temperature range of 5 °C to 50 °C and a stirring speed of 50-500 rpm for 0.5 to 24 hours. At this stage, the dye is adsorbed onto the activated carbon structure.

[0044] After the stirring process, the solution is transferred to Falcon tubes. The Falcon tubes are properly placed in a centrifuge, and centrifugation is carried out at a speed of 5,000-15,000 rpm for 5-30 minutes. As a result of the process, the settled solids at the bottom are separated from the liquid above, and the solids are collected. This process can be repeated as many times as necessary until all solid material is collected.

[0045] The produced solid material, containing waste dye adsorbed onto the activated carbon, is washed with distilled water and dried at 105 °C.

[0046] The dried electrode active material is stored in a sealed container in a desiccator for subsequent use.

[0047] After completing the described steps, the preparation of the supercapacitor cell proceeds as follows:

[0048] The waste activated carbon samples with adsorbed dye are mixed with carbon black and binders such as polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), and polytetrafluoroethylene (PTFE). The mass ratios of activated carbon- binder-carbon black are adjusted to different values, including 80-20-0, 80-15-5, 80-10-10, 80-5-15, 80-0-20, 85-15-0, 85-10-5, 85-5-10, 85-0-15, 90-10-0, 90-5-5, and 90-0-10. PVDF is dissolved in N-methyl-2-pyrrolidone, while CMC and PTFE are dissolved in water.

[0049] The prepared mixture is sprayed onto the current collector using a spray gun. The current collectors coated with the activated carbon-binder-carbon black mixture are dried in a vacuum oven. The dried current collectors can be used in a three- electrode supercapacitor (half-cell) system in the presence of aqueous solutions such as KOH, H2SO4, Na2SO4, or in the presence of various ionic or organic electrolytes, along with a Pt reference electrode and a counter electrode compatible with the electrolyte solution used. Two of the dried current collectors are prepared for use as a full cell by first immersing them for 1 to 6 hours in an aqueous electrolyte such as KOH, H2SO4, H3PO4, Na2SO4, or in various ionic or organic electrolytes such as tetraethylammonium tetrafluoroborate (Et4NBF4), 1 -butyl- 1- methylpyrrolidinium tetrafluoroborate (PYR14 BF4), 1 -butyl- 1- methylpyrrolidinium bis-(trifluoromethylsulfonyl)imide (PYR14 TFSI), 1-propyl- 1-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR13 FSI), to ensure adequate wetting of the current collectors. A separator is positioned between the wetted current collectors, and the collectors are properly packaged to ensure sealing. If a gel or solid electrolyte is to be used for the full cell, the relevant electrolyte can be applied directly between the two current collectors without any wetting process.

[0050] The inventive method can be applied individually for each of the dyes Reactive Blue 4, Reactive Blue 19, Reactive Blue 21, Reactive Yellow 15, Reactive Black

[0051] 5, and Reactive Orange 16, as well as for each of the electrolytes KOH, H2SO4, H3PO4, Na2SO4, Et4NBF4, PYR14 BF4, PYR14 TFSI, and PYR13 FSI.

Claims

CLAIMS1. A method for preparing a supercapacitor in which harmful dyes, which need to be removed from the environment, are added as heteroatoms to the activated carbon formed from coal and lignite, characterized in that it comprises;Producing activated carbon raw material using coal and lignite, Applying purification process to regulate the groups on the surface of the produced raw material for increase the production efficiency, Homogenizing the pre-treated raw material by mixing it with a sonicator, Carbonizing the raw material in a heat treatment furnace,Mixing activation chemicals such as H3PO4, KOH, K2CO3, NaOH and NaiCOs into the carbonized raw material and producing activated carbon, Adding solution containing the dyes to be added to the produced activated carbon and mixing,Applying centrifugation to the stirred solution to separate solid and liquid materials,Washing the separated solid with distilled water and drying,Mixing of dye adsorbed waste activated carbon samples with binders such as polyvinylidene difluoride (PVDF), carboxymethyl cellulose (CMC), polytetrafluoroethylene (PTFE) in the presence of carbon black,Spraying the mixture into the current collector with a spray gun and drying.

2. A method according to claim 1, characterized in that the activated carbon raw material has a nitrogen content of at least 4 % and a sulphur content of at least 5 %.