Supercapacitor comprising radioactive component and the preparation method thereof

Abstract

The invention relates to a supercapacitor comprising a carbon nanotube (CNT) electrode containing a radioactive component or a graphene oxide (GO) electrode containing a radioactive component and the method of preparing this supercapacitor. The supercapacitor of the invention has a high energy density, a long-lasting charge-discharge cycle and a high Coulombic efficiency. The radioactive component used in the supercapacitor of the invention is uranium (U).

Description

[0001] SUPERCAPACITOR COMPRISING RADIOACTIVE COMPONENT AND THE PREPARATION METHOD THEREOF

[0002] Technical Field of the Invention

[0003] The invention relates to a supercapacitor comprising a carbon nanotube (CNT) electrode containing a radioactive component or a graphene oxide (GO) electrode containing a radioactive component and the method of preparing this supercapacitor. The supercapacitor of the invention has a high energy density, a long-lasting chargedischarge cycle and a high Coulombic efficiency.

[0004] State of the Art

[0005] The world's increasing energy needs have made it necessary to develop new energy sources and to store energy in order to use existing energy resources more efficiently. This necessity has pushed the scientific community and world powers to focus on energy storage devices. Stored energy is used to meet energy needs when the main energy source is not available or insufficient. Therefore, R&D studies have focused on energy storage devices that can operate more efficiently [1 , 2],

[0006] In the state of the art, one of the energy storage devices on which R&D studies in the field of energy are concentrated is supercapacitors. Supercapacitors are promising energy storage systems due to their low cost and high energy density. Supercapacitors are energy storage devices that have higher charge-discharge speed, power density and longer cycle life than batteries. A supercapacitor is a type of capacitor that can store 10 to 100 times more energy per unit mass or volume than other capacitors. It can be charged faster and simpler than normal ones. The reason why supercapacitors have a very long life is that they wear very little despite high-intensity use. Due to the ever-increasing energy need in the world, the importance of energy storage devices has increased, and research has focused on supercapacitors, anticipating that the potential of supercapacitors can be increased. Supercapacitors are sometimes used in electronic circuits instead of batteries. In addition, other areas of use of the supercapacitor are known as wireless charging technology, wearable technological devices, cars, mobile phones, televisions, computers and air conditioning devices, etc. In addition, due to their high energy and power density, supercapacitors are used in electronics, military fields, and hybrid electric vehicles. In summary, considering the developing technology, the reasons why supercapacitors are preferred in the energy field are their high storage capacity, environmental friendliness, long cycle life, high power density / energy density and fast charge-discharge capabilities. Considering all these advantages, supercapacitors are at the top of the preference list, and it is predicted that supercapacitors will be used in all areas of the electronics industry in the future.

[0007] Some of the mostly common active materials used in the fabrication of supercapacitors are metal oxides, conductive polymers and their composites with other materials such as carbon nanotubes (CNT). In supercapacitors, charge storage occurs in the electrodes. The driving force behind the utilization of carbon nanotubes as supercapacitor electrodes is their high conductivity close to metal nanoparticles, large specific surface area and controllable surface morpholohy. Another material employed as electrode material in supercapacitors is carbon-based materials (graphene, graphene oxide, etc.) with a porous structure. The reasons why carbon-based materials are preferred as electrode materials in supercapacitors are that these materials have a high specific surface area, good electrical conductivity, and excellent cyclic stability in harsh environments.

[0008] Although state-of-the-art supercapacitors can store high amounts of energy, the charge-discharge cycles of these supercapacitors are quite short. In the literature, it is generally possible to come across supercapacitors with 5,000 cycles charge-discharge cycles. On the other hand, a supercapacitor with 10,000 cycles exhibits a high level of performance.

[0009] For reasons such as the facts that the charge-discharge cycles of supercapacitors in the state of the art are quite short, that the efficiency of capacitors in the state of the art with 10,000 charge-discharge cycles can reach up to a maximum of 92%, in other words, a supercapacitor with both high charge-discharge cycle life, high energy density and high Coulombic efficiency is not available in the state of the art, it has become necessary to develop a supercapacitor that can store high amounts of energy, has a long-lasting charge-discharge cycle and has high Coulombic efficiency. Brief Description and Aims of the Invention

[0010] In the invention, a supercapacitor comprising a carbon nanotube (CNT) electrode containing a radioactive component or a graphene oxide (GO) electrode containing a radioactive component and the method of preparing this supercapacitor are described. The supercapacitor of the invention has a high energy density, a long-lasting chargedischarge cycle, and a high Coulombic efficiency. The radioactive component used in the supercapacitor of the invention is uranium (U).

[0011] The most important aim of the invention is to provide a supercapacitor with high energy density, a long-lasting charge-discharge cycle and high Coulombic efficiency. In the invention, the provision of a supercapacitor with high energy density, superior chargedischarge cycle performance and high Coulombic efficiency is achieved by incorporating uranium into graphene oxide (GO) or carbon nanotube (CNT) structures. As a result of doping even small amounts of uranium atoms into graphene oxide (GO) or carbon nanotube (CNT) structures, the specific capacitance and energy density values of supercapacitors are increased approximately 1 .5 times. Supercapacitor cells in which uranium-doped GO and CNT structures are used as electrodes exhibit higher capacitive behaviour compared to supercapacitor cells in which only GO and CNT structures are used as electrodes. When the specific capacitance values of uranium- doped graphene oxide samples were examined, it was observed that as the amount of uranium atoms in the structure increased, the specific capacitance values of the supercapacitor increased with the presence of the pseudo-capacitative effect.

[0012] An aim of the invention is to provide a supercapacitor having a long-lasting chargedischarge cycle. In the invention, providing a supercapacitor with a long-lasting chargedischarge cycle is achieved by incorporating uranium into graphene oxide (GO) or carbon nanotube (CNT) structures. As a result of doping even small amounts of uranium atoms into graphene oxide (GO) or carbon nanotube (CNT) structures, the specific capacitance and energy density values of supercapacitors are increased approximately 1 .5 times. Another aim of the invention is to provide a supercapacitor with high Coulombic efficiency. In the invention, a high Coulombic efficiency supercapacitor is provided by incorporating uranium into GO or CNT structures. As a result of doping even small amounts of uranium atoms into graphene oxide (GO) or carbon nanotube (CNT) structures, the specific capacitance and energy density values of supercapacitors are increased approximately 1.5 times. In addition, cycle stabilities (cycle performances) have been determined to be over 95% even at high current density.

[0013] An aim of the invention is to provide a supercapacitor with a high specific capacitance value. In the invention, a supercapacitor with a high specific capacitance value is provided by doping uranium to the GO or CNT structures in the structure of the supercapacitor. When the specific capacitance values of uranium-doped graphene oxide samples were examined, it was observed that as the amount of uranium atoms in the structure increased, the specific capacitance values increased with the presence of the pseudo-capacitive effect.

[0014] Description of Drawings

[0015] Figure 1. Cyclic voltammetry (CV) voltammograms of graphene oxide (GO) based supercapacitor cells obtained at different potential scan rates in 6.0 M potassium hydroxide (KOH) electrolyte

[0016] Figure 2. CV voltammograms of carbon nanotube (CNT) based supercapacitor cells obtained at different potential scan rates in 6.0 M KOH electrolyte

[0017] Figure 3. Comparison of CV voltammograms of (A) GO-based, (B) CNT-based supercapacitor cells obtained at 20 mV.s-1potential scan rate in 6.0 M KOH electrolyte

[0018] Figure 4. Galvanostatic charge-discharge (GCD) curves of GO-based supercapacitor cells obtained at different current densities in 6.0 M KOH electrolyte

[0019] Figure 5. GCD curves of CNT-based supercapacitor cells obtained at different current densities in 6.0 M KOH electrolyte

[0020] Detailed Description of the Invention The invention relates to a supercapacitor comprising a carbon nanotube (CNT) electrode containing a radioactive component or a graphene oxide (GO) electrode containing a radioactive component and the method of preparing this supercapacitor. The supercapacitor of the invention has a high energy density, a long-lasting chargedischarge cycle and a high Coulombic efficiency. The radioactive component used in the supercapacitor of the invention is uranium (U).

[0021] As a result of doping 0.02% - 0.60% by mass of uranium atoms in graphene oxide (GO) or carbon nanotube (CNT) structures relative to the total masses of GO or CNT, the specific capacitance and energy density values of the supercapacitor are increased approximately 1.5 times. Supercapacitor cells in which uranium-doped GO or CNT structures are used as electrodes exhibit higher capacitive behaviour compared to supercapacitor cells in which bare GO or CNT structures are used as electrodes. When the specific capacitance values of uranium-doped graphene oxide samples were examined, it was observed that as the amount of uranium atoms in the structure increased, the specific capacitance values in supercapacitors increased with the presence of pseudo capacitative effect. The carbon nanotube (CNT) electrode, which is an electrode in the supercapacitor that is the subject of the invention, contains 0.02- 0.6% uranium by mass relative to the total mass of the electrode or the graphene oxide (GO) electrode, which is another electrode to be used as an alternative instead of CNT in the supercapacitor, contains 0.02-0.6% uranium by mass compared to the total mass of the electrode.

[0022] Preparation method of the supercapacitor that is the subject of the invention comprises the process steps of: i. boiling carbon nanotubes (CNTs) in a 3:1 ratio of nitric acid:sulfuric acid (HNO3:H2SO4) solution under the reflux and obtaining carbon nanotubes (CNTs) with functional groups, or mixing graphite with sulfuric acid (H2SO4) and controlling it by lowering the solution temperature, slowly adding potassium permanganate (KMnO4) to the resulting mixture and continuing the mixing process, slowly adding pure water to the mixture and mixing, cooling the mixture after mixing, and then adding hydrogen peroxide (H2O2) to the solution in a controlled and dropwise manner, mixing the solution and filtering the resulting solution, reducing with hydrozinium sulfate and distilled wate after filtering, then allowing the solution to filter and obtaining graphene oxide (GO) solid, ii. adding uranium acetate to the resulting carbon nanotube (CNT) or graphene oxide (GO) solid powder and sonication of CNT or GO solutions obtained by doping uranium acetate in an ultrasonic bath to bind uranium to carbon nanotubes or graphene oxide and obtaining uranium-carbon nanotube (U- CNT) or uranium-graphene oxide (U-GO), iii. fabricating of U-CNT or U-GO based supercapacitor electrodes by casting electrode slurry containing electrode active material, carbon black and polyvinylidene fluoride dispersed in solution containing N-methyl-2- pyrrolidone, deionized water and isopropyl alcohol, iv. subjecting the electrode slurry to ultrasound to obtain uniform distribution before coating it on a nickel foam as a current collector, v. separating two identical U-CNT or two identical U-GO based electrodes with a glass fibre separator immersed in the electrolyte and placing the Swagelok type cell in the two-electrode system, vi. Using 3.0 M H2SO4 as the electrolyte solution and adjusting the total mass loading on each electrode to be 2.5-5 mg. cm2and obtaining the supercapacitor.

[0023] In one embodiment of the invention, the preparation method of the supercapacitor that is the subject of the invention comprises the process steps of: i. boiling 1.0-5.0 grams of carbon nanotubes (CNTs) in a 3:1 ratio nitric acid:sulfuric acid (HNO3:H2SO4) solution under the reflux for 4-6 hours and obtaining carbon nanotubes (CNTs) with functional groups or mixing 0.5-10 grams of graphite with 30-60 mL sulfuric acid (H2SO4) and controlling the solution temperature by lowering it, slowly adding 1.5-3.0 grams of potassium permanganate (KMnO4) to the resulting mixture and continuing the mixing process for 30-60 minutes, slowly adding 25-50 mL of pure water to the mixture and mixing for 1 -2 hours, cooling the mixture after 1 -2 hours of mixing and then adding 30-60 ml of hydrogen peroxide (H2O2) to the solution in a controlled and dropwise manner and mixing the solution and filtering the resulting solution, reducing it with hydrozinium sulfate and distilled water after the filtration process, then allowing the solution to filter for 24-48 hours and obtaining graphene oxide (GO) solid, ii. adding 1 -10% uranium acetate by mass to the obtained carbon nanotube (CNT) or graphene oxide (GO) solid powder and sonication of uranium acetate added-CNT or -GO solutions in an ultrasonic bath at 40°C for 1 -2 hours in order to bind uranium to carbon nanotubes or graphene oxide and obtaining uranium-carbon nanotube (U-CNT) or uranium-graphene oxide (U-GO), iii. fabricating of U-CNT or U-GO based supercapacitor electrodes by casting electrode slurry containing 80-90% electrode active material, 1 -5% carbon black and 1 -5% polyvinylidene fluoride by mass dispersed in a solution containing 8 pl volume of N-methyl-2-pyrrolidone, 400-800 pl deionized water and 600-1200 pl isopropyl alcohol, iv. subjecting the electrode slurry to ultrasound for one hour to obtain uniform distribution before coating it on a nickel foam as a current collector, v. separating two identical U-CNT or two identical U-GO based electrodes with a glass fibre separator immersed in the electrolyte and placing the Swagelok type cell in the two-electrode system, vi. using 3.0 M H2SO4 as the electrolyte solution and adjusting the total mass loading on each electrode to be 2.5-5 mg. cm2and obtaining the supercapacitor.

[0024] In one embodiment of the invention, the preparation method of the supercapacitor that is the subject of the invention comprises the process steps of: i. boiling 1 -5.0 grams of carbon nanotubes (CNTs) in a 3:1 ratio nitric acid:sulfuric acid (HNO3:H2SO4) solution under the reflux for 4 hours and obtaining carbon nanotubes (CNTs) with functional groups or mixing 0.5 grams of graphite with 30 mL sulfuric acid (H2SO4) and controlling the solution temperature by lowering it, slowly adding 1 .5 grams of potassium permanganate (KMnO4) to the resulting mixture and continuing the mixing process for 30 minutes, slowly adding 25 mL of pure water to the mixture and mixing for 1 hour, cooling the mixture after 1 hour of mixing and then adding 30 ml of hydrogen peroxide (H2O2) to the solution in a controlled and dropwise manner and mixing the solution and filtering the resulting solution, reducing it with hydrozinium sulfate and distilled water after the filtration process, then allowing the solution to filter for 24 hours and obtaining graphene oxide (GO) solid, ii. adding uranium acetate to the obtained carbon nanotube (CNT) or graphene oxide (GO) solid powder at the rate of 10% by mass if carbon nanotube (CNT) is used, and 5% by mass if graphene oxide (GO) is used and sonicating uranium acetate added-CNT or -GO solutions in an ultrasonic bath at 40°C for 1 -2 hours in order to bind uranium to carbon nanotubes or graphene oxide and obtaining uranium-carbon nanotube (U-CNT) or uranium-graphene oxide (U-GO), iii. fabricating of U-CNT or U-GO based supercapacitor electrodes by casting electrode slurry containing 90% electrode active material, 1 % carbon black and 5% polyvinylidene fluoride by mass dispersed in a solution containing 8 pl volume of N-methyl-2-pyrrolidone, 400 pl deionized water and 600 pl isopropyl alcohol, iv. subjecting the electrode slurry to ultrasound for one hour to obtain uniform distribution before casting it on a nickel foam as a current collector, v. separating two identical U-CNT or two identical U-GO based electrodes with a glass fibre separator immersed in the electrolyte and placing the Swagelok type cell in the two-electrode system, vi. using 3.0 M H2SO4 as the electrolyte solution and adjusting the total mass loading on each electrode to be 2.5 mg. cm2and obtaining the supercapacitor.

[0025] The supercapacitor obtained by the method of the invention can store high amounts of energy for a long time and its specific capacitance value is 308 F / g. The chargedischarge cycle of the supercapacitor that is the subject of the invention is 15,000. In addition, the Coulombic efficiency of the supercapacitor is 95%.

[0026] The electrochemical performance of the supercapacitor prepared with the fabrication method that is the subject of the invention was evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques on a Gamry Reference 600+ workstation (Gamry, USA). CV measurements were performed at different potential scan rates ranging from 5 mV.s-1to 100 mV.s-1in the 0-1 .0 V voltage range. GCD tests were examined at different constant current densities in the range of 0.5 A.g-1- 10.0 A.g-1. The cycling stability of supercapacitor cells was examined by the GCD technique over 15,000 consecutive cycles at a current density of 0.1 A.g’1. With the help of the obtained GCD data, specific capacitance (Cs; F.g’1), energy density (E; W.h.kg’1), power density (P; W.kg’1) and cycle stability (%) values were calculated.

[0027] CV voltammograms obtained by cyclic voltammetry technique at different potential scanning rates in the range of 5-100 mV.s-1in a 6.0 M KOH electrolyte for U-GO and U-CNT structures are shown in Figure 1 and Figure 2, respectively. An increase in the electrochemical performance of the structures was observed by doping uranium atoms into the produced GO or CNT-based structures. Attaining a specific capacity of at least 200 F.g-1at a current density of 1.0 A.g-1, Coulombic efficiency being over 90%, energy density being over 20 W.h.kg1, power density being over 5 kW kg-1, and cycle stability being over 90% after 5,000 cycles are indicators of the high performance of the supercapacitor that is the subject of the invention. As can be seen from the CV voltammograms, uranium-doped structures exhibit higher capacitive behaviour compared to supercapacitor cells where only GO or CNT structures are used as electrodes. In the obtained voltammograms, a hump was observed resulting from the pseudo-capacitive contribution of the uranium atoms included in the structure. The l / V curve flattened into a loop after a certain current, it means that the charge is stored with the pseudo-capacitative effect. While Figure 1 shows the CV voltammograms of GO-based supercapacitor cells obtained at different potential scanning rates in a 6.0 M potassium hydroxide (KOH) electrolyte, Figure 2 shows the CV voltammograms of CNT-based supercapacitor cells obtained at different potential scanning rates in a 6.0 M KOH electrolyte. Comparison of the electrochemical properties of supercapacitor cells using GO-based and CNT-based electrodes is shown in Figure 3, and the comparison was carried out at a potential scanning rate of 20 mV.s’1. When the bare GO and CNT samples produced as control samples are compared with uranium-doped GO or CNT-based samples, it is seen that there is an approximately 3-fold increase in the current density values in the CV voltammogram with uranium doping. The main reason for this is that the uranium atom takes part in the redox reaction. If uranium did not undergo redox reactions, it would not be possible to achieve this increase in current density.

[0028] An approximately 3-fold increase in the current density values in the CV voltammogram shows that the supercapacitor of the invention can store more charge than non- uranium-doped GO or CNT. The significant hump at approximately 0.5-0.6 V seen in the CV curves was observed as a result of the redox reaction of the uranium atom and the surface functional groups in the structure. Table 1 and Table 2 show the specific capacitance (Cs; Fg1) values of the GO or CNT-based supercapacitors of the invention, calculated based on the electrode active material mass in 6.0 M sodium hydroxide (KOH) electrolyte, respectively. The highest specific capacitance value was reached as 303.8 F.g’1for the U-CNTU-CNT 10 based supercapacitor cell at a potential scanning rate of 5 mV.s-1. While this value was 195.8 F.g’1for the plain CNT-based supercapacitor cell, it was found to be 220.7 F.g’1and 255.5 F.g’1for U-CNTU-CNT1 and U-CNTU-CNT5 electrodes, respectively. As can be clearly understood from the calculated specific capacitance values, an increase in electrochemical performance was observed with the pseudocapacitative effect as a result of the increase in the doping rates of uranium atoms in the structure. Similarly, when the specific capacitance values of U-GO samples were examined, it was observed that as the amount of uranium atoms in the structure increased, the specific capacitance values increased with the presence of pseudo capacitative effect. While the highest specific capacitance value of the plain GO sample was determined as 182.4 F.g’1at a potential scanning rate of 5 mV.s-1, as a result of SEM EDX analysis, this value was calculated as 279.7 F.g-1for the supercapacitor cell of the U-GO5 sample, which contains the most uranium atoms in its structure (0.13%). For the U-GO10 sample, which contains 0.10% uranium in its structure, this value was determined as 272.3 F.g’1. All obtained results show that specific capacitance and energy density values can be increased approximately 1 .5 times by doping 0.02% - 0.60% uranium atoms into GO or CNT structures. Table 1. Performance parameters of GO-based supercapacitor cells obtained in 6.0 M KOH electrolyte Table 2. Performance parameters of CNT-based supercapacitor cells obtained in 6.0 M KOH electrolyte

[0029] Galvonastatic charge-discharge tests (GCD) of supercapacitors obtained by the preparation method of the invention were carried out at a constant current density of 0.5-10.0 A.g-1and specific capacitance, energy and power density, cycle life and Coulomb efficiency values of the supercapacitor cells were calculated. GCD curves obtained at different current densities of GO-based and CNT-based supercapacitor cells are shown in Figure 4 and Figure 5, respectively. REFERENCES

[0030] [1] Halper, M. S. ve Ellenbogen, J. C. (2006). Supercapacitors: A brief overview, MITRE Nanosystems Group, Virginia, USA.

[0031] [2] Feng, L., Zhu, Y. ve Ding, H. (2014). Recent progress in nickel based materials for high performance pseudocapacitor electrodes, Journal of Power Sources, 267, 430- 444.

[0032] [3] Jyothibasu, J. P. A., Chen, M.-Z., & Lee, R.-H. (n.d.). Polypyrrole / Carbon Nanotube Freestanding Electrode with Excellent Electrochemical Properties for High- Performance All-Solid- State Supercapacitors.

[0033] [4] SH;, B. M. K. (n.d.). High-performance freestanding supercapacitor electrode based on polypyrrole coated nickel cobalt sulfide nanostructures. Scientific reports. Retrieved October 13, 2022, from https: / / pubmed.ncbi.nlm.nih.gov / 35301384 /

Claims

CLAIMS1. A supercapacitor, comprising carbon nanotube (CNT) or graphene oxide (GO) electrode, and comprising 0.02-0.6% uranium by mass relative to the total mass of said carbon nanotube (CNT) or graphene oxide (GO) electrodes.

2. A supercapacitor according to Claim 1 , wherein its capacitance value is 308 F / g.

3. A supercapacitor according to Claim 1 , wherein its charge-discharge cycle is 15.000.

4. A supercapacitor according to Claim 1 , wherein its efficiency is 95%.

5. A method for the preparation of a supercapacitor, comprising the process steps of: i. boiling carbon nanotubes (CNTs) in a 3:1 ratio of nitric acid:sulfuric acid (HNO3:H2SO4) solution in a reflux and obtaining carbon nanotubes (CNTs) with functional groups, or mixing graphite with sulfuric acid (H2SO4) and controlling it by lowering the solution temperature, slowly adding potassium permanganate (KMnO4) to the resulting mixture and continuing the mixing process, slowly adding pure water to the mixture and mixing, cooling the mixture after mixing, and then adding hydrogen peroxide (H2O2) to the solution in a controlled and dropwise manner, mixing the solution and filtering the resulting solution, reducing with hydrozinium sulfate and distilled wate after filtering, then allowing the solution to filter and obtaining graphene oxide (GO) solid, ii. adding uranium acetate to the resulting carbon nanotube (CNT) or graphene oxide (GO) solid powder and sonication of CNT or GO solutions obtained by doping uranium acetate in an ultrasonic bath to bind uranium to carbon nanotubes or graphene oxide and obtaining uranium-carbon nanotube (U-CNT) or uranium-graphene oxide (U-GO), iii. fabricating of U-CNT or U-GO based supercapacitor electrodes by casting electrode slurry containing electrode active material, carbon black and polyvinylidene fluoride dispersed in solution containing N- methyl-2-pyrrolidone, deionized water and isopropyl alcohol, iv. subjecting the electrode slurry to ultrasound to obtain uniform distribution before coating it on a nickel foam as a current collector,v. separating two identical U-CNT or two identical U-GO based electrodes with a glass fibre separator immersed in the electrolyte and placing the Swagelok type cell in the two-electrode system, vi. using 3.0 M H2SO4 as the electrolyte solution and adjusting the total mass loading on each electrode to be 2.5-5 mg. cm2and obtaining the supercapacitor. method according to claim 5, comprising the process steps of: i. boiling 1.0-5.0 grams of carbon nanotubes (CNTs) in a 3:1 ratio nitric acid:sulfuric acid (HNC^FkSC ) solution in a reflux for 4-6 hours and obtaining carbon nanotubes (CNTs) with functional groups or mixing 0.5- 10 grams of graphite with 30-60 mL sulfuric acid (H2SO4) and controlling the solution temperature by lowering it, slowly adding 1.5-3.0 grams of potassium permanganate (KMnC ) to the resulting mixture and continuing the mixing process for 30-60 minutes, slowly adding 25-50 mL of pure water to the mixture and mixing for 1 -2 hours, cooling the mixture after 1 -2 hours of mixing and then adding 30-60 ml of hydrogen peroxide (H2O2) to the solution in a controlled and dropwise manner and mixing the solution and filtering the resulting solution, reducing it with hydrozinium sulfate and distilled water after the filtration process, then allowing the solution to filter for 24-48 hours and obtaining graphene oxide (GO) solid, ii. adding 1 -10% uranium acetate by mass to the obtained carbon nanotube (CNT) or graphene oxide (GO) solid powder and sonication of CNT or GO solutions obtained by doping uranium acetate in an ultrasonic bath at 40°C for 1 -2 hours in order to bind uranium to carbon nanotubes or graphene oxide and obtaining uranium-carbon nanotube (U-CNT) or uranium-graphene oxide (U-GO), iii. fabricating of U-CNT or U-GO based supercapacitor electrodes by casting electrode slurry containing 80-90% electrode active material, 1 - 5% carbon black and 1 -5% polyvinylidene fluoride by mass dispersed in a solution containing 8 pl volume of N-methyl-2-pyrrolidone, 400-800 pl deionized water and 600-1200 pl isopropyl alcohol,iv. subjecting the electrode slurry to ultrasound for one hour to obtain uniform distribution before coating it on a nickel foam as a current collector, v. separating two identical U-CNT or two identical U-GO based electrodes with a glass fibre separator immersed in the electrolyte and placing the Swagelok type cell in the two-electrode system, vi. using 3.0 M H2SO4 as the electrolyte solution and adjusting the total mass loading on each electrode to be 2.5-5 mg. cm2and obtaining the supercapacitor.

7. A method according to Claims 5 or 6, comprising the process steps of: i. boiling 1 -5.0 grams of carbon nanotubes (CNTs) in a 3:1 ratio nitric acid:sulfuric acid (HNC^FkSC ) solution in a reflux for 4 hours and obtaining carbon nanotubes (CNTs) with functional groups or mixing 0.5 grams of graphite with 30 mL sulfuric acid (H2SO4) and controlling the solution temperature by lowering it, slowly adding 1.5 grams of potassium permanganate (KMnC ) to the resulting mixture and continuing the mixing process for 30 minutes, slowly adding 25 mL of pure water to the mixture and mixing for 1 hour, cooling the mixture after 1 hour of mixing and then adding 30 ml of hydrogen peroxide (H2O2) to the solution in a controlled and dropwise manner and mixing the solution and filtering the resulting solution, reducing it with hydrozinium sulfate and distilled water after the filtration process, then allowing the solution to filter for 24 hours and obtaining graphene oxide (GO) solid, ii. adding uranium acetate to the obtained carbon nanotube (CNT) or graphene oxide (GO) solid powder at the rate of 10% by mass if carbon nanotube (CNT) is used, and 5% by mass if graphene oxide (GO) is used and sonicating CNT or GO solutions obtained by doping uranium acetate in an ultrasonic bath at 40°C for 1 -2 hours in order to bind uranium to carbon nanotubes or graphene oxide and obtaining uraniumcarbon nanotube (U-CNT) or uranium-graphene oxide (U-GO), iii. fabricating of U-CNT or U-GO based supercapacitor electrodes by casting electrode slurry containing 90% electrode active material, 1 % carbon black and 5% polyvinylidene fluoride by mass dispersed in asolution containing 8 pl volume of N-methyl-2-pyrrolidone, 400 pl deionized water and 600 pl isopropyl alcohol, iv. subjecting the electrode slurry to ultrasound for one hour to obtain uniform distribution before casting it on a nickel foam as a current collector, v. separating two identical U-CNT or two identical U-GO based electrodes with a glass fibre separator immersed in the electrolyte and placing the Swagelok type cell in the two-electrode system, vi. using 3.0 M H2SO4 as the electrolyte solution and adjusting the total mass loading on each electrode to be 2.5 mg. cm2and obtaining the supercapacitor.

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