PEDOT:PSS-CB based interdigitated supercapacitors

Altun, Enes Can
Süreli Yayın başlığı
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Graduate School
The globe will meet the need for energy in many different ways as global energy consumption keeps rising. In order to enhance dependable and renewable energy and balance supply and demand, energy storage systems are now being expanded. Although significant progress has been achieved in the development of high-performance fuel cells and li-ion batteries, their applicability in many industries has been constrained by their poor power density and high maintenance requirements. Because they have qualities that conventional energy storage devices lack, supercapacitors have recently attracted a lot of attention. A key feature of energy storage devices is that they deliver high power density while also having a low charge-discharge rate. They offer high power density at the same time as a low charge-discharge rate, which is an important characteristic of energy storage devices. In addition to many renewable generation methods for energy production, the importance of storing this energy and using it later is obvious. Today, energy storage devices are used in automobiles, telephones, and all areas where energy is used. Frequently used storage devices can be supplied with Li-ion batteries, supercapacitors, and capacitors. The usage area of traditional capacitors has decreased rapidly from the past to the present. For this reason, studies between batteries and supercapacitors have been increasing rapidly in recent years and countries with high energy needs are investing in these areas. Batteries, especially li-ion batteries, are the most frequently encountered energy storage devices, from phones to automobiles. Although high energy capacity is its most important feature, different energy storage has been sought due to its limited lifetime, inability to withstand high cycles, lack of high power density and not being environmentally friendly after the end of its useful life. In response to this need, research on supercapacitors has brought to mind the idea of whether they can replace batteries. Supercapacitors are preferred due to the high number of cycles, high energy and power density, and flexible working areas. Besides the types of supercapacitors, there are also different configurations. Although sandwich-type supercapacitors are generally used, interdigitated supercapacitors have been used recently with the development of different production methods. Although conventional sandwich-type supercapacitors have relatively high capacitance, they have high ion transport resistance and low active surface area. Therefore, the power density is low. The production of interdigitated supercapacitors can be fast, wearable, flexible, and small in size. In on-chip applications, interdigitated supercapacitors can be applied to any surface in the form of a film. This study, it was tried to give general information about supercapacitors. It is aimed to operate devices that do not require high energy by connecting high-capacity comb supercapacitors in series. PEDOT:PSS polymer material was used as the electrode material due to its semiconductor and excellent electrical performance. PVA gel-based xxii material was preferred as the electrolyte. As a characterization method, supercapacitors were analyzed in detail using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) methods. To obtain interdigitated supercapacitors, patterns were created on the electrode surfaces by laser etching method. For this purpose, a laser with a 15 Watt power and a wavelength of 450 nm was used. To be able to process the patterns precisely, the laser was mounted on a plotter and the patterns were automatically processed by means of software. Since the conductivity of the PEDOT:PSS material used as the electrode material is not at a sufficient level, first of all, some materials were doped in order and the conductivity amount was aimed to reach the desired level. The doped materials are DMSO, ethylene glycol/methanol, and carbon black (CB), respectively. As a result of the added materials, PEDOT:PSS achieved the desired high conductivity. The glass surface with dimensions of 25mmx25mm was thoroughly cleaned with alcohol and water, and then the PEDOT:PSS-CB material, which was prepared beforehand, was applied to the surface by the drop-casting. Then, it was dried at 65 ⁰C for 2 hours and a thin film was obtained on the glass surface, and the coating process was completed. Then, a comb structure was formed on this surface by the laser etching method and the electrode was made ready for use. A copper current collector is affixed to the prepared electrode. Then, these current collectors are covered with insulating tape so that they do not come into contact with the electrolyte. Then, the prepared PVA-based gel electrolyte containing 6M KOH was poured onto the comb structures with the help of a syringe. The prepared energy cell is placed in a closed container so that the electrolyte does not dry out. In this way, both single and eight different samples were prepared. It is aimed to reach high voltage values by connecting the eight samples prepared in series. The operating range of the single cell is -1 V +1V and the operating range of the octa-series cell is determined as -6V +6V. As a result of the study, eight cells connected in series and a red LED bulb worked for 1 minute.
Thesis (M.Sc.) -- İstanbul Technical University, Graduate School, 2023
Anahtar kelimeler
capasitors, capacitors, nanotechnology, nanoteknoloji