Preparation of new generation poly(N-isopropylacrylamide) and poly(acrylicacid) based composite electrodes and supercapacitor applications

Supercapacitors have gained notable attention as a crucial solution to the energy storage challenge because of their impressive power density, rapid charge-discharge rate, eco-friendliness, and long cycle life. The efficiency of supercapacitors is largely determined by the characteristics of their electrode materials. Poly(N-isopropylacrylamide) (PNIPAM) and poly(acrylic acid) (PAAc) polymers were synthesized by radical polymerization method. The polymers were obtained after sequential mixing using polymers monomer, crosslinker (MBA), accelerator (TEMED) and radical initiator (APS). Afterward, polymers were synthesized as composite (M/CNT-g-PAAc) with Carbon nanotube (CNT) and mono-metal M(Pd, Pt, Ru, Co, Mo, Fe, Ga, Bi, Ni)/CNT catalysts. Polymers and metal-doped polymers were analyzed by Fourier Transform Infrared Spectroscopy (FT-IR), Micro Raman Spectrometer (RAMAN) and Scanning electron microscopes and elemental mapping (SEM-EDX), X-ray diffraction (XRD) methods. In this thesis, new generation electrodes with high capacitance were developed by coating carbon felt-based electrode material with high ionic conductivity polymers and M(Pd, Pt, Ru, Co, Mo, Fe, Ga, Bi, Ni)/CNT composites. The capacitive performances of the electrodes were examined by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques in 1.0 M H2SO4 aqueous electrolyte. The resulting PAAc-g-(Ru/CNT) and PAAc-g-(Ni/CNT), which function as supercapacitor electrodes, exhibit a high specific capacitances of 1294.5 F g-1 at 5.0 mV s-1 and 680.0 F g-1 at 2.0 mA cm-2, respectively. Additionally, these electrodes demonstrate a high capacitance retention of up to 97.7% and 94.1% after 1000 cycles, respectively, showcasing their extended cycle life and strong electrochemical stability. These results contribute to the advancement of the field of energy storage and provide practical solutions for developing energy storage devices with higher efficiency and sustainability. This thesis provided new approaches for metal/carbon composites suitable to energy storage and suitable to energy storage and energy conversion devices with ionic conducting polymers as an electrode material, as well as insights into the creation of new composites for high-performance supercapacitors.