Production of carbon-based materials from pomegranate and black carrot wastes and investigation of supercapacitor device performances

In this thesis study, pomegranate peel, pomegranate seed and black carrot pulp were investigated for use as anode materials in supercapacitors and sodium ion batteries, which are one of the energy storage systems. For all wastes, initial raw samples were carbonized in a cylindrical oven at 400-800 oC at a heating rate of 10 oC/min in a 100 ml/min N2 inert environment and then impregnated with 1/3 and 1/4 KOH. Afterward, activated carbons were obtained by activation at 800 C in a 100 ml/min N2 inert environment. On the other hand, the initial raw samples for all wastes were carbonized in a home-type modified microwave oven at 600 and 700 W power in a 100 ml/min N2 inert environment for 10 minutes and then treated with 1/4 KOH. Finally, activated carbons were obtained by activation at 700 W for 15 minutes in an inert environment of 100 ml/min N2. The obtained activated carbon (AC) samples were characterized by BET, XRD, FTIR, Raman spectroscopy, SEM, and elemental analysis, and supercapacitor measurements were then made. According to the BET analysis results, it was determined that the sample with the highest surface area, 1195 m2/g, belonged to the pomegranate seed obtained in the cylindrical oven. According to the results of elemental analysis, it was determined that the highest carbon content, 71.34%, was obtained in the microwave oven with a power of 700 W. It was determined that XRD, FTIR and Raman analysis results supported the structural nature of the activated carbons obtained, and according to SEM images, porous structures were obtained in all activated samples compared to the initial raw samples. After the characterization process, electrochemical tests (CV, EIS, GCD) were carried out on the produced activated carbons for use in super capacitors. Accordingly, the highest capacitance value at 4 000 cycles was obtained in the black carrot pulp (AKH64) sample with 177 F/g at 0.1 A/g. In addition, hydrochars were obtained by hydrothermal carbonization of raw samples at 200 and 250 oC for 2, 3 and 4 hours. The obtained hydrochars were subjected to thermal treatment at 1200 oC for 1 hour at a heating rate of 3 oC/min to obtain hard carbons. The hard carbon samples were characterized by BET, XRD, FTIR, Raman spectroscopy, SEM and elemental analyses. According to the results of elemental analysis, it was determined that the highest carbon content was obtained in pomegranate peel, 75.83%. The usability of hard carbon (HC) materials as anode materials in sodium-ion batteries were investigated through characterization processes.