Applicability of energy storage by obtaining hard carbon from different biomass precursors

Within the scope of this thesis study, use of two different categories of related biomass resources in energy storage applications was studied based on pomegranate peel and pomegranate seed as biomass sources readily available in nature, and waste firefighting clothing as synthetic biomass source not readily available in nature. In this context, hard carbon, which has been a current issue in recent years and has attracted great interest from researchers, was synthesized and characterized from pomegranate peel, pomegranate seed and waste firefighter suit using direct carbonization, double-stage carbonization and hydrothermal carbonization methods. Subsequently, hard carbons produced from pomegranate seed and pomegranate peel were applied in supercapacitors, while hard carbons produced from waste firefighter suit were used as electrode materials in Na-ion batteries and their electrochemical performances were investigated. As a result of the applied fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), raman spectroscopy, scanning electron microscope (SEM), energy dispersive x-ray analysis (EDX) and brunauer-emmett-teller (BET) characterization processes of the produced hard carbons, it was observed that the synthesized products had a carbon-based, irregular structure, and it was confirmed that the synthesized products were hard carbons. In the supercapacitor application of the hard carbons produced from pomegranate peel and pomegranate seed, CV results showed that the produced electrodes had charge and discharge capacity, and the highest specific capacity was obtained as 5.8 F/g from pomegranate seed at a scan rate of 5 mV/s and 11.4 F/g from pomegranate peel at a scan rate of 5 mV/s. In the Na-ion battery application, initially, a half-cell battery was formed in which the produced hard carbons were used as anodes. In this application, the highest capacities were obtained in the first and second cycles as 410 and 233 mAh g-1, respectively. Galvanostatic cycle tests performed at different temperatures showed that the temperature directly affects the half-cell battery capacity. In addition, it was observed that a large amount of sodium ions were consumed during the formation of the solid electrolyte interface (SEI) in the half-cell battery process. In order to compensate for this sodium ion loss, the two hard carbon samples with the best performance from the half-cell results were selected and after applying the pre-sodiumification technique with electrochemical process, full cells were produced by combining the pre-sodiumified hard carbon samples with Na0.67Mn0.5Fe0.45Ti0.07O2 as the cathode. As a result of the full-cell tests, the highest capacity was obtained as 114,9 mAh g-1 under 2–4 V voltage range and C/10 conditions