Synthesis of prussian blue analogues, production of carbon composites and electrochemical and In Silico investigation of their performance in sodium ion batteries

The increasing global demand for energy can be met by renewable energy technologies without causing harm to the environment. In this context, electrochemical energy storage systems play an important role in ensuring uninterrupted energy supply. Among these systems, sodium-ion batteries (SIB) stand out as an economical and sustainable alternative to lithium-ion batteries (LIB). In this thesis, Prussian Blue Analogs (PBA), which can be used as cathodes in SIBs, have been successfully synthesized by a scalable precipitation method suitable for industrial production. By optimizing the production parameters in the synthesis of iron-based PBA, manganese doped iron-based PBA and iron-based PBA containing nitrogen doped graphene (N-GN) were produced under optimum conditions and characterized by various physicochemical and electrochemical analyses. In accordance with the findings obtained during the synthesis and characterization stages, Fe-PBA-23 was found to exhibit high crystallinity and a low crystalline water content, which can be attributed to the optimized synthesis conditions. The electrochemical analysis results indicated that Fe-PBA-23 has the potential to serve as a cathode material for sodium ion batteries. The Fe-PBA-23 sample was demonstrated to exhibit high capacity and a relatively long cycle life through structural (SEM, XRD, XPS, and TGA) and electrochemical characterization. The micro-sized uniform cubic/prismatic structures and XRD results with high crystallinity values indicated that the structure was formed with minimal crystal defects. The TGA results indicated that Fe-PBA-23 has a low amount of crystalline water (10.554%), which suggests that the material has a long cycle life and stability. In terms of electrochemical performance, Fe-PBA-23 has an initial capacity of ~143 mAh.g-1, which decreased to ~139 mAh.g-1 in the following cycles. Furthermore, after high current densities such as 20.0 C, it exhibited a stable and stable structure. The capacity of the material was found to be approximately 131 mAh.g-1 at a current density of 0.2 C. The investigation of MnFe-13-PBA-23 and Fe-PBA-23/N-GN samples revealed the significant effects of doping and carbon composite fabrication on PBA morphology and performance. It was observed that defects in the crystal structure of the MnFe-13-PBA-23 sample were sensitive to changes in synthesis time and conditions, and that the desired specific capacity values were not achieved. In contrast, the Fe-PBA-23/N-GN sample demonstrated controlled crystal formation during synthesis, which was attributed to the conductive graphene doping. This sample exhibited high electrochemical performance and long-term durability. The Fe-PBA-23/N-GN sample exhibited a specific capacity of approximately 112 mAh.g-1 in the initial cycle at a current density of 1.0 C and demonstrated its long-term performance by maintaining a capacity value of approximately 66 mAh.g-1 throughout the 500th cycle. In conclusion, the findings of this study demonstrate that the performance of cathode materials can be enhanced by optimizing additives and synthesis conditions. Furthermore, the combination of graphene and other carbon-based additives allows for further improvement in battery performance and adaptation to a wide range of applications. In this context, the study is regarded as an important step that will contribute to the development of new strategies in energy storage technologies.