Πλοήγηση ανά Συγγραφέας "Daskalakis, Stylianos"

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  • Μικρογραφία εικόνας
    Τεκμήριο
    Electrochemical characterization and understanding of the basic Intercalation mechanisms in electrodes
    (ΕΛΜΕΠΑ, Σχολή Μηχανικών (ΣΜΗΧ), ΔΠΜΣ Νανοτεχνολογία για Ενεργειακές Εφαρμογές, 2026-04-02) Daskalakis, Stylianos; Δασκαλάκης, Στυλιανός; Vernardou, Dimitra; Βερνάρδου, Δήμητρα
    Despite the high potential impact of aqueous battery systems, fundamental characteristics such as cost, safety, and stability make them less feasible for large-scale energy storage systems. Si is an attractive electrode material due to its high specific capacity. Nevertheless, it exhibits volume expansion during the intercalation/de-intercalation processes, leading to poor stability performance. Furthermore, carbon nanotubes have superior electro-conductivity and mechanical robustness, and consequently, they are extensively utilized in semiconductor, hydrogen storage, and flexible device research. Even though lithium-ion batteries have dominated the market, there are growing concerns about the limited availability of resources, high costs, and limited safety. Multivalent ion batteries have emerged as potential candidates due to their low cost, safety, energy density, and material reserves. Among the different multivalent metals, Zn has gained interest due to its high Zn/Zn2+ reversibility in aqueous environments. Due to their affordability, greater stability, and increased electrochemical performances, aluminum-ion batteries as possible post-lithium ion batteries are also appealing for large-scale electrochemical energy storage applications, such as grid-scale electric energy storage and electric cars. Hence, the target of the particular master dissertation is related with a. the development of nanocomposites based on Si with carbon nanotubes, to act as both mechanical support and electrical conductor, and b. promote an industrially competitive technology of aerosol-assisted chemical vapor deposition for a new class of material based on phenethylammonium bismuth iodide on fluorine doped SnO2-precoated glass substrate. In particular, the Si/CNT electrodes probed in ZnSO4 and Al2(SO4)3 electrolyte demonstrated a high discharge capacity of 170 mAh gSi-1at a high discharge plateau of ≈1.6 V, improved coulombic efficiency, cycling life, and stability. The intercalation/de-intercalation of Zn ions is limited for plain CNT, while, the Si-loaded electrodes show a larger integration area, indicating a higher energy storage capacity. The Si/CNT electrodes exhibited a semi-infinite diffusion or fast faradaic performance, with pseudocapacitive-dominated behavior in Zn2+. The primary range of diffusivity values of electrodes were 10-10 ~ 10-11 cm2 s–1 and 10-11 ~ 10-13 cm2 s–1 for the oxidation and reduction process, respectively. In Al3+, the electrodes displayed more faradaic-dominated performance with pseudocapacitor behavior, opposing to the electrodes in Zn2+. The results of the diffusion coefficient were in the range of 10-10 ~ 10-12 cm2 s–1, thus, verifying better ion mobility for Al3+. The Si/CNT electrode with the highest Si loading suggested the fastest Zn2+ and Al3+ mobility during the anodic and cathodic processes. Regarding the phenethylammonium bismuth iodide electrodes, they were electrochemically investigated in Zn2+ aqueous electrolytes presenting a specific capacity of 220 mAh g-1 at 0.4 A g-1 with excellent stability after 50 scans, capacity retention of almost 100%, and diffusion coefficient of 10-15 cm2 s–1 both in cathodic and anodic processes.