1. Heteroatom-synergistic effect on anchoring polysulfides In chalcone-linked nanographene covalent organic frameworks for high-performance Li─S batteriesKayaramkodath C. Ranjeesh, Bharathkumar H. Javaregowda, Safa Gaber, Preeti Bhauriyal, Sushil Kumar, Tina Škorjanc, Matjaž Finšgar, Thomas Heine, Kothandam Krishnamoorthy, Dinesh Shetty, 2025, original scientific article Abstract: Lithium-sulfur (Li─S) batteries are an attractive option for future energy storage devices because they offer higher theoretical specific capacity, energy density, and cost-effectiveness than commercial lithium-ion batteries. However, the practical applications of Li─S batteries are significantly limited by the shuttle effect caused by intermediate lithium polysulfides (LiPSs) and slow redox kinetics. In this study, the molecular engineering of chalcone-linked, sp2-bonded nanographene-type covalent organic frameworks (COFs) as sulfur hosts is reported to enhance interactions with LiPSs, thereby effectively suppressing the shuttle effect. The developed sulfur-hosting cathode material demonstrated outstanding battery performance, surpassing most reported materials by achieving a specific capacity of 1228 mA h g−1 at 0.5C, with 80% retention after 500 cycles and an average Coulombic Efficiency (C.E.) of 99%. Additionally, the mechanisms of sulfur immobilization, the subsequent conversion into lithium polysulfides (LiPSs), and their binding energies with COFs are investigated using density functional theory (DFT) calculations. These findings offer valuable insights into the structure-property relationships essential for developing more efficient sulfur-hosting cathodes.
Keywords: covalent organic frameworks, lithium-sulfur battery, nanographene, anion-pi interaction, polysulfide shuttle
Published in DKUM: 17.03.2025; Views: 0; Downloads: 5
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2. The development of ARM-based portable and adaptable power supply : magistrsko deloTomislav Brlek, 2019, master's thesis Abstract: This master’s thesis describes a development of a portable and adjustable power supply. The first part of the thesis introduces us to the working principle of power supplies in general. Next, we present a functional design of a portable and adjustable power supply and a list of its required functionalities. Chapter “switched-mode power supplies” introduces us to the theoretical basics of the said power supplies, while chapter “linear regulators” introduces us to different types of linear regulators and tells us more about how they work. Everything regarding which microcontroller was used and why it was used is described in the “ARM microcontroller” chapter. Besides microcontrollers, it also talks about which integrated development environment is used and how the microcontroller is programmed. A full and detailed description of each part of the analog circuitry can be found in the chapter “describing the development of the portable and adjustable power supply”. Lastly, the user interface is described in detail.
Keywords: portable power supply, ARM processor, variable laboratory bench power supply, LCD touchscreen, energy efficient, lithium battery, battery charger, voltage control
Published in DKUM: 13.11.2019; Views: 1164; Downloads: 153
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