Browsing by Author "Kadirgama, K"

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    Interfacial synergy of pre-lithiation silicon anodes and GNP/MnO2/S cathodes for lithium polysulfides in silicon-sulfur batteries studied via DFT
    Aslfattahi, N; Kiai, MS; Karatas, D; Baydogan, N; Samylingam, L; Kadirgama, K; Kok, CK
    The development of innovative electrodes with outstanding high-rate cycling performance for the next generation of sulfur-based batteries has emerged as a key area of research. This study presents a straightforward approach for designing silicon/graphene nanoplates as an anode material using a one-step hydrothermal process. Additionally, to reduce the shuttle effect, the GNP/MnO2/S cathode is investigated. In this study, MnO2 particles are grown in situ on the surface of the GNP. The pre-lithiation Si/GNP anode and the MnO2/GNP/S and GNP/S cathodes are evaluated at a current density of 1000 mA g-1. The findings reveal an impressive capacity retention of 1048 mA h g-1 after 200 cycles, indicating remarkable cycling performance for the cell with the pre-lithiation Si/GNP anode and the MnO2/GNP/S cathode. The capacity retention observed in thicker electrodes highlights the synergistic effect of the effective chemical absorption of lithium polysulfides by MnO2/GNP/S when used as sulfur hosts. Additionally, DFT calculations suggest that MnO2 has a significant tendency to adhere to the surface of polysulfides, aligning well with our findings regarding cycle performance, rate performance, and discharge capacity. The novel electrode configuration introduced in this study provides a novel pathway for the large-scale production of high-performance pre-lithiation Si-S batteries.
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    The Development and Experimental Analysis of Freestanding Single-Walled Carbon Nanotube/Sulfur Composite Cathode for the Next Generation of Sulfur-Based Batteries
    Kiai, MS; Aslfattahi, N; Karatas, D; Baydogan, N; Samylingam, L; Kadirgama, K; Kok, CK
    This work uses a solution-based and scalable method to provide a freestanding single-walled carbon nanotube (SWCNT)/S cathode in both Li-S and Na-S batteries. SWCNTs with high conductivity and surface area can enhance the cathode flexibility. The incorporation of oxygen and sulfur bonds can enhance active redox sites for chemical adsorption. Sulfur and oxygen effectively hinder the shuttle effect by improving chemical interactions between the polysulfides and the nonpolar carbon framework, leading to improved cyclability of Na-S and Li-S cells. The cycling stability plots of Na-S and Li-S batteries with freestanding SWCNT/S as a cathode are investigated for 150 cycles at a high current density of 1000 mA g-1. Both cells display a stable capacity behavior during cycling. The discharge capacity of the Li-S cell with the SWCNT/S cathode is retained at 978.2 mAh g-1 while the Na-S cell only shows the capacity retention of 769.4 mAh g-1 after 150 cycles. Coulombic efficiencies of approximate to 94% and 90% are observed for Li-S and Na-S cells respectively. Therefore, the SWCNT/S cathode in both Li-S and Na-S batteries hinders the polysulfide shuttle, providing high electrolyte diffusion, resulting in improved active material reutilization and minimized capacity fading. Freestanding SWCNT/S cathode can enhance cycling stability over long-term cycling and is proved to be a promising cathode in both Li-S and Na-S batteries.