Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Nanohybridization of POM/CNT Anode Materials for Enhanced Cycle Stability and Superior Discharge Capacity in Sodium-Ion Batteries(Elsevier Science SA, 2025) Chilufya, Langson; Bugday, Nesrin; Yasar, Sedat; Emirdag-Eanes, MehtapPolyoxometalates (POMs) have emerged as high-energy-density electrodes acting as 'electron/ion sponges' for pseudocapacitive energy storage, attributed to their swift and reversible multi-redox reactions. In sodium-ion batteries (SIBs), POM-based electrodes have given excellent energy density. However, the negligible conductivity of pristine POMs and high electrolyte dissolution can lead to subpar electrochemical performance in poor capacity retention, and rate capability. To address these challenges, we employed a facile ultrasonication strategy to prepare polyoxometalate/carbon-nanotube (POM/CNT) nanohybrids. CNTs were modified with the tetrabutylammonium polyoxotungstate, TBA3[PW12O40].nH2O (TBA-PW12), yielding TBA-POM/CNT nanohybrids. These were synthesized using four CNT sources: single-walled (SW), multi-walled (MW), and their hydroxyl-functionalized analogues (SWOH and MWOH). The nanohybrids were characterized using FT-IR, Raman spectroscopy, powder XRD, TGA, SEM/EDX, STEM, XPS, and BET analysis. Electrochemical evaluation of TBA-PW12/SW and TBA-PW12/MW nanohybrids as an anode for SIB showed superior Na-ion storage, delivering reversible capacities of 69.4 mAh g-1 and 27.5 mAh g-1, respectively, at a current density of 2 A g-1 after 1000 cycles. Under the same conditions, the nanohybrids from functionalized SWOH and MWOH also showed enhanced performance, achieving discharge capacities of 66.2 mAh g-1 and 57.3 mAh g-1, respectively. This impressive electrochemical performance was ascribed to the multiple active sites of TBA-PW12 combined with conductive pathways and surface functionalities of CNTs, which enable rapid electron transfer, high Na-ion conductivity, and efficient ion diffusion. Overall, POM/CNT nanohybridization presents a promising strategy to overcome the intrinsic limitations of pristine POMs, thereby advancing the design of high-performance anodes for SIBs and sustainable energy applications.Article Citation - WoS: 11Citation - Scopus: 13Magnesium-Ion Battery Anode From Polymer-Derived Sioc Nanobeads(Wiley, 2023) Guo, Wuqi; Kober, Delf; Gurlo, Aleksander; Bekheet, Maged F.; İçin, Öykü; Ahmetoğlu, Çekdar VakıfTin-containing silicon oxycarbide (SiOC/Sn) nanobeads are synthesized with different carbon/tin content and tested as electrodes for magnesium-ion batteries. The synthesized ceramics are characterized by thermogravimetric-mass spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, N2 sorption analysis, scanning electron microscope, energy-dispersive X-ray, and elemental analysis. Galvanostatic cycling tests, rate performance tests, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) tests, and ex situ XRD measurements are conducted. Results of battery performance tests present a high capacity of 198.2 mAh g-1 after the first discharging and a reversible capacity of 144.5 mAh g-1 after 100 cycles at 500 mA g-1. Excellent rate performance efficiency of 85.2% is achieved. Battery performances in this research are influenced by surface area, and tin contentof the SiOC/Sn nanobeads. EIS, CV tests, and ex situ XRD measurements reveal that higher surface area contributes to higher capacity by providing more accessible Mg2+ ion storage sites and higher rate capability by improving the diffusion process. Higher Sn content increases battery capacity through reversible Mg-Mg2Sn-Mg alloying/dealloying process and improves the rate performances by increasing electrical conductivity. Besides, SiOC advances cycling stability by preventing electrode collapse and enhances the capacity due to higher surface capacitive effects. SiOC nanobeads containing Sn nanoparticles are synthesized and tested as anode for magnesium-ion batteries. The anodes show high performance with reversible capacity of 144.5 mAh g-1 after 100 cycles at 500 mA g-1 and excellent rate performance efficiency of 85.2% from 50 to 500 mA g-1.image