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9. Poly (vinyl alcohol) based carbon nanofibers as freestanding anodes for lithium-ion batteries

Author

Pampal, Esra Serife, Stojanovska, Elena, Kilic, Ali, and Demir, Ali

Subjects
Raman spectroscopy -- Electric properties -- Analysis, Batteries -- Analysis -- Electric properties, Electrical conductivity -- Analysis -- Electric properties, Infrared spectroscopy -- Electric properties -- Analysis, Engineering and manufacturing industries, Science and technology
Abstract

In this study, we investigated the iodination process for the preparation of water-soluble polyvinyl alcohol (PVA)-based carbon nanofibers (CNFs) and their electrochemical properties. Iodinated nanofibers were carbonized at different temperatures (600[degrees]C, 800[degrees]C) under an argon (Ar) atmosphere. Morphology and physical properties of fiber mats were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and thermogravimetric analysis (TGA), while electrical conductivity measurements were done using four probes. As a freestanding anode in half-cell lithium batteries, the CNFs were prepared by electrospinning of PVA and PVA-CNT blend, which was exposed to iodine vapor at various temperatures (60, 80, and 100[degrees]C). Iodine vapor treatment at 80[degrees]C and subsequent carbonization at 800[degrees]C provided a 29% carbon yield. The resulting CNT-containing optimized CNFs exhibited superior flexibility, electrical conductivity (2.16 S/cm), and handleability, making them a promising, binder-free environmentally friendly carbon source for lithium-ion batteries with high capacity (672 mAh/g at 50 mA/g). The study clearly showed that PVA might be an alternative precursor for the production of carbon micro- and nanofibers. Highlights * Anodic performance of PVA-based carbon nanofibers was analyzed. * PVA precursor offers economic and environmental option for binder-free electrodes. * PVA-CNT composite nanofibers with optimized iodination and carbonization time identified as a promising high carbon yield carbon source for lithium-ion batteries. * CNT-containing optimized carbon nanofibers exhibited superior flexibility and electrical conductivity (2.16 S/cm). * Freestanding fiber anodes exhibited a higher capacity of 672 mAh/g, at 50 mA/g compared to conventional graphite anode (372 mAh/g). KEYWORDS carbon nanofiber, iodination, Lithium-ion battery, polyvinyl alcohol, 1 | INTRODUCTION Nanofibers are versatile engineering materials due to their high surface area and adjustable porosity. Their potential applications were extended to many fields, not only textiles but also [...]

Published
2024
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13. Fine Porous Structures Fabricated Using Laser Powder Bed Fusion of Ti–6Al–4 V

Author

Sanchez, Salome, Zafari, Ahmad, Demir, Ali Gökhan, Caprio, Leonardo, Previtali, Barbara, Holynska, Malgorzata, Gibson, Ian, Jafari, Davoud, de Amorim Almeida, Henrique, Series Editor, Al-Tamimi, Abdulsalam Abdulaziz, Editorial Board Member, Bernard, Alain, Editorial Board Member, Boydston, Andrew, Editorial Board Member, Koc, Bahattin, Editorial Board Member, Stucker, Brent, Editorial Board Member, Rosen, David W., Editorial Board Member, de Beer, Deon, Editorial Board Member, Pei, Eujin, Editorial Board Member, Gibson, Ian, Editorial Board Member, Drstvensek, Igor, Editorial Board Member, de Ciurana, Joaquim, Editorial Board Member, Lopes da Silva, Jorge Vicente, Editorial Board Member, da Silva Bártolo, Paulo Jorge, Editorial Board Member, Bibb, Richard, Editorial Board Member, Alvarenga Rezende, Rodrigo, Editorial Board Member, Wicker, Ryan, Editorial Board Member, Pal, Snehashis, editor, and Ihan Hren, Nataša, editor

Published
2024
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14. Challenges and Opportunities for Laser Applications in Electric Vehicle Manufacturing

Author

Demir, Ali Gökhan, Kriegler, Johannes, Fortunato, Alessandro, Caprio, Leonardo, Geiger, Christian, Hille, Lucas, Kick, Michael Karl, Ascari, Alessandro, Liverani, Erica, Zaeh, Michael F., Chaari, Fakher, Series Editor, Gherardini, Francesco, Series Editor, Ivanov, Vitalii, Series Editor, Haddar, Mohamed, Series Editor, Cavas-Martínez, Francisco, Editorial Board Member, di Mare, Francesca, Editorial Board Member, Kwon, Young W., Editorial Board Member, Trojanowska, Justyna, Editorial Board Member, Xu, Jinyang, Editorial Board Member, Carrino, Luigi, editor, Galantucci, Luigi Maria, editor, and Settineri, Luca, editor

Published
2024
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15. Conventional and Innovative Aspects of Bespoke Metal Implants Production

Author

Ginestra, Paola, Piccininni, Antonio, Demir, Ali Gökhan, Chaari, Fakher, Series Editor, Gherardini, Francesco, Series Editor, Ivanov, Vitalii, Series Editor, Haddar, Mohamed, Series Editor, Cavas-Martínez, Francisco, Editorial Board Member, di Mare, Francesca, Editorial Board Member, Kwon, Young W., Editorial Board Member, Trojanowska, Justyna, Editorial Board Member, Xu, Jinyang, Editorial Board Member, Carrino, Luigi, editor, Galantucci, Luigi Maria, editor, and Settineri, Luca, editor

Published
2024
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16. Mini-crush or Nano-crush Stenting Technique for Complex Coronary Bifurcation Lesions: the Multicenter MINANO Registry

Author

Uzun, Fatih, Güner, Ahmet, Serin, Ebru, Alizade, Elnur, Çizgici, Ahmet Yaşar, Doğan, Abdullah, Çetin, İlyas, Deniz, Muhammed Furkan, Serter, Berkay, Uysal, Hande, Tanık, Veysel Ozan, Demir, Ali Rıza, Panç, Cafer, Keskin, Kudret, Püşüroğlu, Hamdi, Şahin, İrfan, Serbest, Nail Güven, Gök, Saner Bahadır, Bedir, Fatih Furkan, Akarsu, Taner, Yalçın, Ahmet Arif, and Aktürk, İbrahim Faruk

Published
2025
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25. Familial Mediterranean fever: perspective on female fertility and disease course in pregnancy from a multicenter nationwide network

Author

Yurdakul, Fatma Gül, Bodur, Hatice, Çay, Hasan Fatih, Uçar, Ülkü, Keskin, Yaşar, Sargın, Betül, Gürer, Gülcan, Yurdakul, Ozan Volkan, Çalış, Mustafa, Deveci, Hülya, Aydın, Yıldıray, Hizmetli, Sami, Çevik, Remzi, Karahan, Ali Yavuz, Ataman, Şebnem, Duruöz, Mehmet Tuncay, Ecesoy, Hilal, Günendi, Zafer, Toprak, Murat, Şen, Nesrin, Altıntaş, Duygu, Cengiz, Ahmet Kıvanç, Çağlayan, Gökhan, Demir, Ali Nail, Kaplan, Hüseyin, Ketenci, Sertaç, Alkan Melikoğlu, Meltem, Nayimoğlu, Mehmet, Nas, Kemal, Sarıfakıoğlu, Banu, and Sezer, İlhan

Published
2023
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28. On the inverse problem of identifying an unknown coefficient in a space-time fractional differential equation

Author

Bayrak, Mine Aylin and Demir, Ali

Subjects
Mathematics - Analysis of PDEs
Abstract

In this study, we focus on identifying solution and an unknown space-dependent coefficient in a space-time fractional differential equation by employing fractional Taylor series method. The substantial advantage of this method is that we don't take any over-measured data into account. Consequently, we determine the solution and unknown coefficient more precisely. The presented examples illustrate that outcomes of this method are in high agreement with the exact ones of the corresponding problem. Moreover, it can be implemented and applied effectively comparing with other methods.

Published
2021

29. Interplay between powder catchment efficiency and layer height in self-stabilized laser metal deposition

Author

Donadello, Simone, Furlan, Valentina, Demir, Ali Gökhan, and Previtali, Barbara

Subjects
Physics - Applied Physics
Abstract

In laser metal deposition (LMD) the height of the deposited track can vary within and between layers, causing significant deviations during the process evolution. Previous works have shown that in certain conditions a self-stabilizing mechanism occurs, maintaining a regular height growth and a constant standoff distance between the part and the deposition nozzle. Here we analyze the link between the powder catchment efficiency and the deposition height stability. To this purpose, a monitoring system was developed to study the deposition in different process conditions, using inline measurements of the specimen weight in combination with the layer height information obtained with coaxial optical triangulation. An analytical model was used to estimate the deposition efficiency in real-time from the height monitoring and the process parameters, which was verified by the direct mass measurements. The results show that the track height stabilization is associated to a reduction of the powder catchment efficiency, which is governed by the melt pool relative position with respect to the powder cone and the laser beam. For a given set of parameters, the standoff distance can be estimated to achieve the highest powder catchment efficiency and a regular height through the build direction.

Published
2021
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38. Time-resolved quantification of plasma accumulation induced by multi-pulse laser ablation using self-mixing interferometry

Author

Donadello, Simone, Finazzi, Valentina, Demir, Ali Gökhan, and Previtali, Barbara

Subjects
Physics - Plasma Physics, Physics - Applied Physics
Abstract

In this work a method based on self-mixing interferometry (SMI) is presented for probing the concentration of plasma plumes induced by multi-pulse laser ablation. An analytical model is developed to interpret the single-arm interferometric signal in terms of plasma electron number density. Its time dependence follows a power-law scaling which is determined by concurrent effects of plume accumulation and propagation. The model has been applied for the experimental study of plume formation at variable laser pulse frequencies on different materials. The plume expansion dynamics has been observed with high-speed imaging, and the SMI measurements allowed for a time-resolved estimation of the electron number density. The intrinsic advantages of the SMI technique in terms of robustness and low intrusiveness would allow for its usage as a fast diagnostic tool for the dynamical scaling of laser-induced plumes. Moreover it can be easily applied in laser-based manufacturing technologies where plasma concentration monitoring and control is important.

Published
2020
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