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137 results on '"Nlebedim, Ikenna C."'

2. Lithium plating induced degradation during fast charging of batteries subjected to compressive loading

Author

Gargh, Prashant P., Sarkar, Abhishek, Nlebedim, Ikenna C., and Shrotriya, Pranav

Subjects
Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

We report the lithium plating associated capacity loss during fast charging of compressively loaded lithium-ion batteries (LIBs). The charging and discharging of LIB under compressive loading during service may affect the cell performance or initiate localized defects in the electrodes. Pouch cells of capacity 20mAh were compressively loaded to nominal pressures of 0-440 kPa and subjected to 10 cycles of fast charging at 1C and 4C. Experimental results show that cells charged at 4C-rate experienced significant capacity fade, and applying compressive loads exacerbated the capacity loss. The coulombic efficiency study shows that active lithium loss was higher for the initial cycles before gradually reducing to a minimal capacity loss for the tenth charging cycle. The cell voltage relaxation immediately after charging was monitored to identify the stripping of plated lithium after fast charging cycles and showed that the duration of lithium stripping was higher for cells under mechanical compressive loading. Scanning electron microscopy (SEM) and Electron paramagnetic resonance spectroscopy (EPR) characterization of the anode showed significantly higher lithium deposits on the anodes charged at a 4C rate under compressive loads. These results indicate that applied mechanical compression causes increased lithium plating during fast charging of batteries., Comment: Prepint of article submitted to Journal of Power Sources

Published
2023
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5. Pressure dependent magnetic properties on bulk CrBr3 single crystals

Author

Olmos, Rubyann, Alam, Shamsul, Chang, Po Hao, Gandha, Kinjal, Nlebedim, Ikenna C., Cole, Andrew, Tafti, Fazel, Zope, Rajendra, and Singamaneni, Srinivasa R.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The van der Waals class of materials offer an approach to two-dimensional magnetism as their spin fluctuations can be tuned upon exfoliation of layers. Moreover, it has recently been shown that spin-lattice coupling and long-range magnetic ordering can be modified with pressure in van der Waals materials. In this work, the magnetic properties of quasi two-dimensional CrBr3 are reported applying hydrostatic pressure. The application of pressure (0 - 0.8 GPa) shows a 72 % decrease in saturation magnetization with small decrease in the Curie temperature from 33 to 29 K. Density functional theory calculations with pressure up to 1 GPa show a reduction in volume and interplanar distance as pressure increases. To further understand magnetic properties with applied pressure, the magnetocrystalline anisotropy energy (MAE) and exchange coupling parameter (J) are calculated. There is minimal decrease in MAE and the first nearest neighbor interaction (J1) (U = 2.7 eV and J = 0.7 eV), shows an increase in J1 with respect to pressure. Overall, CrBr3 displays ferromagnetic interlayer coupling and the calculated exchange coupling and MAE parameters match well with the observations from the experimental work.

Published
2021

8. Reinvestigation of the intrinsic magnetic properties of (Fe$_{1-x}$Co$_x$)$_2$B alloys and crystallization behavior of ribbons

Author

Lamichhane, Tej Nath, Palasyuk, Olena, Antropov, Vladimir P., Zhuravlev, Ivan A., Belashchenko, Kirill D., Nlebedim, Ikenna C., Dennis, Kevin W., Jesche, Anton, Kramer, Matthew J., Bud'ko, Sergey L., McCallum, R. William, Canfield, Paul C., and Taufour, Valentin

Subjects
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Abstract

New determination of the magnetic anisotropy from single crystals of (Fe$_{1-x}$Co$_x$)$_2$B alloys are presented. The anomalous temperature dependence of the anisotropy constant is discussed using the standard Callen-Callen theory, which is shown to be insufficient to explain the experimental results. A more material specific study using first-principles calculations with disordered moments approach gives a much more consistent interpretation of the experimental data. Since the intrinsic properties of the alloys with $x=0.3-0.35$ are promising for permanent magnets applications, initial investigation of the extrinsic properties are described, in particular the crystallization of melt spun ribbons with Cu, Al, and Ti additions. Previous attempts at developing a significant hysteresis have been unsuccessful in this system. Our melt-spinning experiment indicates that this system shows rapid crystallization.

Published
2020
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10. Reinvestigation of the intrinsic magnetic properties of ( Fe 1 - x Co x ) 2 B alloys and crystallization behavior of ribbons

Author

Lamichhane, Tej Nath, Palasyuk, Olena, Antropov, Vladimir P, Zhuravlev, Ivan A, Belashchenko, Kirill D, Nlebedim, Ikenna C, Dennis, Kevin W, Jesche, Anton, Kramer, Matthew J, Bud’ko, Sergey L, McCallum, R William, Canfield, Paul C, and Taufour, Valentin

Subjects
Physical Sciences, Condensed Matter Physics, Temperature dependent anisotropy, Single crystals, Melt-spun ribbons, cond-mat.mtrl-sci, cond-mat.other, Materials Engineering, Mechanical Engineering, Applied Physics, Materials engineering, Condensed matter physics
Abstract

New determination of the magnetic anisotropy from single crystals of (Fe1-xCox)2B alloys are presented. The anomalous temperature dependence of the anisotropy constant is discussed using the standard Callen-Callen theory, which is shown to be insufficient to explain the experimental results. A more material specific study using first-principles calculations with disordered moments approach gives a much more consistent interpretation of the experimental data. Since the intrinsic properties of the alloys with x=0.3-0.35 are promising for permanent magnets applications, initial investigation of the extrinsic properties are described, in particular the crystallization of melt spun ribbons with Cu, Al, and Ti additions. Previous attempts at developing a significant hysteresis have been unsuccessful in this system. Our melt-spinning experiment indicates that this system shows rapid crystallization.

Published
2020

27. Coercivity of (Fe 0.7 Co 0.3) 2 B Nanowire and Its Bonded Magnet.

Author

Liu, Xubo and Nlebedim, Ikenna C.

Subjects
MAGNETIC anisotropy, MAGNETIC properties, CURIE temperature, PERMANENT magnets, REMANENCE, NANOWIRES
Abstract

(Fe0.7Co0.3)2B are potential permanent magnets material due to its large saturation magnetization and high Curie temperature. However, it has moderate magnetocrystalline anisotropy (MCA) and low coercivity. One way to improve its coercivity is to combine the contributions from magnetocrystalline- and magnetic-shape anisotropy by preparing (Fe0.7Co0.3)2B nanowires. We study the effects of size, morphology, and surface defects on the hard magnetic properties of nanowires using micromagnetic simulation. The hard magnetic properties of (Fe0.7Co0.3)2B nanowire-bonded magnets are estimated, including the role of inter-wire magnetostatic interaction. By considering the existence of local reductions in MCA energy of up to 30% on the surface layer of nanowires, the anisotropic bonded magnet with a 65% vol. of (Fe0.7Co0.3)2B nanowires would have typical remanence, Br= 7.6–8.4 kG, coercivity, Hci= 9.6–9.9 kOe, and maximum energy product, (BH)m = 14–17.8 MGOe. Developing effective technology for synthesizing nanowires and fabricating corresponding bonded magnets is promising for manufacturing practical magnets based on the magnetic phase with a relatively low or moderate MCA, such as (Fe0.7Co0.3)2B. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Thermal stability of anisotropic bonded magnets prepared by additive manufacturing.

Author

Gandha, Kinjal, Paranthaman, Mariappan Parans, Wang, Haobo, Liu, Xubo, and Nlebedim, Ikenna C.

Subjects
THERMAL stability, POLYPHENYLENE sulfide, MAGNETIC properties, HYBRID securities, REMANENCE, MAGNETS
Abstract

In this research, anisotropic NdFeB + SmFeN hybrid and NdFeB bonded magnets are additively printed in a polyphenylene sulfide (PPS) polymer binder. Printed NdFeB + SmFeN PPS bonded magnets displayed excellent magnetic properties (Br [remanence] = 6.9 kG [0.69 T], Hcj [coercivity] = 8.3 kOe [660 kA/m], and BHmax [energy product] = 9.9 MGOe [79 kJ/m3]) with superior corrosion resistance and thermal stability. The anisotropic NdFeB bonded magnet shows a high coercivity of 14.6 kOe (1162 kA/m) with a BHmax of 8.7 MGOe (69 kJ/m3). The coercivity and remanence temperature coefficients for NdFeB + SmFeN hybrid bonded magnets are −0.10%/K and −0.46%/K, and for NdFeB bonded magnets are −0.14%/K and −0.53%/K in the range of 300–400 K, indicating that the hybrid bonded magnets are thermally stable. The average flux aging loss for hybrid magnets was also determined to be very stable over 2000 h at 448 K (175°C) in air with 2.04% compared to that of NdFeB magnets with 3.62%. [ABSTRACT FROM AUTHOR]

Published
2023
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48. Reinvestigation of the intrinsic magnetic properties of(Fe1-xCox)2Balloys and crystallization behavior of ribbons

Author

Lamichhane, Tej Nath, primary, Palasyuk, Olena, additional, Antropov, Vladimir P., additional, Zhuravlev, Ivan A., additional, Belashchenko, Kirill D., additional, Nlebedim, Ikenna C., additional, Dennis, Kevin W., additional, Jesche, Anton, additional, Kramer, Matthew J., additional, Bud’ko, Sergey L., additional, McCallum, R. William, additional, Canfield, Paul C., additional, and Taufour, Valentin, additional

Published
2020
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