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8. Imaging the coherent propagation of collective modes in the excitonic insulator Ta2NiSe5 at room temperature.

Author

Bretscher, Hope M., Andrich, Paolo, Yuta Murakami, Golež, Denis, Remez, Benjamin, Telang, Prachi, Singh, Anupam, Harnagea, Luminita, Cooper, Nigel R., Millis, Andrew J., Werner, Philipp, Sood, A. K., and Rao, Akshay

Subjects
*CONDENSED matter physics, *EXCITON theory, *DISCRETE symmetries, *COMPUTATIONAL physics, *BOSE-Einstein condensation, *MATHEMATICAL physics, *SUPERCONTINUUM generation
Published
2021
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12. Composition Optimization of Layered Lithium Nickel Manganese Cobalt Oxide Materials Synthesized via Ultrasonic Spray Pyrolysis.

Author

Lengyel, Miklos, Xiaofeng Zhang, Atlas, Gal, Bretscher, Hope L., Belharouak, Ilias, and Axelbaum, Richard L.

Subjects
OXIDES, LITHIUM, ELECTROCHEMISTRY, PYROLYSIS, ELECTRIC properties
Abstract

Lithium-rich, layered composites of xLi2MnO3 ⋅ (1-x)Li(Ni1/3Mn1/3Co1/3)O2were synthesized via spray pyrolysis to identify the chemistry yielding optimal electrochemical performance for materials produced by this method. The x values selected for optimization were x = 0.3, 0.5, 0.7, equivalent to Li1.14Mn0.46Ni0.2Co0.2O2, Li1.2Mn0.54Ni0.13Co0.13O2 and Li1.26Mn0.6Ni0.07Co0.07O2, respectively. The materials were annealed at 850°C or 900°C for 2 hours, and then tested in coin cells. Li1.2Mn0.54Ni0.13Co0.13O2annealed at 900°C displayed the best electrochemical performance with excellent capacity retention, displaying a reversible capacity of 236 mAhg-1after 100 cycles when cycled between 2.0-4.8 V at C/10 rate, where 1C = 280 mAg-1. The cycling profiles display voltage fade, presumably due to a layered-spinel phase transformation. The synthesis method leads to high purity and excellent uniformity at the nanoscale, and the materials have less voltage fade compared to similar materials produced by co-precipitation. Voltage fade is more pronounced when the upper cut-off voltage is 4.8 V, as opposed to 4.6 V. A decrease in the Li2MnO3 content of the material reduces voltage fade, such that x = 0.3 (or Li1.14Mn0.46Ni0.2Co0.2O2) shows the best structural stability over cycling. [ABSTRACT FROM AUTHOR]

Published
2014
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