Abstract
This work continues our systematic study of Li-and Mn-rich cathodes for lithium-ion batteries. We chose Li2MnO3 as a model electrode material with the aim of correlating the improved electrochemical characteristics of these cathodes initially activated at 0°C with the structural evolution of Li2MnO3, oxygen loss, formation of per-oxo like species (O22−) and the surface chemistry. It was established that performing a few initial charge/discharge (activation) cycles of Li2MnO3 at 0°C resulted in increased discharge capacity and higher capacity retention, and decreased and substantially stabilized the voltage hysteresis upon subsequent cycling at 30°C or at 45°C. In contrast to the activation of Li2MnO3 at these higher temperatures, Li2MnO3 underwent step-by-step activation at 0°C, providing a stepwise traversing of the voltage plateau at >4.5 V during initial cycling. Importantly, these findings agree well with our previous studies on the activation at 0°C of 0.35Li2MnO3·0.65Li[Mn0.45Ni0.35Co0.20]O2 materials. The stability of the interface developed at 0°C can be ascribed to the reduced interactions of the per-oxo-like species formed and the oxygen released from Li2MnO3 with solvents in ethylene carbonate–methyl-ethyl carbonate/LiPF6 solutions. Our TEM studies revealed that typically, upon initial cycling both at 0°C and 30°C, Li2MnO3 underwent partial structural layered-to-spinel (Li2Mn2O4) transition.
Original language | English |
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Article number | 4388 |
Pages (from-to) | 1-22 |
Number of pages | 22 |
Journal | Materials |
Volume | 13 |
Issue number | 19 |
DOIs | |
State | Published - 1 Oct 2020 |
Bibliographical note
Publisher Copyright:© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Funding
Acknowledgments: A part of the work discussed herein was supported by the Israeli Prime Minister’s Office and by the Israeli Committee for Higher Education within the framework of the INREP project. B.M. and F.A.S. thank Daniela Kovacheva from Bulgarian Academy of Science for her helpful suggestions on the synthesis of Li2MnO3 and Ronen Y. Tirrer from Electronics Unit, Bar-Ilan University for technical support and valuable suggestions. Funding: A.I.F. was funded by the U. S. National Science Foundation Grant number DMR-1911592. BL2-2 beamline operations were supported in part by the Synchrotron Catalysis Consortium (U.S. DOE, Office of Basic Energy Sciences, Grant No. DE-SC0012335).
Funders | Funder number |
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Israeli Committee for Higher Education | |
Israeli Prime Minister’s Office | |
Office of Basic Energy Sciences | DE-SC0012335 |
Synchrotron Catalysis Consortium | |
U. S. National Science Foundation | DMR-1911592 |
U.S. DOE |
Keywords
- Bulk and surface characteristics
- Decreased the voltage hysteresis
- Layered-to-spinel transition
- Li-and Mn-rich materials
- LiMnO activation at 0°C
- Lithium-ion batteries
- Stabilized cycling