Sathiya, M. and Ramesha, K. and Rousse, G. and Foix, D. and Gonbeau, D. and Prakash , A.S. and Doublet, M.L. and Hemalatha, K. and Tarascon, J.M. (2013) High Performance Li2Ru1−yMnyO3 (0.2 ≤ y ≤ 0.8) Cathode Materials for Rechargeable Lithium-Ion Batteries: Their Understanding. Chemistry of Materials, 25. pp. 1121-1131. ISSN 0897-4756

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Understanding the origin of the high capacity displayed by Li2MnO3−LiMO2 (M = Ni, Co) composites is essential for improving their cycling and rate capability performances. To address this issue, the Li2Ru1−yMnyO3 series between the iso-structural layered end-members Li2MnO3 and Li2RuO3 was investigated. A complete solid solution was found, with the 0.4 ≤ y ≤ 0.6 members showing sustainable reversible capacities exceeding 220 mAh·g−1 centered around 3.6 V vs Li+/Li. The voltage−composition profiles display a plateau on the first charge as compared to an S-type curve on subsequent discharge which is maintained on the following charges/discharges, with therefore a lowering of the average voltage. We show this profile to evolve upon long cycling due to a structural phase transition as deduced from XRD measurements. Finally we demonstrate, via XPS measurements, the oxidation and reduction of ruthenium (Ru5+/Ru4+) during cycling together with a partial activity of the Mn4+/Mn3+ redox couple. Moreover, we provide direct evidence for the reversibility of the O2− → O− anionic process upon cycling, hence accounting for the high capacity displayed by these materials. This work, by capturing the main redox processes pertaining to these materials, should facilitate their development

Item Type: Article
Uncontrolled Keywords: Li2MnO3, high voltage cathodes, Li-ion battery, oxide ion hole
Subjects: Lithium batteries
Electrochemical Power Sources
Depositing User: Dr. N Meyyappan
Date Deposited: 05 Jan 2015 04:45
Last Modified: 05 Jan 2015 04:45

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