In:
ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2014-04, No. 2 ( 2014-06-10), p. 427-427
Abstract:
The over-lithiated-oxides (OLOs), a composite of layered structures of Li 2 MnO 3 and LiMO 2 (M = Mn, Fe, Co, Ni), have shown much higher storage capacity than the traditional layered oxides for Li ion battery cathode because of the Li 2 MnO 3 phase. However, Li 2 MnO 3 is not stable after the 1st charge-discharge cycle and will partly transform into layered LiMnO 2 , which indicates that the practically used phase is a mixture of both Li 2 MnO 3 and LiMnO 2 . During the subsequent cycles, the OLO voltage decreases due to the phase transition of layered LiMnO 2 into spinel. Experimentally, the effective dopants satisfying multiple cathode materials requirements of thermodynamic stability, optimized voltage and improved kinetics based on ionic and electronic conductivities are investigated to overcome the voltage degradation and to improve the power capacity. In this work, redox potential, lithium ion diffusion and charge carrier transportation of both phases are examined in details using the ab initio density-functional theory (DFT) simulations. The calculations find, due to the Jahn-Teller effect of Mn 3+ atoms, Li vacancy migration in LiMnO 2 has special behaviors and hole polaron and electron polaron will form in LiMnO 2 and Li 2 MnO 3 phases, respectively. Based on the understanding of the pure phase properties, the effects of 10 cationic (Mg, Ti, V, Nb, Fe, Ru, Co, Ni, Cu, Al) and 2 anionic (N, F) dopants on the redox potential, ionic and electronic conductivity are investigated. These DFT findings could provide conceptual guidance in the experimental search for the effective dopants enabling the practical application of OLO cathodes. This work was supported by Samsung GRO project.
Type of Medium:
Online Resource
ISSN:
2151-2043
DOI:
10.1149/MA2014-04/2/427
Language:
Unknown
Publisher:
The Electrochemical Society
Publication Date:
2014
detail.hit.zdb_id:
2438749-6
Permalink