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Selected Works of Santosh KC
Article
First Principles Study of Li-Site Doping Effect on the Properties of LiMnO2 and Li2MnO3 Cathode Materials
ECS Transactions (2015)
  • Fantai Kong, University of Texas at Dallas
  • Roberto C. Longo, The University of Texas at Dallas
  • Dong-Hee Yeon, Samsung Electronics
  • Jaegu Yoon, Samsung Electronics
  • Jin-Hwan Park, Samsung Electronics
  • Chaoping Liang, The University of Texas at Dallas
  • Santosh KC, The University of Texas at Dallas
  • Seok-Kwang Doo, Samsung Electronics
  • Kyeongjae Cho, The University of Texas at Dallas
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Abstract
Due to a high voltage of 4.6 V and large practical capacity of ~260 mAh/g, the over-lithiated-oxides (OLOs) which are often represented as Li2MnO3·LiMO2 (M = Mn, Co, Ni), have been intensely investigated as a promising candidate of the next generation cathode materials for Li-ion battery. The Li2MnO3 composite structure plays an important role in providing high capacity and phase stability to the system. However, during cathode charge-discharge operation, Li2MnO3 is unstable and partly transforms into LiMnO2, indicating that the phase used in practice has mixed both Li2MnO3 and LiMnO2. In this work, the effects of Li-site doping from 10 cationic dopants (Mg, Ti, V, Nb, Fe, Ru, Co, Ni, Cu, Al) on the electrochemical properties of both oxides are studied using density functional theory. The calculations show that, comparing with the Mn-site doped phases, Li-site doping is thermodynamically unstable for the ground states, but the small transition barriers can be easily overcome under high thermal fluctuations during the realistic cathode synthesis process. The redox potentials of both oxides can be lowered by most of the Li-site dopants. For example, Nb strongly lowers the redox potential of the LiMnO2 phase, and Ru shows an unexpected effect on the Li2MnO3 phase: it activates the Li atoms in the Li-layer and, at the same time, it immobilizes the Li atoms in the Li-Mn mixed-layer by increasing the redox potential. These results support the experimental observations about Li-site doping and provide an explanation about the effects of Li-site doping on the electrochemical properties.
Disciplines
Publication Date
2015
DOI
10.1149/06422.0021ecst
Citation Information
Fantai Kong, Roberto C. Longo, Dong-Hee Yeon, Jaegu Yoon, et al.. "First Principles Study of Li-Site Doping Effect on the Properties of LiMnO2 and Li2MnO3 Cathode Materials" ECS Transactions Vol. 64 Iss. 22 (2015) p. 21 - 32
Available at: http://works.bepress.com/santosh-kc/25/