First-Principles Computational Studies on Li-Ion Battery Cathode Materials

First-principles computation methods play an important role in designing and developing new electrode materials for Li-ion batteries (LIBs). These methods are more useful to study phase transformations, electron and ion mobility processes, and transportation kinetics related to various Li-intercalated materials and investigate mechanisms underlying in the electrochemical/lithium intercalation processes [1-3].

We have examined the influence of Mn substitution by Ni on the structural, electronic, and Li-intercalation properties of LiMn₂O₄spinel and also identified potential layered cathode material for LIBs by performing first-principles computational studies. The calculations were performed in the local density aproximation (LDA) to density-functional theory (DFT) as implemented in the Vienna Ab Initio Simulation Package (VASP). In order to reduce the number of the plane waves required for simulating the interactions between ions and electrons, ultra-soft Vanderbilt pseusopotentials were used.

In the case of spinel cathode materials, Ni substitution was done systematically for up to 25% by replacing Mn in a Mn₁₆O₃₂ supercell configuration and then Li atoms were intercalated. The influence of Ni substitution on the lithium hoping pathways between the two stable Li positions was studied and Li⁺ diffusion pathway in the Ni-substituted Mn-O supercell structures was identified. The calculations revealed that Ni substitution for Mn in LiMn₂O₄ indeed improved Li ion mobility [4].

To identify potential layered cathode materials for LIBs, first-principles calculations in conjunction with alloy metal method were used to evaluate average voltage, phase stability, formation energy, and Li intercalation potential for a series of layered LiMO₂ (M = Co, Ni, Mn, and W) systems. According to the negative formation energy (-0.0535 eV), average voltage (3.48 V), and similar phase stability upon lithium extraction compared to LiCoO₂, we concluded LiNi_0.66Co_0.17Mn_0.17O₂as a promising layered cathode material for lithium-ion batteries [5]. Computational details and results on the spinel and layered cathode materials will be presented in detail.

References

1) G. Ceder, Y.-M. Chiang, D.R. Sadoway, M.K. Aydinol, Y.-I. Jang and B. Huang, Nature392 (1998) 694.

2) G. Ceder, MRS Bulletin35 (2010) 693.

3) Y.S. Meng and M. Elena Arroyo-de Dompablo, Energy Environ. Sci.2 (2009) 589.

4) R. Singhal, J.J. Saavedra-Arias, R. Katiyar, Y. Ishikawa, M.J. Vilkas, S.R. Das, M.S. Tomar  and R.S. Katiyar, J. Renewable Sustainable Energy1 (2009) 023102.

5) J.J. Saavedra-Arias, C.V. Rao, J. Shojan, A. Manivannan, L. Torres, Y. Ishikawa and R.S. Katiyar, J. Power Sources 211 (2012) 12.