Visualizing lithium-ion migration pathways in battery materials

Abstract

The understanding of lithium-ion migration through the bulk crystal structure is crucial in the search for novel battery materials with improved properties for lithium-ion conduction. In this paper, procrystal calculations are introduced as a fast, intuitive way of mapping possible migration pathways, and the method is applied to a broad range of lithium-containing materials, including the well-known battery cathode materials LiCoO2, LiMn 2O4, and LiFePO4. The outcome is compared with both experimental and theoretical studies, as well as the bond valence site energy approach, and the results show that the method is not only a strong, qualitative visualization tool, but also provides a quantitative measure of electron-density thresholds for migration, which are correlated with theoretically obtained activation energies. In the future, the method may be used to guide experimental and theoretical research towards materials with potentially high ionic conductivity, reducing the time spent investigating nonpromising materials with advanced theoretical methods. The path of least resistance: Procrystal analysis is introduced as a new tool to aid in the search for novel crystalline materials for battery applications. The simple analysis enables fast calculations with an appealing visual result. The method has been applied to a wide range of materials, including LiCoO2, LiMn 2O4, and LiFePO4 (see figure) and compared qualitatively to various theoretical and experimental analyses. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.