physica status solidi (a)
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Editor: Stefan Hildebrandt (Editor-in-Chief), Sabine Bahrs (Deputy Editor)
Online ISSN: 1862-6319
Front Cover: High power lithium ion battery materials by computational design (Phys. Status Solidi A 8/2011)
Empirical bond length – bond valence relations provide insight into the link between structure of and ion transport in solid electrolytes and mixed conductors. Building on their earlier systematic adjustment of bond-valence (BV) parameters to the bond softness, Adams and Rao (pp. 1746–1753) discuss how the squared BV mismatch is linked to the absolute energy scale and is used as a general Morse-type interaction potential for analyzing the low-energy ion migration paths in ion conducting solids or mixed conductors by either an energy landscape approach or molecular dynamics (MD) simulations. The cover image shows in the background examples from the wide range of lithium oxides for which ion transport pathways have been studied in this work, revealing significant differences to an earlier geometric approach. The novel BV-based force-field has then been applied to investigate a range of mixed conductors, focusing on cathode materials for lithium ion battery (LIB) applications to promote a systematic design of LIB cathodes. As an example the cover image shows on the left hand side the Li ion effect of a FeLi/LiFe antisite defect on the Li ion trajectory for a MD simulation of LiFePO4 (red and blue indicate two layers). Here as in many cases the MD simulation will yield a trajectory only for unphysically high temperatures (here 1000 K) or extremely long simulation times, while a BV-based analysis shows the energy landscape for the mobile Li and the relevant paths from snapshots of the room temperature simulation (right image).