First-Principles Based Modeling of Li-Metal/Solid-Electrolyte Interfaces in Application to Li-Batteries

All solid-state batteries could store significantly higher energy compared to conventional lithium-ion batteries using liquid electrolytes, simultaneously highly increase the safety. They are promising for future wide applications, such as wearable device, phones and even electric cars. However, several critical issues (e.g. low conductivity of solid electrolyte, mechanical and chemical stabilities of interfaces etc.) need to be solved before commercialization of all solid-state batteries. The knowledge of the fundamental aspects of these issues would highly accelerate the process of searching and designing the advanced materials and structures for efficient and low cost all solid-state batteries. The interfacial interactions are complicate and difficult to characterize experimentally. There is insufficient understanding of the interface formation processes and factors affecting interfacial structures, charge transfer and ion transport, chemical and mechanical stability and degradation. We use first-principles based methods, such as QM and ReaxFF [1] reactive molecular dynamics (MD) to achieve better understanding of these problems. A family of sulfide ceramics, so-called Li-argyrodites, Li₆PS₅X (X = Cl, Br, I), shows high ionic conductivity (~7 · 10⁻³ S/cm at 298 K) [2] and might be considered as a possible candidate for solid electrolyte for Li-batteries. These materials can provide a balance of efficiency and price. We have built the Li₆PS₅Cl structure and Li/Li₆PS₅Cl interface and performed QM MD and ReaxFF MD simulations on this systems. The results of these simulations will be reported together with results obtained for some other interface systems of interest.

 

Acknowledgements. This work was financially supported by Bosch Energy Research Network Grant No. 13.01.CC11.

References

[1]   A.C.T. van Duin, .C.T., S. Dasgupta, F. Lorant, W.A. Goddard III “ReaxFF: A Reactive Force Field for Hydrocarbons” J. Phys. Chem. A 105,9396-9409, 2001.

[2]   H.-J. Deiseroth, S.-T. Kong, H. Eckert, J. Vannahme, C. Reiner, T. Zaiβ, M. Schlosser ”Li₆PS₅X: A class of crystalline Li-rich solids with an unusually high Li⁺ mobility” Angew. Chem. Int. Ed. 47, 755-758, 2008.