Molecular Dynamics Simulations on Li-Ion Conduction in Nasicon-Type Solid Electrolytes

As a promising solid electrolyte material for all-solid-state Li-ion batteries (LIBs), Na super ionic conductor (NASICON)-type material is considered to be comparable to perovskite-type or garnet-type ionic conductors. Since the discovery of the fast Na-ion conducting NASICON-type material of Na1+xZr2SixP3-xO12 in 1976 [1], many kinds of Li-ion conducting NASICON-type solid electrolytes have been investigated. One of the most popular among them is Li1+xAlxTi2-x(PO4)3 (LATP), which can be generated by partially substituting Ti4+ with Al3+ in LiTi2(PO4)3 (LTP). Especially, LATP with x = 0.3 exhibits enhanced bulk Li-ion conductivity in the order of 10-3 S/cm at room temperature [2,3]. However, it is also well known that LTP-based materials react with Li metal at around 2.5 V vs. Li+/Li due to the Ti4+/Ti3+ redox reaction [4,5]. Recently, another NASICON-type solid electrolyte LiZr2(PO4)3 (LZP) has been well studied, then it is known to be stable in contact with Li metal due to no redox reaction up to 5.5 V [6]. Therefore, NASICON-type materials would be alternative solid electrolytes for all-solid-state LIBs. In this study, we estimate Li-ion conductivity and activation energy in NASICON-type solid electrolytes using molecular dynamics simulations. The Li-ion trajectory is also analyzed and discussed. The results and discussions will be shown in more detail in our presentation. Acknowledgements This work was supported by the “Materials research by Information Integration” Initiative (MI2I) project of the Support Program for Starting Up Innovation Hub from Japan Science and Technology Agency (JST). References [1] J. B. Goodenough, H. Y.-P. Hong, and J. A. Kafalas, Mat. Res. Bull. 11, 203-220 (1976). [2] H. Aono, E. Sugimoto, Y. Sadaoka, N. Imanaka, and G. Adachi, J. Electrochem. Soc. 136, 590-591 (1989). [3] H. Aono, E. Sugimoto, Y. Sadaoka, N. Imanaka, and G. Adachi, J. Electrochem. Soc. 137, 1023-1027 (1990). [4] C. Delmas and A. Nadiri, Mater. Res. Bull. 23, 65-72 (1988). [5] S. Patoux and C. Masquelier, Chem. Mater. 14, 5057-5068 (2002). [6] Y. Li, W. Zhou, X. Chen, X. Lü, Z. Cui, S. Xin, L. Xue, Q. Jia, and J. B. Goodenough, Proc. Natl. Acad. Sci. 113, 13313-13317 (2016).