Solid-state materials with high ionic conduction are necessary to many technologies including all-solid-state Li-ion batteries. Understanding how crystal structure dictates ionic diffusion is at the root of the development of fast ionic conductors. Here, we show that LiTi2(PS4)3 exhibits a Li-ion diffusion coefficient about an order of magnitude higher than current state-of-the-art lithium superionic conductors. We rationalize this observation by the unusual crystal structure of LiTi2(PS4)3 which offers no regular tetrahedral or octahedral sites for lithium to favorably occupy. This creates a smooth, frustrated energy landscape resembling more the energy landscapes present in liquids than in typical solids. This frustrated energy landscape leads to a high diffusion coefficient combining low activation energy with a high pre-factor.
@article{arxiv.1708.02997,
title = {Superionic diffusion through frustrated energy landscape},
author = {D. Di Stefano and A. Miglio and K. Robeyns and Y. Filinchuk and M. Lechartier and A. Senyshyn and H. Ishida and S. Spannenberger and D. Prutsch and S. Lunghammer and D. Rettenwander and M. Wilkening and B. Roling and Y. Kato and G. Hautier},
journal= {arXiv preprint arXiv:1708.02997},
year = {2019}
}