Why superionic conductor can be optimized by thermal quenching

Increase of Li ion conductivity in argyrodites by freezing anion site-disorder

2020/12/28 by K. Albe

In this joined work with W. Zeiers group (WWU Münster), we demonstrate synthetic control over the anion site-disorder in Li6 PS4Br. Site-disorder can be tailored by subjecting the material to different temperatures followed by quenching. Neutron powder diffraction and AIMD simulations show that changing site-disorder results in diferences in the local charges, which in turn directly affects the lithium distribution. A higher degree of site-disorder means more spatially distributed Li and shorter Li–Li distances responsible for the intercage jumps. The optimized site-disorder can subsequently lead to a fourfold increase of the ionic conductivity. This work provides a better understanding of how synthesis and post synthesis conditions affect the structure and the ionic transport in lithium argyrodites. This knowledge is a stepping-stone for engineering materials properties without changing the composition of the material itself.