Weak Correlation between the Polyanion Environment and Ionic Conductivity in Amorphous Li–P–S Superionic Conductors

Amorphous Li–P–S
materials have been widely used
as solid-state electrolytes for all-solid-state batteries because
of their high ionic conductivity (10–4 to 10–3 S cm–1) as well as good synthetic
accessibility and processability. Despite the potential of these materials,
their amorphous structures have made it challenging to quantify the
relation between the structure and conductivity. In this paper, we
use ab initio molecular dynamics simulations to investigate the role
of the local structure and density in determining the conductivity
of amorphous Li–P–S structures with different polyanion
units. We observe similar rates for Li-ion hopping regardless of the
local P–S polyanion environment in these amorphous materials,
indicating that the path connectivity at a larger length scale may
be controlling the overall Li conductivity. This finding will serve
as an important guideline in the continued development of amorphous
solid electrolytes for advanced all-solid-state batteries.