Understanding the role of aliovalent cation substitution on the li-ion diffusion mechanism in Li<sub>6+<i>x</i></sub>P<sub>1−<i>x</i></sub>Si<sub><i>x</i></sub>S<sub>5</sub>Br argyrodites
Tammo K. Schwietert, Ajay Gautam, Anastasia K. Lavrinenko, David Drost, Theodosios Famprikis, Marnix Wagemaker, Alexandros Vasileiadis
Abstract
substitution increases Li diffusion by activating Li occupancy in the T4 sites. Redistribution of Li-ions within the lattice results in a more uniform distribution of Li around the T4 and neighboring T5 sites, flattening the energy landscape for diffusion. Since the T4 site is positioned in the intercage jump pathway, an increase in the intercage jump rate is found, which is directly related to the macroscopic diffusion and bulk conductivity. Analysis of neutron diffraction experiments confirms partial T4 site occupancy, in agreement with the computational findings. Understanding the aliovalent substitution effect on interstitials is crucial for improving solid electrolyte ionic conductivity and advancing solid-state battery performance.