The search for an ideal solid electrolyte for a safe, long-lasting all-solid battery has been extenstive, but the fundamentals of lithium diffusion are still not completely understood. One of the fastest electrolyte that has been found in lithium germanium thiophosphate, though is electrolyte cannot be used in batteries due to instability with the electrodes. While significant computational research has been done on LGPS, nuances of the mechanisms are still unknown. Insight into the extraordinary conductivity of LGPS, will enable the engineering and search for new electrolyte materials.

Polarization of anions and tetrahedral moieties and rotation analysis were studied in order to elucidate the conductivity difference in LGPS and LPS solid electrolytes. LPS has orders of magnitude lower conductivity than LGPS, but a very similar composition and structure. These analyses allow quantification of the effect of electronic structure and correlated motion on lithium diffusion. Polarization and rotation events were extracted from Density Functional Theory Molecular Dynamics (DFT-MD) simulations. Detailed analysis of the MD simulations revealed that the interaction of lithium with the lattice affects diffusion through the polarization and rotation of the tetrahedral anions. The GeS₄ behaves differently than the PS₄, which increases the diffisivity in LGPS compared to LPS.