Probing Li ion dynamics in amorphous xLi ₂ SO ₄ ⋅(1 − x)LiPO ₃ by quasielastic neutron scattering

The diffusion dynamics of a series of lithium sulfate substituted phosphate glass materials xLi ₂ SO ₄ ⋅(1 − x)LiPO ₃ has been probed by quasielastic neutron scattering. Amorphous Li ion conductors are attractive as electrolyte materials for all-solid state batteries because they are highly isotropic and chemically stable. Local disorder is expected to reduce barriers to ion migration – leading to improved ionic conductivity relative to their crystalline counterpart – while minimizing unwanted electron transport. We report Li self-diffusion in these materials on a length scale comparable to the interatomic spacings, obtaining values D ≃ 55 ± 4 × 10 ⁻⁸ cm ² /s at 450 K. Elastic neutron scattering measurements show an alteration of the phosphate chain backbone of the glass material.