Neutron scattering studies of ionic conducting amorphous xLi₂SO₄(x-1)LiPO₃

We have probed the structure and dynamics of a series of lithium sulfate substituted phosphate glass materials (xLi₂SO₄(x-1)LiPO₃) using elastic, quasielastic, and inelastic neutron scattering. Glass-based 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 have conducted quasielastic neutron scattering measurements in order to determine the self-diffusion in these materials on a lengthscale comparable to the interatomic spacings, obtaining values ~5x10^-7 cm²/s at 450K. The addition of Li₂SO₄ is known to improve the conduction properties in the LiPO₃ glasses. We will discuss the structural and dynamic changes that occur within the Li₂SO₄ solubility range x≤0.6.