Effect of excess Li sub(2)S on electrochemical properties of amorphous li sub(3)ps sub(4) films synthesized by pulsed laser deposition

Amorphous Li sub(3)PS sub(4) films were synthesized by pulsed laser deposition (PLD) at room temperature using Li sub(3)PS sub(4) targets with excess lithium and sulfur. Raman and X-ray photoemission spectroscopies indicated that the Li sub(3)PS sub(4) film synthesized with a stoichiometric amount of Li sub(3)PS sub(4) target contained lithium-deficient phases such as Li sub(4)P sub(2)S sub(6), Li sub(2-x)S and sulfur due to composition deviation caused during the ablation process. The film synthesized with a 14% Li sub(2)S-excess target (Li sub(3.42)PS sub(4.21)) contained fewer impurities, and exhibited a higher ionic conductivity of 5.3 10 super(-4) S/cm at 298 K than the lithium-deficient film (3.1 10 super(-4) S/cm). The target composition is an important factor for the fabrication of highly conductive Li sub(3)PS sub(4) films for electrolytes in thin-film batteries.