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

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