Enhancing ionic conductivity in Ag₃PS₄ via mechanical amorphization

Amorphous conductors with high ionic conductivity are a promising candidate as electrolytes in all-solid state batteries. In this work, we prepared amorphous Ag ₃PS ₄ conductor via a chemo-mechanical milling process, and then characterized its structure and electrochemical properties. The results show that Ag ⁺ conductivity of the amorphous Ag ₃PS ₄ was remarkably enhanced by three orders of magnitude compared to its crystalline counterpart. Furthermore, the amorphous sample exhibits lower activation energy (E _a) for ionic conductivity as a function of temperature. Structural characterizations indicate that the tetrahedral [PS ₄] units were retained in amorphous Ag ₃PS ₄, but the Ag ⁺ ions became more liberated than those in the crystalline state, leading to the enhanced migration of Ag ⁺ ions, thereby, the ionic conductivity in amorphous Ag ₃PS ₄ is drastically increased. This work provides insight into the crucial role of the disorder in raising the ionic conductivity of amorphized chalcogenide materials containing mobile ions.