Co-sputtered thin films of silver-ion-conductive GeS2-Sb2S3-AgI solid electrolytes

Abstract

Fast silver-ion-conducting chalcogenide glassy electrolyte thin films demonstrate remarkable application potential in miniaturized solid-state energy storage devices. However, the application of Ag-based film cell is retarded by the lack of large-scale film fabrication method. Thus, this study employs magnetron co-sputtering, a technique amenable to large-scale production, to fabricate GeS₂-Sb₂S₃-AgI glassy electrolyte films, with AgI incorporation fraction modulated by sputtering power to tailor the microstructure and ion transport characteristics. Systematic characterization reveals that AgI incorporation promotes the formation of SbSI/SbI₃-like structures within the amorphous matrix, thereby triggering the reconstruction of the chalcogenide network. Adjusting the sputtering power of AgI to 8 W, the thin films exhibit a dense amorphous state and achieve an optimal room-temperature conductivity of 5.32 × 10⁻⁴ S cm⁻¹. Further increase in sputtering power triggers columnar film growth, disrupting the structural continuity and causing a two-order conductivity drop. Silver nanoparticles have been electroplated onto the electrolyte films by a scanning probe electrochemical deposition experiment, confirming the lateral migration capability of Ag⁺ ions within the films. This work could provide vital understanding of fabrication of glassy electrolyte films.