Fast Ag-Ion-Conducting GeS2–Sb2S3–AgI Glassy Electrolytes with Exceptionally Low Activation Energy

Silver-ion-sconducting solid electrolytes with low activation energy are important because of their distinctive application potential in solid-state batteries operated within a broad temperature range, especially below room temperature. Achieving glassy solid electrolytes with high ionic conductivity, low activation energy, and good thermal stability is a continuous challenge for the design and synthesis of novel fast ion-conducting glasses. Here, we report markedly low activation energy and high room-temperature ionic conductivity in melt-quenched GeS2–Sb2S3–AgI chalcogenide glasses. Homogeneous 2.5GeS2–27.5Sb2S3–70AgI glass presenting high glass transition temperature of 135 °C shows high ionic conductivity of 9.18 × 10–3 S/cm at 25 °C and low activation energy of 0.07 eV, which is the lowest among those of Ag-ion glassy electrolytes. Structural characterization by using Raman spectra suggests that, in the disordered network structure of GeS2–Sb2S3–AgI glasses, the formation of chain fragments composed by [SbS3–x I x ] n , which is similar to the double chain of [(SbSI)∞]2 in the SbSI crystal structure, provides possible diffusion pathways to facilitate low-barrier concerted migration of silver ions.