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.