Solid state K-ion conducting electrolytes are key elements to address the current problems in K batteries. Here, we propose a sulfide K-ion conductor K3SbS4 with a low activation energy of 0.27 eV and a promising 2-dimensional K migration pathway. W doped-K3-xSb1-xWxS4 (x=0.04, 0.06, 0.08, 0.10 and 0.12) compounds were also reported with increasing vacancy concentration and improved ionic conductivity. Among them, K2.92Sb0.92W0.08S4 exhibits a maximum room temperature (20 °C) conductivity of 7.7×10-5 S/cm in a sintered body and 1.4×10-4 S/cm at 40 °C, which is remarkably high for a potassium ion conductor at ambient temperature.

Sulfide based potassium solid state electrolytes with low activation energy

ACS Spring 2022

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