Preparation of sodium-ion-conductive Na_3−xSbS_4−xCl_x solid electrolytes

Abstract

Solid electrolytes have become important materials for improving the performance of next-generation all-solid-state sodium rechargeable batteries. Therefore, sodium vacancy doping for Na₃SbS₄ electrolytes was performed by partially substituting Cl for S. Na_3−xSbS_4−xCl_x electrolytes were prepared using a mechanochemical process and consecutive heat treatment. The structures, ionic conductivities, and air safety of the prepared Na_3−xSbS_4−xCl_x electrolytes were evaluated via X-ray diffraction and impedance, air stability, and electrochemical tests. The Na_2.9375SbS_3.9375Cl_0.0625 electrolyte showed a higher room-temperature ionic conductivity of 2.9 × 10⁻³ S cm⁻¹ than that of the Na₃SbS₄ electrolyte. An all-solid-state Na₁₅Sn₄/Na_2.9375SbS_3.9375Cl_0.0625/TiS₂ cell showed a reversible capacity of approximately 100 mA h g⁻¹ at room temperature. Thus, the Na_2.9375SbS_3.9375Cl_0.0625 solid electrolyte has the potential for application as a solid electrolyte in all-solid-state batteries.