Effects of Aliovalent Doping on Structure and Properties of Na₃SbS₄ Type Superionic Conductors

Aliovalent doping is a promising strategy to further enhance the ionically conductive properties of solid-state ion conductors. Beside the conductivity, the aliovalent dopants also affect the synthesis mechanism, crystalline structure, as well as the electrochemical stability of the doped conductors. In this talk, we will present Na₃SbS₄ as a model material to introduce different types of aliovalent anion or cation dopants, and discuss the doping chemistry in sulfide-based solid electrolytes. On the structural studies, we tracked the synthetic process of doped Na₃SbS₄ by in situ neutron diffraction and examined the phase purity and structural stability after different doping treatment. Besides, we also evaluated the ionic conductivity of doped Na₃SbS₄ conductors and established the correlations between dopants and ion transport, as well as the interface stability between the doped Na₃SbS₄ conductors with metallic Na anode. We will also discussion a few strategies for interface stabilization in sulfide-based solid state Na batteries.