In situ construction of a stable interface induced by the SnS2 ultra-thin layer for dendrite restriction in a solid-state sodium metal battery

Abstract

The interface issue between Na and the NASICON solid electrolyte is recognized as the dominant reason for the growth of Na metal dendrites. In this work, aSnS₂ ultra-thin layer is fabricated on the surface of the Na₃Zr₂Si₂PO₁₂ electrolyte by a fast (1 min) and convenient (air atmosphere) pyrolysis method. A mixed-ion-electron conductor layer consisting of Na–Sn alloy and Na₂S constructed in situ through the reaction between the Na metal anode and SnS₂ can not only build a continuous and tight bonding interface between Na₃Zr₂Si₂PO₁₂ and Na, but also realize the uniform and rapid transfer of charge and Na⁺ flux at the interface, resulting in a stable interface during the Na deposition/stripping process. The Na symmetric cell with a maximum current density of 0.9 mA cm⁻² can be stably operated at 0.1–0.4 mA cm⁻² with low overpotential for a long time at room temperature. The Na₃V₂(PO₄)₃|Na₃Zr₂Si₂PO₁₂–SnS₂|Na solid-state battery delivers excellent capacity retention ratios and rate performance, profiting from the constructed stable interface. This work proposes a facial strategy for the improvement of interface design, driving the application of inorganic solid electrolyte in solid-state batteries.