Structural insight and modulating of sulfide-based solid-state electrolyte for high-performance solid-state sodium sulfur batteries

Room-temperature (RT) solid-state sodium-sulfur batteries (SSNSBs) are one of the most promising next-generation energy storage systems because of their high energy density, enhanced safety, cost-efficiency, and non-toxicity. While most of the studies for SSNSBs focused on designing and developing sulfur cathodes, we carve out a new path to understanding and modulating the structures and properties of sulfide solid-state electrolytes (SSEs) for achieving high-performance SSNSBs. A novel cation and anion co-doped approach was developed to enhance the ionic conductivity and expand the electrochemical stability of sulfide SSEs, and eventually improve the electrochemical performance of SSNSBs. The crystal structure and local structure of the cation/anion co-doped sulfide SSEs have been studied in detail combined with the density functional theory (DFT) calculations for mechanism understanding. SSNSBs incorporating co-doped sulfide SSEs demonstrate high capacity and stable cycling performance, even at high rates, which is at the top of the reported performances in the literature. Our novel approach for cation and anion-tuned SSEs demonstrates excellent ionic conductivity and electrochemical stability, paving a new way for the next generation of solid-state sodium batteries.