Aqueous-solution synthesis of Na3SbS4 solid electrolytes for all-solid-state Na-ion batteries

Room-temperature-operable all-solid-state Na-ion batteries (ASNBs) using sulfide Na-ion solid electrolytes (SEs) are promising because of their potential for greater safety, lower cost, and acceptable performance. Despite extensive developments in the area of sulfide Na-ion SEs, their poor chemical stability and prospects for wet-chemical synthesis have been overlooked to date. Herein, the scalable synthesis of Na3SbS4 via aqueous-solution routes using precursors of Na2S, Sb2S3, and elemental sulfur for ASNBs is described. With no concerns about the evolution of toxic H2S gas, the aqueous-solution-synthesized Na3SbS4 exhibits high ionic conductivities (0.1-0.2 mS cm(-1) at 25 degrees C). Importantly, the homogeneity of the aqueous solutions enables the creation of uniform Na3SbS4 coatings on FeS2. Fe2S/Na-Sn ASNBs, employing the aqueous-solution-synthesized Na3SbS4 and the Na3SbS4-coated FeS2 for the SE layer and positive electrode, respectively, demonstrate a high charge capacity of 256 or 346 mA h g(-1) with good reversibility at 30 degrees C, highlighting their potential for practical applications.This research was supported by the Technology Development Program to Solve Climate Changes of the National Research Foundation (NRF) funded by the Ministry of Science & ICT (No. 2017M1A2A2044501), and by the Materials and Components Technology Development Program of MOTIE/KEIT (10077709)