In-Situ formation Inorganic/Organic solid electrolyte interphase and sodium affinity sites for improved sodium metal anodes

Due to the severe dendrite phenomenon, the large-scale application of sodium metal batteries (SMBs) is difficult. The fabrication of artificial inorganic/organic solid electrolyte interphases (SEI), incorporating the role of metallic sites in addressing the dendrite issue, has attracted great attention. This work reports the in-situ formation of inorganic/organic SEI and sodium affinity sites from antimony-doped zinc fluoride current collector (Sb-ZnF₂@Zn). The resulting Sb-ZnF₂@Zn/Na anodes exhibited dendrite-free sodium deposition, significantly enhanced electrochemical performance, and improved long-term stability by optimizing the interfacial composition and structure. Thanks to the formed inorganic/organic SEI and sodium affinity sites, the symmetrical cells displayed an extended cycle life of 2000 h at 6 mA cm⁻² with 3mAh cm⁻². This work not only improves the uniform infiltration of the electrolyte but also promotes the uniform transport of Na⁺, as validated by dynamic contact angle experiments and finite element calculations. The findings provide valuable insights into the design of advanced sodium metal anodes for next-generation SMBs.