Dipole-dipole interaction-induced dense primitive solid-electrolyte interphase for high-power Ah-level anode-free sodium metal batteries

High-energy and resource-abundant anode-free sodium metal batteries suffer from limited lifespan owing to dendrite growth and rapid capacity fading at early stages, particularly at high rate and high capacity. Here we report a preliminary surface-passivation strategy by highly fluorinated electrolyte, instantly forming a dense inorganic-dominant primitive solid-electrolyte interphase. Driven by dipole-dipole interaction, the spontaneously formed solid-electrolyte interphase is sufficiently dense to resist solvent decomposition and moisture attack, meanwhile regulating Na plating/stripping at high current densities and areal capacities up to 8 mA cm-2 and 5 mAh cm-2, respectively. The fabricated anode-free batteries demonstrate long-term stability at high cathode loadings (10–15 mg cm-2) and high rates (1–3 C), even with moisture contained. Impressively, fast-charging Ah-level anode-free pouch cells deliver energy density up to 150 Wh kg-1 (0.5 C) based on total cell weight, achieving power density as high as 152 W kg-1 and long lifespan up to 700 cycles at 1 C. Anode-free sodium batteries promise high energy at low cost but suffer from short lifespans. Here, authors develop a fluorinated electrolyte that forms a robust interphase, enabling fast-charging pouch cells with high energy density and stable cycling even under harsh conditions.