Tailoring Sodium Anodes for Stable Sodium–Oxygen Batteries

Sodium–oxygen batteries based on abundant sodium resource have caused increasing interest due to their high energy density and low cost. However, the reactive sodium anode always induces unpredictable side reactions especially in oxygen atmosphere and battery short circuit due to the uncontrolled formation of dendrites. Here, an accessible method to grow a durable protective passivation film on the surface of sodium anodes is reported. The sodium fluoride‐rich film efficiently suppresses O2 crossover and electrolyte decay related side reactions on sodium anodes. Significantly, no dendrites form during long‐term stripping/plating cycles. Benefiting from these superiorities, sodium–oxygen batteries achieve impressive improvement of discharge–charge ability and reliable safety. These results enrich the approaches for stabilizing sodium anodes and allow researchers to focus on the investigations on the air cathode and the overall chemistry of sodium–oxygen batteries.