Fluorinated porous frameworks enable robust anode-less sodium metal batteries

Sodium metal batteries hold great promise for energy-dense and low-cost energy storage technology but are severely impeded by catastrophic dendrite issue. State-of-the-art strategies including sodiophilic seeding/hosting interphase design manifest great success on dendrite suppression, while neglecting unavoidable interphase-depleted Na⁺ before plating, which poses excessive Na use, sacrificed output voltage and ultimately reduced energy density. We here demonstrate that elaborate-designed fluorinated porous framework could simultaneously realize superior sodiophilicity yet negligible interphase-consumed Na⁺ for dendrite-free and durable Na batteries. As elucidated by physicochemical and theoretical characterizations, well-defined fluorinated edges on porous channels are responsible for both high affinities ensuring uniform deposition and low reactivity rendering superior Na⁺ utilization for plating. Accordingly, synergistic performance enhancement is achieved with stable 400 cycles and superior plateau to sloping capacity ratio in anode-free batteries. Proof-of-concept pouch cells deliver an energy density of 325 Watt-hours per kilogram and robust 300 cycles under anode-less condition, opening an avenue with great extendibility for the practical deployment of metal batteries.