Sodiophilic Fe/Na anodes enabling dendrite-free sodium metal batteries with ultralong cycle life

Sodium metal anodes hold great promise for next-generation high-energy batteries, yet practical deployment is hindered by severe dendrite growth and unstable electrode/electrolyte interfaces. Herein, we report a facile one-step rolling strategy to fabricate Fe/Na anodes, in which Fe nanoparticles are uniformly incorporated into the Na matrix to serve as sodiophilic nucleation sites. Structural analyses confirm the high purity, uniform dispersion, and improved surface integrity of the Fe/Na electrodes. Electrochemical measurements reveal a markedly reduced nucleation overpotential and enhanced charge-transfer kinetics, with a low activation energy of 26.87 kJ mol^-1 compared to pure Na (43.48 kJ mol^-1). As a result, Fe/Na||Fe/Na symmetric cells deliver exceptional cycling stability (850 h at 0.1 mA cm^-2 and 600 h at 0.5 mA cm^-2), while full cells coupling Na₃V₂(PO₄)₃ cathodes exhibit excellent rate capability (73.7 mAh g^-1 at 10 C) and long-term retention (81% after 240 cycles at 5 C). Mechanistic investigations reveal that Fe incorporation effectively suppresses dendrite formation by promoting uniform Na deposition. This work provides both experimental and kinetic insights into alloy-based Na anodes, offering a scalable and cost-effective strategy for high-power, dendrite-free sodium metal batteries.