Regulating the Uniform Na Deposition Behavior Using Atomically Dispersed Fe-Doped Mesoporous Carbon Nanospheres for High-Performance Sodium Metal Batteries

Sodium metal batteries (SMBs) are attracting intensive attention as an appealing candidate for high-energy-density batteries, owing to the high specific capacity, rich abundance, and low cost of metallic sodium (Na). However, the practical application of SMBs has been greatly hindered by the uncontrollable dendrite growth and unstable solid electrolyte interfaces, which are responsible for the poor Na stripping/plating reversibility and short lifespan. Herein, we report an atomically dispersed Fe-doped mesoporous carbon nanosphere (Fe-MCN) as a sodiophilic host for facilitating homogeneous Na nucleation and deposition behaviors. Benefitting from the advantages of uniform mesoporous structures with large surface areas and atomically dispersed Fe doped in the carbon nanospheres, low nucleation barriers and subsequent homogeneous deposition behavior of Na metal are achieved, which give rise to highly reversible stripping/plating performance and outstanding cycling stability. As a result, the Na||Cu cell based on Fe-MCN-modified Cu substrates exhibits outstanding electrochemical performance with a high Coulombic efficiency of 99.97% over 850 cycles, and an ultralong cycling lifespan of 2600 h at 1 mA cm–2 and 1 mA h cm–2 is demonstrated by the symmetric cell with Na@Fe-MCN@Cu anodes. Moreover, the Na3V2(PO4)3 full cell based on the Na@Fe-MCN@Cu anode guarantees outstanding cycling stability for 2000 cycles with a capacity retention as high as 84%, showing high potential in the practical application of SMBs.