Space-Confined Guest Synthesis to Fabricate Sn-Monodispersed N-Doped Mesoporous Host toward Anode-Free Na Batteries

Severe issues including volume change and dendrite growth on sodium metal anodes hinder the pursuit of applicable high-energy-density sodium metal batteries. Herein, an in situ reaction approach is developed that takes metal-organic frameworks as nano-reactor and pore-former to produce a mesoporous host comprised of nitrogen-doped carbon fibers embedded with monodispersed Sn clusters (SnNCNFs). The hybrid host shows outstanding sodiophilicity that enables rapid Na infusion and ultralow Na nucleation overpotential of 2 mV. Its porous structure holds a high Na content and guides uniform Na deposition. Such host provides favorable Na plating/stripping with an average Coulombic efficiency of 99.96% over 2000 cycles (at 3 mA cm^-2 and 3 mA h cm^-2 ). The Na-infused SnNCNF anode delivers extreme Na utilization of 86% in symmetric cells (at 10 mA cm^-2 and 10 mA h cm^-2 ), outstanding rate capability and cycle life in Na-SnNCNF||Na₃ V₂ (PO₄ )₃ full cells (at 1 A g^-1 for over 1000 cycles with capacity retention of 92.1%). Furthermore, high-energy/power-density anode-less and anode-free Na cells are achieved. This work presents an effective heteroatom-doping approach for fabricating multifunctional porous carbon materials and developing high-performance metal batteries.