Mega High Utilization of Sodium Metal Anodes Enabled by Single Zinc Atom Sites.

Low utilization of active metallic sodium (Na) and uncontrollable growth of Na dendrites remain significant challenges for high-performance Na metal batteries, which are limited to inefficient Na utilization (<1%) and shallow cycling conditions (0.25-1.0 mAh cm-2). In this work, a kind of Na metal anode with record-high utilization and long-term cycling stability is reported, using carbon-substrate-supported nitrogen-anchored zinc (Zn) single atoms as a current collector. Single Zn atom sites which serve as a strong "magnet" for Na ions, can guide the metallic Na uniform nucleation and free from dendrite-induced short circuit. The nucleation overpotential of our strategy is essentially zero, where most of the reported modified substrates were greatly exceed 20 mV. Specifically, the Na anodes exhibit a high Na stripping/plating Coulombic efficiency with 99.8% over 350 cycles and a stable voltage response with small voltage hysteresis after cycling 1000 h. The full cell exhibits high Na utilization up to 100% and superior long-term cycling stability for more than 1000 cycles with excellent capacity retention. In terms of lifetime and Na utilization, the Na metal anodes based on our strategy significantly outperforms the reported state-of-the-art Na metal anodes. Moreover, this affords new insights into the controllable Na nucleation behavior and high Na utilization and sheds fresh light on atomic level design of an electrode for Na metal anodes.