An Implantable Artificial Protective Layer Enables Stable Sodium Metal Anodes

Sodium metal anodes are commonly limited by low Coulombic efficiency and an unstable interface between Na metal and carbonate ester electrolytes. Herein, a freestanding and implantable artificial protective layer with strong mechanical rigidity is reported as a feasible strategy to suppress the dendrite and stabilize the interface, which realizes a high Coulombic efficiency of similar to 96% in a carbonate-based electrolyte. Furthermore, the freestanding implantable protective layer enables good cycling performance for the sodium metal battery with only 300% Na metal anode excess under high voltage. This work highlights the importance of the rational design of the interface for high-voltage sodium metal batteries.