Guiding Sodium Deposition through a Sodiophobic–Sodiophilic Gradient Interfacial Layer for Highly Stable Sodium Metal Anodes

Na metal anodes have shown great promise for a low cost energy storage system but its practical application is hampered by the uncontrollable dendrite growth. Here, we present a sodiophobic–sodiophilic gradient interfacial layer to regulate the Na plating/stripping behavior by decorating Ag particles with a concentration gradient along the thickness of a carbon nanotube (CNT) film. This gradient interfacial layer is light in weight, mechanically robust and can guide Na deposition on the Ag-rich, sodiophilic region far away from the separator but next to the current collector, which effectively prevents the formation of Na dendrites. The gradient interfacial layer allows the Na metal anode to work at a reversible capacity of 8 mA h cm–2 at a current density of 8 mA cm–2 with a long lifespan of 1000 h. Our work provides a facile and efficient approach for guiding Na deposition and offers promise for application in practical Na metal batteries.