Sodiophilic Au/reduced-graphene-oxide for dendrite free sodium metal anode

In this work, a nanocomposite composed of gold nanoparticles (NPs) supported by reduced graphene oxide (Au/ rGO) is designed and synthesized via a simple chemical bath reaction method at room temperature followed by post annealing treatment. Au/rGO is further employed as the host of sodium metal anode with a dendrite free morphology, demonstrated by ex-situ scanning electron microscopy (SEM) and in-situ optical microscopy characterization. As a result, Au/rGO electrode exhibits a small overpotential of 3.5 mV at a current density of 2 mA cm-2 with a specific capacity of 2 mAh cm-2. Meanwhile, it can stably cycle for 400 h at a high current density of 5 mA cm-2 with an areal capacity of 1 mAh cm-2. Detailed studies indicate that the excellent electrochemical performance is mainly owing to the sodiophilic surface enabled by Au NPs, guiding the Na metal uniform deposition, thus effectively inhibiting the sodium dendrite formation. Finally, as a proof of concept, a full battery composed of Na@Au/rGO as the anode and Na3V2(PO4)3@C as the cathode is assembled and delivers a capacity of 93.9 mAh g-1 at 100 mA g-1 after 180 cycles. Our work proves that Au/rGO is a promising host for sodium metal anode.