Regulating Sodium Deposition through Gradiently‐Graphitized Framework for Dendrite‐Free Na Metal Anode

Abstract Na metal anode (NMA) is one of the most promising candidate materials for next‐generation low‐cost sodium metal batteries. However, the preferred deposition of Na metal at the anode/separator interface increases the risk of dendrite penetration of the separator, consequently, reduces safety and life of batteries with NMA. In this study, a Na deposition‐regulating strategy is shown by designing a gradiently graphitized 3D carbon fiber (CF) framework as host (grad‐CF), whereby Na is guided to deposit preferentially at the bottom of the anode, safely away from the separator. The obtained Na anode significantly reduces the probability of dendrite‐induced short circuits. The grad‐CF host enables NMA stable cycling at a high current density of 6 mA cm −2 . When the Na@grad‐CF is applied as anode in full cells pared with Na 3 V 2 (PO 4 ) 3 (NVP) cathode, it exhibits a reversible capacity of 73 mA h g −1 after 500 cycles with a low decay rate of 0.13%.