Conformal Sodium Deposition Facilitated by Ion Adsorption‐Intercalation Process within Hetero‐Interface for Stable Sodium Metal Batteries

Abstract Sodium (Na) metal battery is regarded as one of the most promising candidates for large‐scale energy storage devices, benefiting from the abundant sodium reserves and low cost. However, its practical application is hindered by the dendrite growth and unstable electrode‐electrolyte interface. Herein, a 3D sodiophilic structure composed of a carbon matrix overlaid with g ‐C 3 N 4 coating layers ( g ‐C 3 N 4 /3D‐C) is designed to stabilize the Na plating/stripping behavior. The sodiophilicity is endowed by a highly reversible adsorption‐intercalation process at the hetero‐interface, which can guide conformal Na deposition and induce the formation of inorganic‐rich solid‐electrolyte interphases with high structural stability and fast Na‐ion transport. Meanwhile, the 3D scaffold can effectively accommodate Na deposition during Na plating/stripping and depress the dendrite formation. As a result, the half cell assembled with g ‐C 3 N 4 /3D‐C electrode delivers long‐term cycling performance at 1.0 mA cm −2 with a high Coulombic efficiency of 99.92% for over 2000 cycles and of 99.94% even at 5 mA cm −2 , 10 mAh cm −2 . The practical feasibility of the g ‐C 3 N 4 /3D‐C is verified with full cells, which shows favorable rate capability and long‐cycle performance. The sodiophilic hetero‐interface construction strategy proposed in this work sparks new insights for designing high‐performance Na metal anodes.