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-C₃N₄ coating layers (g-C₃N₄/3D-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-C₃N₄/3D-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-C₃N₄/3D-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.