In Situ Constructed Ionic-Electronic Dual-Conducting Scaffold with Reinforced Interface for High-Performance Sodium Metal Anodes

The formation of severe dendritic sodium (Na) microstructure reduces the reversibility of anode and further hinders its practical implementation. In this work, an ionic-electronic dual-conducting (IEDC) scaffold composed of Na₃P and carbon nanotubes is in situ developed by a scalable strategy with subsequent alloying reaction, for realizing dendrite-free Na deposition under high current density and large areal capacity. The in situ formed Na₃P with high sodiophilicity not only sets up a hierarchically efficient ionic conducting network, but also participates in the construction of reinforced solid electrolyte interphase, while carbon nanotubes can assemble an electronic conducting framework. As a result, the multifunctional IEDC scaffold contributes to smooth Na plating and exceptionally reversible Na stripping. High average Coulombic efficiency of 99.8% after prolonged 1200 cycles at 3 mA cm⁻² and small overpotential of 20 mV over 250 h (equals to 530 cycles) at high rate of 5 mA cm⁻² are obtained. The high availability of Na in IEDC scaffold enables the impressive performance of full cell with limited Na, using Na₃V₂(PO₄)₃ (NVP) cathode at practical level. More importantly, the as-developed anode-free full cell with IEDC||NVP configuration delivers a high capacity retention with long lifetime, indicating its great potential for practical Na metal batteries.