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

Abstract

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 Na3 P 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 Na3 P 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 3mA cm-2 and small overpotential of 20mV over 250 h (equals to 530 cycles) at high rate of 5mA cm-2 are obtained. The high availability of Na in IEDC scaffold enables the impressive performance of full cell with limited Na, using Na3 V2 (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.