Building Fast Ion-Conducting Pathways on 3D Metallic Scaffolds for High-Performance Sodium Metal Anodes

Building3D electron-conducting scaffolds has been proven to bean effective way to alleviate severe dendritic growth and infinitevolume change of sodium (Na) metal anodes. However, the electroplatedNa metal cannot completely fill these scaffolds, especially at highcurrent densities. Herein, we revealed that the uniform Na platingon 3D scaffolds is strongly related with the surface Na+ conductivity. As a proof of concept, we synthesized NiF2 hollow nanobowls grown on nickel foam (NiF2@NF) to realizehomogeneous Na plating on the 3D scaffold. The NiF2 canbe electrochemically converted to a NaF-enriched SEI layer, whichsignificantly reduces the diffusion barrier for Na+ ions.The NaF-enriched SEI layer generated along the Ni backbones creates3D interconnected ion-conducting pathways and allows for the rapidNa(+) transfer throughout the entire 3D scaffold to enabledensely filled and dendrite-free Na metal anodes. As a result, symmetriccells composed of identical Na/NiF2@NF electrodes showdurable cycle life with an exceedingly stable voltage profile andsmall hysteresis, particularly at a high current density of 10 mAcm(-2) or a large areal capacity of 10 mAh cm(-2). Moreover, the full cell assembled with a Na3V2(PO4)(3) cathode exhibitsa superior capacity retention of 97.8% at a high current of 5C after300 cycles.

Automated summary

Building 3D electron-conducting scaffolds is an effective way to alleviate dendritic growth and volume change of sodium (Na) metal anodes. A uniform Na plating on the 3D scaffold is achieved by synthesizing NiF2 hollow nanobowls grown on nickel foam (NiF2@NF), which can be electrochemically converted to a NaF-enriched SEI layer. The NaF-enriched SEI layer enables rapid Na(+) transfer throughout the entire 3D scaffold, resulting in densely filled and dendrite-free Na metal anodes.