Lithiation: A Pathway to Strengthen Sodiophilic Metal Interlayer of 3D Metallic Skeleton for High-Performance Sodium Metal Anodes

Constructing a three-dimensional (3D) skeleton with a sodiophilic-modified layer (SML) has been proven to be an effective strategy to alleviate excessive volumetric deformation and continuous dendrite growth for sodium (Na) metal anodes. However, the weak binding force and violent reaction between the SML and the 3D skeleton lead to numerous cracks/defects and even pulverization of the SML during repeated Na plating/stripping. Herein, a lithiation pathway is presented to construct a sodiophilic Li-Sn alloy layer onto a 3D copper mesh to strengthen the SML for stable Na metal anodes. The lithiation 3D skeleton exhibits superior sodiophilicity, higher charge-transfer efficiency, and lower ion-diffusion barrier, contributing to the homogenization of ion-electronic flux and Na deposition. Simultaneously, the dense Li-Sn alloy is more stable than the monometal Sn-layer, which effectively prevents damage to the SML and enhances the stability of the SML. As a result, the asymmetrical cell exhibits great performance with a negligible nucleation overpotential and a high average Coulombic efficiency of 99.4%. Moreover, the full cell assembled with Na₃V₂(PO₄)₃ cathode delivers superior capacity retention of 91.3% after 1000 cycles at a current of 3C.