Synergistic Manipulation of Na+ Flux and Surface‐Preferred Effect Enabling High‐Areal‐Capacity and Dendrite‐Free Sodium Metal Battery

The propensity of sodium anode to form uniform electrodeposit is bound up with the nature of electrode surface and regulation of Na-ion flux, as well as distribution of electronic field, which is quite crucial for high-areal-capacity sodium metal batteries (SMBs). Herein, a novel metallic sodium/sodium-tin alloy foil anode (Na/NaSn) with 3D interpenetrated network and porous structure is prepared through facile alloy reaction. The strong sodiophilic properties of sodium-tin alloy can lower the nucleation energy, resulting in smaller depositing potential and strong adsorption of Na+ , while synergistic effect of porous skeleton and additional potential difference (≈0.1 V) between Na and Na-Sn alloy (Na15 Sn4 ) can alleviate volume expansion, redistribute the Na-ion flux and regulate electronic field, which favors and improves homogeneous Na deposition. The as-fabricated Na/NaSn electrode can endow excellent plating/stripping reversibility at high areal capacity (over 1600 h for 4 mAh cm-2 at 1 mA cm-2 and 2 mAh cm-2 at 2 mA cm-2 ), fast electrochemical kinetics (500 h under 4 mAh cm-2 at 4 mA cm-2 ) and superior rate performances. A novel strategy in the design of high-performance Na anodes for large-scale energy storage is provided.