Nitrogen‐Rich Solvation Structures Enable Long‐Cycle Sodium Metal Batteries

Abstract Sodium (Na) metal anode exhibits excellent prospects in rechargeable battery systems owing to its high theoretical capacity (1166 mAh g −1 ) and its high abundance in the crust (2.3%). However, the electrochemical/mechanical unstable electrode interphases induce the rapid battery performance degradation and severely hinder the wide applications of Na metal batteries (SMBs). Herein, a nitrogen‐enriched coordinated solvation structure (NECS) is designed to simultaneously stabilize both electrodes through the innovation of solvation‐structure‐derived interphases engineering. The NECS‐derived N/O‐rich inorganic solid electrolyte interphase enables uniform and dendrite‐free Na plating/stripping for a working Na anode. NECS‐derived cathode electrolyte interphase, composed of NaN x O y , Na 3 N, and other Na containing compounds, significantly enhances the structural stability and electrochemical reversibility of the NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (NFM) cathode. The Na||Na symmetric cell with NECS electrolyte remains stable for more than 4000 h. Besides, the Na||NFM full cell achieves 1000 cycles with 86.1% capacity retention using a high loading electrode of 7.5 mg cm −2 . The Na||NFM pouch cell configuration demonstrates a high energy density of 202.6 Wh kg −1 , underscoring the practicality of the proposed electrolyte strategy. The strategy solvation structure modulation proposed in this work offers a universal approach to overcoming the challenge between high‐energy‐density and long‐lifespan of SMBs.