Nitrogen-Rich Solvation Structures Enable Long-Cycle Sodium Metal Batteries.

Xue, Zhou-Qing; Zhao, Chen-Zi; Chen, Yao-Peng; Yang, Shi-Jie; Yang, Yi; Wang, Shuai-Qi; Wang, Zi-You; Zhu, Han-Bing et al. · Adv Mater · 2026

basic_science · Level V

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Abstract

Sodium (Na) metal anode exhibits excellent prospects in rechargeable battery systems owing to its high theoretical capacity (1166 mAh g<sup>-1</sup>) 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<sub>x</sub>O<sub>y</sub>, Na<sub>3</sub>N, and other Na containing compounds, significantly enhances the structural stability and electrochemical reversibility of the NaNi<sub>1/3</sub>Fe<sub>1/3</sub>Mn<sub>1/3</sub>O<sub>2</sub> (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<sup>-2</sup>. The Na||NFM pouch cell configuration demonstrates a high energy density of 202.6 Wh kg<sup>-1</sup>, 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.