Locking-chain electrolyte additive enabling moisture-tolerant electrolytes for sodium-ion batteries.

Li, Wenbin; Duan, Yijie; Ge, Shaohua; Wu, Wenbo; Song, Keming; Zhang, Jiyu; Tang, Guochuan; Zhao, Lingfei et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The unstable electrolyte-electrode interface and the trace H<sub>2</sub>O in commercial organic electrolytes critically limit the cycling life of batteries. Herein, a locking-chain sodium 4,4'-(1,4-phenylenebis(oxy))-bis(butane-1-sulfonate)-15-crown-5 (15PBS) is designed for phase-to-interface electrolyte optimization. In the electrolyte phase, the strong hydrophilic sulfonate groups and 15-crown-5 in 15PBS effectively transform H<sub>2</sub>O from a reactive aggregated state (strong H-bond) into an inactive state (weak H-bond) through adsorption, effectively suppressing H<sub>2</sub>O-induced electrolyte decomposition. At the electrolyte-electrode interface, 15PBS preferentially adsorbed onto hard carbon, displacing solvents within the electric double layer to form insoluble phenyl-rich sulfide solid electrolyte interphase with fast Na<sup>+</sup> transport. Simultaneously, 15PBS facilitates the formation of stable cathode-electrolyte interphase on Na<sub>0.72</sub>Ni<sub>0.32</sub>Mn<sub>0.68</sub>O<sub>2</sub>, improving Na<sup>+</sup> migration kinetics and cycling reversibility. The hard carbon | |Na<sub>0.72</sub>Ni<sub>0.32</sub>Mn<sub>0.68</sub>O<sub>2</sub> full cell with high specific energy of 191.7 Wh kg<sup>-1</sup> (based on the total active-material mass) delivers long lifespan of 2000 cycles at 500 mA g<sup>-1</sup>. Moreover, 15PBS is compatible with ester-based electrolytes in lithium-ion batteries, enabling stable cycling of commercial graphite and Si/C negative electrodes. This work provides an effective approach for durable electrolytes towards safe and high-performance batteries.